Petroleum Experts
User Manual
IPM PROSPER Version 11.5 May 2011
PROSPER IPM - Single Well Model OVERVIEW by Petroleum Experts Limited
PROSPER is a well performance, design and optimisation program which is part of the Integrated Production Modelling Toolkit (IPM). This tool is the industry standard well modelling with the major operators worldwide. PROSPER is designed to allow the building of reliable and consistent well models, with the ability to address each aspect of well bore modelling VIZ, PVT (fluid characterisation), VLP correlations (for calculation of flow-line and tubing pressure loss) and IPR (reservoir inflow). PROSPER provides unique matching features, which tune PVT, multiphase flow correlations and IPR to match measured field data, allowing a consistent well model to be built prior to use in prediction (sensitivities or artificial lift design). PROSPER enables detailed surface pipeline performance and design: Flow Regimes, pipeline stability, Slug Size andFrequency APPLICATIONS • Design and optimise well completions including multi-lateral, multilayer and horizontal wells • Design and optimise tubing and pipeline sizes • Design, diagnose and optimise Gas lifted, Hydraulic pumps and ESP wells • Generate lift curves for use in simulators • Calculate pressure losses in wells, flow lines and across chokes • Predict flowing temperatures in wells and pipelines • Monitor well performance to rapidly identify wells requiring remedial action • Calculate total skin and determine breakdown (damage, deviation or partial penetration) • Unique black oil model for retrograde condensate fluids, accounting for liquid dropout in the wellbore • Allocate production between wells
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Copyright Notice The copyright in this manual and the associated computer program are the property of Petroleum Experts Ltd. All rights reserved. Both, this manual and the computer program have been provided pursuant to a Licence Agreement containing restriction of use. No part of this manual may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language, in any form or by any means, electronic, mechanical, magnetic, optical or otherwise, or disclose to third parties without prior written consent from Petroleum Experts Ltd., Petex House, 10 Logie Mill, Edinburgh, EH7 4HG, Scotland, UK. © Petroleum Experts Ltd. All rights reserved. IPM Suite, GAP, PROSPER, MBAL, PVTP, REVEAL, RESOLVE, IFM, ModelCatalogue and OpenServer are trademarks of Petroleum Experts Ltd. Microsoft (Windows), Windows (2000) and Windows (XP) are registered trademarks of the Microsoft Corporation The software described in this manual is furnished under a licence agreement. The software may be used or copied only in accordance with the terms of the agreement. It is against the law to copy the software on any medium except as specifically allowed in the license agreement. No part of this documentation may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or information storage and retrieval systems for any purpose other than the purchaser's personal use, unless express written consent has been given by Petroleum Experts Limited.
Address: Petroleum Experts Limited Petex House 10 Logie Mill Edinburgh, Scotland EH7 4HG Tel : (44 131) 474 7030 Fax : (44 131) 474 7031 email:
[email protected] Internet: www.petex.com © 1990-2011 Petroleum Experts Limited
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PROSPER
Table of Contents 0
Chapter 1
Technical Overview
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1 Fluid modelling ................................................................................................................................... options 2 2 Inflows................................................................................................................................... and Sand Control options 4 3 Well bore ................................................................................................................................... and Pipeline hydraulics 6 4 Artificial ................................................................................................................................... lift systems 7 5 Flow assurance ................................................................................................................................... 8 Advanced Therm .......................................................................................................................................................... al Models 8 General Flow Assurance .......................................................................................................................................................... Features 8
6 What's ................................................................................................................................... New 9 7 Examples ................................................................................................................................... Guide 35
Chapter 2
User Guide
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1 Introduction ................................................................................................................................... 39 Using PROSPER .......................................................................................................................................................... 39 PROSPER and .......................................................................................................................................................... System s Analysis 42 About PROSPER ......................................................................................................................................................... 44 Exam ples .......................................................................................................................................................... 46
2 File Management ................................................................................................................................... 47 PROSPER Files.......................................................................................................................................................... 47 PVT Data (*.PVT) ......................................................................................................................................................... 47 Input Data (*.SIN) ......................................................................................................................................................... 48 Analysis Data ......................................................................................................................................................... (*.ANL) 48 Output Data ......................................................................................................................................................... (*.OUT) 48 Creating a ......................................................................................................................................................... New File 49 Opening an......................................................................................................................................................... Existing File 49 Saving a File ......................................................................................................................................................... 49 Copying a File ......................................................................................................................................................... 50 Preferences .......................................................................................................................................................... 50 Main Screen ......................................................................................................................................................... 50 File ......................................................................................................................................................... 52 Plot ......................................................................................................................................................... 53 User Applications ......................................................................................................................................................... 55 Limits ......................................................................................................................................................... 56 Units ......................................................................................................................................................... 58 Equipment ......................................................................................................................................................... 59 VPC ......................................................................................................................................................... 59 Softw are Key .......................................................................................................................................................... Maintenance 60 FileList .......................................................................................................................................................... 63 Evaluate OpenServer .......................................................................................................................................................... Statem ent 64 User Correlations .......................................................................................................................................................... 66 Printer Setup .......................................................................................................................................................... 67 Preparing to ......................................................................................................................................................... Print 67 Selecting and ......................................................................................................................................................... configuring a Printer 68 Printing Export ......................................................................................................................................................... Data 68
Contents
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Selecting an ......................................................................................................................................................... Exported Data to Print 70 Word Processing .......................................................................................................................................................... in PROSPER 70 Clipboard Com .......................................................................................................................................................... m and 71 Com m and Buttons .......................................................................................................................................................... 71
3 Data Input ................................................................................................................................... - General 73 PROSPER Main.......................................................................................................................................................... Menu 73 File ......................................................................................................................................................... 74 Options ......................................................................................................................................................... 74 PVT ......................................................................................................................................................... 74 System ......................................................................................................................................................... 75 Matching ......................................................................................................................................................... 75 Calculation......................................................................................................................................................... 75 Design ......................................................................................................................................................... 75 Output ......................................................................................................................................................... 75 Wizard ......................................................................................................................................................... 76 Units ......................................................................................................................................................... 76 Help ......................................................................................................................................................... 76 Options - Options .......................................................................................................................................................... Selection 76 Fluid Description ......................................................................................................................................................... 77 Fluid Type ......................................................................................................................................... 78 Method ......................................................................................................................................... 78 Equation of State......................................................................................................................................... Setup 78 Separator ......................................................................................................................................... 79 Emulsions ......................................................................................................................................... 79 Hydrates ......................................................................................................................................... 79 Water Viscosity ......................................................................................................................................... 79 Water Vapour ......................................................................................................................................... 80 Viscosity model ......................................................................................................................................... 80 Well ......................................................................................................................................................... 80 Flow Type ......................................................................................................................................... 80 Well Type ......................................................................................................................................... 80 Artificial Lift ......................................................................................................................................................... 81 Method ......................................................................................................................................... 81 Type ......................................................................................................................................... 82 Calculation......................................................................................................................................................... Type 84 Predict ......................................................................................................................................... 84 Model ......................................................................................................................................... 84 Calculation ......................................................................................................................................... 86 Output ......................................................................................................................................... 86 Steam Calculation ......................................................................................................................................................... 86 Well Completion ......................................................................................................................................................... 86 Type ......................................................................................................................................... 86 Sand Control ......................................................................................................................................... 86 Reservoir ......................................................................................................................................................... 87 Type ......................................................................................................................................... 87 Gas Coning ......................................................................................................................................... 87 User Information ......................................................................................................................................................... and Comments 87 Options - Perforating .......................................................................................................................................................... Gun DataBase 87 Options - Tubing .......................................................................................................................................................... DataBase 90 Options - Casing .......................................................................................................................................................... DataBase 91 Options - Pipe.......................................................................................................................................................... Schedule 91
4 PVT Data ................................................................................................................................... Input 92 Introduction .......................................................................................................................................................... 92
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PROSPER Black Oil - Oil and .......................................................................................................................................................... Water 94 Input Data ......................................................................................................................................................... 94 Black Oil Compressibility ......................................................................................................................................... Calculation 96 Tables ......................................................................................................................................................... 96 Match Data......................................................................................................................................................... 97 Regression......................................................................................................................................................... 98 Match ......................................................................................................................................... 99 Match All ................................................................................................................................... 100 Parameters ................................................................................................................................... 100 View ing the Match ................................................................................................................................... Parameters 100 Matching FVF above ................................................................................................................................... Bubble Point 101 Correlations ......................................................................................................................................................... 101 Calculate ......................................................................................................................................................... 102 Calculating PVT......................................................................................................................................... Data 102 Displaying the Calculated ......................................................................................................................................... Data on the screen 103 Plotting the Calculated ......................................................................................................................................... Data 104 Saving PVT tables ......................................................................................................................................... from Calculated Data 105 Save the ......................................................................................................................................................... PVT Data 105 Open ......................................................................................................................................................... 105 Composition ......................................................................................................................................................... 106 Emulsions......................................................................................................................................................... 107 Emulsions ......................................................................................................................................... 107 Non-New ......................................................................................................................................................... tonian Fluid 110 Pow er Fluid ......................................................................................................................................................... Data 112 Hydrates ......................................................................................................................................................... Formation table 114 Black Oil - Dry .......................................................................................................................................................... And Wet Gas 115 Input Data......................................................................................................................................................... 115 Black Oil - Retrograde .......................................................................................................................................................... Condensate 117 Input Data......................................................................................................................................................... 117 Calculations ......................................................................................................................................................... 118 Export .......................................................................................................................................................... 119 Equation Of State .......................................................................................................................................................... - All Fluids 119 EOS Model ......................................................................................................................................................... Setup 121 EOS PVT......................................................................................................................................................... Input Data 126 Importing Matched ......................................................................................................................................... EoS 128 Using the......................................................................................................................................................... EoS 128 Generate PVT properties ......................................................................................................................................... 128 Phase Envelope......................................................................................................................................... 131 Target GOR ......................................................................................................................................... 133
5 Equipment ................................................................................................................................... Data Input 134 Predicting Pressure .......................................................................................................................................................... Only 134 Deviation ......................................................................................................................................................... Survey 135 Filter ......................................................................................................................................... 138 Surface Equipment ......................................................................................................................................................... 142 Dow nhole......................................................................................................................................................... Equipment 146 Temperature ......................................................................................................................................................... Survey 148 Pipe Schedule ......................................................................................................................................................... and Equipment 149 Predicting Pressure .......................................................................................................................................................... and Tem perature 153 Rough Approximation ......................................................................................................................................................... 153 Deviation Survey......................................................................................................................................... 154 Surface Equipment ......................................................................................................................................... 154 Dow nhole Equipment ......................................................................................................................................... 154 Geothermal Gradient ......................................................................................................................................... 155 Average Heat Capacities ......................................................................................................................................... 155
Contents
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Enthalpy Balance ......................................................................................................................................................... 156 Deviation Survey......................................................................................................................................... 157 Surface Equipment ......................................................................................................................................... 157 Dow nhole Equipment ......................................................................................................................................... 160 Temperature Data ......................................................................................................................................... 161 Drilling and Completion ......................................................................................................................................... 162 Lithology ......................................................................................................................................... 164 Databases ......................................................................................................................................... 165 Improved ......................................................................................................................................................... Approximation 167 Deviation Survey......................................................................................................................................... 168 Surface Equipment ......................................................................................................................................... 168 Dow nhole Equipment ......................................................................................................................................... 169 Temperature Data ......................................................................................................................................... 169
6 IPR Data ................................................................................................................................... Input 171 IPR Single Well .......................................................................................................................................................... Data 172 The Main ......................................................................................................................................................... Data Entry Screen 172 Section Buttons ......................................................................................................................................................... 173 Action Buttons ......................................................................................................................................................... 173 Model Selection ......................................................................................................................................................... Screen 175 Data Input......................................................................................................................................................... Screen 176 IPR Models for .......................................................................................................................................................... Oil and Water Wells 178 P.I. Entry ......................................................................................................................................................... 179 Vogel ......................................................................................................................................................... 179 Composite......................................................................................................................................................... 179 Darcy ......................................................................................................................................................... 180 Fetkovich......................................................................................................................................................... 180 Multi-rate ......................................................................................................................................................... Fetkovich 180 Jones ......................................................................................................................................................... 180 Multi-rate ......................................................................................................................................................... Jones 181 Transient......................................................................................................................................................... 181 Hydraulically ......................................................................................................................................................... Fractured Well 182 Horizontal......................................................................................................................................................... Well - No Flow Boundaries 183 Horizontal......................................................................................................................................................... Well - Constant Pressure Upper Boundary 184 Multi-Layer ......................................................................................................................................................... Inflow 185 External Entry ......................................................................................................................................................... 186 Horizontal......................................................................................................................................................... w ell - dP Friction Loss in Wellbore 188 Multi-Layer ......................................................................................................................................................... - dP Loss in Wellbore 192 SkinAide ......................................................................................................................................................... 195 Dual Porosity ......................................................................................................................................................... 195 Horizontal......................................................................................................................................................... Well w ith Transverse Vertical Fractures 195 Thermally......................................................................................................................................................... Induced Fracture Model 196 Overview ......................................................................................................................................... 196 Data Entry ......................................................................................................................................... 197 Relative Permeability ......................................................................................................................................................... Curves 198 Test Data ......................................................................................................................................... 200 Plot ......................................................................................................................................... 200 Relative Permeability ......................................................................................................................................... Calculation Details 201 Coning Calculation ......................................................................................................................................................... 202 IPR for Gas and .......................................................................................................................................................... Retrograde Condensate 203 Jones ......................................................................................................................................................... 203 Forchheimer ......................................................................................................................................................... 204 Back Pressure ......................................................................................................................................................... 204 C and n ......................................................................................................................................................... 204 Multi-rate ......................................................................................................................................................... C and n 205
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PROSPER Multi-rate ......................................................................................................................................................... Jones 206 External Entry ......................................................................................................................................................... 206 Petroleum......................................................................................................................................................... Experts 206 Hydraulically ......................................................................................................................................................... Fractured Well 209 Horizontal......................................................................................................................................................... Well - No-Flow Boundaries 209 Multi-layer......................................................................................................................................................... Inflow 209 Horizontal......................................................................................................................................................... Well - dP Friction Loss in Wellbore 209 Dual Porosity ......................................................................................................................................................... 209 Horizontal......................................................................................................................................................... Well w ith Transverse Vertical Fractures 210 Multi-Layer ......................................................................................................................................................... - dP Loss in Wellbore 210 Modified Isochronal ......................................................................................................................................................... Inflow Model 210 Forchheimer ......................................................................................................................................................... w ith Pseudo Pressure 211 Multirate Forchheimer ......................................................................................................................................................... w ith Pseudo Pressure 212 Skin Models .......................................................................................................................................................... 212 Mechanical/Geometrical ......................................................................................................................................................... Skin 212 Deviation/Partial ......................................................................................................................................................... Penetration Skin 217 Sand Control.......................................................................................................................................................... Options 218 Gravel Packed ......................................................................................................................................................... Completion 220 Pre-Packed ......................................................................................................................................................... Screen completion 223 Wire-Wrapped ......................................................................................................................................................... Screen Completion 227 Slotted Liner ......................................................................................................................................................... Completion 231 Other IPR-related .......................................................................................................................................................... features 235 Gravel Pack ......................................................................................................................................................... Completion Velocities 235 Viscosity Modelling .......................................................................................................................................................... 236 Com paction .......................................................................................................................................................... Perm eability Reduction 238 Injection Wells .......................................................................................................................................................... 239 SkinAide .......................................................................................................................................................... 240 SkinAide Theoretical ......................................................................................................................................................... Background 240 Position of the producing ......................................................................................................................................... interval w ith respect to reservoir geometry 240 Interference betw ......................................................................................................................................... een perforations and the damaged zone 241 The Crushed Zone ......................................................................................................................................... 242 Perforation tunnel ......................................................................................................................................... w hich penetrates the formation 242 Perforation tunnel ......................................................................................................................................... through the casing and cement 243 Annulus betw een ......................................................................................................................................... Casing and Screen 243 Hemispherical Flow ......................................................................................................................................... Model 244 Using SkinAide ......................................................................................................................................................... 245 Flow Model ......................................................................................................................................... 245 Skin Model ......................................................................................................................................... 246 Perforation Data......................................................................................................................................... 246 Geometry ......................................................................................................................................... 247 Petrophysics ......................................................................................................................................... 248 Damaged Zone ......................................................................................................................................... 249 Cased Hole ......................................................................................................................................... 250 Crushed Zone ......................................................................................................................................... 250 Perforations ......................................................................................................................................... 252 SPOT: Shell Perforating .......................................................................................................................................................... Optim isation Tool 259 Introduction ......................................................................................................................................................... to SPOT 259 Gun System ......................................................................................................................................................... databases 261 Gun ......................................................................................................................................... 266 Spot Perforation......................................................................................................................................... Calculations 268 SPOT: Model ......................................................................................................................................................... inputs 270 SPOT: Model inputs ......................................................................................................................................... - Options 272 SPOT: Model inputs ......................................................................................................................................... - Layers 280 SPOT: Model inputs ................................................................................................................................... - Rel Perm Data 285
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SPOT: Model inputs ................................................................................................................................... - Mud Invasion 289 SPOT: Model inputs ................................................................................................................................... - Old Gun 298 SPOT: Model inputs ......................................................................................................................................... - Log Data 300 SPOT: Model inputs ................................................................................................................................... - Generate Log Data 304 SPOT: Model inputs ................................................................................................................................... - Perforation Cutoff 304 SPOT: Model inputs ................................................................................................................................... - Perforation Depth 305 SPOT: Model inputs ......................................................................................................................................... - Completion 306 SPOT: Model inputs ......................................................................................................................................... - Gravel Pack 308 SPOT: Model ......................................................................................................................................................... Results 309 SPOT: Model Results ......................................................................................................................................... - Layer Results 310 SPOT: Model Results ......................................................................................................................................... - Log Results 311 Multi-Lateral.......................................................................................................................................................... Interface 312 Netw ork Interface ......................................................................................................................................................... 312 Motivation ......................................................................................................................................... 312 Interface Overview ......................................................................................................................................... 312 Netw ork Window ................................................................................................................................... 314 The Navigator Window ................................................................................................................................... 316 Toolbar Details ................................................................................................................................... 317 Netw ork Manipulation ................................................................................................................................... 318 Menu Details ................................................................................................................................... 319 Visualisation Screens ................................................................................................................................... 322 Data Entry......................................................................................................................................................... 324 Overview ......................................................................................................................................... 324 Tie-point and Junction ......................................................................................................................................... Data 324 Tubing Data ......................................................................................................................................... 324 Completion Data......................................................................................................................................... 325 Reservoir Data ......................................................................................................................................... 325 Example of ......................................................................................................................................................... How to Set Up a Simple System 326 Introduction ......................................................................................................................................... 326 Place the Nodes......................................................................................................................................... in the Netw ork Window 327 Connect the Nodes ......................................................................................................................................... 327 Enter the Data ......................................................................................................................................... 327 Visualise / Calculate ......................................................................................................................................... 329
7 Artificial ................................................................................................................................... Lift Data Input 329 Continuous Gas .......................................................................................................................................................... Lift Input Data 329 Fixed Depth ......................................................................................................................................................... Of Injection 330 Optimum Depth ......................................................................................................................................................... of Injection 331 Valve Depth ......................................................................................................................................................... Specified 332 Gas Lift (Safety ......................................................................................................................................................... Equipment) 333 Gas Lift (Allow ......................................................................................................................................................... injection in Pipe Line above w ellhead) 335 Interm ittent .......................................................................................................................................................... Gas Lift 337 ESP Input Data .......................................................................................................................................................... 337 HSP Input Data .......................................................................................................................................................... 339 Progressive .......................................................................................................................................................... Cavity Pum ps 340 Coiled Tubing .......................................................................................................................................................... Gas Lift 343 Diluent Injection .......................................................................................................................................................... 344 Jet Pum ps .......................................................................................................................................................... 345 Multiphase Pum .......................................................................................................................................................... ps 346 Sucker Rod Pum .......................................................................................................................................................... ps 347
8 Matching ................................................................................................................................... Menu 348 VLP/IPR Match .......................................................................................................................................................... and Quality Check 350 VLP Matching ......................................................................................................................................................... 354 VLP Correlation ......................................................................................................................................... Applications 356
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PROSPER IPR Matching ......................................................................................................................................................... 357 Gradient Matching .......................................................................................................................................................... 360 Surface Pipe.......................................................................................................................................................... Matching 362 Correlation Com .......................................................................................................................................................... parison 363 QuickLook for .......................................................................................................................................................... Gas Lift 369 Input ......................................................................................................................................................... 369 Performing ......................................................................................................................................................... the QuickLook Calculation 373 QuickLook for .......................................................................................................................................................... ESP 376 Input ......................................................................................................................................................... 376 Performing ......................................................................................................................................................... the QuickLook Calculation 378 QuickLook for .......................................................................................................................................................... HSP 380 Input ......................................................................................................................................................... 381 Performing ......................................................................................................................................................... the QuickLook Calculation 383 Tubing Param .......................................................................................................................................................... eters 385 Pipeline Param .......................................................................................................................................................... eters 385 Correlation Thresholds .......................................................................................................................................................... 385
9 Calculation ................................................................................................................................... Menu 385 Inflow (IPR) .......................................................................................................................................................... 386 System (Ipr +.......................................................................................................................................................... Vlp) 391 Left - Hand ......................................................................................................................................................... Intersection for VLP/IPR curves 393 Sensitivity......................................................................................................................................................... Variables Screen 394 Sensitivity Combinations ......................................................................................................................................... Screen 396 Calculation ......................................................................................................................................................... Screen 397 Gradient (Traverse) .......................................................................................................................................................... 407 Options ......................................................................................................................................................... 410 Maximum Grain Diameter ......................................................................................................................................... 410 Erosional Velocity ......................................................................................................................................... Calculation for Sand Laden Fluids 413 Gradient (Traverse)-Modified ......................................................................................................................................... Turner Equation 415 Pigging ......................................................................................................................................... 417 Note on HSP ......................................................................................................................................................... 417 VLP (Tubing .......................................................................................................................................................... Curves) 418 VLP (Tubing) ......................................................................................................................................................... Curves - 3 Variables 418 VLP (Tubing) ......................................................................................................................................................... Curves - 4 Variables 423 VLP (Tubing) ......................................................................................................................................................... - Multi Variables 427 Choke Perform .......................................................................................................................................................... ance 427 Generate for.......................................................................................................................................................... GAP 430 Bottom Hole .......................................................................................................................................................... Pressure from Wellhead Pressure 430 References ......................................................................................................................................................... 433 Note on Enthalpy .......................................................................................................................................................... Balance Model 433 Reset Results .......................................................................................................................................................... 434
10 Design ................................................................................................................................... Menu 435 Continuous Gas .......................................................................................................................................................... Lift Design 436 Menu Options ......................................................................................................................................................... 436 New Well......................................................................................................................................................... 437 Setting Up the Design ......................................................................................................................................... Problem 438 Gas Lift Valve Selection ......................................................................................................................................... 443 Performing the Design ......................................................................................................................................... (New Well) 444 Existing Mandrels ......................................................................................................................................................... Design 449 Setting Up the Design ......................................................................................................................................... Problem 450 Defining the Depths ......................................................................................................................................... of Existing Mandrels 450 Gas Lift Valve Selection ......................................................................................................................................... 452 Performing the Design ......................................................................................................................................... (Existing Mandrels) 452 Valve Spacing ......................................................................................................................................... 456
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Designing w ith Tubing ......................................................................................................................................... Sensitive Valves 456 Spacing Procedure ......................................................................................................................................... for Tubing Sensitive Valves 457 Proportional Valves ......................................................................................................................................... 458 Gas Lift Adjustments ......................................................................................................................................................... 461 Gaslift Valve ......................................................................................................................................................... Performance 465 Valve Performance ......................................................................................................................................... Clearinghouse (VPC) 465 Interm ittent .......................................................................................................................................................... Gas Lift 466 Electrical Subm .......................................................................................................................................................... ersible Pum p Design 470 ESP Calculate ......................................................................................................................................................... 472 Checking Suitability ......................................................................................................................................... of Separator Efficiency 474 ESP Design ......................................................................................................................................................... (Pump, Motor and Cable Selection) 475 Checking the Pump ......................................................................................................................................... Design 477 Hydraulic Pum .......................................................................................................................................................... p Design 478 HSP Calculate ......................................................................................................................................................... 480 HSP Design ......................................................................................................................................................... (Pump and Turbine Selection) 481 Checking the Pump/Turbine ......................................................................................................................................... Design 483 Progressive .......................................................................................................................................................... Cavity Pum p Design 484 PCP Calculate ......................................................................................................................................................... 485 PCP Design ......................................................................................................................................................... (Pump and Rod Selection) 487 Coiled Tubing .......................................................................................................................................................... GasLift Design 488 Jet Pum p Design .......................................................................................................................................................... 490 Jet Pump ......................................................................................................................................................... Calculate 491 Jet Pump ......................................................................................................................................................... Design (Pump Selection) 493 Sucker Rod Pum .......................................................................................................................................................... p Design 494 Background ......................................................................................................................................................... 494 Design Sucker ......................................................................................................................................................... Rod Pump 497 Enter Design Parameters ......................................................................................................................................... 498 Perform Design ......................................................................................................................................... 499 Rod Sensitivity ......................................................................................................................................... 500 Artificial Lift .......................................................................................................................................................... Database 502 Gas Lift Valve ......................................................................................................................................................... Database 503 Adding a New Valve ......................................................................................................................................... 504 ESP Database ......................................................................................................................................................... 505 Pump Database ......................................................................................................................................... 505 Adding a New Pump ................................................................................................................................... 507 Motor Database......................................................................................................................................... 509 Adding a New Motor ................................................................................................................................... 510 Cables Database ......................................................................................................................................... 511 Adding a New Cable ................................................................................................................................... 511 HSP Database ......................................................................................................................................................... 512 Pumps Database......................................................................................................................................... 512 Adding a New Pump ......................................................................................................................................... 513 Turbines Database ......................................................................................................................................... 513 Adding a New Turbine ......................................................................................................................................... 514 PCP Database ......................................................................................................................................................... 515 Pumps Database......................................................................................................................................... 515 Adding a New Pump ................................................................................................................................... 517 Sucker Rods Database ......................................................................................................................................... 518 Adding a New Sucker ................................................................................................................................... Rod 519 Jet Pumps......................................................................................................................................................... Database 520 Pumps Database......................................................................................................................................... 520 Adding a New Pump ................................................................................................................................... 521 MultiPhase ......................................................................................................................................................... Pumps Database 521 Pumps Database......................................................................................................................................... 522
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PROSPER Adding a New Pump ......................................................................................................................................... 523 Sucker Rod ......................................................................................................................................................... Pump 524 Pump database ......................................................................................................................................... 524 Adding a New Pump ................................................................................................................................... 525 Sucker Rods Database ......................................................................................................................................... 526 Adding a New Sucker ................................................................................................................................... Rod 527
11 Output ................................................................................................................................... 528 Report .......................................................................................................................................................... 529 Setting Up......................................................................................................................................................... the Reporting System 529 Reports ......................................................................................................................................................... 529 Export .......................................................................................................................................................... 544 Export Setup ......................................................................................................................................................... 544 Plot .......................................................................................................................................................... 546 Plot Command ......................................................................................................................................................... Summary 547 Wellhead ......................................................................................................................................................... Plot 550 System Multi-Variable ......................................................................................................................................................... Plotting 550
12 Units................................................................................................................................... 552 Units Sum m ary .......................................................................................................................................................... 552 Unit Systems ......................................................................................................................................................... 553 Changing......................................................................................................................................................... Unit Systems for some variables 554 Changing......................................................................................................................................................... the Units 555 Validation......................................................................................................................................................... Limits 556 Units Details .......................................................................................................................................................... 556 Units Reset .......................................................................................................................................................... 557 Units Save .......................................................................................................................................................... 557
13 Wizard ................................................................................................................................... 557 Running the .......................................................................................................................................................... Wizard 557 Creating/Editing .......................................................................................................................................................... a Wizard 558 Notes of OS ......................................................................................................................................................... strings 559 Wizard examples ......................................................................................................................................................... 560
14 Help ................................................................................................................................... 560 Finding Inform .......................................................................................................................................................... ation in Help 561 Use the Search ......................................................................................................................................................... feature in Help 561 Use the Help ......................................................................................................................................................... Index 561 Context Sensitive ......................................................................................................................................................... Help 561 Accessing Help .......................................................................................................................................................... 561 Help Through ......................................................................................................................................................... the Menu 561 Getting Help ......................................................................................................................................................... Using the Mouse 561 Getting Help ......................................................................................................................................................... Using the Keyboard 562 To Minimise ......................................................................................................................................................... Help 562 Flow Correlations .......................................................................................................................................................... 562 Open Server.......................................................................................................................................................... 562 Help About PROSPER .......................................................................................................................................................... 562 Web Options.......................................................................................................................................................... 563
15 Appendix ................................................................................................................................... 564 A - References .......................................................................................................................................................... 564 PVT Calculations ......................................................................................................................................................... 564 CO2 Injection ......................................................................................................................................... 565 PVT Separator Pressure ......................................................................................................................................... 565 IPR Calculations ......................................................................................................................................................... 567 Multiphase ......................................................................................................................................................... Flow Calculations 569 Temperature ......................................................................................................................................................... Calculations 570
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Artificial Lift ......................................................................................................................................................... Design 570 B - Equations.......................................................................................................................................................... 571 Black Oil Model ......................................................................................................................................................... for Condensate 571 Mass Balance Calculations ......................................................................................................................................... 571 Using the mass ......................................................................................................................................... balance results to define Condensate Model 574 Estimation of CGRmin ......................................................................................................................................... 576 Multiphase ......................................................................................................................................................... Pseudo Pressure 577 Temperature ......................................................................................................................................................... Models 579 Rough Approximation ......................................................................................................................................... Temperature Model 580 Overall Heat Transfer ................................................................................................................................... Coefficient 581 Enthalpy Balance ......................................................................................................................................... 582 Default Thermal................................................................................................................................... Properties Database 588 Choke Calculation ......................................................................................................................................................... 589 Multi-Phase ......................................................................................................................................................... Flow Correlations 590 C - Dietz Shape .......................................................................................................................................................... Factors 617 D - File Form ats .......................................................................................................................................................... 619 Introduction ......................................................................................................................................................... 619 External PVT ......................................................................................................................................................... Tables 619 Lift Curves ......................................................................................................................................................... 621 IPR ......................................................................................................................................................... 622 ESP PUMPS ......................................................................................................................................................... 623 ESP MOTORS ......................................................................................................................................................... 624 ESP CABLES ......................................................................................................................................................... 625 HSP PUMPS ......................................................................................................................................................... 626 HSP TURBINES ......................................................................................................................................................... 627 E - Glossary .......................................................................................................................................................... 628 F - Im porting.......................................................................................................................................................... Data from Text Files 635
Chapter 3
Examples Guide
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1 Prosper ................................................................................................................................... Tutorials 641 Tutorial 00: Integrated .......................................................................................................................................................... Oil Well Model 643 Objectives......................................................................................................................................................... 643 Statement......................................................................................................................................................... of the Problem 644 General Approach ......................................................................................................................................................... 644 Available ......................................................................................................................................................... Data & Information 644 PVT Data from the ......................................................................................................................................... lab 646 Well Equipment Data ......................................................................................................................................... (Tubing etc) 647 Inflow Performance ......................................................................................................................................... Data 649 Multi-Rate Well Test ......................................................................................................................................... Data 650 Model Construction: ......................................................................................................................................................... Step by Step Procedure 650 Well Test ......................................................................................................................................................... Analysis: Step by Step 665 Sensitivity......................................................................................................................................................... Runs 684 Tutorial 01: Modelling .......................................................................................................................................................... a dry and w et gas producer 689 Statement......................................................................................................................................................... Of The Problem 690 PVT Input......................................................................................................................................................... Data 690 System Equipment ......................................................................................................................................................... Input Data 690 Deviation survey......................................................................................................................................... 690 Surface Equipment ......................................................................................................................................... 691 Dow n hole Equipment ......................................................................................................................................... 691 Static Geothermal ......................................................................................................................................... Gradient 691 Average Heat Capacities ......................................................................................................................................... 691 Reservoir......................................................................................................................................................... Input Data 692 Step by Step ......................................................................................................................................................... 692
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PROSPER System Options ......................................................................................................................................... 693 PVT data Input ......................................................................................................................................... 693 Saving the file ......................................................................................................................................... 694 System Equipment ......................................................................................................................................... Description 695 Deviation Survey ................................................................................................................................... 695 Surface Equipment ................................................................................................................................... 697 Dow n Hole Equipment ................................................................................................................................... 697 Geothermal gradient ................................................................................................................................... 698 Average Heat Capacities ................................................................................................................................... 699 Equipment Summary ................................................................................................................................... 700 Saving the PROSPER ................................................................................................................................... file 703 Inflow Performance ......................................................................................................................................... Relation (IPR) 703 Estimation of the......................................................................................................................................... w ell flow rate 707 Well Performance ......................................................................................................................................... Curve Generation 711 Lift Curve generation ......................................................................................................................................... for other applications 717 Introduction ................................................................................................................................... 717 Steps ................................................................................................................................... 718 Data Entry For Lift ................................................................................................................................... Curve Generation 718 Lift Curve generation ................................................................................................................................... 721 Lift Curve Inspection ................................................................................................................................... 722 Lift Curve Export ................................................................................................................................... 723 Tutorial 02: Modelling .......................................................................................................................................................... a naturally flow ing oil w ell 726 Statement......................................................................................................................................................... Of The Problem 726 PVT Input......................................................................................................................................................... Data 727 System Equipment ......................................................................................................................................................... Input Data 727 Deviation survey......................................................................................................................................... 727 Surface Equipment ......................................................................................................................................... 727 Dow n hole Equipment ......................................................................................................................................... 727 Static Geothermal ......................................................................................................................................... Gradient 728 Average Heat Capacities ......................................................................................................................................... 728 Reservoir......................................................................................................................................................... Input Data 728 Step by Step ......................................................................................................................................................... 729 System Options ......................................................................................................................................... 729 PVT data Input ......................................................................................................................................... 730 Saving the file ......................................................................................................................................... 731 System Equipment ......................................................................................................................................... Description 732 Deviation Survey ................................................................................................................................... 733 Surface Equipment ................................................................................................................................... 734 Dow n Hole Equipment ................................................................................................................................... 735 Geothermal gradient ................................................................................................................................... 736 Average Heat Capacities ................................................................................................................................... 737 Equipment Summary ................................................................................................................................... 738 Saving the PROSPER ................................................................................................................................... file 740 Inflow Performance ......................................................................................................................................... Relation (IPR) 741 Estimation of the......................................................................................................................................... w ell flow rate 744 Well Performance ......................................................................................................................................... Curve Generation 748 Lift Curve generation ......................................................................................................................................... for other applications 753 Introduction ................................................................................................................................... 753 Steps ................................................................................................................................... 754 Data Entry For Lift ................................................................................................................................... Curve Generation 754 Lift Curve generation ................................................................................................................................... 756 Lift Curve Inspection ................................................................................................................................... 757 Lift Curve Export ................................................................................................................................... 758 Tutorial 03: Modelling .......................................................................................................................................................... an oil w ell w ith black oil PVT m atching 761
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Statement......................................................................................................................................................... Of The Problem 761 PVT Input......................................................................................................................................................... Data 762 System Equipment ......................................................................................................................................................... Input Data 762 Deviation survey......................................................................................................................................... 762 Surface Equipment ......................................................................................................................................... 763 Dow n hole Equipment ......................................................................................................................................... 763 Static Geothermal ......................................................................................................................................... Gradient 763 Average Heat Capacities ......................................................................................................................................... 764 Reservoir......................................................................................................................................................... Input Data 764 Step by Step ......................................................................................................................................................... 764 System Options ......................................................................................................................................... 765 PVT data Input ......................................................................................................................................... 765 Saving the file ......................................................................................................................................... 769 System Equipment ......................................................................................................................................... Description 770 Deviation Survey ................................................................................................................................... 771 Surface Equipment ................................................................................................................................... 772 Dow n Hole Equipment ................................................................................................................................... 773 Geothermal gradient ................................................................................................................................... 774 Average Heat Capacities ................................................................................................................................... 775 Equipment Summary ................................................................................................................................... 776 Saving the PROSPER ................................................................................................................................... file 778 Inflow Performance ......................................................................................................................................... Relation (IPR) 778 Estimation of the......................................................................................................................................... w ell flow rate 782 Well Performance ......................................................................................................................................... Curve Generation 786 Lift Curve generation ......................................................................................................................................... for other applications 790 Introduction ................................................................................................................................... 790 Steps ................................................................................................................................... 791 Data Entry For Lift ................................................................................................................................... Curve Generation 791 Lift Curve generation ................................................................................................................................... 794 Lift Curve Inspection ................................................................................................................................... 795 Lift Curve Export ................................................................................................................................... 796 Tutorial 04: Modelling .......................................................................................................................................................... an horizontal oil w ell 798 Statement......................................................................................................................................................... Of The Problem 799 PVT Input......................................................................................................................................................... Data 799 System Equipment ......................................................................................................................................................... Input Data 799 Deviation survey......................................................................................................................................... 800 Surface Equipment ......................................................................................................................................... 800 Dow n hole Equipment ......................................................................................................................................... 800 Static Geothermal ......................................................................................................................................... Gradient 800 Average Heat Capacities ......................................................................................................................................... 801 Reservoir......................................................................................................................................................... Input Data 801 Step by Step ......................................................................................................................................................... 802 System Options ......................................................................................................................................... 802 PVT data Input ......................................................................................................................................... 803 Saving the file ......................................................................................................................................... 807 System Equipment ......................................................................................................................................... Description 807 Deviation Survey ................................................................................................................................... 808 Surface Equipment ................................................................................................................................... 809 Dow n Hole Equipment ................................................................................................................................... 810 Geothermal gradient ................................................................................................................................... 811 Average Heat Capacities ................................................................................................................................... 813 Equipment Summary ................................................................................................................................... 813 Saving the PROSPER ................................................................................................................................... file 815 Inflow Performance ......................................................................................................................................... Relation (IPR) 815
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PROSPER Sensitivity on w ......................................................................................................................................... ell length and w ater cut 819 Tutorial 05: Modelling .......................................................................................................................................................... a m ultilateral Dry Gas Producer 823 Statement......................................................................................................................................................... Of The Problem 824 PVT Input......................................................................................................................................................... Data 824 System Equipment ......................................................................................................................................................... Input Data 825 Deviation survey......................................................................................................................................... 825 Surface Equipment ......................................................................................................................................... 826 Dow n hole Equipment ......................................................................................................................................... 826 Static Geothermal ......................................................................................................................................... Gradient 826 Average Heat Capacities ......................................................................................................................................... 826 Multilateral......................................................................................................................................................... IPR Data 827 Step by Step ......................................................................................................................................................... 829 System Options ......................................................................................................................................... 830 PVT data Input ......................................................................................................................................... 830 Saving the file ......................................................................................................................................... 833 System Equipment ......................................................................................................................................... Description 834 Deviation Survey ................................................................................................................................... 835 Surface Equipment ................................................................................................................................... 837 Dow n Hole Equipment ................................................................................................................................... 837 Geothermal gradient ................................................................................................................................... 838 Average Heat Capacities ................................................................................................................................... 839 Equipment Summary ................................................................................................................................... 839 Saving the PROSPER ................................................................................................................................... file 841 Multilateral IPR Input ......................................................................................................................................... section 841 Estimation of the......................................................................................................................................... w ell flow rate and inspecting the detailled results 859 Tutorial 07: Modelling .......................................................................................................................................................... a slanted oil w ell 865 Statement......................................................................................................................................................... Of The Problem 865 PVT Input......................................................................................................................................................... Data 866 System Equipment ......................................................................................................................................................... Input Data 866 Deviation survey......................................................................................................................................... 866 Surface Equipment ......................................................................................................................................... 866 Dow n hole Equipment ......................................................................................................................................... 866 Static Geothermal ......................................................................................................................................... Gradient 867 Average Heat Capacities ......................................................................................................................................... 867 Reservoir......................................................................................................................................................... Input Data 868 Step by Step ......................................................................................................................................................... 868 System Options ......................................................................................................................................... 868 PVT data Input ......................................................................................................................................... 869 Saving the file ......................................................................................................................................... 870 System Equipment ......................................................................................................................................... Description 871 Deviation Survey ................................................................................................................................... 871 Surface Equipment ................................................................................................................................... 873 Dow n Hole Equipment ................................................................................................................................... 873 Geothermal gradient ................................................................................................................................... 874 Average Heat Capacities ................................................................................................................................... 876 Equipment Summary ................................................................................................................................... 876 Inflow Performance ......................................................................................................................................... Relation (IPR) 878 Estimation of the......................................................................................................................................... w ell flow rate 883 Tutorial 08: Modelling .......................................................................................................................................................... a gas w ell w ith connected pipeline 887 Statement......................................................................................................................................................... Of The Problem 887 Input Data......................................................................................................................................................... 888 Step by Step ......................................................................................................................................................... 888 Tutorial 09: Modelling .......................................................................................................................................................... a w ater injection w ell 892 Statement......................................................................................................................................................... Of The Problem 892
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PVT Input......................................................................................................................................................... Data 893 System Equipment ......................................................................................................................................................... Input Data 893 Deviation survey......................................................................................................................................... 893 Surface Equipment ......................................................................................................................................... 893 Dow n hole Equipment ......................................................................................................................................... 893 Static Geothermal ......................................................................................................................................... Gradient 894 Average Heat Capacities ......................................................................................................................................... 894 Reservoir......................................................................................................................................................... Input Data 895 Step by Step ......................................................................................................................................................... 895 System Options ......................................................................................................................................... 895 PVT data Input ......................................................................................................................................... 896 Saving the file ......................................................................................................................................... 897 System Equipment ......................................................................................................................................... Description 897 Deviation Survey ................................................................................................................................... 898 Surface Equipment ................................................................................................................................... 899 Dow n Hole Equipment ................................................................................................................................... 900 Geothermal gradient ................................................................................................................................... 901 Average Heat Capacities ................................................................................................................................... 903 Equipment Summary ................................................................................................................................... 903 Inflow Performance ......................................................................................................................................... Relation (IPR) 905 Estimation of the......................................................................................................................................... w ell injection flow rate 909 Lift Curve generation ......................................................................................................................................... for other applications 913 Introduction ................................................................................................................................... 913 Steps ................................................................................................................................... 914 Data Entry For Lift ................................................................................................................................... Curve Generation 914 Lift Curve generation ................................................................................................................................... 917 Lift Curve Inspection ................................................................................................................................... 918 Lift Curve Export ................................................................................................................................... 919 Tutorial 10: Modelling .......................................................................................................................................................... a gas injection w ell 921 Statement......................................................................................................................................................... Of The Problem 922 PVT Input......................................................................................................................................................... Data 922 System Equipment ......................................................................................................................................................... Input Data 922 Deviation survey......................................................................................................................................... 922 Surface Equipment ......................................................................................................................................... 923 Dow n hole Equipment ......................................................................................................................................... 923 Static Geothermal ......................................................................................................................................... Gradient 923 Average Heat Capacities ......................................................................................................................................... 924 Reservoir......................................................................................................................................................... Input Data 924 Step by Step ......................................................................................................................................................... 925 System Options ......................................................................................................................................... 925 PVT data Input ......................................................................................................................................... 926 Saving the file ......................................................................................................................................... 926 System Equipment ......................................................................................................................................... Description 927 Deviation Survey ................................................................................................................................... 927 Surface Equipment ................................................................................................................................... 928 Dow n Hole Equipment ................................................................................................................................... 929 Geothermal gradient ................................................................................................................................... 930 Average Heat Capacities ................................................................................................................................... 931 Equipment Summary ................................................................................................................................... 932 Inflow Performance ......................................................................................................................................... Relation (IPR) 932 Estimation of the......................................................................................................................................... w ell injection flow rate 936 Lift Curve generation ......................................................................................................................................... for gas injectors 939 Introduction ................................................................................................................................... 939 Steps ................................................................................................................................... 940
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PROSPER Data Entry For Lift ................................................................................................................................... Curve Generation 940 Lift Curve generation ................................................................................................................................... 945 Lift Curve Inspection ................................................................................................................................... 945 Lift Curve Export ................................................................................................................................... 945 Tutorial 11: Modelling .......................................................................................................................................................... a steam injection w ell 947 Statement......................................................................................................................................................... Of The Problem 947 PVT Input......................................................................................................................................................... Data 948 System Equipment ......................................................................................................................................................... Input Data 948 Deviation survey......................................................................................................................................... 948 Surface Equipment ......................................................................................................................................... 948 Dow n hole Equipment ......................................................................................................................................... 948 Static Geothermal ......................................................................................................................................... Gradient 949 Reservoir......................................................................................................................................................... Input Data 949 Step by Step ......................................................................................................................................................... 950 System Options ......................................................................................................................................... 950 PVT data Input ......................................................................................................................................... 951 System Equipment ......................................................................................................................................... Description 952 IPR Data ......................................................................................................................................... 957 Estimation of the......................................................................................................................................... w ell injection flow rate 959 Lift Curve Generation .......................................................................................................................................................... for Steam Injectors 965 Introduction ......................................................................................................................................................... 965 Steps ......................................................................................................................................................... 966 PROSPER......................................................................................................................................................... Preference Settings 966 Data Entry......................................................................................................................................................... for Lift Curve Generation 967 Lift Curve......................................................................................................................................................... Inspection 970 Lift Curve......................................................................................................................................................... Export 971 Tutorial 12: Modelling .......................................................................................................................................................... an oil w ell w ith gravel pack 973 Pre-requisite ......................................................................................................................................................... and Statement Of The Problem 973 Gravel Pack ......................................................................................................................................................... Data 974 Step by Step ......................................................................................................................................................... 974 System Options ......................................................................................................................................... 974 Inflow Performance ......................................................................................................................................... Relation (IPR) 975 Estimation of the......................................................................................................................................... w ell flow rate 978 Tutorial 13: Modelling .......................................................................................................................................................... a frac and packed w ell 982 Pre-requisite ......................................................................................................................................................... and Statement Of The Problem 982 Frac & Pack ......................................................................................................................................................... Data 982 Step by Step ......................................................................................................................................................... 983 System Options ......................................................................................................................................... 983 Inflow Performance ......................................................................................................................................... Relation (IPR) 984 Estimation of the......................................................................................................................................... w ell flow rate 989 Tutorial 14: Modelling .......................................................................................................................................................... a w ell w ith Pre-Packed Screen 993 Pre-requisite ......................................................................................................................................................... and Statement Of The Problem 993 Pre-packed ......................................................................................................................................................... Screen Data 993 Step by Step ......................................................................................................................................................... 994 System Options ......................................................................................................................................... 994 Inflow Performance ......................................................................................................................................... Relation (IPR) 995 Estimation of the......................................................................................................................................... w ell flow rate 997 Tutorial 15: .......................................................................................................................................................... Modelling a w ell w ith slotted liners 1001 Pre-requisite ......................................................................................................................................................... and Statement Of The Problem 1001 Slotted Liner ......................................................................................................................................................... Data 1001 Step by ......................................................................................................................................................... Step 1002 System Options......................................................................................................................................... 1002 Inflow Performance ......................................................................................................................................... Relation (IPR) 1003 Estimation of the ......................................................................................................................................... w ell flow rate 1005
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Tutorial 16: .......................................................................................................................................................... Modelling a w ell w ith Wire Wrapped Screen 1009 Pre-requisite ......................................................................................................................................................... and Statement Of The Problem 1009 Wire Wrapped ......................................................................................................................................................... Screen Data 1009 Step by ......................................................................................................................................................... Step 1010 System Options......................................................................................................................................... 1010 Inflow Performance ......................................................................................................................................... Relation (IPR) 1011 Estimation of the ......................................................................................................................................... w ell flow rate 1012 Tutorial 17: .......................................................................................................................................................... Fully com postional w ell m odel for retrograde condenssate 1016 Statement ......................................................................................................................................................... Of The Problem 1016 PVT Input ......................................................................................................................................................... Data 1017 System Equipment ......................................................................................................................................................... Input Data 1018 Deviation survey ......................................................................................................................................... 1018 Surface Equipment ......................................................................................................................................... 1018 Dow n hole Equipment ......................................................................................................................................... 1018 Static Geothermal ......................................................................................................................................... Gradient 1018 Average Heat Capacities ......................................................................................................................................... 1019 Reservoir ......................................................................................................................................................... Input Data 1019 Step by ......................................................................................................................................................... Step 1020 System Options......................................................................................................................................... 1020 PVT data Input......................................................................................................................................... 1022 Saving the file ......................................................................................................................................... 1024 System Equipment ......................................................................................................................................... Description 1024 Deviation Survey ................................................................................................................................... 1025 Surface Equipment ................................................................................................................................... 1026 Dow n Hole Equipment ................................................................................................................................... 1027 Geothermal gradient ................................................................................................................................... 1028 Average Heat................................................................................................................................... Capacities 1029 Equipment Summary ................................................................................................................................... 1030 Saving the PROSPER ................................................................................................................................... file 1032 Inflow Performance ......................................................................................................................................... Relation (IPR) 1032 Estimation of the ......................................................................................................................................... w ell flow rate 1036 Tutorial 18: .......................................................................................................................................................... Fully com postional CO2 injection w ell 1040 Statement ......................................................................................................................................................... Of The Problem 1040 PVT Input ......................................................................................................................................................... Data 1041 System Equipment ......................................................................................................................................................... Input Data 1041 Deviation survey ......................................................................................................................................... 1042 Surface Equipment ......................................................................................................................................... 1042 Dow n hole Equipment ......................................................................................................................................... 1042 Static Geothermal ......................................................................................................................................... Gradient 1042 Reservoir ......................................................................................................................................................... Input Data 1043 Step by ......................................................................................................................................................... Step 1044 System Options......................................................................................................................................... 1044 PVT data Input......................................................................................................................................... 1046 Saving the file ......................................................................................................................................... 1048 System Equipment ......................................................................................................................................... Description 1048 Deviation Survey ................................................................................................................................... 1048 Surface Equipment ................................................................................................................................... 1050 Dow n Hole Equipment ................................................................................................................................... 1050 Geothermal gradient ................................................................................................................................... 1051 Equipment Summary ................................................................................................................................... 1053 Inflow Performance ......................................................................................................................................... Relation (IPR) 1054 Estimation of the ......................................................................................................................................... w ell flow rate 1058 Tutorial 19: .......................................................................................................................................................... Matching a dry gas w ell test 1062 Statement ......................................................................................................................................................... Of The Problem 1062
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PROSPER Well Test......................................................................................................................................................... data 1063 Step by ......................................................................................................................................................... Step 1063 Open the PROSPER ......................................................................................................................................... file 1063 Resetting any previous ......................................................................................................................................... VLP matching 1064 Matching - VLP......................................................................................................................................... /IPR Quality Check 1065 Well Test Data................................................................................................................................... Entry 1066 Estimate the U-value ................................................................................................................................... 1067 Correlation Comparison ................................................................................................................................... 1068 VLP matching................................................................................................................................... 1071 VLP / IPR matching ................................................................................................................................... 1073 Performing Sensitivity ................................................................................................................................... runs 1075 Tutorial 20: .......................................................................................................................................................... Matching a naturally flow ing oil w ell test 1080 Statement ......................................................................................................................................................... Of The Problem 1080 PVT Lab......................................................................................................................................................... data & Well Test data 1081 Step by ......................................................................................................................................................... Step 1082 Open the PROSPER ......................................................................................................................................... file 1082 Resetting any previous ......................................................................................................................................... VLP matching 1082 PVT matching ......................................................................................................................................... 1083 Matching - VLP......................................................................................................................................... /IPR Quality Check 1087 Well Test Data................................................................................................................................... Entry 1088 Estimate the U-value ................................................................................................................................... 1089 Correlation Comparison ................................................................................................................................... 1090 VLP matching................................................................................................................................... 1094 VLP / IPR matching ................................................................................................................................... 1095 Performing Sensitivity ................................................................................................................................... runs 1101 Tutorial 21: .......................................................................................................................................................... Matching a w ater injection w ell test 1106 Statement ......................................................................................................................................................... Of The Problem 1106 Well Test......................................................................................................................................................... data 1106 Step by ......................................................................................................................................................... Step 1107 Open the PROSPER ......................................................................................................................................... file 1107 Resetting any previous ......................................................................................................................................... VLP matching 1107 PVT matching ......................................................................................................................................... 1108 Matching - VLP......................................................................................................................................... /IPR Quality Check 1109 Well Test Data................................................................................................................................... Entry 1110 Estimate the U-value ................................................................................................................................... 1111 Correlation Comparison ................................................................................................................................... 1112 VLP matching................................................................................................................................... 1114 VLP / IPR matching ................................................................................................................................... 1116 Performing Sensitivity ................................................................................................................................... runs 1119 Tutorial 22: .......................................................................................................................................................... Matching a gas injection w ell test 1123 Statement ......................................................................................................................................................... Of The Problem 1123 PVT Lab......................................................................................................................................................... data & Well Test data 1124 Step by ......................................................................................................................................................... Step 1124 Open the PROSPER ......................................................................................................................................... file 1125 Resetting any previous ......................................................................................................................................... VLP matching 1125 PVT matching ......................................................................................................................................... 1126 Matching - VLP......................................................................................................................................... /IPR Quality Check 1126 Well Test Data................................................................................................................................... Entry 1127 Estimate the U-value ................................................................................................................................... 1128 Correlation Comparison ................................................................................................................................... 1129 VLP matching................................................................................................................................... 1131 VLP / IPR matching ................................................................................................................................... 1133 Performing Sensitivity ................................................................................................................................... runs 1134 Tutorial 23: .......................................................................................................................................................... Continuous Gas Lift Design 1137
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Statement ......................................................................................................................................................... of the Problem 1138 Input Data ......................................................................................................................................................... For Continuous GL design 1138 PVT Data ......................................................................................................................................... 1138 Reservoir Data......................................................................................................................................... for GL design 1138 Equipment Data......................................................................................................................................... 1138 Gas Lift design......................................................................................................................................... parameters 1138 Step by ......................................................................................................................................................... step procedure 1140 Defining the options ......................................................................................................................................... 1140 Description of the ......................................................................................................................................... gas lift PVT 1141 Description of the ......................................................................................................................................... IPR 1142 Description of the ......................................................................................................................................... Gas Lift Design Conditions 1144 Performing the......................................................................................................................................... gas lift design 1147 Transferring the ......................................................................................................................................... valve depths 1150 System Calculation ......................................................................................................................................... for a gas-lifted w ell 1151 Tutorial 24: .......................................................................................................................................................... Interm ittent Gas Lift design 1155 Introduction ......................................................................................................................................................... to intermittent Gas Lift 1155 Statement ......................................................................................................................................................... of the problem 1155 Step by ......................................................................................................................................................... step procedure 1157 Setting up the PROSPER ......................................................................................................................................... model 1157 Design of the intermittent ......................................................................................................................................... gas lift 1168 Constant Surface ......................................................................................................................................... Closing Pressure design 1169 OptiFlow Gas Lift ......................................................................................................................................... Valve Design method 1172 Tutorial 25: .......................................................................................................................................................... Coiled Tubing Gas Lift Design 1173 Statement ......................................................................................................................................................... of the Problem 1174 Input Data ......................................................................................................................................................... For Continuous GL design w ith Coiled Tubing 1174 PVT Data ......................................................................................................................................... 1174 Reservoir Data......................................................................................................................................... for GL design 1174 Equipment Data......................................................................................................................................... 1175 Coiled Tubing Gas ......................................................................................................................................... Lift design parameters 1175 Step by ......................................................................................................................................................... step procedure 1176 Defining the options ......................................................................................................................................... 1176 Gas lift PVT and ......................................................................................................................................... CT Data 1177 Description of the ......................................................................................................................................... IPR 1178 Description of the ......................................................................................................................................... CT Gas Lift Design Conditions 1179 Performing the......................................................................................................................................... CT gas lift design 1181 Fixing the CT injection ......................................................................................................................................... depth 1183 System Calculation ......................................................................................................................................... for a CT gas-lifted w ell 1184 Tutorial 26: .......................................................................................................................................................... ESP Design 1188 Statement ......................................................................................................................................................... of the Problem 1188 Input Data ......................................................................................................................................................... For ESP design 1188 PVT Data ......................................................................................................................................... 1188 Reservoir Data......................................................................................................................................... for ESP design 1189 Equipment Data......................................................................................................................................... 1189 ESP design parameters ......................................................................................................................................... 1189 Step by ......................................................................................................................................................... step procedure 1190 Defining the options ......................................................................................................................................... 1190 Description of the ......................................................................................................................................... w ell dow n hole equipment 1191 Description of the ......................................................................................................................................... IPR 1191 Description of the ......................................................................................................................................... ESP Design Conditions 1193 Performing the......................................................................................................................................... ESP design 1194 System Calculation ......................................................................................................................................... for an ESP-lifted w ell 1197 Notes on system ......................................................................................................................................... plot (VLP+IPR) for ESP-lifted w ells 1203 Tutorial 27: .......................................................................................................................................................... Design of an Hydraulic Dow nhole Pum p for an oil w ell 1207 Statement ......................................................................................................................................................... of the Problem 1207
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PROSPER Input Data ......................................................................................................................................................... For HSP design 1208 Produced Fluid......................................................................................................................................... & Pow er Fluid PVT Data 1208 Reservoir Data......................................................................................................................................... for HSP design 1208 Equipment Data......................................................................................................................................... 1208 HSP design parameters ......................................................................................................................................... 1208 Step by ......................................................................................................................................................... step procedure 1209 Defining the options ......................................................................................................................................... 1209 Produced Fluid......................................................................................................................................... & Pow er Fluid PVT Data 1210 Description of the ......................................................................................................................................... w ell dow n hole equipment 1211 Description of the ......................................................................................................................................... IPR 1212 HSP Design ......................................................................................................................................... 1214 Tutorial 28: .......................................................................................................................................................... Sucker Rod Pum p Design 1219 Statement ......................................................................................................................................................... of the Problem 1220 Input Data ......................................................................................................................................................... for SRP-Design 1220 Fluid Properties......................................................................................................................................... 1220 Equipment Data......................................................................................................................................... 1220 Deviation Survey ................................................................................................................................... 1220 Surface Equipment ................................................................................................................................... 1220 Dow nhole Equipment ................................................................................................................................... 1220 Geothermal Gradient ................................................................................................................................... 1221 Average Heat................................................................................................................................... Capacities 1221 Inflow Performance ......................................................................................................................................... Relation 1221 SRP-Design parameters ......................................................................................................................................... 1221 Step by ......................................................................................................................................................... step SRP design 1222 Options ......................................................................................................................................... 1223 PVT Data: Input......................................................................................................................................... & Matching 1223 System Equipment ......................................................................................................................................... 1227 SRP Data ......................................................................................................................................... 1231 Inflow Performance ......................................................................................................................................... Data 1233 SRP Design ......................................................................................................................................... 1238 Running......................................................................................................................................................... sensitivities w ith a SRP-lifted w ell model 1241 Tutorial 29: .......................................................................................................................................................... Progressive Cavity Pum p (PCP) Design 1243 Statement ......................................................................................................................................................... of the Problem 1243 Adding a......................................................................................................................................................... PCP to the pump database 1244 Adding a......................................................................................................................................................... Sucker Rod to the database 1246 Input Data ......................................................................................................................................................... for PCP-Design 1248 Fluid Properties......................................................................................................................................... 1248 Well Equipment......................................................................................................................................... Data 1248 Deviation Survey ................................................................................................................................... 1248 Surface Equipment ................................................................................................................................... 1249 Dow nhole Equipment ................................................................................................................................... 1249 Geothermal Gradient ................................................................................................................................... 1249 Average Heat................................................................................................................................... Capacities 1249 Inflow Performance ......................................................................................................................................... Relation 1249 PCP-Design parameters ......................................................................................................................................... 1250 Step by ......................................................................................................................................................... step procedure 1250 PROSPER Well......................................................................................................................................... model set-up 1250 PCP Design procedure ......................................................................................................................................... 1259 PCP sensitivity ......................................................................................................................................... calculation 1261 Tutorial 30: .......................................................................................................................................................... Modelling Diluent Injection into an oil w ell 1266 Statement ......................................................................................................................................................... of the Problem 1266 Input Data ......................................................................................................................................................... 1267 Produced Fluid......................................................................................................................................... & Diluent PVT 1267 Well Equipment......................................................................................................................................... Data 1268
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Inflow Performance ......................................................................................................................................... Data 1269 Diluent Injection......................................................................................................................................... Data 1269 Step by ......................................................................................................................................................... step procedure 1269 PROSPER Well......................................................................................................................................... model set-up 1269 Calculating ......................................................................................................................................................... Sensitivites 1280 Tutorial 31: .......................................................................................................................................................... Modelling Multiphase Pum p w ith PROSPER 1284 Statement ......................................................................................................................................................... of the Problem 1284 Model Set ......................................................................................................................................................... Up 1285 Calculating ......................................................................................................................................................... Sensitivies 1291 Tutorial 32: .......................................................................................................................................................... Trouble-shooting a gas lifted w ell 1295 Statement ......................................................................................................................................................... Of The Problem 1295 Input Data ......................................................................................................................................................... 1296 PROSPER w ell......................................................................................................................................... model 1296 Well test results ......................................................................................................................................... for Quicklook 1296 Gas Lift Valves......................................................................................................................................... Data 1297 Step by ......................................................................................................................................................... Step Procedure 1297 Tutorial 33: .......................................................................................................................................................... Trouble-shooting an ESP-lifted w ell 1309 Statement ......................................................................................................................................................... Of The Problem 1309 Well Test......................................................................................................................................................... Data 1310 Strategy......................................................................................................................................................... 1310 Phase 1: Build ......................................................................................................................................... a PROSPER model 1310 Phase 2: Collect ......................................................................................................................................... and analyse w ell test data 1310 Phase 3: Analyse ......................................................................................................................................... and match test to w ell model 1312 Phase 4: Use model ......................................................................................................................................... to run w hat-if scenarios 1316 Tutorial 34: .......................................................................................................................................................... Trouble-shooting an HSP-lifted w ell 1320 Statement ......................................................................................................................................................... Of The Problem 1320 Well Test......................................................................................................................................................... Data 1320 Strategy......................................................................................................................................................... 1321 Phase 1: Build ......................................................................................................................................... a PROSPER model 1321 Phase 2: Collect ......................................................................................................................................... and analyse w ell test data 1321 Phase 3: Analyse ......................................................................................................................................... and match test to w ell model 1322 Tutorial 35: .......................................................................................................................................................... Trouble-shooting a SRP-lifted w ell 1329 Tutorial 36: .......................................................................................................................................................... Flow assurance calculations 1330 Statement ......................................................................................................................................................... Of The Problem 1331 Input Data ......................................................................................................................................................... 1331 Step by ......................................................................................................................................................... step procedure 1338 Tutorial 37: .......................................................................................................................................................... Pipeline Only Modelling & m atching 1359 Statement ......................................................................................................................................................... Of The Problem 1360 Input Data ......................................................................................................................................................... 1360 Fluid PVT data ......................................................................................................................................... 1360 Pipeline Data ......................................................................................................................................... 1360 Flow test results ......................................................................................................................................... 1361 Step by ......................................................................................................................................................... step procedure 1362 PROSPER Model ......................................................................................................................................... Setup 1362 Pipe Performance ......................................................................................................................................... Matching 1371 Sensitivity runs......................................................................................................................................... 1378 Tutorial 38: .......................................................................................................................................................... Full enthalpy balance tutorial 1384 Statement ......................................................................................................................................................... Of The Problem 1384 Input Data ......................................................................................................................................................... 1385 PVT Data ......................................................................................................................................... 1385 Equipment Data......................................................................................................................................... 1385 Deviation Survey ................................................................................................................................... 1385 Surface Equipment ................................................................................................................................... 1385 Dow nhole Equipment ................................................................................................................................... 1386
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PROSPER Temperature Data ................................................................................................................................... 1386 Drilling and Completion ................................................................................................................................... Data 1386 Lithology ................................................................................................................................... 1387 Databases for................................................................................................................................... thermal properties 1387 Reservoir Data......................................................................................................................................... 1387 Step by ......................................................................................................................................................... Step procedure 1388 PROSPER Model ......................................................................................................................................... Setup 1388 System Calculation ......................................................................................................................................... 1402 Tutorial 39: .......................................................................................................................................................... Im proved Approxim ation 1405 Statement ......................................................................................................................................................... Of The Problem 1405 Input Data ......................................................................................................................................................... 1406 PVT Data ......................................................................................................................................... 1406 Equipment Data......................................................................................................................................... 1406 Deviation Survey ................................................................................................................................... 1406 Surface Equipment ................................................................................................................................... 1406 Dow nhole Equipment ................................................................................................................................... 1406 Temperature Data ................................................................................................................................... 1407 Reservoir Data......................................................................................................................................... 1407 Step by ......................................................................................................................................................... Step procedure 1408 PROSPER Model ......................................................................................................................................... Setup 1408 System Calculation ......................................................................................................................................... 1418 Tutorial 40: .......................................................................................................................................................... SPOT tutorial 1421 Statement ......................................................................................................................................................... Of The Problem 1421 PVT Input ......................................................................................................................................................... Data 1422 System Equipment ......................................................................................................................................................... Input Data 1422 Deviation survey ......................................................................................................................................... 1422 Surface Equipment ......................................................................................................................................... 1422 Dow n Hole Equipment ......................................................................................................................................... 1422 Static Geothermal ......................................................................................................................................... Gradient 1423 Average Heat Capacities ......................................................................................................................................... 1423 Reservoir ......................................................................................................................................................... Input Data 1423 Step by ......................................................................................................................................................... Step 1426 System Options......................................................................................................................................... 1426 PVT data Input......................................................................................................................................... 1427 Saving the PROSPER ......................................................................................................................................... file 1428 System Equipment ......................................................................................................................................... Description 1428 Deviation Survey ................................................................................................................................... 1429 Surface Equipment ................................................................................................................................... 1430 Dow n Hole Equipment ................................................................................................................................... 1431 Geothermal gradient ................................................................................................................................... 1432 Average Heat................................................................................................................................... Capacities 1433 Equipment Summary ................................................................................................................................... 1434 Saving the PROSPER ................................................................................................................................... file 1436 Inflow Performance ......................................................................................................................................... Relation (IPR) 1436 Estimation of the ......................................................................................................................................... w ell flow rate 1450 Comparison of ......................................................................................................................................... different Gun Systems 1454 Inspection of SPOT ......................................................................................................................................... results at log- scale 1458 Tutorial 41: .......................................................................................................................................................... Multi-Zones Com pletion using m ultilayer IPR 1468 Statement ......................................................................................................................................................... of the problem 1468 Input Data ......................................................................................................................................................... 1469 Modelling......................................................................................................................................................... Strategy 1471 Step by ......................................................................................................................................................... Step Procedure 1471 Tutorial 42: .......................................................................................................................................................... Multi-Zones Com pletion using m ultilateral IPR 1486 Statement ......................................................................................................................................................... of the problem 1486
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Input Data ......................................................................................................................................................... 1486 Modelling......................................................................................................................................................... Strategy 1488 Step by ......................................................................................................................................................... Step Procedure 1489 Tutorial 43: .......................................................................................................................................................... Jet Pum p Design 1520 Statement ......................................................................................................................................................... Of the Problem 1521 Input Data ......................................................................................................................................................... 1521 Jet Pump......................................................................................................................................................... Design Strategy 1523 Step by ......................................................................................................................................................... Step Procedure to design a jet pump 1523 Tutorial 44: .......................................................................................................................................................... Black oil Condensate Model Validation in PROSPER 1537
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1
Technical Overview
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2
Technical Overview This technical overview contains a summary list of the major technical capabilities of PROSPER. The capabilities can be divided in the following disciplines: · Fluid modelling (PVT) · Inflow (IPR) and sand control options · Well bore and pipeline hydraulics (VLP) · Artificial lift options · Flow assurance and advanced thermal options · What's New · Examples Guide
1.1
Fluid modelling options PROSPER offers both existing fluid modelling options. Fluid can be modelled with the traditional "black oil" approach or a fully compositional approach. PROSPER offers black oil models for: · dry and wet gas · oil and water (heavy oil, "black oil", volatile oils, ...) · retrograde condensate For all types of fluids, the user can: · use existing black oil correlations · calibrate and validate lab measurements against black oil correlations · use PVT look-up tables over the expected operating pressure and temperature conditions. Beside the black oil models, the two majors Equation Of State models used in the oil industry (Peng-Robinson and Soave Redlich Kwong) are implemented in PROSPER allowing fully compositional modelling. Users can embed their own proprietary EOS models into PROSPER via Dynamic Link Library. The format of the DLL can be provided at request. Hydrate and wax calculations can be performed with compositional fluid models. When using black oil models, hydrate curves can be imported from any other application like PVTp, the thermodynamics package developed by Petroleum Experts. There is a flag that can be activated whenever calculated operating conditions falls © 1990-2011 Petroleum Experts Limited
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PROSPER
within the hydrates formation region. PROSPER can model steam injection and steam production. A steam table calculator is available. Further options in PROSPER are: · Non-Newtonian fluids, · DLL for proprietary fluid viscosity model for Non-Newtonian fluids · Emulsion models ç Back to Overview
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4
Inflows and Sand Control options More than two dozens of inflow / combination of inflow models exist in PROSPER that can be selected for different configurations: · · · · · · · · · · · · ·
straight open or cased hole slanted well partially perforated well horizontal well (with and without friction loss) horizontal well with transverse vertical fracture multi-zone completions for stacked reservoirs with possible cross-flow and pressure loss between the zones multi-lateral well and smart well well of any geometry like snaky or U-shaped wells Hydraulically fractured well Well in dual-porosity reservoirs (naturally fractured) water and gas injection wells water injector with thermally induced fractures External entry with User-entered IPR look-up tables
Various skin models are currently available: · Locke Skin model · MacLeod Skin model · Karakas & Tariq · Cinco-Ley and Martig-Bronz (I & II) · Wong-Clifford · SkinAide (Elf) · SPOT (Shell) A DLL template exists that allow User to import proprietary IPR and skin models into PROSPER. The following sand control options are available in PROSPER: · Gravel Pack · Pre-Packed screen, · Wire-wrapped screen and · Slotted liners Further inflow-related models available in PROSPER are: · Mobility correction using relative permeability · Vogel correction · Permeability reduction due to rock compaction · Advanced perforation modelling capabilities with integrated tubing / casing and gun system databases · Gas coning with matching © 1990-2011 Petroleum Experts Limited
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PROSPER
· analytical coning model for water, gas and gas + water for horizontal wells (see horizontal well with dP friction) ç Back to Overview
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Technical Overview
1.3
6
Well bore and Pipeline hydraulics Nearly two dozens of multiphase correlations are available to the PROSPER user. The flexible architecture of the software gives any User the opportunity to add any number of proprietary multiphase correlations via DLL. The format of the DLL can be provided at request. Internal research have led to the development of a series of very successful multiphase correlations that have become benchmark in the industry today. In particular when compared to actual measurements, the Petroleum Experts 2 correlation has given excellent results in a wide range of situations: vertical well, horizontal well, deviated well, large diameter well,oil wells, gas and retrograde condensate wells, .. When calculating the pressure drop in a well bore or a pipeline, PROSPER offers the option to switch from one starting multiphase correlation to another one depending upon the well or pipe inclination. PROSPER can handle any combination of flow paths: annular flow only, tubular flow only, simultaneous annular and tubular flow, sequences of tubular and annular flow or sequences of mixed flow and tubular or annular flow. ç Back to Overview
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1.4
PROSPER
Artificial lift systems The following artificial lift options are available in PROSPER: · Continuous gas lift · Intermittent gas lift · Coiled Tubing gas lift · Electrical Submersible Pumps (ESP) · Hydraulic Downhole Pumps (HSP) with Commingled Annular Supply · Hydraulic Downhole Pumps (HSP) with Commingled Tubing Supply · Hydraulic Downhole Pumps (HSP) with Closed Loop Supply · Progressive Cavity Pumps (PCP) with Sucker Rod Drive · Progressive Cavity Pumps (PCP) with Down Hole Motor Drive · Diluent Injection (Annular Injection - Tubing Production) · Diluent Injection (Tubing Injection - Annular Production) · Jet Pump (Annular Injection - Tubing Production) · Jet Pump (Tubing Injection - Annular Production) · Multiphase Pumps (Framo Pumps) ç Back to Overview
PROSPER Manual
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Technical Overview
1.5
8
Flow assurance Advanced thermal models and miscellaneous options are available in PROSPER for flow assurance features studies.
1.5.1 Advanced Thermal Models
For advanced thermal modelling, the user can select the Enthalpy balance model or the improved approximation. The enthalpy balance is a rigorous thermal model that accounts for convection, radiation and conduction. Joule-Thompson effects are accounted for. Another advanced thermal model is the "improved approximation" which is also a full enthalpy balance model with the following difference when compared with the enthalpy balance: In the improved approximation, the heat term is calculated with a variable User-entered overall heat transfer coefficient whereas the heat transfer coefficient in the full enthalpy balance model is calculated internally.
1.5.2 General Flow Assurance Features Beside the advanced thermal models, the following options are available in PROSPER for flow assurance studies: · hydrate and wax appearance prediction models · Solid Transportation models · Erosional velocity calculation with clean fluid or sand laden fluid · Liquid loading calculations · Pigging calculation: pigged slug length, pigged slug volume, pigged slug production time and pigged slug residency time · Taitel-Dukler flow regime map along pipeline length with severe-slugging region (with and without Barnea criteria) · Detailed output for slug and bubble calculations: mean slug length, mean bubble length, slug frequency, Slug and bubble surge factor, ... ç Back to Overview
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1.6
PROSPER
What's New This is a list of enhancements to Prosper for each new Version released. Version 11.5 This is a summary of the main additions that have been incorporated into the PROSPER program since the 2009 official release. · Improved CO2 modeling
PVT Modeling
· Condensed Water Vapour with Retrograde Condensate · Condensed water vapour can be modeled with gas retrograde condensate fluid · Improved Black Oil Retrograde Condensate Model · Changes applied to improve consistency of the black oil model at the boundaries of its applicability for oil and condensate systems · HSP · Addition of Pump Speed Method (Entered or Calculated) in Quicklook, Gradient and VLP calculations. It is now possible to use the program to calculate the pump/turbine speed in order to operate the pump at the highest efficiency · ESP pump database · Complete CENTRILIFT Pump Database implemented
Artificial Lift
· Gas lift Quicklook · Added the possibility to enter DeRating parameters for Thornhill/Craver to correct the dP through the orifice for actual performance · ESP VLP/IPR matching · The VLP/IPR matching for ESP allows to enter the pump intake and discharge pressures as inputs. These data can then be passed over to the Quicklook for detailed analysis of the pump performance
Calculations
· Reset results · An option to erase the results of any calculation previously performed has been added · Gradient Summary Chart
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Technical Overview
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· In the Tubing Correlation and Pipeline Correlation Comparison a Summary section allows the user to compare the pressure drops and the components of the pressure drops of the selected multiphase flow correlations and mechanistic models · Solids Plot · Critical Transport velocities plot is now available after running any calculation by accessing the Options button · Export option in PVT section · In the main PVT section an export facility has been added to allow the used to export input (Input Data, Match data tables, Tables) and output (correlation parameters, PVT calculations) Export/Import
· Export/Import option in IPR External Entry · The External Entry IPR can be exported/imported from the IPR section · Clip to Copy and Paste data in PVT section · The Clip buttons in the PVT Match Data and Tables sections now allow the user to copy and paste data from/to the Clipboard to facilitate data import/export · Improved IPR Validation Error Messages · More information are reported when a validation error is triggered
Program Interface
· IPR test data enhancement · In the IPR plot Test Data it is now possible to enter a date stamp and a comment for each entered test · File Overwrite check · Possibility to switch on/off a confirmation message when an existing file is overwritten · New OS Commands: PROSPER.RESET
Reset some or all of the data RESET(ALL) RESET(PVT) RESET(SIN) RESET(ANL) RESET(OUT)
PROSPER.PVT.IMPORT
Import PVTP file in PVT Tables or Match sections
OpenServer
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PROSPER
PROSPER.ANL.VMT. VLPIPR
Perform the VLP/IPR Matching VLP/IPR Command
PROSPER.ANL.VMT. ADJUSTCALC
Adjust Calculate PROSPER.ANL.VMT. ADJUSTCALC(i) - for test i (if i=0 then does all tests)
PROSPER.ANL.VMT. ADJUSTPI
Adjust PI PROSPER.ANL.VMT.ADJUSTPI(i) - for test i (if i=0 then does all tests)
PROSPER.ANL.VMT. ADJUSTPRES
Adjust Pres PROSPER.ANL.VMT. ADJUSTPRES(i) - for test i (if i=0 then does all tests)
PROSPER.ANL.VMT. ADJUSTRESET
Reset Adjust Data & Results PROSPER.ANL.VMT. ADJUSTRESET(type,i) - for test i (if i=0 then does all tests) type=1 Reset Amended PI type=2 Reset Amended PRES type=3 Calculated FBHP type=4 Heat Transfer Coefficient type=5 Calculated Results type=6 Reset ALL
PROSPER.MENU.FILE. OPEN
Menu Command - File Open
PROSPER.MENU.FILE. SAVEAS
Menu Command - File Save As
PROSPER.MENU.ANL. RESET
Menu Command - Calculation Reset Results
Version 11.0 This is a summary of the main additions that have been incorporated into the PROSPER program since the 2008 official release.
Inflow
PROSPER Manual
· SPOT(Shell Perforation Optimisation Tool) is an IPR calculator developed originally by Shell. Its main unique features are:· Modelling of different perforating guns selected from a guns database covering all the major vendors. · Corrects gun test data such as DoP (Depth of
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Technical Overview
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penetrationG and EHD (Entry Hole Diameter) to reservoir conditions. · Log data can be used to model vertical differences in reservoir parameters such as permeability, porosity and rock strength. · Model to predict sanding. · Several invasion models. · Models reperforation jobs/workovers. This has been implemented in PROSPER as a new IPR model. The correction of test DoP and EHD to reservoir conditions is also available for existing PROSPER IPR models. · Sand Control Previously the only option for sand control in Prosper was Gravel Pack. The following options have now been added · Pre Packed Screen · Wire Wrapped Screen · Slotted Liner Both the Darcy and Non-Darcy effects are modelled for the screen/liner and any material between the formation and screen/ liner · Sand Production (Failure) Sand Production can be caused by increasing stress near the well bore resulting from reservoir depletion. The economic impact of the result is significant both in terms of completion costs (implementing sand control) and the number of development wells (because of the lower productivity associated with sand control). Prediction of the maximum possible drawdown before sand production can therefore be important in field development. The aim of this model is to calculate the drawdown at which sand production can be expected. Stress can be estimated either – · From depth and reservoir pressure · From a specified stress · From specified stress gradients and depths · From assumptions if no stress data available · Inflow MultiLayer Models · Automatic transfer of model from Prosper to GAP · Pseudo Pressure table per layer for Gas/Condensate models § Increases accuracy in cases when layer PVT properties are significantly different · Ability to sensitize on Layer PVT properties in System calculation Sensitivity
· Following new variables are available : · Perforating Gun (SPOT)
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PROSPER
· · · ·
Tubing Description Casing Description Injection Fluid Temperature Multi Layer PVT Parameters
· Sensitivity Data Export · Sensitivity Generate Options · Perforating Gun Database · Provided by Shell as part of SPOT · Updated and verified by PE in conjunction with the manufacturers 1) Baker 2) DYNA 3) ETA 4) Halliburton 5) Schlumberger 6) Owen 7) INNICOR 8) Titan 9) GeoDynamics 10) CCP
Databases
· Tubing Database § Available for the following manufacturers 1) Benoit Machine 2) FiberGlass Systems 3) Grant Prideco 4) Halliburton Energy Services 5) Hunting Energy Services 6) JFE Steel 7) Metal One Corp 8) Tenaris Hydril 9) TPS Technitube Rohrenwerke 10) VAM · Casing Database Available for the following manufacturers 1) Centron International Inc. 2) Dalmine Spa 3) Equivalent S.A. 4) FiberGlass Systems 5) Frank's International 6) GB Connections 7) Grant Prideco (Atlas Bradford) 8) HSC Corp 9) Hunting Energy Services 10) Hydril 11) JFE Steel / Hunting Oilfield
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12) Mannesmann 13) Nippon Steel Corp 14) NKK Corp 15) Sidera S.A.I.C. 16) Smith FiberGlass products Inc. 17) Star FiberGlass Systems 18) Tenaris 19) TPS Technitube Rohrenwerke 20) Tubular FiberGlass Corp 21) VAM 22) XL Systems Inc. · Pipe Schedule Access to the tubing and casing database will also be available from the equipment date entry screens · Rigorous modelling of CO2 Injection when combined with
PVT Section
EoS · Lumping-DeLumping large compositions § Paired large and small(lumped) compositions with same phase behaviour and surface properties · Sour Gas Modelling § Originally created to model CO2 rich compositions. § Now improved and extended to other similar mixtures – CO2, · · · · ·
VLP / IPR Matching
Lift
H2S, C1 etc Egbogah Viscosity Correlation Bergman-Sutton Viscosity Correlation Al Marhoun Correlation for Pb, Rs, Bo and Viscosity Injection of Non-Newtonian Fluids (Polymers etc) Interpolation warnings for Bg
· Estimated Heat Transfer Coefficient options § We can now transfer the estimated U value (or average of estimated U values) directly into the geothermal gradient · Estimation of Reservoir Parameters from Match Point data § Many users have used the VLP/IPR Matching section and its easy access to the Inflow section to adjust reservoir parameters in order to find a solution that corresponded to the measured data in the VLP Match record. Thus they were able to track changes in Reservoir Pressure and P.I. Improvements in IPM6 meant that this process had become slightly more long winded. This can now be done automatically in Prosper in IPM7 o Estimation of Reservoir Pressure o Estimation of PI from (Only if IPR – PI method selected) · Multi Variable SYSTEM & VLP commands © 1990-2011 Petroleum Experts Limited
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PROSPER
Curves
· Mass and Molar Rate Entry § Independent of separation process § Mass Rates available for Black Oil & EOS models § Molar Rate only for EOS · Eclipse § Generation of files compatible with E300 § Molecular weight & Water Molar Fraction as sensitivity variables Intermittent Gas Lift Design Spacing Line Design Methodology Stability Criteria for Gas Lift Lift Gas Gradient available on gradient calculation screens Valve Performance Clearinghouse § VPC in Gas Lift Design & QuickLook § VPC Options in Preferences · Hydraulic Submersible Pump § Improved sensitivity modelling § Automatic step size reduction. · Electrical Submersible Pump § Addition of complete Centrilift Pump & Motor catalogue § Automatic step size reduction. · SRP § Calculation of Stroke Size from Liquid Rate improved § Improved error reporting & database export. · · · · ·
Artificial Lift
OpenServer
· New OS Commands · ANL.SYM.CALC Perform the System Sensitivity Calculation (Multi Variables) · ANL.SYM.GENRATES Generate Rates for the System Sensitivity Calculation (Multi Variables) · ANL.SYM.EXPORT Export Lift Curves Generated by the System Sensitivity Command (Multi Variables) · ANL.VLM.CALC Perform the VLP (Multi Variable) Sensitivity Command · ANL.VLM.GENRATES Generate Rates for the VLP (Multi Variable) Sensitivity Command · ANL.VLM.EXPORT Export Lift Curves Generated by the VLP (Multi Variable) Sensitivity Command · ANL.GLI.CALC Perform the Intermittent Gas lift Design · New OS Functions · ANL.NODES.MSD Returns The Measured Depth Of The ith Node (PROSPER.ANL.NODES.MSD[i]) · ANL.NODES.TVD Returns The True Vertical Depth Of The ith Node (PROSPER.ANL.NODES.TVD[i])
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Technical Overview
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· Evaluation Button on Open Server Screen
Miscellaneous
· · · · · · · · ·
WHPtoBHP – to include surface equipment Hydro3P flow correlation updated Hydro Choke Model updated Improved handling of OLGAS licences Improved Flow Correlation Information Plots in Deviation Survey Plotting Improvements Tubing and Pipe drawings Improved Free Format number option
Version 10.0 This is a summary of the main additions that have been incorporated into the PROSPER program since the 2007 official release. Steam Model in PVT to enable modelling of Steam Injector Wells Additional Artificial Lift Method to enable the design and modelling of wells produced using Sucker Rod Pumps The Enthalpy Balance Temperature Model now has the same calculation options as the Improved Approximation Temperature Model (including Choke Performance calculations) Allow Solution Node at first node for system calculation in Improved Approximation/Enthalpy Balance models. ESP modelling (not Design) available for Improved Approximation and Enthalpy Balance temperature models Target GOR calculator and extended options Improvements in phase behaviour calculation for compositions rich in sour gases (CO2 and H2S) Increase size of PVT Match tables. Add Impurities to Retrograde Condensate Black Oil model. Improved error handling and reporting Calculate the flow velocity across the completion as a function of open perforations, frac pack properties and formation properties. (Casing Velocity (Vc) & Screen Velocity (Vs) calculated in Gravel Pack Section) Add Beta Factor in the gravel pack pressure drop prediction. (Calculated or Entered) (See Gravel Pack) IPR Sensitivity Calculations now available from IPR Section. Pressure dependent permeability IPR Test Points - this section has now been rewritten and enhanced to separate it from the multirate test point input data. Test points are now displayed on all relevant screens/plots It is now possible to change the port size and recalculate output parameters in the GasLift Design Calculation Screen Enable de-rating of Thornhill-Craver flow rates in GasLift Design Real GasLift Valve Response Modelling Add IPR button to GasLift Design screens to enable easy modification of Inflow model during GasLift Design
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PROSPER
Allow Choke Performance calculations in the Prosper Enthalpy Balance Model Addition of a Choke Performance Plot in the Choke Performance section. New lift curve formats are available for CMG reservoir simulators IMEX and GEM. Generate for GAP has been enhanced for Naturally flowing and ESP wells to allow up to ten manifold pressures as input OLGA 2-phase and 3-phase correlations are now available directly from Petroleum Experts. Please contact us for details of cost and installation. Data Entry for Temperature Gradients in Enthalpy Balance model was been rewritten, including the addition of the Geothermal Gradient to the model. Injected Fluid Temperature is now available as a sensitivity variable Heat Transfer Coefficients as sensitivity variables Ability to put in reservoir pressure in VLP/IPR matching screen that corresponds with each test. Add "date" field to well test table so the Match Point Comment column can be used for actual comments. VLP MAtching for ESPs QuickLook from VLP/IPR Matching IPR/VLP plot - include well test date info for test point info entered Make left hand intersection (for gas coning) available. (This is already automatically done if coning flag is set) Preferences Section It is now possible to display the Users Comments on the main screen instead of the Program and Contact details. User preference to allow the user to set the file name and path displayed/hidden. The User can specify default roughness for tubings and pipelines. New OpenServer Generate Rate commands for INF, SYS, SY4, VL3 & VL4 New OpenServer Commands PROSPER.ANL.JET.DESIGN New OpenServer Function to detect Matched PVT (PROSPER.PVT.MATCHED) Open server command that would be equivalent to clicking on the Clear button in the sensitivity variables section. OS command to implement API RP43 Calculation ( calculate perforation length & diameter) Open-server variables and command to enter a MD in the deviation survey section, and calculate its corresponding TVD. OS Command to do Deviation Survey Filtering Reset, transfer and calculate angle OS command for Deviation Survey Filter Implement PROSPER.ANL.SPD.CAL(v1,v2,v3) and PROSPER.ANL.SP4.CALC(v1,v2,v3,v4) Addition of
Sensitivity Summary Export in the 4 Variable System Sensitivity Analysis
Section. Allow the entry of up to 2 Gauge Depths to VLP calculation screen. Pressures are then calculated at these depths and displayed and reported. The calculated pressures are also included in exported TPD files for integration into IFM New variable available "Gas Fraction At Pump Intake" in ESP design calculations screen Remove MacLeod as an option for Horizontal Well Models Warn user if a lift Curve table contains invalid variables for any particular given format. (Warning is at file creation time)
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Technical Overview
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Increase size of PVT Match Tables Add Impurities to Retrograde Condensate Section (Black Oil PVT Model only)
Version 9.0 This note is a summary of the main additions that have been incorporated into the PROSPER program since the 2005 official release. PVT Enhancements · Equation of State The objective of the following improvements is to enhance the compositional modelling capabilities of Prosper: · PVT modelling with EoS available for Injector wells · Enhanced Optimisation · Common EoS options throughout IPM Suite · Path dependent variables (volumetric properties like GOR, FVF, CGR) can be calculated using three different methods leading to standard conditions: · Straight flash to stock tank conditions · Flash through a train of up to 10 separators · Using individual separator stage or full plant K-values · Enhanced plots of generated fluid properties · FVF calculations with Volume Shift validated for mass balance Inflow Enhancements · Modified Isochronal IPR model This IPR model utilises the modified isochronal well test, which consists of repeated shut-in periods of equal duration as the flowing periods. The IPR model is based on the back-pressure equation. · Modelling perforation diameter and length varying rock hardness The API RP43 can be used to calculate the perforations characteristics · Inflow calculation Improvements · Display calculated inflow model PI on the IPR plots · Use of the Perforation Efficiency in all the skin models Determines the number of open perforations. It is applied to shot density in a similar manner to gravel pack calculations · On-screen Help with gravel pack data for given gravel sizes · Enabled appropriate Inflow models for given well configuration · Coning Calculation - the length interval has been decreased · Inflow Calculation - the GOR can be entered and sensitised upon Outflow Enhancements · Gas Condensate Plots Oil as well as Gas can be plotted on the X-axis · Lift Curves Improvements · Export Options saved to file · More data in comments · User configurable data added to file · System Calculation · 4 Variable System Command is available · Export Lift Curves option is available © 1990-2011 Petroleum Experts Limited
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PROSPER
· ·
VLP Matching procedure has been improved Simultaneous injection of Oil and Water
Flow Modelling Enhancements · Pipeline Calculations · Slug Characteristics Surge factors for gas and liquid in the bubble and slug are calculated to describe the slug characteristics of the flow · Pigging Calculations Calculations to determine the pigging characteristics of the flow · Modelling Pressure and temperature drops across fittings dP and dT can be calculated for a very wide variety of fittings by using equivalent lengths. Tabulated L/D values for each fitting type are used to calculate an appropriate K Value for each different type of fitting and configuration Artificial Lift Enhancements · Jet Pumps · Modelling of existing Jet Pump installations · PVT modelling of the Power Fluid · Possibility to store the pump models in the Artificial Lift Database · Exporting lift curves to simulators · Design of new Jet Pump installations · Diluent Injection · Modelling of Diluent injection in the wellbore · PVT modelling of the Injection Fluid · Possibility to sensitise on injection depth and rate · FRAMO Pumps · Modelling of Multiphase pipeline booster pumps Wizards This feature guides the User in setting up models and performing certain tasks following a predefined sequence. A few wizard examples are available when installing PROSPER. These examples are step-by-step guides to build typical models, like naturally flowing wells, ESP, etc. However, the User can create his own wizards to performed given tasks. This option is particularly useful when repetitive calculations are to be performed on well models. The Wizard is based on a VB script. The script consists of a series of VB commands using OpenServer strings to set the values of the input parameters or to call up the appropriate data entry screen , perform calculations, and retrieve or plot results.
OpenServer Enhancements · New Commands · The following capabilities have been implemented: · PVT Match and Match All · 4 Variable System Calculation command · Estimate U Value in VLP /IPR Matching Command · Export of lift curves from VLP and System calculations · HSP design - System Calculation command · Perform Coiled Tubing and Jet Pump Design · Menu commands to open the input, calculation and plot screens PROSPER Manual
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Evaluation Dialog This option can be used to test OpenServer Commands without building VB applications. The basic OS actions (DoSet, DoGet and DoCmd) can also be used to quickly initialise and resetting the data · Open Server Help · Command List · Variable List · Function List ·
Miscellaneous Enhancements · Deviation Survey Filter This feature allow to enter up to 1000 points from deviation survey tables and determines a minimum number of deviation points that best fits them · Calculate Torque for ESP wells The Shaft Torque is calculates during the phase of ESP design
Version 8.0 This note is a summary of the main additions that have been incorporated into the PROSPER program since the 2001 official release. Online PROSPER in GAP · PROSPER flow modelling is now available in GAP. It can be used to model pipelines and wells. It can be used directly as an online calculator or offline to generate lift curves (to speed GAP network calculations) · Lift Curves Data stored in GAP Data stored in external PROSPER file. · PROSPER online Data stored in GAP Can be imported from an existing PROSPER file · Calculation Detail Calculations can be viewed with the precision and detail of PROSPER Gradient screen · Implicit access to all flow and fluid modelling technology in PROSPER Advanced Flow Correlations (e.g... Petroleum Experts, GRE, Hydro 3 Phase) Flow Correlation Matching Choke Modelling Fluid modelling and matching (especially Condensate) Enthalpy Balance calculations for rigorous pressure and temperature modelling. Implicitly includes Joule-Thomson effects Artificial Lift options Gas Lift (Standard and Coiled Tubing) Electrical Submersible Pumps (ESPs) Progressive Cavity Pumps (PCPs) PVT Enhancements Equation Of State Goal for these improvements is complete compatibility to ensure that results obtained in © 1990-2011 Petroleum Experts Limited
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PROSPER
PVTP can be reproduced exactly. · Omega A, Omega B can be entered · Choice of Peng-Robinson or Soave-Redlich-Kwong · Parameter Estimation (Fill In Table) · New Composition Export to PVTP · Improved Composition Import from PVTP (including Reservoir Temperature) · True Critical Point calculation included as part of Phase Envelope Calculation. This helps speed improvements due to quicker phase detection. · Improve calculation speed without compromising results Optimise - None - 2 - 3 times faster } Raw PVT Optimise - Low - 10 - 20 times faster } Calculation Optimise - Medium - 30 - 80 times faster } Speed Improvement PROSPER Example System Sensitivity on 3 tubing sizes Original - 3+ hours None - 95 minutes Low - 12 minutes Medium - 2 minutes 40 seconds · Allow more calculation flexibility for Equation of State models Target GOR User enters initial composition Target GORs are entered as sensitivity variables Program iterates from original composition to a composition with specified GOR New composition saved as a result for display and/or reporting Black Oil ·
·
PVT Lookup Tables Increased size (Number of Temperature Tables (10 -> 50 ) Number of Pressure Entries ( 15 -> 100 ) Generate Option PVT properties for all phases are available in table User responsibility to ensure material balance is preserved Standard Conditions Warning User is notified when there is no entry in the table at standard conditions. Common cause of problems due to interpolation errors. Convergence Pressure Method removed. EoS model improvements (and faster computers) make this redundant
Flow Modelling Enhancements Norsk Hydro Three Phase Correlation (Hydro3P) Solves the steady state momentum equations for three-phase gas/oil/water pipe flow computing pressure drop, water and oil hold-up and oil droplet fraction in the gas. Also models oil-in-water phase and water-in-oil phase. Initial comparisons very favourable. Reasonably fast and very robust. Works for a wide range of conditions for all fluid types. Very fast for two-phase system. Much slower for three-phase systems. Modified Turner Equation For Liquid Loading Used to determine unstable flow regions in Gas or Condensate wells with liquid production. Has been found to be not necessarily reliable. The original Turner Constant was 20.4. It has been found (using Petroleum Experts 4) that 2.04 gives much more reliable results in a wide range of examples. This constant can be changed by the user. Erosional Velocity Calculations With Sand Production PROSPER Manual
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Implementation of a ConocoPhillips paper (An Alternative to API14E Erosional Velocity Limits for Sand Laden Fluids) which challenges API14E (the industry standard) on the basis that it can be very conservative for clean service and is not applicable for conditions where corrosion or sand are present. It proposes a simple alternative approach that has been verified by a comparison with several multi-phase flow loop tests that cover a broad range of liquid-gas ratios and sand concentrations. Step Size This feature allows the user to specify the default step size used in Flow Modelling calculations Artificial Lift Enhancements · Rewrite database One database for all artificial lift types Completely redesigned interface · Booster Pumps ESPs in pipeline. · Implement Progressive Cavity Pumps (PCPs) · HSP & PCP Lift Curves for GAP · Gaslift Allow injection in pipeline (above wellhead) Allow a valve at the design depth of injection (as well as an orifice as at present) Gaslift Adjustments Provides additional calculations for testing gas lift designs under operating conditions. Surface casing pressures when restarting production are presented in addition to input parameters needed for setting up automatic well controllers · Coiled Tubing Gaslift Can already be achieved in PROSPER using annular flow but requires manual set up by user New input options to make problem set-up automatic Description via ID and Thickness makes sensitivity analysis more flexible Enthalpy Balance Model Enhancements · Convection in mud between casings Selectable the the user · Sea Velocity gradients As an addition to the Sea Temperature Gradient · Correlation Comparison Implemented for both Tubing and PipeLine · Extra variables in gradient display Enthalpy (gas, oil, water) Conductivity (gas, oil, water) Specific Heat Capacity (gas, oil, water) · Fix outside casing temperature at time t=0 Diffusivity equation only valid for t > 0.5 days · Casing Conductivity user selectable Previously was a fixed value Inflow Performance Enhancements · Simple MultiLayer Increased number of Layers ( from 5 to 50) · MultiLayer With dP Loss New Layer Models Fractured Well Horizontal Well © 1990-2011 Petroleum Experts Limited
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Increased number of layers (from 20 to 50 layers) Gas and Condensate Implemented Improved IPR DLL Add a skin model to internal reservoir model Proper validation of user data Access to internal model data Ability to deny access to unauthorised users
Non-Newtonian Fluid Modelling · New Model Implement Model based on drilling fluid models developed by Total. This will enable foams in heavy oils to be modelled more accurately. However, it should be noted that this model does not estimate the apparent viscosity of the emulsion with water. Research on another program (REVEAL) is ongoing on this subject. Calculate Equivalent Apparent Viscosity Oil and Gas viscosities both set equal to Apparent Viscosity Implemented in reservoir by calculating an equivalent pipe radius · User DLL User DLL option allows user to test internal models within PROSPER via the usual DLL interface. Will allow the user to model viscosity of all phases (if required) Benefits of testing and implementing engineering technology and research without having to design and maintain the testbed Import DLL · Allows user to import from any file (binary or ascii) if they know the precise format. · Can be used for legacy applications with proprietary format. · Import from a report output of another application · Can be done without any input from Petroleum Experts (avoids confidentiality conflicts) · Integrates seamlessly with File Open option. · User file type just becomes another available file type to read · Can be used in batch mode to convert many files and automatically creates PROSPER input files · Uses OpenServer strings to push the data from user DLL to PROSPER. Choke · · ·
DLL Improvements Allow more user data per DLL Saving and recalling user data to file Redesign Choke Performance screen to allow use with user defined choke DLL
Lift Curves · Additional Formats ChevronTexaco CHEARS ExxonMobil EMPOWER · VIP Format Update Previously if one specified GOR then rates were Oil and if one specified GLR rates where Liquid Now, it is possible to mix and match Gas Fraction Types and Rate Types · General Point Please keep us informed of changes in format - we like to respond as quickly as possible to keep users up-to-date Documentation of lift curve format should be as comprehensive as possible. Quite often, the only documentation is an example file. It can be quite difficult to extrapolate from one PROSPER Manual
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example to a complete solution. The following points are quite useful to note. Specify all possible Gas Fraction Types (GOR, GLR OGR etc) Specify all possible Water Fraction Types (WC, WGR, WOR etc) Rate Types ( Oil, Liquid Gas) Artificial lift types (don't forget pumps) All fluid Types (oil, gas and condensate) Unit types for all variables and unit sets as well (Field, SI, LAB) Producers and Injectors Variable Combinations - what is valid and what is invalid Left Hand Intersection in SYSTEM Calculation Normally VLP/IPR intersections that occur when the tubing pressures are declining (on the LHS) are considered to represent unstable flow and are usually ignored. When Gas Coning occurs however the GOR is changing constantly for different rates and it is possible to have two solutions and for the LHS intersection to represent stable flow Add option to allow user to select which intersection to use Miscellaneous · Units Popup Right-clicking on units field on screen shows user all available units for the variable and its current selection and allows the user to change this current selection. · Extended and Improved Data Validation · MultiLateral - set end points for curve calculations · OpenServer - NEWFILE & SHUTDOWN commands · Export - data formatting improvements · Plot Legend - data content improvements
Version 7.5 This note is a summary of the main additions that have been incorporated into the PROSPER program since the 2000 official release. Make Prosper more accessible to other IPM Tools Much work has been done restructuring PROSPER so that all the single-well technology and engineering can be readily utilised by other programs in the IPM suite.The results of this radical restructuring are not obvious or available at present but will be incorporated in the next versions of GAP and MBAL Model Annulus and Tubing Production A model has been Implemented for production through the tubing and annulus at the same time and also a variable flow path i.e. fluid can flow in either the tubing or the annulus or both and this can vary in different segments of the well Vlp/Ipr Matching Improvements Ability to perform a Correlation Comparison for each test point. Data is automatically transferred from the test point straight to the Correlation Comparison screens. VLP/IPR plot has been enhanced to provide a VLP curve for each test point for a selection of flow correlations. Estimating U values in VLP/IPR matching section from entered Tubing Head Pressures in the Rough Approximation Temperature Model Pipe Matching Improvements Ability to perform a Pipeline Correlation Comparison for each test point. Data is automatically transferred from the test point straight to the Pipeline Correlation Comparison screens. Multi-Lateral - Improvements Model © 1990-2011 Petroleum Experts Limited
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Calculation Dialog Screen Improvements. Multi Layer (Layer-by Layer ) response calculated and plotted. PVT Section Water Vapour Condensation Correlation for Gas Wells Water Viscosity Variation with Pressure Boiling Temperature column in EOS model. Parachor column in EOS model (for Surface Tension Calculations). Editable EOS Component Name instead of number Miscellaneous New variables displayed in Gradient Calculations. Oil Viscosity Water Viscosity Liquid Density Total mass Flow Rate Oil mass Flow Rate Gas Mass Flow Rate Water Mass Flow Rate Oil Formation Volume Factor Gas Formation Volume Factor Water Formation Volume Factor Water Holdup Slip Water Velocity Superficial Water Velocity Cumulative Liquid Volume Cumulative Water Volume Cumulative Oil Volume Cumulative Gas Volume Cumulative Liquid Holdup Cumulative Water Holdup Tubing Flow Rate Annulus Flow Rate New layout options in Gradient Calculations Depth Calculator in Equipment Deviation Survey screen Improved errror checking in IPR section subDialog screens Improvments in annulus configuration management (Enthalpy Balance) Improvements in Drilling section error reporting Improvements to TPD file generation for ESP wells File List - browser for viewing /summarising PROSPER files. Standing correction to Vogel in IPR calculations.
Version 7.0 This note is a summary of the main additions that have been incorporated into the PROSPER program since the 1999 official release. 32-bit Improved memory management. Long File and Directory name. Results Management. Implementaion of Open Server PROSPER Manual
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Open Data/Function Server implemented the same as GAP and MBAL MultiLateral Model has been enhanced and extended Models all fluid types (oil, Gas and Retrograde Condensate) Models Producers and Injectors Can be used in conjuction with artificially lifted wells (Gaslift, ESP and HSP) Enthalpy Balance Temperature Prediction Complete rewrite of enthalpy balance temperature prediction method to allow more flexibility and accuracy. Account for air and sea velocities. Improved Completion fluid handling. Can specify cement and casing conductivity Account for temperature gradient in the sea. Improved Rough Approximation Temperature Model Specify heat transfer coefficient by depth and pipe section Define a temperature gradient for the sea Can make use of Joule-Thomson coefficient Constrained Calculation with Enthalpy Balance Determine pressure and temperature profile for the entire well from the wellhead pressure and bottom hole temperature Thermal Fracturing Model the combined effects of temperature, stress and fluid mechanics to predict the inflow behaviour of injection wells New Correlation (Petroleum Experts 4) Advanced mechanistic model for any angled wells (including dowhill flow) suitable for any fluid (including Retrograde Condensate) Solids Transport Predicting maximum grain size that can be transported. Hydrates Flagging User entered table describing pressure-temperature regions where hydrates formation is likely. The program will then highlight areas with a potential for Hydrates Formation. Miscellaneous User can specify default Units System (on Preferences Screen).
Version 6.0 This note is a summary of the main additions that have been incorporated into the PROSPER program since the 1998 official release. INFLOW New Interface Implemented for all fluids. Completely redesigned to ease user input and to integrate with the external, user-written IPR model enhancement (see below) MultiLateral/MultiLayer Inflow Model Implemented for all fluids. Deviated Well Model Implemented for all fluids. Based on a model produced by Wong and Clifford Dual Porosity Model Implemented for all fluids. Assumptions: For naturally fractured reservoirs where the matrix (formation) porosity is greater than © 1990-2011 Petroleum Experts Limited
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the fracture porosity and the matrix permeability is much smaller than the fracture permeabilty, but not negligible. Source: See References Horizontal Well with Transverse Vertical Fracture(s) Model Implemented for all fluids. Assumptions 1. Circular fractures. 2. Well goes through centre i.e. no shape factor implemented. 3. Fractures are equally spaced - so if there is just one it is in the centre. Source: See References User IPR Model DLL Allows the user to develop their own inflow model(s) and implement it within PROSPER in a similar fashion to flow correlations. The user-developed model can encompass every element of an inflow description including the reservoir model and every component of the skin or can simply be any particular element. Please contact us for details on how to implement this for the specific application Dietz Shape Factor Calculator Implemented for 'Darcy-like' models in all fluids. Assumptions: Calculation is for vertical wells rectangular reservoirs. Source: See References Gas Coning Implemented for oil. Modifies solution GOR by multiplying it by a weighting factor greater than 1, which is a positive function of the liquid rate. The output is a total, or produced, GOR. This model has been implemented with the facility of matching/tuning to real test data Assumptions: High permeability reservoirs. Source: See References. EQUIPMENT More Pipeline nodes Reverse x,y coordinate system for pipeline data entry Rate Multiplier Per Node Option to "disable" Surface Equipment
FLOW MODELLING Complex Terrain Flow Correlation Slug modelling Correlation Threshold Angles Erosional Velocity (C Factor) calculation. Flow Regime Plots More detailed data displayed during Gradient calculations Phase Densities, inter-phase IFTs, slug and bubble properties ARTIFICIAL LIFT Hydraulic Drive Downhole Pumps (or HSPs) Design System Sensitivity and Lift Curve Generation QuickLook diagnostic Pump and Turbine Database management MISCELLANEOUS Preferences All options relating to the customisation of an individual installation of the program have been PROSPER Manual
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gathered together in one location. This option can be found on the File menu and has four sections (tabs)for ease of use. These are Screen File Plot User Applications Welcome Screen This screen is displayed immediately the program is started and is destroyed as soon as the main screen appears. There can be a significant time difference in some cases between these two events and this screen will assure the user that the prgram has indeed started. The reason for the time difference could be any of the following 1) Program Installation - The program could be on a remote network drive and network traffic would affect access time. 2) Software Key - a network installation could slow access to the key is the network is busy. 3) Last file loaded - if one automatically reloads the last file on program startup,then the file size and location(remote network) could make a difference New import format for PVTP file The new format exported from the PVTP program includes more details (Volume Shift flag and the separators included in the analysis.) Screen Design Redesign of many data screens. More consistency between data screens, navigation, and flexibility of screen size (see Preferences-> Screen)
Version 5.1 This note is a summary of the main additions that have been incorporated into the PROSPER program since the 1997 official release. Changes to EOS model The method of calculating GOR and FVF has been enhanced to take account of the fluids path back to surface. Up to 5 separator stages can be defined. The fluid is flashed through any defined stages to find the resultant gas/oil mixture in the accumulator/stock tank. If no stages are defined a single flash to ambient conditions is performed. WHP to BHP Method for calculating flowing bottom hole pressure from the wellhead pressure for a large number of points. VLP Matching Ability to allow or disallow the plotting of labels. Added ability to export and report from this screen. Output more information to reports Miscellaneous The following bug fixes/ improvements. Errors in files when saving long labels from downhole/surface equipment. Sensible choice for file prefix when saving files. Improved error checking in relative permeability screen in IPR section. Scaling problems on status screen IPR plot when changing units have been fixed. General updates to Status Screen Errors transferring surface equipment details when changing from Pressure only to Pressure and temperature prediction have been corrected. Improved legend for Gaslift Design Plot © 1990-2011 Petroleum Experts Limited
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Improved legends for plots generally for consistency. Improved handling of multi rate input data in IPR section. Load correlation DLLs automatically from run directory. Fixed errors in PVT matching reports Fixed errors for water injectors reporting marginal amount of oil Improved depth error checking in equipment section Fixed bug in gradient calculation section (not setting Top Node Pressure and Rate correctly) Insert a check for Choke Model selected when reading files. Fixed EOS calculation initialisation problems. Added feature to output 4 variable MBV (lift curve ) files ESPs - allow user to select location of database files Sensitivity analysis - improved error checking in variable selection Status screen error for PVT Condensate display (wrong unit for CGR/WGR) System Plot - wrong label for Gas Rate has been corrected. IPR - improved calculation of combined Total GOR for multi layer IPRs Gray Correlation - advise of unsuitability for use in Pressure and Temperature predictions PVT Matching - ability to transfer data from Tables and import data from PVT Program PVT Tables - ability to import data from Matching Section.
Version 5.0 This note is a summary of the main additions that have been incorporated into the PROSPER program since the 1996 official release. Report Generator The reporting interface gives complete control over how the reports are formatted and what information is utilised to make up the report. This is facilitated by the use of report templates which can be edited to suit the users's own requirements. One can choose to use the default report templates provided with the system or can choose to create its own slightly different versions of these reports. The selected templates can then be used to generate the actual reports which can be sent to a variety of places (printer, file or screen). Flexible Importing This facility is designed to let the user import tabular data from a wide variety of files and databases via ODBC. A filter 'template' is configured visually and can be saved to disk for future use. It can also be distributed easily to other users. User Choke Model DLL Allows the user to develop their own choke model and implement it within PROSPER in a similar fashion to flow correlations New Choke Model (from ELF) A model based on Perkin's (SPE 206333) approach along with discharge coefficients determined by the author (Stephane Rastoin of ELF Aquitaine at TUALP) Pipe Correlation Comparison A technique for comparing pipeline flow correlations against observed data similar to the existing Correlation Comparison for tubing correlations QuickLook for ESP PROSPER Manual
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A diagnostic technique for analysing ESP lifted systems to determine if the pump is performing as expected and to trouble shoot for potential problems Inipath A option to allow users to run PROSPER from one network copy whilst maintaining their own configurations in private copies of PROSPER.INI New Gaslift Design Options New Emulsion Viscosity Modelling Options Generate TPD files for GAP Extended lift curve format to allow modelling of ESP systems in GAP Expanded EOS Import Format Allows user to import all the data that is normally generated by Petroleum Experts EOS model. The file format is flexible to allow for multiple compositions and the results obtained for each composition. This allows the possibility in the future to generate sensitivities for several compositions. (e.g. EOSbased lift curves) Gradient Test Data Allows output of consistent test data on all gradient plots in PROSPER ESP Database Handling Improved Database information regarding current pump, motor and cable in use is stored on file to enable distribution of files easily between users Water Injector As Specific Well Type Allows easy setup an minimal PVT data entry to handle this well type. Variable Solution Node Allow solution node at sandface, wellhead or manifold Injection Model For Temperature Improved (Rough Approximation Model) Improved Equipment Data Entry Many problems for users are caused by incorrect entry of equipment data. Improving error detection in this area helps to reduce support requirements and improves usability of the program Pipeline Calculation Only Simplify setup (especially for equipment) in order to model pipeline flow New Tubing Correlation (Petroleum Experts 3) Plot Annotations
Version 4.5 This note is a summary of the main additions that have been incorporated in © 1990-2011 Petroleum Experts Limited
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PROSPER since the May 1995 release. Black Oil PVT Added new Pressure-Volume-Temperature Correlations for Gulf of Mexico Crude Oils due to Petrosky et al (SPE26644) Added new Viscosity Correlations for Gulf of Mexico Crude Oils due to Petrosky et al ( SPE29268) Allow modelling of emulsion viscosity corrections for OIL-WATER mixtures. Improved matching for heavy oils.
Equation of State PVT from external DLL Added a new interface to give user's the ability to program their own equation of state PVT model and link it to PROSPER. FLASH.DLL routines updated to closely follow PVT Package calculations. This has resulted in improved viscosity, liquid densities and phase detection. Stability has improved for low molecular weight liquids and gas.
ESP's Emulsion PVT applied to ESP head, power (and consequently) efficiency corrections. Intake gas fraction sensitivity plot (Dunbar plot). Tubing automatically terminated at pump depth. Database report improved.
Inflow Performance Multi-layer - Upgraded for injection wells. GAP and MBAL links. IPR points are transferred directly to GAP or saved in a file for MBAL. SkinAide - new IPR model from ELF
Gaslift Design Optional checks for rate conformance with IPR during design. Expanded design options and additional logic for valve closing pressures. Improved dome pressure temperature correction above 1200 psi. Design plot shows unloading fluid gradients, actual surface injection pressure and production rates. Database report improved.
File handling Significant reduction in all file sizes due to implementation of file compression techniques. Improved error handling in low space (disk nearly full) situations. Speed up file reading/writing..
Error Checking
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Improved the checking of equipment entry
Units Revised to include validation option on main Units screen. New options added to allow user selection of precision of display,
Reports Screen reporting more flexible Font handling problems (with regards to font size) fixed. Printer fonts are now entered as point sizes instead of relative size units. This avoids the need to adjust printer font sizes when changing printers Batch Automatic Batch generation of tubing curves(VLP) and inflow curves(IPR) via improved interface with GAP
ProdMan ( Production Manager) Provision of visual field modelling with automatic access to PROSPER and capability for batch mode operation for certain calculations. (GAP without the modelling and optimisation features)
Calculation / Generate for GAP Rate logic improved for high rate producers and injectors.
Calculation / System User selection of sensitivity values on plots.
Calculation / Gradient Plots can now be made for the entire system including both well and pipeline. Extended range of plot variables available. Miscellaneous Plot results in multirate IPR's. Reset buttons in sensitivity variable selection screen Screen appearance has been improved to improve layout and readability. IPR MultiLayer report Separate units available for Anisotropy, PumpWearFactor, TimeToSurface and Volume Allow selection of curves to plot in VLP Store and report Depth Of Injection in gradient sensitivty analysis Fluid Flow Correlation Parameters report added Last file loading option Previous files loading option.
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Version 4.0 This note is a summary of the main additions that have been incorporated in PROSPER since the May 1994 release. General UNIX versions have been shipped for HP 9000 and IBM RISC. Other platforms can be supported on request. New program installation procedure build program icon and group automatically. Stackable keys now supported.
Black Oil PVT Black oil PVT now handles 100% CO2. (Accuracy verified against measured data) Composition estimation from Black Oil properties. Estimated composition now used for calculation of thermodynamic properties (enthalpy, entropy) for choke calculations etc. This improves the accuracy of the Enthalpy Balance temperature predictions for high GOR cases. Black oil PVT lookup table file import available.
EOS PVT EOS PVT input screen editing improved. Now allows input of up to 30 pseudocomponents. Critical volume is now passed between PVTP and PROSPER. This improves PROSPER viscosity calculations for some fluids. For old files, Vcrit is estimated using a correlation as before. EOS algorithms improved and run faster. EOS oil density now used instead of Standing and Katz.
System I Equipment Sketches of both surface and downhole equipment can be drawn from the summary screen. Surface equipment geometry can be optionally entered as TVD, Length or X,Y co-ordinates.
Inflow Performance Relative permeability can be optionally used in oil IPR calculations. PROSPER allows entry relative permeability curves and the water cut at a test rate. PROSPER now calculates IPR sensitivities for water cut. Fractured well IPR improved for both short and long flowing times. Horizontal well - friction dP. This major development allows modelling of horizontal well accounting for friction loss, gravel packs for oil, gas and condensate. Multi-layer - Layer dP. A network algorithm is used to solve multi layer IPR while accounting for pressure differences between layers. Available for oil now, gas and condensate in Summer 95.
Matching IPR matching facility added. Allows IPR to be compared to matched test pressures. This is PROSPER Manual
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a useful graphical means to find reservoir pressures and to examine changes in well condition and quality control the well model. Match data screen re-worked to allow cut and paste to/from windows clipboard. Match data comment field added.
Calculation / Inflow A new Inflow section has been added. This enables sensitivities for IPR variables to be quickly calculated without the need to calculate the VLP also (System calculation). The range of sensitivity variables has been expanded with completion design in mind. User selected rates can be now be Generated if required. This is useful for IPR sensitvities when Automatic rates are determined by the AOF for the base case. Sensitivity variables values can be Generated also.
Calculation / System The range of outputs displayed expanded to include wellhead temperature, pressure loss components, gas injection depth.
Calculation / Gradient Plots can now be made for the entire system including both well and pipeline. Extended range of plot variables available. Range of sensitivity variables expanded.
Calculation / VLP Lift curve variables are sorted and filtered so that only valid sensitivity variable are considered. Number of VLP table entries increased from 1296 to 10,000 Increased range of VLP variables and simulator formats supported. (COMP3 VIP & MORE) For oil wells, VLP can be calculated in terms of gas rates VLP algorithms improved for very high GOR. Additional VLP correlations - Petroleum Experts 2 (improved loading rate calculations) and Duns and Ros Original.
Calculation / Choke General purpose choke tool can find: flow rate, pressure drop or choke size. Calculation based on thermodynamic principles, not empirical correlations.
Calculation / Generate for GAP Now active even if PROSPER has not been called from GAP. This allows an engineer to work with PROSPER independently of GAP. For naturally flowing wells, 5 generate pressures can be input and calculated. Generates performance curves for both injection and flowing wells.
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Design / Gaslift design Design logic has been improved and greater flexibility in design methods is provided. Fixed mandrel depth design selects the best location for unloading valves from a list of preset mandrel depths.
Design / ESP design Current (1992) motor characteristics for REDA motors included in database. ESP Inc. motor and pump data included in database
1.7
Examples Guide This chapter contains a collection of tutorials designed to help jump-start the use of PROSPER. The tutorials are grouped by subjects: Integrated well bore models · Basic Tutorials for naturally flowing wells, · Sand control tutorials · Compositional modelling tutorials · Well test matching tutorials · Artificial lift design tutorials · Tutorials about trouble-shooting artificially lifted wells · Tutorials on pipeline modeling and flow assurance studies. · Tutorials on special topics Integrated well bore models Tutorial 00
Description Integrated oil well model
Reference File T00_IntegratedOilWell.OUT
Basic tutorials for naturally flowing wells Tutorial 01 02 03 04 05 07 08 09 10 11
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Description Reference File Modelling a dry and wet gas producer T01_DryAndWetGasWell.Out T02_SimpleOilWell.OUT Modelling a naturally flowing oil well Modelling an oil well with black oil PVTT03_OilWellPVTMatching.OUT matching T04_HorizontalOilWell.out Modelling an horizontal oil well Modelling a multilateral dry gas producer T05_MultilateralGasWell.Out T07_SlantedOilWell.Out Modelling a slanted oil well Modelling a gas well with connected T08_GasWellwithSurfacePipeline. Out pipeline T09_WaterInjectionWell.OUT Modelling a water injection well T10_GasInjectionWell.OUT Modelling a gas injection well T11_SteamInjectionWell.OUT Modelling a steam injection well
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Sand Control tutorials Tutorial 12 13 14 15 16
Description Modelling an oil well with gravel-pack Modelling a frac and pack well Modelling a well with pre-packed screen
Reference File
T12_GravelPackedOilWell.OUT T13_Frac&PackedOilWell.OUT T14_OilWellwithPrePackedScreen.out T15_OilWellwithslottedLiner.OUT Modelling a well with slotted liners Modelling a well with wire-wrapped T16_OilWellwithWireWrappedScre ens.out screens
Compositional modelling tutorials Tutorial 17 18
Description Reference File Fully compositional retrograde T17_CompostionalCondensateWell. Out condensate well T18_CompostionalCO2Injector.Out Fully compositional CO2 injection well
Well test matching tutorials Tutorial 19 20 21
Description Matching a gas well test Matching a naturally flowing oil well test Matching a water injection well test
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Matching a gas injection well test
Reference File T19_MatchingAGasWellTest.OUT T20_MatchingAnOilWellTest.OUT T21_MatchingAWaterInjectionWellT est.OUT T22_MatchingAGasInjectionWellTes t.OUT
Artificial lift design tutorials Tutorial 23 24 25 26 27 28 29
Description Continuous Gas lift design Intermittent Gas Lift Design
Reference File
T23_ContinuousGasLiftDesign.OUT T24_IntermittentGasLiftDesign. OUT T25_CoiledTubingGasLiftDesign. Coiled Tubing Gas lift Design OUT Design of an ESP system for an oilT26_ESPDesign.OUT
producer Design of an HSP system for an oilT27_HSPDesign.OUT producer Design of a Sucker Rod Pump for an oilT28_SuckerRodPumpDesign.OUT producer Design of a PCP lift system for an oilT29_PCPDesign.OUT producer © 1990-2011 Petroleum Experts Limited
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30 31 43
T30_DiluentInjection.OUT Diluent Injection tutorial Multiphase pump in a pipe connected to a T31_MultiphasePumpOnseabed. OUT single well Design of a Jet Pump system for an oilT43_JETPUMP.OUT producer
Tutorials about trouble-shooting artificially lifted wells Tutorial 32 33 34 35
Description Troubleshooting a gas lifted well Trouble-shooting an ESP-lifted well Trouble-shooting an HSP-lifted well Trouble-shooting a sucker rod lifted well
Reference File T32_GasLiftQuickLook.OUT T33_ESPQuicklook.OUT T34_HSPQuicklook.OUT No reference file
Pipeline and flow assurance study tutorials Tutorial 36 37 38 39
Description General flow assurance features Pipeline performance matching Full enthalpy balance example Improved approximation tutorial
Reference File T36_FlowAssurance.OUT T37_PipelineMatching.OUT T38_EnthalpyBalance.OUT T39_ImprovedApproximation.OUT
Special topics Tutorial 40 41 42
Description Reference File T40_SPOT.OUT SPOT example Multi-layer model with dP loss between the T41_MultilayerOil.Out zones Multilateral IPR for well penetrating T42_MultiLateralInMultipleReservo different zones irs.OUT
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Validation of the black oil PVT model for T44_CONDVALID.OUT gas retrograde condensate producer
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User Guide This user guide is subdivided in the following sections: · Introduction · File management · Data input - General · PVT data input · Equipment data input · IPR Data Input · Artificial Lift Data Input · Matching menu · Calculation Menu · Design menu · Output · Units · Wizard and · Help
2.1
Introduction Welcome to PROSPER, Petroleum Experts Limited's advanced PROduction and S ystems PERformance analysis software. PROSPER can assist the production or reservoir engineer to predict tubing and pipeline hydraulics and temperatures with accuracy and speed. PROSPER's powerful sensitivity calculation features enable existing designs to be optimised and the effects of future changes in system parameters to be assessed. By separately modelling each component of the producing well system, then allowing the User to verify each model subsystem by performance matching, PROSPER ensures that the calculations are as accurate as possible. Once a system model has been tuned to real field data, PROSPER can be confidently used to model the well in different scenarios and to make forward predictions of reservoir pressure based on surface production data.
2.1.1 Using PROSPER These are the main features available in PROSPER: 1. PROSPER is a fundamental element in the Integrated Production Model (IPM) as defined by Petroleum Experts, linking to GAP, the production network optimisation program for gathering system modelling and MBAL, the reservoir engineering and modelling tool, for making fully integrated total system modelling and production forecasting.
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2. The PVT section in PROSPER can compute fluid properties using standard black oil correlations. The black oil correlations can be modified to better fit measured lab data. PROSPER allows detailed PVT data in the form of tables to be imported for use in the calculations. A third option is to use the Equation of State method. This option also allows the User to enter the equation of state model parameters and uses the standard Peng-Robinson EOS model to generate properties given a multi-stage separator scheme. With this option the Users can also import all PVT data in the form of tables, which could have been generated using their own proprietary EOS models. 3. The tool can be used to model reservoir inflow performance (IPR) for single layer, multi-layered, or multilateral wells with complex and highly deviated completions, optimising all aspects of a completion design including perforation details and gravel packing. 4. It can be used to accurately predict both pressure and temperature profiles in producing wells, injection wells, across chokes and along risers and flow lines. 5. The sensitivity calculations capabilities allow the engineer to model and easily optimise tubing configuration, choke and surface flow line performance. 6. It can be used to design, optimise and troubleshoot the following artificial lift systems: gas lifted, coiled tubing, ESP, PCP, HSP (hydraulic pump), Jet pump and Sucker Rod pump equipped wells. 7. Its choke calculator can be used to predict flow rates given the choke size, or the choke size for a specified production rate and of course, the pressure drop across a known choke at a specified rate. It can also be used to generate choke performance curves. 8. The multiphase flow correlations implemented can be adjusted to match measured field data to generate vertical lift performance curves (VLP) for use in simulators and network models. 9. The tool can utilise externally programmed dynamic link libraries (DLL) for multiphase flow correlations, Equation of State (EOS) PVT calculations, choke calculations, Inflow (IPR) models, HSP Gas De-Rating models and proprietary viscosity models (both Newtonian and Non-Newtonian) . 10. The tool can be used in a matching or predictive mode. Matching of real data is available in the PVT, IPR, Gradient matching and VLP matching sections. · ·
In matching mode, real data can be entered and matched using non-linear regression methods to create custom correlations that fit the input data. In predictive mode, the correlations created can be used to make estimates of future well performance.
11. PROSPER can be used to model complex (topographically) and extensive (in © 1990-2011 Petroleum Experts Limited
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length) surface pipelines. Complex steady state slug analysis can also be performed by taking into account slug build up and decay due to pipeline topography, giving an indication of expected slug length and frequency. Pigging calculations are also available 12. Black Oil PVT tables can be imported directly into PROSPER. The black oil tables can be generated by Petroleum Experts’ PVTP thermodynamics analysis program or from from any third-party application, provided it has the right format (*.PTB file). Equally compositional model can also be directly imported as *. PRP file. 13. A flexible and fully customisable units system is implemented in PROSPER. Data may be input using one set of units and output using a second set of units. Validation limits and display resolution can be independently set for each variable type. 14. It has the utility for flagging of potential hydrate formation, if the User chooses this in the options. The additional input required for this calculation is the hydration formation tables as a part of the black oil PVT description. The hydrate and wax models are readily available if the fluid model in PROSPER is compositional. Note that one can also use Petroleum Experts’ PVTP thermodynamics analysis program to predict waxes and hydrates appearance conditions. A compositional PROSPER model or PVTP can be used to generate hydrate formation tables. 15. The following situations can be modelled: Fluid Type: · Oil and Water (Black oil or Equation of State PVT) · Dry and Wet Gas (Black oil or Equation of State PVT) · Retrograde Condensate (Black Oil or Equation of State PVT) · Emulsion viscosity can be optionally applied for any combination of inflow, tubing and ESP’s or HSP’s. · Separation mode: Single or Two Stage separation or Multistage (for Compositional model) · Modelling of non-Newtonian fluids for oil wells · Modelling of Condensed Water Vapour for gas wells Well Flow Configuration: · Tubing or Annular flow or Tubing + Annular flow · Producer or Injector Artificial Lift Method: · Naturally flowing well · Gas lifted well (continuous and intermittent) · Electric submersible pump (ESP) · Hydraulic drive downhole pump (HSP) PROSPER Manual
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Progressive Cavity Pumps Jet Pumps Gas Lift with Coiled Tubing Injection of Diluents Multiphase Pumps Sucker Rod Pumps
Prediction Type: · Pressure Only · Pressure and Temperature Offshore · Pressure and Temperature on Land Temperature Model: · Enthalpy Balance with or without steam · Rough Approximation · Improved Approximation with or without steam Completion: · Cased Hole · Open Hole Sand control: · Gravel Pack · Pre-packed screen · Wire wrapped screen · Slotted liner · Sand failure Reservoir: · Single Well · Multi-lateral Well in a Multi-layered Reservoir · Gas Coning (Rate dependent GOR calculator)
2.1.2 PROSPER and Systems Analysis PROSPER can help E&P companies to maximise their production earnings by providing the engineering means to critically analyse the performance of individual producing or injecting well. Each well system component that contributes to overall performance is separately modelled: Fluid Properties, Inflow performance, pressure drop in the tubing and pressure losses in the surface gathering system are individually evaluated, analysed, validated and calibrated against recorded performance data whenever possible. Well potential and producing pressure losses are both dependent on fluid (PVT) properties. The accuracy of systems analysis calculations is therefore dependent on © 1990-2011 Petroleum Experts Limited
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the accuracy of the fluid properties model (i.e. PVT). The pressure drop in a pipeline or wellbore is the summation of 3 components: · Gravity head · Friction loss · Acceleration i.e.
Dptotal = Dpgravity + Dp friction + Dpacceleration
The gravity component is due to the density of the fluid mixture at each point in the system and is a complex function of the relative velocity of the phases present. PROSPER makes a flash computation at each calculation step to determine the proportion of oil, water and gas present. The no-slip density is then calculated using the proportions of each phase and the predicted density at each pressure and temperature step. Industry standard 2-phase correlations are then applied to determine the increase in apparent fluid density due to the higher vertical velocity of gas compared to oil and water (slippage). The gravity head loss is proportional to the fluid density corrected for slip. The slip correction to be applied depends on the flow regime, fluid velocity etc. The need for an accurate PVT description for predicting the gravity head loss become obvious. Friction losses are controlled by fluid viscosity and geometric factors (pipe diameter and roughness). In the majority of oilfield applications, (i.e. large elevation difference between inlet and outlet with liquids present) the gravitational component normally accounts for around 90% of the overall head loss. Therefore, the total pressure drop function may often not be particularly sensitive to the value of the friction loss coefficient. The acceleration component is usually small except in systems involving significant fluid expansion. However, it is accounted for in all PROSPER calculations. Historically, systems analysis software has lumped all flowing pressure loss terms together and allowed the User to match real data by adjusting the roughness coefficient of the friction loss term. This will certainly achieve a match for a particular rate, but cannot be expected to achieve a match over a significant range of rates due to the different dependencies of the gravity and friction loss terms on liquid velocity. The recommended engineering approach when modelling wells and / or pipelines response with PROSPER is to first construct a robust PVT model for the fluid. The process consists when possible in entering laboratory PVT data and adjusting the black oil correlation model to fit the measured data while respecting the fluid thermodynamics. This approach consistently improve the accuracy of forward prediction. In essence, an accurate PVT model confines any uncertainty in the gravity loss term to the slip correction only. In the VLP matching phase, PROSPER divides the total pressure loss into friction and PROSPER Manual
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gravity components and uses a non-linear regression technique to separately optimise the value of each component. Not only does the matching process result in a more accurate model, it will quickly highlight inconsistencies in either the PVT or equipment description. Provided sufficiently accurate field data is available, robust PVT, IPR and VLP models can be achieved by validating and calibrating the models against actual performance. Each model component is separately validated, therefore dependency on other components of the well model is eliminated. Understanding potential deterioration in well performance is simplified with such a consistent process that ultimately help reduce the number of unknowns.
2.1.2.1 About PROSPER PROSPER can predict either Pressure Only or Pressure and Temperature. The Pressure Only option makes PROSPER a "Systems Analysis" package in the traditional sense. In Pressure Only mode, the well temperature profile must be inputted by the User. Temperature data is normally recorded whenever a pressure survey is made, as the temperature is required to correct the downhole pressure readings. This type of calculation is fast and sufficiently accurate for the majority of pressure loss calculation purposes. The Pressure and Temperature calculation option will generate both temperature and pressure profiles. Three temperature models are provided. The Rough Approximation model utilises a User-input overall heat transfer coefficient. It determines the steady state temperature profile from the mass flow rates of oil, water and gas before commencing the pressure loss calculations. This method runs quickly, but unless calibrated using measured temperature data, it is not accurate. The Enthalpy Balance model calculates the heat transfer coefficients at each calculation step by considering heat flow and enthalpy changes. The Joule Thompson effect, convection and radiation are modelled. These calculations require considerably more input data than for pressure only calculations and must commence from a known temperature and pressure (the sand face for producers, or wellhead for injectors). Computation times are longer than for the Rough Approximation option, but this method is predictive and gives accurate results over a wide range of conditions. The Enthalpy Balance model is completely transient and can be used to study temperature changes over time. Temperature prediction is useful for generating temperature profiles in: · · · ·
long pipelines transporting Retrograde Condensate. subsea wells with long flowlines high pressure/temperature exploration wells predicting temperature/pressure profiles for flow assurance studies: prediction of wax/hydrate deposits
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The production riser is properly accounted for by PROSPER. The User-input riser geometry determines the heat loss coefficients calculated by the program between the seabed and wellhead. The Improved Approximation is a full Enthalpy Balance model, with the difference that the heat exchange coefficient is not calculated but defined by the User along the completion. Like the Enthalpy Balance model, the Joule Thompson effect is accounted for. PROSPER is also able to predict condensate liquid drop out using either black oil or compositional models. PROSPER uses a "Smart Menu" system. Only data relevant to a particular problem need to be entered. The flow chart below gives an outline of the calculation steps required to carry out a simple systems analysis using PROSPER.
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2.1.3 Examples To help illustrate the power of PROSPER, examples are provided with the program. We suggest to run through them to become familiar with the program and its various options. The example guide provide the User with tutorials covering various dexterity and © 1990-2011 Petroleum Experts Limited
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engineering topics showing how to build, match and use a well model. All the example files related are in the folder ~\samples\PROSPER , where Petroleum Experts software in installed. The location of this directory depends on where the program has been installed. Examples Guide
2.2
File Management This section describes the menus, options and procedures used in PROSPER to create new files and open or save existing files. The Units system and how to define printer settings are also outlined. The menus described in this section are the PROSPER File menu and Units menu. The File menu provides additional options such as defining the default data directory, as well as the facility to establish links to other programs running under Windows. PROSPER will (optionally) open the last file accessed when it starts. PROSPER also displays a file status screen that shows the application options selected in summary format: input PVT and IPR data, the equipment type summary and the analysis output. To protect the work, good practice is to save the file on a regular basis. This simple procedure could potentially prevent hours of input and analysis being lost.
2.2.1 PROSPER Files PROSPER uses a flexible file structure that enables data to be easily exchanged between files and other application programs. In PROSPER information is grouped into the following categories: PVT Data Analysis Data
System Input Data Output Data
and saved into the following types of data file:
2.2.1.1 PVT Data (*.PVT) File containing the well fluid data, PVT match data and any PVT tables entered under the PVT menu. It is possible to save PVT files separately under different names, and use them with other input, analysis and output files in PROSPER. This feature is useful when analysing a number of wells from the same producing pool. The .PVT file can be also imported/exported in/from MBAL models.
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2.2.1.2 Input Data (*.SIN) The *.SIN file contain all the options selected under the Options menu, in addition to the well IPR and equipment data entered under the System menu. When an input file is opened or saved, the program automatically opens and saves a .PVT file with the same name. 2.2.1.3 Analysis Data (*.ANL) This *.ANL file contains all the information from the *.SIN file aloind with all the sensitivity input data for the calculations selected under the Analysis menu. When an analysis file is opened and saved, the program automatically opens and saves a .PVT & .SIN file with the same name. GAP manipulates .ANL files to batch calculate well lift curves. 2.2.1.4 Output Data (*.OUT) This file contains all the inputs and all the results of the calculations. When an output file is saved, then program automatically saves a .PVT, .SIN & .ANL file of the same name. The *.OUT file can be seen as the master PROSPER file. PROSPER files are ranked by their order of input, which essentially reflects the way data should be entered into the program, that is from the LEFT to the RIGHT of the PROSPER menu. It is possible to note that the order of files also corresponds to the options on the menu bar as one is navigating through the program. The file hierarchy does not prevent the User from creating and combining any number of input and output data files. Until the User becomes familiar with the program, we recommend to work with *.OUT files. This can avoid confusion as the program will automatically open and save the required data files to run a complete analysis cycle. More experienced users can take advantage of the flexible file structure to combine the data files from different wells. This "sharing" of data is useful in areas where wells have similar fluid properties or reservoir IPR's. If disk space is a concern, the data contained in a .ANL file together with its complementary .PVT and .SIN files can be used to recreate a given set of calculation outputs, therefore avoiding the need to always save large .OUT files on disk. For example, if one wants to run an analysis with the PVT data of Well 1, the input data (*.SIN) data of Well 2, and the analysis data of Well 3, the following steps can be followed to achieve that: ·
Open Well 2.SIN
·
Recall Well 1.PVT under the PVT menu.
·
Under the Options menu, select the processing options.
·
Modify the data files if necessary.
·
Next, select the Save As command and save the data under a new file name.
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2.2.1.5 Creating a New File While working with PROSPER, new input or output data files can be created at any time. To create a new file, from the File menu simply choose the New command. This command does not actually create a new and separate file, but re-initialises the program input/output data. 2.2.1.6 Opening an Existing File Existing data files can be opened quickly and easily at any time during the current working session. To open a file, from the File menu choose the Open option. It is possible to select one of the following file types: · Input Data (. SIN) · Input and Analysis Data (. ANL) · Input, Analysis and Output Data (. OUT) by using the “Files of Type” dropdown box. The file open dialog is exactly the same as in any Windows program.
2.2.1.7 Saving a File When files are opened in PROSPER, the program copies the selected file into the computer's memory. Any changes to the file are made to the copy in memory. In the event of a power failure or computer crash, these changes would be completely lost. To prevent this, we recommend to save the data on a regular basis and especially before quitting the program. The Save command stores all the changes made in the active file. By default, the Save command saves a file under its original name and to the drive and directory last selected. A prompt will be displayed to select one of the following file types: Input Data (.SIN) · Automatically saves the input file and corresponding .PVT file. Input and Analysis Data (.ANL) · Automatically saves the analysis data and corresponding .SIN & .PVT data files. Input, Analysis and Output Data (.OUT) · Automatically saves the output results and corresponding .SIN, .PVT & .ANL files if a file of the same name exists in the selected directory, the file is overwritten. To avoid overwriting an existing file, use the Save As command and enter a different file name. PROSPER Manual
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2.2.1.8 Copying a File The Save As command allows to make more than one copy or version of an existing file. This command is the same as in any other program running under Windows and allows to save the PROSPER model in any of the file formats (.SIN, .ANL, .OUT).
2.2.2 Preferences The Preferences screen is used to customise the program to the particular requirements. Click Preferences from the File menu to customise PROSPER. Click on the appropriate tab at the top of the data entry section in order to change the option require. The various tabs are described below: 2.2.2.1 Main Screen
This tab is used to customise the appearance of the PROSPER main screen and all data entry (dialog) screens.
Dialog Font
This changes the font type and size used to display all data entry screens. This may be useful to make all dialogs smaller in case of a low-resolution screen or larger to improve readability in case of a highresolution screen. Use the Reset button to reset the dialog screen font © 1990-2011 Petroleum Experts Limited
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to its default value. Status Screen
Selecting On the screen status information will be continuously displayed and updated during the program usage. Selecting Off the screen status information screen will not be displayed (apart from whenever a new file is opened).
Font Height
If the font height is modified then an attempt is made to scale the font so that all information displayed in each panel on the status screen will be visible. This will vary depending on the relative size of the program window to the total screen. If the font height is not modified then some information may not be displayed as the size of the program window is varied.
Screen Font Use this option to change the font type and size used to display information on the status (front) screen of the program. Label Colour Change the colour used to display labels on the status screen Text Colour
Change the colour used to display text on the status screen
Background Change the colour used for the background of the status screen Box Colour
Change the colour used for the background of each panel on the status screen
Box Shadow Change the colour used for the 3D shadow effect on the status screen panels Box Highlight
Change the colour used for the 3D-highlight effect on the status screen panels
FileName Option
Options to display the file name in the main program toolbar. It is possible to visualise the file name with/without the complete path, or a certain number of characters ot not visualise it at all. The changes will have effect as soon as a file is loaded
Length of FileName
Active only if the FileName Option Compact Path/File to Specified Length is selected
Analysis Summary Columns
This option changes the way the Analysis Summary is displayed in the PROSPER main screen
For all of the above “Colour” options the Choose button to the right will bring up a dialog screen to select an appropriate colour.
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2.2.2.2 File
Use this tab to customise various options relating to file management. Default Data The directory where data files are normally stored. Use the Browse Directory buttons to browse for the appropriate directories. Default Data This option determines the directory that is used as the default in file Directory dialog. The choices are either to always use the default data directory (see above) or to use the directory of the last file opened or saved. Choice Reload Last Specifies whether the last file that the User was working with should be File On Start automatically reloaded on program start up. Up Number of File Names Saved
Specifies the number of previously used files that are to be displayed on the file menu.
Location of Import Files
Use this option to specify the default location of the Import files
Import File Directory Choice
Use this option to define the directory that will be pointed every time the file Import function is selected
Location of Use this option to specify the default location of the Import Filter Import Filters Location of Report Output Files
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Location of UserCreated Report Files
Use this option to specify the default location of user-created report templates from the reporting subsystem
Confirm Switches (on or off) the message that appears at the end of any Calculations calculation function. Switches (on or off) file compression for PROSPER files (OUT, ANL, File Compressio SIN, PVT). Default is off. File reading and writing is slower with compression on, but less disk space is used by the file. The user n needs to decide the trade-off between speed and disk space. File Overwrite
This option switches on/off a confirmation message whenever saving and overwriting an existing file
2.2.2.3 Plot
Use this tab to set defaults for all aspects of the plot. Always Use Each time a plot is done default values will be used rather than the last Plot Defaults selected values for each particular plot type X Grid Number of gaps between grid lines on X-axis. (Range 1-20) Blocks
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Y Grid Number of gaps between grid lines on Y-axis. (Range 1-20) Blocks Plot Labels
Shows or hides the plot labels.
Plot Scales
Shows or hides the plot scales
Plot Legend
Shows or hides the plot legend. If the legend is hidden, the body of the plot will expand to fill the whole window.
Scaling Method
Endpoint or rounded. Endpoint means the scales are taken from the exact extremities of the data being plotted. Rounded means that ranges are chosen to surround the data but with whole numbers ensured for the end points and the gridline intervals.
Grid Type
Line
Selects from dotted lines, dashed lines, solid lines or tick marks.
Mouse Readout
Switches the mouse cursor position readout no or off.
Date Title
Selects to append the current data and time to the plot title or not
Stamp
Line Thickness
To select the thickness of plotted lines
Vertical Font Selects the default font for all vertical text (Y-axis) Horizontal Font
Selects the default font for all horizontal text
Default Colours
Sets the default colour scheme for the plot
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2.2.2.4 User Applications
This tab allows to add up to four of the User’s favourite or most-often used Windows applications to the PROSPER menu. Although PROSPER has a very flexible reporting system the User may wish to use a spreadsheet (such as EXCEL), a word processor (such as WORD) and a presentation package (such as Power Point) to build presentation quality reports using PROSPER output in a slick and efficient manner. Any output (plots and reports) produced by PROSPER is automatically copied to the Clipboard. From there it can easily be pasted into one of the above-mentioned applications using one simple keystroke. Using the power and flexibility of the chosen application, high quality reports and presentations can be easily prepared. All plots can be saved in Windows Metafile format. These can be easily read by a word processing package or presentation graphics package and give the maximum flexibility for user customisation. All reports can be saved in TSV (Tab Separated Variable) format using the Export facility that means they will automatically be tabulated when read into the favourite spreadsheet. Enter a description and a command line for each application to be added to the PROSPER menu. The description is the data that appears on the menu. The command line is the full path name of the program to execute.
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Use the Browse buttons to browse for the application require. Use the Clear buttons to initialise the appropriate application information. 2.2.2.5 Limits The Preferences Screen is used to customise PROSPER to your particular requirements. Click on the appropriate tab at the top of the data entry section in order to change the option you require. Done
Click on this button to save you changes.
Cancel
Click on this button to discard changes made on all tabs in the current edit session..
Help
Click on this button to view this screen.
This tab allows you to specify Limiting Values for the following options.
For IPR Generation Maximum AOF for OIL Maximum AOF for GAS Maximum AOF CONDENSATE
for
RETROGRADE
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For Performance Curve Generation Minimum GLR Injected for GAP Performance Curves For VLP Generation You can control the display of large VLP values in SYSTEM and VLP calculations. Twice Reservoir VLP Pressure is only displayed is VLP Pressure Pressure less than twice the reservoir pressure Display Limit Unlimited VLP Pressure is always displayed For HSP System Calculations (within Design Screen) These options are used to control the iteration that searches for a solution for the Inflow/ Outflow intersection that ensures that the Pump and Turbine power are equal. HSP Rate Refinement Tolerance HSP Pump/Turbine Tolerance
Power
HSP Power Fluid Ratio HSP Power Fluid Divisor HSP Iteration Limit For Gradient Calculations Calculation Step Length Use Correlation Length
Step
User specified step length No
Use Program defaults for correlation step length
Yes
Use user-entered value for the step length used by correlations in nodal analysis
No
No documentation within TPD files
Yes
TPD files are documented with descriptions of all data. Use this option sparingly as it increases the size of the resultant files considerably.
For TPD Files
Document TPD Files
VLP MultiVariable Analysis Maximum Number of Rates
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This option defines the maximum number of rates that can be used to calculate the well VLPs
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of This option defines the maximum number of values that can be used for each sensitivity variable
2.2.2.6 Units
This tab allows to specify the default Units Systems to use for new files. If setting the option "Always Use Default Units" to "Yes", then the units displayed for any file read in will always be set to the default choice, regardless of the settings in the file. Units Database Directory: this is the location where the PROSPER Units database (PRPUNITS.PXDB) resides.With the browse button one can alter it. The free format number set the precision for all inputs and output data to free.
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2.2.2.7 Equipment
This option defines the default values for the Pipeline and Tubing Roughness that will be used in the Equipment Data. 2.2.2.8 VPC VPC stands for Valve Performance Clearinghouse. Done
Click on this button to save the changes.
Cancel
Click on this button to discard changes made on all tabs in the current edit session
Help
Click on this button to view this screen.
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For members of the VPC consortium, access to the VPC gas lift valve database is established through this screen.
2.2.3 Software Key Maintenance The Software Key command activates the Petroleum Experts Remote Utility. This program allows the user to see what programs are currently enabled, their expiry date, and user authorisation codes and key number - as can be seen in the screen shot below. This utility is also used to enter the authorisation codes that will update or activate the software key where necessary. For reasons of security, Petroleum Experts normally sends an inactive software device with the application program. The codes needed to activate or update the software key are sent separately by e-mail.
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This utility is also used to update the software key and to view versions. Software keys must be updated when new programs or modules are required or the key expiry date changed. Entering the Authorisation Code To enter the authorisation codes, click the Update button. The following screen will appear:
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Enter the codes that have been received from Petroleum Experts from left to right beginning with the top row. The easiest way to do this is to use the Paste button to copy the codes from the email sent by Petroleum Experts. Press Continue to activate the codes or Cancel to quit the code update. Updating the Software Protection Key Access to the software automatically ceases when the license expiry date has elapsed. The user is however, reminded several days in advance, which gives sufficient time to contact Petroleum Experts to obtain update codes. This occurs when either: The software license trial period has ended. The annual software maintenance fee is due. Software protection keys also need updating when one acquires new Petroleum Experts software packages. The procedure for updating the software key is the same as described above. When the appropriate screen appears, enter the codes provided from left to right beginning with the top row. Press OK to activate the codes, or Cancel to quit the update. To view the expiry date for any of the enabled programs, click on the software title. © 1990-2011 Petroleum Experts Limited
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When receiving new codes, always update every key that belongs to the company. Subsequent updates may fail if all previously issued codes have not been properly entered into the key. One can view the software key driver versions by clicking on the Versions button. The following screen will appear.
2.2.4 FileList Use this screen to search for PROSPER files anywhere in the system. Browse a directory, then enter the Patter (file format, for example: *.OUT to load all the PROSPER files) and then Load Files to visualise all the PROSPER files contained within the selected directory. Information about the files will be imported as well.
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2.2.5 Evaluate OpenServer Statement This option can be used to test the OpenServer commands and variables. In the Evaluate OpenServer screen a field is available where to input the OS string, which can correspond to a parameter or to a command:
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Type or Paste the OS string in the String field, then select one of basic OS commands (DoGet, DoSet, DoCommand), if required enter the Value (valid only if using DoSet) and click Evaluate to perform the function. In the Returned value it is possible to read the results of the operation. The buttons Commands, Variables and Functions will access the lists of the strings of the commands, input/output variables and functions Ü
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In the string lists screen it is possible to search for strings by using the Search function
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2.2.6 User Correlations PROSPER has been designed to accept outside calculation modules for fluid flow correlations, Equation of State PVTP calculations, choke models (pressure loss through restrictions), inflow performance calculations, HSP Gas Derating models, viscosity models. Users can obtain an authoring kit from Petroleum Experts to enable the building of a compatible Dynamic Link Library for use in PROSPER. Before a DLL can be accessed, it must first be installed into PROSPER. This is done by clicking File User Correlations. Select either Flow Correlation, Equation of State Model, Choke Correlation, Inflow Performance Model, HSP Gas DeRating Model, Viscosity Model. PROSPER will display a list of the currently installed DLLs of the selected type. To add a correlation, click Add and select the appropriate file from the file dialogue. Click OK and it will be imported into PROSPER. MODEL
EXTENSION
Flow Correlation
.COR
Equation of State PVTP Model .EOS © 1990-2011 Petroleum Experts Limited
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Choke Correlation
.CHK
Inflow Performance Model
.RSM
HSP Gas DeRating Model
.GDR
Viscosity Model
.VSM
Information about particular correlations (name, phases and flow regimes modelled, etc.) can be obtained by clicking the Info button. A screen similar to the following will be displayed.
2.2.7 Printer Setup 2.2.7.1 Preparing to Print There must be a properly installed and connected printer in order to print.
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The Printer Setup command of the File menu allows to select a printer and define its set-up options.
2.2.7.2 Selecting and configuring a Printer Select the correct printer from the list box provided. Only printers that have been installed under Windows will be displayed. The configuration of the printer follows the exact guidelines of any other software running under Windows.
2.2.7.3 Printing Export Data Prior to printing export data, it is always a good idea to save the data file(s). In the unlikely event that a printer error or some other unforeseen problem occurs, this simple procedure could prevent the work from being lost. To print export data, select the Output menu and the Export option. Select the sections to report on the dialogue box. The program will lead the User through a series of input screens to set up the required report sections. From the main dialogue box, select a destination for r data.
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The appearance of printed reports is controlled by the export data set-up options that have been set. Click Setup to display the following screen:
Select a suitable font and set the margins etc. that will be used for printed export data. Only non-proportional fonts are allowed in reports to maintain vertical alignment of the columns.
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PROSPER default font is recognised by most print set-ups. To avoid potential printing problems, always set up the system to use a font that is supported on the system prior to printing PROSPER export data for the first time.
Click OK to return to the output screen. Clicking Print initiates generation of the export data and sends it to the selected destination. Export data can be sent to the following entities: · Printer -
the primary printer as set up under Windows.
Creates an ASCII data file and saves it. Clicking Print will display a · File dialogue box that requests a file name and destination. Enter a suitable file name (the program automatically appends a ".PRN" extension) and click OK to save the file. The Fixed Format option saves a file in a printer ready format that can be imported into a DOS based word processor or text editor. Use the Tab Delimited format to save a file suitable for importing directly into a spreadsheet such as EXCEL. · Clipboard - Clicking Print after selecting this option copies the data onto the Windows clipboard. From the Clipboard, can view, edit and paste the data directly into another Windows application. E.g. a word processing program. Tab delimited data can be pasted directly into spreadsheets. Clicking Print after selecting this option allows to view the report on the · Screen screen. Scroll through the data using the scrolling thumbs or arrows. When finished viewing, click OK to return to the main menu.
2.2.7.4 Selecting an Exported Data to Print It is not necessary to be in PROSPER to print a report. Provided to have previously generated a report file (*.PRN), a report can be easily opened and imported into any word or spreadsheet program. If the Tab Delimited option was selected, this will allow the User to easily create tables and/or format the data using a word processor.
2.2.8 Word Processing in PROSPER The WordPad command on the File menu gives direct access to the Windows word processing package. This application can be used to make notes of the current analysis for later inclusion in reports. If no alternative word processing package is available, it is possible to use WordPad to edit, format and print the reports.
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2.2.9 Clipboard Command The Clipboard command on the File menu gives direct access to the Windows clipboard viewer. This feature is useful for checking data input or intermediate results from e.g. gas lift design calculations that are written to the clipboard by PROSPER.
2.2.10 Command Buttons The following command buttons are used in PROSPER.
All
This command button is used in the Equipment and Gas Lifted (safety equipment) option screens. It will select all input parameters and data points for automated editing.
Calculate Performs the various calculations on the input parameters for the correlations selected. Cancel
Returns to the previous screen. Any changes or modifications will be ignored by the system.
Continues to the next input screen. Any changes to the fields will be saved Continue and retained in memory for later calculations. A warning message will be displayed when fields requiring input data are left blank. Copy
To copy existing data points, select the line entries to duplicate and click on Copy. Next, select the destination line(s) and click on Copy again. Subsequent line entries will be not be overwritten by this operation.
Correlati Displays o the results of any matching performed under the VLP/IPR Match option. n s
Delete
This command button is used in the Equipment and Gas Lifted (safety equipment) option screens. It allows to delete individual or several data points. To delete, select the line entries to erase and click on Delete. If one wishes to delete all existing line entries, click All and then Delete. The program will clear the input screen.
Done
Returns to the previous menu. Any changes or modifications will be retained in memory by the program.
Edit
This command button is used in the main Equipment screen. One or more items can be modified at a time. When used with 'All', all items will be selected for editing.
Export
Brings up the Data Export interface. This will be specific to the data on the active window.
Help
Provides on screen help for PROSPER. For general information, press the 'ALT' and 'H' keys together in the Main menu, or the Index button under any
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help screen. Specific help screens are also available for each window. Import
Calls up the general import interface that allows to grab data from any text file. This button will usually be found where tabular data is to be input.
Insert
This allows to add one or several data points providing there are sufficient entry fields. Select the line number where to add a new entry and click on I nsert. The program will move existing line entries down to accommodate the inserted line(s).
Main
Returns to the Main Application Menu. Any changes or modifications will be saved and retained in memory by the program.
Match
Displays a variable screen where match data can be entered in order to adjust existing correlations to fit real data.
Move
Allows to re-arrange data points. Select the line(s) to transfer and click on Move. Next, select the destination line(s) and click on Move again. Subsequent line entries will be moved down to accommodate the transferred line(s).
Plot
Plots any calculated results and displays them on screen. Hard copies of the screen display can be printed by selecting the Hardcopy command button on the Plot screen.
Recall
Allows to recall an existing PVTP file. The User will be prompted for the directory and name of the file.
Report
Calls up the reporting interface with a report that is specific to the active window. This is generally found on windows that display the results of calculations. It is then possible to choose to print this report. The report is generated from a system report template.
Reset
Resets the Match parameters in order to reinstate the original textbook correlations.
Save
Saves a current PVTP file. If this is a new data file, the User will be prompted for a file name.
Summar Displays a summary screen of the input equipment parameters or system units. y The following command buttons are used in the Plot Menu and Plot screens.
Clipboard
Sends black and white or colour copies of the screen plot to the Windows Clipboard where it may be retrieved by a word processing program for inclusion in reports.
Colours
Allows to define the screen display colours of plot labels, scales, grids, etc.
Finish
Returns to the previous menu or screen.
Hardcopy
Generates black and white or colour print copies of the screen plot. It © 1990-2011 Petroleum Experts Limited
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is automatically sent to the device selected.
2.3
Labels
Allows to label plots. All plot labels are stored in memory and saved when Output files are generated.
Replot
Re-displays the original screen.
Scales
Allows to re-define the minimum and maximum values for the X and Y plot axes.
Data Input - General This section describes the PROSPER main menu and the input data required before an analysis can be performed. Data should be entered by working through the PROSPER menus following the logic order from left to right and top to bottom. The following menus are described in this section: · Main menu · Options menu
2.3.1 PROSPER Main Menu All PROSPER functions are listed as menu options. Simply select the required menu and choose an item from the list displayed. This will activate an option or display the relevant screen. Problem solving with PROSPER is approached systematically by working from left to right through the main menu. Calculation menus are activated only when the necessary input data has been entered. To start PROSPER, select the appropriate icon and press or double-click the program icon. A screen similar to the following will appear:
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The menu options across the top of the screen are the PROSPER main menu options. Each is described below. 2.3.1.1 File The File menu is a management menu with commands that enables to open, save or create new data files. It is possible to use this menu to define the default data directory, printer set-ups options and hook in external DLLs. A facility for accessing other Windows programs via PROSPER is also provided.
2.3.1.2 Options The Options menu is the starting point of PROSPER and the key to the program. Use this menu to define the application and principal well features such as - prediction method, artificial lift type and fluid type. The options selected are unique to the current file and apply until changed by the user, or another file is recalled. These options also determine the subsequent screens, menus and commands that are displayed.
2.3.1.3 PVT Use the PVT menu to define well fluid properties and select fluid property correlations. PVT correlations can be modified to match laboratory-measured data using a nonlinear regression technique. Alternatively, detailed PVT data may be entered in tables. © 1990-2011 Petroleum Experts Limited
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2.3.1.4 System The System menu is used to define the well's downhole and surface equipment as well as the reservoir inflow performance. When applicable, Gas Lift, ESP, HSP, PCP and other artificial lift methods equipment data are entered in this menu.
2.3.1.5 Matching The Matching menu allows comparison of field data with calculated pressure drops in well tubing and surface piping. All available correlations can be compared to allow selection of the model that best suits the field conditions.
2.3.1.6 Calculation The Calculation menu provides with the relevant calculation options. Calculations to determine well performance, pressure and temperature profiles in the wellbore, perform sensitivity analyses, make gradient comparisons and generate lift curve tables are available in this menu.
2.3.1.7 Design ESP, HSP, PCP, Jet Pumps, Sucker Rod Pumps, Multiphase Pumps sizing as well as gas lift mandrel placement and valve setting pressure calculations, coiled tubing and diluents injection are available from the Design menu. Access to the databases that hold gas lift valves, ESP, HSP, PCP, Jet pumps, Sucker Rod Pumps (NEW!!!) equipment characteristics is via the Design menu also.
2.3.1.8 Output The Output menu is used to generate reports, to export data and to plot data. Report templates are provided and user templates can also be defined. The data used can be input data, analysis data, results or plots. Reports can be saved in various file formats (RTF, TXT and native) and can be displayed or sent to a printer. Export data can be viewed on screen, sent to the Windows clipboard, sent to a printer or saved in a file. Plots can be printed directly, saved to a report file or a Windows metafile. Selected plots can also be sent to the clipboard where they can be retrieved by other Windowsbased programs.
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2.3.1.9 Wizard This menu accesses the wizard area of PROSPER. This allows to Create/Edit and Run wizards that allow the User to build and run models step-by-step guided fashion.
2.3.1.10Units This menu is used to define the input and output units of measurement. A flexible system of units is provided allowing to customise the internal units system.
2.3.1.11Help Provides on-line help for PROSPER. The User can get help on specific tasks, fields or commands. Help is also given on the keyboard and miscellaneous Windows commands.
2.3.2 Options - Options Selection The Options menu is used to define the characteristics of the well. The options selected establish the input data required and the calculation options available. The selections made apply to the current session. The data entry screens, input fields and variables are limited to those relevant to the particular application. Input options may be changed at any stage of the processing. New choices may require other information to be supplied. Therefore the User is advised to ensure that all relevant input is still valid for the new option selection. To access the Options menu, point to the menu name and click the mouse or press ALT+O. The following data entry screen will appear:
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The entry screen is divided in two main sections - System options and User information. Under the System options section, define the well characteristics such as fluid type, well completion, lift method, etc. These selections determine information that will be required to enter later. The lower section of the screen comprises the header information and comments that identify the well and will appear on the report and screen plot titles. Option Selection To select an option, click on the arrow to the right of the required field. The list of available choices will be displayed.
2.3.2.1 Fluid Description
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2.3.2.1.1 Fluid Type · Oil and Water (Black Oil Model or Compositional) Oil and/or Water fluids · Dry and Wet Gas (Black Oil Model or Compositional) Dry and Wet Gas is handled under the assumption that condensation occurs at the separator. The liquid is put back into the gas as an equivalent gas quantity. The pressure drop is therefore calculated on the basis of a single-phase gas, unless water is present. · Retrograde Condensate (Black Oil Model or Compositional) This fluid type accounts for the condensate drop out in the tubing.
2.3.2.1.2 Method · Black Oil This option uses industry standard Black Oil models. Five correlations are available for oil producers. For gas condensate systems an internally developed model is used. These correlations can be adjusted to match measured data using non-linear regression. · Equation of State Reservoir fluid is modelled by pseudo components having user-specified properties. The two equation of state models Peng-Robinson and SoaveRedlich-Kwong are available in PROSPER to predict PVT properties. User EoS DLLs can also be linked into PROSPER.
2.3.2.1.3 Equation of State Setup This button is active when Equation of State Method has been selected and can be used to access all the options related to the use of the Equation of State: ·
EoS Model (Peng-Robinson or Soave-Redlich-Kwong)
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Optimisation Mode (None, Low and Medium)
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Volume Shift enable/disable
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Reference Pressure and Temperature
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Path to Surface and Recycle: Flash Straight to Stock Tank, Use Separator Train, Use K values
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Target GOR Method (Use Separator Fluids or Use Fluid from PSAT)
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2.3.2.1.4 Separator ·
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Single Stage This option is available for black oil option for following fluids: · Oil and water · Dry and Wet Gas Two Stage This option is available for Black oil model in case of Oil and Water fluid type only. Separator and tank properties are entered and recombined by PROSPER.
Multi-Stage This option is available for: - Retrograde Condensate Black Oil model - Equation of State Method Up to 10 stages of separation can be modelled for compositional applications. ·
2.3.2.1.5 Emulsions · No or Emulsion + Pump viscosity correction Select Emulsion + Pump viscosity correction to allow input of Emulsion viscosity in the PVT section. This option must be selected to turn on pump viscosity corrections.
2.3.2.1.6 Hydrates · Disable Warning or Enable Warning Select Enable Warning to allow flagging of hydrates formation in calculation screens. To use this feature, go to the PVT section and enter or import the hydrates formation table.
2.3.2.1.7 Water Viscosity · Use Default Correlation or Use Pressure Corrected Correlation When the default correlation is used, the water viscosity will be sensitive to the water salinity and temperature. When the pressure corrected correlation is used, the water viscosity will be sensitive to the water salinity, temperature and pressure. These correlations to predict water properties (e.g. viscosity) can be found in McCain's "Properties of Petroleum Fluids", chapter on Oil Field waters. The Pressure corrected model is based on Fig, 24-8, Bradley et al., Petroleum PROSPER Manual
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Engineering Handbook, SPE, Dallas, 1987. The viscosities of oilfield waters at reservoir conditions are low, virtually always less than one centipoise. Water Viscosity does not vary greatly with pressure because the small amount of gas dissolved in the water has small effect on its viscosity. 2.3.2.1.8 Water Vapour · No Calculation or Calculate Condensed Water Vapour This option is available for Dry and Wet Gas and Retrograde Condensate fluid types with PVT Black Oil model. If ‘Calculate Condensed Water Vapour’ is selected, the condensation of water vapour will be taken into account when performing pressure drop calculation. The calculated moisture contents of natural gases is based on the equations of Bukacek (Equilibrium Moisture Content of Natural Gases, Research Bulletin Vol 8, Institute of Gas Technology, Chicago USA, 1955). The correlation on which these calculations are based is accurate to within five percent. This was developed for dry gases. The presence of heavier hydrocarbons in wet gases and retrograde condensates increases the water content by as much as ten percent at 1000 psia and twenty percent at 10,000 psia. 2.3.2.1.9 Viscosity model By default the fluid is considered Newtonian. If desired, non-Newtonian effects can be modelled by selecting Non-Newtonian and entering in the PVT section rheologic properties of the fluid. 2.3.2.2 Well 2.3.2.2.1 Flow Type · Tubing Flow This option models flow through a circular cross sectional area (flow in tubing/ pipe) · Annular Flow This option models production up the casing / tubing annulus · Tubing + Annular Flow This option models production up the tubing, the annulus space, or tubing and annulus simultaneously
2.3.2.2.2 Well Type · Producer this option model production wells Injector · This is a generic injector well. The fluid to be injected can be specified by the User. Gas injectors can be modelled by selecting this option © 1990-2011 Petroleum Experts Limited
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· Water Injector Injection of single-phase water CO2 Injection The best approach to model CO2 Injection is to use an Equation Of State PVT Model and set the Fluid Type as "Retrograde Condensate" and not "Dry And Wet Gas". The reason behind this is that the "Dry And Wet Gas" models considers the fluid as a single phase throughout the entire system and modifies the gas properties to account for the condensate. The "Retrograde Condensate" model assumes multiphase flow modelling allowing for gas and/or liquid phases to be present anywhere in the system (depending on the prevailing pressure and temperature). N.B. In CO2 Injection, depending on the conditions of pressure and temperature, it is possible to have phase changes somewhere in the system (Gas-.Liquid->Gas) The Gray (and Modified Gray) correlation uses its own internal PVT calculator that overrides the Prosper-calculated pvt properties and therefore this should not be used to model CO2 Injection.
2.3.2.3 Artificial Lift 2.3.2.3.1 Method The following artificial lift options are available when Oil is selected as a fluid type. · None No artificial Lift selected · Gas Lift (continuous) Three different approaches are provided. Annular gas lift is handled by PROSPER. If the Flow Type is Annular Flow and a Gas Lift method is selected, then PROSPER automatically switches to model gas injection down the tubing, and production up the annulus Options available: No Friction Loss in the Annulus, Friction Loss in the Annulus, Safety Equipment · Electrical Submersible Pump An ESP installation can be analysed or designed using this option · Hydraulic Drive Downhole Pump A HSP installation can be analysed or designed using this option · Progressive Cavity Pumps A PCP installation can be analysed or designed using this option · Coiled Tubing Gas Lift PROSPER Manual
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Coiled Tubing with gas lift can be analysed or designed using this option · Diluent Injection Injection of a given rate of diluent in the tubing can be modelled · Jet Pump A Jet Pump installation can be analysed or designed using this option · Multiphase Pump Framo multiphase pump can be analysed · Sucker Rod Pumps A Sucker Rod Pump installation can be analysed and designed Gas Lift (Intermittent) · PROSPER can be used to design and model the performance of wells with intermittent gas lift
2.3.2.3.2 Type If Gas Lift is the chosen method, then the following types are available. · No Friction Loss In Annulus It is the classic approach for the annulus gas gradient. The pressure drop due to friction in the annulus is ignored and the gas gradient is determined by the top casing pressure and the temperature profile. · Friction Loss In Annulus The pressure drop due to friction in the annulus is taken into account, but the top casing pressure is assumed constant. If this option is selected the tubing equipment screens will automatically change and require tubing OD and casing ID data to be entered. · Safety Equipment Surface delivery lines, chokes, the gas lift injection string and safety valves in the annulus are taken into account. Top casing pressures will change with injection rate. If Hydraulic Drive Downhole Pump is the chosen method, then the following types are available. · Commingled Annular Supply The power fluid for the turbine is supplied via the annulus and returns to surface, commingled with the produced fluid via the tubing. · Commingled Tubing Supply The power fluid for the turbine is supplied via the tubing and returns to surface, commingled with the produced fluid via the annulus. · Closed Loop Supply © 1990-2011 Petroleum Experts Limited
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The power fluid for the turbine is supplied via the outer annulus and returns to surface via the inner annulus. The reservoir fluid is produced through the tubing. There is no commingling of produced and power fluids. If Progressive Cavity Pump is the chosen method, then the following types are available. · Sucker Rod Drive The program will assume to have a surface drive head from which require rods in order to move the rotor across the pump. · Downhole motor drive The program assumes to have a downhole motor instead of surface drive motor. If Coiled Tubing Gas Lift is the chosen method, then the following types are available. · No Friction Loss in Coiled Tubing Friction losses along the coiled tubing are neglected. · Friction Loss in Coiled Tubing Friction losses along the coiled tubing are accounted for. If Diluent Injection is the chosen method, then the following types are available: · Tubing Injection-Annular Production The power fluid is injected in the tubing and the production flows through the annulus · Annular Injection-Tubing Production The power fluid is injected in the annulus and the production flows through the tubing If Jet Pump is the chosen method, then the following types are available: · Tubing Injection-Annular Production The power fluid is injected in the tubing and the production flows through the annulus · Annular Injection-Tubing Production The power fluid is injected in the annulus and the production flows through the tubing If Multiphase Pump is the chosen method, then the following types are available: · Framo Pumps
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2.3.2.4 Calculation Type 2.3.2.4.1 Predict The program is capable of predicting either pressure only or pressure and temperature changes simultaneously. · Pressure Only If this option is selected, the flowing temperature profile must be entered. This calculation option is fast and can provide accurate pressure profiles, however, it does not account for changes of temperature due to variation of operating conditions. · Pressure and Temperature (On Land and Offshore) This option will calculate both pressure and temperature profiles using the method specified in Temperature Model.
2.3.2.4.2 Model Three models for temperature calculations are available: ·
Rough Approximation Calculates the heat loss from the well to the surroundings using an overall heat transfer coefficient, the temperature difference between the fluids and the surrounding formation and the average heat capacity of the well fluids. The geothermal gradient entry screen is used to input formation temperatures (e.g. from logging runs) at measured depth points. A minimum of the surface and first node temperatures are required. Temperatures entered should be the extrapolated static temperatures, and should not be confused with the entry of measured flowing temperatures required for the Predicting pressure only case. The Rough Approximation temperature model requires calibration using measured temperature data. It is not accurate in a predictive mode.
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Enthalpy Balance This rigorous thermodynamic model considers heat transfer by conduction, radiation, and forced and free convection. Heat transfer coefficients are calculated using values held in a user-definable database. The temperature prediction calculations are transient, allowing sensitivities against flowing time to be run. This temperature model requires considerably more input data and computation time for either Predicting Pressure Only or the Rough Approximation temperature model. The production riser is properly taken into account. Therefore the heat loss prediction between the seabed and wellhead will be accurate. Due © 1990-2011 Petroleum Experts Limited
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to increased computation times, we recommend that this option be used only when temperature prediction rather than pressure loss is the required result (for e.g. process calculations and material selection). The Enthalpy Balance temperature model is capable of accurate flowing temperature prediction for a wide range of conditions. The temperature prediction is useful for generating temperature profiles in: · long pipelines · subsea wells · high pressure/temperature exploration wells · predicting temperature/pressure profiles to help predict wax/ hydrate deposits. · These models also account for Joule-Thompson Effects. The temperature calculation must commence from a known condition. This is usually the reservoir pressure and temperature. As a consequence, calculating from a downstream node (unknown temperature) to an upstream node (known temperature) is not meaningful · Improved Approximation As the Enthalpy Balance model, this is also a full enthalpy balance pressure and temperature prediction model, with the difference that the term of the enthalpy balance concerning the heat exchange with the surroundings (which includes free and forced convection, conduction and radiation) is simplified by a heat loss term characterised by an overall heat exchange coefficient. For this reason data related to the completion hardware and thermal properties are not necessary. Like any enthalpy balance model, Joule-Thomson Effect is also accounted for. These characteristics make this model particularly useful when an accurate calculation of temperature is sought for and only a few data on the completion are available. The geothermal gradient entry screen is used to input formation temperatures (e.g. from logging runs) at measured depth points. A temperature gradient in the sea can be entered for offshore applications. A minimum of the surface and first node temperatures are required. Temperatures entered should be the extrapolated static temperatures, and should not be confused with the entry of measured flowing temperatures required for the Predicting pressure only case. The Improved Approximation temperature model requires calibration using measured temperature data. It is not accurate in a predictive mode. PROSPER Manual
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2.3.2.4.3 Calculation · Full System Calculations for pipelines, tubing and reservoir · Pipeline Only Calculations for pipelines only
2.3.2.4.4 Output · Show calculating Data During a calculation it displays the calculated values · Hide calculating Data Select Hide to speed up calculations by not updating calculation screen displays. This will automatically be set to Hide when run from GAP
2.3.2.5 Steam Calculation NEW!!! When the fluid type is set to Oil & Water and one of the enthalpy balance models (Improved Approximation or Enthalpy Balance) is selected, the option to enable/disable the steam calculations is available. · No Steam Calculations · Allow Steam Calculations
2.3.2.6 Well Completion 2.3.2.6.1 Type · Cased Hole or Open Hole This selection determines the appropriate IPR Completion models to use. In particular Cased Hole enables the availability of Skin models to calculate the skin factor, whilst Open Hole disables the availability of Skin models.
2.3.2.6.2 Sand Control · Five options are currently available: None · Gravel Pack · Pre-Packed Screen · Wire Wrapped Screen · © 1990-2011 Petroleum Experts Limited
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Slotted liners
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2.3.2.7 Reservoir 2.3.2.7.1 Type ·
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Single Branch This option allows to model single branch IPRs. The IPR screen comes with various standard inflow models from which the user selects one. Multilateral Well Enables the Multilateral IPR model. For the multi-lateral selection, the IPR screen requires detailed drawing of the downhole completion.
2.3.2.7.2 Gas Coning · Yes or No Rate dependant GOR will be modelled and calculated when Yes is selected. This option is only available for Single Branch type wells.
2.3.2.8 User Information and Comments These fields are optional. The details entered here provide the User information that identifies the well model in the screen plots and printed reports. The Comments area is used to enter free format text describing the details of the analysis. A Date stamp feature is provided to mark either the comment text or the header data for future reference. We recommend that comments be used to summarise any assumptions made in the analysis. Whenever an existing model is modified, appending a summary of changes and a date stamp will greatly assist current and future users working with the file. This information can be displayed on the main PROSPER screen by selecting the appropriate option in the Preferences Section (Main Screen Tab - Status screen option).
2.3.3 Options - Perforating Gun DataBase Under | Options | Perforating Database, a database for perforating guns is accessible. The gun database initially originates from SPOT (Shell Perforating Optimisation Tool) and permission was granted for its implementation into PROSPER.
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Like other databases in PROSPER, the user can add, delete and amend the inputs in the gun database. A filter allows to select guns by: - vendors, - Gun OD - Gun types - Minimum restriction and - Tolerance. The following section was taken from the SPOT help file and is published with permission from Shell: The gun database contains API 19-B1 and API RP 43 Section I Data for perforating guns available from: ·
Baker Hughes Incorporated (Baker)
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Schlumberger (SLB)
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·
Dynawell (DYNA)
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Innicor Subsurface Technologies (INNICOR)
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Owen Oil Tools (Owen)
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Explosivos Technologicos Argentinos (ETA)
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GEODynamics (GEODynamics)
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Titan (TITAN)
Companies were provided with an opportunity to adjust/ update data in the SPOT Gun Database. It is recommended that Users cross check all critical information with the appropriate perforating manufacturer/ service company before a gun type/ completion method is selected. Sections I to IV of API 19-B are summarised below: ·
Section I - firing a fully-loaded gun section under ambient conditions into a standard casing and cement target;
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Section II - firing a single charge under pressurized conditions into a stressed rock sample;
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Section III - firing a single charge into a metal target at elevated temperature;
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Section IV - firing a single charge into a stressed rock sample under simulated wellbore and reservoir conditions, then measuring the flow performance of the perforated sample relative to its performance prior to shooting;
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Section V2 - measuring the amount of debris retained within a fired fully-loaded gun section in order to calculate how much debris will be introduced into the wellbore per foot of gun;
It should be noted that API RP43 preceded API RP19B. The American Petroleum Institute (API) Perforating Subcommittee adopted API RP19B during November of 2000, and state that API 19B “is the only document that API recognizes as valid in this program.” As API 19B data is not available for all gun systems, API RP43 data has also been included in the database (data sources are clearly marked). Although API RP43 is not officially valid, Section 1 testing for both API RP43 and API 19B is based on concrete targets. As concrete is not representative of reservoir rock, API 19-B and API-RP 43 Section 1 data is converted to downhole conditions in SPOT using Shell proprietary correlations (based on laboratory research). Although these correlations should provide a reasonable estimate of perforation characteristics in reservoir rock under downhole conditions, a better estimate of perforation performance can be obtained by conducting
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reservoir specific Section II (firing a single charge under pressurized conditions into a stressed rock sample) and/or Section IV tests (firing a single charge into a stressed rock sample under simulated wellbore and reservoir conditions, then measuring the flow performance of the perforated sample relative to its performance prior to shooting). If Section II or Section IV data is available, it can be entered into the SPOT “Vendor Database” under the Section II/Section IV Data heading. If the concrete strength during the API RP 19B or API RP43 test is not recorded in the Gun Database, in accordance with the minimum allowable strength specified in API RP 19B, a briquette strength of 5000psi is assumed in SPOT calculations. ___________________________________________________________________ ___________________________________________________________________ __ 1. API Recommended Practice 19-B, “Recommended Practice for the Evaluation of Well Perforators”, 1st Edition, 28 Sep 2001 2. To be introduced in the next revision of RP 19-B, a draft of which is with API for review at the time of writing.
2.3.4 Options - Tubing DataBase Under | Options | Tubing Database, a comprehensive tubing data base is available in PROSPER:
The database is also accessible from the down hole equipment screen so that the user © 1990-2011 Petroleum Experts Limited
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can select any tubing from the database directly to be used for the description of the down hole equipment.
2.3.5 Options - Casing DataBase Under | Options | Casing Database, a comprehensive casing database is available in PROSPER:
The database lists casing manufacturer, type, specification, seal, Casing OD, casing weight, Casing ID and wall thickness. The database can be accessed from the down hole equipment input screen. From the down hole equipment screen, the user can select any casing available in the database and use it directly for the description of the well bore.
2.3.6 Options - Pipe Schedule Under | Options | Pipe Schedule, a comprehensive pipe database is available in PROSPER:
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The database lists nominal pipe size, pipe OD, Iron Pipe Size, Steel schedule number, wall thickness and pipe internal diameter. The pipe database can be accessed from the surface equipment input screen. From the surface equipment input screen, the user can select any pipe available in the database and use it directly for the description of surface pipes.
2.4
PVT Data Input
2.4.1 Introduction To predict pressure and temperature changes from the reservoir, along the well bore and flow line tubular, it is necessary to accurately predict fluid properties as a function of pressure and temperature. The User must enter data that fully describes the fluid properties or enables the program to calculate them. There are four possible approaches: - Correlations: Where only basic PVT data is available, the program uses traditional black oil correlations, such as Glaso, Beal, Petrosky etc. A unique black oil model is available for condensates and details of this can be found later in this guide as well as © 1990-2011 Petroleum Experts Limited
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the PROSPER manual. - Matching: Where both basic fluid data and some PVT laboratory measurements are available, the program can modify the black oil correlations to best-fit the measured data using a non-linear regression technique. - Tables: Where detailed PVT laboratory data is provided, PROSPER uses this data instead of the calculated properties. This data is entered in table format (PVT tables), and can be supplied either manually or imported from an outside source. So called black oil tables can be generated from an EOS model and then be imported and used in PROSPER. - Compositional: Where the full Equation of State description of the fluid is available and all the PVT can be obtained from a Peng-Robinson or a Soave Redlich Kwong description of the fluid phase behaviour. Note with regards to the PVT definitions: Use of Tables: Tables are usually generated using one fluid composition which implies a single GOR for the fluid. This will therefore not provide the right fluid description when we have injection of hydrocarbons in the reservoir or when the reservoir pressure drops below the bubble/dew point. Use of EOS: The equations of state are models that need to be matched to measured lab data (PVT lab report). Care has to be taken in order to make sure that the EOS has been matched and is applicable for the range of Pressures and Temperatures to be investigated. The program also allows fluid properties to be calculated and plotted for specified pressure and temperature ranges. The PVT menu has three options - Report, Input and Export. Select Report to inspect previously entered data, Export to save data to a text file, or Input to set up a new problem or edit an existing one. Recommended Steps Only Limited PVT Data Available (Minimum required for correlations) · Enter data as requested on PVT input data screen and select correlations that are known to best fit the region or oil type. Limited PVT Data and Laboratory Measured Data Available · Enter the basic black oil data requested in the PVT input data screen. · Enter PVT laboratory data in the Match Data data menu. The laboratory PVT data and the fluid properties entered on the data input screen must be consistent. Flash Data must be used. Up to 5 tables of laboratory measurements made at different temperatures may be entered. Use the T ables buttons to switch between tables. Click OK to return to the PVT input PROSPER Manual
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screen. · At this point it is possible to Calculate PVT properties using a correlation and Plot the calculated and match data to see how closely the non-optimised correlation fits. · Select Regression, then Match All. A non-linear regression will be performed to best fit each correlation to the measured lab data. Once the calculation is finished, select Parameters and identify the correlation that best fits the measured data. This correlation should then be selected and this modified correlation will be used in all further calculations of fluid property data. The fit parameters are the multiplier and shift applied to the correlation in order to fit the lab data. If the correlation were a perfect fit to the match data, Parameter 1 would be set to 1.0 and Parameter 2 would be zero. · In order to see how well the tuned correlations fit the data, on the regression screen there is plot utility, which will plot the variable values from the matched correlations, and the data entered simultaneously, to allow the User to see how good the fit is. Select Plot to display both the calculated and measured PVT data. Select the Variables option on the plot menu bar to choose the fluid property data to display.
2.4.2 Black Oil - Oil and Water 2.4.2.1 Input Data Select the PVT Input option from the main menu to display the following PVT Input data screen:
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Enter the required data in the fields provided. Movement from one box to another can be done using the TAB key. Next, select a Pb, Rs and Bo correlation and a viscosity correlation to use then click OK. Ü
Enter the oil solution GOR. This should not include free gas production. For gas production in wells producing injection or gas cap gas the solution GOR should still be entered. The balance of “free” gas production is accounted for elsewhere.
Mole Percent CO2, N2 and H2S refers to the separator gas stream composition. The impurities are used to correct the Z factor of the gas on the basis of the Wichert Aziz modifications for CO2, N2 and H2S. CO2 Injection Ü
When an "Oil and Water" model is used to describe the fluid, the viscosity correlation used by default for gas viscosity calculations is the Lee correlation.
For some details about the input parameters, refer to the Glossary (Appendix E).
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2.4.2.1.1 Black Oil Compressibility Calculation · Water compressibility is a function of salinity, temperature, and the volume with respect to pressure (reservoir pressure in this instance). · Specifying the water salinity and any impurities (H2S, CO2 and N2) allows black oil correlations to generate PVT parameters: specifically the water FVF (Bw). · From the water FVF the compressibility of water is directly back calculated (cw). · The equations used for the water FVF are those available in the following two papers: o Craft & Hawkins (1959), page 131, Petroleum Reservoir Engineering o Numbere, Brigham, and Standing (Nov 1977), page 16, physical properties of petroleum reservoir brines, by the petroleum institute of Stanford university. The conversion from Bw to Cw is as follows; · o 2.4.2.2 Tables In PROSPER the PVT data can also be entered as tables by clicking Tables from the main PVT input screen. Up to fifty separate tables may be entered, each at a different temperature. The program will use the data from the tables in all further calculations provided the Use Tables option has been selected on the input data screen. This option should be used only when extensive table data is available for a range of temperatures.
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Rather than entering the values by hand, PROSPER can read in tables of Black Oil PVT properties. To do this, click the Import button from the Tables screen, and PROSPER will prompt for the name of an ASCII file containing the PVT data. Petroleum Experts’ PVT Package PVTp can be used to calculate and export Black Oil PVT tables. An example of the PVT Table import file format is given in Appendix D. Alternatively, data can be passed directly from Excel on a table-only basis using the Clip button. The Clip button will paste the copied data from Excel into the selected PVT table. Ü
PROSPER interpolates the entered table data and if the entered data is incomplete i.e., one table containing only a single row of values will result in interpolation errors.
Information on how to import the data from a ASCII File can be found in Appendix F Importing Data from Text Files. Clip This option allows to import and export data from/to the Clipboard or export the tables to Printer, Screen, etc.
2.4.2.3 Match Data Click the Match Data button and enter PVT laboratory measured data to match to as shown on the example screen below:
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Since gas evolution in the tubing is a constant composition process, Flash data, not differential liberation data should be used for matching. For each match data table, enter the temperature and bubble point, then enter pressure versus gas oil ratio, oil FVF and oil viscosity. Where data is incomplete or not available, leave the field blank. Use the GOR and FVF at bubble point plus the viscosity if available. Enter only the minimum number of points to ensure a good match. Ü
Where only differential liberation PVT data is available, a PVT simulation program like Petroleum Experts' PVT package PVTp can be used to calculate the flash properties using a model that has been matched to the lab data.
Better results for sparse laboratory PVT data sets are usually obtained using correlations matched to the available lab data rather than using a PVT table lookup. Clip This option allows to import and export data from/to the Clipboard or export the tables to Printer, Screen, etc.
2.4.2.4 Regression This option is used to perform the non-linear regression, which adjusts the correlations to best-fit laboratory measured PVT data. The non-linear regression matching technique can be used on up to five PVT match tables, each with a different © 1990-2011 Petroleum Experts Limited
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temperature. The following PVT properties can be used as match variables: Pb Bubble point pressure. GOR Gas oil ratio versus pressure. Oil FVF Oil formation volume factor versus pressure. Oil viscosity Oil viscosity versus pressure. It is not necessary to match on all properties for all applications. In cases where the PVT data is incomplete or of poor quality, better results can often be obtained by matching on the best characterised parameters only. However, because bubble point can be difficult to accurately predict from correlations, it is recommended that, where possible, it is used as a match parameter. The minimum data required to perform a regression match is the bubble point and GOR.
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The form of the correlations for FVF is different above and below the bubble point. If the FVF at bubble point is not available, the regression may not achieve good results. When matching the oil FVF, always enter data at the bubble point. Do not enter many match points only use the minimum number to define the shape of the correlation curves. In most cases, only data at the bubble point is required.
2.4.2.4.1 Match From the Regression screen, individual correlations can be matched to selected measured PVT data by: · Selecting the correlations · Selecting the fluid properties to match to · Clicking Match
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2.4.2.4.1.1 Match All
All correlations can be matched to all the fluid property data in one keystroke by selecting the Match All command button.
2.4.2.4.1.2 Parameters
Having performed the matching process, the match parameters are displayed by clicking the Parameters button. The non-linear regression technique applies a multiplier - Parameter 1, and a shift - Parameter 2 to the correlations. The standard deviation is also displayed, which represents the overall closeness of fit. The lower the standard deviation, the better the fit. The best overall model is the one that has Parameter 1 closest to unity. The Parameters button displays the PVT correlations parameters screen. This shows the match parameters and the standard deviation for each matched correlation. Use these statistics to select the best correlation for the data set and conditions pertaining to the application. A plot should be made (refer calculation and plot sections) and a visual check of the fit quality performed before making the final correlation selection. The match parameters can be reset i.e. returned to the un-matched state by selecting the reset option. The following is an example of a correlation parameters screen:
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The standard correlations do not always accurately model the FVF above bubble point (especially for heavy or waxy oils). Additional match parameters (Parameter 3 and 4) have been introduced to allow the FVF to be independently tuned below (P1 and P2) and above (P3 and P4) the bubble point. In all circumstances, always enter match data at the bubble point to ensure that no discontinuities occur.
2.4.2.5 Correlations This options displays the match parameters and standard deviations for each matched correlation. See the Match section for a more detailed explanation.
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2.4.2.6 Calculate In order to make a plot or listing of fluid property data, PROSPER must first calculate the values over a specified range of temperatures and pressures. Using the calculated data points, plots of fluid properties versus temperature or pressure can be generated. The following is an example of the PVT Calculations screen. If the correlations have been matched, then the fluid properties will be calculated using the modified correlations. Ü
The calculation procedure is optional and used only to generate fluid property data for display and quality control purposes. During the computation of a pressure traverse, PROSPER calculates fluid properties at each pressure and temperature step or node as required by the application.
2.4.2.6.1 Calculating PVT Data The Calculate button access the PVT calculator, which can be used to perform calculation of PVT properties with varying Pressure and Temperature.
To generate tables and plots of PVT data: · Select Correlations (use the best matched one) · Select Automatic generation of Data Points · Enter the temperature range and number of steps · Enter the pressure range and number of steps · Click OK · Click Calculate to compute PVT data for the entire range of pressures and temperatures required by the modelling application. The following calculation screen will be displayed:
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The PVT section can be used as a convenient calculator by entering User selected data points, then entering specific temperatures and pressures to calculate fluid properties.
2.4.2.6.2 Displaying the Calculated Data on the screen The calculated data is displayed on the screen as default. Options to choose the calculated variables to be displayed are available by using Layout button in the PVT Calculation Results screen. Selecting Layout displays the list of all calculated variables that can be selected to customise viewing.
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2.4.2.6.3 Plotting the Calculated Data The calculated data can be displayed on a plot. The variables, which are plotted, are defined under the Variables option on the plot. After performing a PVT calculation click Plot from the PVT calculation screen. Display the selected results by following this procedure: · Click Variables. · Select Pressure for the X-axis. · Select GOR for the Y-axis. · Click OK to display a plot showing both the calculated values and the measured values similar to the following:
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Carefully examine the PVT plots for consistency with the match data. If necessary, select a different correlation and repeat the PVT calculations until satisfactory results have been obtained.
2.4.2.6.4 Saving PVT tables from Calculated Data The calculated data can be saved in the form of .ptb files by the button Save PTB provided at top of the calculation results screen. There is also the possibility of transferring the displayed calculation to the Tables by pressing on the Tables button.
2.4.2.7 Save the PVT Data This option allows a PVT data set to be saved under a separate name. A dialogue box will appear prompting to name the PVT file. The PVT extension is automatically provided by the program. If this step is omitted, the program will automatically save the (matched) PVT data in a .PVT file with the same name as the input (.SIN) file. 2.4.2.8 Open This option allows a previously saved PVT data set to be recalled into the open file. A dialogue box will appear prompting to select a PVT file. If this step is carried out after recalling a .SIN file, this will overwrite the PVT data from the original file. Ü PROSPER Manual
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first. This will save time and reduce the potential for error by recalling the relevant PVT data into each well file.
2.4.2.9 Composition In the PVT Input Data screen, click the Composition button, and PROSPER will use the PVT properties (Oil Gravity, GOR) to estimate the composition of the reservoir fluid. The estimated composition is used internally by PROSPER to calculate thermodynamic properties needed in the choke and enthalpy balance temperature models. This estimation of the composition is based on the method developed by TOTAL Ltd. (France). The following is an example of an estimated Black Oil composition:
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Estimation of reservoir fluid composition is available for Oil and Retrograde Condensate fluids.
2.4.2.10Emulsions If Options | Emulsions is selected PROSPER allows selection of the emulsion occurrence in the system from the PVT input dialogue. This tells PROSPER where the viscosity corrections will take place during calculation The Flowline Emulsion Data button opens the Emulsion Data entry screen. Water cut can be entered at this point that will then be used to calculate the emulsion viscosity in the PVT calculation section. 2.4.2.10.1 Emulsions PROSPER can model the effect of Oil/Water emulsions on mixture viscosity for Black Oil PVT systems. The behaviour of emulsions in producing well equipment is not well understood. Emulsion PVT in PROSPER provides a means to assess possible effects of increased emulsion viscosity by curve fitting experimentally determined data. It must be emphasised that the method is empirical and does not represent any rigorous model of emulsion behaviour. In the laboratory, stable emulsions can be prepared from many crude oil / water systems. Emulsion samples discovered in surface separation equipment do not necessarily imply that emulsions are present in the well. Field experience shows that the effect of emulsions is usually less than predicted by laboratory tests. Emulsion PVT should be used with caution and only when it is certain that emulsions are present and it is necessary to evaluate their effect on calculated pressures. PROSPER Manual
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To enable emulsion PVT in PROSPER, the Emulsion option must first be selected on the Options screen. Emulsion viscosity will replace the mixture viscosity for selected elements of the production system. Experimental or empirical emulsion viscosity data can be entered and curve-fitted using non-linear regression. The fitted curve is used to optionally replace the oil/water mixture viscosity in IPR, VLP and pump calculations. When selected, emulsion viscosity for the User-entered value of water cut will be substituted for the fluid mixture viscosity. Drop down the Emulsion box and select from the following: · No viscosity corrections Turns off emulsion viscosity corrections · Everywhere Emulsion viscosity for IPR, VLP and pump if present · Tubing and Pipe Emulsion viscosity for casing, tubing and pump if present · Pump only Emulsion viscosity for pump only · Pump and Above Emulsion viscosity in pump and tubing above pump · Tubing + Pipe (not pump) Emulsion viscosity in tubing and pipe only The selection of system elements affected by emulsion can be changed at a later time Ü
Even if No Emulsion Corrections has been selected on the PVT screen, pump viscosity corrections will be applied whenever Options Emulsions is selected. Produced fluid viscosity, not emulsion viscosity, will then be used for corrections.
To set up the emulsion model, select Emulsion Everywhere, (otherwise emulsion viscosity will not be active for the PVT calculations) then click the Emulsion Data button and the following screen will be displayed.
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The screen is divided into 3 sections: · Emulsion Data
Experimental data for matching
· Experimental Parameters
Experimental base conditions
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Match Parameters
Results of regression
The pressure and temperature that correspond to the experimental conditions are entered in Experimental Parameters. This enables PROSPER to correct the emulsion viscosity for temperature and pressure. Ü
Emulsions Everywhere must be selected before plotting the emulsion viscosity curve. The emulsion viscosity entered for zero water cut should be compatible with the 100% oil viscosity at the experimental temperature and pressure.
Emulsion viscosity is modelled as a function of water cut in 3 stages: · Sharp increase at low water cut · Plateau with a constant maximum viscosity for intermediate water cuts · ‘Tail’ that declines to the viscosity of water after the plateau The parameters Left and Right Water Cut for Maximum Viscosity define the maximum plateau region. To calculate emulsion viscosity: · Enter pairs of water cut and emulsion viscosity data points in the Emulsion Data table. · Enter the Experimental Parameters · Click the Match button. PROSPER Manual
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When the regression has stopped, click Plot to display the matched mixture viscosity:
Match data is plotted as crosses, whereas the calculated viscosity is shown as a solid line. When Emulsions Everywhere have been selected, the calculated Oil Viscosity in the PVT section will be replaced by the emulsion viscosity for the value of Water Cut entered.
2.4.2.11Non-Newtonian Fluid PROSPER can model the effect of non-Newtonian fluids. The implementation of the model is based on drilling fluid models developed by TotalFinaElf. A fluid whose viscosity is not constant at all shear rates and does not behave like a Newtonian fluid would fall into this category. This will enable foams in heavy oils to be modelled more accurately. Most drilling fluids are non-Newtonian.
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To enter the required non-Newtonian fluid viscosity data, select Rheological Parameters from the PVT Input Data screen:
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The model is based on the Herschel-Bulkley shear model:
where: τ= Shear Stress τ0 = Yield Stress K = Consistency Index γ = Shear Rate n = Shear Thinning Index For further details about how the viscosity model is used to determine the apparent viscosity, please refer to the Help on-line of PROSPER. 2.4.2.12Power Fluid Data If one of the following Artificial Lift Methods have been selected: HSP (Hydraulic Submersible Pump), Diluent Injection or Jet Pump, then additional details of the power fluid must be supplied to estimate the fluid properties. There are two choices for power fluid type: ·
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·
Other Fluid
If Water is selected, then the only other data required is the salinity of the power fluid. The program will then estimate fluid properties using the normal water PVT model. If Other Fluid is selected, then tables of fluid properties need to be entered that PROSPER will use for interpolation. The program will never extrapolate so please ensure that the table data covers the expected ranges of pressures and temperatures. Click the Properties button and the following screen will be displayed.
Tables of data for up to 10 temperatures may be entered. Please ensure that the tables span the expected range of conditions that will be encountered. Ü
The Generate feature allows to automatically calculate the tables using the PVT model in the main screen. If a PVT model is available for the power fluid, the suggestion is the following: 1. Enter in the PVT main screen the fluid black oil properties 2. Use Generate to create the tables modelling the power fluid
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3. Enter in the main screen the black oil parameters for the produced fluid
2.4.2.13Hydrates Formation table If the Hydrates | Enable Warning option has been selected in the main program Options, then a hydrate pressure – temperature look-up table must be entered. Click the Hydrates button and the following entry screen will be displayed.
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Up to one hundred data points may be entered. Please ensure that the table spans within the expected range of conditions that will be encountered.
2.4.3 Black Oil - Dry And Wet Gas All the condensate drop out is assumed to occur at the separator. Free water production in the tubing is considered. For pressure drop calculations, an equivalent gas rate is used which allows for the condensate by ensuring that a mass balance is observed.
2.4.3.1 Input Data When Dry and Wet Gas is selected as the PVT option, the following Input data screen is displayed:
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The bottom-right part of the screen will only appear when the option Calculate Condensate Water Vapour is selected in the Options | Water Viscosity section. If this option is selected, the effects of condensation of water vapour on the pressure drop calculation in the tubing / pipeline will be taken into account. The calculated moisture contents of natural gases is based on the equations of Bukacek (Equilibrium Moisture Content of Natural Gases, Research Bulletin Vol 8, Institute of Gas Technology, Chicago USA, 1955). The correlation on which these calculations are based is accurate to within five percent. This was developed for dry gases. The presence of heavier hydrocarbons in wet gases and retrograde condensates increases the water content by as much as ten percent at 1000 psia and twenty percent at 10,000 psia. The Bukacek correlation is also graphically referenced in McCain, William D. Jr. The Properties of Petroluem Fluids Figures 16-18 and 16-19 and mathematically illustrated in Lee, John and Wattenbarger, Robert A. Gas Reservoir Engineering Section 1.12. The Dry and Wet Gas model applies to most gas wells. The condensate production is included in the gas stream as an increase in density - the flow remains single-phase gas plus free water if present. The Separator Pressure is used to estimate the GE (Gas Equivalent Rate). The separator temperature is assumed to be the same as the top node temperature. If there is significant hydrocarbon liquid drop out in the tubing, a retrograde condensate model should be used. Note the following: Ü
The Gray VLP correlation has an internal PVT routine that models the effect of liquid dropout in the tubing. This overrides the Dry and Wet gas PVT.
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Produced gas is generally saturated with water at reservoir pressure and temperature. Some water of condensation always drops out at the separator. This water has a minimal effect on calculated bottom hole pressures. The WGR considers free water production at the sandface.
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Gas properties e.g. Gas FVF is calculated directly from the gas Z factor. The Z factor is calculated based on the Dranchuk Purvis Robinson (DPR) which is an EOS obtained from curve fitting the Standing and Katz Z factor charts. The gas gravity is used to obtain the pseudo-critical properties based on Brown’s correlations for Tpc and Ppc. The DPR method is then used to calculate the Z factor from which the gas properties are evaluated. The Gas FVF for instance is calculated using the real gas law. Gas viscosity is calculated from the Lee or Carr correlations.
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Please refer to the PVT Matching Data section. Matching operations are carried out as for oil PVT.
2.4.4 Black Oil - Retrograde Condensate The PROSPER Retrograde condensate (Black Oil) model has been developed in house by Petroleum Experts. This model predicts liquid drop out taking place in the tubing. The reservoir gas gravity is determined using the principle of mass balance for an equivalent density of the oil. Unlike bubble point systems (oil), the black oil condensate model should not be matched against lab or simulated PVT data. This is because the black oil model for condensate in PROSPER uses a mathematical model based upon mass balance and matching could throw the model out of bounds. The equations used are given in Appendix B. 2.4.4.1 Input Data When Retrograde Condensate (Black oil) PVT is selected the following input data screen is displayed:
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Enter the required data. Note: If tank GOR and tank gas gravity is unknown, they can be left at 0. The unmeasured tank gas rate should be estimated using a suitable correlation and added to the separator gas. For such cases, the total produced GOR should be entered under separator GOR. Condensate gravity is at standard conditions. Ü
If the separator pressure is above dew point, then there can be no liquid production. When the dew point is unknown, set it to the reservoir pressure. PROSPER handles conflicting input data by dropping the separator pressure to atmospheric, and increasing the separator gas gravity as required accounting for the liquid production indicated by the Separator GOR. The mass balance is respected at all times.
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The black oil condensate model must not be matched as previously done for oils. This is because the black oil model for condensate in PROSPER uses a mathematical model and matching could throw the model out of bounds.
2.4.4.2 Calculations Fluid property data can be calculated for a specified range of temperatures and pressures. If the correlations have been matched, then the matched correlations will be used for the calculations. Plots of fluid properties versus temperature or pressure can © 1990-2011 Petroleum Experts Limited
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be generated. Ü
The calculated PVT property values should be compared to constant composition expansion (CCE) data, as this process best describes the evolution of the fluid in the tubing.
2.4.5 Export NEW!!! The Export button enables the user to export input data, correlation parameters, Match Data, Tables and Calculation results from the PVT main section.
2.4.6 Equation Of State - All Fluids This PVT option allows PROSPER to calculate the vapour fraction and fluid physical properties using an equation of state (EOS) description for the reservoir fluid. Peng-Robinson and Soave Redlich Kwong EOS models are available in PROSPER, also User EOS PVT modules can also be linked to PROSPER. The PVT calculation method is identical for all reservoir fluid types (i.e. oil and water, condensate or gas). The fluid type selected will affect the choice of IPR and VLP models as well as the range of available sensitivity variables. Equations of State were developed to give a mathematical relationship between pressure, volume and temperature. They were originally put forward as a method of interpreting the non-ideal nature of many pure substances. With time, this role has been extended successfully to predicting the properties of simple and complex mixtures. PROSPER Manual
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The equations used in PROSPER are derived from Van der Waals Equation and in common with it represent the total pressure as a summation of an attractive and a repulsive element: P total = P repulsive - P attractive The classic Van der Waals equation describes this relationship as
where ‘b’ represents the hard-sphere volume of the molecules and ‘a’ the intermolecular attraction. The two cubic Equations of State which are available in PROSPER are: 1) Peng-Robinson (PR)EoS:
and, 2) Soave-Redlich-Kwong(SRK)EoS:
All cubic Equations of State can be rewritten as a function of the compressibility factor Z e.g. the Peng Robinson equation becomes:
and for SRK where
and
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The PVT calculation method is identical for all reservoir fluid types i.e., oil and water, condensate or gas. The choice of fluid type affects the choice of IPR and VLP models as well as the range of available sensitivity variables. A Note about using the EOS option PROSPER can handle pressure drop calculations using EOS PVT in two distinct ways: ·
It can calculate fluid properties at each calculation step from the EOS explicitly. This option eliminates any potential interpolation errors, as the EOS is used to calculate fluid properties at the exact node pressure and temperature. The additional computing overhead required by this method increases calculation times.
·
If PVT tables have been generated using the EoS, selecting the Interpolated from Generated Tables option instructs PROSPER to look up and interpolate the tables. The tables must be calculated over a sufficient number of points that cover the entire range of pressures and temperatures to reduce interpolation errors. For problems that require it, the Use Tables option allows an EOS fluid description to be used without significantly increasing computation times.
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PROSPER will determine whether the reservoir fluid is an oil or a gas condensate within the EOS PVT calculations. Since the VLP correlations are approached differently depending on whether a gas or oil is being produced, when running calculations, if the fluid type recognised during the calculations is different to the fluid type specified in the main program Options screen, the program will display a warning message
2.4.6.1 EOS Model Setup The EOS fluid mode options must be consistent with the entered compositional data for PROSPER to calculate.
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The EoS options can now be set up by selecting EoS Setup:
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The following main EOS options can be pre-set: EoS Model Select one of the available EoS equations: Peng-Robinson or Soave-RedlichKwong. Optimisation Mode PROSPER Manual
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Over the past few years, our PVT experts have been working on ways to speed up the calculation of properties from an EOS model. Speed is one of the main issues with fully compositional models and the options in this field will define the speed of calculations. The objective of this option is to speed up the calculations without penalising the accuracy the results. The Medium mode is the fastest (up to 80 times) Volume Shift Option to enable/disable the use of Volume Shift in the EoS.
Path to Surface This Option specifies the path the fluid follows down to standard condition. This is essential when calculating volumetric properties like FVF or GOR, which are path dependent. The amount of gas and liquid resulting from the calculations will be different depending on the path the fluid will take to standard conditions. These are the available options: ·
Flash Straight to Stock Tank
·
Use Separator Train
·
Use K values The “Use K Values” option is an addition to the compositional modelling that allows modelling the process based on K-values (equilibrium ratios). This can allow process calculations from systems more complex than separation to be represented as “Pseudo” separators and can be obtained from process simulators. To import the K values select Import KValues:
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K-values can be entered by hand or also generated in PVTp by performing a simple separator experiment, and then exported to PROSPER.
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These options should reflect the EOS available for the fluid (from PVTP for example) and the process (path) the fluid follows to standard conditions (which will affect the volumes and quality of the resulting fluid)
Target GOR Method A single composition will only provide a single value of GOR through a defined separator train. There are applications when other GOR values are required e.g. in the production of lift curves. This calculation takes the gas and oil derived from the fluid and recombines them until it reaches the target value. There are two methods available to the user. The difference between them lies in the source of the gas and liquid to be mixed. · Use Separator fluids uses the dead oil and accumulated separator gas to create the mixture · Use fluid from PSAT finds the saturation pressure of the fluid. The program then flashes just below PSAT to obtain an oil and gas composition. These are mixed to achieve the target GOR. It should be noted that this retricts any target that can be found to the RS of the oil below PSAT and the GOR of the equivalent gas. Although more restricted, this mixture better reflects the case of an oil entraining gas cap gas etc.
2.4.6.2 EOS PVT Input Data A sample EOS PVT input screen is shown below:
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The EOS fluid model is activated via the Options Summary screen where the various EOS options can be selected. The Options can also be changed from the EoS main screen by selecting Change. This screen requires input of pseudo component concentrations and properties (critical temperature, pressure and volume, acentric factor, molecular weight and specific gravity). Up to 30 pseudo components can be entered. Entry of Critical Volume, Volume Shift, Boiling Point Temperature and Parachor are optional. Use of regressed critical volume data will improve the quality of calculated liquid viscosities. Where critical volume data is unavailable, PROSPER uses a correlation to estimate the values. The Parachor is used for surface tension calculation. Binary interaction components are entered on a screen similar to that shown below by clicking on the BI coeffs button from the EOS input screen.
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After entering the interaction coefficients, click OK to return to the input screen. Then click Generate to display a screen requesting the range of pressures and temperatures and the number of pressure and temperature steps to calculate.
2.4.6.2.1 Importing Matched EoS The EoS model can also be imported by using the Import…PRP feature. The .PRP file contains all the information necessary to the EoS: EoS parameters, BI Coefficients, Options, Separator train, etc., and can be generated using Petroleum Experts' PVTP.
2.4.6.3 Using the EoS
2.4.6.3.1 Generate PVT properties The fluid properties can be generated using the EoS in different ways: ·
Calculated directly from the EoS
·
Interpolate the properties from Tables generated by the EoS itself
The first option is the most accurate, though the slowest. Choose the desired option from the menu available in the left bottom of the EoS window. Performing CCE calculations Calculate the PVT fluid properties using the EOS directly by clicking Generate.
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Enter the range of temperatures and pressures and Calculate | Calculate.
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Display the results by clicking Plot
Properties Click the Properties button and the program will determine the equivalent black oil properties by flashing the fluid to atmospheric (i.e. standard) conditions using the
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separator scheme entered in the main screen.
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Production rates entered in PROSPER when using EOS PVT assume the produced fluid is flashed through the user-entered separator train.
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The EOS option in PROSPER is not intended to be used as a fully featured PVT package. For the initial compositional calibration of the fluid, it is recommended to use a specialized program such as Petroleum Experts’ PVTP.
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The Gray VLP correlation’s internal PVT will override the EOS PVT.
2.4.6.3.2 Phase Envelope Generating the Phase Envelope The phase envelope can be displayed by selecting the Phase Envelope button. In this section the Phase Envelope can be calculated:
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The Plot button displays the calculated Envelope:
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The EOS input screen allows pseudo component data to be imported directly from data files such as those generated by Petroleum Experts' PVT package PVTp or other programs. Simply click Import and select the appropriate file from the dialogue box. Once fluid properties have been generated, they can be saved in a .PVT file by clicking the Save button and entering a file name when prompted. Calculate Hydrate...Wax This utility allows to calculate the Hydrate formation curve, along with the wax occurrence temperature. The Hydrate formation curve and wax formation temperature plot will be displayed along with the phase envelope. 2.4.6.3.3 Target GOR This feature allows to calculate the recombined fluid composition characterised by a GOR different to the Original Composition GOR:
Enter the new GOR in the Target GOR field and then Calculate, and the program will use the Target GOR method defined in the main EoS options in order to determine the new composition. The Calculated composition is reported in the Calculated column.
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Equipment Data Input This section describes the menu option used to define the well's hardware, deviation survey and flowing temperature profile. The program requests only the data required by the Options that have been selected. The data required for temperature prediction depends on the temperature model used. For the Rough Approximation and Improved Approximation, there is little additional data required. For the rigorous Enthalpy Balance temperature model, it is necessary to completely define the well environment, including all casing strings, cement tops, formation lithology etc. A Note about Depth References. Ü
Depths in PROSPER for downhole and surface equipment are referenced to zero on the deviation survey screen. Calculated pressures are then referenced to the Xmas tree (if no surface equipment has been entered) or Manifold (if surface equipment has been entered). Therefore, when PROSPER well models are combined in a field-wide system model, the depth references that were used in the individual PROSPER models are not important. In the field model, however, the depth of each well's Top Node must be known with respect to a common reference.
Ü For subsea systems, any depth reference (e.g. sea level, drill floor, ground level) can be used. If ground level is used, then a tied back well would have a negative wellhead elevation. To minimise the potential for errors in correcting the depths, it is recommended to use the same reference as used for the deviation survey data.
2.5.1 Predicting Pressure Only When predicting Pressure only, click System¦ Equipment to display the following input screen:
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To start data entry for a new application, click All¦ Edit. PROSPER will then display all the relevant input screens in sequence. If data has already been entered, clicking the Summary command button will display a summary of the current equipment. To go back and edit one particular equipment item, click on the button beside the appropriate item. Data can be entered for the surface equipment and then include or exclude it temporarily from any calculation by setting the Disable Surface Equipment choice box at the bottom of the screen to Yes.
2.5.1.1 Deviation Survey From the well deviation survey, select a few depth points that mark significant changes in deviation. Enter pairs of data points for measured depth (MD) and the corresponding true vertical depth (TVD). Up to 18 pairs of data points can be entered. The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources.
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Ü There is a Measured Depth to True Vertical Depth (and the reverse is true) at the bottom. © 1990-2011 Petroleum Experts Limited
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If the user wishes to find the TVD at a given MD, just enter the MD value in the relevant space and select Calculate. If the User wishes to find the MD at a given TVD, just enter the TVD value in the relevant space and select Calculate Once depths have been entered, plot the well profile by selecting Plot. A plot similar to the one below will be displayed:
Ü
The reference depth used by PROSPER for all calculations is zero in the Deviation Survey table. The Deviation Survey table is interpolated to determine the difference in TVD between any two well nodes. MD and TVD data must be at least as deep as the bottomhole tubing depth; PROSPER will not calculate beyond the last depth in the table.
Ü
Deviation Survey data entry is required also for vertical wells - enter 0,0 for the surface reference and an MD the same as the TVD of the intake node. The deviation survey has to start with 0 measured depth and 0 TVD. Due to this reason, the reference depth (where TVD = 0) has to be at or above the wellhead.
Ü
For a sub-sea well (with or without pipeline), if the reference depth is selected in such a way that it is above the wellhead (at the mean sea level for instance), we can actually assume an imaginary vertical path in the deviation survey table down to the wellhead. We do not need to include the pipeline measured depth in the deviation survey. The deviation survey describes the deviation of the downhole equipment only.
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Ü
Horizontal wells with deviation angles greater than 90 degrees from vertical can be entered. PROSPER will issue a warning that the TVD of one node is less than the previous one, but well profile plots and calculations will proceed as normal.
Ü
For Horizontal wells the deviation survey may be entered only up to the heel of the well, as the well from the heel all the way up to the to is a part of the inflow description.
2.5.1.1.1 Filter When more than 18 points are available, the Filter allows a determined number of points (up to 18) that best-fit the entered points (see figure below).
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In the Raw Data table (figure above) enter the data from the survey. Ü It is possible to copy the table by selecting the first row (click on the number 1) and Paste from the Clipboard These are the function buttons: Calculate Calculates the angle of deviation from the vertical Angle Reset PROSPER Manual
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Filter
Calculates a number of points which fit the deviation table entered on the left. Check the fitting by hitting on Plot. If this is not ok, change some parameters (like for example the angle step)
Transfer
Transfers the calculated points to the main Deviation Survey screen
The Filter parameters are described in the following table: Used to chose second point of the deviation survey; the point Initial Filter Angle with higher angle will be filtered through Angle Step
Defines the minimum angle difference between two points; if the difference is higher the point will be filtered through
Maximum Number of Points
The Maximum Number of Points that can be filtered through; if the number of points filtered is more than the value specified PROSPER will increase the angle to satisfy the criterion
Actual Filter Angle
The angle calculated by PROSPER to satisfy Maximum Number of Points criteria
When selecting Filter, the program will filter the points in order to reproduce the well trajectory previously imported. The first point of the deviation survey is always filtered through as a starting point. Then the Initial Filter Angle parameter is used to choose second point of the deviation survey; i.e. the first point along the deviation survey where the angle from the vertical goes above the initial filter angle will pass through the filter and is selected as the second point. The next points are filtered through based on the Angle Step; i.e. if the difference in the angle between two points is more than the value specified. PROPSER actually calculates the Angle Step internally depending on the Maximum Number of Points entered by user; i.e. if the number of point passed through the filter is more than the Maximum Number of Points specified the angle will be increased to satisfy the former. The resulting value is then reported as Actual Filter Angle. Ü The filtering is performed on the basis of Measured Depth (not Cumulative Displacement). In essence, the filtering ensures that the measured depth (and TVD) between two points is always consistent with the original survey even though plotted profiles may appear slightly different. This is because Measured Depth defines length of the pipe (tubing), which is particularly important in temperature and pressure drop calculations in PROSPER.
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The Plot function allows to quality check the fitting. In the plot the well entered trajectory (in red) is plotted along with the fitted points (in green):
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2.5.1.2 Surface Equipment The Surface Equipment screen is used to enter surface flowline, choke and pipe fitting data as shown below:
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Fittings have been added to the surface equipment section of PROSPER to account for the various pressure losses associated with pipe fittings throughout a given system:
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PROSPER defines surface equipment as the pipe work between the production manifold and the upstream side of the wellhead choke. The production manifold is regarded by PROSPER as presenting a constant back-pressure, regardless of flow rate. If systems analysis is to be performed relative to the wellhead, (i.e. gathering system pressure losses are neglected) then no surface equipment input is required. The surface equipment model can be described using the following 2 elements: · Pipe · Choke The manifold is set as the first equipment type automatically by PROSPER. Surface equipment geometry can be entered either as pairs of X, Y co-ordinates relative to the manifold or the Xmas Tree, Reverse X, Y (Y co-ordinates deeper than the reference depth are negative) or TVD of the upstream end and the length of the pipe segment. The difference in TVD between the ends of a pipe segment is used to calculate gravity head losses. The internal diameter (ID), roughness and pipe length entered determine the friction pressure loss. The flowing temperatures for each upstream node must also be entered when calculation option Pressure only is selected. The Rate Multiplier column enables simulation of the pressure drop due to several identical wells being connected to a production manifold via a common surface flow line. The fluid velocity in the flowline is multiplied by the value entered increasing the frictional pressure losses. For most applications it should be left at its default value of 1. © 1990-2011 Petroleum Experts Limited
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Ü
As an example, the pressure drop in a flowline connected to 3 identical wells could be modelled using a pipeline rate multiplier of 3. 2 parallel flowlines having identical dimensions can be modelled by entering the actual dimensions for one pipe and a pipeline rate multiplier of 0.5. It is also possible to vary the rate multiplier along the pipeline to simulate varying sections of dual pipelines for example.
The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources. Up to 200 pipe segments can be entered, enabling the user to model very long pipelines.
PROSPER multi-phase choke pressure loss correlation accounts for both critical and sub-critical flow. We would recommend the use of the ELF Choke correlation that it similar to the Petroleum Experts’ method and is more robust in extreme conditions. Ü
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Ensure that the length of each pipe segment is equal to or greater than the difference in TVD between its ends.
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The downhole and surface equipment entries must describe a continuous system. The TVD and temperature of the upstream end of the last pipeline segment should be equal to the Xmas tree TVD and temperature. In X,Y coordinates, the Y co-ordinate of the last pipe segment must be the same elevation as the wellhead TVD. (i.e. same magnitude, but opposite sign) To check that the surface equipment description is accurate, click Plot to display a plot of the pipe elevation as follows:
2.5.1.3 Downhole Equipment The Downhole Equipment screen enables the downhole tubing string data to be entered.
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The Downhole Equipment screen will change automatically depending on the options selected in the Options menu screen. For example, if Annular Flow has been selected, the tubing screen will require Casing I.D. and Tubing O.D. to be entered. The tubing string can be modelled using the following element types: · · · ·
Tubing SSSV Restriction Casing
PROSPER automatically inserts the Xmas tree as the first downhole equipment item. To describe the tubing string, work from the shallowest depth downwards, entering the bottom depth of changes in tubing diameter, ID and roughness factor. Ü
An SSSV is considered to have no length, and is modelled as a sharp-edged orifice inserted between adjacent tubing string elements. A restriction is handled identically to an SSSV. The pressure loss calculations in PROSPER account for choking as sonic flow velocity is approached.
Casing is treated the same as tubing for pressure drop calculations. Downhole equipment details should be entered down to the producing interval being analysed. PROSPER Manual
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The deepest depth entries for the tubing, deviation survey and temperature should be consistent. Ü
Below the uppermost producing perforation, the flow profile (as measured by a production logging tool) depends on layer productivity etc. The uppermost producing perforation is the deepest point in the well passing 100% of the production. Below this point, the calculated frictional pressure gradient may be over-estimated in high rate wells having small I.D. completions.
To select tubing string elements to build up the tubing string description, click on the list box arrows to the right of the item fields and select the equipment from the drop-down list. The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources. Up to 18 tubing string elements can be input. For complex completions, simplify the data entry by entering only the major elements that dominate the overall tubing pressure drop. The Rate Multiplier column enables simulation of the pressure drop due to intermittent sections of dual completion. The fluid velocity in the tubing is multiplied by the value entered - thereby increasing the frictional pressure losses. For standard single tubing completions it should be left at its default value of 1. 2.5.1.4 Temperature Survey This screen enables entry of the flowing temperature profile of the well. If no bottom hole flowing pressure survey data is available, the static reservoir temperature at the mid-point of perforations and the wellhead flowing temperature can be used. A minimum of two depth / temperature points is required.
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The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources. Ü
PROSPER interpolates temperatures from the survey data for depths within the table limits, and uses linear extrapolation elsewhere. To eliminate potential errors, ensure that a temperature is entered for the deepest node depth. It is recommended that the maximum temperature survey depth, deviation survey depth and intake node depths are all consistent.
2.5.1.5 Pipe Schedule and Equipment In the Surface Equipment or in the Downhole Equipment section it is possible to import as pipe, tubing and casing ID values from databases containing pipeline, tubing and casing data. In the Surface Equipment section this is achieved by selecting the Pipe Schedule button: PROSPER Manual
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In the Surface Equipment section this is achieved by selecting the Equipment button:
These are the steps to import the equipment ID: 1. Select the Type of equipment from the screen - for example, Tubing - as shown below:
2. Select the row corresponding to the piece of equipment and select the Equipment button (if in the Surface Equipment section, select Pipe Schedule) and select the database (in this case Tubing Database) 3. Select the equipment to use from the database
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Then Copy and Done 4. The program will show a dialog with at the bottom an option on the way forward.
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For example, selecting Copy ID and OD to Selected Records, then Done will pass the values to the equipment screen:
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2.5.2 Predicting Pressure and Temperature The Equipment data entry screens vary depending on the Temperature model selected in the main program Options. 2.5.2.1 Rough Approximation Equipment entry for the Rough Approximation temperature model varies little from the Predicting Pressure Only option. Click on System½Equipment to display the following input screen:
To start data entry for a new application, click All ½ Edit. PROSPER will then display all the relevant input screens in sequence. If data has already been entered, clicking the S ummary command button will display a schematic summary of the current equipment. To go back and edit one particular equipment item, click on the button beside the appropriate item. Data can be entered for the surface equipment and then include or exclude it temporarily from any calculation by using the Disable Surface Equipment choice box at the bottom of the screen. PROSPER Manual
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2.5.2.1.1 Deviation Survey Enter data as per Pressure Only case.
2.5.2.1.2 Surface Equipment Surface Equipment is the same as for Predicting Pressure Only except for the requirement to enter the temperature of the pipe surroundings and an overall heat transfer coefficient.
The heat transfer coefficient should not be confused with the pipe thermal conductivity. The overall heat transfer coefficient accounts for the heat flow through the production tubing, annulus and insulation (if present) to the surroundings. Heat transfer by forced and free convection, conduction and radiation must all be accounted for in the value of the overall heat transfer coefficient. In PROSPER, the overall heat transfer coefficient is referenced to the pipe inside diameter.
2.5.2.1.3 Downhole Equipment The Downhole Equipment is the same as for Predicting Pressure Only. The casing between the producing perforations and the tubing shoe is considered to be part of the Downhole Equipment for the Rough Approximation temperature option. Therefore the casing details should be entered in the Downhole Equipment. Please refer to Predicting Pressure Only section for more details. © 1990-2011 Petroleum Experts Limited
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2.5.2.1.4 Geothermal Gradient This is where the Rough Approximation temperature model differs most from the Pressure Only case. PROSPER requires the formation temperature profile to be entered on this screen:
Ü
Enter static formation temperatures from e.g. extrapolation of temperatures recorded on logging runs - NOT flowing well bore temperatures.
As for surface equipment, enter an overall heat transfer coefficient that describes the resistance to heat flow by all mechanisms (convection, radiation and conduction) from the well to its surroundings. The Enthalpy Balance temperature model is a convenient way to determine average heat transfer coefficients. The heat transfer area is referenced to the pipe inside diameter. 2.5.2.1.5 Average Heat Capacities To edit Average Heat Capacities, click its check box then click Edit to display the following dialogue: PROSPER Manual
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Enter values that correspond to average conditions in the well. Note that for oil, and especially gas that Cp values are strong functions of both temperature and pressure. Ü
The default values will often give reasonable results in moderate GOR oil wells. However, actual Cp values for oil and gas may vary significantly. Do not rely on the defaults - obtain good estimates of Cp, or use the Enthalpy Balance method where accurate temperature prediction are achieved.
2.5.2.2 Enthalpy Balance To commence data entry for a new application, click All / Edit. PROSPER will then display all the input screens in sequence. If data has already been entered, clicking the Summary command button will display a summary of the current equipment. To go back and edit one particular equipment item, click the button on the left of the appropriate item.
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2.5.2.2.1 Deviation Survey Enter data as per Pressure Only case.
2.5.2.2.2 Surface Equipment An example of the surface equipment screen is shown below:
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To calculate heat losses, additional data such as outside diameter, material type and insulation (if used) are required to be input. The surface equipment model can utilise the following equipment types: · · · · ·
Line pipe Coated pipeline Flexible tubes User selected Choke
To allow for pipe bends, etc., enter an equivalent length/diameter. The choke calculation handles both sub-critical and critical flow. The program will calculate the temperature drop across the choke. Descriptive labels for each element can be entered in the Label field if desired. Labels appear on reports and calculation screens. Surface equipment geometry can be optionally entered as TVD of the upstream end of the pipe segment and length or as X, Y (from the manifold or the Xmas Tree) coordinate pairs. Refer to Section 6.1.2 above for more details. The Rate Multiplier column enables simulation of the pressure drop due to several wells being connected to a production manifold via a common surface flow line. The fluid velocity in the flowline is multiplied by the value entered - thereby increasing the frictional pressure losses. For most applications it should be left at its default value of 1. As an example, the pressure drop in a flowline connected to 3 identical wells could be modelled using a pipeline rate multiplier of 3. 2 parallel flowlines having identical dimensions can be modelled by entering the actual dimensions for one pipe and a © 1990-2011 Petroleum Experts Limited
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pipeline rate multiplier of 0.5. It is also possible to vary the rate multiplier along the pipeline to simulate varying sections of dual pipelines for example. The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources. Up to 200 pipe segments can be entered, enabling the user to model very long pipelines. Pipe insulation (e.g. concrete, foam or bitumen) can be modelled. To define the pipe insulation click the Enter button to display the following screen:
Select the required insulation type from the drop-down list, then enter the thickness. Enter the insulation beginning with the innermost layer. PROSPER uses the thermal properties in its database to calculate the thermal conductivity of the composite insulation. Click OK to return to the surface equipment screen. Different insulations can be entered for each section of the flowline as required. The calculated composite thermal conductivity is referenced to the pipe inside diameter. Pipes can be laid on the surface (burial depth = 0) or buried. The diagram below shows the burial depth geometry. PROSPER Manual
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The burial depth is the distance between the soil surface and the bottom of the pipe (including insulation, if present). The pipe is partially buried if the burial depth < O.D. of the insulated pipe.
Ü
Ensure that the flowline pipe geometry is consistent with the pipe burial depth. If necessary, insert another node and change the burial depth for e.g. the riser.
Ü
The soil conductivity around buried surface pipes is taken from the Thermal Properties database for the shallowest rock type entered in the Litho logy screen. In previous PROSPER releases, the soil conductivity was fixed at 3.5 W/m/K.
2.5.2.2.3 Downhole Equipment The downhole equipment section is used to describe the production tubing, SSSV and restrictions. The following equipment items are available: · · · · ·
Mild steel tubing Plastic coated tubing Stainless steel (either 13% or 25% chromium) SSSV Restrictions
The thermal properties database for downhole equipment elements can be edited or added to if required. Pressure and temperature changes across subsurface safety valves and restrictions (nipples) are correctly modelled. The following is an example of a downhole equipment data input screen: © 1990-2011 Petroleum Experts Limited
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For the Enthalpy Balance temperature model the casing dimensions and material type are entered under Drilling and Completion, so the downhole equipment description is required only for the tubing string. To select tubing string elements to build up the tubing string description, click on the list box arrows to the right of the item fields and make the appropriate selection from the drop-down list. The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources. Up to 18 tubing string elements can be input. For complex completions, simplify the data entry by entering only the major elements that dominate the overall tubing pressure drop. The Rate Multiplier column enables simulation of the pressure drop due to intermittent sections of dual completions. The fluid velocity in the tubing is multiplied by the value entered - thereby increasing the frictional pressure losses. For standard single tubing completions it should be left at its default value of 1.
2.5.2.2.4 Temperature Data The Temperature Data section is required for the calculations of heat loss for surface flow lines and wellbore. Data must be entered according to the screen shown below depending on whether prediction is being done offshore or on land. PROSPER Manual
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in the Temperature Data screen enter the temperature gradient in the formation (just like in the Geothermal Gradient section for Rough Approximation), and the temperature profile in the sea, along with the sea velocity. If the surface equipment is exposed to air, the data concerning to the air temperature, humidity and velocity will be accounted for the temperature calculation
2.5.2.2.5 Drilling and Completion This data is used to calculate the heat transfer coefficients down hole. If the offshore option has been selected, the marine riser parameters must be entered in this section. © 1990-2011 Petroleum Experts Limited
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Entries must be from TOP to BOTTOM. Thus, the riser will be the first entry. The screen below shows an offshore well with a 30" OD riser run to a seabed depth of 400 ft. The well also has a 7" OD liner run to 14000 ft with the liner top set at 11000 ft.
The completion fluid Liquid and Gas properties can have a significant effect on the heat loss through the annulus. If pressure is maintained on the annulus, the mud weight used should be modified to reflect the actual annulus pressure at the packer depth. If the well is being gas lifted, the program assumes that the annulus is full of gas down to the injection point. The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources. Ü
Ensure the Tubing OD is less than the Casing ID.
For complex completions fluids, select the appropriate Customised Options from the main Drilling and Completions section. Completion fluid property data will be entered via look-up table data. The figure below shows the data required when selecting the Completion Fluid Gas Type | Customised option from the drilling and completions section.
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Five temperature dependent tables of properties can be entered. Please ensure that the table will span the expected range of pressure- temperature conditions. The program will not extrapolate outside the range of the input table. Use the Import button to import data from a wide variety of sources.
2.5.2.2.6 Lithology The program contains a database of thermal properties for various rock types including Sandstone, Shale, Limestone, Dolomite, Halite and others. The thermal properties database can be edited and added to as required. If detailed lithology data is available it should be entered in the screen as shown below. If no data is available, use shale from surface to total depth.
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The reservoir temperature and pressure should be entered for the production reference depth. The formation temperature gradient is interpolated between the reservoir and surface environment temperatures. The editing buttons Cut, Copy, Paste, Insert and Delete operate on data records that have been selected by clicking on their row number button(s). All records can be simultaneously selected by clicking the All button. Use the Import button to import data from a wide variety of sources. Ü
Thermal properties for buried pipelines are taken from the shallowest formation type entered in the Lithology screen.
2.5.2.2.7 Databases This optional feature is used to access the thermal properties databases for editing or addition of user-defined materials. Select Databases and click Edit and the following selection screen will be displayed:
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Enter appropriate values for the Conductivity of cement and casing. Depending on the selection, PROSPER expects input of thermal conductivity, emissivity, specific heat capacity, specific gravity or density. An example of the Insulation Types database screen is shown below:
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Ü
Check that the units are correct prior to entering the thermal properties.
Edited values remain in memory and become part of a particular well model file when the file is saved. To permanently save edited values or new user-defined entries for use in other projects click the Save button to keep them in the database. The Reset button is used to return all entries to their default values.
2.5.2.3 Improved Approximation Equipment entry for the Improved Approximation temperature model varies little from the Rough Approximation option. Click on System Equipment to display the following input screen:
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To start data entry for a new application, click All Edit. PROSPER will then display all the relevant input screens in sequence. If data has already been entered, clicking the S ummary command button will display a summary of the current equipment. To go back and edit one particular equipment item, click on the button beside the appropriate item. Data can be entered for the surface equipment and then include or exclude it temporarily from any calculation by using the Disable Surface Equipment choice box at the bottom of the Equipment Data screen.
2.5.2.3.1 Deviation Survey Enter data as per Pressure Only case.
2.5.2.3.2 Surface Equipment Surface Equipment is the same as for Predicting Pressure Only except for the requirement to enter the overall heat transfer coefficient an the surrounding temperature.
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The heat transfer coefficient can be specified for each pipe segment and should not be confused with the pipe thermal conductivity. The heat transfer coefficient accounts for the heat flow through the production tubing, annulus and insulation (if present) to the surroundings. Heat transfer by forced and free convection, conduction and radiation must all be accounted for in the value of the overall heat transfer coefficient. In PROSPER, the overall heat transfer coefficient is referenced to the pipe inside diameter. 2.5.2.3.3 Downhole Equipment The Downhole Equipment is the same as for Predicting Pressure Only. 2.5.2.3.4 Temperature Data PROSPER requires the formation temperature profile together with the heat transfer coefficient to be entered on this screen:
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Enter static formation temperatures from e.g. extrapolation of temperatures recorded on logging runs - NOT flowing well bore temperatures.
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coefficients. The heat transfer area is referenced to the pipe inside diameter.
2.6
IPR Data Input This section describes how PROSPER defines the reservoir inflow performance. The following table lists the Inflow Performance options: IPR Method
Oil & Water
Dry & Wet Gas
Retrograde Condensate
Back Pressure
ü
ü
C and n
ü
ü
Composite
ü
Darcy
ü
Dual Porosity
ü
ü
ü
External Entry
ü
ü
ü
Fetkovich
ü
Forchheimer
ü
ü
Forchheimer with Pseudo - Pressure
ü
ü
Multirate Forchheimer with Pseudo Pressure
ü
ü
ü
ü
Horizontal well - No Flow Boundaries
ü
Horizontal well - Constant Pressure upper boundary
ü
Horizontal well - dP friction
ü
ü
ü
Horizontal well - transverse vertical fractures
ü
ü
ü
Hydraulically fractured
ü
ü
ü
Jones
ü
ü
ü
Multi-lateral
ü
ü
ü
Multi-layer
ü
ü
ü
Multi-layer - dP Loss
ü
ü
ü
ü
ü
ü
ü
Multi-rate C and n Multi-rate Fetkovich
ü
Multi-rate Jones
ü
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Modified Isochronal IPR
ü
ü
Petroleum Experts
ü
ü
ü
ü
ü
ü
P.I. Entry
ü
SkinAide
ü
Thermally Induced Fracture (injection only)
ü
Transient
ü
Vogel
ü
SPOT
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2.6.1 IPR Single Well Data The data for inflow performance models is entered using a single master screen. All the sub-screens relevant to a set of model choices are accessible through clicking on buttons on the main screen and on a tabbed interface in a data input screen. This means that data for different models are entered concurrently and can be compared before selecting the Calculate option. The generic features of the single well data entry screen are used in the multilateral interface for data entry to those network items with sufficiently large data structures (namely tubing, completion and reservoir). Click System Inflow Performance in the main menu and the main data entry screen will appear. 2.6.1.1 The Main Data Entry Screen The screen consists of three parts. 1. Section Buttons. At the top right of the dialog screen are two buttons, labelled Select Model and Input Data. These allow switching between screens that control model selection and detailed data input. The former also contains data pertaining to all models (such as reservoir pressure and temperature), and the latter manages the data input specific to the chosen model. The selection buttons have the same function in the multilateral data entry screens. 2. Action Buttons. To the left of the section buttons is a set of buttons that perform various actions such as Calculate. Only the left-most group appears in the multilateral data entry screens. 3. Model Selection Screen. The child screen is the area below the action and section buttons and contains either the model selection or the data input screens. The same occurs in the multilateral interface, although the actual model selection and data input screens are different. © 1990-2011 Petroleum Experts Limited
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2.6.1.2 Section Buttons As well as switching between the model selection and data input screens the section buttons also indicate the validation status of the screens. The selection of one screen or the other is shown by the indentation of the button for that screen and the validity of the data is flagged by the colour. Green means that all the required data are entered and within the numerical range for the units chosen; where appropriate, extra consistency checks have also been carried out. Red implies that either there is insufficient data entered or it is out of range/inconsistent. In addition, if no models at all are selected the Select Model and Input Data buttons are marked invalid. Also, if not enough models are selected the Select Model button is marked invalid (e.g. a reservoir but no skin model). 2.6.1.3 Action Buttons
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This button exits the screen after saving and validating all the data pertaining to the chosen models. If the data are not valid an option of remaining in the IPR edit screen and reviewing the validation errors that are listed in a validation error dialog is provided. This also occurs after the validation in the Calculate, Transfer Data and Save Results button May, 2011
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commands. If the IPR section is exited with invalid data left in the input then all calculation options using IPR data and models are disabled. Cancel This exits the screen and restores the data to its state at the start of the main edit session Validate Checks the data on the current child screen for validity. If the data are not valid, the validation dialog will appear with diagnostic messages Reset This replaces the data of the current child screen with the data that was current when the screen was entered Help This displays information relevant to the current child screen Calculate Saves and validates all the data pertaining to the chosen models (e.g. Darcy reservoir model and Enter Skin By Hand) then runs the correct calculation routine if the data are valid. On successful completion of the calculation the results are automatically plotted Plot Will produce a plot screen appropriate to the current reservoir model (for example, a Darcy plot) and plot the data from the last Calculate command Report Enters the PROSPER Reporting System. The report produced will depend on the current model choices Export Can export current data (input and results) to the printer, a file, the clipboard or the screen Test Data Allows to enter the test data (rate vs Bottom Hole Pressure, a date stamp and a comment) that will be then displayed in the IPR plot Sensitivity Allows to perform sensitivities on the various parameters affecting the IPR Transfer Data
Save Results GAP
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Saves and validates all the current data before opening a standard ‘File Save As’ dialog that provides an opportunity to save the data to file in MBAL input format (.MIP). If PROSPER has been opened from a session in GAP then the data are posted to GAP instead. The transfer button does not prompt for creation of a .MIP file. This option is only enabled when PROSPER is run from GAP. On a successful validation options to either over-write the current file or to save the PROSPER file using ‘File Save As’ options are provided This option is only enabled when PROSPER is run from GAP. It shuts down the IPR screen and minimises PROSPER, thus bringing GAP to the forefront
Note that the ‘Save and Validate’ sequence carried out by several of the action button commands does not actually save to file but transfers data from the context of the IPR data screen to the PROSPER data structure in memory. Hence, files should regularly be saved to avoid losing work due to power failures or crashes.
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2.6.1.4 Model Selection Screen An example of the model selection screen for the ‘Oil and Water’ fluid choice can be seen in the screen dump of the main data screen. This part of the IPR input screen controls the choice of almost all the tabbed dialogs that will be seen in the subsequent data input screen. There are four major selections done in this screen. These are: ·
Selection of Reservoir Inflow Model For each fluid various single well IPR models available are listed and the User makes a selection.
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Selection of mechanical/geometrical skin The User has the option of entering the skin by hand or using one of the analytical models to model the completion skin.
·
Selection of deviation / partial penetration skin There are two skin models and these become available if a analytical skin model of mechanical / geometric skin calculation has been used.
·
Reservoir input The User also specifies the pressure, temperature, producing GOR and water cut at this screen.
·
Relative permeability. This option can be set to Yes or No in case of oils. If set to Yes, the User has the option of defining a set of relative permeability curves, which will be used to change productivity of the system with changing water cut.
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The gravel pack selection and the type of completion (cased or open hole) are chosen from the main Options screen (in the PROSPER main menu) but some reservoir models have internal gravel pack data entries instead.
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In case gas coning option has been selected in main options, for oils the coning button is displayed to allow the activation of a dialog screen in which parameters for the calculation of rate-dependent GOR's can be entered
If the fluid is a gas or a condensate the format of the screen is very similar; only the reservoir and other model input selections vary for example, in gas systems, we have CGR and WGR instead of GOR and WC. The choice of reservoir models governs which subsidiary models (principally skin) are enabled. Thus, horizontal well models do not require a deviation skin data entry and some of the more complex reservoir models (e.g. multi-layer with dP friction loss) contain their own skin and gravel pack models. PROSPER Manual
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2.6.1.5 Data Input Screen The data input screen contains a set of data entry tabbed dialogs that become available depending on the selected IPR model. Only one dialog is displayed at any one time, corresponding to the tab selected as shown in the figure below
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The tabs are labelled as follows: · · · · · · Ü
Reservoir Model Mech/Geom Skin Dev/PP Skin Gravel Pack Relative Perm Viscosity The tabs are coloured according to the validity of the data on the corresponding dialogs. ·
If the tab is green, then the data are valid for the current system set-up. © 1990-2011 Petroleum Experts Limited
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·
If it is red, then the data are invalid or empty.
·
If the tab is grey, then this tab is not applicable to the current reservoir model (or model selection) and so is inaccessible.
The various screens, accessible by the bottom tabs comprise the dialog screens, where the input parameters for the selection are entered. Laid in the area below the Section and Action buttons. in case of the model selection screen it is mainly occupied with ways of choosing models, namely three list boxes, a drop-down list box and a push button.
For example figure above a Darcy reservoir model dialog encapsulated in the data input screen contained in the main entry screen. · The Reservoir Model tab is marked invalid (due to the unlikely reservoir thickness of –1 feet). ·
The Dev/PP Skin tab and relative permeability tabs are marked disabled. In this case it is because the ‘Enter Skin By Hand’ option is selected which is assumed to contain the deviation and partial penetration information. In the latter case relative permeability is simply not selected (see figure above, showing the model selection screen).
Notes on Data Validation: Ü
On each of the IPR Input screens there is a validate button. Pressing this button invokes a checking routine which flags for the any invalid entries.
Notes on Data Entry in IPR section In all the IPR input screens, for various options, the data may be required to be entered in one of the following ways: · ·
· Ü
Entering a value against a blank field Pressing a push button, which takes us further into another screen, where actual data required is entered as indicated against Dietz calculator on the screenshot above reported. Using a drop-down list. Some models require data entered for multiple layers (e.g. multi-layer and multi-layer with dP friction loss) and/or multiple completion zones (e.g. horizontal well with dP friction loss and Wong-Clifford deviation/partial penetration skin model). In dialogs with grid entry it is also possible to select, copy, cut and paste
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blocks of the table, using mouse drag operations and the buttons provided on the screen. As the data in a table are typically interdependent some consistency validation checks are carried out in addition to the range validation.
2.6.2 IPR Models for Oil and Water Wells The IPR model chosen depends upon the available data and the type of inflow sensitivities to be performed. Some of the main highlights are Ü
There are twenty inflow options, including the multi-lateral method described in Section 7.8, are available. The average reservoir pressure and reservoir temperature must be entered for all inflow performance models, except for multi-rate models. From the Multi-rate models the average reservoir pressure can be back calculated. If test data is available it can be entered and plotted against the calculated inflow. Well skin can be either directly entered or calculated using the Locke, Macleod or Karakas and Tariq methods for a mechanical/geometrical skin, and the Cinco/Martin-Bronz or Wong-Clifford methods for a deviation/partial penetration skin. Relative permeability curves are optionally used together with fluid viscosities (from PVT) to calculate the total fluid mobility for a given water cut. The calculated IPR can be matched to measured data and used to calculate IPR pressures for any rate and water cut. Relative permeability can be applied to all oil IPR models in PROSPER. Frictional pressure losses between multiple producing zones are accounted for in the Horizontal Well - friction dP and Multi layer - friction dP. A network algorithm determines the production from each zone while accounting for flowing pressure losses to find the total well production. These models can be combined with gravel pack and relative permeability models if the option is enabled (the former in the Options screen from the PROSPER main menu and the latter from the IPR main data entry screen).
Once a specific model is chosen and data entered for it, after which an IPR can be calculated using the Calculate button. The following sections list various inflow models that are available for oil wells. © 1990-2011 Petroleum Experts Limited
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2.6.2.1 P.I. Entry A straight-line inflow model is used above the bubble point based on the equation shown below. The Vogel empirical solution is used below the bubble point, the test point being the rate calculated using the following equation at bottom hole pressure equal to bubble point. The User input productivity index (PI) is used to calculate the IPR. The IPR rates are always Liquid Rates. Hence the PI refers to Liquid Rate.
Q = J ( Pr - Pb ) Where J is the Productivity Index, expressed as STB/(day psi). 2.6.2.2 Vogel The program uses the straight-line inflow relationship above the bubble point and the Vogel empirical solution below the bubble point. A single flowing bottom hole pressure and surface test rate is used to calculate the IPR, below the bubble point. From this IPR the rate and bubble point pressure are used to evaluate the PI for the straight-line part of the inflow above the bubble point. When calculating IPR sensitivities for reservoir pressure, PROSPER retains the correct well productivity. Otherwise, changing the reservoir pressure changes the Vogel well productivity. Pwf æ Pwf Q = 1 - 0.2 - 0.8çç Qmax Pr è Pr
ö ÷÷ ø
2
2.6.2.3 Composite This is an extension of the Vogel inflow solution (Petrobras method) that accounts for water cut. Vogel essentially decreases the inflow below bubble point because of gas formation. However, if the water cut is higher the inflow potential will increase and approach a straight-line IPR due to single-phase flow. The composite model captures this by using the following formulation. A test flow rate, flowing bottomhole pressure and water cut are required to be entered.
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2.6.2.4 Darcy The program uses the Darcy inflow equation above the bubble point and the Vogel solution below the bubble point. Required input is: · Reservoir permeability (total permeability at the prevailing water cut and GOR) · Reservoir thickness (thickness of producing reservoir rock, i.e. vertical thickness of net pay interval) · Drainage area · Well bore radius · Dietz shape factor (to account for the shape of the drainage area) 2.6.2.5 Fetkovich The Fetkovich equation for oil is a modified form of the Darcy equation, which allows for two phase flow below the bubble point. The Fetkovich equation can be expressed as: 2
2
Q = J ( Pr - Pb ) + J ' ( Pr - Pwf )
Enter the same inputs as for the Darcy example plus the relative permeability for oil. Skin can be entered either by hand or calculated using Locke's, Macleod's or the Karakas and Tariq method.
2.6.2.6 Multi-rate Fetkovich This method uses a non-linear regression to fit the Fetkovich model for up to 10 test points. The model is expressed as: Q = C (( Pr2 - Pwf2 ) / 1000) n
The fit values of C and n are posted on the IPR plot. If the reservoir pressure is not available, the program will calculate it. For producing wells, enter a reservoir pressure lower than the measured flowing bottomhole pressures. The program will dismiss the reservoir pressure that has been entered and calculate it. For injection wells, input a reservoir pressure higher than the test pressures entered. The program will then calculate the reservoir pressure.
2.6.2.7 Jones The Jones equation for oil is a modified form of the Darcy equation, which allows for both Darcy and non-Darcy pressure drops. The Jones equation can be expressed in the form: ( Pr - Pwf ) = aQ 2 + bQ © 1990-2011 Petroleum Experts Limited
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Where "a" and "b" are calculated from reservoir properties or can be determined from a multi-rate test. The same data as for the Darcy model plus the perforated interval is required. Skin can be directly entered or calculated using the available methods.
2.6.2.8 Multi-rate Jones This method uses a non-linear regression to fit for up to 10 test points for the Jones model. i.e. ( Pr - Pwf ) = aQ 2 + bQ
If reservoir pressure is to be calculated see Multi-rate Fetkovich above.
2.6.2.9 Transient This IPR method takes into account the change of deliverability with time. This method can be particularly important for tight reservoirs. Both the Darcy and Jones equations assume that the well has reached pseudo-steady state flow conditions. In tight reservoirs, the transient equation can be used to determine the inflow performance as a function of flowing time. Once the flowing time is long enough for pseudo-steady state flow to develop within the drainage radius, the Darcy inflow model is then used. Enter the same data as the Darcy example plus: · Porosity · Time
(Enter the reservoir porosity) (Time in days, must be greater than 0.5 days)
The transient IPR equation is:
Time is the flowing time since the last reservoir pressure equalisation up to the time of the analysis. If the flowing time exceeds , the deliverability is evaluated using , which is equivalent to using the pseudo-steady state Darcy model. The Transient IPR model in PROSPER is designed to · check whether the production is in the transient state or semi-steady state. · If it is in the transient state, then the IPR will be calculated using the equation mentioned above. · If the production has already reached the semi-steady state conditions, then the PROSPER Manual
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IPR will be calculated using the semi-steady state inflow equation The units used in the above transient IPR equation are oilfield units: Q = stb/d P = psig µ = cp Bo = rb/stb k = mD t = hours Ct = 1/psi h, rw = ft Note: Although the total saturation weighted compressibility is used in the literature, PROSPER only uses the fluid compressibility as the relative magnitude of the formation compressibility is such that it will have negligible impact on the pressure drop calculations. 2.6.2.10Hydraulically Fractured Well The hydraulically fractured well inflow model can be used to run sensitivities on hydraulic fracture designs. The model is transient and is particularly useful in determining the transient deliverability of a well after stimulation. Ü Gravel packs can be combined with the hydraulically fractured well IPR to model Frac-Packed wells Reservoir permeability
Total permeability at prevailing water cut
Formation thickness
Thickness of producing reservoir rock
Drainage Area Wellbore radius
Radius of the wellbore
DIETZ shape factor
Depends on the shape of the drainage area.
Time
Inflow is transient in early time.
Fracture Height
Hf - The fracture height is only used in Gas Wells to compute the Non-Darcy factor. The fracture height is not used for oil wells.
Fracture Half Length
Half length of the fracture
Dimensionless
Dimensionless fracture conductivity is a
key design
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Fracture Conductivity parameter in well stimulation that compares the capacity of the fracture to transmit fluids down the fracture and into the wellbore with the ability of the formation to deliver fluid into the fracture. K f bf Defined as: FCD = KR xf where: FCD Fracture Conductivity Kf
Fracture Permeability
bf
Fracture Width
Kr
Reservoir Permeability
xf
Fracture Half Length
The skin by hand is the 'Fracture Face Skin'. This can be set to zero if the frac program has been performed such that there isn’t an additional pressure drop in the fracture. If the frac program has been such that it leads to an additional pressure drop then this skin value can be increased. Clearly there cannot be a 'negative skin' associated with the 'fracture'. The analytical models such as karakas-tariq are not applicable for the fracture skin and are hence not available. The hydraulically fractured well model is based on the paper by Cinco Ley - SPE 6014. 2.6.2.11Horizontal Well - No Flow Boundaries This steady-state inflow model is based on the work of Kuchuk and Goode. It assumes that the horizontal well is draining a closed rectangular drainage volume that is bounded by sealing surfaces. The well can be placed anywhere within the drainage region. The pressure drop along the well bore itself is not taken into account. This model may not be suitable for long horizontal sections drilled in high productivity reservoirs. Horizontal well - friction dP IPR should be used in such cases. Enter: Ü
The definitions of symbols for various parameters to PROSPER horizontal well model are as per this manual and not necessarily on basis of the reference paper.
· Reservoir permeability (Total permeability at prevailing water cut) · Reservoir thickness ) · Well bore radius PROSPER Manual
(Thickness of producing reservoir rock h
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· Horizontal anisotropy
· · · · · · ·
(Ratio of Ky/Kx where Kx is permeability in the direction of the horizontal well and Ky is the permeability perpendicular to the horizontal well) Vertical anisotropy (Ratio of Kz/Ky where Kz is the vertical permeability) Length of well (Horizontal section L) Length of drainage area (Reservoir dimension parallel to well Lx ) Width of drainage area (Reservoir dimension perpendicular to well Ly) Distance from length edge to centre of well ( Xw) Distance from width edge to centre of well ( Yw) Distance from bottom of reservoir to centre of well ( Zw)
A sketch outlining the main geometric parameters is shown below:
2.6.2.12Horizontal Well - Constant Pressure Upper Boundary The reservoir geometry is the same as for the No Flow Boundaries case, except for a constant pressure upper boundary. The pressure drop along the well bore itself is not taken into account. This model requires the same input data as the Horizontal Well Bounded Reservoir model above. The plots below compares PROSPER calculated IPR values with those obtained by Kuchuk and Goode for a well in the centre of a 4000’ by 4000’ square reservoir.
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PROSPER Horizontal Well IPR vs Fine Grid Simulation 35 Anisotropy 30 0.01 0.1
25
h = 50' zw = 25' rw = 0.25' kh = 50 md vis = 1 cp
P.I. (BOPD/psi)
1.0 20
Simulator - Lines PROSPER - Symbols
15 4000'
4000'
10
5
0 0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
L1/2/Lx
2.6.2.13Multi-Layer Inflow The multi-layer inflow model allows up to 50 discrete reservoir layers to be entered as shown in the following example input screen:
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Each layer can have different reservoir pressures, inflow models and fluid properties. The oil gravity, GOR and water cut may be entered for each layer. The produced fluid properties in the well bore are determined from the summation of the individual layer contributions. The summation accounts for cross flow between layers having different pressures. Each layer can be gravel packed if desired. Both Injectors and Producers can be modelled. For cases where the zones are separated by significant depth or friction pressure losses are significant, the Multi-layer - dP Loss network IPR model should be used. Ü
If PVT matching has been used in the PVT section, it is assumed that it was performed on the commingled layer fluids. The fit parameters generated will be applied to all PVT calculations for all layers in determining the combined inflow performance.
To use the Multi-Layer IPR, enter the reservoir temperature then click Input Data to enter the tab-controlled screen, and then click on the Reservoir Model tab button. For each layer, select the inflow model from: Darcy, Multi-rate Jones, or PI Entry methods then enter the layer PVT properties, average pressures, thickness and skins. For each layer, click the Layer Data button and enter the information required by the inflow model. Ü
To facilitate rapid comparison of flow rates using different completion options, select a Null IPR type for a layer i.e., from the Layer Model drop-down dialogue box select the blank (no text) option. This effectively turns the layer off. To return it to production, re-select the original IPR type, and the layer parameters etc. will be re-instated when the IPR is re-calculated.
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The Multi-Layer IPR solves the combined contribution from each producing layer at the intake node. This effectively places each layer at the same depth. The reservoir pressure entered for each layer should therefore be referenced to the intake node depth.
2.6.2.14External Entry This option allows an externally generated IPR data set to be imported or directly entered. Up to five tables can be entered to allow sensitivities to be calculated on any arbitrary set of variables. For example, IPRs for a range of reservoir pressures calculated by a simulator could be input using this option. An example of an external entry IPR input screen is shown below:
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External IPR tables can also be imported from ASCII files. The file format is given in Appendix D of the PROSPER User Guide. Curve Label and Units These fields allow the user to identify the curves with a label and units. Note that label and units will appear only in the Sensitivity calculation in the list of sensitivity variables, where one can interpolate among the entered curves.
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Import/Export It is possible to import or export the IPR tables for the External Entry IPR 2.6.2.15Horizontal well - dP Friction Loss in Wellbore To adequately model horizontal well inflow in high permeability reservoirs, it is necessary to account for pressure loss along the horizontal section. PROSPER divides the horizontal section into 20 sections and a network algorithm solves for zone production and well bore pressure. Pressure loss between zones is accounted for. The Horizontal well - dP Friction input screen is shown below:
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The reservoir parameters entered in the upper section of the screen determine the overall well productivity using the selected model. The zone parameters are used by the network algorithm to re-scale the overall productivity on a zone-by-zone basis. A description of the input parameters follows: Reservoir Parameters · Horizontal Well Model (Model used for overall well productivity) · Reservoir permeability (Total permeability at prevailing water cut) · Reservoir thickness (Thickness of producing reservoir rock h) · Well bore radius (Radius of open hole rw) · Horizontal anisotropy (Ratio of Ky/Kx where Kx is permeability in the direction of the horizontal well and Ky is the permeability perpendicular to the horizontal well) · Vertical anisotropy (Ratio of Kz/Ky where Kz is the vertical permeability) · Length of well (Horizontal section L) · Length of drainage area (Reservoir dimension parallel to well Lx) PROSPER Manual
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· Width of drainage area (Reservoir dimension perpendicular to well Ly) · Distance from length edge to centre of well Xw) · Distance from width edge to centre of well Yw) · Distance from bottom of reservoir to centre of well Zw)
( ( (
The horizontal well models available are: Kuckuk and Goode (bounded and constant pressure boundary) Babu & Odeh Goode / Wilkinson partial completion (bounded and constant pressure boundary) The reservoir parameters are entered as for the original infinite conductivity (no pressure loss) horizontal well model. Ü
Geometric definitions vary between published horizontal well inflow models. Ensure that geometric parameters entered in PROSPER are consistent with the above definitions. Refer to the Horizontal Well IPR sketch for details.
Zone Parameters Data for up to 20 zones can be entered. The required inputs are as follows: · · · · · · ·
Zone Type (Blank, Perforated or Open Hole) Skin method (Enter by Hand, or Karakas & Tariq for perforated zones) Gravel Pack (Yes or No) Zone Length (Length of zone along the well) Zone Permeability (Average permeability at the prevailing water cut) Flowing Radius (Internal radius of the completion tubing) Zone Roughness (Roughness for zone friction calculation)
These parameters describe the local permeability and the flow path along the well bore. Click the Zone Data button to enter details such as skin and perforation parameters. If the Skin Method is Enter by Hand, the skin and open hole radius are required. If Karakas & Tariq is selected, then enter the perforation details as in Section 7.4.1 and PROSPER will estimate the zone skin. If the zone is to be gravel packed, this data is entered under Zone Data. Ü
To allow comparison of the IPR with and without friction losses, setting the zone roughness to zero turns off the friction pressure drop calculation entirely rather than calculating friction for a smooth pipe
Coning Calculations in Horizontal wells The Ben Dikken and Chaperon correlations prediction of critical coning rates for gas, water or gas and water have been implemented. From the Horizontal well - dP Friction data entry screen click Coning to display the Coning Calculations screen: © 1990-2011 Petroleum Experts Limited
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Enter a production rate and porosity then select the required coning calculation method. Click Calculate to find the critical rate and time to breakthrough for the rate entered. The pressure along the well bore for the specified rate is calculated and displayed by clicking Plot.
The production contribution from each zone can be displayed as: Rate per Unit Length Percentage production PROSPER Manual
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Cumulative percentage production An example of a rate per unit length plot is shown below:
Ü
The Horizontal Well - friction dP IPR models the pressure at the heel of the well as a function of pressure. The intake node is therefore the heel of the well. The heel should be the last node entered in System Equipment and Deviation Survey tables - it is not necessary to enter details of the horizontal producing section except in the IPR.
2.6.2.16Multi-Layer - dP Loss in Wellbore The Multi-Layer dP Loss in Wellbore model can be used to model the production from multi-layered reservoir systems where pressure losses in the wellbore are significant. PROSPER iterates until the production from each zone and the well pressures converge at the solution rate. The effect of pressure drop between zones and cross flow is accounted for. example of a Multi-Layer - dP Loss input screen is shown below:
An
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This screen allows for the entry of up to 50 layers. To enter PVT, IPR data (permeability, test rates etc. depending on the IPR model selected) and layer skin, click the appropriate button to display the input screen. The depth entered for TOP is the depth for which the IPR is to be evaluated. This is normally the same as the deepest depth entered in System Equipment, but it can be set to surface or other value. The input data required are: · · · · ·
Layer Type Measured Depth True Vertical Depth Layer Pressure Layer Flowing Radius drops)
·
The layer flowing radius is the radius of the pipe connecting the layers i.e., 0.5 x tubing I.D. The wellbore radius (rw) is the radius of
· · · · · ·
the drill bit. Layer IPR Model Layer Skin Model Layer Gravel Pack Layer PVT Data Layer Parameters Layer Skin
(Either Blank, Perforated or Open Hole) (Measured depth of the bottom of layer n) (TVD of the bottom of layer n) (Pressure at the bottom of layer n) (Well radius for calculating inter layer pressure
(Select from Darcy, Multi-rate Jones, P.I. Entry) (Enter by Hand or Karakas & Tariq) (Yes or No) (GOR, Oil and Gas Gravity plus Water Cut) (Relevant parameters for the selected IPR model) (Relevant parameters for the selected IPR model)
The IPR at surface can be calculated by entering the surface elevation for TOP depth and a blank zone from surface to the shallowest producing zone. Use blank zones with PROSPER Manual
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appropriate reduced I.D. to simulate the effect of sliding sleeves and flow controls in a multi-zone completion. Click Calculate and the IPR for each layer and the summation will be calculated and displayed on a plot as follows:
To list the layer production in detail, click Results and scroll through the layer results one by one. An example results screen is shown below:
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Scroll from the selection menu to view the results for each of the layers. Gravel pack and well skin etc. can be seen by scrolling to the right of the results table. Negative layer production rates indicate cross-flow into the layer.
Ü
If a zero roughness is entered, then inter-layer pressure drops are not computed. The layer pressures are then equivalent to a potential referred to the depth of the TOP layer. The calculations are then equivalent to the simpler Multi-Layer IPR without dP model.
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The multilayer option is now available for dry gas and gas condensate model
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The Gravel Pack sand control option is only available for the Multi-Layer dP Loss in Wellbore IPR model and can be activated via the Options menu
2.6.2.17SkinAide The Elf inflow and skin calculation method is incorporated in PROSPER. API perforation characteristics can be used to estimate perforation damage given casing and formation properties. A detailed description of SkinAide is given in Section 7.7. 2.6.2.18Dual Porosity This model is useful for naturally fractured reservoirs where the matrix (formation) porosity is greater than the fracture porosity and the matrix permeability is much smaller than the fracture permeability, but not negligible. It requires the entry of the following parameters: fracture permeability, reservoir thickness, drainage area, well-bore radius, porosity, time, storativity ratio and interporosity coefficient. The latter two parameters are defined as follows: 1. Storativity ratio, w = ff cf / ( ff cf + fm cm) where ff is the fracture porosity, cf is the fracture compressibility, fm is the matrix porosity and cm is the matrix compressibility. 2. Interporosity, l = a km rew^2 /kf where a is a shape factor (see Warren, J.E. and Root, P.J.: "The Behaviour of Naturally Fractured Reservoirs.", SPE 426, SPEJ (Sept. 1963), 245-255.), km is matrix permeability, rew^2 is effective well radius squared and kf is fracture permeability. 2.6.2.19Horizontal Well with Transverse Vertical Fractures The horizontal well with transverse vertical fractures is based on a model proposed by T. M. Herge and Leif Larsen in the SPE paper 28845. The model calculates an effective wellbore radius based on fracture conductivity, fracture size, wellbore radius and PROSPER Manual
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number of fractures. The fractures are assumed to be uniformly distributed along the horizontal length of the well. This effective wellbore radius is then used in the “horizontal well - no-flow-boundaries” IPR model (based on the work of Kuckuk and Goode) to calculate the well productivity. This is for use with wells that are stimulated with one or more transverse vertical fractures. It is assumed that the fractures are circular, the well goes through their centre and they are evenly spaced. If there is one fracture it is in the middle of the well. The data to be entered are the same as those for a horizontal well, along with the fracture half-length and its dimensionless conductivity. The following points describe the method of performing the calculations. ·
The fracture half length, fracture conductivity, and number of fractures are used to calculate an equivalent wellbore radius. This calculation is based on the technique developed by Hegre and Larsen (SPE 28845)
·
The effective wellbore radius is then used in the Horizontal Well – No Flow Boundary model to compute the IPR of the well.
The ‘Horizontal Well - Transverse Vertical Fracture’ model, in some cases calculates decreasing AOF with increasing vertical anisotropy. This is counterintuitive and is due to the calculated equivalent wellbore radius exceeding the input reservoir thickness in which case the well is effectively located on the edge or outside the defined drainage area. The model is no longer applicable for these cases. 2.6.2.20Thermally Induced Fracture Model 2.6.2.20.1 Overview This IPR model is enabled when Well Type Injector is set in the main program Options. The algorithm follows the framework outlined in: SPE 30777, Thermally Induced Fractures: A Field-Proven Analytical Model. SPE Reservoir Evaluation & Engineering, February 1998. J-L. Detienne, Max Creusot, Nicolas Kessler, Bernard Sahuquet and J-L. Bergerot. Information was also assembled from SPE 7964 (radial reservoir temperature profile) and SPE 11332 (coefficient for thermo-elastic stress equation). Note that the temperature profile derivation uses the same basis as the work of de Lauwerier referred to in SPE 30777. SPE 7964: Analytical Definition of the Overall Heat Transfer Coefficient, A. B. Zolotukhin. SPE 11332: The Effect of Thermo-elastic Stresses on Injection Well Fracturing, T.K. Perkins and J.A. Gonzalez. This model is concerned with the thermo-mechanical effects induced by injecting cold water into a hot reservoir. The method first tests whether a calculated Pwf rises above the reservoir stress around the well bore. If this occurs then a fracture is assumed to © 1990-2011 Petroleum Experts Limited
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propagate and the Pwf at the fracture tip is equated to the reservoir stress (i.e. equilibrium) by iterating on the fracture length. The fracture’s effect is incorporated in a skin term, and two stress effects are considered; a thermo-elastic one (varies with injection temperature) and a poro-elastic one (varies with Pwf). The stress at the wellbore is calculated by adding these effects to the initial reservoir stress. The Pwf is calculated using varying fluid and geometric properties (inner and outer radii) and a Darcy-like model in three circular zones. The first (inner) is water that is still cool, the second is water that has warmed up, and the third (outer) is the original reservoir. The IPR calculated by this model consists, therefore, of two different zones with a breakpoint where the fracturing occurs. See the following figure.
The model is not valid for uncontrolled hydraulic fracturing where the fracture length may be several hundred feet. The fracture should not extend beyond the so-called cooled injection zone, the extent of which is calculated using the temperature profile referred to above.
2.6.2.20.2 Data Entry The Thermally Induced Fracture model reservoir data screen is split into two tabbed screens, one handling 'Injecitivity Index' parameters, and one handling 'Thermomechanical' parameters. Also, it is required to enter the injected fluid temperature in the model selection screen. PVT parameter PROSPER Manual
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Injected Fluid Temperature Injectivity Index Parameters Reservoir permeability (Total permeability) Formation thickness (Thickness of producing formations) Drainage area DIETZ shape factor (Depends on the shape of the drainage area). Wellbore radius Porosity (Enter the reservoir porosity) Time (Time in days, must be greater than 0.5 days) Mean Historical Injection Rate Thermo-mechanical Parameters Initial Reservoir Stress Sweep Efficiency Injected Fluid Specific Heat Capacity Overall Reservoir Conductivity Overall Reservoir Specific Heat Capacity Overall Reservoir Density Top and Bottom Surroundings Conductivity Top and Bottom Surroundings Specific Heat Capacity Top and Bottom Surroundings Density Reservoir Thermal Expansion (thermo-elastic correlating coefficient, relates temperature perturbation to stress perturbation) Biot's Constant (poro-elastic correlating coefficient, relates pressure perturbation to stress perturbation) Poisson's Ratio Reservoir Young's Modulus
2.6.2.21Relative Permeability Curves Relative permeability curves are optionally used together with fluid viscosities (from PVT) to calculate the total fluid mobility for a given water cut. The calculated IPR can be matched to measured data and used to calculate IPR pressures for any rate and water cut Relative Permeability Calculation Details If you have selected the Correction for Vogel option on the main IPR screen then the modelling is extended to include Gas Relative Permeability Curves. The calculated IPR can be matched to measured data and used to calculate IPR pressures for any rate, water cut and GOR Relative permeability can be applied to all oil IPR models in PROSPER.
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The relative permeability for oil and water is a function of the reservoir water saturation. If the relative permeability curves have been defined, the total mobility (oil, water and gas) can be determined. This enables the producing drawdown (IPR) to be calculated as a function of both water cut and production rate. Enter the following data for both oil and water (and optionally Gas): Residual Saturation
Parameter indicating the minimum saturation above the related phase becomes mobile
Endpoint Relative Permeability
Maximum relative permeability
Corey Exponent
Parameter defining the slope of the relative permeability curve. A Corey exponent of 1.0 defines straight line relative permeability curves. Values greater than 1 give a concave upwards curve i.e. delayed water breakthrough. Corey exponents less than 1 define a concave downwards relative permeability curve i.e. early water breakthrough.
Water cut during test
Matching measured and calculated IPR pressures establishes the well productivity for the prevailing water cut. To allow PROSPER to re-calculate the IPR for other water cuts, the water cut during test is used to determine the reference water saturation for the test conditions.
GOR during test (optional)
Matching measured and calculated IPR pressures establishes the well productivity for the prevailing GOR. To allow PROSPER to re-calculate the IPR for other GORs, the GOR during test is used to determine the reference gas saturation for the test conditions.
To enter lab relative permeabilities, click Test Data. Enter your test data and click OK to display the plot again. If necessary, adjust the values of Corey Exponents for oil and water until PROSPER's calculated relative permeability curves fit the measured data points. Having entered and verified the relative permeability data, click Finish to quit the plot, then OK to return to the IPR screen. When relative permeability is being used, water cuts for both the test data and that used to calculate the IPR curve are required. The water cut during test value will be carried over from the relative permeability input screen. The water cut for calculation value can be subsequently changed to see the effect on the calculated IPR. The same will apply for GOR if you have selected the Correction for Vogel option.
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2.6.2.21.1 Test Data To enter lab relative permeabilities, enter your test data and click Done to display the plot again. If necessary, adjust the values of Corey Exponents for oil and water until PROSPER's calculated relative permeability curves fit the measured data points. 2.6.2.21.2 Plot Relative permeability curves are optionally used together with fluid viscosities (from PVT) to calculate the total fluid mobility for a given water cut. The calculated IPR can be matched to measured data and used to calculate IPR pressures for any rate and water cut. Relative permeability can be applied to all oil IPR models in PROSPER. The relative permeability for oil and water is a function of the reservoir water saturation. If the relative permeability curves have been defined, the total mobility (oil, water and gas) can be determined. This enables the producing drawdown (IPR) to be calculated as a function of both water cut and production rate. The following options are common to all plots Finish
Close plot and return to the previous screen.
Main
Close plot and return to the main PROSPER screen.
Annotate
Add annotations to your plot.
Scales
Rescale your plot. You will need to enter new minimum and maximum values for the X and Y axes.
Labels
Change the plot labels
Replot
Redraw the plot, using the original settings. Use this after you have zoomed the plot.
Output
Use this option to generate a printer, plotter or file copy of your plot, or to transfer it to the clipboard.
Colours
This option enables you to change the colours of the plot background, outline, axes and plot lines and/or labels to generate a screen display more to your liking. Once you have made your selection, make sure you use the Save option to save your selection.
Options
Use this option to change plotting defaults such as number of grids per axis, grid line types, scaling methods etc.
Help
View this Help screen
If you wish to view a particular section of your graph more closely, you can magnify or zoom in on any portion of the plot. To magnify, first place the plot cross-hair cursor over the area of interest. Next , press down the mouse left hand button and keep the button © 1990-2011 Petroleum Experts Limited
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depressed. A rectangle will appear which you can "stretch" or drag over the area you want to magnify. Release the mouse button and you will automatically zoom in on the area inside the rectangle. When selecting the area to magnify, first place the cross-hair cursor on any outside corner of the box you wish to draw, drag the mouse in the diagonally opposite direction. When the magnifying rectangle is large enough, release the mouse button.
2.6.2.21.3 Relative Permeability Calculation Details Relative Permeability Calculation Details Oil and Water Only The process is as follows:Use the test water cut and the PVT model to calculate the downhole fractional flow Fw. Calculate the water and oil saturations that give the Fw. Note we set Sg=0 as the IPR is already corrected for gas with the Vogel correction. Calculate the relative oil and water permeabilities using the relative permeability curves and the oil and water saturations. Calculate a test mobility from Mt = Kro/(µ oBo) + Krw/(µ wBw) The water and oil viscosities are calculated from the test reservoir pressures and the PVT. We should actually use the absolute oil and water relative permeabilities but since the only use of the total mobility is when divided by another mobility, the final results will be correct. Whenever an IPR calculation is done:Calculate the PVT properties using the current reservoir pressure and the PVT model. Calculate the downhole fractional flow from the current water cut. Calculate the water and oil saturations that give the Fw. Note we set Sg=0 as the IPR is already corrected for gas with the Vogel correction. Get the relative permeabilities for oil and water from the relative permeability curves. Calculate the current mobility M as shown above. Modify the PI using:PI = PIi * M/Mt In the above method we do not take into account the reduction in oil mobility due to any increase in the gas saturation. When calculating the Sw and So for a particular Fw we set Sg=0.0. Oil, Water and Gas If you wish to take the effect of increasing gas saturation into account then select the PROSPER Manual
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Correct Vogel for GOR option. You will also be required to enter a Test GOR - this is a produced GOR. The process will now be as follows:Use the test water cut, test GOR and the PVT model to calculate the downhole fractional flows Fw and Fg. Calculate the gas, water and oil saturations that satisfy the Fw, Fg and So+Sw+Sg=1.0. Calculate the relative oil and water permeabilities using the relative permeability curves and the oil, gas and water saturations. Calculate a test mobility from:Mt = Kro/(µoBo) + Krw/(µwBw) The water and oil viscosities are calculated from the test reservoir pressures and the PVT. We should actually use the absolute oil and water relative permeabilities but since the only use of the total mobility is when divided by another mobility, the final results will be correct. Whenever an IPR calculation is done:Calculate the PVT properties using the current reservoir pressure and the PVT model. Calculate the downhole fractional flows Fw and Fg from the current water cut and produced GOR. Calculate the gas, water and oil saturations that satisfy the Fw, Fg and So+Sw+Sg=1.0. Get the relative permeabilities for oil and water from the relative permeability curves and the oil, gas and water saturations. Calculate the current mobility M as shown above. Modify the PI using:PI = PIi * M/Mt 2.6.2.22Coning Calculation In addition to the coning model implemented for the Horizontal Well with dP Friction Loss model, a gas coning option can be chosen from the Options screen in the main menu. This applies to all oil IPR models. It modifies the solution GOR by multiplying it by a weighting factor greater than 1, which is a positive function of the liquid rate. The output is a total, or produced, GOR. The model implemented was originally developed for high permeability reservoirs (see Urbanczyk, C.H, and Wattenbarger, R.A., "Optimization of Well Rates under Gas Coning Conditions.", SPE Advanced Technology Series, Vol. 2, No. 2, April 1994). The following data are required to calculate the total GOR from a rate: · · · · ·
Reservoir permeability Perforation height (vertical distance from perforation top to bottom) Vertical anisotropy Vertical distance from perforation top to gas-oil contact Three correlating parameters: F1, F3 and an exponent © 1990-2011 Petroleum Experts Limited
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If the gas coning is enabled then a Coning button appears on the model selection dialog screen. Clicking on this brings up a dialog that allows the correlating parameters to be tuned. There is an automatic matching facility, which calculates F3 from the other data and a (rate, GOR) coordinate. Also, the GOR can be calculated from different rates whilst in this screen in order to verify the parameters. Ü
It is recommended that this model be calibrated against measure rate versus produced GOR data before using it as a predictive tool.
2.6.3 IPR for Gas and Retrograde Condensate Sixteen inflow options are available, including a multi-lateral inflow model. The choice depends upon the information available and the type of sensitivities that will be done. If multi-rate test data is available, the modelled IPR can be matched to the measured data. As for oil, Gas inflow models are divided between design and production applications. Calculated IPR models can be used to estimate productivity for different completion options. Other models are available for estimating productivity from measured flowing pressures. The average reservoir pressure and reservoir temperature must be entered for all inflow performance models, however both the Multi-rate C and n and Multi-rate Jones models can be used to calculate the reservoir pressure from production test data.
2.6.3.1 Jones The Jones equation for gas is a modified form of the Darcy equation, which allows for both laminar and non-Darcy flow pressure drops. The Jones equation can be expressed in the form:
PR2 - Pw2f = a Q 2 + b Q Where "a" and "b" are calculated from reservoir properties or "a" and "b" can be determined from a multi-rate test. Required data entry is: · Reservoir permeability (Total permeability) · Formation thickness (Thickness of producing reservoir rock) PROSPER Manual
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· Drainage area · Wellbore radius · Dietz shape factor (Depends on the shape of the drainage area) Ü
The Jones IPR model is discouraged to use with high reservoir pressures as the assumption of the model is to keep 1 / µ Z constant at pressures >2400psig.
2.6.3.2 Forchheimer The Forchheimer equation expresses the inflow performance in terms of a laminar and a non-Darcy pressure drop coefficients expressed as:
PR2 - Pw2f = a Q 2 + b Q The "a" and "b" factors are input parameters for the Forchheimer IPR model. 2.6.3.3 Back Pressure In this form of the back pressure equation:
Q = C (PR2 - Pw2f ) n C is determined from the reservoir pressure and reservoir properties. Required input data are: · Reservoir permeability (Total permeability) · Formation thickness (Thickness of producing reservoir rock) · Drainage area · Wellbore radius (Open hole radius) · Dietz shape factor (Depends on the shape of the drainage area) · Exponent n (Between 0.5 and 1)
2.6.3.4 C and n This is the common form of the back pressure equation: © 1990-2011 Petroleum Experts Limited
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Q = C (PR2 - Pw2f ) n C and n can be determined from a plot of: Q versus (Pr2-Pwf2) on log-log paper. n is the inverse of the slope and varies between 1 for Darcy flow to 0.5 for completely nonDarcy flow. This option allows direct entry of C and n.
2.6.3.5 Multi-rate C and n Up to 10 test points can be entered and they will be fitted to the C and n back pressure equation for gas:
Q = C (PR2 - Pw2f ) n The fit values of C and n are posted on the IPR plot and listed in the IPR report. If the Reservoir Pressure defined in the IPR section is less than the highest value of the bottom hole pressure for the test points, then PROSPER will automatically calculate the reservoir pressure. For example, if there are three Well test data points defined for the IPR model as follows,
then if the reservoir pressure defined is less than 4036 psig, PROSPER w ill recalculate the reservoir pressure. If the reservoir pressure is greater than the highest FBHP specified, then the Multirate C & n model is designed to recalculate the C and n parameters so that the IPR w ill pass through the test data points and the reservoir pressure specified.
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It is advised to enter more than one test point. Using a single data point can generate a non-representative IPR profile.
2.6.3.6 Multi-rate Jones Up to 10 test points can be entered and they will be fitted to the Jones equation for gas expressed as: The fit values of a and b are posted on the IPR plot and listed in the IPR report. The multi-rate Jones IPR is a convenient way to determine a and b from well tests. These values can be entered in the Forcheimer IPR for calculating IPR sensitivities. The program will automatically calculate the reservoir pressure if it is not available. For producing wells, input a reservoir pressure lower than the measured pressures. The program will dismiss the reservoir pressure entered and calculate one. For injection wells, input a reservoir pressure higher than one of the pressures entered. The program will calculate the reservoir pressure. Ü
Note for injection wells. If flow test data for a producer has been fitted, the well will have the correct IPR if it is then converted to an injector.
2.6.3.7 External Entry Refer to External Entry for Oil.
2.6.3.8 Petroleum Experts The Petroleum Experts inflow option uses a multi-phase pseudo pressure function to model the reduction in well productivity resulting from increasing liquid saturation in condensate wells. It assumes that no condensate banking occurs and that all the condensate that drops out is produced. Transient effects on P.I. are accounted for.
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The following data is required to be entered: · Reservoir permeability (Either total, or effective permeability at connate water saturation) · Formation thickness (Thickness of producing reservoir rock) · Drainage area · Dietz shape factor (Depends on the shape of the drainage area) · Wellbore radius (Open hole well radius) · Perforated interval TVD of the height of perforations for the well · Porosity (Average over producing section) · Time (Refer to Transient IPR for Oil - Section 7.2.9) · Connate water saturation PROSPER Manual
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(Used in relative permeability calcs. - see below) · Permeability entered (Either total or effective at Swc) · Non-Darcy coefficient (Enter by hand or PROSPER can calculate it) The non-Darcy coefficient can be entered from a well test where available or calculated using a correlation. The D factor calculation is based on equations 8.24 and 8.27 from Chapter 8 of ‘Fundamentals of Reservoir Engineering’ by L. Dake. Since the Petroleum Experts IPR model calculates flow profile during transient conditions, the constant in equation 8.27 is replaced by 1637. This is based on the Essis-Thomas equation for flow during transient conditions. The non-Darcy D-factor is calculated as a product of the following two variables: D = A1*A2 Where: A1 = 3.161E-12 βTabs SG / (µ ghperf 2rw ) A2 = kabs h / (1637Tabs ) keff = kabs (1-Sw c )2 β = 2.73E10 / keff 1.1045 The following diagram illustrates how PROSPER treats total and effective permeability in the Petroleum Experts IPR model: Petroleum Experts IPR Relative Permeability Method
Relative Permeability
Krl 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
Krg when effective permeability is entered
Krg'
Krg when total permeability is entered
Slc 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Liquid Saturation
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The mass flow rate of each phase is directly proportional to its mobility (k/m), Kr’s can be determined using PVT and the surface production rates. This technique is used to determine the reduction in productivity as a function of the produced liquid ratios. The derivation of the technique and details of the equations used are given in Appendix B.
2.6.3.9 Hydraulically Fractured Well Please refer to Hydraulically Fractured IPR model in the Oil IPR section. Additional input data for gas and condensate applications are connate water saturation, a nonDarcy flow factor and either relative permeability to gas or total permeability. 2.6.3.10Horizontal Well - No-Flow Boundaries Please refer to Horizontal Wells in OIL IPR section. Additional input data for gas and condensate applications are connate water saturation, a non-Darcy flow factor and either relative permeability to gas or total permeability.
2.6.3.11Multi-layer Inflow The multi-layer inflow model allows up to 50 discrete reservoir layers to be entered each with different reservoir pressures, inflow models and fluid properties. Each layer can be gravel packed if desired. Both Injectors and Producers can be modelled. The gas gravity, CGR and WGR must be entered for each layer. The produced fluid in the well bore is equivalent to the summation of the individual layer contributions. Refer to Multi-layer Inflow for Oil for more details. 2.6.3.12Horizontal Well - dP Friction Loss in Wellbore Refer to Horizontal Well - dP Friction for Oil. For Gas, PROSPER uses the Petroleum Experts IPR method for steady-state flow. The Reservoir porosity and connate water saturation are required to be input in addition to the parameters described in the Horizontal Well- dP friction loss model in the Oil IPR section.
2.6.3.13Dual Porosity Please refer to the Dual Porosity model in the IPR for Oil section. Additional input data for gas and condensate applications are connate water saturation, a non-Darcy flow factor and either relative permeability to gas or total permeability.
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2.6.3.14Horizontal Well with Transverse Vertical Fractures Please refer to Horizontal Well with Transverse Vertical Fractures in the IPR for Oil section. Additional input data for gas and condensate applications are connate water saturation, a non-Darcy flow factor and either relative permeability to gas or total permeability.
2.6.3.15Multi-Layer - dP Loss in Wellbore The Multi-Layer dP Loss in Wellbore model can be used to model the production from multi-layered gas reservoir systems. Refer to the Multi-Layer dP Loss model for oil wells for further details. 2.6.3.16Modified Isochronal Inflow Model A type of deliverability test conducted in gas wells to generate a stabilized gas deliverability curve (IPR). This test overcomes the limitation of the isochronal test, which requires long shut-in times to reach the average reservoir pressure. In the modified isochronal test, the shut-in periods are of equal duration, as are the flowing periods. The final shut-in pressure before the beginning of the new flow is used as an approximation of the average reservoir pressure. The same procedure is typically repeated four times. A stabilized point (pseudosteady state) is usually obtained at the end of the test. Modified isochronal tests are commonly used in gas wells, because they require less time and money to produce results comparable to the isochronal test. This IPR model is based on standard Back Pressure Model
The flow at any selected rate should be continued long enough for the reservoir to approach steady-state (stabilized) conditions. The time to reach stabilized conditions is called the readjustment time. For wells with wide well spacing (large drainage radius values), low permeabilities, or high gas compressibilities (low reservoir pressures), large readjustment times can be expected. In cases where the readjustment time exceeds the duration of each test, the test data can be corrected to isochronal conditions and then to stabilized conditions as described below. When a well is tested from an initial steady state shut-in condition, the increase in drainage radius with time is not dependent upon the rate. Therefore, separate flow tests conducted for the same length of time will reach the same drainage radius. © 1990-2011 Petroleum Experts Limited
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When a well is not shut-in between tests until steady state is reached, successive tests will indicate values of (P2res – P2wf) which are too large because of the increasing drainage radius. For the general case, a table of correction factors to be applied to (P2 2 res – P wf) to obtain an isochronal performance curve from conventional performance data can be calculated as follows: Flow Correlation Factors The back pressure equation coefficients ‘C’ and 'n' are obtained by non-linear regression using the isochronally corrected data. 'n', the reciprocal of the slope of this line, is constrained to a value between 0.5 and 1. Although 'n' is constant, the coefficient 'C' is not the same at stabilized flow conditions as it is at isochronal conditions. It is calculated using the same technique as before, regressing on ‘C’ and keeping ‘n’ constant, after adjusting the isochronal (P2res - P2wf) values to stabilized conditions using a variation of the following equation.
The time to stabilisation is calculated as follows:
2.6.3.17Forchheimer with Pseudo Pressure This IPR model is based on the Forcheimer IPR using pseudo-pressure function instead of pressure:
where the pseudo-pressure function Y is defined as: PROSPER Manual
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a and b are the input parameters for the IPR model. NOTE: The a and b parameters for the pseudo pressure Forcheimer IPR are not the same as the a and b parameters used in the pressure squared Forcheimer IPR. 2.6.3.18Multirate Forchheimer with Pseudo Pressure This IPR is based on the Forchheimer IPR with pseudo-pressure (refer to previous section):
The a and b parameters are here determined by means of multi-rate tests data.
2.6.4 Skin Models PROSPER divides the total skin into two parts. These are: · ·
Mechanical / Geometric Skin. Deviation / Partial Penetration
The skin values could be either: · ·
Entered by Hand Calculated Using Models.
2.6.4.1 Mechanical/Geometrical Skin Enter Skin by Hand If a reliable skin value is available from transient well testing, then this value should be directly entered by selecting the "Enter by hand" option. Ü
It is assumed that this value will contain deviation and partial penetration information. In case the entered skin is only mechanical skin, there is an option of enabling the Wong and Clifford model for deviation and partial penetration in the input screen for the skin itself.
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PROSPER provides 3 methods of estimating a mechanical/geometrical skin factor using input parameters such as perforation geometry, depth of damage etc. The skin estimation models provided in PROSPER are those of: · Locke · McLeod · Karakas and Tariq The required input parameters are often difficult to accurately define, therefore the absolute value of the calculated skin often cannot be precisely predicted. The power of these techniques is their ability to assess the relative importance of completion options on the overall value of well skin. The Elf SkinAide inflow method can also be used to estimate skin pressure drops for cased- and open-hole completions with and without gravel packs. PROSPER can also be used to estimate the value of the skin pressure drop across the completion and the proportion of the total pressure drop attributable to the various completion elements. Karakas and Tariq has been found to give good results in many field applications. The following input data are required: · Reservoir permeability saturation) · Perforation diameter · Shots per foot · Perforation length · Damaged zone thickness · Damaged zone permeability · Crushed zone thickness · Crushed zone permeability · Shot phasing · Vertical permeability · Wellbore radius
(Effective permeability at connate
water
(Entry hole diameter) (Effective perf. length in formation) (Thickness of invasion) (Permeability in invaded zone) (Crushing associated with perforation) (Reduced permeability near perf. tunnel)
(Enter the open hole radius, not casing I.D.)
An example of the input data for the Karakas and Tariq method is shown below:
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A sketch outlining the main geometric variables is shown in the figure below.
Enter the requested data and, having entered some reservoir model data, press Cal culate to display an IPR plot. The plot shows the pressure drop resulting from the total skin as well a breakdown of the individual factors contributing to the total skin as per the following example. The individual factors to be plotted can be chosen from the V ariables menu option of the plot window.
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This plot is useful to assess the efficiency of a particular perforating program by allowing the User to instantly assess the completion pressure loss resulting from different perforation options. For gravel packed wells, the value of skin posted on the plot does not include the gravel pack skin. Click Results on the IPR plot screen to display the breakdown of dP's resulting from each completion element. Enhancement to the skin modelling options in PROSPER is the ability to apply the API RP43 to determine the actual length and diameter of perforations (figure below).
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Note on Skin: Locke's technique is valid for shots per foot of 1,2,4,6,8,10,12,and 16.
2.6.4.2 Deviation/Partial Penetration Skin In PROSPER three models are available to model the Deviation and Partial Penetration Skin: · Cinco / Martin-Bronz · Wong-Clifford · Cinco (2) / Martin-Bronz The Cinco / Martin-Bronz requires the following data: · Deviation angle of well · Partial penetration fraction · Formation vertical permeability The Cinco / Martin-Bronz is based on two correlations. The Deviation Skin is calculated using the Cinco's method, whereas the Partial Penetration skin is calculated using the Martin-Bronz method. The Cinco / Martin-Bronz model does not consider the anisotropy in the reservoir, that is, it considers the reservoir as isotropic. The Vertical Permeability entered in the Deviation and Partial Penetration Skin is only used for calculating the Partial Penetration. This model is based on a correlation. The validity of this extends to wells up to 65 degrees. For a higher deviation well the Wong Clifford Model should be used The Wong-Clifford model can compute a skin for multiple completions. The WongClifford model does not have a separate calculation for the deviation & partial penetration skin - it is a point source solution that calculates a skin that combines all of the skin effects in one value. This total skin is placed in the Deviation skin column and the partial penetration skin is set to zero. This model requires the following data entered: 1. Reservoir parameters: PROSPER Manual
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Formation vertical thickness Well-bore radius Drainage area Dietz shape factor Formation vertical permeability ratio Local vertical permeability ratio Horizontal distance from well to reservoir edge Depth of top of reservoir
2. Completion parameters – the following for each completion: · Completion start measured depth · Completion end measured depth · Completion start true depth · Completion end true depth The Cinco (2) / Martin-Bronz model is similar to the Cinco / Martin - Bronz model. The difference between the two models is that the Cinco (2) / Martin-Bronz model also considers the anisotropy in the reservoir. The vertical permeability entered in the Deviation and Partial Penetration screen is used to calculate the Deviation Skin.
2.6.5 Sand Control Options PROSPER offers different sand control options that can be selected under | Options | Options | Well completion | Sand Control:
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The following sand control options are available: - Gravel Pack, - Pre-Packed screen, - Wire-wrapped screen and - Slotted Liner
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2.6.5.1 Gravel Packed Completion PROSPER can model openhole gravel pack as well as cased hole gravel pack. PROSPER models gravel packed completions as a concentric cylinder having a User specified permeability connected to the well bore via perforations of specified diameter. By sensitising on perforation spacing and diameter, the effect of pressure drop due to flow concentration on well performance can be investigated. Likewise, the effect of varying gravel length (i.e. the thickness of gravel between the OD of the screen and the ID of the original open hole) on skin can be evaluated. A sample gravel pack data input screen for a cased hole is shown below:
The following data input is required: Gravel pack permeability (Enter the in-site permeability for the gravel) Perforation diameter (Diameter of perforation tunnel) Shots per foot (Shot Density Gravel pack length (Distance from the screen O.D. to the sandface) (The perforation interval for the sand control · Perforation interval options is used for calculating the flow velocities only and is the measured depth not the TVD) · · · ·
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· Perforation efficiency effective) · Beta (Turbulence) or Entered) · Method Ü
(Proportion of perforations that are open and (Select if the Non-Darcy factor is Calculated (Single Phase or Multiphase)
The Multi Phase Method consists of using phase-weighted fluid properties during gravel pack pressure drop calculations. This option is only active in case of Oil fluid type. The Single Phase method is the classic method which utilises the main fluid type properties (i.e. Oil properties in case of oil fluid).
On the right side of the screen a table shows typical permeability data for different types of gravels. The pressure drop across a gravel pack is computed using a summation of a Darcy and a non-Darcy component. For a cased oil well, the pressure drop due to the gravel pack (dPgravel) is calculated using the Jones IPR equation:
dPGRAVELPACK = a Q 2 + b Q Where: a = The non-Darcy term, Q = The total liquid rate and b = The Darcy term Intermediate calculations are required prior to computing the dPgravel value and consider the following variables: Kg = Gravel Pack Permeability β = 1.47E7/Kg^0.55 PerfDi = Perforation Diameter SPF = Shots per ft PRFINT = Perforation Interval AOTF µo
= Area Open To Flow = π (PerfDi/24)2SPF*PRFINT = Oil Viscosity in cp
Bo
= oil FVF
ρo
= Oil Density
L
= Gravel pack length
The Darcy (B-term) and the non-Darcy (A-term) are calculated a-Term = 9.08E-13* β *Bo2* ρo *L/12/AOTF2
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b-term = µ o *Bo*L/12/(1.127E-3*Kg*AOTF). This dP may then be transformed into skin using an appropriate relationship. The main geometric parameters are shown on the following sketch:
Skin can be calculated using one of the methods described in Section 7.3 or directly entered. Note that partial completion skin is included in the total well skin, and is not affected by adjusting the gravel pack completion parameters. The total well skin as measured by a well test prior to gravel packing should be entered. Click Calculate when finished entering data and an IPR plot similar to that below will be presented (the plotting of the individual dP components can be chosen from the Variables menu in the plot window):
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The contribution of the gravel pack to the total skin pressure drop can be readily seen on the IPR plot. The value of skin posted on the IPR plot does not include the gravel pack skin. Click Results on the IPR plot screen to display the breakdown of dP's resulting from each completion element. Sensitivities can be calculated on factors such as gravel pack thickness, shots per foot etc. to evaluate the effectiveness of gravel pack designs. Gravel packed completions are also available in the Multi-layer IPR model. The PROSPER gravel pack model allows for non-Darcy (i.e. dP proportional to rate squared) effects within the gravel pack and the resulting rate dependent skin. Lift curves for gravel packed wells generated using PROSPER can be calculated from the sandface, through the completion, and back to the production manifold. This more correctly models the IPR as compared to simply imposing an additional skin to allow for the gravel pack pressure loss as is done in many reservoir simulators. Ü
Gravel packs can be combined with the Hydraulically Fractured Well IPR to model ‘Frac-Pack’ completions.
A summary of the main IPR equations is given in Appendix B.
2.6.5.2 Pre-Packed Screen completion Pre-packed screens can be modeled in PROSPER. For this, the option "Pre-packed Screen" should first be selected under | Options | Options: PROSPER Manual
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The description of the sand control type is made under | System | Inflow Performance | Input Data | Sand Control:
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The following inputs are required to describe a pre-packed screen completion: - Screen inner radius, - Screen outer radius, - Screen inner and outer Permeability, - Screen inner and outer Turbulence. The IPR curve is generated with | Calculate:
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In order to visualize the rate-dependent skin associated with the pre-packed screen, one selects | Results and all the calculation results are listed in detail:
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2.6.5.3 Wire-Wrapped Screen Completion Wire wrapped screens can be modeled in PROSPER. For this, the option "Wire Wrapped Screen" should first be selected under | Options | Options:
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The description of the sand control type is made under | System | Inflow Performance | Input Data | Sand Control:
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The following inputs are required to describe a pre-packed screen completion: - Screen outer radius, - Screen outside Permeability, - Screen outside Turbulence. The IPR curve is generated with | Calculate:
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In order to visualize the rate-dependent skin associated with the wire packed screen, one selects | Results and all the calculation results are listed in detail:
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2.6.5.4 Slotted Liner Completion PROSPER can model wells completed with slotted liners. To model a slotted liner completion with PROSPER, one first need to activate this feature under | Options | Options | Sand Control: Slotted Liner:
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The description of the sand control type is made under | System | Inflow Performance | Input Data | Sand Control:
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The input data required to model the slotted line completion are: - Liner Inner Radius, - Liner Outer Radius, - Slot height - Slot width - Slot density - Screen Outer Radius (optional) - Outer Permeability and - Outside turbulence (optional). The IPR curve is generated with | Calculate:
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In order to visualize the rate-dependent skin associated with the slotted liner completion, one selects | Results and all the calculation results are listed in detail:
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2.6.6 Other IPR-related features
2.6.6.1 Gravel Pack Completion Velocities In the IPR results (accessible from the Plot view, Results menu) the velocity at the Casing (Vc) is available, along with the Gravel Pack A and B factors:
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The gravel pack velocities have been incorporated in Version 6 of the IPM Suite of tools. Vc is the velocity of the fluid at the entry point of the casing. It is calculated by dividing the flow rate of the fluid with the area of flow at the casing. These velocity calculations were implemented at the request of clients who require these velocities for gravel pack design.
2.6.7 Viscosity Modelling This screen is activated only when the fluid option Non-Newtonian fluid is selected.
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Enter in this screen the required parameters: Wellbore radius
Radius of the hole, corresponding to the drill bit size
Drainage Area
Area of the drainage region
Reservoir Thickness
Vertical thickness of producing interval
Reservoir porosity
Porosity
Connate Saturation
Connate water saturation
Water
These parameters are used to determine an equivalent flowing radius that will be used by the program to estimate the pressure drop due to the friction in the reservoir. The dP friction will take in account of the fluid apparent viscosity (which is velocity dependent) calculated by the Non-Newtonian viscosity model.
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2.6.8 Compaction Permeability Reduction The Compaction Permeability Reduction option is an analytical model to estimate the change of Reservoir Permeability due to reservoir compaction effects. The correction is carried out by means of a correction factor that will be then applied to the permeability
where: Corr = Permeability Correction Factor (Multiplier) Cf = Rock Compressibility PR = Current Reservoir Pressure PRi = Initial Reservoir Pressure N = Compaction Model Exponent This option can be enabled in the main IPR section:
The option will activate a new TAB screen in the Input Data section where the basic model inputs are required:
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The input data required by the model are: Initial Pressure
Reservoir
Reservoir Compressibility Compaction Exponent
Initial reservoir pressure Reservoir Rock Compressibility
Model
Exponent (see definition above)
2.6.9 Injection Wells Irrespective of the inflow model used, Injection well IPR calculations are complicated by a number of factors as compared to producers: · Injected fluid temperature at the sandface is a function of surface temperature, injection rate history and well configuration. · Relative permeability to injected fluid is required. · Injectivity changes with time as the fluid bank is pushed back away from the well. · Fracturing (mechanical or thermally induced) often occurs. Adequate results for injection well IPR can be obtained by reducing the reservoir temperature on the IPR input screen to near the estimated sandface injection PROSPER Manual
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temperature. The Enthalpy Balance temperature model can be used to estimate injected fluid temperatures. PROSPER uses the reservoir pressure and temperature to estimate fluid PVT properties in IPR calculations. Most of the IPR pressure drop occurs near to the well. With this in mind, use an effective permeability appropriate to the given conditions. For empirical inflow models such as Vogel and Multi-Rate methods, the effect of cold injection fluid viscosity is accounted for in the pressure points. Changing the reservoir temperature will have no effect in these cases.
2.6.10 SkinAide The SkinAide inflow method has been developed by Elf Aquamarine and acknowledgement is given for its inclusion in PROSPER. The following description is based on information provided by Elf. 2.6.10.1SkinAide Theoretical Background Consider the case of a partially penetrating, deviated well, cased and perforated and equipped with a gravel pack. The total pressure drop around such a well corresponds to the pressure difference between: - an equipotential surface at the external limit of the reservoir drainage area, and - another equipotential surface corresponding to the screen. This total pressure drop is due to a number of features. Moving downstream from the external limit of the drainage area towards the well: - the position of the producing interval with respect to the reservoir geometry (due to partial penetration and deviation). - the damaged zone. - interference between the different perforations. - the crushed zone surrounding the perforation tunnels. - gravel in the perforation tunnels. - gravel in the annulus between the screen and the casing. Pressure drops between equipotential surfaces can be added to one another, and the conceptual model corresponds to an attempt to simplify the problem by finding equipotential surfaces.
2.6.10.1.1 Position of the producing interval with respect to reservoir geometry The pressure drop due to the position of the producing interval with respect to the reservoir geometry can be considered to be independent of the pressure drop surrounding the well completion in so far as one can imagine an equipotential cylindrical © 1990-2011 Petroleum Experts Limited
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surface with, say, a 2 m radius, separating the two regions.
This pressure drop is calculated in SkinAide using a reservoir engineering correlation.
2.6.10.1.2 Interference between perforations and the damaged zone Moving downstream, the next feature encountered is the interference between perforations and the damaged zone. If the perforation tunnel emerges from the damaged zone, the damaged zone has much less influence than if the perforation remains entirely within the damaged zone.
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calculated using the Karakas and Tariq correlation.
2.6.10.1.3 The Crushed Zone The downstream limit of the previous feature is the crushed zone. The outside surface of the crushed zone, and the inner surface of the perforation tunnel are both assumed to be equipotentials. As a result flow in both the crushed-only and the crushed-and-damaged zones is radial.
Pressure drops in the crushed zone can be calculated analytically.
2.6.10.1.4 Perforation tunnel which penetrates the formation The next feature downstream is flow in that part of the perforation tunnel which penetrates the formation. We use the flux into the tunnel previously calculated for radial flow in the crushed zone to calculate the flow profile along the tunnel :
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This situation can be solved analytically.
2.6.10.1.5 Perforation tunnel through the casing and cement Moving yet further downstream, two equipotentials can be drawn, one at the external surface of the cement, the other on the inside of the casing:
This linear flow can be solved analytically.
2.6.10.1.6 Annulus between Casing and Screen The last feature is the region between the equipotential at the opening of the perforation tunnel in the casing, and the screen.
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An approximate analytical solution has been found for flow in this region. 2.6.10.1.7 Hemispherical Flow Model The conventional linear perforation model assumes that the surface of the perforation tunnel is an equipotential surface. This assumption breaks down when permeability of gravel in the tunnel becomes sufficiently low. When permeability in the tunnel becomes sufficiently small, flow in the reservoir approaches hemispherical flow towards the perforation mouth.
Flow takes place - in the reservoir beyond the crushed and the damaged zones - in the damaged zone - in the crushed-and-damaged zone - in the perforation tunnel itself. Analytical solutions to hemispherical flow have been developed to represent this model, which can be considered to be an upper bound to the conventional linear perforation model.
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2.6.10.2Using SkinAide When the SkinAide IPR model is selected, the following IPR Input screen is presented:
Select the required options for the Flow and Skin models plus Perforation Data. The options are listed below:
2.6.10.2.1 Flow Model Steady State - corresponds to a constant flux at the outer reservoir boundary. The inflow at the external boundary is equal to the well flow rate. This boundary condition corresponds to pressure maintenance by natural (aquifer influx, gas cap drive) or artificial (gas or water injection). The steady state productivity equation is: Semi Steady State - corresponds to no-flow at the outer reservoir boundary. This boundary condition corresponds to reservoir depletion with no pressure maintenance. The radial flow Productivity Index equation for semi-steady state is: These equations differ only in the constant 3/4 vs 1/2 for steady state flow. These radial flow equations can be generalised for other drainage geometries. ·
Ü
Pe, the static reservoir pressure is the average pressure in the well drainage area, not the pressure at the external boundary. Pe is used in the Productivity Index equation: The reservoir pressure should be entered at the same reference datum as the intake node depth.
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2.6.10.2.2 Skin Model Linear Flow - Skin pressure drop is calculated assuming that flow is predominantly linear towards the well. This is the normal situation for a well completed across most of the reservoir. · Hemispherical Flow - Skin pressure drop is calculated assuming a hemispherical flow geometry. This situation occurs for single perforations or wells having extreme partial completion effects. · Flow Giving Minimum dP - Skin pressure drop is calculated assuming flow is always along the path of lowest resistance. (i.e. between linear and hemispherical flow)
2.6.10.2.3 Perforation Data · In-Situ Geometry Entered - The dimension of the actual perforations in the reservoir are entered. · API Test Data Edition 4 - API perforation gun data are entered and SkinAide estimates the downhole perforation geometry. · API Test Data Edition 5 - API perforation gun data are entered and SkinAide estimates the downhole perforation geometry. This option utilises more recently defined gun test specifications. Having selected the required options, SkinAide requires data entry in the following categories: · Geometry (Reservoir dimensions) · Petrophysics (Reservoir permeability etc.) · Damaged Zone (Damaged zone properties) · Cased Hole (casing dimensions) · Crushed Zone (Crushed zone properties) · Perforations (Gun and perforation geometry) · Gravel Pack (Only for Gravel Packed wells)
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The data required can vary according to the options selected. Click each data entry button in turn and enter the data as follows:
2.6.10.2.4 Geometry · Reservoir Thickness - Enter the thickness normal to the bedding plane in dipping reservoirs. When thin shales are distributed throughout a heterogeneous reservoir, use the net sand thickness.
· Completed Interval - Enter the perforated interval as measured along the wellbore.
· Distance to Top of Completion - This parameter affects partial completion skin and is measured along the wellbore. If gross sand thickness is used for reservoir thickness, enter the actual distance to the top perforation (dimension h1 in the above sketch). When using net sand, restrict the distance to net sand intervals. · Drainage Area - Area drained by the subject well · Dietz Shape Factor - Allows for drainage area shape and well placement.
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· Hole Diameter - Open hole drilled diameter. Use bit size or caliper measured size where applicable. Perforation length, damage depth are measured beyond the hole diameter. · Deviation - Average angle between the well axis and vertical.
2.6.10.2.5 Petrophysics Horizontal Permeability - Reservoir permeability measured parallel to the cap rock (along the bedding plane).
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·
Vertical Permeability - Reservoir permeability measured perpendicular to the horizontal permeability in the vicinity of the completed interval. Used to determine anisotropy ratio near the perforations. Values can be taken from core analysis.
·
Vertical Permeability for Geometrical Skin - Reservoir permeability for the bulk reservoir measured perpendicular to the horizontal permeability. Determines the anisotropy ratio between the completed interval and the remainder of the reservoir.
·
Porosity - Used in the high velocity flow coefficient correlation: Where: k Reservoir horizontal permeability f Reservoir porosity a,b,c Constants Correlations are used to estimate the values used in the high velocity flow equation. Field specific correlations can be prepared from well test analysis.
·
Turbulence coefficient a - multiplier for the overall turbulence coefficient. Dimensions are reciprocal distance.
·
Permeability exponent b - Permeability raised to this power. Default is -1.33. Note, the exponent value entered corresponds to permeability in millidarcies regardless of the current unit set.
·
Porosity exponent c - Porosity raised to this power. Default is 0.0. Note the exponent value assumes the porosity is a fraction, regardless of the current unit set.
High velocity flow pressure drops arise from acceleration and deceleration of reservoir fluids as they pass through pore throats as in the following diagram:
2.6.10.2.6 Damaged Zone The damaged zone is modelled as an annulus surrounding the wellbore in which permeability and porosity have been impaired during the drilling and completion process. The depth of damage is measured beyond the drilled hole.
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In anisotropic reservoirs, formation damage is deeper in the low permeability direction than the high permeability. An elliptic damaged zone forms in such cases. SkinAide assumes a circular damaged zone irrespective of reservoir anisotropy.
·
Damaged Zone Thickness - Since damaged zone skin is controlled by the ratio of perforation tunnel length to damaged zone depth, enter a damage zone depth that respects this relationship.
·
Damaged Zone Permeability - Determines the ratio of damaged zone to reservoir permeability. Estimating the true value is not straightforward, however, the undamaged reservoir permeability could be used as a starting point.
·
Damaged Zone Porosity - Porosity to be used in the high velocity flow coefficient correlation.
2.6.10.2.7 Cased Hole The casing dimensions are used to correct the API perforation length for field conditions. The casing I.D. is calculated from the O.D. and casing weight. ·
External Casing Diameter - Enter nominal casing diameter opposite the completed interval.
·
Casing Weight - Enter nominal casing weight per unit length opposite the completed interval.
2.6.10.2.8 Crushed Zone Shaped charge perforating creates a cavity filled by charge debris and surrounded by a zone of reservoir rock that has been altered by the high pressure / high temperature jet. Charge debris is removed by perforation washing or underbalanced perforating - the crushed zone remains. SkinAide recognises separate properties for the crushed zone in the undisturbed reservoir and damaged zone.
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Most of the high velocity flow pressure loss occurs in the crushed zone and is added to the loss in the reservoir. Note that if a zero crushed zone thickness is entered, no high flow velocity pressure drops are calculated. ·
Crushed Zone Thickness - Thickness of perforation altered zone. The default value is 0.5 inches.
·
Crushed Zone Permeability - Reduced permeability for crushed zone within the virgin reservoir.
·
Crushed Zone Porosity - Porosity in the crushed zone for estimation of high pressure flow losses.
·
Crushed + Damaged Zone Permeability - Permeability for the crushed zone within the damaged zone.
·
Crushed + Damaged Zone Porosity - Porosity for the crushed zone within the damaged zone. Permeability in the crushed and damaged zone is introduced by the ratio: Rcrushed and damaged = Crushed and damaged zone (horizontal) permeability / undisturbed formation (horizontal) permeability. The same anisotropy ratio opposite the completion interval as applies to the undisturbed formation is used for the crushed and damaged zone permeability. It is suggested that the crushed and damaged zone permeability ratio should be the product: Rcrushed and damaged = Rdamaged·Rcrushed only. Where the ratio for the damaged zone: Rdamaged = damaged (horizontal) permeability / undisturbed formation
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permeability
and the crushed-only zone: Rcrushed only = only crushed zone (horizontal) permeability / undisturbed formation (horizontal) permeability.
2.6.10.2.9 Perforations The perforation data input depends on the option selected. If In-Situ Geometry is selected, the actual perforation sizes are required. Alternatively, API test data can be entered for a particular gun, and SkinAide will estimate the perforation geometry considering completion and reservoir variables such as compressive strength and casing size. Common Perforation Parameters ·
Perforation Efficiency - The number of producing perforations is the product of perforation efficiency, shot density and the length of the completed interval. Perforation efficiency is used to account for ineffective perforations such as those shot into shaly beds. If gross sand is used to define reservoir geometry, the maximum perforation efficiency should be the ratio of net/gross reservoir sand. If net sand is used, the perforation efficiency does not need to be further modified.
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·
Shot Density - Nominal shots per foot for the selected perforating gun.
·
Gun Phasing - Angle between two adjacent perforating charges. interference between perforation tunnels.
·
Angle Between Vertical Plane and Perforations - For anisotropic reservoirs, the angle between the perforation tunnels and the direction of maximum permeability influences productivity. When 0° or 180° guns are selected, perforations are all aligned with the low side of the hole. For other gun phasings, SkinAide assumes an angle of 45°.
Affects
In-Situ Geometry Entered ·
Tunnel Length - Length of effective perforation in the reservoir formation i.e. beyond the cement sheath.
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·
Tunnel Diameter - Diameter of effective perforation in the reservoir formation.
·
Cavity Entrance Diameter - Not active - use Tunnel Diameter. SkinAide presently uses a cylindrical model for perforations. Future versions will allow a cone-shaped perforation geometry.
·
Cavity Tip Diameter - Not active - use Tunnel Diameter. SkinAide presently uses a cylindrical model for perforations. Future versions will allow a cone-shaped perforation geometry.
API Test DataThe correction from test data to In-Situ conditions is influenced by the API test series selected. The form of data input is identical for both options. ·
API RP 43/2 Total Target Penetration - Length of perforation in Berea sandstone target. If RP 43/2 data is unavailable, use 2/3 of API RP43/1 cement target TTP.
·
API RP 43/1 Entry Hole Diameter - Entry hole diameter for steel / cement target test. Note that the steel quality changes between Editions 4 and 5 of the API test specifications. Ensure the relevant data is entered.
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·
Gun diameter - Gun diameter is used to correct API perforation test results for stand-off.
·
Reservoir Uniaxial Compressive Strength - Compressive strength is used to calculate in-situ perforation dimensions. Typical values of reservoir uniaxial compressive strength are given in the following table:
Lithology
Reservoir
Uniaxial
Compressive (psi)
Strength (bar)
Loose sand
150
10
Sand which crumbles by hand
750
50
Sandstone from which sand grains can be peeled by hand
1500
100
Well cemented sandstone
3750
250
Well cemented limestone
3750
250
· ·
·
Rock Density - Enter apparent In-Situ rock density as measured by a density log, not the density of the minerals (e.g. Quartz) that comprise the formation grains. Casing Elastic Limit - Used for correction of API data to In-situ perforation dimensions. The elastic limit in thousands of psi corresponds to the pipe steel quality. e.g. N80 casing has an elastic limit stress of 80,000 psi. Reservoir Stress - Used for correction of API data to In-situ perforation dimensions. Stress is assumed to be Isotropic. Generally the minimum effective stress (frac gradient) is suitable.
Gravel Packs in SkinAideWhen the Gravel Pack option has been selected, additional data entry is required to describe the pack geometry and properties. Separate gravel properties can be entered for the annular gravel pack and the sand in the perforation tunnels. This allows mixing of formation and pack sand to be simulated.
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·
Screen Outside Diameter - The space between the screen O.D. and the drilled hole diameter is occupied by gravel.
·
Annulus Gravel Permeability - Permeability of gravel in the space between the screen and the open hole. Gravel size is specified in terms of mesh size. e.g. 20/40 mesh gravel will pass a sieve with 1/20 inch holes, but not pass a 1/40 inch sieve. Average laboratory measured permeability values for various gravel sizes are given in the following table:
Gravel
Mesh
Type Ottawa Sand
Carbolite
Isopac
Lab Permeability (Darcies)
12/20
500
20/40
150
30/50
90
40/60
60
50/70
30
20/40
350
16/20
500
20/40
110
·
Annulus Gravel Porosity - Used in calculation of high velocity flow coefficient in the gravel pack.
·
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·
Tunnel Gravel Porosity - Used to reduce the porosity of sand in the perforation tunnels.
The inflow and skin pressure drop are computed by clicking the Calculate button once all the relevant input data have been entered and Plot to display the results. To evaluate the contribution of individual completion components in the inflow performance, click Variables and select the parameters to display as in the following screen example:
Select the required variables by clicking their check boxes. Click Done to display the results:
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Skin Components The conceptual models used to calculate the total skin factor include : - a contribution due to the position of the producing interval with respect to reservoir geometry, called geometric skin Sgeometric - contributions due to pressure losses close to the actual wellbore, beginning with the pressure loss due to the damaged zone and ending with pressure loss in the casing/screen annulus for gravel packed wells. This contribution to the total skin is called the completion skin Scompletion. The total skin is the sum of the two components Stotal =Sgeometric + Scompletion The contribution Scompletion to the total skin is particularly convenient when using reservoir engineering equations. However Scompletion does not necessarily reflect the quality of the completion itself. Indeed, imagine two wells with identical completions, producing reservoirs with identical properties, the thickness of one reservoir is double that of the other:
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Scompletion = a k h DPcompletion / ( Q m B ) Since DPcompletion is identical but reservoir thickness h differs by a factor 2, applying the above relation leads to values of Scompletion, which differ, by a factor 2. Mechanical skins are defined so as to reflect the quality of well completion. In the formula for mechanical skins, the vertical reservoir thickness h is replaced by the length of the producing interval (measured along the wellbore) hp : Smechanical = a k hp DPskin / ( Q m B ) where, for oil wells, a k hp
SI depends on units 2p permeability m2 length of the completed interval m
DPskin DPreal well - DPidealized well Q flowrate (standard conditions) m viscosity (reservoir conditions) B fluid formation volume factor
US 7.07 10-3 mD ft
French 0.0536 mD m
Pa
psi
bar
m3/s Pa.s v/v
bpd cP v/v
m3/d cP v/v
Total and mechanical skins are related by the simple formula : Smechanical / hp = Scompletion / h
2.6.11 SPOT: Shell Perforating Optimisation Tool The SPOT inflow method has been developed by Shell and permission is given for its inclusion in PROSPER. The following description is based on information provided by Shell. 2.6.11.1Introduction to SPOT SPOT (Shell Perforating Optimisation Tool) is a module that enables engineers to predict and compare perforation charge performance, assisting selection of the optimal perforating gun. It should be highlighted that SPOT is not a perforating charge sales tool; the purpose of SPOT is to allow Users to easily assess and compare performance of different completion techniques. Perforating charge performance is calculated using: ·
Charge properties
·
Reservoir rock properties (field average or log scale properties)
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Fluid properties
·
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SPOT can be used to analyze different completion types including; openhole, conventional case and perforated, open hole perforated, and casing conveyed perforated. Thus, a User can identify if perforating is the correct technique for their application, and if not, pursue alternative technologies, including, but not limited to barefoot completions, stimulation, underbalanced drilling and propellants. SPOT is a powerful model that gives the User the ability to directly compare perforation charge performance in reservoir rock on a log scale. It takes into account perforation depth of penetration, entrance hole diameter, shot density and drilling mud invasion. SPOT is intended to demonstrate that perforation charges often don’t pass the mudinvaded zone and that correct mud design is vital in these cases (particularly in low permeability reservoirs). In PROSPER, the output from SPOT, an Inflow Performance Relationship (IPR) curve, can be directly combined with any Vertical Lift Performance (VLP) correlation to predict the well performance under various operating conditions: well head flowing pressure, water cut, GOR and so on.. Here is a list of the peculiar acronyms used in the SPOT inflow module along with their meaning: API
American Petroleum Institute
AOF
Absolute Open Flow
CBL
Cement Bond Log
CFD
Computational Fluid Dynamics
EoH
Entrance Hole Diameter
DoP
Depth of Penetration
FDC
Formation Density Compensated
GUI
Graphical User Interface
IPR
Inflow Performance Relationship
NWEVS
Near Wellbore Effective Vertical Stress
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RP
Recommended practice like API RP XX
OB
OverBalanced
SPOT
Shell Perforation Optimisation Tool
TWC
Thick Walled Cylinder
UCS
Unconfined Compressive Strength
WIQI
Well Inflow Quality Index
2.6.11.2Gun System databases The gun database contains API 19-B1 and API RP 43 Section I Data for perforating guns available from: · Baker Hughes Incorporated (Baker) · Schlumberger (SLB) · Halliburton/ Jet Research Centre (Hall/JRC) · Dynawell (DYNA) · Innicor Subsurface Technologies (INNICOR) · Owen Oil Tools (Owen) · Explosivos Technologicos Argentinos (ETA) · GEODynamics (GEODynamics) · Titan (TITAN) Companies were provided with an opportunity to adjust/ update data in the SPOT Gun Database. It is recommended that Users cross check all critical information with the appropriate perforating manufacturer/ service company before a gun type/ completion method is selected. Sections I to IV of API 19-B are summarised below: PROSPER Manual
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· Section I - firing a fully-loaded gun section under ambient conditions into a standard casing and cement target; · Section II - firing a single charge under pressurized conditions into a stressed rock sample; · Section III - firing a single charge into a metal target at elevated temperature; · Section IV - firing a single charge into a stressed rock sample under simulated wellbore and reservoir conditions, then measuring the flow performance of the perforated sample relative to its performance prior to shooting; · Section V2 - measuring the amount of debris retained within a fired fully-loaded gun section in order to calculate how much debris will be introduced into the wellbore per foot of gun; A report containing lists of all data can be automatically generated in SPOT by using “Data” followed by “Reporting” selected from the Toolbar. It should be noted that API RP43 preceded API RP19B. The American Petroleum Institute (API) Perforating Subcommittee adopted API RP19B during November of 2000, and state that API 19B “is the only document that API recognizes as valid in this program.” As API 19B data is not available for all gun systems, API RP43 data has also been included in the database (data sources are clearly marked). Although API RP43 is not officially valid, Section 1 testing for both API RP43 and API 19B is based on concrete targets. As concrete is not representative of reservoir rock, API 19-B and API-RP 43 Section 1 data is converted to downhole conditions in SPOT using Shell proprietary correlations (based on laboratory research). Although these correlations should provide a reasonable estimate of perforation characteristics in reservoir rock under downhole conditions, a better estimate of perforation performance can be obtained by conducting reservoir specific Section II (firing a single charge under pressurized conditions into a stressed rock sample) and/or Section IV tests (firing a single charge into a stressed rock sample under simulated wellbore and reservoir conditions, then measuring the flow performance of the perforated sample relative to its performance prior to shooting). If Section II or Section IV data is available, it can be entered into the SPOT “Vendor Database” under the Section II/Section IV Data heading. If the concrete strength during the API RP 19B or API RP43 test is not recorded in the Gun Database, in accordance with the minimum allowable strength specified in API RP 19B, a briquette strength of 5000psi is assumed in SPOT calculations. 1. API Recommended Practice 19-B, “Recommended Practice for the Evaluation of Well Perforators”, 1st Edition, 28 Sep 2001
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2. To be introduced in the next revision of RP 19-B, a draft of which is with API for review at the time of writing.
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All the guns available in SPOT as well as corresponding information is displayed here. Note that Normalised gun data displays Section 1 results that have been converted to 5000psi pressure (rather than ambient conditions). Companies were provided with an opportunity to adjust/ update the data in the SPOT Gun Database. It is recommended that the User cross checks critical information with the appropriate perforating manufacturer/ service company before a gun type/ completion method is selected. It should be noted that API RP43 preceded API RP19B. The American Petroleum Institute (API) Perforating Subcommittee adopted API RP19B during November of 2000, and state that API 19B “is the only document that API recognizes as valid in this program.” As API 19B data is not available for all gun systems, API RP43 data has also been included in the database (data sources are clearly marked). Although API RP43 is not officially valid, Section 1 testing for both API RP43 and API 19B is based on concrete targets. As concrete is not representative of rock, API 19-B and API-RP 43 Section 1 data is converted to downhole conditions in SPOT using Shell proprietary correlations (based on laboratory research). Although these correlations should provide a reasonable estimate of perforation characteristics in reservoir rock under downhole conditions, a better estimate of perforation performance can be obtained by conducting reservoir specific Section II (firing a single charge under pressurized conditions into a stressed rock sample) and/or Section IV tests (firing a single charge into a stressed rock sample under simulated wellbore and reservoir conditions, then measuring the flow performance of the perforated sample relative to its performance prior to shooting). If Section II or Section IV data is available, it can be entered into the SPOT under the Section II/Section IV Data heading. The following data must be entered under the Section II/Section IV Data heading: · Basic gun information e.g. gun type, gun size and vendor name · Deep Penetrating/ Big Hole: the type of gun must be selected and if the gun is classified as a deep penetrating or big hole charge. This information should be available in the Gun Database. Generally, a deep penetrating gun will have an entrance hole less than or equal to 0.5in. · Depth of penetration: the perforating depth of penetration measured from the inside of the casing or tubing to the end of the perforation tunnel (Reference: API RP19B, “Recommended Practice for Evaluation of Well Perforators”, 2001). · Entrance hole diameter: the diameter of the hole through the casing · Test sample compressive rock strength (UCS) · Effective stress: the net effective stress applied on the sample in a Section IV test or 3000psi for a Section II test (Reference: API RP19B, “Recommended Practice for Evaluation of Well Perforators”, 2001). If a pseudo Section II test was conducted at atmospheric conditions the effective stress would be zero. · Casing material: Select between J55, L80, P105 or P110. If a different material was used in the test, pick the material with the closest hardness. i.e.:
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Material
J55
L80
P105
P110
Brinell Hardness
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230
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· Fluid fill type: This is the fluid fill in the pore spaces of the rock sample. According to API RP19B, “Recommended Practice for Evaluation of Well Perforators”, 2001, the pore fluid should be sodium chloride brine solution (3% by weight). This function allows you to conduct a pseudo Section II or Section IV test with gas filled core to represent a gas reservoir and input the result in SPOT. Note that the well bore fluid is always assumed to be liquid. · Standoff during test: This is the distance from the outside of the perforating charge case to the inside of the casing. According to API RP19B, “Recommended Practice for Evaluation of Well Perforators”, 2001, the standoff should normally be 0.5in. · Core Sample Size: Select between 4in and 7in core sample used in the Section II or Section IV test. If neither a 4in or 7in core sample was used in the laboratory tests, the User should select the core size closest to these bounds. This information is used in the Synthetic Effective stress Correlation selected on the Options screen). It should be highlighted that flow data obtained from Section IV test is not used in the SPOT inflow performance calculation. The Core Flow Efficiency (CFE) ratio can however be used as a qualitative check and for charge/charge comparisons. The User also has the ability to enter additional gun systems in the Gun Database by clicking the "Add" button.. Gun selection from the Vendor Database can be made according to: · Vendor · The type of gun i.e. wireline, tubing conveyed · Gun OD · Clearances: o Enter the minimum restriction. o Restriction Tolerance. o Click "Update" which will only display guns with an OD less than the minimum restriction minus the tolerance. o Click "Clear" to remove the above filtering.
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2.6.11.2.1 Gun
This dialog is used to examine a single gun from the guns database. It is displayed in different situations:Editing/entering a new gun in the database: If you have the API 19B or 43 test for a new gun which is not in the default database, the gun can be added by the user. In this case the dialog is used to enter or edit the information from the test sheet. Viewing details for a selected gun: © 1990-2011 Petroleum Experts Limited
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This dialog is also used to display the details of the gun that the user has selected for the SPOT calculations. Click the "Select Gun from Database" button to pick a gun from the guns database. In this case most of the fields are disabled as they are read only. The only two fields in the "Gun Details" that are enabled are Shot Density and Gun Phasing. These two values are specified in the API 19B and 43 test. However some guns can be configured to different values to those used in the test. In this case we allow the user to modify them from the values in the test. Warning : although we allow these values to be modified this is strictly incorrect as the shot density and phasing have an effect on the Lp. The section 2/4 data is also enabled as this may be modified by the user. See the Gun Database help for specific information on the data.
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2.6.11.2.2 Spot Perforation Calculations
This dialog allows the user to select a gun from the PROSPER gun database and correct the test Lp and EHD to in-situ conditions using the Shell SPOT corrections. These are the same calculations as used in the full SPOT IPR but this calculation is for a single set of conditions e.g. UCS, permeability. The Lp and EHD can then be transferred to the PROSPER IPR data and used in calculation of skin. Input Data: This is a description of the in-situ data required by the SPOT Lp and EHD correction.
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Lp Correlation Type ·
“API19B Section 1- API 19B Section II or IV Conventional Correlations”- these correlations assume that effective stress applied in a Section II or Section IV test setup reaches the centre of the sample. The correlation should also be used for a Section 1 test (no effective stress applied)
·
“API 19B Section 1- API 19B Section II or IV Synthetic Rock Correlations”- these correlations are based on Shell laboratory tests in which it is believed that effective stress applied in a Section II or Section IV type test setup does not reach the centre of the core sample. These adjustments are made to reflect the fact that the perforation depth of penetration under effective stress measured at surface in conventional Section II and IV setups is not the perforation depth that would be expected downhole under the same effective stress condition. It should be highlighted that effective stress applied using a triaxial test approach is believed to be valid and as such the “API 19B Section 1- API 19B Section 2 conventional correlations” option should be selected.
It should be highlighted that effective stress applied using a triaxial test approach is believed to be valid and as such the “API 19B Section 1- API 19B Section 2 conventional correlations” option should be selected. Casing OD Casing Weight Casing Grade API 19B/43 tests are performed through a casing defined in the test data. So if if a much thicker casing is used then it will decrease the Lp as more of the gun energy is lost perforating the casing. Or if a thinner casing is used then the Lp will be higher. These data should refer to the casing at the depth of the perforation. If a different casing grade was used in the test, pick the material with the closest hardness. i.e.: Material J55 L80 P105 P110 Mean Brinell Hardness 180 230 275 320 Layer Fluid - For producers this is fixed by the type of the producer. For injectors this should be set to the fluid in the rock that is being perforated. Rock Type - The rock type to be used in the perforation calculation must be selected. (carbonate or sandstone). This will affect the perforation depth of penetration calculation. It should be highlighted that SPOT does not take karsts and fractures into account when modeling inflow performance of carbonates. This may result in unrealistic flow results. Use Downhole Standoff - Select "Yes" if you wish to enter a gun standoff. Otherwise select "No" in which case the gun is assumed to be centralized. Downhole Standoff - If "Use Downhole Standoff" is set to "Yes" enter the value to be used. PROSPER Manual
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Well Radius - Wellbore hole radius Effective Stress Data: In-situ effective stress is one of the key numbers in the correction of Lp and EHD in the SPOT algorithm. This section of the dialog allows entry of data to calculate the effective stress or to enter the value directly. Mean Sea Level wrt Origin, Sea Bed Depth wrt Origin - Used to calculate the effect of sea on in-situ effective stress (enter zero if on-shore). Depth - Measured depth of the perforation. Overburden Pressure Gradient - This pressure gradient is used to calculate the overburden pressure and subsequently the Near Wellbore Effective Vertical Stress (NWEVS). The NWEVS is used in perforation depth of penetration calculations. A common overburden pressure gradient (i.e.lithostatic pressure gradient) is 1psi/ft. Reservoir Pressure - Average current reservoir pressure. Enter Effective Stress, Effective Stress - To enter the value of effective stress directly, select "Enter Effective Stress" and enter the "Effective Stress". Gun Data: This section of the dialog shows the data relating to the selected gun. See Guns Database for information on this data. Click the "Select Gun" button to pick a gun from the guns database. Section 2/4 Gun Data: If section 2 or 4 gun test data is available, tick this box and enter the data. See Guns Database for information on this data. Calculated Data: Click the "Calculate" button to calculate the actual Lp and EHD. If you wish to use these values, click the "Transfer" button to copy these calculated values to the IPR data. Note that the calculated casing ID is also shown. This is calculated from the casing OD and density. 2.6.11.3SPOT: Model inputs In order to use the SPOT inflow model, select | System | Inflow Performance and select | SPOT from the list of the available Reservoir Models in PROSPER:
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In order to fully describe the SPOT reservoir model, select | Input Data at the top right corner of the screen to access the various tabs (below listed from left to right) required to enter the model inputs: - Options - Layers - Log Data - Completion Data
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2.6.11.3.1 SPOT: Model inputs - Options
Lp Correlation Type: ·
“API19B Section 1- API 19B Section II or IV Conventional Correlations”- these correlations assume that effective stress applied in a Section II or Section IV test setup reaches the centre of the sample. The correlation should also be used for a Section 1 test (no effective stress applied)
·
“API 19B Section 1- API 19B Section II or IV Synthetic Rock Correlations”- these correlations are based on Shell laboratory tests in which it is believed that effective stress applied in a Section II or Section IV type test setup does not reach the centre of the core sample. These adjustments are made to reflect the fact that the perforation © 1990-2011 Petroleum Experts Limited
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depth of penetration under effective stress measured at surface in conventional Section II and IV setups is not the perforation depth that would be expected downhole under the same effective stress condition. It should be highlighted that effective stress applied using a triaxial test approach is believed to be valid and as such the “API 19B Section 1- API 19B Section 2 conventional correlations” option should be selected.
Calculate Non-Darcy Skin: ·
Yes: a quadratic is used to account for high velocity flow
·
No: the quadratic (non-Darcy skin) term is not taken into account.
The only option for gas/condensate wells is Yes. Activity: The user has two choices: New well: the well is being perforated for the first time or
· ·
Workover / Re-perforation: an already perforated and producing well needs to be re-perforated.
Well type: The well type can be: ·
Vertical
·
Deviated (up to 75 degrees deviation)
·
Horizontal (above 75 degrees deviation)
Inflow Equation: For vertical or deviated wells the user has 2 IPR choices: · Vogel: SPOT uses a straight line inflow relationship above the bubble point and the Vogel relationship below the bubble point to account for two phase flow. This equation is based on an empirical relationship developed by Vogel using numerical simulations. · Fetkovitch: the Fetkovich IPR model also accounts for two phase flow below the bubble point. It was developed to improve Vogel’s correlation. PROSPER Manual
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For horizontal wells the user has 4 IPR choices:· Economides-Joshi: This model has been adopted from Economides (1990) and Joshi (1988). It assumes the well is located in the center of the drainage volume. The method is not appropriate for partially cased and perforated or partially openhole perforated horizontal wells. · Borisov: This simple equation was developed by Borisov (1964) and has been found to provide good results in many simple cases. The method is not appropriate for partially cased and perforated or partially openhole perforated horizontal wells. · Babu-Odeh: This method treats a horizontal well as a vertical well turned sideways. Despite being a simple concept, it has received wide acceptance. The method is not appropriate for partially cased and perforated or openhole perforated horizontal wells. · Goode-Wilkinson: The method was adopted from Goode and Wilkinson. It is the only horizontal well model in SPOT that can be used to calculate performance of a partially cased and perforated horizontal well. The model also assumes that the horizontal well has been drilled in a rectangular drainage area that is twice as long as it is thick (I.e. reservoir length>>reservoir height). The method is not appropriate for partially openhole perforated horizontal wells. Note that Non Darcy skin effects are currently NOT considered in SPOT for horizontal gas wells.
Log Data Input: SPOT requires log data with porosity, permeability, UCS and TWC. However if not all these types are available then the missing data can be calculated from correlations. Also if other data such as FDC, shear & compressional sonic is available then it can be used to calculate the required data. In this combo-box, select the variables that you have available as log data. You will then be able to enter them in the log data tab. If no log data is available then select "None Available". The user will then be able to generate log data with constant values in the log data tab. Perforating Method: For a new well there are two options:· Single run perforating - Running in and perforating One perforating gun is run into the well and fired. This is as per ‘standard’ perforating practices. · Double run perforating - Running in and perforating, then running in again and perforating using the same gun © 1990-2011 Petroleum Experts Limited
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An interval is perforated twice using the same gun. That is, the gun is run into the well and fired, pulled out of the hole and the same gun is rerun into the well and fired. SPOT takes into account the probability that old and new perforations will overlie (assuming the perforating guns are not oriented). For a workover/reperforation:· Single run perforating - Running in and perforating One perforating gun is run into the well and fired. This is as per ‘standard’ perforating practices. · Double run perforating – Running in and perforating, then running in again and perforating using the same gun An interval is perforated twice using the same gun. That is, the gun is run into the well and fired, pulled out of the hole and the same gun is rerun into the well and fired. SPOT takes into account the probability that old and new perforations will overlie, assuming the guns are not oriented. For a double perforating run, SPOT will assume the same degree of mud invasion for the first and second perforating run. · Re-perforating - You are re-perforating over existing perforations (old holes) that are contributing to production If this option is selected the User must fill out the “Reperforating” box in the Reservoir layers screen. The User is presented with a drop down box that includes the following options ·
New holes only- i.e. model the contribution from only the new perforation holes
·
New and Old holes- i.e. model the contribution from the new and old perforation holes
·
Old holes only- i.e. model the contribution from only the old perforation holes. Note that according to the option selected here, the User must also tick the appropriate perforated interval in the Log Data screen
SPOT takes into account the probability that old and new perforations will overlie assuming guns are not oriented. As calculated reperforation results are qualitative, the User should match/adjust these results using field data. For a reperforation calculation, SPOT will assume the same degree of mud invasion for the old and new perforating run. In SPOT mud invasion is assumed to have a permanent effect on reservoir performance that does not improve over time. Thus, when reperforating an existing zone or perforating a new zone in an old well, SPOT will assume mud invasion properties do not alter over time (i.e. the existing zone will contain the same amount and degree of mud invasion as the new zone). In reality, if a mud has been ‘ideally’ designed, it is likely the effect of mud invasion will reduce over time. SPOT recognizes the fact that most of the PROSPER Manual
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drilling muds used in practice are not ‘ideal’. Despite this, if the User wishes to alter the mud invasion properties for new and old perforating zones within a well, the “Enter Mud Invasion Log” option should be selected. This will give the User the ability to specify certain mud properties for different zones.
(Mud) Invasion method: There are 4 methods available to capture the mud invasion: 1. "Calculate invasion" This option will allow the User to calculate mud invasion using one of four options developed by Shell. The model requires the following inputs: ·
Drilling fluid weight / density,
·
Total drilling time: This is the total drilling time (including downtime during drilling of the well) which is used to calculate an equivalent rate of penetration.
·
Drilling downtime: This is downtime/well suspension time after the well has been drilled i.e. the time that the total wellbore was exposed to drilling mud. Note that the model accounts for equilibrium filtrate invasion through the filter cake.
2. "Enter Mud Invasion Log" The User should enter a mud invasion petrophysical log. This is the most accurate method of predicting mud invasion depth in a well. Typically, a mud invasion log can be calculated using deep and shallow resistivity data; resistivity data can provide a good indication of mud invasion depth and if drilling filtrate has dissipated away from the near wellbore region (which is likely for high permeability reservoirs). As mud invasion depth calculations are resistivity tool dependant, the appropriate calculation method should be obtained from the tool vendor or obtained from a Petrophysicist or Log Analyst. In order to use this option, “Log data Input” must be selected as “Yes” and data entered into the Log data screen. This option can also be used if conventional petrophysical log data is not available but the User still wishes to import a footby-foot description of mud invasion depth. The effective permeability in the invasion zone must also be specified using the “Invasion” tab on the “Reservoir Layers” screen (two invasion zone permeability options are available- use of return permeability data or predicted return permeability factors). Invasion should be entered for each individual layer if a multi-layer reservoir is modeled. 3. "Enter discrete Invasion depth" The User should input a discrete mud invasion depth based on field knowledge, © 1990-2011 Petroleum Experts Limited
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information from deep and shallow resistivity petrophysical logs and/or well tests. If this option is selected, the effective permeability in the invasion zone as well as the discrete invasion depth should be specified using the “Invasion” tab on the “Reservoir Layers” screen (two invasion zone permeability options are availableuse of return permeability data or predicted return permeability factors). Invasion should be entered for each individual layer if a multi-layer reservoir is modeled. 4. "No Invasion" In this case, the SPOT module will assume no mud invasion.
Sanding model: There 2 choices: "None" and the "QinetiQ model". The "None" option will not calculate any possible production of failed sand. The "QinetiQ model" is an analytical model that calculates if failed sand will be produced from a vertical or horizontal perforation: ·
For vertical perforations a suspension model is assumed in which solid particles are maintained within the fluid
·
For horizontal perforations a conservative traction model is used in which sand particles do not enter the fluid but move by rolling and sliding. This transport mechanism requires the least energy for initiation.
Currently SPOT assumes: ·
in vertical wells, the horizontal perforation model is used
·
in deviated and horizontal wells both the horizontal and vertical transportation models are used. If either model results in sand production SPOT will identify that sand will be produced. The User should enter the perforation angle for the perforation type of interest.
This model can also be used as a debris transport model. Thus, it can be used to model debris flow if the debris diameter is entered (rather than the sand particle size distribution diameter) and if the density of the debris is entered (rather than the sand density). Model limitations include: ·
The model is not valid for mud or clay
·
The model does not account for random fluctuations in velocity due to turbulence that may, in reality, enable movement of particles even when no sand transport is indicated.
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·
The model assumes that the fluid of interest is the reservoir fluid (not the completion fluid or drilling mud).
·
A perforation angle cutoff of 45 degrees is used to distinguish between horizontal and vertical perforations
·
Validity is limited to rw/(perforation length+rw)<0.95. Beyond this, the equations will be operating beyond the intended range
The following input parameters are required: ·
Particle diameter: average expected particle diameter from sieve or laser particle size analysis
·
Density sand: the density of the sand grains
·
Perforation angle: defines the horizontal/vertical orientation of the perforation. The perforation angle is measured relative to the horizontal axis. i.e. perforation angle of a horizontal perforation equals 0 degrees. For vertical perforations the model assumes that the perforation is oriented downwards. It is assumed that if the perforation angle is oriented upwards (with an angle of 35 degrees-90 degrees from horizontal), the crushed zone material will fall out of the perforation tunnel.
·
Roughness perforation wall: the roughness of the perforation. A suggested value is one standard deviation greater than the average particle size to account for the presence of loose fines and crushed material, which will roughen the perforation tunnel.
It should be highlighted that the QinetiQ Sanding Model does not predict perforation tunnel failure. It only predicts if sand production will occur assuming that failure has already occurred. I.e. perforation tunnel cleanup.
Crushed zone Model: The user has two models to choose from: ·
Entered
·
QinetiQ Test Results
If the entered crushed zone model is selected, the user needs to input: o o
Permeability (impairment) factor, which represents the ratio of the crushed zone permeability to the virgin reservoir permeability and (Crushed zone) thickness
The “QinetiQ Test Results" option will use a default crushed zone permeability relationship which defines the thickness of the crushed zone and the crushed zone © 1990-2011 Petroleum Experts Limited
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permeability damage factor based on laboratory experiments using big hole charges.
Lower Completion Type: If the well completion type has been set to "Cased Hole" in the System Summary then the only option is "Cased and Perforated". If the well completion type has been set to "Open Hole" in the System Summary then there are two choices:·
Open Hole
·
Open Hole Perforated
Pressure Transform: This option is only required for gas/condensate wells. It refers to the pressure transform used in the IPR calculations. · Pressure Squared · Pseudo Pressure Use Downhole Standoff: Select "Yes" if you wish to enter a gun standoff. Otherwise select "No" in which case the gun is assumed to be centralized. Enter Gun per Layer: Select "Yes" if you wish to select a different gun for each layer in the reservoir. Select "No" if the same gun is to be used for the whole reservoir. Use SPOT IPR Extensions: Select "No" if you wish to use the same assumptions as other PROSPER IPR models. Select "Yes" if you wish to use the same assumption as the original SPOT program from Shell.
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2.6.11.3.2 SPOT: Model inputs - Layers
This tab is used:· to enter some basic data such as well radius · to split up the reservoir into layers and enter data per layer. · select a gun It is not necessary to enter multiple layers but at least one layer must be entered. Only one layer is allowed for horizontal wells. Basic Data:
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Well Radius - Wellbore hole radius Drainage Radius - Reservoir radius over which the well can drain/ inject reservoir fluids. In general, the drainage radius for tight formations is small, while the drainage radius for highly permeable formations is large. For the Joshi Economides and Borisov horizontal well methods the equivalent horizontal drainage radius should be entered into SPOT. That is, if the user nominates a drainage area, the shape of that drainage area is either elliptic or rectangular with two half circles at both ends. Radius of a circle with an equivalent area calculated and it is called the equivalent horizontal drainage radius. Note that drainage radius does not need to be defined in the Babu Odeh or Goode Wilkinson horizontal well method. Mean Sea Level wrt Origin, Sea Bed Depth wrt Origin - Used to calculate the effect of sea on in-situ effective stress (enter zero if on-shore). Perforation Efficiency - In the past perforation efficiency was often a very low number such as 0.2, 0.3. This was to take into account the much lower Lp than the gun test value caused by the difference in test and in-situ conditions. Since the Lp is corrected to insitu conditions by the SPOT calculations one would normally use a much larger perforation efficiency e.g. 0.8. If a gun is selected per layer then this will appear as a per layer value in the layers grid rather than the basic data. Additional Reservoir Height - This information will only be required for a vertical or deviated openhole or openhole perforated well. It defines the distance between the bottom of the openhole well and the bottom of the reservoir layer (i.e. the bottom-most reservoir layer in a multilayer reservoir). For example, if the openhole well fully penetrates the reservoir (as depicted below) the ‘additional reservoir height’ will equal zero.
If the openhole well does not penetrate the Bottom Reservoir Layer, the distance between the bottom of the well and the Bottom Reservoir Layer must be defined using the ‘additional reservoir height’ box.
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In an openhole vertical or deviated well the top of the producing well section will be defined by the bottom of the casing on the Completion Details screen. Thus the bottom of the casing and the ‘additional reservoir height’ will define the producing well length in an openhole vertical or deviated well. Select Gun: If gun per layer has not been selected, click this button to select a gun from the guns database. Select Old Gun: If gun per layer has not been selected and the user has chosen to reperforate existing perforations, click this button to enter details of the gun used to create existing perforations. Layer Data: Top MD - For all vertical and deviated wells this is the top of the specific reservoir layer to be analysed, defined in terms of measured depth. Thus: · Bottom MD - Top MD = reservoir height for a vertical cased and perforated well. · Top MD must be used in conjunction with ‘Additional Reservoir Height’ and ‘Bottom Well MD’ to define the reservoir height for an openhole or openhole perforated well. Bottom MD - For vertical and deviated cased and perforated wells this is the bottom of the reservoir layer to be analysed. Thus: · Bottom MD – Top MD= reservoir height · Well length is defined by the perforated interval on the Log Data screen. This is depicted below. Cased and perforated vertical well:
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Layer Pressure - Average current layer pressure. Under Balance Pressure - The total of static underbalance and dynamic underbalance when the interval was perforated. This value is used to illustrate on the Analysis Screen if the crushed zone around the perforation tunnel is likely to be removed and to facilitate comparison of the desired underbalance to industry models. Note: · SPOT does not automatically adjust perforation crushed zone properties according to the specified underbalance value. A specific modelling package should be used for this purpose. · Underbalance pressure can be static or dynamic or a total of static and dynamic · If a negative value is entered, SPOT assumes an overbalance has been applied. · The use of vertical effective stress (rather than horizontal effective stress) to determine crushed zone removal is theoretically only valid for certain perforation orientations. Overburden Pressure Gradient - This pressure gradient is used to calculate the overburden pressure and subsequently the Near Wellbore Effective Vertical Stress (NWEVS). The NWEVS is used in perforation depth of penetration calculations. A common overburden pressure gradient (i.e.lithostatic pressure gradient) is 1psi/ft. Water saturation - The total water saturation in the reservoir. This value is used to predict the effect of associated water production on well productivity. Relative Permeability - Click this button to enter the relative permeability curves for oil&water (for oil wells) or gas&water (for gas/condensate wells) as Corey data. Reperforating Options - If the User has selected to reperforate existing perforations, they can chose whether the calculation is based on “new & old holes”, “new holes only” or “old holes only”. Invasion Data - If you have chosen Invasion model to be "Calculate Invasion" or "Enter Discrete Invasion Depth", click this button to enter details of the invasion data.
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Bottom HoleTemperature - Enter the average reservoir temperature over the perforated interval of the layer. Kv/Kh - The ratio of vertical to horizontal permeability. The ratio must be less than or equal to 2. m - If permeability information is unavailable, the User will need to enter a coefficient to describe a porosity/permeability relationship. M is the gradient of the porosity/ permeability relationship c - If permeability information is unavailable, the User will need to enter a coefficient to describe a porosity/permeability relationship. C is the y-axis intercept of the porosity/ permeability relationship. Downhole Rock Type - The rock type to be used in the perforation calculation must be selected.(carbonate or sandstone). This will affect the perforation depth of penetration calculation. It should be highlighted that SPOT does not take karsts and fractures into account when modeling inflow performance of carbonates. This may result in unrealistic flow results. Reservoir Height - This defines the distance between the top and bottom reservoir layer in which the horizontal well has been drilled. For the Economides Joshi and Borisov horizontal methods, it is assumed that the well is positioned in the mid point of the layer. The Babu-Odeh and Goode Wilkinson methods allow the height of the reservoir to be specified relative to the well position. The Economides Joshi, Borisov, Babu Odeh and Goode Wilkinson horizontal methods allow the following type of horizontal well situation to be analysed:
The Babu Odeh and Goode Wilkinson horizontal methods allow the following type of horizontal well situation to be analysed:
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Xwell - The distance to the well mid point in the direction of reservoir length. This parameter only needs to be defined for the Babu Odeh and Goode Wilkinson calculation methods Ywell - The distance to the well mid point in the direction of reservoir width. This parameter only needs to be defined for the Babu Odeh and Goode Wilkinson calculation methods. Zwell - The distance to the well mid point in the direction of reservoir height. This parameter only needs to be defined for the Babu Odeh and Goode Wilkinson calculation methods. Reservoir Length - Length of the reservoir defined for Babu Odeh and Goode Wilkinson methods. Reservoir Width - Width of the box reservoir defined for Babu Odeh and Goode Wilkinson methods. 2.6.11.3.2.1 SPOT: Model inputs - Rel Perm Data
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The User must select Corey Function in the “Reservoir Layer” screen. End points (residual saturations and corresponding relative permeabilities) as well as Corey Exponents must be specified. A brief explanation of these terms is provided below: · Relative permeability: Permeability of one phase in the presence of another phase · Residual saturation: The irreducible saturation remaining in the pore space when another phase flows through the reservoir rock · End point relative permeability: The permeability corresponding to the residual saturation of the other phase/phases · Corey exponent: An exponent that describes the shape of the relative permeability curve between endpoint saturations For example, in the below graph: · Residual water saturation=0.2 (20%) · Residual oil saturation= 0.2 (20%) i.e. 1-0.8 · Oil relative permeability end point at the residual water saturation of 20%= 0.8 · Water relative permeability end point at the residual oil saturation of 20%= 0.3 · If water saturation is less than or equal to 20% then it can be assumed that only oil is flowing in the reservoir · If oil saturation is less than or equal to 20% then it can be assumed that only water is flowing in the reservoir
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General rules to be used when specifying relative permeability values are provided below (ideally, Corey Exponents would be obtained from laboratory experiments): End point relative permeability <1 Residual saturations 0-1 (i.e.0-100%) Recommended Corey Exponent for Gas/Oil Drainage In order to estimate a Corey Exponent, the wettability of the reservoir must first be determined. Wettability describes the preference for fluid to adhere to the surface of the reservoir rock (i.e., in water wet rocks water preferentially adheres to the rock surface, conversely, in oil wet rocks oil preferentially adheres to the rock surface). In general, most reservoirs are classified as being ‘intermediate wet’. Guidelines for Wettability Determination:
Swi
WaterWet >20 to 25% or more
Oil-Wet <15%, usually 10%
kro=krw
@ Sw >50%
@ Sw< 50%
krw at Sorw
< 0.3
> 0.5
Approximate Corey Exponents vs. Wettability
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Wettability
Corey Exponent for kro (no)
Corey Exponent for krw (nw)
Water Wet Intermediate Wet Oil Wet
2 to 4 3 to 6 6 to 8
5 to 8 3 to 5 2 to 3
Recommended Corey Exponents for Gas Production (an imbibition process) Curve Water relative permeability curve Gas relative permeability curve
Corey Exponent 5 to 8 2 to 4
Note: This assumes that the reservoir is water wet Curve
Corey Exponent
Gas relative permeability curve
2 to 4
The User can easily view the generated relative permeability curve by clicking “Plot Curves in the “Corey Function data” screen. Relative permeability assumptions used in SPOT are outlined below: -Oil production- oil, water and solution gas are assumed to be the only phases present -Gas production- gas and water are assumed to be the only phases present -Water production- water is assumed to be the only phase present -Water injection into an aquifer- water is assumed to be the only phase present -Water injection into oil reservoir- water and residual oil are assumed to be the only phases present -Gas injection into a gas cap- gas and irreducible water are assumed to be the only phases present -Gas injection into an oil reservoir- gas, oil and irreducible water are assumed to be the only phases present Thus, it is important that the User selects the correct reservoir type on the Corey Function screen for injection. That is: -For water injection if “injecting in oil leg” is not ticked, SPOT assumes that water is being injected into a water aquifer -For gas injection if “injecting in oil leg” is not ticked, SPOT assumes that gas is being injected into a gas cap.
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2.6.11.3.2.2 SPOT: Model inputs - Mud Invasion
SPOT contains four mud invasion data entry options on the New well data and Reperforation data screens: 1. No Invasion”: The SPOT calculation assumes no mud invasion. 2. Enter discrete invasion depth”: The User should input a discrete mud invasion depth based on field knowledge, information from deep and shallow resistivity petrophysical logs and/or well tests. If this option is selected, the effective permeability in the invasion zone as well as the discrete invasion depth should be specified using the Invasion tab on the PROSPER Manual
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Reservoir Layers screen (two invasion zone permeability options are available- use of return permeability data or predicted return permeability factors). Invasion should be entered for each individual layer if a multi-layer reservoir is modeled. 3. Enter mud invasion log”: The User should enter a mud invasion petrophysical log. This is the most accurate method of predicting mud invasion depth in a well. Typically, a mud invasion log can be calculated using deep and shallow resistivity data; resistivity data can provide a good indication of mud invasion depth and if drilling filtrate has dissipated away from the near wellbore region (which is likely for high permeability reservoirs). As mud invasion depth calculations are resistivity tool dependant, the appropriate calculation method should be obtained from the tool vendor or obtained from a Petrophysicist or Log Analyst. In order to use this option, Log data available? must be selected as Yes and data entered into the Log data screen. This option can also be used if conventional petrophysical log data is not available but the User still wishes to import a foot-by-foot description of mud invasion depth. The effective permeability in the invasion zone must also be specified using the Invasion tab on the Reservoir Layers screen (two invasion zone permeability options are available- use of return permeability data or predicted return permeability factors). Invasion should be entered for each individual layer if a multi-layer reservoir is modeled. 4. "Calculate invasion": This option will allow the User to calculate mud invasion using one of four options developed by Hans Vans Velzen (Royal Dutch Shell) and the Shell Perforating Global Delivery Team. If mud invasion is to be calculated in SPOT, the User must input: o Total drilling time: This is the total drilling time (including downtime during drilling of the well) which is used to calcuate an equivalent rate of penetration. o Downtime: This is downtime/well suspension time after the well has been drilled i.e. the time that the total wellbore was exposed to drilling mud. Note that the model accounts for equilibrium filtrate invasion through the filtercake. Calculation specifics and the effective permeability in the invasion zone must also be specified using the Invasion tab on the Reservoir Layers screen (two invasion zone permeability options are available- use of return permeability data or predicted return permeability factors). Invasion should be entered for each individual layer if a multi-layer reservoir is modeled. The four calculation methods available on that screen are: o Ability to estimate mud/ filtrate invasion if fluid loss data from laboratory experiments were recorded as a function of time. Common experiments © 1990-2011 Petroleum Experts Limited
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include measuring High Temperature High Pressure filtration behavior (under static conditions using a ceramic disk with appropriately sized pores) and Core Flood tests. o Ability to estimate mud/ filtrate invasion if only the total fluid loss volume from laboratory experiments was recorded. Common experiments include measuring High Temperature High Pressure filtration behavior (under static conditions using a ceramic disk with appropriately sized pores) and Core Flood tests. o Ability to estimate mud invasion if no test data is available-Option 1 o d) Ability to estimate mud invasion if no test data is available- Option 2. In many circumstances, a User will only have information available for this calculation. It should be highlighted that this method is only valid within the following ranges: mud weights of 1sg to 1.8sg, brine densities of 1.05sg to 1.25sg for oil based mud and 1sg to 1.25sg for water based mud. This will provide a very similar answer to Option 1. The difference between Option 1 and Option 2 is the data input requirements. Mud Invasion Model- Background Information The SPOT mud invasion model is appropriate for the following scenarios: · Oil based and water based drilling muds · Oil production wells · Gas injection and production wells · Water injection and production wells · Sandstone and carbonate reservoirs · Vertical, deviated and horizontal wells · Different completion types including cased and perforated wells, openhole completions and openhole perforated wells. The model assumes the drilling mud has been correctly designed and that appropriate laboratory tests have been undertaken (tests may include, but not be limited to return permeability, filtercake pop off and core flood). Correct mud design is especially important as: · In general, deep mud filtrate invasion depths depend on filtercake thickness and permeability. 1. Filtercake permeability depends on the solid size used to create a filtercake. 2. Filtercake thickness depends on the tendency to be eroded under specific conditions (based on initial thickness and mud flow/ dynamic filtration PROSPER Manual
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effects). Thus, if drilling mud solid particles are not correctly sized, the formation will experience deeper mud filtrate invasion. The SPOT mud model assumes that all drilling mud solids have been optimally sized. · Return permeability tests can be used to define the permanent permeability reduction due to mud filtrate and solids invasion. It should be highlighted that solids invasion should be negligible if a mud has been correctly designed. · Filtercake pop off/ flow back tests can be used to define the differential pressure required for filtercake removal. Note that residual solids at the surface of the wellbore will have a much larger impact on return permeability than filtrate invasion so it is important to ensure the filtercake has been removed (Francis, 1997, SPE Paper 38182). If a drilling mud has been properly designed, the filtercake should easily lift off and no residual solids should remain at the surface of the wellbore. It should also be highlighted that the mud calculation model in SPOT can only be used to obtain a first pass estimate of mud invasion depth. If the depth of penetration of the perforating gun and mud invasion depth is similar, more detailed studies and/or laboratory testing should be undertaken. Such studies can account for additional factors such as dynamic filtration effects. An example of such a study using a fine scale 3D reservoir simulator is described by Suryanarayana et. al in SPE Paper 95861. Users should always conduct an After Action Review to compare the mud invasion depth predicted by the model to that in the actual well (e.g. mud invasion depths in the well can be measured using deep and shallow resistivity logs). This information will assist design and interpretation of mud invasion depths in adjoining fields/wells. It would be appreciated if results of any such comparison are sent to Petroleum Experts for future improvement of the SPOT mud invasion model. Some recognized limitations of the SPOT mud invasion model include: · It is possible to generate inconsistent skin and flow results when using high 'mud filtrate zone' factors. If this occurs we recommend increasing the filtrate factor to 100percent or reducing the filtrate factor below 50percent. A model to rectify this problem will be avaliable in the next version of SPOT. The correct behaviour is that flow reduces (and skins increase) as mud invasion depth increases. · It assumes the mud has been correctly designed including sizing of mud solids. · Athough it can be applied to oil, gas and water flow, the model assumes piston like displacement of filtrate. This is in general valid for gas wells, however, may not be appropriate for oil wells. If the viscosity of the filtrate is lower than the viscosity of the reservoir fluid, “fingering” may occur, resulting in much higher invasion depths than predicted by the SPOT model. In order to correctly model this effect, multiphase flow effects must be taken into account. · It is a static model and neglects dynamic effects such as filter cake erosion. © 1990-2011 Petroleum Experts Limited
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Dynamic effects (constant removal and relayering of the filtercake) may be significant in horizontal wells during the drilling and completion process. · A constant mud filtrate damage permeability is assumed in the mud invasion zone. There are varying opinions in the industry if the mud invasion zone should be modeled with a constant or varying permeability. The assumption in SPOT is that permeability of the filtrate invasion zone is not depth dependant. The alternate belief is that permeability should vary within the mud invaded zone from a low value (closest to the wellbore) to virgin reservoir permeability (at the edge of the invasion zone), reference: SPE 95861. · The following analysis assumes that the filtrate invasion into the reservoir has a permanent effect on well productivity, which does not improve over time. The degree of permanent reservoir permeability reduction due to filtrate and solids invasion is captured in SPOT in the specification of invaded reservoir permeability (Ks and Kl- permeability of the solids and liquid invaded zones respectively). Thus it is very important that these values are reasonable and if possible, return permeability testing has been undertaken (return permeability tests demonstrate the difference in pre and post mud invaded permeability i.e. the amount of permanent mud damage). To obtain realistic return permeability results, the test should be continued until a constant flow rate is achieved and the drawdown pressure used in the laboratory should be representative of the maximum pressure experienced in the field (this pressure must be downscaled for core-reservoir size effects). In addition, test conditions like temperature, overbalance pressure and pore sizes of the disk and/or the permeability of the core plug sample, should be comparable with field conditions. If specific, remedial attempts are undertaken to remove mud damage, the effect of these processes should be included in the final estimate of return permeability. · Equivalent Circulating Density (ECD) effects during mud circulation are ignored. ECD effects may increase the differential pressure across the formation during filtercake formation and filtrate invasion. · Formation composition (e.g. clay presence, mineralogy) is ignored. Mud Invasion Model Input Requirements Input data for calculating mud invasion, specifying a discrete mud invasion depth or a mud invasion log is specified under the New Well/Reperforation screen: Once an option is selected, additional mud invasion data must be entered on the Reservoir Layers screen, Invasion Data. Irrespective of the option selected on the New Well/Reperforation screen (except for the “No invasion” option), the effective permeability in the mud filtrate and mud PROSPER Manual
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filtercake invaded zones must be specified. Two options are available for specifying the effective permeability of the invaded zone: 1. Input return permeability from core tests. This option should be selected if return permeability laboratory testing was undertaken. Simplistically, the test involves measuring the initial permeability of the sample at irreducible water saturation, dynamically exposing the core to drilling mud so a filter cake forms, statically exposing the filter cake to drilling fluid, cleaning up the sample using drawdown and finally, measuring the return permeability of the core sample. The damaging effect of the drilling mud is quantified by the difference between the initial and final permeability of the core sample. To use this option, the following inputs are required: Fluid loss at end of test= total mud fluid loss Cross sectional area= cross sectional area of core sample Fractional porosity of core sample= average porosity of core sample Length of core plug sample=length along the axis of the core sample Swi of core sample= irreducible water saturation of core sample Kreturn= return permeability of the core sample after conducting the laboratory test (%) Kinitial= initial permeability of the core sample i.e. 100% by definition This information is used to determine a linear fluid invasion depth, and thus the effective permeability of the fluid invaded zone. 2. Input factor for permeability in mud invaded zone: If return permeability laboratory testing was not undertaken, the effective permeability if the solid and filtrate invaded zones must be estimated. This is inputted into SPOT is the form of mud invasion zone permeability factors, Ks and Kl,: Ks = factor to describe the final permeability of the solid invasion zone following mud invasion Kl = factor to describe the final permeability of the filtrate invasion zone following mud invasion Suggested values based on research by Hans Van Velzen (Royal Dutch Shell) are as follows: · Kl (OBM) = 52% Kl(WBM) =62% (90% probability that the invaded zone permeability will be greater than this) · Kl (OBM) = 89% Kl(WBM) =91% (50% probability that the invaded zone permeability will be greater than this) · Ks(OBM & WBM)= 5% © 1990-2011 Petroleum Experts Limited
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· Research suggests that a cut-off may exist for mud invasion damage depending on initial permeability(i.e. high permeability reservoirs are not greatly affected by mud invasion). The mud invasion model used in SPOT accounts for irreducible water saturation and, as such, a ‘permeability cutoff’ is not recommended for gas reservoirs. However, a ‘permeability cutoff’ could be applied to oil reservoirs. · Alternate work by Francis (1997) suggests: Ks (OBM & WBM)= 0.1% (Reference: Francis, 1997, “Dominating Effect Controlling the Extent of Drilling Induced Formation Damage”, SPE Paper 38182) · If the drilling mud is inappropriate or has been poorly designed, permeability in the mud invaded zone may be very low due to pore plugging by solids, fluid/ fluid and fluid/ rock interactions, changes in saturation, phase blockage, clay swelling in the formation, wettability alterations and in situ emulsification and/or precipitation. The mud invasion model in SPOT does not explicitly consider these factors. In addition, the User must enter an ‘irreducible water saturation’ or ‘irreducible gas saturation’ value. This is the irreducible fluid saturation of the reservoir interval. If “Enter Discrete Invasion Depth” was selected in the New Well/Reperforation screen, a value should be entered into the “Discrete invasion depth” box on this Invasion Data screen. This option will assume a constant invasion depth over the entire reservoir interval. If “Calculate invasion” was selected in the New Well/Reperforation screen, one of the following four mud invasion depth calculation options should be selected: 1. Fluid loss vs time 2. Total fluid loss time and volume 3. No fluid loss data-option 1 4. No fluid loss data- option 2 Most accurate calculation method is Option 1, followed by Options 2, 3 and 4. However the option that requires the least data and thus is most easily applied by the User is Option 4. In many circumstances (especially for high permeability gas and oil reservoirs), the User will only have data available for Option 4. 1. Fluid loss vs time This option should be selected if core flood tests and/or HTHP-fluid-loss-tests (using a ceramic disk) were conducted and if fluid loss behaviour during the duration of the test is avaliable. It will predict the amount of spurt loss as well as the external filter cake build-up process (excessive spurt loss will occur if the drilling fluid is not properly designed, in this case the drilling fluid should be redesigned). The User will need to enter additional data in the Fluid loss data screen: o Area of lab sample= cross sectional area of ceramic disk or core sample PROSPER Manual
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o Differential pressure applied across the lab sample= differential pressure applied across ceramic disk or core sample during the mud invasion test o The User will also need to enter “Time” and “Fluid Loss” data into the table. A minimum of two data sets is required. If more than two data sets are entered, SPOT will input a best fit line through the data. Reasonable values for t1 and t 2 are 300s and 1800s or the end time of the static filtration period respectively.
2. Total fluid loss time and volume This option should be selected if core flood tests and/or HTHP-fluid-loss-tests (using a ceramic disk) were conducted and if only the total fluid loss volume was recorded at the conclusion of the test. SPOT thus assumes that no spurt loss has occurred during the test (there should be minimal spurt loss if a drilling fluid has been optmally designed). As a consequence the solids invasion depth cannot be predicted and only the liquid invasion can be estimated. If the User is interested in spurt loss effects, they should obtain appropriate measurements using laboratory tests. The User will need to enter additional data in the Fluid loss data screen: o Area of lab sample= cross sectional area of ceramic disk or core sample o Differential pressure applied across the lab sample= differential pressure applied across ceramic disk or core sample during the mud invasion test o Total lab sample exposure time= time that the ceramic disk or core sample was exposed to drilling mud o Total fluid loss through the lab sample= total amount of drilling fluid lost through the lab sample during all testing stages (the volume should correspond to the total lab sample exposure time specified)
3. No fluid loss data-option 1 If no fluid loss data is available, empirical equations are used. This method assumes no spurt loss has occurred and that: o Fractional porosity of filtercake (fcake) [-] = 0.05 o Permeability of filtercake (Kcake ) [m2] = 80E-21 for OBMs o Permeability of filtercake (Kcake ) [m2] = 160E-21 for WBMs
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As these values are highly approximate, it is recommended that mud testing is undertaken to allow one of the more accurate methods (Option 1 or 2 above) to be used to estimate mud invasion depths. The User will need to enter additional data in the Drilling mud properties screen: o Oil based mud or water based mud. If “Oil based” mud is not selected, SPOT will assume the use of water based mud o Viscosity of drilling fluid filtrate o Density of drilling fluid filtrate, if you have an OBM this will be the density of the oil phase in the mud, if you have a WBM this will be the density of the water phase in the mud o Mass fraction of solids in the drilling fluid, if you have an OBM, this will be the mass fraction of solids and water i.e. mass fraction= [((%oil+%water+% solids)*drilling weight)-(%oil*densityoil)]/( (%oil+%water+%solids)*drilling weight), if you have a WBM, this will be the mass fraction of solids only i.e. mass fraction= [((%oil+%water+%solids)*drilling weight)-(%oil*densityoil)-(% water*densitywater)]/( (%oil+%water+%solids)*drilling weight) o Density of solids in the drilling fluid, if you have an OBM, this will be the density of solids and water i.e. density= [((%oil+%water+%solids) *drillingweight)-(%oil*densityoil)]/ (%water+%solids), if you have a WBM, this will be the density of solids only i.e. [((%oil+%water+%solids)*drilling weight)(%oil*densityoil)-(%water*densitywater)] / (%solids) 4. No fluid loss data- option 2 This method assumes no spurt loss has occurred. It should give a very similar result to Option 3 (it is based on similar empirical correlations). It should be highlighted that this method is only valid within the following ranges: mud weights of 1sg to 1.8sg, brine densities of 1.05sg to 1.25sg for oil based mud and 1sg to 1.25sg for water based mud. The method will also not work for some low weight water based muds (with brine densities between 1sg and 1.25sg). The User will need to enter additional data in the Drilling mud properties screen: o Oil based mud or water based mud. If “Oil based” mud is not selected, SPOT will assume the use of water based mud o Brine density o If an oil based mud, is the oil water ratio closer to 80/20 or 75/25 o Is the mud barite weighted or calcium carbonate weighted?
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o Drilling fluid weight In addition to selecting one of the four above options, the irreducible fluid saturations must be specified. Depending on the reservoir fluid, the following parameters may be required: a. Irreducible water saturation b. Irreducible gas saturation c. Irreducible oil saturation SPOT will always assume that the mud invasion zone is measured from the wellbore radius. That is: · in a cased and perforated well, invasion depth is measured from the wellbore radius (or if caliper data is entered, the effective wellbore radius) · in an openhole well the invasion depth is measured from the wellbore radius (or if calliper data is entered, the effective wellbore radius) · in an underreamed gravel packed well the invasion depth is measured from the underreamed wellbore radius (or if caliper data is entered, the effective wellbore radius)
2.6.11.3.2.3 SPOT: Model inputs - Old Gun
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SPOT takes into account the probability that old and new perforations will overlie assuming guns are not oriented. It is assumed that there is a negligible effect of the few shots which may overlay. As calculated reperforation results are qualitative, the User should match/adjust these results using field data. If the option of Old holes only or New and Old holes is selected, the User will be required to input the following data on the Reservoir Layer screen for the existing holes: Most of the required information can be obtained from the Vendor Database: · Gun size · Shot density · Gun phasing · DoP Section 1: the depth of penetration measured during the API RP19B Section 1 test · Entrance hole diameter · Perforation efficiency: perforation efficiency is the number of holes that are contributing to production. E.g. 80% efficiency would mean that 8 out of 10 holes are contributing to production as 2 hole are blocked due to debris, perforation collapse etc. Rough rules of thumb for perforation efficiency are: o 80% for a current perforation gun in a vertical well. o 50% for vertical perforations in a horizontal well (the gun sitting on the low side of the hole will prevent tunnel cleanup) o 80% efficiency for casing conveyed perforating o 80% efficiency for casing conveyed perforating o <80% efficiency if a large dynamic or static drawdown is applied to consolidated sand (i.e. tunnel collapse is not a concern) o 50% for old perforation guns (greater than or equal to 20 years old) o 50% for very tight reservoir · Deep Penetrating/ Big Hole: the type of gun must be selected and if the gun is classified as a deep penetrating or big hole charge. In general, a deep penetrating gun will have an entrance hole less than or equal to 0.5in. · Standoff during test: This is the distance from the outside of the perforating charge case to the inside of the casing that applies to the specified Section 1 DoP value provided above. · Downhole standoff: This is the distance from the outside of the perforating charge case to the inside of the casing when the gun was originally fired in the well. · Casing material: Select between J55, L80, P105 or P110. If a different material was used in the test, pick the material with the closest hardness. i.e.: Material J55 L80 P105 P110 Mean Brinell Hardness 180 230 275 320
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2.6.11.3.3 SPOT: Model inputs - Log Data
The Shell PGDT recommends that the following set of log data is inputted in SPOT to improve perforation and inflow performance predictions (i.e. answer “YES” to “Log data available?”): · Porosity · Permeability · Unconfined Compressive Strength (UCS) · Thick Walled Cylinder Strength (TWC) If UCS and TWC data is not available, the following information should be entered: · Formation Density Compensated (FDC) © 1990-2011 Petroleum Experts Limited
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· Compressional Sonic · Shear Sonic Petrophysical data should be entered on a typical data acquisition scale (i.e. 0.5-1ft). Additional data that may also be entered in the Log data screen is listed below (these are not used in the SPOT calculations): · Gamma-ray: to identify different formation types e.g. sand, shale, coal · Resistivity: to identify hydrocarbon intervals · Cement Bond Log (CBL): to identify poorly cemented zones · Caliper: the caliper diameter should be entered. This will be used to identify washed out and slumped zones. Any caliper data entered in SPOT will be used to define the wellbore radius in inflow performance calculations · Net/Non Net reservoir: to identify net pay or sand zones The best method to get log data into PROSPER is to first import it into Excel and preprocess it to the format of the log data tab. Then copy and paste it into PROSPER. Once all the data has been entered, click the "Fill-in" button to calculate any columns that were not entered (these are shown in blue). Perforation Zones The tick box in the "Perforated" column allows each row to be perforated or not. If the perforated tick box is blue and disabled then it means the log row depth does not intersect any of the entered layers so it can not produce/inject. Obviously it can be time-consuming to tick or untick each log row as there may be thousands or rows. So there are several methods to make this process easier:Multiple Selection: Select a number of rows by clicking and dragging over the rows. Then right click on the selected rows and select either "Perforated - On" or "Perforated - Off" to tick or untick the Perforated tick box for all the selected rows. Perf by cutoff:Click this button to display a dialog that allows rows to be perforated by cutoff e.g. perforate all rows with a permeability grater than 10 md. Perf by depth:Click this button to display a dialog that allows rows to be perforated or not over a range of entered depths e.g. perforate all rows between a MD of 10105 and 10674 feet. Note that if the Goode-Wilkinson horizontal well model is not selected for a cased and perforated analysis, the User will be unable to update the perforation interval in the Log Data screen (the entire interval will be automatically selected as being perforated). Unconfined Compressive Strength (UCS) and Thick Walled Cylinder (TWC) Data
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The User should input a UCS petrophysical log into SPOT. UCS is a very important parameter as it affects the perforation depth of penetration. There are four options for determining UCS: 1. Determine a UCS log for your field using petrophysical measurements (UCS is usually a function of density and sonic logs) and match the generated UCS log to laboratory core UCS measurements at specific depths. The complete UCS log should be easily acquired from a Petrophysicist or Log Analyst. This is the most accurate method of creating a UCS log as the predictive correlation will have been match against actual field core UCS measurements. For example: 2. Determine a UCS log for your field using petrophysical measurements (UCS is usually a function of density and sonic logs). The UCS log is NOT matched against core data. The complete UCS log should be easily acquired from a Petrophysicist or Log Analyst. 3. Determine a UCS log for your field using information/ data from nearby wells/fields 4. Use correlations in SPOT to estimate UCS. The following correlation types are available in SPOT to estimate UCS under the “UCS Relation” column in the layer data tab: Sandstone Reservoirs · - Equation 1: UCS as a function of density and compressional sonic (uncertainty factor 2) · - Equation 2: UCS as a function of density and shear sonic (uncertainty factor 2) · - Equation 3: UCS as a function of porosity (valid for porosity>7%) · - Equation 4: UCS as a function of TWC (uncertainty factor of 2) Carbonate Reservoirs · - Equation 5: UCS as a function of porosity (valid for porosity 4-37%) · - Equation 6: UCS as a function of TWC (uncertainty factor of 3) SPOT may request more information than required by the selected UCS correlation. For example, the User may select ‘Porosity, Permeability, FDC and Compressional Sonic’ from the ‘Log data input’ drop down menu in the options tab, however if Equation 1 is selected, only FDC and Compressional Sonic will be used to calculate UCS (porosity and permeability values are required for other calculations in SPOT). If the User wishes to use petrophysical log data to calculate UCS but only average values to calculate inflow performance, they should enter petrophysical FDC and Sonic logs and constant porosity and permeability values in the columns in the log data tab. Although it is possible to internally calculate porosity in SPOT for oil and water wells, it is recommended that porosity values are not calculated within SPOT and that porosity information is always entered by the User after it has been determined by a Log Analyst/ Petrophysicist (as it can have a large effect on mud invasion depth calculations and permeability correlations, and subsequently inflow values). To internally calculate porosity in SPOT for an oil or water well a FDC (density) Petrophysical log and a Rock Bulk Density value must be provided. Mud invasion effects are ignored in the SPOT porosity calculation. SPOT does not allow the User to internally calculate porosity for gas wells as density logs measure electronic density (which can be significantly less than actual density in gas). Many of these correlations are based on trend lines and as such, there is uncertainty © 1990-2011 Petroleum Experts Limited
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surrounding each correlation. The User should assess the appropriateness of calculated values to determine if the correlation is reasonable compared to expected UCS ranges. A relationship should not be used if it produces negative or very large values. If uncertainty exists regarding the UCS estimation it is recommended to conduct a sensitivity analysis. Indicative UCS ranges that can be used to assess the reasonableness of calculated values are: Unconsolidated/extremely weak Loosely consolidated/ very weak/soft Friable/weak Consolidated/low strength Hard Medium Strength High Strength Extreme Strength
<130 psia 130-550 psia 550-1300 psia 1300-4500 psia >4500 psia 4500-7200 psia 7200-17000 psia >17000 psia
These ranges should be appropriate for both sandstones and carbonates. After UCS values have been defined, TWC must also be defined (accurate TWC estimation is not as important as UCS prediction in SPOT as TWC is only used to predict perforation tunnel strength). The following correlation types are available in SPOT to estimate TWC under the “TWC Relation” column: · Sandstone Reservoirs - Equations 1 & 2: TWC as function of density and compressional sonic (uncertainty factor 1.5-2.5) - Equation 3: TWC as a function of density and shear sonic (uncertainty factor 1.52.5) - Equation 4: TWC as a function of porosity - Equation 5: TWC as a function of UCS (uncertainty factor of 2) · Carbonate Reservoirs - Equation 6: TWC as a function of porosity - Equation 7: TWC as a function of UCS (uncertainty factor of 3) SPOT may request more information than required by the selected TWC correlation. For example, the User may select ‘Porosity, Permeability, FDC and Compressional Sonic’ from the ‘Log data input’ drop down menu in the options tab, however if Equation 1 is selected, only FDC and Compressional Sonic will be used to calculate TWC (porosity and permeability values are required for other calculations in SPOT). If the User wishes to use petrophysical log data to calculate TWC but only average values to calculate inflow performance, they should enter petrophysical FDC and Sonic logs and constant porosity and permeability values in the columns in the log data tab. No Log Data Available If the "Log Data Input" in the options tab was set to "None Available" then synthetic log PROSPER Manual
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data must be generated. The screen to generate this data will be displayed automatically the first time the log data tab is accessed. To regenerate the log data again, click the generate button. 2.6.11.3.3.1 SPOT: Model inputs - Generate Log Data
This dialog is used to generate synthetic log data if none is available. This will create log data with constant values entered in the average properties data. The log depth increment should be a small number (e.g. 1 ft). 2.6.11.3.3.2 SPOT: Model inputs - Perforation Cutoff
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This dialog allows the perforated state of the log rows to be set depending on the values of the log data. For example, if you wish to only perforate log rows where the permeability is greater than 10 mD, enter a value of 10 mD for the "Lower Permeability" and then click the "Apply Cut-off" button. Log rows with a permeability greater than 10 mD will have the "Perforated" tick box selected and any with a permeability lower than 10 mD will have the "Perforated" tick box de-selected. Alternatively if you wish to only perforate log rows with a UCS less than 7000 psia, enter a value of 7000 psia for the "Upper UCS" and then click the "Apply Cut-off" button. Log rows with a UCS less than 7000 psia will have the "Perforated" tick box selected and any with a UCS higher than 7000 psia will have the "Perforated" tick box de-selected. Leave fields blank if you do not want to them to be applied in the cut-off. 2.6.11.3.3.3 SPOT: Model inputs - Perforation Depth
This dialog is used to select or deselect the perforate tick box for all log rows over a certain depth range. The depths are always MD rather than TVD. For example, if you wish to perforate between 12050 and 12100 feet, enter "Upper Depth" = 12050 ft and "Lower Depth" = 12100 ft. Then click the "Set Perforated" button.
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2.6.11.3.4 SPOT: Model inputs - Completion
This tab is used to enter completion details for the SPOT calculations. Only the completion over the producing zone is required. This data is used to correct the Lp. API 19B/43 tests are performed through a casing defined in the test data. So if if a thicker casing is used then it will decrease the Lp as more of the gun energy is lost perforating the casing. Or if a thinner casing is used then the Lp will be higher. Appropriate completion details will need to be entered for the selected option. This may include: © 1990-2011 Petroleum Experts Limited
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· Casing diameter, type and weight · Casing drift to account for variations in diameter during manufacture. The total drift in casing internal diameter (ID) should be entered. This is defined in SPOT as the difference between the maximum and minimum casing ID. · Tubing diameter, type and weight · Tubing drift to account for variations in diameter during manufacture. The total drift in tubing internal diameter (ID) should be entered. This is defined in SPOT as the difference between the maximum and minimum tubing ID. · Minimum tubing restriction diameter: this limits the gun size that can be run using through tubing conveyance. · Hold up depth; this is effectively the end of the well. You will not be allowed to perforate below the hold up depth · Casing material type: select between J55, L80, P105 or P110. If a different material was used in the test, pick the material with the closest hardness. i.e.: Material J55 Mean Brinell Hardness 180
L80 230
P105 275
P110 320
SPOT will always assume that the casing of a well is cemented. It cannot calculate the effect of perforating an uncemented liner or tubing. Multiple casing strings (2 or 3 casing strings only) can be entered into SPOT and an adjusted perforation depth will be calculated using empirical correlations. The holdup depth is effectively the bottom of the well. No perforations are allowed below the holdup depth. The holdup depth is a measured depth (not TVD).
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2.6.11.3.5 SPOT: Model inputs - Gravel Pack
Gravel pack information can be entered to model an internal or external (i.e. underreamed) gravel pack. The following options are available: Cased and Perforated Well- internal or external gravel pack. In this scenario the internal gravel pack represents a conventional internal gravel pack. The external gravel pack represents where the casing has been underreamed and the perforations and underreamed area are filled with gravel. This option assumes that all other intervals in the well contain a traditional cased and perforated completion. Openhole Perforated Well- internal or external gravel pack: In this scenario the internal gravel pack represents an openhole perforated well that has been completed with a gravel pack within it (it is extremely unlikely that this case would be selected in practice, © 1990-2011 Petroleum Experts Limited
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but is provided here for flexibility). The external gravel pack represents where the casing has been underreamed, the interval has been perforated and the perforations and underreamed area are filled with gravel. This option assumes that all other intervals in the well contain a traditional openhole perforated completion. Openhole well- internal or external gravel pack: In this scenario the internal gravel pack represents an openhole well that has been completed with a gravel pack within it (it is extremely unlikely that this case would be selected in practice, but is provided here for flexibility). The external gravel pack represents a conventional external gravel pack where the casing has been underreamed and the underreamed area is filled with gravel. This option assumes that all other intervals in the well contain a traditional openhole completion. · Gravel pack permeability: the permeability of the gravel pack can be estimated using the following recommendation by Golan and Whitson (1991) US Mesh Size 40/60 20/40 10/20 8/12
Approx Mean Diameter (in) 0.014 0.025 0.056 0.080
Permeability (md) 1.2E5-1.7E5 1.2E5 5E5-6.5E5 1.7E6
· Top of gravel pack: the top depth of the gravel pack · Bottom of gravel pack: the bottom depth of the gravel pack · Gravel pack outer diameter: the outer diameter of the gravel pack.i.e. the under reamed diameter in an external gravel pack, the casing ID in an internal cased and perforated gravel pack or the wellbore diameter in an internal openhole gravel pack. · Gravel pack inner diameter: the inner diameter of the gravel pack. i.e. the diameter of the gravel screen. Note that this value is not used in the gravel pack calculations, it is only used in generating the “SPOT Well Schematic” · Calculation method: three options are presented to calculate the non Darcy flow through the gravel pack; “Golan 1 phase”, “Geertsma 1 phase” and “Geertsma 2 phase”. The “Golan 1 phase” calculation is recommended for single phase flow. The “Geertsma 1 phase” calculation is recommended for single phase flow. The “Geertsma 2 phase” calculation is recommended for two phase flow. 2.6.11.4SPOT: Model Results Enter topic text here.
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2.6.11.4.1 SPOT: Model Results - Layer Results
SPOT initially does all the calculations of corrected Lp's, skin, rates etc for each log row. For reporting purposes it then calculates representative values for the layers for some of these variables. For example it will use the results of the log rows belonging to each layer to calculate an equivalent skin for the layer. Click on the Log Results button to display the detailed results for each log row. Some of these results are at a specific FBHP so a value needs to be entered before displaying the log results.
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2.6.11.4.2 SPOT: Model Results - Log Results
This dialog displays the detailed results for each log row. Some of the data (such as rates) are calculated at the FBHP that was entered in the layer results. Notes on some of the variables are as follows:Underbalance Behrmann, Underbalance King - Recommended underbalance as calculated by Behrmann & King. Qo, Qw, Qg - rates from the log row at the entered FBHP Qo Aof, Qw Aof, Qo Aof - rates from the log row if FBHP = atmospheric pressure Qo Cum, Qw Cum, Qg Cum - the total rate from this log row plus all log rows below this log row at entered FBHP. Qo Cum Aof, Qw Cum Aof, Qg Cum Aof - the total rate from this log row plus all log PROSPER Manual
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rows below this log row if FBHP = atmospheric pressure. Beyond Zone - This is ticked if the perforation is beyond the invasion zone for this log row. Sand Production - This is ticked if the sanding model has predicted that sand has been produced for this log row.
2.6.12 Multi-Lateral Interface 2.6.12.1Network Interface 2.6.12.1.1 Motivation Multilateral wells are different than single wells because they have a variable structure. Both the number of branches and the way that they are connected is variable. Hence, a flexible network data structure is appropriate for modelling these wells. Furthermore, to provide a consistency with other Petroleum Experts products the interface has the same look and feel as the one in GAP.
2.6.12.1.2 Interface Overview The multilateral data entry screen is accessed by choosing System | Inflow Performance from the PROSPER main menu, as with the single well IPR. However, before that the multilateral option must be chosen in the Options screen, also accessed from the main menu. The User interface consists of a framework window that contains several child windows, as well as the menu and toolbar from which commands are issued. The child windows include the network windows that contain the system network drawing, the navigator window that can assist in the viewing of large networks and up to three visualisation windows, which can show the multilateral network drawn to scale from three orthogonal points of view.
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Four main components of the interface are identified, as indicated on the diagram above, which are described in more detail in the following sections: 1. Network window – the window on which the system network is drawn. 2. Navigator window – contains a full schematic that can be used to help navigation about large systems. 3. Menu bar and toolbar. The menu bar is used for issuing commands to PROSPER and the interface; it contains an abridged set of commands compared to a normal application framework window because it is a subsidiary window of the main programme. The toolbar contains menu accelerators, icons for selecting and manipulating network nodes and links, and icons for zooming or unzooming on the network window. 4. Visualisation screen – up to three windows showing front, side and top views of the multilateral network.
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2.6.12.1.2.1 Network Window
The network window is the main window on which the multilateral network is displayed and manipulated. More than one network window can be displayed at one time; this means that different views of the same system are available simultaneously, which can be of help in editing large networks. The system window is used to draw, edit, and view the system. The network nodes are represented by coloured icons. The different actions that can be performed on this window are obtained by clicking the right hand mouse button within the area of the system window, which brings up a menu. Alternatively, the same set of actions can be performed using the toolbar or the menu, which are described below. Addition of Network Nodes and Links To add an item to the system, activate the required network item type from the toolbar or by using the right hand mouse button menu. The cursor will change to indicate that a network item selection has been made. Click on the screen at the point to insert the element. A network node will be created and an icon to represent it. A label dialog will appear prompting for a name. If the element is not labelled, a default label is provided which can be edited later using the icon right hand mouse button menu. Only the four left most items in the toolbar (tie-point, junction, completion and tank/ reservoir) are nodes: links, the fifth item, are added differently by dragging between two nodes. Depending on a set of connection rules, the connection will be made or not and the correct type of link will be chosen. For example, reservoirs can only be attached to completions and the type of link is logical; in other cases the link is a piece of tubing. These rules are reviewed in the description of toolbar items. The network is hierarchical and arrows drawn on the links indicate the direction of the connections (which is normally the same direction as increasing vertical depth). Each icon is given a characteristic colour, depending on the network item it represents. The colours and items are: red (tie-point), green (junction), yellow (completion), blue (reservoir) and pink (tubing). Zoom/Unzoom To zoom or unzoom, first select the appropriate icon from the toolbar or from the right hand mouse menu, as described above. To zoom in on an area, hold the left hand mouse button while sweeping the mouse cursor over the area of interest. Alternatively, click once at a point in the system, and the programme will zoom or unzoom on that point using a fixed scaling factor (which may be adjusted using the Preferences dialog in the Preferences menu). To revert to a full system view at any time, double-click the left hand mouse button at any point in the window (except on an icon). The view will re-scale to show the whole of the system. Mask/Unmask To mask or unmask, first select the appropriate icon from the toolbar or from the right © 1990-2011 Petroleum Experts Limited
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hand mouse menu, as described above. To mask a node, click on itwith mask selected; to unmask it click on it with unmask selected. Masking removes a node from the calculation without removing it and its associated data from the network (which deleting does). Masking is useful for simulating the effect of removing or adding in completions. Note that masking a branch will have the effect of masking those below it in the hierarchy. Moving Items Select the move option from the toolbar or from the right hand mouse menu. To move a single item, place the mouse cursor above it and hold down the left mouse button while dragging the mouse cursor to the desired new location. To move a group, select an area as with the zoom option and then hold down the left mouse button with the mouse cursor in the window before dragging the whole group to a new location. Items stay selected after a group move but can be de-selected using the select option. Deletion of Items Select the delete icon from the toolbar or from the right hand mouse menu. Groups of items may be deleted by group-selecting them as above, but with the delete option chosen. NB: deletion of a node deletes the data associated with it so this option should be used with caution. To delete a pure (non data-carrying) link re-do it. Selection of Items To select an item or items, first choose the select icon (black arrow) from the toolbar or from the right hand mouse menu, the selected item will change colour. Group selections can be achieved by first selecting the select icon then drag the left hand mouse button over the area of interest. The select option is a toggle, so it can select or de-select items. Group selections can be used to turn off the selection actioned by a group move. Editing of Items If a network item carries data it has an icon associated with it and can be edited by double clicking on it provided that none of zoom/unzoom, move, delete or select are chosen. Editing of network item data is covered in the section on Data Entry. Right Hand Mouse Button Actions Utility menus will appear when the right hand mouse button is clicked anywhere in the system view. The normal menu appears when the button is clicked over an empty space. It contains the commands to add and manipulate network items as well as commands to bring up dialog screens to change fonts and icon sizes. If it is clicked over a network icon, a shorter menu will appear with a number of network item specific functions, such as the ability to change the icon size and label, and delete and select. Panning To move the view around the system, move the cursor close to the edge of the view in the direction the system will be moved. The cursor will change to an arrow. Clicking the left hand mouse button will move the system view by a fixed amount depending on the PROSPER Manual
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current scaling factor. To pan quickly, hold the mouse button down and, after a short time, the pan action will 'auto-repeat'. Popup Status Information If no toolbar (or equivalent menu item) is chosen as the mouse is moved over the network icons, a small window will appear and show basic status information for the node in question. The pop-up status window allows the validity status of a network item to be checked without entering the data entry screen. This is optional: to switch this function off go to the Preferences screen. To ‘select nothing’, toggle the currently selected toolbar or menu items, or choose the blank option from the drop-down list box in the toolbar. Changing Icon Sizes / System Fonts These functions are also available from the right hand mouse menu. See the section on menu details for more information. Other Window Actions Minimise: Click this button to minimise the window in the multilateral main window. Maximise:
Click this button to maximise the window to fill the multilateral main window.
Close:
Click this button to remove the window from the workspace.
System menu:
This contains various functions allowing the window to be maximised, minimised, moved, etc.
2.6.12.1.2.2 The Navigator Window
This window can be used to aid in navigation about a large system. It will always consist of a system schematic that is independent of any zooming on a system window. In addition to the network, it contains a tracking rectangle that encloses the portion of the system currently under view in the system window. The tracking rectangle has two functions. If the focus is currently on a network window, this rectangle surrounds the area of the network that that view is displaying. Alternatively, the rectangle may be used to create new views of the network if the navigator window is currently in focus. When the mouse is moved over the rectangle, the cursor changes to allow resizing of the rectangle. In this way, the navigator window facilitates creating views in areas of interest. Double-clicking the left hand mouse button in the area will create a new system view displaying the selected area, although resized to preserve a sensible aspect ratio. Right Hand Mouse Button Menu © 1990-2011 Petroleum Experts Limited
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Clicking the right hand mouse button within the navigator window will produce a utility menu. This contains the following functions: Navigator On Top: By default, the navigator is always on top of all system views. This can be changed by selecting this item from the menu. Hide Window: The navigator can be hidden using this option and, once removed, will not appear in subsequent sessions until reopened from the Window menu. The navigator can also be hidden by clicking on the cross button at the top right hand corner of the window or by using the Window menu option. New Window: Another way of producing a new view (see above). Icon Sizes: Invokes the Icon Sizes dialog (see below).
2.6.12.1.2.3 Toolbar Details
The toolbar is located below the main menu at the top of the main window. It consists of a row of icons (described below) which act as accelerators to the menu functions accessed from the Tools menu or most of those called from the right hand mouse button in the network window. The functions of the various buttons are described below. A quick description can be gained for a given button by holding the mouse cursor over the button for a moment. A small yellow box with a short description will appear. Network Item Set-up The functionality of the network items buttons is duplicated in the drop-down list: a selection from this list will cause the appropriate button on the toolbar to be shown as depressed. When a network item button is selected, the cursor, when over a system window, will be drawn to represent the current selection. Click once on the system window to cause a new node of the required type to be created at the chosen point. A label dialog will appear to allowing the node to be labelled; leaving the label blank results in default node naming. This can be edited later by clicking the right hand mouse button on the icon created. Connections between nodes are created by choosing the ‘Link’ button and holding down the mouse left hand button whilst dragging between the nodes. There is a connection hierarchy, which is represented by the branching of a parent branch into one or more child branches, in the same way that the multilateral well branches out physically. Indicate the direction of the hierarchy for junction-completion or completioncompletion connections by the order in which they are joined up. Tie-point. This is the node for which the IPR is solved and is located at the top of the system (in vertical depth and hierarchically). Hence, the tie-point
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can only be a start point. Junction. The main purpose of the junction is to be a branching node. It can only have one link into it (from a tie-point, completion or other junction) but any number coming out. Completion. This contains both tubing and completion information. It is attached below a tie-point, junction or another completion. It can only have one link into it and branches out to either a junction or another completion. It can also be logically attached (no direction implied) to any number of reservoirs (but at least one). Tank/reservoir. This represents a reservoir source and is logically attached to any number of completions (but at least one). Link. Connecting to a junction, the link becomes a tubing node and contains data. Going into a completion, the tubing information is in the completion and the link is ‘blank’ only indicating the hierarchical relationship between the nodes it connects with an arrow. Finally, when connecting a completion and a reservoir, the link is logical and not hierarchical. Note that re-doing a link between two nodes will delete it. 2.6.12.1.2.4 Network Manipulation
Zoom in/out. When 'zoom in/out' is selected, a zoom can be achieved either by clicking the mouse on the system window, which will zoom in/out a fixed amount and set the centre of the view to the position clicked. If ‘zoom in’ is selected, sweeping an area with the mouse will zoom in on the area selected. The aspect ratio will be retained when an area zoom is performed. Mask/Unmask an item. After masking is selected specific items can be removed from the network for calculation purposes without deleting them. This is particularly useful for seeing the effect of removing a completion item. Delete a node. After this is selected, the node may be deleted by clicking on the item in the system window. The icon automatically becomes unselected following a deletion to prevent accidental deletion of further nodes. To delete a pure (non data-carrying) link re-do it. Move a node. After this is selected, a node may be moved by clicking on the item in the system window and then, with the mouse button depressed, dragging the item to the new position. A group of nodes may also be selected and moved. Select a node. After this is pressed, a node may be selected/de-selected by clicking on the item in the system window. The item will reverse its colour to indicate selection/de-selection.
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2.6.12.1.2.5 Menu Details
Finish Done – exits the screen but validates the multilateral structure and data first. If the structure is not valid a warning message appears providing the opportunity to remain in the multilateral screen. One can exit the data screen, however, the data are marked invalid. Cancel – leaves the multilateral screen, restoring the network to its state at the start of the edit session. Tools These are equivalent to items to the right of, and indeed inside, the drop-down list box in the tool bar and have been explained above. Analyse This menu contains options to plot and report the IPR results in a similar way to those in the Single Well IPR. The multi-lateral is treated as one reservoir model option, such as the multi-layer with dP friction loss. There is also a Calculate option, which brings up the dialog in the following figure.
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The Calculate screen gives the option of calculating one IPR point or a curve. In the former case pressure can be calculated from a rate or rate from a pressure. In the latter case, pressure is calculated for a range of rates up to the AOF, as with other IPR calculations. From this screen it is possible to specify the number of IPR points (maximum 20) and the minimum pressure to calculate to. These are to help speed up calculations if appropriate. Results of the points for curve calculation will be reported at the bottom section of the screen. Also, having a bearing on calculation speed is the switch between infinite and finite conductivity modes of calculation. In the latter case the pressure drop in the tubing is taken into account. Before carrying out the calculation, the network structure is validated and any errors are reported in the white list box in the middle section of the screen. If the structure is not valid the calculation is not carried out. The Details button is used to display pressure and rate-related parameters with respect to the measured and vertical tubing depths of each branch. During a calculation, diagnostic information is reported to the list box. Also, a Cancel button is placed above the Calculate button to allow stopping the calculation. The buttons to the left of the list box perform the functions in the Analyse menu, except Help, which brings up this section. The push button Done exits the screen. Visualise These items are dealt with in the section on visualisation screens. © 1990-2011 Petroleum Experts Limited
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Preferences The preferences dialog is gained from the Preferences item of the frame window menu. It allows customisation of a set of User-interface variables for subsequent PROSPER sessions. The following options are available: ·
Enable Flyover Status Information. If this is checked then a status box appear as the mouse is moved over the network item icons.
·
Auto-repeat delay when panning. When panning, the left-hand mouse button may be held down to ‘auto-repeat’ the action. The value given in this field represents the time (in ms) before the auto-repeat action starts from when the mouse button is clicked.
· Fraction of screen to pan per click. This represents the ‘resolution’ of panning. ·
Zoom/unzoom factor. A single click in a system window while the zoom or unzoom icons are active results in a fixed scaling to be applied to the view, while the centre of the view is changed to the position in which the mouse was clicked. The value entered in this field is the fixed scaling factor, and as such should be greater than one.
·
Background. The background bitmap that is displayed on the background of the main window (by default this is a PE logo with contact information) may be changed. Select the required bitmap by pressing the button to the right of the field. The bitmap will only be loaded after shut down and restarting the multilateral main screen.
Output Printer Setup - to set up the printer if not already done. Print - prints the current child window as a hard-copy, metafile or to the clipboard, whether a network window or a visualisation screen. Window Menu · New Window. This creates a new system view. The new view is zoomed out to include all the components. · Close All. Shuts down all system windows in the application. · Cascade. This reorganises the system windows into a ‘cascade’. · Tile. Tiles the system windows. · Toggle toolbar display. This will remove the toolbar if it is currently displayed, and vice-versa. If the toolbar is not displayed, toolbar commands can be accessed via the right hand mouse button on the system view window. · Toggle navigator display. Displays or hides the navigator window. Below this is a list of currently active system windows. The current focus window may be changed by clicking on one. Help
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Brings up this information on the network interface. Other Items Apart from the preferences it is possible to change other aspects of the User interface: namely font and icon sizes. Network Fonts Fonts used in the network drawing may be changed. To do this, select the Fonts option from the menu obtained following a right hand mouse button click in the system window. This will bring up a font selection dialog. Select the required font and style and press OK. The new font will be applied to all network drawings and also to labels in the visualisation windows. Icon Sizes The sizes of the icons used to represent the network nodes can be changed. Select the Icon Sizes option from the menu obtained following a right hand mouse button click in the system window. The following dialog will appear:
The dialog consists of a slider with a data entry field, which contains the current icon size (this defaults to 50 out of an arbitrary 0 – 100 range for a new file). Change the icon size by adjusting the slider or entering a new size in the entry field. Check the ‘Automatic Update’ box to update the system window with the new size as the slider is moved. When the new icon size is entered, click on This View or All Views. In the latter case the change will be applied to all network windows. In the former case, only the currently active network view will be changed. The new icon size will not be saved; i.e. all changes will be lost when the current file is exited. 2.6.12.1.2.6 Visualisation Screens
These screens supply three 2-D views (front, side and top) of the 3-D multilateral object. The salient visual objects (tie-points, junctions, tubing, completions and reservoirs) are drawn symbolically but they are spaced to scale. The screens are updated whenever a network item is edited and has a valid data set and whenever an item is deleted or becomes invalid. The visualisation objects are given the same colour as their equivalent network objects (e.g. blue for reservoirs), and are identified by the same © 1990-2011 Petroleum Experts Limited
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labels as in the network structure. The geometry used is left-handed Cartesian. It is assumed that the positive x axis is along the direction of zero azimuth, positive y is at 90 degrees and positive z is in the direction of increasing depth. The front view shows the (x, z) plane, where y is increasing going into the screen and consequently positive z corresponds to moving down the screen and positive x corresponds to moving to the right. The side view shows the (y, z) plane, where x increases coming out of the screen, z increases going down the screen and y increases going to the right. The top view shows the (y, x) plane where z is increasing going into the screen, x increases going down the screen and y increases going to the right. The screens are brought up using the Visualise menu. One of the three views (front, side and top) or all of them can be activated using the appropriate menu command. If all the views are shown then they are tiled with any active network windows. The title bar of each view window shows the extent of the network for the plane in question. The coordinates are shown with respect to the start of a (hypothetical) straight tubing, which enters the tie-point in the direction of zero azimuth and has measured and vertical depths equivalent to those of the tie-points. In a similar way to the network window one can pan across a visualisation window by moving the mouse cursor close to one of the window edges and clicking on the left button when the panning cursor appears. The fraction of the screen traversed and the auto-repeat delay are controlled by the same options as in the network window (chosen from the Preferences dialog). Right-hand Mouse Button Menu Using the right hand mouse button on a view screen one can choose to display the coordinates of any of the visual objects. The displayed coordinates can be written over one another, it is sometimes better to view them separately. By default, the reservoir depths are displayed at the start of a session. The next group of functions from this menu contains zoom, unzoom and restore. The latter option resets the scale factor and the view origins (which can be moved by panning) to the default values. The zoom factor is the same as that used for the network window and is set in the Preferences dialog. Finally, the way the picture is drawn can be altered. Normally, the zooming not only changes the extent of the drawing seen but also magnifies the objects (network items and text) drawn. Switch off the magnify mode if zooming into a cluttered area as this will allow more objects to fit in. Also, the network drawing is normally scaled to fit the window, irrespective of the relative extents to the two axes. Choosing the ‘draw to scale’ option stretches the drawing in the direction with the greater physical extent (so it no longer fits in the window).
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2.6.12.2Data Entry 2.6.12.2.1 Overview The data associated with any network item is accessed by double-clicking on its icon when none of the network manipulation options (zoom/unzoom, delete, move and select) have been chosen. This brings up a screen with editable data fields in it. Apart from the tie-point and junction data screens, the main data entry screen for each node is similar to that of the single well main data entry screen (see Section 7.1). However, the reservoir data input child screen does not have any tab buttons in it. The main data screens differ from the single well case in the action buttons: only the leftmost group - Done, Cancel, Reset, Validate and Help - are available. Their function is the same as in the single well case. Hence, the differences between the single well IPR data entry and the similar multilateral ones lie in the model selection and data input child screens. Given the hierarchical nature of the network, editing a parent branch causes the starting points (e.g. depths) of child branches to be initialised. Those data fields that are initialised from outside a particular network item are set read-only (coloured cyan) when the screen to edit that net item is brought up. Hence, in order to edit a net item and fill it with valid data it is normally necessary to have edited the parent branch first. However, it is not a requirement to edit the network in hierarchical order as any child net item can be filled with invalid data and saved before editing its parent. Another difference from the single well IPR is that in each screen, on the right hand side, there is a list box containing a drawing of the network where the data carrying nodes are sorted hierarchically, by type or alphabetically according to a right-hand mouse button menu selection. By clicking on the line corresponding to a node the given screen is closed and the screen belonging to the node clicked on is opened.
2.6.12.2.2 Tie-point and Junction Data The tie-point data consist of a measured and vertical depth, with an implied azimuth of 0 °. The junction data are the same but are read-only. A junction must always be hierarchically below another network item, so its data are entered automatically from its parent. As mentioned earlier a junction mainly forms a branching point.
2.6.12.2.3 Tubing Data Model Selection Screen The model selection screen for tubing has options to select horizontal and vertical correlations, choke models, flow types (tubing or annular) and correlation threshold details. None of the options affect the general format of the data input screen but the flow type affects the details of the equipment tabbed dialog in the data input screen. © 1990-2011 Petroleum Experts Limited
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Data Input Screen There are two tabbed dialogs in this data input screen, which allow the entry of a deviation survey and equipment descriptions. These dialogs contain tables very similar to the ones encountered by selecting System | Equipment from the PROSPER main menu and then the Deviation Survey and Downhole Equipment push buttons. In the case of the deviation survey there is an additional azimuth entry.
2.6.12.2.4 Completion Data The completion data screen represents tubing and a completion. Hence, it is a superset of the tubing data screen and is the same except for one extra tabbed dialog in the data input screen, for completion data. This dialog has fields in it similar to the single well IPR Wong-Clifford model for describing a deviated completion (completion zone start and end measured and true depths) as well as a field for entering a local (mechanical/geometric) skin value. There is a drop-down list box in the fifth column, which allows the skin to be calculated using the Karakas & Tariq method. The selection of ‘Karakas and Tariq’ enables the push button in the last column, which brings up an appropriate data entry screen when clicked upon with the mouse left button. On entering valid data and exiting that screen with Done the skin value is calculated and entered in the skin data column.
2.6.12.2.5 Reservoir Data Model Selection Screen The model selection screen contains a model selection list box for selecting a Darcylike reservoir model as well as several data entry fields for entering PVT and geometrical data used by all the models. Data Input Screen The data input screens contain a single sub-dialog pertaining to the model chosen. These are similar to the equivalent models in the single well case. Consistency Validation Beyond the consistency enforced by the validation of individual network items as they are edited and the automatic entry of some child branch data from parents, there are other checks carried out on a complete structure whose nodes are individually valid: · · ·
There must be no more than one tie-point in a network; other loose items are ignored. The top node must be a tie-point. All branches must end in a completion; completions must be attached to at least one reservoir.
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Reservoirs should not overlap in depth (in the current model they are assumed to be layers).
2.6.12.3Example of How to Set Up a Simple System 2.6.12.3.1 Introduction The purpose of this exercise is to enter some geometrical data for the simple multilateral in the following ‘back of an envelope’ sketch and then visualise it using the V isualise menu. It is assumed that the fluid selected is ‘Oil and Water’ and the units system is oilfield units. We will also show the procedure for running a calculation, to which purpose some default PVT and geometric data should be entered in the reservoir screens. The multilateral has two branches, with one branch having an azimuth of 170° with respect to the other. The zig-zag lines indicate completions and the areas between the horizontal straight-lines are layers/reservoirs. Note that one tubing branch contains two completions and goes through two reservoirs. This will be modelled as one completion node and logically attached to two reservoirs. The point at (12000, 10000) feet will serve as a tie-point.
(0, 0) = (measured depth, vertical depth)
10000 feet
(12000, 10000) (12100, 10020) (12200, 10020)
Kh = 100 mD
(12400, 10100) 10100 feet Azimuth = 170 deg. Azimuth = 0 deg.
10200 feet Kh = 50 mD
(13000, 10210)
(13000, 10220) (14000, 10220)
(14000, 10280) 10300 feet
Sketch of a Multi-lateral Network
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2.6.12.3.2 Place the Nodes in the Network Window The nodes needed are one tie-point (as always), a junction (to model the branching), two completions (although there are three zones, the data for two will be contained in one node), and two reservoirs. Each node can be selected from one of the following: 1. Using the Tools | Add Item option in the frame window menu. 2. Clicking on the appropriate icon in the toolbar. 3. Selecting the required option from the drop-down list box in the toolbar. 4. Using the right hand mouse button menu. Once the appropriate node addition option has been selected, click somewhere in the blank network window to create an icon. Allow the programme to attach a default label to the node by not entering one. Do this for all the required nodes listed above.
2.6.12.3.3 Connect the Nodes Before doing the connections, space the nodes and arrange them in height order with the tie-point at the top, followed by the junction, followed by the completions and put the reservoirs at the bottom. Keep the completions and reservoirs at the same horizontal level with C1 and R1 on the left. Now select the link option and drag the mouse cursor (with the left button down) between the following icons in order to make the connections: TP1-J1, J1-C1, J1-C2, C1-R1, C2-R1 and C2-R2. Note that between the tie-point and the junction a tubing icon is drawn to indicate that this link contains tubing data. The order of the connections J1-C1 and J2-C2 are important for the reverse would imply that the completions were above the junction hierarchically. 2.6.12.3.4 Enter the Data To enter data, double-click on an icon to bring up a screen. Tie-point (TP1) Enter 12000 feet and 10000 feet for measured and vertical depth respectively and then click on Done. Tubing (T1) Make sure that ‘Flow Type’ is ‘Tubing Flow’ on the model selection screen and a suitable value (0.354 ft) is entered for well-bore radius. Then leave the model selection screen with its other defaults and enter the data input screen using the button Input Data in the top right hand corner. In the ‘Deviation’ tabbed dialog enter the three numbers: PROSPER Manual
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in the white boxes in row 2. Now enter the ‘Equipment’ tabbed dialog by clicking on that tab. In row 1 choose ‘Tubing’ from the drop-down list box and then enter the four numbers: 12100
0.7
0.0006
1
in the white boxes in row 1. Click on Done to finish. Junction (J1) The co-ordinates (12100, 10020) should already be entered in the junction net item. Completions (C1 and C2) The model selection screens should be as with T1 except a Dietz shape factor should be entered (e.g. 31.6). The other screens should have their white spaces filled as follows. In the equipment screens the first row drop-down list box should always be set to ‘Tubing’. C1 Deviation 13000 10210 14000 10280 C1 Equipment 14000 0.7 C1 Completion Info. 13000 14000
170 170
(row 2) (row 3)
0.0006
1
(row 1)
10210
10280
1
(row 1)
C2 Deviation 12400 10100 0 (row 2) 13000 10220 0 (row 3) 14000 10220 0 (row 4) C2 Equipment 14000 0.7 0.0006 1 (row 1) C2 Completion Info. 12200 12400 10020 10100 13000 14000 10220 10220
1 1
(row 1) (row 2)
Reservoirs (R1 and R2) For both reservoirs select ‘Darcy’ as the model. The edit fields for entry of the data for this model should appear on clicking on Input Data. In order to agree with the specifications of the sketch enter the following data: R1 Reservoir Top Depth: 10200 feet Reservoir Permeability: 50 md Reservoir Thickness: 100 feet R2 Reservoir Top Depth: 10000 feet © 1990-2011 Petroleum Experts Limited
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Reservoir Permeability: Reservoir Thickness:
100 md 100 feet
The other fields in the model selection and data input screens (for both reservoirs) should be entered with some reasonable numbers. For example: pressure (5000), temperature (200), salinity (150000), water cut (15), GOR (800), gas gravity (0.9), oil gravity (30), vertical permeability (10) and drainage area (500).
2.6.12.3.5 Visualise / Calculate Choosing Visualise |Front should show a picture similar to the one in the sketch above. Also, providing the data has been entered correctly, the network structure should be valid; this can be verified by going to the screen brought up by the Analyse| Calculate menu command and choosing one of the calculations. Note that this exercise is not meant to represent a real case but only a reasonable set of data that the program can process. The comments below will describe what calculations are performed when a system calculation needs to be performed and the Multilateral model is used. a) PROSPER uses the already generated IPR with “Analyze | Calculate | Calculate” to get the intersection between VLP and IPR first. b) The solution FBHP from step a) is then used to refine the solution rate by performing a single point calculation like ““Analyze | Calculate | Calculate | Calculation “One Point” and this point uses the solution flowing bottom hole pressure This means that whenever a change is made, the “Analyze | Calculate | Calculate” routine needs to be re-run before performing a system calculation so that an updated IPR can be used.
2.7
Artificial Lift Data Input This section describes how to enter the description of artificial lift equipment in a well for calculating a systems analysis. The Design section describes how to select suitable gas lift, ESP, HSP, PCP and jet pump equipment for new or existing wells.
2.7.1 Continuous Gas Lift Input Data This option is available only when Gas Lift has been selected as the lift method in the Options menu. To analyse an existing gas lifted well, the equipment details must be entered in the Gas Lift Data section that becomes viewable after selecting gas lift from Options. To design a new gas lift installation, skip the System Gaslift data menu and PROSPER Manual
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go directly to Design Gaslift Design (New Well). Note that the gas lift design section has been revised to give users greater flexibility in choice of design methods. The required input depends on the choice of casing pressure calculation method. These are the options available that can be selected in the general options: ·
No Friction Loss in Annuls No flowing pressure losses occur in the annulus. A static gas gradient in the casing is assumed. This model should be used for the majority of gas lift installations.
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Friction Loss in Annuls The friction pressure drop in the casing is calculated. Input of both tubing O.D. and casing I.D. is required to define the annulus geometry.
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Safety Equipment Friction pressure losses are calculated in the surface piping, tubing/ casing annulus and an annular safety valve where fitted.
To analyse an existing installation, the gas lift details that need to be entered will depend upon the particular gas lift method that has been selected. Firstly select the gas lift system type on the Options menu, then enter the gaslift data by selecting Gaslift data on the System menu. Enter the required lift gas composition data. It is possible to model CO2 or N2 as the injected gas. For example, to model CO2 injection enter Gaslift Gas Gravity = 1.53 and Mole percent CO2 = 100%. Select one of three gas lift methods available. The methods currently available are:
2.7.1.1 Fixed Depth Of Injection When this method is selected, only the depth of injection will be asked for. Ü
The program assumes that the casing pressure is sufficient to inject lift gas at the specified depth to achieve the GLR Injected or the Injected Gas Rate.
The GLR injected can be subsequently overwritten with entered calculation sensitivity variables. If the GLR injected is unknown, leave it set to zero. The GLR to inject is set using Sensitivity variables GLR injected or Injection gas rate in the Calculation section.
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GLR/Rate ? It is possible to select whether to use by default GLR Injected or Injected Gas Rate as mode of gas injection. For example, if one selects use GLR Injected as method, then the program will use by default the value of GLR injected entered in the same screen above. If instead before any calculation one enters the gas lift gas (as GLR injected or gas lift gas injection rate) as sensitivity parameter, then the mode selected in the GasLift Input Data will be overwritten.
2.7.1.2 Optimum Depth of Injection When this method is selected enter the maximum depth of injection, the dP across the gas lift valve and the top casing pressure and PROSPER will iterate to calculate the optimum injection depth for changing well conditions.
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For the Gas lifted (safety equipment) option, the compressor discharge pressure is requested instead of the casing pressure. Ü
Use Optimum Depth of Injection to evaluate the potential increase in production due to gas lift without the need to perform a detailed design and spacing the unloading valves.
2.7.1.3 Valve Depth Specified Enter the measured depth of the gas lift valves. The program automatically calculates which valve opens for particular liquid and gas injection rates.
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If a gas lift design has already been done, or the mandrel depths have been entered for a Gaslift QuickLook Calculation, the valve details can be copied across using the T ransfer button. Ü
The Casing pressure entered should be the available injection system pressure for the current operating conditions If calculating sensitivities for a new casing pressure operated design, always subtract the dP to close valves for each unloading valve above the operating valve from the design casing pressure.
2.7.1.4 Gas Lift (Safety Equipment) For the Gas Lifted (safety equipment) option, the annular safety valve pressure losses are calculated using the valve depth and ‘bean diameter’ entered on the System Gaslift Data screen as follows:
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The safety equipment data can be entered by accessing the Safety Equipment button in this screen. The details of the surface injection system are used to calculate the casing head pressure as a function of gas injection rate and compressor output pressure. Frictional losses in the annulus are taken into account when calculating the casing pressure at each gas lift valve depth. The safety valve pressure loss is clearly seen on the following gradient plot:
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2.7.1.5 Gas Lift (Allow injection in Pipe Line above wellhead) This option implemented allows to model gas injection in a pipeline. To enable this option, select Pipeline Only in the Options Summary and Gas Lift in the Artificial Lift method. To specify the position of the gas lift valve, in the surface equipment data select this feature in the equipment type combo box , as shown below:
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And in the Gas Lift Data enter the properties of the gas and the GLR injected:
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It is possible to model CO2 or N2 as the injected gas. For Example, to model CO2 injection enter the Gaslift Gas Gravity as 1.53 and enter Mole percent CO2 as 100%.
2.7.2 Intermittent Gas Lift If intermittent gas lift is selected as artificial lift method, the following input data are required:
Surface injection pressure: this is the gas lift injection pressure at surface Injection depth: depth of the injection valve Gas lift gas gravity: gravity of the injected gas lift gas Valve port size: size of the injection valve Water Cut: water cut of the produced well stream Tubing Liquid level: depth of the liquid in the tubing to be lifted
2.7.3 ESP Input Data If Electrical Submersible Pump has been selected as the well lift method on the O ptions screen, then Electric Submersible Pumps. will be active on the System input menu. If a new ESP design is being performed, the equipment has not yet been sized, so skip the ESP Input section entirely and move directly to Design on the main PROSPER tool bar. For analysis and optimisation of an existing ESP installation, enter PROSPER Manual
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the data on the ESP input data screen as requested:
The Pump wear factor is used to account for deviation from the manufacturer's published performance curves due to wear etc. Ü
For example, entering 0.05 causes the program to scale the pump head curves down by 5% (i.e. head is 95% of the database value). Entering 0 causes the program to use the database curves directly. A negative number can be entered to simulate a particular pump that performs better than the database curve. Note: to be able to enter negative wear factors, modify the range of validity of the wear factor parameter in the Units section. To do that, access the menu Units/Units and enter for the Pump Wear Factor a Minimum Validation value equal to -1 (fraction):
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When a downhole gas separator is run, the GOR of the oil above the separator will be lower than the produced oil GOR. Depending on the completion, the separated gas is produced up the annulus or a separate tubing string. Both casing I.D. and tubing O.D. are required to be input on the System Equipment Downhole Equipment.
2.7.4 HSP Input Data If Hydraulic Drive Downhole Pump has been selected as the well lift method on the O ptions screen, then Hydraulic Submersible Pumps will be active on the System input menu. If a new HSP design is being done, the equipment has not yet been sized, so skip the HSP Input section entirely and select Design from the main PROSPER tool bar. For analysis and optimisation of an existing HSP installation, enter the data on the HSP input data screen as requested:
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The Pump wear factor is defined as in the ESP pumps, as seen in the previous section. Turbine speed is assumed to be the same as the Pump speed. The % Power Fluid of Reservoir Fluid defines what fraction of the total produced liquids the power fluid represents. Ü
A figure of 100% means that the amount of power fluid used to drive the turbine is the same as the amount of produced reservoir fluids.
2.7.5 Progressive Cavity Pumps If the PCP option has been selected as the well lift method on the Options screen, then the progressive cavity Pump option will be active on the System input menu.
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For analysis and optimisation of an existing PCP installation, enter the data on the PCP input data screen as requested: If a new PCP design is being done, the equipment has not yet been sized, so skip the PCP Input section entirely and select Design | Database | PCP from the main PROSPER menu to enter the given pump performance data.
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The Optional Data input section in the above screen shot is used to calculate the frictional torque and shaft axial load. If no data is input in the optional data section, results will not be displayed for the given parameters.
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The "Optional Data" may be proprietary, and can be obtained from the given pump manufacturer.
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To select the correspondent pump and rods, the pump database must be set up first. The section devoted to the PCP design will describe how to enter the correspondent pump and rods database.
2.7.6 Coiled Tubing Gas Lift This option is available only when Gas Lift with coil tubing is selected as the lift method in the Options menu. To analyse an existing installation, enter the data in the Coiled Tubing Data section, as shown below:
Two lift methods are available: Specified Injection Depth and Optimum Injection Depth. Please refer to the Gas Lift section above for further details.
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2.7.7 Diluent Injection This technology is used to enhance the production of heavy, viscous crude oil, in some cases making previously not producible hydrocarbon reserves economically recoverable. With diluent injection, the light hydrocarbon diluent reduces crude viscosity and improves its flow characteristics. When Diluent injection is selected as Artificial Lift Method, Diluent Injection is active in the System menu. The only input data required are injection rate and depth:
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2.7.8 Jet Pumps If Jet Pump has been selected as the well lift method on the Options screen, then Jet Pumps will be active on the System input menu. If a new Jet Pump design is being done, the equipment has not yet been sized, so skip the Jet Pump Input section entirely and select Design from the main PROSPER tool bar. For analysis and optimisation of an existing Jet Pump installation, enter the data on the input data screen as requested:
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In this section the User has to select the Pump and enter specify its position and maximum size along with injection rate and pressure. The loss coefficients are also required. These coefficients are a measure of the energy loss due to the friction in the above quoted sections of the pump. The coefficients are provided by the Jet Pump manufacturers.
2.7.9 Multiphase Pumps When Multiphase Pump (FRAMO Pumps) has been selected as the well lift method on the Options screen, to perform the analysis and optimisation of an existing FRAMO Pump installation, enter the data on the input data screen as requested:
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The Pump Wear Factor is defined in the same way as in the ESP pumps. Please refer to that section for details. Other input data are the power available, the pump configuration (single pump or pumps in parallel) and the pump model.
2.7.10 Sucker Rod Pumps If Sucker Rod Pump has been selected as the well lift method on the Options screen, then Sucker Rod Pumps will be active on the System input menu. If a new SRP design is being performed, the equipment has not yet been sized, so skip the Sucker Rod Pumps Input section entirely and move directly to Design on the main PROSPER tool bar. For analysis and optimisation of an existing SRP installation, enter the data in the Systemú Sucker Rod Pumps input data screen as requested:
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The input data screen is directly connected to the database for the Sucker Rod Pumps.
2.8
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· Fine adjustment of the model parameters to enable well models to reproduce observed data · In case of artificial lift, system diagnostics and troubleshooting A properly matched model is a pre-requisite for accurate performance prediction. Ü
The Quality Control exercises like Correlation comparison are based on what is possible according to the principles of fundamental physics.
The Matching menu offers the following calculation options: VLP / IPR Matching This option enables the User to tune the well bore multiphase flow correlations to fit measured downhole pressures and rates. Up to 1000 well tests can be stored and used for matching purposes. Once the VLP is matched, the IPR can be adjusted to match observed rates and pressures also. Gradient Matching Existing correlations can be modified using non-linear regression to best fit a gradient survey. Comparison of the fit parameters will identify which correlation required the least adjustment to match the measured data. Ü
This should be used only if for a given rate more than one measurement is available along the production string.
Pipeline Matching The program uses actual wellhead and manifold pressures together with temperature data points to match surface pressure drop correlations. Separate screens allow the match parameters to be viewed and the best match selected. Correlation Comparison This is the primary step in quality control of measured well test data. This option allows pressure gradient plots to be generated with different correlations to be compared with measured gradient survey data. The comparison enables the User to: - Understand if the measurements “make sense”, that is to say, violate or not the principles of physics - Select the flow correlation that best fits the experimental measurement Correlation Comparison is a fundamental step in the quality check of the model. QuickLook This feature is active only if an artificial lift method (Gas Lift, ESP or HSP) is selected. It allows calculation of the pressure gradient in an artificially lifted well for a quick check PROSPER Manual
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of lift performance. For gas lifted wells, valve opening and closing pressures are calculated to permit troubleshooting gas lift installations. For ESP and HSP wells, the performance of the ESP and HSP can be checked. Correlation Parameters The tubing and pipeline match parameters can be inspected reset or entered by hand using this menu option. This capability is useful for troubleshooting, or to input match parameters determined previously. Correlation Thresholds This option allows the User to specify a threshold angle for both tubing and pipeline correlations at which the program will automatically change to another (specified) correlation. This option will enable vertical risers in sub sea completions to be modelled more accurately. Ü
VLP Matching is not available for Enthalpy Balance temperature model applications. For Enthalpy Balance applications requiring VLP matching, use the Predicting Pressure Only, or the Rough/Improved Approximation temperature model, to perform the correlation matching. Once the matching operation has been completed, return to System and re-activate the Enthalpy Balance option. The VLP match parameters will be carried over.
2.8.1 VLP/IPR Match and Quality Check This feature enables the User to adjust the multiphase flow correlations to match flowing bottom hole pressure surveys or production logging runs. Up to 1000 pressure tests can be stored and used for matching. VLP/IPR Match allows data to be matched over a range of rates as well as depths.
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The Gas Oil Ratio is the solution GOR. If the reservoir is under-saturated, there is no free gas production at the sand face and the GOR free should be set to zero. The Gas Oil Ratio can also be entered as Total GOR (Solution + Free GOR). In this case the GOR Free can be entered as nil. The program will determine how much gas is in solution and how much in the free phase according to the PVT.
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The required input data are: Test Point Date and Comment
A comment can be entered for the test. Also, each test can be associated to a date stamp
Tubing Pressure
Head Flowing pressure for test rate entered.
Tubing Temperature
Head Flowing temperature at test rate. Usually has only a minor effect.
Water Cut
Test water cut. (WGR for Gas or Condensate)
Rate
Enter either Oil or Liquid rates as selected. (Oil Wells Only)
Gauge Depth
Depth of measured pressure data point.
Gauge Pressure
Measured pressure at test flow rate.
Reservoir Pressure
Pressure of the reservoir when the test was taken. This field will not be displayed if the IPR model in use is MultiLayer or MultiLateral
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GOR
Solution GOR (Oil) , CGR (Gas) or Separator GOR (Condensate)
GOR Free
Free gas production from a gas cap or injection breakthrough. The measured total GOR during the test (including the tank gas) must equal GOR + GOR Free. (Oil Well Only)
Gaslift Gas Rate
Rate of lift gas injection (gas lifted wells only).
Injection Depth
Depth of operating valve (gas lifted wells only) .A good bottom hole pressure match will not be obtained if an incorrect injection depth is used.
Operating Frequency
ESP lifted wells only
Pump Wear Factor
ESP Lifted wells only
Pump Pressure
Intake ESP Lifted wells only
Pump Discharge ESP Lifted wells only Pressure The Test Point Date and Comment fields are provided to allow the optional entry of notes to identify the match data set. Examples would be test date, source of pressure data, comments on test quality etc. This input screen has a number of features to simplify data manipulation. The selection buttons on the left hand side are used to select data points for further editing. Hold down the Ctrl key and click the required buttons to select multiple points. Copy copies the selected points into memory and onto the Windows clipboard. Click the selection button of the desired destination and click Paste to copy the data to the new location. I nsert shifts the data down to make room for new entries. The Delete button deletes the selected records. Data from this table can be copied to or from the Windows clipboard. Therefore, test data can be read in from a Windows based spreadsheet by first copying it to the clipboard, and then pasting it directly into the table. Bad or inconsistent data points occasionally prevent the program obtaining a good match. The Disable button causes a selected data record to be ignored in the matching process. Disabled records are dimmed in the VLP matching screen. Disabled points can be re-included in the matching process by first selecting the point and clicking on E nable. By sequentially disabling suspect data points, potentially inaccurate test points can be identified and eliminated from the match.
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If the temperature prediction method is ‘Rough Approximation’, the User can now use the ‘Estimate U value’ button to estimate the overall heat transfer coefficient for the selected well test. The procedure is: · · · ·
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The User can now use the ‘Correlation Comparison’ button to transfer the selected well test data to the correlation comparison section. The procedure is: · · ·
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Click on the button to the left of the well test data that we wish to estimate the overall heat transfer coefficient. Click on the ‘Estimate U value’ button PROSPER will estimate the overall heat transfer coefficient that matches the wellhead temperature of the well test. The User can then go to the Geothermal Gradient section to change the overall heat transfer coefficient value.
Click on the button to the left of the well test data that we wish to perform correlation comparison on. Click on the ‘Correlation Comparison’ button PROSPER will bring us to the correlation comparison screen and at the same time, populate the correlation comparison screen with the selected well test data.
For each well test it is possible to enter a date stamp and the reservoir pressure at the time of the test. This feature can be used to store the actual reservoir conditions and allow the User to get back in time and check old tests.
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Accessing QuickLook When Gas Lift, ESP, or HSP artificial lift method is in use, from the VLP/IPR matching screen it is possible to access the QuickLook section
New!!! Adjust IPR: After matching the VLP, it is possible to solve the system for reservoir pressure in automated fashion. The algorithm will estimate the reservoir needed to match the well test. The user will have to make an engineering judgment about the adequacy of the mathematical solution.
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2.8.1.1 VLP Matching To compute the VLP match, click Match VLP to display the VLP matching screen. Select the correlations to match or just click All to match all correlations. An example screen is shown below:
Click the Statistics button to examine the match parameters as shown on the example screen below:
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should be done with extreme caution and only if previous work on similar wells has yielded consistent match parameters or to apply match parameters for the same well in a different PROSPER application. PROSPER uses a non-linear regression to tune the VLP correlations to best match the measured data. It does this by calculating a pressure traverse using a correlation and determining the error between measured and calculated pressures. The gravity and friction terms of the pressure loss equations are then adjusted and the process repeated until the measured and calculated results agree within 1 psi, or 50 iterations have been completed. Notes on Matching Parameters Parameter 1 is the multiplier for the gravity term in the pressure drop
Ü correlation
Parameter 2 is the multiplier for the friction term. If all the data are consistent, these two parameters should be within a ±10% tolerance from the unity. If PROSPER has to adjust Parameter 1 by more than +-10%, then there is probably an inconsistency between the fluid density predicted by the PVT model and the field data (rates/pressures). If PROSPER has to adjust Parameter 2 by more than +-10%, then probably the value of the roughness entered in the equipment is incorrect. In cases the PVT has been correctly matched, the greatest source of uncertainty in the VLP calculation for oil wells is usually the hold-up correlation. PROSPER will attempt to make a gravity component (Parameter 1) match by adjusting the hold-up correlation. If a match is not obtained with a Parameter 1 more than 5% away from 1.0, the density is adjusted. For single phase applications, no hold-up correction is possible, so any significant deviation from 1.0 for Parameter 1 indicates a PVT problem. If Parameter 2 requires a large correction, then it is likely that the equipment description is in error, or the flow rates are incorrect. As the effect of a shift in the friction component on the overall pressure loss is less than for the gravity term, a larger range in the value of Parameter 2 is expected. Once the matching process is complete, the match parameters will be shown alongside each of the correlations that have been matched. Use the standard deviations and the magnitude of corrections made to both parameters to aid the selection of matched correlation. Use the Correlation Comparison option of the Matching menu to compare the optimised (matched) correlations with measured test data. To ensure that the process has been successful, check that the matched VLP traverses plot close to the measured pressure PROSPER Manual
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data points. VLP matching provides a logically consistent means to adjust flow Ü PROSPER correlations to reproduce field measured pressures. Combined with IPR matching, PROSPER provides the means to create a robust well model that is capable of reproducing observed pressures and rates. This is a necessary condition for making accurate performance predictions and optimisation studies.
2.8.1.1.1 VLP Correlation Applications Fancher Brown is a no-slip hold-up correlation that is provided for use as a quality control. It gives the lowest possible value of VLP since it neglects gas/liquid slip it should always predict a pressure, which is less than the measured value. Even if it gives a good match to the measured down hole pressures, Fancher Brown should not be used for quantitative work. Measured data falling to the left of Fancher Brown on the correlation comparison plot indicates a problem with fluid density (i.e. PVT) or field pressure data. This is thus essentially, a correlation for quality control purposes. For oil wells, Hagedorn Brown performs well for slug flow at moderate to high production rates but well loading is poorly predicted. Hagedorn Brown should not be used for condensates and whenever mist flow is the main flow regime. Hagedorn Brown under predicts VLP at low rates and should not be used for predicting minimum stable rates. Duns and Ros Modified The Duns and Ros Modified correlation is derived from the Duns and Ros Original correlation. The original correlation was modified by Petroleum Experts to overestimate the pressure drop in oil wells for the slug flow regime. This correlation should only be used for quality checking of the input well test data. This correlation should not be used for calculating the pressure drop in the wellbore or pipelines and hence should not be used for lift curve generation either. Duns and Ros Original The Duns and Ros Original Correlation is derived from the original published method. In PROSPER the original Duns and Ros correlation has been enhanced and optimised for use with condensates. This correlation performs well in mist flow cases and may be used in high GOR oil wells and condensate wells. Petroleum Experts correlation combines the best features of existing correlations. It uses the Gould et al flow map and the Hagedorn Brown correlation in slug flow, and Duns and Ros for mist flow. In the transition regime, a combination of slug and mist results is used. Petroleum Experts 2 includes the features of the PE correlation plus original work on predicting low-rate VLPs and well stability. Petroleum Experts 3 includes the features of the PE2 correlation plus original work for © 1990-2011 Petroleum Experts Limited
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viscous, volatile and foamy oils. Petroleum Experts 4 is an advanced mechanistic model for any angled wells (including downhill flow) suitable for any fluid (including Retrograde Condensate). Petroleum Experts 5. The PE5 mechanistic correlation is an advancement on the PE4 mechanistic correlation. PE4 showed some instabilities (just like other mechanistic models) that limited its use accross the board. PE5 reduces the instabilities through a calculation that does not use flow regime maps as a starting point. PE5 is capable of modelling any fluid type over any well or pipe trajectory. This correlation accounts for fluid density changes for incline and decline trajectories. The stability of the well can also be verified with the use of PE5 when calculating the gradient traverse, allowing for liquid loading, slug frequency, etc. to be modelled. Orkiszewski correlation often gives a good match to measured data. However, its formulation includes a discontinuity in its calculation method. The discontinuity can cause instability during the pressure matching process; therefore we do not encourage its use. Beggs and Brill is primarily a pipeline correlation. It generally over-predicts pressure drops in vertical and deviated wells. Gray correlation gives good results in gas wells for condensate ratios up to around 50 bbl/MMscf and high produced water ratios. Gray contains its own internal PVT model which over-rides PROSPERs normal PVT calculations. Hydro 3P (internal) is a mechanistic model and considers three phase flow.
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For very high liquid dropout wells, use a Retrograde Condensate PVT and the Duns and Ros correlation.
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There is no universal rule for selecting the best flow correlation for a given application. It is recommended that the Correlation Comparison always be carried out. By inspecting the predicted flow regimes and pressure results, the User can select the correlation that best models the physical situation.
Further details can be found in the PROSPER Appendix B | Multiphase Flow Correlations.
2.8.1.2 IPR Matching This feature allows the User to check the consistency of the flowing bottom hole pressure data used in the VLP match and to adjust the IPR, if required, to match measured data. Inconsistencies in test data resulting from e.g. changing reservoir PROSPER Manual
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pressures can be easily identified. Clicking VLP/IPR from the VLP/IPR Matching screen will display the following VLP Matching – Adjust IPR screen:
Select the desired correlation and then click Calculate, and PROSPER will calculate the VLP for a range of rates and pressure at the sand face for each of the active test points that have been entered on the VLP Matching screen. Once this calculation is completed, click Plot and the VLP/IPR plot will be displayed along with the test point:
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The errors between calculated and measured data are shown on the side of the plot. If the test points are not consistent with the IPR model, the skin, etc. can be adjusted until a match is obtained. To modify the data of the IPR, select IPR, which will access the IPR input screen.
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NEW!!! During the adjustment of the IPR, to modify the value of the Reservoir Pressure, change the reservoir pressure entered in the test data screen
Inconsistent test data points will be easily identified on this plot. Clicking Finish returns to the Adjust IPR screen. Matching both the VLP and IPR to actual test data ensures that the PROSPER well model is capable of accurately reproducing the currently known producing conditions.
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An IPR is required when automatic rate calculation is used for VLP or system calculations. IPR data must be present before commencing a VLP/IPR Match.
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NEW!!! In the VLP Matching - Adjust IPR screen the option to allow/disallow Left-Hand Intersection is available. This option can be used in cases like Gas Coning
2.8.2 Gradient Matching This facility enables to modify the existing correlations to fit to a measured pressure gradient survey. It can also be used, as a quality control to identify which correlation required the least adjustment to obtain a fit. From the Matching menu, select Gradient (traverse) matching. The following screen will appear:
The first node pressure is entered in the Input Parameters section - do not include it in the Match Data table. The Transfer button copies the measured gradient data from the Correlation comparison data. The same guidelines for GOR apply as for VLP/IPR Matching. Enter the required data and click Match. The following will be displayed:
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Select the correlations to be matched by clicking on them, and then click Match to start the matching routine. Parameter 1 is the correction factor applied to the gravity component of pressure drop whilst Parameter 2 is the factor applied to the frictional element of pressure drop. The match algorithm continues until the standard error is less than 1 psi, or 50 iterations have been performed. The adjusted correlation and measured pressures can be visually compared by clicking Plot. A graph similar to the following is displayed:
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The match points appear as blue squares in the figure reported above. The calculated pressure gradient can be inspected by clicking View. Click the Statistics button to display the match parameters. Use the statistics and knowledge of well conditions and correlation performance to guide the choice of VLP correlation. Once a correlation has been matched, the match parameters are appended to the correlation name for all subsequent operations. Should it be necessary to adjust or clear the match parameters, click the Reset button for a particular correlation, or use the Reset All button to reset all correlations to their un-matched state.
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Best results are usually obtained by using VLP matching. VLP matching is the preferred option. Gradient matching is only to be considered for specialised artificial lift applications and where many (reliable) pressure Vs depth data points are available.
2.8.3 Surface Pipe Matching This option is used to match measured data with the calculated pressure drop from the wellhead to the manifold. This option is useful only if surface equipment has been entered in System Equipment. Select Surface pipe matching from the Matching menu to display the following input screen: © 1990-2011 Petroleum Experts Limited
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The User can now use the ‘Correlation Comparison’ button to transfer the selected pipeline test data to the pipeline correlation comparison section. The procedure is: · · ·
Click on the button to the left of the pipeline test data that we wish to perform correlation comparison on. Click on the ‘Correlation Comparison’ button PROSPER will bring us to the pipeline correlation comparison screen and at the same time, populate the correlation comparison screen with the selected pipeline test data.
Enter measured manifold and tubing head pressures for a range of rates and click M atch to enter the calculation screen. Select the correlations to match in the same manner as for Gradient matching. All editing and calculation controls operate as described under Gradient matching. Once the matching is complete, click OK to return to the main menu.
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If the system description has no elevation difference between the wellhead and manifold, there can be no gravitational component of the correlated pressure drop. Therefore, Parameter 1 cannot be optimised, so it remains at the default value of 1.0 for such cases.
2.8.4 Correlation Comparison This module allows a pressure gradient (traverse) to be calculated at a specified surface rate using any of the standard correlations. Actual measured pressures can be PROSPER Manual
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input and plotted on the same graph for comparison with the pressure calculated from the correlations. The correlations may be modified or unmodified (Matched or Unmatched). Click Matching / Correlation comparison to display the following data entry screen:
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Note that in Correlation comparison, the first node is the wellhead only if there is no surface equipment or it has been disabled.
Enter the surface flowing conditions at which to compare the flowing gradients calculations for the selected Vertical Lift correlations. Select a surface equipment correlation then click on the required Vertical Lift correlations to select a number of them from the list. Please remember that the lowest and highest pressure drops are © 1990-2011 Petroleum Experts Limited
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given by Fancher and Brown (no slip) and Duns and Ross Modified (highest pressure drop in the slug flow regime) for oil wells. These can serve as quality check boundaries for downhole measurements. Fancher Brown should never be used for actual calculations.
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Ensure that the rate type is correct for the specific application. The value of GOR should reflect the current solution GOR and at no time should exceed the initial solution GOR. The GOR Free variable is used to model the effect of free gas production from a gas cap or injection gas breakthrough. Leave GOR Free set to zero if there is no free gas production. The sum of GOR and GOR Free should equal the producing GOR.
Pressure data from a gradient survey can be entered versus depth in the measured data boxes. The Transfer button copies the measured depths and pressures from the G radient Match section.
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For gas lifted wells, both the injection depth and gas lift injection rate are required to be input. Note that the producing GOR should not include the lift gas injection.
When the input data is complete, click on Calculate to display the calculations screen, then press the Calculate button to compute the pressure gradient in tabular form as shown below:
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The results of individual correlations can be examined sequentially by clicking the arrows beside the Correlation field. For all the correlation selected for calculations, use the scroll thumb below the results box to access the results of calculations. PROSPER displays the following parameters as a function of depth:
· · · · · ·
Temperature, Pressure. Total Pressure Gradient, Static gradient, Friction Gradient. Flow regime, Liquid Hold up, Water Hold up, cumulative hold ups. Slip Liquid Velocity, Superficial Liquid Velocity, Slip Gas Velocity, Superficial Gas Velocity, Slip Water Velocity, Superficial Water Velocity. Mixture Density, Gas density, Oil density, Water density. Frictional Pressure Loss, Gravity Pressure Loss © 1990-2011 Petroleum Experts Limited
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· · · ·
Pipe Diameter, Angle of the tubing From Vertical, calculation Node Length Liquid Viscosity, Gas Viscosity, water viscosity, oil viscosity, Gas-Liquid IFT, Gas-Water IFT, Gas-Oil IFT, Oil-Water IFT C Factor and the max size of sand grain that can be transported Cumulative volumes of phases till that depth.
A visual comparison of all selected correlations and the test data is easily made by clicking on the Plot button. The plot can be output or saved using the standard features of PROSPER and Windows. An example comparison plot is shown below:
This plot is a useful quality check on the PVT and field production data. The Fancher Brown correlation does not allow for gas/liquid slippage, therefore it should always predict a pressure that is less than the measured value. Measured data falling to the left of Fancher Brown on the gradient comparison plot indicates a problem with fluid density (i.e. PVT) or the field data (pressure or rate). The use of the gradient comparison plot is recommended to help identify flow regimes and assess input data quality. Summary Plot From the Tubing Correlation Comparison it is possible to visualize a Summary plot
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This plot allows to compare the total dP and the components of the dp calculated by the various correlations, as well as the difference between the correlation pressure and the gauge pressure (Point i in the table):
Results
This consists of a table containing the summary of all the results for all the multiphase flow models
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Chart
Done
Select from the drop-down menu the component of the pressure drop to compare Return to the previous screen.
Export This option allows the user to export selected data to Printer, File, Clipboard or Screen. Help
View this Help screen
2.8.5 QuickLook for Gas Lift The QuickLook option is based on the principle of calculating well pressure traverses in opposite directions beginning from known conditions at the surface and sand face. If the assumptions regarding well conditions (e.g. gas injection rates and depth, water cuts, IPR etc.) are correct, the two calculated traverses would overlay. Troubleshooting a gas lifted well is performed by considering a range of assumptions, until a consistent calculation model can be obtained. By varying artificial lift and production parameters in turn, the experienced User can determine if the well is behaving as designed, or identify potential reasons to explain the deviation from design conditions.
2.8.5.1 Input The gas lift QuickLook is accessed from the Matching menu. Clicking QuickLook from the Matching menu displays the following screen:
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The surface measurements section contains two columns for data input.
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For analysing a particular well at a particular flowing condition, enter data in the Minimum column only. For unstable wells, enter the minimum and maximum conditions to be considered. The program will calculate using average values.
If unloading valve details have been entered, their opening and closing pressures will be shown on the plot also. The parameters required to be entered are: Tubing head pressure
Enter expected flowing pressure for the well.
Tubing head temperature
Used only for comparison purposes.
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Liquid rate
Enter current flow rate.
Water cut
Enter current value.
Total gas rate
Enter total gas production through the separator - including the lift gas contained in the produced well stream.
Gas injection rate
Enter current injection rate.
Casing head pressure
Enter current surface gas injection pressure.
Orifice diameter
Enter diameter of orifice where gas is entering the string. This diameter is used to estimate the pressure drop between casing and tubing at the injection depth. For wells having multiple injecting orifices at the same depth, enter an equivalent area.
Injection depth
Enter expected depth of injection.
Vertical flow correlation
Select the most appropriate correlation for the application. Use a matched correlation where available.
Dome Pressure Correction above 1200 psi
When set to Yes, the improved high-pressure dome pressure temperature method is used.
Thornhill-Craver DeRating
NEW!!! This coefficient is used to scale down the maximum gas injection rate that can be flowed through a valve or the orifice. As the maximum gas rate is decreased, this means that to flow the same gas rate as the original case (with no derating), larger valve or orifice should be used
To compare measured and calculated pressures to those calculated by the QuickLook, click Downhole, and enter the pressure survey data in the following screen:
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The purpose of this section is to check that all the data is consistent. The static gradient can also be displayed on the plot by entering two static pressure measurement points. Downhole measurement entry is optional.
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If a static pressure is entered on the downhole measurement screen, this will be used to calculate the sand face pressure from the IPR.
For PROSPER to determine which gas lift valves should be open and closed for the current producing conditions, the valve depths and characteristics must first be entered. Click Valves from the QuickLook screen to display the following:
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The valve type (casing or tubing sensitive), setting depth, port size, R-value and dome pressure at 60 °F are required to calculate whether valves are open or closed. Opening pressure etc. fields will be blank until a QuickLook calculation has been performed. Entering the valve data for the QuickLook is optional. As an alternative to entering them by hand, gas lift valve characteristics can be transferred from other sections of PROSPER. Click the Transfer button on the Valves data entry screen, and the User will be prompted to select the source of valve data. Select either From Gas lift valves, or From Gas lift design to pick up the depths that have been previously entered in Equipment Gaslift. After Transferring the valve depths, select the valve type for each depth. To manually investigate the effects of changing Rvalues and dome pressures, these values may be edited or entered by hand.
2.8.5.2 Performing the QuickLook Calculation Once the required (diagnostic) and optional (Downhole & Valves) data have been entered, click Calculate to display the calculation screen and Calculate again to begin the computation of the gradients. PROSPER begins by calculating from the top down, and then repeats the calculation from the sand face up. Select between the up pass and down pass using the buttons located beside the Case box as in the following example:
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In the Results box, the program displays the theoretical dP across the injecting valve together with the casing pressure theoretically required to balance the flowing tubing pressure at the injection depth plus the dP across the orifice.
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If the Valve Depths Specified option has been selected via the gas lift data section, then the gas gradient results will also become available to view via the above results screen
Click Plot to display the two computed gradients plus the valve opening and closing pressures on the same graph:
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This plot enables the User to see at a glance which valves should be open or closed, and how changes in operating pressures would impact on the valves. The results box displays the following computed values: Flowing BHP
From the IPR at the current flow rate.
Static BHP
Reservoir pressure input.
Tubing pressure at valve
Fluid side pressure at injection depth.
Casing pressure at valve
Gas side pressure at injection depth.
Temperature at valve
Interpolated for Predicting pressure only option. Can also be calculated using the Rough Approximation temperature option.
GOR
Calculated from production and injection rates and PVT.
GOR Free
Calculated from production and injection rates and PVT.
dP across valve
Pressure loss resulting from injection through the valve orifice.
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Theoretical casing pressure
Pressure at surface back calculated from the tubing pressure at injection depth plus the dP across the operating valve less the gas pressure traverse back to surface.
Producing draw down
Difference in static and flowing sand face pressures.
Equivalent P.I.
When flowing above bubble point, the production rate divided by the producing draw down.
Critical flow rate
Injection rate required for sonic velocity through the orifice.
% Critical flow rate
Actual injection rate as a fraction of the critical rate.
2.8.6 QuickLook for ESP The ESP QuickLook principle is identical to that for gas lift wells, i.e. pressure traverses are calculated from top to bottom and vice-versa. If the assumptions regarding well and ESP conditions (e.g. pump frequency, wear factor, water cuts, wellhead pressure, IPR etc.) are correct, the two calculated traverses will overlay. In addition, an energy balance is performed across the electrical system allowing surface voltage and power to be calculated and compared to measured data. Historically, ESP wells have been difficult to diagnose (particularly with limited down hole pressure data) because of uncertainties below (IPR), across (pump head) and above (tubing hydraulics) the pump. Using the ESP QuickLook, conditions in each of these areas can be analysed separately.
2.8.6.1 Input The ESP QuickLook is accessed from the Matching menu. Clicking QuickLook from the Matching menu displays the following screen:
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Select the required pump, motor and cable from the buttons at the top of the screen. Enter well test parameters as follows: Tubing head pressure Liquid rate Water Cut Produced GOR (solution GOR plus free gas) Static Bottom Hole Pressure (reservoir pressure) Enter measured data as follows: Current, surface voltage and Power PROSPER Manual
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Enter gauge data if available, usually pump intake and pump discharge pressures
Enter ESP related parameters as follows: Pump depth Depth of the pump Operating frequency
Frequency of operation of the pump
Length of cable
Used to calculate surface voltage. Normally the same as the pump depth, but could be much longer for sub sea ESP wells.
Gas separation efficiency
Enter the percentage of free gas at the pump intake that is separated and flows up the annulus.
Number of stages
Number of pump stages
Pump wear factor
Enter the fraction that represents degradation of pump head. Zero is no wear, one indicates no head will be developed. This can be used to model pumps stages that are worn due to sand or scale production or any other factor that downgrades pump performance.
Enter correlation
Select the most appropriate flow correlation for the application. Use a matched correlation where available
2.8.6.2 Performing the QuickLook Calculation Click Calculate to display the calculation screen and Calculate again to begin the computation of the pressure traverses. Ü
Note that PROSPER always calculates from the bottom up for ESP systems since, in order to find the tubing GOR above the pump, conditions at the pump intake where gas separation takes place must be known. The calculation of the downward pressure traverse from the entered tubing head pressure is therefore iterative.
Select between the up pass and down pass using the buttons located beside the Case box as in the following example:
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Click Plot to display the pressure traverses and the calculated pump intake and discharge pressures, down hole average rate across the pump (RB/day), free gas fraction at the pump intake and electrical parameters:
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If the well bore, inflow and ESP assumptions are all correct, the two pressure traverses will overlay and the measured and calculated intake and discharge pressures and surface voltages should coincide. The following guidelines may be useful in diagnosing ESP wells: Ü
The pump discharge pressure is the “tie” point for the system. First match the pump discharge pressure (if available) from the top down traverse. The pump discharge pressure depends only on the weight and frictional resistance to the flow rate through the tubing to surface. Next match the pump intake pressure from the top down traverse. If the calculated and measured pressure differential (head) across the pump is different, then the assumptions of pump wear, fluid density (water cut) and pump frequency should be examined. The top down traverse will now give the resulting bottom hole flowing pressure. This should be compared with the bottom up calculation and will indicate any discrepancy with the inflow performance module assumptions.
2.8.7 QuickLook for HSP The HSP QuickLook principle is identical to that for ESP wells, i.e. pressure traverses are calculated from top to bottom and vice-versa. If the assumptions regarding well and HSP conditions (e.g. pump and turbine speed, wear factor, water cuts, wellhead © 1990-2011 Petroleum Experts Limited
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pressure, IPR etc.) are correct, the two calculated traverses will overlay. 2.8.7.1 Input The HSP QuickLook is accessed from the Matching menu. Clicking QuickLook from the Matching menu displays the following screen:
Select the required pump and turbine from the buttons at the top of the screen. Enter well test parameters as follows: Tubing head pressure Liquid rate Water Cut Produced GOR (solution GOR plus free gas) Static Bottom Hole Pressure (reservoir pressure) Enter measured data as follows: PROSPER Manual
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Enter gauge data if available, usually pump intake and pump discharge pressures
Enter HSP related parameters as follows: Pump depth Depth of the pump Pump Speed Method
The pump speed can be either entered or calculated by the program (see below)
Pump Speed
Speed at which pump is operated
Power Fluid rate
This defines the power fluid rate injected to power the turbine
Power Fluid Surface Back Pressure
Minimum surface pressure of the injection circuit line
Number of Pump stages
Number of stages of the pump
Pump wear factor
Enter the fraction that represents degradation of pump head. Zero is no wear, one indicates no head will be developed.
Number of Turbine Stages
Number of stages of the turbine
Enter correlation
Select the most appropriate flow correlation for the specific application. Use a matched correlation where available
Equipment
Select the pump and the turbine from the PROSPER database
Pump Speed Method (NEW!!!) Two options of Pump Speed Method are available: Entered
The pump speed is entered by the user in the HSP input data and is used by the program to determine the power fluid rate that is able to satisfy the condition that the power consumed by the pump is equal to the power produced by the turbine. This method is the standard to calculate the gradient (or VLP curves for simulators like GAP) as in general the pump speed is known
Calculated This method calculates the speed required in order to operate the pump at the maximum overall efficiency for the value of the power fluid rate entered in the HSP input data section and suitable to satisfy the condition that the power consumed by the pump is equal to the power produced by the turbine
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In some cases there could be multiple solutions: PROSPER will determine the one with highest overall efficiency. This means that once the pump operating parameters (pump speed, power fluid rate, etc.) have been defined, both modes of calculation will be equivalent. 2.8.7.2 Performing the QuickLook Calculation Click Calculate to display the calculation screen and Calculate again to begin the computation of the pressure traverses. Note that PROSPER always calculates from the bottom up for HSP systems since, in order to find the tubing GOR above the pump, conditions at the pump intake where fluid mixing takes place must be known. The calculation of the downward pressure traverse from the entered tubing head pressure is therefore iterative. Select between the up pass and down pass using the buttons located beside the Case box as in the following example:
Click Plot to display the pressure traverses and the calculated pump intake and discharge pressures, down hole average rate across the pump (RB/day) and pump and turbine parameters:
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If the wellbore, inflow and pump and turbine assumptions are all correct, the two pressure traverses will overlay and the measured and calculated intake and discharge pressures should coincide. The following guidelines may be useful in diagnosing HSP wells: Ü
The pump discharge pressure is the “tie” point for the system. First match the pump discharge pressure (if available) from the top down traverse. The pump discharge pressure depends only on the weight and frictional resistance to the flow rate through the tubing to surface. Next match the pump intake pressure from the top down traverse. If the calculated and measured pressure differential (head) across the pump is different, then the assumptions of pump wear, fluid density (water cut) and pump speed should be examined. The top down traverse will now give the resulting bottom hole flowing pressure. This should be compared with the bottom up calculation and will indicate any discrepancy with the inflow performance module assumptions.
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2.8.8 Tubing Parameters This option allows the match parameters for the tubing pressure drop correlations to be accessed. They can be reset to their un-matched values, or new values entered directly.
2.8.9 Pipeline Parameters This option allows the match parameters for the surface piping pressure drop correlations to be accessed. They can be reset to their un-matched values, or new values entered directly.
2.8.10 Correlation Thresholds This option allows the User to specify alternative correlations to use for tubing or pipeline when the angle (from the vertical for tubing and from the horizontal for pipelines) exceeds a User-specified threshold value. This option is useful for modelling the riser for a long sub sea tieback or for a highly deviated surface pipeline. Enter the appropriate angles and correlations. Select Yes to the question Use Threshold Angle to enable the feature. When enabled, the calculation screens will indicate that this option is active.
2.9
Calculation Menu This chapter describes all the calculation methods available in PROSPER and how to calculate system production rates, run sensitivity analyses, generate lift curve tables etc. The available calculation types are: Inflow (IPR)
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This option calculates the IPR, that is to say, the relationship between tubing intake rate and the bottomhole flowing pressure (BHFP). The Inflow calculation allows to quickly run sensitivities without the need to calculate the system solution rate. This is especially convenient for e.g. frac program design, gravel pack design, perforation programming. System (Ipr+Vlp) This option will calculate both the tubing outflow (VLP) and tubing inflow (IPR) curves and determine the system operating rate and bottom hole flowing pressure. It also allows to perform sensitivity analyses with a wide range of variables. Sensitivity plots can easily be generated. Three options are available: - 3 variables (for naturally flowing wells) - 4 variables and - Multi-Variables ( up to 10 variables). Gradient (Traverse) This option enables the user to generate gradient plots. If the correlations have been matched, the gradients will be generated using the tuned correlations. VLP (Tubing curves) This option enables the generation of VLP curves that can be exported for use in various commercial reservoir simulators and Petroleum Experts' MBAL and GAP programs. Three options are available: - 3 variables (for naturally flowing wells) - 4 variables and - Multi-Variables ( up to 10 variables). Choke Performance This is a convenient choke calculator for flow rates, pressure drop or choke settings. Choke Performance Curves can be visualised. Generate for GAP Allows to automatically calculate well performance data for gas lifted or naturally flowing wells for use in Petroleum Experts’ GAP production system network modelling program. Not available when Enthalpy Balance is in use. Bottom Hole Pressure from Wellhead Pressure This option allows to calculate flowing bottom hole pressure from the wellhead pressure. This method is only available when using the Pressure and Temperature and Rough Approximation options.
2.9.1 Inflow (IPR) This calculation type enables the User to determine the IPR as the reservoir and fluid parameters change. © 1990-2011 Petroleum Experts Limited
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To select this calculation type, choose Calculation Inflow (IPR) from the main menu toolbar.
A few data on the fluid quality are required, along with the selection of the rate range for which to run the calculation. As far as the rate method is concerned, select one of the following: ·
Automatic Linear The program works out the AOF (IPR Absolute Open Flow) for various sensitivity variables entered and for each AOF creates 20 evenly spaced rates for sand face pressures calculations.
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Automatic Geometric As for Automatic Linear, it works out the AOF for various sensitivity variables entered and for each AOF creates 20 geometrically spaced rates for sand face pressures calculations.
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Use this option when evaluating minimum stable flow rates. ·
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User selected One can either enter a table of up to 20 rates directly, or use PROSPER to G enerate them. Click Generate from the User Selected rate entry screen and the following screen will be presented:
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Enter values for the first and last rates in the table plus the number of entries required. Depending on the selection of Linear or Geometric spacing, PROSPER will calculate the required rate table. Use the Try button for the preview of the entered range and Done to confirm. Ü
User selected rates can be useful when using the AOF is inappropriate for the range of sensitivity variables to be considered.
Click OK, then if a sensitivity analysis is to be performed, enter values for up to 3 sensitivity variables as on the following screen example:
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The range of Inflow variables available depend on the particular IPR model entered in S ystem Inflow performance. For each of the selected variables enter the values by hand, or click Generate to have PROSPER calculate a range of values as follows. The Generate feature is exactly the same as the one for the Rate Method entry. Leaving the sensitivity variable screen empty will run the calculation with the default parameters entered in the main IPR section. The Combinations button can be used to enter particular scenarios to calculate. Refer to Sensitivity Combinations in the section related to System Calculation for more details. Once set up the Inflow sensitivity variables, click OK Calculate to calculate the IPR pressures. The results will be reported in a table:
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In the Variables area scroll teh various parameter to display the desired sensitivity. The results can be exported to different destinations (like for example the Clipboard) by selecting Export. Clicking on Report will instead export the results to a Report sheet. Click Plot to display a screen similar to the following:
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On this plot by pressing on the VARIABLES option on the menu bar, one can get a display of all the variables that have been calculated during IPR calculations, like skin, dP skin etc. These can be plotted as well.
2.9.2 System (Ipr + Vlp) The Calculationú System (Ipr +Vlp) calculation type enables the User to determine the production of a well and the flowing parameters (like BHP, dP, etc.) as the reservoir and fluid parameters change, according the principles of nodal analysis. To enter the System Calculation area select CalculationïSystem (Ipr+Vlp) from the menu toolbar.
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The first input screen requires the Top Node Pressure and the data concerning the fluid quality (e.g. WC and GOR) and allows to select correlations for surface and downhole equipment as well as select a rate method. Ü
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The Top Node represents the downstream end of the system, hence it is: -
The manifold if surface equipment is included in the system
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The wellhead if no surface equipment is included in the system
The Solution Node represents the point at which the nodal analysis is performed. Three options are available: -
Bottom Node. It is the bottomhole, that is, the deepest point in the downhole equipment
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Top Node. See definition in the previous note
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Well Head. It is the Xmas Tree, that is, the upper point of the downhole equipment.
According to the last two definitions, if no surface equipment is included, Top Node and Well Head represent the same point. As far as the Rate Method is concerned, refer to the previous section for details. Ü
The Solution Rate reported is given by the VLP and IPR curves intersection. These curves are interpolated between the selected calculation rates and so the result may change according to the rate values used. It is important that an appropriate rates range and distribution is selected according to each case in order to avoid significant interpolation errors.
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An IPR is required for both Automatic rate methods. For wells having very high AOFs (e.g. horizontal wells) the well rate is determined mainly by the tubing size. Manual rate selection may give better results in such cases.
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For information on Wellhead Plot please see: Wellhead Plot
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For information on System Multi-Variable plotting options please see: System Multi-Variable Plotting
2.9.2.1 Left - Hand Intersection for VLP/IPR curves LHS: Left-Hand Side Normally VLP/IPR intersections that occur when the tubing pressures are declining (on the LHS) are considered to represent unstable flow and are usually ignored. When Gas Coning occurs, however the GOR is changing constantly for different rates and it is possible to have two solutions and for the LHS intersection to represent stable flow. This option allows to consider or not the left-hand intersection.
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2.9.2.2 Sensitivity Variables Screen Once entered the main input data, select Continue to access the sensitivity variables screen. This is organized exactly in the same way as in the Inflow calculation, hence refer to Section 10.1.1 for details on the use of this entry screen. Ü
Three types of System calculation are available: · 3 variables · 4 variables and · Multi-Variables
Only the sensitivity variables relevant to the chosen system will be available. For example, if a well is gas lifted th euser will be given the option of gas injection rate as a variable. This option will not be available if the well is naturally flowing.
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When tubing diameter is entered as a sensitivity variable, selecting Continue displays a screen where the User can input the range of nodes over which the sensitivity is calculated:
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Normally tubing diameter should not be varied in the casing below the tubing shoe. This option is also useful for determining e.g. the effect of increasing tubing size above a safety valve while keeping the diameter of the rest of the tubing string diameter constant.
2.9.2.2.1 Sensitivity Combinations Screen The Combinations option allows the User to enter specific combinations of field data (or hypothetical cases) then allow the program to calculate the unknowns. An example of a Combinations screen is shown below:
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If no liquid rates are entered, the program uses the current list of rates (either internally calculated or User input) and calculates the solution for the combination of sensitivity variables for each of up to 10 cases. If liquid rates are entered in the Combinations screen, these take precedence. The program will then find the VLP and IPR pressures for each combination of sensitivity variables. Note that a solution rate is not computed in this case.
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Once sensitivity values have been entered in either the Combinations or Variables screen, click Continue to display the calculation screen. Sensitivity values temporarily overwrite variable values that have been entered on other screens. For example: Pressure at first node, water cut.
2.9.2.3 Calculation Screen Click Calculate to start the system solution calculations. A calculation screen example is shown below:
On the right hand side there are the results of the system calculation: solution rates, FBHP, WHP, WHT, etc. On the left hand side, instead, there are the calculated parameters related to VLP and IPR. Scroll to the right to read the results. In the Variables area it is possible to scroll the different cases or the values of the sensitivity variables for which the calculations were performed. Solution Details To examine the solution in more detail, click the Solution Details button. Individual solution points can be viewed by clicking on the arrow buttons located beside each PROSPER Manual
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sensitivity variable. Outflow or Inflow solutions can be viewed as shown in the following sample screen:
In the case of wells with ESP, HSP, PCP or Jet Pump, the solution details contain all the results related to the pump. Plotting Results The results can be plotted by clicking Plot. The System plot will appear as follows:
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The system plot summarizes all the calculations. Each VLP and IPR curve is identified by up to 3 numbers posted beside them. The variable names and the corresponding number labels are shown in the panel to the right of the plot. In the above example, Curve 1,0,0 is for 4500 psig reservoir pressure, 0 % water cut and 4 STB/day/psi productivity index. To plot the solution rates and pressures versus the selected variables, click Sensitivity and a sensitivity plot will be displayed. To select sensitivity variables to plot, click V ariables and make the selection on the following screen, for example:
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The Sensitivity screen allows to choose X- and Y-axis variables. Click OK to view the Sensitivity plot. The program automatically plots the sensitivity values of the X-axis variable. If variable Combinations have been used, the sensitivity cases will be automatically plotted.
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The pressure gradient for any particular solution rate can be calculated by clicking Se nsitivity PvD (Sensitivity Pressure vs. Depth). Performing Gradient Calculations for a Given Solution For each of the solutions calculated it is possible to determine the correspondent gradient. To do so, in the System Calculation screen select Sensitivity – PvD:
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Select the desired case by scrolling on the variables, and then Continue and Calculate to generate the gradient. The results are displayed on the following screen example:
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Click Plot to display the Gradient vs. TVD or Measured Depth:
Click Variables on the plot screen to select which variables to plot.
By clicking the Extended button, a greater range of plot variables can be accessed. Virtually any combination of computed results can be plotted against each other.
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Return to the standard choice of plot variables by clicking the Original button. The plots are held in memory until overwritten by a new set of calculations. Plots can also be displayed or output by selecting Plot from the main menu. The Units menu can be used to change the display units if required. Special Note for ESP, HSP, PCP and Jet Pump Applications When calculating a System solution for a pump equipped well, in the Solution Point screen lists details of the pump solution such as pump intake pressure etc. (See example pump solution in the screen below)
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Clicking Pump Plot on the pump solution screen displays the sensitivity solutions plotted over the pump characteristic curves (this is available only for ESP and HSP). As shown by the example screen below, the effects of the sensitivity variables on the pump operating point can be readily evaluated.
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This plot is a powerful tool for evaluating how an ESP design can accommodate future changes of well conditions. Ü
All pump (both ESP & HSP) designs should be validated by calculating sensitivities and ensuring that efficient operation at the design rate can be achieved over the entire range of expected well and pump efficiency conditions.
For pump (both ESP & HSP) equipped wells, the Sens. PvD gradient calculation shows the pressure increase across the pump. An example gradient plot is shown below:
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2.9.3 Gradient (Traverse) The Calculationú Gradient (traverse) feature allows the User to calculate flowing pressure gradient curves at a specified flow rate for varying reservoir and fluid conditions. These curves can be compared with published pressure traverse curves or actual well data. Pressure traverses can also computed for combinations of sensitivity variables. The effect of changing tubing sizes, SSSV I.D. etc. can be evaluated visually by plotting the gradient results. To commence the Gradient calculation, click Calculation Gradient (traverse) from the main menu and the following screen will be displayed:
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Enter the required data, mostly the same as the one requested by System calculation, plus the first and the last node for the calculation, which will determine the section of completion for which to run the gradient calculation. Then select Continue to access the Sensitivity Variables (or Combinations) screen. Refer to previous sections for the description of this area. Selecting Continue again will access the calculation screen. In this screen the User can select the flow correlations for the downhole and the slug method:
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Click Calculate to compute flowing gradients for all the sensitivity cases. Once the calculations have been completed, the results tables can be inspected by clicking the respective variable arrows until the desired variable combination is visible. Ü
Important The Gradient calculation results report very useful parameters concerning details on the DP calculation, PVT data, mass flow rates and in the case of pipeline gradients, characteristic parameters of slugs, etc.
A plot of the gradient results similar to that below can be displayed by then clicking the Plot button:
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Gradients can be plotted for the well and flow line separately or combined on the one plot.
2.9.3.1 Options Every time a Gradient calculation is performed, a number of post-process calculations are carried out, like for example maximum grain size, erosional velocity, liquid loading (Turner velocity) and pigging calculations. The parameters affecting these calculations can be accessed in any Calculation screen by means of Options button. This screen can also be accessed from the main menu toolbar by selecting Systemï Solids.
2.9.3.1.1 Maximum Grain Diameter This calculation determines the maximum size of sand grain that can be dragged away by the producing fluid. The calculated Maximum Grain Diameter is reported in the results table at each calculation step. This calculation determines the maximum size of sand grain that can be dragged away by the producing fluid. The calculated Maximum Grain Diameter is reported in the results table at each calculation step.
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The model implemented in PROSPER is based upon a series of equations derived by Thomas (Reference 3) to calculate the friction velocity at the limit of solid transport in a liquid / solid system. Sand will be lifted to the wellhead only if the velocity of the fluid in the wellbore is greater than the “Critical Transport Velocity”. This velocity is function of sand particle size, shape and density and the fluid density and viscosity. Two different equations are used: one for oil wells and one for gas well: 1. Oil Wells The equation used in this case is more applicable to laminar flow, conditions that are likely to be encountered in oil and / or water wells.
Where: -
V = Critical Transport Velocity (cm/sec) equivalent to Superficial Fluid Velocities in PROSPER
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N = Dynamic Fluid Viscosity (poise) equivalent to Mixture Viscosity in PROSPER
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g = Gravity (980 cm/sec2)
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r = Particle Radius (cm) This is the parameter calculated by PROSPER
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= Fluid Density (gm/cm3) By default, PROSPER uses a 2.65g/cc sand density. This can be changed in the System | Solids section of the main PROSPER menu.
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= Particle Density (gm/cm3)
2. Gas Wells The equation used in this case is applicable to high gas flows and does not include a factor for viscosity: viscosity has only an insignificant effect on lifting sand.
Where: -
V = Critical Transport Velocity (ft/sec) Equivalent to Superficial Fluid Velocities in PROSPER
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= Fluid Density (lb/ft3)
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= Particle Density (lb/ft3) By default, PROSPER uses a 2.65g/cc sand density. This can be changed in the System | Solids section of the main PROSPER menu.
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g = Gravity (32.2 ft/sec2)
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d = Particle diameter (ft) This is the parameter calculated by PROSPER
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Cd = Drag coefficient for the particle – essentially a function of particle shape at high Reynolds numbers. Cd value for sand grain is 0.85.
In both the oil/water and gas cases, PROSPER knows the fluid velocity in the wellbore. Therefore, it will calculate the maximum particle diameter that can be transported by the well flow. These calculations are important when an attempt is made to cut back the production rate so that the well will stop producing sand and will help determine if the formation
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sand may be accumulating at the bottom of the well.
References: 1. Fairhurst.CP – “Sand Transport in the South East Forties Pipe Line”, BHRA, 1983 2. Smith.M – “A Model for Predicting Solids Transport in near Horizontal MultiPhase Oil and Gas Pipe Lines”, XFE report 8/2/1993 3. Wasp, Kenny & Gandhi – “Solid-Liquid Flow Slurry Pipe Line Transportation”, Gulf Publishing Company, Clausthal, Germany 1979
2.9.3.1.2 Erosional Velocity Calculation for Sand Laden Fluids When gradient traverse calculations are performed the program will estimate the correspondent value of erosional velocity. Erosion can be caused by the repeated impact of solid particles on tubing and pipelines. To avoid this we attempt to estimate the velocity at which erosion will occur. Normal practise is to use equation of API 14 E. This can be unreliable especially for clean production where the limiting value of C (125) can be too restrictive. In practice, values of 1000 for C have been recorded in pipes where no erosion has been detected.
A Conoco paper (An Alternative to API14E Erosional Velocity Limits for Sand Laden Fluids) challenges API14E on the basis that it can be very conservative for clean service and is not applicable for conditions where corrosion or sand are present. It proposes a simple alternative approach that has been verified by a comparison with several multiphase flow loop tests that cover a broad range of liquid-gas ratios and sand concentrations. Values of S for different components are proposed in the paper PROSPER Manual
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The constants C and S for the two formulations can be customised by selecting System ïSolids and tab button Erosional Velocity or the Options button in any calculation screen. PROSPER calculates the erosional velocity for solid-free fluid using the API-14E method and the entered “C” value. If the sand production rate has been specified, PROSPER will calculate the erosional velocity using both the API-14E and Conoco methods and will then compare the results and will use the computed lower-value of erosional velocity. To review the computed erosional velocity values using the Conoco method set the value of “C” sufficiently high until the values do not change for changing values of “C”. After gradient calculations are performed, scroll right on the results screen to view the erosional velocity values.
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In PROSPER, the C value is calculated and displayed and it is the responsibility of the User to work out whether for this C value, erosion will occur or not depending upon the expected operating conditions.
2.9.3.1.3 Gradient (Traverse)-Modified Turner Equation The Turner Equation is used to study the continuous removal of liquid from gas wells. This equation is used to determine the minimum velocity of the producing fluid necessary to drag away the droplets of liquid. The original formulation of the equation is the following:
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This formulation has been found to be not necessarily reliable. The original Turner Constant was 20.4. Using the Petroleum Experts 4 mechanistic model it has been found that 2.04 gives much more reliable results in a wide range of examples. This constant can be however changed by the User by selecting SystemïSolids from the main menu, or the Options button and the Liquid Loading tab screen within any calculation screen.
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results table, as reported in the figure above.
2.9.3.1.4 Pigging This calculation can be used to describe the pigging characteristics of the flow in pipelines. Assuming 100% removal efficiency of a sphere and that all the liquid removed by the sphere is in the form of a continuous slug, the pigged slug volume can be estimated by integrating the difference between the liquid hold-up and the no-slip hold-up in the pipeline. Also the time to produce the slug can be calculated from
These are the additional results reported in the Gradient Traverse results table: • Pigged Slug Length • Pigged Slug Volume (cumulative pigged slug volume for the given pipe element node) • Time to Produce Pigged Slug Length • Time for Pigged Slug to reach Outlet Pigging Efficiency can be entered by User.
2.9.3.2 Note on HSP Two options of Pump Speed Method are available: Entered
The pump speed is entered by the user in the HSP input data and is used by the program to determine the power fluid rate that is able to satisfy the condition that the power consumed by the pump is equal to the power produced by the turbine. This method is the standard to calculate the gradient (or VLP curves for simulators like GAP) as in general the pump speed is known
Calculated This method calculates the speed required in order to operate the pump at the maximum overall efficiency for the value of the power fluid rate entered in the HSP input data section and suitable to satisfy the condition that the power consumed by the pump is equal to the power produced by the turbine
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In some cases there could be multiple solutions: PROSPER will determine the one with highest overall efficiency. This means that once the pump operating parameters (pump speed, power fluid rate, etc.) have been defined, both modes of calculation will be equivalent.
2.9.4 VLP (Tubing Curves) An important PROSPER application is generating tubing lift curves for use in reservoir and total system simulators. Three options of calculation are available: · VLP curves – 3 Variables. The lift curves can be generated for a set of 3 sensitivity variables. The option is used for naturally flowing wells. · VLP curves – 4 Variables The lift curves can be generated for a set of 4 sensitivity variables. The option is used for artificially lifted wells. · VLP curves – Multi-Variables The lift curves can be generated for a set of up to 10 sensitivity variables. The option is mainly used to generate lift curves for gas lifted wells with an extra sensitivity on casing pressure (suitable to model and optimise in GAP gas lift injection networks)
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For information on VLP curves Multi-Variables plotting options please see: System Multi-Variable Plotting
2.9.4.1 VLP (Tubing) Curves - 3 Variables To generate lift curves for naturally flowing wells select Calculation VLP (tubing curves) 3 Variables from the menu toolbar. The input screen entry are similar to the ones required by System calculation (refer to the correspondent section for reference). The values of Top Node Pressure, Water Cut and GOR entered in this screen will be neglected if these variables will be selected as sensitivity parameters.
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When User Selected rates are used, the user can enter rates in terms of Liquid, Oil or Gas. The results will be given in terms of the specified rate type, but depending on the type of well, PROSPER will first convert the rates to equivalent oil or gas to calculate the VLP pressure. This feature can be used when preparing lift curves for high GOR oil wells. Remember when using gas rates, that increasing the water cut will also increase the liquid production rate. Extreme VLP pressures can easily result. Gauge Data: The information on the Gauge Data is used for Integrated Field Management (IFM) Applications. These can be left blank for use in IPM suite of tools. Click Continue to access the Select Variables screen and set up the required sensitivity variables. To generate lift curves for simulator (like Eclipse) for an oil well, the VLP is generally calculated for the following sensitivity variables: · Variable 1: Pressure at first node · Variable 2: Water cut PROSPER Manual
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· Variable 3: Gas Oil Ratio An example calculation variables screen for generating lift curves is shown below:
Select the variables required by the external application and enter a list of values for each. Click Continue to access the calculation screen, then select Calculate to generate the lift curves. An example lift curve calculation screen is shown below:
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The calculated VLP results can now be exported to a number of external application programs. Once the calculations have been completed, click Plot to visually check the results and Export Lift Curves to access the export selection screen. Currently, PROSPER supports the following export formats:
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Schlumberger - ECLIPSE Welldrill - SIMCO 3 ExxonMobil - Pegasus SSI – COMP4 FranLab – FRAGOR SSI – COMP3 LandMark - VIP Roxar - MORE Petroleum Experts – GAP/MBAL Shell - MoReS BeCip - ATHOS Amoco - GCOMP Chevron-CHEARS ExxonMobil-EMPOWER ConocoPhillips-PSim CMG-IMEX/GEM
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.ECL .SIM .MOB .CP4 .FRA .CP4 .VIP .MOR .TPD .MRS .ATH .GCM .CHE .Hyd .WBH .IMX
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PROSPER appends the export file with a suffix corresponding to the selected file format as shown in the table above. Depending on the export format selected, the User will be prompted for a file name and additional data such as table number, flow table I.D. etc. Refer to the simulator documentation for further details. Ü
Simulators have varying requirements for VLP sensitivity variables. If the correct variables have not been selected for calculation, PROSPER may not be able to correctly export the VLP file. Pay particular attention to GLR and GORs. To model artificially lifted wells, reservoir simulators require 4 variable lift curves. Refer to the following section for details.
2.9.4.2 VLP (Tubing) Curves - 4 Variables To model artificially lifted wells, an additional sensitivity variable is required. This option allows calculation of four variable sensitivities (provided the total number of sensitivity combinations is less than 10,000) and export of lift curves for gas lifted and ESP, HSP, etc. equipped wells. Set up, calculation and export of 4 variable tubing curves follows the same procedures as described above (Section 10.1.6.1) for regular tubing curves. An example of a 4 variable VLP calculation for a gas lifted well is shown on the following screen:
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A Note on Preparing Lift Curves Because of the large number of calculations that must be performed, preparing lift curves can be a time consuming process, so it is important to obtain good results at the first attempt. Due to the extreme range of flowing conditions that must be covered by the lift curve tables, problems with the computations are occasionally encountered. The following discussion covers some of the points that should be addressed when planning a lift curve calculation run. ·
Finding a VLP correlation that performs well for the entire range of rates that must be spanned by the lift curves can be difficult. Some correlations handle slug flow (e. g. Hagedorn Brown) but fail in the mist flow regime e.g. after injection gas breakthrough. Care must be exercised in selecting correlations to ensure that the
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wells are properly represented over the most important range of flow rates to be modelled in the simulation. ·
Problems can occur for extremes of water cut and GOR. e.g. if the oil production rate is fixed, the liquid production rate becomes very high as the water cut approaches 100%. To maintain lift in a high water cut well, a specific GLR is required. If injection gas is expressed in terms of GOR injected, the required GOR approaches infinity as the water cut approaches 100%. A huge range of GOR injected is therefore required to model the well. The use of liquid rates and injection GLRs in oil well lift curve tables is recommended to avoid such problems.
·
Depending on the particular simulator used, it is not possible to pass the variable names or units between programs. Users are reminded to ensure that the sensitivity variables and output units used in PROSPER are consistent with those expected by the simulator. In particular, gas units (MMscf Vs Mscf), gas lift (GLR Vs Gas Lift Injection Rate) and rates (Oil Vs Liquid) should be checked.
·
PVT correlations should only be used within the range of temperature and pressure for which they were derived. Occasionally, combinations of tubing curve variables require an excessive VLP pressure to pass the specified rate, and the PVT correlation may fail. Occasionally, PROSPER may halt rather than continuing the calculation with a fictitious result. The user may have to revise the range of variables or select a different PVT correlation in such cases. Beware of chokes and restrictions in the equipment description that may result in excessive calculated pressure drops. If using externally generated PVT tables, they must span the entire calculation range. Make sure that GOR is constant above bubble point, and the FVF is decreasing.
·
Provided the user enters the rates by hand, it is not necessary to enter an IPR to calculate VLP tables. PROSPER needs the IPR to find the calculation rates if an Automatic rate method has been selected. Automatic rate selection is not available for 4 Variable VLP calculations.
·
Oil well lift curves can now be calculated in terms of gas rates for specialised applications. Make sure that the liquid rates that result from the choice of GOR, water cut etc. does not result in impossible liquid rates. Be especially careful when there are chokes and restrictions in the system.
A Note on preparing lift curves for ESP equipped wells There are 2 options available for generating ESP lift curves: · ·
Tubing Curves (standard) Lift curves for simulators
The 'Tubing Curves (Standard)' option will prompt the user to enter the bottom hole pressure, i.e. the first node pressure corresponds to the bottom hole pressure. PROSPER will perform the calculations from the deepest node (i.e. bottom hole) to the PROSPER Manual
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pump depth. Using the pump performance curves, Pump Head is calculated for the given frequency, water cut etc. and therefore the Pump Discharge Pressure can be calculated. PROSPER then determines the PVT of the oil above the pump after accounting for possible gas separation. The pressure drop above the pump is then calculated to find the top node arrival pressure. These calculations are performed for each required production rate. The VLP Pressure value indicated corresponds to the Pressure at the end point of the system; i.e. if there is no surface equipments entered, the VLP Pressure will correspond to the wellhead pressure, if surface equipment is entered, then VLP Pressure will correspond to the Manifold Pressure. 'Lift Curves for Simulators' require tables of rates and BHPs ordered by THP. The Lift curves for Simulators option allows input of Top Node pressure, water cut, operating frequency etc. PROSPER iterates to find the pressure at the deepest node (VLP) for the given top node pressure. For this case the Top Node Pressure will correspond to the Wellhead Pressure (if there are no surface equipments entered) or the Manifold Pressure (If there are surface equipments entered). The VLP Pressure will correspond to the Bottom Hole Pressure or the pressure at the last point in the downhole equipment section.
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VLP lift curves for simulators or Petroleum Experts’ applications (GAP and MBAL) can be batch generated for groups of wells by PROSPER from GAP. Refer to the GAP documentation for details.
A Note on preparing lift curves for HSP equipped wells (NEW!!!) Two options of Pump Speed Method are available: Entered
The pump speed is entered by the user in the HSP input data and is used by the program to determine the power fluid rate that is able to satisfy the condition that the power consumed by the pump is equal to the power produced by the turbine. This method is the standard to calculate the gradient (or VLP curves for simulators like GAP) as in general the pump speed is known
Calculated This method calculates the speed required in order to operate the pump at the maximum overall efficiency for the value of the power fluid rate entered in the HSP input data section and suitable to satisfy the condition that the power consumed by the pump is equal to the power produced by the turbine In some cases there could be multiple solutions: PROSPER will determine the one with highest overall efficiency. © 1990-2011 Petroleum Experts Limited
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This means that once the pump operating parameters (pump speed, power fluid rate, etc.) have been defined, both modes of calculation will be equivalent.
2.9.4.3 VLP (Tubing) - Multi Variables PROSPER can generate lift curves for up to 10 variables as shown below:
The VLP Multi Variable should be used when modeling and optimising simultaneously gas lifted oil field and gas lift distribution network both in GAP. This is achieved by generating the VLPs with an extra sensitivity variable, casing pressure.
2.9.5 Choke Performance This is a general purpose choke performance calculator. Only PVT data input is required to calculate flow rates given the choke size and pressures, choke setting to achieve a specified flow rate etc. To access the choke performance calculator, click C alculationú Choke Performance and the following selection screen may be displayed (depending on the Choke Method selected): PROSPER Manual
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Calculation Options Select the required calculation option from the following: · Predict Mass Flow Rate PROSPER determines the flow rate for specified choke opening and inlet and outlet pressures
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· Predict Pressure Drop PROSPER calculates the pressure drop across a specified choke opening for a given flow rate and inlet pressure · Predict Choke Valve Setting PROSPER finds the choke size for a specified rate and inlet an outlet pressures. Choke Method Select a choke calculation method from the following options: · Petroleum Experts This is an in-house developed choke model based on Perkin’s work (SPE 20633). · HYDRO There are 3 distinct methods for modelling specific choke equipment. Until performance testing is completed and documentation issued, these choke methods should not be used. ·
ELF A model based on Perkin’s (SPE 20633) approach along with discharge coefficients determined by the author (Stephane Rastoin of ELF Aquitaine at TUALP). This is also the recommended method used to calculate pressure drops down hole for SSSVs and restrictions. It should be used for the majority of applications.
Enter the following data: · · · · · · ·
GOR Water Cut Inlet Pressure Inlet Temperature Outlet Pressure Outlet Temperature Choke setting
This value overrides the GOR entered on the PVT data screen. Pressure upstream of the choke Upstream temperature Downstream pressure Downstream temperature Orifice size
Click Calculate, and PROSPER will calculate the liquid and mass flow rates. Similar screens are used to enter data for the dP and Choke Setting prediction options. For critical flow conditions, it may take some time for the calculation to converge. Ü
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If the ELF Choke model is selected, after a calculation the Choke Performance Curve is plotted at the bottom of the screen
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Selecting the choke model in PROSPER To select the choke model to be used to model chokes, SSSVs and Restrictions, access the Surface Equipment screen and select from the dropdown menu Choke Method the desired model
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When one of the enthalpy balance temperature models (Improved Approximation or Enthalpy Balance) is selected, the choke calculation will account for changes of temperature due to Joule-Thomson effect
2.9.6 Generate for GAP This option is used to calculate well performance curves for Petroleum Experts General Allocation Program (GAP). PROSPER can be run from within GAP in a batch mode for generating performance curves for groups of wells or independently of GAP by selecting this option. PROSPER will automatically calculate solutions for gas lifted or naturally flowing wells. If the solutions are then saved in a .OUT file, GAP can pick up the data required to calculate performance curves at a later time. For more information, refer to the GAP documentation.
2.9.7 Bottom Hole Pressure from Wellhead Pressure SUMMARY The Well Head Pressure (WHP) to Bottom Hole Pressure (BHP) module has been programmed to work for oil, gas and retrograde condensate production wells. In order to activate the module PROSPER must be set up to calculate Pressure and Temperature using the Rough Approximation Method. This is configured in PROSPER under the main Options menu. Segregation of liquid and gas. For the flowing conditions the bottom hole pressures are calculated using standard multi-phase flow correlation’s. PROSPER calculates the retrograde liquid drop out in the tubing during production. This method can give significantly different pressure drops compared to assuming an equivalent dry gas corrected for its condensate content. For shut-in conditions the model assumes instantaneous segregation of gas and liquid. At the time of shut in the model uses PROSPER’s PVT module to determine the amount of free gas and condensate in the wellbore. The calculation starts with the wellhead pressure and calculates a gas pressure gradient downwards until all free gas volume is © 1990-2011 Petroleum Experts Limited
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used up. Thereafter a condensate pressure gradient is used down to the bottom of the well. If free water is produced then a water pressure gradient will be used below the condensate gradient to the bottom of the well. Temperature prediction using superposition effects The pressure gradient in the well bore is dependent on the temperature gradient. The temperature gradient is calculated using a method presented in SPE paper 22870 "Modelling of Well bore Heat Losses in Directional Wells under Changing Injection Conditions". When a well is shut in, its’ fluid temperature gradient changes with time as the well cools down towards the geothermal gradient. The rate of cooling is a function of its rate of heat loss to the formation and the rate of cooling of the formation around the wellbore. PROSPER uses a superposition method to estimated the temperature profile in the well after it is shut in. To calibrate the model effectively at least three flowing wellhead data points should be entered prior to shut in. For shut in cases set the WGR to zero, do not use a WGR to represent the solution water in the gas. Reliability of Results The current method used in PROSPER predicts the highest bottom hole pressures based upon conditions in the well. In the field the reservoir characteristics will also effect the bottom hole pressures. Condensate, may for example, drain back into the reservoir and be replaced by gas due to gravity segregation. In this case the bottom hole pressure predicted by PROSPER would be too high. Activating the WHP to BHP module To activate the WHP to BHP calculation module in PROSPER the Pressure and Temperature using the Rough Approximation Method must be selected. This is configured in PROSPER under the main Options Menu. The input data required is PVT specific, including wellhead temperature and pressure. The input screen will automatically change based on the PVT model that has been selected via the Options Menu In the case of gas lifted wells, the gas lift gas rate is also a required input. For ESP lifted wells, the pump frequency is a required input.
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When a surface flow line description is included in the system, the First Node option (circled above) must be set to Manifold. The manifold pressure and wellhead temperature will be required inputs
The table is quite large allowing to start off with up to 16000 rows of data which is automatically expandable up to 32000 rows. The data can be scrolled with the scrollbar at the right hand side of the screen. Appropriate vertical lift and surface pipe correlations can be selected at the bottom of the screen. Selecting the import button allows to bring in data from an outside source. Table data can be saved to file using the export button and plots using either time or the log of time can also be viewed and exported using the plot feature. Within the plot screen data can be enabled or disabled point by point or in a block manner by using the right-click mouse button.
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Data can be ordered with relation to time by using the sort button. This will also remove any blank rows between data in the table.
2.9.7.1 References SPE PAPER 22870 Modelling of Well bore Heat Losses in Directional Wells Under Changing Injection Conditions K Chu and S Thakur, Amoco Production Co.
2.9.8 Note on Enthalpy Balance Model The Predicting Pressure and Temperature analysis option can be used to generate temperature and pressure profiles in producing wells. This rigorous thermodynamic model Enthalpy Balance considers heat transfer by conduction, radiation, forced and free convection. Heat transfer coefficients are calculated using thermodynamic data held in a User-definable database. The temperature prediction calculations are transient, allowing sensitivities against flowing time to be run for both wells and pipelines. This temperature model requires considerably more input data and computation time for either Predicting Pressure Only or the Rough or Improved Approximation temperature models. Enthalpy Balance should be applied only when the desired result is the temperature. The additional computational effort cannot be justified for pressure loss calculations. PROSPER Manual
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Both pressure and temperature losses across chokes and restrictions are accounted for. A theoretical outline of the Enthalpy Balance model is given in Appendix B. Temperature prediction is useful for generating temperature profiles in: pipelines sub sea wells high pressure/temperature exploration wells predicting temperature/pressure profiles to help predict wax/hydrate deposits. · accounting for Joule-Thompson effects · · · ·
PROSPER 's Enthalpy Balance temperature model is one of the most accurate temperature prediction methods available. Ü
The Enthalpy Balance (or Improved Approximation) temperature calculations must commence from a known condition. This is usually the reservoir pressure and temperature. As a consequence, calculating from a downstream node (unknown temperature) to an upstream node (known temperature) is not meaningful. For injectors, calculations commence from the known wellhead pressure and temperature.
2.9.9 Reset Results NEW!!! In the calculation menu the Reset Results has the objective to erase any results previously calculated in the model.
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After accessing this option, select the calculation to reset and then select Reset: the program will erase the desired results.
2.10 Design Menu The Design Menu enables the User to perform various artificial lift designs. From this menu the User can access the design modules for the following artificial lift technologies: PROSPER Manual
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Gas Lift (continuous) Electrical Submersible Pump Hydraulic Drive Downhole Pump Progressive Cavity Pump Coiled Tubing GasLift Jet Pump Sucker Rod Pump Gas lift (intermittent) The design menu is active only if an artificial lift method has been selected in the main Options screen. The design option will correspond to the artificial lift method selection in the main Option screen. Artificial lift design is not enabled when the Enthalpy Balance temperature model is in use.
From the Design menu the Database containing all the information about gas lift valves, ESP pumps, motors, cables, etc. is accessible. A dedicated section is reported at the end of the chapter. In the following sections each of the design options are illustrated.
2.10.1 Continuous Gas Lift Design The gas lift design can be used to design and optimise the design of gas lifted wells. The program will determine the spacing and size of unloading valves and calculate the valve test rack setting pressures. Designs can also be performed for existing wells having mandrels installed at fixed depths. Design performance can be evaluated using the Gas Lift QuickLook or calculating system sensitivities. 2.10.1.1Menu Options If gas lift was selected as a lift method in the Options menu the following additional options will be available in the DesignïGaslift menu: · New Well · Existing Mandrels · Gas Lift Adjustments The gas lift design section of the program can be used to determine the optimum gas lift © 1990-2011 Petroleum Experts Limited
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equipment for a given well. PROSPER calculates the maximum production rate possible, the corresponding optimum gas lift rate, the valve spacing and size to unload the well and the test rack setting pressure for each valve for surface calibration. Designs can also be prepared for wells having mandrels already set at fixed depths. Before the User can proceed ahead with artificial lift design, PVT, downhole equipment and IPR information must be input.
2.10.1.2New Well Selecting Designú Gas Liftú New well from the Design menu will display the Gas Lift Design input screen:
In this screen it is possible to enter the input data for the gas lift design task. The input data screen is divided into several areas. The Input parameters panel is used to enter the design operating conditions. The other panels allow the User to enter the design options for a given application.
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2.10.1.2.1 Setting Up the Design Problem Setting the artificial lift design problems is defining the various parameters in the figure above. These are described below: Design Rate Method ·
Entered By User Use this option when designing for a given production rate and gas lift gas injection rate or when modelling the performance of an existing installation. If Check Conformance with IPR is selected, the program will modify the rate and the gas injection rate, if necessary, to honour the IPR. If a maximum production calculation has been previously done, the lift gas and design production rates can be User Entered. The design rate can be entered either in terms of liquid or oil production only. The design lift gas injection is entered as the Maximum gas available.
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Calculated from Maximum production PROSPER will find the maximum possible oil production rate by determining both the optimum gas injection rate and depth. This is achieved by calculating the oil production for a given GLR injected and increasing the GLR until the optimum is found.
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Calculated from Maximum revenue Using User-entered economic parameters for oil and sales gas revenue, produced water processing and lift gas cost, the program will find the gas lift design that maximises total revenue (oil and gas revenue less water and injection gas processing costs). The same search procedure as for Maximum production is carried out using the cost function in place of the oil production rate. For both Maximum production and Maximum revenue design methods, a maximum liquid rate is required to be input. This allows the User to honour production constraints imposed by surface facilities or off take targets.
Input Parameters Having set up the calculation options, enter values for the following variables on the Input Parameters panel:
Maximum gas available · Set to the maximum gas available at normal operating pressure for maximum rate or revenue methods. ·
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Maximum gas during unloading · Enter the maximum gas available at the unloading pressure for unloading the shallowest valve. Flowing top node pressure · If surface equipment has been entered, this is the manifold pressure · Otherwise, enter the flowing wellhead pressure. Unloading top node pressure · Enter a lower unloading pressure if e.g. the separator is bypassed during unloading · Otherwise leave set the same as flowing top node pressure. Operating injection pressure · Available gas injection system pressure available at the casing head. This is not the final operating injection pressure. · If the Safety equipment option has been selected, pressure losses along surface pipes are computed also. Kick off injection pressure · Leave set to normal injection system pressure unless an auxiliary source of high pressure kicks off gas is available. · This pressure is used to space the first unloading valve. If a sufficiently high pressure is entered, then no unloading valves will be needed. Desired dP across valve · User selected design pressure loss across valve orifice to ensure well and gas injection system pressure stability. Usually in the order of 100200 psi. Maximum Depth of Injection · Constrains the maximum injection depth to be shallower than the production packer. Water cut ·
Design producing water cut.
Minimum Spacing · Sets the minimum spacing between valves. Use 200 - 400 ft normally. Static gradient of load fluid PROSPER Manual
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Density of fluid to be balanced by casing pressure during unloading.
Minimum transfer dP · Only active when Ignoring IPR for Unloading has been selected. If set to zero, unloading valve trims will be sized to inject sufficient gas to lower the unloading tubing pressure to the transfer pressure at the valve depth. · Increasing the value of Minimum transfer dP will lower the unloading GLR injected and reduce trim sizes. Referring to the sketch below, the transfer pressure is: (Pmin) = Ppd - (Ppd - Pid) * % minimum transfer dP /100 Increasing the injection GLR shifts the tubing gradient during unloading closer to the objective gradient line (i.e. to the left). The unloading valve trim is sized for the GLR corresponding to the required transfer pressure. Values of 5 to 25% are commonly used.
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Unloading valve trim sizing depends on whether or not the IPR is used to determine well flow rates while unloading. Existing Users should review this section carefully.
Maximum port size · Depends on valve series selected. PROSPER will select multiple orifice valves for high gas injection rates if the design injection cannot be passed by one valve of Maximum port size. Safety For Closure Of Last Unloading Valve · Extra dP to ensure that the last unloading valve before the orifice is closed Thornhill-Craver ReRating- DeRating Percentage for Valves and for Orifice ·
This coefficient is used to scale down the maximum gas injection rate that can be flowed through a valve or the orifice. As the maximum gas rate is decreased, this means that to flow the same gas rate as the original case (with no de-rating), larger valve or orifice should be used
Valve Type ·
Casing sensitive valves o Enter the minimum casing pressure drop to close valves.
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Tubing sensitive valves o Enter the percentage difference in Pcasing - Pwh to close valves.
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Proportional response valves Proportional o PROSPER determines the closing pressure as part of the design calculations.
Valve Settings (Casing pressure operated valves only) For casing pressure operated valves, there are 3 options for setting valve dome pressures: ·
Pvc = Gas Pressure PROSPER in this case sets valve dome pressures to balance the casing pressure at depth. Unloading valves will close when the casing pressure drops below this value. A small value of Casing Pressure to Close Valves will ensure that the unloading valves will remain shut. This design method ensures maximum injection depth and hence maximises
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production rates. ·
All Valves Pvo = Gas Pressure Dome pressures are set so that valves open with the design casing pressure at depth. The casing pressure must be reduced by at least R(Pvo - Pt) to close valves for this option. PROSPER designs using the maximum of dP to close valves or the calculated closing pressure drop. This method reduces the available injection pressure and will result in lower production rates.
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This is the recommended design setting when designing new wells.
First Valve Pvo = Gas Pressure The first valve dome pressure is set to open on the design casing pressure at depth. Subsequent valves are set to close on design casing pressure. This method gives additional safety for the opening of the first unloading valve without sacrificing available pressure for the deeper unloading valves. Pmin - Pmax Enter fraction of TEF
Injection Point Before the gas lift design is performed, the User can decide if the operating valve is a gas lift valve or an orifice. Dome Pressure Correction above 1200 psi There are two equations for dome pressure temperature correction for dome pressures above 1200 psi. ·
No
PROSPER will use the standard API temperature correction method for all pressures. This method is known to be inaccurate at high pressures. The option is provided for convenience in comparing results from hand calculations etc. ·
Yes The API method is used below 1200 psi, and an improved algorithm is used above 1200 psi. This is the default and recommended option.
Check Rate Conformance with IPR When selected, PROSPER will re-calculate the system solution rate at each step in the design process to ensure that the design rate can be met. This prevents for example, a design being done for an unrealistic Enter by User rate. Ü
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User must be aware that the design rate may not be able to be met by the well. Vertical Lift Correlation Select the most appropriate correlation for the application. Matched VLP correlations should be used when available. Surface Pipe Correlation Select the most appropriate correlation for the application. Surface pipes (when entered in surface equipment) form part of the gas lift system in PROSPER and are accounted for when calculating unloading pressures and flowing pressure losses. This can be important for sub-sea systems where the flow line head can be significant. Using IPR for Unloading ·
Yes This is the recommended PROSPER unloading valve trim sizing method. Unloading valves are sized to achieve a minimum flowing gradient above the valve assuming that the load fluid is being produced. The IPR is used to calculate the well production rates during unloading. Minimum transfer dP (as explained under inputs below) is ignored for this option.
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No This is the standard hand-calculation method. Unloading valve trims are sized to achieve the GLR required to lower the tubing pressure to the transfer pressure. The GLR is based on the full design production rate - the actual production rate during unloading is not calculated. This results in the selection of larger valve trims. Minimum transfer dP is used to increase the transfer pressure, thereby reducing the unloading gas requirement and valve trim size.
Orifice Sizing On Two options are available: · Calculated dP at Orifice · Min dP Across Orifice
2.10.1.2.2 Gas Lift Valve Selection Once the design problem has been set, the next stage is to tell PROSPER the kind of valves that will be picked up from database for design. On the right-hand side of the input Gas Lift Design input screen there is a navigator window that allows selecting the type of valves to use in the design from an internal database. PROSPER Manual
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Please refer to the end of this chapter for an illustration of how to access and edit the database for the gas lift valves
2.10.1.2.3 Performing the Design (New Well) Once the input data has been defined and the valves type selected, click Continue to access the Gas Lift design screen. The following example is for casing sensitive valves:
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A screen similar to that above will be displayed if design for Maximum
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Rate or Maximum Revenue has been selected. If the design rate is Entered by User, the upper (Rate calculation) part of the screen is not displayed. Displaying the Well Performance Curves / Finding Design Rate (New Well) The first step is to find the design production rate. · Click Get Rate. PROSPER will calculate the Gas Lift Performance Curve and determine the optimum Gas Lift injection rate and maximum oil production rate. Ü
The Get Rate process calculates oil production as a function of gas injected.
When the calculations have finished, the results can be displayed in the form of a well performance curve by clicking Plot. A graph similar to the following will appear:
The target design rate and GLR injected can be read off the performance curve plot. The design rate is: ·
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plot, the oil rate corresponding to maximum available gas is taken as design rate. PROSPER will design for the maximum oil production rate entered in the main input screen, if it exceeds the rate calculated from the performance curve. The performance curves can span several flow regimes. Discontinuities in some flow correlations may cause occasional curve fitting problems. In such cases, a correlation such as Hagedorn Brown may give better results.
Calculating Valve Spacing To perform the valve spacing, click Design. ·
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The program will then determine the depth of the operating valve and the spacing for the unloading valves. Depending on the design settings, this will usually take more than one pass. On the first pass, the injection and unloading valve depths are determined assuming no casing pressure drop to close valves. Having determined the number of valves to use, the operating valve depth is revised to reflect the new operating casing pressure. The spacing procedure is repeated using the revised operating casing pressure until the number of unloading valves and their setting depths no longer change. When Check Rate Conformance with IPR is set to Yes, PROSPER recalculates the solution rate and reduces the design rate if necessary. The final design production and Gas Lift injection rates are displayed on the design gradient plot.
Displaying the Position of the Unloading Valves To display the position of the unloading valves and the final design condition, click Plot. A plot similar to the following will be displayed:
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The plot shows the tubing and casing pressure gradients for the design rate plus the position of the operating and unloading valves. The unloading fluid gradients are plotted also. The design data box lists the Actual production and injection rates together with the operating surface casing pressure. Results To display the valve details click Results and the table with the results will be displayed.
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Click on Calculate to calculate the Dome Pressure and the TestRack Opening Pressure (valve setting pressure at 60°C). Ü
The valve depths, tubing pressure, unloading gas injection rate and trim sizes are shown in the left screen panel.
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The Dome pressure corresponds to the Dome Pressure at 60 deg F and not at the valve operating temperature. The test rack opening pressure is calculated using the relationship Ptro = (Pd @ 60 deg F) / (1 – R) Where Ptro = Test Rack Opening Pressure Pd @ 60 deg F = Dome Pressure at 60 deg F. R = Ratio of Port Area to Bellow Area of Valve.
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Valve types are identified as Valve for unloading valves or Orifice for the last mandrel if the injection point is selected as orifice. No opening or dome pressure calculations are made for the orifice.
The design parameters such as valve depth, opening and closing pressures, orifice size etc. are displayed in the table. Use the scroll thumb below the table to scroll right to see items e.g. R-value, not visible in the display window.
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Design Sensitivity on Port Size By selecting Change Valve it is possible to re-calculate the parameters associated to the valve sizes.
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Once a design has been completed, its performance should be checked over the range of expected well conditions. Transfer the gas lift design and valve setting details into Equipment Gas Lift, then use Calculation System to compute sensitivities. Alternatively, Matching Quicklook can be used to evaluate a design.
2.10.1.3Existing Mandrels Design This option enables the User to design gas lifted artificial lift systems for existing installations. To perform the fixed mandrel depth design, click Design | Gas lift design | Existing mandrels. The following input screen will be displayed:
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relating to spacing the valves have been removed.
2.10.1.3.1 Setting Up the Design Problem Setting the artificial lift design problems is defining the various fields in the figure above reported. Ü
Please refer to the previous section for the description of the entry fields.
For this design type options for the choice of the first valve can be selected: First Valve Choice · Completion Fluid to SurfaceUnloading valves will be placed assuming that completion fluid fills up the entire well and thus must be unloaded from the entire well. Ü
This is the most conservative unloading requirement and is the default option. · Completion Fluid Level Calculated PROSPER estimates the standing liquid level from the reservoir pressure and static pressure gradient. Any mandrels that are above this depth will be set with “Dummy valves”.
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This approach can save valves for low pressure reservoirs. The User must be certain that work over fluids can leak off to balance the reservoir pressure
· Minimum Squeeze PI Method (ELF)This method can be used when the well productivity is sufficient to ensure that completion fluids can be squeezed into the formation during unloading. An unloading tubing gradient is calculated by taking the static reservoir pressure and increasing the injected GLR, until the gradient arrives at the design top node pressure. Unloading valves are spaced by comparing this tubing gradient with the available casing pressure at depth. Ü
This method can be used when the well productivity is sufficient to ensure that completion fluids can be squeezed into the formation during unloading.
2.10.1.3.2 Defining the Depths of Existing Mandrels After setting up the input for the design problems, next, click Mandrels and enter the measured depths of the existing gas lift mandrels as in the example shown below. © 1990-2011 Petroleum Experts Limited
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Enter the depth of all mandrels in the well, including those fitted with dummy valves. PROSPER will select the best depths for the operating and unloading valves from this list. When more mandrels are available than needed for the current design, PROSPER will automatically set dummies at the intermediate depths. The valve type initially entered is unimportant. PROSPER will overwrite the valve type when it performs the design.
This table is effectively a list of the potential valve depths and can be used to prepare designs for new wells where equipment limitations determine the available mandrel depths.
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If entries are made in the Casing Pressure drop or Max. Gas Injected fields on the mandrel depth screen shown in the figure above, these values will overwrite the values entered on the main design screen.
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Leave these fields blank to design using the same values of pressure drop or gas injection for each unloading valve.
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The mandrel depths can be picked up from either Matching QuickLook or E quipment Gas Lift using the Transfer button, or entered by hand. The usual PROSPER editing facilities are available for manipulating the table entries.
2.10.1.3.3 Gas Lift Valve Selection Having entered the mandrel depths, select a valve series using the navigator window on the right, as for the Gas Lift Design (New well) case. This will define the set / type of valves that will be used for design. 2.10.1.3.4 Performing the Design (Existing Mandrels) Click Continue to access the gas lift design calculation screen. If a calculated rate design method has been selected, a screen similar to the following will be displayed:
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Displaying the Well Performance Curves / Finding Design Rate (Existing) Click Get Rate, and the program will calculate the Gas Lift Performance Curve and determine the optimum gas injection rate and production rate for the well given the available injection gas rate and pressure limits. Performing the Design To run the design, click on Design. · The design rate calculation begins by selecting a GLR Injected and a low production rate. · A pressure traverse is calculated from the THP downwards using the gas lifted GLR until the casing pressure equals the tubing pressure less the Desired dP across valves. · A check is then made to find the next shallowest mandrel. The traverse is calculated from the next shallowest injection mandrel depth down to the sand face using the non-Gas Lifted fluid gradient. · The IPR and VLP pressures are compared. PROSPER Manual
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The rate is increased and the calculation repeated until an intersection with the IPR (rate solution) is found. The injection GLR is increased until the optimum production rate is found. This procedure ensures that the available mandrel depths are honoured at every calculation step.
Once the calculations have stopped, click Plot to make a plot of the production rate Vs gas injected. It is similar to that of a new well design. Calculating Mandrels with Valves / Displaying their Position The design is performed for the target rate by clicking Design. Once the calculation has finished, the design can be checked graphically by clicking the Plot button to display a plot similar to the following:
The Design proceeds as follows: · The annulus pressure gradient plot begins at the design casing pressure and traverses down to the first valve. · It is then shifted back as the casing pressure is lowered to close the unloading valve. The annulus traverse is recalculated from surface with the reduced pressure and continues down to the next valve and so on until the operating valve depth is reached. · PROSPER will optionally check the design rate for conformance with the IPR and reduce the design rate if necessary. · The design gradient plot shows the Actual design production and Gas Lift injection rates together with the injection pressure at surface while injecting at the © 1990-2011 Petroleum Experts Limited
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orifice. Calculating the Valve Test Rack Setting Pressures (Existing) To display the valve setting calculations, click Results from the Design screen. Click Ca lculate, and PROSPER will determine the dome pressures and test rack setting pressure for the selected valves as in the following example:
Click Calculate to determine the Dome and the TestRack Opening pressure will be updated for the new valve series. ·
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To access parameters such as the transfer pressure and port size, click on the scroll arrow at the bottom of the Input parameters panel. To perform sensitivity calculations for the current design, the valve depths must be transferred to Equipment Gas Lift before making calculations. Based on flowing tubing pressures PROSPER determines the injection point during production. NEW!!! Design Sensitivity on Port Size By selecting Change Valve it is possible to re-calculate the parameters associated to the valve sizes.
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2.10.1.3.5 Valve Spacing Valve spacing is not affected by the choice of unloading method, but the trim size selection depends on whether the well IPR is used for calculating the unloading rate or not. The following discussion refers to casing sensitive valves. ·
For the design rate and GLR injected, a pressure traverse is calculated from the top node (including the flow line, if present) downwards using the gas lifted flowing gradient.
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The injection depth is the depth at which the flowing tubing pressure equals the casing pressure gradient less the design dP loss across the orifice or the Maximum Injection Depth (packer depth), whichever is the shallower. This step establishes the flowing tubing pressure gradient to be used for valve spacing.
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The shallowest unloading valve is placed at the depth that balances the tubing load fluid pressure with the casing pressure (less a 50 psi safety margin) at that depth.
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Further unloading valves are placed by traversing down between the load fluid pressure gradient and gas lifted tubing pressure gradient (calculated for the design gas lifted production rate) lines.
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Valves are placed ever deeper until the inter-valve spacing equals the pre-set minimum, or the maximum injection depth has been reached.
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Once the first pass design is complete, PROSPER re-calculates the flowing gradient tubing using the current operating valve depth. For casing sensitive valves, the valve depths are re-calculated to allow for the casing pressure drop to close valves. The process is repeated until the valve depths no longer change.
When Check Rate Conformance with IPR is set to Yes, the solution rate is checked to ensure that it can be achieved. PROSPER reduces the design rate if necessary and repeats the spacing exercise.
2.10.1.3.6 Designing with Tubing Sensitive Valves Tubing sensitive valves operate with a constant casing pressure and rely on increasing tubing pressure as the well unloads to close the unloading valve and transfer injection to lower valves. ·
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2.10.1.3.7 Spacing Procedure for Tubing Sensitive Valves The injection point is found as for casing sensitive valves by finding the intersection of the minimum tubing gradient line and the casing pressure gradient (less a 50 psi safety margin). The first unloading valve is spaced as for the casing sensitive case. Intermediate unloading valves are spaced by traversing down using the load fluid gradient from the transfer pressure to intersect the casing pressure gradient for the operating injection pressure. The transfer pressure (tubing pressure at which the unloading valve closes) is calculated using the value of % Pcasing -Pwh as follows: ·
The surface pressure corresponding to the specified % difference between the operating tubing and casing pressures is calculated.
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A straight line is extended from this point to intersect the tubing pressure at the injection point. The valve transfer pressure is defined at any depth by this line.
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A small value of % difference results in transfer pressures close to the flowing tubing gradient. While this results in a design with few unloading valves, any small increase in flowing tubing pressure may cause unloading valves to re-open.
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A larger value of % Pcasing -Pwh will increase the transfer pressure further away from the flowing tubing gradient. This provides a greater safety margin against multi-point injection, but requires the unloading valves to be spaced more closely.
Selecting transfer pressures using only the % Pcasing - Pwh straight line can result in shallow valves having a too conservative transfer pressure and the deeper valves may transfer too close to the tubing gradient line. PROSPER adjusts the design transfer pressures so that valves are spaced efficiently while at the same time ensuring a good safety margin against multipoint injection.
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Having performed a design, it is recommended that the Matching Quicklook and Design Gas Lift Diagnostic sections be used to check the design and examine the effect of varying design and producing conditions.
2.10.1.3.8 Proportional Valves Merla proportional valves are a hybrid of tubing- and casing- sensitive characteristics.
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Some points to note about proportional valves are: a) The dome is not charged with any gas. As such dome pressure is 0 psig.
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b) The closing pressure for the valve is provided by a spring which is set to apply a certain compression force. c) The valve stem has a tapered end which fits into the tapered end of the port. d) As such even when the valve is in the open position, the tubing pressure will have an influence on the opening or closing of the valve. Advantages of a Proportional Response Valve: a) Since there is no gas charge, the valve is unaffected by well temperature. As such the design of these valves becomes simpler. Errors due to inconsistent flowing temperature are also eliminated. b) The valves proportional response to production pressure fluctuations makes it automatically maintain tubing pressure gradient and the right gas injection rate. In the database of PROSPER for a Proportional Valve, a number of parameters are required. The following describes these various parameters
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& Ab = Bellow Area), which is calculated from experimental data by solving the valve opening / closing pressure equations. The parameter Fe corresponds to the term R for a Casing Sensitive Valve. b) SMALL, MEDIUM, LARGE: there are three configurations for the same valve. For each configuration a value of Fe and the slope of K and M are defined c) Pcf: this corresponds to the Injection Pressure i.e. the Gas pressure in the casing annulus. d) Pvc: this corresponds to the Spring Adjustment Pressure e) K: this is a correction parameter that is used to quantify the maximum possible rate that can be injected through the valve. f) M: represents the slope of throttling line. (The throttling line represents the rate that can be injected through the valve for reducing values of tubing pressure for a constant Injection pressure) Further information about these various parameters can be found in “Gas Lift Manual” by Gabor Takacs. (PennWell Corp).
2.10.1.4Gas Lift Adjustments The existing Gaslift Design sections allow the User to select and size gas lift equipment for specified design conditions. Gaslift Adjustments provides additional calculations for testing gas lift designs under operating conditions. Surface casing pressures when restarting production are presented in addition to input parameters needed for setting up automatic well controllers. To set up a Gaslift Adjustments calculation, enter the following items:
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These are the required input data: - Downstream Pressure Constraint Surface pressure the well must flow against - Kick off Casing Head Pressure Absolute maximum available casing injection pressure - Lift Gas Network Normal Pressure Normal operating pressure of injection gas system - Safety Margin For Lift Gas Control Control pressure drop across gas injection choke - Maximum CHP Under Normal Operation Injection pressure available downstream of control choke. Difference of network and control pressures. - Min CP decrease to Close Last Unloading Valve Specified pressure drop to close deepest unloading valve - Lift Gas Temperature Temperature of injected gas at the casing head - Target Liquid Production Rate Design production rate for Gaslift adjustments calculations. - Water Cut Design water cut for Gaslift adjustments calculations © 1990-2011 Petroleum Experts Limited
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- Production (Total) GOR Solution and free gas production (does not include injection gas) - Vertical Flow Correlation Select appropriate correlation. Matched correlations should be used where available. - Dome Pressure Correction (above 1200 psig) When Yes is selected, an improved dome pressure correction is used. The API temperature correction is always used below 1200 psi. Once the input data entry is complete, the User has to make sure that the correspondent valves are transferred. Select Valves and then Transfer to transfer the valve info from Gas Lift Design or from QuickLook:
Once the gaslift equipment details are entered the flowing gradient or static gradient can be estimated: Flowing Calculations are made for flowing conditions at the User-entered target production rate. PROSPER calculates well performance curves for gas injection at each mandrel depth. Production rates and pressures at surface and mandrel depth are determined. Annulus volume and bottoms up times are also calculated. The flowing gradient for the operating condition can be plotted with opening and closing pressures for each unloading valve displayed.
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Static Calculations are made for shut-in conditions. The static tubing gradient is determined using the liquid density calculated for the producing water cut. When the reservoir pressure cannot support a full liquid column, a gas gradient is used back to surface.
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The pseudo flowing gradient represents the gradient in the tubing during the unloading process, and corresponds to the point when the FBHP just reduces below the reservoir pressure. In other words, during the unloading process for a well that has been shut in, there will be a point when the FBHP starts reducing below the reservoir pressure and the reservoir starts providing fluid. The pseudo flowing gradient is the gradient in the tubing at that time.
2.10.1.5Gaslift Valve Performance The Valve Performance Clearinghouse (VPC) is a non-profit making organisation formed by a consortium of major oil companies. Its objective is to become a repository for the collection, analysis and distribution of gas lift valve performance data and correlations to member companies and licensees. This information has been made available to Petroleum Experts and a framework to utilise it is included in Prosper in the Gaslift Valve Performance section. The database required to implement this feature is not distributed by Petroleum Experts and must be obtained from the VPC. This implementation consists of two parts · Database inspection and valve performance curve calculation and display · Gaslift Design and QuickLook integration 2.10.1.5.1 Valve Performance Clearinghouse (VPC) Valve Performance Clearinghouse (VPC) PROSPER Manual
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The Valve Performance Clearinghouse (VPC) is a non-profit making organisation formed by a consortium of major oil companies. Its objective to become a repository for the collection, analysis, and distribution of gas lift valve performance data and correlations to member companies and licensees. Tests are conducted at the Southwest Research Institute compliant to the API 11V2 RP specification. Test data and correlations are proprietary to member companies, and are licensed to nonmembers for a fee on a per-valve basis. This information has been made available to Petroleum Experts and a framework to utilise is included in this version of PROSPER. The database required to implement this feature will not be distributed with PROSPER by Petroleum Experts and must be obtained from VPC. The Valve Performance Clearinghouse is a service offered by Decker Technology. Its objectives are · Establish an independent source for the collection, consolidation, and distribution of valve performance data and correlations to members. · Perform tests on gaslift valves selected by the members using the API 11V2 RP · Develop correlations using the Decker Technology proprietary method to predict gas passage for any pressure and temperature conditions with an accuracy of better than +/-20%. · Provide a Valve Performance Reference manual containing performance data and correlations for all valves tested by the VPC. Decker Technology, Inc. 2238 McCurdy Road Stone Mountain, GA 30087 Phone: 770-496-9680 Fax: 770-496-9681 E-mail:
[email protected]
2.10.2 Intermittent Gas Lift Intermittent gas lift may be considered for wells at low reservoir pressure or wells with high pressures but low productivity. The method is transient and complex. Today, the various approaches still rely on approximations and rules of thumb. The following pictures show the various stages of a cycle in intermittent gas lift from the instant the bottom valve opens: Liquid accumulates in the tubing. This is the slug. When the slug reaches a certain size, gas lift enters the tubing and lift the slug to the surface. The static liquid film against the inner diameter of the tubing falls back and the process is repeated.
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PROSPER can be used to design intermittent gas lift systems. For the valves depth estimation two options are currently available: - the constant surface closure method and the - the optiflow design procedure. Please refers to "Gas Lift Manual" by Gabor Takcs, for more details about the theory behind both options. This is the default artificial lift method in gas lifted fields where formation pressures to not allow continuous flow any more. It is also suitable for wells with relatively high formation pressure but low productivity. Method of Operation Lift gas is periodically injected into the well at a depth close to the perforations. This gas is used to displace the column of liquid that accumulated while the gas lift valve was closed. If the correct amount of gas is injected, the liquid slug of oil is lifted to the well head and into the surface flowline. Efficient operation occurs when the slug arrives at the surface intact, in advance of gas bubble breakthrough. Basic Operation of 1 cycle
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A. Operating Valve is closed – formation fluids are accumulating above it. Casing & Tubing pressures at depth increase until desired slug length has accumulated. B. Lift gas is injected at a high instantaneous rate, creating a large gas bubble. C. This gas bubble lifts the slug to surface D. After the slug enters the flow line, high pressure gas produces entrained liquid droplets until pressure falls to separator pressure; the operating valve closes; the standing valve re-opens and the cycle commences again. The Intermittent cycle Accumulation period – starts as soon as the standing valve opens and allows wells fluids to accumulate in the well adding to the slug remaining from the previous cycle of fluid that did not reach surface Injection-lifting period – starts as soon as the gas lift valve opens and gas enters the well and lasts until the slug has completely entered the flowline After flow period – when the slug leaves the wellhead, the well contains high pressure gas column with entrained liquid droplets and the high velocity gas also lifts part of the liquid film wetting the tubing inside wall – thus adding to the amount of well fluid produced. This period ends when the decreasing gas pressure allows the standing valve to re-open and the accumulation period commences again. During the whole of the lifting period, the slug length is reduced by liquid fallback and © 1990-2011 Petroleum Experts Limited
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gas breakthrough. Since the lifting of liquid slugs in intermittent gas lift is a transient process – accurate analytical solutions do not exist. The approaches used require some assumptions. Daily Production = Production per cycle * no. of cycles per day Slug length is user-determined, but one should consider that a long slug requires a long production time and fewer cycles per day, whereas a shorter slug length allows more cycles per day. This relationship is not necessarily linear. In practise, it has been found that maximum daily production is obtained when a starting slug length equal to 40-50% of the static liquid column is used. Liquid FallBack This needs to be determined in order to be able to design an accurate Intermittent Gas Lift installation. Empirical studies of liquid slug and gas bubble velocity (e.g. White et al JPT 1963) showed that gas velocity was fairly constant whereas slug velocity varies with the ratio of injection and production pressures but reaches an essentially constant value very rapidly. Liquid fallback is minimised if slug velocity is maximised. Liquid Fallback is determined by
FB =
D æ Vs ö 1+ ç ÷ è Vb ø
Bubble velocity is assumed constant and slug velocity is determined by solving simultaneously, the flow rate through an orifice and the equation of the forces acting on a liquid slug in motion up the tubing.
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Valve Spacing In order to use normal gas lift pressure, it is usually necessary to design a valve unloading string to allow the stepwise transfer of the injection point from the surface down to the operating valve Constant surface closing pressure – commonly used for single-point injection systems assumes a constant surface closing pressure for all valves in the unloading valve string Optiflow design procedure – is suited for wells with poor information on well potential. Assuming that the operating point as well as the production rate are unknown this permits injection of gas at the deepest possible point at all times. This is done by moving the operating point down the well such that the inflow is sufficient to prevent operation of the next lower valve. Assumes 50% of the lift gas pressure at depth as the tubing pressure at each valve depth.
2.10.3 Electrical Submersible Pump Design The Design Electrical Submersible Pump section allows the User to design an ESP installation. The design is performed in two steps: 1. Determine the required pump head to achieve a specified production rate © 1990-2011 Petroleum Experts Limited
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2. Select a suitable combination of pump, motor and cable for the application. ESP data entered in the System Electrical Submersible Pumps input menu is not utilised by the ESP design section. The design results will overwrite this section. In the main ESP Design screen the design parameters can be entered:
The parameters are self-explanatory, except for the four parameters: · Gas Separator Efficiency It represents the efficiency of separation of gas in case there is free gas and a downhole separator is installed · Motor Power Safety Margin This factor adds a safety margin to the power strictly necessary to lift the design rate. For example, if the safety margin is 10%, the pump power requirement will be increased of 10% · Pump Wear Factor This factor takes in account of the deterioration of the pump performance. A wear factor of 0.1 will scale the original head as per performance curve of 10% PROSPER Manual
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· Gas DeRating Model It allows selecting a User DeRating model. The Gas Derating model will consider the reduction in the pump's performance when free gas enters the pump. The Derating model represents the relation between the quantity of free gas and the amount by which the pump's performance reduces. The User has the ability to import a DeRating model in the form of a custom .dll file. This can be done by clicking on File | User Correlation | HSP Gas Derating model. The model imported in this section will also be applicable for ESP design. Design procedure Designing an ESP installation using PROSPER is divided into two phases: 1. Calculate This is where the head and power requirement calculations are made and 2. Design This is where, on the basis of the calculations, the equipment is selected. The following description assumes that input of the well details and PVT data have already been correctly completed and that where applicable, pressure drop correlations have been matched to field data. 2.10.3.1ESP Calculate This section determines the head required to be supplied by the pump to achieve a specified production rate. From the main ESP Design screen select Calculate:
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Clicking on Calculate the program calculates the pump duty necessary to achieve the design production rate. PROSPER will display the pump duty solution, as shown in the figure above. ·
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PROSPER uses the IPR from System Inflow Performance to calculate the flowing pressure at the sand face and the specified VLP correlation to find the pump intake pressure for the design production rate. The program then works down from the specified top node pressure to arrive at the required pump discharge pressure. The difference between the intake and discharge pressures represents the required pump head. PROSPER compresses the liquid and gas as the pressure increases across the pump, so the volumetric rate will be less at the discharge than at the pump inlet. The mass flow rate and the required head are used to determine the pump fluid power requirement. Emulsions If Emulsions have been selected on the Options screen, viscosity corrections are applied to pump capacity and head. Otherwise, no ESP viscosity corrections will be applied. If an Emulsion PVT model has been built in the PVT section, then the emulsion viscosity can be optionally used in the ESP calculations and elsewhere. As mentioned in the PVT section, emulsion behaviour in oilfield systems analysis is poorly understood. The emulsion PVT
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model provides the means to apply empirical corrections and should be used with caution.
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If an inlet gas separator is to be used, enter the separator efficiency before carrying out the calculation. The program allows the percentage of free gas set by the separator efficiency to be produced up the annulus, and the remainder to be compressed through the pump. Hence, the PVT properties of the well fluids can be different below and above the pump.
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For wells where the ESP pump is landed high up in the well it is possible that the fluid can not reach the pump intake. For such cases, PROSPER will report a Pump Intake Pressure (PIP) of 10 psi. Therefore the user should be cautious when the calculated PIP = 10 psi as this indicates that the fluid can not reach the pump intake and the design can not be completed.
2.10.3.1.1 Checking Suitability of Separator Efficiency Ü
To check that the separator efficiency chosen in the input is acceptable for the design case, the Dunbar Criterion may be used as showed below.
Click Sensitivity to display the intake pressure and intake GLR plotted over a range of gas separator efficiency curves. Check that the design operating point lies above the empirical limit represented by the Dunbar Factor line.
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2.10.3.2ESP Design (Pump, Motor and Cable Selection) Having determined the required pump duty, click on Done to go back to the ESP design screen. The next step is to select the pump, motor and cable capable to provide the calculated duty. To do so, select Design; the program will display a pump design screen similar to that shown below:
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In the Select drop-down boxes, PROSPER lists the equipment in its database that is capable of meeting the design requirements. Select Pump PROSPER presents pumps that can meet the following criteria: · · · ·
Inlet rate within range Discharge rate within range Head developed at design well rate is near pump's maximum efficiency point Pump O.D. < Casing I.D.
The User must select a pump from those listed. Select Motor Once a pump has been selected, the pump efficiency is known; the motor power requirement can now be calculated. Proceed to the motor drop-down box and select a motor from those listed. Ü
PROSPER lists pumps and motors on the basis of diameter and performance characteristics.
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It is the User's responsibility to ensure that the pump selected is coherent with the information provided by the manufacturer It is the User's responsibility to ensure that the motor selected is physically compatible with the pump and that the most economical combination of operating voltage and current is chosen. Select Cable Once the motor power and voltage option have been determined, a suitable cable must be selected. PROSPER displays those cables capable of passing the required current.
2.10.3.2.1 Checking the Pump Design Click Plot to display the design operating point on the pump performance curve as shown below:
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Normally, the first pass design will have an operating point fairly close to the selected pump's optimum efficiency. However, as well conditions change with time, this may not be the best design for the life of the installation ·
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the ESP design section until an optimum design is obtained. A report can be generated which gives details of the pump selection and design conditions The robustness of the first pass design must then be checked over the range of expected well operating conditions by running System sensitivities in the C alculation menu PROSPER allows sensitivities to be run on both well performance and pump parameters such as pump setting depth and operating frequency
The ESP system design process is completed by iterating between the Calculation and Design sections until the final design is optimised over the projected pump run life. Viscosity corrections, where applicable, will be considered in choice of available pumps and the number of stages required.
2.10.4 Hydraulic Pump Design The Design Hydraulic Pump section allows the User to design a HSP installation. The design is performed in two steps: 1. Determine the required pump head to achieve a specified production rate (reservoir fluid + power fluid) 2. Select a suitable combination of pump and turbine for the application HSP data entered in SystemïHydraulic Submersible Pumps is not utilised by the HSP design section and will be overwritten by the design. In the main HSP Design screen the design parameters can be entered:
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The parameters are self-explanatory, except for the three parameters: ·
% Power Fluid of Reservoir Fluid This factor represents the ratio (in %) between the power fluid and the produced reservoir fluid. A value of 100% means that the rate of power fluid is equal to the rate of produced reservoir fluid · Pump Wear Factor This factor takes in account of the deterioration of the pump performance. A wear factor of 0.1 will scale the original head as per performance curve of 10% · Gas DeRating Model It allows selecting a User DeRating model. The Gas Derating model will consider the reduction in the pump's performance when free gas enters the pump. The Derating model represents the relation between the quantity of free gas and the amount by which the pump's performance reduces. The User has the ability to import a DeRating model in the form of a custom .dll file. This can be done by clicking on File | User Correlation | HSP Gas Derating model.
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Design procedure The design of an HSP installation using PROSPER is divided into two phases. One is where the head and power requirement calculations are made and the second part is where on basis of the calculations, the equipment is selected. The following description assumes that input of the well details and PVT data have already been correctly completed and that where applicable, pressure drop correlations have been matched to field data.
2.10.4.1HSP Calculate This section determines the head required to be supplied by the pump to achieve a specified production rate. From the main HSP Design screen select Calculate:
Clicking on Calculate the program calculates the pump duty necessary to achieve the design production rate. PROSPER will display the pump duty solution, as shown in the figure above. ·
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· · ·
The difference between the intake and discharge pressures represents the required pump head. PROSPER compresses the liquid and gas as the pressure increases across the pump, so the volumetric rate will be less at the discharge than at the pump inlet. The mass flow rate and the required head are used to determine the pump fluid power requirement.
For certain configurations the produced and power fluids can be commingled above the pump. Hence, the PVT properties of the well fluids can be different below and above the pump. Emulsions Ü If Emulsions have been selected on the Options screen, viscosity corrections are applied to pump capacity and head. Otherwise, no HSP viscosity corrections will be applied. If an Emulsion PVT model has been built in the PVT section, then the emulsion viscosity can be optionally used in the HSP calculations and elsewhere. As mentioned in the PVT section, emulsion behaviour in oilfield systems analysis is poorly understood. The emulsion PVT model provides the means to apply empirical corrections and should be used with caution.
2.10.4.2HSP Design (Pump and Turbine Selection) Having determined the required pump duty, click on Done to go back to the ESP design screen. The next step is to select the pump, motor and cable capable to provide the calculated duty. To do so, select Design: the program will display a pump design screen similar to that shown below:
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In the Select drop-down boxes, PROSPER lists the equipment in its database that is capable of meeting the design requirements. Select Pump PROSPER presents pumps that can meet the following criteria: · · · ·
Pump Speed within range Discharge rate within range Head developed at design well rate is near pump's maximum efficiency point Pump and O.D. < User input maximum
The User must select a pump from those listed. Select Turbine Once a pump has been selected, the pump efficiency is known, so the turbine power requirement can now be calculated. Proceed to the turbine drop down box and select a turbine from those listed. Ü
PROSPER lists pumps and motors on the basis of diameter and performance characteristics. It is the User's responsibility to ensure that the pump selected is coherent with the information provided by the manufacturer
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It is the User's responsibility to ensure that the motor selected is physically compatible with the pump and that the most economical combination of operating voltage and current is chosen.
2.10.4.2.1 Checking the Pump/Turbine Design Click Pump and Turbine Plot to display the design operating point on the pump performance curve as shown below:
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Normally, the first pass design will have an operating point fairly close to the selected pump's optimum efficiency. However, as well conditions change with time, this may not be the best design for the life of the installation. Different combinations of pump and turbine can be quickly experimented with in the HSP design section until an optimum design is obtained. A report can be generated which gives details of the pump selection and design conditions. Important Note The robustness of the first pass design must then be checked over the range of expected well operating conditions by running sensitivities in the System Calculation menu. To access the System Calculation, select the System button within the HSP design section.
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This is a specialized form of the calculation that ensures that the power generated by the turbine is equal to the power required by the pump. This is achieved by varying the power fluid injected until this requirement is met. The calculation is therefore somewhat slower than the normal system calculation. The HSP system design process is completed by iterating between the Calculation and Design sections, until the final design is optimised over the projected pump run life. Viscosity corrections, where applicable, will be considered in choice of available pumps and the number of stages required.
2.10.5 Progressive Cavity Pump Design The DesignïProgressive Cavity Pump section allows the User to design a PCP installation. The design is performed in two steps: 1. Determine the required pump head to achieve a specified production rate 2. Select a suitable combination of pump and turbine for the application PCP data entered in SystemïHydraulic Submersible Pumps is not utilised by the PCP design section and will be overwritten by the design. In the main PCP Design screen the design parameters can be entered:
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This is the case of PCP with Sucker Rod. If the PCP is driven by a Downhole Motor, the data to input are similar to the ones seen in the ESP. All the parameters are self-explanatory on the basis of the previous sections. Design Procedure The design of an PSP installation using PROSPER is divided into two phases. One is where the head and power requirement calculations are made and the second part is where on basis of the calculations, the equipment is selected. The following description assumes that inputs of the well details and PVT data have already been correctly completed and that where applicable, pressure drop correlations have been matched to field data. 2.10.5.1PCP Calculate This section determines the head required to be supplied by the pump to achieve a specified production rate. From the main PCP Design screen select Calculate:
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Clicking on Calculate the program calculates the pump duty necessary to achieve the design production rate. PROSPER will display the pump duty solution, as shown in the figure above. ·
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PROSPER uses the IPR from System Inflow Performance to calculate the flowing pressure at the sand face and the specified VLP correlation to find the pump intake pressure for the design production rate. The program then works down from the specified top node pressure to arrive at the required pump discharge pressure. The difference between the intake and discharge pressures represents the required pump head. PROSPER compresses the liquid and gas as the pressure increases across the pump, so the volumetric rate will be less at the discharge than at the pump inlet. Emulsions If Emulsions have been selected on the Options screen, viscosity corrections are applied to pump capacity and head. Otherwise, no HSP viscosity corrections will be applied. If an Emulsion PVT model has been built in the PVT section, then the emulsion viscosity can be optionally used in the HSP calculations and elsewhere. As mentioned in the PVT section, emulsion behaviour in oilfield systems analysis is poorly understood. The emulsion PVT model provides the means to apply empirical corrections and should be used with caution.
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2.10.5.2PCP Design (Pump and Rod Selection) Having determined the required pump duty, click on Done to go back to the PCP design screen. The next step is to select the pump, motor and cable capable to provide the calculated duty. To do so, select Design: the program will display a pump design screen similar to that shown below:
In the Select drop-down boxes, PROSPER lists the equipment in its database that is capable of meeting the design requirements. In the case of motor driven PCP, motor and cable will have to be selected. Ü
PROSPER lists pumps and motors on the basis of diameter and performance characteristics. It is the User's responsibility to ensure that the pump selected is coherent with the information provided by the manufacturer It is the User's responsibility to ensure that the motor selected is physically compatible with the pump and that the most economical combination of operating voltage and current is chosen.
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As seen for ESP and HSP installations, the PCP design should be checked by performing sensitivities in System Calculation, in order to verify the design against the expected change of conditions along the life of the well.
2.10.6 Coiled Tubing GasLift Design The DesignïCoiled Tubing GasLift section allows the User to perform a design of gas lift using coiled tubing. Before performing the design, data concerning the gas lift gas and the coiled tubing equipment should be entered in the Coiled Tubing Data screen, accessible from the S ystem menu:
Then select DesignïCoiled Tubing GasLift:
The input data and the options to enter in this screen are exactly the same as for the normal Gas Lift Design (design for a User Entered Rate, or for Maximum Production, © 1990-2011 Petroleum Experts Limited
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etc). Please refer to the Gas Lift Design section for a detailed explanation. To perform the Design, select Continue. This will access a screen similar to the Gas Lift Design:
In the case of the figure above, select Get Rate to calculate the Gas Lift Performance Curve and then Design to perform the design. The program will determine the maximum injection depth, the rate produced and the gas to inject. The Plot feature allows visualising the design:
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2.10.7 Jet Pump Design The Design Jet Pump section allows the User to design a Jet Pump installation. The design is performed in two steps: 1. Determine the required pump head to achieve a specified production rate 2. Select a suitable pump for the application Jet Pump data entered in System/Jet Pumps is not utilized by the design section and will be overwritten by the design. In the main Jet Pump Design screen the design parameters can be entered:
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The input data are self-explanatory. As far as the loss coefficient are concerned, these coefficients are a measure of the energy loss due to the friction in the above quoted sections of the pump. The coefficients are provided by the Jet Pump manufacturers. Design Procedure The design of a Jet Pump installation using PROSPER is divided into two phases. One is where the head and power requirement calculations are made and the second part is where on basis of the calculations, the equipment is selected. The following description assumes that inputs of the well details and PVT data have already been correctly completed and that where applicable, pressure drop correlations have been matched to field data. 2.10.7.1Jet Pump Calculate This section determines the head required to be supplied by the pump to achieve a specified production rate. From the main Jet Pump Design screen select Calculate: PROSPER Manual
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Clicking on Calculate the program calculates the pump duty necessary to achieve the design production rate. PROSPER will display the pump duty solution, as shown in the figure above. ·
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PROSPER uses the IPR from System Inflow Performance to calculate the flowing pressure at the sand face and the specified VLP correlation to find the pump intake pressure for the design production rate. The program then works down from the specified top node pressure to arrive at the required pump discharge pressure. The difference between the intake and discharge pressures represents the required pump head. PROSPER compresses the liquid and gas as the pressure increases across the pump, so the volumetric rate will be less at the discharge than at the pump inlet. According to the Surface Fluid (the Power Fluid) Injection Rate and Injection Pressure, the program will determine R (ratio between the areas of the nozzle and of the throat), the diameter of the throat and the diameter of the nozzle Emulsions If Emulsions have been selected on the Options screen, viscosity corrections are applied to pump capacity and head. Otherwise, no HSP viscosity corrections will be applied. If an Emulsion PVT model has been built in the PVT section, then the emulsion viscosity can be optionally used in the HSP calculations and elsewhere. As mentioned in the PVT section, emulsion © 1990-2011 Petroleum Experts Limited
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behaviour in oilfield systems analysis is poorly understood. The emulsion PVT model provides the means to apply empirical corrections and should be used with caution.
2.10.7.2Jet Pump Design (Pump Selection) Having determined the required pump duty, click on Done to go back to the Jet Pump design screen. The next step is to select the pump suitable to provide the calculated duty. To do so, select Design: the program will display a pump design screen similar to that shown below:
Select a pump from the database whose Actual performance (in green in the figure above) is close to the Desired performance. PROSPER Manual
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PROSPER lists pumps on the basis of diameter and performance characteristics. It is the User's responsibility to ensure that the pump selected is coherent with the information provided by the manufacturer
As seen for ESP, HSP and PCP installations, the Jet Pump design should be checked by performing sensitivities in System Calculation, in order to verify the design against the expected change of conditions along the life of the well.
2.10.8 Sucker Rod Pump Design 2.10.8.1Background General hints The schematic of a conventional Sucker Rod Pump installation is sketched in the following figure along with the downhole pump:
Working principle: A prime motor moves the gearbox, which rotates the crank. The crank is attached to a counterweight and is connected to the Pitman arm. The Pitman arm is then connected to the walking beam.
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The rotary movement of the crank is propagated and translated into a reciprocating movement of the rod connected to the downhole pump. From the figure above it is possible to see that as the crank rotates, the rod shifts the plunger up (upstroke) and down (downstroke) in the pump barrel. The downhole pump is composed of a barrel with a ball-and-seat valve at the bottom (standing valve) and a plunger with another ball-and-seat valve (traveling valve). During the downstroke the plunger is lowered in the barrel, the traveling valve is opened and standing valve is closed; in this way the fluid is displaced in the tubing above the plunger. During the upstroke, the traveling valve is closed, whilst the standing valve is opened, letting the fluid flow from the formation into the barrel. The fluid that was in the tubing in the previous step is pushed towards the surface.
Troubleshooting the performance of the Pump It is possible to monitor the pump performance by measuring the variation of the rod load against the position of the rod itself by means of a dynamometer. The resulting plot is called "dynamometer card". This plot is a very useful method to PROSPER Manual
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verify that the pump is working fine and to diagnose eventual problems. The example reported below illustrates the shape of a dynamometer card for the ideal case of pump and rod perfectly rigid, no friction, perfect pump action:
With reference to the figure above: - Point A: the plunger is in the lowest point. This is the starting point of the upstroke - A-B: The traveling valve closes and the standing valve opens. As this is an ideal case, the total load of the fluid above the plunger is taken over by the sucker rod - B-C: The plunger travels all the way to the highest point the distance between points B and C represents the stroke length - C-D: The traveling valve opens and the standing valve closes. This is the starting point of the downstroke. The rod unloads - D-A: The plunger travels back to the lowest point of the stroke A As mentioned above, the dynamometer illustrated in the figure represents an ideal situation. However, the examination of actual dynamometer cards allows the Engineer to identify problems related to pump operative problems, like leaking valves, fluid pounding, gas locking, etc. Details about the use of dynamometers cards for pump performance diagnostics can be found in the references reported in Appendix A.
Design
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The design of a Sucker Rod Pump installation is a trial and error procedure that consists of: - starting from assumptions on the pump hardware (pump and rod type, depth, size), flow conditions and design stroke rate or production rate, and then - determining the operating parameters, like: pump displacement, peak polished rod load, minimum polish rod load, peak torque, polished rod horsepower, counterbalance effect (CBE) etc. - verifying how the pump installation behaves through the dynamometer card and torque chart This is achieved by solving the wave equation: 2 ¶ 2 u(x, t) ¶u(x, t) 2 ¶ u(x, t) = a c +g ¶t 2 ¶x 2 ¶t
Solutions to this equation have been provided by Gibbs (ref. Appendix A). The solutions to the equation above allow to determine the surface and downhole dynamometer card and then a torque analysis can be performed to determine the torque. These diagnostic plots can be used to verify the working conditions of the designed pump and sucker rod and in the case the design can be reviewed by changing assumptions and restarting the design.
2.10.8.2Design Sucker Rod Pump The DesignïSucker Rod Pump section allows the User to perform a design of a sucker rod pump installation. Also, along with the design, a series of diagnostic plots (the Dynamometer card, the Torque and Rod Speed plot) are provided, which can be used to verify the actual pump operating regime and in the case troubleshoot the design itself. The design consists of the following steps: 1. Enter design input parameters (PVT, pump data, design input data) 2. Perform the design 3. Perform Rod Sensitivity
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2.10.8.2.1 Enter Design Parameters The input parameters consist of: PVT Data These are the PVT data for the fluid Calculation Mode This option allows to select the design mode: - Enter Stroke Rate, calculate Production Rate - Enter Production Rate, calculate Stroke Rate Pumping Unit and Rod Selection These options allow to specify the pump and the rod specifications to use for the design Service Factor - Non-Corrosive - Salt Water - Hydrogen Sulphide Pump Intake Pressure © 1990-2011 Petroleum Experts Limited
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Allows to select the method used to calculate the pump intake pressure: - Entered Value - Calculated from IPR - Calculated from Fluid Level Design Input These inputs specify the design operating conditions (flowing wellhead and bottomhole temperature, wellhead pressure, pump characteristics and efficiencies, pump position) 2.10.8.2.2 Perform Design After entering the input data, select Calculate to perform the design of the Sucker Rod Pump. The program will calculate the production rate and all the information related to rod load, torque, stress, etc. On the right hand side of the screen the plots related to Rod Load, Torque and Pump velocity are reported.
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The Top Rod Loading and Top Rod % Of Goodman Diagram are measurements of the stress in the top rod based upon the peak polished rod load and the cross-sectional area of the top rod. The API RP11BR discusses the Modified Goodman Diagram and its construction. PROSPER is painting in red those parameters if they exceed 100% and there are basically 2 ways of lowering those values below 100%, 1 is to increase the area of the sucker rods, 2 is to reduce the peak load. The Index of Torsional Effectiveness (ITE) is a measurement of the ability of the beam pump unit type to smooth out and idealize the net crankshaft torque load (under normal conditions handling a full pump barrel of incompressible fluid). The ITE is ratio of the average net torque to the peak net torque expressed as percentage. The higher the ITE the more effective the unit geometry in converting the polished rod load into a smoother and more ideal torsional load. ITE
Beam Pump Performance
Under 15%
Very Poor
20-25%
Fair
25-30%
Average
30-35%
Good
35-40%
Very Good
Unit
2.10.8.2.3 Rod Sensitivity This option allows to perform design sensitivities changing the rod type, in other words, verifying the impact of different rod types on the pump performance:
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The Chart can be plotted in form of bars or pie and different visualisations are available: · Production Rate by Rod Type · HorsePower Required by Rod Type · Production Rate Per HorsePower by Rod Type
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2.10.9 Artificial Lift Database The Artificial Lift Database contains all the information concerning the artificial lift equipment used in PROSPER. This is the content of the Database: ·
Gas Lift Valves
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ESP pumps, motors, cables
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HSP pumps and turbines
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PCP pumps, sucker rods, motors, cables
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Jet pumps
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MultiPhase pumps
In the following sections there is a description of the information stored in the Artificial Lift Database and how to update with new data. To access the database select DesignïDatabase. The Options tab screen collect information on the location of the database and its version:
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An initial database is distributed along with the software. Ü
EQUIPMENT DATABASE DISCLAIMER Every effort is made to ensure that the sample equipment databases supplied are correct. However, it is the User’s responsibility to ensure they are both accurate and up-to-date. For critical design work, always refer to the equipment supplier for the latest performance data. To improve the quality of the Artificial Lift Database, Petroleum Experts is more than happy to accept the contribution of Users who have updated data
2.10.9.1Gas Lift Valve Database To perform a Gas Lift design, PROSPER must have appropriate valve data loaded in its database. To enter and maintain the valve data that PROSPER requires for Gas Lift design, the Gas Lift tab button in the Database:
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The database is completely editable: it is possible to Add, Amend or Delete any record. It is also possible to Export the database to different locations (file, spreadsheets, etc.) or create an Import file. The last option allows to create back-ups of the database in format .GLD, which can be recalled by PROSPER to restore the database using the Import button.
2.10.9.1.1 Adding a New Valve To add a gas lift valve select Add. An entry screen is displayed, where the valve specs can be entered:
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the data to enter are: manufacturer, valve type, Type, Specification, Port size, R value. Ü
The sample gas lift valve database is provided to allow the User to run the examples. Before designing for field installation, the User must first ensure that the database contains current and accurate valve characteristics.
2.10.9.2ESP Database The ESP Database contains the performance curves of pumps and motors and the characteristics of the cables. 2.10.9.2.1 Pump Database Select the tab screen ESP in the Database to access the ESP database:
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The performance curves are provided in the form of coefficients for a polynomial equation fitted to actual performance data. The database is completely editable: it is possible to Add, Amend or Delete any record. It is also possible to Export the database to different locations (file, spreadsheets, etc.) or create an Import file. Selecting a pump and then Plot, the performance curve of the pump is plotted:
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Click Variables to select between Head, Horsepower and Efficiency for plotting.
2.10.9.2.1.1 Adding a New Pump
To add a new pump select Add and enter the required information:
Next step is to enter the performance data for head and power as per manufacturer’s performance curves and fit them to a polynomial. To do so, select Head Coefficients and HP Coefficients and enter the data:
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Then Fit to regress and calculate the polynomial coefficients, then Done to go back to the previous panel. The coefficients have been transferred:
The HP coefficients can be calculated in the same way. Ü
To prevent errors, it is recommended that a plot be made and checked against published curves whenever new data is entered or alterations are made to existing entries.
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2.10.9.2.2 Motor Database To access the Motors section select the tab screen Motors:
Motor characteristics are entered in form of polynomials fitted to performance data. Coefficients are required for Nameplate Amps, RPM, and Efficiency and Power factor. Available horsepower and Power options are entered by clicking the relevant Edit button. Ü
As plotted, motor speed curves may exceed synchronous speed at low % power values. This is a characteristic of the polynomial fitting technique used. The accuracy of motor (and pump) performance curve fits is optimised in the usable efficiency range.
An example of a motor efficiency plot is shown below:
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2.10.9.2.2.1 Adding a New Motor
To add a new motor select Add and enter the required info in the Motor Data:
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Enter the data and fit the polynomials by selecting the buttons NamePlate AMPS, Speed, Efficiency and Power Factor. Use Fit to determine the polynomial coefficients. On the right hand side of the screen above (Power Options) enter the different Power, Voltage and Current the motor is compatible with.
2.10.9.2.3 Cables Database To access the Cables section select the tab screen Cables:
2.10.9.2.3.1 Adding a New Cable
Only a few data about the electric characteristic of the cable are required. Select Add to add a new cable:
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Every effort is made to ensure that the sample equipment databases supplied are correct. However, it is the User’s responsibility to ensure they are both accurate and up-to-date. For critical design work, always refer to the equipment supplier for the latest performance data.
2.10.9.3HSP Database The HSP Database contains the performance curves of pumps and turbines.
2.10.9.3.1 Pumps Database Select the tab screen HSP in the Database to access the HSP database:
The performance curves are provided in the form of coefficients for a polynomial equation fitted to actual performance data. The database is completely editable: it is possible to Add, Amend or Delete any record. It is also possible to Export the database to different locations (file, spreadsheets, etc.) or create an Import file. Clicking on Plot displays the Pump performance curve: © 1990-2011 Petroleum Experts Limited
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2.10.9.3.2 Adding a New Pump To add a new pump or a turbine, the steps to follow are exactly the same seen for ESP pumps. Please refer to the previous section for the details.
2.10.9.3.3 Turbines Database Select the Turbines tab button to display the Turbines Database:
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The performance data are provided as polynomials fitted to performance data.
2.10.9.3.4 Adding a New Turbine To add a new pump or a turbine, select Add and enter the required data:
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The Turbine performance is entered by selecting Add in the Turbine Settings area. The steps to enter the performance data and fit them to a polynomial are the same as seen in the ESP section. Refer to that section for details.
Ü
Every effort is made to ensure that the sample equipment databases supplied are correct. However, it is the User’s responsibility to ensure they are both accurate and up-to-date. For critical design work, always refer to the equipment supplier for the latest performance data.
2.10.9.4PCP Database The PCP Database contains data concerning the performance of pumps and the characteristics of sucker rods, motors and cables. 2.10.9.4.1 Pumps Database Select the tab screen PCP in the Database to access the PCP database:
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In the database parameters concerning the pump configuration are stored. The database is completely editable: it is possible to Add, Amend or Delete any record. It is also possible to Export the database to different locations (file, spreadsheets, etc.) or create an Import file. Clicking on Plot displays the Pump performance curve:
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2.10.9.4.1.1 Adding a New Pump
To add a new pump select Add and enter the required data as per manufacturer’s specs:
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The Optional Data input section in the above screen shot is used to calculate the frictional torque and shaft axial load. If no data is input in the optional data section, results will not be displayed for the given parameters.
Ü
The "Optional Data" may be proprietary, and can be obtained from the given pump manufacturer.
2.10.9.4.2 Sucker Rods Database Select the Sucker Rods tab button to display the correspondent database:
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2.10.9.4.2.1 Adding a New Sucker Rod
To add a new sucker rod select Add and enter the required data:
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As far as motor and cables are concerned, please refer to the ESP section for details.
Ü
Every effort is made to ensure that the sample equipment databases supplied are correct. However, it is the User’s responsibility to ensure they are both accurate and up-to-date. For critical design work, always refer to the equipment supplier for the latest performance data.
2.10.9.5Jet Pumps Database The Jet Pumps Database contains the characteristics of the pumps. 2.10.9.5.1 Pumps Database Select the tab screen Jet in the Database to access the Jet Pump database:
In the database parameters concerning the pump configuration are stored. The database is completely editable: it is possible to Add, Amend or Delete any record. It is also possible to Export the database to different locations (file, spreadsheets, etc.) © 1990-2011 Petroleum Experts Limited
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or create an Import file.
2.10.9.5.1.1 Adding a New Pump
To add a new pump select Add and enter the required data as per manufacturer’s specs (nozzle and throat sizes, minimum and maximum rates, etc.):
Ü
Every effort is made to ensure that the sample equipment databases supplied are correct. However, it is the User’s responsibility to ensure they are both accurate and up-to-date. For critical design work, always refer to the equipment supplier for the latest performance data.
2.10.9.6MultiPhase Pumps Database The MultiPhase Database contains the characteristics of the FRAMO Pumps.
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2.10.9.6.1 Pumps Database Select the tab screen MultiPhase in the Database to access the FRAMO Pumps database:
In the database parameters concerning the pump configuration are stored. The database is completely editable: it is possible to Add, Amend or Delete any record. It is also possible to Export the database to different locations (file, spreadsheets, etc.) or create an Import file. Clicking on Plot, the performance curves of the pump are displayed:
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2.10.9.6.2 Adding a New Pump To add a new pump select Add and enter the required data as per manufacturer’s specs (nozzle and throat sizes, minimum and maximum rates, etc.):
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Every effort is made to ensure that the sample equipment databases supplied are correct. However, it is the User’s responsibility to ensure they are both accurate and up-to-date. For critical design work, always refer to the equipment supplier for the latest performance data.
2.10.9.7Sucker Rod Pump The Sucker Rod Pumps Database contains the characteristics of pumps and sucker rods. 2.10.9.7.1 Pump database Select the tab screen SRP in the Database to access the Sucker Rod Pump database:
In the database parameters concerning the pump configuration are stored. The database is completely editable: it is possible to Add, Amend or Delete any record. It is also possible to Export the database to different locations (file, spreadsheets, etc.) or create an Import file. © 1990-2011 Petroleum Experts Limited
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2.10.9.7.1.1 Adding a New Pump
To add a new pump select Add and enter the required information:
The following schematic illustrates the above required inputs:
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2.10.9.7.2 Sucker Rods Database Select the Sucker Rods tab button to display the correspondent database:
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2.10.9.7.2.1 Adding a New Sucker Rod
To add a new sucker rod select Add and enter the required data:
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Every effort is made to ensure that the sample equipment databases supplied are correct. However, it is the User’s responsibility to ensure they are both accurate and up-to-date. For critical design work, always refer to the equipment supplier for the latest performance data.
2.11 Output The Output menu is used to report, export and plot input data entered into PROSPER and the results generated by the various calculation options in the program: ·
Report This option generates reports about input data and results
·
Export This option transfers input data and results to different locations (printer, spreadsheets, screen, etc.)
·
Plot This option generates plots for input data and results
These functions are available also in any of the input/output screens of the program.
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2.11.1 Report The Report option is used to prepare reports and plots from a current analysis. This section describes how to use the reporting system with the templates provided with the system and how to customise these templates.
2.11.1.1Setting Up the Reporting System The set up of the reporting system begins with defining the default locations where the reports will be created. To define the directories, select File|Preferences:
In the File tab screen initialise the data relevant to the reporting system. Enter the “Location Of Report Output Files”. This is the default directory where reports printed to file are to be placed. Also enter the “Location Of User-Created Reports”. This is the path to a directory where User-defined report templates are to be stored.
2.11.1.2Reports The reporting interface gives the User complete control over how the reports are formatted and what information is utilised to make up the report. This is facilitated by the use of report templates, which can be edited to suit the specific requirements. It is possible to choose to use the default report templates provided with the system or to choose to create slightly different versions of these reports. The selected templates can then be used to generate the actual reports, which can be sent to a variety of places PROSPER Manual
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(printer, file or screen). The report templates are displayed in a hierarchy and all templates which have been selected (by double-clicking on it) show an X in the checkbox beside the template name. To access the Reports area, select OutputïReports form the menu toolbar. There are two modes for the editing of report templates: System and User. System mode does not allow the User to change any template whereas User mode allows creating new User-defined templates from scratch or based on an already existing system report template and also allows editing an existing User-defined report template. Selecting User mode also makes the User Reports section of the template hierarchy visible. The User Reports hierarchy contains all report templates which have been tagged as being a derivation of a system report template as well as any free standing User-defined templates.
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The reporting main window consists of four main parts: The command segment at the top of the dialogue containing the buttons, the report selection hierarchy, the output device selection group and the template type selection group. The output device group is only used when printing from selected report templates. The available commands are: OK
Print the selected reports to the selected output device and terminate the dialogue
Cancel
Terminate the dialogue
Help
Bring up the on-line help window
Setup
Select a printer
User
Switches between System and User edit mode, This shows or hides the User Reports section of the report hierarchy and enables or disables the Create and Edit buttons. If in User mode this button shows the text ‘System’ and vice-versa.
View
View a previously saved native format file on-screen. This brings up a file selection box for choosing the appropriate report and passes this file name to the Report Executor
Print
Print the selected reports to the selected output device
Create
Create a new user report (only visible in User edit mode)
Edit
Edit an existing user report template or create a new template from a system template (only visible in User edit mode)
Group
Allows the grouping of report templates references and the storing of the group information in a file for later recall. This allows batch printing of reports for any analysis
The available output types are: Printer
Sent the report to the current printer
Screen
The reports are displayed on-screen in a report executor window
Native File
The reports are saved as .FR files in the output reports directory
RTF File
The reports are saved as .RTF files in the output reports directory
Text File
The reports are saved as tab delimited text files for easy spreadsheet import
The native (.FR) file format can only be read by the reporting system whereas the RTF format can be read by many Windows word processing applications. When printing to file the User will be presented with the following dialogue:
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The default directory will be set to the default output directory but this can be altered using the Select Directory button. This can then be applied to all output files by using Change All. If it is necessary to change the output directory of one of the files, this can be achieved by using the Browse button (button that shown on the right side of the filename box) associated with each report. The filenames can themselves be edited in the text box, which contains them. For any given report in the system hierarchy the User can choose to view or print a report using either the system report template provided or a User-defined report template based on that system report template (or at least that position in the hierarchy) or it is possible to choose a report grouping which can be made up from a combination of User and system reports. Choose between these options using the report template type selection group at the bottom right of the main window. If the User report template option for any hierarchy position is selected and there are multiple User-defined report templates for that position, then a dialogue appears which allows selecting the desired template.
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Double clicking on any of the report templates (or selecting and pressing Ok) will cause it to become the User-defined report template for that hierarchy position for the current reports session. The default choice is the topmost user defined report template. It is possible to stop a User-defined report template from being associated with that hierarchy position by selecting it and then pressing Delete. This does not actually delete the report template (it can still be seen within the User Reports section of the hierarchy). If a report grouping is selected, then a similar dialogue appears and the User can select the appropriate group file. After selecting a file all the reports referenced in the group will appear ‘checked’ in the hierarchy and then it is possible to press print for all of these reports to be sent to the selected output device. Template Editor Commands The template editor works on the principle of moveable fields or groups of fields where the inputs to these fields can be any value from PROSPER. Headers and footers can be defined, which can be shown on each page, have fields which have a value which is the result of a calculation or even have groups of fields which are displayed only if a condition is met.
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Data fields from PROSPER are added using the F2 key, selecting the data items required and then pressing Ok when finished. The selected data items will then appear as fields, one by one, as the left mouse button is clicked. The fields can be roughly positioned in this way. The User is not limited to one pass at adding data items to the report template. More items can be added at any time in the same manner. Once a field has been added to the report template the User can edit some of the properties of the text which will be shown in the field and assign a group number to the field by double clicking the left mouse button on it and the font properties can be changed by double clicking the right mouse button on it. Other properties, such as whether the field has a box around it, etc., can be changed through the menu options, a full description of which are given below.
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The template editor commands can be selected by using the menu, toolbar or keyboard shortcuts. Help can be obtained on any menu item by highlighting the menu item and then pressing the F1 key or by consulting the index of help topics under the help menu. File Menu This menu contains commands for saving the current report template file and specifying the report template parameters. Save: Use this selection to save the current report template to the current file name. If a file is not yet specified, the form editor will prompt for a file name. If a file extension is not provided, the editor automatically appends an .FP extension to the report file. If a file with the same name already exists on the disk, the form editor will save the previous file with a backup extension (.RE). Save As: This selection is similar to Save File. In addition, it allows saving the report template to a new file name. PROSPER Manual
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Report Parameters: This option allows setting certain report parameters. Firstly, it allows specifying the name of the report. The margin for the printed page can be set. It is possible to instruct the report executor to print trial records for adjusting forms such as labels and invoices and set the default date format for input. The date format that specified here will be enforced for parameter input during the report execution session, and any date constant used in expressions. Report Filter:
This option allows entering a filter criterion for the report. Each data record will be tested with the expression provided here. A record is selected only if this expression evaluates to a TRUE value. For example, if the expression was sales->amount>100, then only the records with the sales amount more than 100 will be selected. Printer Setup: This option allows selecting a printer from a list of installed printers and invoking a printer specific dialogue box for the selected printer. Select the parameters from a set of printer specific options. These options include page size, page orientation, resolution, etc. The printer options selected here determine the width and height of the report. Exit: Use this function to exit from the form editor session. If the current file is modified, a prompt will ask to save the modifications. Edit Menu: This menu contains commands to edit the report objects. One or more report objects must be selected before using this option. Cut: Use this option to copy the current item or all the items in the current selection to the clipboard. The copied items are deleted from the form. Copy: Use this option to copy the current item or all the items in the current selection to the clipboard. Paste: Use this option to paste the items from the clipboard to the current form. Position Text: Use this option to position the text within the item boundaries. The text can be justified on the left, right, top, or bottom edges or it can be centred horizontally or vertically. This option is valid for the label and field type items only. Item Outlines: © 1990-2011 Petroleum Experts Limited
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Use this option to specify the item boundaries (left, right, top, and bottom) to draw for one or more selected items. The colour and width of the boundary lines can be specified too. Item Background: Use this option to set the background colour or pattern for one or more selected items. Centre Horizontally: This option is used to centre horizontally one or more selected items. When more than one item is selected, the form editor first centres the selection rectangle and then moves the selected items such that the position of the selected items relative to the selection rectangle does not change. Delete Item: Use this option to delete one or more currently selected items. If the current section is being deleted, the program asks for confirmation before the deletion. All items within the section are also deleted. Fonts: Use this function to change the font and colour for the text for one or more selected objects. This option is valid for the field and label type objects only. When selecting this option, the form editor shows the font and colour selection dialogue box. The current font and colours are pre-selected in the dialogue box. Use this dialogue box to specify the selections. Snap to Grid: This option allows turning on or off the invisible grid on the form. When the grid is turned on and an item is moved, it automatically aligns to the closest grid location. This option also allows setting the grid width. Report Size: The following options shrink or elongate the report in the horizontal or vertical direction by the amount equal to the width or the height of the selection rectangle. Expand Horizontally Use this option to create horizontal space by moving items horizontally. For example, consider three items, A, B, and C placed horizontally. If a new item between the items A and B is to be inserted, it is possible to use this function to create the desired space between these two items and place the new item in the newly created space. To move the items B and C toward right, create a selection rectangle after the item A and select this option. The width of the selection rectangle specifies the movement of the items B and C toward right (noted that the selection rectangle does not need to include all items to be moved). All items toward the right of the selection rectangle and with the vertical placement between the vertical spaces spanned by the selection rectangle are moved. Expand Vertically Use this option to create additional vertical space by moving the items downward. For PROSPER Manual
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example, consider three items, A, B, and C placed vertically. If a new item between items A and B is to be inserted, it is possible to use this function to create the desired space between these two items and place the new item in the newly created space. To move items B and C downward, create a selection rectangle below the item A and select this option. The height of the selection rectangle specifies the downward movement of items B and C (noted that the selection rectangle does not need to include all items to be moved). All items below the selection rectangle are moved. This option also expands (vertically) the current section by the height of the selection rectangle. Compress Horizontally Use this option to delete extra horizontal space by moving items horizontally. For example, consider three items, A, B, and C placed horizontally. The User can use this function to bring items B and C closer to the item A. To move items B and C toward left, create a selection rectangle after the item A and select this option. The width of the selection rectangle specifies the movement of items B and C toward left (noted that the selection rectangle does not need to include all items to be moved). All items toward the right of the selection rectangle and with the vertical placement between the vertical spaces spanned by the selection rectangle are moved. Compress Vertically Use this option to delete vertical space by moving the items upward. For example, consider three items, A, B, and C placed vertically. It is possible to use this function to bring items B and C closer to the item A. To move items B and C upward, create a selection rectangle below the item A and select this option. The height of the selection rectangle specifies the upward movement of items B and C (noted that the selection rectangle does not need to include all items to be moved). All items below the selection rectangle are moved. This option also shrinks (vertically) the current section by the height of the selection rectangle. Field Menu: This menu contains options to insert, modify, delete and maintain fields. Insert New Fields: Data Field: This option is used to paste a new data field to the report template. This option will display a list of data files and data fields to choose from. When selecting a field, the form editor displays a positioning rectangle. Use the mouse to position the field rectangle and click any mouse button. The current field attributes can be changed using the Edit Current Field Option. Calculation Field: This option is used to paste a calculation field to the report template. This option will prompt for the name of the field, and the field expression. The field expression can contain any number of valid operators, functions, system fields, dialogue fields, and data fields. The field type is determined by the result of the execution of the field. After entering the field expression, the form editor displays a positioning rectangle. Use © 1990-2011 Petroleum Experts Limited
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the mouse to position the field rectangle and click any mouse button. The current field attributes can be changed using the Edit Current Field Option. System Field: This option is used to paste a system field to the report template. This option will display a list of system fields (date, time, page, etc.) to choose from. When selecting a field, the form editor displays a positioning rectangle. Use the mouse to position the field rectangle and click any mouse button. The current field attributes can be changed using the Edit Current Field Option. Dialogue Field: This option is used to paste a dialogue field to the report template. A dialogue field must have been created using the Edit Dialogue Field Table before using this option. The dialogue fields are used to prompt the User for data during the report execution session. The option will display a list of dialogue fields to choose from. When selecting a field, the form editor displays a positioning rectangle. Use the mouse to position the field rectangle and click any mouse button. The current field attributes can be changed using the Edit Current Field Option. Edit Current Field: This option is used to edit the field attributes for the current field. This option is available only when a 'field' type object is selected. Edit Field Expression: This option is used to edit the field expression for the current calculation field. This option is available only when a 'calculation field' type object is selected (see Insert Calculation Field). The option shows the existing calculation expression and allows making any modifications. Edit Dialogue Field Table: Create: This option is used to create a new dialogue field. Once a dialogue field is created, it can be inserted in the report by using the Insert Dialogue Field selection. A dialogue field is used to prompt the User for data during report execution. For example, it can allow the User to set the begin and end dates for the report. A dialogue field can be used in the field expressions and can be inserted in the report template for information purposes. A dialogue field in the report filter can be used to reject records not meeting a specific User criterion. Modify: This option is used to modify the User prompt, width and prompt order of a dialogue field. The prompt order determines the order at which the dialogue fields are presented to the User for data input. Delete: This option is used to delete a dialogue field from the dialogue field table. The User cannot delete a dialogue field that is being currently used in the report. Section Menu: This menu contains commands to insert, edit and delete report sections. New: This option is used to create a new section. A section is identified by the section banner and the separation line at the bottom of a section. There are three basic types of PROSPER Manual
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sections. A header section displays the data that remain constant or changes only when a sort field changes. The detail section displays the transaction record fields. A footer section is used to display totals and summary information. ReportEase allows up to 9 header and footer sections. A higher numbered header section is allowed only when all the lower numbered headers are already selected. Similarly, a footer section is allowed only when the corresponding header section is already selected. Edit Current: This option is used to modify the properties of the currently selected section. For the 'detail' section, the User can specify the number of records to print across the page. This option can be used to print multiple address labels across the page. Sort Field: This option is used to specify a sort field for a header section. A sort field is used to sort the data records. Break Field: This option is used to specify a break field for a header section. The break field is used to determine a sort break. Typically, the break field would be the same as the sort field. However the break field can be specified differently from the sort field. A calculation expression can also be specified for a break field. Filter: This option is used to enter a filter criterion to print a section. Normally, every section included in the report template is printed in its appropriate sequence. However, if the User wishes to print a section depending upon a condition, he can enter this condition expression using this option. The expression must evaluate to a logical value (TRUE or FALSE). During the report execution, the section will be printed only if the expression evaluates to a TRUE value. Line: This menu contains commands to create and edit a line object: Create a Line: Use this option to draw a line. When selecting this option, the form editor displays a positioning rectangle. Use the mouse to position the rectangle and click any mouse key. The line will be drawn within the position rectangle. The line size can be changed using the sizing tabs. Edit Current Line: Use this option to edit the angle, colour, and thickness of a 'line' type object.
Label: This menu contains commands to create and edit a label object: Create a Label: Use this option to create a new label. When selecting this option, the form editor displays a positioning rectangle. Use the mouse to position the rectangle and click any mouse key. The 'label' object will be created within the positioning rectangle. By default, the form editor inserts the text 'label' in the label item. The label text can be edited in the editing window. Edit Current Label: A label text can be edited by simply selecting the desired label item and clicking on the edit window. As the User inserts or deletes the text, the length of the label text changes. Normally, the © 1990-2011 Petroleum Experts Limited
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form editor will automatically adjust the item box boundaries to completely enclose the new text. However, this automatic size adjustment ceases if the User manually resizes the item boundary by pulling on the sizing tab. This feature can be used to enclose the text in an item box larger than the default size. Picture: This menu contains picture import functions: Import Picture from Clipboard Use this command to copy a picture bitmap from the clipboard. When selecting this option, the form editor creates a positioning rectangle equal to the dimensions of the picture. Use the mouse to position the picture rectangle and click any mouse key. The picture will be placed within the position rectangle. The picture size can be changed using the sizing tabs. Import Picture from Disk File Use this command to read in a picture bitmap from a disk file. When selecting this option, the form editor creates a positioning rectangle equal to the dimensions of the picture. Use the mouse to position the picture rectangle and click any mouse key. The picture will be placed within the position rectangle. The picture size can be changed using the sizing tabs. Arrange: This menu contains commands to align size and space a set of selected objects: Alignment At: Horizontal Top Edge: Use this option to horizontally align the top edge of the selected items to the top edge of the leftmost item in the selection. Horizontal Bottom Edge: Use this option to horizontally align the bottom edge of the selected items to the bottom edge of the leftmost item in the selection. Horizontal Centre Line: Use this option to align the horizontal centre line (imaginary) of the selected items to the centre line of the leftmost item in the selection. Vertical Left Edge: Use this option to vertically align the left edge of the selected items to the left edge of the topmost item in the selection. Vertical Right Edge: Use this option to vertically align the right edge of the selected items to the right edge of the topmost item in the selection. Vertical Centre Line: Use this option to align the vertical centre line (imaginary) of the selected items to the PROSPER Manual
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centre line of the topmost item in the selection. Even Spacing: Horizontally: Use this option to place the selected items horizontally at an equal distance from each other. The inter-item distance is equal to the distance between the first two leftmost items. Vertically: Use this option to place the selected items vertically at an equal distance from each other. The inter-item distance is equal to the distance between the first two topmost items. Even Sizing: Width: Use this option to change the width of the selected items to the width of the topmost item. Height: Use this option to change the height of the selected items to the width of the leftmost item. Undo Previous Arrangement Command: Use this function to undo the previous arrangement command. Report Executor Commands:The report executor allows viewing reports that have been generated and saved to a native format file. It is invoked by using the View option from the reporting main window and selecting a file from the file selection box. The file selection box will point to the default data directory and will have the filter extension set to the correct file type (.FR).
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The options available on this window are: Jump: Print: Preview: Save: Exit:
Go to a particular page in the document. Send the document to the defined printer. Look at the page layout of the document. Save the document to a file (native and RTF). Quit the current window.
2.11.2 Export An export can be made either directly from the individual sections of the program, or from the Output | Export menu option. This section describes how to customise exports.
2.11.2.1Export Setup Use the main menu Output | Export option to export data from a current analysis, or from a previously saved .OUT file. When clicking Export a series of screens leads the User through the process of selecting the data required for the export. To include a section of data, click the check box to the left of a particular item and, depending on the selection, further input screens will be presented. This process ensures that only relevant sections are exported. A sample export dialogue box is shown below:
After entering the choices, Click Done to return to the main export dialogue box. The User must then select a destination for the export data. Clicking Print initiates generation of the data and sends it to the selected destination. Setup accesses a screen for selecting fonts, margins etc. as in the Plot menu (Section 12.1). The font selections made for export data are independent of the plotting fonts. © 1990-2011 Petroleum Experts Limited
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Exported data can be sent to the following locations: ·
Printer - the primary printer as set up under Windows.
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File - Creates an ASCII data file and saves it. Clicking Print displays a dialogue box that requests a file name and destination. Enter a suitable file name ( PROSPER automatically appends a .PRN extension) and click OK to save the file. The Fixed Format option saves a file in a printer ready format that can be imported into a DOS based word processor. Use the Tab Delimited format to save a file suitable for importing directly into a spreadsheet such as EXCEL.
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Clipboard - Clicking Print after selecting this option copies the exported data onto the Windows clipboard. From the Clipboard, the User can view, edit and paste the data directly into another Windows application. e.g. a word processing program.
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Screen Clicking Print after selecting this option allows viewing the exported data on the screen. Scroll through the data using the scrolling thumbs or arrows. When finished viewing, click OK to return to the main menu.
Once a .PRN file has been saved, further copies of the exported data can be made using a word processor from outside PROSPER. To ensure that printed exports are correctly formatted, only non-Proportional fonts can be selected for export data. The fonts on the export setup screen are independent of those selected on the plot setup screen. Ü
PROSPER’s default font selection will give good results on most printers. Choose another font if there are problems printing reports.
Calculation and Export Data LayoutScreen and hardcopy exports can be customised to display only the required variables. For complex calculations, this can save printing large amounts of irrelevant data and detailed reports can still be produced when required. To use the Layout feature, firstly complete a set of calculations. The following example is for PVT calculations. Click the Layout button on the calculation results screen and select the variables to display from the layout screen:
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Show All and Hide All buttons are used to make changes to the entire list of variables. Individual variables can be selected or de-selected by clicking them directly. When clicking OK, only the selected variables will be displayed on the calculation screen. In addition to the calculation results screens, Layout also controls the variables displayed in Output ô Export (to file, clipboard, and printer).
2.11.3 Plot A plot can be made either directly from individual parts of the program, or from the Output | Plot menu option. This section describes how to customise plots for both the screen and hard copy. From the Plot Output main Window select the plot to view by highlighting it in the list of available plots and then press the Plot button or simply double-clicking on the appropriate plot
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Zooming Plots can be zoomed in simply by placing the mouse pointer (which changes to a pair of cross hairs over the active plot area) at the corner of the region to enlarge, and then dragging until the area of interest is enclosed by the zoom box. Release the mouse button and the outlined area will be zoomed to fill the entire plot area. 2.11.3.1Plot Command Summary FinishReturns to the previous menu. Use Finish to close a plot. Scales PROSPER normally picks appropriate scales to display the data. Use Scales to enter
custom upper and lower limits for both X- and Y- scales. To display round numbers on the intermediate grid lines, ensure that the span of the upper and lower plot limits fits evenly with the number of plot blocks set in the Options menu. Replot
Re-plots the graph using the original scales. Use this option to un-zoom a plot. Output PROSPER Manual
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Selects the output options menu. Plots can be output to the Windows clipboard, a Windows metafile or a hard copy device in colour, grey scale or monochrome formats. Plots can then be pasted directly from the clipboard into other Windows applications such as a word processor. Windows metafiles can be saved and read by a variety of applications. If hard copy is selected, the following hard copy options screen will appear:
Select the desired plot options and click Print to output the plot. Depending on the actual hard copy device connected, the User may need to experiment with font styles and sizes. Note that some fonts cannot be rotated, and are unsuitable as a Vertical font. If Yaxis labels are being plotted horizontally, try a different font selection. Return to the plot menu by clicking OK. Colours
This option enables to customise the colour of any item on the plot. Note that laser printers and monochrome monitors will often produce better results if colour plotting is disabled. A sample colour customising screen is shown below:
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Options The Options button enables to customise the overall appearance of the plot screen and select font type and size etc. A sample options screen is shown below:
Some plots include a results box on the screen. If the default position of the box interferes with the plot, it can be moved by holding down the Shift key and using the mouse to drag it to another location. The fonts selected on the Plot options screen apply only to plots. The export data fonts are set up on a separate screen. Variables
Use this button to select variables for plotting. The variables available change according to the type of calculations that have been completed and the particular plot type that has been selected. Where applicable, extended plot variables can be selected. T est Data PROSPER Manual
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Clicking Test data displays a screen in which the User can enter up to 10 measured data pairs. Once the test data has been entered, it can be displayed together with the calculated data when the plot is re-drawn. If the current .OUT file is subsequently saved, the test data will also be saved and will appear on subsequent plots. Help
Accesses the on-line Help system. See Section 14 for more details of the Help system. 2.11.3.2Wellhead Plot Wellhead Plot The Wellhead Plot provides the ability to review wellhead conditions when a surface pipeline system is included in the model. For example, using the wellhead plot option from a System calculation for a file that contains a flowline, it will be possible to view the change in wellhead pressure verses rate and temperature kfkor the given sensitivity variables:
Right-Clicking directly on the plot enables the plot attributes pop-up menu to be access directly.
2.11.3.3System Multi-Variable Plotting System Plot Once the system Multi-Variables (or VLP Multi-Variables) calculation has completed, the results can be plotted in the conventional way by clicking Plot | System Plot. The S ystem plot will appear summarizing all calculations as follows: © 1990-2011 Petroleum Experts Limited
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The difference in features the multi-variable plots offer is that it is possible to change plotting attributes such as: output, scales, Select/Unselect, show/hide VLP and IPR curves, etc., directly from the System (Multi Variables) and VLP (Multi Variables) plot via the Right-Click pop-up menu:
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2.12 Units This chapter describes the system of units. The built in flexibility of the units system enables the User to select any variable and define the unit of measurement to be used. This feature allows to modify the units system so that it corresponds to data reports supplied by a service company or customise the units system to suit the User’s own personal preferences. PROSPER always works internally in Field units. To facilitate data entry and output display in any units system, PROSPER accepts data in the specified Input units and converts it to Oilfield units for calculation. The results (in Field units) are converted back to the specified Output unit set if necessary. By making selections from the different categories, it is possible to work in the preferred units and save the results in the units required by company policy.
The changes made to the units system are retained in the program memory and apply to all files opened during the current processing session. The program allows to create a custom units system.
2.12.1 Units Summary To access the units system, select UnitsïUnits form the menu toolbar. This will display the Units Summary screen:
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The Units Summary screen is contains the list of parameters and their unit’s options: Unit selections Select the units for the input and output of the variables Validation Used to set up the error checking limits for each selected input variable. Click on the Details buttons to the right of each variable name in order to view the details of each particular variable.
2.12.1.1Unit Systems The User can change the unit’s system form tool bar menu
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The following default Units Systems are provided: ·
Oilfield Units
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Norwegian S.I.
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Canadian S.I.
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German S.I.
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French S.I.
· Latin S.I. Customised unit systems can be created and saved under new names. Different units can be selected for both input and output.
2.12.1.2Changing Unit Systems for some variables For each variable, if the mouse points to the unit and right click, the unit system can be changed; this option is available at screen for any input variable.
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2.12.1.3Changing the Units The Input and Output units for each variable on the list can be changed. To change or customise the default Units System: ·
Scroll through the measurement variables list until the unit item to modify is visible on the screen.
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Select the unit category (Input and/or Output) to modify.
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Select the unit field corresponding to the measurement item and click on the arrow to its right to display the list of unit options.
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Select the preferred measurement unit.
To save changes, click Save. A prompt will be displayed to enter a name for the new Units System. This new system can now be recalled and applied to any file. Custom unit sets can be erased by clicking the Delete button, then selecting the unwanted units system. The ability to have separate input and output unit systems allows the User to work with familiar units and to create reports or export data in any required unit system. PROSPER calculates them internally in Oilfield Units. To validate unit conversion factors, click the button located to the right of the particular variable and the multiplier and shift used for unit conversion will be displayed. Clicking Report Print will create a summary report of conversion factors in use. PROSPER Manual
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If some particular units have been modified during the course of a PROSPER session, the changes will be written into the .SIN file when the input data are saved. Irrespective of the current units system settings, recalling a previously saved .SIN file will cause PROSPER to revert to the units saved in the recalled .SIN file. To permanently impose a new set of units on the recalled file, open a custom units file (or use one of the internal unit sets) and then save the .SIN file. The new unit’s settings will be used whenever the . SIN file is loaded.
2.12.1.4Validation Limits To reduce the possibility of entering incorrect data, PROSPER checks that input data falls within predetermined validation limits. For most purposes, the default validation limits are adequate. For particular applications, the User can change the validation limits if required by entering new values directly from the units definition screen. Find the required variable by scrolling through the list, and then enter required changes in the low and high validation limit boxes. Enter the custom validation limits in the units currently in use. To permanently attach the new validation limits to a custom units system, click Save before leaving the validation screen by clicking OK.
2.12.2 Units Details The purpose of the Units Details screen allows adjustment of the precision of data display for both input and output to be adjusted individually for each unit type. To set display precision, select Units Detailed. Scroll though the available units until the required one is shown in the Current box as shown in the following example:
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places to display for each unit type.
2.12.3 Units Reset Use this option to quickly reset the units system back to default values. To specify what Units defaults are please go to the Units Tab in the Preferences screen (File | Preferences).
2.12.4 Units Save To save a customary set of units select Save. After that, a form appear, where the user can decide which units to save (input or output) and enter a new name for the units system.
2.13 Wizard This feature allows the User to set up models and perform certain tasks following a predefined sequence. The use of Wizards is of particular benefit to inexperienced Users, as it allows to easily set up a model based on active wizard examples by advancing through the input screens in the correct sequence and asking at any step the User for the required information. In this way the User will familiarize with PROSPER windows as well as with the essential steps required to set up, match and use the models.
2.13.1 Running the Wizard A few wizard examples are available when installing PROSPER. These examples are step-by-step guides to build typical models, like naturally flowing wells, ESP, etc. In order to run wizard examples follow first of all select Wizard from the main menu PROSPER Manual
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toolbar:
Then select the desired Wizard and click on Run to run it. All that the User has to do is to follow the instructions that time to time are displayed and complete the input screens with the required data.
2.13.2 Creating/Editing a Wizard From the main Wizards window it is possible to access a series of functions that allow the User to create his own wizard or edit an already existing one. To modify an existing wizard select Edit. This will access the wizard script window:
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To create a new wizard select instead New. This will display an empty script window. The script consists of a series of VB commands using OpenServer strings to set the values of the input parameters, perform calculations, and retrieve results. Please refer to the OpenServer User Guides for further details about the basic OpenServer functions. On the top part of the script window there is the Commands list window, which provides immediate access to all the OpenServer variables. This window allows selecting the desired variable and getting a copy of it, which can be pasted in the script window below.
2.13.2.1Notes of OS strings A class of OpenServer strings - the so-called menu commands - allow displaying each of the input screens. The structure of these commands is in general: PROSPER Manual
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DoCmd(“PROSPER.MENU.
”) If is for example Options, the command will display the main PROSPER options. To display a plot, instead, the command is: DoCmd(“PROSPER.PLOT.”) If is 1, for example, the command will display the IPR plot.
2.13.2.2Wizard examples As above mentioned, a few Wizards are available along with the software. These examples lead step-by-step the User through the screens in order to build typical models. The example scripts can also be used by experienced Users as templates to build their own scripts. Recommendation Petroleum Experts recommends to set up the models according to the worked examples shown in the Examples Guide. This will allow the User to have a better understanding of the physics that is behind the software and the importance of the matching process.
2.14 Help PROSPER has an on-line Help facility which enables the User to get information quickly
about a menu option, input field or function command. This facility enables to display instructions for completing a particular task or input field without exiting from the current screen. The help windows offer a list of topics which not only include definitions and functions specific to PROSPER, but details on using some features of Windows as well. To use the PROSPER on-line help system, the help file must be located in the same directory as the program. If the User is new to Windows, information on using the Help system can be made available when selecting the Help option in the PROSPER main menu and choosing 'Using Help'. This will display a help screen from which the information required can be selected from a list of topics. The Help facility has function buttons located at the top of the windows, which can be used to navigate within the help system. If a particular feature is not currently available, the button associated with that function is dimmed. Information on specific help topics may lead to other related topics. Some words in the Help windows are marked with a solid underline and appear in colour (green) if the User uses a colour screen. These words are called jump terms and can be used to move around Help more quickly. © 1990-2011 Petroleum Experts Limited
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When clicking a jump term, Help will move directly to the topic associated with the underlined word(s).
2.14.1 Finding Information in Help
2.14.1.1Use the Search feature in Help This facility is useful for finding specific information about using the keyboard. For example, the keys used for text selection. Type in the phrase "text selection" and search the system for the phrase or select the topic from the list displayed.
2.14.1.2Use the Help Index This option is useful for viewing specific sections listed in the Help index. Go to the topic or command of interest and select the item required. 2.14.1.3Context Sensitive Help This feature can be used while working to give information about a particular menu option.
2.14.2 Accessing Help To get information quickly about a specific menu option or entry field in PROSPER, the following methods will display the help facility: 2.14.2.1Help Through the Menu From the menu bar in PROSPER, click on Help (or ALT H) and select Index. From the list of help topics, select the topics to see by pointing to the specific item.
2.14.2.2Getting Help Using the Mouse · Press SHIFT+F1 The pointer will change to a question mark. · Choose the menu command or option. or · Click the Menu command or option, and holding the mouse button down press F1.
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2.14.2.3Getting Help Using the Keyboard Press the ALT key plus the first letter of the menu name, option and press F1.
2.14.2.4To Minimise Help If using the mouse, click the minimise button in the upper-right corner of the help window. If using the keyboard, press ALT SPACEBAR N. This procedure will close the help window, but keep the help icon on the Windows desktop.
2.14.3 Flow Correlations Click Help / Flow Correlations to access a detailed generalized discussion about the history and reasons behind flow correlations and issues that relate to their use in PROSPER.
2.14.4 Open Server Click Help/Open Server to access the complete lists of OpenServer variables, commands and functions.
2.14.5 Help About PROSPER Click Help About PROSPER and the following screen will be displayed:
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If the User need to contact Petroleum Experts about a problem with the program, please have the version number and creation date shown on this screen available should it be required.
2.14.6 Web Options From the Help menu it is possible to access to the following on-line services: · Web Home Page. This option accesses the Petroleum Experts website www. petroleumexperts.com · Web User Area. This options accesses a dedicated area of the Petroleum Experts website containing technical information about the IPM Suite and news about the new developments · Technical Support. This option accesses the section of the Petroleum Experts website on which it is possible to post technical support requests to the Petroleum Experts Technical Support Service
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2.15 Appendix 2.15.1 A - References 2.15.1.1PVT Calculations 1 Sutton, R.P. & 'Evaluation of Empirically Derived PVT Properties SPE Reservoir Engineering, Farshad, F.F. for Gulf of Mexico,' (Used for Glaso, Lasater, (Feb. 1990), 79-86. Standing & Vazquez-Beggs) 2 Beal, C.
'The Viscosity of Air, Water, Natural Gas, Crude Trans., AIME (1946) 165, 94Oil and its Associated Gases at Oil Field 98. Temperatures and Pressures,'
3 Beggs, H.D. & 'Estimating the Viscosity of Crude Oil Systems,' Robinson, J. R.
JPT (Sept. 1975), 1140-1144.
4 Carr, N.L., et 'Viscosity of Hydrocarbon Gases Under Pressure,' al
Trans., AIME (1954), 264-268.
5 Eilerts et al
Monograph 10, U.S. Bureau of Mines, Washington D.C. (1957).
'Phase Relations of Gas Condensate Fluids,'
6 Brinkman, F. 'Equilibrium Ratios for Reservoir Studies', H. & Sicking, J.N.
SPE (Nov. 1959), SPE reprint series No. 15, 240-246.
7 Katz, D. Kurata, F.
Ind. Eng. Chem. (June, 1940) 32, No. 6, 817-827.
& 'Retrograde Condensation',
8 Katz, D., 'Surface Tension Monroe, R. & Dissolved Gases,' Trainer, R.
of
Crude
Oils
Containing Trans., AIME (1943), 1624, 285-294.
9 Lee, et al
'The Viscosity of Natural Gases'
Trans., AIME (1966), 1002.
997-
1 Lohrenz et al 0
'Calculating Viscosities of Reservoir Fluids From JPT (Oct. 1964), 1171-1176. Their Compositions'
1 Coats, K.H. 1
'An Equation of State Compositional Model'
SPE 8284 SPE ATCE, Las Vegas, Nevada, Sept. 23-26, 1979.
1 Nghiem, L.X., 'Compositional Modelling with an Equation of State' SPE 9306 SPE ATCE, 2 Fong, D.K. & Dallas, Texas, Sept. 21-24, Aziz, K. 1980. 1 Winkler, H.W. 'Algorithm for More Accurately Predicting Nitrogen- SPE 18871 SPE POS, 3 & Eads, P.T. Charged Gas-Lift Valve Operation at High Ok lahoma City, March 13-14, Pressures and Temperatures' 1988. 1 Peng, D.-Y. 'A New Two-Constant Equation of State' 4 and Robinson, D.
I.&E.C. Fundamentals (1976) 15, No.1, 59-64.
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B. 1 Bradley et al 5
'Effect Of Pressure On The Viscosity Of Water'
Petroleum Engineering Handbook . SPE 1987
1 Bukacek, 6 Richard F.
'Equilibrium Moisture Content Of Natural Gases'
Research Bulletin Vol 8, Institute of Gas Technology, Chicago USA, 1955.
1 Muhammad "PVT Correlations for Middle East Crude Oils" 7 All AlMarhoun
JPT (May 1988), 650-666
1 E. O. "An Improved Temperature-Viscosity Correlation Journal of Petroleum Science 8 Egbogah & J. For Crude Oil Systems" and Engineering, 5, (1990), T. Ng 197-200
2.15.1.1.1 CO2 Injection The best approach to model CO2 Injection is to use an Equation Of State PVT Model and set the Fluid Type as "Retrograde Condensate" and not "Dry And Wet Gas". The reason behind this is that the "Dry And Wet Gas" models considers the fluid as a single phase throughout the entire system and modifies the gas properties to account for the condensate. The "Retrograde Condensate" model assumes multiphase flow modelling allowing for gas and/or liquid phases to be present anywhere in the system (depending on the prevailing pressure and temperature). N.B. In CO2 Injection, depending on the conditions of pressure and temperature, it is possible to have phase changes somewhere in the system (Gas-.Liquid->Gas) The Gray (and Modified Gray) correlation uses its own internal PVT calculator that overrides the Prosper-calculated pvt properties and therefore this should not be used to model CO2 Injection. 2.15.1.1.2 PVT Separator Pressure The dry-wet gas model in PROSPER assumes that the condensate drops out at the separator assuming single phase (gas) in the tubing. (Besides any possible water produced which will give two-phase flow). The objective is to obtain the properties of the Well stream gas from the separated gas, tank vented gas and condensate. (Please see next diagram).
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The ideal way to do this is to perform a compositional analysis where the composition of the gas separated, condensate and the gas vented are known. Then these fluids are recombined to get the well stream composition and properties. However most of time the compositions are unknown, and also the quantity and gas specific gravity of the stock tank gas vented are often not measured. In those cases, correlations can be used to calculate the gas specific gravity and the GE (Gas equivalent) or VEQ (volume equivalent). The VEQ or GE represents the volume of gas vented in the tank plus the volume in scf that would be occupied by a barrel of stock-tank liquid if it were gas. PROSPER is using a correlation that depends on the separator pressure to calculate the GE. The GE is added to the gas rate and used to calculate the pressure losses in the tubing using the energy balance equation. In fact from the diagram above we can see the separator pressure dependency, for instance if the separator pressure is 0 psig, the tank vented gas will be zero, if the separator pressure is higher then more gas will pass in solution with the liquid towards the tank. So the separator pressure has an impact on GE. © 1990-2011 Petroleum Experts Limited
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Other correlations of GE available in the literature that depends on the separator pressure can be found in the following references: “An Improved method for the determination of the Reservoir gas specific gravity for retrograde gases” Gold et.al., also the in the book “The properties of Petroleum Fluids” W. McCain (Chapter 7: Properties of Wet Gases) explains and show some these correlations available. 2.15.1.2IPR Calculations 1 Dietz
'Determination of Average Trans., AIME.(1965). Reservoir Pressure From Build Up Surveys,'
2 Fetkovich M.J.
'The Isochronal Testing of Oil SPE 4529 SPE ATCE, Wells,' Las Vegas, Sept. 30Oct. 3.
3 Forcheimer et al
Zeits V. Dutching, (1901), 45, 1782-1786.
4 Goode P.A. & 'Inflow Performance of Horizontal SPE 21460 Reservoir Kuchuk F.J. Wells,' Engineering (Aug. 1991) 6, No. 3, 319-323. 5 Jones L.G., 'Use of Short Term Multiple Rate SPE 6133 SPE ATCE, Blount, E.M. et Flow Tests to Predict New Orleans, Oct. 3-6. al Performance of Wells Having Turbulence,' 6 Vogel J.V.
'Inflow Performance Relationships JPT (Jan. 1968), 83-92. for Solution Gas Drive Wells,'
7 Houzé, O.P., 'Infinite Conductivity Vertical SPE 12778 SPE Horne, R. & Fracture in a Reservoir with Regional Meeting, Long Ramey, H.J. Jr. Double Porosity Behaviour' Beach, California, April 11-13, 1984. 8 Karakas, M. & 'Semi-Analytical Tariq, S. Models for Completion'
Productivity SPE 18271 SPE ATCE Perforated , Houston, Texas, Oct. 25, 1988.
9 Dikken, B.J.
'Pressure Drop in Horizontal Journal of Petroleum Wells and its Effect on Their Technology, November, Production Performance' 1990; Trans., AIME, 289.
1 Chaperon, I. 0
'Theoretical Study of Coning SPE 15377 SPE ATCE Towards Horizontal and Vertical , New Orleans, Oct. 5-8. Wells in Anisotropic Formations'
1 Goode, P.A. & 'Inflow Performance of Partially SPE 19341 1989 SPE PROSPER Manual
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1 Wilkinson, D.J. Open Horizontal Wells'
568
Eastern Region Meeting, Morgantown, WV, Oct. 24-27. Also JPT, August 1991, pp 983-985.
1 Papazatacos, 'Cone Breakthrough Time 2 P., Herring, T. Horizontal Wells' R., Martinsen, R. & Skjaeveland, S. M.
for SPE 19822 SPE ATCE , San Antonio, Texas, Oct. 8-11.
1 Cinco-Ley, H., 'Transient Pressure Behaviour SPE 6014 SPE ATCE, 3 Samanieogo, For a Well With a Finite- New Orleans, Louisiana, F. & Conductivity vertical Fracture ' Oct 3-6 1976 Dominguez, N. 1 Mavor, M.J. & 'Transient Pressure Behaviour of SPE 7977 California 4 Cinco Ley, H Naturally Fractured Reservoirs' Regional Meeting SPE, Ventura, California, April 1979 1 Wong, D., 'Application of the Pressure SPE 13056 SPE ATCE 5 Harrington, A. Derivative Function in th Pressure , Houston, Texas, Sept. & Cinco Ley, H Transient testing of Fractured 16-19, 1984 Wells' 1 Warren, J.E. & 'The behaviour of 6 Root, P.J. Fractured Reservoirs' 1 Hegre, T.T. & 'Productivity of 7 Larsen, L. Horizontal Wells'
Naturally SPE 426, SPEJ (Spet 1963), 245-255
Multifractured SPE 28845 SPE European Petroleum Conference, London, UK, October 1994
1 Urbanczyk, C. 'Optimization of Well Rates under SPE Advanced 8 H, Gas Coning Conditions.' Technology Series, Vol. & 2, No. 2, April 1994. Wattenbarger, R.A 1 Larsen, L. 9
'Productivity Evaluations of Wells in Long Rectangular Drainage Areas.' H. Cinco, F. G. 'Unsteady-State Pressure SPE 5131 Miller, H. J. Distribution Created by A 2 Ramey, Jr. Directionally Drilled Well' 0
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2.15.1.3Multiphase Flow Calculations 1.
Anand, et al, ‘Predicting Thermal Conductivities of Formations from Other Known Properties,’ JPT (Oct. 1980).
2.
Ashford, F.E, and Pierce, P.E.: ‘The Determination of Multiphase Pressure Drops and Flow Capacities in Downhole Safety Valves (Storm Chokes)’, paper SPE 5161 presented at the 1974 SPE Annual Fall Meeting, Houston Oct. 6-9.
3.
Beggs, H.D. and Brill, J.P.: ‘A Study of Two Phase Flow in Inclined Pipe,’ JPT (May 1973), 606-617.
4.
Churchill-Chu, ‘Correlating Equations for Laminar and Turbulent Free Convection from a Horizontal Cylinder,’ International Journal Heat Mass Transfer (1975) 18, 1049-1053.
5.
Fancher, and Brown, G.G.: ‘Prediction of Pressure Gradients for Multiphase Flow in Tubing,’ SPE Journal (Mar. 1963), 59-64.
6.
Fortunati, ‘Two Phase Flow Through Well-head Chokes,’ paper SPE 3742 presented at 1972 SPE European Spring Meeting, Amsterdam, May 17-18.
7.
Hagedorn, A.R. and Brown, K.E.: ‘Experimental Study of Pressure Gradients Occurring During Continuous Two-Phase Flow in Small-Diameter Vertical Conduits,’ JPT (Apr. 1965), 475-484.
8.
Mandhane et al, ‘A Flow Pattern Map for Gas-liquid Flow in Horizontal Pipes,’ International Journal Multiphase Flow, 1, 537-541.
9.
Moody, ‘Friction Factor for Pipe Flow,’ Trans., AIME (1944), 66, 671-675.
10.
Mukherjee, H. and Brill, J.P.: ‘Liquid Holdup Correlations for Inclined TwoPhase Flow,’ JPT (May 1983), 1003-1008.
11.
Oranje, ‘Condensate Behaviour in Gas Pipeline is Predictable,’ Oil and Gas Journal (July 1973), 39-43.
12.
Orkiszewski, ‘Predicting Two Phase Pressure Drop in Vertical Pipes,’ JPT (June 1967), 829-833.
13.
Duns, H. Jr and Ros, N.C.J.: ‘Vertical Flow of Gas and Liquid Mixtures in Wells,’ Proc., Sixth World Petroleum Congress, Frankfurt (1963) 451.
14.
Tansev, E. Startzman, R.A. and Cooper, A.M.: ‘Predicting Pressure Loss and Heat Transfer in Geothermal Wellbores,’ paper SPE 5584 presented at the 1975 SPE Annual Fall Meeting, Dallas, Sept. 28-Oct. 1.
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15.
570
Gould, T.L, Tek, M.R. and Katz, D.L.: ‘Two-Phase Flow Through Vertical, Inclined, or Curved Pipe,’ JPT, August, 1974, 915-925.
2.15.1.4Temperature Calculations 1Chiu, K. 'Modeling of Wellbore Heat Losses SPE 22870 1991 SPE Annual in Directional Wells Under Fall Meeting, Dallas, Oct. 9-9. and Changing Injection Conditions,' pp 517 - 528. Thakur, S. C. 2Hasan, A.R. 'Heat Transfer During Two-Phase SPE 22866 1991 SPE Annual and Kabir, Flow in Wellbores: Part I - Fall Meeting, Dallas, Oct. 9-9. Formation Temperature,' pp 469 - 478. C.S. 3Hasan, A.R. 'Heat Transfer During Two-Phase SPE 22948 1991 SPE Annual and Kabir, Flow in Wellbores: Part II - Wellbore Fall Meeting, Dallas, Oct. 9-9. Fluid Temperature,' pp 695 - 708. C.S. 4Carslaw, H. 'Conduction of Heat in Solids,' S. and Jaeger, J.C.
Oxford Science Publications, Oxford, U.K., 1959.
2.15.1.5Artificial Lift Design 1Gibbs S.G.
'Predicting the Behavior of SPE 588 SPE Rocky Mountain Regional Sucker-Rod Pumping Meeting, May 27-28, 1963, in Denver, Systems' Colorado, 769-788.
2Schmid 'System Analysis for Sucker- SPE 15426 SPE ATCE, October 5-8, t Z., Rod Pumping' 1986, in New Orleans, Louisiana, 125Doty D. 130. R. 3Gibbs 'Computer Diagnosis of SPE 1165 SPE Annual Fall Meeting, Down-Hole Conditions in October 3-6, 1965, in Denver, Colorado, S.G., Neely A. Sucker Rod Pumping Wells' 91-98. B. 4Patton L.D.
'A Computer Technique for SPE 1986 SPE 38th California Regional Analyzing Pumping Well Meeting, October 26-27, 1967, in Los Performance' Angeles, California, 243-249.
5Jenning 'Design of Sucker-Rod Pump SPE 20152 Petroleum Technology in the Systems' s J.W. Second Century, October 16-19, 1989, in Socorro, New Mexico, 77-87.
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6Gibbs S.G.
'A Review of Methods for SPE 9980, December 1982, 2931-2942. Design and Analysis of Rod Pumping Installations'
7Gabor Takacs
'Gas Lift Manual"
8Gabor Takacs
'Sucker-Rod Manual'
Penn Well Corporation Tulsa, Oklahoma 2005 Pumping Penn Well Corporation Tulsa, Oklahoma 2003
2.15.2 B - Equations 2.15.2.1Black Oil Model for Condensate
PSEP TSEP TANK
ggtot
g gsep GOR
sep
g gtnk GOR
tnk
Total GOR is the total of separator and tank GOR.
Rtot = Rsep + Rtnk Feed gas gravity ( g gtot ) is the weighted average of separator and tank gas gravities.
g g tot =
(g g sep Rsep + g g tnk Rtnk ) Rtot
2.15.2.1.1 Mass Balance Calculations Based on the principles of mass balance the following equations can be derived. Known Parameters:
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Produced Gas Gravity
ggt
Condensate specific gravity
γc CGR 28.966 62.43 0.0764 Mc
The condensate to gas ratio Air Mol. Wt. Water density Air density @ SC Mol.wt of condensate
572
STB/SCF lb/lb.mol lb/cu.ft lb/Scf lb/lb.mol
Basis of calculations : 1 SCF of Produced gas. The gas gravity of the mixture g can be evaluated using the following equation
Total inlet mass calculation: Mass of Produced gas = =
Vol of gas @SC x Density of gas @SC Vol of gas @SC x Gas gravity x Density of air @SC
=
= Mass of Condensate = =
Vol of Cond @SC x Density of Cond. @SC Vol of Cond.@SC x sp.gravity x Density of water @SC
=
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=
Thus, Total mixture mass = Mass of Produced gas + Mass of Condensate
Total inlet moles calculation: Moles of Produced gas = =
Mass of gas/ Mol.Wt.of gas Mass of gas / Gas gravity x Mol.Wt. air
=
= Moles of Cond.
=
Mass of Cond./ Mol.Wt.of Cond
=
= Thus, total mixture moles = Moles of Produced gas + Moles of Condensate PROSPER Manual
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Thus the gas gravity of the inlet mixture is
This expression thus gives, the average gas gravity of a mixture, which has a condensate to gas ratio of CGR STB/SCF, with the gas having a gas gravity of ggt and the condensate having a specific gravity of γc and molecular weight of Mc. This also can be used to work out the condensate to gas ratio of a mixture gas if the gas gravity is known as shown in the following equation.
2.15.2.1.2 Using the mass balance results to define Condensate Model Based on this formulation, the separator gas gravity and the average total gas gravity, the effective CGR vaporised in separator gas is estimated as follows
CGR sep =
g g sep - g g tot 4588 .3 g c - 132904 g g sep g c /M c
Separator liquid/gas ratio (
) referred to separator liquid.
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Also assuming that the condensate is above dew point, the initial CGR under reservoir conditions is,
CGR res =
Rsep
1 + Rtnk
Thus, the gas gravity under reservoir conditions can be found as
g g res =
g g tot + 4588 .3 g c CGR res 1 + 132904 g c CGR res / M c
Thus, we can have two independent equations, which are · At Reservoir conditions:
g g res = ·
g g t + 4588 g csc CGR res 1 + 132904 g csc CGR res / M c
At Separator Conditions:
CGR
sep
=
g g sep - g g tot 4588 .3 g csc - 132904 g g sep g csc /M c
NOTE: ggt > ggsep
CGRsep negative
At and above Dew Point:
CGR res
=
Rsep
1 + Rtnk
The CGR at pressures lower than dew point is estimated by a second degree polynomial as shown
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CGR = CGR
min
+ (CGR
res
æ P f ö÷ - CGR min )ç çP 1 - f ÷ø è dewpoint
576
2
where Pmin being the maximum liquid dropout pressure and a function of the dewpoint pressure. i.e. Pmin = F (Pdewpoint
)
Pdew is an input to the model. The vaporised CGR curve as a function of pressure looks as below:
comp
f P Pdew
1
f is from maximum liquid dropout or mix condensate in solution. CGR = CGR min + (CGR res - CGR min )
P æ ö - f ÷ ç ç Pdewpo int ÷ ç ÷ 1- f çç ÷÷ è ø
*
2
2.15.2.1.3 Estimation of CGRmin First calculate condensate mole fraction:
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f = 0.15 +
7.08 + 1.45 * % Condensate TRES - 161
CGR min = CGR res - Lmax
(From Eilerts et al)
Bg 561 .5 Bo
Where Lmax is the maximum liquid dropout percentage. Thus we need to estimate Bo and Bg to find CGRmin from the following equation
CGR min
=
CGR
res
- Lmax B g
561 .5 Bo
2.15.2.2Multiphase Pseudo Pressure
æk ¶P ö ÷÷ q o = 2prh çç o * m ¶ r è o ø æ k g ¶P ö ÷ q g = 2prh ç * çm ÷ ¶ r è g ø æk ¶P ö ÷÷ q w = 2prh çç w * m ¶ r è w ø Total Mass Flow Rate: PROSPER Manual
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æ kg k k m r = 2prh ç r o o + r g + rw w ç mo mg mw è
578
ö ¶P ÷ ÷ ¶r ø
Change of Mass Flow Rate Across Annulus:
¶m r ¶ = 2ph ¶r ¶r
ì kg ko k ï æç + rg + rw w ír ç r o mo mg mw ï î è
ö ¶P ü ï ÷ ÷ ¶r ý ï ø þ ......................1
Change in Mass Flow Rate = Change in Density / Mass accumulation in Annulus
¶m r ¶r = 2prh f ¶r ¶t
..............................................................2
r = So ro + S g r g + S w r w
1 and 2 ð 3
¶ ¶r
ì kg ko k ï æç + rg + rw w ír ç r o mo mg mw ï î è
ö ¶P ü ¶r ï ÷ = rf ý ÷ ¶r ï ¶t ø þ .....................
By Definition:
Equation 3 becomes:
¶ ¶r
_ ì rg ro r w ö÷ ¶P ü ¶P ï æç ï + kg + kw = rf r c ír ç k o ý mo mg m w ÷ø ¶r ï ¶t ï î è þ
To Linearise this Equation:
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p
æ ö r ç r o k o + k g g + k w r w ÷¶P ò0 ç m o mg m w ÷ø è p ö k g mo k æ k m = ò o ç ro + r g + w o r w ÷¶P ÷ m o çè ko m g ko m w 0 ø p qg ö k æ q = ò o çç r o + r g + w r w ÷÷¶P mo è qo qo ø 0 p GOR out B g ö k æ WOR out Bw = ò o çç r o + rg + r w ÷÷¶P mo è Bo Bo ø 0
m( p ) =
Combining we get:
¶ æ ¶m( p ) ö rf r c m o ¶m( p ) * ç r ko ÷= ¶r è ¶r ø F ¶t Where
F = ro +
GOR out Bg Bo
rg +
WOR out Bw rw Bo
_ m o ¶m( p ) ¶ 2 m( p ) 1 ¶m( p ) + = f c 2 r ¶r Bo ¶t ¶r ð
ð
C = c
So ro + S g r g + S w r w F
For Condensates:
m g ¶m( p ) ¶ 2 m( p ) 1 ¶m( p ) + = fc 2 r ¶r kg ¶t ¶r C=c
Fg =
So ro + S g rg + S w r w Fg
Bo CGR out B WGR ro + r g + w rw Bg Bg
2.15.2.3Temperature Models
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2.15.2.3.1 Rough Approximation Temperature Model
The ambient temperature at point x is:
which implies that the rate of change of temperature with depth
The fluid temperature at point x is then found from
Where: Ta1 = Ambient temperature at L1 T1 = Fluid temperature at entry
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T(x)= Fluid temperature at current location q
= Deviation angle = Fluid mass flow rate
Cp = Specific heat capacity U
= Overall heat transfer coefficient referred to pipe inside diameter
D
= Pipe inside diameter
G = Geothermal gradient W = Product of phase mass flow rates and heat capacities +
g
Cpo +
o
Cpw
w
Cpg
2.15.2.3.1.1 Overall Heat Transfer Coefficient
This value is used to calculate heat loss in surface or downhole pipe work This should not be confused with the thermal conductivity for a particular type of pipe. The overall heat transfer coefficient accounts for the heat flow through the pipe, annulus (in a well) and insulation (if present) to the surroundings. Heat transfer by forced and free convection, conduction and radiation must all be accounted for in the value of the overall heat transfer coefficient. Insulated buried flowlines can have heat transfer coefficients as low as 0.1 (BTU/hr/ft2/0F) whereas uninsulated, unburied flowlines can be higher than 100. Typical values for individual flowlines are :Buried Carbon Steel Flowlines 1.0 Unburied Carbon Steel Flowlines
16.0
Carbon Steel Risers in Water
18.0
Carbon Steel Risers in Air
5.6
Flexible Pipe in Water
2.8
The overall heat transfer coefficient (U value) used to determine the heat exchange in the Surface Equipment (Xmas Tree to Manifold) is entered in the Surface Equipment section of the Equipment Data input area. The overall heat transfer coefficient entered in the Geothermal Gradient section is the one used to determine the heat exchange in the Downhole Equipment (Xmas Tree downward).
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The U values entered in the two sections mentioned above will be used throughout the model when running a calculation like System, Gradient, VLP calculation, or also the VLP matching itself. During the VLP/IPR matching process the U value can be tuned in order to match the observed temperature profile (using the feature Estimate U value in the VLP/IPR matching screen). As “rule of thumb” we suggest to use as starting values of U the following: - In the case of dry gas fluid: 1-3 BTU/(hr×ft2×0F) - In the case of retrograde condensate fluid: 5-7 BTU/(hr×ft2×0F) - In the case of oil fluid: 8-9 BTU/(hr×ft2×0F) The values of the heat transfer coefficient above reported are the ones that we suggest to use as starting point during the temperature matching process, as we found out that in many cases they are not too far from the actual values. Please, note that the heat transfer coefficient, which accounts at the same time for the different mechanisms of heat transfer, may have very different values, depending on all the factors affecting the heat transfer (the packer fluid, fluid characteristics, flow regime, type of completion, materials used, thickness of tubing and casing etc.). Again, if a measurement of wellhead temperature is available along with the well test, it is possible to get the correct estimation of the U value.The overall heat transfer coefficient is referenced to the pipe inside diameter 2.15.2.3.2 Enthalpy Balance Enthalpy Balance temperature model in PROSPER applies the general energy equation for flowing fluid:
In terms of Enthalpy , this is written:
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In other terms:
If heat transfer with the surroundings (Q) is neglected, the usual pressure equation solved in multiphase flow results. PROSPER solves the general energy equation by considering the enthalpy balance across an incremental length of pipe. The enthalpy term includes the effects of pressure (including Joule-Thomson effect) and phase changes. The algorithm commences by calculating the enthalpy at the known pressure and temperature of the first calculation node. i.e. H1 at (T1,P1) For a given pipe increment, the enthalpy (H2) at the other end of the pipe is estimated. The difference (H2-H1) is compared to DH.
Where
If previous calculations exist, then:
P2 = P1 - GDL ;
T2 = T1 -
dt DL dz
to give the first estimate of H2 We now deal with a piece of tubing of pipe length L, and P=
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;
T=
T1 + T2 2
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The total heat transfer coefficient is estimated for the T, P of the iteration step to calculate the heat exchanged. Using the energy equation, we can find dh. If dh does not equal H2-H1, the iteration continues until convergence. The Enthalpy Balance method solves the energy equation simultaneously for both temperature and pressure. The solution temperature at the downstream side of the pipe increment is therefore the value of T2 when the iteration has converged. The heat transfer coefficient is used to calculate dQ within the enthalpy balance iterations and not the temperature. The heat transfer coefficient is itself a function of the temperature of both the fluid and the surroundings; therefore iteration is required to find both the heat transfer coefficient and the enthalpy balance. The formation is a thermal sink at temperature Te. The temperature profile near the wellbore is dependent upon producing time and the thermal diffusivity of the formation. The heat diffusivity equation accounts for localised heating (or cooling) of the formation by the well fluids. For a pipe increment, the heat flow is calculated using:
Where: infinity.
is the temperature difference between the fluid and the formation at
is the effective thermal conductivity of the formation (including allowance for well fluids in porous formations) is the solution of the heat diffusivity equation The exact solution of heat diffusivity equation is:
(Carslaw and Jaeger Page 336) This integral poses numerical problems as u0 and is slow. This equation is evaluated for very early times only. For intermediate times, PROSPER uses a fit of the TD vs tD generated using the exact solution. At later times a logarithmic approximation is used: © 1990-2011 Petroleum Experts Limited
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Where thermal diffusivity This formulation approximates the exact solution with less than 1% error. (From KwanChu and Subash Thakur). is the overall heat transfer coefficient.
The overall heat transfer coefficient takes into account forced convection inside the pipe and free convection outside the pipe plus radiation and conduction.
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Heat transfer from the pipe is in three terms: ·
Conduction
·
Forced Convection
·
Free Convection and Radiation
Now, let us examine the components of the overall heat loss coefficient individually: is due to forced convection inside the pipe
Where k is the average conductivity.
= mixture Reynolds number (depends on VLP correlation used) i.e. mixture Prandtl number
In the annulus, the free convection term is:
where: and
i.e. mixture Grashof number mixture density
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thermal expansion coefficient The convection terms are themselves a function of temperature. Iteration is therefore required to find the annulus temperature for the convection term and determine the overall heat transfer coefficient H2
H1
rti
H1
P1 , T1
rto rci rco rcem
The radiation term is given by:
where
is the Stefan-Boltzman constant and
is emissivity.
The Conduction Terms can be expressed as (considering the tubing), where:
h = heat transfer coefficient in W / (K m2) k = effective thermal conductivity in W / (m K)
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Similar expressions are used for each casing string and each term combined to find the total conductivity term .
2.15.2.3.2.1 Default Thermal Properties Database
The data listed below is at standard conditions. Correlations are used to estimate thermal properties at other temperatures and pressures. Dry Rock Properties Specific Gravity
Cp
Conductivity
BTU/lb/ deg F
BTU/hr/ft/deg F
Sandstone
0.183
1.06
2.64
Shale
0.224
0.7
2.4
Limestone
0.202
0.54
2.71
Dolomite
0.219
1.0
2.87
Halite
0.219
2.8
2.17
Anhydrite
0.265
0.75
2.96
Gypsum
0.259
0.75
2.32
Lignite
0.3
2.0
1.5
Volcanics
0.2
1.6
2.65
Rock In Situ Fluids Cp
Conductivity
BTU/lb/deg F
BTU/hr/ft/deg F
Water (Low salinity)
1.0
0.35
Water (High Salinity)
1.02
0.345
Heavy Oil
1.04
0.34
Medium Oil
0.49
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Light Oil
0.5
0.0815
Gas
0.26
0.0215
The dry rock properties are modified to wet rock properties using the in-situ porosity, permeability and rock consistency. Downhole Equipment Conduction Heat Transfer Coefficient
Emmissivity
BTU/ft/hr/deg F Mild Steel Tubing
26
0.65
Plactic Coated Tubing
20
0.65
Stainless Steel (13% )
18
0.4
Stainless Steel (15% )
15
0.3
Line Pipe
27
0.9
Plactic Coated Pipe
20
0.9
Flexible
0.3
0.95
Bitumen
0.6
0.95
0.02
0.8
0.1
0.9
Foam Concrete 2.15.2.4Choke Calculation
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From Bernoulli: From Mass Conservation: In the throat, the maximum velocity is the speed of sound. Under critical conditions, the choke becomes independant of the downstream pressure and temperature.
Vms : 2 phase sound velocity from FORTUNATI, Vms will be much lower than the velocity of either phase. Critical conditions are reached at much lower velocities.
For a mono phase
2.15.2.5Multi-Phase Flow Correlations See Also MultiPhase Flow References The flowing pressure gradient in a producing well comprises 3 terms: Gravity
due to density of the produced fluid mixture
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Friction
from shear stress between the flowing fluids and the pipe wall
Acceleration
as a result of expansion of fluids as the pressure reduces
For oil wells, the main component of pressure loss is the gravity or hydrostatic term. Calculation of the hydrostatic pressure loss requires knowledge of the proportion of the pipe occupied by liquid (holdup) and the densities of the liquid and gas phases. Accurate modeling of fluid PVT properties is essential to obtain in-situ gas/liquid proportions, phase densities and viscosities. Calculation of holdup is complicated by the phenomenon of gas/liquid slip. Gas, being less dense than liquid flows with a greater vertical velocity than liquid. The difference in velocity between the gas and liquid is termed the slip velocity. The effect of slip is to increase the mixture density and hence the gravity pressure gradient. Multi-phase flow correlations are used to predict the liquid holdup and frictional pressure gradient. Correlations in common use consider liquid/gas interactions - the oil and water are lumped together as one equivalent fluid. They are therefore more correctly termed 2-phase flow correlations. Depending on the particular correlation, flow regimes are identified and specialised holdup and friction gradient calculations are applied for each flow regime. As yet, no single correlation performs better than others for all flow conditions. Fancher Brown
is a no-slip hold-up correlation that is provided for use as a quality control. It gives the lowest possible value of VLP since it neglects gas/ liquid slip it should always predict a pressure which is less than than the measured value. Even if it gives a good match to measured downhole pressures, Fancher Brown should not be used for quantitative work. Measured data falling to the left of Fancher Brown on the correlation comparison plot indicates a problem with fluid density (i.e PVT) or field pressure data.
Hagedorn Brown
performs well in oil wells for slug flow at moderate to high production rates (well loading is poorly predicted). Hagedorn Brown should not be used for condensates and whenever mist flow is the main flow regime. It under predicts VLP at low rates and should not be used for predicting minimum stable rates.
Duns and Ros Modified
The Duns and Ros Modified correlation is derived from the Duns and Ros Original correlation. The original correlation was modified by Petroleum Experts to overestimate the pressure drop in oil wells for the slug flow regime. This correlation should only be used for quality checking of the input well test data. This correlation should not be used for calculating the pressure drop in the wellbore or pipelines and hence should not be used for lift curve generation either.
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The Duns and Ros Original Correlation is derived from the original published method. In PROSPER the original Duns and Ros correlation has been enhanced and optimised for use with condensates. This correlation performs well in mist flow cases and may be used in high GOR oil wells and condensate wells.
Petroleum correlation combines the best features of existing correlations. Petroleum Experts Experts correlation uses the Gould et al Flow Map and for the various flow regimes we use the following: Bubble flow:
Wallis and Griffith
Slug flow:
Hagedorn and Brown
Transition:
Duns and Ros
Annular Mist flow: Duns and Ros Petroleum includes the features of the PE correlation plus original work on Experts 2 predicting low-rate VLPs and well stability. The PE2 correlation has been tested for numerous high flow rate cases and found to provide a good estimate of the pressure drops. Examples include the Thunderhorse asset in GOM with wells exceeding 40000blpd and Yadana in Thailand which had gas wells with 7in casing capable of producing up to 1Bscf/day. PE2 has also been externally tested as the most reliable well flow correlation irrespective of fluid type, flow regime or pipe specification. J.E. Norman Liley; Stuart Oakley; "Downhole Pressure Boosting in Natural Gas Wells: Well Candidate Selection and Project Progress" SPE 96037-PA Petroleum includes the features of the PE2 correlation plus original work for Experts 3 viscous, volatile and foamy oils. Petroleum is an advanced mechanistic model suitable for any angled wells Experts 4 (including downhill flow) suitable for any fluid (including Retrograde Condensate). Especially good for pipeline pressure drop calculations and instability calculations (detecting the conditions at which instability will occur). Petroleum The PE5 mechanistic correlation is an advancement on the PE4 Experts 5 mechanistic correlation. PE4 showed some instabilities (just like other mechanistic models) that limited its use accross the board. PE5 reduces the instabilities through a calculation that does not use flow regime maps as a starting point. PE5 is capable of modelling any fluid type over any well or pipe trajectory. © 1990-2011 Petroleum Experts Limited
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This correlation accounts for fluid density changes for incline and decline trajectories. The stability of the well can also be verified with the use of PE5 when calculating the gradient traverse, allowing for liquid loading, slug frequency, etc. to be modelled. Orkiszews correlation often gives a good match to measured data. However, its formulation includes a discontinuity at velocity = 10 ft/s in its calculation ki method. The discontinuity can cause instability during the pressure matching process, therefore its use is not recommended. Beggs and is primarily a pipeline correlation. It generally over-predicts pressure drops in vertical and deviated wells. Brill Gray
correlation gives good results in gas wells for condensate ratios up to around 50 bbl/MMscf and high produced water ratios. Gray contains its own internal PVT model which over-rides PROSPER's normal PVT calculations. For very high liquid dropout wells, use a Retrograde Condensate PVT and the Duns and Ros correlation.
Barnea Criteria Slugging Calculations Note There is no universal rule for selecting the best flow correlation for a given application. It is recommended that a Correlation Comparison always be carried out. By inspecting the predicted flow regimes and pressure results, the User can select the correlation that best models the physical situation. MultiPhase Flow Fundamentals Single-Phase Energy Balance Equation Consider an element of pipe through which a fluid is flowing at a steady-state rate. The energy associated with a unit mass of fluid entering the element plus any shaft work done by the fluid plus any heat exchanged with the surroundings plus change of energy with time must equal the energy leaving the pipe element. The energy balance can be expressed as: d(PV) + dU + d(1/2 u2) + d(gCosL) = Q W Pressure Internal Kinetic Potential Heat External energy energy energy energy added work done The energy per unit mass entering the element is the sum of the internal and kinetic energy terms at that point. This must equal the sum of the internal and kinetic leaving the element plus the heat loss (or gain) from the element plus any work done by the fluid. PROSPER Manual
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For single phase conditions, the terms can be expressed as follows: d(PV) = PdV + VdP dU = (Q + F - PdV) (F is a frictional dissipation term) d(1/2 u2) = udu d(gCosL) = gCos.dL the energy balance can be written: (PdV + VdP) + (Q + F - PdV) + udu + gCos.dL = Q - W which simplifies to: VdP + udu + gCos.dL + F + W = 0 Assuming no external work is done on the system dP dF du = rgCosf + r +G dL dL dL (G is the mass flow rate) This is the single phase pressure gradient expression: æ dP ö æ dP ö æ dP ö æ dP ö -ç ÷ =ç ÷ +ç ÷ +ç ÷ è dL ø Total è dL ø Gravity è dL ø Friction è dL ø Acceleration For MultiPhase flow of oil, water and gas, the energy balance is derived in a similar manner. Multi-Phase Energy Balance Equation The energy per unit mass entering the pipe element is the sum of internal and kinetic energy at point L: é é ug2 ù é é uo2 ù uw2 ù ù r q U + + r q U + + r q U + ê g gê g ú o oê o w wê w ú úú 2 úû 2û 2 û úû êë ë ë êë L The energy per unit mass leaving the pipe element is the sum of internal and kinetic energy at point L+L: é é ug2 ù é é uo2 ù uw2 ù ù r q U + + r q U + + r q U + ê g gê g ú o oê o w wê w ú úú 2 úû 2û 2 û úû êë ë ë êë L +d L
Heat exchange to or from the pipe is proportional to the temperature difference between the well fluids and the surroundings, the heat transfer area and the overall heat transfer coefficient Uc: dQ = U c (Tf - Te ) p D.d L dt The rate of work done by the system is the change in potential energy plus the change of enthalpy (h = U + /). Defining the mass flow rate in the pipe as: é pD 2 ù m=ê ú a g r g ug + a o r o uo + a w r w uw ë 4 û
(
)
The energy balance can be written for multi-phase flow as follows: d r g q g ( hg + ug2 / 2 ) + r o qo ( ho + uo2 / 2 ) + r w qw ( hw + uw2 / 2 ) = dL pDU c (Tf - Te ) + mgCosf
[
]
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Summing the enthalpies for all phases, this can be simplified to: dH du 1 dQ +u - gCosf + =0 dL dL m dL The pressure traverse for a well or pipeline can be computed by numerical integration of the pressure gradient equation over the length of the pipe. This requires knowledge of the proportion of each phase present and its density for the pressure and temperature of each incremental pipe segment. The densities and gas/liquid proportions are found from a PVT model. To find the total pressure gradient requires the above equation to be simultaneously solved for pressure and temperature. If the flowing temperature profile is available, then the equation can be evaluated directly for pressure. In the majority of applications, the flowing temperature has a minor effect on the calculated pressure drop. If the flowing temperature profile is available, the pressure gradient can be evaluated directly. Total Pressure Gradient Components The total pressure gradient is the sum of 3 terms: rCosf Gravity The gravity term reflects the fluid density and the angle of deviation from vertical. Evaluation of the fluid density is straightforward for single-phase applications. For MultiPhase flow, the mixture density is required. This requires knowledge of the density of each phase and the proportion of the pipe occupied by each (holdup). ru 2 f 2D Friction The frictional pressure gradient is proportional to the friction factor f and the square of the flow velocity. The frictional pressure gradient comprises a greater proportion of the total pressure drop as the flow velocity increases. du ru dL Acceleration The magnitude of the acceleration component of the total pressure gradient is insignificant except when the produced fluid is rapidly changing in velocity e.g. in a gas well operating with low well head pressure.
In a properly designed oil well completion, the gravity component comprises around 75% of the total pressure gradient. The accuracy of liquid density and holdup values are the main factors affecting the accuracy of the total pressure gradient calculations. Multi-Phase Flow The density difference between gas and either water and oil is far greater than the density difference between oil and water. So-called multi-phase flow correlations lump oil and water together as liquid and calculations are based on liquid/gas interactions. Such flow correlations are more accurately described as 2-phase methods. The calculation errors resulting from lumping the water and oil together have been found PROSPER Manual
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to be insignificant for the majority of oil well pressure calculations. Errors have been observed for large diameter tubing in deviated wells. Holdup Holdup is the proportion of the pipe cross-section occupied by liquid as shown in the following sketch:
Since the sum of the area occupied by liquid plus that occupied by gas must equal the total pipe cross-section, the following relation must always be obeyed: hl = (1 - hg ) The mixture density is calculated from the phase densities and the liquid holdup. r m = r l hl + r g (1 - hl ) The liquid density is that of the mixture of oil and water. Estimation of the liquid holdup (and hence the mixture density) for a wide range of flow conditions is a main goal of flow correlations. Superficial Velocity The superficial velocity is the velocity of each phase if it were flowing alone in the pipe. For the prevailing pressure and temperature, the superficial velocities are calculated from the volumetric flow rate and pipe cross-sectional area as follows: Vsup l = q l / A p Vsup g = q g / A p
Defining the mixture velocity as the sum of the phase superficial velocities (Vm = Vsupl + Vsupg), the 'no-slip' holdup can be calculated: hno - slip =
Vsup l Vsup l + Vsup g
Slip The density difference between gas and liquid results in a buoyancy force between them. In inclined flow, the gas will rise up through the liquid. This increases the gas flow velocity relative to the liquid. Since the gas is travelling faster than the oil, a smaller area of the pipe will be required to produce the same mass flow of gas. The effect of slip is therefore to increase the liquid holdup, and hence the mixture density. The amount of gas/liquid slip depends on factors such as density difference, the relative © 1990-2011 Petroleum Experts Limited
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proportions of oil and gas, flow velocities and pipe diameter. A major factor is the flow regime. Gravity vs Friction Head At low flow rates, the increase in mixture density due to gas/liquid slip can be significant. As rates increase, the flowing velocity increases and the liquid 'catches up' with the gas. At very high flow rates, slip is insignificant since both phases are travelling with virtually the same velocity. On the other hand, the frictional loss increases rapidly with flow velocity. The total gradient is the sum of gravity, friction and acceleration terms. The flowing bottom hole pressure displays a minimum when the rate of change of the gravity gradient equals the rate of change of friction gradient. The rate corresponding to the minimum flowing bottom hole pressure is termed the minimum stable rate. Rates less than this are termed 'head dominated'. Higher rates are termed 'friction dominated'. Wells cannot sustain steady state flow for rates less than the minimum stable rate. The unstable production is termed 'heading' where alternate slugs of oil and gas are produced. While some wells may be able to continue unstable production for rates below the minimum stable rate, VLP correlations cannot be used, since they apply only to steady state flow conditions. Flow Regimes Observation of flow loop experiments has identified characteristic patterns that occur under varying conditions of multi-phase flow. Different flow patterns occur depending on many factors including the proportion of phases present, flow velocity, viscosities and interfacial tension. Most methods use 'flow maps' to identify flow regimes. A flow map is a presentation of flow regime as a function of dimensionless liquid and gas velocity parameters. The correlating parameters vary between authors. Gould et al Flow Map Frictional losses and liquid holdup can vary widely between flow regimes. Most pressure loss correlations require accurate flow regime prediction so that the appropriate calculation methods can be applied. The major flow regimes encountered in producing wells are discussed below: Single Phase Oil An undersaturated reservoir producing above bubble point pressure will have single phase oil production at the sand face. As the oil is produced towards surface, the wellbore pressure will decline in response to the reduction in hydrostatic head and frictional losses until the bubble point pressure is reached. Bubble Flow When the bubble point is reached, small evenly dispersed gas bubbles within the liquid will form. As both the liquid and gas expand, the flowing velocity will increase. This relatively well ordered flow regime can be modelled with a good degree of precision. Slug Flow PROSPER Manual
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As the pressure reduced further, more gas is evolved. The gas bubbles interact and coalesce to form slugs of gas that can occupy most of the pipe cross-section. Production is by alternate slugs of liquid and gas. This moderately chaotic flow regime can be modelled with acceptable precision. Annular Mist As the pressure decreases, both the volumetric proportion and the flow velocity of the gas increases greatly. A liquid film forms on the walls of the pipe and gas production occurs through the central pipe core. Some fine liquid droplets can be entrained in the gas as a mist. Transition Flow Regimes For conditions that fall between the main flow regimes described above, transitional flow regimes may be observed. The onset of highly chaotic flow regimes can be difficult to predict. Pressure drop correlations generally handle transition flow regimes by averaging results calculated using the adjacent fully developed flow regime methods. Although many methods have been proposed, the prediction of flow regimes is imprecise and remains the subject of on-going research. PVT Pressure loss correlations require values for the in-situ gas/liquid ratio, flow velocities, fluid densities and viscosity for the entire range of temperatures and pressures in the calculations. The accuracy of pressure gradient calculations critically depends on the accuracy of fluid density values used. The following example (in field units) illustrates how surface flow rates and PVT data are used to calculate densities and velocities at downhole conditions. Densities If the surface densities of oil, water and gas are o ,w and g. at standard conditions, the corresponding densities at downhole conditions are: Rsg g (0.0764) g o (62.4) + 56146 . ro = Bo g rw = w Bw g g (0.0764) rg = Bg Velocities Superficial velocities are calculated from the surface oil production at standard conditions, solution GOR and the water cut. Defining: WOR = qw / qo and GLR = Rs * (1 - Water cut) and Ap = d2 / 4
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qo WCut VsL = 86,400 Ap 561 .
1 ö ì æ æ WOR ö ü ÷ + Bw ç ÷ í Bo çè è 1 + WOR ø ýþ 1 + WOR ø î
qo ì 1 öü æ ÷ý íGLR - Rs çè WCut î 1 + WOR ø þ Vsg = Bg 86,400 Ap
These basic parameters at downhole conditions, together with gas and liquid viscosities are passed to the flow correlation for calculation of the pressure gradient terms. Black oil and compositional methods may be used to predict PVT properties. For oil wells, the liquid density is the most important PVT parameter. Prediction of liquid density is a weakness of compositional PVT methods. The use of compositional PVT cannot be recommended for the majority of oil well pressure loss calculations. Historical Development Methods of modeling vertical two-phase flow can be divided into 3 classes in order of complexity: 1. Liquid holdup and friction losses are expressed an equivalent single phase energy loss factor. The flowing mixture density is used in place of the in-situ mixture density to calculate the gravity component. No attempt is made to identify flow regimes. 2. The effect of two-phase holdup and friction losses are evaluated separately. No attempt is made to identify flow regimes. 3. Flow regimes are identified and correlations specialised to flow regimes are used to estimate holdup and friction losses. The first experimental work in the field of multi-phase flow is generally credited to Davis and Weidner. Most pressure loss correlations have been developed from laboratory experimental work with air-water mixtures in short lengths of small diameter tubing. Thus the effects of large scale inter-phase mass transfer are not included. The results attempt to correlate liquid holdup and tubing wall friction with measured fluid properties and flowing phase fraction. Table 1 shows those correlations that have made some contribution to the problem of vertical MultiPhase flow. Poettmann and Carpenter developed a simple practical model, but its simplicity limits its accuracy. They related the irreversible energy losses of 49 well tests with a Fanning type friction factor term which was in turn related to the Reynolds number of the fluid mixture. This correlation is typical of a Category 1 method as defined above. Baxendall extended the Poettmann and Carpenter method to higher flow rates and Fancher and Brown applied the same method to 94 tests from an experimental well . Fancher and Brown introduced produced gas-liquid ratio as an additional parameter in the friction factor correlation. Much of the early work in developing both flow maps and correlations have been attributed to Griffith and Wallis and Duns and Ros. They concentrated on the definition of the flow boundaries of the flow regimes and presented the results in the PROSPER Manual
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form of a flow pattern map. Ros and also Duns and Ros gathered laboratory data on pressure drop for two-phase flow and they considered the dependency of the flow regimes on dimensionless parameters. Hagedorn and Brown developed a correlation from 475 tests in a 1,500 foot experimental well using fluids with viscosities up to 110 centipoise. An average mixture density corrected for downhole conditions was used for calculating friction and acceleration pressure losses. Liquid holdup was not measured directly - it was calculated from the total measured pressure loss. Further work by Brill and Hagedorn has improved the correlation prediction of holdup and slip and included the Griffith bubble flow correlation. Orkiszewski developed a pressure drop prediction method based on a new flow pattern map and a combination of features from existing correlations. He combined the work of Griffith for bubble flow and that of Griffith and Wallis for slug flow together with the Duns and Ros correlation for mist flow. In addition, new friction and density correlations for slug flow based on a liquid distribution parameter were developed. The data of Hagedorn was used to develop a correlation with tubing size, superficial mixture velocity and liquid viscosity. Aziz et al developed a mechanistically based model and concentrated their research on the bubble and slug flow regimes. Predictions for 48 wells were compared to field data and with the predictions from Orkiszewski, Duns and Ros and Hagedorn and Brown with favourable results. Beggs and Brill developed a correlation for prediction of pressure gradient and holdup from experiments carried out in 1 inch and 1 1/2 inch smooth circular pipes at any angle of inclination. They found that in inclined flow, the liquid holdup reaches a maximum about 50º from horizontal and a minimum at around -50º from horizontal. The result that the holdup is approximately equal at 90 and 20 confirms the observation that vertical flow correlations can often be successfully used in horizontal flow. The Beggs and Brill correlation is the first method to explicitly account for the effect of deviation on holdup. Cornish developed a simple homogeneous flow model which assumes no slippage occurs in high flow rate wells. However for two-phase Reynolds numbers <105, slip will be significant and the method may not apply. VLP Correlations The primary purpose of a flow correlation is to estimate the liquid holdup (and hence the flowing mixture density) and the frictional pressure gradient. This section details the methods used by some of the most widely applied correlations. Hagedorn Brown The Hagedorn-Brown correlation is probably the most widely applied of all oil well VLP correlations. It works well for bubble and slug flow regimes in a wide range of applications. At low flow rates it under-predicts flowing pressures. This can result in optimistic predictions for minimum stable flow rates. © 1990-2011 Petroleum Experts Limited
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The Hagedorn-Brown correlation was developed from data obtained from a 1500 ft test well using fluids with a wide range of viscosities. The liquid holdup was not measured, but was back-calculated to satisfy the measured pressure gradient after the pressure drop due to friction and acceleration were accounted for. The liquid holdup is not a true indicator of the proportion of the pipe occupied by fluid, it is merely a correlating parameter. Hagedorn and Brown found the liquid holdup could be correlated to four dimensionless parameters: NLV = 1.938 VSL (L/L)1/4 Liquid Velocity Number NGV = 1.938 VSG (L/L)1/4 Gas Velocity Number Nd = 120.872 d (L/L)1/2 Pipe Diameter Number NL = 0.15726 L (1/LL3)1/4 Liquid Viscosity Number The above expressions are dimensionless when the parameters are expressed in the appropriate field units as shown below: VsL = ft/sec Liquid superficial velocity VsG = ft/sec Gas superficial velocity L = lbm/ft3 Liquid density L = dyne/cm Interfacial tension L = centipoise Liquid viscosity d = feet Pipe diameter The liquid comprises both oil and water, therefore the issue of calculating mixture properties arises. In the Hagedorn-Brown correlation a weighted average approach is used: L = O fO + W fW L
=
O fO + W fW
L
=
O fO + W fW
Where the fractional flow of oil and water are defined as follows: fO = qO/(qO+qw) fW
=
qW/(qO+qw) = 1 - fO
The correlating function is entered with a value of CNL. The corrected liquid number is read from a plot of CNL vs NL: The secondary holdup correction factor is determined from a correlation of NGV, NL and Nd. Once the correction factors have been determined, the holdup can be calculated. The pressure gradient due to elevation change (gravity term) is calculated from: g æ dP ö = r h + r g (1 - hl ) ç ÷ è dL ø Gravity g c l l The pressure gradient due to friction is given by: r f Vm2 æ dP ö = f ç ÷ è dL ø Friction 2 gc d PROSPER Manual
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where: r 2n rs r s = r l hl + r g (1 - hl ) rf =
r n = r l l l + r g (1 - l l ) V M = VSL + VSG l l = VSL / V M
The friction gradient can be written in terms of the mass flow rate (w) as follows: w2 æ dP ö = f ç ÷ è dL ø Friction 2 g c dA 2 r s This expression simplifies to: w2 æ dP ö = f ç ÷ è dL ø Friction 2.9652*1011 r s d 5 Where: w = mass flow rate lbm/day s = density based on liquid holdup lbm/ft3 d = pipe inside diameterfeet f = two phase friction factor dimensionless The two-phase friction factor is correlated with a two-phase Reynolds number using the standard Moody diagram. The two-phase Reynolds number is defined as follows: r V d N Re = n m ms where: m s = m hLL * m (g1- hL )
The acceleration due to acceleration is given by: r s D(Vm2 ) æ dP ö = ç ÷ è dL ø Acceleration 2 g c dL Where Vm is the difference in mixture velocity between the inlet and outlet ends of a pipe element. The Acceleration gradient is applied as a correction (Ek) to the sum of the Gravity and Friction gradients as follows: dL æ dP ö r s D(Vm2 ) Ek = ç ÷= dP è dL ø 2 g c dP the total pressure drop can be calculated from: æ dP ö æ dP ö +ç ÷ ç ÷ è ø dL Gravity è dL ø Friction æ dP ö = ç ÷ è dL ø Total 1 - Ek The refinements suggested by Brill and Hagedorn have been implemented in PROSPER : © 1990-2011 Petroleum Experts Limited
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· ·
Griffith correlation for bubble flow. Limit on liquid holdup to be always greater than the no-slip holdup.
Some additional refinements have been added to the basic Hagedorn-Brown correlation: · Beggs and Brill deviation correction for liquid holdup. · Explicit calculation of Acceleration term instead of using the Ek correction method. Field experience has shown that Hagedorn Brown gives excellent results for oil wells in bubble and slug flow away from the gravity dominated flow region. Errors are greatest for large bore deviated wells in the 35-70º range with moderate water cuts where water/ oil slip may be significant. Duns and Ros The Duns and Ros correlation is the result of an extensive laboratory study in which liquid holdup and pressure gradients were measured. Correlations were developed for slip velocity (from which the holdup can be calculated) and friction factor for 3 distinct flow regimes. The flow regimes are defined as functions of the dimensionless quantities NGV, NLV, La, Ls, Lm and Nd where: 1
N GV
ær ö = Vsg ç L ÷ è gs ø
N LV
ær ö = VsL ç L ÷ è gs ø
1
æ r gö Nd = d ç L ÷ è s ø
1
4
4
2
1
æ g ö NL = m L ç ÷ è r Ls 3 ø
4
Ls = 50 + 36 NLV Lm = 75 + 84 NLV0.75 Flow regimes are determined using the following relations: Region I (Bubble) 0 <= Ngv <= ( L1 + L2 * NLV ) Region II (Slug) ( L1 + L2 * NLV < Ngv < ( 50 + 36NLV ) Region III (Mist) Ngv > ( 75 + 84NLV0.75 ) Duns and Ros Flow Map Duns and Ros developed a dimensionless slip velocity correlation from which the actual slip velocity and liquid holdup can be calculated using the following relations: 1
æ r ö S = Vs ç L ÷ ès L gø
4
where:
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Vs = V g - Vl =
Vsg (1 - h L )
-
604
VsL hL
Solving for liquid holdup yields: hs =
[
Vs - Vm + (Vm - Vs ) 2 + 4VsVsL
]
2
2Vs
The procedure for calculating the gravity pressure gradient is: 1. Calculate the dimensionless slip velocity S using the appropriate correlation. The correlation for S is different for each flow regime. 2. Solve for the slip velocity, Vs 3. Solve for the liquid holdup hL 4. Calculate the mixture density, s = LhL + g(1-hL) 5. Calculate the gravity pressure gradient g æ dP ö = r ç ÷ è dL ø Gravity g c s Bubble Flow Regime The Bubble Flow regime is defined by a Gas Velocity number falling between zero and an upper limit (0 <= Ngv <= L1 + L2NLV). For bubble flow, the parameters are calculated as follows: Dimensionless slip velocity: 2 N gv ù 'é S = F1 + F2 N LV + F3 ê ú ë1 + N Lv û The bubble slip velocity numbers F1 F2 F3 and F4 are correlated with the liquid viscosity number NL. F3' is obtained from: F F3' = F3 - 4 Nd The Duns and Ros friction term for bubble flow is given by: r V V æ dP ö = f m L SL m ç ÷ è dL ø Friction 2 gc d
From experimental data, Duns and Ros obtained the following expression for fm: f m = f1 f 2 / f 3
f1 is obtained from the Moody diagram as a function of the liquid Reynolds number: r V d N Re L = L SL mL Note that for low values of Reynolds number corresponding to laminar flow conditions that the friction factor becomes independent of pipe roughness. The factor f2 is a correction for the in-situ gas - liquid ratio. The factor f3 is an additional correction for both liquid viscosity and in-situ gas-liquid ratio. It becomes important for viscosities greater than approximately 50 centistokes.
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æ Vsg ö f 3 = 1 + f1 ç ÷ è 50VsL ø
1
2
The acceleration term is insignificant for the bubble flow regime and is therefore not calculated. Slug Flow Regime For the slug flow regime ( L1 + L2 * Nlv < Ngv < ( 50 + 36nlv )) the dimensionless slip velocity is calculated as follows: ( N gv ) 0.982 + F6' S = (1 + F5 ) (1 + F7 N Lv ) 2 The slug slip velocity numbers F5, F6 and F7 are found from a plot as a function of liquid viscosity number NL: The friction pressure gradient is calculated using the same procedure as for bubble flow. The acceleration term is considered to be negligible in the slug flow regime. Mist Flow Regime For the Mist flow regime ( Ngv > ( 75 + 84 Nlv0.75 )), the slip velocity is taken as zero. This is because with the high gas flow rates, the liquid and gas travel with essentially the same velocity. With no slip, the mixture density can be calculated directly from: æ Vsg ö æV ö r n = r L l L + r g l g = r L ç sL ÷ + r g ç ÷ è Vm ø è Vm ø In the mist flow regime, the friction term is based on the gas phase only: r gVsg2 æ dP ö = f ç ÷ è dL ø Friction 2 gc d The friction factor f is read from the Moody diagram as a function of the gas Reynolds number: r gVsg d N Re = mg In mist flow, there is a film of liquid on the pipe wall. The ripples of the wall film cause a drag on the gas. This process is governed by a form of the Weber number: r gVsg2 e N We = sL Liquid viscosity also has an influence which is accounted for by making Nwe a function of a dimensionless number containing the liquid viscosity: m 2L Nm = r Ls L e
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The value of pipe roughness may be very small, but /d never becomes smaller than the value for the pipe itself. At the transition to slug flow, /d approaches 0.5. Between these limits, /d can be calculated from the following equations: e 0.0749s L N We N m < 0.005: = d r gVsg2 d Values of f for the mist flow regime can be found for /d > 0.05 from: é ù 1 ú*4 f =ê 1.73 êë 4 Log10 (0.27e / d ) úû As the wave height on the walls increases, the actual area available for flow of gas is reduced to d-. Duns and Ros suggested that the prediction of friction loss could be refined by substitution of (d-) for d and Vsg d 2
[
]
(d - e ) 2
for Vsg throughout the calculation of friction gradient. In this case, the determination of roughness is iterative. In mist flow, the acceleration term can be written as: VmVsg r n æ dP ö = ç ÷ è dL ø Acceleration g c pdL Define an acceleration parameter Ek as follows: VmVsg r n Ek = gc p then the total pressure gradient can be calculated from æ dP ö æ dP ö +ç ÷ ç ÷ è ø dL Gravity è dL ø Friction dP = dL 1 - Ek
Transition (Slug-Mist) Flow Regime For the region (Ls < Ngv < Lm) linear interpolation of the total pressure gradients is used to determine the total pressure gradient. This means that when Ngv falls between Ls and Lm, pressure gradients must be calculated using both slug flow and mist flow correlations as follows: dP æ dP ö æ dP ö = Aç ÷ + Bç ÷ è dL ø Slug è dL ø Mist dL
where: A=
Lm - N gv Lm - Ls
,B =
N gv - Ls Lm - Ls
= 1- A
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others. It is particularly useful for condensate wells. Although the accuracy of pressure gradient predictions in slug flow is generally inferior to Hagedorn-Brown, prediction of minimum stable flow rates using the minimum value of the Duns and Ros flowing bottom hole pressure is generally accurate. In PROSPER additional refinements have been made to the basic Duns and Ros method: · Beggs and Brill deviation correction for holdup is implemented · Gould et al flow map which more accurately predicts the onset of mist flow for some conditions · Explicit calculation of the Acceleration term Gray Gray is a gas and gas condensate multi-phase correlation used in the API 14B Subsurface Safety Valve sizing program. The Gray correlation contains an internal Black Oil PVT model. The internal PVT routines override the primary PROSPER PVT model in use. This correlation gives good results in gas wells for condensate ratios up to around 50 bbl/MMscf and high produced water ratios. For very high liquid dropout wells, use a Retrograde Condensate PVT and the Duns and Ros correlation. In condensate wells, the liquid holdup is small or zero at the sand face, and increases as the pressure reduces towards the surface. Depending on the condensate PVT properties, the liquid holdup can reduce to zero as the pressure is further reduced. This is in contrast to oil wells where the gas fraction always increases towards the surface. The effect of holdup on the friction gradient can be adequately expressed as a change in pipe wall roughness rather than rely on a Moody friction factor. The Gray correlation utilises the following parameters: g(r L - r g ) D 2 Vso + Vsg r 2mVsm4 Nv = ; Nd = ;R = gt m ( r L - r g ) tm Vsg where: m = Mixture density Vsm = Superficial mixture velocity m = Mixture surface tension L,g = Liquid and gas densities D = Pipe diameter Vso,w,g = Oil, water, gas superficial velocity The gas volume fraction is estimated using: fg = (1 - ec) / (R + 1) where: C = -2.314 AB A = Nv (1 + 205.0 / Nd) B = 0.0841 (1 - 0.0554 ln (1 + 730 R / (R + 1)))
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The mixture surface tension is defined as: q t + 0.617q wt w tm = o o q o + 0.617q w The Katz correlations for oil and water surface tensions are as follows: w = (2.115 - 0.119 ln P) * (0.174 - 2.09 * 10-4 * (T - 460)) o = 0.044 - 1.3 * 10-4 (T - 460) * ( PD - P) / (PD - 2120)2.5 where: PD = Dew point pressure T = Temperature (ºR) The Colebrook-White equation is used to calculate the friction factor with roughness evaluated as follows: r = rL = 28.5 m / m V2sm R >= 0.007 r = rg + (rL - rg) R / 0.007 R < 0.007 subject to the limit r >= 2.77 * 10-5 Gray gives good results in gas wells for condensate ratios up to around 50 bbl/MMscf and high produced water ratios for pressure loss and prediction of minimum stable flow rates.. For very high liquid dropout wells, use a Retrograde Condensate PVT and the Duns and Ros correlation.
Aziz Govier and Fogarisi The Aziz et al correlation recognises four flow regimes. The Duns and Ros method is used for mist flow and new correlations are presented for bubble and slug flow. The slug-mist transition is handled using the Duns and Ros interpolation method. The Aziz et al correlation can be classed as a 'mechanistic' model. This tag is applied since some aspects of the holdup are calculated in a manner that assigns a physical significance to parameters such as the bubble rise velocity. These parameters are then used to enter empirical correlations as in other methods. Flow regimes are defined using the following variables: NX
é rg ù = Vsg ê ú ë 0.0764 û
1
3
1
é 72 r L ù 4 N Y = VsL ê ú ë 62.4s L û Flow regime numbers are defined as follows: N1 = 0.51 (100 NY)0.172 N2 = 8.6 + 3.8 NY N3 = 70 (100 NY)-0.152 where: VsL = ft/sec Liquid superficial velocity VsG = ft/sec Gas superficial velocity L = lbm/ft3 Liquid density © 1990-2011 Petroleum Experts Limited
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g L
= =
lbm/ft3 Gas density dyne/cm Gas/liquid interfacial tension
Bubble Flow For the bubble flow regime, (NX < N1) liquid holdup is given by: Vsg hL = 1 Vbf where: Vbf Vbf
= =
Bubble rise velocity in the flowing stream 1.2 Vm + Vbs 1
és L g( r L - r g ) ù 4 Vbs = 141 . ê ú r 2L êë úû and The bubble flow friction term is given by: r sVm2 æ dP ö =f ç ÷ è dL ø Friction 2 gc d
f is obtained from the Moody diagram using the Reynolds number: r V d N Re = L m mL The acceleration is considered to be negligible in the bubble flow regime. Slug Flow The slug flow regime is defined by (N1 < NX < N2 for NY < 4; N1 < NX < 2.65 for NY > 4). In the slug flow region, the liquid holdup is given by: Vsg hL = 1 Vbf Vbf = 12 . Vm + Vbs é gd ( r L - r g ) ù Vbs = C ê ú rL ë û
1
2
3.37 - N E ù é C = 0.345[1 - exp( -0.029 N V )] ê1 - exp ú m ë û
NE =
gd 2 ( r L - r g ) sL 3
é d gr L ( r L - r g ) ù NV = ê ú mL êë úû
and m is evaluated from the following table: NV m >250 10 PROSPER Manual
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250 > NV > 18 69 NV-0.35 <=18 25 The slug flow friction term is given by: r h V2 æ dP ö =f L L m ç ÷ è dL ø Friction 2 gc d f is obtained from the Moody diagram using the same Reynolds number as for Bubble flow. The acceleration term is considered to be negligible in the slug flow regime. Slug-Mist Transition Regime The transition regime is defined by (N2 < NX < N3 and NV < 4; transition flow does not exist for NY > 4). Pressure gradients are calculated using both slug and mist flow correlations. Linear interpolation is used to determine the total pressure gradient: dP æ dP ö æ dP ö = Aç ÷ + Bç ÷ è dL ø Slug è dL ø Mist dL where: A=
N3 - N X N - N2 ,B = X = 1- A N3 - N2 N3 - N2
Mist Flow Regime The mist flow regime is defined by (NX > N3 and NY < 4; NX > 26.5 and NY > 4). In mist flow, the Duns and Ros technique is used. Beggs and Brill The Beggs and Brill correlation can be used in both horizontal and inclined flow. It was developed from experimental data in 1 inch and 1 1/2 inch acrylic pipe which could be inclined at any angle. Air and water were the fluids used. Liquid and gas rates were varied to enable all flow patterns to be observed with the pipe horizontal. With a flow rate set up, the pipe inclination was varied so that the effect of angle on holdup could be observed. Holdup correlations were developed for each of three horizontal flow regimes. The liquid holdup is first calculated as if the pipe were horizontal and then corrected for pipe inclination. Beggs and Brill found that the holdup was a maximum at approximately +50º from the horizontal and a minimum at approximately -50º. Beggs and Brill modified their flow map from that originally published to include a transition zone between the segregated and intermittent flow regimes (see below). The following dimensionless parameters are used to identify the flow regime that would exist if the pipe were horizontal.
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N FR = lL =
Vm2 gd
VSL Vm
The Beggs and Brill flow regime numbers are: L1 = 316 L0.302 L2 = 0.0009252 L-2.4682 L3 = 0.5 L-6.738 The horizontal flow regimes are determined as follows: Segregated flow L < 0.01 and NFR < L1 L >= 0.01 and Nfr < L2 Transition flow L >= 0.01 and L2 <= NFR <= L3 Intermittent flow 0.01 <= L < 0.4 and L3 <= NFR <= L1 or L >= 0.4 and L3 <= NFR <= L1 Distributed flow L > 0.4 and NFR >= L1 or L >= 0.4 and NFR > L4 When the flow falls in the transition regime, the liquid holdup is calculated using both the segregated and intermittent expressions and linearly interpolated using the following weighting factors: A = (L3 - NFR) / (L3 - L2) B = 1-A The same equations are used to calculate liquid holdup for all flow regimes. The coefficients and exponents used in the equations are changed for each flow regime. Liquid holdup is given by: hL (f ) = hl (f ) Y where hL() is the holdup which would exist for the same flow conditions in a horizontal pipe. The equivalent horizontal holdup is given by: albL hL (f ) = c N FR where a, b and c are taken from the following table according to flow regime: Flow Pattern a b c Segregated 0.98 0.4846 0.0868 Intermittent 0.845 0.53351 0.0173 Distributed 1.065 0.5824 0.0609 with the constraint that hL() >= L. The effect of pipe inclination is accounted for using the parameter , the value of which is defined as follows: PROSPER Manual
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y = 1 + C(sin(18 . f ) - 0.333 sin 3 (18 . f ))
where is the actual angle of the pipe from horizontal. For vertical upward flow, = 90º and becomes: = 1 + 0.3 C where: e f g C = (1 - l L ) ln(dl L N LV N FR ) where d, e, f and g are determined for each flow regime from the following table: Horizontal Flow Pattern d e f g Segregated uphill 0.011 -3.768 3.539 -1.614 Intermittent uphill 2.96 0.305 -0.4473 0.0978 Distributed uphill No correction C=0 All flow patterns downhill 4.70 -0.3692 0.1244 -0.5656 with the restriction that C >= 0. The friction loss term is defined as: r nVm2 æ dP ö = f TP ç ÷ è dL ø Friction 2 gc d where: n=nL+gg éf ù f TP = f n ê TP ú ë fn û
The no-slip friction factor is determined from the smooth pipe curve on the Moody diagram or calculated using:
[
]
f n = 1 / 2 log[ N Re n / (4.5223 log N Re n - 38215 . )]
2
using the following Reynolds number: rV d N Re n = n m mn where: m n = m Ll L + m gl g
The ratio of the two phase to no-slip friction factor is calculated from: f TP = es fn where: S = ln (y) / (-0.0523 + 3.182 ln (y) - 0.8725 ln (y)2 + 0.01853 ln(y)4) and y=
lL hL ( f )
2
S becomes unbounded at a point in the interval 1 < y < 1.2. In this region, S is calculated using: © 1990-2011 Petroleum Experts Limited
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S = ln ( 2.2 y - 1.2) Although the acceleration pressure gradient is small, it is included for increased accuracy. r sVmVsg é dP ù æ dP ö = ç ÷ è dL ø Acceleration gc P êë dL úû If the acceleration term is defined as: r sVmVsg Ek = gc P The total pressure gradient can be expressed as: æ dP ö æ dP ö +ç ÷ ç ÷ è dL ø Gravity è dL ø Friction æ dP ö = ç ÷ è dL ø Total 1 - Ek where g æ dP ö = r ç ÷ è dL ø Gravity gc s
The approach of including the acceleration term as an overall correction factor to the total gradient is convenient and sufficiently accurate when the acceleration term is small. To improve accuracy when acceleration is large, PROSPER calculates the acceleration term explicitly and adds it to the Gravity and Friction terms to find the total pressure gradient. Orkizewski Orkizewski conducted an extensive study of existing correlations, comparing field data and calculated results. The Orkizewski correlation combines the Griffith and Wallis method for bubble flow with a new correlation for slug flow and the Duns and Ros method for mist flow. The data of Hagedorn and Brown was used as the basis for the slug flow correlation. Bubble Flow The bubble flow regime is defined by: Vsg / Vm < LB where: LB = 1.071 - (0.2281 Vm2 / d) The value of LB is constrained to be greater than 0.13. Liquid holdup in the bubble flow regime is given by: 1 ù 1é V hL = 1 - ê1 + m - (1 + Vm / Vs ) 2 - 4Vsg / Vs 2 ú 2 ë Vs û
[
]
The value of the bubble slip velocity Vs is taken to be constant at 0.8 ft/sec. The friction term is given by: PROSPER Manual
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r (V / h ) 2 æ dP ö = f L sL L ç ÷ è dL ø Friction 2 gc d
The friction factor f, is read from the Moody diagram using a Reynolds number defined as: r dV N Re = L sL hL m L The acceleration term is considered to be negligible in the bubble flow regime. Slug Flow The slug flow regime is defined by: Vsg / Vm > LB, and Ngv Ls. For slug flow, the two phase density is given by: r L (VsL + Vb ) + r gVsg rs = + r Ld Vm + Vb where is the liquid distribution coefficient and Vb = C1 C2 (gd)1/2 C1 and C2 are presented as functions of NReb and NReL where: r Vd N Re b = L b mL r V d N Re L = L m mL Vb can be calculated using the following expressions: For NReb <= 3000 Vb = (0.546 + 8.74 * 10-6 NRel ) (gd)1/2 For NReb >= 8000 Vb = (0.35 + 8.74 * 10-6 NRel ) (gd)1/2 For 300 < NReb < 8000 é é 1359 . m L ùù úú Vb = 12 êe + êe 2 + 1 2 úú ê ê r d L ë ûû ë where = (0.251 + 8.74 * 10-6 NReL ) (gd)1/2 Since Vb is a function of NReb and NReb is in turn a function of Vb, an iterative solution is required for Vb. The value of is calculated using different expressions depending on the mixture velocity and the continuous liquid phase as shown in the following table: Continuous Liquid Phase Mixture Velocity Equation for water <10 1 water >10 2 © 1990-2011 Petroleum Experts Limited
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oil <10 3 oil >10 4 Orkizewski did not define criteria for determining whether oil or water is the continuous phase. In a water / oil emulsion, water will generally be the continuous phase above a water cut of approximately 75%. Liquid distribution coefficient expressions: 1. = (0.013 log L) / d1.38 - 0.681 + 0.232 log Vm - 0.428 log d 2. = (0.045 log L) / d0.799 - 0.709 + 0.162 log Vm - 0.888 log d 3. = (0.0127 log (L + 1)) / d1.415 + 0.284 + 0.167 log Vm + 0.113 log d 4. = (0.0274 log (L + 1)) / d1.371 + 0.161 + 0.569 log d + X X = -log Vm (0.01 log (L + 1) / d1.371) + 0.397 + 0.63 log d The value of is constrained by the following limits: For Vm < 10 , >= -0.065 Vm -Vb (1 - r s / r L ) V + Vb For Vm > 10 , >= - m 0.065 Vm These constraints are designed to eliminate pressure discontinuities between flow regimes. However, significant discontinuities still occur at Vm of 10 ft/sec. This can cause significant problems, especially in large diameter pipes. Although Orkizewski can give excellent results in many wells, the use of Orkizewski is discouraged due to the danger of encountering a pressure discontinuity during pressure matching and VLP calculations. The friction term for slug flow is given by: ù r LVm2 é éVsL + Vb ù æ dP ö = f +dú ç ÷ ê ê ú è dL ø Friction 2 gc d ë ë Vm + Vb û û where f is taken from the Moody diagram using the Reynolds number: r dV N Re L = L m mL The acceleration term is considered to be negligible in the slug flow regime. Transition Flow The transition flow regime is defined by Lm > Ngv < Ls. The total pressure gradient is found by linear interpolation between the slug and mist flow boundaries using the interpolation scheme of Duns and Ros. Mist Flow The mist flow regime is defined by Ngv > Lm. The method of Duns and Ros is used for mist flow.
Pipeline Correlations Dukler PROSPER Manual
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The Dukler correlation was based on similarity analysis. The friction factor and liquid holdup correlations were developed from field data. Dukler's friction factor is given by: r V2 æ dP ö = f k m ç ÷ è dL ø Rriction 2 gc d where: rk =
r Ll 2
L
hL
+
r gl g 1 - hL
A normalised friction factor f / fn was correlated with a Reynolds number. The correlation can be expressed as: fn = 0.0056 + 0.5 NRek-0.32 where: r V d N Re k = k m mn Vm = VsL + Vsg m n = m Ll L + m gl g
The normalised friction factor is calculated from: f y = 1+ fn 1281 . - 0.478 y + 0.444 y 2 + 0.094 y 3 _0.00843y 4 where: y = -ln (L) An iterative procedure is required to find the liquid holdup. The holdup is a function of liquid fraction and Reynolds number. However, the Reynolds number is also a function of the holdup. NRek is plotted vs hL and L. The acceleration pressure gradient is given by: é r gVsg2 rLVsL2 ù 1 æ dP ö = Dê + ç ÷ ú è dX ø Acceleration gc dX êë 1 - hl hl úû or é r gVsg2 rLVsL2 ù 1 Ek = Dê + ú gc dP êë 1 - hl hl úû
The total pressure gradient is corrected using the Ek factor: é dP ù êë dX úû æ dP ö Friction = ç ÷ è dX ø Total 1 - Ek
Dukler Flanigan The Dukler Flanigan correlation calculates the friction gradient using Dukler's technique and applies Flanigan's inclined flow method. Flanigan developed a correlation from data taken on a 16 inch diameter pipeline. © 1990-2011 Petroleum Experts Limited
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Liquid holdup in the uphill sections of the pipeline were correlated with superficial gas velocity. Pressure recovery in downhill sections is ignored. The pressure drop due to the hills is calculated from: g æ dP ö = r h Z ç ÷ è dX ø Gravity gc L l å where Z is the sum of the vertical heights of all the hills. The holdup factor hL is a function of the superficial gas velocity and is determined from: 1 hL = 1 + 0.3264 × Vsg1.006 The Dukler-Flanigan total pressure gradient is found by summing the Dukler friction gradient and the Flanigan elevation pressure gradient then applying an acceleration correction. Dukler Flanigan has been found to give good results in a wide range of conditions.
2.15.3 C - Dietz Shape Factors List of the Dietz Shape factors:
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2.15.4 D - File Formats 2.15.4.1Introduction This appendix contains examples of some file formats used by PROSPER. For further details and advice regarding interfacing PROSPER with other applications, please contact Petroleum Experts Limited customer support.
2.15.4.2External PVT Tables PROSPER can directly import proprietary PVT table files generated by Petroleum Experts PVT Package. The following file format description can be followed to re-format PVT tables obtained from other sources. * TEST EXAMPLE OF AN OIL PVT TABLE IMPORT FILE * (BLANK LINES AND LINES WITH AN ASTERISK (*) IN COLUMN 1 * ARE IGNORED) * * UNITS for the imported PVT variables must be defined in field units * NUMBER OF TABLES 5 * * * * * * * * * * * * * * *
(MAX 10)
DATA COLUMN IDENTIFIERS - CAN BE IN ANY ORDER - COLUMNS CAN BE MISSING - ANY INDIVIDUAL ITEM > 3.4e35 = missing item
PRES GOR OFVF OVIS ODEN OCOM GFVF GVIS WVIS
PROSPER Manual
-
Pressure Gas-Oil Ratio] oil Formation Volume Factor oil Viscosity oil Density oil Compressibility gas Formation Volume Factor gas Viscosity water Viscosity May, 2011
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* WCOM * ZFAC * GDEN * CGR * OFVF GOR
620
water Compressibility Z Factor gas density Reservoir CGR OVIS ODEN PRES
* * TABLE IDENTIFIER RECORD * * N LINES TEMP BP * * N - Table Number * LINES - Number of lines in the table (max 15) * TEMP - Table Temperature * BP - Table Bubble Point Pressure (Dew condensate) 1 3 100 1300 1.21 453 .99 46 1.31 454 .98 47 1.41 455 .97 49 2 3 200 1310 2.21 553 .89 56 2.31 554 .88 57 2.41 555 .87 59 3 3 300 1390 3.21 653 .79 76 3.31 654 .78 77 3.41 655 .77 79 4 3 400 1400 4.21 753 .69 86 4.31 754 .68 87 4.41 755 .67 89 5 3 500 1800 5.21 853 .59 96 5.31 854 .58 97 5.41 855 .57 99
Point
for
2000 2010 2020 3000 3010 3020 4000 4010 4020 5000 5010 5020 6000 6010 6020
Note: Import table units must be defined in field units. Once the data has been imported the PROSPER units system can be used to display the values in any desired units.
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2.15.4.3Lift Curves The following is an example of a flowing well lift curve in ECLIPSE format: -- VFP TABLE for PRODUCER -VFPPROD 1 10430 'LIQ' 'WCT' 'GOR' / 100 1000 10000 / 114.696 514.696 5014.7 / 0 0.5 0.9 / 0.8 1 5 / 0/ 1 1 1 1 2002.17 1258.71 2733.66 / 1 1 2 1 1479.42 1083.09 2655.25 / 1 1 3 1 413.537 806.953 4503.13 / 1 2 1 1 3948.98 2376.35 3439.27 / 1 2 2 1 3619.42 1985.43 3270.18 / 1 2 3 1 494.134 928.339 3352.16 / 1 3 1 1 4913.94 4485.14 4672.16 / 1 3 2 1 4895.27 4343.38 4563.92 / 1 3 3 1 3925.4 2141.93 3460.48 / 2 1 1 1 3629.53 2559.11 3358.56 / 2 1 2 1 3539.7 2209.16 3216.7 / 2 1 3 1 1098.95 1408.86 4038.35 / 2 2 1 1 4817.47 3863.58 4190.39 / 2 2 2 1 4746.81 3540.81 3985.01 / 2 2 3 1 1916.92 1594.64 3434.72 / 2 3 1 1 5347.77 5166.94 5283.46 / 2 3 2 1 5337.64 5102.83 5210.6 / 2 3 3 1 5138.74 3590 4155.85 / 3 1 1 1 8202.54 8206.84 8494.42 / 3 1 2 1 8081.09 8085.64 8397.43 / 3 1 3 1 7436.73 7142.24 8450.65 / 3 2 1 1 9393.27 9014.22 9196.49 / 3 2 2 1 9308.64 8911.21 9105.01 / 3 2 3 1 8567.24 7774.64 8436.27 / 3 3 1 1 9912.37 9798.83 9952.61 / 3 3 2 1 9906.65 9776.86 9924.11 / 3 3 3 1 9813.74 9404.22 9463.37 / Gas Lifted Well (4 Variable) Lift Curves -- VFP TABLE for PRODUCER -VFPPROD 1 10430 'LIQ' 'WCT' 'GOR' / 100 1000 10000 / 114.696 1014.7 / 0.5 0.9 / PROSPER Manual
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0.82 5 / 0 0.2 0.5 / 1 1 1 1 4236.42 2633.35 3373.19 / 1 1 1 2 3825.95 2143.51 3274.85 / 1 1 1 3 3124.78 1852.12 3267.76 / 1 1 2 1 679.721 1006.21 3341.52 / 1 1 2 2 663.546 996.833 3405.81 / 1 1 2 3 641.284 977.228 3341.56 / 1 2 1 1 4983.68 4569.28 4613.82 / 1 2 1 2 4855.84 3445.19 4260.77 / 1 2 1 3 4234.42 2708.11 3888.35 / 1 2 2 1 4324.78 2288.63 3403.99 / 1 2 2 2 3770.29 1978.18 3361.59 / 1 2 2 3 2893.22 1811.06 3390.73 / 2 1 1 1 5416.3 4901.7 4903.34 / 2 1 1 2 5416.24 4900.79 4902.04 / 2 1 1 3 5416.15 4899.42 4900.17 / 2 1 2 1 4853.52 2622.82 3962.47 / 2 1 2 2 4853.36 2606.9 3962.25 / 2 1 2 3 4853.12 2591.41 3961.94 / 2 2 1 1 5925.14 5771.07 5819.76 / 2 2 1 2 5925.09 5770.6 5819.25 / 2 2 1 3 5925.01 5769.9 5818.5 / 2 2 2 1 5814.71 4954.63 4912.08 / 2 2 2 2 5814.64 4953.02 4911.18 / 2 2 2 3 5814.53 4950.61 4909.88 /
2.15.4.4IPR * * This is an example IPR input file * The format is pressure, rate, curve value * The numbers can be space, tab or comma delimited * Up to twenty points per curve, up to five curves * *Blank lines or lines with an asterisk (*) in the first * column are ignored. * 0 5000 1000 1000 4000 1000 2000 3000 1000 3000 2000 1000 4000 1000 1000 © 1990-2011 Petroleum Experts Limited
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5000
0 1000
* * Next curve * 0 3000 2000 1000 2000 2000 2000 1000 2000 3000 0 2000
2.15.4.5ESP PUMPS * Blank lines or lines begining with an asterisk are ignored. * The format for the pump data is * Line 1 Manufacturer pumpname size (ins) frequency(hz) Min. rte Max. rate No. of Stages * Line 2 six coefficients for head curve (ft of water) * Line 3 six coefficients for power curve (HP) * Curves are polynomials of the form * Y = AO + A1*x + A2*x*2 + A3*x**3 + A4*x**4 + A5*x**5 **************************** **************************** **************************** *** CENTRILIFT PUMPS **************************** **************************** ****************************
***
CENTRILIFT DC-800 3.38 60 550 950 1 * A5 A4 A3 A2 A1 -1.695826E-14 3.474714E-11 -3.873426E-08 2.06500E+01 3.389608E-16 -6.347699E-13 1.397720E-10 9.70000E-02 CENTRILIFT DC-1000 3.38 60 700 1300 1 0.0000000000 1.629606E-13 -3.038773E-09 2.05000E+01 -1.535787E-17 8.375897E-14 -1.485183E-10 8.501001E-02
PROSPER Manual
A0 8.776504E-06 -7.290256E-04 1.695927E-07
1.838891E-05
-4.764406E-07 -2.538143E-03 4.492726E-08
1.474800E-04
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2.15.4.6ESP MOTORS *Manufacturer Reda * Number of motors, rpm, frequency 2 3450. 60.0 *Series OD 456 4.56 *amps 6.53822E-01 -1.34128E+00 8.86349E-01 -1.06114E-01 5.61883E-01 3.43896E-01 * *rpm -6.24718E+01 2.04999E+02 -3.03911E+02 1.45552E+02 -1.15803E+02 3.58291E+03 * *efficiency -5.57129E-01 1.60591E+00 -7.30540E-01 -1.98693E+00 2.49918E+00 1.91886E03 * * power factor -5.44220E-01 2.16557E+00 -2.81504E+00 7.11957E-01 1.04810E+00 2.49609E01 * *Series OD 540 5.4 *amps -2.16508E-01 6.79101E-01 -5.79651E-01 3.59379E-01 5.24583E-01 2.26834E-01 * *rpm -2.14557E+01 8.55182E+01 -1.66122E+02 9.44086E+01 -1.44510E+02 3.58175E+03 * *efficiency 3.67150E-01 -1.64327E+00 3.01018E+00 -3.02514E+00 1.72215E+00 4.17187E01 * * power factor 4.64765E-01 -2.48102E+00 5.12024E+00 -5.23541E+00 2.71560E+00 2.75835E01 * *Series Type HP VOLTS AMPS 456 S 100.0 1075 51 © 1990-2011 Petroleum Experts Limited
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456 456 456 456 456 456 456 456 456 456
S S S S S S T T T T
100.0 100.0 110.0 120.0 120.0 120.0 200.0 220.0 240.0 240.0
1355 2205 1190 1255 1295 2245 2710 2380 2250 2590
46 29 60 70 59 35 46 60 70 59
540 540 540 540 540 540 540 540 540 540 540
S S S S S S T T T T T
180.0 180.0 200.0 200.0 225.0 225.0 450.0 480.0 480.0 540.0 600.0
945 120 1945 59 1100 115 2140 54 1135 127 2235 64 2270 127 2475 122 3345 89 2835 120 3300 115
2.15.4.7ESP CABLES * Cable Type * Volt drop coefficient Maximum ampage #1 Copper 0.26 115 #2 Copper 0.33 95 #4 Copper 0.53 70 #6 Copper 0.84 55 #8 Copper 1.32 50 #10 Copper 2.08 50 #12 Copper 3.32 50 #1 Aluminium 0.33 #2 Aluminium 0.53 PROSPER Manual
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#4 Aluminium 0.84 #6 Aluminium 1.32 #8 Aluminium 2.08 #10 Aluminium 3.32
626
55 50 50 50
2.15.4.8HSP PUMPS * * H Y D R A U L I C D R I V E D O W N H O L E P U M P S* ================= ========= =============== ========= * This is a sample pump import file. Blank lines or lines begining * with an asterisk are ignored. The format for the pump data is * Line 1 Manufacturer pumpname size (mm) reference Speed(rpm) Min. * operating rate Max. operating rate No. of stages Max no. of Stages Min * Speed Max Speed * Line 2 six coefficients for head curve (ft of water) (a0 to a5) * Line 3 six coefficients for power curve (HP) (a0 to a5) * This data is supplied FOR EXAMPLE PURPOSES ONLY ********** DO NOT USE FOR SYSTEM DESIGN * Contact the pump supplier for current performance data **************************** **************************** **************************** *** WEIR PUMPS *** **************************** **************************** ****************************
WEIR TPL115 118 11500 2000 12200 1 18 3825 11500 439.726 -0.0145605 1.7487e-7 -4.0609e-11 -1.2e-15 6.7794e-20 15.0445 0.00470131 -8.1656e-7 9.018e-11 -5.0595e-15 9.7463e-20
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2.15.4.9HSP TURBINES Turbine Manufacturer WEIR* Number of Turbines1***************** ** WEIR T30 ** ****************** Turbine TypeT30* Reference Speed (rpm) 15000.0 * Maximum Speed 15000.0
(rpm)
* Maximum Test Pressure 8910.00
(psi)
* Maximum Working Pressure 5940.00
(psi)
* Maximum Stage Pressure 370.00
(psi)
* Maximum Number Of Stages 50 * Maximum Turbine Supply Flow 3911.67 * Maximum Total Shaft Torque 843 * Maximum Stage Torque 128 * Turbine Casing OD 3.46
(bbl/day) (lb.ins) (lb.ins)
(inches)
* Max. Velocity Over Turbine Casing (ft/sec) 25.000 * Number of Settings 4 * Setting should be an alphanumeric string with NO embedded spaces (up to 8 characters) * Setting Efficiency Mininum Maximum Head Head Power Power * Rate Rate (a1) (a2) (a3) (a1) * (percent) (bbl/day) (bbl/day)
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A 52.750 1235.26 2038.18 0.000311733 -0.53145 447.209 2.2765e6 -0.00245738 0.551433 B 56.000 1523.49 2460.23 0.000146428 -0.163852 184.132 1.6612e6 -0.00126675 -0.431372 C 60.460 1873.48 3232.27 0.000116043 -0.281785 395.769 1.8284e-6 -0.0037038 2.46547 D 64.000 2367.59 3788.14 6.97987e-5 -0.150449 243.193 2.0903e6 -0.00670166 7.15005
2.15.5 E - Glossary Bottom Hole Pressure measured at the producing formation. pressure. Flowing Pressure
Intake node
A volume ratio that indicates the deviation of the actual volume from Compressibility that which has been determined by the Ideal Gas Laws. The Compressibility Factor is a multiplier Dew Point
The temperature at which the vapour will start to condense. Dew point of a gas mixture is the temperature at which the highest boiling point constituent will start to condense.
Dimensionless Fracture Conductivity (FCD)
Dimensionless fracture conductivity is a key design parameter in well stimulation that compares the capacity of the fracture to transmit fluids down the fracture and into the wellbore with the ability of the formation to deliver fluid into the fracture.
Dry Gas
Any gas or gas mixture which contains no water vapour, and where all of the constituents are substantially above their respective saturated vapour pressure at the existing conditions.
Energy
A substance's capacity, either latent or apparent, to exert a force through a distance.
Enthalpy
The sum of the internal and external energies. Enthalpy is defined as H = U + P*V where U is the energy of a system, P the pressure, and V the volume. At constant volume and temperature, the differential change in enthalpy as pressure and entropy S are varied is therefore dH = TdS + VdP
Entropy
A measure of the unavailable energy in a substance. The concept of entropy in thermodynamics is central to the second law of thermodynamics, which deals with physical processes and whether they occur spontaneously. Spontaneous changes occur with an increase in entropy. Spontaneous changes tend to smooth out differences in temperature, pressure, density, and chemical © 1990-2011 Petroleum Experts Limited
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potential that may exist in a system, and entropy is thus a measure of how far this smoothing-out process has progressed. Entropy change is defined as a change to a more disordered state at a molecular level. In recent years, entropy has been interpreted in terms of the "dispersal" of energy. Entropy is an extensive state function that accounts for the effects of irreversibility in thermodynamic systems. Quantitatively, entropy, symbolized by S, is defined by the differential quantity dS = δQ / T, where δQ is the amount of heat absorbed in a reversible process in which the system goes from one state to another, and T is the absolute temperature. Entropy is one of the factors that determines the free energy of the system. External Energy
The energy represented by the product of pressure and volume. It may be regarded as the energy a substance possesses by virtue of the space it occupies.
Formation Gas- Quantity of oil dissolved in 1 stock tank barrel of oil at prevailing pressure and temperature. Solution GOR. See GOR Definitions Oil Ratio Formation Volume occupied by 1 barrel of stock tank oil and its associated Volume Factor solution gas at a given pressure and temperature. (Bo) Gas Gravity
Ratio of the gas density to density of air. Equal to ratio of molecular weight to that of air (28.97).
Geothermal Gradient
Rate of increase in earth temperature with depth. One example: 1.8 degrees F per 100 feet of TVD.
GOR
When oil is brought to surface conditions it is usual for some gas to come out of solution. The gas/oil ratio (GOR) is the ratio of the volume of gas that comes out of solution, to the volume of oil. A point to check is whether the volume of oil is measured before or after the gas comes out of solution, since the oil volume will shrink when the gas comes out. In fact gas dissolution and oil volume shrinkage will happen at many stages during the path of the hydrocarbon stream from reservoir through the wellbore and processing plant to export. For light oils and rich gas condensates the ultimate GOR of export streams is strongly influenced by the efficiency with which the processing plant strips liquids from the gas phase. Reported GORs may be calculated from export volumes which may not be at standard conditions.Can refer to solution GOR or Total GOR (i.e. including free gas production). See GOR Definitions
Heat
The energy transferred because of a temperature difference. There is no transfer of mass.
Heat Transfer Coefficient describing the total resistance to heat loss from a producing pipe to its surroundings. Includes heat loss by Coefficient PROSPER Manual
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(HTC)
conduction, convection and radiation.
Holdup
(Liquid holdup). Proportion of pipe area occupied by liquid. Equal to 1.0 for single phase liquid and 0.0 for single phase gas.
Ideal Gas
A fictitious gas that obeys the equation of state PV=RT/m where V is specific volume, T is absolute temperature, R is the universal gas constant and m id the molecular weight. Real gases deviate from ideal behaviour at atmospheric pressures.
Inflow Performance Relationship (IPR)
The relation between reservoir pressure, flowing bottom hole pressure and production rate. Can be calculated from reservoir properties (reservoir pressure, permeability, skin) or fitting an empirical relation to measured pressures. See IPR Definition
Injection Gas
Gas injected into a reservoir for pressure maintenance. Not to be confused with gas lift injection.
Injectivity Index Slope of inflow performance relation for injection. Expressed as injection volume per unit of injection pressure. (BBL/psi, Sm3/Bar). Internal Energy The energy which a substance possesses because of the motion and configuration of its atoms, molecules and sub atomic particles. Isentropic Process (Adiabatic)
A process during which there is no heat added to or removed from the system.
Isothermal Process
A process during which there is no change in temperature.
JouleThomson Coefficient
The Joule-Thomson effect, or Joule-Kelvin effect, is a process in which the temperature of a real gas is either decreased or increased by letting the gas expand freely at constant enthalpy (which means that no heat is transferred to or from the gas, and no external work is extracted). It's named after James Prescott Joule and William Thomson, 1st Baron Kelvin who established the effect in 1852 following earlier work by Joule on Joule expansion in which a gas expands at constant internal energy. The relationship between temperature, pressure and volume of a gas is simply described by the various gas laws. When volume is increased in an irreversible process, the gas laws do not uniquely determine what happens to the pressure and temperature of the gas. Reversible adiabatic expansion, in which the gas does positive work in the process of expansion, always causes a decrease in temperature. However, when a real gas (as differentiated from an ideal gas) expands freely at constant enthalpy, the temperature may either decrease or increase, depending on the initial temperature and pressure. For any given pressure, a real gas has a Joule-Thomson (Kelvin) inversion temperature, above which expansion at constant enthalpy causes © 1990-2011 Petroleum Experts Limited
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the temperature to rise, and below which expansion at constant enthalpy causes cooling. For most gases at atmospheric pressure, the inversion temperature is fairly high (above room temperature), and so most gases at those temperature and pressure conditions are cooled by isenthalpic expansion. The change of temperature with respect to a change of pressure in a Joule-Thomson process is the Joule-Thomson (Kelvin) coefficient
Definition of the Joule-Thom son Coefficient
The value of µ depends on the specific gas, as well as the temperature and pressure of the gas before expansion. For all real gases, it will equal zero at some point called the inversion point and the Joule-Thomson inversion temperature is the temperature where the coefficient changes sign (i.e., where the coefficient equals zero). In any gas expansion, the gas pressure decreases and thus the sign of dP is always negative. The following table explains when the Joule-Thomson effect cools or heats a real gas If the gas then µ is since d P is d T must be so the gas temperatur e is below the always positive negative cools inversion negative temperature
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above the inversion temperature
negative
always negative
positive
632
heats
It should be noted that µ is always equal to zero for ideal gases (i.e., they will neither heat nor cool upon being expanded at constant enthalpy). Kinetic Energy The energy a substance possesses by virtue of its motion or velocity. Measured Depth
Depth measured along the flow path from the depth reference to a point in the well.
Node
A reference point in the well. A calculation node is inserted whenever there is a change of I.D., deviation angle or temperature gradient.
Partial Pressure
The absolute pressure exerted by a constituent portion of the mixture.
Permeability
Permeability (commonly symbolized as κ, or k) is a measure of the ability of a material (typically, a rock or unconsolidated material) to transmit fluids. It is of great importance in determining the flow characteristics of hydrocarbons in oil and gas reservoirs. The intrinsic permeability of any porous material is: k = C * d2 where k is the intrinsic permeability C is a dimensionless constant that is related to the configuration of the flow-paths d is the average, or effective pore diameter Permeability needs to be measured, either directly (using Darcy's law) or through estimation using empirically derived formulas. A common unit for permeability is the darcy (D), or more commonly the millidarcy (mD) (1 darcy @10- 12m²). Other units are cm² and the SI m2. Permeability is part of the proportionality constant in Darcy's law which relates discharge (flow rate) and fluid physical properties (e. g. viscosity), to a pressure gradient applied to the porous media. The proportionality constant specifically for the flow of water through a porous media is the hydraulic conductivity; permeability is a portion of this, and is a property of the porous media only, not the fluid. In naturally occurring materials, it ranges over many orders of magnitude. For a rock to be considered as an exploitable hydrocarbon reservoir, its permeability must be greater than approximately 100 mD (depending on the nature of the hydrocarbon - gas reservoirs with lower permeabilities are still exploitable because of the lower viscosity of gas with respect to oil). Rocks with © 1990-2011 Petroleum Experts Limited
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permeabilities significantly lower than 100 mD can form efficient seals. Unconsolidated sands may have permeabilities of over 5000 mD. Phase
A homogeneous body of material which differs in its intensive properties from that of its neighboring phases. e.g. Gas, liquid.
Potential Energy
The energy a substance possesses because of its elevation above the earth or above some chosen datum plane.
Pressure Traverse
Calculation of well pressure vs depth by integrating the pressure gradient for increments of pipe.
Produced Gas/ Gas production divided by oil production. Includes gas in solution and any free gas production. Excludes lift gas returned to surface Oil Ratio with the produced fluids. Productivity Index (PI)
Measure of a well's ability to flow. Expressed in bbl/psi (Sm3/day / Bar) of drawdown. Applies above the bubble point.
Pseudo-Critical The Critical Temperature is defined as the highest temperature at which a gas can be liquefied. When calculated for a mixture it is Temperature called the Pseudo-Critical Temperature. The Critical Pressure of a gas is defined as the saturation Pseudo-Critical pressure at the Critical Temperature. It is the highest vapour pressure the liquid can exert. Critical conditions must be Pressure determined experimentally for each gas. When calculated for a mixture, it is called the Pseudo-Critical Pressure. Quality
Weight percent of vapour present in a two-phase mixture.
Reduced Pressure
The ratio in absolute units of the actual gas pressure to the critical pressure of the gas.
Reduced temperature
The ratio in absolute units of the actual gas temperature to the critical temperature of the gas.
Reservoir
Accumulation of hydrocarbon in permeable rock.
Residual Oil
Liquid remaining in a PVT cell at the completion of a differential liberation experiment.
Retrograde Condensate
Hydrocarbon existing as a gas at reservoir conditions from which liquid drops out as the pressure drops. The liquid may evaporate as the pressure drops further.
Saturated Oil
Oil in equilibrium with its vapour at a specified temperature and pressure.
Saturated Vapour Pressure
The pressure existing at a given temperature in a closed volume containing a liquid and a vapour from that liquid after equilibrium conditions have been reached. It is dependent only on temperature and must be determined experimentally.
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Saturation Pressure
Pressure at which vapor and liquid are in equilibrium. For oils, equivalent to bubble point.. For condensates, the dew point.
Shrinkage
Decrease in volume of oil from reservoir conditions to the stock tank. Shrinkage occurs as oil gives up solution gas and temperature drops.
Shrinkage Factor
Reciprocal of Formation Volume Factor.
Solution Gas
Gas dissolved in oil at elevated pressure and temperature.
Solution Gas Volume of gas dissolved in stock tank unit of oil at saturation pressure (scf/STB, Sm3/Sm3). See GOR Definitions Oil Ratio (Rs) Specific Gravity Ratio of fluid density to that of water at 60 degrees F. For gases, ratio of gas density to that of air at standard conditions. (Liquid) Ratio of the density of a given gas to the density of dry air, both Specific Gravity measured at the same specific conditions of pressure and (Gas) temperature. These conditions are usually 14.696 psiA and 60ºF, or 1 barA and 0ºC. Specific or Capacity
Heat The rate of change in enthalpy with temperature. It may be Heat measured at constant pressure or at constant volume. The values are different and are known as Cp and Cv, respectively.
Specific Volume
The volume of a given weight of gas usually expressed as cubic feet per pound, or cubic meters per kilogram (cubic centimeters per gram).
Static Reservoir Pressure
Stabilised reservoir pressure if all wells were shut in and built up.
STB
Stock Tank Barrel.
Steady-State
A state of the system in which none of the variables (such as pressure, temperature, flow rates) varies with time.
Stock Tank Oil
Oil in equilibrium with its surrounding conditions of temperature and pressure.
Temperature
The property of a substance which gauges the potential or driving force for the flow of heat.
True Depth
Vertical Vertical displacement from reference depth to a point in a well.
Under Saturated Oil
Oil capable of dissolving additional gas at a specified temperature and pressure. i.e current pressure is above the fluid's bubble point.
Empirical inflow performance relation that accounts for reduced oil Vogel Equation permeability when producing below bubble point due to gas breakout. © 1990-2011 Petroleum Experts Limited
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Water Cut
Ratio of water production to total fluid production. (Water Rate) / (Oil Rate + Water Rate)
Water Volume occupied at prevailing pressure and temperature by 1 stock tank unit of water. Formation Volume Factor (Bw) Water / Oil Ratio of oil production to water production (stock tank conditions) Ratio (WOR) Wet Gas
Any gas or gas mixture in which one or more of the constituents is at its saturated vapour pressure. The constituent at saturation pressure may or may not be water vapour.
Work
The energy transition and defined as force times distance. Work cannot be done unless there is motion.
2.15.6 F - Importing Data from Text Files This Section describes how to Import Data from a text file to a PROSPER model. It is assumed that the data to be imported is saved in a text file. It is also assumed that the data is imported for the tables in PVT section of PROSPER. The technique can however be applied at any place where data import is required to be done. 1) After clicking on the ‘Import’ tab, select the particular text file where the data is saved on screen 2) below.
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2) 3) When the import file is selected, press Continue to see the next screen (4) shown below.
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5) Select the particular File format in which the data is saved. The following example is for a Comma Separated format. Press Continue to see the next screen (7) below. 6)
7) 8) To select a particular column for a Field Name, one can directly click on the column and this will assign that column to that field.This can also be checked by the column number that is appended to the field name. 9) Make sure that the units for each column are correctly selected according to the input data. 10) The procedure can be repeated for all the columns. 11)
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12) By selecting continue, PROSPER will update the data in the corresponding columns in the tables. 13)
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3
Examples Guide
3.1
Prosper Tutorials This chapter contains a collection of tutorials designed to help jump-start the use of PROSPER. The tutorials are grouped by subjects: Integrated well bore models · Basic Tutorials for naturally flowing wells, · Sand control tutorials · Compositional modelling tutorials · Well test matching tutorials · Artificial lift design tutorials · Tutorials about trouble-shooting artificially lifted wells · Tutorials on pipeline modeling and flow assurance studies. · Tutorials on special topics Integrated well bore models Tutorial 00
Description Integrated oil well model
Reference File T00_IntegratedOilWell.OUT
Basic tutorials for naturally flowing wells Tutorial 01 02 03 04 05 07 08 09 10 11
Description Reference File Modelling a dry and wet gas producer T01_DryAndWetGasWell.Out T02_SimpleOilWell.OUT Modelling a naturally flowing oil well Modelling an oil well with black oil PVTT03_OilWellPVTMatching.OUT matching T04_HorizontalOilWell.out Modelling an horizontal oil well Modelling a multilateral dry gas producer T05_MultilateralGasWell.Out T07_SlantedOilWell.Out Modelling a slanted oil well Modelling a gas well with connected T08_GasWellwithSurfacePipeline. Out pipeline T09_WaterInjectionWell.OUT Modelling a water injection well T10_GasInjectionWell.OUT Modelling a gas injection well T11_SteamInjectionWell.OUT Modelling a steam injection well
Sand Control tutorials Tutorial 12 PROSPER Manual
Description Modelling an oil well with gravel-pack
Reference File T12_GravelPackedOilWell.OUT May, 2011
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T13_Frac&PackedOilWell.OUT T14_OilWellwithPrePackedScreen.out T15_OilWellwithslottedLiner.OUT Modelling a well with slotted liners Modelling a well with wire-wrapped T16_OilWellwithWireWrappedScre ens.out screens
Modelling a frac and pack well Modelling a well with pre-packed screen
Compositional modelling tutorials Tutorial 17 18
Description Reference File Fully compositional retrograde T17_CompostionalCondensateWell. Out condensate well T18_CompostionalCO2Injector.Out Fully compositional CO2 injection well
Well test matching tutorials Tutorial 19 20 21
Description Matching a gas well test Matching a naturally flowing oil well test Matching a water injection well test
22
Matching a gas injection well test
Reference File T19_MatchingAGasWellTest.OUT T20_MatchingAnOilWellTest.OUT T21_MatchingAWaterInjectionWellT est.OUT T22_MatchingAGasInjectionWellTes t.OUT
Artificial lift design tutorials Tutorial 23 24 25 26 27 28 29 30 31 43
Description Continuous Gas lift design Intermittent Gas Lift Design
Reference File
T23_ContinuousGasLiftDesign.OUT T24_IntermittentGasLiftDesign. OUT T25_CoiledTubingGasLiftDesign. Coiled Tubing Gas lift Design OUT Design of an ESP system for an oilT26_ESPDesign.OUT
producer Design of an HSP system for an oilT27_HSPDesign.OUT producer Design of a Sucker Rod Pump for an oilT28_SuckerRodPumpDesign.OUT producer Design of a PCP lift system for an oilT29_PCPDesign.OUT producer T30_DiluentInjection.OUT Diluent Injection tutorial Multiphase pump in a pipe connected to a T31_MultiphasePumpOnseabed. OUT single well Design of a Jet Pump system for an oilT43_JETPUMP.OUT producer © 1990-2011 Petroleum Experts Limited
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Tutorials about trouble-shooting artificially lifted wells Tutorial 32 33 34 35
Description Troubleshooting a gas lifted well Trouble-shooting an ESP-lifted well Trouble-shooting an HSP-lifted well Trouble-shooting a sucker rod lifted well
Reference File T32_GasLiftQuickLook.OUT T33_ESPQuicklook.OUT T34_HSPQuicklook.OUT No reference file
Pipeline and flow assurance study tutorials Tutorial 36 37 38 39
Description General flow assurance features Pipeline performance matching Full enthalpy balance example Improved approximation tutorial
Reference File T36_FlowAssurance.OUT T37_PipelineMatching.OUT T38_EnthalpyBalance.OUT T39_ImprovedApproximation.OUT
Special topics Tutorial 40 41 42 44
Description Reference File T40_SPOT.OUT SPOT example Multi-layer model with dP loss between the T41_MultilayerOil.Out zones Multilateral IPR for well penetrating T42_MultiLateralInMultipleReservo different zones irs.OUT Validation of the black oil PVT model for T44_CONDVALID.OUT
gas retrograde condensate producer
3.1.1 Tutorial 00: Integrated Oil Well Model File: ~/samples/PROSPER/T00_IntegratedOilWell.OUT This integrated well modeling tutorial combines existing data with consistent engineering assumptions to develop a solid well bore model using PROSPER. The developed well bore model is then used to simulate the performance of the well under possible future operating conditions with different GOR, water cut and reservoir pressure. For this, sensitivity runs are performed with different GOR, water cut and reservoir pressure. The approach can be easily extended to any other possible sensitivity variable: tubing size, skin, permeability, thickness and so on. 3.1.1.1 Objectives This tutorial demonstrates how to analyse the performance of an offshore oil producing well in an integrated fashion. In the process, the following questions are addressed: - What are the basic data required to build a PROSPER model for a naturally flowing oil PROSPER Manual
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well, - How to match a black oil PVT against black oil correlations, - How to tune the overall heat transfer coefficient in the surroundings of a well based upon well test data - How to quality-check raw well test data, - Why and how to perform a correlation comparison, - How to perform a Verrtical Lift Perfoamnce (VLP) matching, - How to select a VLP correlation, - How to model a highly deviated well, - How to calibrate the well inflow with the well test data, - How to validate a PROSPER well model against actual well test data, - How to match multiple well tests, - How to use the calibrated PROSPER model to predict the future performance of a given well bore. 3.1.1.2 Statement of the Problem A naturally flowing highly deviated oil producing well has been drilled and tested. Extensive fluid and well test data are available. It is required to develop a PROSPER model that is calibrated against PVT lab data and well test data. Once the model is built and calibrated, it will be used for sensitivity run. 3.1.1.3 General Approach In this tutorial, the following road map will be followed: a. Construct a PROSPER well model with a matched and validated PVT model b. Analyse and match the well test data against the PROSPER model to obtain a calibrated well bore model c. Use the calibrated well bore model to simulate the performance of the well under changing conditions: water cut, GOR and reservoir pressure. 3.1.1.4 Available Data & Information The data required for a well test analysis are: -
PVT data Reservoir Data Well Data: deviation survey, tubing, casing, and temperature data Actual production test data: stabilized phase rates, flowing temperatures and pressures.
About PVT data When building a PROSPER well model, there are in general two possible situations to consider with respect to the PVT data. There can be a situation where enough PVT data are available. The second contrasting situation arise when there is © 1990-2011 Petroleum Experts Limited
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very little PVT data available. If comprehensive black oil PVT data are available, then it is recommended to match the PVT data to the black oil correlations. The advantages of matching the black oil data to correlations are: - The PVT matching process offers an opportunity to check the quality of the PVT data themselves by analyzing the magnitude of the correction required to reproduce the various PVT data: GOR, Oil FVF, Bubble point pressure and oil viscosity. - At the end of the PVT matching process, the most suitable black oil correlation for the particular crude is selected and used for further calculations. - Unlike PVT look-up tables, carefully matched black oil correlations may generally be used for operating conditions beyond the values used for the PVT matching. In the event no extensive PVT data or no reliable PVT data are available, the black oil correlation may generally be used directly without any matching to start with. The selection of the appropriate black oil correlation is a matter of engineering judgment that is at the discretion of the project engineer. For details about the published validity range of each black oil correlation in PROSPER, the relevant references listed in the appendix A of this manual may be consulted. It is strongly recommended to match the black oil correlations against lab measurements as soon as a PVT report becomes available. About Reservoir data The purpose of each specific study determines the type of reservoir model to be selected and consequently the parameters required. In the absence of typical reservoir properties like permeability, net pay, skin and so on, the simple Productivity Index (PI entry ) or its equivalent for gas (C & n) may be used. If extensive reservoir and skin parameters are available, then an alternative inflow model that better fits the purpose of the study is to be considered. About well equipment data The well equipment data like deviation survey, surface equipment, down hole equipment and geothermal gradient are generally available from well bore schematic and temperature logs. The overall heat transfer coefficient in the surroundings of the well bore can be either computed with the enthalpy balance model or derived from well test data. When the rough approximation method is being used, the following overall heat transfer coefficients values may be considered as starting values: For oil and water wells: 8 Btu/h/ft2/F. PROSPER Manual
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For retrograde condensate wells: 5 Btu/h/ft2/F. For gas wells: 3 Btu/h/ft2/F. It is recommended to fine-tune the overall heat transfer coefficient with well test data as soon as well test are available. It is recommended to keep the default average heat capacities displayed in the program under | System | Equipment | Average Heat Capacities unaltered. About well test data Well test data are generally used to: - back-calculate the overall heat transfer coefficient in the surroundings of the well when the rough approximation temperature method is selected. - select the multiphase correlation most suitable for the particular well model - fine-tune the inflow performance parameters like reservoir pressure, skin, permeability and so on. Note that it is perfectly possible to develop a PROSPER model in the absence of well test data. In this case, reasonable assumptions are to be made based upon the specific operating conditions of the well and based upon existing relevant experiences. Generally, the use of the Petroleum Experts 2 multiphase correlation may be considered when no well test data are available for the simple reason that the Petroleum Experts 2 multiphase correlation has so far consistently given reasonable results in very diverse operating conditions. However, since there is no universal multiphase correlation, it is recommended to verify the suitability of the selected multiphase correlation (Petroleum Experts 2) as soon as well test data become available. PROSPER offers a coherent and consistent VLP matching procedure that helps the user to select the most suitable correlation for any particular well. This consistent VLP matching procedure will be described and applied later in this tutorial in the sub-section "Well Test Analysis: Step by Step Procedure". 3.1.1.4.1 PVT Data from the lab The following fluid properties are available from the lab. Surface Data Solution GOR:
700 scf/stb
Oil Gravity:
35 API
Gas specific Gravity:
0.75 (Air =1)
Water Salinity:
120 000 ppm
Impurities (C02, N2, H2S):
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Down hole data Reservoir temperature: Bubble Point Pressure Temperature:
260 degF at Reservoir 3400 psig
Black Oil Properties in tabular format at a reference temperature of 260 degF Pressure in psig
GOR in scf/stb
Oil FVF in rb/stb
Oil Viscosity centipoises
2000
367
1.232
0.434
2500
477
1.289
0.383
3000
597
1.352
0.337
3400
700
1.408
0.306
3500
700
1.405
0.308
4000
700
1.395
0.320
4500
700
1.386
0.331
in
Note that the fluid properties may originate from a thermodynamic simulation (Constant Mass Expansion with separator correction) using a compositional fluid calibration package like PVTp. 3.1.1.4.2 Well Equipment Data (Tubing etc) Deviation survey
Measured Depth True Vertical Comment in ft Depth in ft 0
0
This is the origin of the deviation survey.
1500
1500
sea floor
2516
2500
4112
4000
5845
5500
7800
7000
10135
8500
11135
9000
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The deviation survey is the reference for all subsequent depths inputs in the equipment section. Surface Equipment This well model will not include pipelines downstream of the well head. Down hole Equipment
Label
Equipment Type
Measured Depth in ft
Inside Diameter inches
Roughness in in inches
Well Head
Xmas Tree
0
N/A
0.0006
Tubing
Tubing
2000
3.92
0.0006
Safety Valve
SSSV*
N/A
3.5
0.0006
Tubing
Tubing
10800
3.92
0.0006
Casing
Casing
11135
6.4
0.0006
*A Sub Surface Safety Valve is treated as a restriction without length. Note that the deepest entry of 11135 ft measured depth ( = 9000 ft TVD) in the down hole equipment is the datum depth for the reservoir pressure when a single layer inflow model is used in PROSPER. Geothermal Gradient
Measured depth in ft
formation Static temperature
ambient Comment
0
60
well head depth
1500
45
sea floor
11135
260
Reservoir depth
Starting value for the overall heat transfer coefficient: 8 Btu/h/ft2/F. Average Heat Capacities The default average heat capacity values will be used.
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3.1.1.4.3 Inflow Performance Data The well penetrates the reservoir at an angle of 60 degrees. This is therefore a slanted / deviated well. There are other options that can be used to model deviated wells in PROSPER: CincoLey and Multilateral IPR. In this tutorial, the Wong-Clifford model will be used for the calculation of deviation and partial penetration skin.
Reservoir model:
Darcy
Mechanical Geometrical Skin model:
Enter Skin By Hand
Deviation and Partial Penetration Skin model:
Wong-Clifford*
Static Reservoir Pressure at datum (11135 ft MD):
4000 psig
Static Reservoir Temperature at datum:
260 degF
Water Cut:
25%
Total GOR:
700 scf/stb
Compaction Permeability Reduction Model:
No
Relative Permeability:
No
Reservoir Permeability:
100 mD
Reservoir Thickness:
100 ft
Drainage area:
350 acres
Dietz shape factor:
31.6
Well bore Radius:
0.354 ft
Mechanical skin:
0
Enable Wong-Clifford:
ON
Formation Vertical Permeability Ratio:
0.1 (fraction)
Local Vertical Permeability Ratio:
0.1 (fraction)
Horizontal Distance from Well to Reservoir Edge:
2200 ft
Depth of Top Reservoir (TVD):
9000 ft
*Perforation start in measured depth:
11135 ft
*Perforation start in true vertical depth:
9000 ft
*Perforation end in measured depth:
11427
*Perforation end in true vertical depth:
9100 ft
*Using the Wong-Clifford skin model, the deviation angle of the well well bore across the reservoir is calculated based upon the user-entered perforation intervals in PROSPER Manual
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measured depth and true vertical depth. 3.1.1.4.4 Multi-Rate Well Test Data The reported well test results are listed below: Static Reservoir Pressure at Datum (9000 ft TVD): 4000 psig Gauge depth: 10500 ft measured depth Dates
Comm WH ent FP
WHFT Water Cut
Liquid Rate
Gauge Pressure at Gas Oil gauge depth Ratio
dd/mm/ yyyy
psig degF
%
stb/d
psig
scf/stb
01/01/2 Low 000 Rate
1000 150
25
6100
3655
1500
02/01/2 Medium 800 000 Rate
180
25
9800
3505
500
03/01/2 High 000 Rate
200
25
13450
3365
475
500
3.1.1.5 Model Construction: Step by Step Procedure Options Launch PROSPER, select | Options | Options and make the following choices:
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Select | Done to complete this. PVT input Data Select | PVT | Input Data and populate the PVT entry screen as follow: Surface Data Solution GOR:
700 scf/stb
Oil Gravity:
35 API
Gas specific Gravity:
0.75 (Air =1)
Water Salinity:
120 000 ppm
Impurities (C02, N2, H2S):
None
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In order to enter the lab data, select | Match Data and populate the screen as shown below:
Reservoir temperature: Bubble Point Pressure Temperature:
260 degF at Reservoir 3400 psig
Black Oil Properties in tabular format @ a reference temperature of 260 degF Pressure in psig
GOR in scf/stb
Oil FVF in rb/stb
Oil Viscosity centipoises
2000
367
1.232
0.434
2500
477
1.289
0.383
3000
597
1.352
0.337
3400
700
1.408
0.306
in
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3500
700
1.405
0.308
4000
700
1.395
0.320
4500
700
1.386
0.331
Select | Done to return to the previous menu PVT matching For the PVT matching, select | Regression | Match All | OK | Parameters and this is what can be seen:
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This screen shows the values of the Match Parameters (Parameter 1= multiplier and Parameter 2 = shift) associated with each fluid property for all the correlations. The Standard Deviation is also displayed which represents the overall goodness of fit. Select an appropriate correlation bearing in mind that the black oil correlations whose parameters are adjusted the least (i.e. Parameter 1 close to 1.0 and Parameter 2 close to 0.0) are the most suitable candidates as they represent possibly similar fluids to the one being modelled. The value of the Standard Deviation is also displayed. Generally, the lower the Standard Deviation, the better the fit. In the case at hand, the combination Glaso / Beal et al will be selected because they require the least adjustment. For this, select | Done | Done and make sure that the black oil correlations Glaso / Beal have been selected on the PVT- Input Data screen:
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Select | Done and save the file to secure the data inputted into the PROSPER well bore model.
Well Equipment Data
Select | System | Equipment (Tubing etc) | All | Edit to start the well bore description with the deviation survey: Deviation survey
Measured Depth True Vertical Comment in ft Depth in ft 0
0
This is the origin of the deviation survey.
1500
1500
sea floor
2516
2500
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4000
5845
5500
7800
7000
10135
8500
11135
9000
656
Top of perforation
The deviation survey is the reference for all subsequent depths inputs in the equipment section.
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Select | Done to proceed with the surface equipment data Surface Equipment This well model will not include pipelines downstream of the well head. Therefore select | Cancel to skip this screen:
Down hole Equipment
Label
Equipment Type
Measured Depth in ft
Inside Diameter inches
Well Head
Xmas Tree
0
N/A
0.0006
Tubing
Tubing
2000
3.92
0.0006
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SSSV*
N/A
3.5
0.0006
Tubing
Tubing
10800
3.92
0.0006
Casing
Casing
11135
6.4
0.0006
658
*A Sub Surface Safety Valve is treated as restriction without length.
Simply point the cursor on the relevant cell within the column labeled "Type" underneath the "Xmas Tree" to select the equipment type from a drop-down menu: tubing, SSSV, Restriction or casing. Labels are optional. Select | Done to enter the geothermal gradient Geothermal Gradient
Measured depth in ft
formation Static temperature
ambient Comment
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0
60
well head depth
1500
45
sea floor
11135
260
Reservoir depth
Starting value for the overall heat transfer coefficient: 8 Btu/h/ft2/F.
Select | Done to continue with the data inputs. Average Heat Capacities The default average heat capacity values will be used.
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Select | Done to complete the description of the well bore schematic. Visualizing the well bore sketch
To visualize the well bore sketch, select | Summary | Draw Down Hole and the next sketch is generated:
Select | Main and | File | Save to secures all changes made. Inflow Performance - Model selection © 1990-2011 Petroleum Experts Limited
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For the selection of the inflow performance model, select | System | Inflow Performance and make the following choices:
Reservoir model:
Darcy
Mechanical Geometrical Skin model:
Enter Skin By Hand
Deviation and Partial Penetration Skin model:
Wong-Clifford
Static Reservoir Pressure at datum (11135 ft MD):
4000 psig
Static Reservoir Temperature at datum:
260 degF
Water Cut:
25%
Total GOR:
700 scf/stb
Compaction Permeability Reduction Model:
No
Relative Permeability:
No
Select the Input Data Tab in the top right corner to continue with the reservoir data PROSPER Manual
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inputs: Reservoir Permeability:
100 mD
Reservoir Thickness:
100 ft
Drainage area:
350 acres
Dietz shape factor:
31.6
Well bore Radius:
0.354 ft
Select the | Mech / Geom Skin tab at the bottom of the screen to proceed with the skin data entry:
Mechanical skin:
0
Enable Wong-Clifford:
ON
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Note that the option "Enable Wong-Clifford" model needs to be ticked! Select the next tab "Dev / PP Skin" at the bottom of the screen to enter the parameters required to computed the deviation and partial skin using the Wong-Clifford method: Formation Vertical Permeability Ratio:
0.1 (fraction)
Local Vertical Permeability Ratio:
0.1 (fraction)
Horizontal Distance from Well to Reservoir Edge:
2200 ft
Depth of Top Reservoir (TVD):
9000 ft
*Perforation start in measured depth:
11135 ft
*Perforation start in true vertical depth:
9000 ft
*Perforation end in measured depth:
11427
*Perforation end in true vertical depth:
9100 ft
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In order to generate an Inflow curve, simply select | Calculate and the following IPR curve is generated:
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Select | Main and save the PROSPER file. This completes the construction of the model. 3.1.1.6 Well Test Analysis: Step by Step In order to achieve a successful well test matching, it is important to follow a consistent and reproducible path. In the following pages a consistent step-by-step well test matching procedure is described and applied in order to construct a validated and calibrated PROSPER well bore model. The procedure can be broken down into the following steps: - Critical review of the raw well test data - Well test data entry in PROSPER - Estimate the overall heat transfer coefficient in the well bore surroundings - Perform a correlation comparison - Select and Match VLP correlation - Quality-check VLP matching by inspecting the matching parameters and re-performing correlation comparison for validation - Superimpose and match the well inflow performance relation curve. Step 1: Critical review of the raw well test data Well test matching is a process of reconciliation between a mathematical model ( PROSPER Manual
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PROSPER well bore model) and actual measurements. The reconciliation process can only be successful if the mathematical model and the actual measurements are both reliable. The various sequences followed so far to construct the PROSPER model have been specifically designed to lead to a reliable, sound PROSPER well bore model. The main purpose of the critical review of the raw well test data is to assess the validity of each well test data before entering them into PROSPER. A few of the questions to be addressed in the critical data review process are: - How reliable is each reported measurement? - How do the test data compare with historical trends? - How does the produced GOR compares with the PVT model? Let us critically review the well test data to be analysed in this tutorial:
Dates
Comm WHF WHF Water Liquid ent P T Cut Rate
dd/mm/ yyyy
psig
degF %
01/01/20 Low 00 Rate
1000 150
Gauge Gas Oil Ratio Pressure at gauge depth
stb/d
psig
scf/stb
25
6100
3655
1500
02/01/20 Medium 800 00 Rate
180
25
9800
3505
500
03/01/20 High 00 Rate
200
25
13450
3365
475
500
On can notice that: - The flow rate decreases as the well head pressure increases. This trend generally makes sense. - Equally, the gauge pressure increases as the flow rates decreases. This trend generally makes sense. - However, the reported GOR is not constant even though the reservoir is still undersaturated. This does not make sense and needs to be taken into consideration during the analysis. Step 2: Well Test Data entry into PROSPER In order to enter the well test data, select | Matching | Matching | VLP/IPR (Quality Check).
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Afterward populate the VLP/IPR matching screen as shown below:
Step 3: Estimate the overall heat transfer coefficient When analyzing multiple well tests, it is good practice to estimate the U-value for each PROSPER Manual
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test and see if there are severe deviations or not. For, this select the task button "Estimate U Value" and the following sub-screen is shown:
One shall keep in mind that: - the model was built with a starting U-value of 8 Btu/h/ft2/F - the estimated U value depends upon test mass flow rates and well head flowing pressure. Therefore a GOR suspected to be inconsistent will affect the total mass and consequently adversely impact the estimated U value. Therefore the estimated U-values at this stage will not be transferred to the geothermal gradient screen as input value. Step 4: Perform correlation comparisons The purposes of the correlation comparison are: - to check if the well test is valid, e. g. if the gauge pressure lies between FancherBrown and Duns & Ros modifed and - to identify which correlation best reproduces the well test results. Correlation Comparison for the "Low Rate" test: For this, simply select the test by clicking on the corresponding row number.
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Afterwards, select | Correlation Comparison | OK and then select the correlations Duns and Ros Original, Fancher-Brown, Petroleum Experts 2 and Petroleum Experts 5 for instance:
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Proceed with | Calculate | Calculate | OK | Plot and the following plot is shown:
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One can see that the test point is completely outside established physical boundaries. The physical boundaries are defined by the Fancher-Brown correlation that neglects slippage effects between the phases and consequently under-estimate the pressure loss and the Duns and Ros Modified correlation that generally over-estimates pressure drops in oil wells. During the critical review of the well test data, it was suspected that the reported GOR values were inconsistent. Indeed, with a bubble point pressure of 3400 psig and a reservoir pressure of 4000 psig, the produced GOR must be equal to the solution GOR of 700 scf/stb. Therefore we will go back and correct all GOR values to 700 scf/stb as show below:
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After correcting the GOR, one can now re-estimate the U-value for each test. For this simply select | Estimate U-value and the algorithm will estimate and display the U value for each test. In the end, the average U-value is calculate and displayed:
We will select | Yes and | OK to transfer the averaged U-value for all 3 tests to the geothermal gradient screen. Based upon engineering judgment, one may very well not accept the averaged U-value and use an alternative one. Here are the correlation comparison plots obtained for each test: Correlation Comparison for the Low Rate Test
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Correlation Comparison for the Medium Rate Test
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Correlation Comparison for the High Rate Test
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It can be observed that the Petroleum Experts 2 correlation consistently reproduces each well test with reasonable accuracy. Step 5: Select and Match VLP correlation (s) Because the Petroleum Experts 2 correlation consistently reproduces each well test with reasonable accuracy, this particular correlation will be selected for further analysis. It is possible to match multiple well tests simultaneously in PROSPER. For this, one simply need to keep all well tests enabled and the VLP matching algorithm will attempt to match all enabled well tests simultaneously. In the following, a better approach is applied: match one test and verify how the match performs against non-matched well tests.
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For this, return to the VLP/IPR matching screen, select the most reliable well test. The choice of the most reliable well test is a matter of judgment that depends upon all the circumstances surrounding the test. In this example, it will be assumed that the well test with the highest flow rate is the more stable for the simple reason that it is more likely to be stable, to be in the friction dominated region of the tubing performance curve. To perform the match, select the "High Rate" well test (here on row number 3) and then select | Match VLP as highlighted in the screen-shot below:
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If no specific well test is selected, the VLP matching algorithm in PROSPER will match all well tests simultaneously. A possible drawback of this approach is that possibly invalid well tests may not be easily detected. A generally better approach is to: - select the most reliable well test - match this single well test. An appropriately matched VLP correlation is selected - verify if the remaining well tests can be reasonably reproduced with the selected VLP correlation. The advantages of this approach are: - suspicious / inconsistent well test can be detected - the selected VLP correlation is validated against historical well tests. Now select | Match | OK
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Note that the VLP correlation "Petroleum Experts 2" appears now appended with two numbers: gravity multiplier and friction multiplier. Both numbers are equal to unity suggesting that virtually no correction was required to match the well test. Now select | Done to return to the previous screen. Step 6: Quality-check VLP matching results To benchmark the VLP matching against the two other well tests, simply enable them and then perform correlation comparisons for each well test in turn. For this, enable the well tests, select each well test and then select | Correlation Comparison | Ok | Calculate | Calculate | Plot. This is how the correlation comparison looks like for the "Low Rate Test":
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And this is how the correlation comparison looks like for the "Medium Rate Test":
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In both cases, one can see that the matched correlation reproduces very well the other well tests. This fact validates the suitability of the correlation for use in predictive mode. Step 7: Super-impose and match well IPR In order to superimpose the IPR, return back to the VLP/IPR matching screen and then select the task button VLP/IPR.
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To initiate the calculation, select | Calculate:
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Please confirm the completion of the Calculation with | OK and the the screen is populated with calculation results as shown below:
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For each well test, actual test rate and simulated (solution) test rate are calculated and displayed in th bottom right corner of the screen. A graphical plot is generated when the button Plot is selected:
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The plot above shows for each well test, the IPR, the VLP the test point and the simulated solution. In the right corner of the screen, one can see the statistical comparison between measured test rate and test bottom hole flowing pressure versus simulated rates and pressures. The largest error is less than 2% and can be considered as acceptable. Now one can select | Main | File | Save to update the PROSPER model.
3.1.1.7 Sensitivity Runs It is required to predict the performance of the well under different conditions for water cut, GOR, reservoir pressure and reservoir pressure: Parameters:
Values
Well head flowing pressure (psig):
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GOR (scf/stb):
700
Water Cut (%):
20, 25, 30, 35, 40, 45, 50, 55, 60
Reservoir Pressure (psig):
4000, 3500
In order to perform the sensitivity runs, select | Calculation | System (Ipr + Vlp) | 3 Variables and make the following entries:
Select | Continue and choose the relevant sensitivity variables water cut and reservoir pressure using the drop down menu:
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Select | Continue | Calculate | OK | Plot | System Plot and the following graphical representation is generated:
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The results can also be represented in an alternative graphical fashion: as sensitivity plot. For this select | Finish | Sensitivity | Variables and here select for instance liquid rate as function of water cut:
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By selecting | done, the following plot is generated:
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This plot shows the liquid rate as function of water cut for different reservoir pressures. This completes this tutorial.
3.1.2 Tutorial 01: Modelling a dry and wet gas producer File: ~/samples/PROSPER/T01_DryAndWetGasWell.OUT The main objectives of this example are to show: · How to set up a PROSPER model for a dry and wet gas well, · How to enter basic black oil PVT data, · How to enter the IPR data, · How to describe the down hole equipment, · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP, · How to generate a well performance curve, · How to generate and export lift curves to GAP / MBAL / REVEAL or any third party software (Eclipse, VIP, etc). PROSPER Manual
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3.1.2.1 Statement Of The Problem A well is to be drilled to produce gas from a gas reservoir. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. It is required to: - Estimate the initial gas rate against a well head flowing pressure of 500 psig - Generate a well performance curve (Rate vs. well head flowing pressure) - Generate lift curves to be utilised by a simulator (Reveal, GAP, MBAL, Eclipse, VIP, and so on) 3.1.2.2 PVT Input Data Parameter Gas gravity: Separator pressure: Condensate to Gas Ratio: Condensate gravity: Water salinity: Impurities (CO2, N2, H2S):
Value 0.65 (Air =1) 250 psig 5 stb/MMscf 50 API 10000 ppm None
3.1.2.3 System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - deviation survey - surface equipment - down hole equipment - Geothermal gradient and - Average heat capacities 3.1.2.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB, mean sea level, seabed, and so on. The key thing is to describe all the equipment in the well in a manner that is consistent with respect to the origin selected. The well head depth does not have to be the origin of the deviation survey. Measured Depth in ft 0 5000
True Vertical Depth in ft 0 5000
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3.1.2.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.2.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, and so on. Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 4800 Casing 5000
Internal ft diameter inches N/A
Roughness in inches
2.441 6.1
in Rate multiplier
N/A
N/A
0.0018 0.0018
1 1
3.1.2.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth. It it is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft 0 5000
Static temperature in deg F 60 180
The overall heat transfer coefficient is 3 btu/h/ft2/F. Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. 3.1.2.3.5 Average Heat Capacities The default average heat capacities are to be used: Phase Oil: PROSPER Manual
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3.1.2.4 Reservoir Input Data PROSPER has around 20 different inflow models for gas wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Compaction Permeability Reduction model: Skin model: Permeability: Reservoir Thickness (True stratigraphic thickness): Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered: Mechanical skin:
Petroleum Experts 2500 psig 180 degF 0 stb/MMscf No Enter skin by hand 25 mD 80 ft 240 acres 31.6 0.354 ft 60 ft 0.1 days 0.2 0.2 Calculated Total permeability +5
Note: The Petroleum Experts' IPR method uses pseudo-pressure. It is transient and accounts for relative permeability effects. Please consult the online help for more details.
3.1.2.5 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - construct a PROSPER model for a producing dry gas well - use the PROSPER well model to estimate the flow rate against a WHFP of 500 psig - generate a well performance curve © 1990-2011 Petroleum Experts Limited
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- generate well VLP for a numerical simulator 3.1.2.5.1 System Options Here, one simply needs to launch PROSPER if not already done. Afterwards, simply selects | Options | Options and make the following choices Fluid: Dry and Wet Gas
Select | Done to complete this step. 3.1.2.5.2 PVT data Input In order to enter the PVT data, simply select | PVT | Input Data and populate the screen as shown below:
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Parameter Gas gravity: Separator pressure: Condensate to Gas Ratio: Condensate gravity: Water to Gas Ratio: Water salinity: Impurities (CO2, N2, H2S)
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Value 0.65 (Air =1) 250 psig 5 stb/MMscf 50 API 0 stb/MMscf 10000 ppm None
Select | Done to complete this step. 3.1.2.5.3 Saving the file
id data loss in case the computer crashes for instance. To save a file, simply select | File | Save as ... Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file.
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The rest is self-explanatory. 3.1.2.5.4 System Equipment Description In order to describe the system equipment (i.e the hardware in and around the well bore), simply select | System | Equipment (Tubing etc) | All
Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.2.5.4.1 Deviation Survey
Here are the data:
Measured Depth in ft 0 5000
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True Vertical Depth in ft 0 5000
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, the | Filter button located on the top right of this screen is used. In order to proceed with this example, select | Done and the next screen labelled Surface Equipment will follow.
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3.1.2.5.4.2 Surface Equipment
This model will not include any surface equipment. Therefore, one simply needs to select | Cancel to skip this step:
Selecting the "Cancel" button located on the top left corner of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.2.5.4.3 Down Hole Equipment
The down hole equipment includes the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 4800 PROSPER Manual
Internal ft diameter inches N/A 2.441
Roughness in inches
in Rate multiplier
N/A
N/A
0.0018
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5000
6.1
0.0018
698
1
The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This implies that the down hole equipment description stops at the top of the perforation. This is also true for a multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.2.5.4.4 Geothermal gradient
The data available are:
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Measured Depth in ft 0 5000
Static temperature in deg F 60 180
The overall heat transfer coefficient is 3 btu/h/ft2/F.
Select | Done to proceed to the average heat capacity screen. 3.1.2.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example.
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Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section can be accessed:
It will next be possible to visualise a sketch of the well bore with | Summary | Draw Down hole. 3.1.2.5.4.6 Equipment Summary
From the Equipment Data screen, select | Summary and the following table listing the various hardware components appear:
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If one then selects | Draw Down hole, this is the sketch of the well bore that would appear:
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Select | Main to exit the screen.
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3.1.2.5.4.7 Saving the PROSPER file
Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes for instance. To save a file, simply select | File | Save and then simply answer YES to the question "Do you want to overwrite this file?"
3.1.2.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follow: IPR model selection IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Compaction Permeability model: Skin model:
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To proceed, simply select the Input Data button (red if invalid) in the top right corner of the screen above: IPR data entry Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered:
25 mD 80 ft 240 acres 31.6 0.354 ft 60 ft 0.1 days 0.2 0.2 Calculated Total permeability
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Note: Because the Non-Darcy Flow Factor D has been set to "Calculated", PROSPER will automatically compute the Non-Darcy Flow Factor D. Otherwise, the User needs to enter it. From the screen above, select the tab "Mech/Geom Skin" at the bottom left corner of the screen in order to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
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IPR : Generating an IPR plot Once the IPR data input is completed, it is good practice to create an IPR plot to verify that everything make sense. For this, simply select | Calculate and the software will create and display the following plot:
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Please select | Main and then save the PROSPER file with | File | Save to secure all changes made so far. 3.1.2.5.6 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System (Ipr + Vlp) | 3 Variables as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline included in the model, the top node pressure is the well head flow pressure. The parameters water-gas-ratio (WGR) and condensate-gas-ratio (CGR) were entered earlier on the PVT screen and also on the IPR screen. However, during the life of a well either of these two parameters may change. Therefore, this screen allows one to sensitize on WGR and CGR. When sensitizing on the WGR and /or the CGR, PROSPER will use the new sensitivity values for the calculations. It will no longer use the WGR and CGR values entered on the IPR or the PVT screen. The same principle applies to any other sensitivity variables. Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. PROSPER Manual
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Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow Here select | Continue | Continue and | Calculate with the following results:
One can read a gas rate of 19.4 MMscf/d as solution rate in the right section of the screen under | Solution. The corresponding BHFP reads: 2093.9 psig. If one select | Plot | System Plot, the system plot (VLP + IPR plot) is displayed as follow:
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Note: The "E" on the VLP curves indicates that the erosional velocity limit is exceeded at the corresponding rates. Select | Main to get back to the main PROSPER screen and save the file to secure all changes made so far. 3.1.2.5.7 Well Performance Curve Generation A well performance is a plot of flow rate versus well head pressure at a given reservoir pressure. Therefore, generating a well performance is simply running sensitivities on the well head flowing pressure. In this example, we will vary the well head flowing pressure from a reasonably low well head pressure to the highest well head pressure to be expected: 50 psig to 2200 psig. For this, simply select | Calculation | System (IPR + VLP) | 3 Variables | Continue and here select the sensitivity variable "First Node Pressure":
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One can manually populate the cells with the desired values or generate them automatically with | Generate and here one need to enter the first value, the last value, the number of values and choose the values generation algorithm:
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To complete the process, simply select | Generate and then the input cells are populated accordingly:
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On can see that on this screen up to 3 variables can be sensitized on simultaneously. It is generally possible to sensitize on any number of parameters. With | Continue and then | Calculate, ten (10) set of VLP and IPR are computed. In order to see the performance curve for a well, select | Sensitivity. Now it is possible to select variables and plot any of the parameters listed versus the first node pressure (= well head flowing pressure).
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This is the plot of the Bottom Hole Flowing Pressure versus First Node pressure, the first node being the well head (read the label for the Y-axis). In order to plot the gas flow rate versus the first node pressure, select | Variables and then | Gas Rate for the Y axis variable:
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With | Done, the well performance curve appears as follow:
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This completes this section. Select | Main to return to the main screen of PROSPER. 3.1.2.5.8 Lift Curve generation for other applications
3.1.2.5.8.1 Introduction
Lift curves express the pressure drop across a tubing for a given set of variables. Different software providers use different formats and acronyms for lift curves. The most common acronyms are: - VLP for Vertical Lift Performance - TPD for Tubing Performance Data - TPC for Tubing Performance Curves - VFP for Vertical Flow Performance and so on. For naturally flowing gas wells, the variables involved in lift curve generation are: - Gas rate - Well Head flowing pressure (= first node pressure) - Water Gas Ratio (WGR) and - Condensate Gas Ratio (CGR). Even though four (4) variables are used, the lift curves for gas wells are conventionally referred to as 3-Variables VLP. The rate variable is taken for granted as one cannot calculate pressure drop without flow rate. The 3 variables for a naturally flowing gas well model are: WHFP, CGR & WGR.
Recommendation: In this example, we will demonstrate how to generate lift curves with PROSPER since lift curve generation is a key task that PROSPER is designed to perform. However, if a project involves the generation of lift curves for multiple wells, a more efficient approach would involve the use of GAP, the network modelling and optimisation tool developed by Petroleum Experts. Here are the reasons why: - GAP will instruct PROSPER to generate the lift curves using the very same PROSPER well model created by the user and linked to the well icon in GAP - GAP will use PROSPER to generate and save lift curves for any number of wells in batch-mode. This can be done overnight for instance to save time. - GAP will ask for the right VLP variables input depending upon the well type selected in GAP. The variable selection for lift curves can sometimes be delicate because different simulators use different names for the same quantity (example gas lift injection PROSPER Manual
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rate versus. GLR injected). 3.1.2.5.8.2 Steps
In order to generate the VLP, one first needs to work out the variables involved. Here these variables are gas rate, WHFP, CGR and WGR. The second step is to choose values for the variables in such a manner that the host application (GAP, MBAL, REVEAL, Eclipse, ..) can reasonably interpolate between them to find the solution needed. Extrapolation and very large variable spacing are to be avoided. In this example, the following values will be used: · Gas Rate: from 0.1 MMscf/d to 30 MMscf/d. The performance curve generated earlier shows that the well can produce maximum 20 MMscf/d. · WHFP: from 50 psig to 2200 psig; Those values will cover the entire response of the well as can be seen in the performance curve generated earlier. · WGR: from 0 to 300 stb/MMscf in this example. The right choice of the WGR values will require more knowledge about the drive mechanisms of the reservoir. For a waterdrive gas reservoir, high WGR will be expected. · CGR: for a dry and wet gas, the CGR is expected to remain constant by definition. NOTE: The user must consider using the retrograde condensate fluid model if the CGR is not expected to remain constant throughout. Beside the fully compositional approach, PROSPER also have a black oil model for retrograde condensate with fully retrograde behaviour. In order to enter the data for the lift curve generation, select | Calculation | VLP (Tubing Curves) | 3 Variables
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The next screen shot can be used to enter the range of rates to use:
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A few notes: On this screen, the values for top node pressure, water gas ratio and condensate gas ratio will be overwritten through the sensitivity variables. The user must ensure that the appropriate VLP correlation is selected. Here, the Petroleum Experts 2 correlation will be used. The "User Selected" rate type gives control to the user over the rates he /she think will best describe the response of the well. The user must also ensure that the first and last node are correctly selected.
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In order to proceed, select | Continue, select the relevant variables and populate the entries as per screen-shot below:
Now one shall select | Continue to proceed. The lift curve calculation is triggered with | Continue | Calculate.
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Be patient as this might take a while! At the end, a message will highlight that the calculation has completed.
It is always a good practice to plot and visualise the lift curve before exporting them. In this example, simply select | Plot and this is what would appear:
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Note: The "T" on the curve indicate that the rate are below the minimum Turner velocity criteria whereas the "E" indicates that the erosional velocity limit is exceeded. One can see that the lift curves have the right shape (J -curve) and look smooth. One can return to the previous screen with | Finish. In order to export the lift curve, select the button "Export Lift Curve"
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The following screen will appear where one has to select the format for the host application:
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The process is completed with | Continue | Save and the file is saved and edited automatically for viewing:
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Select | File | Exit | Main and this step completes this exercise.
3.1.3 Tutorial 02: Modelling a naturally flowing oil well File: ~/samples/PROSPER/T02_SimpleOilWell.OUT The main objectives of this example are to show: · How to set up a PROSPER model for a naturally flowing oil well · How to enter the PVT data · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP. · How to generate a well performance curve · How to generate and export lift curves to GAP/MBAL/REVEAL or any third party software (Eclipse, VIP and so on)
3.1.3.1 Statement Of The Problem A well is to be drilled to produce oil from an oil reservoir. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. © 1990-2011 Petroleum Experts Limited
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It is required to: - Estimate the initial flow rate against a well head flowing pressure of 250 psig - Generate a well performance curve (Rate vs. well head flowing pressure) - Generate lift curves to be utilised by a simulator (REVEAL, GAP, MBAL, Eclipse, VIP, and so on.) 3.1.3.2 PVT Input Data The basic available PVT data are: Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
3.1.3.3 System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment - Geothermal gradient and - Average heat capacities 3.1.3.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB an so on. The key thing is to describe all the equipment in the well in a manner consistent with respect to the origin selected. The well head depth does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 8000
True Vertical Depth in ft 0 8000
3.1.3.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.3.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ... PROSPER Manual
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Equipment type Xmas Tree (Well Head) Tubing Casing
Measured depth in ft (down to) 0
Internal diameter in inches N/A
7800 8000
3.992 8.3
728
Roughness in Rate multiplier inches N/A
N/A
0.0018 0.0018
1 1
3.1.3.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth. It is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft 0 8000
Static temperature in deg F 70 200
The overall heat transfer coefficient is 8 btu/h/ft2/F. Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. 3.1.3.3.5 Average Heat Capacities Here are the default average heat capacities to be used: Phase Oil: Gas: Water:
Heat Capacity in btu/lb/F 0.53 0.51 1
3.1.3.4 Reservoir Input Data PROSPER has more than 20 different inflow models for oil wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study. © 1990-2011 Petroleum Experts Limited
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IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Cut: Total GOR: Compaction Permeability Reduction model: Relative Permeability: Reservoir Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Mechanical skin:
Darcy / Enter Skin by hand 4000 psig 200 degF 0% 400 scf/stb No No 150 mD 100 ft 340 acres 31.6 0.354 ft +2
3.1.3.5 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Construct a PROSPER model for a producing an oil well - Use the PROSPER well model to estimate the flow rate against a WHFP of 250 psig - Generate a well performance curve - Generate well VLP for a numerical simulator 3.1.3.5.1 System Options Simply select | File | New if a PROSPER file is already open. Otherwise, select | Options | Options and make the following choices Fluid: Oil and Water
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Select | Done to complete this step. 3.1.3.5.2 PVT data Input In order to enter the PVT data, simply select |PVT|Input Data and populate the screen as shown below:
Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
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Select | Done to complete this step. 3.1.3.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes for instance. To save a file, simply select | File | Save as ... Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file.
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The rest is self-explanatory. 3.1.3.5.4 System Equipment Description In order to describe the hardware in / around the well bore (this is what the system equipment is), simply select | System | Equipment (Tubing etc) | All
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Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.3.5.4.1 Deviation Survey
Here are the data:
Measured Depth in ft 0 8000
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, the | Filter button located on the top right of this screen is to be used. Select | Done and the next screen labelled Surface Equipment will follow. 3.1.3.5.4.2 Surface Equipment
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Selecting the "Cancel" button located on the top left of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.3.5.4.3 Down Hole Equipment
The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, and so on.
Equipment type Xmas Tree (Well Head) Tubing Casing
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Internal diameter in inches N/A
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N/A
0.0018 0.0018
1 1
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The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This would mean that the down hole equipment description shall stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.3.5.4.4 Geothermal gradient
The data available are:
Measured Depth in ft 0 8000
Static temperature in deg F 70 200
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The overall heat transfer coefficient is 8 btu/h/ft2/F.
Select | Done to proceed to the average heat capacity screen. 3.1.3.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example.
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Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed:
It will be next possible to visualise a sketch of the well bore. 3.1.3.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary and this is what would appear:
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If one then selects | Draw Down hole this is the sketch of the well bore that would appear:
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Select | Main to exit the screen.
3.1.3.5.4.7 Saving the PROSPER file
Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes. To save a file, simply select | File | Save and then simply answer YES to overwriting the file.
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3.1.3.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follows: IPR model selection IPR model: Darcy Static Reservoir Pressure: 4000 psig Reservoir Temperature: 200 degF Water Cut: 0% Total GOR: 400 scf/stb Compaction Permeability ReductionNo model: Relative Permeability correction: No Skin model: Enter skin by hand
To proceed, select the Input Data button (red if invalid) in the top right corner of the screen above: IPR data entry PROSPER Manual
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Permeability: 150 mD Reservoir Thickness (True stratigraphic 100 ft thickness) : Drainage Area: 340 acres Dietz shape factor: 31.6 Well bore radius (Drill bit radius): 0.354 ft
From the screen above, select the the tab "Mech/Geom Skin" at the bottom left corner of the screen in order to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
+2
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IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything make sense. For this, select | Calculate and the software will create and display the following plot:
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Please select | Main and then save the PROSPER file with | File | Save to secure all changes made. 3.1.3.5.6 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System (Ipr + Vlp) | 3 Variables as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well any of these two parameters may change. Therefore, this screen allows to sensitize on both variables. When sensitizing on the water cut and / or the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified elsewhere. Surface Equipment Correlation: This applies to any pipeline in the model. Since this © 1990-2011 Petroleum Experts Limited
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model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
One can read an oil rate of 10 897.5 stb/d as solution rate. The corresponding BHFP reads: 2641.36 psig. If one selects | Plot | System Plot, the system plot (VLP + IPR plot) is displayed as follow:
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Select | Main to get back to the main PROSPER screen and save the file to secure all changes made. 3.1.3.5.7 Well Performance Curve Generation A well performance is a plot of flow rate versus well head pressure at a given reservoir pressure. Therefore, generating a well performance is simply running sensitivities on the well head flowing pressure, from a very low well head pressure to the highest possible well pressure that will shut-in the well. In this example, we will vary the well head flowing pressure from 50 psig to 1200 psig. For this, simply select | Calculation | System (IPR VLP) | 3 Variables | Continue and here select the sensitivity variable "First Node Pressure":
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One can manually populate the cells with the desired values or generate them automatically with | Generate and here one need to enter the first value, the last value, the number of values and the sequencing algorithm:
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To complete the process, simply select | Generate and then the input cells are populated accordingly: On can see that on this screen up to 3 variables can be sensitized on simultaneously. It is generally possibly to sensitize on any number of parameters. With | Continue | Calculate, ten (10) set of VLP and IPR are computed and can be plotted with | Plot | System Plot:
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well head flowing pressure. For this, select | Finish | Sensitivity and this is the plot that may appear:
This is the plot of the Bottom Hole Flowing Pressure versus First Node pressure, the first node being the well head. In order to plot the oil flow rate versus the first node pressure, one simply needs to select | Variables and then | Oil Rate for the Y axis variable:
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With | Done, the well performance curve appears as follow:
This is a well performance curve and completes this section. Select | Main to return to the main screen of PROSPER. © 1990-2011 Petroleum Experts Limited
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3.1.3.5.8 Lift Curve generation for other applications
3.1.3.5.8.1 Introduction
Lift curves express the pressure drop across a tubing for a given set of variables. Different software providers use different formats and acronyms for lift curves. The most common acronyms are: - VLP for Vertical Lift Performance - TPD for Tubing Performance Data - TPC for Tubing Performance Curves - VFP for Vertical Flow Performance and so on. For naturally flowing oil wells, the variables involved in lift curve generation are: - Liquid rate - Well Head flowing pressure (= first node pressure) - Water Cut and - GOR Even though in this case, four (4) variables will change, the lift curves are referred to as 3-Variables VLP. The rate variable is taken for granted because one cannot calculate pressure drop without flow rate. The VLP 3 variables for a naturally flowing oil well are: WHFP, GOR & Water Cut. Recommendation: In this example, we will demonstrate how to generate lift curves with PROSPER since lift curves generation is a key task that PROSPER is used to perform. However, if a project involves the generation of lift curves for multiple wells, a more efficient approach would involve the use of GAP, the network modelling and optimisation tool developed by Petroleum Experts. Here are the reasons why: - GAP will instruct PROSPER to generate the lift curves using the very same PROSPER well model created by the user and linked to the well icon in GAP - GAP will use PROSPER to generate and save lift curves for any number of wells in batch-mode. This can be done overnight for instance to save time. - GAP will ask for the right VLP variables input depending upon the well type defined by the user. The variable selection for VLP generation can sometime be delicate because different simulators use different names for the same quantity (example gas lift injection rate versus. GLR injected).
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3.1.3.5.8.2 Steps
In order to generate wells' VLP, one first needs to work out the variables involved. Here these variables are liquid rate, WHFP, GOR and Water Cut. The second step is to choose values for the variables in such a manner that the host application (GAP, MBAL, REVEAL, Eclipse, and so on) can reasonably interpolate between them to find the solution needed. Extrapolation and very large variable spacing are to be avoided. In this example, the following values will be used: · Liquid Rate: from 100 stb/d to 15 000 stb/d. The performance curve generated earlier shows that the well can produce a maximum of 12 000 stb/d without artificial lift. · WHFP: from 50 psig to 1500 psig; Those values will cover the following situations: from nearly fully open well to the full shut-in (see performance curve generated earlier). · Water cut: from 0 to 90%. · GOR: From 300 scf/stb to 15000 scf/stb. In order to enter the data for the lift curve generation , select | Calculation | VLP (Tubing Curves) | 3 Variables
The next screen shot can be used to enter the range of rates to use:
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A few notes: The values for top node pressure, water cut and GOR will be overwritten through the sensitivity variables. The user must ensure that the right VLP correlation is selected. Here, the Petroleum Experts 2 correlation will be used. The "User Selected" rate method give control to the user to enter the rates he /she think will best describe the expected operating ranges of the well. The user must ensure that the first and last node are correctly selected.
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In order to proceed, simply select | Continue, select the relevant variables and populate the entries as per screen-shot below:
Now one shall select | Continue to proceed. The lift curve calculation is triggered with | Continue | Calculate. Be patient as this might take a while! © 1990-2011 Petroleum Experts Limited
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At the end, a message will highlight that the calculation has completed.
It is always a good practice to plot and visualise the lift curve before exporting them. In this example, simply select | Plot and this is what would appear:
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One can see that the lift curves do all have the right shape (J -curve) and look smooth. One can return to the previous screen with | Finish. In order to export the lift curve, simply select the button "Export Lift Curve"
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The following screen will appear where one has to select the format for the host application (here Eclipse):
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The process is completed with | Continue | Save and the file is saved and edited automatically for viewing:
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Select | File | Exit | Main and this completes the exercise.
3.1.4 Tutorial 03: Modelling an oil well with black oil PVT matching File: ~/samples/PROSPER/T03_OilWellPVTMatching.OUT The main objectives of this example are to show: · How to set up a PROSPER model for an oil producing well · How to match calibrate the black oil correlations against actual PVT lab measurements · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP. · How to generate a well performance curve · How to generate and export lift curves to PGAP/MBAL/REVEAL or any third party software (Eclipse, VIP, etc)
3.1.4.1 Statement Of The Problem A well is to be drilled to produce oil from an oil reservoir. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. PROSPER Manual
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It is required to: - Build a PROSPER well model for an oil producing well - Calibrate the black oil correlations against lab data - Use the model to estimate the initial flow rate against a well head flowing pressure of 250 psig - Generate a well performance curve (Rate vs. well head flowing pressure) - Generate lift curves to be utilised by a simulator (PREVEAL, GAP, MBAL, Eclipse, VIP, etc) 3.1.4.2 PVT Input Data The basic available PVT data are: Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S): Bubble point pressure:
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None 2500 psig at 200 degF
Further PVT data are given in tabular form below at 200 degF: Pressure in psig Gas Oil Ratio in scf/ Oil FVF in rb/stb stb 1500 237 1.138 2000 324 1.178 2500 400 1.214 3000 400 1.207 4000 400 1.198
Oil Viscosity in centipoises 1.34 1.15 1.01 1.05 1.11
3.1.4.3 System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment - Geothermal gradient and - Average heat capacities 3.1.4.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB etc. The key thing is to describe all the equipment in the well in a manner consistent with the origin selected. © 1990-2011 Petroleum Experts Limited
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The well head depth does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 8000
True Vertical Depth in ft 0 8000
3.1.4.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.4.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves and so on. Equipment type Xmas Tree (Well Head) Tubing Casing
Measured depth in ft (down to) 0
Internal diameter in inches N/A
7800 8000
3.992 8.3
Roughness in Rate multiplier inches N/A
N/A
0.0018 0.0018
1 1
3.1.4.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth. It is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft 0 8000
Static temperature in deg F 70 200
The overall heat transfer coefficient is 8 btu/h/ft2/F. Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. PROSPER Manual
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3.1.4.3.5 Average Heat Capacities Here are the default average heat capacities that will be used: Phase Oil: Gas: Water:
Heat Capacity in btu/lb/F 0.53 0.51 1
3.1.4.4 Reservoir Input Data PROSPER has more than 20 different inflow models for oil wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
IPR model: Darcy / Enter Skin by hand Static Reservoir Pressure: 4000 psig Reservoir Temperature: 200 degF Water Cut: 0% Total GOR: 400 scf/stb Compaction Permeability Reduction No model: Relative Permeability: No Reservoir Permeability: 150 mD Reservoir Thickness (True stratigraphic 100 ft thickness) : Drainage Area: 340 acres Dietz shape factor: 31.6 Well bore radius (Drill bit radius): 0.354 ft Mechanical skin: +2
3.1.4.5 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Build a PROSPER well model for an oil producing well - Calibrate the black oil correlations against lab data - Use the model to estimate the initial flow rate against a well head flowing pressure of 250 psig - Generate a well performance curve (Rate vs. well head flowing pressure) - Generate lift curves to be utilised by a simulator (REVEAL, GAP, MBAL, Eclipse, VIP, © 1990-2011 Petroleum Experts Limited
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etc) 3.1.4.5.1 System Options Simply select | File | New if a PROSPER file is already open. Otherwise, select | Options | Options and make the following choices: Fluid: Oil and Water. All other settings can be left to their defaults options.
Select | Done to complete this step. 3.1.4.5.2 PVT data Input In order to enter the PVT data, simply select | PVT | Input Data and populate the screen as shown below:
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Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
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Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
In order to enter the lab measurements at different pressures, select the | Match Data button and populate the table as follow:
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Select | Done to get back to the PVT input screen PVT regression Now select |Regression | Match All to kick the non-linear regression algorithm. The following screen will confirm when the regression is completed.
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In order to quality-check the regression, select | OK | Parameters and this is what can be seen:
Please consult the online help to get the details about the regression algorithm. Ideally, Parameter 1, which is a multiplier, should be close to unity whereas the shift (Parameter 2) is expected to be around nil. On the basis of the results obtained here, we will proceed with the combination Glaso / Petrosky. For this, select | Done | Done and choose the appropriate black oil correlations as per screen-shot below:
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Select | Done and this complete this step. 3.1.4.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes. To save a file, simply select | File | Save as. Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file.
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The rest is self-explanatory. 3.1.4.5.4 System Equipment Description In order to describe the system equipment (i.e the hardware in and around the well bore), simply select | System | Equipment (Tubing etc) | All
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Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.4.5.4.1 Deviation Survey
Here are the data:
Measured Depth in ft 0 8000
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True Vertical Depth in ft 0 8000
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, the | Filter button located on the top right of this screen is to be used. Select | Done and the screen labelled Surface Equipment will follow. 3.1.4.5.4.2 Surface Equipment
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Selecting the "Cancel" button located on the top left of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.4.5.4.3 Down Hole Equipment
The down hole equipment includes the tubings, casings, nipples, Sub-surface Safety valves and so on.
Equipment type Xmas Tree (Well Head) Tubing Casing
PROSPER Manual
Measured depth in ft (down to) 0
Internal diameter in inches N/A
7800 8000
3.992 8.3
Roughness in Rate multiplier inches N/A
N/A
0.0018 0.0018
1 1
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The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This implies that the down hole equipment description must stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.4.5.4.4 Geothermal gradient
The data available are:
Measured Depth in ft 0 8000
Static temperature in deg F 70 200 © 1990-2011 Petroleum Experts Limited
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The overall heat transfer coefficient is 8 btu/h/ft2/F.
Select | Done to proceed to the average heat capacity screen. 3.1.4.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example.
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Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed:
3.1.4.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary and this is what would appear:
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If one then selects | Draw Down hole this is the sketch of the well bore that appears:
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Select | Main to exit the screen.
3.1.4.5.4.7 Saving the PROSPER file
It is recommended to save / overwrite the file at this stage. To save the file, simply select | File | Save and then simply answer YES to overwriting the file. 3.1.4.5.5 Inflow Performance Relation (IPR) To select the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follows: IPR model selection IPR model: Darcy Static Reservoir Pressure: 4000 psig Reservoir Temperature: 200 degF Water Cut: 0% Total GOR: 400 scf/stb Compaction Permeability ReductionNo model: Relative Permeability correction: No © 1990-2011 Petroleum Experts Limited
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Skin model:
Enter skin by hand
To proceed, simply select the Input Data button (red if invalid) in the top right corner of the screen above: IPR data entry Reservoir Permeability: 150 mD Reservoir Thickness (True stratigraphic 100 ft thickness) : Drainage Area: 340 acres Dietz shape factor: 31.6 Well bore radius (Drill bit radius): 0.354 ft
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From the screen above, select the the tab "Mech/Geom Skin" at the bottom left corner of the screen to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
+2
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IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything makes sense. For this, simply select | Calculate and the software will create and display the following plot:
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Please select | Main and then save the PROSPER file with | File | Save to secure all changes made so far. 3.1.4.5.6 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System | 3 Variables as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well either parameter may change. Therefore, this screen allow the user to sensitize both. When sensitizing on the water cut and / or the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified elsewhere. Surface Equipment Correlation: This applies to any pipeline in the model. Since this © 1990-2011 Petroleum Experts Limited
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model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
One can read an oil rate of 10 500 stb/d as solution rate. The corresponding BHFP reads: 2584 psig. If one selects | Plot | System Plot, the system plot (VLP + IPR plot) is displayed as follow:
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Select | Main to get back to the main PROSPER screen and save the file to secure all changes made so far. 3.1.4.5.7 Well Performance Curve Generation A well performance is a plot of flow rate versus well head pressure at a given reservoir pressure. Therefore, generating a well performance simply means running sensitivities on the well head flowing pressure, from a very low well head pressure to the highest possible well pressure that will shut-in the well. In this example, we will vary the well head flowing pressure from 50 psig to 1200 psig. For this, simply select | Calculation | System (IPR VLP) | 3 Variables | Continue and here select the sensitivity variable "First Node Pressure":
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One can manually populate the cells with the desired values or generate them automatically with | Generate. Afterwards, one needs to enter the first value, the last value, the number of values and the sequencing algorithm:
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To complete the process, simply select | Generate and then the input cells are populated accordingly: One can see that on this screen up to 3 variables can be sensitized on simultaneously. It is generally possibly to sensitize on any number of parameters. With | Continue | Calculate, ten (10) sets of VLP and IPR are computed. To visualise a plot of the solution rate versus first node pressure, select | Sensitivity.
This is the plot of the Bottom Hole Flowing Pressure versus First Node pressure, the first node being the well head. © 1990-2011 Petroleum Experts Limited
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In order to plot the oil flow rate versus the first node pressure, one simply needs to select | Variables and then | Gas Rate for the Y axis variable:
With | Done, the well performance curve appears as follow:
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This completes this section. Select | Main to return to the main screen of PROSPER. 3.1.4.5.8 Lift Curve generation for other applications
3.1.4.5.8.1 Introduction
Lift curves express the pressure drop across a tubing for a given set of variables. Different software providers use different formats and acronyms for lift curves. The most common acronyms are: - VLP for Vertical Lift Performance - TPD for Tubing Performance Data - TPC for Tubing Performance Curves - VFP for Vertical Flow Performance and so on. For naturally flowing oil wells, the variables involved in lift curve generation are: - liquid rate - Well Head flowing pressure (= first node pressure) - Water Cut and © 1990-2011 Petroleum Experts Limited
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- GOR Even though in this case, four (4) variables will change, the lift curves are referred to as 3-Variables VLP. The rate variable is taken for granted as one cannot calculate pressure drop without flow rate. The 3 VLP variables for a naturally flowing oil well are: WHFP, GOR & Water Cut. Recommendation: In this example, we will demonstrate how to generate lift curves with PROSPER since lift curve generation is a key task that PROSPER is used to perform. However, if a project involves the generation of lift curves for multiple wells, a more efficient approach would involve the use of GAP, the network modelling and optimisation tool developed by Petroleum Experts. Here are the reasons why: - GAP will instruct PROSPER to generate the lift curves using the very same PROSPER well model created by the user and linked to the well icon in GAP - GAP uses PROSPER to generate and save lift curve for any number of wells in batchmode. This can be done overnight for instance to save time. - GAP will ask for the right VLP variables input depending upon the well type. The variable selection for lift curves can sometimes be delicate because different simulators use different names for the same quantity (example gas lift injection rate versus. GLR injected). 3.1.4.5.8.2 Steps
In order to generate wells' VLP, one first needs to work out the variables involved. Here these variables are liquid rate, WHFP, GOR and Water Cut. The second step is to choose values for the variables in such a manner that the host application (GAP, MBAL, REVEAL, Eclipse, etc) can reasonably interpolate between them to find the solution needed. Extrapolation and very large variable spacing are to be avoided. In this example, the following values will be used: · Liquid Rate: from 100 stb/d to 15 000 stb/d. The performance curve generated earlier shows that the well can produce a maximum of 12 000 stb/d without artificial lift. · WHFP: from 50 psig to 1500 psig; Those values will cover the following situations: from nearly fully open well to the full shut-in (see performance curve generated earlier). · Water cut: from 0 to 100%. · GOR: From 300 scf/stb to 15000 scf/stb. In order to enter the data for the lift curve generation , select | Calculation | VLP (Tubing Curves) | 3 Variables
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The next screen shot can be used to enter the range of rates to use:
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A few notes: The values for top node pressure, water cut and GOR will be overwritten through the sensitivity variables. One should make sure that the right VLP correlation is selected. Here, the Petroleum Experts 2 correlation will be used. The "User Selected" rate method gives control to the user to enter the rates he /she think will best describe the expected operating ranges of the well. One should also ensure that the first and last node are correctly selected.
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In order to proceed, simply select | Continue, select the relevant variables and populate the entries as per screen-shot below:
Now simply select | Continue to proceed. The lift curve calculation is triggered with | Calculate.
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Be patient as this might take a while! At the end, a message will confirm that the calculation has completed.
It is always a good practice to plot and visualise the lift curves before exporting them. In this example, simply select | Plot and this is what appears:
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One can see that the lift curves do all have the right shape (J -curve) and look smooth. One can return to the previous screen with | Finish. In order to export the lift curve, simply select the button "Export Lift Curve".
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The following screen will appear where one has to select the format for the host application (here Eclipse):
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The process is completed with | Continue | Save and the file is saved and edited automatically for viewing: Select | File | Exit | Main and this completes the exercise.
3.1.5 Tutorial 04: Modelling an horizontal oil well File: ~/samples/PROSPER/T04_HorizontalOilWell.out The main objectives of this example are to show: · How to set up a PROSPER model for a horizontal oil well · How to enter basic black oil PVT data · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP of 250 psig. © 1990-2011 Petroleum Experts Limited
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· How to generate a well performance curve · How to generate and export lift curves to GAP/MBAL/REVEAL or any third party software (Eclipse, VIP, an so on)
3.1.5.1 Statement Of The Problem A horizontal well is to be drilled to produce oil. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. It is required to: - Estimate the initial oil rate against a well head flowing pressure of 250 psig - Perform sensitivity runs on the horizontal well length for 500 ft, 1000 ft, 1500 ft, 2000 ft, 2500 ft and 3000 ft. - Sensitize simultaneously on water cut of 0 %. 10%, 20%, 30%, 40% and 50%. 3.1.5.2 PVT Input Data The basic available PVT data are: Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
Bubble point pressure:
2500 psig at 200 degF
Further PVT data are given in tabular form below at 200 degF: Pressure in psig 1500 2000 2500 3000 4000
Gas Oil Ratio in scf/ Oil FVF in rb/stb stb 237 1.138 324 1.178 400 1.214 400 1.207 400 1.198
Oil Viscosity centipoises 1.34 1.15 1.01 1.05 1.11
in
3.1.5.3 System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment PROSPER Manual
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- Geothermal gradient and - Average heat capacities 3.1.5.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB and so on. The key thing is to describe all the equipment in the well in a manner consistent with the origin selected. The well head depth does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 8050 10050
True Vertical Depth in ft 0 8050 8050
3.1.5.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.5.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, and so on.
Equipment type Xmas Tree (Well Head) Tubing Casing
Measured depth in ft (down to) 0
Internal diameter in inches N/A
7800 8050
3.992 8.3
Roughness in Rate multiplier inches N/A
N/A
0.0018 0.0018
1 1
3.1.5.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth. It is the temperature gradient based upon the true vertical depth that is used during the calculation.
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Measured Depth in ft 0 8050 10050
Static temperature in deg F 70 200 200
The overall heat transfer coefficient is 8 btu/h/ft2/F. The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. Note:
3.1.5.3.5 Average Heat Capacities Here are the default average heat capacities that will be used: Phase Oil: Gas: Water:
Heat Capacity in btu/lb/F 0.53 0.51 1
3.1.5.4 Reservoir Input Data Here are the data describing the inflow performance relationship for the well: IPR model: Horizontal Well - No Flow Boundary Static Reservoir Pressure: 4000 psig Reservoir Temperature: 200 degF Water Cut: 0% Total GOR: 400 scf/stb Compaction Permeability Reduction model: No Skin model: Enter skin by hand Relative Permeability correction: No Permeability: 150 mD Reservoir Thickness (True stratigraphic thickness) 100 ft : Well bore radius: 0.354 ft Horizontal Anisotropy: 1 (fraction) Vertical anisotropy: 0.1 (fraction) Producing length: 2000 ft Reservoir Length: 5000 ft Reservoir width:
5000 ft
Distance along length edge to centre of well:
2500 ft
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Distance along length edge to centre of well: Distance from bottom to centre of well: Mechanical skin:
802
2500 ft 50 ft +5
3.1.5.5 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Construct a PROSPER model for a horizontal oil well - Use the PROSPER well model to estimate the flow rate against a WHFP of 250 psig - Perform sensitivity on well producing length and water cut 3.1.5.5.1 System Options Here, one simply select | File | New if a PROSPER file is already open. Afterwards, select | Options | Options and make the following choices Fluid: Oil and Water. All other settings can be left to their defaults values.
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Select | Done to complete this step. 3.1.5.5.2 PVT data Input In order to enter the PVT data, simply select | PVT | Input Data and populate the screen as shown below:
Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S): Bubble point pressure:
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Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None 2500 psig at 200 degF
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Now select | Match Data to enter the lab data given in the table below: Reference temperature: 200 degF
Pressure in psig 1500 2000 2500 3000 4000
Gas Oil Ratio in scf/ Oil FVF in rb/stb stb 237 1.138 324 1.178 400 1.214 400 1.207 400 1.198
Oil Viscosity centipoises 1.34 1.15 1.01 1.05 1.11
in
In order to enter the PVT lab data, select | Match Data and populate the screen as follow:
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PVT regression Afterwards, select | Done and then | Regression | Match All. This will start the non-linear regression algorithm. The following screen will confirm when the regression is completed.
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In order to quality-check the regression, select | OK | Parameters and this is what can be seen:
In essence the regression algorithm uses a multiplier (Parameter 1) and a shift (Parameter 2). Ideally, Parameter 1 should be close to unity whereas the shift (Parameter 2) is expected to be around nil. On the basis of the results obtained here, we will proceed with the combination Glaso / Petrosky. For this, select | Done | Done and choose the appropriate black oil correlations as per screen-shot below:
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Select | Done and this completes this step. 3.1.5.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes. To save a file, simply select | File | Save as. Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file. 3.1.5.5.4 System Equipment Description In order to describe the system equipment (i.e the hardware in and around the well bore), simply select | System | Equipment (Tubing etc) | All
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Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.5.5.4.1 Deviation Survey
Here are the data:
Measured Depth in ft 0 8050 10050
True Vertical Depth in ft 0 8050 8050
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, use the | Filter button located on the top right of this screen. Select | Done and the screen labelled Surface Equipment will follow. 3.1.5.5.4.2 Surface Equipment
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Make sure that the Choke Method is set to ELF (see bottom left corner of screen). The selected choke model is used to compute pressure across surface chokes and eventual down hole restrictions. For validation purposes only, one should enter a temperature of surroundings of 70 degF and an overall heat transfer coefficient of 8 Btu/h/ft2/F. Note that in this example, the temperature of surroundings and the overall heat transfer coefficient entered will not affect the results because there is no pipeline in the model. Selecting the "Cancel" button located on the top left of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.5.5.4.3 Down Hole Equipment
The down hole equipment includes the tubings, casings, nipples, Sub-surface Safety valves and so on.
Equipment type Xmas Tree (Well
Measured depth in ft (down to) 0
Internal diameter in inches N/A
Roughness in Rate multiplier inches N/A
N/A
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Head) Tubing Casing
7800 8050
3.992 8.3
0.0018 0.0018
1 1
The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This implies that the down hole equipment description will stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.5.5.4.4 Geothermal gradient
The data available are:
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Measured Depth in ft 0 8050
812
Static temperature in deg F 70 200
The overall heat transfer coefficient is 8 btu/h/ft2/F.
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Select | Done to proceed to the average heat capacity screen. 3.1.5.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example
Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed:
3.1.5.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary and this is what would appear:
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If one then selects | Draw Down hole this is the sketch of the well bore that appears:
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Select | Main to exit the screen.
3.1.5.5.4.7 Saving the PROSPER file
It is recommended to save / overwrite the file at this stage. To save the file, simply select | File | Save and then simply answer YES to overwriting the file. 3.1.5.5.5 Inflow Performance Relation (IPR) To select the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follows: IPR model selection IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Cut: Total GOR: Compaction Permeability model: PROSPER Manual
Horizontal Well - No Flow Boundary 4000 psig 200 degF 0% 400 scf/stb ReductionNo
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816
No Enter skin by hand
To proceed, simply select the Input Data button in the top right corner of the screen above: IPR data entry
Permeability: 150 mD Reservoir Thickness (True stratigraphic thickness) 100 ft : Well bore radius: 0.354 ft Horizontal Anisotropy: 1 (fraction) Vertical anisotropy: 0.1 (fraction) Producing length: 2000 ft Reservoir Length: 5000 ft Reservoir width:
5000 ft
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Distance along length edge to centre of well: Distance along length edge to centre of well: Distance from bottom to centre of well:
2500 ft 2500 ft 50 ft
From the screen above, select the the tab "Mech/Geom Skin" at the bottom left corner of the screen to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
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IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything makes sense. For this, simply select | Calculate and the software will create and display the following plot:
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Please select | Main and then save the PROSPER file with | File | Save to secure all changes made. 3.1.5.5.6 Sensitivity on well length and water cut The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System (Ipr + Vlp) | 3 Variables as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well any of these either parameter may change. Therefore, this screen allow the user to sensitize with the GOR and water cut. When sensitizing on the water cut and / or the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified elsewhere.
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Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue and then select the sensitivity variables well length and water cut as follow:
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After entering the values for well length and water cut, select | Continue | Calculate and | Plot | System Plot to visualise the IPR + VLP plots:
Select | Main to get back to the main PROSPER screen . This completes this exercise.
3.1.6 Tutorial 05: Modelling a multilateral Dry Gas Producer File: ~/samples/PROSPER/T05_MultilateralGasWell.Out A multilateral well is a well that has more than one lateral going out of the bore hole and connecting the well with the one or multiple reservoirs. Objectives of multilaterals are either to produce a larger drainage area than a single mono-bore or to access multiple reservoirs from a single mother bore. The main objectives of this example are to show: · How to set-up a multilateral well model in PROSPER · How to use the model to predict the gas production rate from the well against a well head pressure of 200 psig. · Determine the contribution of each lateral. · Determine the pressure drop in each lateral. PROSPER Manual
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3.1.6.1 Statement Of The Problem It is intended to drill a multilateral gas well with 2 laterals draining the same gas reservoir as shown in the screen shot below:
It is intended to build a PROSPER well model for the well. Once the well model is constructed, it will be used to predict the flow rate when the well head pressure is 200 psig. Note that PROSPER can also model a configuration where each lateral penetrates different multiple reservoirs. 3.1.6.2 PVT Input Data The information in the next table describes the PVT properties of the fluid. Reservoir Fluid : Dry and Wet Gas Gas Gravity : 0.63 Separator Pressure : 500 Condensate To Gas Ratio 0 : Condensate Gravity : 50 Water To Gas Ratio : 2 Water Salinity : 100000 Mole Percent H2S : 0
(sp. gravity) (psig) (STB/MMscf) (API) (STB/MMscf) (ppm) (percent)
Mole Percent C02 :
0.15
(percent)
Mole Percent N2 :
3.6
(percent)
Gas Viscosity CorrelationLee et al :
The following lab measurements are also available:
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PVT lab data at a reference temperature of 65 degF: Pressure [psig]
Z Factor -
Gas viscosity [cP]
Gas FVF [ft3/scf]
100 225 350 475 600
0.9815 0.9613 0.9412 0.9213 0.9017
0.0109 0.01109 0.01127 0.01147 0.01171
0.1271 0.0595 0.0383 0.0279 0.0218
3.1.6.3 System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment - Geothermal gradient and - Average heat capacities 3.1.6.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, mean sea level, RKB and so on. The key thing is to describe all the equipment in the well in a manner consistent with the origin selected. The well head depth does not have to coincide with the origin of the deviation survey.
Measured Depth (feet) 0 900 1068 1188 1285 1360 1516 1578
True Vertical Depth (feet) 0 900 1062.3 1164.1 1237.7 1288.8 1374.1 1398.4
The deviation survey here must stops at the tie-point: the node that links the tubing to the down hole network of the laterals. This deviation will affect the pressure drop of the commingled flow that arrives at surface. The contribution of each lateral and its impact of pressure drop down hole will be accounted by the multilateral IPR model.
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3.1.6.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.6.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, and so on. Consistent with the deviation survey, this section will describe all equipment between the well head and the tie-point.
Equipment Type Xmas Tree Tubing SSSV Tubing
Measured Depth in ft 0 260 N/A 1577
Tubing Internal Diameter in inches N/A 6 4.5 6
3.1.6.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth and it is the temperature gradient based upon the true vertical depth that is used during the calculation.
Formation measured Depth in ft 0 1578
Formation Temperature in degF 40 62
The overall heat transfer coefficient is 3 btu/h/ft2/F. Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. 3.1.6.3.5 Average Heat Capacities Here the default average heat capacities will be used: Phase Oil:
Heat Capacity in btu/lb/F 0.53 © 1990-2011 Petroleum Experts Limited
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Gas: Water:
0.51 1
3.1.6.4 Multilateral IPR Data Available data from the Tie point to the reservoir: Tie point data Measured Depth True Vertical Depth
1577 1398.4
(feet) (feet)
For the equipment T1, i.e. the pipe between Tie Point Data to Joint 1: Deviation survey: Measured Depth in ft 1577 1650
True Vertical Depth in ft 1398.4 1424.3
Azimuth in degrees 0 230.6
Equipment data: Equipment Type Tubing
Measured Depth Inside Diameter (feet) (inches) 1650 7
Inside Roughness (inches) 0.0006
Joint data Measured Depth: True Vertical Depth:
1650 1424.3
(feet) (feet)
Lateral 1 data Well bore radius: 0.354 ft Dietz shape factor: 31.6 Lateral 1 deviation survey: Measured Depth in ft 1650 1701 1840 PROSPER Manual
True Vertical Depth in ft 1424.3 1437 1449.3
Azimuth in degrees 230.6 243 264.9 May, 2011
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Lateral 1 equipment data: Equipment Measured Depth in ft Type Tubing 1900
Tubing ID in inches 3.5
Tubing Roughness in inches 0.0006
Lateral 1 perforation data: Perforation Perforation Perforati Perforati Interval (MD) Interval (MD) on on Start in ft End in ft Interval Interval (TVD) (TVD) Start in ft End in ft 1650 1900 1424.3 1450.3
Local (Mechanical) Skin Value
Non-Darcy Flow Factor
0
2.80E-10
Lateral 2 data Well bore radius: 0.354 ft Dietz shape factor: 31.6 Lateral 2 deviation survey: Measured Depth in ft 1650 1710 1784 1908 2024 2155 2290 2395 2436 2483
True Vertical Azimuth in Depth in ft degrees 1424.3 230.6 1430.1 231.3 1432.7 239.2 1432.2 257.6 1438.5 267.1 1447.9 256.6 1445.8 248.1 1449.8 238.8 1449.9 235 1449.8 231
Lateral 2 equipment data:
Equipment Type
Measured Depth (feet)
Tubing Inside Diameter (inches)
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Tubing
2483
4
0.0006
Lateral 2 perforation data:
Perforation Interval (MD) Start in ft
1670
Perforation Local Non-Darcy Interval (MD) Perforation Perforation (Mechanic Flow Factor) Interval Interval End in ft al) Skin (TVD) Start (TVD) End Value in ft in ft 2483 1426.23 1449.8 0 2.80E-10
Reservoir data Reservoir model: Petroleum Experts PVT data: Reservoir Pressure Reservoir Temperature Condensate Gravity Reservoir Gas Gravity Reservoir Water Salinity Water Gas Ratio Condensate Gas Ratio
557 65 45 0.63 10000 2 0
(psig) (deg F) (API) (sp. gravity) (ppm) (STB/MMscf) (STB/MMscf)
Petrophysical parameters: Reservoir Permeability 244 Reservoir Thickness 50 Drainage Area 500 Reservoir Top Depth (TVD) 1400 Reservoir Vertical25 Permeability Reservoir Porosity 0.28 Connate Water Saturation 0.25
(md) (feet) (acres) (feet) (md) (fraction) (fraction)
3.1.6.5 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem:
· Set-up a multilateral well model for a dry gas producer in PROSPER · Use the model to predict the gas production rate from the well against a well head pressure of 200 psig. · Determine the contribution of each lateral. PROSPER Manual
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· Determine the pressure drop in each lateral. 3.1.6.5.1 System Options Here, one simply select | File | New if a PROSPER file is already open. Select | Options | Options and make the following choices Fluid: Dry and Wet Gas Inflow Type: Multilateral Well
Select | Done to complete this step.
3.1.6.5.2 PVT data Input The information in the next table describes the PVT properties of the fluid. © 1990-2011 Petroleum Experts Limited
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Reservoir Fluid : Gas Gravity (air=1) : Separator Pressure in psig: Condensate To Gas Ratio in stb/MMscf: Condensate Gravity in API: Water To Gas Ratio in stb/MMscf: Water Salinity in ppm: Mole Percent H2S in mole percent:
Dry and Wet Gas 0.63 200 0 50 2 100000 0
Mole Percent C02 in mole percent:
0.15
Mole Percent N2 in mole percent:
3.6
Gas Viscosity Correlation :
Lee et al
The following lab measurements are also available for PVT calibration at a reference temperature of 65 degF:
Pressure [psig] 100 225 350 475 600
Z Factor 0.9815 0.9613 0.9412 0.9213 0.9017
Gas viscosity [cP] 0.0109 0.01109 0.01127 0.01147 0.01171
Gas FVF [ft3/scf] 0.1271 0.0595 0.0383 0.0279 0.0218
Select | Input Data and then enter the fluid parameters at stock tank conditions:
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In order to enter the lab data, select | Match Data and populate the table with the data provided:
Here select | Done and then | Regression | Match all and the | Parameters to see the dialog below: .
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For all PVT data, the parameter 1 is close to unity and the parameter 2 practically zero. This indicates that the PVT data are of good quality and will be used for for this model. The Lee et al Viscosity model requires the least correction and will therefore be selected. Note that a green message is being flashed to remind the use that the PVT data has been matched. Select | Done | Main to complete this. 3.1.6.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss if for example the computer crashes. To save a file, simply select | File | Save as. Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file.
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The rest is self-explanatory. 3.1.6.5.4 System Equipment Description In order to describe system equipment (ie. the the hardware in and around the well bore), simply select | System | Equipment (Tubing etc) | All
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Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.6.5.4.1 Deviation Survey
Here are the data:
Measured Depth (feet) 0 900 1068 1188 1285 1360 1516 1578
True Vertical Depth (feet) 0 900 1062.3 1164.1 1237.7 1288.8 1374.1 1398.4
With | Edit, one shall populate the deviation survey screen as follow:
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Note: It is possible to input or import a large deviation survey table into PROSPER. A © 1990-2011 Petroleum Experts Limited
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filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, use the | Filter button located on the top right of this screen. Select | Done and the next screen labelled Surface Equipment will follow. 3.1.6.5.4.2 Surface Equipment
This model will not include any surface equipment. Selecting the "Cancel" button located on the top left corner of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.6.5.4.3 Down Hole Equipment
The down hole equipment includes the tubings, casings, nipples, Sub-surface Safety valves, and so on. Equipment type
Measured Depth in ft
Tubing Inside Diameter in inches
Xmas Tree Tubing SSSV Tubing
0 260 N/A 1577
6 4.5 6
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Select | Done to proceed to the next screen: the geothermal gradient. 3.1.6.5.4.4 Geothermal gradient
The data available are: Formation Measured Depth in ft Formation in degF 0 1578
40 62
The overall heat transfer coefficient is 3 btu/h/ft2/F.
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Select | Done to proceed to the average heat capacity screen. 3.1.6.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed. 3.1.6.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary | Draw Down Hole and this is the sketch of the well bore that would appear:
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Select | Main to exit the screen.
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3.1.6.5.4.7 Saving the PROSPER file
Like working with any other computer program, it is good practice to save the file frequently in order to avoid possible data loss. To save a file, simply select | File | Save and then simply answer YES to the question "Do you want to overwrite this file?" 3.1.6.5.5 Multilateral IPR Input section Drawing the model To access the interface where to describe the multilateral IPR, select | System I Inflow Performance. The IPR interface consist in a Network section where we can draw the situation of the example using the short cut icons.
From left to right, the icons represent: - Tie-Point: this is the depth at which the combined IPR is computed. - Junction: this is a node from where a lateral can branch out. - Completion: this describes the details of the perforation and - Reservoir: contains the pertinent reservoir data like pressure, permeability, Dietzshape factor and so on. Select the first short cut icon starting from left, or click on the drop down menu and select "Add Tie-point" as shown in the next screen shot.
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Click anywhere in the blank screen to add a Tie point and give it the label "Tie point".
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the icon. The next short cut icon (Going from left to right) is the Add Junction. Select Add Junction and click somewhere else in the screen to add the junction, label it "Joint". Then select the Add Completion next to the "Add Junction" and click in the screen to add a completion, label it "Lateral 1". Click somewhere else in the screen to add a second completion, named it "Lateral 2". Then select Add Reservoir from the drop down menu and click on the screen to add a Reservoir icon.Label it "Reservoir" One should have a schematic similar to the next screen shot.
From the drop down menu, the user may select the command "Move" and then select any object to move it around. The next step is to connect the different objects together, so we can select the command "Add Link" from the drop down menu. Then click on the Tie point and drag it to the Joint, this will create a connection between them.
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Repeat the process of linking the following items: · · · ·
Joint to Lateral 1 Lateral 1 to Reservoir Joint to Lateral 2 Lateral 2 to Reservoir
Entering the data Tie point: Measured Depth = 1577 ft and True vertical Depth = 1398.4 ft At this stage we need to start entering the data for the different sections. Double click on the Tie point added icon to access the input panel. Enter the depths of the Tie point as shown in the next snap shot.
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Click Done to exit this section and keep the changes. Casing from Tie point to Joint Double click on the next element called "T1" which is a piece of casing going from the Tie point to the joint where the laterals are separated.
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Select the Input Data tab to access the deviation survey input screen and the equipment tabs: Deviation survey tab:
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Equipment Tab:
Once the two tabs are completed click on Done. Joint Double click on the Joint icon. In this section the data has been transferred automatically from the deepest point of the previous element. On the right hand side we can see a that the elements that need to be completed are marked with a red x.
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Click Done. Lateral 1 Double click on lateral 1 to access the input panel of the completion element. Enter the well-bore radius and Dietz shape factor as shown below. Click Input Data.
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Select the Input Data tab at the top right corner of the screen to proceed. In the Input data section there are 3 tabs to complete (Deviation, Equipment, Perforation Details). The 3 sections are shown below in the following screen shots: Deviation:
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Equipment:
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Perforation Details:
Click Done to exit and save the changes in this section. Lateral 2: Double click on the lateral 2 to start entering the information for this icon. Enter the well-bore radius and Dietz shape factor, then click Input data to move to the next section.
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In the Input Data section there are 3 tabs to enter the data: Lateral 2 Deviation:
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Lateral 2 Equipment:
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Lateral 2 Perforations:
Click Done to exit and save the results. Reservoir Double click on the blue reservoir icon to enter the data for the reservoir. Select the Petroleum Experts Reservoir model on the left hand side, enter the PVT data for the reservoir and click on Input Data.
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In the Input Data section enter the reservoir parameters as shown in the next snapshot.
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Before proceeding, it is recommended to check the inputs by visualizing the sketch of the multilateral network. For this, select | Visualise | All and the following sketches appear:
| Analyse | Calculate to generate a composite IPR for both laterals: Select Curve as calculation option.
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The calculation is triggered by selecting the "Calculate" button. At the end of the calculation, the following IPR plot is displayed:
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Note: The IPR plot obtained is referenced at the Tie point and it considers the pressure drop across the down hole network of casings, tubings and chokes if the finite conductivity switch is activated. In other words, the IPR curve represents the relationship between the gas flow rate and the Tie Point Pressure. The IPR plot curve is calculated for 20 values of pressure with the corresponding 20 values of rate. In this IPR plot we can see that at very high flow rates (close to the AOF) the IPR curve goes backwards. The reason for this behavior can be explained by the fact that at low Tie Point Pressures, the expansion of the gas in the wellbore causes high gas velocities that, on their turn, produce high pressure drops along the well. The higher pressure drops cause a reduction in the production itself, therefore the "knee" in the curve. Usually this behaviour will not affect the performance of the well as the intersection of the VLP/IPR is rarely close to the AOF. Click Finish in the Plot. Click | Done | Finish and | Done to go the main section of PROSPER.
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3.1.6.5.6 Estimation of the well flow rate and inspecting the detailled results The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System (Ipr +Vlp) | 3 Variables. After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the downstream pressure of the system. Since here there is no pipeline included in this model, the top node pressure is the well head flow pressure. Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and | Calculate with the following results:
One can read a gas rate around 56 MMscf/d. If one select | Plot | System Plot, the system plot (VLP + IPR plot) is displayed as follow:
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Select | Finish to return to the previous screen:
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Now select | Solution details | Inflow Layer details. Here the rate and pressure distribution along each lateral is displayed:
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One can plot them with | Plot and select the variables of interest with | Variables.
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With | Done, the following plot is generated:
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The plot above shows pressure and rate distribution versus depth for both laterals.
3.1.7 Tutorial 07: Modelling a slanted oil well File: ~/samples/PROSPER/T07_SlantedOilWell.Out The main objectives of this example are to show: · How to set up a PROSPER model for a slanted oil well · How to enter basic black oil PVT data · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP.
3.1.7.1 Statement Of The Problem A slanted well is to be drilled to produce oil. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. It is required to: - Set-up a PROSPER well model for a slanted/ deviated oil well. - Estimate the initial oil rate against a well head flowing pressure of 250 psig
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3.1.7.2 PVT Input Data The basic available PVT data are: Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S): Bubble point pressure:
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None 2500 psig at 200 degF
3.1.7.3 System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment - Geothermal gradient and - Average heat capacities 3.1.7.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB an so on. The key thing is to describe all the equipment in the well in a manner that is consistent with the origin selected. The well head depth does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 2000 5000 9500
True Vertical Depth in ft 0 2000 4500 8000
3.1.7.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.7.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ... © 1990-2011 Petroleum Experts Limited
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Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 9000 Casing 9500
Internal ft diameter inches N/A 3.992 8.3
Roughness in inches
in Rate multiplier
N/A
N/A
0.0018 0.0018
1 1
3.1.7.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth. It is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft 0 9500
Static temperature in deg F 70 200
The overall heat transfer coefficient is 8 btu/h/ft2/F. Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. 3.1.7.3.5 Average Heat Capacities Here the default average heat capacities that will be used: Phase Oil: Gas: Water:
PROSPER Manual
Heat Capacity in btu/lb/F 0.53 0.51 1
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3.1.7.4 Reservoir Input Data
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Cut: Total GOR: Compaction Permeability Reduction model: Skin model:
Darcy / Wong-Clifford* 4000 psig 200 degF 0% 400 scf/stb No Enter skin by hand / WongClifford Relative Permeability correction: No Permeability: 150 mD Reservoir Thickness (True stratigraphic thickness) : 100 ft Drainage Area: 340 acres Well bore radius: 0.354 ft Dietz Shape Factor: 31.6 Formation vertical Formation Anisotropy: 0.1 (fraction) Local Vertical anisotropy: 0.1 (fraction) Horizontal length to reservoir edge: 2150 ft Vertical Depth To Top Of Reservoir (starting from origin 8000 ft of deviation survey): Perforation interval in measured depth: 9500 ft - 9800 ft Perforation depth in true vertical depth: 8000 ft - 8100 ft Mechanical skin: +5
This example uses the Wong-Clifford deviation and partial penetration skin model. Alternative models for slanted wells exist in PROSPER: the multilateral Inflow model developed by Petroleum Experts and the Cinco-Ley model, available in combination with the Karakas & Tariq skin model. 3.1.7.5 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Construct a PROSPER model for a slanted oil producing well - Use the PROSPER well model to estimate the flow rate against a WHFP of 250 psig 3.1.7.5.1 System Options Here, select | File | New if a PROSPER file is already open.Then select | Options | Options and make the following choices
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Fluid: Oil and Water
Select | Done to complete this step. 3.1.7.5.2 PVT data Input In order to enter the PVT data, simply select |PVT|Input Data and populate the screen as shown below:
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Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
870
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
Select | Done to complete this step. 3.1.7.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss if, for example, the computer crashes. To save a file, select | File | Save as ... Afterwards, browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file.
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3.1.7.5.4 System Equipment Description In order to describe the system equipment (i.e. the hardware in and around the well bore), select | System | Equipment (Tubing etc) | All
Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.7.5.4.1 Deviation Survey
Here are the data available for this exercise:
Measured Depth in ft 0 2000 5000 9500
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points describing the well trajectory. For this, the | Filter button located on the top right of this screen is to be used. Select | Done and the screen labelled Surface Equipment will follow. 3.1.7.5.4.2 Surface Equipment
This model will not include any surface equipment.
Selecting the "Cancel" button located on the top left of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.7.5.4.3 Down Hole Equipment
The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) PROSPER Manual
Internal ft diameter inches N/A
Roughness in inches N/A
in Rate multiplier
N/A
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9000 9500
3.992 8.3
0.0018 0.0018
874
1 1
The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to use the top perforation as the reference depth for the static reservoir pressure. This implies that the down hole equipment description must stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.7.5.4.4 Geothermal gradient
The data available are:
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Measured Depth in ft 0 9500
Static temperature in deg F 70 200
The overall heat transfer coefficient is 8 btu/h/ft2/F.
Select | Done to proceed to the average heat capacity screen. PROSPER Manual
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3.1.7.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example
Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed:
3.1.7.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary and this appears:
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If one then selects | Draw Down hole this is the sketch of the well bore that appears:
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Select | Main to exit the screen.
3.1.7.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follow: IPR model selection
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Cut: Total GOR: Compaction Permeability Reduction model: Skin model: Relative Permeability correction:
Darcy / Wong-Clifford* 4000 psig 200 degF 0% 400 scf/stb No Enter skin by hand / WongClifford No
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To proceed, simply select the Input Data button in the top right corner of the screen above: IPR data entry Skin model: Relative Permeability correction: Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: Well bore radius:
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Enter skin by hand / WongClifford No 150 mD 100 ft 340 acres 0.354 ft
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From the screen above, one can select the the tab "Mech/Geom Skin" at the bottom left corner of the screen in order to enter the mechanical skin: IPR : Skin value entry and here one MUST enable the Wong-Clifford model!
Mechanical skin:
+5
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Now select the Dev/PP Skin tab at the bottom of the screen to enter the data pertinent to the Wong-Clifford model. Wong-Clifford parameters for deviation and partial penetration skin
Reservoir Thickness (True stratigraphic thickness) : 100 ft Well bore radius: 0.354 ft Drainage Area: 340 acres Dietz shape Factor: 31.6 Formation vertical Formation Anisotropy: 0.1 (fraction) Local Vertical anisotropy: 0.1 (fraction) Horizontal length to reservoir edge: 2150 ft Vertical Depth To Top Of Reservoir (starting from origin 8000 ft of deviation survey): Perforation interval in measured depth: 9500 ft - 9800 ft Perforation depth in true vertical depth: 8000 ft - 8100 ft Mechanical skin: +5
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This means that over a true vertical net distance of 100 ft, the perforated net interval along hole is 300 ft long. IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything make sense. For this, simply select | Calculate and the software will create and display the following plot:
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One can see that the deviation skin counter-balances the mechanical skin. In the end, an overall skin of less than 2 was achieved. Please select | Main and then save the PROSPER file with | File | Save to secure all changes made so far. 3.1.7.5.6 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System (Ipr + Vlp) | 3 Variables as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well either parameter may change. Therefore, this screen allows the user to sensitize both. When sensitizing on the water cut and /or the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified anywhere else. PROSPER Manual
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Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
If one selects | Plot | System Plot, the system plot (VLP + IPR plot) is displayed as follows:
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Select | Main to get back to the main PROSPER screen and save the file to secure all changes made. This completes this exercise.
3.1.8 Tutorial 08: Modelling a gas well with connected pipeline File: ~/samples/PROSPER/T08_GasWellwithSurfacePipeline.OUT The main objectives of this example are to show: · How to connect a surface pipe to a PROSPER well model · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP. 3.1.8.1 Statement Of The Problem In Tutorial 1, we have build a PROSPER model for a dry and wet gas well. The PROSPER file that corresponds to this tutorial is Tutorial_01.OUT. It is required to: - Connect a 5000 ft long pipeline (ID = 6 inches) to the well only model created in tutorial 1. - Predict the flow rate if the pressure at the manifold is 350 psig.
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3.1.8.2 Input Data In Tutorial 1, we have build a PROSPER model for a dry an wet gas well. The PROSPER file that corresponds to this tutorial is Tutorial_01.OUT. It is strongly suggested to work trough the tutorial 1 first in order to gain familiarity with the software. Users already familiar with the software can simply recall the file "Tutorial_01.OUT" and proceed with the current tutorial. The pipeline data are: Equipment
Length in ft
TVD in ft
ID in inches
Roughness in inches
Manifold
N/A
0
N/A
N/A
Pipeline
5000
0
6
0.0018
The surroundings of the surface pipeline are described with the following data: Temperature of the surroundings: 60 degF Overall Heat transfer coefficient at surface: 3 Btu/h/ft2/F. 3.1.8.3 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - construct a PROSPER model for a producing an oil well with surface pipeline included. - use the PROSPER well model to estimate the flow rate against a manifold pressure of 350 psig Step 1: Recall the file "Tutorial_01.OUT" and save it under a new name. Step 2: Describe the pipeline For this, select | System | Equipment | Surface Equipment and make the following changes:
Equipment
Length in ft
TVD in ft
ID in inches
Roughness in inches
Manifold
N/A
0
N/A
N/A
Pipeline
5000
0
6
0.0018
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Temperature of the surroundings: 60 degF Overall Heat transfer coefficient at surface: 3 Btu/h/ft2/F Select | Done | Done to complete this. Step 3: Select | Calculation | System | 3 Variables and make the following entries:
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Select | Continue | Continue | Calculate and this is what will be seen:
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One can read that the well would produce around 20 MMscf/d at a well head pressure of 395 psig. In order to visualise the system plot, select | Plot | System Plot and this is the plot that is generated:
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Select | Main and this completes this exercise.
3.1.9 Tutorial 09: Modelling a water injection well File: ~/samples/PROSPER/T09_WaterInjectionWell.OUT The main objectives of this example are to show: · How to set up a PROSPER model for a water injector · How to enter the PVT data · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well injection flow rate for a given WHFP. · How to generate and export lift curves to GAP/MBAL/REVEAL or any third party software (Eclipse, VIP, and so on)
3.1.9.1 Statement Of The Problem A well is to be drilled to inject water into a reservoir. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided.
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It is required to: - Estimate the initial flow rate against a well head flowing pressure of 1000 psig - Generate lift curves to be utilised by a simulator (REVEAL, GAP, MBAL, Eclipse, VIP, and so on.) 3.1.9.2 PVT Input Data The basic available PVT data are: Parameter Water salinity: Water temperature at the well head:
Value 8000 ppm 60 degF
3.1.9.3 System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment - Geothermal gradient and - Average heat capacities 3.1.9.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB and so on. The key thing is to describe all the equipment in the well in a consistent manner with respect to the origin selected. The well head depths does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 8000
True Vertical Depth in ft 0 8000
3.1.9.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.9.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves and so on.
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Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 7800 Casing 8000
Internal ft diameter inches N/A 3.992 8.3
Roughness in inches
894
in Rate multiplier
N/A
N/A
0.0018 0.0018
1 1
3.1.9.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth. It is the temperature gradient based upon the true vertical depth that is used during all the calculations.
Measured Depth in ft 0 8000
Static temperature in deg F 70 200
The overall heat transfer coefficient is 8 btu/h/ft2/F. The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. Note:
3.1.9.3.5 Average Heat Capacities Here the default average heat capacities will be used: Phase Oil: Gas: Water:
Heat Capacity in btu/lb/F 0.53 0.51 1
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3.1.9.4 Reservoir Input Data PROSPER has around 20 different inflow models for injection wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available.
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Cut: Total GOR: Compaction Permeability Reduction model: Relative Permeability: Reservoir Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Mechanical skin:
Darcy / Enter Skin by hand 4000 psig 200 degF 100 % 400 scf/stb No No 150 mD 100 ft 340 acres 31.6 0.354 ft +2
3.1.9.5 Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - construct a PROSPER model for a water injection well - use the PROSPER well model to estimate the water injection rate with an injection pressure of 1000 psig at the well head. 3.1.9.5.1 System Options Here, one simply select | File | New if a PROSPER file is already open, then select | Options | Options and make the following choices Fluid: Oil and Water Well type: Water Injector - NOT simply Injector.
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Select | Done to complete this step. 3.1.9.5.2 PVT data Input In order to enter the PVT data, select | PVT | Input Data and populate the screen as shown below:
Parameter Water salinity:
Value 8000 ppm
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Select | Done to complete this step. 3.1.9.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case for example the computer crashes. To save a file, simply select | File | Save as. Afterwards, browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file. 3.1.9.5.4 System Equipment Description The first step is to enter the injected fluid temperature of 60 degF at surface as shown in the screen shot below.
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In order to describe system equipment, select | System | Equipment (Tubing etc) | All. Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.9.5.4.1 Deviation Survey
Here are the data to enter:
Measured Depth in ft 0 8000
True Vertical Depth in ft 0 8000
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, use the | Filter button located on the top right of this screen. Select | Done and the next screen labelled Surface Equipment will follow. 3.1.9.5.4.2 Surface Equipment
This model will not include any surface equipment. Therefore, one simply need to select | Cancel to skip this step: PROSPER Manual
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Ensure that the ELF choke model is selected at the bottom left corner of the screen. Now select the "Cancel" button located on the top left of the screen and this will take the user to the next screen: the down hole equipment description screen. 3.1.9.5.4.3 Down Hole Equipment
The down hole equipment includes the tubings, casings, nipples, sub-surface safety valves, and so on. Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 7800 Casing 8000
Internal ft diameter inches N/A 3.992 8.3
Roughness in inches
in Rate multiplier
N/A
N/A
0.0018 0.0018
1 1
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The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This would mean that the down hole equipment description must stop at the top of the perforation. This is also true for multiple-zone completion because any pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.9.5.4.4 Geothermal gradient
The data available are:
Formation Measured Depth in ft 0 PROSPER Manual
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8000
902
200
The overall heat transfer coefficient is 8 btu/h/ft2/F.
Select | Done to proceed to the average heat capacity screen.
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3.1.9.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example
Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed. It is now possible to visualise a sketch of the well bore with | Summary | Draw Down hole. 3.1.9.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary to show the following:
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If one then selects | Draw Downhole this is the sketch of the well bore that appears:
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Select | Main to exit the screen.
3.1.9.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, select | System | Inflow Performance and make the appropriate choices as follows: IPR model selection IPR model: Darcy (Static) Reservoir Pressure: 4000 psig Reservoir Temperature: 200 degF Water Cut: 100 % Total GOR [NOT USED HERE - NEEDED 400 scf/stb FOR VALIDATION ONLY]: Compaction Permeability ReductionNo model: Skin model: Enter skin by hand
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To proceed, simply select the Input Data button in the top right corner of the screen above: IPR data entry Permeability: 150 mD Reservoir Thickness (True stratigraphic 100 ft thickness) : Drainage Area: 340 acres Dietz shape factor: 31.6 Well bore radius (Drill bit radius): 0.354 ft
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From the screen above, one can select the tab "Mech/Geom Skin" at the bottom left corner of the screen in order to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
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IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything make sense. For this, simply select | Calculate and the software will create and display the following plot:
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Note that the concept of AOF (Absolute Open Flow potential) does not apply to an injection well. The value displayed is simply the highest rate at which the IPR pressure was calculated. Please select | Main and then save the PROSPER file with | File | Save to secure all changes made so far. 3.1.9.5.6 Estimation of the well injection flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System (Ipr + Vlp) | 3 Variables as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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For an injection well, the top node pressure is the pressure upstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Geometric Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate. PROSPER Manual
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The well will inject around 10 000 stb of water per day with an an expected bottom hole flowing pressure of 4325 psig. Afterwards, select | Plot | System Plot to visualise the system plot:
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Select | Main to get back to the main PROSPER screen 3.1.9.5.7 Lift Curve generation for other applications
3.1.9.5.7.1 Introduction
Lift curves express the pressure drop across a tubing for a given set of variables. Different software providers use different formats and acronyms for lift curves. The most common acronyms are: - VLP for Vertical Lift Performance - TPD for Tubing Performance Data - TPC for Tubing Performance Curves - VFP for Vertical Flow Performance and so on. For water injection wells, the variables involved in lift curve generation are: - Liquid rate and - Well Head flowing pressure (= first node pressure) Recommendation: In this example, we will demonstrate how to generate lift curves with PROSPER since lift PROSPER Manual
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curves generation is a key task that PROSPER is used to perform. However, if a project involves the generation of lift curves for multiple wells, a more efficient approach would involve the use of GAP, the network modelling and optimisation tool developed by Petroleum Experts. Here are the reasons why: - GAP will instruct PROSPER to generate the lift curves using the very same PROSPER well model created by the user and linked to the well icon in GAP. - GAP will use PROSPER to generate and save lift curves for any number of wells in batch-mode. This can be done overnight for instance to save time. - GAP will ask for the right input variables depending upon the well type. The input variable selection for lift curves can sometime be delicate because different simulators use different names for the same quantity, for example some lift tables formats require the variable gas lift injection rate but other lift tables formats require the variable Gas Liquid Ration injected instead. 3.1.9.5.7.2 Steps
In order to generate wells' VLP, one first needs to work out the variables involved. Here these variables are liquid rates and WHFP. The second step is to choose values for the variables in such a manner that the host application (GAP, MBAL, REVEAL, Eclipse, ..) can reasonably interpolate between them to find the solution needed. Extrapolation and very large variable spacing are to be avoided. In this example, the following values will be used: · Liquid Rate: from 500 stb/d to 50 000 stb/d. · WHFP: from 500 psig to 5000 psig.
In order to enter the data for the lift curve generation , select | Calculation | VLP (Tubing Curves) | 3 Variables
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The next screen shot can be used to generate the range of rates to use. Use the | Generate button to automate the data entry:
The following rates values are generated wit | Done.
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A few notes: The values for top node pressure will be overwritten through the sensitivity variables. One shall make sure that the right VLP correlation is selected. Here, the Petroleum Experts 2 correlation will be used. The "User Selected" rate method gives control to the user to enter the rates he /she think will best describe the expected operating ranges of the well. One shall ensure that the first and last node are correctly selected.
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In order to proceed, select | Continue, select the relevant variables and populate the entries as per screen-shot below:
Now select | Continue to proceed. The lift curve calculation is triggered with | Continue | Calculate.
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Be patient. This might take a while! At the end, a message will confirm that the calculation has completed.
It is always good practice to plot and visualise the lift curve before exporting them. In this example, select | Plot to see the following:
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One can see that the lift curves all have the right shape and are smooth. One can return to the previous screen with | Finish. In order to export the lift curve,select the button "Export Lift Curve"
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The following screen appears where one has to select the format for the host application (in this case Schlumberger - Eclipse):
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The process is completed with | Continue | Save and the file is saved and loaded automatically for viewing: Select | File | Exit | Main to complete the exercise.
3.1.10 Tutorial 10: Modelling a gas injection well File: ~/samples/PROSPER/T10_GasInjectionWell.OUT The main objectives of this example are to show: · How to set up a PROSPER model for a gas injection well · How to enter the PVT data · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP. PROSPER Manual
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· How to generate and export lift curves to GAP/MBAL/REVEAL or any third party software (Eclipse, VIP, and so on.)
3.1.10.1Statement Of The Problem An well is to be drilled to inject gas into a reservoir. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. It is required to: - estimate the initial flow rate against a well head flowing pressure of 2500 psig - generate a well performance curve (Rate vs. well head flowing pressure) - generate lift curves to be utilised by a simulator (GAP, MBAL, REVEAL, Eclipse, VIP, ...) 3.1.10.2PVT Input Data The basic available PVT data are: Parameter Gas gravity: Separator pressure: Condensate to Gas Ratio: Condensate Gravity: Water to Gas Ratio: Water salinity: Impurities (H2S, CO2 & N2): Injection gas temperature at the well head:
Value 0.6 (Air = 1) 250 psig 0 stb/MMscf 50 API 0 stb/MMscf 10000 ppm 0% 60 degF
3.1.10.3System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment - Geothermal gradient and - Average heat capacities 3.1.10.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB and so on. The key thing is to describe all the equipment in the well in a manner consistent with © 1990-2011 Petroleum Experts Limited
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respect the origin selected. The well head depths does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 8000
True Vertical Depth in ft 0 8000
3.1.10.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.10.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type Xmas Tree (Well Head) Tubing Casing
Measured depth in ft (down to) 0
Internal diameter in inches N/A
7800 8000
3.992 8.3
Roughness in Rate multiplier inches N/A
N/A
0.0018 0.0018
1 1
3.1.10.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth and it is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft 0 8000
Static temperature in deg F 70 200
The overall heat transfer coefficient is 3 btu/h/ft2/F. Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection PROSPER Manual
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and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. 3.1.10.3.5 Average Heat Capacities Here the default average heat capacities will be used: Phase Oil: Gas: Water:
Heat Capacity in btu/lb/F 0.53 0.51 1
3.1.10.4Reservoir Input Data PROSPER has around 20 different inflow models for gas wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Condensate Gas Ratio: Compaction Permeability Reduction model: Reservoir Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since Production started: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor (D): Permeability entered: Mechanical skin:
Petroleum Experts / Enter Skin by hand 2000 psig 200 degF 0 stb/MMscf 0 stb/MMscf No 150 mD 100 ft 340 acres 31.6 0.354 ft 100 ft 10 days 25% 20% Calculated Total Permeability +5
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3.1.10.5Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - construct a PROSPER model for a producing water injection well - use the PROSPER well model to estimate the water injection with an injection pressure of 1000 psig at the well head. 3.1.10.5.1 System Options Here, one simply select | File | New if a PROSPER file is already open. Otherwise, simply select |Options|Options and make the following choices Fluid: Dry and Wet Gas Well type: Injector
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Select | Done to complete this step. 3.1.10.5.2 PVT data Input In order to enter the PVT data, simply select | PVT | Input Data and populate the screen as shown below:
Parameter Gas gravity: Separator pressure: Condensate to Gas Ratio: Condensate Gravity: Water to Gas Ratio: Water salinity: Impurities (H2S, CO2 & N2):
Value 0.6 (Air = 1) 250 psig 0 stb/MMscf 50 API 0 stb/MMscf 10000 ppm 0%
Select | Done to complete this step. 3.1.10.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes. To save a file, simply select | File | Save as ... Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file. © 1990-2011 Petroleum Experts Limited
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3.1.10.5.4 System Equipment Description In order to describe the hardware in / around the well bore (this is what the system equipment is), simply select | System | Equipment (Tubing etc) | All
Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.10.5.4.1 Deviation Survey
Here are the data:
Measured Depth in ft 0 8000
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True Vertical Depth in ft 0 8000
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, the | Filter button located on the top right of this screen is to be used. Select | Done and the next screen labelled Surface Equipment will follow. 3.1.10.5.4.2 Surface Equipment
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Selecting the "Cancel" button located on the top left of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.10.5.4.3 Down Hole Equipment
The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type Xmas Tree (Well Head) Tubing Casing
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Measured depth in ft (down to) 0
Internal diameter in inches N/A
7800 8000
3.992 8.3
Roughness in Rate multiplier inches N/A
N/A
0.0018 0.0018
1 1
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The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This would mean that the down hole equipment description shall stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.10.5.4.4 Geothermal gradient
The data available are:
Measured Depth in ft 0 8000
Static temperature in deg F 70 200
The overall heat transfer coefficient is 3 btu/h/ft2/F.
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Select | Done to proceed to the average heat capacity screen. 3.1.10.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example
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Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed. It is now possible to visualise a sketch of the well bore with | Summary | Draw Down hole. 3.1.10.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary. Afterwards, one then selects | Draw Down hole this is the sketch of the well bore that would appear:
Select | Main to exit the screen.
3.1.10.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follow:
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IPR model selection
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Condensate Gas Ratio: Compaction Permeability Reduction model:
Petroleum Experts / Enter Skin by hand 2000 psig 200 degF 0 stb/MMscf 0 stb/MMscf No
To proceed, simply select the Input Data button (red if invalid) in the top right corner of the screen above: IPR data entry
Reservoir Permeability: Reservoir Thickness (True stratigraphic thickness) : PROSPER Manual
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From the screen above, one can select the the tab "Mech/Geom Skin" at the bottom left corner of the screen in order to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
+5
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IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything make sense. For this, simply select | Calculate and the software will create and display the following plot:
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Note that the concept of AOF does not apply to an injection well. The values displayed corresponds to the highest rate for which the IPR pressure was computed. Please select | Main and then save the PROSPER file with | File | Save to secure all changes made so far. 3.1.10.5.6 Estimation of the well injection flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate. Afterwards, select | Plot to visualise the system plot:
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The well can inject around 70 MMscf/d. Select | Main to get back to the main PROSPER screen. This completes this exercise. 3.1.10.5.7 Lift Curve generation for gas injectors
3.1.10.5.7.1 Introduction
Lift curves express the pressure drop across a tubing for a given set of variables. Different software providers use different formats and acronyms for lift curves. The most common acronyms are: - VLP for Vertical Lift Performance - TPD for Tubing Performance Data - TPC for Tubing Performance Curves - VFP for Vertical Flow Performance and so on. For water injection wells, the variables involved in lift curve generation are: - Liquid rate and - Well Head flowing pressure (= first node pressure) Recommendation: In this example, we will demonstrate how to generate lift curves with PROSPER since lift PROSPER Manual
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curves generation is a key task that PROSPER is used to perform. However, if a project involves the generation of lift curves for multiple wells, a more efficient approach would involve the use of GAP, the network modelling and optimisation tool developed by Petroleum Experts. Here are the reasons why: - GAP will instruct PROSPER to generate the lift curves using the very same PROSPER well model created by the user and linked to the well icon in GAP. - GAP will use PROSPER to generate and save lift curves for any number of wells in batch-mode. This can be done overnight for instance to save time. - GAP will ask for the right input variables depending upon the well type. The input variable selection for lift curves can sometime be delicate because different simulators use different names for the same quantity. For example some lift tables formats require the variable gas lift injection rate but other lift tables formats require the variable Gas Liquid Ration injected instead. 3.1.10.5.7.2 Steps
In order to generate wells' VLP, one first needs to work out the variables involved. Here these variables are liquid rates and WHFP. The second step is to choose values for the variables in such a manner that the host application (GAP, MBAL, REVEAL, Eclipse, ..) can reasonably interpolate between them to find the solution needed. Extrapolation and very large variable spacing are to be avoided. In this example, the following values will be used: · Gas Rates: from 5 MMscf/d to 150 stb/d. · WHFP: from 1500 psig to 6000 psig.
In order to enter the data for the lift curve generation , select | Calculation | VLP (Tubing Curves) | 3 Variables
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The next screen shot can be used to generate the range of rates to use. Use the | Generate button to automate the data entry:
The following rates values are generated wit | Done.
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A few notes: The values for top node pressure will be overwritten through the sensitivity variables. The user must make sure that the right VLP correlation is selected. Here, the Petroleum Experts 2 correlation will be used. The "User Selected" rate method gives control to the user to enter the rates he /she think will best describe the expected operating ranges of the well. © 1990-2011 Petroleum Experts Limited
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The user must ensure that the first and last node are correctly selected.
In order to proceed, select | Continue, select the relevant variables and populate the entries as per screen-shot below:
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Now select | Continue to proceed.
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The lift curve calculation is triggered with | Continue | Calculate. Be patient. This might take a while! At the end, a message will confirm that the calculation has completed.
It is always good practice to plot and visualise the lift curve before exporting them. In this example, select | Plot to see the following:
One can see that the lift curves all have the right shape and are smooth. One can return to the previous screen with | Finish. In order to export the lift curve,select the button "Export Lift Curve"
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The following screen appears where one has to select the format for the host application (in this case Schlumberger - Eclipse):
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The process is completed with | Continue | Save and the file is saved and loaded automatically for viewing: Select | File | Exit | Main to complete the exercise.
3.1.11 Tutorial 11: Modelling a steam injection well File: ~/samples/PROSPER/T11_SteamInjectionWell.OUT The main objectives of this example are to show how to build a PROSPER well model for a steam injector.
3.1.11.1Statement Of The Problem An injection well is to be drilled to inject steam into an oil reservoir. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. PROSPER Manual
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It is required to estimate the initial flow rate against a well head flowing pressure of 1500 psig VLP's will be generated to illustrate the requirements for use in GAP for instance 3.1.11.2PVT Input Data The basic available PVT data are: Parameter Water salinity: Steam temperature at the well head:
Value 10 000 ppm 700 degF
3.1.11.3System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - deviation survey - surface equipment - down hole equipment - Geothermal gradient and - Average heat capacities 3.1.11.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB and so on. The key thing is to describe all the equipment in the well in a manner consistent with respect to the origin selected. The well head depth does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 2000
True Vertical Depth in ft 0 2000
3.1.11.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.11.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ... © 1990-2011 Petroleum Experts Limited
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Equipment type Xmas Tree (Well Head) Tubing Casing
Measured depth in ft (down to) 0
Internal diameter in inches N/A
1800 2000
4.0 8.3
Roughness in Rate multiplier inches N/A
N/A
0.0006 0.0006
1 1
3.1.11.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth and it is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft
True Vertical Depth in ft
Static Temperature in ft
Heat Transfer coefficient in btu/ h/ft2/F
0
0
70
8
2000
2000
130
8
Air temperature: 70 degF Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. 3.1.11.4Reservoir Input Data PROSPER currently has nearly 20 different inflow models for water / steam injection wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
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Static Reservoir Pressure: 1000 psig Reservoir Temperature: 130 degF Water Cut: 100 % Total GOR: 0 scf/stb Compaction Permeability No Reduction model: Productivity Index: 100 stb/d/psi
3.1.11.5Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - construct a PROSPER model for a producing steam / water injection well - use the PROSPER well model to estimate the water injection with an injection pressure of 1500 psig at the well head. 3.1.11.5.1 System Options Launch PROSPER and select | Options |Options and make the following choices Fluid: Oil and Water Well type: Water Injector and NOT Injector! Model: Improved Approximation Steam Calculation: Allow Steam Calculations
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In order to model approximation.
steam, one must choose enthalpy balance or improved
Select | Done to complete this step. 3.1.11.5.2 PVT data Input In order to enter the PVT data, simply select | PVT | Input Data and populate the screen as shown below: The basic available PVT data are: Parameter Water salinity: Steam temperature at the well head:
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Value 10 000 ppm 700 degF
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Select | Done to complete this step. 3.1.11.5.3 System Equipment Description First select | System | Equipment and enter the steam injection temperature of 700 degF.
Now select | All | Edit and this takes to the deviation survey screen: © 1990-2011 Petroleum Experts Limited
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Now select | Done to enter the surface equipment:
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Here the only input required is the air temperature of 70 degF. Select | Done to advance to the down hole equipment screen:
Equipment type
Measured depth in (down to) Xmas Tree (Well 0 Head) Tubing 1800 Casing 2000
Internal ft diameter inches N/A 4.0 8.3
Roughness in inches
in Rate multiplier
N/A
N/A
0.0006 0.0006
1 1
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Select | Done to enter the temperature data:
Measured Depth in ft
True Vertical Depth in ft
Static Temperature in ft
Heat Transfer coefficient in btu/ h/ft2/F
0
0
70
8
2000
2000
130
8
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Finally select | Done | Done and save the file to secure the data entry.
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3.1.11.5.4 IPR Data For the IPR data, select | System | Inflow Performance and make the following selections / entries: IPR model: PI Entry Static Reservoir Pressure: 1000 psig Reservoir Temperature: 130 degF Water Cut: 100 % Total GOR: 0 scf/stb Compaction Permeability No Reduction model: Productivity Index: 100 stb/d/psi
Now select the Input Data tab and enter the productivity index of 100 stb/d/psi:
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The following IPR curve is generated and displayed if one selects | Calculate:
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Select | Main to complete the data entry. 3.1.11.5.5 Estimation of the well injection flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure of 1500 psig as per screen-shot below:
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Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: User Selected - Generate:
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First Value: 100 Number: 20 Increment: 500 Select | Generate to populate the rate cells:
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Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate. Afterwards, select | Plot to visualize the system plot:
Details of the calculations can be inspected by selecting | Finish | Sensitivity PvD | Contine | Calculate:
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The steam properties (quality, density, viscosity, enthalpy and so on) can be visualized by scrolling this table to the right:
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Select | Main to get back to the main PROSPER screen. This completes this exercise.
3.1.12 Lift Curve Generation for Steam Injectors 3.1.12.1Introduction Lift curves express the pressure drop across a tubing for a given set of variables. Different software providers use different formats and acronyms for lift curves. The most common acronyms are: - VLP for Vertical Lift Performance - TPD for Tubing Performance Data - TPC for Tubing Performance Curves - VFP for Vertical Flow Performance and so on. For water injection wells, the variables involved in lift curve generation are: - Liquid rate and - Well Head flowing pressure (= first node pressure)
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Recommendation: In this example, we will demonstrate how to generate lift curves with PROSPER since lift curves generation is a key task that PROSPER is used to perform. However, if a project involves the generation of lift curves for multiple wells, a more efficient approach would involve the use of GAP, the network modelling and optimisation tool developed by Petroleum Experts. Here are the reasons why: - GAP will instruct PROSPER to generate the lift curves using the very same PROSPER well model created by the user and linked to the well icon in GAP. - GAP will use PROSPER to generate and save lift curves for any number of wells in batch-mode. This can be done overnight for instance to save time. - GAP will ask for the right input variables depending upon the well type. The input variable selection for lift curves can sometime be delicate because different simulators use different names for the same quantity. For example some lift tables formats require the variable gas lift injection rate but other lift tables formats require the variable Gas Liquid Ration injected instead. 3.1.12.2Steps In order to generate wells' VLP, one first needs to work out the variables involved. Here these variables are liquid rates and injected fluid temperature(IFT). The second step is to choose values for the variables in such a manner that the host application (GAP, MBAL, REVEAL, Eclipse, ..) can reasonably interpolate between them to find the solution needed. Extrapolation and very large variable spacing are to be avoided. In this example, the following values will be used: · Liquid Rates: from 100stb/d to 9600stb/d. · IFT: from 450 deg F to 800 deg F. 3.1.12.3PROSPER Preference Settings To ensure smooth VLP profiles, the calculation step length will be changed to 5-ft. Reducing the calculation step length ensures that the steam phase change due to pressure and temperature changes in the wellbore will be captured and will serve to produce smooth VLP profiles. To change the calculation step length, from the PROSPER main menu select: FIle | Preferences | Limits
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Enter the the following data: Calculation Step Length
5-FT
Use Correlation Step Length
Yes
Select Done NOTE: It is important that the above preference limits are set back to default once the VLP has been generated. 3.1.12.4Data Entry for Lift Curve Generation To enter the data for the lift curve generation , select: Calculation | VLP (Tubing Curves) | 3 Variables
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The next screen shot can be used to generate the range of rates to use. Use the Generate button to automate the data entry: The following rate values ranging from 100stb/d to 9600stb/d are generated using Step Increment of 500 and 20 spaces.
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A few notes: The values for top node pressure and injected fluid temperature will be overwritten through the sensitivity variables. The "User Selected" rate method gives control to the user to enter the rates he /she think will best describe the expected operating ranges of the well. The user must ensure that the first and last node are correctly selected. In order to proceed, select | Continue, select the relevant variables and populate the entries as per screen-shot below: PROSPER Manual
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Now select | Continue to proceed. 3.1.12.5Lift Curve Inspection It is always good practice to plot and visualize the lift curve before exporting them. In this example, select | Plot to see the following:
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One can see that the lift curves all have the right shape and are smooth. One can return to the previous screen with | Finish. 3.1.12.6Lift Curve Export In order to export the lift curve,select the button "Export Lift Curve"
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The following screen appears where one has to select the format for the host application (in this case Schlumberger - Eclipse):
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The process is completed with | Continue | Save and the file is saved and loaded automatically for viewing: Select | File | Exit | Main to complete the exercise.
3.1.13 Tutorial 12: Modelling an oil well with gravel pack File: ~/samples/PROSPER/T12_GravelPackedOilWell.OUT 3.1.13.1Pre-requisite and Statement Of The Problem The main objective of this example is to show how to build a PROSPER model for a gravel packed well. This example is built on the tutorial 2. Therefore, it is recommended for the beginner to go through the tutorial 2 first before solving this example.
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3.1.13.2Gravel Pack Data The following gravel pack parameters are available Parameter Gravel Pack Permeability: Perforation diameter: Shot density: Gravel Pack length: Perforation Interval: Perforation efficiency: Beta Factor: DP Gravel Pack Calculation Method:
Value 35 000 mD 1 inch 6 shots per feet 2 inches 100 ft 50% Calculated Multiphase
3.1.13.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Activate the gravel pack option in PROSPER - Describe the gravel pack in the IPR section - Estimate the well flow rate against a given well head flowing pressure 3.1.13.3.1 System Options Open the PROSPER file created for tutorial 2 (Tutorial_02.out). Select | Options | Options and make the following choices: Sand Control: Gravel Pack
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Note that one can change the well completion type to "Open Hole" to model an open hole gravel pack option. Select | Done to complete this step. 3.1.13.3.2 Inflow Performance Relation (IPR) The gravel pack affects the Inflow Performance Relation. Therefore, select | System | Inflow Performance | Input Data | Sand Control and make the following entries: IPR : Sand Control Data
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Parameter Gravel Pack Permeability: Perforation diameter: Shot density: Gravel Pack length: Perforation Interval: Perforation efficiency: Beta Factor: DP Gravel Pack Calculation Method:
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Value 35 000 mD 1 inch 6 shots per feet 2 inches 100 ft 50% Calculated Multiphase
Select the Sand Control tab for the description of the gravel pack.
IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything make sense. For this, simply select | Calculate and the software will create and display the following plot:
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To superimpose the plots of the skins and associated dP , select |Variables | Set | Done and the plot is up-dated as follow:
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One can also visualise the numerical values behind the plots with | Results:
Please select | Main and then save the PROSPER file with | File | Save to secure all changes made. 3.1.13.3.3 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well either parameter may change. Therefore, this screen allow to sensitize both. When sensitizing on the water cut or / and the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified anywhere else. Surface Equipment Correlation: This applies to any pipeline in the model. Since this © 1990-2011 Petroleum Experts Limited
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model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
Note that PROSPER displays under solution details, the total skin, the dP due to sand control, the sand control skin and the velocity of the fluid at the casing (Vc). With | Plot | System Plot, the following VLP + IPR plot is generated:
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Note: The lower curve on this plot represents the pressure drop across the gravel pack completion. Select | Main to exit the screen. This completes this tutorial.
3.1.14 Tutorial 13: Modelling a frac and packed well File: ~/samples/PROSPER/T13_Frac&PackedOilWell.OUT 3.1.14.1Pre-requisite and Statement Of The Problem The main objective of this tutorial is to show how to build a PROSPER model for a hydraulically fractured and gravel packed well. This example is built on the tutorial 2. Therefore, it is recommended for the beginner to go through the tutorial 2 first before solving this example. 3.1.14.2Frac & Pack Data The following parameters are available Fracture Data
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Parameter Time: Reservoir Porosity: Fracture Height: Fracture Half-Length: Dimensionless Fracture Conductivity (FCD ): Fracture Face Skin:
Value 1 day 0.25 100 ft 30 ft 5000 0
Gravel Pack Data Parameter Gravel Pack Permeability: Perforation diameter: Shot density: Gravel Pack length: Perforation Interval: Perforation efficiency: Beta Factor: DP Gravel Pack Calculation Method:
Value 35 000 mD 1 inch 6 shots per feet 2 inches 100 ft 50% Calculated Multiphase
3.1.14.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Activate the gravel pack option in PROSPER - Activate the hydraulically fractured IPR model in PROSPER - Describe both the fracture and the gravel pack in the IPR section - Estimate the well flow rate against a given well head flowing pressure 3.1.14.3.1 System Options Open the PROSPER file created for tutorial 2 (Tutorial_02.out). Select | Options | Options and make the following choices: Sand Control: Gravel Pack
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Note that one can model an open hole completion by selecting the well completion type "Open Hole" on this screen. Select | Done to complete this step. 3.1.14.3.2 Inflow Performance Relation (IPR) The frac-pack completions affects the Inflow Performance Relation. Therefore, select | System | Inflow Performance | Input Data | Sand Control and make the following entries: Reservoir model: Hydraulically Fractured Well
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Select | Input Data to describe the fracture: Fracture Data Parameter Time: Reservoir Porosity: Fracture Height: Fracture Half-Length: Dimensionless Fracture Conductivity (FCD ):
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Select the tab "Mech / Geom Skin" to enter the fracture face skin Fracture Face Skin Parameter Fracture Face Skin:
Value 0
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Note: The fracture face skin cannot be negative!
In order to describe the pack data, select | "Sand Control" and make the following entries: Sand Control Data Parameter Gravel Pack Permeability: Perforation diameter: Shot density: Gravel Pack length: Perforation Interval: Perforation efficiency: Beta Factor: DP Gravel Pack Calculation Method:
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Value 35 000 mD 1 inch 6 shots per feet 2 inches 100 ft 50% Calculated Multiphase
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In order to generate an IPR, select | Calculate:
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Details of the inflow results can be accessed by selecting | Results:
Now, select | Main and then save the PROSPER file with | File | Save to secure all changes made. 3.1.14.3.3 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well any of these two parameters may change. Therefore, this screen allow to sensitize both. When sensitizing on the water cut or / and the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified anywhere else. Surface Equipment Correlation: This applies to any pipeline in the model. Since this PROSPER Manual
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model does not include any pipeline, the choice of any pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
Note that PROSPER displays under solution details, the total skin, the dP due to sand control and the sand control skin. The system plot can be generated with | Plot | System:
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Note: The lower curve on the system plot represents the pressure drop across the gravel pack completion. Select | Main to exit this screen. This completes this tutorial.
3.1.15 Tutorial 14: Modelling a well with Pre-Packed Screen File: ~/samples/PROSPER/T14_OilWellwithPre-PackedScreen.OUT 3.1.15.1Pre-requisite and Statement Of The Problem The main objective of this tutorial is to show how to build a PROSPER model for a well completed with wire wrapped screen. This example is built on the tutorial 2. Therefore, it is recommended for the beginner to go through the tutorial 2 first before solving this example. 3.1.15.2Pre-packed Screen Data The following parameters are available for the pre-packed screens:
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Parameter Value Screen Inner Radius: 0.3 ft Screen Outer Radius: 0.33 ft Screen Permeability: 50 000 mD Slot Width: 0.02 inches Screen Turbulence Factor: Calculated Screen Outside Permeability: 50 000 mD Screen Outside Turbulence factor Calculated (Beta):
3.1.15.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Activate the Pre-Packed screen option in PROSPER - Describe the Pre-Packed in the IPR section - Estimate the well flow rate against a given well head flowing pressure 3.1.15.3.1 System Options Open the PROSPER file created for tutorial 2 (Tutorial_02.out). Select | Options | Options and make the following choices: Well Completion Type: Open Hole Sand Control: Pre-Packed Screen
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Note that one simply need to change the well completion type to "Cased Hole" to model an open hole completion. Select | Done to complete this step. 3.1.15.3.2 Inflow Performance Relation (IPR) The completion type "pre-packed screen" affects primarily the Inflow Performance Relation. Therefore, select | System | Inflow Performance | Input Data | Sand Control and make the changes described below: Select | System | Inflow Performance | Input Data | Sand Control and make the following entries: Data for the completion type "Pre-Packed Screen"
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Parameter Value Perforation intervall: 100 ft Screen Inner Radius: 0.3 ft Screen Outer Radius: 0.33 ft Screen Permeability: 50 000 mD Slot Width: 0.02 inches Screen Turbulence Factor: Leave Blank and Prosper calculates it Screen Outside Permeability: 50 000 mD Screen Outside Turbulence factor Leave Blank and Prosper calculates it (Beta):
In order to generate an IPR plot select | Calculate and the well inflow is generated as follow:
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Select | Main and then save the PROSPER file with | File | Save to secure all changes made. 3.1.15.3.3 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well either parameter may change. Therefore, this screen allow to sensitize both. When sensitizing on the water cut or / and the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified anywhere else. Surface Equipment Correlation: This applies to any pipeline in the model. Since this PROSPER Manual
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model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
Note that PROSPER displays under solution details, the total skin, the dP due to sand control and the sand control skin. To visualise the IPR-VLP plot select | Plot | System Plot and the following plot is generated:
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Select | Main to exit the screen. This step completes this exercise.
3.1.16 Tutorial 15: Modelling a well with slotted liners File: ~/samples/PROSPER/T15_OilWellwithslottedLiner.OUT 3.1.16.1Pre-requisite and Statement Of The Problem The main objective of this tutorial is to show how to build a PROSPER model for a well completed with wire wrapped screen. This example is built on the tutorial 2. Therefore, it is recommended for the beginner to go through the tutorial 2 first before solving this example. 3.1.16.2Slotted Liner Data The following liner parameters are available
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Parameter Liner Inner Radius: Liner Outer Radius: Slot height: Slot Width: Slot Density: Outer Screen thickness: Liner Outside Permeability: Liner Outside Turbulence factor (Beta):
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Value 0.3 ft 0.34 ft 4 inches 0.01 inches 3 slots per feet does not apply - 0 ft 50 000 mD does not apply - 0 ft
3.1.16.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Activate the slotted liner option in PROSPER - Describe the slotted liner in the IPR section - Generate an IPR plot - Estimate the well flow rate against as given well head flowing pressure 3.1.16.3.1 System Options Open the PROSPER file created for tutorial 2 (Tutorial_02.out). Select | Options | Options and make the following choices: Well Completion Type: Open Hole Sand Control: Slotted Liner
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Select | Done to complete this step. 3.1.16.3.2 Inflow Performance Relation (IPR) The completion type "slotted liner" affects primarily the Inflow Performance Relation. Therefore, select | System | Inflow Performance | Input Data | Sand Control and make the changes described below:
Parameter Production interval Liner Inner Radius: Liner Outer Radius: Slot height: Slot Width: Slot Density: Outer Screen thickness: Liner Outside Permeability: Liner Outside Turbulence factor (Beta):
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Value 100 ft 0.3 ft 0.34 ft 4 inches 0.01 inches 3 slots per feet does not apply - 0 ft 50 000 mD does not apply - 0 ft
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To proceed, simply select the | Calculate and the IPR is generated with rate dependent skin due to the slotted liner included:
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Please select | Main and then save the PROSPER file with | File | Save to secure all changes made so far. 3.1.16.3.3 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well any of these two parameters may change. Therefore, this screen allow to sensitize both. When sensitizing on the water cut or / and the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified anywhere else. Surface Equipment Correlation: This applies to any pipeline in the model. Since this PROSPER Manual
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model does not include any pipeline, the choice of any pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
Note that PROSPER displays under solution details, the total skin, the dP due to sand control and the sand control skin. All the sensitivity possibilities previously available remain. PROSPER also the gravel pack parameters as sensitivity variables.
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This completes this exercise.
3.1.17 Tutorial 16: Modelling a well with Wire Wrapped Screen File: ~/samples/PROSPER/T16_OilWellwithWireWrappedScreens.OUT 3.1.17.1Pre-requisite and Statement Of The Problem The main objective of this tutorial is to show how to build a PROSPER model for a well completed with wire wrapped screen. This example is built on the tutorial 2. Therefore, it is recommended for the beginner to go through the tutorial 2 first before solving this example. 3.1.17.2Wire Wrapped Screen Data The following wire wrapped parameters are available Parameter Screen Outer Radius: Screen Permeability: Liner Outside Turbulence factor (Beta):
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Value 0.33 ft 50 000 mD Calculated
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3.1.17.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Activate the wire wrapped screen option in PROSPER - Describe the wire wrapped screen in the IPR section - Estimate the well flow rate against a given well head flowing pressure 3.1.17.3.1 System Options Open the Tutorial_02.OUT file, select | Options | Options and make the following choices Well Completion Type: Open Hole Sand Control: Wire Wrapped Screen
Select | Done to complete this step.
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3.1.17.3.2 Inflow Performance Relation (IPR) The completion type "Wire-Wrapped Screen" affects primarily the Inflow Performance Relation. Therefore, select | System | Inflow Performance | Input Data | Sand Control and make the changes described below:
Parameter Perforation interval: Screen Outer Radius: Screen Permeability: Liner Outside Turbulence factor (Beta):
Value 100 ft 0.33 ft 50 000 mD Calculated
IPR : Generating an IPR plot Once the sand control data input have been entered, it is a good practice to create an IPR plot to verify that everything make sense. For this, simply select | Calculate and the software will create and display the following plot: PROSPER Manual
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Please select | Main and then save the PROSPER file with | File | Save to secure all changes made. 3.1.17.3.3 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. The parameters Water Cut and GOR were entered earlier on the IPR screen. For the fluid description, there was also a need to enter the GOR on the PVT screen. However, during the life of a well either parameter may change. Therefore, this screen allow to sensitize both. When sensitizing on the water cut or / and the GOR, PROSPER will use the new sensitivity values for the calculations It will no longer use the GOR and the water cut values entered on the IPR screen or the GOR from the PVT screen. The same principle applies to all sensitivity variables specified anywhere else. Surface Equipment Correlation: This applies to any pipeline in the model. Since this © 1990-2011 Petroleum Experts Limited
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model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
Note that PROSPER displays under solution details, the total skin, the dP due to sand control and the sand control skin. To visualize the system plot, select | Plot | System Plot and the following plot is generated:
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Select | Main to get back to the main PROSPER screen. This completes this exercise.
3.1.18 Tutorial 17: Fully compostional well model for retrograde condenssate File: ~/samples/PROSPER/T17_CompostionalCondensateWell.OUT The main objectives of this example are to show: · How to set up a fully compositional PROSPER model for a retrograde condensate fluid · How to import a PRP file into PROSPER · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP.
3.1.18.1Statement Of The Problem A well is to be drilled to deplete a retrograde condensate reservoir. Compositional Fluid data (PVT), reservoir data (IPR) and down hole equipment © 1990-2011 Petroleum Experts Limited
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description (VLP) are provided. It is required to: - Build a fully compositional PROSPER well model - Use the model to estimate the initial flow rate against a well head flowing pressure of 2500 psig. 3.1.18.2PVT Input Data Here are the steps to follow: - Obtain a lab PVT report, - Carefully calibrate the lab data using an Equation Of State package like Petroleum Experts' PVTp - Generate a *.PRP file. Please refer to the PVTp User guide for more details about the steps required to generate a calibrated Equation Of State model for any type of hydrocarbon system. A PRP file is the generic EOS file format recognised by all PETEX' applications and looks like this:
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3.1.18.3System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment - Down hole equipment - Geothermal gradient and - Average heat capacities 3.1.18.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB an so on. The key thing is to describe all the equipment in the well in a manner consistent with the origin selected. The well head depths does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 12000
True Vertical Depth in ft 0 12000
3.1.18.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.18.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 11800 Casing 12000
Internal ft diameter inches N/A 3.992 8.3
Roughness in inches
in Rate multiplier
N/A
N/A
0.0018 0.0018
1 1
3.1.18.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the © 1990-2011 Petroleum Experts Limited
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measured depth into true vertical depth and it is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft 0 12000
Static temperature in deg F 70 274
The overall heat transfer coefficient is 5 btu/h/ft2/F. The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place inside and around the wellbore: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. Note:
3.1.18.3.5 Average Heat Capacities For this tutorial the default average heat capacities will be used: Phase Oil: Gas: Water:
Heat Capacity in btu/lb/F 0.53 0.51 1
3.1.18.4Reservoir Input Data PROSPER has more than 20 different inflow models for retrograde condensate producing wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Total GOR: Compaction Permeability Reduction model: Rervoir Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: PROSPER Manual
Petroleum Experts / Enter Skin by hand 6000 psig 274 degF 0 stb/MMscf 6943.98 scf/stb No 25 mD 100 ft 340 acres May, 2011
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Dietz shape factor: Well bore radius (Drill bit radius): Perforation Interval: Time since production: Reservoir Porosity: Connate water saturation: Non-Darcy Flow Factor (D): Permeability Entered: Mechanical skin:
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31.6 0.354 ft 100 ft 1 day 0.25 (fraction) 0.2 (fraction Calculated Total Permeability +5
3.1.18.5Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Construct a fully compositional PROSPER model for a producing retrograde condensate well - Use the PROSPER well model to estimate the flow rate against a WHFP of 2500 psig. 3.1.18.5.1 System Options Here, one simply select | File | New if a PROSPER file is already open. Otherwise, simply select |Options|Options and make the following choices Fluid: Retrograde Condensate Method: Equation Of State
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Now select | EOS Set-up and make the following changes: EOS model: Peng Robinson Optimisation Mode: Medium Optimise Repeat Calculation: Yes Volume Shift / Full Composition: Yes Reference Temperature: 60 degF Reference Pressure: 0 psig Phase detection method: Advanced Separator Stage 1 2
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Separator pressure (psig) 500 0
Separator temperature (deg F) 80 60
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Select | OK | Done to complete this step. 3.1.18.5.2 PVT data Input In order to enter the PVT data, simply select |PVT|Input Data | Import the *.PRP file and this is what can be seen:
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The PRP file for this tutorial is "Tutorial_17.prp".
It is required to enter the water salinity of 80 000 ppm at the bottom of the screen. One can generate and visualize the phase envelope with | Phase Env...| Plot and the following phase envelope is generated:
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Select | Exit | OK to return to the main PVT input screen.
Select | Done to complete this step. 3.1.18.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes for instance. To save a file, simply select | File | Save as. Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file. 3.1.18.5.4 System Equipment Description In order to describe the hardware in / around the well bore (this is what the system equipment is), simply select | System | Equipment (Tubing etc) | All
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Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.18.5.4.1 Deviation Survey
Here are the data:
Measured Depth in ft 0 12000
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True Vertical Depth in ft 0 12000
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, the | Filter button located on the top right of this screen is to be used. Select | Done and the next screen labelled Surface Equipment will follow. 3.1.18.5.4.2 Surface Equipment
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This will take the user to the next screen: the down hole equipment description screen. 3.1.18.5.4.3 Down Hole Equipment
The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 11800 Casing 12000
Internal ft diameter inches N/A 3.992 8.3
Roughness in inches
in Rate multiplier
N/A
N/A
0.0018 0.0018
1 1
The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. PROSPER Manual
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It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This would mean that the down hole equipment description shall stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.18.5.4.4 Geothermal gradient
The data available are:
Measured Depth in ft 0 12000
Static temperature in deg F 70 274
The overall heat transfer coefficient is 5 btu/h/ft2/F.
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Select | Done to proceed to the average heat capacity screen. 3.1.18.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example.
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Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed.
3.1.18.5.4.6 Equipment Summary
From the Equipment Data screen, one can generate a sketch of the well bore with | Summary and this is what would appear:
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If one then selects | Draw Down hole this is the sketch of the well bore that would appear:
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Select | Main to exit the screen.
3.1.18.5.4.7 Saving the PROSPER file
Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes. To save a file, simply select | File | Save and then simply answer YES to overwriting the file. 3.1.18.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follow: IPR model selection
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio:
Petroleum Experts / Enter Skin by hand 6000 psig 274 degF 0 stb/MMscf © 1990-2011 Petroleum Experts Limited
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Total GOR: 6943.98 scf/stb Compaction Permeability Reduction No model:
To proceed, simply select the Input Data button in the top right corner of the screen above: IPR data entry
Reservoir Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation Interval: Time since production: Reservoir Porosity: Connate water saturation: PROSPER Manual
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Non-Darcy Flow Factor (D): Permeability Entered:
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From the screen above, one can select the the tab "Mech/Geom Skin" at the bottom left corner of the screen in order to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
+5
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IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything make sense. For this, simply select | Calculate and the software will create and display the following plot:
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Select | Main and then save the PROSPER file with | File | Save to secure all changes made. 3.1.18.5.6 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
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The well can produce a gas rate of 51 MMscf/d. To visualize the system plot, select | Plot | System Plot:
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Select | Main to get back to the main PROSPER screen. This completes this tutorial.
3.1.19 Tutorial 18: Fully compostional CO2 injection well File: ~/samples/PROSPER/T18_CompostionalCO2Injector.OUT The main objectives of this example are to show: · How to set up a fully compositional PROSPER model for a CO2 injection well · How to import a PRP file into PROSPER · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well injection rate for a given WHFP.
3.1.19.1Statement Of The Problem A well is to be drilled to inject CO2 into a reservoir. Compositional Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided.
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It is required to to estimate the injection rate against a well head flowing pressure of 1000 psig. The CO2 has a temperature of 45 degF at surface. In order to better capture the thermodynamics of the CO2, It is required to to use a fully compositional model coupled with the improved rough approximation temperature model. 3.1.19.2PVT Input Data Using the PVTp software developed by Petroleum Experts, one can generate a PRP file to be used for this tutorial. The PRP file to be used for this specific tutorial is "Tutorial_18.PRP" A PRP file is the generic EOS file format recognised by all PETEX' applications. When edited, this is how the PRP file looks:
CO2 temperature at surface: 45 degF 3.1.19.3System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - Deviation survey - Surface equipment PROSPER Manual
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- Down hole equipment - Geothermal gradient data 3.1.19.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform or RKB. The key thing is to describe all the equipment in the well in a manner that is consistent with the origin selected. The well head depth does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 18000
True Vertical Depth in ft 0 18000
3.1.19.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.19.3.3 Down hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 1200 SSSV 1200 Tubing 17500 Casing 18000
Internal ft diameter inches N/A 3.992 3.8 3.992 8.5
Roughness in inches
in Rate multiplier
N/A
N/A
0.0006 N/A 0.0006 0.0006
1 1 1 1
3.1.19.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth and it is the temperature gradient based upon the true vertical depth that is used during the calculation. © 1990-2011 Petroleum Experts Limited
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Formation Depth ft 0 1200 18000
Measured Formation temperature degF 50 36 350
Heat Transfer coefficient Btu/h/ft2/F 3 3 3
The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. Note:
3.1.19.4Reservoir Input Data PROSPER has more than 20 different inflow models for gas wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
IPR model: Petroleum Experts / Enter Skin by hand Static Reservoir Pressure: 4500 psig Reservoir Temperature: 350 degF Water Gas Ratio: 0 stb/MMscf Total GOR: 1E6 scf/stb Compaction Permeability Reduction No model: Rervoir Permeability: 50 mD Reservoir Thickness (True 150 ft stratigraphic thickness) : Drainage Area: 340 acres Dietz shape factor: 31.6 Well bore radius (Drill bit radius): 0.354 ft Perforation Interval: 100 ft Time since production: 5 day Reservoir Porosity: 0.25 (fraction) Connate water saturation: 0.2 (fraction Non-Darcy Flow Factor (D): Calculated Permeability Entered: Total Permeability Mechanical skin: +10 PROSPER Manual
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3.1.19.5Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - construct a fully compositional PROSPER model for a producing retrograde condensate well - use the PROSPER well model to estimate the CO2 injection flow rate against a WHFP of 2500 psig 3.1.19.5.1 System Options Here, one simply select | File | New if a PROSPER file is already open. Otherwise, simply select | Options | Options and make the following choices Fluid: Retrograde Condensate Method: Equation Of State Well Type: Injector Calculation Type - Model: Improved Approximation
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Now select | EOS Set-up and make the following changes: EOS model: Peng Robinson Optimisation Mode: Medium Optimise Repeat Calculation: Yes Volume Shift / Full Composition: Yes Reference Temperature: 60 degF Reference Pressure: 0 psig Path to surface: Flash straight to stock tank Target GOR method: Use Separator Fluids
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Select | OK | Done to complete this step. 3.1.19.5.2 PVT data Input In order to enter the PVT data, simply select |PVT|Input Data | Import the file Tutorial_18.PRP file and this is what can be seen:
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Enter the reservoir temperature of 350 degF at the bottom of the screen. One can generate and visualize the phase envelope with | Phase Env...| Plot and the following phase envelope is generated:
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One may select | Exit | OK to return to the main PVT input screen. Select | Done to complete this step. 3.1.19.5.3 Saving the file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes. To save a file, simply select | File | Save as. Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file. 3.1.19.5.4 System Equipment Description In order to describe the hardware in / around the well bore (this is what the system equipment is), simply select | System | Equipment (Tubing etc) | All. First step here is to enter the injected fluid temperature of 45 degF.
Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.19.5.4.1 Deviation Survey
Here are the data:
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0 18000
0 18000
Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, the | Filter button located on the top right of this screen is to be used. PROSPER Manual
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Select | Done and the next screen labelled Surface Equipment will follow. 3.1.19.5.4.2 Surface Equipment
This model will not include any surface equipment. Therefore, one simply need to select | Cancel to skip this step: Selecting the "Cancel" button located on the top left of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.19.5.4.3 Down Hole Equipment
The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 1200 SSSV 1200 Tubing 17500 Casing 18000
Internal ft diameter inches N/A 3.992 3.8 3.992 8.5
Roughness in inches
in Rate multiplier
N/A
N/A
0.0006 N/A 0.0006 0.0006
1 1 1 1
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The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This would mean that the down hole equipment description shall stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.19.5.4.4 Geothermal gradient
The data available are:
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1200 18000
36 350
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3 3
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Select | Done to proceed to the equipment description screen. 3.1.19.5.4.5 Equipment Summary
Back on the equipment data screen, select | Summary to see a summary of all inputs:
Now select | Draw Down hole to see a sketch of the well bore.
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Select | Main to exit the screen.
3.1.19.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follow: IPR model selection
IPR model: Petroleum Experts / Enter Skin by hand Static Reservoir Pressure: 4500 psig Reservoir Temperature: 350 degF Water Gas Ratio: 0 stb/MMscf Total GOR: 1E6 scf/stb Compaction Permeability Reduction No model:
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To proceed, simply select the Input Data button in the top right corner of the screen above and make the following entries:
Rervoir Permeability: Reservoir Thickness (True stratigraphic thickness) : Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation Interval: Time since production: Reservoir Porosity: Connate water saturation: Non-Darcy Flow Factor (D): Permeability Entered: Mechanical skin:
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From the screen above, one can select the the tab "Mech/Geom Skin" at the bottom left corner of the screen in order to enter the mechanical skin: IPR : Skin value entry Mechanical skin:
+10
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IPR : Generating an IPR plot Once the IPR data input is completed, it is a good practice to create an IPR plot to verify that everything make sense. For this, select | Calculate and the software will create and display the following plot:
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Note: The concept of absolute open flow potential does not apply to injectors. The reported values simply corresponds to the highest rate for which an IPR pressure was computed. Please select | Main and then save the PROSPER file with | File | Save to secure all changes made so far. 3.1.19.5.6 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head (= Top Node here) injection pressure as per screen-shot below:
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Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of a pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic Geometric Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
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One can read a gas rate of 81 MMscf/d. If one selects | Plot | System Plot, the system plot (VLP + IPR plot) is displayed as follow:
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Select | Main to get back to the main PROSPER screen. This completes this tutorial.
3.1.20 Tutorial 19: Matching a dry gas well test File: ~/samples/PROSPER/T19_MatchingAGasWellTest.OUT The main objectives of this example are to show: · How to match a PROSPER gas well model to well test data · How to use the calibrated model to perform sensitivity runs on various variables 3.1.20.1Statement Of The Problem A PROSPER model for a dry and wet gas well was built in tutorial 1. After some production, the well has been tested. It is required to: - Analyse the well test results - Calibrate the PROSPER model to reproduce the well test results - Use the calibrated PROSPER model to study the impact of changing reservoir pressure change on the well performance.
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3.1.20.2Well Test data
Parameter Test date (optional): Test Comment (optional): Well Head Flowing Pressure: Flowing Tubing Head Temperature: Water Gas Ratio: Condensate Gas Ratio: Gas Flow Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation:
Value 01/01/2010 Main Flow Test 1000 psig 153 degF 5 stb/MMscf 5 stb/MMscf 15 MMscf/d 4500 ft 1920 psig top 2300 psig
3.1.20.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Recall the PROSPER model built in tutorial 1 (Tutorial_01.OUT) - Review the PROSPER model - Quality-check and calibrate the PROSPER model against the well test data - Select the appropriate VLP correlation - Superimpose the IPR curve to match the well test - Use the model to run sensitivity on Reservoir pressure 3.1.20.3.1 Open the PROSPER file Select | File | Open, locate and open the file "Tutorial_01.OUT" in the sample directory.
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3.1.20.3.2 Resetting any previous VLP matching This step is optional in this case but might be relevant in other cases where an inherited PROSPER file contains multiphase correlations that already have been calibrated. In order to reset the calibration parameters (Parameter 1 & Parameter 2), simply select | Matching | Correlation Parameters | Tubing and then select | Reset All.
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Select | Done to complete this step. 3.1.20.3.3 Matching - VLP /IPR Quality Check The general procedure in matching a well test can be broken in four (4) sequential steps: - First, critically review the well test results: are there in line with previous results? how reliable are the measurements? - Second, quality-check and calibrate the PVT. For dry gas and retrograde condensate wells, it is generally not required to perform a PVT matching. - Third, quality-check, select, calibrate and validate the VLP correlation against the actual tubing response - Fourth, find the IPR model / parameters that will reasonably reproduce the well test results.
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After completing the first step, proceed with the well test data entry. 3.1.20.3.3.1 Well Test Data Entry
In order to enter the well test data, select | Matching | Matching | VLP/IPR (QualityCheck) and populate the screen with the well test data given below:
Parameter Test date (optional): Test Comment (optional): Well Head Flowing Pressure: Flowing Tubing Head Temperature: Water Gas Ratio: Condensate Gas Ratio: Gas Flow Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation:
Value 01/01/2010 Main Flow Test 1000 psig 153 degF 5 stb/MMscf 5 stb/MMscf 15 MMscf/d 4500 ft 1920 psig top 2300 psig
The screen is divided into 3 sections: upper, middle and bottom. The upper section of the screen contains different buttons that can be categorized in two groups: the data processing buttons on the left and the task buttons on the right. The middle section contains the well test data and the bottom section of the screen contains in written form the recommended well test matching procedure In order to analyse a particular test, select this test point by clicking on the row number that starts at the beginning of each test entry, left of the column " Test Point Date". The selected test number then turns blue.
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We will primarily use the Task buttons located on the top right corner of the screen, from the left to the right to solve this well test matching exercise. 3.1.20.3.3.2 Estimate the U-value
In a design case, the U-value can be estimated using the full enthalpy balance model. Alternatively, when a well test is available, one can use the well test data to back calculate the overall heat transfer coefficient.This is what we are going to do next. For this simply select the task button "Estimate U Value" and the following message will appear:
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The program has estimated and displayed the heat transfer coefficient on the basis of the well test data. After selecting | OK, a message is displayed, proposing to replace the previous U-value in the model with this new one. With YES, the new U-value is taken as input for the model. The previous value is in fact overwritten. Here we will select YES and then the U-value is then transferred:
Select | OK to continue with the next task button, the "Correlation Comparison". 3.1.20.3.3.3 Correlation Comparison
It is well known that there is no universal multiphase correlation. Therefore, whenever a new well test is available for analysis, it is a good practice to perform a correlation comparison. The purposes of the correlation comparison are to: - Identify without bias which best reproduce the well test to be analyse - Quality check the well test results. For instance if none of the correlation came close to the well test, it might be worth checking the reliability of the well test data. To proceed, select the task button "Correlation Comparison" and then | OK | and here select a few correlations for comparison.
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Afterwards, select | Calculate | Calculate | Plot and this is what can be seen:
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One can zoom around the test point and this is what can be seen:
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Conclusion: One can see that the test point lies between Duns and Ros modified and the Petroleum Experts correlations. Select | Main to return to the VLP/IPR Matching screen to select the appropriate correlation based upon the matching parameters. 3.1.20.3.3.4 VLP matching
In order to perform the VLP matching select the task button "Match VLP" and the following screen would appear:
For the regression, select | Match and the regression routine will apply a gravity multiplier (Parameter 1) and a friction multiplier (Parameter 2) to each selected correlation in turn in order to match the well test. Ideally, both parameters should equal to unity and one can see here that both multipliers are very close indeed to unity. For more statistical details, select | Statistics to access this screen:
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The Petroleum Experts correlation 1, 2 and 3 require the least correction. We will proceed the analysis with Petroleum Experts 2. Therefore, reset all the matching for all the correlations except the Petroleum Experts 2 correlation.
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Now select | Done to return to the previous menu. 3.1.20.3.3.5 VLP / IPR matching
In order to perform the VLP/IPR matching, simply select the task button "VLP / IPR" and then unselect all correlations except PE2 and then select | Calculate:
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PROSPER computes VLP and IPR using the well test data as input. On the bottom right of the screen, the simulated solution rate and solution BHFP are displayed along with the test rate and test bottom hole flowing pressure. Note that "Test BHP" is the gauge pressure corrected to the well datum depth using the VLP correlation selected. With | Plot, this is what can be seen:
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One can read that the difference between measured and simulated parameters (rate and pressure) are both below 0.5%. The magnitude of this difference between simulated and actual data can be seen as acceptable. It can be concluded that the well test is valid and is properly calibrated. Should the match not be acceptable at this stage, then the error is confined to the IPR component because PVT and VLP have already been quality-checked, calibrated and validated. Select | Main and save the file to secure all changes made so far. 3.1.20.3.3.6 Performing Sensitivity runs
The table below lists the parameter combinations to be evaluated: Well head flowing pressure: CGR: WGR: Reservoir Pressure:
1000 psig 5 stb/MMscf 5 stb/MMscg 1500, 2000 & 2300 psig
In order to analyse the cases described above, one will perform sensitivity run on the parameters listed above. For this, select | Calculation | System |3 Variable and make the following choice: PROSPER Manual
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Note that the matched VLP correlation now appears with 2 numbers appended to it: the first number is the gravity multiplier (parameter 1) whereas the second number (parameter 2) is the friction multiplier. Now select | Continue and select the remaining sensitivity variables of interest: reservoir pressure and skin
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Now select | Continue | Calculate | OK and then | Plot | System Plot:
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An alternative way of plotting the results is now to select | Finish | Sensitivities and here select the variables of interest:
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This is how the plot of the gas rate versus reservoir pressure shows:
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Select | Main to return to the main menu of PROSPER. This completes this tutorial.
3.1.21 Tutorial 20: Matching a naturally flowing oil well test File: ~/samples/PROSPER/T20_MatchingAnOilWellTest.OUT The main objectives of this example are to show: · How to match a PROSPER naturally flowing oil well model to well test data · How to use the calibrated model to perform sensitivity runs on various variables: tubing size and reservoir pressure
3.1.21.1Statement Of The Problem A PROSPER model for a naturally flowing oil well was built in tutorial 2. After some production, the well has been tested and lab PVT data have been made available. It is required to: - Calibrate the PVT model against the lab data, - Analyse the well test results © 1990-2011 Petroleum Experts Limited
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- Calibrate the PROSPER model to reproduce the well test results - Use the calibrated model to study the impact of tubing size and reservoir pressure on the well performance. 3.1.21.2PVT Lab data & Well Test data PVT Data
Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S): Bubble point pressure:
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None 2500 psig at 200 degF
Further PVT data are given in tabular form below at 200 degF: Pressure in psig 1500 2000 2500 3000 4000
Gas Oil Ratio in scf/ Oil FVF in rb/stb stb 237 1.138 324 1.178 400 1.214 400 1.207 400 1.198
Oil Viscosity centipoises 1.34 1.15 1.01 1.05 1.11
in
Well test data Parameter Test date (optional): Test Comment (optional): Well Head Flowing Pressure: Flowing Tubing Head Temperature: Water Cut: Liquid Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation: Produced Gas-Oil Ratio:
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Value 01/01/2010 Main Flow Test 250 psig 158.5 degF 30% 8290 stb/d 7000 ft 2335 psig top 3800 psig 600 scf/stb
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3.1.21.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - recall the PROSPER model for the naturally producing oil well (see example 2) - Review the PROSPER model - Calibrate the black oil correlation against the lab PVT data and select the most suitable correlations for this crude - Quality-check and calibrate the PROSPER model against the well test data - Select the appropriate VLP correlation - Superimpose the IPR curve - Use the model to run sensitivity on tubing size and reservoir pressure. 3.1.21.3.1 Open the PROSPER file Select | File | Open, locate and open the file "Tutorial_02.OUT" in the sample directory.
3.1.21.3.2 Resetting any previous VLP matching This step is optional but might need consideration in cases where an inherited PROSPER file contains multiphase correlations that already have been calibrated. In order to reset the calibration parameters (Parameter 1 & Parameter 2), select | Matching | Correlation Parameters | Tubing and here one select | Reset All.
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Select | Done to complete this step. 3.1.21.3.3 PVT matching The PVT data accounts for more than 80% of the quality of a well model. Therefore, the PVT data need careful calibration. For this select | PVT | Input Data and here are the original surface data in the model: PVT Data
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Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S): Bubble point pressure:
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Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None 2500 psig at 200 degF
In order to calibrate the black oil correlations, one needs first to enter the PVT lab data. This is done with | Match Data and here one shall populate the screen as below: PVT Lab Data
Further PVT data are given in tabular form below at 200 degF: Pressure in psig
Gas Oil Ratio in scf/ Oil FVF in rb/stb stb
Oil Viscosity centipoises
in
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1500 2000 2500 3000 4000
237 324 400 400 400
1.138 1.178 1.214 1.207 1.198
1.34 1.15 1.01 1.05 1.11
Notes: - up to 50 tables with different temperatures can be entered here. - It is recommended to match the PVT at least at the the bubble point pressure with the corresponding oil formation volume factor and viscosity. PVT matching Select | Done to return to the PVT entry screen. Now select | Regression | Match All and then | OK | Parameters to view the results of the regression:
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Parameter 1 is a multiplier whereas Parameter 2 is a shift. Therefore the best correlation is the one with a parameter 1 equal to unity and parameter 2 equal to zero. For the oil FVF matching, Parameter 3 is the multiplier above the bubble point pressure whereas Parameter 4 is the shift above the bubble point pressure. Looking at the statistics above, we will select the Glaso black oil correlation for the bubble point calculation, solution GOR and oil formation volume. For the viscosity, the Petrosky correlation will be selected. Select | Done and | Done again to return to the PVT entry screen where the appropriate black correlations are selected:
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Now select | Done and save the file to secure all the changes made.
3.1.21.3.4 Matching - VLP /IPR Quality Check The general procedure in matching a well test can be broken in four (4) sequential steps: - First, critically review the well test results: are there in line with previous results? how reliable are the measurements? - Second, quality-check and calibrate the PVT. For dry gas and retrograde condensate wells, it is generally not required to perform any PVT matching. - Third, quality-check, select, calibrate and validate the VLP correlation against the actual tubing response - Fourth, find the IPR model / parameters that will reasonably reproduce the well test results. After completing the first step, proceed with the well test data entry.
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3.1.21.3.4.1 Well Test Data Entry
In order to enter the well test data, simply select | Matching | Matching | VLP/IPR (Quality-Check) and populate the screen as below: The screen is divided into 3 sections: upper, middle and bottom. The upper section of the screen contains different buttons that can be categorized in two groups: the data processing button on the left and the task buttons The middle section contains the well test data and the bottom section of the screen contains in written form a well test matching procedure that has been successfully tested over and over again. This is the recommended well test matching procedure. One can enter up 1000 well tests in this screen. After entering the well test data, one needs to select the test of interest for the analysis. To select a test, click on the row number that starts at the beginning of each test entry, left of the column " Test Point Date". The selected test number then turns blue. Well test data Parameter Test date (optional): Test Comment (optional): Well Head Flowing Pressure: Flowing Tubing Head Temperature: Water Cut: Liquid Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation: Produced Gas-Oil Ratio:
Value 01/01/2010 Main Flow Test 250 psig 158.5 degF 30% 8290 stb/d 7000 ft 2335 psig top 3800 psig 600 scf/stb
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Notes: - The approach to follow is documented at the bottom of the screen under"Matching Procedure". - For oil wells, always set the GOR free to 0 scf/stb and simply enter the total produced GOR in the Gas Oil Ratio column. PROSPER will use the PVT model to work out how much gas is free and how much gas is dissolved in the liquid phase at any P & T conditions. - We will use the Task buttons located on the top right corner of the screen, from the left to the right to solve this well test matching exercise. 3.1.21.3.4.2 Estimate the U-value
In a design case, the U-value can be estimated using the full enthalpy balance model. Because a well test is available, we will use the well test data to back calculate the overall heat transfer coefficient.This is what we are going to do next. For this simply select the task button "Estimate U Value" and the following message will appear:
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The program has estimated and displayed the heat transfer coefficient on the basis of the well test data selected. Under the assumption that the well test data are valid, select | OK and a message will appear, proposing to replace the previous U-value in the model with this new one.
With YES, the new U-value is taken as input for the model. The previous value is in fact overwritten. Here we will select YES and then the U-value is then transferred:
Select | OK to continue with the next task button, the "Correlation Comparison". 3.1.21.3.4.3 Correlation Comparison
It is well known that there is no universal multiphase correlation. Therefore, whenever a new well test is available for analysis, it is a good practice to perform a correlation comparison. The purposes of the correlation comparison are: - identify without bias which best reproduce the well test to be analyse - quality check the well test results. For instance if none of the correlation came close to © 1990-2011 Petroleum Experts Limited
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the well test, it might be worth checking the reliability of the well test data themselves. In most cases with oil wells, the Fancher-Brown correlation and the Duns & Ros modified multiphase correlation define the operating envelope of a tubing. Therefore, those 2 correlations will be selected along with a few generally reliable correlations like Petroleum Experts 2. To proceed, select the task button "Correlation Comparison" and then | OK | and here select a few correlations for comparison.
Afterwards, select | Calculate | Calculate | Plot and this is what can be seen:
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Conclusion: One can see that the test point lies outside of the solution envelope. This can happen for various reasons and it is the engineer's task to find out exactly what are the possible reasons behind this behaviour. In this particular case, we shall recall that the bubble pint pressure of the fluid at reservoir temperature is 2500 psig. The reservoir pressure is currently 3800 psig. This means that the oil is still undersaturated at reservoir conditions. Therefore the produced GOR must be equal to initial solution GOR of 400 scf/stb. Let us return with | Finish | done and correct the GOR to 400 scf/stb:
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Changing (i.e. correcting) the produced GOR will change the mass flow rate in the tubing and consequently change the heat loss in the surroundings of the well. Therefore, the U-value need to re-estimated and updated with | Estimate U Value | OK | Yes | OK. Now select | Correlation Comparison | OK | Calculate | Calculate | OK | Plot, this is how the gradient now looks like:
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Now one can clearly see that the test point has moved inside the solution envelope: between Fancher-Brown on the left and Duns & Ros Modified on the right. We can also see that the Petroleum Experts 2 correlation is very close to the test point. On the basis of this observation, we will select the Petroleum Experts 2 correlation moving forward. Select | Main to return to the VLP/IPR Matching screen to fine-tune the Petroleum Experts 2 correlation against the well test data. The emphasis here is fine-tune because a heavy correction is not desired. 3.1.21.3.4.4 VLP matching
Now select | Match VLP and select only the correlation of interest to proceed. Select | Match to trigger the non-linear regression that applies a gravity and a friction correction coefficient to the selected multiphase correlation. The parameter 1 is the gravity term multiplier whereas the parameter 2 is the friction term multiplier. Ideally, both should equal to unity and one can see here that both multipliers are very close indeed to unity.
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We can see in this example that both parameters are very close to unity: this means that the well test is consistent with model and that the selected multiphase correlation is suitable for this particular well. Now select | Done to return to the previous menu. 3.1.21.3.4.5 VLP / IPR matching
In order to perform the VLP/IPR matching, simply select the task button "VLP / IPR" and then | Calculate:
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PROSPER computes VLP and IPR using the well test data as input. On the bottom right of the screen, the simulated solution rate and solution BHFP are displayed along with the test rate and test bottom hole flowing pressure. Note that "Test BHP" is the gauge pressure corrected to the well datum depth using the VLP correlation selected. With | Plot, this is what can be seen:
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One can read that the difference between measured and simulated rate is only 0.2%, and for this case it can be considered that the rate difference between the measured and calculated rate is negligible. For most cases, the difference between the measured and calculated rate can be quite different. For those cases it will be necessary to change the IPR data i.e., reservoir pressure, permeability, skin, etc., until a suitable match has been achieved. To further illustrate the IPR tuning workflow, we shall consider the above match to be invalid, hence a decision will be made regarding the IPR data. Let us summarize: A well model is the combination of PVT, VLP and IPR. The PVT has been calibrated, The VLP also have been calibrated. Hence any error will be confined to the IPR. There are multiple IPR variables that can help conclude the exercise: reservoir pressure, permeability, skin, .... In the following, we will assume that the estimation of the reservoir pressure was not reliable. Hence, we will find the reservoir pressure required to match the well test. This can be done manually in iterative fashion or automatically. We will adjust the reservoir pressure automatically. For this, select | Finish | Done to get back to the well test data entry screen. Now select the task button "Adjust IPR" and the following screen will appear: PROSPER Manual
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Now select the well test of interest by checking "Test 1 on 01/01/2010 (Main Flow Test)" in the first column.
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Afterwards, select the button | Adjust Pres to access a new screen:
Now select | OK and a search algorithm will compute the reservoir pressure that will match the well test:
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One can read an adjusted reservoir pressure of 3726.56 psig. Now we will select | Done and then replace the static reservoir pressure on the test row:
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Now with the task button "VLP / IPR", and then | Calculate and | Plot this is how the match now looks like:
Clearly, we have achieve some improvements. Note: Changing the reservoir pressure to match a well test is not a general recommendation. The purpose of this example is to illustrate the use of this option. It is the engineer's task to decide which parameter needs to be altered to match an well test depending upon the specifics of the well test at hand. Select | Main and save the file to secure all changes made. 3.1.21.3.4.6 Performing Sensitivity runs
The table below contains the cases to be evaluated: Well head flowing pressure: water cut: GOR: Reservoir pressure: Tubing ID:
250 psig 30% 400 scf/stb 3000, 3500, 3800, 4000 & 4500 psig 2.441, 2.992, 3.992, 4.5 & 4.9 inches
In order to analyse the cases described above, one will perform sensitivity run on the parameters listed above. For this, select | Calculation | System |3 Variable and make PROSPER Manual
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the following choice:
Note that the matched VLP correlation now appears with 2 numbers appended to it: 1.00 and 0.97 The first number (1.00) is the gravity multiplier whereas the second number (0.97) is the friction multiplier. Now select | Continue and select the remaining sensitivity variables of interest: reservoir pressure and tubing ID
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One shall proceed with | Continue and a selection screen is displayed, which allows to define the section of the well the diameter changes applies to:
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Please select | Continue and | Calculate | OK and then | Plot | System Plot:
An alternative way of plotting the results is now to select | Finish | Sensitivities and here select the variables of interest:
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This is how the plot of the oil rate versus tubing internal diameter at various reservoir pressure looks like:
Note that one can change the scale with |Scale. PROSPER Manual
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This completes this tutorial.
3.1.22 Tutorial 21: Matching a water injection well test File: ~/samples/PROSPER/T21_MatchingAWaterInjectionWellTest.OUT The main objectives of this example are to show: · How to match a PROSPER naturally flowing oil well model to well test data · How to use the calibrated model to perform sensitivity runs on various variables
3.1.22.1Statement Of The Problem A PROSPER model for a gas injection well was built in tutorial 10. The injection well has been tested with surface pressure, injection rate and down hole pressure measurement. It is required to: - Recall the Tutorial_10.out PROSPER file - Analyse the well test results - Calibrate the PROSPER model to reproduce the well test results - Use the calibrated model to predict the injection rate when the reservoir pressure drops to 3000 psig and the well head pressure is 3500 psig and a reservoir temperature of 80 degF. 3.1.22.2Well Test data PVT Data For water injection well, the only PVT parameter required is simply the water salinity. PROSPER will then use correlation to compute the required fluid properties at different conditions. Well test data
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Parameter Test date (optional): Test Comment (optional): Well Head Flowing Pressure: Down hole Injection Temperature: Water Cut: Water Injection Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation: Gas-Oil Ratio [ Not Used]: GOR Free [ Not used]:
Value 01/01/2010 Main Flow Test 1250 psig 80 degF 100% 11000 stb/d 7500 ft 4350 psig top 3580 psig 0 scf/stb 0 scf/stb
3.1.22.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Recall the PROSPER model for the water injection well created in Tutorial 9 ( Tutorial_09.out) - Review the PROSPER model - Quality-check and calibrate the PROSPER model against the well test data - Select the appropriate VLP correlation - Superimpose the IPR curve - Use the model to run sensitivity injection pressure. 3.1.22.3.1 Open the PROSPER file Select | File | Open, locate and open the file "Tutorial_09.out" in the sample directory.
3.1.22.3.2 Resetting any previous VLP matching This step is optional but might be required when an inherited PROSPER file contains multiphase correlations that already have been calibrated. In order to reset the calibration parameters (Parameter 1 & Parameter 2), select | Matching | Correlation Parameters | Tubing and then select | Reset All
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Select | Done to complete this step. 3.1.22.3.3 PVT matching For water, PVT matching is not required. It is sufficient to input the water salinity and PROSPER will use a correlation to compute the water properties as function of temperature. It is also possible to account for the effect of pressure on the water viscosity. For this, it is needed to activate this feature under | Options | Options where one needs to select: Water Viscosity: Pressure Corrected Correlation.
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If comprehensive PVT properties for the injected water are available, then one can enter the data in the tables section of the PVT screen and PROSPER will use them. Caution is in order when using tables: the tables must cover all possible expected operation conditions of pressure and temperature! Now select | Done and save the file to secure all the changes made so far.
3.1.22.3.4 Matching - VLP /IPR Quality Check The general procedure in matching a well test can be broken in four (4) sequential steps: - First, critically review the well test results: are there in line with previous results? how reliable are the measurements? - Second, quality-check and calibrate the PVT. For water injection wells, it is not required to perform any PVT matching. - Third, quality-check, select, calibrate and validate the VLP correlation against the actual tubing response PROSPER Manual
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- Fourth, find the IPR model / parameters that will reasonably reproduce the well test results. After completing the first step, proceed with the well test data entry. 3.1.22.3.4.1 Well Test Data Entry
Well test data Parameter Test date (optional): Test Comment (optional): Well Head Flowing Pressure: Down hole Injection Temperature: Water Cut: Water Injection Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation: Gas-Oil Ratio [ Not Used]: GOR Free [ Not used]:
Value 01/01/2010 Main Flow Test 1250 psig 80 degF 100% 11000 stb/d 7500 ft 4350 psig top 3580 psig 0 scf/stb 0 scf/stb
In order to enter the well test data, simply select | Matching | Matching | VLP/IPR (Quality-Check) and populate the screen as below: The screen is divided into 3 sections: upper, middle and bottom. The upper section of the screen contains different buttons that can be categorized in two groups: the data processing button on the left and the task buttons The middle section contains the well test data and the bottom section of the screen contains in written form a well test matching procedure that has been successfully tested over and over again. This is the recommended well test matching procedure. When one intends to analyse a particular test, one needs to select this test point by clicking on the row number that starts at the beginning of each test entry, left of the column " Test Point Date". The selected test number then turns blue.
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Notes: - The approach to follow is documented at the bottom of the screen under"Matching Procedure". - This is an injection well with 100% water cut. Therefore, the parameters Gas Oil Ratio and GOR free are totally irrelevant. - We will primarily use the Task buttons located on the top right corner of the screen, from the left to the right to solve this well test matching exercise. 3.1.22.3.4.2 Estimate the U-value
In a design case, the U-value can be estimated using the full enthalpy balance model. Alternatively, when a well test is available, one can use the well test data to back calculate the overall heat transfer coefficient.This is what we are going to do next. For this simply select the task button "Estimate U Value" and the following message will appear:
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The program has estimated and displayed the heat transfer coefficient on the basis of the well test data selected. Under the assumption that the well test data are valid, select | OK and a message is displayed, proposing to replace the previous U-value in the model with this new one.
With YES, the new U-value is taken as input for the model. The previous value is in fact overwritten. Here we will select YES and then the U-value is then transferred:
Select | OK to continue with the next task button, the "Correlation Comparison". 3.1.22.3.4.3 Correlation Comparison
It is well known that there is no universal multiphase correlation. Therefore, whenever a new well test is available for analysis, it is a good practice to perform a correlation comparison. The purposes of the correlation comparison are: - identify without bias which best reproduce the well test to be analyse - quality check the well test results themselves. For instance if none of the correlation came close to the well test, it might be worth checking the reliability of the well test data themselves. © 1990-2011 Petroleum Experts Limited
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This is single phase system where all correlations are expected to yield the same results. Therefore, any major deviation between simulated pressure and measured pressure would be due either to the model inputs or the test data and possibly a combination of both: model inputs and well test data. To proceed, select the task button "Correlation Comparison" and then | OK | and here select a few correlations for comparison.
Now select | Calculate | Calculate | OK | Plot:
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As expected, all correlations give simular results. We will select the Petroleum Experts 2 correlation moving forward. Select | Main to return to the VLP/IPR Matching screen to fine-tune the Petroleum Experts 2 correlation against the well test data. The emphasis here is fine-tune because a heavy correction is not desired. 3.1.22.3.4.4 VLP matching
In order to fine-tune the VLP, simply select the task button "Match VLP" and the following screen appear:
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Select | All to select and then | All again to deselect all correlations. Now, having identified earlier the Petroleum Experts 2 correlation, we can can simply select the Petroleum Experts 2 correlation only and then click on | Match.
The parameter 1 is the gravity term multiplier whereas the parameter 2 is the friction term multiplier. Ideally, both should equal to unity and one can see here that both PROSPER Manual
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multipliers are very close indeed to unity. Now select | Done to return to the previous menu. 3.1.22.3.4.5 VLP / IPR matching
In order to perform the VLP/IPR matching, simply select the task button "VLP / IPR" and then | Calculate:
PROSPER computes VLP and IPR using the well test data as input. On the bottom right of the screen, the simulated solution rate and solution BHFP are displayed along with the test rate and test bottom hole flowing pressure. Note that "Test BHP" is the gauge pressure corrected to the well datum depth using the VLP correlation selected. With | Plot, this is what can be seen:
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One can read that the difference between measured and simulated rate is large. The question then arises: what is the source of this difference? Let us summarize: A well model is the combination of PVT, VLP and IPR. The water PVT has been entered, The VLP also have been sensibly calibrated. Hence any error will be confined to the IPR. There are multiple IPR variables that can help conclude the exercise: reservoir pressure, permeability, skin, and so on. In the following, we will assume that the skin has changed. Hence, we will adjust the skin to match the well test. This can be done manually in iterative fashion of automatically. For this select | Finish | IPR | Input Data | Mech / Geom Skin and raise the skin to 15!
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There may be a need to expand the validation range for skin values to 1000 for instance.
In any case, once the skin of 15.5 has been successfully entered, select | Done | Done | Done and | Calculate again to recompute the VLP and IPR. This is how the plot now looks like:
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The plot clearly shows that an acceptable match is achieved by multiplying the skin by a factor of more than 7. We have increased the skin from 2 to 15.5. A transient well test will be required to prove the uniqueness of this approach. Water injection physics When injecting cold water in a generally hotter reservoir, a few phenomena take place: - inside the reservoir, the temperature is lower in the vicinity of the injection point. - the lower temperature affects the water formation volume factor and the water viscosity and hence the water mobility. - the change in water mobility will impact the water injectivity. - the lower temperature will also affect the stress around the injection point and may lead to thermal fracturing. - the chemical composition of the injection water may not be compatible with the reservoir water. All this can lead to thermo-fracturing, scale deposition, viscous fingering, souring, and so on. These phenomena are best studied with REVEAL, the specialized reservoir simulator developed by Petroleum Experts. Select | Main and save the file to secure all changes made. 3.1.22.3.4.6 Performing Sensitivity runs
The table below contains the case to be evaluated:
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1750 psig 3000 psig 80 degF
In order to analyse the case described above, one will perform sensitivity run on the parameters listed above. For this, select | Calculation | System |3 Variable and make the following choice:
Note that the matched VLP correlation now appears with 2 numbers appended to it: 1.00 and 0.97 The first number (1.00) is the gravity multiplier whereas the second number (0.97) is the friction multiplier. Now select | Continue and select the remaining sensitivity variables of interest: reservoir pressure and tubing ID
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Please select | Continue and | Calculate | Ok and this is what will be seen:
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A water injection rate around 8700 stb per day is predicted. Now by selecting | Plot | System Plot, the system plot is displayed:
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Select | Main and save the file. This completes this tutorial.
3.1.23 Tutorial 22: Matching a gas injection well test File: ~/samples/PROSPER/T22_MatchingAGasInjectionWellTest.OUT The main objectives of this example are to show: · How to match a PROSPER gas injection well model to well test data · How to use the calibrated model to perform sensitivity runs on various variables
3.1.23.1Statement Of The Problem A PROSPER model for a gas injection well was built in tutorial 10. The injection well has been tested with surface pressure, injection rate and down hole pressure measurement. It is required to: PROSPER Manual
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- Recall the Tutorial_10.out PROSPER file - Analyse the well test results - Calibrate the PROSPER model to reproduce the well test results - Use the calibrated model to predict the injection rate when the reservoir pressure drops to 3000 psig and the well head pressure is 3500 psig and a reservoir temperature of 80 degF. 3.1.23.2PVT Lab data & Well Test data The basic available PVT data are: Parameter Gas gravity: Separator pressure: Condensate to Gas Ratio: Condensate Gravity: Water to Gas Ratio: Water salinity: Impurities (H2S, CO2 & N2): Injection gas temperature at the well head:
Value 0.6 (Air = 1) 250 psig 0 stb/MMscf 50 API 0 stb/MMscf 10000 ppm 0% 60 degF
Well test data Parameter Test date (optional): Test Comment (optional): Well Head Injection Pressure: Down hole Injection Temperature: Water To Gas Ratio: Condensate Gas Ratio: Gas Injection Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation:
Value 01/01/2010 Main Flow Test 2500 psig 93 degF 0 stb/MMscf 0 stb/MMscf 35.3 MMscf/d 7500 ft 2876 psig top 2800 psig
3.1.23.3Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - Recall the PROSPER model built in tutorial 10 - Review the PROSPER model - Quality-check and calibrate the PROSPER model against the injection well test data - Select the appropriate VLP correlation - Superimpose the IPR curve - Use the model to run sensitivity injection pressures. © 1990-2011 Petroleum Experts Limited
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3.1.23.3.1 Open the PROSPER file Select | File | Open, locate and open the file "Tutorial_10.OUT" in the sample directory.
3.1.23.3.2 Resetting any previous VLP matching This step is optional but might be required when an inherited PROSPER file contain matched multiphase correlations that need to be reset. In order to reset the VLP calibration parameters (Parameter 1 & Parameter 2), select | Matching | Correlation Parameters | Tubing. Afterwards, select | Reset All
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Select | Done to complete this step. 3.1.23.3.3 PVT matching For dry and wet gas, PVT matching is generally not required. The matching feature does exists though in PROSPER. The basic PVT data entered below are sufficient. Parameter Gas gravity: Separator pressure: Condensate to Gas Ratio: Condensate Gravity: Water to Gas Ratio: Water salinity: Impurities (H2S, CO2 & N2):
Value 0.6 (Air = 1) 250 psig 0 stb/MMscf 50 API 0 stb/MMscf 10000 ppm 0%
Now select | Done and save the file to secure all the changes made so far.
3.1.23.3.4 Matching - VLP /IPR Quality Check The general procedure in matching a well test can be broken in four (4) sequential steps: - First, critically review the well test results: are there in line with previous results? how reliable are the measurements? - Second, quality-check and calibrate the PVT. For water injection wells, it is not required to perform any PVT matching. - Third, quality-check, select, calibrate and validate the VLP correlation against the © 1990-2011 Petroleum Experts Limited
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actual tubing response - Fourth, find the IPR model / parameters that will reasonably reproduce the well test results. After completing the first step, proceed with the well test data entry. 3.1.23.3.4.1 Well Test Data Entry
Well test data Parameter Test date (optional): Test Comment (optional): Well Head Injection Pressure: Down hole Injection Temperature: Water To Gas Ratio: Condensate Gas Ratio: Gas Injection Rate: Measured Gauge depth: Measured Gauge pressure: Static Reservoir Pressure @ perforation:
Value 01/01/2010 Main Flow Test 2500 psig 93 degF 0 stb/MMscf 0 stb/MMscf 35.3 MMscf/d 7500 ft 2876 psig top 2800 psig
The screen is divided into 3 sections: upper, middle and bottom. The upper section of the screen contains different buttons that can be categorized in two groups: the data processing button on the left and the task buttons To analyse a particular test, one needs to select this test point by clicking on the row number that starts at the beginning of each test entry, left of the column " Test Point Date". The selected test number then turns blue. In order to enter the well test data, simply select | Matching | Matching | VLP/IPR (Quality-Check) and populate the screen as below:
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Note: The approach to follow is documented at the bottom of the screen under"Matching Procedure".
3.1.23.3.4.2 Estimate the U-value
In a design case, the U-value can be estimated using the full enthalpy balance model. Alternatively, when a well test is available, one can use the well test data to back calculate the overall heat transfer coefficient.This is what we are going to do next. For this simply select the task button "Estimate U Value" and the following message will appear:
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The program has estimated and displayed the heat transfer coefficient on the basis of the well test data selected. Under the assumption that the well test data are valid, select | OK and a message is displayed proposing to replace the previous U-value in the model with this new one. With YES, the new U-value is taken as input for the model. The previous value is in fact overwritten. Here we will select YES and then the U-value is then transferred:
Select | OK to continue with the next task button, the "Correlation Comparison". 3.1.23.3.4.3 Correlation Comparison
It is well known that there is no universal multiphase correlation. Therefore, whenever a new well test is available for analysis, it is a good practice to perform a correlation comparison. The purposes of the correlation comparison are: - identify without bias which best reproduce the well test to be analyse - quality check the well test results themselves. For instance if none of the correlation came close to the well test, it might be worth checking the reliability of the well test data themselves. This is single phase system where all correlations are expected to yield the same results. Therefore, any major deviation between simulated pressure and measured pressure would be due either to the model inputs or the test data and possibly a combination of both: model inputs and well test data. To proceed, select the task button "Correlation Comparison" and then | OK | and here select a few correlations for comparison.
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Now select | Calculate | Calculate | OK | Plot:
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All correlations expectedly give identical results. One can also see that they all match reasonably well the test point. We will select the Petroleum Experts 2 correlation moving forward. Select | Main to return to the VLP/IPR Matching screen to fine-tune the Petroleum Experts 2 correlation against the well test data. The emphasis here is fine-tune because a heavy correction is not desired. 3.1.23.3.4.4 VLP matching
In order to fine-tune the VLP, simply select the task button "Match VLP" and the following screen appear:
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Select | All to select and then | All again to deselect all correlations. Now, having identified earlier the Petroleum Experts 2 correlation, we can can simply select the Petroleum Experts 2 correlation only and then click on | Match.
The parameter 1 is the gravity term multiplier whereas the parameter 2 is the friction term multiplier. Ideally, both should equal to unity and one can see here that both multipliers are very close indeed to unity. Now select | Done to return to the previous menu. © 1990-2011 Petroleum Experts Limited
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3.1.23.3.4.5 VLP / IPR matching
In order to perform the VLP/IPR matching, simply select the task button "VLP / IPR" and then | Calculate:
PROSPER computes VLP and IPR using the well test data as input. On the bottom right of the screen, the simulated solution rate and solution BHFP are displayed along with the test rate and test bottom hole flowing pressure. Note that "Test BHP" is the gauge pressure corrected to the well datum depth using the VLP correlation selected. With | Plot, this is what can be seen:
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One can read that the difference between measured and simulated rate is less than 1% and can be considered acceptable. If the error was larger, then the question would have been: what would be at that stage the source of a large difference? Let us summarize: A well model is the combination of PVT, VLP and IPR. This is dry gas. Black oil correlations work fine for dry gase. The VLP correlations have been sensibly calibrated. Hence any error would be confined to the IPR. There are multiple IPR variables that could then help conclude the exercise: reservoir pressure, permeability, skin, and so on. The key lesson here is: the sequential approach in analyzing the PVT first, then the VLP and finally the IPR enables the user to confine possible inconsistencies in the model / data to a particular component: PVT, VLP or IPR. Select | Main and save the file to secure all changes made. 3.1.23.3.4.6 Performing Sensitivity runs
The table below contains the cases to be evaluated: Well head flowing pressure: Reservoir pressure:
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Reservoir temperature:
80 degF
In order to analyse the case described above, one will perform sensitivity run on the parameters listed above. For this, select | Calculation | System |3 Variable and make the following choice:
Note that the matched VLP correlation now appears with 2 numbers appended to i. Now select | Continue and select the remaining sensitivity variables of interest: reservoir pressure and temperature.
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Please select | Continue and | Calculate | Ok | Plot | System plot and the following plot shows:
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The well would inject around 92 MMscf/d. Select | Main to exit this screen. This completes this tutorial.
3.1.24 Tutorial 23: Continuous Gas Lift Design File: ~/samples/PROSPER/T23_ContinuousGasLiftDesign.OUT This example is based upon tutorial 20. For beginners, it is recommended to work through tutorial 20 before starting with this one. The main objectives of this example are to: · Modify the Tutorial_20.out PROSPER file created in tutorial 20. · Find the maximum production rate achievable using gas lift. · Determine the optimum lift gas injection rate and depth. · Design the operating and unloading valves. This example demonstrates how to: · Setup the gas lift design parameters. · Calculate the design production and gas injection rates. · Space out the valves. · Determine the valve trim sizes and dome pressures. PROSPER Manual
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· Calculate production sensitivities using the gaslift design. The design assumes that the reservoir pressure will drop to 3000 psig and that the water cut will rise to 80%. This example will guide the user through opening the existing Tutorial_20.out file, changing the calculation options and reservoir conditions, performing the design and finally saving the file under a new name. 3.1.24.1Statement of the Problem In tutorial 2, a PROSPER well model was built for a naturally flowing oil. In tutorial 3, the model was updated with PVT calibration. In tutorial 20, the well model was matched against actual well test data. This tutorial 23 is built on tutorial 20. The well has now been in production for some time. Reservoir pressure has declined, water cut has increased and well deliverability has reduced. To improve well productivity, the well will be converted to a gas lifted well. 3.1.24.2Input Data For Continuous GL design For a gas lift design, the following inputs are required: - PVT data, - IPR data, - Well equipment data - Gas lift design parameters 3.1.24.2.1 PVT Data In this tutorial, the file Tutorial_20 will be used that already contains a matched PVT. 3.1.24.2.2 Reservoir Data for GL design In this tutorial, the file Tutorial_20 will be used that already contains all the IPR description required. For the gas lift design tutorial, the following conditions apply. Reservoir Pressure: Water Cut:
3000 psig 80 %
All previous inputs remain unchanged. 3.1.24.2.3 Equipment Data In this tutorial, the file Tutorial_20 will be used that already contains all the equipment description required. 3.1.24.2.4 Gas Lift design parameters Gas lift gas PVT:
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Variable
Value
Gas lift gas gravity:
0.8
H2S mole percent:
0
CO2 mole percent:
0
N2 mole percent:
0
Gas lift design conditions: Design rate method: Maximum liquid rate: Maximum gas available: Maximum gas available during unloading: Flowing top node pressure: Unload top node pressure: Operating Injection pressure: Kick-off injection pressure: Desired dP across valve: Maximum Depth of Gas Lift Injection: Design water cut: Minimum valve spacing: Static gradient of kill fluid: Minimum transfer dP: Maximum Port size: Safety for closure of last unloading valve: Total GOR: De-rating Percentage for valves: Valve type: Minimum CHP decrease/valve: Valve setting: Injection point: Dome Pressure correction above 1200 psig: PROSPER Manual
Calculated from maximum production 30 000 stb/d 10 MMscf/d 10 MMscf/d 200 psig 200 psig 1500 psig 1500 psig 50 psig 7500 ft 80% 250 ft 0.46 psi/ft 25 % set by valves series selection 0 psi 400 100% Casing sensitive 50 psi All valves Pvo = Gas Pressure Injection point is an orifice Yes
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Check Rate conformance with Yes IPR: Vertical Lift Correlation: Petroleum Experts 2 Surface pipe correlation: Beggs and Brill Use IPR For Unloading: Yes Orifice sizing on: Calculated dP @ orifice De-Rating Percentage for 100% orifice: Valve series selection: Camco - R20 / Normal 3.1.24.3Step by step procedure The following step-by-step procedure will help to: - Recall an existing PROSPER file - Update the IPR input data - Describe the gas lift gas PVT - Design a continuous gas lift system - Use the model to perform sensitivity on gas lift gas injection rate. 3.1.24.3.1 Defining the options To start with, open the PROSPER sample file Tutorial_20.out. Afterwards, select | Options | Options and make the following changes: Artificial Lift Method: Gas Lift (Continuous) Artificial Lift Type: No Friction Loss In Annulus
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Select | Done to complete this. 3.1.24.3.2 Description of the gas lift PVT In order to describe the gas lift gas, select | System | Gas Lift Data and populate the screen as below: Variable
Value
Gas lift gas gravity:
0.8
H2S mole percent:
0
CO2 mole percent:
0
N2 mole percent:
0
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At this stage, the following changes can be made:
GLR injected:
0 scf/stb (default)
Gas lift Method:
Valve Depths Specified
Select | Done to complete this step. 3.1.24.3.3 Description of the IPR Only two changes are required here: the reservoir pressure and the water valid for the gas lift design. Reservoir Pressure: Water Cut:
3000 psig 80 %
All previous inputs remain unchanged.
Select | system | Inflow Performance and make the following changes:
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As a quick-check, select | Calculate to generate an IPR like this:
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Select | Main to get back to the main screen of PROSPER.
3.1.24.3.4 Description of the Gas Lift Design Conditions Here are the gas lift design parameters: Design rate method: Maximum liquid rate: Maximum gas available: Maximum gas available during unloading: Flowing top node pressure: Unload top node pressure: Operating Injection pressure: Kick-off injection pressure: Desired dP across valve: Maximum Depth of Gas Lift Injection: Design water cut: Minimum valve spacing:
Calculated from maximum production 30 000 stb/d 10 MMscf/d 10 MMscf/d 200 psig 200 psig 1500 psig 1500 psig 50 psig 7500 ft 80% 250 ft
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Static gradient of kill fluid:
0.46 psi/ft
Minimum transfer dP: Maximum Port size: Safety for closure of last unloading valve: Total GOR: De-rating Percentage for valves: Valve type: Minimum CHP decrease/valve: Valve setting: Injection point: Dome Pressure correction above 1200 psig: Check Rate conformance with IPR: Vertical Lift Correlation: Surface pipe correlation: Use IPR For Unloading: Orifice sizing on: De-Rating Percentage for orifice: Valve series selection:
25 % set by valves series selection 0 psi 400 100% Casing sensitive 50 psi All valves Pvo = Gas Pressure Injection point is an orifice Yes Yes Petroleum Experts 2 Beggs and Brill Yes Calculated dP @ orifice 100% Camco - R20 / Normal
To start the gas lift design, select | Design | Gas lift | New Well and populate the screen as shown below:
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In order to proceed, select | Continue | Get Rate and the following plot is generated with | OK | Plot:
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This performance curve is used by the gas lift design algorithm to define the oil rate the design will aim to produce. 3.1.24.3.5 Performing the gas lift design In order to perform the GL design, exit the well performance curve plot (Oil Rate versus Gas Injected) with | Finish and the select | Design:
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After a while, the design is completed and the results can be visualized with the | Plot tab in the lower half of the screen:
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P min represents the minimum pressure drop that could be achieved at a defined depth during unloading (when injecting at that defined depth). In other words, as gas lift is carried out and the pressure drop decreases, an optimal gas rate is achieved before too much is injected allowing the pressure drop to increase due to the friction. The ‘P min’ point represents the minimum pressure achieved at the defined valve depth as the optimal gas rate has been reached. P max represents the maximum pressure drop that could be achieved at a defined depth during unloading, it is the momentary maximum pressure value at the valve as it closes and the one below opens.
For more details about the design, select | Finish | Results | Calculate:
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Select | Main to exit this screen. 3.1.24.3.6 Transferring the valve depths Once a design is satisfactory, one needs to transfer the design results. For this, select | System | Gas Lift Data | Transfer | From Gas Lift Design | OK | Done and the valve depths are transferred across:
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For further calculations, it will be assumed that a fixed depth of injection applies. Therefore, the "Fixed Depth of Injection" gas lift method will be selected and the orifice depth entered as bellow:
Afterwards, select | Done and save the file to secure all changes. This completes the gas lift design. 3.1.24.3.7 System Calculation for a gas-lifted well Next, sensitivity calculations on gas lift injection rate will be performed with the well model created. For this, select | Calculations | System (Vlp + Ipr) | 3 Variables and make the following changes:
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First node Pressure: 250 psig Water Cut: 80% Total GOR: 400 scf/stb. Select | Continue | Reset All and then choose the variable gas lift gas injection rate. Populate the entry cells with the following values:
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Gas Lift Gas Injection Rate: 0, 0.5, 1, 1.5, 2, 2.5, 3, 5, 7 & 10 MMscf/d. With | Continue | Calculate | OK | Plot | System Plot, the following shows:
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It can be very useful to plot the oil rate versus the gas lift gas injection rate. For this, select | Finish | Sensitivity | Variables | Oil Rate Done:
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Select | Main to exit this screen. This completes this tutorial.
3.1.25 Tutorial 24: Intermittent Gas Lift design File: ~/samples/PROSPER/T24_IntermittentGasLiftDesign.OUT 3.1.25.1Introduction to intermittent Gas Lift Intermittent gas lift is a type of artificial lift that is used in low productivity well. Gas is injected on a cyclic basis to enable the liquid to build up in the well bore. The pictures below show the various stages of a cycle in intermittent gas lift from the instant the bottom valve opens: Liquid accumulates in the tubing. This is the slug. When the slug reaches a certain size, gas lift enters the tubing and lift the slug to the surface. The static liquid film against the inner diameter of the tubing falls back and the process is repeated.
PROSPER can be used to design intermittent gas lift systems. 3.1.25.2Statement of the problem Intermittent gas lift is to be designed for a low productivity well with the following parameter PVT Data Solution GOR: Oil Gravity: PROSPER Manual
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Gas Gravity:
0.6
Water Salinity: Gas impurities (CO2, N2, H2S): Bubble point pressure at 170 degF Oil FVF at 170 degF and 1650 psig: Oil Viscosity:
100000 ppm 0% 1650 psig 1.098 rb/stb 2.5 cp
1156
IPR data Reservoir model:
PI entry
Reservoir pressure:
1800 psig
Reservoir temperature:
170 degF
Water Cut:
80%
Total GOR:
200 scf/stb
Compaction permeability reduction model:
No
Relative permeability:
No
Productivity Index
1 stb/d/psi
Down hole equipment data Deviation survey
Measured depth in ft
True Vertical Depth in ft
0
0
7500
7500 Down hole equipment data
Equipment type
Measured Depth in ft
Inside Diameter inches
Outside in diameter inches
Roughness in in inches
Xmas
0
N/A
N/A
N/A
Tubing
7400
1.703
2.375
0.0006
Casing
7500
6.1
6.5
0.0006
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Geothermal gradient Measured depth in ft
Static Formation Temperature
0
0
7500
170
Overall Heat Transfer coefficient: 8 Btu/h/ft2/F Intermittent gas lift data Surface Injection Pressure:
1500 psig
Injection depth:
7000 ft
Gas lift gas gravity:
0.6 (Air = 1)
Well Head Flowing Pressure:
50 psig
Valve Port Size:
32/64 inches
Water Cut:
80%
Liquid level in the tubing:
4500 ft
3.1.25.3Step by step procedure The step by step procedure can be divided into two segments: - Setting up of the PROSPER model and - Performing the design of the gas lift system 3.1.25.3.1 Setting up the PROSPER model The procedure of setting up the PROSPER model is identical to the one described in tutorial 1. System options From the main Prosper screen, select | Options | Options and make the following changes: Artificial lift - Method:
Gas Lift (Intermittent)
Artificial lift - Type:
Gas lift
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Select | Done to complete this. PVT data Select | PVT | Input Data and enter the fluid stock tank properties as shown below:
Solution GOR:
200 scf/stb
Oil Gravity:
28 API
Gas Gravity:
0.6
Water Salinity:
100000 ppm
Gas impurities (CO2, N2, H2S):
0%
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In order to enter the match data, select | Match data and enter the fluid properties at down hole conditions as shown below: Bubble point pressure at 170 degF
1650 psig
Oil FVF at 170 degF and 1650 psig:
1.098 rb/stb
Oil Viscosity:
2.5 cp
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In order to match the PVT correlation to the down hole PVT data, select | Done | Regression | Match All | OK | Parameters:
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Ideally, Parameter 1, which is a multiplier, should be close to unity whereas the shift (Parameter 2) is expected to be around nil. Given the results of the regression, the Glaso correlation will be used for bubble point, solution GOR and oil FVF whereas the Beal et all correlation will be selected for the oil viscosity. Select | Done | Done and this is how the PVT data entry screen looks like:
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Note: a flashing message should indicate that the PVT have been matched. It should be ensured that the Glaso along with the Beal et al correlations have been selected on this screen. Select | Done to complete the fluid PVT data entry. Equipment Data Entry From the main PROSPER screen select | System | Equipment (Tubing etc) | All | Edit to start the equipment data entry with the deviation survey: Measured depth in ft
True Vertical Depth in ft
0
0
7500
7500
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Select | Done | Cancel to enter the down hole equipment described below: Down hole equipment data Equipment type PROSPER Manual
Measured Depth in ft
Inside Diameter
Outside in diameter
Roughness in in inches May, 2011
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inches
inches
Xmas
0
N/A
N/A
N/A
Tubing
7400
1.703
2.375
0.0006
Casing
7500
6.1
6.5
0.0006
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Select | Done to proceed with the entry of the geothermal gradient and the overall heat transfer coefficient:
Geothermal gradient Measured depth in ft
Static Formation Temperature
0
70
7500
170
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Select | Done | Done | Done to complete the description of the equipment. In order to describe the well inflow, select | system | Inflow Performance Relationship and make the following entries: IPR data Reservoir model: Reservoir pressure: Reservoir temperature: Water Cut:
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PI entry 1800 psig 170 degF 80%
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Total GOR:
200 scf/stb
Compaction permeability reduction model: Relative permeability: Productivity Index
No No 1 stb/d/psi
1166
To enter the well productivity index,select | Input Data in the the top right corner of the screen:
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Now select | Calculate and an IPR curve is generated as shown below:
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Select | Main to return to the PROSPER main screen. 3.1.25.3.2 Design of the intermittent gas lift In order to perform an intermittent gas lift design, select | Design | Intermittent Gas lift design and populate the input screen as shown: Intermittent gas lift data Surface Injection Pressure:
1500 psig
Injection depth:
7000 ft
Well Head Flowing Pressure:
50 psig
Valve Port Size:
32/64 inches
Water Cut:
80%
Liquid level in the tubing:
4500 ft
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For the design of the unloading valves, 2 options are currently available in PROSPER: - the constant surface closing pressure method and - the optiflow flow design procedure. To use either valve design option, simply select | Valves and make the relevant choice. 3.1.25.3.3 Constant Surface Closing Pressure design When a well is not producing, then fluid accumulates inside the well bore. For a gas lifted well, the tubing - annulus space through which gas lift is injected into the tubing can be filled with liquid that covers the the injection valve. Therefore, in order to kick-start the well, there is need to empty the annulus at least until the injection orifice / valve is uncovered. This is process of unloading requires the installation valves. One design method is the "constant surface closing pressure" design method. As the name suggests, the unloading valves are set in such a way that they all close at the PROSPER Manual
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same user-defined constant casing head pressure which is generally between 100 and 200 psi below the available surface injection pressure. In order to design the unloading valves, select | Design | Intermittent Gas Lift Design | Valves | Constant Surface Closing Pressure
Now enter the design parameters as done below: Surface injection pressure unloading): Unloading gradient: Spacing factor:
(during 1500 psig 0.45 psi/ft 0.2 psi/ft © 1990-2011 Petroleum Experts Limited
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Well head pressure:
50 psig
Surface closing pressure:
1300 psig (generally 100 - 200 psi lower than injection pressure 7000 ft
Maximum Injection depth:
The spacing factor corresponds to the minimum pressure gradient inside the tubing. It depends upon flow rate and tubing size and generally varies between 0.04 psi/ft and 0.2 psi/ft.
The valves depths are calculated and displayed along with the spacing pressure, the closing and the injection pressure.
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3.1.25.3.4 OptiFlow Gas Lift Valve Design method Another design method for the spacing of the unloading valves for an intermittent gas lift system is the optiflow method. According to the author (Handbook of Gas Lift by Axelson, US industries Inc., 1959 Intermittent Opti-Flow Section) the method is suitable for wells with little or no information about the well potential. In order to design the unloading valves with the optiflow method, select | Design | Intermittent Gas Lift Design | Valves | Optiflow Design Procedure. Now populate the design screen with the data provided: Surface injection pressure unloading):
(during 1500 psig
Unloading gradient:
0.45 psi/ft
Static BHFP:
1800 psig
Well head pressure:
50 psig
Maximum Injection depth:
7000 ft
Once the input data have been entered, select | Calculate and the static liquid level is © 1990-2011 Petroleum Experts Limited
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calculated. The method assumes a DP of 100 psi to open the valve. The valves spacing lines are computed for 30% and 90% of the surface opening pressure above the static liquid level. Below the static liquid level, the spacing lines are drawn for 55 and 85% of the surface opening pressure. With | Plot, the following graph is displayed:
Select | Done | Done | Done to complete th
3.1.26 Tutorial 25: Coiled Tubing Gas Lift Design File: ~/samples/PROSPER/T25_CoiledTubingGasLiftDesign.OUT This example builds upon tutorial 20. For beginners, it is recommended to work through tutorial 20 before starting with this one. The main objectives of this example are to: · Modify the Tutorial_20.out PROSPER file created in tutorial 20. · Find the maximum production rate achievable using gas lift. · Determine the optimum lift gas injection rate and depth. · Design the operating and unloading valves. PROSPER Manual
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This example demonstrates how to: · Setup the gas lift design parameters. · Calculate the design production and gas injection rates. · Space out the valves. · Determine the valve trim sizes and dome pressures. · Calculate production sensitivities using the gaslift design. The design assumes that the reservoir pressure will drop to 3000 psig and that the water cut will rise to 80%. This example will guide the user through opening the existing Tutorial_20.out file, changing the calculation options and reservoir conditions, performing the design and finally saving the file under a new name. 3.1.26.1Statement of the Problem In tutorial 2, a PROSPER well model was built for a naturally flowing oil. In tutorial 3, the model was updated with PVT calibration. In tutorial 20, the well model was matched against actual well test data. This tutorial 25 is built on tutorial 20. The well has now been in production for some time. Reservoir pressure has declined, water cut has increased and well deliverability has reduced. To improve well productivity, the well will be converted to a gas lifted well with coiled tubing. 3.1.26.2Input Data For Continuous GL design with Coiled Tubing For a gas lift design, the following inputs are required: - PVT data, - Reservoir data, - Well equipment data - Lift gas PVT and the coiled tubing Gas lift design parameters 3.1.26.2.1 PVT Data In this tutorial, the file from Tutorial 20 will be used that already contains a matched PVT model. 3.1.26.2.2 Reservoir Data for GL design In this tutorial, the file from Tutorial 20 will be used that already contains all the IPR description required. For the gas lift design tutorial, the following conditions apply. Reservoir Pressure: Water Cut:
3000 psig 80 %
All previous inputs remain unchanged.
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3.1.26.2.3 Equipment Data In this tutorial, the file from Tutorial 20 will be used that already contains all the equipment description required. 3.1.26.2.4 Coiled Tubing Gas Lift design parameters Gas lift gas PVT: Variable
Value
Gas lift gas gravity:
0.8
H2S mole percent:
0
CO2 mole percent:
0
N2 mole percent:
0
Gas lift design conditions: Maximum gas available: 10 MMscf/d Maximum gas available during 10 MMscf/d unloading: Flowing top node pressure: 200 psig Unload top node pressure: Operating Injection pressure: Kick-off injection pressure: Desired dP across valve: Maximum Depth of Gas Lift Injection: Design water cut: Static gradient of kill fluid: Total GOR: Design Rate Method: Maximum Liquid Rate: Check Rate conformance with IPR: Use IPR For Unloading: Orifice sizing on: Vertical Lift Correlation: Surface pipe correlation:
PROSPER Manual
200 psig 2000 psig 2000 psig 50 psig 7500 ft 80% 0.46 psi/ft 400 scf/stb Calculated From Max Production 30000 stb/d Yes Yes Calculated dP @ orifice Petroleum Experts 2 Beggs and Brill
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3.1.26.3Step by step procedure The following step-by-step procedure will help to: - Recall an existing PROSPER file - Update the IPR input data - Describe the gas lift gas PVT - Design a continuous gas lift system - Use the model to perform sensitivity on gas lift gas injection rate. 3.1.26.3.1 Defining the options To start with, open the PROSPER sample file Tutorial_20.out. Afterwards, select | Options | Options and make the following changes: Artificial Lift Method: Coiled Tubing Gas Lift Artificial Lift Type: No Friction Loss In Annulus
Select | Done to complete this. © 1990-2011 Petroleum Experts Limited
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3.1.26.3.2 Gas lift PVT and CT Data In order to describe the gas lift gas, select | System | Coiled Tubing Data and populate the screen as below: Gas lift PVT Variable
Value
Gas lift gas gravity:
0.8
H2S mole percent:
0
CO2 mole percent:
0
N2 mole percent:
0
Coiled Tubing Data Variable
Value
Coiled Tubing Inside Diameter: 0.8 inches Coiled tubing thickness:
0.2 inches
Coiled tubing inside roughness: 0.0006 inches Coiled Tubing Roughness:
Outside 0.0006 inches
Note that in the event a coiled tubing gas lift has already been designed, then one will PROSPER Manual
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simply populate this screen and then proceed with the system calculations. Select | Done to complete this step. 3.1.26.3.3 Description of the IPR Only two changes are required here: the reservoir pressure and the water valid for the gas lift design. Reservoir Pressure: Water Cut:
3000 psig 80 %
All previous inputs remain unchanged. Select | system | Inflow Performance and make the following changes:
As a quick-check, select | Calculate to generate an IPR like this:
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Select | Main to get back to the main screen of PROSPER. 3.1.26.3.4 Description of the CT Gas Lift Design Conditions Here are the CT gas lift design parameters:
Maximum gas available: Maximum gas available during unloading: Flowing top node pressure: Unload top node pressure: Operating Injection pressure: Kick-off injection pressure: Desired dP across valve: Maximum Depth of Gas Lift Injection: Design water cut: Static gradient of kill fluid: Total GOR: Design Rate Method: PROSPER Manual
10 MMscf/d 10 MMscf/d 200 psig 200 psig 2000 psig 2000 psig 50 psig 7500 ft 80% 0.46 psi/ft 400 scf/stb Calculated From Max Production May, 2011
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Maximum Liquid Rate:
1180
30000 stb/d
Check Rate conformance with Yes IPR: Use IPR For Unloading: Yes Orifice sizing on: Calculated dP @ orifice Vertical Lift Correlation: Petroleum Experts 2 Surface pipe correlation: Beggs and Brill To start the coiled tubing (CT) gas lift design, select | Design | Coiled Tubing Gas lift and populate the screen as shown below:
In order to proceed, select | Continue | Get Rate |OK | Plot:
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This performance curve is used by the gas lift design algorithm to define the oil rate the design will aim to produce. 3.1.26.3.5 Performing the CT gas lift design In order to perform the coiled tubing (CT) Gas Lift design, exit the well performance curve plot (Oil Rate versus Gas Injected) with | Finish and the select | Design: After a while, the design is completed and the results can be visualized with the | Plot tab in the lower half of the screen:
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Note that the bottom section of the screen displays the results of the design. The results can be transferred to the
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Select | Main to exit this screen.
3.1.26.3.6 Fixing the CT injection depth Once a design is satisfactory, one needs to transfer the design results. For this, select | System | Coiled Tubing Gas Lift Data and populate the screen as follow:
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Afterwards, select | Done and save the file to secure all changes. This completes the gas lift design. 3.1.26.3.7 System Calculation for a CT gas-lifted well Next, sensitivity calculations on gas lift injection rate will be performed with the well model created. For this, select | Calculations | System (Vlp + Ipr) | 3 Variables and make the following changes:
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First node Pressure: 250 psig Water Cut: 80% Total GOR: 400 scf/stb. Select | Continue | Reset All and then choose the variable gas lift gas injection rate. Populate the entry cells with the following values:
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Gas Lift Gas Injection Rate: 0, 0.5, 1, 1.5, 2, 2.5, 3, 5, 7 & 10 MMscf/d. With | Continue | Calculate | OK | Plot | System Plot, the following shows:
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It can be very useful to plot the oil rate versus the gas lift gas injection rate. For this, select | Finish | Sensitivity | Variables | Oil Rate Done:
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Select | Main to exit this screen. This completes this tutorial.
3.1.27 Tutorial 26: ESP Design File: ~/samples/PROSPER/T26_ESPDesign.OUT This example is based upon tutorial 20. For beginners, it is recommended to work through tutorial 20 before starting with this one. The main objectives of this example are to: · Modify the the PROSPER file created in tutorial 20. · Find the the ESP system required to produce a given flow rate. This example demonstrates how to: · Design an ESP system · Calculate sensitivities on pump frequency. The design assumes that the reservoir pressure will drop to 3000 psig and that the water cut have risen to 80%. This example will guide the user through opening the existing PROSPER file from tutorial 20, which name starts with T20_xxx.OUT and changing the calculation options and reservoir conditions, performing the design and finally saving the file under a new name. 3.1.27.1Statement of the Problem In tutorial 2, a PROSPER well model was built for a naturally flowing oil. In tutorial 3, the model was updated with PVT calibration. In tutorial 20, the well model was matched against actual well test data. This tutorial 23 is built on tutorial 20. The well has now been in production for some time. Reservoir pressure has declined, water cut has increased and well deliverability has reduced. To improve well productivity, the well will be converted to an ESP-lifted well. 3.1.27.2Input Data For ESP design For a ESP design, the following inputs are required: - PVT data, - IPR data, - Well equipment data - ESP design parameters 3.1.27.2.1 PVT Data In this tutorial, the file Tutorial_20 will be used that already contains a matched PVT.
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3.1.27.2.2 Reservoir Data for ESP design In this tutorial, the file Tutorial_20 will be used that already contains all the IPR description required. For the gas lift design tutorial, the following conditions apply. Reservoir Pressure: Water Cut:
3000 psig 80 %
All previous inputs remain unchanged. 3.1.27.2.3 Equipment Data In this tutorial, the file Tutorial_20 will be used that already contains all the equipment description required. Since the ESP has to fit inside of the casing, additional details are required for the down hole equipment description. These details are: Tubing Outer Diameter: 4.5 inches throughout. Casing Internal Diameter: 8.3 inches throughout 3.1.27.2.4 ESP design parameters ESP design conditions: Pump Depth (Measured):
7000 ft
Operating Frequency:
60 Hertz
Maximum Diameter:
Pump
Outer 6 inches
Length of cable:
7000 ft
Gas separator efficiency:
0%
Design liquid rate:
12 000 stb/d
Water Cut:
80%
Total GOR:
400 scf/stb
Top Node Pressure:
250 psig
Motor Power Safety Margin:
0%
Pump Wear Factor:
0%
Surface pipe correlation:
Beggs and Brill
Vertical Lift Correlation:
Petroleum Experts 2
Gas de-Rating model:
None
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3.1.27.3Step by step procedure The following step-by-step procedure will help to: - Recall an existing PROSPER file - Update the IPR input data - Complete the down hole description - Design an ESP lift system - Use the model to perform sensitivity on pump frequency. 3.1.27.3.1 Defining the options To start with, open the PROSPER sample file Tutorial_20.out. Afterwards, select | Options | Options and make the following changes: Artificial Lift Method: Electrical Submersible Pump
Select | Done to complete this. © 1990-2011 Petroleum Experts Limited
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3.1.27.3.2 Description of the well down hole equipment In this tutorial, the file Tutorial_20 will be used that already contains all the equipment description required. Since the ESP has to fit inside of the casing, additional details are required for the down hole equipment description. These details are: Tubing Outer Diameter: 4.5 inches throughout. Casing Internal Diameter: 8.3 inches throughout Roughness: 0.0018 inches throughout Select | System | Equipment (Tubing etc) | Downhole to complete the down hole description as shown below:
Select | Main to complete this step. 3.1.27.3.3 Description of the IPR Only two changes are required here: the reservoir pressure and the water valid for the gas lift design. PROSPER Manual
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Reservoir Pressure: Water Cut:
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3000 psig 80 %
All previous inputs remain unchanged. Select | system | Inflow Performance and make the following changes:
As a quick-check, select | Calculate to generate an IPR like this:
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Select | Main to get back to the main screen of PROSPER. 3.1.27.3.4 Description of the ESP Design Conditions Here are the ESP lift design parameters:
Pump Depth (Measured): Operating Frequency: Maximum Pump Outer Diameter: Length of cable: Gas separator efficiency: Design liquid rate: Water Cut: Total GOR: Top Node Pressure: Motor Power Safety Margin: Pump Wear Factor: Surface pipe correlation:
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7000 ft 60 Hertz 6 inches 7000 ft 0% 12 000 stb/d 80% 400 scf/stb 250 psig 0% 0% Beggs and Brill
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Vertical Lift Correlation:
Petroleum Experts 2
Gas de-Rating model:
None
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To start the ESP design, select | Design | Electrical Submersible Pump and populate the screen as shown below:
At design stage, it is recommended to start with not gas separation, assess the need for gas separation using the the Dunbar Plot before making a decision. 3.1.27.3.5 Performing the ESP design In order to perform the ESP design, select | Calculate | Calculate | OK:
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The screen above summarizes all the parameters required to choose a pump system. In order to assess the need for down hole gas separation, select | Sensitivity to visualize the Dunbar plot:
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The Dunbar plot is an empirical relation that can be interpreted as follow: if the test point is above the red curve, then down holw gas separation is not required. Otherwise, down hole gas separation is recommended. In this example, down hole separation is not needed. Select | Finish | Done to return to the ESP design screen. Now select | Design and select the Pump, the motor and the cable as below:
In order to see the pump performance curve, select | Plot
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Select | Main to exit this screen. 3.1.27.3.6 System Calculation for an ESP-lifted well Next, sensitivity calculations on pump frequency will be performed with the well model created. For this, select | Calculations | System (Vlp + Ipr) | 3 Variables and make the following changes:
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First node Pressure: 250 psig Water Cut: 80% Total GOR: 400 scf/stb. Select | Continue | Reset All and then choose the variable operating frequency. Populate the entry cells with the following values:
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Operating frequencies: 45, 50, 55, 60, 65, 70 Hz. With | Continue | Calculate | OK | Plot | System Plot, the following shows:
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The following aspects need to be considered when interpreting the VLP/ IPR plot for an ESP-lifted well. · At the reference depth, the IPR is computed · At the pump depth, the Pump Intake Pressure is computed · At the discharge of the pump, PROSPER compute the pump discharge pressure at the pump depth · The VLP is computed between the top node pressure and the discharge of the pump · Therefore, the solution rate is the intersection between pump discharge pressure and VLP NOTE: The solution of an ESP well is the intersection of the VLP and pump discharge pressure curve ONLY when the Rough Approximation thermal calculation option is used. Ü
When the Improved Approximation or Enthalpy Balance thermal calculation options (not available for ESP design) are used for a system calculation for instance, the solution of the well is the intersection of the VLP and IPR. The change in convention is due to PROSPER iterating through the complete well completion (including the ESP) to obtain a thermal balance based on the defined boundary conditions. The pump intake and discharge pressure curves become meaningless when using the advance thermal calculation options.
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· All plots can be visualized | Variables. Now select the pertinent curves as done below:
Select | Done and the following plot shows:
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It can be very useful to plot the oil rate versus the pump operating frequency. For this, select | Finish | Sensitivity | Variables | Oil Rate Done:
Finally, it is always recommended to compare the pump operating conditions with the pump performance curve. © 1990-2011 Petroleum Experts Limited
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For this, select | Finish | Solution Details | Pump Plot and this is what shows:
This example shows the pump operates inside the recommended envelope for all conditions considered. Select | Main to exit this screen. This completes this tutorial. 3.1.27.3.7 Notes on system plot (VLP+IPR) for ESP-lifted wells When an ESP is present in the well, the nodal analysis is carried out at the bottom of the well rather than the bottom hole: Naturally flowing production well: For a naturally flowing well, the solution node is placed at the bottom hole which results in the VLP accounting for the pressure drop from the wellhead to the bottomhole.
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ESP lifted production well: In the case of an ESP-lifted well, the solution node is placed at the top of the ESP. This means that the VLP accounts for the pressure drop from the wellhead to the top of the ESP. The IPR includes the pressure drop across the reservoir. The pump intake pressure (PIP) includes the pressure drop across the reservoir plus the pressure drop in the well up to the pump inlet. This is effectively the well inflow corrected to the inlet of the pump. The pump discharge pressure (PDP) includes the pressure drop across the reservoir plus the pressure drop in the well up to the pump inlet and the pressure gain across the © 1990-2011 Petroleum Experts Limited
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ESP.This is effectively the well inflow corrected to the discharge of the pump. Ultimately, the solution rate is the intersection between the VLP and the PDP.
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The resulting IPR is the obtained in the following way:
These plots then combine as seen by the light blue dashed line to give the resulting IPR within which the ESP effects are felt. To access the same plot within PROSPER, after running the system calculation, select: PLOT | SYSTEM PLOT | VARIABLES, the pump intake and discharge pressure can then be selected and displayed as shown below:
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3.1.28 Tutorial 27: Design of an Hydraulic Downhole Pump for an oil well File: ~/samples/PROSPER/T27_HSPDesign.OUT The objectives of this example are to: ·
Select a suitable combination of pump and turbine.
This example demonstrates how to: · · · ·
Use existing PVT and VLP data as the basis of a new analysis Calculate pump intake and outlet pressures Design an HSP system Evaluate pump operating point sensitivities
3.1.28.1Statement of the Problem In tutorial 2, a PROSPER well model was built for a naturally flowing oil. In tutorial 3, the model was updated with PVT calibration. In tutorial 20, the well model was matched against actual well test data. This tutorial 26 is built on tutorial 20. The well has now been in production for some time. Reservoir pressure has declined, water cut has increased and well deliverability has reduced. To improve well productivity, the well will be converted to an HSP-lifted well. The hydraulic submersible pump (HSP) is a type of pump to consider for highly viscous fluids or high GOR at pump suction conditions. The program will be used to select an HSP and turbine from the artificial lift database PROSPER Manual
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that fits the design criteria. 3.1.28.2Input Data For HSP design For a gas lift design, the following inputs are required: - Produced Fluid PVT data and Power fluid PVT data - IPR data, - Well equipment data - HSP design parameters 3.1.28.2.1 Produced Fluid & Power Fluid PVT Data In this tutorial, the file Tutorial_20 will be used that already contains a matched PVT. For the power fluid, the following inputs apply: HSP Power Fluid Properties: Power Fluid: Power Fluid Salinity:
Water 10 000 ppm
3.1.28.2.2 Reservoir Data for HSP design In this tutorial, the file Tutorial_20 will be used that already contains all the IPR description required. For the HSP design tutorial, the following IPR conditions apply. Reservoir Pressure: Water Cut:
3000 psig 80 %
All previous inputs remain unchanged. 3.1.28.2.3 Equipment Data In this tutorial, the file Tutorial_20 will be used that already contains all the equipment description required. Since the HSP has to fit inside of the casing, additional details are required for the down hole equipment description. These details are: Tubing Outer Diameter: 4.5 inches throughout. Casing Internal Diameter: 8.3 inches throughout 3.1.28.2.4 HSP design parameters HSP design conditions: Pump Depth (Measured): Pump maximal Allowable OD:
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Turbine maximal Allowable OD: 8 inches Design liquid rate: Design liquid rate: Top Node Pressure: Pump speed: Total GOR: Percent Power Fluid Reservoir Fluid: Pump Wear Factor: Surface pipe correlation: Vertical Lift Correlation: Gas de-Rating model:
7000 ft 15 000 stb/d 250 psig 6000 rpm 400 scf/stb Of 50 % 0% Beggs and Brill Petroleum Experts 2 None
3.1.28.3Step by step procedure The following step-by-step procedure will help to: - Recall an existing PROSPER file - Update the IPR input data - Complete the down hole description - Design an ESP lift system - Use the model to perform sensitivity on pump frequency. 3.1.28.3.1 Defining the options To start with, open the PROSPER sample file Tutorial_20.out. Afterwards, select | Options | Options and make the following changes: Artificial Lift Method: Hydraulic Drive Downhole Pump Artificial Lift Type: Commingled Annular Supply
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Select | Done to complete this. 3.1.28.3.2 Produced Fluid & Power Fluid PVT Data In this tutorial, the file Tutorial_20 will be used that already contains a matched PVT. For the power fluid, the following inputs apply: HSP Power Fluid Properties: Power Fluid:
Water
Power Fluid Salinity:
10 000 ppm
Select | PVT | Input Data and make the following entries for the power fluid:
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Select | Done to complete this step. 3.1.28.3.3 Description of the well down hole equipment In this tutorial, the file Tutorial_20 will be used that already contains all the equipment description required. Since the pump has to fit inside of the casing, additional details are required for the down hole equipment description. These details are: Tubing Outer Diameter: 4.5 inches throughout. Casing Internal Diameter: 8.3 inches throughout Roughness: 0.0018 inches throughout Select | System | Equipment (Tubing etc) | Downhole to complete the down hole description as shown below:
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Select | Main to complete this step. 3.1.28.3.4 Description of the IPR Only two changes are required here: the reservoir pressure and the water valid for the gas lift design. Reservoir Pressure: Water Cut:
3000 psig 80 %
All previous inputs remain unchanged. Select | system | Inflow Performance and make the following changes:
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As a quick-check, select | Calculate to generate an IPR like this:
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Select | Main to get back to the main screen of PROSPER. 3.1.28.3.5 HSP Design Here are the HSP lift design parameters: Pump Depth (Measured): Pump maximal Allowable OD: Turbine maximal Allowable OD: Design liquid rate: Water Cut of Produced Fluid: Top Node Pressure: Pump speed: Total GOR: Percent Power Fluid Of Reservoir Fluid: Pump Wear Factor: Surface pipe correlation: Vertical Lift Correlation: Gas de-Rating model:
7500 ft 8 inches 8 inches 15 000 stb/d 80% 250 psig 6000 rpm 400 scf/stb 50 % 0% Beggs and Brill Petroleum Experts 2 None © 1990-2011 Petroleum Experts Limited
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To enter the design parameters, select | Design | Hydraulic Pump and populate the entry cells as below:
Select | Calculate | Calculate to compute the operating conditions of the pump:
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Now select | Done | Design and here select first the pump and then the turbine:
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One can display the pump plot with | Pump Plot.
select | Finish to return to the previous screen. Equally, one can display the turbine plot with | Turbine Plot:
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Select | Done. From the design screen, one can perform directly a system calculation (Vlp + Ipr) to verify the actual pump performance. For this select | System | Continue | Reset All | Continue | Calculate:
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Select | Main to exit this screen. This completes this tutorial.
3.1.29 Tutorial 28: Sucker Rod Pump Design File: ~/samples/PROSPER/T28_SuckerRodPumpDesign.OUT The objectives of this example are to:
PROSPER Manual
·
Create a new PROSPER file.
·
Set the artificial lift options to Sucker Rod Pump.
·
Enter the relevant PVT, downhole equipment and IPR data.
·
Complete the SRP design and select a suitable pump and rod string combination.
·
Evaluate the pump performance using the system calculation sensitivities.
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3.1.29.1Statement of the Problem Given PVT data, Reservoir data, SRP design parameters and well completion data, it is required to: - Design a sucker rod pump (SRP) for a low rate oil well with a target liquid rate of 200 stb/d. - Predict the well performance under changing operating conditions 3.1.29.2Input Data for SRP-Design For a SRP- design, the following data sets are needed: - PVT data, - Well equipment data - Reservoir data - SRP- design parameters 3.1.29.2.1 Fluid Properties Solution GOR:
160 scf/stb
Oil Gravity:
25 API
Specific gas gravity:
0.68 (Air =1)
Water salinity:
80000 ppm
Pb at 130 degF:
1300 psig
Bo @ Pb and 130 degF:
1.06 rb/sb
µ 0 @ Pb and 130 degF:
8.87 cp
3.1.29.2.2 Equipment Data 3.1.29.2.2.1 Deviation Survey
Measured Depth in ft
True Vertical Depth in ft
0
0
3500
3500
3.1.29.2.2.2 Surface Equipment
The surface pipes are not included in this tutorial. 3.1.29.2.2.3 Downhole Equipment
Equipme Measure Tubing Tubing nt Type d Depth ID Inside
Tubin Tubing g OD Inside
Casin Casing g ID Inside
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Roughne ss
Roughnes s
Roughnes s
ft
inches
inches
inches inches
inches inches
Xmas
0
N/A
N/A
N/A
N/A
N/A
Tubing
3500
2.441
0.0012
2.625 0.0012
6.3
0.0012
N/A
3.1.29.2.2.4 Geothermal Gradient
Measured Depth in ft
Static Ambient Temperature
0
60
3500
130
Overall Heat Transfer Coefficient: 8 Btu/h/ft2/F 3.1.29.2.2.5 Average Heat Capacities
The default average heat capacity values will be used for this tutorial. 3.1.29.2.3 Inflow Performance Relation Inflow Performance Data Reservoir model:
PI Entry
Reservoir pressure:
1500 psig
Reservoir Temperature:
130 degF
Water Cut:
80 %
Total GOR:
160 scf/stb
Compaction Permeability model:
NO
Relative Permeability:
NO
Productivity Index:
0.25 stb/d/psi
3.1.29.2.4 SRP-Design parameters Anchored Tubing:
Yes
Pump depth:
3500 ft
Pump Diameter:
1.75 inches
Surface stroke length:
48 inches
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Pump Speed:
12 strokes / minutes
Rode Selection - Rod type:
Steel Rods
Rod Number:
ROD99/04
Gas Anchor Method:
Entered
Gas Anchor Efficiency:
0.8 (fraction)
Type:
Poor Boy
Annulus Area:
1.5 in2
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Further deign parameters are: Calculation mode:
Enter Production Rate, Estimate Stroke Rate
Pumping Unit Selection:
LUFKIN C-320-305-100 LC044
Rod Grad:
D
Service Factor:
Non-corrosive
Pump Intake Pressure Method:
Entered
Mid Perforation Depth:
3500 ft
Design Input - Unit type:
Conventional Clockwise
Design Input - Anchored tubing:
Yes
Design Input - MidPoint Perforation 3500 ft depth: Design Input - Pump Depth: Design Input Efficiency:
-
Pump
3500 ft Volumetric 80%
Design Input - Unit Efficiency:
75%
Design Input - Pump Diameter:
1.75-in
Design Input - Surface Stroke length:
48 "
Design Input - Bottom Hole Temperature: 130 degF Design Input - Well Head Temperature:
90 degF
Design Input - Well Head Pressure:
100 psig
3.1.29.3Step by step SRP design The step-by-step will take the reader through all necessary stages required to: - Build a PROSPER well model, - Design a Sucker Rod Pump for the well © 1990-2011 Petroleum Experts Limited
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- Use the well model to predict the well performance under changing operating conditions. 3.1.29.3.1 Options Select | File | New to open a new PROSPER file. Afterwards, select | Options | Options and make the following changes: Artificial Lift Method: Sucker Rod Pump
Select | Done to complete this task. 3.1.29.3.2 PVT Data: Input & Matching Select | PVT | Input Data and populate the screen as below: Solution GOR: PROSPER Manual
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Oil Gravity:
25 API
Specific gas gravity:
0.68 (Air =1)
Water salinity:
80000 ppm
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In order to enter the fluid properties at non-standard conditions, select | Match Data and populate the screen as follow:
Solution GOR:
160 scf/stb
Pb at 130 degF:
1300 psig
Bo @ Pb and 130 degF:
1.06 rb/sb
µ 0 @ Pb and 130 degF:
8.87 cp
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Select | Done | Regression | Match All | OK | Parameters to inspect the statistics of the non-linear regression:
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Parameter 1 is a multiplier and is ideally equal to unity. Parameter 2 is a shift and is ideally equal to nil. On the basis of the regression results, the Glaso correlation and Beal et al black oil correlation will be selected for this tutorial. Select | Done | Done and ensure that Glaso and Beal et have been effectively selected as black oil correlations:
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Select | Done to complete this step. 3.1.29.3.3 System Equipment Select | System | Equipment (Tubing etc) | All | Edit to enter the deviation survey Measured Depth in ft
True Vertical Depth in ft
0
0
3500
3500
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Select | Done to proceed to the surface equipment screen:
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On the surface equipment equipment screen, make sure that the the recommended ELF choke model is selected. For validation only, enter: Temperature of Surroundings: 60 degF Overall Heat Transfer Coefficicnet: 8 Btu/h/ft2/F. Select | Done to proceed to the Downhole Equipment description screen:
Equipme Measure Tubing Tubing nt Type d Depth ID Inside Roughne ss
Tubin Tubing Casin Casing g OD Inside g ID Inside Roughnes Roughnes s s
ft
inches
inches
inches inches
inches inches
Xmas
0
N/A
N/A
N/A
N/A
N/A
Tubing
3500
2.441
0.0012
2.625 0.0012
6.3
0.0012
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Select | Done to continue to the Geothermal Gradient input screen: Measured Depth in ft
Static Ambient Temperature
0
60
3500
130
Overall Heat Transfer Coefficient: 8 Btu/h/ft2/F
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Select | Done and accept the default average heat capacities with | Default | Done. Now select | Done to complete this step.
3.1.29.3.4 SRP Data Select | Sucker Rod Pumps and make the following choices to start with:
Anchored Tubing:
Yes
Pump depth:
3500 ft
Pump Diameter:
1.75 inches
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Surface stroke length:
48 inches
Pump Speed:
12 strokes / minutes
Rode Selection - Rod type:
Steel Rods
Rod Number:
ROD99/04
Gas Anchor Method:
Entered
Gas Anchor Efficiency:
0.8 (fraction)
Type:
Cup Type
Annulus Area:
1.5 in2
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Each input made here can be altered later during the design process if judged necessary. Note: A gas anchor is a bottom hole gas separator. Select | Done to complete this step.
3.1.29.3.5 Inflow Performance Data Select | System | Inflow Performance and populate the screen as follow: Reservoir model:
PI Entry
Reservoir pressure:
1500 psig
Reservoir Temperature:
130 degF
Water Cut:
80 %
Total GOR:
160 scf/stb
Compaction Permeability model:
NO
Relative Permeability:
NO
Productivity Index:
0.25 stb/d/psi
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Select | Input Data and enter the productivity index of 0.25 stb/d/psi:
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Select | Calculate afterwards to generate an IPR:
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Select | Finish to return to the previous screen. Since the target rate is 200 stb/d, one can estimate the bottom hole flowing pressure required for this target rate with | Sensitivity | Rate Method "User Selected" and enter 200 stb/d as rate.
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Now select | Continue | Continue | Calculate and the IPR pressure required to produce 200 stb/d is calculated and displayed. It is 651.5 psig.
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Select | Main to complete this step. 3.1.29.3.6 SRP Design Select | Design | Sucker Rod Pump and enter the following design parameters: Calculation mode:
Enter Production Rate, Estimate Stroke Rate
Target Production Rate:
200 stb/d
Pumping Unit Selection:
LUFKIN C-320-305-100 LC044
Rod Grad:
D
Service Factor:
Non-corrosive
Pump Intake Pressure Method:
Entered - 651.5 psig
Mid Perforation Depth:
3500 ft
Design Input - Unit type:
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Design Input - Anchored tubing:
Yes
Design Input - MidPoint Perforation 3500 ft depth: Design Input - Pump Depth: Design Input Efficiency:
-
Pump
3500 ft Volumetric 80%
Design Input - Unit Efficiency:
75%
Design Input - Pump Diameter:
1.75-in
Design Input - Surface Stroke length:
48-in
Design Input - Bottom Hole Temperature: 130 degF Design Input - Well Head Temperature:
90 degF
Design Input - Well Head Pressure:
100 psig
Select | Design | Sucker Rod Pump and enter the design data:
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One the data have been properly entered, select | Calculate to complete the design. It is possible to run sensitivity on the rod with | Rod Sensitivity | Calculate and the following screen shows:
Select | Done | Done to complete the SRP design. © 1990-2011 Petroleum Experts Limited
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3.1.29.4Running sensitivities with a SRP-lifted well model In order to run sensitivity on the pump speed, select | Calculation | System (Ipr + Vlp) | 3 Variables and make the following entries: Top Node Pressure:
100 psig
Water Cut:
80%
Total GOR:
160 scf/stb
Select | Continue and then select the variable "Pumping speed" with the following values: 12, 14, 16, 18 & 20 strokes/minute
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Proceed with | Continue | Calculate | OK | Plot:
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One can see how the predicted flow rate increases with the pumping speed. This completes this tutorial. Select | Main to exit the screen.
3.1.30 Tutorial 29: Progressive Cavity Pump (PCP) Design File: ~/samples/T29_PCPDesign.OUT In this example we will perform a design of a PCP (Progressive cavity pump) in an oil well. The objectives of this example are: · In this example it will be demonstrated how to enter PCP pump data in the database section · To perform a Design of a PCP to increase the oil production. · To perform a Calculation System using a PCP lift system. 3.1.30.1Statement of the Problem It is intended to design a PCP for an oil well. Fluid data (PVT), reservoir data (IPR) and well equipment data (VLP) are available. Pump and sucker rod data were obtained from the PCP vendor as well. It is required to: - Add the particular PCP pump into the PROSPER database PROSPER Manual
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- Add the sucker rod into the PROSPER database - Build a PROSPER model for the oil well - Design a PCP for the well - Use the PCP-lifted well model for sensitivity calculations.
3.1.30.2Adding a PCP to the pump database The following pump characteristics were obtained from the pump supplier:
Manufacturer : Pump Series : Pump Model : Pump Size : Maximum Head : Reference Speed : Reference Rate : Pump Volume :
Tutorial29 4" 400TP1350 4.72 inches 4430 ft 500 rpm 2534 stb/d 34 in3
Pump Length : Stator Pitch : Specific Rotor OD : Rotor Elements :
28.5433 ft 15.2756 inches 1.49606 inches 1
Below are the parameters that describe the performance curve of this specific pump: Hydraulic Head in ft 4430 3000 1500
Actual Flow Rate Speed in rpm Shaft power in hp in bbl/d 2152 500 110 2342 500 83 2456 500 50
In order to add a PCP to the PROSPER database, select | Design | Database | PCP | Pumps | Add and enter the pump data as done below:
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Select | Plot to generate the pump performance curve:
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Select | Main to conclude this task. 3.1.30.3Adding a Sucker Rod to the database The following rod data were obtained from the pump supplier: Rod Manufacturer : Rod Name : Rod Inside Diameter : Rod Outside Diameter : Rod Linear Density : Young's Modulus : Thermal Expansion :
Tutorial29 Rod 1 1 1.5 16 30602964 7.78E-06
(inches) (inches) (lb/ft) (psi) (1/deg F)
Select | Design | DataBase | Sucker Rods | Add and populate the screen as below:
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Should an invalid error message appears for the Young modulus value, then select | Done | Cancel | Cancel | Units | Units and then extend the maximum value allowed for the Young modulus to 15E10 psi:
Afterwards, select | Main | DataBase | Sucker Rods | Add and complete the addition of PROSPER Manual
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the rod to the database as done below:
Select | Main to complete this task. 3.1.30.4Input Data for PCP-Design For a SRP- design, the following data sets are needed: - PVT data, - Well equipment data - Reservoir data - SRP- design parameters 3.1.30.4.1 Fluid Properties Solution GOR:
100 scf/stb
Oil Gravity:
13 API
Specific gas gravity:
0.67 (Air =1)
Water salinity:
100000 ppm
CO2, N2, H2S content
0%
Pb, Rs & Bo Correlation:
Glaso
Oil Viscosity Correlation:
Beal et al
3.1.30.4.2 Well Equipment Data
3.1.30.4.2.1 Deviation Survey
Measured Depth in ft
True Vertical Depth in ft
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0
0
4000
4000
3.1.30.4.2.2 Surface Equipment
The surface pipes are not included in this tutorial. 3.1.30.4.2.3 Downhole Equipment
Equipme Measure Tubing Tubing nt Type d Depth ID Inside Roughne ss
Tubin Tubing Casin Casing g OD Inside g ID Inside Roughnes Roughnes s s
ft
inches
inches
inches inches
inches inches
Xmas
0
N/A
N/A
N/A
N/A
N/A
N/A
Tubing
4000
2.89
0.0012
3.5
0.0012
8.3
0.0012
3.1.30.4.2.4 Geothermal Gradient
Measured Depth in ft
Static Ambient Temperature
0
60
4000
160
Overall Heat Transfer Coefficient: 8 Btu/h/ft2/F 3.1.30.4.2.5 Average Heat Capacities
The default average heat capacity values will be used for this tutorial. 3.1.30.4.3 Inflow Performance Relation Reservoir Model Reservoir Pressure Reservoir Temperature Water Cut Total GOR Compaction Permeability Reduction Model: Relative Permeability: Productivity Index:
PROSPER Manual
PI Entry 1900 psig 160 degF 80 % 100 No No 2.5 stb/d/psi
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3.1.30.4.4 PCP-Design parameters Pump depth:
3500 ft
Maximum OD:
7 inches
Gas separator efficiency:
0%
Pump Wear Factor:
0%
Design Rate:
2500 stb/d
Rod Number:
ROD99/04
Water cut:
80%
Total GOR:
100 scf/stb
Top Node Pressure:
100 psig
Total Rod length:
3500 ft
Pipe Correlation:
Beggs and Brill
Tubing Correlation:
Petroleum Experts 3 - suitable for viscous oils
3.1.30.5Step by step procedure
3.1.30.5.1 PROSPER Well model set-up · Model options From the main menu click Options | Options and make the following changes: Artificial lift method: Progressive Cavity Pump Artificial lift type: Sucker Rod Drive
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Select | Done | PVT Input Data to enter the fluid properties: · PVT Data Solution GOR:
100scf/stb
Oil Gravity:
13 API
Specific gas gravity:
0.67 (Air =1)
Water salinity:
100000 ppm
CO2, N2, H2S content
0%
Pb, Rs & Bo Correlation:
Glaso
Oil Viscosity Correlation:
Beal et al
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Select | Done to complete the PVT data entry section. From the main menu select System | Equipment | All | Edit for the equipment data entry: · Equipment Data - Deviation survey Measured Depth in ft
True Vertical Depth in ft
0
0
4000
4000
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Select | Done to proceed to the surface equipment screen: · Surface Equipment
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Choke Method: ELF Temperature of surroundings: 60 degF Overall Heat Transfer: 8 Btu/h/ft2/F Select | Done to proceed to the down hole equipment screen: · Downhole Equipment Equipme Measure Tubing Tubing nt Type d Depth ID Inside Roughne ss
Tubin Tubing Casin Casing g OD Inside g ID Inside Roughnes Roughnes s s
ft
inches
inches
inches inches
inches inches
Xmas
0
N/A
N/A
N/A
N/A
N/A
N/A
Tubing
4000
2.89
0.0012
3.5
0.0012
8.3
0.0012
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Select | Done to continue with the geothermal gradient: · Geothermal gradient Measured Depth in ft
Static Ambient Temperature
0
60
4000
160
Overall Heat Transfer Coefficient: 8 Btu/h/ft2/F
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Select | Done to continue with the | Average heat capacities: · Average heat capacities
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Select | Done | Done to complete the equipment data entry. From the main PROSPER screen, select | System | Inflow Performance and make the following entries: Reservoir Model Reservoir Pressure Reservoir Temperature Water Cut Total GOR Compaction Permeability Reduction Model: Relative Permeability: Productivity Index:
PI Entry 1900 psig 160 degF 80 % 100 No No 2.5 stb/d/psi
Select Input Data to enter the well productivity index of 2.5 stb/d/psi:
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In order to visualise the inflow curve, select | Calculate:
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Select | Main to complete the model set-up. 3.1.30.5.2 PCP Design procedure In order to start the PCP design, select | Design | Progressive Cavity Pump and then populate the screen as follow: Pump depth:
3500 ft
Maximum OD:
7 inches
Gas separator efficiency:
0%
Pump Wear Factor:
0%
Design Rate:
2500 stb/d
Rod Number:
ROD99/04
Water cut:
80%
Total GOR:
100 scf/stb
Top Node Pressure:
100 psig
Total Rod length:
3500 ft
Pipe Correlation:
Beggs and Brill
Tubing Correlation:
Petroleum Experts 3 - suitable for viscous oils
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Afterwards, select | Calculate | Calculate to trigger the key pump design performance:
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The next step is to select | Done | Design and then select the pump and the rod as done below:
Select | Done | Done and this completes the PCP design
3.1.30.5.3 PCP sensitivity calculation In the following, we will sensitize on pump speed: 100, 200, 300, 400 and 500 rpm: For this, select | Calculation | System (Ipr+Vlp) | 3 Variables and make the following changes: Top Node Pressure: 100 psig Water Cut: 80% Total GOR: 100 scf/stb Surface Equipment Correlation: Beggs and Brill Vertical Lift Correlation: Petroleum Experts 3 Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow PROSPER Manual
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Select | Continue | Select the variable "Pump speed" and enter the sensitivity values as done below:
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Now proceed with | Continue | Calculate | OK | Plot | System Plot | Variables to select the variables of interest:
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Select | Done afterwards to see the system plot:
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Select | Finish to return to the previous menu where the numerical values of the system calculation are displayed:
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Note that one can scroll through the various sensitivity variables and the screen is update automatically. Select | Main and this completes this tutorial.
3.1.31 Tutorial 30: Modelling Diluent Injection into an oil well File: ~/samples/PROSPER/T30_DiluentInjection.OUT In this example we will install diluent injection at the bottom of the production tubing string. The objectives of this example are: · Create a new PROSPER file and set up the file options. · Perform a system calculation to investigate diluent injection on well performance. 3.1.31.1Statement of the Problem The purpose of this tutorial is to show how to quantify the impact of diluent injection rate on well production rate. The following steps will be carried out during this tutorial:
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· Create a PROSPER model · Perform a System Calculation with the following boundary conditions:
Well Head Flowing pressure:
75 psig
Water Cut:
95%
Total GOR:
1500 scf/stb
Vertical Lift Correlation:
Petroleum Experts 3
3.1.31.2Input Data To model diluent injection in an oil well using PROSPER, the following data sets are needed: - Produced Fluid and diluent PVT data, - Well equipment data - Reservoir data - Diluent injection depth and diluent injection rate 3.1.31.2.1 Produced Fluid & Diluent PVT The properties of both produced fluid and diluent fluid are required. Produced Fluid PVT: Solution GOR:
150 scf/stb
Oil Gravity:
25 API
Specific gas gravity:
0.67 (Air =1)
Water salinity:
70 000 ppm
CO2, N2, H2S content
0%
Pb, Rs & Bo Correlation:
Glaso
Oil Viscosity Correlation:
Beal et al
Diluent Fluid PVT: Specific gravity of diluent fluid:
10 API
Diluent FVF at 185 degF and 2250 psig:
1 rb/stb
Diluent viscosity at 185 degF and 2250 psig:
0.3 cp
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It should be noted that when available, a full description of the diluent fluid PVT at different pressure and temperature can be entered as look-up table in PROSPER. 3.1.31.2.2 Well Equipment Data · Deviation Survey
Measured Depth in ft
True Vertical Depth in ft
0
0
8000
8000
· Surface Equipment NONE · Downhole Equipment
Equipme Measure Tubing Tubing nt Type d Depth ID Inside Roughne ss
Tubin Tubing Casin Casing g OD Inside g ID Inside Roughnes Roughnes s s
ft
inches
inches
inches inches
inches inches
Xmas
0
N/A
N/A
N/A
N/A
N/A
Tubing
8000
1.995
0.0006
2.375 0.0006
6
0.0006
N/A
· Geothermal gradient Measured Depth in ft
Static Ambient Temperature
0
45
8000
185
Overall Heat Transfer Coefficient: 8 Btu/h/ft2/F · Average Heat Capacities The default average heat capacity values will be used for this tutorial. © 1990-2011 Petroleum Experts Limited
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3.1.31.2.3 Inflow Performance Data Reservoir Model Reservoir Pressure Reservoir Temperature Water Cut Total GOR Compaction Permeability Reduction Model: Relative Permeability: Productivity Index:
PI Entry 2800 psig 185 degF 90 % 1500 scf/stb No No 2.7 stb/d/psi
3.1.31.2.4 Diluent Injection Data Measured depth:
Diluent
Injection 6000 ft, 6500 ft, 7000 ft, 7500 ft & 7800 ft
Diluent Injection rate:
10 values from 0 stb/d with 50 stb/d increment
3.1.31.3Step by step procedure
3.1.31.3.1 PROSPER Well model set-up · Model options From the main menu click Options | Options and make the following changes: Artificial lift method: Diluent Injection Artificial lift type: Annular Injection - Tubing Production
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Select | Done | PVT Input Data to enter the fluid properties: · PVT Data The properties of both produced fluid and diluent fluid are required. Produced Fluid PVT: Solution GOR:
150 scf/stb
Oil Gravity:
25 API
Specific gas gravity:
0.67 (Air =1)
Water salinity:
70 000 ppm
CO2, N2, H2S content
0%
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Pb, Rs & Bo Correlation:
Glaso
Oil Viscosity Correlation:
Beal et al
To enter the diluent properties, select | Properties in the bottom right corner of the screen Diluent Fluid PVT: Specific gravity of diluent fluid:
10 API
Diluent FVF at Pres and Tres:
1 rb/stb
Diluent viscosity at Pres and Tres:
0.3 cp
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Because the the diluent lookup PVT contains a single point in a single table, the program will use the same FVF and viscosity throughout. If more points are entered, the algorithm will interpolate to find the viscosity and formation volume factor of the diluent as function of pressure and temperature. Select | Main to complete the data entry in the PVT section. From the main menu select System | Equipment | All | Edit for the equipment data entry: · Equipment Data - Deviation survey Measured Depth in ft
True Vertical Depth in ft
0
0
8000
8000
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Select | Done to proceed to the surface equipment screen: · Surface Equipment
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Choke Method: ELF Temperature of surroundings: 60 degF Overall Heat Transfer: 8 Btu/h/ft2/F Select | Done to proceed to the down hole equipment screen: · Downhole Equipment Equipme Measure Tubing Tubing nt Type d Depth ID Inside Roughne ss
Tubin Tubing Casin Casing g OD Inside g ID Inside Roughnes Roughnes s s
ft
inches
inches
inches inches
inches inches
Xmas
0
N/A
N/A
N/A
N/A
N/A
Tubing
8000
1.995
0.0006
2.375 0.0006
6
0.0006
N/A
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Select | Done to continue with the geothermal gradient: · Geothermal gradient Measured Depth in ft
Static Ambient Temperature
0
45
8000
185
Overall Heat Transfer Coefficient: 8 Btu/h/ft2/F
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Select | Done to continue with the | Average heat capacities: · Average heat capacities
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From the main PROSPER screen, select | System | Inflow Performance and make the following entries: Reservoir Model Reservoir Pressure Reservoir Temperature Water Cut Total GOR Compaction Permeability Reduction Model: Relative Permeability: Productivity Index:
PI Entry 2800 psig 185 degF 90 % 1500 scf/stb No No 2.7 stb/d/psi
Select Input Data to enter the well productivity index of 2.7 stb/d/psi:
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In order to visualize the inflow curve, select | Calculate:
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Select | Main to return to the main PROSPER screen. · Diluent injection data Select | System | Diluent Injection and populate the screen as done below: Measured depth:
Diluent
Diluent Injection rate:
Injection 6000 ft 10 values from 0 stb/d with 50 stb/d increment
Here a constant diluent injection of nil stb/d will be entered. This constant injection rate PROSPER Manual
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will be overwritten when sensitizing in the variable diluent injection rate during any subsequent calculation. Likewise, the dilluent injection depth is a sensitivity variable during the system calculations. Select | Done to complete the model set-up. 3.1.31.4Calculating Sensitivites To run system calculations, select Calculation | System (Ipr + Vlp) 3-Variable : Well Head Flowing pressure:
75 psig
Water Cut:
95%
Total GOR:
1500 scf/stb
Vertical Lift Correlation:
Petroleum Experts 3
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Select | Continue, choose the sensitivity variables and enter the following data:
Measured depth:
Diluent
Diluent Injection rate:
PROSPER Manual
Injection 6000 ft, 6500 ft, 7000 ft, 7500 ft & 7800 ft 10 values from 0 stb/d with 50 stb/d increment
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Select | Continue | Calculate | OK and then use the thumb buttons to review the tabular results:
Select | Plot | System Plot to see the graphical solution (to zoom in on the plot, left click and drag a box over the solution area):
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An alternative representation of the results would consist in displaying the flow rate as function of diluent injection rate. For this, select | System | Sensitivity | Variables amd make the following selections:
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Select | Done and the following graphical representation is displayed:
Two main conclusions can be drawn from the sensitivity plot: - the deeper the injection depth, the higher the flow rate. - for each injection depth, there is an optimum diluent inject rate, which is the maximum on each curve. Select | Main. This completes this tutorial.
3.1.32 Tutorial 31: Modelling Multiphase Pump with PROSPER File: ~/samples/PROSPER/T31_MultiphasePumpOnSeabed.OUT Multi-phase pumps enable non-processed well stream fluids to be boosted, providing a benefit to improving well performance. Multi-phase pump application also benefits deep water installations. 3.1.32.1Statement of the Problem In tutorial 2, a PROSPER well model was built for a naturally flowing oil. In tutorial 3, the model was updated with PVT calibration. In tutorial 20, the well model was matched against actual well test data. This tutorial 31 is built on tutorial 20. The well has now been in production for some time. Reservoir pressure has declined, water cut has increased, free gas is being produced and well deliverability has reduced. © 1990-2011 Petroleum Experts Limited
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To improve well productivity, the a multiphase pump will be installed at the well head to booster the production. 3.1.32.2Model Set Up From the main menu click Options | Options and select the following options: Artificial Lift Method:
Multiphase Pump
Type:
Framo Pumps
From the main menu select System | Inflow Performance and make the following changes to the IPR data: Reservoir Pressure Water Cut GOR: PROSPER Manual
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Introducing multiphase booster pump and riser From the main menu select System | Equipment and click on All | Edit and complete the following sections: · The deviation survey will not be changed. Select Done to move to the surface equipment section · Enter just 50 ft of pipe between the pump and the pump followed by 1000 ft of riser with an internal diameter of 6 inches.
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Ambient temperature: 50 degF Overall Heat Transfer Coefficient: 8 Btu/h/ft2/F Select | Plot to visualize the topography of the piping system:
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Select Finish | Main to revert to the main PROSPER screen. Select | Finish | Done and ensure that the well head is at 1000 ft as done below:
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Equally, the geothermal gradient needs to include a point at the well head depth of 1000 ft:
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Select | Main to return to the PROSPER main screen. Afterwards, select System | MultiPhase Pumps and enter the following data:
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Select Done to return to the main PROSPER screen.
3.1.32.3Calculating Sensitivies To run sensitivities on the selected pump for e.g. different reservoir pressures, water cuts, etc., the System (Ipr + Vlp) 3-Variable calculation will be used that can be selected via the Calculation menu option. Enter the following data: Top Node Pressure:
1000 psig
Water Cut:
50%
Total GOR:
1000
Rate Method:
User Selected
Rate generation method:
Linear Spacing
First value:
1000 stb/d
Last value:
20 000 stb/d
Number
20
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This is how the screen looks like once the rates have been generated or populated by hand:
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·
Click Continue and enter the following sensitivity data:
Click Continue | Calculate.
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Using the thumb buttons on the tabular results screen, one can observe that as the power available increases the the flow rate increases. This is better demonstrated with the | Sensitivity button and by selecting liquid rate under | Variables:
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multi-phase pump. Different pumps can be evaluated by returning to the main PROSPER screen and selecting System | MultiPhase Pumps then selecting a different pump from the Current Pump drop-down dialogue box and re-running the system calculation to evaluate well performance and multi-phase pump selection.
3.1.33 Tutorial 32: Trouble-shooting a gas lifted well File: ~/samples/PROSPER/T32_GasLiftQuickLook.OUT The main objectives of this example are to show how to analyse a well test for a gaslifted oil well.
3.1.33.1Statement Of The Problem The gas lifted well model constructed in tutorial 23 has been in production for some time. It is required to: - Analyse the well test results - Find out the most likely point of injection
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3.1.33.2Input Data The response of a gas lifted well depends upon: - Fluid response (PVT), - Reservoir response (IPR), - Tubing response and - Valve response. The valve response depends upon valve characteristics and casing head pressure. Changing operational circumstances can cause an unloading valve to open. When an unloading valve opens, the lift gas will take the path of least resistance and enter into the tubing at shallower depth. This will in turn reduce the efficiency of the gas lift. For this reason, a different approach is suggested to analyse artificially lifted systems in general, and gas lifted wells in particular. This approach is called the "Quicklook technique" in PROSPER. The purpose of the quicklook technique is to isolate the various components affecting the well response, PVT, IPR, VLP and valve response so that individual and crossanalysis can be conducted. For this, independent pressure gradients are computed in opposite directions. In case the test is fully consistent it should be possible to predict the well head flowing pressure starting from the reservoir pressure and vice-versa. If the gradient from the well head to the sandface is different from the the gradient from the sandface to the well head, then the model is inconsistent with the test data. A rigorous and coherent analysis needs to be performed to come up with the most logical and probable explanation for such inconsistency. 3.1.33.2.1 PROSPER well model This tutorial is built upon tutorial 23. For the beginner, it is recommended to review tutorial 23 before continuing with this one. 3.1.33.2.2 Well test results for Quicklook A recent well test was conducted with the following results: Flowing Well Head Pressure: 350 psig Flowing Well Head Temperature: 171 degF Gross Liquid Rate: 8530 stb/d Water Cut: 80% Measured Total Gas Rate ( produced + 5.7 MMscf/d injected lift gas): Estimated Gas lift injection rate: 4 MMscf/d Measured Casing Head Pressure: 1460 psig Gas Lift injection - orifice size: 32/64 inches © 1990-2011 Petroleum Experts Limited
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Gas Lift injection - measured orifice depth:
6161 ft
3.1.33.2.3 Gas Lift Valves Data Beside the well test data, detailed gas lift valve data are required to perform a quicklook. The information needed is listed below: Valve Type
Measured Depth in ft
Port Size in R value /64 inches
Dome Pressure in psig
Casing Sensitive
2975
22
0.038
1228
Casing Sensitive
4835
22
0.147
1195
Casing Sensitive
5885
22
0.26
1178
3.1.33.3Step by Step Procedure · Opening the PROSPER file Open the PROSPER file "Tutorial_23.out" · Review the PROSPER file It is recommended to perform the PROSPER model review in the following order: - PVT data / PVT matching parameters - IPR data - VLP matching parameters - Valve parameters: depth, size · Enter the well test data From the main screen of PROSPER, select | Matching | Quicklook and populate the screen with the well test data:
Flowing Well Head Pressure: Flowing Well Head Temperature: Gross Liquid Rate: Water Cut: Measured Total Gas Rate ( produced + injected lift gas): PROSPER Manual
350 psig 171 degF 8530 stb/d 80% 5.7 MMscf/d
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Gas injection rate:
4 MMscf/d
Measured Casing Head Pressure: Gas Lift injection - orifice size: Gas Lift injection - measured orifice depth:
1460 psig 32/64 inches 6161 ft
1298
Vertical Flow Correlation: Petroleum Experts 2 Dome Pressure Correction (above 1200 psig): Yes From this screen, select | Valve to enter the valve parameters if they are not already present: · Enter the gas lift valve data
Valve Type
Measured Depth in ft
Port Size in R value /64 inches
Dome Pressure in psig
Casing Sensitive
2975
22
1228
0.038
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Casing Sensitive Casing Sensitive
4835
22
0.147
1195
5885
22
0.26
1178
Select | Done to exit this screen. If down hole measurements (static and flowing) are available, they can be entered under the | Down hole Tab:
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In this example, the static reservoir pressure was estimated to be 3500 psig at the time the flow test was conducted. · Generate a Quicklook plot In order to generate a quicklook plot, select | Calculate | Calculate | OK | Plot and here is what shows:
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· Analyzing the results of the quicklook plot It can be seen that the gradients do not overlay. This means that the model does not behave in a manner consistent with the well test. This means that either the model is faulty or the well test data are incorrect or possibly model and well test are both wrong. Since multiple parameter combinations can lead to an inconsistency between model and well test data, there is no unique solution and no unique approach to reconcile well test with model.Which ever approach is taken needs to be coherent to be credible. The following method generally leads to a sensible solution if the well test data are reliable along with the multiphase correlation selected: a) Compare the calculated GOR with the PVT model Under the results section in the bottom right box, the quicklook has computed a free GOR of 596.48 scf/stb based upon the user enter total gas rate and the lift gas injection rate. The reservoir has a bubble point pressure of 2500 psig and the current static reservoir pressure is estimated at 3500 psig. This means that the reservoir is still highly undersaturated and hence no free gas can exist within the reservoir. The theoretical produced associated gas rate can be computed from the solution GOR, the water cut and the liquid rate to be 0.682 MMscf/d. The gas injection rate can then be computed by subtracting the associated gas from the total gas rate and this is how the inputs would then look like: PROSPER Manual
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The gas injection rate is then 5.0176 MMscf/d. This is valid only under the assumption that the liquid rate and the water cut are correct. This is what the quicklook plot shows once the total gas production is reconciled with the PVT:
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One can now read that the free GOR is o scf/stb and the solution GOR 400 scf/stb as one would expect. b) Find the deepest valve through which gas lift injection is possible by iteration Using the casing pressure, the gas gradient in the annulus is computed. This the curve labeled "Casing Measured". Using the flowing well head pressure, the flowing gradient in the tubing is computed, This is the curve labeled "Tubing Measured". At a gas lift injection point, the annulus pressure should be equal to the sum of tubing pressure and pressure drop across the valve. In the plot above, an injection depth of 6161 ft was assumed. At the assumed injection depth, it can be seen that the pressure gradient in the annulus is lower that the tubing pressure gradient. This is the reason why the message "INJECTION NOT POSSIBLE" is displayed. It can also be seen On the plot, it reads "injection not possible" at the assumed injection depth because the measured casing pressure One needs to check if it is possible to inject at the next shallower valve, that is at a measured depth of 5885 ft:
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This is how the quicklook plot now looks like:
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One can see that the message "Injection is not possible" has disappeared. This suggests that the valve at a depth of 5885 ft is likely open. c) Matching the casing head pressure by iterating on the orifice size One can see that the theoretical casing head pressure does not match the measured casing head pressure. To match the measured casing head pressure, one can iterate on the orifice size. In this example, an equivalent orifice size of 54/64 inch does the job:
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This is how the quick look plot now looks like:
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d) Find the IPR parameter (reservoir pressure, permeability, skin, and so on) that can be modified to reasonably predict the well head flowing pressure starting from the reservoir pressure. Now any unknown is confined to the IPR section. In this specific case, two possible solutions can be explored: change the well productivity index or the reservoir pressure. In this case, the reservoir pressure will be used as tuning parameter. In reality, the user will have to judge which parameter is suitable to be used as tuning parameter. From the quicklook plot, select | Done | Done | Down Hole and then enter a reservoir pressure of 3660 psig at 8000 ft measured depth:
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Afterwards, select | Done | Calculate | Calculate | OK | Plot and this is how the quicklook plot now looks like:
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One can clearly see that a match is achieved. The engineer will need to confirm the findings with additional information. This completes this tutorial.
3.1.34 Tutorial 33: Trouble-shooting an ESP-lifted well File: ~/samples/PROSPER/T33_ESPQuicklook.OUT The main objectives of this example is to show how to analyse the performance of well that is fitted with an electrical submersible pump.
3.1.34.1Statement Of The Problem The ESP-lifted well designed in tutorial 26 has been producing for a while. The well has been tested and the results recorded. It is required to: - analyse the test results, - compare the actual well performance with the PROSPER well model, - reconcile both well test and simulation results and - predict the performance of the well if the pump operating frequency is increased to 70 Hertz. PROSPER Manual
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3.1.34.2Well Test Data The following well test data have been recorded Parameter Tubing Head Pressure: Well Head Flowing Temperature: Liquid Rate: Water Cut: Static Reservoir Pressure: Produced GOR: Measured Pump depth: Operating frequency during test: Length of cable: Gas separation Number of stages Pump wear factor: Gauge pressure at pump inlet: Gauge pressure at pump discharge: Current used: Surface voltage: Power at surface:
Value 250 psig 174 dgeF 9750 stb/d 90% Unknown - estimated to be less than 4000 psig 250 scf/stb 7000 ft 55 Hertz 7000 ft 0% - no separator installed 49 0 2170 psig 3300 psig optional optional optional
3.1.34.3Strategy The overall strategy to analyse the performance of an ESP-lifted well can be broken down in three phases: Phase 1: Build a PROSPER model if this is not already done Phase 2: Collect and critically analyse the well test data Phase 3: Reconcile well test data with model Phase 4: Use model to run scenarios, to optimize well performance. 3.1.34.3.1 Phase 1: Build a PROSPER model For this tutorial, a PROSPER model has already been built. It is the PROSPER file "Tutorial_26.out". We will load the PROSPER file "Tutorial_26.out" and save it as "Tutorial_33.out". 3.1.34.3.2 Phase 2: Collect and analyse well test data Here are the well test data reported:
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Parameter Tubing Head Pressure: Well Head Flowing Temperature: Liquid Rate: Water cut: Static Reservoir Pressure: Produced GOR: Measured Pump depth: Operating frequency during test: Length of cable: Gas separation Number of stages Pump wear factor: Gauge pressure at pump inlet: Gauge pressure at pump discharge: Current used: Surface voltage: Power at surface:
Value 250 psig 174 dgeF 9750 stb/d 90% Unkown - estimated to be less than 4000 psig 250 scf/stb 7000 ft 55 Hertz 7000 ft 0% - no separator installed 49 0 2170 psig 3300 psig optional optional optional
Given the fact that the bubble point pressure is 2500 psig and the reservoir pressure is estimated to be above 2500 psig, then the produced GOR must be equal to the solution GOR of 400 scf/stb. Therefore, for the analysis the following test data set will be used:
Parameter Tubing Head Pressure: Well Head Flowing Temperature: Liquid Rate: Static Reservoir Pressure: Produced GOR: Measured Pump depth: Operating frequency during test: Length of cable: Gas separation Number of stages Pump wear factor: Gauge pressure at pump inlet: Gauge pressure at pump discharge: Current used: Surface voltage: Power at surface:
PROSPER Manual
Value 250 psig 174 dgeF 9750 stb/d Unknown - estimated to be less than 4000 psig 400 scf/stb 7000 ft 55 Hertz 7000 ft 0% - no separator installed 49 0 2170 psig 3300 psig optional optional optional
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3.1.34.3.3 Phase 3: Analyse and match test to well model Preliminary considerations For a naturally flowing well, the well response is the combination of: - Fluid response (PVT), - Reservoir response (IPR) and - Tubing response (VLP correlation). In the case of an artificially lifted well, a fourth component is added to the mix: the response of the artificial lift system, here the Electrical Submersible Pump. Precisely because of this fourth component that complicates the analysis, a different technique is proposed in PROSPER to trouble-shoot artificially lifted wells: the Quicklook technique. In order to use the Quicklook technique, a preferred multiphase correlation needs to be selected. If the well test was conducted with down hole pressure measurements, then the multiphase flow correlation selection can be made using the current well test data. If on the other hand no down hole pressure measurements are available then one should select a a multiphase correlation like Petroleum Experts 2 that was found to be generally reliable in the past for the Quicklook analysis. Procedure to analyse the well test From the main screen of PROSPER, select | Matching | Quicklook and enter the well test data:
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Parameter Tubing Head Pressure: Well Head Flowing Temperature: Liquid Rate: Water Cut: Static Reservoir Pressure:
Value 250 psig 174 dgeF 9750 stb/d 90% Unknown - estimated to be less than 4000 psig Produced GOR: 400 scf/stb Measured Pump depth: 7000 ft Operating frequency during test: 55 Hertz Length of cable: 7000 ft Gas separation 0% - no separator installed Number of stages 49 Pump wear factor: 0 Gauge pressure at pump inlet (7000 ft): 2170 psig Gauge pressure at pump discharge (7000 3300 psig ft): Current used: optional Surface voltage: optional Power at surface: optional
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Now select | Calculate | Calculate | Plot and the following pressure traverses are displayed:
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In the quicklook pressure traverses are calculated from top to bottom and vice-versa. If the assumptions regarding well and ESP conditions (e.g. pump frequency, wear factor, water cuts, wellhead pressure, IPR etc.) are correct, the two calculated traverses will overlay. In addition, an energy balance is performed across the electrical system allowing surface voltage and power to be calculated and compared to measured data. In the plot above, a few key points need to inspected: pump duty, multiphase correlation and inflow performance relationship. Test Analysis The pump duty is the difference between the discharge pressure and the inlet pressure of the pump. In the plot above, one can see that the top down traverse matches the pump inlet pressure and the pump outlet pressure indicating that: - the selected multiphase correlation remains valid for the analysis - the theoretical and measured pump duty are identical, indicating that the pump is performing according to the published pump performance curve. - however, the bottom-up pressure traverse does not match the top-down pressure traverse. Specifically, the predicted WHFP is higher than the measured one. This indicates that either the reservoir pressure is either too high or the productivity index is too high. In this particular case, it was suspected that the reservoir pressure of 4000 psig was overestimated. PROSPER Manual
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Therefore, one can iterate on the reservoir pressure to match the well test. In this particular case, entering a Static Bottom Hole Pressure (Pr)in the QuickLook well test data section of 3800 psig does the job:
NOTE: It will be necessary to update the reservoir pressure value in the IPR section.
3.1.34.3.4 Phase 4: Use model to run what-if scenarios In order to run sensitivity of pump operating frequency, select | Calculation | System (VL+IPR) | 3 Variables:
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Now select | Continue | and select the pump operating and reservoir pressure as sensitivity variable:
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Frequency: 55 & 70 Hertz Pressure: 3800 psig
Now proceed with | Continue | Calculate | OK | Plot | System Plot and the following plot is shown:
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This example shows that the well can produce up to 13370 stb/d if the frequency is increased to 70 Hertz. In order to see the pump plot, select | OK | Solution Details | Pump Plot Below is what the pump plot shows. It indicates at 70 Hz, the pump would still be operating within its recommended operating envelope:
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3.1.35 Tutorial 34: Trouble-shooting an HSP-lifted well File: ~/samples/PROSPER/T34_HSPQuicklook.OUT The main objectives of this example is to show how to analyse the performance of well that is fitted with an hydrauic submersible pump.
3.1.35.1Statement Of The Problem A HSP-lifted well has been producing for a while. The well has been tested and the results recorded. It is required to: - analyse the test results, - compare the actual well performance with the PROSPER well model, - reconcile both well test and simulation results 3.1.35.2Well Test Data The following well test data have been recorded:
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Parameter Tubing Head Pressure: Liquid Rate: Water Cut: Static Reservoir Pressure: Produced GOR: Measured Pump depth: Operating speed during test: Power Fluid Rate: Number of pump stages Pump wear factor: Gauge pressure at pump inlet: Gauge pressure at pump discharge: Number of turbine stages: Pump Turbine
Value 350 psig 7211 stb/d 90% Unknown - estimated to be less than 3000 psig 400 scf/stb 7500 ft 5965 rpm 6340 stb/d 35 0 2255 psig 3855 psig 54 Clyde Union TP145A Clyde Union T-60 (TEST) - A
3.1.35.3Strategy The overall strategy to analyse the performance of an HSP-lifted well can be broken down in three phases: Phase 1: Build a PROSPER model if this is not already done Phase 2: Collect and critically analyse the well test data Phase 3: Reconcile well test data with model 3.1.35.3.1 Phase 1: Build a PROSPER model For this tutorial, a PROSPER model has already been built. It is the PROSPER file "T34_HSPQUICKLOOK_START.out". Load the PROSPER file "T34_HSPQUICKLOOK_START.out". 3.1.35.3.2 Phase 2: Collect and analyse well test data Here are the well test data reported:
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Parameter Tubing Head Pressure: Liquid Rate: Water Cut: Static Reservoir Pressure: Produced GOR: Measured Pump depth: Operating speed during test: Power Fluid Rate: Number of pump stages Pump wear factor: Gauge pressure at pump inlet: Gauge pressure at pump discharge: Number of turbine stages: Pump Turbine
1322
Value 350 psig 7211 stb/d 90% Unknown - estimated to be less than 3000 psig 400 scf/stb 7500 ft 5965 rpm 6340 stb/d 35 0 2255 psig 3855 psig 54 Clyde Union TP145A Clyde Union T-60 (TEST) - A
Given the fact that the bubble point pressure is 2500 psig and the reservoir pressure is estimated to be above 2500 psig, then the produced GOR must be equal to the solution GOR of 400 scf/stb. 3.1.35.3.3 Phase 3: Analyse and match test to well model Preliminary considerations For a naturally flowing well, the well response is the combination of: - Fluid response (PVT), - Reservoir response (IPR) and - Tubing response (VLP correlation). In the case of an artificially lifted well, a fourth component is added to the mix: the response of the artificial lift system, here the Hydraulic Down Hole Pump. Precisely because of this fourth component that complicates the analysis, a different technique is proposed in PROSPER to trouble-shoot artificially lifted wells: the Quicklook technique. In order to use the Quicklook technique, a preferred multiphase correlation needs to be selected. If the well test was conducted with down hole pressure measurements, then the multiphase flow correlation selection can be made using the current well test data. If on the other hand no down hole pressure measurements are available then one should select a a multiphase correlation like Petroleum Experts 2 that was found to be generally reliable in the past for the Quicklook analysis. Procedure to analyse the well test From the main screen of PROSPER, select | Matching | Quicklook and enter the well test data. © 1990-2011 Petroleum Experts Limited
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Note that the produced GOR was corrected to be consistent with fluid PVT and estimated reservoir pressure. Therefore, the initial GOR of 400 scf/stb is to be used.
Now select | Calculate | Calculate | Plot and the following pressure traverses are displayed:
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In the Quicklook pressure traverses are calculated from top to bottom and vice-versa. If the assumptions regarding well and HSP conditions (e.g. pump frequency, wear factor, number of stages, water cuts, wellhead pressure, IPR etc.) are correct, the two calculated pressure traverses will overlay Test Analysis For the analysis of an HSP lifted well, one shall simultaneously inspect pump performance, multiphase correlation and inflow performance relationship. The pump performance can be evaluated by comparing the theoretical pressure gain across the pump with the actual / recorded pressure gain across the very same pump. Such a comparison is easily performed if there are down hole gauges at the inlet and the outlet of the pump. In this example, downhole pressure gauges are available. By inspecting the downward gradient (green curve), which is based purely on test data, it is possible to see that the outlet gauge pressure measurement is closely matched this because the multiphase flow correlation was previously mQtched to lab data. However, looking the dP given by the pump is higher than the difference between the measured inlet and outlet pressure, which may indicate that the manufacturer's performance has to be corrected to reproduce the actual pump dP.
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This can be achieved by modifying the pump wear factor in the Quicklook input data. After a few iterations (change the wear factor, then run the Quicklook calculation and check the plot), one can find a wear factor of 0.05 to match the pump dP
repeating the Quicklook calculation, it is possible to verify that the measured PROSPER Manual
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(downward, green curve) pump dP is now matching:
With respect to the upward gradient, which is based on the model IPR, this can be corrected to match the experimental pressures by adjusting any of the parameters of the IPR. In particular, it was suspected that the reservoir pressure have dropped since production start and is expected to be less than 3000 psig. Therefore, one can iterate on the reservoir pressure to see if the well test can be matched with a reasonable static reservoir pressure valid at the time of the well test. For this, we will reduce the reservoir pressure to 2910 psig:
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Now select | Calculate | Calculate | OK | Plot and this is how the quicklook plot looks like the one below:
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One can see that a perfect match was achieved between top down and bottom-up pressure traverse. It essential to keep in mind that multiple solutions do exist. In this case, one can match the well test by altering the skin or permeability for instance. The right parameter to alter in order to match the well test is in the end a matter of engineering judgment to be made by the engineer on the basis of his knowledge of the well and the relevant operating circumstances. At last, by looking at the plot results table (HSP Quicklook results), it is possible to verify that the calculated pump speed (which is the one required to have the highest overall efficiency), is 5964 rpm, close to the test data (5965 rpm). This result confirms that the results obtained are correct. Save the file as "T34_HSPQUICKLOOK.Out".
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3.1.36 Tutorial 35: Trouble-shooting a SRP-lifted well There is no specific PROSPER file associated with this tutorial. The tool widely used to analyse the performance of wells equipped with sucker-rod pumps is the dynamometer card, often referred to as card. It represents rod load versus rod displacement. The card has a "normal shape". The deviation from this normal shape can reveal potential pumping problems. In the pictures below: Fo is the differential load on the plunger MPT is the maximum plunger travel and EPT, the effective plunger travel A few typical shapes are presented below for an anchored tubing:
Anchored Tubing
Description
Unanchored Tubing
This is the idealised shape of the dynamometer card for a nnormally functioning pump. Pump is full of liquid without gas.
Leaking travelling valve or excessive plunger slippage
Leaking standing valve
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Severe fluid pound, well is being pump off.
Gas interference is causing loss of effective pump travel
Pump is taping at the bottom of stroke in the case of anchored tubing. In the case of unanchored tubing, pump is tapping on top of strokes.
These shapes are just basic as in the reality different effects may overlap. Experience and knowledge of the specific operating conditions will be required to make a successful diagnostic.
3.1.37 Tutorial 36: Flow assurance calculations File: ~/samples/PROSPER/T36_FlowAssurance.OUT The main objectives of this tutorial is to show how to set up a PROSPER model for flow assurance studies. Even though this tutorial is based upon a retrograde condensate fluid, a similar approach can be used for any other fluid type: oil or gas.
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3.1.37.1Statement Of The Problem A well is to be drilled to produce retrograde condensate. Fluid data (PVT), reservoir data (IPR), surface and down hole equipment description (VLP) are provided. It is required to: - estimate the initial flow rate against a well head flowing pressure of 1500 psig - rigorously model the temperature distribution along the flow path to investigate potential hydrates formation - inspect flow regimes and slug characteristics along the flow path. 3.1.37.2Input Data
PVT Data A comprehensive lab report was made available and the experimental lab results were calibrated using PVTp, the compositional fluid characterization package developed by Petroleum Experts. The output of the calibration is a *.PRP (Tutorial_36.prp) file that can be imported directly into any Petroleum Experts' application. * *
Petroleum Experts - PRP Export File
* * *Export File Signatur e *#Petex PRP *Export File Version *#1 3 * *
* *
!!!!!! FILE DETAILS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!! !!!!!!!!!! !!!!!!!!!!!! !!!!!! !! FILE NAME: C:\IPM Files\Tutorial_36.prp Exported: Wed Sept 02
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* 10:07:52 2009 *
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
* * *
Equation Type 0 - Peng Robinson 1 - SRK 0
* * * *
Number of Components Number of Lumped Components - Set to 0 if No Lumping Present
* 16
0
* * * *
Mole Critical Critic Acce Molec Specif Critic Volu Boilin Parac Omeg Omeg Costa Cost Compo al ntric ular ic al me g hor aA aB ld ald nent Perc Temper Press Facto Weigh Gravit Volu Shift Point Volu Accen Fact Nam ent ature ure r t y me me tric e
* * *
perc degree F psig lb/lb. Gravit l/kg. degre F l/kg. ent s mole y mole es mole ------ --------- ------- ------- -------- ------- ------- ------- ------- ------- ------- ------- ------- ------ -------------- ------ ------- ------- ------- ------- ------- ------- ------- ------- ------- ------- ------- -------0.31 477.3 0.039 28.01 1.026 89.80 -0.154 - 60.4 0.45720.0777 0 0.039 N2 233.104 26 013 320.3 4 96 5 2.33 87.692 1058. 0.239 44.01 1.101 93.89 78 0.45720.0777 0 0.239 CO2 26 989 0.100 109.2 4 96 2 1 68.73 658.3 0.011 16.04 0.415 99.20 70 0.45720.0777 0 0.011 C1 116.518 81 017 0.167 258.7 4 96 17 9 12.37 89.798 693.6 0.099 30.1 0.546 148.2 0.069 115 0.45720.0777 0 0.099 C2 51 999 273 127.3 4 96 9 5.01 206.006 602.6 0.153 44.1 0.585 203.0 155 0.45720.0777 0 0.153 C3 83 002 0.131 43.69 4 96 83 1.3 274.694 514.3 0.183 58.1 0.6 263.0 - 10.85 181.5 0.45720.0777 0 0.183 IC4 © 1990-2011 Petroleum Experts Limited
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* 6 1.41 305.294 535.9 0.199 58.1 63
0.6
0.6 369.806 468.3 0.227 72.2 0.621 62 0.8 385.592 474.8 0.251 72.2 0.63 28 0.96 454.1 425.0 0.299 86.2 0.664 08 1.032583.705 360.7 0.307 118.20 0.790 76 72 32 5 52 1.449594.655 353.6 0.369 142.31 0.816 95 64 64 7 84 1.208604.783 349.9 0.436 168.37 0.841 79 71 39 1 45 0.649783.408 346.3 0.487 191.10 0.856 47 7 68 2 84 0.944899.659 334.0 0.541 214.67 0.870 22 34 38 7 44 0.894977.545 300.5 0.622 255.81 0.888 82 77 1 7 34
001 0.712 4 96 72 254.9 - 31.19 200 0.45720.0777 997 0.570 4 96 98 305.9 - 82.13 225 0.45720.0777 998 0.697 4 96 47 304.0 - 96.89 245 0.45720.0777 002 0.480 4 96 56 370.0 - 155.7 282.5 0.45720.0777 002 0.233 5 4 96 54 486.9 - 261.8 360.8 0.45720.0777 167 0.185 52 25 4 96 16 578.1 - 337.9 421.4 0.45720.0777 783 0.080 95 4 96 13 679.2 - 415.2 481.9 0.45720.0777 414 0.029 45 94 4 96 5 759.3 0.000 470.6 531.4 0.45720.0777 324 218 58 06 4 96 845.3 0.030 525.4 579.9 0.45720.0777 294 246 5 08 4 96 976.7 0.050 603.2 659.7 0.45720.0777 938 498 66 78 4 96
0 0.199 NC4
0 0.227
IC5
0 0.251 NC5
0 0.299
C6
0 0.307 C7::C9 32 0 0.369 C10:: 64 C11 0 0.436 C12:: 39 C13 0 0.487 68 0 0.541 38 0 0.622 1
C14:: C14 C15:: C16 C17:: C20
* *
Binary Interaction Coefficients
* * * *
Only non-sero BICs are exported and imported WARNING : the number of non-sero BICs in IPM is currently6 limited to 450 Any values over this limit will be lost
* *
Number of non-sero BICs to be written or read
* 1 PROSPER Manual
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* *
Only first half of array is exported - values wil lbe copied to second half
* 15 2
0.05
* *
Volume shift flag
* 1 * *
Separators T, P
* 2 1 80
200
60
0
* *
Refe Temperature renc e
* 255 * *# End of file
Equipment Data Deviation Survey Measured Depth in ft 0 12000
True Vertical Depth in ft 0 12000
Surface Equipment
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Equipme Length in True nt type ft Vertical Depth in ft
Pipe Outside Diameter in inches
Pipe Roughne Inside ss in diameter inches in inches
Platform / N/A Top node
0
N/A
N/A
N/A
Riser
2000
2000
10.75
10.5
0.0006
Tie Back
5000
1500
6.625
6.375
0.0006
Down hole Equipment Equipmen Measured Tubing ID Tubing OD Tubing Inside t Type Depth in ft in inches in inches Roughness in inches Xmas Tree 1500
N/A
N/A
N/A
St. Steel 11500 (25%)
3.826
4.5
0.0006
Temperature Data Air temperature: 60 degF Humidity: 70% Air velocity:0.1 ft/s · Formation temperature Gradient Formation measured depth in ft
Sea temperature in degF
0
60
1500
45
2000
40
12000
255
· Sea temperature gradient PROSPER Manual
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Mean sea level with respect to origin: 0 ft Seabed with respect to origin: 2000 ft TVD from mean sea Sea temperature in Sea velocity in ft/s level in ft degF 0
60
0.1
1500
45
0.1
2000
40
0.1
Drilling and Completion
Drilling Hole Depth Diamet in ft er in inches
Casing Shoe Depth in ft
Casing Outsid e Diamet er in inches
Specifi c Casing weight in lb/ft
Top Cemen t Depth in ft
Casing Top Depth in ft
Mud Densit y in lb/ gal
10000
12
10000
10
60
1500
1500
12
12000
9
12000
7
40
1500
1500
12
Model Convection in Mud: No Completion Fluid Liquid Type: Brine Completion Fluid Density: 10 lb/gal Completion Fluid Gas Type: Produced Gas Packer Depth: 11 500 ft Mid Production Depth: 12 000 ft Annulus level: 1500 ft Lithology Format Bottom Shalin Porosit Perme Rock In-situ ion depth ess in y in ability consist Fluid type in ft fractio fractio in mD ency
Salinity in ppm
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Fixed 11900 Value Sandst 12000 one
n N/A
n N/A
N/A
N/A
0.1
0.25
50
consoli Gas dated
N/A
N/A 100000
Reservoir Temperature: 255 degF Reservoir Pressure: 6000 psig IPR Data IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Total GOR: Compaction Permeability Reduction model: Skin model: Permeability: Reservoir Thickness (True stratigraphic thickness): Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered: Mechanical skin:
Petroleum Experts 6000 psig 255 degF 0 stb/MMscf 7940.38 scf/stb No Enter skin by hand 50 mD 50 ft 300 acres 31.6 0.354 ft 30 ft 1 days 0.25 0.25 Calculated Total permeability +5
Note: The Petroleum Experts' IPR method uses pseudo-pressure. It is PROSPER Manual
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transient and accounts for relative permeability effects. Please consult the online help for more details.
3.1.37.3Step by step procedure Options Launch PROSPER, select | Options | Options and make the following choices: Fluid description - Type:
Retrograde Condensate
Fluid description - Method:
Equation Of State
Hydrates:
Enable Warning
Calculation type - Model:
Enthalpy Balance
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Select | EOS setup and make the following changes EOS Model:
Peng Robinson
Optimisation Mode:
Medium
Optimise Repeat Calculation:
Yes
Full Composition:
Yes
Allow Lumping:
No
Reference Temperature:
60 degF
Reference pressure:
0 psig
Phase detection Method:
Advanced
Path to surface - Separator Calc Use Separator Train Method: First stage:
200 psig and 80 degF
Second stage:
0 psig and 60 degF
Target GOR method:
Use Separator fluids
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Select | OK | Done to complete this. PVT In order to enter the PVT data, select | PVT | Input Data and then select | Import ... PRP © 1990-2011 Petroleum Experts Limited
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to download the PRP file "Tutorial_36.prp" located in the PROSPER samples directory. The following message would appear:
Select | OK | Accept changes to complete the PRP file import:
Enter the water salinity of 100000 ppm. Hydrate curve generation From the PVT screen, a hydrate curve can be generated and stored within the PROSPER file. During the calculations, PROSPER will flag if the operating conditions (Pressure and Temperature) are in hydrate formation region or not. To generate and store the hydrate curve, select | Hydrates | Generate Hydrates Pressure Values PROSPER Manual
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Afterwards, select | OK and enter the temperature range from 40 degF to 100 degF in 10 steps.
Select | Calculate | OK | Plot and the hydrate curve can be visualized:
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Select | Finish | Done | Done to complete the PVT data import and the hydrate curve generation. Equipment Data In order to enter the equipment data, select | System | Equipment | All | Edit and enter the deviation survey as shown below: Deviation Survey Measured Depth in ft 0 12000
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True Vertical Depth in ft 0 12000
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Select | Done to proceed with the surface equipment data entry: Surface Equipment Label
Equipm Length True ent type in ft Vertical Depth in ft
Pipe Pipe Inside Roughne Outside diameter in ss in Diameter in inches inches inches
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Platform
Manifold N/A
0
N/A
N/A
N/A
Riser
Line Pipe
2000
2000
10.75
10.5
0.0006
Tie Back Line Pipe
5000
1500
6.625
6.375
0.0006
Note that pipes may be buried and / or insulated. Select | Done to proceed with the down hole equipment Down hole Equipment Equipment Type
Measured Depth in ft
Tubing ID in Tubing OD in Tubing Inside inches inches Roughness in inches
Xmas Tree
1500
N/A
N/A
N/A
3.826
4.5
0.0006
St.
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(25%)
Equally tubing may be insulated with concrete, foam, bitumen or any other user-defined material. Select | Done to enter the temperature data Temperature Data Air temperature: 60 degF Humidity: 70% Air velocity: 0.1 ft/s · Formation temperature Gradient Formation measured depth in ft
Sea temperature in degF
0
60 © 1990-2011 Petroleum Experts Limited
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1500
45
2000 12000
40 255
· Sea temperature gradient Mean sea level with respect to origin: 0 ft Seabed with respect to origin: 2000 ft
TVD from mean sea level in ft
Sea temperature degF
0
60
0.1
1500
45
0.1
2000
40
0.1
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in Sea velocity in ft/s
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Select | Done to enter the drilling and completion data Drilling and Completion Drilling in ft
Depth Hole Diameter in Casin inches g Shoe Depth in ft
Casin g Outsi de Diam eter in inche
Speci fic Casin g weigh t in lb/ ft
Top Ceme nt Depth in ft
Casin g Top Depth in ft
Mud Densi ty in lb/gal
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s 10000 12000
12 8.5
10000 10 12000 7
60 40
1500 1500
1500 1500
12 12
Model Convection in Mud: No Completion Fluid Liquid Type: Brine Completion Fluid Density: 10 lb/gal Completion Fluid Gas Type: Produced Gas Packer Depth: 11 500 ft Mid Production Depth: 12 000 ft Annulus level: 1500 ft
Select | Done to enter lithology Lithology
Formatio Bottom PROSPER Manual
Shalines Porosity Permeab Rock
In-situ
Salinity
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n type
depth in s in in ft fraction fraction
Fixed 11900 Value Sandston 12000 e
ility mD
in consiste Fluid ncy
N/A
N/A
N/A
N/A
N/A
0.1
0.25
50
consolida Gas ted
1350
in ppm N/A 100000
Reservoir Temperature: 255 degF Reservoir Pressure: 6000 psig
Select | Done | Done to return to the equipment data entry screen. It is possible to visualize the well bore schematic with | Summary | Draw Down hole:
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Select | Main and save the file to secure all the parameters entered so far in the model. In order to describe the well inflow performance relationship, select | System | Inflow relationship and make the following choices
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Total GOR: Compaction Permeability Reduction model: Skin model:
PROSPER Manual
Petroleum Experts 6000 psig 255 degF 0 stb/MMscf 7940.38 scf/stb No Enter skin by hand
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Now select | Input Data and enter the reservoir parameters as done below: Permeability: Reservoir Thickness (True stratigraphic thickness): Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered: Mechanical skin:
50 mD 50 ft 300 acres 31.6 0.354 ft 30 ft 1 days 0.25 0.25 Calculated Total permeability +5
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To enter the mechanical skin, select | Mech / Geom Skin and enter 5 as done below:
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At this stage, it is good practice to generate and display the IPR. This is achieved by selecting the | Calculate button:
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Select | Main and save the file to secure the data entries. System calculation This is a full enthalpy balance model with 16 components Peng-Robinson Equation of State model. Therefore, it will be computationally intensive. In order to perform the system calculation, select | Calculation | System | 3 Variables and make the following choices: Top Node Pressure:
1500 psig
Water Gas Ratio:
0 stb/MMscf
Total GOR:
7940.38
Time since Production started:
1 day
Surface Equipment Correlation:
Beggs and Brill
Vertical Lift Correlation:
Petroleum Experts 2
Solution Node:
Bottom node
Rate Method:
Automatic Linear
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Left Hand Intersection:
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Disallow
Select | Continue | Continue and Calculate and be patient as the model is computationally intensive.One shall keep in mind the various effects that make the model computationally intensive: - The fluid description is compositional. Therefore loads of flash calculations are required. - The enthalpy balance solves simultaneously for pressure and temperature as opposed to the rough approximation where both temperature and pressure are calculate separately. - The enthalpy balance always starts from known conditions (reservoir) and iterates to match the user-entered well head flowing pressure. Multiple iterations might be needed for each rate to achieve convergence. All the above explain why advanced thermal calculations with fully compositional fluid description take longer to run. For this example, at the end of the calculation, the following results are displayed: © 1990-2011 Petroleum Experts Limited
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The well would produce around 57 MMscf/d of gas and 7250 stb/d of oil.. The hydrate flag (H) shows for each flow rate. This means that hydrate mitigation should be considered. Below, 12 MMscf/d, the well would fall below the Turner stability criteria. This is shown with the the "T". Above 100 MMscf/d, erosional velocity is exceeded in the well. In order to visualise what is happening inside the tubing, the tie back and the riser, one selects | Sensitivity PvD | Continue | Calculate and here all the calculation details are displayed. Taitel- Duckler Flow Regime
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By selecting the node 60 for instance, the Taitel-Dukler flow regime map is displayed with the severe slugging line :
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In this case, the operating point is beyond the severe slugging line. From the above Sensitivity PvD results screen, scrolling the bar at the bottom to the right, one can see the columns for hydrates, velocities pigging and slug parameters, etc. Select | Done to return to the Sensitivity - Pressure Vs depth screen. Select | Main to return to the main Prosper screen. This completes this tutorial. .
3.1.38 Tutorial 37: Pipeline Only Modelling & matching File: ~/samples/PROSPER/T37_PipelineMatching.OUT The main objectives of this example are to show: · How to set up a PROSPER model for a pipeline or riser only system without a well connect to it · How to enter the PVT data · How to describe the pipeline equipment · How to match a flow test through a pipeline · How to use the calibrated model to predict the pipe performance under PROSPER Manual
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changing conditions 3.1.38.1Statement Of The Problem A 5000 ft ft long pipe carries fluid (uphill) over an elevation of 250 ft. The pipe was subject to a flow test. It is required to: - Build a pipeline only PROSPER model - Select the most suitable multiphase correlation for this pipe - Match the correlation to the test results - Use the calibrated model to predict the pipe performance under changing operating conditions 3.1.38.2Input Data For a pipeline only model, the following inputs are required: - Fluid PVT (black oil or compositional) - Pipe description (simple: rough approximation / advanced: enthalpy balance or improved approximation) 3.1.38.2.1 Fluid PVT data The basic available PVT data are: Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
Bubble point pressure (Pb):
2500 psig at 200 degF
Oil FVF at Pb and 200 degF:
1.214 rb/stb
Oil viscosity at Pb and 200 degF:
1.01 cp
3.1.38.2.2 Pipeline Data The pipeline data are given below:
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Parameter Value Pipeline Length: 5000 ft Pipeline Internal Diameter: 6 inches Pipe Inside Roughness: 0.0006 inches Temperature Of Surroundings: 50 degF Overall Heat Transfer Coefficient: 1.5 Btu/h/ft2/F Total pipe hight above origin (inlet depth): -250 ft Fluid Inlet temperature: 100 degF
3.1.38.2.3 Flow test results Here are the results from the flow test: Pipe Flow Test data
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Parameter Match Point Comment (optional): Pipe Outlet Pressure: Pipe Outlet Temperature: water Cut: Gross liquid rate: Pipe Inlet Pressure: Gas Oil Ratio: GOR free: Pipe inlet Temperature:
1362
Value Flow test from 01/01/2010 250 psig 90 degF 50% 25000 stb/d 500 psig 400 scf/stb 0 scf/stb 100 degF
3.1.38.3Step by step procedure
3.1.38.3.1 PROSPER Model Setup · Model options From the main menu click Options | Options and make the following changes: Calculation type: Pipeline Only
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Select | Done | PVT Input Data to enter the fluid properties: · PVT Data The fluid properties are to be entered and matched as follow: Fluid PVT: Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
PROSPER Manual
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
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To enter the fluid properties at non-standard conditions, select | Match Data and populate the screen as follow:
Parameter Solution GOR: Bubble point pressure (Pb):
Value 400 scf/stb 2500 psig at 200 degF
Oil FVF at Pb and 200 degF:
1.214 rb/stb
Oil viscosity at Pb and 200 degF:
1.01 cp
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Select | Done | Regression | Match All | OK | Parameters to inspect the statistical results of the PVT matching.
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Parameter 1 is a multiplier whereas Parameter 2 is a shift. Therefore the best correlation is the one with a parameter 1 equal to unity and parameter 2 equal to zero. For the oil FVF matching, Parameter 4 is the multiplier above the bubble point pressure whereas Parameter 4 is the shift above the bubble point pressure. Looking at the statistics above, we will select the Glaso black oil correlation for the bubble point calculation, solution GOR and oil formation volume. For the viscosity, the Beal et al correlation will be selected. For this select |Done |Done and verify that the Glasa and the Beal correlation have effectively been chosen:
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Select | Main to complete the data entry in the PVT section. · Equipment Data - Fluid inlet temperature From the main menu select System | Equipment and then enter the fluid inlet temperature of 100 degF:
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Next select | All | Edit for the equipment data entry: · Equipment Data - Surface Equipment Choke Method: ELF Coordinate system: Height, Distance From Origin Note: The change in coordinate system is optional. Any other coordinate is fine as long as it captures properly pipe topography: pipe length and elevation. Parameter Pipeline Length: Pipeline Internal Diameter: Pipe Inside Roughness: Temperature Of Surroundings: Overall Heat Transfer Coefficient: Total pipe height above origin (inlet depth): Fluid Inlet temperature:
Value 5000 ft 6 inches 0.0006 inches 50 degF 1.5 Btu/h/ft2/F -250 ft 100 degF
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A few notes: - If the coordinate system Height, Distance From Origin is selected, then the first equipment type changes from manifold to Xmas-tree. - Elevation is the opposite of depth. This is why the sign of the height changes is the coordinate system changes to TVD and Length:
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The results are not affected by the coordinate system selected. Select | Done to continue with the | Average heat capacities: · Average heat capacities
Select | Done | Done to complete the pipe only PROSPER model.
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3.1.38.3.2 Pipe Performance Matching In order to match the pipe performance, select | Matching | Matching | Pipeline and enter the flow test data as done below: Pipe Flow Test data Parameter Match Point Comment (optional): Pipe Outlet Pressure: Pipe Outlet Temperature: Water Cut: Gross liquid rate: Pipe Inlet Pressure: Gas Oil Ratio: GOR free: Pipe inlet Temperature:
Value Flow test from 01/01/2010 250 psig 90 degF 50% 25000 stb/d 500 psig 400 scf/stb 0 scf/stb 100 degF
The procedure to follow is very similar to tubing performance matching. The 4 steps to be taken are: - U value calibration - Correlation comparison - Multiphase Flow Correlation matching. - Multiphase Flow Correlation selection. PROSPER Manual
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· U value Calibration - optional From the flow test, the inlet and outlet temperature are known along with the mass flow rate. Therefore, there is an opportunity to check how the predicted outlet temperature compares with the reported outlet temperature. For this, select | Correlation Comparison | OK | Select any VLP correlation ( Fancher Brown/ Beggs and Brill / OLGAS 2P & PE4:
Now continue with | Calculate | Calculate | OK and then inspect the computed outlet temperature: © 1990-2011 Petroleum Experts Limited
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One can read in the 5th column a computed arrival temperature of round 98 degF, which is 8 degF higher that the measured outlet temperature. In order to match this, the U-value needs to be increased to in iterative fashion. For this select | Main | Done | System | Equipment | Surface Equipment and then change the overall heat transfer coefficient to 8.05 Btu/h/ft2/F as done below:
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Now select | Main | Matching | Matching | Pipeline. Afterwards, select | Correlation Comparison | OK | Calculate | Calculate | OK and a much better match of the arrival temperature have been achieved:
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· Correlation comparison Afterwards, select | Plot to visualize the pressure gradient in the pipe:
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One can see that PE4, PE5 and OLGAS 2P are the closest to the measured upstream pressure. Select | Main to get back to the "Surface Pipe Matching" screen.
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· Multiphase Flow Correlation Matching For the pipe match, select | Match | Match | Statistics to inspect the statistical results of the non-linear regression:
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· Multiphase Flow Correlation selection The parameter 1 is the gravity term multiplier whereas the parameter 2 is the friction term multiplier. Ideally, both should equal to unity and one can see here that both multipliers are very close indeed to unity. The statistics show that PE4, PE5 and OLGAS 2P have very similar performances. Since PE5 requires slightly less correction than PE4 and OLGAS 2P, the PE5 correlation will be selected for further calculations.
3.1.38.3.3 Sensitivity runs Next, we will perform sensitivity on the following parameters:
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Outlet Pressure:
250 psig
Water Cut:
50%
Total GOR:
400, 600, 800, 1000, 1200, 1400 & 1600 psig
Liquid Rate:
15 000 stb/d
To perform the sensitivity runs, select | Calculation | Gradient (Traverse) and make the appropriate changes as shown below:
Select | Continue and then choose the variable Gas Oil Ration from the drop-down menu:
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Select | Continue and select the OLGAS 2P multiphase correlation:
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Now select | Calculate | OK | Plot | Variables and start with the simplest plot:
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The following plot shows:
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Note that more specialized parameters can be selected and plotted with | Variables | Extended:
This is how for example the erosional velocity profile looks like in the pipe:
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Select | Main and this completes this tutorial.
3.1.39 Tutorial 38: Full enthalpy balance tutorial File: ~/samples/PROSPER/T38_EnthalpyBalance.OUT The main objectives of this example are to show: · How to set up a PROSPER model for a naturally flowing oil well · How to enter the PVT data · How to enter the IPR data · How to describe the down hole equipment · How to perform a system calculation (VLP + IPR) to estimate the well flow rate for a given WHFP. · How to generate a well performance curve · How to generate and export lift curves to GAP/MBAL/REVEAL or any third party software (Eclipse, VIP, ...)
3.1.39.1Statement Of The Problem A well is to be drilled to produce retrograde condensate from a depth of 15000 ft. Fluid data (PVT), reservoir data (IPR) and a detailed down hole equipment description © 1990-2011 Petroleum Experts Limited
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(VLP) are provided. It is required to : - Build a PROSPER well model - Use the model to estimate the flow rate against a well head flowing pressure of 2500 psig using the full enthalpy balance model. 3.1.39.2Input Data
3.1.39.2.1 PVT Data The basic available PVT data are: Parameter Separator Pressure: Separator temperature: Separator GOR: Separator gas gravity: Stock Tank GOR: Stock Tank gas gravity: Condensate gravity: Water to Gas Ratio: Water Salinity: Impurities (H2S, CO2 & N2): Dewpoint at reservoir temperature: Reservoir temperature: Reservoir Pressure:
Value 1500 psig 100 degF 9000 scf/stb 0.65 (air =1) 1000 scf/stb 0.85 (air =1) 60 API 0 stb/MMscf 40000 ppm None 6000 psig 300 degF 8000 psig
3.1.39.2.2 Equipment Data The enthalpy balance model is an advanced thermodynamic model that rigorously accounts for all heat transfer mechanisms taking place in and around the well bore. Therefore, it requires a detailed description of well and completion. 3.1.39.2.2.1 Deviation Survey
This is vertical well. Measured Depth in ft 0 15000
True Vertical Depth in ft 0 15000
3.1.39.2.2.2 Surface Equipment
In this tutorial, the surface equipment will not be modeled.
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3.1.39.2.2.3 Downhole Equipment
Equipment Type Measured Depth
Tubing ID Tubing OD
Tubing Inside Roughness
ft
inches
inches
inches
Xmas Tree
0
N/A
N/A
N/A
St. Steel (13%)
1000
4
5.5
0.0006
SSSV
1000
3.5
N/A
N/A
St. Steel (13%)
15000
4
5.5
0.0006
3.1.39.2.2.4 Temperature Data
Air temperature: 60 degF Humidity: 70% Air velocity:5 ft/s
· Formation temperature Gradient
Formation Measured Depth Static Formation Temperature in deg F in ft: 0 50 500 40 15000 300 Mean sea level with respect to origin: 200 ft Seabed with respect to origin: 500 ft · Sea temperature gradient
TVD from mean sea level Sea temperature in degF Sea velocity in ft/s in ft 0 300
50 40
3 3
3.1.39.2.2.5 Drilling and Completion Data
The drilling and completion data are give below:
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Drilling Hole Depth in Diameter ft in inches
Casing Shoe Depth in ft
Casing Outside Diameter in inches
Specific Casing weight in lb/ft
Top Cement Depth in ft
Casing Mud Top Density Depth in in lb/gal ft
700 3000 10000
36 26 17
700 3000 10000
30 20 13
93 65 72
200 200 5000
0 0 0
10 10 10
13000 15000
12 9
13000 15000
10 7
67 43
10000 12000
0 0
12 12
Completion Fluid Density: 8.5 lb/gal Completion Fluid Gas Type: Air Packer Depth: 14 500 ft Mid Production Depth: 14900 ft Annulus level: 50 ft 3.1.39.2.2.6 Lithology
Formatio Bottom Shalines Porosity Permeab Rock In-situ n type depth in s in in ility in consiste Fluid ft fraction fraction mD ncy
Salinity in ppm
Shale 14800 Sandston 15000 e
N/A 40000
N/A 0.2
N/A 0.15
N/A 15
N/A N/A consolida Gas ted
3.1.39.2.2.7 Databases for thermal properties
The default databases will be used in this tutorial without any modifications. 3.1.39.2.3 Reservoir Data PROSPER has around 20 different inflow models for retrograde condensate wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Total GOR: Compaction Permeability Reduction model: PROSPER Manual
Petroleum Experts 8000 psig 300 degF 0 stb/MMscf 9 000 scf/stb No May, 2011
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Skin model: Permeability: Reservoir Thickness (True stratigraphic thickness): Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered: Mechanical skin:
1388
Enter skin by hand 15 mD 200 ft 240 acres 31.6 0.41 ft 100 ft 1 days 0.15 0.25 Calculated Total permeability +5
Note: The Petroleum Experts' IPR method uses pseudo-pressure. It is transient and accounts for relative permeability effects. Please consult the online help for more details. 3.1.39.3Step by Step procedure Launch PROSPER and select | File | New to start this tutorial. 3.1.39.3.1 PROSPER Model Setup · Model options From the main menu click |Options | Options and make the following changes: Fluid Description - Fluid: Retrograde Condensate Calculation Type - Predict: Pressure and Temperature (offshore) Calculation Type - Model: Enthalpy Balance
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Note: In this example, the black oil model for retrograde condensate will be used. The user has the option of using a compositional fluid description method as well. Select | Done to complete this. · PVT Data From the main menu select | PVT | Input Data and make the following entries:
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Parameter Separator Pressure: Separator temperature: Separator GOR: Separator gas gravity: Stock Tank GOR: Stock Tank gas gravity: Condensate gravity: Water to Gas Ratio: Water Salinity: Impurities (H2S, CO2 & N2): Dewpoint at reservoir temperature: Reservoir temperature: Reservoir Pressure:
1390
Value 1500 psig 100 degF 9000 scf/stb 0.65 (air =1) 1000 scf/stb 0.85 (air =1) 60 API 0 stb/MMscf 40000 ppm None 6000 psig 300 degF 8000 psig
Select | Done to exit the PVT data entry screen.
· Deviation Survey Select | System | Equipment | All | Edit to enter the deviation survey:
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Measured Depth in ft 0 15000
True Vertical Depth in ft 0 15000
Select | Done to proceed to the surface equipment description screen: · Surface Equipment
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Select | Cancel to skip this screen and continue to the downhole equipment description: · Downhhole Equipment Equipment Type Measured Depth
Tubing ID Tubing OD
Tubing Inside Roughness
ft
inches
inches
inches
Xmas Tree
0
N/A
N/A
N/A
St. Steel (13%)
1000
4
5.5
0.0006
SSSV
1000
3.5
N/A
N/A
St. Steel (13%)
15000
4
5.5
0.0006
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Select | Done to proceed with the temperature data · Temperature Data Air temperature: 60 degF Humidity: 70% Air velocity:5 ft/s · Temperature Data - Formation temperature Gradient
Formation Measured Depth Static Formation Temperature in deg F in ft: 0 50 500 40 15000 300 Mean sea level with respect to origin: 200 ft Seabed with respect to origin: 500 ft · Temperature Data - Sea temperature gradient PROSPER Manual
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TVD from mean sea level Sea temperature in degF Sea velocity in ft/s in ft 0
50
3
300
40
3
Select | Done to proceed to the drilling and completion data · Drilling and Completion Data © 1990-2011 Petroleum Experts Limited
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Drilling Hole Depth in Diameter ft in inches
Casing Shoe Depth in ft
Casing Outside Diameter in inches
Specific Casing weight in lb/ft
Top Cement Depth in ft
Casing Mud Top Density Depth in in lb/gal ft
700
36
700
30
93
200
0
10
3000
26
3000
20
65
200
0
10
10000
17
10000
13
72
5000
0
10
13000
12
13000
10
67
10000
0
12
15000
9
15000
7
43
12000
0
12
Mud Convection: No Completion Fluid Type: Brine Completion Fluid Density: 8.5 lb/gal Completion Fluid Gas Type: Air Packer Depth: 14 500 ft Mid Production Depth: 14900 ft Annulus level: 50 ft
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Select | Done to proceed to the lithology data · Lithology
Formatio Bottom Shalines Porosity Permeab Rock In-situ n type depth in s in in ility in consiste Fluid ft fraction fraction mD ncy
Salinity in ppm
Shale
N/A
14800
N/A
N/A
N/A
N/A
N/A
Sandston 15000 e
0.2
0.15
15
consolida Gas ted
40000
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Select | Done to proceed to the databases for thermal properties. · Database for thermal properties
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Select | Reset | Done | Done to complete this section From the main screen, select | System | Inflow Performance and make the following entries: · Reservoir Data - IPR model selection IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Total GOR: Compaction Permeability Reduction model: Skin model:
Petroleum Experts 8000 psig 300 degF 0 stb/MMscf 9 000 scf/stb No Enter skin by hand © 1990-2011 Petroleum Experts Limited
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Select | Input Data to continue the IPR data input: Permeability: Reservoir Thickness (True stratigraphic thickness): Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered:
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Select the tab "Mech/Geom Skin" at the bottom left corner of the screen for the skin entry:
Mechanical skin:
+5
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At this stage, it is good practice to generate an IPR curve w ith | Calculate:
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Select | Main to complete the set-up of the PROSPER model. 3.1.39.3.2 System Calculation To run a system calculation, select Calculation | System (Ipr + Vlp) | 3 Variables and make the following entries: Top Node Pressure: 2500 psig Water Gas Ratio: 0 stb/MMscf Total GOR: 9000 scf/stb Time Since Production Started: 1 day
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Select | Continue | Continue | Calculate | OK and the results are displayed as follow:
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With | Plot | System Plot, the are displayed as follow:
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This concludes this tutorial. Select | Main to exit the screen.
3.1.40 Tutorial 39: Improved Approximation File: ~/samples/PROSPER/T39_ImprovedApproximation.OUT The main objectives is to show how to set-up the improved approximation, an advanced thermal model.
3.1.40.1Statement Of The Problem A well is to be drilled to produce retrograde condensate from a depth of 15000 ft. Fluid data (PVT), reservoir data (IPR) and a detailed down hole equipment description (VLP) are provided. It is required to : - Build a PROSPER well model - Use the model to estimate the flow rate against a well head flowing pressure of 2500 psig using the Improved Approximation model.
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3.1.40.2Input Data
3.1.40.2.1 PVT Data The basic available PVT data are: Parameter Separator Pressure: Separator temperature: Separator GOR: Separator gas gravity: Stock Tank GOR: Stock Tank gas gravity: Condensate gravity: Water to Gas Ratio: Water Salinity: Impurities (H2S, CO2 & N2): Dewpoint at reservoir temperature: Reservoir temperature: Reservoir Pressure:
Value 1500 psig 100 degF 9000 scf/stb 0.65 (air =1) 1000 scf/stb 0.85 (air =1) 60 API 0 stb/MMscf 40000 ppm None 6000 psig 300 degF 8000 psig
3.1.40.2.2 Equipment Data The Improved Approximation temperature model is an advanced thermodynamic model that rigorously accounts for all heat transfer mechanisms taking place in and around the well bore like the enthalpy balance model. The only difference between enthalpy balance and improved approximation is the way the overall heat transfer coefficient is found: in the former, overall heat transfer coefficient is computed by the model whereas it is user-entered in the latter. 3.1.40.2.2.1 Deviation Survey
This is vertical well. Measured Depth in ft 0 15000
True Vertical Depth in ft 0 15000
3.1.40.2.2.2 Surface Equipment
In this tutorial, the surface equipment will not be modeled. 3.1.40.2.2.3 Downhole Equipment
Equipment Type Measured Depth ft
Tubing ID Tubing OD
Tubing Inside Roughness
inches
inches
inches
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Xmas Tree
0
N/A
N/A
N/A
Tubing
1000
4
5.5
0.0006
SSSV
1000
3.5
N/A
N/A
Tubing
14800
4
5.5
0.0006
3.1.40.2.2.4 Temperature Data
Formation Depth in ft:
Measured Static Formation Heat Transfer Coefficient Temperature in deg F
0 500 3000 10000 14000 15000
50 40 80 210 280 300
2 2.5 2.5 3.8 4.8 5
3.1.40.2.3 Reservoir Data PROSPER has around 20 different inflow models for retrograde condensate wells. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study.
IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Total GOR: Compaction Permeability Reduction model: Skin model: Permeability: Reservoir Thickness (True stratigraphic thickness): Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered: PROSPER Manual
Petroleum Experts 8000 psig 300 degF 0 stb/MMscf 9 000 scf/stb No Enter skin by hand 15 mD 200 ft 240 acres 31.6 0.41 ft 100 ft 1 days 0.15 0.25 Calculated Total permeability May, 2011
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Mechanical skin:
1408
+5
Note: The Petroleum Experts' IPR method uses pseudo-pressure. It is transient and accounts for relative permeability effects. Please consult the online help for more details. 3.1.40.3Step by Step procedure Launch PROSPER and select | File | New to start this tutorial. 3.1.40.3.1 PROSPER Model Setup · Model options From the main menu click |Options | Options and make the following changes: Fluid Description - Fluid: Retrograde Condensate Calculation Type - Model: Improved Approximation
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Note: In this example, the black oil model for retrograde condensate will be used. The user has the option of using a compositional fluid description method as well. Select | Done to complete this. · PVT Data From the main menu select | PVT | Input Data and make the following entries:
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Parameter Separator Pressure: Separator temperature: Separator GOR: Separator gas gravity: Stock Tank GOR: Stock Tank gas gravity: Condensate gravity: Water to Gas Ratio: Water Salinity: Impurities (H2S, CO2 & N2): Dewpoint at reservoir temperature: Reservoir temperature: Reservoir Pressure:
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Value 1500 psig 100 degF 9000 scf/stb 0.65 (air =1) 1000 scf/stb 0.85 (air =1) 60 API 0 stb/MMscf 40000 ppm None 6000 psig 300 degF 8000 psig
Select | Done to exit the PVT data entry screen.
· Deviation Survey Select | System | Equipment | All | Edit to enter the deviation survey:
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Measured Depth in ft 0 15000
True Vertical Depth in ft 0 15000
Select | Done to proceed to the surface equipment description screen: · Surface Equipment
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Select | Cancel to skip this screen and continue to the downhole equipment description: · Downhole Equipment
Equipment Type Measured Depth
Tubing ID Tubing OD
Tubing Inside Roughness
ft
inches
inches
inches
Xmas Tree
0
N/A
N/A
N/A
Tubing
1000
4
5.5
0.0006
SSSV
1000
3.5
N/A
N/A
Tubing
14800
4
5.5
0.0006
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Select | Done to proceed with the temperature data · Formation Temperature Gradient
Formation Depth in ft
Measured Static Formation Heat Transfer Coefficient Temperature in degF
0
50
2
500
40
2.5
3000
80
2.5
10000
210
3.8
14000
280
4.8
15000
300
5
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Select | Done | Done to complete the equipment data entry. From the main screen, select | System | Inflow Performance and make the following © 1990-2011 Petroleum Experts Limited
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entries: · Reservoir Data - IPR model selection IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Gas Ratio: Total GOR: Compaction Permeability Reduction model: Skin model:
Petroleum Experts 8000 psig 300 degF 0 stb/MMscf 9 000 scf/stb No Enter skin by hand
Select | Input Data to continue the IPR data input: Permeability: Reservoir Thickness (True stratigraphic thickness): Drainage Area: Dietz shape factor: Well bore radius (Drill bit radius): Perforation interval: PROSPER Manual
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Time since production: Reservoir porosity: Connate water saturation: Non-Darcy Flow Factor: Permeability entered:
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1 days 0.15 0.25 Calculated Total permeability
Select the tab "Mech/Geom Skin" at the bottom left corner of the screen for the skin entry:
Mechanical skin:
+5
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At this stage, it is good practice to generate an IPR curve w ith | Calculate:
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Select | Main to complete the set-up of the PROSPER model. 3.1.40.3.2 System Calculation To run a system calculation, select Calculation | System (Ipr + Vlp) | 3 Variables and make the following entries: Top Node Pressure: 2500 psig Water Gas Ratio: 0 stb/MMscf Total GOR: 9000 scf/stb Time Since Production Started: 1 day
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Select | Continue | Continue | Calculate | OK and the results are displayed as follow:
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With | Plot | System Plot, the are displayed as follow:
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This concludes this tutorial. Select | Main to exit the screen.
3.1.41 Tutorial 40: SPOT tutorial File: ~/samples/PROSPER/T40_SPOT.OUT The main objectives of this tutorial is to show how to use the SPOT inflow model within PROSPER.
3.1.41.1Statement Of The Problem A well is to be drilled to produce oil from an oil reservoir. Fluid data (PVT), reservoir data (IPR) and down hole equipment description (VLP) are provided. Using SPOT (Shell Perforation Optimisation Tool), it is requested to estimate the initial IPR and the initial flow rate against a WHFP of 300 psig.
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3.1.41.2PVT Input Data The basic available PVT data are: Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
3.1.41.3System Equipment Input Data The system equipment input section is sub-divided into 5 sub-sections: - deviation survey - surface equipment - down hole equipment - Geothermal gradient and - Average heat capacities 3.1.41.3.1 Deviation survey In PROSPER, the deviation survey can have its origin anywhere: well head, sea-bed, platform, RKB and so on ... The key thing is to describe all the equipment in the well in a manner that is consistent with respect to the origin selected. The well head depths does not have to coincide with the origin of the deviation survey.
Measured Depth in ft 0 8000
True Vertical Depth in ft 0 8000
3.1.41.3.2 Surface Equipment All equipment located downstream of the well head are part of the surface equipment. The surface equipment can include: well head chokes, risers, flow lines, fittings, and so on. In this example the surface equipment will not be modelled. 3.1.41.3.3 Down Hole Equipment The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment
Measured
Internal
Roughness
inRate multiplier
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type
depth in (down to) Xmas Tree (Well0 Head) Tubing 7800 Casing 8000
ft diameter inches N/A 3.992 8.3
in inches N/A
N/A
0.0018 0.0018
1 1
3.1.41.3.4 Static Geothermal Gradient The geothermal gradient expresses the rate of increase in temperature per unit depth. The geothermal gradient is independent of the well flow rate. When using the rough approximation temperature prediction method, the geothermal gradient is entered versus measured depth. PROSPER internally converts the measured depth into true vertical depth and it is the temperature gradient based upon the true vertical depth that is used during the calculation.
Measured Depth in ft 0 8000
Static temperature in deg F 70 200
The overall heat transfer coefficient is 8 btu/h/ft2/F. Note: The overall heat transfer (also called U value) is a composite number that captures the different heat transfer mechanisms taking place: conduction, convection and radiation. It can be thought of as the inverse of the thermal resistance in the surroundings of the wellbore. 3.1.41.3.5 Average Heat Capacities Here the default average heat capacities will be used: Phase Oil: Gas: Water:
Heat Capacity in Btu/lb/F 0.53 0.51 1
3.1.41.4Reservoir Input Data PROSPER has around 20 different inflow models. The IPR model selection depends upon the purpose of the study, the suitability of the particular model and the data available for the study. PROSPER Manual
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IPR model: Static Reservoir Pressure: Reservoir Temperature: Water Cut: Total GOR:
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SPOT 4000 psig 200 degF Calculated based upon relative permeability and userentered water saturation 400 scf/stb
Spot options and input data Lp Correlation Type:
Conventional
Calculate Non-Darcy skin:
No
Activity:
New Well
Well type:
Vertical
Inflow Equation:
Fetkovich
Log Data Input:
None available
Perforating Method:
Single Run
Invasion Method:
No Invasion
Sanding Model:
None
Crushed Zone Model:
Entered
Lower Completion type:
Cased and Perforated
Pressure Transform:
apply to gas wells only
Use down hole standoff:
No
Enter Gun per layer:
No
Use SPOT IPR extensions:
Yes
Crushed Zone Permeability 0.1 Factor: Crushed Zone Thickness:
1.2 inches
Spot options - Deviation survey
Measured depth in ft
True Vertical depth if ft
8000
8000
8250
8250
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Spot options - Layers Data & Gun system
Well bore radius:
0.354 ft
Drainage Radius:
2000 ft
Perforation Efficiency:
1 (fraction)
Top Measured Depth of pay:
8000 ft
Bottom Measured depth of pay:
8200 ft
Layer Pressure:
3600 psig
Under Balance Pressure:
100 psi
Overburden Pressure Gradient:
1 psi/ft
Water saturation:
0.3 (fraction)
Bottom hole (reservoir) Temperature:
200 degF
Kv/Kh:
0.1 (fraction)
Downhole (reservoir) Rock type:
Sandstone
Gun System:
2007 Predator XPLS by Baker with 6 spf and 60 degrees phasing
Spot options - Completion
Completion type:
Casing
Outer Diameter:
8.5 inches
Casing weight:
9 lb/ft
Material:
J-55
Top Measured Depth:
8000 ft
Bottom Measured Depth:
8200 ft
Drift Diameter*:
8 inches
Holdup Depth*:
8250 ft
Notes: The drift diameter is the inside diameter (ID) that the pipe manufacturer guarantees per specifications. Note that the nominal inside diameter is not the same as the drift diameter but is always slightly larger. The drift diameter is used by the well planner to determine what size tools or casing strings can later be run through the casing, whereas the nominal inside diameter is used for fluid volume calculations such PROSPER Manual
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as mud circulating times and cement slurry. The holdup depth is the depth at which a tool of a specific size can no longer pass through the well bore.
3.1.41.5Step by Step The following pages provide a step-by-step procedure that will lead to the solution of the problem: - construct a PROSPER model for a producing oil well using SPOT for the IPR - use the PROSPER well model to estimate the flow rate against a WHFP of 300 psig - compare the performance of the well with different gun systems - inspect the calculation results at log scale 3.1.41.5.1 System Options Here, one simply select | File | New if a PROSPER file is already open. Otherwise, simply select |Options | Options and make the following choices Fluid: Oil and Water Predict: Pressure and Temperature (on land)
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Select | Done to complete this step. 3.1.41.5.2 PVT data Input In order to enter the PVT data, simply select |PVT|Input Data and populate the screen as shown below:
Parameter Solution GOR: Oil Gravity: Gas gravity: Water salinity: Impurities (CO2, N2, H2S):
PROSPER Manual
Value 400 scf/stb 30 API 0.75 (Air =1) 80000 ppm None
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Select | Done to complete this step.
3.1.41.5.3 Saving the PROSPER file Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes. To save a file, simply select | File | Save as ... Afterwards, simply browse to the place where the file is to be saved. It is suggested to save the file as *.OUT file. The rest is self-explanatory. 3.1.41.5.4 System Equipment Description In order to describe the hardware in / around the well bore (this is what the system equipment is), simply select | System | Equipment (Tubing etc) | All
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Now by selecting | Edit, the software will take the user through all the screens necessary to input the equipment data starting with the deviation survey 3.1.41.5.4.1 Deviation Survey
Here are the deviation survey data for this vertical well:
Measured Depth in ft 0 8000
PROSPER Manual
True Vertical Depth in ft 0 8000
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Note: It is possible to input or import a large deviation survey table into PROSPER. A filtering algorithm is implemented that will select up to 20 of the most relevant data points describing the well trajectory. For this, the | Filter button located on the top right of this screen is to be used. Select | Done and the next screen labeled Surface Equipment will follow. 3.1.41.5.4.2 Surface Equipment
This model will not include any surface equipment. Therefore, one simply need to select | Cancel to skip this step: © 1990-2011 Petroleum Experts Limited
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Selecting the "Cancel" button located on the top left of the screen will take the user to the next screen: the down hole equipment description screen. 3.1.41.5.4.3 Down Hole Equipment
The down hole equipment include the tubings, casings, nipples, Sub-surface Safety valves, ...
Equipment type
Measured depth in (down to) Xmas Tree (Well0 Head) Tubing 7800 Casing 8000
PROSPER Manual
Internal ft diameter inches N/A 3.992 8.3
Roughness in inches
in Rate multiplier
N/A
N/A
0.0018 0.0018
1 1
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The deepest entry in the down hole equipment section is the datum depth for the static reservoir pressure that will be entered in the IPR section. It is recommended to take the top perforation as the reference depth for the static reservoir pressure. This would mean that the down hole equipment description shall stop at the top of the perforation. This is also true for multiple-zone completion because the pressure drop between the zones will be taken into account by the appropriate Inflow model (multi-layer IPR model with dP or multilateral IPR model). Select | Done to proceed to the next screen: the geothermal gradient. 3.1.41.5.4.4 Geothermal gradient
The data available are:
Measured Depth in ft 0 8000
Static temperature in deg F 70 200 © 1990-2011 Petroleum Experts Limited
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The overall heat transfer coefficient is 8 btu/h/ft2/F.
Select | Done to proceed to the average heat capacity screen. 3.1.41.5.4.5 Average Heat Capacities
The default average heat capacity values will be used for this example
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Note: The | Default button will reset any user-entered values. With | Done the entry screen of the Equipment data section will be accessed:
It is now possible to visualise a sketch of the well bore with | Summary | Draw Down hole. 3.1.41.5.4.6 Equipment Summary
From the Equipment Data screen, one can see a summary of the well bore description with | Summary:
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If one then selects | Draw Down hole a sketch of the well bore is drawn:
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Select | Main to exit the screen.
3.1.41.5.4.7 Saving the PROSPER file
Like working with any other computer program, it is good practice to save the file frequently in order to avoid data loss in case the computer crashes for instance. To save a file, simply select | File | Save and then simply answer YES to overwriting the file. 3.1.41.5.5 Inflow Performance Relation (IPR) For the selection of the IPR model, simply select | System | Inflow Performance and make the appropriate choices as follows: IPR model: Reservoir Temperature: Water Cut: Total GOR:
SPOT 200 degF Calculated based upon relative permeability and userentered water saturation 400 scf/stb
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Select | Input Data and start the the SPOT IPR data entry with the left tab OPTIONS"
"SPOT
Spot options and input data Lp Correlation Type:
Conventional
Calculate Non-Darcy skin:
No
Activity:
New Well
Well type:
Vertical
Inflow Equation:
Fetkovich
Log Data Input:
None available
Perforating Method:
Single Run
Invasion Method:
No Invasion
Sanding Model:
None
Crushed Zone Model:
Entered
Lower Completion type:
Cased and Perforated
PROSPER Manual
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Pressure Transform:
apply to gas wells only
Use down hole standoff:
No
Enter Gun per layer:
No
Use SPOT IPR extensions:
Yes
1438
Crushed Zone Permeability 0.1 Factor: Crushed Zone Thickness:
1.2 inches
Select the deviation Survey tab at the bottom left corner of the Options screen to enter the well trajectory across the reservoir: Spot options - Deviation survey
Measured depth in ft
True Vertical depth if ft
8000
8000
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8250
8250
Select | Done to complete the data entry for this screen. To move forward, select the tab "Layers" to describe the reservoir and select the gun system: Spot options - Layers Data & Gun system PROSPER Manual
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Well bore radius:
0.354 ft
Drainage Radius:
2000 ft
Perforation Efficiency:
1 (fraction)
Top Measured Depth of pay:
8000 ft
Bottom Measured depth of pay:
8200 ft
Layer Pressure:
3600 psig
Under Balance Pressure:
100 psi
Overburden Pressure Gradient:
1 psi/ft
Water saturation:
0.3 (fraction)
Bottom hole (reservoir) Temperature:
200 degF
Kv/Kh:
0.1 (fraction)
Downhole (reservoir) Rock type:
Sandstone
Gun System:
2007 Predator Baker with 6 spf and 60 degrees phasing
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For the Relative Permeability data entry,select | Edit and populate the table according to the inputs below: Relative Permeabilities: Phase
Residual Saturation fraction
Oil
0.25
0.8
3
Water
0.25
0.8
3
PROSPER Manual
End point in fraction
in Corey Exponent
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Select | OK to exit the relative permeability input screen. For the selection of the gun system, select the button " Select Gun" and the following screen pops up, initially empty:
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To move forward, select the "Select Gun From Database" button and the database is displayed:
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Note that the data base has been filtered on Vendor: here Baker for illustration only. Now one can select the gun of choice, which is the 2" 2007 Predator
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Afterwards, one select | Done and | Done again to transfer the gun data into SPOT. To move forward, select the tab "LOG DATA" and enter the data required to generate the log-scale IPR parameters: Spot options - Log Data Generation
Uniaxial Compressive Strength:
8000 psig
Horizontal Permeability:
200 mD
Porosity:
0.25
Top Reservoir Measured Depth:
8000 ft
Bottom Reservoir Measured Depth:
8200 ft
Log Depth Increment:
0.5 ft
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Select | Generate and the log scale data are generated as shown below:
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The last section to describe is the completion section. To access this section, select the sheet "Completion" at the bottom of the screen: Spot options - Completion
Completion type:
Casing
Outer Diameter:
8.5 inches
Casing weight:
9 lb/ft
Material:
J-55
Top Measured Depth:
8000 ft
Bottom Measured Depth:
8200 ft
Drift Diameter*:
8 inches
Holdup Depth*:
8250 ft
Notes: The drift diameter is the inside diameter (ID) that the pipe manufacturer guarantees per specifications. Note that the nominal inside diameter is not the same as the drift diameter but is always slightly larger. The drift diameter is used by the well planner to determine what size tools or casing strings can later be run through the casing, whereas the nominal inside diameter is used for fluid volume calculations such as mud circulating times and cement slurry. The holdup depth is the depth at which a tool of a specific size can no longer pass through the well bore.
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One may need to scroll the bar at the bottom of the screen to the right to enter the drift:
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IPR Generation In order the generate an IPR, select | Calculate and the following plot is generated:
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3.1.41.5.6 Estimation of the well flow rate The response of a well bore combines fluid properties (PVT), reservoir data (IPR) and tubing response (VLP). The fluid properties are used to compute the reservoir response (IPR) and the tubing response (VLP). For a given set of boundary conditions (given reservoir pressure and well head flowing pressure), the well flow rate is the intersection between the IPR curve and the VLP curve. In order to compute this intersection point with PROSPER, simply select | Calculation | System (Ipr + Vlp) | 3 Variables as per screen-shot below:
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After selecting the system calculation, one needs to enter the well head flowing pressure as per screen-shot below:
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The top node pressure is the pressure downstream of the system. Since here there is no pipeline in this PROSPER model, the top node pressure is the well head flow pressure. Surface Equipment Correlation: This applies to any pipeline in the model. Since this model does not include any pipeline, the choice of any pipeline correlation is irrelevant. Vertical Lift Correlation: Petroleum Experts 2. Solution Node: Bottom Node Rate Method: Automatic - Linear Left-Hand Intersection: DisAllow One can proceed with | Continue | Continue and Calculate with the following results:
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One can read an oil rate of 5280 stb/d as solution rate. The corresponding BHFP reads: 2346 psig. If one selects | Plot | System Plot, the system plot (VLP + IPR plot) is displayed as follow:
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Select | Main to get back to the main PROSPER screen and save the file to update the file. 3.1.41.5.7 Comparison of different Gun Systems One very useful feature of the SPOT module is the ability to sensitize on gun systems. The sensitization can be performed from the IPR screen directly (| System | Inflow Perform | Sensitivity) or from the system calculation. In order to sensitize on gun systems from the system calculation, select | Calculation | System | 3 Variables and make the following changes:
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Top node pressure: 300 psig Total GOR: 400 scf/stb Vertical Lift Correlation: Petroleum Experts 2. Note: Water cut is not a sensitivity variable because SPOT uses relative permeability to compute the producing water cut. Select | Continue and select "SPOT Perforating Gun" as sensitivity variable:
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Select | Add | Select Gun From Database and add the gun systems of choice:
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For this tutorial, 2 guns systems were selected randomly: - 2007 Predator XP LS from Baker and - 2818 Predator XP One can now proceed with | Continue | Calculate | Plot | System Plot to generate the following system plot:
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Select | Main to return to the main PROSPER screen. 3.1.41.5.8 Inspection of SPOT results at log- scale SPOT allow the calculation and visualization of the Inflow results at log scale. The log scale results are accessible from the IPR screen as well as the system calculation screen. Detailed SPOT results from the IPR screen: In order to access and plot the detailed log-scale results from SPOT, select | System | Inflow Performance | Sensitivity:
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For this example, flowing BHP of 3000 psig will be used. To proceed, select | Continue | Continue | Calculate | OK | Sensitivity Detail and this would lead to the following screen:
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Select | Log Results | Plot and select Qocum for the x axis for instance:
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By selecting | Done, the following plot is generated:
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Select | Done and any other variable can be added to the plot. Any number of variables with the same unit can be selected and plotted together as demonstrated in the plot below:
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Detailed SPOT from the system calculation screen: The same level of details is available from the system calculation screen.
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From the system calculation screen, select | Solution Details
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Now select | Inflow Details | Log Results | Plot
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From this screen, any variable can be selected and plotted:
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If the Qw cum (cumulative water production) is selected for instance a plot similar to the one below can be inspected:
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Select | Done | Done | Main to get back to the main PROSPER screen.
3.1.42 Tutorial 41: Multi-Zones Completion using multilayer IPR File: ~/samples/PROSPER/T41_MultilayerGas.Out The main objectives of this tutorial is to show how to model commingled production from multiple zones using the multi-layer IPR model in PROSPER. 3.1.42.1Statement of the problem A single gas well penetrates 2 reservoirs at different depths. The reservoirs are separated by 1000 ft vertical distance. Given the significant distance between the zones, the pressure drop between the zones need to be accounted for. It is required to set-up a PROSPER model for the well to answer the following questions: - what is the commingled flow rate to be expected at a well head flowing pressure of 1500 psig? - what is the contribution from each zone? - Is there any cross-flow between the reservoirs?
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3.1.42.2Input Data Fluid PVT Parameter
Upper Zone
Lower Zone
Gas Gravity (Air =1):
0.6
0.7
Separator pressure (psig):
250
250
Condensate (stb/MMscf):
Gas
Ratio 3
Condensate Gravity (API):
50
10 45
Water to Gas Ratio (stb/ 5 MMscf):
10
Gas Impurities (H2S, CO2 & 0 N2):
0
Reservoir Data
Parameter
Upper Zone
Lower Zone
Layer IPR model:
Petroleum Experts
Petroleum Experts
True vertical depth (ft):
10000
11000
Reservoir pressure (psig):
3500
3600
Layer flowing radius (ft):
0.254
0.254
Layer roughness (inches):
0.001
0.001
Layer permeability (mD):
15
20
Layer Drainage (acres):
Area 300
300
Layer Dietz shape factor 31.6 (no dimension):
31.6
Layer wellbore radius (ft):
0.354
0.354
Perforation interval (ft):
50
30
Time since (days):
production 1000
Layer porosity (fraction): Layer connate saturation (fraction):
PROSPER Manual
0.25
water 0.3
1000 0.25 0.3
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Mechanical dimension):
skin
(no 5
1470
5
Non-Darcy Flow Factor (1/ Calculated Mscf/d)
Calculated
Deviation Survey Measured Depth in ft
True Vertical Depth in ft
0
0
10000
10000
Note: the well will be divided into inflow and outflow. The outflow covers the section above the the shallowest zone whereas the inflow will include both zones with the pressure drop between them. Therefore, it is sufficient to describe the well just down to the shallowest reservoir depth when using the multi-layer IPR model. Downhole Equipment
Equipment Type
Measured Depth in ft
Tubing ID inches
in Tubing Inside Roughness in inches
Xmas Tree
0
N/A
N/A
Tubing
9500
4.67
0.0006
Casing
10000
6.1
0.0006
Geothermal gradient Formation Measured Depth in ft
Formation Temperature in degF
0
60
10000
230
Overall heat transfer coefficient: 3 Btu/h/ft2/F.
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PROSPER
3.1.42.3Modelling Strategy For well producing from multiples zones, there are currently 3 Inflow models available in PROSPER: a) the MultiLayer Reservoir model b) the MultiLayer - dP Loss in WellBore and c) the Multilateral Inflow model. The MultiLayer Reservoir model is the simplest one. It does not account for pressure drop between the zones. Therefore it can only be considered for cases where the vertical distance between the zones is negligible. It can model a well penetrating up to 50 different zones. The "MultiLayer - dP Loss in WellBore" Reservoir model is the improved version of the MultiLayer Reservoir model, It accounts for pressure drop between the layers and offers a wider range of inflow models for each zone. It can model a well penetrating up to 49 different zones. The Multilateral Inflow model is the most advanced inflow model in PROSPER. It can model wells of any shape penetrating any number of layers. Flow can be annular, tubular or both. Well can have a single or multiple branches. Pressure drop and interaction between branches are accounted for. The multilateral model can be used to model "smart" wells with down hole control devices. Within the IPM suite, the multiphase network simulation tool GAP can also be used to model multiple zones completions. Using GAP, one can directly take advantage of the optimiser in GAP and the direct connection to a reservoir mode (MBAL, decline curve or numerical simulator) for time-dependent performance prediction. For this tutorial, the MultiLayer - dP Loss in WellBore will be used. We will first build a PROSPER model and then use the model to answer the following engineering questions: - what is the commingled flow rate to be expected at a well head flowing pressure of 1500 psig? - what is the contribution from each zone? - Is there any cross-flow between the reservoirs? 3.1.42.4Step by Step Procedure Launch PROSPER and select | Options | Options> Afterwards make the following changes: System options Fluid Description - Fluid:
PROSPER Manual
Dry and Wet Gas
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Select Done to complete the selection of the options. Fluid PVT Select PVT | Input Data and enter the fluid PVT as done below: Parameter
Upper Zone
Lower Zone
Gas Gravity (Air =1):
0.6
0.7
Separator pressure (psig):
250
250
Condensate (stb/MMscf):
Gas
Ratio 3
Condensate Gravity (API):
50
10 45
Water to Gas Ratio (stb/ 5 MMscf):
10
Water Salinity (ppm)
10000
100000
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Gas Impurities (H2S, CO2 & 0
0
N2):
Note that at this stage, the PVT of the first zone was entered for initialisation purposes. The fluid properties for each zone will be entered separately later in the inflow section. Select | Done to complete this section. System Equipment - Deviation Survey From the main screen, select | System | Equipment (Tubing etc) | All | Edit to enter the down hole equipment: Measured Depth in ft
True Vertical Depth in ft
0
0
10000
10000
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Note: the well will be divided into inflow and outflow. The outflow covers the section above the the shallowest zone whereas the inflow will include both zones with the pressure drop between them. Therefore, it is sufficient to describe the well just down to © 1990-2011 Petroleum Experts Limited
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the shallowest reservoir depth when using the multi-layer IPR model. Downhole Equipment
Select | Done | Cancel to enter the down hole equipment data: Equipment Type
Measured Depth in ft
Tubing ID inches
in Tubing Inside Roughness in inches
Xmas Tree
0
N/A
N/A
Tubing
9500
4.67
0.0006
Casing
10000
6.1
0.0006
Geothermal gradient Select | Done | Cancel to enter the geothermal gradient:
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Formation Measured Depth in ft
Formation Temperature in degF
0
60
1476
10000 230 Overall heat transfer coefficient: 3 Btu/h/ft2/F.
Select | Done | Done | Summary | Daw Down hole to check the well bore schematic generated with the data entered:
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Select | Main to return to the main PROSPER screen. Reservoir Data In order to enter the Inflow performance data select | System Inflow Performance and make the following changes: Reservoir Model:
MultiLayer - dP Loss in WellBore
Reservoir Temperature:
230 degF
Compaction Permeability Reduction Model:
No
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To proceed with the inflow description select | Input Data and make the following entries / selections:
Parameter
Upper Zone
Lower Zone
Layer IPR model:
Petroleum Experts
Petroleum Experts
True vertical depth (ft):
10000
11000
Reservoir pressure (psig):
3500
3600
Layer flowing radius (ft):
0.254
0.254
Layer roughness (inches):
0.001
0.001
Layer permeability (mD):
15
20
Layer Drainage (acres):
Area 300
300
Layer Dietz shape factor 31.6 (no dimension):
31.6
Layer wellbore radius (ft):
0.354
0.354
Perforation interval (ft):
50
30
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Time since (days):
production 1000
Layer porosity (fraction): Layer connate saturation (fraction): Mechanical dimension):
skin
0.25
water 0.3 (no 5
Non-Darcy Flow Factor (1/ Calculated Mscf/d)
1000 0.25 0.3 5 Calculated
A few notes about the description of the multilayer IPR model: - Given the large number of inputs, it is good practice to frequently use the "Validate button" in order to check the data missing to complete the model description. - The top (MD = 10000 ft / TVD = 10000 ft) describes the solution node of the well model. It divides the wellbore in inflow and outflow and should correspond to the deepest entry in the down hole equipment. This is the depth at which the inflow and the outflow equations are solved to yield the solution rate. PROSPER Manual
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- The static layer pressure for each zone is entered at the bottom of the zone. In the case of the upper layer, the pressure of 3500 psig corresponds to the static reservoir pressure at 10050 ft, NOT 10000 ft. - The layer flowing radius and the the layer roughness are used to compute the pressure loss between the zones whereas the well bore radius is used to compute the inflow performance relation for the layer itself. - The "Blank" layer type means that there is no influx or no perforation from the layer into the well bore. At this stage, it is good practice to generate an IPR with | Calculate and be patient as this is a more complex algorithm that the single zone Inflow models:
Please select | Main and save the file to secure all changes. In order to answer the engineering questions asked at the beginning of this tutorial, one needs to solve simultaneously the inflow and outflow equations. For this, select | Calculation | System (Ipr+Vlp) |3 Variables:
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Now enter the top node pressure of 1500 psig:
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Afterwards, select | Continue | Continue | Calculate and be patient as this may take a few minutes:
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The solution details can be accessed by selecting the button " Solution Details". Afterwards, select | Inflow Layer Details
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And this is the content of the inflow layer details screen:
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Conclusion: One can read that: the well would produce 33.5 MMscf/d of gas, a water-to-gas ratio of 7.2 stb/MMscf and a CGR of 6 stb/MMscf. The upper zone contributes to round 57% of the total production. Consequently, the bottom zone makes up the remaining 43%. There is no negative rate from any layer. Therefore there is no cross flow under the PROSPER Manual
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current conditions. This completes this example.
3.1.43 Tutorial 42: Multi-Zones Completion using multilateral IPR File: ~/samples/PROSPER/T42_MultiLateralInMultipleReservoirs.OUT The main objectives of this tutorial is to show how to model commingled production from multiple zones. 3.1.43.1Statement of the problem A single gas well penetrates 2 reservoirs at different depths. The reservoirs are separated by 1000 ft vertical distance. It is required to set-up a PROSPER model for the well to answer the following questions: - what is the commingled flow rate of the well at flowing well head pressure of 1500 psig? - what is the contribution from each zone? - Is there any cross-flow between the reservoirs? 3.1.43.2Input Data Fluid PVT Parameter
Upper Zone
Lower Zone
Gas Gravity (Air =1):
0.6
0.7
Separator pressure (psig):
250
250
Condensate (stb/MMscf):
Gas
Ratio 3
Condensate Gravity (API):
50
10 45
Water to Gas Ratio (stb/ 5 MMscf):
10
Gas Impurities (H2S, CO2 & 0 N2):
0
Reservoir Data
Parameter
Upper Zone
Lower Zone
Layer IPR model:
Petroleum Experts
Petroleum Experts
True vertical depth (ft):
10000
11000
Reservoir
Temperature 230
240 © 1990-2011 Petroleum Experts Limited
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(degF): Reservoir pressure (psig):
3500
3600
Layer flowing radius (ft):
0.254
0.254
Layer roughness (inches):
0.001
0.001
Layer permeability (mD):
15
20
Layer Drainage (acres):
Area 300
300
Vertical Permeability (mD): 1.5
2
Layer Dietz shape factor 31.6 (no dimension):
31.6
Layer wellbore radius (ft):
0.354
0.354
Reservoir Thickness (ft):
50
30
Perforation interval (ft):
50
30
Time since (days):
production 1000
Layer porosity (fraction): Layer connate saturation (fraction): Mechanical dimension):
1000
0.25
0.25
water 0.3
skin
0.3
(no 5
5
Non-Darcy Flow Factor (1/ Calculated Mscf/d)
Calculated
Deviation Survey Measured Depth in ft
True Vertical Depth in ft
0
0
10000
10000
Note: the well will be divided into inflow and outflow. The outflow covers the section above the shallowest zone whereas the inflow will include both zones with the pressure drop between them. Therefore, it is sufficient to describe the well just down to the top of the shallowest reservoir in the deviation survey when using the multi-layer IPR model. Downhole Equipment
PROSPER Manual
May, 2011
Examples Guide
Equipment Type
Measured Depth in ft
Tubing ID inches
Xmas Tree
0
N/A
N/A
Tubing
9500
4.67
0.0006
Casing
10000
6.1
0.0006
1488
in Tubing Inside Roughness in inches
Geothermal gradient Formation Measured Depth in ft
Formation Temperature in degF
0
60
10000
230
Overall heat transfer coefficient: 3 Btu/h/ft2/F.
3.1.43.3Modelling Strategy For a well producing from multiples zones, there are currently 3 Inflow models available in PROSPER: a) the MultiLayer Reservoir model b) the MultiLayer - dP Loss in WellBore and c) the Multilateral Inflow model. The MultiLayer Reservoir model is the simplest one. It does not account for pressure drop between the zones. Therefore it can only be considered for cases where the vertical distance between the zones is negligible. It can model a well penetrating up to 50 different zones. The "MultiLayer - dP Loss in WellBore" Reservoir model is the improved version of the MultiLayer Reservoir model, It accounts for pressure drop between the layers and offers a wider range of inflow models for each zone. It can model a well penetrating up to 49 different zones. The Multilateral Inflow model is the most advanced inflow model in PROSPER. It can model wells of any shape penetrating any number of layers. Flow can be annular, tubular or both. Well can have a single or multiple branches. Pressure drop and interaction between branches are accounted for. The multilateral model can be used to model "smart" wells with down hole control devices. Within the IPM suite, the multiphase network simulation tool GAP can also be used to model multiple zones completions. Using GAP, one can directly take advantage of the optimiser in GAP and the direct connection to a reservoir model (MBAL, decline curve © 1990-2011 Petroleum Experts Limited
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PROSPER
or numerical simulator) is available for time-dependent performance prediction. For this tutorial, the Multilateral Inflow model will be used. We will first build a PROSPER model and then use the model to answer the following engineering questions: - what is the commingled flow rate to be expected at a well head flowing pressure of 1500 psig? - what is the contribution from each zone? - Is there any cross-flow between the reservoirs? 3.1.43.4Step by Step Procedure Launch PROSPER and select | Options | Options> Afterwards make the following changes: System options Fluid Description - Fluid:
Dry and Wet Gas
Reservoir - Inflow Type:
MultiLateral Well
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Select Done to complete the selection of the options. Fluid PVT Select PVT | Input Data and enter the fluid PVT as done below: Parameter
Upper Zone
Gas Gravity (Air =1):
0.6
Separator pressure (psig):
250
Condensate Gas Ratio (stb/MMscf):
3
Condensate Gravity (API):
50
Water to Gas Ratio (stb/MMscf):
5
Water Salinity (ppm)
100000
Gas Impurities (H2S, CO2 & N2):
0
© 1990-2011 Petroleum Experts Limited
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Note that at this stage, the PVT of one of the zones (here first zone) was entered to initialise the model. The fluid properties for each zone will be entered separately later in the inflow section. Select | Done to complete this section. System Equipment - Deviation Survey From the main screen, select | System | Equipment (Tubing etc) | All | Edit to enter the down hole equipment: Measured Depth in ft
True Vertical Depth in ft
0
0
10000
10000
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Note: the well will be divided into inflow and outflow. The outflow covers the section above the the shallowest zone whereas the inflow will include both zones with the pressure drop between them. This entry applies to the outflow. Therefore, it is sufficient © 1990-2011 Petroleum Experts Limited
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here to describe the well just down to the shallowest reservoir depth when using the multilateral IPR model. Downhole Equipment
Select | Done | Cancel to enter the down hole equipment data: Equipment Type
Measured Depth in ft
Tubing ID inches
in Tubing Inside Roughness in inches
Xmas Tree
0
N/A
N/A
Tubing
9500
4.67
0.0006
Casing
10000
6.1
0.0006
Geothermal gradient Select | Done | Cancel to enter the geothermal gradient: PROSPER Manual
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Examples Guide
Formation Measured Depth in ft
Formation Temperature in degF
0
60
1494
10000 230 Overall heat transfer coefficient: 3 Btu/h/ft2/F.
Select | Done | Done | Summary | Daw Down hole to check the well bore schematic generated with the data entered:
© 1990-2011 Petroleum Experts Limited
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PROSPER
Select | Main and save the file to secure the entries. Multilateral Inflow Model Drawing the model To access the interface where to describe the multilateral IPR, select | System I Inflow Performance. The multilateral IPR interface consists in a Network section where we can draw the situation of the example using the short cut icons.
From left to right, the icons represent: - Tie-Point: this is the depth at which the combined IPR is computed. - Junction: this is a node from where a lateral can branch out. - Completion: this describes the details of the perforation and - Reservoir: contains the pertinent reservoir data like pressure, permeability, Dietzshape factor and so on. Select the first short cut icon starting from left, or click on the drop down menu and select "Add Tie-point" as shown in the next screen shot.
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Click anywhere in the blank screen to add a Tie point and give it the label "TiePoint". This correspond to a depth of 10000ft. The tie-point is the point at which the combined Inflow will be computed.
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Right clicking on the red square representing the item "TiePoint" allows the user to change its label or delete it. The next short cut icon (Going from left to right) is the Add Junction. Select Add Junction and click somewhere else in the screen to add the junction, label it "Junction".
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Then select the Add Completion next to the "Add Junction" and click in the screen to add a completion, label it "Upper Completion". For the second zone, add a second completion and label it "Lower Completion". Then select Add Reservoir from the drop down menu and click on the screen to add a Reservoir icon.Label it "Upper Zone" Then select Add Reservoir again from the drop down menu and click on the screen to add a Reservoir icon.Label it "Lower Zone" One would have an schematic similar to the next screen shot:
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Now select | Add link and connect the equipment from the tie-point to the reservoirs as done be low
TiePoint Description PROSPER Manual
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In order to describe the tiepoint, double-click on the item TiePoint and make the following entries:
One may use the navigator on the right hand side to describe the other components of the multilateral. Tubing "T1" Description After linking the tie-point to the junction, a tubing "T1" is created. In this example, this will be a zero dimension tubing. For this, double click on the tubing "T1" and make the following changes: Tubing "T1" - Select Model
© 1990-2011 Petroleum Experts Limited
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Tubing "T1" - Input Data / Deviation Survey Measured Depth
True Vertical Depth
Azimuth
10000
10000
0
10000
10000
0
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Select the tab "Equipment" at the bottom of the screen to describe the down hole equipment pertaining to this item. Tubing "T1" - Input Data / Equipment
Tubing Type
Measured Depth
Casing Diameter
Inside Casing inside roughness
-
ft
inches
inches
Casing
10000
6.1
0.0006
© 1990-2011 Petroleum Experts Limited
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PROSPER
Select | Done and then double-click on the junction to describe it as shown below: Junction Description
Here the data are passed directly from the previous node. Select | Done and then PROSPER Manual
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double-click on the "Upper Completion" to describe it. Completion "Upper Completion" - Select Model Horizontal Flow Model - irrelevant in this Dukler Flanningan example: Vertical Flow mdel:
Petroleum Experts 2
Choke model:
ELF
Flow Type:
Tubing Flow
Use Threshold Angle:
No
Angle Greater Than (From Vertical):
45 degrees
WellBore Radius:
0.354 ft
Dietz Shape Factor:
31.6
Note that it is possible to model annular flow as well. For this, simply select Annular Flow as flow type. Completion "Upper Completion" - Deviation
Measured Depth
True Vertical Depth
Azimuth © 1990-2011 Petroleum Experts Limited
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10000
10000
0
10050
10050
0
Now select the Equipment tab at the bottom of the screen to continue the description of this item. Completion "Upper Completion" - Input Data / Equipment
Tubing Type
Measured Depth
Casing Diameter
-
ft
inches
inches
Casing
10050
6.1
0.001
PROSPER Manual
Inside Casing inside roughness
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Note that a higher roughness is used the perforation interval. Select the "Perforation details" tab at the bottom of the screen to continue the description of this item. Perforatio n Interval MD start (ft)
Perforatio n Interval MD end (ft)
Perforatio n Interval TVD start (ft)
Perforatio Skin n Interval Model TVD end Choice (ft)
NonDarcy Entry Method
Local Skin
10000
10050
10000
10050
By Hand
5
By Hand
© 1990-2011 Petroleum Experts Limited
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Note that the "Non-Darcy Entry method" was set to "Calculate". Therefore, the " Calculate" button needs to be selected for further data entry that would allow the calculation of the Non-Darcy Flow Factor. Reservoir Permeability:
15 mD
WellBore Radius:
0.354 ft
Production Interval:
50 ft
Select | Done and proceed with the description of the lower completion. Double-click on the "Lower Completion" and make the following changes: Completion "Lower Completion" - Select Model PROSPER Manual
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Horizontal Flow Model - irrelevant in this Dukler Flanningan example: Vertical Flow mdel:
Petroleum Experts 2
Choke model:
ELF
Flow Type:
Tubing Flow
Use Threshold Angle:
No
Angle Greater Than (From Vertical):
45 degrees
WellBore Radius:
0.354 ft
Dietz Shape Factor:
31.6
Select | Input Data in the top right corner of the screen to proceed with the deviation survey:
Measured Depth
True vertical Depth
Azimuth
11030
11030
0
© 1990-2011 Petroleum Experts Limited
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PROSPER
Select the tab "Equipment" to proceed: Completion "Upper Completion" - Input Data / Equipment Tubing Type
Measured Depth
Casing Diameter
-
ft
inches
inches
Casing
11000
6.1
0.0006
Casing
11030
6.1
0.001
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Inside Casing inside roughness
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Select the "Perforation details" tab at the bottom of the screen to continue the description of this item. Note that a different roughness was used for the perforation interval.
Perforatio n Interval MD start (ft)
Perforatio n Interval MD end (ft)
Perforatio n Interval TVD start (ft)
Perforatio Skin n Interval Model TVD end Choice (ft)
NonDarcy Entry Method
Local Skin
11000
11030
11000
11030
By Hand
5
By Hand
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Select the | Calculate button to enter the reservoir permeability:
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Select | Done and continue the model set-up with the description of the upper zone. For this, double-click on the item "Upper Zone" and make the following entries: Reservoir "Upper Zone" - Select model Parameter
Upper Zone
Layer IPR model:
Petroleum Experts
Reservoir Temperature (degF):
230
Reservoir pressure (psig):
3500
Condensate Gravity (API):
50
Gas Gravity:
0.6
Water salinity (ppm):
100 000
Water Gas Ratio (stb/MMscf):
5
Condensate Gas Ratio (stb/MMscf):
3
Reservoir "Upper Zone" - Input Data
Reservoir Permeability (mD):
15
Reservoir Thickness (ft):
50
Drainage Area (acres):
300 © 1990-2011 Petroleum Experts Limited
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Reservoir top depth (ft):
10000
Vertical Permeability (mD):
1.5
Reservoir Porosity (fraction):
0.25
Connate Water Saturation (fraction):
0.3
Select | Done and continue the model set-up with the description of the lower zone. For this, double-click on the item "Lower Zone" and make the following entries:
Parameter
Upper Zone
Layer IPR model:
Petroleum Experts
Reservoir Temperature (degF):
240
Reservoir pressure (psig):
3600
Condensate Gravity (API):
45
Gas Gravity:
0.7
Water salinity (ppm):
100 000
Water Gas Ratio (stb/MMscf):
10
Condensate Gas Ratio (stb/MMscf):
10
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Select Input Data to proceed: Reservoir "Lower Zone" - Input Data
Reservoir Permeability (mD):
20
Reservoir Thickness (ft):
30
Drainage Area (acres):
300
Reservoir top depth (ft):
11000
Vertical Permeability (mD):
2
Reservoir Porosity (fraction):
0.25
Connate Water Saturation (fraction):
0.3
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Select | Done and then | Visualise | Front to check the schematic of the down hole network:
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Generating the composite IPR Select Analyse | Calculate
Afterwards, make the following selections:
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Afterwards, select | Calculate and be patient as this might take a few seconds: The following inflow curves are generated:
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Select | Main | Done | Finish to perform the system calculation. For this select | Calculation | System (Vlp+Ipr) | 3 Variables:
Select | Continue | Continue | Calculate and here are the solution details:
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The details of the solution point can be accessed with | Solution Details | Inflow Layer Details:
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Results: - The well produces 38 Mmscf/d. - The upper zone produce a little roughly 22 MMscf/d whereas the lower zone produce 16 MMscf/d. - There is no cross-flow under the current conditions. This completes this tutorial.
3.1.44 Tutorial 43: Jet Pump Design File: ~/samples/PROSPER/T43_JetPump.OUT The main objectives of this tutorial is to show how to model commingled production from multiple zones.
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3.1.44.1Statement Of the Problem It is intended to install a jet pump in a low productivity well. 3.1.44.2Input Data Fluid PVT Parameter
Value
Solution GOR:
100 scf/stb
Oil Gravity:
20 API
Gas gravity (Air =1):
0.7
Water Salinity:
100 000 ppm
Down hole PVT data Parameter Bubble point temperature:
Value pressure
at
reservoir 820 psig
Reservoir temperature:
150 degF
Gas Oil Ratio at bubble point pressure:
100 scf/stb
Oil FVF at bubble point pressure:
1.08 rb/stb
Oil Viscosity at bubble point pressure:
11.1 cp
Reservoir Data
Parameter
Value
Reservoir IPR model:
PI entry
Average Reservoir Pressure:
1800 psig
Reservoir Temperature :
150 degF
Water Cut:
20%
Total Produced GOR:
100 scf/stb
Productivity Index (liquid):
0.5 stb/d/psi
Deviation Survey
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May, 2011
Examples Guide
Measured Depth in ft
True Vertical Depth in ft
0
0
4100
4100
1522
Note: the deepest entry in the down hole equipment represents the datum depth for the well. This is the depth at which the average reservoir pressure refers to. Down hole Equipment
Equipment Measured Type Depth in ft
Inner Outer Diameter Roughnesses Diameter in in inches inches inches
Xmas Tree
0
N/A
N/A
N/A
Tubing
4000
2.441
2.875
0.0006
Casing
4100
6.36
N/A
0.0006
in
Geothermal gradient Formation Measured Depth in ft
Formation Temperature in degF
0
60
4100
150
Overall heat transfer coefficient: 8 Btu/h/ft2/F. Jet Pump Design Parameters Parameter
Value
Well Flow type:
Tubing Injection - Annular Production
Pump measured depth:
4000 ft
Maximum Pump Outer Diameter:
6 inches
Design Liquid Rate:
500 stb/d
Water Cut:
20%
Total GOR:
100 scf/stb
Well Head Pressure ( = Top Node 100 psig Pressure): © 1990-2011 Petroleum Experts Limited
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Surface Injection Pressure:
1500 psig
Nozzle Loss Coefficient:
0.15
Suction Loss Coefficient:
0
Throat Loss Coefficient:
0
Diffuser Loss Coefficient:
0
Tubing Correlation:
Petroleum Experts 2
3.1.44.3Jet Pump Design Strategy The strategy to design a jet pump can be broken down in 2 phases: - phase 1: build the PROSPER model and validate it against well test data if possible - phase 2: design the jet pump - phase 3: run sensitivity to predict the performance of the pump under expected conditions. 3.1.44.4Step by Step Procedure to design a jet pump Launch PROSPER and select | Options | Options> Afterwards make the following changes: System options Fluid Description - Fluid:
Oil and Water
Method:
Black Oil
Artificial Lift Method:
Jet Pump
Artificial Lift Type:
Tubing Injection Production
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Select Done to complete the selection of the options. Afterwards, select | PVT | Input Data and make the following changes: Fluid PVT Parameter
Value
Solution GOR:
100 scf/stb
Oil Gravity:
20 API
Gas gravity (Air =1):
0.7
Water Salinity:
100 000 ppm
Power Fluid:
Water
Water Salinity:
10 000 ppm
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For the PVT matching, select | Match Data and enter the relevant data as shown below: Down hole PVT data Parameter Bubble point temperature:
Value pressure
at
reservoir 820 psig
Reservoir temperature:
150 degF
Gas Oil Ratio at bubble point pressure:
100 scf/stb
Oil FVF at bubble point pressure:
1.08 rb/stb
Oil Viscosity at bubble point pressure:
11.1 cp
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For the regression, select | Done | Regression | Match All | OK | Parameters
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After reviewing the results of the regression, the combination Lasater / Petrosky will be used for this crude. For this, select | Done | Done and then select | Lasater & Petrosky as calibrated black oil correlations:
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Select | Done to complete this section. For the description of the deviation survey, select | System | Equipment | All | Edit and enter the deviation survey as shown below: Deviation Survey Measured Depth in ft
True Vertical Depth in ft
0
0
4100
4100
Note: the deepest entry in the down hole equipment represents the datum depth for the well. This is the depth at which the average reservoir pressure refers to.
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Select | Done to proceed with the description of the surface equipment. Once on the surface equipment screen, select | Cancel to skip this particular screen:
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Select | Done to proceed with the description of the down hole equipment Down hole Equipment
Equipment Measured Type Depth in ft
Inner Outer Diameter Roughnesses Diameter in in inches inches inches
Xmas Tree
0
N/A
N/A
N/A
Tubing
4000
2.441
2.875
0.0006
Casing
4100
6.36
N/A
0.0006
in
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Select | Done to proceed with the geothermal gradient and the overall heat transfer coefficient ( 8 Btu/h/ft2/F according to the input data provided) Geothermal gradient Formation Measured Depth in ft
Formation Temperature in degF
0
60
4100
150
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Select | Done | Done to complete the description of the well bore. Select | Done to return to the main screen of PROSPER. Jet Pump Design The following data will be entered in the jet pump design section: Parameter Value Well Flow type:
Tubing Injection - Annular Production
Pump measured depth:
4000 ft
Maximum Pump Outer Diameter:
6 inches
Design Liquid Rate:
500 stb/d
Water Cut:
20%
Total GOR:
100 scf/stb
Well Head Pressure ( = Top Pressure):
Node 100 psig
Surface Injection Rate:
1000 stb/d
Surface Injection Pressure:
1500 psig
Nozzle Loss Coefficient:
0.15
Suction Loss Coefficient:
0
Throat Loss Coefficient:
0
Diffuser Loss Coefficient:
0
Tubing Correlation:
Petroleum Experts 2
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To access the jet pump design section, from the main menu select: Design | Jet Pump, and enter the design data:
Select Calculate | Calculate | Done | Design to complete the design calculations and to enter the jet pump design section where different pumps can be selected from the artificial lift database to match to the actual design criteria:
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A sensitivity on jet pump injection pressure will now be done on well performance using the System 3-variables calculation:
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Enter the following sensitivity data:
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Select Continue | Calculate to perform the system sensitivity calculation and | Plot | to graphically view the results:
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For the given nozzle and sensitivity parameters, PROSPER will identify if pump cavitation will be an issue. In the above plot, one can observe that the higher injection pressures cause pump cavitation issues that are identified by the 'C' character on the pump discharge pressure curve. Select Main to return to the main screen of PROSPER.
3.1.45 Tutorial 44: Black oil Condensate Model Validation in PROSPER Condensate black oil models in PROSPER should never be matched using the previously described matching method for oils. This is because the black oil model for condensate in PROSPER uses a mathematical model and matching could throw the model out of bounds. Black oil modeling is a technique that works back from values of density and GOR measured at known surface conditions to predict properties at other points in the system and the technique is fast and accurate when applicable. The black oil PROSPER Manual
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condensate model is preferential to use as the computational time is significantly faster than using an EOS PVT approach. The matched EOS can be used to validate the black oil condensate model. The use of Volume Shift as an EOS match parameter will inevitably cause mass balance errors in the EOS if used for multiple temperature and pressures (like a pressure gradient calculation) and will adversely impact the results in PROSPER. File: ~/samples/PROSPER/T44_CONVALID.out The main objectives of this example are to show: · How to use a gradient calculation to compare pressure loss using different PVT methods · How to compare a PROSPER matched EOS gradient traverse calculation result to validate using the black oil gas condensate model Begin by opening the above PROSPER file and from the main menu select PVT | Input Data to access the PVT section or double click in the PVT window section of the main PROSPER interface.
A matched EOS can be passed to PROSPER via the Import…PRP button, from PVTP for example. PROSPER will use the EOS data to generate condensate black oil model data.
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Select Generate to activate the EOS Calculation Range dialogue:
The temperature corresponds to the reservoir temperature and the pressure values range from initial reservoir to depleted reservoir conditions. Select Calculate | Calculate to generate the black oil properties:
The saturation pressure shown in the figure above is the dew point pressure for the fluid which is required for the black oil model. Select OK | OK | Properties to generate the black oil fluid properties from the EOS PROSPER Manual
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flashed through the separator stages down to standard conditions. At this point we have all the properties to build a black oil fluid model:
Prior to using the black oil condensate model is it important to see how the PVT using the EOS model impacts pressure losses in the tubing. A gradient calculation will be done so solution points can be used from the EOS gradient calculation to review the applicability of the black oil model pressure loss predictions. From the main PROSPER menu select Calculation | Gradient Traverse and input the values as shown below.
No sensitivity variables will be used in the calculation and the Petroleum Experts 4 mechanistic model will be used. Select Continue | Continue | Calculate Record a fewcalculated measured depth vs. pressure values from the gradient traverse calculated tabular data:
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Enter them in the gradient traverse plot Test Data section (figure below) found on the gradient plot main menu bar
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The gradient traverse plot will now look like the following:
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From the Options menu select the black oil fluid model options then enter the previously calculated black oil data in the PVT section. Repeat the gradient calculation and plot the data to see if the EOS test points are still valid using the gas condensate black oil model:
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Zooming in to investigate the off-set gradient point shows that the error is approximately 20 psig (0.5 % difference) indicating that for this case the black-oil condensate model is valid with the EOS gradient predictions.
© 1990-2011 Petroleum Experts Limited
