PIPESIM Training Course

PIPESIM Training Course

June 2003

2

PIPESIM Training Manual

Copyright notice © June, 2003, Schlumberger. All Rights Reserved. No part of this manual may be reproduced, stored in a retrieval system, or translated in any form or by any means, electronic or mechanical, including photocopying and recording, without the prior written permission of Schlumberger Information Solutions, 5599 San Felipe, Suite 1700, Houston, TX 770562722.

Disclaimer Use of this product is governed by the License Agreement. Schlumberger makes no warranties, expressed, implied or statutory, with respect to the product described herein and disclaims without limitation any warranties of merchantability or fitness for a particular purpose. Schlumberger reserves the right to revise the information in this manual at any time without notice.

Trademark Information PIPESIM, GOAL, NODAL Analysis, OFM, HoSim and ECLIPSE are trademarks of Schlumberger. All other products and product names are trademarks or registered trademarks of their respective companies or organizations.

Schlumberger


PART 1: SINGLE BRANCH TUTORIALS Single Branch Tutorial 1 - Single Phase Pipeline

3

5 6

Single Branch Tutorial 2 – Multiphase Pipeline

26

Single Branch Tutorial 3 - Oil Well Performance

33

Single Branch Tutorial 4 – Black Oil Calibration and Performance Forecasting

46

PART 2: SINGLE BRANCH CASE STUDIES

64

Case Study 1 - Oil Well/ Black Oil Fluid

65

Case Study 2 - Well Performance Modelling - Nodal Analysis

73

Case Study 3 - Gas well Performance using a Compositional Fluid Model

77

Case Study 4 – ESP Selection / Design

86

Case Study 5 – Pipeline and Facilities (Compositional Fluid model)

89

Case Study 6 – Gas Lift Design, New Mandrel spacing:

95

Case Study 7 – Gas Lift Design, Current Mandrel spacing:

98

PART 3: NETWORK MODELING TUTORIALS

99

Network Tutorial 1: Looped Gathering Network

100

Network Tutorial 2: Gas Transmission Network

108

Network Tutorial 3: Water Injection System

112

PART 4 – FPT TUTORIALS

116

FPT Tutorial 1: Compositional Tank & Look Up Tables

117

FPT Tutorial 2: Black Oil Tank.

145

FPT Tutorial 3: Look Up Tables

157

FPT Tutorial 4: Daily Contract Quotas (DCQ)

163

PART 5 – SINGLE BRANCH CASE STUDIES – WORKED ANSWERS

174

Worked Answers: Case Study 1 – Oil Well Design

175

Worked Answers: Case Study 2 – Well Performance Analysis – Nodal Analysis

194

Schlumberger

4


Worked Answers: Case Study 3 – Gas Well Performance

203

Worked Answers: Case Study 4 – ESP Selection / Design

220

Worked Answers: Case Study 5 – Pipeline and Facilities

222

Worked Answers: Case Study 6 – Gas Lift Design – New Mandrel Spacing

228

Worked Answers: Case Study 7 – Gas Lift Design – Current Mandrel Spacing

230

Schlumberger


Part 1: Single Branch Tutorials

Schlumberger

5

6


Single Branch Tutorial 1 - Single Phase Pipeline The purpose of this tutorial is to familiarize the user with the PIPESIM Single Branch interface by building and running simple examples. The user will construct a simple pipeline model then calculate the pressure drop along a horizontal pipeline for a given inlet pressure and Flowrate. The user will then run some sensitivity studies on the model. Each example will follow the standard workflow for single branch modelling: 1) 2) 3) 4) 5)

Build the Physical Model Create a Fluid Model Choose Flow Correlations Perform Operations View and Analyze Results

Exercise 1: Water Pipeline Getting Started: Launch PIPESIM from the Start menu (Start -> Program Files -> Schlumberger -> PIPESIM) 1) Choose “New Single Branch Model” from the startup screen

2) From the Setup|Units menu, select SI Units

Schlumberger


7

Step 1: Define the physical components of the model:

The PIPESIM single branch model toolbox is shown below:

Select the source button

Select the End Node button

and place it in the window by clicking on the single branch window:

and place it in the window:

and link Source_1 to the End Node S1 by clicking and dragging Select the Flowline button from Source_1 to the End Node S1:

Note that the red outlines on Source_1 and Flowline_1 indicate that essential input data is missing.

Schlumberger

8

PIPESIM Training Manual Double Click on Source_1 and the source input data user form will appear. Fill the form as shown below.

Click on

to exit the user form.

Double Click on Flowline_1 and the source input data user form will appear. Fill the form as shown below:

Click on the Heat transfer tab and fill the form as shown below (adiabatic process):

Schlumberger


Click on


Step 2: Define the fluid model (water): In the Setup menu select Black Oil; the Black Oil user form will appear.

Schlumberger

9

10


Fill in the Black Oil user form as shown below:

Go to the File Menu and save the Model as CaseStudy1_WaterPipe.bps.

Step 3: Select Flow Correlations: From the Setup menu, Select Flow Correlations and ensure that the “Moody” single phase flow correlation is selected

Schlumberger


Step 3: Define the operation: In the Operations menu select the Operation Pressure/Temperature

Fill in the Pressure/Temperature Profile… User form as shown below:

Schlumberger

11

12


Step 4: Run the Model: Run the model by clicking on in the user form. The pressure calculation will be done using the Moody correlation (Default single phase correlation)

Step 5: Observe the PSPlot output: The following pressure profile should be visible by clicking on screen.

It can be seen that the outlet pressure is 58 bars.

Schlumberger

at the bottom of the


13

Click on the Data tab to display a tabular output of the Pressure/Temperature Profile

To copy this data into Excel, highlight the cells of interest, hit Ctrl+C, then select a cell in Excel and hit Ctrl+V.

Step 6: Observe the Summary File ( .sum): In the Reports menu select the Summary File option:

The following output can be observed: The Liquid Hold-up value displayed 353.4 m3 is the liquid hold up for the entire pipe.

Step 7: Observe the Output file (.out): In the Reports menu select the Output File option. The Output File is divided by default in 5 sections: 1. The INPUT DATA ECHO. (Input data and Input units summary) 2. The Fluid Property Data. (Input data of the fluid model) 3. The Profile & Flow Correlations. (Profile and selected correlations summary) 4. The Primary Output. 5. The Auxiliary Output.

Schlumberger

14


The Primary output is shown below.

It is divided into 16 sections: 1. The node number: node at which all the measures on the row have been recorded. (The nodes have by default been spaced with a 1 km interval) 2. The Horizontal Distance. (This is different from the Measured distance along the Flowline) 3. The Elevation. (Elevation from the horizontal). 4. The Horizontal Angle 5. The Vertical Angle 6. The Pressure 7. The Temperature 8. The mean mixture velocity 9. The elevational Pressure drop. 10. The Frictional Pressure drop. 11. The Actual Liquid Flow rate at the P,T conditions of the node. 12. The Actual Fre gas rate at the P,T conditions of the node. 13. The Actual Liquid density at the P,T conditions of the node. 14. The Actual Free gas density at the P,T conditions of the node. 15. The Slug Number. 16. The Flow Pattern. It can be seen that as the Pressure decreases the Liquid density decreases therefore the Flowrate has to increase to maintain the mass flow rate constant. The auxiliary output is shown below:

Schlumberger


It is also divided into 16 sections: 1. The node Number. 2. The Horizontal Distance. 3. The vertical Elevation. 4. The Pipe ID 5. The Superficial Liquid Velocity 6. The Superficial Gas velocity 7. The liquid mass flow rate. 8. The gas Mass flow rate. 9. The liquid viscosity. 10. The Gas viscosity. 11. The Reynolds Number. 12. The No-slip liquid hold-up. 13. The Liquid hold-up. 14. The Enthalpy 15. The number of Pressure iteration 16. The number of Temperature iteration. The values of the Reynolds number indicate that the flow regime is turbulent. The viscosity decreases as the pressure decreases.

Schlumberger

15

16


Exercise 2: Water Pipeline Sensitivity Study Continuing with the previous example, we will now explore how our model responds to different inlet temperatures.

Step 1: Modify the Pressure/Temperature Profile operation user form In the Operations menu select the Operation Pressure/Temperature Profile. Select Source_1 as the Component and Temperature as the Variable. In the Pressure/Temperature Profile user form press on the appears and must be filled as follows:

button, an input form

Click on the Apply button. The filled user form is shown below:

Step 2: Run the Model: Run the model by clicking on in the user form. The pressure calculation will be done using the Moody correlation (Default single phase correlation)

Step 3: Observe the PSPlot output: The following pressure profile should be visible by clicking on screen.

Schlumberger



17

It can be seen that the highest inlet temperature generates the lowest pressure drop. This is because as the temperature increases, the viscosity decreases, therefore the Reynolds number increases, the corresponding friction factor decreases and the frictional pressure gradient is lower. In the case of water the effect of the temperature on the density are negligible. Select the Data tab in the PS plot to observe all the data for each temperature in a tabular format.

Schlumberger

18


Step 4: Observe the output file (.out): In the Reports menu select the Output File option. The Output file contains by default the information for the first case only. (T = 10 deg C). In the Setup Menu, select the Define Output option as shown below:

In the Define Output user form set the No of cases to print to 7.

Schlumberger


19

Re-run the operation, open the output report and you will see the results of the seven sensitivity cases. Return to the Define Output user form. Check the Segment Data in Primary Output option and re-run the operation. Open the Output file and observe that additional segments have been inserted on each side of the nodes (placed by default 30 cm each side of each node).

Pipesim performs the pressure drop calculation for each of those additional segments by default in order to obtain precise averaged values of properties such as liquid hold-up or velocities at the main nodes

Schlumberger

20


Exercise 3: Gas Pipeline sensitivity Study Without changing any of the physical components of our previous example, we will now model single phase gas through our flowline.

Step 1: Redefine the Fluid Model: From Setup|Black Oil, modify the user form as shown below (100 % gas):

Step 2: Modify the Pressure/Temperature Profile Operation Modify the Pressure/Temperature Profile user form as shown below:

Schlumberger


21

Step 3: Run the model Run the model by clicking on

in the user form

The pressure calculation will be done using the Moody correlation (Default single phase correlation)

Step 4: Observe the Output Plot The following pressure profile should be visible by clicking on screen.

Schlumberger


22


It can be seen that the highest inlet temperatures generate the highest pressure drops. This is because as the temperature increases the density decreases therefore the Reynolds number decreases. Correspondingly, the friction factor increases and thus the frictional pressure gradient is higher. In the case of gas the effect of the temperature on the viscosity are negligible. In PS-Plot click on the “Series” menu:

Schlumberger


23

Change the Y axis from pressure to temperature and press on OK the following temperature profile will be seen.

Schlumberger

24


The temperature decrease along the pipeline is due to the Joule -Thompson effect.

Exercise 4: Calculate the gas Flowrate for a given pressure drop In the previous exercises, we calculated the Outlet Pressure given a known Inlet Pressure and Flowrate. We will now specify known Inlet and Outlet Pressures and calculate the corresponding gas flowrate.

Step 1: Modify the Pressure/Temperature profile user form Modify the Pressure/Temperature user form as shown below in order to calculate the standard gas flow rate for a given pressure drop.

Step 2: Run the Operation Run the model by clicking on

in the user form.

The pressure calculation will be done using the Moody correlation (Default single phase correlation)

Step 3: Observe the PSPlot output The Gas Flowrate corresponding to the specified pressure drop is shown in the legend beneath the profile plot

Schlumberger


25

Step 4: Observe the output files (.out): The iteration routine for this operation can be seen in the output file as shown below.

Save your file as exer4.bps and File|Close.

Schlumberger

26


Single Branch Tutorial 2 – Multiphase Pipeline The Previous examples explored single phase flow of water and gas through a pipeline. We will now create a new model and explore multiphase flow through a pipeline, following the same general workflow as before: 1) 2) 3) 4) 5)


Getting Started: 1) Select File|New|Pipeline and Facilities 2) From Setup|Units, set to SI

Step 1: Build the Physical model: Using the toolbar, contruct the model shown below:

Source_1 Data:

Schlumberger

PIPESIM Training Manual Flowline Data: (Keep all default heat transfer options)

Report tool options (same for both Report Tools)

Schlumberger

27

28


Step 2: Define the Black oil fluid model

Step 3: Choose Flow Correlations: From the Setup| Flow Correlations menu, Select the following Flow Correlations:

Schlumberger


29

Step 4: Define and Run a Pressure/Temperature profile operation From the Operations| Pressure Temperature Profile menu, enter the following:

Schlumberger

30


As the Inlet Pressure text box is left empty the value will be taken from the Source_1 user form.

Step 5: Run the model Run the model by clicking on

in the user form.

The pressure drop will be calculated using the Moody correlation (Default single phase correlation) and the Beggs and Brill Correlation.

Step 6: Observe the output file The following display can be seen in the Primary output section of the Output file.

Schlumberger


31

The flow pattern can be seen by scrolling to the right:

It can be seen that the flow is initially single-phase liquid until the pressure falls below the bubble point upon which two-phases oil-gas flow is present. The single-phase moody correlation is used in the first part of the pipe and the Beggs and Brill correlation is used in the second part of the pipe. (The hold-up for each of the segment can be seen in the auxiliary output.) The number 1.8 is the erosional velocity ratioand is only displayed when higher than 1. The spot reports output is shown below:

Schlumberger

32


Schlumberger


33

Single Branch Tutorial 3 - Oil Well Performance In this tutorial we will model well performance, following the same general workflow as before: 1) 2) 3) 4) 5)


Getting Started: 1) Select File|New| Well Performance Analysis 2) From Setup|Units, set to English

Exercise 1: Pressure Temperature Profile Step 1: Define the physical components of the Model The PIPESIM single branch model toolbar is shown below:

Select the Vertical Completion button single branch window:

and place it in the

Select the End Node button

Schlumberger

and place it in the window:

34


Select the Tubing button and link Completion_1 to the End Node S1 by clicking and dragging from Completion_1 to the End Node S1:

Note that the red outlines on Completion_1 and Tubing_1 indicate that essential input data is missing. Double Click on Completion_1 and the source input data user form will appear. Fill the form as shown below.

Schlumberger


Click on


Double Click on Tubing_1 and the source input data user form will appear. Select Simple Model as the Preferred tubing Model as shown below:

Fill the form as shown below:

Click on


Step 2: Define the black oil model Select Setup| Black Oil

Schlumberger

35

36


Enter the fluid properties as shown below:

Go to the File Menu and save the Model as CaseStudy1_Oil Well.bps.

Step 3: Select Multiphase Flow Correlations From the Setup| Flow Correlation menu, ensure that the Beggs Brill Revised correlation is selected for both Vertical and Horizontal Flow

Schlumberger


37

Step 4: Define and Run a Pressure/Temperature Profile Operation Select Operations | Pressure Temperature Profile

Enter a liquid rate of 3000 STBD and select outlet pressure as the calculated variable. PIPESIM will automatically assume that the inlet pressure is the static reservoir pressure specified in the completion.

Schlumberger

38


Step 5: Run the Model Run the model by clicking on

in the user form.



It can be seen that the outlet pressure is 730 Psia. Click on the Data tab to display a tabular output of the Pressure-Temperature Profile

Schlumberger


39

To copy this data into Excel, highlight the cells of interest, hit Ctrl+C, then select a cell in Excel and hit Ctrl+V.

Step 7: Observe the Summary File (.sum): In the Reports menu select the Summary File option:

The following output can be observed: The Liquid Hold-up value displayed 101 m3 is the liquid content of the entire pipe (linepack).

Step 8: Observe the output file (.out): In the Reports menu select the Output File option. The Output File is divided by default in 5 sections: 1) The INPUT DATA ECHO (Input data and Input units summary) 2) The Fluid Property Data (Input data of the fluid model) 3) The Profile & Flow Correlations (Profile and selected correlations summary) 4) The Primary Output

Schlumberger

40

PIPESIM Training Manual 5) The Auxiliary Output The Primary output is shown below.

It is divided into 16 sections: 1. The node number: node at which all the measures on the row have been recorded. (The nodes have by default been spaced with a 1000 ft interval) 2. The Horizontal Distance. 3. The Elevation. (Elevation from the horizontal). 4. The Horizontal Angle 5. The Vertical Angle 6. The Pressure 7. The Temperature 8. The mean mixture velocity 9. The elevational Pressure drop. 10. The Frictional Pressure drop. 11. The Actual Liquid Flow rate at the P,T conditions of the node. 12. The Actual Free gas rate at the P,T conditions of the node. 13. The Actual Liquid density at the P,T conditions of the node. 14. The Actual Free gas density at the P,T conditions of the node. 15. The Slug Number. 16. The Flow Pattern. It can be seen that as the Pressure decreases, the liquid holdup decreases. Therefore, the liquid flowrate decreases to maintain the mass flow rate constant. Also, as the pressure decreases the gas density decreases. Therefore, the gas hold-up increases and the gas velocity has to increase to maintain a constant mass flowrate. The gas volumetric flowrate increases with decreasing pressure due to gas expansion.

Schlumberger


41

The Auxiliary Output is shown below:

It is also divided into 16 sections: 1. The node Number. 2. The Horizontal Distance. 3. The vertical Elevation. 4. The Pipe ID 5. The Superficial Liquid Velocity 6. The Superficial Gas velocity 7. The liquid mass flow rate. 8. The gas Mass flow rate. 9. The liquid viscosity. 10. The Gas viscosity. 11. The Reynolds Number. 12. The No-slip liquid hold-up. 13. The Liquid hold-up. 14. The Enthalpy 15. The number of Pressure iteration 16. The number of Temperature iteration. The values of the Reynolds number (~ 50,000) indicates turbulent flow The viscosity of the liquid increases as the pressure decreases due to gas coming out of solution. Save the model as exer4.bps

Exercise 2: Sensitivity Analysis Using the model from the previous exercise, we will now perform sensitivity analysis on the reservoir pressure. Step 1: Modify the Pressure Temperature Profile Operation user form:

Schlumberger

42

PIPESIM Training Manual From the Operations | Pressure Temperature Profile menu, select as a sensitivity VertWell_1 as the Component and Static Pressure as the Variable. Enter values shown below:

Step 2: Run the Model Run the model by clicking on

in the user form.


Schlumberger



43

The pressure drop across the reservoir is identical for all case due to the PI and flowrate being constant. For the case Pws = 1000 psia the pressure is not sufficient to lift the column of fluid to the surface. The pressure reaches zero at –4000 ft. Select the Data tab in the PS plot to observe all the data for each temperature in a tabular format.

Schlumberger

44


Step 4: Observe the output file (.out): In the Reports menu select the Output File option. The Output file contains by default the information for the first case only. (Pws = 3600 psia). In the Setup Menu, select the Define Output option as shown below:

In the Define Output user form set the No of cases to print to 4.

Schlumberger


45

Re-run the operation you will see the output of the 4 sensitivity cases displayed in the Output file. Return to the Define Output user form. Check the Segment Data in Primary Output option and re-run the operation, you will see the additional segments on each side of the nodes (placed by default 30 cm each side of each node).

Pipesim performs the pressure drop calculation for each of those additional segments by default in order to obtain precise averaged values of properties such as liquid hold-up or velocities at the main nodes

Schlumberger

46


Single Branch Tutorial 4 – Black Oil Calibration and Performance Forecasting Overview An oil reservoir has been discovered in the North Sea. A vertical well has been drilled, a test string inserted and flow characteristics measured. Fluid properties at stock tank and laboratory conditions have been obtained. Reservoir simulations have been performed to predict the change in watercut over the field life. The reservoir pressure will be maintained by water injection and the preference is to avoid the use of artificial lift methods. The engineer is asked to perform the following tasks: 1) Develop a well inflow performance model applicable throughout field life. This provides a relationship between the reservoir pressure, the flowing bottom hole pressure and flowrate through the formation. 2) Develop a blackoil fluid model to match the laboratory data. It is necessary to develop a method of predicting the fluid physical properties so that the pressure losses and heat transfer characteristics can be calculated. 3) Select a suitable tubing size for the production string. 4) Review the feasibility of using gas lift as an alternative to water injection. The engineering data available is given at the end of this case study.

Getting Started 1) Select File| New| Well Performance Analysis 2) From Setup|Units, set to English

Excercise1: Insert Completion and Develop a Well Inflow Performance Model A straight line productivity index (PI) method is considered adequate in this case because the fluid flows into the completion at a pressure considerably above the bubble point and no gas comes out of solution at this stage. This applies throughout field life and the productivity index is not expected to change. The PI will not be affected by changes to the reservoir pressure because the reservoir pressure is to be maintained by water injection. The PI will not be affected by changes to the watercut through field life because the oil and water have similar mobilities in this reservoir structure. 1. Add a vertical completion to the model. This is done by pointing and clicking on the vertical completion button at the top of the screen and then pointing and clicking in the work area. A vertical completion appears as shown below.

vertical completion button

vertical completion

2. Double click on the vertical completion in the work area to enter the following data:

Schlumberger


47

3. Press the "calculate/graph…” button and enter the drill string test data as shown below and select the "plot IPR” button. This will calculate a productivity index of 25 STB/d/psi to be used throughout the analysis work.

Schlumberger

48


TIP: Right button-drag on plot to position data points. To zoom in, left button-drag a window across the data points towards the lower right. To zoom out, left button-drag a window towards the upper-left.

1. Select “OK” and ”OK” to exit dialogs

Add Tubing 1. Add a boundary node to the model by pointing and clicking on the boundary node button at the top of the screen and then pointing and clicking in the work area:-

boundary node button 2. Click on the tubing button,

boundary node and drag from the completion to the boundary node.

Completed Model Note that the red outline indicates that essential data is missing for that component.

3. Double click on the tubing and select “simple model” as the preferred tubing model. Enter the data as shown below. Set the tubing ID in the base case model to 3.83”, this will become a sensitivity variable later.

Schlumberger


2. Select OK to exit dialog

Schlumberger

49

50


Excersise 2: Develop a Calibrated Blackoil Model No analysis work can be carried out until a blackoil fluid model has been developed. This allows all of the fluid physical properties to estimated over the range of pressures and temperatures encountered by the fluid. These physical properties are subsequently used to determine the phases present, the flow regime, the pressure losses in single and multiphase flow regions, and the heat transferred to or from the surroundings. The following table contains data from a laboratory analysis of our fluid:

Fluid Analysis: Stock Tank Oil Properties: Watercut GOR Gas SG Water SG Oil API

0% 892 scf/STB 0.83 1.02 36.83 °

Bubble Point Properties: Pressure Temperature Solution Gas

2647 psia 210 °F 892 scf/STB

Blackoil Calibration Data: OFVF (above bubble point pressure) OFVF (below bubble point pressure) Dead oil viscosities Live oil viscosity Gas viscosity Gas compressibility (Z)

1.49 @ 4,269 psia and 210 °F 1.38 @ 2,000 psia and 210 °F 0.31 cP @ 200 °F and 0.92 cP @ 60 °F 0.29 cP @ 2,000 psia and 210 °F 0.019 cP @ 2,000 psia and 210 °F 0.85@ 2,000 psia and 210 °F

Note: The bubble point calibration for sat GOR is used to normalize (calibrate) the Soln GOR correlation . By specifying a higher stock tank GOR than acalibration sat. GOR, you are effectively increasing the bubble point. (ie.a plot of flowing soln. GOR vs. pressure will intersect this calibration point, but the bubble point is no longer that with which the calibrationsat. GOR is specified). Conversely, if the stock tank GOR is less than the calibration sat. GOR, then the stock tank GOR is used (takes precendence)with the calibration GOR ignored. 1.

From the Setup | Black Oil menu to enter the stock tank oil properties and the bubble point properties as shown below:

Schlumberger


51

Note: Help on the definitions and valid ranges of these stock tank properties can be obtained by selecting the “Help” at the bottom of this dialog 2. Select the Advanced Calibration Data menu, Single Point Calibration and enter the Gas Saturation at the Bubble Point pressure and temperature as shown below:

Schlumberger

52


3. press the "Plot PVT data (Laboratory Conditions)” button. 4. On the resulting plot, use the Series menu to plot the oil formation volume factor on the y-axis. The following plot should be obtained:

Schlumberger


53

Observe that the uncalibrated curve for a temperature of 210 °F shows that the predicted OFVF is higher than the measured value both above and below the bubble point pressure. • •

At 4,269 psia the predicted value is 1.52 compared to the measured value of 1.49. At 2,000 psia the predicted value is 1.41 compared to the measured value of 1.38.

To calibrate the OFVF above the bubble point pressure, select the Advanced Calibration Data tab and enter the measured value of 1.49 @ 4,269 psia and 210 °F as shown below:

Schlumberger

54


Again, click on the “Plor PVT Data (Laboratory Conditions)” and the following plot should be obtained:

Schlumberger


55

Apply OFVF calibration below the bubble point pressure. The measured value is 1.38 @ 2,000 psia and 210 °F and replot. The following plot should be obtained:

Schlumberger

56


Schlumberger


57

Calibration of the oil viscosity requires two dead oil viscosity measurements. The uncalibrated (default) approach is to use the Beggs and Robinson correlation which gives values of 1.562 cP @ 200 °F and about 23 cP @ 60 °F. The Beggs and Robinson correlation uses the oil API gravity to predict two dead oil data points based upon data obtained from around 2,000 data points from 600 oil systems. Plot the uncalibrated oil viscosity by changing the previous plot Series. The following plot should be obtained:

In this case it can be seen that the predicted oil viscosity value at a temperature of 70 °F and 14.7 psia is about 23 cP as specified by the Beggs & Robinson correlation. This is significantly different from the measured dead oil data and would lead to errors in the prediction of pressure loss. Select the Viscosity Data tab and select User’s Data for the Dead Oil viscosity correlation. Enter the two measured values of 0.31 cP @ 200 °F and 0.92 cP @ 60 °F. The following plot should be obtained:

Schlumberger

58


It can be seen that the predicted oil viscosity value at a temperature of 60 °F and 14.7 psia is 0.92 cP, consistent with the laboratory dead oil data. Return to the Advanced Calibration Data tab and enter the live oil calibration data of 0.29 cP @ 2,000 psia and 210 °F. The following plot should be obtained:

Schlumberger


59

It can be seen that the predicted oil viscosity value at a temperature of 210 °F and 2000 psia is 0.29 cP consistent with the laboratory live oil data. Proceed to calibrate the gas viscosity and the gas compressibility using the following calibration data: Gas viscosity: Gas compressibility (Z-factor):

0.019 cP @ 2,000 psia and 210 °F 0.85 @ 2,000 psia and 210 °F

Schlumberger

60


Exercise 3: Select a Tubing Size for the Production String Find the smallest tubing size that will allow this production plan to be met on the basis that the production string will not be replaced during field life. The sizes available are 3.34”, 3.83”, and 4.28”. I.D. as described in at the end of the case study.

Production plan obtained from reservoir simulation Year 0 1 2 3 4 5 6 7 8 9 10

Watercut (%) 0 0 0 0 12 20 35 40 47 54 60

Oil Flowrate, sbbl/d 13,000 13,000 13,000 13,000 11,600 9,800 7,800 6,700 5,800 4,500 3,600

1. From the Setup/ Flow correlations menu, select “Hagedorn & Brown” as the vertical multiphase flow correlation. This correlation performs well for vertical oil wells. 2. From the Operations menu, select Systems Analysis menu and choose liquid rate as the calculated variable. The minimum pressure allowed at the wellhead (outlet pressure) is 600 psia. Enter the x-axis and sensitivity data as shown below:

3. Select Run Model, and select Stock Tank Oil as the y-axis series to give the following plot:

Schlumberger


61

It can be seen that 3.83” ID tubing is the smallest size that will satisfy all of the production plan conditions.

Exercise 4: Gas Lift Feasibility Study Review the feasibility of using gas lift as an alternative to water injection to support oil production rates in later field life. The predicted decline in reservoir pressure, without water injection, is given below:

Predicted reservoir pressure decline (without water injection) Year

Pws (psia)

0 1 2 3 4 5 6 7 8 9 10

4,269 4,190 4,113 4,020 3,950 3,893 3,840 3,800 3,762 3,730 3,700

Use the artificial lift performance operation to identify how much lift gas would be needed in Year 10 to achieve the desired oil production rate of 3,600 sbbl/d with the reduced reservoir pressure of 3,700 psia. 1. Double click on the completion, and change the static reservoir pressure to 3,700 psia.

Schlumberger

62

PIPESIM Training Manual 2. Double click on the tubing, ensure that the tubing ID is 3.83”, and add a gaslift depth of 8,000 ft. Press the properties button and enter the gas lift surface temperature of 100 °F and specific gravity of 0.6. 3. From the Operations menu, select Artificial Lift Performance menu and choose the sensitivity variable system data -> watercut with one value of 60% (representing year 10). The outlet pressure is 600 psia. Enter gas lift rates of: 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mmscfd as shown below:

4. Run the model and select Oil Rate as the y-axis series. The following plot should be obtained:

Schlumberger


63

It can be seen that it would be necessary to inject 2.0 mmscfd of lift gas at a depth of 8,000 ft in order to achieve the target oil production of 3,600 sbbl/d in Year 10.

Schlumberger

64


Part 2: Single Branch Case Studies

Schlumberger


65

Case Study 1 - Oil Well/ Black Oil Fluid Exercise 1. Well Model - System Solution Given the following basic data, construct a well model and find the flowing bottom hole pressure, flowing wellhead temperature and production rate for a given wellhead pressure. Black Oil PVT Data Stock Tank Properties Water Cut 10 % GOR 500 scf/stb Gas SG 0.8 Water SG 1.05 Oil API 36 (API) Assume default PVT correlations and no calibration data Wellbore Data Deviation Data Measured Depth (ft) True Vertical Depth (ft) 0 0 1000 1000 2500 2450 5000 4850 7500 7200 9000 8550 Geothermal Gradient Measured Depth (ft) Ambient Temp. (oF) 0 50 9000 200 Overall Heat Transfer Coefficient = 5 btu/hr/ft2/F Tubing Data Bottom MD (ft) 8600 9000

Internal Diameter (inches) 3.958 6.184

Reservoir & Inflow Data Completion Model = Well PI Select “Use Vogel Below Bubble Point” Reservoir Pressure Reservoir Temperature Productivity Index

Schlumberger

3600 psia 200 oF 8 stb/d/psi

66


Result Wellhead Pressure Production Rate ? Flowing BHP ? Flowing WHT ?

300 psia

Method : • • •

Construct Model and enter above data. Run Operations > Pressure / Temperature Profile o Enter Given Outlet Pressure (Calculate Liquid Rate). o Leave “Sensitivity Variable” empty. Inspect plot and text output to determine answers.

Schlumberger


67

Exercise 2. Well Model – Nodal Analysis Using the model from Exercise 1. Add (insert) a Nodal Analysis icon at bottom hole location.

N.A. Point

Perform a Nodal Analysis operation for a given outlet (wellhead) pressure to determine the operating point (bottom hole pressure and flowrate) and the AOFP (absolute open flow potential) of the well ?.

Result (Outlet) Wellhead Pressure Operating Point Flowrate ? Operating Point BHP ? AOFP ?

300 psia


Insert the Nodal Analysis icon at bottom hole location (between the completion and the tubing). Run Operations Nodal Analysis o Enter Given Outlet Pressure. o Leave “Inflow Sensitivity” and “Outflow Sensitivity” empty. Inspect plot to determine answers.

Schlumberger

68


Exercise 3. Well Model – PVT Calibration The following measured PVT data is available to calibrate and improve the fluid model. Use the measured data to calibrate the PVT model and re-run Exercise 1. (find the flowing bottom hole pressure, flowing wellhead temperature and production rate for a given wellhead pressure) ?. PVT Calibration Data = 1.16 @ 3000psia and 200 oF.

OFVF above bubble point

Bubble Point Properties Pressure = 2100 psia, Temperature = 200, Solution Gas = 500 scf/stb Data Measured at the bubble point. OFVF = 1.22 @ 2100 psia and 200 oF Live Oil Viscosity = 1.1 cp @ 2100 psia and 200 oF Gas viscosity = 0.029 cp @ 2100 psia and 200 oF Gas Z factor = 0.8 @ 2100 psia and 200 oF Dead Oil Viscosity Measurements Viscosity = 1.5 cp @ 200 oF and 10 cp @ 60 oF. Use the following PVT Correlations : Property Solution gas OFVF at / below bubble point Live oil viscosity Undersaturated oil viscosity Gas Z

Correlation Lasater Standing Chew & Connally Vasquez & Beggs Standing

Result Wellhead Pressure Production Rate ? Flowing BHP ? Flowing WHT ?

300 psia


Enter the calibration data above into the Black Oil fluid model Run Operations > Pressure / Temperature Profile o Enter Given Outlet Pressure (Calculate Liquid Rate). Inspect plot and text output to determine answers.

Schlumberger


69

Exercise 4. Well Model – Flow Correlation Matching The following FGS survey (flowing pressure survey) is available for the well. Use the measured data to select the most appropriate vertical flow correlation. Using the selected flow correlation, determine the flowing bottom hole pressure ?. Well test & FGS Data Wellhead pressure Wellhead temperature Liquid Production Rate GOR Water cut

300 psia 130 oF 6500 stb/d 500 scf/stb 10 %

Flowing Pressure Survey Depth MD (ft) Pressure (psia) 0 300 1500 560 2500 690 4500 1200 6500 1760 7500 2070 8500 2360

Result Wellhead Pressure Vertical Correlation ? Flowing BHP ?

300 psia


Go to Operations > Flow Correlation Matching. Enter the measured depth and pressure data. o Enter Given Outlet Pressure (Wellhead) and Liquid Rate, and select the Inlet Pressure as the calculated variable. Select Flow Correlations (eg. Beggs & Brill Revised, Duns & Ros, Hagedorn & Brown).

Note : Now change the selected model vertical flow correlation in the Setup > Flow Correlations menu.

Schlumberger

70


Exercise 5. Well Model – IPR Matching Given the correct flow correlation chosen in Exercise 4, find the correct IPR (Productivity Index) that matches the test data from Exercise 4, given the reservoir pressure is known to be 3600 psia ? What is the AOFP of the well with the new PI ? The Productivity Index is expected to be in the range from 5 to 10 stb/d/psi. Note : Make sure you have changed the selected model vertical flow correlation in the Setup > Flow Correlations menu after Exercise 4.

Result Wellhead Pressure PI ? AOFP ?

300 psia

Method A: • • • •

Go to Operations > System Analysis. Enter Outlet Pressure (calculate Liquid Rate). o For “X-axis variable”, enter PI values of 5,6,7,8,9and 10. o Leave “Sensitivity Variable 1” empty. Generate a plot of calculated liquid rate vs. PI. Identify the PI which gives match to the measured production rate.

Method B: • • • • •

Go to Operations > Nodal Analysis. Enter Outlet Pressure. o For “Inflow Sensitivity”, enter PI values of 5,6,7and 8. o Leave Outflow Sensitivity empty. Generate Nodal Analysis plot. Identify the PI which gives correct solution point. Determine AOFP from Inflow (Nodal Analysis) plot.

Note : Now change the completion PI in the well model.

Schlumberger


71

Exercise 6. Well Model – Sensitivity Analysis Given the current wellhead pressure and reservoir pressure, determine at what water cut will the well die ?. Note : Make sure you have changed the completion PI in the well model after Exercise 5.

Result Wellhead Pressure Water Cut ?

300 psia

Method A: • • • •

Go to Operations > System Analysis. Enter Outlet Pressure (calculate Liquid Rate). o For “X-axis variable”, enter water cut values of 30%, 40%, 50%, 60%, 70%. o Leave “Sensitivity Variable 1” empty. Generate a plot of calculated liquid rate vs. water cut. Identify the water cut at which the calculated production rate drops to zero.

Method B: • • • •

Go to Operations > Nodal Analysis. Enter Outlet Pressure. o Leave “Inflow Sensitivity” empty. o For “Outflow Sensitivity”, enter water cut values of 30%, 40%, 50%, 60%, 70%. Generate Nodal Analysis plot. Identify the water cut for which there is no solution point.

Schlumberger

72


Exercise 7. Well Model – System Analysis, Artificial Lift. Examine how this well responds to Gas Lift. Introduce a Gas Lift Injection point at 8000 ft MD in the tubing equipment. How does the well respond to gas lift when the water cut is at 10 % and at 60 % ?. Determine the following liquid production rates for the following gas lift rates and water cut values ?. Assume wellhead pressure = 300 psia. Injection gas SG = 0.6 Injection gas surface temperature = 100 oF.

Result Gas Lift Rate (mmscf/d)

Water cut = 10% Water cut = 60% Liq. Prod. Rate Liq. Prod. Rate (stb/d) (stb/d)

0.5 1 1.5 2

Method : • • • • •

Add a Gas Lift Injection point in the tubing description (enter a default gas lift rate of 1mmscf/d). Go to Operations > System Analysis. Enter Outlet Pressure (calculate Liquid Rate). o For “X-axis variable”, enter gas lift rates of 0, 0.2, 0.5, 1, 1.5, 2 (mmscf/d). o For “Sensitivity Variable 1” enter water cut values of 10% and 60%. Generate a plot of calculated liquid rate vs. gas lift rate for different water cuts. Inspect plot and text output to determine answers.

Schlumberger


73

Case Study 2 - Well Performance Modelling - Nodal Analysis Problem Outline : An oil well is currently producing below capacity. Options for increasing production include stimulation (acidizing and/or hydraulic fracture) and gas lift. Nodal Analysis will be performed to determine the relative benefits of these courses of action.

Exercise 1. Well Model Given the following basic data, construct a well model and perform a Nodal Analysis operation to find the flowing bottom hole pressure and production rate for the given wellhead pressure. Assume default flow correlations (Beggs & Brill Revised). Black Oil PVT Data Watercut GOR Gas SG Water SG API

40 % 500 scf/STB 0.71 1.1 26 °

Bubble Point Calibration Data: Pressure Temperature Saturated Gas

2000 psia 170 °F 500 scf/STB

Assume default PVT correlations and no calibration data. Wellbore Data Surface Temperature Kick-off MD Perf MD Perf TD Reservoir Temp Tubing ID Completion Data • Completion Type : Pseudo steady state. o Basis of IPR : Liquid. • Use Vogel correction below the bubble point. Pressure 3700 psia Temperature 170 °F Permeability 50 md Thickness 30 ft Wellbore diameter 6 in Drainage radius 2000 ft Skin (mechanical) 3 Use calculated rate dependent skin Schlumberger

60 F 2000 ft 7500 ft 7000 ft 170 °F 2.992 in

74


Method : • •

•

Construct Model and enter above data. Place Nodal Analysis icon at bottom hole. Run Operations > Nodal Analysis o Enter Given Outlet Pressure. o Leave “Max Rate” empty (PIPESIM will calculate rates upto the AOFP) o Leave “Inflow Sensitivity” and “Outflow Sensitivity” empty. Inspect plot to determine answers.

Result Wellhead Pressure Production Rate ? Flowing BHP ?

Schlumberger

250 psia


75

Exercise 2. Nodal Analysis – Sensitivity to Stimulation & Gas Lift. Investigate the increase in production through stimulation and gas lift using nodal analysis. a) Assume that the current skin of 3 can be reduced to 0 if the well is acidized and –2 if hydraulically fractured. b) Insert a gas lift injection point at 4500’ (with lift gas gravity of 0.6 and a surface gas temperature of 90F). What increase in production can be achieved by each approach?

Outlet Pressure = 250 psia. Oil Production Rates (STBD) – Beggs-Brill:

Completion base (skin = 3) acidized (skin = 0) fractured (skin = -2)

0 (base)

Gas Lift (mmscf/d) 0.5 1.0

2.0

Method : • •

• •

Add a Gas Lift Injection point at 4500. (Assume default gas lit rate = 0). Run Operations > Nodal Analysis o Enter Given Outlet Pressure. o Leave “Max Rate” empty (PIPESIM will calculate rates upto the AOFP) o For “Inflow Sensitivity”, enter skin values of 3,0,and -2. o For “Outflow Sensitivity”, enter gas lift rate values of 0,0.5,1.0and 2.0 mmscf/d. Generate Nodal Analysis plot. Inspect plot to determine answers.

Schlumberger

76


Exercise 3. Nodal Analysis – Sensitivity to Flow Correlation. While the Beggs & Brill correlation is widely used and is the default correlation for PIPESIM, it is useful to see the results when using alternative correlations. Unlike the Beggs & Brill correlation, Mukherjee & Brill accounts for effects of viscosity, which for this case may be significant because the oil is relatively heavy (26 º API). Repeat the nodal analysis using Mukherjee & Brill vertical flow correlation.

Outlet Pressure = 250 psia. Oil Production Rates (STBD)– Mukherjee & Brill:


0 (base)

Gas Lift (mmscf/d) 0.5 1.0

2.0

Method : • •

• •

Change the vertical flow correlation to Mukherjee & Brill. Run Operations > Nodal Analysis o Enter Given Outlet Pressure. o Leave “Max Rate” empty (PIPESIM will calculate rates upto the AOFP) o For “Inflow Sensitivity”, enter skin values of 3,0,and -2. o For “Outflow Sensitivity”, enter gas lift rate values of 0,0.5,1.0and 2.0 mmscf/d. Generate Nodal Analysis plot. Inspect plot to determine answers.

The discrepancy between Beggs & Brill and Mukherjee & Brill, ranges from 1-15%. However, both cases agree fairly well in terms of relative added benefit shown by sensitivity cases. Notice that in changing the flow correlation, the inflow curves remain unchanged. This is because Nodal Analysis “decouples” the system, creating two independent parts. Ultimately, project economics and future production potential based on reservoir conditions will weigh heavily in the final decision.

Schlumberger


77

Case Study 3 - Gas well Performance using a Compositional Fluid Model A gas well has been drilled. DST data is available as well as FGS data from a completed neighbouring identical well. The objective here is to construct a model of the well using the compositional editor, and then perform various PIPESIM operations on the well to determine certain characteristics.

Exercise 1: Simple Well Model The first exercise is to construct a gas well model.

Use the following data for the reservoir and completion: Reservoir Data Static Pres 4,600 psia Reservoir Temp. 280oF Gas PI 2 x 10-6 MMSCFD/d/psi2 Completion Data Mid perf TVD 11,000 ft Mid perf MD 11,000ft Ambient temp 30oF EOT MD 10,950 ft Tubing ID 3.476” Casing ID 8.681”

Fluid Model: Enter the PVT data as per the tables below. Tasks: 1. Determine the water content at saturation at reservoir conditions.

Schlumberger

78

PIPESIM Training Manual 2. Generate a phase envelope using the water saturated composition. 3. Determine the flow-rate, bottom-hole flowing pressure, bottom-hole flowing temperature and well-head temperature given a well-head pressure of 800 psia.

Method: 1. To determine the water content at saturation, enter the given data into the compositional table in the composition editor, from the Setup Menu. Add some water (ie 20 moles). Go to the “Single point flash” tab, click the PT radio button, enter the given reservoir P/T, and read the water content for the vapour fraction from the screen. Enter this value and the re-normalised hydrocarbon composition back into the compositional editor’s main screen. 2. To generate a phase envelope, click on the “Phase Envelope” button in the main compositional editor screen (where the composition was entered). Do this for the composition with the aqueous fraction. 3. • Build a simple completion using the completion icon, tubing icon and an outlet node. Enter the given gas PI and reservoir pressure and temperature in the completion inflow section, and the given tubing information in the tubing section. • Run a “Pressure/Temperature Profile” from the Operations drop-down menu using an outlet pressure of 800 psia. The flow-rate, pressures and temperatures can be found in the “Summary File”, from the Reports drop-down menu. Compositional PVT Data (no water) Composition (%) C1 C2 C3 iC4 nC4 iC5 nC5 C6 C7+

78 8 3.5 1.2 1.5 .8 .5 .5 6

Stock tank Properties C7+ BP 214oF + C7 MW 115 C7+ SG 0.683 Flow Correlation Select Duns & Ros vertical flow correlation Results: Pres = 4,600 psia, Tres = 280oF % H2O @ saturation Po = 800 psia QG Pwf BHT WHT

Schlumberger


79

Exercise 2: Calibrate Inflow Model The Back Pressure equation can be used to determine the IPR of a Pseudo Steady State gas well using test data. In this exercise, we will use the Back Pressure Inflow model to represent the inflow relationship. Tasks: 1. Using the below DST data, calculate the C and n parameters. 2. Determine the flow-rate, bottom-hole flowing pressure, bottom-hole flowing temperature and well-head temperature using the new inflow model. Method: 1. Double-click on the completion icon then select the Back Pressure Equation from the dropdown menu. Click on “Calculate/Graph”, then enter the test data in the dialogue box. 2. Re-run the Pressure/Temperature Profile operation as in Exercise 1 Task 3. DST data for Back Pressure Equation QGas (MMSCFD) 9.728 11.928 14.336

Pwf (psia) 3000 2500 1800

Results: Back Pressure Equation Parameter C Parameter n Po = 800 psia QG Pwf BHT WHT

Schlumberger

80


Exercise 3: Perform Nodal Analysis at bottom-hole Nodal analysis can be used to determine the optimum tubing size. The available tubing sizes have IDs of 2.992”, 3.958”, 4.892” and 6.184”. Tasks: 1. Perform nodal analysis using the available tubing sizes. 2. Plot the depth versus erosional velocity ratio from the profile plot for all tubing sizes. 3. Determine the flow-rate, bottom-hole flowing pressure, bottom-hole flowing temperature and well-head temperature for 3.958” ID tubing at an outlet pressure of 800 psia. What is the erosional velocity ratio for this tubing at the wellhead. Continue using this tubing size in all subsequent exercises. Method: 1. Use the “Nodal Analysis” option from the Operations drop-down menu. You will need to enter a Nodal Analysis icon if you have not done so already. Enter in the tubing IDs as the Outflow sensitivity. 2. Run a Pressure/Temperature profile using the tubing size as the sensitivity (remember to activate the sensitivity). From the profile plot, change the x-axis to “Erosional Velocity Ratio” by selecting the Series option from the toolbar. 3. Look in the Summary File for the flow-rate, bottom-hole flowing pressure, bottom-hole flowing temperature and well-head temperature for the 3.958” tubing. Results: Po = 800 psia QG Pwf BHT WHT Well-head, 3.958” tubing Erosional velocity ratio

Exercise 4: System Analysis System Analysis can be used to model the gas rate vs reservoir pressure for the different tubing sizes (amongst other things). Task: Generate a chart to show the variation of gas rate with the reservoir pressure for the different tubing sizes. Use a wellhead pressure of 800 psia. Use reservoir pressures of 4600, 4200, 3800, 3400 psia. Method: Select “System Analysis” from the Operations drop-down menu. Use the Reservoir Pressure as the xaxis variable and tubing ID as the sensitivity variable. Run the model and view the resultant plot.

Schlumberger


81

Exercise 5: Flow-line and Choke Add a flow-line and a choke to the model using the below data.

Flow-line Details Flow-line length (ft) 300 Flow-line ID 6 Pipe Roughness (in) 0.001 Wall thickness (in) 0.5 Ambient Temp (F) 60 Note: enter any choke size you wish as this will be overridden by the sensitivity variable

Task: Using the mechanistic choke model, determine the choke size (mechanistic choke model) that results in a manifold pressure of 710 psia (manifold is at end of flow-line) using the gas rate as calculated in Exercise 3, Task 3. Ensure that the tubing ID is 3.958”. Method: The operation “Pressure/Temperature Profiles” can be used for this task. Using choke size as the sensitivity (a good estimate would be from 1” to 3” in increments of ½”), look in the Summary File to find the choke size that gives the correct outlet pressure (710 psia). Note that the wellhead pressure will remain at 800 psia. Use a flow-rate of 15.7 MMSCFD if unable to get results for Exercise 3. Results: Po = 710 psia Choke size Continue using that choke size in model (double click on the choke and enter that choke size).

Schlumberger

82


Exercise 6: Higher liquid loading / Flow Correlation Matching In the future it is expected that there will be a higher liquid loading due to increased condensate production as the reservoir pressure declines to 4300 psia. Reactivate flowline and choke. Ensure choke bean size is 2”. Tasks: 1. Save the model under a new name, then enter the heavier composition with higher liquid fraction. Determine the water content at saturation at the lower reservoir pressure, then proceed with the following tasks and exercises. 2. Using the FGS data determine the best vertical multi-phase flow correlation for use in this well. Choose from Beggs & Brill Revised, Duns & Ros, and Hagedorn & Brown. Find the mean arithmetic and absolute differences for the chosen correlation. Continue using that correlation. Use an outlet pressure of 800 psia for this operation. 3. Using the heavier composition and chosen vertical multi-phase flow correlation, determine the new gas flow-rate, bottom hole flowing pressure and actual liquid flow at the perforations and outlet for a manifold pressure of 710 psia. Method: 1. Determine the water content at saturation for the new composition as per the same method in Exercise 1 using the compositional editor. 2. De-activate choke and flow-line for this operation (hence the outlet pressure of 800 psia will be the well-head pressure). From the Operations menu, select “Flow Correlation Matching”. Enter in the FGS data, check the correlations to be used, then click on the “Run Model” button. Look in the Output File for the mean arithmetic and absolute differences. 3. Run a Pressure/Temperature Profile Operation using an inlet pressure of 4300 psia, then look in Output File for actual liquid flows Compositional PVT Data (higher condensate fraction) Composition (%) C1 C2 C3 iC4 nC4 iC5 nC5 C6 C7+

75 6 3 1 1 1 .5 .5 12

Depth (ft) 3,000 6,000 9,000 11,000

Pressure (psia) 950 1,095 1,250 1,365

FGS Data

Producing gas rate during FGS = 13.4 MMSCFD Wellhead Pressure during FGS = 800 psia

Schlumberger


83

Results: Pres = 4,300 psia, Tres = 280oF % H2O @ saturation Po = 800 psia Best Correlation Mean arithmetic difference (%) Mean absolute difference (%) Po = 710 psia QG Pwf QL @ mid-perfs (act) QL @ outlet (act)

Exercise 7: Liquid Hold-up fraction and Flow Regime Map Tasks: 1. Determine the liquid volume fraction and hold-up fraction at the bottom of the well, at the top of the well, and at the end of the flow-line. 2. Generate a flow regime map for the end of the flow-line. Look at the flow-map and determine the flow regime at the end of the flow-line. Method: 1. Re-run the Pressure/Temperature Profile Operation as performed in Exercise 6, Task 3. Look in Auxiliary Output Page at the bottom of the Output File. 2. Add the report icon at the end of the flow-line and select Flow Map. Re-run the model. The flow regime at the end of the flow-line can be determined from both the Summary File and Output file. The flow map can be viewed at the bottom of the Output File. Results: Liquid Volume Fraction, Po = 710 psia xVL @ bottom-hole xVL @ WH xVL @ end flow-line Flow regime end FL Liquid Hold-up Fraction, Po = 710 psia xHL @ bottom-hole xHL @ WH xHL @ end flow-line Note:

xVL = liquid volume fraction xHL = liquid hold-up fraction

Schlumberger

84


Exercise 8: Pressure/Temperature path from Reservoir Tasks: 1. Plot the PT path from the reservoir to the end of the flow-line on the phase diagram. 2. Will hydrate formation be a problem? Method: 1. Select phase envelope in the report icon, run the Pressure/Temperature Profile from Exercise 7, Task 2, then change the axes on profile plot to Pressure vs Temperature. 2. From the generated plot, if the operating line crosses the hydrate formation line, hydrate formation will occur. Results: Ambient Temp = 30oF Hydrate formation?

Exercise 9: Pressure Drop due to increased condensate production The increased liquid loading is expected to cause a higher pressure drop through the production system. Tasks: 1. Calculate the well-bore pressure drop across the formation, tubing, choke and flow-line for a gas flow-rate of 13 MMSCFD Method: 1. Run a Pressure/Temperature Profile operation using a gas rate of 13 MMSCFD. Check the appropriate check-box so that it calculates the outlet pressure for the given gas rate. Results: Heavier composition ∆P Reservoir ∆P Tubing ∆P Choke ∆P Flow-line

Schlumberger


85

Exercise 10: Rigorous Flashing To reduce solving time, the calculation engine does not perform a flash at every pipe segment to determine the average fluid properties across the given segment, instead it interpolates the properties at each segment based on the results of an initial series of flashes performed prior to iterating. By selecting the Rigorous Flash option from the “Flashing” section of the Setup menu, the fluid will be flashed and the properties averaged at every pipe segment. This method is more accurate, and can occasionally cause significantly different results, particularly when operating near a phase boundary. The trade-off with using the more accurate Rigorous Flash option is the solving time, which is significantly longer. Task: Repeat Exercises 6 (Task 3) and 8 (tasks 1 and 2) using the rigorous flash option. Compare the results. Why are there any differences? Po = 710 psia QG Pwf QL @ mid-perfs (act) QL @ outlet (act) Ambient Temp = 30oF Hydrate formation?

Schlumberger

86


Case Study 4 – ESP Selection / Design This case study will demonstrate the following workflow : 1. 2. 3. 4. 5.

Analyse a well’s requirement for artificial lift. Select an appropriate ESP pump. Calculate the number of stages required for design conditions. Evaluate the variable speed performance of the pump. Evaluate the pump performance with varying well conditions.

Exercise 1. Well Model – Nodal Analysis Given the following basic data, construct a well model and perform a Nodal Analysis at bottom hole. Assume no pump in the well at this stage. Confirm that the well will not flow naturally. Black Oil PVT Data Water Cut = 90% GOR = 80 m3/m3 (449scf/stb) Oil Gravity = 876 kg/m3 (30o API) Gas Gravity = 0.984 Water SG = 1.026 Bubble Point = 152.8 bara (2216 psia) at 142.2 oC (288 oF) Formation Volume Factor = 1.33 rb/stb at bubble point. Oil Viscosity = 0.54 cp at bubble point Wellbore Data Vertical well Perforation depth 2863m (9393 ft) Flow is in : 41/2 “ (3.958” ID) tubing from surface to 2500 m 95/8 “ (8.681” ID) casing from 2500m to 2863 m * * (note the pump setting depth in the next exercise will be at 2500 m) Surface Ambient Temperature = 20 oC (68 oF) Reservoir & Inflow Data Reservoir Pressure = 250 bara (3625 psia) Reservoir Temperature = 142.2 oC (288 oF) Productivity Index = 28.5 m3/d/bar (12.4 stb/d/psi) Use nonlinear correction below bubble point Use Hagedorn & Brown Vertical Flow Correlation.

Method : • •

Construct Well Model and enter above data. Place Nodal Analysis icon at bottom hole. Run Operations > Nodal Analysis o Enter Given Outlet Pressure. o Leave “Max Rate” empty (PIPESIM will calculate rates upto the AOFP) o Leave “Inflow Sensitivity” and “Outflow Sensitivity” empty.

Schlumberger

PIPESIM Training Manual •

87

Inspect plot.

Exercise 2. Pump Selection / Design Given the design conditions below, determine the following : 1. The number of stages required using a Reda HN13000 pump. 2. The motor HP required. 3. Generate a Pump Performance Plot showing the potential operating (flowrate) range for varaible frequency between 50 to 70 Hz. 4. From the Pump Performance Plot, determine at what flowrate the pump suction pressure falls below the bubble point.

Design Conditions : Design Production Rate = 1600 sm3/d Design Wellhead (Outlet) Pressure = 8 barg Pump setting depth = 2500 m (i.e. within the 95/8“ (8.681” ID) casing Design Frequency = 60 Hz (assume no gas separator present, no viscosity correction and a head factor of 1).

Result 1). No. of stages (HN13000) ? 2). Motor HP required ? 3). Flowrate range for 50 – 70 Hz. ? 4). Flowrate for Psuction < Pbubble point ?

Method : • • • • • • • • • • •

Go to Design > ESP Design in top menu. Enter the Pump Design Data given. Click the “Select Pump” button. (This will filter the pump database for all pumps which meet the design criteria). Select Manufacturer to Reda. Highlight and select the Reda HN13000 pump. Click on the “Calculate” button in Pump Parameters section. (This will calculate the pump parameters). Read the No. of stages required. Read the motor HP required. Click on the “Pump Performance Plot” at the bottom of the Pump Parameters section. Read off the flowrate at the intersection of the Well System Curve and the 50Hz and 70 Hz pump curves. Read off the intersection of the pump suction pressure curve and the bubble point curve.

Schlumberger

88


Exercise 3. Pump performance with varying well conditions Now install the selected pump in your well model by clicking on the “Install Pump” button at the bottom of the Pump Parameters section. Determine the flowrate of the well when the water cut increases to to 95% (assuming the same number of stages and design speed).

Result Production Rate (95% wcut) ?

Method : • • • • •

Install the pump in your well model by clicking on the “Install Pump” button at the bottom of the Pump Parameters section. Go to Operations > System Analysis. Enter Outlet Pressure (i.e. select calculated variable = Liquid Rate). o For “X-axis variable”, enter watercut values of 90 and 95 % o Leave “Sensitivity Variable 1” empty. Generate a plot of calculated liquid rate vs. watercut. Read off the production rate for water cut 95%..

Schlumberger


89

Case Study 5 – Pipeline and Facilities (Compositional Fluid model) Overview Five condensate wells are to produce into a subsea manifold, through a subsea tieback and up a riser to a platform. The oil and gas are then to be separated, with the oil pumped to shore and the gas compressed to shore. The expected production rate is 14,000 STBD and the system will be designed to accommodate between 8,000 STBD (turndown case) and 16,000 STBD should the wells produce more than expected. The engineer is asked to perform the following tasks: 1) Develop a compositional model of the hydrocarbon phases 2) Size the subsea tieback line and riser 3) Screen the for severe slugging at riser base 4) Determine the pipeline insulation requirement 5) Size a slug catcher

Exercise 1: Develop the compositional PVT model based on the following data: Pure Hydrocarbon Components Component Methane Ethane Propane Isobutane Butane Isopentane Pentane Hexane Petroleum Fraction Name C7+ Aqueous Component Component Water

Moles 75 6 3 1 1 1 0.5 0.5

Boiling Point (°F) 214

Molecular Weight 115

Specific Gravity 0.683

Moles 12

Volume ratio (%bbl/bbl) 10

Method: 1) Use the menu to enter the pure components given at the end of the case study. Select the pure hydrocarbon components from the component database. Multiple selection is possible by holding down the control key. When all pure hydrocarbon components have been selected, press the "Add>>" button. 2) Select the "Petroleum Fractions" tab and characterise the petroleum fraction "C7+" by entering the petroleum fraction name, the BP, MW, and SG in row 1. Highlight the row by pressing on the row “1” button and then press the "Add to composition>>" button. 3) Return to the "Component Selection" tab and enter the number of moles for C7+. 4) Generate the hydrocarbon phase envelope by pressing the "Phase Envelope" button.

Schlumberger

90


Exercise 2: Size Subsea Tieback Determine the required ID for the subsea tieback such that the separator pressure for the maximum expected rate is no less than 400 psia. The riser must be the same ID as the tieback. In addition, ensure that the errosional velocity is not exceeded. First, build the physical model as shown below with the following data:

Schlumberger


Manifold Outlet pressure Temperature

91

1500 176

Subsea tieback Rate of undulations Horizontal Distance Elevational difference Available ID's Heat Transfer: Ambient temperature

psia ºF

0'/1000' 6 0' 9,10,11

(not hilly) miles (horizontal) "

Pipe thermal conductivity Insulation thermal conductivity Insulation thicknesses available

38 35 0.15 0.75"

ºF Btu/hr/ft/°F Btu/hr/ft/°F + 0.25" increments

Ambient fluid Ambient fluid velocity Burial depth Ground conductivity

water 1.5 -5.5 1.5

Riser (use detailed profile) Horizontal Distance Elevational difference Available ID's Heat Transfer:

0' 1600' 9,10,11

Ambient temperature @ riser base Ambient temperature @ 1200' Ambient temperature @ 800' Ambient temperature @ 400' Ambient temperature @ topsides Pipe thermal conductivity Insulation thermal conductivity Insulation thicknesses available

38 42 48 56 68 35 0.15 0.75"

Ambient fluid Ambient fluid velocity

water 1.5

ft/sec " (not burried) Btu/hr/ft/°F

(vertical pipe) " ºF ºF ºF ºF ºF Btu/hr/ft/°F Btu/hr/ft/°F + 0.25" increments ft/sec

Method: 1) Perform a System Analysis with the minimum, maximum and expected flow rates as the x-axis variable, and the available ID’s for the flowline and riser as Change in Step sensitivity variables. 2) Determine the minimum flowline ID that satisfies the separator pressure requirement for the maximum flow rate. 3) Change the y-axis to display Errosional Velocity Ratio and check to ensure that the selected flowline ID does not exceed an errosional velocity ratio of 1.0.

Schlumberger

92


Result Pipeline and Riser ID: Max. errosional velocity ratio for selected ID Min. Separator pressure for selected ID Max. separator pressure for selected ID

Exercise 3: Check for Severe Slugging Based on the ID selected above, determine the likelihood of severe slugging occurring at the riser base. Severe riser slugging is likely in a pipeline system followed by a riser under the following conditions: 1. The presence a long slightly downward inclined pipeline prior to the riser. 2. Fluid flowing in the "stratified" or "segregated" flow regime (as opposed to the usual "slug" or "intermittent" flow regime). 3. A slug number (PI-SS) of lower than 1.0. Method: 1) Configure the y-axis of the System Analysis plot to display the PI-SS number. This represents the maximum value of the PI-SS number along the flowline. 2) View the Summary Report (Reports -> Summary File), to determine the prevalent flow regime at the riser base for the different rates. Result

8000 STBD

PI-SS number at riser base Flow pattern at riser base

Schlumberger

14000 STBD

16000 STBD


93

Exercise 4: Select tieback insulation thickness Using the tieback/riser ID selected above, determine the thickness of insulation required for both the flowline and riser such that the temperature of the fluid does not come within 10ºF of the Hydrate curve for all possible flow rates. Method: 1) Start with an insulation thickness of 0.75”. Ensure that “phase envelope” is checked in the Report Tool (located upstream of separator) and perform a pressure-temperature profile with Separator (outlet) pressure as the calculated variable and with flowrates as the sensitivity variables. 2) Use the Series menu on the resulting plot to change the x-axis to Temperature. 3) Observe the production path on the phase envelope and its proximity to the Hydrate curve. 4) If required, perform successive runs while increasing the thickness by 0.25” each time until sufficient.

Result Req. Insulation thickness

Exercise 5: Size Slug Catcher Determine the required size of the slug catcher based on the largest of following criteria multiplied by a safety factor of 1.2. 1. The requirement to handle the largest slugs envisaged (chosen to be statistically the 1/1000 population slug size). 2. The requirement to handle liquid swept in front of a pig. Method: 1.) Ensure that “slugging values” and “sphere generated liquid volume” are selected in the report tool. 2.) Under Setup -> Define Output, select 3 cases to print 3.) Re-run pressure-temperature profile open output report. This report provides the full output of each sensitivity with Report Tool selections appended to the bottom of each sensitivity output. For each sensitivity, scroll down to this section and read the reported “1/1000 slug volume” and “Total Sphere Generated Liquid Volume So Far”. 8000 STBD

Result 1/1000 slug volume (ft3) Sphere generated liquid volume (ft3) Design volume for slug catcher (ft3)

Schlumberger

14000 STBD

16000 STBD

94


Notes on SGLV Calculation: When a sphere is introduced into the line, it will gather in front of itself a liquid slug made from "all the liquid that is flowing slower than the mean fluid flowrate in the pipeline at any given point". Thus the crucial value that determines Sphere Generated Liquid Volume (SGLV) is the Slip Ratio(SR), which is the average speed of the fluid divided by the speed of the liquid. If the liquid and gas move at the same speed, the slip ratio will be 1, i.e. there is 'no slip' between the phases. In this situation the sphere will not collect any liquid, so the SGLV will be zero. Normally the liquidflows slower than the gas, i.e.. the slip ratio is greater than 1, so "some" of the liquid in the pipeline will collect in front of the sphere to form the SGLV. The only way that "all" of the liquid in the pipeline will collect to form the SGLV, is if the liquid velocity is zero, i.e.. the slip ratio is infinite. This cannot happen in a steady-state reality, so the SGLV is always smaller than the total liquid holdup.

Schlumberger


95

Case Study 6 – Gas Lift Design, New Mandrel spacing: This case study will demonstrate the following workflow: 1. Analyse a well’s requirement for artificial lift. 2. Perform a Gas Lift Design for the well using the “IPO Surface Close” method.

Exercise 1. Well Model – Nodal Analysis: Given the following basic data, construct a well model and perform a Nodal Analysis at bottom hole. Assume no gas lift valves in the well at this stage. Confirm that the well will not flow naturally. Assume wellhead pressure = 110 psig. Black Oil PVT Data Water Cut = 55% GOR = 300 scf/stb Oil Gravity = 32o API Gas Gravity = 0.64 Water SG = 1.05 Flow Correlation Select Hagedorn and Brown Vertical Flow correlation. Wellbore Data Vertical well: MD (ft) TVD (ft) 0 0 7550 7550 Perforation depth 7550 MD Geothermal Survey: MD (ft) Ambient (F) Temp 0 50 7550 175

U Value (Btu/hr/ft2/F) 2 2

Flow is in: 2 7/8 “ (2.441” ID) tubing from surface to 7500 ft 7 “ (6.184” ID) casing from 7500 ft to 7550ft

Reservoir & Inflow Data Reservoir Pressure = 2800 psig Reservoir Temperature = 175 oF Productivity Index = 2.5 stb/d/psi Use Vogel below bubble point Method: •

Construct Well Model and enter above data. Place Nodal Analysis icon at bottom hole.

Schlumberger

96


•

Run Operations > Nodal Analysis o Enter Given Outlet Pressure. o Leave “Max Rate” empty (PIPESIM will calculate rates up to the AOFP) o Leave “Inflow Sensitivity” and “Outflow Sensitivity” empty. Inspect plot.

Exercise 2: Lift Gas Response Using the Lift Gas Response operation, determine the gas lift rate that will be used for the design. Use sensitivity values 0, 0.1, 0.2, 0.3, 0.5, 0.7, 1, 2, 3, 5 mmscf/d for the gas lift rate. Use sensitivity values of 150 and 250 psi for the Minimum injection gas ∆P (to investigate it’s effect on injection depth). Use an injection gas surface pressure of 1000 psig and assume an injection gas surface temperature of 80 F. Method: •

Run the Lift Gas Response operation in the Artificial lift menu, Gas lift submenu.

Exercise 3: Gas Lift Design Given the design conditions below, determine the following: 1. Determine the required Mandrel spacing to unload the well. 2. The test rack pressure of each of the unloading valves. Design Conditions: Design Control: Design Spacing: New Spacing. Design Method: IPO-Surface Close. Top Valve Location: Assume Liquid to Surface. Manufacturer: SLB (Camco) Type: IPO Size: 1’’ (Tubing size 2 7/8 < 3 ½) Series: BK-1. Min Port Diameter: None. Unloading Temperature: Default (Unloading) Production Pressure Curve: Production Pressure Model. Design Parameters: Kickoff Pressure: 1000 psig. Available Injection Pressure: 1000 psig. Unloading Prod. Pressure: 110 psig. Operating Prod. Pressure 110 psig. Target Injection Gas Flowrate: 1.25 mmscf/d. Injection gas Surface Temp: 80 F. Inj Gas Specific Gravity: 0.64. Unloading Gradient: 0.465 psi/ft. Minimum Valve Spacing: Calculated.

Schlumberger


97

Minimum Valve Inj DP: 150 psi Bracketing Options: Not selected. Safety Factors: Surface Close Pressure Drop Between Valves: 15 psi. Locating DP at Valve Location: 50 psi. Transfer Factor: 0. Place Orifice at operating valve location: Yes. Discharge Coefficient for Orifice: 0.865

Result Valve Depth

Valve Series

Port Size

Ptro

Open Pres @ Surface

Close Pres @ Surface

Gas Rate (Unloading)

Unloading Liq Rate

Method: • •

Go to Design > Gas Lift Design in top menu. Enter the Gas Lift Design Data given.

•

Click on Perform Design.

Schlumberger

Max Valve Throughput

Valve Temp

Injection Pressure Drop

Cd

98


Case Study 7 – Gas Lift Design, Current Mandrel spacing: This case study will demonstrate the following workflow: 1. Install a Gas Lift Valve system in the tubing. 2. Perform a Deepest Injection Point operation to find the maximum depth that could be achieved. (Using Pinj = 1000 psig and Lift gas rate = 1.25 mmscf/d) 3. Perform a Gas Lift response operation to produce a graph of oil rate vs. lift gas rate. 4. Design the gas lift system using the current mandrel spacing.

Exercise 1: Installing a Gas Lift valve system, Deepest Injection Point Operation: Open the model created during the previous case study. Insert the following Gas lift valve system into the tubing user form. Equipment Gas Lift Valve Gas Lift Valve Gas Lift Valve Gas Lift Valve Gas Lift Valve Gas Lift Valve

MD 1500 2700 3600 4200 4700 5100

Properties IPO-1/8 IPO-1/4 IPO-5/16 IPO-5/16 IPO-5/16 IPO-5/16

Label BK-1 BK-1 BK-1 BK-1 BK-1 BK-1

Method: -Insert the spacing shown above in the tubing user form (in the down hole equipment tab). -Perform a Deepest Injection Point operation using a lift gas rate of 1.25 mmscf/d and an injection pressure or 1000psig.

Exercise 2: Generate Gas lift response curves Perform a Lift Gas Response operation to produce a graph of oil rate vs. lift gas rate (Use Minimum gas injection Delta P of 150 psi and 250 psi as the sensitivity and lift gas rates of 0-0,1-0,2-0,3-0,5-0,71-2-3-5 mmscf/d. Method: -In the Lift Gas Response user form select “injection at valve depth only”.

Exercise 3: Design the gas lift system using the current mandrel spacing Given the design conditions (Identical to case study 5), and the current mandrel spacing perform the gas lift design. Method: -Select current spacing in the design control tab prior to performing the design. Use 1.25 mmscf/d as the lift gas rate.

Schlumberger


Part 3: Network Modeling Tutorials

Schlumberger

99

100


Network Tutorial 1: Looped Gathering Network Overview The deliverability of a production network is to be established. The network connects three producing gas wells in a looped gathering system and delivers commingled product to a single delivery point. The engineer is asked to perform the following tasks:- Build a model of the network. - Specify the network boundary conditions. - Solve the network and establish the deliverability. The engineering data available is given at the end of this case study.

Step 1. Build a Model of the Network The following steps are to be carried out: -

Enter the engineering data for the first well. Copy the data to wells 2 and 3. Modify the data for well 3. Specify the composition at each production well. Connect the network together. Define the engineering data for each branch.

Open PIPESIM and go to to open a new Network model and save this in your training directory (e.g. as file c:\training\pn01.bpn). Use the production well button to place Well 1 in the work area as shown below.

production well button

production well

Double click on “Well_1” to reveal the components as shown below:-

Double click on the vertical completion to enter the inflow performance data. Enter a gas PI of 0.0004 mmscf/d/psi2. The reservoir temperature and pressure will be entered later when the network boundary conditions are specified (see page 2-5). Double click on the tubing and select “Simple Model” as the preferred tubing model. Define a vertical tubing with a wellhead MD of 0 and mid

Schlumberger


101

perforations TVD and MD of 4500 ft. The ambient temperatures are 130 °F at mid perforations and 60 °F at the wellhead. The tubing has an I.D. of 2.4". Note that the essential data fields are shown in red outline (if the fields are not outlined, then data entry in these fields is optional). Close the view of Well 1 to return to the network view. Select "Well_1" and using the commands copy "Well_1" to "Well_2" and "Well_3". Position the new wells as shown below:-

You will see that Wells 2 and 3 have adopted the data of Well 1. Double click on Well 3 and modify the completion and tubing data. Double click on the vertical completion to enter the inflow performance data. Enter a gas PI of 0.0005 mmscf/d/psi2. Double click on the tubing, and define a vertical tubing with a wellhead TVD of 0 and mid perforations TVD and MD of 4900 ft. The ambient temperatures are 140 °F at mid perforations and 60 °F at the wellhead. The tubing has an I.D. of 2.4". Close the view of Well 3 to return to the network view. The next step is to define the compositions at the production wells. Wells 1 & 2 are producing from the same reservoir and have the same composition. Well 3 has a different composition as shown in the data section at the end of the case study. The most efficient way define the compositions is to set the more prevalent composition (i.e. that for Wells 1 and 2) as the global composition and then to specify the composition of Well 3 as a local variant. The composition of Wells 1 and 2 is the same as that for the single branch model case study 5 and can be imported. First save the current network model. Open the single branch case study 5 (e.g. c:\training\ps05.bps). Use the menu and the export button to export the composition to a file called "comp1.pvt". Now close the single branch model case study 5. In the network model, use the menu and the import button to import comp1.pvt as the global composition. Click the right mouse button over Well 3, select fluid model and modify the composition to be locally defined as given at the end of this case study. The import function can be used again. Now position the sink and some junction nodes. Note that holding down the "Shift" key whilst placing junction nodes allows multiple placement, you should release the "Shift" key before the final placement. The network should now look like this:

Schlumberger

102


Using the branch button connect “J_1” to “J_2”. To do this, click on the branch button, then hold down the left mouse button over “J_1” and drag the mouse pointer to “J_2” before releasing the left mouse button.

branch button

branch connected

Double click on the arrow in the centre of "B1" to enter data for that branch. Now double click on the flowline to enter the following data:Rate of undulations: Horizontal distance: Elevation difference: Inner diameter: Wall thickness: Roughness: Ambient temperature:

10/1000 30,000 ft 0 ft 6" 0.5" 0.001" 60 °F

Close the "B1" window to return to the network view. As the looped gathering lines are all identical, the data for branch "B1" should be propagated to the other looped gathering lines. Select "B1" by clicking on the arrow in the middle of the branch and using the commands copy "B1" to "B2", "B3", and "B4". Position the new branches as shown below:

In order to reconnect a pasted branch, first pick the arrow in the middle of the new branch. You will see that highlight boxes appear at either end of the branch. Move the mouse pointer over the right hand

Schlumberger


103

highlight box, and you will see that the mouse pointer changes to an "up arrow" shape (↑). This end of the branch can then be dragged and dropped onto a junction node. Now connect the wells to the adjacent junction node and connect "J_4" to the sink as shown below:

Now enter the components and data for branch "B5". Branch "B5" comprises a liquid separator with an efficiency of 100%, a compressor with a pressure differential of +400 psi and an efficiency of 70%, an aftercooler with an outlet temperature of 120 °F and a delta P of 15 psi, and a flowline with the following properties:Rate of undulations: Horizontal distance: Elevation difference: Inner diameter: Wall thickness: Roughness: Ambient temperature:

10/1000 10,000 ft 0 ft 8" 0.5" 0.001" 60 °F

The equipment is located at "J_4" as shown below:-

Note that you should use the connector tool

to join the equipment together.

Task 2. Specify the Network Boundary Conditions First it is necessary to summarise the rules for specification of network boundary conditions. The network module solves the fluid pressures, temperatures, and flowrates around a network for a userspecified set of boundary conditions. The following definitions are used:Lone Node: A lone node is a node with only one branch connected, i.e. a production well, an injection well, a source or a sink.

Schlumberger

104


Boundary conditions: The fluid pressure, temperature, and flowrate at each lone node in the network. The following rules apply:Rule for Temperatures: The fluid temperature at all sources and the static reservoir temperature at all production wells must be specified by the user. The fluid temperature at all sinks and injection wells is always calculated by the network module. Rules for Pressures and Flowrates: There are two rules for specification of pressure and flowrate boundary conditions:Rule 1 - Degrees of Freedom. The total number of flowrates, pressures and PQ curves specified must equal the total number of lone nodes. Rule 2 - At Least one Pressure. A least one pressure must be specified at one of the lone nodes. All unspecified pressures and flowrates are calculated by the network module. In this case study, the above rules will be satisfied by doing the following -

Specify all the fluid inlet temperatures Specify all the fluid inlet pressures and the delivery pressure.

Use the menu to specify the boundary conditions below:Node Well_1 Well_2 Well_3 Sink_1

Pressure 2900 psia 2900 psia 3100 psia 800 psia

Temperature 130 °F 130 °F 140 °F (calculated variable)

Note that all of the flowrates will be calculated by the network module. It is also necessary to enter these values via the well view.

Task 3. Solve the Network and Establish the Deliverability First it is necessary to explain the network tolerance. A network has converged when the pressure balance and mass balance at each node is within the specified tolerance. The calculated pressure at each branch entering and leaving a node is averaged. The tolerance of each pressure is calculated from the equation:Ptol = I(P - Pave.)/Pave. x 100%I If all Ptol values are within the specified network tolerance then that node has passed the pressure convergence test. This is repeated for each node. The total mass flowrate into and the total mass flowrate out of a node are averaged. The tolerance is calculated from the equation:Ftol = I(Tot. mass flowrate in - Tot. mass flowrate ave.)/Tot. mass flowrate ave. x 100%I If the Ftol value is within the specified network tolerance then that node has passed the mass convergence test. This is repeated for each node. When all of the above conditions are satisfied, the network has converged. In this case study, the following steps are required:-

Schlumberger

PIPESIM Training Manual -

105

Set the network tolerance. Run the model. View the tabular reports. View the graphical reports.

Use the menu to set the network tolerance to 1%. Save the model, and then press the run button

.

When the network has solved you should get the message "pn01 - Finished OK". Press the "OK" button. Press the report tool button

and you will see that the sink gas flowrate is 41.55 mmscf/d.

More comprehensive tabular reporting is available using the summary file button

.

Select the flow route from "Well_3", branch "B3" and branch "B5". Hold the "Shift" key down in order to . The following pressure profile for effect a multiple selection. Then press the profile plot button these three branches should be obtained. The effect of the compressor at "J_4" on the system pressure can be seen:-

Schlumberger

106


Data Available Layout:The network is laid out as shown below:-

Completion and Tubing Data:Gas PI Wellhead TVD Mid Perforations TVD Mid Perforations MD Tubing I.D. Wellhead Ambient Temperature Mid Perforations Ambient Temperature

Wells 1 & 2 0.0004 mmscf/d/psi2 0 4500 ft 4500 ft 2.4" 60 °F 130 °F

Pure Hydrocarbon Components (Wells 1 & 2):Component Methane Ethane Propane Isobutane Butane Isopentane Pentane Hexane Petroleum Fraction (Wells 1 & 2):Name Boiling Point Molecular Weight (°F) C7+ 214 115 Aqueous Component (Wells 1 & 2):Component Water

Well 3 0.0005 mmscf/d/psi2 0 4900 ft 4900 ft 2.4" 60 °F 140 °F

Moles 75 6 3 1 1 1 0.5 0.5 Specific Gravity

Moles

0.683

12


Schlumberger

PIPESIM Training Manual Pure Hydrocarbon Components (Well 3):Component Methane Ethane Propane Isobutane Butane Isopentane Pentane Hexane Petroleum Fraction (Wells 3):Name Boiling Point (°F) C7+ 214

107

Moles 73 7 4 1.5 1.5 1.5 0.5 0.5

Molecular Weight

Specific Gravity

Moles

115

0.683

10.5

Aqueous Component (Well 3):Component Water


Data for Looped Gathering Lines (B1, B2, B3, and B4):Rate of undulations Horizontal distance Elevation difference Inner diameter Wall thickness Roughness Ambient temperature Overall heat transfer coefficient

10/1000 30,000 ft 0 ft 6" 0.5" 0.001" 60 °F 0.2 Btu/hr/ft2/°F

Data for Deliver Line (B5):Separator type Separator efficiency Compressor differential pressure Compressor efficiency Aftercooler outlet temperature Aftercooler delta P Flowline Rate of undulations Flowline Horizontal distance Flowline Elevation difference Flowline Inner diameter Flowline Wall thickness Flowline Roughness Flowline Ambient temperature Flowline Overall heat transfer coefficient

Liquid 100% 400 psi 70% 120 °F 15 psi 10/1000 10,000 ft 0 ft 8" 0.5" 0.001" 60 °F 0.2 Btu/hr/ft2/°F

Boundary Conditions:Node Well_1 Well_2 Well_3 Sink_1

Pressure 2900 psia 2900 psia 3100 psia 800 psia

Schlumberger

Temperature 130 °F 130 °F 140 °F (calculated variable)

108


Network Tutorial 2: Gas Transmission Network Features Illustrated • Gas Transmission Network • Two phase, compositional fluid modelling • Sources and a sink • Parallel flowlines • Pressure/Flow boundary conditions

Problem Outline Two sources, Supply_1 and Supply_2, are connected through a parallel pipeline system to a delivery station some 250km away. Each source has a fixed flowrate and each produces a gas. Fluid properties are modelled using a compositional fluid model.

General Data Different compositional fluids are produced by the sources. The delivery pressure is fixed at 855 psia. The ambient temperature for the field is 20 oC. Sources Supply_1 is flowing 15 mmsm3/d of gas at a temperature of 70 oC. The 1000 m flowline to the main trunk line has a 600 mm inner diameter, ID, with no elevation difference. Supply_2 is flowing 37 mmsm3/d of gas at a temperature of 55 oC. The 35000 m flowline to the main trunk line has a 900 mm inner diameter with no elevation difference. Parallel Flowlines The 250,000 m flowline (Line4) to the main trunk line has a 960 mm inner diameter with no elevation difference. The parallel, 256,000 m flowline (Line5) to the main trunk line has a 1024 mm inner diameter with no elevation difference. Flowline (Line2) The 2000 m flowline joining the two parallel lines at their start has a 949.9 mm inner diameter with no elevation difference. Flowline To Delivery The flowline from the end of the parallel line to the delivery has a 970 mm ID and continues for 2000 m to the delivery point. The required pressure for delivery is 855 psia. Note: All other parameters, including the heat transfer have been left as the default. The gas transmission network for is shown below.

Schlumberger


109

Figure 1 Case 2 Network Graphic Fluid Data Laboratory analysis has shown the fluids from the two supplies to have different compositions. Right click on each Supply and select Fluid Model. Ensure that the Local Compositional button is checked and Select Edit Composition. Enter the fluids as specified below:

Component Nitrogen H2S Carbon Dioxide Methane Ethane Propane Isobutane Butane Isopentane Pentane Hexane Heptane

Supply_1 Mol % 0.1 0.1 5.2 77.9 6.9 4.5 1.0 1.3 0.4 1.0 0.8 0.8

Supply_2 Mol % 0.2 0.0 3.0 79.8 8.4 4.2 2.1 1.0 0.7 0.4 0.2 0.0

Clicking the Phase Env. button will plot the phase envelope of the fluid.

Question 1 Determine the direction of flow in Line2, and the flowrate and fluid temperature at the delivery point. The objective is to determine the direction of flow in Line2 and the flowrate and temperature at the delivery point. Select Summary File from the Reports menu and scroll down to system summary section. This is shown below and you will see that Line2 is flowing in a forward direction (based on the initial flow direction - indicated by the arrow on the line) and that the flowrate and fluid temperature at the delivery point are 52 mmsm3/d and 20.2 oC respectively.

Schlumberger

110


Figure 3 Summary output

Question 2 Plot the pressure profiles for the 250 km parallel pipelines. Holding the Shift key, select Line 4 and 5 and click on the Profile Plot Icon: This plot is shown in figure 2

Figure 2: Pressure profiles for the 250 km parallel lines.

Question 3 Plot the temperature profiles for the 250 km parallel pipelines.

Schlumberger

PIPESIM Training Manual In the Plot Window, Select Series and change Pressure to Temperature for the Y-axis This plot is shown in figure 3

Figure 3: Temperature profiles for the 250 km parallel lines.

Schlumberger

111

112


Network Tutorial 3: Water Injection System Features Illustrated: • Injection network • Single phase • ESP lifted production well

Problem Outline A water production well feeds water into an injection system that consists of 6 injection points. The water is lifted from the production well by an ESP. Figure 1 schematically presents the layout of the studied water injection system. A Global black oil model with 100% watercut and DOD of 62.43 lb/ft3 is used in this case study.

Figure 1 Water Injection System The ESP can be added into the production well by selecting the ESP button (in Artificial Lift section) from the Tubing Details dialog that appears after double-clicking on the tubing in the Producer window.

General Data The fluid produced from the well (Producer) is a single phase black-oil with a watercut of 100%. The delivery pressures to each individual injection point are different. The ambient temperature for the entire network is 50°F.

Well Data The water production rate of the well is 15,000 STB/d and the temperature of the well is 200°F and reservoir pressure is 4000 psia. The well has a liquid productivity index (PI) of 100 STB/d/psi. Water is lifted from the production well by an ESP (Type: Centrilift, Model: IB700) with number of stages of 30 and at a speed of 3,600 rpm. The type of ESP can be specified by clicking on the Select ESP button in the Tubing Details dialog window.

Schlumberger


113

The ESP is located at a depth of 2,000 ft TVD and the water production well is at 6,000 ft TVD. The total measured depth along the tubing is 6,000 ft MD and the well has a 7” ID.

Flowlines to Injection Wells Flowline 1 is 150 ft in length with an ID of 8” and no elevation difference. It joins N1 to N2. Flowline 2 is 15000 ft in length with an ID of 6” and no elevation difference. It joins N2 to N3. Flowline 3 is 10000 ft in length with an ID of 6” and no elevation difference. It joins N2 to N4. Flowline 4 is 7000 ft in length with an ID of 4” and no elevation difference. It joins N2 to N5. All the flowlines are coated (heat transfer coefficient = 2 BTU/hr/ft2/F)

Delivery Sinks/Injection Wells All the delivery sinks are single injection wells with 1.995” ID tubing. Well_1 has a static pressure at 4400 psig and a temperature at 210°F. The injection well is at 7800 ft TVD and at 7800 ft MD. It delivers a total liquid flowrate of 2 STB/d/psi. Well_2 has a static pressure at 4500 psig and a temperature at 220°F. The injection well is at 7900 ft TVD and at 7900 ft MD. It delivers a total liquid flowrate of 4 STB/d/psi. Well_3 has a static pressure at 4400 psig and a temperature at 210°F. The injection well is at 7800 ft TVD and at 7800 ft MD. It delivers a total liquid flowrate of 6 STB/d/psi. Well_4 has a static pressure at 4500 psig and a temperature at 220°F. The injection well is at 7900 ft TVD and at 7900 ft MD. It delivers a total liquid flowrate of 8 STB/d/psi. Well_5 has a static pressure at 4400 psig and a temperature at 210°F. The injection well is at 7800 ft TVD and at 7800 ft MD. It delivers a total liquid flowrate of 3 STB/d/psi. Well_6 has a static pressure at 4500 psig and a temperature at 220°F. The injection well is at 7900 ft TVD and at 7900 ft MD. It delivers a total liquid flowrate of 5 STB/d/psi.

Fluid Data The fluid produced from the production well is a single phase blackoil (with 100% watercut) flow. Select Fluid Model under Setup and then Black Oil, click on the button of “Edit Black Oil Data” to specify the watercut and the dead oil density (DOD), the GOR is 0.0 scf/STB. Local flow correlations are used to model the wells (both production and injection ones) and flowlines. All the local flow correlations have used Duns & Ros correlation for both vertical and horizontal multiphase flow calculations. The objective of the case study is to determine the fluid (i.e. water in this case) distribution in an injection system from a single production well. Note: All other parameters should be left as the default.

Question 1: Use the Report Tool to summarize the results of interest • • • •

Click on the Report Tool Icon Select Clear Click on the Producing Well and each of the injector wells Select Config and remove all columns except Temperature, Pressure and Liquid Flow

This is show in Table 1

Schlumberger

114


Table 1: Summary of Results

Question 2: Plot the pressure profiles for all injection wells. This is shown in figure 2.

Schlumberger


Figure 2 Pressure profiles for all injection wells

Schlumberger

115

116


Part 4 – FPT Tutorials

Schlumberger


117

FPT Tutorial 1: Compositional Tank & Look Up Tables Objectives: The objective of exercise 1 is to familiarize the user with the FPT interface by building and running a simple case study where the reservoir depletion model is a compositional tank. Exercise 1 is divided into 8 subsections as detailed below: 1. 2. 3. 4. 5. 6. 7. 8.

Build a simple surface network. (3 producers, 1 sink). Build a compositional tank model. Link the network model to the FPT model. Map the wells from the reservoir to the network. Enter some simple field planning events. Solve the model. Format and view a graphical output. Format and view a Tabular output.

Build a Simple Surface Network: •

Use PIPESIM to create Network1.bpn in your training directory. The network is shown below:

Schlumberger

118


•

Three wells are connected to this reservoir. One of the well as modeled in PIPESIM is shown below:

•

Well Data (use the Simple Model option in PIPESIM to model each well): Mid Perfs Depth (Ft below sea bed) 3000 3000 3000

Well 1: Well 2: Well 3:

Tubing ID (in) 2 2 2

Ambient T (F) 60 60 60

Gas PI (mmscf/d/psi2) 1e-5 1e-4 1e-3

Res T (F) 250 250 250

Res P (psia) 4000 4000 4000

Note that all the wells in the PIPESIM network model should have no flow directional blocks. This is done by right clicking on the well in the network interface and selecting BLOCK: None.

•

Main Flow line Data:

These three wells connect to a single wellhead manifold on the seabed, which is at a depth of 1000 ft Subsea S.S. From this a horizontal flow line of 150000 ft length and 4 inch ID runs to the base of a riser of 5 inch ID that goes up 1000 ft to the sink.

Schlumberger


119

The Sink requires a minimum production pressure of 500 psia and should be able to handle the production from this reservoir. The surface ambient temperature is 60°F. The Flow line and riser system is modelled in PIPESIM as shown below:

•

The initial composition of the reservoir can be taken as 88% methane, 10% ethane, and 2% propane.

•

Create a compositional file called comp1.pvt in your training directory.

•

Check that the model solves successfully by running it. (Gas rate at sink: 26.824 mmscf/d with a network tolerance of 0.01 %)

•

Use the FPT button interface files.

within the PIPESIM network model to generate the necessary

Schlumberger

120


Build a Compositional Tank Model: •

Start FPT.

•

Use Save-As to save the model as Exer1.fpt in your training directory.

•

Select the Mode menu and choose Compositional Tank Models.

•

Select the Reservoir button

•

Enter the tank name: “tank1” and enter the following tank data:

. The compositional tank model user form will appear.

OGIIP: 50,000 mmscf. Reservoir Pressure (datum): 4000 Psia. Reservoir Temp (datum): 250 F. Reservoir Top (Datum depth: sea bed) 2800 ft Initial OWC (Datum depth: sea bed) 3300 ft Datum depth of perforation: 3000 ft Aquifer Replacement: 30% • Link the reservoir composition to the file comp1.pvt created above. •

The filled user form for “tank 1” is shown below:

Link the network model to the FPT model.

•

Use the Select Network Model(s) button the FPT model Exer1.FPT.

to attach the network model Network1.bpn to

Map the wells to the tank model. •

Use the Well mapping button below:

to map wells 1, 2, and 3 to tank 1. The user form is shown

Schlumberger


121

Enter some simple Field Planning Events.

Events Description: •

The simulation is to be run for 720 days in 60-day steps for the first 360 days and in 180 steps for the second 360 days.

•

Initially wells 1 and 3 are on, well 2 being turned on 60 days later.

Coding the events with FPT: •

Input the field logic using the field planning events button

Schlumberger

.

122


Modify the initial timestep to 60 days.

•

Note that it is necessary to switch wells 1 and 3 on at time=0 because the default initial condition of all wells is off.

Run the Model: •

Under build, advanced settings, tick Use NET restart file.

•

Run the model by selecting the run button

.

Format and view a Graphical Output:

Objectives: •

The objective is to produce a graph of the gas flow rate from each source and at the delivery for each time step.

Method: •

Once the simulation has finished, select the results viewer button

Schlumberger

.


Select plotting and plot for all wells and sinks. The graph is shown below.

Schlumberger

123

124


Format and View a Tabular output: •

Select the results viewer button

•

Click on the ‘Tanks’ radio-button.

•

Select Tank 1 from the list box.

•

Click on Customise to access the customise output dialog. Select Tanks and a custom summary number 1.

•

Remove any existing output from the right hand list box. Select HCIP gas and pressure from the first window. Click on OK and go back to the main window.

•

Click on Tank1 again and you should see two columns of data, HCIP gas vs. pressure. This table is shown below.

.

Schlumberger


125

Reservoir Pressure Vs Cumulative Gas Production:

Pressure (psia)

4500 4000 3500 3000 2500 2000 1500 1000 500 0 0

5000

10000

15000

Cumulative Gas Production(mmscf):

Schlumberger

20000

126


Exercise 2 Use of a Depletion table to model the reservoir: Objectives: The objective of exercise 2 is to modify the model developed in exercise 1 using a depletion table as an alternative to the tank method for modelling the reservoir. Exercise 2 is divided into 7 subsections as detailed below: 1. 2. 3. 4. 5. 6. 7.

Save the FPT model with a different name. Create a depletion table. Set up the table as the reservoir depletion model. Map the 3 wells to the table. Solve the model. (Using the same field planning events as in Exercise 1) Format and view a graphical output. Format and view a Tabular output.

Save the FPT model with a different name. •

Open exer1.fpt and save this as exer2.fpt

Create a depletion table: •

Select the Mode menu and choose Look-up tables:

•


•

. The look-up table user form will appear.

Select the Cum. gas as the Independent Properties and Pressure as the Dependant Properties, the user form should look as follow:

Schlumberger


•

Select Save table and save the table as bja1.tbl in your training directory.

•

Click on Edit table and the following text editor should appear.

Schlumberger

127

128


Enter the following data in the table. (These data could be pasted directly from an excel spreadsheet for example).

•

Save the table clicking on the menu file submenu save in the text editor.

•

Close the text editor.

Set up the table as the reservoir depletion model. •

Click on load table in the look-up table user form the table should appear in the user form as shown below.

Map the Reservoir to the wells: •

Map this reservoir to the wells in the same way as you did for the tanks

Run the simulation

Schlumberger


•

Run the simulation again.

Format and view the graphical output •

The graphical results for exercise 2 are shown below.

Schlumberger

129

130


Exercise 3: Field planning events logic and flow rate constrained wells: Objectives: The objective of exercise 3 is to enter more complex conditional logic and adding flow rate constraints on the wells. • •

The wells are going to be choked back if necessary so that they produce up to a maximum flow rate. Well 2 is only going to be turned on if the production at the FPSO drops below a given value.

Exercise 3 is divided into 7 subsections as detailed below: 1. 2. 3. 4. 5. 6.

Save the FPT model with a different name. Input the flow rate constraint. Modify the conditional logic. Run the model. (Using the same field planning events as in Exercise 1) Format and view a graphical output. Format and view a Tabular output.

Save the FPT model with a different name: •

Open exer2.fpt and save this as exer3.fpt.

Input the flow rate constraint: •

The PIPESIM network model controls the maximum flow rate from the well by choking the well back. It therefore must contain a choke to operate in the well description in the PIPESIM network model.

•

Select the ‘PIPESIM-Net models’ dialog and edit the PIPESIM network model.

•

Add a choke to each of the wells at the wellhead. Supply a temporary bean size of 3” for each choke (this will be overwritten by the field planning events logic). One of the wells as modified in PIPESIM is shown below:

Schlumberger


131

•

Exit the Network graphical interface.

•

Select the Flowrate Constraints button not the sink.

•

Now choose gas rate as the Limit type, and type in a rate of 11 mmscf/d in the Value text box.

•

Click on apply and this flow rate constraint will be imposed upon all of the wells. The flow rate constraints user form is shown below:

•

Click on OK to leave this User Form.

and select all of the wells (highlighting them), but

Modify the conditional logic: •

Use the field planning events editor to delete the event that currently turns on the well after 60 days.

•

Now add an Event that effectively says ‘turn on well 2 when the gas production rate at the sink drops below 21.8 mmscf/day’.

Schlumberger

132


Run the model: •


.

Format and view a graphical output: •


•


•

The graphical results are shown below.

Schlumberger

.


Schlumberger

133

134


Exercise 4: Use of a bean list to design a drilling schedule Objectives: The objective of exercise 4 is to design a simple drilling schedule to maintain the combined production of the three wells at or above at 19 mmscf/d/ for as long as possible. Exercise 4 is divided into 7 subsections as detailed below: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Save the FPT model with a different name. Delete the flow rate constraint. Modify the conditional logic so that only one well is active at timestep = 0 day. Create a “bean list” so that remaining wells get activated sequentially as production drops. Run the model. (Using the same field planning events as in Exercise 1) Format and view a graphical output. Observe that at time 900 the wells are “closed due to link with dead look up table”. Modify the look-up table. Restart the model at 840 days. Format and view a graphical output.

Save the FPT model with a different name: Open exer3.fpt and save this as exer4.fpt. Delete the Flow rate constraints:

Select the Flow rate Constraints button sink.

and select all of the wells (highlighting them), but not the

Select limit type = gas rate. Click on the remove button and the flow rate constraints will be deleted. Click on OK to leave this User Form.

Modify the conditional logic: •

Input the field logic using the field planning events button

•

Enter the following logic under schedule = NONE. (Note that the timestep has been changed to 960.)

Schlumberger

.


135

Create a bean list: • In the Drop-Down list schedule, highlight BEAN 01 and insert the following logic. • Bean list events will be triggered only once and once at a time in the order in which they have been entered in the user form. Run the Model:

Schlumberger

136



.

Format and view a graphical output: •


•

Select plotting and plot for all wells. The graph is shown below.

.

Observe that the wells are “closed due to link with dead look up table”. •

It can be seen that all the wells are closed from the time step 840 days.

•

Open the Field Planning Event window and the following should be seen at the end of the file.

Schlumberger


•

137

The wells have been shut due to the fact that the cumulative production of the wells at the timestep 900 days is above the maximum value of cumulative production in the reservoir table.

Modify the look-up table: •

To fix this, let’s add one more data points to our table as shown below (Click on the edit table

Schlumberger

138

PIPESIM Training Manual button, modify the table, save the table from the text editor, exit the text editor, click on load table to load the modified table):

Reservoir Pressure Vs Cumulative Gas Production:

Pressure (psia)

4500 4000 3500 3000 2500 2000

Series1

1500 1000 500 0 0

20000

40000

60000

80000

Cumulative Gas Production(mmscf):

Restart the model at 840 days: •

Select the Restart button

•

Highlight the timestep 840 and click on the restart button.

, the Restart simulation user form will appear as shown below:

Format and view a graphical output:

Schlumberger


The following graphical output should be obtained this time:

Schlumberger

139

140


Exercise 5: Design a drilling schedule to produce at a constant rate Objectives: The objective of exercise 5 is to design a simple drilling schedule to maintain the combined production of the three wells at EXACTLY 19 mmscf/d/psi^2 for as long as possible. Exercise 5 is divided into 7 subsections as detailed below: 1. 2. 3. 4. 5.

Save the FPT model with a different name. Add a field wide flow rate constraint. Run the model (Using the same field planning events as in Exercise 4) Format and view a graphical output. Format and view a Tabular output.

Save the PPT model with a different name: Open exer4.fpt and save as exer5.fpt.

Add a Field wide Flow rate constraint: •

The PIPESIM network model controls the maximum flow rate from the field by choking back the sink. It therefore must have a choke to operate in the main flow line description in the PIPESIM network model.

•

Click on the Select network models button

•

In the Select network models user form click on the edit button and modify the PIPESIM network model as shown below.

•

Select the Flowrate Constraints button

•

Highlight the sink.

•

Choose gas rate from the list box, and type in a rate of 19.1 mmscf/d in the box below.

•

Click on apply and this flow rate constraint will be imposed upon the sink.

•

Click on OK to leave this User Form.

Run the Model:

Schlumberger


141

Run the model.

Format and view a graphical output:

•


•


.

Exercise 6: Record some auxiliary properties: Objectives: The objective of exercise 6 is to record some auxiliary properties (Pressure drop across the choke and erosional velocity) while running FPT. In effect not all properties recorded by PIPESIM Net each run are stored in the FPT output files. These Auxiliary (nonrecorded) properties can be selected prior to an FPT run so that they are recorded in the FPT output file. Exercise 6 is divided into 7 subsections as detailed below: 1. 2. 3. 4.

Save the FPT model with a different name. Define auxiliary output. Run the model. (Using the same field planning events as in Exercise 4) Format and view a Tabular output.

Save the FPT model with a different name:

Schlumberger

142


Open exer5.fpt and save as exer6.fpt.

Define auxiliary output: •

Select the auxiliary properties button

•

The user form is divided into 4 windows the “branch list window” lists all the branches in the network; the “branches selected ” window displays the branch on which the user wishes to record auxiliary properties; the “auxiliary property” window lists all the auxiliary property that are available for the user to record, the “selected property window” display the chosen auxiliary properties to be recorded for the selected branches.

•

Select B1, well1, well2, and well3 by highlighting them in the “branch list window” and clicking on the Add button.

•

Highlight the 3 selected wells in the “selected branches window” and click on Erosional velocity Ratio in the “auxiliary properties window”.

•

Highlight the selected B1 branch in the “selected branches window” and click on Pressure drop across choke and Bottom hole pressure in the “auxiliary property window”.

•

Click on OK to exit the user form.

and the following user form will appear:

Run the model: Run the model by selecting the run button

.

Schlumberger


Format and view a tabular output: •

Click the customise button to produce the following tabular outputs.

Schlumberger

143

144


Schlumberger


145

FPT Tutorial 2: Black Oil Tank. Exercise 1: Objectives: The objective of exercise 1 is to familiarize the user with the FPT interface by building and running a simple case study where the reservoir depletion model is a Black Oil tank. Exercise 1 is divided into 8 subsections as detailed below: Build a Network model. Build a Black oil tank model. Link the network model to the FPT model. Map the wells from the reservoir to the network. Enter some simple field planning events. Run the model. Format and View a Graphical output. Format and View a Tabular output. Build a Simple Surface Network: Use PIPESIM network module to create BOTank.bpn in your training directory. The network model is shown below:

Six identical wells are connected to this reservoir. One of the wells as modeled in PIPESIM is shown below:

Schlumberger

146


Well Data: Reservoir Pressure = 3000 psi Reservoir Temperature = 200 F Completion Model – Well PI, choose Liquid PI of 10 STB/day/psi. Tubing Details – (use Detailed Model) MD ft 0 1000 2250 3500

TVD ft 0 1000 2000 3000

Temperature F 60

U value 2

200

2

Tubing ID inch 2.992 2.992 2.992 2.992

Rename this well Well_A1 and then copy and paste it to create wells Well_A2, Well_A3, Well_B1, Well_B2 and Well_B3. Link the wells to form the network.

Enter the pipeline data: Name Conn 1 Conn 2 Conn 3

Length, ft 2500 2000 100

Pipeline ID, inches 6 6 8

Ambient temperature for all surface conditions is 60 F. PumpBranch is made of two flow lines each of 1000 ft length and 6 inches ID. It also contains an adiabatic pump of 100% Efficiency and 100 HP and a Gas separator of 100 % efficiency between the two flow lines as shown below:

Schlumberger


147

Sink delivery pressure is 500 psi. The Global Black Oil composition for the network is Water Cut = 20%, GOR = 500 SCF/STB. Calibration data at Bubble point is Pressure = 3000 psi, Temperature =200 F, Saturation Gas = 500 SCF/STB. Note that all the wells in the PIPESIM network model should have no flow directional blocks. This is done by right clicking on the well in the network interface and selecting BLOCK: None. Check that the model solves successfully by running it. The following output is obtained at the sink (Tolerance: 0.2 %):

Use the FPT button

within the PIPESIM network model to generate the necessary interface files.

Build a Black Oil Tank Model: Start FPT. Use Save-As to save the model as BOTank.fpt in your training directory. Select the Mode menu and choose Black Oil Tank Models. Select the Reservoir button

. The compositional tank model user form will appear.

Create a new reservoir named PoolA with the following data:

Schlumberger

148


Schlumberger


Schlumberger

149

150


Create another new reservoir PoolB and input the following data:

Schlumberger


Schlumberger

151

152


Link the network model to the FPT model. Use the Net Models button BOtank.FPT. Map the wells to the tank model.

to attach the network model BOtank.bpn to the FPT model

Use the well mapping button to map well_A1, Well_A2, Well_A3 to PoolA and Well_B1, Well_B2, Well_B3 to PoolB. The user form is shown below:


once more. The compositional tank model user form will appear.

Select the Well completion details tab. Input the completion depths of the six wells as shown below:

Schlumberger


Click on edit to create the Water cut table (Watercut1) and GLR table (GLR1):

Select WellA1, WellA2, WellA3 and apply the Water Cut and GLR tables:

Schlumberger

153

154


Enter some simple field planning events: Events description: The simulation is to be run for 600 days in 60 days step. Initially Well_A1, Well_A2, Well_A3 are on Well_B1, Well_B2, Well_B3 are turned on 120 days later. The pump Horsepower is set to 600 Hp after 300 days. Coding the events with FPT: Input the field logic using the field planning events button

.

Set the initial timestep to 60 days. Note that it is necessary to switch well_A1, well_A2, well_A3 at time=0 because the default initial condition of all wells is off. The timestep is set to 1 day just before an event happens in order for the graph to represent accurately the surge in production that happens when: WellB1, WellB2, WellB3 are turned on. The pump power is stepped up from 100 Hp to 600 Hp.

Schlumberger


155

Run the Model Run the model by selecting the run button

.

View the Graphical Output Once the simulation has finished, select the results viewer button

.


Schlumberger

156


Schlumberger


157

FPT Tutorial 3: Look Up Tables Exercise 1: Objectives: The objective of exercise 1 is to build and run a simple set of case studies where the boundary conditions are provided to the network for a given number of simulations. (I.e. no reservoir depletion model is used) Exercise 1 is divided into 6 subsections as detailed below: Build 2 look up tables (PoolA and PoolB). Link the network model to the FPT model. Map the wells from the reservoir to the network. Enter some simple field planning events. Run the model. Format and View a Graphical output. Create 2 look up tables (PoolA and PoolB): Select the Mode menu and choose Case Studies: Select the Reservoir button

. The look-up table user form will appear.

Select Case as the Independent Properties and Pressure as the Dependant Properties, the user form should look as follows:

Schlumberger

158


Select Save table and save the table as PoolA.tbl in your training directory. Click on Edit table and the following text editor should appear.

Enter the following data in the table. (These data could be pasted directly from an excel spreadsheet for example). The date must lie between the 2 keywords “LOOKUPTABLEDATA” and “ENDOFTABLEDATA”

Schlumberger


159

Save the table clicking on the menu file submenu save in the text editor. Close the text editor. Select Unused2 in the case studies user form. Select Case as the Independent Properties and Pressure as the Dependant Properties, the user form should look as follow:

Schlumberger

160


Create the following table (Pool_B.tbl):

Map the Table to the wells: Map this table to the wells in the same way as you did in the black oil tank case study:

Schlumberger


161

Enter some simple field planning events: Wells A1, A2, A3 are on for cases 1-2; all wells are on for cases 3-5. Enter the following field planning events:

Run the simulation Run the simulation again. View the Graphical Output Once the simulation has finished, select the results viewer button

.


Schlumberger

162


The x-Axis is “Time” but for the case study mode “time” and “case” are treated the same.

Schlumberger


163

FPT Tutorial 4: Daily Contract Quotas (DCQ) Exercise 1: Objectives: The objective of exercise 1 is to familiarize the user with the FPT_DCQ interface by building and running a simple case study where the reservoir depletion model is a Compositional Tank. Exercise 1 is divided into 8 subsections as detailed below: Build a Network model (containing 5 identical wells). Build a Compositional tank model. Link the network model to the FPT model. Map the wells from the reservoir to the network. Enter some simple field planning events. Run the model. Format and View a Graphical output. Fill in the DCQ user form. Build a simple surface Network: Use PIPESIM network module to create DCQ.bpn in your training directory. The network model is shown below:

Six identical wells are connected to this reservoir. One of the wells as modeled in PIPESIM is shown below:

Schlumberger

164


Well Data:

Schlumberger


Link the wells to form the network. Enter the pipeline data:

Schlumberger

165

166


Sink delivery pressure is 2000 psi. The Global composition for the network is shown below: Nitrogen: 3.15 Carbon Dioxide: 1.34 Methane: 85.05 Ethane: 5.14 Propane: 2.19 Isobutane: 0.35 Butane: 0.7 Isopentane: 0.24 Pentane: 0.24 Hexane: 0.19 C7+: 1.41 Name C7+

BP (F) 188

MW 90

SG 0.75

TC (F) 520

PC (psia) 512

Omega 0.29

Note that all the wells in the PIPESIM network model should have no flow directional blocks. This is done by right clicking on the well in the network interface and selecting BLOCK: None. Create a PVT file DCQ.pvt. Check that the model solves successfully by running it. The following output is obtained at the sink (Tolerance: 1 %):

within the PIPESIM network model to generate the necessary interface files. Use the FPT button Build a Compositional Tank Model: Start FPT. Use Save-As to save the model as DCQ.fpt in your training directory. Select the Mode menu and choose Compositional Tank Models. Select the Reservoir button (Composition file: DCQ.pvt).

. Fill in the compositional tank model user form as shown below

Schlumberger


167

Link the network model to the FPT model. Use the Net Models button to attach the network model DCQ.bpn to the FPT model DCQ.FPT Map the wells to the tank model. Use the well mapping button shown below:

to map a1, a2, a3, b1, b2, and b3 to res01. The user form is

Schlumberger

168


Enter some simple field planning events: All wells are turned on at the start of the simulation.

Run the model: Run the model by selecting the run button Format and View a Graphical output:

.

Schlumberger


169

Fill in the DCQ user form: Click on the menu MODE submenu DCQ and the DCQ user form will appear:

Enter the following data in the user form (The date can be entered under the following format 01/01/2000 – the Time column will then be filled automatically):

Schlumberger

170


The typical contract is defined by the following: The obligation, which is the average production rate (DCQ in mmscf/d) that will be purchased by the transmission company (or consumer) over the nomination period. The take factors that are the fractions of the DCQ that will be bought in any given period. The following equation must be respected: n

α i ⋅ DCQ

i =1

n

∑

= DCQ

Where: n = Number of time period considered. αi = Take fraction for the period i. The swing factors: Factors, which multiplied by the DCQ volume, gives the peak daily demand rate expected by the purchaser in any given period. The peak daily demand rate can be much higher than the average daily take. Minimum specified delivery pressure. The swing and take patterns are drawn by linking all the swing and take factors together against time. A typical swing and take pattern over a period of one year can be seen below:

Schlumberger


171

1.6 1.4 1.2 1 Swing Take

0.8 0.6 0.4 0.2 0 0

100

200

300

400

Time (Days).

DCQ calculation procedure: Start of Iteration: The engine takes the initial DCQ value (mmscf/d) as the boundary condition of the sink. production allocation from each well is calculated in a PIPESIM-net simulation determined. corresponding outlet pressure is also calculated.

The The

Deliverability check for the month: Using the “% take” value for the month, FPT calculates the cumulative flow taken from each source for the 1st month of the contract. Well Name: Well A: Well B: Well C: Total:

Flow rate produced by each source when producing DCQ: 5 mmscf/d. 8 mmscf/d. 12 mmscf/d. DCQ = 25 mmscf/d.

% Take value for August: 0.5 0.5 0.5 0.5

Flow rate produced by each source in August: 2.5 mmscf/d 4 mmscf/d 6 mmscf/d 12.5 mmscf/d

Cumulative flow rate taken in August: 75 mmscf 120 mmscf 180 mmscf 375 mmscf

Using the cumulative flow rate taken from each well calculate the pressure of the reservoir(s) at the end of the period. The deliverability at the end of the month Q2 is calculated using the reservoir pressure (s) at the end of the period at each of the well and Pout at the sink (minimum specified delivery pressure). If the deliverability is less than the DCQ multiplied by the swing factor abort the iteration and repeat step 1 with a more suitable initial DCQ guess (Lower DCQ). If the deliverability is more than the DCQ multiplied by the swing factor do a deliverability check for the following period. If no Pinch point has been encountered over the length of the nomination period choose a higher DCQ and return to point one.

Schlumberger

172


Run the DCQ operation: Run the operation by pressing the

button in the DCQ user form.

The Messages window will look as shown below during the run:

FPT converges on a solution after four iterations. Observe the results: The Calculated DCQ that the asset can guarantee and the corresponding pinch point can be seen on the DCQ Calculation user form.

Schlumberger


173

Click on the results tab to display the results (Calculated DCQ value of 98.818 mmscf/d, Pinch point in December)

Schlumberger

174


Part 5 – Single Branch Case Studies – Worked Answers

Schlumberger


175

Worked Answers: Case Study 1 – Oil Well Design Exercise 1 Open PIPESIM and Open a new Well Performance Analysis module from the File menu. Save the model as Case Study 1. The first step is to create the black-oil model. From the Setup Menu, select “Black Oil…”. Using the given Black Oil PVT data, enter the data into the dialogue box as shown below:

Click on the Export button. This will add the fluid model to the data-base. Note that if any changes are made to the fluid, you must click on the Export button. Now that the basic black oil model has been defined, the next step is to create the well model. Click and drag the objects to create a well model as shown below:

Schlumberger

176


To enter the tubing data, double click on the tubing and select “detailed model”. Enter the given deviation data into the model as per the below screen:

Click on the “Geothermal Survey” tab and enter in the given information as per the below screen:

Now click on the “Tubing Configurations” tab and enter the data as per the below table:

Schlumberger


177

Now that all the required tubing information has been entered, the next step is to enter the reservoir and inflow data into the model. Double click on the completion icon and enter the data as shown below. Note that inflow model used is a Well PI, this can be selected from the drop-down menu. Also click on the radio button to “use non-linear correction below the bubble point”.

The basic oil well model has been defined. It is now possible to run some PIPESIM operations. To answer the questions, a Pressure/Temperature profile operation will

Schlumberger

178


be run. From the Operations menu, select “Pressure/Temperature Profile…” To calculate the production rate for a well-head pressure of 300 psia, enter the information into the dialogue box as shown below:

Hit the “Run Model” button, and the following plot will be generated:

The above shown screen shows the pressure profile down the length of the tubing. You can plot other variables on the chart by using the “Series” drop down tab.

Schlumberger


179

To obtain the production rate, flowing BHP and flowing WHT, close the plot then from the main PIPESIM page, then select Summary File from the Reports menu. The below shown screen will be generated:

From the above shown ASCII file, the results below can be obtained: Result Wellhead Pressure Production Rate ? Flowing BHP ? Flowing WHT ?

Schlumberger

300 psia 7438 bbl/d 2670 psia 132 oF

180


Exercise 2 Nodal analysis will now be performed to determine the operating point and AOFP of the well. A nodal analysis icon will need to be inserted into the model. Enter a NA point as shown below:

From the Operations menu select “Nodal Analysis…”. Enter the data as shown in the below dialogue box.

Click on the “Run Model” button and the below shown Nodal Analysis plot will be generated:

Schlumberger


181

To determine the operating point flowrate and BHP, and the AOFP, click on those points on the chart and read the results from the bottom right hand corner of the screen. The results are as follows: Result (Outlet) Wellhead Pressure Operating Point Flowrate ? Operating Point BHP ? AOFP ?

Schlumberger

300 psia 7438 stb/d 2670 psia 20400 stb/d

182


Exercise 3 The black oil model used so far only contains the minimum information required for fluid model definition. In this exercise the black oil model will be calibrated using more detailed data. From the Setup menu select “Black Oil…”. Now click on the “Viscosity Data (Optional)” tab at the top of the dialogue box. In the Dead Oil Vicosity section, select “User’s Data” from the drop-down menu. Enter the given data as shown below:

Now go to the Advanced Calibration Data (Optional) tab from the top of the dialogue box and enter the data as shown below:

Schlumberger


183

Go back to the Black Oil Properties tab and click the Export button. This will update the fluid into the database. Click OK. From the Operations menu select “Pressure/Temperature Profile…”. Repeat the previous operation and inspect the depth vs pressure chart. As shown in Exercise 1, from the Summary file you can find the following results: Result Wellhead Pressure Production Rate ? Flowing BHP ? Flowing WHT ?

Schlumberger

300 psia 6826 stb/d 2747 psia 129

184


Exercise 4 An FGS survey and well test data are available for this well. In this exercise we will use the FGS data to select the most suitable vertical multiphase flow correlation. From the Operations menu select “Flow Correlation Matching..”. Enter the given information as per the below dialogue box (we will use only Beggs & Brill Revised, Duns & Ros, and Hagedorn & Brown).

Click on the “Run Model” button and the following plot will be generated:

Schlumberger


185

From the above plot, it appears that the best correlation is Hagedorn & Brown. Close the plot then from the Setup menu, select “Flow Correlations..”. As shown below, change the vertical multiphase flow correlation to Hagedorn & Brown:

The BHP using the Hagedorn & Brown can be approximated from the profile plot generated earlier, or for the exact calculation you can run another “Pressure/Temperature Profile…” as done in the earlier exercises. The BHP can be read from the Summary File (Reports menu). Using the Hagedorn & Brown correlation, the results are as follows: Result Wellhead Pressure Vertical Correlation ? Flowing BHP ?

300 psia Hagedorn & Brown 2532 psia

Schlumberger

186


Exercise 5 Given the correct flow correlation chosen in Exercise 4, Exercise 5 involves finding the correct IPR that matches the test data used in Exercise 4. The known reservoir pressure is 4600 psia. We will determine the new PI and the AOFP. To determine the PI, System Analysis will be performed. In this exercise, a plot of production rate vs PI will be generated given the known reservoir pressure of 3600 psia and the known wellhead pressure of 300 psia. From the Operations menu, select “System Analysis…”. Enter the given information into the dialogue box as shown below:

Click on the “Run Model” button and the below system plot will be generated:

Schlumberger


187

From the above chart, the PI can be read from the plot at a liquid flow-rate of 6500 STB/d. The correct PI is 6.059 STB/d/psi. To determine the AOFP, Nodal Analysis can be performed using the PI as calculated above (to do this, the new calculated would need to be entered into the completion model prior to performing Nodal Analysis). Nodal Analysis can also be used to determine the correct PI. As per Exercise 2, from the Operations menu select “Nodal Analysis…”. Enter the information into the dialogue box as shown below:

The below Nodal Analysis plot will be generated:

Schlumberger

188


From the above Nodal Analysis plot the PI that corresponds to a liquid flowrate of 6500 STB/d can be approximated as 6 STB/d/psi. At this PI, the AOFP is 15224 STB/d. Result Wellhead Pressure PI ? AOFP ?

300 psia 6 STB/d/psi 15224

As mentioned above, note that in the case when the PI is calculated using System Analysis, if the user wishes to use Nodal Analysis to determine the AOFP, then the calculated PI from the System Analysis would need to be entered into the completion (as per Exercise 1) prior to performing the Nodal Analysis. The PI of 6 will be used in the remaining exercises, ensure that it is changed in the completion.

Schlumberger


189

Exercise 6 Given the current wellhead pressure, we will determine the watercut at which the well will die. This will be performed using System Analysis. From the Operations Menu, select “System Analysis..”. Enter the given data into the dialogue box as shown below:

Click on the “Run Model” button and the below System Plot will be generated:

Schlumberger

190


As can be seen from the above plot, the last converged solution is at 60% watercut. This is because for a watercut of 70%, the well will not flow. For our purposes, we will take the answer to be 60%. To determine the exact watercut at which the well will die, the operation could be repeated using watercut values from 60% to 70% as the sensitivity. Result Wellhead Pressure Water Cut ?

300 psia 60 %

Note that Nodal Analysis could also be used to determine the watercut at which the well will die. To do this, select the Nodal Analysis operation from the Operations menu as done previously, and perform nodal analysis by selecting the watercut as the outflow sensitivity and entering watercut values into the table. From the Nodal Analysis plot, the watercut at which the well dies can be determined by identifying the first outflow curve that does not cross the IPR curve at any point (as determined above, this will be a water cut between 60% and 70%).

Schlumberger


191

Exercise 7 In this exercise we will examine how this well responds to Gas Lift. We will introduce a gas lift injection point at 8000 ft MD in the tubing. Using watercuts of 10% and 60%, we will determine the liquid production rate for a range of gas lift injection rates. Double click on the tubing, and select the “Downhole Equipment” tab. Enter the data as per below:

Click on the “Properties” button and enter the given data as shown below (note: default injection rate must be given - use 1 MMSCFD):

Schlumberger

192


Click OK and from the main PIPESIM menu select the System Analysis operation from the Operations menu. To see the effect of the gas lift rate at various watercuts, select the “X-axis variable” to be the lift gas rate and the “Sensitivity Variable” to be the watercut. Enter the given data as shown below:

Click on the “Run Model” button. The below shown System Plot will be generated.

From the above generated plot, the below answers can be determined:

Schlumberger


193

Result Gas Lift Rate (mmscf/d)

Water cut = 10% Liq. Prod. Rate (stb/d)

0.5 1 1.5 2

7163 7661 8002 8257

Schlumberger

Water cut = 60% Liq. Prod. Rate (stb/d)

4708 5771 6411 6870

194


Worked Answers: Case Study 2 – Well Performance Analysis – Nodal Analysis Exercise 1 In this exercise we will build a single branch model and perform Nodal Analysis. The first step is to create a new single branch model by selecting “Well Performance Analysis” from the “New” option from the File menu. The first step is to define and characterize the fluid model. From the Setup menu select “Black Oil…”. Enter the given information as shown below.

Click on the “Export” button then click OK. This new fluid model is now in the fluid model database. Now build a simple model as per the below shown screen-shot:

Schlumberger


195

Double click on the completion icon and select Pseudo Steady State as the inflow model and then select “Liquid” as the basis for the IPR. Check the box “Use Vogel below bubble point”. Enter the given information as per the below table:

Now that the completion has been defined, click OK then double click on the tubing. Select “Simple model” from the drop-down list then enter the information into the model as shown below (when entering the Perforation information into the dialogue box, enter the TVD first then the MD and allow PIPESIM to calculate the angle from the kick-off point).

Schlumberger

196


Now all the required data has been entered into the model. Using Nodal Analysis, we will now determine the flowing bottom hole pressure and the production rate given a wellhead pressure (250 psia). From the Operations menu, select “Nodal Analysis…”. Enter the data and fill in the dialogue box as shown below (leave the sensitivity fields blank).

Click on the “Run Model” button. The following plot should be generated.

From the plot, the flowing bottom hole pressure and production rate can be determined by clicking on the operating point and viewing the results in the bottom right hand corner of the chart.

Schlumberger


The results are as follows: Result Wellhead Pressure Production Rate ? Flowing BHP ?

Schlumberger

250 psia 780 2420

197

198


Exercise 2 In this exercise we will investigate the increase in production through stimulation and gas lift using Nodal Analysis. Firstly, a gas lift injection point must be entered into the model. Double click on the tubing, then in the “Artificial Lift (Optional)” field, click on the “Gas Lift” button and enter a depth of 4500 ft into the field as shown below.

Now click on the “Properties” button, and enter the data as follows (we will set a default gas lift rate of 0 MMSCFD here).

Schlumberger


199

From the Operations menu, select “Nodal Analysis…”. Enter the data as shown below:

Click on the “Run Model” button and the following plot should be generated:

Schlumberger

200


From the above plot, the following results can be determined: Outlet Pressure = 250 psia.


0 (base) 780 1070 1430

Gas Lift (mmscf/d) 0.5 1.0 1090 1180 1430 1530 1790 1910

Schlumberger

2.0 1240 1590 1980


201

Exercise 3 In this exercise the different flow correlations will be investigated. The Beggs and Brill correlation has been used so far. The Mukherjee and Brill correlation accounts for the effects of viscosity, which for this case may be significant because the oil is relatively heavy. We will repeat the Nodal Analysis from Exercise 2 using the Mukherjee and Brill vertical flow correlation. From the Setup menu, select “Flow Correlations…”. In the Vertical Flow (Multiphase) section, select Mukherjee and Brill from the “Correlation” drop down menu, as per the below screen.

We will now repeat the Nodal Analysis as performed in Exercise 2. From the Operations menu, select “Nodal Analysis…”. The inflow and outflow sensitivity definitions should still remain from Exercise 2 (if not, re-enter them as per Exercise 2). Click on the “Run Model” button. The below chart should be generated:

Schlumberger

202


From the above generated chart, the following results can be determined. Outlet Pressure = 250 psia. Oil Production Rates (STBD)– Mukherjee & Brill:


0 (base) 690 980 1320

Gas Lift (mmscf/d) 0.5 1.0 1010 1120 1320 1460 1690 1840

2.0 1220 1570 1960

The above results can be compared to the results from Exercise 2. The discrepancy between the Beggs and Brill correlation and the Mukherjee and Brill correlation ranges from 1 – 15%. However, both cases agree fairly well in terms of the relative added benefit shown by sensitivity cases. Notice that in changing the flow correlation, the inflow curves remain unchanged. This is because Nodal Analysis “de-couples” the system, creating two independent components. Ultimately, project economics and future production potential based on reservoir conditions will weigh heavily in the final decision.

Schlumberger


203

Worked Answers: Case Study 3 – Gas Well Performance Task 1: Water content at saturation (Reservoir conditions) Open a new PIPESIM single branch model. Firstly the PVT information will be entered. From the Setup drop-down menu select “Compositional”. This opens the compositional PVT editor. You can enter in the gas well fluid composition as per the given composition. For the purposes of the first task, you must enter an amount of water; use a value of 20 moles. The compositional editor is shown below.

After entering the water free composition in the lower table (in moles, total excluding water equals 100) and a nominal 20 moles of water in the top table (these numbers will be changed later after determining the saturated water composition), click on the “Single Point Flash” tab across the top of the dialogue box. Check the PT radio button as shown below, and enter in the reservoir pressure and temperature. Press the “Perform Flash” button, and the results water saturated composition will be shown in the vapour stream.

Schlumberger

204


The water content at the saturation point at reservoir conditions is given below (this is the renormalised content): Pres = 4,600 psia, Tres = 280oF % Water 1.80% Now enter this new composition into the composition editor (note that the aqueous fraction should be entered into the top section). Task 2: Phase envelope: It is possible to generate a phase diagram by pressing the “Phase Envelope” button from the “Component Selection” screen. The following phase diagram should be generated:

Task 3: Results To run a case, the first step is to construct a model using the PIPESIM icons as arranged below:

Schlumberger


205

Prior to running a model, the reservoir, inflow and tubing data must be entered into PIPESIM. Click on the completion icon to enter in the reservoir and inflow information. The below dialogue box should come up. Enter in the reservoir pressure and temperature, then select the inflow model from the dropdown menu. Enter the Gas PI as per the data sheet.

After entering the reservoir and inflow information, you should now enter in the tubing information. Click OK from the on the above screen then double-click on the tubing. Select “Simple Model” from the drop-down menu then enter the information as per the data sheet into the dialogue box, as shown below:

Schlumberger

206


Schlumberger


207

All required information has now been entered into the model. It is now time to run the model. From the Operations menu select “Pressure/Temperature Profiles”. To calculate the rate for a given outlet (well-head) pressure of 800 psia, click on the radio button next to “Gas Rate”. Now enter in 800 psia into the box next to the “Outlet Pressure” radio button as shown below:

Click on the “Run Model” button. This will run the model and give a profile plot for the flow path. To obtain the results, close the plot and from the Reports drop-down menu, select “Summary File” From the Summary File, the below answers can be obtained: QG Pwf BHT WHT

Po = 800 psia 19.4 MMSCFD 1,318 psia 228oF 172oF

Schlumberger

208


Worked Answer Exercise 2: Task 1: Calculated inflow parameters for Back-Pressure Equation from DST data: Instead of using the Gas PI as the inflow model, the Back Pressure equation will be used. The back pressure equation allows generation of a pseudo steady state gas well IPR model using test data. The parameters will be determined by fitting the data to a curve using the following formula: 2

2 n

Q = C(Pws - Pwf )

To change the inflow model, double click on the completion. This will bring up the dialogue box as shown in Exercise 1. From the drop-down menu next to “Model Type” under “Completion Model”, select BackPressure Equation. To calculate the C and n parameters, click on the button “Calculate/Graph”. Enter in the given DST data into the dialogue box as shown below, and click OK. The calculated values will then be shown.

The calculated parameters are listed below: Parameter C Parameter n

Pres = 4,600 psia 8 x 10-7 1

Task 2: Results using Back-Pressure Equation and DST data: You can now run the model using “Pressure/Temperature Profiles” in the same way as shown for Exercise 1. The results can again be obtained from the Summary File, and are summarised below: Results: QG Pwf BHT WHT

Po = 800 psia 15.7 MMSCFD 1,263 psia 226oF 167oF

Schlumberger


209

Worked Answer Exercise 3: Task 1: Bottom-hole Nodal Analysis with tubing ID set as outflow sensitivity: To perform the Nodal Analysis at the sand-face, a Nodal Analysis icon will need to be installed at the bottom of the tubing (if not already done so). From the Operations Menu, select “Nodal Analysis”. Enter the given data into the dialogue box as shown below then click on the “Run Model” button.

The following bottom-hole Nodal Analysis plot will be shown. The below is a Nodal Analysis plot at bottom-hole for different tubing sizes:

Schlumberger

210


Task 2: Erosional velocity ratio: Run the model from the “Pressure/Temperature Profiles” option from the Operations menu, using the tubing size as the sensitivity (as shown below). Use an outlet pressure of 800 psia.

The pressure temperature profile plot of the system will be generated. To generate a plot of depth versus the erosional velocity ratio, change the x-axis to Erosional Velocity Ratio by selecting “Series” from the top toolbar and selecting “Erosional Velocity Ratio” from the “Select X Axis” drop-down menu. Click OK and the following chart should be obtained.

Schlumberger


211

Task 3: Results for 3.958” ID tubing: The below results can be obtained from the Summary File. QG Pwf BHT WHT

3.958” ID tubing 15.7 MMSCFD 1,236 psia 226oF 164oF

Use the generated chart to determine the erosional velocity ratio at the wellhead for the 3.958” ID tubing. Well-head Erosional velocity ratio 0.788

Worked Answer Exercise 4: Task: Gas rate vs Reservoir Pressure for different tubing sizes: From the Operations Menu select “System Analysis”. Enter the given information into the dialogue box as shown below:

Click on the “Run Model” button and the below chart should appear. From this chart it also appears that the 3.958” ID tubing is likely the optimum tubing size.

Schlumberger

212


Worked Answer Exercise 5: Task: Calculated choke Size: A choke and flow-line can be entered into the model by the usual click and drag method. Double click on the flow-line and enter the given data as shown in the below dialogue box:

To determine the choke size to give the desired outlet (ie manifold) pressure of 710 psia, the “Pressure/Temperature Profiles” option can be used. Use the choke size as the sensitivity, and calculate the outlet pressure for the given rate of 15.7 MMSCFD, as per the below dialogue box:

Click on “Run Model” then look in the Summary File (shown below). Look for the choke size that results in an outlet pressure of 710 psia (and check that that wellhead pressure is 800 psia).

From the Summary File, the choke size that will give an outlet pressure of 710 psia is 1.5”. Note that the well-head pressure is still 800 psia upstream of the choke.

Schlumberger


Choke size

213

Po = 710 psia 1.5”

Worked Answer Exercise 6: Task 1: Water content at saturation (Reservoir conditions) at new composition: Save the model as a new name. Enter the new composition using the composition editor and determine the fraction of water at the saturation point of the gas (as per the same method as Exercise 1 Task 1). The answer is as follows: Pres = 4,600 psia, Tres = 280oF % Water 1.88% Task 2: Best Flow Correlation: The choke and flow-line should be de-activated (so that the outlet pressure of 800 psia represents the well-head pressure). To de-activate an object, right click it and select Active, this will de-activate the object (it will now read “inactive”). From the operations menu, select “Flow Correlation Matching”. Enter the given data in the dialogue box as shown below:

Click on “Run Model”, and the following chart will be generated:

Schlumberger

214


From the above chart it is clear that the Duns & Ros correlation is the most suitable. To determine the mean arithmetic and mean absolute differences, look at the bottom the Output File The results are as follows: Po = 800 psia Best Correlation Mean arithmetic difference (%) Mean absolute difference (%)

D&R 0.89 0.89

Task 3: Results using new correlation and heavier composition: Using the “Pressure/Temperature Profile” option from the Operations Menu, with an outlet pressure of 710 psia (remember to activate the flow-line and choke) as per the method described previously, the results can be generated. The bottom-hole flowing pressure and gas flow-rate can be read from the Summary File as shown in the previous exercises, and the actual liquid flow-rate at the mid-perfs and outlet can be found in the Output File The results are as follows: Po = 710 psia QG 13.3 MMSCFD Pwf 1,361 psia QL @ mid-perfs (act) 2,292 bbl/d QL @ outlet (act) 2,690 bbl/d

Worked Answer Exercise 7: Task 1: Liquid Volume Fractions and Liquid Hold-up Fractions:

Schlumberger


215

Re-run the Pressure/Temperature Profile as performed in Exercise 6, Task 3. To determine the liquid volume fraction and liquid hold-up fraction at the specified points, look in the Auxiliary Output Page at the bottom of the output file:

The following results can be obtained: Liquid Volume Fraction, Po = 710 psia xVL @ bottom-hole 0.0717 xVL @ WH 0.0585 xVL @ end flow-line 0.0500 Liquid Hold-up Fraction, Po = 710 psia xHL @ bottom-hole 0.4080 xHL @ WH 0.0837 xHL @ end flow-line 0.1085

Task 2: Flow Regime and Map for end of flow-line: To obtain a flow-map, a report tool needs to be entered into the model at the end of the flow-line.

Double click on the report icon and check the “Flow Map” check-box as shown below:

Schlumberger

216


The model needs to be re-run, this can be done by pressing the “Run” button on the main tool-bar (this will re-run the latest operation, in this case the Pressure/Temperature Profile from Exercise 7, Task 1). Look at the bottom of the Output File to see the flow map as shown below:

From the above flow-map , the flow-regime at the end of the flow-line can be determined (this can also be determined by looking elsewhere in the Output File, as well as the Summary File). Liquid Volume Fraction, Po = 710 psia Flow regime end FL Intermittent

Worked Answer Exercise 8: Task 1: PT path on phase diagram: To generate phase diagram with the PT flow path super-imposed on it, first of all double click on the report icon and select “Phase Envelope”. Re-run the model using “Pressure/Temperature Profiles” (this will re-run the model from Exercise 7, Task 2). In the profile plot that is generated, from the Series option in the top toolbar, change the y-axis to pressure and the x-axis to temperature. The below phase diagram with the fluids PT path should be generated:

Schlumberger


217

Task 2: Hydrate formation? From the above shown phase diagram, it can be seen that the operating line does not cross the hydrate formation line. This means that hydrates will not be produced anywhere in the production system up to the manifold (represented by the outlet). Ambient Temp = 30oF Hydrate formation No

Worked Answer Exercise 9: Task 1: Pressure drops for heavier composition: The pressure drop across the reservoir, tubing, choke and flow-line can be determined from the Summary File, as shown below. Use a rate of 13 MMSCFD and run a Pressure/Temperature Profile operation (and select Outlet Pressure as the calculated variable). The tubing pressure drop is the bottom-hole flowing pressure minus the well-head pressure, as determined from the above shown Summary File output. Heavier composition (13 MMSCFD) 2,803 psia ∆P Reservoir 601 psia ∆P Tubing 76 psia ∆P Choke 2 psia ∆P Flow-line

Schlumberger

218


Worked Answer Exercise 10: Task: Results using Rigorous Flash: To use the “Rigorous Flash” option, from the Setup Menu select “Flashing…”. Check the “Always Rigorous Flash (slow)” for both the Temperature Energy Balance and Physical Properties as per the below shown dialogue box:

Click OK then re-run the model from “Pressure/Temperature Profiles” using an outlet pressure of 710 psia. Compare the results from the Summary and Output files and the phase diagram to the results from the same operation when the Interpolation option was used instead of rigorous flashing (ie Exercise 6 Task 3, and Exercise 8 Tasks 1 and 2). The results are as follows: Po = 710 psia QG 13.3 MMSCFD Pwf 1,361 psia QL @ mid-perfs (act) 2,291 bbl/d QL @ outlet (act) 2,672 bbl/d PT path from reservoir to end of flow-line plotted on new phase diagram using the Rigorous Flash option:

Hydrate formation? Ambient Temp = 30oF Hydrate formation No

Schlumberger


219

Note that the results are similar to when the interpolation option is used, except the rigorous flash predicts more of the retrograde condensation to occur prior to the fluid reaching the sand-face, as determined from the actual liquid flow-rate at the mid-perfs (compare to the results from Exercise 6 Task 3). The prediction is 4,112.4 bbl/d vs 3,150.3 bbl/d for the interpolation option. The other results are quite similar, but the difference described above illustrates the how the Rigorous flash can be applicable, especially when operating near the phase envelope. The trade-off is the solving time.

Schlumberger

220


Worked Answers: Case Study 4 – ESP Selection / Design Exercise 1.

Exercise 2. 1). No. of stages (HN13000) 2). Motor HP required 3). Flowrate range for 50 – 70 Hz. 4). Flowrate for Psuction < Pbubble point

Schlumberger

58 322 1200 – 2050 sm3/d 1800 sm3/d


221

A=

B A

C

Pump operating point (flowrate & pump discharge pressure) at 50 Hz. B = Pump operating point (flowrate & pump discharge pressure) at 70 Hz. C = Pump suction pressure falls below bubble point.

Exercise 3. Production Rate (95% wcut)

Schlumberger

1480 sm3/d

222


Worked Answers: Case Study 5 – Pipeline and Facilities Exercise 1: Create PVT Model

Phase Envelope 3,400 3,200 3,000 2,800 2,600

Pressure (PSIA)

2,400 2,200 2,000 1,800 1,600 1,400 1,200 1,000 800 600 400 200 0 -50

0

50

100

150

200

250

300

350

400

Temperature (F) Baker Jardine

Exercise 2: Size Subsea Tieback and Riser

Schlumberger


223

System Outlet Pressure (psia)

Separator Pressures for Operating Liquid Rates and ID's 1,250 1,200 1,150 1,100 1,050 1,000 950 900 850 800 750 700 650 600 550 500 450 400 350 300 8,000

9,000

10,000

11,000

12,000

13,000

14,000

15,000

16,000

System Data-Liquid rate (STB/d) System Outlet Pressure : IDIAMETER=9 ins System Outlet Pressure : IDIAMETER=11 ins

1.9

System Outlet Pressure : IDIAMETER=10 ins

Errosional Velocity Ratios for Operating Liquid Rates and ID's

1.8 1.7

Erosional Velocity Ratio ( )

1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 8,000

9,000

10,000

11,000

12,000

13,000

14,000

15,000

System Data-Liquid rate (STB/d) Erosional Velocity Ratio : IDIAMETER=9 ins Erosional Velocity Ratio : IDIAMETER=11 ins

Erosional Velocity Ratio : IDIAMETER=10 ins

Schlumberger

16,000

224


Result

10”

Pipeline and Riser ID: Max. errosional velocity ratio for selected ID

0.88

Min. Separator pressure for selected ID

900 psia

Max. separator pressure for selected ID

1230 psia

Exercise 3: Check for Severe Slugging

PI-SS Number for Operating Liquid Rates and ID's 1.5

PI-SS ( )

1.4

1.3

1.2

1.1

1

8,000

9,000

10,000

11,000

12,000

13,000

14,000

15,000

System Data-Liquid rate (STB/d) PI-SS : IDIAMETER=9 ins

Result PI-SS number at riser base Flow pattern at riser base

PI-SS : IDIAMETER=10 ins

8000 STBD

0.98!! Intermittent

Schlumberger

PI-SS : IDIAMETER=11 ins

14000 STBD

1.2 Intermittent

16000 STBD

1.28 Intermittent

16,000


225

Exercise 4: Select Insulation Thickness .75" Insulation Thickness

1,800 1,700 1,600

Pressure (psia)

1,500 1,400 1,300 1,200 1,100

∆T < 2ºF Hydrates possible!

1,000 900 800 700 600

60

70

80

90

100

110

120

130

140

150

160

170

180

Temperature (F) Baker Jardine Created by User on 26/11/02 22:47:46

Schlumberger

226


1.00" Insulation Thickness

1,800 1,700

∆T = 15ºF sufficient insulation

1,600

Pressure (psia)

1,500 1,400 1,300 1,200 1,100 1,000 900 800 700 600

60

70

80

90

100

110

120

130

140

150

160

170

180

Temperature (F) Baker Jardine Created by User on 26/11/02 22:54:36

Schlumberger


227

Result Req. Insulation thickness

1.00”

Exercise 5: Size Slug Catcher

8000 STBD case:

Result

8000 STBD

14000 STBD

1/1000 slug volume (bbl)

166

187.6

Sphere generated liquid volume (bbl)

16000 STBD

226.8

485.1 448.2 436.1 = 485.1 * 1.2 = 582.1

Design volume for slug catcher (bbl)

Schlumberger

228


Worked Answers: Case Study 6 – Gas Lift Design – New Mandrel Spacing Exercise 1:

Answer Exercise 2:

Schlumberger

PIPESIM Training Manual We will choose 1.25 mmscf/d as our lift gas rate and 150 psi as the min injection gas ∆P.

Answer Exercise 3:

Schlumberger

229

230


Worked Answers: Case Study 7 – Gas Lift Design – Current Mandrel Spacing Exercise 1: -Define the Gas Lift valve system: •

In the tubing user form, in the Downhole Equipment tab, click the The Gas Lift Valve system user form will appear:

•

Select the 1st row in the user form, click on the Lift Valve Selection user form will appear.

•

Select SLB (Camco) as the manufacturer, IPO as the type, 1” as the size and BK-1 as the series. Click on

, the user form is shown below.

Schlumberger

button.

button. The Gas


• •

231

Click on Add valve to add the required valve. Add the depth of the first valve in the gas lift valve system user form.

Repeat the above steps for all the valves, the gas lift valve system user form should look as shown below:

Click on OK to exit the user form. -Perform the Deepest Injection Point operation:

Schlumberger

232


The maximum depth of injection is 4780 ft therefore we should be able to inject at the mandrel located at 4700 ft and the corresponding oil rate should be 1871 stb/d.

Schlumberger


Exercise 3:

Schlumberger

233

234


It is important to note that we are not injecting at the mandrel located at 4700 ft but at the mandrel located at 4200 ft. And the rate is not 1871 stb/d but 1708 stb/d.

Schlumberger


235

This is due to the fact that the Deepest Injection Point operation does not take into account the 15-psi pressure drop in casing pressure for each unloading valve. It is also important to notice that when designing for a current mandrel spacing the depth between valves is fixed, it is the transfer pressure that is calculated at each valve. When the transfer pressures lie to the left of the production pressure curve or the equilibrium curve, it may not be possible to transfer to the next valve.

Schlumberger

Filename: PIPESIM_course_MS_25Aug03.doc Directory: C:\download Template: C:\Documents and Settings\varredon\Application Data\Microsoft\Templates\Normal.dot Title: Field Planning Tool Case Study 2 Subject: Author: SLB Keywords: Comments: Creation Date: 10/29/2003 9:39 AM Change Number: 3 Last Saved On: 10/29/2003 9:39 AM Last Saved By: SLB Total Editing Time: 2 Minutes Last Printed On: 10/29/2003 11:16 AM As of Last Complete Printing Number of Pages: 235 Number of Words: 22,534 (approx.) Number of Characters: 128,446 (approx.)

PIPESIM Training Course

Recommend Documents