Promax Manual

ProMAX Seismic Processing and Analysis Training Manual Volume 1 copyright © 2004 by Landmark Graphics Corporation

Part No. 162382 Rev A

October 2004

© 2003 - 2004 Landmark Graphics Corporation All Rights Reserved Worldwide

This publication has been provided pursuant to an agreement containing restrictions on its use. The publication is also protected by Federal copyright law. No part of this publication may be copied or distributed, transmitted, transcribed, stored in a retrieval system, or translated into any human or computer language, in any form or by any means, electronic, magnetic, manual, or otherwise, or disclosed to third parties without the express written permission of: Landmark Graphics Corporation Building 1, Suite 200, 2101 CityWest, Houston, Texas 77042, USA P.O. Box 42806, Houston, Texas 77242, USA Phone:713-839-2000 Help desk: 713-839-2200 FAX: 713-839-2401 Internet: www.lgc.com

Trademark Notice 3DFS, 3D Drill View, 3D Drill View KM, 3DView, 3D Surveillance, Active Field Surveillance, Active Reservoir Surveillance, ADC, Advanced Data Transfer, ARIES, Asset Development Center, Asset Development Centre, Automate, Asset Performance, AssetView, Atomic Meshing, Automate, BLITZ, BLITZPAK, CasingSeat, COMPASS, Corporate Data Archiver, Corporate Data Store, Data Manager, DataStar, DBPlot, Decision Suite, Decisionarium, DecisionSpace, DecisionSpace AssetPlanner, DecisionSpace AssetView, DecisionSpace Atomic Meshing, DecisionSpace Decision Management Systems(DMS), DecisionSpace PowerGrid, DecisionSpace PowerModel, DecisionSpace PrecisionTarget, DecisionSpace Reservior, DecisionSpace TracPlanner, DecisionSpace Well Seismic Fusion, DepthTeam, DepthTeam Explorer, DepthTeam Express, DepthTeam Express3, DepthTeam Extreme, DepthTeam Interpreter, Desktop Navigator, DESKTOP-PVT, DESKTOP-VIP, DEX, DFW, DIMS, Discovery, Discovery Asset, Drill-to-the-Earth Model, Drillability Suite, Drilling Desktop, DrillModel, DSS, Dynamic Reservoir Management, Dynamic Surveillance System, EarthCube, EDM, eLandmark, Engineer’s Data Model, Engineer's Desktop, Engineer’s Link, EOS-PAK, Executive Assistant, ezFault, ezSurface, ezTracker, FastTrack, FieldWorks, FZAP!, GeoDataLoad, GeoGraphix (stylized), GeoGraphix Exploration System, GeoLink, GeoProbe, GeoProbe GF DataServer, GeoProbe Integrated, GES, GESXplorer, GMAplus, GRIDGENR, Handheld Field Operator, I2 Enterprise, iDIMS, IsoMap, Landmark, Landmark and Design, Landmark logo and Design, Landmark Decision Center, LandScape, Lattix, LeaseMap, LMK Resources, LogEdit, LogM, LogPrep, Magic Earth, MagicDesk, MagicStation, MagicVision, Make Great Decisions, MathPack, MIRA, Model Builder, MyLandmark, OpenBooks, OpenExplorer, OpenJournal, OpenSGM, OpenVision, OpenWells, OpenWire, OpenWorks, OpenWorks Well File, PAL, Parallel-VIP, PetroBank, PetroWorks, PlotView, Point Gridding Plus, Pointing Dispatcher, PostStack, PostStack ESP, PowerCalculator, PowerExplorer, PowerHub, Power Interpretation, PowerJournal, PowerModel, PowerSection, PowerView, PRIZM, PROFILE, ProMAGIC, ProMAX, ProMAX 2D, ProMAX 3D, ProMAX 3DPSDM, ProMAX MVA, ProMAX VSP, pSTAx, QUICKDIF, QUIKCDP, QUIKDIG, QUIKRAY, QUIKSHOT, QUIKVSP, RAVE, RAYMAP, RTOC, Real Freedom, Real-Time Asset Management Center, Real-Time Asset Management Centre, Real Time Knowledge Company, Real-Time Operations Center, Real Time Production Surveillance, Real Time Surveillance, RESev, ResMap, RMS, SafeStart, SCAN, SeisCube, SeisMap, SeisModel, SeisSpace, SeisVision, SeisWell, SeisWorks, SeisXchange, Sierra, Sierra (design), SigmaView, SimResults, SIVA, Spatializer, SpecDecomp, StrataAmp, StrataMap, Stratamodel, StrataSim, StratWorks, StressCheck, STRUCT, Surf & Connect, SynTool, System Start for Servers, SystemStart, SystemStart for Clients, SystemStart for Storage, T2B, TDQ, Team Workspace, TERAS, Total Drilling Performance, TOW/cs, TOW/cs The Oilfield Workstation, TracPlanner, Trend Form Gridding, Turbo Synthetics, VIP, VIP-COMP, VIP-CORE, VIP-DUAL, VIP-ENCORE, VIPEXECUTIVE, VIP-Local Grid Refinement, VIP-THERM, WavX, Web Editor, Web OpenWorks, Well Seismic Fusion, Wellbase, Wellbore Planner, Wellbore Planner Connect, WELLCAT, WELLPLAN, WellXchange, WOW, Xsection, You're in Control. Experience the difference, ZAP!, and Z-MAP Plus are trademarks, registered trademarks or service marks of Landmark Graphics Corporation or Magic Earth, Inc.

All other trademarks are the property of their respective owners. Note The information contained in this document is subject to change without notice and should not be construed as a commitment by Landmark Graphics Corporation. Landmark Graphics Corporation assumes no responsibility for any error that may appear in this manual. Some states or jurisdictions do not allow disclaimer of expressed or implied warranties in certain transactions; therefore,

Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix About The Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix How To Use The Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x Mouse Button Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x Exercise Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

Agenda. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Day 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Day 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xii Day 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Day 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv Remaining class time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

ProMAX User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 ProMAX Menu Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Building a Workspace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Flow Building and Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8 Build a Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14 Sort data by source number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14 Sort data by source and channel number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16 Sort data by CDP number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17 Display near offset section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19

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Interactivity of Trace Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1 Topics to be covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1 Trace Display Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2 Icon Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4 Using Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6 Zoom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6 Add Annotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9 Velocity Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-10 Trace Header Dump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-11 Save Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-12 Animate Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-13

Interactive Data Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14 Menu Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-18 File Pulldown Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-18 View Pulldown Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-18 Animation Pull Down Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-19 Picking Pull Down Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-20

Create and Apply a Parameter Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-21 Pick Parameter Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-21 The “Picking” icon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-23 The “Paint Brush” Icon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-25 Picking Traces to be Killed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-25 Apply the Mute and Trace Edits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-26

Exit/Stop vs. Exit Continue Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-28

Database From Full Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1 Overview of Full Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

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Extract Information from the SEGY File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Project Specifications: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Create a New Line and Run Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Complete the Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 Land 3D Geometry Spreadsheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 Enter Information in the Setup menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 Trace Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10 Automatic Bin Calculation and QC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12 CDP Bin Origin and Direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 QC, Edit and Save the CDP Binning Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17 Re-load the final CDP Binning info and Complete CDP Binning . . . . . . . . . . 3-24 Generate a Fold QC Plot and Finalize the Database. . . . . . . . . . . . . . . . . . . . . 3-25

Load Geometry to the Trace Headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28

3D Geometry from SPS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 3D Land Geometry from SPS Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Project Specifications: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Build Geometry from SPS files for Land 3D . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 Setting Project Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 Determine Primary Azimuth for Binning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 Trace Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 Spread QC after Trace Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10 Automatic Bin Calculation and QC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11 QC the Calculated Grid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13 Complete CDP Binning using the Batch CDP Binning Tool . . . . . . . . . . . . . . 4-15

Preprocessing and Elevation Statics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 Top Mute and Decon Design Gate Picking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 Isolating Analysis Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 Pick a Top Mute and Miscellaneous Time Gate. . . . . . . . . . . . . . . . . . . . . . . . . 5-4 Landmark


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Decon Test and Interactive Spectral Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7 Build a Flow to look at a power spectrum before and after decon . . . . . . . . . . . .5-7

Elevation Statics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-14 Apply Elevation Statics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-14 Datum Statics Calculation and Datum Statics Apply. . . . . . . . . . . . . . . . . . . . .5-15 Datum Statics Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-15 Comparison of Smoothed Surfaces based on CDP Smoothing . . . . . . . . . . . . .5-18 Build and Execute a Flow to Compute the N-Datum. . . . . . . . . . . . . . . . . . . . .5-18

Trace Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-21 Import First Break Picks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-21 Analyze the Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-24

Preprocessing Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-33 Build a Flow to Perform the Pre-processing . . . . . . . . . . . . . . . . . . . . . . . . . . .5-33

3D Stack and Volume Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1 3D RMS Velocity Field ASCII Import . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2 3D Parameter Table Interpolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-8 Picking a Post NMO Mute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-10 Stack 3D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-15 Run Stack3D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-16

3D Stack Volume Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-18 Inline Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-18 Crossline Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-19 Time Slice Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-21

ProMAX 3D Viewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-23 3D Viewer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-24

F-XY Decon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-30 Apply F-XY Decon to the Initial Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-30

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Display the F-XY Decon Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

3D Stack Volume Comparison Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32 3D Stack Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34 Compare Inlines from Two Stack Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . Compare Crosslines from Two Stack Volumes . . . . . . . . . . . . . . . . . . . . . . . . Compare Time Slices from Two Stack Volumes . . . . . . . . . . . . . . . . . . . . . . . Compare Difference Files from Two Stack Volumes . . . . . . . . . . . . . . . . . . .

6-34 6-36 6-39 6-39

3D Residual Statics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 Picking an Autostatics Horizon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 Calculate Residual Statics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5 QC the Picks from the Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6 Optional exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7 Display the Receiver Statics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8

Static Application and Stack Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9 Apply the Residual Statics and Reproduce the Traces: . . . . . . . . . . . . . . . . . . 7-10 Stack the Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11 Split the Flow and Output the Data for Velocity Analysis . . . . . . . . . . . . . . . . 7-12

Velocity Analysis and the Volume Viewer . . . . . . . . . . . . . . . . . . . . . . . 8-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 Velocity Analysis Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2 3D Supergather Generation and QC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4 Supergather Generation and Offset Distribution QC . . . . . . . . . . . . . . . . . . . . . 8-5

Precomputed Velocity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9 Run the Precompute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9 Velocity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-12 Velocity Analysis Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-14 Landmark


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Using the Volume Viewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-14 Velocity Analysis PD Tool: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-18

3D Dip Moveout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1 Offset Binning Parameter QC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-2 Examine the Offset Binning Problem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-2 Offset Binning Parameter Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-5

DMO to Gathers 3D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-12 DMO Stack 3D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-17

CDP Taper on Stack Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-1 CDP Taper Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-2 Execution of CDP Taper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-4 Generating QC Plots of the Taper Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-6 QC Plots from DBTools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-6 Try other values for TOPTAPER and BOTTAPER. . . . . . . . . . . . . . . . . . . . . .10-6

3D Velocity Viewer/Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-1 3D Velocity Viewer/Editor Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-2 Icon Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-2 3D Table Triangulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4

3D Velocity Viewer/Editor Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-5 Select the 3D Velocity Viewer Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-5

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Edit and Smooth the RMS Velocity for FK Migration. . . . . . . . . . . . . . . . . . . 11-6 Icon Bar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-7 Velocity Field Gridding and Smoothing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-9 Convert to Interval Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-10

Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-1 Topics covered in this chapter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-1 3D Migration Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-2 Stolt 3D Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase Shift Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PSPC 3D Depth Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Explicit FD 3D Time Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Explicit FD 3D Depth Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12-3 12-3 12-3 12-3 12-4

Re-datum Velocities to Flat Datum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-5 Re-datum the Interval Velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-5

3D Migration Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-6

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Contents

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Preface About The Manual This two volume manual is intended to accompany the instruction given during the standard ProMAX Seismic Processing and Analysis course. Because of the power and flexibility of ProMAX, it is unreasonable to attempt to cover all possible features and applications in this manual. Instead, we try to provide key examples and descriptions, using exercises which are directed toward common uses of the system. The amount of material in the manuals exceeds what can be covered in a typical training course. This is intentional as it allows the instructor to tailor each class to the needs of the students by selecting the appropriate material. After the class, you will find the manuals useful as a supplement to the online user manual. How To Use The Manual This manual is divided into chapters that discuss the key aspects of the ProMAX system. In general, chapters conform to the following outline: •

Introduction: A brief discussion of the important points of the topic and exercise(s) contained within the topic.

•

Topics Covered in Chapter: Brief list of skills or processes in the order that they are covered in the exercise.

•

Topic Description: More detail about the individual skills or processes covered in the chapter.

•

Exercise: Details pertaining to each skill in an exercise, along with diagrams and explanations. Examples and diagrams will assist you during the course by minimizing note taking requirements and providing guidance through specific exercises.

This format allows you to glance at the topic description to either quickly reference an implementation or simply as a means of refreshing your memory on a previously covered topic. If you need more information, see the Exercise sections of each topic.

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Preface

Conventions Mouse Button Help This manual does not refer to using mouse buttons unless they are specific to an operation. MB1 is used for most selections. The mouse buttons are numbered from left to right so: MB1 refers to an operation using the left mouse button. MB2 is the middle mouse button. MB3 is the right mouse button. Actions that can be applied to any mouse button include: •

Click: Briefly depress the mouse button.

•

Double Click: Quickly depress the mouse button twice.

•

Shift-Click: Hold the shift key while depressing the mouse button.

•

Drag: Hold down the mouse button while moving the mouse.

Mouse buttons will not work properly if either Caps Lock or Nums Lock are on. Exercise Organization Each exercise consists of a series of steps that will build a flow, help with parameter selection, execute the flow, and analyze the results. Many of the steps give a detailed explanation of how to correctly pick parameters or use the functionality of interactive processes. The editing flow examples list key parameters for each process of the exercise. As you progress through the exercises, familiar parameters will not always be listed in the flow example. The exercises are organized such that your dataset is used throughout the training session. Carefully follow the instructor’s direction when assigning geometry and checking the results of your flow. An improperly generated dataset or database may cause a subsequent exercise to fail.

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Agenda Day 1 Introductions, Course Outline, and Miscellaneous Topics ProMAX User Interface • • •

Initial Demonstration Flowbuilding Exercise Data Sorting

Interactivity of Trace Display • • •

Demonstration and description Interactive Data Access Parameter Table Picking

Full extraction geometry • • •

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Extract information from SEGY file Bin traces and complete the database Load Geometry to the trace headers


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Chapter Agenda

Day 2 3D SPS Geometry • •

Import SPS information Bin traces and complete database

Preprocessing and Elev statics • • • • •

Pick top mute and deconvolution design gate Deconvolution tests and Interactive Spectral Analysis Elevation Statics Trace kills using trace statistics Apply pre-processing to the shots

Stack and Volume Comparison • • • • • • •

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Import initial velocity file Pick a post NMO mute Stack 3D 3D Stack Volume Displays ProMAX 3D Viewer F-XY Decon 3D Stack Volume Comparison


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Chapter Agenda

Day 3 Residual statics • • •

Picking an autostatics Horizon Calculate Residual Statics Static application and stack comparision

• •

3D Supergather formation and QC Precomputed Velocity analysis • Run the Precompute • Velocity Analysis • Using the Volume Viewer

• • •

Offset Binning and parameter QC DMO to Gathers 3D DMO Stack 3D

Velocity Analysis

DMO

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Chapter Agenda

Day 4 CDP Taper • •

Execution of CDP Taper QC plots of the taper values

• •

3D Velocity Viewer/Editor Overview 3D Velocity Viewer/Editor Execution

• • •

3D Migration Overview Re-datum velocities to flat datum 3D Migration Exercise

Velocity Prep

Migration

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Chapter Agenda

Remaining class time For the remaining class time, consult with the instructor and choose from the following sections in Volume 2:

2D Marine workflow • • • • • • •

Manual Geometry Parameter Testing Preprocessing Brute Stack Velocity Analysis Final Stack Migration

4 hours to complete

2D Land workflow • • • • • • •

Geometry from Full Extraction Parameter Testing with Conditional Processing FK Filtering and Analysis Spectral Analysis Elevation Static Corections Velocity Field ASCII Import Stack

4 hours to complete

Appendix A: Additional 2D Geometry • • • • •

Geometry Core Path Overview Details of the Geometry Programs Pre-Geometry Database Initialization Inline Geometry Header Load after Pre-Initialization Geometry from Full Extraction

2 hours to complete

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Chapter Agenda

Appendix B: Manual Land Geometry • • • • • • •

Geometry Assignment Map Land Geometry View Shot Gathers Load Geometry in Spreadsheet and Database View Database Attributes Load Geometry to the Trace Headers Graphical Geometry QC

2 hours to complete

Appendix C: 3D Marine Geometry from UKOOA 2 hours to complete

Appendix D: 3D Land Swath Geometry 2 hours

Appendix E: Archival Methods 30 minutes

Appendix F: Demultiple Techniques • • • •

Radon Analysis and Filter Radon Velocity Filter Eigenvector (KLT) Filtering F-K Multiple Attenuation

2 hours

Appendix G: Supergather Formation 30 minutes

Appendix H: Apply User Statics 1 hour

Appendix I: Plotting 30 minutes

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Chapter Agenda

Appendix J: 2D Neural Network Firstbreak Picking 1 hour

Appendix K: Source Receiver Geometry Check Must first complete Appendix J: Neural Network Firstbreak Picking 30 Minutes

Appendix L: 2D Refraction Statics Must first complete Elevation Statics chapter in the 2D Land workflow 1 hour

Appendix M: Parallel Processing in ProMAX Lecture only 30 Minutes

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Chapter Agenda

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Chapter 1

ProMAX User Interface This chapter will get you started processing with ProMAX. You will learn how to set up a work space with the ProMAX User Interface, and then build and execute data processing flows.

Topics covered in this chapter:

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o

ProMAX Menu Map

o

Getting Started

o

Building a Workspace

o

Flow Building and Execution

o

Data Sorting


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Chapter 1: ProMAX User Interface

ProMAX Menu Map

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Getting Started ProMAX is built upon a three level organizational model referred to as Area/Line/Flow. When entering ProMAX for the first time, you will build your own Area/Line/Flow workspace. As you add your own Area, you may want to name it with reference to a geographic area that indicates where the data were collected, such as “Onshore Texas”, or use your name, such as “daves area”. Line is a subdirectory of Area which contains a list of 2D lines from an area, or the name of a 3D survey. After choosing a line from the Line menu or adding a new line, the Flow window will appear. Name your flows according to the processing taking place, such as “brute stack”. For this course, we will also use a number, for example "01: Display shots". Look at the Menu Map figure on the previous page. This figure refers to the menus we have just discussed, as well as other menus you will use to access your datasets, database, and parameter tables. Building a Workspace In this exercise, you will build a workspace and look at some of the functionality available within the user interface. Initiating a ProMAX session is done in a variety of ways. Typically your system administrator will create a start-up script or make a UNIX alias, and set certain variables within your shell start-up script to make this easy. Starting ProMAX will not be discussed in this Essentials class. You will use a start-up script that has already been built. 1. Type promax A product name window appears, followed by the Area menu that displays a list of all available Areas. Along the top of this window you will find the version number of the User Interface, the machine identification code, hostname, and license ID. The Areas are described by a user specified name, and a UNIX name. The UNIX name is a parsed version of the name you selected for the area. Capital letters, most punctuation, and spaces are removed in the parsing routine. This parsed name is the name of the actual UNIX directory. Other information is also listed, such as owner, date and the number of lines in each Area.

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Available areas

Active Command

Global Options

Area Menu Exit Promax Processing Queues Window

Mouse Button Help

Configuration Options

Job Notification and Control

Area Menu The black horizontal band below the menu displays mouse button help. Mouse button help describes the possible actions at the current location of the cursor, and gives brief parameter information during the flow building process. Below the mouse button help line are options to Exit ProMAX, configure the queues and user interface, as well as check on the status of jobs. •

1-4

Config: Brings up settings which control how lists of Areas, Lines, Flows, Datasets, Parameter tables and Headers are sorted. Also controls nice values for running flows, the number of copies of flow output, where ProMAX UI restarts after exit and


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popup behavior. Lastly, it allows you to specify the attributes dsplayed for Areas and Lines. •

Option: Brings up settings for debugging, compression, use of dataset headers for sorting, and locations of data, scratch space and the configuration file.

•

Queue: Allows user to control batch processing queues.

•

Exit: Will exit the User Interface, prompts to save if there is an unsaved flow.

•

Notification: Gives information about jobs, and allows user to check job status.

The list of options running across the top of this menu: Select, Add, Delete, Rename, and Permission are called global options. To use these, you must first select the command, then select the Area name that you want the command to apply to. The Copy command works differently by providing popup menus to choose an Area to copy from. 2. Select Add from the Area Menu with MB1. At this point you are building your work space. Adding an Area creates a UNIX directory. 3. Before moving the mouse, enter an Area name Use your name for the area name. For example, “Mary’s area”. 4. Press return, or move the mouse to register your selection. You can control whether moving the mouse registers the selection, or if you need to press return in the Config popup. Set the Popups remain after mouse leaves option to yes or no. The Line Menu appears with the same global options to choose from as the Area Menu.

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1-5


5. Add a Line using the same steps as you did for adding an Area. Name the line “Intro Line”

Area Name

Global Options

Available Seismic Lines

Line Menu

Line Menu

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The Flow window appears with the following new global options:

6.

Access Datasets

•

Datasets: Lists all your datasets for that particular line.

•

Database: Allows you to view your Ordered Parameter Files.

•

Tables: Allows you to view various Parameter Table Menus.

•

Product: Changes from ProMAX 2D to ProMAX 3D or VSP.

Add a Flow and name it “01: Display Shots”.

Access Database

Access Parameter Tables

Change Products

Available Flows

Flows Menu

Flow Menu

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1-7


Flow Building and Execution Now it is time to build a flow, and process data. In order to perform this you will need to tell ProMAX which processes you want to invoke, as well as provide specific details for each of these steps. Finally, there are different options available for executing a flow. Build a Flow Upon completion of the previous exercise, you are in the ProMAX flow building menu (see below). From here, you will construct flows by choosing processes and selecting the necessary parameter information. Once the flow is ready, you will execute it and view the results. 1. Look at the flow building menu.

Editable Flow

Parameter Specification

Available Processes

Edit Flow Menu 1-8


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The screen is split into two sides: a list of processes on the right and a blank tablet below the global options on the left. To build a flow, you will select from the processes on the right and add them to the blank tablet on the left. 2. Move your cursor into different areas of the display, such as into the processes list, the blank tablet and the global options. Notice that the mouse button help is sensitive to the current cursor location. 3. Global Options for flow editing: •

Add: This is the default. When highlighted in blue, a process can be selected from the list of processes and added to the flow.

•

Delete: When selected with MB1, the highlighted process is removed from the flow. This process is actually stored in a new kill buffer. Selecting Delete with MB2 appends a newly deleted process to the existing kill buffer. MB3 is used to insert (paste) the contents of this buffer into the current flow. The memory of the buffer is maintained even after exiting a flow menu, so the contents may be cut and pasted from one flow to another.

•

Execute: When selected, the job is executed.

•

There are two methods available to execute a flow using the Trace Display process:

MB1 and MB2 will execute the flow interactively. The mouse button help explaining the difference between MB1 and 2 does not apply to the Trace Display process. Either button will allow the display to immediately take over the monitor for display. MB3 indicates Execute via Queue. This option enables the use of the two types of batch queues. When using MB3, a new menu pops up allowing the use of either the general batch queues or the small job batch queues. In order for this option to work, your system administrator must enable the queues whenProMAX 2D was installed.

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•

View: Accesses the view (job.output) file. This file includes important job information such as error statements.

•

Exit: Leaves the edit flow menu, and returns you to the flow listing menu.


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4. Move your cursor into the Data Input/Output portion of the processes list, and select the process “Disk Data Input” with MB1. You have just added your first process to a flow. The list of available processes is very long. It is ordered from top to bottom in a general processing sequence with I/O processes at the top and poststack migration tools further down on the list. There is a scroll bar to help you view the list. There are also options available to hide processes in the secondary, or More list. By doing this, you can customize the list to only display the processes you use most often. 5. In the Data Input / Output category, click MB1 on the word “MORE”. Notice that a popup appears containing a list of secondary processes. 6. Move the “SS Phoenix Output” process to the secondary list, and make sure the procedure worked correctly by viewing the secondary list again. To move a processes to the secondary list, click MB3 on the process name (notice the mouse button help). You can move a process from the secondary to primary list with the same procedure. There is also a text search to help you find specific processes. 7. Move your cursor back into the processes list (but not on a category heading),type “gain” and press return. The following appears:

This acts as a text search, and displays all processes that contain the word "gain." Add the process Automatic Gain Control by selecting the process name with MB1.

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8. Finish building the following flow by adding the “Trace Display” process to your flow. Editing Flow: Add

01: Display Shots

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?: -----------------------------Yes Select dataset: --------------------------------------Area: 2d-tutorials ----------------------------------Line: Wave Equation Multiple Reject --------------------------------------------Dataset: Shots-w/ geometry Trace Read Option: ---------------------------------------------Get All Read the data multiple times?: ------------------------------------No Process trace headers only?: --------------------------------------No Override input data’s sample interval?: ------------------------No

Automatic Gain Control Application mode: ------------------------------------------------Apply Type of AGC scalar: --------------------------------------------MEAN AGC operator length: --------------------------------------------1500 BASIS for scalar application: ------------------------------Centered Exclude hard zeroes?: ----------------------------------------------Yes Robust Scaling?: -----------------------------------------------------No

Trace Display ----Default all parameters for this process---9. Select Disk Data Input parameters. Select Disk Data Input with MB2 to bring up the parameter selection window. To view the helpfile for a process, select the red highlighted question mark. 10. Select Yes for the “Read data from other lines/surveys?” parameter. For the introductory lessons we will read data from the tutorial line. 11. Select Invalid for the “Select dataset” parameter. Follow the instructor’s directions for the exact path to the dataset. After you select the dataset you will be returned to the flow editing menu. Landmark


1-11


Default the rest of the parameters in this menu. 12. Select Automatic Gain Control with MB2. You can now modify parameters for AGC. Select Apply for the Application mode. By clicking on the parameter, a popup menu appears for making a selection from the menu. Help text appears for each of the associated choices in the popup menu. Move your mouse out of the popup window to retain the default. 13. Set the AGC operator length to 1500ms. To change this value simply place your cursor on the old value, and type in the number 1500. This example is called a Type-In parameter. Type in a value to replace the defaulted or existing value. The mouse help will always read, “MB1 Enter, MB2 Edit”. Clicking MB1 will clear the default and let you enter the new parameter. Clicking MB2 will let you edit the existing default value. 14. Select Trace Display parameters. For now, do not change any of the values. We will discuss many of these options in the next chapter. At that point, you will have the opportunity to test and explore the various options.

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15. Run the flow by clicking on the global command Execute with MB1 or MB2. A new Trace Display window appears on the screen. Ten icons appear in a column to the left of the traces, and pulldown menus appear above the traces. There is a detailed discussion of these in the next chapter.

Next Screen Icon

16. Select the Next Screen icon with MB1. This takes you to the next shot. Repeat 2-3 times. 17. Select File

Exit/Stop Flow.

This interrupts the job and brings you back to the flow editing menu.

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Sorting Your first look at the data was the first shot with all channels. After clicking the Next Ensemble icon, you saw the next shot. What if you wanted to look at every other shot? What if you only wanted to look at channels 1 through 60? What if you wanted to sort the data to CDP and then display. All these options and more are available in Disk Data Input. Sort data by source number 1. Edit your flow named “01: Display Shots”. Editing Flow: 01: Display Shots Add

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?-------------------------------Yes Select dataset: --------------------------------------Area: 2d-tutorials ---------------------------------Line: Wave Equation Multiple Reject ---------------------------------Dataset: Shots-w/ geometry Trace Read Option--------------------------------------------------Sort Interactive Data Access?: ------------------------------------------No Select primary trace header entry------------------------SOURCE Select secondary trace header entry ----------------------- NONE Sort order for dataset ----------------------------------------------1,3/ Presort in memory or on disk?: ----------------------------Memory Read the data multiple times?: ------------------------------------No Process trace headers only?: --------------------------------------No Override input data’s sample interval?: ------------------------No

Automatic Gain Control ----Use the same parameters as before----

Trace Display ----Default all parameters for this process---2. Open the Disk Data Input Menu and click where the menu reads Get All for Trace Read Option.

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This toggles the read option to Sort, and the menu will automatically add several new options: •

Select Primary trace header entry: Allows you to specify a group of ensembles or traces to read, or sort the data to a different order. Virtually all sorting within ProMAX is done on input. This allows a user to easily change domains without running a separate, time consuming flow. An ensemble in ProMAX is any logical grouping of traces, such as a shot record, or a CDP gather.

•

Select Secondary trace header entry: Allows you to re-order, and choose which traces you want to read within each ensemble.

•

Sort order for dataset: Allows you to specify an order, or restrict the amount of data brought read.

•

Interactive Data Access: Allows you to move forward and backward throught the data after it is displayed, as well as change the values for primary and secondary sort order to jump to a new location. Also allows you to select an ensemble to display from the database.

3. Select SOURCE for the primary sort order, this will read in shot ordered ensembles. 4. Leave the secondary sort set to NONE, this means that no sorting of traces within ensembles will be performed. 5. Select Sort order for dataset. An Emacs Widget Window appears for specifying input traces. A format and example are given at the bottom of this window. 6. In the Widget Window delete the default values, and type 1, 3/. This specifies that only SOURCE numbers 1 and 3 will be read into the flow. 7. Move your cursor out of the Widget Window. 8. Select Execute. The first shot displayed is Live Source Number 1.

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1-15


9. Select the Next Screen icon. This will be Live Source Number 3. When the last source is displayed, the Next Screen icon becomes Exit/Stop Flow. inactive. To exit this display, select File Sort data by source and channel number Lets make the exercise slightly more complicated, and display every tenth shot, limiting the number of channels to 1-60. 1. Edit your previous flow. Editing Flow: 01: Display Shots Add

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?-------------------------------Yes Select dataset: --------------------------------------Area: 2d-tutorials ---------------------------------Line: Wave Equation Multiple Reject ----------------------------------Dataset: Shots-w/ geometry Trace Read Option--------------------------------------------------Sort Interactive Data Access?: ------------------------------------------No Select primary trace header entry-------------------------SOURCE Select secondary trace header entry ---------------------- CHAN Sort order for dataset -------------------------------1-101(10):1-60/

Automatic Gain Control Trace Display 2. Select CHAN for the secondary trace header entry. This will allow you to sort each SOURCE ensemble by channel number, and also limit the number of channels to be processed. 3. Change the Sort order for dataset to 1-101(10):1-60.

1-16

•

1-101 selects the SOURCE range to be processed.

•

(10) selects every tenth SOURCE within the defined range.


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•

: separates the primary sort order from the secondary sort order.

•

1-60 selects the first 60 CHAN (channels) within each SOURCE.

Note If you only select a primary sort key, then only one range of values is allowed in the sort order for dataset. If you select both a primary and a secondary sort key, then two ranges of values, separated by a colon, are necessary in the sort order. This is a common area for new ProMAX users to make mistakes.

4. Execute the flow. You will see the first shot and all subsequent shots display with only the first 60 channels. 5. Select the Next Screen icon to see additional shots. 6. Move your cursor into the trace display area. Notice that the mouse button help gives a listing of the current CHAN and SOURCE. Trace Display will always give you a listing of the values for the current Secondary and Primary sort keys. 7. Select File

Exit/Stop Flow when finished.

Sort data by CDP number The dataset that we have been reading, is stored on disk in shot order. Both of the previous exercises maintained the shot ordering, and specified the shot gathers to be displayed. In this exercise you will actually read in the data as CDP gathers. This uses the other side of sorting, which is to actually change the type of ensemble being processed. Recall that the primary trace header entry specifies the type of ensemble to build, and also the range of that ensemble to read. The secondary sort key allows you to sort and select the traces within each ensemble.

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1. Edit your previous flow. Editing Flow: 01: Display Shots Add

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?-------------------------------Yes Select dataset: --------------------------------------Area: 2d-tutorials ---------------------------------Line: Wave Equation Multiple Reject ---------------------------------Dataset: Shots-w/ geometry Trace Read Option--------------------------------------------------Sort Interactive Data Access?: -------------------------------------------No Select primary trace header entry-------------------------------CDP Select secondary trace header entry ----------------------OFFSET Sort order for dataset ---------------------------------500-600(25):*/

Automatic Gain Control Trace Display 2. Select CDP for the Primary trace header entry. This tells the program to build CDP gathers from the input dataset. 3. Select OFFSET for the secondary trace header entry. This tells the program to order the traces within each CDP gather by the OFFSET header. 4. Set the sort order for dataset to 500-600(25):*/. •

500-600(25) This select every 25th CDP between 500, and 600.

•

* This is a wildcard that tells the program to read in all OFFSET ranges.

5. Execute the flow. 6. Notice that we have now displayed a CDP gather, even though the input dataset is stored on disk as shot gathers. 7. Move your cursor into the trace display area, and confirm that the displayed gather has Primary and Secondary sorts of CDP and OFFSET. 8. Select File

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Exit/Stop Flow when finished


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Display near offset section Using the sorting capabilities within Disk Data Input, you can easily display a near offset section by selecting the first channel on each shot. A near offset section will give you a broader overview of what the geology for your line looks like. 1. Edit your previous flow. Editing Flow: 01: Display Shots Add

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?-------------------------------Yes Select dataset: --------------------------------------Area: 2d-tutorials ---------------------------------Line: Wave Equation Multiple Reject ----------------------------------Dataset: Shots-w/ geometry Trace Read Option--------------------------------------------------Sort Interactive Data Access?: -------------------------------------------No Select primary trace header entry-----------------------------CHAN Select secondary trace header entry ----------------------SOURCE Sort order for dataset ----------------------------------------------*:*/

Automatic Gain Control Trace Display 2. Change the primary trace header entry to CHAN (which is roughly equivalent to offset). 3. Set the secondary trace header entry to SOURCE. 4. Set the sort order for dataset to *:*/. This will select all channels for all shots starting with channel number 1. 5. Select File

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Exit/Stop Flow when finished.


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Chapter 2

Interactivity of Trace Display Trace Display provides general trace display and analysis capabilities. In addition, it allows for interactive definition of parameter tables. Interaction with the data is accomplished using a series of icons and pulldown menus presented upon execution of a flow with Trace Display. Icon or menu choices allow you the ability to: • • •

Obtain information about the traces in the display window. Modify the presentation. Define processing parameter information.

Topics to be covered in this chapter:

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o

Trace Display Window

o

Icon Bar

o

Details of how to use the Icons

o

Interactive Data Access

o

Menu Bar

o

Create and Apply a Parameter Table


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Chapter 2: Interactivity of Trace Display

Trace Display Window 1. In the previous section we built a flow to display some shot data. Execute that flow again with the following parameters: Editing Flow: Add

01: Display Shots

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?: -----------------------------Yes Select dataset: --------------------------------------Area: 2d-tutorials ----------- ----------------------Line: Wave Equation Multiple Reject ----------------------------------Dataset: Shots-w/ geometry Trace Read Option: -------------------------------------------------Sort Interactive Data Access?: ------------------------------------------Yes Select primary trace header entry--------------------------SOURCE Select secondary trace header entry -------------------------- CHAN Sort order list for dataset: -----------------------------------------*:*/

Automatic Gain Control Application mode: ------------------------------------------------Apply Type of AGC scalar: ---------------------------------------------MEAN AGC operator length: ---------------------------------------------1500 BASIS for scalar application: -------------------------------Centered Exclude hard zeroes?: ----------------------------------------------Yes Robust Scaling?: -----------------------------------------------------No

Trace Display ----Default all parameters for this process----

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You will get the following display: Icon Bar Menu Bar

Mouse help

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Interactive Data Access

Data display


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Icon Bar Following is a brief description of the Trace Display icons, located in the icon bar:

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•

Next Ensemble: Show the next ensemble. When there is no more data in the flow, the icon will turn gray and become inactive.

•

Previous Ensemble: Shows the previous ensemble. Is not active if the user does not specify Interactive Data Access in the input flow, or if the first ensemble in the sort order is currently displayed.

•

Rewind: Shows the first ensemble in the sort order. Is not active if the user does not specify Interactive Data Access in the input flow, or if the first ensemble in the sort order is currently displayed.

•

Save Image: Save the current screen image. Annotation and picked events are saved with the trace data, to be viewed later.

•

Animation: Brings up the Animation dialog box to review the saved images. This button is active only when there are at least two saved screen images. You have the option to cycle through the selected screens at a chosen rate. These are just screen images, you cannot edit parameter files using the saved image.

•

Paint Brush: Use this tool to apply picked Trace Kills, Reversals, and Mutes to the display. This tool is only active when you are picking a parameter table. The paintbrush tool is a toggle button, select once to apply the active tables, select again to undo.


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•

Zoom Tool: Click and drag using MB1 to select an area to zoom. If you release MB1 outside the window, the zoom operation is canceled. If you just click MB1 without dragging, this tool will unzoom. You can use the zoom tool in the horizontal or vertical axis area to zoom in one direction only

•

Annotation Tool: When active, you can add, change, and delete text annotation in the trace and header plot areas. For adding text, activate the icon, then click MB1 where you want the text to appear. For changing text, the pointer changes to a circle when it is over existing text annotation, move by dragging the text with MB1, delete by clicking MB2, and edit the text or annotation color with MB3.

•

Velocity Tool: Displays linear or hyperbolic velocities. For a linear velocity, click MB1 at one end of a waveform and drag the red vector out along the event. A velocity is displayed at the bottom of the screen. Use MB2 to display a hyperbolic velocity by anchoring the cursor at the approximate zero offset position of the displayed shot or CDP. Position the red line along the event and read the velocity at the bottom. New events can be measured with either velocity option by reclicking the mouse on a new reflector to reanchor the starting point. Velocities can be labeled by using MB3 on the current velocity. Geometry must be assigned to successfully use this icon.

•

Header Tool: Displays detailed information about trace headers and their values for each individual trace. Activate the icon, and click MB1 on any trace to call up the header template. If the header template is in the way of the traces being viewed, you can move the template by dragging the window. To remove the template deactivate the header icon, or activate any other icon.


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Using Icons In this section we will review the functionality of the Icons in Trace Display Zoom

There are three ways to zoom in Trace Display 1. Select a rectangular area.

Press and hold MB1 to define the first corner of the zoom window. Continue to hold the button and drag the cursor to the other corner. Release the Mouse button and the display will zoom 2. A single MB1 click will unzoom the display.

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3. Select a time range.

Press and hold MB1 in the column of numbers to define the start time Continue to hold the button and drag the cursor to the maximum time. Release the Mouse button and the display will zoom 4. A single MB1 click will unzoom the display.

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5. Select a range of traces.

Press and hold MB1 in the row of numbers to define the start trace Continue to hold the button and drag the cursor to the maximum trace. Release the Mouse button and the display will zoom 6. A single MB1 click will unzoom the display

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Add Annotation Text annotation can be added anywhere on the display, a useful feature for screen dumps to help identify specific features present on the display. Text may be added, moved (in position on the display), and/or edited using the appropriate mouse button as described at the bottom of the display in the mouse button help area.

Click MB1 anywhere on the screen and the "Edit Text" window appears. Type in some text and press the OK button. The text will appear on the display where you clicked. You may move, delete or edit this text by placing the cursor on the text. You may add another text label by clicking somewhere else on the display. The size of the text can be controlled as an X-resource by editing the appropriated X-resources file.

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Velocity Measurement With the dx/dt analysis feature you can measure the apparent velocity of linear or hyperbolic events that appear on the display. This feature will only work if the trace offset values in the headers exist and are accurate.

Click MB1 on a linear event of interest. Move the mouse away from the point where you clicked A red line should appear with velocity tracking at the bottom of the display. Press MB3 at the end of the line and the velocity will be annotated near the line. Hyperbolic events can be measured by using MB2 to initiate the line instead of MB1

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Trace Header Dump You can get a listing of all of the existing trace headers and their values for any given trace by using this icon.

Select any trace with MB1 and the trace header listing will appear in a separate window. You can continue by selecting a different trace. You can remove the window by clicking on the icon again. You may also find resizing and moving the windows to be useful.

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Save Screen This icon saves the current screen image as an XWD file in memory. These screens can be recalled from memory and then can be reviewed in different sequences.

By default, a screen is saved every time a different ensemble is displayed. If you change the display of a current ensemble and want to save an image you must press the Save Screen icon. Save three or four screens by either displaying a different ensemble, or by changing the display (zoom, annotation, etc.) and manually saving the screen.

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Animate Screens After you save at least two screens, the Animation Icon becomes active.

With the Animation window active you can review the saved screens. You may elect to view them circularly, one at time in sequence, or compare two of the saved screens. The speed of the circulation can also be controlled by the Speed Slide bar. The speed can be changed as the screens are swapping.

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Interactive Data Access ProMAX has a very flexible set of options for interactive data access. These interacitve data access options are available in most of the display tools such as Trace Display, and Velocity Analysis. Interactive data access is only active when it has been specified in data input step to the display. There are three options for interactive data access: •

Sequentially move forward and backward, or jump to the first ensemble using the Next Ensemble, Previous Ensemble, and Rewind icons within the display tool.

•

Use the Interactive Data Access window to change to sort order, or jump to a specific range of ensembles.

•

Choose a set of ensembles in the database and send them to a display tool.

The first two methods will be discussed here. The database selection method will be covered in a later chapter.

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1. Sequentially move forward and backward several times using the Next Ensemble and Previous Ensemble icons. Next

Previous

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2. Jump back to the first ensemble using the rewind icon.

Rewind to First Ensemble

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3. Type a range of ensembles to display in the box supplied, and press the Send Sort Order List button. 4. Notice that the Primary, Secondary, and Tertiary sorts are displayed for reference only, you cannot change to sort order here. Also notice that you can select a previous sort list from the middle box, or select a previously saved sort list from the file menu.

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Menu Bar

File Pulldown Menu File has seven options available in a pulldown menu. You can save your picks, make a hardcopy plot, move to next screen, previous screen or rewind, or exit Trace Display. You have two choices when you exit. You can exit and stop the flow, or you can exit and let the flow continue without Trace Display. Note: Use caution when using the stop option. For example, assume that you have a flow that contains Disk Data Input to read in ten ensembles followed by Disk Data Output and Trace Display. If you execute this flow and use the Exit/Stop Flow option after viewing the first five ensembles, then only the five ensembles that you viewed will be stored in the output dataset as opposed to writing out ten ensembles. If you use the Exit/Continue Flow option instead, then all ten ensembles will be written out.

View Pulldown Menu View has six options in a pulldown menu. You can control the trace display, the trace scaling, and trace annotation parameters. You can also choose to plot a trace header above the trace data, edit the color map used for color displays or toggle the color bar on and off. Common changes would be to change the Amplitude Scaling Factor from 1 to other values, and to change the display mode from WT/VAR to Variable Density using a greyscale. Adding Header plots of various header words is also commonly done. For pre-stack data you may elect to plot the offset above the traces and for stack data you may want to plot the stack fold above the section. You may also elect to change the numbers plotted above the traces. For example you may want to look at the FFID numbers and the offsets. The best way to learn these features is to play with them and see what happens. 2-18


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Watch the difference between the Apply and OK buttons. The Apply button will make the changes but the selection window will remain. The OK button will make the changes and dismiss the window.

Animation Pull Down Menu The Animation menu allows you to save screens, or display previously saved screens in any order and at different swap speeds. The animation tool pictured below, is used to display previously saved screens. This is identical to the functionality provided by the Save Screens and Animate Screens icons.

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Picking Pull Down Menu Picking allows you to interactively open and add information to one or more parameter tables. These parameter tables allow you to save information about which picked traces you’d like to kill or reverse. Also, you can pick any kind of mute, horizons, gates, or autostatics horizons. Other options allow you to edit database or header values. We will look at this option in the next section. Once you have selected a parameter table for your picks, a new icon will appear in the icon bar.

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Create and Apply a Parameter Table Parameter tables are generated when you interactively define lists or tables of information. These files are stored in binary format and are intended for use in subsequent processing flows. The interactivity of Trace Display allows you to generate these tables, while viewing the data. You may also QC the interpolation of values from one shot, or CDP to another for space variant parameter tables such as mute functions. Pick Parameter Tables In this exercise, you will pick a top mute and some example trace edits. Other parameter tables may be picked in a similar fashion. 1. Edit your flow named “01: Display Shots”. Editing Flow: 01: Display shots Add

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?-------------------------------Yes Select dataset---------------------------------------Shots- w/ geometry Trace Read Option--------------------------------------------------Sort Interactive Data Access?: -------------------------------------------No Select primary trace header entry--------------------------SOURCE Select secondary trace header entry -------------------------- NONE Sort order for dataset ----------------------------------------1,88,176/ ----Default the remaining parameters-----

Automatic Gain Control ----Use same parameters as before----

Trace Display Number of ENSEMBLES (line segments) / screen -----------------3 ----Default all remaining parameters for this process--2. Select to read the first, last, and middle shot gathers on the line (Sources 1,88,176).

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3. Set the number of ensembles to display per screen to 3. 4. Select Execute. The interactive Trace Display window appears.

3 Example shots for Parameter Table Picking 5. Select Picking Pick Top mute. Another window appears for selecting a previous mute parameter file or creating a new file.

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When you create a new file, another window appears listing trace headers to choose the secondary key from.

In this case, an appropriate key for Muting traces would be AOFFSET, allowing selection of the mute within each shot record based on Times that are interpolated as a function of absolute value of offset. Depending upon the parameter table you are picking, the most appropriate secondary header should appear at the top of the list. The “Picking” icon •

This appears when one or more pick objects from the Picking menu are selected. A small window with the file name will appear on the right hand side of the screen. This means the table is open and ready to be edited. When active, click with MB1 to pick a point on a trace or click and drag to pick a range of traces. When the mouse is over a picked point, the pointer shape changes into a circle. Click and drag using MB1 to move a picked point. Use MB2 to select a single point to delete, or click and drag over a range of points to delete them. To select traces from the next shot, use the Next Ensemble icon. The created table remains open, and waits for more picks to be added to the file. Some parameters require a top and a bottom pick, such as a surgical mute. Once you have picked the top of the mute zone, depress MB3 anywhere inside the trace portion of Trace Display. A new menu appears allowing you to pick an associated layer (New Layer). Some of the other options allow you to snap your pick to the nearest amplitude peak, trough or zero crossing.

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6. Pick a mute. Pick a few points (3 to 6) on the first shot to define a top mute to remove the refraction energy. Selected points will be connected and interpolated as well as extrapolated. Your mute should look similar the following:

Picking a Mute 7. Click MB3 in the display field and choose Project from the popup menu to display the projection of your picks on all offsets and to the other shots in the display.

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8. Pick a different mute on the last shot and project again. Watch how the projected mute on the center shot is interpolated based on the first and last shots. The “Paint Brush” Icon The Paint Brush can be used to visually show the effect of applying the mute. 9. Select the Paint Brush icon. You can toggle the mute on and off with the Paint Brush Icon. Edit the mute if you are not happy. Remember you can only edit picks when the picking icon is highlighted. Picking Traces to be Killed 10. Select Picking

Kill Traces.

You will be prompted to enter a descriptive name for this list of traces to be killed followed by a secondary header selection. Use a name similar to “Traces to be killed” sorted by Channel number. A second parameter table is now listed in the Parameter table selection window.

11. Using MB1 select some traces to be killed (use your imagination). MB2 can be used to remove previously selected traces from the list. The traces to be killed will be marked with at Red line. 12. Select File Exit/Stop Flow. When you choose to exit, you are prompted to save the picks you have just made. The picks are saved in parameter tables which can be used later in processing.

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Apply the Mute and Trace Edits 1. Edit your previous flow by inserting Trace Muting and a Trace Kill/ Reverse. Editing Flow: 01: Display Shots Add

Delete

Execute

View

Exit

Disk Data Input ----Use same parameters as before----

Trace Muting Re-apply previous mutes: -------------------------------------------No Mute time reference: --------------------------------------------Time 0 Type of Mute: --------------------------------------------------------Top Starting ramp: ---------------------------------------------------------30 EXTRAPOLATE mute times?: -------------------------------------Yes Get mute file from the DATABASE?: ------------------------------Yes Select Mute Parameter File: ---------------------------------FB Mute

Trace Kill/Reverse Trace editing MODE ------------------------------------------------Kill Get edits from the DATABASE? ----------------------------------- Yes SELECT trace Kill parameter file --------------- Traces to be killed


Trace Display Number of ENSEMBLES (line segments) / screen -----------------3 ----Default all remaining parameters for this process----2. In the Trace Muting menu click on Invalid to choose the mute parameter file (FB Mute). In ProMAX, each type of parameter table has its own separate menu, such as mute tables, kill trace tables, velocity tables. When selecting the mute parameter file, you are taken to a menu of parameter files for Mutes. 3. In the Trace Kill/Reverse menu select the list of traces to be killed. 4. Execute the flow.

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Notice the effect Trace Muting has on your data. Also, be aware that this effect is only applied to the display. It is not permanent since you have not created a new disk data file.

Example Display with Mute and Edits Applied

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Exit/Stop vs. Exit Continue Flow There are two Exit options in Trace Display. One will terminate the Trace Display and the entire flow, the other will Terminate the Trace Display and allow the remaining processes in the flow to continue running. In this exercise we will look at the difference. 1. Using the same flow, change the input to read the first 20 shots and add a Disk Data Output at the end of the flow. Editing Flow: 01: Display Shots Add

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys?-------------------------------Yes Select dataset---------------------------------------Shots- w/ geometry Trace Read Option--------------------------------------------------Sort Select primary trace header entry--------------------------SOURCE Select secondary trace header entry ------------------------ NONE Sort order for dataset ---------------------------------------------1-20/ ----Default the remaining parameters----

Trace Muting ----Use same parameters as before----

Trace Kill/Reverse ----Use same parameters as before----


Trace Display Number of ENSEMBLES (line segments) / screen -----------------3 ----Default all remaining parameters for this process----

Disk Data Output Output dataset Filename: -----------------------------------------temp New or Existing File? ----------------------------------------------New Record length to output: ----------------------------------------------0. Trace sample format: ---------------------------------------------16 bit Skip primary disk storage?: -----------------------------------------No

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The "0." setting for the Record length to output parameter means output the entire trace, however long it may be. 2. Execute the flow. 3. The first display will have the first three shots. 4. Use the File

Exit/Stop Flow pull down menu to stop the flow.

5. Exit from the flow and go the DATASETS list. 6. Click MB2 on the dataset named “temp” to get the expanded dataset information.

MB2

Notice that this file contains only the first three shots that were displayed. Since the Flow was halted, no additional shots were processed. 7. Execute the flow again. 8. Use the File Exit/Continue Flow pull down menu to stop the Trace Display but allow the flow to continue.

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9. Notice that the flow continues to run. 10. Exit from the flow and go the DATASETS list. 11. With MB2 get the expanded dataset information of the file named “temp.”

MB2

Notice that the file now contains all 20 shots. 12. Delete the file named temp from disk.

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Chapter 3

Database From Full Extraction In many instances you may receive data from contractors or other sources where the basic geometry is already installed in the trace headers. You may elect to build the database from this existing information. In the case where you receive the data in pieces (not all at one time) you may be required to append information to an existing database as more data becomes available.


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o

Overview of Full Extraction

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Extract Information from the SEGY file

o

Complete the Database

o

Load the Geometry to the Trace Headers


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Chapter 3: Database From Full Extraction

Overview of Full Extraction For reprocessing, extraction can read information for building the database from the input trace headers. The database completion is performed subsequently within the spreadsheets.

Full Extraction Path O.B. Notes

UKOOA

Field Data

ASCII

SEG-? Input

UKOOA Import Spreadsheet Import Database Import

Geometry Spreadsheet Ordered Parameter Files Marine Data SSD correction Seismic Data (ProMAX)

Inline Geom Header Load

Extract Database Files

Seismic Data (ProMAX)

Disk Data Output

Valid Trace Numbers Overwrite Trace Headers

Seismic Data (ProMAX)

The full extraction process makes one very critical assumption in that there must be some unique trace header value for all traces of the same shot and receiver. That is, there must be unique source and receiver position numbers, FFIDs, coordinates, or date/time stamps in addition to the recording channel numbers.

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Extract Information from the SEGY File In this exercise, you will read a SEGY file and extract the geometry from the headers to build a database. Project Specifications: •

This project has a rolling multiple cable swath shooting geometry.

•

Shot spacing is variable, with a total of 2094 shots.

•

Group interval is 165 ft, with a total of 13199 receiver locations.

•

Cable spacing is 330 ft, with a total of 78 receiver lines.

•

The source and receiver spacing yields a natural CDP binning of 82.5 ft parallel to the cables and 82.5 ft perpendicular to the cables.

•

This project was collected with surface sources.

•

The number of traces/shot varies, with a maximum of 844 traces/ shot.

Create a New Line and Run Extraction 1. Since you are going to create a new database, the first thing you need to do is to create a new line in your area. This line will be the first

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copy of the Salt3d Project. Select a line name similar to “Salt3d extraction”. 2. Build the following flow in your new line: Editing Flow: 01 - extract database files Add

Delete

Execute

View

Exit

SEGY Input Type of storage to use: ------------------------------------ Disk Image Enter DISK file path name: ----------/misc_files/3d/Salt3D.segy MAX traces per ensemble: -----------------------------------------844 Remap SEGY header values ----------------------------------------Yes Input/override trace header entries ---------------------------------------------------------sou_sloc,,4I,,181/srf_sloc,,4I,,185/

Extract Database Files Is this a 3D survey----------------------------------------------------Yes Data Type----------------------------------------------------------LAND Source index method---------------------------------------------FFID Receiver index method----------------------------COORDINATES Mode of operation -------------------------------------OVERWRITE Pre-geometry extraction?------------------------------------------No Extract CDP binning?----------------------------------------------No Calculate trace midpoint coordinates?------------------------No Extract OFB binning?----------------------------------------------No

Disk Data Output Output Dataset File Name-----------------Shots - With Geometry 3. In the SEGY input step, read the file as described by your instructor There are a varying number of traces per ensemble, with a maximum of 844, and you must remember to remap the SOU_SLOC and SRF_SLOC values from the extended SEGY headers to the ProMAX trace headers (but don’t include the CDP info as shown in the default setting). In this menu the default values for remapping SOU_SLOC and SRF_SLOC will work fine. 4. Remove the specification for the CDP_SLOC but make sure you leave the last “/”. There is no need to extract the CDP information, and in fact, it can cause problems in later exercises.

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5. Select the Extract Database Files parameters. This is a Land 3D project where you will identify all traces coming from a common source by their FFID number and all traces recorded at the same receiver using the receiver coordinates. You will overwrite any previous database information, if any, and do full extraction instead of pre-geometry extraction. Note: Do not extract the CDP or OFB binning, these will be calculated and applied later. Extracting them now can cause problems in later exercises.

6. In Disk Data Output, enter “Shots - With Geometry” for a new output file name. Note: It is not necessary to save this intermediary dataset if disk space is limited. Once the database is completed, the final trace headers can be loaded by reading the SEGY file again, and saving the the finalized dataset at that time. 7. Execute the flow. Extract Database Files does all of the work. The program reads the trace header information and establishes all of the necessary OPF domains and their attributes. The dataset is then stamped with “valid trace numbers,” permitting further processing with a consistent pairing between the OPFs and the dataset. The concept of "valid trace numbers" is an important option for the Inline Geom Header Load process which will be run once the geometry is completed.

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Complete the Database Land 3D Geometry Spreadsheet The following steps complete the CDP binning and database finalization. In this case we will look at the automatic CDP bin grid generation procedures and also adjust the automatically generated grid to fit the survey. 1. Build and execute the following flow: Editing Flow: 02 - spreadsheet Add

Delete

Execute

View

Exit

3D Land Geometry Spreadsheet 2. Review the different menus on the Spreadsheet.

3. Click Help to review additional detail about the use of this dialog.

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4. Open the Receivers Spreadsheet and generate a Basemap using the View View All Basemap pull down menu.

5. Use the Cross domain (double fold)icon to see which receivers are defined as live for each shot. After selecting the icon, hold down MB1 to see the receivers for the shot closest to your cursor. 6. Use MB3 to measure the azimuth of the top row of receivers. Make note of this azimuth for later use. 7. Measure the receiver spacing and cross line spacing and make note for later use. 8. Overlay a color contour graph of the source and receiver elevation on the top of the Basemap. To create this plot, click on Display Recs&Sources Color Contour Elevation. This overlays a colored elevation contour on top of the basemap. Landmark


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9. Select the Views Remove Shot and Receiver based Field of Elevation option at the top of the color contour display to remove the shot and receiver elevation display. You can remove attributes or place different attributes to the top, using options under the Views menu. 10. Open the Sources spreadsheet 11. Click on the Report icon on the XYGraph Display. Click MB1 on any shot location on the basemap. This takes you to that shot location in the source spreadsheet. Since you generated the basemap from the Receivers spreadsheet, the shots are overlaid and “dominant”. Therefore, the Sources spreadsheet must be open.

Note:

If you generate the basemap from the sources spreadsheet, then the receivers are overlaid and “dominant” and the map is expecting to talk to the Receiver spreadsheet. This spreadsheet must be open for the report to respond to the spreadsheet. You can control which map is overlaid using the Views Transparent pulldown menus. Select the map that you want to be overlaid on top of the others by clicking MB1 on the map name. 12. Close the Basemap and both spreadsheet windows. Enter Information in the Setup menu 13. Select Setup from the main pull down menu options.

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Setup Window After Extraction

The setup menu allows you to define global information applying to the configuration and operation of the Geometry Spreadsheet. 14. Select the option of assigning geometry via “Existing index number mappings in the TRC” (this is the default). In the extract process, a shot and receiver location value and x,y coordinate were extracted from each trace header. Every trace knows which shot and receiver it belongs to so the binning can be done by using existing values in the TRC ordered database file. 15. Select 165’ for the nominal receiver station interval, 330’ for the crossline separation and do not fill out the source station interval.

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These numbers were measured from the basemap in the previous steps of this exercise. These numbers are only used for QC purposes. 16. Set the nominal survey azimuth to 87.5 degrees, as measured from the basemap in the previous steps. 17. Answer No to Base Source station coordinates upon a match between source and receiver station numbers. In our case, we have already extracted the correct source coordinates from the trace headers. 18. Enter Surface seismic source for source type. 19. Set units to Feet 20. Do not specify reference coordinates. 21. Specify the font assignment of your choice. 22. Click the OK button. Trace Assignment This exercise illustrates CDP binning procedures. For this example we will automatically compute a CDP grid based on some initial known values and then adjust the grid so that it fits the survey.

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1. In the main menu, click Bin. A submenu appears with options for Assigning the traces to midpoints, defining the bin grid, binning the data, quality controlling the binning, and finalizing the database.

2. Select to Assign midpoints by using “Existing index number mappings in the TRC”, and click OK. In this case the Assignment step is performing the following calculations: •

Computes the Shot to Receiver Offset (Distance)

•

Computes the Midpoint coordinate between the shot and receiver.

•

Computes the Shot to Receiver Azimuth.

Note: Because we ran the full extraction, every trace already knows which shot and receiver to which it contributes.

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3. An Assignment Warning window will pop up warning that some or all of the data in the Trace spreadsheet will be overwritten. Click Proceed.

4. A number of progress windows will flash on the screen as this step runs. A final Status window should notify that you Successfully completed geometry assignment. Click Ok. Look in your job.output listing for possible causes of the problem. These problems are usually related to errors somewhere in you spreadsheet. Automatic Bin Calculation and QC 5. From the main 3D Binning and QC window select “Bin Midpoints”.

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You should get the following window:

CDP Bin Origin and Direction Binning parameters allow you to choose any corner of the project as the origin of the Line, Xline and CDP numbering. You have complete flexibility in the inline and xline directions. You must always remember:

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•

The Y axis is parallel to the specified azimuth.

•

The X axis is 90 degrees clockwise from the Y axis.

•

The grid cell X,Y dimensions must be input as positive numbers.


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o 45 Azimuth __________ Y Inline Parallel to ______

o 45

Y X

Inline 1 Xline 1 CDP 1

Example of Bin Parameters 1

o 225 Azimuth __________ X Inline Parallel to ______

o 45


X Y

Example of Bin Parameters 2 3-14


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Azimuth Approximately 87o Y Inline Parallel to ______

87o

87o


Y

X

This Case 6. Set Azimuth=87, Grid Sizes=82.5 in each direction, supply a Bin Space Name, set the Min Offset to bin=82.5, Offset Bin Increment=165 and select to set the Inlines to be parallel to grid Y axis.

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82.5x82.5 with origin in NW Corner

7. Click Calc Dim to compute the origin of the grid and the Maximum X and Y dimensions.

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82.5x82.5 with origin in NW Corner

8. Save the grid definition by clicking on Save. 9. Select Cancel to remove this window. QC, Edit and Save the CDP Binning Grid The binning grid has now been defined, but it’s a good idea to QC the calculations prior to using the grid.

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1. Select Define binning grid from the main binning window and click Ok.

This will bring up a small map window. 2. Select Display Midpoint Control Points (depending on the color of the background).

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Black

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You should get the following plot:

Mid-point Scattergram for CDP Binning 3.

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Select Grid Open and the grid name that you saved from the Calc Dim operation.


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This step overlays the bin grid on your subsurface data. It will be difficult to read the resulting plot until you have zoomed in the display. An example of the zoomed display is shown below.

Scattergram with Grid Overlay Notice that the grid cells seem to be the right size, but the bins are not parallel to the midpoints and the midpoints are not lined up in the center of the bins. It is likely that we input an incorrect azimuth for the grid.

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4. Select Grid Parameterise,adjust the azimuth to 87.5o, and press the green traffic light icon.

5. The grid is now parallel to the midpoints, but it still needs to be shifted so that the center of the midpoints is in the center of the bins. Move the grid using the appropriate tool from the icons on the left of the display. Try Grid Drawing to help center the grid on the midpoints. Note that Grid Drawing does not move the grid, but toggles the display lines from the edges of the bins to the center of the bins and back. Your instructor can provide additional details on this option.

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6. Zoom in on all the edges and add or delete cells as required to cover all midpoint clusters. The following example shows the process for adding 2 rows of cells to the top of the grid.

MB1 adds row of cells

Total Project Basemap 7. Add or delete cells as appropriate on all 4 sides of the grid.

Note: The original grid would have fit perfectly if we had chosen the correct azimuth of 87.5 instead of 87.

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8. When you have finished adjusting the grid, the grid parameters should match the following display. Adjust the parameters by hand if necessary.

Final Grid Parameters 9. Save your edited grid using the Grid

Save to pull down menu.

10. Enter a grid name and click Ok. 11. Exit from the XYgraph using the File down menu.

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Exit

Confirm pull


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Re-load the final CDP Binning info and Complete CDP Binning 1. Return to the 3D Land Midpoint Binning Window and select Load to bring back the edited grid.

Note The Offset Bin increment and the Inlines parallel to X or Y axis have been reset.

2. Set the Min offset to bin=82.5, Offset binning increment to 165 ft and set the inline to be parallel to theY axis (parallel to azimuth). 3. Click Apply to perform the Binning. 4. When complete, click Cancel.

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Generate a Fold QC Plot and Finalize the Database 1. Return to the 3D Binning and QC window and select to QC the Bin data, select the final bin space and click Ok.

2. This will generate a QC fold plot. Look for a relativley uniform distribution of fold on this plot.

Live CDPs

Zero Fold CDPs

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3. Return the 3D Binning and QC window and generate a QC plot of "Line Space Fold".

4. Examine the resulting plot, and ensure that inlines range from 1308 and xlines range from 1-390 as show in the following plot. If your ranges are wrong, then you probably set the inlines to be parallel to the x axis instead of the y axis in a previous step. Go back and correct it now.

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5. Exit from both of the QC plots. 6. Return to the 3D Binning and QC window and select Finalize the database and click Ok.

7. When complete, click Cancel. 8. Select File Exit from the main spreadsheet menu to exit the Geometry Spreadsheet.

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Load Geometry to the Trace Headers 1. If the geometry in the database looks good, build the following flow (note that we are only processing the trace headers this time): Editing Flow: 03 - load geom to headers Add

Delete

Execute

View

Exit

Disk Data Input Read data from other lines/surveys --------------------------------No Select Dataset----------------------------------Shots - With Geometry Trace read option------------------------------------------------Get All Read the data multiple times?---------------------------------------No Process trace headers only?----------------------------------------Yes Override input data’s sample interval -----------------------------No

Inline Geom Header Load Match by valid trace number?--------------------------------------Yes Drop traces with NULL CDP headers?----------------------------No Drop traces with NULL receiver headers?------------------------No Verbose Diagnostics?------------------------------------------------No

Disk Data Output Output Dataset Filename-----------------”Shots - With Geometry” New, or Existing, File?--------------------------------------Overwrite Record length to output------------------------------------------------0. Skip primary disk Storage?------------------------------------------No 2. In Disk Data Input, enter your input dataset that contains the shots after geometry extraction. Choose to process the trace headers only. The headers will be overwritten with data from the finalized database. Note If you extracted CDP information in the initial step, then you will not be able to process the trace headers only. In this case, you will need to create a new dataset to load the finalized geometry information.

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3. In Inline Geom Header Load, match the traces by their “valid trace numbers”. Since the traces were read and counted with Extract Database Files, you have a “valid trace number” to identify a trace. You have binned all traces; therefore, do not drop any traces. Unless you have a problem, there is no need for verbose diagnostics. 4. In Disk Data Output, overwrite the existing dataset named "Shots With Geometry". 5. Execute this flow. 6. After the flow has completed, go to the datasets list and press MB2 on the dataset name. The dataset should now reflect that both the geometry and trace numbers match the database.

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Chapter 4

3D Geometry from SPS Geometry Assignment is designed to create the standard Ordered Parameter File directories, OPFs, and load standard ProMAX geometry information into the trace headers. The sequence of steps depends upon available information. This chapter serves as an introduction to how to build a ProMAX database given SPS survey data.


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o

Import SPS files

o

Trace Assignment

o

Automatic determination of binning grid

o

Batch method for binning and database finalization


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Chapter 4: 3D Geometry from SPS

3D Land Geometry from SPS Data In this exercise you will import three SPS files that normally accompany modern recording systems. The files contain: •

coordinates for each shot

•

coordinates for each receiver

•

relationships between shots and receivers

You will load these files to fill the SIN and SRF and PAT (Patterns) spreadsheets, and continue with interactive binning. Project Specifications:

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•

This project has a rolling multiple cable swath shooting geometry.

•

Shot spacing is variable, with a total of 2094 shots.

•

Group interval is 165 ft, with a total of 13199 receiver locations.

•

Cable spacing is 330 ft, with a total of 76 receiver lines.

•

The source and receiver spacing yields a natural CDP binning of 82.5 ft parallel to the cables and 82.5 ft perpendicular to the cables.

•

This project was collected with surface sources.

•

The number of traces/shot varies, with a majority of shots with 844 traces/shot and one shot with the maximum of 887 traces.


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Land 3D from SPS Description Build Geometry from SPS files for Land 3D 1. Make a new line called “Salt3d SPS example”. 2. Build the following flow: Editing Flow: 01 - spreadsheet Add

Delete

Execute

View

Exit

3D Land Geometry Spreadsheet 3. Execute the flow. 4. From the global File command, select File Landmark

UKOOA import.


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Enter the directory name as described by your instructor and click on OK. 5. Choose the “salt3d_sps.r” file from the list.

6. From the Format pulldown menu, open a list of saved formats and choose STANDARD SHELL SPS Land 3D. Separate the windows.

7. Check the column definitions by clicking on the words in the Parameter column. Notice that there are two column definitions:

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•

One for the “S” and “R” cards

•

One for the” X” cards


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Also note that, if desired, the coordinates can be altered using the Math OP and Op Value columns. 8. Choose to Apply the format and Overwrite all the data.

While the import is running, you will see a variety of Status windows. Eventually you will see a “Successfully Completed” window. There are still two more files to read. We have read the “R” file but still need to read the “S” and “X” files. 9. Use the File Open pull down menu from the UKOOA File Import window to access the “salt3d_sps.s” file. 10. Choose to Apply the format and Overwrite all the data. 11. Use the File Open pull down menu from the UKOOA File Import window to access the “salt3d_sps.x” file. 12. Choose to Apply the format and Overwrite all the data. 13. Quit from each of the column definition windows and select File Exit from the main import window. Setting Project Constants 1. From the main menu click Setup and input the following information: •

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Choose to "assign midpoints by matching line and station numbers in the SIN and PAT spreadsheets". This will match the receivers and and shots together based on the patterns that were imported from the salt3d_sps.x file.


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•

165 ft receiver station interval

•

Leave the source station interval set to zero, as the spacing is variable.

•

330 ft crossline separation

•

Leave the azimuth at the default value for now, you will enter the correct value later.

•

The source station coordinates are NOT based upon a match between source and receiver station numbers. In nearly all 3D projects, source and receiver station numbering systems are independent of each other, and explicit coordinates are provided for every shot and receiver station.

•

This data were recorded using a surface source and the measurement system is English (feet). We will measure the azimuths on a basemap generated from the receivers spread sheet. Note: Note that the Assignment mode is set to the third option of Matching line and station numbers in the SIN and PAT spreadsheet This mode is generally reserved for SPS input where every shot gets a separate pattern defined for it.

2. Leave the Setup window open and generate a basemap of the project by opening the Receivers Spreadsheet and selecting View All Basemap. View

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Determine Primary Azimuth for Binning 3. Activate the “Double Fold” icon. Measure the azimuth of the receiver lines (use the mouse button help for assistance if necessary.

You should measure a value of approximately 87.5 degrees East of North. Note:

The cross domain plots (MB1 and MB2) only work after the first binning step (assign midpoints) is completed. 4. Go back the Setup window and enter 87.5oas the nominal survey azimuth. 5. Exit from the Setup window by clicking OK.

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6. Exit from the Receivers Spreadsheet by selecting File 7. Exit from the XYgraph using File

Exit

Exit.

Confirm.

Trace Assignment This exercise illustrates CDP binning procedures. For this example we will automatically compute a CDP grid based on some initial known values and then apply the grid using the batch CDP Binning* process. 1. In the main menu, click Bin. A submenu appears with options for Assigning the traces to midpoints, defining the bin grid, binning the data, quality controlling the binning, and finalizing the database.

2. Select to Assign midpoints by using “Matching line and station numbers in the SIN and PAT spreadsheets”, and click Ok. In this case the Assignment step is performing the following calculations:

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•

Computes the SIN and SRF for each trace and populates the TRC OPF.

•

Computes the Shot to Receiver Offset (Distance).

•

Computes the Midpoint coordinate between the shot and receiver.

•

Computes the Shot to Receiver Azimuth.


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An Assignment Warning window will pop up warning that some or all of the data in the Trace spreadsheet will be overwritten. Click Proceed.

A number of progress windows will flash on the screen as this step runs. A final Status window should notify you that you Successfully completed geometry assignment. Click Ok. If this step fails, you have an error in your spreadsheets somewhere. Check in the job.output listing for an error message to help diagnose the problem.

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Spread QC after Trace Assignment 1. Open the Receiver Spreadsheet and generate a basemap using the.View View All Basemap pull down menu.

2. Use the Cross Domain Contribution (Double Fold) icon MB1 and MB2 functions to view which receivers have been defined to be live for each shot and also to see which shots contribute to each receiver. You should observe a split spread of eight cables that rolls on and off the spread at the ends of the survey. 3. Exit from the XYgraph and the Spreadsheet using the File Exit Confirm and File Abort pull down menus respectively.

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Automatic Bin Calculation and QC 1. Select to “Bin midpoints” and click OK. You should get the following window:

2. Set the Azimuth=87.5, Grid Size in X = 82.5, Grid size in Y=82.5, Bin Space Name, Min offset bin center = 82.5,Offset Bin Increment=165 and select to set the Inlines to be parallel to grid Y

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axis, which is parallel to the defined azimuth. In our case, this is parallel to the cable.

3. Click Calc Dim, which computes the origin of the grid and the Maximum X and Y dimensions.

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4. Save the grid definition by clicking Save. 5. Click Cancel to Exit this window. QC the Calculated Grid 1. Select “Define binning grid” from the main binning window and click on Ok.

This will bring up a small map window. 2. Select Display Midpoint Control Points (depending on the color of the background).

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You should get the following plot:

Mid-point Scattergram for CDP Binning 3.

Click on Grid Open and select the grid name that you saved from the Calc Dim operation. This step overlays the bin grid on your subsurface data. Because of the density of the display a zoom will help show and QC the results.

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You may elect to alter the grid by using any of the interactive grid editing icons if desired. (There should be no need to alter the grid). 4. Exit from the XYGraph using File

Exit

Confirm

5. Close the 3D Binning and QC window by clicking Cancel. 6.Select File Exit from the main spreadsheet menu to exit the Geometry Spreadsheet. Complete CDP Binning using the Batch CDP Binning Tool This exercise completes the CDP binning and database finalization steps. 1. Build and execute the following flow: Editing Flow: 02 - CDP Binning Add

Delete

Execute

View

Exit

CDP Binning* Binned Space Name ------- “your grid” This process will perform the CDP binning and Finalization steps in a batch job instead of interactively using the spreadsheet. 2. Once the Binning is complete you can generate the QC plots using the Database. Some example plots are listed below:

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•

View Predefined CDP fold map Check for even distribution of fold

•

View 2D Matrix SIN:X_COORD:Y_COORD:NCHANS:NCHANS Check for shots with an unusually high or low number or receivers (channels)

•

View 3D Crossplot SRF:X_COORD:Y_COORD:ELEV:ELEV:ELEV QC elevations assigned to receivers. You can generate a similar display for shots.


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Chapter 5

Preprocessing and Elevation Statics Both 2D and 3D land data need prestack processing and datum statics. This chapter presents a brief review of typical prestack processing, including top mute, true amplitude recovery, trace editing, deconvolution filter and elevation statics.


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o

Top Mute and Decon Design Gate Picking

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Decon Test and Interactive Spectral Analysis

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Elevation (Datum) Statics

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Trace Statistics and Editing

o

Preprocessing Flows


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Chapter 5: Preprocessing and Elevation Statics

Top Mute and Decon Design Gate Picking The preprocessing flow that you will build uses processes requiring parameter tables. For example, you will need to apply a first break suppression mute and deconvolution. Therefore, you must pick a top mute and a miscellaneous time gate (decon design gate) from a few shot records. Since 3D shot records usually span multiple cables, they will typically have some duplicate offsets. Sorting the shot record by offset may help pick the parameter tables, since both tables are usually time values, interpolated as a function of offset. It may help to plot the traces with variable trace spacing as a function of offset. Isolating Analysis Locations One thing that you may need to do is to determine which shots to use for the table picking to check for the need for space variance. You can generate a map of the shot locations and pick a few shots based on their SOURCE numbers. This introduces a major difference between ProMAX 2D and 3D. In ProMAX 3D all parameter tables are interpolated based on their X and Y locations. In ProMAX 2D all interpolation is done linearly by primary sort key. Another issue here is that you may end up having to read many tapes to capture the shots of interest. In this flow we will output a dataset with just the selected shots. This dataset will come in handy several times during the course of the processing exercise. We will use the dataset to pick the parameter tables, train the neural network and as input to the Apply Elevation Statics and Apply Refraction Statics flows. Having a few shot records immediately available on disk may be a valuable resource. 1. Return to the line labeled "Salt3d - From Extraction". 2. Enter the database, and select View

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2D Matrix...

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3. Select the SIN tab and choose X_Coord for the Horizontal axis, Y_Coord the verticle axis, SOURCE for the Color and Histogram and click OK.

216 306

1031

1988 2089

Shots for Parameter Table Picking 4. Select the tracking tool, point to a few shots and note the SOURCE their numbers. 5. Exit from DBTools.

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You may elect to view 5 shots; one from each corner and one from the center of the project. For example you may elect to use SOURCE numbers 216, 306, 1031, 1988 and 2089. Pick a Top Mute and Miscellaneous Time Gate 1. Build the following flow: Editing Flow: 04- Pick parameter tables Add

Delete

Execute

View

Exit

Disk Data Input Select dataset-------------------------------”Shots - With Geometry” Trace Read Option--------------------------------------------------Sort Select primary trace header entry--------------------------SOURCE Select secondary trace header entry ------------------------OFFSET Sort order for dataset-------------------216,306,1031,1988,2089:*/

Disk Data Output Output Dataset ----------------------------------”Shots - 5 test shots”

Disk Data Input Select dataset-----------------------------------”Shots - 5 test shots” Trace Read Option-----------------------------------------------Get all

Automatic Gain Control AGC operator length----------------------------------------------1500

Trace Display Trace Display MODE ---------------------------------------Grayscale Primary trace LABELING header entry -------------------SOURCE Secondary trace LABELING header entry---------------OFFSET 2. Input your shot record datasets. Select to SORT the input based on Source Numbers with a secondary sort of offset. Note: In 3D, offset and Aoffset are equal, there are no negative offsets. Select a few shots around the project to QC the space variance of the picked tables. 3. Output a dataset to disk that contains the 5 shot records. 4. Set the AGC operator length to 1500 msec.

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5. Select to use the Grayscale color scheme in the Trace Display. 6. Execute the flow. 7. Pick a first break suppression mute using the Picking Top Mute... pull down to remove the first arrivals.

Pick

8. Pick a miscellaneous time gate using the Picking Pick Miscellaneous Time Gates... pull down to use as a time window for the deconvolution design gate. Do not include any first break or refraction energy in this design gate. Poor output from deconvolution could be the result.

Example Mute and Design Gate Landmark


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9. View all 5 shots and adjust the top mute and deconvolution design gate as necessary. 10. Exit and stop the flow using File

Exit/Continue Flow.

If you have viewed all 5 shots, then the "Exit/Stop Flow" and the "Exit/Continue Flow" will have same effect. If you have not viewed all 5 shots, then selecting "Exit/Continue Flow" will ensure that all 5 shots are written to disk. 11. A window will pop up asking if you want to save the edits. Click Yes to save the mute and time gate that you just created.

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Decon Test and Interactive Spectral Analysis Deconvolution testing may become very involved in certain situations. One criterion that you may use to help decide on decon parameters is to look at amplitude (or power) spectra of the trace data before and after decon. If the decon has worked properly, you should see some “flattening”, or “whitening” of the spectrum after decon relative to before. In this exercise we will look at such a comparison on a single shot record. Build a Flow to look at a power spectrum before and after decon 1. Build the following flow: (This first version we will run the ISA in its simplest configuration.) Editing Flow: 05- decon test and ISA Add

Delete

Execute

View

Exit

Disk Data Input Select dataset--------------------------------------Shots - 5 test shots Trace Read Option--------------------------------------------------Sort Select primary trace header entry-------------------------------SIN Select secondary trace header entry ------------------------CHAN Sort order for dataset -----------------------------------------------*:*/

Automatic Gain Control Interactive Spectral Analysis Data select method ---------------------------------------------- Simple Display data by traces or ensembles ------------------ Ensembles ----- All remaining parameters may default ----You should see the following display:

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Interactive Spectral Analysis - Simple Mode You can control the contents of the display by using the Visibility pull down menu and selecting the individual View tiles of interest. 2. Exit from the display using the File menu.

Exit/Stop Flow pull down

3. Edit the parameters of the Interactive Spectral Analysis to go from Simple to Single Subset mode. 4. Execute the flow again. You should get the following display:

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Interactive Spectral Analysis - Single Subset Mode In this mode you can select a Single Subset of the available data for the purposes of computing the average power and phase spectra. You can choose a different subset as many times as you want.

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5. Click on the Select Rectangular Region Icon and then draw a box around an area of interest. The data window and spectral windows will change configuration to match your data selection.

6. Exit from the display using the File menu.

Exit/Stop Flow pull down

7. Edit the parameters of the Interactive Spectral Analysis to go from Single Subset to Multiple Subset mode. Also select to Freeze the selected subsets. 8. Execute the flow again. You should get the following display:

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Interactive Spectral Analysis - Multiple Subset Mode

9. Select the “Select Rectangular Region” icon and draw a box around an area of interest and then select the Options Spectral Analysis pull down menu.

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10. If you select a new area and repeat the Options Spectral Analysis pull down selection a new window will appear. In this way you can compare the spectral results for different areas. 11. Exit the Spectral Analysis Displays. 12. Edit the Flow to do a comparison before and after decon: Editing Flow: 05- decon test and ISA Add

Delete

Execute

View

Exit

Disk Data Input Select dataset-------------------------------------”shots - 5 test shots” Trace Read Option--------------------------------------------------Sort Select primary trace header entry---------------------------------SIN Select secondary trace header entry -------------------------- CHAN Sort order for dataset -----------------------------------------------*:*/

Automatic Gain Control Reproduce Traces Trace grouping to reproduce ----------------------------- Ensembles Total number of datasets ----------------------------------------------2

IF SELECT Primary trace header word ---------------------- REPEAT SPECIFY trace list -----------------------------------------------------1

ELSEIF SELECT Primary trace header word ---------------------- REPEAT SPECIFY trace list -----------------------------------------------------2

Trace Muting Select mute parameter file ------------------------------------FB Mute

Spiking/Predictive Decon Use all defaults except... Select decon gate parameter file --------------------------decon gate

ENDIF Interactive Spectral Analysis Data select method -----------------------------------Multiple Subsets Freeze the selected subset? -----------------------------------------Yes Display data by traces or ensembles --------------------- Ensembles ----- All remaining parameters may default -----

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13. Execute the flow. 14. After the display comes up you can select the Options Spectral Analysis pull down menu to show the spectral estimate for the data before decon. 15. Click on the forward arrow to display the data after decon. 16. Select the Options Spectral Analysis pull down menu again to show the spectral estimate for the data after decon. You can experiment with selecting subsets of the shot record before and after decon. Notice how it remembers the selection window as you change from one shot the next. 17. Run similar tests, and vary the operator length in the deconvolution. You may find better results using a longer (200 ms) operator length.

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Elevation Statics Datum static corrections are generally required for land data to compensate for adverse travel-time effects of topography and variations in weathering thickness and velocity. The process of calculating and applying datum statics within ProMAX includes the following steps: •

Compute static time shifts to take the seismic data from their original recorded times, to a time reference as if the data were recorded on a final datum (usually flat) using a replacement velocity (usually constant).

•

Compute a floating datum (N_DATUM), a smoothed surface used as the processing datum or NMO datum.

•

Partition the total statics into two parts, the Pre (before) NMO term and Post (after) NMO terms relative to N_DATUM.

•

Apply the Pre (before) -NMO portion of the statics and write the remainder to the trace header.

The first three steps occur in the calculation phase and the last step in the apply phase. The calculation phase uses your input parameters in combination with the information in the database and then results are saved in the database. The apply phase reads the information from the database and transfers it to the trace headers. ProMAX offers several options for both phases; which option you should use depends on how you are processing your data. Apply Elevation Statics The first option is to simply add “Apply Elevation Statics” to your flow. Apply Elevation Statics, despite its name both calculates and applies the elevation statics. Because it both reads from and writes to the database, which is shared amongst all the datasets within the Area/Line, you could have a problem if you attempt to run more than one instance at the same time. Therefore, if you are processing a large project in swaths, you will need to wait for Apply Elevation Statics to complete before you run it again for the other datasets in your project. When you run Apply Elevation Statics again for the additional dataset parts, you will automatically recalculate the datum statics in the database for the entire

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project, even though you are only updating the headers for the input dataset. In a large project, the time spent doing the redundant datum statics calculation can be substantial, especially if combined with having to wait to get access to the database. Datum Statics Calculation and Datum Statics Apply To help alleviate these problems, Apply Elevation Statics was split into two separate modules, Datum Statics Calculation and Datum Statics Apply. In a typical workflow for large volume land processing, you would run Datum Statics Calculation once to update the entire project database and then run Datum Statics Apply for each dataset comprising the project. Since Datum Statics Apply only reads the precalculated and saved information in the database and transfers it to the trace headers, you avoid repeating the calculation phase in Apply Elevation Statics. Processing time is saved and the possibility of having several flows trying to write to the database at the same time is eliminated. In addition, Datum Statics Calculation offers the ability to run multiple times and save the output from each run under a unique Run ID. This feature is handy when you wish to compare the results using different parameters as we will do in the next exercise. Before we begin the exercise, let us look at ProMAX datum statics terminology and the calculation algorithms in more detail. Datum Statics Terminology With ProMAX datum statics, you have the option to shift prestack data to a floating datum or a final datum. You supply a final datum elevation and a replacement velocity. The elev_stat_math file then establishes values in the database for F_DATUM, N_DATUM, S_STATIC, R_STATIC, and C_STATIC. Details of this process can best be understood by examining the contents of the elev_stat_math file. This file typically resides in $PROMAX_HOME/port/misc/elev_stat_math. Elevation statics then creates three new header entries: NMO_STAT, FNL_STAT, and NA_STAT. The integer multiple of a sample period portion of NMO_STAT shifts traces to the floating datum in the apply phase. The fractional sample period portion is written to the NA_STAT header entry and applied later.

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If you select to process to a final datum, C_STATIC is set to zero. Since NMO_STAT = S_STATIC + R_STATIC + C_STATIC and C_STATIC = -1.0*FNL_STAT, NMO_STAT is the static that shifts traces to the final processing datum, and FNL_STAT is zero because your data are at the final datum.

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Datum Statics Terminology

S.P.

CDP Receiver

N_DATUM

NMO_STAT

Surface Elevation NMO_STAT FNL_STAT S_STATIC

C_STATIC

R_STATIC

F_DATUM

Database Attributes: N_DATUM = floating datum F_DATUM = final datum S_STATIC = (F_DATUM - ELEV + DEPTH) / DATUMVEL R_STATIC = [(F_DATUM - ELEV + DEPTH) / DATUMVEL] - UPHOLE C_STATIC = 2 * [(N_DATUM - F_DATUM) / DATUMVEL]

Trace Header Values: N_DATUM = floating datum NMO_STAT = S_STATIC + R_STATIC + C_STATIC FNL_STAT = - C_STATIC TOT_STAT = cumulative applied statics NA_STAT = statics less than one sample period which are not-yet-applied (If TOT_STAT = 21.2 ms, and the sample period is 4 ms, NA_STAT = 1.2 ms)

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Comparison of Smoothed Surfaces based on CDP Smoothing In this exercise we will run the Datum Statics Calculation two times with different smoothing parameters and compare the results using the database display tools. Build and Execute a Flow to Compute the N-Datum 1. Build the following flow: Editing Flow: 06- N_DATUM test Add

Delete

Execute

View

Exit

Datum Statics Calculation Elevation or Refraction--------------------------------------Elevation Final datum elevation-------------------------------------------------50 Replacement velocity ----------------------------------------------5500 Database math method --------------------------------Surface Source NMO static method -----------------------------------------Elevations Length of smoother ---------------------------------------------------51 Processing DATUM -----------------------------------NMO DATUM Run ID------------------------------------------------------------------01 2. In the Datum Statics Calculation module use a final datum elevation of 50 ft. with a replacement velocity of 5500 ft/sec. Choose "Surface Source" for the database math method. We will use the default 51 CDP spatial filter of the ELEVATIONS. We will compute statics to a processing datum of the NMO DATUM.

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3. After this flow completes generate two displays from the CDP database:

3D Crossplot: CDP: X_COORD, Y_COORD, ELEV, ELEV, ELEV

3D Crossplot: CDP: X_COORD, Y_COORD, N_DATUM, N_DATUM, N_DATUM

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4. Rerun the same flow but change the smoothing parameter to 101 and change the run id to 02. Regenerate the plot of the new N_DATUM. Note that you will have to re-open the database to see the new N_DATUM. Generating the plot from the already opened database will plot the old N_DATUM with the 51 point smoother.

101 point smoother

3D Wireframe: CDP: X_COORD, Y_COORD, N_DATUM 5. Compare these displays and decide on a value that does sufficient smoothing without greatly changing the local elevation. One major criterion that you might use to help diagnose a good value is to look at the value of N_DATUM in the area of a proposed SuperGather for velocity analysis. You would prefer that all CDPs in a Super Gather have the same (or very similar) N_DATUM value. It is likely that higher values for smoothing are necessary in areas with rapidly changing elevations. The channel feature on the western edge of this survey requires a smoother that is larger than the default value.

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Trace Statistics Utilizing the time information from previously picked first breaks or time gate, Trace Statistics calculates up to eight different statistics for each input trace. These statistics include: •

TRCAMP: average trace energy

•

FB_AMP: average first break energy

•

PFBAMP: average pre-first break energy

•

PFBFRQ: average pre-first break frequency

•

SPIKES: Spikiness: the ratio of amplitudes between the maximum magnitude sample and the average trace signal amplitude

•

FRQ_PK: dominant frequency of data

•

FRQ_DV: Statistical frequency deviation

•

ADECAY: estimated trace energy decay rate in db

In this exercise you will try to identify bad traces with Trace Statistics. Based on the values computed for each trace, you will edit the data volume to remove abnormal traces. Import First Break Picks For this exercise we will import a set of first break picks that have previously been calculated. See the extra exercises later in the manual for information on picking first breaks.

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1. Enter the XDB database display to begin importing picks. 2. Select ASCII

Get.

3. Select User-defined File and enter the path and filename of the first break picks as specified by your instructor (i.e. /data2/ misc_files/3d/salt3dfb.a_db). 4. Select the FBTEDIT1 attribute from the right hand side of the window.

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5. Select Cancel after the plot is complete. 6. Save the imported picks by using the Database command.

Save

7. Exit from the XDB database display and the DBTools display. 8.

Build the following flow:

Editing Flow: 07- Trace Statistics Add

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Execute

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Exit

Disk Data Input Select dataset --------------------------------- Shots - With Geometry Trace read option ----------------------------------------------- Get All

Database/Header Transfer Direction of transfer------Load TO trace header FROM database Number of parameters--------------------------------------------------1 First database parameter--------------TRC F_B_PICK FBTEDIT1 First header entry--------------------------------------------FB_PICK

Trace Statistics Types of trace statistics to compute ---------- TRCAMP FB_AMP PFBAMP PFBFRQ SPIKES FRQ_PK FRQ_DV ADECAY Use first breaks or time gate-----------------------------First Break Form of statistic output---------------- DATABASE and HEADERS 2-character ID for statistics------------------------------------------01 Additional description of statistics-----all shots with edited fb 9. In Disk Data Input, select your Shots - With Geometry dataset. 10. In Database/Header Transfer, transfer the first break picks from the database to the headers. 11. In Trace Statistics, select all of the available statistics, choose to use first breaks, and add a description of the statistics. 12. Execute the flow.

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Analyze the Results 1. Exit the flow and select Database from the global parameter menu. Select and view the different statistical tests in the TRC OPF. Note ranges of values for each statistic for which you might elect to kill the traces. A few examples are shown below.

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Another useful display is to look at the actual shots with header plots of various trace statistics to pinpoint bad traces and their corresponding statistical values.

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2. Edit the previous flow to display the shot gathers. Editing Flow: 07- Trace Statistics Add

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Disk Data Input Select dataset --------------------------------- Shots - With Geometry Trace read option -------------------------------------------------- Sort Interactive Data Access---------------------------------------------Yes Select primary trace header entry---------------------------------SIN Select secondary trace header entry-----------------------AOFFSET Sort order list for dataset-------------------------------------------*:*/ >Database/Header Transfer< >Trace Statistics<

Database/Header Transfer

Direction of Transfer------Load TO trace header FROM database Number of parameters--------------------------------------------------4 First database parameter-------------TRC TRCSTATS ADECAY01 First Header Entry -----------------------(user defined) ADECAY01 Second database parameter----------TRC TRCSTATS TRCAMP01 Second Header Entry --------------------(user defined) TRCAMP01 Third database parameter------------TRC TRCSTATS PFBAMP01 Third Header Entry ----------------------(user defined) PFBAMP01 Fourth database parameter------------TRC TRCSTATS SPIKES01 Fourth Header Entry ----------------------(user defined) SPIKES01

Trace Display Trace Display MODE---------------------------------------Grayscale Primary trace LABELING header entry-------------------SOURCE Secondary trace LABELING header entry---------------AOFFSET Trace scaling option-------------------------------------Entire Screen 3. Sort the dataset by SIN and AOFFSET, and turn on Interactive Data Access. This will allow you, later in the exercise, to select shots from the database and have them displayed in Trace Display. 4. Use Database/Header Transfer to move the previously recorded statistics from the database to the headers for plotting. All of the statistics can be displayed, but the only statistical values that are 5-26


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necessary are; ADECAY, TRCAMP, PFBAMP, and SPIKES. These are the most useful for this particular dataset, other datasets may require some of the other statistical values. 5. Set Trace Display to use grayscale display and scale all of the screen with one scaler. It may be useful to label the SOURCE and AOFFSET of each shot. You may also find it useful to display wiggle traces and zoom in the display instead of using grayscale. 6. Execute the flow. When the display appears, select View Plot Configure...

Header

7. Select the following headers to plot, and give each one a different color: • • •

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ADECAY01 (black) PFBAMP01 (red) SPIKES01 (green)


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•

TRCAMP01 (blue)

8. Use these displays to confirm appropriate min and max values for each statistic. Some of the values might have different ranges of values for different offsets. It will be useful to zoom in on bad traces and note the statistical values associated with each.

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9. Return to the database displays, and use the rectangle selection tool to select some of outlying points. An example is shown below.

1

2

3

10. After selecting the region, press the Bow and Arrow icon to display the shots containing these traces in Trace Display. 11. Repeat the preceding steps on several of the trace statistic plots. 12. Use the header plots and the database display tools to determine ranges and values of particular statistics that will be useful in perfoming trace kills.

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13. Edit the flow one more time to QC the trace editing process and statistical values that you have chosen. Editing Flow: 07- Trace Statistics Add

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Exit

Disk Data Input Select dataset --------------------------------- Shots - With Geometry Trace read option -------------------------------------------------- Sort Interactive Data Access---------------------------------------------Yes Select primary trace header entry---------------------------------SIN Select secondary trace header entry-----------------------AOFFSET Sort order list for dataset-------------------------------------------*:*/ >Trace Statistics<

Database/Header Transfer Same as previous flow

Trace Kill/Reverse Trace editing MODE------------------------------------------------Kill Trace selection MODE-------------Kill/Reverse traces in select list Get edits from the DATABASE?-------------------------------------No PRIMARY edit list header word-------------------------PFBAMP01 SECONDARY edit list header word-----------------------AOFFSET SPECIFY traces to be edited---------------35-100000:2200-50000

Trace Kill/Reverse Trace editing MODE------------------------------------------------Kill Trace selection MODE------Kill/Reverse traces NOT in select list PRIMARY edit list header word--------------------------TRCAMP01 SECONDARY edit list header word----------------------------NONE SPECIFY traces to be edited---------------------------------1.2-1000

Trace Kill/Reverse Trace Kill/Reverse Trace Display

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Editing Flow: 07- Trace Statistics Add

Delete

Execute

View

Exit

Disk Data Input >Trace Statistics<

Database/Header Transfer Trace Kill/Reverse Trace Kill/Reverse Trace Kill/Reverse Trace editing MODE------------------------------------------------Kill Trace selection MODE-------------Kill/Reverse traces in select list PRIMARY edit list header word--------------------------TRCAMP01 SECONDARY edit list header word-----------------------AOFFSET SPECIFY traces to be edited---------------200-50000:2500-50000

Trace Kill/Reverse Trace editing MODE------------------------------------------------Kill Trace selection MODE-------------Kill/Reverse traces in select list PRIMARY edit list header word----------------------------SPIKES01 SECONDARY edit list header word-----------------------AOFFSET SPECIFY traces to be edited---------------100-50000:2200-50000

Trace Display Trace Display MODE---------------------------------------Grayscale Primary trace LABELING header entry-------------------SOURCE Secondary trace LABELING header entry---------------AOFFSET Trace scaling option-------------------------------------Entire Screen 14. Add enough Trace Kill/Reverse processes to accomodate the parameters that you have chosen. Use either the numbers that you have determined in the preceding steps, or the ones that are suggested above.

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15. Execute the flow.

16. Use header plots of the statistics and TRC_TYPE to see which traces have been killed. Adjust parameters as required to edit the appropriate traces. 17. Select File

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Preprocessing Flows The following exercise produces pre-processed, pre-stack data with elevation statics applied. These data can then be input to other 3D specific processes. Build a Flow to Perform the Pre-processing 1. Copy the previous Flow, and add processes as shown in the following page: 2. In Disk Data Input, input the "Shots - With Geometry" file. 3. Use the same Database/Header Transfer and Trace Kill/Reverse parameters as the previous flow. Note that killed traces can be brought back with the Revive Dead Traces process. 4. Add a Trace/Kill Reverse process to remove SIN 580, 662, 731, 920, 995, 1091, 1131, 1700, 1708. These shots are known to be bad. This is the type of information that you might get from Observer Notes. 5. Select the mute you picked in Trace Mute. 6. Select True Amplitude Recovery parameters. Use a 9db/sec gain correction. 7. Select Spiking/Predictive Decon parameters. You can use all of the default parameters except that you need to input a previously picked miscellaneous time gate for the decon design gate. 8. Optional Bandpass Filter. You can apply a bandpass filter in the decon process if desired. 9. Apply the datum statics with the 101 point smoother that were previously calculated in the N_DATUM test exercise.

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10. Add Trace Display Label . 11. Select Disk Data Output, give the new dataset a name, and execute the flow. Editing Flow: 08 - Pre-processing Add

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Disk Data Input Database/Header Transfer Trace Kill/Reverse Trace Kill/Reverse Trace Kill/Reverse Trace Kill/Reverse Trace Kill/Reverse Trace editing MODE------------------------------------------------Kill PRIMARY edit list header word-----------------------------------SIN SPECIFY traces to be edited------------580,662,731,920,995,1091,1131,1700,1708

Trace Muting Select mute parameter file --------------------------------”FB mute”

True Amplitude Recovery Apply spherical divergence corrections ---------------------------No Apply inelastic attenuation corrections ---------------------------No Apply dB/sec corrections?------------------------------------------Yes dB/sec correction constant --------------------------------------------9

Spiking/Predictive Decon Select decon gate parameter file -----------------------”decon gate”

Datum Statics Apply Source datum statics database parameter------------------------------------------------------------SIN GEOMETRY S_STAT02 Receiver datum statics database parameter--------------------------------------------------------SRF GEOMETRY R_STAT02 CDP datum statics database parameter------------------------------------------------------------CDP GEOMETRY C_STAT02

Trace Display Label Trace label --------------------------------------decon and elev statics

Disk Data Output Output Dataset -------------------------------”Shots- pre processed”

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Chapter 6

3D Stack and Volume Comparison In this chapter you will build a flow for importing a 3D velocity field, stack the data, view the stack in the ProMAX 3D Viewer, and use Trace Display to compare two stacks. These display flows are used for the rest of the class to compare different stack volumes.


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o

3D RMS Velocity Field ASCII Import

o

3D Parameter Table Interpolation

o

Picking a Post-NMO Mute

o

Stack 3D

o

CDP/Ensemble Stack

o

3D Stack Volume Displays

o

ProMAX 3D Viewer

o

F-XY Decon

o

3D Volume Comparisons


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Chapter 6: 3D Stack and Volume Comparison

3D RMS Velocity Field ASCII Import One critical part of the initial stack sequence is to apply normal moveout. You may want to build a stacking (RMS) velocity parameter table from a pre-existing field. The following exercise allows you to import an ASCII RMS velocity field for making a parameter table. 1. Build the following flow: Editing Flow: 09-import ascii velocities Add

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Exit

Access Parameter Tables 2. Parameter selection using MB2 produces the following list:.

3. Click on Invalid for the RMS Velocity parameter tables.

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4. Click on Create. Do not click Add.

5. Enter the description name for your imported velocity. Use a name similar to “imported from ascii file”. This opens a parameter table editing window in the form of a spreadsheet. 6. Click on the File

Import pull down menu.

This opens two more windows, an empty viewing window and a File selection window.

7. Input the absolute path name to the directory where the velocity file is stored and append a /* to the end of the path as directed by your instructor. Click Filter. This lists the files and directories stored in this directory. 8. Select the file as indicated by your instructor and click OK.

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This opens the file and shows the contents in the Import viewing window.

9. Click Format. This will open another window.

10. Enter a new format definition name or select a previously defined format (you probably do not have any yet). 11. Click OK.

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Another window will open listing CDP, X Coor, Y Coor, Inline, Xline, TIME and VEL_RMS.

12. Click on CDP and then drag the mouse over the appropriate columns on the import file window to define the correct columns for the CDP value 13. Continue to define column numbers for Time and Vel_rms.

14. Click Apply.

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This will open another window.

15. Select “Overwrite ALL existing values with new import values” and click OK. This will load the values into the table.

NOTE: The input file contains velocity functions using the 3D CDP number as reference. For ProMAX 3D all parameter tables must be referenced to true X and Y coordinates. Be very careful to "resolve" information based on what you know to be valid information for your project. XY coordinates are the prefered reference because they are the most common for anyone who might use the data.

16. Use the Edit Resolve pull down menu to compute the X and Y coordinates for each 3D CDP number. 17. Select to resolve the Coordinates from the CDP ensemble numbers. 6-6


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18. Use the Edit Resolve pull down menu to compute the Inline and Crossline values from coordinates.

All columns should now be complete. 19. Click on File editor.

Exit to save the parameter table and exit from the

20. Check the table for correctness by going back to the list of tables from the User Interface and select to Edit the table. 21. Click on Edit and then select the table name.

Notice that the table does not contain the Inline and Cross line values that we resolved for it. This is NORMAL behavior. The Inline and Crossline numbers are not stored with the table. 22. Click on File

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Abort to exit from the editor.


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3D Parameter Table Interpolation For ProMAX 3D all parameter table interpolation is performed in 3D using the X and Y coordinates of the input information. This applies to Velocities, Mutes, Horizons and any other type of parameter table.

2D Velocity Parameter Table CDP

Time

Vel

1001

0

5000

1000

7000

2000

10000

3D Velocity Parameter Table CDP

Time

Vel

1001

0

5000

1000

7000

2000

10000

X 10000

Y 10000

Iline

Xline

1

1

ProMAX 2D vs. 3D Parameter Tables Velocity Table interpolation is a two step operation. A value at each of three velocity nodes is found at the desired time and then the velocity is interpolated using the Delauney Triangle approach. 6-8


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x

y t

b p

a

c

Known x,y, v, t point Interpolated x,y, v, t point

3D Parameter Table Interpolation Velocity Functions in 3D

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Picking a Post NMO Mute The following exercise demonstrates a method to combine multiple CDP gathers into a single ensemble in order to increase fold and offset distribution. The resulting ensemble can then be used to pick a post normal moveout mute. 1. Build the following flow: Editing Flow: 10 - Pick post-NMO mute Add

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Disk Data Input Select dataset ------------------------------------shots - pre-processed Trace read option ---------------------------------------------------Sort Interactive Data Access----------------------------------------------No Primary trace header entry ---------------------------------------CDP Secondary trace header entry --------------------------------- NONE Sort order for dataset ----------------------------------- 36200[9]/

Ensemble Stack/Combine Normal Moveout Correction Bandpass Filter Automatic Gain Control Trace Display Continued on next page

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Editing Flow: 10 - Pick post-NMO mute (cont) Add

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Disk Data Input Disk Data Insert Ensemble Stack/Combine Type of operation -------------------------------------- Combine Only Input ensembles per output ensemble --------------------------------9 Maximum traces per output ensemble ----------------------------250 Primary Trace Order Header Word -----------------------------CDP Average the primary key values?----------------------------------- Yes Average the X and Y coord. of the primary key-------------------Yes SECONDARY Trace Order Header Word------------------OFFSET Output trace secondary key order ------------------------ Ascending

Normal Moveout Correction Stretch mute percentage ---------------------------------------------0.0 Get velocities from the database?----------------------------------Yes SELECT Velocity parameter file --------------- imported from ascii

Bandpass Filter All default values are acceptable

Automatic Gain Control All default values are acceptable

Trace Display Primary trace LABELING ------------------------------------ CDP Secondary trace LABELING --------------------------- OFFSET 1. In the Disk Data Input, input the Pre-Processed shot file. Select to only read 9 CDPs starting at CDP number 36200. You can make a display from the Database and use the tracking icon to help select the CDP to view. Select View Predefined Trace Midpoint map. 2. Use Ensemble Stack/Combine to build one ensemble of all the input traces.

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Select to join the 9 CDP ensembles into one ensemble and order the traces by OFFSET. Specify a high number of traces per output ensemble (250). Remember to average the CDP numbers and X, Y coordinates. 3. Apply NMO using your best velocities available. Remember to set the stretch mute to 0.0, disabling it. 4. Apply a Bandpass Filter and AGC for data enhancement. The default parameters will be adequate. 5. Display the single ensemble. 6. Pick a top mute to remove any unwanted data.

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7. Using the Picking Pick Top Mute... pull down menu input a new mute table name such as Post-NMO mute (brute) and click OK.

8. Select to interpolate the time picks as a function of AOFFSET. 9. Pick the mute.

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Be careful not to get to close to zero offset at time zero. Normally, you will need to keep the near traces intact for the stack of the shallow section.

10. Select File flow.

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Exit/Stop Flow to save the table, exit, and stop the


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Stack 3D Sorting data for a large 3D volume can be time consuming and expensive. If you are processing seperate swaths of data, ProMAX 3D offers the capability to generate “partial CDP stacks” from input files of any sort order and merge these partial stacks together into one final CDP stack data volume. Of course, if all traces are input to a single Stack 3D execution, no merging is necessary. In the following exercises we will create one complete stack.

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Run Stack3D 1. Build the following flow: Editing Flow: 11- stack - initial Add

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Disk Data Input Select dataset -----------------------------------shots - pre- processed Trace read option ----------------------------------------------- Get All

Normal Moveout Correction Direction for NMO application -------------------------- FORWARD Stretch mute percentage ---------------------------------------------- 0. SELECT Velocity parameter file --------------- Imported from ascii

Trace Muting SELECT mute parameter file -------------- Post-NMO mute (brute)

Disk Data Output Output Dataset Filename-----------------Shot - input to autostatics

Stack 3D Enter name of host ------------------------------------------------------Number of worker threads---------------------------------------------1 Restart with an existing stack? -------------------------------------No Minimum inline number -----------------------------------------------1 Maximum inline number --------------------------------------------308 Minimum crossline number--------------------------------------------1 Maximum crossline number ----------------------------------------390 Exponent of normalization factor --------------------------------- 0.5 Number of normalization scalars per trace --------------------- 100 Apply final datum statics after stack? -----------------------------yes Size of input trace memory buffer (MB)---------------------------- 16 Size of stack trace memory buffer (MB) ----------------------------16

Trace Display Label Trace label---------------------------------------------------------Initial

Disk Data Output Output dataset filename-----------------------------------stack-initial 2. In Disk Data Input, input the pre-processed shots.

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3. In Normal Moveout select the velocity table that we built previously and set the stretch mute to 0.0 percent to disable it. 4. Apply the post-NMO mute picked previously in the Trace Muting flow. 5. Save the processed shots to disk for use in the autostatics chapter later in class. 6. In Stack 3D, enter the minimum and maximum lines contributing from the input dataset.The default values are the project minimum and maximum from the database. 7. In Trace Display Label, label this as the initial stack. 8. Select an output name in Disk Data Output. 9. Execute the flow.

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3D Stack Volume Displays In this exercise we will build flows to display inlines, crosslines, and time slices from the stack volume. Inline Displays The following exercise produces inline displays of the 3D stack volume. 1. Build the following flow: Editing Flow: 12- Display Inlines Add

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Disk Data Input Select dataset --------------------------------------------- stack - initial Trace read option --------------------------------------------------- Sort Interactive Data Access -------------------------------------------- Yes primary trace header --------------( ILINE_NO) 3D inline number secondary trace header ------------------(XLINE_NO) 3D crossline tertiary trace header ---------------------------------------------NONE Sort order for dataset -----------------------------------25-300(25):*/

Bandpass Filter The default parameters will be adequate

Automatic Gain Control The default parameters will be adequate

Trace Display Trace Display MODE----------------------------------------Grayscale Primary trace LABELING --------------(ILINE_NO) 3D inline no. Secondary trace LABELING -----------(XLINE_NO) 3D crossline Trace scaling option-------------------------------------Entire Screen 2. In Disk Data Input, input the initial stack data volume. Sort the input with a primary sort of inline and secondary of crossline. Set the sort order to 25-300(25):*/ 3. Apply a Bandpass Filter and AGC to make the stack look better. 6-18


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4. Set the Trace Display parameters. Set the display mode to grayscale and label XLINE and ILINE. 5. Execute the flow. Use the forward and backward arrows to page through the data. 6. Display the section in color. Choose View 7. From the Color Editor, choose File blue_white_red.rgb file. 8. Close the Color Editor by choosing File

Edit Colormap...

Open... and choose the Close.

9. You can go back to grayscale by Editing the colormap again and choosing grayscale.rgb. 10. Exit the Flow when finished. Crossline Displays The following exercise produces crossline displays of the 3D stack volume.

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1. Build the following flow: (You may want to copy the Display inlines flow to save work.) Editing Flow: 13- Display crosslines Add

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Disk Data Input Select dataset --------------------------------------------- stack - initial Trace read option --------------------------------------------------- Sort Interactive Data Access -------------------------------------------- Yes primary trace header ----------( XLINE_NO) 3D crossline number secondary trace header ----------------------(ILINE_NO) 3D inline tertiary trace header ---------------------------------------------NONE Sort order for dataset -----------------------------------25-375(25):*/



Trace Display Trace Display MODE----------------------------------------Grayscale Primary trace LABELING ----------(XLINE_NO) 3D crossline no. Secondary trace LABELING ----------------(ILINE_NO) 3D inline Trace scaling option-------------------------------------Entire Screen 2. In Disk Data Input, input the initial stack data volume. Sort the input with a primary sort of crossline and secondary of inline. Set the sort order to 25-375(25):*/ 3. Apply a Bandpass Filter and AGC to make the stack look better. 4. Set the Trace Display parameters. Set the display mode to grayscale and label ILINE and XLINE. 5. Execute the flow. Use the forward and backward arrows to page through the data. 6. Exit the Flow when finished.

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Time Slice Displays The following exercise produces time slice displays of the 3D stack volume. 1. Build the following flow: Editing Flow: 14- Display time slices Add

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Time Slice Input Select dataset ---------------------------------------------stack - initial Type of time slice --------------------------------------- Constant time List of times -------------------------------------------- 500-3500(250) Number of samples to stack -------------------------------------------1 Store results in CDP database? ----------------------------------- No Horizontal axis -------------------------------------------- XLINE_NO Horizontal axis increment ---------------------------- INCREASING Vertical axis increment -------------------------------- INCREASING

Trace Display Label Trace label -------------------------------------------------------- initial

Trace Display Trace display MODE---------------------------------------- Grayscale Primary trace LABELING ---------------- slc_time (user defined) Secondary trace LABELING -----------------------------XLINE_NO 2. Set Time Slice Input parameters.

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Select to plot time slices every 250 ms between 500 and 3500 msec. Crossline Number 390

1 1

Inline Number

308

Time Slice Display Orientation To match the display and a map view of this project, set the Horizontal axis to be Crosslines increasing to the right and set the Vertical axis to Decrease, thus plotting Iline 308 on the bottom and crossline 1 on the left. 3. Select the Trace Display parameters. Set the Primary Annotation to slc_time (a user defined header) and the secondary annotation to XLINE_NO. You may also find that using a Grayscale mode makes the display more visually appealing. 4. Execute the flow.

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ProMAX 3D Viewer The ProMAX 3D Viewer is a 3D data volume visualization tool. It will allow you to view a post stack 3D data volume rendered in 3D space where Inlines, Crosslines and time slices can be viewed simultaneously. Box, or cube displays can also be generated. The ProMAX 3D Viewer can display seismic trace data and/or 3D velocity tables. Horizons, faults, and other interpretive entities cannot be displayed using this limited license viewer, but they can be viewed given a full OpenVision license and access to the OpenWorks Oracle database. In this section you will learn how to start the viewer and add different components to the display. Filter and scale the data for display Apply a bandpass filter and agc to the data prior to displaying it in the 3D Viewer. 1. Copy your Display Inlines flow, and edit as follows: Editing Flow: 15a - Filter and Scale Add

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Exit

Disk Data Input Select dataset --------------------------------------------- stack - initial Trace read option ------------------------------------------------Get All



Disk Data Output Output Dataset Filename-----------------Stack - Initial (filterscale) 2. Execute the flow to create a new dataset with filter and agc applied.

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3D Viewer 1. Build and execute the following flow: Editing Flow: 15b - 3D Viewer Add

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ProMAX 3D Viewer* There are no parameters that need to be set for this standalone process. The program may prompt you as to which monitor to display the viewer on and a second prompt will want to know where to display the data selection dialog boxes (These will not appear on computers with one display card). By default the program will start on the higher level graphic screen and you may only get one screen selection opportunity. 2. Select Display Units of feet and click OK.

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3. When the intialization is complete you should get a display similar to the following example:

4. Use the Data ProMAX pulldown menu to access seismic data and/or velocity cube data.

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5. A Dialog box will appear asking you to choose a dataset directory.

6. Select your Salt3d From Extraction line. You may have to first browse for directories. Then select the Seismic Animator tab.

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7. Select your filtered stack, set the inline and crossline increments to 2 and press OK.

8. Use MB1 to rotate the scene. 9. Use MB1 and MB2 to zoom. 10. Use CNTL-MB1 to expand, shrink, move any of the visible planes.

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11. Select Data

Inventory.

12. Select the Box display and then select Modify.

13. Select Line (inline) for the Animator type, slice value of 177, and press Apply. This will display line 177 in the 2D view. 14. Repeat the above step to display a Trace (crossline) and a Timeslice. 15. Use Data Inventory to Hide, Remove, or Modify any of the displayed objects. 6-28


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16. Add a Velocity model to the display by choosing the Data ProMAX pull down option and select the Velocity Animator tab. 17. Select the velocity file that you inported from the ASCII file earlier. Set the line and trace increment to 4, choose the BOX option and use the spectrum color scheme with a 50 % transparency setting and click OK.

18. Both the velocity cube and the seismic cube can be controled with the same tools. 19. Ask your instructor for more information as you experiment with the other options and buttons.

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F-XY Decon The following exercise applies F-XY Decon to the initial stack in order to produce an additional stack volume that looks different from the input. These two stack volumes will then be used to demonstrate the stack volume comparison procedure. Apply F-XY Decon to the Initial Stack 1. Build the following flow: Editing Flow: 16- FXY Decon on initial stack Add

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Disk Data Input Select dataset---------------------------------------------Stack - Initial Trace read option----------------------------------------------------Sort Select primary trace header entry------------------------------ILINE Select secondary trace header entry---------------------------XLINE Sort order list for dataset-------------------------------------------*:*/

F-XY Decon ----The default parameters are adequate---

Trace Display Label Trace label ------------------------------------------ initial (fxy decon)

Disk Data Output Output Dataset Filename---------stack - initial (fxy decon) 2. In Disk Data Input, select the stack with elevation statics applied. Sort by inlines and xlines (*:*/). 3. Use the default parameter for F-XY Decon. Access the help file for more information on this process. 4. In Trace Display Label, label as “initial (fxy decon)”. 5. In Disk Data Output, output a stack with fxy decon file. 6. Execute the flow.

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Display the F-XY Decon Stack You have already built a flow to display some inlines, crosslines and/or time slices from this volume. 1. Reselect your Display Inlines flow. Change the input filename and execute the flow. 2. Display some crosslines and time slices.

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3D Stack Volume Comparison Preparation Eventually we are going to have multiple stack volumes of the same project and we are going to want to compare one volume vs. another. After each processing stage we will be interested in the progress of the stack to make sure that the stack response and lateral continuity are improving. For a 3D volume, you will normally not compare every inline or crossline; instead you will want to select a subset for QC. The problem is that each stack data volume is essentially identical except for the amplitudes and the label header word. Each volume has the same CDP numbers and the same inline and crossline numbers. In order to compare a subset of lines or crosslines efficiently, we will need to sort on a characteristic that varies between the two (or more) stack volumes. The diagram on the next page shows the basic strategy involved in preparing 3D stack data volumes for comparison. When you read multiple datasets within a flow, ProMAX generates a header word for the dataset sequence number called DS_SEQNO. The first dataset read will have DS_SEQNO equal to one and in subsequent datasets DS_SEQNO will increment. Using DS_SEQNO will allow us to read the same inline (or crossline) from multiple stack data volumes and align them in the processing flow so that they are presented to the screen in a specific order. We want the same ILINE_NO from the two volumes to be adjacent in the processing flow so that they can be displayed on the screen simultaneously or can be displayed one after the next for screen swapping comparison.

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DS_SEQNO 1

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3D Stack Comparisons These exercises produce the following three flows: •

One compares inline stacks from different 3D volumes.

•

One compares crossline stacks from different 3D volumes.

•

One compares time slices from different 3d volumes.

Compare Inlines from Two Stack Volumes 1. Build the flow as outlined on the next page. 2. In the Disk Data Input, input the initial stack. Sort using 3D inline as primary and 3D crossline as secondary. Select inlines 25-300(25) and all 3D crosslines (*). 3. In Disk Data Insert, read the initial stack with F-XY Decon and merge it with the original stack observing dataset boundaries but not forcing the datasets to merge. Select Merged for Insert mode. Use the same primary and secondary sort order as Disk Data Input and select the same 3D inlines. 4. Select the Inline Sort parameters. 5. Select 3D inline number (ILINE_NO) for the primary sort key and Input dataset sequence number (DS_SEQNO) from the alternate list for the secondary sort key. Next, select 3D crossline number (XLINE_NO) for the tertiary sort key. Change the maximum number of traces in the ensemble to the maximum number of traces you have per inline (390). This sorts the data so that the same inlines from each volume are adjacent to each other for display. Finally, select Secondary for the Sort key to control end-ofensemble so each inline appears as a separate ensemble.

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6. This flow is an extension of the Display Inlines flow, built earlier. You may want to copy that flow to save yourself some work. Editing Flow: 17- Compare inlines Add

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Disk Data Input Select dataset -------------------------------------------- Stack - initial Trace read option --------------------------------------------------- Sort Interactive Data Access ---------------------------------------------No primary trace header ---------------(ILINE_NO) 3D inline number secondary trace header --------------(XLINE_NO) 3D crossline no tertiary trace header ---------------------------------------------NONE Sort order for dataset -----------------------------------25-300(25):*/

Disk Data Insert Insertion mode --------------------------------------------------Merged Maximum traces per output ensemble -------------------------------0 Select dataset ------------------------------ Stack - initial (fxy decon) Trace read option --------------------------------------------------- Sort primary trace header ---------------(ILINE_NO) 3D inline number secondary trace header --------------(XLINE_NO) 3D crossline no Sort order for dataset -----------------------------------25-300(25):*/ Force datasets to merge ---------------------------------------------No Observe dataset boundaries ----------------------------------------Yes

Inline Sort PRIMARY sort key ----------------- (ILINE_NO) 3D inline number SECONDARY sort-----------------------(DS_SEQNO) Input dataset sequence number TERTIARY sort key-------------(XLINE_NO) 3D crossline number Maximum traces per output ensemble --------------------------- 390 Number of traces in buffer -----------------------------------------800 Buffer type ------------------------------------------------------Memory Sort key which controls End-of-Ensemble----------------Secondary

Bandpass Filter Automatic Gain Control Trace Display

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7. Use the default Filter and AGC parameters. 8. In Trace Display, display one line (2 ensembles) per screen. Select 2 ensembles per screen. Select ILINE and XLINE for the primary and secondary trace labeling header entries. 9. You may elect to display 1 ensemble per screen and the save the screens for comparison. Editing Flow: 17- Compare inlines Add

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Disk Data Input Disk Data Insert Inline Sort Bandpass Filter The default parameters will be adequate


Trace Display Number of ENSEMBLES / screen ------------------------------------2 Primary trace LABELING ---------------(ILINE_NO) 3D inline no Secondary trace LABELING ------------(XLINE_NO) 3D crossline

>Trace Display< Number of ENSEMBLES / screen ------------------------------------1 10. Execute the flow and compare the two datasets. Compare Crosslines from Two Stack Volumes 1. Build the flow as outlined on the next page. 2. In Disk Data Input, input the Stack with elevation statics. Sort using 3D xline as primary and 3D inline as secondary. Select crosslines 25-375(25) and all 3D inlines (*). 3. In Disk Data Insert, read the F-XY Decon Stack.

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Select Merged for Insert mode. Use the same primary and secondary sort order as Disk Data Input and select the same 3D xlines. 4. This flow is an extension of the Compare inlines flow, built earlier. You may want to copy that flow to save yourself some work. Editing Flow: 18- Compare Cross lines Add

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Disk Data Input Select dataset -------------------------------------------- Stack - initial Trace read option --------------------------------------------------- Sort primary trace header -----------------(XLINE_NO) 3D crossline no secondary trace header ------------(ILINE_NO) 3D inline number Sort order for dataset -----------------------------------25-375(25):*/

Disk Data Insert Insertion mode --------------------------------------------------Merged Maximum traces per output ensemble -------------------------------0 Select dataset ------------------------------ Stack - initial (fxy decon) Trace read option --------------------------------------------------- Sort primary trace header ---------------(XLINE_NO) 3D crossline no. secondary trace header-------------(ILINE_NO) 3D inline number Sort order for dataset -----------------------------------25-375(25):*/ Force datasets to merge ---------------------------------------------No Observe dataset boundaries ----------------------------------------Yes

Inline Sort Bandpass Filter Automatic Gain Control Trace Display >Trace Display< 5. Select Inline Sort parameters. Select 3D crossline number (XLINE_NO) for the primary sort key and Input dataset sequence number (DS_SEQNO) from the alternate list for the secondary sort key. Next, select 3D inline number (ILINE_NO) for the tertiary sort key. Change the maximum number of traces in the ensemble to the maximum number of traces you have per crossline (308). This sorts the data so Landmark


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that the same crosslines from each volume are adjacent to each other for display. Finally, select Secondary for the Sort key to control endof-ensemble so each crossline appears as separate ensemble. 6. Use the default Filter and AGC parameters. 7. In Trace Display, display one XLINE (2 ensembles) per screen. Select 2 ensembles per screen. Select XLINE and ILINE for the primary and secondary trace labeling header entries. 8. You may elect to display 1 ensemble per screen and the save the screens for comparison. Editing Flow: 18- Compare Cross lines (cont) Add

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Disk Data Input Disk Data Insert Inline Sort PRIMARY sort key ------------- (XLINE_NO) 3D crossline number SECONDARY sort-----------------------(DS_SEQNO) Input dataset sequence number TERTIARY sort key------------------(ILINE_NO) 3D inline number Maximum traces per output ensemble ----------------------------308 Number of traces in buffer -----------------------------------------650 Buffer type ------------------------------------------------------Memory Sort key which controls End-of-Ensemble----------------Secondary



Trace Display Number of ENSEMBLES / screen ------------------------------------2 Primary trace LABELING -------------- (XLINE_NO) 3D crossline Secondary trace LABELING ----------------(ILINE_NO) 3D inline

>Trace Display< Number of ENSEMBLES / screen ------------------------------------1

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Compare Time Slices from Two Stack Volumes 1. Edit the Display Time Slices flow. It is not as convenient to compare the time slices as with the inlines and crosslines. The most effective way is to execute the same flow twice with two different input files and then size the windows as appropriate to compare the two volumes. Editing Flow: 14- Display Time Slices Add

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Time Slice Input Select dataset ------------------------------------------------- select file Type of time slice --------------------------------------- Constant time List of times -------------------------------------------- 500-3500(250) Number of samples to stack -------------------------------------------1 Store results in CDP database? ----------------------------------- No Horizontal axis ------------------------ CROSS LINE (XLINE_NO) Horizontal axis increment --------------------------- INCREASING Vertical axis increment ------------------------------ DECREASING

Trace Display Label Trace label ----------------------------- volume identifier label text

Trace Display Trace display MODE---------------------------------------- Grayscale Primary trace LABELING ---------------- slc_time (user defined) Secondary trace LABELING ----------(ILINE_NO) 3D inline no

Compare Difference Files from Two Stack Volumes It is sometimes useful to subtrace two trace files and display the difference volume. In our example, viewing the difference between the initial stack and the fxy-decon stack will allow us to see exactly what noise was removed.

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1. Copy the compare inlines flow, and edit as follows: Editing Flow: 17b- Compare difference files Add

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Disk Data Input Select dataset -------------------------------------------- Stack - initial Trace read option --------------------------------------------------- Sort Interactive Data Access ---------------------------------------------No primary trace header ---------------(ILINE_NO) 3D inline number secondary trace header --------------(XLINE_NO) 3D crossline no tertiary trace header ---------------------------------------------NONE Sort order for dataset -----------------------------------------------*:*/

Disk Data Insert Insertion mode --------------------------------------------------Merged Maximum traces per output ensemble -------------------------------0 Select dataset ------------------------------ Stack - initial (fxy decon) Trace read option --------------------------------------------------- Sort primary trace header ---------------(ILINE_NO) 3D inline number secondary trace header --------------(XLINE_NO) 3D crossline no Sort order for dataset -----------------------------------------------*:*/ Force datasets to merge ---------------------------------------------No Observe dataset boundaries ----------------------------------------Yes

Trace Math MODE of operation----------------------------------------Trace/Trace TYPE of trace/trace operation---------------------Subtract Traces Honor ensemble boundaries----------------------------------------Yes How to handle odd ensemble traces-----------------------------PASS

Disk Data Output Output Dataset Filename---------------------------Stack - difference 2. Change the sort order to get all inlines and all crosslines for both datasets. 3. Deactivate the Inline Sort module. In this case we want the datasets to be merged so that we can subract the appropriate traces. 4. Add a Trace Math operation to subtract traces.

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5. Use Disk Data Output to create a new difference volume. 6. Execute the flow. 7. Edit the previous flow to compare the 3 volumes: Editing Flow: 17b- Compare difference files Add

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Disk Data Input Select dataset -------------------------------------------- Stack - initial Trace read option --------------------------------------------------- Sort Interactive Data Access ---------------------------------------------No primary trace header ---------------(ILINE_NO) 3D inline number secondary trace header --------------(XLINE_NO) 3D crossline no tertiary trace header ---------------------------------------------NONE Sort order for dataset -----------------------------------25-300(25):*/

Disk Data Insert Insertion mode --------------------------------------------------Merged Maximum traces per output ensemble -------------------------------0 Select dataset ------------------------------ Stack - initial (fxy decon) Trace read option --------------------------------------------------- Sort primary trace header ---------------(ILINE_NO) 3D inline number secondary trace header --------------(XLINE_NO) 3D crossline no Sort order for dataset -----------------------------------25-300(25):*/ Force datasets to merge ---------------------------------------------No Observe dataset boundaries ----------------------------------------Yes

Disk Data Insert Inline Sort Trace Display

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Editing Flow: 17b- Compare difference files (cont) Add

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Disk Data Input Disk Data Insert Disk Data Insert Insertion mode --------------------------------------------------Merged Maximum traces per output ensemble -------------------------------0 Select dataset ---------------------------------------- Stack -difference Trace read option --------------------------------------------------- Sort primary trace header ---------------(ILINE_NO) 3D inline number secondary trace header --------------(XLINE_NO) 3D crossline no Sort order for dataset -----------------------------------25-300(25):*/ Force datasets to merge ---------------------------------------------No Observe dataset boundaries ----------------------------------------Yes

Inline Sort PRIMARY sort key ----------------- (ILINE_NO) 3D inline number SECONDARY sort-----------------------(DS_SEQNO) Input dataset sequence number TERTIARY sort key-------------(XLINE_NO) 3D crossline number Maximum traces per output ensemble --------------------------- 390 Number of traces in buffer ----------------------------------------1200 Buffer type ------------------------------------------------------Memory Sort key which controls End-of-Ensemble----------------Secondary

Trace Display Number or ENSEMBLES/screen--------------------------------------3 Primary trace LABELING header entry------------------ILINE_NO Secondary trace LABELING header entry--------------XLINE_NO Trace scaling option-------------------------------------Entire Screen 8. Execute the flow.

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Chapter 7

3D Residual Statics ProMAX offers several residual statics routines. In this chapter we will use the Max. Power Autostatics routine. It generally gives good results, even in areas of low signal to noise. Max. Power Autostatics is a stand-alone routine that only requires the input of an autostatics horizon(s) and trace data with NMO applied.


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Chapter 7: 3D Residual Statics

Picking an Autostatics Horizon In this exercise you will pick an autostatics horizon to use in the residual statics calculation. If importing an existing horizon, be certain that the datums match. Typically, an interpreted horizon will be at the final datum while the autostatics horizon will be at N_DATUM. 1. Execute the existing Display Inlines flow. 2. Select Picking Display Menu.

Pick Autostatics Horizons... from the Trace

3. Enter a new name for the horizon, such as Horizon 1, and click OK.

4. Use the default values for Smash and Gate Width.

Pilot traces are built by first flattening all traces along the autostatics horizon over the number of CDPs specified. All of these traces are then summed to form a single pilot trace. It is not critical to determine the smash length at this point, the number can be changed later on in the actual computation step.

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5. Pick a horizon at about 1000 ms. Keep in mind that this is a shallow

gate when considering the post-NMO top mute. Only about half to two-thirds of the offsets will contribute to the statics estimate. Refer to the gather where you picked the top mute in Chapter 6, at about page 13. The correlation window (gate) will be centered on this horizon. 6. Continue picking the horizon on each of the chosen inlines (25300(25)).

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Picking the horizon will be difficult on some lines due to low signal to noise. Use your best judgement to approximate the structure in these areas. Picking exact peaks or troughs is not important, and you may chose to pick slightly different horizons on each inline. Neither the location nor shape of the horizon is used in calculating the actual statics. The horizon simply controls where correlations are calculated and what structure is removed prior to smashing CDPs together for pilot traces. In general you want this horizon to be relatively smooth. 7. Select File Exit/Stop Flow after picking the horizon on all of the displayed lines.

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Calculate Residual Statics 1. Build the following flow: Editing Flow: 19 - Max Power Autostatics Add

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Parallel Max. Power Autostatics* Number of processors to use-------------------------------------------0 Select Trace Data file--------------------Shots - input to autostatics Select Autostatics horizon file-------------------------------Horizon 1 Extend horizon to survey edge--------------------------------------Yes Maximum number o f iterations---------------------------------------4 Maximum static allowed (ms)-----------------10.0, 15.0, 20.0, 30.0 Compute Statics for whole line?------------------------------------Yes Length of smash INLINE-----------------------------------------------3 Length of smash CROSS LINE----------------------------------------3 ------Default all remaining parameters------2. Select as many processors as possible, or use 0 to get the active number of processors on the machine. Runtime for this process can be significantly reduced if more than one processor is available. However, the input dataset should be CDP-sorted in order to utilize the additional CPU capacity. 3. Select the input dataset that was created during the initial stacking process. 4. Select 4 iterations, and set the maximum static for each iteration to 10.0, 15.0, 20.0, 30.0. The first iterations should use a small value for maximum static to help avoid cycle skips. As the static solution begins to stabilize, later iterations can be opened up to allow larger static values. 5. Set the INLINE and CROSS LINE smash values to 3. 6. Default the rest of the parameters.

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7. Execute the flow. On a 1.2 GHz Linux machine, this process runs about 20 minutes for each iteration on this dataset. It should only be executed when there is a sufficient amount of time for the process to complete. Ideally, this exercise would be the last exercise of the day so that the job could run overnight. If timing is an issue, then just run 1 iteration instead of 4 to save time. QC the Picks from the Database 1. Make a plot the from the SIN domain 2d Matrix: X_COORD: Y_COORD: SPWR0000: SPWR0000.

Notice that most of the static values are near 0 ms, but there are a few large outliers. You may want to view these particular shots in trace

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display to determine if they if there is something wrong with these shots, or if the static value appear to be legitimate. Optional exercise Try using Interactive Data Access to send shot locations from the database display to Trace Display. 1. Make a flow (or edit a previous flow) to display the “Shots - PreProcessed” file with Disk Data Input, AGC, and Trace Display. Sort the data by SOURCE and OFFSET with a sort order of *:*. Be sure to turn on Interactive Data Access. 2. Wait until the first shot is displayed. Return to the database display of the source statics. Select a shot with the rectangle selection tool. Click the Bow and Arrow Icon to have the selected shot displayed in Trace Display. You might also find the histogram is useful for isolating particular ranges of static values to examine.

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Display the Receiver Statics 1. Make a similar Database display for the receivers.

Notice the pattern of statics that follows the North-South trending channel on the East side of the display.

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Static Application and Stack Comparison In this exercise, you will apply residual statics, create stacks, and compare them with the brute stack. We will also prepare the necessary pre-stack dataset for future processing. The only required pre-stack output from this flow is a dataset for velocity analysis. 1. Copy the existing stack flow and edit it to create the following flow: Editing Flow: 20 - resid stat stack Add

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Disk Data Input Apply Residual Statics Reproduce Traces SPLIT Normal Moveout Correction Trace Muting Stack 3D Trace Display Label Disk Data Output END_SPLIT 3D Supergather Select Bandpass Filter Automatic Gain Control Disk Data Output This is a complex flow. The basic steps can be divided as follows • • • •

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Apply the residual statics. Apply Normal Moveout and the post NMO mute and produce a stack of the data with the residual statics applied. Select the grid of line/crossline supergather locations for velocity analysis. Apply pre-velocity analysis processing and output a temporary dataset created specifically for velocity analysis.


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Apply the Residual Statics and Reproduce the Traces: Editing Flow: 20- resid stat stack (cont) Add

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Disk Data Input Select dataset -----------------------------------shots - pre-processed Trace read option ----------------------------------------------- Get All

Apply Residual Statics Normal database entry naming mode?--------------------------- Yes Type of residual statics to apply-----------Max. Power Autostatics

Reproduce Traces Trace grouping to reproduce ------------------------------Ensembles Total number of datasets ----------------------------------------------2 1. Input the shot organized dataset with pre-processing. 2. Apply the residual statics that were generated by the Max. Power Autostatics process. 3. Use Reproduce Traces to make two copies of each ensemble. One copy will be stacked. The other copy will be processed in preparation for velocity analysis.

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Stack the Data Editing Flow: 20 - resid stat stack (cont) Add

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SPLIT Trace selection MODE ---------------------------------------- Include Primary trace header ---------------REPEATED data copy number Secondary trace header ---------------------------------------- NONE SPECIFY trace list ----------------------------------------------------1/

Normal Moveout Correction Direction for NMO application ------------------------- FORWARD Stretch mute percentage ---------------------------------------------- 0. Apply any remaining static during NMO?------------------------Yes SELECT Velocity parameter file --------------- imported from ascii

Trace Muting SELECT mute parameter file ----------------- post nmo mute (brute

Stack 3D Keep all parameters the same as the initial stack

Trace Display Label Trace label ---------------------------------------------Residual Statics

Disk Data Output Output Dataset Filename--------------------Stack -Residual Statics

END_SPLIT 4. Split the flow and pass the first REPEATED copy through the stack path. 5. In NMO, Trace Muting, and Stack 3D, keep all parameters the same as the initial stack. 6. In Trace Display Label, identify this as the residual statics stack. 7. In Disk Data Output, output a stack with residual statics. 8. End the SPLIT.

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Split the Flow and Output the Data for Velocity Analysis Our first task here is to decide on the velocity locations. This issue will be discussed more thoroughly in the next chapter. For now, we can keep our options open by generating supergathers that are spatially large. We can always make them smaller in subsequent flows.

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Proposed CDP Center Positions For Analysis We will use 3D Supergather Select to identify velocity locations at the intersection points of every 50th inline with every 100th crossline. That is, inlines 50, 100, 150, 200, 250 at crosslines 50, 150, 250 and 350, which gives us 20 velocity analysis locations. Using a “span” of 5 inlines and 9 crosslines will provide large supergathers and give us plenty of flexibility for this exercise.

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3D Supergather Select evaluates each trace. If it falls within a supergather location, its header is updated to indicate that location in the header attribute SG_CDP. All traces the do NOT belong to a supergather location are dropped from the flow. Because of this behavior, you should only use 3D Supergather Selection near the end of a flow. Editing Flow: 20- resid stat stack (cont) Add

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3D Supergather Select Location selection ----------------------------------------------- Grid Minimum center inline number ---------------------------------- 50 Maximum center inline number -------------------------------- 250 Inline increment ----------------------------------------------------- 50 Inlines to combine ---------------------------------------------------- 5 Minimum center cross line number ----------------------------- 50 Maximum center cross line number --------------------------- 350 Cross line increment ---------------------------------------------- 100 Cross lines to combine ---------------------------------------------- 9



Disk Data Output Output Dataset Filename------------------------Supergathers Trace sample format -----------------------------------------8 bit 1. Identify a grid of velocity locations for 3D Supergather Select. You might choose different values for number of inlines and crosslines to combine, such as 3 by 3 or 1 by 9. Methods for choosing this will be discussed in the next chapter. 2. Apply a bandpass filter and AGC to the data. 3. Output a dataset in 8 bit format to save some disk space. We can use 8-bit samples as long as we understand these traces are only intended for velocity analysis.

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4. Remember that earlier in this flow, we used SPLIT to include all traces with REPEAT=1. Everything else will have to come through 3D Supergather Select. 5. Execute the flow. 6. Use the Compare Inlines and Compare Crosslines flows to compare the results after residual statics with those after the initial stack.

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Chapter 8

Velocity Analysis and the Volume Viewer In this chapter, we will look at two ProMAX velocity tools: Velocity Analysis and the Volume Viewer/Editor. These tools can interact with one another via the Pointing Dispatcher. In the next exercises, we will look at this interaction. Prior to analyzing the velocities, we will precompute data for input into Velocity Analysis. Precomputing improves the interactive performance of Velocity Analysis.


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Chapter 8: Velocity Analysis and the Volume Viewer

Velocity Analysis Introduction Velocity Analysis provides comprehensive interactive velocity analysis, velocity quality control, and velocity field modification capabilities. Velocity Analysis is a “socket tool”; therefore, preprocessing of data can be performed in the same flow before passing the data on to analysis. Velocity Analysis also allows random access to the dataset. With this feature, you can go back to the previously processed ensemble, rewind the data to the first CDP specified in the sort order for dataset, or go to any CDP in the dataset by specifying a new sort order. Velocity Analysis provides a variety of data display options, and allows picking in the semblance panel or the stack data panel. Picks made in either panel are automatically shown in the other panel. The user can choose which components to display via menu options prior to execution, and most settings can be changed interactively in the analysis tool. Analysis locations commonly are chosen on a 1 kilometer grid for initial velocities and on 0.5 km grid for final velocities. The supergathers corresponding to these locations were created in an earlier flow using the 3D Supergather Select module. Optionally, supergathers can be generated using the 2D or 3D Supergather Formation* modules, but these modules use considerable amounts of memory and their performance may be less than desirable. Velocity Analysis tool displays a single analysis location at a time. Each input supergather is processed to create several types of data that can be used in the interactive tool. These include a velocity semblance panel, a CDP gather with regularized offset sampling, and a set of stack panels using a range of velocity functions. This specialized ensemble of data can be generated in the Velocity Analysis module, or they can be generated by the Velocity Analysis Precompute module. Precomputing these data before input to Velocity Analysis has two advantages: 1) it is faster when advancing to the next analysis location because it has little calculation to do, and 2) it allows use of interactive data access (IDA) which allows immediate access to any analysis location when used with the Volume Viewer/Editor tool. Using raw supergathers as input can allows great flexibility, including options to change parameters and recalculate the semblance, gather and 8-2


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stack panels. Additionally, when picking mutes on the gather panel, you can recalculate all panels in order to optimize the velocity function and top mute simultaneously. Interactive data access is not available when using raw supergathers as input, so you can only move forward one location at a time and cannot move backward. However, the velocity field that you are picking can be viewed and updated interactively in the Volume Viewer/Editor tool. In the first exercise we will concentrate on the Offset Distribution analysis to find good supergathers and then proceed with the velocity analysis.

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3D Supergather Generation and QC Supergathers are generated so that the data used for picking velocity functions is well sampled in offset and provides sufficient signal-tonoise ratio. Commonly, we gather traces from a span of adjacent inlines and crosslines into one supergather for each velocity analysis location. The “span” may be a value of 1or larger in either inline or crossline. 3D supergathers are formed by using 3D Supergather Select or 3D Supergather Formation*. The illustration below shows 3-by-3 and 5-by1 supergathers.

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Supergather Generation and Offset Distribution QC In the previous chapter, you created a file called “supergathers” that was produced from the module 3D Supergather Select. This is the preferred module for generating supergathers because it is much more efficient than 3D Supergather Formation and Inline Sort, especially for larger datasets. Many land shooting geometries give irregular offset distributions, especially when shots are moved from their preferred locations. In this exercise, we will build supergathers using the 3D Supergather Formation* process. We will QC the supergathers for trace content and offset distribution prior to running the velocity analysis. We will compare offset distributions for a 3x3 spatial supergather, a 5x5 spatial supergather and a 9x1 inline supergather. This procedure is not particularly valuable for marine data, which almost always has very consistent offset distribution. If you only intend to process marine data, you may choose to skip the next few pages and proceed to the section titled Precomputed Velocity Analysis. 1. At the bottom middle of the user interface, click on “Option” and make sure that “yes” is selected for “Use headers exclusively for sort”. This will improve performance considerably, and cut down on memory use. The input dataset is stamped as having trace numbers that match the database. Because of this, the default behavior is to build to sort table based on the entire database, rather the small

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subset of traces in our input dataset. It will be much more efficient to sort based on the headers of the dataset, rather than the database. 2. Build the following flow: Editing Flow: 21-Velocity analysis Add

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3D Supergather Formation* Select dataset -----------------------------------------supergathers Presort in memory or on disk? ------------------------------- memory Maximum CDP fold --------------------------------------------------39 Location selection--------------------------------------------------Grid Minimum center inline number ------------------------------------- 50 Maximum center inline number ----------------------------------- 250 Inline increment -------------------------------------------------------50 Inlines to combine ------------------------------------------------------3 Minimum center cross line number ---------------------------------50 Maximum center cross line number ------------------------------ 350 Crossline increment -------------------------------------------------100 Crosslines to combine -------------------------------------------------3

Inline Sort PRIMARY sort key -------------------------- SG_CDP (user defined) SECONDARY sort key --------------------------------------- OFFSET Maximum number of traces per output ----------------- 600

Trace Display Number of ENSEMBLES per screen ------------------------ 20 Trace display MODE----------------------------------------Grayscale Header Plot Parameter ---------------------------------- OFFSET Primary trace LABELING ------------- ILINE_NO (3d inline) Secondary trace LABELING ---------- XLINE_NO(3d xline) 3. Select the 3D Supergather Formation* parameters. Although 3D Supergather Formation* is labeled as a stand-alone process (*),the module does not write data to disk. Therefore, an output tool such as Disk Data Output or a display tool such as Trace

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Display or Velocity Analysis should follow the supergather formation in the same flow. The input data is the preprocessed file that we made specifically for the velocity analysis in 8 bit format with a bandpass filter and AGC applied. The maximum CDP fold is 39, which is recognized from the database. Define your supergathers to be centered at inlines 50-250 by 50 and at crosslines 50-350 by 100. Combine 3 CDPs along inlines and crosslines. This will initially define a 3 by 3 “box” around the center CDP. Each spatial supergather generated by 3D Supergather Formation* is assigned a value of the center CDP for the new header word SG_CDP. 4. Sort the input SG_CDP ensembles with a secondary sort of OFFSET. This will allow us to display the supergathers so that we can see the supergather effect in linear offset space. There will be approximately 600 traces per output ensemble after the Supergather Bin sort (when we test 5x5 later in the exercise). 5. Display the supergathers for QC. Display 20 ensembles with ILINE_NO as the primary annotation and XLINE_NO as secondary annotation. This will give a good idea of which inlines and crosslines contribute to each SG_CDP ensemble. Use the Header plot option in the menu to plot the trace offsets above the supergathers. You should look for linearity of the offsets. 6. Experiment with different supergather parameters and see which provides the most consistent offset distributions. Try using 1 inline and 9 consecutive CDP’s at each location. • • • • • Landmark

Minimum Line = 50 Maximum Line = 250 Increment =50 Inlines to combine=1 Minimum Xline =50 ProMAX Seismic Processing and Analysis

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• • •

Maximum Xline = 350 Inc = 100 Crosslines to Combine= 9

Try a 5x5 CDP supergather at the same centers.

Offset Distribution Comparison Plots

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Precomputed Velocity Analysis Preparing supergathers and performing Velocity Analysis interactively on a large 3D survey may require a lot of time. Therefore, you may elect to use Velocity Analysis Precompute to calculate the semblance and stack data at the supergather locations. This can significantly speed up the interactive Velocity Analysis session, especially when a large number of CDPs are used to create the supergathers. Another advantage of using Velocity Analysis Precompute is that precomputed data provides quicker use of the random access capability available in Velocity Analysis. It also allows simultaneous use of the Volume Viewer/Editor and the ProMAX 3D Viewer. The Volume Viewer/Editor provides map (time slice) and vertical cross section views of the velocity volume. The ProMAX 3D Viewer provides a 3D cube rendering of the velocity volume. Through the use of a “pointing dispatcher” or PD, the Volume Viewer/Editor will automatically update the velocity volume display with the picks made in Velocity Analysis. Run the Precompute 1. Expand the Velocity Analysis flow and “comment out” any existing modules (e.g., 3D Supergather Formation) using MB3. 2. Add the modules Disk Data Input, Velocity Analysis Precompute and Disk Data Output. The input needs to be sorted on SG_CDP. 3. If your input dataset was created with larger supergathers than you want to use in this flow, you can add the following modules immediately after Disk Data Input in order to “trim down” the gather to a smaller size: 3D Supergather Select followed by Ensemble Redefine. Choose the same inline and crossline locations, but specify a smaller number of inlines or crosslines for each location. Ensemble Redefine should ask for “change” of SG_CDP, and maximum fold appropriate for the size of the supergathers you want.

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Editing Flow: 21-Velocity analysis Add

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Disk Data Input Trace read option ----------------------------------------------- Sort Select primary trace header entry ----------------------- SG_CDP Sort order list for dataset -----------------------------------------*

Velocity Analysis Precompute Number of CDPs to sum into gather --------------------------------25 Apply partial NMO-to-binning-------------------------------------Yes Apply differential CDP mean statics-------------------------------Yes Absolute offset of first bin center --------------------------------82.5 Bin size for vertically summing offsets ---------------------------165 Maximum offset -------------------------------------------------- 10000 Minimum semblance analysis velocity ------------------------- 4000 Maximum semblance analysis velocity ----------------------- 15000 Number of semblance calculations----------------------------------50 Semblance velocity axis--------------------------------Equal Velocity Semblance sample rate (in ms) ------------------------------------- 20 Semblance calculation window ------------------------------------- 40 Number of stack velocity functions----------------------------------21 Number of CDPs per stack strip-------------------------------------25 Scale stacks by number of live samples summed-----------------Yes Method of computing velocity fctns------------------Top/base range Velocity variation at time 0------------------------------------2000 Velocity variation at maximum time--------------------------5000 Get guide function from existing parameter table?--------------Yes Velocity guide function table name--------Imported from ASCII Maximum stretch percentage for NMO ----------------------------30 Long offset moveout correction---------------------------------NONE Use a picked mute?-----------------------------------------------NONE

Disk Data Output Output Dataset Filename-----------------temp-velanal precompute Trace sample format -----------------------------------------------8 bit

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4. Parameterize the Velocity Analysis Precompute. Your choices for number of CDPs to sum in the gather and number of CDPs in the stack strips will depend on what you used in generating the supergather that is input. If your gathers contain more than 1 inline, you should always choose the number of stack strips to match the total number of CDPs contained in the supergather. For a 5x5 supergather, you should choose 25 CDPs for the stack strip. For the velocity analysis gather, you can choose any number equal to or less than the number of CDPs in the supergather. Note: The stack strip will be composed of “real” CDP stacks, and if the supergathers contains more than one inline, you may see discontinuities in the stack “structure” if there is significant geologic dip in the data. When there is considerable crossline dip, you should consider using only one inline for the supergather. Use 82.5 for the offset of the first bin center and 165 for the offset bin size. This controls the re-binning and sub-stacking of the gather traces that are used for the semblance calculations and the reference gather this is seen in the interactive analysis tool. Choose a velocity range from 4000 to 15000 ft/sec. for the semblance. The number of stack panels to create is typically in the range of 7 to 25. More stack panels may allow sharper discrimination of optimum stack. Use “Top/base range” and 2000 to 5000 to control the reference functions that are used for the stacks. This range is applied to both sides of the guide functions, which gives a span of 4000 fps at 0 time and 10000 fps at the maximum time. 5. Enter a new data set name in Disk Data Output. 6. Execute this flow.

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Velocity Analysis 1. While the job is running, edit the flow to toggle everything off and add Disk Data Input and Velocity Analysis. Editing Flow: 21-Velocity analysis Add

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Disk Data Input Select dataset -------------------------temp- velanal precompute Trace read option ------------------------------------------------Sort Interactive Data Access ---------------------------------------- Yes primary trace header ------------------------------------SG_CDP secondary trace header ------------------------------------NONE Sort order for dataset ---------------------------------------------*/

Velocity Analysis Select display DEVICE: -----------------------------------This Screen Table to store velocity picks: ---------------after resid stat b4 DMO Is the incoming data Precomputed?: ------------------------------Yes Set which items are visible?-----------------------------------------No Set semblance scaling and autosnap parameters?:---------------No Pick/apply a mute?-----------------------------------------------NONE Select/Display horizon(s)?: -------------------------------------NONE Interact with other processes using PD?:-------------------------Yes Get guide function from existing param. table? -----------------Yes Vel. guide function table: --------------------imported from ascii Maximum stretch percentage for NMO: ---------------------------30 Long offset moveout correction?:------------------------------NONE Interval velocity below last knee: ------------------------------------0 Copy picks to next location------------------------------------------No 2. In Disk Data Input, input the dataset from the Velocity Analysis Precompute execution of the flow. Turn IDA on by going to SORT mode. This will allow Velocity Analysis to communicate with the Volume Viewer for Velocity field QC. 3. In Velocity Analysis, choose Yes for “Is the data precomputed?”. 4. Set the Velocity Analysis parameters.

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When you first parameterize the Velocity Analysis process, a subset of the parameters will be visible, so begin by setting the “global parameters” highlighted in the flow. Be sure to create a table to store velocity picks such as “after resid stat b4 DMO”. Next, select Yes for “Set semblance scaling and autosnap parameters” to display the semblance submenu. The default settings will work fine so turn off the semblance submenu by clicking No for Set semblance scaling and autosnap parameters. The submenu parameter settings will be retained and used even though they are not visible. 5. The parameter “Set which items are visible works” the same way. Both the visibility and semblance parameters can also be changed interactively from within the velocity analysis tool. 6. Use the previous velocity field as a guide. 7. After the precompute flow has completed, execute the flow and begin picking velocities in the Velocity Analysis display. The velocity semblance, a corresponding CDP supergather, and the CVS strips are displayed. Another available display is a peak semblance histogram with interval velocities derived from the RMS picks. 8. Begin picking a velocity table by using the Pick icon, and pick a function. As you pick velocities on the semblance plot, the picks are also displayed on the CVS strips and the interval velocity plot is modified. You may also pick velocities on the CVS strips. 9. Select Gather Apply NMO to see the currently picked velocity applied to the gather. Note the CDP, ILN, and XLN values that appear in the upper left hand corner of the display. These provide the center CDP value, the range of inlines and the range of crosslines included in the current velocity analysis supergather. Your first velocity analysis center should have values of CDP 19260, ILN 50, and XLN 150.

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Velocity Analysis Icons •

Next ensemble: Proceed to and process the next ensemble in the dataset. If you are currently processing the last ensemble in the dataset, this button will rewind the data and bring up the first ensemble.

•

Previous ensemble: Step backward one ensemble and process the ensemble before the current ensemble. If you are currently processing the first ensemble of the dataset, this button is “grayed out” and does not do anything.

•

Rewind: Rewind the dataset and go back to the first ensemble as specified in the sort order.

•

Point Dispatcher(PD) save and send the velocity picks in the current ensemble to the Velocity Viewer/Editor.

10. After you pick the first location and move to the second you may want to overlay the function that you just picked as a second guide. You can do this by clicking on View Object Visibility... then toggle on Average of all CDPs (blue). This will display the average of all of the functions that have been picked in the output table to date. Your velocity picks are automatically saved to an RMS velocity ordered parameter file when you move from one location to the next or Exit the program. You also have the option to save picks using the Table/Save Picks option. Using the Volume Viewer As you pick velocities along a line using the Velocity Analysis tool, you may want to QC your new velocity field. This can be accomplished by simultaneously viewing a color isovelocity display of the entire velocity volume. The tool used for this is a standalone process called the Volume Viewer/Editor, and should be executed while you are running Velocity Analysis, as outlined below.

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1. After picking one or two locations, leave the Velocity Analysis Window. 2. Return to the ProMAX User Interface. Build a new flow to run the Volume Viewer/Editor. Editing Flow: 22 - Velocity Field QC Add

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Volume Viewer/Editor Work in Time or Depth-------------------------------------------- Time Unit System ----------------------------------------------------Database Surface Coordinates------------------------------------------ILN/XLN Source of depth coordinate------------------------------------ Volume -----------------------------------------------------------------------------Input Volume Type------------------------- Stacking (RMS) Velocity Select input volume-----------------------after resid stat b4 DMO Velocity volume reference datum----------------------------Floating -----------------------------------------------------------------------------Display poststack seismic data -------------------------------------No -------------------------------------------------------------------------To which datum are the horizons referenced?---------Final Datum Interact with Velocity Analysis------------------------------------- Yes Display gather locations--------------------------------------------Yes 3. Set the parameters for Volume Viewer/Editor. Make sure you input the same velocity volume (table) that you are currently using in Velocity Analysis. Also, make sure you select Yes to “Interact with Velocity Analysis?” This will enable the PD (pointing dispatcher) to communicate with the Velocity Analysis already running. 4. Execute the flow containing the Volume Viewer/Editor, and return to the Velocity Analysis display. Two Volume Viewer/Editor windows will appear: ProMAX/ Volume Viewer: Map and ProMAX/Volume Viewer: Cross Section.

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You will want to try different ways of arranging the windows on the screen until you have made an arrangement that is workable. The following diagram is one possible way to arrange the windows on the screen if you only have one screen to work with:

Possible Window Arrangement If you have not yet picked any velocities in Velocity Analysis, the velocity displays will contain zero values and therefore the screen will be all blue and the velocity and space scales will be very large. If you have picked at least one velocity function, you will only see a vertical color variation in the Cross Section window. The Map window displays a time slice through the current velocity volume at the position of the heavy, gray line that appears in the Cross Section window. You can change the time slice by activating the “Select a horizontal slice” icon in the Cross Section window and clicking MB1 at the appropriate time in the Cross Section window. The Map window also displays an outline of your 3D survey grid. The Cross Section window displays a vertical cross section through the current velocity volume at the position of the heavy, gray line 8-16


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that appears in the Map window. You can quickly change to a vertical cross section oriented 90 degrees to the current Cross Section display by clicking on the “Select the perpendicular slice” icon. Clicking MB1 will alternately display perpendicular vertical cross sections at the position of your cursor. 5. From the Cross Section window, click View

Volume Display.

A “Volume Controls” window will appear. Click the Cross-section Nodes and Map Nodes, then Ok. This will display symbols in the Map window and vertical lines in the Cross Section window indicating the positions of the Velocity Analysis centers already saved to the velocity table. The locations of these symbols and lines are referred to as nodes. You should also set the maximum node projection distance to about 5 (inlines or crosslines). This will ensure that the vertical display only shows picked velocity locations that are within 5 inlines (or crosslines) of the vertical slice. 6. In the Velocity Analysis window, pick or modify the velocity function for the current location. In the Velocity Analysis display, click on the “bow-and-arrow” icon to send the information to the Volume Viewer/Editor. The velocity displayed in Volume Viewer/Editor updates in response to picks made in Velocity Analysis. You should now see a vertical line in the Cross Section window and a circular symbol in the Map window at the X, Y location of the velocity function just picked. 7. In the Velocity Analysis window, click on the “Process next ensemble” icon, and pick the next analysis location. When you are finished picking this new analysis location, click on the “Process next ensemble” icon again. This will not only move you to the next analysis location, but will automatically send the velocity picks just made to the Volume Viewer/Editor displays. You should now have many symbols/lines in the Map and Cross Section windows. Your velocity field should also have changed color slightly based on the velocity changes just added.

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Velocity Analysis PD Tool: By activating this icon, you can select a CDP and send it to Velocity Analysis. This icon does not appear if No was selected for “Interact with Velocity Analysis?” in the Velocity Viewer/Editor menu. Any Velocity Analysis CDP location can be easily retrieved or deleted from Volume Viewer/Editor through the use of the mouse. This allows random access to any of the precomputed and picked locations. 8. In either the Map window or the Cross Section window, click on the “PD” icon. With the “PD” icon activated, position the mouse cursor over a node. The cursor should change from an “x” to an “o”. Click MB1 to retrieve that velocity function into the Velocity Analysis display. Clicking MB2 deletes that analysis location. 9. Continue picking velocities in Velocity Analysis until you finish all of the locations for this project. Remember, you may either use the “bow-and-arrow” icon to send the picks from Velocity Analysis to the Volume Viewer/Editor displays for QC before moving to the next analysis location, or you may move directly to the next ensemble and your previous picks will be automatically sent to the Volume Viewer/Editor displays. 10. To finish picking in Velocity Analysis, click on the File Exit/ Stop Flow pull down menu in the velocity analysis and the File Exit pull down in the Volume viewer.

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Chapter 9

3D Dip Moveout 3D Dip Moveout (DMO) is a dip-dependent partial migration that transforms nonzero-offset seismic data into zero-offset seismic data. This yields improved (dip independent) velocity estimates, attenuates coherent noise, and improves lateral resolution. In this chapter we discuss how to run the modules DMO to Gathers 3D and DMO to Stack 3D.


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Offset Binning Parameter QC

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DMO to Gathers 3D

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Chapter 9: 3D Dip Moveout

Offset Binning Parameter QC DMO to Gathers 3D outputs offset binned data. This offset binning is declared in the DMO to Gathers menu; therefore, the proposed parameters must be checked before running the DMO process. Ideally, our input data has perfect offset distribution that allows each offset bin to be single fold with no gaps or holes in coverage. The number of offset bins would be equal to the CDP fold. Conventional data collection methods do not accommodate this "perfect world", especially for land data. In this exercise, you will examine offset distributions using the 3D display capabilities in the database and choose optimal offset parameterization for the output DMO gathers. Examine the Offset Binning Problem This exercise will use a database display to examine offset distribution for our CDP gathers.

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1. Open DBTools, and generate the following 2D matrix from the TRC domain: 2D Matrix (TRC); CDP_X, CDP_Y, OFFSET, OFFSET.

For DMO, it is preferable that each CDP have a relatively uniform distribution of offsets. Alternatively, you can think of this as having at least one "live" trace at every CDP within a given offset range. Most surveys will need some form of offset binning to ensure an adequate distribution of offsets in the CDP gathers. The following steps examine this problem in a qualitative manner on the Salt3D dataset.

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2. Select one offset range near 1000 ft. from the histogram.

Notice that this particular offset range is present in many of the CDPs, but not all of them.

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3. Select a single offset range near 12,000 ft. from the histogram.

Notice that this offset range is missing from many of the CDPs. 4. Experiment by selecting 2, 3, and 4 consecutive offset ranges from the histogram. How many ranges are needed in an offset bin to have adequate offset distribution? The next exercise will explore this question with a more quantitative approach. Offset Binning Parameter Determination 1. From the XDB Database, generate a 3D:XYGRAPH from the TRC OPF of OFFSET, CDP, ILN. This graph will show you the offset distribution of your entire 3D dataset. It can be used to help you determine an appropriate number Landmark


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of bins, and minimum and maximum offset. You can use these values when selecting DMO to Gathers 3D parameters. 2. Change the color table to use the table called “contrast.rgb” using the Color Edit and File Open pull down menus. 3. Zoom in and display 2 lines on the screen. Typically for land 3d surveys this analysis should be done on more than one line.

offset bin width?

Offset vs. CDP plot for 2 lines From this plot we need to determine how wide the offset bins need to be to get good population in the offset volumes. Remember that our goal is to get at least 1 trace per CDP per offset bin.

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You can overlay a grid on this display, resize the bins to your proposed DMO offset bin width to start analyzing the data for proper bin width determination. 4. Click on the Grid

Display pull down menu.

Nothing much happens except that the bin editing icons appear on the left side of the screen, out of your zoom window. 5. Click on the Grid

Parametrize pull down menu.

A small dialog box will appear where you can change the characteristics of the grid.

76800

6. Change the value of the Y origin to a value near the bottom of your zoomed window. In this example we can set it to 76800 as shown in the previous diagram. 7. Click on the Green Light Icon.

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You should get some lines drawn on the XYgraph.

grid lines

zoom window

8. Zoom in on one line.

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How wide does the offset bin need to be to get 1 trace per CDP?

measure the “half diamond” distance

Half Diamond Explanation Here we must decide on the offset bin width. One way to do this is to measure the “half diamond” distance using the “double fold” icon MB3 function. You should measure values around 600 ft. Given our group interval is 165 ft. Let’s try an offset bin width of 660 ft (4*165). and see what results we get. i.e. how many offset bins and population in the bins. 9. Click on the Grid

Parametrize pull down menu.

Set the Cell Size across Azimuth to 660 ft. and press the green light icon.

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10. Move the Grid with so that the edge of the first bin is near the left edge of the offset range, and add enough cells to cover all offsets. Looking at these offset bins, we have reasonable coverage within most of the offsets, and only the far offset volumes are sparsely populated. This should give reasonable results for the DMO to gathers exercise.

1 2 3 4

22 23

23 Offset Bins of 660 ft each

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11. Zoom in on the first offset range, and center the first bin on the offset range as shown below.

Measure the offset of the near edge of the first bin Center the edge of the first bin between these offset ranges.

Centering the first offset bin 12. Place you cursor on the near edge of the first bin, and read the offset. It should be between 200 and 220 ft. 13. Repeat the above exercise to measure the far offset of the last bin. The minimum offset, maximum offset, offset bin width and number of bins are the parameters that we need for DMO to Gathers 3D.

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DMO to Gathers 3D DMO to Gathers 3D is a constant velocity DMO process that accumulates the DMO response of each trace in a partial stack indexed by CDP, inline location, crossline location, and offset. This process uses an Integral (Kirchhoff) method with care taken to avoid spatial aliasing of the DMO operator. There are many different paths that you can take here. There are also many questions that need to be answered: Which velocity lines do you want to resolve in this job? •

Lines 50-250(50)

Do you want to do spatial supergathers or inline supergathers? •

Inline supergathers

Are you running on an SMP machine and do you need to parallelize the pre-processing as well as the DMO? •

This will vary depending on the machines and network available where the training class is being taught.

Have you adequately allocated scratch space? •

We should have enough scratch allocated to output 5 lines of 390 crosslines and 23 traces per CDP.

Are you going to parallelize the DMO? •

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No parallelization will be used (depends on available hardware at the class site).


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1. Build the following flow to run DMO to Gathers 3D: Editing Flow: 23- DMO to Gathers Add

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Disk Data Input Select dataset ----------------------------------- shots - pre-processed Trace read option ----------------------------------------------- Get All

Apply Residual Statics Normal database entry naming mode?----------------------------Yes Type of residual statics to apply-----------Max. Power Autostatics

Normal Moveout Correction Direction for NMO application ------------------------- FORWARD Stretch mute percentage ---------------------------------------------- 0. Apply any remaining static during NMO?------------------------Yes SELECT Velocity parameter file ----------- after resid stat b4 dmo

Trace Muting SELECT mute parameter file -------------------- post-NMO (brute)

DMO to Gathers 3D Trace Display Label Disk Data Output 2. In Disk Data Input, input the shot organized files with preprocessing applied. 3. Apply the residual statics that were generated by the Max. Power Autostatics process.

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4. In Normal Moveout Correction, select the best RMS velocity field. Editing Flow: 23- DMO to Gathers (cont) Add

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DMO to Gathers 3D Enter name of host ----------------------------Number of worker threads---------------------------------------------1 Minimum in-line number---------------------------------------------50 Maximum in-line number -------------------------------------------250 in-line number output sampling interval ---------------------------50 Minimum x-line number -----------------------------------------------1 Maximum x-line number -------------------------------------------390 x-line number output sampling interval -----------------------------1 number of consecutive gathers to output at each location---------1 Typical CDP interval: average inline and crossline------------82.5 Minimum offset to retain -------------------------------------------215 Maximum offset to retain ----------------------------------------15395 Number of offset bins -------------------------------------------------23 Offset sampling ------------------------------------------------OFFSET Typical maximum offset in dataset for antialias-------------15500 Typical mute time at largest offset -------------------------------1600 Typical RMS velocity at early times -----------------------------6000 Apply v(z) correction?------------------------------------------------no Amplitude and phase balancing mode--------------exponent of fold Exponent of normalization factor ----------------------------------0.5 Max. number of amp or phase normalizations per trace------- 100 Re-kill dead traces and apply stack mutes?-----------------------Yes Size of input trace memory buffer (MB)----------------------------16 Size of stack trace memory buffer (MB) ----------------------------16

Trace Display Label Disk Data Output 5. Apply the post NMO mute. 6. Select the DMO to Gathers parameters.

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In DMO to Gathers 3D, leave host name blank. Host name refers to the name of the hosts, or nodes, where you would like to run the program. This program is set up to run in parallel (on more than one machine). If no host name is specified, the process executes on the same node as the ProMAX executive. Make the crossline number sampling interval 1 and the inline number sampling interval increment by a sampling interval for performing velocity analysis. In this case, use 50 to output every fiftieth inline starting at 50 and ending at 250. 7. Set the CDP spacing to 82.5 ft. 8. Set the number of offset bins to 23 and the offset range to start at 215 ft. and end at 15395 ft. The number of offset bins parameter governs the number of output traces per CDP. 9. Values of 1600 ms mute time at far offset and 6000 ft./sec shallow velocity is satisfactory. 10. Specify 100 for the number of amplitude and/or normalization scalers per trace. 11. Default the size of memory buffers. 12. Add a Trace Display Label and Disk Data Output to label and output the data after the DMO. This output data can be stacked for an intermediate product to QC the DMO process. This data would also be the input to the next iteration of Velocity analysis. Remember to remove the NMO that has been applied prior to running another velocity analysis. 13. Execute the flow.

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14. For this exercise, we will not be using the output data. You may elect to QC the output data by running a quick flow to display a few CDP ensembles.

Notice that all CDPs after DMO to Gathers have the same offset distribution. This poses a couple of questions:

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•

What are the proper parameters for minimum offset, maximum offset and offset increment in the Velocity Analysis Programs?

•

How do you decide on a super-gather for velocity analysis? Offset distribution is no longer an issue.


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DMO Stack 3D DMO Stack 3D is a constant velocity DMO process that accumulates the DMO response of each trace in a stack indexed by CDP, inline, and crossline location. Like DMO to Gathers 3D, this process uses an Integral (Kirchhoff) method, with care taken to avoid spatial aliasing of the DMO operator. Unlike DMO to Gathers 3D, DMO Stack 3D stacks all offsets into a zero-offset stack trace. To compensate for variations in coverage, the process maintains timedependent fold information for each stack trace, and scales each stack trace by that fold. The fold information is maintained in the stack trace headers and can be accessed by other processes. If the DMO was to be run in parallel on an SMP type machine you may want to also parallelize the pre-processing as well. If the pre-processing is not parallelized, the DMO may not run efficiently because it will be waiting for traces to come down the “pipe”. Parallelizing the preprocessing may help the “pipe” keep up DMO’s demand for traces. The alternative would be to run the pre-processing in a separate flow and output a new pre-stack dataset. This dataset would then be read into the DMO flow.

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1. Build the following flow: You might want to copy your DMO to Gathers flow to make this flow: Editing Flow: 24- DMO stack Add

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Disk Data Input Select dataset ---------------------------------- shots - Pre-processed Trace read option ----------------------------------------------- Get All

Apply Residual Statics Normal database entry naming mode?--------------------------- Yes Type of residual statics to apply-----------Max. Power Autostatics

Normal Moveout Correction Direction for NMO application ------------------------- FORWARD Stretch mute percentage ---------------------------------------------- 0. Apply any remaining static during NMO?------------------------Yes SELECT Velocity parameter file ----------after resid stat b4 DMO

Trace Muting SELECT mute parameter file ---------------- post nmo mute (brute)

Automatic Gain Control DMO Stack 3D Trace Display Label Disk Data Output 2. In Disk Data Input, input your shot organized data with preprocessing applied. 3. Apply the residual statics that were generated by the Max. Power Autostatics process. 4. In Normal Moveout Correction, enter the best, current RMS velocity field. Here we would normally use the velocities that were picked using the data that was output from the Dmo to Gathers 3D process. We did not run these velocities so you can use one of the other tables. 5. Apply the post NMO mute.

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6. The flow as described shows an Automatic Gain Control, you can toggle this processes active. The output from the Stack DMO process is more aesthetically appealing (on this dataset) if you apply an AGC, or other scaling function, prior to the DMO process, although it is not required. 7. Select DMO Stack 3D parameters. Host name refers to the name of the nodes where you would like to run the program. This program is set up to run in parallel (on more than one machine). If no host name is specified, the process executes on the same host as the ProMAX executive. 8. Leave the restart parameter defaulted to No. The restart parameter allows you to alter an existing 3D DMO stack with the DMO stack response from another prestack dataset. 9. Specify your minimum and maximum inline and crossline numbers to include the entire dataset. 10. Set the CDP spacing to 82.5 ft. 11. Set the estimated maximum offset to 15000 ft., and the mute time at the largest offset to 1600 ms. The estimated maximum offset parameter and the typical mute time at largest offset parameter are used to determine the number of time shifts required in the DMO operator A shallow velocity of 6000 ft./sec is satisfactory. 12. Set the exponent of fold normalization scalers to 0.5. The exponent of fold normalization scalers will divide each stack trace by the fold normalization scaler to this power. A value of 0.5 is

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recommended for noisy data, while 1 is recommended for synthetic data. Editing Flow: 24- DMO stack (cont) Add

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Disk Data Input Apply Residual Statics Normal Moveout Correction Trace Muting Automatic Gain Control DMO Stack 3D Enter name of host ----------------------------Number of worker threads--------------------------------------------1 Restart with an existing stack? -------------------------------------No Minimum in-line number ----------------------------------------------1 Maximum x-line number --------------------------------------------308 Minimum X-line number-----------------------------------------------1 Maximum in-line number -------------------------------------------390 Typical CDP spacing in ensembles-------------------------------82.5 Maximum offset to retain ----------------------------------------15000 Typical mute time at largest offset -------------------------------1600 Typical RMS velocity at early times -----------------------------6000 Apply v(z) correction?------------------------------------------------No Amplitude and phase balancing mode--------------exponent of fold Exponent of normalization factor ----------------------------------0.5 Max. number of amp or phase normalizations per trace------- 100 Apply final datum statics after stack?------------------------------Yes Re-kill dead traces and apply stack mutes?-----------------------Yes Size of input trace memory buffer (MB)----------------------------16 Size of stack trace memory buffer (MB) ----------------------------16

Trace Display Label Trace label --------------------------------------------------DMO stack

Disk Data Output Output Dataset Filename --------------------------Stack - with DMO

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The number of fold normalization scalars parameter controls the time interval for which a record of the time-variant fold at each CDP is maintained. Greater numbers for this parameter preserves relative amplitude and phase better, but makes the program run very slightly longer. These scalars are retained in the output trace headers, and are used with the restart option or when merging datasets with Stack Merge 3D. 13. Apply the CDP mean static (final datum static). 14. Set the rekill and mute apply switch to Yes. This is one parameter that will generally need to be tested. As a general rule set this to YES especially if fully resolved output is being generated. If you detect shallow amplitude anomalies you may find that setting this to NO will help. When working in a partial stack and stack merge sequence you will generally want to set this to NO and then rekill and remute after the stack merge. 15. Set the size of memory buffers to 16 MB. The size of memory buffers has negligible effect on performance. 16. In Trace Display Label, label the dataset as being a stack after DMO. 17. In Disk Data Output, output a dataset for a stacked after DMO dataset. 18. Execute the flow. 19. Compare the DMO stack with previous stacks using your stack comparison flows.

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Chapter 10

CDP Taper on Stack Data CDP Taper is a post stack, premigration amplitude tapering tool that, as well as modifying the seismic data amplitudes, stores the scalar values in the CDP GEOMETRY Ordered Parameter Files as the TOPTAPER and BOTTAPER parameters. The top and bottom taper numbers define an amplitude ramp that is applied to each trace in the flow.


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CDP Taper Overview

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Execution of CDP Taper

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Generating QC Plots of the Taper Values


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Chapter 10: CDP Taper on Stack Data

CDP Taper Overview In most cases you will want to apply some amplitude tapering to the edge traces of a 3D prospect prior to 3D migration. Tapering does exist in most of the migration programs, but this taper is relative to the padded edges of a rectangle surrounding survey. In cases where the line ends are not constant you may still end up with amplitude discontinuities from line to line or crossline to crossline. The CDP Taper program computes a smoother amplitude scaler for the edge traces based on user specified search window sizes. The higher value of search window that is input, the more tapering will be applied. For 3D, this tool scans the CDP fold over a moving rectangular array of user defined size, computing top and bottom taper numbers for the center CDP in the array.

live in the corner

on the edge one line in from the edge dead in the corner

first live, but not on the edge CDP Taper Example Locations 10-2


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The actual value used at a trace is the taper value * the amplitude. If there are no zero fold CDPs in the array, the taper value is 1. If there are zero fold CDPs in the array and the center CDP has non-zero fold, the taper number is calculated as:

Using Equation

INT(array area/2) - number of zero fold CDPs INT(array area/2). Center CDP is on the edge (first/last line or first/last xline) Taper value = 0 If CDP not on the edge then Total number of CDP’s in window = 25 Total number of zero fold CDP’s = 10 Taper value = (12-10)/12 = 0.17 Center CDP has fold >0 Total number of CDP’s in window = 25 Total number of zero fold CDP’s = 5 Taper value = (12-5)/12 = 0.58

Center CDP has fold = 0 Taper Value = 0

Center CDP has fold > 0 Total number of CDP’s in window = 25 Total number of zero fold CDP’s = 6 Taper Value = (12-6)/12 = 0.50

Examples of Taper Calculation If the center CDP is on a dataset edge, the fold of the center CDP is zero, or the number of zero fold CDPs is greater than half the array area, the taper number is 0.

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Execution of CDP Taper In this exercise, we will build a CDP Taper flow and apply the tapers to the stack data and QC the results on the traces and in the database. 1. Build the following flow: Editing Flow: 25 - cdp taper Add

Delete

Execute

View

Exit

Disk Data Input Select dataset ---------------------------------------Stack - with DMO Trace read option ----------------------------------------------- Get All

CDP Taper Mode -----------------------------------------------Compute and Apply Top number of inline CDP’s ----------------------------------------- 5 Top number of cross line CDP’s--------------------------------------5 Bottom number of inline CDP’s---------------------------------------9 Bottom number of cross line CDP’s----------------------------------9 Apply or remove taper --------------------------------------------Apply

Trace Display Label Trace label -----------------------------------------DMO stack (taper)

Disk Data Output Output Dataset Filename-------------------Stack - DMO and Taper 2. In Disk Data Input, input a previously created file that is a stack data set. This should be the DMO stack. 3. The CDP Taper process has 6 parameters. In this example we will use a 5 x 5 CDP operator at time zero and a 9 x 9 CDP operator at the maximum time of the input data. 4. Output a new stack file using Disk Data Output. 5. Execute the flow.

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6. Look at the output data file compared to the input using the “compare inlines” flow that we already have available. Make sure that you turn off the AGC or you will remove the effect of the taper. You will also want to set the trace scaling in Trace Display to Entire Screen instead of Individual since the individual scaling will also partially remove the effects of the tapering. 7. With these parameters it will be difficult to see much difference since we essentially have a two trace taper shallow and a 4 trace taper at maximum time. NOTE: Notice that the first and last lines are completely dead after the CDP Taper. This is the expected behavior. For this reason you may elect to pad the CDP grid by one CDP in all directions since CDP Taper will kill any trace on the first and last inline and cross line of the project.

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Generating QC Plots of the Taper Values The CDP Taper process writes two sets of numbers to the CDP database. A single value is output for the top taper value for each CDP and for the Bottom taper. We can use the database display tools to visualize how the taper varies in space. QC Plots from DBTools 1. Open the database. 2. Select your area, line, and the CDP order. 3. Display a 2D Matrix of CDP: X, Y, FOLD. (Select Color Edit and then File Open to reset your colormap to default.rgb if necessary.) 4. Display a 2D Matrix of CDP: X, Y, TOPTAPER,TOPTAPER. 5. Display a 2D Matrix of CDP: X, Y, BOTTAPER, BOTTAPER. 6. Edit the Colorbar. Set the interpolation mode to “MANUAL” and the change the color of the first color box to black. Here you can clearly see the original zero fold CDP’s in the fold plot and you can see the traces which have been assigned a taper scaler of zero. Try other values for TOPTAPER and BOTTAPER Rerun the flow using values of 11 and 21 for the top and bottom tapers and regenerate the QC plots. You might need to open the database again to display the new values properly.

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Chapter 11

3D Velocity Viewer/Editor This stand-alone tool enables you to scan through a 3D velocity field, identify and edit velocity control points, and analyze the interpolation between the control points. This tool also lets you smooth the velocity field and convert stacking velocities to interval velocities. A typical use of this tool is to analyze velocities for anomalous points that you may want to edit. In particular, bad velocities are frequently created when converting stacking velocities to interval velocities. This tool ensures that a reasonable velocity field is being passed to migration. This tool differs significantly from the Interactive Velocity Editor (IVE). IVE is designed to create/edit a fine 2D grid of points, while looking at a stack section overlay. In contrast, this tool allows you edit the sparse control points that define a 3D velocity field.


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3D Velocity Viewer/Editor Overview

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3D Velocity Viewer/Editor Execution


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Chapter 11: 3D Velocity Viewer/Editor

3D Velocity Viewer/Editor Overview The following figures are included to help guide you through the tool. Inline view of velocity field Pulldown menus

Last crossline location

Locations of velocity functions near the viewing plane Last time slice location

Icon Bar •

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Zoom: Enables zooming of the velocity field.


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•

Move: Move view forward and back or up and down. Also used to flip to an inline view when in a crossline view and visa-versa.

•

Rotate: Rotate to an inline, crossline, or time slice view.

•

Edit vel function: Popup another screen to display and edit a selected velocity function.

•

Display Vel Scale: Display a simple velocity scale.

Time Slice View

Circles represent location of the velocity functions. Black lines indicates triangulation for spatial interpolation of velocity functions. Solid white lines mark last displayed inline and crossline views. Dashed white lines

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mark width of zone used to mark nearby velocity functions on the axis of an inline or crossline view. 3D Table Triangulation The above time slice view shows the triangulation used for spatial interpolation by ProMAX tables. After values in a table are interpolated vertically in time or depth, they are interpolated spatially using the 3 vertexes of the triangle that encloses the location to interpolate. The triangulation of the function locations is defined via the Delaunay approach that produces the most equilateral triangles possible.

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3D Velocity Viewer/Editor Execution This exercise instructs you on parameter selection and execution of the 3D Velocity Viewer/Editor. We will input one of the RMS stacking fields that we have and output two new velocity tables: one for FK migration and another Interval Velocity field for Phase Shift migration. Select the 3D Velocity Viewer Parameters 1. Build the following flow: Editing Flow: 26 - vel condition for mig Add

Delete

Execute

View

Exit

3D Velocity Viewer/Editor* Select the type of field to edit ------------------- Stacking (RMS) vel Do you wish to edit an existing table ------------------------------ yes Select input velocity--------------------------- after resid stat b4 dmo Minimum inline coordinate of viewing box--------------------------1 Maximum inline coordinate of viewing box ----------------------308 Minimum crossline coordinate of viewing box----------------------1 Maximum crossline coordinate of viewing box------------------390 Select output velocity database ---------------- smoothed for fk mig Specify and alternative name of output INTVEL ---------------- Yes Select output Interval velocity ------------------- for phase shift mig Minimum depth (or time) ----------------------------------------------0 maximum depth (or time) ----------------------------------------------0 2. Input one of the RMS velocity fields that are available. If you did not complete the velocity field picking you may use the original field that we imported from the ASCII file. 3. Specify an output name for the edited RMS field. 4. Enter an alternative name for the output interval velocity table.

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We will output two tables from this program. One edited and smoothed in preparation for FK Migration and another that is an Interval Velocity as a function of time for phase Shift 3D Migration. 5. Execute the flow. Edit and Smooth the RMS Velocity for FK Migration 1. Click on the Edit Icon and move the cursor into the display area. The screen will adjust to have two windows. On the left is the velocity contour and on the right is the velocity function edit window. Edit velocity function window

Edit Icon

Location of velocity function being edited

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Location of additional velocity function used as reference for plot on right side.


Velocity function being edited (circles mark control points)

Additional function used as reference

Conversion of velocity being edited to interval velocity (two different conversion methods are being used)

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Icon Bar •

Zoom: Enables zooming of the velocity field.

•

Picking Tool: Edit velocity points.

Editing velocities The Edit velocity function window will contain the function nearest to your mouse location, The right hand window shows the location of the selected functions control points with red circles. The mouse pointing help at the bottom of the screen guides your mouse motions. MB1: Edits the nearest velocity function. This edit function will appear in the right window in red. As you move your mouse, the blue function will still reflect the function nearest to your mouse location. In this way, you can compare two functions. To freeze a blue function you can use MB2. Move your mouse to the right window and activate the Edit Function Icon. This lets you add/move/delete the red function locations marked by the circles. Use the mouse button helps at the bottom of the screen as a guide. MB3: Delete all points at a function location, and hence delete the function. Shift MB1: Adds a new function at a certain location. Another way to think of this is to Freeze the blue curve on a function that you like with MB2 and edit the questionable function with MB1. When you press UPDATE with your new velocity function, you will see its effect on the entire velocity field. If you don’t like your changes, use the Modify/Undo button to remove the old function.

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2. Select a function to edit with MB1, and then activate the "Picking" icon.

3

1

2

3. Use MB1 to add a bogus value to the velocity function and then press update.

2

1

4. Select Modify

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Undo last change to remove the bad edit.


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5. Use the Rotate icon along with the mouse button helps to move from line to line and change the display from inlines, crosslines and time slices. Hand edit the major discontinuities. Velocity Field Gridding and Smoothing 1. Select the Modify Smooth Velocity field pull down menu to smooth the RMS velocity field.

The first two entries ask about the sampling of the new smoothed field. We can enter values that are the same as our input field. • •

Crossline Sampling Interval = 50 Inline Sampling Interval = 50

The time sampling is up to the processor and how complex the velocity field is as a function of time. Our field is fairly well behaved with no inversions and a relatively linear increase as a function of time. We can resample our field at 200 msec intervals without any problems. • Landmark

Time Sampling Interval = 200 ms ProMAX Seismic Processing and Analysis

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The smoothing parameters are also up for interpretation. Normally, you would measure the anomaly size (in CDPs) that you want to smooth through on the inline or crossline displays and input these values. For our purposes values around 20 inline and crosslines with about 200 msec of smoothing should be adequate. • • •

Crossline smoothing Operator Length = 50 Inline Smoothing Operator Length = 50 Time Smoothing Operator Length = 250

2. Click OK. 3. Review the smoothing operation by looking at inlines, crosslines and time slices. 4. If the smoother was too harsh you can use the Modify Undo last change pull down, reset the parameters and repeat the process until satisfied. 5. Save this velocity field to disk using the File disk pull down menu.

Save table to

Convert to Interval Velocity 1. Select the Modify down menu.

Convert RMS to Interval Velocity pull

There are two choices, Constant Velocity Dix or a Smoothed Gradient Dix conversion. For our purposes in making and interval velocity vs. time function we will choose the Smoothed Gradient method. 2. Review some inlines, crosslines and time slices after the conversion and see if any additional smoothing or editing is required. You may want to smooth the volume again using the same parameters as before, but increasing the time smoother to 500 msec. 3. Use the File Save table to disk and exit pull down menu to save this table to disk and exit the program. We now have two velocity fields:

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•

A smoothed RMS field for FK migration and

•

A smoothed Interval Velocity field for Phase Shift 3D migration.


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Chapter 12

Migration The ProMAX 3D suite of migration tools includes poststack time and depth migration algorithms. The available migrations are F-K, Finite Difference (FD), and Phase Shift. The goal is to migrate the stack section with the most appropriate migration process. To aid in this selection, this chapter includes a brief description of the processes. The Online Manual and references give further detail.


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3D Migration Summary

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3D Migration Exercise


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Chapter 12: Migration

3D Migration Summary The choice of poststack migration process can be difficult. You must weigh CPU time, accuracy of the velocity model, steepness of dip to be imaged, and other factors in choosing the most appropriate process. Often, a number of different migrations must be run in order to compare results. To help you decide on the optimal migration for a given situation, the migrations are summarized. Dip

Rel. Time

Poor

Poor

0.9

VINT(x,y,t) None

Good

Good

1

VINT(x,y,z) Fair

Good

Good

5

Migration Name

Type

Domain Velocity

V(x,y) V(t/z)

Stolt 3D

F-K

Time

VRMS(x,y,t) Poor

Phase Shift 3D

Phase Shift Time

PSPC 3D Depth

Phase Shift Depth

Explicit FD 3D Time F-D

Time

VINT(x,y,t) Fair

Good

Good

13

Explicit FD 3D Depth F-D

Depth

VINT(x,y,z) Good

Good

Good

18

Some of the 3D migrations provide two important restart options. The first option is activated by choosing to checkpoint the process, which will regularly save migration workfiles to disk. In caset your migration process is abnormally terminated, the migration can be restarted from the last checkpoint. The second option is activated by choosing to save data at a specific depth for restart. In this case, data may be migrated down through the current, reliable velocity information and then subsequently be continued with new velocity information below. Data input to these migrations must be corrected to a flat datum. If your data is referenced to a floating datum, you will need to complete the application of datum statics to move your data to a flat datum. If your velocity field is referenced to a floating datum, you can modify the velocity field with Velocity Manipulation. Also, the stacked data must be sorted with the primary sort of inline and the secondary sort of crossline. Use the Pad 3d Stack Volume process to pad the stacked data using ILINE_NO as the primary sort. The padded traces should be sorted with the primary sort of inline and the secondary sort of crossline. With all 3D Migrations, you should be aware of the potential need for extended scratch space. How much scratch space a particular migration

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will use may be determined in the View file. When running 3D Migrations in parallel, certain conventions should be followed for naming scratch space on these machines. Refer to the Extended Scratch Space section in the System Administration online help for a complete description of the extended scratch space setup and requirements. Stolt 3D Migration Stolt migration is computationally efficient, but has difficulty imaging steep dips in areas where there are large horizontal and vertical velocity variations. This algorithm uses Stolt’s (1978) stretching technique to account for horizontal and vertical velocity variations. The F-K process requires RMS velocities as input and migrates common offset or stacked data. It is the fastest migration algorithm in ProMAX. Velocity variations are compensated for via the Stolt stretch. This algorithm does not accurately handle strong vertical or horizontal velocity variations. Phase Shift Migration The Phase Shift migration process uses an interval velocity vs. time field. It can migrate dips greater than 90 degrees (turning rays) and, unlike the 2D equivalent, this 3D migration can handle lateral velocity variations to a limited extent utilizing a modified stretching technique. The primary advantages of this approach are speed and accurate handling of high dips. PSPC 3D Depth Migration The PSPC Depth migration process uses a spatially-variant interval velocity function in time, VINT(x,y,t). Vertical velocity variations are handled very well by this algorithm. Spatial velocity variations are accommodated with a first-order phase correction, applied to phaseshift migrated data. A phase-shift interpolation option is included for increased accuracy. With this option, the first-order phase correction is applied to the migrated data corresponding to the closest approximation to the required velocity value. The primary advantages of this approach are relative speed, accurate handling of high dips, and good compensation for spatial velocity variations. Explicit FD 3D Time Migration This algorithm uses explicit F-XY spatially-variant extrapolators to perform time migration. This migration is designed to be accurate up to

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approximately 70 degrees of dip. This migration uses a vertical and spatially-variant interval velocity field in time, VINT(x,y,t), for input. To reduce run times for this algorithm you may specify a maximum dip of either 30 or 50 degrees, rather than the default of 70 degrees. Run times are dependent upon the maximum frequency for migration, so choose this value accordingly. A further option to enhance performance is to select the Split option, for two-pass migration, instead of the Full 3D option, for one-pass migration. Explicit FD 3D Depth Migration This is an algorithm which uses explicit F-XY spatially-variant extrapolators to perform 3D depth migration. This migration is designed to be accurate up to approximately 70 degrees of dip. This migration uses a vertical and spatially-variant interval velocity field in depth, VINT(x,y,z), for input. You can choose from 30, 50, and 70 degree options of which the higher maximum dip angles have longer run times. A further option to enhance performance is to select the Split option, for two-pass migration, over the Full 3D option, for one-pass migration. The primary advantages of this approach are efficiency and good handling of vertically-variant velocities and moderate dips, and fair handling of spatial velocity variations. Trace padding should be specified to reduce wrap-around effects in the frequency domain. Values in the range of 30 to 50 percent are generally adequate for normal amplitude-balanced datasets. Explicit FD 3D migration requires the trace spacing of the input data to be equal in the inline and crossline directions. If this is not the case in your 3D survey, use one of the trace interpolation techniques available in ProMAX. Create a new line and run 3D Poststack Geometry on the interpolated dataset to create a CDP database and have the appropriate trace spacings entered in the LIN database.

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Re-datum Velocities to Flat Datum As mentioned in the earlier discussion, you may want to adjust the times of you velocity functions, which are referenced to floating datum, to be referenced to the flat reference datum to match the time of the stack data. This can be accomplished very easily using the Velocity Manipulation process. Re-datum the Interval Velocities 1. Build the following flow. Editing Flow: 27- redatum velocities Add

Delete

Execute

View

Exit

Velocity Manipulation* Type of velocity table to input ------------------ Interval Vel in Time Get velocity table from database? ---------------------------------Yes Select input velocity database entry ------------ for phase shift mig Combine a second velocity table with the first ------------------- No Resample the input velocity table(s)? ------------------------------No Shift or stretch the input velocity table?--------------------------- No Adjust the velocities to final datum ------------------------------- Yes Type of parameter table to output ------------------- Int Vel in Time Select output velocity database entry -------- for ps mig - at datum Output a single average velocity table? -------------------------- No Vertically resample the output velocity table? ------------------- No Adjust output velocities by percentages? ------------------------- No Clip output velocities?------------------------------------------------No

3D Velocity Viewer/Editor Select the type of field to edit - Interval Velocity in Time Select input velocity database entry ---------- for ps mig - at datum 2. Execute the flow. You may elect to view the input and output fields using the 3D Velocity Viewer/ Editor Program.

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3D Migration Exercise 1. Build the following flow. Editing Flow: 28- migration - phase shift Add

Delete

Execute

View

Exit

Disk Data Input Select dataset --------------------------------Stack - DMO and Taper Trace read option ----------------------SORT - ILINE x XLINE *:*/

Stolt or Phase Shift 3D Migration Name of migration server host(s) ---------Number of migration server nodes------------------------------------1 Migration algorithm----------------------------------------Phase Shift Migrate, Demigrate or Inverse Migrate--------Migrate input data Migration of dips---------------------------Up to 90 degrees only Select interval velocity file -------------------- for ps mig - at datum Minimum/maximum in-line numbers --------------------------1/ 308 Minimum/maximum x-line numbers--------------------------- 1/ 390 Output trace length-----------------------------------------------------0 Output sampling interval --------------------------------------------- 0 Minimum frequency to migrate ---------------------------------------0 Maximum frequency to migrate -------------------------------------60 Number of in-line traces to pad ---------------------------------------0 Number of cross-line traces to pad -----------------------------------0 In-line taper length (in traces) --------------------------------------- 0 Cross-line taper length (in traces) ----------------------------------- 0 Top time taper (in ms) ---------------------------------------------- 100 Bottom time taper (in ms) ------------------------------------------ 100 -----------Default all remaining parameters-------------

Trace Display Label Trace label --------------------------------------------mig - phase shift

Disk Data Output Output Dataset Filename----------------------------Mig - phase shift

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2. In Disk Data Input, input the stack dataset after DMO and CDP Taper. 3. Select the Phase Shift Migration parameters. 4. Select the Interval Velocity vs. Time function shifted to final datum that we generated specifically for Phase Shift migration using the velocity editor. 5. Set the frequency range to start at 0 and go to 60 Hz. This is a reasonable range for this dataset. You can improve the performance of the migration by reducing the frequency range. 6. Leave the pad parameters at 0 traces. Normally you would want to compute the migration aperture and add enough traces to prevent the energy from wrapping from one side of the stack to the other. In this case, we are just interested in getting the flow to quickly run. So you can expect to see some spatial wrap on the output section. 7. Set the top taper to 100 ms and the bottom taper to 100 ms. Since you have applied the AGC prior to the Stack DMO, our dataset is fairly well modulated in amplitude and you do not require long tapers. 8. Re-apply the original mutes and rekill all traces that were originally dead. 9. In Trace Display Label, label your dataset. 10. In Disk Data Output, output your dataset. 11. Execute the flow. 12. When complete, you have a new stack volume. You can compare this volume to previous volumes using the display comparison flows that were built earlier. NOTE:

Make sure your $PROMAX_HOME/etc/pvmhosts file is set up correctly. This is the first thing to check if the migrations fail to run.

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Promax Manual

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