Using GLOBE Claritas. 2D/3D Seismic Processing Software

Transcription

1 Using GLOBE Claritas 2D/3D Seismic Processing Software June 2008

2 GLOBE Claritas : Concept Created as a processing environment Designed to fit around your workflows and practices No un-wieldy database or forced data structures Simple ASCII text or modified SEGY file formats Easily linked to third party software Designed to support code and methodology development Flexible : handles data from GPR to earthquake scale Site licensed : multiple machines, clusters or CPU types

3 Getting Started : Launcher Type launcher at the prompt Access to all Claritas tools and utilities Optional : all systems can be launched from the prompt Mouse Over buttons for a short description Tabs group applications by type/usage Select working directory

4 Getting Started : Where to get help

5 SEGY Seismic Traces 3200 byte reel header 400 byte binary header 240 byte header for each trace Seismic Trace Data : 4 Bytes per sample 3200 byte EBCDIC text header : user defined history 400 byte binary header : sample interval, trace length Trace data in a block First 240 bytes contain header information Four bytes for each digital sample : IBM 32-bit FP

6 Claritas Seismic Format Extended SEGY format, reel header in ASCII Data stored as 4-byte IEEE not IBM FP Fixed trace-header names (CDP, SHOT etc) Index files created for random access and sort Two trace headers identified as primary/secondary keys Reel Header holds the processing history sli name provides key information on a file Use DISCREAD/DISCWRITE READSEGY/WRITESEGY for non-claritas data

7 Basic Components JOBS/JOB1/02_TAR.job Processing Flow steps to be applied in order processed by trace or ensemble parameter form for each module Modify or double click - to access Spreadsheet Files allow parameters vary can vary by header or in time interpolated when used

8 XVIEW : interactive seismic viewer Panel Label Display mode toggle +/- Controls JOBS/JOB1/02_TAR.job Interactive tools Basic processing Panel Controls NMO/Linear velocity

9 Comparing Results JOBS/JOB3/17_shot_compare.job Selects PKEY from Increment 100 More detail in dictionary

10 Comparing Stacks JOBS/JOB3/16_stack_compare.job Fold mode is single MAXFOLD is 1 N_ENS is trace count

11 More Complex Flows JOBS/JOB3/13_DBS_stack.job Reads in a selection of 301 shots Creates 7 repeats Applies deconvolution (repeat key) Sorts the data to CDP order Removes taper on/off NMO and stack Adds an autocorrelation function Displays the data

12 Common Pitfalls NMO, Mute, Geometry doesn t work coord_scale incorrect : -10 for decimetres, 1 for metres REPEAT doesn t work, panels don t work PKEY or last trace flags wrong; DISCREAD, SETLASTR, SETKEY Some modules don t seem to be applied Trace type is not set to 1 for live seismic; check TRTYPE After processing, data is duplicated REPEAT left active after testing, might be in DISCREAD After processing, data is truncated XVIEW used with DISCWRITE (new option in V5) XVIEW repeat displays not quite right Check traces/ensembles count / missing traces

13 Biggest Pitfall SEGY : the non-standard standard! Binary header has incorrect sample rate or number of samples Co-ordinates and co-ordinate scalars don t match correctly Extra or missing headers in file IBM Vs IEEE Vs 4-byte integer for samples ASCII or EBCDIC reel header? Reel header does not have C comment cards Odd headers not set (data start, data end, delay)

14 SEGY_ANALYSER Check and correct headers Read unusual formats XVIEW display for QC trace-by-trace step through can build a READSEGY job can rewrite data (SEGY/Claritas) can identify IBM/IEEE issues can identify endian issues

15 Wavelet : designing filters create filters or wavelets read in seismic (XVIEW) manipulate and compare match data phase conversion filters uses a macro file exercise in tutorial notes

16 AREAL : interactive, spatial QC JOBS/JOB2/GNS_job2.job point and click operation Mouse plus keyboard page up/down, space, R(egain) save flags as edits/ifinfile

17 SV : Seismic Viewer Picking mutes, edits etc. First break analysis (land data) Interactive XVIEW (no job needed) Data controls : Next/previous plus sorting Analysis has same functions as XVIEW zoom Can select toolbars for mutes, AVO etc.

18 CVA : Velocity Analysis Tool Reads stacked and unstacked file Must have CDP numbers in place! Need a guess at velocities to start

19 CVA : setting up the display Configure picking modes centre analysis on nearest V(t) set increment (eg 100 cdps) set T, V windows for CVG/CVS modes define semblance parameters Turn on AGC Usually start in semblance mode pick at a fixed CDP increment easy creation of new functions can fine tune with CVG/CVS Turn on velocity display

20 CVA : Semblance picking Cycle button for picking mode Move, Add, Delete Can also use keyboard M, A, D Press and release to swap mode Press and hold to toggle modes Stack and gather both update Prev/Next to move Main display also updated Activate stack and gather panels

21 CVA : Linked CVG/CVS fine tuning Panels are synchronised on the two displays Keep T window size reasonable Aim is to fine tune in shallow/deep or noisy areas Isovel is automatically updated Effectively layer-strip across dataset

22 CVA : Isovels QC Circulate button controls mode add / delete functions edit or move picks value-replace mode 3D uses XVIEW-style panels Stand-alone version available Stand-along version has: smoothing interval velocity conversion read/write grids and traces gridding options

23 JCS : Job Control System Some tests cannot use REPEAT easily Some tests take a long time to run Create a single master job with named variables included Create a spreadsheet containing the variables to be substituted Select one, some or all of the spreadsheet entries to run Create scripts, run on queues or run interactively Spreadsheet can be updated by the job as they run +

24 JCS : Migration testing JOBS/JOB6/34_JCS_fdmig.job SCALAR would normally be a constant value Now a variable, indicated by angle brackets < > Create a spreadsheet of values to test

25 JCS : In Operation JOBS/JOB6/34_JCS_fdmig.job Scan the job for < > Store these in SEISJOB JCS file named in SEISJOB Tries to match names Asks for links where it can t Select which lines to run Jobs named by SEQnum or NAME