Using GLOBE Claritas 2D/3D Seismic Processing Software June 2008 - PowerPoint PPT Presentation

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

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 www.globeclaritas.com

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 www.globeclaritas.com

Getting Started : Where to get help www.globeclaritas.com

SEGY Seismic Traces 400 240 byte header for each trace byte 3200 byte reel binary header Seismic Trace Data : 4 Bytes per sample header • 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 www.globeclaritas.com

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 www.globeclaritas.com

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

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

Selects PKEY from 100-900 Comparing Results Increment 100 More detail in dictionary JOBS/JOB3/17_shot_compare.job www.globeclaritas.com

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

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 www.globeclaritas.com

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 www.globeclaritas.com

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) www.globeclaritas.com

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 www.globeclaritas.com

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 www.globeclaritas.com

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 www.globeclaritas.com

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. www.globeclaritas.com

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

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 www.globeclaritas.com

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 www.globeclaritas.com

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 www.globeclaritas.com

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 www.globeclaritas.com

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 + www.globeclaritas.com

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 www.globeclaritas.com

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 www.globeclaritas.com