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SEG Technical Standards Committee Energistics Western Europe Region & SIG Meeting 17 jun 2008

SEG-D Revision 3.0 Draft. SEG Technical Standards Committee Energistics Western Europe Region & SIG Meeting 17 jun 2008. Why now?. The 2006 2.1 revision was specifically designed as a targeted upgrade to support very high capacity tapes.

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SEG Technical Standards Committee Energistics Western Europe Region & SIG Meeting 17 jun 2008

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  1. SEG-D Revision 3.0 Draft SEG Technical Standards Committee Energistics Western Europe Region & SIG Meeting 17 jun 2008

  2. Why now? The 2006 2.1 revision was specifically designed as a targeted upgrade to support very high capacity tapes. 3.0 was promised in the 2.1 standard to follow soon afterwards and deal with major overhaul and/or upgrades.

  3. Why us? Jill Lewis (Troika International) — Earns living transferring & transcribing data Stewart A. Levin (Halliburton Energy Services) — ProMAX™ SEG-D Input support & upgrades Rune Hagelund (WesternGeco) — Data acquisition and tape management software for WesternGeco field operations Barry D. Barrs (ExxonMobil) — Navigation and positioning expertise

  4. SEG-D issues driving 3.0 • An explosion in data being stored in vendor-specific headers driven by the need for smooth transfer between acquisition & QC/processing • Multicomponent surveys • Higher sampling rates/non-power-of-2 ratios • Beyond 24-bit sensor sensitivity • Continuous passive monitoring • Only non-record format is long byte stream— cumbersome for QC and transcription

  5. SEG-D opportunities driving 3.0 • Nonseismic data? • Positioning standards coordination • Using web documents for dynamic information • Manufacturer list • Media types and parameters • API organization codes • Guidance recommendations and clarifications • Errata and translations • Format validation utilities

  6. Overview of revision 3.0 proposal • All features presented at SEG San Antonio/EAGE London 2007 have been implemented • With a few additions (Source Auxiliary Channel Ref) • SEGD Tape Label, General Header 1 and Demux Trace Header left as is (with a few exceptions) • Be an efficient format for transferring information between acquisition and QC/processing • SEGD is not a processing format • More space for user-defined header blocks

  7. Overview of revision 3.0 proposal • Increased flexibility • Header blocks tagged to allow shot specific (attached to general header) or trace specific information • Block type written in byte 32 of all header blocks • Flexible sample rates, header sizes, reclength etc. • Increased robustness • Tagged header blocks • Size of shot/data in General Header • Simplified encoding/decoding • No complex datatypes, using 4byte float, int etc • Explicit values (ex. #samples/trace)‏ • No dependencies between header blocks • Additional functionality

  8. New features in revision 3.0 proposal • Positions can be tagged to all traces/equipment • Multiple positions (in space and time)‏ • Format TBD by pos group • Support for multi-component data • Node number, trace grouping, orientation header • New General Trailer format • Flexible, allows any data-block to be appended • Standardized edits can be appended to General Trailer • Allows easy addition of edits post-acquisition • 8080: IEEE 8 byte samples

  9. New features in revision 3.0 proposal • All measurements now properly tagged with accurate, absolute timestamp (if available)‏ • Positions, traces, shot, etc. • Allows multiple measurements of same type • All header sizes extended • More room for acquisition system defined blocks • Existing trace ext hdr blocks may be used.... • ...but remember to use correct block tag (byte 32)

  10. New features in revision 3.0 proposal • Support for complex shooting schemes • Multiple source initiations per shot record • Multiple sources firing simultaneously • Support for complex source configurations • Traces and measurements for sources and parts of sources • Align SEG-D with SPS standard and/or SEG-Y revision 1 positioning support

  11. New features in revision 3.0 proposal • Standardizing storage of common survey information • Vessel/crew identification • Survey area name • Client identification • Job identification • Line identification (Record set ID)‏ • Size of record, data, and header explicit in General Header

  12. New features in revision 3.0 proposal • Table Of Contents file • Stored at end (or beginning) of tape • Lists all SEGD records on a tape • Enable fast access to data • May be stored on disk (to simplify data mgt)‏

  13. New features in revision 3.0 proposal • Standardizing storage of SEGD • One header block spanning multiple tape blocks • A trace spanning multiple tape blocks • Fixed/variable block devices • Disk storage • Transfer across network

  14. Thank you for the attention • Questions? • More details regarding the proposal follows this slide

  15. New features in revision 3.0 proposal • Logical numbering of traces/source points extended to handle all operation types • Line number • Point number • Point index • Group index • Depth index • Reshoot index

  16. Sample rate • Sample rate steps of 1 microsecs • No longer a base scan rate • “Dominant sample interval” used for backwards compatibility • Samplerate chosen over frequency • Backwards compatibility • Ability to relate sample to point in time (timestamp)

  17. Timestamp • Counting microsecs since 6 Jan 1980 (GPS epoch)‏ • 8 byte integer • Negative timestamps allowed • 292471 years range • Defined back to 1 jan 1970(SEG-D epoch) • Leap seconds must be added to UTC timestamp(General Header)

  18. New features in revision 3.0 proposal • More sensor types/channel types explicitly supported • Wind, depth, reference signals, source measurements etc. • Sensor sensitivity value stored per channel • Convert to actual physical unit • Support non-voltage measurements

  19. New features in revision 3.0 proposal • Line number -> Record set number • To be usable for all types of operation • Only 3 General Header blocks (#1-3) required in rev 3.0 • Everything else optional • Allows meta-data records (no traces) • Allows zero length traces (only trace header) • Allows trailer only records

  20. Header size extensions • Channel set header block 96 bytes • Header block sizes • General header - 65536 blocks (2 MB)‏ • Channelset header – 65535 blocks (~6MB) • Skew blocks – 65535 blocks (~2MB)‏ • Extended header – 16777215 blocks (~512MB)‏ • External header - 16777215 blocks (~512MB)‏ • Trace Header Extension – 255 blocks (8160 bytes)‏ • General Trailer – 4294967295 blocks (~128GB)‏

  21. Trace size • Traces can be 2147 seconds long • Negative start times allowed • Extended recording mode allows up to 140,735,340 seconds (1628 days) of data to be stored in one record

  22. Filters • Extended filter definitions • Frequencies and slopes are IEEE floats (4 bytes) • Filter type • Filter delay

  23. Positions • Definition not completed yet (work in progress) • “Placeholders” defined • Projection/datum information part of General Header • Only one projection allowed per SEG-D record • Positions part of Trace Header or General Header (sources) • SEG-D position will be binary

  24. Missing from draft • Update Introduction chapter • List of Rev 3.0 changes not complete • 4 figures in chapter 3 not updated (Record format and block layout on tapes) • TOC file Record description requires proper definition • Several lists needs completion (Channel types, Soil types, Sensor types, Physical units, etc.) • Appendix A (Manufacturer list) and C (API Producer code) not updated • Delete Appendix D (Header descriptors)? • Appendix E (Examples) not yet completed • Some questions/topics for discussion listed in red. • All header blocks and Rev 3 concepts completed.

  25. Questions, Concerns and Suggestions? • Volunteers always wanted • We’re taking names • Multicomponent standards • Downhole acquisition support • Metadata additions (temperature, wave height, …) • Opinions too  • We’re taking notes

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