1. SEG-D Revision 3.0 Proposal
SEG Technical Standards Committee

2. SEG Field Tape Standards
SEG Field Tape Standards History
1967
SEG-A & SEG-B
SEG-C
1972
SEG-D Rev 0
1979
Rev 1
1994
Rev 2
1996
SEG-D, Rev 2.1
SEG Field Tape Standards
2006

3. Why now?
The 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.

4. 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)
— Umpteen years acquisition software
experience
Barry D. Barrs (ExxonMobil)
— Navigation and positioning expertise

5. SEG-D issues driving 3.0
An explosion in data being stored in vendor-specific headers driven by the need for smooth transfer between acqusition & 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

6. 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

7. Overview of revision 3.0 proposal
All features discussed at SEG New Orleans have been implemented
With a few additions
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

8. Overview of revision 3.0 proposal
Increased flexibility
Header blocks tagged to allow shot specific (attached to general header) or trace specific information
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

9. 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

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
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
8068: IEEE 8 byte samples

13. Sample rate / timestamp
Sample rate steps of 1 microsecs
No longer a base scan rate
Dominant sample interval used for backwards compatibility
Timestamp – counting microsecs since 6 Jan 1980 (GPS epoch)‏
8 byte integer
Negative timestamps allowed
years range

14. New features in revision 3.0 proposal
All measurements now properly tagged with accurate, absolute timestamp (if available)‏
Positions, traces, shot, etc.
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
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

15. 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

16. 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)‏

17. 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 required in rev 3.0
Everything else optional

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

19. 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

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

21. 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