Trace Header Update

Users can update the Trace Header on Post Stack (2D & 3D) data during download.

Selecting the Update tick box within the Download Module will result in the Trace Headers, of the Post Stack datasets outputs (SEGY Rev.1), being updated with metadata from the Navigation and CRS defined.

The option of Do not include EBCDIC headers will update the trace headers as below, but will not add the additional EBCDIC headers to the SEGY Rev.1 download. This option will also remove original extended EBCDIC headers from SEGY Rev.1 data stored within the DISKOS Database.

If the Do not include EBCDIC headers option is unselected the output data will include extended EBCDIC headers with available metadata about the CRS used and the dataset information. The end of the Extended EBCDIC Headers will be defined with the following value ((SEG:EndText)).

The following byte locations will be updated:

2D/shot-based:

  • CDPX: 181-184
  • CDPY: 185-188
  • CDP: 193-196
  • Matched SP (i.e. SP in NAV domain): 197-200
  • Scalar applied: 201-202
  • Integer SP: 233-236

3D/line-based:

  • CDPX: 181-184
  • CDPY: 185-188
  • Inline: 189-192
  • XLine: 193-196

The Binary header will also be updated to record the revision level of SEGY and to declare the addition of Extended EBCDIC Headers. The following byte locations will be updated:

  • SEGY (010016 for Rev 1): 3501-3502
  • Extended EBCDIC Header (negative number) 3505-3506