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GLOBE Claritas Seismic data format Link to this post

GLOBE Claritas internal format is an extended form of SEGY revision 0.

The values in the 400-byte binary and 240-byte trace headers are all named, and can be modified using modules like SETHEADER or HDRMATH. All of the 240-byte header has been allocated in this way, and some of the unused areas in the binary header have also been populated.

You can also create additional, named "extended" trace headers if needed, for example as part of a 3D marine geometry sequence. The extended trace headers can also be arrays, and store information like AGC scalars, velocities or model traces.

A full list of the headers names can be found in Appendix A in the manual.

The sample format used is 32-bit IEEE, and the 3200-byte reel header is ASCII, not EBCIDIC.

The format is further extended using a series of "hidden files" that all start with a "." character.
These files contain useful metadata, and care should be taken when moving or copying files to ensure the hidden files are also moved.

These are :

.History : contains the processing history
.Pindex : contains a list of the Primary Keys (the sort-order of the data) for rapid random access
.dth : contains any extended (dynamic) trace headers

Some other hidden files are also used :

.Gindex : created as a map of how to sort the dataset to CDP by the DISCGATH module
.Kindex : created as a map of how to sort the dataset to a specified keys for the DISCSORT module
.Map : created as a map of how to sort the dataset by the SV application

The index and map files allow rapid random access once created.

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