EnCana Workstation SEGY Standard
This document explains why we developed a new Workstation standard by taking the best of the former AEC (Alberta Energy Company) and PCP (Pan Canadian Petroleum). The external naming standard closely follows the former PCP convention and the internal definition the former AEC standard. To ensure that these standards have been adhered to, a check program is provided so all data can be checked before it is delivered.
The Why for the EnCana Workstation SEGY standard
- Besides facilitating data exchange, the workstation format provides double duty as the internal file format for both SeisX and SeisWare. Whether you like it or not, the Workstation SEGY already is a standard, it is estimated that millions of segy files exist in this format.
- Data can automatically be checked, validated and archived on our Static SEGY data servers.
- Unique reference number (like a bar code) exists in two places, as part of the external name and the internal binary header. This provides a simple line verification check
- The Original Line Name exists in two places, as part of the external name and as an ASCII name inside the binary header. This is the name used by SeisWare and SeisX for the base map.
- This Workstation format will facilitate the exchange of gather data between different companies. (floating datum at trace is the key field)
How to display Trace Header values
 Shot points (orange), fold, Total Statics (yellow), Elevation (blue) |
The seismic line to the right to the right shows what these horizons can look like.
Click on the image to see more detail. If you are curious how I generated the velocity file underlay, click here.
Here's how to do it. First step is to make of a list of the files you want to extract the trace header information from and
then run the head2hor.pl script.:
ls *sgy > junk ~ekeyser/perl/head2hor.pl Datum = 1100 Replacement_Velocity = 3300 ns=1501 geometry=2 format=1 name=A22324 A22324 470.250 569661.0 6190924.0 1 768 -1 171 A22324 470.500 569690.0 6190938.0 2 771 -1 170 A22324 470.750 569720.0 6190952.0 1 774 -1 171 A22324 471.000 569750.0 6190966.0 2 777 18 172 A22324 471.250 569780.0 6190981.0 3 778 -1 169 A22324 471.500 569810.0 6190995.0 4 780 -1 166 A22324 471.750 569841.0 6191010.0 4 781 -1 166 A22324 472.000 569871.0 6191024.0 4 782 18 166 A22324 472.250 569900.0 6191039.0 5 786 -1 164 fini --From this example the program is able to use the datum and replacement velocity to place the elevation at the correct time, there are 1501 time samples, the data are 2D and the data are IEEE float.
Here is what the output looks like:
head -10 elevations.exp 4 -9999.99 ELEV C Blue STATIC C Gold FOLD C Peru SP_loc C Salmon A22324 470.250 569661.0 6190924.0 201 171 1 -1 A22324 470.500 569690.0 6190938.0 199 170 2 -1 A22324 470.750 569720.0 6190952.0 197 171 1 -1 A22324 471.000 569750.0 6190966.0 195 172 2 18 A22324 471.250 569780.0 6190981.0 195 169 3 -1Simple, eh?
Why can't I use the SEGY Rev1 standard?
- Floating point numbers are not allowed in the binary and trace headers
- The proposed IEEE Format code of 5 is already being used by SeisX and SeisWare to signify 8 bit data and by Gulf to signify 36 bit data on a UNIVAC computer!
- Extended Textural Header record definition is used by the SeisX line name
- A few missing fields
- Datum and replacement velocity in the binary header
- Line name and reference number ASCII fields in the binary header
- ... see more reasons here
- Not enough information for gathers (or pre stack) data to be exchanged (floating datum at trace missing)
- It's an exchange format only, the format is not used by existing workstation vendors.
- It's been out for several years and I can't find anyone using it!
Why can't I use the CSEG SEGY standard?
The CSEGY standard is pretty good as an data exchange standard. It did declare the number 6 as the first unused number Sorry boys but 5 had already been taken. Good, but not good enough to be used as a workstation standard because:- Floating point numbers are not allowed in the binary and trace headers
- The Datum and Replacment velocity are not hard coded into the binary header.
- Not enough information for gathers (or pre stack) data to be exchanged
- Format is not used as the internal format by existing workstation vendors.