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The Use of Compression Technology to Aid Seismic Interpretation in the Northwest Shelf - Australia Keith Woollard - GeoCom Services Australia Pty Ltd.

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Presentation on theme: "The Use of Compression Technology to Aid Seismic Interpretation in the Northwest Shelf - Australia Keith Woollard - GeoCom Services Australia Pty Ltd."— Presentation transcript:

1 The Use of Compression Technology to Aid Seismic Interpretation in the Northwest Shelf - Australia Keith Woollard - GeoCom Services Australia Pty Ltd

2 Introduction w Technical evaluation of compression from the viewpoint of interpreters and data managers w No performance testing w Pre-beta test software

3 The Need w 3D seismic surveys continue to grow at least as fast as disc capacity increases w Trend toward multi-volume interpretation w Trend to higher resolution w Disc may be cheap, but remains a significant cost Data management Backups/archiving w Performance degradation for large surveys

4 What Is Being Offered w Compression available in next landmark release, version w 3D seismic only w Applications reading 3D seismic in R98 plus will be able to read compressed seismic in Seisworks Syntool Stratworks Poststack Zap

5 Compression w Traditional compression methods LZI, huffman etc. Not suitable for seismic Integerisation is a form of compression using a BFI algorithm Data reduction, resample w Landmarks seismic compression Designed specifically for seismic Not reversible, some loss of data User controls overall distortion level 1 df 99

6 Worldwide Compression Ratios After John Kerr

7 Comparisons Raw 32 bitCompressed (DF=1) 4.6gb501mb

8 Comparisons Notes: 1 Input is 4.6 gb of 32 bit Floating point 2

9 Difference Plots Seismic 8 bit integer 16 bit integer Compressed DF=1

10 Comparisons Raw 32 bitCompressed DF=1 Time Domain Instantaneous Frequency

11 Interpretation

12 Interpretation From Same Seed

13 Logistics w Able to load from seg-y to compressed using bcm3d and PSDL w Able to convert from 3dv to compressed Generally better to reload w Seisworks able to display one volume and track another w Zap able to read compressed directly without need to reduce to 8 bit range

14 Issues w Implications for visualisation and immersion w Electronic data transfer Intra-company Inter-company Quick-look seismic for farm-outs w Data loading means choosing distortion, not scale & clip

15 Issues - Cont. w Compression retains absolute numbers w Compression is too good, prefer DF < 1 w Compression is a route to image individual 3D projects greater than 62 gb w Compression is able to deal with spatially variable amplitudes better than integerisation

16 Performance Issues w Bcm3d to compressed runs 5% slower w Trace ordering of seg-y tapes is significant w Large reduction on network traffic w No testing done on seismic display speeds

17 Recommendations w Always load data compressed rather than integer w Choose DF for standard tracking Survey by survey Company standard GeoCom recommends DF=1 w Additional volume for display / transmitting GeoCom recommends DF=90 w Load ALL volumes (offsets, velocities etc)

18 Summary w Potentially huge savings in disc usage w With DF=1, 16 bit quality in 20% of space w Still a compromise, but a far better one than converting to integer w Peace between interpreters and system administrators (for a while)


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