Post-Processing on Common Image Gathers

Oil and natural gas exploration -- geology and geophysics
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jefry123
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Post-Processing on Common Image Gathers

Post by jefry123 »

What post-processing do you suggest for migration output gathers? These gathers are going to be used for AVO analysis.

GuyM
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Re: Post-Processing on Common Image Gathers

Post by GuyM »

What problem are you trying to fix?

There's nothing special about common image gathers forAVo compared to CDP gathers for AVO; you have the same challenges of coherent noise, random noise and and residual non-linearity on the events - which you have to address without impacting on the AVO (or indeed AVA) character.

A lot depends on the quality of the anti-alias operators and imaging; if you have migration artefacts to address then you may find an amplitude-preserving Radon filter may work. Not all Radon processes are amplitude preserving, so check out your specific algorithm (ie is it high resolution? Does it use the Radon-Harlan approach?); as with CDP domain process aliased dipping noise and aliasing in the transform domain are the enemy.

To some extent this will depend on stuff you did before; how much effort you put into addressing aliased noise and removing aliasing, any interpolations and how many offsets/angles you migrated to. If you have spatial undersampling then noise removal will be tricky.

And of course, you may want/need to run a residual NMO/alignment on a given even to ensure it is correctly analysed for AVO effects - the imaging model still going to be imperfect in complex areas.

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