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30 November -0001 at 12:00am Last edited: 7 October 2012 6:47pm
We've recently been looking into the EOM module and have discovered some issues - probably explaining why your NMO is not working as expected. This module should be updated in the next release of Claritas. Sorry for any inconvenience.
I don't know a great deal about the equivalent offset migration process, but have been talking to the developer that intially created the module (now retired). Were there any specific questions I could ask him? Since you've skimmed Bancroft's book I assume you know CSPs are common scatter points and have seen the equations defining these - I think Chapter 11.4 is the relevant section. The EOM process will produce 2-sided gathers. This is due to the sign of the offset forming the CSP being defined by the the position of the CSP with respect to the CDP midpoint. Hence bits of a particular trace will be accumulated in several CSPs with differing positive offsets and negative offsets. As well as the Bancroft text you may also find more info at the following website
which contains papers by Bancroft for example -
Equivalent offset migration: the implementation and application update (http://www.crewes.com/ForOurSponsors/ResearchReports/1997/1997-27.pdf)
I hope this post is of some help to you.
24 August 2012 at 11:43am Last edited: 28 August 2012 6:28pm
OK, I have read the Claritas documentation and skimmed Bancrofts book and I don't understand what the EOM module is producing in terms of the CSP gathers. I understand I need to NMO the CSP gathers before stack but on my test data the NMO does nothing and the dipping events on the stack are not migrated. Anyone tried it and have any tips ?
27 August 2012 at 10:16am Last edited: 8 October 2012 7:25am
Thanks. That document link is helpful regarding "what is what" in the CSP gather and in suggesting algorithm improvements to suppress artifacts in the CSP gather. I did something similar i.e. run a simple synthetic from a flat and dipping event in constant velocity and couldn't figure out what was real in the CSP gather or whether it was correct or not. This might explain the comment "a carefully designed front mute may be required". Might the developer have been recommending this mute to remove the artifacts from the CSP gather ?
28 August 2012 at 6:28pm Last edited: 8 October 2012 9:01pm
Glad the provided link was of some help in regards to learning more about the equivalent offset migration method.
I just wanted to reiterate that output from the current EOM module in Claritas is unreliable. However, we have investigated the issues and the module is now in testing with plans to include a fixed EOM module in the next release of Claritas.
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