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Forum » Velocities » Semblence

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Author Topic: Semblence 784 Views

Semblence Link to this post

I have a problem with the semblence window. It ignores all the gathers and only end up with one gather trace. I have attached some image so you could see the problem.

Re: Semblence Link to this post

Unfortunately, the images didn't seem to be attached?
If you could give us some more detail, take a step by step through what you are doing, and what you are trying to achieve.
In the CVA application the semblance analysis window option displays the velocity semblance spectra at any CDP, or supergather. The semblance can either be calculated along constant velocity trajectories between a set range, or along a fan of velocities which are percentage multiples of the current velocity function.

Re: Semblence Link to this post

I want to do a velocity analysis and I want to look at the semblance while picking the velocities to ensure that my picks are realistic. However, the semblance does not seem to be correct and there is only one trace in gathers window for each CMP.

I have attached the images again.

Attached Files

Re: Semblence Link to this post

How is the data stacked? From the images it looks like there could be a problem with the stack - when selecting the location for the semblence analysis CVA is finding more traces than expected. If you send us an email to claritas.support@gns.cri.nz we can let you know how you can send us your CVA input data so we can try to repluicate the issue here and take a look at what might be going on. Emailed screenshots of your parameters in the CVA 'CVA application parameters', 'Params' - 'Analysis calculation parameters', and 'Params' - 'Analysis location parameters' forms could also be helpful for sheding light on the issue.

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