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Forum » Velocities » preparation of velocity data for 3d

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preparation of velocity data for 3d Link to this post

How we create data set for 3d velocity analysis. In job we use setheader module to set cdp= crossline but which key take as primary,
Please explain with example job deck.

Re: preparation of velocity data for 3d Link to this post

If your 3D dataset has been created in Claritas, using for example the BIN3D or the geometry application, there should be no further prep needed for 3D velocity analysis in CVA. All the relevant headers (eg INLINE, CROSSLINE, CDP, INLINE_CDP) should be set and ready for the velocity analysis. Of course, as with 2D CVA, you require a stacked and unstacked version of the dataset. If the dataset was created outside of Claritas we would need to know the current setup of the headers before advising further.

Re: preparation of velocity data for 3d Link to this post


My data set is created in the claritas. for example i have decon gather in shot order then please share the velocity prep job deck.

Re: preparation of velocity data for 3d Link to this post

Velocity analysis for 3D data is very similar to 2D analysis.

You apply CDP geometry to the data (for example by using BIN3D), sort to CDP order and stack. As with 2D you then read in an unstacked (CVA works faster if this is CDP ordered but it doesn't have to be) and stacked version of your data. For 3D the CVA parameter form also gives the option of defining the range of in-lines you wish to work on at a time. 3D velocity analysis requires the INLINE_CDP header to be set on your input stack file.

3D CVA processing requires that the input NMO file is a 3D file
- either a single key pseudo-3D file (where your CDP numbering has been defined to include in-line and cross-line components) with "3D" included in the interpolation qualifier line.
- or a dual key file with primary and secondary keys set to INLINE and CROSSLINE and the process name set to NMO3D.
You can see examples of these formats in the section on NMO in the Claritas help.

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