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Common Offset planes Link to this post

how we sort data in common offset planes. After sorting the data , what is the order of primary key and secondary key.

how we migrate each offset plane separately.

please share examples.


Re: Common Offset planes Link to this post

You can use the DSORT_OFF module to sort data into common offset planes. DSORT_OFF is a specially configured version of the DISCSORT module, and sorts into OFFSET planes with CDP as the secondary key.

Once you have your data sorted in common offset planes, most migration modules should take the data in this order and migrate each offset plane separately.

Just double check the parameters of the migration module you are using. For instance the FDMIG module has a USELASTTR parameter which lets FDMIG process a block of traces when it sees the last trace header flag set (LASTTR=1). You can use this to migrate common offset gathers. The IMAGE_K3T has the STARTOFFSET and ENDOFFSET or OFFSETS parameters which can be used to define the offset range for migration.

Re: Common Offset planes Link to this post

i have used GENSORT module to sort data in offset and cdp order but KPRET2D not wprk with this sort of data. you suggested in your reply use DSOR_OFF module to sort data on offset planes, my question is that is this sort work with KPRET2D module? please explain with example.


Re: Common Offset planes Link to this post

You should be able to sort to offset and CDP order using most of the sort modules, so either DSORT_OFF or GENSORT should be fine. DSORT_OFF is only for offset and CDP order, whereas in GENSORT you can choose your Pkey and Skey.

Unfortunately KPRET2D only accepts data in CDP or SHOT order so you won't be able to migrate by offset plane with that module.

Generally 2D datasets would not be migrated an offset at a time, this is because they are relatively small in terms of input traces so can be well managed on a line by line basis in most computing environments. The common offset approach is only really of benefit when you have large scale (typically Marine 3D datasets) and have access to more than one Cluster. Then running on an offset by offset basis allows you to utilise more resources efficiently to process the data through migration.

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