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Book Chapter

Model 4: T-V Picks QC, NMO, Stack

January 01, 2005


Now that we have a file of time-velocity (t-v) picks at selected CMPs, we check the quality of those picks. Then, we apply NMO to the data. After reviewing the results of NMO, it is simple (a one-line command) to stack the gathers.

For the sake of presentation in Section 8.2.1, what was one line in vpick4.txt (line 1) are now two lines in (lines 13-14). Notice that THERE ARE NO SPACES AT THE END OF LINE 13 AND NO SPACES AT THE BEGINNING OF LINE 14.

We removed line 2 from file vpick4.txt. That line would be between lines 14 and 15 below. We removed it because A COMMENT LINE WITHIN THE LINES OF AN SU COMMAND WILL MAKE THE SCRIPT CRASH.

We also removed the continuation mark from the end of line 50.

At the end of interactive velocity analysis (Section, we have a file that contains a row of cdp values. Also within that file, there is a pair of tnmo values and vnmo values for each cdp value. Before we use these cdp-tnmo-vnmo values in normal moveout correction (NMO), we want to check the quality of our picks.

Each time series (set of tnmo values) input to the Seismic Un*x NMO program, sunmo, must increase in time. In other words, in a time series, each successive pick must be at a later time than the previous pick. The following script,, offers a fast way to check that the tnmo values are acceptable to

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Society of Exploration Geophysicists Course Notes

Seismic Data Processing with Seismic Un*x: A 2D Seismic Data Processing Primer

David Forel
David Forel
Michigan Technological University
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Thomas Benz
Thomas Benz
Michigan Technological University
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Wayne D. Pennington
Wayne D. Pennington
Michigan Technological University
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Society of Exploration Geophysicists
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Publication date:
January 01, 2005




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