Prestack Time Migration

2D & 3D Kirchhoff prestack time migration

Kirchhoff prestack time migration is a workhorse in land processing, particularly in structural settings. TGS has the ability to run 2D and 3D Kirchhoff prestack time migration (PSTM) with output either to gathers or stack. The KTMIG algorithm honours the true source and receiver topography in its operator construction and the output can be cast onto the original input grid or onto any user specified output grid. The algorithm employs fold compensation techniques to minimize artifacts related to imperfect spatial sampling (similar to the method of Canning and Gardner, Geophysics Volume 63, no. 4, pp 1177-1183, 1998) and has been shown to preserve relative amplitude information. Two QC measures are employed in the migration process: (i) impulse response analysis is routinely performed to assist in aperture control selection, and (ii) migrated output gathers are routinely generated from a constant amplitude synthetic input dataset whose geometry is identical to that of the real survey at hand. Such gathers provide an excellent way to QC the effectiveness of the fold compensation discussed above.

PSTM Poststack



PVEL - PSTM velocity analysis

PVEL is TGS’ interactive program for analyzing and picking migration velocities on panels of data that have been migrated using different trial velocity functions. The program can display migrated gathers as well as stacks. In typical usage, an initial velocity model and percentages of that model are used as input to PVEL. Interpreters are welcome to use this program to pick their own velocities and/or to preview the effect of migrating with any particular trial velocity field.



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