Page 524 - Acquisition and Processing of Marine Seismic Data
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11.4 FREQUENCY-WAVENUMBER (f-k) MIGRATION 515
The amount of stretch depends on the ratio outputs indicate undermigration for 0 < W < 1,
between the V RMS of the time sample and the and overmigration for 1 > W > 2. For most
smallest RMS velocity of the whole dataset. For marine seismic data, W ¼ 0.5 or 0.6 generally
constant velocity media, W equals 1.0, and if produces acceptable results for recent sediments.
the velocity varies with depth, W ¼ 1 is not a
valid value any more. In general, W < 1 implies 11.4.2 Effect of Velocity on f-k Migration
undermigration while W > 1 indicates overmi-
gration. The f-k migration results for different Both Stolt and Gazdag migrations are sensi-
Stolt stretch factor values are shown in tive to migration velocity errors, like Kirchhoff
Fig. 11.24 for real marine seismic data. Migration migration, and both display similar responses.
FIG. 11.24 Effect of Stolt stretch factor on the output of Stolt migration.
