Page 517 - Acquisition and Processing of Marine Seismic Data

508 11. SEISMIC MIGRATION

FIG. 11.16 The effect of maximum dip restriction on the output of poststack Kirchhoff time migration. For 10- and
20-degree dip limit, steeply dipping events are completely filtered out.

11.3 FINITE-DIFFERENCE to a 35-degree structural dip. Its theoretical
MIGRATION basis consists of the downward continuation of
the recorded wave field, which is equivalent
Finite-difference migration, based on the to the downward movement of the receivers
numerical solution of the scalar wave equation into the subsurface (Claerbout, 1985). A point
by the finite-difference method, either using an source at depth produces signals recorded as
explicit or implicit finite-difference approach, diffraction hyperbolas at the receivers along the
was introduced by Claerbout and Doherty surface. If we move the receivers downwards
(1972). It can handle both vertical and horizontal in finite depth steps, and shorten the spread
velocity variations and produces good results up length during the downward movement, the