3-D prestack migration of common-azimuth data
####
Biondi, B. and Palacharla, G.

SEG 1994 Expanded abstracts: pp 1175-1178

In principle, downward continuation of 3-D prestack data should be
carried out in a 5-D computational space.
Therefore 3-D prestack migration methods based on the solution
of the one-way wave equation would be computationally inefficient for
most 3-D data geometries and uncompetitive with Kirchhoff methods.
To overcome this limitation, we present a method
for downward continuing common-azimuth data in the frequency-wavenumber
domain in the original 4-D space of the common-azimuth geometry.
The method is based on a stationary-phase approximation of the one-way
wave equation and can be applied to both phase-shift and Stolt migrations.
The proposed migration methods are exact for constant velocity,
and approximate for velocity varying with depth.
However, results of some numerical experiments on synthetic data
show that the approximation is good even in presence of strong
vertical velocity gradients.