3-D Prestack Migration: Two Implementations
, by John T. Etgen

Two techniques for prestack migration in two dimensions,
the finite-difference reverse-time method and the Kirchhoff integral method,
can be used for prestack migration in three dimensions.
Because of the tremendous amount of data present in
a 3-D survey, the migrations are posed as individual shot profile
migrations.
If the data for one field profile are collected
on an x,y grid (areal data) then the reverse-time
prestack migration is an appropriate method for 3-D prestack migration.
This is most common for high-resolution 3-D land surveys.
If the data for one field profile are collected
only along a line, then the Kirchhoff integral method is appropriate.
Non-uniform spatial sampling is more easily accommodated by
the Kirchhoff integral method.