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In principle, we don't need to migrate the data with the correct velocity
for the primaries, just a velocity that satisfies the inequality
. This will guarantee
that the multiples are overmigrated and the primaries undermigrated. Since
we are more willing to tolerate some leftover multiple energy rather
than to lose primary energy, the second part of the inequality is more
critical. Unless
there are very strong lateral velocity variations, a simple *V*(*z*) will
probably suffice since both migration and adjoint-migration are performed
with the same velocity model. Migrating with a *V*(*z*) model has the obvious
advantage that the migration and adjoint-migration will run faster.

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Stanford Exploration Project

4/5/2006