Common-offset migrations and velocity analysis

Prestack depth migration is very sensitive to velocity errors. This can make it an excellent tooI for velocity analysis. However, to get maximum benefit from this sensitivity to velocity we must choose our algorithm carefully. Most of the sensitivity to velocity arises from the normal moveout (NMO) term, i.e. from the alignment corrections to data recorded at different offsets. It therefore makes sense, in the context of velocity analysis, to design the prestack migration so that the overall procedure does not apply NMO according to a preconceived velocity model.