Generalized screen method for prestack time migration

Aiming at the problem trat the conventional wave equation prestack time migration cannot take into account lateral variations of velocity,especially the strong lateral variations.Through borrowing the concept of wave equation prestack depth migration,a wave equation prestack time migration method was proposed,which takes into account the lateral variations of velocity in time domain.A generalized screen wavefield propagator,which recursively propagates along the time direction,was derived in time domain.A prestack time migration algorithm base on the generalized screen wavefield propagator was established by using the time domain one-way wave generalized screen wavefield propagator for propagating the source wavefield and the recorded wavefield along the forward and the reverse time direction,respectively.The tests of the wave equation prestack time migration on the international standard 2D Marmousi model and a real 3D VSP seismic data demonstrated its validity and applicability to the lateral variations of velocity.