Abstract：The technique for stratified modeling by phase shift is mainly based on the method of constant-velocity phase shift. It uses proper nonhomogeneous single-way acoustic wave equation and takes each interval velocity as a constant to compute wave field layer by layer. In other words,the lower-layer wave field is taken as source function to compute upper-layer wave field. Thus wave field extrapolation is performed from deep layer to the surface. The technique avoids the error which the method of constant-velocity phase shift may produce because of sharp velocity variation,but inherits its high accuracy;therefore,the technique is very applicable to the case where velocity sharply varies vertically and laterally. Synthetic seismogram proves the technique feasible.
