Abstract：The paper presented an approach of plane wave decomposition-based wave-equation prestack time migration suitable for the medium of lateralweak velocity variation. By plane wave decomposition of seismic data on CMP gather, we get the gather of common ph plane wave parameter suitable for double square root wavefield extrapolation equation. The ordinary τ-p transform computation is not needed when offset plane wave decomposition on the CMP gather is carried out, the phase-shift method characterized by simple and convenient implement, better amplitude-conserving property and without losing computational efficiency is used for migration of each post-decomposition common ph gather data. After migration, the velocity and AVO lithologic analyses can be carried out on sorted ph ray parameter common image point gather.
