Abstract：3-D pre-stack depth migration is a ideal technique for solving the seismic data imaging problem in condition of complex subsurface structure and high lateral varying velocity.The key of the technique is correctly building velocity model in depth domain and objective judgingly migration imaging effect.Using 3-D pre-stack depth migration processing software-GeoDepth,the paper conducts 3-D pre-stack depth migration processing for seismic data in Qianmiqiao buried hill of Dagang Oilfield and adopted a good processing results. The processing method can be summed up as follows;① picking up velocity layer in time migrated section and building up geol匆cal model in time domain;② evaluating interval velocity layer by layer and building up interval velocity model in depth domain combining coherent inversion with verity transformation;③ interactively modifying and optimizing the velocity model in depth domain using residual velocity analysis and tomographic imaging;④realizing 3-D prestack depth migration by selecting Kirchhoff integrating summation.
