Walkaway VSP Velocity Tomography Modeling and Prestack Depth Migration Imaging of Complex Surface

The foreland basin of piedmont belt is one of the oil prospects and a current hotspot for exploration in western China. Complex surface and structures put forward higher requirements for surface correction and migration imaging. Usually, static correction only solves the vertical component of travel time, and conventional time migration can't accommodate the lateral changes in velocity. Based on the Walkaway VSP data of one well in western China, we studied the Walkaway VSP velocity tomography modeling, wave field continuation and prestack depth migration imaging of complex surface in this paper. The core idea includes updating the velocity model, extending the wave field, realizing the near-surface correction, and completing the f-x prestack depth migration. Know from the test of model data and measured data, the velocity modeling from reflection travel time tomography can provide an accurate velocity model for prestack depth migration, and the one-way wave field continuation and f-x prestack depth migration migration imaging, can effectively solve the wave field correction problem of complex surface. The results show that this method can be applied to prestack depth migration imaging of complex surface and lateral varied velocity medium with universal applicability.