Abstract：3-D modeling is widely applied to the processing and interpretation of 3-D seismic data,and reservoir simulation.The article recommends finite-difference inverse depth migration method,which is simple,practical and suitable to 3-D modeling in inhomogeneous media.The method takes two essential measures: •Improve the forward computation accuracy by making steep-dip approximation of the diffraction term equation. •Ameliorate the adaptability to lateral velocity variation by solving the refraction term equation with the use of finite difference and time shift methods,so that high accurate 3-D simulation result can be derived from any velocity-varied model. Theoretical trial result proves the method feasible.
