Abstract：In wave equation migration,computation method is the key to good data processing effect;and in a given computation rnethod,the very essential point is what difference equation we introduce to replace the partial differential equation.By analysing "WEMIG"program of existing wave equation migrations,we can find that if we take constant weighting coefficients without considering variable geological structures in replacing the partial differential equation by approximate difference equation,we will have an unsatisfactory seismic section that shows some defects such as poorly continuous seismic horizons,blurred fault points,severe arcs,etc.The article describes both derivations and physical meanings of different coefficients.According to seismic wave propagation law,the intertrace variable weighting coefficient W and the variable weighting coefficient θbetween adjacent depth and time are used in difference equation construction,so that different weighting coefficients can be nicely applied to different seismic data,thus improving seismic section.In data processing,small W(1,2,or 3)may be applicable}for the poorly continuous seismic harizons which should be nicely continuous,big W(above 4)for the seismic horizons which show same blurred fault points,and big W and θ(θ≥2) for the part where arcs must be removed desirably.This method can be used desirably in conventional seismic data processing,particularly in detailed processing of seismic data.
