Abstract：Solving for formation l.arameter with the use of wave equation inversion is an effective way to perform lithology analysis. However, the solution is difficult because of the ambiguity of wave equation inversion. Hence, optimization method is used in solving to avoid the inversion ambiguity. On the basis of inverse problem of two-dimensional wave equation, we change the mathematic model of the inverse probl, em into velocity calculation, define corresl.onding functional, derive approximate gradient formula for interval velocity calculation, and offer the optimized algorithm for inverse iteration. This algorithm was used to Perform the numerical inversion of complicated theoretical model under different noise levels. Quite good result has been obtained.
