Abstract：An effective method for solving a partial differential equation of secondary hydocarbon migration is put forward. The effective method involves water drive hydrocarbon migration model,multigrid and LSQR iteration. This method not only greatly speeds up solving a partial differential equation of secondary hydrocarbon migration but also favours solving an ill-posed problem. 2-D hydrocarbon migration model is still taken as an example,but its fast iteration way is also applicable to 3-D problem.Essentially,the method starts from fine grid to iteratively obtain approximate solution,then determines repeatedly the correction and smoothing procedures of sparse grid layer,followed by correctly solving the residual error equation on sparser grid layer. Less computation is needed in its solution,interpolation and restriction procedures. As a rexult,this method can be used to solve some tough 3-D hydocarbon secondary migration problems which could not be solved by modern large computers.
