Use of Local Grid Reenement and a Galerkin Technique to Study Secondary Migration in Fractured and Faulted Regions

A simulator, which includes a full three dimensional, multi-component and three phase model for secondary oil migration is used to study ow through fractured and faulted regions. A control volume discretization is used to discretize the strongly coupled system of partial diierential equations the model creates. Non-regular and non-matching local grid reenement (LGR) is used in critical areas to ensure the required accuracy. Two solution methods for solving the composite problem LGR create are studied. The simplest one uses the GMRES solver directly on the composite problem. The second method splits the composite problem into one coarse problem and one problem for each reened area. This method is a two level multigrid method which is based on a Galerkin technique. The CPU time and the number of iteration needed for convergence in both methods are presented and compared.