In reservoir simulation, the grid size is usually too large, to give accurate results, especially in active regions near wells and displacement fronts. A grid refinement of the whole domain is very memory and CPU time consuming for field-scale simulations. Dynamic local grid refinement can be used to overcome this problem.

In this paper, an adaptive local grid refinement method is presented for two-phase threedimensional immiscible flow. Data structure and grid management are proposed which are very efficient for dynamic grid monitoring. Several levels of refinement are allowed, space discretization is based on the finite-volume method. The linear system is solved by an ILU-ORTHOMIN method well-suited for irregular gridding. The criteria for refinement and unrefinement are based both on the saturation threshold and the flux tolerance.

Some examples are given to show the ability of the adaptive method to track the displacement fronts in heterogeneous reservoir simulations. The quality and accuracy of the solution are similar to those obtained with a fine discretization over the whole domain while great savings of grid blocks and computer time are obtained.

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