UNIFIED APPROACH TO THE SOLUTION OF RESERVOIR SIMULATION EQUATIONS.

This paper develops a general method for solving reservoir simulation equations, which is based upon an implicit finite difference formulation of the partial differential equations of compositional thermal simulation, permitting the simulation of nearly all enhanced oil recovery techniques. The general method is used to derive 10 solution schemes, which include the well-known IMPES, Simultaneous Solution (SS), and Sequential Solution (SEQ) methods as sub-cases. The novelty of the general method lies in showing the interrelations of these methods, and also affording the possibility of deriving still other methods. The theoretical development of the general method is given in detail, and the special methods are derived in reference to the reservoir problems for which they were employed.