ABSTRACT
A simulator to model immiscible and miscible displacements was developed. The simulator uses a multi-component, limited-compositional PVT model with pressure dependent K-values. A mixing parameter formulation is included to account for displacement instabilities in miscible studies. The simulator can be used for studies involving a variety of important reservoir fluids. A finite-difference numerical formulation uses each cell's pressure and component masses as primary variables. This choice offers flexibility in coupling PVT models of varying complexity to the reservoir flow equations. The formulation solves the PVT relationships, component mass balances, and a volume constraint simultaneously using a Newton-Raphson method. Of the three nonlinear terms of the component balance equations, the accumulation and well terms are treated implicitly in all variables. In the IMPES method the flux terms are treated implicitly in pressure only. If required, a fully-implicit method evaluates the flux terms implicitly in all variables. The simulator code has been written in an efficient, structured, and modular manner with vectorization of the majority of the cell and matrix calculations. Benchmark problems and examples comparing results from this model to a fully-compositional simulator are presented.
