Practical Techniques in Two-Pseudocomponent Black-Oil Simulation

Abstract

Summary An efficient black-oil simulator based on a two-pseudocomponent representation of standard hydrocarbon physical-property data has been developed. This simulator solves the differential equations describing three-phase flow in a porous medium for black-oil, volatile-oil, condensate, and dry-gas systems. The fluid system consists of two-pseudocomponents—separator gas and stock-tank oil—and water. Descriptive equations are obtained by writing molar balances for the water phase, the stock-tank oil component in the hydrocarbon vapor and liquid phases, and an overall balance in the hydrocarbon vapor and liquid phases. The set of equations is solved by use of either a sequential method or a fully implicit method. The mathematical formulation allows rigorous simulation of reservoir problems involving variable bubblepoint or dewpoint pressures. Practical aspects, such as comparing the simulator physical property data to the laboratory PVT tests, performing flash calculations, and calculating phase boundary pressures, are discussed.