SOLUTION OF TWO-PHASE FLOW PROBLEMS USING IMPLICIT DIFFERENCE EQUATIONS

Abstract

Many difference equations used to approximate reservoir flow problems treat the phase pressures implicitly but not the mobility- density coefficients. Such difference equations are neither wholly explicit nor implicit, but might be described as mixed. This paper outlines the development of a completely implicit difference analog for reservoir simulation, along with a Newtonian iterative method for solving the resulting nonlinear set of algebraic equations that arise at each time step.