A 2-PHASE FINITE-ELEMENT PROGRAM FOR DISPLACEMENT SIMULATION PROCESSES IN POROUS-MEDIA

Program documentation is presented for a two-dimensional, two-phase immiscible flow model. The model is based on the Galerkin procedure and refers to an incompressible system. Capillary pressure and gravity effects are considered. Spatial discretization is obtained by linear-triangular finite elements, by which the terms of elemental matrices are expressed in analytical form, whereas a Crank-Nicolson finite-difference scheme is used for the step-by-step integration in time. A simultaneous-solution technique is used to solve for potentials and saturations. A highly efficient Gauss elimination algorithm is used to solve the set of linear algebraic equations which results from the Galerkin method. The program may be used to simulate displacement processes between two immiscible fluids into porous media, particularly to simulate water injection, for two-dimensional areal and sectional geometries or axis-symmetric geometry. The listing of the computer code written in FORTRAN 77 is included along with a test case to show the use of the program.