Front-Tracking of Three-Dimensional Piston-Like Displacements in Porous Media

Abstract

ABSTRACT In this study, a front-tracking method for three-dimensional piston-like displacement is described. Many reservoir processes develop distinct fronts (discontinuities) that move through the reservoir. When the width of the discontinuity is smaller than realistic computation mesh sizes, standard methods are not always adequate. By tracking frontal movement, accurate representation of the front location is provided. This is accomplished by approximating the flow domain as regions of homogeneous properties separated by sharp, distinct fronts. Flow is treated as a succession of steady-states based on incompressible fluids. With these assumptions, the potential equation is solved by finite-element methods, and the front moved accordingly. Elements are originally aligned with streamlines based on single-phase flow so that mesh orientation effects are minimized. As the front moves, elements are reformed to represent the discontinuity at the front accurately. The validity of the model is tested against data available in the literature. The model provides an inexpensive and accurate solution for problems such as coning, gravity under- and over-ride, fluid displacements, and movement of chemical reaction or gas condensation fronts, in which movement of the front is of primary concern. The method is applicable to two fluids of any mobility and density contrasts.