Multiphase Fluid Flow Through Porous Media

Abstract

As is frequently the case in topics related to fluid mechanics, the field of muItiphase flow in porous media embraces highly diverse phenomena, ranging from the motion of immiscible fluids, through interaction with the medium via the exchange of heat and/or soluble mass and the exchange between phases, to fluid-solid-phase flows accompanied by colmatage (clogging) and suffusion (leaching). The latter area, which includes the whole field of filtration (Davies 1973, Polubarinova-Kochina 1969), is a topic in itself and cannot be considered in the present survey, which is limited to the discussion of immiscible-fluid phases, usually in two-phase flow. Again, while heat or solute may be regarded as an additional phase and may significantly affect mass flow and phase exchange, the transport of these quantities is generally outside the scope of the present discussion. Superficially, flow through porous media appears to offer the possibility of two alternative analytical approaches, based upon either the scale of pore dimensions or the scale of the macroscopic system. The former approach would be expected to lead to detailed boundary-value problems, would incorporate physicochemical properties, and should, in principle, lead to exact solutions from which numerical coefficients can be evaluated. Unfortunately, such a procedure is not fully practicable owing to the geometric complexity of porous media, although valuable qualitative models have been obtained. Usually, authors abandon the capillary scale and take Darcy's law, involving an undetermined constant-the permeability-as the basis of an axiomatic, macroscale approach (Philip 1970, 1973a, 1974). However, in the field of mUltiphase flow many important questions remain unanswered. For example, what factors affect the flow regime and hence the pore distributions of immiscible fluids, with effects of pressure gradient, etc? In immiscible displacement, what proportion is recovered of a fluid initially in the