Stability criteria for miscible displacement of fluids from a porous medium

Stability criteria are formulated for displacement of a fluid from an infinite porous medium by a second more dense fluid miscible with the fluid being displaced. Pure displacing fluid is separated from pure displaced fluid by a region of constant thickness in which the two fluids interpenetrate. The steady displacement process takes place at a constant velocity in the direction of gravity. It is shown that appreciable differences in pure‐component densities, viscosity variation within the zone of interpenetration, and the displacement velocity can have a major effect on the stability criteria of such a flow.