Thermodynamics of multiphase fluids in porous media

Abstract

The basic thermodynamics of multiphase fluids in porous media is formulated, starting from equations originally derived by Laplace, Gauss, Young, and Kelvin. Special attention is paid to the conditions of hydrostatic (Laplace) equilibrium and diffusional (Kelvin) equilibrium, and to the stability of the equilibrium states with respect to displacements arising from flow or condensation/evaporation processes. Detailed discussion is given of capillary condensation in both uniform and nonuniform capillaries, for the case of zero and finite contact angles, and for both one and two liquid components. Immiscible displacement is considered briefly.