Relative Permeability From Thermodynamics

Abstract

Summary A new theory is reviewed for single-component, two-phase flow in porous media. It integrates thermodynamics with fluid mechanics and includes wettability in the thermodynamic description. It does not make use of the relative permeability concept. Wettability is included through a function that is part of the input to the model, together with an equation of state. A dialogue between this new model and the existing one has been established with the purpose of obtaining some of the input functions of both models. First, we have used information available in the existing model so as to calculate the function necessary for the description of wettability in the new model. The new model then being complete, we use it to find the two central functions necessary to the existing model, the relative permeabilities. We show that these are well defined when flow is characterized as a traveling wave, and we give a formula for their calculation. The formula assumes that a capillary pressure correlation and an equation of state are known, in addition to a constant related to the thickness of the transition region between the two phases.