Pore-scale modeling of non-isothermal two phase flow in 2D porous media: Influences of viscosity, capillarity, wettability and heterogeneity

Abstract

This paper addresses simulation of non-isothermal water-oil displacements in porous media at porescale.<br><br>The simulation approach was done by coupling Cahn–Hilliard phase field and heat equations using<br><br>COMSOL Multiphysics™. Finite element method with interfacial adaptive mesh refinement was<br><br>employed to solve the equation system. The approach was first applied to a non-isothermal Poiseuille<br><br>flow through channel, for verification. The model was further developed to study flow instabilities in displacements<br><br>through uniform and dual permeability media. Simulations were performed for the uniform<br><br>medium with different viscosity ratios (M) and capillary numbers (Ca), ranging three orders of magnitude.<br><br>A stability phase diagram for log–logCa–M was constructed and showed a good agreement with<br><br>those obtained by micro-model experiments. Hot water injection in pore scale revealed that active water<br><br>fingers have a major role in propagating heat to the immobile oil. Fluid displacements in a dual-permeability<br><br>medium at different Ca and M showed that lowering M exacerbates the water channeling effect in<br><br>high permeability layer and lowering Ca may result in higher water sweep efficiency due to capillary<br><br>dominant flow. This work demonstrated the feasibility of polymer gel treatment in dual-permeability<br><br>medium to increase the resistant of the high permeability layer, hence divert water to the matrix, e.g.,<br><br>un-swept areas.