Modeling of multi-component multi-phase porous systems is fundamental to the study of geological processes. Recipes of continuum mechanics and thermodynamics are employed here in order to derive a closed system of equations. We start from a set of balance equations for mass, momentum, energy, and entropy written for a general multi-phase multi-component system. Based on a local thermodynamic equilibrium assumption and non-negativity of entropy production, we choose thermodynamically admissible expressions for fluxes and sources in the set of balance equations and present a closed system of equations.