Modeling pore-scale oil-gas systems using gradient theory with peng-robinson equation of state

Published by Elsevier B.V. This research addresses a sequential convex splitting method for numerical simulation of multi-component two-phase fluids mixture in a single pore at constant temperature, which is modeled by the gradient theory with the Peng-Robinson equation of state (EoS). The gradient theory of thermodynamics and variational calculus are utilized to obtain a system of chemical equilibrium equations which are transformed into a transient system as a numerical strategy on which the numerical scheme is based. The proposed numerical algorithm avoids computing Hessian matrix arising from the second-order derivative of homogeneous contribution of free energy; it is also quite robust. This scheme is proved to be unconditionally component-wise energy stable. The Raviart-Thomas mixed finite element method is applied to spatial discretization.