Numerical modeling of a compositional flow for chemical EOR and its stability analysis

A new two-dimensional surfactant flooding simulator for a three-component (water, petroleum, chemical), two-phase (aqueous, oleous) system in porous media is developed and analyzed. The compositional physical model is governed by a system of non-linear partial differential equations composed of Darcy's and mass conservation equations. The system is then numerically solved by a finite difference method using the IMPEC (IMplicit Pressure and Explicit Concentration) scheme. Physical properties are described by a set of concentration-dependent algebraic equations. Additionally, a novel numerical stability analysis is presented in order to study the robustness of the new simulator. The oil recovery factor showed a strong dependency on the surfactant properties and phase behavior, which should be carefully evaluated. In order to achieve this, the new simulator utilizes and modifies a simplified ternary diagram to model accurately the component partitioning. Results showed that surfactant partitioning is the most relevant parameter in the recovery process. Numerically speaking, the simulator behaved according to the results obtained in the matrix stability analysis. Using the non-iterative IMPEC, a critical time value was found beyond which the system yielded large oscillatory values for the produced flowrates. The simulator can be employed to design and optimize chemicals used in enhanced oil recovery (EOR) processes before field application.