Parallel Simulations of CO2 Sequestration Using a Non-Isothermal Compositional Model
This paper describes an efficient and parallel numerical scheme for multiphase compositional flow. The underlying theory is first presented followed by a brief description of the equation of state (EOS) and the two-phase flash implementation. An iterative “implicit-pressure and explicit-concentrations” (IMPEC) algorithm is then applied to enforce a non-linear volume balance (saturation) constraint. The pressure system is solved using a mixed finite element method, while the concentrations are updated explicitly in a manner that preserves local mass balance of every component. A major application of this scheme is in the modeling of field scale CO2 sequestration, as an enhanced oil recovery (EOR) process or for storage in deep saline aquifers. Thermal energy transfer also plays an important role in such problems since it can effect the phase properties dramatically. Hence, accurate and locally conservative methods are desirable to model the thermal effects. To this end, the paper also presents a time-split scheme for modeling thermal energy transfer which is sequentially coupled to flow. Finally, some numerical results are presented for challenging benchmark problems.