Phase behavior of reservoir fluids: Comparisons of PC-SAFT and cubic EOS simulations

Abstract

Cubic Equations of State (EOS) is an industry standard for simulating the phase behavior of reservoir fluids. Especially the Soave–Redlich–Kwong and the Peng–Robinson equations are widely used. Applied with volume correction, these models can generally capture the phase behavior of reservoir fluids in terms of saturation points and gas–liquid ratios. However for gas compressibility factors and oil compressibilities, cubic EOS do not fully meet today's requirements to accuracy. This paper will investigate whether the PC-SAFT EOS can provide an alternative to the cubic EOS that will improve simulation accuracy within the problem areas and still provide the same reliability as the cubic equations with respect to phase equilibrium calculations. The paper will further analyze whether it is a problem for simulating EOR gas injection processes that the PC-SAFT equation unlike a cubic equation is not bound to match the pure component critical point.