Comparisons of Computational Efficiencies of Different Equations of State and Transport Property Correlations in a Compositional Simulator

Abstract

ABSTRACT Comparison of computational time requirements for four equations of state (Soavé-Redlich-Kwong equation, Peng-Robinson equation, Joffe-Zudkevitch modification of the Redlich-Kwong equation, and the higher-order Conformai Solution Model Benedict-Webb-Rubin-Starling equation) and two viscosity correlation sets (Dean and Stiel for computing gas viscosities; Lohrenz, Bray, and Clark for computing oil viscosities; and the more accurate Modified-Chung-Ajlan-Lee-Starling correlation for both the oil and gas viscosities) for several compositional simulation problems are presented. The results of this study indicate that when the reservoir oil is characterized using 3 components, 10 components, and 15 components, the computational time increases with the number of components. Furthermore, although no specific equation of state was the most efficient in all cases, a particular equation of state may show significant savings for a specific case. The higher-order equation of state requires much greater computational time for the same simulation problems. Comparisons between multicontact miscible and immiscible problems indicate a higher time requirement for the former problem due to time-consuming computations in the critical region. Comparisons between two viscosity correlation sets for several compositional simulation problems indicate negligible differences in computational time, and, hence, the more accurate correlation is recommended for compositional simulators.