A Comparison of Three Equation of State Compositional Simulators




Thele, Kent Joseph

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During the past two decades, approximately one formulation per year has been published for compositional simulators. However, until now, no consistent comparison has been made on any of them. Three of these formulations were implemented on the Dual Cyber 170/750 machine and compared. Formulations by Nghiem, Fong, and Aziz (NFA) and Young and Stephenson (YS) were programmed for one and two dimensional problems, and the fully implicit formulation by Coats (C) was coded for one dimensional applications. These formulations were compared with respect to computer memory requirements, accuracy, and number of iterations and computation times required to satisfy carefully chosen convergence criteria. The phase behavior was modeled with the Peng-Robinson equation of state, and the flash calculations were performed using an accelerated successive substitution scheme by Mehra, Heidemann, and Aziz. From three to fifteen components were used in the test problems which consisted of multiple contact miscible and immiscible gas drives, a minimum miscibility pressure determination, and a carbon dioxide flood in a half of a five-spot pattern.


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