A modified MMM EOS for high-pressure PVT calculations of heavy hydrocarbons

Abstract

A theoretical based cubic equation of state has been proposed (MMM EOS) by Mohsen-Nia (Mohsen-Nia et al., 1995) for calculation of pure fluid and mixture properties Z=(v+1.3191b)/(v−b)−a/[RT^(1.5)(v+b)]. In previous works, the superiority of the MMM has been shown over the vdW family of EOSs for PVT and VLE calculations. In this work, a new simple functional form for its attractive and repulsive parameters [a(T) and b(T)] is introduced. The proposed EOS is applied to vapor pressure and saturated density calculations of different pure fluids. Then, the proposed equation is used to calculate high-pressure PVT of heavy hydrocarbons. The performance of the proposed EOS for VLE calculations is examined against the corresponding experimental measurements for a number of binary mixtures and the results are compared with those obtained from the cubic EOSs frequently used for thermodynamic and fluid phase equilibrium calculations. The comparisons indicate the modified MMM EOS is quite suitable for property predictions of gas and liquid systems, especially for high-pressure PVT of heavy hydrocarbon systems of interest in the oil and gas industries.

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