Phase behavior prediction of complex petroleum fluids

The new phase behavior prediction method of petroleum fluids, which was rec ently developed by Manafi et al. for simple petroleum fluids, has been modi fied and extended for application to complex petroleum fluids. A combinatio n of the Peng-Robinson equation of state for phase behavior prediction and the Riazi and Mansoori equation of state for density prediction has been ap plied. The proposed method is applicable for various equations of state as long as they give accurate prediction of phase behavior and densities of hy drocarbons and their mixtures. The composition of petroleum fluids is descr ibed by discrete and plus fraction parts. For the plus-fraction of petroleu m fluids, appropriate distribution functions for molecular mass, true boili ng point and specific gravity are used. The distribution functions required an average value of molecular mass, and specific gravity of the plus-fract ion as input data. Phase behavior calculations are performed for prediction of saturation pressure as well as flash liberation, differential liberatio n and flash-separation, in a wide range of pressures and temperatures for s ix different complex petroleum fluids and compared with experimental data. It is demonstrated that the proposed method can predict the phase behavior of complex petroleum fluids mixtures quite accurately. (C) 2001 Elsevier Sc ience B.V. All rights reserved.