An explanation for solid-liquid-liquid-vapour phase behaviour in reservoir fluids

ABSTRACTThe appearance of solid-liquid-liquid-vapour phase equilibria in reservoir fluids is explained as an extension of the phase behaviour of binary asymmetric fluids. The theoretical approach is demonstrated for the model condensate-rich reservoir-fluid ethane (10 mole %) butane (40 mole %) phenanthrene (50 mole %), to which propane is added. Extant solid-liquid-liquid-vapour phase equilibrium data for reservoir fluids, which include asphaltenes, are found to be consistent with the phase behaviour of this model fluid. The implications for the prediction of asphaltene “precipitation” are discussed.