AN EXPLANATION FOR SOLID-LIQUID-LIQUID-VAPOR PHASE-BEHAVIOR IN RESERVOIR FLUIDS

The appearance of solid-liquid-liquid-vapour phase equilibria in reser voir fluids is explained as an extension of the phase behaviour of bin ary asymmetric fluids. The theoretical approach is demonstrated for th e 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.