Interfacial behavior of binary, ternary and quaternary oil/water mixtures described from molecular dynamics simulations

Abstract

The correct description of crude oil/water interfaces is a very complex and an important task, particularly to the oil industry, whosemain difficulty relies on understanding how the interfacial properties (i.e., interfacial tension and interfacial accumulation) of the systemare affected by a very large number of components. To give some additional insight to the oil/water interfacial behavior, eleven oil/water mixtures (i.e., six binary, four ternary and a quaternary mixture) have been modeled through atomistic molecular dynamics simulations at laboratory conditions. All mixtures were built with a model oil based on dodecane, toluene, quinoline and a naphthenic acid, to represent the saturated, aromatic, basic resin and acid resin fractions, respectively. The results from this contribution show that interfacial tensions can be correlated to interfacial accumulation, which can be used as good starting point in predicting interfacial properties of oil mixtures. Additionally, the interfacial properties of mixtures behave similarly to the most polar pure oil/water interface, while all other compounds stay in the oil bulk as spectators. This behavior raises the question of whether using common n-alkane oils is a good enough approximation for modeling the interfacial properties of crude oils.