Adsorption mechanism of oil components on water-wet mineral surface: A molecular dynamics simulation study

In this article, decane, methyl benzene, pyridine and acetic acid were selected as different polarity components in crude oil, and their adsorption behavior on water-wet silica surface was investigated by molecular dynamics simulation. Simulation results indicated that polar components could penetrate through water film and adsorb on silica surface, while it was difficult for apolar components. And then, the adsorption mechanism of these four oil components was studied, and researched results showed that the adsorption capability of oil components is related to three factors, viz. interaction between oil components and silica surface, penetration in water film and competitive adsorption with water molecules. Furthermore, how the pre-adsorbed polar components affecting the adsorption of apolar components was investigated. The simulation results demonstrated that the pre-adsorbed polar components could improve the adsorption capability of apolar components. Based on our researches, a two-step adsorption process was proposed, viz. the polar oil components preferentially absorbed on mineral surface, and then these polar components, playing the role of anchor, promoted the adsorption of apolar components. Our researches were beneficial to reveal the adsorption process of oil components in the formation of oil reservoir, which was helpful in guiding the oil-displacing agent design and oil exploitation.