Unveiling the molecular interactions of surface wetting modification in porous medium: A groundbreaking insight into wettability alteration

Recently, discussions have been raised surrounding the cause of changing wettability during brine salinity engineering. The goal of this study is to decode the reason behind wettability changes by introducing a novel approach involves both monovalent (Na+) and divalent (Ca2+) ions. Through molecular dynamics simulations, the study investigates the underlying physiochemical interactions responsible for wettability modification via configuring the amorphous cells and integrated layers. Various metrics were analyzed including the radial distribution function, diffusion coefficient, adsorption energy, mixing energy, solubility parameter, and molecular configurational changes. The results demonstrate the significant influence of oil polarity and the role of sodium ions with a maximum diffusivity of 1.2 � 10�4 cm2/s. Calculations reveal that sodium chloride ions are two orders of magnitude more active than calcium chloride ions. The most notable finding of this study involves the identification of two new mechanisms termed the �brine Prong� and �oil Vortex� effects that play a crucial role in separating oil from the surface and inducing changes in the wetting state. Overall, the results offer significant insights into the fields of engineering water flooding and the interaction between brine, oil, and rock to elucidate the wettability alteration phenomenon in porous medium and secure enhancement of oil production. © 2023 Institution of Chemical Engineers