Molecular dynamics simulation of the interfacial wetting behavior of brine/sandstone with different salinities

At present, the mechanism of the influence of salinity on wettability of reservoir rocks is still insufficient. In this paper, molecular dynamics simulation is used to study the wetting behavior of water droplets on the surface of sandstone under different salinities, and the system equilibrium configuration is used to analyze the interaction among the components of the system. To clarify the mechanism of the influence of ions on the wetting of water droplets on the sandstone surface, the distribution characteristics of anions and cations, ion hydration and the association between anions and cations in the equilibrium system were analyzed. The influence of salinity on the wettability of water droplets on the sandstone surface is comprehensively evaluated by calculating the average interaction potential between ions and water molecules, the change in cohesive energy density among particles in the brine system and the change in the number of hydrogen bonds among water molecules.