Probing the energy landscapes and adsorption behavior of asphaltene molecules near the silica surface: Insights from molecular simulations

Abstract

Enhanced oil recovery (EOR) is a promising solution to meet the increasing energy demands. However, the efficiency of EOR processes is hindered by the deposition and precipitation of heavy oil components, such as asphaltenes, at various stages of oil extraction. Therefore, a detailed understanding of asphaltene molecules (AMs)–rock interactions is important for designing novel solvents and enhancing the efficiency of existing solvents in oil recovery. Using molecular dynamics simulations, we have investigated the structural and energetic behavior of model AMs in dodecane solvent near the silica surface representing the sandstone reservoirs. We obtained the potential of mean force of AMs (containing three island-type and two archipelago-type AMs), calculated their adsorption–desorption barriers, and compared them among themselves and with solvent molecules. We found a competition between AMs and solvent, where AMs with higher configurational energy than the solvent molecules exhibit preferential surface adsorption. We observed that the heteroatom-surface interactions play a pivotal role in the adsorption of AMs, such that AMs with polar heteroatoms prefer to adsorb onto the surface. Further, the desorption barrier of AMs was found to be proportional to the number of hydrogen bonds formed. We observed that the AMs anchored to the surface through the aliphatic chains lie parallel, whereas those with heteroatom adopt an orientation nearly perpendicular to the surface.