The Change of Asphaltene Dissolution System was Studied based on Molecular Simulation Technique

Abstract With the increasing scarcity of conventional light crude oil resources in our country, the efficient development of heavy oil resources is of great strategic significance for ensuring national energy security. Asphaltene, as the component with the strongest polarity and the largest molecular weight in heavy crude oil, is prone to association deposition phenomena due to internal component changes and the influence of external temperature and pressure environments, generating various engineering and technical problems. In this paper, the molecular dynamics simulation method is adopted to systematically reveal the interaction between asphaltene model compounds and dispersants, and analyze the interaction energy of the dissolution system. The simulation results show that the molecular weight, the number of conjugated rings, the length and quantity of alkyl side chains in asphaltene molecules all have significant effects on the aggregation behavior of asphaltene molecules. When the polarity of the solvent increases, the solubility of different asphaltenes decreases. In particular, for organic solvents, the interaction energy of perylene model compounds modified by benzene rings is relatively low, and for inorganic solvents, the interaction energy of perylene model compounds modified by heteroatoms is also relatively low. When a dispersant is present in the dissolution system, the solubility will further increase, but the degree of solubilization varies due to the influence of different molecular structures, the amount of dispersant and temperature. Therefore, these asphaltene model compounds can be utilized for simulation analysis to better explore the dissolution law and influencing factors of asphaltenes. It can also provide corresponding simulation methods for exploring the selection of asphaltene dispersants in the laboratory later, and offer guiding directions for the screening of efficient asphaltene dispersants.