Abstract：Intermolecular interactions are determined by molecular structural properties, which then determine their solubility properties. Intermolecular interactions, miscibility of model molecules and the resulting colloidal stability of vacuum residue were studied by molecular dynamics simulations. The results show that the more the number of aromatic rings and the shorter the alkyl side chain of the molecular structure, the greater the cohesive energy density and the solubility parameter. In the residue systems, asphaltenes and heavy resins aggregate form a core, and saturated hydrocarbons, aromatic hydrocarbons, and light colloidal molecules form a continuous phase. The molecular structures of resin affect theirs peptization performance. The resin molecules with moderate length side chain have good miscibility with both asphaltene and aromatic hydrocarbon molecules, and have excellent peptization properties. The degree of aggregation of asphaltenes decreases with the increase of concentration of the colloidal molecules. The reason for that asphaltene and saturated hydrocarbon molecules coexist in the same system is the synergistic effect of aromatic hydrocarbons and resin molecules. Therefore, the colloidal stability of the residue depends on the continuity and compatibility of different molecular structures.
