Assessing synergistic effects: Ion-inducing and intermolecular interactions behind the aggregation and migration behaviors of crude molecules

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The aggregation and adsorption of asphalt and resin molecules in the reservoir or pipeline can lead to the blockage of oil extraction channels, which significantly reduces the anticipated oil production. However, the micro-mechanisms behind the aggregating and migrating behaviors of crude molecules still remain poorly understood. In this work, we considered eight types of asphalt and resin molecules as models of crude oil and then built two systems to simulate the aggregation and migration processes, respectively, using molecule dynamics (MD) simulations. In the case of the aggregation process, our findings demonstrated that the aggregation process of crude molecules is directly triggered by metal ions, which are capable of attracting crude molecules containing acidic groups and heteroatoms to form aggregates. And the stacking structures in the forms of face-to-face and edgy-to-face between crude molecules were found to further lead to the formation of larger aggregates. In the case of the migration process, it was discovered that a few ions attached to the reservoir surfaces are able to induce polar molecules or clusters moving toward the surfaces, resulting in the adsorption behaviors of monomers and multimers. Besides, through a sequence of intermolecular interactions, it was found that the pre-aggregated clusters far away from the reservoir surfaces continued to migrate toward the rock surfaces. In conclusion, this work sheds light on the synergistic effects of ion-inducing and intermolecular interactions behind the aggregation and migration behaviors of crude molecules.