Effects of Asphaltenes on the Formation and Decomposition of Methane Hydrate: A Molecular Dynamics Study

Oil asphaltene and gas hydrate are two major challenges for the flow assurance in the oil gas industry, but it remains unclear about their interactions because they were often investigated separately. Molecular dynamic (MD) simulations were performed to gain insights into the role of asphaltenes on the hydrate formation in bulk water and at the water gas interface, respectively. The promotion and inhibition effects were elaborated by quantifying the partitioning of water and methane, the distribution of different types of hydrate cages, and the linkage and crystallization of hydrate cages. The influence of asphaltenes on the hydrate decomposition was also investigated, which suggested the theoretical feasibility to employ temperature-programmed heating to initially destroy the hydrate cages at low temperatures and then disassociate the asphaltene aggregates at high temperatures. To our knowledge, this was the first study on the atomic interactions between asphaltenes and gas hydrate, which added knowledge for a realistic understanding of the oil gas flow assurance issues when they coexisted in the multiphase system.