New insights into methane hydrate dissociation: Utilization of molecular dynamics strategy

Abstract

Abstract Hydrate reserves play a crucial role in energy storage and resources across the world. Gas hydrate formation may lead to various forms of blockages in oil/gas production and transportation processes, resulting in high capital and operating costs. Hence, it is important to determine the methane hydrate formation conditions and to understand the vital process and thermodynamic parameters. In this study, molecular dynamic (MD) simulations are conducted to investigate the microscopic mechanisms/phenomena and intermolecular forces involved in methane hydrate decomposition, where molecular interactions, structures, and behaviours need to be appropriately determined/selected. Through a systematic parametric sensitivity analysis, the impacts of temperature, pressure, and cage occupancy on hydrate dissociation are studied. Furthermore, the diffusion coefficient, density, and heat capacity of the methane hydrates are determined by employing MD strategy. The stability of water cages is examined at various decomposition times, temperatures, and pressures. According to the radial distribution function and mean square displacement of oxygen-oxygen and carbon-carbon atoms, the stability of hydrate cages decreases with increasing temperature, while it increases with increasing the cage occupancy and pressure. The addition of inhibitors (e.g., methanol) to small cavities in the hydrate structure creates new hydrogen bonds between the water and inhibitor molecules in the cages, accelerating the decomposition of hydrates. A good agreement is noticed between the outcomes of this research work and the results obtained in experimental and theoretical studies available in the literature. Analysing the outcome of the present and previous research works, the current study provides new reliable/logical information on the molecular level of the hydrate dissociation process. It is expected that such a research investigation offers effective tips/guidelines to deal with hydrate formation and dissociation in terms of utilization, prevention, and processing.