Molecular simulation study on the stability of methane hydrate confined in slit-shaped pores

The stability of natural gas hydrates in confined space is highly related to several scientific and technical problems, such as the estimation of amounts of hydrates in reservoirs and its stability, the usage of hydrates as media for storing and transporting gases, and the sequestration of carbon dioxide in the form of hydrate. By performing massive molecular simulations, we established phase boundaries of methane hydrate in confined space and evaluated the effects of pore size and pore surface properties on the stability, growth, and decomposition of gas hydrates. The results indicate that the melting points of methane hydrate are controlled by the slit size, while the mineral surface has a minor effect on it. In addition, the specific surface area of the hydrate particles determines the stability of the hydrate in silica slits. Our further analysis reveals that methane hydrate has faster dissociation kinetics in confined space than that in bulk phase, and methane hydrate dissociates faster in the hydrophilic system than in the hydrophobic system. The implications of our results with a schematic model on the formation and dissociation of gas hydrates in sediment conditions and porous materials are discussed. (C) 2022 Elsevier Ltd. All rights reserved.