Molecular dynamics simulations to evaluate the decomposition properties of methane hydrate under different thermodynamic conditions

Understanding the thermodynamic effect on methane hydrate decomposition is beneficial for designing controllable methane recovery processes under conditions of continental margins and oceanic sediments. In this work, we systematically examined the effects of varying temperatures and pressures on the natural gas hydrate decomposition in the presence of 20 mol% methanol through the molecular dynamics approach. Taking advantages of key parameters of angular order parameter (AOP), radial distribution function (RDF), mean square displacement (MSD), and potential energy, we mainly aimed to explore the impact of temperature and pressure on the decomposition of methane hydrate. It can be founded that high temperature is a positive factor for the methane hydrate decomposition, and as the temperature increases from 272.15 K to 277.15 K, the promotion effect becomes more obvious, resulting in a reduction of decomposition time by 3.93 ns. On the contrary, pressure has a negative effect on the methane hydrate decomposition, and as the pressure increases from 1 bar to 200 bar, the inhibitory effect becomes smaller. Additionally, the potential energy as a function of time can be used to evaluate the decomposition rates under different thermodynamic conditions. The obtained results underscore the significant dependence of methane hydrate decomposition rates on temperature and pressure, providing essential guidelines for optimizing gas hydrate decomposition processes.