Molecular dynamics simulation on the dissociation process of methane hydrates

Abstract

The dissociation process of methane hydrate is simulated at P = 30 bar and T = 315, 320 and 325 K, using NPT molecular dynamics (MD) method. An eight unit-cell methane hydrate is employed as a model system. A series of analytical results concerned with the dissociation process are used to exhibit the continuous changes of methane hydrate from crystal to liquid. As a result, the dissociation of methane hydrate is considered to be comprised of two successive stages. The first stage is the process associated with the diffusive behaviour of host molecules, which gradually leads to the increase of the cell size and ultimately results in the fracture of the lattice structure. Methane molecules will escape from the broken hydrate cavities and aggregate together in the second stage. The fracture of the lattice structure is found to be the key for hydrate dissociation.