Insight into increased stability of methane hydrates at high pressure from phase equilibrium data and molecular structure

The methane hydrate dissociation conditions are measured at high pressures (up to 200 MPa) to fundamentally understand the hydrate properties. The results show an increased enthalpy of dissociation, from about 53 to 58 kJ/mol, as the hydrate equilibrium pressures transition from low (<80 MPa) to higher pressures (up to 200 MPa), indicating greater stability for the hydrates. Molecular simulations are used to understand and explain the increased stability with increasing pressure, by calculating the enthalpy and molecular structure of the phases. (C) 2017 Elsevier B.V. All rights reserved.