Production Characteristics of Water-Saturated Methane Hydrates under Different Thermodynamic Conditions

Methane hydrates are seen as a promising clean energy source for the future in response to the energy crisis and environmental protection. In order to investigate the production characteristics of methane hydrates, numerous studies have been carried out under different conditions, but few were conducted in water-saturated sediments, which much resemble the real marine hydrate environment. In this study, seven experimental cases of water-saturated methane hydrates were employed to investigate their dissociation and gas production characteristics by depressurization under different thermodynamic conditions. Both the dissociation backpressure and temperature can promote the hydrate dissociation process by increasing the strength of heat and mass transfer. During the hydrate dissociation process, the sediment temperature of the water-saturated sediments was found to decrease with depressurization, and most hydrates were dissociated in the constant pressure stage with a low sediment temperature of good heat transfer. It is also found that the kinetics of hydrate dissociation in the depressurization and constant pressure stages depend on depressurization rate and heat transfer ability, respectively. This study results in a deeper understanding of marine hydrate production.