MRI analysis for methane hydrate dissociation by depressurization and the concomitant ice generation

摘要

Hydrate reformation and ice generation may occur under fast depressurizing rate and low production pressure processes caused by lacking sufficient heat transfer in the sediment. This work conducted MRI visualization and analysis for methane hydrate (MH) dissociation by controlling the depressurizing rate gradually to designed production pressures. Obvious hydrate reformation and ice generation can be avoided through this method. MH dissociation behavior was analyzed under different back pressures. Furthermore, ice generation during MH dissociation under rapid depressurization and low back pressure condition was studied. Large amount of ice generated spatially in the vessel. Ambient heat transfer drove ice melt and hydrate dissociation from the surrounding wall in. The saturation of the generated ice in the vessel was also estimated.