关键词: 天然气水合物, 降压, 加热, 模型, 数值模拟, 实验验证

Abstract:

The depressurization-induced natural gas hydrate dissociation is limited by heat transfer. This research presented a numerical study of gas production to clarify the dissociation characteristics of depressurization combined with well-wall heating. A 2D cylindrical fully coupled simulator was developed for simulating the laboratory-scale gas production process with depressurization combined with well-wall heating. The simulation results were verified by experimental data. Well-wall heating was beneficial to increasing gas production, and gas generation rate of the depressurization combined with well-wall heating method was higher than the depressurization method alone. Well-wall heating could improve the thermal conditions of hydrate-bearing sediments, but the influence was not large because heat was transmitted to only a small dissociation area due to small heating surface and slow heat conduction. On the other hand, the effect of different heating temperatures on gas production could be neglected. Finally, gas production depended strongly on the boundary thermal conditions. The depressurization combined with well-wall heating method may not be feasible for hydrate exploitation in a surrounding with a lower geo-temperature gradient.

Key words: natural gas hydrate, depressurization, heating, model, numerical simulation, experimental validation