Methane hydrate formation/reformation in three experimental modes: A preliminary investigation of blockage prevention during exploitation

Methane hydrate (MH) is a clean energy source with significant potential. However, the hydrate formation/reformation characteristics during the natural gas hydrate (NGH) exploration process must be elucidated. In this study, methane hydrate was formed/reformed in three different modes to simulate the mining of NGH sediment. The experimental results indicated that when the hydrate forms in partly water saturated porous medium in a flow of methane gas, the methane gas flow rate does have a significant effect on hydrate saturation. Hydrate could be formed in larger amounts and faster by the methane displacement of the water-saturated porous medium than in any other experimental mode. However, the pressure curves fluctuated strongly in this mode. When the hydrate was reformed at a constant pressure in partly water-saturated porous medium, the hydrate saturation maxima increased. However, when the hydrate was reformed by flowing methane through the partly water-saturated porous medium, the hydrate saturation maxima decreased. (C) 2015 Elsevier B.V. All rights reserved.