Effects of particle and pore sizes on the formation behaviors of methane hydrate in porous silica gels

The formation behaviors of methane hydrate in porous media with different particle and pore sizes were studied in a closed system in the temperature range of 267.15-278.15 K. The silica gels were applied as the porous media for the experiments, in which the diameter ranges of the silica gel particles are 0.105-0.150 mm, 0.150-0.200 mm and 0.300-0.450 mm, respectively, and the mean pore diameters are 9.03 nm, 12.95 nm, 17.96 nm and 33.20 nm, respectively. The formation processes of methane hydrate show different behaviors in porous silica gels with different particle sizes. For the particle diameter range of 0.300-0.450 mm, three formation periods were observed for the experiments with the high driving force. For the particle diameter ranges of 0.105-0.150 mm and 0.150-0.200 mm, there is no remarkable discrete formation period, the hydrate durations of different experiments are basically same at the bath temperature above the freezing point and decrease with the increase of the temperature at the bath temperature below the freezing point. The formation rate of methane hydrate increases with the decrease of the particle size and the increase of the pore size. The final gas consumption increases with the increase of the mean pore diameter but is slightly affected by the particle size.