Methane Hydrates in Spherical Silica Matrix: Optimization of Capillary Water

Abstract

Methane hydrate formation/dissociation behavior in the presence of a fixed amount (10 g) of silica grains with a mean diameter of 30–70 μm has been examined in a non-stirred reactor vessel. We systematically varied the amount of water from 10 to 200 g in steps and probed the methane hydrate formation kinetics and the overall hydrate conversion in a silica–water–methane system. Our results showed that the overall methane conversion monotonically increased from 6.14 to 67.82% by reducing the water content from 20 to 1 g/g of SiO2, while under similar experimental conditions, the hydrate conversion in a pure water system was 4.1%. Interestingly, the time taken for 90% of methane gas consumption in hydrate, in a silica–water–methane system, decreased from 450 to 100 min by reducing the total water content from 20 to 4 g/g of SiO2. Our results also indicated that the methane hydrates in the SiO2 matrix are useful for gas storage upon optimizing capillary water. Moreover, we observed that the water-optimized system shows faster formation kinetics and better hydrate conversion, which are critical for methane storage/transportation.