Kinetics of the Formation and Dissociation of Gas Hydrates from CO2-CH4 Mixtures

Sequestration of carbon dioxide (CO 2) in the form of its hydrates in natural methane (CH 4) hydrate reservoirs, via CO 2/CH 4 exchange, is an attractive pathway that also yields valuable CH 4 gas as product. In this paper, we describe a macroscale experiment to form CO 2 and CH 4-CO 2 hydrates, under seafloor-mimic conditions, in a vessel fitted with glass windows that provides visualization of hydrates throughout formation and dissociation processes. Time resolved pressure and temperature data as well as images of hydrates are presented. Quantitative gas conversions with pure CO 2, calculated from gas chromatographic measurements yielded values that range from 23 – 59% that correspond to the extent of formed hydrates. In CH 4-rich CH 4-CO 2 mixed gas systems, CH 4 hydrates were found to form preferentially.