Subsurface Carbon Dioxide Sequestration and Storage in Methane Hydrate Reservoirs Combined with Clean Methane Energy Recovery

CO2 sequestration and storage into methane (CH4) hydrate sediments are investigated in this study to evaluate CH4 replacement by CO2 in hydrates through both the macroscale and microscale experiments under varying thermodynamic conditions. The kinetics of CO2-CH4 replacement in hydrates was experimentally evaluated using the production/CO2 sequestration setup within the methane hydrate stability zone (HSZ) and within (HSZ-I)/outside the CO2 HSZ (HSZ-II). These results were further extended at the microscale using a visual glass micromodel to validate the CH4-replacement/CO2 storage kinetics in the presence of a commercial kinetic hydrate inhibitor (KHI) to explore the feasibility of the KHI for mitigation of CO2 hydrate blockage during CO2 injection. Up to 71% CH4 gas recovery was obtained in the macroscale excess gas experiments within the HSZ-II, whereas the higher water saturation condition diminished this CH4 recovery by 9.3%. Deep inside the HSZ-I, a significant CH4 production of 51.7% was obtained (in frozen conditions) with the 1% inhibitor application in water. For the first time ever, our novel microscale micromodel evaluations clearly revealed the release of CH4 gas through the convection, slow CO2 diffusive mass transfer, and the CO2-CH4 replacement, within the HSZ-I. Moreover, this process potentially benefits from the long-term permanent CO2 sequestration and storage in the form of clathrate hydrates while offsetting the cost of its injection through the clean energy methane recovery.

Automated summary

This study investigates CO2 sequestration and storage into methane (CH4) hydrate sediments, examining the replacement of CH4 by CO2 in hydrates under varying thermodynamic conditions at both the macroscale and microscale levels. The results show high CH4 gas recovery within HSZ-II, while higher water saturation conditions diminish this recovery. In addition, significant CH4 production is obtained deep inside HSZ-I with the application of inhibitors. Our novel microscale micromodel evaluations reveal the release of CH4 gas through convection, slow CO2 diffusive mass transfer, and CO2-CH4 replacement within HSZ-I.