Optimizing Carbon Dioxide Injection for Methane Hydrate Development and Carbon Sequestration: A Long-Term Numerical Simulation Study

Although in theory, carbon dioxide replacement for methane hydrate development can simultaneously enhance methane production rates and achieve carbon sequestration, its feasibility under field conditions has not been thoroughly investigated. This study proposes a carbon dioxide injection and methane development replacement strategy using a multiwell injection and production system. A custom-developed hydrate simulator was used to model the replacement process and its long-term evolution over 100,000 years. The results indicate that for shallowly buried hydrate reservoirs in seafloor sediments, carbon dioxide injection can significantly enhance methane production rates. The resulting carbon dioxide hydrates remain stable after the reservoir temperature and pressure recover, which facilitating carbon sequestration. Analysis of reservoir conditions reveals that carbon dioxide replacement is less effective for deeply buried methane hydrate reservoirs. Additionally, shallower water depths and intact seal integrity are favorable for carbon dioxide replacement. To achieve optimal replacement, the carbon dioxide injection rate must be carefully controlled; both excessive injection rates and premature injection can lead to carbon dioxide breakthrough from the injection well to the production well. Overall, this study provides insights into the feasibility analysis, site selection, and operational optimization for carbon dioxide replacement in methane hydrate development and carbon sequestration.