CO₂ replacement is a promising technology that simultaneously produces methane and carbon dioxide sequestration. In this work, a novel gradual heat injection enhanced replacement method (GHIR) was proposed to improve the methane production from natural gas hydrate sedimentary layer. The effects of heat injection mode on methane recovery, energy efficiency and the optimal operating conditions of GHIR were studied. The results have shown that GHIR enhances the CH4 recovery percentage from 8.0% to 25.4%. EROI could be further enhanced to 20.14. Because the thermal conductivity of hydrate is larger than the dissociation hydrate layer, the heat transfer analysis shown that the incremental heat injection enhanced replacement method (IHIR) is the best mode for gradual heat stimulation combined CO₂ replacement. This work provides a novel method for future marine NGH development and promotes carbon sequestration by applying the CH₄/CO₂ replacement method.

CO ₂置换是一种很有前景的技术，可以同时产生甲烷和二氧化碳的封存。在这项工作中，提出了一种新的渐进式热注入增强置换法（GHIR）来提高天然气水合物沉积层的甲烷产量。研究了热注入模式对甲烷回收率、能源效率和GHIR最佳运行条件的影响。结果表明，GHIR 将 CH4 回收率从 8.0% 提高到 25.4%。EROI 可以进一步提高到 20.14。由于水合物的热导率大于离解水合物层，传热分析表明，增量热注入强化置换法（IHIR）是渐进式热增产联合CO ₂置换的最佳方式。该工作为未来海洋水合物开发提供了一种新方法，并通过应用CH ₄ /CO ₂置换方法促进碳封存。