A new numerical simulator was developed from the widely used CH₄ hydrate simulator TOUGH + HYDRATE to realize the simulation of hydrate exploitation by CO₂/N₂–CH₄ replacement. Focusing on actual hydrate reservoir, CO₂/N₂ injection combined with depressurization in a practical continuous injection-production mode was applied for gas production. The influence of feed gas composition and injection pressure on CO₂ sequestration and CH₄ production was investigated. Moreover, we conducted a fair comparison and revealed the advantages of CO₂/N₂ injection over two traditional methods in gas/water production performance. During gas injection, a continuous CO₂/N₂ separation process under stratum environment was observed, and the whole gas replacement process can be roughly summarized as a continuous cycle of CH₄ hydrate dissociation and CO₂/N₂ hydrate formation. Increasing N₂ mole fraction from 30% to 50% significantly enhanced the CH₄ production efficiency, while its increase from 50% to 100% mainly resulted in more N₂ production and higher injection-production ratio. Raising the injection pressure from 4.5 to 5 MPa improved CH₄ recovery by 1.5 times, while increase from 5 to 7 MPa reduced CH₄ recovery by 8.3%. A favorable CH₄ recovery with relatively low cost can be achieved by finding an appropriate balance between CH₄ release and CO₂ sequestration.

从广泛使用的CH ₄水合物模拟器TOUGH + HYDRATE开发了一种新的数值模拟器，以实现通过CO ₂ / N ₂ -CH ₄替代水合物开采的模拟。针对实际的水合物储层，将CO ₂ / N ₂注入与减压相结合，以实际的连续注入生产方式进行天然气生产。研究了进料气组成和注入压力对CO ₂固存和CH ₄产生的影响。此外，我们进行了公平的比较，并揭示了CO ₂ / N ₂的优势两种传统方法注入天然气/水的生产性能。在注气过程中，在地层环境下观察到了连续的CO ₂ / N ₂分离过程，整个气体置换过程可以概括为CH ₄水合物离解和CO ₂ / N ₂水合物形成的连续循环。将N ₂摩尔分数从30％增加到50％可以显着提高CH _4的生产效率，而将其从50％增加到100％则主要是导致N _2的产生更多和注入生产率更高。将注射压力从4.5 MPa提高到5 MPa可改善CH ₄回收率提高了1.5倍，而从5 MPa提高到7 MPa降低了CH ₄回收率8.3％。通过在CH ₄释放和CO ₂隔离之间找到适当的平衡，可以实现成本相对较低的有利的CH ₄回收。