The replacement of methane molecules with a theoretical equal number of CO₂ molecules, is one of the most promising opportunities for the exploitation of natural gas hydrate reservoirs. In this work, the effect of depressurization on CH₄ hydrates was analysed in depth. Different pressure drops, from 5 to 15 bar were tested and described in terms of free gas removed (desired event) and hydrates destroyed (undesired event) before the injection of carbon dioxide. A few pronounced pressure drop might be not enough to ensure an effective replacement, while an excessive one might be not sustainable due to the high quantity of hydrates destroyed before the process. In this work, variation of hydrates and free gas was evaluated before and after depressurization; it was then compared and employed to define an optimum range of pressure drop to optimize the process. It was proved that the quantity of hydrates destroyed increases with the pressure drop imposed, while the removal of free gas shows a maximum. When depressurization was close to 10 bar, only 18.57% of hydrates dissociated, while the quantity of free gas removed was three times higher (59.27%). Finally, the CO₂/CH₄ replacement process was carried out with the optimal depressurization degree previously defined.

_{用理论上相等数量的CO 2}分子代替甲烷分子是开发天然气水合物储层的最有希望的机会之一。在这项工作中，减压对 CH _4的影响水合物进行了深入分析。测试并描述了从 5 巴到 15 巴的不同压降，并描述了在注入二氧化碳之前去除的游离气体（期望事件）和破坏的水合物（不期望事件）。一些明显的压降可能不足以确保有效更换，而过度的压降可能是不可持续的，因为在此过程之前会破坏大量的水合物。在这项工作中，评估了减压前后水合物和游离气的变化；然后将其进行比较并用于定义最佳压降范围以优化工艺。结果表明，随着压降的增加，水合物的破​​坏量增加，而游离气体的去除量最大。当减压接近 10 bar 时，只有 18.57% 的水合物解离，而去除的游离气体量则高出三倍（59.27%）。最后，CO₂ /CH ₄置换过程是在先前定义的最佳减压度下进行的。