Abstract CH4–CO2 replacement has been considered as a method for methane production from hydrate-bearing sediments to maintain sediment stability. Sediment stability has been studied at both the particle scale and mesoscale. However, the shear stiffness of sediments has not yet been explored. Moreover, the effects of CO2 and CO2–N2 mixtures as injection fluids on sediment stability remain unclear. Thus, this study aimed to determine the variations in shear wave velocity and electrical resistivity during hydrate formation, CH4–CO2 replacement, and hydrate dissociation using two types of injecting fluids (CO2 and CO2–N2 mixture). The results demonstrated that hydrate-bearing sediment could maintain its stability during CH4–CO2 replacement by injecting CO2 or CO2–N2 mixture. Furthermore, injecting CO2–N2 mixture was more efficient for methane production than injecting CO2. The Results also revealed that injecting CO2–N2 mixture could lead to higher stability of sediments during CH4–CO2 replacement than injecting CO2, although the difference in sediment stability was small between the two cases.

中文翻译：

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含水合物沉积物中CH4-CO2置换对横波速度和电阻率的影响

摘要 CH4-CO2 置换被认为是一种从含水合物沉积物中生产甲烷以保持沉积物稳定性的方法。已经在颗粒尺度和中尺度研究了沉积物稳定性。然而，沉积物的剪切刚度尚未被探索。此外，作为注入流体的 CO2 和 CO2-N2 混合物对沉积物稳定性的影响仍不清楚。因此，本研究旨在使用两种注入流体（CO2 和 CO2-N2 混合物）确定水合物形成、CH4-CO2 置换和水合物分解过程中剪切波速度和电阻率的变化。结果表明，通过注入 CO2 或 CO2-N2 混合物，含水合物沉积物可以在 CH4-CO2 置换过程中保持其稳定性。此外，注入 CO2-N2 混合物比注入 CO2 更有效地生产甲烷。结果还表明，在 CH4-CO2 置换过程中，注入 CO2-N2 混合物可以导致比注入 CO2 更高的沉积物稳定性，尽管两种情况下沉积物稳定性的差异很小。