For sustainable and safe gas production, it is crucial to correctly understand the mechanical properties of clayey silt hydrate reservoirs. To investigate the impact of clay on the decompositional mechanical behavior of clayey silt hydrate sediments during gas production, artificial hydrate samples with illite or montmorillonite were first prepared according to the survey data in the South China Sea. Then, depressurized decomposition was used to simulate the real gas production process. Finally, axial loads at different confining pressures were applied to samples with different residual hydrate saturations in multistage triaxial tests. Results show that clays considerably impact the decompositional mechanical properties of clayey silt hydrate sediments. Although both sediment types exhibit strain hardening and shear shrinkage during gas production, illite-containing clayey silt hydrate samples have a lower stiffness to resist deformation but a higher strength to resist failure than montmorillonite-containing clayey silt hydrate samples at similar residual hydrate saturations. The stress–strain curves of completely decomposed montmorillonite-containing clayey silt hydrate samples almost coincide with those of hydrate-free samples, while those of completely decomposed iIllite-containing samples are slightly higher than those of hydrate-free samples. Furthermore, a modified Mohr–Coulomb strength criterion was established for clayey silt hydrate sediments with different clays during hydrate dissociation. This study guides the future commercial extraction of hydrates from clayey silt reservoirs.

中文翻译：

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粘土对粘土质粉砂水合物沉积物分解力学性质的影响

对于可持续和安全的天然气生产，正确了解粘土粉砂水合物储层的力学特性至关重要。为了研究粘土对粘土质粉砂水合物沉积物在产气过程中分解力学行为的影响，首先根据南海调查数据制备了伊利石或蒙脱石人工水合物样品。然后采用减压分解的方法模拟真实的产气过程。最后，在多级三轴试验中对不同残余水合物饱和度的样品施加不同围压下的轴向载荷。结果表明，粘土显着影响粘土质粉砂水合物沉积物的分解力学性质。尽管两种沉积物类型在天然气生产过程中都表现出应变硬化和剪切收缩，但在相似的残余水合物饱和度下，与含蒙脱石的粘土质粉砂水合物样品相比，含伊利石的粘土质粉砂水合物样品具有较低的抵抗变形刚度，但具有较高的抗破坏强度。完全分解的含蒙脱石粘土质粉砂水合物样品的应力应变曲线与无水合物样品几乎一致，而完全分解的含伊利石样品的应力应变曲线略高于无水合物样品。此外，针对水合物解离过程中具有不同粘土的粘土质粉砂水合物沉积物建立了修正的莫尔-库仑强度准则。这项研究指导了未来从粘土质粉砂储层中商业开采水合物。