Abstract Knowledge of the dynamic responses of hydrate-bearing sediments under small strain conditions is a fundamental issue in terms of evaluating the stability of gas hydrate-bearing layers under natural forces, such as eustatic sea level and earthquakes as well as artificial activities for example gas production from hydrate reservoirs. However, this issue has not yet been fully understood. In this study, a customized hydrate resonance column was utilized to measure the dynamic response of tetrahydrofuran hydrate-bearing sediments with different conditions. The results show that the shear modulus increases exponentially with increases in the confining pressure or decreases in the shear strain, while the damping ratios decrease exponentially under identical conditions. Under the same confining pressure, the shear modulus and damping ratio increases as hydrate saturation rises. The stress sensitivity index (b) of shear modulus decreases monotonically with an increase in hydrate saturation. The shear modulus is negatively correlated with porosity when the tetrahydrofuran (THF) hydrate is predominantly pore-filling type, and the damping ratio and sensitivity index b are positively correlated with porosity. However, when the hydrate is mainly load-bearing type, the shear modulus and damping are both related positively with porosity. This is because the total amount of hydrate in specimens with identical hydrate saturation increases with higher porosity, while the sensitivity index b is negatively related to porosity. The hydrate formed in pores leads to a normal increase in the shear modulus and an abnormal increase in the damping, due to trace amounts of residual water between the surface of the hydrate and the particles. This study provides a basis for the comprehensive understanding of the dynamic responses of hydrate-bearing sediments under small strains. It is of great significance for seismic or sonic well logging evaluations on gas hydrate saturation and its dissociation degree in hydrate reservoirs.

中文翻译：

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小应变下含THF水合物沉积物的动力响应：共振柱试验

摘要 小应变条件下含水合物沉积物的动力响应知识是评估含天然气水合物层在自然力（如海平面和地震）以及人工活动（如天然气）下的稳定性的基本问题。水合物储层的生产。然而，这个问题还没有被完全理解。在本研究中，利用定制的水合物共振柱来测量不同条件下含四氢呋喃水合物沉积物的动态响应。结果表明，剪切模量随着围压的增加或剪切应变的减小呈指数增加，而阻尼比在相同条件下呈指数下降。在同样的围压下，剪切模量和阻尼比随着水合物饱和度的增加而增加。剪切模量的应力敏感性指数（b）随着水合物饱和度的增加而单调降低。当四氢呋喃(THF)水合物以充填型为主时，剪切模量与孔隙度呈负相关，阻尼比和敏感指数b与孔隙度呈正相关。然而，当水合物主要为承重型时，剪切模量和阻尼均与孔隙度呈正相关。这是因为相同水合物饱和度的试样中水合物总量随着孔隙度的增加而增加，而敏感性指数b与孔隙度呈负相关。孔隙中形成的水​​合物导致剪切模量正常增加和阻尼异常增加，由于在水合物表面和颗粒之间残留有痕量的水。该研究为全面了解小应变下含水合物沉积物的动力响应提供了依据。对水合物储层中天然气水合物饱和度及其解离度的地震或声波测井评价具有重要意义。