Stress behavior of hydrate-bearing sands with changing temperature and hydrate saturation
Stress behavior of hydrate-bearing sands with changing temperature and hydrate saturation
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含水合物砂土随温度和水合物饱和度变化的应力行为
DOI：
10.1016/j.jngse.2021.104389
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发表时间：
2022
影响因子：
--
通讯作者：
Yongchen Song
中科院分区：
文献类型：
--
作者：
Shi Shen;Yanghui Li;Xiang Sun;Lei Wang;Yongchen Song
自从天然气水合物（NGH）被证实广泛存在于深海地层和多年冻土区以来，水合物研究引起了学者们的极大热情，水合物的商业开发也引起了国际社会的厚望。但从安全开采角度出发，在商业开采前有必要充分了解水合物的力学特性。地质调查显示水合物储层存在明显的温度梯度，且水合物饱和度随储层位置的不同而变化。基于上述背景，本工作对不同温度和水合物饱和度条件下的含水合物样品进行了力学实验。数据表明，样品的强度与水合物饱和度呈正相关，与温度呈负相关。样品的可压缩性受到孔隙中水合物固体的限制。此外，样品的膨胀性与温度呈负相关，与水合物饱和度呈正相关。从实验现象来看，温度和水合物饱和度对样品的力学性能具有耦合作用。随着温度升高和水合物饱和度降低，样品的应力应变行为从软化变为硬化。上述实验结果可归因于温度和水合物饱和度对孔隙空间水合物胶结结构的影响。此外，还建立了应力应变行为与这些影响因素之间的关系。根据上述结果，可以对现有的含水合物样品本构模型进行改进。还可提高水合物储层稳定性分析的准确性，为水合物资源的安全开采提供理论依据。
Since the natural gas hydrate (NGH) was confirmed to be widespread in deep-sea strata and permafrost regions, NGH research arouses great enthusiasm among scholars, and the commercial exploitation of NGH also arouses high expectations of the international community. However, from the perspective of safe exploitation, it is necessary to fully understand the mechanical properties of NGH before commercial exploitation. The geological survey shows an apparent temperature gradient in the hydrate reservoir, and the hydrate saturation varies with the reservoir location. Based on the above background, we conducted mechanical experiments on hydrate-bearing samples under different temperatures and hydrate saturation conditions in this work. The data showed that the samples' strength is positively correlated with hydrate saturation and negatively correlated with temperature. The compressibility of the sample is limited by the hydrate solid in the pores. Furthermore, the samples' dilatancy is negatively correlated with temperature and positively correlated with hydrate saturation. From the perspective of experimental phenomena, temperature and hydrate saturation have a coupling effect on the mechanical properties of the samples. With increasing temperature and decreasing hydrate saturation, the stress-strain behaviors of the samples change from softening to hardening. The above experimental results can be attributed to the effect of temperature and hydrate saturation on hydrate cementation structure in pore space. Moreover, the relationship between the stress-strain behaviors and these influencing factors was established. According to the above results, the existing constitutive model of hydrate-bearing samples can be improved. The accuracy of stability analysis of hydrate reservoirs can also be improved, which provides a theoretical basis for the safe exploitation of hydrate resources.