天然气水合物岩样三轴力学试验研究

Triaxial Compression Test on Synthetic Core Sample with Simulated Hydrate-Bearing Sediments

天然气水合物是一种洁净、高效、资源量巨大的新型能源,而天然气水合物的力学性质与水合物的钻探、海底地质灾害等密切相关,因此,开发天然气水合物需要了解其力学性质。为此,用覆膜砂烧结成岩样,采用原位合成方式制取不同水合物饱和度的水合物沉积物岩样,利用自主研制的水合物原位测量系统,在不同围压条件下研究了不同水合物饱和度的水合物沉积物岩样的力学性质。结果表明,水合物沉积物岩样的抗压峰值强度随着围压、水合物饱和度的增大而增大,内聚力随着水合物饱和度的增大而增大,而泊松比、内摩擦角不随水合物饱和度变化。根据库伦-摩尔准则并结合试验结果建立了围压、水合物饱和度与含水合物岩样峰值强度的半经验数学模型,可为深水水合物钻探所涉及的水合物强度参数的选取,以及室内试验的理论分析及数值模拟提供一定的支持。

Natural gas hydrate is a new energy of clean, efficient and large amount of resources. The researches on mechanical properties of hydrate-bearing sediments is closely connected with hydrate drilling, geological hazards and many other aspects. Therefore, the developments of gas hydrate need to know the mechanical properties of the gas hydrate. For this reasons, coated sand in the laboratory was sintered into the test specimen,and then synthetic hydrate-bearing sediments with different saturation were made as the in-situ hydrate. A series of triaxial shear tests were carried out on artificial hydrate bearing sediments with different hydrate saturation and confining pressure. The testing results showed that with the increasing of confining pressure and hydrate saturation, the compressive peak strength was enhanced, and the cohesion also increased, but internal frictional angle and Poisson ratio have no remarkable change. According to the experimental results and Morh-Coulomb Criterion, the semi-empirical mathematical model of the peak strength about different hydrate saturation and confining pressure was established, providing some supports for the selection of strength parameters of hydrate for deep-water hydrate drilling, and for the theoretical analysis and numerical simulation of laboratory experiments.