Analysis of the Mechanical Properties of the Reconstituted Hydrate-Bearing Clayey-Silt Samples from the South China Sea

Mechanical properties of hydrate-bearing sediments (HBS) are crucial for evaluating drilling- and production-induced geo-hazards. However, investigations on mechanical behaviors of clayey-silt samples containing hydrate are insufficient due to low efficiency in preparing reconstituted hydrate-bearing samples. Herein, we carried out a series of triaxial shear tests to analyze the deformation behaviors of reconstituted clayey-silt samples containing tetrahydrofuran (THF) hydrate. The sediments were taken from the Shenhu Area, northern South China Sea. The failure mechanisms during shearing are discussed based on micro-to-macro analyses. The results imply that the stress-strain curves show obvious strain-hardening under triaxial shearing, which can be divided into elastic deformation stage, transitional stage, and plastic deformation stage. Besides, the results reveal that cohesion strengthens from 0.09 MPa to 1.28 MPa when hydrate saturation increases from 15% to 60%. Moreover, calculation models are proposed to evaluate failure strengths and Young's modulus. Establishing empirical formula based on experimental data can quickly determine the strength parameters with knowing the hydrate saturation and stress state of clayey-silt sediments containing hydrate. It is urgent in field operations and numerical simulation to use reliable empirical models.

Automated summary

This study analyzed the mechanical properties of clayey-silt samples containing tetrahydrofuran hydrate through triaxial shear tests. The stress-strain curves exhibited strain-hardening under shearing and could be divided into elastic deformation, transitional stage, and plastic deformation. The cohesion increased with hydrate saturation. Calculation models were proposed to evaluate failure strengths and Young's modulus using experimental data.