The mechanical evolution of hydrate-bearing sediments during natural gas extraction significantly impacts reservoir stability. This study employs an integrated experimental approach to investigate the mechanical and acoustic behavior of hydrate-bearing sands under external loading. Using a modified high-pressure low-temperature triaxial apparatus equipped with ultrasonic monitoring, we systematically examined wave velocity evolution, disturbance characteristics, and Poisson’s ratio variations during different testing stages. The experimental results reveal several key findings: during hydrate formation, the sediment Poisson’s ratio decreases progressively, while disturbance variables derived from both compressional and shear wave velocities show continuous increase. The mechanical response characteristics under varying stress conditions and hydrate saturation levels demonstrate clear correlations between acoustic properties and triaxial mechanical behavior. Furthermore, dynamic elastic parameters calculated from wave velocity data enable the determination of sand production indices, allowing a preliminary assessment of sand production probability across different stages. Analysis indicates that sand production risk evolves from high to low during hydrate formation, while remaining relatively low during consolidation and shearing stages. These findings provide theoretical insights for understanding mechanical behavior and stability evaluation in hydrate-bearing reservoirs, offering valuable references for gas production operations.
Huang et al. (Fri,) studied this question.