Estimating Mechanical Parameters of Hydrate-Bearing Sediments on Basis of Shear Wave Velocity Under Triaxial Compression

The strength parameters of hydrate-bearing sediments (HBS) are vital to geological risk assessment and control during drilling and production operations. However, current publications mainly focus on the laboratory evaluation of strength parameters through triaxial compression, generating results intrinsically deviating from those obtained through petrophysical modeling. In this study, we developed an integrated apparatus that can simultaneously measure wave velocity and the mechanical behaviors of HBS under triaxial compression conditions. A series of experiments were conducted to analyze correlations between wave velocities and strength parameters. Results reveal that the P- and S-wave velocities considerably increase with hydrate saturation and are affected by effective confining pressure. Failure strength and elastic modulus are correlated with P-wave velocity. Finally, semi-empirical models are developed to predict strength parameters based on P-wave velocity and extended to establish longitudinal profiles for strength parameters of hydrate reservoirs in the Nankai Trough. This study offers insights into the acoustic properties of HBS under stress states for the prediction of mechanical parameters during natural gas hydrate development.