Identification and Extension of an Advanced Gas Hydrate Sediment Constitutive Model Using the Autocalibration Technique

Abstract

Energy extraction from gas hydrate sediments in marine environments significantly affect the seafloor stability, as these hydrates get perturbed from their thermodynamically stable conditions. Therefore, understanding the geomechanical behavior of gas hydrate sediment is critical for safe and economical energy extraction. In this study, the predictive accuracy of advanced elastoplastic constitutive models, including the methane hydrate Mohr–Coulomb model, the hierarchical single-surface methane hydrate (HISS-MH) model, and the hydrate clay and sand model, was evaluated using the autocalibration technique. Model parameters were autocalibrated using particle swarm optimization, with predictions compared to the drained triaxial compression experimental results across various pore morphologies and hydrate saturation levels (on both laboratory and field specimens). The comparative analysis reveals that the HISS-MH model accurately captures the critical aspects of the material response, such as strain-softening due to hydrate degradation and the variations in deviatoric stress and volumetric strain behavior. The error analysis further indicates that the HISS-MH model predictions align more with the actual material behavior, even under large deformation conditions. Further, the HISS-MH model was extended to include the effects of pore pressure and temperature by introducing a phase parameter in the yield function. These findings highlight the HISS-MH model’s superior capability to simulate the mechanical behavior of hydrate sediments, providing valuable insights for its implementation in numerical simulators to efficiently solve complex boundary value problems.