Impact of Partial Hydrate Dissociation on the Mechanical Properties of Methane Hydrate Bearing Coarse-Grained Sediments

Conventional methods for recovering methane gas from natural hydrate-bearing sand (HBS) involve dissociating the hydrate, impacting the mechanical properties of the HBS. Existing numerical models used for predicting ground behavior over long-term production are calibrated based on laboratory tests conducted after hydrate formation and not dissociation as limited research studies have been conducted to comprehensively understand the changes in HBS shear strength during dissociation. In this research, experiments were conducted on laboratory-synthesized HBS specimens that had undergone hydrate dissociation to varying degrees by thermal stimulation as well as depressurization revealing notable reductions in both stiffness and peak strength. These observed alterations in mechanical properties commenced within the confines of the bulk hydrate stability region, suggesting the influence of sediment grain size and pore diameter. Further studies aim to explore the other contributing factors to these observations.