Hydrate dissociation and mechanical properties of hydrate-bearing sediments under local thermal stimulation conditions

Considering the interaction between hydrate dissociation and the mechanical properties of hydrate-bearing sediment (HBS) facilitates a deep understanding of the relationship between hydrate extraction efficiency and reservoir stability during hydrate exploitation. In this study, a series of tests were carried out to study the effects of hydrate dissociation under local thermal stimulation and the mechanical properties of HBS by using the plane strain shear test apparatus. The characteristics of the local maximum shear strain and volumetric strain were also investigated using the particle tracking velocimetry (PTV) method. The results show that the tested watersaturated host sands have the same heat transfer characteristics under local thermal stimulation, despite having different particle size distributions and mineral compositions. The temperature transfer inside the HBS was slower than that of the host sand sample, and the temperature distribution of the HBS after hydrate dissociation was the same as that of the host sand sample. HBS under an axial loading force higher than that of the peak strength of the host sand would fail after hydrate dissociation. Additionally, even partial dissociation of the hydrate can lead to catastrophic failure of HBS under this condition.