DEM Study of Hydrate-Bearing Sediments Under Variable Hydrate Initial Saturation and Dissociation Ratio

Natural gas hydrate is a promising energy resource. However, the dissociation of hydrates during exploitation poses a significant risk of reservoir instability. A thorough understanding of the mechanical behavior of hydrate-bearing sediments (HBS) during hydrate dissociation is essential for the safe and efficient exploitation of this resource. In this study, we employed the discrete element method to numerically investigate the shear test results of HBS with varying initial hydrate saturations and dissociation ratios. A key innovation of our work is the finding that specimens with higher initial hydrate saturation are more susceptible to the mechanical effects of hydrate dissociation. The microscopic parameters of specimens with different initial hydrate saturations and their corresponding dissociation ratios can be described by a new unified function. Both hydrate saturation and dissociation path significantly affect the mechanical behavior of HBS, and these two factors must be considered simultaneously when constructing relevant constitutive models. This study offers new theoretical insights and provides important reference values for the future development of accurate constitutive models for HBS.