Hydrate decomposition and sand production during depressurization can degrade reservoir mechanical stability and threaten safe gas hydrate exploitation. This study uses discrete element method (DEM) simulations to examine how hydrate saturation, bonding strength, and sand production affect the mechanical behaviour of gas hydrate reservoirs. The results show that reduced hydrate saturation markedly decreases stiffness, peak strength, cohesion, and internal friction angle, while changing failure from shear-dominated to more ductile behaviour. When saturation decreases from 40% to 0%, the deformation modulus at 1 MPa confining pressure drops from 136.6 to 44.8 MPa, and peak strength decreases from 3.99 to 0.95 MPa. Weakened bonding strength also lowers peak strength and cohesion and alters shear band development. Increased sand production further reduces stiffness and strength, accelerates bond breakage, and compromises reservoir integrity. These findings emphasize the importance of controlled depressurization and effective sand control during hydrate exploitation.
Jia et al. (Thu,) studied this question.