Mechanism of Hydrate Decomposition Influenced by Reservoir Structural Characteristics Around Hydrate Wells

As a future abundant and environmentally friendly clean energy source, the decomposition process of natural gas hydrates is significantly regulated by reservoir structural characteristics. Improper extraction can easily trigger geological hazards, yet current research on the coupling mechanism between wellbore microstructure and decomposition remains incomplete. To elucidate the regulatory role of reservoir structural characteristics, this study employed a self-developed physical simulation system to conduct triaxial creep experiments. It compared the mechanical response and decomposition dynamics of sediments under layered and homogeneous hydrate distribution patterns, while simultaneously monitoring gas production and formation displacement parameters. Results indicate that layered distribution significantly influences overall sediment creep behavior and failure patterns: low-saturation sublayers dominate the creep softening–hardening mechanism, while strain evolution at different timescales and long-term bearing capacity are controlled by low- and high-saturation sublayers, respectively. Creep cohesion and internal friction angle exhibit distinct differences between the two distribution patterns, with the influence mechanisms of relevant mechanical indicators closely related to the roles of sublayers with varying saturations. The study also uncovers the intrinsic link between gas production and stratigraphic subsidence during hydrate decomposition, clarifying the core mechanism by which reservoir structures influence decomposition stability through regulating mechanical responses. The methodologies and conclusions of this research provide scientific support for predicting the long-term stability of natural gas hydrate reservoirs and enabling safe, efficient extraction, while laying the groundwork for the systematic development of comprehensive hydrate technologies.