Numerical modeling and analysis of production capacity in natural gas hydrate extraction via depressurization

This research develops a comprehensive physical-mathematical framework for modeling gas hydrate dissociation dynamics under depressurization conditions in cylindrical reservoir systems. The coupled thermo-hydro-mechanical-chemical (THMC) model integrates multiphase flow equations, phase transition kinetics, and geomechanical responses, calibrated using field monitoring data (including wellhead pressure, temperature transients, and gas production rates) from China’s inaugural offshore hydrate trial production in the Shenhu Area, South China Sea (2017). Key findings demonstrate: (1) A pressure-depression funnel forms around the well with maximum pressure drop near the wellbore; (2) The dissociation zone expands radially over time; (3) Lower bottom-hole pressure increases peak gas production and cumulative output; (4) Higher initial saturation causes earlier peak production followed by rapid decline; (5) Enhanced permeability extends low-pressure zone propagation; (6) Larger kinetic constants improve gas production efficiency.