Dual-Gas Coproduction via Depressurization for Methane Hydrate Under Semiadiabatic Heat Transfer Boundary Conditions

Abstract

This study simulates constrained heat transfer processes in natural environments by establishing a semiadiabatic boundary during methane hydrate formation and dissociation, utilizing an apparatus insulated with materials of low thermal conductivity. Within this semiadiabatic framework, the decrease in system temperature induced by heat absorption during hydrate decomposition cannot be promptly compensated by external heat sources. These results in reduced gas production rates and a lower proportion of gas deriving from hydrate dissociation compared to that observed with an isothermal boundary. The proportion of gas from hydrate dissociation in the produced gas in the semiadiabatic system was lower than that in the isothermal boundary, especially in the early and middle stages. The observed differences in hydrate dissociation behaviors between semiadiabatic and isothermal conditions provide critical insights into the interpretation of experimental studies and their applicability to natural hydrate reservoirs. These findings suggest implications for translating laboratory results into practical strategies for the exploitation of hydrate resources.