Enhancing Hydrate Exploitation from Reservoirs by Depressurization Combined with Electrical Resistance Heating

Natural gas hydrate (NGH) production by depressurization can be constrained by the temperature decline associated with endothermic hydrate dissociation and the resulting potential for secondary hydrate formation. To address these limitations, this study investigates electrical resistance heating (ERH), which generates Joule heat within hydrate-bearing sediments. A laboratory-scale electrical–thermal–hydraulic–chemical (ETHC) coupled model is developed, incorporating Joule heating, multiphase flow, heat transfer, and hydrate dissociation kinetics. Following validation against the Masuda core experiment, three production scenarios are compared: depressurization alone (Case A), depressurization combined with ERH (Case B), and depressurization combined with ERH and external thermal replenishment (Case C). Under a constant external boundary temperature of 273.15 K, gas production in Case A declines rapidly as dissociation-induced cooling inhibits further hydrate dissociation. ERH in Case B promotes dissociation within the core, although the same boundary temperature continues to constrain dissociation near the periphery. In Case C, raising the external boundary temperature to 280.15 K alleviates this constraint and promotes more spatially extensive hydrate dissociation. Compared with Case B, Case C increases the peak gas production rate by 64% and accelerates the dissociation process. These results clarify the combined effects of internal Joule heating and external thermal replenishment on hydrate dissociation under idealized laboratory-scale thermal boundary conditions.