A gas production system by injecting hot water into a methane hydrate layers with lower aquifer under the sea bottom has been studied using with horizontal wells in radial arrangements. In order to overcome extremely low permeability and large dissociation heat of the MH layer, the system forming dissociated chamber with high permeability and communication to lower aquifer has been proposed and evaluated by physical and numerical models. The numerical simulations were successfully matched with experiments using the physical model. Moreover, numerical simulations of gas production by the hot water injection into a field of methane hydrate sediment using dual horizontal wells 500 m in length were carried out for a methane hydrate reservoir of 15m in layer thickness, 60% of hydrate saturation, 100 and 25 md in horizontal and vertical absolute permeabilities, respectively. In this study, after getting communication between hot water chamber and lower aquifer, a gas production scheme for the area of 1km×1km has been proposed by using radial flow between different horizontal well pair through lower aquifer. At the beginning, dual horizontal wells was preheated by hot water circulation in the wells for 90 days to get communication of area between two horizontal wells. After gas production with four pairs of dual wells for one year, radial hot water flow can be used to make the chamber expand in horizontal section of the reservoir. The simulations were performed under the following conditions: hot water temperature of 85°C, injection rate of 2000 ton/day, horizontal wells 500 m in length, and a hydrate layer 15m in thickness with vertical absolute permeability of 25 md horizontal one of 100 md and methane hydrate saturation of 60%. The cumulative gas production during 15 years, it was estimated as 1.3×108 std-m3 during 15 years by using with the injection scheme with radial hot water flow between different wells pair after one year.

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