Thermally eftlcient production of natural gas can be accomplished by the use of hot brine to dissociate solid gas hydrate deposits in the earth, The advantages of brine stimulation over steam or hot-water injection are lower energy requirements for reservoir heating and hydrate dissociation, reduced heat losses, higher gas production, and improved thermal eftlciency. In addition, the problems of blockage of rock pores and wellbore because of reformation of hydrates during gas producdon can be avoided.A mathematical model for a hot-brine stimulation technique was developed to compute gas recovery and the energy4ficiency ratio (i.e., the ratio of energj content of produced gas to heat injected) for a reservoir coutaitdng gas hydrates. The effects of variations in reservoir porosity, hydrate-zone thickness, depth, safinity of brine, brine temperature, and brine injection rate on the energy-efticieniy ratio and" gas production were determined. A comparison of brine and steam injection cases for the smie heat inje+ion rate shows bigber gas production and ener~eftlciency ratio for the brine case.

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The two most promising techniques for producing natural gas from hydrate reservoirs are depressurization and brine injection. This paper examines the dissociation characteristics of methane hydrates during these processes. A correlation for the rate of hydrate dissociation during brine injection as a function of salinity, brine temperature, brine injection rate, pressure, and hydratelbrine surface area is presented. Depressurization experiments show that hydrate dissociation results in a decrease in the rate of pressure decline and contributes significantly (15% to 70%) to the cumulative gas production.

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