Evaluation of Hot-Brine Stimulation Technique for Gas Production From Natural Gas Hydrates

Abstract

Thermally efficient 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 efficiency. In addition, the problems of blockage of rock pores and wellbore because of reformation of hydrates during gas production can be avoided. A mathematical model for a hot-brine stimulation technique was developed to compute gas recovery and the energy-efficiency ratio (i.e., the ratio of energy content of produced gas to heat injected) for a reservoir containing gas hydrates. The effects of variations in reservoir porosity, hydrate-zone thickness, depth, salinity of brine, brine temperature, and brine injection rate on the energy-efficiency ratio and gas production were determined. A comparison of brine and steam injection cases for the same heat injection rate shows higher gas production and energy-efficiency ratio for the brine case.