Experimental Study on Gas Production from Methane Hydrate-Bearing Sand by Hot-Water Cyclic Injection

A three-dimensional middle size reactor was used to simulate gas production from methane hydrate-bearing sand by hot-water cyclic injection The gas production process and energy efficiency in the whole process, which was divided into injecting hot water, closing well, and producing gas (three steps), were investigated using 16 thermocouples distributed in hydrate bearing sand samples The experimental results indicates that the overall temperature trend increases with hot water injection and decreases with gas production The temperature distribution and fluctuation in the reactor depend upon the location of the injecting/producing well as well as the porosity and permeability of hydrate samples Heat transfer is controlled by hot-water seepage flow during the injection of hot water The affecting factors on the energy efficiency, such as hydrate saturation, hydrate sample temperature, hot-water temperature, mass of hot water injected, and well pressure, were examined It was found that, when other conditions are similar, the energy efficiency ratio increases with the Increase of the hydrate-bearing sand saturation and hydrate sample temperature but decreases with the increase of the hot water temperature and well pressure