Thermal Stimulation Based Methane Production from Hydrate Bearing Quartz Sediment

Natural gas hydrates represent a potentially substantial unconventional natural gas resource and the recovery of permafrost hydrates has seen significant attention over the past decade. Laboratory study of different growth and dissociation methods is an important step in the development of gas hydrate production methods. The formation and dissociation behavior of gas hydrates in quartz sand sediment is investigated on a large laboratory scale reactor with a sample volume of 59.3 L. Hydrate saturations of 10% and 30% pore space volume are dissociated via a point source thermal stimulation method using both a low heating rate of 20 W and a high heating rate of 100 W. Hydrate growth via gas invasion method resulted in nonhomogenous hydrate formation. Secondary hydrate formation was observed during prolonged hydrate formation periods in a quasi-repeatable manner. Peak efficiency rates of gas production ranged from 91% to 72% and net end of test efficiencies from 86% to 41%. Higher initial hydrate saturations resulted in better production performance while greater heating rates resulted in higher peak efficiency rates. Higher hydrate saturations displayed heater temperature spikes followed by a transition zone where heater temperatures stabilized due to the onset of increased convective heat transport.