화학공학소재연구정보센터
Chemical Engineering Science, Vol.134, 727-736, 2015
Influence of gas sweep on methane recovery from hydrate-bearing sediments
Gas sweep is favorable for reducing the partial pressure of methane in free gas during the production of methane from hydrate-bearing sediments. To evaluate the influence of gas sweep on methane recovery, pure N-2 was injected into hydrate-bearing sediments using a scale-up three-dimensional apparatus. The influences of injection mode, hydrate saturation, and N-2 injection rate were investigated. The experimental results suggest that the methane recovery rate by pure N-2 sweep is much quicker than direct depressurization. The driving force for hydrate dissociation increases with the increase of the N-2 mole fraction, which further promotes the decomposition of hydrates and guarantees a high gas production rate. In terms of N-2 injection rate on gas production, the higher the gas production, the more N-2 that is required, which means the increase of gas production rate is at the cost of injecting much more N-2. Compared with the continuous mode, the batch injection mode is more suitable for controlling the hydrate dissociation rate and may be the lower risk way for hydrate exploitation. The gas sweep method may supply a new strategy that would be helpful to make low saturation hydrate reservoirs become a technically recoverable resource. (C) 2015 Elsevier Ltd. All rights reserved.