Effect of depressurization pressure on methane recovery from hydrate–gas–water bearing sediments. (15th February 2016)

• Record Type: Journal Article
• Authors: Yang, Mingjun; Fu, Zhe; Zhao, Yuechao; Jiang, Lanlan; Zhao, Jiafei; Song, Yongchen
• Is Part Of: Fuel. Volume 166(2016)
• Page Start: 419
• Page End: 426
• Publication Date: 2016-02-15
• Subjects: Natural gas hydrate -- Depressurization -- Methane gas recovery -- Porous media; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2015.10.119
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: MH dissociation characters were measured for ternary phases sediment. Heat transfer is a control factor for MH dissociation pattern and rate. There is a maximum depressurization range to make MH dissociation rate increase. Methane gas seepage makes liquid water distribution changes. Abstract: Natural gas hydrates (NGHs) are a promising energy source with huge reserves. The dissociation characteristics of NGHs need to be clarified further for developing safe and efficient technology for its recovery. In this study, Classes 1 and 2 NGH deposits were simulated by forming methane hydrate (MH) in porous media, and MH dissociation induced by depressurization was investigated using magnetic resonance imaging (MRI). MRI showed the liquid water distribution, which was used to analyze MH formation and dissociation. The vessel pressure was also measured during the experiments, which was compared with the MRI mean intensity of liquid water. MH dissociation processes were measured and analyzed under different backpressures, from 2.2 to 2.8 MPa. It was observed that liquid water hindered methane gas output during gas production; hydrate dissociation caused the movement of some liquid water, which usually led to fluctuations in MRI signal intensity. The experimental results also indicated that the MH dissociation pattern was affected by heat transfer; although a larger depressurization range led to faster dissociation, the average dissociation rate was controlled by heat transfer.