Fracture network stimulation effect on hydrate development by depressurization combined with thermal stimulation using injection-production well patterns. (1st August 2021)

• Record Type: Journal Article
• Authors: Zhong, Xiuping; Pan, Dongbin; Zhu, Ying; Wang, Yafei; Zhai, Lianghao; Li, Xitong; Tu, Guigang; Chen, Chen
• Is Part Of: Energy. Volume 228(2021)
• Publication Date: 2021-08-01
• Subjects: Natural gas hydrate -- Fracture network -- Depressurization combined thermal stimulation -- Stimulation effect; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2021.120601
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: In this study, the stimulation effect of the fracture network on hydrate development by depressurization combined with hot water injection (D + Tiw ) utilizing injection-production well patterns was explored and the key fracture properties' influences on stimulation effect were investigated. The results showed that D + Tiw significantly improved hydrate decomposition, but has a minimal enhancement on CH4 production owing its extremely low CH4 recovery ratio. The fracture network improved CH4 production of D + Tiw significantly. Water breakthrough of production wells has a strong influence on D + Tiw development performance; and, divided the influence of fracture conductivity on hydrate development into two opposite stages. The change in fracture spacing caused a hydrate decomposition mode transformation. Under larger fracture spacing, hydrate decomposition occurred in the piston-like decomposition mode and the effect of fracture spacing on hydrate development performance was minimal. However, when fracture spacing was small enough to transform the hydrate decomposition into a non-piston-like decomposition mode, hydrate decomposition and CH4 production rate increased sharply. Highlights: A fracture network-assisted hydrate mining scheme is firstly proposed. Horizontal fractures significantly improve mining while the vertical is useless. Water breakthrough of production wells severely inhibits hydrate mining behaviour. Fracture spacing converts hydrate dissociation mode, dramatically impacting mining.