气候变化领域集成服务门户(CCPortal): Fluid-Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure

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DOI	10.1029/2019JB018971
	Fluid-Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure
	Gehne S.; Forbes Inskip N.D.; Benson P.M.; Meredith P.G.; Koor N.
发表日期	2020
ISSN	21699313
卷号	125 期号:2
英文摘要	A number of key processes, both natural and anthropogenic, involve the fracture of rocks subjected to tensile stress, including vein growth and mineralization, and the extraction of hydrocarbons through hydraulic fracturing. In each case, the fundamental material property of mode-I fracture toughness must be overcome in order for a tensile fracture to propagate. While measuring this parameter is relatively straightforward at ambient pressure, estimating fracture toughness of rocks at depth, where they experience confining pressure, is technically challenging. Here we report a new analysis that combines results from thick-walled cylinder burst tests with quantitative acoustic emission to estimate the mode-I fracture toughness (KIc) of Nash Point Shale at confining pressure simulating in situ conditions to approximately 1-km depth. In the most favorable orientation, the pressure required to fracture the rock shell (injection pressure, Pinj) increases from 6.1 MPa at 2.2-MPa confining pressure (Pc), to 34 MPa at 20-MPa confining pressure. When fractures are forced to cross the shale bedding, the required injection pressures are 30.3 MPa (at Pc = 4.5 MPa) and 58 MPa (Pc = 20 MPa), respectively. Applying the model of Abou-Sayed et al. (1978, https://doi.org/10.1029/JB083iB06p02851) to estimate the initial flaw size, we calculate that this pressure increase equates to an increase in KIc from 0.36 to 4.05 MPa·m1/2 as differential fluid pressure (Pinj − Pc) increases from 3.2 to 22.0 MPa. We conclude that the increasing pressure due to depth in the Earth will have a significant influence on fracture toughness, which is also a function of the inherent anisotropy. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Fracture Toughness; Shale; Tensile Fracture
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187953
作者单位	Rock Mechanics Laboratory, School of Earth and Environmental sciences, University of Portsmouth, Portsmouth, United Kingdom; Lyell Centre, Heriot-Watt University, Edinburgh, United Kingdom; Rock and Ice Physics Laboratory, Department of Earth Sciences, University College London, London, United Kingdom
推荐引用方式 GB/T 7714	Gehne S.,Forbes Inskip N.D.,Benson P.M.,et al. Fluid-Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure[J],2020,125(2).
APA	Gehne S.,Forbes Inskip N.D.,Benson P.M.,Meredith P.G.,&Koor N..(2020).Fluid-Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure.Journal of Geophysical Research: Solid Earth,125(2).
MLA	Gehne S.,et al."Fluid-Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure".Journal of Geophysical Research: Solid Earth 125.2(2020).