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DOI	10.1029/2019JB018442
	Shale Anisotropy and Natural Hydraulic Fracture Propagation: An Example from the Jurassic (Toarcian) Posidonienschiefer, Germany
	Hooker J.N.; Ruhl M.; Dickson A.J.; Hansen L.N.; Idiz E.; Hesselbo S.P.; Cartwright J.
发表日期	2020
ISSN	21699313
卷号	125 期号:3
英文摘要	Cores recovered from the Jurassic (Toarcian) Posidonienschiefer (Posidonia Shale) in the Lower Saxony Basin, Germany, contain calcite-filled fractures (veins) at a low angle to bedding. The veins preferentially form where the shale is both organically rich and thermally mature, supporting previous interpretations that the veins formed as hydraulic fractures in response to volumetric expansion of organic material during catagenesis. Despite the presence of hydrocarbons during fracturing, the calcite fill is fibrous, and so, the veins appear to have contained a mineral-saturated aqueous solution as they formed. The veins also contain myriad host-rock inclusions having submillimetric spacing. These inclusions are strands of host rock that were entrained as the veins grew by separating the host rock along bedding planes rather than cutting across planes. The veins therefore produce significantly more surface area – by a factor of roughly 5, for the size of veins observed – compared to an inclusion-free fracture of the same size. Analysis of vein geometry indicates that, with propagation, a fracture surface area increases with fracture length raised to a power between 1 and 2, assuming linear aperture-length scaling. As such, this type of fracture efficiently dissipates elastic strain energy as it lengthens, stabilizing propagation and precluding dynamic crack growth. The apparent separation of the host rock along bedding planes suggests that the mechanical weakness of bedding planes is the cause of this inherently stable style of propagation. © 2020. The Authors.
英文关键词	calcite; fracture; Lower Saxony Basin; mudrock; Posidonienschiefer; shale
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/187917
作者单位	Department of Earth Sciences, University of Oxford, Oxford, United Kingdom; Department of Geosciences, Penn State University, State College, PA, United States; Irish Centre for Research in Applied Geosciences and Department of Geology, Trinity College Dublin, The University of Dublin, Dublin, Ireland; Department of Earth Sciences, Royal Holloway University of London, Egham, United Kingdom; Camborne School of Mines and Environment and Sustainability Institute, Penryn Campus, University of Exeter, Penryn, United Kingdom
推荐引用方式 GB/T 7714	Hooker J.N.,Ruhl M.,Dickson A.J.,et al. Shale Anisotropy and Natural Hydraulic Fracture Propagation: An Example from the Jurassic (Toarcian) Posidonienschiefer, Germany[J],2020,125(3).
APA	Hooker J.N..,Ruhl M..,Dickson A.J..,Hansen L.N..,Idiz E..,...&Cartwright J..(2020).Shale Anisotropy and Natural Hydraulic Fracture Propagation: An Example from the Jurassic (Toarcian) Posidonienschiefer, Germany.Journal of Geophysical Research: Solid Earth,125(3).
MLA	Hooker J.N.,et al."Shale Anisotropy and Natural Hydraulic Fracture Propagation: An Example from the Jurassic (Toarcian) Posidonienschiefer, Germany".Journal of Geophysical Research: Solid Earth 125.3(2020).