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DOI	10.1016/j.earscirev.2019.102957
	Stress concentrations and failure modes in horizontal wells accounting for elastic anisotropy of shale formations
	Weijermars R.; Wang J.; Nelson R.
发表日期	2020
ISSN	00128252
卷号	200
英文摘要	This study presents a systematic analysis of stress changes near the horizontal well sections drilled in shale and clay formations using a new approach. Most of the prior analyses of stress concentrations and wellbore stability in anisotropic shale formations use the traditional Lekhnitskii-Amadei solutions. We present a faster set of analytical stress functions, based on largely overlooked solutions by Green and Taylor. First the full theoretical range of possible compliances for transverse isotropic materials is evaluated, using data for 5 shale/clay samples and 12 additional test materials. Contour plots show the principal stress trajectory patterns and variation in the spatial stress concentration due to deviation from isotropic elasticity. Next, we show how uni-axial far-field stress solutions can be mutually superposed and combined with stress function solutions for local stress concentration due to internal pressure on the wellbore. The reappraised set of Green and Taylor equations is then applied to horizontal wells in three Andersonian stress states for compressional, strike-slip and extensional basins. The stress concentrations in the horizontal wellbore are evaluated for well depths between 0 and 10,000 ft, using the elastic stiffnesses from five shale and clay samples to show the stress deviations from the isotropic reference case. Finally, a full wellbore stability evaluation model combines the stress concentrations around the wellbore with failure criteria, to determine the safe drilling window at each well depth (for each Andersonian stress state). Practical graphs and supporting equations are provided to assess wellbore stability in transverse isotropic shale. © 2019 Elsevier B.V.
关键词	Anisotropy Elastic deformation Safe drilling window Shale drilling Wellbore stability
英文关键词	anisotropy; borehole stability; deformation; elasticity; failure mechanism; oil shale; shale gas; stiffness; stress analysis; transverse isotropy; Andersonia
语种	英语
来源期刊	Earth Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203926
作者单位	Harold Vance Department of Petroleum Engineering, Texas A&M University, 3116 TAMU, College Station, TX 77843-3116, United States; Department of Petroleum and Natural Gas Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, United States; Department of Earth Resources and Environmental Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul, 04763, South Korea; Department of Earth Science and Engineering, Imperial College London, 180 Queen's Gate, London, SW7 2AZ, United Kingdom
推荐引用方式 GB/T 7714	Weijermars R.,Wang J.,Nelson R.. Stress concentrations and failure modes in horizontal wells accounting for elastic anisotropy of shale formations[J],2020,200.
APA	Weijermars R.,Wang J.,&Nelson R..(2020).Stress concentrations and failure modes in horizontal wells accounting for elastic anisotropy of shale formations.Earth Science Reviews,200.
MLA	Weijermars R.,et al."Stress concentrations and failure modes in horizontal wells accounting for elastic anisotropy of shale formations".Earth Science Reviews 200(2020).