Micro and Nano-Size Pore Characteristics of Clay Minerals in a Shale Reservoir of the Longmaxi Formation in the Middle and Upper Yangtze Area, China

Han, Yufu; Chen, Shangbin; Zhu, Yanming; ZhaoxiZuo,; Zhou, Shuai

doi:10.1166/jnn.2017.14422

Cited by 2 publications

(1 citation statement)

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“…The clay content of Yibin Wufeng, Qainjiang Longmaxi, and Fuling Longmaxi ranges from 12% to 35% and that of Yan'an Yanchang ranges from 39% to 61%. The clay contents of marine and terrestrial shale reported range from 3.4% to 48.9% and from 10.8% to 67.5%, respectively (Xiong et al, ; Gao & Hu, ; Han et al, ). The results shown in Table are consistent with those reported in the literature.…”

Section: Methodsmentioning

confidence: 99%

Effect of Clay and Organic Matter Content on the Shear Slip Properties of Shale

Wang

et al. 2019

JGR Solid Earth

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Shale gas reservoirs contain a large number of natural fractures. When shear slip occurs during hydraulic fracturing, it will increase reservoir permeability and improve the reservoir stimulation performance. Because shale contains a large amount of clay and organic matter, its shear slip behavior differs from that of other rocks. In this study, the shear behavior of different shale blocks is experimentally studied, and the proportion of clay and organic matter in the shale dominates the shear slip behavior. Specifically, the friction coefficient and shear strength decrease with the increasing content of clay and organic matter. A microscopic support model was developed to describe the different shear slip behaviors for different contents of clay and organic matter. When the clay and organic matter content is lower than a critical threshold (~35%), shale is microscopically grain supported and brittle shear occurs and the material is prone to shear dilation. When this content is greater than a critical content (~43%), the microscopic structure is a matrix‐supported fabric and plastic shear occurs, which is prone to shear contraction. Shale with contents between these two critical thresholds has a mixed‐support fabric, which is a transition type between brittle and plastic shear. If the proportion of clay and organic matter is less than ~35%, the natural fracture tends to dilate and retain a certain degree of opening after shearing, improving stimulation performance. When the proportion is more than ~43%, shear contraction occurs on the natural fracture surface, which is not conductive and cannot increase reservoir permeability.

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Section: Methodsmentioning

confidence: 99%