Deformation and strength anisotropy of Asan gneiss, Boryeong shale, and Yeoncheon schist

Cho, Jung-Woo; Kim, Hanna; Jeon, Seokwon; Min, Kyoung-Bok

doi:10.1016/j.ijrmms.2011.12.004

Cited by 375 publications

(144 citation statements)

References 28 publications

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“…Cho et al conducted a series of uniaxial compression tests with Boryeong shale and other rocks to explore the deformation and strength anisotropy. With the results by Cho et al [19], we are able to know that the coefficient of anisotropy of strength of Boryeong shale is 0.58, reflecting that the anisotropy of the Boryeong shale is a little stronger than that of the Longmaxi …”

Section: Discussionsupporting

confidence: 50%

“…Furthermore, sample deformation will be relatively large when the load direction deviates from the bedding planes, indicating that shale has a lower stiffness under these anisotropy angles. A paper from Cho et al [19] reported the experimental investigation of deformation and strength anisotropy of Asan gneiss, Boryeong shale and Yeoncheon schist in Korea which have clear evidence of transverse isotropy. From the paper we learned that the change laws of Young's modulus with the angle of anisotropy of various layered rock are of great difference.…”

Section: Discussionmentioning

confidence: 99%

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Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

et al. 2016

Energies

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Abstract:With the exploitation of shale gas booming all over the world, more and more studies are focused on the core technology, hydraulic fracturing, to improve commercial exploitation. Shale gas resources in China are enormous. In this research, a series of tests were carried out with samples of black organic-rich shale from the Lower Silurian Longmaxi formation, south China. Samples were drilled from different directions and were subjected to uniaxial and triaxial condition with various confining pressures, aiming at studying its rock mechanics properties, so as to provide basis for research and breakthrough of hydraulic fracturing technology. According to the results of the study, the development and distribution of shale's bedding planes significantly impact its mechanical properties. Shale samples show obvious brittle characteristics under low confining pressure, and its mechanical behavior begins to transform from brittle to plastic characteristics with increasing confining pressure. Shale samples with different inclinations (β) have different sensitivities to the confining pressure. As a result, samples with 45 • inclinations (β) are least sensitive. The strength of bedding planes is significantly lower than that of shale matrix, and tensile failure and shear failure generally tend to occur along the bedding planes. When hydraulic fracturing was conducted in shale formation with depth less than 2.25 km, corresponding to original in-situ of 60 MPa, cracks will preferably occur at first along the inclination (β) angle of 45 • from the maximum principal stress, and the failure mode is most likely to be shear failure without volumetric strain. And, different modes of failure will occur at different locations in the reservoir, depending on the orientation of bedding inclined from the principle stress, which can probably explain the phenomenon why there are fractures along and cross the bedding planes during hydraulic fracturing treatment. When hydraulic fracturing was conducted in shale formation with depth greater than 2.25 km, hydraulic fractures may not crack along the bedding surfaces to some extent.

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Section: Discussionsupporting

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

et al. 2016

Energies

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“…일축압축 강도와 압열인장강도는 각각 3회의 실험결과에 대한 평 균치이며, 탄성정수는 방향별로 부착된 84개의 변형률 Table 3. Elastic constants of Asan gneiss (Cho et al, 2012) (Goodman, 1989). …”

Section: Gbm-udec 모델의 미시변수와 거시물성의 관계unclassified

Polygonal Grain-Based Distinct Element Modelling of Mechanical Characteristics and Transverse Isotropy of Rock

Park¹,

Park²,

Ryu³

et al. 2016

Tunnel and Underground Space

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This study presents a methodology to reproduce the mechanical behavior of isotropic or transversely isotropic rock using the polygonal grain-based distinct element model. A numerical technique to monitor the evolution of micro-cracks during the simulation was developed in the present study, which enabled us to examine the contribution of tensile cracking and shear cracking to the progressive process of the failure. The numerical results demonstrated good agreement with general observations from rock specimens in terms of the behavior and the evolution of micro-cracks, suggesting the capability of the model to represent the mechanical behavior of rock. We also carried out a parametric study as a fundamental work to examine the relationships between the microscopic properties of the constituents and the macroscopic behavior of the model. Depending on the micro-properties, the model exhibited a variety of responses to the external load in terms of the strength and deformation characteristics. In addition, a numerical technique to reproduce the transversely isotropic rock was suggested and applied to Asan gneiss from Korea. The behavior of the numerical model was in good agreement with the results obtained in the laboratory-scale experiments of the rock.

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“…Kim et al [27] has studied the thermal conductivity of the Asan gneiss and Boryeong shale, finding that the ratio of K PAR (thermal conductivity of parallel to bedding planes) to K PER (thermal conductivity of perpendicular to bedding planes) is 1.4, and the anisotropy of thermal conductivity in the shale is obvious. The wave velocity in a rock is usually used as a physical parameter [28,29] to predict the elastic modulus and thermal conductivity of rock. It is also affected by changes in the material and fracture development, with the wave velocity tending to decrease with an increase in temperature.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy in Thermal Recovery of Oil Shale—Part 1: Thermal Conductivity, Wave Velocity and Crack Propagation

et al. 2018

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Abstract:In this paper, the evolution of thermal conductivity, wave velocity and microscopic crack propagation both parallel and perpendicular to the bedding plane in anisotropic rock oil shale were studied at temperatures ranging from room temperature to 600 • C. The results show that the thermal conductivity of the perpendicular to bedding direction (K PER ) (PER: perpendicular to beeding direction), wave velocity of perpendicular to bedding diretion (V PER ), thermal conduction coefficient of parallel to beeding direction (K PAR ) and wave velocity of parallel to beeding direction (V PAR ) (PAR: parallel to bedding direction) decreased with the increase in temperature, but the rates are different. K PER and V PER linearly decreased with increasing temperature from room temperature to 350 • C, with an obvious decrease at 400 • C corresponding to a large number of cracks generated along the bedding direction. K PER , V PER , K PAR and V PAR generally maintained fixed values from 500 • C to 600 • C. 400 • C has been identified as the threshold temperature for anisotropic evolution of oil shale thermal physics. In addition, the relationship between the thermal conductivity and wave velocity based on the anisotropy of oil shale was fitted using linear regression. The research in this paper can provide reference for the efficient thermal recovery of oil shale, thermal recovery of heavy oil reservoirs and the thermodynamic engineering in other sedimentary rocks.

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Deformation and strength anisotropy of Asan gneiss, Boryeong shale, and Yeoncheon schist

Cited by 375 publications

References 28 publications

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

Polygonal Grain-Based Distinct Element Modelling of Mechanical Characteristics and Transverse Isotropy of Rock

Anisotropy in Thermal Recovery of Oil Shale—Part 1: Thermal Conductivity, Wave Velocity and Crack Propagation

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