Anisotropic time-dependent behaviors of shale under direct shearing and associated empirical creep models

Xie, Yachen; Hou, Zhengmeng; Liu, Hejuan; Li, Cunbao

doi:10.1016/j.jrmge.2023.05.001

Cited by 14 publications

(2 citation statements)

References 48 publications

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“…It can be observed from the figure that the strain-time curves exhibit clear initial attenuation and steady flow under a 50% stress level, and the creep deformation is small. For the sample that failed under 80% or 95% stress levels, the strain-time curves exhibited three distinct phases: decelerating, steady-state, and accelerating creep stages (Xie et al, 2023). The reason for this phenomenon is that the creep deformation of the brittle rock reflects the motion of defects in the crystalline structure within the constituent minerals and stable microfracturing (Brantut et al, 2013;Zhang et al, 2012).…”

Section: Strain-time Curvesmentioning

confidence: 99%

Creep behavior of sandstone under the coupling action of stress and pore water pressure using three-dimensional digital image correlation

Chen,

Xie,

et al. 2023

International Journal of Damage Mechanics

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Understanding the damage evolution and time-dependent property of rock creep is of great significance for predicting geohazards and evaluating the long-term stability of geotechnical structures. In this study, a three-dimensional digital image correlation system was adopted to investigate the creep behavior of sandstone under the coupling action of stress and pore water pressure. The apparent strain fields, deformation characteristics of the localization zone, and micromorphology of the fracture surface were analyzed. The results demonstrated that when the applied deviatoric stress level was above σci (crack initial stress) or σcd (crack damage stress), the increase in pore water pressure promoted creep deformation evidently, improved the creep rate significantly and shortened the time-to-failure of the rock obviously. In the radial strain field, the localized development of substantial microcracks on the rock surface was concentrated in the steady-state creep, while the microcracks interconnected to form macroscopic shear cracks that dominated the accelerating creep, and this damage evolution characteristic can be used as a precursor and early warning of rock creep failure. Besides, increasing the pore water pressure also would cause the divergence point of strain curves inside and outside the localization zone to appear earlier at the secondary creep, and produce a wider localization zone at the tertiary creep. The creep fracture surface of the rock was dominated by intergranular microcracks. Increasing the pore water pressure would result in the deterioration of the cemented structure and breakage of the cemented matrix more seriously, thus stimulating the generation of more microcracks.

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Section: Strain-time Curvesmentioning

confidence: 99%

Creep behavior of sandstone under the coupling action of stress and pore water pressure using three-dimensional digital image correlation

Chen,

Xie,

et al. 2023

International Journal of Damage Mechanics

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“…Hydraulic fracturing (HF) is a pivotal technology for the stimulation of geoenergy reservoirs [1][2][3]. Nonetheless, for fracturing operations in deep reservoirs, several common challenges arise, such as the higher breakdown pressure (BP), the creation of a singular fracture network, and the lower mining efficiency [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Non-Uniform Minerals Distribution on Hydraulic Fracture Evolution during Unconventional Geoenergy Exploration

Gao,

Li,

et al. 2023

Processes

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To study the effect of the non-uniform distribution of minerals on the development of microcracks within the rock during hydraulic fracturing, a novel numerical model considering multiple random mineral distributions was designed. The model investigated the impacts of mineral grain size, composition, and spatial arrangement on fracture initiation and propagation. The results indicate that the presence of the hard-phase mineral quartz can alter the propagation path of fractures, and increase the width of hydraulic fractures. In coarse-grained granite, the range of crack deflection is maximized, while in medium-grained granite, it is more prone to forming convoluted elongated cracks. A higher quartz content in granite further contributes to the formation of complex crack networks. Simultaneously, the evolution of granite fractures and variations in breakdown pressure in heterogeneous granite were investigated, considering the influence of core parameters such as fluid injection rate, fracturing fluid viscosity, and horizontal stress difference. The research reveals that a high injection rate promotes straight-line fracture expansion. Moreover, modest fluctuations in fracturing fluid viscosity have minimal effects on fracture morphology. When the fracture development avoids quartz, under the influence of high horizontal stress differential, it clearly turns toward the direction of the maximum principal stress. This study can offer insights into innovative and optimized deep reservoir fracturing techniques.

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A true triaxial creep constitutive model of rock considering the coupled thermo-mechanical damage

Tong,

Chen,

Chen

et al. 2023

Energy

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Anisotropic time-dependent behaviors of shale under direct shearing and associated empirical creep models

Cited by 14 publications

References 48 publications

Creep behavior of sandstone under the coupling action of stress and pore water pressure using three-dimensional digital image correlation

Creep behavior of sandstone under the coupling action of stress and pore water pressure using three-dimensional digital image correlation

Effect of Non-Uniform Minerals Distribution on Hydraulic Fracture Evolution during Unconventional Geoenergy Exploration

A true triaxial creep constitutive model of rock considering the coupled thermo-mechanical damage

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