Geometrical description and permeability calculation about shale tensile micro-fractures

Qu, Guanzheng; Qu, Zhanqing; Hazlett, Randy; Freed, David; Mustafayev, Rahman

doi:10.1016/s1876-3804(16)30014-3

Cited by 21 publications

(13 citation statements)

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“…Results show that well A, B, and C have an average fracture half‐length of 79.6, 76.3, and 86.7 m, respectively (Figure 3b) and an average aperture width of 0.0252, 0.0246, and 0.0253 mm, respectively. According to the tensile fracture permeability formula between fracture permeability and fracture aperture (Qu et al., 2016), the fracture permeability is estimated to be approximately 9.87 × 10 −14 m 2 , in sharp comparison with the shale matrix permeability of only 4.11 × 10 −19 m 2 (from core analysis). This calculation result would be introduced into the following poroelastic simulation to describe the permeability changes surrounding horizontal wellbores.…”

Section: Resultsmentioning

confidence: 97%

Investigation on Two M_w 3.6 and M_w 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta

et al. 2021

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Recent evidence suggests that the increasing earthquakes in North America have been ascribed to industrial activities for resource development, including wastewater disposal, fluid production, geothermal systems, and hydraulic fracturing operations (Atkinson et al., 2016). It is believed that many induced earthquakes with the moment magnitude of M w larger than three in Western Canada are spatiotemporally related to the hydraulic fracturing (HF) activities in the area.

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Section: Resultsmentioning

confidence: 97%

Investigation on Two M_w 3.6 and M_w 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta

et al. 2021

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“…In this study, the tortuosity is defined as the ratio of the length of the path and the distance between its ends along z-axis [52] (Figure 14). Specific surface area (the surface area per bulk unit volume) and tortuosity are important macroscopic pore structure parameters of porous material [48][49][50], which can reflect structural properties of the cracks in shale [51]. In this study, the tortuosity is defined as the ratio of the length of the path and the distance between its ends along z-axis [52] (Figure 14).…”

Section: Quantitative Characterization Of Cracksmentioning

confidence: 99%

Mechanical Property Measurements and Fracture Propagation Analysis of Longmaxi Shale by Micro-CT Uniaxial Compression

et al. 2018

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The mechanical properties and fracture propagation of Longmaxi shale loading under uniaxial compression were measured using eight cylindrical shale specimens (4 mm in diameter and 8 mm in height), with the bedding plane oriented at 0 • and 90 • to the axial loading direction, respectively, by micro computed tomography (micro-CT). Based on the reconstructed three-dimensional (3-D) CT images of cracks, different stages of the crack growth process in the 0 • and 90 • orientation specimen were revealed. The initial crack generally occurred at relatively smaller loading force in the 0 • bedding direction specimen, mainly in the form of tensile splitting along weak bedding planes. Shear sliding fractures were dominant in the specimens oriented at 90 • , with a small number of parallel cracks occurring on the bedding plane. The average thickness and volume of cracks in the 90 • specimen is higher than those for the specimen oriented at 0 • . The geometrical characterization of fractures segmented from CT scan binary images shows that a specific surface area correlates with tortuosity at the different load stages of each specimen. The 3-D box-counting dimension (BCD) calculations can accurately reflect crack evolution law in the shale. The results indicate that the cracks have a more complex pattern and rough surface at an orientation of 90 • , due to crossed secondary cracks and shear failure.Various experimental methods, e.g., electromagnetic radiation (EMR), acoustic emission (AE), micro-seismic (MS), infrared technique, high speed digital imaging, and computerized tomography (CT), have been used to analyze the mechanical behavior of rocks (including shale) during uniaxial or triaxial loading [15][16][17][18][19][20][21]. CT scanning has been widely applied in the investigation of damage propagation since 1997, due to the three-dimensional (3-D) visualization and high-resolution imaging [22][23][24][25][26][27][28]. Kawakata et al. used CT to study the initial mesoscopic damage characteristics of rock materials, and observed spatial fault development in granite undergoing compression [29,30]. In the experiment, only the damaged specimens, rather than the entire process from crack initiation to specimen destruction, were scanned, and then observed by 3-D reconstruction of X-ray CT images. To examine the entire process, Ge et al. investigated rock compression with a real-time CT test [23]. Through the use of the industrial CT images, the rock meso-damage propagation law was revealed. Rock failure started with micro-pore and micro-crack compression, growth, bifurcation, and development, followed by fracture. Sun et al. displayed real-time deformation in backfill body under loading using industrial CT in several slices, and provided insights into the process of faulting [31]. However, the relatively low spatial resolution and image quality of conventional industrial CT is not suitable for fine-grained rocks. Furthermore, the 3-D information was not fully captured or used, which limited the accuracy of further calculation ...

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“…There is almost no report of taking dip angle alone to describe the characteristics of fracture surface morphology, and it is generally used in combination with other parameters. During the study of gas flow in shale micro-fracture, dip angle combined with other parameters were employed to fit shale gas flow, and the results showed that dip angle had an inhibitory effect on gas flow in shale micro-fracture [44].…”

Section: Tortuositymentioning

confidence: 99%

Characteristics Description of Shale Fracture Surface Morphology: A Case Study of Shale Samples from Barnett Shale

Tao

Zhang

et al. 2022

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Shale reservoirs are the hot issue in unconventional resources. The key to the development of shale reservoirs lies in the complex fractures, which are the only path for fluid to migrate from the matrix to the wellbore in shale reservoirs. Therefore, the characteristics of shale fracture surface morphology directly affect fluid migration in shale reservoirs. However, there are few reports about the characteristics of shale fracture surface morphology as the parallel plate model was commonly used to characterize the fracture, neglecting its surface morphology characteristics and leading to great deviation. Thus, description methods were introduced to characterize shale fracture surface morphology with the aim to provide a foundation for the development of shale resources. Three shale samples were fractured by the Brazilian test, and the height distribution of the fracture surface was captured by a three-dimensional profilometer. Then, three-dimensional fracture surface morphology was regarded as a set of two-dimensional profiles, which converted three-dimensional information into two-dimensional data. Roughness, joint roughness coefficient, fractal dimension, tortuosity, and dip angle were employed to characterize shale fracture surface morphology, and their calculation methods were also, respectively, proposed. It was found that roughness, joint roughness coefficient, fractal dimension, tortuosity, and dip angle were all directional, and they varied greatly along with different directions. Roughness, joint roughness coefficient, fractal dimension, tortuosity, absolute dip angle, and overall trend dip angle were among 0.0834–0.2427 mm, 2.5715–10.9368, 2.1000–2.1364, 1.0732–1.1879, 17.7498°–24.5941°, and −3.7223°–13.3042°, respectively. Joint roughness coefficient, fractal dimension, tortuosity, and dip angle were all positively correlated with roughness.

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Geometrical description and permeability calculation about shale tensile micro-fractures

Cited by 21 publications

References 21 publications

Investigation on Two M_w 3.6 and M_w 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta

Investigation on Two M_w 3.6 and M_w 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta

Mechanical Property Measurements and Fracture Propagation Analysis of Longmaxi Shale by Micro-CT Uniaxial Compression

Characteristics Description of Shale Fracture Surface Morphology: A Case Study of Shale Samples from Barnett Shale

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Geometrical description and permeability calculation about shale tensile micro-fractures

Cited by 21 publications

References 21 publications

Investigation on Two Mw 3.6 and Mw 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta

Investigation on Two Mw 3.6 and Mw 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta

Mechanical Property Measurements and Fracture Propagation Analysis of Longmaxi Shale by Micro-CT Uniaxial Compression

Characteristics Description of Shale Fracture Surface Morphology: A Case Study of Shale Samples from Barnett Shale

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Investigation on Two M_w 3.6 and M_w 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta

Investigation on Two M_w 3.6 and M_w 4.1 Earthquakes Triggered by Poroelastic Effects of Hydraulic Fracturing Operations Near Crooked Lake, Alberta