Observations of Fractures Induced by Hydraulic Fracturing in Anisotropic Granite

Chen, Youqing; Nagaya, Y.; Ishida, Tsuyoshi

doi:10.1007/s00603-015-0727-9

Cited by 172 publications

(74 citation statements)

References 15 publications

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“…Hydraulic fracturing behavior of different granites has been reported by Haimson (1975Haimson ( , 1999, Haimson and Lee (1980), Solberg et al (1980), Haimson and Doe (1983), Haimson and Zhao (1991), Zhao et al (1996), Ishida et al (1997Ishida et al ( , 2000Ishida et al ( , 2004Ishida et al ( , 2012 and Chen et al (2015). However, in these studies granites were mainly treated as low-permeability rocks and the influence of infiltration of injection fluid has rarely been discussed.…”

Section: Introductionmentioning

confidence: 98%

“…Moreover, there is anisotropy phenomenon in some granites and they have three cleavages or planes of weakness called rift, grain and hardway (Douglass and Voight 1969;Fujii et al 2007). The cleavages have different tensile strength and permeability and therefore influence fracture generation in laboratory hydraulic fracturing test (Chen et al 2015;Zhuang et al 2016a;Diaz et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Effect of Water Infiltration, Injection Rate and Anisotropy on Hydraulic Fracturing Behavior of Granite

et al. 2018

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Hydraulic fracturing tests on Pocheon granite cylinders at seven different injection rates varying from 1 to 100 mm 3 /s were conducted. They were compared with sleeve fracturing tests in which borehole was sleeved, and therefore, water infiltration influence was excluded. Hydraulic fracturing behavior of granite is significantly influenced by water infiltration, which is closely related to the preexisting microcracks in granite as well as the cleavage anisotropy. There was a threshold injection rate to fracture the granite specimen under given stress conditions. When the injection rate is below the threshold, water infiltrated granite matrix with slow increment of injection pressure, and the specimen finally reached a full saturation without fracturing. Injection pressure developed nonlinearly with time during water infiltration, while approximately linearly when infiltration was excluded. For both hydraulic and sleeve fracturing tests, breakdown pressure increases with increasing injection rate. The breakdown pressures by sleeve fracturing were more than two times higher than those in hydraulic fracturing. X-ray computed tomography (CT) observations show that induced fractures are along the weaker cleavage parallel to the direction of the vertical stress. The higher breakdown pressure results in a larger aperture of fractures in hydraulic fracturing tests.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Effect of Water Infiltration, Injection Rate and Anisotropy on Hydraulic Fracturing Behavior of Granite

et al. 2018

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“…With the increase of fluid viscosity (such as the case of a gel), the branches disappear and hydraulic fracture turns into a simple wing shape. We note that in these studies, only Ishida et al [10][11][12][13] used the supercritical CO 2 and liquid CO 2 as fracturing fluid of which the viscosity is smaller than 1 mPa¨s. Supercritical CO 2 is important but difficult to use in hydraulic fracturing [16], thus, we need to perform systematic studies to enhance the theoretical basis for unconventional resource production.…”

Section: Introductionmentioning

confidence: 99%

“…Some researchers [7][8][9] have investigated the influence of injection rate on hydraulic fractures through laboratory experiments, which indicated that under the same experimental conditions, with the increase of injection rate, the branches of the hydraulic fracture would decrease, and the complex fracture network turns into a single straight fracture. Ishida et al [10][11][12][13], Fan and Zhang [9], and Hou et al [14], have performed laboratory experiments on the effect of fluid viscosity. Warpinski et al [15] have analyzed the microseismic monitoring data in hydraulic fracturing sites.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Influence of In-Situ Stress Ratio, Injection Rate and Fluid Viscosity on Hydraulic Fracture Propagation Using a Distinct Element Approach

Zhang

et al. 2016

Energies

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Numerical simulation is very useful for understanding the hydraulic fracturing mechanism. In this paper, we simulate the hydraulic fracturing using the distinct element approach, to investigate the effect of some critical parameters on hydraulic fracturing characteristics. The breakdown pressure obtained by the distinct element approach is consistent with the analytical solution. This indicates that the distinct element approach is feasible on modeling the hydraulic fracturing. We independently examine the influence of in-situ stress ratio, injection rate and fluid viscosity on hydraulic fracturing. We further emphasize the relationship between these three factors and their contributions to the hydraulic fracturing. With the increase of stress ratio, the fracture aperture increases almost linearly; with the increase of injection rate and fluid viscosity, the fracture aperture and breakdown pressure increase obviously. A low value of product of injection rate and fluid viscosity (i.e., Qµ) will lead to narrow fracture aperture, low breakdown pressure, and complex or dispersional hydraulic fractures. A high value of Qµ would lead wide fracture aperture, high breakdown pressure, and simple hydraulic fractures (e.g., straight or wing shape). With low viscosity fluid, the hydraulic fracture geometry is not sensitive to stress ratio, and thus becomes a complex fracture network.

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“…The fluorescent method is one of the techniques to observe and quantify micro-cracks within a specimen by image analysis after injecting fluorescent paint to micro-cracks. Wajima et al (2000) and Chen et al (2015) visualized microscopic pore spaces and micro-cracks filled with synthetic resin mixed with fluorescent paint under ultraviolet light for oil, gas, and geothermal reservoir rocks. However, since a specimen is cut or a thin section is made from the specimen, the results of the method are described in two dimensions.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Micro-damage of Concrete Specimens under Cyclic Uniaxial Loading by X-ray CT Method

Tanikura

Jung

Shintani

et al. 2016

ACT

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The X-ray CT method was applied to evaluate micro-damage -namely, deterioration of concrete specimens under cyclic uniaxial loading tests. The μ-focus X-ray CT scanner was used. Concrete cylinders with a diameter of 50 mm and a length of 100 mm were prepared as specimens. Cyclic uniaxial loading tests were conducted on the specimens. The X-ray CT images of the specimens were taken at the loading level 0, 60, 70, 80 and 90 percent of their uniaxial compressive strength. For three dimensional CT images of the specimen, the Three Dimensional Medial Axis Analysis (3DMA) method was applied to evaluate porosity and width, length, persistence of cracks which represent deterioration of the specimen. As the results, slight micro-fracturing occurs until a loading level R = 60%, and starts to increase at R of 60% to 70%. The cracking occurs in a part of the mortar near boundary between aggregate and mortar, and the crack links to another crack with increasing loading level. The degree of cracking varies according to the position dependent on the final apparent fracture surface of the specimen. It is concluded that the X-ray CT method with 3DMA is effective for not only evaluating the state of micro-cracking within the specimen, but also estimating the process of deterioration of the specimen with an increasing loading level.

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Observations of Fractures Induced by Hydraulic Fracturing in Anisotropic Granite

Cited by 172 publications

References 15 publications

Effect of Water Infiltration, Injection Rate and Anisotropy on Hydraulic Fracturing Behavior of Granite

Effect of Water Infiltration, Injection Rate and Anisotropy on Hydraulic Fracturing Behavior of Granite

Numerical Investigation of Influence of In-Situ Stress Ratio, Injection Rate and Fluid Viscosity on Hydraulic Fracture Propagation Using a Distinct Element Approach

Evaluation of Micro-damage of Concrete Specimens under Cyclic Uniaxial Loading by X-ray CT Method

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