Failure characteristics of shale after being subjected to high temperatures under uniaxial compression

Huang, Linqi; Guo, Yuanxiong; Li, Xibing

doi:10.1007/s10064-021-02492-z

Cited by 26 publications

(3 citation statements)

References 45 publications

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“…29 The AE characteristics of shale can be understood by describing the time-and frequency-domain characteristics of the AE waveform. 30 Previous studies have shown that the AE characteristics of shale are affected by shale properties including pre-existing fracture, 27 fracture geometry, 31 pore structure, 26 mineral composition, water condition, 28 bedding, 32 anisotropy, 33 and external experimental environments (such as temperature, 34 axial stress, 27 confining pressure, 28 and other factors). 35 Fractal theory is an effective approach for investigating the complexity of rock mass fractures based on self-similarity and scale invariance characteristics.…”

Section: Introductionmentioning

confidence: 99%

Multifractal Analysis for the Acoustic Emission Energy Dissipation of Shale after Long-Term Immersion in Fracturing Fluids with Various pH

Xie,

Tan,

Lyu

et al. 2023

Energy Fuels

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The interaction between shale and fracturing fluids will change the internal pore structure and adsorption capacity of shale, which have an important impact on shale gas productivity. This study aims to investigate the variations in acoustic emission (AE) energy and multifractal characteristics of shale under different pH values of fracturing fluids with implications for shale gas productivity. A series of immersion experiments were carried out on shale with fracturing fluids, with pH values of 6, 7, and 8, respectively. The uniaxial compression tests and AE tests were conducted on shale under fracturing fluid immersion with pH values of 6, 7, and 8. The multifractal theory is applied to analyze the evolution of fracture closure and propagation during uniaxial compression based on AE signals. The study also examines the deformation and crack evolution of shale after long-term fracturing fluid immersion, with particular emphasis on fluid−rock reactions. The results show that the maximum cumulative AE energy of shale after immersion is higher than that of intact shale. The focus is on understanding the fracture evolution process of shale during uniaxial compression at different stages. The fluid−rock reactions determine the deformation and crack evolution of shale after longterm fracturing fluid immersion. The increase of shale spectrum width Δα after immersion indicates that the distribution of AE signals is more uneven after immersion. The Δf value of shale after acid fracturing fluid soaking changes more significantly than those of neutral or alkaline fracturing fluids. All the fractal spectra of shale samples generally show a left-skewed distribution. The values of spectrum parameters are affected by soaking fluid, soaking time, and compression stages, resulting in the variation of multifractal characteristics. Hydration expansion of clay minerals is dominant in the middle and late period of immersion. The research results have a certain guidance for understanding the deformation and crack evolution and the influence of rock−fluid reactions on the failure process of shale samples.

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Section: Introductionmentioning

confidence: 99%

Multifractal Analysis for the Acoustic Emission Energy Dissipation of Shale after Long-Term Immersion in Fracturing Fluids with Various pH

Xie,

Tan,

Lyu

et al. 2023

Energy Fuels

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“…The depth of the Mponeng mine in South Africa, the deepest mine in the world, has surpassed 4000 m [ 5 ] and as a result of the development of mineral resources in China, mines in the country will reach an underground depth of 1000–2000 m [ 6 , 7 ]. Deep rock mass occurs in a complex environment consisting of a high-stress field, high-temperature field, high permeability–pressure field, fast unloading, and dynamic disturbance caused by hard-rock mining, resulting in frequent disasters [ 8 , 9 , 10 , 11 , 12 ], as shown in Figure 1 . For example, deep mining of the Kaiyang phosphate mine has led to a wide range of loose circles in the rock surrounding the underground engineering owing to the action of high stress; this simultaneously results in decreased rock strength, increased unstable block, and groundwater seepage, which has caused great engineering geological disasters [ 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Wave Dissipation and Energy-Absorption Characteristics of Wave-Absorbing Metal Plates with Different Aperture Sizes and Thicknesses under True-Triaxial Static-Dynamic-Coupling Loading

Huang

Zeng

et al. 2022

Materials

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Deep rock masses exist in a complex environment with multi−field coupling; therefore, it is necessary to develop a true−triaxial static−dynamic−coupling loading test machine to explore their characteristics and mechanical response mechanism. To meet the test requirements of true−triaxial loading and strong disturbance, a wave−absorbing metal plate was selected as the boundary material between the granite and transmission end, and the modified SHPB was used to perform static−dynamic−coupling loading tests. In this study, two series of experiments on wave− absorbing metal plates were conducted, which were fixed aperture sizes with different thicknesses and fixed thicknesses with different aperture sizes. The static−dynamic−coupling loading tests on each aperture size and plate thickness were carried out under the condition of equal energy impact. The effects of the aperture size and plate thickness on the incident− and reflection−stress curves, reflectivity, energy consumption law, energy evolution, and other mechanical properties of the wave−absorbing metal plate materials were studied. The results show that the peak stress and reflectivity decrease with increasing aperture size and plate thickness, and the influence of the thickness is greater than that of the aperture size. The energy−absorption rate of the wave−absorbing metal plate increased with increasing thickness and aperture size and was maximized when the aperture size and thickness were 6–7 mm and 3–4 mm, respectively. The variation trend of the energy reflectance is opposite to that of the energy absorption and reaches a minimum when the aperture size is 6–7 mm and plate thickness is 3–4 mm. The energy transmittance of the wave−absorbing metal plate fluctuated in a stable range, but the variation range was less obvious compared to that of the energy−absorption rate.

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“…Temperature also plays a key role in determining the damage behavior of rock. In a notable study conducted by Huang et al [9], researchers have implemented uniaxial compression tests of shale specimens under a high-temperature environment. Their results indicate that shale specimens with perpendicular bedding planes are more fragile than horizontal bedding planes with increasing temperature.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on Stress Relaxation of Yunnan Sandstone

Zheng

2022

Lithosphere

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This study presents the results from five relaxation tests conducted under uniaxial compression at room temperature. Test specimens were from sandstone formations at a mine, in Yunnan, and exhibited brittle failure. The test apparatus was valid for conducting stress relaxation experiments on sandstones by theoretical model and deformation measurements. Multiple load levels were applied in steps to each specimen, with each displacement level maintained for 12 d or longer. As soon as axial stress was decreased, it stabilized at an almost constant value after 12–24 h. Three distinct relaxation phases were observed to exist at all displacement levels except the specimen 3 in all tests. Based on the LM-NLSF method, model parameters under different strain levels were obtained. Comparison of test curves with theoretical curves showed that the Burgers model, which considers damage, was suitable for describing the stress relaxation properties of sandstones and the obtained parameters had a certain practical value.

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Failure characteristics of shale after being subjected to high temperatures under uniaxial compression

Cited by 26 publications

References 45 publications

Multifractal Analysis for the Acoustic Emission Energy Dissipation of Shale after Long-Term Immersion in Fracturing Fluids with Various pH

Multifractal Analysis for the Acoustic Emission Energy Dissipation of Shale after Long-Term Immersion in Fracturing Fluids with Various pH

Wave Dissipation and Energy-Absorption Characteristics of Wave-Absorbing Metal Plates with Different Aperture Sizes and Thicknesses under True-Triaxial Static-Dynamic-Coupling Loading

An Experimental Study on Stress Relaxation of Yunnan Sandstone

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