Investigation on the damage of high-temperature shale subjected to liquid nitrogen cooling

Wu, Xiaoguang; Huang, Zhongwei; Ran, Li; Zhang, Shikun; Wen, Haitao; Huang, Pengpeng; Dai, Xianwei; Zhang, Chengcheng

doi:10.1016/j.jngse.2018.07.005

Cited by 108 publications

(28 citation statements)

References 32 publications

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“…However, the absolute content of micropores of QS-800 decreases than OS-800, while the absolute content of ne pores, mesopores, macropores, and the total porosity increase obviously. This is because LN 2 rapid cooling caused signi cant damage to the high-temperature rock samples than the air cooling (Wu et al 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Rapid cooling of LN 2 creates a large thermal gradient in the rock and produces a very high thermal stress in a short period of time. This thermal stress can generate a large number of microcracks in the rock and promote the expansion of the original cracks, which may reduce the mechanical properties of the rock (Wu et al 2018). Therefore, it is of great signi cance to study the effects of high-temperature heating and LN 2 cooling on the properties of red sandstone and to reveal the feasibility and prospect of geothermal LN 2 fracturing technology.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study on the Compressive Strength and AE Characteristics of High-temperature Treated and LN2 Cooled Sandstone

Ding

Sun

Jia

et al. 2021

Preprint

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Liquid nitrogen (LN2) fracturing is beneficial to the development and utilization of geothermal energy. In this paper, the red sandstone was heated from room temperature to different temperatures (25°C-800°C) and then cooled with LN2. After attaining the room temperature, NMR, uniaxial compression, and acoustic emission (AE) tests were conducted, and results were compared for different samples. The results showed that with the increase in quenching temperature difference, the volume of micropores decreased gradually, while the volume of fine pores, mesopores, macropores and total porosity increased, resulting in the reduction of the compressive strength. Higher quenching temperature difference also reduced the sample’s total time to fail, and the failure mode was transformed from single inclined shear failure to conical failure. This is because the thermal stress (caused by the rapid cooling of LN2) expanded the original cracks of the sandstone, leading to high porosity and low compressive strength of the heat-treated and quenched samples.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Compressive Strength and AE Characteristics of High-temperature Treated and LN2 Cooled Sandstone

Ding

Sun

Jia

et al. 2021

Preprint

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“…From the above, there are few studies on permeability enhancement and thermal damage in coal and rock induced by heating-cooling treatment. Wu et al [51,52] used shale and granite specimens to study the variation of physico-mechanical properties under heating-cooling treatment. Their results demonstrated that the permeability of heated specimens significantly increased after LN 2 -cooling treatments, while the density, P-wave velocity, strength and elastic modulus decreased.…”

Section: Introductionmentioning

confidence: 99%

Microcrack evolution and permeability enhancement due to thermal shocks in coal

Zhang

Wang

et al. 2020

PLoS ONE

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To understand the effects of thermal shock on microcrack propagation and permeability in coal, thermal shock tests were conducted on coal specimens by using a constant temperature drying oven (105˚C) and a SLX program controlled cryogenic tank. The growth and propagation of microcracks were measured with computer tomography (CT) scanning and scanning electron microscope (SEM) tests. Results showed that thermal shocks improved the permeability of coal significantly. Notably, the permeability of coal after thermal shocks increased from 211.31% to 368.99% and was positively correlated with temperature difference. CT scanning images revealed that thermal shocks increased the crack number, crack volume and crack width as well as smoothened and widened the gas flow paths, thereby enhancing coal permeability. Moreover, SEM images showed that heating-cooling shocks created more new microcracks, forming more complex crack propagation paths and better connectivity among microcracks in coal compared to cooling shocks. We proposed a crack propagation criterion for coal to explain the mechanism of crack failure and propagation during thermal shocks. Our experiment results and theoretical analysis indicate that the heating-cooling shock is more effective in damaging and breaking coal than the cooling shock. Thus, it can be used as an alternative approach to enhance coal permeability in the production of coalbed methane (CBM).

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“…Quite a few researches on cryogenic fracturing [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] have been carried out by scholars and engineers, in which significant efforts are devoted to investigating the feasibility of cryogenic fracturing for engineering application and figuring out the damage mechanism of cryogenic fracturing. These works are largely comprised of experimental studies in the laboratory.…”

Section: Introductionmentioning

confidence: 99%

A Novel 2D Model for Freezing Phase Change Simulation during Cryogenic Fracturing Considering Nucleation Characteristics

Huang

Wang

2020

Applied Sciences

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A 2D computational fluid dynamics (CFD) model in consideration of nucleation characteristics (homogeneous/heterogeneous nucleation) using the volume of fluid (VOF) method and Lee model was proposed. The model was used to predict the process of a multiphase flow accompanied by freezing phase change during cryogenic fracturing. In this model, nucleation characteristic (homogeneous and heterogeneous nucleation) during the freezing process and the influence of the formed ice phase on the flowing behavior was considered. Validation of the model was done by comparing its simulation results to Neumann solutions for classical Stefan problem. The comparison results show that the numerical results are well consistent with the theoretical solution. The maximum relative differences are less than 7%. The process of multiphase flow accompanied by the freezing of water was then simulated with the proposed model. Furthermore, the transient formation and growth of ice as well as the evolution of temperature distribution in the computational domain was studied. Results show that the proposed method can better consider the difference between homogeneous nucleation in the fluid domain and heterogeneous nucleation on the wall boundary. Finally, the main influence factors such as the flow velocity and initial distribution of ice phase on the fracturing process were discussed. It indicates that the method enable to simulate the growth of ice on the wall and its effect on the flow of multiphase fluid.

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Investigation on the damage of high-temperature shale subjected to liquid nitrogen cooling

Cited by 108 publications

References 32 publications

Experimental Study on the Compressive Strength and AE Characteristics of High-temperature Treated and LN2 Cooled Sandstone

Experimental Study on the Compressive Strength and AE Characteristics of High-temperature Treated and LN2 Cooled Sandstone

Microcrack evolution and permeability enhancement due to thermal shocks in coal

A Novel 2D Model for Freezing Phase Change Simulation during Cryogenic Fracturing Considering Nucleation Characteristics

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