Experimental study on the influence of gas pressure on CH4 adsorption-desorption-seepage and deformation characteristics of coal in the whole process under triaxial stress

Lin, Haiqing; Ji, Pengfei; Kong, Xiangguo; Li, Shugang; Xiao, Tao; Li, Bai

doi:10.1016/j.fuel.2022.126513

Cited by 26 publications

(8 citation statements)

References 34 publications

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“…Based on the adsorbed gas quantities at different equilibrium gas pressures, the Langmuir equation 46 was regressed to calculate the gas adsorption constants for the experimental coal sample. The calculated values are as follows: the “ a ” value is 23.549 m 3 /t, and the “ b ” value is 0.588 MPa –1 .…”

Section: Model Validationmentioning

confidence: 99%

“…Coal is a dual medium of pore fracture, and the deformation of coal and the flow of CBM during the mining process are under the fluid–solid coupling effect. Coal and gas outburst is also a disaster phenomenon caused by the instability and failure of coal under the fluid–solid coupling effect. , Therefore, if the migration law of the CBM in coalbeds is to be more in line with reality, the fluid–solid coupling problem of the CBM in coalbeds must be considered. Zou studied the fluid–solid coupling characteristics of methane-containing coal in the hydraulic fracturing (HF) process and obtained the five-stage change characteristics of gas pressure response, strain change, and gas diffusion parameters and provided theoretical support and practical guidance for field test parameter selection to enhance the CBM recovery mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Fluid–Solid Coupling Characteristics of Methane-Containing Coal during Borehole Extraction of Coalbed: Numerical Modeling and Experimental Research

Yan,

Wen,

Jin

et al. 2023

ACS Omega

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The control and utilization of coalbed methane (CBM) are crucial for ensuring the safety of coal mining operations and mitigating greenhouse gas emissions. Predrainage of CBM from boreholes plays a pivotal role in preventing CBM accidents, harnessing CBM energy resources, and reducing greenhouse gas emissions. To better understand the evolution of key parameters during the predrainage process of CBM boreholes, this study, based on fundamental assumptions of coupling models, integrates the theories of elasticity, seepage mechanics, and fluid mechanics. It establishes a comprehensive mathematical model that reveals the interrelationships among the stress field, deformation field, and seepage field within methane-containing coal systems. By comparing numerical solutions with analytical solutions and conducting physical similarity simulation experiments, the study demonstrates the correctness of the methane-containing coal fluid–solid coupling model. The model developed in this study represents an improvement over traditional methane-containing coal seepage theories and fluid–solid coupling model theories and can be widely applied in the prevention of coal and CBM outbursts as well as CBM extraction.

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Section: Model Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fluid–Solid Coupling Characteristics of Methane-Containing Coal during Borehole Extraction of Coalbed: Numerical Modeling and Experimental Research

Yan,

Wen,

Jin

et al. 2023

ACS Omega

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“…During mining, disasters such as gas, sudden water, ground pressure, and dust pose serious threats to workers' lives and health [1][2][3][4][5], and with the mining of shallow coal resources, coal resources must be worked at greater depths [6]. Under deep mining conditions, the coal seam itself, the stress distribution thereon, and the gas assignment characteristics tend to be complicated, and the form of the coal seam group assignment becomes more common [7].…”

Section: Introductionmentioning

confidence: 99%

The Physical Behavior of Protected Coal Seams Based on Triaxial Unloading Conditions

Chen,

Xue,

Guo

et al. 2024

Sustainability

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Protective seam mining is the most economical and effective measure for eliminating coal and gas herniation. To study the unloading effect of the mining of a protective seam on the protected layer, and to better grasp the effect of the protective layer on the abatement, conventional triaxial tests were conducted on coal samples with the unloading of the axial pressure and the peripheral pressure. The results showed that, under the unloading path, the bias stress–axial strain curve showed a sudden upward trend upon unloading, and the slope of the curve increased suddenly, which was more obvious after the peripheral pressure exceeded 10 MPa; stress unloading before the peak accelerated the yielding of the specimen. Under the unloading test path, the deformation modulus of the coal samples decreased with the decrease in the perimeter pressure, while the damage factor and Poisson’s ratio increased with the decrease in the perimeter pressure. Compared to the conventional triaxial test, under the unloading condition, the cohesion of the coal samples at peak stress decreased by 93.41% and the angle of internal friction increased by 37.41%, while the cohesion at the moment of residual strength decreased by 89.60% and the angle of internal friction increased by 37.44°. The brittleness index of the coal samples under unloading conditions with a peripheral pressure of 5 MPa, 10 MPa, 15 MPa, and 20 MPa increased by 178.83%, 159.18%, 87.93%, and 63.89%, respectively, compared to the conventional triaxial test. It can be seen that the greater the enclosing pressure, the smaller the difference in the brittleness index of the coal body.

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“…In the study of coal pore structure, fractal dimension can represent the complexity or roughness of coal pore structure, so as to effectively represent pore characteristics. There are many calculation methods for fractal dimension, includes Menger (Fu et al, 2005;Zhao et al, 2023), Frenkel-Halsey-Hill (Yao et al, 2008;Huang L. K. et al, 2023;Huang L. et al, 2023), BET (Dormant and Adamson, 1972;Lin et al, 2023) and Langmuir (Rigby, 2005;Ji et al, 2023) fractal models, etc. Previous research results play a positive role in understanding pore structure characteristics of disturbed coal and studying the gas adsorption characteristics thereof; however, due to the complexity of disturbed coal, research into the influences of pore structures in disturbed coal on gas adsorption should be studied further.…”

Section: Introductionmentioning

confidence: 99%

Effect of disturbed coal pore structure on gas adsorption characteristics: mercury intrusion porosimetry

Liang,

Sun,

et al. 2024

Front. Energy Res.

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Studying pore structures of disturbed coal and their influences on adsorption characteristics is conducive to in-depth understanding of occurrence and migration of gas in reservoirs in areas prone to coal and gas outbursts. A mercury porosimeter and a high-pressure gas adsorption instrument were separately used to investigate pore structures and measure adsorption characteristics of disturbed coal and undisturbed coal in Ningtiaota Coal Mine and Xigu Coal Mine (Shaanxi Province, China). In addition, pore structures and gas adsorption characteristics of coal samples were studied. The Menger’s sponge model was adopted to calculate fractal dimensions of coal samples, to estimate influences of pore structures and fractal features on the gas adsorption characteristics of disturbed and undisturbed coal. Results show that the pore volume of undisturbed coal is mainly contributed by micropores and transitional pores, while that of disturbed coal arises mainly from macropores and mesopores. Micropores and transitional pores account for large proportions of the specific surface area of pores in both disturbed and undisturbed coal. The adsorption isotherms of disturbed and undisturbed coal conform to the Langmuir equation and tectonism increases the limiting adsorption quantity of coal. The fractal dimensions D1 of the four types of coal samples in the experiments are in the range of 2.7617–2.9961, while the fractal dimensions D1 and D2 of disturbed coal are both larger than those of undisturbed coal, indicating that disturbed coal is more likely to collapse under high pressure. The total pore volume, total specific surface area of pores, and fractal dimensions are positively correlated with the adsorption constant a, while they have U-shaped correlations with the adsorption constant b of coal samples. The adsorption constant a of disturbed coal is always greater than that of undisturbed coal, while no obvious trend is observed between the adsorption constant b and tectonism. The research results can provide theoretical basis for further study of gas occurrence in disturbed coal seams.

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Experimental study on the influence of gas pressure on CH4 adsorption-desorption-seepage and deformation characteristics of coal in the whole process under triaxial stress

Cited by 26 publications

References 34 publications

Fluid–Solid Coupling Characteristics of Methane-Containing Coal during Borehole Extraction of Coalbed: Numerical Modeling and Experimental Research

Fluid–Solid Coupling Characteristics of Methane-Containing Coal during Borehole Extraction of Coalbed: Numerical Modeling and Experimental Research

The Physical Behavior of Protected Coal Seams Based on Triaxial Unloading Conditions

Effect of disturbed coal pore structure on gas adsorption characteristics: mercury intrusion porosimetry

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