Study for the Effect of Temperature on Methane Desorption Based on Thermodynamics and Kinetics

Gao, Zheng; Ma, Dongmin; Chen, Yue; Zheng, Chao; Teng, Jinxiang

doi:10.1021/acsomega.0c05236

Cited by 24 publications

(15 citation statements)

References 36 publications

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“…Through low-temperature N 2 adsorption (LTAN) and lowpressure CO 2 adsorption (LPCA) experiments, Hu et al (2020) and found that super micropore structures smaller than 2 nm accounted for the majority of the total pore specific surface, while methane adsorption capacity increased with the increase of micropore PV and micropore SSA, concluding that super micropore structures smaller than 2 nm were the dominant factor affecting methane adsorption capacity. The production of CBM mainly goes through the processes of drainage depressurization-desorption-diffusion-seepage (Lin et al, 2016;Gao et al, 2020). Maximizing the desorption of gas adsorbed inside the pore space is the most important factor in achieving maximum capacity in CBM wells.…”

Section: Introductionmentioning

confidence: 99%

The Influence Mechanism of Pore Structure of Tectonically Deformed Coal on the Adsorption and Desorption Hysteresis

Ren

Weng

et al. 2022

Front. Earth Sci.

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Pore is the main adsorption and desorption space of coalbed methane (CBM). Pore size configuration and connectivity affect the adsorption/desorption hysteresis effect. Using tectonically deformed coal (TDC) and original structure coal of medium- and high-rank coal as the research objects, through the N2/CO2 adsorption experiment to analyze the pore size distribution and connectivity of different scales. We investigate the control mechanism of heterogeneous evolution in the key pore scales against adsorption/desorption hysteresis characteristics during coal metamorphism and deformation by combining the CH4 isothermal adsorption/desorption experiment under 30°C equilibrium moisture. The findings indicate that the super micropores (<2 nm) are mainly combination ink bottle-shaped pores and have worse connectivity as the degree of metamorphism and deformation increases. The super micropores occupy the vast majority of pore volume and specific surface area; its pore size distribution curve change presents an “M” bimodal type and is mainly concentrated in two pore segments of 0.45–0.70 nm and 0.70–0.90 nm. The effect of ductile deformation exerts a significantly greater effect on super micropores than brittle deformation. The exhibited adsorption–desorption characteristics are the result of the combined effect of the unique pore structure of the TDCs and different moisture contents. The presence of a large number of super micropores is the most important factor influencing the degree of gas desorption hysteresis. The “ink-bottle effect” is the primary cause of gas desorption hysteresis. For CBM development, some novel methods to increase desorption and diffusion rate at the super micropores scale should be considered.

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Section: Introductionmentioning

confidence: 99%

The Influence Mechanism of Pore Structure of Tectonically Deformed Coal on the Adsorption and Desorption Hysteresis

Ren

Weng

et al. 2022

Front. Earth Sci.

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“…The spatial distribution of gas content is firstly controlled by geological structure. Regional and mine structures form different sealing conditions, which have a considerable control effect on the distribution of gas content in coal seams (Moore 2012;Gao et al 2020;Quan et al 2020). Given a large compressive stress in compressional fault, fault gouge and mylonite with compacted structure are relatively developed, and the permeability of gas is poor (Bustin and Clarkson 1998;Zhang et al 2016;Tong et al 2019).…”

Section: Understanding Of Coal Seam Gas Occurrence Characteristicsmentioning

confidence: 99%

Prediction of gas pressure in thin coal seams in the Qinglong Coal Mine in Guizhou Province, China

Zhang

Wang

et al. 2021

J Petrol Explor Prod Technol

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Thin coal seams in mines usually lack gas data. Thus, preventing and controlling gas outbursts of thin coal seams are difficult. In this study, a coal structure index, which is used to express the damage degree of coal, was estimated by logging curve. In accordance with the contour line of the floor of the coal seam, structural curvature was calculated to express the complexity of the coal seam structure quantitatively. Subsequently, relationships among the burial depth, thickness, coal structure index, structural curvature were analyzed on the basis of the gas pressure of coal seam. The gas pressure values of the coal seams of Nos. 22, 24, and 27 in the study area were predicted by multiple linear regression (MLR) and were then verified and analyzed. The deviation rate of the MLR method was 6.5%–19.7%, with an average of 13.0%. The average deviation rate between the predicted value and the measured value was 11.6%, except for the measuring point of No. 2, which had a large deviation. Results show that the prediction accuracy of the aforementioned method is acceptable and has practical value in the prediction of gas pressure in thin coal seams without measured data. The results in the gas pressure prediction provide a basis for evaluating the risk of gas outbursts in thin coal seams.

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“…With an increase in the degree of metamorphism of coal, the diffusion coefficient of methane first decreases and then gradually increases. , Through analysis of the change laws of the Langmuir effective diffusion coefficient with the coal rank and their influencing factors, Yan found that a rise in the coal rank increased the development degree of micropores and gas desorption capacity. Wang, Gao, and Lin concluded a higher adsorption pressure of coal mass is related to the stronger movement of methane molecules, more favorable for gas desorption, and accelerates gas diffusion. Additionally, the high pressure increases the diffusion coefficient and the cumulative amount of gas desorption and diffusion.…”

Section: Introductionmentioning

confidence: 99%

Desorption Effects and Laws of Multiscale Gas-Bearing Coal with Different Degrees of Metamorphism

et al. 2021

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Understanding gas desorption effects and laws of coal mass under different conditions is essential for the effective exploration of gas emission in underground coal mines, prediction and prevention of coal and gas outburst, accurate detection of gas [coal methane (CBM)] content in coal seams, and prediction of CBM productivity. Using a self-developed test platform, we simulated gas adsorption and desorption and performed physical simulation tests. Based on these tests, we investigated the differences in the total amount of gas desorbed, desorption rate, and initial amount of gas desorbed by long-flame coal, coking coal, meager-lean coal, and anthracite on different scales under different gas pressures. Two methods are used for compensating gas loss, namely, the method and the power function method, as stipulated in the current Standards for Determination of Gas Content in Coal Seams in China. By combining these two methods, we analyzed the applicability of these two compensation methods in coal on different scales with varying degrees of metamorphism under gas pressures. The results demonstrated that (1) under the same gas adsorption pressure, the cumulative total amount of gas desorbed per unit mass within 90 min for the four kinds of coal samples increases with the degree of metamorphism. Changes in the cumulative amount of gas desorbed per unit mass and the desorption rate with the degree of metamorphism vary with stages. Notably, a higher adsorption pressure leads to a more obvious stage change. (2) Under the same gas adsorption pressure, the cumulative total amount of gas desorbed per unit mass and the desorption rate of coal with the same degree of metamorphism are inversely proportional to the size of the coal sample. This indicates significant scale effects. The larger the degree of metamorphism and gas adsorption pressure, the more significant are the scale effects of gas desorption. (3) For coal with the same degree of metamorphism, the higher gas adsorption pressure leads to a larger cumulative total amount of gas desorbed and a higher desorption rate throughout the desorption process and a larger proportion of the cumulative amount of gas desorbed in the initial stage. The smaller the size of the coal sample, the more obvious the pressure effects of gas desorption are. (4) For coal samples with the same degree of metamorphism, when the gas content in coal seams is kept constant, the larger the size of the coal sample, the smaller the actual gas loss is. Moreover, a higher gas content in coal seams results in a greater gas loss and a larger calculation error for gas loss. Compared with the method, the power function method reveals a smaller deviation between the calculated gas loss and the actual gas loss, which is found to be more accurate. A larger size coal sample results in higher accuracy in the calculated gas loss.

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Study for the Effect of Temperature on Methane Desorption Based on Thermodynamics and Kinetics

Cited by 24 publications

References 36 publications

The Influence Mechanism of Pore Structure of Tectonically Deformed Coal on the Adsorption and Desorption Hysteresis

The Influence Mechanism of Pore Structure of Tectonically Deformed Coal on the Adsorption and Desorption Hysteresis

Prediction of gas pressure in thin coal seams in the Qinglong Coal Mine in Guizhou Province, China

Desorption Effects and Laws of Multiscale Gas-Bearing Coal with Different Degrees of Metamorphism

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