Experimental Study on the Thermal Effect during Gas Adsorption and Desorption on the Coal Surface

Hao, Jianfeng; Li, Bing; Sun, Weiji

doi:10.1021/acsomega.0c05505

Cited by 16 publications

(10 citation statements)

References 35 publications

(42 reference statements)

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“…Durucan et al proposed that the matrix swelling caused by CO 2 injection has a serious effect on the permeability of coal by carrying out the deformation test of CO 2 adsorption on coal samples and found that the swelling of coal increases with the increase of the coal rank, which is considered to be related to the larger adsorption capacity of high rank coal. The temperature of coal increases in the process of gas adsorption and decreases when desorption. , This change is more obvious especially in the case of coal and gas outburst . When the temperature of the coal seam rises, the adsorption capacity of CBM changes. , Killingley and co-workers showed that the methane adsorption capacity decreased by 0.12 cm 3 /g when the temperature increased by 1 °C at 5 MPa.…”

Section: Introductionmentioning

confidence: 99%

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Principle and Application for Thermal Exploitation of Coalbed Methane Recovery

Wang,

Feng,

Zhou

et al. 2023

Energy Fuels

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Coalbed methane (CBM) is strongly adsorbed to coal, with over 95% existing in an adsorbed state, making it difficult to effectively extract using traditional borehole drainage or drainage gas methods, particularly in low permeability and under pressure CBM reservoirs. This study proposes thermal-enhanced CBM extraction by superheated water injection. Laboratory experiments were first conducted to examine deformation and temperature change during coal adsorption/desorption, to quantify adsorption heat at low (room temperature−150 °C) and high (150−240 °C) temperature ranges, and to elucidate the potential physical mechanisms of temperature modulation on coal adsorption of methane. Further experiments studied two-phase methane−water flow under elevated temperature and thermal-induced methane drainage affected by the water lock effect. Pilot field tests then validated the feasibility and effectiveness of this thermal extraction technology based on the theoretical findings. The results demonstrate that (1) energy conversion occurs during coal adsorption/desorption of methane, absorbing heat and causing matrix shrinkage during desorption. (2) Heterogeneous coal adsorption potential requires increased temperature to desorb methane from deep wells into the free state. Under isobaric conditions, adsorption heat is significantly higher at 150−240 °C versus room temperature−150 °C due to potential well depth effects. (3) The gas-driving-water process involves liquid flow, gas−liquid twophase flow, and gas flow stages. Elevated temperature facilitates water and gas flows, accelerates gas breakthrough, and improves the production rate. (4) High temperature eliminates the water lock effect and increases the desorption rate to around 80% regardless of adsorption pressure, greatly shortening equilibrium time. (5) Further field tests show that the drainage period after thermal injection is only 1/46−1/31 that of the conventional method given the same production volume. Thus, thermal-enhanced CBM extraction is disruptive, with this study providing theoretical and engineering basis.

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Section: Introductionmentioning

confidence: 99%

“…The temperature of coal increases in the process of gas adsorption and decreases when desorption. 14,15 This change is more obvious especially in the case of coal and gas outburst. 16 When the temperature of the coal seam rises, the adsorption capacity of CBM changes.…”

Section: Introductionmentioning

confidence: 99%

Principle and Application for Thermal Exploitation of Coalbed Methane Recovery

Wang,

Feng,

Zhou

et al. 2023

Energy Fuels

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“…Yi et al 9 proposed a concentration-based extraction pressure adjustment method to improve the gas utilization rate. Chen et al 10 and Hao et al 11 established a gas–solid coupling model to study the gas extraction law of the three-dimensional model of a coal seam. Liu et al 12 proposed a theoretical model to describe gas desorption, diffusion, and flow around a drainage hole based on field experimental data.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Space–Time Synergy of Coal and Gas Co-mining

et al. 2022

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The co-mining of coal and gas is the inevitable future direction of the mining of coal resources. Taking coal mining and gas extraction as the two subsystems of the coal and gas co-mining system, to reveal the mechanism of action between coal mining and gas extraction is the premise of orderly co-mining. On the basis of a similar simulation experiment of coal and gas co-mining, by obtaining the gas migration law during the mining process and collecting a large amount of data on the coal production and gas extraction, it is found that the two subsystems of coal extraction and gas extraction in the coal and gas co-mining system promote and restrict each other. The control parameters for coal mining and gas extraction that affect co-mining are identified. To coordinate the process connection between coal mining and gas extraction, the optimal synergistic relationship of co-mining should be found. The recovery rate and economic benefit of coal and gas resources are taken as the optimization objective function of coal and gas co-mining. Taking the safety production laws, regulations, and production technology-level restrictions of coal mining and gas drainage as constraints, by constituting a nonlinear model for the collaborative optimization of coal and gas co-mining, the method of determining the optimal advancing speed and optimal gas drainage volume of the working face is proposed. By optimizing variables, such as coal mining advancement, coal mining time, gas extraction time, and gas extraction volume, the co-mining of coal and gas is ensured to be safe and efficient, and the output of coal and gas resources is optimized. The time connection and the process succession of the two subsystems are attained. An overall orderly structure is formed between the coal mining system and the gas extraction system, and the mechanism of the cooperative co-mining of coal and gas is revealed. This research has important significance with regard to improving the basic theoretical system of coal and gas co-mining. The control variables of the co-mining working face in the Shaqu mine are optimized. After optimization, the profit is increased by 16.3%, and the gas extraction rate is increased by 2.6%. The drilling spacing is optimized according to the optimization results. The simulation shows that 7 m is the optimal drilling spacing of the working face.

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“…The gas drainage technology and gas migration law complement each other. 5 − 12 Thick and high-gas coal seams are widespread in the United States, Australia, and China. 13 − 16 However, there are a few pieces of research on the gas extraction technology for slice mining of extra-thick coal seams that need to be carried out.…”

Section: Introductionmentioning

confidence: 99%

“…Gas prevention is an important guarantee for safe and efficient production in mines, and as the mining depth increases, coal mining will face more and more gas prevention problems in the future. − At present, various technologies have been developed for gas extraction, such as coal seam preextraction, pressure relief gas drainage in the adjacent layer, bottom drainage roadway extraction, high alley pumping extraction, high level borehole extraction, goaf buried pipe extraction, large diameter drilling extraction, and so forth. The gas drainage technology and gas migration law complement each other. − Thick and high-gas coal seams are widespread in the United States, Australia, and China. − However, there are a few pieces of research on the gas extraction technology for slice mining of extra-thick coal seams that need to be carried out.…”

Section: Introductionmentioning

confidence: 99%

Research on Gas Extraction and Cut Flow Technology for Lower Slice Pressure Relief Gas under Slice Mining of Extra-thick Coal Seam

Shi

Hao

et al. 2022

ACS Omega

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For extra-thick coal seams, slice mining is a safer mining method than top coal mining, which can effectively reduce the strong mine pressure behavior caused by mining. However, in the slice mining of high-gas and extra-thick coal seams, the gas in the lower slice flows into the goaf, which increases the gas control difficulty on the upper slice working face. It is easy to cause the gas transfinite at the upper corner in the upper slice and reduce the mining efficiency. Therefore, it is of a great significance to carry out the research on gas control technology in slice mining of the extra-thick coal seam. There are some problems in the gas control of slice mining, such as a single gas control method, low control efficiency, and unclear gas migration law. Therefore, it is necessary to study the gas migration law and propose a targeted prevention and control the technical scheme. In order to improve the gas control efficiency of the extra-thick coal seam, the evolution law of permeability of the lower slice is obtained under mining through experimental research. The liquid–solid coupling seepage-flow model for gas migration is established in the lower slice. Comsol Multiphysics software is used to study the migration law of pressure relief gas in the lower slice. Based on the gas migration law, the gas extraction and cut flow technology for the lower slice long borehole is proposed. Through this technology, the amount of gas flowing into the upper slice goaf and the gas content of the lower slice are reduced, and the drilling horizon is optimized. The research results show that the determination of the optimal drilling horizon of the lower slice needs to balance the amount of gas flowing into the goaf and the total amount of gas extraction. The range of 3–7 m horizon in the lower slice is appropriate to the boreholes arranged. When the borehole is located in the lower slice −3 m horizon, the 360 day gas emission quantity of goaf can be reduced to 51.2% of the nondrilled emission quantity, and the total extraction amount is 1143 m 3 . When the borehole is located in the lower slice −7 m horizon, the 360 day gas emission quantity of goaf can be reduced to 95.31% of the nondrilled emission quantity, and the total extraction amount is 1461 m 3 . Considering the gas emission capacity of the upper slice and ensuring that the total extraction volume of the lower slice is maximized and the boreholes in the lower slice are not damaged, the boreholes are located in the −6 m horizon of the lower slice.

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Experimental Study on the Thermal Effect during Gas Adsorption and Desorption on the Coal Surface

Cited by 16 publications

References 35 publications

Principle and Application for Thermal Exploitation of Coalbed Methane Recovery

Principle and Application for Thermal Exploitation of Coalbed Methane Recovery

Analysis of the Space–Time Synergy of Coal and Gas Co-mining

Research on Gas Extraction and Cut Flow Technology for Lower Slice Pressure Relief Gas under Slice Mining of Extra-thick Coal Seam

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