Current Status and Effective Suggestions for Efficient Exploitation of Coalbed Methane in China: A Review

Lu, Yiyu; Zhang, H. D.; Zhou, Zhe; Ge, Zhaolong; Chen, C. J.; Hou, Yudong; Ye, M. L.

doi:10.1021/acs.energyfuels.1c00460

Cited by 81 publications

(38 citation statements)

References 104 publications

(145 reference statements)

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“…Dozens of gas drainage methods and technologies are known internationally [22]. The most effectively used methods of gas drainage are those where methane is drained from the stress-relieved coal seam [23,24]. The effectiveness of these methods is over 80%, which from a cause-and-effect viewpoint is due to the extraction of liberated gas.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Intensive In-Seam Gas Drainage Technology at Kirova Mine in Kuznetsk Coal Basin

et al. 2022

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One of the ways to resolve the “green energy-economic development” dilemma, in which the coal industry is situated, is by the improvement of technologies and the integrated use of extracted resources, including methane gas as a clean energy source. Using the example of the Kirova mine, located in Kuznetsk coal basin—one of the ecologically unfavorable coal mining regions of Russia—this article discusses an integrated technology for the extraction of coalbed methane (ECBM), which makes it possible to reduce greenhouse gas (methane) emissions and improve the safety and intensity of coal mining. The Kirova mine, with its 3 Mt production in 2019, is one of the coal mining leaders in Russia. The available mining equipment has the potential to significantly increase the output; however, gas is a limiting factor to this. The customary approaches to coal seam degassing have already been petered out. The miners and mine science are facing a challenge to validate and test an alternative technology to ensure effective in-seam gas drainage prior to vigorous mining. This article gives an account of the improvement track record of the in-seam gas drainage technology used to pre-treat coal seams for intensive and safe extraction. This technology suggests, at the first stage, hydraulic loosening of the target coal seam through wells drilled from the surface (SSHL), then hydraulic fracturing (HF) of the coal seam through the boreholes drilled from underground development headings, followed by methane extraction from the high-permeability coal-gas reservoir created through standard in-seam gas drainage underground wells. Results are presented in this paper of field testing of the improved SSHL technique. Findings are presented on the effective parameters of the HF technology. Methodological recommendations are offered for selecting viable in-seam gas drainage technology.

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Section: Introductionmentioning

confidence: 99%

Improvement of Intensive In-Seam Gas Drainage Technology at Kirova Mine in Kuznetsk Coal Basin

et al. 2022

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“…12,13 The microstructure of coal remains largely unchanged during coalification and tectonic overprint but is modified in the engineering mining process due to external conditions. [1][2][3]14,15 For example, to enhance ECBM, artificial measures are usually applied to modify the physical structure of coal reservoirs, and then to achieve an increase in the reservoir permeability or promote CBM desorption. 1,15 Hydraulic fracturing is a widely used and effective technique to enhance ECBM by artificially increasing fractures and changing the coal microstructure to achieve an increased permeability.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3]14,15 For example, to enhance ECBM, artificial measures are usually applied to modify the physical structure of coal reservoirs, and then to achieve an increase in the reservoir permeability or promote CBM desorption. 1,15 Hydraulic fracturing is a widely used and effective technique to enhance ECBM by artificially increasing fractures and changing the coal microstructure to achieve an increased permeability. Fracturing fluids play an important role in this process 16 as they can enhance the fracturing effect and may also cause modifications of the microstructure of coal, thus influencing the effect of ECBM.…”

Section: Introductionmentioning

confidence: 99%

“…Fracturing fluids play an important role in this process 16 as they can enhance the fracturing effect and may also cause modifications of the microstructure of coal, thus influencing the effect of ECBM. 1,15,17 Hussain et al 18 found that viscoelastic fracturing fluid can not only effectively enhance the effect of fracturing fluid but also increase oil and gas production by dissolving minerals, dredging pores, and fractures, reducing blockage. Lu et al 19 studied the effect of cationic fracturing fluid on soft coal, and the results showed that the permeability of coal was greatly improved after treatment.…”

Section: Introductionmentioning

confidence: 99%

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Coupling Effect of Temperature, Gas, and Viscoelastic Surfactant Fracturing Fluid on the Microstructure and its Fractal Characteristics of Deep Coal

Wang

et al. 2021

Energy Fuels

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The study of the microstructure evolution law of coal in a natural reservoir environment for the extraction of coalbed methane mining (ECBM), especially deep ECBM, is of major significance. We treated coal samples from Qinshui Basin under combined temperature–gas–fracturing fluid conditions and analyzed the evolution of the microstructure and its fractal characteristics to study the microstructural evolution of coal under natural hydraulic fracturing conditions. In the temperature range of 303.15 to 343.15 K and the gas-pressure range of 0.5–4.5 MPa, our data demonstrate that the pore structure is more susceptible to the temperature influence, compared with microfracture. The treatment of viscoelastic surfactant fracturing fluid (VES-FF) can effectively increase the permeation pore and fracture ratio by more than 300% and reduce the adsorption pore by more than 200% through dissolution, gas wedge, and other effects, which is favorable to ECBM. At the same temperature, as the gas pressure increases, the pore decreases, whereas the fracture ratio increases. The pore fractal dimension ranges from 2.90 to 2.99, which is significantly higher than that of microfractures. The temperature has a minor effect on the fracture fractal dimension, but it causes a decrease in the pore fractal dimension. The treatment of VES-FF induces an increase in the fracture fractal dimension, implying an increase in the fractal complexity. In contrast, the pore fractal characteristics show a contrary trend. At a gas pressure of 4.5 MPa, the negative effect of VES-FF on the pore structure reaches its maximum, whereas the effect on the fracture drops to its minimum. The results document that high temperature and high gas pressure can severely limit the penetration enhancement effect of VES-FF.

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“…It is worth mentioning that gassy and outburst coal mines contribute over 30% of the coal production in China. As a result, significant casualties and equipment and property losses have been reported occasionally; thus, coal and gas outburst poses a serious threat to coal-mine safety production, with about 95% of the high gas and outburst collieries belonging to low-permeability coal seams, thus making it difficult to extract the gas directly, let alone overcome coal and gas outburst. − Consequently, it is urgently needed to improve the coal seam permeability and enhance gas drainage in low-permeability coal mines.…”

Section: Introductionmentioning

confidence: 99%

Response Characteristics of Coal Measure Strata Subjected to Hydraulic Fracturing: Insights from a Field Test

et al. 2021

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Hydraulic fracturing (HF) is an effective method to improve the permeability of coal seams and enhance coalbed methane recovery in underground coal reservoirs. However, the induced stress and strain evolution behaviors triggered by HF engineering practice remain unclear, which hinders our perception and field applications on HF technology. In this work, an HF field experiment was conducted in a deep buried coal mine, and a hollow inclusion cell (HI cell) was proposed to investigate the induced strain and stress evolution behaviors of HF. In addition, the HF complete evolution process was sectioned and comprehensively studied. The results showed that the influence range of this HF field test exceeds 44 m, and the induced strain primarily experiences three stages when subjected to HF: initial constancy, strain fluctuation, and later, stability. The induced stress experiences intense variations when subjected to HF, with the minimum principal stress increment being the greatest. Principal stress tends to recover to the initial stress state after HF, but the recovery speed declines with time. Further, azimuth and dip angle experience intense changes under HF. The change law is irregular, but they all tend to return to the primary state. Moreover, combining water flow and pressure, the HF evolution process can be divided into five stages: prehydraulic fracturing, unstable crack propagation, stable crack propagation, posthydraulic fracturing, and pump off stage, which can reflect the real evolution behaviors accurately. The research results have profound implications for coalbed methane recovery and coal mine gas governance.

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Current Status and Effective Suggestions for Efficient Exploitation of Coalbed Methane in China: A Review

Cited by 81 publications

References 104 publications

Improvement of Intensive In-Seam Gas Drainage Technology at Kirova Mine in Kuznetsk Coal Basin

Improvement of Intensive In-Seam Gas Drainage Technology at Kirova Mine in Kuznetsk Coal Basin

Coupling Effect of Temperature, Gas, and Viscoelastic Surfactant Fracturing Fluid on the Microstructure and its Fractal Characteristics of Deep Coal

Response Characteristics of Coal Measure Strata Subjected to Hydraulic Fracturing: Insights from a Field Test

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