Experimental investigation on the formation and transport mechanism of outburst coal-gas flow: Implications for the role of gas desorption in the development stage of outburst

Jin, Kan; Wang, Chenghao; Ren, Ting X; Zhao, Wei; Tu, Qingyi; Dong, Jun; Wang, Zhenyang; Hu, Biao

doi:10.1016/j.coal.2018.05.012

Cited by 135 publications

(52 citation statements)

References 58 publications

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“…Coal and gas outbursts (hereinafter referred to as outbursts) in coal mines are complex dynamic phenomena characterized by a sudden and violent ejection of large amounts of coal and gas from the working face into a limited working space within a short time [ 1 , 2 , 3 , 4 ]. The pulverized coal and gas flow induced by an outburst generates an enormous amount of energy [ 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Research on Temperature Variation during Coal and Gas Outbursts: Implications for Outburst Prediction in Coal Mines

Zhang

Wang

et al. 2020

Sensors

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Coal and gas outbursts are among the most severe disasters threatening the safety of coal mines around the world. They are dynamic phenomena characterized by large quantities of coal and gas ejected from working faces within a short time. Numerous researchers have conducted studies on outburst prediction, and a variety of indices have been developed to this end. However, these indices are usually empirical or based on local experience, and the accurate prediction of outbursts is not feasible due to the complicated mechanisms of outbursts. This study conducts outburst experiments using large-scale multifunctional equipment developed in the laboratory to develop a more robust outburst prediction method. In this study, the coal temperature during the outburst process was monitored using temperature sensors. The results show that the coal temperature decreased rapidly as the outburst progressed. Meanwhile, the coal temperature in locations far from the outburst mouth increased. The coal broken in the stress concentration state is the main factor causing the abnormal temperature rise. The discovery of these phenomena lays a theoretical foundation and provides an experimental basis for an effective outburst prediction method. An outburst prediction method based on monitoring temperature was proposed, and has a simpler and faster operation process and is not easily disturbed by coal mining activities. What is more, the critical values of coal temperature rises or temperature gradients can be flexibly adjusted according to the actual situations of different coal mines to predict outbursts more effectively and accurately.

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Section: Introductionmentioning

confidence: 99%

Research on Temperature Variation during Coal and Gas Outbursts: Implications for Outburst Prediction in Coal Mines

Zhang

Wang

et al. 2020

Sensors

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“…Many efforts have been put on to explore the occurrence mechanism since the coal and gas outburst occurred in Issac coal mine, Luarelli coal eld, France in 1834. By now, the general mechanisms of coal and gas outburst is summed up in the following four manners: the gas leading role hypothesis, the geostress leading role hypothesis, the chemical effect hypothesis, and combination hypothesis which considered that the outburst is the result of combined effect of stress, gas and coal (An et al, 2019;Gao et al, 2019;Jin et al, 2018;. A variety of techniques and measures were taken to forecast and prevent coal and gas outburst.…”

Section: Introductionmentioning

confidence: 99%

Low-index Catastrophe Model of Deep Gas-bearing Coal Seams

Li¹,

2020

Preprint

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Abstract Coal and gas outburst always occur as some parameters reach its threshold in the mining process of gas-bearing coal seams. However, low-index catastrophes may happen in the deep mining although the parameters do not exceed its threshold values. This phenomenon has become a challenge for our traditional cognitions. In this paper, the mechanism of low-index catastrophes of high-stress area in the deep gas-bearing seams was investigated by the following methods including literature reviewing, on-site investigation, case analysis, physical experiments and theoretical analysis. The results indicate that there were not only primary state fissures but also many secondary fissures are formed after taking outburst eliminating measures, which is beneficial for improving the desorption performance of methane. A “three-zone” theory of gas migration in Coal Seams is given, coal seam in the front of coal mining face can be divided into three zones: the gas emission zone, the gas channel compaction zone, and disturbance gas desorption zone before reaching ultimate equilibrium, corresponding to coal and gas ejection zone, gas migration zone and gas launching zone after surpassing the limits. Importantly, the stress dike is redefined, and a new concept is proposed that the low-index catastrophe of gas bearing seams is caused by avalanche instability of the stress dikes, meanwhile its three modes are given by over static-load stress dike avalanche caused by hanging arch overlength, stress dike avalanche under roof breakage impact, and stress dike avalanche under floor breakage impact. In deep stress area, stress dike avalanche caused by dynamic-static loading could lead to low-index catastrophes of gas bearing seams. The insufficient residual gas energy could cause unusual gas emission. On the other hand, the sufficient gas energy may lead to coal and gas outbursts.

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“…In general, the permeability in the soft coal could be several orders of magnitude less than that in the hard coal . Therefore, its gas extraction is rather difficult, and thus, more than 20 thousand coal and gas outburst accidents have been reported in China in its coal mining history . This makes its coal mining industry the most outburst risk troubled sector in the world …”

Section: Introductionmentioning

confidence: 99%

Hydraulic flushing in soft coal sublayer: Gas extraction enhancement mechanism and field application

Zhang

Wang

Yuan

et al. 2019

Energy Science & Engineering

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In China, one or several ultrathin soft coal sublayers are widely developed in the coal seam. Therefore, a method of using hydraulic flushing in soft sublayer to enhance the gas extraction in these particular coal seams is developed in this work. We first established a new fully coupled gas extraction model by combing gas diffusion, gas flow, and a permeability model that considers the effect of stress change and plastic failure. By adopting this model, the gas extraction enhancement mechanism and its main influence factors were studied using the numerical simulation method based on the engineering and geological background in the Yangquan No.5 coalmine. Thereafter, a hydraulic flushing equipment, which could move freely in the underground coalmine, was developed to apply the hydraulic flushing method in soft coal sublayers used in the 8402 working face. Its gas extraction effect was systematically investigated. Our simulation results match well with the field results, suggesting that our model is feasible. Meanwhile, after adopting this method, the gas extraction condition in this coalmine improves significantly. The borehole number decreases by 66.7%, while the gas extraction rate and gas extraction concentration increase by 1.33 times and 3 times, respectively. Moreover, during the coal mining process, the gas adsorption index of drilling cuttings, the quantity of drilling cuttings, and the CH4 concentration also decrease dramatically.

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Experimental investigation on the formation and transport mechanism of outburst coal-gas flow: Implications for the role of gas desorption in the development stage of outburst

Cited by 135 publications

References 58 publications

Research on Temperature Variation during Coal and Gas Outbursts: Implications for Outburst Prediction in Coal Mines

Research on Temperature Variation during Coal and Gas Outbursts: Implications for Outburst Prediction in Coal Mines

Low-index Catastrophe Model of Deep Gas-bearing Coal Seams

Hydraulic flushing in soft coal sublayer: Gas extraction enhancement mechanism and field application

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