Energy-limiting factor for coal and gas outburst occurrence in intact coal seam

2021 ◽  
Author(s):  
Qingyi Tu ◽  
Yuanping Cheng ◽  
Sheng Xue ◽  
Ting Ren ◽  
Xiang Cheng
Keyword(s):  
Coal Seam ◽  
Coal And Gas Outburst ◽  
Limiting Factor ◽  
Gas Outburst

Coal and gas outburst mechanism of the “Three Soft” coal seam in western Henan

2010 ◽  
Vol 20 (5) ◽  
pp. 712-717 ◽  
Author(s):  
Dongji LEI ◽  
Chengwu LI ◽  
Zimin ZHANG ◽  
Yugui ZHANG
Keyword(s):  
Coal Seam ◽  
Coal And Gas Outburst ◽  
Gas Outburst ◽  
Soft Coal ◽  
Soft Coal Seam

Deformation Degree Estimate for Coal Seam using Well Logs as Input: A Case Study

2018 ◽  
Vol 23 (1) ◽  
pp. 89-101
Author(s):  
Tongjun Chen ◽  
Guodong Ma ◽  
Xin Wang ◽  
Ruofei Cui
Keyword(s):  
Cluster Analysis ◽  
Wavelet Analysis ◽  
Coal Seam ◽  
Large Scale ◽  
Coal And Gas Outburst ◽  
Well Logs ◽  
Deformation Degree ◽  
Ternary Diagrams ◽  
Medium Scale ◽  
Gas Outburst

The presence of tectonic deformed coal (TDC) is a prerequisite for coal-and-gas outburst. With a higher degree of TDC deformation, there is a greater possibility of coal-and-gas outbursts. The estimate of deformation degree for coal seam is critically important for mining safety. In this study, we focus on the No. 8 coal seam of Luling coalmine to identify and estimate its deformation degree using well logs, multiscale wavelet analysis, cluster analysis, and ternary diagrams. Since the original well logs contain noise, we first perform denoising with multi-scale wavelet analysis and produce their large-scale and medium-scale output components. Then, we classify the No. 8 coal seam into different sub lithological seams with cluster analysis using the large-scale and medium-scale components as inputs. The classified sub lithological seams include the undeformed coal, the cataclastic coal, the granulated coal, the mylonitized coal, and the gangue. Finally, we group the study area into four regions based on degree of deformation with ternary diagrams using classified sub seam thickness as input. The regions with III and IV deformation degrees are mostly composed of highly deformed TDCs and are prone to coal-and-gas outburst. [Figure: see text]

scholarly journals Risk assessment method of coal and gas outburst based on improved comprehensive weighting and cloud theory

2021 ◽  
pp. 014459872110558
Author(s):  
Chunhua Zhang ◽  
Dengming Jiao ◽  
Ziwen Dong ◽  
Hongyu Zhang
Keyword(s):  
Risk Assessment ◽  
Coal Seam ◽  
Ideal Point ◽  
Assessment Method ◽  
Coal And Gas Outburst ◽  
Coal Seams ◽  
Gas Outburst ◽  
Risk Assessment Method ◽  
Cloud Theory ◽  
Assessment Results

Risk assessment is an effective method of accident prevention and is vital to actual production. To reduce the risk of mining accidents and realize green and sustainable coal mining, a coal and gas outburst risk assessment method based on the improved comprehensive weight and cloud theory is proposed. The proposed method can effectively solve problems of fuzziness and randomness, index weight deviation, and correlation between indexes in risk assessment, as well as improve the accuracy and rationality of assessment. Nine influencing factors that correspond to coal seam occurrence and geological characteristics, coal seam physical characteristics, and gas occurrence characteristics are selected to establish the risk assessment index system of coal and gas outburst. Using the improved group G1 method and improved CRITIC method to obtain the subjective and objective weights, the ideal point method is used to obtain the comprehensive weight. Using the normal cloud model of cloud theory and the comprehensive weight to assess engineering examples 1–2, the No. 3 coal seam of a mine in Shanxi, and the 21 coal seam of a mine in Henan, the risk grade of coal and gas outburst is determined and then compared with the assessment results obtained from the engineering examples and the actual situations of the above mentioned coal seams. The results show that the coal and gas outburst risks of engineering examples 1–2, No. 3 coal seam, and 21 coal seam are of grades IV, IV, II, and IV, respectively. The No. 3 coal seam and 21 coal seam belong to lower and higher risk categories, respectively. The assessment results are consistent with the actual situation of the coal seams, thereby confirming the rationality and accuracy of the proposed method. This study expands the methods of coal and gas outburst risk assessment and facilitates the formulation of effective preventive measures.

Features of Jianshanchong Klippe and its Control to Gas Geology at Qingshan Coal Mine, Jiangxi Province

2012 ◽  
Vol 164 ◽  
pp. 501-505
Author(s):  
Zhi Gen Zhao ◽  
Jia Chen ◽  
Jia Ping Yan
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Emission Rate ◽  
Coal And Gas Outburst ◽  
Jiangxi Province ◽  
Coal Seams ◽  
Gas Emission ◽  
Gas Outburst ◽  
Transverse Profile ◽  
Tectonic Coal

The coal and gas outburst is serious at Qingshan Coal Mine of Jiangxi Province, so it is of significance to research the features of Jianshanchong klippe and its control to gas geology. The research reveals that: Jianshanchong klippe is distributed from the east boundary of Qingshan Coal Mine to No. 45 Exploration Line, its transverse profile is like a funnel while its longitudinal profile is like a wedge, northwest side of the klippe is thicker and deeper while southeast side is thinner and more shallow. Because of the cover and insert of Jianshanchong klippe, the structure of coal-bearing strata is more complex, some secondary folds are formed, and also, the coal seam is changed greatly, the tectonic coal is well developed and the coal seam is suddenly thickening or thinning. Due to the effect of Jianshanchong klippe, the coal and gas outbursts occur in the area of secondary folds, thicker coal seams or tectonic coals. Concerning the prediction of gas geology in deep area, in view of the facts including simpler structure, stable coal seam and decreased thickness, the gas emission rate and the coal and gas outburst will decrease in Fifth and Sixth Mining Level than that in Second and Third Mining Level

scholarly journals Coal and gas outburst prevention using new high water content cement slurry for injection into the coal seam

2017 ◽  
Vol 27 (4) ◽  
pp. 669-673 ◽  
Author(s):  
Peiling Zhou ◽  
Yinghua Zhang ◽  
Zhi'an Huang ◽  
Yukun Gao ◽  
Hui Wang ◽  
...  
Keyword(s):  
Coal Seam ◽  
Water Content ◽  
High Water ◽  
Coal And Gas Outburst ◽  
High Water Content ◽  
Cement Slurry ◽  
Gas Outburst

Technology of Strip Gas Pre-Drainage with Boreholes along Coal Seam from Front Traverse

2012 ◽  
Vol 524-527 ◽  
pp. 752-757 ◽  
Author(s):  
Li Wei Chen ◽  
Jin Chao Chen
Keyword(s):  
Coal Seam ◽  
Coal And Gas Outburst ◽  
Gas Content ◽  
Low Permeability ◽  
Test Results ◽  
Gas Outburst ◽  
Short Period ◽  
Rock Roadway

In order to improve the heading speed of the seam gateway and mitigate the problem of mining maladjustment in high-gas mines and coal and gas outburst mines which are almost low permeability, highly-gas content and it is difficult to eliminate the gas-outburst dangerous by the conventional pre-drainage technologies in a short period. The paper puts forward the view of strip gas pre-drainage with boreholes along coal seam from front traverse of the rock roadway over the seam roof, which can greatly save the time of gas pre-drainage to eliminate gas outburst dangerous by drilling and gas pre-drainage simultaneously for the trips between two traverses. The test results showed that the ratio of roadway driving to gas pre-drainage were increased from 0.31 to 3.6,the speed of driving increased from 50m to 105m per month and the time of roadway drilling and blasting heading per hundred meters from78 days reduced to 19 days. So this technology can greatly mitigate the replacement contradiction of mining and roadway driving.

scholarly journals Elimination of Coal and Gas Outburst Dynamic Disasters in Dengfeng Coalfield through Gas Extraction Based on Extremely Thin Protective Coal Seam Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Haibo Liu ◽  
Xucheng Xiao ◽  
Zhihang Shu
Keyword(s):  
Coal Seam ◽  
Coal And Gas Outburst ◽  
Comprehensive Treatment ◽  
Cross Layer ◽  
Gas Extraction ◽  
Pressure Relief ◽  
Gas Outburst ◽  
Geological Conditions ◽  
Fracture Development ◽  
Seam Mining

No. 21 coal seam is a full-thickness structured soft coal in Dengfeng coalfield. The coal seam gas-bearing capacity is high, and the permeability is poor, thus resulting in serious coal and gas outburst dynamic disasters. According to the gas geological conditions of Baoyushan Mine, No. 17 coal seam without outburst danger, which is 0.5 m thick and 23.4 m under No. 21 coal seam, was mined in advance as the lower protective seam. At the same time, a gas extraction roadway was constructed in No. 21 coal seam floor. Cross-layer boreholes were constructed to extract the pressure relief gas of No. 21 coal seam for comprehensive treatment of mine gas. The mobile deformation of the overburden coal and rock mass after mining No. 17 coal seam, the fracture development characteristics of No. 21 coal seam, the pressure relief gas migration of the coal seam, the gas extraction, and the outburst danger elimination were studied. The research findings showed the following: (1) after mining No. 17 coal seam, the overburden hard and extremely thick limestone roof sagged slowly, albeit leading to no craving zone. (2) The permeability of No. 21 coal seam was increased by about 394 times, from 0.0012 mD to 0.4732 mD. (3) After the extraction of pressure relief gas through the gas extraction roadway on the floor through the cross-layer borehole, the gas pressure of No. 21 coal seam decreased from 1.17 MPa to 0.12 MPa, while the gas content decreased from 9.74 m3/t to 3.1 m3/t, which suggested that the coal and gas outburst dynamic danger of No. 21 coal seam was totally eliminated and the goal of safe and efficient mining in the mine was realized.

scholarly journals Discussion on the Mechanism of Coal and Gas Outburst Prevention and Control by the Coal Seam Water Injection

2019 ◽  
Vol 252 ◽  
pp. 052090 ◽  
Author(s):  
Jufeng Zhang ◽  
Riyun Wang ◽  
Fengfeng Yang ◽  
Wulin Lei ◽  
Biyang Feng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Prevention And Control ◽  
Water Injection ◽  
Coal And Gas Outburst ◽  
Gas Outburst ◽  
And Control

Elimination of coal and gas outburst risk of an outburst-prone coal seam using controllable liquid CO2 phase transition fracturing

Fuel ◽  
2021 ◽  
Vol 284 ◽  
pp. 119091
Author(s):  
Haidong Wang ◽  
Zhiheng Cheng ◽  
Quanle Zou ◽  
Zhenhua Li ◽  
Fulong Sun ◽  
...  
Keyword(s):  
Phase Transition ◽  
Coal Seam ◽  
Coal And Gas Outburst ◽  
Gas Outburst ◽  
Liquid Co2
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