scholarly journals Research on Optimization of Key Areas of Drainage Borehole Sealing in Ultrathick Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Xin Guo ◽  
Sheng Xue ◽  
Yaobin Li ◽  
Chunshan Zheng ◽  
Linfang Xie
Keyword(s):  
Test Scheme ◽  
Actual Situation ◽  
Air Leakage ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Gas Leakage ◽  
Important Means ◽  
M 12 ◽  
Drainage Effect ◽  
Drainage Borehole

Gas drainage is an important means of gas control. The influence of the key position of the sealing hole on gas drainage was studied by theoretical and numerical simulation combined with field measurement to solve low gas concentration in gas predrainage boreholes in coal mines of China. By analyzing the distribution of cracks around the boreholes and the law of air leakage and simulating the drainage effect of different sealing areas (8 m, 12 m, and 16 m), it was proposed that the key position of the sealing hole should be in the prepeak stress concentration area. According to the actual situation of Baode Mine, the sealing test scheme of different sealing areas was put forward, and the field test was carried out to obtain the key sealing area of gas predrainage boreholes in Baode Mine. Research shows that when the sealing area is 8–16 m, the average gas concentration is 63.57%, and the average pure gas flux is 0.408 m3/min. The sealing effect of this area is better, with fewer cracks, than that of the existing sealing area, effectively preventing gas leakage and increasing the gas concentration and gas scalar.

scholarly journals Gas Distribution Mechanism in Goaf during Combined Drainage of Upper Corner Buried Pipeline and Intubation for Thick Coal Seams

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Zhe Li ◽  
Fangtian Wang ◽  
Shuai Ren ◽  
Guannan Liu
Keyword(s):  
Buried Pipeline ◽  
Coal Seams ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Geological Conditions ◽  
Key Issues ◽  
Fluent Software ◽  
Gas Control ◽  
Drainage Effect ◽  
And Control

Abstract The prevention of gas overrun in the panel is one of the key issues on green mining. In this paper, a physical goaf model was established based on the geological production conditions of a coal seam in a coal mine in Henan Province, and the combined drainage technology by burying and spilling pipeline in the upper corner was proposed. The Fluent software was used to simulate the changes of gas mass fraction and flow field distribution when the gas is extracted from the goaf without the gas pipeline, with a single buried pipeline, and with the combination of buried and spilled pipelines. Analysis and simulation showed that in the absence of drainage pipelines, the gas concentrations in both the return airway and the upper corner are up to 1.2%, which failed to meet the gas prevention and control standard on the mine. In the case of gas drainage with a single buried pipeline, the average gas concentration in the return airway was 0.7%, and only the gas concentration in the upper corner was up to 1.1%, which failed to meet the gas control standards on the mine’s panel. However, the maximum gas concentration in the combined drainage was reduced from 1.1% to 0.6%, which indicates that the technology can greatly reduce gas concentration, but there is still a gap from the mine’s gas control standard. Therefore, the impacts of the lengths of pipelines buried in different goafs on the gas drainage effect in the goaf were studied, and it was concluded that the reasonable length of pipelines buried in the goaf under the geological conditions was 20 m. This technology not only solves the problem of gas overrun in the panel but also realizes the utilization of gas resources in the goaf. The research results are of guiding significance for pipeline laying and the drainage technology in the upper corners on the U-shaped ventilation panel.

scholarly journals Improvement of Gas Drainage Efficiency via Optimization of Sealing Depth of Cross-Measure Boreholes

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Pu Li ◽  
Zhiheng Cheng ◽  
Liang Chen ◽  
Hongbing Wang ◽  
Jialin Cao
Keyword(s):  
Stress Concentration ◽  
Drainage System ◽  
Stress Concentration Zone ◽  
Concentration Zone ◽  
Air Leakage ◽  
In Situ Tests ◽  
Gas Drainage ◽  
Drainage Borehole

The sealing depth of a gas-drainage borehole is critically important as it directly affects the efficiency of the whole drainage system. In order to determine the shortest reasonable sealing depth, in this paper, a theoretical drainage model using different sealing depths was proposed. Based on theoretical analysis presented, two parts of the fractures system surrounding the drainage borehole were proposed, i.e. the fractures induced by roadway excavation and the fractures induced by borehole drilling. A series of geological in-situ tests and simulations research were conducted to determine the stress and fracture distributions in the surrounding rock of the borehole. The depths of crushing zones, plastic zones and stress concentration zones were determined as 5 m, 2 m and 12 m, respectively. Meanwhile, stress simulation shows that the depth of the stress concentration zone was 12 m from the roadway wall and the stress peak was located at the depth of 8 m, which can be verified by the results of drilling penetration velocity analysis. To determine the optimum sealing depth, gas drainage holes with different sealing depths were drilled in the field. The field results revealed that the crushing zones were the main area for air leakage, and the stress concentration induced by roadway excavation assisted in the reduction of air leakage. Therefore, the optimized sealing depth should both cover the plastic zone and the stress concentration zone. The research achievements can provide a quantitative method for the determination of optimum sealing depth in cross-measure drainage boreholes.

scholarly journals Characterisation of mechanics and flow fields around in-seam methane gas drainage borehole for preventing ventilation air leakage: A case study

2016 ◽  
Vol 162 ◽  
pp. 123-138 ◽  
Author(s):  
Chunshan Zheng ◽  
Zhongwei Chen ◽  
Mehmet Kizil ◽  
Saiied Aminossadati ◽  
Quanle Zou ◽  
...  
Keyword(s):  
Flow Fields ◽  
Air Leakage ◽  
Gas Drainage ◽  
Methane Gas ◽  
Drainage Borehole

Stability of Gas Drainage Borehole Analysis on Rock Mechanics Parameters with Roadway of Complex Stress

2015 ◽  
Vol 723 ◽  
pp. 330-335 ◽  
Author(s):  
Tian Jun Zhang ◽  
Lei Zhang ◽  
Hong Yu Pan ◽  
Chao Zhang
Keyword(s):  
Numerical Simulation ◽  
Internal Friction ◽  
Rock Mechanics ◽  
Vertical Direction ◽  
Friction Angle ◽  
Complex Stress ◽  
Stress Redistribution ◽  
Horizontal Direction ◽  
Gas Drainage ◽  
Drainage Borehole

The pattern of stress redistribution in the effect of circular roadway is analyzed and numerical simulation on stability of gas drainage borehole which is in the area of the stress redistribution was done with FLAC3D. The model of that circular roadway and gas drainage borehole are perpendicularly crossed is established and compute with the Coulomb Mohr criterion. It can be found that the stress of gas drainage borehole decreases with decreasing of internal friction angle and the cohesion value. The stress of gas drainage borehole steep rises where the distances of away from roadway is two times of the diameter and the stress of horizontal direction are larger than the stress of vertical direction.

scholarly journals Influence of Deformation and Instability of Borehole on Gas Extraction in Deep Mining Soft Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xue-Bo Zhang ◽  
Shuai-Shuai Shen ◽  
Xiao-Jun Feng ◽  
Yang Ming ◽  
Jia-jia Liu
Keyword(s):  
Pressure Loss ◽  
Drainage System ◽  
Suction Pressure ◽  
Coal Seams ◽  
Gas Drainage ◽  
Soft Coal ◽  
Instability Modes ◽  
Deformation Instability ◽  
Effective Drainage ◽  
Drainage Effect

To study the effects of the three deformation instability modes of gas drainage borehole on gas drainage, the deformation instability mechanism of soft coal seams is analyzed, three deformation instability modes are proposed for soft coal seams, namely, complete holes, collapse holes, and plug holes, and a solid-fluid coupling model incorporating dynamic change of borehole suction pressure is established. The results of the study show the following. (1) When there is no borehole deformation (i.e., complete borehole), the suction pressure loss of drainage system in the borehole is very small, whose effect on gas drainage can be neglected. (2) In case of borehole collapse, the suction pressure loss is big at the collapse segment, and the total suction pressure loss of the drainage system in the borehole is bigger than that in the complete hole. However, it is smaller than the suction pressure of the drainage system and exerts limited effect on gas drainage. As the borehole collapse deteriorates, the effective drainage section of the borehole becomes smaller, while the suction pressure loss in the borehole increases continuously; thus, the gas drainage effect continuously worsens. (3) In case of plug hole, a continuous medium forms between the plug segment coal body and the surrounding coal seam, the plug segment drainage pressure turns into coal-bed gas pressure, and effective drainage length of the borehole shortens, seriously affecting the gas drainage effect. The study carries important theoretical guiding significance for improving gas drainage effect and effectively preventing gas disasters.

scholarly journals Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas-Bearing Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Renjun Feng
Keyword(s):  
Coupling Model ◽  
Specific Reference ◽  
Gas Migration ◽  
Quantitative Characterization ◽  
Gas Drainage ◽  
Drainage Time ◽  
Working Face ◽  
Drainage Effect ◽  
Gas Bearing

Gas drainage through long seam boreholes is an effective method to prevent gas disasters in coal mines. In this paper, a multifield coupling model of gas migration in gas-bearing coal was first established. Then, a quantitative characterization method of gas drainage effect was put forward. Finally, the extraction effect of long boreholes was obtained under different layouts and drilling lengths. The research results show that, under the arrangement of long boreholes along the seam, the gas pressure around the borehole decreases significantly with the extraction time. There is no extraction blank in the middle of the working face. However, it is easy to cause uneven gas drainage in the combined arrangement of the long boreholes along the seam and the penetrating boreholes. Furthermore, it is found that the drainage volume of the long boreholes along the seam is similar to that of the joint layout under the same drainage time. As the length of the borehole increases, the influencing range of gas drainage increases. When the borehole lengths are 150 m and 240 m, the drainage volumes are about 1.31 and 2.50 times that of the 90 m boreholes, respectively. The research achievements could provide a specific reference for the layout of long boreholes along the bedding and the determination of reasonable parameters for gas drainage on site.

scholarly journals Experimental and measured research on three-dimensional deformation law of gas drainage borehole in coal seam

2020 ◽  
Vol 30 (3) ◽  
pp. 397-403
Author(s):  
Hongbao Zhao ◽  
Jinyu Li ◽  
Yihong Liu ◽  
Yikuo Wang ◽  
Tao Wang ◽  
...  
Keyword(s):  
Coal Seam ◽  
Three Dimensional ◽  
Gas Drainage ◽  
Deformation Law ◽  
Drainage Borehole

The Application of Gas Drainage Technology in the Workface of "Three Soft" Specially Thick Coal Seam

2012 ◽  
Vol 204-208 ◽  
pp. 3469-3475
Author(s):  
Guo Liang Lu ◽  
Chen Wang ◽  
Yao Dong Jiang ◽  
Hong Wei Wang
Keyword(s):  
Coal Seam ◽  
Production Process ◽  
Low Permeability ◽  
Gas Drainage ◽  
Thick Coal Seam ◽  
Mine Area ◽  
Soft Coal ◽  
Drainage Effect ◽  
Soft Coal Seam

In order to improve the gas drainage effect of "three soft" coal seam with low-permeability and eliminate the gas overrun in the upper corner and return air during the production process, this paper did an exploration on the comprehensive gas management on the fully mechanized caving face of gassy mines in Xuangang mine area and its application achieved a good result.

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