scholarly journals Study on the Optimization of a Gas Drainage Borehole Drainage Horizon Based on the Evolution Characteristics of Mining Fracture

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4499
Author(s):  
Tengteng Li ◽  
Bing Wu ◽  
Baiwei Lei
Keyword(s):  
Coal Mine ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Low Level ◽  
Working Face ◽  
Evolution Characteristics ◽  
Gas Disaster ◽  
Fracture Area ◽  
High Level ◽  
Initial Change

Gas disaster restricts the safety development of coal mine. The technology of high-level borehole gas drainage is an important means to reduce the gas concentration in goaf. In order to determine the best position of the end of gas drainage hole, in this paper, based on the geological conditions of Xinyuan coal mine 31009 working face, a series of numerical simulation is carried out; and through the field test, the dynamic change of gas concentration in different height of borehole is monitored. The results show that: When the working face advances to different distances, there are four characteristic distribution areas in the horizontal direction: the fracture area of the original rock stratum, fracture channel generation and development area, fracture channel mature area and fracture channel closure area. Although the drilling horizon is different, the change of gas concentration in drilling can be divided into four stages: gas stabilization stage, gas initial change stage, gas fluctuation stage and gas re-stabilization stage. The variation of borehole concentration can reflect the evolution characteristics of fracture area. The response time of gas change in different layers is also different. In the gas initial change stage and the gas re-stabilization stage, the low-level borehole first responds. The response of gas change in high-level drilling is a long process, so the effect of high-level drilling is better than that of low-level drilling. For 31009 working face, the best gas drainage layer is 32m, and the field gas drainage has achieved good practical results. This study can provide some guidance for the prevention and control of gas disaster in goaf.

scholarly journals Disastrous Mechanism and Concentration Distribution of Gas Migration in Fully Mechanized Caving Stope in Wuyang Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Li Chong ◽  
He Sifeng ◽  
Xu Zhijun
Keyword(s):  
Coal Mine ◽  
Concentration Distribution ◽  
Spontaneous Combustion ◽  
Concentration Field ◽  
Gas Migration ◽  
Coal Spontaneous Combustion ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Research Results ◽  
Working Face

The overrunning disaster of harmful gas tends to occur in the working face in thick coal seam with high gas concentration, as the fully mechanized caving stope has the characteristics of high mining intensity, high remnant coal, and high gas content. Therefore, the disastrous mechanism and concentration distribution of gas migration in fully mechanized caving stope are the theoretical basis for gas control scheme. Based on the 7607 working face in Wuyang coal mine, the gas emission quantity in working face is comprehensively analyzed by field measurement in this paper. The gas leakage field, oxygen concentration field, and gas concentration field in 7607 working face are simulated by establishing the equal proportional numerical model. Due to the increase of air leakage in working face caused by the high alley pumping drainage, the risk of coal spontaneous combustion is also analyzed, when gas extraction in goaf is carried out. The research results show that the gas drainage technology in high drainage roadway has a remarkable effect on the gas overrunning phenomenon. The gas concentration near the upper corner of the working surface has been reduced from 0.7%-1% to 0.5%. At the same time, it is necessary to pay attention to the risk of coal spontaneous combustion in the goaf for gas drainage in the high drainage roadway. The width of the oxidation zone in the goaf is about 25 m deeper than that before the drainage. Research results provide the references for gas control technology and coal spontaneous combustion prevention in similar working faces.

Gas Control Technology under Unstable Disturbance Stress

2015 ◽  
Vol 15 ◽  
pp. 26-34
Author(s):  
Wei Min Cheng ◽  
Lu Lu Sun ◽  
Gang Wang ◽  
Hong Yuan Qu
Keyword(s):  
Control Technology ◽  
Static Loads ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Pressure Step ◽  
Working Face ◽  
Gas Control ◽  
High Level ◽  
Roadway Deformation ◽  
Surrounding Rock Deformation

Under the action of unstable disturbance stress, the stress concentration and roadway deformation are serious when tunneling along the goaf with small pillar while the adjacent working face is mining. This leads to the abnormal gas discharge and the increase of gas emission, and the effectiveness of gas drainage is reduced. In order to eliminate the threat of gas, the dynamic gas control technology of tunneling along the goaf with small pillar under unstable disturbance stress has been researched. The main sources of loads are confirmed by the analysis of dynamic and static loads. Combined with the force analysis of roadway and pillar, the stress superposition level is affected by the relative location of heading face and working face, and the regional characteristics. The measured surrounding rock deformation of A4007 return roadway heading face fits the theoretical analysis and pressure step of working face. The dynamic gas control technology is researched from the aspects of air volume, high-level gas drainage and goaf drainage, and applied in A4007 working face. The gas has been well controlled with the gas concentration of top corner of 0.62% and gas concentration of return current of 0.35%. As a result of the flow control, the gas drainage has not casused spontaneous combustion.

scholarly journals Reasonable Scope of Kilometer Drilling in Lower Layer of Extrathick Coal Seam: A Case Study of Tingnan Coal Mine, China

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Delong Zou ◽  
Xiang Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Lower Layer ◽  
Maximum Depth ◽  
Support Pressure ◽  
Directional Drilling ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Working Face ◽  
Fracture Development

When stratified mining is adopted in high-gas and extrathick coal seam, a large amount of pressure-relief gas of the lower layer flows into the upper layer goaf along the cracks in the layer, resulting in upper layer working face to frequently exceed the gas limit. And ordinary drilling can no longer meet the requirements of the pressure-relief gas drainage of the lower layer. The 205 working face of Tingnan Coal Mine is taken as the test background in this paper, and based on the “pressure-relief and flow-increase” effect of the lower layer under the action of mining stress during the upper layer mining, the gas drainage of kilometer directional drilling in lower layer is studied. According to the distribution characteristics of support pressure before and after the working face, the pressure-relief principle, fracture development characteristics, and gas migration law of the lower layered coal body are analyzed in the process of advancing the upper layered working face in the extrathick coal seam with high gas. The maximum depth of goaf damage is calculated theoretically, and the Flac3D numerical simulation of the failure deformation of the 205 working face floor is carried out. It is found that the maximum depth of plastic failure of the lower layer is about 13 m. According to the plastic deformation of the lower layer under different vertical depths and the movement of coal and rock mass, it is determined that the reasonable range of kilometer directional drilling in the lower layer is 6–9 m below the floor vertical depth. From 15 m to 45 m in the two parallel grooves, there is no fracture failure with a sharp increase or decrease in the displacement in the local range. Meanwhile, in this part, the roof falling behind is not easy to compaction, and the displacement of the floor is large, which does not cause plastic damage. The degree of pressure relief is more sufficient, and the permeability of the lower layer is good. Therefore, drilling should be arranged as much as possible along the working face in this tendency range. The determination of reasonable arrangement range of kilometer directional drilling in extrathick coal seam provides reference index and theoretical guidance for industrial test of working face and also provides new ideas for gas control of stratified mining face in high-gas and extrathick coal seam.

scholarly journals Dynamic Secondary Borehole-Sealing Method for Gas Drainage Boreholes along the Coal Seam

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Wei Qin ◽  
Jialin Xu
Keyword(s):  
Abutment Pressure ◽  
High Water ◽  
Test Results ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Working Face ◽  
Opportune Time ◽  
Sealing Device ◽  
Better Than

Under the influence of advanced abutment pressure, the tightness of a borehole is destroyed, so secondary borehole sealing is needed; however, the opportune time for a secondary borehole sealing is unclear. In addition, current borehole-sealing devices do not have a secondary borehole-sealing functionality. In this paper, an opportunity election model of secondary borehole sealing was established, and a dynamic secondary borehole-sealing device was developed. In working face 3908 of the Kaiyuan Coal Mine, an in situ dynamic secondary borehole-sealing test was conducted. The test results show that the tightness of the boreholes sealed with high-water-expansion slurry is obviously better than that of the boreholes sealed with cement mortar and polyurethane. When a borehole is destroyed by the peak of the advanced abutment pressure, the secondary borehole-sealing measures can significantly improve borehole suction pressure, gas concentration, and gas drainage amount in the advanced abutment pressure loading stage.

Research of Coal Mine Gas Monitoring System Based on Technology Fusion of Wireless Sensor Network and 3DGIS

2011 ◽  
Vol 314-316 ◽  
pp. 2263-2267 ◽  
Author(s):  
Xiang Yun Wan ◽  
Hao Yang ◽  
Lan Hui Sun ◽  
Hao Min Tian ◽  
Zhan Feng Huang
Keyword(s):  
Wireless Sensor Network ◽  
Sensor Network ◽  
Monitoring System ◽  
Coal Mine ◽  
Wireless Sensor ◽  
Gas Monitoring ◽  
Gas Concentration ◽  
Coal Mine Gas ◽  
Gas Disaster ◽  
Mine Gas

At present, gas disaster is one of the main problems for Chinese coal industry. The prevention and control of gas accident is an important part of coal mine enterprise production safety. This paper uses wireless sensor network to collect the coal mine gas concentration parameter, transmits and stores the data to the server of gas monitoring system by information fusion of sink, and synchronously displays the data to the client in the state of three-dimensional space. When the gas concentration of monitored coal mine roadway is greater than the limit, the sound and light alarm will be trigged and the alarm area will be displayed. In the meantime, the information of contingency plan will be provided. The system gives a strong technical support for the early warning and controlling of gas disaster and provides a reference for the prevention of gas accidents in coal enterprises.

scholarly journals Numerical simulation study on gas drainage by interval hydraulic flushing in coal seam working face

2021 ◽  
pp. 014459872110102
Author(s):  
Shengrong Xie ◽  
Junqi Cui ◽  
Dongdong Chen ◽  
Ping Chen
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Coal Mine ◽  
Simulation Software ◽  
Gas Pressure ◽  
Gas Extraction ◽  
Gas Drainage ◽  
Drainage Radius ◽  
Working Face ◽  
Effective Drainage

In order to solve the problem of difficult gas extraction in coal mine, a method of gas extraction from coal seam by interval hydraulic flushing is put forward. Based on the coal seam gas occurrence conditions of 7609 working face in Wuyang Coal Mine, the numerical simulation research on gas drainage by ordinary drilling and hydraulic flushing drilling was carried out by using COMSOL numerical simulation software. The results show that with the increase of hydraulic flushing coal quantity, the effective gas drainage radius also increases. The effective extraction radius of ordinary drilling is 0.5 m, and the effective extraction radius is 1.0 m, 1.2 m and 1.3 m respectively when the coal flushing quantity is 0.5t/m, 1.0t/m and 1.5t/m. As multiple boreholes are drained at the same time, the boreholes will affect each other, which will reduce the gas pressure and increase the effective drainage radius, the spacing between boreholes can be greater than twice the effective drainage radius of a single borehole when arranging boreholes. And the smaller the flushing interval, the more uniform the gas pressure reduction area. According to the numerical simulation results, the ordinary drilling and 1.0t/m interval hydraulic flushing test were carried out in the field. Through observation and analysis, the gas concentration of the interval hydraulic flushing drilling module was increased by 31.2% and the drainage purity was increased by 5.77 times compared with the ordinary drilling module. It shows that the interval hydraulic flushing drilling can effectively improve the gas drainage effect.

scholarly journals Speculum Observation and Trajectory Measurement in Gas Extraction Drilling: A Case Study of Changling Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Enbiao Zhao ◽  
Kangnan Li ◽  
Xin Yang ◽  
Nan Deng
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Efficient Production ◽  
Drilling Process ◽  
Coal Seams ◽  
Adjacent Layer ◽  
Gas Drainage ◽  
High Level ◽  
Trajectory Measurement ◽  
Drainage Borehole

Coal will still be China’s basic energy for quite a long time. With the increase of mining depth, gas content and pressure also increase. The problems of gas emission and overrun affect the safety and efficient production of coal resource to a certain extent. In this work, the field test of gas drainage borehole peeping and trajectory measurement in coal seam of Changling coal mine are carried out. These coal seams include C5b coal seam, upper adjacent C5a coal seam, C6a coal seams, C6c in lower adjacent strata, and C5b coal seam in high-level borehole. The view of gas drainage borehole peeping and trajectory measurement in the working seam, upper adjacent layer, lower adjacent layer, and high position are obtained. It is found that the hole collapses at the position of about 20 m in both adjacent strata and high-level boreholes, and there are a lot of cracks in the high-level boreholes before 12 m. The deviation distance of high-level borehole is large, and the actual vertical deviation of upper adjacent layer is small. Finally, the strategies to prevent the deviation of drilling construction are put forward. It includes four aspects: ensuring the reliability of drilling equipment, reasonably controlling the drilling length, standardizing the drilling, and reasonably selecting the drilling process parameters.

scholarly journals Research on the Evolution Characteristics of Floor Stress and Reasonable Layout of Roadways in Deep Coal Mining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yang Yu ◽  
Lianying Zhang ◽  
Jianfei Lu ◽  
Dingchao Chen ◽  
Xiangqian Zhao ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Theoretical Calculations ◽  
Limit Equilibrium ◽  
Practical Significance ◽  
Infinite Plane ◽  
Horizontal Distance ◽  
Gas Drainage ◽  
Vertical Distance ◽  
Working Face ◽  
Evolution Characteristics

The safe and efficient mining of deep coal resources is severely restricted by the dynamic disasters caused by high gas and high ground stress. Taking a deep mine in China as the research background, a mechanical model of the front supporting stress with the working face was constructed through theoretical calculations. Based on the limit equilibrium theory, the stress distribution in the plastic zone and the elastic zone of the lateral working face was derived; based on semi-infinite plane mechanics model, the floor vertical and horizontal stress distribution was deduced. Then, the roadway surrounding rock stress and displacement field distribution evolution characteristics were revealed through numerical simulation. On this basis, the reasonable floor gas drainage roadway (FGDR) layout was determined: internal staggered layout was used with FGDR, the vertical distance to the working face is 20 m, and the horizontal distance to the working face end is 15 m; the open-off cut of FGDR was arranged in an external staggered layout, the vertical distance to the working face is 20 m, and the horizontal distance to the open-off cut of the working face is 15 m. It is an important practical significance for the layout of FGDR, the control of surrounding rocks, and the improvement of gas drainage effects under similar conditions through the research results.

scholarly journals Comprehensive Control Method of Gas in Upper Corner of High Strength Fully Mechanized Coal Mine

2021 ◽  
Vol 233 ◽  
pp. 01009
Author(s):  
Huijun Duan ◽  
Shijun Hao ◽  
Xu Peng
Keyword(s):  
Coal Mine ◽  
Control Method ◽  
High Strength ◽  
Gas Content ◽  
Engineering Practice ◽  
Directional Drilling ◽  
Gas Emission ◽  
Gas Concentration ◽  
Working Face ◽  
Mining Face

Based on the problem of large gas emission and serious gas accumulation in upper corner of the intensive fully mechanized caving face, taking the fully mechanized caving face of Wangjialing Coal Mine in Hedong Mine as the research object, the main gas emission sources of the extremely intensive mining face with low permeability and low gas content were studied. The methods of gas extraction by inserting (burying) pipe in upper corner and directional drilling in upper corner were adopted and carried out. The application of engineering practice and comparative test of effect are carried out. The results show that the maximum extraction purity is 2.8 m³/min, the maximum gas concentration is 0.8% in upper corner, 3.11 m³/min in the high directional borehole and 0.71% in upper corner. After combined extraction, the total extraction purity is 1.33~7.93 m³/min and the fluctuation range of gas concentration in upper corner is reduced to 0.31~0.61% safe point. The effect of gas prevention and control in working face is remarkable.

The Study on Gas Drainage to Gob with Long Bore-Holes at ChangPing Coalmine

2012 ◽  
Vol 524-527 ◽  
pp. 387-390
Author(s):  
Jun Liu ◽  
Lin Wang ◽  
Xian Yao Xin
Keyword(s):  
Coal Mine ◽  
Economic Benefits ◽  
Actual Situation ◽  
Gas Emission ◽  
Gas Drainage ◽  
Working Face

Based on lots of gas emission from gob in mining faces, and the actual situation that gas accumulates in the top corner of the working face in Chang Ping coal mine, it is introduced in the paper that the successful experience about the technology of gas drainage to gob with long bore-holes along roof strike, the conclusion would be had obtained obvious security and economic benefits.

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