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 A numerical simulation of realistic top coal caving intervals under different top coal thicknesses in longwall top coal caving working face

2021 ◽  
Author(s):  
Chuang Liu ◽  
Huamin Li
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Distinct Element ◽  
Simulation Models ◽  
Simulation Software ◽  
Thick Coal Seam ◽  
Coal Recovery ◽  
Working Face ◽  
Longwall Top Coal Caving ◽  
Selection Of

Abstract In the process of longwall top coal caving, the selection of the top coal caving interval along the advancing direction of the working face has an important effect on the top coal recovery. To explore a realistic top coal caving interval of the longwall top coal caving working face, longwall top coal caving panel 8202 in the Tongxin Coal Mine is used as an example, and 30 numerical simulation models are established by using Continuum-based Distinct Element Method (CDEM) simulation software to study the top coal recovery with 4.0 m, 8.0 m, 12.0 m, 16.0 m, 20.0 m and 24.0 m top coal thicknesses and 0.8 m, 1.0 m, 1.2 m, 1.6 m and 2.4 m top coal caving intervals. The results show that with an increase in the top coal caving interval, the single top coal caving amount increases. The top coal recovery is the highest with a 0.8 m top coal caving interval when the thickness of the top coal is less than 4.0 m, and it is the highest with a 1.2 m top coal caving interval when the coal seam thickness is greater than 4.0 m. These results provide a reference for the selection of a realistic top coal caving interval in thick coal seam caving mining.

scholarly journals Numerical Simulation of Borehole Parameters for Coal Seam Gas Pre-Drainage

2021 ◽  
Vol 39 (4) ◽  
pp. 1328-1334
Author(s):  
Xiaoyan Li ◽  
Jiyu Zheng ◽  
Jinpin Liu
Keyword(s):  
Numerical Simulation ◽  
Pressure Drop ◽  
Gas Pressure ◽  
Borehole Diameter ◽  
Gas Drainage ◽  
Drainage Time ◽  
Drainage Radius ◽  
Simulation Results ◽  
The Impact ◽  
The Relationship

Borehole parameters are quite important for gas drainage. This paper studies the impact of borehole diameter and time on gas drainage and performs numerical simulation on the distribution of gas pressure under the conditions of different borehole diameters and drainage times. The simulation results reveal that, as the borehole diameter increases, the gas drainage volume increases along with it and the gas pressure decreases, but such effect on gas drainage is limited. In terms of drainage time, the longer the drainage time, the greater the drainage impact scope. Taking a gas pressure drop of 51% as the indicator of the effective pre-drainage radius, the distance from the point with a gas pressure drop of 51% to the position of the borehole is the effective pre-drainage radius. When the pre-drainage reached the 30th, 45th, 60th, 75th, and 90th day, the effective pre-drainage radius was 1.04m, 1.29m, 1.51m, 1.68m, and 1.82m respectively. According to the numerical simulation results, the effective pre-drainage radius varies with the pre-drainage time, and the fitting analysis of the two indicates that the relationship between the two can be described by a power function.

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.

The Parameter Optimization and Field Application of Truss Cable Support System in a Thick Fragmental Coal Seam Roadway

2012 ◽  
Vol 524-527 ◽  
pp. 382-386
Author(s):  
Xiao Kang Zhang ◽  
Hong Jun Jiang ◽  
Fu Lian He ◽  
Ming Yue Weng
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Parameter Optimization ◽  
Support System ◽  
Coal Mine ◽  
Field Application ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Set Up ◽  
Main Support

For the support problem of set-up room to be 7.8m wide with thick and broken coal roof in Pangpangta coal mine, the truss cable support system is adopted to control the set-up room surrounding rock. The main support parameters, such as cable length, cable angle and distance between orifice and side of the truss cable support system are simulated and optimally designed by using numerical simulation software FLAC3D, by which the support scheme is designed reasonably. The support scheme is successfully tested at set-up room No. 10101 in Pangpangta mine. The set-up room deformation is small, and the support system is safe and reliable. This kind of support technology can be widely used in the similar set-up rooms.

The Study on Roadway Layout in Coordination of Mining Coal Seams Base on Failure of Floor Strata

2014 ◽  
Vol 889-890 ◽  
pp. 1362-1374 ◽  
Author(s):  
Yong Zhang ◽  
Chun Lei Zhang ◽  
Chun Chen Wei ◽  
Ya Dong Liu ◽  
Shi Qing Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Simulation Software ◽  
Coal Seams ◽  
Group Coordination ◽  
Mining Coal ◽  
Two Sides

In order to make sure the reasonable roadway layout in lower seam of close coal mining group coordination in Lijiahao coal mine, firstly, applying the theoretical analysis and geological radar detection to get the influence depth of mining from the up coal seam 2-2 to the floor is about 20m, the results show that the thickness of complete strata is about 15m, then determining to use the outward alternate entries in lower seam roadway by using theoretical analysis. At last, determining the distance of outward alternate entries is 12-14m by using FLAC3D numerical simulation software to simulate the change of stress and displacement in roof floor and two sides of roadway.

scholarly journals Numerical simulation of realistic top coal caving intervals under different top coal thicknesses in longwall top coal caving working face

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chuang Liu ◽  
Huamin Li
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Distinct Element ◽  
Simulation Models ◽  
Simulation Software ◽  
Thick Coal Seam ◽  
Coal Recovery ◽  
Working Face ◽  
Longwall Top Coal Caving ◽  
Selection Of

AbstractIn the process of longwall top coal caving, the selection of the top coal caving interval along the advancing direction of the working face has an important effect on the top coal recovery. To explore a realistic top coal caving interval of the longwall top coal caving working face, longwall top coal caving panel 8202 in the Tongxin Coal Mine is used as an example, and 30 numerical simulation models are established by using Continuum-based Distinct Element Method simulation software to study the top coal recovery with 4.0 m, 8.0 m, 12.0 m, 16.0 m, 20.0 m and 24.0 m top coal thicknesses and 0.8 m, 1.0 m, 1.2 m, 1.6 m and 2.4 m top coal caving intervals. The results show that with an increase in the top coal caving interval, the single top coal caving amount increases. The top coal recovery is the highest with a 0.8 m top coal caving interval when the thickness of the top coal is 4.0 m, and it is the highest with a 1.2 m top coal caving interval when the coal seam thickness is greater than 4.0 m. These results provide a reference for the selection of a realistic top coal caving interval in thick coal seam caving mining.

Numerical Simulation on the Influence of Mining-Induced Fractures Field on Gas Drainage and its Application

2011 ◽  
Vol 90-93 ◽  
pp. 477-484
Author(s):  
Shu Jing Zhang ◽  
Yong Wei Peng ◽  
Yong Jiang Yu
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Gas Flow ◽  
Underground Mining ◽  
High Strength ◽  
Gas Pressure ◽  
Comsol Multiphysics ◽  
Coal Seam Gas ◽  
Gas Drainage ◽  
Induced Fractures

In order to study the influence of mining-induced fractures field on gas drainage,the paper adopts software of numerical simulation COMSOL Multiphysics to simulate gas drainage of coal seam under the condition of high-strength underground mining. The main aspects can be seen as the following: (1) In the case without considering the fractures, gas drainage in single hole, the gas pressure distribution showed a funnel-type distribution in space along the drainage holes around. (2) The orientation and direction of fractures play a major role on the flow field of gas. In the region that exits fractures, the distribution of gas pressure has a clear fluctuation and adjustment.(3) The numerical simulation of coal seam gas drainage that considered the fracture of coal mining, was closer to the true gas flow.

The Research of Gas Drainage Technology in Daning Coal Mine

2014 ◽  
Vol 580-583 ◽  
pp. 2558-2563 ◽  
Author(s):  
Zhong Ming Zhao ◽  
Gang Wang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Clean Energy ◽  
Gas Pressure ◽  
Emission Sources ◽  
Gas Emission ◽  
Gas Drainage ◽  
Drainage Rate ◽  
Safe Production

3# coal seam of Daning coal mine is outburst,thus severely restricting the safe production. Based on the analysis of gas emission sources and the logical drainage parameters, firstly, Daning coal mine arranged some drilling fields, then utilized the VLD-1000-type rig to drill boreholes, achieving the integrated gas drainage of the coal seam and goaf. Finally, there is a test on the drainage result. The results showed that, through this kind of integrated gas drainage technology, the highest value of gas pressure in the coal seam reduced to 0.63MPa from 1.95MPa after twelve months’ drainage, and the gas drainage rate of the whole mine reached 77.6%, achieving efficient use of gas clean energy.

scholarly journals A Case Study on the Gas Drainage Optimization Based on the Effective Borehole Spacing in Sima Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Ming Ji ◽  
Zhong-guang Sun ◽  
Wei Sun
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Research Result ◽  
Economic Benefits ◽  
Coal Industry ◽  
Gas Drainage ◽  
Field Coupling ◽  
Drainage Time ◽  
Working Face

Based on the dynamic expressions of permeability and porosity of the coal seam derived in the paper, a multiphysical field coupling numerical model of gas migration under the interaction of stress field and seepage field was established. The gas drainage project #3 Coal Seam operated by Sima Coal Industry Co., Ltd., was selected as the study object. Taking different drainage time periods in various positions of drainage holes into consideration, combined with the advance situation of the 1207 working face in the Sima Coal Mine, a mixed layout gas drainage scheme featured with the effective borehole spacing was obtained through the COMSOL multiphysics simulation. In addition, a series of field industrial tests were performed to validate the research result, revealing that comprehensively considering the extraction time of coal and optimizing the layout of extraction boreholes can effectively improve the engineering economic benefits.

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