scholarly journals Numerical simulation of borehole wall remodel during gas drainage

2021 ◽  
Vol 768 (1) ◽  
pp. 012009
Author(s):  
Lihua Li ◽  
Yong Chen
Keyword(s):  
Numerical Simulation ◽  
Borehole Wall ◽  
Gas Drainage

scholarly journals Determination of Long Horizontal Borehole Height in Roofs and its Application to Gas Drainage

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2647
Author(s):  
Gang Wang ◽  
Cheng Fan ◽  
Hao Xu ◽  
Xuelin Liu ◽  
Rui Wang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Fracture Zone ◽  
Coalbed Methane ◽  
High Efficiency ◽  
Gas Drainage ◽  
Methane Drainage ◽  
Working Face ◽  
Variation Characteristics

Accurately determining the height of the gas-guiding fracture zone in the overlying strata of the goaf is the key to find the height of the long horizontal borehole in the roof. In order to determine the height, in this study we chose the 6306 working face of Tangkou Coal Mine in China as a research example and used both the theoretical model and discrete element method (DEM) numerical simulation to find the height of the gas-guiding fracture zone and applied the height to drill a long horizontal borehole in the roof of the 6303 working face. Furthermore, the borehole was utilized to deep into the roof for coalbed methane drainage and the results were compared with conventional gas drainage measures from other aspects. The height of the gas-guiding fracture zone was found to be 48.57 m in theoretical model based on the bulk coefficient and the void ratio and to be 51.19 m in the DEM numerical simulation according to the temporal and spatial variation characteristics of porosity. Taking both the results of theoretical analysis and numerical simulation into consideration, we determined that gas-guiding fracture zone is 49.88 m high and applied it to drill a long horizontal borehole deep into the roof in the 6303 working face field. Compared with conventional gas drainage measures, we found that the long horizontal borehole has the high stability, high efficiency and strong adaptability for methane drainage.

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 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 Increasing Permeability of Coal Seam and Improving Gas Drainage Using a Liquid Carbon Dioxide Phase Transition Explosive Technology

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Wenrui He ◽  
Fulian He ◽  
Kun Zhang ◽  
Yongqiang Zhao ◽  
Hengzhong Zhu
Keyword(s):  
Phase Transition ◽  
Carbon Dioxide ◽  
Numerical Simulation ◽  
Blast Hole ◽  
Liquid Carbon ◽  
Gas Drainage ◽  
Liquid Carbon Dioxide ◽  
Drainage Hole ◽  
Drainage Effect ◽  
Coal Damage

The low permeability of coal seams makes gas drainage difficult in lots of coal mines. This study presents a low-temperature, safe, and efficient liquid carbon dioxide phase transition explosive technology (LCDPTET) to increase the permeability of coal, thereby improving the efficiency of gas drainage and eliminating the dangers of coal and gas outburst. Meanwhile, an integrated approach for experimental determination, numerical simulation, and field testing was applied to study the damage ranges of coal and to determine a reasonable spacing between the gas drainage hole and blast hole. A numerical simulation model of liquid carbon dioxide phase transition explosion (LCDPTE) was built, and the damage index M was introduced to analyze the degree and range of coal damage after explosion at different spacings between the blast hole and the gas drainage hole. Furthermore, another aim was the assessment of the permeability changes and comparison of the gas drainage effects of different borehole spacings. The results showed that as the borehole spacing became smaller, the degree of coal damage around the gas drainage hole increased, and the gas drainage effect improved. However, to avoid the collapse of the gas drainage hole, the gas drainage holes should not be located in the crushing zone caused by LCDPTE. Based on the numerical analysis conducted to guide the borehole arrangement of the field test, the latter was carried out to study the increasing ranges of permeability of coal and the drainage effect after explosion. The results indicated that LCDPTET could greatly improve the permeability of the coal seam and gas drainage efficiency. In addition, this new technology could not only improve the safety and efficiency of mine production but could also turn carbon dioxide into an effective energy source worthy of popularization and application.

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.

Model Test and Numerical Simulation for Directional Pressure Relief Blasting

2013 ◽  
Vol 779-780 ◽  
pp. 848-856 ◽  
Author(s):  
Ding Jun Xiao ◽  
Bin Li ◽  
Chuan Jin Pu ◽  
Hui Qi Zhou
Keyword(s):  
Numerical Simulation ◽  
Blast Hole ◽  
Three Dimensional ◽  
Bottom Wall ◽  
Borehole Wall ◽  
Dynamic Strain ◽  
Test Results ◽  
Pressure Relief ◽  
Free Face ◽  
Air Column

To study directional pressure relief blasting, cement mortar model tests are carried out. Protecting borehole wall, free-face wall and bottom wall are tested of the dynamic strain. Three-dimensional numerical simulation and numerical calculation of the tests are conducted by using LS-DYNA3D. The pressure values and test results of the protecting borehole wall, free-face wall and bottom wall with the same distance from the explosives are compared. Development and distribution of pressure regularity are analyzed; blast hole pressure relief effect of protecting borehole wall materials and bottom interval air column are explicated. The present results indicate that there is an obvious stress concentration phenomenon on the free-face wall, with an average pressure decrease rate of 26% from the free-face wall to the protecting borehole wall with the same distance to the explosive center, while the isolation materialPVCU plays a good directional protection. The pressure effect of the blast hole bottom air column on the blast hole is apparent. The simulation results are consistent with the experimental dates.

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