Representation of mining permeability and borehole layout optimization for efficient methane drainage

Fan, Zhanglei; Fan, Guorong; Zhang, Dongsheng

doi:10.1016/j.egyr.2021.06.069

Cited by 11 publications

(7 citation statements)

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“…(2) The coal seam temperature is constant, and the law of coal seam gas desorption follows the Langmuir equation. (3) The relationship between the strain generated by the deformation of the gas-bearing coal rock and the effective stress follows the generalized Hooke's law.…”

Section: Model Assumptionsmentioning

confidence: 99%

“…The coal body's permeability is related to the development of its pore and fissure structure and the different stress states that can cause changes in the skeleton deformation and pore volume of the coal rock. 19 Therefore, the equation for the change in the stress field of gas-bearing coal, taking into account the ground stress, the adsorption of a gas by coal-rock particles, and the change in gas pressure is 3,12,20…”

Section: Deformation Field Control Equations For Gas-bearing Coal Rocksmentioning

confidence: 99%

“…The coal body's permeability is related to the development of its pore and fissure structure and the different stress states that can cause changes in the skeleton deformation and pore volume of the coal rock 19 . Therefore, the equation for the change in the stress field of gas‐bearing coal, taking into account the ground stress, the adsorption of a gas by coal–rock particles, and the change in gas pressure is 3,12,20

$\left\{\begin{array}{c}G\sum _{j=1}^{3}\displaystyle \frac{{\partial }^{2}{u}_{i}}{\partial {{x}_{i}}^{2}}+\displaystyle \frac{G}{1-2v}\sum _{j=1}^{3}\displaystyle \frac{{\partial }^{2}{u}_{i}}{\partial {x}_{i}{x}_{j}}+[a+\displaystyle \frac{2G}{3{K}_{s}}\,+(\displaystyle \frac{1-2v}{{V}_{m}}-\displaystyle \frac{2G}{3{V}_{m}{K}_{s}})\displaystyle \frac{2ab\rho RT}{3(1+bP)}]\displaystyle \frac{\partial P}{\partial {x}_{i}}+{F}_{i}=0,\\ k=\disp...

…”

Section: Modeling Of Coal–rock Flow–solid Couplingmentioning

confidence: 99%

“…In addition to being related to its pore and fracture structure, coal–rock body permeability can also cause deformation of the coal–rock skeleton and change in pore volume under different stress states 2 . Under the influence of mining, the permeability evolution of gas‐bearing coal–rock bodies is a complex process involving mining stress‐fracture‐seepage coupling, which is closely related to geological structure, rock properties, mining parameters, and ground stress 3–5 6,7 …”

Section: Introductionmentioning

confidence: 99%

“…2 Under the influence of mining, the permeability evolution of gasbearing coal-rock bodies is a complex process involving mining stress-fracture-seepage coupling, which is closely related to geological structure, rock properties, mining parameters, and ground stress. [3][4][5] Using the pressurerelieving effect generated by coal seam mining, the surrounding coal permeability can be influenced, resulting in a significant increase in gas drainage from nearby boreholes over time. 6,7 As the upper and lower rock seams are gradually expanded and deformed during cyclic incoming pressure after coal seam mining, the surrounding rock is subjected to layered cyclic unloading, which continuously produces plastic deformation and the corresponding permeability gradually increases with stress unloading.…”

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confidence: 99%

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Study on time–space characteristics of gas drainage in advanced self‐pressure‐relief area of the stope

Jie

Wang

Dongdong

et al. 2023

Energy Science & Engineering

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Gas drainage is an important measure to ensure energy safety in coal mines. However, for mines with high gas content and low permeability, the critical question is how to enhance the drainage effect of drilling. By using the self‐unloading pressure effect on the coal body in front of the mine, the permeability of the coal body can be improved, which facilitates gas drainage. Therefore, establishing the fluid–solid model of gas‐bearing coal mass under the influence of mining, this paper simulates the advanced self‐pressure‐relief range in front of the coal working face and the permeability of coal seam at different heights. Through simulations and field tests, the reasonableness of the advanced self‐pressure‐relief gas drainage was verified, and the spatial and temporal characteristics of the gas drainage from the borehole were quantified and analyzed. The results show that the width of the advanced self‐pressure‐relief zone after simulated mining is 25 m, the vertical permeability of the coal seam increases first and then decreases with the increase of the height from the floor, and the maximum permeability of the layer is 2.6 m from the floor, which is 8.62 times higher than the initial permeability; the gas drainage effect of test boreholes has a periodic law with the coal seam recovery, which, divided into the initial drainage stage, the scalar volume of gas drainage increase stage, and the scalar volume of gas drainage decay stage. At a distance from the working face 20–40 m, the boreholes' scalar volume of gas drainage increased by 3.89 times compared with the initial drainage stage, and the scalar drainage volume of the boreholes through the seam increased by 8.01 times compared with the initial drainage stage; in the section of increasing scalar volume of drainage, the gas drainage volume of the boreholes at different heights of the coal seam had obvious “stratification” phenomenon. The test boreholes were optimally placed in the middle of the seam at the lower end. The study provides a reference for self‐pressure‐relief gas drainage technology and optimization of borehole placement.

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Section: Model Assumptionsmentioning

confidence: 99%

Section: Deformation Field Control Equations For Gas-bearing Coal Rocksmentioning

confidence: 99%

“…The coal body's permeability is related to the development of its pore and fissure structure and the different stress states that can cause changes in the skeleton deformation and pore volume of the coal rock 19 . Therefore, the equation for the change in the stress field of gas‐bearing coal, taking into account the ground stress, the adsorption of a gas by coal–rock particles, and the change in gas pressure is 3,12,20