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

Ji, Ming; Sun, Zhongguang; Sun, Wei

doi:10.1155/2021/5510566

Cited by 6 publications

(6 citation statements)

References 14 publications

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“…To better study the change in gas pressure in the borehole, a two-dimensional reference plane was intercepted on the cross-section YZ with X as the 30 m coordinate, and the yellow arrows in Figure 5 correspond to the transformation relationship between the two-dimensional cross-section and the three-dimensional model. The parameters used in the numerical simulation are mainly from field engineering measurements and refer to some quantitative research papers [31][32][33][34], as shown in Table 2.…”

Section: Numerical Model and Parametersmentioning

confidence: 99%

“…According to the "Basic Indicators of Gas Extraction in Coal Mines", the area where the gas pressure around the borehole is less than 0.74 MPa within a certain extraction time is the extraction standardized area [6,35,36]. It can be seen from Figure 6 measurements and refer to some quantitative research papers [31][32][33][34], as shown in Table 2…”

Section: Effective Radius Of Gas Extraction For Extraction Cyclementioning

confidence: 99%

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Optimization of Accurate Spacing for Gas Extraction from Damaged Coal Seams Based on a Dual-Penetration Model

Yan,

Lei,

Jiang

et al. 2023

Sustainability

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In order to develop precise hole placement technology for gas extraction, this paper combines industrial testing, the evolution law of coal rock damage permeability, and the coal double-pore double-permeability model; establishes a coupling model of the coal damage deformation field and matrix-fracture double diffusion seepage field; and determines precise hole placement spacing for a coal seam gas by using the COMSOL Multiphysics 5.6 numerical simulation software. This study shows that the effective radius of gas extraction is 4.8 m after 180 d of extraction, which is a power function of the extraction time. The permeability of the coal body is affected by matrix adsorption, and contraction and effective stress, and the influence range between the boreholes under multi-hole extraction increases with the increase in spacing; at the same time, we took into account the positive effect of the permeability change on the extraction effect and ultimately determined the optimal spacing of boreholes in Dashucun Mine to be 6 m, which was arranged in the square area. The extraction effect was good after the on-site test, and the results of this study can provide guidance for the optimal arrangement of the spacing of boreholes in the underground areas of coal mines.

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Section: Numerical Model and Parametersmentioning

confidence: 99%

Section: Effective Radius Of Gas Extraction For Extraction Cyclementioning

confidence: 99%

Optimization of Accurate Spacing for Gas Extraction from Damaged Coal Seams Based on a Dual-Penetration Model

Yan,

Lei,

Jiang

et al. 2023

Sustainability

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“…Both adsorbed and free gas are present in the pore system of the coal matrix [33], and the gas content of the matrix system, mm, is as follows:…”

Section: Matrix Pore Gas Diffusion Equationmentioning

confidence: 99%

“…where ρ c is the pseudo-density of the coal body, kg/m 3 ; M c is the molar mass of methane, kg/mol; R is the gas constant, J/(mol•K); T is the temperature of the coal seam, K; and V M is the molar volume of the gas at standard conditions, L/mol. The equilibrium state of the coal bed matrix system and the fissure system is broken under the action of the pressure difference, and the diffusion of adsorbed gas in the matrix provides a mass source for the fissure gas transport due to the different velocities of matrix diffusion and fissure seepage [33], which can be obtained from the mass conservation theorem:…”

Section: Matrix Pore Gas Diffusion Equationmentioning

confidence: 99%

Simulation Study on the Characteristics of Gas Extraction from Coal Seams Based on the Superposition Effect and Hole Placement Method

Jin

Zhang

et al. 2023

Sustainability

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In order to obtain a reasonable extraction drilling method for coal seam working faces and to carry out targeted as well as cost-effective hole placement optimization, a gas–solid coupled model based on the coal rock deformation field and the matrix–fissure dual seepage–diffusion field was established and numerically solved via the use of COMSOL Multiphysics finite element software to optimize the gas transport parameters of the Dongpang coal mine based on the study of the coal seam gas transport law. This study shows the following: With an increase in the extraction time, the gas content of the coal seam was reduced to a minimum. It shows that, with an increase in the extraction time, the gas pressure and seepage velocity keep decreasing the stable value, the main stress around the borehole redistributes, and the coal permeability keeps decreasing with an increase in the decay coefficient. The extraction radius of the boreholes increases exponentially with the extraction time, and the reasonable extraction hole size is 94 mm; the use of multiple boreholes for pre-drawing gas via the use of the interval between the effective extraction radius and the influence radius results in a blind extraction zone caused by the superposition effect between the boreholes, and the residual gas value of the coal seam increases with an increase in the borehole spacing. The use of an equilateral triangular hole layout can avoid the extraction blind zone, and the pre-sumping effect is good after field application, which ensures the safe production of coal mines as well as the reasonable use of resources.

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“…(1) Reasonable Borehole Spacing in a Fully Pressure-Relief Zone. To determine reasonable borehole spacing in the fully pressure-relief zone (see Figure 10), according to the literature [24], five cases of gas extraction with borehole spacing being 20 m, 25 m, 30 m, 35 m, and 40 m are simulated, respectively. The gas pressure-time curves for monitoring point under varying borehole spacings are given in Figure 20.…”

Section: Reasonable Borehole Spacing In Different Pressure Relief Zonesmentioning

confidence: 99%

Numerical Assessment on Unloading Disturbance and Gas Extraction in Remote Distance Protective Layer Mining

et al. 2022

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Protective layer mining could not only significantly alter geostress but also increase the permeability of protected layer, which is beneficial for the coal gas extraction rate and ensures coal mining safety. However, due to unique geologic conditions, remote distance protective layer mining has its own characteristics. To investigate characteristic changes caused by remote distance protective layer mining, a suitable mathematical model that considered disturbance of unloading mining and solid-gas coupling effects during gas extraction was developed. The established mathematical model was implemented by combining FLAC3D and COMSOL programs to study characteristic changes during remote distance protective layer mining of Chajiaotan coal mine. Numerical simulation results of unloading disturbance mining indicated that the protected layer would experience a process of stress loading, stress unloading, stress recovery, and stress stability as the working face of protective layer advanced; unloading disturbance has a greater influence on coal permeability than gas pressure; gas extraction measure should be further adopted to decrease gas pressure. Numerical comparisons of gas pressure distribution in the original protected layer and unloading protected layer revealed that gas extraction after unloading disturbance can reduce gas pressure more effectively, and appropriate borehole spacings in the fully pressure-relief and nonfully pressure-relief zones are 30 m and 5 m, respectively. The layout of field boreholes for gas extraction was designed according to numerical results. The results of site investigation showed that numerical simulation results of relative expansion deformation and gas extraction radii agree well with the results of site observation, demonstrating reliability of the mathematical model and its implementation. The proposed mathematical model is promising for assessing unloading disturbance and gas extraction in remote distance protective layer mining.

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

Cited by 6 publications

References 14 publications

Optimization of Accurate Spacing for Gas Extraction from Damaged Coal Seams Based on a Dual-Penetration Model

Optimization of Accurate Spacing for Gas Extraction from Damaged Coal Seams Based on a Dual-Penetration Model

Simulation Study on the Characteristics of Gas Extraction from Coal Seams Based on the Superposition Effect and Hole Placement Method

Numerical Assessment on Unloading Disturbance and Gas Extraction in Remote Distance Protective Layer Mining

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