Gas seepage equation of deep mined coal seams and its application

Hu, Guozhong; Wang, Hongtu; Tan, Hai-xiang; Xiao-gang, Fan; Yuan, Zhigang

doi:10.1016/s1006-1266(08)60280-1

Cited by 20 publications

(16 citation statements)

References 9 publications

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“…Gas migration in coal seams is a complex process influenced by multiple factors while conforming to the law of conservation of mass. Accordingly, the equation of continuity for gas seepage 43 is shown in Equation (1).…”

Section: Governing Equation For Flow Field Of Gas In Boreholesmentioning

confidence: 99%

Numerical simulation of boreholes for gas extraction and effective range of gas extraction in soft coal seams

Pan

Huang

et al. 2019

Energy Science & Engineering

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Gas disasters are a major factor influencing safe production in mines: Gas extraction can reduce the gas content in coal seams, providing a guarantee of safer production. The parameters for gas extraction are the primary factors influencing the effectiveness thereof. Aiming at the creep properties of soft coal, a fluid‐solid coupling mathematical model considering creep properties of coal was established based on dynamic evolution equation for permeability considering the effects of matrix shrinkage and effective stress. Additionally, by utilizing COMSOL Multiphysics software, the gas extractions from a single borehole and multiple boreholes were calculated. Moreover, the parameters for gas extraction were optimized and applied and tested in field conditions. The result showed the reduction in gas pressure around the boreholes was larger than that from a single borehole when conducting gas extraction from multiple boreholes. The borehole spacing when extracting gas in coal seams by drilling multiple boreholes should be more than twice that of the effective drainage radius. The optimal borehole spacing ranged from 3.2 to 4.2 m for gas extraction lasting 180 d. Numerical simulation was carried out to ascertain the distribution of stress on coal around a roadway. The result revealed that the damage radius of the roadway was 11.8 m, and a reasonable hole‐sealing depth was 12 m. On condition that the borehole spacing during gas extraction from multiple boreholes was 4 m, the reasonable pre‐extraction time was 180 days taking the gas pressure being reduced to <0.74 MPa as a critical point. Furthermore, the gas content, the amount of extracted gas, etc, in a working face after the parameters for gas extraction were optimized were measured. The result suggested that the effect of gas extraction after optimizing parameters conformed to industry standards.

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Section: Governing Equation For Flow Field Of Gas In Boreholesmentioning

confidence: 99%

Numerical simulation of boreholes for gas extraction and effective range of gas extraction in soft coal seams

Pan

Huang

et al. 2019

Energy Science & Engineering

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“…where q is coal mass apparent density, g/cm 3 According to the basic definition of porosity, the dynamic evolution model of porosity is established under consideration of adsorption expansion, and pore compression and the effect of thermal expansion [15].…”

Section: Permeability Equationmentioning

confidence: 99%

“…The foundation for determining the permeability coefficient has been established by the proposed radial flow methods [1,3]. The borehole radial flow method has been widely used in our country owing to its precise measurement results, practicality and less limitations from the conditions of coal seam, although this test method is complicated.…”

Section: Introductionmentioning

confidence: 99%

A method of determining the permeability coefficient of coal seam based on the permeability of loaded coal

Wei

Wang

et al. 2014

International Journal of Mining Science and Technology

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“…2,3 The most effective way to reduce gas disasters is gas drainage. 4 Gas content, gas pressure, and permeability of coal seam directly determine the difficulty of gas drainage. 5 With the continuous increase of mining depth, in situ stress also increases, coupled with complex geological conditions, leading to further reduction of coal seam permeability and making it more difficult for gas drainage.…”

Section: Introductionmentioning

confidence: 99%

Methane Adsorption Influence and Diffusion Behavior of Coking Coal Macromolecules under Different Moisture Contents

et al. 2020

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To study the adsorption and diffusion behavior of methane on coal macromolecules under different moisture contents, the macromolecular model of coking coal was established through elemental analysis and 13 C NMR and X-ray photoelectron spectrum (XPS) experiments. Using this molecular model, the variation of methane adsorption capacity under five different moisture contents (0, 1.4, 2.3, 3.2, and 4.4%) was investigated. The effect of methane adsorption was explained from energy distribution and the radial distribution function (RDF). Finally, the diffusion behavior of methane on adsorption capacity was studied according to the diffusion coefficient. Simulation results indicate that absolute adsorption capacity and saturated adsorption capacity of methane decrease with the increase of moisture content. Compared with experimental results, the relative adsorption error of the saturated adsorption A is 7.49%; the curve trend of the simulation results is basically consistent with the experimental results, which conforms to the law of the Langmuir adsorption curve (type I). From the energy point of view, the methane molecular priority at the adsorption site is between −22 and −20 kJ/mol and the peak value is about −19.4 kJ/mol, which is not better than the adsorption position. Based on the heteroatoms in the model, the influence of the oxygen atom and the sulfur atom on methane adsorption is stronger than that of the nitrogen atom. Through the calculation of the diffusion coefficient, the diffusion coefficient decreases with the increase of the moisture content, which leads to the decrease of the absolute and saturated adsorption capacities. On the basis of this fact, the diffusion coefficient is found to directly affect the adsorption capacity and adsorption characteristics. This conclusion provides a valuable reference and a new way to study similar coal molecules.

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Gas seepage equation of deep mined coal seams and its application

Cited by 20 publications

References 9 publications

Numerical simulation of boreholes for gas extraction and effective range of gas extraction in soft coal seams

Numerical simulation of boreholes for gas extraction and effective range of gas extraction in soft coal seams

A method of determining the permeability coefficient of coal seam based on the permeability of loaded coal

Methane Adsorption Influence and Diffusion Behavior of Coking Coal Macromolecules under Different Moisture Contents

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