A New Cleat Volume Compressibility Determination Method and Corresponding Modification to Coal Permeability Model

Zeng, Quanshu; Wang, Zhiming

doi:10.1007/s11242-017-0906-0

Cited by 15 publications

(14 citation statements)

References 30 publications

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“…Afterward, on this basis, researchers proposed diverse theories including linear gas diffusion theory, seepage-diffusion theory, nonlinear gas flow, gas flow under the effect of a geophysical field, and gas leakage theory in multiple coal seams. The representative permeability models with a single borehole considering elastic deformation 28,29 include Seidle-Huitt, [30][31][32] Palmer-Mansoori, 33,34 Shi-Durucan, 35,36 Cui-Bustin, 37,38 and Robertson-Christiansen models. Based on the adsorption mechanism, numerous scholars have established different models such as the Langmuir model, 16,17 Brunauer-Emmett-Teller (BET) model, 18 Polanyi adsorption potential, [19][20][21][22] Langmuir-Freundlich adsorption model, 23,24 micropore filling theory, 25,26 and Freundlich Equation.…”

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confidence: 99%

“…At present, the permeability of coal seams is investigated mainly through permeability model with a single borehole for elastic deformation, permeability model with dual boreholes considering elastic deformation of coal blocks, etc. The representative permeability models with a single borehole considering elastic deformation 28,29 include Seidle-Huitt, [30][31][32] Palmer-Mansoori, 33,34 Shi-Durucan, 35,36 Cui-Bustin, 37,38 and Robertson-Christiansen models. [39][40][41] These models only explore the influence of pore pressure on permeability and porosity on the premise that the external stress remains constant.…”

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confidence: 99%

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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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confidence: 99%

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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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“…(44) is better able to capture the response of experimentally observed permeability data, as compared to Eq. (43) (e.g., Shi et al 2014;Zeng and Wang 2017). The reason for this is that η is generally restricted to three (to reflect the match stick model).…”

Section: Application Of the Shi And Durucan Modelmentioning

confidence: 99%

Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions

2019

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“…With respect to another factor, the sorption gas on the coal pore wall gradually desorbs with a decrease in reservoir pressure, causing matrix shrinkage strain, leading to an increase of the fracture width, and an increase in permeability of the coal . In the process of reservoir pressure reduction, coal permeability first decreases and then increases, accompanied by an obvious inflection point, that is, the rebound pressure point. , Therefore, an in-depth understanding of the influence of sorption expansion/contraction strain and effective stress on permeability is the foundation to formulating a feasible mining plan and, consequently, predicting CBM production …”

Section: Introductionmentioning

confidence: 99%

“…13,17 Therefore, an in-depth understanding of the influence of sorption expansion/contraction strain and effective stress on permeability is the foundation to formulating a feasible mining plan and, consequently, predicting CBM production. 18 To study the evolutionary law relating to coal permeability, the boundary conditions of CBM reservoirs can be simplified. During the continuous production of CBM, the overlying strata remain basically unchanged, and the horizontal boundary is fixed.…”

Section: Introductionmentioning

confidence: 99%

Impact of Sorption-Induced Strain and Effective Stress on the Evolution of Coal Permeability under Different Boundary Conditions

Yao

Gao

et al. 2021

Energy Fuels

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Coalbed methane (CBM) is a relatively common unconventional natural gas, which has great exploitation value. Coal permeability is an important parameter that affects the production and production efficiency of CBM, which is mainly controlled by the sorption expansion/contraction strain and effective stress. To study the seepage characteristics of coal in the process of CBM production, we have used CH4 and CO2 as test gases separately and conducted comparative seepage tests of different gases under constant pore pressure conditions. At the same time, the elastic modulus reduction coefficient R m has been introduced to characterize the sorption strain of coal, following which the permeability models suitable for different boundary conditions were derived according to the stress–strain relationship. Under the two gases, the new model could not only better reflect the law of coal sorption strain but also better reflect the relationship among effective stress, pore pressure, and coal permeability. Under the conditions of constant pore pressure, coal permeability was mainly controlled by effective stress; with the increase of effective stress, permeability decreased sharply initially and then gradually. Under the conditions of uniaxial strain and constant external stress, with an increase of pore pressure and R m, the matrix sorption expansion strain increased, resulting in a narrowing of the seepage channel, and R m indirectly inhibited permeability. At this point, coal permeability was mainly controlled by sorption expansion/contraction strain and effective stress. In addition, compared with other permeability models, the new permeability model possesses higher applicability both in theoretical mechanism and in data matching. The general change trend concerning coal permeability, determined by rebound pressure p rb, was consistent with the test results, which further verified the applicability of the model. It is believed that the results of this study could provide a basis for subsequent research on the stress–strain–permeability relationship and for the study of efficient development of CBM.

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A New Cleat Volume Compressibility Determination Method and Corresponding Modification to Coal Permeability Model

Cited by 15 publications

References 30 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

Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions

Impact of Sorption-Induced Strain and Effective Stress on the Evolution of Coal Permeability under Different Boundary Conditions

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