Numerical study on the mechanism of air leakage in drainage boreholes: A fully coupled gas-air flow model considering elastic-plastic deformation of coal and its validation

Wang, Kai; Wang, Long; Ju, Yang; Dong, Huzi; Zhao, Wei; Du, Changang; Guo, Yangyang; Lou, Zhen; Han, Gaorong

doi:10.1016/j.psep.2021.11.049

Cited by 14 publications

(5 citation statements)

References 47 publications

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“…After drilling in soft coal seams, the sealing section of the hole collapses, causing the sealing to fail and the stress concentration to become unstable, resulting in the rapid failure of the sealing drilling extraction effect. This not only blocks the passage of gas emissions and flow, seriously affecting the efficiency of gas extraction, but also increases the difficulty of sealing engineering [27,28]. From this, it can be seen that a reinforcement sealing technology that can stabilize the position of the borehole sealing section to prevent hole collapse and effectively support the stress concentration area of the sealing section to resist deformation is of great significance for improving the effectiveness of gas extraction in soft coal seam mines.…”

Section: Methodsmentioning

confidence: 99%

Expansion Characteristics and Creep Test of New Curing Expansion Material for Gas Extraction Boreholes

Jiang,

Bao,

Lei

2024

Processes

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In order to find the optimal expansion effect of a new curing expansion material so that it can better meet the requirements of the efficient sealing of drilled holes, the expansion and creep characteristics of the new curing expansion material were studied. Based on the creep results of graded loading, the Kelvin–Volgt model was selected to analyze its mechanical parameters, and a new “concentric ring” reinforcement sealing method was proposed. Numerical simulation was employed to analyze and discuss the reinforcement radius and depth of the “protective wall rock hole ring” in the “concentric ring” model, and on-site application experiments were carried out in a soft coal seam. The results show that the “concentric ring” reinforcement sealing method can effectively solve the problems of easy collapse and stress concentration instability in the sealing section of soft coal seams, ensuring long-term and efficient sealing of gas extraction boreholes in soft coal seams. When the diameter of the extraction drilling hole is 100 mm, the optimal reinforcement radius for the “protective wall rock hole ring” is 0.16–0.18 m. A reasonable reinforcement depth of the “protective wall rock hole ring” for drilling in soft coal seams is about 0.8–1 times the width of the roadway. In the on-site application process, experimental boreholes using “concentric ring” reinforcement sealing technology did not show any collapse phenomena, and the volume fraction of extracted gas remained above 30% for the first 30 days. Moreover, the gas volume fraction on the 30th and 60th days was 2.5 times and more than 3 times that of bag sealing boreholes using expanded cement, further proving that the sealing quality of boreholes using “concentric ring” reinforcement sealing is higher.

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Section: Methodsmentioning

confidence: 99%

Expansion Characteristics and Creep Test of New Curing Expansion Material for Gas Extraction Boreholes

Jiang,

Bao,

Lei

2024

Processes

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“… diffusion field governing equation: 1 governing equation of seepage field: 35 coal constitutive equation: 25 temperature field governing equation: 22 , 27 permeability model: …”

Section: Numerical Simulation Analysismentioning

confidence: 99%

Simulation Study of Coal Seam Gas Extraction Characteristics Based on Coal Permeability Evolution Model under Thermal Effect

Cao,

Jing,

Huo

et al. 2024

ACS Omega

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The permeability evolution law of high temperature and high stress coal seam is determined by the influence of multiphase coexistence and multifield coupling. In an environment greatly affected by disturbance and high temperature, the coal permeability model under the coupling of thermal and mechanical creep is not only a vital framework from which to examine gas migration law in multiphase and multifield coal seams but also an important theoretical foundation for gas control in coal seams. The influence of high-temperature environment on creep deformation and permeability is analyzed by several creep seepage tests under different temperature conditions.A mathematical model for the evolution of coal permeability considering the influence of temperature is established through the theory of matrix–crack interaction based on gas adsorption and desorption and thermal expansion deformation. Based on the permeability model under the coupling of thermal and mechanical creep, the numerical model of gas migration, seepage field, diffusion field, stress field, and temperature field is constructed, and the law of gas migration in coal seam under multifield coupling is explored. The influence law of thermal effect on gas extraction characteristics is analyzed, in which the time-varying mechanism of temperature field, the relationship between creep deformation and temperature and pressure, the influence of creep deformation on permeability, the dynamic distribution of gas pressure, and the change of gas extraction quantity are described in detail. It is concluded that the influence of temperature on permeability is much greater than that of creep deformation and that a high initial coal seam temperature is beneficial to gas extraction. It provides theoretical basis and technical guidance for the study of multifield coupled gas migration and coal seam gas treatment.

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“…The occurrence of gas in the coal seam and the behavior of high-pressure gas injection in the coal seam change the mechanical response of the coal body [36]. The change in coal automated response reacts to gas and affects gas migration in coal.…”

Section: Geomechanical Response Equation Of Coal Seammentioning

confidence: 99%

Numerical Simulation Study of High-Pressure Air Injection to Promote Gas Drainage

Zheng

Liu

et al. 2022

Sustainability

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Coal-accompanying gas is an essential resource, with numerous mining methods. The practice has proved that injecting high-pressure air into the coal seam can replace and flush the gas in the coal seam, effectively solving the problem of inadequate single gas drainage in soft and low permeability coal seams. This paper uses the finite element method to solve the model, simulate and study the gas drainage by high-pressure air injection in the bedding drilling, and establish a fluid-structure coupling model for gas drainage by high-pressure air injection. The competitive adsorption of N2, O2, and CH4, diffusion and migration of CH4 in coal matrix and fissure, matrix deformation caused by CH4 adsorption, and desorption and control of coal deformation by applied stress are considered in the model. When the fixed extraction time is 600 days (d), the optimal spacing between the extraction hole and injection hole is 12.5 m. The safe extraction effect and minimum drilling amount can be ensured. It provides a basis for guiding gas drainage by injecting high-pressure air on-site.

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Numerical study on the mechanism of air leakage in drainage boreholes: A fully coupled gas-air flow model considering elastic-plastic deformation of coal and its validation

Cited by 14 publications

References 47 publications

Expansion Characteristics and Creep Test of New Curing Expansion Material for Gas Extraction Boreholes

Expansion Characteristics and Creep Test of New Curing Expansion Material for Gas Extraction Boreholes

Simulation Study of Coal Seam Gas Extraction Characteristics Based on Coal Permeability Evolution Model under Thermal Effect

Numerical Simulation Study of High-Pressure Air Injection to Promote Gas Drainage

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