Prediction of gas emission zone width in laneway’s coal seam based on slippage effect of gas seepage

2020 ◽  
pp. 1-17 ◽  
Author(s):  
Xiaohua Li ◽  
Hongmin Yang
Keyword(s):  
Coal Seam ◽  
Gas Emission ◽  
Zone Width ◽  
Slippage Effect ◽  
Gas Seepage

scholarly journals A Gas Seepage Modeling Study for Mitigating Gas Accumulation Risk in Upper Protective Coal Seam Mining Process

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Cun Zhang ◽  
Lei Zhang ◽  
Mingxue Li ◽  
Chen Wang
Keyword(s):  
Coal Seam ◽  
Field Measurements ◽  
Interlayer Spacing ◽  
Mitigation Measures ◽  
Plastic State ◽  
Geological Condition ◽  
Gas Emission ◽  
Working Face ◽  
Gas Seepage ◽  
Seam Mining

Protective coal seam mining (PCSM) is one of the most significant mitigation measures of regional outburst in the process of deep coal seam mining, which has high outburst risk in China. During the PCSM process, the phenomenon of methane concentration exceeding the limit usually occurs in the working face. It is vital to understand factors affecting gas emission from the protective seam working face (PSWF) and to obtain an equation for determining the quantity of gas emission. A gas seepage model (GSM) was developed to simulate the gas emission during the process of upper PCSM. In this study, an equation was formulated to determine the quantity of gas desorbed from the protected seam into PSWF. These equations have been developed by using Fick’s second law of diffusion and Darcy’s flow law. The relationship between permeability and stress was described in an elastic-plastic state, and the mechanics of surrounding rock were investigated. It can be concluded from GSM that the initial gas pressure of protected seam, the characteristics of interlayer rocks, and the ventilation pressure of PSWF were the main factors that influenced the desorption of gas emission from the protected seam into PSWF. The developed GSM was tested for calculating gas emission quantity from the PCSM process by utilizing the actual geological condition data of a coal mine, which is located in Hancheng, China. The results have shown great agreement with obtained field measurements, which is done by combining the fitting curve of ventilation air methane quantity for PSWF with an interlayer spacing. A loss coefficient (δ) of 1.012 × 10−3 was obtained in this study.

A Simulative Method on Gas Seepage in Coal Seam around Borehole

2013 ◽  
Vol 353-356 ◽  
pp. 3176-3181 ◽  
Author(s):  
Guo Qiang Cheng ◽  
Yi Wang
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Thermal Conduction ◽  
Emission Rate ◽  
Early Stage ◽  
Simulation Method ◽  
Actual Situation ◽  
Gas Emission ◽  
Gas Seepage ◽  
Theoretical Results

Based on the analogy between equations of gas seepage in coal seam and that of thermal conduction, a simulative method on gas seepage in coal seam was proposed through that thermal conduction interpreted as gas seepage. The laws of gas emission from borehole in homogeneous and heterogeneous coal seam were analyzed using this method. It indicates that the simulative results of the gas emission from borehole in homogeneous coal seam were satisfied with the corresponding theoretical results during the early stage of gas seepage, while a tolerance between the numerical results and the theoretical ones was appeared in the later period. This is due to the simplification as solving the theoretical equations. The results of heterogeneous coal seam show that curves of gas emission rate conform to the actual situation. The numerical simulation method on the law of gas emission from borehole in coal seam is feasible.

Computational fluid dynamics optimization of gas drainage technology in gas-mining areas

2021 ◽  
pp. 014459872110635
Author(s):  
Wei Zhao ◽  
Wei Qin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Coal Seam ◽  
Field Tests ◽  
Mining Area ◽  
Engineering Practice ◽  
Horizontal Distance ◽  
Gas Drainage ◽  
Working Face ◽  
Gas Seepage

Coal mining results in strata movement and surrounding rock failure. Eventually, manual mining space will be occupied by the destructed coal rock, making it difficult to conduct field tests of the coal seam to explore gas seepage and transport patterns. Therefore, computational fluid dynamics (CFD) numerical computation is an important tool for such studies. From the aspect of gas pre-drainage, for layer-through boreholes in the floor roadway of the 8,406 working face in Yangquan Mine 5 in China, reasonable layout parameters were obtained by CFD optimization. For effectively controlling the scope of boreholes along coal seam 9 in the Kaiyuan Mine, CFD computation was performed. The results revealed that the horizontal spacing between boreholes should be ≤2 m when a tri-quincuncial borehole layout is used. Optimization of the surface well position layout for the fault structure zone in the Xinjing Mine of the Yangquan mining area indicated that the horizontal distance between the surface well and the fault plane should be <150 m. From the aspect of gas drainage with mining-induced pressure relief, CFD computation was performed for pressure-relieved gas transport in the K8205 working face of Yangquan Mine 3. The results showed that forced roof caving should be used before the overhang length of hard roof reaches 25 m in the K8205 working face to avoid gas overrun. From the aspect of gas drainage from the abandoned gob, surface well control scopes at different surface well positions were computed, and an O-ring fissure zone is proposed as a reasonable scope for the surface well layout. CFD computation has been widely applied to coal and gas co-extraction in the Yangquan mining area and has played a significant role in guiding related gas drainage engineering practice.

Determining the dimensions of the wetted zone of a coal seam from control-borehole gas emission

1969 ◽  
Vol 5 (6) ◽  
pp. 711-715
Author(s):  
V. N. Puzyrev ◽  
V. G. Meshcheryakov ◽  
A. T. Gorbachev
Keyword(s):  
Coal Seam ◽  
Gas Emission

Transformation of the Triaxial Seepage Device for Measuring Deformation of Coal Containing Gas

2013 ◽  
Vol 477-478 ◽  
pp. 610-613
Author(s):  
Mei Yuan ◽  
Qing Hao Meng ◽  
Jiang Xu ◽  
Bo Bo Li ◽  
Yu Qin Du
Keyword(s):  
Coal Seam ◽  
Gas Migration ◽  
Coal Deformation ◽  
Gas Seepage

To explore the regularity of deformation and gas migration of coal seam, the author transmits signal of strain foil on coal samples in all directions by transforming oil plug, oil plug seal, heat shrink tubing and wire seal, based on the existing triaxial seepage device. We can complete coal deformation and gas seepage test with this device under different temperature, different stress, different gas stress and so on.

scholarly journals Model of Prediction of Gas Emission based on Gas Content Uncertainty in Coal Mine using Geostatistical Simulation and Monte Carlo Method

2021 ◽  
Author(s):  
Shokofe Rahimi ◽  
Majid Ataee-pour ◽  
Hasan Madani
Keyword(s):  
Monte Carlo ◽  
Coal Seam ◽  
Ventilation System ◽  
Prediction Method ◽  
Simulation Method ◽  
Worker Safety ◽  
Gas Content ◽  
Geostatistical Simulation ◽  
Gas Emission ◽  
Factors Affecting

Abstract It is very difficult to predict the emission of coal gas before the extraction, because it depends on various geological, geographical and operational factors. Gas content is a very important parameter for assessing gas emission in the coal seam during and after the extraction. Large amounts of gas released during the mining cause concern about adequate airflow for the ventilation and worker safety. Hence, the performance of the ventilation system is very important in an underground mine. In this paper, the gas content uncertainty in a coal seam is first investigated using the central data of 64 exploratory boreholes. After identifying the important coal seams in terms of gas emission, the variogram modeling for gas content was performed to define the distribution. Consecutive simulations were run for the random evaluation of gas content. Then, a method was proposed to predict gas emission based on the Monte Carlo random simulation method. In order to improve the reliability and precision of gas emission prediction, various factors affecting the gas emission were investigated and the main factors determining the gas emission were identified based on a sensitivity analysis on the mine data. This method produced relative and average errors of 2% and 0.57%, respectively. The results showed that the proposed model is accurate enough to determine the amount of emitted gas and ventilation. In addition, the predicted value was basically consistent with the actual value and the gas emission prediction method based on the uncertainty theory is reliable.

scholarly journals The research of coal seam gas pressure and initial gas emission characteristics of borehole

2019 ◽  
Vol 7 (5) ◽  
pp. 1961-1969 ◽  
Author(s):  
Jianhua Zeng ◽  
Shixiang Tian ◽  
Guiyi Wu ◽  
Yunjun Zuo ◽  
Shiqing Xu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Gas Pressure ◽  
Emission Characteristics ◽  
Coal Seam Gas ◽  
Gas Emission

scholarly journals Prediction Model of Failure Zone in Roadway Sidewall considering the Lithologic Effect of Rock Formation

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Zenghui Zhao ◽  
Qing Ma ◽  
Shaojie Chen ◽  
He Ma ◽  
Xiaojie Gao
Keyword(s):  
Stress Distribution ◽  
Coal Seam ◽  
Coupling Effect ◽  
Limit Equilibrium ◽  
Pressure Coefficient ◽  
Variable Parameter ◽  
Western China ◽  
Analysis Model ◽  
Zone Width ◽  
Rock Formation

Coal seam damage area and its stress distribution law in roadway with medium thickness or extrathick coal seam are important issues for understanding the instability mechanism of roadway surrounding rock in weakly cemented soft rock strata in western China. Firstly, a variable parameter microelement analysis model is established based on the assumption of a plane stress integrating with the coal seam-rock’s interface and the rock formation on both sides; moreover, a formula is established by the strain compatibility relationship to express the state of stress in rock bodies on both sides of the interface. Then, a method for calculating the stress limit equilibrium zone width of the coal side and regional stress distribution is presented, which considers the coupling effect of the coal side-rock formation and is based on the loose medium limit equilibrium theory. Finally, the validity of the model is verified through a comparison with previous research and by being applied to an engineering example. The results show the following: (1) the interface adhesion effect results in an abrupt change of the stress state of both the rock formation and coal seam and is related to their deformation parameters; i.e., there is a coupling effect; (2) the limit equilibrium zone width is not only related to the buried depth of the roadway, excavated coal seam thickness, coal seam strength parameters, stress concentration factor, lateral pressure coefficient, and supporting strength of the side of the roadway, but it also has an effect on the aforementioned coupling effect; (3) due to the roof-coal seam-floor comprehensive structural effect, the model presented in this paper is applicable to both the coal seam failure and the failure along the coal seam-rock’s interface.

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