The Experts below are selected from a list of 1698 Experts worldwide ranked by ideXlab platform
Fazhi Yan - One of the best experts on this subject based on the ideXlab platform.
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experimental study of Drainage Radius considering borehole interaction based on 3d monitoring of gas pressure in coal
Fuel, 2019Co-Authors: Chaolin Zhang, Shoujian Peng, Fazhi YanAbstract:Abstract In practical engineering, borehole Drainage is the most effective and widely used method of extracting coalbed methane (CBM). The Drainage Radius of a borehole is a key parameter in determining the design and layout of Drainage boreholes, and the interaction among boreholes in multiple-borehole system significantly influences the Drainage Radius of each individual borehole. Therefore, the physical simulation experiments of gas Drainage with single, double, and multiple boreholes were carried out using a self-developed device. This paper discusses the Drainage Radius considering borehole interaction based on 3D monitoring of gas pressure in coal, which can provide reference data for numerical simulation and offer practical guidance for engineering. The results show that multiple boreholes lead to a faster drop in gas pressure along the monitoring line and require less time to reach the safety line, with two distinct propagation patterns observed in the effective Drainage zones. Besides, a calculation model was proposed for obtaining the Drainage Radius of a borehole. The Drainage Radius can be fitted using a power function with respect to Drainage time, with larger values giving an increase in the Drainage Radius. Meanwhile, a benchmark borehole was selected from which the gas pressure decrease coefficients at different monitoring points are calculated; these coefficients reflect the degree of borehole interaction. The relationship between the pressure decrease coefficient and Drainage time is approximated by a negative exponential function, with multiple boreholes exhibiting more intense interaction. Finally, it is found that the influence of other boreholes on monitoring points near the reference borehole is relatively small and subject to a time lag.
Lianhua Cheng - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of influence of langmuir adsorption constant on gas Drainage Radius of drilling in coal seam
International journal of mining science and technology, 2016Co-Authors: Haifei Lin, Meng Huang, Chao Zhang, Lianhua ChengAbstract:Abstract To determine reasonable distance of gas pre-Drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants, the paper conducted the numerical simulation of pre-Drainage gas in drillings along coal seam, studied the relationship of adsorption constants and permeability, gas pressure, and effective Drainage Radius of coal seams, and applied the approach to the layout of pre-Drainage gas drillings in coal seams. The results show that the permeability of coal seams is on the gradual increase with time, which is divided into three sections according to the increase rate: the Drainage time 0–30 d is the sharp increase section; 30–220 d is the gradual increase section; and the time above 200 d is the stable section. The permeability of coal seams is in negative linear and positive exponent relation with volume adsorption constant V L and pressure adsorption constant P L , respectively. The effective Drainage Radius is in negative linear relation with V L and in positive exponent relation with P L . Compared with the former design scheme, the engineering quantity of drilling could be reduced by 25%.
Chaolin Zhang - One of the best experts on this subject based on the ideXlab platform.
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experimental study of Drainage Radius considering borehole interaction based on 3d monitoring of gas pressure in coal
Fuel, 2019Co-Authors: Chaolin Zhang, Shoujian Peng, Fazhi YanAbstract:Abstract In practical engineering, borehole Drainage is the most effective and widely used method of extracting coalbed methane (CBM). The Drainage Radius of a borehole is a key parameter in determining the design and layout of Drainage boreholes, and the interaction among boreholes in multiple-borehole system significantly influences the Drainage Radius of each individual borehole. Therefore, the physical simulation experiments of gas Drainage with single, double, and multiple boreholes were carried out using a self-developed device. This paper discusses the Drainage Radius considering borehole interaction based on 3D monitoring of gas pressure in coal, which can provide reference data for numerical simulation and offer practical guidance for engineering. The results show that multiple boreholes lead to a faster drop in gas pressure along the monitoring line and require less time to reach the safety line, with two distinct propagation patterns observed in the effective Drainage zones. Besides, a calculation model was proposed for obtaining the Drainage Radius of a borehole. The Drainage Radius can be fitted using a power function with respect to Drainage time, with larger values giving an increase in the Drainage Radius. Meanwhile, a benchmark borehole was selected from which the gas pressure decrease coefficients at different monitoring points are calculated; these coefficients reflect the degree of borehole interaction. The relationship between the pressure decrease coefficient and Drainage time is approximated by a negative exponential function, with multiple boreholes exhibiting more intense interaction. Finally, it is found that the influence of other boreholes on monitoring points near the reference borehole is relatively small and subject to a time lag.
L I Xijian - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of gas Drainage Radius and its influencing factors in coal seam
Industrial Safety and Environmental Protection, 2012Co-Authors: L I XijianAbstract:Gas Drainage Radius in coal seam is an important basis to choose the Drainage methods,determine the parameters of drilling layout and evaluate the Drainage effect.In order to determine the effective Drainage Radius and find out its influencing factors,the numerical simulation method is used and the computational fluid dynamics software Fluent is applied to establish the model of gas Drainage.The gas flowing law in Drainage is simulated by using the Darcy law,the effective Drainage Radius is determined,and the effects of drilling diameter,the permeability of coal seam and Drainage negative pressure on it is analyzed.The results show that the effective gas Drainage Radius is about 1.8 m,the impact of drilling diameter and the permeability on Drainage Radius is relatively large and the Drainage negative pressure has little effect.
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gas Drainage Radius determination of faer coal mine
Coal Technology, 2012Co-Authors: L I XijianAbstract:In order to improve gas Drainage effect of Drainage holes,according to site testing in Faer Coal Mine,by observing the gas pressure of the gas pressure hole at different distances from the crossing holes,the gas pressure index and gas Drainage efficiency are analyzed by gray correlation analysis method,effective gas Drainage Radius of 7# coal seam are ultimately determined.The result provides certain theoretical basis for gas Drainage at the outburst working face before mining.
Sun Lijuan - One of the best experts on this subject based on the ideXlab platform.
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determination method of gas Drainage Radius based on multi physics coupling
Journal of China Coal Society, 2013Co-Authors: Sun LijuanAbstract:In order to determine reasonable gas Drainage Radius,the hydro-mechanical coupling model considering rheological properties,permeability dynamics and the adsorption characteristics had been developed in this study.Therefore,the borehole aperture variations of hard and soft coal seam were comparatively analyzed,the dynamic evolution of penetration was studied,the effective gas Drainage Radius in hard and soft coal seams were determined,and the main influence factors of gas Drainage Radius were found.The results show that:shrinkage phenomenon of borehole in hard and soft coal seam occurs over time because of rheological properties,the borehole in soft seam will be blocked in a short time,although the borehole diameter in hard coal seams reduces,but borehole is still in stable condition,the gas Drainage channel is not blocked.It is necessary to analyze borehole aperture variation and determine effective Drainage time before determining gas Drainage Radius.Coal permeability during gas Drainage is gradually increasing over time.The main influence factors of gas Drainage Radius is:coal hardness,burial depth,initial gas pressure,initial permeability and hole diameter.
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study on comparison of methods to determine gas Drainage Radius and existed problems
Coal science and technology, 2012Co-Authors: Sun LijuanAbstract:In order to rapidly and effectively eliminate the outburst danger of the mining and excavation faces,the paper stated each method to determine the gas Drainage Radius,pointed out the problems existed in the determination of the gas Drainage Radius and had an outlook on the further study to determine the gas Drainage Radius.The study results showed that the gas Drainage Radius measures at site had high measuring difficulty and poor accuracy.The measured results were only the interval value and other problems.The gas Drainage Radius measured could not be dynamically varied with the gas geological conditions.The gas Drainage Radius determined with the numerical simulation method had not considered the rheology features of the gas content coal and the effective gas Drainage time determined had a high error.A further study on the liquid and solid coupling during the Drainage process should consider the rheology features of the gas content coal to determine the rational gas Drainage Radius and to provide the basis for the gas disaster prevention and control.
