Analysis of Effective Radius of Coal Seam Gas Extraction
Aiming at the problems of the extraction effective radius for pre gas extraction cannot be accurately determined and others in the 3#coal seam of Rundong Coal Industry,through using methods of theoretical analysis and numerical simulation,the influencing factors of the extraction effective radius are analyzed.The results show that the controllable influencing factors of the extraction effective radius mainly include extraction time,extraction negative pressure,and extraction borehole hole diameter.The comparative analysis shows that there is a positive correlation between extraction time,borehole hole diameter,and effective radius,expressed as R=AtB,and the impact of extraction negative pressure on effective radius is not significant.The reliability of numerical simulation is verified through on-site monitoring,further confirmation is made that when the diameter of the designed gas borehole in the 3#coal seam of Rundong Coal Industry is 108 mm,the effective radii for pre extraction gas during the three time periods of 30 d,60 d,and 90 d are 1.4 m,2.2 m and 3.0 m,respectively.This provides a reference role for the borehole layout of pre extraction gas on site.
gas extractionextraction radiusnumerical simulationtheoretical calculation
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