Numerical simulation and on-site application of effective extraction radius for mechanical reaming
In order to study the pressure relief and permeability enhancement effect of mechanical reaming at the driving face,the effective influence radius of driving after reaming was taken as the investigation index,and the mechanical reaming model was established with the help of COMSOL-Multiphysics numerical simulation software,and the gas flow field after mechanical reaming was dynamically analyzed,and the relationship curves between the effective influence radius of reaming and the extraction time was fitted.Through theoretical analy-sis and field investigation test,the pre-extraction effect of mechanical drilling and ordinary drilling under the same working conditions was compared,and the attenuation coefficient of gas flow under the conditions of the two construction processes was quantitatively discussed.Research has shown that the average gas extraction flow of mechanical reaming was 0.022 2 m3/min,and the lowest gas extraction flow was 56.9％of the initial extraction flow,with a decrease of 43.1％.The average gas extraction flow of ordinary boreholes was 0.006 826 m3/min,and the lowest gas extraction flow was 22.6％of the initial extraction flow,a decrease of 77.4％.The concentration of mechanical reaming decreased from 72％to 38％,a decrease of 47.2％,and the concentration of ordinary borehole extraction decreased from 39％to 17％,a decrease of 56.4％.It shows that the mechanical reaming pressure relief and penetration enhancement effect is remarkable.
mechanical reamingnumerical simulationeffective extraction radiusattenuation factorpressure relief and penetration
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