The Theory And Technology Study On Pressure Relief And Permeability Enhancements Of The Coal Seam With High Concentration Of Gas And Low Permeability

Coal is the basic energy in our country, and gas has been to the main factor which serious threatens the safety in production as the increase of mining depth. in our country, most of the coalfield hold low permeability coal seam, so the actual effect isn't perfect if take drainage borehole as the main technology. Therefore, enlarging the influence extent of one single drilling by pressure relief and permeability enhancements has been to the key segment for the sustainable development of the mine.Beginning as the research of the pores and fissures'microcosmic structure in the coal with different hardness, the thesis compares the fractal dimensions of the pore structure to the fissure structure and finds that both change to be less and less complex as the development of the coal's hardness.Then, the author sets up two simplified models to describe the situation of the gas flowing in the fissures: the capillary and the wall laminar flowing model. Then derive the motion equations and the analysis of the flow velocities and the flow rates in the two models based upon the interrelated conjecture and Darcy law and Fick's diffusion law.Thirdly, the thesis analyzes the gas flowing discipline in the coal around the drilling and obtains the overall gas rush perishing time. Moreover, the author finds that the main differences between the two models is the coefficients which is outlying with the time and the displacement, so just choose the capillary model when analyzing the effect of hydraulic slotting, obtains the overall gas rush perishing time as well in order to guide engineering practice.Fourthly, set up the experiment system and simulate the application effect of the technology of the High-Pressure Jet of Abrasive Drilling Slotting integration Outburst Prevention by replacing slot with melting paraffin board. from the data analysis, the author finds that the pressure relief range change larger as the increase of the slotting width while in the vertical direction, the extent of the pressure relief change smaller as the increase of the distance with the slot. in addition, the influencing range and extent is increasing in the upward coal seam, draw the pressure relief outline from the experiment results of two sides. Moreover, analyze the discipline of the ventilation property by the self-regulated testing ball, obtain the valid pressure relief range. Obtain the empirical equation that describes the relationship between the lower displacement and the distance after the 9mm slot formed as well. Meanwhile, the author sets up numerical calculation model, research the pressure relief effect of hydraulic slotting by FLAC. Firstly, analyze the pressure relief effect of drilling and slotting and find that the pressure relief effect of drilling is behind slotting obviously at the same stress conditions and mechanics parameters. The thesis studies the influencing factors of the pressure relief by two dimension simulation. Simulate the pressure relief effect of one single slot and multi-slots by FLAC 3D as well. in addition, the thesis simulates the effects of the bed-parallel drilling and single row transverse drilling and multi-row transverse drilling and finds that the two drilling styles are both successful. Especially, the latter can increase the overall permeability which is a nice foundation for per-vacuuming gas in large areas.Finally, develop the High-Pressure Jet of Abrasive Drilling Slotting integration Outburst Prevention equipment. The author popularizes the technology to the II8210 working face in Lu ling and the K4-K2 coal seam of the main coal of the No.1 coal in Yan Jing , evaluates and analyzes the interrelated parameters as well.From the research above, obtain the the overall gas rush perishing time in the pressure relief range by hydraulic slotting, while develop the drilling-slotting-pumping trinitarian technology which can be used to relieve pressure and enhance permeability of the coal with high concentration of gas and low permeability. Meanwhile, develop the High-Pressure Jet of Abrasive Drilling Slotting integration Outburst Prevention equipment, the everyday pumping net measure can increase 11 times by transverse drilling.