Parameter Optimization of Gas Extraction Borehole Layout Scheme:Take Baode Coal Mine as an Example
Aiming at the problems such as low preextraction concentration,large attenuation coefficient and long gas preextraction time,the No.8 coal seam of Baode coal mine was taken as the research object.Through the experimental analysis and field test of permeability anisotropy of No.8 coal seam,the optimal parameters of borehole layout and sealing process of No.8 coal seam were studied.The results show that the best drilling and extraction effect is obtained when the pre-pumping borehole is 90° with the coal wall fracture and the drilling angle is-6°.Using new material+bag as the sealing material,when the sealing distance is 8～16 m,increasing the pressure and"two plug two injection"grouting method can effectively provide the sealing air tightness.Through three different test methods,it is determined that the effective extraction radius of the drilling hole is about 4 m at 4 months and 4.5 m at 6 months.Based on this,the optimal layout parameters of gas extraction borehole in the working face were obtained.The research results provide a reference for the design of pre-extraction borehole in the working face of thick coal seam with high gas and low permeability.
gas drainagecoal seam permeabilitybedding drillingsealing processextraction radius
万方数据
维普
