Application of permeability improving technology combined with hydraulic pressure fracturing and hydraulic slotting

According to the poor seam permeability,serious borehole collapsing,low concentration of the gas drainage and problems of the high tectonic stress area in Fengchun Mine of Chongqing Songzao Company,during the gas pre- drainage period,the permeability improving technology combined with hydraulic pressure fracturing an d hydraulic slotting was applied,the permeability improving principle of the hydraulic pressure fracturing and hydraulic slotting technology was analyzed and the comparison tests of the technology were conducted in No.- 2 Block drilling site of the air returning gateway in No. + 680N11203 coal mining face of Zhangshiba Mining Block. The resul ts showed that in comparison with the hydraulic pressure fracturing technology,hydraulic slotting technology and conventional borehole gas drainage technology,the perme ability improving technology combined with the hydraulic pressure fracturing and hydraulic slotting could obviously improve the permeability of the seam and improve the g as drainage concentration and the gas drainage effect. The volume fraction of the first gas drainage was 28% ~ 62% and was 8% ~ 13%,12% ~ 20% and 18% ~ 36% times higher than other three plans individually. The total volume fraction of the gas drainage was 36% and was 1. 33,1. 8 and 5.1 times higher than other three plans individuall y. The permeability improving technology combined with the hydraulic pressure fracturing and hydraulic slotting could keep a long time of the high efficient gas drainage. Af ter 28 days of gas drainage operation, the accumulated volume of the gas drainage was 7 908 m3 and was 1. 5,1.7 and 7 times higher than other three plans individually. T he total concentration of the gas drainage in the drilling site was not in an attenuation tendency basically and could be kept at about 36%.