Study On Gas Extraction Technology Of Cis Layer Drilling In 11-2 Coal Seam Of Pan San Mine

Mine gas disaster is the biggest threat to China's current mine safety production.Gas itself is a kind of clean energy with high heat energy.It should not only prevent gas to bring serious disaster to mine,but also avoid the waste of such energy.The most effective means is gas extraction.This paper collects and collects the basic situation of 11-2 Coal seam.Secondly,through the field test,it is concluded that the basic gas parameters of the test coal seam are as follows:the absolute gas pressure of the 11-2 Coal Seam 17102(1)is 1.2MPa,the coal seam gas content is 7.4m3/t,the coal seam permeability coefficient is 0.028m2 · MPa-2 · d-1.Using the coal seam gas content reduction method to test the effective gas extraction radius of the coal seam in 11-2 Coal Seam,the gas pressure and gas content of the coal seam at different distance from the different distance extraction boreholes are measured and analyzed.Through the comparison of the parameters at different distance,the gas in the 11-2 Coal seam of Pan three coal mine after the continuous extraction of 30d The effective extraction radius is 5m,and the hole length of three groups with different length is selected at 1662(1).The length of the sealing hole is 20m,18m and 15m respectively.Through the comparison and analysis of the concentration and the extraction purity of the three sets of test drilling time,the sealing length of the bedding hole in the 11-2 Coal Seam of the pan three coal mine should be obtained.More than 18m is appropriate,and through statistical analysis of the historical drilling data of 17161(1)working face and 17181(1)face borehole drilling,it is obtained that the gas extraction effect is best when the size of suction pressure is in the 30?35kPa interval.The outer side of the 1662(1)lane is selected as the site of the test to verify the effect of the pipe.By comparing the gas content of the drill hole under the corresponding extraction time and the depth of the drill hole,the gas concentration distribution map around the drilling hole is drawn.It is concluded that the whole course protection pipe is beneficial to the gas extraction,and the role of the lower pipe is more obvious with the effect of time.Based on the calculation and analysis of key parameters such as residual gas content,residual pressure,analytical volume and total extraction rate after 11-2 Coal Seam Extraction,the calculation results show that the effect of gas drainage on 11-2 seam bedding holes meets the relevant regulations,and has good gas drainage effect.