Gas control technology in super large area of high gassy mine

Based on the development of high-power directional drilling technology and equipment and the improvement of mine gas prevention technology, BaodeCoal Mine has successively created the record of gas extraction in 2 311, 2 570 and 3 353 m underground directional long borehole, which provides the basic conditions for the implementation of gas control technology in super large area.Taking No.8 coal seam gas prevention and control in Baode coal mine as the research object, based on the needs of gas management in the area of ultra-long working face, according to the difference of regional scope and pre-draining time, the combined extraction of the well and the pre-drainage of the large area are adopted respectively. Measures such as large-area pre-drainage of pinnate boreholes in the heading face and large-area progressive pre-drainage of coal mining face have carried out large-area advanced pre-drainage of the coalbed methane in the mining area, providing sufficient time space for coal seam gas pre-drainage, to ensure the necessary time conditions for the pre-drainage to meet the standard; in view of the relatively low permeability of No. 8 coal seam and the rapid attenuation of drainage, the use of directional drilling and staged fracturing and anti-reflection technology is supplemented by high-efficiency sealing technology. In order to solve the problem of the abnormal gas emission problem in the large-scale gob formed after the ultra-long working face of the mine, the large-scale gob balanced pressure relief was proposed and implemented. The extraction technology effectively prevented the gas from the goaf from flowing into the mining space. Engineering practice shows that the coal seam gas pre-drainage rate is greater than 30% through the implementation of super-large area gas treatment technical measures in No. 8 coal seam of Baode Coal Mine, which effectively solves the problem of gas emission control during the mining of the working face, and the gas drainage in the whole process of mine production meet the standard; the monthly output of the mining face reaches 800 000 tons, and the monthly excavation of the tunneling face is more than 560 m, which realizes the long-term safe and efficient production of high gas mines. Practice has proved that the super-large area gas treatment technology has significant safety and economic benefits.