Gas leakage detection of gas extraction drilling and influence of coal seam pressure relief
The deformation and failure of the gas extraction drilling and the development of fracture network will lead to the gas escape in the coal seam during the extraction process,thus reducing the gas extraction effect.In order to explore the de-formation,failure and leakage characteristics of the gas extraction drilling,taking the gas extraction project of the coal seam on the 820 working face of Huangling No.1 Mine as an example,the stress zoning characteristics and fracture development state of the drilling as the change of drilling depth were analyzed.The gas concentration variation rule of the drilling along the return air channel was analyzed by using the drilling leak detection device.The evolution law of gas concentration and pure quantity in inlet channel and return channel is compared,and the gas leakage characteristics of drilling are explored.The results show that the fracture development degree of extraction drilling changes gradually with different stress zones of drilling depth.Due to the pressure relief of coal seam,the gas leakage in the drilling is high,and there are three gas concen-tration variation trends,i.e.,gentle type,16～19 m gas leakage type,and 19～23 m gas leakage type.The gas concentration and pure quantity of the inlet channel show a decay law in the form of negative exponential.Because the coal seam has not relieved pressure,the fracture network in the coal seam is relatively developed,and the drilling is well sealed.In contrast,the gas concentration of the return air channel shows a linear decay law,and the gas leakage degree of the gas extraction drilling is higher due to the coal seam pressure relief.
gas extractiondrilling deformationgas leakage detectionextraction concentrationcoal seam pre-ssure relief
万方数据
维普
