Abstract:The main coal seam of Wanfeng Mine has soft coal quality, poor permeability and uneven gas deposit, which makes gas extraction difficult and ineffective. In order to find out a complete set of technology to improve the concentration of gas extraction and further increase the gas extraction rate, we put forward the optimization technical measures such as “two plugging, one injection and one row” sealing hole, “DN150 confluence” connecting holes, and water discharge from the gas extraction branch pipe, etc., and carried out on-site experiments to get the optimization technical measures under the conditions of different extraction concentration and effect. Field tests were carried out to obtain the concentration and effect of extraction under different conditions of optimized technical measures. The results show that: the concentration of the new “two plugs, one injection and one discharge” sealing holes is generally above 70%, and the decay rate of the gas concentration is greatly reduced; after draining the gas extraction stub pipe, the concentration of the stub pipe is generally above and below 35%, and it is gradually improved with the increase of the continuous extraction holes. In order to provide a reference for safe and efficient coal mining at the face.
