Abstract：As the source of the gas drainage, the reasonable hole-sealing-depth of gas drainage directly affects the effect of gas drainage. In order to determine the reasonable hole-sealing-depth of a Mengjin mine, the methods of gas desorption index and the quantity of drilling cutting are used to test the boundary of a distressed zone. On the base of the test, the axial delivery law of methane in different hole-sealing-depths down the seam with dedicated equipment is analyzed. At last, the reasonable hole-sealing-depth on the base of the delivery law of a methane is determined, and at the same time, the theory that the reasonable hole-sealing-depth shall be exceed the gas migration negative-pressure-affected zone is put forward. Through the application in a Mengjin mine, it shows that the reasonable hole-sealing-depth determined in this method is scientific and reliable. The application can improve the drainage gas concentration effectively, and then improve the gas drainage efficiency. This study can provide a reference for other mines.

Keyword：drainage hole down the seam;hole sealing depth;distressed zone;delivery law of methane;