Study on the technology of controlling upper corner gas by extra-large diameter borehole

In order to solve the problem that the process was unclear and the operation procedures were not standardized by using the technology of extra-large diameter borehole to control upper corner gas in practical application, with the method of combining theoretical research and field test, the technology of controlling upper corner gas by extra-large diameter borehole was studied. Operation and construction parameters of drilling rig which mainly based on drilling rig rotation rate, drilling speed and the efficiency of the transportation system were obtained. The construction technology of extra-large diameter drilling borehole technology was set up, including the six steps of the determination of bore spacing, the location of borehole, the construction of borehole, the construction of protective pipe, borehole sealing and the connection of pumping system. Field experiment results show that the technology can be applied to the underground coal mine operation, and the final height of the borehole is increased from 1.6 m to 3.0 m on average. The average time consumed by drilling from opening to whole hole laying down protection pipe is reduced from 7.6 shifts to 4.7 shifts and the construction efficiency is increased by 61%.