The pre-drainage cross layer directional drilling borehole from special designed gas drainage roadway, constructed by CCTEG Xi’an Research Institute was successfully completed in Guizhou Longfeng Coal Mine. Total borehole depth reached 312m, creating the deepest borehole record in the mining area where drilling is extremely difficult due to soft and outburst-prone coal seam geological condition.
The construction area has high gas content and complex geological conditions. In the first stage of drilling, it is necessary to pass through the pyrite metal hard nodules and the carbonaceous mudstone layer. In the second stage, the bottom of the coal seam is soft and easy to collapse, making it extremely difficult to form holes. After formulating a scientific construction plan, analyzing drilling problems in time, and adopting technical measures such as wide-blade milled auger MECCA, and down hole grouting technique. The borehole is accomplished smoothly.
The successful directional drilling construction provides technical support for the mine to control the gas in the coal roadway, solves the problem of the mine in the coal roadway and gas drainage, and lays the foundation for the gas control in large area. The foundation also paves the way for CCTEG Xi'an Research Institute to construct directional drilling in other areas and working faces of Longfeng Coal Mine.