1. Introduction
From geophysical interpretation result, there is a fault (fault FD13 strike N89°E,Dip s 1°W,dip angle about 60 °,control length 1156 m, fault No. 2 Coal Seam, No. 3 coal seam, maximum drop 20m) in the north side of 22110 working face in Yaping Coal Mine. Directional drilling is used for fault detect and verification.
2. Solution
By using directional drilling, sidetrack drilling technology and three-point-one-line identification method, the top and floor of coal seam and the position of fault are identified, and the spatial shape information of fault is obtained.
3. Construction situation
The drilling field is designed at 1300m in tailentry of 22110 working face.1# and 2# boreholes are arranged on the upper wall of the fault. Spacing between the boreholes is 1 m. Borehole start at 667 meter elevation, with 1.47m distance from the coal seam floor. The position of the borehole start point is about 300m from the fault interpreted by geophysical prospecting. Using the advance construction method, while constructing the main hole, the branch holes 2-1#, 2-2#, 2-3#,1-1#, 1-2# and 1#main holes and 2# main holes are successively constructed with a total drilling footage of 1060m.
4. Achieved accomplishment
Underground directional drilling is used to realize the precise detection task, and the construction of 2 main bore holes and 5 sidetracks has been successfully completed. Basing on the result, mining area of the working face was redesign and was enlarged by 56.4m. Thus, 53690t coal resource reserve was increased. It is shown that the difference between the exploration fault position and the actual exposure position is only 0.8m, which is much less than the design error and achieves the expected effect.
Trajectory diagram of 2# directional drilling borehole and sidetracks (profile)
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