The following problems should be paid attention to when drilling guide holes with horizontal directional drilling rig

① In the process of drilling weathered granite layer, if the drill bit encounters dikes or pebbles with larger particle size in the process of drilling pebble layer, the drilling trajectory may deviate from the design trajectory significantly, and the deviation of the drill bit is difficult to predict at this time. When the operator realizes that the drill bit encounters small changes such as hard objects or difficult drilling conditions, he should stop drilling immediately and check the position of the drill bit. At this time, the WOB should be reduced and feed in slowly, so that the drill bit can slowly pass through the area. When drilling, the position of the drill bit should be detected more frequently.

② When the bit encounters a hard formation, it is usually necessary to increase the WOB. However, the increased WOB will cause the drill pipe in the hole to bend. If the formation at the bending part of the drill pipe is soft, the bent drill pipe will expand the drilling hole. The directional probe can only determine the position of the drill bit, and it is difficult to determine the drilling trajectory formed by the bending of the drill pipe. In this case, it is necessary to appropriately reduce the WOB, try to use the impact drilling method to pass through the hard formation, and at the same time, increasing the pump capacity or spraying may help to soften the obstacles.