1.Xi’an Research Institute，China Coal Technology & Engineering Group Corp., Xi’an ,China; 2.China Coal Research Institute, Beijing ,China

Based on the advantages of directional drilling technology, aiming at the shortcoming of connecting construction hole with rotary drilling and the problem of poor precision in directional drilling in early stage, the measuring instrument precision is analyzed then the optimal hole depth(100～400 m) and drilling site layout area are obtained(the angle between the drilling site and roadway should be more than 45°), Based on the analysis of the characteristics of long-distance and high-vertical distance boreholes, and on the basis of equipment performance and construction experience, an empirical value of 75%～80% of the theoretical maximum safety construction slope is proposed as the trajectory design construction slope, so as to leave room for adjustment. The influencing factors of drilling trajectory in each hole section are described in detail and the corresponding trajectory control method is put forward. It is pointed out that the aim of trajectory control of opening section is to keep straight, it is pointed out that the drilling trajectory of deviation rectification section is mainly affected by five factors: drilling parameters, formation dip, device angle, reverse torsion angle and the location of trajectory points. five factors are analyzed in detail and the trajectory control method is proposed. The requirement of trajectory space attitude, trajectory control and control method for target penetration are put forward to ensure that target penetration and vector target penetration are ensured. There are many influencing factors in trajectory control, which should be considered comprehensively and utilized in time according to specific needs, so as to realize the effect of guiding according to circumstances. The key technology and implementation method of accurate con-necting construction are systematically described. The field practice shows that the method can ensure accurate target of the drilling trajectory and accurate connecting construction and the drainage effect of the old tunnel is remarkable.

国家重点研发计划资助项目(2017YFC0804102)