Application of mouth section hole forming technique for directional drilling in Yangquan Mining Area

In the construction of long borehole in coal mine, the construction of the start of directional drilling is not paid enough attention. Especially for the installation of the ultra-deep casing(≥100 m), the casing is often not in place due to the hole trajectory deviation or casing tubes thread tripping, which results in the abandonment of borehole, extension of construction period or waste of materials. By analyzing the causes of common accidents in the initial section of directional drilling, a set of pilot hole and straight hole forming technology for drilling tools after optimization is put forward. The technical problem of drilling technology in the initial section is solved. According to the engineering practice and application in Yangquan Mining Area, the optimized process has a good effect and it is economical and practical.