我国煤矿井下复杂地质条件下钻探技术与装备进展

钻杆长期服役会不可避免地发生断裂并导致掉钻，严重影响了钻孔施工效率和成孔率，还会给煤矿带来重大经济损失。针对施钻过程中钻杆随机断裂导致的掉钻问题，指出了丝锥打捞技术存在的不足，通过分析钻杆断裂特点，得出解决掉钻难题的关键是研究公接头断裂后的轴向连接技术。提出具有断裂自锁功能的主动防掉技术，阐述了其技术原理，介绍了防掉钻杆设计原则，设计并研制了ø73 mm防掉钻杆。室内实验结果表明，钻杆抗扭能力20 120 N·m，抗拉能力1 444 kN，公接头断裂后的二次抗拉能力384 kN。并在山西焦煤西山煤电(集团)有限公司进行工业性试验，200根钻杆累计进尺43 757 m，发生的5次断裂事故均位于公接头螺纹根部区域，其中4次直接将断点以深的钻杆全部提出，另1次因孔内严重埋钻未能提出孔内钻杆。现场试验结果表明，该钻杆结构合理，具有良好使用寿命和可靠的主动防掉能力。研究可为钻杆设计提供新方向，为煤矿井下钻孔安全高效低成本成孔提供钻具支撑。

Progress of drilling technologies and equipments for complicated geological conditions in underground coal mines in China

Drill pipe will inevitably break and drop during its long-term service, which not only seriously affects the drilling efficiency and the rate of hole formation, but also brings great economic losses to coal mines. In terms of drill pipe drop caused by the random fracture during drilling, the shortcomings of fishing tap were pointed out. By analyzing the fracture characteristics of drill pipe, it is concluded that the key to solve the problem of drill pipe drop is to develop the axial connection technology after the fracture of pin joint. Herein, an active anti-drop technology with fracture self-locking function was proposed, with its technical principles and the design principles of anti-drop drill pipe introduced. On this basis, a ø73 mm anti-drop drill pipe was designed and developed. Laboratory tests showed that the anti-drop drill pipe had a torsional resistance of 20 120 N·m, a tensile strength of 1 444 kN, and a secondary tensile strength of 384 kN after the pin joint fracture. Besides, the anti-drop drill pipe was subjected to the industrial test by Shanxi Coking Coal XiShan Coal Electricity Group Co. Ltd. During the test, the accumulated drilling footage reached 43 757 m by 200 drill pipes, and 5 fracture accidents occurred at the root area of pin joint thread. Specifically, the drill pipe below the fracture point was fully taken out in 4 accidents, but the drill pipe was failed to be taken out in one accident due to its deep burial in the borehole. The field test results show that the anti-drop drill pipe has reasonable structure, long service life and reliable active anti-drop capability. Generally, the research could provide a new direction for drill pipe design, as well as drilling tool support for the safe, efficient and low-cost drilling in underground coal mine.