对某井在钻井期间发生的钻杆断裂事故进行了详细调查研究。对裂纹的钻杆样品断口进行了宏观分析和微观分析,对断裂钻杆材料的化学成分、机械性能和金相组织进行了全面试验分析。最终结合钻杆使用情况和试验分析结果对钻杆接头断裂和裂纹的原因进行了全面分析讨论,认为钻杆接头断裂和裂纹原因是该部位结构尺寸不合理,应力集中严重所致。 A detailed investigation was made on the drill-pipe fracture accident occurred during the drilling of a well. The macroscopic and microscopic analyzes of the fracture of the cracked drill pipe sample were carried out. The chemical composition, mechanical properties and microstructure of the fracture pipe material were comprehensively tested. In the end, the causes of fracture and crack of drill joint are analyzed and discussed based on the use of drill pipe and the test results. It is concluded that the fracture and crack of drill joint are caused by the unreasonable structure size and serious stress concentration.