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通过断口宏观分析、金相组织及能谱分析和力学性能测试,并结合钻杆失效前的钻井情况,对一例ф101.6mm钻杆外螺纹接头断裂失效原因进行分析。结果表明:在钻杆接头材质符合API Spec 5DP和SY/T 5561-2014标准要求的前提下,由于钻杆公接头斜坡台肩周围发生岩屑大量堆积导致钻杆断裂失效。外螺纹接头与堆积岩屑发生剧烈摩擦,导致摩擦部位温度大幅度上升,材料承载性能降低,在扭转、拉伸复合载荷的作用下发生接头断裂失效。
Through a macroscopic fracture analysis, microstructure and energy spectrum analysis and mechanical properties testing, combined with drilling before the failure of the drill pipe, the failure reason of a ф101.6mm drill pipe threaded joint was analyzed. The results show that when the material of drill joint meets the requirements of API Spec 5DP and SY / T 5561-2014, the drill rod fracture failure will occur due to the large accumulation of cuttings around the shoulder of the drill joint. Fierce friction between the male connector and the accumulated cuttings leads to a sharp increase in the temperature of the friction part and a decrease in the bearing capacity of the material. The joint failure occurs under the action of torsional and tensile composite loads.