Author:
Ji Nan,Wang Peng,Feng Chun,Zhu Lijuan
Abstract
Abstract
In recent years, the frequency of drill pipe failure accidents has increased during ultra-deep well drilling process. The fracture failure of pin joint of a 5-7/8” drill pipe happened in an ultra-deep gas well after thirty-five hours’ service. Failure causes were investigated by physical and chemical properties test of the material, macro and micro feature analysis of the fracture surface. The results showed that the physical and chemical properties of the drill pipe were all satified the corresponding standard requirements, the fracture of mode of the dill pipe is fatigue fracture, which was attributed to the harsh load condition during the reaming operation. Furthermore, the increased inner diameter of the pin joint also gives an acceleration of the fatigue fracture process.