Drill Pipe Failure Analysis

Drill pipes are tools to transfer power and transport mud. Drill pipes often work in abominable conditions under alternating stress and the friction collision between drill pipe and borehole wall, which puts drill pipes in the weakest component in the whole drilling equipment and tools, the crack propagation results in perforation or part often emerge. The control that accidents and fractures of crack nucleation, propagation and washout in drill pipes are importance steps to keep drill pipes safe run. Hence, based on the preceding researches, using the finite element analysis and the experimental data, this paper carries out macroscopical and microcosmic analysis of drill pipes. The idiographic contents as follows:(l)The fracture surface analysis of typical drill pipes: This paper studies the appearances of fracture surface of drill pipes, on the basis of fracture appearances educes fracture mechanism of drill pipes, and makes out prophase work for mechanics and microcosmic analysis.(2)The fatigue and fracture analysis of drill pipes: By the method of finite element analysis, this paper simulates the bug of drill pipes and gains stress-concentration factor of drill pipes, works out fatigue life of drill pipes and by comparison of sensitivity which different parts of drill pipes to crack, elicits danger zone of drill pipes, and according to fracture mechanics and finite element analysis method obtains stress intensive factor.(3)The microcosmic analysis of drill pipes: Through comparison metallographic analysis of drill pipes, this paper finds out the ultimate reason which its' performance are difference, then uses SEM to analyze drill pipes and studies crack and acanthopore, measures local chemistry component and the influence that Shot-peened to performance of drill pipes in it's inside thickening transitional region, measures microcosmic rigidity of drill pipes.The primary innovation of this paper:(1) This paper brings forward the model of drill pipes' failure process and concept, bug inside surface- cleavage fracture-crack fatigue propagation-over loading fracture, puts forward analyzing methods and means for difficulties(each basic measuring parameter are mostly up to grade, but fracture and washout still happen )in the failure analysis of drill pipes. Brings forward reasons that drill pipes fracture and washout in the thickening transitional region is ending distortion temperature is too low when machining thickening, it can offers criteria for factory controlling quality of machining thickening.