Deep Well Drill Stabilizer Failure Analysis And Design

The statistics of drill tool failures from the oil field shows that failures of the stabilizer are large part of failures of drill tool failures. According to the domestic and overseas datum of the stabilizer, after analyzing failure of the stabilizer, Primary failure mechanism has been found. Research and design will be carried out in three aspects that are the wall contact, the thread joint and the fishing neck of the stabilizer. The measures that improve the stabilizer will be put forward, for extending used life of the stabilizer.Through failure analysis of stabilizer, there are three main types in failure form of the stabilizer: First, the threads are adhered or pierced. Second, the thread joint fractured in fatigue. At last, the face of wall contact sunk below the tungsten carbide slugs for abrasion and erosion, whereas because the tungsten carbide slug extend out of the face of body, that will be prone to snap and come off. Then the failure that is reduction of diameter of wall contact occurs. As concerning the key of wall contact life is wear resistance character of body materials. It is recommended that cast tungsten carbide is applied by oxygenacetylene flame on the wear face of body among the tungsten carbide slugs, for improving wear resistance character of body materials. Through the contrast experiences of selected wear resistance materials, the cast tungsten carbide is used as wear resistance materials to improve wear resistance character of body. By means of Transmission Electron Microscope analysis to the surface of specimen, the result of failure analysis has got corroboration. Other frequent failure region is in the thread joint. Thus the force of stabilizer is calculated under the action of pretightening force and axial force. According to the result of fatigue count, it was one high stress raiser for thread root. That the thread endures high alternate stress is the first cause of failure of thread joint. As concerning the design of thread joint, a great deal of improvement is brought forward.It is recommended that the stress relief groove is in the body of stabilizer. This will decrease not only the stress maximum of body but also that of thread joint. As concerning slug depth, width and distance to thread joint, FEA model is erected and the incidence to the stress maximum is analyzed.