Research On Sucker Rod Strength Evaluation For The Ground Progressive Cavity Pump

Rod parting is primary fault of the ground progressive cavity pump system. The static strength mechanical evaluation model is suitable for the vertical rod. The mechanical evaluation under alternative stress is more appropriate to the crooked rod. This thesis researches on the generating principle of alternative stress, which comes from the rotation of crooked rod, and establishes alternative stress calculation model based on the influence of well track imparting on the crook of tube and rod. According to the calculation model, the paper also analyzes effects of alternative stress on the rod fatigue failure besides builds model of force calculation and strength check when the crooked rod is rotating. More importantly, the thesis carries out analysis of the rod force including axial load and torque computation and check of the crooked rod alternative stress on the basis of model. Therefore, the thesis carries out the progressive cavity pump rod strength check under static load and alternative stress respectively. The paper also discusses some factors that have influences on the rod limit of fatigue and modifies the rod safety coefficient based on the relationship between effective factors and rod limit of fatigue. This thesis describes reasons of common troubles occurring on the rod system and illustrates corresponding techniques and methods. At last, this paper carries out force and strength analysis and evaluation of the rod system, making use of field data under the method established.