Impact analysis on contact force between the rod and oil-tubing by rod string longitudinal vibration

The wear of rod string and tubing in pump well is a common phenomenon, and the main cause is the longitudinal vibration of sucker rod. Considering the structural characteristics and load characteristics, the contact state of rod and tube is studied and calculated using the finite element method, based on vibration theory and nonlinear contact theory. The results show that rod and tube contact friction mainly occurs in the down stroke, and the contact force is larger in the bottom, smaller in the top, and contact position is distributed mainly over the coupling, and has the contact between rod body and tubing within the scope of 150m. On this basis, various swabbing parameters which is about the degree of influence of the contact state is respectively studied, and the different swabbing parameters cause the different vibration load of rod string, and vibration load is larger, and dynamic instability is more serious, and contact force of rod tube is increased. On the basis of the above study, the proposal of value for preventing the rod and tube partial wear is given with some reference value.