Research on Transient Mechanics Behavior of Pumping Rod in Pumping System

More than 75% pumping rod well accounted is artificial lifting production well. With the development of the oilfield, eccentric wearing of rod is becoming the main problem. Numerous factors influencing eccentric wearing of rod heighten the difficulties in the prediction and comprehensive analysis. In the past, it is emphasized on the avoiding and curing measures application, and short of system analysis in respect of flectional reason, flectional conformation and influencing factors. In order to reduce eccentric wearing of rod and show the flectional conformation, the transient mechanics behavior research of pumping rod should be researched deeply. The pumping rod is the extra slender flexible rod. Its working state back and forth moving in the process of the pumping oil, the mechanics behavior is very complex including geometric nonlinear, contact nonlinear and dynamics state. The kinematics equations of pumping rod are deduced adopting the updating lagrange based on the finite deformed theory and the contact constraint equation is confirmed by contact theory. The discrete form of equations can be acquired by using the finite element method. The contact dynamics equation can be obtained by coordinates transformation and elements integration. It is shown the flectional modality and the contact state with the load incremental method and Newmark method utilized in the equation solved. Basing on the research, the swab parameters can be optimized and the centralizer can be rational installed to guarantee normal work and extend the inspecting pump cycle.