Transient dynamic model of the rod string of single-screw pump oil production system rod and its application

The mathematical model of pumping rod movement is the theoretical basis of the optimization design, the dynamic performance prediction and working-condition diagnosis of oil-well production system. Surface-driven single-screw pump oil production system is analyzed using finite element method, and the transient dynamic model of the pumping rod string of it is established. The establishment of the model overcomes the shortcomings of the static model of it that can't dynamically reflect the movement and the force-bearing condition of the pumping rod string. The torque curve of the pumping rod string with time at any position and the lateral displacement of the pumping rod string at any moment are obtained by solving the dynamic model with Newmark direct integration method. Because the contact impact between pumping rod string and tubing is considered in this model using classical impact theory, the force-bearing condition and the movement condition of the pumping rod string can be more truly reflected by this model. At the same time, the model establishes theoretical basis for the design of the centralizers of screw pump well. The application of the software compiled with this model in Erlian oilfield proves the veracity and the practicability of the model.