A MODEL FOR THE TRANSVERSE VIBRATION SIMULATION OF SUCKER ROD STRINGS WITH AXIAL RECIPROCATING MOTION IN CURVED WELLBORES

The research on the transverse vibration of sucker rod strings (SRSs) is the basis of analyzing the eccentric wear phenomenon between the SRS and the tube string. The transverse vibration of the SRS in the curved wellbore of the directional well is simplified as a transverse vibration problem of a longitudinal-transverse curved beam with initial bending and tube constraints. In addition to the transverse vibration excitation of the SRS caused by alternating axial loads, the curved wellbore is taken as the main transverse vibration excitation for the axially moving SRS for the first time. Based on the elastic body vibration theory, the transverse vibration simulation model of the SRS with initial bending in the curved wellbore is established. In this model, the transverse vibration excitation for the axially moving SRS caused by the curved wellbore and the alternating axial load are considered. The elastic collision theory is applied to describe the tube constraint to the SRS transverse vibration. The finite difference method and Newmark method are used to simulate the transverse vibration of the SRS in the directional well. The simulation results show that the simulation results are consistent with the actual eccentric wear situation in the oil field, and therefore the curved wellbore excitation caused by the axial movement cannot be ignored in analyzing the SRS transverse vibration. And for the example well, the eccentric wear dangerous points between the SRS and the tube string are located in the wellbore deviation section and the SRS compression section. The transverse vibration simulation model of the SRS in the directional well can be used to guide the optimal configuration of sucker rod centralizers.