Transverse Vibration Simulation And Simulator Design Of Sucker Rod String In Curved Wellbore

In recent years,the number of curved oil wells is increasing gradually in China,and the sucker rod string is more prone to bias wear in curved hole,and the sucker rod string will break and fall off in serious cases,which directly affect the efficiency of the oil well.In order to prevent and deal with eccentric wear of sucker rod string better,the transverse vibration mechanical characteristics of sucker rod string in curved wellbore are studied in this paper,and a simulator of transverse vibration and dynamic buckling of sucker rod string is designed.The main research contents are as follows:Considering the influence of coulomb friction force,and considering the longitudinal vibration excitation of sucker rod string by suspension point movement of pumping unit and liquid load of plunger,the nonlinear longitudinal vibration simulation model of rod string in curved wellbore is established,the change law of axial concentrated load and axial distributed load distribution of sucker rod string are simulated.The transverse vibration of the rod string between adjacent centralizers in the curved hole is simplified into the transverse vibration model of the longitudinal-transverse curved beam whose transverse vibration displacement is constrained by the wellbore.Considering the axial alternating load on the sucker rod string as excitation,and considering the initial bending of the sucker rod string and the constraints of the wellbore on the transverse displacement of the sucker rod string,the longitudinal-transverse curved beam nonlinear transverse vibration simulation model which between adjacent centralizers is established.The nonlinear vibration characteristics of rod string under different parameters excitation are analyzed.Considering the excitation of transverse vibration of sucker rod string in axial reciprocating motion by curved borehole and the excitation of transverse vibration of sucker rod string by alternating axial load in curved wellbore,the elastic collision theory is applied to describe the constraint of lateral vibration displacement of sucker rod string in wellbore,and the transverse vibration elastomer simulation model of integral rod string in curved wellbore is established.The influence of borehole trajectory,production parameters and centralizer configuration scheme on transverse vibration and collision force are analyzed.A hydraulic loading simulator for transverse vibration and dynamic buckling of sucker rod string is designed,which can realize the program control of alternating axial force at the end of sucker rod string.The hydraulic alternating axial pressure control system simulation model is established based on Simulink,and the simulation results show that the hydraulic loading system can output the expected alternating axial force.