Analysis Of Vibration Characteristics And Experimental Research For Completion Tubing In Deep Well

Completion tubing is the critical channel for output and input fluid.Fluctuation of internal pressure and flow velocity can induce tubing’s vibration.Forced vibration can cause fatigue damage,wear-out failure and fracture of tubing.Knowing the vibration characteristic of completion tubing can help to ensure it work safely.Firstly,this paper analyses internal and external factors which can cause tubing vibration,deriving longitudinal and transverse vibration equation by energy principle and D’Alembert’s principle,solving the equation by separation variable method and boundary condition.Then,analysing influence of packer, modulus of elasticity,internal pressure,dimension to completion tubing’s natural frequency.After that,analysing tubing’s dynamic response by harmonic excitation,contrasting dynamic response of different working condition with same depth,different depth with same working condition.At last,taking stress as evaluation index to evaluate the safety of completion tubing when it get excessive vibration.The results show that,FSI natural frequency of tubing not only be related to dimension, modulus of elasticity,quality but also axial force,strided distance,velocity of flow.Applying constraint of packer,considering internal pressure and increasing wall thickness,external diameter, modulus of elasticity can increase tubing’s natural frequency.With certain tubing structure,responsed stress,responsed speed,responsed acceleration can reach maximal value in the middle of tubing.Besides, during well startup or shutdown,completion tubing’s vibration is excessive,even can cause plastic deformation of completion tubing.