Experimental And Numerical Study On Anti-Drag Of Axial Vibration Of Drill String

Drillstick vibration friction reduction technology is a cutting edge technology to improve the drilling efficiency and limit extension displacement of complex structure wells,which is of great significance to the efficient development of complex oil and gas resources and deep sea oil and gas resources and the safety of oil and gas resources in China.In this paper,the drill string vibration friction reduction technology research as the starting point,through numerical simulation and experimental combination of the way to carry out the drill string axial vibration on the load transfer law research,so as to drill string vibration reduction technology to provide theoretical application basis and guidance.Firstly,the load transfer model of the equal diameter drill string with axial exciter is established,and the numerical simulation is carried out based on this model.The amplitude,frequency and installation position of the excitation force are obtained.The influence of the transmission law,determine the best excitation frequency and installation location,optimize the drilling parameters.Secondly,the similarity principle is used to improve the experimental device.The size and material parameters of the drill string are determined.The ABS plastic rod is selected as the drill string material,and the PC transparent tube is selected as the wellbore material.The excitation device,Through the investigation and analysis,the principle of lever is established as the core principle of the development of the exciter,and the design and processing of the device is completed.The biggest advantage of the exciting device is that the frequency and amplitude control are independent of each other.The successful improvement of the experimental device laid the foundation for the next experimental study.Finally,by obtaining the field drilling parameters,the analysis is carried out,and thus the correctness of the axial vibration of the drill string should be further corrected.Finally,the effect of different excitation force amplitude,excitation frequency,axial load and the position of the exciter on the load transfer is studied by using the modified experimental device.The experimental results show that with the excitation the drag reduction efficiency increases first and then decreases with the increase of the excitation frequency.With the increase of the axial force,the drag reduction efficiency decreases;the exciter is installed close to the bottom position,get a larger bottom force.Compared with the simulation results,the indoor experiment has a high degree of coincidence,thus proving the success of the experimental device modification,but also for the practical application of vibration drag to provide a reliable guide.In this paper,the mechanism of the effect of axial vibration on the load transfer is studied systematically.The factors that influence the drag reduction of the drill string are analyzed by the combination of numerical simulation and experiment.The optimal excitation parameters are obtained,providing a theoretical basis to the field application of drag reduction technology.