Research On The Working Mechanism Of High-frequency Micro-amplitude Rotary Vibration Drilling Tools

During the drill string mechanics,the drill string system vibration is one of the major problems of the researchers concerned.Drill string vibration can reduce drilling efficiency and cause the failure of drilling equipment.The vibration control has become one of the key factors in drilling engineering.In view of the stick-slip phenomenon in the drilling technology,a new type of downhole tools has been designed and put forward.Based on the collision theory,the following researches for high frequency and slight vibration torsional tool have been done by using mechanical,mechanics,mathematics and related software and other research methods.Compared with the existing downhole tools,the tools can provide a certain amount of axial impact at the same time as it rotates.the bit supports circumferential impact load in the process of rock fragmentation,which would change the torque of drill bit.It also has a torsional rock-breaking at the same time in the longitudinal impact of rock damage,and the method can reaches the purpose of improving the efficiency of drilling.According to the different relationship of motion,the kinematics equations of the impact generator eccentric strap and the impact generator transmission shaft are established.And the relationships of their angular velocity and angular displacement with the change of time are obtained.In the meantime,through the analysis of the collision of the process and the contact time,the relationship of the average torque and collision frequency of the vibration drilling tools with inlet flow,the inlet pressure are received.Next,the research on the dynamics of high frequency and slight vibration drilling tool are considered under two kinds of circumstances.When considering vibration drilling tools separately,assuming that the transmission shaft and eccentric annulus collision of vibration drilling tools is the impulse response of the ideal situation,and the establishment of a single degree of freedom without damping impulse vibration equation is accomplished.The vibration characteristics of drilling tool vibration angular displacement and angular velocity in the process of collision are researched.When considering the whole drill string system,establishing the corresponding multiple degree of freedom vibration model and torsional vibration equation,the components of the vibration angular displacement and angular velocity changes over time are concluded by examining drill string system whether considering high frequency and slight vibration drilling tool or not.In order to verify the accuracy of theoretical calculation,three-dimensional model of the high frequency and slight vibration drilling tool is imported in Automatic Dynamic Analysis of Mechanical System(ADAMS).the movement process of vibration drilling tools and multi-body dynamics simulation of collision parts are simulated.By setting kinematical boundary conditions of the impact generator,the relationships of impact torque of drive shaft generator and eccentric annulus,collision cycle,eccentric annulus velocity and the drive shaft angular velocity over time are obtained.And the results were compared with the theory of above.From the above,based on the design and expounding of the high frequency and slight vibration drilling tool,the motion models of torsional vibration drilling tool collision system are established in this paper.The angular velocity,angular displacement of key components,the collision torque and collision frequency are researched.Considering high frequency and slight vibration drilling tools separately and the entire drill string system,the torsional vibration model of different degrees of freedom are established and torsional vibration drilling tool their vibration and its effect on the vibration of the whole drill string system are researched.At the same time,using the ADAMS simulation software,the vibration drilling tool collision process of multi-body dynamics simulation analysis is conducted.The accuracy of the theoretical model and its result is verified,which provides theoretical basis for subsequent laboratory test and underground experiment.