Lateral Vibration And Whirl Dynamics Analysis Of Horizontal Compressed Rotating Beam

With the development of drilling technology,directional drilling,horizontal wells,multilateral wells and other advanced drilling technology came into being,they has been widely used in various oil fields,horizontal well drilling technology has also been rapid development.Horizontal well technology is an important means to improve drilling efficiency and oil and gas production,but the variation of the horizontal well angle is large,the drill string friction is serious,with the increase of horizontal displacement,the drill string almost lying in the bottom hole affected by its own gravity,the nonlinear characteristics of the rotary drilling process are obvious,the lateral vibration is very easy occurred,the strong lateral vibration can also cause the formation of drill string whirl,it accelerate the wear of drill string,which will lead to the failure of drill string,bring huge economic loss to drilling engineering.Therefore,it is necessary to study the dynamic characteristics of horizontal well drill string.The research contents of this paper are as follows:According to Hamilton principle,a mathematical model is established to calculate the lateral vibration of drill string,which takes into account the drilling fluid in the drilling string and the drilling fluid in the annulus,the effects of internal and external drilling fluid velocity,drilling fluid density,drilling fluid viscosity coefficient,gravity,friction and drilling pressure on the lateral vibration of drill string are,by using the existing horizontal drill string dynamic simulation device in the laboratory,the fluid solid coupling characteristics of drill string lateral vibration under different drilling pressure and drilling fluid velocity are carried out,and compared with the simulation results.Based on the theory of rotor dynamics and fluid dynamics,the whirl equation of horizontal well drill string is established,the effects of WOB,shaft wall friction,internal and external drilling fluid velocity and fluid resistance on the drill string whirl were studied,based on the existing horizontal drill string dynamic simulation device in the laboratory,the experimental study on the characteristics of the horizontal drill string was carried out,the effects of WOB,rotational speed and fluid velocity on the whirl trajectory and whirl velocity were studied.