Stick-slip vibration presents one of the major causes of drilling problems,such as premature tool failures,low drilling efficiency and poor wellbore quality.The objective of this work is to investigate the influences ...Stick-slip vibration presents one of the major causes of drilling problems,such as premature tool failures,low drilling efficiency and poor wellbore quality.The objective of this work is to investigate the influences of rotary table speed(RTS)on stick-slip phenomenon of the drilling system.In this study,the drilling system is treated as a lumped torsional pendulum model of which the bit/rock interaction is regarded as Coulomb friction.By analyzing cases with different RTS,two types of vibrations on the bit are found:stick-slip vibration and uniform motion.With an increase in the RTS,the stick-slip vibration on the drill bit disappears once the RTS arrives at its critical value.For the cases that stick-slip vibrations occur,the phase trajectories converge toward a limit cycle.For the cases that stick-slip vibration does not appear,the drill bit tends to stabilize at a uniform motion and the phase trajectories correspond to contracting spirals observed in the phase plane.展开更多
In this paper,the stick-slip vibration in oilwell drillstring is studied.The drilling system is modelled as a lumped-parameter torsional pendulum and the interaction between the drill bit and the rock is treated as Co...In this paper,the stick-slip vibration in oilwell drillstring is studied.The drilling system is modelled as a lumped-parameter torsional pendulum and the interaction between the drill bit and the rock is treated as Coulomb friction.Equation of motion of the drill bit is established and the dynamic responses of the drill bit are obtained.A drilling system with the drillstring length 3000 m is analysed,in which the system parameters are selected by reference to the actual drilling situation.After the slip vibrations in the initial stage,final state of the drill bit is a stable stick-slip vibration of which the limit cycle is a closed loop.In order to find the stability of the limit cycle corresponds to the periodically stick-slip vibration,different initial conditions for the drill bit are studied.Results show that the drill bit will lead to a periodic motion and the phase trajectories ultimately converge to the same limit cycle corresponds to stable stick-slip vibration.展开更多
基金This research is supported by the National Natural Science Foundation of China(Grant No.51222406)New Century Excellent Talents in University of China(NCET-12-1061)+2 种基金Scientific Research Innovation Team Project of Sichuan Colleges and Universities(12TD007)Youth Scientific Research Innovation Team Project of Sichuan Province(2014TD0025)the key projects of academic and technical leaders cultivate fund in Sichuan Province,China(2011-441-zxh).
文摘Stick-slip vibration presents one of the major causes of drilling problems,such as premature tool failures,low drilling efficiency and poor wellbore quality.The objective of this work is to investigate the influences of rotary table speed(RTS)on stick-slip phenomenon of the drilling system.In this study,the drilling system is treated as a lumped torsional pendulum model of which the bit/rock interaction is regarded as Coulomb friction.By analyzing cases with different RTS,two types of vibrations on the bit are found:stick-slip vibration and uniform motion.With an increase in the RTS,the stick-slip vibration on the drill bit disappears once the RTS arrives at its critical value.For the cases that stick-slip vibrations occur,the phase trajectories converge toward a limit cycle.For the cases that stick-slip vibration does not appear,the drill bit tends to stabilize at a uniform motion and the phase trajectories correspond to contracting spirals observed in the phase plane.
基金This research is supported by the Natural Science Fund for Outstanding Youth Science Fund(Grant No.51222406)New Century Excellent Talents in University of China(NCET-12-1061)+3 种基金Scientific Research Innovation Team Project of Sichuan Colleges and Universities(12TD007)Youth Scientific Research Onnovation Team Project of Sichuan Province(2014TD0025)the key projects of academic and technical leaders cultivate fund in Sichuan Province,China(2011-441-zxh)Sichuan Science and Technology Innovation Talent Project(20132057).
文摘In this paper,the stick-slip vibration in oilwell drillstring is studied.The drilling system is modelled as a lumped-parameter torsional pendulum and the interaction between the drill bit and the rock is treated as Coulomb friction.Equation of motion of the drill bit is established and the dynamic responses of the drill bit are obtained.A drilling system with the drillstring length 3000 m is analysed,in which the system parameters are selected by reference to the actual drilling situation.After the slip vibrations in the initial stage,final state of the drill bit is a stable stick-slip vibration of which the limit cycle is a closed loop.In order to find the stability of the limit cycle corresponds to the periodically stick-slip vibration,different initial conditions for the drill bit are studied.Results show that the drill bit will lead to a periodic motion and the phase trajectories ultimately converge to the same limit cycle corresponds to stable stick-slip vibration.
