Theoretical Modeling and Application of Surface Drill String Torsion Pendulum Steering Drilling
In slide steering drilling,the torsion pendulum of the drill string can change the static friction be-tween the wellbore and the drill string during the drilling process to a sliding friction,thus effectively reducing the drilling friction and alleviating the common"backing pressure"situation in slide drilling.Based on slide drilling technology,the torsion pendulum motion control equation of drill string was established by zones.The theoretical model was used to identify the influences of torsion pendulum angle(100°-600°)and velocity(20-80 r/min)on the torsion pendulum depth,weight on bit(WOB)and tool face changes.Finally,the drill string torsion pendulum test device was used for tests.The research results show that as the torsion pendulum angle and velocity increase,the torsion pendulum depth increases,the WOB tends to stabilize,and the drag reduction effect of torsion pendu-lum is better.However,excessive increase in torsion pendulum angle and velocity would cause tool face to fluctuate and affect drilling efficiency.The field application results show that the coincidence rate of tool face smoothness is as high as 96%,the"backing pressure"prevention effect is obvious,meeting the requirements of field operations.The research results provide technical reference for the drill string torsion pendulum steering drilling technology.
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