FEM Analysis And Parameter Optimization Of Friction Reduction By Vibration In Drill Strings

In the slide drilling process in the Extended Reach Well, the friction between pipe end wellbore are very big and ROP is yell low because of non-rotation of the pipe,which restricts the drilling efficiency. Adding small vibration on several points of the pipe to vibrate the pipes in several parts can reduce the friction between the pipe and the bore. This paper reviews several technologies of friction reduction by oscillation, and introduces the mechanisms of that. The friction is depicted as Dahl model and the model of oscillation in several points of the pipe in wellbore is built. Then we used the lab data from National Oilwell Varco in 2007 to test our model. And we analysed and optimized the key parameters by the former model, sorted the significant parameters by orthogonal experiment. The locations of the tools of friction reduction by oscillation are optimized in the model of the friction reduction by oscillation in several points, which in one aspect increases the WOB and the ROP to the greatest extent and in the other aspect prevents the pipe from being damaged by severe oscillation and too much loss of pressure, which can cause negative influence to the drilling process. The numerical results show that WOB can increase a lot by friction reduction by oscillation technology, and the results become better if the locations of tools of friction reduction are optimized.