DEVELOPMENT AND APPLICATION OF THE THRUSTER

With the development of the petroleum industry,more and more re-entry wells,horizontal wells,slim hole and Extended Reach Well have appeared.For these wells,it is difficult for drill collars to provide WOB because of the high hole angle or big torque/drag.As a result,how to exert WOB is a problem concerned by drilling engineers.Hence two types of thruster which provide WOB by the drilling fluid have been developed.One can provide one kind of WOB named single-travel thruster and the other can provide two kinds of WOB named double-travel thruster.They have been used for hard formation,intermediate layer,re-entry and deep slim hole drilling in Tarim,Sichuan and Zhongyuan oil field etc..Using the thrusters,the WOB is smoothly applied on the bit,the bit-made axial vibration of the drill string above the thruster is reduced,the fatigue failure of the drill string and drill collar is decreased,the service life of the bit can be longer,and the ROP can be increased.