Research on BHA Load Transfer Considering Drill String Transverse Vibration

Abstract

With increasing difficulty of reservoir development and harsh geological conditions, higher drilling technology meets lots of challenges, especially in the large displacement wells and ultra-deep wells. For Limit Extension Well, not only good drilling equipment is needed, but also drilling technology and basic theory are acquired. Bottom hole assembly (BHA) load transfer rule has important influence on Limit Extension Well. Therefore, on the basis of previous research, BHA load transfer rule is studied which considers the influence of drill string transverse vibration, and sensitivity analysis based on affecting factors of BHA load transfer rule. Research results show that transverse vibration of drill string has greater influence on the axial force and torque transfer. With the increase of friction coefficient and azimuthal variation, friction and torque of BHA increases linearly; with the increase of weight on bit (WOB), friction and the rate of torque of BHA also goes up. The application of model considers drill string transverse vibration, which will not underestimate values of loads like previous dynamic models. It will support optimal BHA design and prevent early drill string failures. Therefore, the influence of transverse vibration cannot be ignored on load transfer in large displacement wells. Key words: Drill string; Transverse vibration; Bottom hole assembly; Load transfer; Limit extension well