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COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Stochastic torsional vibration analysis of a vertical drill-string in the transition between two rock layers
Submission Author:
Daniel de Moraes Lobo , RJ
Co-Authors:
Thiago Ritto, DANIEL CASTELLO, Daniel de Moraes Lobo
Presenter: Daniel de Moraes Lobo
doi://10.26678/ABCM.COBEM2017.COB17-0341
Abstract
Undesired vibrations in drill-strings, like stick-slip oscillations, reduces drilling performance and increases the costs. The main uncertainties in drilling operation are because of bit-rock interaction and becomes more important when variations in the rock being drilled are observed. This work is focused on the modelling of the uncertainties in bit-rock interaction when there is a transition between two rock layers and the consequences in torsional dynamics. The drill-string is modelled with one degree-of-freedom where the top speed is prescribed, a viscous friction represents the drilling mud and a non-linear model describes bit-rock interaction. Rock strength data available in literature served as inspiration to build models to describe rock layers transitions; moreover, uncertainties are included in the parameters. The stochastic dynamic response of the system is assessed and the conclusions are presented.
Keywords
drill-string dynamics, rock transition, stochastic, bit-rock interaction
