| dc.description.abstract | In this study, an extensive assortment of the principal studies related to drill-string vibrations is presented, focusing on analytical studies, finite element models and experimental setups. A discussion on the current limitations of the current experimental research is discussed and is used to design a new experimental setup that will cover most of those limitations. Two finite different studies are presented. The first study compares six different cases to a simplified bottom-hole-assembly and concludes that when all three modes of vibration are induced in the system, the vibration response will be lower than when a single mode of vibration is applied. The second study extended the scope of the previous study and modelled the behavior of the downscaled geometry proposed for the experimental setup, comparing four different materials when one mode of vibration is induced versus all modes of vibration. The results are compared graphically and numerically using the damping ratio and response frequency. Additionally, a modal analysis comparing the first 140 modes of natural frequencies is presented for the four studied materials. It was concluded that, similarly to the previous study, the vibration response is lower when all modes of vibration are applied than when only one mode is induced. It was concluded as well from this study that when one mode of vibration is applied, the behavior of the vibration response is predictable according to known analytical models, but when all modes are present in the system, the behavior will vary considerably. Finally, a in detail description of a designed and build experimental setup is presented and the future steps are described in order to ultimately mitigate downhole vibrations in a safe, cost effective and environmentally responsible manner. | en_US |
