Fluid induced drilling dynamics: A mechanically scaled experimental investigation

Abstract

Drillstring vibration is an unavoidable detrimental dynamic response due to continuous acting external forces and dynamic loading applied during the drilling operations. Drillstring vibration is one of the primary reasons behind downhole equipment malfunctioning and premature fatigue failure. Laboratory scaled experiments gained much popularity to investigate the physics of induced vibrations by replicating the downhole vibrations phenomena, due to their economic design and versatility. The majority of laboratory scaled experiments oftentimes are only scaled geometrically and address isolated phenomena. Thus, most downscaled investigations provide limited insight and cannot relate to the overall dynamics of field conditions. The objective of this work is to design and fabricate a fully functioning mechanically scaled experiment and fulfill the experimental lacking of fluid hydrodynamic effects on drillstring vibrations. The developed experimental setup is equipped with a high-frequency vibration measurement system and the capability to capture the BHA trajectory. The setup was used to investigate the effect of WOB fluctuation on lateral motion and the effect of fluid flow on drillstring stability.