Doctor of Philosophy (PhD)
Rotary drilling system vibration has long been associated with damaging the bit, the bottom hole assembly (BHA) and drill string. Vibration has been traditionally measured in the bottom hole assembly, and been closely associated with the resonant behaviors.
This research study proposes an improved physical laboratory model to explore the dynamic behaviors associated with vibration. This model includes contact with the borehole wall allowing a range of stabilization geometries while removing bit-formation interaction effects. The results of exercising the model help develop new insights into both vibration measurement diagnostics and mitigation strategy execution.
Presented here is a review of other physical bottom hole assembly and drilling concepts, and a new novel model. Experimental investigation using the new model for a range of geometries is presented with recorded conditions, annotated video stills and analysis using regression and response surface methods. The analysis when compared to existing industry mitigation methods allows unique insight to the possible effectiveness of such methods. A numerical simulation of the system was also performed and its results compared to the laboratory tests. Results show that a shaft system alone can generate stick-slip and whirl behaviors. Such behaviors occur in distinct regions. Another conclusion of this work is that a popular method for inferring stick-slip from acceleration measures is not reliable for the system used in this study.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Duff, Richard, "An experimental and computational investigation of rotating flexible shaft system dynamics in rotary drilling assemblies for down hole drilling vibration mitigation" (2013). LSU Doctoral Dissertations. 1734.
Tyagi , Mayank