Historically, prediction of stick/slip vibrations in advance of drilling has been fraught with challenges. Although the factors influencing stick/slip, and the directional changes required to mitigate it, are known, a need exists for a simple method to determine quantitatively the degree of dysfunction and the effects of redesign parameters. This paper will show how stick/slip vibration distributions can be used to guide drillstring and parameter redesign to mitigate stick/slip in the next well.
Background
Torsional vibrations, also known as stick/slip, occur as the rotational speed of the bit and drillstring vary because of stiffness, inertia, and torsional friction interactions. In some wells, these torsional/rotational fluctuations are not severe and may not reach full stick/slip, which occurs when the bit comes to a full stop in the torsional vibration cycle.
The drilling data obtained in the drilling of a well are displayed typically as time or depth tracks, with different parameters shown on the same or adjacent tracks over the corresponding time or depth interval.
