The Genesis of Bit-Induced Torsional Drillstring Vibrations
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Abstract
The work presented here shows that inherent drilling characteristics of PDC
bits alone can he sufficient to excite severe torsional drill string vibrations.
Lab and field torsional measurements are compared with model results to show
that the observed vibrations can be explained by a reduction in PDC bit torque
with rotary speed. These torsional vibrations are important because they can
cause drill pipe fatigue, and may be severe enough to damage the bit. The
model is also used to determine possible solutions to the problem.