Stick-slip, a mode of drilling dysfunction characterized by a cycle of the bit coming to a stop and accelerating to speeds greater than the mean bottom-hole assembly (BHA) speed, has become an important risk element in oil and gas drilling operations. Awareness of stick-slip, which is largely a vibration-related phenomenon, has increased in part due to the rise of polycrystalline diamond compact (PDC) cutters that drill through rock with sheer rotary force. When stick-slip occurs at the end of a drillstring, the resultant release of accumulated energy causes extra twist in the string, which can cause severe bit damage. This can happen during both torsional and lateral vibration during the stick and slip phases.
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