Identification and Mitigation of Friction- and Cutting-Action-Induced Stick/Slip Vibrations with PDC Bits

In this paper, we provide some new insights into stick/slip vibration in drilling with polycrystalline diamond compact (PDC) bits. Fifty-six field runs under various drilling conditions were collected with the help of on-bit vibration sensors. Stick/slip vibration occurrence during drilling was analyzed. Two types of stick/slip vibrations were identified: cutting-action-induced stick/slip and friction-induced stick/slip. Methods were developed to determine whether a stick/slip occurrence is induced by cutting action or by friction. Statistical analysis found that bit drilling efficiency (DE) is well correlated with the occurrence of cutting-action-induced bit stick/slip vibration. If a PDC bit is designed so that its DE is greater than a critical value, then the cutting-action-induced bit stick/slip vibration is not expected in drilling. Increasing the aggressiveness of the cutting structure of a PDC bit within a limited critical depth of cut is found to be helpful to mitigate bit stick/slip vibration.