F. Abbassian et Va. Dunayevsky, APPLICATION OF STABILITY APPROACH TO TORSIONAL AND LATERAL BIT DYNAMICS, SPE drilling & completion, 13(2), 1998, pp. 99-107
This paper addresses the dynamic stability of polycrystalline diamond
compact (PDC) bits under induced torsional and lateral vibrations. Dyn
amic stability is investigated by considering three simple mechanical
systems representing string-torsional vibration, bit-lateral dynamics,
and coupled torsional-lateral vibration of the bit-string assembly. F
or each system, the rotary-speed (rev/min)/ weight-on-bit (WOB) domain
within which the system is dynamically stable is determined. The infl
uence of various drillstring and bit parameters on the stability of bi
t motion is studied through their effect on the size of the stability
zone on (rev/min)/WOB plots. These illustrate the power of the stabili
ty approach in providing valuable qualitative information on the main
parameters influencing bit stability.