On “Lump mass torsional vibration model” and helical deformation of drill string

• Main Author: Zifeng Li
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2021-02-01
• Series: Petroleum
• Subjects: Drill string; Vibration; Axial; Torsion; Boundary
• Online Access: http://www.sciencedirect.com/science/article/pii/S2405656119301233

This paper analyses the physical models in “Kapitaniak M, Hamaneh VV, Chávez JP, Nandakumar K, Wiercigroch M. Unveiling complexity of drill–string vibrations: experiments and modelling. International Journal of Mechanical Sciences 2015; 101–102: 324–327”. The results are that the physical models described in the original paper are clearly incorrect. For the physical model used to explain the axial vibration on a drill string, using a lumped mass-axial spring with damping to model a long slender drill string is not advisable. For the physical model used to explain the torsional vibration on a drill string, using a torsional spring-pendulum with damping to model a long slender drill string is not advisable. The drill string should be constrained in the well bore. As an example, appropriate physical and mathematical models of drill string axial and torsional vibrations are recommended.