Pitfalls in the Use of Discrete Models with Cutting Dynamics for Drill-Strings

Abstract

In this paper, an established 2 degrees-of-freedom drill-string model (one axial, one torsional) is compared against another model consisting of 1-axial-DOF and a continuous torsional formulation. Some application cases considering different operation conditions for a 1200m drill-column are simulated. The results show that the dynamics can differ considerably. This suggests that the 2-DOF approach may be capturing aspects of the dynamics that are neglected in the 2-DOF approach.