Open Access

ARTICLE

An Improved Model to Characterize Drill-String Vibrations in Rotary Drilling Applications

by Yong Wang, Hongjian Ni^*, Ruihe Wang, Shubin Liu

School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, 266580, China

* Corresponding Author: Hongjian Ni. Email:

(This article belongs to the Special Issue: Dynamics and Materials Processing in Petroleum Engineering)

Fluid Dynamics & Materials Processing 2022, 18(5), 1263-1273. https://doi.org/10.32604/fdmp.2022.020405

Received 21 November 2021; Accepted 13 December 2021; Issue published 27 May 2022

Abstract

A specific model is elaborated for stick-slip and bit-bounce vibrations, which are dangerous dynamic phenomena typically encountered in the context of rotary drilling applications. Such a model takes into account two coupled degrees of freedom of drill-string vibrations. Moreover, it assumes a state-dependent time delay and a viscous damping for both the axial and torsional vibrations and relies on a sawtooth function to account for the cutting force fluctuation. In the frame of this theoretical approach, the influence of rock brittleness on the stability of the drill string is calculated via direct integration of the model equations. The results show that the rock brittleness has a great influence on the rotational speed and bit depth.

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Keywords

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