Method to mitigate bit induced vibrations by intentionally modifying mode shapes of drill strings by mass or stiffness changes

US9976405B2 · kind B2 · utility

Assignee

• Baker Hughes, a GE company, LLC · US

Inventors

• Andreas Hohl · Hannover, DE
• Mathias Tergeist · Celle, DE
• Hatem Oueslati · Lattes, FR
• Christian Herbig · Sulingen, DE
• Jayesh Jain · Diemelstraße, US
• Hanno Reckmann · Wathlingen, DE
• Lance A. Endres · Spring, US

Key dates

• Filing date: Nov 1, 2013
• Grant date: May 22, 2018
• Expiry date: Oct 5, 2036

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F30/17
• WIPO field: Civil engineering
• WIPO sector: Other fields

Abstract

A method for reducing drill tubular vibrations includes: constructing a mathematical model the drill tubular having mass distribution, material stiffness and material damping; constructing an equation of motion of the drill tubular in one of a time domain and frequency domain; transforming the equation of motion into a modal domain equation of motion to provide a mode shape of the drill tubular at an eigenfrequency, the mode shape providing an amplitude at a position along the drill tubular; comparing the amplitude at the position along the drill tubular to a threshold amplitude value; modifying at least one of the mass distribution, material stiffness and material damping if the amplitude exceeds the threshold value; and iterating the above step until at least one of the amplitude of the latest mode shape at the position is less than or equal to the threshold amplitude value and a predetermined constraint limits the modifying.