Reduction of motion artifacts in NMR

US7180287B2 · kind B2 · utility

Assignee

• Baker Hughes Holdings LLC · US

Inventors

• Peter Rottengatter · Celle, DE
• Holger Thern · Hannover, DE
• Radu Fechete · Iernut, RO
• Martin Blanz · Culham, GB
• Thomas Kruspe · Braunschweig, DE

Key dates

• Filing date: May 5, 2004
• Grant date: Feb 20, 2007
• Expiry date: May 5, 2024

Classification

• Technology area (CPC G): Physics
• CPC primary: G01V3/32
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

NMR spin echo signals, acquired on a MWD logging tool, are susceptible to errors magnetic flux density has a gradient and the magnet on the logging tool is moving relative to the earth. The errors can be corrected by having the excitation pulse cover a smaller or a larger volume than the refocusing pulses. Correction may also be made by selective saturation, or by echo averaging.