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Active signal conditioning circuitry for well logging and monitoring while drilling nuclear magnetic resonance spectrometers

  • US 6,603,309 B2
  • Filed: 05/21/2001
  • Issued: 08/05/2003
  • Est. Priority Date: 05/21/2001
  • Status: Expired due to Term
First Claim
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1. A method for investigating properties of an earth formation with a nuclear magnetic resonance (NMR) apparatus traversed by a borehole, comprising the steps for:

  • traversing a borehole adjacent a formation with a nuclear magnetic resonance (NMR) probe having a transmitter circuit for transmitting a radio frequency excitation pulse from an antenna and a receiving circuit for receiving voltages induced by precession of nuclei in the formation;

    inducing a static magnetic field in the formation from a permanent magnet in the NMR probe;

    activating a floating attenuator before transmission of the RF pulse; and

    transmitting a radio frequency pulse from the antenna in the NMR probe thereby inducing a time varying magnetic field in the formation, the pulse having a fixed duration.

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