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Reducing error contributions to gyroscopic measurements from a wellbore survey system

  • US 8,065,087 B2
  • Filed: 01/30/2009
  • Issued: 11/22/2011
  • Est. Priority Date: 01/30/2009
  • Status: Active Grant
First Claim
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1. A method of reducing gravity-dependent error contributions to gyroscopic measurements, the method comprising:

  • providing a survey system within a portion of a wellbore, the survey system comprising;

    a first gyroscopic sensor adapted to generate measurement signals indicative of at least one component of the Earth'"'"'s rotation substantially perpendicular to the portion of the wellbore; and

    a second gyroscopic sensor adapted to generate measurement signals indicative of a component of the Earth'"'"'s rotation substantially parallel to the portion of the wellbore;

    generating a first set of measurement signals indicative of the at least one component of the Earth'"'"'s rotation substantially perpendicular to the portion of the wellbore using the first gyroscopic sensor while the first gyroscopic sensor is in a corresponding first set of four orientations relative to the wellbore;

    generating a second set of measurement signals indicative of the component of the Earth'"'"'s rotation substantially parallel to the portion of the wellbore using the second gyroscopic sensor while the second gyroscopic sensor is in a corresponding second set of four orientations relative to the wellbore;

    calculating information regarding a measurement bias to the measurement signals from the first gyroscopic sensor using the measurement signals from the first gyroscopic sensor in two orientations of the first set of four orientations;

    calculating information regarding a measurement bias to the measurement signals from the second gyroscopic sensor using the measurement signals from the second gyroscopic sensor in two orientations of the second set of four orientations;

    calculating information regarding a quadrature bias to the measurement signals from the first gyroscopic sensor using the first set of measurement signals in the corresponding first set of four orientations; and

    calculating information regarding a quadrature bias to the measurement signals from the second gyroscopic sensor using the second set of measurement signals in the corresponding second set of four orientations.

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