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Method for improving wellbore survey accuracy and placement

  • US 9,297,249 B2
  • Filed: 06/20/2012
  • Issued: 03/29/2016
  • Est. Priority Date: 06/29/2011
  • Status: Expired due to Fees
First Claim
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1. A surveying method comprising:

  • (a) using a proton magnetometer to scan a prospective area and identify a magnetically clean surface location;

    (b) obtaining a first and second global positioning measurements at corresponding first and second surface locations, the first surface location being the magnetically clean surface location identified;

    (c) processing the first and second global positioning measurements obtained to determine a reference direction between the first and second surface locations;

    (d) aligning one axis of a tri-axial magnetic field sensor with the reference direction;

    (e) rotating the magnetic field sensor about the axis aligned with the reference direction;

    (f) measuring a total magnetic force of the Earth at the first surface location while rotating the magnetic field sensor;

    (g) selecting a tool face angle of the magnetic field sensor at which the total magnetic force measured is substantially equal to a total magnetic force value for the first surface location obtained using the proton magnetometer;

    (h) measuring a magnetic field vector of the Earth at the first surface location using the magnetic field sensor oriented at the toolface angle selected; and

    (i) processing the reference direction obtained and the magnetic field vector of the Earth measured to determine at least one of a magnetic declination and a magnetic inclination of the Earth'"'"'s magnetic field.

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