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Wellbore inertial directional surveying system

  • US 4,987,684 A
  • Filed: 09/08/1982
  • Issued: 01/29/1991
  • Est. Priority Date: 09/08/1982
  • Status: Expired due to Fees
First Claim
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1. A borehole survey apparatus comprising:

  • a housing;

    means for selectively moving and stopping said housing along a borehole, said housing being subjected to angular rotations as a result of this movement;

    angular measurement means, including a plurality of gyroscopes supported in said housing, for measuring the angular rate of rotation of said housing and producing angular signals indicative thereof;

    acceleration measurement means, including a plurality of accelerometers mounted in said housing, for measuring inertial accelerations applied to said housing and producing acceleration signals indicative thereof;

    single gimbal platform assembly means contained within said housing for supporting all said gyroscopes and said accelerometers, said platform assembly means having only a single axis of rotation aligned with said housing;

    servo means responsive to said angular signals for preventing rotation of said platform assembly means relative to said borehole while said housing is rotating; and

    computing means forcalculating the position of said housing within said borehole from said angular and acceleration signals and producing position information indicative thereof; and

    estimating system errors using Kalman estimation techniques while said housing is stopped; and

    modifying said position information to compensate for said estimated system errors, said position information forming a survey of said borehole.

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