Oil well bore hole surveying by kinematic navigation
First Claim
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1. Bore hole survey apparatus, comprising:
- an instrumentation pod adapted for travel down a bore hole to be surveyed;
said pod including a rate gyroscope for sensing rotation of the pod substantially about its longitudinal axis along which it travels in the bore hole;
said pod including accelerometer means for sensing the Earth'"'"'s gravity vector with respect to a frame of reference of the pod;
means for lowering said pod in a bore hole and for measuring increments of said lowering; and
computational means connected for receiving signals from said rate gyroscope, said accelerometers and said lowering means, and for calculating therefrom the updated attitude and position of said pod as it is lowered into said bore hole, said computational means being programmed with an algorithm which calculates the updated pod location by performing the steps of;
(a) receiving said signals from said rate gyroscope and calculating therefrom an increment of rotation of the pod around its longitudinal axis (dθ
gy);
(b) receiving said signals from said accelerometer means and calculating therefrom an incremental tilt of the gravity vector from the pod frame of reference (dg);
(c) calculating an incremental rotation of the pod (dθ
) using the formula ##EQU5## (d) calculating from dθ
the updated attitude matrix of the pod and calculating therefrom a unit direction vector (u) which indicates the direction in inertial space of the longitudinal axis of the pod; and
(e) multiplying the unit direction vector by the measured increments of the cable received from said means for lowering and calculating therefrom the updated pod location.
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Abstract
Apparatus and method for the surveying of bore holes, for example, oil wells and the like, to permit accurate three-dimensional mapping thereof, using a single rate gyroscope and an accelerometer package in an instrumentation pod which is lowered into the bore hole. Signals from the accelerometers and the rate gyroscope plus the increments by which the pod is lowered into the well permit continual calculation of pod attitude and updated of pod position at all depths in the hole.
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Citations
11 Claims
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1. Bore hole survey apparatus, comprising:
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an instrumentation pod adapted for travel down a bore hole to be surveyed; said pod including a rate gyroscope for sensing rotation of the pod substantially about its longitudinal axis along which it travels in the bore hole; said pod including accelerometer means for sensing the Earth'"'"'s gravity vector with respect to a frame of reference of the pod; means for lowering said pod in a bore hole and for measuring increments of said lowering; and computational means connected for receiving signals from said rate gyroscope, said accelerometers and said lowering means, and for calculating therefrom the updated attitude and position of said pod as it is lowered into said bore hole, said computational means being programmed with an algorithm which calculates the updated pod location by performing the steps of; (a) receiving said signals from said rate gyroscope and calculating therefrom an increment of rotation of the pod around its longitudinal axis (dθ
gy);(b) receiving said signals from said accelerometer means and calculating therefrom an incremental tilt of the gravity vector from the pod frame of reference (dg); (c) calculating an incremental rotation of the pod (dθ
) using the formula ##EQU5## (d) calculating from dθ
the updated attitude matrix of the pod and calculating therefrom a unit direction vector (u) which indicates the direction in inertial space of the longitudinal axis of the pod; and(e) multiplying the unit direction vector by the measured increments of the cable received from said means for lowering and calculating therefrom the updated pod location. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of surveying a bore hole, comprising the steps of:
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lowering by a known increment an instrumentation pod containing a rate gyroscope and accelerometer means into the bore hole to be surveyed; sensing the Earth'"'"'s gravity vector and any rotation of the pod for increments of lowering of the pod; and calculating and updating the position of the pod for each increment of lowering by the substeps of; (a) calculating an increment of rotation of the pod around its longitudinal axis (dθ
gy);(b) calculating the incremental tilt of the gravity vector from the pod frame of reference (dg); (c) calculating the incremental rotation of the pod (d0);
using the formula ##EQU6## (d) calculating from dθ
the updated attitude matrix of the pod and calculating therefrom a unit direction vector (u) which indicates the direction in inertial space of the longitudinal axis of the pod; and(e) multiplying the unit direction vector by the incremental lowering of the cable and calculating therefrom updated position of the pod. - View Dependent Claims (9, 10, 11)
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Specification