Borehole orientation detection system employing polarized radiation
First Claim
1. In a borehole survey instrument having a probe suspended from a cable to traverse a borehole, the probe having a longitudinal axis and being rotatable about said longitudinal axis as it traverses the borehole, an improved means for determining the probe orientation about its longitudinal axis, comprising:
- a source of polarized electromagnetic radiation in said probe generating a polarized signal which has an axis of polarization transverse to the longitudinal axis of the probe and in fixed relation to the probe;
a signal conduit for conducting said polarized signal to the surface; and
means for detecting the plane of polarization of the signal received from said conduit.
1 Assignment
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Accused Products
Abstract
A borehole survey instrument has a probe with a polarized light system for transmitting a signal representing the angular orientation of the probe to the surface. Light from a source in the probe is directed through a polarizing filter with an axis of polarization orthogonal to the longitudinal axis of the probe. The polarized light beam is transmitted to the surface through an optical fiber light conduit. The angle of polarization is detected with a rotating polarizing filter and provides a measure of the probe orientation. In surveying a borehole, azimuth is determined from inclinometer measurements. The probe orientation in vertical sections of the borehole is measured by the polarized light system. Two measures of borehole azimuth are combined, providing an improved measure of azimuth in boreholes near vertical and near horizontal.
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Citations
11 Claims
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1. In a borehole survey instrument having a probe suspended from a cable to traverse a borehole, the probe having a longitudinal axis and being rotatable about said longitudinal axis as it traverses the borehole, an improved means for determining the probe orientation about its longitudinal axis, comprising:
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a source of polarized electromagnetic radiation in said probe generating a polarized signal which has an axis of polarization transverse to the longitudinal axis of the probe and in fixed relation to the probe; a signal conduit for conducting said polarized signal to the surface; and means for detecting the plane of polarization of the signal received from said conduit. - View Dependent Claims (2, 3, 4, 8, 9, 10, 11)
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5. A borehole survey probe comprising:
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a housing to traverse the borehole, the housing having a longitudinal axis and being randomly rotatable about said longitudinal axis as the housing traverses the borehole; an inclinometer in said housing; and a source of polarized electromagnetic radiation fixed to said housing generating a polarized signal having an axis of polarization orthogonal to the longitudinal axis of the housing, the axis polarization of the signal providing a measure of the orientation of the housing as a reference for said inclinometer. - View Dependent Claims (6, 7)
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Specification