Method and apparatus for precise positioning of a borehole measurement instrument
First Claim
1. A method for use in a downhole tool having a distance measurement device, a feature detection device, and a primary measurement device positioned therein, the method comprising:
- recording in a first log, while the downhole tool is in a borehole, a first plurality of features detected using the feature detection device while the feature detection device and the distance measurement device are being moved with respect to the downhole tool, wherein each of the first plurality of features is recorded with a corresponding position measured using the distance measurement device, wherein the corresponding position of each of the first plurality of features corresponds to a distance measurement relating to an internal position of the feature detection device with respect to the downhole tool when the feature detection device detected the respective plurality of features;
selecting a first feature of the first plurality of features in the first log and identifying the position corresponding to the first feature;
without controllably moving an overall position of the downhole tool in the borehole, moving the feature detection device with respect to the downhole tool based on the identified relative position of the first feature to align the feature detection device relative to the first feature;
taking a first primary measurement using the primary measurement device while the feature detection device is aligned relative to the first feature; and
repeating the steps of recording, selecting, moving, and taking to obtain at least a second primary measurement while the feature detection device is aligned relative to a second feature of a second plurality of features in a second log.
1 Assignment
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Accused Products
Abstract
A system and method for use in a downhole tool having distance measurement, feature detection, and primary measurement devices positioned therein are provided. In one example, the method includes recording a first plurality of features and corresponding positions in a first log using the feature detection device and the distance measurement device, respectively. A first feature of the first plurality of features is selected and the position corresponding to the first feature is identified. The feature detection device is aligned relative to the first feature based on the identified position. A first primary measurement is taken using the primary measurement device while the feature detection device is aligned relative to the first feature. The steps of recording, selecting, moving, and taking are repeated to obtain a second primary measurement while the feature detection device is aligned relative to a second feature of a second plurality of features.
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Citations
22 Claims
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1. A method for use in a downhole tool having a distance measurement device, a feature detection device, and a primary measurement device positioned therein, the method comprising:
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recording in a first log, while the downhole tool is in a borehole, a first plurality of features detected using the feature detection device while the feature detection device and the distance measurement device are being moved with respect to the downhole tool, wherein each of the first plurality of features is recorded with a corresponding position measured using the distance measurement device, wherein the corresponding position of each of the first plurality of features corresponds to a distance measurement relating to an internal position of the feature detection device with respect to the downhole tool when the feature detection device detected the respective plurality of features; selecting a first feature of the first plurality of features in the first log and identifying the position corresponding to the first feature; without controllably moving an overall position of the downhole tool in the borehole, moving the feature detection device with respect to the downhole tool based on the identified relative position of the first feature to align the feature detection device relative to the first feature; taking a first primary measurement using the primary measurement device while the feature detection device is aligned relative to the first feature; and repeating the steps of recording, selecting, moving, and taking to obtain at least a second primary measurement while the feature detection device is aligned relative to a second feature of a second plurality of features in a second log. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for indexing fixed positions in a borehole using a downhole tool comprising:
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selecting at least first and second measurement stations, wherein a distance between the first and second measurement stations is greater than a maximum travel distance of a conveyance mechanism positioned within the downhole tool that moves internally within the downhole tool and with respect to the downhole tool; moving the downhole tool in the borehole to the first measurement station; recording a first data set representing a first plurality of features and a relative position of each of the first plurality of features at the first measurement station with respect to the downhole tool; selecting a first feature from the first data set and, without controllably moving the overall position of the downhole tool in the borehole, moving the conveyance mechanism with respect to the downhole tool to relate the conveyance mechanism to the first feature and taking a first measurement based on the relative position of the first feature; moving the downhole tool in the borehole to the second measurement station; recording a second data set representing a second plurality of features and a relative position of each of the second plurality of features at the second measurement station with respect to the downhole tool; and selecting a second feature from the second data set and, without controllably moving the overall position of the downhole tool in the borehole, moving the conveyance mechanism with respect to the downhole tool to relate the conveyance mechanism to the second feature and taking a second measurement based on the position of the second feature. - View Dependent Claims (13, 14, 15, 16)
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17. A downhole tool comprising:
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a feature detection device configured to detect a plurality of features external to the downhole tool when positioned in a borehole; a primary measurement device configured to measure a value of a defined type; a conveyance mechanism coupled to the feature detection device and the primary measurement device, wherein the conveyance mechanism is configured to controllably move the feature detection device and the primary measurement device with respect to the downhole tool; a distance measuring device configured to measure a distance traveled by the conveyance mechanism with respect to the downhole tool; and computer-executable instructions for controlling the conveyance mechanism to position the primary measurement device relative to a feature of the plurality of features detected by the feature detection device based on a position of the feature as measured by the distance measurement device. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification