Fiber optic distributed vibration sensing with directional sensitivity
First Claim
1. A method of determining velocity components of an acoustic wavefield incident on a distributed fiber optic sensor, comprising:
- providing a distributed fiber optic sensor that is configured to provide a distributed response to an incident acoustic wavefield, the fiber optic sensor including fiber that is spatially distributed in planes of a three-dimensional volume having three orthogonal axes, the fiber including;
a first fiber pattern that is spatially distributed within a first plane of the three-dimensional volume; and
,a second fiber pattern that is spatially distributed within a second plane of the volume that is non-parallel to the first plane;
launching optical energy into the fiber optic sensor to obtain individual responses from each of the first fiber pattern and the second fiber pattern to the incident acoustic wavefield, andprocessing the individual responses to determine separate velocity components of the acoustic wavefield relative to orthogonal axes of the three-dimensional volume.
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Abstract
Methods for determining separate velocity components of an acoustic wavefield that are incident on a distributed fiber optic sensor are disclosed. A fiber optic sensor includes fiber that is spatially distributed in non-parallel planes of a three-dimensional volume having three orthogonal axes. The fiber includes a first fiber pattern that is spatially distributed within a first plane of the three-dimensional volume, and a second fiber pattern that is spatially distributed within a second plane of the volume. The fiber patterns are interrogated separately by a distributed fiber optic interrogation system. The individual responses from each pattern are combined and processed to determine separate velocity components of the acoustic wavefield relative to the orthogonal axes of the three-dimensional volume.
34 Citations
27 Claims
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1. A method of determining velocity components of an acoustic wavefield incident on a distributed fiber optic sensor, comprising:
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providing a distributed fiber optic sensor that is configured to provide a distributed response to an incident acoustic wavefield, the fiber optic sensor including fiber that is spatially distributed in planes of a three-dimensional volume having three orthogonal axes, the fiber including; a first fiber pattern that is spatially distributed within a first plane of the three-dimensional volume; and
,a second fiber pattern that is spatially distributed within a second plane of the volume that is non-parallel to the first plane; launching optical energy into the fiber optic sensor to obtain individual responses from each of the first fiber pattern and the second fiber pattern to the incident acoustic wavefield, and processing the individual responses to determine separate velocity components of the acoustic wavefield relative to orthogonal axes of the three-dimensional volume. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of determining velocity components of an acoustic wavefield incident on a distributed fiber optic sensor, comprising:
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providing a distributed fiber optic sensor that is configured to provide a distributed response to an incident acoustic wavefield, the fiber optic sensor including fiber that is spatially distributed in a three-dimensional volume having three orthogonal axes, the fiber including; a first fiber pattern that is helically wound about a tubular support structure; and a second fiber pattern that is spatially distributed within a first plane of the three-dimensional volume; launching optical energy into the fiber optic sensor to obtain individual responses from each of the first fiber pattern and the second fiber pattern to the incident acoustic wavefield, and processing the individual responses to determine separate velocity components of the acoustic wavefield relative to the orthogonal axes of the three-dimensional volume. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of determining direction of travel of an acoustic wavefield, comprising:
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providing a fiber optic sensor that is configured to provide a distributed response to an incident acoustic wavefield; launching optical energy into the fiber optic sensor and detecting backscatter generated by the fiber sensor in response to the launched optical energy; acquiring, from the detected backscatter, a data set representing strain imparted on the fiber optic sensor by the incident acoustic wavefield; determining from the data set, a spatial gradient of the strain; determining a polarity mask based on the spatial gradient; and applying the polarity mask to the data set to determine direction of travel of the acoustic wavefield. - View Dependent Claims (24, 25)
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26. A method, comprising:
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providing a distributed fiber optic sensor that is configured to provide a distributed response to an incident acoustic wavefield, the fiber optic sensor including fiber that is spatially distributed in non-parallel planes of a three-dimensional volume having three orthogonal axes, the fiber including; a first helical pattern wound about a mandrel in a first direction; a second helical pattern wound about the mandrel in a second direction opposite the first direction; launching optical energy into the fiber optic sensor to obtain individual responses from each of the first fiber pattern and the second fiber pattern to the incident acoustic wavefield, and processing the individual responses to determine a torsional component of the acoustic wavefield. - View Dependent Claims (27)
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Specification