Fiber optic cable for distributed acoustic sensing with increased acoustic sensitivity
First Claim
Patent Images
1. A fiber optic cable used for distributed acoustic sensing (DAS), comprising:
- an outer tube;
an inner tube surrounded by the outer tube; and
one or more optical fibers surrounded by the inner tube, wherein the one or more optical fibers have increased acoustic sensitivity compared to a standard optical fiber, wherein at least one of the one or more optical fibers have a smaller diameter compared to the standard optical fiber, and wherein, upon application of pressures created by acoustic waves, the smaller diameter provides for increased response of the fibers when compared to the standard optical fiber.
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Abstract
Methods and apparatus for performing Distributed Acoustic Sensing (DAS) using fiber optics with increased acoustic sensitivity are provided. Acoustic sensing of a wellbore, pipeline, or other conduit/tube based on DAS may have increased acoustic sensitivity through fiber optic cable design and/or increasing the Rayleigh backscatter property of a fiber'"'"'s optical core. Some embodiments may utilize a resonant sensor mechanism with a high Q coupled to the DAS device for increased acoustic sensitivity.
52 Citations
40 Claims
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1. A fiber optic cable used for distributed acoustic sensing (DAS), comprising:
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an outer tube; an inner tube surrounded by the outer tube; and one or more optical fibers surrounded by the inner tube, wherein the one or more optical fibers have increased acoustic sensitivity compared to a standard optical fiber, wherein at least one of the one or more optical fibers have a smaller diameter compared to the standard optical fiber, and wherein, upon application of pressures created by acoustic waves, the smaller diameter provides for increased response of the fibers when compared to the standard optical fiber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A fiber optic cable used for distributed acoustic sensing (DAS), comprising:
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an outer tube comprising one or more slotted holes in a body of the outer tube; an inner tube surrounded by the outer tube; and one or more optical fibers surrounded by the inner tube. - View Dependent Claims (10, 11)
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12. A fiber optic cable used for distributed acoustic sensing (DAS), comprising:
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one or more sensing regions along a length of the cable having a first acoustic sensitivity; and one or more segments having a second acoustic sensitivity, connecting the one or more sensing regions, wherein the first acoustic sensitivity is greater than the second acoustic sensitivity. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method, comprising:
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providing a fiber optic cable disposed along a length of a conduit, wherein the fiber optic cable comprises; an outer tube comprising one or more slotted holes in a body of the outer tube; an inner tube surrounded by the outer tube; and one or more optical fibers surrounded by the inner tube; and performing distributed acoustic sensing (DAS) along the length of the conduit by receiving acoustic signals using the fiber optic cable. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification