Abstract: An optical transducer is provided. A “measuring” portion of the transducer may be exposed to a high pressure and fluids when the optical transducer is deployed (e.g., in a wellbore or other industrial setting). The transducer may include an optical waveguide with a first portion that forms a first seal that isolates an “instrumentation” portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed. The transducer may also include a second seal with a “stack” of material elements that contact a second portion of the optical waveguide to also isolate the instrumentation portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed.

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.

Abstract: Small profile apparatus for pressure and/or temperature sensing within a wellbore are provided. The apparatus may include optical sensing assemblies designed for inclusion in traditional or coiled production tubing deployments and suitable for use in high pressure, high temperature environments. One example assembly generally includes a housing having a divider for separating a first volume from a second volume inside the housing, a compressible element disposed in the first volume, wherein a first end of the compressible element is coupled to the divider and a second of the compressible element is sealed, and a large diameter optical waveguide disposed in an internal volume of the compressible element. The waveguide typically includes a first portion with a first grating and a second portion with a second grating, wherein the first portion has a greater outer diameter than the second portion.

Abstract: Embodiments of the present invention provide methods and apparatus for cables having one or more fibers that may function as a sensing device within a wellbore, wherein the fibers do not adhere to each other or to an inner wall of the cable during a high temperature operation, such as in a thermal recovery operation that may last over 30 days.

Abstract: An optical transducer is provided. A “measuring” portion of the transducer may be exposed to a high pressure and fluids when the optical transducer is deployed (e.g., in a wellbore or other industrial setting). The transducer may include an optical waveguide with a first portion that forms a first seal that isolates an “instrumentation” portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed. The transducer may also include a second seal with a “stack” of material elements that contact a second portion of the optical waveguide to also isolate the instrumentation portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed.

Abstract: Methods and apparatus for interrogating sets of optical elements having characteristic wavelengths spanning a sweep range while avoiding overlapping reflections from the different sets when performing a wavelength sweep are provided. One example method generally includes introducing a pulse of light, by an optical source, into an optical waveguide to interrogate at least first and second sets of optical elements, wherein the optical elements within each set have different characteristic wavelengths and wherein the first and second sets are separated in time such that a first time window over which light is reflected from the optical elements in the first set and reaches a receiver does not overlap with a second time window over which light is reflected from the optical elements in the second set and reaches the receiver; and processing the reflected light to determine one or more parameters corresponding to the optical elements.

Abstract: Embodiments of the present invention provide methods and apparatus for cables having one or more fibers that may function as a sensing device within a wellbore, wherein the fibers do not adhere to each other or to an inner wall of the cable during a high temperature operation, such as in a thermal recovery operation that may last over 30 days.

Abstract: Methods and apparatus enable monitoring conditions in a well-bore using multiple cane-based sensors. The apparatus includes an array of cane-based Bragg grating sensors located in a single conduit for use in the well-bore. For some embodiments, each sensor is located at a different linear location along the conduit allowing for increased monitoring locations along the conduit.

Abstract: A sensing device is used for measuring physical characteristics. The sensing device may include an optical fiber disposed in a tube. The optical fiber may have a section containing a fiber Bragg grating (FBG) sensor. A support member may be coupled to the ends of the section, such that the section includes a length greater than a length of the portion of the support member disposed between the ends of the section. The support member is configured to isolate the FBG sensor from strain in the optical fiber.

Abstract: Methods and apparatus enable monitoring conditions in a well-bore using multiple cane-based sensors. The apparatus includes an array of cane-based Bragg grating sensors located in a single conduit for use in the well-bore. For some embodiments, each sensor is located at a different linear location along the conduit allowing for increased monitoring locations along the conduit.

Abstract: Methods and apparatus enable monitoring conditions in a well-bore using multiple cane-based sensors. The apparatus includes an array of cane-based Bragg grating sensors located in a single conduit for use in the well-bore. For some embodiments, each sensor is located at a different linear location along the conduit allowing for increased monitoring locations along the conduit.

Abstract: Methods and apparatus enable monitoring conditions in a well-bore using multiple cane-based sensors. The apparatus includes an array of cane-based Bragg grating sensors located in a single conduit for use in the well-bore. For some embodiments, each sensor is located at a different linear location along the conduit allowing for increased monitoring locations along the conduit.

Abstract: An optical transducer is provided. A “measuring” portion of the transducer may be exposed to a high pressure and fluids when the optical transducer is deployed (e.g., in a wellbore or other industrial setting). The transducer may include an optical waveguide with a first portion that forms a first seal that isolates an “instrumentation” portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed. The transducer may also include a second seal with a “stack” of material elements that contact a second portion of the optical waveguide to also isolate the instrumentation portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed.

Abstract: An optical fiber feedthrough assembly includes a glass plug disposed in a recess of a feedthrough housing. The glass plug may define a large-diameter, cane-based, waveguide sealed within the recess in the housing and providing optical communication through the housing. Sealing occurs with respect to the housing at or around the glass plug of an optical waveguide element passing through the housing by braze sealing to the glass plug and/or embedding the glass plug in a polymer bonded with the plug to form a molded body that is sealed in the housing by, for example, compression mounting of the molded body or providing a sealing element around the molded body.

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.

Abstract: An optical fiber feedthrough assembly includes a glass plug disposed in a recess of a feedthrough housing. The glass plug may define a large-diameter, cane-based, waveguide sealed within the recess in the housing and providing optical communication through the housing. Sealing occurs with respect to the housing at or around the glass plug of an optical waveguide element passing through the housing by braze sealing to the glass plug and/or embedding the glass plug in a polymer bonded with the plug to form a molded body that is sealed in the housing by, for example, compression mounting of the molded body or providing a sealing element around the molded body.

Abstract: Purging interior regions of a cable reduces or prevents hydrogen darkening of an optical fiber located in the cable. While hydrogen may permeate through an outer surface of the cable, fluid circulating through the cable purges the hydrogen from within the cable. This circulation of the fluid occurs between an inner tube containing the fiber and an outer tube surrounding the inner tube.

Abstract: Purging interior regions of a cable reduces or prevents hydrogen darkening of an optical fiber located in the cable. While hydrogen may permeate through an outer surface of the cable, fluid circulating through the cable purges the hydrogen from within the cable. This circulation of the fluid occurs between an inner tube containing the fiber and an outer tube surrounding the inner tube.

Abstract: An optical fiber feedthrough assembly includes a glass plug disposed in a recess of a feedthrough housing. The glass plug may define a large-diameter, cane-based, waveguide sealed within the recess in the housing and providing optical communication through the housing. Sealing occurs with respect to the housing at or around the glass plug of an optical waveguide element passing through the housing by braze sealing to the glass plug and/or embedding the glass plug in a polymer bonded with the plug to form a molded body that is sealed in the housing by, for example, compression mounting of the molded body or providing a sealing element around the molded body.

Abstract: Embodiments of the present invention provide methods and apparatus for cables having one or more fibers that may function as a sensing device within a wellbore, wherein the fibers do not adhere to each other or to an inner wall of the cable during a high temperature operation, such as in a thermal recovery operation that may last over 30 days.