Abstract: Embodiments of the present invention generally relate to methods and apparatuses for gripping and shearing a downhole cable. In one embodiment, a line cutter mandrel includes: a tubular mandrel; a pocket disposed along an outer surface of the mandrel and longitudinally coupled to the mandrel; a channel disposed through the pocket for receiving a cable; and a line cutter. The line cutter includes a blade, is operable to engage an outer surface of the cable in a gripping position, is operable to at least substantially sever the cable with the blade in a cutting position, and is operable from the gripping position to the cutting position by relative longitudinal movement between the cable and the pocket.

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 distributed temperature sensing (DTS) include marking one or more points at known locations along a waveguide or fiber of a distributed temperature sensing (DTS) system and applying position information from such marked locations to DTS measurements. A Bragg grating in the waveguide or fiber may provide a discrete marker for identification of the position information. Application of the position information from such marked locations to the DTS measurements avoids ambiguous interpretations of other inherent features to assess location and enables data analysis referenced by the known locations to correlate the DTS measurements in space.

Abstract: Embodiments of the present invention generally relate to methods and apparatuses for gripping and shearing a downhole cable. In one embodiment, a line cutter mandrel includes: a tubular mandrel; a pocket disposed along an outer surface of the mandrel and longitudinally coupled to the mandrel; a channel disposed through the pocket for receiving a cable; and a line cutter. The line cutter includes a blade, is operable to engage an outer surface of the cable in a gripping position, is operable to at least substantially sever the cable with the blade in a cutting position, and is operable from the gripping position to the cutting position by relative longitudinal movement between the cable and the pocket.

Abstract: An optical waveguide feedthrough assembly passes at least one optical waveguide through a bulk head, a sensor wall, or other feedthrough member. The optical waveguide feedthrough assembly comprises a cane-based optical waveguide that forms a glass plug sealingly disposed in a feedthrough housing. A seal fills an annular space between the glass plug and the housing. The seal may be energized by a fluid pressure in the housing to establish sealing engagement. Further, the seal may provide bidirectional sealing. The feedthrough assembly is operable in high temperature and high pressure environments.

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: Methods and apparatus for distributed temperature sensing (DTS) include marking one or more points at known locations along a waveguide or fiber of a distributed temperature sensing (DTS) system and applying position information from such marked locations to DTS measurements. A Bragg grating in the waveguide or fiber may provide a discrete marker for identification of the position information. Application of the position information from such marked locations to the DTS measurements avoids ambiguous interpretations of other inherent features to assess location and enables data analysis referenced by the known locations to correlate the DTS measurements in space.

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 waveguide feedthrough assembly passes at least one optical waveguide through a bulk head, a sensor wall, or other feedthrough member. The optical waveguide feedthrough assembly comprises a cane-based optical waveguide that forms a glass plug sealingly disposed in a feedthrough housing. A seal fills an annular space between the glass plug and the housing. The seal may be energized by a fluid pressure in the housing to establish sealing engagement. Further, the seal may provide bidirectional sealing. The feedthrough assembly is operable in high temperature and high pressure environments.

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: Method and apparatus for feeding on optical waveguide through a partition device, such as a wellhead outlet are disclosed. For some embodiments, the wellhead outlet includes a first chamber having a first port, a second chamber having a second port connected by a path to the first port for feeding an optical waveguide through to the first chamber, and a strain relief member coupled with the first chamber to limit motion of the optical waveguide at or near the first port. The strain relief member can be a rigid curved tube coupled to the first port and/or a fiber management member providing one or more fiber retention pathways.

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 method and device for pressure sensing using an optical fiber having a core, a cladding and a Bragg grating imparted in the core for at least partially reflecting an optical signal at a characteristic wavelength. The cladding has two variation regions located on opposite sides of the Bragg grating to allow attachment mechanisms to be disposed against the optical fiber. The attachment mechanisms are mounted to a pressure sensitive structure so as to allow the characteristic wavelength to change according to pressure in an environment. In particular, the variation region has a diameter different from the cladding diameter, and the attachment mechanism comprises a ferrule including a front portion having a profile substantially corresponding to at least a portion of the diameter of the variation region and a butting mechanism which holds the ferrule against the optical fiber.

Abstract: A method and device for tuning an optical device including an optical fiber having a core, a cladding and a Bragg grating imparted in the core to partially reflect an optical signal at a reflection wavelength characteristic of the spacing of the Bragg grating. The cladding has two variation regions located on opposite sides of the Bragg grating to allow attachment mechanisms to be disposed against the optical fiber. The attachment mechanisms are mounted to a frame so as to allow the spacing of the Bragg grating to be changed by an actuator which tunes the reflection wavelength. In particular, the variation region has a diameter different from the cladding diameter, and the attachment mechanism comprises a ferrule including a front portion having a profile substantially corresponding to diameter of the variation region and a butting mechanism butting the ferrule against the optical fiber.

Abstract: A fused tension-based fiber grating pressure sensor includes an optical fiber having a Bragg grating impressed therein. The fiber is fused to tubes on opposite sides of the grating and an outer tube is fused to the tubes to form a chamber. The tubes and fiber may be made of glass. Light is incident on the grating and light is reflected from the grating at a reflection wavelength &lgr;1. The grating is initially placed in tension as the pressure P increases, the tension on the grating reduced and the reflection wavelength shifts accordingly. A temperature grating may be used to measure temperature and allow for a temperature-corrected pressure measurement.

Abstract: A method and device for tuning an optical device including an optical fiber having a core, a cladding and a Bragg grating imparted in the core to partially reflect an optical signal at a reflection wavelength characteristic of the spacing of the Bragg grating. The cladding has two variation regions located on opposite sides of the Bragg grating to allow attachment mechanisms to be disposed against the optical fiber. The attachment mechanisms are mounted to a frame so as to allow the spacing of the Bragg grating to be changed by an actuator which tunes the reflection wavelength. In particular, the variation region has a diameter different from the cladding diameter, and the attachment mechanism comprises a ferrule including a front portion having a profile substantially corresponding to diameter of the variation region and a butting mechanism butting the ferrule against the optical fiber.

Abstract: A method and device for pressure sensing using an optical fiber having a core, a cladding and a Bragg grating imparted in the core for at least partially reflecting an optical signal at a characteristic wavelength. The cladding has two variation regions located on opposite sides of the Bragg grating to allow attachment mechanisms to be disposed against the optical fiber. The attachment mechanisms are mounted to a pressure sensitive structure so as to allow the characteristic wavelength to change according to pressure in an environment. In particular, the variation region has a diameter different from the cladding diameter, and the attachment mechanism comprises a ferrule including a front portion having a profile substantially corresponding to at least a portion of the diameter of the variation region and a butting mechanism which holds the ferrule against the optical fiber.

Abstract: A creep-resistant optical fiber attachment includes an optical fiber 10, having a cladding 12 and a core 14, having a variation region 16 (expanded or recessed) of an outer dimension on of the cladding and a structure, such as a ferrule 30, disposed against least a portion of the variation region 16. The fiber 10 is held in tension against the ferrule and the ferrule 30 has a size and shape that mechanically locks the ferrule 30 to the variation 16, thereby holding the fiber 10 in tension against the ferrule 30 with minimal relative movement (or creep) in at least one axail direction between the fiber 10 and the ferrule 30. The ferrule 30 may be attached to or part of a larger structure, such as a housing. The variation 16 and the ferrule 30 may have various different shapes and sizes. There may also be a buffer layer 18 between the cladding 12 and the ferrule 30 to protect the fiber 10 and/or to help secure the ferrule 30 to the fiber 10 to minimize creep.