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 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 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: 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: 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: 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: 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 sensor for sensing the pressure of a first fluid is provided. In one embodiment, sensor for sensing the pressure of a first fluid includes a fiber optic based sensing element disposed in a housing. A buffer fluid is disposed in the housing and is in fluid communication with the sensing element. A pressure transmitter is coupled to the housing for maintaining a predefined relationship between pressures of the first fluid and buffer fluid. A connector assembly is coupled to the housing and is coupled by an optical fiber is the sensing element. The sensor having a connector assembly is suitable for use in harsh conditions, such as within oil and gas well applications.

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.

Abstract: A fiber optic Bragg grating pressure sensor particularly suited for measuring ambient pressure of a fluid includes a pressuring detecting device 12 such as a glass element whose elastic deformation is proportional to applied pressure. An optical fiber 28 with an integral first grating 33 is wrapped at least once around the device and has at least a portion of its length fused to the device 12 such that elastic deformation of the device 12 generates a corresponding axial strain in the fiber 28 and/or the grating 33 and thus a corresponding change of the fiber length and/or characteristic reflectance wavelength of the grating 33. A second grating 35 may be formed near the pressure detecting device 12 so as to sense ambient temperature but not be affected by deformation of the device 12 for temperature compensation.

Abstract: An accelerometer has a main body in combination with one or more Bragg grating sensors respectively arranged along one or more axes. The main body has a mass that responds to an acceleration, for providing a force having a component in one or more axes. The Bragg grating sensor means responds to the force, and further responds to an optical signal, for providing a Bragg grating sensor signal containing information about the acceleration respectively in one or more axes. The one or more axes may include orthogonal axes such as the X, Y and Z Euclidian axes. In one embodiment, the main body includes a proof mass and a pair of flexure disks, each having an inner ring, an outer ring, and radial splines connecting the inner ring and the outer ring. The proof mass is slidably arranged between the flexure disks. The Bragg grating means has an optical fiber and a Bragg grating sensor arranged therein. A first end of the Bragg grating sensor is fixedly coupled by a first ferrule to the proof mass.

Abstract: Lengths of coiled tubing have sensor carrier elements mounted therebetween such that a plurality of sensor carrier elements are positioned along a length of coiled tubing. Each sensor carrier element carriers a sensor implemented with one or more intrinsic fiber optic sensor elements positioned therein for measuring one or more parameters in an environment. The intrinsic fiber optic sensor elements are multiplexed on one or more optical fibers along the length of the coiled tubing thereby forming a length of coiled tubing having a plurality of spaced apart sensors. The optical fiber or fibers positioned along the length of the coiled tubing are positioned in a fiber carrier which protects the fiber or fibers from the harsh environment. The fiber carrier may be interconnected to each of the sensors to isolate the fibers from the harsh environment.

Abstract: A method and apparatus for nuclear logging, and in particular, neutron porosity logging is presented. In accordance with the present invention, a pair of spaced lithium detectors, preferably Li.sup.6 I crystal or Li.sup.6 doped glass are used to detect neutrons emitted from a borehole formation being logged. In addition, novel data processing is used to strip the gamma-ray peak from the spectrum developed by the lithium detectors.