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.

The present invention relates to an optical fiber cable (100) including one or more optical fibers (102), one or more tubular structures (104), a sheath (106) surrounding the one or more tubular structures (104) and a plurality of strength members (108) partially embedded in the sheath (106). In particular, each tubular structure (104) has at least one optical fiber. Moreover, the plurality of strength members (108) in the optical fiber cable (100) are n+1, where n is an even integer.

An optical communication cable and related method is provided. The cable includes a cable body and a plurality of optical transmission elements surrounded by the cable body. The cable includes a reinforcement layer surrounding the plurality of optical transmission elements and located between the cable body and the plurality of optical transmission elements. The reinforcement layer includes an outer surface and a channel defined in the outer surface that extends in the longitudinal direction along at least a portion of the length of the cable. The cable includes an elongate strength element extending in the longitudinal direction within the channel.

The present invention discloses a logging encapsulated optical-fiber duct cable and a manufacturing method thereof. The encapsulated optical-fiber duct cable mainly comprises an external encapsulation layer. At least one armor tube is arranged in the encapsulation layer. An optical fiber protective tube is arranged in each armor tube. A filling layer is arranged in a space between the optical fiber protective tube and the armor tube. An optical fiber is arranged in the optical fiber protective tube. The manufacturing method mainly comprises four steps: pavement of the optical fiber and formation of the protective tube, formation of the filling layer, formation of the armor tube and formation of the encapsulation layer. The optical-fiber duct cable of the present invention has the advantages of large length, high strength, good temperature tolerance, small signal transmission loss, high transmission speed and synchronous transmission of multiple signals.

An optical fiber cable includes a jacket and a plurality of stranded core subunits, each core subunit comprising a flexible sheath and a plurality of ribbons arranged in a ribbon group, wherein each ribbon of the plurality of ribbons comprises a plurality of connected fibers such that 50-70% of the cross-sectional area inside the sheath is occupied by the connected fibers. The flexible sheath may be an extruded PVC material that conforms to the shape of the ribbon stack and keeps all of the ribbons acting as a unitary body during bending.

An optical fiber cable includes a core that includes an assembled plurality of optical fibers; an inner sheath that accommodates the core therein, a pair of tension members that are embedded in the inner sheath and that are disposed on opposite sides of the core, and an outer sheath that covers the inner sheath. The inner sheath is formed with a dividing portion that divides an inner peripheral surface and an outer peripheral surface of the inner sheath in a circumferential direction. The dividing portion extends along a longitudinal direction in which the optical fiber cable extends.

An optical fiber cable is composed of an optical fiber core, a tension member, an outer sheath, and so forth. The optical fiber core includes a glass wire and a resin-coated part, which is further coated by a transparent member on its outer periphery. The transparent member is, for example, urethane acrylate, PVC, nylon, and so forth. The transparent member preferably has a total light transmittance, defined by JIS K7361-1, of 60% or higher. The reason is that when the total light transmittance is less than 60%, the color tone of the optical fiber core (transparent member) becomes intense and stands out. Additionally, it is preferable that the total light transmittance of the transparent member is 80% or more.

An indoor cable is composed of an optical fiber core, tension members, an outer sheath, and so forth. The optical fiber core and the tension members are integrated by the outer sheath. The outer sheath is composed of a transparent material. The optical fiber core includes a glass wire and a resin coating (a primary resin layer and a secondary resin layer). The optical fiber core does not have a colored layer that is conventionally formed on the outer periphery of the resin coating layer. That is, the optical fiber core is composed entirely of transparent materials. On both sides of the optical fiber core, separate from the optical fiber core, is arranged a pair of tension members. The tension members are composed of transparent materials.

Described herein are coated optical fibers including an optical fiber portion, wherein the optical fiber portion includes a glass core and cladding section that is configured to possesses certain mode-field diameters and effective areas, and a coating portion including a primary and secondary coating, wherein the primary coating is the cured product of a composition that possesses specified liquid glass transition temperatures, such as below −82° C., and/or a viscosity ratios, such as between 25° C. and 85° C., of less than 13.9. Also described are radiation curable coating compositions possessing reduced thermal sensitivity, methods of coating such radiation curable coating compositions to form coated optical fibers, and optical fiber cables comprising the coated optical fibers and/or radiation curable coating compositions elsewhere described.

A method of removing a tight buffer coating from an optical fiber involves positioning an end section of the optical fiber next to an end of a tube, with at least a portion of the the end section including a primary coating and the tight buffer coating. The tube has an inner diameter greater than an outer diameter of the primary coating and an outer diameter less than an outer diameter of the tight buffer coating. The method also involves applying energy to heat the tight buffer coating, inserting the end section of the optical fiber into the tube so that the tight buffer coating contacts the end of the tube, and advancing the end section of the optical fiber along the tube. The tube removes the tight buffer coating from the primary coating as the end section of the optical fiber is advanced.