Methods and apparatus to control the acoustic properties of optical cables used as in-well oil and gas probes for acoustic monitoring, such as distributed acoustic sensing (DAS). One example aspect provides a solid path for the acoustic wave to propagate from an outside armor layer of the cable to the sensing optical waveguide embedded therein. Another example aspect offers ways to spatially dispose the optical sensing elements to create response delays indicative of the propagation speed and/or direction of an acoustic wave. Yet another example aspect provides ways to utilize additional spectral interrogation to increase ultimate spatial resolution. Yet another example aspect provides ways to locally vary the acoustic properties along the length of the cable.

The present invention relates to an optical fiber cable (200) with a different binder pitch comprising a plurality of tubes (204) with one or more optical transmission elements (202), a first binder (208) and a second binder (210) wound around the plurality of tubes (204) helically. The first lay length of the first binder (208) is different than a second lay length of the second binder (210) and a lay ratio of the first lay length to the second lay length is equal to or more than 1.2. And the difference between a first stranding angle and a second stranding angle of the first binder (208) and the second binder (210) respectively is greater than or equal to 5 degrees.

An optical fiber carrying structure and a method of making are disclosed. The structure comprises a central core extending from a first end to a second end, and subunits wound around a portion of the central core. The subunits include one or more optical fiber subunits having at least one optical fiber, a connector is attached to an end of the optical fiber subunit, and a filler rod is coupled to the optical fiber subunit.

An optical fiber cable 100 includes at least one optical fiber core 140 and a sheath containing the optical fiber core. The optical fiber core 140 includes optical fibers 130. A total length of the optical fiber core 140 is longer than that of the sheath 160. The optical fiber core 140 is contained in the sheath 160 so that bending occurs in the optical fibers 130.

An optical fiber cable 100 includes at least one optical fiber core 140 and a sheath containing the optical fiber core. The optical fiber core 140 includes optical fibers 130. A total length of the optical fiber core 140 is longer than that of the sheath 160. The optical fiber core 140 is contained in the sheath 160 so that bending occurs in the optical fibers 130.

Methods and apparatus to control the acoustic properties of optical cables used as in-well oil and gas probes for acoustic monitoring, such as distributed acoustic sensing (DAS). One example aspect provides a solid path for the acoustic wave to propagate from an outside armor layer of the cable to the sensing optical waveguide embedded therein. Another example aspect offers ways to spatially dispose the optical sensing elements to create response delays indicative of the propagation speed and/or direction of an acoustic wave. Yet another example aspect provides ways to utilize additional spectral interrogation to increase ultimate spatial resolution. Yet another example aspect provides ways to locally vary the acoustic properties along the length of the cable.

Methods and apparatus to control the acoustic properties of optical cables used as in-well oil and gas probes for acoustic monitoring, such as distributed acoustic sensing (DAS). One example aspect provides a solid path for the acoustic wave to propagate from an outside armor layer of the cable to the sensing optical waveguide embedded therein. Another example aspect offers ways to spatially dispose the optical sensing elements to create response delays indicative of the propagation speed and/or direction of an acoustic wave. Yet another example aspect provides ways to utilize additional spectral interrogation to increase ultimate spatial resolution. Yet another example aspect provides ways to locally vary the acoustic properties along the length of the cable.

A cable includes a guide element and a signal line. The guide element extends flatly on a guide plane, and the signal line is guided along a winding path on the guide plane by the guide element. The signal line has multiple bends on the guide plane. In particular, the cable is suitable for use under high stretching loads by virtue of the winding course of the signal line. The cable is simultaneously particularly space-saving in that the line is guided solely within the guide plane. A method for producing the cable is also provided.

It is disclosed a cable for an overhead power transmission line, the cable comprising: a first optical unit comprising a first metal tube housing at least one an optical fiber suitable for sensing strain, the at least one optical fiber in the first metal tube being a tight buffered optical fiber fixed to an inner surface of the first metal tube; a second optical unit comprising a second metal tube comprising one or more loose optical fibers suitable for sensing temperature; and an armor comprising one or more layers of metal wires. The first optical unit is surrounded by at least one layer of semi-conductive or conductive material electrically contacting the outer surface of the first metal tube.

A cable includes a guide element and a signal line. The guide element extends flatly on a guide plane, and the signal line is guided along a winding path on the guide plane by the guide element. The signal line has multiple bends on the guide plane. In particular, the cable is suitable for use under high stretching loads by virtue of the winding course of the signal line. The cable is simultaneously particularly space-saving in that the line is guided solely within the guide plane. A method for producing the cable is also provided.