Abstract: A distributed acoustic sensing cable package having a polymer composite extruded over an optical waveguide to encase the waveguide and to form a crystalline matrix layer acoustically coupled to the waveguide. The crystalline matrix includes reinforcement fibers to further enhance transmission of a cable strain to the optical waveguide. During manufacture of the cable, the polymer composite may be extruded over the optical waveguide and subsequently subjected to heat treatment to increase the crystallinity of the polymer composite and increase the elastic modulus. Both axial and radial strain fields are effectively interact with cased fiber waveguide for producing measurable phase shift signal for distributed acoustic noise detection.

Abstract: A distributed acoustic sensing cable package having a polymer composite extruded over an optical waveguide to encase the waveguide and to form a crystalline matrix layer acoustically coupled to the waveguide. The crystalline matrix includes reinforcement fibers to further enhance transmission of a cable strain to the optical waveguide. During manufacture of the cable, the polymer composite may be extruded over the optical waveguide and subsequently subjected to heat treatment to increase the crystallinity of the polymer composite and increase the elastic modulus. Both axial and radial strain fields are effectively interact with cased fiber waveguide for producing measurable phase shift signal for distributed acoustic noise detection.

Abstract: A distributed acoustic sensing cable package having a polymer composite extruded over an optical waveguide to encase the waveguide and to form a crystalline matrix layer acoustically coupled to the waveguide. The crystalline matrix includes reinforcement fibers to further enhance transmission of a cable strain to the optical waveguide. During manufacture of the cable, the polymer composite may be extruded over the optical waveguide and subsequently subjected to heat treatment to increase the crystallinity of the polymer composite and increase the elastic modulus. Both axial and radial strain fields are effectively interact with cased fiber waveguide for producing measurable phase shift signal for distributed acoustic noise detection.

Abstract: A method of monitoring a substance in a well can include disposing at least one optical electromagnetic sensor and at least one electromagnetic transmitter in the well, and inducing strain in the sensor, the strain being indicative of an electromagnetic parameter of the substance in an annulus between a casing and a wellbore of the well. A system for monitoring a substance in a well can include at least one electromagnetic transmitter, and at least one optical electromagnetic sensor with an optical waveguide extending along a wellbore to a remote location, the sensor being positioned external to a casing in the wellbore.

Abstract: A system includes a light source, optical fiber coupled to the light source, one or more interferometers coupled to the optical fiber, wherein each interferometer of the one or more interferometers comprising a gauge length, a photodetector assembly coupled to the optical fiber, and an information handling system. The photodetector assembly is configured to detect backscattered light from the optical fiber and generate signals based on the detected backscattered light. The an information handling system is configured to receive the signals from the photodetector assembly, apply a de-convolution operation to the signals based on the gauge lengths of the one or more interferometers, and store the de-convolved signals.

Abstract: An illustrative distributed sensing system includes a fiberoptic cable, a transmitter module, and a receiver module. The transmitter module is coupled to the fiberoptic cable to communicate light in each of multiple independent paths to each of multiple positions along the cable, The receiver module is coupled to the fiberoptic cable to receive backscattered light from said multiple positions along the cable via the multiple independent paths. The receiver module includes at least one receiver for each of said multiple independent paths to obtain simultaneous measurements for each of said multiple positions. The multiple independent paths may be provided by wave division multiplexing, frequency division multiplexing, spatial mode division multiplexing, multicore fiber, and/or multiple fibers.

Abstract: Systems and methods for correcting chromatic dispersion in a remote distributed sensing application are disclosed. A remote distributed sensing system includes an interrogation subsystem configured to transmit an optical pulse and receive a reflection from the optical pulse. The remote distributed sensing system also includes a transit optical fiber coupled to the interrogation subsystem and having chromatic dispersion of a first slope at a frequency of the optical pulse, and an optical fiber under test being located in a remote location apart from the interrogation subsystem. The remote distributed sensing system additionally includes a chromatic dispersion compensator coupled in-line with at least one of the transit optical fiber and the optical fiber under test to adjust chromatic dispersion on the optical pulse in a direction of a second slope having an opposite sign from the first slope.

Abstract: An illustrative interferometric system with high-fidelity optical phase demodulation includes a receiver having a fiberoptic coupler that produces optical interferometry signals having mutual phase separations of 120° and balanced photo-detectors that each produce an electrical difference signal based on a respective pair of said optical interferometry signals. The system further includes circuitry that converts the electrical difference signals into measurements of an interferometric phase.

Abstract: An illustrative distributed acoustic sensing system includes a multi-mode optical fiber cable for distributed sensing and a distributed acoustic sensing interrogator coupled to the multi-mode optical fiber cable via a single mode optical fiber. The interrogator derives distributed acoustic measurements from Rayleigh backscattering light that is initiated with a substantially under-filled launch configuration that is designed to excite only the lowest-order modes of the multi-mode optical fiber. Mode conversion within the multi-mode optical fiber is anticipated to be negligible. For elastic scattering (i.e., Rayleigh scattering), it is further anticipated that the scattered light will be primarily returned in the incident propagation mode, thereby escaping the extraordinarily large coupling loss that would otherwise be expected from coupling a single-mode optical fiber to a multi-mode optical fiber for distributed sensing. Experiments with graded index multi-mode optical fiber have yielded positive results.

Abstract: An illustrative distributed acoustic sensing system includes a multi-mode optical fiber cable for distributed sensing and a distributed acoustic sensing interrogator coupled to the multi-mode optical fiber cable via a single mode optical fiber. The interrogator derives distributed acoustic measurements from Rayleigh backscattering light that is initiated with a substantially under-filled launch configuration that is designed to excite only the lowest-order modes of the multi-mode optical fiber. Mode conversion within the multi-mode optical fiber is anticipated to be negligible. For elastic scattering (i.e., Rayleigh scattering), it is further anticipated that the scattered light will be primarily returned in the incident propagation mode, thereby escaping the extraordinarily large coupling loss that would otherwise be expected from coupling a single-mode optical fiber to a multi-mode optical fiber for distributed sensing. Experiments with graded index multi-mode optical fiber have yielded positive results.

Abstract: A system includes a light source, optical fiber coupled to the light source, one or more interferometers coupled to the optical fiber, wherein each interferometer of the one or more interferometers comprising a gauge length, a photodetector assembly coupled to the optical fiber, and an information handling system. The photodetector assembly is configured to detect backscattered light from the optical fiber and generate signals based on the detected backscattered light. The an information handling system is configured to receive the signals from the photodetector assembly, apply a de-convolution operation to the signals based on the gauge lengths of the one or more interferometers, and store the de-convolved signals.

Abstract: A method of optical communication in a well can include launching light having substantially coherent phase into an optical waveguide extending in a wellbore, modulating light having substantially coherent phase in the wellbore, and receiving the modulated light transmitted via the same optical waveguide. A well system can include at least one optical waveguide extending in a wellbore, and a downhole optical modulator which modulates light transmitted via the optical waveguide, the optical modulator comprising a potassium titanyl phosphate crystal. Another method of optical communication in a well can include launching light into an optical waveguide extending in a wellbore, the light launched into the optical waveguide having information modulated thereon using a carrier, modulating light in the wellbore, the modulating comprising modulating information using a subcarrier of the carrier, and transmitting the light modulated in the wellbore via the same optical waveguide.

Abstract: A fiber optic sensor interrogation system with inbuilt passive power limiting capability based on stimulated Brillouin scattering that provides improved safety performance for use in explosive atmospheres.

Abstract: A fiber optic sensor interrogation system with inbuilt passive power limiting capability that provides improved safety performance for use in explosive atmospheres.

Abstract: A method of correlating physical locations with respective positions along an optical waveguide can include transmitting to the waveguide a signal including an indication of the transmitting location, and the waveguide receiving the signal. A system for correlating a physical location with a position along an optical waveguide can include a transmitter which transmits to the optical waveguide a signal including an indication of the transmitter location, and a computer which correlates the location to the position, based on the signal as received by the waveguide. A method of determining a position along an optical waveguide at which a signal is transmitted can include modulating on the signal an indication of a transmission location, and transmitting the signal to the waveguide, thereby causing vibration of the waveguide.

Abstract: An illustrative distributed sensing system includes a fiberoptic cable, a transmitter module, and a receiver module. The transmitter module is coupled to the fiberoptic cable to communicate light in each of multiple independent paths to each of multiple positions along the cable, The receiver module is coupled to the fiberoptic cable to receive backscattered light from said multiple positions along the cable via the multiple independent paths. The receiver module includes at least one receiver for each of said multiple independent paths to obtain simultaneous measurements for each of said multiple positions. The multiple independent paths may be provided by wave division multiplexing, frequency division multiplexing, spatial mode division multiplexing, multicore fiber, and/or multiple fibers.

Abstract: An illustrative distributed acoustic sensing system includes a multi-mode optical fiber cable for distributed sensing and a distributed acoustic sensing interrogator coupled to the multi-mode optical fiber cable via a single mode optical fiber. The interrogator derives distributed acoustic measurements from Rayleigh backscattering light that is initiated with a substantially under-filled launch configuration that is designed to excite only the lowest-order modes of the multi-mode optical fiber. Mode conversion within the multi-mode optical fiber is anticipated to be negligible. For elastic scattering (i.e., Rayleigh scattering), it is further anticipated that the scattered light will be primarily returned in the incident propagation mode, thereby escaping the extraordinarily large coupling loss that would otherwise be expected from coupling a single-mode optical fiber to a multi-mode optical fiber for distributed sensing. Experiments with graded index multi-mode optical fiber have yielded positive results.

Abstract: A method of correlating physical locations with respective positions along an optical waveguide can include transmitting to the waveguide a signal including an indication of the transmitting location, and the waveguide receiving the signal. A system for correlating a physical location with a position along an optical waveguide can include a transmitter which transmits to the optical waveguide a signal including an indication of the transmitter location, and a computer which correlates the location to the position, based on the signal as received by the waveguide. A method of determining a position along an optical waveguide at which a signal is transmitted can include modulating on the signal an indication of a transmission location, and transmitting the signal to the waveguide, thereby causing vibration of the waveguide.

Abstract: A system and method for providing greatly improved linear heat detection using fiber optic distributed temperature systems (DTS). The invention makes use of correction algorithms based on proportional-integral-derivative notions that anticipate exterior temperature increases based on the rate of measured temperature changes.

Abstract: A method of improving sampling resolution in a distributed temperature measurement system using a fiber optic distributed sensor by means of programmed delayed trigger signals to a laser light source in order to improve the spatial resolution of such systems.