Abstract: An example omnidirectional sensing system may include a fiber optic cable wrapped around a sphere or spheroid in no preferred direction. The wrapped fiber optic cable may make the system more receptive to acoustic disturbances and increase the fidelity of the sensor in the area of the sphere or spheroid. The system may be used, for instance, for vertical seismic profiling via a wireline technique, placement at the surface of the earth for surface seismic, and in marine applications.

Abstract: Multiplexed microvolt sensor systems and methods are described. An example system may include a pulsed light source, a first optical waveguide segment operatively coupled to the pulsed light source, an optical circulator including a first port, a second port, and a third port, the first port being operatively coupled to the first optical waveguide segment, a second optical waveguide segment operatively coupled to the second port of the optical circulator, and an array of sensor elements. Each of the sensor elements may include a detector and an electro-optical modulator, the electro-optical modulator being operatively coupled to the second optical waveguide segment.

Abstract: A method may include transmitting a narrowband signal into a formation using a transmitter located in a wellbore. The narrowband signal is modified by passage of through the formation and the formation reflects at least a portion of the narrowband signal back to the wellbore resulting in a modified narrowband signal having a first frequency. The method also includes sensing the modified narrowband signal with an optical waveguide positioned in the wellbore, transmitting a source signal along a length of the optical waveguide, and obtaining a backscattered return signal from the optical waveguide. The backscattered return signal is sampled at a second frequency that is less than the Nyquist rate of the modified narrowband signal. The method further includes processing the backscattered return signal to obtain an amplitude of the modified narrowband signal.

Abstract: A distributed optical fiber sensing system is provided. The system can include an interrogator, a transmission optical fiber, a sensing optical fiber, and a reflector. Each of the transmission optical fiber and the sensing optical fiber includes at least one circulator. The reflector is optically coupled to the transmission optical fiber for sensing separate regions along the sensing optical fiber.

Abstract: An optical link including an optical computing device having an integrated computational element (ICE), and a method for using the device to perform a remote measurement of a characteristic of a sample with the optical computing device are provided. The optical computing device provides an optical computing signal proportional to a characteristic of a sample from an interacted light provided to the ICE. The device includes an optical transducer to provide a modulating signal based on the optical computing signal and a modulator to modulate a first portion of a transmission light in an optical waveguide based on the modulating signal.

Abstract: An example method includes at least partially positioning within a wellbore an optical fiber of a distributed acoustic sensing (DAS) data collection system. Seismic data from the DAS data collection system may be received. The seismic data may include seismic traces associated with a plurality of depths in the wellbore. A quality factor may be determined for each seismic trace. One or more seismic traces may be removed from the seismic data based, at least in part, on the determined quality factors.

Abstract: An example system for detecting mud pulses may include a distributed acoustic sensing (DAS) data collection system coupled to a downhole drilling system, and an information handling system communicably coupled to the DAS data collection system. The information handling system may include a processor and memory coupled to the processor. The memory may contain a set of instructions that, when executed by the processor, cause the processor to receive quadrature DAS data signals from the DAS data collection system, determine a first template signal associated with mud pulses, transform the determined first template signal into analytic representation form, perform a matched filter operation using the quadrature DAS data signals and the transformed first template signal, and analyze an output signal of the matched filter operation to detect mud pulses in the downhole drilling system.

Abstract: A distributed acoustic sensing cable including an optical fiber waveguide configured to provide light signal transmission and an acoustic device coupled to the optical fiber waveguide and configured to provide acoustic signal transmission. The acoustic device includes a polymer composite having reinforced fibers embedded therein. The polymer composite having acoustic waveguides for attenuating undesirable acoustic waves propagating along the distributed acoustic sensing cable and optical fibers embedded within the polymer composite that extend along an axial length of the acoustic device that facilitate the light signal transmission.

Abstract: A system includes an optical fiber and an interrogator to provide source light to the optical fiber. The system also includes a receiver coupled to the optical fiber. The receiver includes at least one fiber optic coupler that receives backscattered light and that produces optical interferometry signals from the backscattered light. The receiver also includes photo-detectors that produce an electrical signal for each of said optical interferometry signals. The system also includes at least one digitizer that digitizes the electrical signals. The system also includes at least one processing unit that calculates I/Q data from the digitized electrical signals, corrects the I/Q data based on ellipse fitting, determines phase values based on the corrected I/Q data, and determines distributed sensing parameter values based on the phase values.

Abstract: An example system for detecting mud pulses may include a distributed acoustic sensing (DAS) data collection system coupled to a downhole drilling system, and an information handling system communicably coupled to the DAS data collection system. The information handling system may include a processor and memory coupled to the processor. The memory may contain a set of instructions that, when executed by the processor, cause the processor to receive quadrature DAS data signals from the DAS data collection system, determine a first template signal associated with mud pulses, transform the determined first template signal into analytic representation form, perform a matched filter operation using the quadrature DAS data signals and the transformed first template signal, and analyze an output signal of the matched filter operation to detect mud pulses in the downhole drilling system.

Abstract: Multiplexed microvolt sensor systems and methods are described. An example system may include a pulsed light source, a first optical waveguide segment operatively coupled to the pulsed light source, an optical circulator including a first port, a second port, and a third port, the first port being operatively coupled to the first optical waveguide segment, a second optical waveguide segment operatively coupled to the second port of the optical circulator, and an array of sensor elements. Each of the sensor elements may include a detector and an electro-optical modulator, the electro-optical modulator being operatively coupled to the second optical waveguide segment.

Abstract: A system includes an optical fiber and an interrogator to provide source light to the optical fiber. The system also includes a receiver coupled to the optical fiber. The receiver includes at least one fiber optic coupler that receives backscattered light and that produces one or more optical interferometry signals from the backscattered light. The receiver also includes photo-detectors that produce an electrical signal for each of the one or more optical interferometry signals. The system also includes at least one digitizer that digitizes each electrical signal. The system also includes at least one processing unit that processes each digitized electrical signal to obtain a distributed sensing signal and related energy spectrum information.

Abstract: Mitigating back reflection in fiber optic cables when coupling two fiber optic cables, for example, for implementing in harsh environments including wellbores. As described below, light from a source can travel toward a target through a first fiber optic cable and a second fiber optic cable coupled to the first fiber optic cable using a coupling system. The two fiber optic cables can be coupled such that all or a portion of back reflection at the coupling part is absorbed rather than permitted to travel back toward the source through the first fiber optic cable.

Abstract: Various embodiments include apparatus and methods to measure a parameter of interest using a fiber optic cable. The parameters can be provided by a process that provides for multiplexed or distributed measurements. A multiplexed or a distributed architecture can include acoustic sensor units placed selectively along an optical fiber such that the acoustic sensor units effectively modulate the optical fiber with information regarding a parameter to provide the information to an interrogator coupled to the optical fiber that is separate from the acoustic sensor units.

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 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 distributed optical fiber sensing system is provided. The system can include an interrogator, a transmission optical fiber, a sensing optical fiber, and a reflector. Each of the transmission optical fiber and the sensing optical fiber includes at least one circulator. The reflector is optically coupled to the transmission optical fiber for sensing separate regions along the sensing optical fiber.

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 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: Monitoring a well flow device by fiber optic sensing. A system includes processing circuitry configured to be disposed downhole in a wellbore. The processing circuitry is configured to receive a downhole parameter signal that represents an operational parameter of a well flow device in the wellbore, and perturb a fiber optic cable, based on the downhole parameter signal, to transmit the downhole parameter signal over the fiber optic cable. A fiber optic sensing system is coupled to the processing circuitry via the fiber optic cable. The fiber optic sensing system is configured to be disposed outside of the wellbore to extract, from the fiber optic cable, the downhole parameter signal.