Abstract: Methods and systems for the use of partially reflective materials and coatings for optical communications in a wellbore environment are provided. In one embodiment, methods for remote communication in a wellbore comprise: positioning an optical fiber in the wellbore, wherein at least a portion of the optical fiber comprises a partially reflective coating; transmitting an output optical signal from an optical source through the optical fiber; and receiving a reflected optical signal from the optical fiber at an optical detector, wherein at least one optical property of the reflected optical signal is indicative of a downhole condition.

Abstract: Disclosed are methods and apparatus for using an audible signal to monitor conditions at a downhole location in a well through use of a well cable containing a fiber optic, which may be either a slickline or a wireline fiber-optic cable, and providing an audible signal which varies in response to the monitored condition. The condition monitored can be strain in the fiber optic well cable, which can be sensed in one or more locations in the fiber optic well cable, in many examples through use of a sensor such as a Bragg grating associated with or formed in an optical fiber within the well cable. In some examples, a temperature measurement may be used to compensate for temperature effects impacting the strain measurement.

Abstract: A method and system for operating a frequency comb. The method may comprise operating an electro-optic (EO) frequency comb with two phase-locked microwave signals to produce an optical output, detecting the optical output with an optical receiver as one or more beat notes, and detecting the one or more beat notes with a radio-frequency spectrum analyzer. The system may comprise an EO frequency comb and an EO phase modulator disposed in the bulk nonlinear crystal resonator. The EO frequency comb may further comprise a continuous-wave laser and a bulk nonlinear crystal resonator connected to the continuous-wave laser.

Abstract: The disclosed embodiments include downhole communication networks and methods to form downhole communication networks. In one embodiment, a downhole communication network includes a plurality of communication tags deployed in a wellbore. Each communication tag of the plurality of communication tags includes a sensor operable to detect wellbore and hydrocarbon resource properties proximate the respective communication tag. Each communication tag of the plurality of communication tags also includes a storage medium operable to store data indicative of the at least one of wellbore and hydrocarbon resource properties proximate the respective communication tag. Each communication tag of the plurality of communication tags further includes a transmitter operable to transmit a signal indicative of one or more of the wellbore and hydrocarbon resource properties.

Abstract: The disclosed embodiments include downhole telemetry systems and methods to obtain data indicative of wellbore properties. In one embodiment, a downhole telemetry system includes a plurality of sensor boxes, where each of the plurality of sensor boxes is deployed along a casing of a wellbore. Each sensor box is operable to obtain data indicative of at least one property of the wellbore and to transmit signals comprising data indicative of the at least one property of the wellbore. The downhole telemetry system also includes a downhole tool coupled to a conveyance and deployable in the wellbore. The downhole tool operable to transmit an activation signal to one or more sensor boxes of the plurality of sensor boxes to initiate communication with the one or more sensor boxes, and is also operable to receive signals comprising data indicative of the at least one property of the wellbore.

Abstract: The disclosed embodiments include methods and networks to determine a boundary of a cement mixture. In one embodiment, the method includes detecting first acoustic signals transmitted from at least one of a first plurality of acoustic tags that are mixed with cement slurry, where the cement slurry is deposited in a first section of a wellbore in an annulus between a casing and the first section of the wellbore. The method also includes determining a location of a first boundary of the cement slurry based on the first acoustic signals.

Abstract: A method and system for transmitting information in well operations. The method for transmitting information may comprise splitting a coherent light into a plurality of wavelengths with a demultiplexer within a fiber comb transmitter and encoding information onto at least one of the plurality of wavelengths within the fiber comb transmitted. The method may further comprise combining the plurality of wavelengths into a second coherent light with a wavelength division multiplexer within the fiber comb transmitter and broadcasting the second coherent light from the frequency comb transmitter. A downhole telemetry system may comprise a frequency comb transmitter, which may comprise a laser source and a modulator. The modulator may further comprise a demultiplexer, an encoder, and a wavelength division multiplexer. The frequency comb transmitter may also comprise a fiber optic cable and a frequency comb receiver.

Abstract: In some embodiments, a method and apparatus, as well as an article, may operate to determine downhole properties based on detected optical signals. An optical detection system can include a fiber optic cable having a sensing location to generate a reflected measurement signal representative of measurement parameters. The optical detection system can further include a light source to transmit a measurement signal to cause the sensing location to provide the reflected measurement signal. The optical detection system can further include an optical detector comprising a single-photon detector (SPD) for detecting the reflected measurement signal received over the fiber optic cable. The optical detection system can further include a housing for enclosing the optical detector and to optically shield the optical detector, the housing including an aperture for passage of the fiber optic cable. Additional apparatuses, systems, and methods are disclosed.

Abstract: Systems, methods, and computer-readable media for providing adaptive feedback in downhole telemetry in a wellbore. A feedback system includes a source assembly, which can be located on the surface or downhole, and a receiving assembly, which can likewise be located on the surface or downhole. The source assembly includes a source device that transmits a light signal having a first phase, and an encoder coupled to the source device. The receiving assembly comprising an oscillator that transmits an oscillator having a second phase, a coupler that couples the light signal with the oscillator signal, a detector and difference amplifier that detect and determine the difference between the first phase and second phase and a processor that receives the difference between the phases and provides the difference to an encoder so that the encoder can adjust the oscillator phase.

Abstract: The disclosed embodiments include methods and networks to determine a boundary of a cement mixture. In one embodiment, the method includes detecting first acoustic signals transmitted from at least one of a first plurality of acoustic tags that are mixed with cement slurry, where the cement slurry is deposited in a first section of a wellbore in an annulus between a casing and the first section of the wellbore. The method also includes determining a location of a first boundary of the cement slurry based on the first acoustic signals.

Abstract: A full-duplex borehole communication system includes a single light source to generate a light signal. A downlink modulator is coupled to the light source to modulate the light signal in response to downlink data using a first protocol to generate a first modulated light signal. An uplink modulator is coupled to the downhole modulator to modulate the first modulated light signal in response to uplink data using a second protocol to generate a second modulated light signal. A downlink receiver is coupled to the downlink modulator to demodulate the first modulated signal to recover the downlink data. An uplink receiver is coupled to the uplink modulator and configured to demodulate the second modulated light signal to recover the downlink data and the uplink data. Asymmetric protocols are used between the downhole portion of the system and the uphole portion.

Abstract: A subterranean formation can be monitored using motion data. For example, a series of time-lapsed images of a well site can be received by a processing device. Motion data can be extracted from the series of time-lapsed images. The motion data can correspond to a difference between images in the series of time-lapsed images. Changes to a surface of the well site can be determined based on the motion data. Features of a subterranean formation of the well site can be determined based on the changes to the surface.

Abstract: A telemetry system is operable to transmit data by bridging the low signal bandwidth available to high temperature electronics with the high spectral bandwidth available in optical fiber. A transmitter, such as a frequency comb, generates light to a fiber and the light is demultiplexed to separate the light into separate wavelengths. Modulators encode downhole data onto each wavelength and a multiplexer recombines the wavelengths onto a single fiber that passes the light back to the surface where a second demultiplexer separates the light to be transmitted to distinct receivers that detect the encoded data. A dual fiber system may also be utilized. One or more commands may also be transmitted to the downhole tools by transmitted the encoded command to a coupler that is coupled to a multiplexer where a downhole receiver determines the downhole tool that should receive the associated command.

Abstract: In some embodiments, a method and apparatus, as well as an article, may operate to determine properties based on detected optical signals. An optical detection apparatus can include an optical detector for detecting light received through a fiber optic cable; a housing for enclosing the optical detector; a light source; and a cooling mechanism having the housing mounted thereto. The cooling mechanism can maintain the temperature of a light-sensitive region of the optical detector within a temperature range below 210 degrees Kelvin. Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, a method and apparatus, as well as an article, may operate to determine downhole properties based on detected optical signals. An optical detection system can include a fiber optic cable having a sensing location to generate a backscattered Rayleigh signal representative of measurement parameters. The optical detection system can further include a light source to transmit a measurement signal to cause the sensing location to provide the backscattered Rayleigh signal. The optical detection system can further include an optical detector comprising a single-photon detector (SPD) for detecting the backscattered Rayleigh signal received over the fiber optic cable. The optical detection system can further include circuitry to produce an acoustic signal representative of a downhole property based on the phase of the backscattered Rayleigh signal. Additional apparatuses, systems, and methods are disclosed.

Abstract: The disclosed embodiments include an optical fiber having a graphene coating, a method to apply a graphene coating onto an optical fiber, and a fiber optic cable having a graphene coating. In one embodiment, the optical fiber includes an optical core that extends along a longitudinal axis. The optical fiber also includes a carbon based coating that covers the optical core along the longitudinal axis. The optical fiber also includes a layer of graphene formed on a first surface of the carbon based coating. The layer of graphene is formed from a laser induction process that includes focusing a laser beam at the carbon based coating to photothermally convert the first surface of the carbon based coating into graphene.

Abstract: A downhole tool apparatus is disclosed that includes an input fiber optic cable coupled to an electro-optic modulator. The input fiber optic cable propagates first and second actively orthogonally polarized light beams. The electro-optic modulator modulates the first and second actively orthogonally polarized light beams in response to a measurement data stream (e.g., telemetry data). A single light beam comprising the modulated first and second actively orthogonally polarized light beams is propagated over an output fiber optic cable so that the modulated first and the second actively orthogonally polarized light beams propagate the same data through the output fiber optic cable. Recovery circuitry coupled to the single light beam is then used to detect, demodulate, and decode the original measurement data stream.

Abstract: A system, in some embodiments, comprises: a light source; a fiber optic cable coupled to surface equipment and to downhole equipment and illuminated with fixed-wavelength light by said light source; and a modulator to modulate said fixed-wavelength light in the fiber optic cable to communicate data between the surface equipment and the downhole equipment, wherein the modulator uses a modified half-duplex telemetry scheme.

Abstract: A method and system for transmitting information in well operations. The method for transmitting information may comprise splitting a coherent light into a plurality of wavelengths with a demultiplexer within a fiber comb transmitter and encoding information onto at least one of the plurality of wavelengths within the fiber comb transmitted. The method may further comprise combining the plurality of wavelengths into a second coherent light with a wavelength division multiplexer within the fiber comb transmitter and broadcasting the second coherent light from the frequency comb transmitter. A downhole telemetry system may comprise a frequency comb transmitter, which may comprise a laser source and a modulator. The modulator may further comprise a demultiplexer, an encoder, and a wavelength division multiplexer. The frequency comb transmitter may also comprise a fiber optic cable and a frequency comb receiver.

Abstract: A downhole tool apparatus is disclosed that includes an input fiber optic cable coupled to an electro-optic modulator. The input fiber optic cable propagates first and second actively orthogonally polarized light beams. The electro-optic modulator modulates the first and second actively orthogonally polarized light beams in response to a measurement data stream (e.g., telemetry data). A single light beam comprising the modulated first and second actively orthogonally polarized light beams is propagated over an output fiber optic cable so that the modulated first and the second actively orthogonally polarized light beams propagate the same data through the output fiber optic cable. Recovery circuitry coupled to the single light beam is then used to detect, demodulate, and decode the original measurement data stream.