Abstract: Systems and methods are provided for applying a protective graphene barrier to waveguides and using the protected waveguides in wellbore applications. A well monitoring system may comprise a waveguide comprising a graphene barrier, wherein the graphene barrier comprises at least one material selected from the group consisting of graphene, graphene oxide, and any combination thereof; a signal generator capable of generating a signal that travels through the waveguide; and a signal detector capable of detecting a signal that travels through the waveguide.

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: A disclosed downhole telemetry system employs an array of near-field electromagnetic communication devices to relay information along a tubular in a borehole. In some embodiments, the devices are permanently attached to pipe joints without requiring any structural modification of the pipe joints. As the pipe joints are strung together in the normal fashion to form a tubular, the devices automatically establish a wireless communications path between an uphole terminus device and any downhole sensors or tools. The devices can include built-in sensors to provide distributed sensing of parameters such as temperature and pressure. In some embodiments the device array incorporates redundancy to minimize the chance of a communications network failure. The device array has applications for logging-while-drilling, production testing, well completion, reservoir monitoring, and well control.

Abstract: A gravitational logging method includes optically obtaining gravitational field measurements from one or more downhole or subsea sensor units. The method also includes inverting the gravitational field measurements as a function of position to determine a formation property. A related system includes one or more downhole or subsea sensor units to optically obtain gravitational field measurements. The system also includes a processing unit that inverts the gravitational field measurements as a function of position to determine a formation property.

Abstract: A gravitational logging method includes obtaining gravitational field measurements from a permanent array of downhole or subsea sensor units. The method also includes inverting the gravitational field measurements as a function of position to determine a reservoir property. A related system includes a permanent array of downhole or subsea sensor units to obtain gravitational field measurements. The system also includes a processing unit that inverts the gravitational field measurements as a function of position to determine a reservoir property.

Abstract: A system includes a light source and a nonlinear converter optically coupled to and remote from the light source. The nonlinear light converter converts a light pulse received from the light source to a broadened or spectrum-shifted light pulse. The system also includes a sensor in situ with the nonlinear light converter. The sensor performs a sense operation based on the broadened or spectrum-shifted light pulse and generates an electrical signal corresponding to the sense operation. The system also includes an electro-optical interface in situ with the sensor that transforms the electrical signal to an optical signal for conveyance to a signal collection interface.

Abstract: Permanent electromagnetic (EM) monitoring of the regions around and between wells may employ a casing string positioned within a borehole through the subsurface formations of interest. At least two passivated electrodes are mounted on the casing string to sense electric fields in the formation. Though only capacitively coupled to the formation, the passivated electrodes nevertheless provide a potential difference to an electro-optical transducer, which in turn modifies a property of the light passing along an optical fiber attached to the casing string. An interface unit senses the modified property to derive a measure of the electric field between each pair of passivated electrodes. The passivated electrodes have a contact surface that is conductive but for one or more layers of non-reactive (and thus electrically insulating) materials. Illustrative materials include metal oxides, polymers and ceramics, but the layers are preferably kept very thin to maximize the coupling capacitance with the formation.

Abstract: A well tool can include an outer housing and a vibratory transmitter disposed in the outer housing. The vibratory transmitter transmits a vibratory signal to an optical line disposed in the outer housing. A well system can include an optical line extending in a wellbore, and at least one well tool secured to the optical line and including a vibratory transmitter which transmits a vibratory signal to the optical line. The optical line conveys the well tool into the wellbore. A method of telemetering data from a well tool to an optical line can include securing the well tool to the optical line without optically connecting the well tool to the optical line, and conveying the well tool in a wellbore on the optical line.

Abstract: A disclosed system for downhole time domain reflectometry (TDR) includes a surface electro-optical interface, a downhole electro-optical interface, a fiber-optic cable that couples the surface electro-optical interface and the downhole electro-optical interface, and an electrical transmission line that extends from the downhole electro-optical interface into a wellbore environment to enable TDR operations. A described method for downhole TDR includes transmitting an optical signal to a downhole environment, converting the optical signal to an electrical signal in the downhole environment, reflecting the electrical signal using an electrical transmission line in the downhole environment, analyzing data corresponding to the reflected electrical signal, and displaying a result of the analysis.

Abstract: An illustrative downhole sensing system and method employs an array of downhole sensors such as extrinsic Fabry-Perot interferometers, each of which provides a sequence of light pulses having spectra indicative of a measurand for that downhole sensor. An optical fiber conveys the sequences in a time-multiplexed fashion to a receiver having at least one gating element that passes only a selected one of the sequences and at least one spectrometer that receives the selected one of said sequences and responsively measures a light spectrum. Notably, the integration interval for the spectrometer measurement is substantially greater than the pulse period of each sequence, including multiple pulses within the measurement by the spectrometer.

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 method of flowing fluid from a formation, the method comprising: sensing presence of a reservoir impairing substance in the fluid flowed from the formation; and automatically controlling operation of at least one flow control device in response to the sensing of the presence of the substance. A well system, comprising: at least one sensor which senses whether a reservoir impairing substance is present; and at least one flow control device which regulates flow of a fluid from a formation in response to indications provided by the sensor.

Abstract: A downhole optical sensor system includes at least one optical sensor positioned in a borehole and coupled to an interface via a fiber optic cable. Each of the optical sensors includes a waveguide for conducting light, and a reagent region positioned between the waveguide and a fluid in the borehole to absorb a portion of the light from the waveguide, the portion being dependent upon a concentration of a chemical species in the fluid. A method for operating a well includes deploying one or more downhole optical sensors in a fluid flow path in the well, probing the one or more downhole optical sensors from a surface interface to detect concentrations of one or more chemical species, and deriving a rate of scale buildup or corrosion based at least in part on the detected concentrations.

Abstract: Sensors, systems and methods for downhole electromagnetic field detection, including a downhole micro-opto-electro-mechanical system (MOEMS) electromagnetic field sensor that includes a first surface that is at least partially reflective, a second surface that is at least partially reflective and suspended by one or more flexible members to define an optical cavity having a variable distance between the first and second surfaces, and a first conductive layer attached to the second surface and having a first electric charge. An electric field passing through the optical cavity interacts with the first electric charge and displaces the second surface to alter the variable distance and cause a spectrum variation in light exiting the sensor.

Abstract: Sensors, systems and methods for downhole electromagnetic field detection, including a downhole micro-opto-electro-mechanical system (MOEMS) electromagnetic field sensor that includes a first surface that is at least partially reflective, a second surface that is at least partially reflective and suspended by one or more flexible members to define an optical cavity having a variable distance between the first and second surfaces, and a magnetically polarized layer attached to the second surface. A magnetic field passing through the optical cavity interacts with the magnetically polarized layer and a gradient in the magnetic field produces a displacement of the second surface that alters the variable distance and causes a spectrum variation in light exiting the sensor.

Abstract: A disclosed system includes a plurality of ion selective fiber sensors configured to measure treatment concentration variance, and a computer in communication with the plurality of ion selective fiber sensors. The computer determines treatment coverage for different downhole zones using information received from the plurality of ion selective fiber sensors. A disclosed method includes collecting data from a plurality of ion selective fiber sensors configured to measure treatment concentration variance. The method also includes determining treatment coverage for different downhole zones using information received from the plurality of ion selective fiber sensors. A disclosed downhole treatment management system includes a data analysis unit that collects data from a plurality of downhole ion selective fiber sensors configured to measure treatment concentration variance, and that determines treatment coverage for different downhole zones using the collected data.

Abstract: Sensors, systems and methods for downhole electromagnetic field measurement, including a downhole micro-opto-electro-mechanical system (MOEMS) electromagnetic field sensor that includes a first surface that is at least partially reflective, a second surface that is at least partially reflective and suspended by one or more flexible members to define an optical cavity having a variable distance between the first and second surfaces, a first conductive layer attached to the first surface, and a second conductive layer attached to the second surface. The first and second conductive layers have an electrical potential proportional to an electromagnetic field within a formation surrounding the sensor. The electrical potential produces an electric field that displaces the second surface to alter the variable distance and cause a spectrum variation in light exiting the sensor.

Abstract: Fiber optic enabled casing collar locator systems and methods include a wireline sonde or a coil tubing sonde apparatus configured to be conveyed through a casing string by a fiber optic cable. The sonde includes at least one permanent magnet producing a magnetic field that changes in response to passing a collar in the casing string, a coil that receives at least a portion of the magnetic field and provides an electrical signal in response to the changes in the magnetic field, and a light source that responds to the electrical signal to communicate light along an optical fiber to indicate passing collars.

Abstract: Fiber optic enabled casing collar locator systems and methods including a wireline sonde or a coil tubing sonde apparatus configured to be conveyed through a casing string by a fiber optic cable. The sonde includes at least one permanent magnet producing a magnetic field that changes in response to passing a collar in the casing string. Such magnetic field changes induce voltages changes within associated pick-up electrical coil conductors. Some embodiments include a cylinder configured to change its diameter in response to the changes in the magnetic field and/or impressed voltage, and an optical fiber wound around the cylinder to convert the cylinder diameter change into an optical path length change for light being communicated along the fiber optic cable. The cylinder may include a magnetostrictive material or a piezoelectric material.

Abstract: A formation monitoring system includes a casing. An array of electromagnetic field sensors is positioned in the annular space and configured to communicate with the surface via a fiberoptic cable. A computer coupled to the fiberoptic cable receives measurements from the array and responsively derives the location of any fluid fronts in the vicinity such as an approaching flood front to enable corrective action before breakthrough. A formation monitoring method includes: injecting a first fluid into a reservoir formation; producing a second fluid from the reservoir formation via a casing in a borehole; collecting electromagnetic field measurements with an array of fiberoptic sensors in an annular space, the array communicating measurements to a surface interface via one or more fiberoptic cables; and operating on the measurements to locate a front between the first and second fluids.