Abstract: Various optical fiber-based seismic monitoring system embodiments include a light source that drives an optical fiber positioned within a borehole. At least one light sensor analyzes Rayleigh backscattered light to obtain an acoustic signal for each of multiple points along the borehole. One or more processors operate to determine microseismic event direction, distance, and/or intensity based at least in part on phase information of said acoustic signals. The acoustic signal cross-correlations, semblances, or phase-sensitive similarity measures can be determined as a function of scanning direction to accurately determine the relevant microseismic event information. The optical fiber may be positioned in the cemented annulus of a cased borehole having a shape that extends along more than one dimension (e.g., an L-shaped borehole).

Abstract: A disclosed remote work system includes a light source and a nonlinear converter optically coupled to and remote from the light source. The nonlinear light converter converts a narrowband light pulse received from the light source to a converted spectrum light pulse. The system also includes a work element coupled to the nonlinear light converter. The work element performs a work operation using the converted spectrum light pulse. A related remote work method includes generating a narrowband light pulse and conveying the narrowband light pulse to a remote location. The method also includes converting the narrowband light pulse to a converted spectrum light pulse at the remote location. The method also includes performing a sense operation or work operation at the remote location using the converted spectrum light pulse.

Abstract: A communication system can include a transmitter which transmits a signal, and at least one sensing device which receives the signal, the sensing device including a line contained in an enclosure, and the signal being detected by the line through a material of the enclosure. A sensing system can include at least one sensor which senses a parameter, at least one sensing device which receives an indication of the parameter, the sensing device including a line contained in an enclosure, and a transmitter which transmits the indication of the parameter to the line through a material of the enclosure. Another sensing system can include an object which displaces in a subterranean well. At least one sensing device can receive a signal from the object. The sensing device can include a line contained in an enclosure, and the signal can be detected by the line through a material of the enclosure.

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 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: 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 acoustic telemetry system includes a downhole acoustic telemetry module that generates an acoustic uplink signal such as a pulsed fluid flow or compressional waves in a tubing string wall. An optical waveguide transports an optical signal representing the acoustic uplink signal to the surface interface. A related telemetry method includes acquiring measurements downhole, transmitting the measurements in the form of an acoustic signal, and sensing the acoustic signal via an optical waveguide.

Abstract: A disclosed subsurface electromagnetic field monitoring system includes at least one fiberoptic cable to optically communicate measurements from an array of electromagnetic field sensors in a borehole.

Abstract: A method of generating an acoustic signal in a subterranean well can include converting optical energy to acoustic energy downhole, thereby transmitting the acoustic signal through a downhole environment. A well system can include an optical acoustic transducer disposed in the well and coupled to an optical waveguide in the well, whereby the transducer converts optical energy transmitted via the optical waveguide to acoustic energy. An optical acoustic transducer for use in a subterranean well can include various means for converting optical energy transmitted via an optical waveguide to acoustic energy in the well.

Abstract: A method of logging a well can include conveying an optical waveguide and at least one signal generator with a conveyance into the well, causing the signal generator to generate at least one signal in the well, and receiving the signal as distributed along the optical waveguide. A well logging system can include a conveyance with an optical waveguide, and at least one signal generator which is conveyed by the conveyance into a well with the optical waveguide, whereby the signal generator generates at least one signal received with the optical waveguide.

Abstract: A well flow velocity measurement method can include transmitting an acoustic signal through at least one fluid composition in a well, detecting velocities of the acoustic signal in both opposite directions along an optical waveguide in the well, the optical waveguide being included in a distributed acoustic sensing system, and determining an acoustic velocity in the fluid composition based on the velocities of the acoustic signal. Another well flow velocity measurement method can include propagating at least one pressure pulse through at least one fluid composition in a well, detecting a velocity of the pressure pulse along an optical waveguide in the well, the optical waveguide being included in a distributed acoustic sensing system, and determining an acoustic velocity in the fluid composition based on the velocity of the pressure pulse.

Abstract: A disclosed subsurface electromagnetic field monitoring system employs at least one fiberoptic cable to optically communicate measurements from an array of electromagnetic field sensors in a borehole. A data processing system that receives the measurements and responsively models the subsurface electromagnetic field, which in at least some cases is generated by a controlled source such as a downhole electric or magnetic dipole source or a casing that serves as an electrode for injecting a distributed current into the formation.

Abstract: A disclosed formation monitoring system includes a casing that defines an annular space within a borehole. 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 said measurements and responsively derives the location of any fluid fronts in the vicinity such as a an approaching flood front to enable corrective action before breakthrough. A disclosed 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 between said casing and said borehole, said array communicating measurements to a surface interface via one or more fiberoptic cables; and operating on said measurements to locate a front between the first and second fluids.

Abstract: A disclosed remote work system includes a light source and a nonlinear converter optically coupled to and remote from the light source. The nonlinear light converter converts a narrowband light pulse received from the light source to a converted spectrum light pulse. The system also includes a work element coupled to the nonlinear light converter. The work element performs a work operation using the converted spectrum light pulse. A related remote work method includes generating a narrowband light pulse and conveying the narrowband light pulse to a remote location. The method also includes converting the narrowband light pulse to a converted spectrum light pulse at the remote location. The method also includes performing a sense operation or work operation at the remote location using the converted spectrum light pulse.

Abstract: A disclosed 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 A related method includes generating a light pulse and conveying the light pulse to a remote nonlinear light converter. The method also includes converting the light pulse to a broadened or spectrum-shifted light pulse.

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: 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: Detecting and correcting unintended fluid flow between subterranean zones. At least some of the illustrative embodiments are methods including: injecting a first fluid into a subterranean zone, the injecting by way of a first borehole; making a reading indicative of surface deformation; identifying, based on the reading indicative of surface deformation, a flow path for a second fluid out of the subterranean zone; placing a compound into the flow path, the compound reduces the flow of the second fluid through the flow path.

Abstract: A communication system can include a transmitter which transmits a signal, and at least one sensing device which receives the signal, the sensing device including a line contained in an enclosure, and the signal being detected by the line through a material of the enclosure. A sensing system can include at least one sensor which senses a parameter, at least one sensing device which receives an indication of the parameter, the sensing device including a line contained in an enclosure, and a transmitter which transmits the indication of the parameter to the line through a material of the enclosure. Another sensing system can include an object which displaces in a subterranean well. At least one sensing device can receive a signal from the object. The sensing device can include a line contained in an enclosure, and the signal can be detected by the line through a material of the enclosure.

Abstract: An apparatus and method for use in distributed temperature sensing (DTS) systems to reduce coherent Rayleigh scattering in fiber optic cables by using photonic crystal fibers.