Abstract: Methods and systems for characterizing fractures in a subterranean formation are provided. The method includes introducing an encapsulated explosive unit into a casing located in a wellbore within the subterranean formation and maintaining the encapsulated explosive unit in a stage of the casing. The method also includes detonating the encapsulated explosive unit within the stage to generate a pressure wave that passes through a group of perforations and into the fractures and measuring a reflected pressure wave using a pressure sensor coupled to the bridge plug to produce a pressure measurement. The method further includes converting the pressure measurement into an acoustic signal correlated with the pressure measurement by an acoustic signal generator contained in the bridge plug and transmitting the acoustic signal to apply acoustic pressure on a fiber optic cable coupled to an exterior surface of the casing.

Abstract: A cable protector can include a first side bar welded along a length of a casing section. A second side bar can be welded along the length of the casing section. The second side bar can be positioned substantially parallel to the first side bar. A cable can be positioned between the first side bar and the second side bar. The cable can be positioned while the casing section is being run-in-hole. A cover strip can be welded on top of first side bar and the second side bar. The cover strip can be welded in place while the casing section is being run-in-hole.

Abstract: A modular sensor system using electro acoustic technology to measure downhole properties, such as flow rate, density and fluid fraction of oil in a production string, is described. Modular sensor assemblies inside a wellbore collect various local fluid parameters at each location. The local fluid parameters are combined to determine the downhole properties.

Abstract: A method for using the depth derivative of distributed temperature sensing data to identify fluid levels, gas production intervals, water production intervals, and other fluid flow activities inside or near the well-bore during the production process. The method may include providing a fiber optic based distributed temperature sensing measurement system through a production region. Temperatures through the production region are gathered as a function of the depth in the subsurface well and as a function of the elapsed time. The gathered data is utilized to calculate the depth derivative of the temperature changes as a function of depth in the subsurface well and of the elapsed time. The depth derivative data for analysis of the fluid levels are displayed by operators to identify fluid levels, gas production intervals, water production intervals, and other fluid flow activities inside or near the wellbore during the production process.

Abstract: Fluid allocation in a well can be determined with a distributed temperature sensing system using data from a distributed acoustic sensing system. Flow data indicating a flow rate of a fluid through a perforation in a well based on an acoustic signal generated during a hydraulic fracturing operation in the well can be received. Warm-back data indicating an increase in temperature at the perforation can be received. A fluid allocation model can be generated based on the flow data and the warm-back data. The fluid allocation model can represent positions of the fluid in fractures formed in a subterranean formation of the well.

Abstract: Example systems and methods are described for performing multilateral well sensing in a downhole environment. In an example system, a cased parent wellbore and a cased lateral wellbore intersect at a lateral junction. A sensor is deployed within the cased lateral wellbore that communicably couples to a transmitter module, wherein the transmitter module is deployed within the cased lateral wellbore downhole of the lateral junction and configured to generate acoustic signals. An optical fiber cable is deployed within the cased parent wellbore and configured to receive acoustic signals transmitted by the transmitter module in the cased lateral wellbore.

Abstract: A well tool for sensing seismic activity at a downhole location has an anchoring mechanism for mechanically coupling the tool to a formation by contact engagement with a wall of a subterranean cavity in which the well tool is located. The anchoring mechanism is deployable by a pressure-triggered hydraulic actuator incorporated in the tool. The actuator is configured for pressure-triggered activation and for hydraulic actuation by agency of borehole fluids (e.g., drilling mud). The actuator can provide a persistent contacting force urging the anchoring mechanism into contact with the cavity wall, to promote firm coupling with the formation for seismic sensoring purposes.

Abstract: A single-use pressure-controlled actuator for downhole well tools or mechanisms is provided. The actuator is configured for control of activation/deactivation by agency of wellbore fluid pressure (e.g., pressure levels of drilling fluid or drilling mud in the wellbore). The actuator is further configured for hydraulic actuation by agency of the wellbore fluid. The actuator comprises a plunger displaceably mounted on a sealed cylinder body, with a non-reclosable frangible device closing off wellbore fluid access to an interior of the cylinder body. The frangible device is configured for automatic in response to exposure of wellbore fluid pressures exceeding a predetermined activation threshold. Failure of the frangible device causes exposure of the plunger to the wellbore fluid, resulting in actuated movement of the plunger by hydraulic action of the wellbore fluid.

Abstract: A system and method for enabling inductive charging through downhole casings for electro acoustic technology devices.

Abstract: Screen-outs can be detected from acoustical signals in a wellbore. Data based on an acoustic signal generated during a hydraulic fracturing operation in a wellbore formed through a subterranean formation can be received. An expected total flow rate of fluid being injected into the wellbore can be determined based on the data. An actual total flow rate of the fluid being injected into the wellbore can be determined. A screen-out that occurred can be identified by comparing the expected total flow rate and the actual total flow rate.

Abstract: The disclosed embodiments include distributed acoustic sensing (DAS) systems, methods to improve DAS properties of optical fibers, and optical fibers having improved DAS properties. In one embodiment, the system includes an optoelectronic device operable to generate optical pulses. The system also includes an optical fiber having a first end and a second end. The optical fiber is formed from a material having a Rayleigh back-scattering coefficient, and is operable to transmit optical pulses from the first end towards the second end and to reflect a first portion of the optical pulses towards the first end. The system further includes perturbations that are selectively imprinted on the optical fiber, where the perturbations are compatible with a range of wavelengths and are operable to reflect a second portion of the optical pulses towards the first end of the optical fiber if a wavelength of the optical pulses is within said range.

Abstract: Various embodiments include methods and apparatus structured to increase efficiencies of a drilling operation. These efficiencies may be realized with a fiber cable located in a wellbore at a well site, where the fiber cable can include an optical fiber disposed as a single handed helix in the fiber cable, where the optical fiber is disposed in the cable without having helix hand reversal. Construction of such fiber cables may include applying a twist to the optical fiber during insertion of the optical fiber into the fiber cable in a tubing process in which control of an amount of the twist to form a portion of the optical fiber can control excess fiber length in the tube. Additional apparatus, systems, and methods can be implemented in a variety of applications.

Abstract: A method is described for compensating measurement errors of fiber Bragg grating (FBG) sensors installed in fiber cables in down-hole oil and gas environments due to hydrogen darkening. The method involves loading a fiber of known length and multiple FBG sensors in a hydrogen chamber with control of temperature, hydrogen concentration, pressure, and time and adjusting each of the variables through a test matrix while continuously measuring and recording the fiber transmission loss and FBG spectrum changes, then creating a correlation map of fiber transmission loss vs. Bragg wavelength shift, and using that map for compensating the wavelength shift of downhole installed fiber cables as a function of their hydrogen induced transmission loss through time.

Abstract: A flow rate sensing system can include an optical waveguide, an optical interrogator that detects optical scatter in the optical waveguide, and an emitter that produces vibration in response to flow, the optical scatter being influenced by the vibration. A method of measuring flow rate can include detecting optical scattering in an optical waveguide, the optical scattering varying in response to changes in vibration produced by an emitter, and the vibration changing in response to the flow rate changing. A well system can include at least one tubular string positioned in a wellbore, multiple locations at which fluid flows between an interior and an exterior of the tubular string, multiple emitters, each of which produces vibration in response to the flow between the interior and the exterior of the tubular string, and an optical waveguide in which optical scatter varies in response to changes in the vibration.

Abstract: An electro acoustic technology (EAT) based micro seismic sensor and tiltmeter system and method is described for the measurement of minute deformations in downhole formations caused by hydraulic fracturing or other sources of pore pressure changes. A number of sensor arrays are described that are installed in clamp-on EAT devices installed in tool wells located in close proximity to hydraulically fractured wells.

Abstract: An opto-acoustic flowmeter can include an optical waveguide and an emitter that emits acoustic energy in response to flow, the acoustic energy comprising a flow rate dependent parameter. A flow rate measuring method can include configuring an emitter so that flow into or out of a tubular string causes the emitter to emit acoustic energy, arranging an optical line so that the acoustic energy is received by an optical waveguide of the optical line, and detecting optical scatter in the optical waveguide. A well system can include multiple locations where fluid is flowed between an earth formation and a tubular string in a wellbore, multiple emitters that produce an acoustic vibration corresponding to a flow rate of the fluid, an optical line that receives the vibrations, and an optical interrogator that detects optical scatter in an optical waveguide of the line, the scatter being indicative of the vibrations.

Abstract: A method and system for operating fiber optic monitoring systems utilizing solar panels, batteries, and an interrogator system with associated electronics for operating in cold climates.

Abstract: Disclosed is a fiber optic interrogation system unit with one or more controllable laser sources that are electrically tuned to fit the laser source requirements for different sensing principles. Such an interrogation unit would employ a designed optical configuration at the distal end of the optical fiber to enable DAS, DTS and stimulated Brillouin DSS to operate on the same optical fiber. It would provide a single fiber optic interrogation system with integrated DTS, DAS and DSS systems that is cost effective and simple in design.

Abstract: Systems and methods for distributed acoustic sensing based on coherent Rayleigh scattering are disclosed herein. A system comprises a pulse generator, an interferometer, a photo detector assembly, and an information handling system. The interferometer comprises a first and second optical switch each comprising a plurality of ports. The information handling system activates one port on each of the first and second optical switches so as to vary the optical path length of the interferometer. A method comprises splitting backscattered light from an optical pulse into a first portion and a second portion, activating one port of a first optical switch and one port of a second optical switch, sending the first portion into a first arm of an interferometer, sending the second portion into a second arm of the interferometer, combining the first and second portions to form an interferometric signal, and receiving the interferometric signal at a photodetector assembly.

Abstract: Methods are proposed for compensation of distortion in fiber Fabry-Perot interferometric (FFPI) sensors induced by dynamic wavelength dependent attenuation in subsurface wells. The methods involve measurement techniques that correct the reflective spectrum from one or more FFPI sensors utilizing a background low frequency spectrum for normalization.