Baker Hughes, a Ge Compnay, LLC

Baker Hughes Corporation

Baker Hughes Oilfield Operations LLC

Other

Baker Hughes Holdings LLC

William Albert Johnston

Ian Bradford Mitchell

Alexander Michael Barry

Ashwin Chandran

Paul Francis Wysocki

Daniel Boyd Cooper

Erik N Lee

Paul Wysocki

Dan Provenzano

Karl Kai Ku

Alexander M Barry

An optical system employs a method for measuring an acoustic signal in a wellbore. The optical system includes an optical interrogator and an optical fiber. The optical fiber has a plurality of nominal sites uniformly spaced apart along a longitudinal axis of the optical fiber. A plurality of gratings are formed in the optical fiber. Each of the plurality of gratings is associated with a nominal site and is separated from its associated nominal site by an offset distance. The offset distance is selected to reduce a destructive interference between reflections from the plurality of gratings. The optical interrogator transmits a light pulse into the optical fiber to measure the acoustic signal via a reflection of the light pulse from at least one of the plurality of gratings.

Grating position dithering for improved distributed acoustic sensing engineered fiber performance

An apparatus for sensing acoustic energy in a borehole penetrating the earth includes an optical interrogator and a sensing optical fiber having a length Ls optically coupled to the optical interrogator and configured to sense the acoustic energy to provide sensed acoustic data. The apparatus also includes a reference optical fiber having a length Lr optically coupled to the optical interrogator to provide reference data, wherein the optical interrogator corrects the sensed acoustic data using the reference data to provide corrected sensed acoustic data.

Drift correction in a fiber optic distributed acoustic sensing system

A method and apparatus for measuring a pressure. A pressure gauge includes a first plate having a resonant frequency related to a pressure at the pressure gauge. The first plate is thermally-excited at a selected frequency, and a sensor measures a first power level of a first light having a first wavelength reflected from the first plate and a second power level of a second light having a second wavelength reflected from the first plate. A processor determines a thermal drift in the resonant frequency of the first plate due to the thermal excitation of the first plate from the first power level and the second power level, corrects a pressure measurement determined from the resonant frequency of the first plate for the thermal drift of the resonant frequency, and operates a device based on the pressure measurement.

Quadrature detection for optical MEMS pressure gauge

Downhole fiber optic interrogation systems are described. The systems include a fiber optic control system, a first sensing system, a second sensing system, an optical fiber disposed within a well, and an optical switch arranged between the optical fiber and the first and second sensing systems, wherein the fiber optic control system performs time division multiplex control of the optical switch wherein the first sensing system is operably connected to the optical fiber and the second sensing system is not connected to the optical fiber, and further controls the optical switch such that the second sensing system is operably connected to the optical fiber and the first sensing system is not connected to the optical fiber.

Time division multiplexing of distributed downhole sensing systems

A system and method to determine temperature include an optical fiber and at least two pulse laser sources to transmit light pulses with at least two wavelengths into the optical fiber. The system also includes an optical path length modulator to modulate the optical path length of the optical fiber as the light pulses are transmitted into the optical fiber. At least two photodetectors detect backscatter reflected in the optical fiber, and a processor determines the temperature based on the backscatter.

DTS performance improvement through variable mode path length averaging

An embodiment of a system for performing measurements in a downhole environment includes an optical interrogation assembly configured to emit a pulsed optical signal, the pulsed optical signal including a selected wavelength, and an optical fiber configured to be disposed in a borehole in an earth formation and configured to receive the pulsed optical signal, the optical fiber having at least one measurement location disposed therein and configured to at least partially reflect the pulsed optical signal. The optical fiber has a core and a cladding, at least a portion of the core made from at least substantially pure silica, and the optical fiber has a refractive index profile configured to have a zero dispersion wavelength that is greater than the selected wavelength.

Dispersion-shifted optical fibers for downhole sensing

An embodiment of a system for measuring a parameter includes at least a first optical fiber and a second optical fiber configured to be disposed in one or more boreholes in an earth formation, the first optical fiber and the second optical fiber including a plurality of sensing locations. The system also includes a first light source configured to launch a first optical signal into at least the first optical fiber, and a second light source configured to launch a second optical signal into at least the second optical fiber, wherein the first optical signal and the second optical signal are launched at least substantially simultaneously. The system further includes a processor configured to receive measurement data generated based on backscattered signals from at least the first optical fiber and the second optical fiber the reflected signals, the processor configured estimate the parameter based on the measurement data.

Distributed parameter measurements using multiple optical sources

A method of measuring temperatures, includes disposing a carrier in a borehole in an earth formation, the carrier having an optical fiber connected thereto, interrogating the optical fiber with a pulsed optical signal generated by a distributed temperature sensing (DTS) assembly, the pulsed optical signal having a first frequency, and receiving first reflected signals from the optical fiber, estimating an absolute temperature from the reflected signals, interrogating the optical fiber with an at least partially coherent optical signal from a phase sensitive optical time domain reflectometry (&#x3d5;-OTDR) assembly, the at least partially coherent optical signal having a second frequency, and receiving second reflected signals from multiple scattering locations in the optical fiber; estimating a phase difference between the reflected signals, and estimating a temperature change based on the phase difference, and combining the absolute temperature and the temperature change to generate a temperature profile at a location in the borehole.

Measurement of temperature using combination of rayleigh and raman backscatter interferometry

An apparatus for sensing acoustic waves below a surface of the earth includes an optical fiber disposed below the surface of the earth and having a series of sensing units along the optical fiber with each sensing unit having three or more reflectors and an optical interrogator in optical communication with the optical fiber. The reflectors in each sensing unit are positioned to provide a linearized response that approximates a sawtooth wave better than a sinusoidal wave to sense the acoustic waves in a desired dynamic range. The optical interrogator is configured to transmit an input light signal into the optical fiber and receive a reflected light signal from the optical fiber due to the input light signal in order to measure a strain on each sensing unit due to interaction with the acoustic waves and to determine a location of the sensing unit corresponding to the sensed strain.

Optical fiber distributed sensors with improved dynamic range

An embodiment of a method of measuring temperatures includes: taking distributed acoustic sensing (DAS) measurement data by transmitting interrogation signals into an optical fiber disposed in an environment of interest, and receiving reflected signals over a selected time period from the optical fiber; processing the DAS measurement data to separate components of the DAS data associated with changes in temperature; and generating a temperature change profile for the selected time period based on the separated components of the DAS data.

Temperature sensing using distributed acoustic sensing

A distributed temperature sensor and a method of determining temperature are described. The distributed temperature sensor includes an optical fiber to filter or remove Stokes Raman scatter and prevent stimulated Raman scatter and a light source to inject light into the optical fiber. The distributed temperature sensor also includes a photodetector to detect light energy resulting from the light injected into the optical fiber, the light energy including anti-Stokes Raman scatter and Rayleigh scatter; and a processor to determine temperature based on a ratio of the anti-Stokes Raman scatter and the Rayleigh scatter.

Distributed temperature sensor enhancement by stimulated Raman suppression

A distributed temperature sensor, a method of determining temperature, and a processing system to compute temperature are described. The sensor includes an optical fiber disposed in an area where temperature is to be measured, a primary light source to inject light into the optical fiber, and a secondary light source to inject light into the optical fiber. The sensor additionally includes a photodetector to detect backscatter light energy from the optical fiber the backscatter light energy including Stokes Raman scatter or anti-Stokes Raman scatter and primary Rayleigh scatter resulting from the primary light source and secondary Rayleigh scatter resulting from the secondary light source, and a processor to determine temperature based on a ratio of the Stokes Raman scatter or the anti-Stokes Raman scatter and a combination of the primary Rayleigh scatter and the secondary Rayleigh scatter.

Attenuation correction for distrbuted temperature sensors using antistokes to rayleigh ratio

A distributed temperature sensor (DTS) system includes a light source; a length of fiber filter having been hydrogen darkened prior to assembly of the system; and a DTS fiber. A method for making a filter for a DTS system.

Filter and method and distributed temperature sensor system

A method of monitoring fluid flow in a borehole includes measuring acoustics at a plurality of locations along a downhole assembly in a borehole and calculating a fluid flow rate at the plurality of locations along the downhole assembly based on measuring the acoustics at the plurality of locations.

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Houston, TX, United States of America

William Albert Johnston