Weatherford/lamb, Inc.

USA As Represented by Secretary of the Navy

Cidra Corporation

Other

Allen R Davis

Daniel L Gysling

Charles Winston

John M Faustino

Alan D Kersey

Brandon F Redding

Mark R Fernald

Timothy J Bailey

Richard Todd Jones

Rebecca S McGuinn

Clay K Kirkendall

Michael A Davis

Douglas H Loose

Jian-Qun Wu

Robert J Maron

Guy A Daigle

Anthony Dandridge

Arthur D Hay

Bob A Hardage

Francis X Bostick, Iii

Phillip E Pruett

Peter C Ogle

Rebecca S Bryant

F Kevin Didden

Matthew J Murray

Xiaomin Zhao

Rebecca S Mcguinn

Charles R Winston

Methods and apparatuses for quantitatively measuring strain in an optical fiber. An optical source comprising an optical beam generator and a pulse generator receives instructions from a controller and generates a pulsed optical beam in response to those instructions. The pulsed optical beam is directed into an optical fiber to generate a reflected beam from scattering centers within the optical fiber. A detector records a plurality of frames of data generated by the reflected beam, and the controller tracks an evolution of a speckle pattern carried by the reflected beam from the plurality of frames and calculates a strain induced in a section of the optical fiber from the evolution of the speckle pattern.

Methods and apparatuses for quantitative sensing using Rayleigh scattering in optical fiber

Method and apparatuses for acoustic sensing using an optical fiber are provide. An optical fiber sensor for acoustic sensing includes an optical fiber, a laser, a pump laser pulse generator, a probe laser pulse generator, a controller, and a detector. The pump laser pulse generator is configured to receive a laser beam, from the laser, and generate a pump laser pulse. Similarly, the probe laser pulse generator is configured to receive the laser beam and generate a plurality of probe laser pulses. The controller is constructed to control the pump laser pulse generator and the probe laser pulse generator to inject the pump laser pulse and the plurality of probe laser pulses, respectively, into the optical fiber at specific timings so as to generate a plurality of Brillouin gratings at a predetermined spacing. The detector is configured to receive reflected pump laser pulses from the plurality of Brillouin gratings, respectively, and provide the reflected pump laser pulses to the controller. The duration of the pump laser pulse is greater than a duration of a probe laser pulse.

Methods and apparatuses for acoustic detection using temporary Brillouin gratings

A method of interferometric optical sensing via spatial demodulation includes emitting a laser beam; splitting the laser beam into a reference beam and an interrogation beam; converting a desired signal into a change in the optical path of the interrogation beam via an optical sensor; and capturing the reference beam and the interrogation beam via a camera, wherein the interrogation beam is incident to the camera at a first angle and the reference beam is incident to the camera at a second angle different from the first angle, thereby causing an interference pattern at the camera.

Advantages of spatial demodulation in interferometric optical sensing applications

Various methods are described which increase the efficiency and accuracy of a signal processor in determining parameters of a fluid using signals output by a spatial array of sensors disposed along a pipe. In one aspect, parameters used for calculating the temporal Fourier transform of the pressure signals, specifically the amount or duration of the data that the windowing function is applied to and the temporal frequency range, are adjusted in response to the determined parameter. In another aspect, an initialization routine estimates flow velocity so the window length and temporal frequency range can be initially set prior to the full array processing. In another aspect, the quality of one or more of the parameters is determined and used to gate the output of the apparatus in the event of low confidence in the measurement and/or no flow conditions. In another aspect, a method for determining a convective ridge of the pressure signals in the k-&#x3c9; plane is provided.

Method and apparatus for measuring a parameter of a fluid flowing within a pipe using an array of sensors

A fiber optic pressure sensor for measuring unsteady pressures within a pipe include at least one optical fiber disposed circumferentially around a portion of a circumference of the pipe, which provides an optical signal indicative of the length of the optical fiber. An optical instrument measures the change in length of the optical fiber to determine the unsteady pressure within the pipe. The pressure sensor may include a plurality of optical fiber sections disposed circumferentially around a portion of the circumference of the pipe that are optically connected together by optical fiber sections disposed axially along the pipe. The optical fiber sections may include fiber Bragg gratings having substantially the same or different reflection wavelengths to permit for example the sensors to be axially distributed along the fiber using wavelength division multiplexing and/or time division multiplexing.

Apparatus and method having an optical fiber disposed circumferentially around the pipe for measuring unsteady pressure within a pipe

An apparatus and method for interrogating fiber optic sensors non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes a two-beam interferometer which comprises an optical circuit for generating a series of discrete light pulses that are directed at sensors positioned between pairs of low reflectivity fiber Bragg gratings. The successive light pulses are split into first light pulses and second light pulses, and the second light pulses are delayed a known time period relative to the first pulses. The first and second light pulses are combined onto a single optical fiber and directed through the low reflectivity gratings and the sensors positioned between the gratings. Reflected pulses from the series of pulses impinge on a photo receiver and interrogator, wherein the phase shift between the reflected first light pulses from a particular grating and the reflected second light pulses from the preceding grating, for each sensor are determined. Phase shifts from successive pulses for each sensor are compared, and a change in a measured parameter of the fluid is determined.

Method and apparatus for interrogating fiber optic sensors

An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes a first sensing array for sensing acoustic signals traveling at the speed of sound through fluid flow within the pipe, a second sensing array for sensing local pressure variations traveling with the fluid flow, and a housing attached to the pipe for enclosing the sensing arrays. The first sensing array includes a plurality of first optical pressure sensors and the second sensing array includes a plurality of second optical pressure sensors.

Apparatus for sensing fluid in a pipe

The present invention provides a new and unique method, sensor, and apparatus for performing a seismic survey of an earth formation in relation to a borehole. The method includes arranging at least one strain seismic sensor in conjunction with a borehole structure, and mechanically coupling the borehole structure to the borehole to allow seismic data to be accurately transferred to the sensor. The sensor is preferably a fiber optic sensor, including a Fiber Bragg Grating which may be coupled to a relevant borehole structure in a number of ways.

Method and apparatus for seismically surveying an earth formation in relation to a borehole

An apparatus for sensing the temperature of a fluid being drawn from a well includes a pipe having a wall, a sensor mounted on the outer surface of the pipe wall, an insulator, and a housing attached to the pipe that encloses the sensor and the insulator. The fluid to be sensed is drawn from the well through the pipe. The thermal conductivity of the pipe wall is greater than that of the insulator.

Non-intrusive temperature sensor for measuring internal temperature of fluids within pipes

An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes an array of sensors that include a plurality of optical fiber coils. The array of sensors senses the fluid flow inside the pipe. At least one optical reflective device is disposed between adjacent optical fiber coils. An isolation pad is disposed between each optical reflective device and the pipe.

Isolation pad for protecting sensing devices on the outside of a conduit

Non-intrusive pressure sensors for measuring unsteady pressures within a pipe include an optical fiber wrapped in coils around the circumference of the pipe . The length or change in length of the coils is indicative of the unsteady pressure in the pipe. Bragg gratings impressed in the fiber may be used having reflection wavelengths &lgr; that relate to the unsteady pressure in the pipe. One or more of sensors may be axially distributed along the fiber using wavelength division multiplexing and/or time division multiplexing.

Non-intrusive fiber optic pressure sensor for measuring unsteady pressures within a pipe

A fiber optic Bragg grating pressure sensor particularly suited for measuring ambient pressure of a fluid includes a pressuring detecting device,such as a glass element whose elastic deformation is proportional to applied pressure. An optical fiber,with an integral first grating,is wrapped at least once around the device and has at least a portion of its length fused to the device,such that elastic deformation of the device,generates a corresponding axial strain in the fiber,and/or the grating,and thus a corresponding change of the fiber length and/or characteristic reflectance wavelength of the grating,. A second grating,may be formed near the pressure detecting device,so as to sense ambient temperature but not be affected by deformation of the device,for temperature compensation. Also, the fiber,may have more than one grating or be doped at least between a pair of gratings,, to form a fiber laser or a DFB fiber laser which lasing wavelength changes with changing pressure.

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Falls Church, VA, United States of America

Allen R Davis