Abstract: 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.

Abstract: 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-? plane is provided.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Non-intrusive pressure sensors 14-18 for measuring unsteady pressures within a pipe 12 include an optical fiber 10 wrapped in coils 20-24 around the circumference of the pipe 12. The length or change in length of the coils 20-24 is indicative of the unsteady pressure in the pipe. Bragg gratings 310-324 impressed in the fiber 10 may be used having reflection wavelengths &lgr; that relate to the unsteady pressure in the pipe. One or more of sensors 14-18 may be axially distributed along the fiber 10 using wavelength division multiplexing and/or time division multiplexing.

Abstract: 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.

Abstract: Non-intrusive pressure sensors 14-18 for measuring unsteady pressures within a pipe 12 include an optical fiber 10 wrapped in coils 20-24 around the circumference of the pipe 12. The length or change in length of the coils 20-24 is indicative of the unsteady pressure in the pipe. Bragg gratings 310-324 impressed in the fiber 10 may be used having reflection wavelengths &lgr; that relate to the unsteady pressure in the pipe. One or more of sensors 14-18 may be axially distributed along the fiber 10 using wavelength division multiplexing and/or time division multiplexing.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 optics 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 sensor 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 the second grating and the reflected second light pulses from the first grating for each sensor are determined.

Abstract: A fiber optic Bragg grating pressure sensor particularly suited for measuring ambient pressure of a fluid includes a pressuring detecting device 12 such as a glass element whose elastic deformation is proportional to applied pressure. An optical fiber 28 with an integral first grating 33 is wrapped at least once around the device and has at least a portion of its length fused to the device 12 such that elastic deformation of the device 12 generates a corresponding axial strain in the fiber 28 and/or the grating 33 and thus a corresponding change of the fiber length and/or characteristic reflectance wavelength of the grating 33. A second grating 35 may be formed near the pressure detecting device 12 so as to sense ambient temperature but not be affected by deformation of the device 12 for temperature compensation.

Abstract: A gunnable plastic refractory is made by adding a hydrocolloid, for example a polysaccharide ether such as methylcellulose, to the refractory composition and adjusting the moisture content to be from about 4% to about 10%. The workability index of the refractory mix is from about 8% to about 30%. The refractory can be gunned without stoppages caused by clogging of hoses and the rebound rate is low.

Abstract: A gunnable plastic refractory is made by adding a polysaccharide ether such as methylcellulose to the refractory composition and adjusting the moisture content to be from about 4% to about 10%. The workability index of the refractory mix is from about 8% to about 30%. The refractory is gunned without stoppages caused by clogging of hoses and the rebound rate is low.