Abstract: Described are methods and systems using optical fiber interferometry to sense interference causing events in a region of interest and differentiate between a strain event and a thermal event. Other methods and systems relate to the use of optical fiber interferometry for determining temperature offset in a region of interest and using the determined temperature offset for determining temperature in the region of interest.

Abstract: Sensor shaped to have a frequency response that has less spectral fading than a sensor with a rectangular wrapping pattern, and methods for making such sensors, are disclosed. One such method includes selecting a wrapping pattern comprising multiple layers in which a top layer has a different length than a bottom layer and where the bottom layer is adjacent a mandrel. The method further includes wrapping optical fiber around the mandrel according to the wrapping pattern.

Abstract: A system and method for detecting dynamic strain of a housing. The system includes an optical fiber linearly affixed along a surface of a length of the housing and an interrogator comprising a laser source and a photodetector. The optical fiber comprises at least one pair of fiber Bragg gratings (FBGs) tuned to reflect substantially identical wavelengths with a segment of the optical fiber extending between the FBGs. The segment of the optical fiber is linearly affixed along the surface of the housing. The interrogator is configured to perform interferometry by shining laser light along the optical fiber and detecting light reflected by the FBGs. The interrogator outputs dynamic strain measurements based on interferometry performed on the reflected light.

Abstract: Methods, systems, and techniques for determining whether an event has occurred from dynamic strain measurements involve determining, using a processor, at least one event parameter from a signal representing the dynamic strain measurements, and then having the processor use the at least one event parameter to determine whether the event has occurred. The at least one event parameter is any one or more of a measure of magnitude of the signal, frequency centroid of the signal, filtered baseline of the signal, harmonic power of the signal, and time-integrated spectrum flux of the signal.

Abstract: An apparatus for detecting acoustic signals in housing is disclosed. The housing may be housing of a wellbore, riser, tubular or pipeline or the like for transporting fluids or housing of a vessel for storing fluids. The apparatus comprises a longitudinally extending tube having an internal surface and an external surface, a longitudinally extending fiber optic cable disposed within the tube, and one or more than one longitudinally extending outer fins radially extending outwards from and coupled with the external surface of the tube. The outer fin is configured to project towards the housing and allows fluid between the external surface of the tube and the housing when the apparatus is positioned in the housing. The apparatus may alternatively comprise a longitudinally extending fiber optic cable coated with a coating and one or more than one longitudinally extending outer fin radially extending outwards from and coupled with the coated fiber optic cable.

Abstract: A method for non-intrusive pipeline testing involves constructing the pipeline at a construction location that is above ground, affixing an optical fiber along a surface of a length of the pipeline that is at the construction location, measuring dynamic strain experienced by the length of the pipeline by performing optical interferometry using the optical fiber, and moving the length of the pipeline from the construction location to a different installation location. The optical fiber includes at least one pair of fiber Bragg gratings (“FBGs”) tuned to reflect substantially identical wavelengths with a segment of the optical fiber extending between the FBGs.

Abstract: There is described a method for interrogating optical fiber comprising fiber Bragg gratings (“FBGs”), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.

Abstract: Various embodiments provide a method of simulating a leak in a pipeline. The method includes: receiving a fluid stream from a fluid supply; and outputting the received fluid stream through an outlet such that the received fluid stream hits an outer surface of the pipeline at a location opposite the outlet such that a vibration is caused in the pipeline. Some other embodiments provide a corresponding system for simulating a leak in a pipeline, and a corresponding outlet for coupling a conduit to a pipeline.

Abstract: Methods and systems for estimating a distance between an acoustic sensor and an acoustic reflector in a conduit are disclosed. One such method includes using the acoustic sensor to measure a combined acoustic signal that comprises an originating acoustic signal propagating along the conduit and an echo signal. The echo signal is generated by the originating acoustic signal reflecting off the acoustic reflector after propagating past the acoustic sensor. A frequency domain representation of the combined acoustic signal is determined and the echo signal is identified by identifying in the frequency domain representation periodic oscillations having a peak-to-peak difference between 0.75 Hz and 1500 Hz. The distance between the acoustic sensor and the acoustic reflector is determined from the velocity of the echo signal and a time required for the echo signal to propagate between the acoustic sensor and the acoustic reflector.

Abstract: A clamp for clamping optical fiber to a tube. The clamp has a body portion coupled at one end to a first arm and at an opposing end to a second arm, and a resilient portion to permit the clamp to elastically deform from a closed state in which the clamp is fastened around the tube to an open state in which the clamp is radially moveable off the tube. At least one of the body portion, the first arm and the second arm has a clamping surface to clamp a portion of the optical fiber against the tube when the clamp is fastened around the tube, and a clamping mechanism operable to extend at least part of the clamping surface towards the tube when the clamp is secured to the tube to increase a clamping force applied by the clamping surface.

Abstract: Sensor shaped to have a frequency response that has less spectral fading than a sensor with a rectangular wrapping pattern, and methods for making such sensors, are disclosed. One such method includes selecting a wrapping pattern comprising multiple layers in which a top layer has a different length than a bottom layer and where the bottom layer is adjacent a mandrel. The method further includes wrapping optical fiber around the mandrel according to the wrapping pattern.

Abstract: Described are methods and systems using optical fiber interferometry to sense interference causing events in a region of interest and differentiate between a strain event and a thermal event. Other methods and systems relate to the use of optical fiber interferometry for determining temperature offset in a region of interest and using the determined temperature offset for determining temperature in the region of interest.

Abstract: A system and method for detecting dynamic strain of a housing. The system includes an optical fiber linearly affixed along a surface of a length of the housing and an interrogator comprising a laser source and a photodetector. The optical fiber comprises at least one pair of fiber Bragg gratings (FBGs) tuned to reflect substantially identical wavelengths with a segment of the optical fiber extending between the FBGs. The segment of the optical fiber is linearly affixed along the surface of the housing. The interrogator is configured to perform interferometry by shining laser light along the optical fiber and detecting light reflected by the FBGs. The interrogator outputs dynamic strain measurements based on interferometry performed on the reflected light.

Abstract: A device and system for detecting dynamic strain. The device comprises a longitudinally extending carrier and an optical fiber embedded along an outer surface of a length of the carrier. The optical fiber comprises at least one pair of fiber Bragg gratings (FBGs) tuned to reflect substantially identical wavelengths. The system comprises the device and an interrogator comprising a laser source and a photodetector. The interrogator is configured to perform interferometry by shining laser light along the optical fiber and detecting light reflected by the FBGs. The interrogator outputs dynamic strain measurements based on interferometry performed on the reflected light.

Abstract: A method for determining relative location of an acoustic event along a channel such as a wellbore includes obtaining two acoustic signals at are obtained at two different and known depths in the wellbore, dividing the acoustic signals into windows, and determining the relative loudnesses of pairs of the windows. The power of the acoustic signals may be used as a proxy for the loudness of the acoustic event, and this determination can be made in the time or frequency domains. The relative depth of the acoustic event can then be determined relative to the two known depths from the relative loudnesses. The acoustic event may be, for example, casing vent flow, gas migration, a leak along a pipeline, or sounds observed in an observation well from a nearby well in which fracking is being performed.

Abstract: The present disclosure is directed at a method and system for determining relative depth of an acoustic event within a wellbore. The method includes obtaining two acoustic signals at two different and known depths in the wellbore, in which each of the acoustic signals includes the acoustic event; dividing each of the acoustic signals into windows; determining cross-correlations of pairs of the windows, in which each of the pairs includes one window from one of the acoustic signals and another window from the other of the acoustic signals that at least partially overlap each other in time; and determining the relative depth of the acoustic event relative to the two known depths from the cross-correlations. The acoustic event may represent, for example, fluid flowing from formation into the wellbore (or vice-versa) or fluid flowing across any casing or tubing located within the wellbore.

Abstract: Coated optical fibers and uses of such fibers as sensors in high temperature and/or high pressure environments. The coated optical fiber has improved sensing properties at elevated pressure and/or temperature, such as enhanced acoustic sensitivity and/or a reduced loss in acoustic sensitivity. The use of the coated optical fibers in various sensing applications that require operation under elevated pressure and/or temperature, such as, acoustic sensors for various geological, security, military, aerospace, marine, and oil and gas applications are also provided.

Abstract: A sound baffle device for use with an acoustic sensor deployed in a housing by a deployment line is disclosed. The sound baffle device comprises a radially extending baffle plate and an affixing mechanism for affixing the baffle plate to the deployment line. The baffle plate is configured to reduce acoustic transmission between a first zone of the housing on one side of the baffle plate and a second zone of the housing on an opposite side of the baffle plate. A system for detecting acoustic signals in a zone of interest in a housing is also disclosed. The system comprises an acoustic sensor positioned in the zone of interest and one or more than one sound baffle positioned between the zone of interest and a first zone of the housing. The sound baffle is configured to reduce acoustic transmission from the first zone to the zone of interest.

Abstract: The present disclosure is directed at a method and system for determining relative depth of an acoustic event within a wellbore. The method includes obtaining two acoustic signals at two different and known depths in the wellbore, in which each of the acoustic signals includes the acoustic event; dividing each of the acoustic signals into windows; determining cross-correlations of pairs of the windows, in which each of the pairs includes one window from one of the acoustic signals and another window from the other of the acoustic signals that at least partially overlap each other in time; and determining the relative depth of the acoustic event relative to the two known depths from the cross-correlations. The acoustic event may represent, for example, fluid flowing from formation into the wellbore (or vice-versa) or fluid flowing across any casing or tubing located within the wellbore.

Abstract: A method for determining relative location of an acoustic event along a channel such as a wellbore includes obtaining two acoustic signals at are obtained at two different and known depths in the wellbore, dividing the acoustic signals into windows, and determining the relative loudnesses of pairs of the windows. The power of the acoustic signals may be used as a proxy for the loudness of the acoustic event, and this determination can be made in the time or frequency domains. The relative depth of the acoustic event can then be determined relative to the two known depths from the relative loudnesses. The acoustic event may be, for example, casing vent flow, gas migration, a leak along a pipeline, or sounds observed in an observation well from a nearby well in which fracking is being performed.