Abstract: Disclosed are systems and methods for processing broadband acoustic signals acquired by a plurality of acoustic sensors, using an array-signal-processing technique to compute fused-signal maps in the frequency domain for a plurality of frequency bins. In accordance with various embodiments, the fused-signal maps are combined across the frequency bins, with respective weightings that are based on eigenvalues of covariance matrices computed for the plurality of frequency bins. The combined maps can be used to locate an acoustic source in a wellbore.

Abstract: Acoustic characterization and mapping of flow from a perforation zone of a well. As a wireline probe containing acoustic sensors moves through the well, the acoustic sensors record acoustic pressure measurements of flow for each perforation in the well casing. The acoustic data is recorded and compiled into a three-dimensional flow model showing flow of hydrocarbons within and/or out of perforation tunnels. The three-dimensional flow models generated can be combined with historical data to form four-dimensional models illustrating flow over time, and both the three and four-dimensional models can be used to determine effectiveness of perforation charges as well as future flow from the well.

Abstract: Disclosed are acoustic logging systems and methods that involve correlating broadband acoustic signals acquired by a plurality of acoustic sensors at multiple depths within a wellbore to compute covariance matrices and their eigenvalues in the frequency domain for a plurality of frequency bins. In accordance with various embodiments, acoustic sources are detected and located based on the eigenvalues viewed as a function of depth and frequency.

Abstract: Disclosed are tools, systems, and methods for detecting one or more underground acoustic sources and localizing them in depth and radial distance from a wellbore, for example, for the purpose of finding underground fluid flows, such as may result from leaks in the well barriers. In various embodiments, acoustic-source detection and localization are accomplished with an array of at least three acoustic sensors disposed in the wellbore, in conjunction with array signal processing.

Abstract: Described herein are tools, systems, and methods for detecting, classifying, and/or quantifying underground fluid flows based on acoustic signals emanating therefrom, using a plurality of acoustic sensors disposed in the wellbore in conjunction with array signal processing and systematic feature-based classification and estimation methods.

Abstract: Disclosed are acoustic logging systems and methods that involve correlating broadband acoustic signals acquired by a plurality of acoustic sensors at multiple depths within a wellbore to compute covariance matrices and their eigenvalues in the frequency domain for a plurality of frequency bins. In accordance with various embodiments, acoustic sources are detected and located based on the eigenvalues viewed as a function of depth and frequency.

Abstract: Various apparatus or methods are arranged to operate a tool in a wellbore, where the tool has a number of acoustic sensors. Scanning images obtained by the tool sensors along the borehole can be combined to increase the contrast of leak location with respect to background noise. A sequence of beamformed images, generated from signals captured by the tool as it moves over a range of depths of the wellbore, can be acquired. Each beamformed image may overlap at least one other beamformed image of the sequence. The beamformed images can be processed and the processed beamformed images can be combined, forming a stitched image. Additional apparatus, systems, and methods operable in providing stitched images can operate in a variety of applications.

Abstract: A method for operation of an acoustic tool, having a plurality of acoustic sensors, may include receiving acoustic waves from an acoustic source located at a depth in a borehole. A selected location (e.g., central location) of the acoustic sensor array may be positioned substantially at the depth of the acoustic source based on a symmetricity of an upper and lower section of a frequency-wavenumber (f-k) transform pattern with respect to a selected wavenumber. A radial distance from the acoustic source to the acoustic tool may be determined based on a theoretical f-k transform pattern used as a mask to filter measured data in the f-k domain.

Abstract: The disclosed embodiments include leak detection systems and methods of downhole leak detection. In one embodiment, the method includes obtaining physical signals measured by at least one physical sensor traveling along a wellbore. The method also includes performing a frame decomposition operation on the physical signals of a first of the at least one the physical sensor to obtain a plurality of virtual signals associated with an array of virtual sensors, each virtual sensor of the array of virtual sensors being located at a virtual distance relative to the first physical sensor, the virtual distance corresponding to a physical distance. The method further includes synchronizing the virtual signals of the array of virtual sensors. The method further includes computing a spatial spectrum indicative of a location of a leak based on the synchronized virtual signals.

Abstract: Acoustic characterization and mapping of flow from a perforation zone of a well. As a wireline probe containing acoustic sensors moves through the well, the acoustic sensors record acoustic pressure measurements of flow for each perforation in the well casing. The acoustic data is recorded and compiled into a three-dimensional flow model showing flow of hydrocarbons within and/or out of perforation tunnels. The three-dimensional flow models generated can be combined with historical data to form four-dimensional models illustrating flow over time, and both the three and four-dimensional models can be used to determine effectiveness of perforation charges as well as future flow from the well.

Abstract: A distributed acoustic sensing cable including an optical fiber waveguide configured to provide light signal transmission and an acoustic device coupled to the optical fiber waveguide and configured to provide acoustic signal transmission. The acoustic device includes a polymer composite having reinforced fibers embedded therein. The polymer composite having acoustic waveguides for attenuating undesirable acoustic waves propagating along the distributed acoustic sensing cable and optical fibers embedded within the polymer composite that extend along an axial length of the acoustic device that facilitate the light signal transmission.

Abstract: Disclosed are systems and methods for processing broadband acoustic signals acquired by a plurality of acoustic sensors, using an array-signal-processing technique to compute fused-signal maps in the frequency domain for a plurality of frequency bins. In accordance with various embodiments, the fused-signal maps are combined across the frequency bins, with respective weightings that are based on eigenvalues of covariance matrices computed for the plurality of frequency bins. The combined maps can be used to locate an acoustic source in a wellbore.

Abstract: The disclosed embodiments include leak detection systems and methods of downhole leak detection. In one embodiment, the method includes obtaining physical signals measured by at least one physical sensor traveling along a wellbore. The method also includes performing a frame decomposition operation on the physical signals of a first of the at least one the physical sensor to obtain a plurality of virtual signals associated with an array of virtual sensors, each virtual sensor of the array of virtual sensors being located at a virtual distance relative to the first physical sensor, the virtual distance corresponding to a physical distance. The method further includes synchronizing the virtual signals of the array of virtual sensors. The method further includes computing a spatial spectrum indicative of a location of a leak based on the synchronized virtual signals.

Abstract: Various apparatus or methods are arranged to operate a tool in a wellbore, where the tool has a number of acoustic sensors. Scanning images obtained by the tool sensors along the borehole can be combined to increase the contrast of leak location with respect to background noise. A sequence of beamformed images, generated from signals captured by the tool as it moves over a range of depths of the wellbore, can be acquired. Each beamformed image may overlap at least one other beamformed image of the sequence. The beamformed images can be processed and the processed beamformed images can be combined, forming a stitched image. Additional apparatus, systems, and methods operable in providing stitched images can operate in a variety of applications.

Abstract: A method for operation of an acoustic tool, having a plurality of acoustic sensors, may include receiving acoustic waves from an acoustic source located at a depth in a borehole. A selected location (e.g., central location) of the acoustic sensor array may be positioned substantially at the depth of the acoustic source based on a symmetricity of an upper and lower section of a frequency-wavenumber (f-k) transform pattern with respect to a selected wavenumber. A radial distance from the acoustic source to the acoustic tool may be determined based on a theoretical f-k transform pattern used as a mask to filter measured data in the f-k domain.

Abstract: A measurement assembly for determining an electrical resistance of a fluid in a wellbore is provided. The measurement assembly can include a non-conductive frame, comprising an excitation electrode and a monitoring electrode coupled to the non-conductive frame. The measurement assembly can also include a central electrode in a flow path for the fluid, wherein the flow path is defined by the non-conductive frame. The central electrode can be positioned for conductively coupling the excitation electrode and the monitoring electrode through a conductive path defined by the fluid. Further, the measurement assembly can include a power source for transmitting power to the excitation electrode for determining the electrical resistance of the fluid. The electrical resistance of the fluid can be used to determine whether the fluid includes oil, water, or gas.

Abstract: Described herein are tools, systems, and methods for detecting, classifying, and/or quantifying underground fluid flows based on acoustic signals emanating therefrom, using a plurality of acoustic sensors disposed in the wellbore in conjunction with array signal processing and systematic feature-based classification and estimation methods.

Abstract: Disclosed are tools, systems, and methods for detecting one or more underground acoustic sources and localizing them in depth and radial distance from a wellbore, for example, for the purpose of finding underground fluid flows, such as may result from leaks in the well barriers. In various embodiments, acoustic-source detection and localization are accomplished with an array of at least three acoustic sensors disposed in the wellbore, in conjunction with array signal processing.

Abstract: A distributed acoustic sensing cable including an optical fiber waveguide configured to provide light signal transmission and an acoustic device coupled to the optical fiber waveguide and configured to provide acoustic signal transmission. The acoustic device includes a polymer composite having reinforced fibers embedded therein. The polymer composite having acoustic waveguides for attenuating undesirable acoustic waves propagating along the distributed acoustic sensing cable and optical fibers embedded within the polymer composite that extend along an axial length of the acoustic device that facilitate the light signal transmission.

Abstract: A method of generating linear models for a physical system of interest is implemented in steps including, first, determining offline, a set of linear models for the physical system of interest by linearization of a nonlinear computational model of the physical system of interest at selected operating points or from desired data; second, analyzing offline, accuracy of each linear model and eliminating inaccurate linear models therefrom to provide a residual set of linear models; third, generating offline, linear models corresponding to grid points of one or more lookup tables based on the residual set of linear models; fourth, associating offline, lookup table grid points with selected scheduling variables, and fifth, generating algorithmic software for the physical system therefrom such that linear models for the physical system generated offline form the basis for online scheduling of linear models.