Abstract: Methods and apparatus for automatic recognition of environmental parameters with azimuthally distributed transducers. For example, a toolstring is disposed in a cased portion of a borehole penetrating a subsurface formation. The toolstring comprises a module comprising azimuthally distributed acoustic transducers each operable to emit and receive acoustic signals. The module is operated to emit an acoustic signal into fluid surrounding the module in the casing and record data indicative of receipt, by a plurality of the transducers, of acoustic waveforms resulting from interaction of the emitted acoustic signal with the casing, including at least a non-specular diffraction head wave excited by a guided wave that is excited by diffraction of the acoustic signal propagating in the casing metal. Acoustic velocity of the guided wave in the casing metal is determined utilizing the recorded data and geometric parameters of the module.

Abstract: Methods and apparatus for automatic recognition of environmental parameters with azimuthally distributed transducers. For example, a toolstring is disposed in a cased portion of a borehole penetrating a subsurface formation. The toolstring comprises a module comprising azimuthally distributed acoustic transducers each operable to emit and receive acoustic signals. The module is operated to emit an acoustic signal into fluid surrounding the module in the casing and record data indicative of receipt, by a plurality of the transducers, of acoustic waveforms resulting from interaction of the emitted acoustic signal with the casing, including at least a non-specular diffraction head wave excited by a guided wave that is excited by diffraction of the acoustic signal propagating in the casing metal. Acoustic velocity of the guided wave in the casing metal is determined utilizing the recorded data and geometric parameters of the module.

Abstract: Systems, methods, and computer-readable media for evaluating annular material using beamforming from acoustic arrays are provided. A logging tool may include one or more acoustic phased arrays, such as one or more transmitter arrays and one or more receiver arrays each having multiple transducer elements. The acoustic signals may be beamformed by independently pulsing array elements of the arrays to excite and detect desired wave modes in a casing or other material in a well. Parameters of the casing or other material in the well may be determined using the received acoustic signal.

Abstract: A method of determining properties of a wellbore in a formation includes obtaining from the acoustic logging tool, acoustic data comprising an acoustic wave reflected from the casing, the annular fill material, one or more interfaces between any of the mud, the casing, and the annular fill material, or combinations thereof. The method includes normalizing the acoustic wave in a frequency domain, resulting in a specular spectrum and removing spectral noise outside a region of interest in the specular spectrum. The method includes shaping the specular spectrum around a resonance frequency, converting the shaped specular spectrum into a time domain, resulting in a renormalized waveform, and subtracting from the renormalized waveform one or more of a specular noise, second interface echoes, resulting in a third interface echo signal.

Abstract: Systems, methods, and computer-readable media for determining shear-wave to compressional-wave velocity ratios in well casings are provided. A logging tool may include one or more acoustic phased arrays, such as one or more transmitter arrays and one or more receiver arrays each having multiple transducer elements. Peak pulse amplitudes may be calculated from received acoustic signals, and the group velocity of the peak mode may be calculated. The peak amplitude from measurements over a suitable incidence angle range may be used to determine the value of the shear-wave to compressional-wave velocity ratio.

Abstract: Methods for separating flexural and extensional mode signals from a multi-modal signal are provided. In one embodiment, a method includes emitting an ultrasonic pulse to excite a multi-modal Lamb wave in a pipe and then detecting acoustic signals generated from the Lamb wave. The detected acoustic signals are processed to separate the extensional and flexural mode signals. This processing can include filtering the detected acoustic signals with filters that are based on quality factors and dispersion characteristics for the individual modes to produce sets of coefficients, selecting subsets of the coefficients, and using the selected subsets to predict extensional and flexural mode waveforms that are based on the estimated quality factors for the individual modes. Additional methods, systems, and devices are also disclosed.

Abstract: A method of determining properties of a wellbore in a formation includes obtaining from the acoustic logging tool, acoustic data comprising an acoustic wave reflected from the casing, the annular fill material, one or more interfaces between any of the mud, the casing, and the annular fill material, or combinations thereof. The method includes normalizing the acoustic wave in a frequency domain, resulting in a specular spectrum and removing spectral noise outside a region of interest in the specular spectrum. The method includes shaping the specular spectrum around a resonance frequency, converting the shaped specular spectrum into a time domain, resulting in a renormalized waveform, and subtracting from the renormalized waveform one or more of a specular noise, second interface echoes, resulting in a third interface echo signal.

Abstract: Systems, methods, and computer-readable media for determining shear-wave to compressional-wave velocity ratios in well casings are provided. A logging tool may include one or more acoustic phased arrays, such as one or more transmitter arrays and one or more receiver arrays each having multiple transducer elements. Peak pulse amplitudes may be calculated from received acoustic signals, and the group velocity of the peak mode may be calculated. The peak amplitude from measurements over a suitable incidence angle range may be used to determine the value of the shear-wave to compressional-wave velocity ratio.

Abstract: Systems, methods, and computer-readable media for evaluating annular material using beamforming from acoustic arrays are provided. A logging tool may include one or more acoustic phased arrays, such as one or more transmitter arrays and one or more receiver arrays each having multiple transducer elements. The acoustic signals may be beamformed by independently pulsing array elements of the arrays to excite and detect desired wave modes in a casing or other material in a well. Parameters of the casing or other material in the well may be determined using the received acoustic signal.

Abstract: Techniques involve methods and systems for separating leaky-Lamb modes to evaluate cylindrically layered structures. Embodiments involve receiving acoustic cement evaluation data from one or more acoustic downhole tools used over a depth interval in a well having a casing. The acoustic cement evaluation data includes leaky-Lamb wave measurements measured from the acoustic downhole tools. Embodiments also involve determining an extensional mode component and a flexural mode component of the leaky-Lamb wave measurements and determining a flexural wave attenuation based on the flexural mode component of the leaky-Lamb wave measurement. In some embodiments, the extensional and flexural mode components can be determined using mode decomposition technique.