Abstract: A system can receive downhole acquisition data relating to a wellbore. The system can pre-process the downhole acquisition data. The system can generate an incomplete borehole image using the downhole acquisition data. The system can determine a sparse representation based on the incomplete borehole image by performing an optimization with respect to the incomplete borehole image. The system can generate a complete borehole image based on an inverse of the sparse representation.

Abstract: A method and system for identifying bonding between a material and tubing. The method may include disposing an acoustic logging tool in a wellbore, wherein the acoustic logging tool comprises a transmitter, a receiver, or a transceiver, broadcasting a shaped signal with the transmitter such that the shaped signal interacts with a boundary of a casing and a material and recording a result signal from the boundary with the receiver. The method may further comprise identifying a cut-off time to be applied to the result signal, transforming the result signal from a time domain to a frequency domain, selecting one or more modes sensitive to a bonding at the boundary between the casing and the material, computing a decay rate of the one or more modes that were selected based at least one or more decay curves, and converting the decay rate to a bonding log.

Abstract: Methods to perform through tubing cement evaluation using converted multipole resonance modes. A first acoustic transmission is emitted outward toward the cement such that a portion of the first acoustic transmission penetrates the cement. The receiver array detects the first acoustic response derived from the first acoustic transmission. The system then determines the multimode wellbore resonance based on the first acoustic response. In response to the first acoustic transmission penetrating the cement, a first mode of the multimode wellbore resonance is converted into a second mode different from the first mode. The receiver array detects a second acoustic response derived from the converted mode of the multimode wellbore resonance. The system determines the converted mode using the second acoustic response. A property of the cement is evaluated based on the multimode wellbore resonance and the converted mode.

Abstract: A method and system for removing intrinsic transducer noises. The method may comprise disposing a measurement assembly into a wellbore, performing a measurement operation at a depth in the wellbore with the measurement assembly to record two or more raw reflected waveforms, identifying one or more intrinsic transducer noises in the two or more raw reflected waveforms, dividing the two or more raw reflected waveforms into one or more subsections, and identifying one or more incoherent measurements in the one or more subsections. The method may further comprise deriving a noise model for each of the one or more incoherent measurements, performing an inversion for each noise model, and applying an adaptive subtraction to remove the one or more intrinsic transducer noises from the two or more raw reflected waveforms.

Abstract: In some embodiments, a method includes conveying a downhole tool in a tubing, positioned in a casing which forms an annulus between the casing and a wellbore formed in a subsurface formation, the downhole tool having a rotatable transmitter and a receiver array. The method includes performing the following until an acoustic transmission has been emitted for each of a number of defined azimuthal positions: rotating the rotatable transmitter to one of the number of defined azimuthal positions, emitting the acoustic transmission, and detecting, by the receiver array and without rotation of the downhole tool beyond a rotation threshold, an acoustic response of a number of acoustic responses that is derived from the acoustic transmission. The method further includes computationally rotating, by a processor and after detecting, data of each of the number of acoustic responses in a pre-determined direction to generate a computationally rotated multipole response.

Abstract: A system can apply an unsupervised machine-learning model to ultrasonic waveform data received about a wellbore for identifying channels in the wellbore. A system can receive ultrasonic waveform data about a wellbore using an arrangement of transducers positionable in the wellbore. The ultrasonic waveform data can include a set of ultrasonic waveforms. The system can generate a set of attributes for each ultrasonic waveform of the set of ultrasonic waveforms. The system can apply an unsupervised machine-learning model to the set of ultrasonic waveforms for clustering the set of attributes of ultrasonic waveform into a set of clusters. The system can output the set of clusters for categorizing the ultrasonic waveform data.

Abstract: A method comprises conveying a downhole tool in a production tubing within a casing that is around a wall of a wellbore formed in a subsurface formation, wherein cement is placed in an annulus defined between the casing and the wall of the wellbore. The downhole tool includes at least one unipole receiver and a transmitter that comprises at least one of a unipole transmitter and a monopole transmitter. The transmitter and receiver are mounted on a rotatable portion of the downhole tool. The method includes performing the following operations at at least two azimuthal positions, emitting an acoustic transmission outward toward the cement and detecting an acoustic response that is in response to the acoustic transmission propagating through the production tubing and the casing and into the cement. The acoustic response includes casing extensional waves, casing non-extensional waves, and tubing waves. The method includes evaluating the cement based on the casing extensional waves.

Abstract: A method comprising: conveying a downhole tool in a tubing that is positioned in a casing that is positioned to form an annulus between the casing and a wall of a wellbore formed in a subsurface formation, wherein a cement with unknown bonding condition exists in the annulus, wherein the downhole tool includes at least one transmitter and a receiver array physically positioned in different azimuthal directions; emitting, from the at least one transmitter, a first and second acoustic transmissions in a first and second azimuthal directions; detecting, by the receiver array, a first acoustic response and a second acoustic response that is derived from the first and second acoustic transmissions, wherein the second azimuthal direction is orthogonal to the first azimuthal direction; determining a dipole wellbore resonance based on the first and acoustic responses; and evaluating a property of the cement based on the dipole wellbore resonance.

Abstract: The disclosure presents processes to determine the direction and magnitude of tubing eccentricity along the length of a tube inserted within a borehole. The tubing can be a wireline, a drill string, a drill pipe, or tubing capable of allowing fluid or other material to flow through it. As borehole operations proceed, the tubing can move toward the side of the borehole. This eccentricity can cause excess wear and tear on the tubing, on the casing of the borehole, or on the inner surface of the subterranean formation. The eccentricity can be measured using acoustic signals that are collected downhole covering the azimuthal angles 0° to 360° at a location in the borehole. The collected signals can be filtered, transformed, and analyzed to estimate the tubing eccentricity. Other processes and systems can use the results to obtain cement bond evaluations through tubing and to determine preventative or restorative actions.

Abstract: A system can receive downhole acquisition data relating to a wellbore. The system can pre-process the downhole acquisition data. The system can generate an incomplete borehole image using the downhole acquisition data. The system can determine a sparse representation based on the incomplete borehole image by performing an optimization with respect to the incomplete borehole image. The system can generate a complete borehole image based on an inverse of the sparse representation.

Abstract: A method and system for identifying bonding between a material and tubing. The method may include disposing an acoustic logging tool in a wellbore, wherein the acoustic logging tool comprises a transmitter, a receiver, or a transceiver, broadcasting a shaped signal with the transmitter such that the shaped signal interacts with a boundary of a casing and a material and recording a result signal from the boundary with the receiver. The method may further comprise identifying a cut-off time to be applied to the result signal, transforming the result signal from a time domain to a frequency domain, selecting one or more modes sensitive to a bonding at the boundary between the casing and the material, computing a decay rate of the one or more modes that were selected based at least one or more decay curves, and converting the decay rate to a bonding log.