A method may include obtaining seismic data regarding a geological region of interest. The seismic data may include various pre-processed gathers. The method may further include obtaining a machine-learning model that is pre-trained to predict migrated seismic data. The method may further include selecting various training gathers based on a portion of the pre-processed gathers, a migration function, and a velocity model. The method may further include generating a trained model using the training gathers, the machine-learning model, and a machine-learning algorithm. The method may further include generating a seismic image of the geological region of interest using the trained model and a remaining portion of the seismic data.

A method is provided of inspecting a nested multi-layer structure including a first and second electrically conductive layer and a third layer disposed behind the second conductive layer. The method includes deploying a sensor device including an electromagnetic acoustic transducer to a borehole location proximate to the structure, generating a drive signal including a plurality of frequencies, applying an electrical current signal to the sensor device based on the drive signal and inducing currents in the first conductive layer that induce currents generating acoustic signals having the plurality of frequencies, detecting a first set of resonant frequencies based on received electromagnetic signals, detecting a second set of resonant frequencies based on received acoustic signals, estimating a property of the first and/or the second conductive layer based on the first set of resonant frequencies, and estimating a property of the third layer based on the second set of resonant frequencies.

A method is provided of inspecting a nested multi-layer structure including a first and second electrically conductive layer and a third layer disposed behind the second conductive layer. The method includes deploying a sensor device including an electromagnetic acoustic transducer to a borehole location proximate to the structure, generating a drive signal including a plurality of frequencies, applying an electrical current signal to the sensor device based on the drive signal and inducing currents in the first conductive layer that induce currents generating acoustic signals having the plurality of frequencies, detecting a first set of resonant frequencies based on received electromagnetic signals, detecting a second set of resonant frequencies based on received acoustic signals, estimating a property of the first and/or the second conductive layer based on the first set of resonant frequencies, and estimating a property of the third layer based on the second set of resonant frequencies.

Methods of mapping a subterranean formation using imploding particles are described. In some cases, the particles contain a material that generated a gas which passes through a water-insoluble coating to create a void within the particle. In some aspects, the implosive particles have a coating that dissolves in the subterranean formation.

Methods of mapping a subterranean formation using imploding particles are described. In some cases, the particles contain a material that generated a gas which passes through a water-insoluble coating to create a void within the particle. In some aspects, the implosive particles have a coating that dissolves in the subterranean formation.

The disclosed embodiments include quadrupole transmitters and methods to determine wave velocities of a downhole formation. In some embodiments, the quadrupole transmitter has a first piezoelectric ring and a second piezoelectric ring that alternatively contracts and expands in opposite radial directions relative to the first piezoelectric ring in response to being simultaneously excited with the first piezoelectric ring. The quadrupole transmitter also includes a covering sleeve surrounding exterior surfaces of the two piezoelectric rings. The quadrupole transmitter further includes a windowed sleeve surrounding the two piezoelectric rings and having a first portion and a second portion adjacent to the first portion. The first portion and the second portion are formed from multiple window sections and adjacent covered sections that are positioned around different sections of the piezoelectric rings to allow transmission of quadrupole acoustic signals when the piezoelectric rings are simultaneously excited.

A system for determining a fingerprint of a structure is provided. The system includes a plurality of granules inserted in a structure having a plurality of fissures, fractures, and cracks (collectively apertures), each granule comprising a membrane, and at least one bubble of compressed gas formed in the membrane, the membrane selectively dissolving in presence of a predetermined fluid and thereby selectively bursting the at least one bubble, thereby generating a concussing vibration, at least at least i) three detection devices for two-dimensional mapping or ii) four detection devices for three-dimensional mapping placed proximate to the structure according to a predetermined placement schedule, and a computing device comprising a processor configured to receive data from the at least three or four detection devices and to determine location of the at least one bubble of each of the plurality of the granules at the time of bursting by triangulating the concussive vibration in order to determine location of the at least one bubble.

A system for determining a fingerprint of a structure is provided. The system includes a plurality of granules inserted in a structure having a plurality of fissures, fractures, and cracks (collectively apertures), each granule comprising a membrane, and at least one bubble of compressed gas formed in the membrane, the membrane selectively dissolving in presence of a predetermined fluid and thereby selectively bursting the at least one bubble, thereby generating a concussing vibration, at least at least i) three detection devices for two-dimensional mapping or ii) four detection devices for three-dimensional mapping placed proximate to the structure according to a predetermined placement schedule, and a computing device comprising a processor configured to receive data from the at least three or four detection devices and to determine location of the at least one bubble of each of the plurality of the granules at the time of bursting by triangulating the concussive vibration in order to determine location of the at least one bubble.

Systems and methods of near surface imaging and hazard detection with increased receiver spacing are provided. The system includes: a first string of one or more acoustic sources, a second string of one or more acoustic sources opposite the first string, a first one or more hydrophones mounted within a predetermined distance of the first string, and a second one or more hydrophones mounted within the predetermined distance of the second string. The first one or more hydrophones records an acoustic shot generated from the first string. The second one or more hydrophones records the acoustic shot and acoustic reflections corresponding to the acoustic shot. The system generates an image from the recorded acoustic shot and the acoustic reflections.

A well tool can be used in a wellbore that can measure characteristics of an object in the wellbore. The well tool includes an ultrasonic transducer for generating an ultrasonic wave in a medium of the wellbore. The ultrasonic transducer includes a front layer, a rear layer, backing material coupled to the rear layer, and piezoelectric material coupled to the front layer and to the backing material. The rear layer can improve signal-to-noise ratio of the transducer in applications such as imaging and caliper applications.