Abstract: Methods, systems and devices are disclosed for controlling self-induced acoustic interference. In one embodiment, a first piezoelectric transducer to which a first excitation signal is applied, generates back side acoustic waves that are transmitted from a back side of the first piezoelectric transducer into a backing material layer. A second piezoelectric transducer coupled to a back side of the backing material layer generates a first calibration response to the back side acoustic waves. An interference signal profile is generated based, at least in part, on the first calibration response and may be used to filter interference signal components and/or to generate a control signal to be applied to the second piezoelectric transducer during measurement cycles.

Abstract: Methods, systems and devices are disclosed for controlling self-induced acoustic interference. In one embodiment, a first piezoelectric transducer to which a first excitation signal is applied, generates back side acoustic waves that are transmitted from a back side of the first piezoelectric transducer into a backing material layer. A second piezoelectric transducer coupled to a back side of the backing material layer generates a first calibration response to the back side acoustic waves. An interference signal profile is generated based, at least in part, on the first calibration response and may be used to filter interference signal components and/or to generate a control signal to be applied to the second piezoelectric transducer during measurement cycles.

Abstract: An apparatus includes a mechanical wave source; a set of mechanical wave sensors in a borehole to provide subsurface wave measurements based on formation waves from the mechanical wave source, and a processor. The apparatus also includes a machine-readable medium having program code to acquire the subsurface wave measurements, select a first set of tool wave measurements based on the subsurface wave measurements, and generate a set of filtered subsurface wave measurements by filtering the subsurface wave measurements based on the first set of tool wave measurements. The program code also includes instructions to generate a time-domain semblance map based on the set of filtered subsurface wave measurements, wherein the time-domain semblance map includes an initial set of compression wave peaks, determine a selected qualified compression wave peak based on a semblance value in the time-domain semblance map, and determine a compression wave slowness based on the selected qualified compression wave peak.

Abstract: Disclosed is a system and method for calculating a formation shear-wave slowness. The system includes a borehole sonic logging tool and an information handling system. The borehole sonic logging tool may comprise a transmitter comprising one or more elements disposed at one or more radial distances from an axis of the borehole sonic logging tool and the transmitter is configured to transmit a first mode into a borehole. The sonic logging tool may further include one or more receivers disposed at a second radial distance from the axis of the borehole sonic logging tool and are configured to detect a second mode that one or more lobes than is a higher order than the first mode. A method may comprise broadcasting the first mode into the borehole, recording the second mode from the borehole with the one or more receivers, and calculating the formation shear-wave slowness from the second mode.

Abstract: To generate dispersion curves for acoustic waves in a radially layered system, a matrix M containing solutions to the wave equation subject to the boundary conditions of the system is constructed. The reciprocal condition number (RCN) of the matrix M is determined as a function of acoustic wave frequency and slowness. The local minima of the RCN in the frequency-slowness plane produces the dispersion curves corresponding to allowable acoustic modes in the system. A sensitivity analysis which identifies the dispersion curves dependent on a selected parameter. The dispersion curves independent of the perturbed parameters are eliminated by perturbing the modeling parameters and generating the RCN of the perturbed matrix M and then subtracting the RCN values of the unperturbed matrix M, leaving the dispersion curves that exhibit dependence on the selected parameter.

Abstract: A logging-while-drilling (LWD) tool for use within a formation. The LWD tool may include a transmitter, a receiver, and an acoustic isolator. The transmitter may be operable to transmit an acoustic signal into the formation. The receiver may be operable to receive an acoustic response from the formation. The acoustic isolator may be positioned longitudinally between the transmitter and the receiver to reduce a transfer of acoustic energy between the transmitter and the receiver through the LWD tool. The acoustic isolator may include annular chambers formed in a body of the acoustic isolator and positioned along a longitudinal axis of the acoustic isolator.

Abstract: Acoustic waves are obtained from an acoustic logging tool within a borehole passing through a formation. Signal properties in a time domain, frequency domain, or both are determined based on the obtained acoustic waves. A machine learning analysis is used to determine formation slowness based on the determined signal properties and a downhole operational parameter is adjusted based on the determined formation slowness.

Abstract: A logging-while-drilling (LWD) tool for use within a formation. The LWD tool may include a transmitter, a receiver, and an acoustic isolator. The transmitter may be operable to transmit an acoustic signal into the formation. The receiver may be operable to receive an acoustic response from the formation. The acoustic isolator may be positioned longitudinally between the transmitter and the receiver to reduce a transfer of acoustic energy between the transmitter and the receiver through the LWD tool. The acoustic isolator may include annular chambers formed in a body of the acoustic isolator and positioned along a longitudinal axis of the acoustic isolator.

Abstract: To generate dispersion curves for acoustic waves in a radially layered system, a matrix M containing solutions to the wave equation subject to the boundary conditions of the system is constructed. The reciprocal condition number (RCN) of the matrix M is determined as a function of acoustic wave frequency and slowness. The local minima of the RCN in the frequency-slowness plane produces the dispersion curves corresponding to allowable acoustic modes in the system. A sensitivity analysis which identifies the dispersion curves dependent on a selected parameter. The dispersion curves independent of the perturbed parameters are eliminated by perturbing the modeling parameters and generating the RCN of the perturbed matrix M and then subtracting the RCN values of the unperturbed matrix M, leaving the dispersion curves that exhibit dependence on the selected parameter.

Abstract: Acoustic waves are obtained from an acoustic logging tool within a borehole passing through a formation. Signal properties in a time domain, frequency domain, or both are determined based on the obtained acoustic waves. A machine learning analysis is used to determine formation slowness based on the determined signal properties and a downhole operational parameter is adjusted based on the determined formation slowness.

Abstract: Disclosed is a system and method for calculating a formation shear-wave slowness. The system includes a borehole sonic logging tool and an information handling system. The borehole sonic logging tool may comprise a transmitter comprising one or more elements disposed at one or more radial distances from an axis of the borehole sonic logging tool and the transmitter is configured to transmit a first mode into a borehole. The sonic logging tool may further include one or more receivers disposed at a second radial distance from the axis of the borehole sonic logging tool and are configured to detect a second mode that one or more lobes than is a higher order than the first mode. A method may comprise broadcasting the first mode into the borehole, recording the second mode from the borehole with the one or more receivers, and calculating the formation shear-wave slowness from the second mode.

Abstract: A method may comprise recording a first reflected waveform with a first transducer to form a first data set from a first excitation, recording a second reflected waveform with a second transducer to form a second data set from a second excitation, estimating a first sensitivity correction factor for the first data set, applying the first sensitivity correction factor to at least a portion of the first data set to form a first sensitivity corrected data set. The method may further comprise estimating a second sensitivity correction factor for the second data set, applying the second sensitivity correction factor to at least a portion of the second data set to form a second sensitivity corrected data set, stacking the first sensitivity corrected data set amplitudes and forming a first image, stacking the second sensitivity corrected data set amplitudes and forming a second image, and comparing the images.

Abstract: An apparatus includes a mechanical wave source; a set of mechanical wave sensors in a borehole to provide subsurface wave measurements based on formation waves from the mechanical wave source, and a processor. The apparatus also includes a machine-readable medium having program code to acquire the subsurface wave measurements, select a first set of tool wave measurements based on the subsurface wave measurements, and generate a set of filtered subsurface wave measurements by filtering the subsurface wave measurements based on the first set of tool wave measurements. The program code also includes instructions to generate a time-domain semblance map based on the set of filtered subsurface wave measurements, wherein the time-domain semblance map includes an initial set of compression wave peaks, determine a selected qualified compression wave peak based on a semblance value in the time-domain semblance map, and determine a compression wave slowness based on the selected qualified compression wave peak.

Abstract: Methods, systems and devices are disclosed for controlling self-induced acoustic interference. In one embodiment, a first piezoelectric transducer to which a first excitation signal is applied, generates back side acoustic waves that are transmitted from a back side of the first piezoelectric transducer into a backing material layer. A second piezoelectric transducer coupled to a back side of the backing material layer generates a first calibration response to the back side acoustic waves. An interference signal profile is generated based, at least in part, on the first calibration response and may be used to filter interference signal components and/or to generate a control signal to be applied to the second piezoelectric transducer during measurement cycles.

Abstract: A method and system for reducing transducer ringing. The method may comprise identifying a first set of waveforms and a second set of waveforms from recorded waveforms taken by a transducer, estimating an invariant component for each waveform in the first set of waveforms, and subtracting the invariant component from the second set of waveforms. The system may comprise a downhole tool. The downhole tool may comprise at least one transducer and wherein the at least one transducer is configured to emit an excitation and record a plurality of waveforms. The system may further comprise an information handling system configured to identify a first set of waveforms and a second set of waveforms from the plurality of waveforms from the at least one transducer, estimate an invariant component for each waveform in the first set of waveforms, and subtract the invariant component from the second set of waveforms.

Abstract: Disclosed herein are implementations of various technologies for a method for seismic data processing. The method may receive seismic data for a region of interest. The seismic data may be acquired in a seismic survey. The method may determine an exclusion criterion. The exclusion criterion may provide rules for selecting shot points in the acquired seismic data. The method may determine sparse seismic data using statistical sampling based on the exclusion criterion and the acquired seismic data. The method may determine simulated seismic data based on the earth model and shot points corresponding to the sparse seismic data. The method may determine an objective function that represents a mismatch between the sparse seismic data and the simulated seismic data. The method may update the earth model using the objective function.

Abstract: A method and system for reducing transducer ringing. The method may comprise identifying a first set of waveforms and a second set of waveforms from recorded waveforms taken by a transducer, estimating an invariant component for each waveform in the first set of waveforms, and subtracting the invariant component from the second set of waveforms. The system may comprise a downhole tool. The downhole tool may comprise at least one transducer and wherein the at least one transducer is configured to emit an excitation and record a plurality of waveforms. The system may further comprise an information handling system configured to identify a first set of waveforms and a second set of waveforms from the plurality of waveforms from the at least one transducer, estimate an invariant component for each waveform in the first set of waveforms, and subtract the invariant component from the second set of waveforms.

Abstract: A method may comprise recording a first reflected waveform with a first transducer to form a first data set from a first excitation, recording a second reflected waveform with a second transducer to form a second data set from a second excitation, estimating a first sensitivity correction factor for the first data set, applying the first sensitivity correction factor to at least a portion of the first data set to form a first sensitivity corrected data set. The method may further comprise estimating a second sensitivity correction factor for the second data set, applying the second sensitivity correction factor to at least a portion of the second data set to form a second sensitivity corrected data set, stacking the first sensitivity corrected data set amplitudes and forming a first image, stacking the second sensitivity corrected data set amplitudes and forming a second image, and comparing the images.

Abstract: A predetermined condition in a fluid-filled wellbore system can be detected by generating at least one sound in the wellbore system in response to the condition, such that a detectable change is created in some characteristic of the emitted sound, and detecting the at least one sound and the change, the detection being indicative that the predetermined condition has occurred. Equipment for facilitating detection of the condition can include a trigger operable in response to the condition; a generator operable to emit sound in the borehole and to create a detectable change in some characteristic of the emitted sound in response to the trigger; and at least one sensor operable to monitor the sound and detect the change, the detection being indicative that the predetermined condition has occurred. It is also possible to estimate a value of a property of a fluid-filled wellbore system.

Abstract: Described herein are implementations of various technologies for a method for seismic data processing. The method may receive seismic data for a region of interest. The seismic data may be acquired in a seismic survey. The method may determine a seismic image based on the acquired seismic data and an earth model of the region of interest. The method may determine simulated seismic data based on the earth model. The method may determine an objective function that represents a mismatch between the acquired seismic data and the simulated seismic data. The method may determine a diffusion tensor using geological information from the seismic image. The method may update the earth model using the diffusion tensor with the objective function.