Abstract: Methods and systems are disclosed for determining a material property transition within a wellbore. In some embodiments, a method includes determining a material transition profile for each of a plurality of test points within a linear measurement path including, for each test point, determining an acoustic response for a first location within the linear measurement path, and determining an acoustic response for a second location within the linear measurement path. The test point is between the first and second locations. The method further includes generating a material transition profile for the test point based, at least in part, on a difference between the acoustic response at the first location and the acoustic response at the second location.

Abstract: A method and system for locating a reflector in a formation. The method may comprise broadcasting a sonic waveform as a shear formation body wave or a compressional formation body wave into the formation, recording a reflected wave from a reflector with the one or more receivers as dipole data by the dipole receiver and quadrupole data by the quadrupole receiver, and processing the dipole data and the quadrupole data with an information handling system to determine a location of the reflector from the borehole sonic logging tool. The system may comprise a borehole sonic logging tool and an information handling system. The borehole sonic logging tool may comprise one or more transmitters configured to transmit a sonic waveform into a formation and one or more receivers configured to record a reflected wave as a dipole receiver for dipole data and a quadrupole receiver for quadrupole data.

Abstract: Methods, systems, and program products are disclosed for implementing acoustic logging and determining wellbore material characteristics. In some embodiments, a method may include determining a polar differential signal for each of one or more pairs of azimuthally offset acoustic measurements within a wellbore. A reference azimuth is identified based, at least in part, on comparing the polar differential signals to a modeled bonding differential signal within a target response window. The method further includes determining differences between an acoustic measurement at the reference azimuth and acoustic measurements at one or more other azimuths and determining a wellbore material condition based, at least in part, on the determined differences.

Abstract: Logging of data by a downhole tool disposed in a borehole may be affected by tool wave effects. The tool waves appear in the first echo of casing wave arrivals and the amplitudes may be much larger than casing wave arrivals. The estimates of casing wave amplitude are biased due to these tool wave arrivals when using conventional cement-bond logging (CBL) processing. An automated adaptive inversion-based array processing for CBL evaluation using a downhole tool provides an improvement in the calculation of a bonding index.

Abstract: A method for enhanced dispersion analysis begins with obtaining a plurality of measured waveforms, for example from two or more receivers of an acoustic logging tool placed in a borehole. The measured waveforms are divided into common gathers, and waveforms of each common gather are enhanced. The enhancement begins by calculating a travel time curve for a selected target mode of the common gather waveforms. Using the travel time curve, waveforms of the selected target mode are aligned to have zero apparent slowness. The aligned waveforms are filtered to suppress non-target mode waves. The aligned waveforms are then enhanced, and used to generate an enhanced dispersion curve of the selected target mode.

Abstract: Methods to estimate formation slowness from multi-borehole modes and multi-mode dispersion estimation systems are presented. The method includes obtaining waveform data of a plurality of waves traversing through a downhole formation, wherein each wave of the plurality of waves has a different threshold cutoff frequency, and performing a multimode dispersion analysis of the waveform data to generate a semblance map of the wave comprising the plurality of waves. The method also includes obtaining a slowness dispersion of a wave of the plurality of waves, and determining a formation type of the wave based on one or more properties of the plurality of waves. The method further includes determining an initial body wave slowness estimate of the wave, generating a modeling of the wave, and reducing a mismatch between the modeling of the wave and the slowness dispersion of the wave to improve the modeling of the wave.

Abstract: Disclosed are systems and methods for processing acoustic logging information with automatic dispersion matching. The method comprises obtaining, from an acoustic logging tool, acoustic waveforms from within a borehole, applying dispersion analysis to the acoustic data to extract a slowness-frequency response, calculating a slowness density log of the slowness-frequency response, obtaining an initial shear slowness estimate based on the slowness density, generating a dispersion model comprising model parameters, and performing a dispersion response auto match inversion to minimize the difference between the slowness-frequency response and the dispersion model in order to obtain a final shear slowness estimate.

Abstract: A method for determining mud properties may comprise taking multi-frequency measurement data with a downhole tool, selecting an injector electrode from the one or more injector electrodes for the multi-frequency measurement data, selecting data from the multi-frequency measurement data with low resistivity or a large standoff, creating a forward model based at least partially on the selected data by making initial guesses of model parameters for one or more mud properties, performing a cost function minimization with the forward model, identifying from the cost function minimization if a misfit is above or below a threshold, and identifying the one or more mud properties based at least in part on the cost function minimization. A system may comprise a downhole tool including a mandrel, one or more arms, one or more pads, and one or more injector electrodes. The system may further include an information handling system.

Abstract: Techniques for calculating and visually presenting multiple acoustic modes that have different formation slowness are disclosed herein. The techniques include methods for receiving time-domain waveforms from adjacent formations in a borehole, processing each of the time-domain waveforms to generate frequency-domain spectrums, selecting frequency and slowness values, and predicting travel time of a mode associated with the slowness value. In some aspects, the method further includes steps for calculating a semblance difference of the frequency-domain spectrums based on the frequency value, the slowness value and the predicted travel time. Systems and computer-readable media are also provided.

Abstract: Apparatus, methods, and systems for determining body wave slowness values for a target formation zone. A method includes selecting a target axial resolution based on the size of a receiver array, obtaining a plurality of waveform data sets corresponding to a target formation zone and each acquired at a different shot position, reconstructing the plurality of waveform data sets to generate a plurality of subarray data sets corresponding to the target formation zone, determining a slowness value for each subarray data set and determining a slowness versus offset value for each subarray data set. The method may also include generating a borehole model having at least one alteration formation zone and a virgin formation zone and generating a slowness versus offset model based at least in part on the borehole model. The method may also include determining a radial depth of the alteration formation zone.

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 portion of an anisotropy formation through which a wellbore is formed can be identified. An estimate of an elastic anisotropy parameter for the portion can be adjusted based on a first quality control analysis using the elastic anisotropy parameter for the portion. The first signal representing the elastic anisotropy parameter for the portion. The estimate of the elastic anisotropy parameter for the portion can be adjusted based on a second quality control analysis using estimates for the elastic anisotropy parameters for two or more portions of the anisotropy formation.

Abstract: Disclosed are systems and methods for high precision acoustic logging processing for compressional and shear slowness. The method comprises measuring, by a sonic logging tool, sonic data associated with a formation within a borehole, attempting a detection of a first arrival within the sonic data determining whether the attempted detection of the first arrival is accurate, and in response to an accurate detection of the first arrival determining a travel time of the first arrival, generating a coherence map including the first arrival, and determining, based on the coherence map, a characteristic of the formation.

Abstract: Reducing casing wave effects on sonic logging data by positioning two or more receivers in a borehole in a subsurface formation; receiving, at two or more receivers in a borehole in a subsurface formation, a first signal associated with a first acoustic signal originating from a first transmitter position; receiving, at the two or more receivers, a second signal associated with a second acoustic signal originating from a second transmitter position; creating a dataset based on the first signal and the second signal; identifying casing wave signals in the dataset based at least in part on the second signal; calculating inverse-phase casing wave signals based at least in part on the casing wave signals and the second signal; and reducing effects of the casing wave signals on the dataset using the inverse-phase casing wave signals.

Abstract: The present disclosure relates to determining a location of a noise source where the location includes azimuth information and determining cement-bond integrity. A downhole tool disposed in a borehole may comprise one or more receivers (such as a monopole receiver and any one or more of one or more multi-pole receivers) and in certain embodiments one or more transmitters that fire one or more shots may provide azimuthal estimate of the location of a noise source, a location of a leak in one or more layers of a casing, cement-bond integrity any combination thereof based, at least in part, on one or more measurements or data for received signals at any one or more receivers. Accurate and efficient identification of a leak or integrity of a cement-bond reduces overall inefficiencies and costs associated with a downhole operation.

Abstract: Logging of data by a downhole tool disposed in a borehole may be affected by tool wave effects. The tool waves appear in the first echo of casing wave arrivals and the amplitudes may be much larger than casing wave arrivals. The estimates of casing wave amplitude are biased due to these tool wave arrivals when using conventional cement-bond logging (CBL) processing. An automated adaptive inversion-based array processing for CBL evaluation using a downhole tool provides an improvement in the calculation of a bonding index.

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 tool for performing well logging activities in a geologic formation has one or more transmitters, one or more receivers, and a tool wave propagating factor which differs from a formation wave propagating factor. The one or more transmitters excite a tool wave and formation wave. The tool wave is reduced by the one or more transmitters transmitting an acoustic wave which causes the tool wave to be reduced. Additionally, or alternatively, the tool wave is reduced by generating an inverse estimate of the tool wave based on waveform data associated with the tool wave and formation wave received by each of the one or more receivers.

Abstract: Systems and methods are provided for determining a formation body wave slowness from an acoustic wave. Waveform data is determined by logging tool measuring the acoustic wave. Wave features are determined from the waveform data and a model is applied to the wave features to determine data-driven scale factors The data-driven scale factors can be used to determine a body wave slowness within a surrounding borehole environment and the body wave slowness can be used to determine formation characteristics of the borehole environment.

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.