A technique includes receiving data acquired by an acoustic measurement tool in a well, where the data represents multiple acoustic modes, including a first order formation flexural acoustic mode and a higher order formation flexural acoustic mode. The technique includes processing the data to identify the higher order formation flexural acoustic mode; and determining a shear slowness based at least in part on slowness values that are associated with the identified higher order formation flexural acoustic mode.

Embodiments of determining a vertically transverse isotropy (VTI) anisotropy along a horizontal section of a wellbore drilled into a formation are provided. One embodiment comprises determining elastic constants C11, C44, and C66 of the horizontal section and determining a vertical compressional slowness of the horizontal section corresponding to an elastic constant C33 of the horizontal section using a model with a condition. The model is built using second sonic log data and second density log data of the vertical wellbore. The condition is that the shear slowness (DTS) of the vertical wellbore is equal to the vertically polarized shear slowness (DTSV) of the horizontal section. The embodiment further comprises determining a VTI anisotropy along the horizontal section using the elastic constants C11, C44, C66, and C33 of the horizontal section.

A method of generating geophysical data using at least one source. The method may include the steps of generating a geophysical wavefield with a varying signature using at least one source, wherein the signature is varied in a periodic pattern.

Techniques for estimating and visually presenting formation slowness are disclosed herein. The techniques include receiving acoustic signal responses from adjacent formations at a plurality of depths in a borehole environment, mapping a distribution of the acoustic signal responses at each depth according to slowness and a frequency values, determining at least one confidence interval to define a coherence threshold for the distribution of the acoustic signal responses at each depth, generating a variable density log for each depth based on the distribution of acoustic signals responses that satisfy the confidence interval for one or more frequency ranges, determining a formation slowness value for each depth based on the variable density log for the each depth, and presenting a semblance map that includes a slowness axis, a depth axis, the formation slowness value for each depth, and at least a portion of the distribution of acoustic signal responses at each depth.

A method for processing seismic data may include receiving, via a processor, the seismic data acquired via a seismic survey. The seismic survey may include seismic sources that emit seismic wavefields at different locations. Each of the seismic sources may change a directivity pattern of a respective seismic wavefield based on a respective location of the respective seismic source. The seismic survey may also include seismic receivers that may receive the seismic data. The method may also include generating one or more basis functions that correspond to measurements of the seismic data, modelling a signal component of the seismic data as a sum of the one or more basis functions, and storing the signal component in a storage component. The signal component may be used to acquire an image of a subsurface region of the earth for identifying a feature in the subsurface region of the earth.

Methods and systems for displaying sonic logging data are described herein. The displayed data includes highly reliable quality control (QC) indicators that can be used to identify any need for a dispersion correction. The disclosed data-driven approach determines whether a dispersion curve is asymptotic to the true formation shear slowness by calculating a coherence of the slowness at frequency intervals of the dispersion curve to indicate the level of the velocity dispersion. This coherence indicator can then be plotted against the averaged slowness within the frequency interval to show how well the asymptotic slowness is approached. The coherence indicator can be projected onto a slowness log as a QC indicator. A calculated formation shear slowness can be overlaid upon the slowness log.

Systems and methods of performing a seismic survey are described. The system can receive seismic data in a first domain, and transform the seismic data into a tau-p domain. The system can identify a value on an envelope in the tau-p domain, select several values on the tau-p envelope using a threshold, and then generate a masking function. The system can combine the masking function with the tau-p transformed seismic data, and then perform an inverse tau-p transform on the combined seismic data. The system can adjust amplitudes in the inverse tau-p transformed combined seismic data, and identify one or more coherent events corresponding to subsea lithologic formations or hydrocarbon deposits.

A method for processing vertical seismic profiling (VSP) data is provided. The method includes receiving VSP data in response to seismic energy applied to the formation, processing a down-going portion of the VSP data associated with a down-going wave field, outputting a first set of estimation values based on processing the down-going portion of the VSP data, the first set of estimation values estimating at least one of slowness or velocity, processing an up-going portion of the VSP data associated with an up-going wave field, outputting a second set of estimation values based on processing the up-going portion of the VSP data, the second set of estimation values estimating at least one of slowness or velocity, and determining an estimation associated with the formation based on the first and second sets of estimation values.

A method and system for producing a Quasi-Static Stoneley Slowness log. The method for producing a Quasi-Static Stoneley Slowness log may comprise recording a pressure wave at a receiver; determining a slowness-frequency range with an information handling system from the pressure wave, processing a frequency-domain semblance, extracting a Stoneley Dispersion, minimizing a misfit between theoretical and the Stoneley Dispersion, and identifying Quasi-Static Stoneley slowness from the Stoneley Dispersion. The well measurement system for producing an Quasi-Static Stoneley Slowness log and shear slowness anisotropy may comprise a downhole tool, a vehicle, and an information handling system. Wherein the information handling system may be operable to record a pressure wave at a receiver, determine a slowness-frequency range with an information handling system from the pressure wave, process a frequency-domain semblance, extract a Stoneley Dispersion; minimize a misfit between theoretical and the Stoneley Dispersion; and identify Quasi-Static Stoneley slowness from the Stoneley Dispersion.

An acoustic logging system identifies hydrocarbon formation types by a real-time model-constrained mud wave slowness determination method using borehole guided waves. The system also combines data processing from different acoustic waveform processing techniques using an information sharing procedure, for example, using monopole source data and dipole source data, to further improve the processing results and to achieve more stable and reliable real-time shear slowness answers.