Various implementations directed to quality control and preconditioning of seismic data are provided. In one implementation, a method may include receiving particle motion data from particle motion sensors disposed on seismic streamers. The method may also include performing quality control (QC) processing on the particle motion data. The method may further include performing preconditioning processing on the QC-processed particle motion data. The method may additionally include attenuating noise in the preconditioning-processed particle motion data.

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.

Implementations described and claimed herein provide systems and methods for isolation detection. In one implementation, an axial acoustic signal is obtained. The axial acoustic signal is captured using an axial sensor deployed in a structure in a subterranean surface. The axial acoustic signal is separated into a first wave region and a second wave region by applying velocity filtering. An axial symmetry of a portion of the structure is determined based on at least one of the first wave region or the second wave region.

Implementations described and claimed herein provide systems and methods for isolation detection. In one implementation, recorded data is obtained. The recorded data includes radial acoustic waves transmitted and received using a radial sensor of an acoustic logging tool deployed in a wellbore. Clockwise waves are separated from counterclockwise waves by converting the recorded data from a time domain to a frequency domain. The clockwise waves are shifted into shifted clockwise waves, and the counterclockwise waves are shifted into a shifted counterclockwise waves. A forward wave is generated by combining the shifted clockwise waves, and a reflected wave is generated by combining the shifted counterclockwise waves. One or more isolation regions are identified in the wellbore using the forward wave and the reflected wave.

A surface-consistent refraction analysis method to automatically derive near surface corrections for seismic data processing. The method uses concepts from surface-consistent analysis applied to refracted arrivals. The method includes the use of CMP-offset-azimuth binning, evaluation of mean travel time and standard deviation for each bin, rejection of anomalous first break (FB) picks, derivation of CMP-based travel time-offset functions, conversion to velocity-depth functions, evaluation of long wavelength statics and calculation of surface-consistent residual statics through waveform cross-correlation. Residual time lags are evaluated in multiple CMP-offset-azimuth bins by similarity analysis with a pilot trace for all the other traces in the gather where the correlation window is centered at the refracted arrival. The similarity analysis may take the form of computerized cross-correlation, or other criteria such as semblance. The residuals are then used to build a system of linear equations that is simultaneously inverted for surface-consistent shot and receiver time shift corrections plus a possible subsurface residual term. All the steps are completely automated and require a fraction of the time needed for conventional near surface analysis.

A method of enhancing seismic images includes receiving a seismic gather. The seismic gather includes a plurality of seismic traces. A feature trace is generated based on the plurality of seismic traces in the seismic gather. For each of the plurality of seismic traces in the seismic gather, a correlation trace is generated based on that seismic trace and the feature trace, the correlation trace is modified using an activation function, and an enhanced trace is generated by multiplying that seismic trace with the modified correlation trace.

A surface-consistent refraction analysis method to automatically derive near surface corrections for seismic data processing. The method uses concepts from surface-consistent analysis applied to refracted arrivals. The method includes the use of CMP-offset-azimuth binning, evaluation of mean travel time and standard deviation for each bin, rejection of anomalous first break (FB) picks, derivation of CMP-based travel time-offset functions, conversion to velocity-depth functions, evaluation of long wavelength statics and calculation of surface-consistent residual statics through waveform cross-correlation. Residual time lags are evaluated in multiple CMP-offset-azimuth bins by similarity analysis with a pilot trace for all the other traces in the gather where the correlation window is centered at the refracted arrival. The similarity analysis may take the form of computerized cross-correlation, or other criteria such as semblance. The residuals are then used to build a system of linear equations that is simultaneously inverted for surface-consistent shot and receiver time shift corrections plus a possible subsurface residual term. All the steps are completely automated and require a fraction of the time needed for conventional near surface analysis.

A surface-consistent refraction analysis method to automatically derive near surface corrections for seismic data processing. The method uses concepts from surface-consistent analysis applied to refracted arrivals. The method includes the use of CMP-offset-azimuth binning, evaluation of mean travel time and standard deviation for each bin, rejection of anomalous first break (FB) picks, derivation of CMP-based travel time-offset functions, conversion to velocity-depth functions, evaluation of long wavelength statics and calculation of surface-consistent residual statics through waveform cross-correlation. Residual time lags are evaluated in multiple CMP-offset-azimuth bins by similarity analysis with a pilot trace for all the other traces in the gather where the correlation window is centered at the refracted arrival. The similarity analysis may take the form of computerized cross-correlation, or other criteria such as semblance. The residuals are then used to build a system of linear equations that is simultaneously inverted for surface-consistent shot and receiver time shift corrections plus a possible subsurface residual term. All the steps are completely automated and require a fraction of the time needed for conventional near surface analysis.

Methods and systems of generating seismic images from primaries and multiples are described. Methods separate pressure data into up-going pressure data and down-going pressure data from pressure data and vertical velocity data. Irregularly spaced receiver coordinates of the down-going and up-going pressure data are regularized to grid points of a migration grid and interpolation is used to fill in down-going and up-going pressure data at grid points of the migration grid. A seismic image is calculated at grid points of the migration grid based on the interpolated and regularized down-going pressure data and the interpolated and regularized up-going pressure data. The seismic images are high-resolution, have lower signal-to-noise ratio than seismic images generated by other methods, and have reduced acquisition artifacts and crosstalk effects.

Methods for processing seismic data acquired with non-impulsive moving sources are provided. Some methods remove cross-talk noise from the seismic data using emitted signal data and an underground formation's response estimate, which may be iteratively enhanced. Some methods perform resampling before a spatial or a spatio-temporal inversion. Some methods compensate for source's motion during the inversion, and/or are usable for multiple independently moving sources.