Systems and methods may be used to process distributed acoustic sensing (DAS) data at oil and gas well sites to generate processed seismic data having metadata superimposed thereon, and then stream the combined processed seismic data and metadata to an off-site data processing center for further customized data processing. For example, a method may include receiving raw seismic data from a plurality of sensors disposed in a borehole extending into a subterranean formation from the oil and gas well site, processing the raw seismic data to generate a plurality of processed seismic data waveforms and metadata associated with the plurality of processed seismic data waveforms, combining the plurality of processed seismic data waveforms and the metadata associated with the plurality of processed seismic data waveforms to generate an output file, and streaming the output file to an off-site data processing center that is located remotely from the oil and gas well site.

The disclosed method includes receiving resulting signals emanating from a subterranean formation, wherein the resulting signals are caused by signals emitted from seismic sources. The method further includes dividing the resulting signals into a plurality of sub-samples. The method includes determining a frequency content of one or more of the sub-samples and assigning a weight to or more components of the frequency content of the sub-sample to produce a weighted frequency content of the sub-sample, wherein the assigned weight is based, at least in part, on an estimate of the amount of noise present in the frequency content of the sub-sample. The method further includes combining the weighted frequency contents of the sub-samples to produce a weighted sample. The method further includes determining one or more properties of the subsurface formation based, at least in part, on the weighted sample.

Methods, systems, and computer-readable medium to perform operations including: generating a first time-frequency spectrum of a first seismic trace from an original seismic dataset; generating a second time-frequency spectrum of a second seismic trace from an enhanced seismic dataset, where the second seismic trace corresponds to the first seismic trace; and re-combining an amplitude spectrum of the first time-frequency spectrum and a phase spectrum of the second time-frequency spectrum to generate a third time-frequency spectrum of an output trace that corresponds to the first and second seismic traces.

This disclosure is directed to systems and methods for stacking seismic data. The methods receive seismic data collected from a survey of a subterranean formation. A gather of seismic data may have flattened reflection events obtained as a result of normal moveout (NMO) corrections or pre-stack migration. Alternatively, the gather may be an unmigrated gather with non-horizontal reflection events. A smoothed-amplitude gather is generated from the gather. Traces of the gather are stacked to generate a trace with significantly reduced noise using corresponding smoothed amplitudes of the smoothed-amplitude gather as weights.

Disclosed is a method of, and computer program and apparatus for, identifying reflected signals, subsequent to their reflection within a medium. The method comprises obtaining return signals (100), resulting from measurements being performed over a measurement period. The measurement period comprises sub-periods, the return signals comprising reflected signals and noise. The plurality of return signals are partitioned into plural sets (220) of equal cardinality or as equal as possible such that their cardinality differs by no more than one. A stacked correlation value is determined (130) for the return signals by determining the mean of the return signals across the plural sets (230) and determining a correlation value of the plural sets over each of the time sub-periods (240). Peaks in the variation of the stacked correlation value over time can then be identified and each of the peaks in the variation of the stacked correlation value over time can be attributed to a reflected signal.

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 coventional near surface analysis.

Disclosed is a method for determining seismic event data from indications of seismic noise, the method including receiving seismic trace data from a plurality of locations, and providing a virtual trace value (E.sub.Rvirtual) as seismic event data for a virtual trace location from the seismic trace data. A system and computer program product for determining seismic event data is also disclosed.

Disclosed systems and methods provide enhanced seismic images through the use of partial image stacking weights that are based on the resemblance between the local partial image and a reference image. At least some method embodiments include obtaining partial images of a survey region and stacking the partial images to produce a reference image. The partial images are then recombined to form an enhanced image, wherein the recombining includes: measuring at each point the reference image's similitude with each of the partial images; and determining at each point an enhanced image value from a weighted combination of corresponding values in the partial images, the weighted combination using weights derived from the reference images' similitude at that point to each partial image.

The present disclosure provides a prestack separating method for a seismic wave, including: receiving P-wave, S1-wave and S2-wave of the seismic wave, wherein the P-wave, S1-wave and S2-wave are reflected from different points; projecting the P-wave, S1-wave and S2-wave into a Z-R-T coordinate system, so as to generate a projection matrix, wherein Z is a vertical component, R is a component of a source-to-receiver azimuth and T is a component orthogonal to the R component; forming vectors of the P-wave, S1-wave and S2-wave as a composite vector; transforming the composite vector to an anisotropic wave vector matrix according to base vectors on the vector directions of the P-wave, S1-wave and S2-wave; and performing a rotation transformation of an affine coordinate system on the anisotropic wave vector matrix to generate a wave separation matrix, thereby solving a problem of error prediction result of fracture parameters caused by the mode leakage phenomenon.

Embodiments of super-virtual borehole sonic interferometry include machines, systems, and methods that can increase the signal-to-noise ratio of sonic log waveforms. Embodiments include performing a common shot gather and recording traces with a sonic tool, repositioning the tool and performing another common-shot gather; cross-correlating each trace with neighboring corresponding traces for each common shot gather, which leads to creating the virtual trace response due to a redatumed virtual source; stacking the common virtual traces with common ray paths for different common shot gathers; convolving the virtual traces with an actual trace that travels from the source through the virtual source to a receiver on the tool; and stacking the traces having common ray paths. The resulting waveforms can have a signal-to-noise ratio significantly greater than the signal-to-noise ratio of the original waveforms, due to the two stacking operations following each redatuming step.