The present disclosure relates to borehole sonic logging and, more particularly to, improved reflection imaging of formation structures away from the wellbore. A method for borehole sonic reflection imaging may comprise: disposing a borehole sonic logging tool in a wellbore, wherein the borehole sonic logging tool comprises one or more transmitters and one or more receivers; emitting sound waves from the one or more transmitters; receiving sound waves at the one or more receivers to obtain borehole sonic data; separating up-going arrivals in the borehole sonic data from down-going arrivals in the borehole sonic data; generating a first reflection image based at least on the borehole sonic data; estimating a relative dip angle of a formation bed from the first reflection image; generating an updated velocity model based at least on the relative dip angle; and generating an updated reflection image based at least on the updated velocity model.

Disclosed are methods, systems, and computer-readable medium for a full seismic wavefield de-aliasing workflow. To achieve the de-aliasing, the workflow employs a four-dimension (4D) anti-leakage anti-aliasing regularization algorithm. The workflow involves application of successive de-aliasing steps while restricting computations only to the significant spatial dimensions. In areas of strong elastic property variation in the near-surface, the benefit of de-aliasing the full wavefield is both significant and demonstrable. In addition to achieving de-aliased sampling of the full wavefield, the workflow reduces the complexity of both the computational and geophysical aspects of the problem of de-aliasing full wavefields.

Systems and methods for generating seismic images of subterranean features including: receiving raw seismic data of a subterranean formation; selecting a portion of the raw seismic data; transforming the selected portion of the raw seismic data from a first domain to a second domain; generating soft constraint data corresponding to the selected portion of the raw seismic data; calculating at least one weight using the generated soft constraint data; generating a weighted transformed data set by applying at least one weight to the transformed selected portion of the raw seismic data; selecting at least one data point of the generated weighted transformed data set; and removing the selected at least one data point from the weighted transformed data set to generate revised seismic data.

Processes and systems for imaging a subterranean formation using continuously recorded seismic data obtained during a marine seismic geophysical survey of the subterranean formation are described herein. The processes and systems compute upgoing pressure data at stationary-receiver locations. and low-frequency noise attenuation processes and systems are applied to the upgoing pressure wavefield data to obtain low-frequency noise attenuated upgoing pressure wavefield data. An image of the subterranean formation, or data indicative thereof, may be generated using the low-frequency noise attenuated upgoing pressure wavefield data at stationary-receiver locations.

The present disclosure provides a vector denoising method for the multicomponent seismic data, including: obtaining a wave vector of the multicomponent seismic data; calculating a first mean wave vector for the multicomponent seismic data by applying a first moving window, performing a median filtering for the first mean wave vector to obtain a true modulus of the ground roll, subtracting the wave vector of the ground roll from the multicomponent seismic data to obtain a vector time-series; performing a mean filtering for the vector time-series by using a second moving window to obtain a second mean wave vector, performing a median filtering and performing a median the median filtering within the same receiving line for the second mean wave vector to suppress the wave vector of the random noise in the vector time-series, thereby obtaining a wave vector of a purified effective signal.

A method for wavefield separation of sonic data is provided. The method comprises estimating direct phases of waveforms of sonic data observed with two or more sensors by using cross-correlation of waveform traces at adjacent sensor locations, removing the direct phases from the observed waveforms, and extracting event signals from the waveforms after removing the direct phases.

Methods are described for separating the unknown contributions of two or more sources from a commonly acquired set of wavefield signals representing a wavefield where the sources are laterally located relatively close to each other and fire relatively close in time, and where the contributions from different sources are separated using different source encoding techniques in different parts of a frequency band of interest.

Waves from cement bond logging with a sonic logging-while-drilling tool (LWD-CBL) are often contaminated with tool waves and may yield biased CBL amplitudes. The disclosed LWD-CBL wave processing corrects the first echo amplitudes of LWD-CBL before calculating the BI. The LWD-CBL wave processing calculates a tool wave amplitude and a phase angle difference as the difference of the phases between the tool waves and casing waves. The tool waves are then used to correct the LWD-CBL casing wave amplitude and remove errors introduced from tool waves. In conjunction with the sets of operations described, the LWD-CBL wave processing also include array preprocessing operations. Array preprocessing may employ variation of bandpass filtering and frequency-wavenumber (F-K) filtering operations to suppress tool wave.

A simultaneous sources seismic acquisition method is described that introduces notch diversity to improve separating the unknown contributions of one or more sources from a commonly acquired set of wavefield signals while still allowing for optimal reconstruction properties in certain diamond-shaped regions. In particular, notch diversity is obtained by heteroscale encoding.

The present disclosure provides a vector denoising method for the multicomponent seismic data, including: obtaining a wave vector of the multicomponent seismic data; calculating a first mean wave vector for the multicomponent seismic data by applying a first moving window, performing a median filtering for the first mean wave vector to obtain a true modulus of the ground roll, subtracting the wave vector of the ground roll from the multicomponent seismic data to obtain a vector time-series; performing a mean filtering for the vector time-series by using a second moving window to obtain a second mean wave vector, performing a median filtering and performing a median the median filtering within the same receiving line for the second mean wave vector to supress the wave vector of the random noise in the vector time-series, thereby obtaining a wave vector of a purified effective signal.