A method is described for removing the surface ghost from and/or separating wave field data and/or for estimating redatuming operators of the wave field data by effective use of a transform that that relies on the non-uniform distribution of distances with respect to a reference surface or of tuned-source radiation directions of sources and or the non-uniform distribution of receivers with respect to a reference surface to partition or map the wave field from at least two different cones in the transformed domain and using the contribution of sources and or receivers inside at least one of the at least two different cones to estimate a first wave field of interest, a second separated or ghost wave field and/or redatuming operator.

A method for processing sonic data acquired with a downhole sonic tool is provided. The method comprises detecting coherent noise based on a plurality of waveforms obtained from one or more receivers issued by one or more transmitters. The plurality of waveforms correspond to propagating acoustic waves in a formation. In addition, the method comprises building a slowness filter for removing the coherent noise, and applying the slowness filter to the plurality of waveforms.

Processes and systems described herein are directed to imaging a subterranean formation from seismic data recorded in a marine survey with moving marine vibrators. The marine vibrators generate random sweeps with random sweep signatures. Processes and systems generate an up-going pressure wavefield from measured pressure and vertical velocity wavefield data recorded in the marine survey and obtain a downgoing vertical acceleration wavefield that records source wavefields, directivity, source ghosts, and random signatures of the random sweeps. The downgoing vertical acceleration wavefield data is deconvolved from the up-going pressure wavefield to obtain a subsurface reflectivity wavefield that is used to generate an image of the subterranean formation with reduced contamination from source wavefields. directivity, source ghosts, and random signatures of the random sweeps.

A system and method for reducing migration distortions in migrated images of the Earth's subsurface. Recorded seismic data may be migrated, using a migration velocity model, to generate a migration image comprising distortions. Synthetic seismic data may be generated, using the migration velocity model, for a grid of scattered points. The synthetic seismic data may be migrated, using the migration velocity model, to generate impulse responses for the scattered points. The impulse responses are used as point spread functions (PSFs) which approximates the blurring operator, e.g., the Hessian operator. An optimal reflectivity model may be selected using image-domain least-squares migration (LSM), based on the PSFs, with a regularization of the difference between the migration image and a reflectivity model and a total variation (TV) regularization of the reflectivity model. An image of the optimal reflectivity model may be generated that has reduced migration distortions compared to the original migration image.

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.

A method includes acquiring seismic data of a region that utilizes multiple seismic energy sources and seismic energy receivers where the seismic data include blended seismic data for a number of emissions from a corresponding number of the multiple seismic energy sources; determining spatially distributed coherent noise properties for the region using the blended seismic data; via the spatially distributed coherent noise properties, modeling coherent noise as at least two coherent noise models for at least two of the emissions from a corresponding at least two of the multiple seismic energy sources; via the coherent noise models, attenuating coherent noise in a portion of the blended seismic data to generate coherent noise attenuated blended seismic data; deblending the coherent noise attenuated blended seismic data to generate deblended seismic data; and rendering an image of at least a portion of the region to a display using the deblended seismic data.

Processes and systems are described for generating an image of a subterranean formation from seismic data recorded during a marine survey that employed a moving vibrational source. Processes and systems compute an up-going pressure wavefield from pressure data and vertical velocity data recorded in the marine survey. A direct incident downgoing vertical velocity wavefield that includes Doppler effects created by the moving vibrational source and characterizes a source wavefield and source ghost of the moving vibrational source is computed and deconvolved from the upgoing pressure wavefield to generate a subsurface reflectivity wavefield. The subsurface reflectivity wavefield is effectively free of contamination from the source wavefield, the source ghost, and the Doppler related effects. Processes and systems generate an image of the subterranean formation based on the subsurface reflectivity wavefield, thereby enhancing resolution of the image by attenuating the source-motion effects, source signature, and source ghost of the moving vibration source.

A method for deblending seismic signals includes entering as input to a computer recorded signals comprising seismic energy from a plurality of actuations of one or more seismic energy sources. A model of deblended seismic data and a blending matrix are initialized. A blending matrix inversion is performed using the initialized model. The inversion includes using a scaled objective function. The inversion is constrained by a thresholding operator. The thresholding operator is arranged to recover coefficients of the model of the deblended seismic data that are substantially nonzero, against a Gaussian white noise background. The thresholded model is projected into data space. Performing the blending matrix inversion is repeated if a data residual exceeds a selected threshold and the inversion is terminated if the data residual is below the selected threshold. At least one of storing and displaying an output of the blending matrix inversion is performed when the blending matrix inversion is terminated.

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.