A method of generating target-oriented acquisition-imprint-free prestack angle gathers using common focus point (CFP) operators includes receiving a plurality of seismic traces associated with a target point in a reservoir. A first angle domain common image gather (ADCIG) is generated based on the received plurality of seismic traces. A plurality of synthetic traces associated with the target point is generated. A second ADCIG is generated based on the synthetic traces. An enhanced ADCIG is generated using the first ADCIG and the second ADCIG.

Methods are described for separating the unknown contributions of two or more sources from a commonly acquired aliased wave field signals including the determination of models with reduced support in the frequency-wavenumber domain which reconstruct the wave fields of independently-activated sources after a coordinate-transform of the acquired wave field data and/or in a coordinate-transformed domain.

Simultaneous sources are separated with a deblending method wherein the fullband data deblended on a source-by-source basis. The fullband data is first decomposed into multiple subbands, and then a non-equispaced subband Radon transform is used to transform the decomposed data into the Radon domain. The deblending process is solved subband by subband by minimising a nonlinear objective function. The solution of the nonlinear objective function is found using a multi-step procedure.

Post-stack seismic data is received. Transformed seismic data is created from the received post-stack seismic data, including performing a super-resolution radon transform on the post-stack seismic data. Signal and noise regions are separated using the transformed seismic data, including using a defined muting function to remove unwanted noise. An inverse radon transform is performed using the separated signal and noise regions, outputting only signals.

An input seismic data set is obtained, and a first inversion is conducted on a first frequency filtered input seismic data set across all slowness values in the plurality of slowness values using an inversion matrix with dipole modulation containing a plurality of Tau-p operators and a plurality of dipole terms to transform the first frequency filtered input seismic data set from a time domain to a Tau-p domain having a plurality of first inversion Tau-p coefficients. Each Tau-p coefficient associated with one of the plurality of slowness values. The first inversion Tau-p coefficients are used to identify a subset of slowness values from the plurality of slowness values, and iterative sparse Tau-p inversion using the identified subset of slowness values is performed. The input seismic data set is modified to generate a noise attenuated seismic data set based on the iterative sparse Tau-p inversion.

Computing device, computer instructions and method for up-down separation of seismic data. The method includes receiving the seismic data, which includes hydrophone data and particle motion data; performing a first up-down separation, which is independent of a ghost model, using as input the hydrophone data and the particle motion data, to obtain first up-down separated data; performing a second up-down separation by using as input a combination of (i) the hydrophone data and/or the particle motion data and (ii) the first up-down separated data, wherein an output of the second up-down separation is second up-down separated data; and generating an image of the subsurface based on the second up-down separated data.