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 traverse general, related activation lines or grids and are synchronously activated while varying at least one parameter between the sources.

The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for removing false image in reverse time migration (RTM). One computer-implemented method includes dividing volume of a source wavefield and a receiver wavefield into a plurality of windows, calculating a down-going component of the source wavefield and an up-going component of the receiver wavefield for each window in the plurality of windows and at a particular value of time, calculating a down-going component of the source wavefield at the particular value of time by summing the down-going component of the source wavefield in each window of the plurality of windows, and calculating an up-going component of the receiver wavefield at the particular value of time by summing the up-going component of the receiver wavefield in each window of the plurality of windows.

Methods of analyzing and optimizing a seismic survey design are described. Specifically, the sampling quality is analyzed as opposed to the overall quality of the whole survey. This allows for analysis of the impact of the offsets, obstacles, and other aspects of the survey on the sampling quality, which will improve the ability to compress the resulting data and minimize acquisition footprints.

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.

Suppressing data corresponding to noise using a model of noise propagation along a sensor streamer. At least some of the example embodiments are methods including: reading a data set containing noise and seismic signals recorded by geophones disposed in a sensor streamer when the sensor streamer was within a body of water; determining locations of noise sources along the sensor streamer when the sensor streamer was within the body of water; and suppressing data of the data set corresponding to noise sources along the sensor streamer.

A method and apparatus for separating the unknown contributions of two or more sources from a commonly acquired wave field including the determination of a wavenumber dependent model which reconstructs the wave field of the sources independently below a frequency set by the slowest physical propagation velocity, and applying an inversion based on the model to the commonly acquired wave field to separate the contributions.

Method for correcting seismic simulations, RTM, and FWI for temporal dispersion due to temporal finite difference methods in which time derivatives are approximated to a specified order of approximation. Computer-simulated seismic data (51) are transformed from time domain to frequency domain (52), and then resampled using a mapping relationship that maps, in the frequency domain, to a frequency at which the time derivative exhibits no temporal dispersion (53), or to a frequency at which the time derivative exhibits a specified different order of temporal dispersion. Alternatively, measured seismic data from a field survey (61) may have temporal dispersion of a given order introduced, by a similar technique, to match the order of approximation used to generate simulated data which are to be compared to the measured data.

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.

Methods and systems to remove source wavefield and source ghost effects from marine seismic data are described. The methods and systems may be used to substantially remove source wavefield and source ghost effects from marine seismic data collected in rough weather conditions.

Methods and systems to determine ghost operators from marine seismic data are described. Methods and systems extract statistical information about the free surface from N gathers of pressure and vertical velocity data obtained for N activates of a source. Ghost operators are calculated from the N gathers of pressure and vertical velocity data. The ghost operators may be used to characterize the actual source and receiver ghosts recorded in the seismic data, compute properties of the free surface, such a reflection coefficient and root mean square free surface height, and may be used to deghost pressure and vertical velocity data.