In some embodiments, a seismic processing method comprises assembling a specularity gather by determining a specularity value at each of a plurality of subsurface locations, and summing trace amplitudes into a plurality of bins, each bin characterized by a range of specularity values. The specularity value at a subsurface location is computed according to an angle between a normal to a local reflector and a direction of a total (source+receiver) traveltime gradient. For example, the specularity may be proportional to (e.g. equal to) a magnitude of the cosine of the angle. A diffraction image may be generated by summing specularity gather data over specularity, with specular event amplitudes attenuated relative to diffractive event amplitudes.

A method of obtaining an equivalent tool model includes obtaining a set of known well data, in which the known well data includes sensor data measured by a logging tool and an actual dispersion response, and the logging tool has an actual tool size. The method also includes obtaining one or more well parameters from the known well data, and inputting the one or more well parameters and a model tool size into a rigid tool model. The method further includes obtaining an estimated dispersion response from the rigid tool model, and fitting the estimated dispersion response to the actual dispersion response by adjusting the model tool size.

A method for estimating a far field seismic energy source signature includes using detected near field seismic signals corresponding to actuation of each one of a plurality of seismic energy sources in an array of seismic energy sources. The near field seismic signals are detected at two spaced apart locations in the near field of each seismic energy source, the at least two spaced apart locations being arranged such that a direction of propagation of the detected near field seismic signals is determinable from the detected near field signals. A notional source signature for each seismic energy source and a notional ghost for each seismic energy source using the detected near field seismic signals. A far field signature is determined for the plurality of seismic energy sources using the determined notional source signature and notional ghost signature from each seismic energy source.

A method for removing multiples m from seismic data d associated with a subsurface, the method including receiving the seismic data d associated with the subsurface, forward propagating the seismic data d into the subsurface to form forward propagated data d.sub.?; receiving angular dependent reflectivities r.sub.?, associated with an angular range ??, in the subsurface, for a given point; generating an angle dependent reflecting wavefield D.sub.??r.sub.? based on the forward propagated data d.sub.? and the angular dependent reflectivities r.sub.?; calculating a multiple model ?D.sub.??r.sub.? by forward propagating the angle dependent reflecting wavefield D.sub.??r.sub.? to the receiver; attenuating multiplies m associated with the multiple model, from the seismic data d, by subtraction of the multiple model to calculate demultiple data dd; and generating an image of the subsurface.

Processes and systems for generating images of a subterranean formation from recorded seismic data obtained in a marine survey are described. Processes and systems compute reverse-time receiver-motion-corrected upgoing and downgoing pressure wavefields at different locations of corresponding upgoing and downgoing observation levels based on the recorded seismic data. The reverse-time receiver-motion-corrected upgoing and downgoing pressure wavefields are time forwarded and extrapolated to obtain a corresponding receiver-motion-corrected upgoing and downgoing pressure wavefields at locations of a static observation level. An image of the subterranean formation is generated based at least in part on the receiver-motion-corrected upgoing pressure wavefield and the receiver-motion-corrected downgoing pressure wavefield.

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.

A method for obtaining zero-offset and near zero offset seismic data from a marine survey, with separation of direct arrival information and reflectivity information, the method including: modeling a direct arrival estimate at a passive near-field hydrophone array by using a notional source separation on active near-field hydrophone data; generating reflection data for the passive near-field hydrophone array by subtraction of the modeled direct wave from data recorded by the passive near-field hydrophone array; generating near zero-offset reflectivity traces by stacking the reflection data for the passive near-field hydrophone array on a string-by-string basis or on a combination of strings basis.

A method for refraction-based surface-consistent amplitude compensation and deconvolution includes receiving seismic traces, the seismic traces generated using at least one source and at least one receiver; calculating an amplitude residual for each seismic trace; determining surface-consistent amplitude residuals for the at least one source and the at least one receiver based on the amplitude residual for each seismic trace; and performing surface-consistent amplitude correction to each seismic trace by applying the determined surface-consistent amplitude residuals for the at least one source and the at least one receiver.

A notional source signature of a bubble may be determined. For example, a method for determining a notional source signature of a bubble can include estimating a position of a bubble created by actuation of an impulsive source. A notional source signature of the bubble can be determined based on the estimate.

A method is described for modifying an earth model including receiving an earth model containing one or more surfaces with surface geometries, such that at least two surface depth locations exist for some horizontal positions; perturbing elastic properties within the earth model; and generating a modified earth model by modifying the surface geometries within the earth model while preserving seismic travel times of the earth model such that after an initial user parameterization all updates of the surfaces are done without additional user input. The method may be executed by a computer system.