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The issue of receiver ghosts is long-standing in the seismic industry. Basically, streamers towed at shallow depths give the high-end frequency content needed for resolution. However, they attenuate the low-end frequency required for deep penetration, in addition to making the data more susceptible to swell noise. Deep streamer towing, alternatively, enhances low frequencies but attenuates high frequencies. With deep towing, swell and ambient noise are reduced. These frequency issues cause receiver ghosts, which are the part of the signal that reflects off the water surface and is subsequently recorded on its way down by the streamer.

Ghosts have, traditionally, proved difficult to eliminate through data processing, leading to attempts to eliminate them in acquisition through methods, such as slanted-streamer towing, dual sensors and ocean-bottom sensor placement. Yet, the problem is not fully solved. Nowhere is that better illustrated than in the number of patents filed for deghosting solutions in 2013 alone. Below is a partial list.

A. 11/21/13; Patent 20130308420; Pre-stack deghosting of seismic data. The method includes receiving the seismic data recorded by detectors distributed along a variable-depth profile; calculating migrated (d1) and mirror-migrated (d2) gathers based on the seismic data, wherein the migrated and mirror-migrated gathers depend on a feature characterizing a configuration of the seismic system; applying a joint deconvolution model to the migrated and mirror-migrated gathers (d1, d2) to calculate a single deghosted gather (dg); and generating a final image of the subsurface based on the single deghosted gather (dg).

B. 10/31/13; Patent 20130286777; Generating deghosted seismic data. One embodiment relates to a method for deghosting seismic data from a marine seismic survey. The data from the marine seismic survey are obtained, where the marine seismic survey was performed using multiple sub-sources towed at two or more different depths, and fired at distinct time-delays.

C. 10/24/13; Patent 20130282292; Premigration deghosting of seismic data with a bootstrap technique. Methods and systems for optimized receiver-based ghost filter generation are described. The optimized ghost filter self-determines its parameters, based on an iterative calculation of recorded data transformed from a time-space domain to a tau-p domain.

D. 10/24/13; Patent 20130279290; Deghosting variable depth streamer data. The method may include receiving input seismic data recorded by seismic receivers located at different depths (zr), generating migration data (du) and mirror migration data (dd) from the input seismic data, deriving a ghost-free model (m) based on simultaneously using the migration data (du) and mirror migration data (dd), generating primary (p) and ghost (g) datasets based on the ghost free model (m), simultaneously adaptively subtracting the primary (p) and ghost (g) datasets from the migration data (du) to provide adapted primary (p′1 and p′2) and adapted residual (r′1 and r′2) datasets and generating a final image (f) of the subsurface based on the adapted primary (p′1 and p′2) and the adapted residual (r′1 and r′2) datasets.

E. 08/29/13; Patent 20130226463; Deghosting marine seismic wavefields using cost-functional minimization. In one aspect, the method computationally transforms recorded wavefield data from the space-time domain to a wavenumber-frequency domain and computationally deghosts the wavefield data in the wavenumber-frequency domain.

F. 07/18/13; Patent 20130182536; Wavefield deghosting. A technique includes receiving sensor acquired data, which includes pressure data representative of at least one pressure measurement of a wavefield and particle motion data representative of at least one particle motion measurement of the wavefield. The technique includes filtering the pressure data and the particle motion data with a plurality of directional filters to provide a plurality of filtered datasets.

G. 07/11/13; Patent 20130176818; Variable-depth streamer srme. Methods and systems for variable wavelet correction are described. A variable depth dataset is deghosted before presentation to a multiples prediction step of multiples elimination model.

H. 05/30/13; Patent 20130135966; Acquisition and processing of multi-source, broadband, marine seismic data. A method and system of acquiring and processing multi-source, broadband, marine seismic data so that at least a part of said acquired data is partially or fully de-ghosted on the receiver side and then partially or fully re-assembled to a pre-stack dataset. At least one non-uniformly horizontal streamer is towed. At least two seismic sources emit seismic signals at spaced positions.

I. 05/23/13; Patent 20130128695; Deghosting p-waves. Computing device and method for determining primary and ghost components from recorded p-waves. The method includes receiving seismic data (r, v) with regard to the p-waves, wherein the seismic data include vertical and radial components recorded with a buried two-component receiver; calculating with a processor a primary component (p) and a ghost component (g) from the vertical and radial components; and computing an image of a subsurface based on the primary and ghost components (p, g).

J. 01/31/13; Patent no. 20130028049; Handling rough sea and irregular recording conditions in multi-sensor, towed streamer data. Rough sea elevation is estimated from a high-frequency portion of recorded pressure data and recorded vertical velocity component data. Generalized deghosting and datuming operators are constructed, which consider estimated rough sea elevation and irregular recording depths.