Abstract: Controller and method for determining a driving signal of a vibro-acoustic source element that is configured to generate acoustic waves in water. The method includes estimating at least one physical constraint of the vibro-acoustic source element; modeling a ghost function determined by a surface of the water; setting a target energy spectrum density to be emitted by the vibro-acoustic source element during the driving signal; and determining the driving signal in a controller based on at least one physical constraint, the ghost function, and the target energy spectrum density.

Abstract: Methods and systems for compensating for source and receiver ghost effects in a reverse time migration (RTM) equation are described. Boundary conditions associated with the RTM acoustic wave equations for the source and recorded wavefields are modified. The resultant modified RTM acoustic wave equations are solved to generate ghost compensated modeled seismic images. In another aspect an imaging condition is also modified and the resultant RTM acoustic wave equations are solved to generate velocity and impedance perturbation images.

Abstract: A method and a catenary seismic source steering gear for towing seismic sources underwater. The catenary gear includes plural seismic sources configured to generate seismic waves underwater; a main rope configured to span between first and second vessels; and a connecting system configured to connect the plural seismic sources to the main rope. The main rope takes a substantially catenary shape when towed by the first and second vessels underwater.

Abstract: A system and method are described herein for generating a frequency sweep signal set for use in seismic data gathering. Low frequency sweep rate modifications are combined to compensate for vibrator limitations and vibrator far-field responses with high frequency sweep rate modifications to compensate for absorption, and then the frequency sweep signal set is generated based on the combination of high and low frequency sweep rate modifications.

Abstract: Methods and apparatuses for processing seismic data carrying information about a subsurface structure are provided. One method includes splitting the seismic data in groups, each group including subsets of seismic data for which a distance from a respective shot point to a receiver line in a patch of active detectors corresponding to the shot point is within a predetermined range for the group, and extracting signal data for each block Hankel matrix based on an SVD analysis thereof. Another method includes extracting signal data by subtracting from seismic data an estimated noise model obtained by rank reduction of a Hankel matrix followed by dip filtering, enhanced based on a least square matching filter with the seismic data.

Abstract: A seismic survey system for recording seismic data underwater. The system includes first plural buoys configured to descend to a first predetermined depth (H1) in water, at least one buoy having a seismic receiver for recording the seismic data; a first vessel configured to launch the first plural buoys; and a first acoustic system attached to the first vessel and configured to detect a position of the at least one buoy while underwater. The at least one buoy is instructed to maintain the first predetermined depth (H1) underwater while recording the seismic data.

Abstract: Method for determining a seismic survey configuration of a multi-vessel acquisition system. The method includes a step of receiving number that corresponds to vessels to be used in the multi-vessel acquisition system; a step of receiving a cross-line distance between first and last straight line paths corresponding to first and last vessels, respectively, of the multi-vessel acquisition system; a step of receiving an inline distance between the first and last vessels; a step of selecting shapes of undulating paths for the vessels of the multi-vessel acquisition system; a step of receiving a desired azimuth and/or offset distribution of receivers towed by one or more streamer vessels of the multi-vessel acquisition system relative to source vessels of the multi-vessel acquisition system; and a step of calculating amplitudes (Ai), periods (Ti) and phases of the undulating paths.

Abstract: A buoy for recording seismic signals while underwater. The buoy includes a body; a buoyancy system configured to control a buoyancy of the body to descend to a predetermined depth (H1); a propulsion system configured to actively adjust a position of the body at a given position (X, Y); a seismic sensor located on the body and configured to record the seismic signals; and a control device configured to control the buoyancy system to maintain the body substantially at the predetermined depth (H1) and to control the propulsion system to maintain the body substantially at the given position (X, Y) while the buoy records seismic data, and also to instruct the seismic sensor when to record seismic signals.

Abstract: A seismic survey system for recording seismic data underwater in the presence of underwater currents. The system includes first plural buoys configured to descend in water at a predetermined depth (H1) and each having a seismic receiver for recording the seismic data; a first vessel configured to launch the first plural buoys along a first line; and a second vessel configured to recover the first plural buoys at a second line, wherein there is a predetermined distance between the first and second lines. The first plural buoys are configured to travel underwater, at substantially the first predetermined depth (H1), from the first line to the second line, due exclusively to the underwater currents.

Abstract: A method, an apparatus and a computer readable medium for generating an image of a subsurface based on seismic data corresponding to at least two different times, for a same surveyed area are provided. A cost function, which is a sum over the seismic data vintages of a norm of differences between data and model predicted multiples, is minimized subject to minimizing residual multiples that are differences of corresponding multiples belonging to different vintages among the seismic data vintages.

Abstract: Computing device and method for calculating time-shifts associated with travel-times of seismic waves emitted by a source and recorded by plural seismic detectors after reflection from a subsurface structure. The method includes receiving seismic data (d) that includes plural traces related to a subsurface, wherein the seismic data (d) is in a time-space domain; transforming with a processor the seismic data (d) from the time-space domain to a radon domain; picking linear events from the seismic data in the radon domain; calculating the time-shifts associated with the picked linear events; correcting the seismic data (d) based on the time-shifts to obtain new seismic data (d?); and computing an image of the subsurface based on the new seismic data (d?). The time-shifts are calculated per trace and per event.

Abstract: A system and method are disclosed for substantially eliminating the influence of internal multiples when seismic mapping under-water geographical areas of interest without a priori knowledge of subsurface information. The system and method iteratively locate multiple-generating horizons for predicting internal multiples and uses a lower-higher-lower relationship between the multiple generating horizons. The system and method provide an appropriate and cost-effective means for internal multiple attenuation without subsurface information.

Abstract: A marine node for recording seismic waves underwater. The node includes a spherical body made of a material that has a density similar to a density of the water so that the body is buoyant neutral; a first sensor located in the body and configured to record three dimensional movements of the node; a second sensor located in the body and configured to record pressure waves propagating through the water; and one or more cables connected to the first and second sensors and configured to exit the body to be connected to an external device. The body is coupled to the water.

Abstract: Computing device, computer instructions and method for denoising marine seismic data recorded with first and second seismic sensors. The method includes receiving first seismic data recorded with the first sensor in a time-space domain; receiving second seismic data recorded with the second sensor in the time-space domain, wherein the first and second seismic data are recorded at the same locations underwater; calculating with a processor models of the first and second seismic data in a transform domain that is different from the time-space domain; performing a wavefield separation using the first and second datasets in the transform domain; determining a noise in the transform domain corresponding to the second seismic data based on the wavefield separation; reverse transforming the noise from the transform domain into the time-space domain; and denoising the second seismic data by subtracting the noise in the time-space domain from the second seismic data.

Abstract: Computing device, computer instructions and method for deghosting seismic data related to a subsurface of a body of water. The method includes receiving seismic data recorded by seismic receivers that are towed by a vessel, wherein the seismic data is recorded in a time-space domain; modeling the seismic data in a shot or common midpoint domain as a function of operators to derive a model; using the derived model to remove the receiver ghost from the seismic data to obtain deghosted seismic data; and generating a final image of the subsurface based on the deghosted seismic data.

Abstract: A marine acoustic source system and method for steering a seismic source array in a body of water during a seismic survey. The method includes measuring an actual position of the seismic source array; calculating a virtual position of the seismic source array, wherein the virtual position corresponds to a position of the seismic source array when towed with no adjustment from a source steering device; retrieving a pre-plot path that includes desired positions of the seismic source array for the seismic survey; and steering the vessel based on the virtual position so that the virtual position lies on the pre-plot path.

Abstract: A buoy is configured to record seismic signals while underwater. The buoy includes a body; a buoyancy system configured to control a buoyancy of the body to descend multiple times to a predetermined depth (H) and then resurface with a controlled speed; and a seismic sensor located in the body and configured to record the seismic signals. The seismic sensor is instructed to record the seismic signals as the buoy travels up and down between the water surface and the predetermined depth.

Abstract: System and method for actuating first and second marine acoustic sources in a firing sequence, the firing sequence including at least a first actuation of the first source followed by a first actuation of the second source followed by a second actuation of the first source and a second actuation of the second source. The method includes towing the first source at a depth in water substantially equal to a depth of the second source; establishing a series of reference time instants; actuating the first source with a variable first time delay relative to the series of reference time instants; and actuating the second source with a variable second time delay relative to the series of reference time instants such that time intervals between consecutive activations of the first and second sources are also variable.

Abstract: Apparatus, computer instructions and method for separating up-going and down-going wave fields (U, D) from seismic data recorded within or beneath a body of water, or in general below the surface of the earth. The method includes a step of receiving seismic data (Po, Zo) recorded in the time-space domain with seismic recorders distributed on a first datum, wherein the first datum is non-flat; a step of establishing a mathematical relation between transformed seismic data (P, Z) and the up-going and down-going wave fields (U, D) on a second planar datum; and a step of solving with an inversion procedure, run on a processor, the mathematical relation to obtain the up-going and down-going wave fields (U, D) for the second datum. The second datum is different from the first datum.

Abstract: A method and a marine towing system for towing streamers or sources. The towing system includes a connecting line; a first paravane connected to the connecting line, wherein the connecting line is configured to connect the first paravane to a vessel; a spur line connected to the first paravane and configured to provide a tension to maintain streamers apart from each other; and a second paravane connected to the connecting line, between the first paravane and the vessel. The second paravane is configured to increase an angle (?4) between the connecting line and the spur line.