Abstract: An inline source can be used for a marine survey. For example, a marine survey vessel can tow source units in line. The source units can be actuated near-continuously to cause a respective signal emitted by each of the source units to be uncorrelated with signals emitted by other of the source units.

Abstract: This disclosure is directed to methods and systems to evaluate noise contend of seismic data received during a marine survey. The seismic data includes pressure and particle motion data generated by collocated pressure and particle motion sensors of a seismic data acquisition system. The pressure and particle motion data are cross ghosted and temporal and spatial wavelet transforms are applied to the cross-ghosted pressure and particle motion data in order to compute pressure energies and particle motion energies in temporal and spatial scales of a temporal and spatial scale domain. The pressure and particle motion energies may be compared to evaluate noise content in the pressure and particle motion data, evaluate changes in the noise content during the marine survey, and adjust marine survey parameters to reduce the noise content.

Abstract: 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.

Abstract: A data set representing features of a geologic formation is formed from two or more signal acquisition data set representing independent aspects of the same wavefield. A wavelet transform is performed on the two or more signal acquisition data sets, and the data sets are further transformed to equalize signal portions of the data sets. Remaining differences in the data sets are interpreted as excess noise and are removed by different methods to improve the signal-to-noise ratio of any resulting data set.

Abstract: A data set representing features of a geologic formation is formed from two or more signal acquisition data set representing independent aspects of the same wavefield. A wavelet transform is performed on the two or more signal acquisition data sets, and the data sets are further transformed to equalize signal portions of the data sets. Remaining differences in the data sets are interpreted as excess noise and are removed by different methods to improve the signal-to-noise ratio of any resulting data set.

Abstract: This disclosure is directed to methods and systems to evaluate noise contend of seismic data received during a marine survey. The seismic data includes pressure and particle motion data generated by collocated pressure and particle motion sensors of a seismic data acquisition system. The pressure and particle motion data are cross ghosted and temporal and spatial wavelet transforms are applied to the cross-ghosted pressure and particle motion data in order to compute pressure energies and particle motion energies in temporal and spatial scales of a temporal and spatial scale domain. The pressure and particle motion energies may be compared to evaluate noise content in the pressure and particle motion data, evaluate changes in the noise content during the marine survey, and adjust marine survey parameters to reduce the noise content.

Abstract: 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.

Abstract: A data set representing features of a geologic formation is formed from two or more signal acquisition data set representing independent aspects of the same wavefield. A wavelet transform is performed on the two or more signal acquisition data sets, and the data sets are further transformed to equalize signal portions of the data sets. Remaining differences in the data sets are interpreted as excess noise and are removed by different methods to improve the signal-to-noise ratio of any resulting data set.

Abstract: Filters are applied to seismic signals representative of subsurface formations to generate filtered signals with attenuated spatially aliased energy. The filtered signals are multiplied in the frequency-wavenumber domain by a complex function of frequency and wavenumber representing the seismic attribute in the frequency-wavenumber domain, to generate scaled signals. The scaled signals, transformed to the time-space domain, are divided by the filtered signals in the time-space domain, to a seismic attribute useful for identifying and characterizing the subsurface formations.

Abstract: A cross-line slowness is determined for each sample in the signals in towed marine seismic streamers. A range of assumed cross-line slownesses is selected. Vertical wavenumbers are determined using the range of assumed cross-line slowness determined for samples in the signals of pressure sensors and particle motion sensors in the towed marine seismic streamers. The determined vertical wavenumbers are used to correct the particle motion sensor signals for angle of incidence along the direction of the seismic streamers and transverse thereto to generate a corrected particle motion sensor signal. The corrected particle motion sensor signals are combined based on the determined cross-line slowness for the samples. The corrected particle motion sensor signal and the pressure sensor signal are used to determine at least one of upgoing and downgoing pressure components and upgoing and downgoing particle motion components of the particle motion sensor and pressure sensor seismic signals.

Abstract: A first weighted integral operator is applied to dual-sensor data to extrapolate the dual-sensor data to a first position above an acquisition surface, generating extrapolated data. A second weighted integral operator is applied to the extrapolated data to extrapolate the extrapolated data to a second position, generating wavefield separated data. One of the integral operators is applied to a scaled combination of the dual sensor data.

Abstract: A method for determining upgoing pressure components of seismic signals from signals detected by combined pressure responsive sensors and motion responsive seismic sensors disposed in a plurality of laterally spaced apart streamers includes determining a threshold time at which angle of incidence error in the motion responsive signals in the cross-line direction falls below a selected threshold. Below the threshold time, the motion responsive signals are corrected for angle of incidence in the in-line and cross-line directions. Above the threshold time, the motion responsive signals are corrected for angle of incidence only in the in-line direction. Both sets of incidence corrected measured motion responsive signals, and the pressure responsive signals are used to determine upgoing or downgoing pressure components or upgoing or downgoing motion components of the measured motion responsive and pressure responsive seismic signals.

Abstract: A cross-line slowness is determined for each sample in the signals in towed marine seismic streamers. A range of assumed cross-line slownesses is selected. Vertical wavenumbers are determined using the range of assumed cross-line slowness determined for samples in the signals of pressure sensors and particle motion sensors in the towed marine seismic streamers. The determined vertical wavenumbers are used to correct the particle motion sensor signals for angle of incidence along the direction of the seismic streamers and transverse thereto to generate a corrected particle motion sensor signal. The corrected particle motion sensor signals are combined based on the determined cross-line slowness for the samples. The corrected particle motion sensor signal and the pressure sensor signal are used to determine at least one of upgoing and downgoing pressure components and upgoing and downgoing particle motion components of the particle motion sensor and pressure sensor seismic signals.

Abstract: Pressure records and vertical particle velocity records from dual sensor towed streamer data are transformed to the inline wavenumber domain. A series of scaling filters are applied to the transformed vertical particle velocity records at each inline wavenumber, wherein each of the series of scaling filters is calculated for a different cross-streamer wavenumber range and in blocks of inline traces in which all seismic events are approximately linear. The pressure spectrum and the scaled vertical particle velocity spectrum are combined to separate upgoing and downgoing wavefield components. The separated upgoing and downgoing wavefield components are inverse-transformed back to the time-space domain.