Abstract: Source element of a source subarray can be individually actuated according to an actuation sequence. The actuation sequence can be at least partially based on a relative position of each of the source elements within a particular geometry of the source subarray with respect to a previously actuated source element and a towing velocity of the source subarray.

Abstract: A method for marine seismic surveying includes separating up-going and down-going wavefields from seismic energy emitted by at least one marine seismic energy source. The separated up-going and down-going wavefields are propagated from the at least one marine seismic energy source to at least one of a water surface and a common reference depth. One of the up-going and down-going wavefields is phase shifted 180 degrees. The propagated, phase shifted up-going and down-going wavefields are summed.

Abstract: Estimation of direct arrival signals based on predicted direct arrival signals and measurements can include obtaining notional source signatures for notional sources that correspond to source elements in a seismic source. A first predicted direct arrival signal at a first location and a second predicted direct arrival signal at a second location can be determined. The first location corresponds to a seismic receiver and the second location does not correspond to a seismic receiver. A transfer function can be determined based on the first predicted direct arrival signal at the first location and the second predicted direct arrival signal at the second location. An estimated direct arrival signal at the second location can be determined based on the transfer function and a measurement by the seismic receiver corresponding to the first location. The estimated direct arrival signal represents what a measured direct arrival signal would be at the second location.

Abstract: At least some embodiments are directed to a system. The system includes a processor and a memory coupled to the processor. The memory stores a program that, when executed by the processor, causes the processor to calculate a pressure response of a first sensor, and correct pressure wavefield data obtained from the first sensor responsive to a first acoustic wavefield. The correction is based on the calculated pressure response of the first sensor. The pressure response of the first sensor is responsive to a second acoustic wavefield having a propagation path between a source of the second acoustic wavefield and the first sensor, in which the propagation path includes no reflection from a subsurface formation.

Abstract: Estimation of direct arrival signals based on predicted direct arrival signals and measurements can include obtaining notional source signatures for notional sources that correspond to source elements in a seismic source. A first predicted direct arrival signal at a first location and a second predicted direct arrival signal at a second location can be determined. The first location corresponds to a seismic receiver and the second location does not correspond to a seismic receiver. A transfer function can be determined based on the first predicted direct arrival signal at the first location and the second predicted direct arrival signal at the second location. An estimated direct arrival signal at the second location can be determined based on the transfer function and a measurement by the seismic receiver corresponding to the first location. The estimated direct arrival signal represents what a measured direct arrival signal would be at the second location.

Abstract: Seismic data are acquired using a seismic source comprising a plurality of seismic sub-sources disposed in a body of water at a plurality of depths and activated with different time delays. Far-field signatures are determined for the plurality of seismic sub-sources at each of the plurality of depths. A composite ghost-free far-field signature of the seismic source is determined from the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths and different time delays.

Abstract: Techniques are disclosed relating to testing of seismic air guns, for example via bubble tests. According to some embodiments of these techniques, a firing sequence for testing the air guns may be determined that reduces the amount of interaction between firings. Further, firing time delays may also be determined in order to further reduce the interactions. Accordingly, a test of an array of air guns may be completed relatively quickly.

Abstract: Included are methods and systems for marine geophysical surveying. A system includes a streamer; a sensor package coupled to the streamer, wherein the sensor package comprises a primary orientation sensor and a complimentary orientation sensor, wherein the complimentary orientation sensor comprises a magnetometer, wherein the primary orientation sensor and the complimentary orientation sensor are capable of collecting data indicative of the orientation of the streamer; and geophysical sensors distributed on the streamer.

Abstract: Computational methods and systems for deghosting marine seismic streamer data are described. In particular, an exploration-seismology vessel tows a number of streamers that form a data acquisition surface located beneath a free surface. The methods computationally deghost or substantially remove receiver ghost signals from seismic data recorded by steamer receivers. The deghosting methods include low frequency compensation to recover vertical velocity wavefield information that is typically lost due to a low signal-to-noise ratio over a low frequency range independent of the free surface conditions or the shape of the data acquisition surface.

Abstract: Seismic data are acquired using a seismic source comprising a plurality of seismic sub-sources disposed in a body of water at a plurality of depths and activated with different time delays. Far-field signatures are determined for the plurality of seismic sub-sources at each of the plurality of depths. A composite ghost-free far-field signature of the seismic source is determined from the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths and different time delays. A source response is removed from the seismic data using the far-field signatures of the seismic source.

Abstract: This disclosure is directed to systems and methods of wavefield separation based on matching operators that represents the relationship between co-located pressure and particle motions sensors. A pressure wavefield and a particle motion wavefield emitted from a subterranean formation are measured using co-located pressure and particle motion sensors located along one or more streamers of a seismic data acquisition system. A matching operator that relates pressure sensor and particle motion sensor responses for co-located pressure and particle motion sensors is computed based on depth of the co-located pressure and particle motion sensors and on the measured pressure and particle motion wavefields. The matching operator and the measured pressure and particle motion wavefields may then be used to compute up-going and down-going wavefields.

Abstract: Systems and methods for operating a seismic source to attenuate shot generated noise, or residual energy from previous activation of the source, in recorded seismic data are described. In one aspect, methods operate a single seismic source towed through a body of water along a survey track. As the survey vessel travels along the survey track, the source is activated at the end of randomly selected time delays, resulting in attenuation of shot generated noise. The method also attenuates other forms of coherent noise that align from shot to shot.

Abstract: Methods and systems that attenuate noise in seismic data. In one aspect, noise attenuation methods iteratively generate a low-speed noise model of low-speed noise recorded in the seismic data. The seismic data is arranged into a sparse seismic-data matrix. Low-speed noise refers to noise that propagates at speeds less the speed of sound in water. The low-speed noise model includes the low-speed noise and includes interpolated low-speed noise that approximates portions of the low-speed noise typically affected by spatial aliasing and streamer surface irregularities. The low-speed noise model may be subtracted from the sparse seismic-data matrix to obtain a noise-attenuated sparse seismic-data matrix.

Abstract: Systems and methods for imaging subterranean formations using primary and multiple reflections are described. An exploration-seismology vessel tows a seismic source, a receiver acquisition surface located beneath a free surface, and a source acquisition surface positioned at a depth below the source. The receiver acquisition surface is used to measure pressure and normal velocity wavefields and the source acquisition surface is used to measure direct, down-going, source pressure wavefields generated by the source. The down-going source pressure wavefields in combination with the down-going pressure wavefields and up-going pressure wavefields computed from the pressure and velocity wavefields are used to compute images of the subterranean formation associated with primary reflections and multiple reflections.

Abstract: In order to avoid complicated and unpredictable effects on the wavefields emitted by air guns activated at different times, methods and systems of the current disclosure are directed to computationally designing a sequence for activating subsets of air guns in a time distributed manner that minimizes the effects of air in the water surrounding the source. The sequence may be used with discrete and continuously recorded marine surveys.

Abstract: Wavefield separation methods and systems that adjust near-continuous pressure and particle motion wavefields based on distance moved along a vessel track by the sensors when the wavefields were measured are disclosed. Methods and systems correct for the motion of the receivers in towed streamer seismic data in order to obtain a wavefield with approximately stationary-receiver locations. Wavefield separation may then be applied to the wavefield with approximately stationary-receiver locations.

Abstract: A method for marine seismic surveying includes separating up-going and down-going wavefields from seismic energy emitted by at least one marine seismic energy source. The separated up-going and down-going wavefields are propagated from the at least one marine seismic energy source to at least one of a water surface and a common reference depth. One of the up-going and down-going wavefields is phase shifted 180 degrees. The propagated, phase shifted up-going and down-going wavefields are summed.

Abstract: Systems and methods to correct source responses and perform source deghosting of a pressure or particle motion wavefield recorded using near-continuous recording of seismic data along a vessel track with generalize source activation times. The methods and systems receive a near-continuously recorded seismic data and generate a near-continuous wavefield for approximately stationary-receiver locations. Time windows of different temporal lengths are applied to traces of the near-continuous wavefield in approximately stationary-receiver locations in order to compute common-receiver gathers. The common-receiver gathers are corrected source wavefield response and source ghost effects and are combined in weighted sums to generate broadband seismic data.

Abstract: A seismic streamer includes at least one elongated strength member. The seismic streamer further includes a substantially rigid sensor holder coupled to the strength member and fixed in position relative to the strength member. The streamer includes at least one particle motion sensor coupled to the sensor holder and fixed in position relative to the sensor holder.

Abstract: A method for seismic data acquisition can include near-continuously recording seismic data received from a number of seismic receivers and triggering a plurality of source elements, based upon time and not based upon position, at a predefined sequence of times relative to a start of a near-continuous recording.