Marine seismic surveys, including ocean bottom surveys, utilizing marine vibrator arrays that are capable of being driven in anti-phase to produce a directional source gradient. Marine seismic surveys may include activating the vibrator array to emit a plurality of radiation patterns with at least a first radiation pattern that has a first notch at a take-off angle that is not close to vertical. Some marine seismic surveys included emitting directive wavefields from two or more simultaneous seismic source arrays, where the two or more seismic source arrays have a phase that changes from shot-to-shot to allow simultaneous source separation of the directive wavefields.

Techniques and apparatus are disclosed for performing marine seismic surveys. In some embodiments, one or more vessels are used to tow a set of streamers and two or more sources such that a first set of sources consists of all those that are disposed within a first threshold distance from the streamers, and a second set of sources consists of all those that are disposed beyond a second, greater, threshold distance from the streamers. Sources in the first set are activated more frequently than sources in the second set are activated.

Marine seismic surveys, including ocean bottom surveys, utilizing marine vibrator arrays that are capable of being driven in anti-phase to produce a directional source gradient. Marine seismic surveys may include activating the vibrator array to emit a plurality of radiation patterns with at least a first radiation pattern that has a first notch at a take-off angle that is not close to vertical. Some marine seismic surveys includes emitting directive wavefields from two or more simultaneous seismic source arrays, where the two or more seismic source arrays have a phase that changes from shot-to-shot to allow simultaneous source separation of the directive wavefields.

A method and apparatus for marine surveying. A system includes: a standard-volume source element; a large-volume source element comprising an airgun having a volume greater than 1200 cubic inches; and a long-offset survey streamer. A method includes: towing a standard-volume source element; and towing a large-volume source element; activating the large-volume source element at large shotpoint intervals; and activating the standard-volume source element at standard shotpoint intervals, wherein the large shotpoint intervals are at least twice as long as the standard shotpoint intervals. A method includes: obtaining geophysical data for a subterranean formation; and processing the geophysical data to produce an image of the subterranean formation. A method includes: obtaining a firing plan for a plurality of seismic sources, wherein: a first seismic source of the plurality comprises a large-volume source element, and a second seismic source of the plurality consists of standard-volume source elements.

Systems and methods include a method for deblending signal and noise data. A shot domain for actual sources, a receiver domain for virtual sources, and a receiver domain for actual sources are generated from blended shot data. A dictionary of signal atoms is generated. Each signal atom includes a small patch of seismic signal data gathered during a small time window using multiple neighboring traces. A dictionary of noise atoms is generated. Each noise atom includes a small patch of seismic noise data gathered during a small time window using multiple neighboring traces. A combined signal-and-noise dictionary is generated that contains the signal atoms and the noise atoms. A sparse reconstruction of receiver domain data is created from the combined signal-and-noise dictionary. The sparse reconstruction is split into deblended data and blending noise data based on atom usage to create deblended shot domain gathers for actual sources.

One embodiment includes receiving seismic data from a plurality of seismic sensors located proximate to a build section of a wellbore that is drilled into a subsurface. The seismic data is recorded for a plurality of seismic waves, at different angles, sent from a plurality of seismic sources towards the plurality of seismic sensors. Locations of the plurality of seismic sources relative to locations of the plurality of seismic sensors are such that the plurality of seismic waves are essentially planar at the plurality of seismic sensors. The subsurface is essentially homogenous proximate to the build section. For at least a portion of the plurality of seismic waves, the embodiment includes determining a slowness vector for each seismic wave, and determining a phase velocity and a phase angle. The embodiment includes determining at least one anisotropic parameter value for the build section, determining a vertical velocity value, and using these.

Techniques are disclosed relating to configuring a marine seismic survey. In some embodiments, a vessel may be coupled to one or more seismic sources and one or more seismic streamers, and a second vessel may be coupled to one or more far offset seismic sources. The near offset sources may be configured to actuate according to a shot point interval; the far offset sources may be configured to actuate according to a longer shot point interval. In some embodiments, the longer shot point interval may be a multiple of the near offset source shot point interval. Determining the first and second shot point intervals may be based in part on, for example, the wave frequencies of the far offset sources, the requirements of a full wave inversion process, or various configurational parameters of seismic surveys.

The disclosure herein generally relates to a device for use in marine seismic surveying. A displacement apparatus has a base and an actuated head. The actuated head is coupled to an actuation means comprising a shaft, a cam, and a motor. The cam is coupled to the shaft at a radial position from the center of the cam. A vacuum piston is optionally coupled to the actuation means. A variable resonance spring, such as an air spring, is coupled to the actuated head in order to tune the apparatus to operate in resonance at a range of frequencies.

Methods, systems, devices, and products for formation evaluation. Methods include automatically characterizing an acoustic reflective boundary in the earth formation by: generating a plurality of multipole acoustic signals within the borehole; generating acoustic wave data at at least one acoustic receiver on the logging tool in response to a plurality of acoustic reflections of acoustic waves from a corresponding plurality of reflection points along the boundary responsive to the multipole acoustic signals; estimating from the acoustic wave data a location in the formation for each reflection point of the plurality of reflection points, which may include performing coherence processing on at least a portion of the acoustic wave data to generate a coherence map; and identifying acoustic reflections from the coherence map; and using the location in the formation for each reflection point to estimate at least one property of the acoustic reflective boundary.

A device may include a processor that may recover the signals misallocated in the deblending process of seismic data acquired with simultaneous sources. The processor may update the primary signal estimate based at least in part on a separation operation that separates coherence signals from noise signals in an output associated with the residual determined to be remaining energy for separation. The processor may be incorporated into the iterative primary signal estimate of the deblending process or be applied towards preexisting deblending output. In response to satisfying an end condition, the processor may transmit a deblended output that includes the weak coherence signals recovered from the misallocation or error in the primary signal estimate. The processor may also transmit the deblended output for use in generating a seismic image. The seismic image may represent hydrocarbons in a subsurface region of Earth or subsurface drilling hazards.