A gradient sensor device includes a support structure providing a surface, and at least three particle motion sensors coupled with and/or arranged on the support structure to measure translational data in a first direction. The particle motion sensors have an arrangement that enables calculation of a spatial gradient of the translational data in a second direction different from the first direction.

An autonomous underwater vehicle (AUV) for guiding other AUVs during a marine seismic survey. The guiding AUV includes a housing; a propulsion system located inside the housing; and an acoustic positioning system attached to an outside the housing. The acoustic positioning system emits at least three chirps from three different locations.

Systems and methods for attenuating vibrations in marine seismic equipment involve a vessel towing a seismic streamer having a plurality of seismic receivers. The seismic streamer is connected to the vessel by a front-end and a damper is coupled to the front-end. A vibration on the front-end is detected and a damper response to the detected vibration on the front-end is then determined. The damper is actively adjusted based on the damper response. The active adjustment dampens vibrations in an axial direction along a lead-in of the front-end and/or vibrations in a direction transverse to an axial direction of the lead-in.

The invention relates to a method for seismic survey by autonomous seismic nodes (1) at a sea floor (2), comprising: —attaching the seismic nodes (1) to a rope (3); —loading the rope (3) with the seismic nodes into a node deployer (4); —lowering the node deployer (4) into the sea (5); —towing the node deployer (4) above the sea floor (2); —deploying the rope (3) with the seismic nodes (1) at the sea floor (2); —collecting seismic data by the seismic nodes (1); —retrieving the rope (3) with the seismic nodes (1) from the sea floor (2), and —unloading seismic data from the seismic nodes (1). The invention also relates to a node deployer (4) for deploying a rope (3) with seismic nodes (1) at the sea floor (2), comprising a magazine (7) for the rope (3) with the seismic nodes (1).

A survey plan is designed and potentially adjusted so that seismic data acquired during the survey include inline and cross-line seismic data irregularities suitable for compressive sensing reconstruction. At least one of the inline and cross-line irregularities is dynamic and may be due to source, vessel(s) and/or streamer steering.

This disclosure describes processes and systems for generating a high-resolution velocity model of a subterranean formation from recorded seismic data gathers obtained in a marine seismic survey of the subterranean formation. A velocity model is computed by iterative FWI using reflections, resolving the velocity field of deep subterranean targets without requiring ultralong offsets. The processes and systems use of an impedance sensitivity kernel to characterize reflections in a modeled wavefield, and then use the reflections to compute a velocity sensitivity kernel that is used to produce low-wavenumber updates to the velocity model. The iterative process is applied in a cascade such that position of reflectors and background velocity are simultaneously updated. Once the low-wavenumber components of the velocity model are updated, the velocity model is used as an input of conventional FWI to introduce missing velocity components (i.e., high-wavenumber) to increase the resolution of the velocity model.

An apparatus for acquiring survey data including streamer equipment comprising a lead-in cable; and a geophysical streamer with a plurality of geophysical sensors distributed along the geophysical streamer, including a forward geophysical sensor; a depressor coupled to the streamer equipment in front of the forward geophysical sensor; a variable tension control device coupled at a back end of the geophysical streamer; and a plurality of tension control system sensors. A method for acquiring survey data including obtaining data from tension control system sensors of a geophysical streamer system; identifying an adjustment to be made to one or more tension control factors of the geophysical streamer system to reduce or control vibrational behavior of streamer equipment of the geophysical streamer system making the adjustment to the one or more tension control factors; and acquiring survey data with the geophysical streamer system.

System and method for enriching a bandwidth of seismic data related to a subsurface of a body of water. The system includes streamers and sources that are towed at alternating depths during consecutive and/or adjacent line of sails or during the same line of sail.

There is a method for acquiring seismic data over a survey area. The method includes deploying streamer and source vessels to acquire seismic data along a survey line; performing one pass with the streamer and source vessels along the survey line for collecting wide azimuth (WAZ) data; and performing another pass with the streamer and source vessels along the survey line for collecting narrow azimuth (NAZ) data.

A subaqueous underground survey system using a reflection seismic survey method includes: multiple sound sources 1 for generating sound waves in the water; a controller 2 for controlling phases of the sound waves; a geophone 3 for receiving reflected waves of the sound waves; and an observation ship 4 equipped with the sound sources 1, wherein the controller 2 controls phases of the sound sources 1 so that the sound waves generated from the respective sound sources 1 have a phase difference at a water bottom surface B, thereby controlling generation of shear waves to propagate into the ground.