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).

Embodiments relate to marine streamer cleaning. An embodiment provides a streamer cleaning apparatus comprising: a housing comprising an inlet configured to receive a streamer and an outlet configured to dispatch the streamer; and scraper lamellas coupled to the housing, wherein the scraper lamellas are arranged to form an opening to receive the streamer. Methods of cleaning a streamer and streamer cleaning systems are also provided.

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.

System for generating pressure waves for deep seismic surveys operating in an underwater environment below the surface, suitable for investigating subcrustal objectives for prospecting purposes in the search for hydrocarbons and/or minerals. The system comprises one or more autonomous underwater vehicles organized in swarms, independent and coordinated, each housing one or more autonomous acoustic sea sources with self-propelled striker pistons. This system is served by a system of supporting surface stations, for reprovisioning, recovery actions, checking the well-being of the single vehicles and swarms and maintenance. The system is capable of using both conventional and non-conventional self-charged acoustic sea seismic sources. The system is capable of replicating the effect of a conventional source operated from the surface. The seismic sea source of the non-conventional acoustic type, proposed herein, can release a high-intensity pressure wave produced by a system of two striker pistons, which does not consume air when operating as it does not disperse air or another gas in water and does not produce mass variations of the device during its functioning and allows the amplitude and duration of the sound wave emitted and characteristics of the emission spectrum, to be regulated.

Apparatus and techniques are disclosed relating to towing marine equipment. In some embodiments, a vessel tows equipment through a body of water using a towing member with an associated fairing that includes a slit, such that an axis of the slit is non-perpendicular to a portion of the towing member from which the fairing extends.

A method includes receiving, via a processor, input data based upon received seismic data, migrating, via the processor, the input data via a pre-stack depth migration technique to generate migrated input data, encoding, via the processor, the input data via an encoding function as a migration attribute to generate encoded input data having a migration function that is non-monotonic versus an attribute related to the input data, migrating, via the processor, the encoded input data via the pre-stack depth migration technique to generate migrated encoded input data, and generating an estimated common image gather based upon the migrated input data and the migrated encoded input data. The method also includes generating a seismic image utilizing the estimated common image gather, wherein the seismic image represents hydrocarbons in a subsurface region of the Earth or subsurface drilling hazards.

Marine survey. The various embodiments includes both methods and systems. At least some of the illustrative embodiments are methods including: deploying a spreader structure from vessel into a body of water, wherein the spreader structure defines a deployed width of one kilometer or more; coupling a plurality of sensor streamers to the spreader structure; and towing the plurality of sensor streamers through the water, where the horizontal separation between the sensor streamers is at least partially maintained by the spreader structure. The spreader structure provides horizontal separation sensor streamers without the use of a tensioning force applied to the spreader structure.

Systems and methods are provided for operating streamer recovery devices to retrieve seismic streamers, for example streamers that become severed from their towing vessels. The streamer recovery can be remotely activated to cause the streamer to surface where the streamer is more easily retrieved.

A sonar device intended to be towed by a surface ship and includes a tow cable and a set of at least one towed device, comprising a towed body, intended to be towed by the surface ship via the tow cable, the towed body being elongate along a longitudinal axis from a first longitudinal end of the towed body as far as a second longitudinal end of the towed body, the towed body incorporating a first linear acoustic antenna comprising a plurality of electroacoustic transducers substantially aligned along the longitudinal axis, the towed device being configured and connected to the tow cable in such a way that the towed body is able, when it is being towed and is fully submerged, to exhibit an orientation the longitudinal axis extends substantially along a vertical axis defined by the force of gravity, at least one towed body of the set of towed bodies being connected to the tow cable by a first hanger and a second hanger of substantially the same length, a first end of the first hanger and a first end of the second hanger being connected to the tow cable and a second end of the first hanger being attached to the towed body at a fixing point of the towed body which point is situated near the first longitudinal end and a second end of the second hanger being attached to the towed body at a second fixing point secured to the first fixing point and situated near the second longitudinal end.

A handling device includes a winch comprising a frame, intended to be attached to a structure of the surface vessel and a first drum capable of turning relative to the frame about a first rotation axis and an assembly comprising at least one second drum which surrounds the first drum and is capable of turning relative to the frame about a second rotation axis substantially parallel to the first rotation axis, the winch being capable of being in a decoupled state wherein the first drum and the second drum are rotationally decoupled about the first rotation axis and the second rotation axis so as to allow a traction cable to be wound around the first drum during a first winding step wherein the first drum is rotated about the first axis, the second drum being capable of being in an open state wherein the second drum has a receiving opening that a towed body is capable of passing through in order to enter the interior of the space that surrounds the first drum and that is surrounded by the second drum, the winch being capable of being in a coupled state wherein the first drum and the second drum are rotationally coupled about the second rotation axis so as to allow a flexible elongate body to be wound around the second rotation axis during a second winding step wherein the second drum is rotated about the second axis.