Patent Description:
It is sought more particularly here below in this document to describe problems existing in the field of seismic data acquisition for oil prospecting industry. The invention of course is not limited to this particular field of application but is of interest for any technique that has to cope with closely related or similar issues and problems.

Marine seismic data acquisition and processing generate a profile (image) of the geophysical structure (subsurface) under the seafloor.

While this profile does not provide an accurate location for oil and gas, it suggests, to those trained in the field, the presence or absence of oil and/or gas. Thus, providing a high-resolution image of the subsurface is an ongoing process for the exploration of natural resources, including, among others, oil and/or gas.

The operations of acquiring seismic data on site conventionally use networks of seismic sensors, like accelerometers, geophones or hydrophones. We consider below the context of seismic data acquisition in a marine environment, in which the seismic sensors are hydrophones. The hydrophones are distributed along cables in order to form linear acoustic antennas (also referred to as "streamers" or "seismic streamers"). As shown in <FIG>, a seismic vessel <NUM> tows the network of seismic streamers 20a to 20e. The hydrophones are referenced <NUM> in <FIG>, which illustrates in detail the block referenced C in <FIG> (i.e. a portion of the streamer referenced 20a).

The seismic method is based on an analysis of reflected seismic waves. Thus, to collect geophysical data in a marine environment, one or more submerged seismic sources are activated in order to propagate omnidirectional seismic wave trains. The pressure wave generated by the seismic source(s) passes through the column of water and propagates through the different layers of the seabed. The reflected seismic waves (i.e. reflected acoustic signals) are then detected by the hydrophones distributed over the length of the seismic streamers. These acoustic signals are processed and retransmitted by telemetry from the seismic streamers to the operator station situated on the seismic vessel, where the processing of the raw data is carried out (in an alternative solution, the seismic acoustic signals are stored for a later processing).

During seismic surveys, it is important to precisely locate the streamers in particular for monitoring the position of the hydrophones (distributed along the seismic streamers) in order to obtain a satisfactory precision of the image of the seabed in the exploration zone; for detecting the movements of the streamers with respect to one another (the streamers are often subjected to various external natural constraints of variable magnitude, such as the wind, waves, currents); and for monitoring the navigation of streamers, in particular in a situation of bypassing an obstacle (such as an oil barge).

Control of the positions of streamers lies in the implementation of navigation control devices (also referred to as "birds") (white squares referenced <NUM> in <FIG>). They are installed at regular intervals (every <NUM> meters for example) along the seismic streamers.

Examples of birds are disclosed in <CIT>.

The function of birds is to guide the streamers between themselves. In other words, the birds <NUM> are used to control the depth as well as the lateral position of the streamers.

For this purpose, and as illustrated in <FIG>, each bird <NUM> includes a body <NUM> equipped with motorized pivoting wings <NUM> (or more generally means of mechanical moving) making it possible to modify the position of the streamers laterally between them (this is referred to a horizontal driving) and drive the streamers in immersion (this is referred to a vertical driving).

To carry out the localization of the seismic streamers (allowing a precise horizontal driving of the streamers by the birds), acoustic nodes are distributed along the streamers. These acoustic nodes are represented by hatched squares, referenced <NUM>, in <FIG>. As shown in <FIG>, some acoustic nodes <NUM> of the network are integrated in a bird <NUM> (case of <FIG>), and others are not.

Birds must be reliable and robust to keep depth and lateral control on the equipment constituted by the birds themselves and by the instrumented cables of the streamers.

As any electromechanical equipment, a bird can face internal failures that can lead to a loss of control. Furthermore, a bird and a sub-sea equipment are exposed to harsh environment, such as ice, fishing nets or debris, that can damage it, the bird being then likely to breaking down, not responding to the orders, or loosing control.

In case of loss of control or other failure of a bird, the following damages can occur. Sensors can be affected by an excessive depth of the streamer. There can be a mechanical deformation on cable and/or birds due to excessive depth, overload, excessive torsion or tangle between the cables.

Other external failures may occur such as the failure of the vessel or of the monitoring system, leading to damages of the sensors and/or birds and/or streamers. Indeed, as already said, the streamers and birds are exposed to a harsh environment, and a portion of streamer may be cut, for example by a shark, an excessive tension or an excessive twisting or by hanging to an anchor.

A known solution is to add additional equipment, commonly called "retriever", to the marine equipment, such as the bird, that is to be retrieved.

A retriever system is for example known from <CIT>. The retriever system comprises a hollow body that includes a big bag and a bottle of gas for blowing the bag when predetermined excessive depth is reached by the retriever so that the big bag exits the hollow body.

However, known retriever systems have drawbacks. In particular, it happens that the big bag be damaged when exiting the hollow body. Furthermore, known retriever systems are cumbersome causing noise on surrounding sensors. Also, it requires significant space for storage on board a vessel. Finally, it is heavy to handle during operations on a vessel deck.

Document <CIT> discloses an apparatus for inflating and releasing an inflatable buoy from a submerged vessel, having an opening through which the buoy can be released normally that is closed by a locked cover. A normally shut first valve seals off an enclosure from the exterior of the structure. The apparatus has a cartridge holder, and a piston located in a cylinder into which ignition products resulting from ignition of a cartridge in the holder pass. The piston controls a second valve located in a passage extending between a first connector for connection to a source of high-pressure gas and a second connector located in the enclosure for connection to the buoy. In response to the effect of the ignition products a mechanism causes the first valve to open to allow the enclosure to flood and also unlocks and tends to eject the cover.

Document <CIT> discloses an apparatus for locating and recovering an object disposed on the bed of a body of water, which comprises an ejectable floatation device adapted to be ejected from the body and ascend to the surface of the body of water. The device comprises a gas pressurized vessel, an ejector cylinder having an ejector piston therein engageable with an abutment on the object disposed within the cylinder. The device comprises means for delivering gas from the vessel to the cylinder during ejection of the device from the object. Means are provided for delivering gas from the vessel to a bag for inflation of the latter to ambient water pressure.

Thus, there is a need to provide retriever systems and methods for retrieving marine equipment that enable to overcome at least part of the drawbacks of the known retriever systems.

According to an embodiment, there is a retriever system for retrieving a marine equipment, according to Claim <NUM>.

According to a particular aspect, the retriever system is configured so that, when the inflating system is activated, the first inflatable element is inflated at least partially before inflation of the second inflatable element.

According to a particular aspect, the retriever system comprises a valve system that can be moved between:.

According to a particular aspect, the first inflatable element is configured to, when being inflated, move the valve system from the closed position to the opened position.

According to a particular aspect, the retriever system comprises a coupling interface that is coupled to the valve system and that partially covers the first inflatable element when the cap closes the first opening of the hollow body, to enable guiding of the movement of the valve system from the closed position to the opened position when the first inflatable element is inflating, while letting the first inflatable element exit out the hollow body through the first opening once the cap is removed.

According to a particular aspect, an area of an outer surface of the cap, that corresponds to a surface of the cap that is in contact with water when in a closing position of the cap and when the retriever system is underwater, is defined in function of:.

According to a particular aspect, the valve mechanism includes a spring and a closing element that is movable between a closing position wherein the closing element closes a gas communication path between the first inflatable element and the second inflatable element, and an opening position wherein the closing element frees the gas communication path between the first inflatable element and the second inflatable element,.

According to a particular aspect, at least part of the inflating system is inside the second inflatable element.

According to a particular aspect, the first inflatable element is configured to, when inflated and having exited the hollow body, present an elongated shape.

According to a particular aspect, the second inflatable element is configured to, when inflated and having exited the hollow body, present a spherical shape.

According to a particular aspect, the retriever system comprises an attachment system, for instance a pin or a plastic screw, configured to enable attachment of the cap to the hollow body in a position wherein the cap closes said opening, said attachment system being configured for failing in predefined conditions, for instance when a predefined force or pressure is applied to the cap.

According to another embodiment, there is an assembly comprising:.

According to a particular aspect, the marine equipment being a control device, referred to as a bird, having at least two wings for controlling a position of an instrumented cable, referred to as a streamer, adapted to be towed in water, the retriever system extends between said at least two wings of the control device.

According to a particular aspect, the marine equipment comprising a pressure detection system, the inflating system is configured to be activated in function of a pressure detected by said pressure detection system.

According to another embodiment, there is a method for retrieving a marine equipment coupled to a retriever system as discussed above, wherein the method comprises the following steps:.

The invention is described in more detail below by way of the figures that show embodiments of the invention.

The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.

Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

According to various embodiments, it is proposed a retriever system <NUM> coupled to a marine equipment.

The retriever system <NUM> can be coupled to the marine equipment <NUM> by using for instance clamping means. The retriever system <NUM> can be clamped directly on the streamer through collars, or clamped on positioning devices, or inserted inline along the streamer (dedicated inline module).

According to various embodiments, the retriever system <NUM> may be integrated in the marine equipment. In particular, the body of the retriever system may be part of the corresponding body of the marine equipment.

<FIG> illustrates an embodiment, wherein the marine equipment is a control device, referred to as a bird <NUM>. The marine equipment provided with the retriever system <NUM>, may also be a streamer or part of a streamer. Therefore, the following specification that is made with regard to a bird <NUM> also applies to other marine equipment, such as a streamer, that may be provided with the retriever system.

In the embodiment illustrated at <FIG>, the bird <NUM> has two wings <NUM>, <NUM> for controlling the position of an instrumented cable, referred to as a streamer, adapted to be towed in water. The retriever system <NUM> extends between said at least two wings <NUM>, <NUM> of the bird <NUM>. The longitudinal axis of the retriever is parallel to the longitudinal axis of the bird.

As explained hereinafter, the bird <NUM> may also include a pressure detection system <NUM>.

As illustrated in the embodiment of <FIG>, the retriever system <NUM> comprises a hollow body <NUM>. The hollow body <NUM> can be elongated. For instance, the hollow body has a general tubular or cylindrical shape. According to another embodiment, the shape may be not completely cylindrical but rather with a bulb shape.

The hollow body <NUM> has a first opening <NUM> at a first extremity. A cap <NUM> enables to close the first opening <NUM>, as shown in particular in <FIG>, while at <FIG> and <FIG> the cap <NUM> has been removed.

According to a particular aspect, the retriever system <NUM> comprises an attachment system <NUM>, for instance a pin or a plastic screw, configured to enable attachment of the cap <NUM> to the hollow body <NUM> in a position wherein the cap <NUM> closes said opening <NUM>. The attachment system <NUM> avoids non-desired ejection of the cap, in particular on board the vessel in a storage state of the retriever system <NUM>.

The attachment system <NUM> is configured for failing in predefined conditions, in particular when a predefined force or pressure is applied to the cap <NUM>.

A buoyancy assembly <NUM> is housed in the hollow body <NUM>. The buoyancy assembly <NUM> is adapted to exit the hollow body <NUM> when the cap <NUM> is removed.

A linkage system <NUM> enables to maintain the buoyancy assembly <NUM> linked to the hollow body <NUM> of the retriever system <NUM>, in particular when said buoyancy assembly <NUM> is out of said hollow body <NUM>. The linkage system <NUM> may comprise a flexible link, extensible or not, such as a rope, wire, string or cord.

According to embodiments, the buoyancy assembly <NUM> comprises a first inflatable element <NUM> and a second inflatable element <NUM>.

In the embodiments of <FIG>, the first inflatable element <NUM> is a foldable element. In particular, the first inflatable element <NUM> is folded when the buoyancy assembly <NUM> is positioned in the hollow body <NUM> without being inflated (<FIG>), and can be unfolded by being inflated (<FIG>), what causes the buoyancy assembly <NUM> to exit the hollow body <NUM> as explained hereinafter. In the embodiments of <FIG>, the second inflatable element <NUM> is also a foldable element.

According to an embodiment and as illustrated in particular at <FIG>, the first inflatable element <NUM> is configured to, when inflated and having exited the hollow body <NUM>, present an elongated shape.

For instance, the first inflatable element <NUM> has a cylindrical shape with a circular cross section. According to an embodiment and as illustrated at <FIG>, the second inflatable element <NUM> is configured to, when inflated and having exited the hollow body <NUM>, present a spherical shape.

The retriever system <NUM> comprises an inflating system <NUM> that includes an inflating generator and an activation system <NUM>, <NUM> to activate the inflating generator to provide the first inflatable element <NUM> with pressurized fluid and, at a later stage, provide the second inflatable element <NUM> with pressurized fluid, as explained hereinafter.

The inflating generator can comprise a pressurized gas bottle <NUM> or a mechanism to cause specific substance, such as powder or liquid or a solid compound, to react with another substance, and generate gas usable to inflate the first inflatable element <NUM> and the second inflatable element <NUM>.

According to embodiments, at least part of the inflating system <NUM> is inside the second inflatable element <NUM>. In particular and as illustrated in <FIG>, the inflating generator, for instance a pressurized gas bottle, extends inside the second inflatable element <NUM>.

The first inflatable element <NUM> and the second inflatable element <NUM> are coupled one to the other by a coupling system.

According to embodiments, the coupling system comprises a first annular element <NUM>, a second annular element <NUM> and between said first and second annular elements, an intermediate element <NUM>. In particular, an opening of the first inflatable element <NUM> is fixed to the first annular element <NUM>, and an opening of the second inflatable element <NUM> is fixed to the second annular element <NUM>.

First annular element <NUM>, second annular element <NUM> and intermediate element <NUM> may be connected one to the other or being parts of a same element.

According to embodiments, the coupling system, in particular the intermediate element <NUM> as illustrated at <FIG>, supports or receive the activation system <NUM>, <NUM>.

A gas communication path is provided in the coupling system to allow the gas coming from the inflating generator to pass from the first inflatable element <NUM> to the second inflatable element <NUM>.

As explained hereinafter, a valve mechanism <NUM> enables to close or open the gas communication path.

In particular, the annular opening of the first annular element <NUM> communicates with the interior of the first inflatable element <NUM> and the annular opening of the second annular element <NUM> communicates with the interior of the second inflatable element <NUM>.

According to the embodiments illustrated at <FIG>, the intermediate element <NUM> has a gas path <NUM> that communicates with the annular opening of first annular element <NUM>, and thus with the interior of first inflatable element <NUM>, and a gas path <NUM> that communicates with the annular opening of second annular element <NUM>, and thus with the interior of second inflatable element <NUM>.

Activation system <NUM>, <NUM> of the inflating system <NUM> may comprise a puncturing system <NUM> and a pyroelectric actuator <NUM> to command the puncturing system <NUM> so as to cause perforation of the inflating generator. Puncturing system <NUM> can comprise a punch or puncturing element that enables to open a gas pressurized bottle <NUM> (as an example of inflating generator) as a result of an activation of the pyroelectric actuator <NUM>.

Activation of the inflating generator provides gas to the first inflatable element <NUM> and, as explained hereafter, when a valve mechanism 54is moved in an open position, to the second inflatable element <NUM>.

The hollow body <NUM> and the buoyancy assembly <NUM> may be arranged so that, when the first inflatable element <NUM> is in a rest position, and that the inflating system <NUM> is activated, the first inflatable element <NUM> begins to be inflated by expanding inside the hollow body <NUM> (see for instance <FIG>).

The inflating system <NUM> comprises a valve mechanism <NUM> that is configured to prevent inflating of the second inflatable element <NUM> while the second inflatable element <NUM> has not exited the hollow body. In the embodiments of <FIG>, the valve mechanism <NUM> is arranged so as to open the gas communication path after the second inflatable element <NUM> has entirely exited the hollow body <NUM>.

According to another embodiment, the valve mechanism <NUM> that controls the opening or closure of the gas communication path between first and second inflatable elements, may be configured to prevent inflating of the second inflatable element while said valve mechanism <NUM>, or said gas communication path, is submitted to a pressure that is under a predefined threshold, and to enable said inflating of the second inflatable element when said pressure reaches or exceeds said predefined threshold. In that case the pressure threshold may be settled in function of the technical features of the first inflatable element and of the second inflatable element. In particular the pressure threshold associated with the valve mechanism can be settled so as to let the second inflatable element exit the hollow body before inflation of said second inflatable element. According to embodiments, the pressure threshold associated with the second inflatable element may be settled so that the second inflatable element has exited the hollow body before that the internal pressure of said second inflatable element exceeds a predefined pressure value that may compromise or interfere with a safe exit of the second inflatable element from the hollow body.

In particular, while the second inflatable element <NUM> is contained in the hollow body, the valve mechanism <NUM> closes communication between paths <NUM>, <NUM>, and thus, communication between the first inflatable element <NUM> and the second inflatable element <NUM> is closed.

According to embodiments, the valve mechanism <NUM> is positioned in the buoyancy assembly <NUM> between the first inflatable element <NUM> and the second inflatable element <NUM>.

In particular, the valve mechanism <NUM> is positioned upstream the second inflatable element <NUM> by reference with the exit direction of the buoyancy assembly <NUM> with regard to the hollow body <NUM>.

According to particular embodiment, the valve mechanism <NUM> is positioned proximate the extremity of the second inflatable element <NUM> that is opposite to the cap <NUM>.

According to embodiments, and as disclosed in <FIG>, the valve mechanism <NUM> includes a spring <NUM> and a closing element <NUM>, also referred to as a spring-loaded finger. The closing element is movable between a closing position wherein the closing element <NUM> closes the gas communication path between the first inflatable element <NUM> and the second inflatable element <NUM>, and an opening position wherein the closing element <NUM> frees the gas communication path between the first inflatable element <NUM> and the second inflatable element <NUM>.

When the buoyancy assembly <NUM> is housed in the hollow body <NUM>, the closing element <NUM> is maintained in the closing position by the internal wall of the hollow body <NUM>, thus preventing the closing element <NUM> to be moved (along a radial path of the buoyancy assembly) by the spring <NUM> in the opening position. The spring <NUM> is thus maintained in a loaded state by the hollow body <NUM> as the closing element <NUM> is maintained in the closing position by the hollow body <NUM>.

When the portion of the buoyancy assembly <NUM> that has the valve mechanism <NUM>, has exited the hollow body <NUM>, the internal wall of the hollow is no more in contact with the closing element <NUM> so that the closing element <NUM> is moved in the open position by the spring <NUM> that unloads. The gas communication path is thus free.

The valve mechanism <NUM> thus enables to control the gas communication between first inflatable element <NUM> and second inflatable element <NUM>.

When activated, inflating system <NUM> causes inflation of the first inflatable element <NUM>. Inflation of the first inflatable element <NUM> causes the buoyancy assembly <NUM> to push onto the cap <NUM> (<FIG>), what leads to the ejection of the cap (<FIG>) when the force or pressure exerted by the buoyancy assembly <NUM> on the cap <NUM> is superior to a force or pressure threshold.

According to embodiment said force or pressure threshold corresponds to a force or pressure necessary to brake the attachment system <NUM> arranged between the cap <NUM> and the hollow body <NUM>. The attachment system <NUM> can comprise a screw, such as a plastic screw cooperating with a thread arranged in the cap.

As illustrated in the embodiment of <FIG>, the pressurized gas bottle <NUM> is fixed to the coupling system so that the pressure inside the inflatable first element <NUM> generates a force that is transmitted to the pressurized gas bottle <NUM> that, as a result, pushes onto the cap <NUM>.

Once the cap <NUM> has been ejected, the buoyancy assembly <NUM> exits out of the hollow body <NUM> (<FIG>).

According to embodiments, the inflating system <NUM> is configured to start inflating the second inflatable element <NUM> when said second inflatable element <NUM> is out of the hollow body <NUM>.

According to another embodiment, the second inflatable element <NUM> may start inflating a little in the hollow body <NUM> while the cap <NUM> has not yet been ejected. Once the cap <NUM> is ejected and that the second inflatable element <NUM> has exited the hollow body <NUM>, inflation of said second inflatable element can continue outside the hollow body <NUM>.

Such conception of the retriever system <NUM> enables to cause the second inflatable element <NUM> to exit the hollow body <NUM> when the first inflatable element <NUM> is being inflated or is inflated and that the cap <NUM> is removed/expulsed, while the second inflatable element <NUM> has not yet started to inflate or has inflated just a little, thus preventing the second inflatable element <NUM> from being damaged, for instance by being cut by the edge of the opening <NUM>, when exiting the hollow body.

Activation of the inflation system <NUM> causes the first inflatable element <NUM> to inflate (<FIG>), what causes the cap <NUM> to be ejected as a result of the force applied by the buoyancy assembly <NUM> on the interior face of the cap <NUM> (<FIG>). Then, the buoyancy assembly <NUM> begins to exit the hollow body <NUM>, having the second inflatable element <NUM>, that was arranged proximate to the now expulsed cap <NUM>, exiting first the hollow body. Thanks to the positioning of the valve mechanism <NUM> between the first and second inflatable elements <NUM>, <NUM>, when the part of the buoyancy assembly that supports the valve mechanism <NUM> has exited the hollow body, the second inflatable elements has already exited the hollow body, and the valve mechanism <NUM> automatically switches on the opened position that frees the communication between the first inflatable element <NUM> and the second inflatable element <NUM> (<FIG>). The pressurized gas contained in the pressurized gas bottle <NUM> thus flows from the first inflatable element <NUM> to the second inflatable element <NUM> causing the second inflatable element <NUM> to inflate (<FIG>).

As illustrated at <FIG>, when inflated, the second inflatable element <NUM> may have a volume greater than the one of the first inflatable element <NUM>.

The retriever system comprises a valve system <NUM> that enables, when opened, to equalize pressure inside and outside the hollow body. The valve system <NUM> can be moved between a closed position wherein the valve system <NUM> closes a second opening <NUM> of the hollow body <NUM>, and an opened position wherein said second opening <NUM> of the hollow body <NUM> is opened so as to let external water enter the hollow body <NUM>.

As illustrated in the embodiments of <FIG>, the second opening <NUM> is opposite to the first opening <NUM>.

In the opened position of the valve system <NUM>, water fills the hollow-body around the buoyancy assembly <NUM>. As a result, pressure inside and outside the hollow body is equalized, what makes easier the ejection of cap <NUM>.

The first inflatable element <NUM> is configured to, when being inflated, move the valve <NUM> system from the closed position to the opened position.

The retriever system <NUM> comprises a coupling interface <NUM> that is coupled to the valve <NUM> system and that partially covers the first inflatable element <NUM> to enable guiding of the movement of the valve <NUM> system from the closed position to the opened position when the first inflatable element <NUM> is inflating. In particular, the first inflatable element <NUM> unfolds by being inflated what causes the first inflatable element <NUM> to push onto the coupling interface <NUM> that supports the valve <NUM> system.

However, the coupling interface <NUM> is designed to let the first inflatable element <NUM> exits out of the hollow body <NUM> through the first opening <NUM> once the cap <NUM> is removed. In other words, the coupling interface does not restrain movement of the buoyancy assembly in the direction of the cap.

According to embodiments, the retriever system <NUM> is configured to activate the inflating system <NUM> at a predefined depth to cause inflation of the first inflatable element <NUM>, what moves the valve <NUM> system in the opened position. The predefined depth may correspond to high depth. The predefined depth may for instance be between <NUM> and <NUM> meters, in particular when considering seismic applications.

The area of the outer surface of the cap <NUM>, that corresponds to the surface of the cap that is in contact with water when in a closing position of the cap and when the retriever system <NUM> is underwater, before opening of the valve <NUM> system, can be defined in function of (i) the area of the outer surface of the valve <NUM> system, that corresponds to the surface of the valve <NUM> system that is in contact with water when in the closed position of the valve system and when the retriever is underwater, and (ii) the water depth, or corresponding pressure, at which the inflating system <NUM> is intended to be activated.

The value of the ratio of the area of the outer surface of the cap <NUM> and the area of the outer surface of the valve <NUM> system may for instance be about <NUM>.

Contrary to some state-of-the-art retriever systems that cannot work at high depth because required pressure to release airbag equals external water pressure, the valve system <NUM> of the retriever system according to embodiments enables the retriever system to be activated at high depth.

According to a particular embodiment and as illustrated at <FIG>, the bird <NUM> comprises a pressure detection system <NUM>. The pressure detection system <NUM> is configured to detect or measure the water pressure on the marine equipment.

The inflating system <NUM> may be configured to be activated in function of a pressure detected by a pressure detection system such as said pressure detection system <NUM>. In particular, the bird <NUM> may be configured to send an activation signal (also called trigger command) to the activating system <NUM>, <NUM> of the inflating system <NUM> The pressure detection system <NUM> of the bird may communicate with the activating system <NUM>, <NUM> of the inflating system <NUM> with radio means or with connectors such as wire(s).

The activation system <NUM>, <NUM> may be configured to activate the inflating generator in predefined conditions. Predefined condition can include part or combination of the following events:.

The retriever system <NUM> can include a pressure detection system that is configured to activate the activation system <NUM>, <NUM> of the inflating system <NUM> in function of the pressure detected or measured by said pressure detection system.

In another embodiment, the activation system <NUM>, <NUM> of the inflating system <NUM> may be associated with a radio receiver included in the retriever system <NUM> and adapted to receive an activation signal from a remote transmitter, for instance positioned on board a vessel, and to control the activation system <NUM>, <NUM> based on said received activation signal. Activation system <NUM>, <NUM> of the inflating system <NUM> may also be configured to be manually controlled by an operator.

An embodiment of a method for retrieving a marine equipment that can be executed with a retriever system <NUM> according to various embodiments recited above, is now discussed. The method includes a step of activating the activation system <NUM>, <NUM>. In particular, the pyroelectric actuator <NUM> causes the puncturing system <NUM> to perforate the inflating generator (see <FIG>). Then the gas exiting the inflating generator fills and unfolds the first inflatable element <NUM>.

In case the retriever system is provided with the valve system <NUM> and corresponding coupling interface <NUM>, inflating of the first inflatable element <NUM> causes the valve <NUM> system to be moved in the open position by being pushed by the first inflatable element <NUM>. Then water enters the hollow body trough opening <NUM> and fills the hollow body around the buoyancy assembly <NUM>. Thus, pressure tends to equalize between inside and outside the hollow body <NUM> (or container) and reduce the effort needed to open (or eject) the cap <NUM>.

Inflating of the first inflatable element <NUM> make the first inflatable element <NUM> extend and thus first inflatable element <NUM> pushes the buoyancy assembly, and in particular the inflating generator, against the cap <NUM>. The cap <NUM> is then ejected from the hollow body. When the cap <NUM> is ejected, first opening <NUM> is free and the buoyancy assembly <NUM> can exit the hollow body <NUM>.

According to a preferred embodiment, expulsion or removing of the cap results from the inflating of the first inflatable element <NUM>. But according to other embodiments, the cap may be expulsed by other means independently of the inflating, for instance by a pressure mechanism coupled to that cap and that is automatically activated on a pressure threshold to cause the ejection of the cap.

Once the portion of the buoyancy assembly that has the valve mechanism <NUM>, has exited the hollow body, the valve mechanism <NUM> moves in an open position that enables to inflate the second inflatable element <NUM> that has exited the hollow body <NUM>. In particular the finger that was blocking the gas communication path between first inflatable element <NUM> and second inflatable element <NUM>, is moved by its associated spring away from the communication path so that gas can pass from the first inflatable element <NUM> to second inflatable element <NUM>.

In other words, the first and second inflatable elements are inflated in a two-time sequence.

According to embodiments, the retriever system <NUM> can be configured so that, when the inflating system <NUM> is activated, the first inflatable element <NUM> is inflated at least partially before inflation of the second inflatable element <NUM>, so as to let the second inflatable element <NUM> exit the hollow body <NUM> before inflation of said second inflatable element <NUM> or before that the internal pressure of said second inflatable element <NUM> exceeds a predefined threshold.

According to a particular embodiment that is not claimed, the retriever system comprises a hollow body and a cap as explained above. The buoyancy assembly may comprise an inflatable element, for instance only one inflatable element or a plurality, and an inflating system configured to, when activated, inflate said inflatable element. Inflating system may be as recited above. In this particular embodiment the retriever system comprises a valve system that can be moved between a closed position wherein the valve system closes a second opening of the hollow body, and an opened position wherein said second opening of the hollow body is opened so as to let external water enter the hollow body.

The inflatable element is configured to, when being inflated, move the valve system from the closed position to the opened position. The inflatable element can be a foldable bag as proposed in the other embodiments. The inflatable element may be designed so that entering of the water in the hollow body enables the inflatable element to eject the cap so as to let the inflatable element exit the hollow body while remaining linked to the hollow body.

The retriever system proposed in the above embodiment may be used to execute a method for retrieving a marine equipment coupled to a retriever system. The method comprises a step of inflating the inflatable element to move the valve system from the closed position to the opened position that lets external water enter the hollow body. Then the cap is ejected by the force exerted by the inflatable element directly or indirectly on the cap. The inflatable element exits the hollow body while remaining linked to the hollow body.

According to embodiments, the retriever system provides a compact retriever that limit acoustic and mechanical noise on seismic acquisition. Reduced dimension of the retriever system enables the retriever system to be positioned on the body of the bird, in particular between two wings of the bird. Noise on seismic sensors is minimized. Compacity of the retriever system allows its storing and easy handling on deck. Similarly, using low weight material, such as composite material, for designing the hollow body of the system retriever enable to ease its handling on deck.

The disclosed embodiments provide a retriever system and a method for retrieving a marine equipment. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

Claim 1:
A retriever system (<NUM>) for retrieving a marine equipment (<NUM>), said retriever system (<NUM>) comprising:
- a hollow body (<NUM>) having a first opening (<NUM>),
- a cap (<NUM>) adapted to close the first opening (<NUM>) of the hollow body (<NUM>) and adapted to be removed to free said first opening (<NUM>),
- a buoyancy assembly (<NUM>) housed in the hollow body (<NUM>) and adapted to exit the hollow body when the cap (<NUM>) is removed,
- a linkage system (<NUM>) to maintain the buoyancy assembly (<NUM>) linked to the hollow body of the retriever system, when said buoyancy assembly (<NUM>) is out of said hollow body (<NUM>) of the retriever system,
wherein said buoyancy assembly (<NUM>) comprises:
- a first inflatable element (<NUM>) and a second inflatable element (<NUM>),
- an inflating system (<NUM>) configured to, when activated, inflate the first inflatable element (<NUM>), so as to enable exiting of at least the second inflatable element (<NUM>) of the buoyancy assembly (<NUM>) out of the hollow body (<NUM>),
said inflating system (<NUM>) being configured to start or to continue inflating the second inflatable element (<NUM>) when said second inflatable element (<NUM>) is out of the hollow body (<NUM>),
and wherein the inflating system (<NUM>) comprises an inflating generator and an activation system (<NUM>, <NUM>) to activate the inflating generator to provide the first inflatable element (<NUM>) with gas;
characterised in that
the inflating system (<NUM>) further comprises:
a valve mechanism (<NUM>) that is configured to:
- prevent inflating of the second inflatable element (<NUM>) while said second inflatable element (<NUM>) extends inside the hollow body, and
- enable said inflating of the second inflatable element (<NUM>) after the second inflatable element (<NUM>) has exited the hollow body.