WO2017182837A1

WO2017182837A1 - A method for using a containment system and a containment system

Info

Publication number: WO2017182837A1
Application number: PCT/IB2016/000813
Authority: WO
Inventors: Van-Khoi Vu; Jean-Claude BOURGUIGNON
Original assignee: Total Sa
Priority date: 2016-04-20
Filing date: 2016-04-20
Publication date: 2017-10-26

Abstract

A method for recovering hydrocarbon fluid from a leaking device (2) using a containment system (1) comprising a dome (20), and a deflection device (40). The method comprises the steps of installing the dome and the deflection device above the leaking device.

Description

A method for using a containment system and

a containment system

FIELD OF THE INVENTION

The present invention concerns a method for using a containment system for recovering spilled oil that is leaking under water.

BACKGROUND OF THE INVENTION

The present invention concerns more precisely a method and a containment system for recovering a hydrocarbon fluid from a leaking device that is situated at the seafloor and that is leaking the hydrocarbon fluid from a well.

Recovering oil that is leaking from an under water oil device is a great problem, especially for oil device that are installed at deep sea floor.

The explosion on the "Deepwater Horizon" platform in the Gulf of Mexico demonstrated how much such a containment system is difficult to control.

One of the main problems was the formation of hydrates that clogged the used containment system.

For example, at a depth of around 1500 meters, the sea water is cold (for example around only 5°C) and at a high pressure (around 150 bars). These environment conditions may transform rapidly the sea water and hydrocarbon fluid (the light hydrocarbon components of the hydrocarbon fluid) into hydrates having a quasi-solid phase and which can fill and clogged any cavity.

Hydrates inhibitors like methanol could be injected to avoid hydrate formation. But, the needed quantity of such chemical is huge and inhibitors are also pollution for the environment .

Heating of the containment system could be used to avoid hydrate formation. But, as the volume of cavity of the containment system is great, the heating is very slow and amount of heat is too important.

OBJECTS AND SUMMARY OF THE INVENTION

One object of the present invention is to provide a method for using a containment system that avoids the formation and/or adhesion of hydrates inside the dome.

To this effect, the method for recovering hydrocarbon fluid from a leaking device that is leaking hydrocarbon fluid from a well uses a containment system that is adapted to be installed and landed at the seafloor, said seafloor corresponding to a base level of the containment system, and wherein the containment system comprises:

- a dome forming a cavity under said dome to accumulate hydrocarbon fluid coming upwardly from the leaking device, said dome comprising at least one upper output opening adapted to extract the hydrocarbon fluid for recovering, and

- a deflection device arranged to break the flow of the leaking hydrocarbon fluid that exits from the leaking device at high speed and to deviate a portion of said flow down in the direction of the base level.

The method comprises the following steps:

a) installing the deflection device above the leaking device,

b) filling the cavity of the dome with an injection fluid, and

c) installing the dome on the seafloor around the leaking device for completely surrounding and including the leaking device.

Thanks to these features of the method, the deflection device is protecting an upper portion of the volume of the cavity inside the dome against the high speed jet flow of hydrocarbon fluid that exits from the leaking device . Moreover, the deflection device deviates downwards the flow of hydrocarbon, and this prevents water below the injection fluid or hydrocarbon fluid to go upwards and to penetrate the hydrocarbon fluid phase.

Then, the upper output opening is protected from the penetration of water into hydrocarbon fluid, and is therefore protected from formation of hydrates that can clog said output.

The method can prevent or remediate hydrates formation. Therefore, the hydrocarbon fluid can be extracted from the dome by the upper output opening.

In various embodiments of the method, one and/or other of the following features may optionally be incorporated .

According to an aspect of the method, the dome is installed on the seafloor at step c) by the following sub-steps :

cl) positioning the dome laterally shifted relative to a vertical direction extending upwards from a centre of the deflection device, and in proximity of said deflection device, so as the dome is not substantially disturbed by the flow exiting from the leaking device and deviated by the deflection device,

c2) moving the dome horizontally to bring it in vertical alignment with the vertical direction and above the deflection device,

c3) moving the dome down to the seafloor.

According to an aspect of the method, before step c2), an exhaust output valve is opened on the dome for allowing the flow of hydrocarbon fluid to exit from the dome, said dome not being completely installed on the seafloor .

According to an aspect of the method, during step c2), the horizontal move is at a low speed, lower than 1 meter per minutes.

According to an aspect of the method, the dome comprises an inner surface coated with a coating that is not water wettable and that is oil wettable.

According to an aspect of the method, the deflection device is coated with a coating that is not water wettable and that is oil wettable.

According to an aspect of the method, the coating comprises grease.

According to an aspect of the method, the injection fluid is a fluid that is non-miscible with sea water and having a lower density than the sea water.

According to an aspect of the method, the injection fluid is base oil.

According to an aspect of the method, the containment system further comprises a purging valve positioned on the dome and the method comprises after step c) , the step:

d) opening the purging valve for moving the interface level between sea water and hydrocarbon fluid down to the purging valve.

Another object of the invention is to provide a variant of the above method for using a containment system wherein the dome comprises a first dome having a first volume, and a second dome having a second volume smaller than the first volume.

Then, the method comprises the following steps: a) installing the deflection device above the leaking device, installing the first dome on the seafloor around the leaking device for completely surrounding and including the leaking device,

b) filling the second volume of the second dome with an injection fluid, and

c) installing the second dome above the first dome so as the first and second volumes are in communication via a dome opening, the deflection device being positioned inside the cavity between the leaking device and the upper output opening.

According to an aspect of the method, the deflection device is positioned inside the first dome between the leaking device and the dome opening.

According to an aspect of the method, the second dome is installed on the first dome at step c) , by the following sub-steps:

cl) positioning the second dome laterally shifted relative to a vertical direction extending upwards from the centre of the first dome, and in proximity of said fist dome, so as the second dome is not substantially disturbed by the flow exiting from the first dome,

c2) moving the second dome horizontally to bring it in vertical alignment with the vertical direction and above the first dome,

c3) moving the second dome down to the first dome. According to an aspect of the method, before step c2), an exhaust output valve is opened on the second dome for allowing the flow of hydrocarbon fluid to exit from the first dome, said first dome not being completely installed on the first dome.

According to an aspect of the method, the coating comprises grease.

According to an aspect of the method, the injection fluid is base oil.

According to an aspect of the method, the containment system further comprises a purging valve positioned on the first dome and the method comprises after step c) the step:

Another object of the invention is to provide a containment system for recovering hydrocarbon fluid from a leaking device that is situated at the seafloor and that is leaking hydrocarbon fluid from a well, wherein the containment system is adapted to be landed at the seafloor corresponding to a base level of the containment system, and wherein the containment system comprises:

- a dome intended to be secured to the seafloor around the leaking device and forming a cavity under said dome, said cavity being adapted to completely surround and include the leaking device, and to accumulate hydrocarbon fluid coming upwardly from the leaking device, said dome comprising at least one upper output opening adapted to extract the hydrocarbon fluid for recovering, and

- a deflection device positioned inside the cavity between the leaking device and the upper output opening, said deflection device being arranged to break the flow of leaking hydrocarbon fluid that exits from the leaking device at high speed and to deviate a portion of said flow down in the direction of the base level.

In preferred embodiments of the containment system proposed by the invention, one and/or the other of the following features may optionally be incorporated.

According to an aspect of the containment system, the deflection device has a concave shape oriented in direction of the base level.

According to an aspect of the containment system, the deflection device has a conic shape.

According to an aspect of the containment system, the dome comprises an inner surface coated with a coating that is not water wettable and that is oil wettable.

According to an aspect of the containment system, the deflection device is coated with a coating that is not water wettable and that is oil wettable.

According to an aspect of the containment system, the coating comprises grease.

According to an aspect of the containment system, the dome comprises a first dome having a first volume adapted to receive the leaking device, and a second dome having a second volume smaller than the first volume, the second dome being situated upper the first dome, and the first and second volumes being in communication via a dome opening .

According to an aspect of the containment system, the deflection device is positioned inside the first dome between the leaking device and the dome opening.

According to an aspect of the containment system, it further comprises a convergent device positioned at the dome opening and arranged to keep away the flow of leaking hydrocarbon fluid from an inner lateral surface of the second dome.

According to an aspect of the containment system, the convergent device has a conic shape oriented in direction of the upper output opening.

According to an aspect of the containment system, the convergent device has a curved progressively convergent section .

According to an aspect of the containment system, the containment system further comprises an injection system that is arranged to inject the injection fluid inside the cavity, and wherein the injection system is only situated into or onto the second dome.

According to an aspect of the containment system, the injection fluid is a fluid that is non-miscible with sea water and having a lower density than the sea water.

According to an aspect of the containment system, the injection fluid is base oil.

According to an aspect of the containment system, it further comprises a purging valve positioned on the first dome, at a level lower than the leaking device, and preferably lower than 1 meter relative to the base level.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will be apparent from the following detailed description of at least one of its embodiments given by way of non-limiting example, with reference to the accompanying drawings. In the drawings :

- Figure 1 is a schematic view of a vertical cut of a containment system according to a first embodiment of the invention;

- Figure 2 is a schematic view of a vertical cut of a containment system according to a second embodiment of the invention;

- Figures 3a and 3b are views of the at least two steps for installing the containment system of figure 2;

- Figure 4 is a schematic view of a vertical cut of a containment system according to a third embodiment of the invention;

- Figures 5a to 5e are an exemplary of a method of installing a containment system according to the invention.

In the various figures, the same reference numbers indicate identical or similar elements. The direction Z is a vertical direction. A direction X or Y is a horizontal or lateral direction. These are indications for the understanding of the invention. MORE DETAILLED DESCRIPTION

Figure 1 is showing a first embodiment of a containment system 1 according to the invention. This containment system 1 is adapted for recovering hydrocarbon fluid from a leaking device 2 that is situated at a seafloor 5 of a deep offshore installation. The leaking device 2 is for example the well itself, a pipeline, a blow-out preventer device, a wellhead or any device connected to the wellhead. The leaking device 2 is therefore usually a large device. It may be larger than 5 m in all 3D-directions . The seafloor 5 is for example at more than 1500 meters deep below the sea surface 4. At this depth, the sea water W is cold, for example around only 5°C and at high pressure.

The hydrocarbon fluid may be liquid oil, natural gas, or a mix of them.

The leaking device 2 is leaking a hydrocarbon fluid from an undersea well 3. The hydrocarbon fluid exiting from the undersea may be rather hot, for example above 50 °C. However, the environment cold temperature and high pressure may transform the sea water W and hydrocarbon fluid HF into hydrates having a quasi-solid or solid phase. These hydrates can fill and clogged any cavity.

The containment system 1 of present invention is landed and fixed to the seafloor by any means, such as anchoring or heavy weights 29 for compensating the upward Archimedes force applied on the containment system 1 by the hydrocarbon fluid that is lighter than the sea water (lower mass density) . The seafloor corresponds in the present description to a base level of the containment system 1. The other levels are defined going upwards, in the vertical direction Z towards the sea surface 4.

The containment system 1 of figure 1 comprises at least a dome 20 intended to be secured to the seafloor around the leaking device 2 and forming a cavity 21 under said dome 20, said cavity being adapted to completely surround and include the leaking device, and to accumulate the hydrocarbon fluid coming upwardly from the leaking device, said dome comprising at least one upper output opening 22 to extract the hydrocarbon fluid for recovering.

The dome 20 is preferably fixed and/or sealed to the seafloor.

For example, the dome 20 comprises foot 20c having heavy weights for sealing and securing the dome 20 to the seafloor.

The dome 20 completely surrounds the leaking device 2. In a horizontal plane XY, the dome 20 has a closed loop shape encompassing the leaking device 2. Said shape may be for example a circle shape, a square shape or any polygonal shape.

The dome 20 has a diameter D20. This outer diameter corresponds to a maximum distance between two internal points of the dome, taken in a horizontal plane at a level near the base level BL . The diameter D20 is for example of 6 meters or more.

The dome 20 is higher than a total height of the leaking device 2. It has a height H20 of approximately 3 meters or more. It completely includes the leaking device 2 (i.e. the part above the base level. All that is under the seafloor is not taken into account as the dome is sealed to the seafloor) .

The dome 20 defines an inner dome volume, called the cavity 21. This volume is isolated (not in communication) with the environment sea water. The thermal exchange between the cold sea water and the hydrocarbon fluid is cancelled. This first effect reduces the hydrate formation .

The dome 20 is a hollow structure.

The term "dome" means in present description a general enclosure or container having a downwardly opened portion so as to be positioned above and to enclose a member. The dome has a lateral portion (like a vertical cylinder) that extends vertically from a base level to an upper level and an upper portion (like a cap) that extends horizontally from the upper end of the lateral portion so as to close the upper portion. The dome has an inner cavity with a volume adapted to receive the member. The lateral portion and/or upper portion may have some holes adapted for specific purposes (fluid exchange between the inner volume and the outside of the dome) .

The dome 20 is landed on the seafloor and contains the leaking device 2. It is a hollow structure having:

- an upper portion 24 extending in a radial direction to an outer peripheral end 24a, said radial direction being perpendicular to the vertical direction AX (equal to direction Z on the figure) , and

- a lateral portion 25 extending from the upper portion 24 downwardly between an upper end 25a and a lower end 25b, said lower end 25b comprising for example the foot 20c.

The lateral portion 25 has said diameter D20. Its inner diameter is wider than a total wide of the leaking device 2. For example, the inner diameter is of 6 meters or more .

The lateral portion 25 of the dome is downwardly opened so as to surround the leaking device 2.

The upper portion 24 of the dome 20 comprises the upper output opening 22 of the dome 20 and is adapted to be connected to a pipe 50 for extracting the hydrocarbon fluid from the containment system 1 to a recovery boat 6 at the sea surface 4, so as the hydrocarbon fluid is recovered.

In a vertical plane XZ, the upper portion 24 of the dome 20 may have a convergent shape from the lateral portion 25 up to the upper output opening 22. The dome 20 is a cover that can have advantageously an inverted funnel shape.

The hollow structure of the dome 20 forms a largely opened cavity 21 in the direction to the seafloor. It is positioned above and around the leaking device 2 so as to accumulate the light hydrocarbon fluid.

The cavity 21 accumulates hydrocarbon fluid coming upwardly from the leaking device 2, i.e. oil and/or natural gas. The hydrocarbon fluid fills the upper volume of the cavity, down to an interface level IL.

The containment system 1 can be composed of a plurality of modules, each one being installed above the other. The modules are preferably automatically secured one to the other by fastening means that automatically lock themselves when a second module is set down above a first module .

The containment system according to the invention further comprises a deflection device 40 positioned inside the cavity 21 of the dome between the leaking device 2 and the upper output opening 22, said deflection device 40 being arranged to break the flow of leaking hydrocarbon fluid that exits the leaking device at high speed and to deviate a portion of this flow down in the direction of the base level BL, near the seafloor. The speed of this deviated flow is oriented down to the seafloor, it decreases and becomes null before the flow reverses its direction to go up.

The deflection device 40 has for example a concave shape oriented in direction of the base level BL (seafloor or leaking device) . This shape may be a conic shape having its reduced end in a direction opposite to the direction of the base level BL (seafloor), or an hemispheric shape having its centre in direction of the base level (BL (seafloor or leaking device).

The upper portion of the deflection device 40 preferably comprises some holes, or any means to avoid accumulation of gas or any light element under the deflection device.

Thanks to this deflection device 40, an upper portion of the volume of the cavity 21 is protected against the high speed jet flow of hydrocarbon fluid that exits from the leaking device 2. Then, the upper output opening 22 is protected from the formation of hydrates that can clog said output. And, the hydrocarbon fluid can be extracted from the dome 20 by the upper output opening 22.

Thanks to this deflection device 40, the installation of the dome 20 above the leaking device is easier: The flow of hydrocarbon fluid does not disturb the dome 20 moving above the leaking device 2 and approaching the leaking device for being installed above or around said leaking device.

Thanks to the shape of the deflection device 40 at least a portion of the flow of the hydrocarbon fluid is deviated down to the seafloor. As water is the heaviest fluid, it is located down, near seafloor. The deviated flow acts to push water down and therefore avoids any lifting up of water inside the cavity 21. The water produced by the well and mixed with the hydrocarbon fluid is then separated and it naturally goes with sea water under the interface. Hydrates are then avoided inside the cavity, at least in upper portions of said cavity.

Additionally, the deviated flow is hot and heats the interface between hydrocarbon fluid and water. The formation of hydrates is then more efficiently prevented.

The dome 20 according to the invention may comprise an inner surface at least partially coated with a coating; said coating not being water wettable and being oil wettable. For example, the coating is or mainly comprises grease.

The "wettability" property is the preference of a solid surface to be in contact with one fluid rather than another. A drop of a preferentially wetting fluid will displace another fluid, and it will possibly completely spread over the entire surface. If a non-wetting fluid is dropped onto a surface, it will form a bead, minimizing its contact with the solid surface. Then, the wettability can be estimated by a contact angle , between the bead of the fluid at the solid surface. If the contact angle is small, the fluid forms a bead and does not wet the surface. If the contact angle is (lower than) near 180°, the fluid spreads easily onto the surface, and it does wet the surface.

In present case, the coating of dome inner surface permits to have an inner surface that is preferably oil wettable rather than water wettable. Thanks to this feature, water is not in contact with the inner surface of dome 20 and hydrates formation and/or hydrates accumulation on that inner surface is prevented.

The deflection device 40 may also be coated with a coating that is not water wettable and that is oil wettable. Preferably, this coating is or mainly comprises grease. Thanks to this coating of the deflection device, water is not in contact with the deflection device and hydrates formation and/or hydrates accumulation is prevented .

The containment system 1 according to the invention may comprise an injection system 30 that injects an injection fluid I_F into the cavity 21 when desired. The injection fluid I_F may also be injected into the cavity by any means independent the containment system 1, e.g. a remotely operated vehicle ROV that inserts and/or approaches an injection fluid pipe. The injection fluid I_F may also be introduced inside the cavity 21 near sea surface and before the dome 20 is moved down to the leaking device 2.

The injection system 30 inputs an injection fluid I_F having a separation effect and possibly a chemical effect on the fluids inside the cavity 21.

The injection system 30 can avoid the hydrates formation or the hydrates agglomeration (that may increase fluid viscosity in forming a slurry fluid) inside the cavity 21 by the chemical effect between the injection fluid I_F and the hydrates.

The injection fluid I_F is preferably a non-miscible fluid with sea water W, i.e. having a lower density than the sea water. The hydrates that may be formed inside the cavity 21 will be concentrated at the interface between sea water W and the other fluids (hydrocarbon fluid HF, injection fluid I_F, ...) because hydrates are water molecules that are arranged into a three-dimensional polyhedral around gases at a combination of low temperature and high pressure. Therefore, sea water at deep-sea locations provides the water and the cold temperature for this formation .

The injection system 30 can move the interface level IL between the sea water W and hydrocarbon fluid HF inside the cavity 21. As the hydrates may be formed or accumulated at this interface, the injection of the injection fluid I_F enables to control a vertical position of hydrates inside the cavity 21 and to possibly evacuate them out of the containment system 1, for example via one or a plurality of purging valves 65.

The injection fluid is for example base oil. Base Oil is the name given to lubrication grade oils initially produced from refining crude oil (mineral base oil) or through chemical synthesis (synthetic base oil) . Base oil is typically defined as oil with a boiling point range between 550 and 1050°F, consisting of hydrocarbons with 18 to 40 carbon atoms. This oil can be either paraffinic or naphthenic in nature depending on the chemical structure of the molecules. Base oil is the main raw material of lubricants. Base oils are produced with vacuum distillation. Lubricants are made from base oils and different kind of additives. MOL base oils meet the most- up-to-date international requirements in terms of performance properties and classes of viscosity and they can be used for motor oil and industrial oil production as well . The injection fluid preferably has a flash point higher than 80°C.

The injection fluid may be additionally heated by a fluid heater or not, for preventing to form hydrates. The fluid heater may by on a vessel at sea surface, or integrated in the injection system itself, or integrated in the upper portion of the dome 20.

Thanks to the combination of deflection device 40 positioned inside the cavity and the injection system 30 that can inject an injection fluid I_F (possibly non- miscible) , the clogging of the containment system 1 can be avoided more efficiently compared to a containment system without these devices. Additionally, the quantity of injection fluid I_F is reduced compared to a containment system without the deflection device 40. Moreover, the use of hydrate inhibitors or chemical fluid that dissolves hydrates is highly reduced and preferably cancelled. Only, a small quantity is possibly used.

The injection system 30 may comprise a plurality of output ports spread only inside the volume of cavity so as to ensure a treatment of the hydrocarbon fluid inside said volume. Then, the containment system cannot be clogged. And, the hydrocarbon fluid can be extracted via the upper output opening 22.

The injection system 30 may injects injection fluid I_F from the lateral portion or from the lateral and upper portions of the dome 20. However, the injection system 30 is preferably only on the upper portion 24 of the dome .

The injection system 30 may comprise a plurality of output ports spread near or at the upper output opening 22.

The injection fluid I_F may be stored inside a container 7 at the sea surface 4. A pump 63 extracts the injection fluid from the container 7, feeds a conduit down to the injection system 30. The container 7 may be included inside the recovery boat 6. The dome 20 according to the invention may have a height H20 higher than 5 meters and for example preferably higher than 10 meters. Thanks to this height the upper portion of the volume of cavity is more efficiently protected from hydrates formation.

The dome 20 according to the invention may have an inner volume V20 (volume of cavity 21) higher than 100 m³, and preferably higher than 250 m³. Thanks to this huge volume that can be filled with injection fluid before installation on the leaking device, the formation of hydrates is prevented more efficiently.

The dome 20 may advantageously have simultaneously a great height H20 and a huge volume V20. Both features can be combined, and the containment system 1 is then more efficient to prevent hydrates formation.

The dome 20 according to the invention may also be equipped with a convergent device 45 that is for example an opened conic shape having its opened reduced portion oriented in the direction of the upper opening 22.

The convergent device 45 may have a cross section in a vertical section plane that is curved and progressively convergent to the centre of the second volume .

This convergent device 45 is therefore a kind of annular lip located at the lower portion of the dome, i.e. at the entrance of the downwardly opened portion.

The convergent device 45 may have a cross section having a height of 30 centimetres and a width of 60 centimetres.

Firstly, such convergent device 45 can guide a flow of hydrocarbon fluid coming from underside to the centre of the volume of the dome 20. It keeps the flow away from an inner lateral surface of the dome 20.

Secondly, such convergent device 45 can have an anti-vortex effect on the flow of hydrocarbon fluid coming upwards inside the cavity of the dome. This convergent device 45 stabilizes the fluids inside the cavity. The convergent device 45 reduces the velocities of flow inside the volume of said cavity.

Thirdly, such convergent device 45 acts on the flow inside the cavity to keep it away from an inner lateral surface of the dome 20. Therefore, the convergent device 45 helps to avoid some quantity of fluid being stationary in proximity of said inner lateral surface and helps to avoid any cooling of said fluid.

The containment system 1 also advantageously comprises at least one level sensor 60 for measuring the interface level IL of the fluid interface between sea water and the hydrocarbon fluid or the injection fluid or any other fluid phase inside the dome 20.

The containment system 1 may also comprise a temperature sensor 70 for measuring a temperature of the fluid inside cavity 21. The temperature sensor 70 may provide a local temperature value, a mean temperature value of a plurality of locations inside the cavity, or a plurality of temperature values inside the cavity.

The containment system 1 may also comprise a pressure sensor for measuring a pressure of the fluid inside cavity 21.

The containment system 1 additionally comprises an output valve 62 connected to the upper output opening 22 and/or pipe 50 for outputting the recovered hydrocarbon fluid to the recovery boat 6. The output valve 62 is located in a vessel (as illustrated on figure 1) or just above the dome 20 or integrated in the dome at the upper output opening 22 (as illustrated on figure 2).

Then, a user or a control unit 61 determines or calculates a control value on the bases of a measured value of the interface level IL and/or the temperature inside the cavity and/or a pressure value, and operates the output valve on the bases of the control value for outputting hydrocarbon fluid from the cavity. The user or the control unit 61 may determine the control value to keep the interface level at a constant level inside the cavity 21.

The containment system 1 may also comprise an exhaust output valve 64 (also named a sea output valve) for example situated above the dome 20 near the upper output opening 22. The exhaust output valve 64 is adapted for opening and/or closing the cavity to the sea environment.

The exhaust output valve 64 is advantageously operated on the bases of an exhaust control value that is opposite to the control value of the output valve 62: the output valve 62 is closed when the exhaust output valve is opened, and the output valve 62 is opened when the exhaust output valve is closed.

The pipe 50 may be a two concentric tubes pipe, having an inner pipe 51 forming an inner channel, and an outer tube 52 surrounding said inner pipe 51 and forming an annular channel between the inner tube and the outer tube. The inner channel may be connected to the upper output opening 22 and used to extract the hydrocarbon fluid from the cavity 21. The annular channel may be therefore connected to the injection system 30, and used to feed it with the injection fluid from the surface. However, it is apparent that the two channel of such pipe can be connected to the dome according to the other inverse possibility without any change.

The containment system 1 may also comprise independent pipes: A first pipe 51 connected to the upper output opening 22 and used to extract the hydrocarbon fluid from the cavity 21, and a second pipe 52 connected to the injection system 30 and used to feed it with the injection fluid from the surface.

The containment system 1 may comprise other output openings and/or pipes for feeding additionally fluids, or for extracting other fluids, liquid or gases from the cavity . For example, the containment system 1 may comprise a drain valve for purging or limiting the quantity of water inside the cavity 21. Said drain valve might be positioned proximal to the base level BL (seafloor).

Moreover, the dome 20 may comprise thermal insulating material, so as to thermally insulate the cavity 21 from the cold environment of sea water. Ideally, the dome 20 may be manufactured with at least a thermally insulating material, said thermally insulating material preferably having a thermal conductivity lower than 0.1 W.m^.KT¹. The dome 20 may have an overall heat transfer coefficient lower than 2 W.m^~2.K^_1, and more preferably lower than 1 W.m^.KT¹ based on the overall internal dome wall surface.

The following thermal insulating materials may be used: synthetic material such as Polyurethane PU or polystyrene material, or a fibre textile with Polyvinyl chloride PVC coating or PU coating, or Alcryn ®. The thermal insulating material may be foam, or a gel contained inside a double wall structure.

The thermal insulation of the dome 20 passively insulates the cavity 21, while the injection system 30 actively insulates the cavity 21. Both effects prevent the formation of hydrates inside the cavity 21.

The cavity 21 is a volume storing a quantity of hydrocarbon fluid and absorbing the fluctuations of hydrocarbon fluid flows.

The cavity 21 is substantially closed, and if hydrates formation is prevented, the fluid inside the cavity is rapidly heated by the hydrocarbon fluid itself outputting from the leaking device 2.

The dome 20 comprises one or a plurality of purging valves 65 situated on the lateral portion 25 of the dome, and for example regularly spaced around the lateral portion 25. These purging valves may be at a level relative to the base level lower than 1 meter, so as the interface level IL is proximal to the base level, and preferably lower than a level of the leaking device. The purging valves may be a simple hole in the containment system wall or a biased valve or a controlled valve.

The purging valves 65 may be openings crossing through the lateral portion of the dome (two ways), or one way valves only allowing flow of fluid from inside of the dome (cavity) to the outside of the dome (environment), or a controlled valves that can be closed or opened or tuned on demand.

The purging valves 65 may be protected from outside (sea) by a chicane or any covering means. This also avoids cold sea water to enter inside the cavity (as the above one way valve) .

In use, the interface level IL is positioned at the level of said purging valve, and the volume of remaining water below said interface level IL is small compared to the dome volume V20. Figure 2 is a second embodiment of a containment system 1 according to the invention. This containment system 1 is similar to the first embodiment. It comprises the same elements as the first embodiment, and can have the same variants as disclosed above. The second embodiment of the containment system 1 differs in that the dome 20 comprises at least two parts:

- a first dome 20i having a first volume for receiving the leaking device, and

- a second dome 2Ο₂ having a second volume smaller than the first volume, said second dome being situated upper the first dome 20i, and the first and second volumes being in communication via a dome opening 26.

As represented on the figure: The first dome 20i has a diameter D20i and a height H20i. The second dome 2Ο₂ has a diameter D2O₂ (smaller than the diameter of the first dome) and a height H2O₂. As the second dome is upper the first dome, the height of the dome 20 is substantially the sum of each height, i.e. H20 = Η20ι+Η202·

The second volume may be smaller than one fourth (l/4^th) of the first volume. Preferably, the second volume is smaller than one fifth (l/5^th) of the first volume. Preferably, the second volume is smaller than one tenth (l/10^th) of the first volume.

The second volume is therefore much smaller than the first volume, and hydrates formation can be more easily prevented inside the second volume than in the first volume .

The second volume is not null. Preferably, the second volume is higher than one thirtieth (l/30^th) of the first volume, and more preferably the second volume is higher than one twentieth (l/20^th) of the first volume.

The second volume corresponds to a buffer volume comprised between 3 minutes and 10 minutes of hydrocarbon fluids, when the flow of hydrocarbon fluids from the leaking device 2 is taken into account. Preferably, the second volume corresponds to a buffer volume higher than 5 minutes of the flow of hydrocarbon fluids from the leaking device 2.

In comparison, the first volume of the first dome 20i corresponds to between 30 minutes to 60 minutes (or more) of the flow of hydrocarbon fluids from the leaking device 2.

The first dome 20i is landed on the seafloor and contains the leaking device 2. It is a hollow structure having :

The lateral portion 25 of the first dome is downwardly opened so as to surround the leaking device 2.

The upper portion 24 of the first dome 20i comprises the dome opening 26 having of small diameter compared to the dome diameter. The upper portion 24 and/or the dome opening 26 are adapted to be connected to the second dome 2 Ο 2 . The dome opening 26 has for example a diameter of 3 meters or less.

The second dome 2 Ο 2 is secured to the upper portion 24 of the first dome 20i. It is a hollow structure having a similar general shape as the first dome, i.e. having :

- an upper portion, and

- a lateral portion extending from the upper portion downwardly between an upper end and a lower end.

The lateral portion of the second dome 2 Ο 2 has a diameter wider than the dome opening 26. For example, the diameter of the lateral portion is higher than 3 meters, and preferably lower than 5 meters.

The second dome 2 Ο 2 comprises downwardly a bottom opening having a width equal to the dome opening 26 or wider than said dome opening. When the second dome 2 Ο 2 is secured above the first dome 20i, the bottom opening comes substantially into coincidence with the dome opening 26, and the second volume is in communication with the first volume via said dome opening 26 (and reciprocally) . The hydrocarbon fluid that exits from the leaking device 2 is going naturally upwardly from the first volume to the second volume via said dome opening 26.

The first and second domes 20ι, 2 Ο 2 may comprise fastening means so as the second dome 2 Ο 2 is automatically secured to the first dome 20i as soon as the second dome is set down on the first dome. Any known mechanical means can be used for said fastening means, such as pins, spring loaded pins, etc... The fastening means are locked automatically by the setting down of the second dome above the first dome. They might be unlocked manually or remotely or via any actuation mean.

The upper portion of the second dome 2Ο₂ comprises the upper output opening 22 of the dome 20 and is adapted to be connected to a pipe 50 for extracting the hydrocarbon fluid from the containment system 1 to a recovery boat 6 at the sea surface 4, so as the hydrocarbon fluid is recovered .

In a vertical plane XZ, the upper portion 24 of the first dome 20i may have a convergent shape from the lateral portion 25 up to the dome opening 26. The dome 20 is a cover that can have advantageously an inverted funnel shape .

The hollow structure of the dome 20 (first and second domes 20ι, 2Ο₂) forms a largely opened cavity 21 in the direction to the seafloor. It is positioned above and around the leaking device 2 so as to accumulate the light hydrocarbon fluid.

The containment system 1 according to the second embodiment of the invention then comprises at least a deflection device 40 positioned inside the first dome 20i between the leaking device 2 and the dome opening 26. It breaks the flow of leaking hydrocarbon fluid that exits and deviates at least a portion of said flow down in the direction of the base level BL, near the seafloor.

The deflection device 40 can have the same shapes as disclosed for the first embodiment. Thanks to this deflection device 40, the second volume of the second dome 2Ο₂ is protected against the high speed jet flow of hydrocarbon fluid that exits from the leaking device 2. And, the upper output opening 22 is protected from the formation of hydrates.

The containment system 1 may further comprise an injection device 30 that injects an injection fluid I_F into the cavity 21. This injection device is advantageously located inside the second dome 2Ο₂. It generates the same effect as disclosed above. The injection fluid I_F can be also identical.

Additionally, the injection system 30 is preferably only situated into or onto the second dome 2Ο₂. The injection system 30 is arranged to input an injection fluid I_F into the cavity 21 of the dome, but firstly into the second volume of the second dome 2Ο₂. Then, if the second dome 2Ο₂ is full of injection fluid I_F, it can continue to injects so as to progressively fill also the first dome 20i and to move the interface level down to the seafloor.

The first dome 20i is preferably thermally insulated so as to keep its huge first volume to a highest temperature as possible, said first volume being heated by the heat of the hydrocarbon fluid outputting from the leaking device 2.

The dome 20 according to the second embodiment may have a height H20 being higher than limits defined in the first embodiment, so as to behave similarly. The dome 20 according to the invention may have an inner volume V20 (volume of cavity 21) higher than the limits defined in the first embodiment, so as to behave similarly. The dome 20 may advantageously have simultaneously a great height H20 and a huge volume V20.

The containment system 1 according to the second embodiment of figure 2 is installed in an at least two steps method represented on figures 3a and 3b. The defection device 40 and the first dome 20i are firstly installed on the seafloor so as to surround the leaking device 2 as represented on figure 3a. They are installed simultaneously, or the deflection device is installed before the first dome 20i. Then, the second dome 20i is installed above the first dome 201 as represented on figure 3b. The method will be more detailed explained later . Figure 4 is a third embodiment of a containment system 1 according to the invention. This containment system 1 is very similar to the one of the first embodiment. It comprises the same elements, and can have the same variants as disclosed above. The containment system 1 of the third embodiment differs in that it further comprises a wall 41, for example having a substantially general cylindrical shape that is installed on the seafloor. Then after, the dome 20 similar or identical to the one of first embodiment is installed above the wall 41 and secured to it.

The wall 41 may be installed together or independently to the deflection device 40 (i.e. after).

The wall comprises means for fixing and/or stabilizing it on the seafloor, such as anchoring or heavy weights 29. The wall 41 advantageously comprises the purging valves 65 so as the interface level IL is proximal to the seafloor and preferably below a level of the leaking device 2.

The dome 20 according to the second embodiment may have a height H20 being higher than limits defined in the first embodiment, so as to behave similarly. The dome 20 according to the invention may have an inner volume V20 (volume of cavity 21) higher than the limits defined in the first embodiment, so as to behave similarly. The dome 20 may advantageously have simultaneously a great height H20 and a huge volume V20. The method for using or installing the containment system 1 according to the invention is now explained with the figures 5a to 5e , this explanation being based on the second embodiment of the containment system as illustrated on figure 2, but a similar explanation can be given on the bases of the first or third embodiment of the containment system as illustrated on figures 1, 3.

At figure 5a , a first dome 20i is landed and secured to the seafloor 5. The first dome 20i then may be sealed around the leaking device 2. The leaking device 2 is then completely inside the first volume of the first

The deflection device 40 is also positioned inside the first volume between the leaking device 2 and the dome opening 26. The deflection device 40 is possibility installed before the first dome 20i or simultaneously with said first dome 20i or after said first dome 20i.

Hydrocarbon fluid leaking from the leaking device 2 is then deviated downwards before it is flowing upwards inside the first volume and exiting from the first volume via the dome opening 26.

At this step, the second dome 2 Ο 2 is for example positioned above the first dome 20i, but laterally shifted relative to the vertical direction AX that extends from the centre of the first dome 20i. The second dome 2 Ο 2 is not disturbed by the flow of hydrocarbon fluid exiting from the first dome 20i previously installed. The second dome 2 Ο 2 is then in proximity of said first dome.

The second dome 2 Ο 2 can be filled with the injection fluid I_F in that position by any means (injection device or independent means) . The second dome 2 Ο 2 is at least partially filled with the injection fluid I_F. For example, the second volume of the second dome 2 Ο 2 is filled of at least 80% of its entire volume, and preferably of at least 90% of its entire volume. Advantageously, the second volume of the second dome 2 Ο 2 is completely filled with said injection fluid IF .

At figure 5b , the second dome 2 0₂ is horizontally moved (arrow Al ) so as to bring it in vertical alignment with the vertical direction AX. The second dome 2 Ο 2 is then just above the first dome 20i but not connected to the first dome 20i. The flow of hydrocarbon fluid is partially going inside the lower portion of the second volume of said second dome 2 0₂ .

The horizontal move is at a low speed, for example lower than 1 meter per minutes. The injection fluid I_F is then kept stable inside the second volume of the second dome 2 Ο 2 .

Thanks to the deflection device 40 inside the first dome 20i, the flow of hydrocarbon fluid upwardly exiting from the first dome 20i is not a jet flow, and do not have a high speed. The flow velocity of hydrocarbon fluid has been reduced inside the first dome by the deflection device 40 before exiting the first dome 20i.

Therefore, the injection fluid I_F inside the second dome 2 Ο 2 is also kept stable inside the second volume of the second dome 2 Ο 2 , and is not flushed out of said second dome 2 Ο 2 by the flow of hydrocarbon fluid going upwards in the direction of the second dome. And, hydrates formation is avoided inside said second dome.

An exhaust output valve 64 situated above the second dome 2 Ο 2 is possibly opened for evacuating determined quantity of fluid from the second volume so as to help keeping stable the second dome 2 Ο 2 and the fluid inside the second dome 2 Ο 2 . A quantity of infection fluid I_F may be continuously injected inside the second dome 2 Ο 2 to keep a great proportion of injection fluid I_F inside said second dome 2 Ο 2 . The flow of fluid exiting from the exhaust output valve 64 and the flow of injection fluid I_F entering from the injection system 30 may be controlled, for example by the control unit 61. At figure 5c, the second dome 2 0₂ is then moved down to the first dome 20i (arrow A2 ) for being installed and secured on the first dome so as the first and second volumes are put into communication together via the dome opening 26. The cavity 21 is gathering the first and second volumes, and the cavity 21 is then substantially closed.

The exhaust output valve 64 situated above the second dome 2Ο₂ is still open for evacuating a quantity of hydrocarbon fluid.

At least one of the purging valves 65 is opened.

The quantity of hydrocarbon fluid inside the cavity 21 is increasing and therefore sea water W that is present at low level inside the cavity 21 is evacuated through the purging valves 65.

The injection system 30 may also additionally inject injection fluid I_F inside the cavity 21. Sea water is then more efficiently evacuated through the purging valves 65.

Both effects tend to evacuate sea water W out of the cavity via the purging valve (s) 65 at a low level near the seafloor. The interface level IL corresponding to the interface between sea water and hydrocarbon fluid is therefore moved down to the level of the purging valve 65. Moreover, the possibly formed hydrates that are concentrated at this interface level IL, are also pushed down to the purging valve (s) 65. These hydrates can then be evacuated with sea water or remediated by the increase of temperature. The hydrates are therefore away from the upper output opening 22, and the method of the invention avoids the clogging of the containment system 1.

As represented on figure 5d, the flow of leaking hydrocarbon fluid HF and possibly of injection fluid I_F being greater than the flow of fluid exiting the cavity 21 through the exhaust output valve 64, the interface between sea water W and the hydrocarbon fluid HF has moved down to the level of the purging valve 65, and sea water has been evacuated through the purging valve 65.

The hydrates formation is also more efficiently prevented as there is less water inside the cavity 21 and as the hydrocarbon fluid HF is itself progressively heating the cavity 21.

If the injection system 30 injects the injection fluid I_F inside the cavity 21 for moving more rapidly the interface down to the level of the purging valve 65, the sea water W is evacuated more rapidly, and the hydrates formation is more easily and efficiently prevented.

At this step, the deflection device 40 deviate the flow of hydrocarbon fluid HF down to the interface between water and hydrocarbon fluid (or mix of hydrocarbon fluid and injection fluid) . This deviated flow downwards prevents water to go upwards inside the cavity 21, and avoids hydrates that may be formed at the interface to go upwards.

The interface with water is then also warmed by the newest hydrocarbon fluid deviated by the deflection device 40, and hydrates formation is prevented. Additionally, water from well is separated from hydrocarbon fluid and goes with sea water under the interface.

At figure 5e, the output valve 62 is then opened, and hydrocarbon fluid is recovered via upper output opening 22 and the pipe 50.

Depending on the flow of hydrocarbon fluid HF leaking from the leaking device 2 and the flow of hydrocarbon fluid recovered, the exhaust output valves 64 and the purging valves 65 can be controlled, e.g. by the control unit 61, to a reduced flow or can be completely closed.

Therefore, the containment system 1 according to the invention comprises:

- a dome 20 forming a cavity 21 under said dome to accumulate hydrocarbon fluid coming upwardly from the leaking device, said dome comprising at least one upper output opening 22 adapted to extract the hydrocarbon fluid for recovering, and

- a deflection device 40 arranged to break the flow of the leaking hydrocarbon fluid that exits from the leaking device 2 at high speed and to deviate a portion of said flow down to the base level (in the direction of the base level BL) .

The method according to the invention for using or installing the containment system 1 comprises the following successive steps:

a) installing the deflection device 40 above the leaking device,

b) filling the cavity of the dome 20 with the injection fluid by the injection system 30 or by any means, and

c) installing the dome 20 on the seafloor around the leaking device for completely surrounding and including the leaking device, and then eventually securing the dome 20 to the seafloor by any means.

The above filling at step b) may be a partially filling or a completely filling at previously explained.

Thanks to the above method, the flow of leaking hydrocarbon fluid is not flushing the injection fluid inside the volume of the dome. Water is prevented going up inside the cavity. The hydrates that may be formed inside the cavity are not clogging the containment system.

The injection system 30 can move rapidly the possibly hydrates down to the base level BL where they are evacuated or remediated.

The above step c) may comprise the following sub-steps :

cl) positioning the dome 20 laterally shifted relative to a vertical direction extending upwards from a centre of the deflection device, and in proximity of said deflection device, so as the dome is not substantially disturbed by the flow exiting from the leaking device and deviated by the deflection device,

c2) moving the dome 20 horizontally to bring it in vertical alignment with the vertical direction and above the deflection device,

c3) moving the dome down to the seafloor.

In the second embodiment of the containment system 1, the dome 20 may further comprise a first dome 20i having a first volume, and a second dome 2 Ο 2 having a second volume smaller than the first volume. In that case, the method then comprises the following steps:

a) installing the deflection device 40 above the leaking device 2, and installing the first dome 20i on the seafloor around the leaking device 2 for completely surrounding and including the leaking device 2, and eventually securing the first dome to the seafloor,

b) filling the second volume of the second dome 2 Ο 2 with the injection fluid by the injection system 30 or by any means, and

c) installing the second dome 2 Ο 2 above the first dome 20i so as the first and second volumes are in communication via a dome opening 26, the deflection device 40 being then positioned inside the cavity 21 between the leaking device 2 and the upper output opening 22.

The sub-steps of step a) may be in any successive order or simultaneous.

Thanks to the above method, the flow of leaking hydrocarbon fluid is not flushing the injection fluid inside the second volume of the second dome 2 Ο 2 .Water is prevented going up inside the cavity. The hydrates that may be formed inside the cavity are not clogging the containment system 1.

The time delay for installing the second dome 2 Ο 2 above the first dome 20i is shorter than the time delay for installing the first dome on the seafloor. The risk of hydrates formation is then reduced.

The injection system 30 can move the possibly hydrates rapidly down to the base level BL where they are evacuated or remediated.

In operation, the deflection device 40 deviates the hot hydrocarbon fluid down the water, and hydrates formation is continuously prevented.

Moreover, the step c) may comprise the following sub-steps :

cl) positioning the second dome 2Ο₂ laterally shifted relative to a vertical direction AX extending upwards from the centre of the first dome, and in proximity of said fist dome, so as the second dome is not substantially disturbed by the flow exiting from the first c2) moving the second dome 2Ο₂ horizontally to bring it in vertical alignment with the vertical direction AX and above the first dome,

c3) moving the second dome 2Ο₂ down to the first

In all embodiments of the containment system 1, the containment system 1 may further comprise a purging valve 65 positioned on the dome 20 and the method comprises after step c) , the step:

d) opening the purging valve 65 for moving the interface level IL between sea water and hydrocarbon fluid down to the purging valve.

Then, the injection system 30 may additionally injects a quantity of injection fluid IF inside the cavity during step d) to accelerate the moving of the interface level IL, preferably down to a purging valve 65.

Then, the following steps may be also executed for preventing more efficiently the hydrates formation:

e) waiting for increase of a temperature inside the cavity above a predetermined temperature value, and f) beginning the extraction of hydrocarbon from the containment system.

Claims

1. A method for recovering hydrocarbon fluid from a leaking device (2) that is situated at the seafloor and that is leaking hydrocarbon fluid from a well, said method using a containment system (1) adapted to be installed and landed at the seafloor, said seafloor corresponding to a base level of the containment system, and

wherein the containment system (1) comprises:

- a dome (20) forming a cavity (21) under said dome to accumulate hydrocarbon fluid coming upwardly from the leaking device, said dome comprising at least one upper output opening (22) adapted to extract the hydrocarbon fluid for recovering, and

- a deflection device (40) arranged to break the flow of the leaking hydrocarbon fluid that exits from the leaking device at high speed and to deviate a portion of said flow down in the direction of the base level,

wherein the method comprises the following steps:

a) installing the deflection device (40) above the leaking device,

b) filling the cavity of the dome (20) with an injection fluid (I_F) , and

c) installing the dome (20) on the seafloor around the leaking device for completely surrounding and including the leaking device.

2. The method according to claim 1, wherein the dome (20) is installed on the seafloor at step c) by the following sub-steps:

cl) positioning the dome (20) laterally shifted relative to a vertical direction extending upwards from a centre of the deflection device, and in proximity of said deflection device, so as the dome is not substantially disturbed by the flow exiting from the leaking device and deviated by the deflection device, c2) moving the dome (20) horizontally to bring it in vertical alignment with the vertical direction and above the deflection device,

c3) moving the dome down to the seafloor.

3. The method according to claim 2, wherein, before step c2), an exhaust output valve (64) is opened on the dome (20) for allowing the flow of hydrocarbon fluid to exit from the dome, said dome not being completely installed on the seafloor.

4. The method according to claim 1, wherein the dome (20) comprises an inner surface coated with a coating that is not water wettable and that is oil wettable.

5. The method according to claim 1 or claim 4, wherein the deflection device (40) is coated with a coating that is not water wettable and that is oil wettable.

6. The method according to claim 4 or claim 5, wherein the coating comprises grease.

7. The method according to claim 1, wherein the injection fluid (I_F) is a fluid that is non-miscible with sea water and having a lower density than the sea water.

8. The method according to claim 7, wherein the injection fluid is base oil.

9. The method according to claim 8, wherein the containment system further comprises a purging valve (65) positioned on the dome (20i) and the method comprises after step c) , the step:

d) opening the purging valve (65) for moving the interface level (IL) between sea water and hydrocarbon fluid down to the purging valve.

10. A method for recovering hydrocarbon fluid from a leaking device (2) that is situated at the seafloor and that is leaking hydrocarbon fluid from a well, said method using a containment system (1) adapted to be installed and landed at the seafloor, said seafloor corresponding to a base level of the containment system, and

wherein the containment system (1) comprises:

- a dome (20) forming a cavity (21) under said dome to accumulate hydrocarbon fluid coming upwardly from the leaking device, said dome comprising at least one upper output opening (22) adapted to extract the hydrocarbon fluid for recovering, the dome (20) comprising a first dome (20i) having a first volume, and a second dome (2Ο₂) having a second volume smaller than the first volume, and

wherein the method comprises the following steps:

a) installing the deflection device (40) above the leaking device, installing the first dome (20i) on the seafloor around the leaking device for completely surrounding and including the leaking device, b) filling the second volume of the second dome (2Ο₂) with an injection fluid (I_F) , and

c) installing the second dome (2Ο₂) above the first dome (20i) so as the first and second volumes are in communication via a dome opening (26), the deflection device (40) being positioned inside the cavity between the leaking device and the upper output opening.

11. The method according to claim 10, wherein the deflection device (40) is positioned inside the first dome (20i) between the leaking device and the dome opening ( 26 ) .

12. The method according to claim 10, wherein the second dome ( 2 Ο 2 ) is installed on the first dome (20i) at step c) , by the following sub-steps:

cl) positioning the second dome ( 2 Ο 2 ) laterally shifted relative to a vertical direction (AX) extending upwards from the centre of the first dome, and in proximity of said fist dome, so as the second dome is not substantially disturbed by the flow exiting from the first

c2) moving the second dome ( 2 Ο 2 ) horizontally to bring it in vertical alignment with the vertical direction (AX) and above the first dome,

c3) moving the second dome ( 2 Ο 2 ) down to the first

13. The method according to claim 12, wherein, before step c2), an exhaust output valve (64) is opened on the second dome ( 2 Ο 2 ) for allowing the flow of hydrocarbon fluid to exit from the first dome, said first dome not being completely installed on the first dome.

14. The method according to claim 12, wherein, during step c2), the horizontal move is at a low speed, lower than 1 meter per minutes.

15. The method according to claim 10, wherein the dome (20) comprise an inner surface coated with a coating that is not water wettable and that is oil wettable.

16. The method according to claim 10 or claim 15, wherein the deflection device (40) is coated with a coating that is not water wettable and that is oil wettable.

17. The method according to claim 15 or claim 16, wherein the coating comprises grease.

18. The method according to claim 10, wherein the injection fluid (I_F) is a fluid that is non-miscible with sea water and having a lower density than the sea water.

19. The method according to claim 18, wherein the injection fluid is base oil.

20. The method according to claim 10, wherein the containment system further comprises a purging valve (65) positioned on the first dome (20i) and the method comprises after step c) the step:

21. A containment system (1) for recovering hydrocarbon fluid from a leaking device that is situated at the seafloor and that is leaking hydrocarbon fluid from a well, wherein the containment system (1) is adapted to be landed at the seafloor corresponding to a base level of the containment system, and wherein the containment system comprises :

- a dome (20) intended to be secured to the seafloor around the leaking device and forming a cavity (21) under said dome, said cavity being adapted to completely surround and include the leaking device, and to accumulate hydrocarbon fluid coming upwardly from the leaking device, said dome comprising at least one upper output opening (22) adapted to extract the hydrocarbon fluid for recovering, and

- a deflection device (40) positioned inside the cavity between the leaking device and the upper output opening, said deflection device being arranged to break the flow of leaking hydrocarbon fluid that exits from the leaking device at high speed and to deviate a portion of said flow down in the direction of the base level.

22. The containment system according to claim 21, wherein the deflection device has a concave shape oriented in direction of the base level.

23. The containment system according to claim 22, wherein the deflection device has a conic shape.

24. The containment system according to claim 21, wherein the dome (20) comprises an inner surface coated with a coating that is not water wettable and that is oil wettable .

25. The containment system according to claim 21 or claim 24, wherein the deflection device (40) is coated with a coating that is not water wettable and that is oil wettable .

26. The containment system according to claim 24 or claim 25, wherein the coating comprises grease.

27. The containment system according to claim 21, wherein the dome (20) comprises a first dome (20i) having a first volume adapted to receive the leaking device, and a second dome (2Ο₂) having a second volume smaller than the first volume, the second dome (2Ο₂) being situated upper the first dome (20i), and the first and second volumes being in communication via a dome opening (26) .

28. The containment system according to claim 27, wherein the deflection device is positioned inside the first dome (20i) between the leaking device and the dome opening ( 26 ) .

29. The containment system according to claim 27 or claim 28, further comprising convergent device (45) positioned at the dome opening (26) and arranged to keep away the flow of leaking hydrocarbon fluid from an inner lateral surface of the second dome (2Ο2).

30. The containment system according to claim 29, wherein the convergent device (45) has a conic shape oriented in direction of the upper output opening (22).

31. The containment system according to claim 29, wherein the convergent device (45) has a curved progressively convergent section.

32. The containment system according to claim 27, further comprising an injection system (30) that is arranged to inject an injection fluid (I_F) inside the cavity, and wherein the injection system (30) is only situated into or onto the second dome (2Ο2).

33. The containment system according claim 21, wherein the injection fluid (I_F) is a fluid that is non-miscible with sea water and having a lower density than the sea water .

34. The containment system according to claim 32, wherein the injection fluid is base oil.

35. The containment system according to claim 27, further comprising a purging valve (65) positioned on the first dome (20i), at a level lower than the leaking device, and preferably lower than 1 meter relative to the base level .