OA17373A

OA17373A - A containment system and a method for using said containment system.

Info

Publication number: OA17373A
Application number: OA1201500110
Authority: OA
Inventors: Van-Khoi Vu; Jean-Claude Bourguignon
Original assignee: Total S.A.
Priority date: 2012-10-05
Filing date: 2012-12-14
Publication date: 2016-09-21

Abstract

A containment system (1) for recovering hydrocarbon fluid from a leaking device (2) comprising a wall (10) extending from a base level (BL) to a first level (L1) for surrounding the leaking device, and a dome (20) situated above the wall and forming a cavity (21) for accumulating hydrocarbon fluid. The dome comprises an upper output opening (22) for extracting the hydrocarbon fluid. The containment system further comprises a lower output opening (2 3) extending up to a dome level (DL). The wall (10) and the dome (20) are independent members so as the wall can be landed on the seafloor before the dome is installed.

Description

The présent invention concerns a containment System for recovering spilled oil that is leaking under water.

BACKGROUND OF THE INVENTION

The présent invention concerns more precisely 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. These environment conditions may transform the sea water and hydrocarbon fluid into hydrates having a quasisolid 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.

OBJECTS AND SUMMARY OF THE INVENTION

One object of the présent invention is to provide a containment System that avoids the formation of hydrates inside the dôme.

To this effect, the containment System of présent invention is adapted to be landed at the seafloor corresponding to a base level of the containment system. It comprises at least:

- a wall extending from the base level to a first level so as to completely surround the leaking device, said wall being substantially sealed to the seafloor around said leaking device, and

- a dôme situated above the wall and forming a cavity under said dôme, said cavity being adapted for accumulating hydrocarbon fluid coming upwardly from the leaking device, said dôme comprising at least one output opening adapted to extract the hydrocarbon fluid for recovering.

The containment System further comprises a lower output opening extending up to a dôme level.

The wall and the dôme of the containment system according to the invention are independent members so as the wall can be landed on the seafloor before the dôme is installed.

Thanks to these features, the wall séparâtes the fluid around the leaking device to the cold sea water. The fluids contained inside the wall volume around the leaking device is heated by the hydrocarbon fluid outputting from the leaking device, and is not cooled by the sea water.

Usually, cold water from seafloor is sucked up by the hydrocarbon fluid outputting from the leaking device at a high speed. This phenomenon generates a high convection movement between the cold sea water and the outputting hydrocarbon fluid. The wall of présent invention cancels the horizontal movement of sea water at seafloor around the leaking device, and therefore cancels the sucking of cold water from sea by the outputting of hydrocarbon fluid from the leaking device. The wall therefore cancels the thermal convection exchange between the cold sea water and the hydrocarbon fluid.

Additionally, the wall cancels cold sea water to be sucked inside the dôme cavity. The hydrocarbon fluid— accumulated below the dôme is therefore not cooled by sea water.

As, the wall can be easily installed around the leaking device before the dôme, the sea water sucking can be cancelled before installing the dôme above the wall. Thanks to the features of the proposed containment System, it can be easily installed around and above the leaking device without risking any hydraulic convection perturbations that may move the dôme during installation.

As, the thermal exchanges between the sea water and the hydrocarbon fluid are then dramatically reduced by the containment System of présent invention, and the hydrate formation is therefore prevented inside the cavity of the dôme.

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

According to an aspect of the containment System, the dôme further comprises a first injection device that inputs a first warm fluid into the cavity.

According to an aspect of the containment System, the first injection device comprises a plurality of output ports spread inside the cavity, said output ports being fed with the first warm fluid.

According to an aspect of the containment System, the containment System further comprises a pipe having an inner tube forming an inner channel, and an outer tube surrounding said inner tube and forming an annular channel, and wherein the inner channel is used to extract the hydrocarbon fluid from the upper output opening and the annular channel is used to feed the dôme with at least a first warm fluid, or inversely.

According to an aspect of the containment System, the wall comprises a material that is a thermally isolating material.

According to an aspect of the containment System, the »

thermally isolating material has a thermal conductivity lower than 0.1 W.m^_1.K^-1.

According to an aspect of the containment System, the dôme comprises a material that is a thermally isolating material.

According to an aspect of the containment System, the thermally isolating material has a thermal conductivity lower than 0.1 W.m^-1.K^-1.

According to an aspect of the containment System, the containment System further comprises at least one sensor for measuring an interface level of a fluid interface between sea water and hydrocarbon fluid inside the dôme, at least one output valve connected to the upper output opening for outputting hydrocarbon fluid from the cavity, and a control unit for controlling said interface level on the bases of the interface level measured by the sensor.

According to an aspect of the containment System, the dôme comprises:

- a first output opening for extracting a first phase from the cavity, said first output opening being positioned on the dôme at a level proximal to the first level, said first phase being for example an oil phase of the hydrocarbon fluid, and

- a second output opening for extracting a second phase from the cavity , said second output opening being positioned on the dôme at a level proximal to a highest level of the dôme, said second phase being lighter than the first phase, and being for example a gas phase of the hydrocarbon fluid.

According to an aspect of the containment System, the dôme has an inner diameter greater to an outer diameter of the wall.

According to an aspect of the containment System, the dôme level is lower than half the first level so as to form an annular cavity comprised between the wall and the dôme , said dôme level being preferably lower than one tenth of the v</— first level, and more preferably lower than 1/20 of the first level.

According to an aspect of the containment System, the dôme further comprises a second injection device that inputs a second warm fluid into the annular cavity comprised between the wall and the dôme.

According to an aspect of the containment System, the second injection device comprises a plurality of output ports spread proximal to the peripheral lower end of the dôme, said output ports being fed with the second warm fluid.

According to an aspect of the containment System, the dôme comprises an upper portion extending in a radial direction from a centre vertical axis to an outer peripheral end, and a latéral portion extending the upper portion downwardly from said outer peripheral end at least down to the lower output opening.

According to an aspect of the containment System, the latéral portion comprises:

- a latéral rigid structure extending from the upper portion to a lower end intended to be seated on the seafloor at the base level, said latéral rigid structure not closing the latéral portion, and

- an extendable device that is extendable from the upper portion to the lower output opening, so as to close partially the latéral portion of the dôme.

According to an aspect of the containment System, the extendable device is a flexible member that is adapted to partially cover the latéral portion.

According to an aspect of the containment System, the flexible member is a thermally isolating material, having a thermal conductivity lower than 0.1 W.m^-1.^¹.

According to an aspect of the containment System, the latéral rigid structure incorporâtes injection pipes so as to form a first injection device that inputs a first warm fluid into the cavity.

According to an aspect of the containment System, the — latéral rigid structure is composed of a mesh of linked rigid beams, said rigid beam being formed of a structure material that is one of a list comprising a métal, a plastic, a material comprising fibres.

According to an aspect of the containment System, the dôme is adapted to be sealed above the wall, and the lower output opening is an over pressure valve that extract fluid out from the cavity into environment if a pressure différence between the cavity and the environment exceeds a predetermined pressure limit.

According to an aspect of the containment system, the lower output opening is a bail check valve.

Another object of the invention is to provide a method for using 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. The containment system comprises at least:

- a wall extending from a base level to a first level,

- a dôme forming a cavity under said dôme, said cavity being adapted for accumulating hydrocarbon fluid coming upwardly from the leaking device, said dôme comprising at least one output opening.

The containment System further comprises a lower output opening extending up to a dôme level, and the wall and the dôme are independent members.

The method comprises the following successive steps:

a) installing the wall around the leaking device on the seafloor, so as the base level corresponds to the seafloor, and said wall being substantially sealed to the seafloor around said leaking device,

b) installing the dôme above the wall, and

c) connecting the upper output opening to a pipe for extracting the hydrocarbon fluid from the cavity.

Thanks to the above method, the wall is firstly installed to cancel the thermal convection exchanges between the cold sea water and the hydrocarbon fluid. Secondly, the dôme can be landed on the seafloor and above the wall with no hydraulic perturbations, and without hydrate formation inside the cavity.

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

According to an aspect of the method, the dôme further comprises a first injection device, and during the step b), the first injection device inputs a first warm fluid into the cavity.

According to an aspect of the method, the containment System further comprises at least one sensor, at least one output valve connected to the upper output opening, and a control unit, and the method further comprises the following steps:

- the at least one sensor measures an interface level of a fluid interface between sea water and hydrocarbon fluid inside the dôme,

- the control unit calculâtes a control value of the at least one output valve on the bases of said measured interface level, and controls said at least one output valve for outputting hydrocarbon fluid from the cavity.

According to an aspect of the method, the dôme has an inner diameter greater to an outer diameter of the wall, and the dôme comprises an upper portion extending in a radial direction from a centre vertical axis to an outer peripheral end, and a latéral portion extending the upper portion downwardly from the outer peripheral end at least down to the lower output opening.

According to an aspect of the method, the latéral portion is an extendable device, and wherein after step b) or step c) , the extendable device is extended between the upper portion and the dôme level.

According to an aspect of the method, the lower ν' output opening is an over pressure valve that extract fluid out from the cavity into environment if a pressure différence between the cavity and the environment exceeds a predetermined pressure limit, and wherein after step b), the dôme is sealed above the wall.

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	eut	of a
containment System	according	to	a first embodiment	of	the
invention;
- Figure 2	is a schematic	view of a vertical	eut	of a
containment System	according	to	a second embodiment	of	the
invention;
- Figure 3	is a schematic	view of a vertical	eut	of a
containment System	according	to	a third embodiment	of	the
invention;
- Figure 4	is a schematic	view of a vertical	eut	of a
containment System	according	to	a forth embodiment	of	the
invention;
- Figures 5a to 5e are	perspective views of	a method
for using the <	containment	System, said method being

illustrated by viewing the installation steps of the containment System of Figure 4; and

- Figure 6 is a schematic view of a vertical eut of a containment System according to a fifth embodiment of the invention.

MORE DETAILLED DESCRIPTION

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

As shown on ail the embodiments of figures 1 to 6, the containment System 1 of présent invention 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 seafloor 5 is for example at more than 1500 meters deep below the sea surface 4. At this depth, the sea water 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 subsea well 3. The hydrocarbon fluid exiting from the subsea may be rather hot, for example above 50°C. However, the environment cold température and high pressure may transform the sea water and hydrocarbon fluid into hydrates having a quasi-solid or solid phase. These hydrates can fill and clogged any cavity.

The containment System 1 of présent 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 présent 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 présent invention comprises at least:

- a wall 10 extending from a lower end 10a at the base level to an upper end 10b at a first level Ll, said wall 10 being substantially sealed to the seafloor around the leaking device 2, and

- a dôme 20 situated above the wall 10 and forming a cavity 21 under said dôme 20, said dôme comprising at least an upper output opening (22).

The wall 10 and the dôme 20 are preferably independent parts or members, each of them installed at the seafloor independently from the other, and each of them being fixed preferably to the seafloor. The wall 10 is installed on the seafloor before the dôme 20, so as to cancel the convection of cold sea water before the installation of the dôme 2 0.

For example, the wall 10 comprises foot 10c having heavy weights for sealing and securing the wall 10 to the seafloor. The dôme 20 may hâve similarly foot 20c for securing it to the seafloor.

The wall 10 completely surrounds the leaking device 2. In a horizontal plane (XY), the wall 10 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 wall 10 has an outer diameter D10. This outer diameter corresponds to a maximum distance between two external points of the wall, taken in an horizontal plane at a level near the first level L1. The outer diameter D10 is for example of 6 meters or more.

The wall 10 then extends upwardly from a lower end 10a at the base level BL to an upper end 10b at the first level Ll. The first level L1 is preferably higher than a total height of the leaking device 2.

The wall 10 defines an inner wall volume 11. This volume 11 is substantially isolated (not in direct communication) with the environment sea water, according to a horizontal direction (XY) . The volume 11 is opened upwardly, according to a vertical direction (Z). Such wall 10 cancels any horizontal flow of sea water that is usually sucked by the flow of hydrocarbon fluid outputting from the leaking device 2. This dramatically reduces the thermal convection exchange between the cold sea water and the hydrocarbon fluid. This first effect cancels the hydrate formation.

The first level L1 is preferably at least twice the total height of the leaking device 2, and more preferably three times higher than it. The wall 10 can cancel efficiently the convection effect of cold sea water.

The dôme 20 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, and

- a latéral 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 latéral portion 25 has an inner diameter 020. This inner diameter D20 is wider than a total wide of the leaking device 2. For example, the inner diameter D20 is of 6 meters or more.

The latéral portion 25 of the dôme is downwardly opened.

The dôme 20 comprises an upper output opening 22 having of small diameter compared to the dôme diameter. Said upper output opening 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 the horizontal plane (XY), the dôme may hâve advantageously the same shape as the wall 10.

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

The hollow structure of the dôme 20 forms a largely opened cavity 21 in the direction to the seafloor. It is positioned above and around the wall 10. It is then above the leaking device 2 so as to accumulate the light hydrocarbon fluid.

The cavity 21 accumulâtes 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 advantageously comprises at least one sensor 60 for measuring the interface level IL of the fluid interface between sea water and the hydrocarbon fluid inside the dôme 20.

The sensor 60 may give a first measurement of a liquid level corresponding to the interface level IL between the liquid component of the hydrocarbon fluid (e.g. oil) and the sea water, and a second measurement of a gas level corresponding to an interface between the liquid component and a gas component (e.g. natural gas ) of the hydrocarbon fluid.

The containment System 1 additionally comprise 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.

Then, a control unit 61 calculâtes a control value on the bases of a measured value of the interface level IL, and opérâtes the output valve on the bases of the control value for outputting hydrocarbon fluid from the cavity. The control unit 61 may calculate the control value to keep the interface level at a constant level inside the cavity 21.

The containment System 1 may also comprise a first injection device 30 that injects a first warm fluid (WF) into the cavity 21. Therefore, the hydrocarbon fluid can be heated, and prevented to form hydrates.

The first injection device 30 may comprise a plurality of output ports spread inside the volume of the cavity, so as to ensure a constant warming of the hydrocarbon fluid inside the cavity 21.

The first injection device 30 may injects the first warm fluid WF from the upper portion 24, the latéral portion 25 or from both portions 24, 25 of the dôme 20.

The first warm fluid WF may be sea water pumped near the sea surface 4 via a pump 63. The pumped sea water may be used as it, i.e. at the température of sea water at the sea surface 4, or heated by additional means.

The first warm fluid may be water, oil, gas oil, or crude oil or any heat transfer fluid. The first warm fluid may be additionally heated or not.

The pipe 50 is advantageously 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 first injection System 30, and used to feed it with the first warm fluid from the surface. However, it is apparent that the two channel of such pipe can be connected to the dôme according to the other inverse possibility without any change.

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).

Advantageously, the cavity 21 can be used as a phase separator for separating the water and the hydrocarbon fluid, and for separating each phase of the hydrocarbon fluid (oil, gas) so as to extract them separately.

To this end, the dôme 20 may comprise:

- a first output opening for extracting a first phase from the cavity, said first output opening being positioned on the dôme at a level proximal to the first level Ll, said first phase being for example an oil phase of the hydrocarbon fluid, and

Thanks to the above first and second output opening, quantifies of each phase (oil, gas) can be limited inside the cavity 21 to predetermined values. An Archimedes force maximum that applies on the containment System 1 can be predetermined, and the weights of the foot 20c can therefore be predetermined for maintaining the containment System 1 landed at the seafloor 5.

The upper portion 24 of the dôme 20 may comprise output openings, called vents, for evacuating large quantifies of fluid inside the cavity 21. These vents are helpful to facilitate the installation of the containment System 1 above the leaking device 2. The vents are opened during the first transient steps of installation, noticeably when the containment System 1 is made to go down to the seafloor 5 around the leaking device 2. During these steps ail the hydrocarbon fluid may be evacuated to cancel its Archimedes force on the containment System and to prevent hydrates formation problem.

Moreover, the dôme 20 may comprises upper and latéral portions 24, 25 that comprise thermal isolating material, so as to thermally isolate the cavity 21 from the cold environment of sea water. Ideally, the thermally isolating material has a thermal conductivity lower than 0.1 W.m^-1.K^_1.

The following thermal isolation materials may be used: synthetic material such as Polyuréthane (PU) or polystyrène material, or a fibre textile with Polyvinyl chloride (PVC) coating or PU coating, or Alcryn ®. The T thermal isolation material may be foam, or a gel contained inside a double wall structure.

The wall 10 and dôme 20 may comprise a plurality of walls, layers or envelopes for improving the thermal isolation. Between the layers, isolation materials may be included, or heating devices (electric, hydraulic or of any kind) to improve again the thermal isolation of the wall and/or dôme.

The thermal isolation of the dôme 20 passively isolâtes the cavity 21, while the first injection device 30 actively isolâtes the cavity 21. Both effects prevent the formation of hydrates inside the cavity 21.

Additionally, the wall 10 may also comprise thermal isolating material to thermally isolate the wall volume 11 from the cold sea water. Ideally, the thermally isolating material has a thermal conductivity lower than 0.1 W-m’¹.^¹.

The same thermal isolation materials compared to those for the dôme may be used.

The wall 10 cancels the thermal convection exchange between the cold sea water and the hydrocarbon fluid and reduces a lot the thermal conduction exchange between the cold sea water and the hydrocarbon fluid, therefore preventing the formation of hydrates.

In the case of the embodiments of figures 1 to 5 (first to forth embodiments) , the inner diameter D2 0 of the dôme is then greater than an outer diameter D10 of the wall. The dôme 20 can surround the wall 10.

The dôme 20 further comprises a lower output opening 23 that is situated on the latéral portion 25 and that extends up to a dôme level DL. The dôme level DL is preferably lower or equal to the first level Ll.

The lower output opening 23 communicates with the environment sea water and is adapted to equal a cavity pressure of the cavity 21 to an environment pressure at the seafloor.

The lower output opening 23 additionally limits the level of hydrocarbon fluid inside the cavity 21.

An interface between the environment sea water and the hydrocarbon fluid accumulated inside the dôme cavity is an annular surface situated between the upper end 10b of the wall 10 and the latéral portion 25 of the dôme 20. The annular surface présents a much reduced area. Thanks to this feature, the thermal conduction exchange between the cold sea water and the hydrocarbon fluid contained inside the cavity is reduced. The hydrocarbon fluid contained inside the dôme cavity is not cooled by the sea water of said annular surface. And, the hydrates formation is prevented.

In the case of the first embodiment of figure 1, the dôme level DL of the lower output opening 23 is equal to the first level Ll of the upper end 10b of the wall 10.

The hydrocarbon fluid accumulâtes inside the cavity 21 from the upper output opening 22 down to said dôme level DL. In this case, the dôme 20 can be filled with hydrocarbon only down to the first level Ll (then egual to the interface level IL) as represented on figure 1.

The interface level IL may be higher than the first level Ll, depending on the flow of hydrocarbon fluid exiting from the leaking device 2 and the flow of hydrocarbon fluid exiting from the cavity by the upper output opening 22.

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

According to the second embodiment of figure 2, the dôme level DL is lower than the first level Ll : Then, the lower output opening 23 is lower than the first level Ll.

This feature increases the fluid path between the leaking device 2 and the sea water. The wall 10 and the latéral portion 25 of the dôme 20 form a chicane path. The volume between the wall 10 and the latéral portion 25 of the dôme 20 is an annular cavity 21a, that surrounds the wall 10.

The fluid interface (hydrocarbon fluid - sea water) inside the annular cavity 21a is the only direct interface between the cold sea water and the hydrocarbon fluid. This interface is an annular surface having a much reduced area. The conduction exchange is therefore highly decreased. The formation of hydrates is more prevented.

The cavity 21 and the annular cavity 21a are volumes storing a quantity of hydrocarbon fluid and absorbing the fluctuations of flows form the leaking device 2.

However, if the interface only moves inside the annular cavity 21a, no cold sea water can enter inside the cavity 21 above the leaking device 2. The volume of the annular cavity 21a is then preferred for compensating the fluctuations of flows from the leaking device 2.

Thanks to said annular volume 21a, the interface keeps a reduced area. The hydrocarbon fluid contained inside the dôme cavity is not cooled by the environment sea water. And, the hydrates formation is prevented.

Advantageously, the lower output opening 23 is proximal to the base level BL. For example, the dôme level DL is lower than half the first level Ll.

More advantageously, the dôme level DL is lower than one tenth the first level Ll.

More advantageously, the dôme level DL is lower than 1/20 of the first level Ll.

Thanks to the above features, the lower output opening 23 is proximal to the seafloor 5.

The annular cavity 21a has a bigger volume. The flows fluctuations can be most likely be compensated.

The cavity 21 is more isolated from the sea water: the thermal exchanges between the sea water and the hydrocarbon fluid inside the cavity 21 are more and more reduced. The formation of hydrates is more prevented.

The dôme 20 may further comprises a second injection device 40 that inputs a second warm fluid into the annular cavity 21a.

The second warm fluid may be identical to the first warm fluid.

The second warm fluid also prevents the hydrates formation from the lower output opening 23.

The third embodiment of figure 3 is similar to the second embodiment of figure 2: the dôme level DL is lower than the first level Ll. However, this dôme level DL is obtained progressively after the installation of the dôme 20 on the seafloor 5.

The latéral portion 25 of the dôme 20 comprises an extendable device 27 that can progressively cover and closes a rigid structure 26 that is not closing the latéral portion for the sea water.

The rigid structure 26 extends from the upper portion 24 to a lower end seated on the seafloor 5 (base level BL).

The extendable device 27 extends from the upper portion 24 to the lower output opening 23, or inversely. It keep the lower output opening 23 opened, and partially closes the latéral portion 25 so as to form the annular cavity 21a around the wall 10, as for the static second embodiment of figure 2.

The extendable device 27 may be composed of a plurality of déployable éléments that form a telescopic device, or may be composed of a flexible member.

The extendable device 27 may be composed of at least a thermally isolating material.

The isolating material may be a synthetic material such as Polyuréthane (PU) or polystyrène material, or a fibre textile with Polyvinyl chloride (PVC) coating or PU coating, or Alcryn ®.

For example, a extendable device 27 that is flexible, may be composed of a cover, a multilayer cover, a heated cover, an electrically heated cover, or a cover comprising a sealed isolating gel.

The thermal resistivity of the extendable device may be the same as the one of the dôme as disclosed above.

The figure 4 and figures 5a to 5e represent views of a containment System 1 designed according to the forth embodiment that is very similar to the third embodiment (figure 3). The forth embodiment uses a extendable device 27 that is a flexible member.

In these figure, a particular latéral rigid structure 26 is visible. Said latéral rigid structure 26 is composed of a mesh of linked rigid beams. These beams may be manufactured with a structure material such as métal, plastic, or a synthetic material comprising reinforcing fiber, such as carbon fiber.

Additionally, the latéral rigid structure 26 may incorporate injection pipes or by composed of pipes used as injection pipes so as to provide the first injection device 30, for injecting the first warm fluid inside the cavity 21.

The extendable device 27 in these figures is a flexible member that is progressively deployed from the upper portion 24 of the dôme 20.

In the embodiment of these figures, the wall 10 is also composed of at least a rigid structure and a flexible member progressively deployed from the upper end 10b of the wall, as soon as the wall 10 is installed on seafloor around the leaking device 2.

The figures 5a to 5e are more specifically illustrating the method for using or installing the containment System 1 according to the invention.

On figure 5a, the wall 10 is made to go down to the seafloor 5 around the leaking device 2, by a first descent tool.

On figure 5b, the wall 10 is landed on seafloor 5. The lower end 10a of the wall 10 is eventually sealed to the seafloor by any means. The wall 10 may be fixed to the seafloor only by the weights of the foot 10c or by other fixation means.

On figure 5c, the dôme 20 is made to go down to the seafloor 5 around the wall 10. It may be guided by the wall itself already fixed to the seafloor.

On figure 5d, the dôme 20 is landed on seafloor 5, and can be additionally fixed to the seafloor 5 if the weights of the foot 20c are not enough.

On figure 5e, the flexible extendable device 27 is deployed on the rigid structure 26 from the upper portion 24 of the dôme 20 to form the lower output opening 23.

During the steps of figure 5c to 5e, the injection device 30 may injects a warm fluid into the cavity 21. Events above the upper portion 24 may also be opened for facilitating the installation of the dôme 20.

The method will be again explained bellow, in view of ail the embodiments of the invention.

Figure 6 is presenting a fifth embodiment of the invention. According to the fifth embodiment, the inner diameter D20 of the dôme is substantially equal to the outer diameter D10 of the wall. In fact both éléments may hâve similar diameter.

The dôme 20 is sealed and fixed to the upper end 10b of the wall 10, for example by a corresponding collars or flanges 28 extending radially from each.

The wall 10 comprises the lower output opening 23. Said lower output opening 23 comprises an over pressure valve that extract fluid out of the cavity and into the environment if a pressure différence between the cavity 21 and the environment exceeds a predetermined pressure limit.

The predetermined pressure limit is for example of 10 bars, 20 bars, or 50 bars. This limit has to be determined accordingly with the cavity size and the leaking device flow.

The over pressure valve is for example a bail check valve. The bail check valve comprises a support element, a^ bail, and a spring that loads the bail to the support element so as to close an opening. The tuning of the spring load is adapted to the predetermined pressure limit.

Advantageously, the dôme 20 of présent embodiment is fed with warm fluid during the sealing and fixing step of the dôme 20 above the wall 10, so as hydrates formation is prevented.

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

The over pressure valve 23 insures that the pressure inside the cavity is not increasing, and then insuring that the containment System is not destroyed. Moreover, the predetermined pressure limit may insure that hydrates formation is prevented.

The fifth embodiment is advantageously having a control of the interface level IL as explained above.

The method for using or installing the containment System 1 according to the invention is now explained. The method comprises the following successive steps:

a) installing the wall 10 around the leaking device on the seafloor, so as the base level corresponds to the seafloor, and said wall being substantially sealed to the seafloor around said leaking device,

b) installing the dôme 20 above the wall,

c) connecting the upper output opening 22 to a pipe 50 for extracting the hydrocarbon fluid from the cavity 21.

Thanks to the above method, the thermal convection exchanges between the cold sea water and the hydrocarbon fluid is reduced even if the wall is opened upwardly.

The wall 10 cancels latéral movement of cold sea water at the seafloor around the leaking device 2. The sucking of cold sea water is cancelled or dramatically reduced.

The volume of fluid above the leaking device 2 inside the wall cavity 11 is rapidly heated by the hydrocarbon fluid itself.

As soon as the hydraulic and thermal conditions are steady around the leaking device 2 thanks to the previous installation of the wall 10, the dôme 20 can be installed above the wall 10.

The dôme can be landed on the seafloor and above the wall with no hydraulic perturbations, and without hydrate formation inside the cavity 21.

	In	case	of	first	to	forth embodiments,	the	dôme	is
landed	around	the	wall	10	therefore	forming	an	annular
cavity	21	that	is	useful	to	compensate	the fluctuations	of

flow from the leaking device 2.

In case of fifth embodiment, the over pressure valve embedded inside the lower output opening 23 ensures that pressure inside the cavity 21 is not increasing.

The dôme 20 may further comprise a first injection device 30, and during the step b) of the method, the first injection device 30 injects a first warm fluid WF into the cavity 21, to prevent the hydrates formation.

In case of the third and forth embodiment, after step b) or step c) of the method, the extendable device 27 is extended between the upper portion 24 and the dôme level DL.

Claims

1. A containment System (1) fluid from a leaking device that and that is leaking hydrocarbon for recovering hydrocarbon is situated at the seafloor 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 at least:

- a wall (10) extending from the base level to a first level (Ll) so as to completely surround the leaking device, said wall being substantially sealed to the seafloor around said leaking device, and

- a dôme (20) situated above the wall and forming a cavity (21) under said dôme, said cavity being adapted for accumulating hydrocarbon fluid coming upwardly from the leaking device, said dôme comprising at least one upper output opening (22) adapted to extract the hydrocarbon fluid for recovering, and wherein the containment System further comprises a lower output opening (23) extending up to a dôme level (DL), and wherein the wall (10) and the dôme (20) are independent members so as the wall can be landed on the seafloor before the dôme is installed.

2. The containment System according to claim 1, wherein the dôme (20) further comprises a first injection device (30) that inputs a first warm fluid (WF) into the cavity.

3. The containment System according to claim 2, wherein the first injection device (30) comprises a plurality of output ports spread inside the cavity, said output ports being fed with the first warm fluid.

4.

The containment System according to claim 2, further comprising a pipe (50) having an inner tube (51) forming an inner channel, and an outer tube (52) surrounding said inner tube and forming an annular channel, and wherein the inner channel is used to extract the hydrocarbon fluid from the upper output opening (22) and the annular channel is used to feed the dôme (20) with at least a first warm fluid (WF) , or inversely.

5. The containment System according to any one of the claims 1 to 4, wherein the wall (10) comprises a material that is a thermally isolating material.

6. The containment System according to claim 5, wherein the thermally isolating material has a thermal conductivity lower than 0.1 W.m^_1.K^_:L.

7. The containment System according to any one of the claims 1 to 6, wherein the dôme (20) comprises a material that is a thermally isolating material.

8. The containment System according to claim 7, wherein the thermally isolating material has a thermal conductivity lower than 0.1 W.m^_1.K^-1.

9. The containment System according to any one of the claims 1 to 8, further comprising at least one sensor for measuring an interface level (IL) of a fluid interface between sea water and hydrocarbon fluid inside the dôme (20) , at least one output valve connected to the upper output opening (22) for outputting hydrocarbon fluid from the cavity (21), and a control unit for controlling said interface level (IL) on the bases of the interface level measured by the sensor.

10.

The containment System according to any one of the claims 1 to 9, wherein the dôme (20) comprises:

11. The containment System according to any one of the claims 1 to 10, wherein the dôme (20) has an inner diameter (D20) greater to an outer diameter (D10) of the wall.

12. The containment System according to claims 11, wherein the dôme level (DL) is lower than half the first level (Ll) : so as to form an annular cavity (21a) comprised between the wall (10) and the dôme (20), said dôme level (DL) being preferably lower than one tenth of the first

level (Ll) , and more preferably lower than 1/20 of the first level (Ll).

13. The containment System according to claim 12, wherein the dôme (20) further comprises a second injection device (40) that inputs a second warm fluid into the annular cavity (21a) comprised between the wall (10) and the dôme (20).

14. The containment System according to claim 13, wherein the second injection device (40) comprises a plurality of output ports spread proximal to the peripheral lower end of the dôme, said output ports being fed with the second warm fluid.

15. The containment system according to any one of claim 11 to 14, wherein the dôme (20) comprises an upper portion (24) extending in a radial direction from a centre vertical axis (AX) to an outer peripheral end (24a) , and a latéral portion (25) extending the upper portion downwardly from said outer peripheral end at least down to the lower output opening (23).

16. The containment system according to claim 15, wherein the latéral portion (25) comprises:

- a latéral rigid structure (26) extending from the upper portion (24) to a lower end intended to be seated on the seafloor at the base level, said latéral rigid structure not closing the latéral portion, and

- an extendable device (27) that is extendable from the upper portion (24) to the lower output opening (23), so as to close partially the latéral portion (24) of the dôme.

17. The containment System according to claim 16, wherein the extendable device (27) is a flexible member that is adapted to partially cover the latéral portion (25).

18. The containment system according to claim 17, wherein the flexible member (27) is a thermally isolating material, having a thermal conductivity lower than 0.1 W.m^-1.K^_1.

19. The containment system according to claim 17, wherein the latéral rigid structure (26) incorporâtes injection pipes (26a) so as to form a first injection device (30) that inputs a first warm fluid (WF) into the cavity (21).

20. The containment System according to claim 17 wherein the latéral rigid structure (26) is composed of a mesh of linked rigid beams, said rigid beam being formed of au— structure material that is one of a list comprising a métal, a plastic, a material comprising fibres.

21. The containment System according to any one of the claims 1 to 10, wherein the dôme (20) is adapted to be sealed above the wall (20), and the lower output opening (23) is an over pressure valve that extract fluid out from the cavity into environment if a pressure différence between the cavity and the environment exceeds a predetermined pressure limit.

22. The containment System according to claim 21, wherein the lower output opening (23) is a bail check valve.

23. A method for using the 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, and wherein the containment System (1) comprises at least:

- a wall (10) extending from a base level to a first level (L1),

- a dôme (20) forming a cavity (21) under said dôme, said cavity being adapted for accumulating hydrocarbon fluid coming upwardly from the leaking device, said dôme comprising at least one upper output opening (22), and wherein the containment System further comprises a lower output opening (23) extending up to a dôme level (DL), and wherein the wall (10) and the dôme (20) are independent members, and wherein the method comprises the following successive steps:

a) installing the wall (10) around the leaking device on the seafloor, so as the base level corresponds to the seafloor, and said wall being substantially sealed to the seafloor around said leaking device,

b) installing the dôme (20) above the wall,

c) connecting the upper output opening (22) to a pipe (50) for extracting the hydrocarbon fluid from the cavity.

24. The method according to claim 23, wherein the dôme (20) further comprises a first injection device (30), and at least during the step b), the first injection device (30) inputs a first warm fluid (WF) into the cavity.

25. The method according to any one of the claims 23 to 24, wherein the containment system (1) further comprises at least one sensor, at least one output valve connected to the upper output opening (22), and a control unit, and wherein the method further comprises the following steps:

- the at least one sensor measures an interface level (IL) of a fluid interface between sea water and hydrocarbon fluid inside the dôme (20),

- the control unit calculâtes a control value of the at least one output valve on the bases of said measured interface level, and controls said at least one output valve for outputting hydrocarbon fluid from the cavity (21).

26. The method according to any one of the claims 23 to 25, wherein the dôme (20) has an inner diameter (D20) greater to an outer diameter (D10) of the wall, and the dôme (20) comprises an upper portion (24) extending in a radial direction from a centre vertical axis (AX) to an outer peripheral end (24a), and a latéral portion (25) extending the upper portion downwardly from the outer peripheral end (24a) at least down to the lower output opening (23).

27. The method according to claim 26, wherein the latéral portion (25) is an extendable device (27), and wherein after step b) or step c), the extendable device is extended between the upper portion (24) and the dôme level (DL).

28. The method according to any one of the claims 23 to 25, wherein the lower output opening (23) is an over pressure valve that extract fluid out from the cavity into environment if a pressure différence between the cavity and the environment exceeds a predetermined pressure limit, and wherein after step b) , the dôme (20) is sealed above the wall (20) . yZ