FR3037343A1 - WATER COLLECTION ASSEMBLY FROM A SURFACE OR WATER EXTENDED STRUCTURE, INSTALLATION AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

An assembly (18) for taking water from a structure (14) disposed on the surface or in a body of water (12), the assembly (18) comprising: - an elongated frame member extending along a direction of elevation (Z) - a flexible water withdrawal pipe (32) for connection to the structure (14) and extending along the elevation direction (Z) ), and - a spacer (34) integral with the frame member, the spacer (34) laterally guiding the flexible pipe (32) relative to the frame member, characterized in that the element frame comprises a first rigid part intended to be rigidly connected to the structure (14) and a second rigid part articulated on the first rigid part by at least one articulation member.

Description

The present invention relates to a set of water sampling from a structure arranged at a surface disposed in the surface or in a body of water, an installation and a method of manufacturing the same. the surface or in a body of water, the assembly comprising: - at least one elongated frame element extending along an elevation direction, - at least one flexible water withdrawal pipe intended for be connected to the structure and extending along the elevation direction, and - at least one spacer integral with the framing member, the spacer laterally guiding the flexible pipe relative to the framing member . Such a water sampling assembly is intended to be deployed, for example, from an offshore fluid exploitation structure, to allow the supply of water at low temperature in the offshore structure. The liquid transport of natural gas extracted at sea has many advantages in terms of volume and operating flexibility. For this purpose, floating barges including a hydrocarbon processing unit and liquefaction of natural gas are currently exploited. These offshore structures are called FLNG (acronym for "Floating Liquified Natural Gas" for Floating Natural Gas Liquefaction Plant).

The liquefaction of natural gas requires a significant cooling thermal energy. At sea, a significant source of cold is obtained by taking water at depth, for example, a few hundred meters under the offshore structure. To ensure such a sampling, it is known to deploy, from the offshore structure, tubular water withdrawal lines which dive vertically to the appropriate depth to collect water at the desired temperature. Such lines are subject to variable environmental conditions such as the dynamic movements of the offshore structure, underwater currents likely to oscillate these lines over their entire length. Depending on the amplitude and the frequency of repetition of the oscillations, the flexible lines are likely to twist, or even to clash, and thus to be damaged. Therefore, an object of the invention is to provide a set of deep water sampling from an offshore structure, which is reliable and able to withstand variable environmental conditions. To this end, the subject of the invention is an assembly of the abovementioned type, in which the frame element comprises at least a first rigid part intended to be rigidly connected to the structure and at least a second rigid part hinged to the first rigid part by at least one articulation member. The assembly according to the invention may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination: the framework element comprises at least a third rigid part and a body of articulation connecting the third rigid portion to the second rigid portion, the length of the second rigid portion and the third rigid portion being strictly greater than 10 meters, - the framing member comprises a number of hinge members between 10 and 4, - the or each hinge member is selected from a pivoting joint, a ball joint or a flexible joint, - the frame member is metal, - the spacer is fixed axially on a part rigid of the frame member, the flexible pipe being slidably mounted axially in the spacer; the spacer defines at least one passage lumen of the flexible pipe; the length of the flexible pipe; is substantially the same as the length of the frame member, - the flexible pipe comprises a plurality of end-to-end flexible sections, - the length of at least one section of the flexible pipe is greater than or equal to 11 meters, - the assembly comprises a cluster of flexible pipes mounted jointly on a common frame element.

The invention also relates to a fluid operating installation comprising: - a surface structure, and - a water sampling assembly as described above, a first rigid portion of the frame element being connected rigidly to the structure, a second rigid portion of the frame member being hinged to the first portion away from the structure, the height separating the structure of the second portion being preferably strictly greater than 1 meter. The installation may comprise the following feature: the structure comprises a fluid treatment unit, in particular a natural gas liquefaction plant.

The invention also relates to a method of manufacturing a water sampling assembly from a structure disposed on the surface or in a body of water, the method comprising: minus a flexible water withdrawal pipe intended to be connected to the structure and extending along the elevation direction, - the assembly of at least a first rigid part intended to be rigidly connected to the structure with at least a second rigid portion hinged to the first portion by at least one hinge member to provide an elongate frame member extending along the elevation direction; frame member, and - the lateral guide, by the spacer, of the flexible pipe relative to the frame member. The method according to the invention may furthermore comprise: the determination of information representative of the oscillations of the flexible pipe in the body of water as a function of predefined meteorological conditions, and the calculation of the length of the rigid parts the framing member, the number of hinge members and / or the position of the spacer (s) depending on the representative information. The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a diagrammatic view taken in partial section, of a fluid operating system according to the invention, comprising a water sampling assembly provided with flexible pipes and an elongated frame member; FIG. 2 is a view similar to FIG. the flexible pipes having been removed from this FIG. 2 to highlight the elongated frame element; FIG. 3 is a view of a detail of the water withdrawal assembly of FIG. 1 illustrating a rigid part; of the elongate framing member, sections of the flexible ducts and a spacer, FIG. 4 is a schematic view of a rigid member hinge member of the framing member of FIG. FIG. 5 is a schematic view of a section FIG. 6 is a graph illustrating the relative amplitude of the lateral oscillations of a flexible pipe of FIG. 1 ("clean" modes of vibration or resonance) as a function of the length of the flexible pipe of FIG. the flexible pipe and meteorological conditions, and FIGS. 7 to 10 are successive views taken in partial section, of the fluid exploitation installation of FIG. 1, when the flexible pipes are subjected to different modes of operation. oscillations. A fluid operating installation 10 is illustrated in FIGS. 1 to 5.

The installation 10 is intended in particular to collect and treat a recovered fluid at the bottom of a body of water 12, more specifically below the seabed. The fluid is advantageously a fluid containing hydrocarbons, such as natural gas. In particular, the installation 10 is intended for the treatment and liquefaction of a natural gas recovered at the bottom of the body of water 12, with a view to its transport in liquid form to the ground. The body of water 12 is, for example, a sea, an ocean, a lake or a river. The depth of the water extent 12 to the right of the installation 10 is, for example, between 50 meters (m) and 3000 m and even beyond.

As illustrated by FIGS. 1 and 2, the installation 10 comprises a structure 14 disposed on the surface of the water body 12, and advantageously a fluid treatment unit 16 carried by the structure 14. According to FIG. invention, the installation 10 comprises an assembly 18 for taking water under the structure 14, at a depth that can range from 50 m to 3000 m.

In this example, the structure 14 is a floating structure, such as a barge, or a floating platform. Alternatively, the structure 14 is fixed on the bottom of the body of water 12. The structure 14 comprises a shell 20 carrying the unit 16. It delimits a well 22, also called "moon-pool" in English (translated in French by "central well"), through the shell 20 to accommodate the sampling assembly 18. Alternatively, the well 22 is located in a structure located outside the shell 20. The unit 16 is of preferably a liquefaction unit of natural gas. It comprises at least one utility 24 for receiving cold water from the sampling assembly 18. The utility 24 is, for example, an exchanger. The sampling assembly 18 comprises at least one elongated frame element 30 extending along a direction of elevation Z. The sampling assembly 18 further comprises at least one flexible pipe 32 for sampling water and at least one spacer 34 integral with the frame member 30. The spacer 34 allows to guide laterally in a lateral direction 3037343 5 Y, perpendicular to the elevation direction Z, each flexible pipe 32 relative to to the framing member 30. The elongated framing member 30 is adapted to serve as a "skeleton" for supporting the set of flexible lines 32 of the water withdrawal assembly 18.

Advantageously, the elongate framing member 30 is located in the middle of a cluster of flexible ducts 32 in a plane perpendicular to the elevation direction Z. In the example illustrated in FIG. 2, the elongated element frame 30 comprises at least a first rigid portion 41 intended to be rigidly connected to the surface structure 14 and at least a second rigid portion 42 articulated on the first rigid portion 41 by at least one articulation member 40. The first rigid part 41 is secured to the structure 14 by the weight of the frame 30, for example, when the frame comprises a flange resting on a support surface of the structure 14. Alternatively or in addition, the first rigid part 41 is bolted to the structure 14, according to calculated dynamic stresses.

When the first rigid part 41 is connected to the structure 14, the height h1 (visible in FIG. 2) separating the structure 14 from the second rigid part 42 directly articulated on the first rigid part 41 by means of a body articulation 40 is advantageously strictly greater than 1 m. Advantageously, the frame member 30 comprises a plurality of rigid portions and a plurality of hinge members 40 interconnecting the rigid portions. More specifically, the number of articulation members 40 is understood in the broad sense between 1 and 4. The number of rigid parts is therefore in the broad sense between 2 and 5. In the example illustrated in Figures 1 to 5, the frame element 30 comprises two articulation members 40 and three rigid parts: the first rigid part 41 25 connected to the structure 14, the second rigid part 42 articulated on the first rigid part 41 by a first articulation member 40 and a third rigid portion 43 articulated on the second portion 42 by a second articulation member 40. The length of each rigid portion 42, 43, with the exception of the first rigid portion 41 connected to the structure 14, is strictly greater than 10 m.

The rigid parts of the frame member 30 are, for example, metal. The articulation member (s) 40 are, for example, pivot joints, ball joints or flexible joints. An example of articulation member 40 is illustrated in FIG. 4. Such articulation member 40 comprises a first portion 44 intended to receive a first rigid portion and a second portion 46 intended to receive a second rigid portion. In addition, the articulation member 40 also comprises a central portion 48 intended to connect the first rigid portion located in the first portion 44 to the second rigid portion located in the second portion 46. For this, the central portion 48 is pivotable on itself to articulate to each other the rigid portions introduced into each of the portions 44, 46.

The pivot angle between the first portion 44 and the second portion 46 is for example between 00 and 45 °. The flexible pipe 32 for drawing water is intended to be connected to the structure 14. Such a flexible pipe 32 extends along the elevation direction Z, that is to say along the element elongated frame 30.

In the embodiment illustrated in FIGS. 1 to 5, the sampling assembly 18 comprises a cluster of eight flexible pipes 32 mounted jointly on a frame member 30 which is common to them. The number of flexible pipes 32 is, for example, adapted according to the desired quantity of water to be taken or according to the desired flow rate of water withdrawal.

The length of the flexible pipes 32 is substantially the same as the length of the frame member 30. By the term "substantially" it is advantageously understood to be plus or minus 5 percent (° / 0). Each flexible pipe 32 is connected in its upper part to the structure 14.

In this example, each flexible pipe 32 further comprises a plurality of flexible sections 44 mounted end to end. An example of a flexible section 44 is illustrated in FIG. 5. Such flexible sections 44 are, for example, made of a flexible and elastic material such as rubber comprising metal reinforcements in different layers.

The length of at least one section 44 is greater than or equal to 11 m. In order to collect the water in the body of water, at least the lower sections of each flexible pipe 32 are formed of a strainer delimiting openings for the passage of water and making it possible to filter the water taken off. By the term "lower section of a flexible pipe 32" is meant the section 44 of a flexible pipe 32 intended to be located most deeply in relation to the surface structure 14 when the flexible pipe 32 is connected to the structure 14. The spacer 34 is adapted to laterally guide, in the lateral direction Y, the flexible pipes 32 relative to the frame member 30. The spacer 34 locally limits the lateral movements of the flexible pipes 32 preventing them from becoming entangled.

For this, the spacer 34 is fixed axially on one of the rigid parts of the frame member 30. For example, the spacer 34 is fixed by welding on the corresponding rigid part. The spacer 34 delimits at least one passageway 45 of a flexible pipe 32. In the example illustrated in FIG. 3, the spacer 34 defines a plurality of passage apertures 45, here eight passage apertures 45, making it possible to passing the flexible pipes 32 of the sampling assembly 18 into the passage apertures 45 of the spacer 34. The flexible pipes 32 are mounted to slide axially and in rotation in the spacer 34. On the other hand, the flexible pipes 32 are maintained at a substantially fixed distance from the frame member 30 in the lateral direction Y by the spacer 34. In the example illustrated in Figures 1 and 2, the number of spacer 34 is equal to three so laterally guiding the flexible pipes 32 with respect to the elongated frame member 30 over the entire length of the flexible pipes 32 and the elongated frame member 30. The number of spacers 34 depends on the length of the conductive elements. This number also depends on the number of rigid sections 41, 42, 43 of the frame member 30, and this as a function of the eigenmodes of dynamic responses illustrated by FIG. Figure 6. The spacers 34 are made of a rigid material to withstand contact loads exerted by the flexible pipes 32 and the elongated frame member 30. For example, the spacers 34 are made of metal. The method of manufacturing a fluid withdrawal assembly 18 from a structure 14 disposed on the surface or in a body of water 12 will now be described. As indicated above, the assembly 18 comprises at least one flexible pipe 32 for drawing water intended to be connected to the structure 14 and extending along the direction of elevation Z.

Initially, depending on the length of the flexible pipe 32 to be mounted, an operator determines, for example via a computing unit, information representative of the oscillations of the flexible pipe 32 in the body of water depending on conditions. predefined meteorological conditions. The predefined meteorological conditions are, for example, a predefined wave level, the dynamic movements of the offshore structure (induced by the swell) or a speed of underwater currents.

The information representative of the oscillations of the flexible pipe 32 is, for example, represented in the form of a graph representing the relative amplitude of the lateral oscillations of the flexible pipe 32 as a function of the length of the flexible pipe 32, such as illustrated in Figure 6.

In particular, in the graph of FIG. 6, each of the curves 50, 52, 54, 56 corresponds to a mode of oscillation of the flexible pipe 32 for predefined meteorological conditions. Such a mode of oscillation is also called "eigen mode of vibration" or "eigen mode of resonance". A mode of oscillation of the flexible pipe 32 corresponds to oscillations of the flexible pipe 32 repeated periodically over the entire length of the flexible pipe 32. The number of periods is therefore a function of the length of the flexible pipe 32. Typically, for a flexible pipe 32 extending over a length of 225 m in a body of water, the first periods of the modes will be 45 seconds (s) for the curve 50, 13 s for the curve 52, 5 s for curve 54 and 2.6 s for curve 56. The manufacturing method then comprises calculating, as a function of the determined representative information, the number of rigid portions of the frame member 30, the length of each rigid portion of the framing member 30, the number of hinge members 40 of the framing member 30 and / or the position of the strut (s) 20 34. The length of the parts rigid of the frame member 30 and the number of articular members For example, depending on the period of the oscillations, the elements 40 are determined so that the frame element 30 follows the oscillations of the flexible pipe 32 tangentially.

Advantageously, the elongate frame member 30 comprises as many hinge members 40 as extrema number lateral oscillations along the entire length of the flexible pipe 32. Preferably, the position of the spacers 34 is chosen so that maintaining a substantially constant distance between the flexible pipes 32 and the elongated frame member 30 over the entire length of the flexible pipe 32 while permitting bending of the frame member 30 where the articulation 40. The spacers 34 are, for example, arranged at the maximum lateral oscillations determined for the flexible pipe 32 to limit the amplitude of these maximum oscillations.

For example, the curve 50 of the graph of FIG. 6 comprises only one extremum of lateral oscillations along the entire length of the flexible pipe 32. FIG. 7 illustrates the choice, as a function of this curve 50, of the characteristics of the rigid parts and hinge members 40 of the frame member 30, and the position of the spacers 34 so that the flexible pipes 32 oscillate without damaging the assembly 18. Thus, in this Figure 7, the element The frame member 30 comprises two rigid portions and a hinge member 40. Advantageously, when the frame member 30 comprises a single hinge member 40, the hinge member 40 is located near the hinge connection 40. frame member 30 with the structure 14 so as to minimize the risk of fracture of the framing member 30 at that location. Likewise, the curve 52, respectively 54, respectively 56, of the graph of FIG. 6 is used to select the elements of the sampling device 18 of FIG. 8, respectively 9 and 10, respectively. The method then comprises the mounting of the flexible pipe 32. The method also comprises the assembly, according to the calculated characteristics of the rigid parts and the articulation members 40, of at least a first rigid portion 41 intended to be rigidly connected to the structure 14 with at least a second rigid part 42 articulated on the first part 41 by at least one articulation member 40. This thus makes it possible to obtain an elongated frame element 30 extending along a direction of elevation Z. When element 30 comprises a number of rigid parts greater than two, the rigid parts are assembled end to end by means of several articulation members 40. Then, the manufacturing method comprises attaching at least one spacer 34 to the frame member 30 at a previously calculated position. The fixing of the spacer 30 is made by welding, for example. Each flexible pipe 32 is then introduced into a passage lumen 45 of the spacer 34 so as to laterally guide each flexible pipe 32 relative to the frame member 30. In operation, the sampling assembly 18 is placed in place in the structure 14 disposed on the surface or in a body of water. Then, water is drawn through the strainers of the lower sections of the flexible pipes 32 to the structure 14. Thus, the sampling assembly 18 anticipates the possible movements of the flexible pipes 32 according to predetermined variable meteorological conditions. . The elongated framing member 30 follows the oscillations of the flexible pipes 32 by virtue of the presence of the hinge members 40 placed at the deformation nodes of the ducts, thus preventing a break-up or embrittlement of the elongated frame element 30 and therefore of the collection set 18.

The spacers 34 make it possible to maintain a substantially constant distance between the flexible pipes 32 and the frame member 30 and thus prevent the flexible pipes 32 from overlapping and becoming damaged. The sampling assembly 18 is solid and reliable since the presence of the frame member 30 limits the lateral movements of the flexible pipes 32, limiting the risks of entanglements and collisions of these flexible pipes 32, as well as the constraints applying to flexible pipes 32. 10

Claims (15)

CLAIMS1.- A set (18) for taking water from a structure (14) disposed on the surface or in a body of water (12), the assembly (18) comprising: - at least one elongated element frame (30) extending along an elevation direction (Z), - at least one flexible water withdrawal pipe (32) for connection to the structure (14) and extending along the elevation direction (Z), and - at least one spacer (34) integral with the frame member (30), the spacer (34) laterally guiding the flexible pipe (32) relative to the framing member (30), characterized in that the framing member (30) comprises at least a first rigid portion (41) to be rigidly connected to the structure (14) and at least a second portion rigid (42) articulated on the first rigid portion (41) by at least one articulation member (40). 2. An assembly (18) according to claim 1, wherein the frame member (30) comprises at least a third rigid portion (43) and a hinge member (40) connecting the third rigid portion (43). at the second rigid portion (42), the length of the second rigid portion (42) and the third rigid portion (43) being strictly greater than 10 meters. 3. An assembly (18) according to claim 1 or 2, wherein the frame member (30) comprises a number of hinge members (40) between one and four. 4. An assembly (18) according to any preceding claim, wherein the or each hinge member (40) is selected from a swivel joint, a ball joint or a flexible joint. 5. An assembly (18) according to any one of the preceding claims, wherein the frame element (30) is made of metal. 6. An assembly (18) according to any preceding claim, wherein the spacer (34) is axially fixed to a rigid portion (41, 42, 43) of the frame member (30), the flexible pipe (32) being slidably mounted axially in the spacer (34). 3037343 12 7. An assembly (18) according to claim 6, wherein the spacer (34) defines at least one passage lumen (45) of the flexible pipe (32). 5 8. An assembly (18) according to any one of the preceding claims, wherein the length of the flexible pipe (32) is substantially identical to the length of the frame member (30). 9. An assembly (18) according to any one of the preceding claims, wherein the flexible conduit (32) comprises a plurality of flexible sections (44) mounted end to end. 10. An assembly (18) according to claim 9, wherein the length of at least one section (44) of the flexible pipe (32) is greater than or equal to 11 meters. 15 11. An assembly (18) according to any one of the preceding claims, wherein the assembly (18) comprises a cluster of flexible pipes (32) mounted together on a common frame member (30). 20 12.- Fluid extraction installation comprising: - a surface structure (14), and - a water withdrawal assembly (18) according to any one of claims 1 to 11, a first rigid portion (41) the framing member (30) being rigidly connected to the structure (14), a second rigid portion (42) of the framing member (30) being hinged to the first portion (41) at the distance from the structure (14), the height (h1) separating the structure (14) of the second portion (42) being advantageously strictly greater than 1 meter. 13. The plant of claim 12, wherein the structure (14) comprises a fluid treatment unit (16) including a natural gas liquefaction plant. 14. A method of manufacturing an assembly (18) for taking water from a structure (14) disposed on the surface or in a body of water (12), the method comprising: - mounting at least one flexible water withdrawal pipe (32) for connection to the structure (14) and extending along the elevation direction (Z), least a first rigid portion (41) intended to be rigidly connected to the structure (14) with at least a second rigid portion (42) articulated on the first portion (41) by at least one articulation member (40) to obtain an elongate framing member (30) extending along the elevation direction (Z), - fixing a spacer (34) to the framing member (30), and - guiding lateral, through the spacer (34), the flexible pipe (32) relative to the frame member (30). 10 15. The manufacturing method according to claim 14, further comprising: determining a piece of information representative of the oscillations of the flexible pipe (32) in the body of water as a function of predefined meteorological conditions, and - the calculation the length of the rigid portions (41, 42, 43) of the frame member (30), the number of hinge members (40) and / or the position of the spacer (s) (34) according to the representative information.