OA17574A - Floating support anchored on a reel comprising a guide pipe and flexible pipe offset within said reel. - Google Patents

Abstract

The present invention relates to a floating support (1) for oil production comprising a reel (2) crossed by a plurality of first flexible pipes (4, 4a4c) connected (7) to an upper platform (2c) characterized in that said reel comprises at least one guide and offset pipe (5) capable of containing and guiding a said first flexible pipe (4), passing non-vertically through the interior of said cylindrical internal structure (2a) of the reel between: a) said bottom wall (2b) at a first location (C1) of said bottom wall where said guide pipe is fixed, and b) an internal platform (6) above said bottom wall, the upper end (5c) of said guide pipe (5) being fixed (6b) to said internal platform (6) at a second location (C2) where the upper end (4-3) of said flexible pipe (4) contained in said pipe is fixed or is capable of being fixed. guide, said second location being vertically unaligned with said first location.

Description

Floating support anchored on a reel comprising a guide pipe and flexible pipe offset within said reel

The present invention relates to a fund-surface connection installation between a plurality of submarine pipes resting on the seabed and a support floating on the surface, comprising a plurality of flexible pipes, the upper end of which is secured to a reel substantially fixed by relative to the seabed, the floating support pivoting freely around said reel, the latter being situated at the front of the floating support or within said floating support, generally in the front third of said floating support.

The present invention also relates to a said floating support anchored on a reel.

The technical sector of the invention is more particularly the field of the manufacture and installation of production risers for the underwater extraction of oil, gas or other soluble or fusible material or of production. 'a suspension of mineral matter from a submerged wellhead to a floating support, for the development of production fields installed in the open sea off the coast. The main and immediate application of the invention being in the field of oil production.

The technical sector of the invention is more particularly the field of underwater oil production in areas of difficult or extreme ocean-weather conditions, or even in arctic and antarctic areas, from floating supports.

A floating oil production support generally includes anchoring means to remain in position despite the effects of currents, winds and swells. It also generally comprises means for drilling, storing and treating the oil as well as means for unloading to stripping oil tankers, the latter appearing at regular intervals to carry out the removal of the production. The usual name for these floating supports or vessels is the term U "

Anglo-Saxon Floating Production Storage Offloading (meaning floating average of storage, production and unloading) which we will use the abbreviated term FPSO throughout the following description, or FDPU or Floating Drilling & Production Unit (meaning floating average of drilling and production), when the floating support is also used to carry out drilling operations with a well deviated in the height of the water section.

When the oceano-weather conditions, that is to say the swell, the wind and the current are important, even extreme, in the case of storms, it is preferable to anchor the FPSO at the level of a reel, generally located at known manner at the front or in the front third of the ship and in the axis, the ship being free to turn around said reel according to the wind, current and swell. Thus, wind, current and swell exert specific forces on the hull and the superstructures, the FPSO due to its degree of freedom of rotation around the vertical axis ZZ, coming naturally to the position of least resistance. The pipes ensuring the connection with the wellheads are generally connected to the underside of the reel and connected to the FPSO by means of a rotating joint integrated in the axis of said reel, generally located at the level of the bridge of said FPSO . When the weather conditions can become extreme, as in the North Sea, in the Gulf of Mexico or in the arctic or antarctic zone, the FPSO can generally be disconnected so as to be able to take shelter while waiting for acceptable operational conditions.

A floating oil production support comprising a system for mooring anchor lines to the seabed and bottom-to-surface connection pipes anchored on a reel comprises, in a known manner:

a rotary device called a "drum", comprising an internal cylindrical structure, preferably of circular section, within a cavity passing through the shell of the floating support over its entire height, said internal cylindrical structure being articulated in rotation with respect to said shell by means of rotating guiding elements, in particular at least one rolling or friction bearing, preferably a rolling bearing comprising rollers and guide tracks of said t

casters, so as to allow the rotation of said floating support around a substantially vertical axis ZZ 'of said internal cylindrical structure and of said cavity, without significantly causing the rotation of said internal cylindrical structure with respect to the same vertical axis ZZ' , and

- A lower mooring structure allowing the mooring on the one hand of said anchor lines and on the other hand the connection of first flexible pipes connected to the underwater pipes resting on the seabed directly or via connecting pipes bottom-surface, said mooring structure being arranged below the hull of the floating support, fixed to a submerged bottom wall of said internal cylindrical structure, and therefore integral with said internal cylindrical structure, so that the mooring lines and say flexible pipes connected to it are not rotated when the floating support is rotated, and

- second flexible pipes connected to said first flexible pipes or in continuity thereof going up within the cavity to a connector of the type called rotary joint connector, comprising a first part integral with the deck of said hull connected to a plurality of conduits or lines at deck level, and a second part integral with an upper platform of said internal cylindrical structure located above sea surface level, the upper ends of said second flexible conduits rising within said cylindrical internal structure of the reel, being connected, in general via elbow pipe elements, to said second connection part, said first part of the connection integral with the floating support at the level of the bridge of the floating support, being articulated in rotation with respect to said second part of the connection integral with said cylindrical internal structure, via a rotating joint so as to allow ize the rotation of said floating support without causing the rotation of the ends of said second flexible pipes within said cylindrical internal structure.

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The rolling bearing is either located at the level of the floating support bridge, or located in the lower part in a wet area, that is to say that the bearing is submerged, or again in combination of the two preceding configurations.

Preferably, said bottom wall of said internal cylindrical structure is assembled therewith in a sealed manner to prevent the submerged part of the interior of said internal structure from being invaded by sea water. This sealing makes it easier maintenance operations and other personnel intervention in the reel, in particular for the connection of flexible pipes. But, above all, this sealing allows an Archimedean thrust to be applied to the volume displaced by said cylindrical internal structure of the reel and partly relieves the vertical forces generated by the anchor lines, by said flexible ducts at the level of the guiding elements and compensates for the own weight of said cylindrical internal structure.

Numerous bottom-to-surface connection configurations have been developed, in particular in the Applicant's patents WO 2009/122098, WO 2009/122099, WO 2010/026334 which describe an FPSO equipped with such a reel and associated flexible pipes, more particularly intended for the extreme conditions encountered in the arctic. Such a configuration is interesting for average water depths, that is to say from 100 to 350m, or even 500-600m. In particular, the implementation of flexible pipes over the entire height of the water section between the rigid underwater pipes resting on the seabed and the floating support allows greater movements of the floating support than when placing implementation of rigid pipes.

When the water depth reaches 1000-1500m, or even 2000-3000m, the installation of flexible pipes on the height of the water section becomes very expensive because these flexible pipes are very complex and very delicate to manufacture and one prefers so-called hybrid tower-type bottom-to-surface connections, in which the substantially vertical portion of the tower consists of rigid pipes between the seabed and up to ♦

a distance of approximately 50 to 100m from the surface of the water, the upper ends of the rigid pipes then being connected to the FPSO by flexible pipes 150 to 350m in length in the form of a chain or double plunging chain. Numerous patents of the applicant illustrate advantageous arrangements for producing this type of bottom-surface connection, in particular WO 2011/144864 of the applicant.

An oil field generally consists of a plurality of wellheads located at varying distances up to several kilometers from the FPSO, each of them being connected by either rigid or flexible pipes, umbilicals and electric cables. . In general, the bottom-to-surface connection of a said well head comprises at least one production line for petroleum or the injection of water or gas, plus an umbilical for controlling the well head and, if applicable one or more electric cables. These rigid or flexible pipes, umbilicals and cables are laid on the seabed next to each other and must not overlap on their route. Thus, the arrangement of the flexible pipes on the underside of the reel and their connection to the reel are conditioned by the arrangement of the then heads and of the submarine pipes resting on the seabed constituting the architecture of the field. On the other hand, in some cases, a large number of bottom-surface connections is required, and, to avoid interference between said pipes in the water section, said flexible pipes are found placed next to each other and close to each other. from each other, possibly on one or more circles, in the same order in which the ends of the pipes resting on the seabed are located, one next to the other at seabed level 10.

The Applicant's patent WO 2011 / 061422A1 describes an FPSO not equipped with a reel, but permanently anchored, heading north, on 16 anchor lines, a plurality of bottom-surface links coming from the west, coming to join all along the plating, thus constituting a large concentration of pipes coming from one direction.

It follows that, in certain field configurations, we

W will find on the periphery of the reel, in particular on the periphery of the lower mooring structure and / or of the bottom wall of said internal cylindrical structure, a concentration, over a small area, of flexible pipes of large diameter, therefore of high linear weight, connected over a reduced angular zone of the periphery while in a diametrically opposed zone, there will be only flexible pipes or cables of low linear weight, or even no pipe in some cases. Figure 4, commented on below, illustrates this type of arrangement.

However, a flexible pipe in suspension connected to the reel exerts on the latter a tension taken up by the reel at its connection to said reel, this tension generates significant vertical forces (of force intensity F), as well as horizontal forces ( of lower force intensity H) at their connection to the reel, in particular in the case of a very deep bottom-surface connection. Consequently, an irregular and / or asymmetrical distribution of flexible pipes generates variations in force and therefore significant stress along the periphery of the drum transferred and taken up inhomogeneously, in particular at the level of said rotating guide elements. In addition, on an offshore oil field there is generally a predominant direction for swells, winds and currents, and when the floating support pivots around the reel under the effect of the swell and / or the wind or sea current, most of the movements are generally limited to a substantially constant angular sector, for example limited between north and south-west. Said rotational guide elements then undergo alternating forces localized even more inhomogeneously along the periphery of the drum for this additional reason, resulting in increased or accelerated localized wear of said rotational guide elements.

The object of the present invention is to provide a floating support anchored on a reel and an improved bottom-to-surface connection installation which makes it possible to solve the above problems.

More particularly, the aim of the present invention is to provide

K a floating support anchored to a reel and an improved fund-surface connection installation which allow better distribution of the forces generated and transferred by the flexible pipes to the reel, in particular transferred to the periphery of the reel at the level of rotating guide elements undergoing vertical forces , so that said forces are distributed more regularly, more symmetrically and / or more evenly in intensity along the periphery of the reel.

To do this, the present invention provides a guide structure and flexible pipe offset within said reel.

More specifically, the present invention provides a floating support for oil production supporting or able to support bottom-to-surface connection conduits between a plurality of subsea conduits resting on the seabed and said support floating on the surface, said floating support comprising a reel comprising a cavity at least partly submerged within a structure offset in front of the floating support or integrated in or below the hull of the floating support, preferably passing through the hull of the floating support over its entire height, said reel comprising a cylindrical internal structure within said cavity, preferably of circular section, said internal structure comprising a tubular side wall surmounted at its upper end by an upper platform arriving substantially at the level of the deck of the floating support, said tubular side wall being at least partially closed at its lower end by a bottom wall, said stru cylindrical internal structure being traversed or capable of being traversed by a plurality of first flexible conduits connected to said upper platform and extending below said bottom wall to underwater conduits resting on the seabed or up to second pipes themselves connected to underwater pipes resting on the seabed, said cylindrical internal structure being articulated in rotation with respect to said cavity and said hull by means of rotating guide elements, preferably at least one rolling or friction bearing, so as to allow the rotation of said floating support about an axis

K substantially vertical ZZ 'of the cavity of said drum, without causing the rotation of part of said drum with respect to the same vertical axis ZZ', characterized in that said cylindrical internal structure comprises at least one, preferably a plurality of pipes of guide and offset, preferably rigid, containing and guiding or able to contain and guide a said first flexible pipe, said guide pipe passing through said bottom wall and non-vertically crossing the interior of said internal cylindrical structure of the reel between:

- On the one hand, said bottom wall at a first location C1 of said bottom wall where said guide pipe is fixed, said first location being preferably disposed at the periphery of said bottom wall, and

- on the other hand, an internal platform integral with said internal cylindrical structure above said bottom wall and above the level of the surface of the water, the upper end of said guide pipe being fixed to said internal platform at a second location C2 where the upper end of said flexible pipe contained in said guide pipe is fixed or is capable of being fixed, said second location being not vertically aligned with said first location, said second location being preferably disposed at the periphery of said internal platform.

It is understood that said flexible pipe passes through said bottom wall passing inside the guide pipe, without said flexible pipe being secured to said bottom wall.

In one embodiment, the upper end of said flexible pipe is attached to a connecting element which is itself attached to a said second location C2 where said upper end of said first flexible pipe is connected.

Due to the fact that the flexible pipes are not connected at the level of the bottom wall but only guided and retained laterally, and possibly in friction with the wall of said guide pipe, in particular at the level of its passage through the bottom wall, the 'essential of the vertical forces generated by said flexible pipes are transferred to the level of said internal platform where they can be connected at said second locations according to different arrangements than those of the first locations at said bottom wall and in particular therefore in such a manner to be able to transfer the forces generated by said first flexible pipes in a more regular and / or more symmetrical distribution at the level of said second locations than at the level of said first locations, in particular on the periphery of said internal facing platform said rotating guide elements.

We understand in other words that:

- Said first flexible pipes run through said cylindrical internal structure of the reel between said first locations and second locations arranged differently angularly, preferably in curved S-shaped shapes in projection in a vertical plane, or in the form of a left S-shaped curve in space , or substantially rectilinear in shape but inclined with respect to the vertical, and

- the forces transmitted by said upper ends of said first flexible pipes and taken up at said internal platform are distributed more homogeneously and / or more symmetrically around the periphery of the periphery of said internal platform than the forces transmitted by said first pipes flexible and which would be taken up by the bottom wall at said first locations if said first flexible pipes were fixed there.

By arrangement at the periphery, it is meant that said locations are located closer to the circumference than to the center of said bottom wall or and respectively said internal platform, preferably as close as possible to the periphery, therefore to the rotation bearings, without affect its solidity.

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More particularly, said first locations are arranged in a non-regular and / or non-symmetrical distribution along the periphery of said bottom wall.

More particularly, the number of said non-vertical guide pipes according to the invention will be from 1 to 100, preferably from 5 to 30.

More particularly still, said non-vertical guide pipe produces between said first location C1 and said second location C2 a deviation by an angle α of at least 5 ° in a horizontal plane between (a) a first vertical plane passing through the vertical axis ZZ 'of said internal cylindrical structure and the center of said first location C1 and (b) a second vertical plane passing through the vertical axis of said internal cylindrical structure and the center of said second location C2.

This value of a ~ 5 ° aims to mark the difference between a so-called non-vertical guide pipe according to the invention and a simple defect of verticality of a vertical guide pipe of the I-tube type known to those skilled in the art. art in the field of offshore oil industry.

More particularly still, said non-vertical guide pipe produces between said first location C1 and said second location C2 a deviation by an angle β of at least 5 ° in a vertical plane between (a) the vertical line passing through the center of said first location C1 and (b) the inclined line D passing through the two centers of said first and second locations C1, C2.

This value of β ~ 5 ° aims to mark the difference between a so-called non-vertical guide pipe according to the invention and a simple defect in verticality of a vertical guide pipe of the I-tube type.

Preferably, the floating support according to the invention comprises a plurality of said non-vertical guide pipes, said second locations C2 of which are arranged at the periphery of said circular internal platform in a more regular arrangement, preferably in an arrangement of said second successive locations the radial directions of which are angularly spaced at the same angle (gamma), and / or in a more symmetrical arrangement with respect to a diametral plane LL than said first locations C1 arranged at the periphery of said circular bottom wall.

More particularly still, said drum supports said first flexible pipes, at least part of said first flexible pipes passing through said non-vertical guide pipes arranged at said second locations so that the forces generated by said first pipes hoses are transferred and taken up in a substantially more homogeneous and / or more symmetrical manner along the periphery of the periphery of said internal platform than the forces generated by said first pipes at said first locations.

More particularly still, said first pipes are arranged at said second locations so that the forces generated by said first pipes are distributed in a substantially homogeneous and / or symmetrical manner around the periphery of the periphery of said internal platform, preferably said second locations being arranged substantially homogeneously and / or symmetrically around the periphery of the periphery of said internal platform.

In a preferred variant, said drum comprises at least one said guide ducts extending from a said first location at the level of said bottom wall to a said second location at the level of said internal platform in a substantially homogeneous manner and / or symmetrical around the periphery of the periphery of said internal platform, along a curved path in the form of S.

An S-shape is understood here to mean a shape curved in a plane with a single point of inflection of curvature, or else a left S-shape in three-dimensional space.

More particularly, when the guide pipe is curved, the axis of the pipe is not contained in a vertical plane.

In another variant embodiment, said reel comprises at least one said guide pipe extending from a said first location at the level of said bottom wall to a said second location at the level of said internal platform, along a path substantially inclined rectilinear (β).

More particularly still, said floating support comprises:

- a said upper platform supporting at least a first part of a rotary joint connector disposed axially ZZ 'above said internal platform,

- Said upper platform resting on first rotational guide elements, preferably a first rolling bearing, and supporting a first part of said rotating connection, said first part of said rotating connection being integral with said upper platform, driving elements of elbow joint connecting the upper ends of said first flexible pipes at said internal platform to said first part of said fitting, a second rotating part of said swivel fitting being supported by the bridge of the floating support, and

- a said sealed cylindrical internal structure, preferably with a circular section along said vertical axis ZZ ’, comprising a bottom wall assembled in a sealed manner to the lower end of a lateral tubular wall of said internal tubular structure, and

- a lower mooring structure, preferably of annular shape coaxial with said internal cylindrical structure, connected to said bottom wall, in front of said bottom wall, anchoring lines extending from said lower structure of mooring where they are moored to the bottom of the sea and said first flexible pipes passing through said lower mooring structure.

More particularly still, said drum comprises:

a said upper platform resting on a first rolling bearing arranged at a step at the upper end of said cavity, preferably so that said upper platform does not exceed in height the level of the support bridge floating, and

said lateral tubular wall with circular section of said cylindrical tubular internal structure cooperates with at least second and third lateral rolling or friction bearings, preferably rolling bearings, interposed between the cylindrical lateral wall of said cavity and said tubular wall side of said cylindrical internal structure and allowing rotation of said internal structure, said third rolling or friction bearing being located below said second lateral bearing, said second bearing preferably being above the surface of the water, close to the level of said internal platform, said third lateral bearing being located near the level of said bottom wall.

It is understood that, in this embodiment:

- Said cylindrical internal structure is articulated in rotation with respect to said cavity and said shell by means of said rotational guide elements, preferably at least one rolling or friction bearing, so as to allow rotation of said floating support around a substantially vertical axis ZZ 'of the cavity of said reel, without causing the rotation of said cylindrical internal structure of said reel relative to the same vertical axis ZZ', said mooring lines and first flexible pipes extending below the reel being able to remain fixed in rotation around the axis ZZ 'relative to the seabed, when said floating support is driven in rotation around the vertical axis ZZ' of said internal cylindrical structure or said drum cavity, and

- Said first part of the swivel joint cooperates in a sealed manner with the second part of the swivel joint so as to ensure the transfers of fluid or electric currents from or to the hoses and electric cables, while allowing the rotation of said floating support (and of said second part of the rotating union) around a substantially vertical axis ZZ 'of the cavity of said reel, without driving

VL the rotation of said first flexible pipes inside said cylindrical internal structure with respect to the same vertical axis ZZ.

More particularly still, the said rolling bearing (s) is (are) constituted by rollers or rollers guided in the rolling tracks, said rolling tracks and said rollers or rollers being arranged circularly around said internal structure, preferably regularly spaced.

The present invention also provides a bottom-to-surface connection installation comprising a floating support according to the invention characterized in that it further comprises at least one second rigid pipe providing the connection between the lower end of a said first flexible pipe. extending below said reel and the end of a submarine pipe resting on the seabed.

In an alternative embodiment, said second rigid pipe is arranged in a riser substantially vertically, said first flexible pipe to which it is connected taking the form of a double plunging chain.

In another variant embodiment, said second rigid pipe is of the type referred to as SCR, extending in a form of so-called single chain curve between the end of a pipe resting on the seabed and the lower end of a said first flexible pipe opening out below said drum and in continuity of curvature of said first flexible pipe.

Other characteristics and advantages of the present invention will emerge better in the light of the detailed description which follows, given in an illustrative and non-limiting manner, with reference to the drawings in which:

- Figure 1 is a side view of an FPSO 1 equipped with a reel 2 located in the front third of the hull, anchored in the and comprising bottom-surface connection pipes 4, 8 to pipes under -marines 9 resting at the bottom of the sea 10,

- Figure 2 is a cutaway and side view of a reel 2 integrated into the shell of an FPSO 1 according to the invention, detailing the path of an S-shaped guide pipe 5 according to the invention, a flexible pipe 4 from the bottom wall 2b of said reel 2, to an internal platform 6 located in the plane BB, at an upper level of said reel, said plane BB being disposed widely above the water level 11 added to the strongest swells, when said FPSO 1 is ballasted to the maximum,

- Figure 3 is a view detailing the connection of the upper end of the flexible pipes 4 at the level of connecting elements 6a fixed on the internal platform 6,

- Figure 4 is a representation of the type "rose wind" (in English "rose wind") of the distribution of vertical forces at the periphery of a reel, created by all the flexible pipes 4 connected to the latter, in a conventional configuration of the prior art,

- Figure 5A is a sectional view of a reel 2 according to the invention at the level of the plane AA of Figure 2, detailing the location of the various flexible conduits, umbilicals and electric cables 4, small 4c, medium 4b and large size 4a,

- Figure 5B is a section of the same reel according to the invention as that of Figure 5A, taken at the level of the plane BB of Figure 2, detailing the reorganization of the various flexible conduits, umbilicals and electric cables, small, medium and of large size, as well as the new "force rose" R 'resulting from this reorganization, said second locations of first flexible pipes being schematized in hatching when they are offset from said first locations, the latter being shown in dotted lines ; and

- Figure 6A is a vertical sectional view of the reel comprising a straight and inclined guide and offset pipe according to the invention 5 and a known vertical I-shaped guide pipe 5b, and

- Figure 6B is a horizontal sectional view along plane BB of the device of Figure 6A showing an offset of the guide pipe 5

VL according to the invention.

In Figure 1, there is shown in side view a floating support type "FPSO" 1 secured to a reel 2 located in the front third of said FPSO. Said reel 2 is anchored by a plurality of anchor lines 1a connected to anchors not shown planted in the underwater ground 10. The reel, known to those skilled in the art, is shown in section in FIG. 2 and has an internal cylindrical structure 2a which is substantially fixed in rotation about the axis ZZ relative to the seabed 10, inside a cavity 2d passing right through the hull ld of the floating support 1. The reel 2 is consisting of a tubular structure 2a sealed at its lower end by a bottom wall 2b and comprising at its upper end an upper platform 2c, of greater diameter than the lateral tubular wall 2a, said platform 2c coming to rest, in its peripheral parts protruding from the lateral tubular wall 2a, against the step at the upper end of the cavity 2d.

Said internal cylindrical structure 2a and the shell ld cooperate in relative rotation thanks to rolling bearings 2a2 and 2a3 comprising two upper lateral circular bearings 2a2 and lower 2a3 which transfer the horizontal forces between the drum and the structure of the FPSO and an upper circular supporting bearing bearing 2al which transfers all the vertical forces between the upper platform 2c of the reel and the bridge of the FPSO. This allows the FPSO to pivot freely around the vertical axis ZZ 'of the reel and to position itself in a direction corresponding to the result of the forces generated by the swell, the wind and the current on the FPSO and its superstructures, without the internal cylindrical structure 2a of the reel 2 does not pivot, the latter thus remaining substantially fixed in rotation about the axis ZZ ', vis-à-vis the seabed 10.

Said bearings 2a1, 2a2, 2a3 are friction or rolling bearings, preferably rolling bearings. It may more particularly be rollers or casters interposed between:

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- the internal wall of the cavity 2d and the external surface of the lateral tubular wall 2a, as regards the rollers or the lateral guide rollers 2a2 and 2a3, and

- The horizontal surface of the step and the underside of the upper platform 2c of the reel 2, with regard to the support bearing 2al.

It will be understood that at at least said bearings, said tubular structure 2 and said internal cavity wall 2d have a circular section. The rollers or casters of the lower and upper lateral guide bearings 2a2 and 2a3 are more particularly arranged with their axes of rotation in a vertical position. In the case of the upper support bearing 2al, said rollers or casters are arranged with their axes of rotation in a horizontal position resting on the step, the platform 2d resting on the edge of said rollers 2al.

In Figures 1 and 2, there is also shown the lower mooring structure 2-1 fixed on the underside of the bottom wall 2b and on which are fixed the anchor lines. The lower structure 2-1 has an annular shape and is crossed at its center by a plurality of said first flexible pipes including production pipes but also umbilicals and electric cables 4 of various sizes, light 4c, medium 4b and heavy 4a. which pass through the bottom wall passing inside the ends 5a of supported guide pipes 5 and passing through the bottom wall 2b then rising inside the sealed cylindrical structure 2a guided by non-vertical guide pipes 5 according to the invention and for some in vertical guide conduits 5b of the prior art. The upper ends 4-3 of first flexible pipes 4, emerging from the upper ends 5c of the guide pipes passing through the internal platform 6, are connected to connecting elements 6a supported by an internal platform 6 fixed inside and at the top of said internal structure 2 below the rotary joint connection 3, the lower part 3-2 being supported axially by the upper platform 2c of the internal cylindrical structure 2a. Finally, bent junction pipes 7 provide the junction of the upper ends 4-3 of the first flexible pipes.

K between the internal platform 6 and the swivel joint connection 3-2.

In shallow sea, that is to say when the water depth is 200 to 750, or even 1000m, the bottom-to-surface connection pipes, as well as the pipes 9 resting on the seabed are generally flexible pipes, such as pipes manufactured for the petroleum industry by Technip (France) or Wellstream (USA). On the other hand, when the water depth exceeds 1000-1500m, it is preferable to install, for the production or injection pipes of water or gas, second rigid steel pipes 8, insulated or not, between the underwater pipes 9 resting at the bottom of the sea and said first flexible pipes opening out in the subsurface below the reel of the FPSO. It is possible to have a second rigid pipe 8 connecting the sea bed to the end of a first flexible pipe 4 at the level of a float 12 at a distance below sea level of the order of 50 at 100m. Said second rigid pipe 8 may be vertical (not shown) or of the SCR ("steel catenary riser") type in the form of a so-called chain curve, with characteristics generally equivalent to those of production pipes, the connection with the FPSO then being ensured by the first flexible pipes in configuration of double plunging chain 4-2. When the water depth is greater than 1000m, the use of first flexible pipes of great lengths, extremely expensive, is avoided, and the rigid pipe 9 resting on the ground is advantageously extended to the FPSO in a simple chain configuration. or “SCR” as shown in FIG. 1, the upper part of the bottom-surface connection can then be formed by a flexible pipe portion 4-1, providing a flexible connection with the reel 2 of the FPSO, said first pipe portion flexible 4 then being in continuity of curvature with the upper end of the second rigid pipe 8 of SCR type and preferably of the same internal diameter, and of a total length, for example, from 50 to 100m. In such a configuration, the forces generated by the bottom-to-surface connection pipe 4, 8 on the reel are very important because of the height of the water section which in this case must be greater than 750-1000m.

In certain field configurations, there will be found in the lower part of the reel a concentration of flexible pipes of large diameter 4a, therefore of significant linear weight, arriving on a small area of the periphery of the reel, while in another area of the periphery of the reel. diametrically opposed position, there will be only flexible pipes or cables of low linear weight, or even no pipe in some cases arriving at the reel. FIG. 4 illustrates the effects of this case in an embodiment according to the prior art when the first flexible pipes 4 are connected to the bottom wall and the forces are essentially taken up and transferred by said bottom wall of the reel. We observe here:

- on the left, 4 flexible pipes of type 4a of large diameter, therefore of significant linear weight, therefore generating significant tensions and vertical forces,

- on the right a single flexible pipe of large diameter 4a,

- Then, distributed all around the periphery of the reel, a plurality of medium flexible pipes 4b, as well as small flexible pipes 4c.

The self-weight of the structure of the reel as well as the vertical forces due to the anchoring 1a are distributed substantially uniformly over the periphery of the reel, therefore the rotational guide elements 2al as well as the running tracks integral with the FPSO and the reel respectively , are substantially all constrained uniformly by these vertical forces. On the other hand, the irregular and / or asymmetrical distribution of said flexible pipes 4 in suspension generates non-homogeneous vertical forces on the periphery of the reel creating variations in stresses which can be very significant. Thus, FIG. 4 shows the “rose of the vertical forces” R, similar to the “rose of the winds” known to those skilled in the art in the field of meteorology, to represent the variation of the vertical forces F per unit length on the periphery of said reel: F then represents the vertical force per unit length, for example per curvilinear meter of the circumference of the upper platform applied to the rotation bearing 2al resulting from the distribution of the various flexible pipes in said peripheral zone of the reel when these forces are taken up at the level of the bottom wall where the pipes are connected according to the prior art or are transferred vertically without modification of distribution to an upper platform where they are connected. Thus, in the left and lower parts of FIG. 4, due to the large concentration of heavy flexible pipes 4a and a plurality of medium 4b and small pipes 4c, the force rose R then presents, in the direction of the needles of one shows the following variation:

- from the bottom of the figure, an increasing value from a zero value until Rl, then a slightly decreasing value until R2 (Fl),

- then again an increasing value which reaches a maximum F ₂ between R3 and R4, and finally a decreasing value to zero from R4 to R5,

- a whole range is then observed with a value F substantially zero up to the top of said figure,

- then an area R6 where the stress rose has a low value F ₃ due to the presence of a medium flexible pipe 4b,

- then again an area where F has a substantially zero value,

- up to the right zone of the figure where the presence of a plurality of flexible pipes of various sizes induces the rose of the forces R7,

- then again an area where F has a substantially zero value,

- then an area where the force rose R8 has a low value due to the presence of a single medium flexible pipe,

- finally an area where F has a substantially zero value.

Thus, when the FPSO 1 pivots around its reel 2 which is substantially fixed relative to the seabed 10, the rolling tracks as well as the rotation bearings 2al, 2a2, 2a3 are permanently subjected to vertical forces (2a) and lower horizontals (2a2 and 2a3) which vary from a zero value to a maximum value as explained

Ifrlz previously, which induces localized fatigue all the more important as the ranges of angular variations of the FPSO are often reduced to a limited sector, for example from the 260 ° bearing to the 325 ° bearing, corresponding for example to 90% of the time when the result of the effects of swell, wind and currents on the FPSO, maintains the latter in this bearing range. Thus, rolling tracks and rotational bearings subjected to greater alternating forces in this angular sector, will exhibit accelerated wear and fatigue in this angular sector, while other sectors will hardly undergo any significant force, and therefore little stress. significant wear and almost zero fatigue, during the service life of the installation which generally reaches 20-25 years, or even more.

In order to limit the extreme values of the localized forces F and to smooth the shape of the “force rose” R on the periphery of the reel, according to the present invention, as shown in FIGS. 2, 5A, 5B and 6, a device is provided for non-vertical guidance of the flexible pipes within the reel which advantageously makes it possible to modify the distribution of the load transfer generated by said flexible pipes within the reel 2.

In Figure 2, there is shown in section a reel 2 of an FPSO 1 traversed from bottom to top by a rigid steel guide pipe 5 in the form of S. Said guide pipe 5 is equipped in the lower part of a trumpet-shaped chute 5a intended to prevent damage to the flexible pipe 4 which it contains and guides in the contact zone when it arrives in the lower end of the guide pipe. Said guide pipe 5 passes through the bottom wall 2b of the reel in a sealed manner at a first location centered at C1 on the periphery of the bottom wall. The upper part of said guide pipe 5 is secured 6b to an internal support platform 6 secured to the internal cylindrical structure 2a of the reel 2 in the plane BB above the surface of the sea water and below the upper platform 2c of the reel. Said internal platform 6 also supports the upper end of said first flexible pipe contained in said guide pipe equipped with a connecting element 6a opening out to the outside of the guide pipe. The internal platform 6 supports all of said first flexible pipes, and therefore substantially all of the vertical forces of each of said flexible pipes.

The upper end of said pipe 4 is connected via a connecting pipe element 7 to a part 3-2 of the rotary joint connector 3. Said part 3-2 of the connector 3 is integral with the reel, therefore substantially fixed in rotation by relative to the seabed. Then, the fluid leaves part 3-1 of the connector 3 integral with the deck lb and the upper platform 2c, via a pipe 13. Part 3-1 of the rotating joint connector 3 is integral of the bridge of the FPSO 1 and is therefore in free rotation around the axis ZZ 'of the reel 2 with respect to part 3-2 integral with the reel 2. The same applies to the other flexible pipes 4b and 4c connected to the rotating joint at 3-2 via junction elements 7 and emerging at 3-1 towards pipes 13 on the bridge lb.

There is shown in Figure 5A, which corresponds to a sectional top view of the section of the plane AA of Figure 2, all the flexible pipes 4, 4a, 4b, 4c which are not connected at the level of the bottom wall but are contained and guided in guide pipes which pass through the bottom wall 2b at first locations centered in C1 according to a distribution imposed by the architecture of the field as explained previously with reference to Figure 4. Vertical forces are substantially completely transferred to the level of the internal platform 6 where the pipes are in suspension.

In this figure 5A, there is shown four guide and offset pipes 5 according to the invention for heavy flexible pipes 4a-2 to 4a-5, as well as two guide and offset pipes 5 for medium flexible pipes 4b-l and 4b-2 and a plurality of other conventional substantially vertical guide conduits for medium and small flexible conduits, distributed over the periphery. In figs 5A-5B, said guide pipes of the flexible pipes 4a-2 to 4a-5 are S-shaped guide pipes according to the invention, while the other guide pipes, and in particular the guide pipe of the flexible pipe 4a-1 are conventional pipes of the I-pipe type (in English I-tube) known to those skilled in the art in the field of offshore oil exploitation, and represented 5b in FIG. 1.

In FIG. 5B, there is shown the position of the upper ends 5c of the guide pipes 5 of the same flexible pipes 4a-2 to 4a-5 fixed 6b on the periphery of the platform 6 at second locations centered at C2. The heavy flexible pipe 4a-1 is located substantially at the same position at the head as at the foot (FIG. 5A), and its guide pipe is of the I-tube type, substantially vertical. The flexible pipes 4a-2 to 4a-5 are offset thanks to the S-shaped guide pipes according to the invention and are then advantageously distributed evenly around the periphery, substantially every 60 ° (Y *) along the axes LL - MM - NN, and substantially symmetrically with respect to LL. The respective offset of the second locations C2 relative to the first locations C1 is represented by an arrow in this FIG. 5B and corresponds to an angle a2 to a5 greater than 5 °, in particular here from 10 to 60 °, in a horizontal plane between the planes. substantially vertical radials containing the ZZ 'axis and passing through Cl and C2 respectively. The two medium flexible pipes 4b-1 and 4b-2 are brought closer to each other thanks to two S-shaped guide pipes, substantially symmetrically with respect to the axis LL, and creating a minor offset of the order of 5 to 8 °.

Thus, most of the heavy loads are regularly and symmetrically distributed around the periphery of the platform 6 and therefore regularly and symmetrically transferred and taken up at the level of the bearing 2al with a slight peak of force approximately every 60 °, without creating any significant stress variations on the reel, shell and rolling bearings. When the FPSO 1 moves around its reel 2, which is substantially fixed with respect to the seabed, this will result in a drastically reduced level of stress and local fatigue, as well as a substantially uniform overall fatigue on the rolling elements and especially on the the rolling tracks, over the entire periphery of the reel. The result is thus a better behavior of the entire fund-surface installation throughout the life of the installation, the latter being commonly 15 to 20 years, or even more, without requiring heavy maintenance, such as dry docking for disassembly and change of these very critical components and subject to wear, which is commonly observed in the prior art.

In FIGS. 6A-6B, an exemplary embodiment of a non-vertical guide pipe 5 according to the invention having a rectilinear shape D inclined at an angle β greater than 5 ° relative to the vertical is shown by way of illustration, here about 30 °, over a height H between the bottom wall 2b and the internal platform 6 of at least 75% of the height of the reel, ie H = 10 to 20m. This results in an offset from said second location by an angle alpha of 175 °, as shown in FIG. 6B, in a horizontal plane between the radial planes containing the axis ZZ 'and passing respectively through C1 and through C2. Rather than straight guide pipes according to the invention, it is preferred to implement S-shaped guide pipes in a plane or in three-dimensional space, because it is thus easier to have a greater number of pipes of guidance in the interior of the reel without risking interference between said pipes 5, or even congested areas thereby limiting the possibilities of access for inspection and maintenance.

For example, an FPSO reel completely crosses the hull of the floating support over a height of 30 to 55m in height, its diameter is 10 to 25 m, in particular 12 to 16m, and its own weight is approximately 2 500 to 5,000 tons. All the vertical forces due to the bottom-surface connection pipes can reach 5,000 to 7,500 tonnes or even 10,000 tonnes. Large flexible pipes in great depths of water can each generate forces of 100 to 250 tonnes, in the case of 4-2 chains as described with reference to figure 1, in the case of rigid pipes in the SCR 8 configuration , 4-1, the vertical forces can reach 750 tonnes to 1000 tonnes, or even more, for each line.

K

It is thus possible to install a large number of pipes, gas, raw products, hydraulic umbilicals and electric cables 4a-4c, for example 36 or 48 flexible pipes 4, whatever the architecture of the field and the location of the cables. various wellheads around the FPSO.

Claims (15)

1. Floating support (1) for oil production supporting or capable of supporting bottom-to-surface connection pipes between a plurality of underwater pipes (9) resting on the seabed (10) and said floating support (1) in surface (11), said floating support comprising a reel (2) comprising a cavity (2d) at least partly submerged within a structure offset in front of the floating support or integrated in or below the hull of the floating support, preferably passing through the shell of the floating support over its entire height, said reel (2) comprising a cylindrical internal structure (2a) within said cavity, preferably of circular section, said internal structure comprising a tubular side wall surmounted at its end upper of an upper platform (2c) arriving substantially at the level of the deck (lb) of the floating support, said tubular side wall (2a) being at least partially closed at its lower end by a bottom wall (2b), said cylindrical internal structure being traversed or capable of being traversed by a plurality of first flexible conduits (4, 4a-4c) connected (7) to said upper platform (2c) and extending below said bottom wall (2b) up to to submarine pipes (9) lying on the seabed or to second pipes (8) themselves connected to submarine pipes (9) lying on the seabed, said cylindrical internal structure ( 2a) being articulated in rotation with respect to said cavity (2d) and said shell by means of rotating guide elements, preferably at least one rolling or friction bearing (2ai, 2a2, 2a3), so to allow the rotation of said floating support around a substantially vertical axis ZZ 'of the cavity of said drum, without causing the rotation of part of said drum with respect to the same vertical axis ZZ', characterized in that said cylindrical internal structure ( 2a) comprises at least one, preferably one pl urality of guide and offset conduits (5), preferably rigid, containing and guiding or able to contain and guide a said first flexible conduit (4), said guide conduit (5) passing through said bottom wall (2b) and non vertically crossing the interior of said internal cylindrical structure (2a) of the reel between: - on the one hand, said bottom wall (2b) at a first location (Cl) of said bottom wall where said guide pipe is 5 is fixed, said first location preferably being disposed at the periphery of said bottom wall, and - on the other hand, an internal platform (6) integral with said internal cylindrical structure (2a) above said bottom wall and above the level of the water surface (11), the upper end (5c) ) from Said guide pipe (5) being fixed (6b) to said internal platform (6) at a second location (C2) where is fixed or is able to be fixed the upper end (4-3) of said flexible pipe (4) contained in said guide pipe, said second location being not vertically aligned with said first location, said second location preferably being disposed at the periphery of said internal platform (6). 2. A floating support according to claim 1, characterized in that said first locations are arranged in a non-regular and / or non-symmetrical distribution along the periphery of said wall of 20 background. 3. A floating support according to claim 1 or 2, characterized in that said non-vertical guide pipe (5) produces between said first location (C1) and said second location (C2) a deviation by an angle alpha of at least 5 ° in a horizontal plane between (a) a first 25 vertical plane passing through the vertical axis (ZZ ') of said internal cylindrical structure and the center of said first location (C1) and (b) a second vertical plane passing through the vertical axis of said internal cylindrical structure and the center of said second location (C2). 4. A floating support according to claim 1, 2 or 3, characterized in that said non-vertical guide pipe (5) produces between said first location (C1) and said second location (C2) a deviation by an angle β d. 'at least 5 ° in a vertical plane between (a) the vertical line K passing through the center of said first location (Cl) and (b) the inclined line (D) passing through the two centers of said first and second locations (Cl, C2). 5. floating support according to one of claims 1 to 3, characterized 5 in that it comprises a plurality of said non-vertical guide pipes (5), said second locations (C2) of which are arranged at the periphery of said circular internal platform (6) in a more regular arrangement, preferably in an arrangement of said second successive locations whose radial directions are angularly spaced by the same angle (gamma), and / or in a more symmetrical arrangement with respect to a diametral plane (LL) than said first locations (C1) arranged at the periphery of said circular bottom wall. 6. floating support according to one of claims 1 to 5, characterized 15 in that it supports said first flexible pipes (4), at least part of said first flexible pipes passing through said non-vertical guide pipes arranged at said second locations so that the forces generated by said first flexible pipes are transferred and taken up again 20 substantially more homogeneous and / or more symmetrical along the periphery of the periphery of said internal platform than the forces generated by said first pipes at said first locations. 7. A floating support according to claim 6, characterized in that said first pipes are arranged at the level of said second 25 locations so that the forces generated by said first pipes are distributed in a substantially homogeneous and / or symmetrical manner around the periphery of the periphery of said internal platform (6), preferably said second locations being arranged in a substantially homogeneous manner and / or symmetrical around the periphery of the periphery of said internal platform. 8. A floating support according to one of claims 1 to 7, characterized in that it comprises at least one said guide pipes extending § U from a said first location at the level of said bottom wall to a said second location at the level of said internal platform in a substantially homogeneous and / or symmetrical manner around the periphery of the periphery of said internal platform, along a curved path in the form of an S. 9. A floating support according to one of claims 1 to 8, characterized in that it comprises at least one said guide pipes extending from a said first location at the level of said bottom wall to a said second location. at said platform 10 internal, along a substantially rectilinear inclined path (β). 10. Floating support according to one of claims 1 to 9, characterized in that: - Said upper platform (2c) supports at least a first part (3-1) of a rotary joint connection (3) disposed axially (ZZ ') at the- 15 above said internal platform (6), - said upper platform (2c) resting on first rotational guide elements, preferably a first rolling bearing (2i), and supporting a first part (3-1) of said rotating union (3), said first part (3) -1) of said rotary union being 20 integral with said upper platform (2c), elbow junction pipe elements (7) connecting the upper ends (4-3) of said first flexible pipes at said internal platform (6) said first part (3-1) ) of said connector, a second rotating part (3-2) of said rotating connector being supported by the bridge (le) of the floating support, and - a said sealed cylindrical internal structure (2, 2a), preferably with a circular section along said vertical axis (ZZ '), comprising a bottom wall (2c) assembled in a sealed manner to the lower end of a lateral tubular wall of said internal structure 30 tubular, and - a lower mooring structure (2-1), preferably of annular shape coaxial with said cylindrical internal structure, connected to said VrL * Bottom wall, in front of said bottom wall, anchoring lines (la) extending from said lower mooring structure (2-1) where they are moored to the bottom of the sea and said first flexible pipes (4) passing through said lower mooring structure. 11. Support according to claim 10, characterized in that: - Said upper platform (2c) bears on a first rolling bearing (2ai) arranged at a step (le) at the upper end of said cavity (2d), preferably so that said platform upper (2c) does not exceed in height the level of the deck (le) of the floating support, and - Said lateral tubular wall of circular section of said cylindrical tubular internal structure cooperates with at least second and third lateral rolling or friction bearings, preferably rolling bearings (2a2, 2a3), interposed between the cylindrical side wall of said cavity (2d) and said side tubular wall of said internal cylindrical structure and allowing rotation of said internal structure, said third rolling or friction bearing (23) being located below said second side bearing (22), said second bearing being preferably above the surface of the water, near the level of said internal platform, said third lateral bearing being located near the level of said bottom wall. 12. Floating support according to one of claims 1 to 11, characterized in that the said rolling bearing (s) is (are) constituted by rollers or rollers guided in tracks. rolling, said rolling tracks and said rollers or rollers being arranged circularly around said internal structure, preferably regularly spaced. 13. Bottom-surface connection installation comprising a floating support (10) according to one of claims 1 to 12, characterized in that it further comprises at least one second rigid pipe (8) providing the connection between the end. lower of a said first pipe Ή ♦ * flexible extending below said reel and the end of a submarine pipe resting on the seabed. 14. Bottom-surface connection installation according to claim 13, characterized in that said second rigid pipe (8) is arranged in a riser substantially vertically, said first flexible pipe to which it is connected taking the form of a double plunging chain (4). -2). 15. Bottom-to-surface connection installation according to claim 13, characterized in that said second rigid pipe (8) is of the type called SCR, extending in a form of so-called single chain curve between the end of a pipe. resting on the seabed (9) and the lower end of said first flexible pipe opening out below said drum and in continuity of curvature of said first flexible pipe (4-1).