EP0897455B1 - Manifold support mounting plate for oil extracting installation and method of installation - Google Patents

Description

The present invention relates to petroleum exploitation off-shore, and more particularly an operating installation petroleum using flexible pipes for the transport of pressurized fluids such as hydrocarbons from overheads subsea wells.

The pipes used for the transport of hydrocarbons can clog and clog up after training a deposit on the internal surface of the pipes, which happens frequently when oil has a high level of paraffin.

In this case, cleaning can be carried out periodically. conduits, also called "pigging", by exerting an action mechanical on the internal surface of the pipes.

In order to carry out this cleaning operation, we isolate submarine wellheads of flexible pipe sections used to transport oil to the surface and we connect these flexible pipe sections together so as to form a loop for injecting from an operating installation on the surface, a cleaning device at one end of the loop and to retrieve this cleaning device at the other end of the loop.

To make it easier to isolate wellheads submarines of flexible pipe sections used for the transport of hydrocarbons to the surface, it is known to dispose the connection manifolds for establishing a tight connection between short length and small diameter pipes from wellheads and large flexible pipe sections length and larger diameter used for transportation to the surface on pedestals resting on the seabed.

The use of such bases facilitates the connection of pipes of different diameters, for example the connection between a 15.2cm (6 ") internal diameter flexible pipe and a 10.2cm (4") pipe internal diameter, to the extent that it would be difficult incorporate a manifold for this purpose on the wellhead itself given its structure.

These bases can also support the valves allowing to isolate the well heads and to communicate the different sections of flexible pipe together to form the loop necessary for the cleaning operation.

To connect, during the cleaning operation, two flexible pipe sections used during operation for transport the hydrocarbons from the respective well heads up to the surface operating facility, we proposed use a base supporting a rigid U-shaped connection, connected at its ends with two sections of flexible pipe.

The U-shaped connector is isolated by a valve when the exploitation of wells so that the hydrocarbons produced by each wellhead traverses two sections of pipe separate flexible up to the surface operating installation; to carry out the cleaning, each well head is isolated and connects the two sections of flexible pipe through the connector in U, which makes it possible to constitute a loop allowing the passage, in the two flexible pipe sections, a cleaning.

However, the use of a base supporting a fitting U-shaped connected to two juxtaposed flexible pipe sections makes delicate and costly installation, insofar as one of the two flexible pipe sections is connected to a second base which must be launched while simultaneously managing the course in chain of the two flexible pipe sections.

A second solution would consist in placing on the bottom the bases and perform in situ connection of pipes flexible on manifolds.

However, such a solution is not easy to implement. work since it is difficult to move horizontally elements to be assembled on the seabed.

The object of the invention is in particular to make the installation of an oil exploitation installation comprising manifold support bases connected to pipe sections flexible.

According to a characteristic of the invention, the installation oil exploitation has two bases resting on the bottom submarine, each base supporting a manifold connected to two ends with two end pieces of flexible pipe sections respective, fixed to the manifold substantially in the extension one on the other, each manifold further comprising a flange for the tight connection to a pipe coming from a structure underwater such as an underwater wellhead, manifolds of two bases being connected together at one end by a section of flexible pipe and connected at the other end, by sections of respective flexible pipe, to an operating installation in area.

It should be understood that the end caps of sections of flexible pipe are attached to the manifold substantially in the extension of each other when the flexible pipe sections leave the base on which said manifold is fixed in substantially opposite directions.

Installation on the seabed of the installation can then be carried out without it being necessary to manage the simultaneous launching of two pipes flexible, because it is possible thanks to the invention to start with to put in the water a first section of flexible pipe, to put then with water a first base, then a second section of pipe flexible, a second base and finally a third section of pipe flexible.

Advantageously, the portions of the flexible pipes close to the end caps attached to the manifold can each slide in a curvature limiting member integral with said basement.

In a particular embodiment of the invention, said curvature limiting member is constituted by a set of vertebrae fixed at one end to said base and inside which can slide said flexible pipe portion close to the end piece terminal attached to the manifold.

Advantageously, said manifolds each have a shape general of T, said pipe connection flange coming from of the associated underwater structure being carried by the branch central T.

Advantageously, one of the two bases supports a valve used to communicate or isolate the manifolds located on the two bases.

Advantageously, the installation comprises a network of remote control lines for underwater organs such as valves, consisting of umbilical-type pipes, this network comprising a first umbilical connecting the surface operating installation to a first base and a second umbilical connecting the first base to second base.

• dérouler, à partir d'un point de départ, sur le fond sous-marin un premier tronçon de conduite flexible au moyen d'un navire de pose,
• mettre à l'eau un premier socle préalablement raccordé au premier tronçon et à un deuxième tronçon tout en déroulant le début du deuxième tronçon en même temps que la fin du premier,
• dérouler sur le fond ledit deuxième tronçon de conduite flexible,
• mettre à l'eau le deuxième socle préalablement raccordé au deuxième tronçon et à un troisième tronçon tout en déroulant le début du troisième tronçon en même temps que la fin du deuxième,
• dérouler sur le fond ledit troisième tronçon de conduite flexible, le navire de pose effectuant sensiblement une boucle lors de la pose des trois tronçons de conduite flexible entre ledit point de départ et un point d'arrivée.

The invention also relates to a method of installing an oil exploitation installation, this installation comprising two bases intended to rest on the seabed, each base supporting a manifold intended to be connected at two ends to two sections of respective flexible pipes fixed to the manifold substantially in the extension of one another, each manifold further comprising a flange for the sealed connection to a pipe coming from an underwater structure such as a wellhead, the manifolds being intended to be connected together at one end by a flexible pipe section and connected at the other end by respective flexible pipe sections to a surface operating installation, this method comprising the steps consisting in successively:

• unwind, from a starting point, on the seabed a first flexible pipe section by means of a laying vessel,
• launching a first base previously connected to the first section and to a second section while unrolling the start of the second section at the same time as the end of the first,
• unwind said second flexible pipe section on the bottom,
• launching the second base previously connected to the second section and to a third section while unrolling the start of the third section at the same time as the end of the second,
• unwind on the bottom said third section of flexible pipe, the laying vessel making a substantial loop during the laying of the three sections of flexible pipe between said starting point and an arrival point.

Advantageously, the launching of each base takes place while the base is connected by two cables to the vessel laying, a first cable being attached to the rear of the base and a second cable being attached to a rigid gantry articulated on the base, only the cable connected to the rear of the base used to support the base first of the descent, the tension in this cable being released when the base reaches a certain depth, the cable attached to the gantry then used to bring the base in a substantially horizontal position and then to hold it until its poses on the seabed.

Advantageously, the gantry is detachably fixed to the base so that it can be recovered after the installation of a base and be used to install the next base.

Advantageously, the gantry comprises at least one member rotary actuator to be operated by a robot manipulator, this rotary actuator being connected by a transmission to a mechanism capable of transforming the rotation of said organ in an unlocking movement of a hook for fixing the gantry on the base.

In addition, it has been proposed to make the connection between the subsea wellhead and the connection flange of the manifold carried by the base by means of a rigid pipe made tailor-made after an in situ observation of the orientations of said connection flange and a second connection flange provided on the wellhead and their relative position.

This procedure is relatively long and expensive.

To facilitate the connection between a structure underwater such as an underwater wellhead and the flange of connection provided on the manifold carried by the base, we suggest, according to the invention, a new manifold support base for a oil exploitation facility.

This new base is intended to rest on the bottom submarine and supports a manifold to establish a connection watertight between a pipe coming from an underwater structure such that an underwater wellhead and at least a terminal portion of at least minus one section of flexible pipe, the manifold comprising a connection flange to said pipe and the base and / or the manifold comprising means for orienting the axis of the flange of connection in a chosen direction before establishing the connection with said pipe when the base rests on the bottom submarine.

Such a base facilitates the laying of a pipe between the manifold provided on the base and the wellhead, insofar as it is no longer necessary to tailor a pipe and such base also makes it possible to install the installation on a background submarine with significant elevations while using pipes fitted with fittings comprising a locking member can come into locking position by the effect of gravity, in which case said aforementioned chosen direction corresponds to the vertical, with an angular tolerance less than or equal to 10 ° and preferably less than or equal to 5 °.

In a particular embodiment, the base includes a fixed frame intended to rest on the seabed and a tray orientable relative to the frame and on which said manifold is fixed.

In a particular embodiment, said plate is connected audit built by a cardan-type joint.

Advantageously, the base includes means allowing to orient and maintain in the chosen position said flange of connection.

Advantageously, the base further comprises means allowing the removable fixing on the base of a gantry used for installing and / or recovering the base.

• la figure 1 est une vue schématique d'une installation d'exploitation pétrolière conforme à un exemple de réalisation de l'invention,
• la figure 2 est une vue schématique en perspective d'un socle conforme à un exemple de réalisation de l'invention,
• la figure 3 est une vue en élévation latérale du socle représenté sur la figure 2, les conduites flexibles n'étant pas représentées,
• la figure 4 est une vue analogue à la figure 3, après mise en place des conduites flexibles et des boítes de raccordement des ombilicaux de commande,
• la figure 5 est une vue de dessus du socle représenté sur la figure 4,
• la figure 6 est une vue schématique de dessus du plateau de support du manifold porté par le bâti du socle représenté sur les figures 2 à 5,
• la figure 7 montre isolément un élément de l'articulation permettant d'orienter dans une position choisie le plateau représenté sur la figure 6,
• la figure 8 est une vue en coupe selon le trait de coupe VIII-VIII de la figure 6,
• la figure 9 est une section selon le trait de coupe IX-IX de la figure 6,
• la figure 10 est une section selon le trait de coupe X-X de la figure 6,
• la figure 11 est une vue schématique de dessus du manifold porté par le socle représenté sur la figure 2, des conduites flexibles seuls les embouts de raccordement étant représentés,
• la figure 12 est une vue schématique représentant un ensemble de vertèbres,
• la figure 13 est une vue schématique en élévation latérale représentant un portique utilisé pour la pose d'un socle,
• la figure 14 est une vue de dessus du portique représenté sur la figure 13,
• la figure 15 est une vue en élévation frontale du portique représenté sur la figure 13,
• la figure 16 représente un détail du mécanisme de fixation amovible du portique sur le socle,
• les figures 17 à 21 illustrent différentes étapes de la pose d'un socle et,
• la figure 22 illustre la pose d'une boíte de raccordement d'ombilicaux de commande sur un support de boíte de raccordement fixé sur un socle.

Other characteristics and advantages of the present invention will emerge on reading the detailed description which follows, of a non-limiting exemplary embodiment of the invention, and on examining the appended drawing in which:

• FIG. 1 is a schematic view of an oil exploitation installation according to an exemplary embodiment of the invention,
• FIG. 2 is a schematic perspective view of a base according to an exemplary embodiment of the invention,
• FIG. 3 is a side elevation view of the base shown in FIG. 2, the flexible pipes not being shown,
• FIG. 4 is a view similar to FIG. 3, after the flexible pipes and connection boxes for the control umbilicals have been put in place,
• FIG. 5 is a top view of the base shown in FIG. 4,
• FIG. 6 is a schematic top view of the support plate for the manifold carried by the base frame shown in FIGS. 2 to 5,
• FIG. 7 shows in isolation an element of the articulation making it possible to orient the plate shown in FIG. 6 in a chosen position,
• FIG. 8 is a sectional view along the section line VIII-VIII of FIG. 6,
• FIG. 9 is a section along the section line IX-IX in FIG. 6,
• FIG. 10 is a section along the section line XX of FIG. 6,
• FIG. 11 is a schematic view from above of the manifold carried by the base shown in FIG. 2, flexible pipes only the connection ends being represented,
• FIG. 12 is a schematic view showing a set of vertebrae,
• FIG. 13 is a schematic side elevation view representing a gantry used for the installation of a base,
• FIG. 14 is a top view of the gantry represented in FIG. 13,
• FIG. 15 is a front elevation view of the gantry represented in FIG. 13,
• FIG. 16 represents a detail of the removable fixing mechanism of the gantry on the base,
• FIGS. 17 to 21 illustrate different stages of the installation of a base and,
• FIG. 22 illustrates the fitting of a control umbilical connection box on a connection box support fixed on a base.

There is shown schematically in Figure 1 a installation 1 in accordance with a particular embodiment of the invention.

This installation 1 is intended for the operation of two 2.3 subsea oil well heads by a surface vessel 4 such as a dynamically positioned vessel.

In the example described, the difference in depth between the submarine well 2 and the submarine well 3 is of the order of 150 m, the average slope between the two wells being of the order of 7 °.

Installation 1 comprises a first pipe section 5 flexible to connect the vessel 4 to a manifold 10 supported by a first base 6, this manifold used to connect the head of submarine well 2 in said first section of flexible pipe 5.

A second flexible pipe section 7 connects the manifold 10 to a second manifold 10 'located on a second base 8.

A third flexible pipe section 9 connects the manifold 10 'located on the second base 8 and the ship 4.

The flexible pipe sections 5,7 and 9 present in the example of embodiment describes an internal diameter of 6 "and are of "flow line" type.

Each manifold 10, 10 'has a T-connector, which fitting carrying on its central branch a flange 11 for the tight connection to a pipe 12 coming from the wellhead 2, 3 associated with the base considered and constituted in the example described by a flexible pipe with an internal diameter of 10.2cm (4 "), this pipe 12 still being called "jumper".

Each T-connector is provided on its branch carrying the flange 11 of a valve 13 making it possible to isolate the pipe 12 for a cleaning operation of the pipe sections 5, 7 and 9 like this will be specified below.

The manifold 10 'supported by the base 8 comprises in in addition to a valve 14 making it possible to isolate the T-connector from the section of flexible pipe 7 during operation of well heads 2 and 3.

Note that the opposite connection flanges of each manifold 15 and 16 have substantially parallel axes, this which allows the respective end portions 17 and 18 of the sections flexible pipe 5 and 7 to be located substantially in the extension of each other.

The bases 6 and 8 also support boxes of connection of control umbilicals.

We must understand by the expression "umbilical command ", one or more information transport cables, electrical or hydraulic power.

More specifically, the base 6 supports two boxes of connection 22, 23 and the base 8 supports a connection box 24.

The connection box 22 makes it possible to connect a command umbilical 25 from ship 4, an umbilical of control 26 connected to the wellhead 2 and a control umbilical 27 connected to the connection box 23. The latter allows connect the control umbilical 27 and one end of an umbilical control 28 connected at the other end to the connection box 24. The connection box 23 is also connected by the umbilical control valve 13 for controlling the opening or closing of the latter. The connection box 24 allows connect the control umbilical 28, a control umbilical 29 from wellhead 3 and two control umbilicals respectively connected to valves 13, 14 for controlling their opening or closing.

The control umbilical 27 is permanently fixed to the base 6, and it is placed on the seabed simultaneously with the latter.

In FIG. 1, the whole part extending above the dotted line F rests on the bottom of the sea while the part below extends between the seabed and the ship 4.

An arch 30 is placed on the path of the sections of flexible pipe extending between the ship 4 and the seabed, the flexible pipe sections resting on this arch 30 according to a configuration known in itself and of the "lazy-S" type.

The flexible pipe sections 5 and 9 are formed on their portion extending between the seabed and the ship 4, by flexible pipes specially adapted for the ascent of hydrocarbons and of the "riser" type.

During the operation of well heads 2, 3, the valves 13 are open and the valve 14 is closed.

Pressurized hydrocarbons from the head of wells 2 are conveyed to the ship 4 by the flexible pipe section 5 while the hydrocarbons under pressure coming from the head of wells 3 are conveyed to the ship 4 by the flexible pipe section 9.

In the case where the hydrocarbons produced are rich in paraffin, a progressive clogging of the flexible pipe sections 5 and 9 occurs, forcing periodic cleaning of these last.

To do this, the valves 13 are closed so as to isolate the well heads 2 and 3 and the valve 14 is opened so as to join the pipe sections 5, 7 and 9 and form a loop allowing injection by one end of one of the sections 5 and 9 a cleaning device from the ship 4.

The cleaning device can comprise in known manner in itself a brush and / or any other scraping system.

There is shown in Figure 2 in perspective schematic, the base 6.

The base 8 is substantially identical to the base 6 to the exception is that it only carries a junction box support control umbilicals and it also carries valve 14. The base 6 has not been shown in detail in the drawing.

The base 6 comprises a frame 31, made of metal in the example described, and a manifold support plate 32, this plate 32 which can advantageously be oriented in a position chosen with respect to the frame 31 as will be explained below.

We distinguish in Figure 2 two supports 33 for receiving the connection boxes 22 and 23. Each support 33 is provided with guide rails 33 a for centering the connection box during its descent on the support and a guide 33 b for the introduction of a pin extending below the connection box. The guide 33 b has a flared opening in the upper part facilitating the introduction of the spindle.

The frame 31 has a generally flattened shape and rectangular.

There is shown in Figure 3, in side elevation, the base 6, the end portions of the flexible pipe sections not being illustrated in this figure.

There is shown in Figure 4, in side elevation, the base 6 when the terminal portions 17 and 18 of the sections of flexible pipe are fixed to the T-connector of manifold 10. Are also shown very schematically in Figure 4 the boxes 22 and 23 and the control umbilicals 25 and 28.

As indicated above, the plate 32 is orientable by compared to the frame 31. More precisely, in the example of embodiment described, the plate 32 is connected to the frame 31 by an articulation of cardan type allowing the plate 32 to oscillate around a first geometric axis of rotation X substantially parallel to the side larger dimension of the frame 31 and a second geometric axis of rotation Y, perpendicular and intersecting with the X axis. The intersection of the X and Y axes corresponds substantially to the center of gravity of the tray so that it can be adjusted in position relatively easily.

The articulation of the plate 32 on the frame 31 takes place at by means of a cross 33 ′, shown in isolation in FIG. 7, comprising a tube 34 of axis X and a tube 35 of axis Y fixed to the tube 34 by an assembly structure 36 located in the center of the cross.

Referring now more particularly to Figures 6 to 10, the plate 32 is integral on its underside a pin 37 of axis X, engaged in one end 38 of the tube 34 and can pivot in the latter around the geometric axis of rotation X.

The plate 32 is secured, on the opposite side, to a bearing 39 of axis X, being able to pivot around a pin 40 engaged in the end 41 of the tube 34 opposite the end 38. The pin 40 is immobilized in rotation in the tube 34, and it is integral with its opposite end to the tube 34 of a fork 42, having two parallel walls between which a nut 43 can pivot around an axis of rotation Z parallel to the axis X.

This nut 43 is engaged on a threaded rod 44 mounted at rotation on the plate 32 around a geometric axis of rotation K perpendicular and intersecting the Z axis.

The threaded rod 44 is provided at its upper end a wheel 45 shaped to be able to be actuated in rotation by a manipulator robot. The rotation of the threaded rod 44 causes the up or down the nut 43 and the rotational drive of the plateau around the geometric axis of rotation X since the journal 40 is fixed relative to the frame 31.

The tube 35 of the cross 33 'is rotatably mounted around the Y axis on the frame 31. More precisely, the tube 35 is mounted free rotating at one end 46 on the frame 31 by means of a pin 90 secured to the frame 31. The tube is secured to the other end a journal 91 rotatably supported by a bearing of the frame 31. The pin 91 is secured at its end opposite to that engaged in the tube 35 of a fork 47 comprising two branches bearing rotation about an axis parallel to the Y axis a nut 48 in engagement with a threaded rod 49 rotatably mounted on the frame 31 around a axis W substantially perpendicular to the plane of the frame 31. The threaded rod 49 is provided at its upper end with a shaped wheel 50 to be rotated by a manipulator robot. The rotation of the rod 49 causes the nut 48 to rise or fall and the pivoting of the plate 32 around the Y axis.

A spirit level 51 is fixed on the upper face of the plate 32 to allow positioning the plate 32 to the horizontal, with the axis H of the flange 11 substantially at the vertical, as shown in figure 6.

Thus, after the installation of the base 6 or 8, it is possible to change the orientation of the connection flange 11 before attach the fitting to the end of the driving 12.

When the seabed on which the base 6 is placed or 8 is inclined, we can thus position the joint plane of the flange 11 substantially horizontal, the axis H of the flange then being substantially vertical, to within the tolerances allowed for the connection to line 12. The latter is advantageously fitted with a connector comprising a locking member capable of come into the locking position by the effect of gravity, at which case it is particularly important that the joint plane of the flange 11 be as horizontal as possible. In the example of realization described, you can rotate the plate 32 by about 10 ° around each axis X and Y, and ensure the verticality of the axis H of the flange 11 with an angular tolerance better than 5 °, and preferably better than 3 °.

FIG. 11 shows the manifold 10 in view On top.

The connection ends of the end parts 17 and 18 of the flexible pipe sections 5 and 7.

The connection of the end pieces 52 and 53 and the flanges 15 and 16 is effected by means of seals 54 and 55 of a type known per se under the denomination "Grayloc".

To avoid excessive curvature of the portions terminals 17 and 18 of flexible pipe, the latter are engaged each in curvature limiting members constituted in the example described by a set 56 of vertebrae.

These vertebrae are not shown in Figure 11 for the sake of clarity of the drawing.

FIG. 12 shows a set 56 of vertebrae constituted by the assembly, in a manner known per se, of vertebrae 57 and 58 having a symmetrical shape of revolution and constituted by tubular elements having in section in a plane containing their axis of symmetry, a U shape with turned edges inward for vertebrae 57 or with edges facing the exterior for the vertebrae 58, the assembly of two vertebrae 58 performed by means of a vertebra 57.

The terminal portion of each pipe section flexible engaged in a set of vertebrae 56 is free from slide inside of it. Each set of 56 vertebrae is fixed, at its end adjacent to the manifold 10, to the plate 32 at by means of a collar 59. Thus, the resumption of the bending forces is performed by the sets 56 of vertebrae fixed to the tray and the T-fitting is not subject to significant constraints which would otherwise damage type seals "grayloc" or the fitting itself.

There is shown in Figures 13 to 15 a gantry 60 used when installing a base 6 or 8, as described below.

This gantry 60 has a rigid U-shaped frame, the uprights 61 are pivotally fixed on the frame 31, around of a geometric axis of rotation V parallel to the geometric axis Y. More precisely, each upright 61 is fixed at its end lower removably on the frame 31 by means of a mechanism locking device 62 comprising a rotary member 63 mounted for rotation on the upright 61 and connected by a universal joint transmission 64 to a mechanism 65. This mechanism 65 makes it possible to actuate a hook 66 engaging on the end 67 of an axis fixed to the frame 31, for retain the gantry 60 on the frame 31 while allowing its rotation.

The angular displacement of the frame is limited to the pedestal 8 by stops 61a arranged on one side of the Y axis and by cables 61 b connecting the cross member of the gantry 60 and the frame 31, these cables being attached to 61b near the free edge of the frame 31 on the same side as the stops 61 a . The cables 61 b are tensioned when the gantry is arranged substantially perpendicular to the plane of the frame 31. The cables 61 b make it possible to maintain the gantry substantially perpendicular to the base even in the case where the center of gravity of the latter is not in the vertical half-plane delimited above by the geometric axis of rotation of the gantry. The base 6 has two supports 33 which box connection control umbilicals is better balanced than the base 8 and the angular displacement of the frame is limited by stops 61a disposed on either side of the axis Y.

The mechanism 65 comprises a nut 68 engaged on a rod threaded 69 rotated by the transmission 64. The nut 68 is articulated, around an axis parallel to the V axis, at one end 70 a link connected to the hook 66, itself articulated in 69 around an axis of rotation parallel to the axis V. The rotation of the member 63 causes through the transmission 64 the rotation of the threaded rod 69 and the rise of the nut 68, which leads to pivoting down hook 66 around the hinge pin 69. The pivoting of the hook 66 allows the end 67 to be released as illustrated in Figure 16. There is a dotted line on this figure the position of the hook 66 at the end of pivoting after the reassembly of the nut 68. Conversely, the gantry 60 can allow the recovery of a base placed on the seabed.

We will now describe with reference to FIGS. 17 to 21, how to install the installation 1 previously described.

We start by rolling out a first section of pipe flexible, for example section 9. When you come close to at the end of this section, we resume the tension due to the weight of the part immersed in the flexible pipe by means of a sleeve tightened on the flexible pipe and also called "chinese finger" or "sock", attached to a cable 72 wound on a winch.

The base 8 can then be brought to the rear of the laying vessel, on a tilting ramp 73. The respective end portions 21 and 20 of the flexible pipe sections 9 and 7 are fixed to the manifold 10 'mounted on the base 8. The gantry 60 rests on the rear stops 61 a . The frame 31 of the base 8 is fixed at the rear to a first cable 74 wound on a winch and the gantry 60 is fixed by its cross member to two slings connected to a second cable 75 also wound on a winch.

Before tilting the ramp 73, make sure there is a slack in the flexible pipe portion 9 located above the sock 71.

We then tilt the ramp 73 as illustrated in the figure 18. The sock 71 sui supports the pipe 9 makes it possible to avoid the appearance of bending movements which would be susceptible otherwise damage the connection between line 9 and the 10 'manifold.

The end portion 20 of flexible pipe is maintained by means of a gutter 76 suspended by a crane to minimize the bending moments exerted on the ends of the pipes The ramp 73 is fitted at the top with a deflection pulley 77 over which the cable 74 passes, which supports the base 8 when this the latter gradually descended into the water in position substantially vertical. Cable 74 takes almost all of the weight of the base 8 when it is launched.

The base 8 is then lowered into the water and when it reaches a depth of a few tens of meters, we proceed to detaching the sock 71 using a manipulator robot (R.O.V) as illustrated in figure 19. The cable 75 connected to the gantry 60 is not tense. The weight of the base 8 and the pipe section hose located under the latter are taken up by cable 74.

Then proceed to the gradual tilting of the base 8 to bring it into a horizontal position. For that, we decrease gradually the tension of cable 74 by increasing that of cable 75 and when the latter is stretched, the cable 74 is detached by means of a robot manipulator. We are then in the configuration of the Figure 20, the base 8 being located about ten meters high compared to the bottom. This figure is represented by hatching the location on which the base 8 must be placed.

After the installation of the base 8 on the seabed, we give slack in the cable 75 before detaching the gantry 60 from the frame 31 of the base 8 as shown in FIG. 21.

To detach the gantry 60, we rotate the organs rotary 63 by means of a manipulator robot so as to release the hooks 66 of the ends 67. Thanks to the distance separating the rotary organs 63 of the seabed, the rotary organs 63 are when activated at a height from the seabed sufficient for any particle clouds raised by the propellers of the manipulator robot do not obstruct the visibility of this latest.

After detachment from gantry 60, the latter is recovered and placed on the base 6 which is placed in a similar manner.

To carry out the laying of sections 5, 7 and 9 and bases 6 and 8, the laying vessel has described a loop without having to reverse. It is not outside the scope of the invention to proceeding in the opposite direction, that is to say by first laying the section 5.

To install the connection boxes for the umbilicals, bring the connection box at the end of a cable above the corresponding support and engage in the guide 33 b of the latter a chain extending the lower pin associated centering, as illustrated in figure 22.

After installing the connection boxes, we carry out using a manipulator robot, the operations of connecting the umbilicals between them.

Before connecting the flange 11 with the associated pipe 12, the orientation of the axis is corrected if necessary H of the flange 11 by turning with a robot manipulator the knobs 45 and 50. We observe thanks to a camera placed on the robot manipulator, the spirit level 51 which provides information on horizontality of plate 32.

It will be noted on examining FIG. 2 in particular that the flange 11 is located at the bottom of a guide structure comprising two panels 11 a , 11 b used to position the connector fitted to the pipe 12 before it descends on the flange 11. A guide 11 c allows the passage of a cable used to flatten said connection if necessary against the panels 11 a and 11 b before its descent on the flange 11. It will be noted in FIG. 5 that the panels 11 a and 11 b are connected by an arch 11 d which does not obstruct the access of the robot manipulator to the flange 11, to the wheels 45 and 50 and allows the robot manipulator to see the spirit level 51.

Of course, the invention is not limited to the example of realization which has just been described.

One could in particular, in an alternative embodiment not shown, mount the plate 32 on three feet arranged as the vertices of a triangle on the frame 31, and the height of which would be adjustable, so that the tray can be positioned with a orientation chosen in relation to the frame.

We could still, in another variant not shown, attach the manifold to the frame for connecting the flexible pipes and the pipe coming from the wellhead, by simply mounting the flange for connecting the pipe from the submarine well on an adjustable joint of the joint type spherical, which would be positioned with the desired orientation using of a robot manipulator before making the connection.

Claims (16)

1. Manifold support mounting plate (6; 8) for an oil extracting installation, this mounting plate being intended for resting on the ocean bed and supporting a manifold (10; 10') for making a sealed connection between a pipe (12) coming from an underwater structure (2; 3) such as an underwater wellhead, and at least one terminal part (17; 18; 20; 21) of at least one flexible pipe section (5, 7, 9), the manifold (10; 10') comprising, furthermore, a flange (11) for connection to the said pipe (12) coming from the said underwater structure (2; 3), characterized in that the mounting plate comprises means for orienting the axis (H) of the said connecting flange (11) in a selected direction, before the connection of the said flange to the said pipe (12) is made.
2. Manifold support mounting plate according to Claim 1, the said pipe (12) being equipped with a union comprising a locking member capable of coming into a locking position as a result of the effect of gravity, characterized in that the said selected direction corresponds to the vertical, with an angular tolerance less than or equal to 10°, preferably less than or equal to 5°.
3. Manifold support mounting plate according to one of Claims 1 or 2, characterized in that it comprises a fixed frame (31), intended for resting on the ocean bed, and a platform (32) which is orientable relative to the frame and to which the said manifold (10; 10') is fixed.
4. Manifold support mounting plate according to Claim 3, characterized in that the said platform (32) is connected to the said frame (31) by means of a cardan-type joint.
5. Manifold support mounting plate according to any one of Claims 1 to 4, characterized in that it comprises means for positioning the said connecting flange (11) and for maintaining the latter in the selected position.
6. Manifold support mounting plate according to any one of Claims 1 to 5, characterized in that it comprises means (67) for the removable fixing of a gantry (60) used for installing and/or recovering the mounting plate placed on the ocean bed.
7. Offshore oil extracting installation (1) comprising two mounting plates (6, 8), of which at least one is a mounting plate as defined in any one of Claims 1 to 6, each mounting plate resting on the ocean bed and supporting a manifold (10; 10') connected at two ends to two respective terminal joining pieces of flexible pipe sections (5, 7; 7, 9) fixed to the manifold (10; 10') substantially in the extension of one another, each manifold (10; 10') comprising, furthermore, a flange (11) for sealed connection to a pipe (12) coming from an underwater structure, such as a wellhead (2; 3), the manifolds (10; 10') of the two mounting plates (6; 8) being connected to one another at one end by means of a flexible pipe section (7) and being connected at the other end to a surface extracting installation (4) by means of respective flexible pipe sections (5, 9).
8. Installation according to Claim 7, characterized in that those portions of the flexible pipes which are near the joining pieces fixed to the manifold can each slide in a curvature limiting member (56) integral with the said mounting plate (6; 8).
9. Installation according to Claim 8, characterized in that the said curvature limiting member (56) consists of an assembly (56) of vertebrae (57, 58) which is fixed at one end to the said mounting plate (6, 8) and inside which the said pipe portion near the joining piece fixed to the manifold can slide.
10. Installation according to any one of Claims 7 to 9, characterized in that the said manifolds are each generally T-shaped, the said flange (11) for connection to the pipe (12) coming from the associated underwater structure being carried by the central branch of the T.
11. Installation according to any one of Claims 7 to 10, characterized in that one (8) of the two mounting plates supports a valve (14) making it possible to put in communication or isolate the manifolds (10, 10') located on the two mounting plates (6, 8).
12. Installation according to any one of Claims 7 to 11, comprising a network of lines for the remote control of underwater members, such as valves, which network consists of pipes of the umbilical type, characterized in that this network comprises a first umbilical connecting the surface extracting installation and a first mounting plate (6) and a second umbilical connecting the first mounting plate to the second mounting plate (8).
13. Method for installing an oil installation, this installation comprising two mounting plates (6, 8) intended for resting on the ocean bed, of which at least one is a mounting plate as defined in any one of Claims 1 to 6, each mounting plate (6, 8) supporting -a manifold (10; 10')- intended to be connected at two ends to two respective flexible pipe sections (5, 7; 7, 9) fixed to the manifold (10; 10') substantially in the extension of one another, each manifold comprising, furthermore, a flange (11) for sealed connection to a pipe (12) coming from an underwater structure (2; 3), such as a wellhead, the said manifolds being intended to be connected to one another at one end by means of a flexible pipe section (7) and at the other end to a surface extracting installation (4) by means of respective flexible pipe sections (5, 9), this installation method comprising the steps involving in succession:

    unwinding a first flexible pipe section (9) onto the bed by means of an installation ship,

    putting into the water a first mounting plate (8), previously connected to the first section and to a second section, whilst at the same time unwinding the start of the second section and the end of the first,

    unwinding the said second flexible pipe section (7) onto the bed,

    putting into the water the second mounting plate (16), previously connected to the second section and to a third flexible pipe section, whilst at the same time unwinding the start of the third section and the end of the second,

    unwinding the said third flexible pipe section onto the bed, the installation ship substantially executing a loop in order to install the three pipe sections (9, 7, 5).
14. Method according to Claim 13, characterized in that each mounting plate (6, 8) is put into the water when the mounting plate is connected to the installation ship by means of two cables (74, 75), a first cable (74) being attached to the rear of the mounting plate and a second cable (75) being attached to a rigid gantry (60) articulated on the mounting plate, only the cable (74) connected to the rear of the mounting plate serving ror supporting the mounting plate in a first stage of the descent, the tension in this cable being relaxed when the mounting plate reaches a particular depth, the cable (75) attached to the gantry (60) then serving for bringing the mounting plate into a substantially horizontal position and subsequently for retaining it until it is installed on the ocean bed.
15. Method according to Claim 14, characterized in that the gantry (60) is fixed removably to the mounting plate so as to be capable of being recovered after the installation of the mounting plate and of serving for installing the next mounting plate.
16. Method according to Claim 15, characterized in that the gantry (60) comprises at least one rotary actuation member (63) intended to be actuated by a handling robot, this rotary actuation member being connected by means of a transmission (64) to a mechanism capable of converting the rotation of the said member (63) into a movement for unlocking a hook (66) fixing the gantry (60) to the mounting plate.

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