The present invention relates to the field of underwater installations enabling hydrocarbons to be conveyed between a seabed and a surface.
One field of application envisaged is notably that of petroleum exploitation at great depths.
Such well-known underwater installations include a riser pipe that extends from the seabed as far as an intermediate area overlying the seabed and situated below the surface and a flexible pipe connected to extend the riser pipe and that extends catenary fashion from the intermediate area to the surface where it is connected to a surface installation. The riser pipe is kept substantially vertical by means of a float submerged in the intermediate area. This type of installation makes it possible to raise hydrocarbons from the seabed to the surface without being constrained by disturbances of the surface linked to swell, currents or winds.
The document WO2009/112 687 describes an underwater installation of this type. The underwater installation usually includes a frame enabling the end of the riser pipe and the float to be connected together, and the frame is equipped with a curved swan-neck pipe that extends the riser pipe. The pipe has a free end provided with a connecting end fitting. In a first installation phase, the frame and the float are installed to hold the riser pipe in vertical equilibrium. In a second installation phase the flexible pipe terminated by a connector is connected to the end fitting, from the surface, so as to establish the connection between the riser pipe and the flexible pipe. To this end, the connector is specifically equipped with a retractable flange and is installed at the end of the flexible pipe. It approaches the frame as the flexible pipe is paid out from the surface. As for the frame, it includes retaining members and the retractable flange is then engaged in the retaining members. More of the flexible pipe is paid out and the connector then tilts around the retaining means so that it abuts against a bearing member and faces the end fitting on the pipe. The connector is then driven toward the end fitting by retracting the flange to connect them together.
Difficulties arise in connecting the connector to the end fitting at greater depths of water. In fact, the riser pipes are longer and consequently heavier. The same goes for the flexible pipes and the forces to be exerted on the connector are consequently higher. Now the latter connectors are fragile and costly. Moreover, during the phase of moving the connector and the frame closer to each other, and given the masses involved, the slightest impacts can have an impact on the integrity of the connector, notably when the connector tilts and comes into contact with the bearing member.
Also, a problem that arises and that the present invention aims to solve is to provide an underwater connection assembly that makes it possible to preserve the integrity of the connector during connection.
To this end, and according to first subject matter, the present invention an underwater connection assembly for connecting, between a seabed and a surface, a riser pipe extending from said seabed toward said surface and a flexible pipe extending to said surface, said riser pipe having a connecting upper end and said flexible pipe having a connecting lower end, said connecting assembly comprising on the one hand a longitudinal frame including a foot fastened to said connecting upper end and a head intended to be connected to a float and on the other hand a connector and a curved pipe having two opposite ends so as to be able to connect said flexible pipe in catenary manner to said riser pipe. According to the invention, one of said opposite ends of said curved pipe is adapted to be fastened to said connecting lower end while said connector is mounted at the other of said opposite ends so as to be able to drive said connector toward said connecting upper end in a direction oriented from said head toward said foot, guiding said curved pipe through said frame.
Accordingly, one feature of the invention resides in the use of the curved pipe, fixed in position at the connecting lower end of the flexible pipe, and no longer at the end of the riser pipe, and placing the connector at the other end of the curved pipe. As a result, the curved pipe is suspended from a guide cable going to a laying ship and in a first phase the curved pipe from which the flexible pipe is itself suspended is moved toward the frame in a direction substantially perpendicular to the riser pipe. The curved pipe is then passed through the frame at the level of the head, while the connector extends coaxially facing the connecting upper end of the riser pipe. The cable is then substantially released and the curved pipe descends through the longitudinal frame while the connector is driven coaxially toward the connecting upper end of the riser pipe onto which it is finally engaged. Consequently, the routing of the connector, both in the phase of approaching the frame and in the connection phase as such, protects it from impacts and consequently from damage.
Moreover, and in accordance with one particularly advantageous feature of the invention, the frame comprises guide ramps extending in said direction oriented from said head toward said foot to guide said curved pipe. As a result, the curved pipe can come to bear against the guide ramps so that when the guide cable is released it is guided in translation by the guide ramps toward the foot of the frame while the connector is for its part guided toward the connecting upper end. Preferably, said other of said opposite ends of said curved pipe comprises diametrically opposite guide studs adapted to cooperate with said guide ramps. The opposite guide studs therefore come to bear against the guide ramps and they are driven to rub against the latter when the guide cable is released.
In accordance with one particularly advantageous embodiment of the invention, said guide ramps comprise two posterior uprights respectively adapted to receive said guide studs that bear on them. The two posterior uprights are mounted parallel to each other and parallel to the direction of the frame extending from the head toward the foot. Moreover, said guide ramps preferably further comprise two anterior uprights respectively facing said posterior uprights so as to be able to trap said guide studs. Each of the guide studs is therefore mounted to slide between an anterior upright and a posterior upright. As a result, the curved pipe is perfectly guided in translation through the longitudinal frame simply by releasing the guide cable.
Moreover, the guide studs include longitudinal bearing surfaces extending parallel to the axis of said connector. Said other of said opposite ends is therefore immobilized against pivoting and the connector and the connecting end of the riser pipe therefore remain coaxial as they approach each other.
Also, said frame further comprises a receiving carriage mounted to slide on said guide ramps to receive said other of said opposite ends of said curved pipe that bear on it. The guide studs are for example adapted to come to bear on the receiving carriage, notably when the connector is connected to the connecting upper end of the riser pipe. As a result, the frame can be equipped with a device for driving the receiving carriage from the foot toward the head so as to be able to disconnect the connector as described in more detail hereinafter.
Said two opposite ends of said curved pipe advantageously define two axial directions substantially inclined one relative to the other, for example at an angle between 10 and 20°. Said other of said opposite ends of the curved pipe therefore extends substantially vertically, in line with the riser pipe which is itself vertical, while said one of said opposite ends is inclined. The flexible pipe then comes to extend in catenary fashion from this inclined opposite end.
Additionally, said curved pipe advantageously comprises a connecting beam for connecting together said two opposite ends. As a result, the two opposite ends of the curved pipe are held perfectly in a fixed position relative to each other and the curved pipe is perfectly rigid. Said connecting beam preferably includes an arm extending cantilever fashion in line with said connecting beam opposite said other of said opposite ends relative to said one of said opposite ends. The arm then makes it possible to site the anchoring of the guide cable remotely relative to the axis of the connector and therefore to be able to maneuver the guide cable without reference to the float above the frame. In accordance with a variant embodiment, said arm includes a removable part. This removable part can then be removed after the connection is established between the flexible pipe and the riser pipe.
In accordance with other subject matter, the present invention proposes a method of underwater connection between a seabed and a surface of a riser pipe extending from said seabed toward said surface and a flexible pipe extending to said surface, said riser pipe including a connecting upper end and said flexible pipe including a connecting lower end, said connection method being of the type wherein there are procured on the one hand a longitudinal frame having a foot fastened to said connecting upper end and a head intended to be connected to a float and on the other hand a connector and a curved pipe having two opposite ends so as to be able to connect said flexible pipe in catenary manner to said riser pipe. According to the invention, one of said opposite ends of said curved pipe is fastened to said connecting lower end, while said connector is mounted at the other of said opposite ends, and said connector is driven toward said connecting upper end in a direction oriented from said head toward said foot, guiding said curved pipe through said frame.
Other features and advantages of the invention will emerge on reading the following description of one particular embodiment of the invention given by way of nonlimiting illustration with reference to the appended drawings, in which:
This
Moreover,
Refer now to
With regard to the lower end 30 of the flexible tubular pipe 26, it is connected to a first end 62 of the curved pipe 32, which extends in a substantially inverted U-shape as far as a second end 64. This second end 64 terminates in the connector 34. It will be noted that the latter includes a female end-fitting. The first end 62 and the second end 64 are connected together by means of a connecting beam 68 which is extended by a cantilever arm 70 opposite the second end 64 relative to the first end 62 of the curved pipe 32. In accordance with the embodiment shown in
With regard to the second end 64 of the curved pipe 32, it includes oblong lateral guide studs 76, 78 that extend in an axial direction A of the connector 34 and project from the second end 64. To be more precise, the two oblong lateral guide studs 76, 78 define a middle plane axially intersecting the connector 34. Moreover, the oblong lateral guide studs 76, 78 respectively include two parallel and substantially plane opposite bearing surfaces parallel to the axial direction A of the connector 34.
It will be noted that the axial direction X of the first end 62 of the curved pipe 32 is inclined relative to the axial direction A of the connector 34. As a result, the flexible pipe 26, which is equipped with a stiffener sleeve that extends from the lower end 30 beyond the cantilever arm 70, exerts a weighting force substantially on the axis of the cable 28, which makes it possible for the connecting beam 68 and the arm 70 that extends it to remain substantially horizontal. Moreover, thanks to the horizontal distance between the anchoring end 74 and the second end 64 of the curved pipe 32, the connector 34 can be carried transversely through the frame 36 by means of the cable 28 without the float 20 being able to impede this.
As shown in
Starting from this relative position of the curved pipe 32 and the frame 36, the cable 28 is progressively released so as to lower the arm 70 and the connecting beam 68 relative to the frame 36 and thus to allow the guide studs 76, 78 to engage behind the anterior uprights 60, 58, respectively, inside the aforementioned guide spaces 59. The thickness of the oblong guide studs 76, 78 is substantially equal to the distance between the posterior uprights 54, 56 and the anterior uprights 58, 60, respectively, ignoring the functional clearance. As a result, the oblong guide studs 76, 78 slide freely inside the guide spaces 59 as the cable 28 is released.
Thanks to their plane opposite bearing surfaces respectively guided by the posterior uprights 54, 56 and the anterior uprights 58, 60, the oblong guide studs 76, 78 make it possible to hold the connector on the axis of the connecting upper end 52 during the phase of moving the connector 34 and the connecting end fitting 53 toward each other until the connector caps the connecting end fitting 53. The connection is then made automatically in a manner known in itself, for example by means of conical connecting members and spring-loaded locking jaws. The rigid riser pipe 12 and the flexible pipe 26 are then connected continuously and in a sealed manner via the curved pipe 32.
The oblong guide studs 76, 78 then bear on the receiving carriage 61.
The other end of the flexible pipe 26, which cannot be seen in
Refer now to
It is therefore a question of disconnecting the rigid riser pipe 12 and the flexible pipe 26. To this end a traction device, to be more precise a hydraulic cylinder 80 here, is installed by means of an underwater robot that is not shown. This is mounted when extended between the spacer 57 and the receiving carriage 61. As soon as disconnection is required, the hydraulic cylinder 80 is therefore caused to retract, which makes it possible to drive in translation the receiving carriage 61 on which the oblong lateral guide studs 76, 78 bear. Because of this, the second end 64 of the curved pipe 32 is driven in translation toward the upper end 42 of the frame 36 and likewise the connector 34 is disconnected from the male end fitting 53 of the connecting upper end 52.
A plug, not shown, is then installed in the connector 34 by means of the underwater robot in order to prevent return flow of the hydrocarbon. Maintenance operations can therefore be carried out on the riser pipe 12.
Number | Date | Country | Kind |
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1350662 | Jan 2013 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2014/050139 | 1/24/2014 | WO | 00 |