SYSTEM FOR CONNECTING BETWEEN RISERS OF COMPOSITE MATERIAL AND FLOWLINES, WHICH CAN BE USED WITH A HYBRID RISER, AND METHOD FOR CONSTRUCTING SAME

Abstract

This invention relates to oil and gas exploration and comprises a direct connection system referred to as a Lower Riser Termination Assembly (LRTA), between risers made of composite material and horizontal lines installed on the seabed (flowlines). The system is applicable to a hybrid riser and its construction method allows cost reduction and system assembly/installation time optimization. The LRTA connection system is applicable to both rigid and flexible flowlines without need for any intermediate connection section/equipment between these and the risers.

Another important feature of the presented system is the fact that its construction allows free vertical expansion of the risers along the entire structure.

In addition, while, in the state of the art, the conventional methods require a large assembly and construction area, in the construction method developed for this system, the required area is significantly reduced, approximately 10 times smaller than that required for known construction methods.

Claims

1. A connection system between composite material risers and flowlines forming an LRTA (15), applicable to the hybrid riser (1) made of composite material and comprised by a vertical section, named bundle (3), pulled by a float (4) at its upper end (6), where the connection of the float (4) to the upper end (6) of the bundle (3) is made by a tether (5) and the upper end (6) is provided with an anchoring point for the composite risers (9), as well as a connection between the flexible jumpers (7) and the bundle (3) of composite risers (9), where the flexible jumpers (7) are connected to a stationary production unit (UEP) (2); the bundle (3) being comprised of a rigid pipeline core (8), by composite risers (9) and by guides (10) for the composite risers (9), having, at its lower end, the LRTA (15) characterized by being comprised of guides (10B) connected to the rigid pipeline core (8), by a bending limiting structure (11) of the composite risers (9), also connected to the rigid core pipeline (8), and by direct connection connectors (12) between composite risers (9) and flowlines (13), where the limiting bending structure (11) is manufactured from tubular steel members (20) and (20A), forming compartments (21) through which the composite risers (9) pass for the proper connection position with the flowlines (13).

2. The LRTA connection system (15), in accordance with claim 1, characterized by the directing guides (10B) of the composite risers (9) being comprised of internal parts (22) and external parts (23), made of polymeric material, where parts (22) and (23), once joined, have a cylindrical shape being connected to the rigid core (8) by means of a compression tape (24) manufactured in Kevlar, directing the composite risers (9) to the compartments (21) of the bending limiting structure (11).

3. The LRTA connection system (15), according to claim 1, characterized by the fact that the tubular pass-through members (20) and tubular closing members (20A) comprise the bending limiting structure (11) forming the compartments (21); the tubular pass-through members (20) defining longitudinal spaces for the passage of composite risers (9) and the tubular closing members (20A) establishing the bending limit curvature of such risers (9); the tubular closure members (20A) being connected to the pass-through pipe members (20) only after the passing of the composite risers (9).

4. The LRTA connection system (15) according to claim 3, characterized by the fact that the tubular closure members (20A) form a bend the radius of which should be greater than the minimum bending radius informed by the riser (9) pipe manufacturer ranging from 4 to 20 m; and the arch length of the bending limiting structure (11) which limits the riser (9) bending should correspond to an angle from 15 to 45 degrees.

5. The LRTA connection system (15) according to claim 1, characterized by the fact that the direct connection connectors (12) have an alignment system between the connector part located on the composite riser (9) and the connector part located on the flowline (13), which allows an alignment at any position of the connecting axis, such system being incorporated into the connector (12) parts and/or a recoverable tool.

6. A hybrid riser (1) construction method with the connection system (15) according to claim 1, characterized by the following steps: a. Arrangement of two 12 m pipes at the welding station (27) for the formation of the first section of the rigid pipeline core (8); b. After the welding the first section of the rigid pipeline core (8), it is arranged at the welding inspection station (28) and, after the weld is inspected, the welded section is arranged in the weld repair station (29) for any repairs; c. Arrangement of the first rigid pipeline core section (8) at the welding joint lining station (30) to line the weld; d. After the welding (27), inspection (28), possible repairs (29) and joint lining (30), the first section of the rigid pipe core (8) is contained by the tensioner (31) and its end is connected to the tug boat (41); e. Displacement of the first rigid pipeline core section (8) towards the offshore launch ramp (38) with the aid of a tugboat (41) until there is room for the next 12 m pipe making part of the rigid pipeline core (8), to be inserted into the welding station (27); f. The rigid pipeline core section (8) under construction moved to the position just in front of the tensioner (31) receives, in its structure, the internal parts of the riser guides (22), assembled in the assembly station of the riser guides (33); g. Simultaneously to the step “f”, the new pipe that was inserted in the process to make up the rigid pipeline core (8) is arranged in the welding station (27), and steps “b” “c”, “d”, “e” and “f”, are repeated, and so on and on; h. When the rigid pipeline core length (8) under construction reaches the offshore launch ramp (38), the core (8) construction is stopped for assembly of the LRTA connection system (15), such system being prefabricated, consisting of the internal parts (22) of the guides' (10B) and the limiting bending structure (11) (without the tubular closure members (20A)); such LRTA system (15) being positioned on the offshore launching ramp (38) by a crane (40) to then be connected to the rigid pipeline core (8) by welding; i. Once the LRTA connection system (15) is assembled the construction of the rigid pipeline core (8) is restarted by inserting an additional 12 m of pipe into the welding station (27) and the repetition of steps “b”, “c”, “d”, “e” and “f”; j. In parallel to step “i” and complying with the design assumptions, the composite risers (9), stored in coils (35) are connected to the structure under construction, passing through the internal parts (22) of the guides (10) and (10B) and compartments (21) of the bending limiting structure (11), in order to be properly positioned for connection to the flowlines (13); k. Next, the tubular closing members (20A) of the bending limiting structure (11) are assembled next to the pass-through tubular members (20) and the outer parts (23) of the guides (10) and (10B); l. As the rigid pipeline core (8) is assembled and the internal parts (22) of the riser guides are installed (assembly station for the guides internal parts (33)), the composite material risers (9) continue to be positioned along the structure, with subsequent installation of the outer part of the riser guides (23) (assembly station of the outer guide parts (37)); and m. The bundle (3), now complete, is transported by the offshore launch ramp (38) until it reaches full buoyancy.

7. The LRTA connection system (15), according to claim 2, characterized by the fact that the tubular pass-through members (20) and tubular closing members (20A) comprise the bending limiting structure (11) forming the compartments (21); the tubular pass-through members (20) defining longitudinal spaces for the passage of composite risers (9) and the tubular closing members (20A) establishing the bending limit curvature of such risers (9); the tubular closure members (20A) being connected to the pass-through pipe members (20) only after the passing of the composite risers (9).

Description

DESCRIPTION OF FIGURES

[0048] FIG. 01—Hybrid Composite Riser general arrangement

[0049] FIG. 02—Extreme Hybrid Riser Positions

[0050] FIG. 03—Connection system between risers and flowlines—state of the art

[0051] FIG. 04—Connection system between risers and flowlines—developed system

[0052] FIG. 05—Bending limiting structure

[0053] FIG. 06—Guides for directing risers made of composite material

[0054] FIG. 07—Building site layout

DETAILED INVENTION DESCRIPTION

[0055] For a better understanding of the advantages of this invention in relation to the state of the art, a comparison between the components necessary for the state-of-the-art systems is presented below (FIG. 03) and the components required for the system shown herein (FIG. 04).

TABLE-US-00001 TABLE 1 Comparison between state-of-the-art systems and the developed system State of the art (FIG. 03) Developed System (FIG. 04) Rigid pipeline core (8A) Rigid pipeline core (8) Rigid Risers (9A) Risers made of composite material (9) Riser (9A) guides (10A) Riser (9) guides (10) (connected to (connected to the rigid the rigid pipeline core (8)) pipeline core (8A)) Guides for vertical rigid Bending limiting structure of the riser expansion (17) risers (11), connected to the rigid pipeline core (8) Rigid flowlines (13A) Rigid flowlines **(13) Intermediate connection Guides (10B) and Direct connection section/equipment (18) connectors (12) between risers (9) between risers (9A) and flowlines (13) and flowlines (13A): Flexible Jumpers or rigid spools Vertical connectors (12A) between risers (9A) and intermediate connection piece/equipment (18) Submarine pipeline termination equipment (PLET) (19) Vertical connectors (12A) between intermediate connection section/ equipment (18) and PLET (19) **or flexibles

[0056] From table 1 we can clearly see the advantages of the proposed system, especially with regard to the significant decrease in the number of components required to operate the system.

[0057] FIG. 01 shows a Hybrid Riser system (1) made of composite material, consisting of a vertical section, named bundle (3), pulled by a float (4) at its upper end (6), the thrust of which provides stability to the system. The connection between the float (4) and the upper end (6) of the bundle (3) is made by a tether (5). The upper end (6) also, provides an anchoring point for the composite risers (9) as well as a connection between the flexible jumpers (7) and the composite risers (9) of the bundle (3). The flexible jumpers (7) are connected to the stationary production unit (UEP) (2), ensuring that only part of the dynamic load is transferred to the Hybrid Riser (1).

[0058] The bundle (3) is composed by: a rigid pipeline core (8)—structural component, manufactured with steel pipe with 18-30 inch nominal diameter, which transfers the sustaining force produced by the float (4) to the anchor (14); by composite risers (9) with 3-14 inch nominal diameter; and guides (10) for the risers (9). Due to the submerged weight of composite risers (9), the bundle (3) has no need for additional floats.

[0059] The LRTA Connection System (15) between composite risers (9) and flowlines (13), object of this invention is located at the lower end of the bundle (3). Such a system (15) is comprised of: guides (10B) that direct the composite risers (9) to the final connection position with the flowlines (13); bending limiting structure (11) for the risers (9); and direct connection connectors (12) between risers (9) and flowlines (13). The direct connection connectors (12) have an alignment system between the connector part located on the composite riser (9) and the connector part located on the flowline (13). This system allows an alignment at any position of the connecting axis, that is, it is an alignment system working independently of the position of the parts to be connected. Such a system can be incorporated into the connector parts (12) or into a recoverable tool, or also into both.

[0060] The Hybrid Riser design (1) should establish: the assembly position of the bending limiting structure (11) in relation to the seabed; its length; and the direct connection connector position (12) between the composite risers (9) and the flowline (13). Such parameters depend on the flowline resistance (13) and the extreme positions (16) and (16A) the Hybrid Riser (1) considering movement of the UEP (2) and the current, as represented in FIG. 02.

[0061] FIG. 05 shows the bending limiting structure (11) which can be manufactured, for example, from tubular steel members. The bending limiting structure (11) is comprised of tubular feed-through members (20) through which the risers (9), and tubular closing members (20A) pass, which establish the bending limit of the risers (9). The bending limiting structure (11) has compartments (21) that direct the composite risers (9) with the help of guides (10B), for the proper position of connection with the flowlines (13), thus avoiding interference. The tubular closing members (20A) form a bend to limit the bending of the composite risers (9), and are installed after the composite risers'(9) assembly. The radius of that bend should be greater than the minimum bending radius informed by the riser pipe manufacturer (9), which typically ranges from 4 to 20 m. The arch length of the bending limiting structure (11) limiting the riser (9) bending should correspond to an angle from 15 to 60 degrees.

[0062] FIG. 06 shows the composite risers (9) directing guides (10B) toward the compartments (21) of the bending limiting structure (11). The directing guides (10B), as well as all the other guides (10) of the bundle (3), are comprised of internal parts (22) and external parts (23) manufactured, for example, in polymeric material. All parts (22) and (23) are fastened to the rigid pipeline core (8) by means of a compression tape (24) manufactured of a resistant material, such as, for example, Kevlar.

[0063] FIG. 07 shows the building site (42) floor plan of the proposed system, being comprised of: a pipe storage area (25) for the rigid pipeline core assembly (8); a mobile crane (26), a welding station (27), a welding inspection station (28), a weld repair station (29), a welding joint lining station (30), a tensioner (31), a storage area for the riser guide internal parts (32), an assembly station for the riser guide internal parts (33), a positioning area (34) for the riser (9) coils (35), a storage area for the riser guide external parts (36), an assembly station for the riser guide external parts (37), an offshore launching ramp (38), a storage area (39) of the connection system between LRTA risers and flowlines (15), a crane (40) and a tug boat (41).

[0064] The Hybrid Riser (1) construction, provided with the LRTA connection system (15) shown herein, is initiated by the assembly of the rigid pipeline core (8), which is comprised by the welding of 12 m long standard pipes. Thus, after welding (station 27), inspection (station 28), possible repair (station 29) and weld joint lining (station 30) of the first rigid pipeline core (8) section, the section is contained by the tensioner (31) and its end is connected to the tug boat (41). The first rigid pipeline core (8) section is then pulled by the tug boat (41) towards the offshore launch ramp (38), making room for a next pipe to be welded to the core (8). The tug boat (41) pull is compensated by the tensioner (31) and thus, the rigid pipeline core (8) stands still, allowing the system to be built at the stations. At this moment, the section of the rigid pipe core (8) under construction just ahead of the tensioner (31) receives, in its structure, the internal parts of the riser guides (22), mounted in the riser guide assembly station (33). Then, the assembly of the rigid pipeline core continues (8) to the limit where its end reaches the offshore launch ramp (38). Then, the construction of the rigid pipeline core (8) is interrupted for the connection of the LRTA riser and flowline connection system (15). This system (15) is prefabricated, containing the guides (10B) internal parts (22) and the bending limiting structure (11), without the tubular closing members (20A), already assembled. The system (15) is positioned on the offshore launch ramp (38) by a crane (40) to then be connected to the rigid pipeline core (8).

[0065] Once the connection system between risers and flowlines (15) is connected to the rigid pipeline core (8), the composite risers (9), stored in coils (35), are connected to the structure (in the internal parts of the guides (33) passing through the compartments (21) and by the guides (10B) of the connection system (15), so that they are properly positioned for connection with the flowlines (13). Then, the tubular closing members (20A) of the bending limiting structure (11) and external parts (23) of the guides (10B) can be fastened using compression tapes (24). Once the connection is completed, the construction of the rigid pipeline core (8) is restarted.

[0066] Once the bundle construction is completed (3), it is transported along the offshore launching ramp (38) until it reaches full buoyancy.