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. The construction of the system allows free vertical expansion of the risers along the entire structure. In addition, in the construction method developed for this system, the required area is significantly reduced.

Claims

1. A connection system between composite material risers and flowlines forming a lower riser termination assembly (LRTA) (15), applicable to the hybrid riser system (1) made of composite material and comprised by a vertical section, named bundle (3), pulled by a float (4) at an upper end (6) of the bundle (3), wherein a connection between 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 composite risers (9), as well as a connection between flexible jumpers (7) and the bundle (3) of the 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 the composite risers (9) and by guides (10) for the composite risers (9), having, at a lower end of the bundle (3), 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 the 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 a proper connection position with the flowlines (13), wherein the directing guides (10B) of the composite risers (9) are comprised of internal parts (22) and outer parts (23), made of polymeric material, wherein internal parts (22) and outer parts (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).

2. The LRTA connection system (15), according to claim 1, characterized in that the tubular steel members are tubular pass-through members (20) and tubular closing members (20A), which comprise the bending limiting structure (11) forming the compartments (21); the tubular pass-through members (20) defining longitudinal spaces for the composite risers (9) to pass through and the tubular closing members (20A) establishing the bending limit curvature of the composite risers (9); the tubular closure members (20A) being connected to the pass-through pipe members (20) only after the composite risers (9) have passed through.

3. The LRTA connection system (15) according to claim 2, characterized in that the tubular closure members (20A) form a bend with a radius greater than a minimum bending radius ranging from 4 to 20 m; and an arch length of the bending limiting structure (11), which limits the bending of the composite risers (9), should correspond to an angle from 15 to 45 degrees.

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

5. A hybrid riser system (1) construction method with the connection system (15) as defined in claim 1, characterized by the following steps: a. arranging two 12 m pipes at a welding station (27) for the formation of a first section of the rigid pipeline core (8); b. arranging the first section of the rigid pipeline core (8), after welding of the first section of the rigid pipeline core (8), at a welding inspection station (28) and, after the welding is inspected, arranging the welded section in a welding repair station (29) for any repairs; c. arranging the first rigid pipeline core section (8) at a welding joint lining station (30) to line the welding; d. connecting an end of a tensioner (31) to a tugboat (41), which after welding (27), inspection (28), possible repairs (29) and joint lining (30), contains the first section of the rigid pipe core (8); e. displacing the first rigid pipeline core section (8) towards an offshore launch ramp (38) with the aid of the tugboat (41) until there is room for a next 12 m pipe making part of the rigid pipeline core (8), to be inserted into the welding station (27); f. receiving, in the structure of the rigid pipeline core section (8) under construction moved to a position just in front of the tensioner (31), internal parts (22) of riser guides (10B), assembled in a riser guide internal parts assembly station (33); g. arranging, simultaneously to the step “f”, the next pipe, which was inserted in the process to make up the rigid pipeline core (8) in the welding station (27), and repeating steps “b” “c”, “d”, “e” and “f”, and so on and on; h. stopping the rigid pipeline core (8) construction, by the time the rigid pipeline core length (8) under construction reaches the offshore launch ramp (38), for assembly of the LRTA connection system (15), the system (15) being prefabricated, consisting of the internal parts (22) of the guides (10B) and a bending limiting structure (11) without tubular closing members (20A); the 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. restarting the construction of the rigid pipeline core (8) by inserting an additional 12 m of pipe into the welding station (27) and repeating steps “b”, “c”, “d”, “e” and “f”, once the LRTA connection system (15) is assembled; j. connecting, in parallel to step “i” and complying with design assumptions, the composite risers (9) stored in coils (35) 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. assembling the tubular closing members (20A) of the bending limiting structure (11) next to pass-through tubular members (20) and to outer parts (23) of the guides (10) and (10B); l. continuing to position the composite risers (9) along the structure as the rigid pipeline core (8) is assembled and the internal parts (22) of the riser guides are installed, at the riser guide internal parts assembly station (33), and subsequently installing the outer part of the riser guides (23) at a riser guide outer parts assembly station (37); and, m. transporting the bundle (3), now complete, by the offshore launch ramp (38) until the bundle (3) reaches full buoyancy.

6. A connection system between composite material risers and flowlines forming a lower riser termination assembly (LRTA) (15), applicable to the hybrid riser system (1) made of composite material and comprised by a vertical section, named bundle (3), pulled by a float (4) at an upper end (6) of the bundle (3), wherein a connection between 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 composite risers (9), as well as a connection between flexible jumpers (7) and the bundle (3) of the 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 the composite risers (9) and by guides (10) for the composite risers (9), having, at a lower end of the bundle (3), 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 the 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 a proper connection position with the flowlines (13), wherein the tubular steel members are tubular pass-through members (20) and tubular closing members (20A), which comprise the bending limiting structure (11) forming the compartments (21); the tubular pass-through members (20) defining longitudinal spaces for the composite risers (9) to pass through and the tubular closing members (20A) establishing the bending limit curvature of the composite risers (9); the tubular closure members (20A) being connected to the pass-through pipe members (20) only after the composite risers (9) have passed through.

7. The LRTA connection system (15) according to claim 6, characterized by the fact in that the tubular closure members (20A) form a bend with a radius of which should be greater than a minimum bending radius informed by the riser (9) pipe manufacturer ranging from 4 to 20 m; and an arch length of the bending limiting structure (11), which limits the bending of the riser (9), bending should correspond to an angle from 15 to 45 degrees.

8. A connection system between composite material risers and flowlines forming a lower riser termination assembly (LRTA) (15), applicable to the hybrid riser system (1) made of composite material and comprised by a vertical section, named bundle (3), pulled by a float (4) at an upper end (6) of the bundle (3), wherein a connection between 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 composite risers (9), as well as a connection between flexible jumpers (7) and the bundle (3) of the 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 the composite risers (9) and by guides (10) for the composite risers (9), having, at a lower end of the bundle (3), 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 the 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 a proper connection position with the flowlines (13), wherein the direct connection connectors (12) have an alignment system between a connector part located on the composite risers (9) and a connector part located on a flowline (13), which allows an alignment at any position of a connecting axis, the alignment system being incorporated into the connector (12) parts and/or a recoverable tool.

Description

DESCRIPTION OF FIGURES

(1) FIG. 01—Hybrid Composite Riser general arrangement

(2) FIG. 02A—First extreme hybrid riser position

(3) FIG. 02B—Second extreme hybrid riser position

(4) FIG. 03—Connection system between risers and flowlines—state of the art

(5) FIG. 04—Connection system between risers and flowlines—developed system

(6) FIG. 05A—Side view of the bending limiting structure

(7) FIG. 05B—Upper view of the bending limiting structure

(8) FIG. 06A—Side view of the guide for directing composite risers

(9) FIG. 06B—Front view of the guide for directing composite risers

(10) FIG. 06C—Detailed view of the guide for directing composite risers

(11) FIG. 07—Building site layout

DETAILED INVENTION DESCRIPTION

(12) 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).

(13) 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) with a float risers (11), connected to the rigid (50) anchored to the seabed 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

(14) 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.

(15) 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 system (1).

(16) 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.

(17) 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 parts of the connector (12) or into a recoverable tool, or also into both.

(18) The Hybrid Riser system (1) design 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) of the Hybrid Riser system (1) considering movement of the UEP (2) and the current, as represented in FIGS. 02A and 02B.

(19) FIGS. 05A and 05B show 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.

(20) FIGS. 06A, 06B and 06C show 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 outer 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.

(21) 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), a riser guide internal parts assembly station (33), a positioning area (34) for the riser (9) coils (35), a storage area for the riser guide outer parts (36), a riser guide outer parts assembly station (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).

(22) The Hybrid Riser system (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 internal parts 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).

(23) 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 riser guide internal parts assembly station 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 outer 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.

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