ON-BOARD FABRICATION OF PIPE-IN-PIPE ASSEMBLIES

Abstract

A pipelay vessel having two pipe string manufacturing lines and a firing line, wherein the pipe string manufacturing lines are designed for simultaneously handling two different pipe outer diameters for use as an inner pipe and an outer pipe respectively. Further, the vessel has a pipe-in-pipe assembly workstation for assembling the inner pipe and the outer pipe in a pipe-in-pipe configuration. The vessel is designed with a lay-out which allows for producing offshore pipe-in-pipe strings from single joints, wherein available space is optimally used and pipe-in-pipe strings can be produced safely offshore.

Claims

1. A pipelay vessel, comprising two pipe string manufacturing lines and a firing line, wherein the pipe string manufacturing lines are designed for simultaneously handling two different pipe outer diameters for use as an inner pipe and an outer pipe respectively and wherein the vessel further comprises a pipe-in-pipe assembly workstation for assembling the inner pipe and the outer pipe in a pipe-in-pipe configuration.

2. The vessel according to claim 1, wherein the pipe string manufacturing lines comprises one or more workstations for the fabrication of multi-length strings from single joints.

3. The vessel according to claim 1, wherein the pipe-in-pipe assembly station is configured for the assembly of pipe-in-pipe lengths with a string length ranging between one and up to four standard joint lengths.

4. The vessel according to claim 1, the vessel further comprising storage space for single pipe joints.

5. The vessel according to claim 1, the vessel further comprising: a) a weather deck; b) a J-lay pipe deployment facility comprising a tower arranged above the weather deck, for deployment of pipe in J-lay mode, received from the firing line; c) pipe handling equipment for delivering the pipe or pipe-in-pipe strings from the firing line to the tower.

6. The vessel according to claim 5, the vessel further comprising a moonpool, passing through the weather deck, and wherein the J-lay tower is located above the moonpool.

7. The vessel according to claim 1, the vessel further comprising on-board storage for the fabricated pipe-in-pipe strings.

8. The vessel according to claim 1, the vessel being arranged with the pipe string manufacturing lines below the weather deck.

9. The vessel according to claim 5, the vessel further comprising an S-lay pipe deployment facility located below the weather deck, comprising the firing line.

10. The vessel according to claim 9, wherein the J-lay tower is arranged for performing operations through the moonpool simultaneously with operation of the S-lay pipe deployment facility to manufacture the pipeline.

11. The vessel according to claim 9, wherein the firing line extends along a centreline of the vessel and wherein the moonpool is located to one side of the firing line.

12. The vessel according to claim 9, wherein the moonpool is separated from the firing line by a cofferdam extending to the weather deck.

13. The vessel according to claim 5, wherein the firing line comprises one of the workstations.

14. The vessel according to claim 5, wherein the pipe-in-pipe assembly station is arranged to assemble inner and outer pipe strings on the firing line.

15. The vessel according to claim 5, wherein the pipe-in-pipe assembly station is arranged parallel and adjacent to the firing line, such that a distance between the firing line and the pipe-in-pipe assembly station is less than 5 meters.

16. The vessel according to claim 9, wherein the pipe handling equipment comprises an elevator arranged to elevate pipe-in-pipe strings between the firing line to the weather deck.

17. A method of laying a pipe-in-pipe pipeline from a pipe-laying vessel having two independent and separate pipe string manufacturing lines, a firing line and a J-lay tower, the method comprising deploying pipe from the vessel in J-lay mode by: a) introducing single pipe in a first workstation of each of the two pipe string manufacturing lines, whereby the first pipe string manufacturing line receives inner pipes and the second pipe string manufacturing line receives outer pipes, the inner pipes having a smaller outer diameter than the inner diameter of the outer pipes; b) fabricating double-joints in a first type workstation of each pipe string manufacturing line; c) introducing the double-joints into the firing line; d) joining the doubles to form quad- or triple-joint pipe strings on the firing line; e) assembling the inner pipe and the outer pipe strings in a pipe-in-pipe configuration; f) presenting the pipe-in-pipe configuration to the J-lay tower; and g) connecting the pipe-in-pipe configuration to the pipeline and lowering the pipeline into the sea.

18. The method according to claim 17, wherein step e) at least in part is performed on the firing line.

19. The method according to claim 17, wherein the J-lay tower is located adjacent to a moonpool and wherein the pipe-in-pipe pipeline is lowered through the moonpool.

20. The method according to claim 17, wherein the steps a) to e) are performed below a weather deck and wherein the J-lay tower is located above the weather deck, the step f) further comprising elevating the pipe-in-pipe configuration to the weather deck.

21. The method of claim 17, wherein the vessel comprises two pipe string manufacturing lines and a firing line, wherein the pipe string manufacturing lines are designed for simultaneously handling two different pipe outer diameters for use as an inner pipe and an outer pipe respectively, wherein the vessel further comprises a pipe-in-pipe assembly workstation for assembling the inner pipe and the outer pipe in a pipe-in-pipe configuration, wherein the vessel further comprises: a) a weather deck; b) a J-lay pipe deployment facility comprising a tower arranged above the weather deck, for deployment of pipe in J-lay mode, received from the firing line; c) pipe handling equipment for delivering the pipe or pipe-in-pipe strings from the firing line to the tower.

22. The method according to claim 17, the method further comprising subsequent or prior to deploying pipe in J-lay mode, abandoning and recovering the pipeline and performing S-lay deployment of pipe over a stern of the vessel, wherein the vessel comprises two pipe string manufacturing lines and a firing line, wherein the pipe string manufacturing lines are designed for simultaneously handling two different pipe outer diameters for use as an inner pipe and an outer pipe respectively, wherein the vessel further comprises a pipe-in-pipe assembly workstation for assembling the inner pipe and the outer pipe in a pipe-in-pipe configuration, wherein the vessel further comprises: a) a weather deck; b) a J-lay pipe deployment facility comprising a tower arranged above the weather deck, for deployment of pipe in J-lay mode, received from the firing line; c) pipe handling equipment for delivering the pipe or pipe-in-pipe strings from the firing line to the tower, and wherein the vessel further comprises an S-lay pipe deployment facility located below the weather deck, comprising the firing line.

23. A pipe-in-pipe assembly workstation for assembling inner and outer pipe strings in a pipe-in-pipe configuration, comprising multiple pipe line-up conveyor modules positioned for supporting an inner pipe string and an outer pipe string such that their centrelines form one continuous line, and a pipe push-pull system arranged to move the outer pipe string with respect to the inner pipe string.

24. The pipe-in-pipe assembly workstation according to claim 23, wherein one or more pipe line-up conveyor modules comprises a set of support rollers placed in a V-configuration, for supporting the outer pipe string and allowing a translational movement of the pipe along the centreline.

25. The pipe-in-pipe assembly workstation according to claim 22, wherein one or more pipe line-up conveyor modules comprises a set of motorized rollers, for transporting the outer pipe over the inner pipe to assemble the pipes to the pipe-in-pipe configuration.

26. The pipe-in-pipe assembly workstation according to claim 22, wherein one or more pipe line-up conveyor modules further comprises at least one spinning roller for supporting and rotating the inner pipe during insertion into the outer pipe.

27. The pipe-in-pipe assembly workstation according to claim 23, wherein the pipe push-pull system comprises a pipe end pusher, located at one end of the pipe-in-pipe assembly workstation, for pushing of the inner pipe string during pipe-in-pipe assembly.

28. The pipe-in-pipe assembly workstation according to claim 23, wherein the pipe push-pull system further comprises a double plug system for pulling an inner pipe string in both directions, comprising an inner pipe end cap, located on a first end of the workstation for connecting to a far end of the inner pipe string, and an outer pipe end cap, located at an opposite side of the workstation, for connecting to a far end of the outer pipe string.

29. The pipe-in-pipe assembly workstation according to claim 28, wherein the double plug system further comprises an inner interconnection cable, connectable to the inward facing sides of the inner pipe end cap and the outer pipe end cap, through the pipe strings.

30. The pipe-in-pipe assembly workstation according to claim 28, wherein the pipe push-pull system further comprises an inner pipe winch, located on the pipe pusher and connectable to the outward facing side of the inner pipe end cap.

31. The pipe-in-pipe assembly workstation according to claim 28, wherein the pipe push-pull system further comprises an outer pipe winch, located on the opposite end of the workstation from the pipe pusher, connectable to the outward facing side of the outer pipe end cap.

32. The pipe-in-pipe assembly workstation according to claim 31, wherein the height and the distance from the outer pipe winch of the pipe end pusher is adjustable.

33. The pipe-in-pipe assembly workstation according to claim 23, wherein the workstation is no longer than 110 m.

34. The pipe-in-pipe assembly workstation according to claim 23, wherein the pipe-in-pipe assembly station is repositionable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be discussed in more detail below, with reference to the attached drawings, in which illustrative embodiments thereof are shown. The drawings are intended exclusively for illustrative purposes and not as a restriction of the inventive concept. The scope of the invention is only limited by the definitions presented in the appended claims.

[0038] FIG. 1 depicts a pipelay vessel according to an embodiment of the invention.

[0039] FIG. 2 shows a perspective view of the vessel's pipeline manufacturing lay-out according to an embodiment.

[0040] FIG. 3 shows a perspective view of the firing line with the pipe-in-pipe assembly workstation and the S-lay pipeline deployment equipment.

[0041] FIG. 4 shows a perspective view of part of the starboard side manufacturing line.

[0042] FIG. 5 shows a perspective view of the ready rack area as seen from the vessel's bow.

[0043] FIG. 6 shows a perspective view of the pipe-in-pipe assembly tooling of the pipe-in-pipe assembly workstation.

[0044] FIG. 7 provides a more detailed perspective view of the pipe end pusher of the push-pull system in the assembly workstation.

[0045] FIG. 8 gives a more detailed view of a pipe line-up conveyor module.

[0046] FIG. 9 shows a schematic cross-section of the pipe strings during pipe-in-pipe assembly, with pipe end pusher, end caps and winches.

DESCRIPTION OF EMBODIMENTS

[0047] FIG. 1 depicts a pipelay vessel 100 according to an embodiment of the invention. The vessel 100 comprises a hull 1, accommodation 5, a crane 6, a J-lay-tower 10 and an S-lay stinger 20, whereby the hull 1 has a bow 2, a stern 3 and a weather deck 4. Furthermore, the figure shows a pipeline 50 and the seabed 7. Below the weather deck 4 are further decks including a pipeline manufacturing deck 15. The pipelay vessels hull 1 is defined by the bow 2 at the front, defining the normal sailing direction, the stern 3 at the backside and the weather deck 4 at the top side. Above the weather deck 4, the accommodation 5 and crane 6 are located, as well as the J-lay tower 10. In the configuration shown, the accommodation 5 is located at the bow side, the J-lay tower 10 amidships and the crane 6 at the stern side, such that the crane 6 has full reach over the weather deck 4 and to the J-lay tower 6 without obstructing the view from the accommodation 5. The J-lay tower 10 lowers an on-board manufactured pipeline 50 to the seabed 7 through a moonpool 8 in the hull. Alternatively, the J-lay tower may be located to one side of the weather 4 deck, to allow J-lay pipe-deployment along a side of the vessel. Additionally, the vessel has an S-lay stinger 20 connected to the stern 3 of the hull 1, enabling the vessel to also perform pipelay operations in S-lay mode.

[0048] FIG. 2 shows a perspective view of the lay out of the vessel's pipeline manufacturing deck 15 according to an embodiment. The pipeline manufacturing deck 15 comprises a starboard side manufacturing line 60 and a portside manufacturing line 80, a pipe-in-pipe assembly workstation 94 and the firing line 19 (partially shown), as well as pipe handling equipment including conveyors 11 and elevators 12. In the present configuration, the firing line 19 is positioned on the centerline C of the vessel, comprising the pipe-in-pipe assembly workstation, and having one manufacturing line arranged on each side. Thus pipes move from the aft of the vessel towards the bow 2, via the manufacturing lines 60, 80, where they are assembled to pipe-in-pipe configuration in the pipe-in-pipe assembly workstation 94 and travel to the aft of the vessel again, via the firing line 19.

[0049] The manufacturing deck 15 is set up for manufacturing pipe strings from single-joints up to a maximum length of four single-joints. In the configuration shown, both manufacturing lines 60, 80 are set up for producing double-joint strings from single-joints, whereby in the present example the starboard side manufacturing line 60 is set-up for manufacturing of the outer pipe strings 54 and the portside manufacturing line for manufacturing of the inner pipe strings 52 for the pipe-in-pipe pipeline. Each pipe string manufacturing line 60, 80 has an area 62, 82 set up for assembly of single joints into double-joints. The pipes and pipe strings are conveyed from work area to work area using conveyors 11 of the on-board pipe handling equipment. Following assembly, the inner and outer pipe double-joint assemblies are collected in the manufacturing lines respective pipe handling racks 84, 64.

[0050] Further assembly of the double-joint strings into a quad-joint string, or alternatively a triple-joint string, is performed at the centerline of the vessel, using the firing line equipment. This will be done for both the outer and the inner pipe strings. As shown in FIG. 2, the quad-joint inner string 52 is scheduled to be welded and inspected while the quad-joint outer string 54 is still under assembly, allowing for thermal insulation and other items such as centralizers to be added to the inner pipe string 52 while the outer pipe string 54 is being finalized. The assembly of the inner and outer pipe strings 52, 54 is performed in the off-center pipe-in-pipe insertion tooling of the pipe-in-pipe assembly workstation 94, for which the inner and outer pipe strings 52, 54 are transferred off the firing line into the tooling. The length of the workstation 94 is sufficient for aligning two quad-joint strings in the tooling. Following assembly, the pipe-in-pipe string is transferred back onto the firing line 19 for further handling.

[0051] The vessel according to the embodiment depicted in FIG. 2 further comprises a moonpool 8 for J-lay deployment. To allow pipe string manufacturing in parallel with J-lay pipeline deployment, the moonpool 8 is located on one side of the firing line 19. Consequently, one of the manufacturing lines 60 is routed around the moonpool 8.

[0052] Furthermore, the pipeline manufacturing lay-out shown in FIG. 2 is a vessel embedded workstation, thus located in the hull below the weather deck. To allow single- and double-joint movement between the weather deck and the pipeline manufacturing lines 60, 80, the pipe handling equipment comprises pipeline elevators 12, 14.

[0053] FIG. 3 shows a perspective view of the firing line with the pipe-in-pipe assembly workstation 94 according to an embodiment of the invention. The firing line 19 and assembly workstation 94 further comprise working areas 40, pipe handling equipment and S-lay stinger 20.

[0054] The pipe handling equipment displayed comprises longitudinal conveyors 11, transfer arms 13, elevators 16 and tensioners 18. In the configuration of this example, the pipe-in-pipe assembly workstation 94 is located on the firing line and working as pipe-in-pipe quad-joint feeding line to the S-lay stinger 20 for pipeline 50 deployment in S-lay mode. Pre-fabricated pipe-in-pipe strings are lowered from the weather deck, using the elevators 16 on the firing line to the ex-centered pipe-in-pipe insertion tooling of the pipe-in-pipe assembly workstation 94. The quad-joint pipe-in-pipe string 56 is transferred towards the bow using longitudinal conveyors 11 up to a predetermined location along the firing line 19. Then the pipe-in-pipe string 56 is transferred to the firing line 19 using transfer arms 13. The firing line comprises multiple working areas 40 with dedicated tooling along the length of the pipe. In these work areas, activities such as welding, coating and inspections take place for joining the pipe-in-pipe string 56 to the pipeline 50. The final station 42 for pipe string to pipeline joining in S-lay is located on the firing line 19, adjacent to the first tensioner 18. The tensioners 18 securely hold the end of the pipeline, ahead of the stinger 20 from which the pipeline is deployed from the vessel. It will however be understood that although S-lay operation is disclosed, the vessel will not normally lay pipe-in-pipe in S-lay mode, since such a pipeline is only usually required in deep water operations in J-lay mode.

[0055] The elevators 16 on the firing line can also be used for lifting the pipe-in-pipe strings to the weather deck, following the pipe-in-pipe string manufacturing described for FIG. 1, either for pipe storage prior to S-lay pipelay mode or for lifting into the J-lay tower for pipelay in J-lay mode.

[0056] FIG. 4 shows a perspective view of part of the starboard side manufacturing line 60, dedicated to the outer pipe double-joint assembly. The starboard side manufacturing line 60, which is set up similarly to the portside manufacturing line, comprises single-joint elevators 12, longitudinal conveyors 11 and a double-jointing workstation 62. The double-jointing workstation has an inside diameter welding station 31, outside diameter welding stations 32, beveling stations 33, a field joint coating station 35, NDE stations 39 and pipe ends preparation stations 37. Additionally, the manufacturing line 60 includes an area 68 where the pipe-in-pipe assembly workstation can be relocated to for producing double-joint pipe-in-pipe strings, if the manufacturing lay-out is adjusted to run continuously and in parallel with pipelay in S-lay mode taking place.

[0057] FIG. 5 shows a perspective view of the ready rack area as seen from the vessel's bow. The ready rack area comprises the ends of the starboard and portside manufacturing lines 60, 80 and the start of the firing line 19, located along the vessel's centerline C. The ready rack is a buffer area for the inner double-joint strings 89 and the outer double-joint strings 69 coming of the portside and starboard side manufacturing lines 80, 60 and where they are selected for assembly into triple- or quad-joint strings. All pipe handling and process equipment in the ready rack area is suitable for and arranged such that it can work on both the inner pipe and outer pipe diameters. Additionally, the ready rack area comprises two internal line-up clamp systems 74, 75 for handling outer pipe and inner pipe internal line-up clamps 72, 73 as well as a messenger line system 71. The messenger line system is used to pre-install the wire required to connect the inner and outer pipe end caps during the pipe-in-pipe assembly. One wire is pre-installed in each inner and outer double joint on the ready rack.

[0058] FIG. 6 shows a perspective view of the pipe-in-pipe assembly tooling 200 of the pipe-in-pipe assembly workstation 94. The pipe-in-pipe assembly tooling is a push-pull system 200 comprising a pipe end pusher 240 and conveyor modules 210, 220. The conveyor modules 210, 220 and pipe end pusher 240 are placed such that two pipe strings 52, 54 placed into the push-pull system 200 are aligned. The pipe end pusher 240 is positioned to the inner pipe string 52 end. A number of conveyor modules 210, 220 are distributed along the full length of the assembly workstation, whereby a first set of conveyor modules 210 are set at a fixed elevation for supporting the outer pipe string 54 during the assembly and a second set of conveyor modules 220 drives the movement of pipes. The conveyor modules 220 of the second set are described in more detail in relation to FIG. 8, while details of the pipe end pusher 240 are provided with the description of FIG. 7. The workings of the push-pull system 200 are further detailed in relation to FIG. 9 below. The push-pull system is mounted on a bolted foundation with hydraulic and electrical quick coupling connections. This foundation allows easy relocation of the system from the quad-joint assembly location on the firing line to the double-joint buffer location in the ready rack area or to the bow end of the double-joint prefabrication workstation 68, depending on pipelay project requirements. The workstation may also be used in onshore pipe-in-pipe manufacturing facilities.

[0059] FIG. 7 provides a more detailed perspective view of the pipe end pusher 240 of the push-pull system 200 in the assembly workstation. The pipe end pusher 240 has a frame 241 with a bolted foundation 246, a longitudinal adjustment system 244, an inner pipe winch 242 and an inner pipe end cap 250. The inner pipe end cap is located at a top-side of the pipe end pusher frame 241.

[0060] The pusher frame is height adjustable, such that the height of the inner pipe end cap can be adjusted for various pipe diameters and offset requirements. The inner pipe winch 242 is located on the frame 241 at the opposite side from the end cap, such that the winch wire can be connected to the winch side of the end cap. The winch is used for tensioning the inner pipe string 52 prior to and during assembly operations, ensuring the inner pipe remains aligned and fully controlled during the operations. The pipe-in-pipe assembly with the pipe end pusher 240, including the tensioning operation, is further explained in relation to FIG. 9. The longitudinal adjustment system 244 is located at the base of the frame 241, directly above the bolted foundation 246, and is used for adjusting the pipe end pusher location in the length direction of the pipe strings 52, 54. The longitudinal adjustment system 244 enables the pipe end pusher 240 to be longitudinally adjusted over a distance of around 5 meters to compensate for the difference between the longest and shortest inner pipe-in-pipe strings 52.

[0061] FIG. 8 gives a more detailed view of a motorized pipe line-up conveyor module 220. The module 220 has motorized rollers 222, 224 and a frame 228 with a bolted foundation 226. A set of motorized rollers 222 are set in a V-shape for supporting the outer pipe string 54. Another set of motorized rollers 224 is located with its rotational axis parallel to the pipe strings, and set in elevation with respect to the first two rollers, for rotating the inner pipe string 52 during pipe-in-pipe assembly. The rollers 222, 224 are height adjustable to optimize the inner to outer pipe string offset during assembly. Additionally, the parallel set of motorized rollers 224 can be moved such that they make no contact with any pipe surface, to allow the outer pipe string 54 to pass. The height of the rollers is adjustable through a hydraulic system, while the motorized rollers may have electro motors. To support a quad-joint pipe-in-pipe string during assembly, a minimum of four motorized pipe line-up conveyor modules 220 may be required.

[0062] FIG. 9 shows a schematic cross-section of the pipe strings in the push-pull system 200 tool during pipe-in-pipe assembly, with pipe end pusher 240, end caps 250, 252 and winches 242, 248 with winch wires 243 and 249. Inside the push-pull system 200 an inner pipe string 52 and an outer pipe string 54 have been placed for pipe-in-pipe assembly, whereby the inner pipe string has centralizers 53 located on its outer diameter. The inner pipe string 52 has the inner pipe end cap 250 placed on its first end, while its second end is inserted into the outer pipe string 54. The outer pipe string 54 has the outer pipe end cap 252 fitted to its end located farthest away from the inner pipe string 52. The inner and outer pipe end caps 250, 252 are made from soft material to ensure they do not damage the pipe ends during pipe-in-pipe assembly operations, whereby each end cap is a tailor-made tool machined to fit a specific pipe string end diameter size. The pipe end pusher 240 is equipped with an inner pipe end cap 250. The inner pipe end cap 250 is provided with a passage by which a wire 243 of the inner pipe winch 242, can pass through both the inner pipe string 52 and the outer pipe string 54 and connect to the inner side of the outer pipe end cap 252. The external facing side of the outer pipe end cap 252 is connected at a second side of the workstation, normally the stern side, to an outer pipe winch 248. Operators of the system ensure the installation of the end cap system and adjust the pipe end pusher 240 to the inner pipe end string in elevation and transversal position. The insertion is initiated with a combination of the motorized rollers 224 described for FIG. 8 and the winch system. The initiation of insertion is completed when a minimum pressure is applied to the pipe end by the pipe pusher 240. At this stage, the operator switches the winch system from the controlled tension mode to a constant tension mode and the insertion is performed using only the motorized rollers 224 supporting the outer pipe string. The pipe-in-pipe centralizers 53, which have been preinstalled onto the inner pipe string 52 prior to pipe-in-pipe assembly assure a constant gap between the inner pipe string 52 and the outer pipe string 54.

[0063] The invention has been described with reference to the preferred embodiment. Obvious modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims.