RUNNING A SUBSEA RISER STRING

Abstract

A vessel is adapted to perform subsea wellbore related operations, involving a riser string that extends between a subsea wellbore and a vessel and that is assembled from releasably interconnected riser sections that each comprise a main riser pipe and at least one auxiliary pipe. The vessel includes an auxiliary pipe filling device adapted to fill the at least one auxiliary pipe of a riser section during a lowering step of said riser running operation, the auxiliary pipe filling device including a liquid source, e.g. for water, at least one nozzle adapted to dispense water into said auxiliary pipe, a liquid flow line, connecting the liquid source with the nozzle, and a nozzle mount that is adapted to mount the nozzle in a filling position in which the nozzle is positioned to dispense liquid into the at least one auxiliary pipe of the riser section during said lowering step.

Claims

1. Vessel (1) adapted to perform subsea wellbore related operations, involving a riser string (2) that extends between a subsea wellbore and the vessel and that is assembled from releasably interconnected riser sections (2A, 2B) that each comprise a main riser pipe (20) and at least one auxiliary pipe (21, 22), said vessel comprising a floating hull (3), a riser storage (4), and a tower (6) fixed to said hull (3) and defining a firing line (7), said vessel further comprising: a vertical handling system (8) comprising: a riser string lifting tool (11) adapted to connect to a top end (23) of a riser section (2A, 2B), and embodied to support the weight of the riser string (2), and a hoisting device (12) by which said riser string lifting tool (11) is suspended from the tower (6) and which hoisting device (12) is adapted to move the riser string (2) connected thereto via the riser string lifting tool (11) up and down relative to the tower (6), a riser spider device (15) that is adapted to temporarily suspend therefrom a riser string (2) into the sea at least during a riser running operation, the riser spider device (15) having a riser string passage therein through which the riser string (2) passes, wherein the riser running operation comprises a securing step wherein a new riser section (2A, 2B) held by the vertical handling system (8) is secured on top of said suspended riser string (2) and wherein the riser running operation comprises a lowering step wherein the vertical handling system (8) lowers the riser string (2) so that the top end thereof moves down relative to the tower (6) when the riser spider device (15) is disengaged from the riser string (2), said vessel (1) further comprising: an auxiliary pipe filling device (16) adapted to fill the at least one auxiliary pipe (21, 22) of a riser section (2A, 2B) with a liquid during said lowering step of said riser running operation, the auxiliary pipe filling device (16) comprising: a water or other liquid source (161), e.g. a reservoir and/or a water pump; at least one nozzle (162) adapted to dispense said water or said other liquid into said auxiliary pipe (21, 22); a liquid flow line (163), e.g. a hose, the liquid flow line (163) connecting the water or other liquid source (161) with the nozzle (162), and a nozzle mount (164), adapted to mount the nozzle (162) in a filling position in which the nozzle (162) is positioned to dispense water or other liquid into the at least one auxiliary pipe (21, 22) of the riser section (2A, 2B) during said lowering step.

2. Vessel according to claim 1, wherein the nozzle mount (164) is configured to be releasable fixed to a top end (23) of the riser section (2A, 2B), e.g. to the auxiliary pipe (21, 22).

3. Vessel according to claim 1, wherein the nozzle mount (164) is arranged on, or is configured to be arranged on, the riser string lifting tool (11) of the vertical handling system (8).

4. Vessel according to one or more of the preceding claims, wherein the nozzle mount (164) is provided with a positioning member which is to be mated with a portion of a top end of the riser section (2A, 2B), e.g. inserted in a slot or opening in a flange (18) of a riser section (2A, 2B), to position and/or secure the auxiliary pipe filling device (16) on the riser section (2A, 2B).

5. Vessel according to one or more of the preceding claims, wherein the at least one nozzle (162) is movably supported by the nozzle mount (164), such that the at least one nozzle (162) can be moved between the filling position and a non-operative position, in which filling position the at least one nozzle (162) is positioned adjacent to or partially inserted into an open top end (23) of the at least one auxiliary pipe (21, 22) of a riser section (2A, 2B), and in which non-operative position the at least one nozzle (162) is positioned away from the open end (23) of the at least one auxiliary pipe (21, 22).

6. Vessel according to one or more of the preceding claims, wherein the nozzle (162) is configured to be, at least partially, inserted in an open end (23) of the at least one auxiliary pipe (21, 22).

7. Vessel according to one or more of the preceding claims, wherein the nozzle (162) is configured to be coupled with an open end (23) of the at least one auxiliary pipe (21, 22), e.g. is provided with a stab connector or with a connector sleeve that can be coupled with an inner or outer screw thread section of the auxiliary pipe (21, 22).

8. Vessel according to one or more of the preceding claims, wherein the auxiliary pipe filling device (16) is provided with a valve, preferably a hydraulically actuated valve, which valve can be remotely operated such that the valve can be opened when the riser section (2A, 2B) is engaged by the riser string lifting tool (11) and in an upended position, to enable the auxiliary pipe (21, 22) to be filled while the riser section (2A, 2B) is being lowered along the firing line (7).

9. Vessel according to one or more of the preceding claims, wherein the liquid flow line (163) is flexible, and wherein the riser string lifting tool (11) is provided with a liquid flow line support (19) that is configured to support at least a section of the liquid flow line, preferably a support (19) that allows for removal of the liquid flow line (163) from the support (19) when the filling device (16) is not in use.

10. Vessel according to one or more of the preceding claims, wherein, when the riser string lifting tool (11) is in a lifted position and supports a new riser section (2A, 2B) in the firing line (7) above the riser spider (15), the liquid flow line (163) extends from the working deck to the top end (23) of the riser section (2A, 2B) supported by the riser string lifting tool (11).

11. Vessel according to one or more of the claims 1-9, wherein, when the riser string lifting tool (11) is in a lowered position in which it is located near the riser spider (15), the liquid flow line (163) extends from a top end of the tower (6) to the top end (23) of the riser section (2A, 2B) supported by the riser string lifting tool (11).

12. A riser string lifting tool (11) comprising a nozzle mount (164) and/or a nozzle (162) of an auxiliary pipe filling device (16) adapted to fill at least one auxiliary pipe (21) of a riser section (2A, 2B) during a lowering step of a riser running operation, wherein the auxiliary pipe filling device (16) further comprises: a water or other liquid source (161), e.g. a reservoir and/or a water pump; a liquid flow line (163), e.g. a hose, the liquid flow line (163) connecting the water or other liquid source (161) with the nozzle (162), wherein the nozzle (162) is adapted to dispense said water or said other liquid into said auxiliary pipe, and wherein the nozzle mount (164) is adapted to mount the nozzle (162) in a filling position in which the nozzle (162) is positioned to dispense water or other liquid into the at least one auxiliary pipe (21, 22) of the riser section (2A, 2B) during said lowering step.

13. A method for running of a subsea riser string (2) by interconnection of riser sections (2A, 2B), preferably using a vessel according to one or more of the preceding claims 1-11 and/or a riser string lifting tool according to claim 12, to compose a riser string (2) that extends between a vessel (1) and a subsea wellbore, wherein the riser string (2) is assembled from releasably interconnected riser sections (2A, 2B) that comprise a main riser pipe (20) and at least one auxiliary pipe (21, 22), the method comprising the steps: engaging a top end (23) of the riser section (2A, 2B) with a riser string lifting tool (11), positioning a nozzle (162) in a filling position at a top end (23) of the at least one auxiliary pipe (21, 22) of the riser section (2A, 2B); securing a rear end of the riser section (2A, 2B) with a top end of the riser string (2); and filling the at least one auxiliary pipe (21, 22) using the nozzle (162) while lowering the riser section (2A, 2B) and the riser string (2) connected thereto.

14. A method according to claim 13, the method further comprising installing a blowout preventer stack (BOP), wherein the riser section (2A, 2B) comprises a main riser pipe (20) and two or more auxiliary pipes (21, 22) on the outside of and along the main riser pipe (20), and wherein the two or more auxiliary pipes (21, 22) are to be used as choke/kill lines extending from a vessel (1) to the BOP located at the sea floor, the method comprising the steps: moving a BOP to a position in the firing line (7), and moving a first riser section (2A) including choke/kill lines (21, 22) in the firing line (7), the riser section (2A) being positioned above the BOP; connecting the first length of the main riser pipe (20) and the two or more choke/kill lines (21, 22) to said BOP.

Description

[0064] The invention will now be described in more detail with reference to the drawings. In the drawings:

[0065] FIG. 1 schematically shows a vessel according to an embodiment of the invention,

[0066] FIG. 2 schematically shows a detailed view of a top end of a tower, comprising a riser string lifting tool, a riser section, and a first embodiment of the auxiliary pipe filling device,

[0067] FIG. 3 schematically shows a detailed view of a top end of a tower, comprising a riser string lifting tool, a riser section, and a second embodiment of the auxiliary pipe filling device,

[0068] FIG. 4 schematically shows riser string lifting tool, a riser section and a third embodiment of the auxiliary pipe filling device,

[0069] FIG. 5 schematically shows a top view of a riser section comprising auxiliary pipes.

[0070] FIG. 1 schematically shows a vessel 1 adapted to perform subsea wellbore related operations, e.g. drilling and/or wellbore intervention, involving a riser string 2 that extends between a subsea wellbore and a vessel. The riser string 2 is assembled from releasably interconnected riser sections 2A that each comprise a main riser pipe and at least one auxiliary pipe on the outside of and along, e.g. parallel to, the main riser pipe. An exemplary embodiment of a riser section 2A will be described more elaborately below with reference to FIG. 5.

[0071] In the embodiment of FIG. 1, the vessel comprises a floating hull 3, here of the mono-hull type. The vessel further comprises a riser storage 4 adapted to store therein multiple risers sections 2B, e.g. riser section having a length of between 50 ft. and 180 ft., such as riser sections having a length of 75 ft., 90 ft., or 150 ft.

[0072] The vessel further comprises a moonpool 5 in said hull 3 and a tower 6 arranged at said moonpool 5 and fixed to said hull 3, the tower 6 defining a firing line 7 along which the riser string 2 is launched towards the subsea wellbore.

[0073] The vessel 1 further comprises a vertical handling system 8, here a riser string vertical handling system, the riser string vertical handling system here comprising a travelling device 9, a riser string lifting tool 11, and a hoisting device (see FIGS. 2 and 3). The travelling device 9 is movable up and down along the tower 6. It may for example be guided by one or more vertical rails 10 mounted on said tower 6, the travelling device 9 e.g. being a wheeled travelling device having wheels engaging said one or more vertical rails 10.

[0074] The vessel further comprises a riser spider device 15 that is supported above the water in the moonpool 5 and that is adapted to temporarily suspend therefrom a riser string 2 into the sea at least during the riser running or assembly process. The riser spider device 15 has a riser string passage therein through which the riser string 2 can pass, wherein the riser spider device 15 is preferably mounted on a working deck which extends, e.g. in an operative position thereof, above at least an area of the water in the moonpool 5.

[0075] The riser running operation comprises a securing step wherein a new riser section 2A, 2B held by the vertical handling system 8 is secured on top of said suspended riser string 2 and wherein the riser running operation comprises a lowering step wherein the vertical handling system 8 lowers the riser string 2 so that the top end thereof moves down relative to the tower 6 when the riser spider device 15 is disengaged from the riser string 2,

[0076] As is clearly visible in FIGS. 2 and 3, the riser string lifting tool 11 is mounted on said travelling device 9 and is adapted to connect to a top end 23 of a riser section 2B, the riser string lifting tool 11 being embodied to support the weight of the riser string. The travelling device 9 and the riser string lifting tool 11 are suspended from the tower 6 by the hoisting device 12, the hoisting device 12 being adapted to move the riser string 2, when it is connected thereto, via the riser string lifting tool 11 and in unison with the travelling device 9 up and down relative to the tower 6.

[0077] As shown, the hoisting device 12 comprises a winch 13 and a winch driven cable 14, wherein the riser string lifting tool 11 and the travelling device 9 are suspended from said at least one cable 14.

[0078] Further visible in FIGS. 2 and 3, are embodiments of an auxiliary pipe filling device 16 that is configured to least partially fill the at least one auxiliary pipe 21, 22 of a riser section 2B during said lowering step of the riser running operation, the auxiliary pipe filling device 16 comprising a water or other liquid source 161, here a water source 161, e.g. a reservoir and/or a water pump, at least one nozzle 162 for dispensing water into said auxiliary pipe 21, 22, a liquid flow line 163, e.g. a drape hose, and a nozzle mount 164. The liquid flow line 163 connects the water source 161 with the nozzle 162 and preferably has a length larger than the length of a riser section 2A, 2B. The nozzle mount 164 mounts the nozzle 162 in a filling position in which the nozzle 162 is positioned to dispense water into the at least one auxiliary pipe 21, 22 of the riser section 2B during the lowering step.

[0079] FIGS. 2 and 3 show how the nozzle mount 164 can be fixed to the top end 23 of the riser section 2B. Here, the nozzle mount 164 is directly fixed to the auxiliary pipes 21, 22. This fixed connection is preferably releasable, allowing the auxiliary pipe filling device 16 to be used for a consecutive riser section, when there is a consecutive riser section, and allowing the top end 23 of the auxiliary pipes 21, 22 to be connected to a bottom end of auxiliary pipes of a consecutive riser section, when there is a consecutive riser section.

[0080] As FIG. 4 shows, it is not necessary to fix the nozzle mount 164 to the top end 23 of the riser section 2B. The nozzle mount 164 may not be fixed at all, the nozzles 162 simply extending into the auxiliary pipes 21, 22. The nozzle mount 164 may also be mounted onto the riser string lifting tool 11, as shown in the embodiment of FIG. 4. Yet other embodiments are conceivable, e.g. where the nozzle mount is releasably fixed to the travelling device.

[0081] For example, in a non-shown embodiment the nozzle mount is provided with a positioning pin which is to be inserted in a slot or opening in a flange of a riser section, to position and/or secure the auxiliary pipe filling device on the riser section.

[0082] As for example visible with respect to FIG. 4, the nozzles 162 may be movably supported by the nozzle mount 164. Here the nozzle mount 164 is an arm that is hingedly connected to the riser string lifting tool 11, which arm may be able to hinge with respect to a longitudinal axis of the riser string lifting tool 11, i.e. out of an imaginary plane spanned by the paper. This allows the nozzles 162 to be moved between the filling position and a non-operative or passive position, where a possible filling position is shown in FIG. 4, with each nozzle 162 positioned above an open top end 23 of a respective auxiliary pipe 21, 22 of the riser section 2B. In the passive position, the nozzles 162 are then positioned away from the open end 23 of the auxiliary pipes 21, 22.

[0083] In other embodiments, the movement of the nozzle mount between the filling position and the passive position may be achieved by an extending and/or retracting motion, and/or by an upwards and/or downwards sliding movement of the nozzle mounts. For example, the position shown in FIG. 4 may alternatively be the passive position, wherein the nozzle mounts 164 are slid downwards to bring the nozzles 162 into the auxiliary pipes 21, 22 and into the filling position. Hence, the nozzle 162 may be configured to be, at least partially, inserted in an open end 23 of the at least one auxiliary pipe 21, 22.

[0084] With reference to FIGS. 2 and 3, it is shown how the nozzle 162 is configured to be coupled with the open end 23 of the at least one auxiliary pipe 21, 22. The nozzles 162 here comprise a connector sleeve that can be coupled with an outer screw thread section of the auxiliary pipe 21, 22. The nozzle mount 164 is here then embodied as a connector sleeve.

[0085] In a conceivable, non-shown, embodiment, the auxiliary pipe filling device is provided with a valve or pump, such as a hydraulically actuated valve, which valve or pump can be remotely operated such that the valve or pump can be opened respectively activated when the riser section is engaged by the riser string lifting tool and in an upended position, to enable the auxiliary pipe to be filled while the riser section is being lowered along the firing line.

[0086] As shown with reference to FIGS. 2 and 3, the liquid flow line 163 may be flexible, where at least a section of the liquid flow line 163 may be supported by a liquid flow line support 19.

[0087] For example, the liquid flow line support 19 may be attached to the travelling device 9, as shown in FIG. 3, or to riser string lifting tool 11. Preferably, the support 19 is adapted to allow removal of the liquid flow line 163 from the support 19 when the filling device 16 is not in use. For example, with respect to the embodiment of FIG. 3, the nozzles 162 and nozzle mounts 164 may be releasable mounted onto the liquid flow line 163, such that they can be removed when the last riser section 2B of the riser string 2 is filled with water and is supported by the riser spider device. One can then pull the liquid flow line 163 through support 19, allowing removal of the liquid flow line 163 from the support 19 while the filling device 16 is not in use.

[0088] With respect to FIG. 2, it is shown how the water source 161 is arranged substantially below the top of the tower 6, preferably on or near deck level. When the riser string lifting tool 11 is now in a lifted position, as shown, and supporting the riser section 2B in the firing line above a working deck supporting the riser spider, the liquid flow line 163 extends from the working deck to the top end 23 of the riser section 2B supported by the riser string lifting tool 11.

[0089] With respect to FIG. 3, where a second embodiment of the auxiliary pipe filling device 16 is shown, with secondary or main water source 161 arranged near the top of the tower 6, it can be seen that the liquid flow line 163 partially extends downwards along the tower 6 when the riser string lifting tool 11 is in a lifted position. Instead of extending partially downwards along the tower 6, the liquid flow line 163 may, alternatively, be stored in a buffer, e.g. on a spool.

[0090] In the embodiment of FIG. 3, it will be clear that the liquid flow line 163, when the riser string lifting tool 163 is in the lowered position near the riser spider, extends from a top end of the tower 6 to the top end 23 of the riser section 2A 2B supported by said riser string lifting tool.

[0091] Shown with reference to FIG. 5 is a schematic top view of a riser section 2B, the riser section 2B comprising a main riser pipe 20, multiple auxiliary pipes 21, 22 distributed on the outside of, and along, the main riser pipe 20, and a flange 18. Besides a main riser section 20 and one or more auxiliary pipes 21, 22, riser sections 2B often also comprise buoyance means, arranged near an outer side of the section. The auxiliary pipe 21, 22 may be used as a liquid line, e.g. to a BOP or other subsea equipment, e.g. comprising water, or another fluid.

[0092] Shown in FIG. 4 is a riser string lifting tool 11 comprising a nozzle mount 164 and/or a nozzle 162 of an auxiliary pipe filling device 16 adapted to fill at least one auxiliary pipe 21 of a riser section 2A, 2B during a lowering step of a riser running operation, wherein the auxiliary pipe filling device 16 further comprises: [0093] a water source 161, e.g. a reservoir and/or a water pump; [0094] a liquid flow line 163, e.g. a hose, the liquid flow line 163 connecting the water source 161 with the nozzle 162, [0095] wherein the nozzle 162 is adapted to dispense water into said auxiliary pipe, and [0096] wherein the nozzle mount 164 is adapted to mount the nozzle 162 in a filling position in which the nozzle 162 is positioned to dispense water into the at least one auxiliary pipe 21, 22 of the riser section 2A, 2B during said lowering step.

[0097] Although certain embodiments of the auxiliary pipe filling device have been described in the above in relation to a vessel comprising an auxiliary pipe filling device, the same embodiments may be conceived for a riser string lifting tool comprising an auxiliary pipe filling device.

[0098] In use, when running a subsea riser string 2 by interconnecting multiple riser sections 2A, 2B as a first step a blowout preventer stack (BOP) (not shown) may be positioned in a firing line 7, e.g. at a moonpool of a vessel. A first riser section 2A including a main riser pipe 20 and choke/kill lines 21, 22 may consecutively be moved into the firing line 7, the riser section 2A being positioned above the BOP. As a third step, the first length of main riser pipe 20 and the two or more kill/choke lines 21, 22 are connected to the BOP. The BOP and riser section 2A are then released into sea, towards a subsea wellbore; the riser section 2A defining a riser string 2.

[0099] To elongate the riser string 2, a further riser section 2B may be connected to the riser string 2. Therefore, the riser section 2B, that is to be connected to the riser string 2, may be brought in a horizontal position near a tower 6. Then, a top end 23 of the riser section 2B may be engaged with a riser string lifting tool 11. Afterwards, a nozzle 162 may be positioned at a top end 23 of the auxiliary pipes 21, 22 of the riser section 2B, in a filling position of said nozzle 162. Then, the riser section 2B may be upended from its horizontal position towards its vertical position, into the firing line 7, after which a bottom end of the riser section 2B is connected to a top end of the riser string 2. Consecutively, the at least one auxiliary pipe 21, 22 may be filled using the nozzle 162, while the riser section 2B and the riser string 2 are lowered towards the subsea wellbore.

[0100] Hence, the invention further relates to a method for running of a subsea riser string 2 by interconnection of riser sections 2A, 2B, preferably using a vessel and/or a riser string lifting tool according to the invention, to compose a riser string 2 that extends between a vessel 1 and a subsea wellbore, e.g. in a drilling and/or wellbore intervention operation, wherein the riser string 2 is assembled from releasably interconnected riser sections 2A, 2B that comprise a main riser pipe 20 and at least one auxiliary pipe 21, 22, the method comprising the steps: [0101] engaging a top end 23 of the riser section 2A, 2B with a riser string lifting tool 11, [0102] positioning a nozzle 162 in a filling position at a top end 23 of the at least one auxiliary pipe 21, 22 of the riser section 2A, 2B; [0103] connecting a rear end of the riser section 2A, 2B with a top end of the riser string 2; and [0104] filling the at least one auxiliary pipe 21, 22 using the nozzle 162 while lowering the riser section 2A, 2B and the riser string 2 connected thereto.