GB2468040A

GB2468040A - A subsea protective structure

Info

Publication number: GB2468040A
Application number: GB201002887A
Authority: GB
Inventors: H Kon Weum; Arnt Frode Brevik; Lars Espen Holm
Original assignee: COMPOCEAN AS
Current assignee: COMPOCEAN AS
Priority date: 2009-02-19
Filing date: 2010-02-19
Publication date: 2010-08-25
Also published as: NO20090798L; GB201002887D0; NO330817B1

Abstract

A structure for protecting subsea equipment includes a roof 10 comprising at least one roof plate element 10a, 10b, 10c for protecting the subsea equipment from above. A supporting beam element 20 supports the roof 10. The supporting beam element 20 comprises a cross member 21 and two end members 22 protruding substantially downwardly from the cross member 21. A leg element 30 is provided on the respective ends of the end members 22 of the supporting beam element 20, for fixing the protection structure to a foundation. A distance La between the end members 22 of the supporting beam element 20 increases with the distance Ha from the cross member 21, fig 8.

Description

FIELD OF THE INVENTION

The present invention relates to a protection structure for protecting subsea equipment provided on the seabed.

BACKGROUND

Subsea equipment, such as pipelines, cables, pipeline connections, spools, riser bases, tee's, etc. located on the seabed in connection with oil and gas recovery is subjected to dropped objects and in some cases trawis loads. The solution is often some kind of protection covers in the form of composites covers that are made in one piece or welded steel covers. The composite covers usually are of a tunnel type with skew sides and a flat roof. The steel structures are open structures with welded beams or profiles.

The disadvantage of these protection covers are that they are heavy and/or occupies space. In most occasions such protection covers must be transported from the production facility to the site by means of a ship. This is an expensive and cumbersome operation.

The object of the invention is to provide a protection structure that can be transported in an efficient manner. More specific, it is an object of the invention to provide a protection structure that can be transported in a disassembled state, where the assembly of the protection structure can be performed near the site.

SUMMARY OF THE rNVENTION

The object is achieved with a protection structure according to independent claim 1.

Aspects of the invention are defined in the dependent claims.

DETAILED DESCRIPTION

In the following, preferred embodiments of the invention will be described in detail with reference to the enclosed drawings, where: Fig. 1 illustrates a first embodiment of the protection structure in an assembled state; Fig. 2 illustrates the first embodiment of the protection structure in a disassembled state; Fig. 3 illustrates a second embodiment of the protectioi structure in an assembled state; Fig. 4 illustrates the second embodiment of the protection structure in a disassembled state; Fig. 5 illustrates two protection structures according to fig. 1 assembled in their longitudinal direction; Fig. 6 illustrates the supporting beam element viewed in a plane perpendicular to the longitudinal axis I-I of the protection structure; Fig. 7 illustrates a cross sectional view of the supporting beam element along line A-A in fig. 6; Fig. 8 illustrates a simplified view of fig. 6; Fig. 9 illustrates a simplified view of section B of fig. 7; Fig. 10 -13 illustrates stacking of the supporting beam element and the protection structure respectively; Fig. 14 illustrates a third embodiment of the protections structure in assembled state.

First embodimeiit It is now referred to fig. I and 2, illustrating a first embodiment of a protection structure I for protecting subsea equipment (not shown) provided on the seabed.

The protection structure 1 is fixed to a foundation, for example the seabed itself, or another type of foundation, such as a pipe line foundation etc. In the present embodiment, the protection structure is primarily used for protection of longitudinal subsea equipment, for example a pipeline. Hence, the protection structure shown in fig. 1 may be serially connected to similar protection structures in its longitudinal direction I -I, as indicated in fig. 5.

The protection structure comprises a roof 10, a supporting beam element 20 and a leg element 30.

The roof 10 comprises at least one roof plate element 10 for protecting the subsea equipment from above, i.e. from dropped objects etc. in the embodiment shown in fig. 1, there are three roof elements: a first roof element lOa, a second roof element lOb and a third roof element lOc respectively. The roof plate elements lOa, lOb, lOc may comprise connection interfaces in a direction perpendicular to the longitudinal direction I -I for connection of the roof plate elements to each other.

As shown in fig. 2, a first connection interface 11 of the first roof plate element lOa is provided for connection to a first interface 12 of the second roof plate element lOb. Moreover, a second connection interface 13 of the second roof plate element lOb is provided for connection to a first interface 14 of the third roof plate element 1 Oc. As shown, these three roof plate elements are connected to each other in a first direction perpendicular to the longitudinal direction 1-I. In the present embodiment, these connection interlaces comprises an upwardly protruding part of the roof plate elements, wherein several holes are provided. Hence, screws, rivets etc may be used to connect the roof plate elements to each other. Alternatively, they may be glued, welded or fastened to each other in other ways.

The roof plate elements lOa, lOb, lOc may comprise also connection interfaces in a second direction parallel to the longitudinal direction I -I for connection of several protection structures to each other in a longitudinal direction, as described above. In fig. 1 and 5 it is shown that a first longitudinal end 15 of the roof 1 slopes downwardiy. Hence, as shown in fig. 5, the first longitudinal end 15 of a first protection structure may be placed under a second longitudinal end 16 of a second protection structure. Consequently, the roofs of the first and second protection structures overlap each other when mounted on the seabed, and a hence a long, continuous protection structure is achieved. The overlap zone may also contribute to the overall stability for the assembled protection structure, by transferring load from one protection structure to adjacent protection structures. The overlapping zone could for example have a length of typically 0.5 -Im.

The roof plate elements may of course comprise be interconnected in several alternative ways.

In the present embodiment, the roof plate elements are made of composite materials, such as fibre reinforced plastic. Alternatively, they may be made of metal plates.

The supporting beam element 20 is supporting the roof 10. The supporting beam element 20 comprises a cross member 21 and two end members 22 protruding substantially downwardly from the cross member, as shown the drawings. The supporting beam element 20 may consequently viewed as being substantially U-shaped when viewed in a plane perpendicular to the longitudinal axis I-I of the protection structure. The substantially U-shaped supporting beam element 20 can also be seen in fig. 6 and 8 (where axis I-I is illustrated as being perpendicular to the drawing plane).

In fig. 8 it is shown that a distance La between the end members 22 of the supporting beam element is increasing with the distance Ha from the cross member 21, i.a. the distance Lal near the cross member 21 is less than the distance La2 near the ends of the end members 21. in other words, an angle na between the cross member 21 and the respective end members 21 is less than 900, for example between45°-85°.

Consequently, the supporting beam elements 20 are well suited for being stacked together in an efficient manner during transport, since the supporting beam elements may be "inserted into" each other.

Moreover, the cross member 21 and the end members 22 comprise a cross surface 23 and two end surfaces 24 protruding from the cross surface 23. These members may consequently be viewed as being substantially U-shaped as viewed in their respective cross sectional planes. The substantially U-shaped cross section of the cross member 21 along line A-A of fig. 6 can for example be seen in fig. 7 and fig. 9. Fig. 9 is an enlarged view of section 13 in fig. 7.

In fig. 9 it is shown that a distance Lb between the end surfaces 24 of the respective members 21, 22 is increasing with the distance Hb from the cross surface 23, ie. the distance Lb 1 near the cross surface 23 is less than the distance Lb2 near the ends of the end surfaces 24. In other words, an angle ab between the cross surface 23 and the respective end surfaces 24 is less than 900, for example between 450 -85°.

Consequently, the supporting beam elements 20 are even better suited for being stacked together in an efficient manner during transport, since they can be stacked even closer to each other. In fig. 10 it is shown how the end members 22 can be inserted into each other. In fig. 11 it is shown how the end members 22 arid the cross members 21 can be inserted into each other.

This type of stacking will typically be used for transportation of the disassembled protection structure from the production facility to for example a harbour near the site. Hence, the transportation of the disassembled protection structure may be performed by a trailer truck. On the harbour, the protection structure may be assembled, and shipped to the site by means of a ship. In assembled state, the protection structures may be stacked as shown in fig. 12 and 13.

In the present embodiment, the supporting beam element 20 is made of composite materials, such as fibre reinforced plastic. Alternatively, they may be made of metal.

The leg element 30 is provided on the respective ends of the end members 22 of the supporting beam element 20, for fixation of the protection structure 1 to the foundation. The leg element 30 may be substantially U-shaped in cross section for mounting to the lower part of each end member 22.

The leg element may comprise a fixation interface for fixation of the leg element to the foundation, for example a plate dimensioned for the required weightlload acting on the foundation.

Moreover, the protection structure 1 may comprise a ballast element 40 for baflasting the protection structure. The ballast element 40 can be fixed to the protection structure 1, for example to the roof 10 (as in the embodiment in fig. 3), or to the end members 22 of the supporting beam structure 20 (as in the embodiment in fig. 1) or to the leg elements 30. It should be noted that the protection structure can be considered fixed to the foundation only by adding the ballast element 40 to it.

The ballast element 40 comprises longitudinal ballast members 41, for example steel bars or steel plates. In this way it would be easy to control the correct amount of ballast to the protection structure.

The ballast element 40 may comprise a fixation device 42 for fixation of the ballast element 40 to the protection structure 1.

Moreover, the protection structure may comprise side plate elements (not shown) for protecting the subsea equipment from aside.

The ballast element 40 may also be fixed to the leg elements 30.

0 Secopd embodiment It is now referred to fig. 3 and 4, where a second embodiment of the invention is illustrated, in the second embodiment, the same reference numbers are used as in the first embodiment above for equal or similar elements, and they will not be described here in detail.

In the second embodiment, the roof 10 comprises three roof plate elements I Oa, lOb, lOc that comprises connection interfaces in a direction perpendicular to the longitudinal direction I -I for connection of the roof plate elements to each other.

However, in this embodiment the roof plate elements lOa, lOb, lOc do not comprise connection interfaces in a second direction parallel to the longitudinal direction I - 1. Hence, the roofs of two adjacent protection structures do not overlap, they are only placed against each other.

Moreover, in this embodiment the end members 22 of the supporting beam element are shorter than in the first embodiment. However, the angles a8 and ab are similar to the first embodiment described above. Consequently, also the supporting beam element 20 according to this embodiment is well suited for efficient transportation.

Third erndimen It is now referred to fig. 14, illustrating a third embodiment of the protection structure. In the third embodiment, the same reference numbers are used as in the first and second embodiments above for equal or similar elements, and they will not be described here in detail. Here, the leg elements 30 comprises sliding or skidding bodies, suitable for pulling the protection structure along the seabed. Moreover, one or several ring elements 50 are fixed to the protection structure for connection to pulling wires etc. Oter alterpative embodjmeit In fig. 1 it is shown that two supporting beam elements 20 are used to support the roof 10. It should be noted that the number of supporting beam elements 20 may vary depending on the size of the roof and other technical requirements etc. Since several protection structures I may be assembled together, it would also be possible to use only one supporting beam element 20.

Moreover, the embodiments above may have equal or different distances between the end members of the supporting beam element.

Claims

CLAIMS1. Protection structure for protecting subsea equipment provided on the seabed, where the protection structure is fixed to a foundation, where the protection structure further comprising: -a roof (10) comprising at least one roof plate element (1 Oa, I Gb, I Oc) for protecting the subsea equipment from above; -a supporting beam element (20) for supporting the roof (10), comprising a cross member (21) and two end members (22) protruding substantially downwardly from the cross member; -a leg element (30) provided on the respective ends of the end members (22) of the supporting beam element (20), for fixation of the protection structure to the foundation; wherein the distance La between the end members (22) of the supporting beam element is increasing with the distance Ha from the cross member (21).
2. Protection structure according to claim 1, wherein the cross member (21) and the end members (22) comprise a croSs surface (23) and two end surfaces (24) protruding from the cross surface (23).
3. Protection structure according to claim 2, wherein the distance Lb between the end surfaces (24) is increasing with the distance Jib from the cross surface (23).
4. Protection structure according to any one of the claims above, wherein a first roof plate element (1 Oa) comprises a first connection interface for connection to a second roof plate element (lOb) in a first direction.
5. Protection structure according to claim 4, wherein the first roof plate element (1 Ga) comprises a second connection interface for connection with an adjacent first roof plate element (1 Ga) in a second direction.
6. Protection structure according to any of the claims above, wherein the leg element is substantially U-shaped in cross section.
7. Protection structure according to any of the claims above, wherein the leg element comprises a fixation interface for fixation of the leg element to the foundation.
8. Protection structure according to claim 1, wherein the protections structure comprises a ballast element (40) for ballasting the protection structure.
9. Protection structure according to claim 8, wherein the ballast element (40) comprises longitudinal ballast members fixed to the roof (1).
10. Protection structure according to claim 8, wherein the ballast element (40) comprises longitudinal ballast members fixed to the end members (22).
11. Protection structure according to any one of claim 8 -10, wherein the ballast element comprises a fixation device for fixation of the ballast element (40) to the protection structure.
12. Protection structure according to any of the claims above, wherein the supporting structure comprises side plate elements for protecting the subsea equipment from aside.