SUBSEA ASSEMBLY MODULARIZATION

Abstract

A foundation for a subsea assembly is provided. The foundation includes connection points. The connection points permit other components to be connected to the foundation and permit loads to transfer from the other components into the foundation. The foundation may be a suction anchor. A method of converting an exploration well using the foundation to a production well is also provided.

Claims

1. A method of converting an exploration well into a production well, the method comprising: providing a subsea well assembly, the well assembly comprising a foundation, wherein the foundation comprises one or more connection points, using the subsea well assembly as an exploration well assembly; and converting the exploration well assembly to a production well assembly, wherein converting the exploration well assembly to a production well assembly comprises connecting one or more components to the foundation via the one or more connection points.

2. A method according to claim 1, wherein no components are connected to the one or more connection points when the well assembly is being used as an exploration well.

3. A method according to claim 1, wherein the one or more components comprises a support device and/or a subsea equipment adapter frame and wherein converting the exploration well assembly to a production well assembly comprises installing the support device and/or the subsea equipment adapter frame on the foundation.

4. A method according to claim 1, comprising determining whether the exploration well assembly is in a location desired for a production well.

5. A method according to claim 1, wherein providing the subsea well assembly comprises installing the subsea well assembly using the one or more connection points as lift points.

6. A method according to claim 1, comprising using the one or more connection points to connect components mounted on a well head.

7. A method according to claim 1, comprising using the one or more connection points to connect a protection structure to protect the subsea well assembly.

8. A method according to claim 1, wherein the one or more connection points permit other components to be connected to the foundation and permit loads to transfer from the component connected to the connection points into the foundation.

9. A method according to claim 1, wherein the foundation comprises a plurality of connection points and wherein the connection points are provided at approximately equally spaced locations around the outer perimeter of the foundation.

10. A method according to claim 1, wherein the foundation is a suction anchor.

11. A method according to claim 1, wherein the one or more connection points are additional parts that protrude from the foundation to provide an attachment point for components to be mounted on the foundation.

12. A method according to claim 1, wherein one or more of the connection points has an adjustable height.

13. A method according to claim 1, wherein each connection point comprises or is arranged to be connected to a guide device.

14. A method according to claim 1, wherein the one or more connection points are stronger than the adjacent parts of the foundation.

15. A method according to claim 1, wherein one or more of the connection points is provided at the outer perimeter of the foundation.

16. A method according to claim 1, wherein one or more of the connection points extends beyond the top of the foundation.

17. A method according to claim 1, wherein one or more of the connection points is integral with the foundation.

18. A method according to claim 1, wherein one or more of the connection points has a profile that permits load transfer and/or locking of the component that is connected to the connection point.

19. A method according to claim 1, wherein each connection point comprises a base portion integral with the foundation and a connection portion to which a component can be attached.

20. A keeper well convertible from an exploration well to a production well according to the method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0149] Certain preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0150] FIG. 1 is a perspective view of the top of a first subsea well assembly;

[0151] FIG. 2 is a side view of a second subsea well assembly;

[0152] FIG. 3 is a side view of a third subsea well assembly;

[0153] FIG. 4 is a perspective view of a fourth subsea well assembly;

[0154] FIG. 5 is a perspective view of a fifth subsea well assembly;

[0155] FIG. 6 is a side view of a sixth subsea well assembly;

[0156] FIG. 7 is a side view of a seventh subsea well assembly; and

[0157] FIG. 8 is a side view of an eighth subsea well assembly.

DETAILED DESCRIPTION OF THE INVENTION

[0158] FIG. 1 shows part of a subsea well assembly 1. Whilst the invention is described in relation to a subsea wellhead assembly, many aspects of the invention (except those specifically related to the features of wells) are applicable to other subsea assemblies that comprise a foundation. Thus, the following description should be understood where appropriate to apply to any subsea assembly with a foundation. The subsea well assembly 1 comprises a foundation 2 which in this case is a suction anchor. The suction anchor 2 comprises an outer suction skirt 4 around a central tube and a top plate 6 connecting the outer suction skirt to the central tube to form an internal volume inside the suction anchor 2 that is a sealed volume when the suction anchor 2 is on the sea floor and has penetrated the sea floor slightly. This penetration may be due to its own weight or due to putting extra downward force on the top of the suction anchor 2 when it is resting on the seafloor.

[0159] The suction anchor 2 may be sucked into the sea floor by reducing the pressure inside the suction anchor 2 to thereby provide a subsea well foundation in the seabed.

[0160] The central tube may be or receive a low pressure wellhead housing 8 in which is received a high pressure wellhead housing 10.

[0161] The suction anchor 2 comprises a plurality (there are four in the example of FIG. 1) of integral connection/strong points 12. These connection points 12 are stronger than the adjacent parts of the suction anchor 2 and provide a strong point for components to be connected to the suction anchor 2 such that load can be transmitted into the suction anchor 2 and thus into the sea floor. The connection points 12 are located equally spaced around the top of the suction skirt 4 of the suction anchor 2. The connection points 12 are integral (e.g. welded or integrally formed) with the suction anchor 2. Each connection point has a base portion 14 and a connection portion 16. The base portion 14 is fixed to the suction anchor 2 (e.g. on the suction skirt). The connection portion 16 protrudes from the top of the suction anchor 2 and provides a part to which other components such as a support frame can be connected. The connection portion 16 may also comprise a receptacle for receiving a guiding device such as guide post 20 as shown in FIG. 2.

[0162] The receptacle may have a standard interface to allow it to be locked to the component it receives and for loads to be transferred from the component into the connection points.

[0163] The assembly 1 in FIG. 1 shows a wellhead support 17 mounted on the suction anchor 2. The wellhead support 17 is external of the internal volume of the suction anchor 2. The wellhead support 17 may connected to the suction anchor 2 via the connection points 12 and/or be directly attached to the top plate 6. The wellhead support 17 may for example be welded to the connection points 12 and/or the top plate 6. The wellhead support 17 may also support the connection points 12.

[0164] The wellhead support 17 may rest on the top plate 6 of the suction anchor 2. The wellhead support 17 may have a plurality of wellhead support members 22 (in this case eight). The wellhead supports 22 may provide lateral support to the wellhead 8 and allow the transfer loads from the wellhead 8 into the suction anchor 2. The wellhead supports 22 each comprise vertical plates (e.g. I-beams) that are spaced around the circumference of the wellhead 8 outside of the internal volume of the suction anchor. This allows the wellhead support members to provide lateral support to the wellhead 8 distributed around its circumference whilst leaving parts of the wellhead 8 exposed for wellhead interventions. The wellhead supports 22 may be connected via an outer frame 24. Thus the wellhead support 17 may comprise the wellhead supports 22 and the outer frame 24. The outer frame 24 may rigidly connect the wellhead support members 22 and be used to connect the wellhead support 17 to the suction anchor 2 via the connection points 12.

[0165] The well support 17 may also comprise one or more receptacles 26 for receiving guide devices 20 (e.g. guide posts). These protruding members 20 may provide a means to which components can be attached, a means for transferring loads (such as lateral loads from components mounted on the assembly 1 to the suction anchor 2), a means for guiding the components into the correct position and orientation on the suction anchor 2 and/or a means to which guide wires 28 can be attached during an installation procedure (as shown for example in FIG. 2).

[0166] The well support 17 may be integral with the suction anchor or a separate modular component from the suction anchor 2 and may be installed separately from the suction anchor 2.

[0167] The well support 17 may provide a surface on which components mounted on the subsea assembly 1 may rest. For example, equipment support structure 29 or subsea equipment adapter frame 30 may be located on the wellhead support 17. The subsea equipment adapter frame 30 may be a separate modular component from the suction anchor 2 and the well support 17 and/or the equipment support structure 29 and may be installed separately from the suction anchor 2 and equipment support structure 29.

[0168] A suction anchor 2 with connection points 12 may be installed and used as an exploration well. If it is desired to convert the suction anchor 2 from an exploration well to a production well this may be possible by using the connection points 12 to connect equipment support structure 29 and subsea equipment adapter frame 30 to the suction anchor 1.

[0169] To install the equipment support structure 29 and/or the subsea equipment adapter frame 30 on a preinstalled suction anchor 2, guide posts 20 may be installed on/in the connection portions 16 of the connection points 12 (see for example FIG. 2). Guide wires 28 may be connected to the guide posts 20. The guide wires 28 may be passed through apertures in the equipment support structure 29 and subsea equipment adapter frame 30 and used to guide these components into roughly the correct location above the wellhead and onto the guide posts 20.

[0170] As shown in FIGS. 2,3, 6 and 7 for example, one of the guide posts 20 may be longer than the other guide posts 20. This is so that this longer guide post 20 is received first in an aperture in the component being mounted and at that point provides a point about which the component can be rotated to get it in the correct location to be received by the other guide posts 20. This may make the installation easier as first the component can be translated to align an aperture with the longer guide post 20 and then rotated to align the other apertures with the other guide posts 20.

[0171] Once the component (e.g. the equipment support structure 29 and/or the subsea equipment adapter frame 30) being mounted has been roughly aligned relative to the wellhead 10 using the guide posts 20, the component may be precisely aligned using one or more fine alignment members 32. These fine alignment members 32 may be used in conjunction with the protruding members (e.g. guide posts 20) to help position and/or lock the components on the suction anchor foundation 2. The protruding members 20 may be used to guide the component (e.g. equipment support structure 29 and/or subsea equipment adapter frame 30) into approximately the correct location and orientation on the suction anchor 2 and the fine alignment members 32 may be used to precisely locate the components and lock them to the subsea installation 1. The fine alignment members 32 may be machined to a high tolerance to ensure that the components are located and/or locked in a precise location relative to the suction anchor 2 and/or wellhead 10. In other words, the guide posts 20 may be used as a coarse guiding means and the fine alignment members 32 may be used as a fine guiding/aligning means.

[0172] FIG. 3 shows a subsea well assembly 1 that comprises two suction anchors 2. The assembly comprises one equipment support structure 29 that extends over both suction anchors 2 and one subsea equipment adapter frame 30 that is supported by both suction anchors 2. Other than the fact that the arrangement comprises two suction anchors 2 rather than one, the assembly is otherwise equivalent to the examples shown in FIGS. 1 and 2.

[0173] In the assemblies of FIGS. 2 and 3, the wellhead supports cannot be seen as they are located in the internal volume of the suction anchor 1 rather than external to the internal volume on the top plate as in FIG. 1. FIG. 4 shows another subsea well assembly 1. This is broadly equivalent to the assembly 1 shown in FIG. 1 except the well support members 22 are not connected by an outer frame. Also the connection points 12 are mounted on/fixed to/part of the well support members 22. In this figure the connection points 16 are being shown as being used as lift points during installation or uninstallation of the assembly 1. The connection points 12 may be connected to other components such as wellhead load relief during other phases of operation.

[0174] FIGS. 5, 6 and 7 show assemblies 1′ that are equivalent to the assemblies shown in FIGS. 4, 2, 3 respectively, except that the foundation 2′ is not a suction anchor 2. In these assemblies 1′, the foundation 2′ is a plate or slab for example that may be fixed to the seabed by some other means such as cement. As the outer suction skirt 4 of the suction anchor 2 is no longer present, the central tube of the assembly can be seen.

[0175] FIG. 8 shows a subsea well assembly 1 that comprises two suction anchors 2. The two suction anchors 2 have different sizes. The subsea well assembly 1 comprises: (i) a first equipment support structure 29 that extends over a first suction anchor 2 and a first subsea equipment adapter frame 30 that is supported by the first suction anchor 2; and (ii) a second equipment support structure 29 that extends over a second suction anchor 2 and a second subsea equipment adapter frame 30 that is supported by the second suction anchor 2. The connection point 16 of the second suction anchor 2, for example, may be designed to have an adjustable height, i.e. adjustable length. This may be for example achieved by means of one or more adjustable inserts 13. The height of the connection points may be independently adjustable. Independent height adjustment features on individual connection points may permit component position and/or inclination to be adjusted. Other than the fact that the arrangement comprises two differently sized suction anchors 2 wherein the second suction anchor 2 includes adjustable inserts 13, the assembly is otherwise equivalent to the example shown in FIG. 2.

[0176] The following clauses set out features of the invention which may not presently be claimed but which may form the basis for amendments or future divisional applications.