NO20170948A1

NO20170948A1 - System and method for reducing fatigue on a well structure

Info

Publication number: NO20170948A1
Application number: NO20170948A
Authority: NO
Inventors: Gøran Olof Sundqvist; Harald Thomander Neerland; Per Torulf Hagner; Espen Berg; Ole Fjæstad
Original assignee: Fmc Kongsberg Subsea As
Priority date: 2017-06-12
Filing date: 2017-06-12
Publication date: 2018-12-13
Also published as: NO343847B1

Description

The invention relates to a system and method for reducing fatigue on a well structure, such as a wellhead or other well structures where fatigue may be an issue.

Background of the invention

Shallow water and deepwater rigs, drillships and intervention vessels can operate in different water depths ranging from tens of meters up to 4000 meters, or even more, deep. The wellhead and conductor system is the key load-bearing structure that supports the BOP and the various casings that collectively link the hydrocarbon reserve to the drilling rig or vessel. To avoid critical failures, it must ensure stability and structural integrity of the well for the duration of drilling operations or any other well operations where loads can be a critical factor.

Fatigue is a known problem in relation to subsea components. Fatigue occurs over time due to cyclic movements experienced by the components at risk.

Reference is made to document WO 2009102220 A2 which describes the technical field of the present invention, and the challenges with regards to fatigue and tear on subsea components, e.g. at a subsea wellhead. During subsea hydrocarbon extraction, a riser is utilized to establish a conduit between a floating vessel and a subsea wellhead. Due to that the riser in one end is connected to the structure on the seabed and at the other end to a vessel that is under the influence of wind and waves, the riser is experiencing stresses as the vessel moves. The riser is held in tension from the vessel and this will result in bending stresses in the riser as the vessel moves. To minimize these bending stresses, the riser is equipped with a flex joint and or possibly a bend restrictor at the wellhead. A bend restrictor will resist bending and avoid point stresses at the connector, but will not reduce the bending moment as such. An example of a flex joint as used in the industry is shown in US 5951061. Such a joint is designed with a certain stiffness to resist bending and, when bending occurs, to force realignment of the riser back to a neutral position.

A constant bending stress in itself will normally not damage the wellhead (or any other weak connection points in the riser) since the connector and the wellhead is designed to withstand these forces. However, the bending may be cyclic, due to vessel movements, and these cycles may result in fatigue problems at the wellhead.

The riser has a neutral position, i.e. a position where the bending moments acting on the riser are low (close to zero). However, due to movements caused by, wind, waves, tension, etc. the riser may move out of its neutral position, wherein some of this movement, at least the movement represented in angular displacement, is allowed by the flexible connection. When this occurs, the riser tends to react by creating a force in the opposite direction compared to the movement out of the neutral position. This opposite direction force is what creates a larger bending moment (and after time: fatigue) on the wellhead (or any other connection/riser part) the most. Thus, to reduce the bending moment, the applicant has solved this issue by, instead of seeking to counteract the movement out of neutral position, rather to apply an additional force which is equal to (or somewhat smaller) than the angular displacement force. The result being that the bending moments experienced at the wellhead is significantly reduced. However, when the forces on the flexible connection acts in another direction, the applied additional force is reduced/shutoff, and the riser is free to move in any direction. Thus, if the riser moves in another direction out of the neutral position than the direction explained above, an additional force may be applied in that direction instead. And, because the riser is moving cyclic, the process is repeated continuously.

Typically, the weakest point in the wellhead, and thus the design parameter, is the so-called H4 wellhead profile and the 36”x2” conductor extension girth weld (CEGW) which connects the conductor housing with the conductor extension. These two interfaces, i.e. the CEGW and the H4 wellhead profile, are used by all operators within the oil and gas industry and are thus normal design parameters which needs to be accounted for. They may thus be seen as industry standards.

In addition, in the prior art solutions, the wellhead has a tendency of being cemented inclined in the conductor housing in the permanent guide base.

Thus, an objective of the present invention is to overcome at least some of the drawbacks associated with the prior art solutions.

Another objective is to provide a system which improves the fatigue properties.

More specific, an objective of the invention is to route the forces experienced by the subsea component, e.g. wellhead, to other parts of the subsea structure, thereby increase the lifetime of the wellhead.

Summary of the invention

The invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention.

The present invention provides significant improvements in relation to known solutions.

An important improvement between the prior art solutions and the new solution, is that in the prior art solutions, the load distribution into the well template structed does not occur until the conductor housing is considerably bent or tilted towards the permanent guide base, and the load distribution changes dependent on the direction and magnitude of the load (i.e. a classical fatigue scenario). According to the design in the present invention, however, the load is constant into the well template structure from the beginning. Consequently, the fatigue loads are guided away from the wellhead system and into the well template structure. This results in, according to prior art designs, the load distribution being calculated based on that a major part of the load is taken by the wellhead. According to the present invention, however, calculation of the load distribution is based on that a majority of the loads are taken by the well template structure.

The system according to the invention routes the cyclic motions, i.e. the potential fatigue forces, to the well template structure instead of the wellhead.

Unexpectedly, tests have shown that the new solution gives additional effects in relation to a better tolerance loop between the wellhead and the well template structure/manifold. The connection between the wellhead and the flowline (in an on-template solution) is governed by several elements:

● Fabrication tolerances in the structures

● Functional clearances

● Tubing hanger orientation

● Well angle

These elements constitute a tolerance loop of which the well angle by far is the largest contributor. i.e. an improved well angle gives a reduced requirement for flexibility in the connections.

According to the present invention, it is provided a system for alignment of a conductor housing and creating a first contact point between an outer surface of a conductor housing and a well template structure, the conductor housing is configured to be installed within a hollow section of a wellbay in the well template structure, the hollow section comprising a first fixed support arrangement on an inner surface thereof and at least one movably arranged first pushing member, wherein the first pushing member is arranged to exert a radial force on the conductor housing when the conductor housing is arranged inside the hollow section, which force is configured to be applied in a direction towards the first fixed support arrangement such as to align at least a portion of the conductor housing substantially parallel with a center axis of the hollow section as well as to create at least a first contact point for distributing loads between the conductor housing and the well template structure. A majority of the loads are then transferred from the wellhead via the at least first contact point to the well template structure.

In an aspect, the system may comprise a second fixed support arrangement and at least a second pushing member, wherein the second pushing member is arranged to exert a radial force on the conductor housing when the conductor housing is arranged inside the hollow section in a direction towards the second fixed support arrangement.

According to an aspect, the first pushing member and the first fixed support arrangement and the second pushing member and the second fixed support arrangement are a force couple. Thus, if using an upper and lower system, i.e. two sets of system with centralizers and pushing members at different elevations along the conductor housing, the aligning operation is a force couple. A force couple is two parallel forces that are equal in magnitude, opposite in sense and do not share a line of action. It does not produce any translation, only rotation. The resultant force of a couple is zero. But, the resultant of a couple is not zero; it is a pure moment. For example, the forces that two hands apply to turn a steering wheel are often a couple. Each hand grips the wheel at points on opposite sides of the shaft. When they apply a force that is equal in magnitude yet opposite in direction the wheel rotates. If both hands applied a force in the same direction, the sum of the moments created by each force would equal zero and the wheel would not rotate. Instead of rotating around the shaft, the shaft would be loaded with a force tending to cause a translation with a magnitude of twice F. If the forces applied by the two hands were unequal, there would again be an unbalanced force creating a translation of the "system." A pure couple always consists of two forces equal in magnitude.

The moment of a couple is the product of the magnitude of one of the forces and the perpendicular distance between their lines of action: M = F x d.

According to an aspect, when the conductor housing is arranged inside the hollow section, the first fixed support arrangement of the hollow section and the first pushing member are centered around the conductor housing providing a 360 degree centering of the conductor housing within the hollow section of the wellbay.

According to an aspect, an inner surface of the first fixed support arrangement and the at least first and/or second pushing members form part of a full circle.

In contrast to permanent guide bases used in the prior art until today for guiding the conductor housing into place, the wellbay has additional features in addition to guiding features, including, but not limited to: an alignment function for aligning the conductor housing within a hollow section of the wellbay, and the possibility of creating a contact point between the outer surface of the conductor housing and the well template structure (via interface provided in the wellbay). Thus, when loads are applied to a wellhead above or inside the conductor housing, the features of the wellbay assists in a more favorable distribution of the applied loads (bending) exerted on the conductor housing into the well template structure rather than downwardly into the well.

The system may further comprise a hydraulic arrangement comprising an actuation cylinder and a locking arrangement, wherein the actuation cylinder may be retrievable after actuation of the first and second pushing members (e.g. locking dogs). Alternatively, the actuation may be performed using mechanical screws or bolts, driven hydraulically or electrically or by ROV, where tightening of the screw or bolt pushes the first (and possible additional) pushing member(s) into contact with the conductor housing creating the at least first contact point. The hydraulic arrangement may be remotely operated or have an interface which may be operated using a remotely operated device, such as a ROV (Remotely operated vehicle) or an AUV (Autonomous underwater vehicle).

The locking arrangement may be configured to lock the at least first and/or second wedges in the position where the locking dog(s) are pushing against the conductor housing and lock the locking dogs in position against the conductor housing. An alternative way of locking, either as a substitute or as an addition to the locking arrangement, may be performed by operating a secondary locking device which prevents that the first and second pushing members move relative each other after actuation, i.e. the distance between the first and second pushing members are fixedly secured by the secondary locking device. The secondary locking device may have different shapes and functioning mechanisms as long as it provides for a fixed locking of the first and second pushing members relative each other. For example, it may be formed of a rod, chains, cylinders etc, which may be remotely operated or by ROV.

In an aspect, the actuation cylinder may be arranged between the at first pushing member and the second pushing member and is configured to actuate both the first pushing member and the second pushing member. This actuation may preferably be simultaneous of the first and second pushing members.

The different support arrangements (i.e. the first, second, third, fourth, fifth, sixth support arrangement) may be provided at different positions along the longitudinal axis of the hollow section than the pushing member(s). For example, a first support arrangement may be at a first position, whereas a first pushing member may be at a second position different from the first position along the longitudinal axis of the hollow section, and a second support arrangement may be at a third position different from the first and second positions along the longitudinal axis of the hollow section. Preferably, if the system comprises a first support arrangement, a second support arrangement and a first pushing member, the pushing member is preferably arranged between the first support arrangement and the second support arrangement.

The invention further relates to a method of alignment of a conductor housing and creating a contact point between a conductor housing and a well template structure around an outer circumference of the conductor housing, the conductor housing is configured to be installed within a hollow section of a wellbay in the well template structure and the hollow section of the wellbay comprises a first fixed support arrangement on an inner surface thereof and at least one movably arranged first pushing member, wherein the method comprises the steps of:

a) drilling a hole corresponding to a diameter of a tailpipe in an underground formation,

b) drilling a hole with a smaller diameter from a lower end of the tailpipe, c) installing a conductor housing within the hollow section of the wellbay and in the hole with a smaller diameter,

d) operating the first pushing member in a direction towards the first support arrangement to align and center at least a portion of the conductor housing substantially parallel with a center axis of the hollow section and create at least one contact point extending around at least a portion of the outer circumference of the conductor housing.

The tailpipe is normally formed as part of the well template structure and is installed together with the well template structure. The function of the tailpipe is preventing wash-out during drilling operations. The hole drilled under step a) may thus be a 42” top hole drilled through the tailpipe.

It may further be arranged second pushing member and a second support arrangement at another position along a longitudinal axis of the hollow section, wherein the method further comprises, in relation to step d), operating the second pushing member in a direction towards the second support arrangement to form a force couple acting on the conductor housing, thereby aligning and centering at least a portion of the conductor housing substantially parallel with a center axis of the hollow section and create a first and second contact point extending around at least a portion of the outer circumference of the conductor housing.

The first, second and possible additional support arrangements and the first, second and possible additional pushing member(s), for example locking dogs, assist in centralizing and aligning the conductor housing supporting the wellhead, such that the wellhead can be cemented substantially vertical.

The present invention thus, for example, transfer BOP loads away from the wellhead system and into the well template structure or manifold.

Although the invention is described in relation to the system it is clear that the features described in relation to the system are relevant for the method according to the invention as well.

These and other characteristics of the invention will be clear from the following description of a preferential form of embodiment, given as a non-restrictive example, with reference to the attached drawings wherein:

Brief description of the drawings

Fig. 1 (prior art) shows an example of load distribution using a conventional wellbay having the features of a permanent guide base;

Figs. 2A and 2B are other examples of a prior art solution having a plurality of similar features as the solution disclosed in Figure 1, and Fig.2B is an enlarged view of detail ‘A’ on Fig. 2A;

Fig. 3A is an overview of the present invention;

Fig. 3B is an enlarged view of detail ‘B’ on Fig.3A;

Fig. 4 shows an example of load distribution, indicated by arrows, of a conductor housing installed in a system according to the invention;

Figs. 5A-5D are simplified sketches with examples of positions for a first, second and third fixed support arrangements and first, second and third pushing members along a longitudinal axis of a hollow section in a wellbay, seen from the side;

Figs. 6A-6E are examples of different possible cross sections providing a centralizing effect of the conductor housing within the hollow section of the wellbay, seen from above;

Fig 7A shows the conductor housing installed but with the pushing members in an inactive, retracted position;

Fig. 7B shows the conductor housing installed with the pushing members actuated towards the conductor housing;

Detailed description of a preferred embodiment

Although the drawings are described with focus on the system, and the components forming part of the system in accordance with the present invention, it is clear that the features described in relation to the system are relevant for the method according to the invention as well.

Fig. 1 (prior art) shows an example of load distribution using a conventional wellbay having the features of a permanent guide base. The conventional prior art setup in Fig. 1 typically calculates the loads based on a 50/50 load split between the wellhead system 3 and the well template structure 1. Typically, the weakest point in the wellhead, and thus the design parameter, is the so-called H4 wellhead profile and the 36”x2” conductor extension girth weld (CEGW) which connects the conductor housing with the conductor extension. A rigid lock seal assembly 4 locks the wellhead 3 to the conductor housing 2. The lock ring sleeve 5 locks around the conductor housing 2 and the template mounted guide base interface 6. The lock ring sleeve 5 is fixedly connected to the well template structure 1 in a fixation point 7 and seals around a groove 8 in the conductor housing 2. A permanent guide base structure 15 is fixed to the well template structure 1 and functions as a guide for the conductor housing 2 and conductor extension 2’. The template mounted guide base interface 6, in cooperation with the lock ring sleeve 5 render possible axial movement of the wellhead 3 and wellhead extension 3’ relative the well template structure 1 resulting from well growth height H (temperature variations in the well/well fluids/injection fluids/production fluids etc.). An inner bore 14 extends downwardly inside the conductor housing 2 and conductor extension 2’ and or the wellhead 3. The wellhead datum WHD is shown at the top of Figure 1.

As indicated by the size of the arrows denoted LDWHS (load distribution wellhead structure) compared to the arrows denoted LDWTS (load distribution well template structure) a significant amount of the forces on the wellhead 3 is directed downwardly into the conductor housing 2, conductor housing extension 2’ and thus to the conductor extension girth weld, CEGW. The load distribution into the well template structure 1 does not occur until the conductor housing 2 is considerably bent or tilted towards the permanent guide base structure 15, and the load distribution changes dependent on the direction and magnitude of the load. This results in, according to the design in Figure 1, that the load distribution is calculated based on a major part of the load is taken by the wellhead system LDWHS.

Fig. 2A and 2B are other examples of a prior art solution having a plurality of similar features as the solution disclosed in Figure 1. Figure 2B is an enlarged view of Detail ‘A’ on Figure 2A. Contrary to the solution in Figure 1, the prior art solution disclosed in Figure 2A has a fixed centralizer 10 mounted inside the permanent guide base structure 15 or on an outside of the conductor housing 2 for guiding a lower part of the conductor housing 2 in the permanent guide base structure 15. Two guide posts 13 are arranged at an upper part of the well template structure 1 to assist in guiding of equipment onto the well template structure or down into the well, e.g. through the inner bore 14. Figure 2B shows a similar connection between the wellhead 3, conductor housing 2 and permanent guide base structure 15 as described in relation to Figure 1, but with a lock ring 11 between the lock ring sleeve 5 and the conductor housing 2 and the template mounted guide base interface 6.

Fig. 3A is an overview of the present invention. Fig. 3B is an enlarged view of Detail ‘B’ on Figure 3A. It is shown a system, and the different components used in the method, according to the invention for alignment of a conductor housing 2 and creating a contact point 16’, 16’’ between an outer surface of a conductor housing 2 and a well template structure 1. The conductor housing 2 is installed within a hollow section 20 of a wellbay 100 in the well template structure 1. The hollow section 20 comprises a first fixed support arrangement 18’ on an inner surface thereof and at least one movably arranged first pushing member 19’. The first pushing member 19’ is arranged to exert a radial force on the conductor housing 2 when the conductor housing 2 is arranged inside the hollow section 20 in a direction towards the first fixed support arrangement 18’. This will align at least a portion of the conductor housing 2 substantially parallel with a center axis C of the hollow section 20 as well as it will create a first contact point 16’ for distributing loads between the conductor housing 2 and the well template structure 1. It is further disclosed a second fixed support arrangement 18’’ at another position along the longitudinal axis of the hollow section 20 and at least a second pushing member 19’’. The second pushing member 19’’ is arranged to exert a radial force on the conductor housing 2 when the conductor housing 2 is arranged inside the hollow section 20 in a direction towards the second fixed support arrangement 18’’. This particular setup, i.e. with the first pushing member 19’ cooperating with the first fixed support arrangement 18’ and the second pushing member 19’’ cooperating with the second fixed support arrangement 18’’, is a force couple.

An inner surface of the first and/or second fixed support arrangements 18’, 18’’ and the first and/or second pushing members 19’, 19’’ forms part of a full circle, thereby providing a 360 degrees alignment of the conductor housing 2 at the first and second contact points 16’, 16’’.

The first and/or second pushing member 19’, 19’’ are disclosed as locking dogs 19’, 19’’ which are actuated by movement of at least a first and/or second wedge 21’, 21’’. The wedges 21’, 21’’ are shaped such that upon movement of the first and/or second wedge 21’, 21’’, the wedge pushes the locking dogs 19’, 19’’ in a direction perpendicular to the movement of the wedge 21’, 21’’, i.e. if the wedge 21’, 21’’ moves vertically, the locking dog 19’, 19’’ is configured to be pushed horizontally, i.e. radially towards the conductor housing 2 in the Figures, into contact with the conductor housing 2. In the disclosed embodiment on Figure 3B, the actuation cylinder 22 is arranged between the first and second wedges 21’, 21’’, and hence the first and second pushing members 19’, 19’’, and if the actuation cylinder 22 is actuated, it pushes both upwardly against the first wedge 21’ and downwardly against the second wedge 21’’, simultaneously. This results in that the first and second locking dogs 19’, 19’’ are pushed simultaneously towards, and finally against, the conductor housing 2, thereby functioning as a force couple both aligning the conductor housing 2 substantially parallel with the hollow section 20 and creating the first and second contact points 16’, 16’’ for distribution of load forces.

The system may further comprise a hydraulic arrangement comprising an actuation cylinder 22 and a locking arrangement 23’, 23’’, wherein the actuation cylinder 22 may be retrievable after actuation of the first and second pushing members/locking dogs 19’, 19’’. The hydraulic arrangement may have an interface 17 which may be operated using a remotely operated device, such as a ROV (Remotely operated vehicle) or an AUV (Autonomous underwater vehicle). The locking arrangement 23’, 23’’ is configured to lock the at least first and/or second wedges 21’, 21’’ in the position where the locking dog(s) 19’, 19’ are pushing against the conductor housing 20 and lock the locking dogs 19’, 19’’ in position against the conductor housing 2. The locking arrangement may be parallel with or extend in the same longitudinal direction as the first or second pushing member or the locking arrangement may be inclined relative the longitudinal direction of the first or second pushing member. The locking arrangement may be a combination of parallel/same longitudinal direction and inclined, or, all may be parallel/same longitudinal direction, or all may be inclined.

Additional locking or alternative locking may be achieved by operating a secondary locking device 24 which prevents that the first and second pushing members 19’, 19’’ move relative each other after actuation, i.e. the distance between the first and second pushing members 19’, 19’’ are fixedly secured by the secondary locking device 24. The secondary locking device 24 may have different shapes and functioning mechanisms as long as it provides for a fixed locking of the first and second pushing members 19’, 19’’ relative each other.

The first and second wedges 21’, 21’’ are disclosed connected to the same actuation cylinder 22. However, they may be independently operated with one actuation cylinder 22 each (not shown).

Further, referring to Figs. 3A and 3B, a method according to the present invention may be described, i.e. a method of alignment of a conductor housing 20 and creating a contact point 16’, 16’’ between the conductor housing 2 and a well template structure 1 around an outer circumference of the conductor housing 2, the conductor housing 2 is configured to be installed within a hollow section 20 of a wellbay 100 in the well template structure 1 and the hollow section 20 of the wellbay 100 comprises a first fixed support arrangement 18’ on an inner surface thereof and at least one movably arranged first pushing member 19’, wherein the method comprises the steps of:

a) drilling a hole corresponding to a diameter of a tailpipe 12 in an underground formation,

b) drilling a hole with a smaller diameter from a lower end of the tailpipe 12, c) installing a conductor housing 2 within the hollow section 20 of the wellbay 100 and in the hole with a smaller diameter,

d) operating the first pushing member 19’ in a direction towards the first support arrangement 18’ to align and center at least a portion of the conductor housing 2 substantially parallel with a center axis C of the hollow section 20 and create at least one contact point 16’, 16’’ extending around at least a portion of the outer circumference of the conductor housing 2.

It may further be arranged second pushing member 19’’ and a second fixed support arrangement 18’’ at another position along a longitudinal axis of the hollow section 20, wherein the method further comprises, in relation to step d), operating the second pushing member 19’’ in a direction towards the second support arrangement 18’’ to form a force couple acting on the conductor housing 2, thereby aligning and centering at least a portion of the conductor housing 2 substantially parallel with a center axis C of the hollow section 20 and create a first and second contact point 16’, 16’’ extending around at least a portion of the outer circumference of the conductor housing 2.

Fig. 4 shows an example of load distribution, indicated by arrows, of a conductor housing 2 installed in a system according to the invention. As mentioned earlier, an important difference between the prior art solutions and the solution according to the present invention, is that according to the present invention, the load is constant into the well template structure from the beginning, i.e. from the time of the creating of the first contact point. Consequently, a significant amount of the fatigue loads are routed away from the wellhead system LDWHS and into the well template structure LDWTS instead. When comparing the load distributions (direction of arrows LDWTS and LDWHS) on Figures 1 and 4, it is clear that a much larger part of the loads are routed to LDWHS in Fig. 1 than in Fig. 4, thus resulting in fatigue on the weakest constructional part of the system, i.e. typically the conductor extension girth weld CEGW or the H4 wellhead profile.

Figs. 5A-5D are simplified sketches with examples of positions for a first, second and third fixed support arrangements 18’, 18’’, 18’’’ and first, second and third pushing members 19’, 19’’, 19’’’ along a longitudinal axis of a hollow section 20 in a wellbay 100, seen from the side. It is clear that the embodiments in Figures 5A-5D are for illustration purposes of possible positions for the first, second and third fixed support arrangements and first, second and third pushing members only, and that the systems disclosed in Figures 5A-5D may have all the features described in relation to the Figures 1-4 above.

In Fig. 5A, it is disclosed a first pushing member 19’ and a first support arrangement 118’ arranged at the same elevation.

In Fig. 5B it is disclosed a first pushing member 19’ and a first support arrangement 118’ arranged at a first position, as well as a second pushing member 19’’ and a second support arrangement 18’’ at a second position along a longitudinal axis of the hollow section 20.

In Fig. 5C it is disclosed a first pushing member 19’ and a first support arrangement 118’ arranged at a first position, as well as a second pushing member 19’’ and a second support arrangement 18’’ at a second position, as well as a third pushing member 19’’’ and a third support arrangement 18’’’at third position, along a longitudinal axis of the hollow section 20.

In Fig. 5D it is disclosed a first support arrangement 18’ at a first position, a first pushing member 19’ at a second position, and a second support arrangement at a third position, along a longitudinal axis of the hollow section 20. I.e. in the example in Fig. 5D the first pushing member 19’ and the first and second support arrangement 18’, 18’’ are not at the same position along the longitudinal axis of the hollow section 20, but this example will also provide for alignment of the conductor housing 2 within the hollow section of the wellbay 100.

Figs. 6A-6E are examples of different possible cross sections providing a centralizing effect of the conductor housing 2 within the hollow section 20 of the wellbay 100, seen from above. I.e. the cooperation of the first, second or third fixed support arrangement 18’, 18’’, 18’’’ and the first, second or third pushing member 19’, 19’’, 19’’’ center the conductor housing 2 inside the hollow section 20 of the wellbay 100. It is clear that the embodiments in Figures 6A-6E are for illustration purposes of possible shapes and positions for the first, second and third fixed support arrangements 18’, 18’’, 18’’’ and first, second and third pushing members 19’, 19’’, 19’’’ only, and that the systems disclosed in Figures 6A-6E may have all the features described in relation to the Figures 1-5 above. In all embodiments in Figures 6A-6E, a 360 degree centering of the conductor housing 2 within the hollow section 20 of the wellbay 100 is achieved.

Fig. 6A shows the support arrangement 18’, 18’, 18’’ having an inner surface (to be in contact with the conductor housing 2) of circular shape adapted to the outer surface shape of the conductor housing 2.

Fig. 6B show the support arrangement 18’, 18’, 18’’ as two separate parts arranged at ~120 degrees distance from each other and from the pushing member 19’, 19’’, 19’’’ along an arc formed around the conductor housing 2.

Fig. 6C shows the support arrangement 18’, 18’, 18’’ having an inner surface (to be in contact with the conductor housing 2) with a circular shape extending around ~120 degrees of the outer surface of the conductor housing 2.

Fig. 6D is the same embodiment as in Fig.6C, but with two support arrangements arranged around the conductor housing, each with a circular shape extending around ~90 degrees of the outer surface of the conductor housing 2.

Fig. 6E shows the support arrangement 18’, 18’, 18’’ extending around substantially the whole circumference of the conductor housing 2.

Fig 7A shows the conductor housing 20 installed. The pushing members 19’, 19’’ are in an inactive, retracted position.

Fig. 7B shows the conductor housing 20 installed with the pushing members actuated towards the conductor housing creating the first and second contact points 16’, 16’’. When comparing Figures 7A and 7B, it is clear that the actuation cylinder 22 has been actuated (the piston has moved from a compressed position and stroked out of the cylinder housing) thereby pushing the first and second wedges 21’, 21’’ upwardly and downwardly, respectively. The first and second wedges 21’, 21’’ have then actuated the first and second pushing members 19’, 19’’, respectively. After the actuation of the first and second pushing members, the locking arrangement 23’, 23’’ have been actuated to lock the first and second pushing members 19’, 19’’ in actuated position against the conductor housing 20. The upper locking arrangement 23’ is parallel with or extends the same longitudinal axis as the first pushing member 19’ whereas the lower locking arrangement 23’’ is inclined relative the longitudinal axis of the second pushing member 19’’. The locking arrangement may be as disclosed or, both may be parallel, or both may be inclined. Other alternative ways of locking may also be provided as long as they provide for sufficient locking of the at least first and second pushing members 19’, 19’’.

With reference to Fig. 3, a typical sequence may be:

1) Install well template structure 1 subsea, the well template structure 1 comprises a wellbay 100 having a hollow section 20,

2) Drill 42’’ hole for conductor housing 2 through one of the wellbays and tailpipe 12 in the well template structure 1,

3) Install 30’’ conductor housing 2. The conductor housing 2 will most probably be installed inclined relative the hollow section 20 of the wellbay 100 in the well template structure 1 because it is difficult, or even impossible, to drill completely vertical holes.

4) Install actuation cylinder(s) 22 (e.g. the retrievable cylinders) in the system according to the present invention. The actuation cylinders 22 being hydraulically operated.

5) Operate first and second pushing member 19’, 19’’, e.g. locking dogs 19’, 19’’, to contact with conductor housing 2 outer diameter ( ~ 30’’ conductor housing outer diameter) until it is centrally arranged and substantially vertical (parallel with hollow section 20 in wellbay 100), thereby creating a first and second contact point 16’, 16’. Cement the conductor housing 2. 6) Install the wellhead 3 inside the conductor housing 2. Cement the wellhead 3. The wellhead 3 will then be oriented substantially vertically inside the conductor housing 2 because the conductor housing 2 is centrally aligned under point 7), and the majority of the forces acting on the wellhead 3 will be distributed to the well template structure 1, via the first and second contact points 16’ 16’’ instead of going further down into the well and probably result in fatigue issues at the conductor extension girth weld CEGW.

Thus, at least one of the objectives of the invention is achieved by the system and method as disclosed in the drawings.

In the preceding description, various aspects of the invention have been described with reference to illustrative embodiments. For purposes of explanation, systems and configurations were set forth in order to provide a thorough understanding of the system and its workings. However, this description is not intended to be construed in a limiting sense. For example, other actuation arrangements than the hydraulic actuation system may be used, such as any mechanical, electrical system which provides for similar control and activation. Various modifications and variations of the illustrative embodiments, as well as other embodiments of the system, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention as defined in the appended claims.

Reference list:

Claims

1. System for alignment of a conductor housing (2) and creating a contact point (16’, 16’’) between an outer surface of a conductor housing (2) and a well template structure (1), the conductor housing (2) is configured to be installed within a hollow section (20) of a wellbay (100) in the well template structure (1), the hollow section (20) comprising a first fixed support arrangement (18’) on an inner surface thereof and at least one movably arranged first pushing member (19’), wherein the first pushing member (19’) is arranged to exert a radial force on the conductor housing (2) when the conductor housing (2) is arranged inside the hollow section (20), which force is configured to be applied in a direction towards the first fixed support arrangement (18’) such as to align at least a portion of the conductor housing (2) substantially parallel with a center axis (C) of the hollow section (20) as well as to create at least a first contact point (16’) for distributing loads between the conductor housing (2) and the well template structure (1).

2. The system according to claim 1, wherein the system comprises a second fixed support arrangement (18’’) and at least a second pushing member (19’’), wherein the second pushing member (19’’) is arranged to exert a radial force on the conductor housing (2) when the conductor housing (2) is arranged inside the hollow section (20) in a direction towards the second fixed support arrangement (18’’).

3. The system according to claim 2, wherein the first pushing member (19’) and the first fixed support arrangement (18’) and the second pushing member (19’’) and the second fixed support arrangement (18’’) are a force couple.

4. The system according to claim 1 or 2, wherein the first fixed support arrangement (18’) in the hollow section (20) and the first pushing member (19’), when the conductor housing (2) is arranged inside the hollow section (20), are centered around the conductor housing (2) providing a 360 degree centering of the conductor housing (2) within the hollow section (20) of the wellbay (100).

5. The system according to any of the preceding claims 2-4, wherein an inner surface of the at least first and/or second fixed support arrangements (18’, 18’’) and the at least first and/or second pushing members (19’, 19’’) forms part of a full circle.

6. System according to any of the preceding claims 2-5, wherein the first and/or second pushing member (19’, 19’’) comprises a locking dog (19’, 19’’) which is actuated by movement of at least a first and/or second wedge (21’, 21’’), such that, upon movement of the first and/or second wedge (21’, 21’’), the locking dog (19’, 19’’) is configured to be pushed into contact with the conductor housing (2) and be locked in position against the conductor housing (2).

7. System according to claim 6, wherein system comprises a hydraulic arrangement comprising an actuation cylinder (22) and a locking arrangement (23’, 23’), wherein the actuation cylinder (22) operates the first and/or second wedge(s) (21’, 21’’) and thereby the locking dog(s) (19’, 19’’) and the locking arrangement is configured to lock the at least first and/or second locking dog(s) (19’, 19’) against the conductor housing (2).

8. System according to claim 7, wherein the actuation cylinder is arranged between the at least first pushing member (19’) and the second pushing member (19’’) and is configured to actuate both the first pushing member (19’) and the second pushing member (19’’).

9. Method of alignment of a conductor housing (20) and creating a contact point (16’, 16’’) between the conductor housing (2) and a well template structure (1) around an outer circumference of the conductor housing (2), the conductor housing (2) is configured to be installed within a hollow section (20) of a wellbay (100) in the well template structure (1) and the hollow section (20) of the wellbay (100) comprises a first fixed support arrangement (18’) on an inner surface thereof and at least one movably arranged first pushing member (19’), wherein the method comprises the steps of:

a) drilling a hole corresponding to a diameter of a tailpipe (12) in an underground formation,

b) drilling a hole with a smaller diameter from a lower end of the tailpipe (12), c) installing a conductor housing (2) within the hollow section (20) of the wellbay (100) and in the hole with a smaller diameter,

d) operating the first pushing member (19’) in a direction towards the first support arrangement (18’) to align and center at least a portion of the conductor housing (2) substantially parallel with a center axis (C) of the hollow section (20) and create at least one contact point (16’, 16’’) extending around at least a portion of the outer circumference of the conductor housing

10. Method according to claim 9, further comprising a second pushing member (19’’) and a second support arrangement (18’’) at another position along a longitudinal axis of the hollow section (20), wherein the method further comprises, in relation to step e), operating the second pushing member (19’’) in a direction towards the second support arrangement (18’’) to form a force couple acting on the conductor housing (2), thereby aligning and centering at least a portion of the conductor housing (2) substantially parallel with a center axis (C) of the hollow section (20) and create a first and second contact point (16’, 16’’) extending around at least a portion of the outer circumference of the conductor housing (2).