WELL STRUCTURE SUPPORT SYSTEMS, APPARATUS AND METHODS

Support Systems, Apparatus and Methods

Technical Field

Some described examples relate to support systems, apparatus and methods for use with well structures.

Background

Operational and abandonment procedures will be required at some time during the lifecycle of a typical oil and gas well. However, as assets tend to age, the integrity of components within the well, such as conductors, casings, cementing, etc., may be uncertain. For example, the effect of corrosion and/or abrasion over time may reduce the integrity of well structures such as casing, etc. If the integrity of casing, etc., has deteriorated significantly with time then any such operational or abandonment procedure may present significant challenges when aiming to avoid unwanted damage to the well, which could otherwise result in well collapse, ruptured flow lines, hydrocarbon release, etc. In some cases, the cost and risk of performing such procedures on aging assets could be significant, particularly during well abandonment. Further, the costs involved in any procedure can be significant if the time taken to perform that procedure cannot be minimised.

This background serves only to set a scene to allow a skilled reader to better appreciate the following description. Therefore, none of the above discussion should necessarily be taken as an acknowledgement that that discussion is part of the state of the art or is common general knowledge. Summary

There are described support systems, apparatus and methods for use with well structures, which may be used to reduce the cost and/or risk of performing procedures on aging assets, for example, prior to or during well abandonment.

In some examples, there is provided a support system for a well structure. That support system may comprise an actuation system, for example, for use with a support member. The system may further comprise a support member configured for complementary engagement with the actuation system. In some examples, the support member may comprise one or more riser sections.

The system may further comprise a cross-over section, which may be provided at a lower end of the support member, or indeed be configured to couple with the lower end of the support member.

That cross-over section may comprise a body portion together with a well structure portion, where the well structure portion may be configured to couple with a wellhead, tree arrangement, or the like. A bore of the cross-over section may change (e.g. transition, such as taper) from a first inner diameter at wellhead portion to a second inner diameter at the body portion. The first inner diameter may be greater than the second inner diameter.

The first inner diameter may be defined by a corresponding diameter of a wellhead, or the like. For example, the first diameter may be in the region of 7 1/16 inches. The second inner diameter may be in the region of 6 1/2 inches, or less (e.g. 6.375 inches). In some examples, the cross-over section may comprise a support member portion configured to couple with the support member. In such cases, the cross-over section may comprise a third inner diameter, provided at the support member portion. The bore of the cross-over section may change (e.g. transition, such as taper) from the second inner diameter at the body portion to the third inner diameter at the support member portion. The third inner diameter may be greater than the second inner diameter. The first and third inner diameters may be same size of inner diameter.

The well structure portion of the cross-over section may comprise a well structure flange, configured to assist with coupling the cross-over section to the wellhead, tree, or the like (e.g. by bolting). The body portion of the cross-over section may be recessed relative to the well structure flange, which may assist with access to flange bolts, or the like. The support member portion of the cross-over section may comprise a support member flange, configured to assist with coupling the cross-over section to the support member (e.g. bolting). The body portion of the cross-over section may be recessed relative to the support member flange, which may assist with access to flange bolts, or the like.

The support member may comprise one or more support segments. In similar words, the support member may be provided by a single support segment, or be comprised of multiple segments coupled to one another to form the overall support member section. In some examples, the support member may comprise additional components, such as a pump in tee, or the like. The support member may comprise a mating component or feature, specifically configured for complementary engagement with the actuation system. The mating components may comprise, or be in the form of, one or more protrusions (e.g. flanges), and/or recesses, which may extend radially outwards/inwards from/to the support member, and may be provided around some or all of the support member. The mating component may be mountable and removable from the support member, or may be fixed in place.

The support member may comprise a plurality of mating components. Each mating component may be configured for complementary engagement with the actuation system at different positions along on the support member. The mating components may be spaced along the support member at intervals, for example at regular intervals. The mating components may be spaced by 10 inches, or so, along the support member.

The actuation system may be configured for complementary engagement with mating components directly. Otherwise, the actuation system may be configured for engagement with mating components via an engagement plate. The actuation system may be configured for complementary engagement with the engagement plate, which in turn may be configured for engagement with one or more of the mating components of the support member. In some examples, the engagement plate may be configured in split-form. For example, the engagement plate may have multiple plate elements arranged, when assembled, to provide the engagement plate (e.g. in a c-plate configuration). The engagement plate may circumscribe the support member, when in use (e.g. fully or partially circumscribe the support member). The engagement plate may be configured to distribute a load from the mating components to the actuation system. The engagement plate may be configured to distribute a load uniformly to the actuation system.

In some examples, the engagement plate may comprise one or more locating elements, or the like, for positioning the plate relative to the actuation system. The locating element(s) may be considered to assist with securing the relative position of the engagement plate together with the actuation system. In other similar words, the locating element(s) may be configured to inhibit relative movement of the engagement plate and the actuation system. The location elements may comprise one or more protrusions and/or recesses for complementary mating with corresponding features of the actuation system.

The actuation system may be configured to act upon the engagement plate, so as to support the support member (e.g. support at least the weight of the support member.). The actuation system may comprise one or more actuators configured, in use, to raise and/or lower the support member, when the support member is mated, or indeed a particular mating component of the support member is mated, together with the actuation system. The engagement plate, when if use, may be configured to distribute load to the one or more actuators. The engagement plate, when positioned relative to the actuation system, may extend above the actuators.

The actuation system may be configured to act upon the mating component of the support member, so as to support the support member (e.g. support the weight of the support member, and cross-over section, etc.). The actuation system may comprise one or more actuators configured, in use, to raise and/or lower the support member, when the support member is mated together with the actuation system. The actuation system may comprise a plurality of actuators (e.g. four actuators, or multiples of four actuators), which may be configured to raise/lower a complementary mating component of the actitation system. The mating component of the actuation system may comprise, or be in the form of, a mating plate. The engagement plate may be configured, in use, to distribute load from the support member to each of the plurality of actuators.

The actuation system (e.g. mating component of the actuation system) may comprise an opening, such as a side opening, to permit the support member to be positioned within and/or removed from the actuation system. In other words, any opening may permit accurate positioning of the support member (e.g. relative to a well structure), and subsequent location of the actuation system and support member together, using the opening. Further, the opening may facilitate removal of the system.

The actuation system may comprise one or more stabilisers (e.g. telescopic stabilisers) configured to maintain orientation of the mating component during lifting/lowering. The actuation system may comprise one or more lock-out mechanisms configured to fix (e.g. by a user) the relative position of the mating component prior or subsequent to raising/lowering. Actuators of the actuation system may replaceable, for example, during lock-out of the system. The actuators may be provided by one or more hydraulic rams. The actuator may be provided within defined seats to assist with positioning before and after replacement. The actuation system may comprise one or more actuation modules, which may be considered to be scalable modules. The modules may be stackable (e.g. one on top of another) so as to provide different raising/lowering characteristics (e.g. different effective heights). In some examples, the actuation system may be configured as a tension table, e.g. a modular tension table. Spacing between mating components of the support member may be arranged based on the raising/lowering characteristics of the actuation system.

The support member of the system may be configured additionally to couple with equipment for use in intervention or drilling procedures. For example, the support member may be configured, at an upper region, to couple with a blowout preventer, lubricator, or the like. The support member may comprise a through bore. The through bore may be sized so as to permit passage of downhole apparatus, such as intervention and/or abandonment tools. The support member may comprise a riser section.

The support member may have a particular structural rating (e.g. pressure rating, such as 10k psi). The system may be configured for use with well structures having a lower structural rating (e.g. pressure rating, such as 5k psi). The structural rating of the well structure may be half, or less than half, of the structural rating of the support member.

The actuation system may be configured to lower the support member towards a well structure. The actuation system may be configured to land off the support member (e.g. the lower end, and optionally the cross-over section) on a well structure. In some examples, the actuation system may be configured to land off the support member section onto the cross-over section, if that cross-over section were to already be coupled to the well structure.

When landing the support member on the well structure, some or all of the weight of the support member may be held by the actuation system. In other similar words, the gravitational force of the support member may be applied fully or partially through the actuation system, such that only some or none of that force is experienced at the well structure. When coupled to a well structure, the actuation system may be configured to apply force to the support member (e.g. apply tension to the support member). Such force may, in turn, be applied to the well structure (e.g. associated casing, etc.) when the support member is in communication with the well structure (e.g. connected directly or indirectly to the well structure). The actuation system may be configured to apply sufficient force so as to lift a wellhead, or the like, at a platform deck (e.g. at the wellhead deck). In other similar words, the actuation system may be configured to apply sufficient force so as to displace the wellhead or indeed well structure from its present position. In some examples, such displacement may cause the wellhead to move relative to the platform, e.g. relatively lifting the wellhead/well structure with respect to the platform.

The system (e.g. the actuation system) may comprise as at least one channel, which may be consider to be an access channel(s). Such an access channel may be provided when the support member is being restrained or otherwise supported by the actuation system.

The access channel may be defined through the actuation system, and optionally the engagement plate. The access channel may be configured to permit lifting medium to be communicated therethrough (e.g. when the support member is being restrained by the actuation system). The access channel may be defined in the actuation system and/or engagement plate. The support system for a well structure may comprise lifting medium. The lifting medium may be configured to attachment with a well head. The lifting medium may be comprise a bridle, or the like, for attachment to a well head. The system may be for use at a production rig or platform. The system may be configured for use with well structure provided at a production rig, having well infrastructure (e.g. conductors) communicating to seabed, or the like.

There is also described a support system for a well structure comprising:

an actuation system for supporting a well structure;

a support member, configured for use with a well structure, and for complementary engagement with the actuation system; and

wherein the support member comprises a plurality of mating components, each mating component configured for complementary engagement with the actuation system at different positions along on the support member.

There is also described a support system for a well structure comprising

an actuation system for supporting a well structure;

a support member, configured for use with supporting a well structure, and for complementary engagement with the actuation system; and

wherein the actuation system is configured to engage with the support member in order to restrain the support member relative to the actuation system, and further wherein

the support system comprises as at least one access channel, through which lifting medium can be communicated, when the support member is restrained by the actuation system. There is also described a support system for a well structure comprising

an actuation system, for example, for use with a support member;

a support member section, such as a riser section, configured for complementary engagement with the actuation system, and

a cross-over section, configure for use at a lower end of the support member, and comprising a body portion and a well structure portion, the well structure portion configured to couple with a wellhead/tree arrangement, and wherein a bore of the cross-over section changes from a first diameter at the body portion to a second diameter at the well structure portion, the second diameter being greater than the first diameter.

In some examples, there is described a method of supporting a well structure.

Corrosion, fatigue and/or wear, etc. may be suspected or identified/measured at a well structure.

In such cases, any intervention/drilling operations may be considered. The support member and actuation system (as described above) may be arranged together (e.g. with the support member being positioned relative to a wellhead/tree arrangement or the like).

Mating components of the support member and actuation system may be interfaced, e.g. either directly or via an engagement plate. This may occur when the actuation system is in a raised configuration (or towards a raised configuration). In some examples, one particular mating component (from a plurality of mating components) of the support member may be selected for mating with the actuation system, directly or indirectly. The support member may be lowered towards the wellhead/tree arrangement, etc. using the actuation system. Some or all of the weight of the support member may be held by the actuation system. The cross-over section, if coupled to the support member, may be securely coupled to the wellhead/tree arrangement, etc. Similarly, the support member may be secured to the cross-over section (if already secured to the wellhead/tree arrangement). Subsequently, when coupled to a wellhead/tree arrangement, the actuation system may lift and apply tension to the support member, and in turn the well structure.

Additional equipment (e.g. lubricator, etc.) may be coupled at an upper region of the support member. In such cases, the actuation system may be locked in position (hydraulically and/or mechanically) thus preventing transmissions of forces to the well structure.

Optionally, when in a restrained (e.g. when in a raised position), lifting medium may be communicated or at least have been positioned through at least one access channel provided in the system. That lifting medium may include hoisting cables, or the like, and may be coupled with the well structure (e.g. at a lower platform deck). The lifting medium may be directly or indirectly coupled with the well structure. Subsequently, the method may comprise transferring the load of the well structure from the actuation system to a hoist, or the like (e.g. from which the lifting medium depends). The method may comprising initially coupling a lifting bridle to the well structure (e.g. for subsequent lifting). The lifting bridle may be provided at the cross-over section. The method may comprise, subsequent to transferring load, removing the system including the actuation system (e.g. using an opening, such as a side opening, of the actuation system). In such cases, the lifting medium may remain in situ. There is also described individually an actuation system and support member for use with the system.

In some examples, there is described use of any of the above described support systems, methods, etc., for supporting well structures.

In one examples, there is described a method of supporting a well structure.

The method may comprise associating a support system with a wellhead/tree arrangement of the well structure. The method may comprise coupling the support system, either directly or indirectly, to the wellhead/tree arrangement. Force may be applied to the wellhead/tree arrangement using the support system in order to support the well structure.

A particular mating component of a support member of the support system may be interfaced, e.g. initially interfaced, with an actuation system of the support system, e.g. and then the support member may be associated with the wellhead/tree arrangement of the well structure. The mating component interfaced may be selected from a plurality of mating components of the support member, e.g. depending on the position of the wellhead/tree arrangement.

The support member may be interfaced when the actuation system when the actuation system is in a raised configuration, and then lowered so as to be associated the support member with the wellhead/tree arrangement. The support system may further comprise a cross-over section. The cross-over section may be securely coupled to the wellhead/tree arrangement, for example, either prior to or subsequent to lowering of the support member.

The method may comprise subsequently performing well operations, when the well structure is being supported. Lifting medium may be communicated through at least one access channel provided in the system, and coupled to well structure. The method may comprises transferring the load of the well structure from the support system to a hoist using the lifting medium. The method may comprise, subsequent to transferring the load, removing the support system for positon and leaving the lifting medium in situ. In some examples, this may occur when the support system is coupled to the tree arrangement. In other words, the well structure is supported by the lifting medium when the tree remains at the well head.

Aspects of the inventions described may include one or more examples, embodiments or features in isolation or in various combinations whether or not specifically stated (including claimed) in that combination or in isolation. It will be appreciated that one or more embodiments/examples may be useful with assets and associated well structures, particular those on production platforms, etc., which may require subsequent operational and/or abandonment proceedings during the lifetime of such an asset. The above summary is intended to be merely exemplary and non-limiting. Brief Description of the Figures A description is now given, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 shows a simplified representation of a platform comprising a support system;

Figures 2a and 2b show simplified representations of the system of Figure 1 ; Figure 3a, 3b, and 3c shows examples of actuation systems; Figure 4 shows an example of a cross-over section;

Figures 5a-5d show examples of stages of operation of a system; Figure 6a and 6b show a further example of a support system; and

Figures 7a-7e shows examples of the support system of Figure 6a and 6b in use. Description of Specific Embodiments Some of the following examples are described specifically with reference to offshore production rigs or platforms, in which well structures (e.g. comprising surface wellhead, surface trees, etc.) typically are positioned at a wellhead deck (e.g. below the rig/drilling floor). Such rigs may comprise fixed steel jackets, or be concrete legged, or the like, having well structure (e.g. conductor tubing, casing, etc.) extending from around the region of the wellhead to a seabed, and potentially beyond. However, it will be appreciated that the same systems, apparatus and methods described herein may equally be used in other situations, particularly where subsequent operational or abandonment procedures may be desired and, for example, where there may be a desire to reduce the cost and risk of performing such procedures on aging assets (e.g. prior to or during well abandonment). Further, while in this example, reference is made be oil and gas production structures, it will be appreciated that the systems and methods disclosed may be used on different situations and industries.

Figure 1 shows a simplified representation of an offshore platform 10 together with support system 100, as will be described. Here, well structure 15 (e.g. conductor, casing, etc.) extends from a subsea well 20, below a mudline 30, to the platform 10 in order to communicate product from the well 20 to the platform 10. In this example, a wellhead or tree arrangement 50, or the like, is positioned at the platform 10 (i.e. surface or dry tree). In many instances, such platforms 10 comprise multiple decks, such as upper or drilling deck 5, lower or wellhead deck 6, and indeed cellar decks 7. Typically, such wellhead/tree arrangements 50 are seated or otherwise positioned at a wellhead deck 60. It will be appreciated that in many examples, each platform 10 may have multiple well structures 15 extending from the platform 10 to the mudline 30 below. However, for ease of explanation only, a single well structure 15 is essentially described here. That said, the system 100 may be used with multiple well structures. During operational and/or abandonment procedures, it may be helpful to support the well structure 15. For example, during such procedures, it may be desirable to shut in the well and/or for the well 20 to be plugged at a downhole location (e.g. using one or more barriers, such as a double barrier arrangement). In some cases, for example when the well 20 is being decommissioned, and some tubing, such as production tubing and casing, may be removed from the well structure 15. During years of service, however, some of the structure 15 (e.g. casing, conductor, etc.) extending particularly from the platform 10 to the mudline 30 may have become corroded, worn, or otherwise fatigued, etc. This may have occurred due to interaction with environment conditions, and/or years of production and service. Therefore, there may be some risk associated with operational or abandonment procedures at this time due. In some cases, some amount of uncertainty may be present due to the uncertain mechanical condition of the well structure 15. Further, any uncertainty around the condition of the well structure 15 may lead to excessive time and costs being incurring, when performing operations at the platform.

Figure 2a shows a simplified representation of one example of the support system 100 positioned at a platform 10 of Figure 1. A wellhead/tree arrangement 50 is shown at the lower deck 6, and is connecting to well structure 15 extending to the seabed and towards a hydrocarbon bearing formation 20, as described above. It will be appreciated that for the purposes of explanation, coupling to the wellhead/tree arrangement 50 may relate either to the wellhead itself, for example in the absence of a tree, or to the tree itself.

Here, the support system 100 is shown in more detail and comprises an actuation system 1 10 and a support member 120, as will be further described. In this particular example, a cross-over section 130 is also shown. Here, the cross-over section 130 is coupled or otherwise in communication with the support member 120. It will be appreciated that the support member 120 may comprises one or more segments or, in similar words, the support member 120 may be provided by a single segment, or be comprised of multiple segments coupled to one another to form the overall support member 120. In some examples, the support member 120 may comprise additional components, such as a pump in tee, or the like, as may be useful for the particular operational needs.

In this simplified example, however - and for ease of understanding - the support member 120 is essentially shown as a single segment. In any event, the support member 120 of the system 100 may, in some examples, be configured to couple with equipment 200 (shown in dashed lines) for use in intervention and/or abandonment procedures, or the like. Here, the support member 120 is configured, at an upper region, to couple with a lubricator stack, or the like. As will be further explained, the support member 120 may comprise or otherwise be configured from a section of riser (e.g. tubing comprising a through bore). Such tubing or riser section may be similar to that used in other subsea procedures, or the like.

The actuation system 110 shown in Figure 2a and 2b is positioned at the upper deck 5 and is specifically configured for use with the support member 120. In that regard, the support member 120 can be considered to be configured for complementary engagement with the actuation system 110.

Here, the support member 120 comprises a mating component 125, specifically configured for complementary engagement with the actuation system 110. The mating component 125 in this example comprises, or at least may be considered to be in the form of, a flange 125. Here, that flange extends radially outwards from the support member 120 around some or all of the support member 120 (e.g. comprising a pancake flange, or the like). In some examples, the mating component 125 is mountable and removable from the support member 120, while in others it may be fixed in place. The actuation system 1 10 shown is configured to act upon the mating component 125 of the support member 120, so as to support the support member 120 (e.g. support the weight of the support member 120, and optional cross-over section 130, etc.). In use, and as will be further described, the actuation system 1 10 comprises one or more actuators 112 - see Figure 3 - configured to raise and/or lower the support member 120, when the support member 120 is mated together with the actuation system 110 . Figure 2b shows the system 100, and in particular the support member 120, in a lowered configuration. In such a configuration, the support member 120 (and optional cross-over section 130) is positioned proximate the wellhead/tree arrangement 50, or the like.

Figures 3a, 3b and 3c show one example of the actuation system 1 10 in more detail. Figure 3a shows the actuation system 1 10 comprising two actuation modules 114a, 1 14b, which may be considered to be scalable modules. In other words, in some examples more or fewer modules 114a may be provided, depending on application. Figure 3b shows the actuation system 1 10 having only a single module 114. The modules 1 14 here may be considered to be stackable (e.g. one on top of another) so as to provide different raising/lowering characteristics (e.g. different effective heights). In both Figure 3a and 3b, the actuation system 110 may be considered to have a generally rectangular profile, when viewed from above (as perhaps is better shown in perspective view of Figure 3c). Here, each module 1 14 comprises four actuators positioned generally at the corner regions of the actuation system 1 10. Hydraulic rams may be used as actuators 1 12. In use, a hydraulic pump or the like may be used to energise the actuators 1 12 (e.g. rams) to a required/desired load. For completeness, the actuators 112 have been omitted in Figure 3c. Here, seats 115 within which the actuators 1 12 can be removably located are shown. It will be appreciated that the force being applied, or indeed the load being lifted, may be measured by monitoring the conditions at the actuation system (e.g. the force being applied by the actuators).

As is shown in Figure 3a, 3b and 3c, the actuation system 1 10 can be configured to raise/lower support member 120 using a complementary mating component 1 16 of the actuation system 1 10. Here, mating component 1 16 comprises, or at least may be considered to be in the form of, a mating plate 1 16, or otherwise engagement plate. In this example, that mating component of engagement plate may be considered to be integrally formed at an upper surface of the actuation system 1 10.

As shown best in Figure 3c, the actuation system 1 10 (e.g. including the mating component 1 16) comprises an opening 1 17, such as a side opening. Here, the opening 1 17 is configured to permit the support member 120 to be positioned within the actuation system 1 10. In other words, the opening 117 may permit relative positioning of the support member 120 and the actuation system 1 10, by introducing the support member at the side opening 1 17 of the actuation system 1 10. In such a way, either of the support member 120 or actuation system 1 10 may be moved and positioned relative to one another.

For example, the opening 117 may permit accurate positioning of the support member 120 (e.g. relative to a wellhead/tree arrangement 50), and subsequent location of the actuation system 1 10 and support member 120 together, using the opening 117.

In some examples, the opening 117 may be provided with a gate or the like. However, in this example, the force applied in use through the mating components 1 16/125 of the support member 120 and actuation system 110 is sufficient to retain the support member 120 with the actuation system 1 10. Here, this example of actuation system 110 further comprises one or more guides or stabilisers 118, which are exemplified as telescopic stabilisers 118 configured to assist in preventing or mitigating overextension of the actuators 1 12. Additionally or alternatively, the stabilisers 1 18 in some examples may be considered to maintain orientation of the mating component 1 16 during lifting/lowering.

The actuation system 110 may also comprise one or more lock-out mechanisms 119 configured to fix (e.g. by a user) the relative position of the mating component 116 subsequent to raising/lowering. In this example, the lock-out mechanisms 119 are provided at the stabilisers 118 by means of a pin arrangement.

Figure 4 shows in more detail an example of the cross-over section 130, which may be used with the support system 100. Here, the cross-over section 130 can be provided at a lower end of the support member 120 or indeed initially coupled to the wellhead/tree arrangement 50, or the like, for subsequent coupling to the support member 120. In this particular example, the cross-over section 130 is configured to be coupled towards (at the right hand side of Figure 3) the support member 120, and configured to be coupled towards (at the left hand side of Figure 3) the wellhead/tree arrangement 50, or the like. Ring grooves 150 for gaskets are shown. It will be appreciated that the cross-over section 130 may be coupled directly, or indeed indirectly via an intermediate joint or the like, with the support member 120 and wellhead/tree arrangement 50. In this example, however, the cross-over section 130 intends to be coupled directly to the wellhead/tree arrangement 50.

The cross-over section 130 comprises a body portion 132 together with a well structure portion 134, where the well structure portion 134 is configured to couple with the wellhead/tree arrangement 50. The cross-over section 130 further comprises a support member portion 136 configured to couple with the support member 120.

A bore 138 of the cross-over section changes (e.g. transitions, such as tapers) from a first inner diameter 144 at well structure portion 134 to a second inner diameter 142 at the body portion 132. The first inner diameter 144 is greater than the second inner diameter 142.

The cross-over section 130 comprises a third inner diameter 146, provided at the support member portion 136. The bore 138 of the cross-over section 130 again changes (e.g. transitions, such as tapers) from the second inner diameter 142 at body portion 132 to the third inner diameter 146 at the support member portion 136. The third inner diameter 146 is greater than the second inner diameter 142. In this example, the first and third inner diameters 142, 146 are the same diameter.

In the example shown, the first inner diameter 144 may be considered to be defined by the corresponding diameter at the well structure 50. For example, the first inner diameter may be in the region of 7 1/16 inches. Similarly, the third inner diameter may be considered to be defined by the corresponding diameter at the support member 120 (e.g. in the region of 7 1/16 inches). The second inner diameter 142 here is in the region of 6 1/2 inches, or less (e.g. 6.375 inches).

As is shown, the support member portion 136 comprises a flange 156, configured to assist with coupling the cross-over section 130 to the support member 120 (e.g. bolting). In this example, the support member 120 has a particular structural rating (e.g. pressure rating, such as 10k psi), which means that the flange 156 is greater than that at the other end of the cross-over section 130 - e.g. a well structure flange 154 (which may be configured for use with well structures have a lower structural rating (e.g. pressure rating, such as 5k psi)). The body portion 132 is recessed relative to the support member flange 156, which assists with access to flange bolts, or the like. By providing the cross-over section in this manner, riser sections or the like, which may have a greater pressure rating that the well structure 15 can be safely used.

Here, the well structure portion 134 comprises a wellhead/tree flange 154, configured to assist with coupling the cross-over section 130 to the wellhead/tree arrangement 50 (e.g. bolting). The body portion 132 is essentially recessed relative to the wellhead/tree flange 154. In such a way, access to bolts or the like is not inhibited. Further, due to the manner in which the cross-over section 130 is tapered to a narrower inner diameter, the structural strength of the cross-over section 130 at the recess is not unduly affected. Put differently, a secure seal can be maintained between the wellhead/tree arrangement 50 and cross-over section 130 by providing sufficient clearance for securing bolts, etc., while at the same time forces (e.g. tensile loads) can be appropriately passed through the cross-over section 130 without yielding. It will be appreciated that as tension is applied across the cross-over section, then any compression coupling (e.g. using bolts or the like) at the wellhead/tree structure 50 may be reduced, and unhelpfully compromised, which could result in unwanted leakage. By providing sufficient clearance at the recess of the cross-over section 130, larger headed bolts may, in some examples, be provided, thus further increasing compressive forces.

In use, when corrosion, fatigue and/or wear, etc. may be suspected or identified/measured at a well structure and in which any intervention/abandonment operations may be considered, then the system 100 may be used, by way of an example only, as follows. Initially, the support member 120 and actuation system 1 10 may be arranged together. In some examples, the support member 120 and cross-over section 130 are positioned relative to the wellhead/tree arrangement 50. As mentioned, in some cases, the cross- over section 130 may be initially coupled to the wellhead/tree arrangement 50.

Mating components 125, 116 of the support member 120 and actuation system 110 can interface together, while the actuation system 1 10 is in a raised configuration (e.g. similar to Figure 1 a). Subsequently, the support member 120, and optionally the cross- over section 130, can be lowered towards the wellhead/tree arrangement 50 using the actuation system 110.

In such a way, the actuation system 1 10 is configured to land off the support member 120/cross-over section 130 on a wellhead/tree 50. At the time of landing the support member 120/cross-over section 130 on the wellhead/tree 50, some or all of the weight of the support member 120 may be held by the actuation system 1 10 (e.g. passed through the upper deck 5). In other similar words, the gravitational force of the support member 120 may be applied full or partially through the actuation system 1 10, such that only some or none of that force is experienced at the wellhead/tree arrangement 50.

Due to its particular configuration, the cross-over section 130 can be securely coupled to the wellhead/tree arrangement 50. Subsequently, when coupled to a wellhead/tree arrangement 50, the actuation system 1 10 may be configured to apply force (e.g. tension) and lift the support member 120, and in turn the wellhead/tree arrangement 50 (e.g. and associated well structure 15, etc.). In such a way, the compressive forces at the well structure 15, or the like, can be reduced. At the same time, due to the construction of the cross-over section 130, the risk of leaks at the coupling or mechanical failure is reduced.

After the well structure 15 has been stabilised in this manner, additional equipment 200 (e.g. a lubricator stack, etc.) may be coupled at an upper region of the support member 120. In such cases, the actuation system 1 10 may be locked in position (hydraulically and/or mechanically) thus preventing transmissions of forces to the well.

Disconnection of the system 100 may occur in reverse order.

While in the above example, the additional equipment 200 may be fitted after coupling to the wellhead/tree arrangement 50, it will be appreciated that in other examples that need not be the case, and in fact the equipment 200 may be coupled to the support member 120 prior to coupling with the wellhead/tree arrangement 50. Further, described above the support member and cross-over section have been coupled initially, and then coupled to the wellhead/tree arrangement 50, it will nevertheless be appreciated that the cross-over section 130 may initially be coupled to the wellhead/tree arrangement 50, and then coupled to the support member 120 (e.g. after lowering the support member 120 to position). A skilled reader will readily be able to implement alternative embodiments.

Figure 5a shows an example of the wellhead/tree arrangement 50 being connected, via the cross-over section 130, to the support member 120. Figure 5b shows the well structure 15 being supported. Here, and as can be seen, the well structure 15 has been lifted from its previous position. Figure 5c shows the actuation system 110 having additional equipment 200 coupled to the upper end of the support member 120. Figure 5d shows subsequent disconnect of the support member 120 from the wellhead/tree arrangement 50 (or indeed the crossover section 130). Use of the above described system 100 may permit in the region of, of indeed in excess of, 400 Te, or indeed 500 Te, to be applied using the actuation system 1 10.

While in the above example, the support member 120 was described in relation to using a single mating component 125, it will be appreciated that alternative support members 120 may be provided, with more than one mating component 125, e.g. a plurality of mating components.

Consider now Figure 6a which shows a further example of a support system 200, comprising an alternative support member 220 and actuation system 210 in which the support member 220 comprises a plurality of mating components 235. Figure 6b shows a section view through X-X in Figure 6a.

In this example, the actuation system 210 is largely the same as described above, and comprising actuators 212, side opening 217, etc. Also, again, the support member 220 comprises mating components 235 that comprise, or are in the form of, one or more protrusions (e.g. flanges). In this example, those mating components 235 extend radially outwards from the support member 220. Also here, those mating components 235 are provided around the support member 220, and are fixed in place. The plurality of mating components 235 are each configured for complementary engagement with the actuation system 210 at different positions along on the support member 220, as will be further described. In this particular example, the mating components 235 are spaced along the support member 220 at regular intervals, and typically spaced in the region of 25 cm (e.g. 10 inches), or so, apart along the support member 220.

Here, the actuation system 210 is configured for engagement with mating components via an intermediate engagement plate 237. In this example, the engagement plate 237 may be configured in split-form. For example, the engagement plate 237 described here has two plate elements 237a, 237b arranged, when assembled, to provide the engagement plate 237 (e.g. in a c-plate configuration). Of course, in other examples more than two plate elements 237a, 237b may be provided.

As is shown in Figure 6b, the engagement plate 237 is configured to circumscribe the support member 220, when in use. Also, the engagement plate 237 is configured to distribute a load from the mating components 235 to the actuation system 210, and in this example distribute a load uniformly to the actuation system 210.

Here, as is shown in Figure 6a, the support system 200, and in this example the engagement plate 237, comprises one or more locating elements 238, or the like, for positioning the plate 237 relative to the actuation system 210. The locating element(s) may be considered to assist with securing the relative position of the engagement plate 237 together with the actuation system 210. In other similar words, the locating element(s) 238 may be configured to inhibit relative movement of the engagement plate 237 and the actuation system 210. Although alternatives may be provided, in the example described the location elements 238 may comprise one or more protrusions and/or recesses for complementary mating with corresponding features of the actuation system 210. When selectively located with one of the mating components 235 of the support member 220, the actuation system 210 is configured to act upon the engagement plate 237, so as to support the support member 220 (e.g. support at least the weight of the support member 220). The engagement plate 237, when in use, can be configured to distribute load from the support member 220 to the actuators 212 of the actuation system 210. In the example shown, the engagement plate 237, when positioned relative to the actuation system 210, extends above the actuators 212.

Here, the system 200 further comprises as at least one channel 260, which may be consider to be an access channel 260 through the actuation system 210. The access channel 260 is defined through the actuation system 210, and in particular in this example through the optional engagement plate 237. In doing so, at least a portion of the access channel 260 is essentially formed when sections of engagement plate 237 are assembled together. In other words, an aperture forming some of the access channel 260 is defined in complementary notched, or cutaway sections of the engagement plate 237. The access channel 260 is configured to permit lifting medium 270 (see Figure 7d, etc.) to be communicated therethrough or otherwise around the support system 200 (e.g. when the support member 220 is being restrained by the actuation system 210). As can be seen in Figures 6a and 6b, the access channel 260 can be provided when the support member 220 is being restrained or otherwise supported by the actuation system 210.

If optional slips 280 are provided at any time during use of the system 200, then these can be removed or engineered so as to allow passage of lifting medium 270 through the slips280/deck 5 (e.g. in a similar manner to the engagement plate 237). In use, and as shown in Figures 7a-7e, when corrosion, fatigue and/or wear, etc. may be suspected or identified/measured at a well structure 15 and in which any intervention/abandonment operations may be considered, then the system 200 may be used, by way of an example only, as follows.

Initially, the support member 220 and actuation system 1 10 may be arranged together such that an appropriately selected mating component 235 of the support member 220 is used. The appropriate mating component 235 may be selected depending on the expected position of the wellhead/tree arrangement 50, relative to the actuation system 210/support member 220. Further, the selected mating component 235 may be used depending on the expected potential displacement of the actuation system 210. In such a way, the same support member 220 can be used in many different platform 10 environments, and/or with different modular configurations of actuation systems 210 (e.g. when using one or more modular components, stacked). As such, the time and costs associated with operations at the platform 10 can be minimised.

During positioning of the support member 220, the engagement plate 237 may be positioned around the support member 220, and an aperture forming part of the access channel 260 formed. Figure 7a shows the system 200 is a raised configuration. For ease, a cross-over section 130 is not shown in Figure 7a, although it will be appreciated that this may be used in the same manner as described above, e.g. coupled to the wellhead/tree arrangement 50 or the support member 220.

Subsequently to mating of the support member 220 and actuation system 210, the support member 220, and optionally the cross-over section 130, can be lowered towards the wellhead/tree arrangement 50 using the actuation system 210, as is shown in Figure 7b. In such a way, the actuation system 210 is configured to land off the support member 220 on a wellhead/tree arrangement 50. At the time of landing the support member 220 on the wellhead/tree arrangement 50, again some or all of the weight of the support member 220 may be held by the actuation system 210 (e.g. passed through the upper deck 5). In other similar words, the gravitational force of the support member 220 may be applied full or partially through the actuation system 210, such that only some or none of that force is experienced at the wellhead/tree 50.

Subsequently, when coupled to a wellhead/tree arrangement 50, the actuation system 210 can be configured to apply force (e.g. tension) to the support member 220, and in turn the wellhead/tree arrangement 50 (e.g. and associated well structure 15, etc.), as is shown in Figure 7c. In such a way, the well structure 15 can be stabilised.

In this example, when in a restrained state (e.g. when in a raised position), lifting medium 270 may be communicated, or previously positioned, through at least one access channel 260 provided in the system 200. That lifting medium 270 may include hoisting cables, or the like, and can be coupled to the well structure 15 (e.g. at a lower platform deck), as is shown in Figure 7d. Here, the lifting medium 270 is coupled to the wellhead/tree arrangement 50 via a bridle arrangement 275. Connection for the bridle arrangement may be provided with the cross-over section 130, if provided, or otherwise provided at the wellhead/tree arrangement 50.

Here, a hoist (not shown) may be used in order to transfer the load of the well structure 15 from the support system 200 to the lifting medium 260 (and so to the hoist). Subsequent to transferring the load, and due to the configuration of the system 200, and in particular the access channel 260 and side opening 1 17, the engagement plate 237 may be removed, together with the support member 220 and actuation system 210. As such, the well structure 15 can be fully supported by the hoist, as shown in Figure 7e. In such cases, the lifting medium 260 remains in situ. As such, the time and costs associated with operations at the platform 10 can be minimised.

It will be appreciated when considering Figures 5b and 7c, that the system 100, 200 can be configured to stabilise the well structure 15 prior to some procedure. In some examples, the system 100, 200 may be used to support or otherwise stabilise the well structure during intervention, or abandonment. However, the system 100, 200 may also be used to stabilise the well structure 15 during times when production is ceased.

It will be appreciate that while certain features have been described in relation to the system 200 of Figures 6 and 7, that these may equally be applied to the system of Figures 2-5, and vice versa.

The applicant discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.