Subsea assembly and associated methods

GB2642652A8Pending Publication Date: 2026-02-04AKER SOLUTIONS SUBSEA AS
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Patent Information

Application Number
GB2023017022
Authority / Receiving Office
GB · GB
Patent Type
Applications
Current Assignee / Owner
Filing Date
2023-11-06
Publication Date
2026-02-04

AI Technical Summary

Technical Problem

Existing subsea Christmas trees face challenges in safely supporting and protecting Remotely Operated Vehicles (ROVs) during operations, such as accidental damage to components and entanglement of electrical flying leads, while also requiring efficient electric actuation systems.

Method used

A subsea Christmas tree design featuring a horizontal roof with a protective cover and support members to safely land and support ROVs, along with electric actuators and a modular shelf system for enhanced accessibility and protection of components, including a Power and Communication Gateway Module accessible from the front.

Benefits of technology

Enhances ROV operations by preventing accidental damage and entanglement, improves accessibility of components, and facilitates efficient electric actuation, reducing material and operational costs.

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Abstract

A subsea vertical Xmas Tree (XT) for a wellhead comprising a roof for receiving and supporting a Remotely Operated Vehicle (ROV) capable of performing operations. The roof 22 of the XT 10 may have a c
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Description

This invention relates to a subsea assembly, such as a Christmas tree for controlling a flow of fluid from a completed oil or gas well. BACKGROUND In subsea applications, various types of infrastructure are deployed, often positioned along a sea floor. In the oil / gas industry, a Xmas Tree (“XT”) is mounted on top of the wellhead or a completed well for controlling the production flow out of the well. The flow of oil and / or gas from the well is generally controlled using various valves, spools and fittings of the XT. In addition, the XT has further functions, such as chemical injection ports for the injection of chemicals into the well, pressure relief valves, providing hydraulic functions in the well bore, and connections to well sensors (e.g. for monitoring pressure, temperature, flow rate, fluid composition etc.). The XT also provides valves which are operable to shut-in the well in the event of an emergency. For example, XTs typically have various fluid barriers for controlling fluid, pressure, flow in the well. Periodically XTs may require maintenance, inspection, etc. Often temporary barriers are placed using bores below the XT. These bores are typically dedicated for such temporary use and access via these bores is only enabled when particular valves are open to allow such access. The valves are typically gate valves operable between a closed position, where the bore (below the XMT) is closed. Such valves, to control or vary supply or flow of a fluid, are often controlled by actuators. For example, the gate valves are typically translated linearly between open and closed states using an actuator to push / pull the valve open and closed. The valves can be for controlling fluids, such as production, flow, shut-down, etc. Actuators are often used in such subsea equipment, for control, such as production control, supply, distribution, safety or other functions. Traditionally, most of the subsea production systems have used hydraulic fluids for actuators for operating the subsea valves; although electric actuation systems have been introduced. The valves / actuators often have a failsafe mode, such as with a spring to automatically move the valve (e.g. in emergency or fault situations). Sometimes, such as where a primary drive mechanism fails, or a control or supply system therefor, it can be necessary to override the valve or the actuator. For example, a diver or ROV can typically access a mechanical override, for moving the actuator / valve. It may be an object of one or more aspects, examples, embodiments, or claims of the present disclosure to at least mitigate or ameliorate one or more problems associated with the prior art, such as those described herein or elsewhere. BRIEF SUMMARY OF THE DISCLOSURE According to an aspect, there is provided a subsea Xmas Tree (“XT”). The XT may comprise a support structure, the support structure having a plurality of devices, modules or components mounted or mountable thereto or thereon. The support structure may comprise a support frame. The XT may comprise a horizontal roof that is configured to receive and support a ROV thereon. Accordingly, in at least some examples, there is provided a subsea Xmas Tree (“XT”) for a wellhead, the XT comprising a roof, wherein the roof is configured to receive and support a Remotely Operated Vehicle (ROV) thereon. The ROV may be for performing operations on the XT, such as operating connections, performing inspections, checking statuses, installing and / or removing components or connections. As such, the ROV may comprise a relatively substantial mass and volume (e.g. compared to other ROVs, not capable of performing such operations on XTs). The roof may comprise a protective cover in the form of a horizontal, planar panel. The cover may protect devices, modules or components housed thereunder. Furthermore, the cover may provide a landing or even a docking location for a ROV thereon. The roof additionally may comprise an open portion. The open portion may be devoid of the cover panel, effectively being formed by a cutout of the cover panel. Accordingly, the open portion may assist in reducing material, mass, weight and cost of the XT. Furthermore, the open portion may provide access, such as for access by a ROV to devices, modules or components mounted or housed therebelow. The open portion of the roof may comprise a support member. The support member may also be used for at least partially supporting the ROV on the roof of the XT. The XT may have a plurality of support members located at the top portion of the XT. The plurality of support members may be dimensioned and distributed such that an ROV for performing operations on the XT cannot pass between the support members. In particular, a body of the ROV may be wider than the spacing of the support members and the ROV cannot fully pass through the support members. The support members may be configured to prevent the ROV inadvertently or accidentally damaging devices, components or modules housed or mounted within the XT. Within the XT may entail within a volume defined by the XT’s frame, roof and support members. The provision of the roof, with its protective cover and support members, may allow the ROV to be landed and supported on the XT. Accordingly, at least some XT operations performed by the ROV may be performed whilst the ROV is safely supported on the top of the XT. The support members may extend horizontally across part / s of the roof of the XT. In addition, the support members may also extend downwards from the top portion, such as projecting in front of respective side portions of the XT. Accordingly, the support members may also protect devices, components and modules housed or mounted on or in the XT from the sides, such as from lateral impact. In at least some examples, the support members can help prevent accidental damage such as otherwise could be associated with the ROV inadvertently bumping into the devices, components or modules. The XT may comprise a vertical XT (“VXT”). The XT may be configured for suspending a production tubing from a tubing hanger, mounted in the wellhead. The XT may comprise an electric XT (“eXT”). The XT may comprise electric actuators, such as for controlling valves. The XT may comprise an all-electric XT. All of the XT’s actuators may be electrical, such as driven by electric motors. The XT may only require an electrical supply for powering the XT. The electrical supply may be from surface, such as via a cable / s or an umbilical / s. In at least some examples, the XT may be an electric Vertical (“eVXT”). The XT’s support frame may define an internal volume therewithin for the mounting of plurality of devices, modules or components. Accordingly, the XT may be configured for suspending a production tubing from a tubing hanger, mounted in the wellhead. The XT may comprise a support frame with a vertical axis corresponding to a location of the master valve block (“MVB”) - and aligned with the tubing hanger and production tubing. For example the vertical axis may be a central vertical axis, located equidistant from four vertical posts defining four structural vertices of the XT’s frame. Accordingly, it will be appreciated that the XT may be placed centrally over the wellhead. The XT may have a centre of gravity located centrally both vertically and horizontally. For example, the centre of gravity may be at a central point defined as the geometrical centre of a cube or cuboid defined by the XT support frame, such as based upon the four posts. It will be appreciated that the posts can provide for installation of the XT, such as on a template on a seabed. The XT may have a top portion, effectively defined as a horizontal plane at the top of the XT frame. The XT may comprise a ROV panel that provides numerous interfaces and indicators for use by the ROV. For example, various status indicators on the ROV can be viewed with a ROV camera. Likewise, the ROV can perform functions at the ROV panel, such as adjusting settings, operating overrides, switches, actuators or the like. The ROV can also be used to make or break connections, depending on operations being performed - such as removing or installing connectors, or other components, devices or modules. It will be appreciated that the ROV can be positioned in front of the ROV panel for performing such operations. The XT may have a number of bars that can be used to assist the ROV, such as being used as grab bars by a ROV gripper / s - as well as the bars offering protection (e.g. from accidental impact) for adjacent components, devices or modules. The XT may comprise one or more hatches. The hatch / es may be for selectively providing access. The hatch / es may comprise an access hatch / es. The hatch / es may be for protecting components therebehind. In at least some examples, the hatch / es may be positioned above a component / s. The hatch / es may be positioned above a component / s to protect a component / s therebelow. For example, the hatch / es may comprise a protective hatch / es. The hatch / es may provide a dropped object protection (e.g. to protect a component / s therebelow from an object from above falling onto the component / s). The hatch / es may be selectively openable. The hatch / es may be selectively openable by a ROV, such as with a manipulator, grabber or arm of a ROV. The hatch / es may be selectively closable, such as by a ROV. The hatch / es may be horizontal when closed. Optionally, the hatch / es may be horizontal when opened. The hatch / es may comprise an access door. The hatch / es may be hinged. The hatch / es may be hinged for manipulation about a horizontal hinge access between a horizontal closed position and a horizontal opened position. When opened, the hatch may rest upon a portion of the XT. The portion upon which the hatch may rest may include another hatch (e.g. another adjacent hatch). The another hatch may comprise a closed (e.g. when it is supporting a first hatch thereupon). Accordingly, the method may comprise opening a hatch, with a ROV (e.g. grabber, manipulator or arm); accessing a component behind (or below) the hatch, such as to inspect, adjust, install, remove or operate with the ROV; and thereafter closing the hatch, with the ROV. The XT may be configurable to add or remove the hatch / es. For example, the XT may comprise mounting points for the hatch / es. The hatch / es may be selectively mounted, such as dependent upon a condition of operation of the XT, such as its deployment location. For example, the XT may comprise the hatch / es when deployed in deepwater locations. The XT may comprise a vertical arrangement of zones or portions for housing the plurality of devices, modules or components. The XT may comprise a top, defined or covered by the roof; and a bottom, defined by a base. The XT may comprise an intermediate support member located intermediate the bottom and the top. The intermediate support member may comprise a shelf, such as for compartmentalising the zones or portions. The shelf may comprise a mounting for one or more of the devices, modules or components. The shelf may extend laterally. The shelf may extend laterally beyond the footprint of the XT, such as defined by the base. The shelf may extend laterally beyond the roof panel. The support members may extend downwards from the roof to suspensively support the shelf at a front edge, the support members being connected thereto, distributed along the front edge. The shelf may support a plurality of modules. The modules may be vertically accessible on the shelf. For example, the modules may be directly accessible from above. The modules may be vertically retrievable and / or insertable in the shelf. The shelf may comprise an opening, such as a throughhole, for receiving one or more of the devices, modules or components therein. The shelf may comprise a plurality of through-holes for receiving devices, components or modules. The shelf may comprise the plurality of throughholes for receiving the plurality of modules therein, such that the modules are accessible from above. In at least some examples, the modules are also installable by tion into the throughholes from above. The through-holes may be sized for receiving corresponding devices, components or modules therein. It will be appreciated that the devices, components or modules may be installed by insertion from above. In at least some examples, the respective through-holes may be for first and second actuator control modules (“ACMs”) and a Power and Communication Gateway Module (“PCGM”), such as disclosed in UK Patent Application GB2303299.8, the contents of which may be incorporated for herein by reference. The respective modules may be installed on the XT by insertion from above, with each module being sized and dimensioned to pass through the respective opening in the shelf. The throughholes may act as guideholes for the installation of the modules. Each module may have a shoulder, flange or mounting bracket or plate for mounting the module on the shelf. At least some, if not most, of the module may project downwards below the shelf, with a top portion of each module being accessible above the shelf. It will be appreciated that the modules may be fixed to the shelf (e.g. with fasteners, bolts, etc.). Accordingly, the shelf may support a plurality of modules such that they may be accessible on the shelf. For example, the modules may be directly accessible from above; and also from the front. It will be appreciated that each of the modules is vertically retrievable and (re)insertable in the shelf. Indeed, if required, a module may be removed or added. The provision of the shelf and its mounting locations for the modules, with the shelf laterally extending out from the XT frame may effectively provide the modules at an exterior of the XT. Accordingly, the accessibility of the modules may be enhanced, with the modules being accessible from above; and also from the front. Accordingly, in at least one aspect, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising a shelf. A front edge of the shelf may be non-linear. The front edge of the shelf may comprise a plurality of outwardly projecting portions. The plurality of outwardly extending projections may be distributed along a length of the front edge of the shelf. The distribution may be irregular. The outwardly extending projections may be configured to protect one or more flying leads, such as electrical flying leads (“EFLs”). Accordingly, in at least some examples, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising a shelf, a front edge of the shelf being non-linear, comprising a plurality of outwardly projecting portions distributed along a length of the front edge of the shelf, the outwardly extending projections being configured to protect one or more electrical flying leads (“EFLs”). For example, the outwardly extending projections may extend outwardly by a distance equal to or greater than a diameter of a EFL. Accordingly, the outwardly extending projections may extend further outwardly than an EFI, such as an EFL pressed against the front edge of the shelf (e.g. by a lateral impact, or other object pressing sideways against the XT, such as athe ROV). Between the outwardly extending projections, such as a pair of adjacent outwardly extending projections, there may be provided a trough. The trough may be for receiving an intermediate portion of one or more EFLs therein. The trough / s may be effectively be a horizontal recess. For example, when viewed from above, the horizontal shelf may have inwardly extending troughs, and outwardly extending projections. The trough / s may be configured to receive intermediate portions of EFLs, such as EFLs pressed there against. Accordingly, the EFLs may be protected and damage to the EFLs at least mitigated in an event of an object pressing against the side of the XT with the shelf / ves. The front edge of the shelf may be scalloped along its length. The shelf may effectively have cut-outs. The cut-outs may reduce material, mass, weight and cost of the XT. The shelf may be scalloped along its front edge, corresponding to parking locations for various connectors or contacts. The parking locations may be at the outwardly projecting portions of the front edge of the shelf. These projecting portions may provide an increased effective width, providing more room and support for the parking locations. Furthermore, the outward extension of the shelf as such and also its front edge projections for the parking locations may enhance accessibility of the parking locations by the ROV. It will be appreciated that the ROV can remove connectors from parking positions and hook up elsewhere on the XT. The provision of the outwardly-extending shelf, along with its projecting parking locations may help to prevent the ROV contacting any of the other flying leads (EFLs / EOFLs, etc.). Accordingly, risk of damage to EFLs or entanglement of the ROV may be mitigated. During XT installation or Workover, access by the ROV to the roof of the XT may be impeded. Accordingly, to ensure that the ROV can connect to the PCGM, the PCGM may have EFLs (PA&PB) pre-installed to parkings on the ROV Panel prior to XT deployment - such that the ROV can connect to the PCGM from the front of the XT. Likewise, if any EFLs may be required for a workover, they may be installed prior to a Workover Stack blocking ROV access to the PCGM. It will be appreciated that the ROV may comprise a ROV with XT and / or BOP operational functionality. For example, the ROV may comprise one or more arms, grabbers, manipulators, tools, or the like. The ROV may be complaint with API standard 53 for performing BOP interventions. The standard may be the latest released applicable version at the effective filing date of this patent application (e.g. 5th edition, published May 2023). The ROV may comprise a subsea intervention ROV. The ROV may comprise a work class ROV. The ROV may comprise a constructor work class ROV. The ROV may comprise a lift ROV. The ROV may comprise a depth rating of at least 2,000m. In at least some examples, the ROV may comprise a depth rating of 6,000m or more. The ROV may comprise a deepwater ROV. The ROV may be configured to manipulate one or more actuators, switches or tools on the XT. The ROV may be configured to lift a payload of at least 30kg. In at least some examples, the ROV may be configured to lift payloads of at least 100kg; and optionally 200kg or more. The ROV may comprise a lift capacity of 1,000kg or more (e.g. a through-frame lift capacity). The ROV may comprise an in-air weight of at least 1,000kg. The ROV may comprise an in-air weight of at least 2,000kg. In at least some examples, the ROV comprises an in-air weight of at least 4,000kg. The XT may be configured to support the in-water weight of the ROV thereupon. In at least some examples, the XT may be configured to support the in-air weight of the ROV thereupon. It will be appreciated that, generally, the ROV can access the PCGM from the front of the XT or the roof of the XT, utilising the open portion thereof. Accordingly, in at least one aspect, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising a Power and Communication Gateway Module (“PCGM”), the PCGM being accessible by an ROV from the front of the XT and a roof of the XT. The ROV panel may be accessible with a ROV positioned in front of the ROV panel. It will be appreciated that the ROV can use the XT for stabilization (e.g. gripping with a ROV gripper / arm). For example there may be provided grab bars that can assist the ROV in positioning and stability. For example, the ROV can grip one or more of the grab bars to reduce relative movement between the ROV and the XT. This can be particularly helpful when the ROV is exerting a force or torque (e.g. on a component of the XT) or where example the ROV is performing an operation that may require a level of precision, such as manipulating a connector. It will be appreciated that the ROV panel itself may act as a protective cover for equipment therebehind, such as numerous EFLs. In particular, the left hand side of the face of the XT with the ROV panel may not be covered by the ROV panel. For example, various connectors, connection points and EFLs may be exposed. For example, access points for chemical injection valves (CIVs) may be located adjacent the ROV panel, accessible from in front of the ROV panel. Whilst such equipment may not be routinely necessarily accessible, the ROV may require such access for particular operations. Whereas the components on the ROV panel may be typically more regularly accessed or viewed, the components in the adjacent unpanelled portion may be generally only occasionally accessed. Whilst these components could also be protected by a panel, such as by lengthening the ROV panel sideways (to the left) or adding a separate panel, the panel would need to be removable or openable (e.g. a hinged door) to enable the occasional access to the components. Furthermore, many EFLs and connectors would undesirably protrude from the ROV panel if mounted thereon. Accordingly, these components may be recessed, in a plane behind the ROV panel. For example, no EFLs or the like protrude in front of the ROV panel - mitigating undesirable damaging of the EFLs or entanglement of the ROV. Furthermore, there may be provided a protective member to further mitigate damage to the EFLs and adjacent components. The protective member may be a horizontal bar extending fully across the front of the opening. The protective member may be positioned in front of all the EFLs, but rearwards of the grab bars. The protective member may also act as a mount for the EFLs. For example, intermediate portions of the EFLs (intermediate connections at each end of the respective EFLs) may be fastened to the rear of the protective member (e.g. tie-wrapped with cable-ties or the like). Accordingly, the EFLs can be protected from damage, particularly during XT installation. If required, EFLs can be retrieved after XT installation, such as with the ROV loosening or severing the fastenings (e.g. cutting, bursting or breaking the cable-ties). Accordingly, in at least one aspect, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising a protective member configured to mitigate damage to electrical flying leads (“EFLs”) and adjacent components, the protective member providing mountings for intermediate portions of the EFLs. The XT may have valves mounted rearwards (e.g. with the end which normally faces outwards on the tree housing facing inwards, as shown). For example, at least one CIV may be installed with its indicator accessible, such as for possible manipulation with a ROV grabber to push the indicator (adjust the valve). Furthermore, such reversal of the valves may improve routing of the associated cabling, such as improving cable length efficiency. Accordingly, in at least one aspect, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising at least one rear-mounted valve, such that the valve is installed with its indicator accessible by a ROV. The XT may have a number of actuatable valves mounted to it. In this example, the XT is an electric Vertical XT (“eVXT”). Accordingly, it will be appreciated that the valves can be electrically actuatable, such as driven by electric rotary drive motors. Roller screw assemblies within the actuators can convert the electric rotary drive to linear motion, so as to selectively open and close valves, such as gate valves for controlling a fluid flow or supply. The actuator may comprise an actuator linear drive module (“ALDM”), connected for example to an actuator rotary drive module (“ARDM”), which in turn may be connected to an Actuator Control Module (“ACM”). It will be appreciated that the ACM may comprise an actuator electronics control module (“AECM”). The electronics, such as the AECM, may be mounted in a perpendicular orientation to the actuator. Accordingly, in at least one aspect, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising an actuator and electronics for controlling the actuator, wherein the electronics is mounted perpendicularly to the actuator. This may provide benefits over the conventional arrangements of the electronics being mounted colinearly with the actuator. The electronics, housed in the ACM, may be arranged in a vertically-oriented module canister. The electronics may be attached below the drive. Accordingly, the electronics module may not protrude laterally; and the electronics module may thereby protected from damage. No part of the actuator, including the electronics module, may protrude laterally beyond an adjacent protective grab bar. It will be understood that a method of installing the actuators, drive modules and electronics (control) modules may therefore involve a horizontal installation, sliding the components laterally into holes for receiving the components. For example, the ACM mounted to the ARDM can be installed as a combined unit The combined unit can be readily suspended, with the vertically-oriented ACM ensuring that the combined unit is balanced and easily manoeuvrable for insertion for coupling with the ADLM - sliding horizontally for mating with the ALDM. The connections of a power and communication interface of the actuator may be directed inwards, towards the centre of the XT. Accordingly, the power and communication interface may be protected from the exterior of the XT. Furthermore, orienting the power and communication interface towards the centre of the XT may enhance the routing of connections thereto, such as directly or indirectly from the PCGM. A component funnel may be provided, such as for a downhole interface unit (“DIU”). The component funnel may comprise integrated parkings and bulkhead connectors. Accordingly, in at least one aspect, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising a component funnel comprising integrated parkings and bulkhead connectors. The funnel may have a lowered mounting flange such that the DIU is offset upwards and within operating range of a ROV manipulator arm. For example, the ROV on the roof of the XT may readily access the DIU from above. The top of the funnel and the associated parkings and bulkhead connectors may be proud of the housing, protruding above the housing. Accordingly, access and manipulation by the ROV may be improved. The component funnel may comprise a J-Lock for securing the component therein. The J-Lock may comprise a visual indicator, such as for visually indicating correct securement or locking of the component therein. Accordingly, the component funnel may comprise a ROV friendly J-Lock with visual indicator. Such a component funnel may be relatively compact, optimising space and reduce overall XT cost (e.g. compared to a conventional component funnel mounted flush in the housing). On an opposite side face of the XT from the side face of the XT with the shelf supporting the PCGM, there may be provided a shelf intermediate the top and bottom of the XT. The shelf may be supported at its front edge by the overhanging support members connected to the roof. For example the shelf may be configured for receiving and housing a plurality of containers. The containers for example may be for subsea hydraulic power units (“SHPUs”). The shelf may comprise a plurality of funnels. Accordingly, in at least one aspect, there is provided a subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising a shelf with a plurality of funnels. The funnels may be attached to, and supported by, the XT at intermediate portions, shown for example as in the horizontal middle of the funnels. Accordingly, the weight of the SHPUs is supported at middle portions of the funnels. As with the protruding shelf with the PCGM, the second shelf also effectively laterally protrudes from the frame of the XT. Accordingly, the funnels may be readily accessible, such as for the ROV to access the funnels such as for installation, inspection, connection or replacement of the containers received in the funnels. It will be appreciated that the containers can be readily inserted and removed from the funnels vertically from above. The funnels may be free at their bottom ends. Supporting the funnels only in the middle may allow an associated flange to take the downwards weight, thereby reducing complexity (e.g. compared to conventional funnels) and avoiding having a lower shelf (below the funnel, to support the funnel at its bottom). It will also be appreciated that providing the funnels at the exterior of the XT frame may allow for a removable and replaceable bank of bottles for the SHPUs. Accordingly, the XT can accommodate larger (e.g. wider) bottles than may otherwise be possible. Furthermore, the XT can readily be reconfigured for a variety of uses, such as by readily adapting the configuration of the funnels provided. Accordingly, an array of XT’s with varying funnels can be provided, based upon a same XT frame. According to an aspect, there is provided a system comprising the XT of any aspect, example, embodiment or claim; and a ROV. According to an aspect, there is provided a wellhead comprising the XT of any aspect, example, embodiment or claim. According to an aspect, there is provided a method of performing operations with a Remotely Operated Vehicle (“ROV”) on a subsea vertical Xmas Tree (“XT”) on a wellhead, the method comprising supporting the ROV on a roof of the XT and performing operations with the ROV therefrom. The method may comprise supporting the ROV on the roof of the XT on a roof cover panel and an open roof portion, the open roof portion supporting the ROV with at least one horizontal support member. The method may comprise providing an electric actuator with the XT, the actuator comprising an electronics module perpendicularly oriented to the actuator linear drive module (“ALDM”); and wherein the method comprises horizontally sliding the electronics module to mate with the ALDM. The method may comprise installing a Power and Communication Gateway Module (“PCGM”) on the XT, the PCGM being installed by vertical insertion into a receiving throughhole located in a support shelf, the shelf being positioned at an exterior of the XT intermediate a top and a bottom of the XT. The method may comprise accessing or operating the PCGM with a ROV, the ROV being located on either of the roof of the XT or in front of the XT. According to an aspect, there is provided a well completion assembly comprising a wellhead having mounted thereon a XT according to any other aspect, example, claim or embodiment; and optionally a tubing hanger mounted in the wellhead. According to an aspect, there is provided a method of using the system, such as comprising the XT, according to an aspect, claim, embodiment or example of this disclosure. The steps of the method may be in any order. According to an aspect, there is provided an apparatus configured to perform a method according to an aspect, claim, embodiment or example of this disclosure. Within the scope of this disclosure it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: FIG. 1 shows a schematic view of a XT according to the present disclosure, from a first angle; FIG. 2 shows the XT of FIG. 1, from a second angle; FIG. 3 shows a portion of the XT of FIG. 1; FIG. 4 shows the portion of the XT of FIG. 3 from another angle; FIG. 5 shows the XT of FIG. 1, from a top plan view; FIG. 6 shows a portion of a top plan view of the XT of FIG. 1; FIG. 7 shows a view of a right side of the XT of FIG. 1; FIG. 8 shows a view of a front of the XT of FIG. 1; FIG. 9 shows a partial front view of the XT of FIG. 1; FIG. 10 shows a detail view of a portion of the front of the XT of FIG. 1; FIG. 11 shows a view of another portion of the front of the XT of FIG. 1; FIG. 12 shows a detail view of FIG. 11; FIG. 13 shows another partial front view of the XT of FIG. 1; FIG. 14 shows a partial assembly view of the portion of FIG. 13; FIG. 15 shows a view of a left side of the XT of FIG. 1; FIG. 16 shows a detail view of a portion of the XT of FIG. 1; FIG. 17 shows another detail view of a portion of the XT of FIG. 1; FIG. 18 shows a schematic top view of the XT of FIG. 1 in a further configuration; and FIG. 19 shows a portion of the top of the XT of FIG. 1 in a yet further configuration. DETAILED DESCRIPTION Referring firstly to Figure 1, there is shown a XT 10 according to the present disclosure. Here the XT 10 is an all-electric, vertical XT 10. Accordingly, the XT 10 is configured for suspending a production tubing from a tubing hanger, mounted in the wellhead. As can be seen in Figure 1, the XT 10 comprises a support frame 12 with a vertical axis 14 corresponding to a location of the master valve block (“MVB”) - and aligned with the tubing hanger and production tubing. It will be appreciated that the XT 10 can comprise blocks and valves, such as disclosed in International Application No. PCT / NO2020 / 050205, published as WO 2021 / 029776 A1, the contents of which are incorporated herein by reference. Here the vertical axis 14 is a central vertical axis 14, located equidistant from four vertical posts 18 defining four structural vertices of the XT 10’s frame 12. Accordingly, it will be appreciated that the XT 10 is placed centrally over the wellhead. Indeed, in the example shown, the XT 10 has a centre of gravity located centrally both vertically and horizontally. Here, the centre of gravity is at a central point defined as the geometrical centre of a cube or cuboid defined by the XT 10 support frame 12, such as based upon the four posts 18. It will be appreciated that the posts 18 can provide for installation of the XT 10, such as on a template on a seabed. The XT 10 has a top portion 20, effectively defined as a horizontal plane at the top of the XT 10 frame 12. Here, the XT 10 has a horizontal roof 22 that is configured to receive and support a ROV thereon. The ROV may be for performing operations on the XT 10, such as operating connections, performing inspections, checking statuses, installing and / or removing components or connections. As such, the ROV comprises a relatively substantial mass and volume (e.g. compared to other ROVs, not capable of performing such operations on XT 10s). The roof 22 shown here comprises a protective cover in the form of a horizontal, planar panel. The cover protects devices, modules or components housed thereunder. Furthermore, the cover provides a landing or even a docking location for a ROV thereon. The roof 22 here additionally comprises an open portion 26. The open portion 26 is devoid of the cover panel, effectively being formed by a cutout of the cover panel. Accordingly, the open portion 26 assists in reducing material, mass, weight and cost of the XT 10. Furthermore, the open portion 26 provides access, such as for access by a ROV to devices, modules or components mounted or housed therebelow. As can clearly be seen in Figures 1 and 2, the open portion 26 of the roof 22 has a support member. The support member 28 28 can also be used for at least partially supporting the ROV on the roof 22 of the XT 10. In the example shown here, the XT 10 has a plurality of support members 28, 28a, 28b, 28c, 28d, 28e, 28f located at the top portion 20 of the XT 10. The plurality of support members 28, 28a, 28b, 28c, 28d, 28e, 28f are dimensioned and distributed such that an ROV for performing operations on the XT 10 cannot pass between the support members 28, 28a, 28b, 28c, 28d, 28e, 28f, particularly a body of the ROV is wider than the spacing of the support members 28, 28a, 28b, 28c, 28d, 28e, 28f and the ROV cannot fully pass through the support members 28, 28a, 28b, 28c, 28d, 28e, 28f. The support members 28, 28a, 28b, 28c, 28d, 28e, 28f prevent the ROV inadvertently or accidentally damaging devices, components or modules housed or mounted within the XT 10 volume defined by the XT 10’s frame 12, roof 22 and support members 28, 28a, 28b, 28c, 28d, 28e, 28f. The provision of the roof 22, with its protective cover and support members 28, 28a, 28b, 28c, 28d, 28e, 28f, allows the ROV to be landed and supported on the XT 10. Accordingly, at least some XT 10 operations performed by the ROV can be performed whilst the ROV is safely supported on the top of the XT 10. In the example shown here, the support members 28, 28a, 28b, 28c, 28d, 28e, 28f extend horizontally across parts of the roof 22 of the XT 10. In addition, the support members 28, 28a, 28b, 28c, 28d, 28e, 28f here also extend downwards from the top portion 20, projecting in front of respective side portions of the XT 10. Accordingly, the support members 28, 28a, 28b, 28c, 28d, 28e, 28f also protect devices, components and modules housed or mounted on or in the XT 10 from the sides, such as from lateral impact. For example, the support members 28, 28a, 28b, 28c, 28d, 28e, 28f can help prevent accidental damage such as otherwise could be associated with the ROV inadvertently bumping into the devices, components or modules. The XT 10’s ROV Panel 30 is also clearly visible in Figure 1 (and in detail in Figures 8 and 9). The ROV Panel 30 provides numerous interfaces and indicators for use by the ROV. For example, various status indicators on the ROV can be viewed with a ROV camera. Likewise, the ROV can perform functions at the ROV Panel 30, such as adjusting settings, operating overrides, switches, actuators or the like. The ROV can also be used to make or break connections, depending on operations being performed - such as removing or installing connectors, or other components, devices or modules. It will be appreciated that the ROV can be positioned in front of the ROV Panel 30 for performing such operations. The XT 10 here has a number of bars 32 that can be used to assist the ROV, such as being used as grab bars 32 by a ROV gripper / s - as well as the bars 32 offering protection (e.g. from accidental impact) for adjacent components, devices or modules. Figure 2 shows the XT 10 from a different angle, again showing the ROV Panel 30. Also clearly visible in Figure 2 is a mounting shelf 31. The XT 10 comprises a vertical arrangement of zones or portions for housing the plurality of devices, modules or components. The XT 10 comprises the top, defined and covered by the roof 22; and a bottom 33, defined by a base 34. Here the shelf 31 defines an intermediate support member located intermediate the bottom 33 and the top. The shelf 31 comprises a mounting for one or more of the devices, modules or components. The shelf 31 extends laterally beyond the footprint of the base 34; and also of the roof panel 24. The support members 28, 28a, 28b, 28c extend downwards from the roof 22 to suspensively support the shelf 31 at a front edge 36, the support members 28, 28a, 28b, 28c being connected thereto, distributed along the front edge 36. Figures 3 and 4 shown the frame 12 of the XT 10, shown for illustrative purposes with devices, modules and components generally removed. As readily visible in Figures 3 and 4 in particular, the shelf 31 has a plurality of through-holes for receiving devices, components or modules. The through-holes are sized for receiving corresponding devices, components or modules therein. It will be appreciated that the devices, components or modules can be installed by insertion from above. In the example, shown here the respective through-holes are for first and second actuator control modules (“ACMs”) and a Power and Communication Gateway Module (“PCGM”), such as disclosed in UK Patent Application GB2303299.8, the contents of which are incorporated herein by reference. The respective modules can be installed on the XT 10 by insertion from above, with each module being sized and dimensioned to pass through the respective opening in the shelf 31. The throughholes 40, 42, 44 act as guideholes for the installation of the modules. Each module has a shoulder, flange or mounting bracket or plate for mounting the module on the shelf 31, with at least some, if not most, of the module projecting downwards below the shelf 31, with a top portion of each module being accessible above the shelf 31. It will be appreciated that the modules can be fixed to the shelf 31 (e.g. with fasteners, bolts, etc.). Accordingly, the shelf 31 supports a plurality of modules such that they are accessible on the shelf 31. Here, the modules are directly accessible from above; and also from the front. It will be appreciated that each of the modules is vertically retrievable and (re)insertable in the shelf 31. Indeed, if required, a module can be removed or added. The provision of the shelf 31 and its mounting locations for the modules, with the shelf 31 laterally extending out from the XT 10 frame 12 effectively provides the modules at an exterior of the XT 10. Accordingly, the accessibility of the modules is enhanced, with the modules being accessible from above, as shown in Figure 6; and also from the front, as shown in Figure 7. In the example shown here in Figure 2, the front edge 36 of the shelf 31 is scalloped along its length, as also visible in the top plan view of Figure 5. The shelf 31 effectively has cut-outs, again reducing material, mass, weight and cost of the XT 10. The shelf 31 is scalloped along its front edge 36, corresponding to parking locations 38 for various connectors or contacts. The parking locations 38 are at the outwardly projecting portions of the front edge 36 of the shelf 31. These projecting portions provide an increased effective width, providing more room and support for the parking locations 38. Furthermore, the outward extension of the shelf 31 as such and also its front edge 36 projections for the parking locations 38 enhances accessibility of the parking locations 38 by the ROV. It will be appreciated that the ROV can remove connectors from parking positions and hook up elsewhere on the XT 10. The provision of the outwardly-extending shelf 31, along with its projecting parking locations 38, helps to prevent the ROV contacting any of the other flying leads (EFLs / EOLFs, etc.). Accordingly, risk of damage to EFLs 50 or entanglement of the ROV is mitigated. During XT 10 installation or Workover, access by the ROV to the roof 22 of the XT 10 may be impeded. Accordingly, to ensure that the ROV can connect to the PCGM, the PCGM can have EFLs (PA&PB) pre-installed to parkings on the ROV Panel 30 prior to XT 10 deployment -such that the ROV can connect to the PCGM from the front of the XT 10, as shown in Figure 7. Likewise, if any EFLs are required for a workover, they can be installed prior to a Workover Stack blocking ROV access to the PCGM. It will be appreciated that, generally, the ROV can access the PCGM from the front of the XT 10 or the roof 22 of the XT 10, utilising the open portion 26 thereof. Referring now to Figures 8 and 9, there are shown front views of the side of the XT 10 with the ROV Panel 30. As shown, the ROV Panel 30 is accessible with a ROV positioned in front of the ROV Panel 30. It will be appreciated that the ROV can use the XT 10 for stabilization (e.g. gripping with a ROV gripper / arm). Here there are provided grab bars 32 that can assist the ROV in positioning and stability. For example, the ROV can grip one or more of the grab bars 32 to reduce relative movement between the ROV and the XT 10. This can be particularly helpful when the ROV is exerting a force or torque (e.g. on a component of the XT 10) or where the ROV is performing an operation that may require a level of precision, such as manipulating a connector. It will be appreciated that the ROV Panel 30 itself acts as a protective cover for equipment therebehind, such as numerous EFLs 50. However, as clearly visible in Figures 8 and 9, the ROV Panel 30 does not cover the entire side of the XT 10. In particular, the left hand side of the face of the XT 10 with the ROV Panel 30 is not covered by the ROV Panel 30, shown in detail in Figure 10. Here, various connectors, connection points and EFLs 50 are exposed. For example, access points for chemical injection valves (CIVs) 52a, 52b are located adjacent the ROV Panel 30, accessible from in front of the ROV Panel 30. Whilst such equipment may not be routinely necessarily accessible, the ROV may require such access for particular operations. Whereas the components on the ROV Panel 30 are typically more regularly accessed or viewed, the components in the adjacent unpanelled portion are generally only occasionally accessed. Whilst these components could also be protected by a panel, such as by lengthening the ROV Panel 30 sideways (to the left) or adding a separate panel, the panel would need to be removable or openable (e.g. a hinged door) to enable the occasional access to the components. Furthermore, many EFLs and connectors would undesirably protrude from the ROV Panel 30 if mounted thereon. Accordingly, these components are recessed, in a plane behind the ROV Panel 30. Hereby, no EFLs 50 or the like protrude in front of the ROV Panel 30 - mitigating undesirable damaging of the EFLs 50 or entanglement of the ROV. Furthermore, there is provided a protective member to further mitigate damage to the EFLs 50 and adjacent components. The protective member here is a horizontal bar extending fully across the front of the opening. The protective member is positioned in front of all the EFLs 50, but rearwards of the grab bars 32. The protective member here also acts as a mount for the EFLs. In the example shown here, intermediate portions of the EFLs (intermediate connections at each end of the respective EFLs) are fastened to the rear of the protective member (e.g. tie-wrapped with cable-ties or the like). Accordingly, the EFLs can be protected from damage, particularly during XT 10 installation. If required, EFLs can be retrieved after XT 10 installation, such as with the ROV loosening or severing the fastenings (e.g. cutting, bursting or breaking the cable-ties). As also visible in Figures 8 through 10; and shown in more detail in Figures 11 and 12, the XT 10 has valves mounted rearwards (e.g. with the end which normally faces outwards on the tree housing facing inwards, as shown). As shown here, at least two of the CIVs 52a, 52b are installed with their indicators 54a, 54b accessible, such as for possible manipulation with a ROV grabber to push the indicator 54a, 54b (adjust the valve). Furthermore, such reversal of the valves improves routing of the associated cabling, such as improving cable length efficiency. As visible in the ROV Panel 30 shown in Figures 8 and 9, the XT 10 has a number of actuatable valves mounted to it. In this example, the XT 10 is an electric Vertical XT 10 (“eVXT 10”). Accordingly, it will be appreciated that the valves can be electrically actuatable, such as driven by electric rotary drive motors. Roller screw assemblies within the actuators 60 can convert the electric rotary drive to linear motion, so as to selectively open and close valves, such as gate valves for controlling a fluid flow or supply. One of the actuators 60 is shown in detail in Figure 13, with Figure 14 showing a partially exploded view, indicative of how the actuator 60 can be assembled and installed. The actuator 60 here has an actuator linear drive module (“ALDM”) 62, connected here to an actuator rotary drive module (“ARDM”) 64, which in turn is connected to an Actuator Control Module (“ACM”) 66. It will be appreciated that the ACM 66 comprises an actuator electronics control module (“AECM”). Conventionally, the electronics module 66 (here in the ACM) is mounted colinearly with the actuator, for controlling the actuator 60. In contrast, here the electronics 66 are mounted in a perpendicular orientation to the actuator 60. The electronics 66, housed in the ACM, are arranged in a vertically-oriented module canister. As shown in Figures 13 and 14, the electronics 66 are attached below the drive 64. Accordingly, the electronics module 66 does not protrude laterally; and the electronics module 66 is thereby protected from damage. As shown here, no part of the actuator 60, including the electronics module 66, protrudes laterally beyond an adjacent protective grab bar 32. It will be understood that a method of installing the actuators 60, drive modules 64 and electronics (control) modules 66 therefor involves a horizontal installation, sliding the components laterally into holes for receiving the components. As shown in Figure 14, the ACM 66 mounted to the ARDM 64 can be installed as a combined unit. The combined unit can be readily suspended, with the vertically-oriented ACM 66 ensuring that the combined unit is balanced and easily manoeuvrable for insertion for coupling with the ADLM 62 - sliding horizontally for mating with the ALDM 62. As also visible in Figure 14, it can be seen that the connections of a power and communication interface 68 of the actuator 60 are directed inwards, towards the centre of the XT 10. Accordingly, the power and communication interface 68 is protected from the exterior of the XT 10. Furthermore, orienting the power and communication interface 68 towards the centre of the XT 10 enhances the routing of connections thereto, such as directly or indirectly from the PCGM 43. Referring now to Figure 15, there is shown an opposite side face of the XT 10 from the side face of the XT 10 with the shelf 31 supporting the PCGM 43. When viewing the ROV Panel 30, the PCGM side of the XT 10 can be considered as the right side; and the opposite side (shown in Figure 15) as the left side. This opposite side also comprises a shelf 70 intermediate the top and bottom 33 of the XT 10. Again the shelf 70 is supported at its front edge by the overhanging support members 28d, 28e, 28f connected to the roof 22. Here the shelf 70 is configured for receiving and housing a plurality of containers 72. The containers 72 here are for subsea hydraulic power units (“SHPUs”). The shelf 70 comprises a plurality of funnels 74. The funnels 74 are attached to, and supported by, the XT 10 at intermediate portions, shown here as in the horizontal middle of the funnels 74. Accordingly, the weight of the SHPUs is supported at middle portions of the funnels 74. As with the protruding shelf 31 with the PCGM, the second shelf 70 also effectively laterally protrudes from the frame 12 of the XT 10. Accordingly, the funnels 74 are readily accessible, such as for the ROV to access the funnels 74 such as for installation, inspection, connection or replacement of the containers received in the funnels 74. It will be appreciated that the containers can be readily inserted and removed from the funnels 74 vertically from above. The funnels 74 here are free at their bottom ends. Supporting the funnels 74 only in the middle means that an associated flange can take the downwards weight, thereby reducing complexity (e.g. compared to conventional funnels 74) and avoids having a lower shelf. It will also be appreciated that providing the funnels 74 at the exterior of the XT 10 frame 12 allows for a removable and replaceable bank of bottles for the SHPUs. Accordingly, the XT 10 can accommodate larger (e.g. wider) bottles 72 than may otherwise be possible. Furthermore, the XT 10 can readily be reconfigured for a variety of uses, such as by readily adapting the configuration of the funnels 74 provided. Accordingly, an array of XTs 10 with varying funnels 74 can be provided, based upon a same XT frame 12. Referring now to Figures 16 and 17, there is shown an example of a component funnel 80. The component funnel 80 shown is that of a downhole interface unit (“DIU”), also visible in Figure 5. The component funnel has integrated parkings and bulkhead connectors 82. The funnel has a lowered mounting flange such that the DIU is offset upwards and within operating range of a ROV manipulator arm. For example, the ROV on the roof 22 of the XT 10 can readily access the DIU from above, as clearly visible in Figure 5. The top of the funnel 80 and the associated parkings and bulkhead connectors 82 are proud of the housing, protruding above the housing. Accordingly, access and manipulation by the ROV is improved. As can be seen, the component funnel 80 has a ROV friendly J-Lock with visual indicator. Such a component funnel 80 as the DIU Funnel 80 shown is relatively compact, optimising space and reducing overall XT 10 cost (e.g. compared to a conventional component funnel 80 mounted flush in the housing). It will be appreciated that the XT 10 may be connected to a flow base. Accordingly, the flowlines may remain connected when removing the XT 10 (e.g. for workover, etc.). Referring now to Figures 18 and 19, there is shown a top portion of the XT 10. Here, a plurality of access hatches 90a, 90b, 90c, 90d, 90e, 90f, 90g have been added to the XT 10. The hatch / es 90a, 90b, 90c, 90d, 90e, 90f, 90g are for selectively providing access by a ROV 100 (portion of which shown schematically in Figure 19). The hatch / es 90a, 90b, 90c, 90d, 90e, 90f, 90g protect components therebehind, being positioned here above components, such as the PCGM 43,to protect components therebelow (e.g. to protect components therebelow from an object from above falling onto the components). As shown in Figure 19, the hatches 90a, 90b, 90c, 90d, 90e, 90f, 90g are selectively openable by a ROV 100, such as with a manipulator, grabber or arm of the ROV 100. As shown in Figure 19, the ROV 100 has opened hatches 90a, 90b, 90d by lifting the hatches and rotating about their respective horizontal hinges (e.g. relative to closed positions of hatches 90a, 90b and 90d in Figure 18). Accordingly, the ROV 100 can access components below, as shown in Figure 19. Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The applicant indicates that aspects of the present disclosure may consist of any such individual feature or combination of features. It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing from the scope of the disclosure. For example, it will be appreciated that although generally shown here with single windows, other examples comprise further windows. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims, including with equivalence.

Claims

1. A subsea vertical Xmas Tree (“XT”) for a wellhead, the XT comprising a roof, wherein the roof is configured to receive and support a Remotely Operated Vehicle (ROV) thereon.

2. The XT of claim 1, wherein the XT is configured for a ROV to perform operations on the XT whilst supported on the roof, the operations to be perfomed including at least one of: operating connections or other devices, performing inspections, checking statuses, installing and / or removing components or connections.

3. The XT of claim 1 or 2, wherein the roof comprises a protective cover in the form of a horizontal, planar panel that protects devices, modules or components housed thereunder; and the roof further comprises an open portion devoid of the cover panel, the open portion providing access by a ROV to devices, modules or components mounted or housed therebelow; and wherein the open portion comprises at least one support member for at least partially supporting a ROV on the roof of the XT.

4. The XT of claim 3, wherein the XT comprises a plurality of support members located at a top portion of the XT, the plurality of support members being dimensioned and distributed such that a ROV for performing operations on the XT cannot pass between the support members.

5. The XT of claim 4, wherein the plurality of support members extend horizontally across at least a part of the roof of the XT and also extend downwards from the top portion, so as to project in front of one or more side portions of the XT, thereby protecting devices, components and modules housed or mounted on or in the XT from lateral impact.

6. The XT of claim 4 or 5, wherein the XT comprises a vertical arrangement of zones or portions for housing the plurality of devices, modules or components, the XT comprising a shelf intermediate a top and bottom of the XT for compartmentalising the zones or portions, the shelf comprising a mounting for one or more of the devices, modules or components, wherein the plurality of support members extend downwards from the roof to suspensively support the shelf at a front edge, the support members being connected thereto, distributed along the front edge.

7. The XT of claim 6, wherein the front edge of the shelf is non-linear, comprising a plurality of outwardly projecting portions distributed along a length of the front edge of the shelf, the outwardly extending projections being configured to protect one or more electrical flying leads (“EFLs”).

8. The XT of claim 7, wherein the front edge of the shelf is scalloped along its length, the scalloping corresponding to parking locations for connectors or contacts, the parking locations being sited at the outwardly projecting portions of the scalloped front edge of the shelf.

9. The XT of any of claims 6 to 8, wherein the shelf extends laterally beyond a footprint of the XT; and the shelf supports a plurality of modules, the modules being vertically accessible on the shelf for retrieval and / or insertion and / or operation / inspection of the module in the shelf.

10. The XT of claim 9, wherein the shelf comprises a plurality of throughholes for receiving the plurality of modules therein, such that the modules are accessible from above and also installable by insertion from above.

11. The XT of claim 10, wherein the respective through-holes are for at least one actuator control module (“ACM”) and a Power and Control Gateway Module (“PCGM”), with the provision of the shelf laterally extending out from the XT frame positioning the modules at an exterior of the XT such that the modules are accessible from above; and also from a front of the XT.

12. The XT of any preceding claim, wherein the XT comprises at least one electric actuator for actuating a valve, the actuator comprising an electronics module mounted in a perpendicular orientation to the actuator.

13. The XT of claim 12, wherein the electronics module is mounted vertically, suspended below a rotary drive module, with the electronics module being installable together with the rotary drive module by horizontal sliding into an actuator linear drive module.

14. The XT of any preceding claim, wherein the XT comprises a component funnel for receiving a component, such as a unit or module therein, the component funnel comprising integrated parkings and bulkhead connectors at a top of the funnel; and wherein the funnel comprises a lowered mounting flange such that the component mounted therein is offset upwards, protruding above a mounting or surface of a housing therebelow.

15. The XT of claim 14, wherein the component funnel is configured to receive a downhole interface unit (“DIU”); and the component funnel comprise a ROV-friendly J-Lock with visual indicator.

16. The XT of any preceding claim, wherein the XT comprises one or more access hatches for selectively providing access, the hatch / es being positioned above a component / s to provide dropped object protection to a component / s therebelow.

17. The XT of claim 16, wherein the hatch / es are selectively openable by a ROV, the hatch / es being horizontal when closed; and the hatch / es being hinged for manipulationabout a horizontal hinge access between a horizontal closed position and a horizontal opened position.

18. The XT of any preceding claim, wherein the XT comprises an all-electric vertical XT.

19. A system comprising the XT of any preceding claim and a ROV.

20. A wellhead comprising the XT of any of claims 1 to 18.

21. A method of performing operations with a Remotely Operated Vehicle (“ROV”) on a subsea vertical Xmas Tree (“XT”) on a wellhead, the method comprising supporting the ROV on a roof of the XT and performing operations with the ROV therefrom.

22. The method of claim 21, wherein the method comprises supporting the ROV on the roof of the XT on a roof cover panel and an open roof portion, the open roof portion supporting the ROV with at least one horizontal support member.

23. The method of claim 21 or 22, wherein the method comprises providing an electric actuator with the XT, the actuator comprising an electronics module perpendicularly oriented to the actuator linear drive module (“ALDM”); and wherein the method comprises horizontally sliding the electronics module to mate with the ALDM.

24. The method of any of claims 21 to 23, wherein the method comprises installing a Power and Communication Gateway Module (“PCGM”) on the XT, the PCGM being installed by vertical insertion into a receiving throughhole located in a support shelf, the shelf being positioned at an exterior of the XT intermediate a top and a bottom of the XT.

25. The method of claim 24, wherein the method comprises accessing or operating the PCGM with a ROV, the ROV being located on either the roof of the XT or in front of the XT.

Citation Information

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