APPARATUS AND METHOD FOR SUBSEA EQUIPMENT REMOVAL AND INSTALLATION

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to United Kingdom Patent Application No. GB2413702.8, filed on Sep. 17, 2024 at the United Kingdom Intellectual Property Office, the disclosure of which is incorporated herein in their entirety by reference

FIELD OF THE INVENTION

The present invention relates to a tool for removal and installation of subsea equipment, such as a gasket, from, for example, a subsea wellhead, subsea riser systems or other subsea equipment and a method relating thereto.

BACKGROUND TO THE INVENTION

Subsea gaskets are a specialized sealing component commonly used with high-pressure applications, such as subsea wellheads subsea riser systems, subsea production systems and other subsea equipment. In subsea wellhead equipment, gaskets are crucial for maintaining well integrity and preventing environmental hazards. However, gaskets are often required to be removed from the subsea equipment for various reasons such as replacement after disconnecting during drilling, production, workover or decommissioning activities. The removal of gaskets from equipment in subsea environments can be particularly challenging due to a number of factors.

Namely, the immense pressures, harsh conditions and ocean currents at subsea depths, as well as the inherent limited visibility thereof complicate the process of gasket removal and installation. Furthermore, gaskets frequently become stuck in position for a wide variety of reasons such as, for example, corrosion of the gasket due to prolonged exposure to seawater or galvanic corrosion; thermal expansion and contraction of both the gasket and the subsea equipment (which can lead to a tight bond between the gasket and the wellhead) caused by the associated fluctuations in temperatures experienced during drilling and production activities; adherence of marine life such as bio fouling on and around the subsea components, various chemical reactions which can cause the gasket to adhere to the seal preparation and oversized or poorly manufactured gaskets which become stuck due to increased interference or misaligned make up due to poor manufacture or misaligned installation.

In this connection, there are a currently a number of tools in the field used for removing gaskets from subsea wellheads.

In this respect, common techniques for the removal of gaskets from subsea wellheads require the use of remotely operated vehicles (ROVs) which typically have grab arms configured to physically attach to and remove the gaskets from the subsea equipment.

However, such techniques suffer from a number of crucial shortcomings. For instance, such techniques are prone to damaging the sealing profile of the subsea equipment. Moreover, the relevant forces that can be exerted in such current methods are limited. One of the major problems with present methods and techniques is therefore the ineffectiveness and inability of such methods and techniques to remove stuck gaskets from the subsea equipment. In addition, the ability to control the alignment of a gasket during the installation process with current methods is also limited.

An object of the present invention is to provide a tool and method for removal and installation of a gasket from, for example, subsea equipment such as a wellhead, and particularly to provide a gasket removal and installation tool comprising features that enhance the ability and effectiveness of removing stuck gaskets from subsea equipment, particularly by incorporating features which provide the ability to apply much higher levels of force in order to remove stuck gaskets and a controlled method of level installation.

STATEMENTS OF INVENTION

According to a first aspect of the present invention there is provided a subsea tool for engaging and/or disengaging a first member that is configured to be in contact with a second member, the tool comprising: a frame configured for fitting around or on top of a peripheral surface of the first member, the frame having mounted thereon; a first engagement mechanism having one or more first engagement members configured for moving into and out of engagement with the peripheral surface of the first member; and a second engagement mechanism having one or more second engagement members for engaging the second member, the second engagement members being configured for extending and retracting relative to the frame to thereby force away from or lower against the second member; wherein the second engagement members are hydraulically driven. Such a tool affords an enhanced device for effectively releasing stuck subsea members and installing new subsea members in a controlled manner.

Optionally, the first member is a gasket, and the second member is a subsea wellhead or subsea equipment.

Optionally, a plurality of first engagement mechanisms and a plurality of second engagement mechanisms are provided on the frame.

Optionally, the frame comprises an annular body member having an inwardly facing surface profiled to be substantially congruent with an outer profile of the first member. Advantageously, such an arrangement provides embodiments of the present invention with ability to fit upon and/or around the gasket to be disengaged such that the tool can be accurately aligned prior to operation of the tool.

Optionally, the plurality of first engagement mechanisms are provided equidistantly around the annular body member. This provides for reduced stress concentration on the gasket and engagement mechanism with improved stability of gripping/clamping and/or centralising the tool on the gasket.

Optionally, the plurality of second engagement mechanisms are provided equidistantly around the annular body member. This provides for reduced stress concentration on the tool (and particularly the frame) and improved stability of lifting/displacing the tool from the wellhead.

Optionally, respective ones of the first and second engagement mechanisms are provided together adjacent one another, such that at designated locations around the annular body member a first engagement mechanism is provided adjacent a second engagement mechanism as a pair. Such an arrangement provides embodiments of the present invention which transfer forces directly through both engagement mechanisms while also allowing direct movement control at each of the first engagement mechanism locations.

Whilst any suitable number may be provided, 4 pairs of first engagement mechanisms and second engagement mechanisms may conveniently be provided, optionally substantially 90 degrees apart on the annular body member.

Optionally, the gasket has an outwardly projecting rib having an outwardly facing annular groove or flat.

In this regard, one or more first engagement members of the one or more first engagement mechanisms are conveniently configured to engage with the outwardly facing annular groove or flat.

Optionally, the one or more first engagement members of the one or more first engagement mechanisms are orientated to extend and retract in a first direction and one or more second engagement members of the one or more second engagement mechanisms are orientated to extend in a second direction, the first and second directions being substantially at 90 degrees to one another.

Optionally, the subsea tool further comprises a control means to control timing of the movement of the one or more first and second engagement members, whereby the one or more second engagement members are activated to extend, after extension of the one or more first engagement members. The operation of the one or more first and second engagement members can as such be sequenced as required.

Optionally, the one or more first and second engagement mechanisms are hydraulically driven from a common fluid source, fluid to drive the one or more second engagement mechanisms only being made available to the one or more second engagement mechanisms once the one or more first engagement mechanisms have been activated.

Optionally, the one or more first and second engagement mechanisms are hydraulically driven from a common fluid source, fluid to drive the one or more second engagement devices can be activated or controlled once the one or more first engagement mechanisms have been activated.

Optionally, the one or more first and second engagement mechanisms are hydraulically driven from a common fluid source, fluid to drive the one or more first engagement devices can be activated or controlled once the one or more second engagement mechanisms have been deactivated.

Optionally, the one or more second engagement members are configured to engage an upwardly facing surface of the second member.

According to a further aspect of the present invention, there is provided a method for disengaging a first subsea member that is in contact with a subsea second member, the method comprising:

• • (A) positioning a subsea tool as defined above such that its frame is around a peripheral surface of the first member;
  • (B) activating one or more of said first engagement mechanisms provided on the frame such that one or more engagement members engage with the peripheral surface of the first member; and
  • (C) activating one or more of said second engagement mechanisms provided on the frame such that one or more of the second engagement members are hydraulically driven to engage with the second member to urge the first subsea member out of contact with the second subsea member.

Optionally, at least one second engagement mechanism is provided proximate to and optionally directly adjacent at least one first engagement mechanism.

Optionally, each of the second engagement mechanisms are provided proximate to and optionally directly adjacent at least one first engagement mechanism such that each of the second engagement mechanisms is provided with at least one corresponding first engagement mechanism.

Optionally, the first engagement mechanism is configured to clamp on to the first member. Optionally, the first engagement mechanism is configured to increase the gripping force in tandem with the upward force of the second engagement members during the removal process.

Optionally, the first engagement members move in a first direction and the second engagement members move in a second direction, different from the first direction. Optionally, the first direction is a radial direction with respect to the central longitudinal axis of the frame.

Optionally, the second direction is a longitudinal direction parallel to the central longitudinal axis of the frame. Optionally, the first and second directions are substantially perpendicular to one another.

Optionally, the first engagement mechanism comprises a contact member having a contact surface formed thereon. The contact surface of the first engagement mechanism may be configured to engage with the first member and may more particularly be configured to engage with the outer surface of the first member. Optionally, said contact surface of the first engagement mechanism is configured to engage with the outwardly projecting rib of the first member. Optionally, said contact surface of the first engagement mechanism is configured to engage with the annular groove or flat formed on the outwardly projecting rib of the first member. Optionally, said contact surface of the first engagement mechanism is configured to engage with the inner wall portion of the annular groove or lower face formed on the outwardly projecting rib of the first member.

Optionally, the one or more first engagement mechanisms are actuatably moveable in response to fluid pressure, between a first configuration and a second configuration.

Optionally, the first and/or second engagement mechanisms each comprise hydraulic piston-cylinder arrangements.

Optionally, when the or each first engagement mechanism is in the first configuration, the contact surface of the first engagement mechanism is retracted/separated from the first member, within the annular body member and is therefore not engaged, or otherwise in contact with the first member. Optionally, when the first engagement mechanism is in the second configuration, the contact surface of the first engagement mechanism is extended towards the first member, out from the annular body member, to engage the first member.

Optionally, some or all of the first engagement mechanisms are linked so that they can be operated together. In this regard, the piston/cylinder arrangements may be linked to a common fluid source.

Optionally, the one or more second engagement mechanisms are actuatably moveable in response to fluid pressure, between a first configuration and a second configuration.

Optionally, the one or more second engagement mechanisms are configured to engage with and thereby axially lift the substantially annular body member with respect to the second member when in the second configuration.

Optionally, each second engagement mechanism comprises a contact member having a contact surface formed thereon. Optionally, said contact surface of each second engagement mechanism is configured to engage with the second member. Optionally, said contact surface of each second engagement mechanism is configured to engage with an upper surface of the second member.

Optionally, each second engagement mechanism is operated in response to fluid pressure.

Optionally, when the or each second engagement mechanism is in the first configuration, its contact surface does not extend from the face of the annular body member so as not to bias the second member. Optionally, when the or each second engagement mechanism is in the second configuration, the contact surface of the second engagement mechanism is extended towards the second member, and is engaged, or otherwise in contact with the second member.

Optionally, some or all of the second engagement mechanisms are linked so that they can be operated together.

Optionally, at least one of the second engagement mechanisms are in fluid communication with at least one of the first engagement mechanism. In this regard, they may be linked so that fluid supplied to one or more first engagement mechanisms will only be made available to the one or more second engagement mechanisms once the one or more first engagement mechanisms have been activated. This allows the one or more first engagement mechanisms and second engagement mechanisms to be activated sequentially and automatically in sequence.

According to a further aspect of the present invention there is provided method for engaging a first member into contact with a subsea second member, the method comprising:

• • a) positioning a subsea tool as defined above such that its frame is around a peripheral surface of the first member;
  • b) activating one or more of said first engagement mechanisms provided on the frame such that one or more engagement members engage with the peripheral surface of the first member to hold it for transport thereof;
  • c) activating one or more of said second engagement mechanisms provided on the frame such that one or more of the second engagement members hydraulically extend to be proud of the first member;
  • d) transporting the tool so as to be positioned above the second member;
  • e) lowering the tool so that the second engagement members land on the second member;
  • e) activating the one or more second engagement mechanisms to retract the second engagement members, thereby lowering the first member onto the second member;
  • f) activating the one or more first engagement mechanisms to retract the first engagement members to release the first member from the tool and in position on the second member.

Optionally, steps a), b) and c) are carried out before the tool is subsea.

Optionally, the subsea tool comprises at least one downwardly depending guide arm for guiding the tool into position with respect to the second member and/or the first member. Optionally, said at least one guide arm is configured to centre and/or align the tool with respect to the second member and/or the first member.

Optionally, said at least one guide arm extends from the annular body member.

Optionally, said at least one arm extends downwardly from the tool in a direction substantially parallel to the central longitudinal axis of the substantially annular body member.

The tool may comprise a plurality of guide arms arranged in a circular array around the substantially annular body member. Optionally, the plurality of guide arms are each arranged equidistantly from one another such that each of the adjacent arms are positioned at an equal distance from one another.

Optionally, said frame comprises at least one frame arm extending upwardly from the substantially annular body member.

Optionally, the at least one frame arm is securely connected to the substantially annular body member. The at least one frame arm may be welded or securely connected by a bolt or screw, or other suitable fixing arrangement.

Optionally, said frame comprises a plurality of frame arms extending upwardly from the substantially annular body member. The frame arms may be inclined inwardly along their length to meet at a central point above the annular body member.

Optionally, the tool comprises at least one connecting mechanism for coupling the tool to a tether, such as a rope or chain. Optionally, the frame comprises said at least one connecting mechanism, in the form of a ring, hook or similar structure.

Optionally, the tool comprises at least one connecting mechanism for coupling to an ROV by means of a number of different types of ROV handles or similar.

Optionally, the pressurised fluid is pumped from a Remotely Operated Vehicle (ROV) comprising a pressurised pumping arrangement.

Optionally, the said fluid is pumped from a vessel. Typically, said fluid pumped from a vessel is pumped via at least one umbilical pipe, preferably by a pumping mechanism where said pumping arrangement is typically located on or is otherwise associated with or used in conjunction with the vessel such as a Remotely Operated Vehicle (ROV).

Optionally, the fluid is pumped from a pump located at the surface on a rig or vessel.

Optionally, the method comprises simultaneously activating a plurality of said first engagement mechanisms provided on the substantially annular body member to engage with the first member.

Optionally, the method comprises independently and successively activating each of a plurality of said first engagement mechanism provided on the substantially annular body member to engage with the first member.

The accompanying drawings illustrate presently exemplary embodiments of the disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain, by way of example, the principles of the disclosure.

In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention is susceptible to embodiments of different forms. Specific embodiments of the present invention are shown in the drawings, and herein will be described in detail, with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.

The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one embodiment can typically be combined alone or together with other features in different embodiments of the invention. Additionally, any feature disclosed in the specification can be combined alone or collectively with other features in the specification to form an invention.

Various embodiments and aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary embodiments and aspects and implementations. The invention is also capable of other and different embodiments and aspects, and its several details can be modified in various respects, all without departing from the scope of the present invention.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising”, it is understood that we also contemplate the same composition, element or group of elements with transitional phrases “consisting essentially of”, “consisting of”, “selected from the group of consisting of”, “including”, or “is” preceding the recitation of the composition, element or group of elements and vice versa. In this disclosure, the words “typically” or “optionally” are to be understood as being intended to indicate optional or nonessential features of the invention which are present in certain examples, but which can be omitted in others without departing from the scope of the invention.

All numerical values in this disclosure are understood as being modified by “about”. All singular forms of elements, or any other components described herein including (without limitations) components of the apparatus described herein are understood to include plural forms thereof and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, of which:

FIG. 1 shows a perspective view of an exemplary subsea tool in accordance with the present invention;

FIG. 2 is a side part cross-sectional view of the subsea tool shown in FIG. 1, but the tool is shown positioned around a gasket that is in contact with a wellhead;

FIG. 3 is a detailed view of the subsea tool shown in FIG. 2, showing the contact between the gasket and the subsea wellhead;

FIG. 4 is a perspective schematic view of a substantially annular body member of the subsea tool, showing the position and arrangement of the first and second engagement members positioned within the substantially annular body member;

FIG. 5 is a detailed view of a set of adjacent first and second engagement members of the substantially annular body member of FIG. 4, with the first and second engagement members in the extended configuration;

FIG. 6 is a detailed view of a set of the adjacent first and second engagement members of the substantially annular body member of FIG. 4, with the first and second engagement members in the retracted configuration;

FIG. 7 is a cross-sectional view of the substantially annular body member, showing the second engagement member in the extended configuration;

FIG. 8 is a cross-sectional view of the substantially annular body member, showing the first engagement member in the extended configuration;

FIG. 9 is a cross-sectional view of the subsea tool, showing the first engagement member in the retracted configuration;

FIG. 10 is a cross-sectional view of the subsea tool, showing the second engagement member in the retracted configuration;

FIG. 11 is a front view of the subsea tool of FIG. 1, but the tool is shown positioned around a gasket that is in contact with a wellhead, and is also shown with an exemplary fluid conduit arrangement;

FIG. 12 is a plan view of the subsea tool and exemplary fluid conduit arrangement shown in FIG. 11;

FIG. 13 is a perspective view of the subsea tool and exemplary fluid conduit arrangement shown in FIGS. 11 and 12;

FIG. 14 is a further perspective view of the subsea tool and exemplary fluid conduit arrangement shown in FIGS. 11 and 12.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings, FIG. 1 shows a subsea tool 1 used for engaging and/or disengaging a first member such as a gasket 10 that is configured to be in contact with a second member such as a well head 20 (as best shown in FIGS. 2 and 3). The tool 1 comprises a frame 30 configured for fitting around a peripheral surface of the gasket 10, the frame 30 having mounted thereon one or more first engagement mechanisms 40 as shown in FIGS. 4 and 5, having one or more first engagement members 41 configured for moving into and out of engagement with the peripheral surface of the gasket 10.

The tool 1 further has one or more second engagement mechanisms 50 having one or more second engagement members 51 configured for moving into an out of engagement with the second member 20. At least the one or more second engagement members 51 are hydraulically driven (as will be described subsequently).

As shown in FIG. 9, the gasket 10 is a ring gasket, and may have an outwardly projecting rib 11. The ring gasket 10 may have an annular groove 12 formed around an outer surface of the gasket 10. This groove 12 may comprise an inner wall portion 13. The gasket 10 shown comprises a VX type rib. Examples of suitable gaskets include the VX Type and VGX Type available from Sub-drill but other suitable gaskets could also be used.

As shown in FIG. 4, the frame 30 includes, at a base area, a substantially annular body member 31, which in a disengagement mode is configured to be provided around the gasket 10 installed in the well head 20. The specific dimensions of the substantially annular body member 31 can vary with regard to the specific dimensions of the wellhead 20 and the associated gasket 10. In this connection, the substantially annular body member 31 has an inwardly facing surface that is adapted to be at least partially congruent with the outwardly facing surface of the wellhead 20.

The first engagement mechanism 40 is operable to move between a first configuration and a second configuration. FIGS. 6 and 9 show the first engagement mechanism 40 in said first configuration. When the first engagement mechanism 40 is in said first configuration, the first engagement mechanism 40 is typically retracted away from the gasket 10. FIG. 5 shows the first engagement mechanism 40 in the second configuration. When the first engagement mechanism 40 is in said second configuration, the first engagement mechanism 40 is typically extended towards and in engagement with the gasket 10. The first engagement mechanism 40 may be configured to clamp on to the first member 10 when in the second configuration. The first engagement mechanism 40 may moreover be configured to grip or hold the first member 10 (as will be described subsequently) when in the second configuration.

The first engagement mechanism 40 comprises a contact member 41 having a contact surface 42 formed thereon. The contact surface 42 of the first engagement mechanism 40 may be configured to engage with the outer surface of the first member 10 (and/or the inner wall portion 13 of the annular groove 12 formed on the outwardly projecting rib 11 of the first member 10).

The first engagement mechanism 40 can be actuatably moveable in response to fluid pressure, and specifically the first engagement mechanism 40 may be actuatably moveable between said first configuration and second configuration in response to said fluid pressure.

As shown in FIG. 8, the first engagement mechanism 40 comprises a housing, having a cylinder 43 provided therein, defining a fluid chamber 44. The first engagement mechanism 40 further comprises a fluid activated piston 45 which is provided within the cylinder 43/fluid chamber 44 of the first engagement mechanism 40. The chamber 44 of the first engagement mechanism 40 is defined by at least one inner surface of the cylinder 43 of the first engagement mechanism 40 and an innermost face of the piston 45 of the first engagement mechanism 40. The piston 45 of the first engagement mechanism 40 is adapted to move back and forth within the cylinder 43 of the first engagement mechanism 40 in response to the modification of fluid pressure in the chamber 44 of the first engagement mechanism 40. The piston 45 of the first engagement mechanism 40 comprises (and/or is connected to or directly connected to) the contact member 41 of the first engagement mechanism 40 such that as the piston 45 of the first engagement mechanism 40 is moved back and forth within the cylinder 43 of the first engagement mechanism 40 (e.g. in response to the modification of fluid pressure in the chamber 44 of the first engagement mechanism 40), the contact member 41 (and the contact surface 42 formed thereon) correspondingly moves back and forth.

When the first engagement mechanism 40 is in the first configuration, the contact surface 42 of the first engagement mechanism 40 is retracted/separated from the first member 10, and is therefore not engaged, or otherwise in contact with the first member 10 (as shown in FIG. 9). On the other hand, when the first engagement mechanism 40 is in the second configuration, the contact surface of the first engagement mechanism 40 is extended towards the first member 10, and is engaged, or otherwise in contact with the first member 10 (as shown in FIG. 8).

The first engagement mechanism 40 comprises at least one fluid port 46 (as best shown in FIG. 12) provided proximate to the fluid chamber 44 of the first engagement mechanism 40. The fluid port 46 of the first engagement mechanism 40 is operable to permit fluid into the fluid chamber 44 of the first engagement mechanism 40. The piston 45 of the first engagement mechanism 40 is radially moveable from the first (i.e. retracted) configuration to the second (i.e. extended) configuration by introduction of fluid through said fluid port 46 of the first engagement mechanism 40 into the fluid chamber 44 of the first engagement mechanism 40. The fluid port 46 of the first engagement mechanism 40 may also be operable to permit fluid out of the fluid chamber 44 of the first engagement mechanism 40. The piston 45 of the first engagement mechanism 40 may be radially moveable from the second (i.e. extended) configuration to the first (i.e. retracted) configuration by withdrawal of fluid through the fluid port 46 of the first engagement mechanism 40 from the fluid chamber 44 of the first engagement mechanism 40.

When the piston 45 of the first engagement mechanism 40 is in the first configuration a face (i.e. contact surface 42) of the piston 45 of the first engagement mechanism 40 is retracted from, and not engaged with, the first member. On the other hand, when the piston 45 of the first engagement mechanism 40 is the second configuration a face (i.e. contact surface 42) of the piston 45 of the first engagement mechanism 40 is extended, and engaged with, the first member 10.

At least one first engagement mechanism 40 may be in fluid communication with at least one other first engagement mechanism 40. Typically, said at least one first engagement mechanism 40 is in fluid communication with at least one other first engagement mechanism 40 via a conduit 70 in fluid communication between the respective fluid ports 46 of each of said first engagement mechanisms 40. Advantageously, when the first engagement mechanisms 40 are in fluid communication with one another (e.g. via the respective fluid ports 46), said first engagement mechanisms 40 are operable to radially move simultaneously.

Each second engagement mechanism 50 is operable to move between a first configuration and a second configuration. FIGS. 6 and 10 show the second engagement mechanism 50 in said first configuration. When each second engagement mechanism 50 is in said first configuration, it is typically retracted so as not to extend out of the annular body member and away from the subsea wellhead 20, such that said second configuration defines a disengaged configuration between the subsea wellhead 20 and the second engagement mechanism 50. FIG. 7 shows a second engagement mechanism 50 in the second configuration. When the second engagement mechanism 50 is in said second configuration, the second engagement mechanism 50 is typically extended towards and into engagement with the subsea wellhead 20. The second engagement mechanism 50 is configured to contact and push against the first member 20 (subsea wellhead 20) when in the second configuration such that the second engagement mechanism 50 is configured to engage with and thereby axially lift the substantially annular body member 31 with respect to the subsea wellhead 20 when in the second configuration. As such, the subsea tool has been used to disengage the gasket 10 from the wellhead 20.

Each second engagement mechanism 50 comprises a contact member 51 having a contact surface 52 formed thereon. The contact surface 52 of the second engagement mechanism 50 may be configured to engage with an upper surface of the second member 20 (subsea wellhead 20).

Each second engagement mechanism 50 can be actuatably moveable in response to fluid pressure, and specifically each second engagement mechanism 50 may be actuatably moveable between said first configuration and second configuration in response to said fluid pressure.

As shown in FIG. 7, each second engagement mechanism 50 comprises a housing 53, having a cylinder 53 provided therein, defining a fluid chamber 54. Each second engagement mechanism 50 further comprises a fluid activated piston 55 which is provided within the cylinder 53/fluid chamber 54 of the second engagement mechanism 50. The chamber 54 of the second engagement mechanism 50 is defined by at least one inner surface of the cylinder 53 of the second engagement mechanism 50 and an innermost face of the piston 55 of the second engagement mechanism 50. The piston 55 of the second engagement mechanism 50 is adapted to move back and forth within the cylinder 53 of the second engagement mechanism 50 in response to the modification of fluid pressure in the chamber 54 of the second engagement mechanism 50. The piston 55 of the second engagement mechanism 50 comprises (and/or is connected to or directly connected to) the contact member 51 of the second engagement mechanism 50 such that as the piston 55 of the second engagement mechanism 50 is moved back and forth within the cylinder 53 of the second engagement mechanism 50 (e.g. in response to the modification of fluid pressure in the chamber 54 of the second engagement mechanism 50), the contact member 51 (and the contact surface 52 formed thereon) correspondingly moves back and forth.

When each second engagement mechanism 50 is in the first configuration, the contact surface 52 is retracted within the annular body member of the frame so that it does not bias against the second member 20 (e.g. subsea wellhead 20), (as best shown in FIG. 10). On the other hand, when each second engagement mechanism 50 is in the second configuration, the contact surface 52 of the second engagement mechanism 50 is extended towards the second member 20, and is engaged, or otherwise in contact with the second member 20 (as shown in FIG. 7). In this way the annular body member is urged away from the wellhead, taking the gasket with it.

Each second engagement mechanism 50 comprises at least one fluid port 56 provided proximate to the fluid chamber 54 of the second engagement mechanism 50. The fluid port 56 is operable to permit fluid into the fluid chamber 54. The piston 55 of the second engagement mechanism 50 is axially moveable from the first (i.e. retracted) configuration to the second (i.e. extended) configuration by introduction of fluid through said fluid port 56 of the second engagement mechanism 50 into the fluid chamber 54 of the second engagement mechanism 50. The fluid port 56 may also be operable to permit fluid out of the fluid chamber 54. The piston 55 may be axially moveable from the second (i.e. extended) configuration to the first (i.e. retracted) configuration by withdrawal of fluid through the fluid port 56 from the fluid chamber 54.

When the piston 55 of each second engagement mechanism 50 is in the first configuration a face (i.e. contact surface 52) of the piston 55 is retracted from, and not engaged with, the second member 20 (e.g. subsea wellhead 20). On the other hand, when the piston 55 of the second engagement mechanism 50 is the second configuration a face (i.e. contact surface 52) of the piston 50 is extended, and engaged with, the second member 20.

At least one second engagement mechanism 50 may be in fluid communication with at least one other second engagement mechanism 50. Typically, said at least one second engagement mechanism 50 is in fluid communication with at least one other second engagement mechanism 50 via a conduit 70 in fluid communication between the respective fluid ports 56 of each of said second engagement mechanisms 50. Advantageously, when the second engagement mechanisms 50 are in fluid communication with one another (e.g. via the respective fluid ports 56), said second engagement mechanisms 50 are operable to axially move simultaneously.

As shown, each of the second engagement mechanisms 50 are provided proximate to and directly adjacent to at least one first engagement mechanism 40 such that each of the second engagement mechanisms 50 is provided with at least one corresponding first engagement mechanism 40.

At least one second engagement mechanism 50 may be in fluid communication with at least one first engagement mechanism 40. Typically, said at least one first engagement mechanism 40 is in fluid communication with at least one second engagement mechanism 50 via a conduit 70 in fluid communication between the respective fluid ports 46, 56 of each of said first and second engagement mechanisms 40, 50. Advantageously, when the first and second engagement mechanisms 40, 50 are in fluid communication with one another (e.g. via the respective fluid ports 46, 56), said first and second engagement mechanisms 40, 50 are operable to move sequentially.

The above description describes primarily how the tool is used to disengage for example a gasket from a wellhead. However, the tool can equally be used to perform an engagement or installation operation.

In this respect, the tool is capable of automated gasket installation when the operations are is essence run in reverse to those described above. This is achieved by the first and second engagement mechanisms being activated for example on the rig or vessel with the tool lowered over the top of the gasket, the first engagement mechanism engages with the gasket and makes contact with the gasket recess or rib once this process has taken place, the second engagement mechanism is activated allowing the second engagement members to extend so that they are extended from the frame. The gasket is as such installed in the tool ready to be run down to the subsea wellhead or subsea equipment via an ROV or rig/vessel winch or similar.

As the next stage, the tool is lowered into the sea and landed onto the subsea wellhead or subsea equipment. The second engagement members are then activated to retract, thereby lowering the gasket into the seal profile in a controlled fashion. Once the second engagement members have retracted, the first engagement members are activated to disengage from the gasket leaving it in the seal profile of the wellhead. The tool is then lifted away, leaving the gasket installed level in the subsea wellhead or subsea equipment. This method provides an automated means of installing the gasket in the subsea wellhead or subsea equipment by ROV means or Rig/Vessel crane or winch with visual ROV assistance.

In this connection, the tool further comprises a plurality of guide arms 60 extending downwardly from the substantially annular body member 31 in a direction substantially parallel to the central longitudinal axis of the substantially annular body member 31. The guide arms 60 are configured to guide the tool 1 into position with respect to the second member 20 when in relatively close proximity thereto and are also configured to centre and/or align the tool 1 with respect to the second member 20 and/or the first member 10. The arms 60 can be securely connected to the tool 1 by welding, by bolts or screws (not shown), or other suitable mating arrangements. The plurality of arms 60 are arranged in a circular array around the substantially annular body member 31 and are each arranged equidistantly from one another such that each of the adjacent arms 60 are positioned at an equal distance from one another. The arms 60 are operable to radially secure, lock, or at least loosely hold in place, the tool 1 with respect to the second member 20 and/or the first member 10. However, particularly during operation of the second engagement mechanisms 50 during removal operations, it is generally preferred that the arms 60 do not lock the longitudinal movement of the tool 1 (and therefore the substantially annular body member 31) with the respect to the second member 20, such that the arms 60 do not impede operation of the second engagement mechanism 50. The skilled person will however understand that in certain embodiments it may be desirable for the tool 1 to be locked, or at least partially held, at a specific longitudinal position with the respect to the first member 10 or second member 20 prior to and/or during operation of the first engagement mechanism 40. Therefore, the arms 60 may be operable to lock the longitudinal movement of the tool 1 (and therefore the substantially annular body member 31) with respect to the second member 20 during operation of the first engagement mechanism 40. In this way, the tool 1 may be longitudinally locked (with respect to the second member 20) when the correct / optimal longitudinal positioning of the tool 1 is achieved, enabling the first engagement mechanism 40 to contact/engage with the first member 10 at any preferred longitudinal position. The arms 60 may have an inner contact surface that is substantially congruent with the outer surface of the second member 20.

Advantageously, when at least two arms 60 are provided, the arms 60 are operable to at least partially radially secure (lock, or at least loosely hold in place) the tool 1 with respect to the second member 20 and/or the first member 10 in at least one radial direction. Even more advantageously, when at least three arms 60 are provided, the arms 60 are operable to at least partially radially secure (lock, or at least loosely hold in place) the tool 1 with respect to the second member 20 and/or the first member 10 in substantially all radial directions.

The frame 30 further comprises a plurality of frame arms 32 extending upwardly from the substantially annular body member 31. Each respective frame arm 32 comprises a first end and a second opposite end. Each frame arm 32 is securely connected to the tool 1 by welding, by a bolt or screw (not shown), or other suitable mating arrangement. The first end of each frame arm 32 is connected to the substantially annular body member 31, and the second end of each frame arm 32 is connected to the second end of at least one other frame arm 32. Each of the first ends of the plurality of frame arms 32 are connected to the substantially annular body member 31 such that the first ends of the frame arms 32 are arranged in a circular array around the substantially annular body member 31. The first ends of the plurality of frame arms 32 are each arranged equidistantly from one another such that each of the adjacent first ends of the frame arms 32 are positioned at an equal distance from one another.

As shown in FIGS. 1 and 2, the tool 1 further comprises at least one connecting mechanism 33 for coupling the tool 1 to a tether, such as a rope or chain (not shown). Typically, the frame 30 comprises said at least one connecting mechanism 33 and said at least one connecting mechanism 33 is typically provided relative to the or each of the second ends of the at least one frame arms 32 (as best shown in FIG. 12). The at least one connecting mechanism 33 may comprise a chain connector ring, shackle, hook or directly to an ROV by means of a handle. Typically, the said connecting mechanism 33 is configured for supporting and directing the tool 1 to a predetermined location on a seabed. (i.e. proximate to the subsea wellhead and gasket thereon).

The pressurised fluid may be pumped from a Remotely Operated Vehicle (ROV) (not shown) comprising a pressurised pumping arrangement. The fluid pumped from said Remotely Operated Vehicle (ROV) may be hydraulic fluid or seawater. Alternatively, said fluid may be pumped from a vessel (not shown). Typically, when said fluid is pumped from a vessel, said fluid is pumped via at least one umbilical pipe, by a pumping mechanism where said pumping arrangement is typically located on or is otherwise associated with or used in conjunction with the vessel, such as a Remotely Operated Vehicle (ROV). Typically, the umbilical pipes are provided with two ends, one end of each coupled to the vessel or ROV as appropriate and the other ends coupled to the tool 1. The tool 1 comprises at least one fluid inlet 71 and one fluid outlet 72. The fluid inlet 71 and outlet 72 are provided on the frame 30 and the said other end of the umbilical pipes is connected to at least one fluid inlet 46 and at least one fluid outlet 56. The skilled person will however understand that any suitable form and/or source of pressurised fluid may be used.

The tool 1 comprises at least one conduit 70 for conveying pressurised fluid between the fluid inlet 71 to the respective first and second engagement mechanism(s) 40, 50. Said conduit 70 may be in the form of flexible tube or pipe. As shown in FIGS. 11-14, said at least one conduit 70 is provided wholly externally to the substantially annular body member 31, with connections provided to each of the respective fluid ports 46, 56 of the first and second engagement mechanisms 40, 50. Alternatively, although not shown, said at least one conduit 70 may be at least partially formed internally within (and/or at least partially contained within) the frame 30 or the substantially annular body member 31.

As the skilled person will appreciate, an operator of the tool 1 may prefer to operate the first engagement mechanisms 40 independently from the second engagement mechanisms 50. Accordingly, the at least one conduit 70 may comprise a first conduit 70a, and a second conduit 70b independent of (i.e. not in fluid communication with) said first conduit 70a. As shown in FIG. 11-14, the first conduit 70a is in fluid communication with each of the fluid ports 46 of each first engagement mechanisms 40, whereas the second conduit 70b is in fluid communication with each of the fluid ports 56 of each second engagement mechanisms 50. Advantageously, such an arrangement enables the operator to selectively operate the first engagement mechanisms 40 independently from the second engagement mechanisms 50 such as during removal of the gasket 10 from the wellhead 20 whereby the operator can, for instance, first operate the first engagement mechanisms 40 (i.e. to grip on to the first member/gasket 10) and then subsequently operate the second engagement mechanisms 50 (i.e. to engage with and thereby axially lift the substantially annular body member 31 with respect to the second member/wellhead 20).

Modifications and improvements may be made to the hereinbefore described embodiments without departing from the scope of protection.