WO2018233783A1

WO2018233783A1 - Method and apparatus for deploying/retrieving tubing string from offshore rig

Info

Publication number: WO2018233783A1
Application number: PCT/DK2018/000018
Authority: WO
Inventors: Nikolai GOLOVINSKIJ
Original assignee: Maersk Drilling A/S
Priority date: 2017-06-19
Filing date: 2018-06-19
Publication date: 2018-12-27
Also published as: GB2577424A; DK179933B1; GB2577424B; NO20191470A1; GB201917953D0; DK201700361A1

Abstract

A method for deploying a tubular string from an offshore rig (10) comprising a hull (12) and a cantilever (20), wherein the cantilever (20) defines a well centre (28) and is configured to support a tubular string (51) and is extendable over a side of the hull (12), the method comprising: providing a support structure (30) separated from the well centre (28); assembling multiple components to form a tubular string (51) suspended from the support structure (30), wherein the tubular string (51) is off-set from the well centre of the cantilever (20); and aligning the tubular string (51) with the well centre (28) of the cantilever (20).

Description

METHOD AND APPARATUS FOR DEPLOYING/RETRIEVING TUBING STRING

FROM OFFSHORE RIG

FIELD

The present disclosure relates to a method and apparatus for performing offshore operations, including deploying and/or retrieving a tubing string from an offshore rig. BACKGROUND

In the offshore oil and gas industry well operations are performed from specialised platforms or vessels, known colloquially as "rigs". Multiple types of rig exist, such as fixed platforms, jack-ups, semi-submersibles, ships, barges and the like. The particular type of rig used can depend on a number of factors, such as water depth, rig availability, expected longevity of the associated reservoir, operational requirements and the like. Offshore rigs typically define a well centre, wherein operations, such as drilling, deploying/retrieving equipment and the like, are performed along the well centre. The well centre therefore defines a critical work path, and many operations which require the facilities provided on the well centre, such as a derrick hoisting system, must necessarily be performed after the preceding operation has been completed. Such sequential performance of operations may therefore dictate the required rig time, and thus associated rig costs.

SUMMARY

According to the disclosure is a method for deploying a tubular string from an offshore rig comprising a hull and a cantilever, wherein the cantilever defines a well centre, is configured to support a tubular string and is extendable over a side of the hull, the method comprising:

providing a support structure separated from the well centre;

assembling multiple components to form a tubular string suspended from the support structure, wherein the tubular string is off-set from the well centre of the cantilever; and

aligning the tubular string with the well centre of the cantilever.

Accordingly, the tubular string may be assembled at a location which is off-set from the well centre, and thus without occupying the well centre, saving operational time on this critical work path. While the tubular string is being assembled, other operations, such as drilling operations, assembling equipment, deploying equipment and the like, may be performed on the well centre. This may assist to reduce necessary rig time. Whenever operations require use of the assembled tubular string, said string may be aligned with the well centre. Extending the tubular string into the body of water during assembly may permit extended lengths of tubular string to be formed. The ability to extend the tubular string into the body of water from the support structure may avoid limitations which might otherwise exist in relation to the available lifting height of lifting or hoisting equipment provided on the rig, the rig storage capacity and the like. This may allow tubular strings to be prepared for use which are of a length otherwise typically not permitted on an offshore rig, unless formed on the well centre. For example, while rigs may accommodate pre- assembled stands of tubulars, such as pre-connected lengths of riser, conductor pipe, casing and the like, these are typically restricted to the lifting height of the rig's hoisting equipment and/or the capacity of the storage bay. In some examples, the length of pre- assembled tubular stands provided on a rig may be limited to, for example, between 25 and 30 meters. In the present method, a tubular string may be assembled which significantly exceeds this otherwise restricted length, for example restricted only by the depth of the body of water.

The method may comprise assembling multiple tubular components together to define or form the tubular string. The method may comprise assembling individual lengths of tubular together. The method may comprise assembling together multiple stands of tubulars together, wherein each stand comprises two or more pre-assembled tubulars. The tubular string (for example assembled from multiple components) may be suspended from the support structure and/or cantilever to extend below a deck of the rig, the hull and/or into a body of water. The method may comprise assembling multiple components to form a tubular string which extends below a deck of the rig, the hull and/or into a body of water. Multiple components may be assembled to form a tubular string which extends below a deck of the rig, the hull and/or into a body of water. The tubular string may be moved between the cantilever and support structure while extending below a deck of the rig, the hull and/or into a body of water.

Individual components may be secured together by any desired method, such as threaded connection, quick-connector type connection, and the like. The method may comprise securing individual components together on or at the level of the support structure. The support structure may include or support appropriate equipment for use in securing individual components together, such as threading tongs, spiders (e.g., a riser spider) and the like.

The tubular string may comprise any form of tubular string for use in supporting well operations, including drilling operations, well casing operations, completion operations, intervention operations and/or the like. The tubular string may comprise a drill string, completion or production string.

In some examples, the tubular string may be provided to extend between subsea equipment and the rig. The tubular string may be provided to extend part of way between subsea equipment and the rig. The subsea equipment may comprise, for example, a wellhead, a Xmas tree, a BOP and the like. The subsea equipment may be a subsea well centre. The tubular string may define a riser, such as a high pressure riser. The tubular string may define a drilling riser. In such an example the tubular string may be formed by connecting together multiple riser joints. Each rise joint may comprise at least a primary tubular structure. Each riser joint may comprise one or more secondary tubular structures externally of the primary tubular structure.

The tubular string may comprise a conductor. A lower end of said conductor may extend below a seabed, and an upper end may extend above the body of water.

The tubular string may be provided to extend below the seabed, for example into a wellbore. In such an example the method may comprise extending the tubular string into the wellbore from the cantilever and along the well centre. The tubular string may define a casing string, conductor, riser, liner string or the like.

The method may comprise completely assembling the tubular string prior to aligning with the well centre. In such an arrangement the tubular string may be ready for immediate use following alignment with the well centre. Alternatively, the method may comprise partially assembling the tubular string prior to aligning with the well centre, and subsequently completing the assembly while aligned on the well centre. For example, upper components of the tubular string, such as tension joints, diverters and the like may be assembled once aligned with the well centre. In some examples an upper end of the tubular string may be secured to a BOP stack provided on or in the cantilever. Completion of the assembly may be supported by or from the cantilever.

The method may comprise supporting the tubular string from the cantilever once said tubular string is aligned with the well centre. The method may comprise transferring support from the support structure to the cantilever. The method may comprise securing the tubular string to a lifting system of the cantilever once said tubular string is aligned with the well centre.

The method may comprise assembling components and progressively extending the length of the tubular string into the body of water. The method may comprise assembling components to progressively extend the tubular string to a required length. The required length may be longer than a derrick on the rig (e.g. arranged to support a tubular string component. When at the required length the tubular string may extend to a desired depth within the body of water. In some examples the tubular string may be assembled such that a lower end is located in proximity to a subsea well centre. In some examples the tubular string may be assembled such that a lower end is located in proximity to subsea equipment, such as a wellhead, Xmas tree, BOP or the like. In such an example the tubular string may be coupled to subsea equipment before or after being aligned with the well centre. The method may comprise installing suitable equipment at the lower end of the tubular string to facilitate connection with subsea equipment. Such equipment may be the first equipment assembled during the forming of the tubular string. Such equipment may include, for example, a connector, a connector landing frame and the like. In some examples other equipment may include stress joints and the like.

The method may comprise providing a tubular support apparatus on the support structure. The tubular support apparatus may function to support the tubular string during and after its assembly. For example, the tubular support apparatus may comprise slips. The slips may support the tubular string when a new tubular string component is added. The slips may open as the new tubular string is lowered. The slips may then close again after the tubular string has been lowered. That is, the tubular string may be at least partially suspended from the tubular support apparatus. The method may therefore comprise supporting the tubular string from the support apparatus provided on the support structure.

The tubular support apparatus may be an integral part of the support structure. Alternatively, the tubular support apparatus may be provided separately from the support structure and mounted thereon.

The tubular support apparatus may provide functionality to connect together components of the tubular string. As such, the method may comprise securing together adjacent components of the tubular string using the tubular support apparatus.

The tubular support apparatus may comprise a spider, such as a riser spider. The tubular support apparatus may comprise a slip apparatus.

The method may comprise raising the tubular string to cantilever. The method may comprise raising the assembled tubular string to the cantilever. The method may comprise raising the tubular string to the deck region of the cantilever. The method may comprise lowering the tubular string from the deck region of the cantilever (e.g. to the support structure). The method may comprise the support structure raising and/or lowering the tubular string relative to the support structure. The tubular string may be lowered after support of the tubular member is transferred from the cantilever to the support structure. The tubular string may be lifted before support of the tubular member is transferred from the support structure to the cantilever.

The support structure and/or tubular support apparatus may be configured to raise and/or lower the tubular string or individual components thereof relative to the support structure and/or tubular support. The support structure and/or tubular support apparatus may comprise a lifting device configured to raise/lower the tubular string or individual components thereof relative to the support structure and/or tubular support. The lifting device may comprise a winch, hoist and/or dolly arranged to provide vertical travel to the tubular structure or an individual component thereof. The lifting device may comprise a riser handling tool or a riser running tool.

Multiple individual components may be provided in a storage position, for example on the rig and/or on a separate service rig or vessel. In some examples multiple individual components may be stored on or above a main deck of the rig. Individual components may be stored within a storage bay, such as a tubular storage bay, for example a riser storage bay.

The method may comprise moving individual components from a storage position to be presented for assembly, for example presented for connection to a prior assembled component. The rig may comprise a transfer arrangement for transferring a component to be presented for assembly. In some examples the transfer arrangement may comprise a deck crane which may be utilised to transfer individual components to be presented for assembly. The transfer arrangement may comprise one or more winches or the like.

In some examples the support structure may be positioned or positionable so as to be within an operational envelope of a transfer arrangement, such as a deck crane.

The method may comprise stabilising an individual component during connection with another component. For example, the method may comprise stabilising an upper region of an individual component during connection to another component. The method may comprise stabilising a middle or lower region of an individual component - for example during connection to another component. A stabilising guide may be provided on the rig. In some examples the stabilising guide may be provided on the support structure. The stabilising guide may be provided separately from the support structure, for example extending from a deck, such as a main deck, of the rig.

The rig may comprise any form of rig or vessel but is typically a jack-up drilling rig. For a jack-up rig, the rig comprises a plurality of legs arranged to be extended downwardly from the hull to engage the seabed and lift the hull above the surface of the body of water. For a drilling rig, the cantilever is a drilling cantilever extendable over a side of the hull.

In some examples the cantilever and/or the support structure may extend outwardly, away from a rig centre. In alternative examples the cantilever and/or the support structure may extend over a moon-pool region of the rig.

The cantilever may be extendable from an outer side of the hull

The support structure may be arranged on an outer side of the hull

The cantilever may be extendable and retractable (e.g. at least partially extendable and/or retractable) over a side of the hull.

The method may comprise supporting the tubular string from the cantilever. The cantilever may be for supporting a tubular string. The cantilever may be configured to support the tubular string. The cantilever may comprise a tubular support apparatus to support the tubular string before, during and/or after assembly of the string.

The method may comprise hoisting the tubular string once support of the tubular string has been transferred to the cantilever. The cantilever may comprise or support a lifting system e.g. a hoisting system - for example for any of lifting, lowering and/or supporting the tubular string.

The cantilever of the present invention may also be referred to as a drilling cantilever. Such a cantilever comprises a deck region or floor which an an operations floor or drill floor. The deck region defines a well center defined by an opening on the deck, equipment and/or structure for supporting a tubular string, such as drill string or casing string, by the deck e.g. via slips. The well center is further defined by the cantilever supporting the hoisting system for raising or lowering the tubular string to and into the drill floor. The hoisting system is often a block and tackle system supported by a derrick and where hoisting and braking is provided by a drawworks. The deck region may be for assembling and/or disassembling the tubular string. The tubular string may be assembled or disassembled at the deck region (e.g. tubular components may be connected to or disconnected from the tubular string). Typically, the drill floor support machines for making up and/or braking out tubular components from the string such as an iron rough neck well known in the art.

The apparatus or rig may provide a plurality of support structures, for example two, three, four or more than four. Each support structure may be in accordance with a support structure as described herein.

The support structure may comprise a deck region. The deck region may provide a support surface, for example for the support and/or storage of equipment, components and the like. The deck region may permit personnel access.

The support structure may permit downward passage of the tubular string and/or individual components therethrough. The support structure may define an aperture therein to facilitate passage of the tubular string. In some examples the support structure may include multiple components arranged side-by-side, with a lateral separation gap therebetween to permit passage of the tubular string. In some examples a support apparatus for supporting the tubular string may extend between separate components of the support structure.

The support structure may be separated from the well centre. The support structure may be separate from the cantilever. The support structure may be independently movable with respect to the cantilever. The method may comprise providing a support structure separate from the well centre, the support structure may subsequently be moved to the well centre - for example to align the tubular string with well centre of the cantilever.

The support structure may be provided on the same side of the hull and the cantilever. As such, the support structure may be laterally off-set from the well centre of the cantilever in the direction of the side of the hull.

The support structure may extend from a side of the hull. The support structure may be permanently extended over the side of the hull. Alternatively, the support structure may be extendable and retractable over the side of the hull.

The method may further comprise supporting or suspending the tubular string below the level of the cantilever. The tubular string may be suspended from the support structure below the level of the cantilever (or the specified arrangement). The tubular string may be suspended from the support structure below the level of the deck region of the cantilever. The uppermost end of the tubular string may be below the level of the cantilever. A point or the points at which the tubular string is supported by the supporting structure may be below the level of the cantilever (or the specified arrangement) The method may comprise the supporting or suspending structure supporting the tubular string below the level of the cantilever. Below the level of the cantilever may be below a horizontal plane in which the cantilever lies. The support structure may be arranged to support or suspend a tubular string at a height lower than that of the cantilever, or a deck/floor of the cantilever. The support structure may be arranged to support or suspendi a tubular string below the cantilever, the level of the cantilever, a drill floor of the cantilever and/or a deck surface of the rig.

The tubular string may be assembled, then lowered to below one of the levels described above. The tubular string may then be raised to, or above, one of the levels described above.

The support structure may be positioned or positionable below the cantilever. The support structure may be positioned or positionable below the level of the cantilever. The support structure may be positioned or positionable below a deck or floor of the cantilever.

The method may comprise positioning the support structure below the cantilever, level of the cantilever, or deck/floor of the cantilever. The method may comprise aligning the tubular string with the well centre of the cantilever below the cantilever.

The support structure may be mounted on a deck surface of the rig, and extended from the deck surface over the side of the hull. In some example the support structure may be skiddable relative to the deck surface to be selectively extended and retracted over the side of the hull.

The support structure may be mounted to a side region of the hull. In one example the support structure may be positioned below a main deck level of the rig, at least when the support structure is in operation.

The support structure may be mounted to the cantilever. In an example the support structure may be mounted to the cantilever but configured to extend below the cantilever.

The support structure may be pivotally mounted relative to the hull of the rig to permit the support structure to be selectively extended and retracted.

The support structure may be retrofitted to an existing rig.

The support structure may be provided by an existing structure of the rig. In some examples the support structure may be provided by a secondary deployable deck. The support structure may be provided by a Texas deck on the rig. The method may comprise positioning the tubular string below the cantilever, the level of the deck region of the cantilever and/or level of the cantilever.. The method may comprise positioning the tubular string below the cantilever to be aligned with the well centre. A sufficient air gap may be provided to permit the tubular string to be positioned below the cantilever.

The method may comprise moving at least one of the well centre and the assembled tubular string to permit the tubular string to be aligned with the well centre.

In one example the method may comprise moving the assembled tubular string relative to the well centre to permit the tubular string to be aligned with the well centre. The tubular string may be moved separately from the support structure. Alternatively, the support structure with the tubular string suspended therefrom may be moved relative to the well centre/cantilever. The support structure may be skiddable relative to the hull.

In some examples the method may comprise transferring the support of the tubular string to the cantilever and subsequently moving the support structure to a retracted position. The method may comprise moving, for example skidding the cantilever relative to the assembled tubular string to permit the tubular string to be aligned with the well centre. The method may comprise transferring the support of the tubular string to the cantilever and then moving the cantilever to a desired position.

In some embodiments the present invention relates to a method for deploying a tubular string from an offshore rig comprising a hull and a cantilever, the cantilever defining a well centre and being extendable over a side of the hull, the method comprising:

providing a support structure separately from the cantilever, wherein the support structure extends from a side of the hull;

assembling multiple components to form a tubular string suspended from the support structure into a body of water, wherein the tubular string is off-set from the well centre of the cantilever; and

aligning the tubular string with the well centre of the cantilever.

In some embodiments the present invention relates to an apparatus for the offshore deployment of a tubular string, comprising:

a rig comprising a hull:

a cantilever defining a well centre, being configured to support a tubular string and being extendable over a side of the hull; and a support structure configured to be positioned separate from the well centre, wherein the support structure facilitates assembly of multiple components to form a tubular string suspended from the support structure;

wherein the tubular string is alignable with the well centre.

The well centre may be alignable with a tubular string suspended from the support structure

a rig comprising a hull:

a cantilever defining a well centre and being extendable over a side of the hull; and

a support structure provided separately from the cantilever, wherein the support structure extends from a side of the hull and facilitates assembly of multiple components to form a tubular string suspended from the support structure into a body of water; wherein the well centre is alignable with a tubular string suspended from the support structure.

The support structure may be moveable relative to the cantilever to provide alignment of a suspended tubular string with the well centre.

The cantilever may be moveable relative to the support structure to provide alignment of a suspended tubular string with the well centre.

The apparatus may be provided to perform the method according to any other embodiments. As such, features defined in relation to the method of any other embodiments may form part of the apparatus of any embodiments of the present disclosure.

In some embodiments the present invention relates to a method for retrieving a tubular string from an offshore rig comprising a hull and a cantilever, the cantilever defining a well centre and being extendable over a side of the hull, the method comprising:

supporting the tubular string on the cantilever along the well centre;

providing a support structure which extends from a side of the hull;

transferring support of the tubular string from the cantilever to the support structure;

moving the tubular string to a position which is off-set form the well centre while said tubular string is supported by the support structure. The method may further comprise disassembling individual components from the tubular string.

The method may comprise providing a support structure separated from the well centre, wherein the support structure extends from a side of the hull;

supporting the tubular string on the cantilever along the well centre and into a body of water;

moving the tubular string to a position which is off-set form the well centre while said tubular string remains extended into the body of water.

The method may further comprise disassembling individual components from the tubular string.

The method for retrieving a tubular string may be performed using the same apparatus to initially deploy the tubular string, for example as defined in relation to any other apparatus or method embodiments herein.

In some embodiments the present invention relates to an apparatus for the offshore retrieval of a tubular string, comprising:

a rig comprising a hull:

a cantilever defining a well centre, being configured to support a tubular string and being extendable over a side of the hull; and

a support structure configured to be positioned separate from the well centre. The support structure may facilitate disassembly of multiple components of a tubular string suspended from the support structure.

The tubular string may be alignable with the well centre.

The well centre may alignable with a tubular string suspended from the support structure.

a rig comprising a hull: a cantilever defining a well centre and being extendable over a side of the hull; and

a support structure provided separately from the cantilever, wherein the support structure extends from a side of the hull. The support structure may facilitate disassembly of multiple components of a tubular string suspended from the support structure into a body of water.

The well centre may be alignable with a tubular string suspended from the support structure. In some embodiments the present invention relates to an apparatus for the offshore deployment/retrieval of a tubular string, comprising:

a rig comprising a hull:

a support structure configured to be positioned separate from the well centre. The support structure may facilitate assembly/disassembly of multiple components of a tubular string suspended from the support structure.

The tubular string may be alignable with the well centre.

The well centre may be alignable with a tubular string suspended from the support structure.

In some embodiments the present invention relates to an apparatus for the offshore deployment/retrieval of a tubular string, comprising:

a rig comprising a hull:

a support structure provided separately from the cantilever, wherein the support structure extends from a side of the hull and facilitates assembly/disassembly of multiple components of a tubular string suspended from the support structure into a body of water;

wherein the well centre is alignable with a tubular string suspended from the support structure.

In some embodiments the present invention relates to a method for handling a tubular string using an offshore rig comprising a hull and a cantilever, the cantilever defining a well centre and being extendable over a side of the hull, the method comprising:

supporting the tubular string on the cantilever along the well centre;

providing a support structure; transferring support of the tubular string from the cantilever to the support structure;

moving the tubular string to a position which is off-set from the well centre while said tubular string is supported by the support structure; and

undertaking tasks along the well centre while said tubular string is supported by the support structure.

The tasks may be undertaken from the cantilever.

The support structure may act as a parking location for tubular strings while further tasks are undertaken on the well along the well centre. Such tasks along the well centre may comprise completion tasks. Such tasks might include drilling tasks.

The method may further comprise moving the tubular string to a second well centre.

The tubular string may be maintained in an assembled arrangement throughout. Accordingly, a tubular string may not need to be disassembled once it is no longer active on the well centre. A tubular string may be maintained in an assembled arrangement and may be moved to a second well centre belonging to a second well in an assembled arrangement, avoiding the need for reassembly of the tubular string.

In some embodiments the present invention relates to a method for retro-fitting an offshore rig which comprises a hull and a cantilever, wherein the cantilever defines a well centre, is configured to support a tubular string and is extendable over a side of the hull, the method comprising:

installing a support structure configured to be positioned separate from the well centre, wherein the support structure is configured to facilitate assembly and disassembly of a tubular string which extends from the support structure,

wherein the support structure and cantilever are moveable relative to each other between a first configuration in which the tubular string is off-set form the well centre, and a second configuration in which the tubular string support by the support structure is aligned with the well centre.

In some embodiments the present invention relates to a method for retro-fitting an offshore rig which comprises a hull and a cantilever defining a well centre and being extendable over a side of the hull, the method comprising:

installing a support structure which extends over a side of a hull, wherein the support structure is configured to facilitate assembly and disassembly of a tubular string which extends from the support structure and into a body of water,

wherein the support structure and cantilever are moveable relative to each other between a first configuration in which the tubular string is off-set form the well centre, and a second configuration in which the tubular string supported by the support structure is aligned with the well centre.

Further embodimentss of the present disclosure may relate to methods and/or apparatus for deploying and/or retrieving an elongate body to/from an offshore rig. In this respect, references to a tubular string and individual components thereof in any embodiments presented above may be substituted for any elongate body, tubular or otherwise.

It should be understood that features defined in relation to one embodiments may be applied in combination with any other embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other embodimentss of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 illustrates an example offshore jack-up rig; Figure 2 diagrammatically illustrates a front view of the rig of Figure 1 , with a cantilever extended;

Figures 3 to 9 diagrammatically illustrate sequential stages in the deployment of a tubular string from the rig of Figure 1 , wherein the rig is shown in side view in each of Figures 3 to 9; and

Figures 10 and 1 1 illustrate alternative sequential stages in the deployment of a tubular string from the rig of Figure 1 ; and Figure 12 is a further view of an example offshore jack— up rig.

DETAILED DESCRITPION OF THE DRAWINGS

Embodiments of the present disclosure relate to methods and apparatus for deploying and or retrieving a tubular string from an offshore rig. Any form of rig may be utilised. However, for the illustrative purposes only, the following description is provided with reference to a cantilever style jack-up drilling rig.

Figure 1 illustrates a jack-up drilling rig, generally identified by reference numeral 10. The rig 10 comprises a hull 12 and multiple jack legs 14 (three in the specific example disclosed) which extend downwardly through the hull 12 via respective jacking mechanisms 14. In Figure 1 the rig 10 is illustrated with the legs 14 fully jacked in a retracted position, such that the hull may float on the surface 16 of a body of water 18, and thus transported to a desired location. The rig 10 further comprises a drilling cantilever (or simply cantilever in the context of the present invention) 20 which is mounted on a deck surface 22 of the hull 12. The cantilever 20 is skiddable on the deck surface 22 so as to be extendable over a side of the hull 12 to preform desired operations. In the configuration of Figure 1 , however, the cantilever 20 is shown in a fully retracted position.

The cantilever 20 carries a derrick 24 which incorporates various equipment known in the art, such as a lifting or hoisting system 26. The cantilever 20 defines a well centre 28 wherein operations, such as drilling, deploying/retrieving equipment and the like, are performed along the well centre 28, normally utilising the hoisting system 26.

The rig 10 further comprises a retractable deck structure 30 mounted to the side of the hull 12 via hinged connections 32 at a location below the deck surface 22. In the present example the deck structure 30 includes two deck halves 30a, 30b which are illustrated in Figure 1 in a retracted position, specifically folded upwardly (pivoted about hinged connections 32). Various terms may be used in the art for such a deck structure 30, and in some examples the deck structure 30 may be referred to as a Texas deck. As will be described in further detail below, the deck structure 30 defines a support structure when extended.

The rig 10 further comprises various deck equipment, such as a deck crane 34.

Reference is now made to Figure 2 which diagrammatically illustrates the rig 10 of Figure 1 in front elevation view, and in an operational configuration. In this respect the legs 14 are jacked downwardly to engage the sea bed 36 and to raise the hull 12 above the surface 16 of the body of water 18. The cantilever 20 is extended over the side of the hull 12, and for illustrative purposes only is shown performing an operation, such as a drilling operation, along the well centre 28. The deck structure 30 is also shown deployed, extending generally perpendicularly from the side of the hull 12, and being located vertically below the level of the cantilever 20. However, as will become apparent from the following description, the cantilever 20 and the deck structure 30 are capable of being horizontally or laterally off-set from each other.

A sequence of operations for deploying a tubular string from the rig 10 will now be described with reference to Figures 3 to 9, which diagrammatically illustrate the rig 10 in side elevation, specifically the side of the rig 10 from which the cantilever 20 and support deck 30 extend. In the specific example the tubular string being deployed is a high pressure drilling riser, and reference to such will be made. However, it should be recognised that any form or type of tubular string may alternatively/additionally be deployed, such as a conductor, casing string, liner string or the like. Further, while the specific example of a tubular string being deployed is presented, it should be recognised that the present disclosure may also be used to deploy and elongate body, tubular or otherwise.

Referring first to Figure 3, the deck structure 30 (or support structure) is moved, for example via a skidding system (not shown), laterally along the side of the hull 12 to be laterally off-set from the well centre 28 of the cantilever 20. For illustrative purposes only, the cantilever 20 is shown performing an operation, such as a drilling operation, along the well centre 28, in which a structure 38 (such as a drilling string etc.) is suspended from the hoisting system 26 of the derrick 24, extending to and/or through subsea equipment 40 mounted on the seabed 36. The drilling operation may be performed to drill an initial surface bore, for example.

As will be described below, the deck structure 30 permits a drilling riser to be assembled without occupying the well centre 28, thus allowing simultaneous operations to be performed. This may provide time efficiencies, reducing required rig time and associated costs.

As noted above, the deck structure 30 is positioned to be laterally off-set from the well centre 28, as illustrated in Figure 3. In the specific example the two deck halves 30a, 30b are arranged with a lateral separation gap therebetween, and a tubular support apparatus in the form of a riser spider 42 is positioned to span across the gap. In other examples the tubular support apparatus may comprise a slip assembly or the like. The deck crane 34 may be utilised to place components which are intended to make up a lower portion of the drilling riser on the deck structure 30 (for example on one of the deck halves 30a, 30b), such as a lower connector package 44 and a stress joint 46. Once the stress joint 46 is connected to the lower connector package 44 and pressure tested if desired, the formed sub-assembly may be extended below the deck structure 30, and through the riser spider 42, using the deck crane 34, with a guide structure 48 optionally used to assist to guide and stabilise the upper region of the stress joint 46 during deployment. The riser spider 42 may function to support the stress joint 46, thus suspending the sub-assembly from the deck structure 30.

In a subsequent step, illustrated in Figure 4, a first intermediate riser joint 50a may be moved by the deck crane 34 from a storage bay 54 on the rig 10 and be presented, via the guide structure 48, to the upper end of the stress joint 46, with a connection between the stress joint 46 and the first intermediate joint 50 being made-up, for example by the riser spider 42, or any alternative connection mechanism. The created sub-assembly may then be lowered through the riser spider 42 via the deck crane 34, with the weight of the sub-assembly being transferred to the riser spider 42. At this stage, depending on the length of the individual components and the height of the hull 12 above the water surface 16, a lower end of the sub-assembly may be immersed within the body of water 18.

As illustrated in Figure 5, a second riser joint 50b is transferred from the storage bay 54 and connected, via the riser spider 42, to the upper end of the first intermediate joint 50a, with the sub-assembly then lowered further and suspended from the riser spider 42. This process of adding additional intermediate joints 50c-e transferred from the storage bay 54 may be repeated, as illustrated in Figure 6, until a desired length of a riser 56 is formed and suspended from the deck structure 30 into the body of water 18. In the present example the riser 56 is formed to have a sufficient length which places the lower connector package 44 approximately at the depth of the subsea equipment 40.

Subsequently, as illustrated in Figure 7, operations along the well centre 28 may be terminated with any deployed equipment retrieved, and the deck structure 30 and supported drilling riser 56 translated below the cantilever 20 such that the drilling riser 56 is generally aligned with the well centre 28. When in this position the lower connector package 44 is generally aligned over the subsea equipment 40.

As illustrated in Figure 8, the drilling riser 56 is then coupled to the hoisting system 26 of the derrick, such that the weight of the drilling string 56 may be transferred from the deck structure 30 to the cantilever 20. The deck structure 30 may remain in this position to support any operations to complete the assembly of the drilling riser 56, for example to include upper riser components such as a tension joint 58.

As illustrated in Figure 9, the completed drilling riser 56 may be secured to the subsea equipment 40 by establishing a connection via the lower connector package 44, and the deck structure 30 may optionally be moved or retracted from beneath the cantilever 20. In the example presented above the formed drilling riser 56 is aligned with the well centre 28 of the cantilever 20 by moving the deck structure 30. However, in an alternative example, where the rig 10 permits, the cantilever 20 may be laterally translated over the deck structure 30 and suspended drilling riser 56, as shown in Figure 10. The drilling riser 56 may be secured to the hoisting system 26 and, as illustrated in Figure 1 1 , the cantilever 20 moved to position the drilling riser as required, for example to be finally deployed as shown in Figure 9. The examples presented above illustrate the deployment of a tubular member. However, it should be recognised that the present disclosure extends to retrieval of a deployed tubular member. In this respect, the same apparatus may be used, generally in reverse operation, to permit retrieval.

Further, in some examples multiple tubular strings may be created and stored at an offset position.

Figure 12 shows a further example of an off-shore jack-up rig 10. The rig 10 comprises a hull 12 and multiple jack legs 14 (one being visible in Figure 12). A cantilever 20 comprising a deck region 21 (which in the present example is a drill floor) extends over the side of the hull 12. The rig 10 further comprises a supporting structure 31 comprising a deck region 33 and a tubular support apparatus 43 to support the tubular string 51 during and/or after its assembly.

In Figure 12, the tubular string 51 is assembled (at least partially) and is suspended from the tubular support apparatus 43 of the supporting structure 31 .

The supporting structure 31 is attached to a side of the hull 12 of the rig 10 by means of horizontal runners 49 along which the supporting structure 31 can skid. In the arrangement of Figure 12, the supporting structure 31 is positioned to support the tubular string 51 under the deck region 21 of the cantilever 20. The supporting structure 31 and tubular string 51 may in such an arrangement after the tubular string 51 has been assembled and before the support of the tubular string 51 is transferred to the cantilever 20, or after the support of the tubular string 51 has been transferred from the cantilever 20 to the support structure 31 .

It should be understood that the examples provided above are presented only for illustrative purposes of the present disclosure, and that various modifications may be made thereto. Further, the drawings presented are diagrammatic, and may not reflect actual scale.

Claims

1 . A method for deploying a tubular string from an offshore jack-up drilling rig comprising a hull and a cantilever, wherein the cantilever defines a well centre, is configured to support a tubular string and is extendable over a side of the hull, the method comprising:

providing a support structure separated from the well centre;

aligning the tubular string with the well centre of the cantilever.

2. The method according to claim 1 , comprising assembling multiple tubular components together to define or form the tubular string.

3. The method according to any preceding claim, comprising assembling multiple components to form a tubular string which extends below the hull.

4. The method according to any preceding claim, comprising securing individual components together on or at the level of the support structure.

5. The method according to any preceding claim, wherein the support structure comprises equipment for use in securing individual components together.

6. The method according to any preceding claim, wherein the tubular string is provided to extend between subsea equipment and the rig.

7. The method according to any preceding claim, wherein the tubular string is provided to extend into a wellbore.

8. The method according to any preceding claim, wherein the tubular string comprises at least one of a riser, a conductor, a casing string and a liner string.

9. The method according to any preceding claim, comprising completely assembling the tubular string prior to aligning with the well centre.

10. The method according to any one of claims 1 to 8, comprising partially assembling the tubular string prior to aligning with the well centre, and subsequently completing the assembly while aligned on the well centre.

1 1 . The method according to any preceding claim, comprising supporting the tubular string from the cantilever once said tubular string is aligned with the well centre.

12. The method according to any preceding claim, comprising transferring support of the tubular string from the support structure to the cantilever.

13. The method according to any preceding claim, comprising hoisting the tubular string once support of the tubular string has been transferred to the cantilever.

14. The method according to any preceding claim, wherein the cantilever comprises or supports a lifting system.

15. The method according to any preceding claim, comprising securing the tubular string to the lifting system of the cantilever once said tubular string is aligned with the well centre.

16. The method according to any preceding claim, comprising assembling components and progressively extending the length of the tubular string into the body of water.

17. The method according to claim 16, comprising assembling components to progressively extend the tubular string to a required length and thus depth within the body of water.

18. The method according to claim 17, wherein the tubular string is assembled such that a lower end is located in proximity to subsea well centre.

19. The method according to claim 18, comprising coupling the tubular string to the subsea well centre before or after being aligned with the well centre.

20. The method according to any preceding claim, comprising providing a tubular support apparatus on the support structure, wherein the tubular support apparatus functions to support the tubular string during and after its assembly.

21 . The method according to claim 20, comprising securing together adjacent components of the tubular string using the tubular support apparatus.

22. The method according to claim 20 or 21 , wherein the tubular support apparatus comprises at least one of a spider apparatus and a slip apparatus.

23. The method according to any preceding claim, comprising moving individual components from a storage position to be presented for assembly.

24. The method according to claim 23, comprising moving individual components with a transfer arrangement provided on the rig.

25. The method according to claim 24, wherein the transfer arrangement comprises a deck crane.

26. The method according to claim 23 or 24, wherein the support structure is positioned or positionable so as to be within an operational envelope of the transfer arrangement.

27. The method according to any preceding claim, comprising stabilising an individual component during connection with another component.

28. The method according to claim 27, comprising stabilising an upper region of an individual component during connection to another component using a stabilising guide.

29. The method according to any preceding claim, wherein the rig is a drilling rig and the cantilever is a drilling cantilever extendable over a side of the hull.

30. The method according to any preceding claim, wherein the support structure comprises a deck region.

31 . The method according to any preceding claim, further comprising the support structure raising and/or lowering the tubular string relative to the support structure.

32. The method according to any preceding claim, wherein the support structure permits downward passage of the tubular string and/or individual components therethrough.

33. The method according to claim 32, wherein the support structure defines an aperture therein to facilitate passage of the tubular string.

34. The method according to claim 32 or 33, wherein the support structure includes multiple components arranged side-by-side with a lateral separation gap therebetween to permit passage of the tubular string.

35. The method according to any preceding claim, wherein the support structure is provided on the same side of the hull and the cantilever.

36. The method according to any preceding claim, wherein the support structure is extendable and retractable over the side of the hull.

37. The method according to any preceding claim, wherein the cantilever is extendable and retractable over the side of the hull.

38. The method according to any preceding claim, wherein the cantilever is extendable from an outer side of the hull

39. The method according to any preceding claim, wherein the support structure is arranged on an outer side of the hull

40. The method according to any preceding claim, wherein the support structure is mounted to a side region of the hull.

41 . The method according to any preceding claim, wherein the support structure is positioned below a main deck level of the rig, at least when the support structure is in operation.

42. The method according to any preceding claim, wherein the support structure is provided by a Texas deck on the rig.

43. The method according to any preceding claim, wherein the cantilever comprises a deck region.

44. The method according to claim 43, further comprising raising the tubular string to the deck region of the cantilever.

45 The method according to any preceding claim, wherein the tubular string is suspended from the support structure below the level of the cantilever.

46. The method according to any preceding claim, comprising positioning the tubular string below the cantilever.

47. The method according to any preceding claim, comprising positioning the tubular string below the cantilever to be aligned with the well centre.

48. The method according to any preceding claim, comprising moving at least one of the well centre and the assembled tubular string to permit the tubular string to be aligned with the well centre.

49. The method according to any preceding claim, comprising moving the assembled tubular string relative to the well centre to permit the tubular string to be aligned with the well centre.

50. The method according to any preceding claim, comprising moving the support structure with the tubular string suspended therefrom to permit the tubular string to be aligned with the well centre.

51 . The method according to claim 50, comprising transferring the support of the tubular string to the cantilever and subsequently moving the support structure to a retracted position.

52. The method according to any preceding claim, comprising moving the cantilever relative to the assembled tubular string to permit the tubular string to be aligned with the well centre.

53. The method according to claim 52, comprising transferring the support of the tubular string to the cantilever and then moving the cantilever to a desired position.

54. An apparatus for the offshore deployment of a tubular string, comprising:

a rig comprising a hull:

a support structure configured to be positioned separate from the well centre, wherein the support structure facilitates assembly of multiple components to form a tubular string suspended from the support structure;

wherein the tubular string is alignable with the well centre.

55. A method for retrieving a tubular string from an offshore rig comprising a hull and a cantilever, the cantilever defining a well centre and being extendable over a side of the hull, the method comprising:

supporting the tubular string on the cantilever along the well centre;

providing a support structure;

disassembling individual components from the tubular string.

56. An apparatus for the offshore retrieval of a tubular string, comprising:

a rig comprising a hull:

a support structure configured to be positioned separate from the well centre, wherein the support structure facilitates disassembly of multiple components of a tubular string suspended from the support structure;

wherein the tubular string is alignable with the well centre.

57. An apparatus for the offshore deployment/retrieval of a tubular string, comprising: a rig comprising a hull:

a support structure configured to be positioned separate from the well centre, wherein the support structure facilitates assembly/disassembly of multiple components of a tubular string suspended from the support structure; wherein the tubular string is alignable with the well centre.

58. A method for handling a tubular string using an offshore rig comprising a hull and a cantilever, the cantilever defining a well centre and being extendable over a side of the hull, the method comprising:

supporting the tubular string on the cantilever along the well centre;

providing a support structure;

59. The method according to claim 58, wherein tasks along the well centre may comprise completion tasks.

60. The method according to claim 58 or claim 59, further comprising moving the tubular string to a second well centre.

61 . The method according to any of claims 58 to 60, wherein the tubular string is maintained in an assembled arrangement throughout.

62. A method for retro-fitting an offshore rig which comprises a hull and a cantilever, wherein the cantilever defines a well centre, is configured to support a tubular string and is extendable over a side of the hull, the method comprising: