FIELD

The present disclosure relates to a modular deck structure for an offshore rig, and also to a method of forming, such as retrofitting, a deck structure on an offshore rig.

BACKGROUND

In the offshore oil and gas industry wellbores are drilled below the seabed using specialised drilling platforms or vessels, known colloquially as drilling "rigs". Multiple types of drilling rig exist, such as fixed platforms, jack-up rigs, mobile offshore drilling units (MODUs), semi-submersibles, drilling ships 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, and the like. Once a well has been drilled and appraised, it will be completed with the appropriate downhole infrastructure to permit production (and/or injection), and then capped at the wellhead with a production tree, known as a X-mas tree. During the life of the well it may be necessary to perform workover or intervention operations. In many cases the operations which follow drilling of a well, such as completion and/or intervention operations, may dictate the use of separate service or workover rigs or vessels. For example, the original drilling rig may be of a form which might not accommodate efficient operations beyond drilling activities, for example by lacking suitable and conveniently located deck space and the like.

SUMMARY

An aspect of the present disclosure relates to a method for providing a deck surface on an offshore drilling rig, the method comprising installing a modular deck structure comprising a plurality of deck modules over at least a portion of a vertical riser storage bay provided for storing riser joints in a vertical orientation.

The method may utilise space, which is otherwise open, above or over the riser storage bay to permit the deck surface to be formed using the modular deck structure. This may permit available deck space on the drilling rig to be extended. Such additional deck space may improve the ability or effectiveness of the offshore drilling rig to be utilised to support additional operations beyond drilling operations, such as intervention operations and the like. Further, in some examples such additional deck space may facilitate more convenient location of equipment and the like on the formed deck surface.

Forming the deck surface from a plurality of individual deck modules may provide advantages in permitting improved handling and installation, for example by allowing easier manipulation and manoeuvring of individual modular components. Furthermore, the use of individual deck modules may permit a variation in the shape and/or size of the formed deck to be achieved, for example to form the deck around areas of the riser storage bay which remain open and operational.

The method may comprise retrofitting the deck surface on the offshore drilling rig. The method may comprise providing a temporary deck surface. For example all or part of the modular deck structure may be removable, for example to open up areas of the riser storage bay to receive riser joints, such as previously deployed riser joints.

The modular deck structure may extend over or cover 10% of the riser storage bay or more, such as 20% of the riser storage bay or more, such as 30% of the riser storage bay or more, such as 40% of the riser storage bay or more, such as 50% of the riser storage bay or more. The modular nature of the modular deck structure may facilitate a variation in the coverage of the riser storage bay to be achieved. In some embodiments the riser storage bay have an area of 100 m ² or more, such as 200 m ² or more, such as 300 m ² or more, such as 400 m ² or more.

The vertical riser storage bay is provided on the drilling rig to store riser joints vertically, in a convenient manner ready for deployment. The riser storage bay may be provided to accommodate the vertical storage of any suitable form of riser joints. In one example, the riser storage bay may be provided to accommodate the vertical storage of marine riser joints, such as drilling riser joints. The riser storage bay may be provided for the vertical storage of riser joints of any desired length/height. In one example, the riser storage bay may be provided for the vertical storage of riser joints of around 24.3 to 30.5 meters (around 80 to 100 feet) in length/height, for example. The method may comprise installing the modular deck structure over a portion of the riser storage bay which does not contain riser joints. For example, the method may comprise installing the modular deck structure subsequent to deployment or use of previously stored riser joints. In this respect, areas or regions of the riser storage bay which are empty may provide space for the installation of the modular deck structure. Accordingly, in some embodiments the one or more of the deck modules (such as most or all of the modules) of the deck surface is installed over an empty section of the riser bay i.e. which does not contain riser joints. In some embodiments the mounting of such one or more of the deck modules is structurally independent from any riser joints, such as on fixed structures of the rig. Such fixed structures may be existing infrastructure within the riser storage bay such as beams and/or the sides of the riser bay).

The riser storage bay may be positioned adjacent or in proximity to a derrick of the drilling rig. Such an arrangement may facilitate more efficient manipulation or transfer of the riser joints between the derrick and the riser storage bay. The derrick may facilitate operations, such as drilling operations, make-up and deployment of equipment (such as riser joints) and the like along a well-centre. In some examples, the derrick may be of a type which facilitates operations along multiple, for example two, well-centres. By forming the deck surface over at least a portion of the vertical riser storage bay, said deck structure may thus be provided in a convenient location in proximity to the derrick and associated well-centre(s).

The method may comprise aligning the deck surface formed by the modular deck structure with an existing deck, such as a main deck, of the drilling rig which is positioned adjacent the riser storage bay. The riser storage bay may extend downwardly from or below the existing deck of the drilling rig. The existing deck may define an opening into the riser storage bay. The existing deck of the drilling rig may define a drill floor deck.

The deck surface formed by the modular deck structure may be provided at the same height as the existing deck of the drilling rig. The deck surface formed by the modular deck structure may be arranged coplanar, for example flush, with the existing deck of the drilling rig.

Aligning the deck surface formed by the modular deck structure with an existing deck may effectively extend said existing deck. Furthermore, such alignment may facilitate ease of passage of equipment and personnel between the existing deck and the deck surface formed by the modular deck structure.

The method may comprise mounting at least part of the modular deck structure on existing infrastructure within the riser storage bay. In this respect, loading from the modular deck structure, and any load from equipment, personnel and the like, may be at least partially supported by said existing infrastructure. Thus, the deck surface formed by the modular deck structure may not rely solely on spanning an entire width of the riser storage bay, but instead finds support from existing infrastructure within the riser storage bay. Such an arrangement may also permit the formed deck surface to extend only partially over the riser storage bay, for example leaving portions of the riser storage bay open and free to accommodate riser joints and associated operations. Furthermore, by utilising existing infrastructure the requirement to provide dedicated load support structures may be minimised.

The method may comprise mounting the modular deck structure directly on existing infrastructure within the riser storage bay. Alternatively, the method may comprise indirectly mounting the modular deck structure on existing infrastructure, for example via one or more deck support modules, described below.

The existing infrastructure within the riser storage bay may extend generally horizontally. In one example, the existing infrastructure may extend from a side region of the riser storage bay, for example from a side wall region of the riser storage bay. The existing infrastructure within the riser storage bay may comprise infrastructure provided to enable desired vertical storage of riser joints. The existing infrastructure within the riser storage bay may comprise infrastructure for providing horizontal support to vertically stored riser joints. Such horizontal support may be provided at an upper region of a vertically stored riser joint.

The existing infrastructure may be located within the riser storage bay below a level of an existing deck. In some examples, the existing infrastructure may be between 0.1 and 10 meters below the existing deck, for example between 0.5 and 5 meters below the existing deck, such as between 1 and 2 meters below the existing deck. In one example, the existing infrastructure may be around 1 .2 meters below the existing deck. The method may comprise elevating the modular deck structure above the existing infrastructure to permit the formed deck surface to be aligned with the existing deck. The method may comprise elevating the modular deck structure via one or more deck support modules, described below.

The method may comprise modifying the existing infrastructure to accommodate the modular deck structure. For example, in some examples the method may comprise strengthening the existing infrastructure to accommodate loading applied once the modular deck structure is installed and operational. The method may comprise installing one or more structural components or features, such as brace features or the like, to the existing infrastructure.

In one example, the riser storage bay may comprise a plurality of riser guide beams which accommodate vertically stored riser joints therebetween, wherein the method may comprise mounting at least part of the modular deck structure on one or more of said riser guide beams. The riser guide beams may extend generally horizontally within the riser storage bay. Adjacent riser guide beams may be aligned generally parallel with each other. Adjacent riser guide beams may define a separation gap therebetween to accommodate one or more vertically orientated riser joints within said separation gap. The riser guide beams may extend from a side region of the riser storage bay. The riser guide beams may extend from a side wall of the riser storage bay, for example in cantilever form. In one example, the riser guide beams may be supported by one or more vertical columns. The vertical columns may extend upwardly from a floor of the riser storage bay.

The riser guide beams may be defined or known as riser bumpers, fingers or the like. The riser guide beams may be formed of metal, such as steel. The riser guide beams may comprise elongate members or structures. The riser guide beams may be of any suitable cross-section, such as an "H" section, " section or the like. The riser guide beams may comprise a covering, for example side coverings, for engagement with stored riser joints, for example to provide protection to the stored riser joints and/or the riser beams. The covering may comprise wood, rubber, foam or the like.

The method may comprise installing the modular deck structure on a plurality of support modules. The method may comprise installing a plurality of support modules, and installing the modular deck structure on said support modules. The method may comprise installing the support modules on existing infrastructure within the riser storage bay, for example on one or more riser guide beams or bumpers. The method may comprise securing the support modules to the existing infrastructure, for example via welding, bolting or the like. In one example, the method may comprise installing multiple support modules along the length of a single riser guide beam within the riser storage bay. The method may comprise installing multiple support modules along multiple riser guide beams.

The method may comprise supporting a single deck module on multiple support modules. In one example, the method may comprise supporting corner regions of a single deck module with different support modules. The method may comprise installing a single support module to provide support to multiple adjacent deck modules, for example two deck modules, three deck modules, four deck modules or the like. In one example, the method may comprise installing a support module at an interface between adjacent deck modules to provide support to said adjacent deck modules. The method may comprise installing a support module at a corner interface between adjacent deck modules, for example between two deck modules, three deck modules, four deck modules or the like.

At least two adjacent deck modules may define a geometry to facilitate relative positioning therebetween when installed. The geometry may permit an individual support module to provide support to the adjacent deck modules. For example, adjacent deck modules may comprise or define cooperating profiles or interleaving structures, allowing portions of the adjacent deck modules to be aligned with a single support module. This may provide advantages where the support module may be restricted to extend generally along an elongate structure, such as a riser guide beam within the riser storage bay. The cooperating profiles or interleaving structures may facilitate portions of adjacent deck modules to overlap each other in the plane of the formed deck surface.

A common form of interleaving structure may be provided between multiple adjacent deck modules. The interleaving structures of the deck modules may define or provide a repeating pattern across the deck surface. In one example, a first deck module may comprise a cut-out at a corner region, wherein a second deck module comprises a tab extension which extends into the cut-out of the first deck module when positioned adjacent each other. The method may comprise aligning the first and second deck modules with a support module which spans between the first deck module and the tab of the second deck module.

The first deck module may comprise a cut-out at two corners on a single edge of the first deck module, and the second deck module may comprise two tab portions extending from a single edge of the second deck module, wherein the tab portions of the second deck module are received within the respective cut-outs of the first deck module.

In one example, each corner of at least one deck module may comprise one of a cut-out and a tab portion. The form or geometry of the deck modules may vary in accordance with the location of the deck modules within the installed deck surface. For example, a deck module to be positioned adjacent an existing deck of the drilling rig may define a different geometry to a deck module to be located at a free edge of the formed deck surface. The modular deck structure may comprise multiple different types of deck module. For example, the modular deck structure may comprise at least one deck module of a first type and at least one deck module of a second type. Multiple additional types of deck module may be provided. The selection and installation of different deck module types may be performed in accordance with the desired form and geometry of the deck structure to be formed.

The support modules may define vertical pillar structures. The support modules may position the modular deck structure at a desired height, for example aligned with an adjacent existing deck of the drilling rig.

One or more of the support modules may comprise an interface for engaging a deck module. The interface may comprise a surface upon which a deck module sits. In one example, the interface may comprise a retaining structure. The retaining structure may prevent or restrict relative movement between a deck module and the support module in at least one direction. The interface may comprise at least one of a socket and a protrusion, and a deck module may comprise the other of a socket and a protrusion, wherein the protrusion is received within the socket. Such an arrangement may assist to ensure appropriate placement or positioning of the deck module. Further, such an arrangement may restrict lateral movement of the deck module relative to the support module.

The method may comprise securing the protrusion within the socket via a locking member, such as via a pin extending laterally through aligned holes on the socket and the protrusion. In one example, the pin may be tethered to one of the deck module and support module.

In one example, the interface may comprise a socket configured to receive a protrusion provided on a deck module. The socket may define an upwardly facing opening for receiving the protrusion, for example vertically receiving the protrusion from above.

One or more support modules may comprise a single interface. One or more support modules may comprise multiple interfaces, for example two, three, four or the like. The multiple interfaces may be provided for engaging or interfacing with respective multiple deck modules. In one example, multiple interfaces may be aligned side-by-side, along a common alignment axis. The common alignment axis may be aligned with existing infrastructure within the riser storage bay, for example along a riser guide beam or bumper. Multiple interfaces of a support module may be provided on a common support member. In one example, multiple interfaces may be provided on separate supports. For example, a support module may comprise a plurality of tubular members, wherein an upper end of each tubular member supports an interface. The method may comprise installing a support module on a side wall of the riser storage bay.

One, and in some examples each, deck module may comprise a frame and a deck plate mounted on the frame, wherein the deck plate defines a portion of the deck surface. The frame may comprise one or more structural members, for example metal members. The one or more structural members may comprise any suitable cross-section, such as an "H" section, T section or the like. The deck plate may comprise a sheet material, for example formed of metal, a composite or the like. The deck plate may be secured to the structural frame, for example via welding, screwing, bolting or the like. In one example, the deck plate may be secured to the structural frame via at least one threaded member, such as a screw, bolt or the like which extends through the deck plate to be secured to the frame. The threaded member may extend from an upper side of the deck plate to accommodate ease of installation.

In one example, the method may comprise replacing the at least one threaded member with a connecting member, to provide at least one lifting point to enable lifting and manipulation of the deck module. The connecting member may comprise an eyelet, hook, shackle or the like.

The method may comprise utilising a lifting frame to permit manipulating of a deck module. The lifting frame may be engageable with a lifting apparatus, such as a crane or the like. In one example, the method may comprise using a fork-lift, for example a fork-lift of a vehicle to engage a lifting frame.

The method may comprise installing a barrier on a previously installed deck module to prevent over-travel of equipment, such as a fork-lift vehicle. Such an arrangement may provide advantages during installation or retrieval of deck modules beyond the barrier, for example by minimising risk of equipment from accidentally falling into the riser storage bay, which would prevent serious risk to personnel and equipment. The barrier may be secured to the previously installed deck module via appropriate connection points which otherwise permit a deck plate to be secured to a frame of the deck module.

The method may comprise installing a barrier, such as a railing, around a periphery of the formed deck surface.

The drilling rig may comprise any offshore vessel, platform, installation or ship which can support drilling of a wellbore. The drilling rig may comprise a floating structure. In some examples, the drilling rig may comprise a semi-submersible. The drilling rig may comprise a drill ship An aspect of the present disclosure relates to a modular deck assembly to be installed on an offshore drilling rig at least partially over a vertical riser storage bay provided for storing riser joints in a vertical orientation, the modular deck assembly comprising a modular deck structure including a plurality of deck modules which collectively define a deck surface.

The modular deck assembly may be utilised to form a deck surface according to any other aspect.

The modular deck assembly may be mountable on existing infrastructure within the riser storage bay, for example on one or more riser guide beams or bumpers.

The modular deck assembly may comprise a plurality of support modules, wherein the modular deck structure is mounted on said support modules. The support modules may be mountable on existing infrastructure within the riser storage bay, for example on one or more riser guide beams or bumpers.

A single deck module may be supported on multiple support modules. In one example, corner regions of a single deck module may be supported by different support modules. A single support module may provide support to multiple adjacent deck modules, for example two deck modules, three deck modules, four deck modules or the like. In one example, a support module may be provided at an interface between adjacent deck modules to provide support to said adjacent deck modules. A support module may be provided at a corner interface between adjacent deck modules, for example between two deck modules, three deck modules, four deck modules or the like.

At least two adjacent deck modules may define a geometry to facilitate relative positioning therebetween when installed. The geometry may permit an individual support module to provide support to the adjacent deck modules. For example, adjacent deck modules may comprise or define cooperating profiles or interleaving structures, allowing portions of the adjacent deck modules to be aligned with a single support module. This may provide advantages where the support module may be restricted to extend generally along an elongate structure, such as a riser guide beam within the riser storage bay. The cooperating profiles or interleaving structures may facilitate portions of adjacent deck modules to overlap each other in the plane of the formed deck surface.

A common form of interleaving structure may be provided between multiple adjacent deck modules. The interleaving structures of the deck modules may define or provide a repeating pattern across the deck surface.

In one example, a first deck module may comprise a cut-out at a corner region, wherein a second deck module comprises a tab extension which extends into the cut-out of the first deck module when positioned adjacent each other. The first and second deck modules may be aligned with a support module which spans between the first deck module and the tab of the second deck module.

The first deck module may comprise a cut-out at two corners on a single edge of the first deck module, and the second deck module may comprise two tab portions extending from a single edge of the second deck module, wherein the tab portions of the second deck module are received within the respective cut-outs of the first deck module.

In one example, each corner of at least one deck module may comprise one of a cut-out and a tab portion.

The form or geometry of the deck modules may vary in accordance with the location of the deck modules within the installed deck surface. For example, a deck module to be positioned adjacent an existing deck of the drilling rig may define a different geometry to a deck module to be located at a free edge of the formed deck surface.

The modular deck structure may comprise multiple different types of deck module. For example, the modular deck structure may comprise at least one deck module of a first type and at least one deck module of a second type. Multiple additional types of deck module may be provided. The selection and installation of different deck module types may be performed in accordance with the desired form and geometry of the deck structure to be formed. The support modules may define vertical pillar structures. The support modules may position the modular deck structure at a desired height, for example aligned with an adjacent existing deck of the drilling rig. One or more of the support modules may comprise an interface for engaging a deck module. The interface may comprise a surface upon which a deck module sits. In one example, the interface may comprise a retaining structure.

The interface may comprise at least one of a socket and a protrusion, and a deck module may comprise the other of a socket and a protrusion, wherein the protrusion is received within the socket.

The protrusion may be securable within the socket, for example via a locking member, such as via a pin extending laterally through aligned holes on the socket and the protrusion. In one example, the pin may be tethered to one of the deck module and support module.

In one example, the interface may comprise a socket configured to receive a protrusion provided on a deck module. The socket may define an upwardly facing opening for receiving the protrusion, for example vertically receiving the protrusion from above.

One or more support modules may comprise a single interface. One or more support modules may comprise multiple interfaces, for example two, three, four or the like. The multiple interfaces may be provided for engaging or interfacing with respective multiple deck modules. In one example, multiple interfaces may be aligned side-by-side, along a common alignment axis. The common alignment axis may be aligned with existing infrastructure within the riser storage bay, for example along a riser guide beam or bumper. Multiple interfaces of a support module may be provided on a common support member. In one example, multiple interfaces may be provided on separate supports. For example, a support module may comprise a plurality of tubular members, wherein an upper end of each tubular member supports an interface. One, and in some examples each, deck module may comprise a frame and a deck plate mounted on the frame, wherein the deck plate defines a portion of the deck surface. The frame may comprise one or more structural members, for example metal members. The one or more structural members may comprise any suitable cross-section, such as an "H" section, T section or the like. The deck plate may comprise a sheet material, for example formed of metal, a composite or the like.

The deck plate may be secured to the structural frame, for example via welding, screwing, bolting or the like. In one example, the deck plate may be secured to the structural frame via at least one threaded member, such as a screw, bolt or the like which extends through the deck plate to be secured to the frame. The threaded member may extend from an upper side of the deck plate to accommodate ease of installation.

The at least one threaded member may be replaceable with a connecting member, to provide at least one lifting point to enable lifting and manipulation of the deck module. The connecting member may comprise an eyelet, hook, shackle or the like.

The apparatus may further comprise a barrier securable to at least one deck module to prevent over-travel of equipment, such as a fork-lift vehicle. Such an arrangement may provide advantages during installation or retrieval of deck modules beyond the barrier, for example by minimising risk of equipment from accidentally falling into the riser storage bay, which would prevent serious risk to personnel and equipment. The barrier may be secured to the previously installed deck module via appropriate connection points which otherwise permit a deck plate to be secured to a frame of the deck module.

The apparatus may comprise a railing around at least a portion of a periphery of the formed deck surface.

An aspect of the present disclosure relates to an offshore drilling rig, comprising:

a riser storage bay for storing riser joints in a vertical orientation; and

a modular deck assembly to be selectively installed at least partially over the riser storage bay, the modular deck assembly comprising a modular deck structure including a plurality of deck modules which collectively define a deck surface. The modular deck assembly may be provided in accordance with any other aspect. The deck surface may be aligned with an existing deck, such as a main deck, of the drilling rig which is positioned adjacent the riser storage bay. The riser storage bay may extend downwardly from or below the existing deck of the drilling rig. The existing deck may define an opening into the riser storage bay. The existing deck of the drilling rig may define a drill floor deck. The deck surface formed by the modular deck structure may be provided at the same height as the existing deck of the drilling rig. The deck surface formed by the modular deck structure may be arranged coplanar, for example flush, with the existing deck of the drilling rig.

At least part of the modular deck structure may be mounted on existing infrastructure within the riser storage bay.

The existing infrastructure within the riser storage bay may extend generally horizontally. In one example, the existing infrastructure may extend from a side region of the riser storage bay, for example from a side wall region of the riser storage bay.

The existing infrastructure within the riser storage bay may comprise infrastructure provided to enable desired vertical storage of riser joints. The existing infrastructure within the riser storage bay may comprise infrastructure for providing horizontal support to vertically stored riser joints. Such horizontal support may be provided at an upper region of a vertically stored riser joint.

The existing infrastructure may be located within the riser storage bay below a level of an existing deck.

The riser storage bay may comprise a plurality of riser guide beams which accommodate vertically stored riser joints therebetween, wherein the modular deck structure is mounted on one or more of said riser guide beams.

An aspect of the present disclosure relates to an offshore drilling rig, comprising:

a riser storage bay for storing riser joints in a vertical orientation, wherein the riser storage bay is operable in a mode in which a deck structure extends at least partially over said riser storage bay. The deck structure may be installed or formed according a a method of any other aspect. The deck structure may be provided in accordance with any other aspect.

When the deck structure is installed, said deck structure may block or prevent the storage of a riser joint at least below said deck structure

An aspect of the present disclosure relates to a method for performing offshore operations from a drilling rig, comprising:

deploying a plurality of riser joints from a vertical storage orientation within a riser storage bay; and

installing a modular deck structure over a portion of the vertical riser storage bay which does not contain any stored riser joints.

An aspect of the present disclosure relates to a method for providing a deck surface on an offshore drilling rig, the method comprising installing a deck structure at least partially over a riser storage bay provided for storing riser joints in a vertical orientation.

An aspect of the present disclosure relates to a method for installing a deck surface on a drilling rig. The method may comprise using a fork-lift, for example a fork-lift of a vehicle to install multiple deck modules to collectively define the deck surface.

An aspect of the present disclosure relates to a lifting frame for facilitating lifting of a deck module of a modular deck assembly. The lifting frame may be configured to be engaged by a fork-lift.

It should be recognised that the present disclosure extends to providing a combination of features from different aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure will now be further described, by way of examples only, with reference to the accompanying drawings, in which:

Figure 1 provides an aft view of an offshore semi-submersible drilling vessel or rig; Figure 2 provides a starboard side view of a portion of the drilling rig of Figure 1 ; Figure 3 provides a port side view of a riser storage bay provided on the drilling rig of Figure 1 , with a number of riser joints stored in the riser storage bay in a vertical orientation;

Figure 4 provides a simplified schematic top elevation view of the drilling rig of Figure 1 ;

Figure 5 provides a further simplified schematic top elevation view of the drilling rig, with a modular deck structure installed over a portion of the riser storage bay;

Figure 6 is a top elevation view of horizontal riser guide beams of the riser storage bay with a number of deck support modules installed thereon;

Figure 7 is a side elevation of one of the riser beam members of Figure 6 with the installed deck support modules;

Figure 8 illustrates a deck support module installed on a side wall of the riser storage bay; Figure 9 is a top elevation view of a first type of deck module;

Figure 10 is a cross-sectional view through line 10-10 of Figure 9;

Figure 1 1 provides a cross sectional view of a portion of the deck module of Figure 9, illustrating a connection between a deck plate and an underlying structural frame of the deck module;

Figure 12 is a cross-sectional view through line 12-12 of Figure 9, with a safety barrier installed;

Figure 13 is a top elevation view of a second type of deck module;

Figure 14 is a side elevation view of the deck module of Figure 1 3, with a safety barrier installed; Figure 15 illustrates a portion of multiple first and second deck modules of Figures 9 and 13 installed together to form a portion of a deck structure;

Figure 16 provides a top elevation view of an example completed deck structure formed form multiple types of deck module;

Figure 17 illustrates the installation/removal of a deck module using a fork-lift vehicle lifting frame; Figure 18 provides a cross-sectional view in the region of a lifting eyelet of the deck module being installed/removed;

Figure 19 provides a top elevation view of the lifting frame of Figure 17; and Figure 20 provides a front elevation view of a safety barrier to prevent over-travel of a fork-lift vehicle.

DETAILED DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure relate to the provision of a deck structure which extends over a riser storage bay provided on an offshore drilling rig. The drilling rig may be of any type. However, for purposes of providing an exemplary implementation, the following description refers to a semi-submersible drilling rig.

An aft view of a semi-submersible drilling rig, generally identified with reference numeral 10, is illustrated in Figure 1 . The drilling rig 10 includes pontoons 12 from which columns 14 extend upwardly, with a topside platform 16 supported by the columns 14. During operation, the drilling rig 10 floats at the sea surface with the pontoons 12 typically under the water and the support columns 14 positioning the topside platform 16 at an elevated position above the sea surface. To this end, the pontoons 12 may be filled with ballast water to cause the rig 10 to be submersed to the desired level.

The topside platform 16 includes multiple features, infrastructure and equipment which is used to perform desired operations, accommodate personnel and the like. For brevity, only certain features of the topside platform 16 will be described. In this respect, the topside platform 16 comprises a drill floor deck 18 and a dual activity mast or derrick 20 extending upwardly from the drill floor deck 18 and aligned in a transverse direction of the rig 10. The derrick 20 includes first and second hoisting systems 22, 24 which facilitate operations along respective first and second well-centres 26, 28.

Pipe storage and handling equipment 30 is mounted rearward of the derrick 20, and a riser storage bay 32 is positioned forward of the derrick 20 for storing riser joints in a vertical orientation. Figure 2 illustrates a portion of the rig 10 from its starboard side, illustrating the riser storage bay 32 with a number of vertically stored riser joints 34 therein. In the present example, the riser joints 34 are marine riser joints (e.g., drilling riser joints), which may be of a length/height of around 24.3 to 30.5 meters (around 80 to 100 feet). The riser storage bay 32 extends downwardly from the drill floor deck 18. Figure 3 provides a view of the rig 10 from its port side, in the region of the riser storage bay 32. The riser storage bay 32 includes infrastructure for ensuring suitable vertical storage of the riser joints 34. For example, the riser storage bay 32 includes a plurality of guide beams or fingers 36 (also known as riser bumpers) which extend horizontally, in cantilever form, from opposing side walls 38 of the riser storage bay 32 at a level below the drill floor deck 18, for example between 1 to 2 meters below. Individual riser joints 34 are positioned between adjacent guide fingers 36, such that the guide fingers 36 function to provide horizontal support to the vertically stored riser joints 34.

A riser joint gantry crane 40 is operable over the riser storage bay 32 to facilitate the transfer of individual riser joints 34 to/from the derrick 20.

A simplified and schematic illustration of the drilling rig 10, from above, is provided in Figure 4, which schematically illustrates the riser storage bay 32, including the vertically stored risers 34 and the guide fingers 36. For much of the operation of the drilling rig 10 many of the riser joints 34 will be deployed, such that sections of the riser storage bay 32 will be empty. As illustrated in Figure 5, the present disclosure provides methods and apparatus for the installation of a modular deck structure 42 comprising multiple deck modules 43 over a portion of the riser storage bay 32 following deployment of the riser joints 34. A more detailed description of such a modular deck structure will now be provided. Reference is now made to Figures 6 and 7, wherein Figure 6 illustrates a pair of the guide fingers 36 extending from the side wall 38 of the riser storage bay 32 with all riser joints originally stored between the guide fingers 36 removed and deployed, and Figure 7 provides a side elevation view of one of the guide fingers 36.

A plurality of deck support modules 44 are mounted at predefined locations along the length of the guide fingers 36. The deck support modules 44 may be secured to the respective guide fingers 36, for example via welding. The deck support modules 44 function as support pillars for supporting the modular deck structure 42, and are of a height to ensure that the modular deck structure 42, once installed, is aligned or flush with the adjacent drill floor deck 18.

Each support module 44 includes multiple support tubes 46 arranged side-by-side along the direction of the guide fingers 36 and interconnected at the upper end regions thereof via a plate 48. An interface 50 for engaging a deck module 43 is provided on the upper end of each support tube interface. In the present example, each interface 50 is provided in the form of a socket. In the present example, two variations or forms of support module 44 are provided, specifically a first form 44a which includes two support tubes 46 and interfaces 50, and a second form 44b which includes four support tubes 46 and interfaces.

It may be desirable in some circumstances to improve the structural capability of the guide fingers 36. In the example shown in Figure 7 the guide fingers 36 are originally mounted on vertical columns 52, and the structural capability of a free end 54 of the guide fingers 36 may be improved by use of a brace member or structure 56 which extends between the free end 54 of the guide fingers 36 and an associated column 52. In some circumstances it may be desirable to provide one or more further deck support modules remote from the guide fingers. For example, as illustrated in Figure 8 a deck support module 44 may be secured to a side wall 58 of the riser storage bay.

In the present example, the modular deck structure 42 comprises multiple different types or forms of deck module 43. A first type or form of deck module 43a is illustrated in Figure 9, with a cross-sectional view taken along line 10-10 provided in Figure 10. The deck module 43a includes a structural frame 60a and a deck plate 62a mounted on the structural frame 60a. As illustrated in Figure 1 1 , the deck plate 62a is secured to the frame 60a via screws 64 which extend through respective holes 66a in the deck plate 62a and engage a threaded bar 68 secured to the frame 60a.

The deck module 43a includes cut-out regions 70 at its four corners. Extending below the frame 60a adjacent each cut-out region 70 are vertical protrusions 72a. During installation the protrusions 72a are inserted into respective interface sockets 50 of the deck support modules 44 (see Figure 7). Locking pins 74a are tethered to the deck module 43a and used to lock the protrusions 72a within their respective interface sockets 50, by being inserted laterally through aligned holes on the interface sockets 50 and the protrusions 72a. In the present example, the deck module 43a further includes sockets 76a which, as illustrated in the sectional view of Figure 12 (taken along line 12-12 of Figure 9), receive railing 78a for forming part of a barrier around a periphery of the deck structure 42 when installed. A second type or form of deck module 43b is illustrated in Figure 13 in top elevation, with a side elevation provided in Figure 14. The deck module 43b is similar in many respects to module 43a, and includes a structural frame 60b and a deck plate 62b mounted on the structural frame 60b. Although not individually illustrated the deck plate 62b is secured to the frame 60b via screws, in the same manner as shown in Figure 1 1 with respect to deck module 43a, with the screws extending through holes 66b in the deck plate 62b.

The deck module 43b includes tab extensions 80 at its four corners. Extending below the frame 60b and aligned with each tab extension 80 are vertical protrusions 72b. During installation the protrusions 72b are inserted into respective interface sockets 50 of the deck support modules 44 (see Figure 7). Locking pins 74b are tethered to the deck module 43b and used to lock the protrusions 72b within their respective interface sockets 50, by being inserted laterally through aligned holes on the interface sockets 50 and the protrusions 72b. In the present example, the deck module 43b further includes sockets 76b which, as illustrated in Figure 14, receive railing 78b for forming part of a barrier around a periphery of the deck structure 42 when installed. A portion of a number of the first and second type of deck modules 43a, 43b when installed together is shown in Figure 15. In this respect, the deck modules 43a, 43b are mounted adjacent each other, such that the tab extensions 80 extend into the cut-out regions 70, permitting the protrusions 72a, 72b to be aligned along the direction of an underlying riser guide finger 36 and inserted within respective interface sockets 50 of the support modules 44a, 44b.

When installed in the manner illustrated in Figure 15, support modules 44a provide support to the corner region of two adjacent deck modules 43a, 43b, whereas support modules 44a provide support to the corner region of four adjacent deck modules 43a, 43b.

A complete deck structure 42 is illustrated in Figure 16. This deck structure 42 extends over the riser storage bay 32, and is adjacent and flush with the drill floor deck 18 of the drilling rig. The deck structure is composed of multiple different types or form of deck module, with the particular type or form selected in accordance with its location within the deck structure 42. In the example illustrated eight types of deck module 43 are provided, numbered 1 to 8. The first type of deck modules 43a first illustrated in Figure 9 are identified by numeral "2", and the second type of deck modules 43b first illustrated in Figure 13 are identified by numeral "3". Each type of deck module 43 includes a common form of interface (cut-outs and tab extensions), to facilitate appropriate mounting and support along the underlying guide fingers (not illustrated in Figure 16). As such, a repeating pattern is defined at the interfaces between the deck modules 43.

The modular deck structure 42 may thus be formed from a kit of parts.

In some examples, an operator may opt to modify the form of the deck structure as required, for example to form the deck structure 42 around used portions of the riser storage bay 32 and the like. Further, the modular nature of the deck structure 42 may permit an operator to readily modify the deck structure, for example to open up sections of the riser storage bay 32 to receive retrieved riser joints and the like. Once installed, the deck structure 42 may be used to support equipment and the like thereon. The position of the deck structure 42 on the drilling rig 10 (i.e., over the riser storage bay 32) is such that the deck may be reached by lifting equipment, such as cranes, provided on the rig 10. Furthermore, by the deck structure 42 being flush with the existing drill floor deck 18, vehicles, such as fork-lift vehicles may readily move between the existing deck 18 and the installed deck structure 42.

The additional deck space provided may permit the drilling rig to support additional functions, such as intervention operations and the like. In some examples, the deck structure may provide additional deck space for the storage of additional equipment, or at least provide additional deck space for appropriate handling of the equipment.

A method for the installation/removal of a deck module 43 is illustrated in Figure 17. In this case the deck module 43 being installed/removed is secured to a lifting frame 100 via chain or rope 102 which extends from suitable lifting brackets 104 on the frame 100 to lifting eyelets 106 secured to the deck module 43. In the present example, as illustrated in Figure 18, the lifting eyelets 106 are secured through the holes 66 in the deck plate 62 of the deck module 43 which are otherwise used to secure the deck plate 62 to the structural frame 60.

The lifting frame 100 is manipulated in the present example by a fork-lift vehicle 108. In this respect, the lifting frame 100 includes a pair of parallel box-members 1 10, illustrated in the top elevation view of Figure 19, to be engaged by a pair of forks 1 12 of the fork-lift vehicle 108.

During the installation/removal operation a barrier 1 14 is secured to the deck module 43 adjacent to the module being installed/removed. As illustrated in Figure 20, the barrier 1 14 is secured to the deck module 43 via screws 1 16 extending through holes 66 in the deck plate 62 of the deck module 43 which are otherwise used to secure the deck plate 62 to the structural frame 60. The barrier 1 14, when installed, may therefore permit over- travel of the fork-lift vehicle during operations.

It should be understood that the examples provided herein are indeed merely exemplary of the present disclosure, and that variations are possible.