WO2016165716A1

WO2016165716A1 - Drilling vessel

Info

Publication number: WO2016165716A1
Application number: PCT/DK2016/000014
Authority: WO
Inventors: Morten Norderud-Poulsen
Original assignee: Maersk Drilling AS
Current assignee: Noble Drilling AS
Priority date: 2015-04-17
Filing date: 2016-04-15
Publication date: 2016-10-20
Anticipated expiration: 2017-10-17

Abstract

Disclosed herein are embodiments of an offshore drilling vessel comprising: a hull, a moon pool defining an upwardly extending opening in the hull, an upper open deck, at least one further deck at a lower level than the upper open deck, at least one cargo lift configured for cargo transport between at least the upper open deck and the further deck.

Description

Drilling vessel Technical Field

The invention generally relates to offshore drilling vessels, such as drillships.

Background

Offshore drilling vessels are widely used in the exploration and exploitation of hydrocarbon reservoirs under the sea floor. One type of drilling vessel structure is a drillship, e.g. as described in WO 2014/108541.

It is generally desirable to provide an offshore drilling vessel that allows for an efficient and flexible operation. It is further generally desirable to provide an offshore drilling vessel that facilitates operation with a high degree of safety.

In order to efficiently support the drilling operations performed by such drilling vessels, considerable supplies, equipment or other types of cargo, have to be loaded and/or unloaded onto/from the vessel. Moreover, equipment or other cargo frequently has to be moved across the vessel, e.g. between various storage areas and the drill floor and/or to/from other locations where the cargo is needed. Some of this cargo is large and heavy.

Cargo is often loaded onto the vessel from supply ships, e.g. by means of on- deck cranes of the drilling vessel. The cranes allow the cargo to be positioned on an upwardly open upper deck of the drilling vessel, e.g. the drill floor deck. While drilling vessels may include a certain amount of storage area on the upper deck, these may not be sufficient for all cargo. Moreover, there are a number of reasons why it may be desirable to store cargo on lower decks: Some equipment may be needed at lower decks; it may be desirable to maintain the centre of gravity of the vessel low; it may be desirable to protect some cargo against whether conditions; it may be desirable to keep the upper deck, e.g. the drill floor deck, free from unnecessary cargo, etc.

It is thus desirable to provide a drill vessel that allows an efficient and safe movement of cargo across the vessel.

Summary

Disclosed herein are embodiments of an offshore drilling vessel comprising

- a hull,

- a moon pool defining an upwardly extending opening in the hull,

- an upper open deck,

- at least one further deck at a lower level than the upper open deck,

- at least one cargo lift configured for cargo transport between at least the upper open deck and the further deck.

Hence, efficient and safe movement of cargo between the upper open deck and one or more further decks is facilitated.

In some embodiments, the moon pool extends upwardly at least through the further deck, wherein the cargo lift is positioned on a first side of the moon pool, and wherein the further deck comprises a passageway for moving cargo, the passageway extending at least between the cargo lift and a position on a second side of the moon pool, opposite the first side.

Hence, efficient movement of cargo between the upper open deck and different locations on the further deck is facilitated and, in particular, movement to and from the moon pool area as well as to and from both sides of the moon pool. The cargo may comprise supplies, spare parts, other types of equipment, and/or the like. In particular, positioning of cargo through hatches by means of a deck crane can be reduced or even avoided, thus allowing for a safer movement of cargo by reducing the amount of blind lifts, and freeing the crane for other operations, e.g. for supporting time-critical operations such as the drilling operations.

Generally, the vessel may be oblong having two ends - a bow and a stern. The vessel may comprise a hull and a superstructure extending upwards above the hull. In some embodiments, the vessel comprises a midship portion between the ends. The midship portion of the hull is also referred to herein as mid-body. The mid-body may comprise at least 10%, such as at least 20%, such as at least 40% of the length of the hull, e.g. at least 50% such as at least 60%. The hull sides of the mid-body may be parallel, inclined, stepped or have a different shape. In some embodiments, the mid- body of the hull may have upright, substantially parallel hull sides.

The drilling vessel may further comprise a drill floor, one or more drilling support structures such as a derrick, a mast and/or the like and a hoisting system configured to raise or lower tubulars through a well centre and/or through another work centre in the drill floor. Examples of hoisting systems include draw-works hoisting systems and hydraulic hoisting systems. The drilling vessel may further comprise one or more top-drives and/or other equipment for imparting torque on a drill string.

The moon pool defines an opening in the hull to the sea through which equipment may be lowered from the drill floor towards the seafloor so as to allow drilling operation into the seabed for accessing of hydrocarbon reservoirs. The hull may comprise upwardly extending walls that surround and define a periphery of the moon pool. The moon pool may form a hole in the further deck and in all decks below the further deck and, optionally, in one or more decks above the further deck. The moon pool may be positioned at a central portion of the vessel, e.g. such that the centreline of the vessel extends through the moon pool and such that the longitudinal centre of the vessel extends to the moon pool. The term upper open deck is intended to refer to an open deck located at a level above the further deck. The upper open deck may be a deck above a main deck; it may extend all the way to the sides of the ship. It will be appreciated that there may be one or more openings in the upper open deck, e.g. for lowering equipment that is too large to be transported by a cargo lift - e.g. an x-mass tree - to the main deck. The term open deck refers to a deck which has at least an upwardly open portion accessible by a crane without the need for crane operations through hatches or the like. The upper deck may be formed as a part of a superstructure extending above the hull of the vessel. The upper deck may be the uppermost deck of the vessel. The main deck may be the highest deck extending substantially from stem to stern of the hull. The upper open deck may be the drill floor deck; it may provide an open drill floor deck allowing efficient movement of e.g. risers or other equipment to and from the well centre(s). For the purpose of this description, the term drill floor deck is intended to refer to the deck of a drilling vessel immediately above which joints of tubulars are assembled to form the drill string that is advanced through the well centre towards the seabed. The drilling vessel may include one or more further decks, e.g. one or more decks between the upper open deck and the further deck and/or one or more decks below the further deck and/or one or more decks at a level above the upper deck.

In some embodiments, the cargo lift is configured to service at least two decks having one or more rooms housing one or more items of installed equipment selected from the following set:

- a marine engine,

- a genset of 3MW or more, such as 5MW or more, such as up to 20MW,

- a mudpump,

- a thruster,

- drain treatment equipment, - water treatment equipment,

- a switchboard,

- other heavy tools. In some embodiments, the cargo lift is configured to service two or more service decks - e.g. two or more service decks, such as three or more service decks - for servicing subsea equipment, such as a BOP.

In some embodiments, the cargo lift is configured to service at least one deck, e.g. a deck above or below the main deck, comprising a plurality of rooms; wherein the cargo lift is located in a first one of said rooms; wherein the first room provides access through less than 3 doors to each of said plurality of rooms, such as via less than 2 doors, such as via one door, such as direct access.

The term well centre refers to a hole in the drill floor deck through which the drilling rig is configured to lower tubulars towards the seabed and, in particular, through which tubulars may be lowered all the way to the seabed. A well centre is sometimes also referred to as a drilling centre. It will be appreciated that, in addition to one or more well centres, the drill floor deck may comprise additional holes, e.g. one or more additional well centres and/or one or more other work centres through which tubulars may be lowered but through which tubulars may not necessarily be lowered all the way to the seabed. Such a work centre may even comprise a bottom which prevents tubulars from inadvertently falling to the seabed. Examples of such work centres include foxholes and mouseholes that may e.g. be used for building stands of tubulars but through which the drilling rig cannot lower tubulars to the seabed and/or through which the drilling rig cannot perform drilling into the seabed e.g. by lacking a system arranged to rotate a drill string with sufficient force such as a top-drive or a rotary table. In some embodiments, such an additional hole is a hole in the drill floor deck through which the drilling rig cannot progress a drill string through a riser system. In some embodiments, a well centre is differentiated from an additional hole by having a diverter and/or a diverter housing arranged below so that drill string passed through the well centre extends through said diverter or diverter housing. In some embodiments, the drilling rig is a dual (or even multiple) activity rig where more than one main or auxiliary drilling operations may be performed through two or even more separate work centres, one, some or all of which may be well centres. The part of the drill floor deck in immediate proximity of the well centre is normally referred to as the drill floor, which is the primary work location for the rig crew and/or machines performing similar functions, such as iron roughnecks. The drill floor normally comprises a rotary table for rotating the drill string. For the purpose of the present description, the term drill floor deck includes the drill floor located directly under/next to the mast and surrounding the well centre as well as deck areas on the same level as the drill floor, e.g. connected with the drill floor by uninterrupted floor area on the same level. The drill floor deck may thus include a deck area where human operators and movable equipment such as forklifts, equipment moved on skid beams, etc. can move around and to/from the well centre.

The drill floor deck is typically the lowest deck above the diverter system. Diverter systems for offshore drilling vessels are typically provided beneath the drilling rig rotary table. Such a diverter system provides a vent line and ensures that the flow may be directed away from the drilling rig. Hence, in some embodiments, the offshore drilling vessel comprises a diverter system under the well centre.

At least parts of the drill floor deck may be formed by the roof of a superstructure accommodating mud mixing equipment and/or other operational equipment of the drilling vessel, thus allowing for a compact and space-saving arrangement of equipment on the drilling vessel. The drill floor deck may comprise a storage area for storing tubular equipment such as drill pipes, casings, risers, etc., e.g. a storage area for storing tubular equipment in horizontal orientation. In some embodiments, a setback area may be lowered relative to the drill floor deck and the risers may be stored on the main deck.

In some embodiments the vessel comprises more than one cargo lifts, such as two, three or even more cargo lifts. The cargo lifts may e.g. be distributed along the length of the vessel, e.g. one cargo lift being located forward of the moon pool and another cargo lift being positioned aft of the moon pool. Alternatively or additionally, one or more cargo lifts may be located amidship, e.g. outboard from the moon pool. Hence, the first side may be the forwards side or the aft side or the starboard side or the port side of the moon pool.

In some embodiments, the cargo lift may be configured to transport cargo between two, three, or even more decks. In embodiments with more than one cargo lifts, the cargo lifts may all be configured to service the same decks, while in other embodiments, one or some cargo lifts may service one or more decks that are not serviced by one or more other cargo lifts. At least one cargo lift may service a lowermost deck, e.g. a tank top deck.

The or each cargo lift may be configured to transport cargo of sufficient volume and weight and, in particular, equipment other than drill pipes, marine risers and similar tubular equipment. For example, a cargo lift may be shaped and sized so as to allow transportation of cargo having a height of at least 2 m, such as at least 3 m, such as at least 4 m and a footprint of at least 2 m², such as at least 3 m², such as at least 5 m², such as at least 10 m². In some embodiments, the cargo lift is sized and shaped so as to allow transport of at least a 10-ft container. The cargo lift may be rated to transport cargo of at least up to 1000 kg, such as at least up to 2000 kg, such as at least up to 3000 kg, such as at least up to 5000 kg, such as at least up to 10000 kg, such as at least up to 15000 kg. In embodiments with multiple cargo lifts, the sizes and the weight ratings of the cargo lifts may be the same or different from each other.

The cargo lift may comprise a platform on which the cargo can be placed and a lifting means configured to elevate the platform with or without cargo between decks. Hence, the cargo lift is configured to provide vertical transport of cargo between two or more decks of the vessel. The cargo lift typically comprises one or more guides, e.g. rails, actuators, a shaft, and/or the like so as to facilitate a guided vertical movement and to prevent the platform from rotating and/or swinging. In some instances this guiding effect may be achieved by lift ifself as e.g. in the case of a scissor lift. The cargo lift may comprise an enclosure/cabin accessible through a door, or the cargo lift may be open to at least one side and/or upwardly open. The cargo lift may be driven by any suitable drive mechanism, e.g. by an electric motor or another type of motor. The drive mechanism may drive traction cables or counterweight systems, or it may pump hydraulic fluid to raise a cylindrical piston; one example of a cargo lift is a scissor lift like a jack. In some embodiments, the cargo lift is accessible from above, i.e. such that cargo may be lifted directly into the cargo lift from above. To this end, the cargo lift may be formed as an upwardly open platform that may be raised and lowered in a lift shaft. The platform may comprise a wall, fence or other delimiter along the periphery of the platform. The cargo lift may comprise a hatch or other cover allowing the cargo lift shaft and the upwardly open platform to be covered.

The passageway may be shaped and sized to allow movement of cargo by a forklift or other cargo transporters and/or to allow skiddable items to be moved along skid beams. Examples of cargo transporters may include one or more of the following: a ceiling mounted crane, trolley beams, an x-y crane, a gantry crane, a forklift, a pallet jack, a trolley. Accordingly, the cargo vessel may comprise one or more of such cargo transporters for transporting cargo to and from the cargo lift on said further deck and/or on other decks or platforms serviced by the cargo lift. In some embodiments, the passageway is equipped with or at least configured to allow transport by such a cargo transporter. In some embodiments, the passageway may at least partly be provided with a skidding arrangement to allow skiddable items to be moved. In some cases the passageway is free of skid beams and/or the skid beams are made flush with the floor. The passageway may have a width of at least 2 m, such as at least 3 m, such as at least 5 m. It may have a free height of at least 2 m, such as at least 3 m, such as at least 4 m. The passageway may be formed as a system of one or more interconnected passageway sections, e.g. a system of straight sections interconnected by bends. In some embodiments, the further deck may comprise one or more, e.g. two, longitudinal passageway sections extending in the forward/aft direction of the vessel, e.g. parallel to the centreline of the vessel. The longitudinal passageway sections may extend along the starboard and port sides of the moon pool, respectively. In embodiments with more than one longitudinal passageway sections, the passageway sections may be laterally spaced apart from each other and the longitudinal passageway sections may be connected by at least one athwartship passageway section.

In some embodiments, the longitudinally extending passageway section(s) may be located inside the perimeter defined by the hull, while in other embodiments, at least a part of the passageway - e.g. a part of a longitudinal passageway section - may be provided as a laterally outward extension of the midbody of the hull, such as at the uppermost end of the midbody portion of the hull. In some embodiments, the further deck is the main deck of the drilling vessel. Optionally, one, some or all cargo lifts may extend to one or more further decks below the further deck and/or between the further deck and the upper deck. It will be appreciated that one or more of these further decks may also comprise one or more passageways as described herein in connection with the further deck.

In some embodiments, the passageway extends substantially along the entire length of the further deck. In some embodiments, at least a portion of a longitudinal passageway section along the moon pool extends laterally outermost along the hull of the vessel, e.g. all the way at the starboard or at the port side. In some embodiments, substantially an entire midship portion of the vessel is provided with a laterally outermost longitudinal passageway sections extending along the hull on the starboard or the port side of the vessel; in some embodiments the further deck comprises respective longitudinal passageway sections along both sides of the hull. The longitudinal passageway sections may extend longitudinally parallel with the centreline of the vessel along at least a midship part of the vessel. The longitudinal and, optionally, parallel sections of the passageway may extend along at least 40%, such as at least 50%, such as at least 60% of the length of the vessel. The passageways may comprise one or more converging parts that converge towards each other, towards the bow and/or towards the stern of the vessel; thus, two or more passageways may converge partly or even completely towards each other, e.g. so as to continue as a common passageway section. In some embodiments, a cargo lift is located at the converging part of one or both passageway sections. A convergeing part of a passageway may be a passageway section that defines an angle relative to the centreline of the vessel, the angle being larger than 0° and smaller than 90° degrees. Alternatively or additionally, two spaced apart longitudinal passageway sections may be connected to each other by one or more lateral passageway sections that are oriented substantially perpendicular to the longitudinal direction of the vessel.

The drilling vessel may comprise a storage structure for storing tubular equipment, such as drill pipes, marine risers etc. Such a storage structure will also be referred to as a tubular storage structure. The term tubular equipment is intended to refer to tubular equipment that is advanced through the well centre towards the sea floor during one or more stages of the drilling operation. In particular, the term tubular equipment refers to straight tubular elements that can be joined to form a string of tubular equipment. The tubular equipment may be selected from drill pipes and/or other tubular elements of the drill string, risers, landing strings, liners and casings. Examples of tubular elements of the drill string include drill pipes, drill collars, etc. For the purpose of the present description, tubular equipment will also generally be referred to as tubulars. Tubulars may have varying lengths and diameters. Drill pipe typically has a length between 33' to 45' and diameters of up to 19" or even 20". Prior to advancement through the well centre, drill pipes are normally assembled to stands of two, three or even more stands of drill pipe, so-called doubles, triplets etc. The building of stands is performed by dedicated stand- building equipment and/or by a hoisting system. Once assembled, the stands are normally stored in a set-back area, typically in upright position supported by e.g. fingerboards. Riser joints typically have lengths between 50' and 90' and diameters of up to 70". In some embodiments, at least one tubular storage structure is arranged to store tubulars in vertical orientation. The tubular storage structure may be located at the same level as the drill floor deck or at least partially at a different level, e.g. on the further deck so as to allow tubulars to be advanced to the drill floor from below or along a slanted path. The tubular storage structure may be located on one of the outboard sides of the moon pool, i.e. on the starboard or the port side of the moon pool. The tubular storage structure may vertically intersect and extend below and/or above the further deck. The tubular storage structure thus defines an inboard side facing the moon pool and an outboard side facing away from the moon pool. A longitudinal extending passageway section on the further deck may be located laterally outward from the tubular storage structure; it may run along the outboard side of the tubular storage structure. In one embodiment, a cargo lift is located longitudinally adjacent (e.g. forward or aft of) the tubular storage structure. A passageway section may connect the cargo lift and the longitudinal passageway section.

The tubular storage structure may comprise a setback area. A setback area is a tubular storage area, typically in direct communication with one or more well centres, where tubulars can be stored ready and quickly retrievable by means of suitable pipe handling equipment to be lowered towards the seabed; similarly, tubulars can be conveniently set back in the setback area for later use. In a setback area, tubulars are typically stored vertically as this is convenient because the tubulars do not require a rotation before being run; however, tubulars may in principle be stored in horizontal position or both. These tubulars may also be stored in the setback area when tripping tubulars out of the well centre. Typically, a setback area is suitable for storing and receiving stands (i.e. 2 or more joined single tubulars, such as triplets) of drill pipe and/or casing in varying diameters. Storing tubulars in stands save time in a drilling operation because fewer connections have to be made when running in the hole (the well centre) and broken when tripping out of the hole. In such cases vertical storage is preferable because storing stands (which are typically very long) horizontally requires a large footprint. The setback area thus frequently extends vertically across multiple decks. The setback typically comprises equipment for holding the pipes, such as fingerboard systems for storing vertical tubulars, which will be designed to accommodate one or more diameters of tubulars. It is therefore typical that the setback has designated areas for holding e.g. drill-pipe and casings depending on diameter. In some embodiments, the setback further comprises pipe handling equipment (such as a pipe racker) arranged to deliver stands to and from the holding equipment of the setback area and present the stand to the hoisting system (typically the hook or top-drive) or hand over the stand to another machine in the pipe handling equipment (such as a chute or a further pipe racker machine) which performs the presentation. A setback area is also typically combined with stand building equipment which is arranged to receive single tubulars and connect those into a stand after which the stand is set back in the setback area ready to be run in the hole.

In some embodiments, the vessel comprises one or more cranes, such as one or more knuckle boom cranes, configured to transfer cargo from a supply vessel to a deck location adjacent to the cargo lift. In some embodiments, the vessel comprises 2 or more, such as 3 or more, such as 4 or more such cranes. In some embodiments, each cargo lift is accessible by at least one, such as at least two such cranes, such that the crane(s) can position cargo directly into the cargo lift. To this end the cargo lift may be upwardly open or be arranged to be opened upwards, e.g. by a hatch. Alternatively or additionally, the cranes and the cargo lift may be configured such that a crane can position cargo directly in front of or at least in close proximity to the respective cargo lift door, so as to allow the cargo to be conveniently moved into the cargo lift.

The present disclosure relates to different aspects including the drilling vessel described above and in the following, further aspects of a drilling vessel and corresponding methods and/or products. Each aspect may yield one or more of the benefits and advantages described in connection with one or more of the other aspects, and each aspect may have one or more embodiments with all or just some of the features corresponding to the embodiments described in connection with one or more of the other aspects and/or disclosed in the appended claims. Brief description of the drawings

The above and/or additional objects, features and advantages of embodiments and aspects of the present invention, will be further elucidated by the following illustrative and non-limiting detailed description with reference to the appended drawings, wherein:

FIG. 1 illustrates a cross sectional view along a centreline of an embodiment of an offshore drilling vessel.

FIG. 2 illustrates a deck layout of a drill floor deck of an embodiment of an offshore drilling vessel.

FIG. 3 illustrates a deck layout of a main deck of an embodiment of an offshore drilling vessel.

FIG. 4 illustrates a deck layout of a deck below the main deck of an embodiment of an offshore drilling vessel.

FIG. 5 illustrates a transverse cross sectional view of an embodiment of an offshore drilling vessel.

FIG. 6 illustrates a longitudinal cross sectional view of a midship portion of an embodiment of an offshore drilling vessel.

Detailed description

In the following description, reference is made to the accompanying figures, which show by way of illustration how the invention may be practiced.

FIGs. 1-3 illustrate an embodiment of an offshore drilling vessel. In particular, FIG. 1 illustrates a cross sectional view along a centreline of the drilling vessel; FIG. 2 illustrates a deck layout of a drill floor deck of the drilling vessel; FIG. 3 illustrates a deck layout of a main deck of the drilling vessel; FIG. 4 illustrates a deck layout of a tween deck, located below the main deck of the drilling vessel, FIG. 5 illustrates a transverse cross sectional view of the drilling vessel, and FIG. 6 illustrates a longitudinal cross sectional view of a midship portion of the drilling vessel.

The drilling vessel of FIGs. 1-6 is a drillship having a hull 101 , a moon pool 102, a main deck 115, a drill floor deck 107, and superstructures 197 and 106 extending above the hull and above the main deck. The superstructure 197 is located in the midship portion of the vessel and it extends above the moon pool. Superstructure 197 serves as a substructure supporting the drill floor and a dual activity mast 104.

The drill floor deck 107 is located at a level above the main deck and it spans across the moon pool 102 that is formed in the hull of the drillship. The drill floor deck 107 comprises two holes defining well centres 123 located next to a dual activity mast 104. The dual activity mast 104 extends upwardly from the drill floor deck 107 and comprises two mast portions arranged side by side such that they are both located on the same side relative to the well centres. Each mast portion accommodates a hoisting system, each for lowering a drill string 128 through a respective one of the well centres 123 and through the moon pool towards the seabed. In the example of FIG. 1 , the hoisting system is a hydraulic hoisting system. In alternative embodiments, other hoisting systems may be used, e.g. a draw-works system comprising a draw-works motor/drum which may be positioned at a suitable location on the drilling rig. Each well centre is located next to one of the mast portions and the corresponding hoisting system. The side-by-side configuration of the dual activity mast and well centres allows for efficient dual operations, easy access to both well centres, and convenient visual control of both well centres from a single driller^'s cabin. Alternatively, the vessel may comprise another suitable hoisting system, such as a single-activity, dual-activity or a multi-activity hoisting system which may be a drawworks system, a hydraulic system or another suitable type of hoisting system and which may be supported by a suitable drilling support structure such as one or more derricks, one or more masts, one or more towers and/or the like.

The drilling vessel comprises a setback area 112 or similar tubular storage structure for storing stands of tubulars such that the stored tubulars are located partly or completely below the level defined by the drill floor deck, i.e. below the uppermost platform of the superstructure 197, and partly covered by the drill floor deck 107. The setback area comprises a support framework supporting fingerboards having horizontally extending fingers between which tubulars may be stored. The setback area is positioned and arranged so as to allow stands to be moved to/from both well centres 123 from/to the setback area. To this end, on or more column rackers or similar vertical pipe handling equipment may be arranged to move stands into and out of the setback area 112. In some embodiments, e.g. in case of stands of drill pipe or casings, the tubulars may be taller than the drill floor. Hence, when they are stored in the setback structure in an upright orientation their uppermost ends may extend above the drill floor level. When feeding them to one of the well centres they may be laid into a chute as will be described below. The handling of tubulars within the setback area may be performed by vertical pipe rackers or the like. The setback area 112 further comprises stand building equipment configured to build stands from individual pieces of pipe. An example of such stand building equipment is described in WO 02/057593. Alternatively or additionally, stands may be built on the drill floor. In some embodiments, each mast portion and hoisting system form a respective gap between the two support members that carry the sheaves, through which gap tubular equipment is movable between the setback structure 112 towards the respective well centres. The mast structure 104 is located on one side of the well centres, and since the setback area 112 is located on the side of the mast opposite the well centres and/or behind the driller's cabin. Hence, the drill floor deck provides a large, unobstructed deck area on the side of the well centres opposite the mast. This area provides unobstructed access to both well centres and is free of pipe handling equipment. Consequently, these areas may be used as working area, e.g. for rigging up suspendable auxiliary equipment, and/or for positioning on-deck auxiliary equipment, e.g. wireline or coiled-tubing equipment.

The drilling vessel further comprises a pipe storage area 109 for storing pipes in horizontal orientation located aft of the moon pool, and a storage area 116 for storing marine riser joints located forward of the moon pool. In the present example, the storage areas 109 and 116 are located at a level below the drill floor deck; in particular, the storage area 116 is located on the main deck 115. One or more catwalk machines 108 or similar horizontal pipe handling equipment are arranged to feed tubulars from the storage area 109 to the well centres. To this end, the catwalk machine(s) may be aligned with the axis defined by the two well centres. Another catwalk machine may be used to provide riser joints to the hoisting system, load the riser storage 116 below the drill deck and/or to provide the drill floor with other tubulars. One or each of the catwalk machines may be operable to service both well centres. The drilling vessel comprises other storage areas below the drill floor deck 107, e.g. on the main deck 115 and configured for storing a variety of equipment, such as replacement parts, e.g. for mud pumps, etc.

The superstructure 106 is located in the forward part of the vessel and serves as an accommodation superstructure. The main deck 115 of the vessel is located beneath the drill floor deck and allows heavy subsea equipment 130, e.g. BOPs and Christmas trees to be moved to the moon pool under the well centres so as to allow such equipment to be lowered toward the seabed. Consequently, the drill floor deck and, in particular, the part of that drill floor deck that is located in close proximity to the well centre may be stationary and does not need to be hoisted or lowered for the subsea equipment to be lowered to the seabed. As is most easily seen in FIG. 2, the drill floor deck comprises a cut-out 238 that allows very heavy and large equipment such as an x-mass tree, BOP components, etc. to be directly placed on the main deck by a crane. Optionally, the vut-out 238 may be covered by a hatch. At the aft part of the vessel, a well test area 136 is arranged on a deck raised relative to the main deck.

At least parts of the superstructure 197 and/or the accommodation structure 106 comprise intermediate decks and/or platforms between the drill floor deck and the main deck. For example, as is best seen in FIG. 5, the vessel comprises a heavy tool store 539 located below the drill floor deck but above the main deck level. The heavy tool store may e.g. be convenient for storing equipment that may frequently be used on the drill floor. Similarly, the vessel comprises additional decks below the main deck. In particular, the lowermost deck is the tank top deck 124. Above the tank top deck 124, a lower tween deck 132 and an upper tween deck 133 are arranged. These decks extend across a part of the vessel. In the aft part of the vessel, a tween deck 135 is arranged at a level between the lower and upper tween decks. The drilling vessel comprises three cargo lifts 105, 110 and 113 and a lift 111 for transporting personnel. It will be appreciated, however, that the personnel lift 111 may also be used for transporting cargo and the cargo lifts may optionally be arranged for transport of personnel. Cargo lift 105 is located close to the centreline of the vessel and in the forward part of the vessel forward of the moon pool 102 and close to the accommodation superstructure 106. The cargo lift 113 is also located close to the centreline of the vessel, but in the aft part of the vessel, aft of the moon pool. The cargo lift 110 and the personnel lift 111 are located on respective outboard sides of the moon pool. Personnel lift 111 is located on the same side of the moon pool as the setback area 112 and forward of the setback area 112. Cargo lift 110 is located on the other side of the moon pool opposite the setback area. Each cargo lift is configured to transport cargo at least between the drill floor deck 107 and the main deck 115. As illustrated by horizontal arrows in FIG. 1 , at least some of the cargo lifts are further configured to transport cargo to/from additional decks, such as one or more decks between the main deck and the drill floor deck and/or one or more decks below the main deck. For example, in addition to servicing the main deck 1 5, cargo lift 110 allows equipment to be transported between the heavy tool store 539 and the drill floor deck 107. Cargo lift 105 services the drill floor deck 107, the main deck 115 and one or more decks of the superstructure 106 between the main deck and the drill floor deck. Access to the superstructure 106 from the cargo lift 105 may be provided by a connecting platform 137. Cargo lift 105 further services the tank top deck 124, the lower tween deck 132 and the upper tween deck 133. Cargo lift 113 services the drill floor deck 107, the main deck 115, one or more decks between the main deck and the drill floor deck as well as the tank top deck 124, the lower tween deck 132, the tween deck 135 and the upper tween deck 133. The cargo lifts may be configured to transport cargo of sufficient volume and weight. For example, a cargo lift may be shaped and sized so as to allow transportation of cargo having a height of at least 2 m, such as at least 3 m, such as at least 4 m and a footprint of at least 2 m², such as at least 3 m², such as at least 5 m², such as at least 10 m². The cargo lift may be rated to transport cargo of at least up to 1000 kg, such as at least up to 2000 kg, such as at least up to 3000 kg, such as at least up to 5000 kg, such as at least up to 10000 kg, such as at least up to 15000 kg. In the present example, at least cargo lifts 105 and 113 are shaped and sized to accommodate at least a standard 10-ft container. They each comprise a platform that is configured to be vertically movable in a lift shaft. The platform may be surrounded by a wall, fence or other protective structure. The lift shaft may be upwardly open or covered by a hatch or other cover that may be opened so as to allow cargo to be lifted directly onto the lift platform. The main deck comprises a system of interconnected passageway sections 117, 118, 122, 126, 127, 131 , respectively, that extend from the accommodation superstructure 106 close to the bow of the vessel substantially all the way to the stern of the vessel where well test area 136 is located on a deck raised relative to the main deck. All cargo lifts are located next to a passageway section such that they can be accessed from one of the passageway sections. The passageway sections of the system are shaped and sized so as to allow movement of cargo by a forklift or other vehicle and/or to allow skiddable items to be moved along skid beams. For example, at least some of the passageway sections may at least partly be provided with a skidding arrangement. The passageway sections may have a width of at least 2 m, such as at least 3 m, such as at least 5 m. It may have a free height of at least 2 m, such as at least 3 m, such as at least 4 m. At the main deck, the cargo lifts 105 and 113 are further surrounded by sufficient unobstructed space 329 and 340, respectively, to allow manoeuvring large items.

In particular, the main deck comprises two longitudinal passageway sections 117 and 122 extending along the hull along the midship part of the vessel at the starboard and port side of the vessel respectively. Hence, they extend along respective sides of the moon pool 102 and connect deck areas forward of the moon pool to deck areas aft of the moon pool, in particular deck areas inside the superstructure 197. Setback area 112 is located between longitudinal passageway section 122 and the moon pool, so as to allow stands to be transferred between the setback 112 and the drill floor without having to cross the passageway section 122. In particular, the longitudinal passageway sections 117 and 122 are arranged on outboardly extending portions 114 and 121 , respectively, e.g. platforms, that extend from the sides of the hull 101 outwards. It will be appreciated that the passageway system may also conveniently be used as evacuation routes for personnel in case of emergencies. Cargo lift 110 is positioned directly adjacent to and at the inboard side of longitudinal passageway section 17. Personnel lift 110 is connected to longitudinal passageway section 122 by an athwartship passage 125. Towards the bow of the vessel the passageways converge from the longitudinal passageway sections 117 and 122 towards a connecting space 329 at the centreline of the vessel by respective converging passageway sections 140 and 127 and extend towards the accommodation superstructure 106 by respective longitudinal sections 126 and 131. Cargo lift 105 is located next to or within the open space 329 from which the converging sections of the passageway extend.

Similarly, towards the stern of the vessel, the passageways converge from the longitudinal passageway sections 117 and 122 towards each other and an open space 341 at the centreline of the vessel by respective converging passageway sections 118 and 120 and extend towards the stern by a longitudinal section 119. Cargo lift 113 is located within or next to the open space 341.

The vessel comprises four deck cranes 103 arranged on the respective sides of the vessel and configured to move cargo across the drilling vessel and to/from the supply vessel. The cranes and cargo lifts are arranged such that each cargo lift can be reached by at least two of the cranes. Hence, generally, cargo from a supply vessel may be lifted off the supply vessel by one of the cranes, placed on the drill floor deck next to one of the cargo lifts or directly into one of the cargo lifts, transported to the main deck by the cargo lift and then moved, e.g. by a forklift or other vehicle along the passageway system to the desired location on the main deck. Alternatively, the cargo may be transported by the cargo lift to another deck and moved to a desired location on that deck. To this end, it will be appreciated that one or several of the other decks may also comprise a system of one or more passageways as described herein extending across a part or all of the corresponding deck.

FIG. 4 shows an example of a deck layout of the tween deck 135 at the aft part of the vessel. The tween deck is serviced by cargo lift 113. As indicated by arrows, cargo arriving with the cargo lift 113 may be moved, e.g. by a forklift to the areas/rooms/compartments of the deck, at least to the areas adjacent to the cargo lift, in this example engine rooms 434. In some embodiments, one or more x-y cranes and/or one or more trolley beams may be used to move cargo between the cargo lift and the engine rooms. Alternatively or additionally, a small trolley wagon may be used.

FIG. 6 illustrates a longitudinal cross sectional view of a midship portion of the drilling vessel. In particular, Fig. 6 illustrates the cargo lift 110 which services the drill floor deck 107, the main deck 115, the heavy tool store 539 below the drill floor deck and a number of BOP service platforms arranged at different heights relative to the BOP 130 at its storage position. To this end, the cargo lift 110 is located between the heavy tool store 539 and the BOP 130 which, in this example, is positioned on the main deck forward from the drill floor, such that it may be deployed trough the moon pool 102. The BOP may extend upwards to or even above the drill floor deck.

Even though the embodiments of FIGs. 1-6 have been described in the context of a drillship, it will be appreciated that the described features may also be implemented in the context of a semi-submersible or other type of drilling vessel.

Although some embodiments have been described and shown in detail, the invention is not restricted to them, but may also be embodied in other ways within the scope of the subject matter defined in the following claims. In particular, it is to be understood that other embodiments may be utilised and structural and functional modifications may be made without departing from the scope of the present invention.

For example, the described embodiments comprise two well centres, but it will be appreciated that alternative embodiments may comprise a single well centre or a well centre and additional work centres.

In the device claims enumerating several features, several of these features can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage.

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Claims

Claims:

1 . An offshore drilling vessel comprising:

- a hull,

- a moon pool defining an upwardly extending opening in the hull,

- an upper open deck,

- at least one further deck at a lower level than the upper open deck,

2. An offshore drilling vessel according to claim 1 ; wherein the moon pool extends upwardly at least through the further deck, wherein the cargo lift is positioned on a first side of the moon pool, and wherein the further deck comprises a passageway for moving cargo, the passageway extending at least between the cargo lift and a position on a second side of the moon pool, opposite the first side.

3. An offshore drilling vessel according to claim 1 or 2, wherein the upper open deck is a drill floor deck.

4. An offshore drilling vessel according to any one of the preceding claims, wherein the further deck is a main deck.

5. An offshore drilling vessel according to any one of the preceding claims, wherein the cargo lift is configured to service at least one deck having one or more rooms housing onr or more items of installed equipment selected from the following set:

- a marine engine,

- a genset of 5MW or more, such as up to 20mW,

- a mudpump,

- a thruster,

- drain treatment equipment, - water treatment equipment,

- a switchboard.

6. An offshore drilling vessel according to any one of the preceding claims, wherein the cargo lift is configured to service one or more service decks for servicing subsea equipment.

7. An offshore drilling vessel according to any one of the preceding claims, wherein the cargo lift is configured to service at least one deck comprising a plurality of rooms; wherein the cargo lift is located in a first one of said rooms; wherein the first room provides access through less than 3 doors to each of said plurality of rooms, such as via less than 2 doors, such as via one door, such as direct access.

8. An offshore drilling vessel according to any one of the preceding claims, comprising two or more cargo lifts, each configured for cargo transport between at least the upper open deck and the further deck.

9. An offshore drilling vessel according to claim 8; wherein a cargo lift is located aft of the moon pool and another cargo lift is located forward of the moon pool.

10. An offshore drilling vessel according to any one of the preceding claims, wherein at least one cargo lift is located at an outboard side of the moon pool.

1 1 . An offshore drilling vessel according to any one of the preceding claims, wherein the at least one cargo lift is shaped and sized so as to allow transportation of cargo having a height of at least 2 m, such as at least 3 m, such as at least 4 m.

12. An offshore drilling vessel according to any one of the preceding claims, wherein the at least one cargo lift is shaped and sized so as to allow transportation of cargo having a footprint of at least 2 m², such as at least 3 m², such as at least 5 m², such as at least 10 m².

13. An offshore drilling vessel according to any one of the preceding claims, wherein the at least one cargo lift is rated to transport cargo of at least up to 1000 kg, such as at least up to 2000 kg, such as at up to least 3000 kg, such as at least up to 5000 kg, such as at least up to 10000 kg, such as at least up to 15000 kg.

14. An offshore drilling vessel according to any one of the preceding claims, wherein the passageway is shaped and sized to allow movement of cargo by a forklift or other cargo transporter and/or to allow skiddable items to be moved along skid beams.

15. An offshore drilling vessel according to any one of the preceding claims, comprising one or more cargo transporters for transporting cargo on said further deck to and from the cargo lift, the cargo transporter being chosen from the following set of cargo transporters:

- a ceiling mounted crane,

- trolley beams,

- an x-y crane,

- a gantry crane,

- a forklift,

- a pallet jack,

- a trolley.

16. An offshore drilling vessel according to any one of the preceding claims, wherein the passageway has a width of at least 2 m, such as at least 3 m, such as at least 5 m.

17. An offshore drilling vessel according to any one of the preceding claims, wherein the passageway has a free height of at least 2 m, such as at least 3 m, such as at least 4 m.

18. An offshore drilling vessel according to any one of the preceding claims, wherein the further deck comprises one or more longitudinal passageway sections extending in the forward/aft direction of the vessel.

19. An offshore drilling vessel according to claim 18, wherein the further deck comprises two or more longitudinal passageway sections extending in the forward/aft direction of the vessel and wherein the longitudinal passageway sections are connected by at least one lateral or converging passageway section.

20. An offshore drilling vessel according to claim 18 or 19, wherein a longitudinal passageway section extends along the starboard or port side of the moon pool.

21 . An offshore drilling vessel according to any one of claims 18 through 20, wherein at least a part of the passageway is provided as a laterally outward extension of a midbody of the hull.

22. An offshore drilling vessel according to any one of the preceding claims; wherein the drilling vessel is a drillship or a semi-submersible.