Patent Grant
10323467
The present invention relates to an offshore drilling rig comprising a drill deck and a drilling support structure extending upwardly from the drill deck, and where at least one or two work centers are arranged in the drill deck, at least one of the work centers being a primary well center meaning that it is equipped for drillings operations using a diverter that can be connected to a mud return system, such as a marine riser or a mud return conductor being capable of conducting drilling mud from the sea floor to the offshore drilling rig.
Offshore drilling rigs of this kind are expensive to build and operate, and the continued development of this kind of rigs is therefore focused on providing a rig that will reduce the time of production, meaning that the time for drilling and installing the necessary equipment for e.g. oil production shall be as short as possible preferably without significantly increasing the costs of building and operating the rig.
For this purpose many different embodiments of offshore drilling rigs have been proposed during time.
On this background it is in some embodiments the purpose of the present invention to provide an offshore drilling facility that will increase the possibility of operating the rig, even when essential equipment is out of order, e.g. due to maintenance or breakdown.
In some embodiments of the present invention this is achieved by the rig as mentioned in the introduction further having two hoisting systems (a first and a second hoisting system supported by the drilling support structure and each being adapted for raising or lowering a load carrier (a first and a second load carrier, respectively), and by comprising a positioning system adapted for selectively positioning at least a first load carrier selectively in at least a first or a second position different from the first position, where the first load carrier in the first position is positioned above the primary well center, and in the second position is positioned above the other work center.
Thereby the two hoisting systems may operate over the same work center simultaneously or individually, so that when both hoisting systems are operative it will be possible to use both over the same work center or to use one over a work center and at the same time operating the other hoisting system over the primary well center, or another work center.
This allows that the rig is adapted for different modes of operation, including a dual activity mode where independent operations, such as drilling and standbuilding are simultaneously performed using both the primary well center and the other work center, or in a dual lifting mode where both hoisting systems cooperates for the purpose of lifting heavy loads above one work center, or in a redundancy mode where one hoisting system for some reason is disabled, and the other hoisting system is moved from one position to another in order to replace the disabled hoisting system.
For the purpose of the present description, the term drilling support structure means any construction extending upwardly from the drill deck and being equipped for supporting a hoisting system for hoisting and lowering tubulars (such as drill strings, casings and/or risers towards the seabed) so that drilling into the seabed can be performed. The drilling support structure may extend from the drill deck or from a deck different to the drill deck. The hoisting system is in this relation any system that provides a lifting capacity above one or more of the work centers arranged in the drill deck. This may in one embodiment of the invention be in the form of a hydraulic hoisting system comprising upwardly extending cylinders for supporting the load to be hoisted or lowered typically via cable sheaves mounted on top of the cylinders or alternatively it may be in the form of a conventional draw works system. Examples of a drilling support structure includes a derrick structure which are typically applied to support a draw works hoisting system and a mast structure which are typically applied to support a cylinder hoisting system.
The term work center refers to a hole in the drill deck through which the drilling rig is configured to lower tubular equipment towards the seabed and, in particular, through which tubular equipment may be lowered all the way to the seabed. A work center thus defines a downward passage extending through the drill deck through which tubular equipment may be lowered toward the seabed or even to the seabed. In this respect the term work center covers e.g. a well center, a mousehole, a rathole or a standbuilding foxhole, with or without different tools inserted into or supported from it, such as powerslips or other equipment.
A work center through which the drilling rig is configured to lower tubulars all the way to the seabed and/or through which the drilling rig can perform drilling into the seabed is often referred to as a well center. A well center is sometimes also referred to as a drilling center. It will be appreciated that the drill deck may comprise additional holes such as foxholes and mouse holes 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, a well center comprises a rotary table or a similar device allowing a drill string to be suspended by, or hung off in, the well center; to this end, a well center may comprise power slips or other devices operable to engage tubular equipment and to support the weight of the tubular equipment and, in particular, a string of tubular equipment extending to the seabed, so as to prevent the tubular equipment from descending through the well center. A displaceable well center may comprise a displaceable rotary table or a similar displaceable element comprising a hole and defining a downward passage.
A primary well center is in this relation a well center being adapted for drilling operations comprising a mud return system using e.g. a mud return conduit such as a marine riser typically used with floating drilling rigs or a high pressure riser (also sometime referred to as a conductor pipe) which is typically used on stationary offshore drilling rigs such as jack-ups. In this relation a primary well center is therefore differentiated from other work centers by having a diverter system including a diverter housing arranged below so that drill string passed through the primary well center extends through said diverter housing arranged for diverting e.g. blow outs to one side of the offshore drilling rig. Moreover, the drilling rig comprises a hoisting system, top drive and/or other equipment configured to operate through the primary well center and to perform drilling operations in the seabed. In some embodiments, the drilling rig may comprise a single primary well center or two or even more primary well centers. In addition to one or more primary well centers, the drilling rig may comprise additional work centers and or other additional holes in the drill deck through which the drilling rig cannot progress a drill string through a riser system or another mud return conduit.
The offshore drilling rig may be a semi-submersible drilling rig, i.e. it may comprise one or more buoyancy pontoons located below the ocean surface and wave action, and an operation platform elevated above the ocean surface and supported by one or more column structures extending from the buoyancy pontoon to the operation platform. Alternatively the offshore rig may be of a different type, such as a jack-up drilling rig or a drill ship.
The term tubular equipment is intended to refer to tubular equipment that is advanced through the well center towards the sea floor during one or more stages of the drilling operation. The tubular equipment may be selected from drill pipes and/or other tubular elements of the drill string, risers, liners and casings. Examples of tubular elements of the drill string include drill pipes, drill collars, etc.
For the purpose of this description, the term drill deck is intended to refer to the deck of an operating platform of an offshore drilling rig immediately above which joints of tubulars are assembled to form the drill string which is advanced through the well center towards the seabed. Hence the drill deck is the primary work location for the rig crew and/or machines performing similar functions, such as iron roughnecks. The drill deck normally comprises at least one rotary table for supporting the rotating drill string during drilling operations. For the purpose of the present description, the term drill deck includes the drill floor located directly under/next to the mast and surrounding the well center as well as deck areas on the same level as and connected with the drill floor area by uninterrupted floor area on the same level, i.e. the floor area where human operators and movable equipment such as forklifts, equipment moved on skidbeams, etc. can move around and to/from the well center; in some embodiments without having to climb/descend stairs or other elevations. The drill deck is typically the floor of a platform, e.g. the lowest platform, above the diverter system.
At least parts of the drill deck may be formed by the roof of a housing or enclosure accommodating mud mixing equipment and/or other operational equipment of the drilling rig, thus allowing for a compact and space-saving arrangement of equipment on the drilling rig. For example the drill deck may comprise a storage area for storing pipes, e.g. a storage area for storing pipes in horizontal orientation. The storage area may be located next to the between two horizontal pipe handling devices or, if this is movable, next to the path along which the horizontal pipe handling device may travel. In some embodiments, the pipe storage area and/or horizontal pipe handling equipment may be partially or completely surrounded by open drill deck area, e.g. drill deck area shaped and sized to allow vehicles or skidable items to be moved around the pipe storage area.
While the invention is applicable to rigs with two or more work centers any embodiments described herein may also be applicable where only one work hole is available (or used) with the lifting yokes, hoisting systems or load carriers. In such embodiments the other work center from the primary well center is replaced by the absence of a work center e.g. a blank.
In some embodiments the present invention relates to an offshore drilling rig is therefore proposed comprising two hoisting systems each comprising a lifting cable hanging over at least one cable crown being supported by the drilling support structure and each being adapted for raising or lowering a load carrier, and further comprising a positioning system adapted for selectively positioning each load carrier in a number of different horizontal positions comprising at least a first horizontal position above the primary well center, and a second horizontal position different from the first horizontal position, wherein the positioning system is adapted for positioning each cable crown above said first horizontal position above the primary well center, or said second horizontal position.
In some embodiments the present invention relates to an offshore drilling rig comprising at least one top drive and a positioning system adapted for selectively positioning the top drive in at least a first or a second horizontal position different from the first position, where the top drive in the first position is positioned above the primary well center, and where the offshore drilling rig further comprises a connecting tool being a connecting device having two opposite ends, each being adapted for being directly or indirectly connected to one of the load carriers, and where the connecting tool has an intermediate load carrier arranged between said two opposite ends and being adapted for carrying a load.
Thereby the two hoisting systems may be used simultaneously for providing the combined lifting capacity of each hoisting system in order to lift a load otherwise too heavy for one hoisting system e.g. out of the primary well center.
The hoisting systems may in this relation be any suitable hoisting system such as based on a draw works or a hydraulic cylinder configuration. In this relation the term cable crown covers any device supported by the drilling support structure and being adapted for supporting one or more lifting cables hanging below the drilling support structure beneath the cable crown. This may be in the form of a single cable sheave adapted for supporting one or more cables, or a cluster of cable sheaves being independently rotatable so as to constitute a crown block or a cable sheave cluster e.g. supporting a travelling block beneath the crown block. Furthermore the term load carrier in this relation means any device adapted for being carried by the hoisting system, and allowing a load to be connected to the load carrier. Examples of load carriers may be a load carrying hook, yoke, shackle or a travelling block.
In one embodiment of the present invention, each of the load carriers are connected to a lifting cable hanging from a cable crown (such as a cable sheave cluster or a crown block) supported by the drilling support structure, and the positioning system is adapted for shifting at least one of or each of the cable crown to and from a first and a second horizontal position relative to that cable crown where the load carrier is positioned right above a selected one of the work centers. The position of the cable crown is measured by the position of the load carrier. Also, by each of the cable crowns having at least two positions several configurations are possible including but not limited to the configurations where the rig having two working holes or three holes discussed below where the cable crowns have a common position in the middle and each have a second position to the side. In a configuration with two holes one or both cable crowns may be arranged to be positioned over both holes so that one can replace the other for redundancy and/or the load carriers may be arranged to lift together in one of the work holes.
The drilling rig may further comprise a connecting tool having two opposite ends each being adapted for directly or indirectly connecting it to one of the load carriers, so that the connecting tool can be carried by two different load carriers, and where the connecting tool has an intermediate load carrier being arranged between said two opposite ends and being adapted for carrying a load. In this way, it is possible to mount the connecting tool so that it is hanging below and between two load carriers, and thereby it is possible to provide a lifting power being higher than the lifting power of each of the hoisting systems by using both hoisting systems to lift the same load via the connecting tool.
In this relation, the positioning system may advantageously further be adapted for shifting each of the two cable crowns to a position right next to the first position, and so that the two load carriers are positioned on opposite sides of the first position.
Furthermore, the positioning system may advantageously comprise a retractable dolly arranged for each load carrier, and the retractable dolly being adapted to connect the load carrier to a vertically extending track preferably mounted on the drilling support structure, and to position the load carrier in the first and the second horizontal position above e.g. two different work centers and being adapted for positioning the load carrier at a distance from the track, so that it is positioned right above one of the work centers. In order to enable this function in practice it will be recognized that the retractable dolly may be adapted to reach a load carrier at a substantial horizontal distance from the vertically extending track, even where such a distance exceeds 4 or even 5 meters, such as exceeds 6 or even 7 meters, such as exceeds 8 or even 9 meters, such as exceeds 10 or even 11 meters, such as exceeds 12 or even 15 meters.
Especially in relation to rigs having a very large distance between the work centers, such as the above mentioned 10 meters the requirement to the reach provided by the retractable dolly is substantial. As such large dollies are not practical to operate fir different reasons, but also because it is expensive to implement dollies providing a substantial reach, then the offshore drilling rig may advantageously comprise at least three work centers arranged in the drill deck horizontally spaced apart from each other's in mutually different distances from the vertically extending track. Thereby it is still possible to provide the redundancy and increased lifting capacity even if the reach provided by retractable dolly connecting the top drive to the vertically extending track may be reduced so that it only allows the top drive to be vertically aligned above the two of the three work centers being closest to the vertically extending track.
In order to reduce the horizontally induced load on the retractable dolly it is in this relation preferred that the cable crown carrying a load carrier, and the retractable dolly connecting the same load carrier to said vertically extending track are adapted to keep the lifting cable between the cable crown and the load carrier substantially vertical.
It is understood that variations of the present invention may be made by applying a retractable dolly. Firstly, in some embodiments the retractable dolly comprises a load carrier for carrying loads extending into the work hole and the load carrier of the cable connected to the hoisting system is connected to the retractable dolly for providing vertical lifting power to the dolly. In combination of alternatively, the retractable dolly may be provided to offset the load carrier connected the cable from the position it would have based on the position of the cable crown and no retractable dolly. Typically, it is advantageous if these two positions are substantially aligned so the lift provided by the hoisting system via the cable is substantially vertical. However, by providing such offset via the dolly less movement may be necessary of the cable crown which may be a faster and/or simpler way of changing position of the load carrier. Accordingly, in some embodiments the position of the cable crown refers to the position of the load carrier as provided by the cable crown and the dolly in combination. In some embodiments the position of the cable crown refers to the position of the load carrier as it would have been without a retractable dolly influencing the horizontal position.
In another preferred embodiment the two work centers are mounted in a substantially horizontal track in the drill deck, and the drill deck comprises a work center positioning system adapted for selectively moving at least one of or each of the work centers in the horizontal track to the first or the second position in the drill deck.
In this relation the horizontal track may preferably be linear at least along a part of it, and the diverter system may comprise at least one diverter over board tube having a first end being connected to the primary well center and the other end being supported and fixed with respect to the drill deck and having at least one telescopic section between the first and the second end, the telescopic section extending parallel to linear part of the horizontal track in the drill deck. Thereby the diverter over board tube, which may be directing well fluids under high pressure from the diverter and over board, is relatively easy to keep tight during drilling operations e.g. by using a hydraulic, pneumatic or mechanical packer to tighten and seal the telescopic section during drilling operations.
The drilling rig may advantageously further comprise at least one riser tensioning arrangement below the drill deck, and where the riser tensioners are mounted on linear tracks for repositioning, and in parallel to the horizontal track in the drill deck, so that the riser tensioners can be positioned below either of the work centers and/or below either of the first or second positions.
In some embodiments each load carrier is lifting a top drive, which in some embodiments is considered a load carrier itself.
In a further preferred embodiment, two work centers may both be primary well centers comprising a rotary table and a diverter system arranged in the drill deck.
In yet a further preferred embodiment, the shifting means is adapted for shifting each of the cable crowns along a line being parallel to the linear part of the horizontal track in the drill deck.
In the context of this description the terms of moving, positioning, skidding shifting and so on is meant to include the process of displacing a component or part from one position to another, but also the necessary means for holding or fixing the component or part at a selected position during operation of the drilling rig.
In the following one or more embodiments of the invention will be described in more detail and with reference to the drawing, where:
From each of the crown sheave clusters 5a and 5b lifting cables 7a and 7b are running down and connecting to a load carrier 8a and 8b each carrying a top drive 9a and 9b at the end of the lifting cables 7a and 7b. Each of the top drives are connected via a retractable dolly 10a and 10b to a vertical track 11a and 11b arranged at the drilling support structure 1. The retractable dollies 10a and 10b are each adapted so that they can position and keep the top drives in different positions above the work centers 3a, 3b, 3c in the drilling deck 2.
In the embodiment shown on
Alternatively the drilling support structure 1 shown on
The embodiment shown in
The skilled person will, however, appreciate that the mere combination of the skidable crown sheave clusters 5a, 5b shown on
For the same reason each cable winch 27a, 27b shown in
In
The diverter housing 13 has at least two outlet ports 17a and 17b each being connected to telescopic overboard lines 18a and 18b. This allows the diverter housing 13 to be positioned at different positions along a line defined by the track 4 being parallel to the overboard lines. One such position is shown in
The diverter housing 13 also comprises a mud return outlet port 19 adapted for leading drilling mud from the diverter housing back to the mud process systems via the main mud return line system 20. The mud return line comprises a number of telescopic connectors 21a 21b and 21c arranged at selected positions in order to connect the mud return line to the mud return outlet port 19 on the diverter housing 13.
In
In the following different modes of operating the drilling rig shown in the figures are disclosed in more detail with reference to the relevant figures.
1. Full Redundancy:
With reference to
Full redundancy is achieved by having a transferable, riser-capable primary well center 3a, which may be positioned under either one of the top drives (e.g. 9a or 9b) and load carriers (8a and 8b) of the two fully rated main hoisting- and drilling systems comprising the facility. In this relation the primary well center may be transferred and positioned as mentioned above, with or without one tubular or a string of tubulars 35, such as riser tubes, casings, drilling pipes or the like being supported and/or hanging down from the primary well center, and these tubulars may be either hanging freely down from the primary well center, or they may extend all the way to the sea floor and further extend into the well or be connected to the well at the sea floor. In the latter case a diverter system and a tensioning system as shown on
The riser-capable primary well center 3a shall consist of a rotary table 14 supported by a horizontally transferable skid/trolley 25 that is sunk into a slot in the drill deck 2, so that the rotary table 14 top cover is substantially flush with the drill deck 2 level.
The transferable skid/trolley 25 shall be resting on horizontal skid beams forming a track 4 spanning the width between the two fully rated main hoisting- and drilling systems 9a and 9b.
A diverter housing 13 with telescoping overboard lines (overboard tubing 18a and 18b) and a detachable main flowline (mud return tubing 20) shall be suspended from underneath the said transferable skid/trolley 25.
A transferable/skidding riser tensioning system shall be arranged on horizontal skid beams suspended from underneath the drill deck structure, while spanning the full width between the two fully rated main hoisting- and drilling systems.
Following examples are given for the intended operation to ensure full redundancy e.g. in the case that the one (active) fully rated main hoisting- and drilling system suffers a main equipment breakdown:
The fully redundant dual activity hoisting- and drilling facility illustrated in
2. Cyclic Dual Hoisting:
With reference to
Fast tripping, casing- or riser running operation is ensured by having two independent and fully redundant hoisting- and drilling systems (top drives 9a and 9b) working in cyclic operation over a common primary well centre 3a.
Each hoisting and drilling system shall consist of a main hoisting system with a horizontally transferable cable crown in the form of a crown sheave cluster arrangement 5a, 5b, allowing the crown sheave cluster 5a, 5b to be horizontally transferred, aligned and locked into position over at least two independent positions/well centers 3a, 3b, 3c on the drill deck 2 below.
Each hoisting system supports a vertically travelling load carrier 8a, 8b arrangement, from which a topdrive 9a, 9b is suspended below on a horizontally extend-/retractable dolly 10a, 10b system for guiding of the topdrive 9a, 9b.
The extend-/retractable dolly 10a, 10b shall have a horizontal travel corresponding with the horizontal travel of the crown sheave cluster 5a, 5b arrangement above, while extending/retracting horizontally in synchronous motion with the skidding crown sheave cluster 5a, 5b arrangement above, ensuring that the hoisting system is kept in true vertical alignment with the cable sheave cluster/load carrier/yoke/hook arrangement and the topdrive 9a, 9b suspended underneath it.
In the following typical examples are given for the intended cyclic operation of the dual hoisting and drilling facility to provide fast tripping, casing or riser running operation:
Fast running or retrieval of the riser and BOP may be performed in a similar cyclic operation, while employing suitable arrangements for facilitating handling of the riser joints to/from the primary well centre 3a with this being in the center position
An added benefit of the invention is the full redundancy provided within this facility in that each hoisting and drilling system will offer full redundancy for the other system in the center operating position, without repositioning of the primary well centre 3a.
With reference to
The synchronous hoisting facility is realized by utilizing the two independent and fully redundant hoisting- and drilling systems in a combined synchronous mode of lifting operation above the common primary well center 3a, by using a connecting tool 12.
In
This principle allows for extra heavy duty lifting operation without necessitating any of the two hoisting- and drilling systems to be rated beyond the current design loads of such equipment, where especially the load capacity of the topdrives 9a, 9b are limiting the load capacity of the hoisting systems.
Recurring requests for rigs capable of running extended sections of heavy wall casing strings through deep formations in ultra-deep water may require lifting facilities of 1500 metric tons SWL or beyond.
Current designs of hoisting and drilling systems are limited to approx. 1200 metric tons only, with systems and equipment currently under design and development for up to 1500 metric tons.
Consequently, the next generation of DW drilling rigs may only provide incrementally larger hoisting capacity compared with the current generation of rigs and will therefore restrict well designs to within the 1500 metric tons limit of the next generation of top drives.
However, this invention will allow for hoisting and lowering loads exceeding 2000 metric tons, limited only by the structural integrity and load carrying capacity of the casing and landing string tubulars, running- and handling tools. A generic ultra-deep subsalt and/or HPHT well development program in ultradeep water might utilize all aspects of the invention to their full potential through the following steps and transitions between modes of operation:
A top drive 9a, 9b is suspended from each of the load carriers, and the offshore drilling rig comprises a positioning system adapted for selectively positioning at least the one load carrier or the primary well center selectively in at least a first or a second horizontal position different from the first horizontal position, where the first load carrier in the first horizontal position is positioned above the primary well center, and in the second horizontal position is positioned above the other work center.
In particular,
Generally, a skidable arrangement of equipment allows the displacement, in particular horizontal displacement, of the equipment, e.g. guided by tracks or similar guide means.
The drilling rig of the present embodiment comprises a drill deck 2 formed on top of a substructure 1597. The substructure comprises a platform supported by legs. The platform defines the drill deck and spans across a moon pool 2122 formed in the hull of the drillship. The drill deck 2 comprises two holes defining well centres 3a,b. The drilling rig comprises a drilling support structure in the form of a mast 1. In the present example, the well centres are located within the footprint of the mast 1. The mast includes two mast portions, each associated with, and adjacent to, one of the well centers. The dual activity mast 1 is supported by the substructure 1597 and extends upwardly from the drill deck 2. The mast comprises two mast portions arranged in a face-to-face configuration, i.e. the respective mast portions are located along the axis connecting the well centres such that both well centres are located between the mast portions. Each mast portion supports a hoisting system, each for lowering a drill string through a respective one of the well centres 3a,b towards the seabed. In the example of
From each of the cable crowns lifting cables 7a,b are running down and connect to a corresponding top drive 9a,b which is suspended from a hook or other load carrier connected to the lifting cables. Each of the top drives is connected via a retractable dolly 10a,b to a vertical track arranged at the mast 1. The retractable dollies are each adapted so that they can position and keep the top drives in different positions above the well centers, as described herein.
Each hoisting system has one or more linear actuators in the form of a hydraulic cylinder 28a,b having its lowermost end fixed with respect to the drill deck and an upper travelling end with a cable sheave. At least one lifting cable has one end extending from another hydraulic cylinder arranged for compensating heave during e.g. drilling operation, and over the travelling cable sheave and further below a second cable sheave being fixed with respect to the mast, and thereafter over the cable crown. The hydraulic cylinders are displaced from the well centres along the direction connecting the well centres and positioned such that both well centres are located between the cylinders of the respective hoisting systems. As can be most easily seen on
As is most easily seen in
The drilling rig further comprises a pipe storage area 1509 for storing pipes in horizontal orientation and catwalk machines 1508 or other horizontal pipe handling equipment for transporting pipes between the storage area 1509 and the well centers 3a,b. To this end, the catwalk machines are aligned with the axis defined by the two well centres.
The drilling rig comprises a setback structure 1812 or similar pipe storage structure for storing stands of tubulars below the substructure 1597 and partly covered by the drill deck 2. The setback structure comprises a support framework 1890 supporting fingerboards having horizontally extending fingers between which tubulars may be stored. The setback structure is arranged so as to allow stands to be moved to/from both well centres from/to the setback. To this end, one or more column rackers 1891 or similar vertical pipe handling equipment may be arranged to move stands into and out of the setback structure 1812. The setback structure 1512 further comprises stand building equipment 1877 configured to build stands from individual pieces of pipe. The setback structure 1812 is located adjacent the moon pool 2122 laterally displaced from the axis defined by the well centers.
Moreover the drilling rig comprises one or more further catwalk machines 1876 configured to feed tubulars from the pipe storage area 1509 or from other storage areas on the opposite side of the mast (towards the aft of the ship) to the stand building equipment 1877. The stand building equipment 1877 may thus receive the pipes from the catwalk machine 1876, bring them in upright orientation, and connect them to other pieces so as to form stands. To this end the stand building equipment may comprise a mousehole through which the stand may be gradually lowered while it is made up until the lowermost end of the stand is at the lowermost level of the setback area 1812, while the uppermost end of the stand is below the drill floor level. The stands may then be received by pipe rackers 1891 and placed in the setback structure 1812 for future use. To this end the pipe rackers are operable to traverse across the setback area, e.g. in the direction parallel to the direction connecting the well centres.
The drilling rig comprises a number of slanted chutes 1892 each for feeding pipes from the setback area 1812 to one of the well centers. To this end the drilling rig may comprise one chute for each well center position, i.e. either the fixed well-center positions or the positions to which a skidable well center can be moved. Alternatively, the chutes may be displacable so as to be selectively aligned with respective well centres. Each chute 1892 receives pipes from one of the pipe rackers 1891 and feed the pipes in a slanted upward direction through a corresponding slit 1785 in the drill floor towards a respective one of the well centres 3a,b, where they are picked up at their uppermost end by the corresponding hoisting system and lifted through the slit 1785 until they are vertically suspended above the corresponding well center. To this end, the drilling rig further comprises pipe handling equipment 1786 operable to guide the pipes while they are being lifted through the slit 1785. The slits 1785 are elongated and point away from the axis connecting the well centers and towards the side where the setback area 1812 is positioned. To allow for the pipes to be presented in this fashion, the driller's cabin 1534 is positioned at an elevated level above the slits 1785. One or more further pipe handling devices, such as iron roughnecks 1727, may be located between neighbouring slits and underneath the driller's cabin, e.g. such that each iron roughneck may service two well center positions.
The drilling rig comprises another storage area 1515 below the drill deck 2 and configured for storing risers in a vertical orientation. The riser storage area 1515 is located adjacent the moon pool 2122, e.g. on the side of the moon pool opposite the setback structure 1812. The risers may then be moved, e.g. by means of a gantry crane 2298 and respective chutes 2294 or other suitable pipe feeding equipment through holes 1681 in the drill deck floor. The riser feeding holes 1681 may be covered by removable plates, hatches or similar covers, as illustrated in e.g.
As the stands of tubulars and the risers are stored below the drill deck, and since the cat walk machines 1508 extend towards opposite sides from the well centers, and since the mast structure 1 is located on one side of the well centres, the drill 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. Moreover, at least parts of the setback structure 1812 may be covered by a platform 1788 so as to provide additional storage or working area.
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 utilized and structural and functional modifications may be made without departing from the scope of the present invention.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013 00303 | May 2013 | DK | national |
| 2013 70604 | Oct 2013 | DK | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/055307 | 3/17/2014 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2014/140367 | 9/18/2014 | WO | A |
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