NL2014765A

NL2014765A - Drilling installation; Handling system, method for independent operations.

Info

Publication number: NL2014765A
Application number: NL2014765A
Authority: NL
Inventors: Leonardus Aloysius Maria Van Der Hoorn Josephus; Zhang Naxin; Hendrik Teunis Zijderveld Govert; Cornelius Marinus Franciscus Rommens Mark
Original assignee: Gustomsc Resources Bv
Priority date: 2015-05-04
Filing date: 2015-05-04
Publication date: 2016-11-10
Also published as: NL2014765B1

Abstract

Drilling installation comprising a cantilever with a derrick and a drilling floor for performing drilling operations; further comprising an independent operations handling system arranged for handling equipment underneath the drilling floor independent of the drilling operations on the drilling floor, wherein the independent operations handling system comprises a handling element for cooperation with the equipment to be handled, wherein the handling element is movable in a XY-plane underneath the cantilever.

Description

Title: Drilling installation; Handling system, method for independent operations

The invention relates to a drilling installation.

Drilling installations are known for drilling of water, oil and/or gas wells on onshore or offshore locations. A drilling installations can be a mobile installation, for example a mobile offshore jack-up, or a can be a mobile installation mounted on a truck. A drilling installation can also be of a more permanent character, e.g. a permanent land based structure, or a permanent marine-based structure, such as a drilling platform. Offshore drilling installations may commonly be referred to as dribing rigs. The terms drilling installation and drilling rig may thus be used interchangeable. A drilling installation typically comprises a drilling floor. The drilling floor is the floor of the drilling installation where the activities take place during the drilbng operations. The drilling floor is typically the level where handling and connecting of tubulars or drill strings for drilbng takes place. The drilbng floor comprises a hole through which drib strings travel downwards into the earth bottom. Above the drilbng boor a derrick may be positioned from which the drib strings may hang off to be lowered through the hole in the drilling boor towards the earth. The drib strings may be pipes of a certain length which are to be assembled to form a continuous drib pipe that can be inserted into the earth bottom. The drib strings are assembled at the drilbng boor. There is a lot of activities as web as equipment on the dribing boor, in particular during drilbng operations. It is a hazardous area as there is being worked with heavy equipment, with dribing buids and above an oil or gas web. The dribing boor is generally known as one of the most dangerous areas for workers on the dribing installation.

The use of a drilling installation is rather expensive, so during development of an oil or gas field, there is an aim of drilling the right wells the first time. Later, during servicing of the wells, there is an aim of performing the servicing in a limited time.

During development of an oil or gas field, multiple wells are drilled from a single location. The wells are then fanning out to spread over the oil and/or gas reservoir. In case of an offshore reservoir, the well heads can be brought together above the water level, typically at fixed permanent constructions such as a jacket 18 as shown in figure 1.

During the productive life of the wells, the wells are being serviced. This is also known as ‘well intervention operations’. Well intervention operations are carried out for example to ensure or prolong the production of the well. Well intervention operations are considered to be any operation that alters the state of the well and/or the well geometry, that may provide well diagnostics and/or that manages the production of the well. Well intervention operations are carried out with or on a drilling installation. Well intervention operations with the drilling installation or well intervention equipment are typically done on the drilling floor. Thereto, the drilling operation itself is interrupted, which is costly and time consuming. Then, the well intervention operation such as wireline operations or coiled tubing operations or braided line operations or slickline operations are performed from the drilling floor through the hole in the drilling floor to the respective well. This implies that the equipment for the well intervention operations is placed on the drilling floor itself, which may result in increased risks for the workers on the drilling floor. Also work-over operations on a well may be performed to service or maintain the well.

Well intervention operations are carried out after a well went into production and preferably during the production of the well. Temporary shutting down of the well is a complex, hazardous and expensive operation and is therefore not preferred. Well intervention operations may require equipment for performing operations such as coiled tubing, cleaning, recovering, drilling, wire line operations, monitoring, phishing etc.

Also when a well is depleted, the abandonment thereof is being carried out with a drilling installation.

Due to the high cost rate of a drilling installation as well as the hazardous operations on the drilling floor, there is an ongoing challenge in increasing the operational efficiency of the drilling installation and providing for a relative safe working environment.

There is a need for a drilling installation that obviates at least one of the above mentioned drawbacks.

Thereto, the invention provides for a drilling installation comprising a derrick and a drilling floor for performing drilling operations; wherein the drilling floor is on a cantilever extendible outside of the drilling installation and the derrick is positioned over the drilling floor, further comprising an independent operations handling system arranged for handling equipment underneath the cantilever; wherein the operations handling system comprises a handling element for cooperation with the equipment to be handled; wherein the handling element is movable in a horizontal -plane underneath the cantilever.

By providing an additional handling system underneath the cantilever simultaneous operations can be performed during drilling operations or sequential operations without interruptions. For example, during drilling operations on one well, there may be well intervention operations, such as coiled tubing or wireline operations, on another well. By providing the possibility for simultaneous operations during drilling, the efficiency in use of the drilling installation may be increased and more and/or more complex operations may be performed on the wells during a limited time frame with the drilhng installation.

Also, by providing the additional handling system, well intervention operations, work over operations or other operations may be performed underneath the cantilever without interfering with the equipment on the drilling floor. These operations can thus be performed independent of the drilling operations, and may be performed simultaneous or not simultaneous to the drilling operations.

The handling system is preferably mounted at a distance below the drilling floor, to the cantilever, as not to interfere with the drilling operations on the drilling floor and to optimally be able to perform simultaneous operations.

Further, by providing the handling system underneath the cantilever, there is no additional use made of the drilling floor. The equipment for the well intervention operations may be positioned and handled underneath the drilling floor.

Advantageously the handling system is provided with a handling element. The handling element is arranged for handling the equipment for the simultaneous operations. The handling element may be arranged for guiding independent operations equipment such as a wireline or a coiled tubing, and/or may be arranged for holding equipment such as a well intervention stack, a blowout-preventer or a Christmas tree.

By providing the handling element movable in a XY-plane underneath the cantilever, the handling system may be accommodated in the relatively limited space underneath the drilling floor. The handling system may for example be provided as a carriage running over rails underneath the drilling floor, or may for example be provided as a beam extending horizontally underneath the cantilever. Many embodiments are possible. Preferably, part of the handling system on which the handling element is provided is movable in a XY-plane, for example by means of an extendible arm, or a skiddable carriage, or hinge arm etc. The handling system is at one end connected to the cantilever and at another, free end, the handling element is provided. The XY-plane is considered to be a plane below the cantilever approximately parallel to the bottom side 17f of the cantilever. In normal use circumstances, the XY-plane may be approximately horizontally. The handling element is preferably movable in the XY-plane as to allow for a relatively large reach with a hmited vertical height of the system. The movement in the XY-plane may be translational movement, rotational movement and/or a combination thereof.

The drilling installation or drilling rig may be a jack-up platform, a fixed offshore platform, a jack-up vessel or a semi-submersible platform, or a drilling vessel, etc. Many embodiments of a drilling installation are possible.

The drilling installation is provided with a cantilever on which the drilling floor and the derrick are positioned. The cantilever typically is extendible outside of the drilling installation. A cantilever may be provided for example on a jack-up platform where it may be movable arranged above the deck floor of the jack-up platform. Also a jack-up vessel, semi-submersible drilling rig or any other drilling rig may be provided with a movable cantilever. The advantages of providing a cantilever on which the drilling floor and the derrick are provided are known in the art. For example, by providing a cantilever that is extendible outside of the drilling installation, well intervention operations or drilling operations can be performed over a jacket comprising the well heads.

Advantageously, the independent operations handling system is provided at a distance below the drilling floor that is on the top side of the cantilever. Preferably, the independent operations handling system is provided at a lower part of the cantilever having the drilling floor at its top side, such that the horizontally movable handling element may be movable in the relatively limited space available underneath the cantilever. The handling system may be connected at a bottom side of the cantilever, or the handling system may be connected at a lateral side of the cantilever, for example at an aft side or the starboard side or the port side, or the handling system may even be connected to one of the sides of the moon pool. In an embodiment, the handling system may be disconnectable from or removable mounted to the cantilever, for storage and/or maintenance. For example, a carriage as handling element may be movable over rails mounted to the bottom side of the cantilever. In another example, a horizontally movable beam, such as a telescopic beam or a knuckle beam, may be mounted to a lateral side, e.g. starboard side or port side or a moon pool side or an aft side, while the beam may be extendible underneath the cantilever to perform simultaneous operations on wells during drilling operations.

The handling element is embodied for cooperation with the equipment to be handled. The equipment may be g for example a wireline or a coiled tubing. Cooperation is then merely guiding of the wireline or coiled tubing equipment to/from a reel. The handling element may then be embodied as a guide element, such as a banana sheave that may be adjustable or not. Advantageously, the reel on which the wireline or the coiled tubing is provided may be positioned on the deck of the drilling installation which is below the cantilever or on an additional foldable deck at a stern side of the deck of the drilling installation.

The handling element may also be embodied for cooperation with equipment to be handled underneath the drilling floor, such as a blowout preventer or a Christmas tree. To that end, the handling element may be embodied as a holding element such as a lifting hook or clamping device. Equipment such as a blowout preventer or a Christmas tree typically are lifted from the deck of the drilling installation to the well head deck of the jacket. Such a hiring operation may advantageously be performed simultaneously to the drilling operation, thus saving time and costs. In an embodiment, the handling system may thus be provided with a guide element as handling element or with a holding element as handling element or with both.

In an advantageous embodiment, the handling system and/or the handling element may be adjustable in a vertical direction, i.e. in a Z- direction transverse to the XY-plane. By providing a vertically adjustable handling element and/or handling system, the vertical position of the guide element for a wireline, or a coiled tubing or the vertical position the holding element for equipment to be handled, such as a blowout preventer, or a Christmas tree, may be adjusted. Then, the blowout preventer or the Christmas tree may be lowered towards the jacket comprising the well heads. Due to the vertical adjustment, hoisting capacity and/or lifting capacity may be provided by the handling system. Alternatively, hoisting capacity may be provided by a hoisting cable that is being guided over sheaves on the handling system. A winch may be provided on the handling system.

The invention further relates to a cantilever for mounting on a drilling installation, wherein the cantilever is provided with a handling system at a lower end thereof for handling equipment independent of drilling operations, wherein the handling system comprises a handling element that is arranged for movement in a XY-plane underneath the cantilever.

The invention further relates to the handling system and to a method for performing independent operations underneath the drilling floor.

Further advantageous embodiments are represented in the subclaims.

The invention will further be elucidated on the basis of exemplary embodiments which are represented in a drawing. The exemplary embodiments are given by way of non-limitative illustration.

In the drawing:

Fig. 1 shows a perspective view of a general arrangement of a drilling installation with a cantilever with a handling system mounted to the cantilever;

Fig. 2 shows an embodiment of the handling system mounted to a lateral side of the cantilever;

Fig. 3 shows a detailed view of the handling system of Fig. 2;

Fig. 4 shows an embodiment of the handling system positioned at an aft side of the cantilever;

Fig. 5a shows a schematic side view of a cantilever reaching over a well platform and an embodiment of a handling system mounted to the aft side of the cantilever;

Fig. 5b shows a top view of Fig. 5a;

Fig. 6a shows a side view of an embodiment of a handling system mounted to a bottom side of the cantilever;

Fig. 6b shows a bottom view of the handling system of Fig. 6a;

Fig. 7a shows a schematic perspective view of an embodiment of a handling system underneath the cantilever;

Fig. 7b shows a bottom view of the handling system of Fig. 7a;

Fig. 8a shows a schematic perspective view of another embodiment of a handling system underneath the cantilever;

Fig. 8b shows a bottom view of the handling system of Fig. 8a;

Fig. 9 shows a perspective schematic view of another embodiment of a handling system;

Fig. 10 shows an alternative embodiment of a handling system having a telescopic arm.

It is noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting example. In the figures, the same or corresponding parts are designated with the same reference numerals.

Figure 1 shows a schematic perspective view of a drilling installation 1. The drilling installation 1 is here embodied as a jack-up platform. Such a drilling installation 1 is typically temporarily positioned at an offshore location where an oil and/or gas field is exploited next to a well platform 18. The drilling installation 1 may be used for drilling wells when the oil and/or gas field is being explored, and may be used for maintenance or servicing of the wells and/or for well intervention during the production hfe of the wells.

Figure 1 shows a schematic perspective view of the drilling installation 1 comprising a cantilever 17. The derrick 7 is here positioned on top of the cantilever 17. The drilling floor 8 is positioned at an upper side 17a of the cantilever 17. The cantilever 17 further has lateral sides 17b, 17c, an aft side 17d, a front side 17e and a bottom side 17f.

The moonpool 10, not visible in this figure, is provided as an opening through the cantilever 17 through which the drilling string may travel further downward towards the earth bottom. In this embodiment, the cantilever 17 is translatable with respect to the deck 5 of the drilhng installation 1 in a X-direction and a Y-direction over skidding rails 37a and 37b. In alternative embodiments, the cantilever 17 may be rotatable with respect to the deck 5 or may be extendible outside of the deck 5 of the drilling installation 1 by means of translation in the X-direction only. This drilling installation 1 is a jack-up platform having three or more legs 3 that are vertically adjustable with respect to the deck 5. The legs 3 are typically adjustable between an upper position in which the legs are extending mainly above the deck 5 and between a lower position in which the legs 3 mainly extend below the deck 5. In the upper position of the legs 3, the jackup platform 1 may be towed or may sail to an offshore location. In the lower position of the legs 3 the legs may extend into the seabottom for anchoring of the jack-up platform 1. In the embodiment of figure 2, the legs 3 are in the lower position and the deck 5 is above the waterline 6.

The drilling floor 8 is the level where drilhng operations, take place. It is also the level where handling and connecting of tubulars or drill strings is done. The tubulars are pipes with a standardized and/or predetermined length that are connected to each other to form a continuous drill string that can be lowered into the seabed for drilhng a weU. The drilhng floor 8 is provided with a hole, not shown here, through which the drill string may travel downwardly into the earth bottom. Other equipment and/or installations that may be present on the deck 5 are not shown here.

Typically, for the exploration and/or production of an oil and/or gas field, multiple wells are drilled from a single location. The wells may fan out to spread over the reservoir. Therefore, multiple well strings 11 may be present. At an upper end of a well string 11, usually a well head is provided, not shown here. The well heads may be positioned above the water level on the production platform, a so-called surface wellhead, or may be positioned on the sea bed below the water level, a so-called subsea wellhead. Servicing, maintenance and/or well intervention operations during the production life of the well, take place via the wellhead.

At a level below the drilling floor 8, here mounted to the cantilever 17, a handling system 12 is provided. The handling system 12 is arranged for performing operations independent of the drilling operations on the drilling floor 8. The handling system 12 can handle equipment underneath the drilling floor 8 for example for maintenance or well intervention operations. The handling system 12 is provided with a handling element 13. The handling element 13 can be a guide element for guiding a wireline or a slackline or a coiled tubing etc. The handling element 13 may also be embodied as a cooperation element configured for cooperation with equipment to be handled. Such equipment may be a blowout preventer or a Christmas tree or a reel etc. The handling element 13 can thus be embodied as a lifting hook or a clamping mechanism.

As is widely known in the field of drilling, the drilling floor 8 is a hazardous area. There is being worked with heavy equipment, rotating machinery and dangerous fluids. Also, the drilling floor 8 is usually crowded with workers, drilling equipment, tubulars and/or drill string etc. Therefore, when maintenance or well intervention operations are to be performed, the drilling operations are interrupted and additional maintenance or well intervention equipment is being placed on the drilling floor. This is time consuming and may increase the risks on injuries and/or failures. By providing a handling system 12 mounted to the bottom side 17f or a lateral side 17b, 17c, or an aft side 17d of the cantilever 17, i.e. at a level below the drilling floor 8, maintenance and/or well intervention operations may be performed independent of the drilling operations. For example, the maintenance and/or well intervention operations may be performed simultaneously with the drilling operations, so the drilling operations does not need to be interrupted. Or, the maintenance and/or well intervention operations may be performed at the level below the drilling floor 8, even when there are no drilling operations, so there is no or limited interference of equipment and/or activities on the drilling floor 8. By separating these maintenance and/or well intervention operations from the drilling operations on the drilling floor, safety may be increased.

In the embodiment of figure 1, the handling element 13 is holding a coiled tubing unit 27, which is equipment that may be used for well intervention operations.

The handling element 13 of the handling system 12 is movable in a XY-plane underneath the drilling floor. Normally, such an XY-plane is approximately parallel to the bottom side 17f of the cantilever, at a level below the drilling floor 8. By providing the XY-movement, the handling system 12 can operate in the sometimes limited space that is available underneath the drilling floor 8. The handling element 13 and/or handling system 12 may be movable in the XY-plane, but the movement may be a translational and/or a rotational movement.

The drilling installation or here, jack-up platform, 1 is positioned adjacent a jacket or well platform 18. The well platform 18 comprises multiple wellheads 19 from which well strings 11 travel downwards to the wells. For drilling, maintenance, servicing and/or well intervention operations, the cantilever 17 may extend outside of the deck 5 over the well platform 18.

At a level below the drilling floor 8, a handling system 12 is provided with a horizontally movable handling element 13. Here, the handling system 12 is connected to a lateral side of the cantilever 17, while the horizontally movable handling element 13 is extendible underneath the cantilever 17. The handling system 12 is here embodied as a telescopic beam that is via a slewing gear 21 rotatable connectable to the cantilever 17.

From the slewing gear 21 an upwardly extending connection arm 22 is provided. By providing a rotational joint, e.g. a slewing gear 21, and a horizontally extendible arm, e.g. a telescopic beam 20, a relatively large range can be obtained for the handling element 13. A more detailed view of an embodiment of a telescopic beam 20 is given in figure 10. The telescopic beam 20 has an arm 20a that is translatable inside or outside of the arm 20b. At an end of the arm 20a the handling element 12 is provided, here as a lug. On the arm 20b a slewing gear 21 is provided such that the arm 20b is rotatable around a Z-axis, a direction transverse to the XY-plane in which the telescopic beam 20 is movable. From the slewing gear 21 upwards a connection arm 22 is mounted that provides for the connection with the drilling installation 1, e.g. with a side of a cantilever 17 on the drilling installation 1.

The handling element 13 is provided at the free end of the telescopic beam 20 and comprises in the embodiment of figure 1 a banana sheave 23 and a holding connection 24. Via the banana sheave 23, that can be adjustable in position itself, a wireline or coiled tubing or slackline or any other fine or cabling 25 can be guided towards a well head 19 on the well platform 18. The line or cabling 25 typically is reeled onto a reel 26 that is preferably positioned on the deck 5 of the drilling installation 1. In an alternative position, the reel 26 may be positioned on a foldable texas deck 28 at a side of the platform deck 5. Various positions of the reel 26 on the deck 5 may be possible.

The handling element 13 here comprises a holding connection 24 to hold equipment 27, such as a well intervention stack, blowout preventer, a coiled tubing unit, or Christmas tree, while moving the equipment to and/or from the well platform 18. Such equipment 27 can be positioned on the platform 1 to be picked up by the handling system 12 and to be hoisted to the well platform 18. To that end, for example a texas deck 28 or foldable deck or other access platform can be provided. Here, a texas deck 28 is provided at an aft side of the jack-up platform 1. The deck 28 can be folded towards the side when it is not needed. The equipment 27 can be lowered onto the texas deck 28 by means of a crane available on the deck 5. Various embodiments are possible for the holding connection 24, for example a lifting hook, or a clamping mechanism, or a plate connection etc.

By providing the handling system 12, non-drilling operations such as servicing, maintenance, well intervention, work over etc. may be performed independent of the drilling operations. The drilling operations therefore do not need to be interrupted when such operations are being performed. Simultaneous operations to the drilling operations may become possible. This may provide for a more safe work environment as well as a more efficient use of the drilling installation. Eventually, the time the jackup drilling installation 1 may be required for a specific well platform may be reduced.

The handling element 13 is horizontally movable to provide an optimal reach over the well platform and to position handling element 13 above a determined well head in order to be able to perform independent operations on that well. Advantageously, the reach of handling element 13 is larger than the moonpool area 10 to cover as much well heads on the well platform 18 as possible.

By providing a horizontally movable handling element 13 and/or handling system 12, the handling system 12 may be stored underneath the cantilever, or may be operable underneath the cantilever. Alternative embodiments such as a segmented beam, or a knuckle beam, or a drivable carriage are shown in figures 3, 5, 6, 7 or 8.

Figure 2 shows a more detailed perspective view of the handling system 12 mounted to a lateral side of the cantilever 17, for example a starboard side or a port side, or an aft side. An advantage of mounting the handling system to the port or starboard side of the cantilever 17 may be that, when retracting the cantilever, the handling system 12 can come above the deck 5. There, the handling system 12 may disconnected from the cantilever 17 for storage on deck 5 or for maintenance.

Here, the handling system 12 is embodied as a segmented beam 20 having a first arm 14 and a second arm 15 that are hingedly connected to each other such that the handling element 13 at the free end 12b is movable in a horizontal plane. Here, the segmented beam 20 comprises two hingedly connected arms, but may also comprise three or more hingedly connected arms. Also, the handling system 12 may be a hybrid structure comprising of hingedly connected arms of which one arm may be embodied as a telescopic beam. The hinge joint may be provided by slewing gears or may be actuated by hydraulic cyhnders.

In the embodiment of figure 2, the holding connection 24 of the handling element 13 is connected to a well intervention stack 27 that is positioned on the texas deck 28 for being hoisted to the platform 18. For positioning the equipment 27 onto the platform 18, it is advantageous that the handling system 12 is adjustable in the Z-direction and/or that lifting capacity is available on the handling system 12. The arms 14, 15 may be movable in the XY-plane to position the handling element 12 holding e.g. the well intervention stack or guiding e.g. the wireline to a position in accordance with the determined well, e.g. the well head of the well to be serviced or on which well intervention operations are to be performed. This position can be a position above the determined well head. Then, to lower the well intervention stack towards the well head, it is advantageous that the handling system 12 is adjustable in the Z-direction. By then adjusting the vertical position of the handling system 12, for example by means of hydraulic cylinders, the well intervention stack, or similar equipment, can be lowered and placed onto the well platform 18.Two hydraulic cylinders 29 are connected to the connection arm 22 to adjust the height of the connection arm 22 with respect to the cantilever 17. As such, the vertical position of the handling system 12 may be adjusted in a range provided by the strokes of the hydraulic cylinders 29. To guide the vertical movement of the connection arm 22, two sliding bushes 30 are provided. In an embodiment, the lifting capacity may be provided by the hydraulic cylinders 29 as well. In another embodiment, a hoisting cable running over sheaves on the handling system 12 may be provided. The sliding bushes 30 may also provide for relative easy disconnection of the connection arm 22 and the handling system 12 with the cantilever 17. As such, the handling system 12 can be disconnected from the cantilever 17 and stored on the deck 5, for example during sailing and/or towing of the jack-up platform 1, or for maintenance purposes on the handling system 12.

For example, the well intervention stack 27 may be connected to the lifting hook 24 of the handling element 13 and may then, by movement of the handling element 13 in the horizontal XY-plane be positioned above the determined wellhead 19 of the well jacket 18. Then, the hydraulic cylinders 29 may be operated to lower the connection arm 22 and thus the handling system 12 with the connected equipment 27 towards the well jacket 18.

Figure 3 shows the handling system 12 in a storage position at a lateral side of the cantilever 17. The handling system 12 is here too embodied as a segmented beam having a first beam 14 with the handling element 13 at its end and a second beam 15 connectable to the cantilever 17 via the slewing bearing 21 and the connection arm 22. The beams 14 and 15 are hingedly connected to each other via a slewing gear, but other hinge joints may be provided as well. Alternatively, the rotational movement between the two beams may be activated by hydraulic cylinders. The two cylinders 29 that are connected to the connection arm 22 may provide for vertical adjustment of the handling system 12 over the stroke of the cylinders. Alternatively and/or additionally, lifting capacity may be provided by the cylinders 29 and/or by a hoisting system 31 comprising a hoisting cable 32 running from winch 33a over sheaves 33b on the handling system 12. In this embodiment, the banana sheave 23 for guiding wires and/or cabling from a reel on the deck 5 to the well platform is adjustable by means of cylinders 34.

Figure 4 shows the handling system 13 connected to the aft side 17d of the cantilever 17. The lifting capacity for lifting the equipment 27 is in this embodiment as well provided by a hoisting cable 32 running from winch 33a over sheaves 33b. Here, the handling element 13, the lifting connection 24 and/or the banana sheave 23, is horizontally movable together with the first beam 14 and the second beam 15 of the handling system 12 when the handling system 12 is operated to bring the equipment to the determined position. Once at the determined position, the equipment 27, here together with the lifting connection 24 is lowered to the well platform 18 by means of the hoisting system 31. By using the hoisting system 31, not the whole handling system 12 is vertically adjustable, but only the handling element 13. Typically, the positioning in the XY-plane may be done first, then the height in vertical direction may be adjusted when required. To enable independent operations, such as well intervention operations, a guide element 23 for guiding the wireline 25 from the reel 26 may be sufficient. Then, positioning of the handling element 13, and thus of the handling system 12, in the horizontal XY-plane, may allow for providing a relatively large reach over the well platform 18.

Figures 5a and 5b give an alternative embodiment of a handling system 12 at the aft side 17d. Here, the handling system 12 comprises a first beam 14 and a second beam 15 hingedly connected to each other by which the hinge joint is actuated with a hydraulic cylinder 38.

Figures 6a and 6b and figures 7a and 7b show alternative embodiments of a handling system 12 mounted to the bottom side 17f the cantilever 17. The handling system 12 is provided as a carriage 39, that is movable over a ring-shaped rail 35. The rail 35 is arranged around the moonpool 10 so that operations through the moonpool 10 do not have to be interrupted. The carriage 39 is movable over the rail, and as such movable in a XYplane below the cantilever 17. In the embodiment of figures 6a and 6b, carriage 39 is provided with an extension arm 40, e.g radially movable with respect to the carriage 39, extending the reach of the handling system 12 Further, a hoisting system 31 with sheaves 33 can be provided mounted onto the carriage for hoisting equipment. The handling element 12 may be provided at an end of the extension arm 40, as in figure 6a, or may be provided on the carriage 39. Alternative to a ring-shaped rail an XY-skidding system 36 may be provided configured around the moonpool 10, as embodied in figures 8a and 8b. The handling element 13 can thus be positioned at determined positions reachable by the XY-skidding system.

Figure 9 shows an alternative embodiment of the handling system 13, mounted to the aft end of the cantilever 17. The handling system 13 is here a segmented beam 20 having a first arm 14 and a second arm 15 hingedly connected to each other and actuatable with respect to each other by means of cylinders. The first arm 14 is here embodied as a bend beam which may allow for a relatively larger reach than with a straight first arm. The handling system 12 is via a slewing gear 21 and a connection arm 22 connected to the cantilever 17.

For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

It may be understood that the embodiments shown have the same or similar components, apart from where they are described as being different.

For example, it may be understood that the handling system as described above may have various embodiments as well as combinations of elements of these embodiments. Also, it may be understood that the handling system may be positioned at a lateral side or at an aft side or at a bottom side of the cantilever, irrespective of the embodiment of the handling system.

In the claims, any reference signs placed between parentheses shall not be construed as hmiting the claim. The word ‘comprising’ does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different, claims does not indicate that a combination of these measures cannot be used to an advantage.

Many variants will be apparent to the person skilled in the art.

All variants are understood to be comprised within the scope of the invention defined in the following claims.

Claims

A drilling rig comprising a derrick and a drilling floor for performing drilling operations, wherein the drilling floor is on a cantilever which is extendable outside the drilling installation and the derrick is placed above the drilling floor; further comprising - an independent operation handling system adapted to handle equipment under the cantilever independently of the drilling operations on the drilling floor; - wherein the independent operation handling system comprises a handling element for cooperation with the equipment to be handled; - wherein the handling element is movable in an XY plane below the cantilever.

2. Drilling rig as claimed in claim 1, wherein the handling system comprises a horizontally movable arm with the handling element at a free end of the arm.

3. Drilling rig as claimed in claim 1 or 2, wherein the handling element is adapted for handling equipment such as a wire line and / or coiled tubing, for example as a banana sheave.

4. Drilling rig as claimed in any of the foregoing claims, wherein the handling element is configured for holding equipment, such as a borehole intervention stack, a blowout preventer and / or a Christmas tree, for example as a lifting hook or a clamping mechanism.

Drilling rig according to claim 4, wherein the handling system and / or handling element is further adapted for movement in the Z direction.

A drilling rig as claimed in claim 4 or 5, wherein the handling system is further provided with lifting means.

Drilling rig as claimed in any of the foregoing claims, wherein the handling system is mounted on a bottom and / or a side of the cantilever.

A drilling rig as claimed in any one of the preceding claims, further comprising a reel on the deck of the drilling rig facing the handling system, wherein the reel is adapted to include equipment such as a wire line or coiled tubing for handling by the handling system.

9. Drilling installation as claimed in any of the foregoing claims, further comprising an equipment station on one side of the drilling installation directed towards the handling system, for instance arranged as a foldable texasdeck.

10. Drilling rig as claimed in any of the foregoing claims, wherein the handling system is removably connected to the cantilever for storage on the drilling rig during non-use of the handling system.

A cantilever for mounting on a drilling rig, wherein the cantilever is provided with a handling system at its lower end for handling equipment independent of drilling operations, the handling system comprising a handling element adapted to move in an XY plane below the cantilever.

A handling system adapted for mounting on a cantilever for handling equipment below the cantilever, comprising a handling element for cooperating with the equipment, the handling element being adapted for movement in an XY plane.

The handling system of claim 12, wherein the handling system comprises a segmented beam extending in the XY plane, the handling element being arranged on a free end of the segmented beam.

The handling system of claim 13, wherein an end of the segmented bar opposite the free end is connectable to the cantilever.

The handling system of claim 14, wherein the connectable end is adjustable relative to the cantilever in a Z direction transverse to the XY plane.

The handling system according to claim 14 or 15, wherein the handling system can be releasably mounted with the cantilever.

A method for performing operations on wells independent of drilling operations on a drilling rig with a cantilever extendable outside the drilling rig, comprising providing a handling system for handling equipment for performing the independent operations, the handling system comprising a handling element for cooperating with the equipment, moving the handling element in an XY plane below the cantilever to a position corresponding to a particular well head.

The method of claim 17, further moving the handling system and / or handling element down in a Z direction for lowering equipment, such as a well bore intervention stack or a blowout preventer to the particular well head.