Offshore drilling vessel and method

Abstract

An offshore drilling vessel includes a floating hull subjected to heave motion. The hull includes a moonpool and a drilling tower near the moonpool. A drilling tubulars storage rack is provided for storage of drilling tubulars. The vessel includes a heave motion compensation support that is adapted to support a slip device whilst performing heave compensation motion relative to the heaving motion of the vessel. A racking device is provided with a heave motion synchronization system that is adapted to bring a tubular retrieved from the storage rack in heave motion into a vertical motion that is synchronous with the heave compensation motion of the string slip device. The racking device includes vertical rails and at least two separate motion arm assemblies mounted on said vertical rails. Each separate motion arm assembly includes its own vertical drive which is electrically connected to the heave motion synchronization system.

Claims

1. An offshore drilling vessel, the vessel comprising: a floating hull subjected to heave motion, the hull being provided with a moonpool; a drilling tower at or near the moonpool; a drilling tubulars storage rack adapted for storage of drilling tubulars; a tubulars string slip device, the slip device is adapted to support the weight of a tubulars string suspended therefrom along a firing line; a support that is adapted to support said slip device; a racking device that is adapted to move a tubular between the storage rack and a position in the firing line above the tubulars string slip device in order to allow for making a connection between a new tubular and the suspended tubular string or the removal of a tubular from the tubular string during tripping comprising: a motion system, including a controller that is adapted to bring a tubular retrieved from the storage rack into a vertical motion towards the tubulars string slip device, thereby allowing for the connection of the tubular to the suspended tubulars string; a vertical rail; at least two separate motion arm assemblies mounted on said vertical rail, wherein each of the at least two motion arm assemblies comprises: an own base that is vertically mobile along said vertical rail by a vertical drive including a motor, the vertical drive is positioned on said base; and a motion arm connected to said base, the motion arm of at least one of the at least two arm assemblies being provided with a tubular gripper member connected to said arm, wherein each motor of the vertical drive of each of the at least two motion arm assemblies is electrically connected to the controller of the motion system, wherein each vertical drive of each individual motion arm assembly comprises an own dedicated hydraulic power unit (HPU) including a pump driven by the motor, a tank, and valves, wherein said hydraulic power unit is connected to the controller by at least one umbilical cable, and wherein one end of the at least one umbilical cable is connected to the controller at a fixed position on the floating hull and the other end is connected to the hydraulic power unit on board of the motion arm assembly.

2. The vessel according to claim 1, wherein the umbilical cable is looped around a cable length compensating device including a counterweight, to compensate a varying length of the umbilical cable in between the controller and the hydraulic power unit.

3. The vessel according to claim 2, wherein the cable length compensating device is positioned inside a mast inner space.

4. The vessel according to claim 2, wherein the motor is connected with a supercapacitor which allows a temporary storage of electricity.

5. The vessel according to claim 3, wherein the motor is connected with a supercapacitor which allows a temporary storage of electricity.

6. The vessel according to claim 2, wherein the motor of the hydraulic power unit is positioned at a distance away from said gripper member, such that the motor is positioned outside an Ex-zone.

7. The vessel according to claim 1, wherein the motor is connected with a supercapacitor which allows a temporary storage of electricity.

8. The vessel according to claim 1, wherein the motor of the hydraulic power unit is positioned at a distance away from said gripper member, such that the motor is positioned outside an Ex-zone.

9. The vessel according to claim 1, wherein the drilling tower comprises a mast, and wherein a side of the mast facing the moon pool is provided with two racking devices each comprising at least two motion arm assemblies in a substantially mirrored symmetry.

10. The vessel according to claim 1, wherein the vertical rail comprises a vertical toothed rack, with each mobile base having one or more motor driven pinions engaging said toothed rack.

11. The vessel according to of claim 10, wherein the vertical rail comprises a vertical guide rail onto which corresponding guide members of the base of each motion arm assembly engage, wherein the vertical toothed rack is arranged parallel to said vertical guide rail, and wherein the base of the motion arm assembly is provided with one or more pinions engaging said vertical toothed rack, the base being provided with one or more motors driving said one or more pinions.

12. The vessel according to claim 10, wherein the toothed rack is vertically mobile so as to perform a heave compensating motion, when connected to a dedicated vertical drive of the toothed rack or when connected to another component that is or can be brought in heave compensation motion, to a heave compensated working deck or a travelling block of heave compensated drawworks.

13. The vessel according to claim 1, wherein the vessel comprises an iron roughneck device, the roughneck device is independently supported with respect to the floating hull by an iron roughneck support device, which is a mobile motion arm assembly including a base which is movable along the vertical rail.

14. The vessel according to claim 1, wherein the motion arm is a telescopic extensible arm, the arm having a first arm segment which is connected to the base via a vertical axis bearing allowing the motion arm to revolve about said vertical axis, said vertical axis forming the only axis of revolution of said arm, and wherein said arm comprising one or more telescoping additional arm segments.

15. The vessel according to claim 14, wherein the motion arm is connected to the base via a horizontal axis bearing allowing the motion arm to revolve about a horizontal axis to provide a pivoting in up and down motion, such that at least some of the motion required to obtain the vertical motion can be derived from said pivoting.

16. The vessel according to claim 1, wherein the storage rack is a rotary storage rack which is rotatable mounted on the vessel.

17. The vessel according to claim 1, wherein the vessel comprises: a drill string main hoisting device comprising: a main hoisting winch and main cable connected to said winch; and a travelling block suspended from said main cable, which travelling block is adapted to suspend a drill string therefrom along a drilling firing line, with an intermediate topdrive adapted to provide a rotary drive for the drill string; and a drill string heave compensation system adapted to provide heave compensation of the drill string.

18. The vessel according to claim 1, wherein the vessel is provided with a mobile working deck and with a dedicated working deck heave compensation system adapted to provided heave compensation motion of the working deck.

19. A method for drilling a subsea wellbore, wherein use is made of a drilling vessel according to claim 1, and wherein the method involves, with the slip device supporting a suspended tubulars string and being in motion relative to the hull of the vessel: retrieving a tubular from the storage rack with the racking device; bringing the retrieved tubular in a vertical motion pattern relative to the hull of the vessel that is synchronized with the motion of the slip device, as well as moving the tubular into the firing line above the slip device; and connecting the tubular to the tubulars string suspended from the slip device.

Description

(1) In the drawings:

(2) FIG. 1 shows an example of an offshore drilling vessel according to the invention in vertical cross-sectional view,

(3) FIG. 2 shows a more detailed view of the drilling side of the mast,

(4) FIG. 3 shows the drilling side of the mast as well as parts of the hull,

(5) FIG. 4 shows the drilling side of the mast and storage carousels with the working deck in heave compensation motion,

(6) FIG. 5 shows a detail of the situation of FIG. 4,

(7) FIG. 6 illustrates an upper portion of the riser in FIGS. 4 and 5, including a slip joint in locked and collapsed position,

(8) FIG. 7A shows in a perspective view a base of the motion arm assembly;

(9) FIG. 7B shows in a top view the base of FIG. 7A together with a vertical rails;

(10) FIG. 7C shows in a perspective view a motion arm of the motion arm assembly;

(11) FIG. 7D shows in a top view an assembly of the base, rails and motion arm out of FIG. 7A-7C;

(12) FIG. 8 shows in a top view a mounting of a left-hand and right-hand version of the motion arm to the base;

(13) FIG. 9A shows in a perspective view a racker assembly of the system of FIG. 2;

(14) FIG. 9B shows the racker assembly of FIG. 9A in a side view, partly as wire frame,

(15) FIG. 9C shows the racker assembly of FIG. 9A in a top view,

(16) FIG. 10 illustrates the handling of a tubular by means of the racker assemblies with the lower assembly supporting an iron roughneck device; and

(17) FIG. 11 shows in a schematic view a suspension of a group of electrical cables extending in parallel around umbilical pulley towards several motion arm assemblies.

(18) As shown in FIG. 1, the vessel 1 here is a monohull vessel having a hull 2 subjected to heave motion. The hull has a moonpool 5 extending through the hull, here with a waterline within the moonpool. In an embodiment as semi-submersible vessel the moonpool may be arranged in an above waterline deck box structure that is supported by columns on one or more pontoons, e.g. a circular pontoon in case an arctic design of the vessel is envisaged.

(19) A drilling tower, here mast 4 is mounted on the hull, here above the moonpool 5. The mast 4 is associated with hoisting means, in the art called drawworks, in the shown embodiment forming two firing lines 6, 7 along and on the outside of the mast, here fore and aft of the mast 4, that extend through the respective fore and aft portions 5a, 5b of the moonpool 5.

(20) The firing line 6 is designed for performing drilling, and here includes a drill string rotary drive, here a top drive 17 or other rotary drive, adapted for rotary driving a drill string.

(21) As shown in further detail in FIGS. 2 and 3, a movable working deck 25 is provided, having a well center or opening 27 therein through which a drill string passes, along the firing line, here firing line 6.

(22) The vessel 1 is equipped with two drilling tubulars rotary storage racks 10, 11 adapted to store multiple drilling tubulars 15 in vertical orientation, preferably multi-jointed tubular stands.

(23) Preferably, each drilling tubulars rotary storage rack is rotatable mounted on the vessel so as to rotate about a vertical axis.

(24) As is known in the art each drilling tubulars rotary storage rack 10, 11 includes slots for the storage of multiple tubulars in each drilling tubulars rotary storage rack in vertical orientation. As is known in the art the racks 10, 11 here include a central vertical post and multiple disc members at different heights of the post, at least one disc being a fingerboard disc having tubulars storage slots, each slot having an opening at an outer circumference of the fingerboard disc allowing to introduce and remove a tubular from the storage slot. It is envisaged that in a preferred embodiment the tubulars rest with their lower end on a lowermost disc member. In the example shown it is envisaged that triple stands are stored in the racks 10, 11. The diameter of each rack 10, 11 is about 8 meters.

(25) Drive motors are present for each of the first and second drilling tubulars rotary storage rack 10, 11 that allow to rotate the drilling tubulars storage rack about its vertical axis.

(26) As shown in FIG. 3, the vessel 1 also includes a horizontal catwalk machine 80 on the deck and aligned with the relevant firing line and allowing to bring tubulars from a remote position towards the firing line or to a stand-building location, e.g. from hold for horizontal storage of drilling tubulars in the aft portion of the hull and/or the deck storage.

(27) The vessel 1 also includes a driller's cabin 85 on a drillers cabin deck 86.

(28) At the side of the mast 4 facing the vertically mobile working deck 25 two tubular racking devices 140 and 140′ are mounted, each at a corner of the mast 4. If no mast is present, e.g. with a latticed derrick, a support structure can be provided to arrive at a similar arrangement of the racking devices 140 and 140′ relative to the deck 25 and well center 27.

(29) As is preferred each racking device 140, 140′ has multiple, here three motion arm assemblies. Here a lower first racker motion arm assembly 141, 141′, a second racker motion assembly 142, 142′, operable at a greater height than the first tubular racker assembly, and a third well center tool motion arm assembly 143, 143′.

(30) Each set of motion arm assemblies is arranged on a common vertical rails 145, 145′ that is fixed to the mast 4, here each at a corner thereof.

(31) In FIG. 6, as can be better seen in the depiction of FIG. 10, a drill pipe multi-joint tubular 15 is held by racker assemblies 142′ and 141′ in the firing line above the well center 27, thereby allowing to connect the tubular 15 to the drill string supported, e.g., by drill string slip device 30 in or on the deck 25. Each of said assemblies 142′ and 141′ carries a tubular gripper member 142′t and 141′t at the end of the motion arm of the assembly. Instead of both assemblies carrying a gripper member it is also possible that only one arm is provided with a gripper member that supports the weight of the gripped tubular and the other arm carries a centralizer that holds the tubular in the upright position.

(32) As shown in FIG. 5, the lower motion arm assembly 143 of the racking device 140 carries an iron roughneck device 150, here with a spinner 151 thereon as well.

(33) FIG. 7A-7D show the motion arm assembly 141 in further detail. FIG. 7A shows a base 141b of the motion arm assembly. The base 141b forms a sub-assembly which can be assembled together with a motion arm as shown in FIG. 7C. The base 141b is configured to allow different configurations of the motion arm assembly, in particular a left and right configuration.

(34) As shown in FIGS. 7A and 7B, the base 141b comprises a flange at a bottom region which is provided with two pairs of mounting holes and connector pins 156. At a top region, the base 141b further comprises mounting holes and pins which correspond with the respective first and second pair of mounting holes at the bottom region. Each pair of mounting holes of the base 141b corresponds with a pair of mounting holes of the arm assembly as shown in FIG. 7D and FIG. 8.

(35) As shown in FIG. 8, the first pair of mounting holes is provided to obtain a left-hand attachment “L” of the motion arm, the second pair of mounting holes is provided to obtain a right-hand attachment “R” of the motion arm (illustrated by a dashed lines in FIG. 8).

(36) A suspension beam 157 is provided to connect the motion arm to the top region of the base 141b. The suspension beam 157 comprises two legs. The two legs of the suspension beam 157 diverge in a direction away from the base 141b. A proximal end of each leg is connected to the base 141b, and a distal end is connected to the motion arm. The distal end of the suspension beam 157 is substantially positioned at a center of gravity of the motion arm. In particular, the distal end of the suspension beam 157 is connected at a position of the vertical axis bearing 147. Herewith, the suspension beam 157 contributes to an optimal dynamic behavior of the motion arm assembly in that a weight of the motion arm is substantially compensated in its center of gravity.

(37) As can be seen in FIGS. 9A-9C the motion arm 141m is here embodied a telescopic extensible arm, the arm having a first arm segment 141m-1 which is connected to the base 141b via a vertical axis bearing 147 allowing the motion arm 141m to revolve about this vertical axis. As is preferred this vertical axis forms the only axis of revolution of the motion arm. The motion arm has two telescoping additional arm segments 141m-2 and 141m-3, with the outer arm segment being provided with a connector 148 for a tubular gripper 141′t and/or a well center tool (e.g. iron roughneck device 150).

(38) The telescopic arm is rotatable from a neutral position, as illustrated in FIG. 7D, in a clockwise direction across angle α and in a counterclockwise direction across angle β. In the neutral position, the telescopic arm—seen in a top view—extends in a direction in parallel with a roll axis of the vessel. The telescopic arm is rotatable across the angle α to grip a tubular from a storage rack 10. The telescopic arm is rotatable across the angle β to bring the gripped tubular to the firing line 6. The vertical axis bearing 147 is positioned with respect to the base 141b, such that the angle α extends from the neutral position to at least 70°, in particular at least 90°, more in particular at least 100° and the angle β extends from the neutral position to at least −70° in particular about 90°. Herewith, the telescopic arm may have a compact configuration with an optimal reach.

(39) In FIG. 2 reference numeral 55 depicts a well center tools storage structure that is adapted to store therein the one or more well center tools, e.g. an iron roughneck device 150, 150′ that are connectable to the motion arm of the lowermost motion arm assembly 143, 143′, As preferred one such storage is present at each side of the moonpool.

(40) As visible in FIG. 9B, in the example shown a hydraulic cylinder 152 is present between first and second segments of the arm, and a further cylinder 153 between the second and third segments of the arm. Each cylinder 152, 153 is operable to cause extension and retraction of the arm. For example the racker assembly is provided with a self-contained hydraulic unit 154 including an electric motor driven pump, a tank, and valves.

(41) In FIGS. 2-4 and 10 it can be recognized that each tubular racking device comprises a vertical guide rail 145, 145′ onto which corresponding guide members of the base 141b of each tubular racker assembly engage. As shown in FIG. 9C, in this example the base 141b carries four sets of each three rollers 149 of which two rollers 149 ride along opposed faces of a flange of the rails 145 and one roller rides along a lateral side of the flange.

(42) As shown in FIGS. 7B and 9, the racking device 140 further comprises a vertical toothed rack 160 arranged parallel to this vertical guide rails 145. Here the toothed rack 160 is mounted on the rail 145, here on a front plate of the rail between the two flanges of the rail 145.

(43) The base 141b of the tubular racker assembly 141 is provided with one or more, here two, pinions 161 engaging with this vertical toothed rack 160. The base is provided with one or more motors 162, here two, driving the pinions, so as to allow for a controlled vertical motion of the racker assembly 141.

(44) As is preferred the one or more motors 162 driving the one or more pinions 161 are electric motors. In an embodiment a supercapacitor 201 is included in an electric power circuit feeding said one or more vertical motion motors, which allows the temporary storage of electricity that may be generated by said one or more motors during a downward motion of the assembly. This energy can then be used for the upward motion again.

(45) In view of a reduction of the number of parts it is preferred for all motion arms to be identical, so that limited spare parts are needed. For example a single complete motion arm, or a single complete racker assembly is stored aboard the vessel.

(46) As shown in FIG. 9B, in view of reduction of the number of parts it is preferred for the vertical axis bearing 147 between the base 141b and the motion arm 141m to be arranged in a bearing housing 147a that is releasable attached to the base 141b of the racker assembly. As depicted in FIG. 8 here the base 141b provides both a left-hand attachment position “L”, as indicated in FIG. 7D, and a right-hand attachment position “R”, as shown in use in FIG. 9A, for the bearing housing 147a which allows to use the same base in each of the racking devices 140 and 140′. As is preferred and shown in FIG. 8, the attachment positions are formed by elements on the base having holes therein and the housing 147a having mating holes therein, so that one or more connector pins 156 can be used to secure the housing to the base.

(47) As shown in FIG. 10 the motion arm assembly 143 holds iron roughneck device 150 above the well center for make-up or breaking up of connections between tubulars in the firing line 5. At the same time the other motion arm assembly 143′ can be equipped with a second iron roughneck device, which is then already prepared for handling different diameter tubulars.

(48) Should e.g. assembly 141′ fail to operate, its task can be taken over by assembly 143′ on the same rails 145′ as it may be quickly equipped with a tubulars gripper and brought to the level appropriate for tubulars racking. For example the assembly 141′ is then raised to make room for the assembly 143′.

(49) The vessel comprises an electrical heave motion compensation controller 200, e.g. a computerized controller linked to a system detecting heave motion. This controller 200 is linked to the vertical drive of the bases of the vertically mobile motion arm assemblies.

(50) The heave motion controller 200 provides to these one or more vertical drives, e.g. to the pinion driving motors, a control signal representing a heave compensation motion of the one or more motion arm assemblies. This allows to obtain heave motion compensation of the tubular gripper or well center tool held by the respective motion arm.

(51) This embodiment is, for example, of use in combination with a heave motion compensated working deck, e.g. as disclosed in WO2013/169099. For example a motion arm assembly can then be employed to hold a component of a coiled tubing injector device in a position above the well center whilst the drill floor is in heave compensation mode. Of course other heave motion compensation arrangements of the drill floor can also be envisaged in combination with the present invention.

(52) The depicted embodiment all motion arm assemblies are connected to the electrical heave motion compensation controller 200, allowing all operations thereof to be done whilst performing heave compensation motion, e.g. in conjunction with a heave motion performing working deck 25.

(53) FIG. 11 shows in a schematic view an electric power supply 170. The electric power supply 170 is connected to the controller 200 which in a first aspect of the invention can be part of the heave motion synchronization system or according to a second aspect of the invention of another motion system. The electric power supply 170 comprises at least one umbilical cable 171, 172 which extends from the controller 200 to the motion arm assemblies 141, 142. As shown in FIG. 11, a plurality of umbilical cables 171, 172 may be arranged in parallel to electrically connect a plurality of motion arm assemblies 141, 142.

(54) The umbilical cable 171 is an electrical cable for feeding electrical components, in particular the electric motor 162, on board of the motion arm assembly. The umbilical cable 171 extends along the mast 4. During a movement of a motion arm assembly, a length of the umbilical cable 171 along the mast 4 varies. Preferably, the electric power supply 170 comprises a cable length compensating device 176 for compensating the varying length along the mast 4. Preferably, the cable length compensating device 176 is positioned inside an inner space 4a of the mast 4.

(55) Here, the umbilical cable 171 extends upwards from the motion arm assembly to a top region of the mast 4. At the top region of the mast 4, the umbilical cable 171 is looped around a pulley 179 which is fixed in position with respect of the mast 4. The mast 4 is a hollow mast which includes a mast inner space 4a. The umbilical cable 171 extends from the fixed pulley 179 in a downwards direction into the mast inner space 4a. The umbilical cable 171 extends inside the mast inner space and is looped around at least one movable pulley 178 of the cable length compensating device 176. The pulley 178 is movable with respect to the mast 4. The movable pulley 178 serves to compensate a varying length of the umbilical cable 171 during a movement of the motion arm assembly. The movable pulley 178 comprises a counterweight 177 to maintain a certain tensile force on the umbilical cable 171 during movement of the motion arm assembly. Preferably, the movable pulley 178 and the counterweight 177 is arranged to move along a pulley distance at a bottom region of the mast 4 to contribute to a low positioned center of gravity.

(56) In an alternative embodiment, instead of the movable pulley 178 including the counterweight 177 as a cable length compensating device 176, a winch may be provided to compensate for the varying length of the umbilical cable 171 during operation.

(57) In particular when heave motion compensation mode of one or more of the mobile motion arm assemblies is envisaged, the electric power supply 170 may include a supercapacitor 201, even such a capacitor mounted on the base of each assembly itself, for temporary storage of electric energy in the downward motion and use thereof for the upward motion. Preferably, a single capacitor is used for the racking device 140, wherein the capacitor is positioned at a position which is fixed with respect to the hull 2 of the vessel 1. Preferably, the capacitor 201 is placed at the deck of the vessel.

(58) In an embodiment wherein the mobile base of each mobile motion arm assembly 141, 142, 143 engages with a pinion 161 on a vertical rack, one may provide heave motion compensation also by bringing said vertical toothed rack 160 into heave compensation motion, e.g. the toothed rack being slidable along the tower or mast 4 and with a vertical heave motion drive connected to the rail 145, 145′ or with the rail being connected to another object that is brought into heave compensation mode. For example one could envisage that the toothed rack is connected to the working deck 25, with the working deck 25 being operable in heave compensation mode so that the toothed rack follows the working deck 25.

(59) The vessel 1 does also include a main hoisting device comprising a main hoisting winch and main cable connected to said winch, and a travelling block 40 suspended from said main cable 41, e.g. with a multiple fall arrangement between a crown block 42 and the block 40. From the travelling block the tubular string 15a is suspended when the slip device 30 is released from the drill string. An intermediate topdrive 17 then provides the rotary drive for the drill string.

(60) As is preferred a drill string heave compensation system is provided to effect heave compensation of the drill string, here of the travelling block 40, e.g. in the manner as described in U.S. Pat. No. 6,595,494, where a travelling block heave compensation system comprises two main cable heave compensation sheaves, each one in the path between a main hoisting winches and the travelling block. Each of these sheaves is mounted on the rod of a compensator cylinder, with these cylinder connected, possibly via an intermediate hydraulic/gas separator cylinder, to a gas buffer as is known in the art.

(61) FIG. 6 shows the vertically mobile working deck 25 that is vertically mobile within a motion range including a lower stationary position 86, wherein the working deck is used as stationary drill floor deck with the slip joint 50 unlocked, and the motion range further including a heave compensation motion range 72 that lies higher than the lower stationary position 86. In this heave compensation motion range the working deck 25 can perform heave compensation motion relative to the hull of the vessel.

(62) For example the heave compensation motion range is between 5 and 10 meters, e.g. 6 meters. For example the average height of the working deck in heave motion above the driller cabin deck 86 with cabin 85 of the vessel is about 10 meters.

(63) The FIG. 6 further shows an upper riser section 90 that is mounted at the top of the riser and extends upward from the inner barrel 52 of the slip joint 50 at least to above the lower stationary position 86 of the working deck, preferably to the heave compensation motion range of the deck 25.

(64) A lower section member 91 here forms the rigid connection between the actual end of the inner barrel 52 and a connection cable connector 100 of a heave compensation arrangement, here with said member 91 having a collar 92 that rests on the connector 100. From said member 91 upwards a further riser member 93 extends upward to above the level 86. Above said riser member 93 equipment to be integrated with the riser top, such as preferably at least a rotating control device (RCD) 94, and a mudline connector 95 are mounted. For example other riser integrated equipment like an annular BOP 96 may be arranged here as well.

(65) With the slip joint 50 in collapsed and locked position, as here, the working deck 25 that rests on top of the riser section 90 performs a heave motion compensation motion relative to the vessel's hull as the riser is now a fixed length riser due to the locking of the slip joint 50.

(66) The described motion arm assemblies allow drilling and tripping as they are able to synchronize their vertical motion with the heave motion so that, from the standpoint of the working deck, drilling and tripping can be carried out in a proper way.

(67) Thus, the invention provides an offshore drilling vessel comprising a floating hull subjected to heave motion. The hull comprises a moonpool and a drilling tower near the moonpool. A drilling tubulars storage rack is provided for storage of drilling tubulars. The vessel comprises a heave motion compensation support that is adapted to support a slip device whilst performing heave compensation motion relative to the heaving motion of the vessel. A racking device is provided with a heave motion synchronization system that is adapted to bring a tubular retrieved from the storage rack which is in a in heave motion into a vertical motion that is synchronous with the heave compensation motion of the string slip device. The racking device comprises a vertical rails and at least two separate motion arm assemblies mounted on said vertical rails. Each separate motion arm assembly comprises its own vertical drive which is electrically connected to the heave motion synchronization system.

REFERENCE LIST

(68) TABLE-US-00001  1 vessel  4 mast  5 moonpool  5a, 5b fore and aft on the outside of the mast  6, 7 firing line  10 rotary storage rack  11 rotary storage rack  17 topdrive  25 mobile working deck  27 well center  30 slip device  40 travelling block  41 main cable  42 crown block  50 slip joint  52 inner barrel  72 heave compensation motion range  80 catwalk machine  85 driller's cabin  86 lower stationary position  90 upper riser section  91 lower section member  92 collar  93 riser member  94 rotating control device  95 mudline connector  96 BOP 100 cable connector 140 racking device 141, 142 motion arm assembly 141b, 142b base 141t, 142t tubular gripper 141m, 142m arm segment 143 well center tool motion arm assembly 145 vertical rails 147 vertical axis bearing 147a bearing housing L left-hand attachment position R right-hand attachment position 148 connector for gripper or well center tool 149 roller 150 iron roughneck device 152, 153 hydraulic cylinder 154 hydraulic unit 156 connector pin 157 suspension beam 160 toothed rack 161 pinion 162 motor 170 electric power supply 171, 172 umbilical cable 179 fixed pulley 178 movable pulley 177 counterweight 200 controller 201 super capacitor