Drilling rig comprising tubular stand handling system

Abstract

The invention relates to a drilling rig comprising: a tubular stand support tower, tubular stand storage rack, slip device for supporting multiple tubular stands, and a tubular stand connecting device. According to the invention the rig is provided with a tubular stand handling system, adapted to move a tubular stand between the storage rack and a position in the firing line above the tubular string slip device, and adapted to rotatable support the tubular stand in the firing line during spinning in, to allow for connecting the tubular stand with the tubular string, and during spinning out, to allow for disconnecting the tubular stand from the tubular string, the tubular stand handling system comprising. The tubular stand handling system comprises vertical rails and a lower motion arm assembly and an upper motion arm assembly comprising grippers, mounted on said vertical rails. Also provided is a weight compensation control system.

Claims

1. A drilling rig, the drilling rig comprising: a tubular stand support tower, the tubular stand support tower defining a firing line; a tubular stand storage rack adapted for storage of tubular stands in vertical orientation therein, and wherein the tubular stand storage rack holds a plurality of tubular stands; a tubular string slip device, the slip device being adapted to support the weight of a tubular string suspended therefrom in the firing line; a tubular stand connecting device adapted to connect a lower pin end of one of the plurality of tubular stands to an upper box end of a tubular string supported in the firing line by the slip device, to extend the tubular string during tripping in, and/or to disconnect the lower pin end of the one of the plurality of tubular stands from the upper box end of the tubular string, to shorten the tubular string during tripping out; and a tubular stand handling system, adapted to move one of the plurality of tubular stands between the storage rack and a position in the firing line above the tubular string slip device, and adapted to rotatably support the one of the plurality of tubular stands in the firing line during spinning in, to allow for connecting the one of the plurality of tubular stands with the tubular string, and during spinning out, to allow for disconnecting the one of the plurality of tubular stands from the tubular string, the tubular stand handling system comprising: vertical rails, mounted to the tubular stand support tower along at east part of the firing line; and a lower motion arm assembly and an upper motion arm assembly, mounted on said vertical rails for respectively engaging one of the plurality of tubular stands at a lower region and an upper region thereof, wherein each motion arm assembly comprises: a mobile base, the mobile base being supported by the vertical rails, and being vertically mobile along said vertical rails by a vertical drive including a motor, the vertical drive being positioned on said mobile base; a motion arm being connected to said mobile base; and a tubular gripper member being connected to the motion arm, wherein the gripper member comprises: grippers for engaging a tubular section of one of the plurality of tubular stands, the grippers being movably supported for movement relative to the mobile base in a compensation direction directed parallel to the firing line, and the grippers being provided with rollers to enable the grippers to support the tubular section of the one of the plurality of tubular stands along a longitudinal axis of the one of the plurality of tubular stands while allowing rotation of the tubular section about the longitudinal axis; one or more compensator pistons, for moving the grippers relative to the mobile base in the compensation direction, wherein the one or more compensator pistons are configured to support the weight of the grippers and at least part of the weight of the one of the plurality of tubular stands engaged by the grippers; and a weight compensation control system, the control system controlling the compensator pistons of the lower motion arm assembly and the upper motion arm assembly, and the control system being adapted to increase the pressure in the compensator pistons when the one of the plurality of tubular stands is landed on the tubular string, by moving the lower motion arm assembly and the upper motion arm assembly and/or the grippers of the respective motion arm assemblies supporting the one of the plurality of tubular stands downward, to prevent the full weight of the one of the plurality of tubular stands from being transferred onto the tubular string.

2. The drilling rig according to claim 1, wherein the weight compensation control system is adapted to control the pressure in the compensator pistons, such that by an increase of the pressure the grippers are moved upward relative to the mobile base of the respective motion arm, to enable only part of the weight of the one of the plurality of tubular stands to be transferred onto the tubular string.

3. The drilling rig according to claim 1, wherein the grippers are supported by the compensator pistons, and the compensator pistons are configured to move the grippers along a weight support trajectory that extends parallel to the firing line and to a line of action of the compensator pistons.

4. The drilling rig according to claim 1, wherein the weight compensation control system is adapted to allow the one of the plurality of tubular stands to land on the tubular string by moving the motion arm assemblies in a downward direction along the vertical rails, and is adapted to actuate the compensator pistons when the one of the plurality of tubular stands contacts the tubular string such that not all of the weight of the one of the plurality of tubular stands is transferred onto the tubular string, and to keep the weight of the one of the plurality of tubular stands transferred onto the tubular string constant while the one of the plurality of tubular stands contacts the tubular string and the motion arm moves further downwards.

5. The drilling rig according to claim 4, wherein the weight compensation control system is adapted to stop the downward movement of the motion arm when the one of the plurality of tubular stands contacts the tubular string and the grippers are at a predetermined spinning height relative to the respective motion arm.

6. The drilling rig according to claim 1, wherein the weight compensation control system is adapted to position the pin end of the one of the plurality of tubular stands adjacent the box end of the tubular string, by lowering the motion arm, to land the one of the plurality of tubular stands on the tubular string by lowering the grippers relative to the motion arm, and to stop lowering the pressure in the compensator pistons when a predetermined tubular stand weight support pressure is reached to prevent the full weight of the one of the plurality of tubular stands to be transferred onto the tubular string.

7. The drilling rig according to claim 1, wherein the weight compensation control system is configured to reduce the pressure in the compensator pistons to lower the pin end of the one of the plurality of tubular stands into the box end of the tubular string during spinning in, and to increase the pressure in the compensator pistons to lift the pin end of the one of the plurality of tubular stands out of the box end of the tubular string during spinning out.

8. The drilling rig according to claim 1, wherein the weight compensation control system is configured to keep the pressure in the compensator pistons at a constant predetermined spinning in pressure during spinning in, and at a constant predetermined spinning out pressure during spinning out.

9. The drilling rig according to claim 1, wherein the weight compensation control system is linked to a spinner and/or a torque wrench for securing the one of the plurality of tubular stands to the tubular string, to receive torque data, and wherein the pressure in the compensator pistons is controlled based on the torque data.

10. The drilling rig according to claim 9, wherein the weight compensation control system controls the pressure in the compensator pistons based on spinning data received from the gripper member.

11. The drilling rig according to claim 1, wherein the tubular stand handling system further comprises a tubular stand rotation device for rotating the one of the plurality of tubular stands in order to facilitate connection of the one of the plurality of tubular stands to the tubular string.

12. A method for landing the one of the plurality of tubular stands on a tubular string using the drilling rig according to claim 1, the method comprising the steps of: engaging the one of the plurality of tubular stands with the grippers of the motion arm assemblies; actuating the compensator pistons to provide a predetermined tubular stand weight support pressure; lifting the one of the plurality of tubular stands, moving the one of the plurality of tubular stands into the firing line, and positioning the one of the plurality of tubular stands above the tubular string supported in the slip device, using the motion arm assemblies; landing the one of the plurality of tubular stands on the tubular string by lowering the motion arm assemblies and/or the grippers in a downward direction; keeping the predetermined tubular stand weight support pressure constant when the one of the plurality of tubular stands contacts the tubular string to thus transfer only part of the weight of the one of the plurality of tubular stands onto the tubular string while supporting the rest of the weight with the motion arm assemblies.

13. The method according to claim 12, further comprising the steps of: connecting the one of the plurality of tubular stands to the tubular string; spinning the one of the plurality of tubular stands while using the compensator pistons to lower the pin end of the one of the plurality of tubular stands into the box end of the tubular string, keeping the tubular stand weight support pressure constant while lowering the one of the plurality of tubular stands; after the one of the plurality of tubular stands has been secured to the tubular string, reducing the pressure in the compensator pistons to transfer the full weight of the one of the plurality of tubular stands on the tubular string; and releasing the one of the plurality of tubular stands with the grippers of the motion arm assemblies.

14. The method according to claim 12, further comprising the step of: during landing on, and connecting to, the tubular string, keeping the percentages of weight of the one of the plurality of tubular stands transferred to the tubular string below 30%.

15. The method according to claim 12, further comprising the step of: using the compensator pistons to land the one of the plurality of tubular stands on the tubular string, while only part of the weight of the one of the plurality of tubular stands is transferred to the tubular string.

16. The method according to claim 15, further comprising the steps of: prior to landing the one of the plurality of tubular stands on the tubular string: actuating the compensator pistons by increasing the pressure in the compensator pistons until the pressure in the compensator pistons remains constant; further increasing pressure in the compensator pistons, moving the grippers and the one of the plurality of tubular stands supported by the grippers upwards relative to the respective motion arms; when the grippers have at least obtained a predetermined spinning height relative to the respective motion arm, lowering the motion arm assemblies in the downward direction to position the pin end of the one of the plurality of tubular stands adjacent to, but spaced from, the box end of the tubular string; and landing the one of the plurality of tubular stands on the tubular string using the compensator pistons.

17. The method according to claim 12, the method further comprising the step of: using the motion arm assemblies to land the one of the plurality of tubular stands on the tubular string, while only part of the weight of the one of the plurality of tubular stands is transferred to the tubular string.

18. The method according to claim 17, further comprising the steps of: prior to landing the one of the plurality of tubular stands on the tubular string: actuating the compensator pistons by increasing the pressure in the compensator pistons to provide the predetermined tubular stand weight support pressure, the tubular stand weight support pressure being less than 100% of the tubular stand weight; and lowering the motion arm assemblies in the downward direction to land the one of the plurality of tubular stands on the tubular string.

19. The method according to claim 18, further comprising the steps of: after the one of the plurality of tubular stands has landed on the tubular string, further lowering the motion arm assemblies while keeping the tubular stand weight support pressure constant, and thus keeping the weight transferred onto the tubular string constant, thus moving the grippers upwards relative to the respective motion arm; and when the grippers have obtained a predetermined spinning height relative to the respective motion arm, stopping the movement of the motion arm assemblies in the downward direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 shows a perspective view of an exemplary embodiment of a drilling rig according to the invention;

(3) FIG. 2 shows a side view of an exemplary embodiment of a gripper member according to the invention;

(4) FIG. 3 shows a perspective view of the gripper of FIG. 2;

(5) FIG. 4 shows a side view of the gripper of FIG. 2 engaging a tubular stand;

(6) FIG. 5 shows in cross section a compensator piston of the gripper member of FIG. 2 in a retracted position;

(7) FIG. 6 shows in cross section the compensator piston of FIG. 5 in an extended position;

(8) FIG. 7 shows in cross section the gripper member of FIG. 2;

(9) FIG. 8 shows a top view of the gripper member of FIG. 2 with grippers engaging a tubular with a first diameter and engaging a tubular with a second diameter

(10) FIG. 9 shows a top view of the gripper member of FIG. 2 with closed grippers and with opened grippers;

(11) FIG. 10 shows a perspective view of an exemplary embodiment of a motion arm assembly according to the invention;

(12) FIG. 11 shows a top view of the motion arm assembly of FIG. 10;

(13) FIG. 12 shows a perspective view of a motion arm of the motion arm assembly of FIG. 10;

(14) FIG. 13 shows a side view of the motion arm assembly of FIG. 10; and

(15) FIG. 14 shows a partial side view of an exemplary embodiment of a drilling rig according to the invention.

DETAILED DESCRIPTION

(16) FIG. 1 shows a perspective view of an exemplary embodiment of a drilling rig 01 according to the invention.

(17) The drilling rig 1 comprises a tubular stand support tower in the form of a multipurpose tower 2, a tubular stand storage rack 3 supporting tubular stand 4 on each side of the multipurpose tower, a tubular string slip device 5 supporting a tubular string 6, a tubular stand connection device 7 and a tubular stand handling system 8.

(18) In the embodiment shown, the tubular stand support tower is embodied as a multipurpose tower, configured to handle different types of tubulars, e.g. drilling tubulars and casing tubulars, and to compose insert a string of tubular stands into a well bore and remove a string of tubular stand from a well bore. The multipurpose tower is furthermore adapted to assist in drilling a wellbore, e.g. by supporting and driving a drilling string.

(19) The multipurpose tower defines a firing line 12 alongside a frontal surface. The firing line is concentric with the slip device 5 supporting the tubular string 6. The tubulars string slip device 5 is adapted to support the weight of a tubular string comprising multiple tubular stands.

(20) The multipurpose tower 2 is on opposite sides provided with the tubulars stand storage racks 4, in the embodiment shown in the form of carousels, adapted for storage of tubular stands 3, e.g. sets of combined drilling tubulars, in vertical orientation therein.

(21) The tubular stand connecting device 7, is adapted to connect a lower pin end 9 of the tubular stand 3 to an upper box end 10 of the tubular string 6 supported in the firing line 12 by the slip device 5. The tubular stand connection device is adapted to extend the tubular string, during tripping in, and/or to disconnect the lower pin end of the tubular stand from the upper box end of the tubular string, to shorten the tubular string during tripping out. The tubular stand connection device 7 can be a power tong and/or a spinner and/or a torque wrench or a combination of two or more of these.

(22) The tubular stand handling system 8 is adapted to move a tubular stand 3 between the storage rack 4 and a position in the firing line 12 above the tubular string slip device 5. The tubular stand handling system 8 is furthermore adapted to rotatable support the tubular stand 3 in the firing line 12 during spinning in, to allow for connecting the tubular stand 3 with the tubular string 6, and during spinning out, to allow for disconnecting the tubular stand 3 from the tubular string 6.

(23) The tubular stand handling system 8 comprises vertical rails 13, a lower motion arm assembly 14, an upper motion arm assembly 15, and a weight compensation control system 16.

(24) In the particular embodiment shown, the multi purpose tower 2 is provided with two vertical rails 13, each mounted to the multi purpose tower along at least part of the firing line. The rails are each provided with motion arm assemblies.

(25) In the embodiment shown, the right vertical rails 13 is provided with the lower motion arm assembly 14 and the upper motion arm assembly 15 of the tubular stand handling system, to move tubulars from the tubular stand storage rack located on the right side of the multipurpose tower into the firing line.

(26) The lower motion arm assembly 14 and an upper motion arm assembly 15 are moveably mounted on the vertical rails for respectively engaging a tubular stand at a lower region and at an upper region thereof.

(27) In the preferred embodiment shown, the tubular stand handling system 8 is furthermore provided with a third motion arm assembly 25, supported on the vertical rails 13 above the lower motion arm assembly 14 and below the upper motion arm assembly 15, for engaging a tubular stand at a mid-section thereof.

(28) The left vertical rails 13′ is provided with a motion arm assembly 14′ that supports a tubular stand connection device in the form of a torque wrench combined with a spinner 7 (not shown in detail). It is submitted that the motion arm assembly supporting the tubular stand connection device is shown in a raised position. When the connection device is active, i.e. is connecting or disconnecting a tubular stand, it is supported by the motion arm assembly in a position closer to the slip device, more in particular at the top end of the tubular string supported in the slip device.

(29) The motion arm assemblies are partially shown in detail in FIGS. 10-13. Each motion arm assembly comprises a mobile base 17, a motion arm 18, and a tubular gripper member 19. The latter is shown in detail in FIGS. 2 and 3.

(30) The mobile base 17 of a motion arm assembly is supported by the vertical rails 13, and is vertically mobile along said vertical rails by a vertical drive including a motor, which vertical drive is positioned on said mobile base.

(31) The motion arm 18, shown in isolation in FIG. 12, is connected to the mobile base 17. In the embodiment shown, the motion arm 18 is pivotably connected to the mobile base 17 for pivoting about a vertical axis. Thus, the motion arm assemblies are configured to move a tubular stand into and out of the firing line by pivoting the motion arm about the vertical axis. In the embodiment shown, the motion arms furthermore are telescopic arms. The motion arm 18 is shown in an extended configuration in FIG. 12 and in a retracted position in FIGS. 10, 11 and 13.

(32) In the embodiment shown, the mobile arm assemblies on the rails 13, on the right side of the tower, are provided with gripper members according to the invention. The tubular gripper members 19 are connected to the motion arm 18 of the mobile arm assemblies.

(33) In the embodiment shown, the motion arm assemblies are configured to move independently from each other and are adapted to support different tools. Thus, the gripper members can be replaced with different tool when needed.

(34) According to the invention, the gripper members 19 comprise grippers 20, shown in detail in FIGS. 2, 3 and 7-9, and one or more compensator pistons 21, shown in detail in FIGS. 5 and 6.

(35) The grippers 20 are configured for engaging a tubular section 11 of a tubular stand 3, and are provided with rollers 22 to enable the gripper to support a tubular section of a tubular stand 3 along a longitudinal axis 23 of that tubular stand while allowing rotation of that tubular section about that longitudinal axis.

(36) According to the invention, the grippers 20 are movably supported for movement relative to the mobile base 17 in a compensation direction directed substantially parallel to the firing line 12.

(37) The gripper members 19 further comprises one or more compensator pistons 24 for moving the grippers 20 relative to the mobile base 17, and preferably relative to the motion arm 18, in the compensation direction. The one or more compensator pistons 24 are configured to support the weight of the grippers and at least part of the weight of the tubular stand engaged by the grippers.

(38) In the preferred embodiment shown, see for example FIGS. 5 and 6, the grippers 20 are supported by the compensator pistons 21, more in particular are hingeably connected to a lower end of the vertically orientated compensator piston. Thus, the grippers are moved by the compensator pistons along a weight support trajectory that extends parallel to the firing line and to a line of action of the piston, i.e. the central axis of the piston.

(39) According to the invention, the tubular stand handling system 8 comprises the weight compensation control system 16, which control system controls the compensator pistons 24 of the motion arm assemblies, and which control system is adapted to increase the pressure in the compensator pistons when the tubular stand is landed on the tubular string, by moving the motion arm assembly and/or the grippers supporting the tubular stand downward, to prevent the full weight of the tubular stand from being transferred onto the tubular string.

(40) Thus, the tubular stand handling system can be used to land the tubular stand on the tubular string by moving the motion arm assemblies and/or by moving the grippers in a downward direction along the firing line. In a preferred embodiment, the tubular stand is landed on the tubular string by lowering the motion arm assembly, and the tubular stand is moved downward while being connected to the tubular string by lowering the grippers relative to the motion base of the motion arm assemblies, using the compensator pistons.

(41) According to the invention, during landing of the tubular stand on the tubular string, during connecting the tubular stand to the tubular string, and during disconnecting the tubular stand form the tubular string, the weight compensation control system, more in particular the compensator pistons of the weight compensation control system, can be used to compensate part of the weight of the tubular stand, and thus prevent the full weight of the tubular stand to bear down on the tubular string while the tubular stand is not fully connected to the tubular string.

(42) Thus, the multipurpose tower shown in the figures, more in particular the tubular stand handling system of the multipurpose tower, can be used for landing a tubular stand on a tubular string using a method according to the invention, the method comprising the steps:

(43) engaging the tubular stand 3 with the grippers 20 of the motion arm assemblies 14,15,25;

(44) actuate the compensator pistons 21 to provide predetermined stand weight support pressure;

(45) lift the tubular stand 3, move tubular stand 3 into the firing line 12, and position the tubular stand 3 above the tubular string 6 supported in the slip device 5, using the motion arm assemblies 14,15,25;

(46) land the tubular stand 3 on the tubular string 6 by lowering the motion arm assemblies 14,15,25 and/or the grippers 20 in a downward direction;

(47) keep the predetermined stand weight support pressure substantially constant when the tubular stand 3 contacts the tubular string 6 to thus transfer only part of the weight of the tubular stand 3 onto the tubular string 6 while supporting the rest of the weight with the motion arm assemblies 14,15,25.

(48) Furthermore, the multipurpose tower shown in the figures, more in particular the tubular stand handling system of the multipurpose tower, can be used for connecting the tubular stand to the tubular string, the method comprising the steps:

(49) spinning the tubular stand 3 while using the compensator pistons 21 to lower the pin end 9 of the tubular stand 3 into the box end 10 of the tubular string 6, keeping the stand weight support pressure substantially constant while lowering the tubular stand 3;
after the tubular stand 3 has been secured to the tubular string 6, reduce the pressure in the compensator pistons 21 to transfer the full weight of the tubular stand 3 on the tubular string 6;
release the tubular stand 3 with the grippers 20 of the motion arm assemblies 14, 15, 25.

(50) In a further preferred method according to the invention, the motion arm assemblies are used to land the tubular stand on the tubular string, while only part of the weight of the tubular stand is transferred to the tubular string. Such a method comprises the steps: prior to landing the tubular stand on the tubular string:
actuate the compensator pistons by increasing the pressure in the compensator pistons to provide predetermined stand weight support pressure, which stand weight support pressure is less than 100% of the tubular stand weight, e.g. 90% of the stand weight;
lower the motion arm assembly in the downward direction to land the tubular stand on the tubular string;
and preferably, after the tubular stand has landed on the tubular string, further lower the motion arm assemblies while keeping the stand weight support pressure substantially constant, and thus keep the weight transferred onto the tubular string substantially constant, thus moving the grippers upwards relative to the motion arm; and
when the grippers have obtained a predetermined spinning height relative to the motion arm, stop the movement of the motion arm assembly in the downward direction.

(51) FIG. 14 shows a partial side view of an exemplary embodiment of a drilling rig according to the invention, more in particular shows parts of a tubular stand support tower in the form of a drilling tower 102, a tubular string slip device 105 supporting a tubular string 106, a tubular stand connection device 107 and a tubular stand handling system 108.

(52) The drilling tower 102 defines a firing line alongside a frontal surface of the drilling tower. The firing line is concentric with the slip device 105 supporting the tubular string 106. The tubulars string slip device 105 is adapted to support the weight of a tubular string comprising multiple tubular stands.

(53) The tubular stand handling system 108 comprises a vertical rails 113, mounted to the drilling tower 102 along at least part of the firing line, a lower motion arm assembly 114 and an upper motion arm assembly 115, mounted on the vertical rails 113.

(54) In the embodiment shown, the tubular stand handling system 108 is adapted to support the tubular stand 103 in a lower region and in an upper region thereof. The lower motion arm assembly 114 and the upper motion arm assembly 115 engage a tubular stand 103 at a lower region and an upper region of the tubular stand. This is in particular beneficial when manipulating long, and thus comparatively flexible, tubular stands.

(55) In a further embodiment, an additional motion arm assemblies, also controlled by the weight compensation control system, to provide additional support and/or allow for handling extra-long pipe stand. For example, the tubular stand handling system may comprise a third, intermediate motion arm assembly, located above the lower motion arm assembly and below the upper motion arm assembly on the vertical rail, to support the tubular stand at a mid-section.

(56) In the embodiment shown, an additional motion arm assembly 126 is provided to support the tubular stand connection device 107. The third motion arm assembly 126 is located below the lower motion arm assembly 114 and the upper motion arm assembly 115 on the vertical rails 113.

(57) The tubular stand connecting device 107, is adapted to connect and to disconnect a lower pin end 109 of the tubular stand 103 supported by the tubular stand handling system respectively to and from an upper box end 110 of the tubular string 106 supported in the firing line 112 by the slip device 105.

(58) Both the lower motion arm assembly 114 and the upper motion arm assembly 115 comprise a motion arm 118 and a tubular gripper member 119. The gripper member 119 is connected to the motion arm 118 of the mobile arm assemblies 114,115.

(59) In the embodiment shown, the motion arm assemblies are configured to move independently from each other and are adapted to support different tools. The gripper members can be replaced with a different tool when needed. According to the invention, the gripper members 119 comprise grippers 120 and a compensator piston 121.

(60) The grippers 120 are provided with rollers 122 to enable the gripper to support the tubular stand 103 while allowing rotation of that tubular stand about its longitudinal axis.

(61) The grippers 120 are movably supported by the compensator piston 121 for movement relative to the respective motion arm assemblies 114,115 in a compensation direction directed substantially parallel to the firing line 12.

(62) The one or more compensator pistons 124 are configured to support the weight of the grippers and at least part of the weight of the tubular stand engaged by the grippers.

(63) A weight compensation control system 116 controls the compensator pistons 121 of the lower motion arm assembly 114 and the upper motion arm assembly 115.

(64) The weight compensation control system is adapted to increase the pressure in the compensator pistons when the tubular stand is landed on the tubular string, by moving the motion arm assembly and/or the grippers supporting the tubular stand downward, to prevent the full weight of the tubular stand from being transferred onto the tubular string.

(65) Thus, during landing of the tubular stand on the tubular string, during connecting the tubular stand to the tubular string, and during disconnecting the tubular stand form the tubular string, the weight compensation control system, more in particular the compensator pistons of the weight compensation control system, can be used to compensate part of the weight of the tubular stand, and thus prevent the full weight of the tubular stand to bear down on the tubular string while the tubular stand is not fully connected to the tubular string.

(66) The weight compensation control system comprises a hydraulic power system for actuating the compensator pistons. The lower motion arm assembly and the upper motion arm assembly are each provided with a hydraulic power system, which are linked to the weight compensation control system. Linking them to the weight compensation control system allows for the motion arm assemblies to operate in unison. i.e. to enable synchronous movement of the grippers and control of even load sharing over the assemblies.

(67) In the embodiment shown, the weight compensation control system 116 is also linked with the tubular stand connecting device 107 to use the tubular stand connecting device in conjunction with the pipe handling system.

(68) In the embodiment shown, the tubular stand connecting device is torque wrench with a spinner, supported by the third motion arm assembly 126, for securing the tubular stand to the tubular string.

(69) The weight compensation control system is linked to the spinner and the torque wrench to receive torque data. Thus, the pressure in the compensator pistons can be controlled based on the torque data. Also, the weight compensation control system can control the pressure in the compensator pistons based on spinning data received from the gripper member, e.g. the position of the grippers relative to the mobile base, the rotation of the stand about its tubular axis, etc.

(70) In the embodiment shown, the tubular stand connecting device is torque wrench with a spinner. In addition, or as an alternative, the tubular stand handling system may further comprise a tubular stand rotation device for rotating the tubular in order to facilitate connection of the tubular stand to the tubular string.

(71) In the embodiment shown, the weight compensation control system 116 is furthermore provided with sensors (not shown) for providing operational information of the compensator pistons, e.g. pressure information and/or position information or load information and with sensors that provide information on the load supported by the grippers.

(72) The weight compensation control system 116 can be used to adjust the percentage of the stand weight transferred onto the tubular string during the spinning process. For example, if at the beginning of the spinning process the torque required for rotating the tubular stand is relatively high, the amount of transferred stand weight may be reduced in order to lower friction, and thus reduce the required torque, which may prevent damage to the threads.

(73) The tubular stand handling system 108 can land the tubular stand 103 on the tubular string 106 by lowering the upper motion arm assembly 115 and the lower motion arm assembly 114, i.e. moving the motion arm assemblies in a downward direction along the rails, and, subsequently, while the tubular stand 103 is being connected to the tubular string 106, move the tubular stand further downward by lowering the grippers 120 relative to the respective motion arm assemblies, using the compensator pistons 121.

(74) Also, the multipurpose tower shown in FIG. 14, more in particular the tubular stand handling system of the multipurpose tower, can be used for landing a tubular stand on a tubular string using a method according to the invention, the method comprising the steps:

(75) engaging the tubular stand 103 with the grippers 120 of the respective motion arm assemblies 114,115;

(76) actuate the respective compensator pistons 121, to provide predetermined stand weight support pressure;

(77) lift the tubular stand 103, move tubular stand 103 into the firing line 112, and position the tubular stand 103 above the tubular string 106 supported in the slip device 105, using the motion arm assemblies 114,115;

(78) land the tubular stand 103 on the tubular string 106 by lowering the motion arm assemblies 114,115 relative to the drilling tower and/or by lowering the grippers 120 relative to the motion arm assemblies;

(79) keep the predetermined stand weight support pressure substantially constant when the tubular stand 103 contacts the tubular string 106 to thus transfer only part of the weight of the tubular stand 103 onto the tubular string 106 while supporting the rest of the weight with the motion arm assemblies 114,115.

REFERENCE SIGNS

(80) 01 drilling rig 02 tubular support tower 03 tubular stand 04 tubular stand storage rack 05 tubular string slip device 06 tubular string 07 tubular stand connection device 08 tubular stand handling system 09 pin end tubular 10 box end tubular 11 tubular section tubular 12 firing line 13 vertical rails 14 lower motion arm assembly 13 upper motion arm assembly 16 weight compensation control system 17 mobile base 18 motion arm 19 gripper member 20 grippers 21 compensator piston 22 rollers 23 longitudinal axis tubular stand 25 intermediate motion arm assembly 102 tubular support tower 103 tubular stand 105 tubular string slip device 106 tubular string 107 tubular stand connection device 108 tubular stand handling system 109 pin end tubular 110 box end tubular 111 tubular section tubular 112 firing line 113 vertical rails 114 lower motion arm assembly 115 upper motion arm assembly 116 weight compensation control system 117 mobile base 118 motion arm 119 gripper member 120 grippers 121 compensator pistons. 122 rollers 123 longitudinal axis tubular stand 125 intermediate motion arm assembly 126 third motion arm assembly