NL2009935C2

NL2009935C2 - Radial clamping/sealing system and drilling system provided therewith for (semi)-continuous drilling a borehole, drilling rig comprising such system, and method there for.

Info

Publication number: NL2009935C2
Application number: NL2009935A
Authority: NL
Inventors: Alexander Michaël Noordstrand
Original assignee: A M N Dev B V
Priority date: 2012-12-05
Filing date: 2012-12-05
Publication date: 2014-06-10
Also published as: WO2014088417A1; US20150300103A1; EP2929127A1; AU2013356776A1; CN104995370B; CA2893865A1; AU2013356776B2; CN104995370A

Abstract

Invention relates to a system and associated method for continuous and/or semi-continuous drilling a borehole, comprising:—a first stationary housing;—a rotatable housing comprising a longitudinal opening for receiving a drill string; and—a radial clamping system configured for holding and clamping the box end of the drill string in substantially radial direction with respect to the rotatable housing;—a first direct sealing system in use arranged between drill pipe and the rotatable housing;—a second indirect sealing system in use arranged between the rotatable housing and the stationary housing;—a mechanical and/or hydraulic transmission configured for radial activation of the radial clamping system; and—a first drive configured for rotating the rotatable housing with the drill string.

Description

Radial clamping/sealing system and drilling system provided therewith for (semi)-continuous drilling a borehole, drilling rig comprising such system, and method there for 5 The present invention relates to a radial clamping/sealing system for a drilling system for (semi)-continuous drilling a borehole. Such drilling system is used in exploration and production drilling relating to oil and gas production at sea or on land.

10 Conventional drilling systems are based on a

Kelly-drive rotary approach. This approach is well-established in practice. In this approach the top of the drilling rig is connected to a swivel that is hung in a travelling block. This travelling block is suspended by 15 steel cables to the crown block at the top of a so-called derrick. The hoisting system is used to raise and lower the drill string and to vary the weight on the drill bit during drilling. Drilling fluid enters the swivel through a gooseneck. A bearing in the lower part of the swivel allows 20 the Kelly and the drill string to rotate, while the other part of the swivel remains stationary. A so-called Kelly section is provided between the top of the drill string and the swivel. The outer surface of the Kelly is used to exert torque on the drill string and can be of various shape 25 including square and hexagonal shapes. The Kelly section is capable of moving vertically through a matching bushing with the bushing transmitting rotary power to the Kelly. This bushing is locked into a rotary table that is hydraulically or electrically powered. When a new drill pipe or drill pipe 30 section is needed the Kelly needs to be disconnected from the drill string and has to be connected to the new section after which this new pipe section is connected to the drill string. Therefore, the Kelly, which is connected by a 2 threaded connection to the top of the drill string, executes all the required functions for the drilling operation. This disconnecting and reconnecting requires additional labor in the field and results in a standstill of the operation.

5 Another conventional system uses a top drive rotary drilling approach. In this approach a top drive is connected with a threaded connection/quill to the top of the drill string. The top drive is used to rotate, apply torque and hoist the drill string. In addition, drilling fluid can 10 be injected into the drill string. In case a new pipe section is needed the top drive needs to be disconnected, and as a next step, to be connected to the new pipe section. After connecting the new pipe section to the drill string, the drilling operation can continue.

15 Besides problems associated with the requirement of additional labor in the field and standstill of the operation during connection of a new pipe section, other problems may occur during such standstill. For example, a drill string can get stuck in the borehole due to the 20 standstill. Also, the interruption of the drilling fluid during connection of a new pipe section limits control of the down hole pressure and dropping cuttings. These problems restrict the areas and types of formation that can be explored for oil and gas, for example.

25 The present invention has for its object to obviate or at least reduce the above stated problems.

The present invention provides a radial clamping/sealing system for a drilling system for (semi)-continuous drilling a borehole according to the invention, 30 the drilling system comprising: a stationary housing; a rotatable housing comprising first clamping means for clamping and holding a drill string with a 3 drill bit in a substantially radial direction of the drill string; and a first drive for rotating the rotatable housing with the drill string, 5 wherein the rotatable housing comprises a first direct seal between the clamping means and the drill string, and a second indirect seal between the rotatable housing and the stationary housing.

When drilling a borehole with a system according 10 to the present invention a number of functions needs to be fulfilled. The drill string/drill pipe has to be hoisted, rotated and torque has to be applied to the drill string. Furthermore, drilling fluid has to be injected during the drilling or tripping.

15 By having at least the first clamping means clamping and holding the drill string in a substantially radial direction of the drill string such that the upper end of the drill string is approachable for other equipment, including the positioning of an additional pipe section, a 20 continuous or semi-continuous/near continuous operation is achieved. By clamping the drill string directly instead of its upper end a standstill for connection of an additional drill pipe section is not required. Conventional systems require an axial (threaded) connection for hoisting the 25 drill string, such that a standstill is required having the aforementioned problems that are obviated or at least reduced by the present invention.

The stationary housing together with the rotatable housing are capable of hoisting the drill string with a 30 drill bit such that the entire weight of the drill string is supported. The drill string is rotated by one or two or even more drives of which at least one drive associated with the rotatable housing is a rotational drive acting from a 4 rotational direction onto the drill string. The support of the drill string can be achieved by the clamping means. In a presently preferred embodiment the clamping means comprise clamping parts and support parts that cooperate with each 5 other.

According to the present invention the rotatable housing comprises a first direct seal between the clamping means and the drill string, and a second indirect seal between the rotatable housing and the stationary housing.

10 The sealing function is performed by an indirect sealing between the rotatable housing and a stationary housing. A first direct sealing seals the rotatable housing against the jointly rotating drill string or pipe section. This enables an optimal design of the sealing function 15 without the constraints of the drill string or pipe section. For example, the surface areas of the drill string and housing can be designed for optimal sealing such that also relatively rough surfaces of the drill string can be sealed.

According to a presently preferred embodiment of 20 the invention, the drill string preferably is supported at the elevator shoulder. This elevator shoulder is an angled section of the drill string that can be supported by the clamping means.

The invention also relates to a drilling system 25 for (semi)-continuous drilling a borehole comprising a radial clamping/sealing system as described above as first clamping means, and further comprising: second clamping means for clamping the drill pipe; 30 - a second drive for rotating the drill string cooperating with the second clamping means; 5 guiding means for enabling a substantially axial movement of at least one of first and second drives; and control means controlling the first and second 5 drive such that in operation the drill string is substantially continuously driven by the first and/or second drives.

Providing two separate drives enables the rotation of the drill string with one drive while the other drive is 10 connected to another pipe section. This preferably enables a continuous drilling system, or at least a semi-continuous or near continuous drilling system, for drilling a borehole. Providing two separate drives omits undesired standstill of the drilling operation for connecting a new pipe section.

15 More specifically, the system according to the invention is capable of performing the required functions also during connection and disconnection. This enables a faster drilling process and allows for continuous circulation of drilling fluid leading to an improved control of down hole pressure, 20 so that more difficult formations of subterranean structures can be drilled, and cuttings are not dropping to the bottom of the borehole.

In case the first drive comprises the first clamping means and the second drive comprises a conventional 25 drive system, such as a so-called top drive, the first drive rotates the drill string. The rotatable housing directly engages the drill string and rotates at the same rotational speed. When the upper end of the drill string with the rotatable housing reaches a working platform, or other 30 structural part of the rig, the top drive positions connects a new pipe section with second clamping means. In case of a top drive this involves a threaded connection. The second drive may rotate the drill string for a period of time after 6 the additional pipe section is connected to the drill string. The first drive and the rotatable housing are repositioned. After the first clamping means start clamping the drill string the first drive again takes over the 5 function of rotating the drill string from the second drive. The second drive is then available for providing a further additional pipe section. This enables a continuous or semi-continuous drilling operation.

In an alternative embodiment, in case both the 10 first and second drives involve a rotatable housing the drilling system may apply a so-called "hand-over-hand" approach. The first drive rotates the drill string. When the upper end of the drill string with the first rotatable housing associated with the first drive reaches the working 15 platform, or other structural part of the rig, the second drive associated with a second rotatable housing comprising second clamping means positions an additional pipe section. After the additional pipe section is connected to the drill string the second drive may rotate the drill string. The 20 first drive is then available for providing a further additional pipe section and to position this pipe section to the drill string. This further pipe section is connected to the drill string, preferably before the upper end of the drill string with the second rotatable housing of the second 25 drive reaches the working platform or other structural part of the rig. This enables a continuous or semi-continuous drilling operation. This is achieved by performing the sealing, supporting and rotating functions by the rotatable housing in a substantially radial direction relative to the 30 drill string. In a presently preferred embodiment of the invention the clamping means comprises parts or sections that can be separated from each other to enable 7 repositioning of the clamping means relative to the drill string or pipe section.

Preferably, a fluid supply system is used in the drilling system according to the present invention for 5 continuously supplying drilling fluid. This fluid serves as cooling means for the drill bit and for removing material from the borehole. Such fluid supply systems are known in practice. For example, a so-called continuous circulation system (CCS) is commercially available and has been applied 10 to a couple of rigs. In combination with one of the embodiments of the drilling system according to the invention this fluid supply system enables circulating drilling fluid during the connection of a new pipe section or removing a pipe section from the drill string during 15 drilling or tripping without a standstill of the operation. Alternative sub-optimal solutions for fluid supply are no longer needed.

Preferably, the guiding means are configured such that at least one of the first or second clamping means are 20 capable of positioning an additional pipe section on the drill string by performing the clamping in a direction with a substantial radial component. Even more preferably, both the first and second clamping means are capable of positioning the additional pipe section on the drill string. 25 In this latter case a so-called "hand-over-hand" system for holding and driving the drill string can be achieved. In such system, both the first and second drives act from a radial direction onto the drill string and perform the relevant functions of sealing, supporting and rotating in a 30 substantial radial direction relative to the drill string. The first and second drives can be changed in position with the second drive for placing a new pipe section on the drill string. Preferably, in such embodiment both the first and 8 second clamping means are associated with a separate rotatable housing such that the first and second drives can preferably be separated.

In an advantageous preferred embodiment according 5 to the present invention, the first clamping means comprise a number of clamping parts that move relative to each other in at least a radial direction for clamping and unclamping the drill string or pipe section.

By providing the clamping means from a number of 10 separable clamping parts, for example two or four clamping parts, the clamping means can be separated to release the drill string or pipe section. This enables an easy positioning of the clamping means around the drill string or pipe section.

15 Furthermore, by providing the clamping means with clamping parts, the clamping and sealing functions can be separated. The clamping parts directly clamp the drill string or pipe section. The clamping parts rotate together with the drill string during a drilling operation. This 20 enables an optimal design of the clamping parts.

In a presently preferred embodiment the clamping mechanism is activated automatically from the interaction between the clamping parts and the elevator shoulder. This obviates the need for a separate control system to active 25 clamping force.

In a presently preferred embodiment, the first direct and/or second indirect seals comprise seal parts. The use of seal parts enables an integrated design of the clamping parts and the seal parts.

30 In a further preferred embodiment the first and and/or second seals comprise a number of sub-seals. By providing sub-seals it is possible to deal with the relatively high pressures in a rather gradual way. A number 9 of sub-seals, placed in series, jointly provides the sealing function. This reduces the constraints on an individual subseal .

In a further advantageous preferred embodiment 5 according to the present invention, the drilling system further comprises a lever for increasing the clamping force of the clamping means on the drill string.

By providing a lever the clamping force acting on the drill string or pipe section can be controlled. In a 10 presently preferred embodiment the lever is provided with a lever arm to increase the force acting on the drill string or pipe section. In a further presently preferred embodiment the lever operates with the clamping parts described earlier that preferably to engage the angled section of the drill 15 string. This enables a close contact between the clamping parts and the drill string with an increased clamping force acting on the drill string.

Preferably, the system further comprises a self-supporting structure comprising the lever such that a load 20 acting downward in an axial direction of the drill string increases the clamping force. By providing the lever such that clamping forces increase in presence of an axial operating load the structure contributes to the overall safety of the system.

25 In a presently preferred embodiment the clamping force is activated by a support pad with the clamping force being such that torque can be transferred to the drill string, and preferably the sealing is also activated automatically. Alternatively, or in combination, an external 30 system is used to provide additional clamping force.

In a further advantageous preferred embodiment according to the present invention, the first and/or second clamping means of the drilling system comprise inserts 10 enabling the handling of different drill string diameters/dimensions.

The use of inserts enables application of the drilling system according to the invention over a range of 5 pipe dimensions by switching and/or removing/adding inserts. The range of pipe dimensions may involve different pipe diameters, different elevator shoulder angles, etc.

Providing inserts increases the flexibility of the system to handle different pipe diameters/dimensions without requiring 10 structural changes to the system. Preferably the use of inserts is combined with releasable and/or replaceable inner or first seals to enable coping with different piping diameters .

The present invention further relates to a 15 drilling rig comprising a drilling system as described above .

Such drilling rig provides the same effects and advantages as described for the drilling system.

The present invention further also relates to a 20 method for (semi)-continuous drilling a borehole, the method comprising: - providing a clamping/sealing system and/or a drilling system and/or a drilling rig as described above; 25 - clamping the drill string with the first clamping means; - rotating the drill string with the first drive; and - clamping an additional pipe section with the 30 second clamping means and connecting the pipe section to the drill string.

Such a method provides the same effects and 11 advantages as described for the drilling system and/or drilling rig. The method according to the invention preferably enables a continuous or semi-continuous or near continuous operation of the drilling. This is achieved by 5 performing the different functions that are described earlier, to a large extent in a substantially radial direction. This may involve the use of a rotational drive, clamping the drill string and/or the pipe sections in a substantially radial direction and providing an indirect 10 seal that is positioned at a radial distance from the drill string.

When drilling a borehole periodically additional pipe sections are required. In case the drill string is rotated with the first drive a second drive with second 15 rotatable housing and second clamping means connect a pipe section to the drill string. By starting to rotate the drill string with the second drive the first drive with first clamping means can be released from the drill string to enable connecting an additional pipe section in a "hand-20 over-hand" system. Alternatively, a conventional top drive is used as second drive comprising the second clamping means. After an additional pipe section is connected to the drill string the first drive and first rotatable housing are repositioned to take over from the second drive. The second 25 drive is ready to get another pipe section.

In a presently preferred embodiment the clamping of the drill string comprises moving a lever preferably comprising a lever arm, to increase the clamping force of the clamping means on the drill string or pipe section.

30 Preferably, this involves the clamping parts that are described before. The provision of clamping parts may involve the use of seal parts.

12

Further advantages, features and details of the invention will be elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which: 5 - fig. 1 A-B show a schematic representation of a drilling rig with a drilling system according to the invention; - fig. 2 A-C show a schematic representation of stationary and rotatable housings that contact 10 the drill string; fig. 3 A-B show the clamping function in a clamped and unclamped state; fig. 4 A-D show parts of the housing; and fig. 5 shows a side view of the rotatable 15 housing.

Drilling rig 2 (Fig. 1 A) comprises a drilling system 4 with working platform/floor 6. A drill string 8 is with one end positioned in borehole 12 and with the other end connected to drill bit 14. Pipe section 10 is to be 20 connected with drill string 8 to enable advancing pipe 8 into borehole 12. In the illustrated embodiment first drive 16, which in the illustrated state makes contact with the top of drill string 8, is associated with first stationary and rotatable housing configuration 18. Configuration 18 25 comprises with first clamping means 20 to connect configuration 18 is connected to drill string 8. First guide means 22 enable axially positioning radial drilling drive 16 in a substantially vertical direction. Second drive 24 with second clamping means 26, for example the top drive with a 30 threaded connection, is in the illustrated embodiment connected to the pipe section 10 that is to be connected to drill string 8. Second guiding means 28 enable positioning 13 drive 22 in a substantially direction allowing co-operation with first drive 16.

Fluid supply system 30 supplies drilling fluid to drilling system 4, and in the illustrated embodiment 5 specifically to drive 16. The other drive may also comprise a fluid supply system. Fluid supply system 30 comprises a first and second fluid chamber 32, 34. Fluid supply system 30 can be any conventional and/or commercially available fluid supply system.

10 When drilling borehole 12 drilling system 4 advances drill string 8 in an underground formation using drill bit 14. Drill string 8 is connected to radial drilling device 16 by first clamping means 18 and may be rotated by first drive 16. In this embodiment the drill string 8 may be 15 rotated by first drive 16 while second drive 24 is connected to additional pipe section 10 that is to be connected to drill string 8. After connecting pipe section 10 to drill string 8 second drive 24 starts rotating drill string 8. In a next step first drive 16 is repositioned in an axial 20 direction away from the drill floor. When the axial drilling device nears the drill floor, so there is a need for a new pipe section, the radial drilling device is connected to the top of drill string 8. After again clamping drill string 8 at the new position first drive 16 takes over the rotation. 25 The second top drive is ready to get an additional pipe section 10 that also needs to be connected to drill string 8 while drill string 8 is advancing into borehole 12.

Another embodiment drilling rig 42 (Fig. 1 B) comprises alternative drilling system 44. System 44 30 comprises a first drive 16 associated with first stationary and rotatable housing configuration 18 comprising first clamping means 20. In this embodiment second drive 46 is associated with second stationary and rotatable housing 14 configuration 48 comprising second clamping means 50. In the illustrated embodiment drilling system 44 is provided with a second fluid supply system 52 for the second configuration 48. First configuration 18 is guided by guiding means 22 5 while second configuration 48 is guided by second guiding means 54. When drilling borehole 12 alternative drilling system 44 advances drill string 8 in an underground formation using drill bit 14. In system 44 first and second configuration 18, 48 take over in a so-called "hand-over-10 hand" approach. First, drill string 8 is supported by first configuration 18. When configuration 18 is about to reach platform 6 the second configuration 48 positions pipe section 10 and connect section 10 to drill string 8. First configuration 18 is released or in other words unclamps and 15 second configuration 48 takes over the clamping and rotating functions. Then first configuration 18 is ready to get a further additional pipe section 10. Configuration 18, 48 (Fig. 2 A-C) comprises stationary housing 56 and rotatable housing 58. Rotatable housing 58 rotates relative to 20 stationary housing using first and second bearings 60, 62.

Rotatable housing 58 is rotated using gear 64 by the first drive 16. In this embodiment drive 16 is a so-called rotational drive. Clamping element 86 is activated by supporting element 84 when the elevator shoulder 48 makes 25 contact with insert 98 of support element 84 and the weight is supported by configuration 18. Additional clamping force can be generated by moving clamping actuator 68 in an axial direction A.

In the illustrated embodiment mechanism 66 30 comprises a first link 70 that with hinge 72 is connected to second link 74. Second link 74 is connected with hinge 76 to third link 78. At the upper part third link 78 is connected with hinge 80 to fourth link 82. First clamping element 84 15 supports drill string 8. Fourth link 82 is connected to clamping element 86. Clamping element 86 is functionally connected to first clamping element 84 with lever 90 and coupling element 92, 94. Together with mechanism 66 clamping 5 elements 84, 86 establish first clamping means 96.

When drill string 8 provides a downward axial force on clamping element 84 at insert 98 lever 90 intends to rotate around joint or hinge 100 second clamping element 86 is forced against drill string 8 with increased force.

10 This constitutes a self-supporting structure.

First seal 102 seals drill string 8 against rotatable housing 58. In fact, first seal 102 is pressed against the drill pipe 8 by the clamping element 86.

Clamping element 86 is equipped with an insert 104. First 15 seal 102 is pressed against the drill string by insert 104 that is mounted on element 86. Second seal 108 comprises first/bottom and second/upper seal units 110, 112. Optionally, between units 110, 112 a number of sealing rings 114 placed in series is provided. It will be understood that 20 other sealing components can also be applied in addition to, or alternative to, seal unit 110, 112 and sealing rings 114. Sealing part 110 comprises fluid channel 116 for providing fluid to the inner part of drill string 8. First link 70 rotates with rotatable housing 58 relative to stationary 25 housing 56 over bearing 118. Additional bearing 120 of stationary housing 56 provides support to rotatable housing 56. Clamping mechanism moves between an unclamped state (Fig. 3 A) and a clamped state (Fig. 3 B) by moving first link 70 in an axial direction. Bottom part 122 with 30 constructional part 124 of rotatable housing 58 rotates relative to stationary housing 56 over bearing 120.

In the illustrated embodiment hinge 76 comprises a number of pins 126 and corresponding openings 128 (Fig. 4 A- 16 D and 5). In this embodiment other hinges also comprise a number of pins and openings or holes.

The present invention is by no means limited to the above described embodiments thereof. The rights sought 5 are defined by the following claims within the scope of which many modifications can be envisaged. For example, the indirect sealing approach can also be used in conventional drilling systems.

17

Clauses 1. Radial clamping/sealing system for a drilling system for (semi)-continuous drilling a borehole, comprising: 5 - a stationary housing; a rotatable housing comprising first clamping means for clamping and holding a drill string with a drill bit in a substantially radial direction of the drill string; and 10 - a first drive for rotating the rotatable housing with the drill string, wherein the rotatable housing comprises a first direct seal between the clamping means and the drill string, and a second indirect seal between the rotatable 15 housing and the stationary housing.

2. Drilling system for (semi)-continuous drilling a borehole, comprising a radial clamping/sealing system according to clause 1 as first clamping means, and 20 further comprising: a second drive for rotating the drill string comprising second clamping means for clamping the drill string; guiding means for enabling a substantially axial 25 movement of at least one of first and second drives; and control means controlling the first and second drive such that in operation the drill string is substantially continuously driven by the first 30 and/or second drives.

18 3. Drilling system according to clause 2, wherein the guiding means are configured such that at least one of the first and second clamping means is capable of positioning an additional pipe section on the drill 5 string.

4. Drilling system according to clause 3, wherein both the first and second clamping means are capable of positioning the additional pipe section on the drill 10 pipe.

5. Drilling system according to clause 2, 3 or 4, wherein the first clamping means comprise a number of clamping parts that move relative to each other in at least a 15 radial direction for clamping and unclamping the drill string or pipe section.

6. Drilling system according to one or more of the foregoing clauses, wherein the first and/or second 20 seals comprise seal parts. 1 2

Drilling system according to one or more of the foregoing clauses, wherein the first and/or second seals comprise sub-seals.

25 2

Drilling system according to one or more of the foregoing clauses, further comprising a lever for increasing the clamping force of the first and/or second clamping means on the drill string or pipe 30 section.

19 9. Drilling system according to clause 8, further comprising a self-supporting structure comprising the lever such that a load acting downward in an axial direction of the drill string increases the clamping 5 force.

10. Drilling system according to one or more of the foregoing clauses, wherein the first and/or second clamping means comprise inserts enabling the handling 10 of different drill pipe dimensions.

11. Drilling rig comprising a drilling system according to one or more of the foregoing clauses.

15 12. Method for (semi)-continuous drilling a borehole, comprising: providing a clamping/sealing system and/or a drilling system and/or a drilling rig according to one or more of the foregoing clauses; 20 - clamping the drill string with the first clamping means; rotating the drill string with the first drive; and clamping an additional pipe section with the second clamping means and connecting the pipe 25 section to the drill string.

13. Method according to clause 12, wherein the additional pipe section is connected in continuous or semi-continuous operation.

20 14. Method according to clause 12 or 13, further comprising the steps of: rotating the drill string with the second drive; and 5 - clamping a further additional pipe section with the first clamping means.

15. Method according to clause 12, 13 or 14, wherein clamping the drill string comprises moving the lever to 10 increase the clamping force of the clamping means on the drill string or pipe section.

16. Method according to one or more of the clauses 12-15, wherein clamping the drill string further comprises the 15 step of sealing the drill string.

Claims

A radial clamping / sealing system for a drilling system for drilling a borehole, comprising: 5. a stationary housing; - a rotatable housing comprising first clamping means for clamping and holding a drill pipe with a drill point in a substantially radial direction of the drill pipe; and 10. a first drive for rotating the rotatable housing with the drill pipe, wherein the rotatable housing comprises a first direct seal between the clamping means and the drill pipe and a second indirect seal between the rotatable housing and the stationary housing.

A drilling system for drilling a borehole comprising a radial clamping / sealing system as claimed in claim 1 as first clamping means, further comprising: 20. second clamping means for clamping the drill pipe; - a second drive for rotating the drill pipe cooperating with the second clamping means - guiding means for enabling a substantially axial movement of at least one of the first and second drives; and - control means for controlling the first and second drives such that in operation the drill pipe can be driven substantially continuously by the first and / or second drive. 30

3. Drilling system according to claim 2, wherein the guide means are configured such that at least the first clamping means are suitable for positioning an additional tube part on the hearing tube.

4. Drilling system according to claim 3, wherein both the first and second clamping means are suitable for positioning the additional tube part on the hearing tube.

5. Drilling system according to claim 2, 3 or 4, wherein the rotatable housing comprises a number of clamping elements that move relative to each other in at least a radial direction for clamping and releasing the hearing tube or tube part.

6. Drilling system as claimed in one or more of the foregoing claims, wherein the first and / or second seals 20 comprise sealing parts. Drilling system according to one or more of the preceding claims, wherein the first and / or second seals comprise sub-seals. 2 Drilling system according to one or more of the preceding claims, further comprising a lever for increasing the clamping force of the clamping means on the hearing tube.

The drilling system of claim 8, further comprising a self-supporting structure comprising the lever such that a load acting in a downward axial direction of the hearing tube increases the clamping force. 5

10. Drilling system as claimed in one or more of the foregoing claims, wherein the first and / or second clamping means comprise inserts for making it possible to handle different pipe diameters. 10

A drilling platform comprising a drilling system according to one or more of the preceding claims.

A method for drilling a borehole, comprising: 15. providing a clamping / sealing system and / or drilling system and / or a drilling platform according to one or more of the preceding claims; - clamping the hearing tube with the first clamping means; 20. rotating the hearing tube with the first drive; and - clamping an additional tube part with the second clamping means and connecting the tube part with the hearing tube. 25

The method of claim 12, wherein the additional tubular member is connected in a continuous or semi-continuous operation.

A method according to claim 12 or 13, further comprising the steps of: - rotating the hearing tube with the second drive; and 5. clamping a further additional tube part with the first clamping means.

A method according to claim 12, 13 or 14, wherein the clamping of the hearing tube comprises moving the lever 10 to increase the clamping force on the clamping means on the hearing tube or tube part.

16. Method as claimed in one or more of the claims 12-15, wherein the clamping of the hearing tube further comprises the step of sealing the tube.