TECHNICAL FIELD

The invention relates to the making or breaking of tubing strings, such as drill strings and casing strings, suspended in a well drilled or being drilled in the lithosphere.

BACKGROUND ART

In U.S. patent 3,559,739, an apparatus for providing continuous foam circulation in a well during making up or breaking a connection between tubulars of a string is disclosed. To enable circulation to continue while a tubular is connected to the tubing string or disconnected from the tubing string, a shell is provided enclosing a space where the connection is to be made or broken. When the upper end of the tubing string is opened, the flow via the top drive is taken over by a flow which enters or leaves the tubing string via a back-up conduit and a connecting chamber bounded by a shell in which the connection is being made up or broken out. To allow the entry of a tubular to be added into the connecting chamber or the removal of a tubular from the connecting chamber, while maintaining the flow through the open end of the tubing string, the connecting chamber can be divided in two portions by closing off a gate. Thus, the flow can be maintained via the high pressure back-up conduit and the lower portion of the connecting chamber while a tubular is brought into a position in-line with the tubing string or is transported away from above the tubing string.

Other examples of such an apparatus are disclosed in International

Patent Application WO 98/16716 and in WO 00/23686.

Although the principle of continuous drilling is known for a long time and, with increasing scarcity of natural resources, the incentive of drilling in challenging situations where an interruption of the drilling process may entail substantial problems such as hole instability, poor cuttings transport and stuck-pipe, has increased, making up or disconnecting connections in a connection chamber through which mud or foam flow is maintained has not been applied much, mainly because of the bulky nature of required

equipment. In particular, in commercially available equipment, the shell bounding the connection chamber, which must be able of withstanding pressures in the order of magnitude of 500 bar, constitutes a costly, large and heavy construction. SUMMARY OF THE INVENTION

It is an object of the present invention to provide a solution which allows making up and breaking out connections between tubulars of a drill string or a casing string in a lighter and more compact connecting chamber of a system that allows continuous circulation and translation and rotation of the drill string.

According to one aspect of the present invention, this object is achieved by providing an implement according to claim 1.

Because the jaws can be operated by rotation of an operating sleeve about a centre line of the opening, the implements can be of a radially small construction. This allows the connection shell bounding the connection chamber to be of a slender design. This is particularly advantageous in view of the high internal pressure the connection shell should be able to resist. By limiting the cross-sectional size of the connection chamber, the forces exerted onto the operating shell are reduced accordingly. A more compact connection shell is particularly advantageous for accommodating equipment and room for allowing continuous rotation and translation while making-up a

connection.

The invention can also be embodied in an apparatus according to claim 12, which includes such an implement.

Particular embodiments of the invention are set forth in the dependent claims.

Further details, objects, features and advantages of the invention are described with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1A-1M are schematic side views of an example of an apparatus according to the invention during successive stages of operation; and Fig. 2 is a schematic side view in cross section, along the line II -II in Fig. 3, of a first example of an implement according to the invention in open and closed conditions;

Fig. 3 is a schematic top plan view in cross-section along lines Ilia (sections al and a2) and Illb (section b) of the implement shown in Fig. 2 in open (sections al and b) and closed (section a2) conditions;

Fig. 4 is a schematic side view in cross section, along line IV- IV in Fig. 5, of a second example of an implement according to the invention with jaws in retracted and engaging positions;

Fig. 5 is a schematic top plan view in cross-section along lines Va

(section a - top half) and Vb (section b - bottom half) of the implement shown in Fig. 2 in engaged (right half) and retracted or disengaged (left half) conditions; and

Fig. 6 is a schematic side view in cross section of a third example of an implement according to the invention with jaws in retracted (left half) and engaged (right half) positions.

MODES FOR CARRYING OUT THE INVENTION In Figs. 1A-1M, an apparatus according to the invention is

schematically shown in successive stages of operation. As such, these stages of operation are the same as the stages of operation shown and illustrated in WO 00/23686 in which also further details of examples of apparatuses for performing such an operation are shown. The stages are described to provide an example of a context of operation of implements according to the invention and the functionality of such implements. Moreover, with the inclusion of one or more implements according to the present invention, such an apparatus also forms an embodiment of the invention.

The apparatus has a connector 9 suspended for retaining a tubular 1 in a position axially projecting from the connector 9, an upper gripping implement in the form of a clamp 7 (see Figs. II- 1M) which is adapted and supported for taking up axial and rotational loads and a lower, second clamp 27 adapted and supported for taking up axial and rotational loads. The connector 9 and the clamps 7, 27 are vertically movable independently of each other. Figs. 4 and 5 show an example of such a clamp in more detail. A main high pressure conduit 13 is connected to the connector 9 for allowing circulation to and through the tubular 1 (or any other tubular) connected to the connector 9. Below the connector 9, a connecting shell 17 is located. The connecting shell 17 bounds a connecting chamber 18 and has an upper passage 19 and a lower passage 20 on diametrically opposite sides for receiving tubulars. The passages 19, 20 are provided with seal implements 21, 22 for sealing off the passages 19, 20 against tubulars extending through the passages. Fig.6 shows an example of such a seal implement in more detail. In the connecting chamber 18, a gate implement 23 for separating an upper portion 24 of the connecting chamber 18 from a lower portion 25 of the connecting chamber 18 is provided. Figs. 2 and 3 show an example of such a gate implement in more detail. A high pressure back-up conduit 26

communicates with the lower portion 25 of the connecting chamber 18.

The clamp 7 is adapted and positioned for holding a tubular 1 projecting from above into the upper portion 24 of the connecting chamber 18 and can take up both axial and rotational loads. The second clamp 27 is for holding the tubing string 2 by engaging a tubular projecting from below into the lower portion 25 of the connecting chamber 18. For holding the tube string 2 while the second clamp 27 is released to allow it to be moved axially along the tube string 2, a further clamp (not shown) below the clamp 27, which may be of a similar design, is provided. This further clamp is vertically movable as well to allow continuous axial movement of the tube string 2 while the second clamp 27 is reversed to its initial position. The clamp 27 and the further clamp below clamp 27 may also be arranged for being driven in rotational sense about the drill string axis and for transmitting torque to the drill string to keep it rotating while a next tubing is connected.

Usually, the tubulars of a tubing string have an increased thickness at the coupling ends. As the tubing string 2 is lowered into the well or pulled out of the well, these portions having an increased thickness pass through the seal implements 21, 22 in the passages 19, 20 of the connecting shell 17. Furthermore, it is advantageous if the opening through the seal implement 21 of the upper passage 19 is wide when a tubular is to be inserted into the opening 19. Therefore, the seal implements 21, 22 for sealing off the passages 19, 20 of the connecting shell 17 are expandable from a receiving condition for allowing insertion of a tubular into the connecting chamber 18 to an expanded condition for sealing off the passage against a tubular axially projecting therethrough into the connecting chamber 18. In retracted condition, the seal implements 21, 22 do not need to perform a sealing function against high pressure in the connecting chamber.

In each of the high pressure conduits 13, and 26 valves 29, 30 for closing off the high pressure conduits 13, and 26 are provided. The valves 29, 30 are each bypassed by a bypass 31, 32 communicating with the respective one of the high pressure conduits 13, 26. In each of the bypasses 31, 32 a bypass-valve is provided. Furthermore, a low pressure conduit 35

communicates with the upper portion 24 of the connecting chamber 18. In this low pressure conduit 35 a valve 36 is provided for closing of the low pressure conduit 35.

The valves in the bypasses 31, 32 are substantially smaller than the valves 29 and 30 in the high pressure conduits 13, 26. Of these valves, only the valves in the bypasses 31, 32 are capable of being operated while a full operating pressure drop over the respective valve exists or is formed as the valve is closed. This allows using large valves 29, 30 in the high pressure conduits 13, 26 which can be opened and closed only while no substantial pressure drop over the valve exists or is caused to exist. Such valves are substantially less costly than large valves which can be operated at a full operating pressure drop over the valve. The bypasses 31, 32 allow to even out pressure differences before or while the valves 29, 30 in the high pressure conduits 13, 26 are operated. However, to fill and empty the connecting chamber 18 or at least the upper portion 24 thereof via the bypasses would take a long time. This problem is avoided by filling, or emptying as the case may be, the connecting chamber 18 or at least its upper portion 24 via the low pressure conduit 35 which is of a substantially larger internal cross- section than the bypasses 31, 32. Accordingly, the bypasses 31, 32 only serve for topping up the connecting chamber up to the pressure in the respective high pressure conduit 13, 26.

In order to allow emptying of the lower portion 25 of the connecting chamber 18 as well, a low pressure conduit 37 communicating with the lower portion 25 of the connecting chamber 18 of the connecting shell 17 is provided. This low pressure conduit 37 is provided with a valve 38 for closing off that conduit 37.

In combination with pumps 39, 40 (Fig. 1M), the valves 36, 38 in the low pressure lines 35, 37 form a flow control structure for controlling the flow through the low pressure lines 35, 37. Furthermore, a control system 41 (Fig. 1M) is provided which is operatively connected to the valves 29, 30 in the high pressure conduits 13, 26, to the bypass valves and to the flow control structure 36, 38, 39, 40. The control system 41 is programmed for each time controlling the flow control structure 36, 38, 39, 40 to fill up at least the upper portion 24 of the connecting chamber 18 in the connecting shell 17 via the low pressure conduit 35 before opening of the bypass valve 31. Thus, it is ensured that each time only a limited volume of fluid has to pass the bypass 31 to build up the required pressure in the upper portion 24 of the connecting chamber 18.

Next, a cycle of adding a tubular 1 to a tubing string 2 is described. Before starting the cycle of connecting a tubular 1 to a tubing string 2, the apparatus is operating in a condition in which the valve 30 is closed and the valve 29 is opened so that fluid (in this example mud) passes via the main high pressure conduit 13 and the connector 9 to the tube string 2, as is represented by arrows 42, 43. The connector 9 has descended to a position at least partially within the connecting chamber 18 of the connecting shell 17 in which the upper end of the tubing string 2 is located in the lower portion 25 of the connecting chamber 18 (Fig. 1A). The seal implements 21, 22 of the passages 19, 20 are in a non-sealing, retracted condition and the gate implement 23 is open.

Then, the seal implements 21, 22 of the passages 19, 20 are expanded into a sealing, expanded condition and the lower clamp 27 is closed to engage the tubing string so that the situation shown in Fig. IB is obtained.

Subsequently, the connecting chamber 18 is filled with mud via the low pressure conduits 35, 37 by opening the valves 36, 38 as is represented in Fig. 1C by arrows 44, 45. After the connecting chamber 18 has been filled or has almost been filled, the valves 36, 38 are closed again to prevent high pressure from reaching the low pressure conduits, and the valve in bypass 31 is opened so that the pressure in the connecting chamber 18 rises to the operating pressure of typically 250-500 bar prevailing in the high pressure conduits 13, 26 (arrow 46). After the pressure drop over the valve 30 in the back-up high pressure conduit 26 has been equalised, the valve 30 is opened.

In-between, the flow of fluid through the conduit 13 and the tubing string 2 still continues as is represented by the arrows 42, 43. Then, the connector 9 is disconnected from the tubing string 2 as is shown in Fig. ID. Since the pressure in the connecting chamber 18 is essentially equal to the pressure in the passage through the connector 9 and the pressure in the tubing string 2 near its upper end, the flow to the tube string 2 still continues, now via the connecting chamber 18. A portion of the flow via the main high pressure conduit 13 may be replaced by flow through the back-up high pressure conduit 26. This portion becomes substantial at least when the connector 9 is moved further up and away from the tubing string 2 until a position above the level of the gate 23, as is represented in Fig. IE by the reduced length of the arrows 42', 43' and the addition of arrow 46.

Next, as shown in Fig. IF, the gate implement 23 is closed, so that the flow through the main high pressure conduit 13 is completely replaced by a flow through the back-up high pressure conduit 26 (arrow 46).

After the gate implement 23 has been closed, the valve 29 in the main high pressure conduit 13 is closed and, subsequently, the upper connecting chamber portion 24 is drained via the low pressure conduit 35

communicating therewith by opening the valve 36 and activating the pump 39 (arrow 47).

Then, the seal implement 21 in the upper passage 19 is retracted to facilitate withdrawal of the connector 9 from the connecting chamber 18 and the connector 9 is withdrawn from the connecting chamber 18 as is shown in Fig. 1H. In the meantime, the flow of fluid through the tubing string 2 is maintained via the back-up high pressure conduit 26 and the lower portion 25 of the connecting chamber 18 under the gate implement 23 (arrow 46).

In a next stage, shown in Fig. II, a tubular 1 to be added to the tubing string 2 has been connected to the connector 9 and is being lowered into the connecting chamber 18. Once the coupling portion at the lower end of the new tubular 1 is completely within the connecting chamber 18, the seal implement 21 in the upper passage 19 of the connecting shell 17 is expanded to seal against the stem of the new tubular 1 (Fig. 1J). As is also shown in Fig. 1J, the upper portion 24 of the connecting chamber 18 is filled again via the low pressure conduit 35 communicating therewith by activating the pump 39 (arrow 48). The valve 36 has been left open since the draining of the upper portion 24 of the connecting chamber 18. After the connecting chamber 18 has been filled sufficiently, the valve 36 is closed.

Then, the main high pressure conduit 13 communicating with the new tubular 1 and the upper portion 24 of the connecting chamber 18 is brought under pressure by opening the valve 33 in the bypass 31 around the valve 29 in the high pressure hose 14 in-line with the main high pressure conduit 13 (arrow 49).

Then, as is shown in Fig. IK, the gate implement 23 and the valve 29 in the high pressure conduit 13 are opened. Since the pressures on opposite sides of the gate implement 23 are equalised each time before the gate implement 23 is opened, the high operating pressure is applied to the gate only while the gate implement 23 is closed and not while it is being opened or closed, so that wear of the gate is reduced.

Thus, a portion of the fluid flow is again led via the main high pressure conduit 13 (arrows 42', 43') and the flow via the back-up high pressure conduit 26 is reduced accordingly (arrow 46').

Subsequently, the connector 9 is lowered until the lower end of the new tubular 1 is closely above the upper end of the tubing string 2 (Fig. 1L). In this position, the tubular 1 is clamped by the clamp 7. Axial movement of the new tubular 1 is now controlled by the axial movement of the clamp 7, the connector 9 merely following such movements. The clamp 7 accurately controls the axial stabbing force applied to the tubular 1 as it is lowered and engages the upper end of the tubing string 2 (Fig. 1L).

Next, the connection between the tubular 1 and the tubing string 2 is made up, for instance by gripping the outer circumference of the tubular 1 and of the tubing string 2 at the clamps 7, 27 and twisting the tubular 1 relative to the tubing string 2 until the connection has been made up with the required torque. Preferably the tubing string 2 is continuously rotated and lowered by driving rotation and axial displacement of lower clamp 27, so that drilling is not interrupted. Then, the fluid flow, which has not been

interrupted, again runs entirely via the main high pressure conduit 13 (arrows 42, 43) and the valve 30 in the high pressure back-up conduit 26 as well as its bypass valve 34 are closed. Next, the connecting chamber 18 is drained by opening the valve 38 in the low pressure conduit connected to the lower portion of the connecting chamber 18 (arrow 50).

The clamps 7, 27 are released and after the connecting chamber 18 has been drained, the seal implements 21, 22 in the passages 19, 20 in the connecting shell 17 are retracted again to allow continuation of the lowering of the tubing string 2. Since the fluid is removed from the connecting chamber 18 after make-up of the connection and before the connection leaves the connecting chamber 18, the lower seal implement 22 does not have to fulfil a sealing function while the tubing string 2 is being lowered and the joint, which is usually of a larger thickness than the sections between the joints, passes through the lower passage 20 in the connecting shell 17.

However, especially if the tubing string is reasonably smooth on its outside, fluid may be left in the connecting chamber 18 and the connection between successive tubulars can be passed through the lower seal implement 22 of the connecting shell 17 while this seal seals against the tubing string 2. Thus, the need of draining and refilling the connecting chamber 18 can be obviated.

In Figs. 2 and 3, an example of an implement according to the invention in the form of a gate implement 23 is shown. In Fig. 2, the gate implement 23 is shown in open condition and in closed condition. The open condition is shown to the left of a centre line 60 of the implement 23 and the opening 61 and the closed condition is shown to the right of the centre line 60. In Fig. 3, the implement 23 is shown in the open condition in the drawing areas designated as section al and section b and in the closed condition in the drawing area designated as section a2. Sections al and a2 have been taken along line Illa-IIIa in Fig. 2 and section b has been taken along line Illb-IIIb in Fig. 2.

The gate implement 23 allows controlling the opening 61 for receiving a tubular of a drill string, for closing off and opening the opening 61, the implement 23 has carrier sleeves 62, 63 surrounding the opening 61. Jaws 64-66 of the implement 23 are carried by the carrier sleeves 62, 63 and hinged to the carrier sleeves 62, 63 so as to be pivotable into and out of the opening 61 about axes 83 outside of the opening 61 and parallel to the central axis 60 of the opening 61. The implement 23 further has an operating sleeve 67 rotatably suspended relative to the carrier sleeves 62, 63 so as to be rotatable relative to the carrier sleeves 62, 63 about the central axis 60 of the opening 61 and coaxial therewith. To this end, flanges 68, 69 of the carrier sleeves 62, 63 are enclosed between rings 70, 71 of the operating sleeve 67 that are screwed into a cylindrical part 72 of the operating sleeve 67. The jaws 64-66 are coupled to the operating sleeve 67 for urging the jaws 64-66 into and out of the opening 61 in response to rotation of the operating sleeve 67 relative to the carrier sleeves 62, 63.

Since the operating sleeve 67 and the jaws 64-66 are arranged concentrically around the opening 61, a construction for shutting off and clearing the opening 61 is obtained that is very compact in radial direction over its full circumference. This allows the implement 23 to be rotatably accommodated in a connecting chamber 18 that is accordingly compact in directions transverse to the drill string 2. This in turn allows the connecting shell 17 to be of a compact construction and to be of a relatively light construction, because a reduced cross-sectional size accordingly reduces the forces to which the connecting shell 17 is subjected as a result of the high fluid pressure in the connecting chamber 18.

Opening and closing of the gate implement 23 can be controlled by controlling the position of the operating sleeve 67 relative to the carrier sleeves 62, 63 in rotational sense, for instance using a drive 56. This may for instance be a drive as disclosed in WO99/34089 or an electrically or hydraulically powered motor. Rotation of the operating sleeve 67 relative to the carrier sleeves 62, 63 only has to be enabled to allow and control rotation back and forth over a limited angle. Depending on the design of the cams, this angle may for instance be in a range of 20 to 45 degrees.

The gate implement 23 further has an outer sleeve 73 via which the gate implement 23 can be suspended in the connecting shell 17. The operating sleeve 67 is rotatably suspended inside the outer sleeve 73 so as to be rotatable relative to the outer sleeve 73 about the central axis 60 of the opening 61 and coaxial therewith. To this end, the operating sleeve 67 is arranged between bearings 74, 75 screwed into the outer sleeve 73. The carrier sleeves 62, 63 are rotatably suspended to the outer sleeve 73.

In the present example, sets of three jaws 64-66 distributed in circumferential sense around the opening 61 are provided. By providing sets of at least three jaws distributed in circumferential sense around the opening, relatively small jaws can be provided, which occupy relatively little space in radial direction when retracted, which further contributes to the relatively small dimensions of the gate implement.

In the gate implement 23 according to the present example, the jaws 64-66 close off the opening 61 when in a most inward position. In the most inward position, an inner set of the jaws 66 extends further inwardly than an outer set of the jaws 64, 65, which jaws 64, 65 close off outer portions of the opening 61 not closed off by the inner set of the jaws 66. Because the jaws 64- 66 comprise inner and outer jaws which, in combination provide for fully closing off the opening 61, the implement can be of small dimensions in radial direction, which further contributes to allowing compact radial dimensions of the gate implement 23. At the expense of a radially larger tool, jaws each covering the entire span from the outside of the opening to the central axis could be provided.

The inner set of the jaws 66 is located axially between the outer sets of the jaws 64, 65, so that the inner jaws 66 are firmly held between the outer jaws 64, 65 and supported towards the outside of the opening 61 via the overlapping outer jaws 64, 65.

The operating sleeve 67 and the jaws 64-66 have cam surfaces 76-81. The cam surfaces 79-81 of the operating sleeve 67 engage cam surfaces 76-79 of the jaws 64-66 for urging the jaws 64-66 into the opening 61 when the operating sleeve 67 is rotated relative to the carrier sleeves 62, 63 in a counter clockwise sense of rotation around central axis 60 as indicated by arrow 93 in Fig. 3 from a position shown in sections al and b of Fig. 3 to a position shown in section a2 of Fig. 3. The cam surfaces 78 of the jaws 66 and the cam surfaces 81 of the operating sleeve 67 engaging the cam surfaces 78 of jaws 66 are shaped for pressing the jaws 66 against each other when the operating sleeve 67 reaches an end position shown in section a2 in Fig. 3, so that an effective sealing closure is achieved along contact surfaces of the jaws 66 that are pressed against each other. For an effective closure, the jaws 64- 66 may be provided with resilient, e.g. elastomeric sealing material. The cam surfaces 76, 77 of the jaws 64, 65 and the cam surfaces 79, 80 of the operating sleeve 67 engaging the cam surfaces 76, 77 of the jaws 64, 65 are shaped such that the jaws 64, 65 are urged into pre-defined positions which are reached before the operating sleeve 67 reaches the end position shown in section a2 in Fig. 3 and not urged further as the operating sleeve 67 moves further over a last portion of the movement to the end position shown in section a2 in Fig. 3 pressing the jaws 66 are pressed against each other. Thus, it is ensured that on the one hand the outer jaws 64, 65 are brought in pre-defined end positions while pressing the inner jaws 66 against each other is not impaired by interaction between the operating sleeve 67 and the outer jaws 64, 65. The jaws 64-66 are each hinged about a pin 84 coaxial with one of the axes 83 relative to the carrier sleeves 62, 63 for rotation about one of the axes 83. Outer ends of the pins 84 are fixed to the carrier sleeves 62, 63.

The inner ones of the jaws 66 have hollow curved surfaces 85 that, when the jaws 66 are in a most outward position, face the opening 61 and have an axis of curvature coinciding with or parallel to the central axis 60 of the opening 61. When the inner jaws 66 are in the most inward position, the hollow surfaces 85 each sealingly contact a correspondingly curved opposite convex surface 86 of an adjacent one of the inner jaws 66. Because the surfaces 85 of the jaws 66 that face the opening 61 when the jaws are in the open condition are hollow. The curvature of these faces follows, at least to some extent, the curvature of the contour of the opening 61. Thus, the jaws 66 extend closely around the opening 61 when in open condition and can be compact in radial direction, thereby further contributing to small overall radial dimensions of the implement 23.

The outer ones of the jaws 64, 65 have hollow curved sides 91. When the outer jaws 64, 65 are in a most outward position, the hollow curved sides

91 of the jaws 66 are facing towards the opening 61. When the outer jaws 64, 65 are in the most inward positions, the outer ones of the jaws 64, 65 each overlap an inner one of the jaws 66 along the hollow curved side 91 thereof. Because the surfaces 91 of the outer jaws 64, 65 that face the opening 61 when the jaws are in the open condition are hollow as well, the curvature of these faces follows, at least to some extent, the curvature of the contour of the opening 61. Thus, also the outer jaws 64, 65 extend closely around the opening 61 when in open condition and can be compact in radial direction, thereby further contributing to small overall radial dimensions of the implement 23. Furthermore ends 92 of the outer jaws 64, 65 facing away from the respective hinging axis 83 thereof are preferably shaped to each overlap an inner one of the jaws 66 along a portion of the hollow curved surface 85 thereof, so that an overlapping seal is obtained where end surface

92 of the outer ones of the jaws 64, 65 extend closely along sides 85 of outer inner of the jaws 66. Thus a reliable sealing is also obtained along side portions of the inner and outer jaws 64-66 that are not in abutment with other ones of the jaws 64-66 at the same level when the jaws 64-66 are in the most inward positions. In Figs. 4 and 5, a second example of an implement according to the invention in the form of the clamp 7 of Figs. II- 1M is shown in more detail. Clamp 27 performs a similar function and may be of the same design as clamp 7. In Figs. II- 1M, the clamps 7, 27 are arranged outside of the connecting shell 18, where a small radial size of the clamps would be less critical. However, in many applications, it is desirable that the clamps 7, 27 for holding the tubular to be connected or disconnected and the (remainder of) the tube string are located inside the connecting shell 18 for engaging the tubulars at tool joints at the ends of the respective tubulars. For avoiding the need of providing different clamps for use inside and outside of the connecting shell 18, it is advantageous if the same clamps can be used, no matter whether the clamps 7, 27 are to be arranged inside or outside of the

connecting shell 18. To the left of the centre line 160 of the opening 161, the clamp 7 is shown in open condition, with jaws 164 retracted out of the

(contour of the) opening 161. To the right of the centre line 160 of the opening 161, the clamp 7 is shown in gripping condition for engaging an outer surface of tubing 2 (see Fig. 4) extending through the opening 161, with jaws 164 pressed into the opening 161. In Fig. 5, the clamp of Fig. 4 is moreover shown along two sectional planes, the top half showing a cross-section along line Va- Va in Fig. 4 and the bottom half showing a cross-section along line Vb-Vb in Fig. 4.

The clamp 7 according to the present example has a carrier sleeve 162 surrounding the opening 161. The carrier sleeve 162 is composed of an upper carrier sleeve part 193, a lower carrier sleeve part 194 and guides 195 interconnecting the upper and lower carrier sleeve parts 193, 194. Between the upper carrier sleeve part 193 and the lower carrier sleeve part 194, a transfer sleeve 196 is arranged and guided by the guides 195 for movement in axial directions of the opening 161, so as to be reversibly movable relative to the carrier sleeve 162 in the axial directions while being restrained from rotating about the central axis 160 of the opening 161.

The jaws 164 are carried by the lower carrier sleeve part 194 of the carrier sleeve 162 and guided relative to the carrier sleeve 162 so as to be radially movable into and out of the opening 161. To this end, the lower carrier sleeve part 195 has guide slots 197 engaging projections 198

projecting downwards from the jaws 164. Also in this embodiment, an operating sleeve 167 is rotatably suspended relative to the carrier sleeve 162, so as to be rotatable relative to the carrier sleeve 162 about a central axis 160 of the opening 161. The operating sleeve 167 has an inner thread 199 and the transfer sleeve 196 has an outer thread 200 engaging the inner thread 199 of the operating sleeve 167 for driving axial displacement of the transfer sleeve 196 relative to the carrier sleeve 162 in response to rotation of the operating sleeve 167 relative to the carrier sleeve 162. The position in rotational sense of the operating sleeve 167 relative to the carrier sleeve 162 can for instance be controlled using a drive 156 as schematically shown, which may be a drive as disclosed in WO99/34089 or an electrically or hydraulically powered motor.

The transfer sleeve 196 engages the jaws 164 for urging the jaws 164 radially into the opening 161. By rotating the operating sleeve 167, the transfer sleeve 196 can be displaced axially downwards as a result of screwing engagement of its outer thread 200 with the inner thread 199 of the rotating operating sleeve 167. By rotating the operating sleeve 167 in the opposite sense, the jaws 164 are released. The jaws 164 may for instance be biased radially out of the opening by spring force or just be left free to be pushed back by for instance relative large portions of tubulars 2 urged through the opening 161.

For transferring axial movement of the transfer sleeve 196 into radial movement of the jaws 164, the jaws 164 have wedge surfaces 152 in

engagement with wedge surfaces 153 of the transfer sleeve 196.

The clamp 7 further has an outer sleeve 173 that is fixedly mounted to a support structure of the apparatus for connecting and disconnecting tubulars. The carrier sleeve 162 is rotatably suspended from the outer sleeve 173 so as to be rotatable relative to the outer sleeve 173 about the central axis 160 of the opening 161. The carrier sleeve 162 is also coupled to the outer sleeve 173 via a drive 155 for controlling rotation of the carrier sleeve 162 relative to the outer sleeve 173. The drive 155 can for instance be a drive as disclosed in WO99/34089 or by an electrically or hydraulically powered motor. Such rotation may for instance serve for making-up or breaking a connection between tubulars of a drill string and for continuous rotation while making-up or breaking a connection between tubulars of a drill string.

In Fig. 6, a third example of an implement according to the invention in the form of a sealing implement 21 is shown. To the left of centre line 260, the implement 21 is shown in an operating condition with a jaw forming a seal 264 in retracted condition for allowing joints of a string 202 to pass axially through the seal 264. To the right of centre line 260, the implement 21 is shown in an operating condition with a seal 264 urged into the opening 261 in sealing engagement with an outer surface of a tubular of a drill string 202 for sealing off the opening 261 against the outer surface of a tubular of a drill string 202. The same principle can be applied for sealing against an outer surface of a tubular to be connected to or disconnected from a drill string. The outer sleeve 273, the operating sleeve 267 and the carrier sleeve 262 are identical to corresponding parts of the second example shown in Figs. 4 and 5. The transfer sleeve 296 differs from the transfer sleeve 196 shown in Figs. 4 and 5 in that, instead of wedge surfaces 153, concave surfaces 253 are provided that are curved inwardly from lower outer edges thereof for both axially compressing the seal 264, causing it to bulge radially inwardly, and directly deforming the seal 264 radially inwardly into the opening 261. The seal 264 is of elastomeric material and has convex curved surfaces 252 facing the concave surfaces 253 of the transfer sleeve 296. The seal 264 is fixedly mounted to a lower part 294 of the carrier sleeve 262 and can be deformed from an unloaded condition shown to the left of the centre line 160 to an inwardly deformed condition shown to the right of the centre line 160 in response to being axially compressed and inwardly urged by axial downward displacement of the transfer sleeve 296. The position of the operating sleeve 267 relative to the carrier sleeve 262 can be controlled in a similar manner as described with respect to Figs. 2-5.

It is noted that within the framework of the present invention as set forth in the claims, many other variants are conceivable. For instance the jaws may be partially made of elastomeric material, for instance only along surfaces that are to be brought in sealing contact with a tubular or with an adjacent one of the jaws. Instead of a transfer sleeve, separate transfer members can be provided. Also, while several features are described herein as part of the same or separate embodiments, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. For instance, displacement of jaws that are suspended for rotation about a centre line as shown in Figs. 2 and 3 may also be driven via an axially movable transfer member and displacement of jaws guided for straight radial displacement, as shown in Figs. 4 and 5, or arranged for displacement by deformation, as shown in Fig. 6 may also driven by cam surfaces rotating about the centre line of the opening.