Device arranged for attaching a pipe stem on a tubular body

Abstract

An attachment device for an element is made to be arranged on a downhole tubular body, in which an end portion of a sleeve, which is arranged to surround a portion of the tubular body, comprises an attachment portion. The attachment portion comprises at least one clamping element arranged for axial displacement by the abutment of an abutment surface against a conical abutment portion of a surrounding adapter sleeve.

Claims

1. An attachment device for a pipe stem comprising one or more radially projecting function elements made to be arranged on a downhole tubular body, wherein an end portion of the pipe stem or an end portion of a supporting sleeve abutting the pipe stem, which is arranged to surround a portion of the tubular body, is provided with an attachment portion which includes at least one clamping element arranged for inward radial displacement by the abutment of an abutment surface of the attachment portion against a conical abutment portion on a surrounding adapter sleeve, wherein an external locking portion of the end portion is formed as several catches extending in the circumferential direction of a jacket surface of the attachment portion and being arranged to engage corresponding engagement elements projecting inwards on the adapter sleeve, the circumferential extent of the catches being defined by slits penetrating at least the locking portion and extending substantially in the axial direction of the attachment portion.

2. The attachment device in accordance with claim 1, wherein the clamping element is formed as a lip projecting in the axial direction from the locking portion.

3. The attachment device in accordance with claim 2, wherein the lip has a thickness gradually decreasing in a direction from the locking portion as an inward contact surface is conical.

4. The attachment device in accordance with claim 1, wherein the clamping element is formed as a curved clamping piece arranged in a recess in the end portion.

5. The attachment device in accordance with claim 4, wherein one or more of the side edges of the recess forms a ledge arranged to receive a corresponding collar portion arranged on the clamping element.

6. The attachment device in accordance with claim 1, wherein the attachment portion is provided with an internal recess encircled by the locking portion and having an axial extent larger than the axial extent of the locking portion.

7. The attachment device in accordance with claim 6, wherein the at least one clamping element is a plurality of clamping elements separated by slits through the attachment portion.

8. The attachment device in accordance with claim 1, wherein the tubular body is a casing, a liner or a bottom-hole assembly.

9. The attachment device in accordance with claim 1, wherein the locking portion is formed as a threaded portion arranged to engage an internally threaded portion of the adapter sleeve.

10. The attachment device in accordance with claim 1, wherein the pipe stem or the supporting sleeve comprises one or more function elements taken from a group consisting of stabilizing elements, centralizing elements, sand screens and cable clamps.

11. The attachment device in accordance with claim 1, wherein the pipe stem or the supporting sleeve comprises one or more anchoring points for a function element.

12. The attachment device in accordance with claim 1 wherein the at least one clamping element further comprises a gripping face arranged to be pressed against the tubular body upon radial displacement of the at least one clamping element.

13. The attachment device in accordance with claim 12 wherein the at least one clamping element forms at least one clamping face comprising the gripping face.

14. The attachment device in accordance with claim 1, wherein the at least one clamping element is a plurality of clamping elements separated by slits through the attachment portion.

15. A pipe string comprising several tubular bodies, wherein one or more tubular bodies comprise at least one supporting sleeve fixed to said tubular body by an attachment device being in releasable engagement with a portion of said tubular body, wherein the attachment device is for a pipe stem and comprises: one or more radially projecting function elements made to be arranged on said tubular body, wherein an end portion of the pipe stem or an end portion of a supporting sleeve abutting the pipe stem, which is arranged to surround a portion of the tubular body, is provided with an attachment portion which includes at least one clamping element arranged for inward radial displacement by the abutment of an abutment surface of the attachment portion against a conical abutment portion on a surrounding adapter sleeve, wherein an external locking portion of the end portion is formed as several catches extending in the circumferential direction of a jacket surface of the attachment portion and being arranged to engage corresponding engagement elements projecting inwards on the adapter sleeve, the circumferential extent of the catches being defined by slits penetrating at least the locking portion and extending substantially in the axial direction of the attachment portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

(2) FIG. 1 shows a mandrel axially fixed with two sleeves according to the invention, the sleeves having been pulled slightly away from the end faces of the mandrel for the sake of exposure, and the mandrel being provided with stabilizers attached to an external jacket surface;

(3) FIG. 2 shows, in perspective, two sleeves according to the invention integrated in the mandrel;

(4) FIG. 3 shows, on a larger scale, an axial section through an attachment portion with an adapter sleeve formed as a nut screwed partially onto the attachment portion;

(5) FIG. 4a shows, on a larger scale, an axial section through an alternative embodiment of the attachment portion;

(6) FIG. 4b shows a radial section IV-IV according to FIG. 4a;

(7) FIG. 5 shows, on a larger scale, an axial section of a section of an alternative embodiment of the attachment portion and the nut, a locking portion in an end portion of the nut being engaged in a latch groove in the mandrel;

(8) FIG. 6 shows an axial section through an attachment portion and an adapter sleeve provided with a catch system, in which engagement elements projecting inwards on the adapter sleeve are being moved into engagement with corresponding catches on the attachment portions;

(9) FIG. 6a shows an enlarged section of the catch system; and

(10) FIG. 7 shows a view corresponding to FIG. 6, but where the engagements are fully engaged in the catches.

DETAILED DESCRIPTION OF THE DRAWINGS

(11) In the figures, the reference numeral 1 indicates a sleeve in the form of an elongated mandrel provided with several function elements 2, shown in FIGS. 1 and 2 as rib-shaped stabilizing elements projecting from a jacket surface 12 of the mandrel 1. The mandrel 1 is arranged to releasably surround a portion of a tubular body 3, shown schematically in FIGS. 1 and 2 as a casing. In FIG. 1, the mandrel 1 is fixed by means of two separate sleeves 1a, for example when it is desirable that the mandrel 1 with the function elements 2 should be rotatable on the tubular body 3, as an attachment sleeve 1a is positioned in an axially supporting manner against both end portions 11 of the mandrel 1, which, in this embodiment, have straight end faces 111. The sleeves 1a are attached in a rotationally rigid manner to the tubular body 3 no that the mandrel 1 may rotate freely. In FIG. 2, attachment devices for the sleeves 1a are integrated in both end portions 11 of the mandrel 1 so that the mandrel 1 is attached to the tubular body 3 in a rotationally rigid manner.

(12) In the following description, the attachment device is described in relation to the sleeve 1a, but is valid also when the sleeve 1a forms an elongated mandrel 1 provided with said attachment device(s).

(13) An end portion 11 of the sleeve 1a is provided with an attachment portion 13 which, in a first embodiment (see FIG. 3) includes a clamping portion 131 arranged to abut in a holding manner against the tubular body 3. The clamping portion 131 is formed from several lip-shaped clamping elements 1312 projecting in the axial direction from the sleeve 1a, the clamping elements 1312 being separated by slits 1311. The slits 1311 are shown here as straight-lined and parallel and are arranged in the axial direction of the sleeve 1a, but other designs are possible as well. The internal side faces of the clamping elements 1312 form clamping faces 1313 arranged to rest, in an active position, against the tubular body 3. The clamping faces 1313 are gently conical with an increasing diameter towards the free ends of the clamping elements 13, typically with a pitch angle in the range of 2-5. The pitch angle roughly corresponds to the pitch angle of the abutment surface 142 of an encircling adapter sleeve 14 (see below) to provide the desired contact between the clamping faces 1313 and the surrounded tubular body 3. In one embodiment (see FIGS. 6 and 7), a portion of the clamping faces 1313 constitutes a gripping face 1313, shown as toothed here, but other friction-enhancing designs may be used, for example serration.

(14) In a second embodiment (see FIGS. 4a and 4b), the attachment portion 13 is provided with several recesses 132, each accommodating a clamping element 1312 in the form of a curved clamping piece provided with a conical, outward, abutment surface 1315 and a cylindrical, inward, clamping face 1313. The clamping face 1313 is preferably rough, for example serrated, to exhibit sufficiently large friction against a surface. The recess 132 is provided with ledges 1321 arranged to receive corresponding collar portions 1314 having the effect of preventing the clamping element 1312 from falling out of the recess 132.

(15) In one embodiment, a locking portion 133 is arranged to engage in the adapter sleeve 14 in an axially fixing manner as the locking portion 133 is formed as an externally threaded portion extending along a portion of the jacket surface 12 from the bottom of the slits 1311.

(16) In this embodiment, the adapter sleeve 14 is formed as a nut provided with an internally threaded portion 141 complementary to the externally threaded portion 133 of the sleeve 1a. In the further description, the term nut is partly used when the adapter sleeve 14 is provided with an internally threaded portion 141.

(17) In another embodiment, the axial fixing of the adapter sleeve 14 on the attachment portion 13 is provided by a catch system, the locking portion 133 including several external catches 134, each extending in the circumferential direction of the jacket surface 12 across a region of the attachment portion 13 which is split by slits, shown in FIGS. 6 and 7 as the slits 1311 defining the clamping elements 1312. Internally to the locking portion 133, the attachment portion 13 exhibits a recess 135 which, with its diameter larger than that of the adjacent portions of the centre bore of the sleeve 1a, extends beyond the axial extent of the locking portion 133. The slitting of the attachment portion 13 together with the corresponding internal recess 135 allows the locking portion 133 to be pressed inwards when the adapter sleeve 14 (see FIG. 7), which, in this embodiment, is provided with engagement elements 141 projecting inwards, is moved in over the locking portion 133. In the embodiment shown, the catches 134 are provided with a first, conical side face 134a facing the end of the clamping portion 131, for example with a pitch in the range of 20-35, about 30 shown here. An opposite, second side face 134b forms an abutment surface, shown here as a shoulder standing perpendicularly to the centre axis of the clamping portion 131. Correspondingly, the engagement elements 141 of the adapter sleeve 14 have a cross section complementary to the cross section of the catches 134 so that an engagement element 141 will slide with a conical, inward side face 141a on the conical outward side face 134a of the catch 134 as the locking portion 133 is compressed in the radial direction until the engagement element 141 engages behind said catch 134 by its axially supporting abutment against the abutment surface 134b of the catch 134. In this embodiment, the engagement elements 141 are typically similarly shaped and arranged with regular axial spacing. Here, the locking portion is shown with several catches 134 spaced apart axially, the axial spacing pitch corresponding to the spacing of the engagement elements 141 of the adapter sleeve 14.

(18) Reference is now made to FIGS. 3 and 4a in particular. Between the engagement elements 141 and a first end 14a of the adapter sleeve 14, a conical abutment portion 142 extends with a diameter decreasing in the direction away from the engagement elements 141. The pitch angle of the conical abutment portion 142 is preferably equal to the pitch angle of the clamping faces 1313 of the clamping element 1312 or the abutment surface 1315 of the clamping elements 1312, in order thereby to provide good contact between the clamping faces 1313 of the lips 1312 or clamping pieces 1312 and the surrounded tubular body 3 when the clamping elements 1312, 1312 are in their active positions.

(19) In the embodiment as a nut, the adapter sleeve 14 is provided with several grip portions 144 (see FIGS. 3 and 4a), shown here as cut-outs extending through the conical portion of wall of the adapter sleeve 14. The grip portions 144 are arranged to be releasably engaged by a tool (not shown) for rotating the nut 14.

(20) Reference is now made to FIG. 5, in which an embodiment with several parallel latch grooves 134 arranged adjacent to the externally threaded portion 133 is shown. A complementary engagement element 141 projects inwards like a ridge from the internal wall surface of the nut 14, with a distance to the internally threaded portion 141. The engagement element 141 is arranged to be yielding so that by the axial displacement of the nut 14 on the externally threaded portion 133, it may climb on the side edges of the latch grooves 134. The engagement portion 141 may, for example, be formed as a yielding one by the use of a small material thickness in the adjacent portion of the wall of the nut 14, possibly by the engagement portion 141 and the adjacent portion of the wall of the nut 14 being split with slits arranged axially (not shown).

(21) Alternatively, the nut 14 may be provided with a catch system, as described above and shown in the FIGS. 6 and 7, to prevent the nut 14 from unscrewing.

(22) It is obvious to provide both end portions 11 of a sleeve 1a formed as a mandrel 1a with attachment portions 13 of the kind as described above. It is also obvious to choose a thread direction that will prevent the nut 14 from unscrewing as the tubular body 3 is rotated in its normal direction of rotation.

(23) When a pipe string that is being constructed from said tubular bodies 3 is to be provided with function elements 2, for example a new casing is to be centred in a previously installed casing in such a way that sufficient clearance is ensured between the casings for the satisfactory introduction of cement, a mandrel 1 with function elements 2 and adapter sleeve/sleeves 14 is slipped over the relevant tubular body 3 and fixed in the desired position by the adapter sleeve/sleeves 14 being clamped in such a way that the clamping faces 1313 and possible gripping faces 1313 of the clamping elements 1312 are pressed against the jacket surface of the tubular body 3. By the use of attachment sleeves 1a according to the invention, the mandrel 1, attachment sleeve/sleeves 1a and adapter sleeve/sleeves 14 are slipped over the tubular body 3 in the desired order and orientation. The attachment sleeve/sleeves 1a is/are attached in a manner corresponding to that described above. Correspondingly, the sleeve 1a is used as an attachment for one or more function elements 2 by the function element 2 being attached to a suitable anchoring point 136 on the sleeve, shown in FIG. 6 as a threaded recess, and shown in FIG. 7 as a projecting threaded pin.