NO341125B1

NO341125B1 - Wellbore cleaning tool and method for assembling the cleaning tool

Info

Publication number: NO341125B1
Application number: NO20151762A
Authority: NO
Inventors: Atle Løland; Trond Skjeie; Thomas Bergesen
Original assignee: Archer Oiltools As
Priority date: 2015-12-21
Filing date: 2015-12-21
Publication date: 2017-08-28
Also published as: NO20151762A1

Description

WELLBORE CLEANING TOOL

Field of the invention

[0001] The present invention relates to the technical field of downhole cleaning tools for wellbores. More specifically it relates to the cleaning of interior tubular members of the wellbore, such as liner, casing and tubing.

Background art

[0002] A number of different solutions for wellbore cleaning tools have been disclosed. Some of the tools are rotating, meaning that the scrapers or brushes rotate with the tool string, and relative the tubular member. If the tool string is connected to a drill string, such rotating tools may result in damages to the interior of the tubular members they are cleaning, and to the tools themselves. In many situations it is therefore desirable to have non-rotating tools, meaning that the scrapers or brushes do not rotate relative the tubular member, but relative the drill string.

[0003] Patent application GB2334541 A discloses a well cleaning tool with rows of different cleaning members, such as scrapers and brushes, as well as stabilizers at the end of the tool that can rotate freely relative the supporting structure, i.e. mandrel. However, this and similar tools are difficult to manufacture, and the cleaning members cannot be easily replaced.

[0004] US patent application US2011265988 Al discloses a wellbore cleaning device håving a unita ry tool mandrel surrounded by a retaining sleeve that is rotatable with respect to the mandrel. The retaining sleeve is a split sleeve made up two sleeve halves with a longitudinal split. A locking ring is used to secure the two halves together at the middle, while the other ends of the sleeve halves are secured under stabilizers that are threaded onto the two sleeve halves. The stabilizers therefore rotate with the sleeve on the tool string.

[0005] International patent application WO2014003576 A2 also shows a wellbore cleaning device with a unitar/mandrel surrounded by a split rotating sleeve. A stabilizer is also here attached to the end of the sleeve and partly covering the sleeve. A locking damp at the far end is used to secure the sleeve from longitudinal movement.

[0006] GB 2430687 A describes a holding device for preventing longitudinal movement of a sleeve(s) on a substantially cylindrical body of a downhole tool. The holding device comprises a split ring, a retaining ring and a circlip.

[0007] International patent publication WO2009009456 (Al) describes an apparatus for cleaning the inner wall of wellbore tubulars. An elongated, tubular central mandrel has threaded connections on either end for makeup into a tubular string. The mandrel has recesses on its outer circumference into which split rings are mounted Various service elements are then attachable to the central mandrel, by sliding them over the mandrel and holding them in place with stabilizer elements which connect to the split rings

[0008] Some of the prior art described above have a complex radial structure, making it difficult to obtain the necessary material thickness of the tool parts for operating in harsh wellbore environments. In addition, the stabilizers and the tool sleeves have a common rotation, which may under certain conditions reduce the cleaning effect.

Short summary of the invention

[0009] A main object of the present invention is to disclose a wellbore cleaning tool that solves the problems of the prior art cleaning tools.

[0010] The current invention is a wellbore cleaning tool (1) comprising

- an elongate mandrel (5) with a first section (2), a second section (4) and an intermediate section (3) between said first and second sections (2,4), wherein an outer diameter of the intermediate section (3) is smaller than outer diameters of the first and second sections (2,4), - a longitudinally split cylindrical tool sleeve (10) comprising one or more replaceable cleaning members (300) and first and second sleeve members (10a, 10b), arranged about said intermediate section (3), - a longitudinally split locking sub (21) comprising first and second locking sub members (21a, 21b), arranged about said intermediate section (3), wherein each of said first and second sleeve members (10a, 10b), comprises first interlocking means (101a, 101b), and each of said first and second locking sub members (21a, 21b)

comprises second interlocking means (201a, 201b), wherein said first interlocking means (101a) of both said first and second sleeve member (10a, 10b) interlock with said second interlocking means (201a, 201b) of both said first and second locking sub members (21a, 21b), so that said first and second sleeve members (10a, 10b) are locked relative each

other in a radial direction,

- a longitudinally split tool bearing (22) arranged between said intermediate section (3) and said locking sub (21), allowing said locking sub (21) and said cylindrical tool sleeve (10) to rotate relative said mandrel (5). [0011] In an embodimentthe invention is also a method for assembling a wellbore cleaning tool (1) comprising the steps of; - providing an elongate mandrel (5) with a first section (2), a second section (4) and an intermediate section (3) between said first and second sections (2,4), wherein an outer diameter of the intermediate section (3) is smaller than outer diameters of the first and second sections (2,4), - arranging a longitudinally split cylindrical tool sleeve (10) comprising first and second sleeve members (10a, 10b), about said intermediate section (3), wherein each of said first and second sleeve members (10a, 10b), comprises first interlocking means (101a, 101b), - arranging first and second locking sub members (21a, 21b) about said intermediate section (3) to form a longitudinally split locking sub (21) wherein each of said first and second locking sub members (21a, 21b) comprises second interlocking means (201a, 201b), - arranging said first interlocking means (101a, 101b) of both said first and second sleeve member (10a, 10b) to interlock with said second interlocking means (201a, 201b) of both said first and second locking sub members (21a, 21b), so that said first and second sleeve members (10a, 10b) are locked relative each other in a radial direction, - arranging first and second tool bearing members (22a, 22b) about said intermediate section and between said intermediate section (3) and said locking sub (21), to form a longitudinally split tool bearing (22) allowing said locking sub (21) and said cylindrical tool sleeve (10) to rotate relative said mandrel (5).

[0012] The prior art tools listed above are all successively built up around a mandrel from the center and radially outwards, i.e. in a layered approach. This requires unnecessary fastening means, such as screws, and a radial complexity due to the layered structure. The current invention reduces this radial complexity since the tool can be assembled in the longitudinal direction. I.e, parts are added from the middle, starting with the split tool sleeve towards the end. This is possible because all essential parts are split, and designed for mutual locking.

[0013] The wellbore cleaning tool and the methodforassembling the tool, has the advantage that the split tool sleeve is laterally fixed to the mandrel without the use of any additional members covering the sleeve, such as e.g. external locking rings or stabilizers threaded onto the sleeve from the top or bottom. Thus, when dimensioning the mandrel and the sleeve, weak points can be avoided since the cross section can be reserved for the sleeve itself.

[0014] In an embodiment the locking element (23) is a stabilizer bearing and a stabilizer (25) is arranged about said stabilizer bearing.

[0015] This has the advantage that the tool in this embodiment has a tool sleeve that is independent of the stabilizer since the tool sleeve and the stabilizer are supported by independent bearings. Thus, the tool sleeve and the stabilizer will both rotate freely with regard to the mandrel and with regard to each other.

[0016] In addition, the tool has several other advantages, i.e. that the mandrel is in one single piece, which is a requirement in most applications, worn part can be easily replaced, and cleaning members attached to the tool can be easily replaced when worn, or with other types of cleaning members when required.

Figure captions

[0017] The attached figures illustrate some embodiments of the claimed invention.

[0018] Fig. 1 illustrates in a side view an embodiment of the cleaning tool according to the invention.

[0019] Fig. 2 shows a sectional view of the same embodiment as in Fig. 1 of the tool.

[0020] Fig. 3a and 3b are exploded views of the tool illustrated in Fig. 1 and 2.

[0021] Fig. 4 is a partial view of Fig. 2, illustrating the main parts making up an embodiment of the invention in more detail.

[0022] Fig. 5 and 6 are a partial views of an embodiment of the invention illustrating steps of the assembly.

[0023] Fig. 7 is a portion of the exploded view in Fig. 3a, illustrating in more detail some aspects of the cleaning tool. Note that the intermediate section (3) is only partly shown.

Embodiments of the invention

[0024] The invention will in the following be described and embodiments of the invention will be explained with reference to the accompanying drawings.

[0025] Fig. 1 and Fig. 2 illustrates the same embodiment of the cleaning tool according to the invention. Fig. 1 is a side view of an embodiment of the assembled cleaning tool, while Fig. 2 is a sectional view of the same tool.

[0026] The cleaning tool (1) has a single-piece mandrel (5) extending from top to bottom of the tool. Preferably the mandrel (5) has screw joints for being connected with corresponding joints of the drill string.

[0027] As can be seen from the drawings, the mandrel (5) has a specific shape to accommodate the other parts of the tool. The top and bottom ends have corresponding first and second sections (2, 4) with larger outer diameters than the outer diameter of the intermediate section (3). This can also be seen in the rest of the figures 3, 4 and 5.

[0028] A longitudinally split cylindrical tool sleeve (10) is arranged about the middle portion of the intermediate section (3), while stabilizers (25, 26) are arranged about the end portions of the intermediate section (3). Thus, in the final assembled tool, the stabilizers and their bearings lock the tool sleeve (10) in the longitudinal direction, while the raised edges of the first and second sections (2, 4) prevent the stabilizers from extending outwardly at each end. However, as will become apparent later, the tool sleeve (10) and the stabilizers (25, 26) can rotate independently on the mandrel (5).

[0029] Fig. 3a and 3b illustrates in an exploded view the main members making up the cleaning

tool (1) according to this embodiment of the invention.

[0030] Here the first and second sleeve members (10a, 10b) of the longitudinally split cylindrical tool sleeve (10) are illustrated, and as can be seen, in an end, the first and second sleeve members (10a, 10b) have a wedge shaped cut or insert (101a, 101b).

[0031] Further, the next element is a longitudinally split locking sub (21) comprising first and second locking sub members (21a, 21b), arranged about said intermediate section (3), where each of said first and second locking sub members (21a, 21b) comprises second interlocking means (201a, 201b). Each of the second interlocking means (201a, 201b) has the shape of a half dovetail, and when the first and second locking sub members (21a, 21b) are assembled around the mandrel (5), a dovetail will be formed from the two half dovetails as shown in the figure. The dovetail can then be pushed into the corresponding wedge shaped cut or insert (101a, 101b).

[0032] In this embodiment the two dovetails on the locking sub (21) are formed from two pair of dovetail halves on the two locking sub members (21a, 21b).

[0033] The dovetail is also wedge shaped to fit into the wedge shaped cut or insert (101a, 101b), where the outer diameter segment of the dovetail is larger than the inner diameter segment. This ensures that once the dovetail is in place in the cut, the first and second sleeve members (10a, 10b) are locked to each other, through the first and second locking sub members (21a, 21b), in the radial direction.

[0034] In this embodiment the two locking sub members (21a, 21b) comprises a support surface (210a, 210b) that extends under the first and second sleeve members (10a, 10b). Thus, the dovetails of the locking sub (21) prevent outward radial movement, while the support surface of the same locking sub (21) prevents inward radial movement of the first and second sleeve members (10a, 10b).

[0035] The longitudinal split of the cylindrical tool sleeve (10) is rotated with respect to the split of the locking sub (21). In this specific embodiment, the rotation is 90 degrees, but other rotations may also be used.

[0036] Further, the invention according to this embodiment comprises a longitudinally split tool bearing (22) arranged between said intermediate section (3) of said mandrel (5) and said locking sub (21). When the tool bearing (22) is arranged in its position, the locking sub (21) and the tool sleeve (10) can rotate relative the mandrel (5) on the tool bearing (22) .

[0037] A longitudinally split locking element (23) is used to prevent the other members described above from moving in the longitudinal direction.

[0038] The locking element (23) is arranged between said tool bearing (22) and said first section (2) on the end of the intermediate section (3) of the mandrel (5). The locking element (23) is configured to fit into the remaining part of the intermediate

section (3) not occupied by other members.

[0039] For most applications, it is desirable to use stabilizers for aligning the tool inside the wellbore. In this embodiment, the locking element (23) is therefore a split stabilizer bearing, and a stabilizer (25) is arranged over the split stabilizer bearing . The stabilizer is not split. It has an inner diameter larger than the outer diameter of the first section (2) of the mandrel (5), and can slide over this part of the mandrel.

[0040] To fix the stabilizer in the longitudinal direction over the split stabilizer bearing, the tool in this embodiment comprises a longitudinally split stabilizer sub (24). The stabilizer sub (24) and the split stabilizer bearing each comprises corresponding locking means to prevent the longitudinal movement of the stabilizer sub (24) relative the split stabilizer bearing and the mandrel (5).

[0041] The stabilizer sub (24) and the stabilizer (25) have respective external and internal threads, so that the stabilizer can be screwed onto the stabilizer sub (24) when entered from the end of the tool (1).

[0042] After the tool has been assembled according to the description above, it can be connected to a e.g. a drill pipe, and should be ready for use.

[0043] Cleaning members can be added before assembly of the tool or after.

[0044] In an embodiment a locking ring is used instead of the stabilizers. The locking ring is entered onto the split locking element (23) from the end of the tool, and fixed to the split locking element (23) by e.g. threads or other fastening means such as set screws. Alternatively, the first and second locking element members (23a, 23b) of the longitudinally split locking element (23) may be interconnected by fastening means, such as screws, to ensure that they do not fall of during operation.

[0045] Fastening means can also be used to secure the longitudinally split elements as illustrated in the drawings for e.g. the first and second sleeve members (10a, 10b), first and second locking sub members (21a, 21b), first and second tool bearing members (22a, 22b), first and second locking element members (23a, 23b) and first and second stabilizer sub members (24a, 24b). This can be useful to e.g. ease tool assembly.

[0046] The inner part of the bearing (22) should be fixed with respect to the mandrel (5). In this embodiment, the tool bearing (22) is rotationally fixed to the stabilizer bearing (23) and the stabilizer bearing (23) is locked to the first section (2) of the mandrel (5). Thus, inserts or cuts in the mandrel for each element is not needed.

[0047] As illustrated in Fig. 7, the tool bearing (22) and the stabilizer bearing (23) comprises corresponding rotational locking means (222a, 222b) and (232c, 232d)

(position is indicated in the figure, but the latter locking means cannot be seen directly)

for locking said tool bearing (22) to said stabilizer bearing (23) in a radial direction.

[0048] Further the stabilizer bearing (23) and the first section (2) comprises corresponding rotational locking means (232a, 232b) and (532c, 532d) (position is indicated in figure 6, but the latter locking means cannot be seen directly) for locking said stabilizer bearing (22) to said first section (2). The various corresponding rotational locking means can be implemented as e.g. tongue and groove.

[0049] In the embodiment described above, the sleeve members (10a, 10b) are semicircular. This is also the case for the other longitudinal split elemenfs. However, in other embodiments the split elements may have other shapes. E.g. elements with three splits could also be used.

[0050] In this embodiment the second end of the tool is implemented in the same way as described above for the first end. However, the second end may also have a simpler implementation, since sleeve members may be supported by an existing bearing that is not necessarily split, and radially and longitudinally fixed by a fixed locking element or the stabilizer (26).

[0051] The said first and second sleeve members (10a, 10b), comprises in an embodiment one or more cleaning member retainers (200), each arranged for replaceably holding a replaceable cleaning element (300) as illustrated in Fig. 2. The cleaning elements (300) may be brushes, scrapers, cutters or similar used for cleaning the interior of a wellbore.

[0052] In an embodiment the cleaning member retainers (200) are arranged as protruding flanges (201, 202) on the first and second sleeve members (10a, 10b), such that the cleaning elements (300) can be inserted into the cleaning member retainers

(200) and prevented from radial outward movement by the protruding flanges (201, 202). In this embodiment one or more springs (205) are inserted between the sleeve member (10a, 10b) and the cleaning elements (300), such that the cleaning elements can adapt to the irregularities inside the wellbore to be cleaned.

[0053] Stopper elements, not shown, may be inserted between the cleaning members

(300) to prevent them from rotating out of their position.

Claims

1. A wellbore cleaning tool (1) comprising - an elongate mandrel (5) with a first section (2), a second section (4) and an intermediate section (3) between said first and second sections (2,4), wherein an outer diameter of the intermediate section (3) is smaller than outer diameters of the first and second sections (2,4), - a longitudinally split cylindrical tool sleeve (10) comprising one or more replaceable cleaning members (300) and first and second sleeve members (10a, 10b), arranged about said intermediate section (3)characterized in thatsaid wellbore cleaning tool comprises; - a longitudinally split locking sub (21) comprising first and second locking sub members (21a, 21b), arranged about said intermediate section (3), wherein each of said first and second sleeve members (10a, 10b), comprises first interlocking means (101a, 101b), and each of said first and second locking sub members (21a, 21b) comprises second interlocking means (201a, 201b), wherein said first interlocking means (101a, 101b) of both said first and second sleeve member (10a, 10b) interlock with said second interlocking means (201a, 201b) of both said first and second locking sub members (21a, 21b), so that said first and second sleeve members (10a, 10b) are locked relative each other in a radial direction, - a longitudinally split tool bearing (22) arranged between said intermediate section (3) and said locking sub (21), allowing said locking sub (21) and said cylindrical tool sleeve (10) to rotate relative said mandrel (5), and - a longitudinally split locking element (23) arranged between said tool bearing (22) and said first section (2), such that said first and second sleeve members (10a, 10b) are restricted from moving in a longitudinal direction towards the first section (2).

2. A wellbore cleaning tool (1) according to claim 1, comprising a stabilizer (25) arranged about said locking element (23).

3. A wellbore cleaning tool (1) according to claim 2, wherein said locking element (23) is a stabilizer bearing, arranged to allow said stabilizer (25) rotate on said stabilizer bearing.

4. A wellbore cleaning tool (1) according to claim 3, comprising a longitudinally split stabilizer sub (24) arranged between said locking element (23) and said stabilizer (25), wherein said stabilizer (25) is fixed to said stabilizer sub (24).

5. A wellbore cleaning tool (1) according to claim 3, wherein said stabilizer sub (24) comprises an external threaded surface (241), and said stabilizer (25) comprises a corresponding internal threaded surface (251), such that said stabilizer can be screwed onto said stabilizer sub (24).

6. A wellbore cleaning tool (1) according to any of the claims above, wherein said tool bearing (22) comprises rotational locking means (222a,222b) for locking said tool bearing (22) to said locking element (23).

7. A wellbore cleaning tool (1) according to any of the claims above, wherein said first interlocking means (101a, 101b) are wedge shaped cuts, and said second interlocking means (201a, 201b) are split dovetails, and wherein pairs of said split dovetails are arranged in a respective split wedge shaped cut.

8. A wellbore cleaning tool (1) according to any of the claims above, wherein any of the first and second sleeve members (10a, 10b), are semicircular.

9. A wellbore cleaning tool (1) according to any of the claims above, wherein said first and second locking sub members (21a, 21b) comprises a support surface (210a, 210b) arranged under said first and second sleeve members (10a, 10b).

10. A method for assembling a wellbore cleaning tool (1) comprising the steps of; - providing an elongate mandrel (5) with a first section (2), a second section (4) and an intermediate section (3) between said first and second sections (2,4), wherein an outer diameter of the intermediate section (3) is smaller than outer diameters of the first and second sections (2,4), - arranging a longitudinally split cylindrical tool sleeve (10) comprising first and second sleeve members (10a, 10b), about said intermediate section (3), wherein each of said first and second sleeve members (10a, 10b), comprises first interlocking means (101a, 101b) said methodcharacterized in; - arranging first and second locking sub members (21a, 21b) about said intermediate section (3) to form a longitudinally split locking sub (21) wherein each of said first and second locking sub members (21a, 21b) comprises second interlocking means (201a, 201b), - arranging said first interlocking means (101a, 101b) of both said first and second sleeve member (10a, 10b) to interlock with said second interlocking means (201a, 201b) of both said first and second locking sub members (21a, 21b), so that said first and second sleeve members (10a, 10b) are locked relative each other in a radial direction, - arranging first and second tool bearing members (22a, 22b) about said intermediate section (3) and between said intermediate section (3) and said locking sub (21), to form a longitudinally split tool bearing (22) allowing said locking sub (21) and said cylindrical tool sleeve (10) to rotate relative said mandrel (5), and - arranging first and second locking element members (23a, 23b) between said tool bearing (22) and said first section (2), to form a longitudinally split locking element (23) such that said first and second sleeve members (10a, 10b) are restricted from moving in a longitudinal direction towards the first section (2).

11. The method according to claim 10, comprising the step of; - screwing a stabilizer (25) onto said locking element (23).

12. The method according to claim 11, wherein said locking element (23) is a stabilizer bearing, arranged to allow said stabilizer (25) rotate on said stabilizer bearing.

13. The method according to claim 12, comprising the step of; - arranging first and second stabilizer sub members (24a, 24b) onto said stabilizer bearing to form a longitudinally split stabilizer sub (24) before screwing said stabilizer (25) onto said stabilizer sub (24).

14. The method according to claim 13, wherein said stabilizer sub (24) comprises an external threaded surface (241), and said stabilizer (25) comprises a corresponding internal threaded surface (251), wherein said method comprises the step of; - screwing said stabilizer by rotation onto said stabilizer sub (24).

15. The method according to any of the claims above, wherein said first interlocking means (101a, 101b) are wedge shaped cuts, and said second interlocking means (201a, 201b) are split dovetails, wherein said method comprises the step of; - arranging pairs of said split dovetails in respective split wedge shaped cuts.