GB2360537A

GB2360537A - Roller reaming tool with thrust bearing

Info

Publication number: GB2360537A
Application number: GB0107232A
Authority: GB
Inventors: Graham Edgley; Niels Christian Olaf Friis
Original assignee: DESIGN ENGINEERING Ltd
Current assignee: DESIGN ENGINEERING Ltd
Priority date: 2000-03-22
Filing date: 2001-03-22
Publication date: 2001-09-26
Anticipated expiration: 2021-03-22
Also published as: GB0107232D0; GB2360537B; GB0006757D0

Abstract

A roller reaming tool for mounting on a tool string comprises an elongate body 13 having a plurality of recesses positioned circumferentially around the body 13, each recess housing a roller reamer unit 1. The roller reamer units each comprise a reaming roller 2 rotatably mounted on a shaft 3, the latter being held stationary by retaining blocks 5 and 6. Each reaming roller 2 co-operates with a thrust bearing 11 in a shoulder of a respective upper retaining block 5.

Description

2360537 1 1 Roller Reamer with Thrust Bearing 2 3 The present invention

relates to an improved design for a 4 roller reamer for use with earth boring tools for 5 creating well bores. 6 7 Well drilling operations are carried out by advancing 8 extendible lengths of drill string, with a drill bit at 9 the lower end, into the earth. It has become common 10 practice to include one or more roller reamers on the 11 drill string, typically behind the drill bit, to enlarge 12 and even the surface of the newly created bore, as it is 13 often the case that a true hole is not created by the 14 action of the drill bit alone. The inclusion of a roller 15 reamer on the drill string also centralises the drilling 16 apparatus within the bore. 17 18 In general, roller reamer tools have a plurality of 19 recesses circumferentially positioned around the body of 20 the tool, which are adapted to receive individual roller 21 reamer units. These are comprised of a roller reamer 22 cutter or cutters which are typically mounted on, and 23 rotate relative to a fixedly held shaft or spindle. The 2

1 shaft or spindle is usually held in a stationary 2 position by retaining blocks. Each unit is fitted into a 3 recess on the roller reamer tool body. In the present 4 specification references to a roller reamer unit are 5 intended to encompass a roller reamer cutter or cutters, 6 a shaft around which the roller reamer cutter rotates and 7 retaining blocks which hold the shaft stationary, and 8 allow mounting of the roller reaming cutter onto the body 9 of the roller reamer tool. 10 11 It will be appreciated by those skilled in. the art that 12 roller reamers are subject to hostile conditions during 13 use and that roller reamer parts generally have a very 14 limited life span. In particular, the roller reamer 15 cutters, which closely contact the wall of the well bore, 16 are subject to considerable resistance and torque as the 17 drill string is forced downward through the bore. 18 19 In conventional roller reamer tools, it is known to the 20 art to incorporate a number of ball bearings between the 21 roller reamer cutter and shaft which allow the roller 22 reamer cutter to rotate relative to the shaft. In 23 addition the ball bearings withstand the radial pressure 24 placed on the reamer cutter by contact with the well bore 25 walls, which otherwise would cause excess wear on the 26 outer facing surface of the reamer shaft. The inclusion 27 of roller bearings between the shaft and cutter is taught 28 in US Patent No 3413045, US Patent No 2190350 and US 29 Patent No 5381868. In a common embodiment the roller 30 reamer cutter has a small passageway which extends 31 radially through the roller reamer cutter, through which 32 the ball bearings can be dropped at the time of assembly 33 into receiving means between the shaft and roller reamer

3 1 cutter. These allow the reamer to rotate freely relative 2 to the shaft. 3 4 The inclusion of ball bearings between the shaft and 5 cutter minimise wear of the outer facing surface of the 6 shaft. However as the tool is advanced downhole on a 7 work string, the roller reamer cutters are subject to 8 force acting in an upward direction as they contact the 9 wall of the well bore. Accordingly, considerable wear 10 can also occur between the roller reamer cutter and upper 11 retaining block, as thrust loads are afforded to this 12 area of the roller reamer unit when the tool is forced 13 down through the well bore. 14 15 A further disadvantage of conventional ball bearings lies 16 in their assembly. Typically, a number of individual 17 ball bearings are used in the roller reamer unit as a 18 means to withstand thrust, and each has to be 19 individually assembled and greased before use. 20 21 It would therefore be a distinct advantage to provide a 22 roller reamer tool which has thrust bearing means 23 between the roller reamer cutter and upper retaining 24 block, which holds the rotating roller reamer cutter 25 against thrust which is afforded to this area as the tool 26 is advanced downhole, but which does not hinder rotation 27 of the roller reamer cutter. 28 29 It is an object of at least one embodiment of the present 30 invention to provide a roller reamer unit, wherein the 31 reaming cutters of said roller reamer unit have means for 32 resisting axial torque and thrust as a drill string is 33 run into a bore.

4 2 It is a further object of at least one embodiment of the 3 present invention to provide a bearing which permits 4 rotation of a roller reamer cutter and which is simple to 5 install and can withstand high levels of torque. 6 7 It is a yet further object of at least one embodiment of 8 the present invention to provide a premanufactured 9 bearing means for use in a roller reamer unit. 10 11 According to the present invention there is provided a 12 roller reamer tool for mounting on a work string 13 comprising an elongate body having a plurality of 14 recesses positioned circumferentially around said body, 15 each recess being adapted to house a roller reamer unit, 16 wherein said roller reamer unit is comprised of a shaft 17 which is held stationary by a first and second retaining 18 means, characterised in that said upper retaining means 19 has a shoulder with thrust bearing means, and wherein the 20 roller reamer unit further comprises a reaming member 21 which is rotatably mounted on the shaft and co-operates 22 with the thrust bearing means in the shoulder of the 23 upper retaining means. 24 25 Preferably the reaming member is a roller reamer. 26 27 Preferably the upper and lower retaining means are 28 bearing blocks. 29 30 Preferably said upper and lower bearing blocks fit in 31 corresponding pockets in a recess of the roller reamer 32 tool. 33 1 Preferably the shaft has a longitudinal length which is 2 greater than the longitudinal length of the roller 3 reamer. 4 5 Preferably the shaft is inserted into a corresponding 6 opening in the upper and lower bearing block. 7 8 Preferably the roller reamer cutter has a first tapered 9 end which fits within the shoulder of the upper bearing 10 block and cooperates with the thrust bearing means. 11 12 Preferably the thrust bearing means is a premanufactured 13 bearing which can be readily incorporated into the 14 shoulder of the upper retaining block at the time of 15 assembly of the apparatus. 16 17 Preferably the thrust bearing means is a ball bearing 18 racer. 19 20 Preferably the shaft has a longitudinally extending bore 21 to allow lubrication of the roller reamer unit. 22 23 Most preferably said longitudinally extending bore 24 communicates with at least one radial outlet. 25 26 Preferably said longitudinally extending bore has 27 pressure creating means for circulating a fluid through 28 the bore. 29 30 Most preferably said pressure creating means is a piston. 31 32 Preferably the roller reamer tool has connection means 33 for mounting the roller reamer tool on a work string.

6 2 Most preferably said connection means are threaded end 3 connections. 4 5 Preferably the roller reamer cutter is made of a hard 6 wearing and resistant material such as tungsten carbide 7 or polycrystalline diamond, although any other suitable 8 material may be used. 9 10 An example embodiment of the invention will now be 11 illustrated with reference to the following Figures in 12 which: 13 14 Figure 1 illustrates an individual roller reamer unit 15 shown in longitudinal cross section in accordance with 16 the present invention, and; 17 18 Figure 2 is an elevated view of a roller reamer tool with 19 mounted roller reamer units, and; 20 21 Figure 3 illustrates a roller reamer tool with a mounted 22 roller reamer unit shown in longitudinal cross section. 23 24 Referring to Figure 1 a roller reamer unit is shown in 25 longitudinal cross section at 1, comprising a roller 26 reamer cutter 2 which is mounted on a shaft 3. The shaft 27 3 has a greater longitudinal length than the roller 28 reamer cutter 2 and fits into corresponding openings 4 29 within an upper 5 and lower 6 retaining block. The 30 roller reamer cutter 2 rotates relative to the shaft 3, 31 which is held stationary by the upper 5 and lower 6 32 retaining block. 33 7 1 The shaft 3 has an internal bore 7 which extends along 2 the axis of the shaft 3. The internal bore 7 carries 3 drilling fluid which enters the shaft 3 via radial ports 4 8 which extend externally from the shaft 3. A moveable 5 pressure balancing piston 9 is located internally within 6 the bore 7 which forces fluid to circulate and lubricate 7 the bore 7 therethrough. 8 9 The upper block 5 has a shoulder 10 with a thrust bearing 10 11. The reamer cutter 2 is tapered at its upper end 12 11 such that it fits within the shoulder 10 of the upper 12 block 5 and contacts with the thrust bearing 11. The 13 thrust bearing 11 is essentially a ball bearing racer 14 which sits in the shoulder 10 of the upper block 5 and 15 allows one or more ball bearings to race' around the 16 outer circumference of the shaft 3 thereby allowing the 17 roller reamer cutter 2 to rotate with the ball bearing, 18 relative to the shaft 3 and the upper 5 and lower 6 19 retaining blocks. 20 21 Figures 2 and 3 illustrate the roller reamer unit 1 in 22 place in a roller reamer tool. The body of the roller 23 reamer tool 13 in Figure 2, has three recesses 14, which 24 are spaced equally around the circumference of the body 25 of the tool 13. However it will be appreciated that the 26 number of recesses 14 in the body 13 of the tool is not 27 limited to this number. The recesses 14 are sized to 28 receive an individual roller reamer unit 1 respectively, 29 and have an upper and lower block pocket into which the 30 upper and lower block 5 and 6 of the roller reamer unit 31 of Figure 1 can be inserted. On assembly of the roller 32 reamer unit 1, the shaft 3 is inserted into the 33 corresponding openings 4 of the upper 5 and lower 8 1 retaining block 6. As the shaft 3 has a greater 2 longitudinal length than the roller reamer cutter 2, the 3 roller reamer cutter 2, when assembled, sits between the 4 shoulder 10 of the upper block 5, and the lower block 6, 5 and rotates around the shaft 3. The shaft 3 is 6 preferably welded at one of either the upper 5 or lower 6 7 retaining block openings 4, such that the shaft 3, upper 8 5 and lower 6 retaining blocks and the reamer cutter 2 9 which is rotatably mounted on the shaft 3 can be inserted 10 into the recess 14 of the roller reamer tool 1 as a 11 single unit. The upper 5 and lower 6 retaining blocks 12 make an interference fit into corresponding upper and 13 lower retaining block pockets within the recess 14 of the 14 roller reamer tool body 13. The blocks 5 and 6 can then 15 be fixedly secured to the recess 14 in the body of the 16 roller reamer tool 1 by grub screws or the like. The 17 assembled tool can be seen from above in Figure 2 with 18 three roller reamer units 1, comprising a roller reamer 19 cutter 2, rotatably mounted on a shaft 3, with an 20 internal bore 7. The shaft 3 is held stationary by an 21 upper 6 and lower 5 retaining block which fit into the 22 recess 14 and are secured by grub screws 15. It is 23 recognised in the present invention that the blocks may 24 be of any shape. The upper retaining block 6 has a 25 thrust bearing 11 which sits in a shoulder of the 26 retaining block 6 into which a tapered end of roller 27 reamer cutter 12 is sized to fit. 28 29 The advantage of the present invention lies in the use of 30 thrust bearings 11 between the tapered upper end 12 of 31 the roller reamer cutter 2 and the upper retaining block 32 5, which are premanufactured and can be readily 33 incorporated into the tool 13. It will be appreciated to 9 1 those skilled in the art, that when the tool 1 is in 2 position on a work string, and is forcibly, rotated or 3 reciprocated into the ground, the roller reamer cutter 2 4 will be forcefully thrusted upwards against the upper 5 retaining block 5 by contact of the external surface of 6 the reamer 1 onto the well bore wall. This will result 7 in excessive wear on this area of the roller reamer unit. 8 Retrieval of the tool 13 for replacement of the roller 9 reamer cutter 2 or upper retaining block 5 is both costly 10 and time consuming. Therefore the inclusion of one or 11 more thrust bearings 11 between the roller reamer cutter 12 2 and upper retaining block 5 will minimise thrust which 13 is afforded to this area and therefore reduce wear, but 14 nevertheless will not obstruct the rotation of the roller 15 reamer cutter. Rotation of the roller reamer cutter 2 is 16 permitted by the thrust bearing being a racer, wherein 17 one or more ball bearings can 'race' or 'chase' around 18 the outer circumference of the shaft 3 thereby allowing 19 the roller reamer cutter 2 to rotate with the ball 20 bearings, but relative to the stationary shaft 3 and 21 upper 5 and lower 6 retaining blocks. 22 23 A further advantage lies in the fact that the thrust 24 bearing described in the present invention is a 25 premanufactured bearing which does not have individual 26 components which have to be assembled. It can therefore 27 be readily incorporated into the shoulder of the upper 28 retaining block at the time of assembly of the apparatus 29 with minimum effort. 30 31 Further modifications and improvements may be 32 incorporated without departing from the scope of the 33 invention herein intended.

1 CLAIMS: 2 3 1. A roller reamer tool for mounting on a work string

4 comprising an elongate body having a plurality of 5 recesses positioned circumferentially around said 6 body, each recess being adapted to house a roller 7 reamer unit, wherein said roller reamer unit is 8 comprised of a shaft which is held stationary by an 9 upper and lower retaining means, characterised in 10 that said upper retaining means has a shoulder with 11 thrust bearing means, and wherein the roller reamer 12 unit further comprises a reaming member which is 13 rotatably mounted on the shaft and co-operates with 14 the thrust bearing means in the shoulder of the is upper retaining means. 16

Claims

17

2. A roller reamer tool as described in Claim 1,

18 wherein the reaming member is a roller reamer.

19

3. A roller reamer tool as described in Claims 1 and 2, 21 wherein the reaming member is a roller reamer 22 cutter.

23 24

4. A roller reamer tool as described in any of the preceding Claims, wherein the upper and lower 26 retaining means are bearing blocks.

27 28

5. A roller reamer tool as described in Claim 4, 29 wherein the said upper and lower bearing blocks fit in corresponding pockets in a recess of the roller 31 reamer tool.

32 1

6. A roller reamer tool as described in any of the 2 preceding Claims, wherein the shaft has a 3 longitudinal length which is greater than the 4 longitudinal length of the reaming member.

6

7. A roller reamer tool as described in Claims 3 to 6, 7 wherein the shaft is inserted into a corresponding 8 opening in the upper and lower bearing block.

9

8. A roller reamer tool as described in any one of 11 Claims 4 to 7, wherein the reaming member has a 12 first tapered end which fits within the shoulder of 13 the upper bearing block and co-operates with the 14 thrust bearing means.

is 16

9. A roller reamer tool as described in any of the 17 preceding Claims, wherein the thrust bearing means 18 is a ball bearing racer.

19

10. A roller reamer tool as described in any of the 21 preceding Claims, wherein the shaft has a 22 longitudinally extending bore to allow lubrication 23 of the roller reamer unit.

24

11. A roller reamer tool as described in Claim 10, 26 wherein said longitudinally extending bore 27 communicates with at least one radial outlet.

28 29

12. A roller reamer tool as described in Claim 11, wherein said longitudinally extending bore has 31 pressure creating means for circulating a fluid 32 through the bore.

33 12 1

13. A roller reamer tool as described in Claim 12, 2 wherein said pressure creating means is a piston.

3 4

14. A roller reamer tool as described in any of the preceding Claims, wherein the roller reamer tool 6 includes connection means for mounting the roller 7 reamer tool on a work string.

8 9

15. A roller reamer tool as described in Claim 14, wherein said connection means are threaded end 11 connections.

12 13

16. A roller reamer tool as described in any of the 14 preceding Claims, wherein the reaming member is made is of a hard wearing and resistant material such as 16 tungsten carbide or polycrystalline diamond.