GB2338734A

GB2338734A - Down-hole tool with detachable cleaning pads

Info

Publication number: GB2338734A
Application number: GB9914547A
Authority: GB
Inventors: Mark Carmichael; Paul David Howlett
Original assignee: Specialised Petroleum Services Ltd
Current assignee: Schlumberger UK Holdings Ltd
Priority date: 1998-06-23
Filing date: 1999-06-23
Publication date: 1999-12-29
Anticipated expiration: 2019-06-23
Also published as: GB2338734B; US6343648B1; GB9914547D0; GB9813422D0

Abstract

A down-hole tool for use in an oil or gas well is provided with detachable components 5 that are held to a body or tool housing 1 by longitudinal mechanical fasteners 2 disposed in a generally radial orientation. The mechanical fasteners 2 allow for the components to be quickly removed and refurbished or replaced, while also permitting radial movement or floating of the components during operation of the tool. A spring 3 or other biasing means may be incorporated to bias the components in a radial outward direction during operation.

Description

1 1 DOWN-HOLE TOOL WITH DETACHABLE CLEANING PADS 2 3 This invention

relates to equipment intended for use in 4 down hole environments, such as may typically be found in 5 oil and gas wells. The invention has a particular application in connection with well casing cleaning apparatus.

2338734 7 8 9 There are a several operations performed down-hole that 10 may lead to the wear or damage of particular components 11 of a tool. The present invention recognises therefore 12 that it would be advantageous to design a means for the 13 easy and cost efficient replacement or repair of such 14 components. An object of the invention therefore is to provide certain components prone to premature wear or 16 damage in a manner which allows them to be detached from 17 the main body of the tool. Moreover, a related and yet 18 further object is to provide an improved retaining means 19 for retaining detachable components or consumables to the 20 body of a respective down-hole tool. 21 22 23 24 The retaining means should allow for the convenient and efficient removal and replacement of a component or consumable, while also allowing for the effective use and 2 1 operation of the component during the normal operation of 2 the tool.

3 An example of the type of component that has been found advantageous to retain in a detachable manner is a pad 6 used to support bristles on a casing brush. A casing 7 brush or brushing tool as it is also known in the 8 industry is a type of well clean up tool, designed for 9 producing a clean interior in the casing or liner of the drilling well. The pads support a bed of wire bristles 11 and are typically biased outwardly by compression springs 12 or the like that cause the bristles to bear forcibly on 13 the casing wall. The pressure of the pads on the casing 14 lead to the wear of the bristles and warrants bristle replacement or repair.

16 17 18 19 21 22 23 24 26 27 28 29 31 32 33 In British Patent Application Number 2,299,599, there is described well cleaning apparatus which has a body member to which is attached, preferably, a plurality of cleaning pads spaced circumferentially around the body member. The pads are provided with bristles on their outer face and are biased outwardly by coil springs or similar means in an attempt to maintain a sufficient contact pressure of the bristles on the interior wall of the casing.

British Patent Number GB 2,295,632 describes an alternative brushing tool which incorporates bristles that protrude from raised rib-like portions on a body member.

An alternative well clean up tool is generally known as a casing scraper. This type of tool typically incorporates casing scraper blades that scrape the inside of the 3 1 casing or tubing in the well. The steel blades-may also 2 be mounted on detachable pads, plates or the like.

3 4 An object of the present invention is to provide an improved means of retaining pads supporting brushes, 6 scraper blades or the like.

7 8 According to the present invention, there is provided a 9 downhole tool comprising a generally tubular body member and one or more detachable pads, the one or more pads 11 each being retained to the body member by a retaining 12 means provided as a plurality of longitudinal mechanical 13 fasteners disposed in a generally radial orientation in 14 use and positioned so as to correspond with and pass through respective apertures provided in the pads, 16 wherein the mechanical fasteners each engage the body 17 member and limit the radial movement of the pad away from 18 the body member.

19 21 22 23 24 Typically the mechanical fasteners are bolts or threaded 26 rods. They may be formed with a bolt head or may be 27 associated with retaining nuts or the like. The apertures 28 may be countersunk on the outer face of the pad to 29 provide a recess for the bolt head or retaining nut.

31 32 33 34 Preferably each pad is provided with a said aperture in the vicinity of each of its corners and is retained in use to the body member by a mechanical fastener at each said aperture.

The tool may further include biasing means for biasing the or each pad in an outward radial direction, wherein the biasing means comprise springs held under compression in use.

4 1 2 The springs may be coil springs or leaf springs for 3 example. Preferably, where the springs are provided as 4 coil springs, some or all of the springs may be located over the mechanical fasteners. In any event, the springs 6 are preferably located toward the peripheral edges of the 7 pad. This has the advantage of promoting an even or 8 balanced outward bias on the pad.

9 Typically, the pads support one or more cleaning members on their outer face for cleaning casing strings. The cleaning members may be bristles or scraper blades for example.

11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 The pads 5 support a bed of bristles 4 for brushing the 31 inside wall of a casing string or other well tubing (not 32 shown).

33 In order to provide a better understanding of the invention, example embodiments will now be described with reference to the accompanying figures, in which:

Figure 1 shows a downhole tool supporting three cleaning pads, the cleaning pads bearing respective brushes for brushing well casing; and Figure 2 shows an exploded view of an alternative pad and retaining means removed from the tool body.

Referring firstly to Figure 1, a down-hole tool attachable to a work string comprises a generally cylindrical body member 1 which incorporates three receptacles 7 for locating detachable cleaning pads 5.

1 The pads 5 are held in position in respective receptacles 2 by retaining means, including four bolts 2. The head of 3 the bolts 2 are positioned outwardly in a radial 4 6 7 direction, with the shank of the bolts 2 being inserted through respective apertures 8 in the pads 5 and engaging female threaded bores in the body members 1.

8 It may be seen that the bolt heads nest in the 9 countersunk cavities of the apertures_ 8. In this way the 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 bolt heads do not protrude beyond the outer face of the pads 5, ensuring they do not foul on the casing wall.

The pads 5 are biased in an outward radial direction by the coil springs 3. The springs 3 are located over the bolts 2 and provide a compressive force between the body member 1 and the inner f ace of the pads 5. One advantage of the springs being placed over the bolts 2 lies in the fact that the springs are not easily removed from the tool during use. The present invention recognises that the dislodgement or inadvertent removal of the springs is extremely contrary to the overall purpose of the tool.

Yet further, the positioning of the springs 3 in close association with the mechanical fasteners serves to tighten the fasteners 2 or more specifically the thread tension, together with the interface between the bolt head and the pads. Although not clearly shown in Figure 1, tension nuts may be provided between the bolt head and the pad 5 to act against the compressive force of the spring 3 when it is desired to remove a pad 5 from the tool body member 1. The tension nuts preferably would be of greater diameter than the bolt heads to ensure easy access to them.

6 1 The bolts 2 are each positioned in the vicinity of a 2 respective corner of the pad 5. This has the advantage 3 4 6 7 8 The pads 3 are provided over two rows on the body member 9 1; there being provided a bypass area between each pad for circulation purposes in the well. Typically, the 11 pads 6 on the first row are circumferentially offset from 12 the pads on the second row.

13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 of maintaining the pads 5 in a balanced state, whereby they address the casing wall squarely and not in a tilted manner as may be the case where the pads are retained in their middle or at only one or two edges thereof.

Turning now to Figure 2, there is shown an exploded sectional view of an alternative pad 10, the pad supporting casing scraper blades 11. As before, the pad 10 is provided with four countersunk apertures 12, located generally at the four corners of the pad 10.

However, the pad 10 is provided with two springs seats 12 for locating biasing means in the form of leaf springs 14. The seats 13 are again positioned generally adjacent to the perimeter or edges of the pads.

The retaining means illustrated in Figure 2 consist of a plurality of threaded rods 15 that are permanently fixed to the body member 16 at one end. The free end of the rods 15 are adapted to be inserted through the apertures 12 of the pad 10 such that the pad 10 may be secured to the body member 16 by threading on to the rods 15 the retaining locking nuts 17.

A further advantage of the invention is that the inadvertent failure of breakage of one of the mechanical 7 1 fasteners does not lead to the total redundancy of the associated pad; the other mechanical fasteners serving to continue to retain the pad in position and allow for its continued performance.

In the embodiments shown, the pads may be simply and quickly removed from the body member of the tools by 8 unscrewing the bolts or retaining nuts.

9 10 11 12 13 14 Further modifications and improvements may be incorporated without departing from the scope of the invention herein intended.

Claims

1 Claims: 2

3 1 4 5 6 7 8 9 10 11 12 13 14

2. 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 8 A down-hole tool comprising a generally tubular body member and one or more detachable pads, the one or more pads each being retained to the body member by a retaining means provided as one or more longitudinal mechanical fasteners disposed in a generally radial orientation in use and positioned so as to correspond with and pass through respective apertures provided in the pads, wherein the one or more mechanical fasteners each engage the body member and limit the radial movement of the pad away from the body member.

A down-hole tool as claimed in Claim 1 wherein each pad is provided with a said aperture in the vicinity of each of its corners and is retained in use to the body member by a mechanical fastener at each said aperture.

3. A down-hole tool as claimed in Claim 1 or Claim 2 wherein the mechanical fasteners are bolts or threaded rods.

4. A down-hole tool as claimed in Claim 3 wherein the one or more mechanical fasteners are formed with a bolt head or are adapted to engage with retaining nuts.

5. A down-hole tool as claimed in claim 4 wherein the apertures are countersunk on the outer face of the pad to provide a recess for the bolt head or retaining nut.

9 1 6. A down-hole tool as claimed in any one of the 2 preceding Claims further including biasing means for 3 biasing the or each pad in an outward radial 4 direction, wherein the biasing means comprise springs held under compression in use.

6

7 7. A down-hole tool as claimed in claim 6 wherein the

8 springs are coil springs.

9 8. A down-hole tool as claimed in Claim 6 wherein the 11 springs are leaf springs.

12 13 14 is 16 17 18 19 21 22 23 24 26 12. A down-hole tool as claimed in Claim 11 wherein the 27 cleaning members are bristles or scraper blades.

28 9. A down-hole tool as claimed in Claim 7 wherein some or all of the springs may be located over the mechanical fasteners.

10. A down-hole tool as claimed in any one of Claims 6 to 9 wherein the springs are located toward the peripheral edges of the pad.

11. A down-hole tool as claimed in any one of the preceding Claims wherein the pads support one or more cleaning members on their outer face for cleaning casing strings.