GB2373529A

GB2373529A - Well cleaning tool

Info

Publication number: GB2373529A
Application number: GB0214063A
Authority: GB
Inventors: Mark Carmichael; Paul Howlett
Original assignee: SPS Afos Group Ltd
Current assignee: Schlumberger UK Holdings Ltd
Priority date: 1998-04-21
Filing date: 1999-04-21
Publication date: 2002-09-25
Anticipated expiration: 2019-04-21
Also published as: GB0214063D0; GB9909027D0; GB2336612A; GB2373529B; GB2336612B

Abstract

Well cleaning apparatus 1 comprises a tubular member 2 attached to a work string which supports one or more resilient cleaning members 5. Each cleaning member forms a continuous sealing surface with the well casing, and is provided with a means for allowing fluid bypass. The apparatus is passed down the well casing in the manner of a plunger, driving debris-containing fluid into a central bore. The fluid is then pumped to the surface, where debris is filtered out, and then clean fluid is returned to the well.

Description

1 2373529

I Well clean-up tool with improved cleaning member 3 This invention relates to well cleaning apparatus and, 4 more generally, to apparatus used for the cleaning of the insides of pipes, tubes, liners and the like.

7 It is considered desirable when drilling for oil or gas 8 to maintain a clean interior in the casing or liner of 9 the drilling well. For this purpose, well cleaning 10 apparatus is well known and comes in a variety of 11 different forms. One such type of well cleaning 19 apparatus is generally known as a casing scraper. This 13 type of tool typically incorporates steel casing scraper 14 blades that scrape the inside of the casing or tubing in 1: the well. A second type of well cleaning apparatus known i6 in the art may be more accurately likened to a brush and 17 incorporates cleaning pads with protruding bristles.

18 Brushing tools are generally used to clean well casings, 19 tubing and the like of smaller debris and or particles 9() than that of scraper tools.

90 The present invention recognizes that these and other 0 clean up tools are not entirely satisfactory in cleaning

1 all areas in well tubing. For example, where threads or 2 joints exist, the inside surface of the tubing may be 3 slightly irregular leading not only to increased 4 entrapment of mud or debris, but the diminished 5 accessibility of known clean up tools. Also, many well 6 cleanup tools are not particularly suited to low 7 tolerances in the tubing ovality.

g 9 An object of the present invention is to provide an 10 alternative type of cleaning member on a clean-up tool 11 used in well tubing and the like that provides improved 19 penetration and cleaning in at least certain 13 applications. From the description herein it will be

14 seen that the invention provides other advantages over 15 known art. For example, another disadvantage of the 16 aforedescribed tools is that although they may be 17 relatively efficient at removing particles from the 18 casing wall, they do not necessarily prevent the debris 19 from then remaining suspended in the well fluid even if 20 the fluid is circulated through the well, not all of the 21 debris is flushed out the surface. Thus, even where 29 filters are provided to clean the well fluid, these may 23 not be entirely effective as debris may remain suspended 24 below the surface in the well.

26 In order to address this deficiency, other tools have 27 been designed and manufactured which are intended to 28 catch and/or trap the debris suspended in the circulation 29 fluid. One example of this type of tool is described in 30 our co-pending British Patent Application No 9806274.8.

3] However, again while such tools mitigate the problem, 30 they are not completely deficient and can also retard 33 circulation in the well.

1 Accordingly, the present invention results from the 2 additional recognition of a need to provide better 3 apparatus and methodology for cleaning the annulus 4 between a drilling string or work string and a casing 5 string. Indeed, it is an object of the present invention 6 to provide improved apparatus and method for cleaning 7 casing string that is also adapted to clean the annulus 8 between the work string and the casing string.

9 Specifically, an object of the present invention is to 10 remove suspended debris and particles from the 11 aforedescribed annulus.

13 According to a first aspect of the invention herein there 14 is provided a method of cleaning a well, the method 15 including the step of running a work string into the 16 well, the work string supporting one or more cleaning 17 members adapted to plunge the well by sealably engaging 18 the well casing such that the majority or substantially 19 all of the well fluid below the one or more cleaning 20 members is caused to flow up a bore or channel provided 21 in the work string to surface.

23 The method may further include cleaning the well casing 24 wall by the contact of the cleaning members thereon. The 25 contact may be a scrubbing action.

27 The method may further include sucking the well fluid up 28 the work string using a vacuum system or pump.

30 The method may further include filtering the well fluid, 31 preferably at surface and thereafter directing the fluid 32 back into the well.

t t

I The method may further include pressuring up behind the 2 or each cleaning member so as to rupture a disc to enable 3 fluid bypass after plunging the well.

Further there is provided well cleaning apparatus 6 comprising a tubular body member adapted for attachment 7 to a work string, the body member supporting one or more 8 resilient and pliable cleaning members biased in an 9 outward radial direction to enable a generally planar 1() surface of the or each cleaning member to contact the 1I well casing or other tubing in use, the one or each 12 cleaning member being made from a foam, polymeric or 13 rubber material, and wherein the apparatus further 14 includes bypass means for selectively enabling the 1: circulation of fluid past the cleaning members when 16 desired.

IS The cleaning member may be made from an elastomer and 19 more specifically a thick walled polyurethane elastomer.

21 Preferably, the or each cleaning member is provided in 22 the form of a cup that typically is positioned in a 23 concave down orientation when the apparatus is suspended 24 vertically in a well. Alternatively, the or each 2: cleaning member may be an inflatable bladder.

27 The cleaning member may co-operate with the body member 28 so as to create the said outward radial bias, in use.

29 For example, the inflatable bladder may be suspended in 30 compression during a cleaning operation between two 3I portions of the body member.

A_

( s I Alternatively, the cleaning member may be formed with an 2 inherent radial resilience that is maintained in radial; 3 compression in use.

5 Preferably, an abrasive and hard wearing surface is 6 provided on the exterior of the cleaning member.

7 Typically, the cleaning member would be manufactured as a 8 composite, with the abrasive surface being adhered or 9 welded to the outer surface of the cleaning member.

1I Preferably, the or each cleaning member sealably engages 12 the inside wall of the casing or other tubing.

14 The bypass means may be provided as a rupturable disc or IS portion within the or each cleaning member.

16 Alternatively, the by-pass means may be formed as a 17 channel in the body member.

19 Also there is provided a well cleaning system comprising 20 a tool having a tubular body member adapted for 21 attachment to a work string, the body member supporting 22 one or more resilient and pliable cleaning members biased 23 in an outward radial direction to enable a generally 24 planar surface of the or each cleaning member to sealably 25 contact the well casing or other tubing in use, the one 26 or each cleaning member being made from a foam, polymeric 27 or rubber material, wherein the tool further includes 28 bypass means for enabling the circulation of fluid past 29 the cleaning members when desired, and means for closing 30 said bypass, and the body member including a generally 31 axial bore therethrough, wherein the bore communicates 32 with a flow path to the surface of the well via the work 33 string.

1 The apparatus may be associated with filtration means, 9 that typically may be located at surface.

4 The apparatus may also be associated with vacuum or 5 sucking means for providing suction of well fluid up the 6 bore through the work string.

8 In order to provide a better understanding of the 9 invention, various embodiments thereof will now be 10 described, by way of example only, and with reference to 11 the following Figures, in which: 13 Fig. l shows a half sectional elevation of a first 14 embodiment of a well cleanup tool for carrying out ]5 the invention; 17 Figure 2 shows an alternative embodiment of well 18 cleanup tool; and 20 Figure 3 is a schematic diagram illustrating a well 91 cleanup system.

23 Referring firstly to Figure l, a relatively simple well 24 cleanup tool is generally depicted at 1. The simple 25 construction of the tool l is seen as a benefit in the 26 commercial exploitation, construction and maintenance of 27 the tool.

29 The tool l comprises a body member 2 supporting a sleeve 30 3. The sleeve 3 is moveable in an axial position relative 31 to the body member 2 and is generally operable between a 32 first position at which it substantially abuts a shoulder 33 4 on the body member 2 and a second position at which it 34 it does not so abut the shoulder 4.

1 Bonded to the sleeve 3 is a cleaning member in the form 2 of an inflatable bladder 5. The bladder is provided with 3 a hard and robust surface coating and made of a suitably 4 toughened fabric to avoid puncture or premature wear.

6 It is to be seen that when the sleeve is in the aforesaid 7 first position, the bladder 5 is axially compressed and 8 biased outwardly into contact with the casing wall (not 9 shown). Conversely, when the sleeve 3 is in the second 10 position, the bladder does not tend to bulge outwardly 11 and thus is allowed to come out of contact with the 12 casing. Thus the cleaning member 5 is able to expand and 13 contract axially and therefore radially by co-operation 14 of the sleeve 3 with the shoulder 4.

16 An advantage of this particular embodiment therefore is 17 that it is possible to manipulate the tool l so that the 18 cleaning member 5 does not contact the inner surface of 19 the liner or other well tubing. This is desirable when, 20 for example, the tool l is being retracted from the well 21 and it would be detrimental to dislodge any further 22 debris or mud.

24 Yet further, the axial expansion or contraction of the 25 bladder 5 allows the degree of contact pressure of the 26 cleaning member 5 on the well tubing to be manipulated to 27 suit conditions. When the sleeve 3 is in the first 28 position, the bladder 5 will be also be axially 29 compressed and thus squeezed outwardly causing maximum 30 contact and pressure of its cleaning surfaces on the 31 inner surface of the well tubing. Raising the sleeve 3 32 slightly will reduce the pressure of inflation of the 33 cleaning member 4 and this will therefore render the 34 cleaning member more pliable, enabling it to better

1 access any pits, grooves, threads or the like where 2 debris may be trapped.

4 The body member 2 is attachable in a work string (not 5 shown) by the provision of box threads 6a and 6b.

7 Fluid by-pass is enabled through an annulus formed 8 between the sleeve 3 and the body member 2.

10 In the example embodiment illustrated in Figure l, the 11 cleaning member 5 is made from a non-rigid and pliable 12 polymer and inflated with air. If beneficial, an 13 inflation tool (not shown) may be located in the body 14 member 2 or sleeve 3 communicating with the inside of the 15 inflatable compartment that is the cleaning member.

17 However, perhaps the most significant advantage of this 18 feature of the first described embodiment is that a 19 clean-up tool of this design can be used to clean a 20 diverse range of tube diameters, without the need for the 21 adjustment or replacement of parts. The pliable nature 22 of the bag like cleaning member is adapted to conform to 23 or adopt the internal diameter of the tubing, simply 24 through the appropriate manipulation of the sleeve 3.

2: 26 Turning now to Figure 2, an alternative cleanup tool is 27 shown and generally depicted at lO. The tool lO is again ?8 provided with a generally axial and tubular body member ?9 11 having means for attachment in a string at its axial 30 extremities 12.

32 The body member ll carries two cup-shaped cleaning 33 members 13,14 made from a semi-rigid plastics material 34 and, specifically, coated polyurethane. The cups may be

l moulded in factory conditions and have excellent physical 2 and chemical resistant properties.

4 In the embodiment shown, the cups 13,14 are both 5 positioned with their open ends facing in a down-hole 6 direction in order to reduce the dislodgement of debris 7 when the tool 10 is being retracted out of the well.

8 However, the invention is not to be construed as having 9 this limitation and in an alternative embodiment the cups 10 may each be provided in either a concave up or concave ll down orientation. Similarly any number of cups may be l' used.

14 The outer rims or walls 15 of the cups 13,14 may be 15 coated with a hard wearing and abrasive material. This 16 may be provided by incorporating abrasive particles into 17 the material during moulding. Alternatively, as shown in lS Figure 2, the cups 13,14 may be manufactured in a 19 composite form, having an outer layer or ply with 20 abrasive and wear resistant properties.

22 The outer walls or sides of the cups 13,14 are sized to 23 be radially compressed by the well tubing walls in use.

24 This ensures that they impart a suitable force to the 25 surfaces to be cleaned, even when the walls of the cups 26 begin to wear, thereby allowing for an aggressive 27 cleaning operation.

99 The cups 13,14 are provided with rupture discs 16 which, 30 when ruptured, allow for the circulation of fluid through 31 the cups. Rupturing of the discs 16 may be accomplished 32 by pressuring up above the cups to a predetermined 33 rupture pressure.

lo I It may be seen that a feature of the present invention is 9 that the cleaning members used are generally adapted to 3 present a planar surface and not of the type found in the 4 art which present points or edges to the tubing to be 5 cleaned. This allows for a much improved scrubbing 6 action to be achieved. Moreover, this feature, coupled 7 with the nature of the materials encompassed within the invention, provide increased coverage and access to 9 remote or protected areas of the casing or liner.

1I The tool 10 may be used in the following way. Firstly it 12 may be attached to the end of a work string or drill 13 string and then run in a well. As it is lowered into the 14 well, the cups 13,14 sealably press against the casing 15 wall and as there is no bypass provided for circulation, l6 the cups serve to plunge the well. Fluid in the well and 17 importantly, and debris in the well fluid, is forced up 18 the axial bore that runs through the tool body member 11 19 and then further up the work string to surface. Once this 20 plunging of the well has been completed, the fluid above 2I the cleaning members may be pressurized to a sufficient 22 extent to rupture the discs 16, thereby enabling 23 circulation.

25 In Figure 3 the cleaning system is depicted schematically 26 and in the example there is provided a well 20 with a 27 work string 21 suspended in the well 20. The work string 28 21 supports a tool 22 comprising of a body member 23, 29 brushes 24 and plunging cup 25.

31 At the top or the well is provided a vacuum pump 26 which 32 assists by siphoning fluid up the work string 21. The 33 fluid is then passed through filtration means 27 and the 34 clean Fluid directed back into the well.

Claims

I CLAIMS:

3 1. A method of cleaning a well casing or other tubing 4 in a well, the method including the step of running 5 a work string into the well, the work string 6 supporting one or more cleaning members adapted to 7 plunge the well by sealably engaging the well casing g such that the majority or substantially all of the 9 well fluid below the one or more cleaning members is 10 caused to flow up a bore or channel provided in the 11 work string to surface.

13
2. A method as claimed in Claim 2 further including

14 cleaning the well casing wall by the contact of the 15 cleaning members thereon.

17
3. A method as claimed in Claim l or Claim 2 further 18 including sucking the well fluid up the work string 19 using a vacuum system or pump.

21
4. A method as claimed in any one of Claims l to 3 22 further including filtering the well fluid, at 23 surface and thereafter directing the fluid back into 24 the well.

26
5. A method as claimed in any one of Claims l to 4 27 further including pressuring up behind the or each 28 cleaning member so as to rupture a disc to enable 29 fluid bypass after plunging the well.

31
6. Well cleaning apparatus for carrying out the method 39 of any one of Claims l to 5, comprising a tubular 33 body member adapted for attachment to a work string, 34 the body member supporting one or more resilient and

! 12 l pliable cleaning members biased in an outward radial 9 direction to enable a generally planar surface of 3 the or each cleaning member to contact the well 4 casing or other tubing in use, the one or each j cleaning member being made from a foam, polymeric or 6 rubber material, and wherein the apparatus further 7 includes bypass means for selectively enabling the 8 circulation of fluid past the cleaning members when 9 desired.

11
7. Well cleaning apparatus as claimed in Claim 6, 19 wherein the or each cleaning member is made from an 13 elastomer.

15
8. Well cleaning apparatus as claimed in Claim 6 or 16 Claim 7, wherein at least one of the or each 17 cleaning member is provided in the form of a cup 18 that typically is positioned in a concave down 19 orientation when the apparatus is suspended 20 vertically in a well.

29
9. Well cleaning apparatus as claimed in Claim 6 or 23 Claim 7, wherein at least one of the or each 24 cleaning member is an inflatable bladder.

26
10. Apparatus as claimed in any one of Claims 6 to 9, 27 wherein the or each cleaning member co-operates with 28 the body member so as to create the said outward 29 radial bias, in use.

31
ll. Apparatus as claimed in any one of Claims 6 to 10, 39 wherein the cleaning member is formed with an 33 inherent radial resilience that is maintained in 34 radial compression in use.

1
12. Apparatus as claimed in any one of Claims 6 to 11, 2 wherein an abrasive and hard wearing surface is 3 provided on the exterior of the or each cleaning 4 member.

6
13. Apparatus as claimed in Claim 12 wherein the 7 cleaning member is manufactured as a composite, with 8 the abrasive surface being adhered or welded to the 9 outer surface of the or each cleaning member.

11
14. Apparatus as claimed in any one of Claims 6 to 13, 12 wherein the or each cleaning member sealably engages 13 the inside wall of the casing or other tubing.

15
15. Apparatus as claimed in any one of Claims 6 to 13, 16 wherein the bypass means is provided as a rupturable 17 disc or portion within the or each cleaning member.

19
16. Apparatus as claimed in any one of Claims 6 to 14, 20 wherein the by-pass means is formed as a channel in 21 the body member.

23
17. A well cleaning system for carrying out the method 24 of any one of Claims l to 5, comprising a tool 25 having a tubular body member adapted for attachment 26 to a work string, the body member supporting one or 27 more resilient and pliable cleaning members biased 28 in an outward radial direction to enable a generally 29 planar surface of the or each cleaning member to 30 sealably contact the well casing or other tubing in 31 use, the one or each cleaning member being made from 32 a foam, polymeric or rubber material, wherein the 33 tool further includes bypass means for enabling the 34 circulation of fluid past the cleaning members when

] desired, and means for closing said bypass, and the 2 body member including a generally axial bore 3 therethrough, wherein the bore communicates with a 4 flow path to the surface of the well via the work 5 string.

7
18. A system as claimed in Claim 17 further including filtration means, that typically may be located at 9 surface.

11
19. A system as claimed in Claims 17 or 18 further 12 including vacuum or sucking means for providing 13 suction of well fluid up the bore through the work 14 string.