GB2424235A - Modular downhole tool - Google Patents

Abstract

A multi-function downhole tool 10 comprises a tubular body having at least one recess 11 formed in an outer surface thereof. The recess is adapted to receive each of a set of interchangeable tools. The tools may include stabiliser blades 102, a cleaning element (112, fig 3), a roller reaming tool element (152, 156, fig 9) or a drilling casing shoe. Alternate sizes of stabiliser blade may be substituted for use in wellbores of different size. The tool may include ribs 15 forming flow channels 14. In another aspect a tubular body has a recess in an outer surface and a removable tool element is received in the recess and is upstanding from the outer surface of the body. The removable tool element is attached to the body by a mechanism extending from a side wall of the tool, passing through the tool and into the tubular body.

Description

1 Multi-function downhole tool 3 The present invention relates to downhole

tools used in 4 welibores, and, in particular, to downhole tools used in rotary operations.

7 A number of different types of downhole tools and 8 equipment are used in the oil and gas exploration and 9 production industry during the drilling of a weilbore, lining of the drilled bore with a metal casing/liner, and 11 in the subsequent completion of the well to gain access 12 to subterranean hydrocarbon bearing rock formations.

14 These tools and equipment include, for example, drill strings used in the drilling of a weilbore; stabilisers 16 and centralisers used for centralising equipment in a 17 borehole or downhole tubing; reamers and other cutting 18 tools used for reaming a drilled borehole wall; and 19 cleaning tools used for cleaning downhole tubing fl preparatory to completion of a well or in an intervention 21 procedure.

1 In the oil and gas exploration industry, numerous 2 welibores are drilled and maintained with the assistance 3 of different types of downhole tools. Such tools are 4 mounted on or incorporated into a string for use in various well bore operations. Such a string could for 6 example be a drill string where it is be usual for the 7 string to be rotated within the well bore. Another 8 tubular string commonly encountered in such operations is 9 a casing string.

11 In drilling operations, bottomhole assemblies are 12 provided toward the downhole end of the string and are 13 typically provided with stabiliser tools. These 14 stabilisers provide a stand-off of the string from the wellbore walls as their outer surface is juxtaposed the 16 wellbore walls. Stabilisers help to keep the drill pipe 17 or heavyweight drill pipe and drill collar from the well 18 bore wall reducing friction, maintain the drill bit in 19 the correct position within the welibore, and thus help to maintain torque on the drill bit.

22 Known drill string stabilisers are typically cylindrical 23 tubular elements which are fitted around the drill pipe 24 or provided integrally with the pipe, and often include grooves to allow fluid to pass relatively unrestricted 26 upwards through the well borehole. Some known 27 stabilisers have helical groove channels extending around 28 the body of the pipe.

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In a similar fashion, drill collars of a bottomhole 31 assembly may carry integral stabiliser arrangements of a 32 similar structure, or a stabiliser arrangement of this 33 type may be provided above the drill bit, for a similar 1 purpose of helping to remove fluid and debris away from 2 the drill bit or a drill shoe of the assembly and along 3 the welibore annulus to surface.

Grooved stabiliser elements are also used during reaming, 6 which is either a secondary drilling process for re- 7 entering an existing wellbore, for example for enlarging 8 the weilbore diameter, or for ensuring a drilled borehole 9 is of a desired diameter.

11 Cleaning tools are also often applied at various points 12 on the string and are provided with a scouring or 13 scraping outer surface for removing residue from the 14 insides of the wellbore walls or inside walls of casing.

16 Strings run in casing are typically equipped with 17 protecting sleeves. Further, casing strings are provided 18 with tubular centralisers that keep the casing central in 19 the weilbore with an annular space between the outer surface of the casing and the wellbore walls.

22 The downhole tools and various string elements must be 23 constructed such that they can withstand the forces that 24 they may be subjected in a wellbore whilst performing their specific functions within the string. Ideally, the 26 elements are able to function while other wellbore 27 procedures are carried out simultaneously, thus 28 maximising efficiency. During operation of a string in a 29 wellbore, fluid is typically pumped down through the S...

centre of the string at pressure causing the fluid to is:.

31 return back up through the outer wellbore annulus 32 flushing out cuttings and debris. It is therefore 33 important for a stabiliser tool used during drilling to 1 accommodate the passage of drilling fluid from the 2 rotating drill bit through the annulus between the 3 welibore wall and the string. Similar performance is 4 required of cleaning tools, centralisers and other downhole tools.

7 Typically, in drilling and cleaning operations, a 8 particular tool is designed and configured for a specific 9 task in a wellbore. Indeed, for drilling, stabilising, centralising and clean-up operations, the tools may be of 11 a specific outer diameter corresponding to the inner 12 diameter of the bore or casing in which they are run.

13 When the wellbore has sections at depths of decreasing 14 inner diameter, it may be necessary to remove the tool and replace with a different tool of appropriate 16 dimensions.

18 Such downhole tools are often incorporated as individual 19 sections into a string. Changing out tools that have become worn or introducing new tools to the string to 21 deal with unexpected problems can therefore result in a 22 lengthy and costly operation. It is desirable to be able 23 to expeditiously react and replace and introduce tools as

24 required in the field.

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26 Various proposals for downhole tools have been documented 27 that address some of the above issues. United States 28 Patent number US 4,190,124 (Taylor) provides details of a 29 stabiliser with blades that are removable. The blades fix into longitudinal slots provided on planar components 31 of the stabiliser main body. The planar components are: 32 surfaces extending longitudinally and which are 33 effectively ridges with corresponding low relief valley 1 channels formed in between and allowing fluid to flow 2 past.

4 International Patent Publication Number WO 91/05936 (Weatherford) discloses a centraliser, stabiliser, or 6 pipe protector having a fluted tubular cylindrical outer 7 surface that directs and channels fluid flow upwards 8 through the weilbore. The channels may create a helical 9 path for the fluid. Protruding ribs create an annular space between a string and the welibore wall and enhance 11 turbulence of the fluid and material flowing past the 12 exterior surface of the device.

14 Further proposed systems include a downhole tool for cleaning operations having detachable cleaning pads.

16 These are fastened in place with a nut and bolt. The 17 purpose is to be able to quickly replace worn brushes 18 should it be necessary during operations. The cleaning 19 pads may be equipped with brushes or scrapers.

21 Although prior art systems have addressed some important 22 issues, problems persist with current equipment causing 23 much downtime during drilling operations. One particular 24 such problem during rotary drilling is differential sticking of the pipe to the wellbore wall, which is 26 particularly common when drilling through clay rich 27 formations and when well pressure is greater than 28 formation pressures. Further, such formations cause 29 balling', which is the effect of solids such as clays sticking to various tool components due to pressure 31 effects. These effects prevent the tools from operating 32 properly and may drive the drill string to a halt.

1 It is therefore desirable to provide a downhole apparatus 2 that obviates or at least mitigates some of the drawbacks 3 of associated with prior art downhole tools and methods.

It is amongst the aims and objects of the invention to 6 provide a downhole apparatus capable of providing a body 7 upon which a variety of tool assemblies can be 8 configured.

According to a first aspect of the invention, there is 11 provided multi-function downhole apparatus comprising: 12 a tubular main body; 13 at least one recess formed in an outer surface of the 14 body, the recess adapted to receive each of a set of interchangeable tool elements, wherein the set of 16 interchangeable tool elements comprises any two of a 17 stabiliser blade, a cleaning element, and a roller 18 reaming tool element.

In this context, the term cleaning element should be 21 construed broadly and includes elements, components or 22 assemblies providing a cleaning, scraping, scouring, or 23 brushing function in a wellbore. This includes debris or 24 junk collection elements, and magnetic components configured for junk or debris collection.

27 According to a second aspect of the invention, there is 28 provided a method of configuring a multi-function 29 downhole apparatus, the method comprising the steps of: S...

- Removing a first tool element from a recess in a 31 tubular body; : 32 Removably attaching a second tool element, different 33 from the first, to the recess in the tubular body; 1 Wherein the first and second tool elements are any two 2 selected from a stabiliser blade, a cleaning element, and 3 a roller reaming tool element.

The method allows the same tubular body to be configured 6 as a cleaning tool, a stabiliser tool, or a roller 7 reaming tool.

9 The tool may comprise a first set of recesses circumferentially distributed around the body.

12 In one embodiment, the tool comprises a second set of 13 recesses circumferentially distributed around the body in 14 a location longitudinally displaced from a first set of recesses on the body.

17 Preferably, the second set of recesses is rotationally 18 offset with respect to the first set of recesses. In 19 this way, the first and second set of recesses together provide an increased circumferential coverage of the tool 21 elements when the tool is being run in the wellbore.

23 In one embodiment, the tool comprises a magnetic tool 24 element. The magnetic tool element may be received in w.

the recess. The radial dimension of the magnetic tool 26 element may be less than the depth of the recess such 27 that the outer surface of the magnetic tool insert is 28 inset with respect to the outer dimension of the 29 apparatus. In this way, the apparatus provides a pocket for the collection of debris, junk and cuttings from the 31 wellbore.

1 According to a third aspect of the invention, there is 2 provided a method of configuring a downhole apparatus, 3 the method comprising the steps of: 4 - Removing a first tool element from a recess in a tubular body; 6 - Removably attaching a second tool element to the 7 recess in the tubular body; 8 Wherein the first tool element is a stabiliser blade 9 having a first radial dimension for running in a weilbore of first inner diameter, and the second tool element is a 11 stabiliser blade having a second radial dimension, 12 different from the first, for running in a weilbore of 13 second inner diameter.

The method allows the same tubular body to be used as a 16 stabiliser tool in weilbores, casings and linings of 17 different inner diameter.

19 According to a fourth aspect of the invention there is provided downhole apparatus comprising: 21 a tubular main body; 22 at least one recess formed in an outer surface of the 23 body, the recess adapted to receive a removable tool 24 element; wherein the body is provided with at least one bore for 26 coupling a removable tool element, and the bore is 27 aligned on an attachment axis inclined with respect to a 28 radial axis of the body. a...

Preferably, the recess is formed to extend radially of a::..

31 the body. More preferably, the apparatus is adapted to 32 receive a removable tool element extending radially of 33 the body.

2 By inclining the attachment axis the need to provide a 3 screw or bolt extending the entire depth of the removable 4 tool element is avoided. In addition, the attachment axis can be aligned such that forces encountered during 6 wellbore operations have an increased axial component.

8 According to a fifth aspect of the invention there is 9 provided a downhole assembly comprising: a tubular main body; 11 at least one recess formed in an outer surface of the 12 body; 13 a plurality of interchangeable tool elements comprising 14 of any two of selected from group of: a stabiliser blade of a first radial dimension, a stabiliser blade of a 16 second radial dimension, a cleaning element, and a roller 17 reaming tool element; 18 wherein the recess is adapted to receive the each of the 19 plurality of interchangeable tool elements during a different mode of operation.

22 According to a sixth aspect of the invention there is 23 provided a downhole assembly comprising: 24 a tubular main body; at least one recess formed in an outer surface of the 26 body; 27 a removable tool element; 28 wherein the body is provided with at least one bore for 29 coupling the removable tool element to the body, and the bore is aligned on an attachment axis inclined with 31 respect to a radial axis of the body.

1 According to a seventh aspect of the invention there is 2 provided a downhole assembly comprising: 3 a tubular main body; 4 at least one longitudinal recess formed in an outer surface of the body; 6 a removable tool element received in the recess and 7 upstanding from the outer surface of the main body; 8 wherein the removable tool element has an outer surface 9 comprising an upper portion and a side wall portion, and the removable tool element is attached to the main body 11 via a bore extending from the side wall portion, through 12 the removable tool element, and into the main body.

14 Preferably, the bore is aligned on an attachment axis inclined to a radial axis of the tubular body.

17 Preferably, the tubular body of any of the first to 18 seventh aspects of the invention is provided with a 19 plurality of elongate ribs upstanding from an outer surface of the main body and extending at least part way 21 along a length thereof. More preferably, the recess is 22 formed in an outer surface of the rib.

24 The recess may be aligned with the longitudinal axis of the tubular body.

27 Preferably also, adjacent pairs of ribs defining a flow 28 channel therebetween for flow of a downhole medium along 29 the body. The ribs may be aligned substantially parallel S..

to a longitudinal axis of the body. Advantageously, the 31 ribs are shaped such that at least one dimension of each 32 channel is non-uniform.

1 The tubular body may further comprise at least one flow 2 guide located adjacent an end of the channel, the flow 3 guide and the channel together defining a flow path for 4 flow of a downhole medium along the body.

6 According to an eigth aspect of the invention, there is 7 provided a downhole tool comprising: a tubular main body 8 having at least one recess formed in an outer surface of 9 the body, the recess adapted to receive, when the apparatus is in a first configuration, a stabiliser blade 11 of a first radial dimension, and is adapted to receive, 12 when the apparatus is in a second configuration, a 13 stabiliser blade of a second radial dimension.

According to a ninth aspect of the invention there is 16 provided downhole apparatus comprising: 17 a tubular main body; 18 a plurality of elongate ribs upstanding from an outer 19 surface of the main body and extending at least part way along a length thereof, adjacent pairs of ribs defining a 21 flow channel therebetween for flow of a downhole medium 22 along the body; 23 wherein at least one rib is provided with a longitudinal 24 recess formed in an outer surface of the body, the recess adapted to receive a removable tool element.

27 Preferably, the ribs are aligned substantially parallel 28 to a longitudinal axis of the body. More preferably, 29 the ribs are shaped such that at least one dimension of S. each channel is non-uniform. 31 **

32 According to a tenth aspect of the invention, there is 33 provided a multi-function downhole apparatus comprising: 1 a tubular main body having at least one recess formed in 2 an outer surface of the body, the recess adapted to 3 receive, when the apparatus is in a drilling 4 configuration, a first interchangeable tool element for use in a drilling operation, and is adapted to receive, 6 when the apparatus is in a wellbore clean-up 7 configuration, a second interchangeable tool element for 8 use in a welibore clean up operation.

It will be appreciated that the apparatus of all aspects 11 of the invention may be provided as an integral part of 12 the tool or tubing string, or as a separate component 13 adapted to be coupled to tubing, a tool string or 14 sections of a tubing string such as a length of casing.

In particular, the apparatus may be formed as an integral 16 part of a tool string component, and may indeed form an 17 integral part of a drill pipe section.

19 There will now be described, by way of example only, embodiments of the present invention with reference to 21 the following drawings, of which: 23 Figure lA is a perspective view of apparatus in 24 accordance with a first embodiment of the invention; *e.e

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26 Figures lB and lC are respectively side and plan 27 views of the apparatus of Figure lA; 29 Figure 2A is a perspective, partially exploded view of a stabiliser assembly consisting of the apparatus 31 of Figure 1 and removable stabiliser blades; 1 Figures 2B and 2C are respectively side and plan 2 views of the assembly of Figure 2A; 4 Figure 3 is a perspective view of a cleaning assembly consisting of the apparatus of Figure 1 and 6 removable cleaning brushes; 8 Figure 4 is a perspective view of a cleaning 9 assembly consisting of the apparatus of Figure 1 and removable brush scrapers; 12 Figure 5 is a perspective view of an assembly 13 consisting of the apparatus of Figure 1 and flush 14 tool elements; 16 Figure 6 is plan view of a recess of the apparatus 17 of Figure 1; 19 Figure 7 is a cross-sectional view of an embodiment of the invention showing recess profile and an 21 attachment arrangement for removable tool elements; 23 Figure 8A is a perspective view of a further 24 embodiment of the invention having a set of recesses run in tandem; 27 Figure 8B is a circumferential detail of a further 28 embodiment of the invention; and

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Figure 9 is a perspective view of a further 31 embodiment of the invention, configured as a hole 32 opening tool.

1 Reference is made firstly to Figures 1A, lB and 1C, in 2 which downhole apparatus in accordance with a first 3 embodiment of the invention is shown, generally depicted 4 at 10. As will be described in more detail below, the downhole apparatus 10 may take the form of one of a 6 number of different types of downhole tools or equipment.

7 However, in general terms, the downhole apparatus 10 8 comprises a tubular main body 12; at least one flow 9 channel 14 extending part-way along a length of the body 12 and a plurality of raised portions or ribs 15 formed 11 on the body 12. The ribs 15 are shaped such that a 12 dimension of the channel 14 (in this case, width) is non- 13 uniform. Flow guides 16 located adjacent to an end 18 of 14 the channel 14, the flow guide 16 and the channel 14 together defining a flow path for flow of a downhole 16 medium along the body 12.

18 The apparatus 10 serves for promoting improved fluid flow 19 along an annulus defined between the body 12 and the wall of a well borehole or of a tubing in which the apparatus 21 is located. It will therefore be understood that the 22 apparatus 10 may be located in open hole, that is within 23 a drilled borehole of an oil or gas well; within tubing 24 previously located in a borehole such as a casing or liner; or indeed within other tubing such as a tool 26 string. The apparatus 10 therefore has a wide range of 27 potential uses in the downhole environment. : 28 ** 29 The apparatus 10 is configured to as a tool for connection to, or incorporation into, a string of tubular 31 members employed in wellbores. The body 12 of the 32 apparatus 10 can be located in a weilbore with its 1 longitudinal axis aligned with the longitudinal axis of 2 the welibore.

4 The ribs 15 are arranged to define a specific flow path such that a channel is formed between the edges of the 6 pads 15. The channel has varying width due to the 7 curvature of the edges of the pads 15. The flow guides 8 16 may be provided with cutting edges l7A, l7B f or 9 disturbing the flow or breaking up particles and material such as debris and cuttings that may be present in the 11 borehole fluid flow.

13 The ribs 15 are distributed circumferentially around the 14 tubular body 12 with their longitudinal axes aligned with the longitudinal axis of the tubular body 12. In this 16 embodiment three ribs are distributed with equal spacing 17 around the circumference of the tubular body 12. The 18 spacing and longitudinal dimension of the ribs 16 is 19 sufficient for imparting a directional effect on fluid flowing past.

22 Each rib 16 is provided with longitudinally aligned 23 recesses 11 into which different tool elements may be 24 received and coupled to the tubular body 12. The recesses 11 comprise a substantially rectangular milled recess 26 formed in the pad surfaces 19 of the ribs 15. In other 27 embodiments the recesses 11 may have a different shape.

28 The recesses are dimensioned such that a tool element 29 located into the recess fits snugly with minimal relative motion between the tool element and the juxtaposing 31 interior side wall surfaces of the recesses 11.

1 The ribs are shaped so that the basic tubular body 2 provides the aforementioned benefits in affecting flow of 3 fluid and cuttings, whilst providing an appropriate 4 surface area for recesses accommodating a plurality of interchangeable tool elements. The recesses are designed 6 to receive a plurality of different tool elements having 7 different functions and/or different dimensions to permit 8 the same tool body to be used in a number of different 9 weilbore operations. In this fashion, the apparatus 10 provides the basis for a variety of tool assemblies 11 including stabilising, reaming and cleaning tools.

13 Figures 2A to 2C show the apparatus of Figure 1 14 configured as a stabiliser assembly, for use, for example, on heavyweight drill pipe.

17 The assembly, generally depicted at 100, consists of the 18 apparatus 10 and a plurality of removable tool elements, 19 which in this example are stabiliser blades 102. The blades 102 are dimensioned to fit exactly within the 21 longitudinal recesses 11. Attachment means are provided 22 for removable attachment of the blades 102 to the 23 apparatus 10. *

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The blades 102 are formed to a specific (radial) depth to 26 provide stand-off between the inside wall of a wellbore 27 and the tubular member 3. The depth, and thus the outer 28 diameter of the assembly, is chosen according to the 29 inner diameter of the borehole or casing in which the I...

string is being run, in order to provide a snug fit. It 31 will be appreciated that a variety of depths of 32 stabiliser blades can be made available at the surface to 1 allow the basic apparatus 10 to be configured for a range 2 of different borehole diameters.

4 Figure 3 shows the apparatus 10 configured as a cleaning tool, for use, for example, in cleaning the inner surface 6 of casing in a wellbore. The assembly, generally 7 depicted at 110 consists of the apparatus 10 and a 8 plurality of removable tool elements, which in this 9 example are wire brush assemblies 112. The brush assemblies 112 consist of brush housings 114 dimensioned 11 to fit exactly within the longitudinal recesses 11 and an 12 arrangement of wire bristles 116 on the exterior surface 13 of the brush assembly. Attachment means are provided for 14 removable attachment of the brush assemblies 112 to the apparatus 10.

17 It will be understood that a variety of depths of brush 18 assemblies and bristle arrangements can be made available 19 at the surface to allow the basic apparatus 10 to be configured for a range of different borehole diameters.

22 Figure 4 shows the apparatus 10 configured as part of a 23 scraping tool, for use, for example, in scraping the 24 inner surface of casing in a wellbore. In this embodiment, the assembly, generally depicted at 120 26 consists of the apparatus 10 and a plurality of removable 27 tool elements, which in this example are brush scraper 28 assemblies 122. The brush assemblies 122 consist of 29 housings 124 dimensioned to fit exactly within the S..

longitudinal recesses 11 and an arrangement of scraping 31 bristles 126 on the exterior surface of the scraper 32 assembly. Attachment means are provided for removable 1 attachment of the brush assemblies 122 to the apparatus 2 10.

4 The arrangement of Figure 4 is similar to the arrangement shown in Figure 3, although the depth of the housings is 6 selected to be substantially flush with the ribs 15, such 7 that only the bristles protrude from the outer surface of 8 the ribs.

It will be understood that a number of different tool 11 elements having scraper blades, bristles or pads could be 12 provided for a variety of cleaning operations.

14 Figure 5 shows the apparatus 10 in an alternative configuration, generally depicted at 130, in which the 16 recesses 11 are provided with inserts flush to the outer 17 surface of the ribs 15. In this embodiment, the tool may 18 be run in welibore of diameter substantially equal to the 19 outer diameter of the ribs 15 and the flow guides 16 and perform a number of different stabilising, centralising, 21 reaming, cleaning or scraping functions.

23 The arrangement of the leading set of flow guides 16, the 24 various channels 14 defined by the ribs 15, and the trailing set of flow guides 16 define a number of flow 26 paths for flow of fluid across the main body 12 of the 27 apparatus 10. These various flow paths provide an 28 efficient mixing of constituents of the downhole medium, 29 preventing blockage of the flow paths and in particular of the channels 14, in use.

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32 The apparatus 10 additionally defines a number of cutting 33 or abrading surfaces, for reaming a borehole, or for 1 cleaning an inner surface of tubing in which the 2 apparatus is located. In more detail, the end of each 3 flow guide 16 typically forms a relatively aggressive 4 cleaning blade or scraper for reaming/cleaning during passage of the apparatus downhole. In a similar fashion, 6 the end of each trailing flow guide 16 defines less 7 aggressive blades or scrapers, to provide a 8 reaming/cleaning function when the apparatus is 9 translated uphole. Also, each of the ends of the guides 16 and the edges of the ribs 15 may define blades or 11 scrapers, for providing a rotary reaming/cleaning 12 function. Furthermore, radially outer surfaces of the 13 apparatus 10, such as outer surfaces of the ribs 15 and 14 guides 16 may define or include abrasive particles, and may, for example, be coated with Tungsten-Carbide grit.

17 Particular applications for which flush inserts are 18 provided include applications when the apparatus is used 19 as a sleeve or housing for a downhole tool such as a downhole motor, and serves to centralise or support the 21 tool within a bore hole or existing tubing.

23 Flush inserts may also be used where the apparatus forms 24 part of a casing shoe or a drill shoe. The apparatus may for example for part of a casing shoe reamer which 26 assists the passage of a casing string into a drilled 27 welibore. * 29 There now follows a description of the details of the attachment between the main body of the apparatus and the 31 tool elements. * c. C,.. * * S

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1 Figure 6 is a plan view of a recess 11 formed in a rib 15 2 on a tubular body 12. Figure 7 shows a cross section 3 through a different tubular body 12' having three 4 recesses 11' formed therein. Although the embodiment of Figure 3 lacks the ribs of the embodiment of Figure 2, 6 the shape and form of the recesses 11' and the attachment 7 means are identical to recesses 11.

9 The recesses 11, 11' comprise a base surface having a first portion 21 formed to a specified depth below the 11 outer surface of the body 12. The first portion 21 12 extends along the entire length of the longitudinal 13recesses 11, 11', and the surface of the first portion 14 lies in a plane substantially aligned perpendicular to the normal axis of the body 12. That is, the first 16 portion 21 forms the base of a square section recess.

18 The recesses 11, 11' also comprise a second portion 22 19 extending along the entire length of the longitudinal recess 11, and forming the junction between the first 21 portion 21 and a side wall 24 of the recess. The surface 22 of the second portion lies in a plane inclined with 23 respect to the first portion 21 and the side wall 24, and 24 the second portion 22 therefore forms a surface inclined to the normal axis of the body.

27 The first and second portions 21, 22 of the base surface *..: 28 are provided with threaded bores 31, 32 and 33 for 29 receiving screws for attachment of tool elements. Bores 31 are provided in the first portion 21 along a central 31 longitudinal axis of the recess. The bores 31 are 32 substantially radially aligned, to receive a screw 1 aligned on the normal axis of the main body 12, through a 2 corresponding bore in the removable tool element.

4 Bores 33 are provided close to the corners of the recess 11, and are similarly radially aligned to receive screws 6 aligned on the normal axis of the main body 12, through 7 corresponding bores in the tool elements. This 8 attachment arrangement is suitable for attaching, for 9 example, the brush assemblies as shown in Figure 3.

11 Bores 32 are provided in the second portion 22, and are 12 aligned normally to the inclined surface of the second 13 portion, as most clearly shown in Figure 6.

In the arrangement of Figure 6, tool elements 34 have a 16 cross-sectional profile to fit with the cross-sectional 17 profile of the recess 11'. In this example, one edge of 18 the tool element 34 is provided with a shoulder 35 which 19 abuts the outer surface of the body 12' along the edge of the recess 11'.

22 The tool element 34 has a prismatic profile that is 23 formed to fit closely into the recess 11'. The depth of 24 the pocket 11 and thickness of the tool element is sufficient that displacement by tangential or 26 longitudinal forces is limited or avoided. SI.

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28 The tool elements 34 are secured to the tubular body 12' 29 by means of screws (not shown) that are provided through a securing bore 36 in the tool element 34. The bore 36 31 extends from a scalloped opening 38 provided in an edge 32 39 of the tool element 34. The holes 36 align with 33 threaded holes 32 in the body 12' in the angular surface 1 22 of the recess 11'. The threaded holes 32 engage and 2 secure to a mating thread at the end of the screw. The 3 head of the screw abuts against an abutting surface in 4 the opening 38.

6 In this embodiment, the positioning of the bore opening 7 38 and the screw head at a side of the tool element 34 8 prevents interference with the operational part of the 9 tool element. Further, the attachment arrangement is such that upon clockwise rotation of the tool in the 11 welibore, forces imparted on the tool element 34 by the 12 welibore walls will tend to be directed axially along the 13 longitudinal axis of the screws and will therefore tend 14 to prevent the screw from being subjected to non co-axial stresses and strains.

17 The attachment arrangement of Figure 7 provides 18 additional advantages in relation to tool elements with a 19 large depth or radial dimension, such as stabiliser blades. If a stabiliser blade is required to give 6" 21 (15cm) stand-off between a weilbore wall and the main 22 body of the tool, a screw normally aligned through the 23 tool element may be required to be up to 12" (30cm) so 24 that it can extend through the full depth of the stabiliser blade and into the body 12'. By providing an 26 inclined bore and screw, the length of the blade can be 27 reduced. In addition, the same length of screw could be *: 28 used for all sizes of stabiliser blade.

The apparatus also provides threaded bores 31, 33 (not 31 shown in Figure 7 for clarity reasons) for attachment of 32 other tool elements with different locations of securing 33 holes. For example, threaded bores 33 may be used in an 1 alternative embodiment where the tool elements to be 2 located in the recesses 11, 11' have securing holes in 3 corresponding corners. This functionality provides for 4 attaching tools by the method most suited to their performance.

7 It will be appreciated that the attachment arrangement of 8 Figure 7 may be applied to other recess and tool element 9 configurations in addition to any of the embodiments described hereto. It will also be appreciated that 11 although the described embodiments have an inclined bore 12 32 at approximately 45 degrees to the normal axis of the 13 body 12, other angles of inclination may be used.

14 Additionally, in alternative embodiments the inclined surface profile may differ, and include additional 16 portions with different angles of inclination, or indeed 17 curved portions. Although it is preferred that the 18 surface profile includes at least one angled or curved 19 portion, it is not an essential part of the invention.

It will be understood that an inclined axis for the 21 attachment means provides the benefits and advantages 22 described above.

24 Figures 8A and SB show a further embodiment of the invention configured as a magnetic junk recovery tool, 26 generally depicted at 140. In this embodiment, the tool 27 comprises a tubular body having male and female rotary 28 shouldered connection 142a and l42b at first and second 29 ends respectively. In this embodiment, the tool comprises two sets of ribs l5a and 15b, having 31 respectively two sets of recesses lla and llb. One set 32 of hex pads 144 are located in between sets of ribs and 33 recesses. The tool 140 can therefore be considered as a 1 pair of tools 10 of Figure 1 run in tandem. As before, 2 the tool is provided with leading and trailing flow guide 3 146.

As in the embodiment of Figure 1, each set of ribs 15 6 comprises three ribs circumferentially displaced at 120 7 degrees. However, the blades 15b are rotationally off- 8 set with respect to blades 15a by 60 degrees. This 9 causes the ribs 15b to be aligned with the flow path defined by ribs l5a. The provision of the two sets of 11 recesses rotationally off-set provides maximum 12 circumferential coverage when running the tool in the 13 wellbore.

The recesses lla and llb are provided with magnetic 16 inserts 148. These magnetic inserts are countersunk into 17 the recesses to provide a pocket for containing ferrous 18 debris, junk and cuttings from the welibore.

A variety of magnetic inserts could be used. For 21 example, the recess could be provided with a metallic 22 plate, which on its lower side is provided with recesses 23 to accommodate a number of magnets to be retained beneath 24 the plate.

26 In the embodiments shown, the ribs 15 are formed to the 27 same height as the flow guides 146, which are gauge with 28 the casing in which the tool is run. However, in 29 alternative embodiments, the radial height of the ribs 15 could be lower than that of the flow guides 146. This 31 may improve the ability of the tool to collect debris and S...

32 junk from the weilbore. *:::: 1 It will be appreciated that the tandem design shown in 2 Figures 8A and 8B could be adopted for alternative 3 operational configurations. For example, the cleaning 4 tools of Figures 3 and 4 could comprise a tandem configuration, with one set of cleaning tool elements 6 rotationally off-set with respect to the other. This 7 would provide increased circumferential coverage of the 8 cleaning tool when being run in the welibore.

It should be noted that Figure 8B is a circumferential 11 view of a tool configuration very similar to that of 12 Figure 8A, although the shape of the intermediate pads 13 144' is different.

Figure 9 illustrates a further embodiment of the 16 invention, in which the tool body of Figure 1 receives a 17 hole opener tool element 152 to provide a hole opener 18 tool, generally shown at 150.

The hole opening tool element comprises a support member 21 152 shaped to be received in the recess 11, and which 22 extends radially from the tool body. The support member 23 152 is provided with a leading face 154 which is inclined 24 towards the tubular body. The face 154 provides a bearing surface for a rotary cutter blade 156, which is 26 mounted rotationally via a bore 158 extending through the 27 support member 152. When assembled, the rotary cutter 28 member 156 is aligned in the space defined by the flow 29 guide members 16. The rotary cutting member 156 does not contact the tubular body, and is free to rotate about the 31 axis defined by the bore 158. When assembled, the hole 32 opener tool consists of three support members 152 and 33 cutting members 156, one for each of the recesses 11.

2 The tool 150 may be part of kit of parts comprising a 3 plurality of tool elements including hole opener tool 4 elements. Hole opener tool elements of different radial dimensions may be provided, such that tool elements are 6 available to increase the diameter of a well bore to a 7 specific size. The tool may also be configured in 8 tandem, such that a hole opener tool of a first bit size, 9 for example 17" inches (445 millimetres) is provided below a second hole opener tool having bit size of 26 11 inches (660 millimetres) 13 In this embodiment, the tool is also provided with 14 jetting port 160 located in the outer surface of the flow guide 16. The jetting port provides a flow path from the 16 internal bore of the tool to the exterior of the tool.

17 The jetting port 160 is configured to direct a fluid 18 towards the rotary cutters 156 to remove cuttings from 19 the cutting blades.

21 It should be appreciated that tool elements for carrying 22 out operations other than those described above could 23 also be employed by attaching them into pockets in a 24 manner similar to the tool elements of the previously described embodiments. For example, the recess may 26 receive a roller reamer tool element.

28 It will be understood that in certain embodiments, the 29 shape and configuration of the ribs may vary. For example, the ribs may be helically oriented.

32 The multi-functional downhole tool as described in the 33 above embodiments provides a number of advantages. The 1 ribs 15 allow brushes, scrapers, blades or other tool 2 elements to be attached and engage with the welibore over 3 the length of the ribs. Tool elements with relatively 4 large surface and operational area may therefore be employed whilst fluid flow is spatially well- 6 accommodated.

8 In addition, the provision of ribs 15 to create a channel 9 15 in the tool portion 5 and perturbations imparted on the fluid flow improves the efficiency of removing 11 material and flow fluid away from and past the downhole 12 tool during operation, particularly in a mode of 13 operation where the tool is run with minimal stand-off.

14 Further, flow guides 16 assist in the above flow by breaking down globules of particles or other material 16 that may be present in the fluid.

18 Another advantage is that the tool minimises costs 19 arising from operational wear as it is only necessary to change out and replace the particular elements that are 21 worn. Further, the simple attacbment arrangement 22 promotes easy handling and replacement in the field and 23 is relatively quick to replace. Furthermore, the 24 flexibility of using a generic tubular member can reduce the initial capital expenditure that would otherwise be 26 required when using separate tools for different 27 purposes. * 29 The present invention provides an improved system for performing a number of downhole functions whilst 31 efficiently removing borehole fluid, particles and debris *s.e.

32 from a well bore.

1 In use, the multi-functional downhole tool is typically 2 attached as part of a drill string upon which torque is 3 imparted during drilling of a well. The tool allows 4 removable attachment of different tool elements for performing various functions during rotary drilling and 6 upon insertion and extraction of the drill string from 7 the well. Tool elements such as brushes or scrapers or 8 wipers are screwed into pockets provided in pads located 9 on the downhole tool by securing them to. This may be necessary for commencing new operations or to replace 11 worn tool elements.

13 Whilst the string containing the tool is located in the 14 well bore, functions such as cleaning, scraping or stabilising of the welibore may be carried out whilst 16 rotary drilling is taking place. As drilling is 17 progressing, drill fluid is pumped through the central 18 annulus of the tool string and returned up through the 19 annulus of the weilbore created between the string and the welibore wall. Flow guides and tool elements 21 provided on the tubular channel the flow of fluid up 22 through the annular space. The flow guides help to break 23 up material located in the flow preventing the tools from 24 clogging and enhancing performance.

26 Various modifications and improvements may be made within 27 the scope of the invention herein described. * * S S S. 55 S... 5*** * . .

S

Claims (1)

1 Claims 3 1. A multi-function downhole apparatus comprising: a 4 tubular

main body having at least one recess formed in an outer surface of the body, the recess adapted 6 to receive each of a set of interchangeable tool 7 elements, wherein the set of interchangeable tool 8 elements comprises any two of a first stabiliser 9 blade, a second stabiliser blade, a cleaning element, a roller reaming tool element, a hole 11 opener tool element, and a drilling casing shoe 12 element.

14 2. The apparatus as claimed in Claim 1 wherein the recess is adapted to receive a first stabiliser 16 blade of a first radial dimension to provide 17 stabilising apparatus for use in a wellbore of a 18 first dimension, and a second stabiliser blade of a 19 second radial dimension to provide stabilising apparatus for use in a wellbore of a second 21 dimension.

23 3. The apparatus as claimed in Claim 2 wherein the 24 recess is adapted to receive a first stabiliser blade to provide stabilising apparatus for a first 26 wellbore dimension, and a cleaning element to 27 provide a wellbore clean-up apparatus. . : 29 4. The apparatus as claimed in any of Claims 1 to 3 * wherein the body is provided with a bore aligned on 31 an attachment axis inclined to a radial axis of the * * 32 tubular body.

1 5. The apparatus as claimed in any preceding claim, 2 comprising a first set of recesses circumferentially 3 distributed around the body.

6. The apparatus as claimed in claim 5, further 6 comprising a second set of recesses 7 circumferentially distributed around the body in a 8 location longitudinally displaced from the first set 9 of recesses.

11 7. The apparatus as claimed in claim 5, wherein the 12 second set of recesses is rotationally offset with 13 respect to the first set of recesses.

8. A downhole apparatus comprising: 16 a tubular main body; 17 at least one longitudinal recess formed in an outer 18 surface of the body; 19 a removable tool element received in the recess and upstanding from the outer surface of the main body; 21 wherein the removable tool element has an outer 22 surface comprising an upper portion and a side wall 23 portion, and the removable tool element is attached 24 to the main body via an attachment mechanism extending from the side wall portion, through the 26 removable tool element, and into the main body. e. 27 *

28 9. The apparatus as claimed in Claim 8 wherein the 29 attachment mechanism comprises a bore aligned on an * * S S attachment axis inclined to a radial axis of the 31 tubular body. s... S...

32.5** 1 10. The apparatus as claimed in any preceding claim 2 wherein the tubular body of is provided with a 3 plurality of elongate ribs upstanding from an outer 4 surface of the main body and extending at least part way along a length thereof.

7 11. The apparatus as claimed in Claim 10 wherein the 8 recess is formed in an outer surface of the rib.

12. The apparatus as claimed in Claim 11 wherein 11 adjacent pairs of ribs define a flow channel 12 therebetween for flow of a downhole medium along the 13 body.

13. The apparatus as claimed in any of Claims 10 to 12 16 wherein the ribs are aligned substantially parallel 17 to a longitudinal axis of the body.

19 14. The apparatus as claimed in any of Claims 10 to 13 wherein the ribs are shaped such that at least one 21 dimension of each channel is non-uniform.

23 15. The apparatus as claimed in any of Claims 12 to 14 24 wherein the tubular body further comprises at least one flow guide located adjacent an end of the 26 channel, the flow guide and the channel together 27 defining a flow path for flow of a downhole medium 28 along the body.

16. A kit of parts for the assembly of a downhole tool, 31 the kit of parts comprising: a tubular main body *IS.

32 having at least one recess formed in an outer 33 surface of the body; and a set of interchangeable 1 tool elements comprising any two of a first 2 stabiliser blade, a second stabiliser blade, a 3 cleaning element, a magnetic debris collector, a 4 roller reaming tool element, a hole opener tool element, a drilling casing shoe element; wherein the 6 recess is adapted to receive one of the set of 7 interchangeable tool elements, to provide a downhole 8 tool having a first operating configuration, and is 9 adapted to receive another of the set of interchangeable tool elements, to provide a downhole 11 tool having a second operating configuration.

13 17. The kit of parts as claimed in Claim 16 wherein the 14 first operating configuration is for a drilling operation, and the second operating configuration is 16 for a weilbore clean up operation.

18 18. A method of configuring a multi-function downhole 19 apparatus, the method comprising the steps of: - Removing a first tool element from a recess in a 21 tubular body; 22 - Removably attaching a second tool element, 23 different from the first, to the recess in the 24 tubular body; Wherein the first and second tool elements are any 26 two selected from a first stabiliser blade, a second 27 stabiliser blade, a cleaning element, a magnetic 28 debris collector, a roller reaming tool element, a 29 hole opener tool element, a drilling casing shoe * : element.

32 19. A method of configuring a downhole apparatus, the::,* 33 method comprising the steps of: 1 - Removing a first tool element from a recess in a 2 tubular body; 3 - Removably attaching a second tool element to the 4 recess in the tubular body; Wherein the first tool element is a stabiliser blade 6 having a first radial dimension for running in a 7 wellbore of first inner diameter, and the second 8 tool element is a stabiliser blade having a second 9 radial dimension, different from the first, for running in a welibore of second inner diameter. * d I$t.I 0,'. * 0 * S * OS S... * 0 *55 S I.,'

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