WO2014167315A2

WO2014167315A2 - Apparatus and method for cleaning a well bore tubular

Info

Publication number: WO2014167315A2
Application number: PCT/GB2014/051095
Authority: WO
Inventors: Ronald Potter
Original assignee: Field Marshall Oil And Gas Technologies Limited
Priority date: 2013-04-10
Filing date: 2014-04-09
Publication date: 2014-10-16
Also published as: GB2499953B; WO2014167315A3; GB201310839D0; GB201306495D0; GB2499953A

Abstract

Apparatus and a method for cleaning the inner surface of a well bore tubular comprises a body having an axis and an axial bore through the body, suitable for connection into a tool string for use in a well bore tubular, and a cleaning device, a stabiliser and typically a junk catcher arranged on the outer surface of the body. The stabiliser is adapted to resist radial compression and is rotatably mounted on the body. The stabiliser is rotationally mounted on bearings on the body. The stabiliser has an arrangement of blades that extend outwardly from the body. The stabiliser can typically have at least one magnetic device to attract and retain ferrous metal particles.

Description

Title: APPARATUS AND METHOD FOR CLEANING A WELL BORE TUBULAR

The present invention relates to a cleaning apparatus for cleaning the inner surface of a well bore tubular, and to a method of cleaning a well bore tubular. Background to the Invention

Earlier designs of cleaning apparatus such as are shown in our earlier patents GB2299599 and GB2447349 (incorporated herein by reference) incorporate cleaning devices such as pads and scrapers on the outer surface of tubular bodies, and stabilisers.

Summary of the Invention

According to the present invention there is provided apparatus for cleaning the inner surface of a well bore tubular, the apparatus comprising: a body having an axis and an axial bore through the body, suitable for connection into a tool string for use in a well bore tubular, a cleaning device mounted on the outer surface of the body for engaging the inner surface of the well bore tubular, a stabiliser arranged on the outer surface of the body and protruding radially outwards from the body towards the inner surface of the well bore tubular, wherein the stabiliser is adapted to resist radial compression and thereby maintain a constant radial separation between the body and a radially outer surface of the stabiliser, wherein the stabiliser is rotatably mounted on the body.

In certain examples, the apparatus optionally incorporates a junk catcher, comprising a junk-receiving chamber with an opening at one end of the chamber, adapted to receive particulate matter suspended in fluid in the annulus between the body and the well bore tubular. Optionally the junk catcher is arranged to agitate the contents of the chamber by the relative rotation of portions of the chamber.

The invention also provides a method of cleaning the inner surface of a well bore tubular, the method comprising: providing a cleaning apparatus comprising a body having an axis and an axial bore through the body, mounting a cleaning device on the outer surface of the body, rotatably mounting a stabiliser arranged on the outer surface of the body and protruding radially outwards from the body, wherein the stabiliser is adapted to resist radial compression, connecting the apparatus into a tool string and running the tool string into the well bore tubular, and engaging the outer surface of the stabiliser against the inner surface of the wellbore tubular, maintaining a constant radial separation between the outer surface of the body and the outer diameter of the non-radially compressible stabiliser, and rotating the body with respect to the stabiliser as the stabiliser remains stationary relative to the wellbore tubular to rotate the cleaning devices against the inner surface of the wellbore tubular.

In certain examples, a junk catcher is optionally provided on the body comprising a chamber to receive particulate matter suspended in fluid in the annulus between the body and the well bore tubular, wherein at least a part of the junk catcher is rotationally connected with at least one stabiliser and rotates relative to the body with the stabiliser, and the method optionally includes rotating a first portion of the junk catcher relative to a second portion of the junk catcher.

The invention also provides a junk basket assembly for incorporating in a work string for removing particulate materials from a well bore tubular, the apparatus comprising: a body having an axis and an axial bore through the body, suitable for connection into a tool string for use in a well bore tubular, a chamber for receiving particulate matter suspended in fluid in the wellbore, the chamber comprising an outer wall and an inner wall radially inside the outer wall, a stabiliser protruding radially outwards from the outer surface of the body towards the inner surface of the well bore tubular, wherein the stabiliser is adapted to resist radial compression and thereby maintain a constant radial separation between the body and a radially outer surface of the stabiliser, wherein the stabiliser is rotatably mounted on the body; wherein the outer wall of the chamber is non-rotatably connected with the stabiliser and the inner wall of the chamber is non-rotatably connected with the body, wherein rotation of the body relative to the stabiliser rotates one of the inner and outer walls of the chamber relative to the other. Typically the junk basket assembly has an impeller device arranged to generate thrust in the chamber. Typically the impeller device is non-rotatably connected with the body, so that rotation of the body rotates the impeller device. Typically the impeller device is disposed within the chamber. Typically the impeller device is secured on the outer surface of the body, typically on the inner wall of the chamber. Typically the impeller device has at least one blade. Typically the blade can have the form of a foil, typically having a concave lower face and a convex upper face, and typically having a leading edge (in the direction of rotation of the impeller device) that is disposed above a trailing edge of the blade. Typically the impeller device has more than one blade, and typically the blades are arranged symmetrically around the circumference of the body, typically spaced at substantially regular intervals around the circumference of the impeller device, typically in the same orientation around the outer circumference of the body. Accordingly, as the body rotates in a clockwise direction as viewed from the top of the work string, the blades rotate with the body with a leading edge higher than a trailing edge. Therefore, the rotation of the blades typically generates downward thrust in the fluids in the chamber, urging particular matter suspended within the fluid in the chamber towards the bottom of the chamber. In addition, fluid outside the chamber can be drawn into the mouth of the chamber by the thrust generated by the impeller.

Typically at least one of the blades has at least one hardened face. The hardened face can be formed by coating the blades with a hardened material, such as a ceramic material. In certain aspects, at least some of the faces of the blades are coated with tungsten carbide. Typically some of the faces of each blade can be coated in a different manner, or with a different material from others. In particular, the radially outermost face of each blade typically has a smoother coating than the upper, lower and front and rear faces of the blade. Typically abrasive action of the blades helps to reduce the particle size of the material collected in the chamber, and ensures a more consistent particle size distribution of the particulate material in the chamber. Optionally the inner walls of the basket can be hardened, typically with a similar coating. Optionally according to the third aspect, the junk basket assembly can incorporate a cleaning device mounted on the outer surface of the body for engaging the inner surface of the well bore tubular. The radially incompressible stabilisers help to maintain a constant standoff (radial separation) between the body (e.g. the cleaning device) and the inner surface of the tubular being cleaned.

Typically at least two stabilisers are provided. The stabilisers can be axially spaced from one another along the apparatus. The apparatus typically comprises a single sub, having box and pin (or other suitable) connections for incorporation into a tool string to be deployed and used in a well bore of an oil or gas (or other) well.

Typically all the components are incorporated on the same sub. Typically the stabiliser is rotationally mounted on bearings, typically spherical ball bearings, although roller or other bearings could also be used. Typically the stabiliser is mounted on at least two bearing races, spaced axially apart along the stabiliser. Typically the bearing races and bearings secure the stabiliser against axial movement along the body. Typically the bearings allow rotational movement but deny axial movement. Typically each the race comprises an inner and an outer cup with a break line that intersects the bearings (typically bisecting the bearings) thereby resisting axial thrust forces applied to the stabiliser, and locking it in a secure axial position on the body. Typically the stabiliser needs no other axial fixing or other anchor to prevent or restrict axial movement and resist axial thrust loads.

Typically, the stabiliser comprises one or more radially projecting blades, which extend outwardly from the outer surface of the body of the stabiliser in a radial direction. Typically at least two blades are provided on each stabiliser, typically spaced circumferentially around the stabiliser with respect to one another, and typically the blades are arranged at the same axial location on the stabiliser to form a row. Typically each row of blades comprises more than two blades, for example 4, 5, 6 or more blades per row. Typically each stabiliser has more than one row of blades, and typically the rows of blades are axially spaced from one another along the stabiliser. Typically the blades in each row are circumferentially staggered with respect to the blades in an adjacent row. Typically the blades in one row are aligned with the channels in an adjacent row, and typically the combined radially outermost surface of the blades on each stabiliser typically extends around substantially the whole circumference of the stabiliser. The blades typically maintain a minimum stand-off (a minimum radial spacing) between the stabiliser and the inner surface of the wellbore tubular. The blades are typically aligned generally with the axis of the body.

Typically the apparatus incorporates at least one magnetic device to attract and optionally retain ferrous metal particles onto the sub, typically on the outer surface of the stabiliser, and typically onto portions of the outer surface of the stabiliser between the blades, for example in the channels, and between rows, or above or below a stabiliser blade array. Typically more than one magnetic device is provided, optionally in the form of a plurality of discs of magnetic material that are received and retained within recesses on the outer surface of the stabiliser body. Optionally, the magnetic devices can incorporate high-strength magnets. Optionally the magnetic devices are arranged in a pattern so that each magnetic device is spaced from other magnetic devices. Typically the pattern is regular, but can be irregular.

Typically the radially outermost surface of the blades sweep circumferentially in arcuate curves around the axis of the body, but are typically flat in a plane parallel to the axis of the body, so that the radially outermost arcuate surfaces of the blades engage with the inner surface of the well bore tubular to be cleaned, allowing axial sliding and circumferential rotational movement of the blades against the inner surface of the tubular to be cleaned. Typically the radially outermost surfaces of the blades have the same radius of curvature around the axis of the body. Typically the axis of curvature is chosen to match that of the inner surface of the tubular. It can optionally be the same as the radius of curvature of the body of the sub. Typically the radially outermost diameter of the outer surface of the blades on each stabiliser is less than the maximum outer diameter of cleaning formations such as scrapers or brushes which extend radially outward from the cleaning devices, but typically greater than all other components of the apparatus, for example greater than the diameter of the body of the cleaning pads supporting the cleaning formations.

Optionally the stabilisers rotate on sealed bearings. Typically the bearings are sealed by annular seals compressed between the stabiliser and the body in an axial position between the bearings and the end of the stabiliser. Two seals are typically provided. The seals typically isolate the bearings from the external environment. The seals can comprise O-ring seals, but other seals (chevron, lip, etc.) can be used.

Typically the cleaning devices have cleaning surfaces that present cleaning formations such as brushes or pads, and typically the cleaning surfaces cover circumferentially spaced apart areas on each cleaning device. Typically the cleaning devices are arranged in axially aligned rows, in a similar manner to the blades on the stabiliser, and typically cleaning devices in different rows are circumferentially staggered, in the same manner as the blades on the stabilisers, so as to cover substantially the whole of the circumference of the body with cleaning surfaces. Typically the cleaning devices are mounted on resilient devices such as springs that are held in compression against the body, so as to urge the cleaning devices radially outward against the inner surface of the well bore tubular being cleaned. Typically the body of the cleaning pads on which the brushes or scrapers etc. are mounted has a smaller outer diameter than the outer diameter of the blades on the stabilisers, so that even when the cleaning devices are urged outward to the maximum extent by the springs compressed between the cleaning device and the body, the body of the cleaning device does not engage the inner surface of the wellbore directly, but instead presses the cleaning formations such as the brushes and scrapers held on outer surface of the body of the cleaning device against the inner surface of the wellbore tubular being cleaned. This reduces wear on body of the cleaning devices, which is spaced from the inner surface of the tubular by the stabiliser. Typically the cleaning devices are fixed to the body of the sub in recesses formed in the outer surface of the sub, and are unable to rotate relative to the body.

Accordingly, torque and axial thrust applied to the body of the sub is typically transmitted efficiently to the cleaning devices, which scrape and/or brush against the inner surface of the wellbore tubular being cleaned, removing debris.

Optionally, the cleaning devices are removable from the body, allowing replacement of the cleaning devices when they are worn. Typically the cleaning devices are restrained against radial movement by restrainers such as annular rings which typically extend over a portion of each cleaning pad, allowing limited radial movement to compress the springs inwardly, but limiting outward radial movement of the cleaning devices beyond the extent permitted by the annular rings. Typically the annular rings, or some of them, are secured to the body by screw threads, allowing removal of the annular rings when the cleaning devices are to be removed for maintenance or replacement.

Typically the junk catcher chamber comprises a blind ended annular or partially annular catching chamber. Typically the junk catcher has drain holes, to allow fluids to escape from the chamber but typically arranged to retain junk and particulate matter within the chamber. In certain examples, the drain holes can be provided at the blind end of the chamber, but in typical examples the drain holes are distributed along the length of the chamber, typically along substantially the whole length of the chamber, and typically in a regular or irregular pattern. Typically the open end of the chamber opposite to the blind end is open to the borehole to receive junk into the chamber. Typically the junk catcher is integral with at least one stabiliser.

Typically the open end of the chamber is oriented toward the top of the well bore (i.e. the surface). Typically the annular chamber is concentric with the axis of the body, but this is not essential, and asymmetric chambers can be used. Typically the open end of the junk catcher chamber has a deflector to deflect junk and particulate matter circulating in the annulus between the body and the casing into the chamber. Typically the deflector can be connected to the outer surface of the junk chamber in a cantilever joint, and the free end of the deflector can extend radially at an angle with respect to the axis of the body, into the annulus. The outer free end of the deflector can optionally be above the cantilever joint, so that the deflector channels junk and particulates above the deflector into the mouth of the chamber. The deflector can optionally be movable between a radially extended position and a radially collapsed position, so that it can change the angle of the joint with the outer surface of the chamber, and fold closer to the body, optionally parallel or closer to parallel to the body in the radially collapsed position than in the radially extended position. Typically the deflector is frusto -conical, with a narrow end and a wide end, and with the narrow end connected to the body at the cantilever joint, and the wider end extending radially outward from the body, and disposed above the narrow end.

Optionally the deflector is resilient; typically the outer free end of the deflector is resiliently energised radially outward. Typically when the device is deployed in a casing, the outer free end of the deflector is resiliently energised radially outward against the inner surface of the casing, to wipe the inner surface and guide the particulate matter in the annulus into the mouth of the chamber, for transport to the surface. Typically the deflector is radially expanded by pulling the body out of the bole. Typically the deflector is radially retracted by pushing the body into the hole. Typically the fluid pressure differential generated in the annulus during axial movement of the body in the casing folds and expands the deflector.

Typically the junk catcher is rotationally connected to one of the stabilisers, and thus rotates relative to the body of the sub with the stabiliser, which typically remains stationary relative to the wellbore being cleaned, as the body of the sub rotates inside it.

Typically the junk catcher is arranged to agitate the chamber, and thereby settle the junk within it, thereby facilitating the accumulation of more junk in the chamber, which is more densely packed as a result, and also resisting migration of the junk out of the chamber, resulting from the denser packing of the junk in the chamber. Accordingly the junk catcher is more efficient as a result of the agitation.

Typically the agitation is provided by the relative rotation of portions of the chamber, typically an inner and outer wall of the chamber. Optionally the outer wall of the chamber is arranged to rotate relative to the inner wall of the chamber.

Typically the incorporation of the sub in a work string can reduce the number of tools currently used in the string, reducing the length, cost and complexity of the string.

Typically the same tool body can be used for a scraper or a brush tool by replacing the inserts. Optionally some of the recesses can incorporate scrapers, and some can incorporate brushes, at either the same or different axially spaced recesses.

Because the stabiliser does not rotate with body during rotation of the string this reduces torque on the string and reduces wear on the casing in which the string is deployed. The stabiliser can also be used to check the drift size of the casing while cleaning. The stabiliser assists in centralising the tool in the well bore, allowing the tool to clean around 360 degrees of the inner surface of the tubular. The sub is typically easily assembled and locked together solely by the bearings which can avoid or reduce the need for bolts, nuts and other similar fixings, which reduces failure due to loosening of fixings. The bearings are retained internally in the stabiliser, and cannot escape, thereby reducing risks of dropped objects in the well. As the sub typically combines several functions (magnets, scrapers, brushes, junk catcher, stabiliser) the operator can optionally reduce the number of subs in the string, saving time and costs with fewer joints to make up during running into the hole, and fewer joints to break during pulling out of the hole. The pads are typically formed with lips to engage a counter bore of the retaining rings, which typically allows the pads a range of free radial movement within the limits of the counter bore while under compression in the tubular. The resilient springs press the pads against the inner wall of the tubular during cleaning operations, and at the same time compensate for radial dimensional changes due to wear of the brushes or scraper formations.

The various aspects of the present invention can be practiced alone or in

combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one example can typically be combined alone or together with other features in different examples of the invention.

Various examples and aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrate a number of exemplary aspects and implementations. The invention is also capable of other and different aspects and implementations, and its several details can be modified in various respects, all without departing from the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive.

Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or

"containing" for applicable legal purposes.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially of", "consisting", "selected from the group of consisting of", "including", or "is" preceding the recitation of the composition, element or group of elements and vice versa.

All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa. References to positional descriptions such as upper and lower and directions such as "up", "down" etc. in relation to the well are to be interpreted by a skilled reader in the context of the examples described and are not to be interpreted as limiting the invention to the literal interpretation of the term, but instead should be as understood by the skilled addressee, particularly noting that "up" with reference to a well refers to a direction towards the surface, and "down" refers to a direction deeper into the well, and includes the typical situation where a rig is above a wellhead, and the well extends down from the wellhead into the formation, but also horizontal wells where the formation may not necessarily be below the wellhead.

Brief description of the Drawings

In the accompanying drawings,

Figure 1 is a side view of a sub;

Figs 2 to 9 show section views through the sub of fig 1 through section lines A-A to G-G depicted in Fig 1;

Fig 10 shows a longitudinal section view through the fig 1 sub;

Figure 11 is a side view of a second sub;

Figs 12 to 20 show section views through the sub of fig 1 through section lines A-A to J-J depicted in Fig 11; and Fig 21 shows a longitudinal section view through the fig 1 sub.

Detailed description of one or more examples of the Invention

Referring now to the drawings, a sub 1 is shown suitable for incorporation into a work or drill string for deployment in an oil or gas well, and has, for this purpose, box and pin connections at opposite ends. Typically the box connection is provided at its upper end, which in this case is shown on the right hand side of fig 1, and the pin connection is provided at its lower end, at the left-hand side of fig 1. The skilled person will appreciate that different connections can be used, and the terms upper and lower, and similar terms reflecting the orientation of the sub in a wellbore, are used to indicate the proximity of each component being discussed in relation to the wellhead at the surface of the well, and that in practice, in certain deviated and horizontal well bores, what is referred to as an "upper" portion may actually be deeper underground than a different portion that is referred to as a "lower" portion.

The sub 1 comprises a generally tubular body 10 having a central bore 10b extending through the sub 1. Optionally, one or both of the ends may be provided with a fishing neck, or other formation to enable manipulation and/or retrieval of the sub 1 from a wellbore in the event of intervention operations being required. The upper end portion of the body 10 has, adjacent the box connection, a larger diameter than the lower end portion, and consequently the generally tubular components that are applied to the outer surface of the body 10 as the sub 1 is constructed each comprise a central bore which is offered to the body 10 as each component is passed over the relatively narrower lower end.

The sub 1 has a lower stabiliser assembly 20, a central cleaning device assembly 30, and an upper stabiliser assembly 40, which are all assembled around the outer surface of the body 10, typically with the upper stabiliser assembly and associated components being offered first to the lower end of the body, followed by

components of the cleaning device assembly 30, followed by components of the lower stabiliser assembly 20. Optionally more than two stabiliser assemblies can be provided. The stabilisers are typically axially spaced from one another along the sub 1. Typically all the components are incorporated on the same sub 1.

The central cleaning device assembly 30 typically comprises a number of cleaning devices in the form of cleaning pads 31 housed in recesses in the body 10 (best seen in the section view of fig 3 and fig 4). The recesses housing the pads 31 prevent lateral movement of the pads 31 in the recesses. The pads 31 are restrained against axial movement within the recesses by a central pad retaining ring 32, best seen in the section view of fig 6, which is welded or otherwise secured onto the outer surface of the body 10, and by outer pad retaining rings 33. The pad retaining rings 32, 33 define the axial boundaries of the recesses housing the pads 31, so that when the rings 32, 33 are in place, the pads are secured against axial and lateral movement within the recesses. The rings 32, 33 also typically have an internal undercut, best shown in the longitudinal section of fig 10, which extends over a portion of each pad 31, typically formed by upper lip on the axial ends of each pad 31. The interaction of the lips on the pads and the undercuts on the rings 32, 33 serves to restrain radial movement of the pads 31 within the recesses. Resilient devices such as springs are typically provided between the pads 31 and the body 10, and are typically held in compression, which serves to urge the pads radially outwards from the axis of the body 10, until the outer faces of the lips on each of the pads 31 engage the inner surfaces of the undercut formed on the rings 32, 33, which will limit the radial extension of their pads 31 out of the recesses. Accordingly, the pads 31 are restrained within the recesses on the body by the interaction of the recesses and the pad retaining rings 32, 33 so that the pads 31 are urged radially outward to the furthest extent under the force of the radially compressed springs, and limited inward radial movement of each pad 31 is permitted, when the force applied to the pad 31 exceeds the force of the springs. In that event, when the pad 31 is urged radially inward, for example if the tool is lying on the low side of a deviated well bore, and the full weight of the sub 1 is bearing down on one of the pads 31, then the springs supporting that particular pad 31 will tend to be compressed, allowing the pad 31 to move radially inwards, into the recess, but the boundaries of the recess, and the pad retaining rings 32, 33, will restrict lateral and axial movement of the pads 31.

The outer pad retaining rings 33 are typically provided with an internal screw thread on an area of the internal diameter that is spaced from the undercut, allowing the screw thread to cooperate with an external screw thread on the body 10. Accordingly, the pad retaining rings can be moved axially along the outer surface of the body 10 by means of the cooperating screw threads, to secure and release the lips on the pads 31. When the pads 31 are to be replaced, the pad retaining rings 33 can be backed off from the recess by means of the screw threads, to permit the pads 31 to be removed from the body 10.

Typically the central pad retaining ring 32 is formed as two half shells, as best shown in fig 6, which can typically be welded or bolted or otherwise attached to the central part of the recess in the body 10, typically after the upper stabiliser assembly 40 and the upper pad retaining ring 33 have been applied to the body and moved into their respective places.

Typically the pads 31 have arcuate outer cleaning surfaces that present cleaning formations such as brushes or scrapers covering circumferentially spaced apart areas on each pad 31, and the circumferential and axial offset allows overlap between the pads 31 to cover substantially the whole of the circumference of the body with cleaning surfaces, as can be seen in the section views of 2, 7 and 8. Typically the pads 31 are fixed to the body 10 of the sub 1 in recesses formed in the outer surface of the sub 1, and are therefore unable to rotate relative to the body.

Typically the body of the cleaning pads 31 on which the brushes or scrapers etc. are mounted has a smaller outer diameter than the outer diameter of the stabilisers (typically of the blades on the stabilisers) as best seen in fig 1, so that even when the pads 31 are urged outward to the maximum extent by the springs compressed between the pads 31 and the body 10, the body of the pads 31 does not engage the inner surface of the wellbore directly, but instead presses the cleaning formations such as the brushes and scrapers held on outer surface of the pads 31 against the inner surface of the wellbore tubular, so that the surface is cleaned by the pads 31, as seen in fig 1. This minimum standoff reduces wear on body of the pads 31.

The lower stabiliser assembly 20 comprises a tubular stabiliser body 21, typically having two axially spaced apart arrays of blades 22 projecting radially from the outer surface of the body 21. The blades 22 are arranged in circumferential rows, typically two rows, which are typically axially spaced apart from one another along the body 21, and in which, the respective blades 22 are typically circumferentially spaced apart from one another in each row. Typically each row of blades comprises more than two blades, for example 4, 5, 6 or more blades per row. Also, the blades 22 in the lower row are typically circumferentially staggered with respect to the blades 22 in the upper row. Typically the blades cover substantially 360 degrees of the circumference of the stabiliser assembly 20, in the same manner as the pads 31 on the cleaning device so that the combined outer surface of the blades on each stabiliser typically extends around substantially the whole circumference of the stabiliser. The blades 21 are typically aligned generally with the axis of the body 10. Between the blades 22 in each row, the stabiliser assembly 20 typically has a channel, allowing the flow of fluids in the annulus between the outer surface of the stabiliser body 21, and the inner surface of the wellbore tubular being cleaned. Each blade 22 is typically generally rectangular in shape, with ramp structures at each axial end, as best shown in fig 1, to permit the blades 22 to ride over obstructions on the inner surface of the wellbore tubular. Each blade, and the stabiliser assembly 20 general, is typically substantially radially incompressible, and so maintains a minimum stand-off (a minimum radial separation) between the outer surface of the stabiliser body 21, and the inner surface of the tubular being cleaned, which is typically dependent on the radial dimension of the blades 22. Accordingly, the height of the blades 22 typically defines the stand-off between the sub 1 and the inner surface of the tubular in which it is deployed. Typically the stabiliser body 21 is rotationally mounted on spaced apart races 23 of ball bearings 24. More than two bearing races could be used to support the body 21, and these are, spaced axially apart along the stabiliser body 21. The bearing races 23 each have an inner and an outer cup with a break line that intersects the bearings 24 (typically bisecting the bearings 24) thereby resisting axial thrust forces applied to the stabiliser body 21, and locking it in a secure axial position on the body 10 of the sub 1. Accordingly, the bearings 24 secure the stabiliser body 21 against axial movement along the body 10 of the sub 1, but of course facilitate free rotational movement. Typically the bearings 24 act alone to secure the stabiliser body 21 against axial movement along the sub 1, so that no other locking rings etc. are required. This reduces the rotational drag on the stabiliser body 21. The stabiliser body 21 can be spaced axially from other components, and can be maintained in that axially spaced relationship by means of the bearings 24. The bearings 24 are typically fed into the races 23 (when the stabiliser body 21 is positioned such that the inner and outer cups of the race 23 are axially aligned) through a radial port 25 set in the body of the stabiliser 21, typically extending through one of the blades 22. The port 25 is closed with a plug when the bearings have been inserted, which maintains the bearings in place in the race 23. The bearings 24 therefore cannot escape the race 23 once the port 25 is plugged, and hence they preserve the axial position of the stabiliser body 21 on the body 10 of the sub 1.

Optionally the bearings 24 are sealed by a pair of annular seals in the form of resilient 0 -rings 27 compressed between the stabiliser and the body in an axial position between the bearings and the end of the stabiliser. Two seals are provided to isolate the bearings 24 from the external environment and excluding the debris in the annulus from the space between the stabiliser 21 and the body 10. The stabiliser body 21 typically incorporates at least one (typically more than one) magnetic device in the form of a magnet 26 to attract and optionally retain ferrous metal particles onto the outer surface of the stabiliser assembly 20. In some examples, the magnets can be positioned on the outer surface of the stabiliser body 21. The magnets 26 are typically provided on portions of the outer surface of the stabiliser body 21 between the blades 22, for example in the channels, and between rows of blades 21. However, in the example shown here, the magnets 26 are typically positioned on the stabiliser assembly 20 below the stabiliser body.

Typically the nominal outer diameter of the body 21 is provided with a regular pattern of magnets, which are, optionally in the form of discs of high strength magnetic material that are received and retained within recesses that are spaced apart on the outer surface of the stabiliser assembly 20. Optionally, the magnets can comprise rare earth magnetic material, such as neodymium and/or samarium, and/or other high strength magnetic material. Typically the magnets 26 attract particulate metals that are suspended in the annulus between the tubular being cleaned and the body 10. This removes metallic particulates from the wellbore when the string is recovered.

Typically the outer surface of the blades 21 sweep circumferentially in arcuate curves around the axis of the body 10, as is best seen in the end section views of figs 2 and 8, but are typically flat in a plane parallel to the axis of the body 10, as is best seen in Fig 1 so that the outer arcuate surfaces of the blades 21 can optionally be matched to fit closely with the inner surface of the well bore tubular (e.g. casing C) to be cleaned, facilitating axial sliding and circumferential rotational movement of the blades 21 against the inner surface of the tubular to be cleaned.

The upper stabiliser assembly 40 has essentially the same structure as the lower stabiliser assembly 20, but differs in the provision of an integrated junk catcher 50. Similar parts between the upper and lower stabiliser assemblies are referenced with the same number, but increased by 20 in respect of the upper assembly 40, and the reader is referred to the earlier description for the lower stabiliser assembly for a description of the structure and function of such parts, which will not be repeated here in detail, for the sake of brevity. Accordingly, the upper stabiliser assembly 40 therefore comprises a stabiliser body 41, blades 42, bearing race 43, bearings 44, radial port 45, and magnets 46, all as previously described for the lower stabiliser body 21, blades 22, bearing race 23, bearings 24, radial port 25, and magnets 26.

At the upper end of the stabiliser body 41, the upper stabiliser assembly 40 typically incorporates an integral junk catcher 50, comprising a sleeve 51 that is typically concentric with the body 10, forming a blind ended annular catching chamber 53 concentric with the body 10, with an opening at its upper end, and radial drain holes 54 at least through the lower end of the sleeve 51, but typically extending substantially along the whole length of the sleeve 51. The chamber 53 is thus adapted to receive and typically to retain particulate matter suspended in fluid in the annulus between the body 10 and the well bore tubular being cleaned, during the cleaning operation. Typically the drain holes 54 permit fluids to drain from the chamber 53 and encourage particulate material to compact within the chamber, without passing through the drain holes 54. Typically the whole of the mouth at the upper end of the chamber 53 is open and points towards the upper end of the sub 1, parallel to the bore, allowing the chamber 53 to receive particulate materials that are sinking through the annulus. Typically the sleeve 51 is mounted below the larger diameter portion of the box connection at the upper end of the sub 1, and the sleeve 51 typically surrounds a reduced diameter section of the body 10 of the sub 1 which allows the capacity of the chamber 53 to increase while maintaining a consistent diameter between the body 41 of the stabiliser and the sleeve 51 of the junk catcher 50.

As the sleeve 51 is integral with (or could be a separate component but

subsequently connected to) the upper stabiliser assembly, it is rotationally locked to the stabiliser body 41, so the sleeve 51 can rotate relative to the body 10 in concert with the stabiliser 40.

Since the junk catcher sleeve is rotationally connected to the upper stabiliser body 41, and thus rotates relative to the 10 of the sub 1 with the stabiliser body 41, the inner wall of the chamber 53 formed by the body of the sub 1 rotates inside the outer wall of the chamber 53 formed by the body of the stabiliser 41, which leads to agitation of the junk within the chamber 53, which causes the junk within it to settle to the bottom of the chamber 53, thereby facilitating the accumulation of more junk in the chamber 53. This means that the same size of chamber 53 can have a higher capacity for junk, and that the junk contained within the chamber 53 can be more densely packed, which helps to resist migration of the junk out of the chamber 53.

The sleeve 51 has blades 52 that extend continuously from some of the blades 42 on the stabiliser, to support the standoff between the sleeve 51 and the casing C. The blades 52 are typically hollow creating internal channels extending longitudinally along the blades 52 parallel to the axis of the body, as best shown in the plan view of fig 5. This creates more space in the junk catcher chamber 53 to contain the particulate matter sampled during the trip, as well as maintaining the standoff along the length of the chamber 53. In addition, the channels on the inner surface of the blades 52 creates a discontinuous inwardly facing surface for the chamber 53, which assists in the compaction of the debris collected in the chamber 53.

The open upper end of the chamber 53 has a deflector in the form of a frusto-conical wiper 55 to deflect junk and particulate matter circulating in the annulus between the body of the sub 1 and the casing C into the chamber 53 for collection and return to surface for analysis. Typically the wiper 55 is connected to the outer surface of the sleeve 51 in a cantilever manner, with one narrow end secured to the outer surface of the sleeve 51, and a free outer end which extends radially and upwardly at an angle with respect to the axis of the sub 1, into the annulus. Typically the frusto-conical wiper 55 extending radially outward from the sleeve 51 has a cylindrical sleeve formed of the same material and secured to the outer surface of the sleeve 51 and connected to the frusto-conical section at the lower end. The outer free end of the wiper 55 diverges out and up above the narrow fixed end of the wiper at the lower end of the cylindrical sleeve, so that junk and particulates are channelled into the mouth of the chamber 53. The radially extending portion of the wiper 55 is typically movable between a radially extended position, shown in the drawings, and a radially collapsed position, folded substantially flat against the cylindrical portion on the outer surface of the sleeve 51, parallel to the axis of the sub 1. Typically the deflector is resilient and the outer free end of the deflector is resiliently energised radially outward to press against the casing C, so that when moving axially in the hole, the wiper 55 wipes the inner surface of the casing and channels the particulate matter in the annulus into the mouth of the chamber 53, for transport to the surface. Typically the wiper 55 is radially expanded by the action of pulling the body out of the bole, and is radially retracted by pushing into the hole, by virtue of the fluid pressure differentials generated in the annulus during axial movement of the body in the casing. In use, the sub 1 is connected into a tool string or work string which may typically incorporate other cleaning tools or tools that have other functions, and deployed in a wellbore lined with casing C to be cleaned. Typical well bores to be cleaned might include production tubing, casing, liner, or other kinds of well bore tubing. Typically the inner diameter of the wellbore tubing to be cleaned is known, and the outer diameter of the stabilisers and cleaning device assemblies can be adjusted to be a close fit with the same. The work string incorporating the apparatus is then run into the well, until the cleaning device assembly is in the location of the tubular to be cleaned, and the work string is then rotated to drive the cleaning device assembly in rotation relative to the tubular. The cleaning devices (pads etc.) rotate against the inner surface of the wellbore and clean debris. The pads can incorporate scrapers and/or brushes and/or other cleaning formations, suitable for the particular cleaning operation. The stabiliser bodies spaced on either side of the cleaning device assembly remain stationary with respect to the wellbore during the cleaning operation, and allow the body of the sub 1 to rotate within their bores. The stabiliser assemblies do not compress radially and so maintain a constant standoff between the cleaning pads and the inner surface of the wellbore, so that the brushes/scrapers etc. engage the inner surface but the solid pad bodies 31 retained in the recesses do not, thereby allowing and promoting continuous rotation with reduced risks of snagging the pad bodies 31 on the inner surface of the tubular being cleaned. Typically the work string can be axially reciprocated in the wellbore instead of or in addition to being rotated. The circumferential coverage of the pads 31 and of the blades maintains the standoff around the whole circumference reducing the risks of bottoming out of the string when a ledge or another incursion into the nominal inner diameter of the wellbore is encountered. The ramps on the axial ends of the blades help to maintain the standoff as the stabilisers ride axially over ridges and tool joints etc.

The cleaning pads 31 remove the particulate matter from the inner surface of the wellbore, and typically the cleaning operation is carried out with a circulation sub in the work string (typically below the sub 1) which promotes upward flow of the fluid that is pumped from surface down the central bore 10b of the string and out of the circulation sub, and is then diverted up the annulus between the work string and the tubular being cleaned. The particulates are therefore washed up the annulus to the surface, where they are typically recovered in mud processing apparatus. Any particulates dropping out of suspension while still in the annulus are typically trapped by the junk catcher 50, and are removed from the well with the string when the cleaning operation is finished. The junk catcher 50 packs the particulate matter more densely in the chamber 53 as a result of the relative movement of the inner and outer walls agitating the junk trapped therein. The discontinuities on the outer walls of the chamber 53 (formed by the channels on the inner surface of the blades 52) create additional agitation of junk in the chamber as the inner body 10 rotates relative to the stationary sleeve 51, which helps to settle the junk in the chamber, and ensure a more even distribution of the junk in the chamber. This reduces escape of the junk during tripping out of the hole, when typically the inner body 10 would not be rotating, and ensures that the junk trapped in the chamber 53 is more likely to be retained therein, and is more likely to be representative of the true conditions in the wellbore, particularly with respect to particulates. Also, the resilient wiper 55 typically folds flat when running the sub 1 into the hole, thereby reducing running in speeds and forces, and expands radially into the configuration shown in the drawings only when pulling out of the hole, so that the junk is channelled more effectively into the junk catcher for recovery to the surface, and is not pushed ahead of the sub 1.

Metallic particulates and larger metal pieces are attracted by the magnets 26, 46, and are thereby retained on the outer surface of the sub 1. These are also recovered from the well with the string after completion of the cleaning operation.

Referring now to figs 11-21, a second sub 101 is shown suitable for incorporation into a drill string for deployment in an oil or gas well, and has substantially the same features as the sub 1, which are referred to with the same reference number as used previously, but increased by 100. The reader is referred to the description of the earlier sub for additional description of the operation and structure of this sub 101.

The sub 101 comprises a generally tubular body 100, a lower stabiliser assembly 120 with blade 121, a central cleaning device assembly 130 with pads 131 that are similar to the pads 31, and an upper stabiliser assembly 140 having a stabiliser body 141 with blades 142 similar to those of the first sub 1. The components of the sub 101 are all assembled around the outer surface of the body 100 in the same manner as the sub 1. Magnets 126 similar to the magnets 26 are provided on the lower stab iliser b ody 121.

The upper stabiliser assembly 140 also has an integrated junk catcher 150. The reader is referred to the earlier description for the common parts between the two subs 1 and 101, which will not be repeated here in detail, for the sake of brevity. The upper stabiliser assembly 140 comprises a stabiliser body 141, blades 142, bearing race, bearings, radial port, and magnets 146, all as previously described. The differences between the sub 1 and the sub 101 reside in the junk catcher 150.

The junk catcher 150 comprises a sleeve 151 that is typically concentric with the body 100, forming a blind ended annular catching chamber 153 concentric with the body 100, with an opening at its upper end, and radial drain holes 154 as previously described, except that the drain holes are typically located in the lower part of the sleeve 151, although this can be varied in other aspects of the invention. The chamber 153 is adapted to receive and typically to retain particulate matter suspended in fluid in the annulus between the body 100 and the well bore tubular, typically during a work-over operation, such as wellbore cleaning. Typically the drain holes 154 permit fluids to drain from the chamber 153 and retain particulate material in a compact form within the chamber, without passing through the drain holes 154. Typically the whole of the mouth at the upper end of the chamber 153 is open and points towards the upper end of the sub 101, parallel to the bore, allowing the chamber 153 to receive particulate materials that are sinking through the annulus. Typically the sleeve 151 is mounted below the larger diameter portion of the box connection at the upper end of the sub 101, and the sleeve 151 typically surrounds a reduced diameter section of the body 100 of the sub 101 which allows the capacity of the chamber 153 to increase while maintaining a consistent diameter between the body 141 of the stabiliser and the sleeve 151 of the junk catcher 150.

The blades 152 on the outer surface of the junk catcher sleeve 151 can typically extend axially for the length of the chamber 153, and can typically be solid so the inner surface of the outer wall of the chamber that is formed by the sleeve is typically smooth and continuous in diameter, but optionally the sub 101 can have hollowed blades with a discontinuous inner surface similar to those described for the sub 1 if desired.

The junk catcher 150 has an impeller 156 mounted on the body 110 within the chamber 153, typically just below the opening of the mouth of the chamber 153. The impeller 156 is coupled to the body 110 and rotates with it. The impeller 156 has blades 157 that extend radially into the chamber, toward the inner surface of the sleeve 151. The faces of the blades 157 are typically provided with a hard facing or otherwise treated to increase hardness, for example, by being coated with tungsten carbide. Typically at least some of the surfaces of the blades can have different treatments. The upper and lower faces of the blades 157 are typically faced with a rough abrasive tungsten carbide coating, typically rough grade crushed tungsten carbide, such as "chunky bar", to assist in breaking up clumps of debris that are passing into the mouth of the chamber 153. The radially outermost faces of the blades 157 are typically faced with a less abrasive hard facing, to reduce the break-up of clumps of debris between the blades and the inner surface of the sleeve but still to increase the hardness of the outer surface of the blade 157.

The blades 157 are shaped as foils with a concave lower surface and a convex upper surface, and are typically arranged in the same orientation around the outer circumference of the body 110. Accordingly, as the body rotates in a clockwise direction as viewed from the top of the tool string, at an approximate speed of 100- 140 rpm, the blades 157 rotate with the body 110 with a leading edge higher than a trailing edge.

The rotation of the blades 157 generates downward thrust in the fluids in the chamber 153, drawing more particulate matter into the mouth of the chamber 153 and urging the particular matter suspended within the fluid in the chamber 153 towards the bottom of the chamber 153.

The abrasive hard facing on the upper, lower, and side surfaces of the blades 157 breaks up large clumps of debris in the region of the rotating impeller 156, entering the chamber, to enhance packing of the junk within the chamber 153, thereby increasing its capacity, and increasing the chances of retaining particulates representative of larger clumps, which may be too large to enter the chamber mouth without being broken up. The rotation of the impeller 156 with the body 110 maintains the downward thrust in the fluid within the chamber 153, which retains the junk already collected within the chamber 153.

According to a further aspect, the stabiliser and the junk catcher can optionally be formed integrally on a separate sub, typically without necessarily requiring the cleaning device, which can typically be omitted from examples according to this further aspect of the invention. Optionally, the separate sub incorporating the stabiliser in the junk catcher can be incorporated into different strings of tools, which optionally may include a cleaning device similar to the cleaning devices 30, 130. Optionally, additional stabilisers such as the lower stabiliser 20, 120 can typically be included on the same or a separate sub.

As the sleeve 151 is integral with (or could be a separate component but

subsequently connected to) the upper stabiliser assembly, it is rotationally locked to the stabiliser body 141, so the sleeve 151 can rotate relative to the body 100 in concert with the stabiliser 140.

Since the junk catcher sleeve is rotationally connected to the upper stabiliser body 141, and thus rotates relative to the body 110 of the sub 101 with the stabiliser body 141, the inner wall of the chamber 153 formed by the body 110 of the sub 101 rotates inside the outer wall of the chamber 153 formed by the body of the stabiliser 141, which leads to agitation of the junk within the chamber 153, and settling of the junk to the bottom of the chamber 153, thereby facilitating the accumulation of more junk in the chamber 153. This means that the same size of chamber 153 can have a higher capacity for junk, and that the junk contained within the chamber 153 can be more densely packed, which helps to resist migration of the junk out of the chamber 153. The sleeve 151 has blades 152 that extend continuously from some of the blades

142 on the stabiliser, to support the standoff between the sleeve 151 and the casing C. The blades 152 are typically solid as shown in the drawings (see particularly figure 15 but could also optionally be hollow as described for the first sub 1 and as shown in the plan view of fig 5, to create more space in the junk catcher chamber 153 to contain the particulate matter sampled during the trip, and providing a discontinuous inwardly facing surface for the chamber 153.

The open upper end of the chamber 153 has a deflector in the form of a frusto- conical wiper 155 to deflect junk and particulate matter circulating in the annulus between the body of the sub 101 and the casing C into the chamber 153 for collection and return to surface for analysis, essentially as previously described. As the deflector is mounted on the stabiliser, it does not rotate with the body 110, which reduces the wear on the deflector during rotation of the string from the surface.

In use, the sub 101 is connected into a tool string or work string and used as previously described for the sub 1. The impeller 156 enhances the junk collecting capacity of the sub 101.

Any particulates dropping out of suspension while still in the annulus are typically trapped by the junk catcher 150, and are removed from the well with the string when the cleaning operation is finished. The impeller 156 can optionally be rotated while pulling out of the hole to keep the junk in the chamber 153. The junk catcher 150 packs the particulate matter more densely in the chamber 153 as a result of the relative movement of the inner and outer walls agitating the junk trapped therein.

Claims

1. Apparatus for cleaning a well bore tubular, the apparatus comprising: a body having an axis and an axial bore through the body, suitable for connection into a tool string for use in a well bore tubular; a cleaning device mounted on the outer surface of the body for engaging an inner surface of the well bore tubular; a stabiliser arranged on the outer surface of the body and protruding radially outwards from the body towards the inner surface of the well bore tubular, wherein the stabiliser is adapted to resist radial compression and thereby maintain a constant radial separation between the body and a radially outer surface of the stabiliser, wherein the stabiliser is rotatably mounted on the body; and incorporating a junk catcher, comprising a junk-receiving chamber with an opening at one end of the chamber, adapted to receive particulate matter suspended in fluid in the annulus between the body and the well bore tubular, wherein the junk catcher is arranged to agitate the contents of the chamber by the relative rotation of portions of the chamber.

2. Apparatus as claimed in claim 1 wherein the junk catcher has an impeller device arranged to generate thrust in the chamber.

3. Apparatus as claimed in any one of claims 1-2, wherein the impeller device is non-rotatably connected with the body, so that rotation of the body rotates the impeller device.

4. Apparatus as claimed in any one of claims 1-3, wherein the impeller device is disposed within the chamber, and is secured on the inner wall of the chamber.

5. Apparatus as claimed in any one of claims 1-4, wherein the impeller device has at least one blade in the form of a foil.

6. Apparatus as claimed in claim 5, wherein the or each blade has a concave lower face and a convex upper face, and a leading edge (in the direction of rotation of the impeller device) that is disposed above a trailing edge of the blade.

7. Apparatus as claimed in any one of claims 5-6, wherein at least one blade has at least one hardened face coated with a hardened material.

8. Apparatus as claimed in claim 7, wherein first and second faces of the coated blade have respectively different hardness.

9. Apparatus as claimed in claim 7 or claim 8, wherein each blade has a radially outermost face and upper, lower and front and rear faces, and wherein the radially outermost face of each blade typically has a smoother surface than the upper, lower and front and rear faces of the blade.

10. Apparatus as claimed in any one of claims 7-9 wherein the upper, lower, front and rear faces of each blade have abrasive coating of a hardened material, to break up clumps of particulate material suspended within the fluid, and to reduce the particle size of the material collected in the chamber.

11. Apparatus as claimed in any one of claims 1-10, wherein at least two stabilisers are provided, and are axially spaced from one another along the body.

12. Apparatus as claimed in any of claims 1-11, wherein the or each stabiliser is rotationally mounted on bearings on the body, wherein the bearings are housed in at least two bearing races, spaced axially apart along the or each stabiliser.

13. Apparatus as claimed in any of claims 1-12, wherein the or each stabiliser is rotationally secured against axial movement on the body solely by the bearing races and bearings.

14. Apparatus as claimed in any of claims 1-13, wherein, the apparatus comprises at least one two radially projecting blades, which extend outwardly from the outer surface of the body of a stabiliser in a radial direction.

15. Apparatus as claimed in claim 14, wherein at least two blades are provided on each stabiliser, and wherein the blades are spaced circumferentially around the stabiliser with respect to one another.

16. Apparatus as claimed in claim 15 wherein the blades are arranged at the same axial location on the stabiliser to form a row.

17. Apparatus as claimed in claim 16, wherein: each row of blades comprises more than two blades, each stabiliser has more than one row of blades, the rows of blades on each stabiliser are axially spaced from one another along the stabiliser, and the blades in each row are circumferentially staggered with respect to the blades in another row, whereby the blades in one row are aligned with the channels in an adjacent row.

18. Apparatus as claimed in claim 17 wherein the combined radially outermost surface of the blades on each stabiliser extends around substantially the whole circumference of the stabiliser.

19. Apparatus as claimed in any one of claims 1-18, wherein the apparatus incorporates at least one magnetic device to attract and retain ferrous metal particles.

20. Apparatus as claimed in claim 19, having a plurality of magnetic devices arranged on the outer surface of the stabiliser.

21. Apparatus as claimed in any one of claims 19-20, wherein the magnetic devices are arranged in a pattern wherein each magnetic device is spaced from other magnetic devices.

22. Apparatus as claimed in claim 21, wherein the cleaning device incorporates at least one cleaning pad each having a body and cleaning formations extending radially from the body and supported by the body, and wherein the radially outermost diameter of the outer surface of the blades on each stabiliser is less than the maximum outer diameter of cleaning formations which extend radially outward from the cleaning pads, but greater than the body of the cleaning pads supporting the cleaning formations.

23. Apparatus as claimed in any one of claims 1-22, wherein the cleaning device has cleaning surfaces that present cleaning formations in the form of brushes and/or pads, and wherein the cleaning surfaces cover circumferentially spaced apart areas on each cleaning device and wherein the spaced apart areas of cleaning surfaces extend around substantially the whole of the circumference of the body.

24. Apparatus as claimed in any one of claims 1-23, wherein the cleaning device incorporates at least one cleaning pad each having a body and cleaning formations extending radially from the body and supported by the body, and wherein the cleaning pad is mounted on a resilient device held in compression against the body of the apparatus, so as to urge the cleaning pad radially outward against the inner surface of the well bore tubular being cleaned.

25. Apparatus as claimed in any one of claims 1-24, wherein the cleaning device incorporates at least one cleaning pad each having a body and cleaning formations extending radially from the body and supported by the body, and wherein the cleaning pad is fixed to the body of the apparatus in a recess formed in the outer surface of the body, and is unable to rotate relative to the body whereby torque and axial thrust applied to the body is transmitted to the cleaning pad.

26. Apparatus as claimed in any one of claims 1-25, wherein the cleaning device incorporates at least one cleaning pad each having a body and cleaning formations extending radially from the body and supported by the body, and wherein the cleaning pad is removably connected to the body of the apparatus.

27. Apparatus as claimed in any preceding claim, wherein the junk catcher has drain holes configured to retain junk within the chamber but to allow draining of fluids from the chamber.

28. Apparatus as claimed in claim 22, wherein the junk-receiving chamber has an outer wall and an inner wall, and wherein the inner and outer wall of the chamber are arranged to rotate relative to one another, and thereby agitate the contents of the chamber.

29. Apparatus as claimed in any preceding claim wherein the junk-receiving chamber has an outer wall and an inner wall, and wherein one of the inner and outer walls of the chamber is non-rotatably connected with the stabiliser and the other of the inner and outer walls of the chamber is non-rotatably connected with the body, wherein rotation of the body relative to the stabiliser rotates one of the inner and outer walls of the chamber relative to the other.

30. Apparatus as claimed in any one of claims 1-29, wherein the chamber has a deflector to deflect junk and particulate matter circulating in the annulus between the body and the casing into the chamber, wherein the deflector is has a first fixed end connected to the outer surface of the junk chamber by a cantilever joint, and a second free end of the deflector which extends radially outward from the junk catcher at an angle with respect to the axis of the body, wherein the outer free end of the deflector is above the cantilever joint, whereby the deflector channels junk and particulates above the deflector into the mouth of the chamber.

31. Apparatus as claimed in claim 30, wherein the deflector is movable between a radially extended position and a radially retracted position, in which the free end of the deflector is closer to the body than in the radially collapsed position than in the radially extended position.

32. Apparatus as claimed in claim 30 or 31, wherein the deflector is resilient, and wherein the outer free end of the deflector is resiliently energised radially outward.

33. Apparatus as claimed in any one of claims 1-32, wherein the body, cleaning device and stabiliser are incorporated on the same sub.

34. A method of cleaning a well bore tubular, the method comprising: providing a cleaning apparatus comprising a body having an axis and an axial bore through the body; mounting a cleaning device on the outer surface of the body; rotatably mounting a stabiliser arranged on the outer surface of the body and protruding radially outwards from the body, wherein the stabiliser is adapted to resist radial compression; providing a junk catcher on the body comprising a chamber to receive particulate matter suspended in fluid in the annulus between the body and the well bore tubular; wherein at least a part of the junk catcher is rotationally connected with at least one stabiliser and rotates relative to the body with the stabiliser;

connecting the apparatus into a tool string and running the tool string into the well bore tubular; engaging the outer surface of the stabiliser against the inner surface of the wellbore tubular, maintaining a constant radial separation between the outer surface of the body and the outer diameter of the non-radially compressible stabiliser; and rotating the body with respect to the stabiliser as the stabiliser remains stationary relative to the wellbore tubular to rotate the cleaning devices against the inner surface of the wellbore tubular, and rotating a first portion of the junk catcher relative to a second portion of the junk catcher.

35. A method as claimed in claim 34, wherein the chamber has a deflector to deflect junk and particulate matter circulating in the annulus between the body and the casing into the chamber, and wherein the method includes deflecting junk and particulates above the deflector into the mouth of the chamber.

36. A method as claimed in claim 35, wherein the deflector is movable between a radially extended position and a radially retracted position, in which the free end of the deflector is closer to the body than in the radially collapsed position than in the radially extended position, and wherein the method includes expanding the deflector against the inner surface of the casing when pulling the cleaning apparatus out of the well.

37. A junk basket assembly for incorporating in a work string for removing particulate materials from a well bore tubular, the assembly comprising: a body having an axis and an axial bore through the body, suitable for connection into a tool string for use in a well bore tubular; a chamber for receiving particulate matter suspended in fluid in the wellbore, the chamber comprising an outer wall and an inner wall radially inside the outer wall; a stabiliser protruding radially outwards from the outer surface of the body towards the inner surface of the well bore tubular, the stabiliser being resistant to radial compression to maintain a constant radial separation between the body and a radially outer surface of the stabiliser; wherein the stabiliser is rotatably mounted on the body; wherein the outer wall of the chamber is non-rotatably connected with the stabiliser and the inner wall of the chamber is non-rotatably connected with the body; wherein rotation of the body relative to the stabiliser rotates one of the inner and outer walls of the chamber relative to the other.

38. A junk basket assembly as claimed in claim 37, incorporating an impeller device arranged to generate thrust in the chamber.

39. A junk basket assembly as claimed in claim 38 wherein the impeller device is non-rotatably connected with the body, so that rotation of the body rotates the impeller device relative to the stabiliser.

40. A junk basket assembly as claimed in any one of claims 38-39, wherein the impeller device is disposed within the chamber, and is secured on the inner wall of the chamber.

41. A junk basket assembly as claimed in any one of claims 38-40, wherein the impeller device has at least one blade in the form of a foil.

42. A junk basket assembly as claimed in claim 41, wherein the or each blade has a concave lower face and a convex upper face, and a leading edge (in the direction of rotation of the impeller device) that is disposed above a trailing edge of the blade.

43. A junk basket assembly as claimed in any one of claims 41-42, wherein at least one blade has at least one hardened face coated with a hardened material.

44. A junk basket assembly as claimed in claim 43, wherein first and second faces of the coated blade have respectively different hardness.

45. A junk basket assembly as claimed in claim 43 or claim 44, wherein each blade has at least one face selected from the group comprising a radially outermost face and upper, lower and front and rear faces, and wherein the radially outermost face of each blade typically has a smoother surface than at least one of the upper, lower and front and rear faces of the blade.

46. A junk basket assembly as claimed in any one of claims 43-45 wherein at least one of the upper, lower, front and rear faces of each blade have an abrasive coating of a hardened material, to break up clumps of particulate material suspended within the fluid, and to reduce the particle size of the material collected in the chamber.

47. A junk basket assembly as claimed in any one of claims 37-46 wherein at least a portion of the inner walls of the basket is faced with a hardened material.