Patent Description:
Many operations in an oil or gas well often produce a variety of debris in the wellbore. For example, milling operations may produce metallic mill cuttings, which may not be completely removed by simple circulation of fluid in the wellbore. Retrieval tools containing magnets have been used to collect the debris in wellbores. Magnetic retrieval tools typically have magnets disposed on the exterior of the tool. Having the magnets continuously attracting metallic objects is problematic as there are times when the tool needs to be non-attractive to debris, like during run-in. Some tools have electro magnets that can be turned on and off remotely from the surface. These are unreliable and often require a source of power downhole. In any case, having magnets exposed even when not in use increases the chance of damage and malfunction. Documents <CIT> and <CIT> disclose different magnetic tools for use in wellbores.

There is a need, therefore, for an improved magnetic retrieval tool for retrieving debris from the wellbore.

Aspects and embodiments of the present disclosure are defined herein in accordance with the appended claims.

According to the present invention a magnetic debris collection tool for use in a subterranean wellbore comprises:.

The present disclosure relates to a debris collection tool for retrieving metallic debris from a wellbore. The debris collection tool has magnets, and may use magnetic fields to attract metallic debris. The debris collection tool may be switched between an inactive configuration, in which the magnetic fields emanating from the debris collection tool are relatively weak, and an activated configuration, in which the magnetic fields emanating from the debris collection tool are relatively strong.

The debris collection tool may include components or materials that are deemed to be "magnetic" or "non-magnetic. " A material that is termed "non-magnetic" has a low relative magnetic permeability, whereas a material that is termed "magnetic" has a high relative magnetic permeability. Magnetic permeability is a measure of the ability of a material to support the formation of magnetic fields. Relative magnetic permeability is the ratio of the magnetic permeability of the particular material to the magnetic permeability of free space (i.e. a vacuum), and is denoted by the equation: <MAT> where µr is the relative magnetic permeability of the material, µ is the actual magnetic permeability of the material, and µ<NUM> is the actual magnetic permeability of free space.

Table <NUM> provides some example values of relative magnetic permeability for selected materials.

Table <NUM> shows that <NUM>% pure iron annealed in hydrogen has a higher relative magnetic permeability than <NUM>% pure iron, which has a higher relative magnetic permeability than nickel, which has a higher relative magnetic permeability than aluminum and wood. Thus, as used herein, the terms "magnetic" and "non-magnetic" may be considered as relative terms.

The debris collection tool <NUM> of the present disclosure is primarily made up of two assemblies: a cover assembly and a magnet assembly. <FIG> is a perspective view of the cover assembly <NUM>. The assembly is constructed and arranged to cover a magnet assembly <NUM> (<FIG>, <FIG>) that moves axially within the cover assembly to expose or cover a plurality of magnet groups <NUM>. The cover assembly <NUM> includes an upper and lower end caps <NUM> and includes a bore <NUM> extending the length of the assembly. The assembly also includes a plurality of spaced covers <NUM> each of which is separated from an adjacent cover by spacer pins <NUM>. Upper and lower end covers <NUM> are wider than the other covers.

<FIG> is an exploded view of the cover assembly <NUM> of <FIG>. Visible in the exploded view are the end caps <NUM>, covers <NUM>, and spacer pins <NUM> introduced in <FIG>. Additionally visible are an inner tube <NUM>, a particle shield <NUM>, and a ring assembly <NUM>.

<FIG> and <FIG> are perspective views of the magnet assembly <NUM>. The magnet assembly, in the embodiment shown is installed inside and axially movable within the cover assembly <NUM> in a manner whereby magnet groups <NUM> are covered when the tool <NUM> is in a deactivated position but exposed in an activated position. The assembly <NUM> includes a carrier <NUM> having a bore therethrough. Each magnet group consists of magnets disposed radially around the body of the carrier. Each individual magnet <NUM> is attached to the carrier by a fastener <NUM>. In addition to housing the magnets, the carrier has a piston surface <NUM> at an upper end and acts as an annular piston to shift the magnet assembly <NUM> between the two positions of the tool <NUM>. <FIG> is an enlarged view of a lower end of the carrier <NUM>. As shown, the carrier has a reduced diameter portion <NUM> at a lower end with a shoulder <NUM> formed at a transition point between the two outer diameters. The reduced diameter portion and shoulder are integral to shifting the tool <NUM> as will be explained herein.

<FIG> is a front view of the assembled tool <NUM> showing the covers <NUM>, <NUM> as well as the spacer pins <NUM> separating the covers. <FIG> and <FIG> are section views of the deactivated tool <NUM> taken along lines <NUM>-<NUM> and <NUM>-<NUM> of <FIG>. At the center of <FIG> is bore <NUM> formed in the inner tube <NUM> of the cover assembly <NUM>. Surrounding the inner tube and axially movable relative to the inner tube is the carrier <NUM> and mounted on its outer surface are the magnets <NUM> attached to the carrier in radial groups <NUM> with the fasteners <NUM> also visible in the Figure. Surrounding the carrier <NUM> and magnet groups <NUM> is the particle shield <NUM> with a space provided between the two parts. As will be shown and explained herein, the particle shield <NUM> is a thin member that functions to prevent magnetically attracted debris from actually coming into contact with the magnets <NUM>. Covering the particle shield is one of the covers <NUM> with a space between the two parts. <FIG> is a section view taken through another portion of the deactivated tool <NUM>. The inner tube <NUM>, carrier <NUM>, and particle shield <NUM> are visible as well as two of the spacer pins <NUM>. The magnets <NUM> and cover <NUM> are labeled but not directly visible in the section view of <FIG>.

<FIG> is a section view showing the relationship between the covers <NUM> and magnets <NUM> of the tool <NUM> in its deactivated position. Visible is the inner tube <NUM>, carrier <NUM>, magnets <NUM>, fasteners <NUM>, covers <NUM> and particle shield <NUM>. In the deactivated position, each magnet is underneath a cover preventing its magnetic properties from escaping to the wellbore (not shown) surrounding the tool <NUM>. As will be illustrated and described herein, shifting the tool <NUM> to the activated position includes moving the carrier with the attached magnets downwards in relation to the covers <NUM> in order to expose them to debris in the wellbore.

<FIG> is an enlarged section view showing an upper actuation portion of the tool <NUM>. As explained, an upper surface <NUM> of the carrier <NUM> operates as a piston surface causing the carrier to operate as an annular piston when a predetermined fluid pressure is placed on surface <NUM>. Shown in the Figure is a port <NUM> creating a fluid path between the bore of the tool <NUM> and surface <NUM>. As the tool <NUM> moves to the activated position, the carrier and magnets will move down to a location wherein the magnets are no longer blocked by the covers130, <NUM>.

<FIG> is an enlarged section view showing a lower actuation portion of the tool <NUM>. Visible is a lower, reduced diameter portion <NUM> of carrier <NUM> having a lower face <NUM> constructed and arranged to act on a ring assembly <NUM> in order to initiate the transition of the tool <NUM> to the activated position. The ring assembly includes a first ring <NUM> having an inwardly extending shearable arm <NUM> that is acted upon by lower face <NUM> and a wavy ring <NUM> constructed and arranged to flatten and reform in order to compensate and absorb shock from unrelated pressure events in the wellbore that might otherwise actuate the tool <NUM> at an unwanted time. <FIG> is a front view of the wavy ring <NUM> in its natural, wavy state.

In the deactivated position shown in <FIG>, face <NUM> is resting on shearable arm <NUM> and ring <NUM> retains its natural, wavy shape. <FIG> is an enlarged section view showing the same parts of the tool <NUM> as <FIG>. In this view, the carrier <NUM> acting as an annular piston, has been acted upon at an upper end (not shown) by pressurized fluid and lower face <NUM> has applied enough pressure on the shearable arm <NUM> to cause it to flatten the wavy ring <NUM>. In <FIG>, an enlarged view of the same portions of the tool <NUM>, fluid pressure applied to the carrier <NUM> has increased to the point where the shearable arm <NUM> of ring <NUM> has failed and the carrier <NUM> with its magnet groups <NUM> is moving downwards to its final, activated position. The downward movement is shown by arrow <NUM>.

<FIG> is an enlarged section view showing the same portions of the tool <NUM> as the previous views, but showing the tool <NUM> in its final activated position. In this position, the carrier has moved downwards relative to the other portions of the tool <NUM> until shoulder <NUM> formed between the different diameters of the carrier has contacted an upper face of first ring <NUM> preventing additional downward movement.

<FIG> is a section view showing an upper portion of the unactuated tool <NUM> in a wellbore <NUM> with debris <NUM> visible in an annular area <NUM> between the tool <NUM> and the wellbore walls. As shown, each magnet <NUM> of each magnet group <NUM> is blocked by a cover <NUM>, <NUM>. The unactuated position of the tool <NUM> would be typical during run-in or in the case of multiple operations in the wellbore, at some point prior to a time when collection of debris is needed. For example, in a drilling operation, the tool <NUM> might remain in its unactuated position until drilling has taken place. In other instances, the tool <NUM> will be run-in but only actuated after fluid has been circulated in the annulus <NUM> to stir up debris <NUM> and make it easier to attract magnetically. <FIG> is a section view of the same upper portion of the tool <NUM> shown in <FIG>. However, in <FIG> the tool <NUM> is fully actuated and the magnets <NUM> are "uncovered" with only the particle shield <NUM> between the magnets and the debris <NUM> that is being collected.

In one embodiment, the tool <NUM> includes a reset assembly <NUM> permitting the tool <NUM> to be easily moved to the unactuated state once it has been recovered at the surface of a well. Shifting the tool <NUM> back to its original position is useful for cleaning the various parts of the tool <NUM> before it is returned to a facility to be readied for another use.

<FIG> is a section view of a reset assembly shown with the tool <NUM> in the unactuated position. The reset assembly <NUM> is constructed and arranged to apply pressure to the carrier <NUM> in order to return it to its original position relative to the cover assembly <NUM>. The assembly <NUM> includes a spring-loaded reset piston <NUM> with a spring <NUM> initially held in a compressed position be two retainers <NUM>. In the embodiment shown, the spring remains compressed throughout the downhole operation of the tool <NUM>.

<FIG> is a section view of the reset assembly <NUM> shown with the tool <NUM> in the actuated position. As shown, in the actuated position, the carrier <NUM> has moved downwards relative to the cover assembly <NUM> and the magnets <NUM> are exposed to the wellbore where they may attract debris (see <FIG>). In this position the lower surface <NUM> of the reduced diameter portion <NUM> of the carrier <NUM> abuts an upper end <NUM> of the spring-loaded reset piston <NUM> which remains anchored in the charged/compressed position by the retainers <NUM>.

<FIG> is a section view of the reset assembly <NUM> shown after the tool <NUM> has been reset at the surface of the well. More specifically, retainers <NUM> have been loosened until they no longer interfere with the movement of the spring loaded reset piston <NUM> and the piston has moved upwards taking the magnet carrier <NUM> with it until the carrier is in the original, unactuated position with each magnet <NUM> blocked by a cover <NUM>. In the position any collected debris can be removed prior to transporting the tool <NUM>.

In operation, the tool <NUM> is run into a wellbore on a string of tubulars at such time as there is a need to collect iron-containing-type debris. The tool <NUM> may be run-in alone or in combination with other tools like a drill bit. A drilling operation may be conducted while the tool <NUM> is in the wellbore prior to actuating the tool <NUM>. At any time there is a need for collection of debris, the tool <NUM> can be actuated by providing a predetermined amount of fluid pressure, typically from the surface via port <NUM> to the upper surface <NUM> of the carrier <NUM>. Typically, fluid is circulated in the annulus of the wellbore before or at the time the tool <NUM> is shifted to its actuated position. Once a desired amount of debris is collected, usually determined by circulating over a set period of time, the tool <NUM> can be removed from the wellbore, the debris discarded, and the tool <NUM> re-set at the surface for another use.

<FIG> is a perspective view of a debris collection tool <NUM>. The debris collection tool <NUM> may include an upper housing <NUM>. The upper housing <NUM> may have an upper centralizer <NUM>. In some embodiments, the upper centralizer <NUM> may move axially and/or rotationally relative to the upper housing <NUM>. In some embodiments, the upper centralizer <NUM> may not move axially or rotationally relative to the upper housing <NUM>. In some embodiments, the upper centralizer <NUM> and the upper housing <NUM> have a unitary construction. The upper housing <NUM> may be coupled to a bulkhead <NUM> of a mandrel <NUM> (see <FIG>). The bulkhead <NUM> may be coupled to an upper bonnet <NUM>, which may be coupled to a cover <NUM>. The cover <NUM> may be coupled to a lower bonnet <NUM>, which may be coupled to a lower housing <NUM>. The lower housing <NUM> may have a lower centralizer <NUM>. In some embodiments, the lower centralizer <NUM> may move axially and/or rotationally relative to the lower housing <NUM>. In some embodiments, the lower centralizer <NUM> may not move axially nor rotationally relative to the lower housing <NUM>. In some embodiments, the lower centralizer <NUM> and the lower housing <NUM> have a unitary construction.

In some embodiments the upper housing <NUM> may be omitted. In some embodiments the upper centralizer <NUM> may be omitted. In some embodiments the lower housing <NUM> may be omitted. In some embodiments, the lower centralizer <NUM> may be omitted. The debris collection tool <NUM> may be configured to be connected to other tools and/or a workstring at the bulkhead <NUM> or, if present, the upper housing <NUM>. The debris collection tool <NUM> may have a central longitudinal flowbore <NUM> that continues from an upper end of the upper housing <NUM>, through the mandrel <NUM>, and down to a lower end of the lower housing <NUM>. The debris collection tool <NUM> may be configured to be connected to other tools and/or a workstring at the lower bonnet <NUM> or, if present, the lower housing <NUM>.

<FIG> is an exploded view of some components of the debris collection tool <NUM>. <FIG> is an exploded view of some additional components of the debris collection tool <NUM>. As shown in <FIG>, a mandrel <NUM> may include the bulkhead <NUM>. In some embodiments, the bulkhead <NUM> and the mandrel <NUM> may be formed as a unitary component. In some embodiments, the bulkhead <NUM> and the mandrel <NUM> may include multiple parts that are coupled together. The upper bonnet <NUM> may encircle the mandrel <NUM> in order to be coupled to the bulkhead <NUM>. An upper shield <NUM> may encircle the mandrel <NUM> and be coupled to an interior portion of the upper bonnet <NUM>. A cover <NUM> may encircle the mandrel <NUM> and be coupled to an interior portion of the upper bonnet <NUM>. An outer magnet array <NUM> may encircle the mandrel <NUM> and inside the cover <NUM>. The lower bonnet <NUM> may encircle the mandrel <NUM> and be coupled to a lower end of the cover <NUM>. A lower shield <NUM> may encircle the mandrel <NUM> and be coupled to an interior portion of the lower bonnet <NUM>. A floating piston <NUM> may encircle the mandrel <NUM> and be coupled to an interior portion of the lower bonnet <NUM>.

<FIG> provides a perspective view of an outer magnet assembly <NUM> that forms part of the outer magnet array <NUM>. The outer magnet array <NUM> may include one or more outer magnet assembly <NUM>. The outer magnet assembly <NUM> may include an upper end band1032 and a lower end band <NUM>. The upper end band <NUM> and the lower end band <NUM> may be annular in shape. In some embodiments, the upper end band <NUM> and the lower end band <NUM> may be made out of a substantially non-magnetic material. A ring <NUM> of outer magnets <NUM> may be disposed between the upper end band <NUM> and the lower end band <NUM> such that each outer magnet <NUM> is coupled to the upper end band <NUM> and the lower end band <NUM>. The outer magnets <NUM> may be arranged in the ring <NUM> such that the poles of each outer magnet <NUM> are circumferentially aligned. The outer magnets <NUM> may be arranged to form the ring <NUM> such that the North pole of one outer magnet <NUM> is facing the North pole of a neighboring outer magnet <NUM>. Similarly, the South pole of one outer magnet <NUM> may be facing the South pole of another neighboring outer magnet <NUM>.

Each pair of circumferentially adjacent outer magnets <NUM> of a ring <NUM> of outer magnets <NUM> may be separated by a bridge <NUM>. Each outer magnet <NUM> may be circumferentially adjacent to a bridge <NUM> at the outer magnet's <NUM> North pole and another bridge <NUM> at the outer magnet's <NUM> South pole. Hence the ring <NUM> of outer magnets <NUM> may include a circumferentially aligned sequence of components in which the components form an alternating sequence of outer magnet <NUM>, bridge <NUM>, outer magnet <NUM>, bridge <NUM>, and so on. Each bridge <NUM> may be formed from a magnetic material, such as a grade of steel that has a relatively high relative magnetic permeability. In some embodiments, one or more bridge <NUM> may be sized to extend radially inwardly of the ring <NUM> of outer magnets <NUM>.

Successive rings <NUM> of outer magnets <NUM> may be axially aligned to form the outer magnet array <NUM>. Each outer magnet <NUM> within a ring <NUM> of outer magnets <NUM> may be axially aligned with a corresponding outer magnet <NUM> of an adjacent ring <NUM> of outer magnets <NUM>. Hence, the outer magnets <NUM> may be aligned in rows in addition to being aligned circumferentially. Additionally, each bridge <NUM> within a ring <NUM> of outer magnets <NUM> may be axially aligned with a corresponding bridge <NUM> of an adjacent ring <NUM> of outer magnets <NUM>. Hence, the bridges <NUM> may be aligned in rows in addition to being aligned circumferentially.

Each outer magnet <NUM> may include a magnetic material. Some example magnetic materials may include, without limitation, ceramic ferrite, neodymium iron boron, samarium cobalt, and aluminum nickel cobalt. The magnetic material may be encased in a non-magnetic material, such as stainless steel, for the physical and chemical protection of the magnetic material.

<FIG> is an exploded view of some components of the debris collection tool <NUM> that are additional to the components shown in <FIG>. <FIG> is a perspective view of the components of <FIG> as assembled according to one embodiment. The debris collection tool <NUM> may have an inner sleeve <NUM> coupled to an adaptor sleeve <NUM> by a linkage <NUM>. The inner sleeve <NUM> may encircle the mandrel <NUM>, and may have an inner magnet array <NUM>. The inner magnet array <NUM> may be mounted on an outer surface of the inner sleeve <NUM>. The inner sleeve <NUM> may have one or more aperture <NUM> that is sized to accept a key <NUM> of the linkage <NUM>. The linkage <NUM> may include one or more key <NUM>, and each key <NUM> may be coupled to an elongate member <NUM>, such as a rod, a strip, a wire, or a tube. The elongate member <NUM> may be coupled to a yoke <NUM>. In some embodiments, one end of the elongate member <NUM> may be coupled to a key <NUM> and the other end of the elongate member <NUM> may be coupled to the yoke <NUM>. In some embodiments that include multiple elongate members <NUM>, the multiple elongate members <NUM> may be coupled to a single yoke <NUM>. In some embodiments, the yoke <NUM> may be a unitary member. In some embodiments, the yoke <NUM> may include multiple parts coupled together. The yoke <NUM> may be coupled to an outer surface of the adaptor sleeve <NUM>. In some embodiments, the coupling between the yoke <NUM> and the adaptor sleeve <NUM> may include one or more fastener <NUM>, such as a set screw, a snap ring, a latch, a locking dog, etc. Because of the one or more fastener <NUM>, the yoke <NUM> may have limited scope for axial movement relative to the adaptor sleeve <NUM>. In some embodiments, the yoke <NUM> may be coupled to the adaptor sleeve <NUM> such that the yoke <NUM> and the adaptor sleeve <NUM> may rotate independently of, and relative to, one another.

In some embodiments, the adaptor sleeve <NUM> may be coupled to an adaptor assembly <NUM>. In some embodiments, the adaptor assembly <NUM> may be omitted. In some embodiments, the adaptor assembly <NUM> may be configured to couple the adaptor sleeve <NUM> to a tool positioned close to the debris collection tool <NUM>. The tool positioned close to the debris collection tool <NUM> may be a controller, such as any of the controllers <NUM> depicted in <FIG> and <FIG>. In some embodiments, a tool, such as a controller, may be positioned close to the debris collection tool <NUM>, and may be coupled to the adaptor sleeve <NUM> without an intermediate adaptor assembly <NUM>. In some embodiments, the adaptor assembly <NUM> may include a single component. In some embodiments, the adaptor assembly <NUM> may include multiple components.

As illustrated in <FIG>, the adaptor assembly <NUM> may include an adaptor piston <NUM> having an adaptor skirt <NUM>. The adaptor skirt <NUM> may be generally cylindrical, and may be sized to fit inside the adaptor sleeve <NUM>. The adaptor sleeve <NUM> may be coupled to the adaptor skirt <NUM>, and retained in position using a fastener <NUM>, such as a set screw, a snap ring, a latch, a locking dog, etc. In some embodiments, a longitudinal position of the adaptor sleeve <NUM> on the adaptor skirt <NUM> may be adjusted. In some embodiments, the longitudinal position of the adaptor sleeve <NUM> on the adaptor skirt <NUM> may be adjusted by merely sliding the adaptor sleeve <NUM> to a desired position. In some embodiments, the longitudinal position of the adaptor sleeve <NUM> on the adaptor skirt <NUM> may be adjusted by altering a threaded engagement between the adaptor sleeve <NUM> and the adaptor skirt <NUM>. In some embodiments, the adaptor assembly <NUM> may include an adaptor extension <NUM> coupled to the adaptor piston <NUM>. The adaptor extension <NUM> may include one or more port <NUM>. The adaptor extension <NUM> may include a debris filter <NUM> associated with the one or more port <NUM>.

<FIG> is a perspective view of a portion of the inner magnet array <NUM> mounted on an outer surface of the inner sleeve <NUM>. The inner sleeve <NUM> may be generally cylindrical and having inner and outer surfaces. The outer surface may have one or more longitudinal groove <NUM>. An array <NUM> of inner magnets <NUM> may be disposed on the outer surface of the inner sleeve <NUM>. The inner magnets <NUM> may be arranged such that the inner magnets <NUM> may be axially aligned in rows. The inner magnets <NUM> may be arranged such that the inner magnets <NUM> may be circumferentially aligned. Thus, each group of circumferentially aligned inner magnets <NUM> forms a ring <NUM> of inner magnets <NUM>. The inner magnets <NUM> may be arranged such that each pair of circumferentially adjacent inner magnets <NUM> may be separated by a longitudinal groove <NUM>. In embodiments in which the inner magnets <NUM> are axially aligned and circumferentially aligned, the inner magnets <NUM> may be arranged into axially aligned rings of inner magnets <NUM>. For reference with later figures, the ring <NUM> of inner magnets <NUM> closest to a lower end of the inner sleeve <NUM> may be considered as a first ring <NUM> of inner magnets <NUM>. Similarly, the ring <NUM> of inner magnets <NUM> next to the first ring <NUM> of inner magnets <NUM> may be considered as a second ring <NUM> of inner magnets <NUM>.

The inner magnets <NUM> may be arranged such that the poles of each inner magnet <NUM> are aligned with a circumference of the corresponding ring <NUM> of inner magnets <NUM> to which each magnet belongs. The inner magnets <NUM> may be arranged within each ring <NUM> such that the North pole of one inner magnet <NUM> is facing the North pole of a neighboring inner magnet <NUM>. Similarly, the South pole of one inner magnet <NUM> may be facing the South pole of another neighboring inner magnet <NUM>.

Each inner magnet <NUM> may include a magnetic material. Some example magnetic materials may include, without limitation, ceramic ferrite, neodymium iron boron, samarium cobalt, and aluminum nickel cobalt. The magnetic material may be encased in a non-magnetic material, such as stainless steel, for the physical and chemical protection of the magnetic material.

<FIG> provide a longitudinal cross-sectional view of an embodiment of the debris collection tool <NUM> as assembled in the inactive configuration. As shown in <FIG> and <FIG>, an upper housing <NUM> may have an upper centralizer <NUM>, and may be coupled to a bulkhead <NUM> of a mandrel <NUM>. An adaptor assembly <NUM> may be disposed inside central longitudinal flowbore <NUM> of the debris collection tool <NUM> through the upper housing <NUM> and the mandrel <NUM>. The adaptor assembly <NUM> may include an adaptor extension <NUM> coupled to an adaptor piston <NUM>. The adaptor piston <NUM> may be coupled to an adaptor skirt <NUM>. In some embodiments, the adaptor piston <NUM> and the adaptor skirt <NUM> may be formed as a unitary component. In some embodiments, the adaptor extension <NUM> and the adaptor piston <NUM> may be formed as a unitary component. In some embodiments, the adaptor extension <NUM>, adaptor piston <NUM>, and the adaptor skirt <NUM> together may be formed as a unitary component.

The adaptor piston <NUM> may have one or more seal <NUM> that contacts an inner wall <NUM> of the upper housing <NUM>. The upper housing <NUM> and/or the upper centralizer <NUM> may have one or more port <NUM> that fluidically couples an interior portion <NUM> of the upper housing <NUM> with an exterior of the upper housing <NUM>. The adaptor piston <NUM> may be positioned below the port <NUM>. Thus, the adaptor piston <NUM> may separate the interior portion <NUM> of the upper housing that has a direct fluidic connection with an exterior of the upper housing <NUM> from an activation chamber <NUM> that does not have a direct fluidic connection with an exterior of the upper housing <NUM>.

Still with <FIG> and <FIG>, in <FIG> an adaptor sleeve <NUM> is shown coupled to the adaptor skirt <NUM> of the adaptor assembly <NUM> by a threaded connection <NUM> that allows for adjustment of the relative axial positioning of the adaptor sleeve <NUM> and the adaptor skirt <NUM>. A fastener <NUM> that secures the adaptor sleeve <NUM> to the adaptor skirt <NUM> after adjustment of their relative axial position is shown in <FIG>. The adaptor sleeve <NUM> and adaptor skirt <NUM> may extend into the central longitudinal flowbore <NUM> of the debris collection tool <NUM> at the bulkhead <NUM> of the mandrel <NUM>.

A yoke <NUM> of a linkage <NUM> assembly is shown coupled to the adaptor sleeve <NUM>, and situated in the activation chamber <NUM> of the upper housing <NUM>. In some embodiments, as shown in <FIG>, the yoke <NUM> may be retained by one or more fastener <NUM>. The yoke <NUM> is shown coupled to elongate members <NUM> that extend through secondary bores <NUM> of the bulkhead <NUM>. One or more seals <NUM> between each elongate member <NUM> and each corresponding secondary bore <NUM> inhibits fluid communication through the secondary bores <NUM> into, and out of, the activation chamber <NUM>. As shown in <FIG>, each elongate member <NUM> is coupled to a key <NUM> located in a slot <NUM> formed in the mandrel <NUM>. Each key <NUM> is shown coupled to an inner sleeve <NUM> by projecting into an aperture <NUM>.

In <FIG>, an upper bonnet <NUM> is shown coupled to the bulkhead <NUM> and extending over the slots <NUM> of the mandrel <NUM> and an upper portion of the inner sleeve <NUM>. The upper bonnet <NUM> may be constructed out of a non-magnetic material, such as a stainless steel. Transitioning from <FIG>, an upper shield <NUM> is shown within a lower portion of the upper bonnet <NUM>. In some embodiments, the upper shield <NUM> may be omitted. When present, the upper shield <NUM> may be constructed out of a magnetic material, such as a magnetic grade of steel. In some embodiments, the upper shield <NUM> may be sized to have a length corresponding to a length of a ring <NUM> of inner magnets <NUM>. In some embodiments, the upper shield <NUM> may be sized to have a length that is greater than a length of a ring <NUM> of inner magnets <NUM>. An annular gap between an inner surface of the upper shield <NUM> and an outer surface of the inner sleeve <NUM> may be sized such that the annular gap may accommodate a ring <NUM> of inner magnets <NUM>. When a ring <NUM> of inner magnets <NUM> is radially aligned with the upper shield <NUM>, the upper shield <NUM> may inhibit the transmission of a magnetic field from the ring <NUM> of inner magnets <NUM> through the upper bonnet <NUM>. Thus, magnetic debris will not be prone to accumulate around the upper bonnet <NUM>, thereby mitigating a risk of the debris collection tool <NUM> becoming stuck in a wellbore due to debris accumulation around the upper bonnet <NUM>.

As shown in <FIG>, a cover <NUM> extends from the upper bonnet <NUM> to a lower bonnet <NUM>. The cover <NUM> may be constructed out of a non-magnetic material, such as a stainless steel. In some embodiments, an outer diameter of the cover <NUM> may be less than an outer diameter of the upper bonnet <NUM> and less than an outer diameter of the lower bonnet <NUM>. A lower end of the upper bonnet <NUM>, an upper end of the lower bonnet <NUM>, and the cover <NUM> may define a debris collection zone <NUM>. The debris collection zone <NUM> may thus be recessed with respect to the upper bonnet <NUM> and the lower bonnet <NUM>. Such recessing of the debris collection zone <NUM> enables debris to be accumulated on the cover <NUM> and mitigates a risk of the debris being washed off due to fluid flow around the exterior of the debris collection tool <NUM>. Such recessing of the debris collection zone <NUM> also mitigates a risk of the debris collection tool <NUM> becoming stuck in a wellbore due to debris accumulation around the cover <NUM>.

The lower bonnet <NUM> may be constructed out of a non-magnetic material, such as a stainless steel. A lower shield <NUM> is shown within an upper portion of the lower bonnet <NUM>. In some embodiments, the lower shield <NUM> may be omitted. When present, the lower shield <NUM> may be constructed out of a magnetic material, such as a magnetic grade of steel. In some embodiments, the lower shield <NUM> may be sized to have a length corresponding to a length of a ring <NUM> of inner magnets <NUM>. In some embodiments, the lower shield <NUM> may be sized to have a length that is greater than a length of a ring <NUM> of inner magnets <NUM>. An annular gap between an inner surface of the lower shield <NUM> and an outer surface of the inner sleeve <NUM> may be sized such that the annular gap may accommodate a ring <NUM> of inner magnets <NUM>. When a ring <NUM> of inner magnets <NUM> is radially aligned with the lower shield <NUM>, the lower shield <NUM> may inhibit the transmission of a magnetic field from the ring <NUM> of inner magnets <NUM> through the lower bonnet <NUM>. Thus, magnetic debris will not be prone to accumulate around the lower bonnet <NUM>, thereby mitigating a risk of the debris collection tool <NUM> becoming stuck in a wellbore due to debris accumulation around the lower bonnet <NUM>.

As shown in <FIG>, within the cover <NUM>, and extending from the upper bonnet <NUM> to the lower bonnet <NUM> there may be an outer magnet array <NUM> having one or more ring <NUM> of outer magnets <NUM>. In embodiments in which the outer magnet array <NUM> includes more than one ring <NUM> of outer magnets <NUM>, the rings <NUM> of outer magnets <NUM> may be longitudinally stacked between the upper bonnet <NUM> and the lower bonnet <NUM>. The ring <NUM> of outer magnets <NUM> adjacent to the lower shield <NUM> may be considered as a first ring <NUM> of outer magnets <NUM>. Similarly, the ring <NUM> of outer magnets <NUM> next to the first ring <NUM> of outer magnets <NUM> may be considered as a second ring <NUM> of outer magnets <NUM>. <FIG> illustrates the inner sleeve <NUM> extending over the mandrel <NUM>, through the cover <NUM> and the outer magnet array <NUM>, and into an upper portion of the lower bonnet <NUM>. An inner magnet array <NUM> on the inner sleeve <NUM> is shown positioned within the outer magnet array <NUM>.

In some embodiments, a first ring <NUM> of inner magnets <NUM> may be positioned within the lower shield <NUM>. In some embodiments, the inner magnet array <NUM> may have one ring <NUM> of inner magnets <NUM> additional to the number of rings <NUM> of outer magnets <NUM> of the outer magnet array <NUM>. Hence, a debris collection tool <NUM> may include n rings <NUM> of outer magnets <NUM> and n+<NUM> rings <NUM> of inner magnets <NUM>. In some embodiments, each outer magnet <NUM> of the outer magnet array <NUM> may be adjacent to, and radially aligned with, a corresponding inner magnet <NUM> of the inner magnet array <NUM>. Thus, each outer magnet <NUM> of a first ring <NUM> of outer magnets <NUM> may be radially adjacent to a corresponding inner magnet <NUM> of a second ring <NUM> of inner magnets <NUM>, and so on, such that each outer magnet <NUM> of the last (nth) ring <NUM> of outer magnets <NUM> may be radially adjacent to a corresponding inner magnet <NUM> of the last (n+<NUM>th) ring <NUM> of inner magnets <NUM>.

<FIG> shows a cut-away perspective view of a ring <NUM> of outer magnets <NUM> positioned over a ring <NUM> of inner magnets <NUM>. For clarity, only a single ring <NUM> of outer magnets <NUM> is depicted. Each outer magnet <NUM> may be radially adjacent to, and radially aligned with, a corresponding inner magnet <NUM>. In some embodiments, as illustrated, a radially inward portion of each bridge <NUM> of the ring <NUM> of outer magnets <NUM> may be located in a corresponding longitudinal groove <NUM> of the inner sleeve <NUM>. Therefore, as the inner sleeve <NUM> and inner magnet array <NUM> moves axially with respect to the outer magnet array <NUM>, the interaction between each bridge <NUM> and the corresponding longitudinal groove <NUM> maintains the alignment between individual rows of inner magnets <NUM> and corresponding individual rows of outer magnets <NUM>. In some embodiments, the interaction between each bridge <NUM> and a floor <NUM> of each corresponding longitudinal groove <NUM> may maintain a separation between each outer magnet <NUM> and each corresponding radially adjacent inner magnet <NUM>.

Returning to <FIG>, the mandrel <NUM> extends through the upper bonnet <NUM>, through the inner sleeve <NUM>, and through the lower bonnet <NUM>. A floating piston <NUM> may be contained within an annular space between the lower bonnet <NUM> and the mandrel <NUM>. Seals <NUM>, <NUM> may inhibit the passage of fluid past the floating piston <NUM>. A sealed compartment may be defined by the annular space between an outer surface of the mandrel <NUM> and the inner surfaces of the upper housing <NUM>, the upper bonnet <NUM>, the cover <NUM>, and the lower bonnet <NUM>; the sealed compartment being bounded at an upper end by the seals <NUM> between the elongate members <NUM> and the secondary bores of the bulkhead <NUM>, and at a lower end by the floating piston <NUM>. The sealed compartment may contain a clean fluid, such as a hydraulic oil, so as to facilitate the movement of the inner sleeve <NUM> during operation. During assembly of the debris collection tool <NUM>, the clean fluid may be introduced into the sealed compartment through one or more filling port <NUM> in the upper bonnet <NUM> and/or the lower bonnet <NUM>. Additionally, a filling port <NUM> may be use to evacuate air from the sealed compartment while the clean fluid is introduced into the sealed compartment through another filling port <NUM>.

The annular space between the lower bonnet <NUM> and the mandrel <NUM> may be exposed to a pressure external to the debris collection tool <NUM> through port <NUM>. The floating piston <NUM> may move within the annular space between the lower bonnet <NUM> and the mandrel <NUM> in order to balance a pressure within the sealed compartment with a pressure external to the debris collection tool <NUM>. Further, in <FIG>, the lower bonnet <NUM> may be coupled to a lower housing <NUM>. The mandrel <NUM> may be coupled to the lower housing <NUM>. The lower housing <NUM> may have a lower centralizer <NUM>.

<FIG> show the debris collection tool <NUM> of <FIG> in the activated configuration. The debris collection tool <NUM> may be switched from the inactive to the activated configurations by the application of pressure in the central longitudinal flowbore <NUM> below any present adaptor assembly <NUM>. This may be achieved, for example, by applying pump pressure to a fluid within a workstring to which the debris collection tool <NUM> may be coupled.

With reference to <FIG> and <FIG>, pressure inside the central longitudinal flowbore <NUM> may be communicated between the adaptor sleeve <NUM> and the adaptor skirt <NUM>, and/or between the adaptor skirt <NUM> and the bulkhead <NUM>, to the activation chamber <NUM>. Because of the seals between the elongate member(s) <NUM> and the secondary bore(s) of the bulkhead <NUM>, the pressure in the activation chamber <NUM> may not be communicated through the secondary bore(s) of the bulkhead <NUM>. Pressure in the activation chamber <NUM> acts on one side of the adaptor piston <NUM>. Pressure external to the debris collection tool <NUM>, communicated through the port(s) <NUM> acts on an opposing side of the adaptor piston <NUM>. When a force on the adaptor piston <NUM> resulting from the pressure in the activation chamber <NUM> exceeds an opposing force on the adaptor piston <NUM> resulting from the pressure external to the debris collection tool <NUM>, the adaptor piston <NUM> will experience a net force urging the adaptor piston <NUM> to move longitudinally away from the bulkhead <NUM>. <FIG> shows the adaptor piston <NUM> having moved to a position at which the debris collection tool <NUM> is in the activated configuration.

Still referring to <FIG> and <FIG>, when the adaptor piston <NUM> moves longitudinally, the adaptor extension <NUM> and the adaptor skirt <NUM> may move in the same direction. When the adaptor skirt <NUM> moves longitudinally, the adaptor sleeve <NUM> may move in the same direction. When the adaptor sleeve <NUM> moves longitudinally, the yoke <NUM> of the linkage <NUM> may move in the same direction. When the yoke <NUM> moves longitudinally, the elongate member(s) <NUM> may move in the same direction with respect to the bulkhead <NUM>, and the key(s) <NUM> may move longitudinally within the slot(s) of the mandrel <NUM>. Longitudinal movement of the key(s) <NUM> may cause the inner sleeve <NUM> to move in the same direction.

With reference to <FIG> and <FIG>, longitudinal movement of the inner sleeve <NUM> may move the inner magnet array <NUM> longitudinally with respect to the outer magnet array <NUM>, the upper shield <NUM>, and the lower shield <NUM>. Rotational alignment of the inner magnet array <NUM> with respect to the outer magnet array <NUM> may be maintained at least in part by the bridges <NUM> of the rings <NUM> of outer magnets <NUM> interspersed between the inner magnets <NUM>. Rotational alignment of the inner magnet array <NUM> with respect to the outer magnet array <NUM> may be maintained at least in part by the bridges <NUM> of the rings <NUM> of outer magnets <NUM> being inserted in the longitudinal grooves <NUM> of the inner sleeve <NUM>. Such longitudinal movement of the inner magnet array <NUM> displaces each ring <NUM> of inner magnets <NUM>. Thus, the first ring <NUM> of inner magnets <NUM> is displaced from a location of radial alignment with the lower shield <NUM> to a position whereby each inner magnet <NUM> of the first ring <NUM> of inner magnets <NUM> become radially aligned with a corresponding outer magnet <NUM> of the first ring <NUM> of outer magnets <NUM>. Each ring <NUM> of inner magnets <NUM> may be similarly displaced from radial alignment with one ring <NUM> of outer magnets <NUM> to become radially aligned with an adjacent ring <NUM> of outer magnets <NUM>. However, in some embodiments, the last (n+<NUM>th) ring <NUM> of inner magnets <NUM> may be displaced from radial alignment with the last (nth) ring <NUM> of outer magnets <NUM> to become radially aligned with the upper shield <NUM>.

<FIG> presents a schematic lateral cross-section of the debris collection tool <NUM> to illustrate exemplary juxtapositions of the inner magnets <NUM> and the outer magnets <NUM> in the inactive configuration. <FIG> presents a schematic lateral cross-section of the debris collection tool <NUM> to illustrate an exemplary magnetic field resulting from the arrangement shown in <FIG>.

<FIG> shows a ring <NUM> of outer magnets <NUM> radially aligned with a ring <NUM> of inner magnets <NUM>. Additionally, each outer magnet <NUM> of the ring <NUM> of outer magnets <NUM> is radially aligned with a corresponding inner magnet <NUM> of the ring <NUM> of inner magnets <NUM>. In <FIG>, the North pole of each outer magnet <NUM> is adjacent to, and radially aligned with, the South pole of a corresponding inner magnet <NUM>. Similarly, the South pole of each outer magnet <NUM> is adjacent to, and radially aligned with, the North pole of a corresponding inner magnet <NUM>. Additionally, the North pole of each outer magnet <NUM> is circumferentially adjacent the North pole of a neighboring outer magnet <NUM>, and the South pole of each outer magnet <NUM> is circumferentially adjacent the South pole of a neighboring outer magnet <NUM>. Furthermore, the North pole of each inner magnet <NUM> is circumferentially adjacent the North pole of a neighboring inner magnet <NUM>, and the South pole of each inner magnet <NUM> is circumferentially adjacent the South pole of a neighboring inner magnet <NUM>.

As illustrated in <FIG>, because of the arrangement described above, a magnetic field <NUM> emanating from (for example) the North pole of an outer magnet <NUM> is repelled by the North pole of the circumferentially adjacent neighboring outer magnet <NUM>, but is attracted to the South pole of the radially adjacent neighboring inner magnet <NUM>. Similarly, a magnetic field <NUM> emanating from (for example) the North pole of an inner magnet <NUM> is repelled by the North pole of the circumferentially adjacent neighboring inner magnet <NUM>, but is attracted to the South pole of the radially adjacent neighboring outer magnet <NUM>.

Therefore, the magnetic fields <NUM> may be substantially contained in the areas between circumferentially and radially adjacent magnets. Since these areas contain the bridges <NUM> of the rings <NUM> of outer magnets <NUM>, and the bridges <NUM> may be constructed out of magnetic material, the magnetic fields <NUM> may be concentrated in the bridges <NUM>. Such a concentration of the magnetic fields <NUM> may result in the debris collection tool <NUM> projecting a weak, negligible, or substantially no, magnetic field into the environment immediately external to the cover <NUM>. Therefore, when the debris collection tool <NUM> is in the inactive configuration, very little, or substantially no, magnetic debris may accumulate in the debris collection zone <NUM>.

<FIG> presents a schematic lateral cross-section of the debris collection tool <NUM> to illustrate exemplary juxtapositions of the inner magnets <NUM> and the outer magnets <NUM> in the activated configuration. <FIG> presents a schematic lateral cross-section of the debris collection tool <NUM> to illustrate an exemplary magnetic field resulting from the arrangement shown in <FIG>.

For the purposes of illustration, the ring <NUM> of outer magnets <NUM> in <FIG> is the same ring <NUM> of outer magnets <NUM> in <FIG>. However, because the inner sleeve <NUM> with the inner magnet array has moved longitudinally, the ring <NUM> of inner magnets <NUM> of <FIG> has been replaced by a new ring <NUM> of inner magnets <NUM> that is axially adjacent to the ring <NUM> of inner magnets <NUM> of <FIG>. Thus, if the ring <NUM> of inner magnets <NUM> of <FIG> is the rth ring <NUM> of inner magnets <NUM>, the new ring <NUM> of inner magnets <NUM> of <FIG> would be the r-<NUM>th ring <NUM> of inner magnets <NUM>.

Consistent with the ring <NUM> of inner magnets <NUM> in <FIG>, the North pole of each inner magnet <NUM> in <FIG> is circumferentially adjacent the North pole of a neighboring inner magnet <NUM>, and the South pole of each inner magnet <NUM> is circumferentially adjacent the South pole of a neighboring inner magnet <NUM>. In contrast to <FIG>, however, <FIG> shows that the North pole of each outer magnet <NUM> is adjacent to, and radially aligned with, the North pole of a corresponding inner magnet <NUM>. Similarly, the South pole of each outer magnet <NUM> is adjacent to, and radially aligned with, the South pole of a corresponding inner magnet <NUM>.

As illustrated in <FIG>, because of the arrangement described above, a magnetic field <NUM> emanating from (for example) the North pole of an outer magnet <NUM> is repelled by the North pole of the circumferentially adjacent neighboring outer magnet <NUM>, and is repelled by the North pole of the radially adjacent neighboring inner magnet <NUM>. Therefore, the magnetic fields <NUM> are not substantially contained in the areas between circumferentially and radially adjacent magnets. Instead, the magnetic field <NUM> created by each outer magnet <NUM> may extend from the North pole of the outer magnet <NUM> outward through the cover <NUM> into the environment external to the debris collection tool <NUM>, and return through the cover <NUM> to the South pole of the outer magnet <NUM>. The relative lack of containment of the magnetic fields <NUM> in the areas between circumferentially and radially adjacent magnets may cause the magnetic field <NUM> in the environment external to the debris collection tool <NUM> to be relatively strong compared to when the debris collection tool <NUM> is in the inactive configuration. Therefore, when the debris collection tool <NUM> is in the activated configuration, magnetic items in the environment external to the debris collection tool <NUM> may be attracted to the debris collection zone <NUM>, and magnetic debris may accumulate in the debris collection zone <NUM>.

As shown in <FIG>, a magnetic field <NUM> may pass through the mandrel <NUM>. In some embodiments, the mandrel <NUM> may be constructed out of a magnetic material, and may have a sufficiently large wall thickness such that the magnetic field experienced in the central longitudinal flowbore <NUM> through the mandrel <NUM> may be relatively weak. Hence, a propensity for magnetic particles to accumulate in the central longitudinal flowbore <NUM> through the mandrel <NUM> may be mitigated.

In use, the debris collection tool <NUM> may be coupled to a workstring. In some embodiments, the debris collection tool <NUM> may be coupled to a workstring to which one or more additional tool may be coupled. The additional tool(s) may include, without limitation, any one or more of a cutting tool, a scraping tool, a perforating tool, a drilling tool, a milling tool, a motor, an explosive tool, a jetting tool, a filter tool, a circulation diverting tool, a packer, a packer setting tool, a bridge plug, a bridge plug setting tool, a liner expansion tool, a cementing tool, a pressure testing tool, an inflow testing tool, a pressure surge mitigation tool, a seat for a ball or dart, a catcher for a ball or dart, a fishing tool, a disconnect tool, a data gathering tool, a data recording tool, a telemetry tool, or combination(s) thereof.

The workstring with the debris collection tool <NUM> may be inserted into a wellbore. As shown in <FIG>, the debris collection tool <NUM> may be initially in the inactive configuration upon insertion in the wellbore <NUM>. If present, other tools on the workstring may be actuated in the wellbore <NUM> while the debris collection tool <NUM> is in the inactive configuration. As shown in <FIG>, magnetic particles <NUM> may not accumulate in the debris collection zone <NUM>. The debris collection tool <NUM> may be transitioned to the activated configuration while in the wellbore <NUM>.

As described above, the debris collection tool <NUM> may be transitioned to the activated configuration by the application of pressure in the central longitudinal flowbore <NUM>. Such pressurizing may be achieved by pumping a fluid through the workstring into the central longitudinal flowbore <NUM>. The pressurizing may be assisted by pumping the fluid through a nozzle below the debris collection tool <NUM>, such that the flow of the fluid through the nozzle creates a back pressure that is experienced in the central longitudinal flowbore <NUM>. The pressurizing may be assisted by landing a blocking object, such as a ball or a dart, on a seat below the activation chamber <NUM> of the debris collection tool <NUM>. The seat may be part of the debris collection tool <NUM>, or may be positioned below the debris collection tool <NUM>. The blocking object may substantially obstruct the passage of fluid therearound, and thus further pumping of fluid after the blocking object lands on the seat will increase the pressure in the workstring and in the longitudinal flowbore of the debris collection tool <NUM>.

Once transitioned into the activated configuration, the debris collection tool <NUM> may now attract magnetic particles <NUM> to the debris collection zone <NUM>, as shown in <FIG>. The debris collection tool <NUM> may remain in the activated configuration while other tools on the workstring are actuated. The debris collection tool <NUM> may remain in the activated configuration while the workstring and the debris collection tool <NUM> are retrieved from the wellbore <NUM>.

The debris collection tool <NUM> may be coupled to a controller for use in a wellbore <NUM>. <FIG> shows a controller <NUM> with a debris collection tool <NUM>. The controller <NUM> may be configured to couple to an upper end of the upper housing <NUM> of the debris collection tool <NUM>. A control sleeve (not shown) in the controller <NUM> may be configured to couple to the adaptor extension <NUM> or to the adaptor piston <NUM> of the debris collection tool <NUM>.

In some embodiments, the controller <NUM> may selectively prevent or allow movement of the adaptor sleeve <NUM>, thereby selectively preventing or allowing the debris collection tool <NUM> to transition between inactive and activated configurations. The controller <NUM> may switch between preventing and allowing the debris collection tool <NUM> to transition between inactive and activated configurations upon being triggered. In some embodiments, the controller <NUM> may be triggered by landing a dropped object on a seat, such as per a controller depicted in <CIT>, the disclosure of which is incorporated herein by reference.

In some embodiments, the controller <NUM> may be triggered by telemetry of a signal. The signal may be conveyed to the controller <NUM> by any one of: a RFID tag; electronically through a wire; electromagnetically; acoustically through a fluid, such as a fluid pressure pulse; acoustically through the workstring or a casing of a wellbore <NUM>; fluid flow modulation; workstring manipulation, such as rotation and/or axial movement; or combination(s) thereof. The controller <NUM> may operate similarly to any of the controllers depicted in <CIT>; <CIT>; <CIT>; and <CIT>; the disclosures of which are incorporated herein by reference.

Hence, the debris collection tool <NUM> may be maintained in the inactive configuration by the controller <NUM> even if the debris collection tool <NUM> experiences a pressure in the longitudinal flowbore that otherwise would be sufficient to trigger the debris collection tool <NUM> to transition into the activated configuration. Therefore, the controller <NUM> may prevent premature activation of the debris collection tool <NUM> while other operations (such as cutting, scraping, milling, packer setting, pressure testing, fishing, etc.) are being conducted using the workstring and any other tools coupled to the workstring. When it is desired to activate the debris collection tool <NUM>, the controller <NUM> may be prompted by any of the techniques described above and in the above-cited references to permit upward movement of the adaptor sleeve <NUM>, and any attached components of the adaptor assembly <NUM>. Then, the application of sufficient pressure in the longitudinal flowbore of the debris collection tool <NUM> may activate the debris collection tool <NUM>, as described above.

<FIG> shows a controller <NUM> with the debris collection tool <NUM>. The controller <NUM> may selectively prevent or allow movement of the adaptor sleeve <NUM>, thereby selectively preventing or allowing the debris collection tool <NUM> to transition between inactive and activated configurations. The controller <NUM> may be configured to switch selectively between preventing and allowing the transition of the debris collection tool <NUM> without requiring the use of a blocking object landing on a seat and without requiring the use of telemetry. The controller <NUM> may be configured to couple to the bulkhead <NUM> of the debris collection tool <NUM>. Hence, the upper housing <NUM> and upper centralizer <NUM> may be omitted from the debris collection tool <NUM>.

<FIG> and <FIG> show a longitudinal cross-sectional view of the controller <NUM> of <FIG> together with an upper portion of the debris collection tool <NUM>. <FIG> illustrates components of the controller <NUM> when the debris collection tool <NUM> is in the inactive configuration. <FIG> illustrates components of the controller <NUM> when the debris collection tool <NUM> is in the activated configuration.

Turning to <FIG>, the controller <NUM> may have a top sub <NUM> coupled to a block housing <NUM>. In some embodiments, the top sub <NUM> and the block housing <NUM> may be integrally formed. The block housing <NUM> may be coupled to a piston housing <NUM>. The piston housing <NUM> may include a centralizer <NUM>. The piston housing <NUM> may be coupled to a bottom sub <NUM>. In some embodiments, as shown in <FIG>, the piston housing <NUM> and the bottom sub <NUM> may be integrally formed. The bottom sub <NUM> may be coupled to the debris collection tool <NUM>. As shown in <FIG>, the bottom sub <NUM> may be coupled to the bulkhead <NUM> of the debris collection tool <NUM>.

The piston housing <NUM> may have a piston chamber <NUM>. A control piston <NUM> may be located inside the piston chamber <NUM>. One or more seal <NUM> may inhibit the passage of fluid between the control piston <NUM> and an inner wall of the piston chamber <NUM>. The control piston <NUM> may be positioned proximate to a lower end of the piston chamber <NUM>. A biasing member <NUM>, such as a spring, may inhibit the control piston <NUM> from moving axially away from the lower end of the piston chamber <NUM>. The control piston <NUM> may be coupled to a piston sleeve <NUM> that extends from the control piston <NUM>, through the piston chamber <NUM>, and into the block housing <NUM>. In some embodiments, the control piston <NUM> and the piston sleeve <NUM> may be integrally formed. The control piston <NUM> may be coupled to an extension sleeve <NUM> that extends from the control piston <NUM> into the bottom sub <NUM>. In some embodiments, the control piston <NUM> and the extension sleeve <NUM> may be integrally formed. The adaptor sleeve <NUM> of the debris collection tool <NUM> may be coupled to the extension sleeve <NUM>. The adaptor sleeve <NUM> may be coupled to the extension sleeve <NUM> in a similar manner to the coupling between the adaptor sleeve <NUM> and the adaptor skirt <NUM>, illustrated in <FIG> and <FIG>.

In some alternative embodiments, the adaptor sleeve <NUM> may be coupled to the adaptor extension <NUM>, and the adaptor extension <NUM> may be coupled to the extension sleeve <NUM>. The adaptor sleeve <NUM> may be coupled to the adaptor extension <NUM> in a similar manner to the coupling between the adaptor sleeve <NUM> and the adaptor skirt <NUM>, illustrated in <FIG> and <FIG>.

As illustrated in <FIG>, a central longitudinal flowbore <NUM> of the controller <NUM> may extend from the top sub <NUM>, through the piston sleeve <NUM>, control piston <NUM> and extension sleeve <NUM>, and be fluidically coupled to the central longitudinal flowbore <NUM> of the debris collection tool <NUM>.

As illustrated in <FIG>, because the bottom sub <NUM> of the controller <NUM> is coupled to the bulkhead <NUM> of the debris collection tool <NUM>, the activation chamber <NUM> of the debris collection tool <NUM> is defined at least in part by the bottom sub <NUM> and the bulkhead <NUM>. A bottom side of the control piston <NUM> may be fluidically coupled to the activation chamber <NUM>.

The portion of the piston chamber <NUM> above the control piston <NUM> and between an external surface of the piston sleeve <NUM> and an internal surface of the piston housing <NUM>, may contain a control fluid, such as a hydraulic oil. The piston chamber <NUM> may be bounded at an upper end by a valve block <NUM> of the block housing <NUM>. The valve block <NUM> may separate the piston chamber <NUM> from an upper chamber <NUM> of the block housing <NUM>. A transfer bore <NUM> in the valve block <NUM> may provide a fluid pathway between the piston chamber <NUM> and the upper chamber <NUM>. The transfer bore <NUM> may have a check valve <NUM>. The check valve <NUM> may allow the passage of control fluid from the piston chamber <NUM> to the upper chamber <NUM>, but inhibit the passage of control fluid from the upper chamber <NUM> to the piston chamber <NUM>. A reset bore <NUM> in the valve block <NUM> may provide a fluid pathway between the piston chamber <NUM> and the upper chamber <NUM>. The reset bore <NUM> may have a stop valve <NUM>. The stop valve <NUM> may be adjustable to selectively allow or inhibit the passage of control fluid from the piston chamber <NUM> to the upper chamber <NUM>, and the passage of control fluid from the upper chamber <NUM> to the piston chamber <NUM>. In some embodiments, the stop valve <NUM> may be a removable plug.

The upper chamber <NUM> may contain a balance piston <NUM>. The balance piston <NUM> may be sealed against an inner surface of the block housing <NUM> and an outer surface of the piston sleeve <NUM> that extends through the block housing <NUM>, and therefore separates the upper chamber <NUM> into upper and lower portions. Hence, the transfer bore <NUM> and the reset bore <NUM> of the valve block <NUM> may be fluidically coupled with the lower portion of the upper chamber <NUM>. The block housing <NUM> may have a port <NUM> that allows the pressure of fluid external to the block housing <NUM> to be communicated to the upper portion of the upper chamber <NUM>.

A piston block <NUM> may be coupled to and around the piston sleeve <NUM> within the upper chamber <NUM>. The piston block <NUM> may be configured to move axially as a result of the piston sleeve <NUM> moving axially. The piston block <NUM> may be temporarily retained in a first position by a fastener <NUM>, such as a latch, locking dog, collet, snap ring, shear ring, shear screw, shear pin, or the like. The fastener <NUM> may temporarily secure the piston block <NUM> to the block housing <NUM>. Thus, the piston block <NUM>, piston sleeve <NUM>, control piston <NUM>, and extension sleeve <NUM> may be temporarily inhibited from moving axially. As a result of this, the adaptor sleeve <NUM> may be temporarily inhibited from moving axially, and therefore the debris collection tool <NUM> may be temporarily maintained in the inactive configuration. In some embodiments, the fastener <NUM> may be omitted. Nevertheless, the piston block <NUM>, piston sleeve <NUM>, control piston <NUM>, and extension sleeve <NUM> may be temporarily inhibited from moving axially upward because of a downward force produced by the biasing member <NUM> and the pressure of the control fluid in the piston chamber <NUM>. Hence, in use, when coupled to a workstring, the debris collection tool <NUM> may be maintained in the inactive configuration while the workstring and other tools coupled to the workstring may be operated by fluid pressures that otherwise would transition the debris collection tool <NUM> to the activated configuration. Thus, the debris collection may be selectively transitioned from the inactive configuration to the active configuration.

In order to transition the debris collection tool <NUM> to the activated configuration, an activation pressure may be applied in the central longitudinal flowbore <NUM> of the debris collection tool <NUM>. As described above, pressure applied in the central longitudinal flowbore <NUM> of the debris collection tool <NUM> may be communicated around the adaptor sleeve <NUM> to the activation chamber <NUM>. The pressure in the activation chamber <NUM> may be communicated to the bottom of the control piston <NUM> of the controller <NUM>, resulting in the control piston <NUM> experiencing an upwardly-directed force. This upwardly-directed force may be counteracted by the downward force produced by the biasing member <NUM> and the pressure of the control fluid in the piston chamber <NUM>. In embodiments that include the fastener <NUM>, the upwardly-directed force on the control piston <NUM> is also resisted by the fastener <NUM>. By increasing the pressure in the central longitudinal flowbore <NUM> of the debris collection tool <NUM>, the pressure in the activation chamber <NUM> increases. Thus the pressure on the bottom of the control piston <NUM> of the controller <NUM> increases, and the upwardly-directed force on the control piston <NUM> increases accordingly. When the upwardly-directed force on the control piston <NUM> exceeds the resistance provided by the downward force produced by the biasing member <NUM> and the pressure of the control fluid in the piston chamber <NUM> plus the force required to defeat the fastener <NUM> (if present), such as a shear force, the control piston <NUM> may begin to move upward.

When the control piston <NUM> moves upward, control fluid in the piston chamber <NUM> flows through the transfer bore <NUM>, through the check valve <NUM>, and into the lower portion of the upper chamber <NUM>. The balance piston <NUM> may therefore move upward, and some of the fluid in the upper portion of the upper chamber <NUM> may be vented to an exterior of the controller <NUM> through the port <NUM>. Because the control piston <NUM> moves upward, the piston sleeve <NUM> and piston block <NUM> also move upward. Additionally, the extension sleeve <NUM> moves upward, as does the adaptor sleeve <NUM> of the debris collection tool <NUM> to which the extension sleeve <NUM> is coupled. As described above, this results in the linkage <NUM> moving upward, and thus the inner sleeve <NUM> and inner magnet array <NUM> of the debris collection tool <NUM> also move upward. Hence, the debris collection tool <NUM> transitions from the inactive configuration to the activated configuration.

Per the preceding description, <FIG> shows the controller <NUM> and the upper portion of the debris collection tool <NUM> of <FIG> when the debris collection tool <NUM> has transitioned to the activated configuration. Although the application of pressure in the central longitudinal flowbore <NUM> of the debris collection tool <NUM> is required to transition the debris collection tool <NUM> to the activated condition, the pressure need not be maintained in order to retain the debris collection tool <NUM> in the activated condition. Upon reducing the pressure in the central longitudinal flowbore <NUM> of the debris collection tool <NUM>, the control piston <NUM> may experience a net downward force from the biasing member <NUM> and any residual pressure of the control fluid in the piston chamber <NUM>. However, the control piston <NUM> may be pressure-locked because the control fluid in the lower portion of the upper chamber <NUM> is inhibited from transferring back into the piston chamber <NUM>. The stop valve <NUM> inhibits fluid flow through the reset bore <NUM>, and the check valve <NUM> inhibits fluid flow back into the piston chamber <NUM> through the transfer bore <NUM>. Thus, once the debris collection tool <NUM> has been transitioned to the activated configuration, the controller <NUM> may resist the influence of further operational pressure fluctuations and manipulations, hence maintaining the debris collection tool <NUM> in the activated configuration. Accordingly, an inadvertent transition of the debris collection tool <NUM> back to the inactive configuration, which would result in the release of accumulated particles, may be avoided. Therefore, magnetic debris may accumulate in the debris collection zone <NUM>, and may remain in place while the debris collection tool <NUM> is retrieved from the wellbore <NUM>.

When the controller <NUM> and debris collection tool <NUM> are retrieved from a wellbore <NUM>, the debris collection tool <NUM> may be transitioned back to the inactive configuration to allow for the accumulated debris to be released, and to allow for the debris collection tool <NUM> to be run anew into the wellbore <NUM>. Furthermore, the controller <NUM> may be reset.

As shown in <FIG>, the fastener <NUM> has been defeated, and in this case has become separated into two pieces 1148a and 1148b. The pieces 1148a and 1148b may be removed, and the fastener <NUM> may be replaced once the controller <NUM> has been reset. The piece 1148a remaining in a wall of the block housing <NUM> may be removed by conventional methods. The piece 1148b in the piston block <NUM> may be removed through an access port <NUM>. Alignment between the piston block <NUM> and the access port <NUM> may be maintained by an alignment key <NUM> in a wall of the block housing <NUM> interacting with an alignment slot <NUM> in the piston block <NUM>.

To reset the controller <NUM> and transition the debris collection tool <NUM> back to an inactive configuration, a flow path may be established for the control fluid to travel from the lower portion of the upper chamber <NUM> to the piston chamber <NUM>, thereby releasing the control piston <NUM> from the hydraulic lock. The establishment of the fluid flow path may be achieved by adjustment of the stop valve <NUM> to open the flow path through the reset bore <NUM>. In some embodiments, the stop valve <NUM> may be switched from a closed condition to an open condition. In some embodiments, the stop valve <NUM> may be removed. In some embodiments, the stop valve <NUM> may be partially removed, sufficiently to open the flow path through the reset bore <NUM>. Upon opening the flow path through the reset bore <NUM>, the biasing member <NUM> may push the control piston <NUM> downward, and control fluid may flow through the reset bore <NUM> from the lower portion of the upper chamber <NUM> into the piston chamber <NUM>. When the control piston <NUM> has reached the end of its travel, the stop valve <NUM> may be adjusted to close the flow path through the reset bore <NUM>.

Downward movement of the control piston <NUM> results in downward movement of the piston block <NUM>. When the control piston <NUM> has reached the end of its travel, a replacement fastener <NUM> may be inserted into the piston block <NUM>. In some embodiments, the replacement fastener <NUM> may be omitted. Downward movement of the control piston <NUM> also results in downward movement of the extension sleeve <NUM>, and hence downward movement of the adaptor sleeve <NUM> and the linkage <NUM> of the debris collection tool <NUM>. Thus, the inner sleeve <NUM> and inner magnet array <NUM> of the debris collection tool <NUM> also move downward. Hence, the debris collection tool <NUM> transitions from the activated configuration to the inactive configuration. Debris accumulated around the debris collection tool <NUM> may be cleared from the debris collection tool <NUM>, and the debris collection tool <NUM> may then be run back into the wellbore <NUM>, if required.

Various embodiments have been described of a debris collection tool and other apparatus associated with a debris collection tool. In one embodiment, a debris collection tool may include a mandrel having a longitudinal flowbore therethrough and an inner sleeve disposed around the mandrel. A first array of magnets may be arranged on the inner sleeve. A second array of magnets may be disposed around the inner sleeve. The debris collection tool further may include an adaptor sleeve concentric with the mandrel and a linkage coupling the adaptor sleeve with the inner sleeve.

In another embodiment, a debris collection tool may include a mandrel having a longitudinal flowbore therethrough and an inner sleeve disposed around the mandrel. A first array of magnets may be arranged on the inner sleeve. The first array of magnets may include a plurality of inner magnets disposed around a circumference of the inner sleeve. The inner sleeve may have a longitudinal groove between two adjacent magnets of the first array of magnets. The debris collection tool further may include a second array of magnets disposed around the inner sleeve. The second array of magnets may include an annular arrangement of magnets between a pair of axially spaced end bands and may include a bridge between two circumferentially adjacent magnets. The bridge may be configured to project into the longitudinal groove. In some embodiments, the debris collection tool further may include an adaptor sleeve concentric with the mandrel and a linkage coupling the adaptor sleeve with the inner sleeve.

In another embodiment, a magnet assembly may include first and second annular end bands and may include an annular arrangement of magnets disposed between the first and second annular end bands. The first and second annular end bands may include substantially a non-magnetic material. The magnet assembly further may include a plurality of bridges. Each bridge may be disposed between the first and second annular end bands and between circumferentially adjacent magnets of the annular arrangement of magnets. The bridges may include substantially a magnetic material.

In another embodiment, a controller for a wellbore tool may include a first housing defining a first chamber, and a second housing coupled to the first housing and defining a second chamber. The controller further may include a valve block separating the first and second chambers. A piston may be axially movable within the first chamber. A sleeve may be coupled to the piston, and may extend from the first chamber into the second chamber through the valve block. A fastener may be coupled to sleeve and may be coupled to the second housing. The controller further may include a central longitudinal flowbore through the sleeve and the piston. A first bore through the valve block may fluidically couple an annulus between the sleeve and the first housing with the second chamber, and a check valve may be associated with the first bore. A second bore through the valve block may fluidically couple an annulus between the sleeve and the first housing with the second chamber, and a stop valve may be associated with the second bore.

Claim 1:
A magnetic debris collection tool (<NUM>) for use in a subterranean wellbore, the tool (<NUM>) comprising:
an inner magnetic array (<NUM>) comprising a plurality of axially aligned inner rings (<NUM>), each inner ring (<NUM>) comprising an annular arrangement of inner magnets (<NUM>), and wherein each inner magnet (<NUM>) of an inner ring (<NUM>) is arranged with a north pole facing a north pole of a circumferentially adjacent inner magnet (<NUM>);
an outer magnetic array (<NUM>) comprising a plurality of axially aligned outer rings (<NUM>), each outer ring (<NUM>) comprising an annular arrangement of outer magnets (<NUM>), and wherein each outer magnet (<NUM>) is arranged with a north pole facing a north pole of a circumferentially adjacent outer magnet (<NUM>);
the inner magnetic array (<NUM>) axially movable with respect to the outer magnetic array (<NUM>) between:
a first position in which the inner magnets (<NUM>) of an inner ring (<NUM>) are radially aligned with the outer magnets (<NUM>) of a first outer ring (<NUM>) such that the north pole of each inner magnet (<NUM>) is radially adjacent the north pole of an outer magnet (<NUM>); and
a second position in which the inner magnets (<NUM>) of an inner ring (<NUM>) are radially aligned with the outer magnets (<NUM>) of a second outer ring (<NUM>) such that the north pole of each inner magnet (<NUM>) is radially adjacent the south pole of an outer magnet (<NUM>).