WELL TOOL

Abstract

A well tool for removing metal debris from a well bore has a magnet element, an anti-torque anchor, a debris removal unit, a debris container and a first connecting end for a rotatable well string. The magnet element has a cylinder-shaped housing. The removal unit has a helix-shaped longitudinal guide element arranged on the housing. The anchor is connected to the housing or the guide element such that actuation of the anchor during use will prevent rotation of the housing or the guide element, respectively, relative the well-bore. The container has an opening at the end of the housing. The housing and the guide element are rotatable relative each other, and configured such that metal debris accumulating on the housing during use is guided by the guide element towards the opening of the container when the anchor is actuated and the first connecting end is rotated.

Claims

1. A well tool for removing metal debris from a well bore, comprising a magnet element, an anti-torque anchor, a debris removal unit, a debris container and a first connecting end for a rotatable well string, wherein the magnet element comprises a cylinder-shaped housing having a first end and a second end; the debris removal unit comprises a helix-shaped longitudinal guide element arranged around the cylinder-shaped housing; the anti-torque anchor is operably connected to the cylinder-shaped housing or the helix-shaped longitudinal guide element, such that actuation of the anti-torque anchor during use will prevent rotation of the cylinder-shaped housing or the helix-shaped longitudinal guide element, respectively, relative the well-bore; and the debris container comprises an opening arranged at the second end of the cylinder-shaped housing, wherein the cylinder-shaped housing and the helix-shaped longitudinal guide element are rotatable relative each other around a centerline of the well tool, and configured such that metal debris accumulating on the cylinder-shaped housing during use is guided by the helix-shaped longitudinal guide element towards the opening of the debris container when the anti-torque anchor is actuated and the first connecting end is rotated.

2. The well tool according to claim 1, wherein the cylinder-shaped housing or the helix-shaped longitudinal guide element which is not operably connected to the anti-torque anchor is operably connected to the first connecting end, such that rotational movement of the first connecting end is transferred to the cylinder-shaped housing or the helix-shaped longitudinal guide element, respectively.

3. The well tool according to claim 1, wherein the anti-torque anchor comprises a sleeve assembly having multiple anchoring devices, each anchoring device may be actuated from a first position to a second position, in the second position the anchoring device is radially extended relative the first position such that the multiple anchoring devices may be in contact with a wall of the well bore when actuated during use.

4. The well tool according to claim 3, wherein each of the anchoring devices comprises a roller device arranged to be in contact with a wall of the well bore when the anchoring devices are in the second position, the roller device features an axis of rotation substantially perpendicular to a centerline of the well tool.

5. The well tool according to claim 3 wherein each of the anchoring devices comprises at least one arm being pivotably connected to the sleeve assembly and operably connected to a piston, such that actuation of the piston will move the anchoring device into the second position.

6. The well tool according to claim 5, wherein the at least one arm is operably connected to a spring, the spring biasing the anchoring devices towards the first position.

7. The well tool according to claim 5, wherein the piston comprises an elastic element for interaction with the at least one arm, preferably the elastic element is a leaf spring.

8. The well tool according to claim 1, wherein the anti-torque anchor is connected to the debris removal unit by at least one shear bolt.

9. The well tool according to claim 1, comprising at least one tube element aligned around the centerline of the well tool and extending through the anti-torque anchor and the cylinder-shaped housing.

10. The well tool according to claim 9, wherein the first connecting end is arranged at one end of the at least one tube element.

11. The well tool according to claim 9, comprising a central bore made up of the at least one tube element.

12. The well tool according to claim 11, wherein the first connecting end is in fluid communication with the central bore.

13. The well tool according to claim 5, wherein the piston is actuated by drilling mud from the central bore.

14. The well tool according to claim 13, wherein the at least one tube element comprises at least one radial through-bore fluidly connected to a hydraulic chamber in the sleeve assembly, the hydraulic chamber arranged to provide hydraulic pressure to actuate the piston.

15. A method of removing metal debris from a well bore, comprising the steps of: providing a well tool according to claim 1; connecting a rotatable well string to the first connecting end: lowering the well tool into the well bore; actuating the anti-torque anchor; and rotating the well string to rotate the cylinder-shaped housing or the helix-shaped longitudinal guide element around a centerline of the well tool, such that metal debris accumulating on the cylinder-shaped housing is guided by the helix-shaped longitudinal guide element towards the opening of the debris container.

16. The method according to claim 15, wherein the anti-torque anchor is actuated by providing pressurized drilling fluid to the first connecting end.

17. The well tool according to claim 2, wherein the anti-torque anchor comprises a sleeve assembly having multiple anchoring devices, each anchoring device may be actuated from a first position to a second position, in the second position the anchoring device is radially extended relative the first position such that the multiple anchoring devices may be in contact with a wall of the well bore when actuated during use.

18. The well tool according to claim 4, wherein each of the anchoring devices comprises at least one arm being pivotably connected to the sleeve assembly and operably connected to a piston, such that actuation of the piston will move the anchoring device into the second position.

19. The well tool according to claim 6, wherein the piston comprises an elastic element for interaction with the at least one arm, preferably the elastic element is a leaf spring.

20. The well tool according to claim 10, comprising a central bore made up of the at least one tube element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Embodiments of the present invention are described in detail by reference to the attached drawings:

[0070] FIG. 1 is a perspective view of a first exemplary well tool according to the invention.

[0071] FIG. 2 is a perspective view of detail A of the well tool in FIG. 1.

[0072] FIG. 3 is a cross-sectional view of the well tool in FIG. 1, the cross-section is along the centreline of the well tool.

[0073] FIG. 4 is an enlarged view of detail B in FIG. 3.

[0074] FIG. 5 is an enlarged view of detail C in FIG. 3.

[0075] FIG. 6 is an enlarged view of detail D in FIG. 3.

[0076] FIG. 7 is an enlarged view of the well tool section shown in FIG. 4, wherein the anti-torque anchor is actuated.

[0077] FIG. 8 is a side view of a second exemplary well tool according to the invention.

[0078] FIG. 9 is a sectional view of detail E in FIG. 8.

[0079] FIG. 10 is an enlarged view of detail F in FIG. 9.

[0080] FIG. 11 is a side view of the anchor used in the well tool in FIG. 8.

[0081] FIG. 12 is a sectional view of the anchor in FIG. 11.

[0082] FIG. 13 is an enlarged view of detail G in FIG. 12.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0083] The present invention provides a tool for removal of metal debris from a well, for instance debris lodged in, or in the vicinity of, a BOP. An exemplary embodiment of such a tool is described below with reference to the attached drawings.

[0084] A perspective view of a tool 1 according to the present invention is shown in FIG. 1 and an enlarged detailed view of the section of the tool comprising an anti-torque anchor is shown in FIG. 2.

[0085] FIG. 3 is a cross-sectional view of the well tool along the centreline C.

[0086] The well tool features a magnet element 2 for attracting metal debris, an anti-torque anchor 5, a debris removal unit 3, a debris container 6, a first connecting end 16 suitable for connection to a rotatable well string, and a second connecting end 33. The first connecting end may also be connected to a rotatable well string via a lower end of any other suitable well tool as long as a rotational movement may be provided to the connecting end. The second connecting end 33 may be connected to any suitable auxiliary well tool, such as a milling tool, if required.

[0087] The magnet element 2 have a cylinder-shaped housing 10 having a first end 7 and a second end 8. In the present embodiment, the cylinder-shaped housing 10 comprises multiple magnets 11, see FIGS. 4 and 5, embedded below the surface 12 of the housing. The magnets provide the required magnetic field for attracting metal debris. The magnetic field may be provided by any type of magnet assembly suitable for being embedded in or below the surface of the cylinder-shaped housing.

[0088] The debris removal unit 3 features a scrape 4 (i.e. a helix-shaped longitudinal guide element) arranged around the cylinder-shaped housing 10. The scrape 4 is arranged around and coaxial with the cylinder-shaped housing 10. An inner surface of the scrape (i.e. the surface turned towards a circumferential surface of the cylinder-shaped housing 10) is slightly spaced (0.1-0.5 mm) from a circumferential surface of the housing 10. The scrape 4 is preferably made in non-magnetic stainless steel, i.e. a suitable type of austenitic stainless steel.

[0089] The cylinder-shaped housing 10 and the scrape 4 is rotatable relative to each other around a centreline C of the well tool, such that metal debris accumulating on the cylinder-shaped housing 10 during use may be guided by the scrape 4 towards the opening 9 of the debris container 6 when the anti-torque anchor 5 is actuated and a well string connected to the connecting end is rotated.

[0090] An end section 13 of the magnet element has no, or a weakening, magnetic field in the direction of the second end 8 allowing for discharge of metal debris into the debris container 6 via an opening 9 arranged at the second end 8 of the cylinder-shaped housing 10. To ensure that most or all of the metal debris enters the debris container, the whole end section 13 is arranged inside the debris container, i.e. below the opening 9 of the debris container 6 when the well tool is vertically arranged.

[0091] The anti-torque anchor 5 is connected to the scrape 4, such that actuation of the anti-torque anchor during use will rotationally fix the scrape 4 relative a well-bore in which the well tool is run. The anti-torque anchor comprises a sleeve assembly 15 having multiple anchoring devices 19. Each anchoring device features an arm 22 being pivotably connected to the sleeve assembly at a first end and connected to a wheel 20 (i.e. a wall-contacting portion or a roller device) at a second end. The arm 22 (or wheel 20) is biased into a first position by a spring and operably connected to an annular piston, such that actuation of the piston will move the wheel 20 from the first position to a second position, see FIGS. 4 and 7. The second position is radially extended relative the first position such that the wheels of the multiple anchoring devices may be brought into contact with the wall of a well bore during use. The wheels 20 ensure that rotation of the scrape is prevented when a well string connected to the connecting end is rotated, while at the same time allowing the well tool to be moved in a vertical direction within the well bore.

[0092] Thus, the cylinder-shaped housing 10 will rotate relative to the scrape 4 when the rotary sleeve is in motion. In use, the relative rotary motion between the scrape 4 and the cylinder-shaped housing 10 will cause the metal debris, attracted to and accumulated on the magnetic element, to be pushed towards and into the debris container 6. In this way, the strength of the magnetic field of the magnetic element will not be weakened over time due to accumulated metal debris, and it is therefore not required to bring the well tool topside for intermediate discharge/removal of metal debris until the operation is finished. Transport of the metal debris into the debris container 6 is further improved by having the debris container fixed to the cylinder-shaped housing 10, such that the debris container 6 rotates relative the scrape 4. The latter solution minimizes the formation of metal debris plugs or nesting at the opening 9 of the debris container.

[0093] Optional features of the magnet element 2, the scrape and the debris container are disclosed in WO 2016/155852 A1, and such features are hereby incorporated by reference.

[0094] In the present embodiment, the well tool 1 comprises a central bore 25 made up of multiple tube elements 17a-d (or pipes) which are coaxially arranged with the anti-torque anchor, the cylinder-shaped housing 10, the scrape 4 and the debris container 6. The multiple tube elements are rigidly interconnected and will corotate around the centreline C of the well tool with a rotating well string connected to the connecting end.

[0095] In other embodiments, it is envisaged that a single tube may provide the central bore. However, the solution of having multiple tube elements is preferred as it facilitates manufacture, assembly and repair of the well tool.

[0096] The tube element 17a, extending through the sleeve assembly of the anti-torque anchor, has radial through-bores 18 fluidly connected to a hydraulic chamber 14 arranged at one end of a piston assembly 23a, 23b (i.e. a piston). The piston assembly comprises a first piston element 23a in contact with the arms 22 and a second piston element 23b in contact with the hydraulic chamber 14. The first and the second piston element are separated by a fluid-filled chamber 29 providing a dampening effect. During use of the well tool 1, pressurized drill fluid or mud enters the hydraulic chamber 14 and the piston assembly 23a, 23b is forced against the arms 22 of the anchoring devices 19. In this embodiment, the piston element 23a features an inclined surface 26 which interacts with a cooperating inclined surface 27 on the arm 22. The interaction of the cooperating inclined surfaces pushes the end of the arm featuring the wheel 20 into a radially extended position, i.e. into the second position, see FIG. 7. In the second position, the wheel is in contact with the wall of the well bore.

[0097] The sleeve assembly 15 is connected to the scrape 4 by bolts 21. By use of slide bearings 30, thrust bearings 31 and suitable seals 32 arranged between the sleeve assembly 15 and the tube element 17a, the sleeve assembly and the scrape are free to rotate relative the tube element 17a and the cylinder-shaped housing 10.

[0098] The debris container 6 is rigidly connected to the tube element 17d extending through an end section of the debris container 6 via a connecting sleeve 28.

[0099] A second exemplary well tool 1′ is shown in FIGS. 8-10 and the anchor section of the well tool shown separate in FIGS. 11-13.

[0100] The well tool 1′ in FIGS. 8-10 comprises the same main technical features, and functions in the same manner, as the well tool 1 in FIGS. 1-7. Identical reference numbers are used for features being in common for the two exemplary well tools.

[0101] A side view of the well tool is shown in FIG. 8 and a sectional view of the anchor section, i.e. detail F, is shown in FIG. 9. In view of the first exemplary well tool, the second exemplary well tool comprises two distinguishing technical features.

[0102] The first distinguishing feature is shown in FIGS. 9 and 10. The debris removal unit 3, including the scrape 4, is connected to the anti-torque anchor 5 via shear bolts or pins 34′,34″. Shear bolts or pins are designed to provide a clean break when subjected to shear forces extending a set value. The purpose of having the scrape 4 connected to the anti-torque anchor 5 in this manner is to ensure that the well tool is not unnecessarily damaged if the scrape 4 becomes stuck or the rotational movement between the scrape 4 and the cylinder-shaped housing 10 is prevented during use. Without the shear bolts/pins, the collateral damage to the anti-torque anchor and other parts of the well tool may be substantial if the scrape 4 is stuck.

[0103] The second distinguishing feature is shown in FIGS. 12 and 13. In the second exemplary well tool, the piston 23a, used to move the wheel 20 on the arm 22 of the anti-torque anchor 5 into the second position as described above, features a leaf spring 35 at the end of the piston 23a which interacts with the arms 22. The leaf spring 35 ensures that the force by which the wheels 20 is pushed against the wall of a well bore casing does not exceed a maximum value. The maximum value may be set by selecting a leaf spring 35 having a desired spring constant and displacement. The feature of having a leaf spring 35 on the piston 23a may be advantageous when the well tool 1′ is used together with a hydraulic whipstock for deflecting the direction of the well tool. Hydraulic whipstocks often require a hydraulic pressure of about 220 bars to be set within the well bore, and the resulting pressure on the wheels 20 of the anti-torque anchor 5 may be too high, e.g. causing damage to the well bore casing. In situations wherein a mechanical whipstock is used, the hydraulic pressure may be held at a lower level and a leaf spring is not necessarily required. Although the use of leaf springs is believed to be the most functional solution, in other embodiments the leaf springs may be replaced by alternative elastic elements, such as a plate supported by coil springs or similar assemblies. In the second exemplary embodiment, the arm 22 comprises a first interacting surface 36 arranged to abut against a second interacting surface 37 on the sleeve assembly 15 when the arm is in the second position, i.e. preventing the arm from extending beyond the second position. Having the radial extent obtained in the second position restricted by the interacting surfaces 36,37 is advantageous in particular when the well tool is used together with an hydraulic whipstock.

[0104] Specific solutions for extending the anchoring devices 19 is shown in connection with the exemplary well tools in FIGS. 1-13. However, based on the present disclosure, the skilled person would easily recognize numerous alternative solutions for obtaining a hydraulic, or even electric, actuation of the anchoring devices.

[0105] In the exemplary well tools of FIGS. 1-13, the cylinder-shaped housing 10 is rotated by use of a rotatable well string connected to the first connecting end 16, while the surrounding scrape 4 is rotatably fixed by being connected to the anti-torque anchor, thus obtaining a rotational movement between the cylinder-shaped housing 10 and the scrape 4. In other embodiments, the rotational movement may be obtained by an opposite solution, i.e. rotation of the scrape while the cylinder-shaped housing is fixed. The latter effect may for instance be obtained by having an anti-torque anchor arranged at the debris container 6 to rotatably fix the debris container 6 and the cylinder-shaped housing relative a well bore and a tube element extending through the well tool, and by having the connecting end operably connected to the scrape. The anti-torque anchor may for instance be incorporated in the connecting sleeve 28. In this manner, a rotating well string will cause the scrape to rotate relative both a well bore and the cylinder-shaped housing providing the same effect as in the exemplary well tool.