APPARATUS FOR REMOVING AN ITEM FROM A WELLBORE

Abstract: An apparatus for removing an item from a wellbore, said apparatus comprising a bushing (30) having a hollow generally cylindrical shaped body with a bottom, a top and a bore extending from top to bottom, a mandrel (20) extending into said bore, at least one key (31) on one of the mandrel (20) and the bushing (30), a slot system (50) on the other of said mandrel (20) of said bushing (30), said key (31) projecting into said slot system (50), engagement apparatus (18) connected to said mandrel (20) for engaging said item, and milling apparatus (17) connected to the bottom of the bushing (30), wherein said slot system (50) has a top, a bottom, and a series of interconnected slots through which said at least one key (31) is movable, said series of interconnecting slots including exit means for permitting movement of said at least one key (31) out from said slot system (50) thereby permitting free movement of said bushing (30) relative to said mandrel (20).

Description: Apparatus for Removing Material from a Wellbore This invention relates to an apparatus for removing material from a wellbore and, more particularly but not inclusively, is concerned with an apparatus for removing a packer from a wellbore. During the construction, maintenance and repair of oil and gas wells it is often necessary to remove material from the wellbore. Often the material is designed to be removed. However, the release mechanism does not always work and sometimes the item was never intended to be removed. In either case it is important to try and ensure that as much of the item as possible is removed as any debris left in the wellbore can eventually cause serious damage. The present invention provides an apparatus for removing an item from a wellbore, said apparatus comprising a bushing having a hollow generally cylindrical shaped body with a bottom, a top and a bore extending from top to bottom, a mandrel extending into said bore, at least one key on one of the mandrel and the bushing, a slot system on the other of said mandrel and said bushing, said key projecting into said slot system, engagement apparatus connected to said mandrel for engaging said item, and milling apparatus connected to the bottom of the bushing, wherein said slot system has a top, a bottom, and a series of interconnected slots through which said at least one key is movable, said series of interconnecting slots including exit means for permitting movement of said at least one key out from said slot system thereby permitting free movement of said bushing relative to said mandrel. Other features of this invention are set out in Claim 2 et seq. For a better understanding of the present invention reference will now be made, by way of example, to the accompanying drawings, in which: - Fig. 1 is a side view, partially schematic, of one embodiment of an apparatus according to the present invention; Figs. 2A, 3A, 4A, 5A, and 6A are side cross-section views of certain components of the apparatus of Fig. 1 in various positions; and Figs. 2B, 3B, 4B, 5B, and 6B are side views, to an enlarged scale, showing key positions in the slot systems of the apparatus of Fig. 1. Referring now to Fig. 1, an apparatus 10 according to the present invention has a mandrel 20 shear pinned by shear pins 11 to a bushing 30. Keys 31 of the bushing 30 project into a slot system 50 on and extending continuously around an outer surface of the mandrel 20. An engagement apparatus, e.g. a spear 18 (shown schematically) is connected to the lower end of the mandrel 20. The top of the bushing 30 is connected to a pipe 12 (e.g. a wash pipe or wash pipe extension), which in turn is connected to drive sub 9, a downhole motor 16, and a string 14 of coiled tubing. A rotary shoe 17 is connected to the lower end of the bushing 30. The slot system 50 comprises a series of interconnected slots and openings (e.g. as in Fig. 2B) which may be repeated as many times as need to extend around the entire 360° circumference of the mandrel 20 so that key entry into the slot system 50 at any point will effect the desired movement(s). Fig. 2A shows the apparatus 10 in a "running in hole position" with the shear pins 11 in place and not sheared and with the keys 31 in lower branches 51 of the slot system 50. Any fluid in the wellbore is flowing up into and around the mandrel 20 and the string above it as the apparatus is lowered. The apparatus 10 is in this configuration until the packer is contacted. Pre ferably the spear 18 extends out beyond the rotary shoe to engage the packer (not shown) . The spear 18 enters and then engages the packer to be removed from the wellbore. After engagement, the operator "takes the strain", i.e. pulls up on the string 14 to check engagement, but without shearing the shear pins 11. Then the string 14 is pulled upwardly with sufficient force to shear the shear pins 11, freeing the bushing 30 with respect to the mandrel 20. The rotary shoe 17 is dressed with smooth outer diameter (or a rough dressing is ground smooth) and with rough dressing on its lower end and on its lower interior. After picking up on the work string to shear the shear pins 11, the keys 31 first move into upper branches 52 of the slot system 50 as shown in Fig. 3B, and then, as indicated by the downwardly pointing arrows in Fig. 3B, as right hand rotation is applied to the work string (e.g. mechanically as with conventional rotary rigs or hydraulically with the downhole motor 16 in the string 14) and hence to the bushing 30. As the work string is lowered, the keys 31 exit the slot system 50 from exit channels 53 in communication with middle slots 54 (keys 31 upon exit shown in dotted lines in Fig. 3B). Thus the bushing 30 and the string 14 are freed from the mandrel 20, and the pipe 12, bushing 30 and rotary shoe 18 are free to move downward to contact the packer and free to rotate. It is within the scope of this invention to have a single in-out slot system (half the system shown in Fig. 3B) or to have a plurality (two, three, four, five or more) of such in-out configurations, including a continuous series of them extending completely around (360° circumference) a tubular (either on an outside surface thereof or on an inside surface thereof with keys) appropriately correspondingly on an inside surface or outside surface of another member). For each in-out sub system there may be a separate key or only one or two keys may be used no matter how many in-out slot sub systems. If, while milling of the packer, the rotary shoe (or other milling device) becomes worn and needs to be re-dressed with matrix milling material and/or inserts (any known matrix milling material, any known inserts, in any known array, pattern, or combination), the bushing 30 and rotary shoe may be removed by traversing the slot system 50 (see Fig. 5 and discussion about it, below), using single direction, e.g. right hand rotation of the working string (either mechanical or with down- hole motor) so that they are freed from the mandrel 20 for removal from the wellbore. The spear 18 remains engaged in the stuck packer for re-engagement upon reinsertion of the bushing 30. Upon completion of milling of the packer ( in one aspect milling of a slip or slips that maintain the packer in position), the freed packer may fall with the spear 18 and interconnected mandrel 20. As the mandrel 20 falls, the keys 31 on the bushing 30 are directed by guide walls 55 of the channels 53 into the middle slots 54 of the slot system 50 ( see upwardly pointing arrows in Fig. 4B). The keys 31 then move into and are held in upper slots 56, stopping further falling of the packer and catching the packer-spear-mandrel combination. If the packer is loosened, but does not fall, the bushing 30 can be pulled upwardly so the keys 31 reengage the slot system 50. Then the work string is pulled upwardly in an attempt to free the loosened packer by pulling and/or jarring it. Once the packer is free and the bushing 30 is in engagement with the mandrel 20, pulling up on the work string 14 pulls up the bushing-mandrel-spear-packer combination for removal thereof from the wellbore. Figs. 4 and 5 illustrate the release of the bushing 30 above the slot system 50, e.g. for removal of the bushing 30 to replace the rotary shoe 18. The keys 31 are moved from a position in the upper slots 56 by applying single direction, e.g. right hand, torque to the work string (either mechanically or with a downhole motor) while lowering it, thus moving the keys as shown by the downwardly pointing arrows in Fig. 5B into intermediate slots 57. Slacking off on the work string and sensing "down weight" indicates that the keys 31 are in the slots 57. By "down weight" is meant that when the string is lowered to place the keys in the slots 57, if the packer is still stuck, continued lowering of the string forces the packer to support some weight ("down weight" ) of the string and the surface weight indicator shows a reduction in string weight supported from the surface. As shown in Fig. 6B, while still holding the right hand torque, the work string is raised which moves the keys 31 into side slots 58 and from there out top exit channels 59, thus freeing the bushing 30 and rotary shoe 18 from the mandrel 20 for removal from the wellbore. Without applying any torque, the bushing 30 and a new or redressed rotary shoe 18 can be reinstalled, traversing the slot system 50. When the keys 31, moving downwardly, contact the top exit slots 59, the slot shape moves the keys into the side slots 58 and continued downward movement coupled with the slot shape at the bottom of the slots 58 moves the keys 31 into the intermediate slots 57. Then picking up on the work string moves the keys 31 up and the slot moves the keys into the upper slots 56. Lowering the work string at this point moves the keys 31 downwardly with respect to the slot system 50 so that they exit through the bottom exit channels 53 so milling can commence. This may all be done without the application of torque to the work string. This is desirable in embodiments using a mud motor since left hand (or multi-directional) torque cannot be applied with a mud motor. The various slot walls are at angles so that the slot walls themselves apply leftward force on the keys to produce the desired manipulation of and movement through the slot system 50. It is to be understood that what is described above is an unidirectional system, i.e. only right hand movement or torque/rotation is used; but it is within the scope of this invention to configure the system, again unidirectionally, so that only left hand movement or torque/rotation is used (e.g. if a mud motor was used that was designed to rotate to the left) 1, 2, 3, 4, 5, or more keys 31 may be used. It is to be understood that it is within the scope of this invention to use the apparatus 10 with a conventional work string rotated by a rotary table ( in which case the rotary shoe may be installed without applying torque, but using upward/downward movement of the work string only with lateral motion effected by the slots of the slot system itself. In addition to use of the system 10 to retrieve a packer, it may be used to "fish" any device or item from a wellbore. In one aspect the apparatus 10 as described above and other apparatus according to the present invention can engage a "fish" or a packer to be removed, mill and/or loosen it, free it, and remove it in a single trip into a wellbore. In other aspects, such a removal is effected with one or more intermediate steps to remove a milling device (while the fish or packer is still engaged by an engagement tool such as a spear or overshot) to redress it or replace it. In one method of operating an apparatus according to the present invention ( an apparatus using a rotary table and a typical rig set-up with a kelly and a work string made up of drill pipe), an operator, before lowering the work string, ensures that sufficient kelly is available above the rotary table to enable engagement with a fish in the wellbore while still having sufficient kelly for releasing from the system's outer bushing and milling over the fish. In the event there is premature engagement with the fish, engagement is completed and then the bushing is released. The apparatus is then withdrawn up hole to remove a section of drill pipe. Upon final complete engagement with the fish, the bushing is released from the mandrel by pick-up on the work string with the required over-pull to shear the shear pins (e.g. shear pins 11). Then an additional over-pull (e.g. but not limited to an overpull) 10,000 pound is applied to assure attachment of the mandrel and bushing. While holding right hand torque, the work string is lowered so that the keys exit the slot system. At this point the bushing can be rotated. The work string is lowered further until the rotary shoe makes contact with a top of the fish. The work string is then picked up once contact is made with the fish establishing the location of the fish. Then surface pumps are started to establish fluid circulation down to and out from the rotary shoe (or other mill(s)) for cuttings, the work string is rotated to the required RPM's for milling, and weight is applied on the rotary shoe to mill over the fish. When the fish is free, the work string is pulled out of the hole with the fish. In certain preferred embodiments sufficient spacing is available between the catching device (e.g. a spear, taper tap, etc) and the bottom of the rotary shoe so that the catching device is operable and there is sufficient clearance to rotate the shoe above the fish with the keys of the bushing below the slot system of the mandrel; the inside diameter of the rotary shoe is large enough to pass over the catching device; the inside diameter of the keys on the bushing do not bump up on the catching device; and enough space is below the bushing to cover the total length of the fish being milled over. During milling with the apparatus 10, fluid (e.g. drilling mud, or other known wellbore fluids) is pumped down the work string, through the wash pipe and through the bushing 30 to the rotary shoe (or other mill) 18 to circulate cuttings from the wellbore and to remove cuttings and debris from the shoe-packer interface.

Claims: CLAIMS 1. An apparatus for removing an item from a wellbore, said apparatus comprising a bushing ( 30) having a hollow generally cylindrical shaped body with a bottom, a top and a bore extending from top to bottom, a mandrel (20) extending into said bore, at least one key (31) on one of the mandrel ( 20 ) and the bushing ( 30) , a slot system ( 50 ) on the other of said mandrel ( 20 ) and said bushing (30), said key (31) projecting into said slot system (50), engagement apparatus (18) connected to said mandrel (20) for engaging said item, and milling apparatus (17) connected to the bottom of the bushing (30), wherein said slot system (50) has a top, a bottom, and a series of interconnected slots through which said at least one key (31) is movable, said series of interconnecting slots including exit means for permitting movement of said at least one key (31) out from said slot system (50) thereby permitting free movement of said bushing (30) relative to said mandrel ( 20 ) . 2. An apparatus as claimed in Claim 1, wherein the at least one key (31) is two spaced-apart keys. 3. An apparatus as claimed in Claim 1 or 2, wherein the exit means includes at least one top opening ( 59 ) in the slot system (50) for an exit of the at least one key (31) from the top of the slot system (50) and at least one bottom opening ( 53 ) for an exit of the at least one key (31) from the bottom of the slot system (50). 4. An apparatus as claimed in Claim 1, 2 or 3, wherein the engagement apparatus (18) is engageable with the item while the bushing (30) is disengaged from the mandrel (20) to remove the milling apparatus from the wellbore. 5. An apparatus as claimed in Claim 3, wherein the at least one key (31) is movable through the slot system ( 50 ) so that the bushing ( 30 ) can be lowered below and beyond the slot system ( 50 ) to bring the milling apparatus ( 17 ) into contact with the item for milling the item while the engagement apparatus (18) holds the item. 6. An apparatus as claimed in any preceding claim, wherein the milling apparatus is a rotary shoe ( 17) . 7. An apparatus as claimed in any preceding claim, wherein the engagement apparatus is a wellbore spear (18). 8. An apparatus as claimed in any of Claims 1 to 6, wherein the engagement apparatus is a wellbore overshot. 9. An apparatus as claimed in any preceding claim, wherein the bushing (30) is shear pinned to the mandrel (20) with at least one shear pin (11) and the bushing (30) is selectively releasable from the mandrel (20) by shearing the at least one shear pin (11). 10. An apparatus as claimed in any preceding claim, wherein the at least one key (31) is sized and disposed so that an item falling within the engagement apparatus (18) engaged therewith is stopped by the at least one key (31) entering the slot system (50) of the bushing (30) as the mandrel (20) moves down with the falling item. 11. An apparatus as claimed in any preceding claim, wherein the at least one key (31) is so disposed and the slot system (50) is so configured that the slot system (50) can hold the at least one key (31) so that an engaged item may be jarred by impacting the apparatus. 12. An apparatus as claimed in any preceding claim, wherein the slot system (50) is configured so that the bushing (30) is removable therefrom without applying torque to an item engaged by the engagement apparatus (18). 13. An apparatus as claimed in any preceding claim, wherein the bushing, having been removed from the wellbore, is re-insertable thereinto to traverse the slot system (50) without applying torque to the packer to again mill the item. 14. An apparatus as claimed in any preceding claim, further comprising a downhole motor (16) interconnected with the bushing (30) , and wherein the milling apparatus ( 17 ) is rotatable by the downhole motor (16). 15. An apparatus as claimed in any preceding claim, wherein the slot system (50) is a continuous system extending around the entire outer circumference of the mandrel ( 20 ) . 16. An apparatus as claimed in any preceding claim, further comprising a string of coiled tubing extending into the wellbore, and the bushing (30) interconnected with the coiled tubing string. 17. An apparatus as claimed in any preceding claim, further comprising the bushing (30) and mandrel (20) each having a fluid flow bore therethrough for the pumping of fluid down to and out from the milling apparatus (17) to facilitate removal of milled cuttings from the wellbore. 18. A slot system for a wellbore tool, the slot system comprising at least one intermediate slot through which a key is movable, .a top opening in communication with the at least one intermediate slot so that the key is movable into the top opening and from thence into the at least one intermediate slot, and a bottom opening in communication with the at least one intermediate slot so that the key is movable from the intermediate slot into the bottom opening and from thence out from the slot system. 19. The slot system of Claim 18 wherein the at least one intermediate slot is a series of a plurality of interconnected slots. 20. The slot system of Claim 18 or 19 wherein the plurality of interconnected slots includes at least one slot for holding the key so that an item to which the key is connected is able to pick up a tool having the slot system. 21. The slot system of Claim 18, 19 or 20, wherein the plurality of interconnected slots includes at least one slot for holding the key so that an item to which the key is connected can push down on the slot system to push down on a tool having the slot system. 22. The slot system of Claim 18, 19, 20 or 21, wherein the tool has a circumferential surface and the slot system is a continuous slot system disposed around the circumferential surface. 23. The slot system of any of Claims 18 to 22, wherein the key is connected to a wellbore device and the key is movable through the slot system without applying torque to the device. 24. The slot system of any of Claims 18 to 23, wherein the key is connected to a wellbore device and the key is movable through the slot system by moving the device up and down for longitudinal movement and with slots of the plurality of interconnected slots configured to effect lateral movement of the device. 25. A method for retrieving a packer secured in a wellbore, the method comprising introducing an apparatus as claimed in Claim 1 into the wellbore, releasing the mandrel (20) from the bushing (30), engaging the packer with the engagement apparatus (18), releasing the bushing from the mandrel, moving the at least one key through the slot system, moving the milling apparatus into contact with the packer, rotating the bushing to rotate the milling apparatus to mill the packer, engaging the at least one key in the slot system, and pulling up on the packer to remove the packer from the wellbore. 26. The method of Claim 25 further comprising jarring the packer prior to pulling up on it. 27. The method of Claim 26 further comprising with the packer engaged by the engagement apparatus (18), lifting the bushing (30) and milling apparatus (17) so the at least one key (31) traverses through the slot system ( 50 ) , and removing the bushing (30) and milling apparatus (17) from the wellbore. 28. The method of Claim 27, wherein the bushing and milling apparatus are removed from the wellbore without applying torque to the packer. 29. The method of Claim 28 or 29, further comprising reintroducing the bushing and milling apparatus into the wellbore, traversing the at least one key (31) through the slot system ( 50 ) , and again milling the packer. 30. The method of Claim 29 wherein the bushing and milling apparatus are reintroduced without applying torque to the packer. 31. The method of Claim 26 further comprising rotating the bushing (30) with a downhole motor (16) in a string (14) connected to the bushing (30). 32. The method of Claim 31 further comprising the string (14) comprising coiled tubing. 33. The method of Claim 26 wherein the bushing (30) and mandrel ( 20 ) each have a fluid flow bore therethrough for the pumping of fluid down to and out from the milling apparatus (17) to facilitate removal of milled cuttings from the wellbore, wherein the bushing (30) is connected to a string (14) extending to a surface pump, and the method further comprises pumping fluid through the string (14), to the bushing (30), and to and out from the milling apparatus (17) during milling to facilitate removal of milled cuttings from the wellbore.

Inventors: WRIGHT RALPH DAVID, WRIGHT, RALPH, DAVID
Applicants: LUCAS BRIAN RONALD, WEATHERFORD LAMB, LUCAS, BRIAN, RONALD, WEATHERFORD/LAMB, INC.
Application year: 1998
Main classification: E21B31
IPC codes: E21B23, E21B31