GB2466565A

GB2466565A - Actuator assembly for tubular expansion

Info

Publication number: GB2466565A
Application number: GB0922082A
Authority: GB
Inventors: Britt O Braddick
Original assignee: TIW Corp
Current assignee: TIW Corp
Priority date: 2008-12-23
Filing date: 2009-12-17
Publication date: 2010-06-30
Also published as: CA2688731A1; NO20093572L; US20100155082A1; GB0922082D0

Abstract

A hydraulically powered downhole tool includes a tool mandrel 20, a plurality of pistons 26 each axially movable relative to the tool mandrel and mechanically connected by an outer sleeve 24 exterior of the tool mandrel. A plurality of mandrel sections and a plurality of outer sleeve sections each have a lower end for interconnection with an upper end of a corresponding member. A retainer 28 is provided for supporting each outer sleeve section above a respective lower sleeve section allowing assembly of the mandrel sections. Slips (56, fig 3) supported by the outer sleeve 24 temporarily fix the outer sleeve in the well. The mandrel can be secured to an expander (48, fig 4). The mandrel may have an inner bore 22 which supplies the pistons with hydraulic fluid. A second independent claim concerns the assembly having a second plurality of pistons connected to the mandrel.

Description

ACTUATOR ASSEMBLY FOR TUBULAR EXPANSION

The present invention relates to an actuator assembly for positioning in a well to actuate a downhole tool. More particularly, this invention relates to a hydraulically powered actuator assembly for suspending in the well from a workstring and producing high forces suitable for radially expanding a downhole tubular.

Various types of downhole actuators are used for operating specific downhole equipment in a well. Actuators may be hydraulically powered or electrically powered, or may be powered from axial or rotational forces transmitted to the actuator by a workstring. Some downhole actuators are powered by a pyrotechnic charge.

Various types of tools have been proposed for expanding a solid tubular downhole. Many of these tools utilize an expander which is moved axially through the tubular and is powered by hydraulic pressure in the tubular behind the expander. One of the problems with this technique is that the expanded tubular is inherently subject to high fluid pressure as the expander moves axially through the tubular. Leaks in the expanded tubular thus decrease the effectiveness of the technique, and the possibility of leaks reduces the recommended fluid pressure since there is a risk that a leak may prevent movement of the expander. If a leak prevents further movement of the expander, limited options are available to circumvent the problem, and the well may need to be abandoned.

Some tools have used hydraulically actuated expanders with fluid power being supplied to the actuator by a workstring separate from the tubular being expanded. As disclosed in U.S. Patent 6,763,893, 6,814,143, 7,225,880, and 7,278,492, the actuator tool may include a series of pistons which move axially to move a tool mandrel with respect to an outer housing of the tool. The pistons are arranged hydraulically ma series, so that a significant axial force required for tubular expansion is obtained with conventional fluid pressure within the workstring and within the tool. By proper sizing, an actuator from 20 to 30 feet in length is able to generate high expansion forces over a stroke length of from 2 to 5 feet. If an additional length of tubular is to be expanded, the tool may be recocked and restroked a second or multiple times.

The disadvantages of the prior art are overcome by the present invention, in an improved actuator and a method of assembling the actuator as hereinafter disclosed. In one embodiment, a hydraulically powered downhole tool axially moves an expander in a well to radially expand a downhole tubular. A tool mandrel is axially secured to the expander, and a plurality of pistons are movable relative to the tool mandrel and are mechanically interconnected by an outer sleeve or housing of the tool radially exterior of the tool mandrel.

One or more slips supported by the outer sleeve engage the interior wall of the well to temporarily fix an axial position of the outer sleeve in the well. Both the tool mandrel and the outer sleeve include a plurality of sections each having a lower end for interconnection with an upper end of another section. A retainer is provided for supporting each of the outer sleeve sections axially above a respective lower outer sleeve section, thereby exposing mandrel sections for assembly.

According to one embodiment of a method of the invention, the tool is assembled by supporting each of the outer sleeve sections axially above a respective lower sleeve section, thereafter assembling the exposed mandrel section, thereafter axially lowering the outer sleeve section over the mandrel, and thereafter assembling the outer sleeve section and respective lower sleeve section.

According to one aspect of the present invention, there is provided a hydraulically powered downhole tool for axially moving an expander in a well to radially expand a downhole tubular, comprising: a tool mandrel axially secured to the expander, the tool mandrel including a plurality of mandrel sections each having a lower end for interconnection with an upper end of another tool mandrel section; a plurality of pistons each axially movable relative to the tool mandrel and mechanically interconnected by an outer sleeve exterior of the tool mandrel; one or more slips supported by the outer sleeve to temporarily fix an axial position of the outer sleeve in the well; the outer sleeve including the plurality of outer sleeve sections each having a lower end for interconnection to an upper end of another outer sleeve section; and a retainer for supporting an upper outer sleeve section axially above a lower outer sleeve section, thereby exposing upper and lower mandrel sections for assembly, the upper outer sleeve section being axially lowered over the assembled upper and lower mandrel sections for connection with the lower outer sleeve section.

Preferably, hydraulic fluid is supplied to the plurality of pistons through a workstring having an interior in fluid communication with an interior bore in the tool mandrel.

Advantageously, the one or more slips include a plurality of circumferentially spaced slips for engaging an inner wall of the downhole tubular in the well.

Conveniently, the tool further comprises: another plurality of pistons each axially movable relative to the outer sleeve and mechanically interconnected to the tool mandrel.

Preferably, the retainer comprises threads secured to the mandrel; and through ports in the mandrel supply fluid pressure to the plurality of pistons.

Advantageously, each of the one or more slips and the outer sleeve include cam portions to force the slips radially outward in response to axial movement of the tool mandrel relative to the outer sleeve.

According to another aspect of the present invention, there is provided a hydraulically powered downhole tool comprising: a tool mandrel having an interior bore; a plurality of pistons each axially movable relative to the tool mandrel and mechanically interconnected by an outer sleeve exterior of the tool mandrel; another plurality of pistons each axially movable relative to the outer sleeve and mechanically interconnected to the tool mandrel; a work string supplying hydraulic fluid to the plurality of pistons and the another plurality of pistons through an interior of the work string in fluid communication with the interior bore in the tool is mandrel; the tool mandrei incJuding a piurality of mandrel sections each having a lower end for interconnection with an upper end of another tool mandrel section; the outer sleeve including the plurality of outer sleeve sections each having a lower end for interconnection to an upper end of another outer sleeve section; and a retainer for supporting an upper outer sleeve section axially above a respective lower outer sleeve section, thereby exposing upper and lower mandrel sections for assembly, the upper outer sleeve section being axially lowered over the assembled upper and lower mandrel sections connection with the respective lower outer sleeve section.

Preferably, the retainer comprises a latch to temporarily secure an axial position of an outer sleeve section with respect to the tool mandrel.

Conveniently, through ports in the mandrel supply fluid pressure to the plurality of pistons.

Advantageously, the tool further comprises: a plurality of circumferentially spaced slips supported by the outer sleeve for engaging the downhole tubular in the well to temporarily fix an axial position of the outer sleeve in the well.

Preferably, the tool mandrel includes upper and lower sections interconnected by a threaded pin and box connection.

Advantageously, the outer sleeve includes upper and lower sections interconnected by a threaded connection.

Conveniently, the tool is assembled with a substantially vertical assembly axis at a well site.

According to another aspect of the present invention, there is provided a method of assembling a hydraulically powered downhole tool at a well site, comprising: providing a tool mandrel having an interior bore; providing a plurality of pistons each axially movable relative to the tool mandrel and mechanically interconnected by an outer sleeve exterior of the tool mandrel; the tool mandrel including a plurality of mandrel sections each having a lower end for interconnection with an upper end of another tool mandrel section; the outer sleeve including a plurality of outer upper sleeve sections each having a lower end for interconnection to an upper end of an outer lower sleeve section; temporarily supporting each of the outer sleeve sections axially above a respective lower outer sleeve section; thereafter interconnecting two mandrel section; thereafter axially lowering the outer sleeve section over the interconnected mandrel section; and thereafter assembling the outer sleeve section and the outer lower sleeve section.

Preferably, the method further comprises supplying hydraulic fluid to the plurality of pistons through a workstring having an interior in fluid communication with the interior bore in the tool mandrel.

Advantageously, the tool mandrel includes upper and lower sections interconnected by a threaded pin and box connection.

Conveniently, threads on an exterior surface of the mandrel temporarily support a respective outer sleeve section.

Preferably, the method further comprises: supporting one or more slips on the outer sleeve to temporarily fix an axial position of the outer sleeve in the well.

So that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view of an upper portion of a hydraulically actuated tool being assembled at the surface of a well; Figure 2 is a cross-sectional view of a lower portion of the actuator tool; Figure 3 illustrates hydraulically actuated slips for the tool; and Figure 4 illustrates a lower portion of the tool with an expander for radially expanding a downhole tubular.

In various applications, expanders are used to radially expand a length of a downhole tubular so that, for example, the tubular is expanded from a run-in internal diameter of 6 7/8 inch to an expanded internal diameter of 8.4 inches. Expansion of a downhole tubular may be desirable for a mono-bore well system, and may also be used to expand shorter lengths of a tubular for a seal patch, or for a liner hanger operation. In some mono-bore applications, a relatively short length of a tubular may be expanded by a hydraulically powered downhole tool, and thereafter a substantially longer length of the tubular is expanded by exerting an upward pull on the drill pipe workstring.

If the tubular being expanded is deep in the well, and particularly if the well has deviations which cause the workstring to engage the side of the well during an axial pulling operation, tubular expansion by pulling on the workstring may not be feasible. In other applications, the drilling rig or the workstring itself is not able to withstand the high pulling force that must be exerted on the expander to cause the desired tubular expansion.

According to the present invention, an improved actuator is provided for axially moving an expander a substantial axial distance of greater than about 1 meter during stroking of the hydraulic actuator. If the longer expansion of the tubular is required, the tool may be actuated, the tool moved and reset, and the actuator tool again stroked so that a combined length of expanded tubular may be more than 6 meters. Any desired longer length of tubular may be expanded by repeated stroking operations.

Referring now to Figure 1, an upper portion of an expander tool is shown for suspending in a well, which typically includes an existing casing (not shown in Figure 1). The actuator tool 10 may be suspended in the well from a drill pipe or other workstring 14, which is shown threadably connected to top sub 16. A threaded connector 18 is shown not yet threaded to the sub 16, and is shown connected to the tool mandrel 20, which has a central bore fluid passageway 22 therein. Sub 16 and connector 18 are shown threadably disengaged in Figure 1, although the functionally similar components 32 and 34 are shown connected in Figure 2. The tool 10 as shown in Figure 1 also includes an outer sleeve or housing 24 which includes threads 25 as shown in Figure 1 for threadably connecting to outer piston 26.

Hydraulic pressure in the workstring and thus in the passageway 22 may pass through gap in mandrel 20, thereby axially moving the sub 16 and tool mandrel 20 relative to the outer sleeve 24 and the outer piston 26.

An intermediate portion of the tool as shown in Figure 2 illustrates the lower end of mandrel threaded to male connector 32, which is threadably connected to the female connector 34. The hydraulic portion of the tool 10 may have a total length of 100 meters or more. The tool may be sequentially assembled at the well site by interconnecting a lower end of an inner mandrel assembly with a partially assembled inner mandrel. Threads on the inner mandrel sections may be engaged with a tong or other conventional equipment, thereby making up, for example, the connection between 32 and 34. During this assembly operation, is the outer sleeve section 24 may be raised above the location for the inner mandrel connection, and may be retained in that upward position by a suitable clasp or latch 28, as shown in Figure 1. With the outer sleeve raised so as not to interfere with makeup of the inner mandrel connection, the inner mandrel may be made up, and the latch 28 then disengaged and the outer sleeve section lowered so that threads 36 on the lower end of the outer sleeve section as shown in Figure 2 come into mating engagement with the threads 38 on the OD of the outer piston 26. Simultaneously with the makeup of threads at the lower end of the outer sleeve section, the upper end of a sleeve section threaded at 37 mates with threads 29 at the lower end of outer piston 26, as shown in the lower portion of Figure 2.

In Figure 1, the tool mandrel 20 is shown disassembled, and the associated outer sleeve or housing is raised for assembly of the mandrel 20, which is shown in the upper portion of Figure 2. In Figure 2, the lower mandrel connection is made up, and the associated outer sleeve has been lowered over this connection and is also made up. The latch 28 is removed in Figure 2, although a threaded lock for receiving a latch bolt is shown. The outer piston 26 is then securely engaged with the section of the outer sleeve 24 and is in sealing engagement with the inner mandrel 20 due to seals 42. Similarly, the female connector 34 includes inner threads 44 to interconnect a top section of the inner mandrel with connector 34, which has one or more outer seals 46 for sealing engagement with the interior of the outer sleeve section 24 when it is lowered in place. The female connector 34 thus effectively forms an inner piston which is secured to the tool mandrel and sealed to the outer sleeve, while the outer piston 26 inversely is connected to the outer sleeve and is sealed to the inner tool mandrel. Those skilled in the art shall appreciate that a plurality of such pistons and piston assemblies may be provided in various tool sections which are assembled sequentially at the well site. Threads 29 or other members may be used instead of latch 28 to retain the outer sleeve temporarily in a raised position for exposure of the components of an inner mandrel connection, so that after the inner mandrel connection is made during an assembly operation, the outer sleeve may be lowered and the outer sleeve sections then connected.

The running tool mandrel, the outer sleeve, and the pistons thus define variable size hydraulic cavities. A series of mandrel sections, outer sleeve sections, and inner and outer pistons may be provided in the hydraulic sections of the tool, so that axial forces effective stack to create a desired high expansion force. It is a particular feature of the invention that the tool as disclosed herein may generate a hydraulically generated axial force in excess of 1 million pounds, and preferably in excess of 1.5 million pounds, over a relatively long length of approximately 7 meters.

Figure 3 depicts a slip portion of the tool for fixing the axial position of the outer sleeve 24 in place during a tubular expansion operation. The outer sleeve 24 as shown in Figure 1 is thus structurally interconnected, e.g., threads 51, with the slip housing 52 shown in Figure 3, which includes one or more cone sections 54 for mating with similarly tapered cone sections on slips 56 with exterior teeth 57. Axial movement of the inner mandrel 20 relative to the housing 52 interconnected with the outer sleeve 24 thus forces the slips 56 radially outward and into biting engagement with the liner or other tubular 12.

Slips 56 are prevented from moving downward due to engagement with sleeve 74. Collet mechanism 76 is provided between the OD of mandrel 20 and the ID of sleeve 74. Sleeve 74 thus includes suitable windows each for receiving a respective slip. Collet mechanism 76 may include upper and lower heads, and prevents the slips and sleeve 74 from moving downward with the outer sleeve 24 and slip housing 52 during the slip setting operation. The collets 76 are positioned about the mandrel 20 and releasably engage a groove or stop on the mandrel to hold the slips 54 in an upward position, so that the slips do not move downward while being set. The collets 76 may open radially outward after the slips are set, and allow the tool to be reset when the setting assembly is raised. The action of the collet mechanism is thus repeatable, thereby allowing the tool to be repeatedly stroked, recocked, and then restroked.

Keys 53 are provided in the slip housing 52 and cooperate axially between slips 56 and sleeve 74 to allow for rotation of sleeve 74 relative to slip housing 52. Keys 80 are also provided at the lower end of sleeve 74, and slide within axially extending slots or grooves 72 in the inner mandrel 20 to ensure rotation of the sleeve 74 relative to the mandrel 20. Thus, rotation applied to outer sleeve 24 is transmitted to mandrel 20. The slips may be set by dropping a ball on a seat 188 to raise the internal pressure within the mandrel 20 until the increased pressure forces the pistons axially apart, thereby generating a high axial force to set the slips and move the expander. Once the slips are set, the mandrel 20 may be moved upward relative to the slips during the tubing expansion operation.

Figure 4 depicts a tubular 12 which will be radially expanded by the hydraulic actuator moving the expander 48 upward, thereby radially expanding the tubular 12.

A safety joint (not shown) with left-hand threads may allow for latching of the tool with the downhole expander at the lower end of the tool. Left-hand threads allow right-hand rotation of the workstring for drilling operations and, if necessary, left hand rotation to disengage the tool from the downhole expander. The upper half of the safety joint 173 is threaded to inner mandrel 72 and the safety joint lower half threaded at 172 to mandrel 170.

The lower end of tube 204, when positioned as shown in Figure 4, is configured to rotate the lower end of the tool, thereby reliably rotating the bit. During a drilling operation, the lower end of the flow tube 204 which passes through the interior of the expander 48 may be sealed to the lower housing 224, thereby providing a substantially sealed flow path to the bit.

Figure 4 illustrates one embodiment of a lower portion of an expansion tool according to the present invention which is adapted for a liner or other tubular drilling operation. The lower portion of the tool is shown in Figure 4 may have an upper portion which is substantially as described above. The tubular or liner 12 with the expander 48 supported adjacent a lowermost end of the liner, the mandrel 200, and the housings 222 and 224, with a bit or reamer 221 at the end thereof, may first be lowered in a well, then the remainder of the tool lowered so that keyed collet heads 194 on the lowered tool connect with the threads 198 on the mandrel 200. The liner 12, once expanded, may have its upper end within a casing or other downhole tubular or uncased wellbore (not shown in Figure 4).

Sleeve 174 threaded to mandrel 170 has lower clutch teeth 176 circumferentially arranged thereon. The clutch teeth 176 mate with and thus engage clutch teeth 177 at the upper end of mandrel 200. A radially external surface of the mandrel 200 includes axially extending splines 182, which mate with similar splines 180 on the modified liner section 178. The splines 180 on the liner section 178 similarly extend axially, and the upper and lower ends of the splines may include conventional tapers so that the mandrel 200 effectively slides along the splines while torque is transferred from the mandrel 170 to the mandrel 200, and from the mandrel 200 to the liner 12 to be subsequently expanded, thereby allowing the unexpanded liner and the tool to be rotated together as an assembly. High torque in the drill pipe workstring 14 and thus in the mandrel 20 may be transmitted radially outward from the inner mandrel to the tubular 12. The mandrel 170 includes a central bore 186, and a selectively sized seat 188 for subsequently receiving a ball or other plug member.

Mandrel 170 in turn is threaded at 192 to mandrel 190. When the tool is latched into the liner as shown in Figure 4, the upper end of mandrel 200 circumferentially surrounds and is axially slidable relative to the lower end of the mandrel 170, so that upper end of mandrel 200 is positioned circumferentially about the lower end of mandrel 170. Collet fingers 196 with lower heads 194 are threaded at 198 to the mandrel 200 when the tool is assembled downhole, as discussed above, and may slide axially relative to mandrel 170 to allow the clutch teeth to be disengaged when the work string 12 is subsequently picked up. Flow through passages 202 extend from the inside of the liner section 212 to the exterior of mandrel 190 to allow for drainage and prevent an undesirable pressure head in the tool.

Tube 204 may thus be threaded to and sealed to mandrel 190, and accordingly moves axially with mandrel 190. Expanding members 48 are supported adjacent the lower end of liner section 178, and may be threaded to the liner section as disclosed in U.S. Application Serial No. 1 1/803,389, hereby incorporated by reference. Lower housing 222 sandwiches the expander 48 between lower inwardly formed section 228 of the liner 212 and housing 222. For the embodiment depicted in Figure 4, sleeve 230 may be externally threaded to internal threads on section 228 of the liner. Sleeve 230 is prevented from moving upward by engagement with shoulder 232 on mandrel 200, thereby rotating mandrel 200 with the lower housing 222. Sleeve 230 thus acts as a positive stop to prevent upward movement of the expander 48 and the liner 212 prior to activation of the hydraulic power section of the tool.

As shown in Figure 4, the section 228 of the liner is radially inwardly formed to reduce the thickness of the sleeve 230 without increasing the thickness of the liner.

Housing 222 is threaded to the lower end of mandrel 200, and to the upper end of bit housing 224. Lower threads 220 on housing 224 are provided for conventionally receiving a bit or reamer 222 for drilling the hole in response to liner rotation. Tube 204 thus includes a central bore about axis 218 which supplies fluid to the bit 222. Tube 204 remains sealed to the housing 224 during axial movement of the tube.

To conduct a tubular drilling or reaming operation, the tool as shown in Figure 4 may be positioned within the liner 12 after the liner is run at least partially in the hole, then the liner and the tool lowered to a drilling depth. When the tool is subsequently picked up, fluid from within the interior of the tool may drain out through the ports 202 in housing 222, so that the entire column of fluid does not have to be lifted to the surface with the tool. A seal 223 between tube 204 and the housing 224 ensures the supply of a high pressure fluid to the bit 222 when the tool is positioned as shown in Figure 4.

The mandrel 200 which surrounds the lower end of mandrel 170 may be threaded at 216 to housing 222. Mandrel 190 is rotated with the mandrel 170, thereby also rotating tube 204.

Torque may be transmitted from the mandrel 200 to the bit or reamer 222 without torque having to be transmitted through the expander 48.

After the liner 212 or other tubular drilling operation is complete, the drill pipe 12 may be picked up, thereby lifting the mandrel 170 and disengaging the clutch 175. Thereafter, the tool may be actuated, as explained above, so that the expander 48 is forced upward while the liner 12 remains held in place by slips 56, thereby expanding a length of the liner during an actuator stroking operation. As previously discussed, the slip resetting and stroking operation may be repeated until a desired length of the liner is expanded, after which time the liner is fixed at its lower end in the well, and an upward force on a drill pipe may be used to expand upper sections of the liner without stroking the tool.

The tool as disclosed herein may be recocked during an upward stroking operation, then the hydraulic section activated to set the slips and to pull up on the expander and expand a length of the tubular. The tool may be used to expand a tubular in an open hole operation, and may also be used to press a tubular tightly against the wall of another tubular in a cladding operation. Moreover, the technique is able to reliably expand overlapping joints of pipe sections which are expanded, thereby providing a monodiameter or continuous ID bore application.

The above application discloses elongate components, such as a tool mandrel and an outer sleeve exterior of the tool mandrel, which in practice are each a series of interconnected components, so the tool mandrel and the outer sleeve are each an assembly of a plurality of interconnected tool mandrel sections and a plurality of outer sleeve sections. Accordingly, each of these terms as used herein should be understood to include a plurality of sections which together form the elongate components.

Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow, io Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or integers.

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention. e

Claims

CLAIMS: 1. A hydraulically powered downhole tool for axially moving an expander in a well to radially expand a downhole tubular, comprising: a tool mandrel axially secured to the expander, the too! mandrel including a plurality of mandrel sections each having a lower end for interconnection with an upper end of another tool mandrel section; a plurality of pistons each axially movable relative to the tool mandrel and mechanically interconnected by an outer sleeve exterior of the tool mandrel; one or more slips supported by the outer sleeve to temporarily fix an axial position of the outer sleeve in the well; the outer sleeve including the plurality of outer sleeve sections each having a lower end for interconnection to an upper end of another outer sleeve section; and a retainer for supporting an upper outer sleeve section axially above a lower outer sleeve section, thereby exposing upper and lower mandrel sections for assembly, the upper outer sleeve section being axially lowered over the assembled upper and lower mandrel sections for connection with the lower outer sleeve section.
2. A downhole tool as defined in Claim 1, wherein hydraulic fluid is supplied to the plurality of pistons through a workstring having an interior in fluid communication with an interior bore in the tool mandrel.
3. A downhole tool as defined in Claim 1 or Claim 2, wherein the one or more slips include a plurality of circumferentially spaced slips for engaging an inner wall of the downhole tubular in the well.
4. A downhole tool as defined in any preceding claim, further comprising: another plurality of pistons each axially movable relative to the outer sleeve and mechanically interconnected to the tool mandrel.
5. A downhole tool as defined in any preceding claim, wherein the retainer comprises threads secured to the mandrel; and through ports in the mandrel supply fluid pressure to the plurality of pistons.
6. A downhole tool as defined in any preceding claim, wherein each of the one or more slips and the outer sleeve include cam portions to force the slips radially outward in response to axial movement of the tool mandrel relative to the outer sleeve.
7. A hydraulically powered downhole tool comprising: a tool mandrel having an interior bore; a plurality of pistons each axially movable relative to the tool mandrel and mechanically interconnected by an outer sleeve exterior of the tool mandrel; another plurality of pistons each axially movable relative to the outer sleeve and mechanically interconnected to the tool mandrel; a work string supplying hydraulic fluid to the plurality of pistons and the another plurality of pistons through an interior of the work string in fluid communication with the interior bore in the tool mandrel; the tool mandrel including a plurality of mandrel sections each having a lower end for interconnection with an upper end of another tool mandrel section; the outer sleeve including the plurality of outer sleeve sections each having a lower end for interconnection to an upper end of another outer sleeve section; and a retainer for supporting an upper outer sleeve section axially above a respective lower outer sleeve section, thereby exposing upper and lower mandrel sections for assembly, the upper outer sleeve section being axially lowered over the assembled upper and lower mandrel sections connection with the respective lower outer sleeve section.
8. A downhole tool as defined in Claim 7, wherein the retainer comprises a latch to temporarily secure an axial position of an outer sleeve section with respect to the tool mandrel.
9. A downhole tool as defined in Claim 7 or Claim 8, wherein through ports in the mandrel supply fluid pressure to the plurality of pistons.
10. A downhole tool as defined in any one of claims 7 to 9, further comprising: a plurality of circumferentially spaced slips supported by the outer sleeve for engaging the downhole tubular in the well to temporarily fix an axial position of the outer sleeve in the well.
11. A dowrihole tool as defined in any preceding claim, wherein the tool mandrel includes upper and lower sections interconnected by a threaded pin and box connection.
12. A downhole tool as defined in any preceding claim, wherein the outer sleeve includes upper and lower sections interconnected by a threaded connection.
13. A downhole tool as defined in any preceding claims, wherein the tool is assembled with a substantially vertical assembly axis at a well site.
14. A method of assembling a hydraulically powered downhole tool at a well site, comprising: providing a tool mandrel having an interior bore; providing a plurality of pistons each axially movable relative to the tool mandrel and mechanically interconnected by an outer sleeve exterior of the tool mandrel; the tool mandrel including a plurality of mandrel sections each having a lower end for interconnection with an upper end of another tool mandrel section; the outer sleeve including a plurality of outer upper sleeve sections each having a lower end for interconnection to an upper end of an outer lower sleeve section; temporarily supporting each of the outer sleeve sections axially above a respective lower outer sleeve section; thereafter interconnecting two mandrel section; thereafter axially lowering the outer sleeve section over the interconnected mandrel section; and thereafter assembling the outer sleeve section and the outer lower sleeve section.
15. A method as defined in Claim 14, further comprising: supplying hydraulic fluid to the plurality of pistons through a workstring having an interior in fluid communication with the interior bore in the tool mandrel.
16. A method as defined in Claim 14 or Claim 15, wherein the tool mandrel includes upper and lower sections interconnected by a threaded pin and box connection.
17. A method as defined in any one of claims 14 to 16, wherein threads on an exterior surface of the mandrel temporarily supports a respective outer sleeve section.
18. A method as defined in any one of claims 14 to 17, further comprising: supporting one or more slips on the outer sleeve to temporarily fix an axial position of the outer sleeve in the well.
19. A hydraulically powered downhole tool substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
20. A method of assembling a hydraulically powered downhole tool at a well site substantially as hereinbefore described with reference to the accompanying drawings.