The present invention relates to downhole tools for anchoring a portion of the tool in a well. More particularly, the present invention relates to a downhole tool such as a liner hanger assembly for hanging a liner in a well, and to an improved slip releasing mechanism within the downhole tool.
Various types of downhole tools employ slips which expand radially outward to engage the interior of a downhole tubular, thereby securing the tool in the well. Various types of slip mechanisms have been used for this purpose, with slips conventionally having outer teeth which bite into the inner surface of the downhole tubular to secure the tool in the well.
One of the significant problems with downhole tools having slip mechanisms is that the slip mechanism may be inadvertently actuated before actuation is intended, in which case the slip or slips may radially expand and engage the tubular. It may then be difficult or practically impossible in some instances to break the connection between the downhole tool and the tubular, and accordingly the tool cannot be easily retrieved to the surface, repaired, and then again reinserted into the well. In other instances, the slip may be expanded when the tool is at a desired downhole position, but the running tool/set tool connection cannot be reliably released, so that the retrievable portion of the tool cannot be returned to the surface.
U.S. Pat. Nos. 3,920,057 and 4,281,711 disclose a liner hanger assembly for hanging a liner in a well. A liner hanger assembly is also disclosed in U.S. Pat. No. 6,739,398. The '398 patent discloses a tool that relies upon shear pins to keep the slips from prematurely releasing while the tool is run in the hole. While pushing on the running tool may not release the slip accidentally, if debris were to build up around the tieback or other components of the liner hanger and the operator then pushed or pulled on the tool, the shear pins may shear and thereby release the slip. Tools that allow axial forces to be transmitted to the tool through the running string to shear pins and release the slip may thus inadvertently be actuated when running the tool to the desired depth in the well.
U.S. Pat. Nos. 4,712,614, 4,603,743, 4,311,194 and 4,287,949 also rely on shear pins to keep from releasing the slips. U.S. Pat. No. 5,318,131 is another example of the downhole tool using shear pins to prevent release of slips. Downhole tools with shear pins to keep the slip in the retracted position while running the tool in the hole generally have exposed hydraulic actuation ports. If debris builds up around the tool while tripping into the hole, the dragging action could shear the pins, in which case the slip will set and thereby prevent the tool from being positioned at its desired location in the well. Increased hydraulic pressure may also cause the pins to prematurely shear.
The disadvantages of the prior art are overcome by the present invention, and a liner hanger with an improved slip releasing mechanism is hereinafter disclosed.
According to one embodiment, a running tool for releasing a slip and preventing premature activation of the slip includes a tool mandrel supported on a running string, and a blocking member for closing off a port in the mandrel when the tool is run in the well and for selectively opening the port to set the slip. A locking member prevents premature setting of the slip, with the locking member being axially securable to the mandrel when the running tool is run in the well. An actuating piston is moveable with respect to the tool mandrel when the port is open to move the locking member and release the slip to set in the well.
The running tool may lock the slip in a reduced diameter position when running the tool into the wellbore and selectively releases the slip to move radially outward to a set position for suspending a downhole tool in a tubular. The running tool includes a mandrel having a through passage, and a locking device supported on the mandrel for retaining the slip in the reduced diameter position when running the tool into the well. A hydraulic port in the mandrel is closed to mandrel internal pressure as the downhole tool is run into the wellbore, and is selectively open when desired. A piston is moveable in response to mandrel internal pressure applied through the hydraulic port to unlock the locking device. Further movement of the piston may release the slip from the reduced diameter position to the set position. Still further movement of the piston may disengage the running tool from the downhole tool, so that the running tool may be retrieved to the surface while the downhole tool is set in the well.
These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.
To hang off a liner, the running tool 100 is initially attached to the lower end of a work string and releasably connected to the liner hanger, from which the liner is suspended for lowering into the bore hole within the previously set casing or liner C.
A tieback receptacle 102 as shown in
By incorporating an axially movable slick joint 132 (which may functionally be an extension of the mandrel 104), the running tool may be axially moved without breaking the seal provided by the cementing bushing 130 (see
The slip release subassembly 210 as shown in
Piston sleeve 216 is disposed about and is axially moveable relative to mandrel 104. An upper sealing ring 162 is disposed about a smaller O.D. of the running tool mandrel than is the lower sealing ring 164 to form an annular pressure chamber between them for lifting the tieback receptacle 102 from the position shown in
The slip 120 shown in
Ratchet ring 136 is also shown in
The packer element 122 may be set by using spring-biased pusher C-ring 180 (see
The first time the packer setting assembly is moved out of the polished bore receptacle, a trip ring may snap to a radially outward position. When the packer setting assembly is subsequently reinserted into the polished bore receptacle, the trip ring will engage the top of the polished bore receptacle, and the packer setting C-ring is positioned within the polished bore receptacle. When set down force is applied, the trip ring will move radially inward due to camming action. The entire packer setting assembly may thus be lowered to bottom out on a lower portion of the running adapter prior to initiating the cementing operation. The next time the packer setting assembly is raised out of the polished bore receptacle, the radially outward biasing force of the C-ring will cause the C-ring to engage the top of the tieback. Further details regarding the packer seating assembly are disclosed in U.S. Pat. No. 6,739,398, hereby incorporated by reference.
The packer element 122 may be of a construction as described in U.S. Pat. No. 6,666,276, hereby incorporated by reference, comprising an inner metal body for sliding over the cone and annular flanges or ribs which extend outwardly from the body to engage the casing. Rings of resilient sealing material may be mounted between such ribs. The seal bodies may be formed of a material having substantial elasticity to span the annulus between the liner hanger and the casing C.
The packer setting assembly thus allows the C-ring to be locked in a collapsed position by a locking mechanism to prevent the C-ring from moving to its expanded position. As discussed above, this allows the packer setting assembly to be pulled out of the tie back receptacle one time without releasing the C-ring, and allows the lockout mechanism to engage the top of the tie back receptacle for weight set down. The next time the packer assembly is pulled out of the tie back receptacle, the C-ring is allowed to expand radially outward for engagement with the top of the tie back receptacle.
The C-ring seat subassembly 170 as shown in
After activating the lower C-ring seat subassembly 170 (see
The slip or slips are kept from prematurely setting as the running tool and slip are run into the wellbore by a locking member.
The ball seat 116 and sleeve 112 move axially down after a ball lands on the seat 116, thereby exposing hydraulic ports 166 to the slip releasing piston 216. The slip releasing piston 216 thus is moved up in response to pressure within the mandrel, letting the collar 220 and collet heads unlock and move up to allow the slip to move up and release from the mandrel. Once the collet heads 215 enter the groove 228 in the slip releasing piston 216 (see
The locking collar 220 thus keeps the tieback 102 from moving up and prematurely releasing the slip 126. The tieback 102 may be threaded to a pusher sleeve which is attached to the cone 128, which in turn is attached to the tie bars 117 which pull on and release the slip from the pocket 119, so that the slip may thereafter move radially outward and set. As the slip releasing piston 216 moves up after engaging collar 220, it pushes the tieback pickup ring 212 up, since C-ring 212 is supported on a lower end of tieback pickup ring adjustment nut 224, which is threaded at 225 to the collar 220. As the slip releasing piston 216 moves up with the C-ring 212, the pickup ring moves into a groove 230 in the releasing sleeve 226, releasing from the tieback 102, thus releasing the retrievable portion of the tool from the anchored portion of the tool. During movement of the piston 216, the tieback pickup ring releasing sleeve 226 remains stationary with the mandrel 104. The tieback pickup ring 212, which acts as a releasing device, in turn pushes up the tieback 102 to release the slip. Once the locking collar 220 is disengaged, the tieback 102 may move axially to release the slip. For these applications, the slip or slips, once released, may be set by applying a substantial weight to the tool to set the slip.
A releasing ring adjustment nut 231 (see
Those skilled in the art will appreciate that the running tool incorporates a locking device to keep the slip from releasing and prematurely setting while tripping into the wellbore. Fluid pressure within the drill string, rotation of the drill string, or axial forces exerted on the drill string will not inadvertently release the slip. The locking collar 220 and C-ring 212 keep the slip 126 locked in its run in position. Only after the ball is dropped and lands on the ball seat so that the hydraulic port 166 is opened can fluid pressure be applied to push the slip releasing piston up. As the piston moves up, it unlocks a locking collar 220. Further upward movement of the piston 216 releases the slip 126 and still further movement disengages the tieback pickup ring 212, which unlocks the retrievable running portion of the tool from the slip release piston and related components.
Travel of the piston 216 will push up on the tieback pickup ring 212, which picks up the tieback, which in turn picks up the tie bars which pick up the slip 126 to release the slip. Continued upward movement of a slip releasing piston will unlock the pickup ring 212 from the tieback 102, thereby unlocking the tieback from the running tool. The slip is thereby released and set, and the slip releasing assembly is disengaged from the liner hanger.
If the slips are circumferentially spaced, the reaction of the slip moving up the cone creates hoop loading to cause lower and more uniform stress in the casing and liner hanger. The loads are transferred circumferentially, rather than radially inwardly, thereby preventing hanger collapse and burst of the casing. The upper end of each slip may be connected to the lower end of a tie bar which extends slidably through the downwardly and inwardly tapered cone for the slip.
In an alternative slip assembly, the slip assembly may include a ring disposed about the slip cone in which there is a recess beneath the cone taper. The recess receives and retains the lower end of the slip when in its contracted position. However, as the slip is pulled upwardly by raising of the tie bar or slat, the lower end of the slip is pulled out of the recess and the slip is permitted to expand outwardly against the casing.
If the slip is a C-shaped slip, it has the ability to contract and expand between a contracted run-in position, and its extended or maximum expansion position. This maximum expansion position preferably is the as-fabricated or as-machined position for the slip. Thus, the slip may be designed so as to approach this expanded position as the slips expand outwardly into engagement with the casing.
Those skilled in the art will appreciate that the slip releasing mechanism as disclosed herein may release a single slip which is set to anchor the tool in the downhole tubular, or may release a plurality of axially spaced and/or circumferentially spaced slips to similarly set the tool in the downhole tubular. Also, the releasing mechanism could be employed to release other components of the downhole tool which are moved radially outward to engage the downhole tubular, such as a packer, although premature setting of a downhole tool slip is a more significant problem than premature setting of a packer, since a prematurely set packer may not prevent axial movement of the downhole tool.
The techniques of the present invention are particularly well suited for preventing the premature release of slips and the desired reliable setting of slips for a downhole liner hanger, but may also be used to prevent premature setting or releasing of downhole packers, downhole valves, multilateral tools, and other downhole tools.
As disclosed herein, the hydraulic ports are opened in response to a ball landing on a seat, which then shifts the ball seat downward to expose the ports. Various types of closure devices other than balls may be used for this purpose, including plugs. If used, the ball may be either deformable or the seat may be radially expanded to allow the ball to ultimately pass through the seat. Hydraulic pressure above the closed seat may be used to move the releasing piston upward, but in other embodiments the downhole tool components could be arranged so that the high pressure above the closed seat passes through the hydraulic port to push the piston downward, which then causes the release of the lock. In still other embodiments, a pair of axially spaced plugs or valves may be positioned along the bore of the mandrel, and pressurized gas released within the bore to pass through the hydraulic port and actuate the piston.
In a preferred embodiment, the same piston is used to move axially to unlock the locking member, and continues to move axially to move the releasing ring and the tieback axially, and finally releases the releasing ring from the tieback when the slip is set. In other embodiments, more than one piston could be used for achieving these purposes. It should be understood that the increase in pressure above the seated ball may accomplish each of these tasks in a successive and fairly short timeframe. Alternatively, pressure levels could be increased above the seated ball so that, for example, a first pressure is used to unlock the locking member, and a second higher pressure is then used to move the releasing ring and tieback upward, then if desired, a still higher pressure used to mechanically separate the tieback from the retrievable portion of the tool.
As disclosed herein, a collet mechanism is used to lock and subsequently release of the slips once the piston has moved axially upward in the disclosed embodiment. In other embodiments, the function served by the collet mechanism to unlock the slips could be accomplished with a C-ring, which similarly fits within a groove to lock the locking collar to the mandrel until the groove in the piston is aligned with the C-ring to release the collar from the mandrel. Also, a C-ring preferably is used to release the tieback from the portion of the running tool to be retrieved, although a collet mechanism could be used rather than a C-ring for this purpose.
While preferred embodiments of the present invention have been illustrated in detail, it is apparent that modification and adaptations of the preferred embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention as set forth in the following claims.
This application claims the priority of U.S. Provisional Application No. 60/859,140 filed on Nov. 15, 2006, the disclosure of which is incorporated herein by reference for all purposes.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2007/023792 | 11/15/2007 | WO | 00 | 5/8/2009 |
Publishing Document | Publishing Date | Country | Kind |
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WO2008/076189 | 6/26/2008 | WO | A |
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2328840 | O'Leary | Sep 1943 | A |
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6739398 | Yokley et al. | May 2004 | B1 |
Number | Date | Country | |
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20100038096 A1 | Feb 2010 | US |
Number | Date | Country | |
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60859140 | Nov 2006 | US |