Wells – Processes – Placing or shifting well part
Reexamination Certificate
1999-02-18
2001-10-16
Bagnell, David (Department: 3673)
Wells
Processes
Placing or shifting well part
C166S134000, C166S206000
Reexamination Certificate
active
06302217
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to anchoring apparatus utilized in subterranean wells and, in an embodiment described herein, more particularly provides a packer for use in extreme service conditions.
In a typical packer having a single slip, which may consist of a single slip member or multiple circumferentially distributed slip segments, forces applied to the packer are necessarily resisted by the same slip. Thus, when a downwardly directed tubing load and a downwardly directed differential pressure are applied to the packer, the single slip must resist both by its gripping engagement with a tubular structure (such as casing, tubing, other equipment, etc.) in which it is set. In extreme service conditions, the slip may need to be radially outwardly forced into contact with the tubular structure, in order to resist the forces applied to the packer, with enough force to cause damage to the tubular structure, the packer, or both.
If the gripping surface area on the slip is increased in an attempt to increase the gripping engagement between the slip and the tubular structure, it has been found that it is more difficult for the slip to initially bite into the tubular structure. This is due to the fact that more of the slip is required to deform more of the tubular structure. Consequently, more radially outwardly directed force must be applied to the slip, thereby causing damage to the tubular structure.
It would be advantageous to be able to use multiple axially spaced apart slips on an anchoring device, in order to distribute forces applied to the device among the slips. In addition, it would be advantageous for each of the multiple slips to be dual slips, so that each of the slips could resist forces applied thereto in both axial directions. Unfortunately, the use of multiple axially spaced apart slips presents additional problems, particularly when the slips are dual slips.
For example, it may be difficult to retrieve the anchoring device after the slips have been grippingly engaged with the tubular structure. This is due to the fact that slips generally have inclined teeth, serrations, etc. formed thereon which, when axially opposed with other slips, resist disengagement from the tubular structure.
As another example, mechanisms to extend and then retract multiple slips may be prohibitively complex, and therefore unreliable, uneconomical and/or too delicate for use in extreme service conditions. Thus, an extreme service anchoring apparatus utilizing multiple axially spaced apart slips should include appropriately robust, economical and reliable mechanisms for extending the slips and, where the apparatus is to be made retrievable, should include a retracting mechanism with similar qualities.
To further enable convenient retrieval of an anchoring apparatus, debris which accumulates about the apparatus should be minimized. Such accumulation of debris may be eliminated or lessened by providing an appropriately configured debris barrier. However, deployment of the debris barrier should not require complex mechanisms or procedures, and should not interfere with anchoring the apparatus. Additionally, deployment of the debris barrier or barriers may be useful in controlling anchoring of the apparatus.
From the foregoing, it can be seen that it would be quite desirable to provide an anchoring apparatus in which one or more debris barriers may be conveniently deployed. It is accordingly an object of the present invention to provide conveniently deployable debris barriers for an anchoring apparatus. It is another object of the present invention to provide debris barriers which may control or enhance setting of the apparatus. It is a still further object of the present invention to provide methods of producing a slip for an anchoring apparatus, the slip being configured for convenient use with a debris barrier.
SUMMARY OF THE INVENTION
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a packer is provided which uses one or more debris barriers to reduce debris accumulation about the packer. The packer is reliable, retrievable, economical and convenient in operation. Associated methods are also provided.
In one aspect of the present invention, apparatus is provided which includes multiple debris barriers positioned relative to a slip, such that the slip is substantially between the debris barriers when the slip is radially outwardly extended. In one described embodiment, the slip pushes the debris barriers up sloped outer surfaces of wedge members, thereby radially outwardly extending the debris barriers.
In another aspect of the present invention, each debris barrier is disposed in a recess. The slip pushes the debris barriers out of the recesses when the slip is radially outwardly extended. In one described embodiment, the recesses are configured so that one of the debris barriers is pushed out of its recess before another one of the debris barriers. This enables the setting action of the slip to be controlled.
In another aspect of the present invention, radially extendable debris barriers are provided on the apparatus and disposed above and below the upper slip. The debris barriers are positioned on laterally inclined outer side surfaces of wedges associated with the upper slip. When the upper slip is radially outwardly extended by the wedges, axial displacement of the slip relative to the wedges causes the debris barriers to radially outwardly extend as well. At least the upper one of the debris barriers closes off an annular gap between the upper wedge and the tubular structure in which the apparatus is set, thereby excluding debris from accumulating about the apparatus and enhancing retrieval of the apparatus.
In yet another aspect of the present invention, methods of producing a slip are provided. The slip has relatively narrow slots, which enhance the slip's ability to support a debris barrier. In one embodiment, the slots are cut using an abrasive water jet. In another embodiment, the slots are cut with the slip immersed in a liquid.
The exemplary embodiment of the invention described below is in a packer specifically designed for use in extreme service conditions. However, the principles of the present invention may be readily utilized in other equipment, such as plugs, hangers, etc.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.
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Hilts Robert L.
Kilgore Marion D.
Bagnell David
Halliburton Energy Service,s Inc.
Herman Paul I.
Singh Sunil
Smith Marlin R.
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