Wells – Packers or plugs – With expanding anchor
Patent
1993-10-05
1994-11-22
Buiz, Michael Powell
Wells
Packers or plugs
With expanding anchor
166123, E21B 2300
Patent
active
053660102
DESCRIPTION:
BRIEF SUMMARY
This invention relates to tools for downhole use in oil and gas wells and in particular, but not exclusively, to retrievable bridge plugs and running tools therefor. The invention also relates to fishing tools for retrieving such plugs from oil wells.
Bridge plugs are widely used in the oil and gas exploration and extraction industries and are run downhole from the surface for setting in a string of pipe. Bridge plugs may be used to seal a portion of pipe to permit the integrity of the pipe to be checked using pressure testing, to act as a barrier within the pipe to seal the well, or to act as a carrier for downhole monitoring equipment. Conventional bridge plugs, and many other downhole tools, are located in the pipe bore by running a lock provided on the plug into a slot or recess in the pipe string, the locations of such recesses being identified by locating shoulders, commonly known as landing nipples. A string of pipe may have several landing nipples over the length of the pipe, each nipple producing a step down in diameter. This leads to a restriction on the diameter of the lower sections of the pipe reducing the flow area through the pipe. Such landing nipples may also become worn through use and may also be "washed out" by the flow of abrasive fluid past the restriction. Repair of the landing nipples requires pulling and replacement of the pipe string.
Conventional bridge plugs require considerable forces to be used in setting the bridge plug in the pipe, and in particular in providing a seal between the exterior of the plug body and the pipe wall. The magnitude of the necessary setting forces is such that conventional wirelines and slick lines are not capable of providing the necessary force such that explosive charges must be provided in the bridge plug, the charges acting on hydraulic fluid to provide the necessary locking and sealing forces. Detonation of the charge is achieved through use of an electric line extending from the surface. While the locking arrangement achieved through use of such explosive charges is generally satisfactory, the use of such charges requires the presence of specially skilled and licensed operators and normally require the imposition of "radio silence" during the setting operation to minimise the risk of the charge being accidentally set off. For many operations, particularly offshore, the requirement for such radio silence may effectively bring all other work on the rig which involves sending of signals to a halt.
It is among the objects of the present invention to provide tools which obviate and mitigate these disadvantages. In particular, it is an object of one aspect of the the present invention to provide a downhole tool which may be set in sealing engagement with a bore or pipe wall using only a wireline or slick line connection to the surface. It is a further object of another aspect of the present invention to provide a downhole tool which may be set at any desired depth in a pipe or bore without relying on a shoulder or landing nipple on the well.
One aspect of the present invention provides a tool a tool for downhole use in oil and gas wells comprising: a body having first and second locking means moveable between a retracted configuration to permit movement of the tool through a bore and a radially extended configuration for locking engagement with a bore wall, the first locking means being mounted on a locking assembly via biasing means; a resilient ring member between the locking means and compressible into sealing engagement with a bore wall by relative axial movement of the locking means towards each other and at least the first locking means being moveable axially on the body to provide compression of the ring member; and cam means between the ring member and the first locking means for extending the first locking means from the retracted configuration into the extended configuration, the setting force to compress the ring member into engagement with the bore wall being applied via the locking assembly and the cam means, the proportion of said settin
REFERENCES:
patent: 4432418 (1984-02-01), Mayland
patent: 4688634 (1987-08-01), Lustig et al.
patent: 4832129 (1989-05-01), Sproul et al.
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