Wells – Packers or plugs – With expanding anchor
Reexamination Certificate
1999-07-28
2001-07-10
Bagnell, David (Department: 3672)
Wells
Packers or plugs
With expanding anchor
C166S123000
Reexamination Certificate
active
06257331
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a downhole assembly used in the positioning and setting of well tools within a wellbore and in one aspect relates to a downhole assembly for positioning and setting a well tool, e.g. packer, within a wellbore wherein the assembly is releasably latched to and is supported by the workstring (e.g. e-line, wire line, coiled tubing, etc.) until the tool has been positioned within the wellbore and is ready to be set.
2. Background
As will be understood in the art, there are instances during the completion and/or production of a well where it may become necessary to lower and set a well tool in the wellbore in order to carry out a particular operation. Such well tools include permanent packers, bridge plugs, etc. and are well known in the art. The well tool is carried on the lower end of a “setting tool” which, in turn, is manipulated to set the well tool once it has been lowered and properly positioned within the wellbore. As will be understood in the art, the setting tool may be actuated in a variety of ways, e.g. motor-driven screw carried by the setting tool, etc., or, as is often the case, it is hydraulically actuated.
A typical setting tool which is hydraulically actuated is one which is comprised of a housing having a “draw rod” extending therethrough. The draw rod is connected at its lower end to the well tool and at its upper end to the lower end of the work string (e.g. wireline, regular or coiled tubing, etc.) which, in turn, is used to lower the setting tool-well tool assembly into the wellbore. Once the assembly is properly positioned within the wellbore, the hydraulic setting tool is actuated by forcing fluid into a chamber within said housing which, in turn, drives the housing downward relative to the draw rod and into contact with the well tool to set slips, etc. on the well tool while at the same time the draw rod is held in position by the workstring. The continued relative movement between the housing and the draw rod will cause shear pins in the tool to fail or the draw rod, itself, to fail at a predetermined, weak point whereby the workstring and the setting tool can then be retrieved to the surface while leaving the set well tool in the wellbore.
While this procedure has proved effective in most applications, the possibly always exists that the well tool may become stuck with the wellbore as it is being lowered into position. With known setting tools, this can create a problem in that the draw rod of the setting is effectively connected directly to and fully supports the well tool. Accordingly, if the tool becomes stuck or it is desired to raise the tool before it is set, any upward force from the workstring is applied directly to the draw rod. If the well tool becomes stuck or wedged within the wellbore, the shear pins in the assembly and/or the draw rod can shear at its weak point, thereby leaving a partially-set, well tool at the wrong position within the wellbore. As will be understood, this can result in considerable downtime and added expense in correcting this problem.
SUMMARY OF THE INVENTION
The present invention provides a downhole assembly for setting a well tool (e.g. packer, plug, etc.) within a wellbore wherein the setting tool of the assembly includes a draw rod which is made in two portions which are slidably connected to allow relative movement therebetween. The draw rod is releasably latched in an unloaded position as the assembly is lowered and positioned within the wellbore so that the well tool of the assembly cannot be set inadvertently and can be retrieved before the well tool is set without risk of shearing the draw rod.
More specifically, the downhole assembly of the present invention is comprised of a setting tool having a draw rod which, in turn, has an upper portion and a lower portion which are slidably connected to allow relative movement therebetween. The upper portion is connected to a workstring (e.g. e-line, wire line, tubing, etc.) and the lower portion is connected to the well tool.
The present assembly includes an adapter section which, in turn, includes latch means for releasably latching the upper portion of the draw rod to the well tool whereby any upward and/or downward force from the workstring is applied to the well tool through the adapter section and not through the draw rod thereby avoiding the inadvertent setting of the well tool as the assembly is raised or lowered in the wellbore. Preferably, the latch means is comprised of a collet which is attached to the upper portion of the draw rod. The collet has a plurality of fingers which are normally biased into contact with a fishing neck on the well tool to releasably latch the upper portion to the well tool.
The fingers are held in their latched position by an internal collar on the lower end of the housing of the setting tool when the housing is in a first position, i.e. as the downhole assembly is run into the wellbore. When the setting tool is actuated, the housing is moved to a second position wherein the collar on the housing moves out of contact with said fingers thereby releasing said fingers from their latched position.
The upper portion of the draw rod is comprised of a mandrel which is slidably mounted in the upper portion of the housing and has a piston thereon which, in effect, cooperates with a shoulder within said housing to form a chamber within said housing. Upon actuation of the setting tool, a non-compressible fluid (e.g. hydraulic fluid) is flowed into the second chamber to move the housing from its first or latched position to its second or unlatched position. The setting tool can be actuated in the same manner as are several other known setting tools of this type
By releasably latching the upper portion of the draw rod to the well tool through the adapter section, the lower portion of the draw rod is “unloaded” and is isolated from the forces in the workstring during the positioning of the downhole assembly. This effectively connects the workstring directly to the well tool so that if the downhole assembly becomes stuck in the wellbore or it has to be raised before it has reached its destination, it can be retrieved by the workstring without inadvertently shearing the draw rod or leaving a stuck well tool in the wellbore.
REFERENCES:
patent: 3186485 (1965-06-01), Owen
patent: 3776307 (1973-12-01), Young
patent: 4773478 (1988-09-01), Streich
Blount Curtis G.
Hearn David D.
Atlantic Richfield Company
Bagnell David
Dawelbeit Kamal
Faulconer Drude
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