Wells – Processes – Freeing stuck object – grappling or fishing in well
Reexamination Certificate
1998-08-25
2001-07-31
Suchfield, George (Department: 3672)
Wells
Processes
Freeing stuck object, grappling or fishing in well
C166S098000, C166S237000, C166S387000, C294S086250
Reexamination Certificate
active
06267180
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to a system for use in a subterranean wellbore, and more specifically to a packer releasing tool and system for releasing a packer from a wellbore.
BACKGROUND OF THE INVENTION
In the course of testing and preparing subterranean oil and gas wells for production, a well packer is run into the well on a work string or production tubing. The packer is used: (a) to support the production tubing and the other completion equipment such as filter screens adjacent to a producing formation, and (b) to seal the annulus between the outside of the production tubing and the inside of the well casing, thus blocking movement of fluids through the annulus past the packer location. The packer is equipped with anchor slips that have opposed camming surfaces that cooperate with complementary opposed wedging surfaces. The anchor slips are radially extendable into gripping engagement against the well casing bore in response to relative axial movement of the wedging surfaces. The packer also carries annular seal elements that are expandable radially into sealing engagement against the bore of the well casing in response to axial compression forces. Hydraulic or mechanical means may be used to set the anchor slips and the sealing elements.
After the packer has been set and sealed against the well casing bore, it is designed to maintain the seal after the hydraulic or mechanical setting force is removed. It is absolutely essential that the packer remain locked in its set and sealed configuration while withstanding hydraulic pressures that may be applied from the formation and/or the manipulation of the tubing string and service tools. In deep wells this may be much more difficult as the packer and its components are subjected to downhole temperatures as high as 600° F., and downhole pressures of up to 10,000 psi. Moreover, the packer should be able to withstand the application of external hydraulic pressures at levels up to as much as 10,000 psi in either direction, and still be retrievable after exposure for periods of 10 to 15 years or more. After such long periods of extended service under extreme pressure and temperature conditions, it is desirable that the packer be retrievable from the well. Appropriate manipulation of the tubing string must cause the packer to be released and unsealed from the well bore, with the anchor slips and seal elements being retracted sufficiently to avoid seizure against well bore restrictions that are smaller than the retracted seal assembly, for example, at a makeup union, collar union, nipple, etc.
Currently, permanent and retrievable packers are used for long-term placement in high temperature, high pressure wells. While so-called permanent packers exist, most are still designed to be retrievable through some form of manipulation to release the packer elements and anchor slips, with the packer then to be removed from the well bore. However, since the packers are threaded into the production tubing and are held in firm contact with the well casing, the problem of how to retrieve them occurs. Conventionally, retrievable packers have been removed from the well by first removing all of the production tubing from a threaded joint at the top of the packer to be removed. Then, a new work string with a releasing tool attached is introduced into the well. The releasing tool attaches to the threaded coupling on the top of the packer and operates the release mechanism of the packer. The packer is then retrieved by a tensile force applied to the work string transferred to the packer at the threaded coupling. However, the extra operation of removing the production tubing from above the packer before the packer can be released and retrieved is expensive in time and manpower to accomplish.
Therefore, what is needed in the art is a slick line packer release system that simplifies the locating, release and retrieval of a set packer without removing the production tubing.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides a packer releasing tool for releasing a packer from a wellbore where the packer is coupled to a tubing string and has a releasing profile with a packer uphole shoulder and a packer downhole shoulder. In one embodiment, the packer releasing tool comprises a toplock assembly that is movably coupled to a downlock assembly and a toplock key that is movably coupled to the toplock assembly and that has a toplock key profile engageable against the packer releasing profile. This embodiment further includes a downlock lug that is movably coupled to the downlock assembly and that has a downlock lug profile engageable against the packer releasing profile. In one preferred embodiment, the packer releasing tool has an outer diameter that is less than the inner diameter of the tubing string. This unique configuration allows the packer to be released without the need of first removing the production string.
In another embodiment, the toplock key includes an inner profile and the toplock assembly further comprises a running profile configured to cooperatively engage the inner profile and receive the toplock key therein as the packer releasing tool is run into the wellbore. In another aspect of this particular embodiment, the toplock assembly further comprises a pulling profile configured to cooperatively engage the inner profile and receive the toplock key therein when the packer releasing tool is pulled from the wellbore. In another aspect of this particular embodiment, the toplock assembly further comprises a toplock carrier and a mandrel. The toplock carrier is movable with respect to the mandrel, and the toplock assembly further includes a key releasing shear pin coupling the toplock carrier to the mandrel. The key releasing shear pin limits the range of motion of the toplock carrier with respect to the mandrel. In yet another aspect of this particular embodiment, the mandrel includes a mandrel stop shoulder and the toplock carrier includes a carrier shoulder configured to engage the mandrel stop shoulder and prevent a movement of the toplock carrier with respect to the mandrel. The packer releasing tool may further comprise a toplock assembly spring configured to exert a downhole force against the toplock carrier and move the toplock carrier downhole with respect to the mandrel to allow the inner profile of the key to engage the pulling profile when the key releasing shear pin is sheared.
In another embodiment, the toplock assembly is removably coupled to the downlock assembly by an assembly shear pin. The shear pin is preferably configured to shear when a sufficient amount of force is exerted against the shear pin, which allows the toplock assembly to separate from the downlock assembly.
In another embodiment, the downlock assembly includes a downlock lug running profile configured to cooperatively receive the downlock lug therein as the packer releasing tool is run into the wellbore. The toplock key profile may further include a toplock key uphole stop shoulder configured to engage the packer uphole shoulder and a toplock key downhole stop shoulder configured to engage the packer downhole shoulder. In another embodiment, the downlock lug profile includes a downlock lug uphole stop shoulder configured to engage the packer uphole shoulder and a downlock lug downhole stop shoulder configured to engage the packer downhole shoulder.
In a further embodiment, the packer releasing tool comprises an extension rod extending through the toplock assembly and the downlock assembly. The extension rod is movable with respect to the toplock assembly and engageable against the downlock assembly to separate the downlock assembly from the toplock assembly. In another aspect of this particular embodiment, a downhole power unit is coupled to the extension rod and is configured to exert a downhole force against the downlock assembly by way of the extension rod. In yet another aspect of this particular embodiment, the packer releasing tool further com
Gazda Imre I.
Kilgore Marion D.
Rood Dennis D.
Gaines Charles W.
Halliburton Energy Service,s Inc.
Herman Paul I.
Suchfield George
LandOfFree
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