Wells – Packers or plugs – With expanding anchor
Reexamination Certificate
2000-05-19
2001-11-20
Schoeppel, Roger (Department: 3672)
Wells
Packers or plugs
With expanding anchor
C166S196000, C166S217000, C166S387000
Reexamination Certificate
active
06318460
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an expandable seal assembly for sealing an annulus between a substantially cylindrical object and a bore of a surrounding cylindrical casing or wall. More particularly, the present invention relates to a packer apparatus with an expandable seal assembly having anti-extrusion jackets for providing a seal between the packer apparatus and the casing in a wellbore, and to prevent sealing element extrusion at high temperatures and pressures.
It is well known that in the course of treating and preparing subterranean wells for production, a well packer is run into a wellbore on a work string or production tubing. The purpose of the packer is to support the work string or production tubing and other completion equipment such as a screen adjacent a producing formation, and to seal the annulus between the outside of the work string or production tubing and the inside of the well casing to prevent movement of fluid through the annulus past the packer location. Various packers are shown in U.S. Pat. No. 5,311,938 to Hendrickson et al., issued May 17, 1994, U.S. Pat. No. 5,433,269 to Hendrickson et al., issued Jul. 18, 1995, and U.S. Pat. No. 5,603,511 issued to Kaiser et al., issued Feb. 18, 1997, the details of all of which are incorporated herein by reference. The packer apparatus typically carries annular seal elements which are expandable into sealing engagement against the bore of the well casing. The seal elements shown in U.S. Pat. Nos. 5,311,938 and 5,348,087 expand radially in response to axial compressive forces while the seal assembly shown in U.S. Pat. No. 5,603,511 is set into sealing engagement by applying a radially outward force to the inner diameter of the seal element which causes the seal element to expand radially outwardly into sealing engagement with the casing.
The Kaiser et al. patent discloses a radially expandable seal assembly that is designed to maintain sealing engagement at temperatures and pressures around 325° F. and 10,000 psi. Because the packer apparatus may often experience pressures and temperatures as high as 15,000 psi and 400° F., a need exists for a retrievable seal assembly that will prevent seal element extrusion and blowout at the casing wall and will maintain a reliable seal between the tubing string and the well casing at a temperature of 400° F. and a differential pressure of 15,000 psi.
SUMMARY OF THE INVENTION
The present invention provides a retrievable packer apparatus that can be moved into a set position from a running position several times in a wellbore and can maintain sealing engagement with the casing disposed in the wellbore each time it is set at a temperature as high as 400° and a pressure as high as 15,000 psi.
The packer apparatus includes a packer mandrel having an outer surface. A seal assembly is disposed about the outer surface of the packer mandrel. An upper seal wedge and lower seal wedge are disposed about the packer mandrel and, in the running position, the upper seal wedge is positioned above the seal assembly and the lower seal wedge is positioned below the seal assembly. When the packer apparatus is in the running position, wherein the packer may be lowered or raised in a wellbore, a gap exists between the casing inner surface and the outer surface of the seal assembly. To radially expand the seal assembly outwardly into sealing engagement with the casing, the packer apparatus is moved from the running to the set position. To do so, the packer mandrel is moved downwardly with respect to the seal assembly, which causes the upper and lower seal wedges to slide between the packer mandrel outer surface and an inner surface of the seal assembly to radially expand the seal assembly outwardly. The seal wedges are capable of radially expanding the seal and are also capable of imparting axial compressive forces into the seal assembly so that the combined radially outward forces and the compressive forces imparted into the seal assembly by the upper and lower seal wedges expand the seal sufficiently such that the seal assembly will maintain sealing engagement with the casing at a temperature as high as 400° F. and a pressure as high as 15,000 psi.
The seal assembly includes a generally cylindrical sealing element and generally annular anti-extrusion jackets received in recesses defined at the upper and lower ends of the sealing element. The recesses extend radially inwardly from the outer surface of the sealing element and intersect the upper and lower ends thereof, so that each recess is generally L-shaped. The anti-extrusion jackets have a generally rectangular cross section and are received in the recesses. The anti-extrusion jackets have a circumferential gap therein so that when the seal assembly is expanded into the set position, the gap in the anti-extrusion jackets expand. A bridge element is received in the recesses between a portion of the anti-extrusion jackets and the sealing element, and is generally in alignment with the gap in the jackets so that when the seal expands, the anti-extrusion jackets and the bridge element will contact the outer wall around the entire outer circumference of the seal element at the upper and lower ends thereof to prevent extrusion. Thus, the anti-extrusion jacket and the bridge element together function as a backup to prevent extrusion. The anti-extrusion jackets are preferably automatically radially retractable and cause the seal assembly to radially retract inwardly when the packer apparatus is moved from the set to the running position.
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Stepp Lee Wayne
Swor Loren C.
Winslow Donald W.
Baball Anthony L.
Halliburton Energy Service,s Inc.
Kent Robert A.
Schoeppel Roger
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