Retrievable high pressure, high temperature packer apparatus with anti-extrusion system and method

Information

  • Patent Grant
  • 6318460
  • Patent Number
    6,318,460
  • Date Filed
    Friday, May 19, 2000
    24 years ago
  • Date Issued
    Tuesday, November 20, 2001
    23 years ago
Abstract
A packer apparatus for sealing between a tubing string and a casing in a wellbore is disclosed. The packer apparatus includes a seal assembly disposed about a packer mandrel. Upper and lower seal wedges are disposed about the packer mandrel above and below the seal assembly and may be inserted between the seal assembly and the packer mandrel to radially expand the seal assembly into engagement with the casing. The seal assembly includes an expandable elastomeric seal element having anti-extrusion bridge elements disposed in recesses at the upper and lower ends thereof. The anti-extrusion elements form an almost complete circle and thus are arcuately shaped having first and second ends with a gap therebetween. The anti-extrusion bridge elements are preferably automatically radially retractable elements so that when the seal wedges are removed from between the seal assembly and the packer mandrel, the automatically radially retractable anti-extrusion elements will apply a radially inwardly directed force sufficient to cause the seal assembly to radially retract and close around the packer mandrel.
Description




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.











BRIEF DESCRIPTION OF THE DRAWINGS





FIGS. 1A-1F

show a partial cross-section elevation view of the packer apparatus of the present invention in a running position.





FIGS. 2A-2F

show a partial cross-section elevation view of the packer apparatus of the present invention in a set position.





FIG. 3

is a top plan view of the seal assembly of the present invention.





FIG. 4

shows a section view taken from lines


4





4


of FIG.


3


.





FIG. 5

shows a plan view of an anti-extrusion element of the present invention.





FIG. 6

shows a cross-sectional view from lines


6





6


.





FIG. 7

shows a cross-sectional view of a drag block sleeve showing the J-slot.





FIG. 8

is a bottom plan view of the seal assembly of the present invention.





FIGS. 9A and 9B

show a schematic portion of the packer apparatus set in a casing disposed in a wellbore.





FIG. 10

shows the development of one J-slot of the present invention.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




Certain terminology may be used in the following description for convenience only and is not limiting. For instance, the words “inwardly” and “outwardly” are directions toward and away from, respectively, the geometric center of a referenced object.




Referring now to the drawings and more specifically to

FIGS. 1A-1F

and


2


A-


2


F, a packer apparatus


10


is shown. Packer apparatus


10


is shown schematically in

FIGS. 9A and 9B

as part of a tubing string


11


disposed in a wellbore


12


. Wellbore


12


has a casing


13


with an inner surface


14


disposed therein. Packer apparatus


10


may have an upper end


15


which has internal threads


16


defined thereon adapted to be connected to tubing string


11


which extends thereabove, and may further include a lower end


20


having threads


21


defined thereon for connecting with tubing string


11


which will extend therebelow. Thus, packer apparatus


10


is adapted to be connected to and made up as part of a tubing string


11


.




Tubing string


11


above and below packer apparatus


10


may be production tubing or any other known work or pipe string, and may include any kind of equipment and/or tool utilized in the course of treating and preparing wells for production. It is also understood that the packer apparatus


10


will support production tubing and other production equipment such as a screen adjacent a producing formation and will seal the annulus between the outside of the production tubing and the inside of a well casing disposed in a wellbore. Packer apparatus


10


defines a central flow passage


32


for the communication of fluids through packer apparatus


10


and tubing string


11


thereabove and therebelow.





FIGS. 1A-1F

show packer apparatus


10


in a first or running position


25


and

FIGS. 2A-2F

show packer apparatus


10


in a second or set position


30


.

FIGS. 1C

,


1


E,


2


C and


2


E schematically show a cross section of casing


13


. It is understood that casing


13


extends in a downward and upward direction in wellbore


12


, but is not shown in

FIGS. 1A

,


1


B,


1


D,


1


F,


2


A,


2


B,


2


D and


2


F for the sake of clarity.




Packer apparatus


10


includes a packer mandrel


35


with an upper end


40


and a lower end


45


. Lower end


45


comprises lower end


20


of the packer apparatus and has threads


21


. Upper end


40


may be threadably connected to a hydraulic hold-down assembly


50


which has threads


16


defined therein adapted to be connected to the tubing string, thereby adapting packer mandrel


35


to be connected in tubing string


11


. Packer mandrel


35


may comprise an upper packer mandrel


55


and a lower packer mandrel


60


.




Upper packer mandrel


55


has an upper end


62


and a lower end


64


which may be threadedly connected to lower packer mandrel


60


at its upper end


66


thereof. Lower packer mandrel


60


has a lower end


67


. Upper mandrel


55


has first, second and third inner surfaces


68


,


70


and


72


defining first, second and third diameters


74


,


76


and


78


, respectively. Inner surface


70


is recessed radially inwardly from surface


68


, and surface


72


is recessed radially inwardly from surface


70


. A volume tube


80


is sealingly received in second inner surface


70


near the lower end


64


of upper packer mandrel


55


. Volume tube


80


extends upwardly through upper mandrel


55


and sealingly engages an inner surface


82


of hydraulic hold-down assembly


50


. Volume tube


80


thus defines a portion of central flow passage


32


which extends longitudinally through packer apparatus


10


.




Upper packer mandrel


55


has an outer surface


86


defined thereon defining a first outer packer diameter


88


. Outer surface


86


may also be referred to as a seal-supporting surface


86


. Packer apparatus


10


further includes a radially expandable seal assembly


90


disposed about packer mandrel


35


. As shown in

FIGS. 1A-1F

, seal assembly


90


is closely received about outer packer surface


86


.




Seal assembly


90


has an outer or first axial surface


92


and an inner or second axial surface


94


defining inner diameter


93


. A gap


95


exists between first axial surface


92


and casing


13


when packer apparatus


10


is in running position


25


. Seal assembly


90


also has a first or upper end


96


and a second or lower end


98


with a length


99


therebetween. First end


96


defines a first or upper radial surface


100


and second end


98


defines a second or lower radial surface


102


. Inner surface


94


of seal assembly


90


is closely received about and preferably engages outer packer surface, or seal-supporting surface


86


along the entire length


99


thereof when packer apparatus


10


is in running position


25


.




Seal assembly


90


may comprise a sealing element


104


having a outer or first axial surface


106


and a second or inner axial surface


108


. Sealing element


104


is preferably formed from an elastomeric material such as, but not limited to, NBR, FKM, VITON® or the like. However, one skilled in the art will recognize that depending on the temperatures and pressures to be experienced, other materials may be used without departing from the scope and spirit of the present invention.




Sealing element


104


has a first or upper end


110


and a second or lower end


112


. First end


110


defines a first or upper radial surface


114


and second end


112


defines a second or lower radial surface


116


. Seal assembly


90


further includes anti-extrusion jackets


117


which may comprise a first or upper anti-extrusion jacket or element


118


and a second or lower anti-extrusion jacket or element


120


.




The details of the anti-extrusion jackets are shown in

FIGS. 3

,


5


,


6


and


8


. As shown therein, anti-extrusion jackets


118


and


120


are substantially identical in configuration, and so will be referred to collectively as anti-extrusion jackets or elements


117


. As will be explained hereinbelow, however, the radial position of the upper jacket


118


in seal assembly


90


is different from the radial position of the lower jacket


120


. Anti-extrusion jackets


117


are circular, or ring shaped, but do not form a complete circle. Jackets


117


are thus arcuately shaped anti-extrusion jackets having first and second ends


122


and


124


defining a gap


123


therebetween. Anti-extrusion jackets


117


may also be defined or described as toroid or doughnut shaped having a circumferential gap or split


123


therein which defines first and second ends


122


and


124


.




As shown in

FIG. 6

, anti-extrusion jackets


117


have a generally rectangularly shaped cross section with outer surface


130


, inner surface


132


and opposed side surfaces


134


. Anti-extrusion jackets


117


may have first and second tongues


136


and


138


, respectively, extending radially inwardly from inner surface


132


. First tongue


136


has a first end


140


and a second end


142


. Second tongue


138


has a first end


144


and a second end


146


. First ends


140


and


144


of first and second tongues


136


and


138


have an arc length


148


therebetween which preferably is greater than 60° but less than 70°, but may vary and be less or greater than 60-70° depending on the diameter of the jackets. A groove


150


is defined in outer surface


130


and preferably extends from first end


122


around the entire circumference of anti-extrusion jackets


117


to second end


124


.




Preferably, outer surface


130


of anti-extrusion jackets


117


is coextensive with outer surface


106


of sealing element


104


so that surfaces


106


and


130


comprise outer surface


92


of seal assembly


90


. Additionally, the exposed surfaces


134


of jackets


117


are preferably coextensive with the upper and lower radial surfaces


114


and


116


of sealing element


104


. Thus, exposed surfaces


134


and radial surfaces


114


and


116


of sealing element


104


define upper and lower radial surfaces


100


and


102


of seal assembly


90


.




Referring now to

FIG. 4

, anti-extrusion jackets


117


are received in recesses


152


defined in sealing element


104


. Recesses


152


which may be referred to as circumferential recesses, comprise a first or upper recess


154


and a second or lower recess


156


. First recess


154


defines a first recessed surface


155


and second recess


156


defines a second recessed surface


157


. Recess


154


has a first arcuate portion


158


and a second arcuate portion


160


. Recessed surface


155


is substantially L-shaped at first arcuate portion


158


and thus includes a leg


162


, which may be referred to as axial leg


162


, extending axially from upper end


110


and a leg


164


, referred to as radial leg


164


, extending radially inwardly from outer surface


106


until it intersects axial leg


162


. Radially inwardly extending grooves


166


, having a slightly greater arc length than tongues


136


and


138


, are defined in leg


162


of recessed surface


155


so that tongues


136


and


138


may be received therein.




Recessed surface


155


is also generally L-shaped at second arcuate portion


160


. Recessed surface


155


at second portion


160


has a leg


168


, referred to as radial leg


168


, extending radially inwardly from outer surface


106


of seal element


104


. Leg


168


extends radially inwardly a greater distance than leg


164


. A leg


170


, referred to as axial leg


170


, extends axially from upper end


110


until it intersects with leg


168


. Leg


170


extends axially a greater distance than leg


162


of first portion


158


of recessed surface


155


.




Recess


156


at lower end


112


of sealing element


104


defines recessed surface


157


, and includes a first arcuate portion


172


and a second arcuate portion


174


. Recessed surface


157


is generally L-shaped at both first and second portions


172


and


174


. At first portion


172


, recessed surface


157


has a leg


175


, referred to as axial leg


175


, extending axially from lower end


112


and a leg


176


, referred to as radial leg


176


, extending radially inwardly from outer surface


106


until it intersects axial leg


175


. Radially inwardly extending grooves


177


, having a slightly greater arc length than tongues


136


and


138


, are defined in leg


175


of recessed surface


157


so that tongues


136


and


138


may be received therein.




Recessed surface


157


at second arcuate portion


174


has a leg


178


, referred to as axial leg


178


, extending axially from lower end


112


and a leg


180


, referred to as radial leg


180


, extending radially inwardly from outer surface


106


until it intersects axial leg


176


. Legs


178


and


180


have lengths greater than legs


175


and


176


, respectively. Second portion


174


of lower recess


156


is positioned radially 180° from second portion


160


of first recess


154


and second portions


160


and


174


each preferably span between 60° and 70°, but the actual angle may vary and be greater or less than 60°-70°, depending on seal element outer diameter.




Bridge elements


182


and


184


are received in recesses


154


and


156


at second portions


160


and


174


, respectively. As shown in

FIG. 4

, bridge elements


182


and


184


preferably have substantially L-shaped cross sections and thus define L-shaped surfaces


183


and


185


, respectively. The bridge elements are preferably made from heat-treated steel. Surface


183


is substantially coextensive with recessed surface


155


of first portion


158


of upper recess


154


. Surface


185


is substantially coextensive with recessed surface


157


of first portion


172


of lower recess


156


.




As shown in

FIGS. 3 and 10

, upper and lower jackets


118


and


120


are disposed in recesses


154


and


156


, respectively, so that gap


123


in upper jacket


118


is aligned with bridge element


182


, and gap


123


in lower jacket


120


is rotated approximately 180° therefrom and aligned with bridge element


184


.




As described earlier, second portions


160


and


174


of recesses


154


and


156


, respectively, preferably extend between 60° and 70°, so the L-shaped bridge elements likewise span between 60° and 70° but will have an arcuate length slightly less than the arcuate lengths of second portions


160


and


174


. The gaps


123


in upper and lower anti-extrusion jackets


118


and


120


are preferably positioned at the approximate center of the arcuate length of bridge elements


182


and


184


, respectively, when the packer apparatus


10


is in running position


25


. The arcuate length of gap


123


will be smaller than the arcuate length of bridge elements


182


and


184


when seal assembly


90


is radially expanded to engage casing


13


. Thus, ends


122


and


124


of the anti-extrusion jackets will always be disposed in bridge elements


82


and


184


and will never reach the ends of the bridge elements.




Packer apparatus


10


further includes first, or upper and second, or lower pusher shoes


196


and


198


, respectively, and first, or upper and second, or lower seal wedges


200


and


202


, respectively. Upper seal wedge


200


has an inner surface


204


defining an inner diameter


206


, and is closely and sealingly received about upper packer mandrel


55


. Upper seal wedge


200


is threadably connected at a joint


208


to upper packer mandrel


55


at an upper end


209


thereof, and has a lower end


210


that is positioned above upper end


96


of seal assembly


90


when packer apparatus


10


is in running position


25


. Upper seal wedge


200


has a first outer, or seal engagement surface


212


defining a first outer diameter


213


stepped radially outwardly from surface


86


of packer mandrel


55


. A ramp or ramp surface


214


having a ramp angle


215


is provided on upper seal wedge


200


between inner surface


200


and first outer surface


212


.




Upper seal wedge


200


has a second outer surface


216


located above and displaced radially outwardly from outer surface


212


, a third outer surface


218


located above and displaced radially outwardly from second outer surface


216


and a fourth outer surface


220


located above and displaced radially outwardly from third outer surface


218


. Thus, surface


216


defines a diameter


217


having a magnitude greater than diameter


213


, surface


218


defines a diameter


219


having a magnitude greater than diameter


217


and surface


220


defines a diameter


221


having a magnitude greater than the magnitude of diameter


219


.




A first downward facing shoulder


222


is defined between first and second outer surfaces


212


and


216


. A second downward facing shoulder


224


is defined by and extends between second outer surface


216


and third outer surface


218


. Finally, a third downward facing shoulder


226


is defined by and extends between third and fourth outer surfaces


218


and


220


, respectively. Upper seal wedge


200


has a fifth outer surface


227


located above and recessed radially inwardly from fourth outer surface


226


. An upward facing shoulder


228


is defined by and extends between surfaces


220


and


227


.




Upper pusher shoe


196


is disposed about upper seal wedge


200


and has a first or upper end


230


, a second or lower end


232


, an outer surface


234


and an inner surface


236


defining a first inner diameter


238


. Outer surface


234


is preferably coextensive with outer surface


92


of seal assembly


90


when packer apparatus


10


is in running position


25


. Pusher shoe


196


is slidable relative to upper seal wedge


200


, and is disposed thereabout so that inner surface


236


sealingly engages fourth outer surface


220


of upper seal wedge


200


.




Pusher shoe


196


has a first or upper head portion


240


defined at the upper end thereof and a second or lower head portion


242


defined at the lower end thereof. Upper head portion


240


defines a second inner diameter


246


radially recessed inwardly from first inner diameter


238


and which has a magnitude smaller than outer diameter


221


defined by fourth outer surface


220


of upper seal wedge


200


. Lower head portion


242


defines a third inner diameter


248


radially recessed inwardly from first inner diameter


238


. Thus, a downward facing shoulder


247


is defined by and extends between diameters


246


and


238


, and an upward facing shoulder


249


is defined by and extends between diameters


238


and


248


. An anti-extrusion lip


250


extends radially inwardly from head portion


242


and engages upper radial surface


100


of seal assembly


90


.




An upper biasing means


252


is disposed about upper seal wedge


200


above pusher shoe


196


. Biasing means


252


may comprise a spring


254


disposed between hydraulic hold-down assembly


50


and upper pusher shoe


196


. The lower portion of hydraulic hold-down assembly


50


may be referred to as a stop ring


256


which engages an upper end


258


of spring


254


. A lower end


260


of spring


254


is adapted to engage the upper end


230


of pusher shoe


196


. Spring


254


is always in compression and thus urges pusher shoe


196


downward so that lower end


232


thereof is in constant engagement with seal assembly


90


both in the running and set positions


25


and


30


, respectively.




Lower seal wedge


202


has an upper end


270


, a lower end


272


and an inner surface


274


defining an inner diameter


276


. Lower seal wedge


202


is closely received about and sealingly engages upper packer mandrel


55


. Upper end


270


of seal wedge


202


is positioned below lower end


98


of seal assembly


90


when packer apparatus


10


is in running position


25


.




Lower seal wedge


202


has a first outer or angular seal engaging surface


278


which may be referred to as a ramp or ramp surface


278


. Ramp surface


278


extends downward from upper end


270


of seal wedge


202


and radially outwardly from inner surface


274


thereof, and thus radially outwardly from outer surface


86


of upper packer mandrel


55


. Ramp surface


278


may have a first ramp portion


280


having a ramp angle


282


and a second ramp portion


284


extending downwardly from first ramp portion


280


and having a second ramp angle


286


. Ramp


278


and terminates at an upward facing shoulder


288


. Preferably, the radially outermost part of ramp


278


, where ramp


278


intersects shoulder


288


, defines a diameter substantially equivalent to or slightly less than diameter


213


of surface


212


of upper seal wedge


200


.




Lower seal wedge


202


has a second outer surface


292


defining a diameter


294


. Shoulder


288


extends between ramp surface


278


and second outer surface


292


. Second outer surface


292


extends downwardly from shoulder


288


and terminates at an upward facing shoulder


296


which is defined by and extends between second outer surface


292


and a third outer surface


298


. Third outer surface


298


defines an outer diameter


300


. Third outer surface


298


extends downwardly from shoulder


296


and terminates at an upward facing shoulder


302


which is defined by and extends between third outer surface


298


and a fourth outer surface


304


which defines a diameter


306


. Fourth outer surface


304


extends downwardly and terminates at a downward facing shoulder


312


defined by and extending between surface


304


and a fifth outer surface


308


. Fifth outer surface


308


defines a diameter


310


recessed radially inwardly from diameter


306


.




Lower pusher shoe


198


is disposed about and slidable relative to lower seal wedge


202


, and has a first inner surface


318


defining a first inner diameter


320


closely received about and sealingly engaged with fourth outer surface


304


of lower seal wedge


202


. Lower pusher shoe


198


has an outer surface


314


defining an outer diameter


316


. Outer surface


314


is preferably coextensive with outer surface


92


of seal assembly


90


when packer apparatus


10


is in running position


25


. Lower pusher shoe


198


has a first or upper end


322


and a second or lower end


324


. A first or upper head portion


326


is defined at first end


322


and a second or lower head portion


328


is defined at lower end


324


. First or upper head portion


326


defines a second inner diameter


330


recessed radially inwardly from first inner diameter


320


. Second or lower head portion


328


defines a third inner diameter


332


radially recessed inwardly from first inner diameter


320


. Thus, a downward facing shoulder


334


is defined by and extends between first and second diameters


320


and


330


, and a upward facing shoulder


336


is defined by and extends between first inner diameter


320


and third inner diameter


332


. A lower anti-extrusion lip


337


extends radially inwardly from upper head portion


326


and engages lower radial surface


102


of seal assembly


90


.




Lower seal wedge


202


is threadedly connected at its lower end


272


to a stop ring


340


at a threaded joint


338


. Stop ring


340


has an outer surface


342


stepped radially outwardly from fifth outer surface


308


of lower seal wedge


202


and has an upper end


344


. A biasing means


346


is disposed about lower seal wedge


202


and is positioned between lower pusher shoe


198


and upper end


344


of stop ring


340


. Biasing means


346


may comprise a spring


348


having an upper end


350


and a lower end


352


. Spring


348


is in compression when packer apparatus


10


is in running position


25


to urge pusher shoe


198


upwardly so that upper end


322


thereof is in constant engagement with radial surface


102


defined by lower end


98


of seal assembly


90


.




Stop ring


340


is connected at a lower end


353


thereof to a slip assembly


354


that is in turn connected to a drag block assembly


356


. Slip assembly


354


and drag block assembly


356


are of a type known in the art. Thus, slip assembly


354


may include a slip wedge


358


disposed about packer mandrel


35


and a plurality of slips


360


disposed about slip wedge


358


. A lower end


362


of slip wedge


354


may engage a generally upwardly facing shoulder


364


defined on the outer surface of packer mandrel


55


when packer apparatus


10


is in running position


25


. Shoulder


364


preferably extends around the entire circumference of packer mandrel


55


. Packer mandrel


55


may also have a pair of lugs


366


having upper and lower ends


365


and


367


, respectively, defined on the outer surface thereof and positioned 180° apart. Thus, slip wedge


358


, which is slidable relative to mandrel


55


may have slots therein to allow wedge


358


to slide relative to the packer mandrel. Such a configuration and the operation thereof are well known in the art.




Slip assembly


354


may be connected to drag block assembly


356


with a split ring collar


363


. Drag block assembly


356


preferably includes four drag blocks


370


, and includes a drag block sleeve


372


with a pair of automatic J-slots


374


defined therein. J-slots have a short leg


380


and a long leg


382


. A pair of radially outwardly extending lugs


376


are defined on lower packer mandrel


60


. As is known in the art, lugs


376


are preferably disposed 180° apart and rest in short legs


380


of J-slots


374


when packer apparatus


10


is in running position


25


. A typical drag block sleeve, with automatic J-slots


374


is shown in cross section in

FIG. 7. A

development of the J-slots is shown in FIG.


10


. The dashed lines in

FIG. 10

indicate that the long leg may not be machined completely through, but need only be deep enough to allow the lugs


376


to travel up and down therein.




The operation of the packer apparatus


10


is as follows. Packer apparatus


10


is lowered on tubing string


11


into wellbore


12


having casing


13


disposed therein. The drag blocks


370


engage inner surface


14


of casing


13


as packer apparatus


10


is lowered into the wellbore. Once packer apparatus


10


has reached the location in wellbore


12


where it is desired to move packer apparatus


10


to set position


30


, tubing string


11


is pulled upwardly, which causes the hydraulic hold-down assembly


50


and thus the packer mandrel


35


to be pulled upward. Friction between drag blocks


370


and casing


13


holds drag block assembly


356


in place while the packer mandrel is moved upwardly. Packer mandrel


35


is moved upward and rotated so that lugs


376


are positioned above long legs


382


of J-slots


374


. The upward pull is then released and packer mandrel


35


is allowed to move downwardly. Upper seal wedge


200


is fixedly connected to packer mandrel


35


so that as packer mandrel


35


moves downwardly, seal wedge


200


likewise moves downwardly. Upper spring


254


will urge pusher shoe


200


downwardly which in turn causes a downward force on seal assembly


90


and lower pusher shoe


202


. The downward force is transmitted into lower spring


348


which urges stop ring


340


and thus wedge


358


downward. As wedge


358


moves downward, it expands slips


360


outwardly until the slips ultimately engage and grab casing


13


.




Packer mandrel


35


continues to move downwardly after slips


360


engage casing


13


. Lower end


210


of upper seal wedge


200


will engage and begin to slide between seal assembly


90


and outer surface


96


of packer mandrel


55


, thus expanding seal assembly


90


radially outwardly. As the packer mandrel continues to move downward, upper seal wedge


200


and upper pusher shoe


196


, which is being urged downward by spring


254


, will also cause seal assembly


90


to slide downwardly. Because lower seal wedge


202


is slidable relative to upper packer mandrel


55


, and is fixed in place and cannot move downward in set position


30


, seal assembly


90


will engage upper end


270


of lower seal wedge


202


and will slide over ramp surface


278


as seal assembly


90


is urged downwardly.




Because the packer apparatus has both upper and lower seal wedges, the outer surface


92


of the seal assembly


90


is encouraged to engage the casing first at the upper and lower ends


96


and


98


thereof. As the packer mandrel continues to move downwardly, upper and lower seal wedges


200


and


202


will slide between and thus be inserted between seal assembly


90


and surface


86


of upper packer mandrel


55


so that inner surface


94


thereof is engaged by ramp surface


214


and first outer or seal engagement surface


212


of upper seal wedge


200


, and by ramp surface


278


of lower seal wedge


202


. The upper and lower seal wedges thus radially expand the inner diameter of seal assembly


90


which forces the seal assembly


90


radially outwardly into engagement with the casing


13


. Upper and lower seal wedges


200


and


202


each will be inserted between seal assembly


90


and outer surface


96


of upper packer mandrel


35


for at least a portion of length


99


, and upper seal wedge


200


preferably extends for at least one-half the length of seal assembly


90


when packer apparatus


10


is in set position


30


.




In the set position, anti-extrusion lip


250


on upper pusher shoe


196


will engage shoulder


224


on upper seal wedge


200


and anti-extrusion lip


337


on lower pusher shoe


198


engages shoulder


296


on lower seal wedge


202


. Thus, in the set position, seal assembly


90


is engaged by ramp surface


214


, seal surface


212


, and shoulder


222


of seal wedge


200


, and is engaged also by anti-extrusion lip


250


and lower head portion


242


of pusher shoe


196


. Shoulder


222


, anti-extrusion lip


250


and head portion


242


provide a substantially continuous surface at upper end


96


of seal assembly


90


with no gaps to prevent any seal extrusion.




Seal assembly


90


is also engaged in the set position by ramp surface


278


and shoulder


288


on lower seal wedge


202


, and by anti-extrusion lip


337


and upper head portion


326


of lower pusher shoe


198


, which provides a substantially continuous surface in the set position to prevent any seal extrusion at the lower end


93


of seal assembly


90


. when packer apparatus


10


is in set position


30


, gap


123


between ends


122


and


124


of anti-extrusion jackets


118


and


120


will increase but will still define an arcuate length less than the arcuate length of bridge elements


182


and


184


. Thus, bridge elements


182


and


184


will engage the casing at the location of the gaps


123


in the anti-extrusion jackets so that bridge elements


182


and


184


and anti-extrusion jackets


118


and


120


prevent seal extrusion at the casing


13


. Extrusion of the seal is thus substantially completely prevented because anti-extrusion jackets


118


and


120


, along with bridge elements


182


and


184


, will engage casing


13


to prevent seal extrusion at the casing inner surface and since the jackets and bridge elements, along with the pusher shoes and seal wedges encase the upper and lower ends of the seal element between packer mandrel


35


and casing


13


.




When packer apparatus


10


is in the set position, seal assembly


90


sealingly engages casing and will operate to maintain a seal at temperature and pressure as extreme as 400° F. and 15,000 psi. If it is desired to remove the packer apparatus from the wellbore or to set the packer apparatus at a different location an upward pull is applied so that packer mandrel


35


will begin to slide upwardly. Shoulder


362


on packer mandrel


35


will engage end


364


of slip wedge


358


and will pull wedge


358


up to allow slips


360


to retract radially inwardly and release the grab on casing


13


. Like-wise, upward pull will cause upper seal wedge


200


to be pulled upwardly from between outer surface


86


of upper packer mandrel


55


and seal assembly


90


until lower end


210


thereof is positioned above upper end


96


of seal assembly


90


. Lower spring


348


will urge pusher shoe


202


upwardly as the packer mandrel is moved upwardly and the seal assembly


90


will slide off of ramp surface


278


of lower seal wedge


202


. When lugs


376


reach the top of J-slots


374


, rotation will occur and lugs


376


will be positioned above short legs


380


of J-slots


374


. Packer mandrel


35


can be set back down and lugs


376


will rest in short legs


380


of J-slots


374


. Packer apparatus


10


will be once again in the running position as shown in

FIG. 1A-1F

.




Seal assembly


90


will retract radially when seal wedges


200


and


202


are removed from between packer mandrel


35


and seal assembly


90


. When seal wedges


200


and


202


are completely axially retracted, seal assembly


90


is closely received about packer mandrel


35


and gap


95


is defined between seal assembly


90


and casing


13


. At least one, and preferably both of anti-extrusion jackets


118


and


120


are automatically retractable anti-extrusion jackets which apply a radially inward force sufficient to cause seal assembly


90


to automatically close around packer mandrel


35


when slip wedges


200


and


202


are axially retracted and removed from between packer mandrel


35


and seal assembly


90


. The automatically retractable jackets will apply force directed radially inwardly so that the seal assembly will radially retract until inner surface


94


of seal assembly


90


is closely received about packer mandrel


35


along the entire length


99


thereof. The anti-extrusion jackets


118


and


120


are preferably made from titanium which has strength sufficient to prevent extrusion and has the characteristics necessary to apply the radially inward force required to close seal assembly


90


around packer mandrel


35


such that gap


95


exists between seal assembly


90


and the casing when packer apparatus


10


is in the running position. However, any material having the characteristics and qualities necessary to withstand the extreme temperatures and pressures in the wellbore, and which is capable of repeatedly applying sufficient force directed radially inwardly to cause the seal assembly to retract may be used.




The packer apparatus of the present invention achieves results not possible with prior packers having radially expandable seals. The radially expandable seal shown in U.S. Pat. No. 5,603,511 to Kaiser, Jr., et al. (the “Kaiser patent”), is described as a sealing assembly that maintains sealing engagement at temperatures and pressures of 325° F. and 10,000 psi, respectively. The seal between the casing and tubing in the Kaiser patent is caused by the purely radial expansion of the seals and it does not appear that any compressive forces are imparted into the seal from the axial movement of the packer mandrel. It was found that such an arrangement was not feasible when the seal must maintain engagement at a temperature and pressure of 400° F. and 15,000 psi. The thickness of the seal element required to maintain sealing engagement at such a high temperature and pressure was such that the seal was damaged because the seal wedge was required to travel the entire length of the seal.




The resolution of that problem was to provide the packer apparatus of the present invention which has upper and lower seal wedges that urge the ends of the seal assembly into engagement with the casing first. Seal damage or destruction is not a problem since neither the upper nor lower seal wedge is required to travel the entire length of the seal assembly. The upper seal wedge and lower seal wedge are both inserted between the packer mandrel and the inner surface of the seal along at least a portion of the length of the seal assembly, urging the seal into sealing engagement with the casing by radially expanding the inner diameter of the seal assembly which causes the outer diameter to radially expand and engage the casing.




Once the seal assembly engages the casing, it may be necessary to impart more energy into the seal to insure that the seal assembly


90


will maintain its seal with the casing at 400° F. and 15,000 psi. Sometimes as much as 20,000 pounds downward force or more applied by the tubing string may be required to impart the necessary energy to expand the seal and hold the seal assembly


90


into sealing engagement with the casing at such a high temperature and pressure. When such a downward force is applied, compressive forces applied by the springs, the pusher shoes and by the shoulders and ramped surfaces on the upper and lower seal wedges tend to try to radially expand the seal beyond that which would occur simply due to the radial expansion of the inner diameter of the seal. Such compressive forces provide additional energy which helps to urge and hold the seal assembly


90


in sealing engagement with casing


13


. Thus, the present invention provides a packer apparatus that seals against a casing by applying compressive forces and radially outwardly directed forces to a seal assembly so that radial expansion of the seal assembly creates and maintains sealing engagement with the casing.




Packer apparatus


10


of the present invention can be set numerous times in a wellbore and will successfully maintain sealing engagement with the casing each time it is set in a wellbore at the extreme temperatures and pressures contemplated. Usage of automatically retractable anti-extrusion jackets, which will automatically retract each time the packer apparatus is moved from the set to the running position, is also an improvement over prior art patents in that the prior art discloses jackets which must have an additional spring or other biasing element wrapped therearound to radially retract or close the seal assembly.




Although the intention has been described with reference to a specific embodiment, the foregoing description is not intended to be construed in a limiting sense. Various modifications as well as alternative applications will be suggested to persons skilled in the art by the foregoing specification and illustrations. It is therefore contemplated that the appended claims will cover any such modifications, applications or embodiments as followed in the true scope of this invention.



Claims
  • 1. A packer apparatus for sealing between a tubing string and a casing disposed in a wellbore, the packer apparatus comprising:a packer mandrel adapted to be connected in said tubing string; an expandable sealing element disposed about said packer mandrel, said packer apparatus having a running position and a set position, wherein said sealing element and said casing have a gap therebetween when said packer is in said running position, and wherein said sealing element sealingly engages said casing when said packer is in said set position; and at least one seal wedge disposed about said packer mandrel, wherein said at least one seal wedge will slide between said packer mandrel and at least a portion of said sealing element to expand said seal radially outwardly to sealingly engage said casing when said packer is moved to its set position, and wherein said packer apparatus can be repetitively moved between said set and said running position in said casing without removing said apparatus from said casing, and wherein said sealing element will maintain sealing engagement with said casing each time said packer is moved to said set position.
  • 2. The apparatus of claim 1, wherein said at least one seal wedge will repetitively impart sufficient radial and compressive forces to said sealing element, so that said sealing element will maintain sealing engagement each time said apparatus is moved from said unset to said set position in wellbores having temperatures exceeding 300° F.
  • 3. The apparatus of claim 2, wherein said sealing element will maintain sealing engagement with said casing each time said apparatus is moved from said unset to said set position in wellbores having a pressure exceeding 10,000 psi.
  • 4. The apparatus of claim 3, wherein said sealing element will maintain sealing engagement with said casing each time said apparatus is moved from said unset to said set position in wellbores having a temperature of up to 400° F. and a pressure of up to 15,000 psi.
  • 5. A packer apparatus for sealing between a tubing string and a casing disposed in a wellbore, the packer apparatus comprising:a packer mandrel adapted to be connected in said tubing string; an expandable sealing element disposed about said packer mandrel, said packer apparatus having a running position and a set position, wherein said sealing element and said casing have a gap therebetween when said packer is in said running position, and wherein said sealing element sealingly engages said casing when said packer is in said set position, wherein said packer mandrel is movable relative to said sealing element, and wherein downward movement of said mandrel relative to said sealing element causes radially outwardly directed and compressive forces to be applied to said sealing element so that said sealing element will sealingly engage said casing; and wherein said packer apparatus can be repetitively moved between said set and said running position in said casing, and wherein said sealing element will maintain sealing engagement with said casing each time said packer is moved to said set position.
  • 6. The packer apparatus of claim 5, further comprising at least one seal wedge disposed about said mandrel, wherein said at least one seal wedge imparts at least a portion of said radially outwardly directed and compressive forces to said sealing element when said mandrel is moved downwardly relative to said sealing element.
  • 7. The packer apparatus of claim 6, further comprising:an upper seal wedge disposed about said mandrel above said sealing element; and a lower seal wedge disposed about said mandrel below said sealing element, wherein said upper and lower seal wedges impart said compressive and radially outwardly directed forces to said sealing element when said mandrel moves downwardly relative to said sealing element.
  • 8. A packer apparatus for sealing between a tubing string and a casing disposed in a wellbore, the packer apparatus comprising:a packer mandrel adapted to be connected in said tubing string; an expandable sealing element disposed about said packer mandrel, said packer apparatus having a running position and a set position, wherein said sealing element and said casing have a gap therebetween when said packer is in said running position, and wherein said sealing element sealingly engages said casing when said packer is in said set position; an upper seal wedge disposed about said mandrel; and a lower seal wedge disposed about said mandrel, wherein said upper and lower seal wedges will slide between said sealing element and said mandrel to expand said sealing element radially outwardly when said packer is moved to its set position, wherein said packer apparatus can be repetitively moved between said set and said running position in said casing, and wherein said sealing element will maintain sealing engagement with said casing each time said packer is moved to said set position.
  • 9. A packer apparatus for sealing between a tubing string and a casing disposed in a wellbore, the packer apparatus comprising:a packer mandrel adapted to be connected in said tubing string; an expandable sealing element disposed about said packer mandrel, said packer apparatus having a running position and a set position, wherein said sealing element and said casing have a gap therebetween when said packer is in said running position, and wherein said sealing element sealingly engages said casing when said packer is in said set position, wherein said packer apparatus can be repetitively moved between said set and said running position in said casing, and wherein said sealing element will maintain sealing engagement with said casing each time said packer is moved to said set position; a first anti-extrusion jacket disposed at an upper end of said sealing element; and a second anti-extrusion jacket disposed at a lower end of said sealing element.
  • 10. A packer apparatus for sealing between a tubing string and a casing disposed in a wellbore, the packer apparatus comprising:a packer mandrel adapted to be connected in said tubing string; an expandable scaling element disposed about said packer mandrel, said packer apparatus having a running position and a set position, wherein said sealing element and said casing have a gap therebetween when said packer is in said running position, and wherein said sealing element sealingly engages said casing when said packer is in said set position, wherein said packer apparatus can be repetitively moved between said set and said running position in said casing, and wherein said scaling element will maintain sealing engagement with said casing each time said packer is moved to said set position.
  • 11. A method of repeatedly sealing between a tubing and a casing string in a well, the method comprising:providing a packer apparatus comprising a packer mandrel and an expandable sealing element disposed about said mandrel; lowering said packer apparatus on said tubing into said casing to a selected location in said well; setting said packer apparatus to a set position by radially expanding said sealing element to sealingly engage said casing at said selected location; unsetting said packer apparatus by retracting said sealing element so that said sealing element disengages from said casing; and resetting said packer apparatus at least one additional time in said well so that said sealing element is radially expanded to sealingly engage said casing, said setting and resetting steps comprising applying radially outwardly and axially directed forces to said sealing element to cause said sealing element to sealingly engage said casing.
  • 12. The method of claim 11, further comprising moving said mandrel downwardly relative to said sealing element to apply said forces to said sealing element.
  • 13. The apparatus of claim 11 further comprising:inserting seal wedges between said sealing element and said mandrel to apply said radially outwardly directed forces.
  • 14. The apparatus of claim 13, wherein downward force applied to said mandrel causes said wedges to impart at least a portion of said axial forces to said sealing element.
  • 15. The method of claim 11 wherein said radially outwardly and axially directed forces will cause said sealing element to sealingly engage said casing during said setting step and during each additional resetting step in wellbores having temperatures exceeding 300° F. and 10,000 psi.
  • 16. A method of repeatedly scaling between a tubing and a casing string in a well, the method comprising:providing a packer apparatus comprising a packer mandrel and an expandable sealing element disposed about said mandrel; lowering said packer apparatus on said tubing into said casing to a selected location in said well; setting said packer apparatus to a set position by radially expanding said sealing element to sealingly engage said casing at said selected location; unsetting said packer apparatus by retracting said sealing element so that said sealing element disengages from said casing; moving said apparatus in said casing to an additional selected location; and resetting said packer apparatus at least one additional time in said well so that said sealing element is radially expanded to sealingly engage said casing.
  • 17. A method of repeatedly sealing between a tubing and a casing string in a well, the method comprising:providing a packer apparatus comprising a packer mandrel and an expandable sealing element disposed about said mandrel; lowering said packer apparatus on said tubing into said casing to a selected location in said well; setting said packer apparatus to a set position by radially expanding said sealing element to sealingly engage said casing at said selected location; unsetting said packer apparatus by retracting said sealing element so that said sealing element disengages from said casing; resetting said packer apparatus at least one additional time in said well so that said sealing element is radially expanded to sealingly engage said casing; and producing fluid through said tubing after said setting step.
  • 18. A method of repeatedly sealing between a tubing and a casing string in a well, the method comprising:providing a packer apparatus comprising a packer mandrel and an expandable sealing element disposed about said mandrel; lowering said packer apparatus on said tubing into said casing to a selected location in said well; setting said packer apparatus to a set position by radially expanding said sealing element to sealingly engage said casing at said selected location; unsetting said packer apparatus by retracting said sealing element so that said sealing element disengages from said casing; and resetting said packer apparatus at least one additional time in said well so that said sealing element is radially expanded to sealingly engage said casing.
Parent Case Info

This application is a continuation of application Ser. No. 09/083,304, filed May 22, 1998, now U.S. Pat. No. 6,102,117.

US Referenced Citations (20)
Number Name Date Kind
3706342 Woolley Dec 1972
4127168 Hanson et al. Nov 1978
4176715 Bigelow et al. Dec 1979
4349205 McGee et al. Sep 1982
4457369 Henderson Jul 1984
4515213 Rogen et al. May 1985
4765404 Bailey et al. Aug 1988
5176217 Luke et al. Jan 1993
5277253 Giroux et al. Jan 1994
5311938 Hendrickson et al. May 1994
5348087 Williamson, Jr. Sep 1994
5390735 Williamson, Jr. Feb 1995
5400855 Stepp et al. Mar 1995
5433269 Hendrickson et al. Jul 1995
5511620 Baugh et al. Apr 1996
5526878 Duell et al. Jun 1996
5603511 Keyser, Jr. et al. Feb 1997
5701954 Kilgore et al. Dec 1997
5701959 Hushbeck et al. Dec 1997
6102117 Swor et al. Aug 2000
Continuations (1)
Number Date Country
Parent 09/083304 May 1998 US
Child 09/574809 US