Anti-extrusion device for downhole applications

Information

  • Patent Grant
  • 6598672
  • Patent Number
    6,598,672
  • Date Filed
    Tuesday, October 9, 2001
    23 years ago
  • Date Issued
    Tuesday, July 29, 2003
    21 years ago
Abstract
An anti-extrusion ring for a packer assembly comprises first and second ring portions that are divided into a plurality of discrete arcuate segments. The segments are adapted for movement between a retracted position wherein each segment is in contact with adjacent segments, and an expanded position wherein gaps are formed between the segments. At least one of the ring portions is adapted to face a resilient sealing sleeve of the packer assembly. The first ring portion is circumferentially offset from the second ring portion such that at least one of the first and second ring portions extends across the gaps during movement of the segments toward the expanded position. In this manner, extrusion of the sealing sleeve through the gaps is prevented.
Description




BACKGROUND OF THE INVENTION




This invention relates to downhole devices for subsurface wells or bores, and more particularly to an anti-extrusion ring assembly for downhole packing devices used in elevated temperature and pressure environments.




Expandable packer assemblies are commonly used in the oil and gas industry to seal or close off the annular area between a well bore casing and a drill pipe or tubing. The packer assembly includes a sealing sleeve or packer that is cylindrically shaped and typically has a smaller outer diameter as compared to the inner diameter of the particular casing to be sealed, and is thus easily inserted and positioned within the annular area. Expandable packers may, for example, be constructed of rubber or some other elastomeric material and include a central axial bore through which various types of tools or tubing may be inserted. A mandrel may, for example, be located in the axial bore of the packer, wherein the packer and mandrel are positioned within the casing at a predetermined location and/or depth, in the case of a subterranean well. Activation of the mandrel in combination with upper and lower slip members creates axial compression setting forces which are applied to the axial ends of the packer. The axial compression setting forces cause a reduction in the axial length of the packer and a corresponding increase in the packer outer diameter. As a result, the packer seals against the inner surface of the casing to effectively seal the annular area. An anti-extrusion ring, typically in the form of a split metallic ring, is positioned between the packer and each of the upper and lower slip members. The anti-extrusion rings are intended to prevent extrusion of the packer under elevated temperature and pressure conditions that would otherwise destroy the packer and/or the seal between the packer and the inner wall of the casing.




During use, it may become necessary to remove the packer for various reasons, typically by drilling through the packer and the metallic anti-extrusion rings. Although the elastomeric packer material is relatively easy to drill through, removal of the metallic rings has proven to be more difficult.




SUMMARY OF THE INVENTION




It is therefore an object of the present invention to provide an anti-extrusion ring for a packer assembly that is relatively easy to remove, even after the packer assembly has been set in a casing or other tubing.




It is a further object of the invention to provide an anti-extrusion ring for a packer assembly that is multi-segmented.




According to the invention, an anti-extrusion ring for a packer assembly comprises first and second ring portions that are divided into a plurality of discrete arcuate segments. The segments are adapted for movement between a retracted position wherein each segment is in contact with adjacent segments, and an expanded position wherein gaps are formed between the segments. At least one of the ring portions is adapted to face a resilient sealing sleeve of the packer assembly. The first ring portion is circumferentially offset from the second ring portion such that at least one of the first and second ring portions extends across the gaps during movement of the segments toward the expanded position. In this manner, extrusion of the sealing sleeve through the gaps is prevented.




Further according to the invention, a downhole packer assembly for use in a well bore comprises an elongate mandrel adapted for positioning in the well bore; an expander adapted for sliding movement along the mandrel; a resilient sealing sleeve disposed around the mandrel for engaging the well bore; and at least one anti-extrusion ring disposed between the expander and the sealing sleeve. The at least one anti-extrusion ring comprises first and second ring portions that are divided into a plurality of discrete arcuate segments. The segments are adapted for movement between a retracted position wherein each segment is in contact with adjacent segments, and an expanded position wherein gaps are formed between the segments. At least one of the ring portions contacts the sealing sleeve. The first ring portion is circumferentially offset from the second ring portion such that at least one of the first and second ring portions extends across the gaps during movement of the segments toward the expanded position. In this manner, extrusion of the sealing sleeve through the gaps is prevented.




Other objects and advantages of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.











BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS




The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:





FIG. 1

is a longitudinal sectional view of a packer assembly according to the present invention disposed in a casing in a retracted position;





FIG. 2

is a view similar to

FIG. 1

with the packer assembly in an expanded position against the casing;





FIG. 3

is an isometric view of an anti-extrusion ring according to a first embodiment of the invention that forms part of the packer assembly;





FIG. 4

is a sectional view of the anti-extrusion ring taken along line


4





4


of

FIG. 3

;





FIG. 5

is a side elevational view of the anti-extrusion ring first embodiment in an expanded position;





FIG. 6

is a sectional view of a pair of anti-extrusion rings according to a second embodiment of the invention;





FIG. 7

is a side elevational view of an anti-extrusion ring according to the second embodiment;





FIG. 8

is a top plan view of the anti-extrusion ring of

FIG. 6

;





FIG. 9

is an isometric view of an anti-extrusion ring according to a third embodiment of the invention;





FIG. 10

is a side elevational view of an anti-extrusion ring according to the third embodiment;





FIG. 11

is a sectional view of the anti-extrusion ring third embodiment taken along line


11





11


of

FIG. 10

;





FIG. 12

is a side elevational view of an intermediate ring portion that forms part of the anti-extrusion ring third embodiment;





FIG. 13

is a sectional view of the intermediate ring portion taken along line


13





13


of

FIG. 12

;





FIG. 14

is a side elevational view of an inner ring portion that forms part of the anti-extrusion ring third embodiment;





FIG. 15

is a sectional view of the inner ring portion taken along line


15





15


of

FIG. 14

;





FIG. 16

is side elevational view of a portion of an anti-extrusion ring according to a fourth embodiment of the invention;





FIG. 17

is a sectional view of the anti-extrusion ring portion fourth embodiment taken along line


17





17


of

FIG. 16

;





FIG. 18

is an isometric view of an anti-extrusion ring segment according to the fourth embodiment;





FIG. 19

is a top plan view of the anti-extrusion ring segment; and





FIG. 20

is a side elevational view of the anti-extrusion ring segment.











It is noted that the drawings are merely schematic representations of the invention and depict only typical embodiments thereof. The invention will now be described with additional detail through the accompanying drawings.




DETAILED DESCRIPTION OF THE INVENTION




Referring now to the drawings, and to

FIGS. 1 and 2

in particular, a packer assembly


10


according to the present invention is illustrated. The packer assembly


10


is adapted to seal the annular space


15


between a well casing


12


or other conduit string, and a main body or mandrel


14


. The packer assembly


10


can be lowered in the well casing to the desired setting point by means of a suitable running-in string (not shown), and its parts can be expanded outwardly by a suitable setting apparatus (not shown) in a well-known manner. Setting the packer assembly


10


at a desired location in the casing


12


is described in U.S. Pat. No. 3,036,639, the disclosure of which is hereby incorporated by reference, and therefore will not be further described.




The packer assembly


10


includes a mandrel


14


with an upper frusto-conical expander


20


and a lower frusto-conical expander


22


initially connected to the mandrel by shear screws (not shown) or other attachment means. An upper segmented slip


16


and a lower segmented slip


18


are in turn initially connected to the upper and lower expanders, respectively, by shear screws (not shown) or other attachment means. The upper and lower expanders


20


,


22


are adapted to expand the upper and lower segmented slips


16


,


18


, respectively, into engagement with an inner surface


24


of the casing


12


.




A sealing sleeve


28


is positioned between the expanders


20


,


22


and is constructed of a pliant, elastic material, such as synthetic or natural rubber. As shown in

FIG. 1

, the sealing sleeve


28


is disposed initially in a retracted position free from contact with the inner surface


24


of the casing


12


. An anti-extrusion ring


30


is positioned between the upper expander


20


and an upper end of the sealing sleeve


28


and an anti-extrusion ring


32


is positioned between the lower expander


22


and a lower end of the sealing sleeve


28


. Relative movement of the expanders


20


,


22


toward one another will shorten the axial length of the sealing sleeve


28


and expand it radially outwardly into sealing engagement with the inner surface


24


of the casing


12


, as well as radially inwardly into sealing engagement with the outer surface


34


of the mandrel


14


, as shown in FIG.


2


. The rings


30


and


32


prevent the elastomeric material of the sealing sleeve


28


from flowing and breaking its seal between the inner surface


24


of the casing


12


and the outer surface


34


of the mandrel


14


, which may otherwise occur under high temperature and pressure conditions.




The lower end of the upper expander


20


has a tapered surface


36


that extends in an upward and outward direction. Likewise, the upper end of the sealing sleeve


28


has a tapered surface


38


that extends in a downward and outward direction to thereby form a generally triangular-shaped annular groove


40


into which the ring


30


is received, which is also generally triangular-shaped in cross section. The upper end of the lower expander


22


has a tapered surface


42


that extends in a downward and outward direction. Likewise, the lower end of the sealing sleeve


28


has a tapered surface


44


that extends in an upward and outward direction to thereby form a generally triangular-shaped annular groove


46


into which the ring


32


is received. The rings


30


and


32


are identical in construction, with the ring


32


being installed in a mirror-reverse orientation with respect to the ring


30


.




With reference now to

FIGS. 3 and 4

, the anti-extrusion ring


32


will now be described, it being understood that the anti-extrusion ring


30


is constructed in an identical manner. The ring


32


includes an outer ring portion


50


and an inner ring portion


52


. The outer ring portion


50


has an annular tongue


54


that is slidably received within an annular groove


56


formed in the inner ring portion


52


. Each ring portion


50


and


52


is divided into a plurality of arcuate segments


57


and


58


, respectively. Each segment


57


,


58


includes an arcuate groove


59


that, together with the other respective segments, form a continuous groove that receives an annular biasing member


60


to hold the segments


57


,


58


together. The biasing member


60


is preferably in the form of a continuous tension spring. Alternatively, the biasing member


60


may be in the form of an elastomeric O-ring or other annular biasing member. The outer and inner ring portions


50


,


52


are preferably constructed of a thermoplastic material, such as polyether ether ketone (PEEK), but may be formed of other materials such as polyamide, fiber-reinforced composite material, metal, or other suitable material having high temperature resistance and high sheer strength in order to maintain its shape without significant creeping under high temperature (preferably above 350° F.) and high pressure (preferably above 10,000 psi). In a preferred embodiment, the material can be easily drilled out or otherwise destroyed when it is necessary to remove the packer assembly


10


.




As shown in

FIGS. 3-5

, the segments


57


of the outer ring portion


50


are offset from the segments


58


of the inner ring portion


52


. Due to the biasing members


60


, the segments


57


,


58


normally remain in a retracted position with the ends of each segment


57


,


58


contacting a respective end of adjacent segments


57


,


58


. However, the segments


57


,


58


of the ring portions


50


,


52


are expandable radially outwardly by relative movement between the expanders


20


,


22


and the sealing sleeve


28


(

FIGS. 1 and 2

) to axially shorten and radially expand the sealing sleeve


28


preferably until the segments


57


,


58


are in contact with the inner surface


24


of the casing


12


. During expansion, adjacent segments


57


in the ring portion


50


and adjacent segments


58


in the ring portion


52


separate to form gaps


62


(

FIG. 5

) while the annular tongues


54


slide in the annular grooves


56


to maintain the segments


57


of the outer ring portion


50


offset from the segments


58


of the inner ring portion


52


. In this manner, the gaps


62


of the outer ring portion


50


are maintained in the offset condition with the gaps


62


of the inner ring portion


52


during movement of the anti-extrusion ring between retracted and expanded positions. The offset nature of the gaps


62


effectively prevents extrusion of the sealing sleeve


28


through the rings


30


,


32


which might otherwise occur if the gaps in each ring portion


50


,


52


were aligned.




With particular reference now to

FIGS. 6-8

, anti-extrusion rings


70


and


72


according to a second embodiment of the invention are illustrated, wherein like parts in the previous embodiment are represented by like numerals. The anti-extrusion rings


70


and


72


are identical in construction, with the ring


72


being installed in a mirror-reverse orientation with respect to the ring


70


. Accordingly, the anti-extrusion ring


72


will be described, it being understood that the same description applies to the anti-extrusion ring


70


. The ring


72


includes a relatively thick outer ring portion


74


and a relatively thin inner ring portion


76


. The inner ring portion


76


includes an upper annular flange


78


and a lower annular flange


80


that are slidably received within an upper annular groove


82


and a lower annular groove


84


, respectively, formed in the outer ring portion


74


. The outer ring portion


74


is divided into a plurality of arcuate-shaped outer segments


86


while the inner ring portion


76


is divided into a plurality of arcuate-shaped inner segments


88


that are circumferentially offset from the outer segments


86


. A pair of arcuate grooves


90


are formed in each outer segment


86


, and together with the arcuate grooves


90


of the inner segments


86


, form a pair of continuous grooves


90


that receive an annular biasing member


60


to hold the inner and outer segments


86


,


88


together. Although two biasing members


60


are shown, it will be understood that more or less biasing members may be used. As in the previous embodiment, the outer and inner ring portions


74


,


76


are preferably constructed of a metal or plastic material, such as PEEK, that can withstand high temperature and high pressure conditions associated with downhole environments, and yet can be easily drilled out or otherwise destroyed when it is necessary to remove the packer assembly


10


.




During expansion of the ring


72


, the inner segments


86


separate to form a plurality of gaps


92


(

FIG. 8

) and the outer segments


88


separate to form a plurality of offset gaps


94


while the annular flanges


78


,


80


slide in their respective annular grooves


82


,


84


to maintain the inner segments


86


of the outer ring portion


74


offset from the outer segments


88


of the inner ring portion


76


. In this manner, the gaps


92


of the outer ring portion


74


are maintained in an offset condition from the gaps


94


of the inner ring portion


76


during movement of the anti-extrusion rings


70


,


72


between retracted and expanded positions. The offset nature of the gaps


92


,


94


effectively prevents extrusion of the sealing sleeve


28


through the ring portions


74


and


76


which might otherwise occur if the gaps in each ring portion


74


,


76


were aligned. In addition, the relatively thin inner ring portion


76


decreases the amount of sealing sleeve material that is extruded within the gaps


92


when compared to the relatively thick gaps


62


of the previous embodiment. Thus, the sealing sleeve


28


will deform less in this embodiment than in the previous embodiment.




Referring now to

FIGS. 9-11

, an anti-extrusion ring


100


according to a third embodiment of the invention is illustrated. Although only a single anti-extrusion ring


100


is shown, a further anti-extrusion ring identical in construction to the ring


100


is preferably provided in mirror-reverse orientation so that the rings are positioned between the sealing sleeve


28


(

FIG. 1

) and the upper and lower expanders


20


and


22


, respectively, as previously described with respect to the first and second anti-extrusion ring embodiments. The anti-extrusion ring


100


includes an outer ring portion


102


, an intermediate ring portion


104


, and an inner ring portion


106


connected to the intermediate ring portion


102


for limited relative movement. The inner ring portion


106


is preferably in contact with the seal


28


(

FIG. 1

) while the outer ring portion


102


is preferably in contact with one of the upper and lower expanders


20


,


22


. As in the previous embodiments, each ring portion


104


and


106


is divided into a plurality of offset arcuate segments


108


and


110


, respectively. Each segment


110


includes an arcuate groove


112


that, together with the other respective segments, form a continuous groove that receives an annular biasing member


114


to hold the segments


110


together. The biasing member


114


is preferably in the form of an elastomeric O-ring. Alternatively, the biasing member


114


can be in the form of a continuous tension spring or other annular biasing member.




As shown most clearly in

FIG. 11

, the outer ring portion


102


is preferably of a hollow frusto-conical shape and includes a tapered outer surface


120


and a tapered inner surface


122


. The tapered outer surface


120


is in contact with the tapered surface


36


of the upper expander


20


or the tapered surface


42


of the lower expander


22


, while the tapered inner surface


122


is in contact with a tapered outer surface


124


of the intermediate ring portion


104


.




With additional reference to

FIGS. 12 and 13

, the segments


108


of the intermediate ring portion


104


together form a first wall section


126


that is preferably of a generally hollow frusto-conical shape and a second wall section


128


that extends from the first wall section and is preferably of a generally hollow cylindrical shape. An annular tongue


130


extends from the first wall section


126


. Each segment


108


includes a first aperture


132


that is formed in the first wall section


126


and a second aperture


134


that is formed in the second wall section


128


. Preferably, the first aperture extends normal to the tapered outer surface


124


, while the second aperture extends normal to a surface


136


of the second wall section


128


.




As shown in

FIGS. 14 and 15

, the segments


110


of the inner ring portion


106


together form an annular wall


140


with a tapered outer surface


142


and an annular surface


144


that abut the first wall section


126


and second wall section


128


, respectively, of the intermediate ring portion


104


. An annular depression


146


is formed in the annular wall


140


and is sized for receiving the tongue


130


of the intermediate ring portion


104


. Each segment


110


includes an aperture


148


that is formed in the tapered outer surface


142


and an elongate slot


150


that is formed in the annular surface


144


. Preferably, the aperture


148


extends normal to the tapered outer surface


142


, while the elongate slot


150


extends normal to the annular surface


144


.




With reference again to

FIGS. 10 and 11

, each segment


108


of the intermediate ring portion


104


is circumferentially offset from a segment


110


of the inner ring portion


106


. A connector pin


160


extends through the first aperture


132


of the intermediate ring portion


104


and into the aperture


148


of the inner ring portion


106


to connect each segment


108


with its corresponding offset segment


110


. The connector pins and apertures can have mutually engaging threads for connecting the segments


108


,


110


together. Alternatively, the connector pins can be press-fit into one or both of their associated apertures


132


,


148


. A guide pin


162


extends through the second aperture


134


of the intermediate ring portion


104


and into the elongate slot


150


of the inner ring portion


106


. As shown most clearly in

FIG. 11

, the connector pin


160


associated with a segment


108


extends into the aperture


148


of a segment


110


A of the inner ring portion


106


, while the guide pin


162


associated with the same segment


108


extends into the elongate slot


150


of an adjacent segment


110


B of the inner ring portion


106


.




The segments


108


,


110


normally remain in a retracted position with the ends of each segment


108


and


110


contacting respective ends of adjacent segments


108


and


110


, due to the biasing member


114


. However, the segments


108


and


110


are expandable radially outwardly by relative movement between the expanders


20


,


22


(FIGS.


1


and


2


), the sealing sleeve


28


, and the outer ring


102


that acts as a wedge against the intermediate and inner rings


104


,


106


to axially shorten and radially expand the sealing sleeve


28


, preferably until the segments


108


,


110


are in contact with the inner surface


24


of the casing


12


. During expansion, adjacent segments


108


in the ring portion


104


and adjacent segments


110


in the ring portion


106


separate to form gaps (not shown) as in the previous embodiments, while the guide pins


162


slide in their associated elongate slots


150


to maintain the segments


108


of the intermediate ring portion


104


offset from the segments


110


of the inner ring portion


106


.




During expansion, the segments


108


,


110


may not move evenly due to differences in applied forces, friction, misalignment of the components, and so on. However, the ends of the elongate slots


150


in the segments


110


serve as end stops to arrest movement of the guide pins


162


during expansion of the segments


108


,


110


to limit the amount of maximum separation between adjacent segments. Thus, when the segments


108


and


110


are fully expanded, the gaps between the segments


108


as well as the gaps between the segments


110


will be substantially uniform. In this manner, the compressive forces of the sealing sleeve


28


will be distributed substantially evenly over the segments.




The inner ring portion


102


, intermediate ring portion


104


, outer ring portion


108


, and pins


160


,


162


are preferably constructed of a thermoplastic material, such as PEEK, but may be formed of other materials such as polyamide, fiber-reinforced composite material, metal, or other suitable material having high temperature resistance and high sheer strength in order to maintain its shape without significant creeping under high temperature and high pressure, as previously described, yet can be easily drilled out or otherwise destroyed when it is necessary to remove the packer assembly


10


.




With reference now to

FIGS. 16-20

, an anti-extrusion ring


200


according to a further embodiment of the invention is illustrated. Although only a single anti-extrusion ring


200


is shown, a further anti-extrusion ring identical in construction to the ring


200


is preferably provided in mirror-reverse orientation so that the rings are positioned between the sealing sleeve


28


(

FIG. 1

) and the upper and lower expanders


20


and


22


, respectively, as previously described with respect to the previous embodiments. The anti-extrusion ring


200


is divided into a plurality of overlapping arcuate segments


201


. Each segment


201


has a first ring portion


202


and a second ring portion


204


that is preferably integrally formed with the first ring portion. As in the previous embodiments, the segments


201


are preferably constructed of a plastic material, such PEEK or other materials such as polyamide, fiber-reinforced composite material, metal, or other suitable material as previously described to thereby facilitate removal of the packer assembly. The segments


201


can be formed by any well-known technique, such as machining or injection molding. As shown, the second ring portion


204


is axially and circumferentially offset from the first ring portion


202


such that the first ring portion


202


of one segment


201


overlaps the second ring portion


204


of an adjacent segment


201


.




Each segment


201


includes arcuate grooves


220


and


222


that, together with the other segments, form continuous grooves that receive annular biasing members (not shown) to hold the segments


201


together in a retracted position, as shown in FIG.


16


. The biasing members are preferably in the form of an elastomeric O-ring, but can alternatively be in the form of a continuous tension spring or the like. Although two arcuate grooves are shown, it will be understood that more or less may be provided.




The first ring portions


202


together form a first wall section


226


that is preferably of a generally hollow frusto-conical shape and a second wall section


228


that extends from the first wall section and is preferably of a generally hollow cylindrical shape. An annular tongue


230


extends from the first wall section


226


. A tapered surface


236


of the first wall section


226


is preferably in contact with either the upper or lower expander


20


,


22


(FIG.


1


), depending on the position of the anti-extrusion ring


200


in the packer assembly


10


. Surfaces


208


and


210


are formed on the first and second ring portions, respectively, and face a direction opposite the tapered surface


236


for contacting the seal


28


(FIG.


1


). The surfaces


208


and


210


are preferably flush where the ring portions on the same segment


201


intersect, as shown in FIG.


17


.




The second ring portions


204


together form an annular wall


240


with a tapered outer surface


242


and an annular surface


244


that abut the first wall section


226


and second wall section


228


, respectively, of a first ring portion


202


of an adjacent segment


201


. An annular depression


246


is formed in the first wall section


226


and is sized for receiving the tongue


230


of the first ring portion


202


of an adjacent segment


201


. Each segment


201


includes an aperture


232


that is formed in the second wall section


228


and an elongate slot


250


that is formed in the annular surface


244


of the wall


240


. Preferably, the aperture


232


extends normal to the second wall section


228


, while the elongate slot


250


extends normal to the annular surface


244


.




A guide pin


260


, preferably constructed of a plastic material, such as PEEK or the like, extends through the aperture


232


of the first ring portion


202


associated with one segment


201


and into the elongate slot


250


of the second ring portion


204


associated with an adjacent segment. It will be understood that the guide pin


260


can be formed of other materials, such as metal.




Due to the biasing member (not shown), the segments


201


normally remain in a retracted position as shown in

FIG. 16

with the ends of each segment


201


contacting respective ends of adjacent segments


201


. As in the previous embodiments, the segments


201


are expandable radially outwardly by relative movement between the expanders


20


,


22


(

FIGS. 1 and 2

) and the sealing sleeve


28


. Although not shown, a ring similar to the ring


102


can be provided between the segments


201


and one or both expanders


20


for wedging against the segments


201


. During expansion, adjacent segments


201


separate to form gaps (not shown) as in the previous embodiments, while the guide pins


260


slide in their associated elongate annular slots


250


preferably until the segments are in contact with the inner surface


24


of the casing


12


. The segments


201


may not move evenly due to differences in applied forces, friction, misalignment of the components, and so on. The ends of the elongate slots


250


provide an end stop for arresting movement of the guide pins


260


during expansion of the segments


201


to limit the amount of maximum separation between adjacent segments. Thus, when the segments


201


are fully expanded, the gaps between the segments


201


will be substantially uniform. In this manner, the compressive forces of the sealing sleeve


28


will be distributed substantially evenly over the segments. Due to the offset and overlapping nature of the first and second ring portions, the second ring portions will be located in the gaps formed between the first ring portions, while the first ring portions will be located in the gaps formed between the second ring portions, to thereby prevent extrusion of the sealing sleeve through the gaps.




In each of the above-described embodiments, the total distance between all gaps of each ring portion in its expanded condition, and especially the inner or first ring portion, is preferably no greater than the distance of the single gap of the prior art metallic anti-extrusion ring. The use of multiple segments facilitates expansion of the anti-extrusion rings and eliminates bending stresses associated with the prior art metallic rings. This feature is especially important, since a solid anti-extrusion ring with a single expansion gap constructed of a plastic material suitable for high temperature and pressure conditions in downhole environments is subject to breakage due to high internal bending stresses generated during expansion. When circumstances dictate removal of the packer assembly, the multi-segmented anti-extrusion rings according to the present invention can be relatively easily drilled out or otherwise destroyed, such as by separation of the individual segments, when compared to the prior art anti-extrusion rings.




It will be understood that the terms inner, outer, upper, lower, as well as other terms and their respective derivatives as may be used throughout the specification refer to relative, rather than absolute positions and/or orientations.




While the invention has been taught with specific reference to the above-described embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and the scope of the invention. For example, it will be understood that the anti-extrusion rings in each of the above embodiments can be constructed with more or less segments than shown. Thus, the described embodiments are to be considered in all respects only as illustrative and not restrictive.



Claims
  • 1. An anti-extrusion ring for a packer assembly having a resilient sealing sleeve, the anti-extrusion ring comprising:first and second ring portions divided into a plurality of discrete arcuate segments for movement between a retracted position wherein each segment is in contact with adjacent segments, and an expanded position wherein gaps are formed between the segments, with at least one of the ring portions being adapted to face the sealing sleeve; an elongate slot associated with each of the segments, the elongate stop having an end stop; and a guide pin extending from each of the segments and into the elongate slot of another segment, such that movement of the segments toward the expanded position causes each guide pin to ride in its respective slot and contact the end stop to thereby arrest further movement of the segments toward the expanded position and control the size of each gap, wherein the first ring portion is circumferentially offset from the second ring portion such that at least one of the first and second ring portions extends across the gaps during movement of the segments toward the expanded position to thereby prevent extrusion of the sealing sleeve through the gaps.
  • 2. An anti-extrusion ring according to claim 1, wherein the first and second ring portions are integrally formed together.
  • 3. An anti-extrusion ring according to claim 2, wherein each segment comprises:an elongate slot associated with one of the first and second ring portions, the elongate slot having an end stop; and a guide pin extending from the other of the first and second ring portions and into the elongate slot of an adjacent segment, such that movement of the segments toward the expanded position causes each guide pin to ride in its respective slot and contact the end stop to thereby arrest further movement of the segments toward the expanded position and control the size of each gap.
  • 4. An anti-extrusion ring according to claim 1, wherein one of the first and second ring portions comprises an annular groove and the other of the first and second ring portions comprises an annular tongue that is received in the annular groove.
  • 5. An anti-extrusion ring according to claim 1, and further comprising at least one annular biasing member extending around the segments for holding the segments together.
  • 6. An anti-extrusion ring according to claim 1, wherein the first and second ring portions are constructed of a plastic material.
  • 7. An anti-extrusion ring according to claim 6, wherein the plastic material comprises polyether ether ketone.
  • 8. An anti-extrusion ring for a packer assembly having a resilient sealing sleeve, the anti-extrusion ring comprising:first and second ring portions divided into a plurality of discrete arcuate segments for movement between a retracted position wherein each segment is in contact with adjacent segments, and an expanded position wherein gaps are formed between the segments, with at least one of the ring portions being adapted to face the sealing sleeve, the plurality of discrete arcuate segments comprising a first set of discrete arcuate segments that forms the first ring portion and a second set of discrete arcuate segments that forms the second ring portion, the first and second sets of arcuate segments being circumferentially offset, each arcuate segment of the first set comprises one of a guide pin and a slot and each arcuate segment of the second set comprises the other of the guide pin and the slot, the slot including an end stop, each guide pin extends into the elongate slot of a first offset segment such that movement of the first and second sets of arcuate segments toward the expanded position causes each guide pin to ride in its respective slot and contact the end stop to thereby arrest further movement of the segments toward the expanded position and control the size of each gap; wherein the first ring portion is circumferentially offset from the second ring portion such that at least one of the first and second ring portions extends across the gaps during movement of the segments toward the expanded position to thereby prevent extrusion of the sealing sleeve through the gaps.
  • 9. An anti-extrusion ring according to claim 8, wherein each arcuate segment of one of the first and second sets is securely connected to a second offset segment adjacent the first offset segment of the other of the first and second sets.
  • 10. An anti-extrusion ring according to claim 9, wherein one of the first and second ring portions comprises an annular groove and the other of the first and second ring portions comprises an annular tongue that is received in the annular groove.
  • 11. A downhole packer assembly for use in a well bore, the downhole packer assembly comprising:an elongate mandrel adapted for positioning in the well bore; an expander adapted for sliding movement along the mandrel; a sealing sleeve disposed around the mandrel for engaging the well bore; and at least one anti-extrusion ring disposed between the expander and the sealing sleeve, the at least one anti-extrusion ring comprising: first and second ring portions divided into a plurality of discrete arcuate segments for movement between a retracted position wherein each segment is in contact with adjacent segments, and an expanded position wherein gaps are formed between the segments, with one of the ring portions contacting the sealing sleeve, an elongate slot associated with each of the segments, the elongate slot having an end stop; and a guide pin extending from each of the segments and into the elongate slot of another segment, such that movement of the segments toward the expanded position causes each guide pin to ride in its respective slot and contact the end stop to thereby arrest further movement of the segments toward the expanded position and control the size of each gap, wherein the first ring portion is circumferentially offset from the second ring portion such that at least one of the first and second ring portions extends across the gaps during movement of the segments toward the expanded position to thereby prevent extrusion of the sealing sleeve through the gaps.
  • 12. A downhole packer assembly according to claim 11, wherein the first and second ring portions are integrally formed together.
  • 13. A downhole packer assembly according to claim 12, wherein each segment comprises:an elongate slot associated with one of the first and second ring portions, the elongate slot having an end stop; and a guide pin extending from the other of the first and second ring portions and into the elongate slot of an adjacent segment, such that movement of the segments toward the expanded position causes each guide pin to ride in its respective slot and contact the end stop to thereby arrest further movement of the segments toward the expanded position and control the size of each gap.
  • 14. A downhole packer assembly according to claim 11, wherein one of the first and second ring portions comprises an annular groove and the other of the first and second ring portions comprises an annular tongue that is received in the annular groove.
  • 15. A downhole packer assembly according to claim 11, and further comprising at least one annular biasing member extending around the segments for holding the segments together.
  • 16. A downhole packer assembly according to claim 11, wherein the first and second ring portions are constructed of a plastic material.
  • 17. A downhole packer assembly according to claim 16, wherein the plastic material comprises polyether ether ketone.
  • 18. A downhole packer assembly for use in a well bore, the downhole packer assembly comprising:an elongate mandrel adapted for positioning in the well bore; an expander adapted for sliding movement along the mandrel; a sealing sleeve disposed around the mandrel for engaging the well bore; and at least one anti-extrusion ring disposed between the expander and the sealing sleeve, the at least one anti-extrusion ring comprising: first and second ring portions divided into a plurality of discrete arcuate segments for movement between a retracted position wherein each segment is in contact with adjacent segments, and an expanded position wherein gaps are formed between the segments, with one of the ring portions contacting the sealing sleeve, the plurality of discrete arcuate segments comprises a first set of discrete arcuate segments that forms the first ring portion and a second set of discrete arcuate segments that forms the second ring portion, with the first and second sets of arcuate segments being circumferentially offset, each arcuate segment of the first set comprises one of a guide pin an a slot and each arcuate segment of the second set comprises the other of the guide pin and the slot, the slot including an end stop, and each guide pin extends into the elongate slot of a first offset segment, such that movement of the first and second sets of arcuate segments toward the expanded position causes each guide pin to ride in its respective slot and contact the end stop to thereby arrest further movement of the segments toward the expanded position and control the size of each gap, wherein the first ring portion is circumferentially offset from the second ring portion such that at least one of the first and second ring portions extends across the gaps during movement of the segments toward the expanded position to thereby prevent extrusion of the sealing sleeve through the gaps.
  • 19. A downhole packer assembly according to claim 18, wherein each arcuate segment of one of the first and second sets is securely connected to a second offset segment adjacent the first offset segment of the other of the first and second sets.
  • 20. A downhole packer assembly according to claim 19, wherein one of the first and second ring portions comprises an annular groove and the other of the first and second ring portions comprises an annular tongue that is received in the annular groove.
CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/239,762 filed on Oct. 12, 2000.

US Referenced Citations (14)
Number Name Date Kind
2780294 Loomis Feb 1957 A
3036639 Baker May 1962 A
3038542 Loomis Jun 1962 A
4852394 Goans Aug 1989 A
5103904 Luke et al. Apr 1992 A
5306021 Morvant Apr 1994 A
5443269 Loritz Aug 1995 A
5524905 Thoman et al. Jun 1996 A
5603511 Keyser, Jr. et al. Feb 1997 A
5676384 Culpepper Oct 1997 A
5701959 Hushbeck et al. Dec 1997 A
5879010 Nilkanth et al. Mar 1999 A
5944102 Kilgore et al. Aug 1999 A
6167963 McMahan et al. Jan 2001 B1
Foreign Referenced Citations (1)
Number Date Country
2 337 064 Nov 1999 GB
Provisional Applications (1)
Number Date Country
60/239762 Oct 2000 US