`
`1.
`
`A settable downhole tool for temporarily isolating a zone above the tool from a
`
`zone below the tool in a cased well, comprising:
`
`a mandrel;
`
`a first non-elastomeric ring comprised of metal in a retracted preset configuration
`
`located about the mandrel, having an outer perimeter, an inner perimeter, an upperside, a
`
`lowerside, and a preset gap from the outer perimeter to the inner perimeter;
`
`a second non-elastomeric ring comprised of metal
`
`in a retracted preset
`
`configuration located about the mandrel, having an outer perimeter, an inner perimeter,
`
`an upper side, a lower side, and a preset gap from the outer perimeter to the inner
`
`perimeter;
`
`the outer perimeter of the preset first ring has a greater axial width than the inner
`
`perimeter of the preset first ring and the outer perimeter of the preset second ring has a
`
`greater axial width than the inner perimeter of the preset secondring;
`
`the preset first and second rings’ outer perimeters do not obstruct movement of
`
`the tool in the well;
`
`a non-gap portion of the presetfirst ring is adjacent the preset second ring’s gap;
`
`a non-gap portion of the preset second ring is adjacent the preset first ring’s gap;
`
`a first expander located about the mandrel, configured and comprised so setting
`
`the tool in the cased well will move the first expander toward the first ring and expand
`
`the first ring radially outward to press the first ring’s outer perimeter against the casing,
`
`the first ring’s expanded configuration being the first ring’s post-set configuration, and
`
`expanding the first ring radially outward will circumferentially expand the first ring’s
`
`preset gap to a widerfirst ring post-set gap;
`
`a second expanderlocated about the mandrel, configured and comprisedsosetting
`
`the tool in the cased well will move the second expander toward the second ring and
`
`expand the second ring radially outward to press the second ring’s outer perimeteragainst
`
`the casing, the second ring’s expanded configuration being the second ring’s post-set
`
`configuration, and expanding the second ring radially outward will circumferentially
`
`expandthe second ring’s preset gap to a wider second ring post-set gap; and
`
`the tool is configured and comprised soin the tool’s post-set configuration:
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`21144335v.2
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`40
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`the first ring’s post-set gap is adjacent the casing;
`
`the second ring’s post-set gap is adjacent the casing;
`a non-gap portion of the post-set first ring is adjacent the post-set second ring’s
`
`a non-gap portion of the post-set second ring is adjacent the post-set first ring’s
`
`gap,
`
`gap,
`
`the upper side ofthe post-set first ring is adjacent the lower side ofthe post-set
`
`secondring;
`the post-set first ring and the post-set second ring are configured to cooperatively
`seal against axial fluid flow through anyofthe first ring gap, the second ring gap, and
`between the first and second rings and the casing, so the tool isolates a zone above the
`tool from a zone below the tool to permit fracing in the zone abovethe tool in isolation
`
`from the zone belowthetool;
`
`the tool and the rings are configured and comprised to be interventionless,
`namely, the tool and the rings will degrade enough within less than five days after the
`tool
`is immersed in a natural aqueous downhole fluid in the well produced from
`formation flow in the well having a pH less than 7 and hydrocarbons can be produced
`from a zone below where the tool was set in the well, without milling out the tool,
`
`retrieval of the tool from the well, or other intervention on the tool from the surface; and
`
`the tool does not have an elastomeric sealing element for sealing the tool to the casing
`
`whenthetoolis set against the casing.
`the tool and the rings are configured and
`2.
`The tool of claim 1, comprising:
`comprised to be interventionless, namely, the tool and the rings degrade enough within
`less than two days after the tool is immersed in the natural aqueous downhole fluid in the
`well produced from formation flow in the well having a pH less than 7 so hydrocarbons
`can be produced from a zone below where the tool wasset in the well without milling out
`the tool, retrieval of the tool from the well or other intervention on the tool from the
`
`surface.
`
`The tool of claim 1, comprising: the first ring’s preset gap fully separatesthefirst
`3,
`ring, the first ring being a fully split ring, and the second ring’s preset gap fully separates
`the secondring, the second ring being a fully split ring.
`
`21144335v.2
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`4]
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`
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`4,
`
`The tool of claim 1, comprising:
`
`a portionofthe first ring’s inner perimeter is canted relative to the mandrel’s axis;
`
`the first expander has an outer face facing the first ring which outer face is canted
`
`relative to the mandrel’s axis;
`
`the first ring’s canted inner perimeter portion and thefirst expander’s canted outer
`
`face are canted in the same direction relative to the mandrel’s axis;
`
`the first ring andthe first expander are configured and located so movingthe first
`
`expander toward the first ring when setting the tool moves the first expander’s canted
`outer face toward thefirst ring’s canted inner perimeter portion and radially expandsthe
`
`first ring outward against the casing; and
`
`a portion of the second ring’s inner perimeter is canted relative to the mandrel’s
`
`axis;
`
`the second expander has an outer face facing the first ring which outer face is
`
`canted relative to the mandrel’s axis
`
`the second ring’s canted inner perimeter portion and the second expander’s canted
`
`portion are canted in the samedirection relative to the mandrel’s axis; and
`the second ring and the second expander are configured and located so moving
`the first expander towardthefirst ring whensetting the tool moves the second expander’s
`canted outer face against the second ring’s canted inner perimeter portion and radially
`
`expands the second ring outward againstthe casing.
`5.
`The tool of claim 1, comprising: one of the preset rings has a circumferential
`groove onaside and theother ofthe preset rings has a circumferential tongue ona side,
`
`the groove and tongue being adjacent and engaging each other.
`6.
`The tool of claim 1, comprising:
`the first and second rings are comprised
`
`essentially of metal, the metal comprising aluminum or magnesium.
`
`7.
`
`The tool of claim 1, comprising:
`
`the preset first ring has a first end at a first side of the first ring’s preset gap and
`has a second endat a secondsideofthe first ring’s preset gap,the first ring’s first end has
`
`an extended circumferential portion and a retracted circumferential portion, and the first
`ring’s second end hasa reciprocal retracted circumferential portion opposite the first
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`21144335v.2
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`42
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`
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`end’s extended portion and a reciprocal extended circumferential portion opposite the
`
`first end’s retracted portion;
`
`the post-set first ring’s first end extended portion and the post-set first ring’s
`
`second end extended portion circumferentially overlap, and the post-set first ring’s first
`
`end retracted portion and the post-set first ring’s second end retracted portion do not
`
`circumferentially overlap;
`
`the preset second ring hasa first end at a first side of the second ring’s preset gap
`
`and has a second end at a second side of the second ring’s preset gap, the second ring’s
`
`first end has an extended circumferential portion and a retracted circumferential portion,
`
`and the second ring’s second end has a reciprocal retracted circumferential portion
`opposite the first end’s extended portion and a reciprocal extended circumferential
`
`portion opposite the first end’s retracted portion;
`the post-set second ring’s first end extended portion and the post-set ring’s second
`end extended portion circumferentially overlap, and the post-set second ring’s first end
`retracted portion and second endretracted portion do not circumferentially overlap; and
`the post-set first ring and the post-set second ring are configured to cooperatively
`seal against axial fluid flow through any ofthefirst ring gap, the second ring gap, and
`between the first and second rings and the casing, so the tool isolates the zone above the
`
`tool from the zone below the tool to permit fracing in the zone abovethe toolin isolation
`
`from the zone below thetool.
`
`8.
`
`A settable downhole tool for temporarily isolating a zone above the tool from a
`
`zone below thetool in a cased well, comprising:
`
`a mandrel;
`a first non-elastomeric ring comprised of metal in a retracted preset configuration
`located about the mandrel, the first ring having an outer perimeter, an inner perimeter, an
`upper side, and a lowerside,the first ring being configured and comprisedto be radially
`expandable during setting of the tool to a post-set configuration in whichthefirst ring’s
`outer perimeter is pressed against the casing;
`the first ring has a predetermined separable portion, namely: a full separation in
`the first ring from the first ring’s outer perimeter to the first ring’s inner
`perimeter, a separation only part way throughthe first ring between the first ring’s
`
`21144335v.2
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`43
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`
`
`outer perimeter and the first ring’s inner perimeter, or a weakening groove or
`
`frangible portion extending at
`
`least part way between the first ring’s outer
`
`perimeterandthe first ring’s inner perimeter;
`
`a second non-elastomeric ring comprised of metal
`
`in a preset configuration
`
`located about the mandrel, the second ring having an outer perimeter, an inner perimeter,
`
`an upper side, and a lower side, the first ring configured and comprised to be radially
`
`expandable during setting of the tool to a post-set configuration in which the second
`
`ring’s outer perimeter is pressed against the casing;
`
`the second ring has a predetermined separable portion, namely: a full separation
`
`in the second ring from the second ring’s outer perimeter to the second ring’s inner
`
`perimeter, a separation only part way through the second ring between the secondring’s
`
`outer perimeter and the secondring’s inner perimeter, or a weakening groove or frangible
`
`portion extending at least part way between the second ring’s outer perimeter and second
`
`ring’s inner perimeter;
`
`the preset first and second rings’ outer perimeters do not obstruct movement of
`
`the tool in the well;
`
`a non-separable portion ofthe preset first ring is adjacent the preset second ring’s
`
`separable portion;
`
`a non-separable portion of the preset second ring is adjacent thepresetfirst ring’s
`
`separable portion;
`
`a first expander located about the mandrelin a preset position, the tool configured
`
`and comprised so setting the tool will move the first expander toward the first ring and
`
`expandthefirst ring radially outward to press the first ring’s outer perimeter against the
`
`casing;
`
`a second expander located about the mandrel and a preset position,
`
`the tool
`
`configured and comprised so setting the tool will move the second expander toward the
`
`second ring and expandthe first ring radially outward to press the first ring’s outer
`
`perimeter against the casing;
`the first ring is configured and comprised so radial expansionof the first ring
`during setting of the tool will cause the first ring to circumferentially separate or further
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`21144335v.2
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`44
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`separate at the separable portion, the post-set ring’s separation space or further separation
`
`space beinga first ring gap;
`
`the second ring is configured and comprised so radial expansion of the second
`
`ring during setting of the tool will cause the second ring to circumferentially separate or
`
`further separate at the separable portion, the post-set ring’s separation space or further
`
`separation space being a second ring gap;
`
`the tool is configured and comprised and the preset rings’ separable portions are
`
`located relative to each other so radial expansion of the rings by the expanders and
`
`circumferential expansion of the rings at the ring’s gaps produce a post-set tool and rings
`
`configuration, namely:
`
`the first ring’s post-set gap is adjacent the casing;
`
`the second ring’s post-set gap is adjacent the casing;
`
`a non-gap portion of the post-set first ring is adjacent the post-set second ring’s
`
`a non-gap portion of the post-set second ring is adjacent the post-set first ring’s
`
`gap,
`
`gap;
`
`the upper side of the post-set first ring is adjacent the lowerside of the post-set
`
`second ring; and
`
`the post-set first ring and the post-set second ring are configured to cooperatively
`
`seal against axial fluid flow through anyofthe first ring gap,
`
`the second ring gap, and
`
`between the first and second rings and the casing, and the tool isolates the zone above the
`
`tool from the zone below the tool to permit fracing in a zone abovethe tool in isolation
`
`from a zone below thetool.
`
`9.
`
`The tool of claim 8, comprising: the tool does not have an elastomeric sealing
`
`elementfor sealing the tool to the casing whenthetoolis set against the casing.
`
`10.
`
`The tool of claim 8 comprising: the outer perimeter of the preset first ring has a
`
`greater axial width than the inner perimeter of the preset first ring and the outer perimeter
`
`of the preset second ring has a greater axial width than the inner perimeter ofthe preset
`
`secondring.
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`21144335v.2
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`45
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`11.
`
`The tool of claim 8 comprising: the first and second rings are the only rings in the
`
`tool which in the tool’s post-set configuration cooperatively seal the tool to the casing
`
`against axial fluid flow through the casing.
`
`12.
`
`The tool of claim 8, comprising: the metallic post-set first and second rings press
`
`against the inner wall of the casing creating a metal ring to metal casingseal.
`
`13.
`
`The tool of claim 8, comprising: the rings are comprised essentially of metal, the
`
`metal comprising aluminum or magnesium which will degrade in a natural aqueous
`
`downhole fluid from the formation in the well having a pH less than toward 7.
`
`14.
`
`The tool of claim 8, comprising:
`
`the tool and the rings are configured and
`
`comprised to be interventionless, namely, within less than five days after the tool and the
`
`rings are immersed in a natural aqueous downhole fluid in the well produced from
`
`formation flow in the well having a pH less than 7, the tool and the rings degrade enough
`
`so the tool ceases to isolate the zone above the tool from a zone below the tool, and
`
`hydrocarbons can be produced from a zone below where the tool was set in the well
`
`without milling out the tool, retrieval of the tool from the well or other intervention on
`
`the tool from the surface.
`
`15.
`
`The tool of claim 8, comprising:
`
`the tool and the rings are configured and
`
`comprised to be interventionless, namely, within less than two days after the tool and the
`
`rings are immersed in a natural aqueous downhole fluid in the well produced from
`
`formation flow in the well having a pH less than 7, the tool and the rings degrade enough
`
`so the tool ceases to isolate the zone above the tool from a zone below the tool, and
`
`hydrocarbons can be produced from a zone below where the tool was set in the well
`
`without milling out the tool, retrieval of the tool from the well or other intervention on
`
`the tool from the surface.
`
`16.
`
`The tool of claim 8, comprising: the rings’ outer perimeters are malleable enough
`
`to conform to the inner wall of the casing, and provide a more fluid tight seal with the
`
`casing than similarly configured non-malleable steelrings.
`
`17.
`
`The tool of claim 8, comprising: the rings’ outer perimeters are comprised of a
`
`material which is more malleable than the rings’ inner perimeters.
`
`18.
`
`The tool of claim 8, comprising: in the tool’s pre-set configuration, one ofthe first
`
`ring or the second ring has a circumferential groove on a side, and the reciprocal second
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`21144335v.2
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`46
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`ring or first ring has a circumferential tongue on a side adjacent the circumferential
`
`groove, and the groove and tongue are adjacent and engage each other.
`
`19.
`
`The tool of claim 8, comprising: one of the first ring or the second ring has a
`
`radial groove onaside, and the reciprocal secondringor first ring has a radial tongue on
`
`its side is adjacent the radial groove, the groove and tongue are adjacent and engage each
`
`other, and the engaged adjacent tongue and groove facilitate nonalignment of the rings’
`
`separable portions.
`
`20.
`
`The tool of claim 8, comprising: the first ring’s separable portion is linear, and the
`
`second ring’s separable portionis linear.
`
`21.
`
`The tool of claim 8, comprising:
`
`the preset first ring has a first endat a first side of the first ring’s separable portion
`
`and has a second end at a secondside ofthe first ring’s separable portion,the first ring’s
`
`first end and second end are reciprocally nonlinear, the first ring’s first end has an
`
`extended circumferential portion and a retracted circumferential portion, and the first
`
`ring’s second end has a reciprocal retracted circumferential portion opposite the first
`
`end’s extended portion and hasa reciprocal extended circumferential portion opposite the
`
`first end’s retracted portion;
`
`and a first ring’s first end extended portion circumferentially overlaps a first
`
`ring’s second end extendedportion, and
`
`the preset second ring hasafirst endat a first side of the second ring’s separable
`
`portion and has a second endat a secondside of the second ring’s separable portion, the
`
`second ring’s first end and second endare reciprocally nonlinear, the second ring’s first
`
`end has an extended circumferential portion and a retracted circumferential portion, and
`
`the second ring’s second end hasa reciprocal retracted circumferential portion opposite
`
`the first end’s extended portion and a reciprocal extended circumferential portion
`
`opposite the first end’s retracted portion; and a second ring’s first end extended portion
`
`circumferentially overlaps a second ring’s second end extendedportion.
`
`the post-set first ring’s first end extended portion and the post-set first ring’s
`
`second end extended portion circumferentially overlap, and the post-set first ring’s first
`
`end retracted portion and the post-set first ring’s second end retracted portion do not
`
`circumferentially overlap;
`
`21144335v.2
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`47
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`the post-set second ring’s first end extended portion and the post-set ring’s second
`
`end extended portion circumferentially overlap, and the post-set second ring’s first end
`
`retracted portion and second endretracted portion do not circumferentially overlap; and
`
`the post-set first ring and the post-set second ring are configured to cooperatively
`
`seal against axial fluid flow through any ofthe first ring gap, the second ring gap, and
`
`betweenthe first and second rings and the casing, so the tool isolates the zone above the
`
`tool from the zone below the tool to permit fracing in the zone abovethe tool in isolation
`
`from the zone below thetool.
`
`22.
`
`The tool of claim 8, comprising:
`
`the presetfirst ring has:
`
`a first end at a first side of the first ring’s separable portion and a second end at
`
`the other side ofthe first ring’s separable portion;
`
`the
`
`first
`
`end has
`
`an extended circumferential portion and a
`
`retracted
`
`circumferential portion;
`
`the second end hasa reciprocal retracted circumferential portion opposite the first
`
`end’s extended portion and has a reciprocal extended circumferential portion opposite the
`
`first end’s retracted portion;
`
`the post-setfirst ring’s first end extended portion and second end extended portion
`
`circumferentially overlap, and the post-set first ring’s first end retracted portion and
`
`second end retracted portion do not circumferentially overlap;
`
`the preset second ring has:
`
`a first end at a first side of the second ring separable portion and a second endat
`
`the other side of the second ring separable portion;
`
`the first end has an extended portion and a retracted portion, the second end has a
`
`reciprocal retracted portion opposite the first end’s extended portion and a reciprocal
`
`extended portion opposite the first end’s retracted portion;
`
`the post-set second ring’s first end extended portion and second end extended
`
`portion circumferentially overlap, and the post-set second ring’s first end retracted
`
`portion and second endretracted portion do not circumferentially overlap; and
`
`the post-set first ring and the post-set second ring are configured to cooperatively
`
`seal against fluid flow through the first ring gap, through the second ring gap, and
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`21144335v.2
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`48
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`
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`betweenthe first and second rings and the casing, and the tool isolates the zone above the
`
`tool from the zone below the tool to permit fracing in the zone above the toolin isolation
`
`from the zone below the tool.
`
`23.
`
`The tool of claim 8, comprising:
`
`a portion ofthe first ring’s inner perimeter is canted relative to the mandrel’s axis;
`
`the first expander has an outer face facing the first ring canted relative to the
`
`mandrel’s axis;
`
`the first ring’s canted inner perimeter portion and the first expander’s canted face
`
`are canted in the samedirection relative to the mandrel’s axis;
`
`the tool is configured so movingthe first expander toward the first ring moves the
`
`first expander’s canted face toward the first ring’s canted inner perimeter portion and
`
`radially expandsthe first ring away toward the casing; and
`
`a portion of the second ring’s inner perimeter is canted relative to the mandrel’s
`
`axis;
`
`the second expander has an outer face facing the first ring canted relative to the
`
`mandrel’s axis
`
`the second ring’s canted inner perimeter portion and the second expander’s canted
`
`portion are canted in the samedirectionrelative to the mandrel’s axis; and
`
`tool is configured so moving the second expander toward thefirst ring moves the
`second expander’s canted portion against the second ring’s canted inner perimeterportion
`
`and radially expands the second ring toward the casing.
`
`24,
`
`The tool of claim 8, comprising:
`
`the first ring has a flat upper or lowerside;
`the secondringhasa flat upper or lowerside; and
`
`the flat sides are approximately perpendicular to the mandrel and adjacent each
`
`other.
`
`25.
`
`The tool of claim 8, comprising:
`the first ring’s separable portion is a full separation through thefirst ring from the
`
`ring’s outer perimeter throughto the ring’s inner perimeter; and
`the second ring’s separable portion is a full separation through the second ring
`
`from the ring’s outer perimeter throughto the ring’s inner perimeter.
`
`21144335v.2
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`49
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`26.
`
`The tool of claim 8, comprising:
`
`the first ring’s separable portion is a separation only part way through thefirst
`
`ring betweenthe first ring’s outer perimeter and the first ring’s inner perimeter; and
`
`the second ring separable portion is a separation only part way through the second
`
`ring between the second ring’s outer perimeter and the second ring’s inner perimeter.
`
`27.—The tool of claim 8, comprising:
`
`the first ring separable portion is a weakening groove or frangible portion
`extending at least part way between the first ring’s outer perimeter and inner perimeter,
`
`and
`
`the second ring separable portion is a weakening groove or frangible portion
`extending at
`least part way between the second ring’s outer perimeter and inner
`
`perimeter.
`28.
`The tool of claim 8, comprising: the rings are comprised of metallic materials
`
`which are moreelectrically negative than the mandrel and the casing so the rings will be
`
`sacrificial anodesrelative to the mandrel and the casing whenthe toolis in the casing and
`
`immersed in acidic natural downhole fluids, the resulting galvanic corrosion speeding
`
`degradation of the rings and speeding release of the rings from the casing relative to
`similar rings not subject to the galvanic corrosion.
`29.
`The tool of claim 8, comprising: the first and second rings are comprised of
`
`metallic materials with different electrochemical potentials, namely, one ring being an
`
`anode ring which is moreelectrically negative than the other ring, the other ring being a
`cathode ring, so the anode ring will be a sacrificial anode relative to the cathode ring
`whenthe rings are in the casing and immersed in acidic natural downholefluids, so the
`resulting galvanic corrosion will speed degradation of the rings and speed release of the
`rings from the casing relative to similar rings not subject to the anode ring/cathode ring
`
`galvanic corrosion.
`
`30.
`
`The tool of claim 8, comprising:
`the first and second rings each have multiple predetermined separable portions;
`non-separable portionsofthe preset first ring are adjacent the preset second ring’s
`
`multiple separable portions;
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`21144335v.2
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`50
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`non-separable portions of the preset second ring are adjacentthe preset first ring’s
`
`multiple separable portions; and
`
`the rings’ separable portions and non-separable portions are located so in the
`
`tool’s post set configuration:
`non-gap portions of the post-set first ring are adjacent the post-set second ring’s
`
`multiplegaps; and
`non-gap portions of the post-set second ring are adjacent the post-set first ring’s
`
`multiple gaps.
`31.
`The tool of claim 28, comprising: the first ring and the second ring, each hasat
`least three separable portions, each ring’s separable portions being at least thirty degrees
`
`apart.
`
`32.
`
`The tool of claim 8, comprising:
`
`at least one of each rings’ preset separable portions is a first preset separable
`portion with a full separation of 3/32 inches or moreand the tool is configured so thefirst
`separable portions have a post-set gap of at least 1.5 inches.
`33.
`The tool of claim 8, comprisingthefirst ring’s gap and the second ring’s gap each
`has substantially the same tangential angle relative to the mandrel’s axis and each has a
`tangential angle of 45 degrees to 70 degrees relative to the mandrel’s axis.
`34.
`The tool of claim 8, comprising: the first and secondrings are located, configured
`and sized to circumferentially expand at their separable portions responsive to being
`radially expanded by the
`first and second expanders
`respectively,
`each ring’s
`circumferential expansion at each ring’s separable portion or portions causing the rings to
`circumferentially slide against each other during radial expansion of the rings when the
`
`tool is beingset.
`35.
`The tool of claim 32, comprising: an anti-seize agent located between thefirst
`ring and the second ring which anti-seize agent facilitates the rings circumferentially
`sliding against each other during the radial expansion of the rings when thetoolis being
`set relative to similar rings without an anti-seize agent betweentherings.
`36.
`A settable downhole tool for temporarily isolating a zone above the tool from a
`
`zone below the tool in a cased well having a wellbore fluid, the tool comprising:
`
`a mandrel;
`
`21144335v.2
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`51
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`
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`a first split metallic ring located about the mandrel, and a second split metallic
`
`ring located about the mandrel, the first and second rings each having an inner perimeter
`
`and an outer perimeter, and an upperside and a lowerside;
`
`the first ring and the second ring each has a pre-set configuration in which each
`
`ring’s outer perimeter does not obstruct movementof the tool in the well;
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`a first expander located about the mandrel for moving axially on the mandrel and
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`wedgingthefirst ring radially outward toward a post-set configuration when the toolis
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`set in the well, and a second expander located about the mandrel for moving axially on
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`the mandrel and wedging the
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`second ring radially outward toward a_post-set
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`configuration whenthe tool is set in the well;
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`the tool is configured and comprisedsothefirst ring and the second ring each has
`
`a post-set configuration in which:
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`the first and secondrings are radially expanded from their pre-set configurations
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`so the first and second rings’ outer perimeters press against the casing;
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`the first ring has an outer perimeter gap adjacent the casing, the second ring has
`an outer perimeter gap adjacent the casing, the first ring has a non-gap portion adjacent
`the casing and adjacent the second ring’s gap, and the second ring has a non-gapportion
`adjacent the casing and adjacent the first ring’s gap, and the non-gap portionsofthe first
`ring and secondring seal against the casing enough to isolate a zone above the tool from
`a zone below the tool to permit fracing in the zone above the tool in isolation from the
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`zone below the tool; and
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`the rings are configured and comprised to dissolve quickly enough in a natural
`aqueous downholefluid from the formation in the well having a pH less than toward 7 so
`within less than five daysafter the tool is immersed in the well’s wellbore fluid, the rings
`
`dissolve enough so the tool ceases to isolate the upper zone from the lower zone, without
`milling out the tool, retrieval of the too! from the well or other intervention on thetool
`
`from the surface.
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`37.
`
`A settable downhole tool for temporarily isolating a zone above the tool from a
`
`zone below thetool in a cased well, comprising:
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`a mandrel;
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`21144335v.2
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`52
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`
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`a sealing element located about the mandrel for impeding fluid flow between the
`
`tool and the casing, the sealing element comprising a metallic ring;
`
`wherein the ring has a pre-set configuration in which its outer perimeter does not
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`obstruct movementof the tool in the well, and a post-set configuration in which its outer
`
`perimeter seals against the casing;
`
`an expander located about the mandrel, configured and comprised so setting the
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`tool will move the expander toward the ring so the expander will expand the ring toward
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`the casing and against the casing;
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`the metallic ring is malleable enough so uponsetting the tool, the expanded ring
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`against the casing will seal the tool against radial flow of fluid between the sealing
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`element and the casing;
`
`the ring is configured and comprised to dissolve quickly enough in a natural
`
`aqueous downholefluid from the formation in the well having a pH less than toward 7 so
`
`within less than five days after the tool is immersed in the well’s wellbore fluid, the ring
`
`dissolves enoughso thetool ceases to isolate the upper zone from the lower zone, without
`
`milling out the tool, retrieval of the tool from the well or other intervention on the tool
`
`from the surface; and
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`the tool does not have an elastomeric sealing element for sealing the tool to the
`
`casing whenthetoolis set against the casing.
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`38. A settable downhole tool for temporarily isolating a zone above the tool from a zone
`
`below the tool in a cased well, comprising:
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`a mandrel;
`
`a first non-elastomeric ring which will degrade in an aqueous fluid in the well
`
`having a pH less than 7, the first ring being in a retracted preset configuration located
`
`about the mandrel, having an outer perimeter, an inner perimeter, an upper side, a lower
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`side, and a preset gap from the outer perimeter to the inner perimeter;
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`a second non-elastomeric ring which will degrade in an aqueousfluid in the well
`
`having a pH less than 7, the secondring in a retracted preset configuration located about
`
`the mandrel, having an outer perimeter, an inner perimeter, an upper side, a lower side,
`
`and a preset gap from the outer perimeter to the inner perimeter;
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`21144335v.2
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`53
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`
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`the outer perimeter of the preset first ring has a greater axial width than the inner
`perimeter of the preset first ring and the outer perimeter of the preset second ring has a
`greater axial width than the inner perimeterofthe preset secondring;
`the preset first and second rings’ outer perimeters do not obstruct movement of
`
`the tool in the well;
`
`a non-gap portionofthe presetfirst ring is adjacent the preset second ring’s gap;
`a non-gap portion of the preset second ringis adjacentthepresetfirst ring’s gap;
`a first expander located about the mandrel, configured and comprised so setting
`the tool in the cased well will move the first expander toward the first ring and expand
`the first ring radially outward to press the first ring’s outer perimeter against the casing,
`the first ring’s expanded configuration being the first ring’s post-set configuration, and
`expanding the first ring radially outward will circumferentially expand the first ring’s
`preset gap to a wider first ring post-set gap;
`
`a second expander located about the mandrel, configured and comprised sosetting
`the tool in the cased well will move the second expander toward the second ring and
`expand the second ring radially outward to press the second ring’s outer perimeter against
`the casing, the second ring’s expanded configuration being the second ring’s post-set
`configuration, and expanding the second ring radially outward will circumferentially
`expandthe second ring’s preset gap to a wider secondring post-set gap;
`
`a portion ofthe first ring’s inner perimeteris canted relative to the mandrel’s axis;
`
`the first expander has an outer face facingthe first ring which outer face is canted
`
`relative to the mandrel’s axis;
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`the first ring’s canted inner perimete