United States Patent
`(12)
`(10) Patent No.:
`US 7,350,582 B2
`
`McKeachnie et al.
`(45) Date of Patent:
`Apr. 1, 2008
`
`US007350582B2
`
`(54) WELLBORE TOOL WITH
`DISINTEGRATABLE COMPONENTS AND
`METHOD OF CONTROLLING FLOW
`
`(75)
`
`Inventors: W. John McKeachnie, Vernal, UT
`.
`.
`(US); Michael McKeachnle, Vernal,
`UT (US); Scott Williamson, Castle
`Rock, CO (US); Rocky A- Turleya
`Houston, TX (US)
`
`(73) Assignee: Weatherford/Lamb, Inc., Houston, TX
`(US)
`
`( * ) Notice:
`
`Subject to any disclailnera the tenn of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 242 days.
`
`(21) Appl. No.: 11/018,406
`.
`Flled:
`
`(22)
`
`Dec. 21, 2004
`
`(65)
`
`Prior Publication Data
`US 2006/0131031 A1
`Jun. 22, 2006
`
`(51)
`
`(56)
`
`Int. Cl.
`(2006.01)
`E213 34/08
`(52) US. Cl.
`...................... 166/373;166/376;166/387;
`.
`.
`166/317’ 166/318’ 166/194
`(58) Field of Classification Search ................ 166/317,
`166/376, 383, 332.4, 318, 134, 152, 105.5,
`1 66/387 194 373 374
`1 t
`3h h'St
`’
`f
`t'
`1.
`e or comp e e searc
`1s ory.
`ee app 10a 10n
`References Cited
`U.S. PATENT DOCUMENTS
`
`S
`
`fil
`
`2,672,199 A
`3,497,003 A
`3,645,331 A
`5,333,684 A
`
`5,335,727 A
`5,417,285 A
`5 479 986 A
`5,607,017 A
`5,685,372 A
`5,765,641 A
`5,941,309 A *
`6,189,618 B1
`6,220,350 B1
`6,540,033 B1
`6,752,209 B2 *
`
`3/1954 McKenna ................... 166/134
`2/1970 Kisling et a1.
`.............. 166/134
`2/ 1972 Maurer et a1.
`
`8/1994 Walter et a1.
`
`166/105.5
`
`.....
`
`............ 166/387
`8/1994 Cornette et a1.
`5/1995 Van Busklrk et al.
`1/1996 Gano et a1
`3/1997 Owens et a1.
`11/1997 Gano
`6/1998 Shy et a1.
`8/1999 Appleton .................... 166/317
`2/2001 Beeman et al.
`4/2001 Brothers et a1.
`4/2003 Sullivan et a1.
`6/2004 Mondelli et 31.
`
`........... 166/152
`
`OTHER PUBLICATIONS
`
`CA Office Action, Application No. 2,528,694, Dated Apr. 12, 2007.
`* cited by examiner
`
`cot,
`.
`10 ar
`xamzneri
`rzmar
`P '
`y E
`'
`R' h d E Chil
`Assistant ExamineriMatthew J. Smith
`(74) Attorney, Agent, or FirmiPatterson & Sheridan, LLP
`
`r.
`J
`
`ABSTRACT
`(57)
`,
`1
`,
`11
`'d
`,
`,
`Th
`epresemmemlongenera ypro.“ esapiessurelso anon
`plug for managmg a wellbore w1th mult1ple zones. The
`ressure isolation lu
`enerall
`includes abod withabore
`y.
`p
`.
`p gg
`.
`y
`.
`extendmg therethrough, a first d1s1ntegratable ball Slzed and
`.
`.
`.
`.
`p0s1t10ned to restrict upward flu1d flow through the bore,
`wherein the disintegratable ball disintegrates when exposed
`t0 wellbore conditions for a first amount of time. The plug
`also includes a second ball sized and positioned to restrict
`downward fluid flow through the bore.
`
`2,238,895 A
`
`4/1941 Gage et a1.
`
`15 Claims, 5 Drawing Sheets
`
`
`
`206
`
`
`
`
`
`208
`
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` ,.
`
`
`
`
`
`
`
`
`
`
`
`
`1
`
`‘
`
`203A
`209
`204A
`205A
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 1 of 5
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`US 7,350,582 B2
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`
`______-IIE...E...II5:.EEIIII______
`
`
`
`
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 2 of 5
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`US 7,350,582 B2
`
`201
`
`200
`
`/
`
`FIG. 2
`
`207
`
`203A
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`____=____
`
`gam—
`
`208
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`
`
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 3 of 5
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`US 7,350,582 B2
`
`201
`
`207
`
`FIG. 3
`
`5Ffivmafififiaxmku\\“u“3‘.“
`
`§Q=§:‘@~;m 203A
`\\§§§\§m
`
`
`205B
`
`E___i____:___|_
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 4 of 5
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`US 7,350,582 B2
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`604
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`____a_=__
`
`=2:
`
`.....
`
`FIG. 4
`
`MEGCO EX. 1009
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`MEGCO Ex. 1009
`
`
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 5 of 5
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`US 7,350,582 B2
`
`FIG. 5
`
`ml
`
`
`§§§§§§§\\\\
`
`
`ABB502154010000555555
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`
`

`

`US 7,350,582 B2
`
`1
`WELLBORE TOOL WITH
`DISINTEGRATABLE COMPONENTS AND
`METHOD OF CONTROLLING FLOW
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`invention are generally
`Embodiments of the present
`related to oil and gas drilling. More particularly, embodi-
`ments of the present invention pertain to pressure isolation
`plugs that utilize disintegratable components to provide
`functionality typically offered by frac plugs and bridge
`plugs.
`2. Description of the Related Art
`An oil or gas well includes a wellbore extending into a
`well to some depth below the surface. Typically, the well-
`bore is lined with a string of tubulars, such as casing, to
`strengthen the walls of the borehole. To further reinforce the
`walls of the borehole, the annular area formed between the
`casing and the borehole is typically filled with cement to
`permanently set the casing in the wellbore. The casing is
`then perforated to allow production fluid to enter the well-
`bore from the surrounding formation and be retrieved at the
`surface of the well.
`
`Downhole tools with sealing elements are placed within
`the wellbore to isolate the production fluid or to manage
`production fluid flow into and out of the well. Examples of
`such tools are frac plugs and bridge plugs. Frac plugs (also
`known as fracturing plugs) are pressure isolation plugs that
`are used to sustain pressure due to flow of fluid that is
`pumped down from the surface. As their name implies, frac
`plugs are used to facilitate fracturing jobs. Fracturing, or
`“fracing”,
`involves the application of hydraulic pressure
`from the surface to the reservoir formation to create fractures
`
`through which oil or gas may move to the well bore. Bridge
`plugs are also pressure isolation devices, but unlike frac
`plugs, they are configured to sustain pressure from below the
`plug. In other words, bridge plugs are used to prevent the
`upward flow of production fluid and to shut in the well at the
`plug. Bridge plugs are often run and set in the wellbore to
`isolate a lower zone while an upper section is being tested
`or cemented.
`
`Frac plugs and bridge plugs that are available in the
`marketplace typically comprise components constructed of
`steel, cast iron, aluminum, or other alloyed metals. Addi-
`tionally, frac plugs and bridge plugs include a malleable,
`synthetic element system, which typically includes a com-
`posite or synthetic rubber material which seals off an annu-
`lus within the wellbore to restrict the passage of fluids and
`isolate pressure. When installed,
`the element system is
`compressed, thereby expanding radially outward from the
`tool to sealingly engage a surrounding tubular. Typically, a
`frac plug or bridge plug is placed within the wellbore to
`isolate upper and lower sections of production zones. By
`creating a pressure seal in the wellbore, bridge plugs and
`frac-plugs isolate pressurized fluids or solids. Operators are
`taking advantage of functionality provided by pressure iso-
`lation devices such as frac plugs and bridge plugs to perform
`a variety of operations (e.g., cementation, liner maintenance,
`casing fracs, etc.) on multiple zones in the same wellborei
`such operations require temporary zonal isolation of the
`respective zones.
`For example, for a particular wellbore with multiple (i.e.,
`two or more) zones, operators may desire to perform opera-
`tions that include: fracing the lowest zone; plugging it with
`a bridge plug and then fracing the zone above it; and then
`repeating the previous steps until each remaining zone is
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`fraced and isolated. With regards to frac jobs, it is often
`desirable to flow the frac jobs from all the zones back to the
`surface. This is not possible, however, until the previously
`set bridge plugs are removed. Removal of conventional
`pressure isolation plugs (either retrieving them or milling
`them up) usually requires well intervention services utilizing
`either threaded or continuous tubing, which is time consum-
`ing, costly and adds a potential risk of wellbore damage.
`Certain pressure isolation plugs developed that hold pres-
`sure differentials from above while permitting flow from
`below. However, too much flow from below will damage the
`ball and seat over time and the plug will not hold pressure
`when applied from above.
`There is a need for a pressure isolation device that
`temporarily provides the pressure isolation of a frac plug or
`bridge plug, and then allows unrestricted flow through the
`wellbore. One approach is to use disintegratable materials
`that are water-soluble. As used herein, the term “disintegrat-
`able” does not necessarily refer to a material’s ability to
`disappear. Rather, “disintegratable” generally refers to a
`material’s ability to lose its structural
`integrity. Stated
`another way, a disintegratable material is capable of break-
`ing apart, but it does not need to disappear. It should be noted
`that use of disintegratable materials to provide temporary
`sealing and pressure isolation in wellbores is known in the
`art. For some operations, disintegratable balls constructed of
`a water-soluble composite material are introduced into a
`wellbore comprising previously created perforations. The
`disintegratable balls are used to temporarily plug up the
`perforations so that the formation adjacent to the perfora-
`tions is isolated from effects of the impending operations.
`The material from which the balls are constructed is con-
`
`figured to disintegrate in water at a particular rate. By
`controlling the amount of exposure the balls have to well-
`bore conditions (e.g., water and heat), it is possible to plug
`the perforations in the above manner for a predetermined
`amount of time.
`
`It would be advantageous to configure a pressure isolation
`device or system to utilize these disintegratable materials to
`temporarily provide the pressure isolation of a frac plug or
`bridge plug, and then provide unrestricted flow. This would
`save a considerable amount of time and expense. Therefore,
`there is a need for an isolation device or system that is
`conducive to providing zonal pressure isolation for perform-
`ing operations on a wellbore with multiple production zones.
`There is a further need for the isolation device or system to
`maintain differential pressure from above and below for a
`predetermined amount of time.
`
`SUMMARY OF THE INVENTION
`
`invention provides a
`One embodiment of the present
`method of operating a downhole tool. The method generally
`includes providing the tool having at least one disintegrat-
`able ball seatable in the tool
`to block a flow of fluid
`
`therethrough in at least one direction, causing the ball to seat
`and block the fluid, and permitting the ball to disintegrate
`after a predetermined time period, thereby reopening the tool
`to the flow of fluid.
`
`Another embodiment of the present invention provides a
`method of managing a wellbore with multiple zones. The
`method generally includes providing a pressure isolation
`plug, utilizing a first disintegratable ball to restrict upward
`flow and isolate pressure below the pressure isolation plug,
`utilizing a second disintegratable ball to restrict downward
`flow and isolate pressure above the pressure isolation plug,
`exposing the first disintegratable ball and the second disin-
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`

`

`US 7,350,582 B2
`
`3
`tegratable ball to wellbore conditions for a first amount of
`time, causing the first disintegratable ball to disintegrate, and
`allowing upward flow to resume through the pressure iso-
`lation plug
`Another embodiment of the present invention provides a
`method of managing a wellbore with multiple zones. The
`method generally includes providing a pressure isolation
`plug, utilizing a disintegratable ball to restrict upward fluid
`flow and isolate pressure below the pressure isolation plug,
`exposing the ball to wellbore conditions including water and
`heat, thereby allowing the ball to disintegrate, and allowing
`upward fluid flow to resume through the pressure isolation
`plug.
`Another embodiment of the present invention provides an
`apparatus for managing a wellbore with multiple zones. The
`apparatus generally includes a body with a bore extending
`therethrough, and a disintegratable ball sized to fluid flow
`through the bore, wherein the disintegratable ball disinte-
`grates when exposed to wellbore conditions for a given
`amount of time.
`
`Another embodiment of the present invention provides an
`apparatus for managing a wellbore with multiple zones. The
`apparatus generally includes a body with a bore extending
`therethrough, a first disintegratable ball sized and positioned
`to restrict upward fluid flow through the bore, wherein the
`disintegratable ball disintegrates when exposed to wellbore
`conditions for a first amount of time. The apparatus also
`includes a second ball sized and positioned to restrict
`downward fluid flow through the bore.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`So that the manner in which the above recited features of
`
`the present invention can be understood in detail, a more
`particular description of the invention, briefly summarized
`above, may be had by reference to embodiments, some of
`which are illustrated in the appended drawings. It is to be
`noted, however, that the appended drawings illustrate only
`typical embodiments of this invention and are therefore not
`to be considered limiting of its scope, for the invention may
`admit to other equally effective embodiments.
`FIG. 1 is a cross-sectional view of a wellbore illustrating
`a string of tubulars having a pressure isolation plug in
`accordance with one embodiment of the present invention.
`FIG. 2 is a detailed cross-sectional view of a pressure
`isolation plug in accordance with one embodiment of the
`present invention.
`FIG. 3 is another detailed cross-sectional view of the
`
`pressure isolation plug shown in FIG. 2.
`FIG. 4 is a detailed cross-sectional view of a pressure
`isolation plug in accordance with an alternative embodiment
`of the present invention.
`FIG. 5 is a detailed cross-sectional view of a pressure
`isolation plug in accordance with yet another embodiment of
`the present invention.
`
`DETAILED DESCRIPTION
`
`invention
`The apparatus and methods of the present
`include subsurface pressure isolation plugs for use in well-
`bores. Embodiments of the present invention provide pres-
`sure isolation plugs that utilize disintegratable components
`to provide functionality typically offered by frac plugs and
`bridge plugs. The plugs are configured to provide such
`functionality for a predetermined amount of time. It should
`be noted that while utilizing pressure isolation plugs of the
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`present invention as frac plugs and bridge plugs is described
`herein, they may also be used as other types of pressure
`isolation plugs.
`FIG. 1 is a cross-sectional view of a wellbore 10 illus-
`
`trating a string of tubulars 11 having an pressure isolation
`plug 200 in accordance with one embodiment of the present
`invention. The string of tubulars may be a string of casing or
`production tubing extending into the wellbore from the
`surface. As will be described in detail below, the pressure
`isolation plug 200 may be configured to used as a frac plug,
`bridge plug or both. Accordingly, the pressure isolation plug
`200, also referred to herein as simply “plug” 200, may
`isolate pressure from above, below or both. For instance, as
`seen in FIG. 1, if the plug is configured to function as a frac
`plug,
`it
`isolates pressure from above and facilitates the
`fracing of the formation 12 adjacent to perforations 13. If the
`plug 200 is configured to function as a bridge plug, produc-
`tion fluid from formation 14 entering the wellbore 10 from
`the corresponding perforations 15 is restricted from flowing
`to the surface.
`
`The pressure isolation plug according to embodiments of
`the present invention may be used as frac plugs and bridge
`plugs by utilizing disintegratable components, such as balls,
`used to stop flow through a bore of the plug 200. The balls
`can be constructed of a material that is disintegratable in a
`predetermined amount of time when exposed to particular
`wellbore conditions. The disintegratable components and
`the methods in which they are used are described in more
`detail with reference to FIGS. 2, 3 and 4.
`FIG. 2 is a detailed cross sectional view of a pressure
`isolation plug 200. The plug 200 generally includes a
`mandrel 201, a packing element 202 used to seal an annular
`area between the plug 200 and an inner wall of the tubular
`string 11 therearound (not shown), and one or more slips
`203A and 203B. The packing element 202 is disposed
`between upper and lower retainers 205A and 205B.
`In
`operation, axial forces are applied to the upper slip 203A
`while the mandrel 201 and the lower slip 203B are held in
`a fixed position. As the upper slip 203A moves down in
`relation to the mandrel 201 and lower slip 203B, the packing
`element 202 is actuated and the upper slip 203A and lower
`slip 203B are driven up cones 204A and 204B, respectively.
`The movement of the cones and the slips axially compress
`and radially expand the packing element 202 thereby forcing
`the sealing portion radially outward from the plug 200 to
`contact the inner surface of the tubular string 11. In this
`manner, the compressed packing element 202 provides a
`fluid seal to prevent movement of fluids across the plug 200
`via the annular gap between the plug 200 and the interior of
`the tubular string 11, thereby facilitating pressure isolation.
`Application of the axial forces that are required to set the
`plug 200 in the manner described above may be provided by
`a variety of available setting tools well known in the art. The
`selection of a setting tool may depend on the selected
`conveyance means, such as wireline,
`threaded tubing or
`continuous tubing. For example, if the plug 200 is run into
`position within the wellbore on wireline, a wireline pressure
`setting tool may be used to provide the forces necessary to
`urge the slips over the cones, thereby actuating the packing
`element 202 and setting the plug 200 in place.
`Upon being set in the desired position within the wellbore
`10, a pressure isolation plug 200, configured as shown in
`FIG. 2, is ready to function as a bridge plug and a frac plug.
`Upward flow of fluid (presumably production fluid) causes
`the lower ball 208 to seat in the lower ball seat 210, which
`allows the plug 200 to restrict upward flow of fluid and
`isolate pressure from below. This allows the plug 200 to
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`

`

`US 7,350,582 B2
`
`5
`provide the functionality of a conventional bridge plug. It
`should be noted that in the absence of upward flow, the lower
`ball 208 is retained within the plug 200 by retainer pin 211.
`Downward flow of fluid causes the upper ball 206 to seat in
`the upper ball seat 209, thereby allowing the plug 200 to
`restrict downward flow of fluid and isolate pressure from
`above; this allows the plug to function as a conventional frac
`plug, which allows fracturing fluid to be directed into the
`formation through the perforations. Stated another way, the
`upper ball 206 acts as a one-way check valve allowing fluid
`to flow upwards and the lower ball 208 acts as a one-way
`check valve allowing fluid to flow downwards.
`As described earlier, for some wellbores with multiple
`(i.e., two or more) zones, operators may desire to perform
`operations that include fracing of multiple zones. Exemplary
`operations for setting the plug 200 and proceeding with the
`frac jobs are provided below. First, the plug 200 is run into
`the wellbore via a suitable conveyance member (such as
`wireline, threaded tubing or continuous tubing) and posi-
`tioned in the desired location. In a live well situation, while
`the plug 200 is being lowered into position, upward flow is
`diverted around the plug 200 via ports 212. Next, the plug
`200 is set using a setting tool as described above. Upon
`being set, the annular area between the plug 200 and the
`surrounding tubular string 11 is plugged off and the upward
`flow of production fluid is stopped as the lower ball 208
`seats in the ball seat 210. Residual pressure remaining above
`the plug 200 can be bled off at the surface, enabling the frac
`job to begin. Downward flow of fracing fluid ensures that the
`upper ball 206 seats on the upper ball seat 209, thereby
`allowing the frac fluid to be directed into the formation
`through corresponding perforations. After a predetermined
`amount of time, and after the frac operations are complete,
`the production fluid is allowed to again resume flowing
`upward through the plug 200,
`towards the surface. The
`upward flow is facilitated by the disintegration of the lower
`ball 208 into the surrounding wellbore fluid. The above
`operations can be repeated for each zone that is to be fraced.
`For some embodiments the lower ball 208 is constructed
`
`of a material that is designed to disintegrate when exposed
`to certain wellbore conditions, such as temperature, water
`and heat pressure and solution. The heat may be present due
`to the temperature increase attributed to the natural tem-
`perature gradient of the earth, and the water may already be
`present in the existing wellbore fluids. The disintegration
`process completes in a predetermined time period, which
`may vary from several minutes to several weeks. Essentially
`all of the material will disintegrate and be carried away by
`the water flowing in the wellbore. The temperature of the
`water affects the rate of disintegration. The material need not
`form a solution when it dissolves in the aqueous phase,
`provided it disintegrates into sufficiently small particles, i.e.,
`a colloid, that can be removed by the fluid as it circulates in
`the well. The disintegratable material is preferably a water
`soluble, synthetic polymer composition including a polyvi-
`nyl, alcohol plasticizer and mineral filler. Disintegratable
`material is available from Oil States Industries of Arlington,
`Tex., U.S.A.
`Referring now to FIG. 3, which illustrates the plug 200 of
`FIG. 2 after the lower ball 208 has disintegrated. The upper
`ball 206 remains intact but still allows the production fluid
`to flow to the surfaceithe upward flow of fluid disengages
`the upper ball 206 from the upper ball seat 209. A retainer
`pin 207 is provided to constrain the upward movement of the
`ball 206. Essentially, FIG. 3 illustrates the plug 200 provid-
`ing the functionality of a conventional frac plug. During a
`frac job, downward flow of fluid would cause the upper ball
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`206 to seat and the plug 200 would allow fracturing fluid to
`be directed into the formation above the plug 200 via the
`corresponding perforations.
`The presence of the upper ball 206 ensures that if another
`frac operation is required, downward flow of fluid will again
`seat the upper ball 206 and allow the frac job to commence.
`With regard to the upper ball 206, if it is desired that the ball
`persist indefinitely (i.e., facilitate future frac jobs), the upper
`ball 206 may be constructed of a material that does not
`disintegrate. Such materials are well known in the art.
`However, if the ability to perform future frac jobs using the
`plug 200 is not desired, both the lower ball and the upper ball
`may be constructed of a disintegratable material.
`Accordingly, for some embodiments, the upper ball 206 is
`also constructed of a disintegratable material. There are
`several reasons for providing a disintegratable upper ball
`206, including: it is no longer necessary to have the ability
`to frac the formation above the plug; disintegration of the
`ball yields an increase in the flow capacity through the plug
`200.
`It should be noted that
`if the upper ball 206 is
`disintegratable too, it would have to disintegrate at a differ-
`ent rate from the lower ball 208 in order for the plug 200 to
`provide the functionality described above. The upper and
`lower balls would be constructed of materials that disinte-
`
`grate at different rates.
`While the pressure isolation plug of FIG. 2 has the
`capability to sustain pressure from both directions, other
`embodiments may be configured for sustaining pressure
`from a single direction. In other words, the plug could be
`configured to function as a particular type of plug, such as
`a frac plug or a bridge plug. FIGS. 4 and 5 illustrate
`embodiments of the invention that only function as frac
`plugs. Both embodiments are configured to isolate pressure
`only from above; accordingly, each is provided with only
`one ball. The disintegratable balls included with each
`embodiment may be constructed of a suitable water soluble
`material so that after a predetermined amount of time
`(presumably after the fracing is done), the balls will disin-
`tegrate and provide an unobstructed flow path through the
`plug for production fluid going towards the surface. As
`stated earlier, these types of plugs are advantageous because
`they allow for frac jobs to be performed, but also allow
`unrestricted flow after a predetermined amount of time,
`without the need of additional operations to manipulate or
`remove the plug from the wellbore.
`With regards to the embodiments shown in FIGS. 4 and
`5, the packing element, retainers, cones and slips shown in
`each figure are identical
`in form and function to those
`described with reference to FIG. 2. Therefore, for purposes
`of brevity they are not described again. As can be seen, the
`primary differences are the number of disintegratable balls
`(these embodiments only have one) and the profile of the
`bore of the respective mandrels.
`With reference to FIG. 4, plug 400 comprises a mandrel
`401 with a straight bore 410 that extends therethrough. With
`downward flow (i.e., pressure from above), the frac ball 406
`lands on a seat 409 and isolates the remainder of the
`
`wellbore below the plug 400 from the fluid flow and pressure
`above the plug 400. As with FIG. 2, during upward flow, the
`ball 406 is raised off the seat and is constrained by retainer
`pin 407. While this embodiment keeps the ball 406 secure
`within the body of the tool, the flow area for production fluid
`is limited to the annular area of the bore of the mandrel 401
`minus the cross-sectional area of the ball 406.
`
`The plug 500 illustrated in FIG. 5 provides more flow area
`for the upward moving production fluid, which yields higher
`flow capacity than the plug described with reference to FIG.
`
`MEGCO EX. 1009
`
`MEGCO Ex. 1009
`
`

`

`US 7,350,582 B2
`
`7
`4. This configuration of the plug (shown in FIG. 5) provides
`a larger flow area because the ball 506 can be urged upwards
`and away from the ball seat 509 by the upward flow of the
`production fluid. In fact, the ball 506 is carried far enough
`upward so that it no longer affects the upward flow of the
`production fluid. The resulting flow through the plug 500 is
`equal to the cross-sectional area corresponding to the inter-
`nal diameter of the mandrel 501. As with the previous
`embodiments, when there is downward fluid flow, such as
`during a frac operation, the ball 506 again lands on the ball
`seat 509 and isolates the wellbore below the plug 500 from
`the fracing fluid above.
`With reference to FIG. 4, plug 400 comprises a mandrel
`401 with a straight bore 410 that extends therethrough. With
`downward flow (i.e., pressure from above), the frac ball 406
`lands on a seat 409 and isolates the remainder of the
`
`wellbore below the plug 400 from the fluid flow and pressure
`above the plug 400. As with FIG. 2, during upward flow, the
`ball 406 is raised off the seat and is constrained by retainer
`pin 407. While this embodiment keeps the ball 406 secure
`within the body of the tool, the flow area for production fluid
`is limited to the annular area of the bore of the mandrel 401
`minus the cross-sectional area of the ball 406. As shown in
`
`FIG. 4. the plug 400 generally includes the mandrel 401, a
`packing element 402 used to seal an annular area between
`the plug 400, and an inner wall of the tubular string 11
`therearound (not shown), one or more slips 403A and 403B
`and one or more cones 404A and 404B. The packing element
`402 is disposed between upper and lower retainers 405A and
`405B.
`
`The plug 500 illustrated in FIG. 5 provides more flow area
`for the upward moving production fluid, which yields higher
`flow capacity than the plug described with reference to FIG.
`4. This configuration of the plug (shown in FIG. 5) provides
`a larger flow area because the ball 506 can be urged upwards
`and away from the ball seat 509 by the upward flow of the
`production fluid. In fact, the ball 506 is carried far enough
`upward so that it no longer affects the upward flow of the
`production fluid. The resulting flow through the plug 500 is
`equal to the cross-sectional area corresponding to the inter-
`nal diameter of the mandrel 501. As with the previous
`embodiments, when there is downward fluid flow, such as
`during a frac operation, the ball 506 again lands on the ball
`seat 509 and isolates the wellbore below the plug 500 from
`the fracing fluid above. As shown in FIG. 5, the plug 500
`generally includes the mandrel 501, a bore 510, a packing
`element 502 used to seal an annular area between the plug
`500, and an inner wall of the tubular string 11 therearound
`(not shown), one or more slips 503A and 503B and one or
`more cones 504A and 504B. The packing element 502 is
`disposed between upper and lower retainers 505A and 505B.
`In some embodiments, the disintegratable balls described
`above may be constructed of materials that will disintegrate
`only when exposed to a particular chemical that is pumped
`down from the surface. In other words, wellbore conditions,
`such as the presence of water and heat may not be suflicient
`to invoke the disintegration of the balls.
`While the foregoing is directed to embodiments of the
`present invention, other and further embodiments of the
`invention may be devised without departing from the basic
`scope thereof, and the scope thereof is determined by the
`claims that follow.
`The invention claimed is:
`
`1. A method of operating a downhole tool, comprising:
`providing the tool having at least one dissolvable ball
`seatable in the tool to block a flow of fluid therethrough
`in at least one direction;
`
`5
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`55
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`60
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`8
`causing the ball to seat and block the fluid;
`permitting the ball to dissolve after a predetermined time
`period, thereby reopening the tool to the flow of fluid;
`and
`
`providing a second ball seatable in the tool to block the
`flow of fluid therethrough in a second direction.
`2. The method of claim 1, further comprising providing a
`dissolvable annular ball seat in the tool.
`3. The method of claim 1, wherein the second ball is
`dissolvable.
`
`4. A method of isolating one section of a wellbore from
`another, comprising:
`providing a pressure isolation plug;
`utilizing a first soluble ball to restrict upward flow and
`isolate pressure below the pressure isolation plug;
`utilizing a second soluble ball to restrict downward flow
`and isolate pressure above the pressure isolation plug;
`exposing the first soluble ball and the second soluble ball
`to wellbore conditions for a first amount of time,
`causing the first soluble ball to dissolve; and
`allowing upward flow to resume through the pressure
`isolation plug.
`5. The method of claim 4, the wellbore conditions com-
`prise water and heat.
`6. A method of isolating one section of a wellbore from
`another, comprising:
`providing a pressure isolation plug;
`utilizing a dissolvable ball to restrict upward fluid flow
`and isolate pressure below the pressure isolation plug;
`exposing the ball to wellbore conditions including water
`and heat, thereby allowing the ball to dissolve; and
`allowing upward fluid flow to resume through the pres-
`sure isolation plug.
`7. The method of claim 6, wherein the wellbore conditions
`comprise water and heat.
`8. An apparatus for isolating one section of a wellbore
`from another, comprising:
`a body with a bore extending therethrough;
`a first dissolvable ball sized and positioned to restrict
`upward fluid flow through the bore, wherein the dis-
`solvable ball dissolves when exposed to wellbore con-
`ditions for a first amount of time; and
`a second ball sized and positioned to restrict downward
`fluid flow through the bore.
`9. The apparatus of claim 8, further comprising a dissolv-
`able annular ball seat.
`
`10. An apparatus for use in a wellbore comprising:
`a body; and
`a slip assembly for fixing the body at a predetermined
`location in a wellbore the slip assembly arranged to
`frictionally contact the wellbore walls:
`whereby at least one portion of the slip assembly is made
`of a dissolvable material constructed and arranged to
`lose its
`structural
`integrity after a predetermined
`amount of time.
`
`11. The apparatus of claim 10, wherein the apparatus is a
`packer.
`12. The apparatus of claim 10, wherein the apparatus is a
`bridge plug.
`13. A method of isolating one section of a wellbore from
`another, comprising:
`providing a pressure isolation plug;
`utilizing a first disintegratable ball to restrict upward flow
`and isolate pressure below the pressure isolation plug;
`utilizing a second disintegratable ball to restrict down-
`ward flow and isolate press