(12) United States Patent
`McKeachnie et a].
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 7,350,582 B2
`Apr. 1, 2008
`
`US007350582B2
`
`(54) WELLBORE TOOL WITH
`DISINTEGRATABLE COMPONENTS AND
`METHOD OF CONTROLLING FLOW
`
`(75) Inventors‘
`
`.
`
`.
`
`hl/fclielsldizne’ Kayak/U2
`1° “6
`c, 5“ me’ ema’
`)’
`(
`UT (US); Scott Williamson, Castle
`Rock, CO (Us); Rocky A- Turley,
`Houston, TX (Us)
`
`(73) Assignee: Weatherford/Lamb, Inc., Houston, TX
`(US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 242 days.
`
`(21) Appl. No.2 11/01s,406
`
`(22) Filed:
`
`Dec. 21, 2004
`
`(65)
`
`Prior Publication Data
`
`US 2006/0131031 A1
`
`Jun. 22, 2006
`
`(51) Int. Cl.
`(2006.01)
`E21B 34/08
`(52) US. Cl. .................... .. 166/373; 166/376; 166/387;
`166/317;166/318;166/194
`(58) Field of Classi?cation Search .............. .. 166/317,
`166/376, 383, 332.4, 318, 134, 152, 105.5,
`166/387, 194, 373, 374
`See application ?le for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`2,238,895 A
`
`4/l94l Gage et al.
`
`2,672,199 A *
`3,497,003 A *
`3,645,331 A
`5,333,684 A *
`5,335,727 A *
`
`3/1954 McKenna ................. .. 166/134
`2/1970 Kisling et a1. ............ .. 166/134
`2/ 1972 Maurer et al.
`166/1055
`8/1994 Walter et al.
`8/1994 Cornette et a1. .......... .. 166/387
`
`5/1995 Van Buskirk etal.
`5,417,285 A
`1/1996 Gano etal.
`5,479,986 A
`3/l997 Owens et 31‘
`5,607,017 A
`5,685,372 A 11/1997 Gano
`5,765,641 A
`6/1998 Shy et al.
`5,941,309 A *
`8/1999 Appleton .................. .. 166/317
`6,189,618 B1
`2/2001 Beeman et al.
`6,220,350 B1
`4/2001 Brothers et a1.
`6,540,033 B1
`4/2003 Sullivan etal.
`6,752,209 B2* 6/2004 Mondelli et al. ......... .. 166/152
`
`OTHER PUBLICATIONS
`
`CA Of?ce Action, Application No. 2,528,694, Dated Apr. 12, 2007.
`
`* cited by examiner
`
`Primary ExamineriRichard E. Chilcot, Jr.
`Assistant ExamineriMattheW J. Smith
`(74) Attorney, Agent, or F irmiPatterson & Sheridan, LLP
`
`(57)
`
`ABSTRACT
`
`The present invention generally provides a pressure isolation
`plug for managing a Wellbore With multiple Zones. The
`pressure isolation plug generally includes a body With a bore
`extending therethrough, a ?rst disintegratable ball sized and
`positioned to restrict upWard ?uid ?oW through the bore,
`Wherein the disintegratable ball disintegrates When exposed
`to Wellbore conditions for a ?rst amount of time. The plug
`also includes a second ball sized and positioned to restrict
`doWnWard ?uid ?oW through the bore.
`
`15 Claims, 5 Drawing Sheets
`
`201
`
`200
`
`MEGCO Ex. 1014
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`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 1 0f 5
`
`US 7,350,582 B2
`
`MEGCO Ex. 1014
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 2 0f 5
`
`US 7,350,582 B2
`
`FIG. 2
`
`206
`
`208
`
`200
`
`/
`
`201
`
`207
`
`203A
`209
`
`204A
`
`205A
`
`202
`
`201
`
`2058
`
`2048
`
`2038
`
`210
`
`212
`
`211
`
`212
`
`MEGCO Ex. 1014
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 3 0f 5
`
`US 7,350,582 B2
`
`201
`
`200
`
`206
`
`FIG. 3
`
`207
`
`203A
`209
`
`204A
`
`205A
`
`202
`
`201
`
`2058
`
`2048
`
`2038
`210
`
`212
`
`211
`
`212
`
`MEGCO Ex. 1014
`
`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 4 0f 5
`
`US 7,350,582 B2
`
`400
`
`406
`
`FIG. 4
`
`MEGCO Ex. 1014
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`

`

`U.S. Patent
`
`Apr. 1, 2008
`
`Sheet 5 0f 5
`
`US 7,350,582 B2
`
`506
`
`509
`
`501
`
`500
`
`FIG. 5
`
`503A
`
`504A
`
`505A
`
`510
`
`502
`
`501
`
`5058
`
`5048
`
`5038
`
`510
`
`MEGCO Ex. 1014
`
`

`

`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
`Embodiments of the present invention are generally
`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 ?lled With cement to
`permanently set the casing in the Wellbore. The casing is
`then perforated to alloW production ?uid 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 ?uid or to manage
`production ?uid ?oW 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 ?oW of ?uid 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 con?gured to sustain pressure from beloW the
`plug. In other Words, bridge plugs are used to prevent the
`upWard ?oW of production ?uid 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 ?uids 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 ?uids 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 ?oW 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 di?ferentials from above While permitting ?oW from
`beloW. HoWever, too much ?oW 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 ?oW 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
`?gured 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 con?gure 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 ?oW. 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
`
`One embodiment of the present invention provides a
`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 ?oW of ?uid
`therethrough in at least one direction, causing the ball to seat
`and block the ?uid, and permitting the ball to disintegrate
`after a predetermined time period, thereby reopening the tool
`to the ?oW of ?uid.
`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 ?rst disintegratable ball to restrict upWard
`?oW and isolate pressure beloW the pressure isolation plug,
`utiliZing a second disintegratable ball to restrict doWnWard
`?oW and isolate pressure above the pressure isolation plug,
`exposing the ?rst disintegratable ball and the second disin
`
`MEGCO Ex. 1014
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`

`

`US 7,350,582 B2
`
`3
`tegratable ball to Wellbore conditions for a ?rst amount of
`time, causing the ?rst disintegratable ball to disintegrate, and
`allowing upward ?oW 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 ?uid
`?oW 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 ?uid ?oW 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 ?uid ?oW
`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 ?rst disintegratable ball siZed and positioned
`to restrict upWard ?uid ?oW through the bore, Wherein the
`disintegratable ball disintegrates When exposed to Wellbore
`conditions for a ?rst amount of time. The apparatus also
`includes a second ball siZed and positioned to restrict
`doWnWard ?uid ?oW 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, brie?y 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.
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`DETAILED DESCRIPTION
`
`The apparatus and methods of the present invention
`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 con?gured to provide such
`functionality for a predetermined amount of time. It should
`be noted that While utiliZing pressure isolation plugs of the
`
`60
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`65
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`4
`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 con?gured 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 con?gured 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 con?gured to function as a bridge plug, produc
`tion ?uid from formation 14 entering the Wellbore 10 from
`the corresponding perforations 15 is restricted from ?oWing
`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 ?oW 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 ?xed 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
`?uid seal to prevent movement of ?uids 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, con?gured as shoWn in
`FIG. 2, is ready to function as a bridge plug and a frac plug.
`UpWard ?oW of ?uid (presumably production ?uid) causes
`the loWer ball 208 to seat in the loWer ball seat 210, Which
`alloWs the plug 200 to restrict upWard ?oW of ?uid and
`isolate pressure from beloW. This alloWs the plug 200 to
`
`MEGCO Ex. 1014
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`

`

`US 7,350,582 B2
`
`5
`provide the functionality of a conventional bridge plug. It
`should be noted that in the absence of upWard ?oW, the loWer
`ball 208 is retained Within the plug 200 by retainer pin 211.
`DoWnWard ?oW of ?uid causes the upper ball 206 to seat in
`the upper ball seat 209, thereby alloWing the plug 200 to
`restrict doWnWard ?oW of ?uid and isolate pressure from
`above; this alloWs the plug to function as a conventional frac
`plug, Which alloWs fracturing ?uid to be directed into the
`formation through the perforations. Stated another Way, the
`upper ball 206 acts as a one-Way check valve alloWing ?uid
`to ?oW upWards and the loWer ball 208 acts as a one-Way
`check valve alloWing ?uid to ?oW 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 ?oW 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 olf and the upWard
`?oW of production ?uid is stopped as the loWer ball 208
`seats in the ball seat 210. Residual pressure remaining above
`the plug 200 can be bled olf at the surface, enabling the frac
`job to begin. DoWnWard ?oW of fracing ?uid ensures that the
`upper ball 206 seats on the upper ball seat 209, thereby
`alloWing the frac ?uid to be directed into the formation
`through corresponding perforations. After a predetermined
`amount of time, and after the frac operations are complete,
`the production ?uid is alloWed to again resume ?oWing
`upWard through the plug 200, toWards the surface. The
`upWard ?oW is facilitated by the disintegration of the loWer
`ball 208 into the surrounding Wellbore ?uid. 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 ?uids. 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 ?oWing 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 su?iciently small particles, i.e.,
`a colloid, that can be removed by the ?uid 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 ?ller. 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 ?uid
`to ?oW to the surfaceithe upWard ?oW of ?uid 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 ?oW of ?uid Would cause the upper ball
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`206 to seat and the plug 200 Would alloW fracturing ?uid 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 ?oW of ?uid 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 inde?nitely (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 ?oW 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 con?gured for sustaining pressure
`from a single direction. In other Words, the plug could be
`con?gured 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 con?gured 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 ?oW path through the
`plug for production ?uid 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 ?oW 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 ?gure 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 dilferences are the number of disintegratable balls
`(these embodiments only have one) and the pro?le 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 ?oW (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 ?uid ?oW and pressure
`above the plug 400. As With FIG. 2, during upWard ?oW, the
`ball 406 is raised olf the seat and is constrained by retainer
`pin 407. While this embodiment keeps the ball 406 secure
`Within the body of the tool, the ?oW area for production ?uid
`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 ?oW area
`for the upWard moving production ?uid, Which yields higher
`?oW capacity than the plug described With reference to FIG.
`
`MEGCO Ex. 1014
`
`

`

`US 7,350,582 B2
`
`7
`4. This con?guration of the plug (shown in FIG. 5) provides
`a larger ?ow area because the ball 506 can be urged upwards
`and away from the ball seat 509 by the upward ?ow of the
`production ?uid. In fact, the ball 506 is carried far enough
`upward so that it no longer affects the upward ?ow of the
`production ?uid. The resulting ?ow 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 ?uid ?ow, 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 ?uid above.
`With reference to FIG. 4, plug 400 comprises a mandrel
`401 with a straight bore 410 that extends therethrough. With
`downward ?ow (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 ?uid ?ow and pressure
`above the plug 400. As with FIG. 2, during upward ?ow, 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 ?ow area for production ?uid
`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 ?ow area
`for the upward moving production ?uid, which yields higher
`?ow capacity than the plug described with reference to FIG.
`4. This con?guration of the plug (shown in FIG. 5) provides
`a larger ?ow area because the ball 506 can be urged upwards
`and away from the ball seat 509 by the upward ?ow of the
`production ?uid. In fact, the ball 506 is carried far enough
`upward so that it no longer affects the upward ?ow of the
`production ?uid. The resulting ?ow 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 ?uid ?ow, 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 ?uid 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 su?icient
`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 ?ow of ?uid therethrough
`in at least one direction;
`
`5
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`causing the ball to seat and block the ?uid;
`permitting the ball to dissolve after a predetermined time
`period, thereby reopening the tool to the ?ow of ?uid;
`and
`providing a second ball seatable in the tool to block the
`?ow of ?uid 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 ?rst soluble ball to restrict upward ?ow and
`isolate pressure below the pressure isolation plug;
`utiliZing a second soluble ball to restrict downward ?ow
`and isolate pressure above the pressure isolation plug;
`exposing the ?rst soluble ball and the second soluble ball
`to wellbore conditions for a ?rst amount of time,
`causing the ?rst soluble ball to dissolve; and
`allowing upward ?ow 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 ?uid ?ow
`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 ?uid ?ow 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 ?rst dissolvable ball siZed and positioned to restrict
`upward ?uid ?ow through the bore, wherein the dis
`solvable ball dissolves when exposed to wellbore con
`ditions for a ?rst amount of time; and
`a second ball siZed and positioned to restrict downward
`?uid ?ow 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 ?xing 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 ?rst disintegratable ball to restrict upward ?ow
`and isolate pressure below the pressure isolation plug;
`utiliZing a second disintegratable ball to restrict down
`war