Ulllted States Patent [19]
`Whiteley et al.
`
`[54] APPARATUS AND METHOD FOR
`STIMULATING MULTIPLE PRODUCTION
`ZONES IN A WELLBORE
`
`Inventors: TI GI Whiteley, Houston; Douglas JI Lehr Woodlands Michael A Martin
`
`Denn’is Atchley goth of Midl'and all (’)f
`Tex.
`
`[73] Assignee: DJ Services Company, Houston, Tex.
`
`[21] Appl. No.1 09/169,910
`
`Oct‘ 12’ 1998
`[22] Filed:
`[51] Int. Cl? .................................................... .. E21B 43/25
`[52] us CL
`166/306. 166/318
`[58] Field of
`166/306 307
`222 ’177 5’
`’
`'
`
`’
`
`’
`
`~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "
`""""""""
`
`US006006838A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,006,838
`Dec. 28, 1999
`
`8/1977 GaZda ................................... .. 166/217
`4,043,392
`8/1992 Facteall et a1- -
`-
`5,135,051
`5,165,438 11/1992 Facteau et a1. .
`5,181,569
`1/1993 McCoy et a1. ..
`
`.
`
`....................... .. Facteau Ct 8.1. 5,462,129 10/1995 136516161. 2 .............................. .. 175/67
`
`
`5,533,571
`7/1996 SuIJaatmadJa et a1. ............... .. 166/222
`
`Primary Examiner—William Neuder
`Assistant Examiner—]0hn Kreck
`Attorney, Agent, or Firm—Arnold White & Durkee
`[57]
`ABSTRACT
`
`An apparatus and method for selectively stimulating a
`plurality of producing Zones of an openhole wellbore in Oil
`and gas Wells in one trip. The assembly includes a plurality
`of modules connected in a tailpipe Wherein the modules can
`be selectively actuated to conduct a matrix acidiZing job and
`near Wellbore erosion job on producing Zones of interest in
`the Wellbore. Each module includes a sleeve shiftable
`betWeen a closed position and a treating position Where a
`plurality of jet passageways are exposed to the central
`
`[56]
`
`References Cited
`
`US. PATENT DOCUMENTS
`
`2,327,051
`
`7/1943 Lyons et a1. .......................... .. 166/222
`
`passageway of the assembly‘
`
`
`
`
`
`5/1961 Sievers ....... .. 2,997,108 3,912,173 10/1975 Robichaux ............................ .. 239/443
`
`29 Claims, 3 Drawing Sheets
`
`

`
`U.S. Patent
`
`Dec. 28, 1999
`
`Sheet 1 of3
`
`6,006,838
`
`FIG
`2
`
`

`
`U.S. Patent
`
`Dec. 28, 1999
`
`Sheet 2 of3
`
`6,006,838
`
`FIG. 5
`
`2
`9
`
`a M \AAAQQXQXAQQXAQ
`
`
`
`. iZ/é (
`
`XAQXAQQA/VYQXQQQQA/Vw
`
`

`
`U.S. Patent
`
`Dec. 28, 1999
`
`Sheet 3 of3
`
`6,006,838
`
`“"1
`
`FIG. 4
`
`4-0
`
`

`
`1
`APPARATUS AND METHOD FOR
`STIMULATING MULTIPLE PRODUCTION
`ZONES IN A WELLBORE
`
`BACKGROUND OF THE INVENTION
`
`This invention relates to an apparatus and method for
`stimulating producing Zones of an openhole Wellbore in oil
`and gas Wells. More particularly, the invention relates to an
`assembly for selectively stimulating a Wellbore Without the
`use of openhole in?atable packers. The assembly is espe
`cially suited to perform a combination of matrix acidiZing
`jobs and near Wellbore erosion jobs at a number of produc
`ing Zones in the Wellbore in a single trip.
`Previously, operators Who Were interested in stimulating
`multiple producing Zones in an openhole Wellbore could
`stimulate the Zones one Zone at a time by using a Workstring
`and an openhole in?atable packer. Such a method and
`assembly required the operator to set an in?atable packer (or
`other similar apparatus) above each Zone of interest to be
`stimulated and then, folloWing the stimulation job, to release
`the packer (or packers) and trip the packer assembly to a neW
`location Where it Would be reset for the next stimulation job.
`This procedure Would be repeated for each desired Zone of
`interest. HoWever, because of the tripping time and the
`dif?culty in setting and maintaining the seal in in?atable
`packers in openhole Wellbores, such a method Was both time
`consuming and relatively unreliable. Furthermore, openhole
`in?atable packers (or other similar devices) are expensive to
`rent or to purchase. As a result of the relative unreliability
`and cost of using openhole in?atable packers, such assem
`blies prove to be uneconomical in marginal ?elds such as
`?elds in the Permian Basin region of West Texas and Eastern
`NeW Mexico.
`The assembly of the present invention does not require an
`in?atable packer and is very economical to build and main
`tain. Thus, an operator can use the present invention for a
`small incremental cost over What it costs to perform an acid
`job and receives the bene?ts of not only a matrix acidiZing
`treatment, but can also enhance the ?oW in the near Wellbore
`region by eroding aWay near Wellbore skin damage. In
`addition, the present invention alloWs an operator to accu
`rately position an assembly in a Wellbore to ensure that the
`producing Zones of interest are stimulated.
`
`SUMMARY OF THE INVENTION
`
`One embodiment of the present invention is directed to an
`assembly for selectively stimulating a plurality of producing
`Zones in an oil and gas Well comprising a tailpipe string, a
`plurality of modules spaced in the tailpipe string at prede
`termined locations, Wherein each module comprises a hous
`ing having a central passageWay therethrough, a plurality of
`jetting passageWays extending radially through the housing,
`and a shifting sleeve slidably mounted Within the housing
`Wherein the shifting sleeve is moveable from a closed
`position over the jet passageWays to an open position
`Whereby the jet passageWays are in communication With the
`central passageWay of the housing and Wherein the shifting
`sleeve includes a ball seat for receiving an actuating ball for
`shifting the shifting sleeve from the closed position to the
`open position. The loWermost module in the assembly is
`adapted to receive an actuating ball and each successive
`module in the assembly is adapted to receive a larger
`actuating ball than the module immediately beloW it. The
`siZe of the ball seat Will differ from module to module With
`the loWermost module having the smallest ball seat and each
`successive module in the assembly Will have a larger ball
`
`10
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`15
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`25
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`45
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`6,006,838
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`2
`seat than the module immediately beloW it. Each of the jet
`passageWays may include a jet noZZle.
`In another embodiment, the housing may include an
`interchangeable noZZle body Wherein the jet passageWays
`extend radially through the noZZle body. The housing may
`further comprise a top sub connected to the upper end of the
`noZZle body and a bottom sub connected to the loWer end of
`the noZZle body.
`Each module may further comprise one or more radially
`extending ?oW ports in the shifting sleeve beneath the ball
`seat Which communicates With one or more ?oW ports in the
`housing When the shifting sleeve is in the open position.
`Another embodiment of the present invention is directed
`to an assembly for selectively stimulating a plurality of
`producing Zones in an oil and gas Well comprising a plurality
`of modules connected in a tailpipe string Wherein each
`module comprises a housing having a central passageWay
`therethrough, one or more jetting passageWays extending
`radially through the housing, and a shiftable sleeve mounted
`in the central passageWay of the module, Wherein the
`shiftable sleeve is moveable from a closed position over the
`jet passageWays to an open position Whereby the jet pas
`sageWays are in communication With the central passageWay
`of the housing, and Wherein the shiftable sleeve is adapted
`to receive an actuating means for shifting the shiftable
`sleeve from the closed position to the open position. The
`actuating means may include balls, darts, bars, plugs or
`similar devices.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`1.) FIG. 1 illustrates a partial cutaWay of an assembly for
`selectively stimulating a plurality of producing Zones in an
`openhole Wellbore.
`2.) FIG. 2 shoWs a partial cutaWay of one embodiment of
`a module used in the assembly shoWn in FIG. 1.
`3.) FIG. 3 illustrates the module of FIG. 2 With the shifting
`sleeve in the open position.
`4.) FIG. 4 shoWs a partial cutaWay of an alternative
`embodiment of a module for use in an assembly for selec
`tively stimulating a plurality of producing Zones in a Well
`bore.
`
`DESCRIPTION OF ILLUSTRATIVE
`EMBODIMENTS
`
`The illustrative embodiments described herein provide an
`apparatus and method for selectively stimulating multiple
`production Zones or intervals Within a subterranean oil or
`gas Well in a single trip. Persons of ordinary skill in the art,
`having the bene?t of the present disclosure, Will recogniZe
`that the teachings of the present disclosure Will ?nd appli
`cation in any number of alternative embodiments employing
`the general teachings of the illustrative embodiments.
`Therefore, the described directstem assembly and method of
`using the same to selectively stimulate producing Zones in a
`Wellbore are meant to be illustrative and not limiting.
`Accordingly, While the present invention is Well-suited for
`use in horiZontal Wellbores, the invention is only illustrated
`in the accompanying draWings in a substantially vertical
`Wellbore. Persons of ordinary skill in the art Will understand
`that terms such as “loWermost” and “uppermost” in terms of
`horiZontal Wellbores are relative indications of the distance
`or depth from the surface location of the Wellbore.
`Referring to FIGS. 1—3, a preferred embodiment of an
`assembly for selectively stimulating producing Zones in a
`subterranean Wellbore Will noW be described. The direct
`
`

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`6,006,838
`
`15
`
`25
`
`3
`stem assembly 1 includes a plurality of modules Which are
`attached to a tailpipe 4 (shown in cutaway to re?ect the
`longitudinal distance betWeen the modules). The assembly
`in FIG. 1 includes modules 5, 10, 15 and 20. Tailpipe 4 is
`suspended from service packer 3 Which is set inside casing
`6, above the openhole Wellbore 2. The service packer may
`be, for example, a compression packer, such as an SD-l or
`MR1220 packer available from B] Services Company. A
`Workstring of tubing, drillpipe or the like extends from
`packer 3 to the surface. The tailpipe string, being suspended
`from packer 3, extends into the openhole beneath the casing
`shoe. In a preferred embodiment, modules 5, 10, 15 and 20
`are spaced in the tailpipe string at predetermined locations
`so that an individual module is adjacent a producing Zone
`desired to be stimulated. The tailpipe string may be com
`prised of tubing, drillpipe or the like and the length of
`tailpipe betWeen adjacent modules Will depend on the dis
`tance betWeen the producing Zones or targets of interest.
`Alternatively, it Will be understood that the packer could be
`reset at different locations in the casing to locate one or more
`modules of the assembly adjacent one or more producing
`Zones or targets of interest. In other Words, the entire
`assembly can be repositioned Within the Wellbore to more
`accurately position some of the modules Without tripping the
`assembly out of the Wellbore.
`As shoWn in FIG. 2, each module comprises a generally
`tubular-shaped housing 21 Which includes a threaded upper
`and loWer end for connecting the module to the tailpipe
`string. Central passageWay 25 extends longitudinally
`through housing 21. Each module includes shifting sleeve
`22 Which is adapted for longitudinal movement along the
`inner Wall of housing 21. Shifting sleeve 22 includes one or
`more radially extending ports 28 Which are arranged about
`the circumference of the sleeve. Housing 21 also includes
`one or more radially extending ports 27 circumferentially
`spaced about the housing. The number of ports 28 in shifting
`sleeve 22 Will correspond to the number of ?oW ports 27 in
`housing 21. Shifting sleeve 22 includes a landing seat or ball
`seat 35. The siZe of ball seat 35 Will differ from module to
`module in the assembly, With the loWermost module 20
`having the smallest ball seat and the uppermost module 5
`having the largest ball seat.
`Housing 21 may include a plurality of noZZle holes 23
`Which extend radially through the Wall of housing 21 for
`receiving interchangeable jet noZZles 24. Jet noZZles 24 may
`be held in noZZle holes 23 by any suitable means such as
`mating threads, snap rings, Welding or the like. Jet noZZles
`may come in a Wide variety of ori?ce siZes. The siZe of the
`noZZle ori?ce may be predetermined to achieve the desired
`?uid hydraulics for a particular acid job. Some of noZZle
`holes may be selectively blanked off to achieve the optimum
`?oW rates and pressure drops across the remaining noZZles.
`In general, the number and siZe of the Working jet noZZles
`Will re?ect the desired kinetic energy to be used in treating
`a given producing Zone.
`Shifting sleeve 22 is initially attached to housing 21 in the
`closed position by one or more shear screWs 30 so that the
`shifting sleeve straddles jet holes 23, jet noZZles 24 and ?uid
`?oW ports 27. Seals 32 seal the annular space betWeen
`shifting sleeve 22 and housing 21. Elastomeric seals 32 may
`be o-ring seals, molded seals or other commonly used
`oil?eld seals. The remaining components of the module may
`be manufactured from common oil?eld materials, including
`various steel alloys.
`As shoWn in FIG. 3, centraliZing coupling 40 may be
`attached to the loWermost end of housing 21. CentraliZing
`coupling 40 not only connects the module to loWer tailpipe
`
`4
`4 but also centraliZes the module and assembly in the
`Wellbore. CentraliZing coupling 40 includes a plurality of
`centraliZing ribs, With adjacent ?uid ?oW passageWays ther
`ebetWeen.
`As shoWn in FIG. 1, an assembly for selectively stimu
`lating a plurality of intervals or targets in a Wellbore includes
`a plurality of modules assembled in a tailpipe string. By
`varying the length of tailpipe betWeen modules, an operator
`can space the individual modules so that a module is
`adjacent each desired producing interval or target to be
`stimulated. The selectivity is provided by varying the siZe of
`the landing seat 35 on shifting sleeve 22. The loWermost
`module 20 Will have the smallest ball seat 35, i.e., the
`smallest internal diameter of any of the modules, for catch
`ing the smallest ball. The next to last module in the assembly
`Will have a slightly larger ball seat 35 and so on until the
`uppermost module, Which Will have the largest ball seat, i.e.,
`the largest internal diameter of any of the modules. Thus, the
`actuating balls for the assembly Will increase in diameter as
`one moves from the loWermost module to the uppermost
`module.
`In operation, the assembly of FIG. 1 is run into the
`Wellbore suspended from packer 3. The packer is set in the
`production casing near the casing shoe at a predetermined
`location. Tailpipe 4 and modules 5, 10, 15 and 20 extend
`beneath the casing shoe into the open hole. The modules are
`spaced apart in the tailpipe string so that each particular
`module Will be adjacent to a producing Zone that the
`operator desires to stimulate. The stimulation treatment
`begins With the loWermost Zone and Works its Way up the
`Wellbore. An appropriate siZed ball is dropped or pumped
`doWn the Workstring and into the assembly until it lands on
`seat 35 of shifting sleeve 22 in the loWermost module 20.
`Pressure is increased inside the Work string and assembly
`until the force acting across the actuating ball and ball seat
`exceeds the shear value for shear screW 30. Once shear
`screW 30 is sheared, shifting sleeve 22 is shifted doWnWard
`to the treating position against shoulder 42 of housing 21. As
`shoWn in FIG. 3, When the shifting sleeve is in the open or
`treating position, jet noZZles 24 are in communication With
`central passageWay 25. Once landed, ball 37 prevents acid
`from passing out the bottom of the assembly. Acid is then
`pumped at a desired rate through jet noZZles 24 to acidiZe
`and erode the Wellbore adjacent the jet noZZles. The kinetic
`energy created by pumping the acid through the jet noZZles
`mechanically erode aWay the near Wellbore formation dam
`age adjacent the noZZles as illustrated in FIG. 3.
`Upon completion of the acid stimulation treatment of the
`loWermost Zone or target, a slightly larger ball is dropped or
`pumped doWn the Workstring into the assembly Where it
`passes through the upper modules and lands on the ball seat
`of module 15. Pressure is again increased inside the Work
`string to shift the shifting sleeve from the closed position to
`the open position so that the jet noZZles of module 15 are
`exposed. Acid is then pumped through the jet noZZles of
`module 15 to acidiZe and erode the Wellbore adjacent the
`module. The ball in module 15 prevents acid from ?oWing
`doWn to module 20.
`The remainder of the Zones of interest or targets are
`selectively acidiZed or treated by dropping or pumping
`successively larger balls into the assembly and repeating the
`above-described sequence. Upon completion of the stimu
`lation treatment of all Zones, the packer can be released from
`the production casing and the assembly can be pulled out of
`the Well.
`The assembly alloWs an operator to selectively stimulate
`a number of producing Zones in a Wellbore in a single trip.
`
`35
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`6,006,838
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`5
`By dropping successively larger actuating balls, an operator
`can shift a sleeve in successive modules and then squeeZe
`and jet a desired volume of hydrochloric acid or other type
`of acid into the producing Zones of the interest. By diverting
`the acid through the noZZles in the modules, the acid Will
`impact the Wellbore at high velocity under squeeZed pres
`sures. The kinetic energy of the acid Will erode aWay the
`Wellbore and thereby create a cavern in addition to penetrat
`ing the formation rock With the acid. The acidiZing and
`Wellbore erosion Will enhance the ability of oil or other
`hydrocarbons to How into the Wellbore at these locations.
`The Wellbore is thus treated both mechanically and chemi
`cally by dissolving materials that are plugging the pores of
`the formation rock, such as ?nes, paraf?ns, or clays or other
`materials that have reduced the porosity and/or permeability
`of the formation. By jetting a large cavern at the face of the
`Wellbore, the resistance to the How of oil or gas into the
`Wellbore is reduced. Although not limited to such
`application, the present invention is Well suited for stimu
`lating a calcareous formation With, for example, hydrochlo
`ric acid.
`An alternative embodiment of a module for use in an
`assembly of the present invention is shoWn in FIG. 4. The
`module has a generally tubular shaped housing 51 compris
`ing top sub 45, noZZle body 42, and bottom sub 44. Central
`passageWay 51 extends longitudinally through the module.
`The upper portion of top sub 45 includes internal threads for
`connecting the module to upper tailpipe 4. Top sub 45
`includes external threads on its loWer end for connecting top
`sub 45 to noZZle body 42. NoZZle body 42 includes internal
`threads for mating With the external threads of top sub 45.
`NoZZle body 42 also includes external threads on its loW
`ermost end for mating With internal threads on the upper end
`of bottom sub 44. Bottom sub 44 includes threads on its
`loWermost end for mating With internal threads on central
`iZing coupling 40. CentraliZing coupling 40 is threadedly
`attached to the loWer tailpipe 4.
`NoZZle body 42 may be further secured to top sub 45 by
`one or more set screWs 52. Similarly, noZZle body 42 may be
`further secured to bottom sub 44 by one or more set screWs
`53. NoZZle body 42 has a plurality of radially extending
`noZZle ports 58 drilled therethrough. The noZZle ports 58
`extend about the circumference of noZZle body 42. The
`number and siZe of noZZle ports 58 may vary from module
`to module depending on the ?uid ?oW characteristics
`required for the stimulation treatment at each desired pro
`ducing Zone. By Way of example, noZZle body 42 may
`include eight noZZle ports ranging in diameter from 1/16 to
`3/16 of an inch spaced approximately 45 degrees apart about
`the circumference of the noZZle body.
`Shifting sleeve 46 is adapted for longitudinal movement
`along the inner Wall of housing 51. Sleeve 46 includes one
`or more radically extending ?oW ports 50. The annular space
`betWeen shifting sleeve 46 and the inner Walls of top sub 45,
`noZZle body 42, and bottom sub 44 is sealed by a plurality
`of seals 54. Sleeve 46 is shifted from a closed position
`straddling noZZle ports 58 to the stimulating position shoWn
`in FIG. 4 by landing an appropriately siZed shifting ball (not
`shoWn) on ball seat 60. Sleeve 46 is initially held in the
`closed position by one or more shear screWs 48. After a
`shifting ball lands on seat 60 (not shoWn), the tubular
`pressure is increased until shear screWs 48 shear alloWing
`shifting sleeve 46 to be longitudinally moved doWnWard to
`the stimulating position. Shoulder 62 may be provided to
`stop the doWnWard movement of sleeve 46. In the stimu
`lating position, How ports 50 are aligned With a correspond
`ing number of How ports 65 in bottom sub 44, as shoWn by
`
`10
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`15
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`the dotted line. How ports 65 extend radially through the
`bottom sub and are spaced, for example, 45 degrees apart
`from shear screWs 48 along the same plane.
`An operator can change the siZe and number of noZZle
`ports in a module by using interchangeable noZZle bodies 42.
`The interchangeable noZZle bodies provide an operator an
`alternative to the use of interchangeable jet noZZles as
`described in the embodiment of FIG. 2. NoZZle body 42 may
`be made of a variety of steel alloys commonly used in the oil
`industry or may be made of high chromium materials or heat
`treated metals to increase the erosion resistance of noZZle
`ports 58. The remaining portions of the module, including
`top sub 45, bottom sub 44 and shifting sleeve 46, can be
`made of a variety of steel alloys commonly used in the oil
`?eld.
`Although different embodiments of a module are illus
`trated in FIGS. 2 and 4, the method of selectively actuating
`the different modules of an assembly can be more readily
`understood by comparing the respective ball seats of the
`modules in these ?gures. As can be seen, the internal
`diameter of ball seat 60 in the module of FIG. 4 is substan
`tially larger than the internal diameter of ball seat 35 in the
`module of FIG. 2. Thus, the actuating ball for seat 35 Will
`easily pass through ball seat 60 and continue through the
`assembly until it lands on seat 35 of the loWer module.
`Therefore, an operator can selectively actuate the modules in
`the assembly from the bottom up by dropping or displacing
`progressively larger actuating balls into the assembly,
`thereby alloWing the operator to selectively stimulate a
`plurality of producing Zones in a single trip.
`Although the embodiments described above are actuated
`by using successively larger balls, it should be readily
`understood that the modules can be actuated by other means.
`For example, the shifting sleeves of the modules could be
`easily adapted to be actuated by dropping or pumping doWn
`the assembly appropriately siZed darts, bars, plugs, or the
`like. Alternatively, each shiftable sleeve may include a
`selective pro?le, such as an Otis “X” or “R” style pro?le,
`and the actuating means for a particular sleeve Would
`include a locking mechanism With a mating pro?le. In such
`an embodiment, the actuating means Would pass through all
`modules except the module that had a shifting sleeve With a
`mating pro?le.
`Other numerous changes in the details of construction and
`arrangement of parts Will be readily apparent to those skilled
`in the art and Which are encompassed Within the spirit of the
`invention and the scope of the appended claims.
`What is claimed is:
`1. An assembly for selectively stimulating a plurality of
`producing Zones in an oil and gas Well comprising:
`a tailpipe string,
`a plurality of modules spaced in the tailpipe string at
`predetermined locations, Wherein each module com
`prises a housing having a central passageWay
`therethrough,
`a plurality of jetting passageWays extending radially
`through each housing, and
`a shifting sleeve slidably mounted Within each housing,
`Wherein the shifting sleeve is moveable from a closed
`position over the jetting passageWays to an open posi
`tion Whereby the jetting passageWays are in commu
`nication With the central passageWay of each housing,
`and Wherein the shifting sleeve includes a ball seat for
`receiving an actuating ball for shifting the shifting
`sleeve from the closed position to the open position.
`2. The assembly of claim 1 Wherein the loWermost
`module is adapted to receive an actuating ball and each
`
`

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`6,006,838
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`7
`successive module in the assembly is adapted to receive a
`larger actuating ball than the module immediately below it.
`3. The assembly of claim 1 Wherein the siZe of the ball
`seat Will differ from module to module, With the loWermost
`module having the smallest ball seat and each successive
`module in the assembly having a larger ball seat than the
`module immediately beloW it.
`4. The assembly of claim 1 Wherein each of the jetting
`passageWays includes a jet noZZle.
`5. The assembly of claim 1 Wherein each housing further
`comprises a noZZle body and Wherein the jetting passage
`Ways extend radially through the noZZle body.
`6. The assembly of claim 5 Wherein each housing further
`comprises a top sub connected to the upper end of the noZZle
`body and a bottom sub connected to the loWer end of the
`noZZle body.
`7. The assembly of claim 1 further comprising one or
`more radially extending ?oW ports in each shiftable sleeve
`beneath the ball seat Which communicates With one or more
`How ports in the housing on Which the shiftable sleeve is
`mounted When the shifting sleeve is in the open position.
`8. An assembly for selectively stimulating a plurality of
`producing Zones in an oil and gas Well comprising:
`a plurality of modules connected in a tailpipe string,
`Wherein each module comprises a housing having
`central passageWay therethrough, one or more jetting
`passageWays extending radially through the housing,
`and a shiftable sleeve mounted in the central passage
`Way of the module, Wherein the shiftable sleeve is
`moveable from a closed position over the jetting pas
`sageWays to an open position Whereby the jetting
`passageWays are in communication With the central
`passageWay of the housing, and Wherein the shiftable
`sleeve is adapted to receive an actuating means for
`shifting the shiftable sleeve from the closed position to
`the open position.
`9. The assembly of claim 8 Wherein the loWermost
`module is adapted to receive an actuating means and each
`successive module in the assembly is adapted to receive a
`larger actuating means than the module immediately beloW
`it.
`
`10. The assembly of claim 8 Wherein the actuating means
`are balls, darts, bars or plugs.
`11. The assembly of claim 8 Wherein each of the jetting
`passageWays includes a jet noZZle.
`12. The assembly of claim 8 Wherein each housing further
`comprises a replaceable noZZle body Wherein the jetting
`passageWays are drilled radially through the noZZle body.
`13. The assembly of claim 8 Wherein each shiftable sleeve
`has a selective pro?le engageable by a mating pro?le on the
`actuating means.
`14. The assembly of claim 1 or claim 8 Wherein each
`module further comprises a centraliZing coupling connected
`to one end of the module.
`15. The assembly of claim 1 or claim 8 Wherein the
`tailpipe string is suspended from a casing packer.
`16. A method of selectively stimulating a plurality of
`producing Zones in an oil and gas Well in a single trip
`comprising:
`(A) positioning an assembly in the Well, the assembly
`comprising a plurality of modules connected in a
`tailpipe string;
`(i) Wherein each module is adjacent a producing Zone
`to be stimulated, each module comprising:
`(a) a housing having a central passageWay extending
`therethrough;
`(b) one or more jetting passageWays extending radi
`ally through the housing; and
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`8
`(c) a shiftable sleeve slidably mounted Within the
`housing, Wherein the shiftable sleeve is adapted to
`receive an actuating ball for shifting the shiftable
`sleeve from a closed position over the jetting
`passageWays to an open position Whereby the
`jetting passageWays are in communication With
`the central passageWay of the housing;
`(B) selectively stimulating each of the producing Zones in
`succession from the loWermost Zone to the uppermost
`Zone from the module adjacent each Zone by succes
`sively moving the shiftable sleeve to the open position
`in each of the modules beginning With the loWermost
`module and ?nishing With the uppermost module by
`using a progressively larger actuating ball for each of
`the successive modules.
`17. The method of claim 16 further comprising suspend
`ing the assembly in an open hole portion of the Wellbore.
`18. The method of claim 16 further comprising suspend
`ing the assembly from a packer and setting the packer inside
`a casing proximate to an open hole portion of the Wellbore.
`19. The method of claim 16 Wherein said selectively
`stimulating step comprises acidiZing one or more of the
`producing Zones.
`20. The method of claim 16 Wherein said selectively
`stimulating step comprises jetting one or more of the pro
`ducing Zones to erode aWay near Wellbore formation dam
`age.
`21. A method of stimulating multiple target Zones Within
`an oil and gas Well in a single trip comprising:
`(a) making up an assembly comprising a plurality of
`modules connected in a tailpipe string Wherein each
`module comprises:
`(i) a housing having a central passageWay extending
`longitudinally therethrough;
`(ii) one or more jetting passageWays extending radially
`through the housing; and
`(iii) a shiftable sleeve mounted for axial movement
`Within the housing, Wherein the shiftable sleeve is
`adapted to be moved by an actuating means from a
`closed position to an open position, Wherein the
`jetting passageWays are sealed from the central pas
`sageWays by the shiftable sleeve in the closed posi
`tion and the jetting passageWays are in communica
`tion With the central passageWay When the shiftable
`sleeve is in the open position;
`(b) positioning the modules in the assembly adjacent the
`target Zones to be stimulated;
`(c) moving the shiftable sleeve in the loWermost module
`to the open position With an actuating means and
`stimulating the target Zone adjacent the module through
`the jetting passageWays of the module;
`(d) moving the shiftable sleeve in the next loWermost
`module in the assembly to the open position With an
`actuating means and stimulating the target Zone adja
`cent the next loWermost module through the jetting
`passageWays in the module;
`(e) repeating step (d) until all target Zones have been
`stimulated.
`22. The method of claim 21 further comprising siZing the
`actuating means of step (d) to have a larger diameter than the
`actuating means of the next loWermost module.
`23. The method of claim 21 further comprising adapting
`each successive module in the assembly to receive a larger
`actuating means than the module immediately beloW it.
`24. The method of claim 22 further comprising suspend
`ing the assembly in an openhole portion of the Wellbore.
`
`

`
`6,006,838
`
`9
`25. The method of claim 24 further comprising suspend
`ing the assembly from a packer and setting the packer inside
`a casing proximate to the openhole portion of the Wellbore.
`26. The method of claim 25 further comprising resetting
`the packer at a different location inside the casing to position
`one or more of the modules adjacent one or more target
`Zones to be stimulated.
`27. The method of claim 21 further comprising acidiZing
`one or more of the target Zones.
`
`10
`28. The method of claim 21 further comprising jetting one
`or more of the target Zones to erode aWay near Wellbore
`formation damage.
`29. The method of claim 28 further comprising jetting one
`or more of the producing Zones through a jet noZZle located
`in each of the jetting passageWays.
`
`*
`
`*
`
`*
`
`*
`
`*
`
`

`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`: 6,006,838
`PATENT NO.
`: December 28, 1999
`DATED
`INVENTOR(S) : Gilmore et al.
`
`It is certi?ed that error appears in the above-identi?ed patent and that said Letters Patent is hereby
`corrected as shown below:
`Title page,
`Item [75] Inventors, Please add the name of Jesse B. Comwell, Santa Rosa, CA
`
`Signed and Sealed this ’
`
`Sixth Day of February, 2001
`
`Arresting Ojj‘icer
`
`Director of Parents and Trademarks
`
`Q. TODD DICKINSON
`
`

`
`UNITED sTATEs PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`PATENT NO.
`
`DATED
`lNVENTORiSi
`
`:
`
`:
`:
`
`6,006,838
`
`December 28, 1999
`T. G. Whiteley, Douglas J. Lehr, Michael A. Martin, and Dennis Atchley
`
`it is certified that error a