Ulllted States Patent
`
`[19]
`
`[11] Patent Number:
`
`6,006,838
`
`Whiteley et al.
`
`[45 J Date of Patent:
`
`Dec. 28, 1999
`
`US006006838A
`
`4,043,392
`8/1977 Gazda ................................... .. 166/217
`5,135,051
`8/1992 Facteau etal.
`.
`. 166/104
`5,165,438
`11/1992 Facteau et al.
`137/1
`5,181,569
`1/1993 McCoy et al.
`. 166/317
`ggégfigg 13/£3: gacttsa: ‘it al'
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`55331571
`711996 sis-a§nf;d3;';;';i""
`M1662/22
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`13‘
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`’
`Primary Examiner—William Neuder
`A5515’“”1 EWm1”9V—J0h11 Kfeck
`Attorney, Agent, or Firm—Arnold W'hitc & Durkcc
`
`
`
`[54] APPARATUS AND METHOD FOR
`STIMULATING MULTIPLE pR()1)UCT[()N
`ZONES INAVVELLBORE
`
`[75]
`
`Inventors: T. G. Whiteley, Houston; Douglas J.
`Lear’ Woodlands; Michael A‘ Martin;
`Dennis Atcliley, both of Midland, all of
`T .
`ex
`[73] Assignee: BJ Services Company, Houston, Tex.
`
`[21] Appl. No.: 09/169,910
`
`[57]
`
`ABSTRACT
`
`[22]
`Oct‘ 12’ 1998
`Filed:
`[51]
`Int. Cl.5 .................................................... .. E21B 43/25
`[52] U.s. Cl.
`............................................. 166/306; 166/318
`.
`[58] Field of Search ..................................... 166/306, 307,
`166/318, 319, 222, 177.5
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`7/1943 Lyons et al.
`............................ 166/222
`5/1961 Sievers ........ ..
`166/222
`
`10/1975 Robichaux ............................ .. 239/443
`
`2,327,051
`2,997,108
`3,912,173
`
`An apparatus and method for selectively stimulating a
`1111119111131 01 P1C}d11C111g Z0335 01 311 01113111101‘? We11b01e 111 911
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`o mo u es connec e
`in a ai pipe W erein
`e mo u es can
`be Selectively actuated to Conduct a matrix acidizingjob and
`.
`.
`.
`.
`.
`near Wellbore erosion _]0b 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
`passageway of the assembly’
`
`29 Claims, 3 Drawing Sheets
`
`1
`
`PACKERS 1001
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`PACKERS 1001
`
`1
`
`

`
`U.S. Patent
`
`Dcc.28, 1999
`
`Sheet 1 of3
`
`6,006,838
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`

`
`U.S. Patent
`
`Dcc.28, 1999
`
`Sheet 3 of3
`
`6,006,838
`
` __//////////////In
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` 4-5
`
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`
`6,006,838
`
`1
`APPARATUS AND METHOD FOR
`STIMULATING MULTIPLE PRODUCTION
`ZONES IN A WELLBORE
`
`BACKGROUND OF THE INVENTION
`
`10
`
`15
`
`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 inflatable 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 inflatable packer. Such a method and
`assembly required the operator to set an inflatable 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
`difficulty in setting and maintaining the seal in inflatable
`packers in openhole wellbores, such a method was both time
`consuming and relatively unreliable. Furthermore, openhole
`inflatable packers (or other similar devices) are expensive to
`rent or to purchase. As a result of the relative unreliability
`and cost of using openhole inflatable packers, such assem-
`blies prove to be uneconomical in marginal fields such as
`fields in the Permian Basin region of West Texas and Eastern
`New Mexico.
`
`The assembly of the present invention does not require an
`inflatable packer and is very economical to build and mam-
`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 benefits of not only a matrix acidizing
`treatment, but can also enhance the flow 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
`
`40
`
`45
`
`60
`
`65
`
`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 flow ports in the shifting sleeve beneath the ball
`seat which communicates with one or more flow 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 benefit of the present disclosure, will recognize
`that the teachings of the present disclosure will find 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-
`
`5
`
`

`
`6,006,838
`
`10
`
`15
`
`3
`stem assembly 1 includes a plurality of modules which are
`attached to a tailpipe 4 (shown in cutaway to reflect 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-1 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 corn-
`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 adjaccnt onc 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-shapcd 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 flow 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
`
`4
`4 but also centralizes the module and assembly in the
`wellbore. Centralizing coupling 40 includes a plurality of
`centralizing ribs, with adjacent fluid flow passageways ther-
`ebetween.
`
`As shown in FIG. I, 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.
`
`the assembly of FIG. 1 is run into the
`In operation,
`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 thc tailpipc string so that cach 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
`pumpcd at a desired rate through jct nozzles 24 to acidizc
`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 flowing
`down to module 20.
`
`40
`
`45
`
`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 orifice sizes. The size of the
`nozzle orifice may be predetermined to achieve the desired
`fluid hydraulics for a particular acid job. Some of nozzle
`holes may be selectively blanked off to achieve the optimum
`flow rates and pressure drops across the remaining nozzles.
`In general, the number and size of the working jet nozzles
`will reflect 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 fluid
`flow 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
`oilfield seals. The remaining components of the module may
`be manufactured from common oilfield 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
`
`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.
`
`60
`
`65
`
`The assembly allows an operator to selectively stimulate
`a number of producing zones in a wellbore in a single trip.
`
`6
`
`

`
`6,006,838
`
`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 flow 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 fines, paraflins, 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 flow 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 fluid flow 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/is to
`3/is 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 flow 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, flow ports 50 are aligned with a correspond-
`ing number of flow ports 65 in bottom sub 44, as shown by
`
`10
`
`15
`
`.
`
`,
`
`40
`
`45
`
`60
`
`65
`
`6
`the dotted line. Flow 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
`field.
`
`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 figures. 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 profile, such as an Otis “X” or “R” style profile,
`and the actuating means for a particular sleeve would
`include a locking mechanism with a mating profile. In such
`an embodiment, the actuating means would pass through all
`modules except the module that had a shifting sleeve with a
`mating profile.
`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
`
`7
`
`

`
`6,006,838
`
`10
`
`15
`
`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 flow ports in each shiftable sleeve
`beneath the ball seat which communicates with one or more
`flow 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.
`
`40
`
`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 profile engageable by a mating profile 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:
`the assembly
`(A) positioning an assembly in the well,
`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
`
`45
`
`60
`
`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 finishing 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 ((1) until all target zones l1ave 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.
`
`8
`
`

`
`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 diiferent 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.
`*
`*
`*
`*
`
`*
`
`9
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`

`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`CERTIFICATE OF CORRECTION
`
`PATENT NO.
`DATED
`|NVENTOR(S)
`
`: 6,006,833
`: December 28, 1999
`: Gi|more et al.
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
`corrected as shown below:
`
`Title page,
`Item [75] Inventors, Please add the name of Jesse E. Comwell, Santa Rosa, CA
`
`Signed and Sealed this C
`
`Sixth Day of February, 2001
`
`éflw ‘
`
`Q