United States Patent 1
`Lendermonet al.
`
`4,744,424
`[11] Patent Number:
`[45] Date of Patent: May 17, 1988
`
`[54]
`
`[75]
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`[73]
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`[21]
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`[22]
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`[51]
`[52]
`[58]
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`[56]
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`SHAPED CHARGE PERFORATING
`APPARATUS
`
`4,523,649
`4,598,775
`
`6/1985 Stout oc eescsseeeeeees 175/4.51
`7/1986 Vann et al... 175/4.6
`
`Inventors: Gary M. Lendermon, Missouri City;
`Jack F, Lands, Jr., West Columbia,
`both of Tex.
`Schlumberger Well Services,
`Houston, Tex.
`
`Assignee:
`
`Appl. No.: 898,962
`
`Aug. 21, 1986
`Filed:
`Int, C14 oo. ccecccscssestcssecsssensoeterseeeeens E21B 43/117
`
`OLS. Cl. cccccscsctceseeee
`.. 175/451; 175/4.6
`Field of Search ...........ccscccseeens 175/2, 4.51, 4.6;
`160/55, 55.1
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,036,521
`3,100,443
`4,375,834
`
`571962 Owen ......cececscccccessseecenenenenees 175/4.6
`
`8/1963 Pohoriles...
`. 175/451
`3/1983 Trott .....cccsccscccsesseresrererenes 175/4.51
`
`Primary Examiner—Stephen J. Novosad
`Assistant Examiner—William P. Neuder
`
`[57]
`
`ABSTRACT
`
`In the representative embodiment of the new and im-
`proved perforating apparatus described herein, shaped
`charge cases are provided with matching upper and
`lower supports with parallel abutment surfaces and
`alignment means cooperatively arranged to enable a
`plurality of these charge cases to be stacked together for
`erecting an intertwined assembly of cases. By appropri-
`ately selecting the combined heights of the matching
`supports, adjacent ones of the charge cases can be
`closely spaced one above the other and directed out-
`wardly along selected radial perforating axes at uniform
`angular spacings.
`
`21 Claims, 3 Drawing Sheets
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`US. Patent May 17, 1988
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`US. Patent May 17, 1988
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`Sheet2 of 3
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`US.Patent May 17, 1988
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`1
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`4,744,424
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`SHAPED CHARGE PERFORATING APPARATUS
`
`FIELD OF THE INVENTION
`
`This invention relates to new and improved well bore
`perforating apparatus operatively arranged to be depen-
`dently suspended in a well bore and selectively oper-
`ated for producing multiple perforations in a cased well
`bore. Moreparticularly, this invention involves new
`and improved perforating appartusincludinga plurality
`of uniquely-interfitting shaped
`explosive
`charges
`adapted to be assembled together to provide an opti-
`mum arrangement of the maximum numberofthe larg-
`est possible charges which can beinstalled in a tubular
`carrier of a given diameter.
`BACKGROUND ART
`
`15
`
`The typical enclosed expendable perforators which
`are used for perforating well bores generally utilize an
`elongated tubular housing or so-called “carrier” in
`which a plurality of laterally-directed shaped explosive
`charges are cooperatively mounted at longitudinally
`spaced intervals. Tofire the charges, a length of deto-
`nating cord is disposed within the carrier and coopera-
`tively positioned within detonating proximity of the
`base of each charge and one end ofthe cord is coupled
`to a detonator which is appropriately arranged to be
`selectively actuated from the surface. These enclosed
`carriers are typically fashioned from steel tubing having
`a wall thickness sufficient to withstand the extreme
`pressure conditions ordinarily encountered in most well
`bores. Once the charges and detonating means have
`been mountedin the carrier, suitable end closure mem-
`bers or headsare positioned in the opposite ends of the
`tubular body to block the entrance of well bore fluids
`into the interior of the carrier.
`Thoseskilled in the art will recognize, of course, that
`for an enclosed carrier of a given diameter, significantly
`larger shaped charges can be employed where the
`charges are inserted into one end ofthe carrier rather
`than being installed through lateral ports in the carrier
`wall. Nevertheless, the typical end-loaded carrierstill
`presents several problems. For instance, steps must be
`taken to reduce the interference to the perforating jets
`that takes place as they pass through the wall of the
`carrier. One commontechnique involves mounting the
`charges in the carrier and angularly aligning them so
`that, when they are detonated, the perforating jet pro-
`duced by each charge will pass through a small-diame-
`ter lateral opening in the carrier wall that is plugged by
`a thin closure member. Asan alternative for these lat-
`eral openings and closure members, small-diameter
`countersunk or blind holes can instead be drilled at
`appropriate locations in the outer wall of the carrier
`during its fabrication so as to leave only reduced-thick-
`ness wall portions to be penetrated by the perforating
`jets when the charges are subsequentlyfired.
`Thoseskilled in theart will, of course, appreciate that
`regardless of whether thin closures or reduced-thick-
`ness wall portions are employed, in either case some
`provision must be made for
`installing the shaped
`charges into the carrier in such a manner that each
`shaped chargewill be accurately aligned with its associ-
`ated reduced-thickness wall portion. Heretofore,
`this
`problem has been resolved by simply mounting the
`shaped charges intended for a given carrier on an elon-
`gated tubular support that is cooperatively arranged to
`be inserted longitudinally into the carrier and posi-
`
`40
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`45
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`65
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`2
`tioned as needed for aligning the several charges with
`their respective reduced-thickness wall portions. Typi-
`cally these elongated supports have been fabricated by
`cutting a series of longitudinally spaced lateral openings
`in the opposingside walls of elongated metalorplastic
`tubes which have either a square or circular cross-sec-
`tion of suitable dimensionsto snugly fit the internal bore
`of the carrier body.
`These elongated tubular supports have, of course,
`been generally satisfactory for use in end-loaded carri-
`ers where it
`is considered adequate to mount
`the
`chargesin the carrier at such typical longitudinal spac-
`ings as two or four shaped chargesperfoot of length of
`the carrier. With these spacings, the forward and rear
`portions of the charge cases are retained in the opposed
`openings in the charge supports and thereis sufficient
`material remaining in a given support tube to keep the
`charges from being misaligned by rough handling or by
`impact forces on the carrier as it is being lowered into a
`well bore. As described in U.S. Pat. No. 3,773,119, for
`example, support tubes such as these have been success-
`fully used heretofore by forming the supports from
`tubes of heavy cardboardorfiberglass having sufficient
`strength for supporting the charge cases during perfo-
`rating operations as well as by using square tubes that
`can beeasily flattened where necessaryto also resolve a
`shipping or storage problem.
`In the past few years it has been found that in some
`situations it is necessary to significantly increase the
`numberof perforations per foot in a given perforated
`interval of a well bore. In particular, recent develop-
`ments in conducting gravelpack operations have made
`it advantageousto putat least ten or twelve perforations
`per foot in each well bore interval that is to be gravel
`packed. Thoseskilled in the art will realize, of course,
`that there is a practical limit to the number of shaped
`charges of a given size that can be mounted in a given
`length of a typical support tube. For instance, if the
`overall length of the charges is greater than the radius
`of the internal bore of the carrier, only one shaped
`charge can be mounted in any given transverse plane.
`Conversely, if more than one chargeis to be mounted in
`the same transverse plane, the overall length of each
`charge is limited to something less than the internal
`radius of the carrier and the overall performance of
`these charges will be correspondingly reduced. In any
`case, it will be recognized that if a typical support tube
`is to be arranged to carry more than four shaped
`chargesperfoot, the overall strength ofthe tube will be
`greatly reduced so that it will be difficult to protect
`these tubes during their shipment and storage. It has
`also been found that these weaker tubes can beeasily
`damagedby rough handling oncethe perforator carrier
`is loaded and is ready for operation.
`Other proposals which have been madeforinstalling
`a large number of shaped charges in an end-loaded
`carrier involve the use of three or four shaped charges
`which are loaded in a unitary container and respectively
`aligned to be fired along a separate perforating axis that
`is angularly displaced from the perforating axes of the
`other charges in the same container. A numberofthese
`charge clusers are then stacked in a typical end-loaded
`carrier and cooperatively associated with a detonating
`cord extending along the central axis of the stacked
`containers.
`.
`Thoseskilled in the art will, of course, recognize that
`in addition to the problems mentioned above regarding
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`shaped charges that are positioned in a commontrans-
`verse plane, there is also a significant reduction in the
`overall performance of the charges by virtue of the
`charges being stacked in close proximity to one another.
`It should also be noted that it is time consuming to
`install the detonating cord through a large number of
`charge containers as they are stacked in a carrier; and
`thatit is even more difficult to reload the carrier should
`it later become necessary either to increase or decrease
`the number of charges in the carrier or to change the
`longitudinal spacing between the charges.
`OBJECTS OF THE INVENTION
`
`5
`
`4
`To firmly secure the assembled charge cases in their
`respective positions in this unique assembly, the align-
`ment means on each charge case include matching
`upper and lower alignment guides that are respectively
`located on opposite sides of each charge case and coop-
`eratively arranged so that the upper guide on oneside of
`the first charge case in one series of the cases will be
`operatively associated with the lower alignment guide
`on the otherside of the secondcase in that series and the
`upper guide on the opposite side of that second case will
`also be operatively associated with the lower alignment
`guide on the one side of the third case in that same
`series. In this manner, as the several charge cases are
`cooperatively stacked together and successively aligned
`with the adjacent charge cases, the several charge cases
`in this unique stacked assembly will be firmly retained
`in their respective location in the intertwined stacks so
`that once the entire assembly is completed, it can be
`inserted as a unit into one end of an elongated tubular
`carrier and positioned therein as needed for angularly
`aligning each of the shaped charges with their respec-
`tive reduced-thickness wail portion or closure member
`in the carrier wall.
`
`Accordingly,it is an object of the present invention
`to provide new and improved perforating apparatus
`having shaped explosive charges which can be quickly
`and reliably installed as a group in a typical end-loaded
`carrier and be firmly secured in a precise alignment
`with their respective port-closure members of reduced-
`thickness wall portion in the carrier.
`SUMMARY OF THE INVENTION
`
`20
`
`This and other objects of the present invention are
`attained by cooperatively arranging support means and
`alignment means on each ofa plurality of essentially
`identically shaped charge cases respectively containing
`a shaped explosive charge that is adapted to develop a
`perforating jet along the central longitudinal axis of the
`charge case. To enable these several charge cases to be
`fitted together to form a unique assemblythatis particu-
`larly adapted to be installed into an elongated end-
`loaded carrier, the support means on each ofthe charge
`cases are cooperatively arranged to provide matching
`upwardly-facing and downwardly-facing abutment sur-
`faces that are respectively lying in parallel transverse
`planes spatially disposed above and below the central
`axis of the charge case so that by engaging the upper
`abutmentsurface on oneside ofa first charge case with
`the lower abutmentsurface on the other side of a second
`case as well as engaging the upper abutment surface on
`the opposite side of the second case with the lower
`abutment surface on one side of a third case and con-
`tinuing in this manner, a first group of these serially-
`arranged charge cases will cooperatively define a first
`stacked structure that has the central axis of each case in
`the stack respectively lying in a successively higher
`transverse plane and angularly oriented in oneofat least
`three selected lateral directions.
`By forming each of the cases with a cylindrical for-
`ward portion and a frustoconical rearward portion and
`interfitting the rearward portions of the charges cases
`together, this first group of charge cases can be assem-
`bled with at least second and third groupsofserially-
`arranged identical charge cases whereby the upper
`abutmentsurface on oneside of the first charge case in
`the second group is engaged with the lower abutment
`surface on the otherwise-unsupported one side of the
`second chargecasein thefirst group of chargecases. In
`a similar fashion, the upper abutment surface on one
`side ofthe first charge case in the third group is engaged
`with the lower abutment surface on the otherwise-
`unsupported one side of the second charge case in the
`second group. To complete this intertwined assembly,
`the lower abutment on oneside of thefirst charge case
`in the third group is supported by the upper abutment
`on the other side of the first charge case in the first
`group.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Thenovel featuresof the present invention are set out
`with particularity in the appended claims. The inven-
`tion along with further objects and advantages thereof
`may, therefore, be best understood by way ofthe fol-
`lowing description of exemplary apparatus employing
`the principles of the present invention as illustrated in
`the accompanying drawings in which:
`FIG.1 is an elevational view, partially in cross-sec-
`tion, showing a typical stacked assembly of a plurality
`of shaped charges respectively disposed in a preferred
`embodimentof interlocking charge containers arranged
`in accordance with the principles of the present inven-
`tion;
`FIG.2 is a plan view taken along the lines “2—2”of
`FIG.1 and depicts a preferred embodiment of an upper
`base memberthatis included with the stacked assembly
`of the shaped charges shownin that drawing;
`FIG.3 is a plan view taken along the lines “3—-3”in
`FIG. 1 which depicts a preferred embodiment of a
`lower base memberthat is included with the stacked
`assembly of the shaped charges shown in the drawing;
`FIG.4 is a plan view taken alongthe lines “4—4”in
`FIG.1 and depicts the uppermost shaped chargesin the
`new and improved intertwined assembly shownin that
`drawing; and
`FIGS. 5, 6 and 7 respectively illustrate the front ele-
`vation, the side elevation and the rear elevation of the
`new and improved shaped charge cases arranged in
`accordance with the principles of the invention.
`DETAILED DESCRIPTION OF A PREFERRED
`EMBODIMENT
`
`40
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`Turning now to FIG.1, an elevational view is shown
`of perforating apparatus 10 cooperatively arranged in
`accordance with the principles of the present invention
`and including a plurality of essentially-identical shaped
`explosive charges, as shown generally at 11, which have
`been assembled together into a unique intertwined as-
`sembly 12 of the charges that is adapted to be installed
`into one end of an elongated end-loaded carrier, as at
`13, that is then closed at its upper and lower ends by
`upper and lower head members 14 and 15 ofa typical
`design.
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`25
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`5
`6
`Asis common,the new and improved apparatus10 is
`rearward portion which receives a suitable primer ex-
`appropriately arranged to be dependently suspended at
`plosive and a cylindrical forward portion which re-
`a selected depth in a well bore and thereafterselectively
`ceives a compressed explosive with a forwardly-open-
`operated for perforating the casing and cement sheath
`ing cavity in which a hollow frustoconical metal liner
`at the selected depth. Thoseskilled in the art will appre-
`28 is cooperatively arranged to develop a perforating
`ciate that in the practice of the present invention,it is
`jet along the central axis of the case. It will, of course,
`immaterial whether the carrier 13 is cooperatively ar-
`be appreciated that the particular design details of the
`ranged for connection to the lower end ofa suitable
`cases 27 and the explosive componentsof the charges 11
`suspension cable with electrical conductors such as the
`are outside of the scope of the present invention. In any
`perforator depicted, for example,
`in U.S. Pat. No.
`event, the explosive components of the shaped charges
`3,773,119 or whether the carrier is alternatively ar-
`11 can be selected to have the performancecharacteris-
`ranged to be connected to the lower end of a tubing
`tics believed necessary for a given perforating opera-
`tion.
`string such as the perforator shown in U.S. Pat. No.
`4,509,604. In either situation, as explained in moredetail
`Regardless of the particular operating characteristics
`in these aforementioned patents (both of which are
`required for a given set of the shaped charges 11, the
`incorporated herein by reference), once thecarrier 13is
`inner charge cases 27 are respectively mounted within
`positioned adjacent to a given formation interval of
`complementally-shaped hollow containers or outer
`interest, it is apparent to one with only ordinary skill in
`cases, as at 29, which, in the illustrated embodiment of
`the art how to arrange the new and improvedperforat-
`the present invention, are preferably made fromasuit-
`20
`ing apparatus 10 so it can be selectively actuated when-
`able high-strength thermoplastic material that enables
`ever desired.
`the cases to be economically fabricated by means such
`It should be recognized that when the intertwined
`as an appropriate injection molding process. Although
`assembly 12 is installed in the carrier 13, each of the
`it has been found that a preferred material for these
`shaped charges 11 must be accurately aligned with its
`outer containers 29 as well as the upper and lower base
`respectively-associated blind bore in the outer wall of
`supports 18 and 19 is a glass-filled nylon such as pres-
`the carrier that is terminated by a reduced-thickness
`ently marketed by the DuPont Corporation under the
`wall portion as shown,for example,at 16 and 17 in FIG.
`trademarkof “Zytel’, those skilled in the art will recog-
`4. Accordingly,as illustrated in FIG.1, the intertwined
`nize that other plastics with similar high-temperature
`assembly 12 is arranged as a unitary stack of the shaped
`and high-strength characteristics may also be used for
`charges 11 which are intercoupled together with the
`fabricating the outer cases 29 as well as the base sup-
`uppermost and lowermost charges in the stack coupled
`ports 18 and 19.
`to upper and lower base supports 18 and 19. To cor-
`Asillustrated in FIG. 1, it will be appreciated that by
`rectly position the charges 11 longitudinally with re-
`virtue of the unique configuration of the several outer
`spect to the carrier 13, the upper face of the lower head
`cases, as at 29, the intertwined assembly 12 is comprised
`ofa first stacked structure ofserially-arranged cases, as
`15 is arranged to locate the lower base support 19 at the
`appropriate elevation within the carrier needed to place
`shown at Al, A2... An, a second stacked structure
`the central perforating axes, as at 20, of the charges in
`formed with other serially-arranged cases, as shown at
`Bi, B2... Bn, as well as a third stacked structureofstill
`the same transverse plane as the longitudinal axis of
`their respective blind bores, as at 16, whenever the
`another group of serially-arranged charge cases, as
`shown at C1... Cn—1 and Cn.
`intertwined assembly 12 is installed in the carrier. The
`lower end of the intertwined assembly 12 is also re-
`As previously mentioned, the intertwined assembly
`tained in the proper angular alignment with respect to
`12 further includes the upper and lower base supports
`the carrier 13 by means such as a Ing or outwardly-
`18 and 19 which are respectively coupled to the upper
`projecting finger 21 formed on oneside of the lower
`and lowerendsofthe interlocking stacked structures A,
`base support 19 to be biased outwardly into a longitudi-
`B and C to give additional strength to the entire assem-
`nal groove 22 in the wall of the lower portion of the
`bly. It should be recognized from FIG.1 that the cases
`carrier. The upper base support 18 is slightly larger in
`29 in a given group ofserially-arranged cases are also
`diameter than the lower base support 19 so as to define
`respectively angularly displaced by an angle of 45-
`an enlarged-diameter shoulder 23 that will engage an
`degreesin relation to the other outer cases immediately
`upwardly-facing shoulder 24 near the upper end of the
`above and below that case. As a result of this angular
`carrier 13 when the lowerbase support is resting on the
`displacement, the frustoconical rearward portion of an
`lower head member 15. The upper head 14for the car-
`outer case, such as at B1 in the stacked structure B, can
`tier 13 is cooperatively arranged to engage the upper
`be readily disposed within the interstitial spaces defined
`face of the upper base support 18 so that oncethe perfo-
`between two adjacent cases such as A1 and A2in the
`rating apparatus has been completely assembled, the
`stacked structure A. Similarly, the frustoconical rear-
`intertwined assembly 12 is secured against moving lon-
`ward portions of the outer cases, such as at C1, can also
`gitudinally in relation to the carrier. The upper end of
`be cooperatively disposed within the irregular intersti-
`the intertwined assembly 12is also kept in proper angu-
`tial space respectively defined by the cases A1, A2 and
`Bl
`lar alignmentrelative to the carrier 13 by means such as
`It will be noted from FIG.4 that when the outer cases
`an outwardly-directed key 25 formed on oneside of the
`upper base support 18 to be received within a comple-
`29 are stacked together to arrange the intertwined as-
`mentary inwardly-facing longitudinal groove 26 near
`sembly 12, the rear faces of the frustoconical rearward
`the upper end ofthe carrier.
`portions of the outer cases cooperate to define an axial
`In the depicted embodimentofthe perforating appa-
`passage, as at 30, which has a generally-triangular cross-
`ratus 10 of the present invention, each shaped charge 11
`section and extends through the intertwined assembly.
`includes an inner container or hollow case 27 ofa suit-
`As seen in FIGS. 4 and 6, the rearward portions of the
`able metal, such as zinc, which is symmetrically formed
`inner charge cases 27 are preferably arranged to define
`about its longitudinal axis 20 to define a frustoconical
`an axial projection, as at 31, which is sized to extend
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`another stacked structure as at B. On the other hand, the
`vertical height of each of the forward bosses 37 and 39
`must be coordinated to achieve a desired spacing be-
`tween the adjacent cases 29 in the same stacked struc-
`ture.as at A, B or C. Forinstance, as best seen in FIG.
`1, it should be recognized that the combined heights of
`the rearward bosses 36 and 38 determines the vertical
`spacing between the longitudinal axis 20 of the case Al
`and the longitudinal axis 20 of the adjacent case C1.
`Similarly, the combined heights of the rearward boss 36
`on the case C1 and the rearward boss 38 on the case B2
`(neither boss seen in FIG. 1) will determine the vertical
`spacing betweenthe longitudinalaxis of these two outer
`cases.
`
`7
`through an opening in the rear of each of the outer cases
`29into the axial passage 30 of the intertwined assembly
`12. Asis typicaly, rearwardly-openingslots, as at 32, are
`cooperatively arranged transversely across the projec-
`tions 31 and appropriately shaped to snugly receive the
`adjacent portion of a detonating cord 33. passing
`throughthe axial passage 30. To position the detonating
`cord 33 within detonating proximity of the primer ex-
`plosive within each shaped charge 11, the inner cases 27
`are fabricated either with a hole in the wall between the
`primer and the detonating cordor bysufficiently reduc-
`ing the thickness of this wall so as to achieve high-order
`detonation of the charge.Asillustrated in FIG.7, it will
`be noted that the slots 32 are preferably cut at an angle
`of 26.5-degrees from the vertical so that the detonating
`cord 33 will follow a somewhat convoluted or zig-zag-
`ging path through the center passage 30 in the inter-
`twined assembly 12. To maintain the inner cases 27 in
`proper angular alignment with respect to the outer
`cases 29, retaining means such as longitudinal keys and
`grooves, as at 34 and 35, are cooperatively arranged on
`the forward portions of the inner and outer cases and
`adapted to be mated together when the inner cases are
`fitted into the outer cases as the perforating apparatus
`10 is being assembled.
`Turning now to FIGS. 5-7 showing elevational
`views of a preferred embodiment of the outer cases 29
`of the invention, it will be noted that each of the outer
`cases 29 is provided with upper and lower support
`means 34 and 35 cooperatively arranged to provide
`upwardly-facing and downwardly-facing abutmentsur-
`faces which respectively lie in parallel transverse planes
`spatially disposed above and below the central axis 20 of
`the outer case. It is also preferred to arrange the upper
`and lower support means 34 and 35 on opposite sides of
`the outer cases 29 in the form of upwardly-directed
`integral bosses 36 and 37 which are spatially disposed
`on the upper surfaces of the outer cases and downward-
`ly-directed integral bosses 38 and 39 which are spatially
`disposed on the lower surfaces of the outer cases. As
`best seen in FIG. 5, the upper bosses 36 and 37 are
`respectively shaped to define flat abutment surfaces 40
`and 41 lying in parallel transverse planes which are
`parallel to the longitudinal axis of the charge case 29.
`Similarly, the lower bosses 38 and 39 are respectively
`arranged with flat abutment surfaces 42 and 43 lying in
`separate parallel transverse planes which are below the
`axis 20 and also parallel to the axis as well as to the
`transverse planes passing through the upper abutment
`surface 40 and 41.
`It will be noted that the upper and lower bosses 37
`and 39 are respectively located just behind the forward
`end of each of the outer cases 29 and arelaterally offset
`by only a short distance in relation to the central longi-
`tudinal axis 20 of the case. Conversely, the upper and
`lowerbosses 36 and 38 are each located well behind the
`forward ends of the outer cases 29 and are laterally
`offset by a greater distance in relation to the longitudi-
`nal axis 20 of the case. With this configuration of the
`upper and lower bosses 36-39, it will be appreciated
`that each of the outer cases 29 will be firmly supported
`within the stack of charges 11 in the assembly 12 and
`adequately restrained against being misaligned with
`respect to their respective blind bores 16. It should also
`be realized that the vertical height of each of the rear-
`wardbosses 36 and 38 must be coordinated to achieve a
`desired vertical spacing between the cases 29 in one
`stacked structure, as at A, and the adjacent cases in
`
`Althoughthis relationship is not evident form FIG.1,
`it will be appreciated that the overall height of the
`rearward bosses 36 and 38 will similarly determine the
`vertical spacing between the cases 29 in the structure C
`and the outer cases in the stacked structure B as well as
`the spacing between the outer cases in the stacked struc-
`ture B and those in the structure A. On the other hand,
`it will be realized from FIG.1 that the combined verti-
`cal height of the forward bosses 37 and 39 on the outer
`cases Al and A2 controls the vertical spacing between
`those cases 29. Likewise, the combined height of the
`forward bosses 37 and 39 will also determine the verti-
`cal spacing between the central axes 20 of the cases 29
`in the stacked structure B as well as the vertical spacing
`between the axes of the outer cases in the stacked struc-
`ture C. It will, of course, be recognized from FIG. 1
`that the heights of each of these several bosses 36-39
`must be coordinated in accordance with the maximum
`diameter of the forward portions of the outer cases 29 as
`well as the diameter of the rearward frustoconical por-
`tions of these cases at the nearest points of contact be-
`tween the adjacent outer cases. Those skilled in the art
`will, therefore, appreciate that for a given inside diame-
`ter of the carrier 13, consideration must be given to the
`diameter and overall length of the particular shaped
`charges 11 that are to be used in the carrier to arrive at
`an optimumsize for the charges and a minimum vertical
`spacing between adjacent charges.
`Referring again to FIGS. 4-7, it will be seen that in
`the preferred embodiment of the outer cases 29 of the
`invention, alignment means, as shown generally at 44,
`are arranged on each outer case to maintain them in
`angular alignment with one another when the inter-
`twined assembly 12 is assembled. In the depicted em-
`bodiment of the outer cases 29, the alignment means 44
`include interfitting pins, such as at 45 and 46 on the
`lower bosses 38 and 39 respectively, and sockets, such
`as at 47 and 48 on the upper bosses 36 and 37 respec-
`tively. It will, therefore, be realized that as the several
`outer cases 29 are being stacked, the pins 45 and 46 on
`one outer case will be fitted into the mating sockets 47
`and 48 in the adjacent cases so that the outer cases will
`be retained against rotation relative to one another.
`Asbest seen in FIG.1, it will be recognized that to
`longitudinally offset the several outer cases 29 in each
`of the stacked structures A, B and C in relation to one
`another, the lower base member 19 is cooperatively
`arranged to support the lowermost charge case, as at
`Ai, B1 and C1, in each stacked structure at a different
`elevation above the base member. Thus, as shown in
`FIGS. 1 and 3,
`the lower base 19 includes support
`means such aslaterally-spaced upright posts 49 and 50
`that are are located on the base memberto be respec-
`tively aligned with the lower bosses 38 and 39 on the
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`35
`
`60
`
`65
`
`Hunting Titan, Inc.
`Ex. 1003
`Pg. 008
`
`Hunting Titan, Inc.
`Ex. 1003
`Pg. 008
`
`

`

`4,744,424
`
`9
`lower charge case Al whenthecase is correctly posi-
`tioned on top of the base member. Since the lower abut-
`ment surface 42 and 43 are at different elevations in
`relation to the central axes 20, it will be appreciated that
`the height of the upright posts 49 and 50 must be appro-
`priately arranged to support the outer case Al in its
`illustrated position on the lower base member 19. To
`maintain the lowermost case Al in proper angular
`alignment with respect to the lower base member 19,
`retaining means such as upwardly-directed sockets 51
`and 52 are appropriately arranged in the upper portions
`of the posts 49 and 50 for respectively receiving the
`depending pins 45 and 46 on the outercase. In a similar
`fashion, a second set of posts 53 and 54 are located on
`the lower base 19 to be in alignment with the lower
`bosses 38 and 39 on the outer charge case B1 and a
`anotherpost 55 is located on the baseto be in alignment
`with the outer case C1. The otherside of the case C1 is
`supported on the adjacentside of the case A1. It should
`be understood that the lengths of the posts 53-55 are
`respectively arrangedso as to position the charge cases
`B1 and C1 at the appropriate elevations above the base
`member 19. Sockets 56-58 are also respectively ar-
`ranged in the upright posts 53-55 for retaining the
`charge cases B1 and C1in angularalignment on the base
`member19.
`Those skilled in the art will, of course, recognize that
`even underthe best of conditions, the perforating appa-
`ratus 10 will be subjected to substantial impact forces as
`it is being positioned in a weil bore. Accordingly, to be
`certain that the stacked structures A, B and C are well
`supported against such impact forces, additional upright
`posts 59-61 are cooperatively arranged on the lower
`base member 29 for respectively engaging the lower
`surfaces of