A through tubing stripgun detonating charge assembly for well perforating activities, comprising an elongate explosive resistant retrievable perforating charge support strip having a perforating charge interlocking track situate along the length thereof. A plurality of explosive well casing perforating charges having support elements thereon are connected in supporting and selective positioning interlocking engagement with the perforating charge interlocking track for support of certain ones of a plurality of perforating charges in 180 degree phase oriented and adjustably positionable relation on the perforating charge support strip. The perforating charge strip is also provided with a plurality of perforating charge connectors in spaced relation along the length thereof for support of a plurality of perforating charges in 0 degree phase relation with the perforating charge support strip and in 90 degree phase orientation with each of the 180 degree phased perforating charges. The charge interlocking track may have a dove-tailed cross-sectional configuration for interlocking relation with locking grooves of corresponding relation in certain of the perforating charges. Set screws or charge spacers are used to secure the perforating charges against movement relative to the retrievable support strip.

FIELD OF THE INVENTION 
This invention relates generally to perforating guns that are utilized to 
perforate well casings at the level of production zones to thereby 
complete the well for production of petroleum products from the production 
zone, More specifically, the present invention concerns the provision of a 
two and three phased through tubing stripgun for casing perforation, 
having encapsulated explosive shaped charges having the capability of 
selective positioning thereof along the length of a charge carrier strip 
that remains intact upon detonation of the explosive charges and thereby 
minimizes the debris that is left in the well bore upon firing of the 
perforating gun. 
BACKGROUND OF THE INVENTION 
Perforating guns that are used to perforate well casings after passing 
through a small diameter production tubing may be made up of individually 
encapsulated, pressure tight shaped explosive charges which are supported 
in spaced and specifically oriented positions along the length of a charge 
carrier section of the perforating gun. "Through tubing" perforating guns 
are small in diameter relative to the well casing, limiting the explosive 
powder load that is available for explosive preparation; consequently the 
penetration and phasing of the perforated holes as well as the amount and 
type of debris left in the well by the detonated perforating gun are 
important considerations. 
Small diameter "through tubing" perforating guns utilizing encapsulated 
explosive charges are typically of two general types: in one type of 
perforating gun the encapsulated explosive charges are linked together as 
a chain leaving as debris in the well all of the metallic material in the 
perforating gun. Link-type perforating guns configured in a spiral firing 
pattern loose efficiency on the particular explosive charge shots that 
must fire across large diameter fluid filled casings before penetrating 
the formation surrounding the well casing. 
The second general type of "through tubing" perforating gun utilizes 
in-line firing charges that are mounted on explosive resistant steel 
carrier strips having the capability of withstanding the explosive 
detonation of the charges and remaining intact so that the carrier strips 
may be retrieved after casing perforation activity has been accomplished. 
For the reason that the steel carrier strips are retrieved after firing of 
the perforating gun, thus only the debris of the charged cases will remain 
in the well after the perforating gun has been fired and retrieved. 
In-line firing stripguns are positioned in the well casing so that all of 
the charges fire with zero clearance directly into the casing, maximizing 
the diameter of the perforated holes in the casing and penetration of the 
explosive energy into the formation, yielding in general higher 
productivity than wells perforated with spiral phased through tubing type 
perforating guns. More recently, a through tubing stripgun has been 
developed, as indicated by U.S. Pat. No. 5,095,999 of Markel. This patent 
discloses an explosive resistant carrier strip which is configured to 
orient explosive charges so that the penetration jets of the charges are 
directed 45.degree. apart. Thus, when this type of stripgun establishes a 
line of contact with the well casing each line of explosive charges is 
oriented at plus or minus 22.5.degree. from the line of contact. This type 
of two phased through tubing perforating gun establishes a 90.degree. shot 
pattern which offers some advantage over the single phased in-line 
configuration that is normal with most stripguns. 
The need for the carrier strip of a stripgun type through tubing 
perforating gun to remain intact when the perforating gun is detonated and 
the small dimension of the tubing through which the stripgun must pass to 
reach the downhole zone where casing perforation is desired typically 
limits stripguns to two phase charge orientation as shown by U.S. Pat. No. 
5,095,999. If greater than two charge orientation with the type of carrier 
strip shown by this patent the carrier strip can be severed by the 
explosive detonation. It is important that the carrier strip be capable of 
withstanding the explosive detonation so that it can be retrieved from the 
well, thereby leaving only minute charge case debris to settle to the 
bottom of the well bore. It is desirable however to provide a through 
tubing stripgun capability enabling one, two or three phased charge 
orientation and yet insuring that the carrier strip of the stripgun will 
withstand the explosive detonation so that it may be retrieved from the 
well. It is also desirable to provide a through tubing stripgun that is 
provided with the capability of selectively orienting the location of the 
shaped charges along the length of the stripgun so that field personnel 
may select both the phase orientation and the vertical charge spacing as 
appropriate to the character of casing perforation that is desired. 
SUMMARY OF THE INVENTION 
It is a principal feature of the present invention to provide a through 
tubing type stripgun for achieving well perforation activities and by 
providing an explosive carrier strip that is capable of withstanding 
explosive detonation of the perforating charges so that it may be 
retrieved from the well along with other portions of the perforating gun. 
It is a further feature of this invention to provide a novel multiphased 
through tubing stripgun which permits selective phase orientation of the 
perforating charges as desired for specific casing perforation and which 
also permits selective vertical spacing of the shaped charges relative to 
the carrier strip so that the well completion shots may be selectively 
oriented from the standpoint of both angular phase and vertical spacing as 
desired at the time of well perforation. 
It is an even further feature of this invention to provide a novel through 
tubing type multiphased stripgun having undercut slots such as dove-tail 
slots along the length thereof and providing shaped charge mounting basis 
that are received by the undercut slots to thereby permit vertical 
orientation of the shaped charges at any selected location along the 
length of the carrier strip. 
It is another feature of this invention to provide a novel through tubing 
stripgun wherein simple and efficient stops are utilized to secure the 
shaped charges at selected positions along the length of the carrier 
strip. 
It is an even further feature of this invention to provide a novel through 
tubing type stripgun assembly wherein selected spacing of perforated 
charges along the length of the stripgun may be stabilized by means of 
track mounted spacers that are positioned between the explosive charges. 
It is another feature of this invention to provide a novel multiphased 
through tubing stripgun having an explosive resistant carrier strip and 
having explosive charge mounting basis that may be reversibly oriented 
relative to the track of the carrier strip so as to permit selective 
orientation of the explosive charges relative to the carrier strip. 
Briefly a multiphased through tubing stripgun constructed in accordance 
with the present invention will comprise an elongate explosive charge 
carrier strip of a length that is suitable for the casing perforation 
activity under consideration. The elongate carrier strip will be of 
sufficient cross-sectional dimension to effectively withstand detonation 
of the shaped charges so that it will remain intact when the charges are 
detonated and may be retrieved from the well along with other casing 
perforation equipment. The elongate carrier strip will define a track 
extending along the length thereof and the casings or mounting bases of 
the sealed shaped charges will have portions interfitting with the 
elongate track and serving to retain the shaped charges at desired phase 
orientation. The elongate carrier strip may also define apertures at 
spaced locations along the length thereof thereby committing specific 
charges of the shaped charge array to be oriented in a manner to project 
the explosive jets thereof through the apertures in the carrier strip so 
that these explosive jets will penetrate the tubing and casing and project 
well into the formation surrounding the well casing. 
If desired, the elongate track means of the carrier strip may be defined by 
a dovetail projection or dove-tail groove. In this case the sealed shaped 
charges will be provided with corresponding projections or grooves thereby 
enabling them to be positioned at selected locations along the length of 
the carrier strip simply by moving them along the length of the track. 
When the explosive charges are properly positioned relative to the length 
of the carrier strip the shaped charges may be locked in place by means of 
set screws or may be retained in position by spacers that are also 
received by the track of the carrier strip. Thus, it seen that the through 
tubing stripgun of the present invention will have the capability of one, 
two or three phased orientation of the shaped charges and will have the 
capability of selective vertical positioning of the shaped charges along 
the length of the carrier strip.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring now to the drawings and first to FIGS. 1-3 a through tubing type 
multiphased stripgun for well casing perforation is shown generally at 10 
and incorporates a perforator head 12 which is adapted such as by threads 
for connection to a suitable running tool such as a wireline running tool 
or any other component of a perforating gun system. The perforating head 
is provided with an elongate coupling extension 20 having openings 22 and 
24 therein for receiving bolts or screws 26 and 28 that serve to connect 
an elongate explosive carrier strip 30 to the coupling extension 20. The 
carrier strip 30 is adapted as will be explained herein below for 
supporting a plurality of sealed shaped charge elements such as shown at 
32, 34 and 36 so that the shaped charges are oriented for multiphased 
projection of the explosive jets thereof through the well casing and into 
the surrounding formation. With regard to FIGS. 1 and 2 it should be noted 
that the explosive charges 32 and 36 have phase orientation of 180.degree. 
with respect to one another. The explosive charge 34 has a phase 
orientation of 90.degree. with respect to each of the explosive charges 32 
and 36. 
At the lower extremity of the carrier strip 30 there is provided a coupling 
plate 38 which, as shown in FIGS. 1 and 2, provides for connection of a 
lower guide element 40 to the lower end of the carrier strip. The coupling 
plate 38 is connected to the carrier strip by bolts 42 and connected by 
bolts 44 to the guide nose 40. A guide element 46 is secured in fixed 
relation to the coupling plate by the upper bolt 42 and is secured at its 
lower end to the guide nose 40 by means of guide connector 48. The guide 
element 46 will traverse the internal surface of the tubing thus causing 
the carrier strip 30 to be oriented in engagement with the tubing. 
A detonating cord 50 extends along the length of the perforating gun and is 
operatively coupled to each of the shaped charges thereof. The detonating 
cord, when detonated, causes simultaneous initiation of each of the shaped 
charges. 
As shown in FIG. 3, it may be appropriate to interconnect two or more 
carrier strips 30 end to end so as to insure that the casing section 
spanning the formation of interest is perforated along its entire length. 
As shown in FIG. 3 carrier strip sections 30 are oriented in substantially 
abutting relation as shown at 52 each of the carrier strips will define a 
pair of bolt holes at the respective ends thereof which are positioned in 
registry with appropriate bolt holes defined in a coupling plate 54. 
Which, if desired, may be identical with the coupling plate 38. Bolts 56 
and 58 are employed to secure the respective carrier strips to the 
coupling plate. The length of detonating cord will simply extend from the 
shaped charges of the upper carrier strip to the shaped charges of the 
lower carrier strip. All of the shaped charges will be simultaneously 
initiated by detonation of the detonating cord. 
Referring now to FIG. 4 there is provided a cross-sectional illustration of 
a well casing shown in broken line at 60 and having the through tubing 
stripgun 10 located therein with the charge support strip 30 in engagement 
with the internal wall surface 62 of the well casing. The circular broken 
line 64 is representative of the maximum cross-sectional diameter of the 
stripgun which enables it to traverse through a production tubing within 
the casing to reach the production interval of the surrounding formation. 
As shown in FIGS. 4-7 each of the sealed shaped charges 32, 34 and 36 
define a charge body or casing 66 which is of generally cylindrical 
configuration and which is provided with a domed type charge cap 68 of 
generally frusto-conical configuration and which is secured in sealed 
relation to the charge body 66. Internally, the charge body is of 
substantially cylindrical configuration as is evident from FIG. 9. The 
charge body, at the end thereof opposite the domed type charge cap 68 
defines a detonating cord groove 70 which may be of smoothly curved 
configuration as shown in FIG. 6. Adjacent the detonating cord groove 70 
the charge body 66 defines opposed recesses 72 and 74 which receive 
respective ends of a retainer clip 76 that secures the detonating cord 50 
within its groove 70. The retainer clips 76 also function as guide 
elements which may contact to the internal wall surface of the tubing 
string as the stripgun is moved to its casing perforation depth. These 
clips also provide standoff between the internal wall surface of the 
tubing string and the detonating cord so as to protect the detonating cord 
against erosion as the stripgun traverses the tubing string. 
It is desirable to provide for adequately securing the casing perforation 
charges at desired locations along the length of the carrier strip 30 and 
to insure against inadvertent movement of the perforation charges as the 
stripgun is run through the tubing string. In the case of the three phased 
casing perforation embodiment of FIGS. 1 and 2 a number of the shaped 
charges, such as the charges 34 are intended to be connected to the 
carrier strip at specific locations along the length thereof. Though the 
other shaped charges 32 and 36 may also be specifically located along the 
length of the carrier strip, in practice they may be shifted along the 
length of the stripgun to positions other than as shown in FIGS. 1 and 2. 
In the case of the dual 180.degree. phased stripgun of FIG. 5, all of the 
shaped charges thereof may be selectively positioned along the length of 
the carrier strip 30. These desirable features are effectively provided by 
defining an elongate track along the length of the carrier strip and by 
providing at least some of the shaped charges with the capability of 
adequate support and selective positioning relative to the guide track. As 
shown in FIGS. 4-11 the guide track of the carrier strip may conveniently 
take the form of a dove-tailed projection 78 which is oriented 
substantially centrally of the carrier strip. Correspondingly, the 
generally cylindrical charge bodies of certain of the shaped charges, i.e. 
shaped charges 32 and 36 are configured to define dove-tailed slots 80 
which receive the elongate dove-tailed projection 78 of the carrier strip 
and thus establish a mechanically interlocked relation with each of the 
charge bodies of shaped charges 32 and 36. The interlocked dove-tailed 
connection between the carrier strip 30 and the body structure of the 
shaped charges provides for precise lateral orientation of the shaped 
charges so that the charge jet direction thereof is oriented at a phase of 
180.degree. as shown in FIG. 4. 
As shown in FIG. 16 a carrier strip 31 may be provided to which may be 
connected a track strip 79 which may be of dove-tailed cross-sectional 
configuration as shown or which may be of any other cross-sectional 
configuration as suits the intended purpose of the user or which is 
appropriate for the well completion activity that is intended. For example 
the dove-tailed charge mounting strip 79 may have a desired angular 
orientation with respect to the carrier strip 31 to achieve desired phase 
orientation of the charges 32 and 36 with respect to the phase orientation 
of the charges 34. Selected phase orientation of the charges may thus be 
achieved simply by attachment of mounting strips having selected angular 
orientation with respect to the carrier strip. The mounting strip 79 may 
be secured to the carrier strip by screws or bolts 81 which extend through 
holes 83 of the carrier strip and are received by threaded holes 85 of the 
mounting strip. If desired the screws or bolts 81 may also enter threaded 
openings of the explosive charge bodies to also secure the charges against 
axial movement relative to the mounting strip and carrier strip. 
While explosive charges 34 fire directly through the threaded charge 
attachment openings of the carrier strip other charges, such as charges 32 
and 36 may assume other angular displacements than the 90.degree. phase 
displacement from the charge 34 orientation that is shown in FIGS. 1 and 
2, resulting in other phase orientations that are suitable for some well 
conditions. This is accomplished simply by controlling the angle of the 
charge connection system of the charges 32 and 36. For example, the 
dove-tailed slot 80 may be oriented with respect to the charge body 66 
such that the angular phase orientation of the charge will be angularly 
offset from that of charge 34 by a predetermined angle other than 
90.degree.. For example charges 32 and 36 may establish phase angles of 
plus and minus 45.degree. with respect to charge 34 simply by orienting 
the angular relation of the dove-tailed slot in the charge body to define 
such phase orientation. Obviously the elongate track may also be angularly 
oriented in controlled manner relative to the carrier strip to achieve 
desired phase orientation of the various charges. 
It will be desirable to secure the shaped charges 32 and 36 against 
longitudinal movement relative to the carrier strip. As shown in FIGS. 7, 
9 and 10 one suitable means for locking the respective shaped charges 
against inadvertent movement along the length of the carrier strip may 
comprise a pair of set screws 82 and 84 which are received within 
internally threaded openings 86 and 88, respectively. These set screws, 
when threaded through the carrier strip will project beyond the 
dove-tailed projection 78 and will engage respective sides of the charge 
bodies 66 as shown in FIG. 9. If desired, the set screw holes 86 and 88 
may be formed in the carrier strip during manufacturing thereof so that 
the 180.degree. phased shaped charges will be located relative to the 
carrier strip by the manufacturing operation. In the alternative, the set 
screw holes may be drilled and tapped in the field just prior to running 
of the perforation gun. Thus, especially in the case of the dual phased 
stripgun of FIG. 5 the shaped charges may be individually located relative 
to the length of the carrier strip simply by appropriate positioning of 
the threaded set screw holes. 
As shown in FIGS. 14 and 15 the spacer strips 90 may be composed of stamped 
or formed sheet material such as metal having a generally planar body 
section 91 and angularly oriented edge flanges 93 and 95 which define an 
internal receptacle 97 within which is received the dove-tailed projection 
78. The mounting bolts 94 are then extended through apertures 99 to secure 
the spacer elements to the carrier strip 30. The sheet material spacer 
elements can be of quite inexpensive manufacture without detracting from 
the effectiveness of the strip charge assembly. 
As an alternative to set screw retention of the shaped charges as shown in 
FIGS. 7, 10 and 11 charge spacer elements may be provided having dove-tail 
grooves that receive the dove-tail projection 78 of the carrier strip. 
These spacer elements may interposed between and in contact with the 
respective shaped charges so as to secure them in the selected position. 
The spacer strips may be of various selected length so as to achieve 
selected positioning of the shaped charges relative to the carrier strip. 
If desired, the spacer elements may be secured by bolts or screws 94 to 
the carrier strip. 
It may also be desirable to fix the perforating charges 34 so that the 
explosive jets thereof will be oriented 90.degree. with respect to the 
phases of the perforating charges 32 and 36. As shown in FIGS. 9 and 11 
the carrier strip 30 will be machined to define threaded openings such as 
shown at 98, which receive the external threads of a threaded charge cap 
100. The carrier strips are further machined to define beveled recesses 
102 that correspond to the configuration of the external tapered surface 
104 of the end cap 106. Thus, perforating charges 34 will be maintained in 
threaded assembly with the carrier strip 30 as shown particularly in FIGS. 
9 and 11 while the perforating charges 32 and 36 will be secured to the 
carrier strip by the interlocking track assembly such as the dove-tail 
projection and groove assembly shown in FIGS. 4-7. 
It is to be borne in mind that although the invention is described herein 
particularly through the provision of a dove-tail type track 
interconnection between the perforating charges and the carrier strip it 
is not intended to limit the spirit and scope of the invention to this 
particular structure. It should be borne in mind that any suitable 
interengaging track arrangement that is capable of being employed to 
secure the perforating charges in selectively positioned assembly with the 
elongate carrier strip may be employed within the spirit and scope of this 
invention. 
Various modifications and alterations in the described methods and 
apparatus will be apparent to those skilled in the art of the foregoing 
description which does not depart from the spirit of the invention. For 
this reason, such changes are desired to be included in the appended 
claims. The appended claims recite the only limitation to the present 
invention. The descriptive manner which is employed for setting forth the 
embodiments should be interpreted as illustrative but not limitative.