Patent Publication Number: US-11649684-B2

Title: Perforating gun

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date of, and priority to, U.S. Patent Application No. 63/224,338 (the “&#39;338 Application”), filed Jul. 21, 2021, the entire disclosure of which is hereby incorporated herein by reference. 
     This application also claims the benefit of the filing date of, and priority to, U.S. Patent Application No. 63/355,440 (the “&#39;440 Application”), filed Jun. 24, 2022, the entire disclosure of which is hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to perforating guns used in oil and gas completions operations, and, more particularly, to a perforating gun with one or more centralizing charge tube inserts and, optionally, an orienting centralizer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exploded top-front-right-perspective view of a first perforating gun including a first charge cartridge, a first carrier tube, and a first conductor sub. 
         FIG.  2    is an exploded top-front-right-perspective view of the first charge cartridge of  FIG.  1   , which first charge cartridge includes a first charge tube, first and second cap assemblies, and first and second centralizing inserts, according to one or more embodiments. 
         FIG.  3 A  is a top-front-right-perspective view of an end cap of the first cap assembly of  FIG.  2   , according to one or more embodiments. 
         FIG.  3 B  is a rear elevational view of the end cap of  FIG.  3 A , according to one or more embodiments. 
         FIG.  4    is a cross-sectional view of the first cap assembly of  FIG.  2    taken along the line  4 - 4  of  FIG.  2   , according to one or more embodiments. 
         FIG.  5 A  is a top-front-right-perspective view of the first charge tube of  FIG.  2   , according to one or more embodiments. 
         FIG.  5 B  is a right side elevational view of the first charge tube of  FIG.  2   , according to one or more embodiments. 
         FIG.  5 C  is a cross-sectional view of the first charge tube of  FIG.  2    taken along the line  5 C- 5 C of  FIG.  5 A , according to one or more embodiments. 
         FIG.  5 D  is a top plan view of the first charge tube of  FIG.  2    according to one or more embodiments. 
         FIG.  5 E  is a cross-sectional view of the first charge tube of  FIG.  2    taken along the line  5 E- 5 E of  FIG.  5 A , according to one or more embodiments. 
         FIG.  6 A  is a top-front-right-perspective view of the first centralizing insert of  FIG.  2   , according to one or more embodiments. 
         FIG.  6 B  is a front elevational view of the first centralizing insert of  FIG.  2   , according to one or more embodiments. 
         FIG.  7 A  is a cross-sectional view of the first charge cartridge of  FIG.  2    taken along the line  7 A- 7 A of  FIG.  1   , illustrating, in an assembled state, a first end portion of the first charge tube, the first cap assembly, and the first centralizing insert, according to one or more embodiments. 
         FIG.  7 B  is a cross-sectional view of the first charge cartridge of  FIG.  7 A  taken along the line  7 B- 7 B of  FIG.  7 A , according to one or more embodiments. 
         FIG.  8 A  is a top-front-right-perspective view of the second centralizing insert of  FIG.  2   , according to one or more embodiments. 
         FIG.  8 B  is a front elevational view of the second centralizing insert of  FIG.  2   , according to one or more embodiments. 
         FIG.  9 A  is a cross-sectional view of the first charge cartridge of  FIG.  2    taken along the line  9 A- 9 A of  FIG.  1   , illustrating, in an assembled state, a second end portion of the first charge tube, the second cap assembly, and the second centralizing insert, according to one or more embodiments. 
         FIG.  9 B  is a cross-sectional view of the first charge cartridge of  FIG.  9 A  taken along the line  9 B- 9 B of  FIG.  9 A , according to one or more embodiments. 
         FIG.  10    is a cross-sectional view of the first carrier tube of  FIG.  1    taken along the line  10 - 10  of  FIG.  1   , according to one or more embodiments. 
         FIG.  11    is a cross-sectional view of the first conductor sub of  FIG.  1    taken along the line  11 - 11  of  FIG.  1   , according to one or more embodiments. 
         FIG.  12 A  is a cross-sectional view of the first perforating gun of  FIG.  1    in a first operational state or configuration, according to one or more embodiments. 
         FIG.  12 B  is a cross-sectional view of the first perforating gun of  FIG.  1    in a second operational state or configuration, according to one or more embodiments. 
         FIG.  12 C- 1    is a cross-sectional view of the first perforating gun of  FIG.  1    in a third operational state or configuration, according to one or more embodiments. 
         FIG.  12 C- 2    is an enlarged cross-sectional view of the first perforating gun of  FIG.  12 C- 1    in the third operational state or configuration, according to one or more embodiments. 
         FIG.  12 D- 1    is a cross-sectional view of the first perforating gun of  FIG.  1    in a fourth operational state or configuration, according to one or more embodiments. 
         FIG.  12 D- 2    is an enlarged cross-sectional view of the first perforating gun of  FIG.  12 D- 1    in the fourth operational state or configuration, according to one or more embodiments. 
         FIG.  12 E  is a cross-sectional view of the first perforating gun of  FIG.  1    in a fifth operational state or configuration, according to one or more embodiments. 
         FIG.  13    is a diagrammatic illustration the first perforating gun of  FIG.  1    assembled together with another perforating gun, according to one or more embodiments. 
         FIG.  14    is an exploded top-front-right-perspective view of a second perforating gun including a second charge cartridge, a second carrier tube, and a second conductor sub. 
         FIG.  15    is an exploded top-front-right-perspective view of the second charge cartridge of  FIG.  1   , which second charge cartridge includes a second charge tube, third and fourth cap assemblies, a third centralizing insert, and an orienting centralizer, according to one or more embodiments. 
         FIG.  16 A  is a top-front-right-perspective view of the second charge tube of  FIG.  15   , according to one or more embodiments. 
         FIG.  16 B  is a right side elevational view of the second charge tube of  FIG.  15   , according to one or more embodiments. 
         FIG.  16 C  is a cross-sectional view of the second charge tube of  FIG.  15    taken along the line  16 C- 16 C of  FIG.  16 A , according to one or more embodiments. 
         FIG.  16 D  is a top plan view of the second charge tube of  FIG.  15   , according to one or more embodiments. 
         FIG.  16 E  is a cross-sectional view of the second charge tube of  FIG.  15    taken along the line  16 E- 16 E of  FIG.  16 A , according to one or more embodiments. 
         FIG.  17 A  is a cross-sectional view of the second charge cartridge of  FIG.  15    taken along the line  17 A- 17 A of  FIG.  14   , illustrating, in an assembled state, a first end portion of the second charge tube, the third cap assembly, and the third centralizing insert, according to one or more embodiments. 
         FIG.  17 B  is a cross-sectional view of the second charge cartridge of  FIG.  17 A  taken along the line  17 B- 17 B of  FIG.  17 A , according to one or more embodiments. 
         FIG.  18 A  is a cross-sectional view of the orienting centralizer of  FIG.  15   , taken along the line  18 A- 18 A of  FIG.  14   , according to one or more embodiments. 
         FIG.  18 B  is a front elevational view of the orienting centralizer of  FIG.  15   , according to one or more embodiments. 
         FIG.  19 A  is a cross-sectional view of a portion of the second conductor sub of  FIG.  14    taken along the line  19 A- 19 A of  FIG.  14   , according to one or more embodiments. 
         FIG.  19 B  is a rear elevational view of the second conductor sub of  FIG.  14   , according to one or more embodiments. 
         FIG.  20    is a cross-sectional view of the second carrier tube of  FIG.  14    taken along the line  20 - 20  of  FIG.  14   , according to one or more embodiments. 
         FIG.  21 A  is an enlarged cross-sectional view of the second perforating gun of  FIG.  14    in a first operational state or configuration, according to one or more embodiments. 
         FIG.  21 B  is an enlarged cross-sectional view of the second perforating gun of  FIG.  14    in a second operational state or configuration, according to one or more embodiments. 
         FIG.  21 C  is an elevational view of the second perforating gun of  FIG.  14    in a third operational state or configuration, according to one or more embodiments. 
         FIG.  21 D- 1    is an elevational view of the second perforating gun of  FIG.  14    in a fourth operational state or configuration, according to one or more embodiments. 
         FIG.  21 D- 2    is an enlarged cross-sectional view of the second perforating gun of  FIG.  21 D- 1    in the fourth operational state or configuration, according to one or more embodiments. 
         FIG.  21 E  is an enlarged cross-sectional view of the second perforating gun of  FIG.  14    in a fifth operational state or configuration, according to one or more embodiments. 
         FIG.  21 F  is an elevational view of the second perforating gun of  FIG.  14    in a sixth operation state or configuration, according to one or more embodiments. 
         FIG.  21 G  is a cross-sectional view of the second perforating gun of  FIG.  14    in a seventh operational state or configuration, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG.  1   , in one or more embodiments, a perforating gun is generally referred to by the reference numeral  100 . The perforating gun  100  includes a charge cartridge  105 , a carrier tube  110 , and a conductor sub  115 . The charge cartridge  105  is adapted to house ballistic(s), which ballistic(s) include a singular or plurality of perforating charges and detonator cord, detonable to perforate a wellbore proximate a subterranean formation. The carrier tube  110  receives the assembled charge cartridge  105 , including the ballistic(s), a detonator, and (optionally) a switch. The conductor sub  115  is adapted to: axially trap the charge cartridge  105  within the carrier tube  110 ; and conduct electricity to and/or from the charge cartridge  105  to facilitate detonation of the ballistic(s). 
     Referring to  FIG.  2   , in one or more embodiments, the charge cartridge  105  includes a charge tube  120 , cap assemblies  125   a - b , centralizing inserts  130   a - b , and (optionally) the switch (e.g., an addressable switch). The cap assemblies  125   a - b , the centralizing inserts  130   a - b , and (optionally) the switch are configured to be toollessly assembled with the charge tube  120  (e.g., without fastener(s)). 
     Referring to  FIGS.  3 A and  3 B , in one or more embodiments, the cap assembly  125   a  includes an end cap  135 . The end cap  135  includes an end plate  140 , which end plate  140  is disk-shaped. One or more tabs  145  extend radially outwardly from an outer periphery of the end plate  140 . A conductor housing  150  extends axially from the end plate  140  in a direction  155   a . One or more latching features  160  extend axially from the conductor housing  150  in a direction  155   b , opposite the direction  155   a . In one or more embodiments, the latching feature(s)  160  are located along, or proximate, a circumference of a central aperture  165  of the end plate  140 . In one or more embodiments, the latching feature(s)  160  are radially-inwardly-facing. Additionally, one or more latching features  170  extend axially from the outer periphery of the end plate  140  in the direction  155   a . In one or more embodiments, the latching feature(s)  170  are located along, or proximate, an outer circumference of the end plate  140 . In one or more embodiments, the latching feature(s)  170  are outwardly-facing. The cap assembly  125   b  is substantially identical to the cap assembly  125   a , and, therefore, will not be described in further detail. 
     Referring to  FIG.  4   , in one or more embodiments, the cap assembly  125   a  includes the end cap  135 , a conductor body  175  (or “contact conductor”), a biasing member  180  (e.g., a spring), and an electrical connector  185 . The conductor body  175 , the biasing member  180 , and the electrical connector  185  are configured to be toollessly assembled with the end cap  135  (e.g., without fastener(s)). More particularly, the conductor body  175  and the biasing member  180  are inserted axially into the conductor housing  150 , as indicated by arrow  186 , via the central aperture  165  of the end plate  140 , causing the latching feature(s)  160  of the end cap  135  to latch onto the conductor body  175 , as indicated by arrows  187 , thereby trapping the conductor body  175  between the latching feature(s)  160  and an internal annular shoulder  190  of the end cap  135 . The electrical connector  185  extends through a central aperture  195  of the conductor housing  150 , opposite the central aperture  165  of the end plate  140 , fits over a reduced-diameter end portion  200  of the conductor body  175 , and is adapted to electrically connect a wire from the detonator and/or the switch to the conductor body  175 . In one or more embodiments, as in  FIG.  2   , the cap assembly  125   a  further includes a ground conductor  205  (e.g., toollessly coupled to the cap assembly  125   a , and/or coupled to the cap assembly  125   a  without fastener(s)) adapted to provide grounding electrical contact between the charge tube  120  and the carrier tube  110  when the charge tube  120  is received within the carrier tube  110 . In one or more embodiments, the ground conductor  205  is electrically coupled to ground (e.g., a ground “button” within the perforating gun  100 ) via a quick-connect wire (e.g., enabling toolless coupling of the ground conductor  205  to ground, and/or coupling of the ground conductor  205  to ground without fastener(s)). 
     Referring to  FIGS.  5 A through  5 E , in one or more embodiments, the charge tube  120  defines opposing end portions  210   a - b . Although shown as a single integrally formed body, the charge tube  120  may instead be broken into two or more interconnected components. An access port or window  215  is formed radially through the charge tube  120  at or proximate the end portion  210   a  of the charge tube  120 , which access port or window  215  permits access to an interior of the charge tube  120  at the end portion  210   a  of the charge tube  120 , permitting insertion of a detonator on-site during assembly of the perforating gun  100  and immediately before the perforating gun  100  is deployed into a wellbore. In one or more embodiments, the access port or window  215  extends spirally (e.g., helically) along the charge tube  120 ; this spiral extension of the access port or window  215  along the charge tube  120  helps to minimize, or at least decrease, a length L 1  of the charge tube  120  and, thus, an overall length L 2  of the perforating gun  100  (shown in  FIG.  12 D- 1   ). In one or more embodiments, the length L 1  of the charge tube is a maximum length of the charge tube. Additionally, circumferentially-opposing slots  220   a - b  are formed radially through the charge tube  120  at or proximate the end portion  210   a  of the charge tube  120 , via which slots  220   a - b  the centralizing insert  130   a  is insertable transversely through the charge tube  120  (as shown in  FIGS.  7 A and  7 B ). Similarly, circumferentially-opposing slots  225   a - b  are formed radially through the charge tube  120  at or proximate the end portion  210   b  of the charge tube  120 , via which slots  225   a - b  the centralizing insert  130   b  is insertable transversely through the charge tube  120  (as shown in  FIGS.  9 A and  9 B ). When so transversely inserted through the charge tube  120 , the centralizing inserts  130   a - b  are each spaced inwardly from the corresponding ends of the charge tube  120 . The charge tube  120  illustrated in  FIGS.  5 A through  5 E  is configured to rotationally align the perforating charges in a 120-degree phased relationship with adjacent one(s) of the perforating charges. 
     Referring to  FIGS.  6 A and  6 B , in one or more embodiments, the centralizing insert  130   a , which defines opposing end portions  230   a - b , includes one or more latching features  235  at or proximate the end portion  230   b  thereof. Additionally, an orienting key  240  extends radially from the centralizing insert  130   a  at the end portion  230   a.    
     Referring to  FIGS.  7 A and  7 B , in one or more embodiments, the cap assembly  125   a  and the centralizing insert  130   a  are assembled (e.g., toollessly and/or without fastener(s)) into the end portion  210   a  of the charge tube  120 . More particularly, the cap assembly  125   a  is inserted axially into the end portion  210   a  of the charge tube  120 , as indicated by arrow  241 , causing: the one or more tabs  145  to be received within corresponding axial recesses  245  formed into the charge tube  120  at the end portion  210   a ; and the latching feature(s)  170  of the end cap  135  to latch onto the charge tube  120  at corresponding slots  250  formed through the charge tube  120 , as indicated by arrow  242 . Additionally, the centralizing insert  130   a  is inserted transversely through the charge tube  120 , via the slots  220   a - b , as indicated by arrow  243 , causing: the latching feature(s)  235  of the centralizing insert  130   a  to latch onto the charge tube  120  at the slot  220   b , as indicated by arrows  244 ; and the opposing end portions  230   a - b  of the centralizing insert  130   a  to each extend radially beyond the charge tube  120 . 
     Referring to  FIGS.  8 A and  8 B , in one or more embodiments, the centralizing insert  130   b , which defines opposing end portions  255   a - b , includes one or more latching features  260  at or proximate the end portion  255   b  thereof. 
     Referring to  FIGS.  9 A and  9 B , in one or more embodiments, the cap assembly  125   b  and the centralizing insert  130   b  are assembled (e.g., toollessly and/or without fastener(s)) into the end portion  210   b  of the charge tube  120 . More particularly, the cap assembly  125   b  is inserted axially into the end portion  210   b  of the charge tube  120 , as indicated by arrow  261 , in a manner substantially identical to the manner in which the cap assembly  125   a  is inserted axially into the end portion  210   a  of the charge tube  120 , as indicated by arrow  262 , and, therefore, will not be described in further detail. Additionally, the centralizing insert  130   b  is inserted transversely through the charge tube  120 , via the slots  225   a - b , as indicated by arrow  263 , causing: the latching feature(s)  260  of the centralizing insert  130   b  to latch onto the charge tube  120  at the slot  225   b , as indicated by arrows  264 ; and the opposing end portions  255   a - b  of the centralizing insert  130   b  to each extend radially beyond the charge tube  120 . 
     Referring to  FIG.  10   , in one or more embodiments, the carrier tube  110  defines opposing end portions  265   a - b  and a central passageway  270  extending axially therethrough. Although shown as a single integrally formed body, the carrier tube  110  may instead be broken into two or more interconnected components. An orienting keyway  275  is formed internally into the carrier tube  110  at the end portion  265   a  thereof. In one or more embodiments, as in  FIG.  10   , the orienting keyway  275  extends only partway along the carrier tube  110 , thereby defining an internal shoulder  280  in the carrier tube  110  at its termination point. A plurality of scallops  285  are formed externally into the carrier tube  110 ; the plurality of scallops  285  are rotationally aligned in a 120-degree phased relationship with adjacent one(s) of the scallops  285 . Once loaded into the charge tube  120 , the perforating charges (each of which is rotationally aligned in a 120-degree phased relationship with the adjacent one(s) of the perforating charges) are adapted to be axially and rotationally aligned with respective ones of the plurality of scallops  285  formed into the carrier tube  110 , as will be described in further detail below. 
     Referring to  FIG.  11   , in one or more embodiments, the conductor sub  115  includes a sub body  290 , a conductor assembly  295  (or “feedthrough”), and a retainer  300 . The sub body  290  defines opposing end portions  305   a - b . The sub body  290  includes an enlarged-diameter portion  310  located between the end portions  305   a - b  of the sub body  290 . An external threaded connection  315   a  is formed in the sub body  290  proximate the end portion  305   a  of the sub body  290 . One or more seals are adapted to extend within one or more external annular grooves  325   a  formed into the sub body  290  between the enlarged-diameter portion  310  and the external threaded connection  315   a . Similarly, an external threaded connection  315   b  is formed in the sub body  290  proximate the end portion  305   b  of the sub body  290 . One or more seals are adapted to extend within one or more external annular grooves  325   b  formed into the sub body  290  between the enlarged-diameter portion  310  and the external threaded connection  315   b.    
     Opposing axial recesses  330   a - b  are formed into the sub body  290  at the end portions  305   a - b , respectively, of the sub body  290 . An internal bore  335  is formed through the sub body  290  between the axial recesses  330   a - b . The axial recesses  330   a - b  are substantially larger in diameter than the internal bore  335 ; as a result, an internal face  340   a  is formed in the sub body  290  where the internal bore  335  intersects the axial recess  330   a , and an internal face  340   b  is formed in the sub body  290  where the internal bore  335  intersects the axial recess  330   b . An internal threaded connection  345  is formed in the sub body  290  at the internal bore  335 , proximate the axial recess  330   a . The retainer  300  includes an external threaded connection  350  threadably engaged with the internal threaded connection  345  of the sub body  290  to retain the conductor assembly  295  within the sub body  290 . The conductor assembly  295  includes a conductor body  355  defining opposing end portions  360   a - b  disposed within the axial recesses  330   a - b , respectively, so as not to extend beyond the opposing end portions  305   a - b  of the sub body  290  when the retainer  300  retains the conductor assembly  295  within the sub body  290 . 
     In one or more embodiments, the conductor sub  115  is or includes one or more components substantially identical (or at least similar) to corresponding component(s) of the conductor sub shown and described in U.S. Application No. 63/154,626 (the “&#39;626 Application”), filed Feb. 26, 2021, the entire disclosure of which is incorporated herein by reference. For example, the conductor assembly  295  of the conductor sub  115  may be substantially identical (or at least similar) to the corresponding component(s) of the conductor sub shown and described in the &#39;626 Application. In addition, or instead, in one or more embodiments, the conductor sub  115  is or includes one or more components identical (or at least similar) to corresponding component(s) of the orienting sub shown and described in U.S. application Ser. No. 17/193,412 (the “&#39;412 Application”), filed Mar. 5, 2021, the entire disclosure of which is hereby incorporated herein by reference. For example, the conductor assembly  295  of the conductor sub  115  may be substantially identical (or at least similar) to the corresponding component(s) of the conductor sub shown and described in the &#39;412 Application. 
     Referring to  FIGS.  12 A through  12 E , in one or more embodiments, the perforating gun  100  is adapted to be assembled (e.g., toollessly and/or without fastener(s)) on-site at a wellsite before being run downhole into a wellbore and detonated to perforate the wellbore proximate a subterranean formation. When the perforating gun  100  is fully assembled: the centralizing inserts  130   a - b  each extend transversely through the charge tube  120 , as described above; the charge tube  120  is diametrically centered within the carrier tube  110  with the centralizing inserts  130   a - b  (in several embodiments, the charge tube  120  is radially centralized, or nearly radially centralized, within the carrier tube  110 , with one or both end portions  230   a - b  of the centralizing insert  130   a  contacting the inside surface of the carrier tube  110 , and with one or both end portions  255   a - b  of the centralizing insert  130   b  contacting the inside surface of the carrier tube  110 ); and the charge cartridge  105  is axially trapped between the conductor sub  115  and the internal shoulder  280  formed into the carrier tube  110  by the orienting keyway  275  (as a result, the charge cartridge  105  extends within the axial recess  330   b  formed into the sub body  290  of the conductor sub  115  at the end portion  305   b ; such extension of the charge cartridge  105  within the axial recess  330   b  formed into the sub body  290  of the conductor sub  115  at the end portion  305   b  helps to minimize, or at least decrease, the overall length L 2  of the perforating gun  100 ). In addition, or instead, the charge cartridge  105  may be trapped between the conductor sub  115  and an adjacent sub (or other component) connected at the opposing end of the perforating gun  100 ; in such instances, the charge cartridge  105  may also extend within an axial recess formed into the adjacent sub (such extension of the charge cartridge  105  within the axial recess formed into the adjacent sub helps to minimize, or at least decrease, the overall length L 2  of the perforating gun  100 ). In any case, when the perforating gun  100  is fully assembled, the charge tube  120  is not connected to the conductor sub  115 , and the perforating charges loaded in the charge tube  120  are axially and rotationally aligned with respective ones of the plurality of scallops  285  formed externally into the carrier tube  110 . 
     In one or more embodiments, the charge tube  120  defines the length L 1 , the carrier tube  110  defines a length L 3 , and a ratio of the length L 1  to the length L 3  is: equal to or greater than 0.2; equal to or greater than 0.3; equal to or greater than 0.4; equal to or greater than 0.5; equal to or greater than 0.6; equal to or greater than 0.7; equal to or greater than 0.75; equal to or greater than 0.775; equal to or greater than 0.8; equal to or greater than 0.825; equal to or greater than 0.85; equal to or greater than 0.875; equal to or greater than 0.9; or equal to or greater than 0.925. In one or more embodiments, the length L 3  of the carrier tube  110  is a maximum length of the carrier tube  110 . In some embodiments, the increased ratio of the length L 1  to the length L 3  helps to minimize, or at least decrease, the overall length L 2  of the perforating gun  100 . In several embodiments, the embodiments illustrated in the figures (including in, e.g.,  FIG.  12 B ) provide a ratio of the length L 1  of the charge tube  120  to the length L 3  of the carrier tube  110  of equal to or greater than 0.7, 0.75, 0.9, or 0.925, thereby minimizing or at least decreasing the overall length L 2  of the perforating gun  100 . 
     Referring to  FIG.  13   , in one or more embodiments the perforating gun  100  is assembled in series with one or more other perforating guns to form a gun string along which electricity is communicable to detonate the ballistic(s) of each perforating gun. 
     Referring to  FIG.  14   , in one or more embodiments, a perforating gun is generally referred to by the reference numeral  365 . The perforating gun  365  includes a charge cartridge  370 , a carrier tube  375 , and a conductor sub  380 . The charge cartridge  370  is adapted to house ballistic(s), which ballistic(s) include a singular or plurality of perforating charges and detonator cord, detonable to perforate a wellbore proximate a subterranean formation. The carrier tube  375  receives the assembled charge cartridge  370 , including the ballistic(s), a detonator, and (optionally) a switch (e.g., an addressable switch). The conductor sub  380  is adapted to: axially trap the charge cartridge  370  within the carrier tube  375 ; and conduct electricity to and/or from the charge cartridge  370  to facilitate detonation of the ballistic(s). 
     Referring to  FIG.  15   , in one or more embodiments, the charge cartridge  370  includes a charge tube  385 , cap assemblies  390   a - b , a centralizing insert  395 , and an orienting centralizer  400 . The cap assemblies  390   a - b  shown in  FIG.  15    include components and features substantially identical (or at least similar) to corresponding components and features of the cap assembly  125   a  shown and described above in connection with  FIGS.  3 A,  3 B, and  4   , and, therefore, will not be shown or described in further detail. Likewise, the centralizing insert  395  shown in  FIG.  15    is substantially identical (or at least similar) to the centralizing insert  130   b  shown and described above in connection with  FIGS.  8 A and  8 B , and, therefore, will not be shown or described in further detail below. As shown in  FIG.  15    (and  FIG.  17 A ), the charge cartridge  370  includes one or more ground conductors  405  (two are shown in the  FIGS.  15  and  17 A ), each of which is toollessly coupled (or coupled without fasteners) to at least the charge tube  385  and adapted to provide grounding electrical contact between the charge tube  385  and the carrier tube  375  when the charge tube  385  is received within the carrier tube  375 . Instead of, or in addition to, the one or more ground conductors  405  shown in  FIGS.  15  and  17 A , in a manner similar to that shown in  FIG.  2   , the cap assembly  390   a  of the charge cartridge  370  of  FIG.  15    includes another ground conductor similar to the ground conductor  205  (e.g., toollessly coupled to the cap assembly  390   a , and/or coupled to the cap assembly  390   a  without fastener(s)) and adapted to provide grounding electrical contact between the charge tube  385  and the carrier tube  375  when the charge tube  385  is received within the carrier tube  375 . 
     Referring to  FIGS.  16 A through  16 E , in one or more embodiments, the charge tube  385  defines opposing end portions  410   a - b . An access port or window  415  is formed radially through the charge tube  385  at or proximate the end portion  410   a  of the charge tube  385 , which access port or window  415  permits access to an interior of the charge tube  385  at the end portion  410   a  of the charge tube  385 , permitting insertion of a detonator on-site during assembly of the perforating gun  365  and immediately before the perforating gun  365  is deployed into a wellbore. In one or more embodiments, the access port or window  415  extends spirally (e.g., helically) along the charge tube  385 ; this spiral extension of the access port or window  415  along the charge tube  385  helps to minimize, or at least decrease, a length L 4  of the charge tube  385  and, thus, an overall length L 5  of the perforating gun  365 . In one or more embodiments, the length L 4  of the charge tube  385  is a maximum length of the charge tube  385 . Additionally, circumferentially-opposing slots  420   a - b  are formed radially through the charge tube  385  at or proximate the end portion  410   a  of the charge tube  385 , via which slots  420   a - b  the centralizing insert  395  is insertable transversely through the charge tube  385  (as shown in  FIGS.  17 A and  17 B ). When so transversely inserted through the charge tube  385 , the centralizing insert  395  is spaced inwardly from the corresponding end of the charge tube  385 . The charge tube  385  illustrated in  FIGS.  16 A through  16 E  is configured to align the perforating charges in a 180-degree phased relationship with adjacent one(s) of the perforating charges, which 180-degree phased relationship requires adjacent ones of the perforating guns to be properly circumferentially aligned with one another before being run downhole into the wellbore. This circumferential alignment is facilitated by the orienting centralizer  400 , as will be described in further detail below. 
     Referring to  FIGS.  17 A and  17 B , in one or more embodiments, the cap assembly  390   a  and the centralizing insert  395  are assembled (e.g., toollessly and/or without fastener(s)) into the end portion  410   a  of the charge tube  385 . The manner in which the cap assembly  390   a  is inserted axially into the end portion  410   a  of the charge tube  385  (as indicated by arrows  426 ,  427 ) is substantially identical (or at least similar) to the manner in which the cap assembly  125   a  is inserted axially into the end portion  210   a  of the charge tube  120 , as shown and described above in connection with  FIG.  7 A , and, therefore, will not be described in further detail. Likewise, the manner in which the centralizing insert  395  is inserted transversely through the charge tube  385 , via the slots  420   a - b  (as indicated by arrows  428 ,  429 ), is substantially identical (or at least similar) to the manner in which the centralizing insert  130   a  is inserted transversely through the charge tube  120 , via the slots  220   a - b , as shown and described above in connection with  FIGS.  7 A and  7 B , and, therefore, will not be described in further detail. In one or more embodiments, as in  FIGS.  15  and  17 A , the charge cartridge  370  further includes the pair of ground conductors  405  received (e.g., toollessly and/or without fastener(s)) within a corresponding pair of openings  425  formed through the charge tube  385 , and are adapted to provide grounding electrical contact between the charge tube  385  and the carrier tube  375  when the charge tube  385  is received within the carrier tube  375 . In one or more embodiments, the pair of ground conductors  405  are each electrically coupled to ground (e.g., one or more ground “buttons” within the perforating gun  365 ) via a quick-connect wire (e.g., enabling toolless coupling of the pair of ground conductors  405  to ground, and/or coupling of the pair of ground conductors  405  to ground without fastener(s)). 
     Referring to  FIGS.  18 A and  18 B , in one or more embodiments, the orienting centralizer  400  includes an annular body  430  defining opposing end portions  435   a - b , and a plurality of orienting keys  440  extending externally from the annular body  430  at the end portion  435   b . A pair of radial openings  445   a - b  are formed through the annular body  430 , which radial openings  445   a - b  are each adapted to receive a set screw  450  to secure the orienting centralizer  400  to the charge tube  385 , as will be described in further detail below. 
     Referring to  FIGS.  19 A and  19 B , in one or more embodiments, the conductor sub  380  includes components and features substantially identical (or at least similar) to corresponding components and features of the conductor sub  115  shown and described above in connection with  FIG.  11   , which substantially identical (or at least similar) components and features are given the same reference numerals, and will not be described in further detail. Additionally, a plurality of orienting keyways  455  are formed internally into the conductor sub  380  at the end portion  305   a  of the sub body  290  thereof. The plurality of orienting keyways  455  formed internally into the conductor sub  380  at the end portion  305   a  of the sub body  290  thereof are adapted to receive the plurality of orienting keys  440  extending externally from the orienting centralizer  400 , as will be described in further detail below. 
     In one or more embodiments, the conductor sub  380  is or includes one or more components substantially identical (or at least similar) to corresponding component(s) of the conductor sub shown and described in U.S. Application No. 63/154,626 (the “&#39;626 Application”), filed Feb. 26, 2021, the entire disclosure of which is incorporated herein by reference. For example, the conductor assembly  295  of the conductor sub  380  may be substantially identical (or at least similar) to the corresponding component(s) of the conductor sub shown and described in the &#39;626 Application. In addition, or instead, in one or more embodiments, the conductor sub  380  is or includes one or more components identical (or at least similar) to corresponding component(s) of the orienting sub shown and described in U.S. application Ser. No. 17/193,412 (the “&#39;412 Application”), filed Mar. 5, 2021, the entire disclosure of which is hereby incorporated herein by reference. For example, the conductor assembly  295  of the conductor sub  380  may be substantially identical (or at least similar) to the corresponding component(s) of the conductor sub shown and described in the &#39;412 Application. 
     Referring to  FIG.  20   , in one or more embodiments, the carrier tube  375  defines opposing end portions  460   a - b  and a central passageway  465  extending axially therethrough. A plurality of banded scallops  470  are formed externally into, and circumferentially around, the carrier tube  375 . The plurality of banded scallops  470  eliminate the need to rotationally align the perforating charges (each of which is rotationally aligned in a 180-degree phased relationship with the adjacent one(s) of the perforating charges) with respective ones of the plurality of banded scallops  470  formed externally into the carrier tube  375 , as will be described in further detail below. 
     Referring to  FIGS.  21 A through  21 G , in one or more embodiments, the perforating gun  365  is adapted to be assembled on-site at a wellsite before being run downhole into a wellbore and detonated to perforate the wellbore proximate a subterranean formation. When the perforating gun  365  is fully assembled: the centralizing insert  395  extends transversely through the charge tube  385 , as described above; the plurality of orienting keys  440  of the orienting centralizer  400  extend within the plurality of orienting keyways  455  formed into the conductor sub  380 ; the set screws  450  are received within the radial openings  445   a - b  formed through the annular body  430  of the orienting centralizer  400  to secure orienting centralizer  400  to the charge tube  385  (when so secured to the charge tube  385 , the orienting centralizer  400  is spaced inwardly from the corresponding end of the charge tube  385 ); the charge tube  385  is diametrically centered within the carrier tube  375  with the centralizing insert  395  and the orienting centralizer  400  (in several embodiments, the charge tube  385  is radially centralized, or nearly radially centralized, within the carrier tube  375 , with one or both end portions of the centralizing insert  395  contacting the inside surface of the carrier tube  375 , and with one or more peripheral portions of the orienting centralizer  400  contacting the inside surface of the carrier tube  375 ); and the charge cartridge  370  is axially trapped between the conductor sub  380  and an adjacent sub (or other component) connected at the opposing end of the perforating gun  365 . As a result, the charge cartridge  370  extends within the axial recess  330   a  formed into the sub body  290  of the conductor sub  380  at the end portion  305   a ; likewise, the charge cartridge  370  may extend within an axial recess formed into the adjacent sub. Such extension of the charge cartridge  370  within the axial recess  330   a  formed into the sub body  290  of the conductor sub  380  at the end portion  305   a  helps to minimize, or at least decrease, the overall length L 5  of the perforating gun  365 ; similarly, such extension of the charge cartridge  370  within the axial recess formed into the adjacent sub helps to minimize, or at least decrease, the overall length L 5  of the perforating gun  365 . 
     Prior to or after receiving the set screws  450  within the radial openings  445   a - b  formed through the annular body  430  of the orienting centralizer  400  to secure orienting centralizer  400  to the charge tube  385  (as shown in  FIG.  21 E ): the plurality of orienting keys  440  of the orienting centralizer  400  are received within the plurality of orienting keyways  455  formed into the conductor sub  380  (as shown in  FIG.  21 B ); the charge tube  385  is received through the orienting centralizer  400  and into the end portion  305   a  of the conductor sub  380  (as shown in  FIG.  21 C ); and the charge tube  385  is rotated freely to rotationally align the perforating charges loaded in the charge tube  385  (each of which is rotationally aligned in a 180-degree phased relationship with the adjacent one(s) of the perforating charges) as desired, for example, with one or more perforating charges in an adjacent perforating gun (as shown in  FIGS.  21 D- 1  and  21 D- 2   ). Such alignment between the shaped charges in adjacent perforating guns may be desirable, for example, in instances where the tool string also includes a weight bar to ensure proper downhole orientation of the shaped charges to perforate the wellbore at a specific angle. After receiving the set screws  450  within the radial openings  445   a - b  formed through the annular body  430  of the orienting centralizer  400  to secure orienting centralizer  400  to the charge tube  385  (as shown in  FIG.  21 E ), the carrier tube  375  is sheathed over the charge cartridge  370  and threaded to the end portion  305   a  of the conductor sub  380 ; as a result, the perforating charges loaded in the charge tube  385  are axially aligned with respective ones of the plurality of banded scallops  470  formed externally into the carrier tube  375 . 
     In one or more embodiments, the charge tube  385  defines the length L 4 , the carrier tube  375  defines a length L 6 , and a ratio of the length L 4  to the length L 6  is: equal to or greater than 0.2; equal to or greater than 0.3; equal to or greater than 0.4; equal to or greater than 0.5; equal to or greater than 0.6; equal to or greater than 0.7; equal to or greater than 0.75; equal to or greater than 0.775; equal to or greater than 0.8; equal to or greater than 0.825; equal to or greater than 0.85; equal to or greater than 0.875; equal to or greater than 0.9; or equal to or greater than 0.925. In one or more embodiments, the length L 6  of the carrier tube  375  is a maximum length of the carrier tube  375 . In several embodiments, the increased ratio of the length L 4  to the length L 6  helps to minimize, or at least decrease, the overall length L 5  of the perforating gun  365 . In several embodiments, the embodiments illustrated in the figures (including in, e.g.,  FIG.  14   ) provide a ratio of the length L 4  of the charge tube  385  to the length L 6  of the carrier tube  375  of equal to or greater than 0.7, 0.75, 0.9, or 0.925, thereby minimizing or at least decreasing the overall length L 5  of the perforating gun  365 . 
     Referring again to  FIG.  13   , in one or more embodiments the perforating gun  365  is assembled in series with one or more other perforating guns to form a gun string along which electricity is communicable to detonate the ballistic(s) of each perforating gun. 
     In several embodiments, one or more of the embodiments of the present application are provided in whole or in part as described and illustrated in the &#39;338 Application and the &#39;440 Application, each of which forms part of the present application. 
     In several embodiments, as noted above, the plurality of banded scallops  470  are formed externally into, and circumferentially around, the carrier tube  375  of  FIG.  20   ; in several embodiments, instead of, or in addition to, the carrier tube  375  of  FIG.  20   , one or more banded scallops similar to those illustrated in  FIG.  20    are formed externally into, and circumferentially around, one or more of the carrier tubes described above, illustrated in the figures, illustrated in the &#39;338 Application, illustrated in the &#39;440 Application, or any combination thereof. In several embodiments, one or more banded scallops similar to those illustrated in  FIG.  20    are formed externally into, and circumferentially around, one or more of the carrier tubes described above, illustrated in the figures, illustrated in the &#39;338 Application, illustrated in the &#39;440 Application, or any combination thereof. In several embodiments, any perforating gun that does not include an orienting centralizer, which perforating gun is described above, illustrated in the figures, illustrated in the &#39;338 Application, illustrated in the &#39;440 Application, or any combination thereof, may include banded scallops that, in some embodiments, are similar to those illustrated in  FIG.  20   . 
     In several embodiments, any charge cartridge described above, illustrated in the figures, illustrated in the &#39;338 Application, illustrated in the &#39;440 Application, or any combination thereof, includes one keyed centralizing insert and one non-keyed centralizing insert, one keyed centralizing insert and another keyed centralizing insert, or one non-keyed centralizing insert and another non-keyed centralizing insert. In several embodiments, any perforating gun that does not include an orienting centralizer, which perforating gun is described above, illustrated in the figures, illustrated in the &#39;338 Application, illustrated in the &#39;440 Application, or any combination thereof, may include one keyed centralizing insert and one non-keyed centralizing insert, one keyed centralizing insert and another keyed centralizing insert, or one non-keyed centralizing insert and another non-keyed centralizing insert. 
     In several embodiments, one or more of the embodiments described and illustrated in the &#39;440 Application are combined in whole or in part with one or more of the embodiments described above, one or more of the embodiments described and illustrated in the &#39;338 Application, and/or one or more of the other embodiments described and illustrated in the &#39;440 Application. 
     A perforating gun has been disclosed according to a first aspect, which perforating gun generally includes: a carrier tube; a charge tube extending within the carrier tube, the charge tube containing one or more perforating charges; and a conductor sub containing the charge tube within the carrier tube, the conductor sub being adapted to facilitate detonation of the one or more perforating charges; wherein the charge tube defines a first length, the first length being a maximum length of the charge tube; wherein the carrier tube defines a second length, the second length being a maximum length of the carrier tube; and wherein the perforating gun is configured so that a ratio of the first length of the charge tube to the second length of the carrier tube is greater than or equal to 0.7, thereby minimizing, or at least decreasing, an overall length of the perforating gun. In one or more embodiments, the perforating gun further includes a recess formed into the conductor sub; wherein the charge tube extends within the recess to minimize, or at least decrease, the overall length of the perforating gun. In one or more embodiments, the perforating gun further includes: an orienting centralizer including an orienting key; and an orienting keyway formed into the conductor sub; wherein the orienting key is received within the orienting keyway to prevent, or at least reduce, relative rotation between the orienting centralizer and the conductor sub. In one or more embodiments, the perforating gun further includes: one or more fasteners adapted to secure the orienting centralizer to the charge tube to prevent, or at least reduce, relative rotation between the charge tube and the orienting centralizer. In one or more embodiments, the perforating gun further includes a centralizing insert extending transversely through the charge tube; wherein the centralizing insert defines opposing first and second end portions, each of which extends radially beyond the charge tube. In one or more embodiments, the perforating gun further includes first and second circumferentially-opposing slots, each of which is formed radially through the charge tube; wherein the centralizing insert includes a latching feature at the second end portion; and wherein the latching feature is latched to the charge tube at the second slot. In one or more embodiments, the perforating gun further includes: an orienting key extending from the centralizing insert at the first end portion; and an orienting keyway formed internally into the carrier tube; wherein the orienting key is received within the orienting keyway to prevent, or at least reduce, relative rotation between the centralizing insert and the carrier tube. In one or more embodiments, the perforating gun further includes an access port or window formed radially through the charge tube proximate an end portion of the charge tube to permit insertion of a detonator into the charge tube; wherein the access port or window extends spirally along the charge tube to minimize, or at least decrease, the overall length of the perforating gun. In one or more embodiments, the perforating gun further includes a cap assembly received within an end portion of the charge tube, the cap assembly being adapted to further facilitate detonation of the one or more perforating charges. In one or more embodiments, the cap assembly includes: a conductor housing; a conductor body contained within the conductor housing; and an electrical connector toollessly coupled to the conductor body to further facilitate detonation of the one or more perforating charges. In one or more embodiments, the perforating gun further includes a ground connector toollessly coupled to the charge tube and configured to provide grounding electrical contact between the charge tube and the carrier tube. 
     A perforating gun has been disclosed according to a second aspect, which perforating gun generally includes: a carrier tube; a charge tube extending within the carrier tube, the charge tube containing one or more perforating charges; and a conductor sub containing the charge tube within the carrier tube, the conductor sub being adapted to facilitate detonation of the one or more perforating charges; wherein a recess is formed into the conductor sub; and wherein the charge tube extends within the recess. In one or more embodiments, the perforating gun further includes: an orienting centralizer including an orienting key; and an orienting keyway formed into the conductor sub; wherein the orienting key is received within the orienting keyway to prevent, or at least reduce, relative rotation between the orienting centralizer and the conductor sub. In one or more embodiments, the perforating gun further includes one or more fasteners adapted to secure the orienting centralizer to the charge tube to prevent, or at least reduce, relative rotation between the charge tube and the orienting centralizer. In one or more embodiments, the perforating gun further includes: a centralizing insert extending transversely through the charge tube; wherein the centralizing insert defines opposing first and second end portions, each of which extends radially beyond the charge tube. In one or more embodiments, the perforating gun further includes first and second circumferentially-opposing slots, each of which is formed radially through the charge tube; wherein the centralizing insert includes a latching feature at the second end portion; and wherein the latching feature is latched to the charge tube at the second slot. In one or more embodiments, the perforating gun further includes: an orienting key extending from the centralizing insert at the first end portion; and an orienting keyway formed internally into the carrier tube; wherein the orienting key is received within the orienting keyway to prevent, or at least reduce, relative rotation between the centralizing insert and the carrier tube. In one or more embodiments, the perforating gun further includes an access port or window formed radially through the charge tube proximate an end portion of the charge tube to permit insertion of a detonator into the charge tube; wherein the access port or window extends spirally along the charge tube. In one or more embodiments, the perforating gun further includes a cap assembly received within an end portion of the charge tube, the cap assembly being adapted to further facilitate detonation of the one or more perforating charges. 
     A perforating gun has been disclosed according to a third aspect, which perforating gun generally includes: a carrier tube; a charge tube extending within the carrier tube, the charge tube containing one or more perforating charges; a conductor sub containing the charge tube within the carrier tube, the conductor sub being adapted to facilitate detonation of the one or more perforating charges; and at least one centralizing insert extending transversely through the charge tube; wherein the at least one centralizing insert defines opposing first and second end portions, each of which extends radially beyond the charge tube. In one or more embodiments, the perforating gun further includes first and second circumferentially-opposing slots, each of which is formed radially through the charge tube; wherein the at least one centralizing insert includes a latching feature at the second end portion; and wherein the latching feature is latched to the charge tube at the second slot. In one or more embodiments, the perforating gun further includes: an orienting key extending from the at least one centralizing insert at the first end portion; and an orienting keyway formed internally into the carrier tube; wherein the orienting key is received within the orienting keyway to prevent, or at least reduce, relative rotation between the at least one centralizing insert and the carrier tube. In one or more embodiments, the perforating gun further includes: an orienting centralizer including an orienting key; and an orienting keyway formed into the conductor sub; wherein the orienting key is received within the orienting keyway to prevent, or at least reduce, relative rotation between the orienting centralizer and the conductor sub. In one or more embodiments, the perforating gun further includes: one or more fasteners adapted to secure the orienting centralizer to the charge tube to prevent, or at least reduce, relative rotation between the charge tube and the orienting centralizer. In one or more embodiments, the perforating gun further includes: an access port or window formed radially through the charge tube proximate an end portion of the charge tube to permit insertion of a detonator into the charge tube; wherein the access port or window extends spirally along the charge tube. In one or more embodiments, the perforating gun further includes: a cap assembly received within an end portion of the charge tube, the cap assembly being adapted to further facilitate detonation of the one or more perforating charges. 
     A perforating gun has been disclosed according to a fourth aspect, which perforating gun generally includes: a carrier tube; a charge tube extending within the carrier tube, the charge tube containing one or more perforating charges; a conductor sub containing the charge tube within the carrier tube, the conductor sub being adapted to facilitate detonation of the one or more perforating charges; an orienting centralizer including an orienting key; and an orienting keyway formed into the conductor sub; wherein the orienting key is received within the orienting keyway to prevent, or at least reduce, relative rotation between the orienting centralizer and the conductor sub. In one or more embodiments, the perforating gun further includes: one or more fasteners adapted to secure the orienting centralizer to the charge tube to prevent, or at least reduce, relative rotation between the charge tube and the orienting centralizer. In one or more embodiments, the perforating gun further includes an access port or window formed radially through the charge tube proximate an end portion of the charge tube to permit insertion of a detonator into the charge tube; wherein the access port or window extends spirally along the charge tube. In one or more embodiments, the perforating gun further includes a cap assembly received within an end portion of the charge tube, the cap assembly being adapted to further facilitate detonation of the one or more perforating charges. 
     It is understood that variations may be made in the foregoing without departing from the scope of the disclosure. 
     In several embodiments, the elements and teachings of the various illustrative embodiments may be combined in whole or in part in some or all of the illustrative embodiments. In addition, one or more of the elements and teachings of the various illustrative embodiments may be omitted, at least in part, or combined, at least in part, with one or more of the other elements and teachings of the various illustrative embodiments. 
     Any spatial references such as, for example, “upper,” “lower,” “above,” “below,” “between,” “bottom,” “vertical,” “horizontal,” “angular,” “upwards,” “downwards,” “side-to-side,” “left-to-right,” “left,” “right,” “right-to-left,” “top-to-bottom,” “bottom-to-top,” “top,” “bottom,” “bottom-up,” “top-down,” etc., are for the purpose of illustration only and do not limit the specific orientation or location of the structure described above. 
     In several embodiments, while different steps, processes, and procedures are described as appearing as distinct acts, one or more of the steps, one or more of the processes, or one or more of the procedures may also be performed in different orders, simultaneously or sequentially. In several embodiments, the steps, processes or procedures may be merged into one or more steps, processes or procedures. In several embodiments, one or more of the operational steps in each embodiment may be omitted. Moreover, in some instances, some features of the present disclosure may be employed without a corresponding use of the other features. Moreover, one or more of the embodiments disclosed above and in the &#39;338 and &#39;440 Applications, or variations thereof, may be combined in whole or in part with any one or more of the other embodiments described above and in the &#39;338 and &#39;440 Applications, or variations thereof. 
     Although several embodiments have been disclosed in detail above and in the &#39;338 and &#39;440 Applications, the embodiments disclosed are exemplary only and are not limiting, and those skilled in the art will readily appreciate that many other modifications, changes, and substitutions are possible in the embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications, changes, and substitutions are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Moreover, it is the express intention of the applicant not to invoke 35 U.S.C. § 112(f) for any limitations of any of the claims herein, except for those in which the claim expressly uses the word “means” together with an associated function.