Patent Publication Number: US-10774623-B2

Title: Perforating gun for oil and gas wells, perforating gun system, and method for producing a perforating gun

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present disclosure relates to equipment for use in a subterranean well for hydrocarbon fluid production, and in particular to a shaped charge perforating gun apparatus for generating perforations within a well casing. 
     2. Background Information 
     Subterranean wellbores are often created to provide access to a hydrocarbon bearing subterranean formation so that hydrocarbon materials may be removed from the formation. Typically, a wellbore is drilled and a hollow well casing is inserted into the well bore. The well casing increases the integrity of the wellbore and the interior passage of the well casing provides a path through which fluids from the formation may be produced to the surface. In some instances, voids between the well bore and the exterior of the well casing may be filled with a material (e.g., cement) to secure the well casing within the well bore. To permit the influx of fluids into the well casing (and removal from the well) it is necessary to create hydraulic openings or perforations through the well casing (and cement where used) to provide fluid communication between the interior passage of the well casing and the exterior geologic formation. 
     According to the prior art, the aforesaid perforations may be created by detonating a series of shaped charges located within one or more hollow body perforating guns that are deployed within the well casing at selected positions within the well bore. The shaped charges are disposed within charge holders positioned within the interior of the hollow body. The shaped charges include an explosive material and are in communication with a detonating cord. The detonating cord provides the energy necessary to detonate the shaped charges. Upon detonation the shaped charges produce explosive jets that cause penetration of the hollow body containing the shaped charges, the well casing wall (the exterior cement if used), and the adjacent formation to some degree. Prior art examples of perforating guns are disclosed in U.S. Pat. Nos. 9,238,956; 9,382,784; 9,441,438; 9,441,466; and 9,494,021. 
     In some applications, the hydrostatic pressure within the well bore/well casing during the well formation process can be enormous; e.g., in the range of about 20,000 to about 25,000 psi. Equipment used within the well bore to form the well (e.g., perforating guns) must, therefore, be designed to function in the aforesaid high pressure environment. A perforating gun for use in a seven inch (7″) diameter pipe, for example, may have a tubular hollow body with a four and three-quarters inch (4.75″) outer diameter. To accommodate the shaped charges disposed with charged holders, the interior of the hollow body must have a large inner diameter (e.g., 3.626 inches) and consequent relatively thin wall thickness. To accommodate the high hydrostatic pressures, the hollow body of such a perforating gun is typically made of a very high yield strength material (e.g., a yield strength of about 150,000 psi). Such materials are almost always quite expensive and typically available only on special order with a long lead time for delivery. 
     There are other disadvantages associated beyond the expense and lead time typically associated with the hollow body of perforating guns such as those described above and in the identified patents. For example, these type devices also utilize structures (e.g., “metal liners”) designed to hold the shaped charges. The explosive material must be packed into the metal liners at very high pressures to achieve the desired explosive performance, which is an expensive process. Furthermore, the aforesaid designs typically use a detonation cord to energize the shaped charges. Detonation cords typically include an explosive material packed within a fabric tube that can include voids when exposed to well conditions; i.e., voids that may cause the detonating cord and therefore the penetrating gun to fail. 
     SUMMARY OF THE INVENTION 
     The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosure. The summary is not an extensive overview of the disclosure. It is neither intended to identify key or critical elements of the disclosure nor to delineate the scope of the disclosure. The following summary merely presents some concepts of the disclosure in a simplified form as a prelude to the description below. 
     According to an aspect of the present disclosure, a perforating gun is provided. The perforating gun includes a body and at least one cavity liner. The body has an axial length extending between a first axial end and a second axial end, and an outer radial surface extending between the first and second axial ends, an inner bore, and at least one shaped charge cavity disposed in the outer radial surface. The at least one shaped charge cavity is in fluid communication with the inner bore. The at least one cavity liner is disposed in the shaped charge cavity and is configured to retain an explosive material within the shaped charge cavity. 
     According to another aspect of the present disclosure a perforating gun system is provided that includes a plurality of perforating gun sections, with each section connected to at least one other perforating gun section. Each perforating gun section includes a body and at least one cavity liner. The body has an axial length extending between a first axial end and a second axial end, and an outer radial surface extending between the first and second axial ends, an inner bore, and at least one shaped charge cavity disposed in the outer radial surface. The at least one shaped charge cavity is in fluid communication with the inner bore. The at least one cavity liner is disposed in the shaped charge cavity and is configured to retain an explosive material within the shaped charge cavity. 
     In any of the above aspects, the perforating gun body may include at least one inner bore fluid escape port in communication with the inner bore, which inner bore fluid escape port extends from the inner bore to an exterior of the body. 
     In any of the above aspects and embodiments, the inner bore may extend between and be in fluid communication with the first axial end and the second axial end. 
     In any of the above aspects and embodiments, the perforating gun body may further include at least one cavity fluid escape port in communication with each shaped charge cavity, which cavity fluid escape port extends from the respective shaped charge cavity to an exterior of the body. 
     In any of the above aspects and embodiments, the perforating gun may further include an explosive material disposed within the inner bore and within the at least one shaped charge cavity. 
     In any of the above aspects and embodiments, the inner bore has a diameter and the body has an outer diameter, and a ratio of the outer diameter of the body to diameter of the inner bore may be in the range of about 7:1 to about 19:1. 
     According to another aspect of the present disclosure, a method of producing a perforating gun is provided. The method includes: a) providing a perforating gun body having an axial length extending between a first axial end and a second axial end, and an outer radial surface extending between the first and second axial ends, an inner bore, and a plurality of shaped charge cavities disposed in the outer radial surface, wherein the shaped charge cavities are in fluid communication with the inner bore, and at least one inner bore escape port extending from the inner bore to an exterior of the body, and at least one cavity fluid escape port in communication with a respective one of the plurality of shaped charge cavities, which cavity fluid escape port extends from the respective one of the shaped charge cavities to the exterior of the body; b) inserting a cavity liner into each shaped charge cavity, which cavity liner is configured to retain an explosive material within the shaped charge cavity; and c) filling the inner bore and the plurality of shaped charge cavities with an explosive material. 
     In some embodiments of the above aspect, the perforating gun the inner bore extends between and is in fluid communication with the first axial end and the second axial end, and a first plug is disposed within inner bore proximate the first axial end and a second plug is disposed within inner bore proximate the first axial end, and the step of filling includes inserting explosive material includes filling the body until explosive material is visible in, or exits from, the at least one inner bore fluid escape port and each of the cavity fluid escape ports. 
     In any of the above aspect and embodiments, the inner bore has a diameter and the body has an outer diameter, and a ratio of the outer diameter of the body to diameter of the inner bore may be in the range of about 7:1 to about 19:1. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. The drawing figures are not necessarily drawn to scale unless specifically indicated otherwise. 
         FIG. 1  illustrates a perforating gun section embodiment according to the present disclosure. 
         FIG. 2  illustrates a perforating gun section embodiment according to the present disclosure. 
         FIG. 3  illustrates a perforating gun embodiment according to the present disclosure, including two sections coupled together. 
         FIG. 4  is a diagrammatic partial sectional view of a perforating gun body embodiment, showing a shaped charge cavity in communication with the inner bore. 
         FIG. 5  is a diagrammatic view of a perforating gun section having a shaped charge cavity pattern. 
         FIG. 6  is a diagrammatic view of a compaction device. 
         FIG. 7  is a block diagram illustrating a method for producing embodiments of the present perforating gun. 
     
    
    
     DETAILED DESCRIPTION 
     It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities or a space/gap between the entities that are being coupled to one another. 
     Referring to  FIGS. 1-3 , an embodiment of a perforating gun  10  is shown relative to the wellbore casing  12 . The perforating gun  10  embodiment shown includes a first section  10 A (See  FIGS. 1 and 3 ) coupled with a second section  10 B (See  FIGS. 2 and 3 ). The perforating gun  10  may comprise only a single section, or may comprise two or more sections. The aforesaid sections may be coupled to one another in a variety of different ways; e.g., by screw thread, mechanical fastener, etc. In the embodiment shown the first and second sections have the same configurations. The present disclosure is not, however limited to this embodiment; e.g., different sections of the perforating gun  10  may be configured differently. 
     Each section of the assembled perforating gun  10  includes a body  14 , explosive material  16 , and a plurality of shaped charge cavity liners  18 .  FIG. 1  shows perforating gun section  10 A as including explosive material  16 , and  FIG. 2  shows perforating gun section  10 B without explosive material  16  to illustrate that a perforating gun  10  may be manufactured and shipped without explosive material  16  and the explosive material  16  subsequently added. In some embodiments, each perforating gun section further includes one or more explosive boosters  20  and compaction devices  22 . The body  14  of each perforating gun section has an outer diameter  24 , an outer radial surface  26 , an inner bore  28 , and a length  30 . The outer diameter  24  extends radially (e.g., along a “Y” axis in the orthogonal axes shown in  FIGS. 1 and 2 ) between opposing outer radial surfaces  26 . The length  30  extends axially (e.g., along a “X” axis in the orthogonal axes shown in  FIGS. 1 and 2 ) between a first axial end surface  32  and an opposing second axial end surface  34 . The perforating gun  10  embodiment shown in  FIGS. 1-3  is depicted as being cylindrical, but the present disclosure is not limited to a cylindrically shaped perforating gun  10 . 
     Each perforating gun section may be initially formed with an inner bore  28 , or the inner bore  28  may be formed within a solid body; e.g., by machining, etc. The inner bore  28  has a diameter  36  that is small relative to the outer diameter  24  of the body  14 . For example, a body  14  having an outer diameter  24  in the range of about four to seven inches (4.0-7.0″) may have an inner bore diameter  36  of about 0.3-0.4 inches. The specific inner bore diameter  36  and body outer diameter  24  can be varied to suit a number of different applications; e.g., the dimensions of the body  14  may be varied to suit the well casing inner diameter, etc. In most applications, the body  14  has an outer diameter  24  to inner bore diameter  36  ratio in the range of about 7:1 to about 19:1. In most applications, the inner bore diameter is preferably at least about 0.3 inches. The inner bore  28  extends between the first axial end surface  32  and the second axial end surface  34 ; e.g., a distance from one of the axial end surfaces that is sufficient so the inner bore  28  can connect with each shaped charge cavity  38 . In the embodiment shown in  FIGS. 1 and 2 , the inner bore  28  extends from the first axial end surface  32  to the second axial end surface  34 , thereby providing an internal passage through the entirety of each perforating gun section. 
     The perforating gun section body  14  includes a fluid (e.g., air) escape port  40  in communication with the inner bore  28  (which fluid escape port may be referred to as an “inner bore fluid escape port  40 ”). In preferred embodiments, a fluid escape port  40  is disposed proximate each axial end of the inner bore  28 . Each fluid escape port  40  extends from the inner bore  28  to an outer surface of the body  14 , thereby establishing a fluid passage between the inner bore  28  and the outer surface in the absence of a material blocking the air escape port  40 . In the example shown in  FIGS. 1 and 2 , each penetrating gun section includes a fluid escape port  40  that extends from the inner bore  28  to an axial end surface  32 ,  34  of the body  14 . Each fluid escape port  40  intersects with the inner bore  28  an axial distance away from the respective axial end surface  32 ,  34  to penult the inclusion of an explosive booster  20  (discussed below) disposed within inner bore  28  at the respective axial end surface  32 ,  34 . 
     The body  14  may be made from a variety of different materials, and therefore is not limited to any particular material. An acceptable material is, for example, a K-55 steel that has a yield strength of 55,000 psi. In some embodiments, the body  14  (and/or parts of the perforating gun  10 ) may be made of a material that will erode or dissolve in a well environment; e.g., a material that will react (e.g., dissolve or erode) in the presence of materials typically found within a well environment. As a result, the need to remove a perforating gun  10  subsequent to operation of the gun may be diminished or eliminated. An example of a material that may be used to form the perforating gun body  14  and/or parts of the perforating gun  10  that dissolves or erodes is zinc or a zinc alloy material. 
     The body  14  includes a plurality of shaped charge cavities  38  disposed in the outer radial surface  26  of the body  14 . Each of the shaped charge cavities  38  disposed within the body  14  may have the same geometry, or the plurality of shaped charge cavities  38  may include different geometries. The present disclosure is not limited to any particular shaped charge cavity  38  geometry.  FIG. 4  illustrates a diagrammatic view of a shaped charge cavity  38  in communication with the inner bore  28 . Each shaped charge cavity  38  is defined by one or more lateral surfaces  42 , an outer radial end  44 , and a base end  46 . The outer radial end  44  is open to allow access into the cavity  38 . The one or more lateral surfaces  42  extend between the outer radial end  44  (which outer radial end  44  is disposed at a plane co-planar with the outer radial surface  26 ) to the base end  46 . The radial depth  48  of each shaped charge cavity  38  extends along a radial line extending from the base end  46  to the outer radial end  44 . The base end  46  of each shaped charge cavity  38  intersects with the inner bore  28  and creates a fluid passage between the respective shaped charge cavity  38  and the inner bore  28 . The volume(s) of the shaped charge cavities  38  is chosen so that an adequate amount of explosive material can be held within the shaped charge cavity  38  as will be described below. Each shaped charge cavity  38  is fluidically connected to the outer radial surface  26  of the body  14  by one or more fluid (e.g., air) escape ports  50  (which may be referred to as “cavity fluid escape ports  50 ”). Preferably, the fluid escape port(s)  50  intersect a lateral surface  42  of the respective shaped charge cavity  38  proximate the shaped charge cavity liner  18  as will be discussed below. 
     The plurality of shaped charge cavities  38  may be positioned at a variety of axial and circumferential positions (sometimes referred to as “phasing”); e.g., chosen to satisfy the specific application at hand. The axial spacing of the shaped charge cavities  38  may be uniform (e.g., a shaped charge cavity  38  every “A” distance), or may be non-uniform. The circumferential spacing of the shaped charge cavities  38  may be uniform (e.g., a shaped charge cavity  38  every “90” degrees), or may be non-uniform.  FIG. 5  diagrammatically illustrates a body  14  configuration where the outer radial surface  26  of body  14  is shown in a planar manner (i.e., the outer surface is “unrolled”) so the relative position of the shaped charge cavities  38  can be seen in a single view. In this example, the shaped charge cavities  38  are uniformly separated every “A” distance in the axial direction, and are uniformly separated every “90” degrees circumferentially. In this exemplary configuration, therefore, the shaped charge cavities  38  are positioned along a line that spirals around the circumference of the body  14 . The present disclosure is not limited to this embodiment. The diagrammatic view shown in  FIGS. 1 and 2 , for example, shows shaped charge cavities  38  disposed radially across from one another. 
     In some embodiments, the body  14  includes at least one fill port  52  that extends from the inner bore  28  to the outer radial surface  26  of the body  14 , providing a fluid passage through which an explosive material  16  can be passed from the exterior of the penetrating gun section into the inner bore  28  and shaped charge cavities  38 . The fill port  52  may be configured to receive a one-way pressure relief valve  54  that allows a pressurized fluid (e.g., a gas) to escape from the inner bore  28  to the exterior of the penetrating gun. The one-way pressure valve  54  is configured to prevent ingress of well materials disposed around the penetrating gun  10  into the inner bore  28  under well hydrostatic pressures. 
     A variety of different explosive materials  16  can be used with the present disclosure and the present disclosure is not, therefore, limited to any particular explosive material. Acceptable examples of explosive materials  16  include, but are not limited to, Cyclotrimethylenetrinitramine, C3H6N606 (sometimes referred to as “Royal Demolition Explosive” or “RDX”), cyclotetramethylene-tetranitramine (sometimes referred to as “High Melting Explosive” or “HMX”), Hexanitrostilbene (sometimes referred to as “HNS” or “JD-X”), and 2,6-Bis(Picrylamino)-3,5-dinitropyridine (sometimes referred to as “PYX”) Preferably, the explosive material  16  is in a form that can be wetted (e.g., into a fluid form such as a slurry having material properties that allows the wetted explosive material  16  to pass through the fill port  52 , through the inner bore  28 , into the plurality of shaped charge cavities  38 , and into the respective air escape ports  40 ,  50 , as will be explained below). A variety of different carrier materials (e.g., water) can be used to “wet” the explosive material, and the present disclosure is therefore not limited to any particular carrier material. Preferably, however, the carrier material is one that can be readily removed from the explosive material  16 ; e.g., by exposure to an elevated temperature and/or pressure as described below. 
     Each of the shaped charge cavity liners  18  is configured to mate with a respective shaped charge cavity  38 . Each cavity liner  18  is configured to retain explosive material  16  within a shaped charge cavity  38  in which it is installed. The cavity liner  18  may also form a seal that prevents well materials from contacting the explosive material  16 . The present disclosure is not limited to any particular cavity liner  18  configuration. The cavity liners  18  shown in  FIGS. 1 and 2 , for example are configured as concave shaped disks (e.g., conical, parti-spherical, parabolic, etc.), with the “peak” of the disk pointing toward the base end  46  of the shaped charge cavity  38 . Each cavity liner  18  may be disposed within the shaped charge cavity  38  in contact with the one or more lateral surfaces  42  of the shaped charge cavity  38 . Alternatively (as shown in  FIGS. 1 and 2 ), a cavity liner  18  may be received within a shallow bore that surrounds the shaped charge cavity  38  at the outer radial end  44 . The cavity liners  18  may be held in place by a variety of different mechanisms (e.g., a press fit, a mechanical retainer, an adhesive, weld, solder, screw thread, etc.) and the present disclosure is not limited to any particular mechanism for securing the cavity liner  18 .  FIGS. 1 and 2  show liner retaining rings  56  that are used to hold the cavity liners  18  in place. Examples of cavity liner  18  materials include, but are not limited to, copper, brass, steel, and Inconel. 
     As indicated above, in some embodiments each perforating gun section further includes one or more explosive boosters  20 . The one or more explosive boosters  20  may be disposed within the inner bore  28 . The perforating gun section embodiments shown in  FIGS. 1 and 2 , for example, include explosive boosters  20  disposed in the inner bore  28  proximate each axial end surface  32 ,  34  of the perforating gun section. The explosive boosters  20  are inserted into the inner bore  28  in a manner so they “plug” the inner bore  28  and form a seal. The seal created by the explosive booster  20  prevents ingress of well materials into the inner bore, and prevents explosive material from escaping the inner bore  28  during manufacture of the perforating gun section as described below. The explosive boosters  20  are also configured to create a “stop-fire”, in the event an upper penetrating gun section fails to detonate properly. For example, in a perforating gun system that includes a plurality of sections the explosive boosters  20  may be configured to transfer sufficient energy from one perforating gun section to initiate an explosive booster  20  in an adjacent, subsequent perforating gun section under normal conditions. In the event the perforating gun system is compromised between sections (e.g., water fouled), the explosive booster  20  will typically not provide sufficient energy to initiate the subsequent gun section, thereby creating a “stop-fire”. The present disclosure is not limited to any particular type of explosive booster  20 . Examples of acceptable explosive boosters  20  include structures that include explosive materials such as, but not limited to RDX, HMX, HNS, or PYX. 
     In some embodiments, each perforation gun section includes one or more compaction devices  22 . The present disclosure is not limited to any particular compaction device  22  configuration, other than one that can assist in increasing the compaction of the explosive material  16  within the body  14  of the perforating gun  10  section.  FIG. 5 , for example, diagrammatically shows a compaction device  22  embodiment that includes a sliding piston  58  that is translatable within a body  60  along an axis but is preferable restrained from exiting the device  22  (at least at one end). As will be explained below, a compaction device  22  may be installed within the outer radial surface  26  of the section body  14 . The compaction device  22  may be installed so that the sliding piston  58  is initially disposed toward the outer radial surface  26  of the body  14 , or the sliding piston  58  may be translated outwardly toward the outer radial surface  26  during installation of the explosive material  16 . During operation when the perforating gun  10  is exposed to hydrostatic pressure within the wellbore casing  12 , the sliding piston  58  may be forced inwardly (e.g., radially inwardly). As a result of the piston  58  translating inwardly, the compaction device  22  decreases the volume assumed by the explosive material  16  and thereby increases the compaction of the explosive material  16  within the perforation gun  10  section. 
     In some embodiments, a perforating gun  10  according to the present disclosure may also include one or more pressure barriers  62  disposed with respective shaped charge cavities  38 . The present disclosure is not limited to any particular pressure barrier  62  configuration. The pressure barriers  62  shown in  FIG. 2 , for example are configured as flat or shaped disks (e.g., conical, parti-spherical, parabolic, etc.), with the “peak” of the pressure barrier  62  pointing away from the cavity liner  18  and the shaped charge cavity  38 . The pressure barrier  62  may be disposed within the shaped charge cavity  38  in contact with the one or more lateral surfaces  42  of the shaped charge cavity  38 , or may be in contact with the cavity liner  18 , or in contact with a retainer ring  56 , or any combination thereof. The pressure barriers  62  may be held in place by a variety of different mechanisms (e.g., a press fit, a mechanical retainer, an adhesive, weld, solder, screw thread, etc.) and the present disclosure is not limited to any particular mechanism. The pressure barriers  62  provide a degree of stand-off/isolation of the shaped charge (i.e., the explosive material  16  disposed within the shaped charge cavity  38 ) before the shaped charge encounters any fluid, which may improve jet performance of the shaped charge. The pressure barriers  62  may also help to protect against fluid ingress into the respective shaped charge cavity  38 . Some pressure barriers  62  may be described and function as thin rupture disk membranes. 
     Referring to  FIGS. 1-7 , during manufacture of the body  14  of each perforating gun  10  section, the body is formed (e.g., by machining, casting, additive manufacturing, etc.) to include the outer radial surface  26 , the inner bore  28 , and the one or more shaped charge cavities  38 . Typically, the body  14  is also formed to include at least one inner bore fluid escape port  40  in communication with the inner bore  28  and at least cavity fluid escape port  50  in communication with each shaped charge cavity  38 , and at least one fill port  52 . In the embodiments shown in  FIGS. 1 and 2 , the perforating gun section bodies  14  are also formed to receive a compaction device  22 . 
     Subsequent to the body  14  being formed, the one or more explosive boosters  20  and the cavity liners  18  are installed. For example, in the perforating gun  10  section embodiment shown in  FIGS. 1 and 2 , an explosive booster  20  is installed at each end of the inner bore  28 , and a cavity liner  18  and a liner retaining ring  56  is inserted in each shaped charge cavity  38 . In the perforating gun  10  embodiment shown in  FIG. 2 , a pressure barrier  62  is also installed in each shaped charge cavity  38 . Also in the embodiments shown in  FIGS. 1 and 2 , a compaction device  22  is installed in each perforating gun section body  14 . 
     At this point in the assembly of each perforating gun  10 , a cavity fluid escape port  50  fluidly connects each shaped charge cavity  38  with the inner bore  28 , and with the exterior of the body  14 . In addition, the inner bore  28  is in fluid communication with the exterior of body  15  via the inner bore fluid escape ports  40  and the fill port  52 . 
     Explosive material is introduced into the inner bore  28  through the fill port  52 . As indicated above, the explosive material  16  is preferably in a wetted form to facilitate flow of the explosive material  16  through the inner bore  28 , into the plurality of shaped charge cavities  38 , and into the respective fluid escape ports  40 ,  50 . The wetted form of the explosive material  16  also makes it easier to create a relatively compacted form of the explosive material  16  within the various voids. The insertion of the explosive material  16  preferably continues until explosive material  16  escapes from all of the respective fluid escape ports  40 ,  50 . During the insertion of the explosive material  16 , any air that is present within the body  14  exits the body  14  via a fluid escape port  40 ,  50 . Hence, all voids within the body  14  are filled with explosive material  16 ; i.e., the entire inner bore  28  from explosive booster  20  to explosive booster  20 , the associated fluid escape ports  40 ,  50 , and all of the shaped charge cavities  38  are filled with explosive material  16 . In those embodiments having a compaction device  22 , the compaction device  22  may also be filled with explosive material  16 . In some instances, it may be desirable to block certain of the fluid escape ports  40 ,  50  during the insertion process to ensure the desired flow and insertion of explosive material  16  throughout the body  14 . 
     After the body cavities  28 ,  38  and ports  40 ,  50  are filled with explosive material  16 , some amount of explosive material  16  is removed from the respective fluid escape ports  40 ,  50  to permit the insertion of a seal material  64  into the respective fluid escape port  40 ,  50 . The seal material  64  prevents well materials from entering the fluid escape ports  40 ,  50  and potentially fouling the explosive material  16 . 
     Once the explosive material  16  is completely inserted into the body  14 , a one-way pressure relief valve  54  may be installed into the fill port  52 . 
     As stated above, a perforating gun  10  according to the present disclosure may comprise a single perforating gun  10  section or a plurality of perforating gun  10  sections to suit the application at hand. For those applications where it is desirable to use more than one perforating gun  10  section, the sections (e.g.,  10 A,  10 B) can be combined together to create the desired length and performance perforating gun  10 . 
     During operation, as the perforating gun  10  is inserted into a wellbore casing  12  it will likely be exposed to increasing higher temperatures and pressures. The high temperature outside of the perforating gun  10  (when disposed within the well casing) also increases the temperature of the explosive material  16  within the body  14 . As a result, any remaining carrier fluid (e.g., water) may escape the interior of the body  14  via the one-way pressure valve  54 . In addition, the environmental pressure may also act on the explosive material  16  disposed within the body  14 . For example, the pressure may cause a portion of the compaction device  22  (e.g., the piston) to move inwardly, thereby increasing the compaction of the explosive material  16 . In addition in those embodiments that do not include pressure barriers  62  disposed within the shaped charge cavities  38 , the cavity liners  18  may also move radially inwardly to increase the compaction of the explosive material  16  within the respective shaped charge cavities  38 . Hence, the explosive material  16  is compressed to a degree of compaction (which may be referred to as a degree of density of the collective material) that is favorable for detonation of the explosive material  16 . 
     A perforating gun section or system according to the present disclosure may be utilized with a variety of different systems for initiating a section (or sections of a system), and therefore is not limited to use with any particular initiating system. Initiating systems may include, for example, an electrical or electronic detonator that is used to fire into a first “top” explosive booster  20  (e.g., connected to the surface by a communications line), or by a mechanically actuated (TCP-type) initiator that fires into the top explosive booster  20 , etc. Typically, once the top explosive booster is initiated, the perforating gun sections are initiated sequentially in a manner described above. 
     Technical effects and benefits of this disclosure include a perforating gun  10  that is manufactured of commercially available, off-the-shelf materials. Aspects of the disclosure may be used to increase the efficiency of a perforating gun  10  (illustratively measured in terms of detonation energy per unit length/area) while at the same time increasing/maximizing the reliability of the perforating gun  10 . The manufacture of the perforating gun  10  may be simplified as the number/count of the discrete components that are used may be reduced/minimized relative to a conventional perforating gun  10 . For example, whereas in conventional perforating guns the detonating cord and the shaped charges are separate components from a carrier body, in accordance with aspects of this disclosure the inner bore  28  and the shaped charge cavities  38  are formed in the body itself thereby eliminating the need for a detonating cord and independent liners for holding the shaped charges. 
     Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional in accordance with aspects of the disclosure. One or more features described in connection with a first embodiment may be combined with one or more features of one or more additional embodiments.