Encapsulated shaped charge

Abstract

Various exemplary embodiments of an encapsulated shaped charge (100) may include a charge case (110), a charge lid (120) covering an open end of the charge case, and an external clip assembly connected to each of the charge case and the charge lid. The charge case may house explosive material (111) and a shaped charge liner (112). The external clip assembly may include one or more clips (140) respectively connected to each of a retainer ring (130) positioned on the charge lid, and the charge case. The retainer ring may be formed from a material that will melt or burn when exposed to fire. According to the exemplary embodiments, melting or burning the retainer ring can release the one or more clips from the retainer ring and/or charge lid.

Description

BACKGROUND OF THE DISCLOSURE

Oil and gas well completion processes include perforating a hydrocarbon formation to liberate the oil and gas within reservoirs therein. Hydrocarbon formations may include, for example, subterranean oil and gas shale formations, sandstone formations, and/or carbonate formations. Perforating guns perform the perforating operations. The perforating guns carry explosive charges, i.e., “shaped charges”, into a wellbore that has been drilled into the hydrocarbon formation. The shaped charges detonate and an explosive jet formed by each shaped charge may perforate one or more of a structure surrounding the shaped charge or perforating gun within the wellbore, a layer of cement surrounding the wellbore, and the hydrocarbon formation. For example, the wellbore may include cemented-in casing pipes and other tubulars (collectively, “wellbore casing”) that isolate an environment within the wellbore from the hydrocarbon formation prior to perforating. For brevity within this disclosure, the term “wellbore” refers to the drilled wellbore and any wellbore casing therein, except where otherwise specified.

The shape and configuration of the shaped charge and resulting explosive jet may vary depending on operational requirements. For example, abandonment procedures for decommissioned wells include permanently sealing the wellbore using cement. Unwanted vertical channels or voids may exist in a previously cemented wellbore annulus between the wellbore casing and the hydrocarbon formation may produce migration pathways for fluids or gas to contaminate surrounding areas. A “cement squeeze” operation uses perforating guns to perforate through the wellbore casing, but not necessarily into the hydrocarbon formation, to access the wellbore annulus via perforations through which cement is squeezed, under pressure, into the wellbore annulus. A goal for cement squeeze operations is for perforations to provide 360-degree access from within the wellbore casing to the wellbore annulus, to increase the coverage of cement in the annulus. Accordingly, a conventional perforating gun for a cement squeeze operation may include a helical arrangement of overlapping “slotted” shaped charges (FIG. 20) that are rectangularly-shaped and produce rectangularly-shaped perforations. The rectangular shape allows the long portions of the rectangular perforations to overlap and thereby provide 360-degree access.

The wellbore casing may also be a conduit for a wellbore fluid that is pumped into the wellbore casing to “pump down” perforating guns and reduce the time required for the perforating guns to reach their positions. The shaped charges must be sealed and protected against the wellbore fluids and hydraulic pressures within the wellbore. For example, in a typical “gun carrier”-type perforating gun, the shaped charges are retained and oriented in a charge carrier, such as a metal tube, housed with other perforating gun components within a sealed interior chamber of, e.g., a cylindrical gun housing such as a metal tube. Components within the sealed interior chamber need not be individually protected, but the shaped charge explosive jets must penetrate the gun housing in addition to, e.g., the wellbore casing. Alternatively, a typical “exposed” perforating gun includes shaped charges retained and oriented in a charge carrier that is exposed to the wellbore environment. The shaped charges must be individually protected against the wellbore environment, but the explosive jets need not first penetrate a gun housing, nor is the extra material, weight, machining, or cost a gun housing required. The shaped charges are typically protected by, among other things, sealing the interior of the shaped charges, including the explosive components, with a charge lid that covers and seal an open end of the shaped charge. The charge lid protects the components during normal use, but the sealed interior may present safety risks if, for example, the sealed charge is exposed to fire and the heat therefrom causes a buildup of gas pressure from the explosive within.

For at least the above reasons, a need exists for an encapsulated shaped charge that provides both a strong seal for the charge and safety.

BRIEF DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

In an aspect, the disclosure relates to an encapsulated shaped charge. The encapsulated shaped charge may include a charge case and a charge lid. The charge case may hold an explosive and a liner. The charge lid may cover an open end of the charge case. The encapsulated shaped charge may further include an external clip assembly connected to each of the charge case and the charge lid.

In an aspect, the disclosure relates to an exposed perforating gun system. The exposed perforating gun system may include a charge carrier retaining a plurality of encapsulated shaped charges. Each shaped charge may include a charge case holding an explosive and a liner, a charge lid covering an open end of the charge case, and an external clip assembly. The external clip assembly may be connected to each of the charge case and the charge lid.

In an aspect, the disclosure relates to a method for reducing a buildup of gas pressure in an encapsulated shaped charge exposed to fire. The method may include enclosing an explosive within a charge case by, e.g., positioning a charge lid on an open end of the charge case within which the explosive is contained. The method may further include releasably connecting the charge lid to the charge case. Releasably connecting the charge lid to the charge case may include positioning a retainer ring on the charge lid and connecting a first end of a clip to the retainer ring and a second end of the clip to a bottom surface of the charge case. The retainer ring may be configured to melt or burn in response to exposure to fire. The method may further include releasing the clip from encapsulated shaped charge, in response to the retainer ring melting or burning in response to exposure to fire.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description will be rendered by reference to exemplary embodiments that are illustrated in the accompanying figures. Understanding that these drawings depict exemplary embodiments and do not limit the scope of this disclosure, the exemplary embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 is a partial cross-sectional view of an encapsulated shaped charge, according to an exemplary embodiment;

FIG. 2A is a perspective view of an encapsulated shaped charge, according to an exemplary embodiment;

FIG. 2B is a front view of an encapsulated shaped charge, according to an exemplary embodiment, rotated 90-degrees;

FIG. 3 is a top perspective view of the encapsulated shaped charge of FIG. 1, according to an exemplary embodiment;

FIG. 4 is a top perspective view of a charge case, according to an exemplary embodiment;

FIG. 5 is a bottom perspective view of the encapsulated shaped charge of FIG. 1, according to an exemplary embodiment;

FIG. 6 is a bottom perspective view of a charge case, according to an exemplary embodiment;

FIG. 7 shows a clip, according to an exemplary embodiment;

FIG. 8 shows a retainer ring, according to an exemplary embodiment;

FIG. 9 is a top perspective view of a charge lid, according to an exemplary embodiment;

FIG. 10A is a bottom perspective view of a charge lid, according to an exemplary embodiment;

FIG. 10B is an enlarged view of the charge lid of FIG. 10A, according to an exemplary embodiment;

FIG. 11 shows an o-ring seal, according to an exemplary embodiment;

FIG. 12 is an enlarged view of the charge lid of FIG. 9, according to an exemplary embodiment;

FIG. 13 is an enlarged view of the retainer ring shown in FIG. 8, according to an exemplary embodiment;

FIG. 14 is an enlarged view of the clip shown in FIG. 7, according to an exemplary embodiment;

FIG. 15 is a front, bottom perspective view of a charge case, according to an exemplary embodiment;

FIG. 16A shows an external clip assembly, according to an exemplary embodiment;

FIG. 16B shows an encapsulated conical shaped charge, according to an exemplary embodiment;

FIG. 17A shows an encapsulated conical shaped charge, according to an exemplary embodiment;

FIG. 17B shows an external clip assembly, according to an exemplary embodiment;

FIG. 18A shows an external clip assembly, according to an exemplary embodiment;

FIG. 18B shows an encapsulated conical shaped charge, according to an exemplary embodiment;

FIG. 19A shows an encapsulated conical shaped charge, according to an exemplary embodiment;

FIG. 19B shows an external clip assembly, according to an exemplary embodiment;

FIG. 20 shows an exposed perforating gun system, according to an exemplary embodiment;

FIG. 21 is a front, top perspective view of an encapsulated shaped charge, according to an exemplary embodiment;

FIG. 22 is a top perspective view of the encapsulated shaped charge of FIG. 21, according to an exemplary embodiment;

FIG. 23 is a partial cross-sectional view of an encapsulated shaped charge, according to an exemplary embodiment;

FIG. 24 is a front, top perspective view of a charge lid, according to an exemplary embodiment;

FIG. 25 is a bottom perspective view of a charge lid, according to an exemplary embodiment; and

FIG. 26 is a cross-sectional view of a charge lid, according to an exemplary embodiment.

Various features, aspects, and advantages of the exemplary embodiments will become more apparent from the following detailed description, along with the accompanying drawings in which like numerals represent like components throughout the figures and detailed description. The various described features are not necessarily drawn to scale in the drawings but are drawn to aid in understanding the features of the exemplary embodiments.

The headings used herein are for organizational purposes only and are not meant to limit the scope of the disclosure or the claims. To facilitate understanding, reference numerals have been used, where possible, to designate like elements common to the figures.

DETAILED DESCRIPTION

Reference will now be made in detail to various exemplary embodiments. Each of the exemplary embodiments is illustrative, provided by way of explanation, and not limiting. The exemplary embodiments do not constitute a definition of all possible embodiments. It is understood that reference to a particular “exemplary embodiment” of, e.g., a structure, assembly, component, configuration, method, etc. includes exemplary embodiments of, e.g., the associated features, subcomponents, method steps, etc. forming a part of the “exemplary embodiment”.

For purposes of this disclosure, the phrases “devices,” “systems,” and “methods” may be used either individually or in any combination referring without limitation to disclosed components, grouping, arrangements, steps, functions, or processes.

With reference to FIGS. 1-6, the exemplary embodiments relate to an encapsulated shaped charge 100 for use in, without limitation, an exposed perforating gun system 200 (FIG. 20). The exemplary encapsulated shaped charge 100 shown in FIGS. 1-6 is a slotted shaped charge. In other words, it is generally rectangularly shaped. The exemplary encapsulated shaped charge includes a charge case 110 holding an explosive 111 and a liner 112 as are known for shaped charges. The charge case 110 includes a base wall 110c, opposing face walls 110a in a spaced apart relationship, and opposing side walls 110b in a spaced apart relationship. Each of the face walls 110a and the side walls 110b extends upwardly from the base wall 110c. Each of the side walls 110b extends from one of the face walls 110a to the opposing face wall 110a. The base wall 110c, opposing face walls 110a, and side walls 110b together define a charge case interior 116. The explosive 111 and the liner 112 are positioned within the charge case interior 116.

A charge lid 120 covers and seals an open end 117 opposite the base wall 110c of the charge case 110 (thereby making the shaped charge “encapsulated”). The charge lid 120 seals the encapsulated shaped charge 100 with, for example, an o-ring 150 (FIG. 11) positioned between the charge lid 120 and the charge case 110 and fixed within a channel 125 formed in the charge lid 120. The o-ring 150 may be in sealing contact with the charge lid 120, i.e., the channel 125, and the charge case 110. An inner skirt 121 extends downward from an inside portion 122 of the charge lid 120, such that the inner skirt 121 extends through the open end 117 of the charge case 110 and is adjacent a portion of the charge case 110 at the open end 117. The inner skirt 121 may provide additional stability of the charge lid 120 in position above the open end 117.

The exemplary embodiment shown in FIGS. 1-3 and 5 further includes a fastening assembly 160 for holding the charge lid 120 on the charge case 110. In the exemplary embodiments, but not limited thereto, the fastening assembly 160 includes a retainer ring 130 extending around a peripheral shoulder 127 (FIG. 9) of the charge lid 120 and opposing clips 140 on opposite sides of the encapsulated shaped charge 100. The opposing clips 140, individually or together, form an external clip assembly. In other words, for purposes of this disclosure, “external clip assembly” may refer to one or more clips 140 configured on an exterior of the charge case 110 and/or the charge lid 120. For example, with reference to FIG. 2A and without limitation, the external clip assembly according to an exemplary embodiment includes a first clip 140a on one face wall 110a of the charge case 110 and a second clip 140b on the opposing face wall 110a.

With additional reference to FIGS. 7 and 14, each clip 140 includes an inward bend forming a hook end 145 at a top (or, first) end of the clip 140, and a wave-shaped end 143 at a bottom (or, second) end of the clip 140. At the wave-shaped end 143, the clip 140 bends inward and includes a pocket 143a with a contour that is concave relative to a bottom surface 115 of the charge case 110 and extends to form a bulge 143b that is adjacent to the pocket 143a and convex relative to the bottom surface 115 of the charge case 110. The clip 140 fastens the charge lid 120 to the charge case 110. For example, the hook end 145 receives the retainer ring 130 within a groove 149 defined by the hook end 145, and the retainer ring 130 includes a cutout area 132 for accommodating a portion of the hook end 145 that is positioned between the charge lid 120 and the retainer ring 130, at a top connecting area 141 of the encapsulated shaped charge 100. The bulge 143b of the wave-shaped end 143 is dimensioned to fit within a track 118 formed in the bottom surface 115 of the charge case 110, at a bottom connecting area 142 of the encapsulated shaped charge 100 (FIG. 5). With additional reference to FIG. 15, the pocket 143a is dimensioned for accommodating an edge 118a of the charge case 110 when the clip 140 is attached thereto. The edge 118a may form one side of the track 118.

The clip 140 may be formed from a resilient material including a metal, plastic, or stiff elastomer, and dimensioned such that a resilient force of the clip 140 pulls the hook end 145 and the wave-shaped end 143 towards each other, after the clip 140 has been positioned on the encapsulated shaped charge 100. In an aspect, and with particular reference to FIGS. 3 and 5, each clip 140 is positioned on a respective face wall 110a, i.e., extending along at least a portion of the respective face wall 110a, on the exterior of the charge case 110. Each clip 140 is connected at the top, i.e., hook end 145, to the retainer ring 130 and thereby the charge lid 120. Each clip 140 extends from the hook end 145 to the bottom, i.e., wave-shaped end 143, and is connected at the wave-shaped end 143 to the bottom surface 115 of the charge case 110. The resilient force thereby fastens the charge lid 120 to the charge case 110, in normal operation.

The retainer ring 130 may be made of, for example and without limitation, plastic or other resilient material consistent with this disclosure. In the exemplary embodiments as shown in FIGS. 2B, 3, 8, and 13, the retainer ring 130 includes at least one beveled edge 131. The beveled edge 131 may help to facilitate an enhanced fit between the charge lid 120 and the charge case 110. For example, the beveled edge 131 of the retainer ring 130 may provide more surface area than, in contrast, orthogonal sides against which the hook end 145 may engage and exert a force towards the charge case 110. As seen, for instance, in FIG. 2B, it is contemplated that the charge case 110 and the charge lid 120 may also include beveled edges 133, 134. The respective beveled edges 133, 134 on the charge lid 120 and the charge case 110 may help to reduce the overall diameter of the encapsulated shaped charge 100 so that the encapsulated shaped charge 100 can fit into wellbore casings having smaller or reduced inner diameters.

If the encapsulated shaped charge 100 experiences, e.g., high temperatures, the retainer ring 130 is configured to melt or burn and thereby release each clip 140 that is supported on the retainer ring 130. Thus, the clips 140 will disengage from the encapsulated shaped charge 100, and the charge lid 120 will no longer be held to the charge case 110. Gas pressure within the charge case 110 may then vent through a separation between the charge lid 120 and the charge case 110, and the venting may prevent a potentially damaging buildup of pressure within the charge case 110.

With reference now to FIGS. 9 and 12, the charge lid 120 includes a body portion 123, a neck portion 124, and a top lid surface 126. In an aspect, and with additional reference to FIGS. 1, 4, and 10A-10B, the body portion 123 includes an outer lip 125a and an inner lip 125b extending downwardly from the inside portion 122 of the charge lid 120. The outer lip 125a is positioned along a periphery of the body portion 123 and the inner lip 125b is spaced apart from the outer lip 125a. The channel 125 for receiving the o-ring 150 is defined between the inner lip 125b and the outer lip 125a. The body portion 123 is dimensioned for the inner lip 125b, the outer lip 125a, and the channel 125 (and the o-ring 150, when inserted) to extend substantially contiguously with an upper surface 170 of the charge case 110, when the charge lid 120 is positioned on the charge case 110. For purposes of this disclosure, “substantially contiguously” and other terms of relative measure are used to aid in understanding the exemplary embodiments according to the features, functions, and relationships of components but without limitation thereto. For example, as shown in FIG. 1, the outer lip 125a, the channel 125, and the inner lip 125b are positioned next to or share a border with the upper surface 170 of the charge case 110, to form a sealable closure between the charge case 110 and the charge lid 120.

With particular reference to FIGS. 1 and 10B, the inner skirt 121 extends downwardly from the inside portion 122 of the charge lid 120 to a position below the inner lip 125b. The inner skirt 121 is dimensioned to extend contiguously along a portion of an inner surface 175 of the charge chase 110 within the case interior 116.

With reference back to FIGS. 9 and 12, the body portion 123 includes a top surface defining the shoulder 127, which is bound on an inside by the neck portion 124. The shoulder 127 is, in the exemplary embodiments but without limitation thereto, a substantially planar surface. For example, the shoulder 127 is configured for receiving the retainer ring 130 thereon. The neck portion 124 extends generally upwardly from the shoulder portion 127. The top lid surface 126 is positioned above the neck portion 124. In an aspect, the neck portion 124 may extend inwardly, transitioning to the charge lid beveled edge 133 and then the top lid surface 126. While the various charge lid portions 123, 124, 126, 133 are identified to aid in understanding the exemplary embodiments, they are not limited to any particular boundaries, configurations, geometries, delineations, dimensions, etc. of the charge lid 120.

FIGS. 16A-19B show exemplary embodiments of a fastening assembly 160 configured for holding components of an encapsulated conical shaped charge 800 together. The encapsulated conical shaped charge 800 includes, as previously discussed, a charge lid 120 and a charge case 110, albeit having a generally circular geometry. In each of the exemplary embodiments, the fastening assembly 160 includes an external clip assembly 140 and a retainer ring 130 as previously discussed. However, the exemplary embodiments of an external clip assembly 140 as shown in FIGS. 16A-19B include an annular end 148 configured for slipping over a head portion 810 of the charge lid 120, or around the charge case 110, to prevent the clips 140 from falling off and disengaging the charge lid 120 from the charge case 110. A connection end 144 opposite the annular end 148 includes a contour or configuration that allows the connection end 144 to couple with, for example, a groove 119 in the charge case 110, the retainer ring 130, a rounded bottom 113 of the charge case 110, or the charge lid 120. As previously discussed, the retainer ring 130 may be configured to melt or burn upon exposure to fire. In response to the retainer ring 130 melting or burning, at least one of the charge case 110, the charge lid 120, and the clip 140 may have a degree of movement through the space previously occupied by the retainer ring 130, thereby allowing the charge lid 120 to separate from the charge case 110 at least sufficiently to vent any gas pressure that has built up within the charge case 110. In these or other embodiments, the clip 140 may be configured to melt or burn upon exposure to fire, such that the charge lid 120 and the charge case 110 are no longer fastened. In such embodiments the retainer ring 130 may be made from a resilient material that provides a fastening structure for the clip 140 and a compression against, e.g., the charge case 110 or charge lid 120, which may strengthen the coupling therebetween.

FIG. 20 shows an exemplary exposed perforating gun system 200 including a charge carrier 210 that retains and orients encapsulated shaped charges 100. In FIG. 20, the encapsulated shaped charges are encapsulated slotted shaped charges 100 according to the exemplary embodiments discussed throughout this disclosure.

In an aspect, the disclosure relates to a method for reducing a buildup of gas pressure in an encapsulated shaped charge exposed to fire. With reference to the exemplary embodiments of an encapsulated shaped charge 100, 800 as discussed throughout this disclosure, the method may include providing the encapsulated shaped charge 100, 800 with a charge case 110 holding an explosive 111 and a liner 112, a charge lid 120 covering an open end 117 of the charge case 110, and a fastening assembly 160 connected to each of the charge case 110 and the charge lid 120. The fastening assembly 160 may include a retainer ring 130 and an external clip assembly 140. The retainer ring 130 and/or the external clip assembly 140 may be configured to melt or burn and thereby release the external clip assembly 140, when the encapsulated shaped charge 100, 800 is exposed to fire.

More specifically, an exemplary embodiment of a method for reducing a buildup of gas pressure in an encapsulated shaped charge 100, 800 exposed to fire includes enclosing an explosive 111 within a charge case 110 and positioning a charge lid 120 on an open end 117 of the charge case 110 within which the explosive 111 is contained. The method may further include releasably connecting the charge lid 120 to the charge case 110. For example, releasably connecting the charge lid 120 to the charge case 110 may include positioning a retainer ring 130 on the charge lid 120, connecting a first end (e.g., hook end 145) of the external clip assembly 140 to the retainer ring 130, and connecting a second end (e.g. wave-shaped end 143) of the external clip assembly 140 to a bottom 113 or a bottom surface 115 of the charge case 110. In an aspect, the retainer ring 130 is configured to melt or burn in response to exposure to fire. The method may further include releasing the external clip assembly 140 from the charge lid 120 and/or encapsulated shaped charge 100, 800, in response to the retainer ring 130 melting or burning. In response to the external clip assembly 140 being released from the charge lid 120 and/or encapsulated shaped charge 100, 800, the charge lid 120 is separable from the charge case 110 at least sufficiently to release gas pressure that has built up within the charge case 110.

In an aspect of the exemplary method, the external clip assembly 140 may extend from the bottom 113 or the bottom surface 115 of the charge case 110 to the retainer ring 130 positioned on the charge lid 120. The external clip assembly 140 may be formed from a resilient material.

With reference now to FIGS. 21-26, a further exemplary embodiment of an encapsulated shaped charge 100 is shown. The encapsulated shaped charge 100 shown in FIGS. 21-26 is configured substantially according to the exemplary embodiments shown and described above with respect to FIGS. 1-15, except where otherwise noted and/or not inconsistent therewith. Accordingly, common aspects may not necessarily be repeated but form part of the disclosure of the exemplary embodiments shown in FIGS. 21-26, to the extent they are not inconsistent.

For example, the exemplary embodiments shown in FIGS. 21-26 include a charge case 110 and a charge lid 120, and the charge lid 120 includes an inner skirt 121 extending downwardly from an inside portion 122 of the charge lid 120. In an aspect, the charge lid 120 further includes an angled section 310 on each side of the charge lid 120 corresponding to the face walls 110a of the charge case 110. The encapsulated shaped charge 100 further includes an external clip assembly including opposing clips 140 each connected at a hook end 145 to a retainer ring 130 positioned on the charge lid 120. Each clip 140 is positioned next to a respective angled section 310. In the event that the retainer ring 130 melts or burns, the hook end 145 of the clip 140 may easily slip along the angled section 310, to release the charge lid 120.

In a further aspect and as illustrated in FIG. 23, FIG. 25 and FIG. 26, the inside portion 122 of the charge lid 120 includes a weakened zone 320 defined by a reduced local thickness of the charge lid 120. In an aspect, the weakened zone 320 is formed in a dome-like shape. The exemplary configuration may contribute to the ballistic performance of the encapsulated shaped charge 100 while not sacrificing the pressure rating. For example, the weakened zone 320 may contribute to maintaining or maximizing the cutting force of a perforating jet passing through the charge lid 120 to sever control lines behind a wellbore casing, in a representative application.

In a further aspect, the inner skirt 121 includes a gap 330 on short sides 123 of the inner skirt 121 corresponding to the side walls 110b of the charge case 110. The gap 330 may allow gasses to escape from within the charge case 110 in the event of a fire exposure. The gap 330 is formed, e.g., as a void between a first skirt portion 121a and a second skirt portion 121b.

In an aspect of the exemplary embodiments, the external clip assembly including one or both of the opposing clips 140 is bendable and resiliently connects to each of the charge case 110 and the charge lid 120. The one or both of the opposing clips 140 may be formed from a bendable steel or metal. The configuration and features of the external clip assembly, i.e., a bendable, resiliently connectable clip that extends vertically from the charge case 110 to the charge lid 120 on an outside of the encapsulated shaped charge 110, may avoid the need to crimp a charge lid to a charge case to form an encapsulated shaped charge. Accordingly, the exemplary configuration may avoid the need to crimp a charge lid to a charge case, which may avoid potential safety and operational issues created by, e.g., accidental deformation of seal surfaces.

Further, removing the need to crimp the charge lid to the charge case may provide an easier manufacturing method with cost savings and greater efficiency. For example, when crimping is used, non-axisymmetrically shaped encapsulated charges may require custom planning for individual designs.

In addition, the outside position of the external clip assembly allows the retainer ring 130 to be similarly positioned on the outside of the encapsulated shaped charge 100, thereby exposing the retainer ring 130 directly to flame/heat that may trigger melting or burning of the retainer ring 130. This may provide greater safety over, e.g., encapsulated shaped charges in which a melt ring is positioned within the metal of a charge lid or charge case, and therefore requires additional time to melt as the metal heats up.

In an aspect of the exemplary embodiments and as illustrated in FIGS. 23 and 25, for example, the seal, i.e., o-ring 150, is positioned on the charge lid 120 within the channel 125 formed in the inside portion 122 of the charge lid 120. The exemplary configuration may avoid issues created by, e.g., placing a seal on the charge case near the explosives contained therein, which may affect the integrity of the seal, and/or safety and ballistic performance of the encapsulated shaped charge if, e.g., explosives are accidentally deposited on the o-ring or within a groove in which the o-ring is positioned. Further, the exemplary configuration of the o-ring 150 within the channel 125 on the inside portion 122 of the charge lid 120 removes the o-ring 150 from venting passage(s) and, accordingly, the o-ring 150 need not participate in the venting process.

In an aspect of the exemplary embodiments, the retainer ring 130 is made from a polyamide, for example PA6.

Embodiments described herein relate generally to devices, systems, and methods for an encapsulated shaped charge for an exposed perforating gun system, and associated systems and methods. For purposes of this disclosure, the phrases “devices,” “systems,” and “methods” may be used either individually or in any combination referring without limitation to disclosed components, grouping, arrangements, steps, functions, or processes.

This disclosure, in various embodiments, configurations and aspects, includes components, methods, processes, systems, and/or apparatuses as depicted and described herein, including various embodiments, sub-combinations, and subsets thereof. This disclosure contemplates, in various embodiments, configurations and aspects, the actual or optional use or inclusion of, e.g., components or processes as may be well-known or understood in the art and consistent with this disclosure though not depicted and/or described herein.

The phrases “at least one”, “one or more”, and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together.

In this specification and the claims that follow, reference will be made to a number of terms that have the following meanings. The terms “a” (or “an”) and “the” refer to one or more of that entity, thereby including plural referents unless the context clearly dictates otherwise. As such, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. Furthermore, references to “one embodiment”, “some embodiments”, “an embodiment” and the like are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term such as “about” is not to be limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Terms such as “first,” “second,” “upper,” “lower” etc. are used to identify one element from another, and unless otherwise specified are not meant to refer to a particular order or number of elements.

As used herein, the terms “may” and “may be” indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of “may” and “may be” indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances the modified term may sometimes not be appropriate, capable, or suitable. For example, in some circumstances an event or capacity can be expected, while in other circumstances the event or capacity cannot occur—this distinction is captured by the terms “may” and “may be.”

As used in the claims, the word “comprises” and its grammatical variants logically also subtend and include phrases of varying and differing extent such as for example, but not limited thereto, “consisting essentially of” and “consisting of.” Where necessary, ranges have been supplied, and those ranges are inclusive of all sub-ranges therebetween. It is to be expected that the appended claims should cover variations in the ranges except where this disclosure makes clear the use of a particular range in certain embodiments.

The terms “determine”, “calculate” and “compute,” and variations thereof, as used herein, are used interchangeably and include any type of methodology, process, mathematical operation or technique.

This disclosure is presented for purposes of illustration and description. This disclosure is not limited to the form or forms disclosed herein. In the Detailed Description of this disclosure, for example, various features of some exemplary embodiments are grouped together to representatively describe those and other contemplated embodiments, configurations, and aspects, to the extent that including in this disclosure a description of every potential embodiment, variant, and combination of features is not feasible. Thus, the features of the disclosed embodiments, configurations, and aspects may be combined in alternate embodiments, configurations, and aspects not expressly discussed above. For example, the features recited in the following claims lie in less than all features of a single disclosed embodiment, configuration, or aspect. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this disclosure.

Advances in science and technology may provide variations that are not necessarily express in the terminology of this disclosure although the claims would not necessarily exclude these variations.

Claims

1. An encapsulated shaped charge, comprising: a charge case holding an explosive and a liner;a charge lid covering an open end of the charge case; andan external clip assembly connected to each of the charge case and the charge lid;wherein the charge lid includes an inner skirt extending downwardly from an inside portion of the charge lid; andthe inner skirt includes a gap.

2. The encapsulated shaped charge of claim 1, wherein the external clip assembly includes a first clip on a first face wall of the charge case and a second clip on a second face wall opposite the first face wall of the charge case, wherein the first clip and the second clip are each connected to a retainer ring positioned on the charge lid.

3. The encapsulated shaped charge of claim 2, wherein the retainer ring is formed from a plastic.

4. The encapsulated shaped charge of claim 2, wherein the retainer ring is made from a polyamide.

5. The encapsulated shaped charge of claim 4, wherein the polyamide is PA6.

6. The encapsulated shaped charge of claim 2, wherein the retainer ring is configured to melt or burn, and release one or both of the first clip and the second clip, in response to the encapsulated shaped charge being exposed to fire.

7. The encapsulated shaped charge of claim 1, wherein the charge lid includes an angled section, the external clip assembly includes a clip, and the clip is positioned next to the angled section.

8. The encapsulated shaped charge of claim 1, wherein the charge lid includes a weakened zone defined by a reduced local thickness on an inside portion of the charge lid.

9. The encapsulated shaped charge of claim 8, wherein the weakened zone is dome shaped.

10. The encapsulated shaped charge of claim 1, wherein the gap is formed as a void between a first skirt portion and a second skirt portion.

11. The encapsulated shaped charge of claim 1, wherein the external clip assembly includes a clip configured to melt or burn in response to the encapsulated shaped charge being exposed to fire.

12. The encapsulated shaped charge of claim 1, wherein the external clip assembly includes a clip, wherein the clip is bendable and resiliently connects to each of the charge case and the charge lid.

13. The encapsulated shaped charge of claim 12, wherein the clip is formed from a bendable steel or metal.

14. The encapsulated shaped charge of claim 1, further comprising a seal positioned on the charge lid.

15. The encapsulated shaped charge of claim 14, wherein the seal is an o-ring positioned in a channel formed in the charge lid.

16. An exposed perforating gun system, comprising: a charge carrier retaining a plurality of encapsulated shaped charges, wherein each encapsulated shaped charge includes:a charge case holding an explosive and a liner,a charge lid covering an open end of the charge case, andan external clip assembly connected to each of the charge case and the charge lid;wherein the charge lid includes an inner skirt extending downwardly from an inside portion of the charge lid; andthe inner skirt includes a gap.

17. A method for reducing a buildup of gas pressure in an encapsulated shaped charge exposed to fire, comprising: enclosing an explosive within a charge case, wherein the step of enclosing the explosive includes positioning a charge lid on an open end of the charge case within which the explosive is contained;releasably connecting the charge lid to the charge case, wherein releasably connecting the charge lid to the charge case includes positioning a retainer ring on the charge lid, andconnecting a first end of a clip to the retainer ring and a second end of the clip to a bottom surface of the charge case, wherein the retainer ring is configured to melt or burn in response to exposure to fire; andreleasing the clip from the retainer ring, in response to the retainer ring melting or burning in response to exposure to fire.

18. The method of claim 17, wherein the clip extends from the bottom surface of the charge case to the retainer ring on the charge lid, and the clip is formed from a resilient material.