INTERVENING SHAPED CHARGE LINER

Abstract

The present disclosure relates to shaped charge. The shaped charge includes an explosive component having a first density and a first mechanical strength. The shaped charge also includes a liner member having a second density and a second mechanical strength. Further, the shaped charge includes an intervening liner member having a third density and a third mechanical strength. The intervening liner member is disposed between the explosive component and the liner member. The intervening liner member has one or both of: the third density being between the first density and the second density; and the third mechanical strength being between the first mechanical strength and the second mechanical strength.

Claims

1. A shaped charge, comprising: an explosive component having a first density and a first mechanical strength; a liner member having a second density and a second mechanical strength; and an intervening liner member having a third density and a third mechanical strength, wherein the intervening liner member is disposed between the explosive component and the liner member, wherein one or both of: the third density is between the first density and the second density; and the third mechanical strength is between the first mechanical strength and the second mechanical strength.

2. The shaped charge of claim 1, wherein the intervening liner member is a thermoplastic material.

3. The shaped charge of claim 1, wherein the intervening liner member is a metal film or sheet.

4. The shaped charge of claim 3, wherein the intervening liner member consists essentially of calcium, aluminum, barium, or beryllium.

5. The shaped charge of claim 1, wherein the intervening liner member is hydrodynamically equivalent to less than or equal to 20 wt % of a total mass of the intervening liner member and the liner member.

6. The shaped charge of claim 1, wherein the intervening liner member is hydrodynamically equivalent to less than or equal to 10 wt % of a total mass of the intervening liner member and the liner member.

7. The shaped charge of claim 1, comprising an additional intervening liner member comprising a fourth density and a fourth mechanical strength, wherein the fourth density is between the first density and the second density, and wherein the fourth mechanical strength is between the first mechanical strength and the second mechanical strength.

8. The shaped charge of claim 1, wherein the third density of the intervening liner member is less than 8 g/cc.

9. The shaped charge of claim 1, wherein the third mechanical strength of the intervening liner member is less than 100 MPa.

10. A shaped charge, comprising: an explosive component having a first density and a first mechanical strength; a liner member having a second density and a second mechanical strength; and an intervening liner member comprising a plurality of material layers, wherein each material layer of the plurality of material players comprise a density that is between the first density and the second density, wherein each material layer of the plurality of material players comprise a mechanical strength that is between the first mechanical strength and the mechanical strength, and wherein the intervening liner member is disposed between the explosive component and the liner member.

11. The shaped charge of claim 10, wherein the plurality of material layers are arranged in order of increasing density along a direction from the explosive component to the liner member.

12. The shaped charge of claim 10, wherein the plurality of material layers are arranged in order of increasing mechanical strength along a direction from the explosive component to the liner member.

13. The shaped charge of claim 10, wherein the intervening liner member is a metal film or sheet.

14. The shaped charge of claim 10, wherein the intervening liner member is hydrodynamically equivalent to approximately 10 wt % to 20 wt % of a total mass of the intervening liner member and the liner member.

15. The shaped charge of claim 10, wherein the intervening liner member is a thermoplastic material.

16. A method, comprising: providing an intervening liner member for a shaped charge; providing a primary liner member; and assembling the shaped charge such that the intervening liner member is disposed between the primary liner member and an explosive component of the shaped charge.

17. The method of claim 16, wherein the intervening liner member comprises a plurality of layers.

18. The method of claim 17, wherein providing the intervening liner member comprising forming the plurality of layers arranged in order of increasing density.

19. The method of claim 17, wherein providing the intervening liner member comprising forming the plurality of layers arranged in order of increasing mechanical strength.

20. The method of claim 16, wherein a thickness of the intervening liner member is less than a thickness of the primary liner member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0013] FIG. 1 shows a perforation operation, in accordance with aspects of the present disclosure;

[0014] FIG. 2 shows a diagram illustrating a perforation being made with a perforation gun, in accordance with aspects of the present disclosure;

[0015] FIG. 3 shows a diagram illustrating a perforation and a tunnel made with a shaped charge, in accordance with aspects of the present disclosure;

[0016] FIG. 4 shows a cross-sectional view of an embodiment of a shaped charge, in accordance with aspects of the present disclosure;

[0017] FIG. 5A shows a diagram of the shaped charge of FIG. 4 forming a first type of jet, in accordance with aspects of the present disclosure;

[0018] FIG. 5B shows a diagram of the shaped charge of FIG. 4 forming a second type of jet, in accordance with aspects of the present disclosure;

[0019] FIG. 5C shows a diagram of the shaped charge of FIG. 4 forming a third type of jet, in accordance with aspects of the present disclosure;

[0020] FIG. 6 shows a cross-sectional view of an embodiment of a shaped charge that includes an intervening liner member disposed between an explosive component and a liner member of a shaped charge, in accordance with aspects of the present disclosure;

[0021] FIG. 7 shows a cross-sectional view of an embodiment of a shaped charge that includes a multi-layered intervening liner member disposed between an explosive component and a liner member of a shaped charge, in accordance with aspects of the present disclosure; and

[0022] FIG. 8 shows a flow diagram of a method for assembling a multi-part shaped charge liner, in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

[0023] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0024] When introducing elements of various embodiments of the present disclosure, the articles a, an, and the are intended to mean that there are one or more of the elements. The terms comprising, including, and having are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to one embodiment or an embodiment of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0025] As discussed above, shaped charges are used for a variety of oil and gas applications. In particular, the jet formed by the detonation of a given shaped charge may pierce a steel casing, cement, and a variety of different types of rock that make up the surrounding formation. The characteristics of the jet produced by a shaped charge are largely dependent upon the behavior of the liner and other shaped charge components upon detonation. At least in some instances, it may be advantageous to produce a jet from a material of a collapsing liner to puncture or sever certain areas in a wellbore, while not severing others. For example, it may be advantageous to sever a control line behind a completion prior to cementing as part of a plug and abandonment operation. To create such a jet, it may be advantageous to use relatively high density materials (e.g., metals) to form the liner in the shaped charge. However, there may be certain limitations in pressed liners or green compacts (e.g., pressed components) for shaped charges. As referred to herein, a green compact is a compact formed by pressurizing and cooling a powder to form a dense, solid mass, where the powders are held together by friction between the particles, as opposed to sintering the metal powders. As referred to herein, a green density refers to the density of a pressed compact. In any case, each jet produced from a shaped charge may have some variability in shape, power, speed, and so on. The variability between each jet (i.e., shot-to-shot variation) reduces the predictability during operation of shaped charges and, thus, can result in unexpected operations of the shaped charge, such as failing and/or incomplete piercing or severing of the wellbore.

[0026] Without wishing to be bound by theory, it is believed that one of the main influences of shot-to-shot variation and causes of jet breakup may be the result of the Rayleigh-Taylor (RT) instability. RT instability arises at the interface between two fluids of different density where the lighter fluid is pushing (e.g., normal pressure) against the heavier fluid. In the case of a shaped charge, RT instability occurs at the interface of the explosive component and liner member (i.e., which are substantially a fluid at the extreme pressures present inside a shaped charge). In particular, the explosive material of the explosive component has become a gaseous by-product and is now at high pressure acting to accelerate the liner member towards the central axis and into jet formation. Assuming that the properties of the explosive products are fixed, it is believed that the mechanical properties of the liner member that influence RT instability may be the mechanical strength and density of the liner member. For example, without wishing to be bound by theory, it is believed that a greater mismatch between the mechanical strength (e.g., a mechanical strength mismatch of 500 MPa or greater, 600 MPa or greater, 700 MPa or greater, or 800 MPa or greater) and/or the density (e.g., a density mismatch of 4 g/cc or greater, 5 g/cc or greater, 6 g/cc or greater) of the explosive component and the liner member) produces an RT instability that results in unexpected shot-to-shot variation. As discussed above, the liner members are predominantly pressed powder liners and, thus, may not have much strength in tension and have relatively limited strength at the onset of compaction (i.e., in relation the scale of the pressures applied). Further, particularly for deep penetrators, the powder mixture is near to the density of tungsten, which is highly dense; again the worst case.

[0027] Accordingly, the present disclosure relates to an intervening liner member that bridges a gap between the mechanical properties of the explosive component and the liner member. In general, the disclosed intervening liner member has physical properties that are between the physical properties of the explosive component and the liner member. The intervening liner member may be formed of certain thermoplastics (e.g., thermoplastic materials) and/or metal sheets or metal films. In some embodiments, the intervening liner member may be formed of one or more powdered metals (e.g., powdered metal mixtures). In certain embodiments, the intervening liner member may be a multi-layered intervening liner member formed of one or more different materials (e.g., thermoplastics and/or metal sheets or films). In such embodiments, the multi-layered intervening liner member may include a gradually increasing or decreasing density and/or strength. That is, each layer of the multi-layered intervening liner member (e.g., each layer may be referred to as an additional intervening liner member) may have an increasing density and/or strength from a first end of a first layer that couples the explosive component to a second end of a second layer that couples to the liner member. In this way, the differences in mechanical properties at the interface(s) between the explosive component and the liner member are reduced, thereby reducing the effect of RT instability. Accordingly, the disclosed intervening liner member may provide a shaped charge that has relatively less shot-to-shot variation as compared to conventional shaped charges.

[0028] With reference to FIG. 1, after a well 10 is drilled, a casing 12 is typically run in the well 10 and cemented to the well 10 in order to maintain well integrity. After the casing 12 has been cemented in the well 10, one or more sections of the casing 12 that are adjacent to the formation zones of interest (e.g., target well zone 13) may be perforated to allow fluid from the formation zones to flow into the well for production to the surface or to allow injection fluids to be applied into the formation zones. To perforate a casing section, a perforating gun string may be lowered into the well 10 to a desired depth (e.g., at target zone 13), and one or more perforation guns 15 may be fired to create openings in the casing 12 and to extend perforations into the surrounding formation 16. Production fluids in the perforated formation 16 can then flow through the perforations and the casing openings into the wellbore 11.

[0029] Typically, perforating guns 15 (which include gun carriers and shaped charges mounted on or in the gun carriers or, alternatively, include sealed capsule charges) are lowered through tubing or other pipes to the desired formation interval on a line 17 (e.g., wireline, e-line, slickline, coiled tubing, and so forth). The charges carried in a perforating gun 15 may be phased to fire in multiple directions around the circumference of the wellbore 11. Alternatively, the charges may be aligned in a straight line. When fired, the charges create perforating jets that form holes in the surrounding casing 12 as well as extend perforation tunnels into the surrounding formation 16.

[0030] With reference to FIG. 1, certain embodiments of the present disclosure include a perforation system comprising: (1) a perforating gun 15 (or gun string), wherein each gun may be a carrier gun (as shown) or a capsule gun (not shown); and (2) one or more improved shaped charges 20 loaded into the perforating gun 15 (or into each gun of the gun string), each charge having a liner member, as described herein; and (3) a conveyance mechanism 17 for deploying the perforating gun 15 (or gun string) into a wellbore 11 to align at least one of said shaped charges 20 within a target formation interval 13, wherein the conveyance mechanism may be a wireline, tubing, or other conventional perforating deployment structure; among other components.

[0031] Examples of explosives (e.g., explosive component as described in FIG. 4) that may be used in the various explosive components (e.g., charges, detonating cord, and boosters) include RDX (cyclotrimethylenetrinitramine or hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (cyclotetramethylenetetranitramine or 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane), TATB (triaminotrinitrobenzene), HNS (hexanitrostilbene), and others.

[0032] Referring to FIGS. 2 and 3, the material from a collapsed liner of the shaped charge 20 (e.g., as described in more detail in FIG. 4) forms a perforating jet 28 that shoots through the front of the shaped charge and penetrates the casing 12 and underlying formation 16 to form a perforated tunnel (or perforation tunnel) 40. Around the surface region adjacent to the perforated tunnel 40, a layer of residue 30 from the charge liner is deposited. The charge liner residue 30 includes wall residue 30A deposited on the wall of the perforating tunnel 40 and tip residue 30B deposited at the tip of the perforating tunnel 40. As described in more detail with respect to FIG. 5, adjusting properties of the shaped charge 20 (e.g., the geometry of the liner, the density of the liner, the mechanical strength of the liner, and so on) may adjust jet properties (e.g., jet velocity and/or jet shape) of the perforating jet 28.

[0033] Referring now to FIG. 4, a cross sectional view of an embodiment of a shaped charge 20 is shown. The shaped charge 20 includes a casing member 42 and an interior volume 44 that is defined by an explosive component 46 and a liner member 48 (e.g., primary liner member). The explosive component 46 is disposed between the casing member 42 and the liner member 48 such that the liner member 48 surrounds the interior volume 44.

[0034] The liner member 48 may be formed of packed, powered metals and, in at least in some instances, non-metallic materials. The metals of the liner member 48 may include metals having a density of approximately 6 or greater grams per cubic centimeter (g/cc), 7 or greater g/cc, 8 or greater g/cc, 9 or greater g/cc 10 or greater g/cc, 11 or greater g/cc, 12 or greater g/cc, or 13 or greater g/cc, and so on. In some embodiments, the metals of the liner member 48 may include metals having a density less than approximately 6 g/cc (e.g., aluminum, beryllium, titanium, and so on). For example, the liner member 48 may include copper (e.g., having a density of approximately 8.9 g/cc) and/or lead (e.g., having a density of approximately 11.3 g/cc). In some embodiments, the liner member 48 may include tungsten (e.g., having a density of approximately 19.3 g/cc). In some embodiments, the liner member 48 may include a mixture of metals, which may provide a desired density. For example, the liner member 48 may include approximately 50 weight percent (wt %) or greater, approximately 60 wt % or greater, approximately 70 wt % or greater, approximately 80 wt % or greater, or approximately 90 wt % or greater of a first metal (e.g., tungsten). Further, the liner member 48 may include a remaining wt % of a second metal (e.g., copper or lead), such as approximately 10 wt % or less, 20 wt % or less, 30 wt % or less, and so on.

[0035] As mentioned above, the liner member 48 may also include non-metallic materials, such as nitrides, carbides, oxides, diamond, ceramic materials, or a combination thereof. For example, the liner member 48 may include relatively low density materials (e.g., as compared to the metals), such as SiC, Si.sub.3N.sub.4, SiO.sub.2, B.sub.4C, B.sub.4N, ZnO, TiC, Li.sub.3N, TiO.sub.2, Mg.sub.3N.sub.2, and other relatively low density non-metallic materials. In some embodiments, the liner member 48 may include a polymer material, such as fluorinated polymers (e.g., polytetraflouroethylene). In some embodiments, the liner member 48 may include metal-polymer composite mixtures. In such embodiments, the liner member 48 may include a first weight percent (wt %) (e.g., first amount) of one or more metals and a second wt % of one or more non-metallic materials. For example, the liner member 48 may include approximately 50 wt % or greater, 60 wt % or greater, 70 wt % or greater, 80 wt % or greater, 90 wt % or greater of one or more metals. As such, the liner member 48 may include approximately 50 wt % or less, 40 wt % or less, 30 wt % or less, 20 wt % or less, or 10 wt % or less of one or more non-metallic materials.

[0036] Referring specifically now to FIGS. 5A, 5B, and 5C (e.g., collectively FIGS. 5A-5C), side cross-sectional views of a different types of shaped charges 20a, 20b, and 20c in use during perforating applications are shown. That is, in each case, a charge 20a, 20b, and 20c has been loaded into a perforating gun (not shown), and utilized in a perforating application in a well 10. The charges 20a, 20b, and 20c may be made up of generally the same features described with respect to FIG. 1. For example, the charges 20a, 20b, and 20c may include the same type of casing 12 and explosive component 46. However, in each case, a different type of liner member 48a, 48b, and 48c may be used to provide a different type of charge 20a, 20b, and 20c for a different type of perforating application.

[0037] With reference to FIG. 5A in particular, a deep penetrating jet shaped charge 20a is shown. Upon detonation, a deep penetrating jet 28a is formed and directed at the casing 12 that defines the well 10. Ultimately, this forms a perforation tunnel 40a that penetrates through the casing member 42, cement 49, and into the adjacent formation 16 so as to aid in hydrocarbon recovery therefrom. In the embodiment shown, the liner 48a that is used to form the jet 28a and achieve such penetration may be a comparatively thin but high-density tungsten-based liner member 48a so as to form a thinner and longer jet 28a. The end result, depending largely on the particular characteristics of the casing 12, may be a perforation tunnel 40a of between approximately 30 and approximately 40 inches deep with a diameter of between approximately 0.3 inches and approximately 0.4 inches.

[0038] Of course, as depicted in the embodiment of FIG. 5B, a different type of liner member 48b may be utilized to obtain a different type of charge 20b and performance during perforation. More specifically, in the embodiment of FIG. 5B, a side cross-sectional view of wide jet shaped charge 20b is shown. In this case, the liner member 48b is of a comparatively thicker dimensions and lower density, perhaps with a lower percentage of tungsten. Thus, a comparatively thicker or wider jet 28b may be formed. The end result, again depending on characteristics of the casing 12 and other physical factors, may be a shorter perforation tunnel 40b that is closer to a threshold distance (e.g., 60-90 cm deep but with a wider diameter (e.g. between about 1 cm and about 1.3 cm).

[0039] Referring now to FIG. 5C, a side cross-sectional view of a combination jet shaped charge 20c is shown. In this case, the liner member 48c may be of a thickness, density, materials and other characteristics similar to either of the deep penetrating 48a or wide 48b liner member types described above. However, the combination liner member 48c of FIG. 5C is of a uniquely tailored non-uniform morphology. Thus, a combination jet 28c may ultimately be formed such that the perforation tunnel 40c which is formed is also of a uniquely tailored morphology.

[0040] Accordingly, FIGS. 5A-5C show that altering physical properties (e.g., density) of the liner member 48 adjusts the shape of the resulting jet 28. That is, by altering the explosive component 46, the liner member 48, and/or mass distributions of an axisymmetric shaped charged design, the charge may be converted to an alternate symmetry. It is presently recognized that for cutting control lines, it may be advantageous to use a shaped charge having a planar symmetry, whereby mass is added or removed at pole 180 degrees apart. As a result, during jet collapse, the normally axially uniform fast-moving jet is converted to a slower fan-like geometry that cuts the line spanning multiple degrees from the axis of symmetry serves to provide increase coverage of the cutter while still achieving velocities and densities inside the cutting fan, which are comparable to linear slot cutters, but which can utilize existing hardware and manufacturing methods.

[0041] As described herein, it is presently recognized that it may be advantageous to form an intervening liner member (e.g., an intervening shaped charge liner) that bridges the gap between the mechanical properties (e.g., strength, density, and so on) between the explosive component 46 and the liner member 48. To illustrate this, FIG. 6 shows a cross-sectional view of a shaped charge 20 having an intervening liner member 50 in accordance with the present disclosure. In some embodiments, the intervening liner member 50 may be formed of thermoplastics (e.g., polyacrylic acids (PAA), poly(methyl methacrylate) (PMMA), polyamides, polyether ether ketone (PEEK), polyethylene (PE). In some embodiments, the intervening liner member 50 may be formed a metal sheets or films.

[0042] As described above, the liner member 48 may be formed of packed, powered metals and, at least in some instances, non-metallic materials. The metals of the liner member 48 may include metals having a density of approximately 8 or greater grams per cubic centimeter (g/cc), 9 or greater g/cc, 10 or greater g/cc, 11 or greater g/cc, 12 or greater g/cc, or 13 or greater g/cc, and so on. The explosive component 46 may be formed of relatively less dense oxidizers (e.g., carbon, KClO.sub.4, KClO.sub.3, KNO.sub.3, etc.), explosive materials, propellants, or a combination thereof. For example, the explosive component 46 may have a density of approximately 3 or less g/cc, 2.5 or less g/cc, 2.2 or less g/cc, 2.0 or less g/cc, 1.8 or less g/cc, and so on. In some embodiments, the explosive component 46 may have a density between approximately 1 to 3 g/cc, 1.5 to 3 g/cc, 1.8 to 3 g/cc, or 1.8 to 2.5 g/cc.

[0043] As such, the intervening liner member 50 may be formed of materials having a density that is between the density of the explosive component 46 and the liner member 48. That is, the explosive component 46 may have a first density, the liner member 48 may have a second density, and the intervening liner member 50 (e.g., or one or more layers of the intervening liner member 50 as described in FIG. 7) may have a third density between the first density and the second density. For example, the intervening liner member 50 may have a density between approximately 2.5 g/cc and 8 g/cc, 3 g/cc to 8 g/cc, 2.5 to 7 g/cc, 2.5 to 6 g/cc, 3 to 7 g/cc, 3 to 6 g/cc, or 3 to 5 g/cc. For example, the intervening liner member 50 may be formed of (e.g., include or consist essentially of) calcium, aluminum, barium, beryllium, or other metals having a relatively low density (e.g., less than 8 g/cc), such that the intervening liner member 50 has a third density that is between the first density of the explosive component 46 and the second density of the liner member 48. For example, the intervening liner member 50 may include different combinations of amounts of metals described herein.

[0044] Additionally or alternatively, the intervening liner member 50 may have a mechanical strength that is between the mechanical strength of the explosive component 46 and the liner member 48. That is, the explosive component 46 may have a first mechanical strength, the liner member 48 may have a second mechanical strength, and the intervening liner member 50 (e.g., or one or more layers of the intervening liner member 50 as described in FIG. 5) may have a third mechanical strength between the first mechanical strength and the second mechanical strength. For example, the liner member 48 may have a mechanical strength (e.g., tensile strength and/or yield strength) that is greater than or equal to 300 Mega Pascals (MPa), greater than or equal to 400 MPa, greater than or equal to 500 MPa, greater than or equal to 600 MPa, greater than or equal to 700 MPa, greater than or equal to 800 MPa, greater than or equal to 900 MPa. The explosive component 46 may have a relatively lower mechanical strength than the liner member 48, such as less than or equal to 100 MPa, less than or equal to 50 MPa, or less than or equal to 40 MPa. As such, the intervening liner member 50 may have a mechanical strength that is between approximately 40 MPa and 300 MPa, between approximately 40 MPa and 500 MPa, between approximately 40 MPa and 600 MPa, between approximately 50 MPa and 300 MPa, between approximately 50 MPa and 500 MPa, or between approximately 50 MPa and 700 MPa.

[0045] As shown in FIG. 6, the intervening liner member 50 includes a generally conical shape having an apex 51 and a skirt section 52 (e.g., that gradually extends radially outward from the apex 51 to an axial end of the skirt section 52, for example, relative to an axis 60). The apex 51 and the skirt section 52 generally define the interior volume 44 (e.g., inner volume) of the intervening liner member 50 where the liner member 48 is disposed. The apex 51 and/or skirt section 52 of the intervening liner member 50 may generally complement the shape of a corresponding apex and skirt section of the liner member 48. Although the illustrated embodiment of the intervening liner member 50 includes an apex 51, it should be noted that in some embodiments the intervening liner member 50 may not include the apex 51, and may only include the skirt section 52. That is, the intervening liner member 50 may not completely cover the liner member 48. Similarly, although the illustrated embodiment of the intervening liner member 50 includes the skirt section 52, it should be noted that in some embodiments the intervening liner member 50 may not include the skirt section 52, and may only include the apex 51.

[0046] The intervening liner member 50 is generally disposed between the explosive component 46 and the liner member 48. For example, and as shown, the intervening liner member 50 may physically couple to the explosive component 46 at a first end 53 (e.g., a first surface along the skirt section 52 and/or the apex 51). Further, the intervening liner member 50 may physically couple to the explosive component 46 at a second end 54 (e.g., a second surface along the skirt section 52 and/or the apex 51).

[0047] The intervening liner member 50 has a thickness 56. In general, the thickness 56 may be relatively smaller than a corresponding thickness 58 of the liner member 48. For example, the thickness 56 of the intervening liner member 50 may be 10% or less, 20% or less, 40% or less, 50% or less, 60% or less, or 70% or less, than the thickness 58 of the liner member 48. It is presently recognized that it may be advantageous to adjust the thickness 56 and/or mass of the intervening liner member 50 such that the intervening liner member 50 is hydrodynamically equivalent to less than the total mass of the intervening liner member 50 and the liner member 48. For example, the intervening liner member 50 may be hydrodynamically equivalent to less than or equal to 20%, less than or equal to 18%, less than or equal to 15%, less than or equal to 12%, or less than or equal to 10% of the total mass of the intervening liner member 50 and the liner member 48. In some embodiments, the intervening liner member 50 may be hydrodynamically equivalent to between approximately 5 to 20%, between approximately 10 to 20%, between approximately 15 to 20%, or between approximately 10 to 15% of the total mass of the intervening liner member 50 and the liner member 48.

[0048] As shown, the intervening liner member 50 extends along the portion 61 of a skirt section 62 of the liner member 48. While the illustrated embodiment shows the skirt section 52 of the intervening liner member 50 extending along approximately the entire skirt section 62 of the liner member 48, it should be noted that the skirt section 52 of the intervening liner member 50 may extend along any suitable portion of the skirt section 62 of the liner member 48, such as 10% or less of the total length 64 of the skirt section 62, 20% or less of the total length 64 of the skirt section 62, 30% or less of the total length 64 of the skirt section 52, 40% or less of the total length 64 of the skirt section 52, 50% or less of the total length 64 of the skirt section 62. However, in other embodiments, the skirt section 52 of the intervening liner member 50 may extend over a majority (e.g., greater than 50% of the total length of the skirt section 62). For example, the skirt section 52 of the intervening liner member 50 may extend along 50% or greater of the total length 64 of the skirt section 62, 60% or greater of the total length 64 of the skirt section 62, 70% of greater of the total length 64 of the skirt section 62, 80% or greater of the total length 64 of the skirt section 62, 90% or greater of the total length 64 of the skirt section 62.

[0049] In some embodiments, the intervening liner member 50 may include multiple layers. To illustrate this, FIG. 7 shows a cross-sectional view of a shaped charge 20 having an intervening liner member 50 with multiple layers 70, 72, and 74, in accordance with the present disclosure. While three layers are shown, it should be noted that the intervening liner member 50 may include any number of layers, such as two layers, three layers, four layers, five layers, or more than five layers.

[0050] In a generally similar manner as described in FIG. 6, the intervening liner member 50 includes a generally conical shape having an apex 51 and a skirt section 52. That is, each layer 70, 72, and 74 may include a corresponding skirt section 52 and apex 51. Further, it should be noted that in some instances, one or more of the layers 70, 72, and 74 may have only a skirt section 52, only an apex 51, or both. As such, rather than having a conical shape, the intervening liner member 50 may have a cylindrical shape.

[0051] The intervening liner member 50 is generally disposed between the explosive component 46 and the liner member 48. In the illustrated embodiment, the first layer 70 is physically coupled to the explosive component 46 at a first end 53 (e.g., first side or first surface). Further, the third layer 74 is physically coupled to the liner member 48 at the second end 54 (e.g., a second side or second surface). The second layer 72 is disposed therebetween and coupled to each of the first layer 70 and the third layer 74.

[0052] The first layer 70, the second layer 72, and the third layer 74 may be arranged in any suitable arrangement such that the difference in mechanical properties at the interface between the explosive component 46 and the liner member 48 is less than the difference in mechanical properties without the intervening liner member 50. For example, the first layer 70, the second layer 72, and the third layer 74 may be arranged in order of increasing density along the direction 76 (e.g., from a position normal to a surface of the explosive component) that extends from the explosive component 46 to the liner member 48. Additionally or alternatively, the first layer 70, the second layer 72, and the third layer 74 may be arranged in order of increasing mechanical strength along the direction 76. In some embodiments, the second layer 72 or any further intervening layers between the first layer 70 and the third layer 74 (e.g., a fourth layer) may have a relatively higher density and/or mechanical strength than the first layer 70, but less than the density and/or mechanical strength of the first layer 74 (e.g., the density may increase from the first layer 70 the second layer 72 and then decrease from the second layer 72 to the third layer 74).

[0053] As illustrated in FIG. 7, the intervening liner member 50 may have a thickness 56 (e.g., a total thickness) that is less than a thickness 58 of the liner member 48. For example, the first layer 70 has a thickness 78, the second layer 72 has a thickness 80, and the third layer 74 has a thickness 82. In some embodiments, one or more of the thicknesses 78, 80, and 82 may be equal. In some embodiments, the thicknesses 78, 80, and 82 may be different. For example, the thicknesses 78, 80, and 82 may generally increase in the direction 76. Alternatively, the thicknesses 78, 80, and 82 may generally decrease in the direction 76.

[0054] As shown, each of the layers 70, 72, and 74 extend along the total length 64 of the skirt section 62 of the liner member 48. However, in some embodiments, one or more of the layers 70, 72, and 74 may extend along only a portion of the total length 64, such as less than or equal to 90% of the total length 64, less than or equal to 80% of the total length 64, less than or equal to 70% of the total length 64, less than or equal to 60% of the total length 64, less than or equal to 50% of the total length 64, or less than or equal to 40% of the total length 64. In such embodiments where at least one layer of the layers 70, 72, and 74 do not extend along the entire total length 64, one or more of the other layers 70, 72, or 74 may have an increased thickness 78, 80, or 82.

[0055] FIG. 8 shows an example process 90 for forming the intervening liner member 50 in accordance with the present disclosure. As shown, the process 90 includes, at block 92, providing an intervening liner member 50 having one or more layers. In some embodiments, block 92 may include arranging the layers in order of increasing density, increasing mechanical strength, or both. In some embodiments, providing the intervening liner member 50 may include forming the intervening liner member 50. The intervening liner member 50 may be formed, manufactured, or otherwise applied by a variety of means such as for instance: sheet film, hot dipped, spray coated, pour formed, injection molded into a separate part then pressed as part for charge manufacturing, or formed as part of a multi-material liner whereby a powdered form of the intermediate material would first be pressed followed by subsequent layers of further intermediates or the main liner material. The multiple intermediates may be used such that each successive layer is nearer to the final composition of the liner member 48 and/or a target composition (e.g., a threshold density less than the density of the liner member 48, a threshold mechanical strength less than the mechanical strength of the liner member 48, or both), thereby producing a smoother transition.

[0056] The process 90 also includes, at block 94, providing a liner member to the one or more layers of the intervening liner member 50. In general, block 94 may include coupling the intervening liner member 50 to the second end 54 of the liner member 48. Further, the process 90 includes, at block 96, assembling the shaped charge 20 including the intervening liner member 50. Block 96 may generally include coupling the intervening liner member 50 to the first end of the explosive component 46 and/or providing the intervening liner member 50 into a shaped charge 20.

[0057] Accordingly, the present disclosure relates to techniques for reducing shot-to-shot variation in shaped charges 20. In general, the disclosed techniques include providing an intervening liner member 50 that includes a density and/or mechanical strength in between that of the liner member 48 and the explosive component 46 of the shaped charge 20.

[0058] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

[0059] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as means for (perform)ing (a function) . . . or step for (perform)ing (a function) . . . , it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).