Patent Application
20240384630
Embodiments disclosed herein generally relate to systems and equipment for use in downhole operations. One or more particular embodiments are directed to shaped charges, and methods for their use, in downhole operations such as, but not limited to, frac'ing.
Shaped charges are a type of explosive device that are used to penetrate hard materials by generally focusing an explosive force in a particular direction. The basic concept behind a shaped charge is relatively simple. Namely, an explosive material is shaped into a conical or cylindrical form, with a hollow cavity in the center. When the explosive is detonated, the resulting blast wave is focused by the shape of the device, creating a high-velocity jet of material that can penetrate a variety of materials.
While shaped charges have proven useful, conventional configurations and designs suffer from various shortcomings. For example, it has proven difficult to implement adequate confinement of the explosive effect of shaped charges. Thus, while the shaped charge may be aimed in a particular direction, unacceptable collateral damage may still result. As another example, conventional shaped charges are directly exposed to the environment in which they are employed and as such are vulnerable to damage that may compromise, if not prevent, operation of the shaped charge. Finally, some conventional shaped charges must be oversized to compensate for low explosive efficiency.
In order to describe the manner in which at least some of the advantages and features of one or more embodiments may be obtained, a more particular description of embodiments will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments and are not therefore to be considered to be limiting of the scope of this disclosure, embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings.
Embodiments disclosed herein generally relate to systems and equipment for use in downhole operations. One or more particular embodiments are directed to shaped charges, and methods for their use, in downhole operations such as, but not limited to, frac'ing.
One example embodiment comprises a shaped charge that is overmolded in a material, such as plastic for example, and is encased by a cartridge that may be able to survive the blast of the shaped charge. In an embodiment, the cartridge may be configured as a sacrificial material to protect a barrel. In an embodiment, the cartridge may be configured to propel or fire the overmolded shaped charge.
Embodiments, such as the examples disclosed herein, may be beneficial in a variety of respects. For example, and as will be apparent from the present disclosure, one or more embodiments may provide one or more advantageous and unexpected effects, in any combination, some examples of which are set forth below. It should be noted that such effects are neither intended, nor should be construed, to limit the scope of the claims in any way. It should further be noted that nothing herein should be construed as constituting an essential or indispensable element of any embodiment. Rather, various aspects of the disclosed embodiments may be combined in a variety of ways so as to define yet further embodiments. For example, any element(s) of any embodiment may be combined with any element(s) of any other embodiment, to define still further embodiments. Such further embodiments are considered as being within the scope of this disclosure. As well, none of the embodiments embraced within the scope of this disclosure should be construed as resolving, or being limited to the resolution of, any particular problem(s). Nor should any such embodiments be construed to implement, or be limited to implementation of, any particular technical effect(s) or solution(s). Finally, it is not required that any embodiment implement any of the advantageous and unexpected effects disclosed herein.
Shaped charges date back to the early 19th century when early experiments with explosives began to reveal the potential of shaped charges for industrial applications. One of the earliest documented uses of a shaped charge was in 1883, when a French mining engineer named Henri M. Salleron used a conical shaped charge to bore a hole through a rock face. The success of this experiment led to further developments in shaped charge technology, as engineers and scientists began to explore the potential of this new type of explosive.
The use of shaped charges for oil and gas well perforation began in the 1940s, following their successful deployment in military applications during World War II. The first oil well perforating shaped charges design consisted of a cylindrical explosive charge surrounded by a metal casing. These early designs were only moderately effective, with the resulting perforations often irregular and inefficient. Developments in shaped charges continued in the 1950s and into the 1980s.
Modern shaped charges are widely used in the oil and gas industry to perforate casing and cement barriers in order to access and extract hydrocarbons from reservoirs. An important functions of these shaped charges is their ability to penetrate hard materials with relatively little collateral damage. Because the explosive force is focused in a specific direction, the damage to surrounding structures and materials is often minimal. This makes shaped charges ideal for use in situations where precision and control are critical.
Notwithstanding these advancements in shaped charge technology however, a variety of problems in this field remain unresolved. Examples of these problems are noted above.
Typical components that make up the barrels, carriers, and shaped charges, used for oil and gas well perforation are configured to be used only once. This is due at least in part to the extreme pressures, temperatures, and stresses involved in a typical perforation process.
The shaped charge carrier is a hollow cylindrical tube that houses the shaped charge and provides a path for the explosive jet to penetrate the target formation. The carrier is typically made of a high-strength material, such as steel or copper, and is designed to withstand the high pressure and temperature conditions generated during the firing process. The carrier is usually equipped with a number of features designed to improve the performance and safety of the perforation operation. These features may include safety locks or mechanisms to prevent accidental firing, as well as alignment guides or markers to ensure accurate placement of the carrier and shaped charge. Once the shaped charges are fired, the carrier is destroyed and is not reusable.
The shaped charge barrel is a larger cylindrical tube that houses the shaped charge carrier and provides additional protection and support during the perforation operation. The barrel is typically made of a high-strength material, such as steel or aluminum, and is designed to withstand the extreme pressure and temperature conditions generated during the firing process. The barrel is usually equipped with a number of features designed to improve the performance and safety of the perforation operation. These features may include safety locks or mechanisms to prevent accidental firing, as well as alignment guides or markers to ensure accurate placement of the barrel and carrier. Once the shaped charges are fired, the barrel is destroyed and is not reusable.
The shaped charge is the explosive device at the heart of the perforation operation. The charge is typically made up of a cylindrical explosive charge surrounded by a metal liner, which is shaped into a conical or spherical form to create a focused jet of explosive energy. The explosive charge is usually made up of a high-energy material, such as RDX or HMX, which produces a large amount of pressure and heat when detonated. The liner is typically made of a high-strength material, such as copper or steel, and is designed to rapidly accelerate and shape the explosive energy into a focused jet.
The shaped charge is carefully assembled and tested to ensure maximum performance and safety during the perforation operation. However, due to the extreme pressure and temperature conditions generated during firing, the liner and other components of the shaped charge are typically deformed or damaged beyond repair, rendering the shaped charge unusable for future operations.
Shaped charges used for oil and gas well casing perforation may include several components, each designed to contribute to the overall performance of the device. The main components of a typical oil and gas well casing perforating shaped charge are:
Shaped charge barrels are designed to be used only once in oil and gas perforating operations. This is due to the nature of the perforating process, which subjects the barrel and its associated components to high pressures, temperatures, and stresses that can cause irreversible damage.
During a perforating operation, the shaped charge is fired through the barrel and into the target formation, creating a perforation through the casing and cement barriers. This process generates a large amount of energy in a very short period of time, resulting in extreme pressure and temperature conditions within the barrel and surrounding environment.
The intense pressure and heat generated by the firing process can cause significant deformation and damage to the barrel, liner, detonation mechanism, carrier, and all existing components located inside the gun barrel. In particular, the liner of the shaped charge, which is designed to rapidly accelerate and shape the explosive energy into a focused jet, experiences significant stress and deformation during the firing process. This can cause the liner to crack, deform, or break, rendering the shaped charge ineffective for future perforation operations if a shaped charge next to that specific charge is fired. That explosion may cause irreversible damage to the neighboring shaped charges inside the gun barrel. Gun barrels are typically loaded with 3 or 6 shaped charges on a carrier. That specific system is designed so that all shaped charges inside that barrel are fired simultaneously at once. This is necessary due to the nature of the explosion that occurs inside the gun barrel.
Additionally, the high-pressure shock wave generated by the firing of the shaped charge can cause damage to the barrel and its associated components, including the detonation mechanism and any wiring or electronics used for remote triggering. This damage can result in safety hazards and malfunctions that render the barrel and shaped charge unusable for future operations.
As a result of these factors, shaped charge barrels are typically designed to be used only once and are discarded after each perforation operation. This allows for maximum safety and reliability during subsequent operations, as well as ensuring that the perforating equipment is always in optimal condition for use.
Conventional perforating gun strings that are used in oil and gas today, may consist of multiple gun barrels and each gun barrel may accommodate a carrier, and 3 to 6 shaped charges, and isolation bulkheads between each gun barrel. The isolation bulkhead is required to ensure that when one of the gun barrels shaped charges are fired, the next gun barrel is not flooded or destroyed by the explosion that ensues when the shaped charge is fired.
The concerns regarding shaped charge operations raised in the above discussion may be better appreciated with reference to an example use case for a conventional perforating system. In particular, a stage in a frac'ing operation may require a shaped charge perforating system. That specific stage may require 15-45 perforations be made in the casing and formation. If the stage requires 45 perforations and a non-reusable gun barrel is only to accommodate 6 shaped charges, the required amount of gun barrels would be 8. This would require a bulkhead between each gun barrel. This particular gun string may have a length of 25 to 50 feet. As this example illustrates, the unfired shaped charges in such a string may be vulnerable to damage, and thus rendered nonfunctional, due to their configuration and operation.
One example embodiment comprises a shaped charge that is overmolded in a material, such as plastic for example, and is encased by a cartridge. In an embodiment, an overmolded shaped charge may be used to perforate a casing and a geological formation, or simply ‘formation,’ of oil, gas, and geothermal wells. The overmolded shaped charge configuration may enable shaped charge designs to be more flexible at least with respect to their size and geometry.
An overmolded shaped charge according to one embodiment may possess various useful features and advantages relative to conventional systems, devices, and methods. However, no embodiment is required to possess any of such features and advantages. The following examples are illustrative, but not exhaustive.
In particular, the features and advantages of one or more embodiments may include the following, any one or more of which may be realized when performing operations including, but not limited to, perforating oil, gas, and geothermal, wellbores:
An overmolded shaped charge, according to one embodiment, may be used in a conventional gun string which may include a carrier and a barrel. In one conventional gun string, scallops and/or bands are machined into the outer surface of the barrel. The overmolded shaped charge may be used in various types and configurations of perf guns including, but not limited to:
An overmolded shaped charge according to one embodiment may be used in an interlocking perforating gun. The overmolded shaped charge, and its cartridge that contains it, may be loaded into a barrel, or a receiver of an interlocking perforating gun body. One example configuration is disclosed in
Another benefit, relative to conventional charges and guns, of the overmolded shaped charge, for use in oil, gas, and geothermal applications, is the ability to fire one overmolded shaped charge at a time without damaging the gun, other components located in the gun, or other shaped charges located in the gun. Conventional perforating systems require that all shaped charges located in a given barrel be fired at once. An overmolded shaped charge according to one embodiment may eliminate the need to fire multiple overmolded shaped charges simultaneously. Thus, the overmolded shaped charge in this example embodiment may enable a process in which multiple overmolded shaped charges are fired in some specified sequence.
In an embodiment, an overmolding process comprises a process in which a material is molded onto an existing component or substrate. The existing component, in one or more embodiments, is the shaped charge, and may also comprise other devices that may be included to enhance the performance of the shaped charge.
In an embodiment, an overmolding process may be used to add features, improve functionality, or enhance aesthetics of the shaped charge. Overmolding may be performed using a variety of materials including, but not limited to, thermoplastic elastomers (TPE), thermoplastic polyurethane (TPU), silicone, and other elastomers. Following is a discussion of one example process and procedure, according to an embodiment, for overmolding a shaped charge from manufacturing fixtures, molds, pouring or injecting the over mold material, and finishing the product. Note that as used herein, an ‘overmold’ and ‘overmolding’ process are not intended to be limited for use with any particular overmold material(s).
In one embodiment, the first step in overmolding is designing and preparing the component to be overmolded, such as a shaped charge for example. This may involve, for example, selecting the materials, shapes and geometries, as well as sizes of the shaped charge to fit into the mold where the overmolding will be performed. The shaped charge may be configured with the correct dimensions and tolerances to ensure a good fit in the mold. The shaped charge may also be cleaned and prepared for overmolding. The surface of the shaped charge may be free of any contaminants such as oil or dust. The shaped charge may be overmolded with, or without, the shaped charge loaded between the liner and the case.
In one embodiment, the second step of an example overmolding process comprises designing and fabricating the mold in which the component will be placed for overmolding. The mold may be configured to accommodate the shaped charge and the overmolding material. The mold may be made from a durable material such as steel or aluminum. The mold may also comprise features such as ejector pins and venting to ensure proper molding, and removal of the overmolded item from the mold.
In one embodiment, after the mold is designed and fabricated, the manufacturing fixtures may be produced to support the mold in the manufacturing process. Fixtures may be used to hold the mold in place during the overmolding process. The fixtures may be configured to ensure that the mold is held securely in place during the injection process.
In one embodiment, the overmolding material may be selected based on the shaped charge properties and requirements. The overmolding material may be chosen based on its hardness, flexibility, and chemical resistance. The overmolding material may be compatible with the substrate material, that is, the material that will be contacted by the overmolding material, to ensure a strong bond between the two materials.
In one embodiment, the overmolding process may comprise injecting the overmolding material into the mold cavity where the object, such as a shaped charge, may be located. In one embodiment, the injection molding process may comprise several operations including, but not limited to:
In one embodiment, the final step in an overmolding process comprises finishing the product. Finishing may involve, for example, removing any excess material, such as flash, from the now overmolded shaped charge and ensuring that the overmolded shaped charge meets the required specifications. The finishing process may include trimming, sanding, or polishing the overmold portion of the overmolded shaped charge
In other example embodiments, variations of an overmolding process may be employed, including insert molding and two-shot molding. Some example processes are discussed below.
Insert molding is a process in which a component or substrate, such as a shaped charge for example, is placed into the mold before the overmolding material is injected. The existing component, in this case, is the shaped charge and other devices that may be included to enhance the performance of the shaped charge. The overmolding material is then injected or otherwise introduced into the mold, bonding with the shaped charge material to create a single, overmolded, component.
In one embodiment, an insert molding process may comprise the following operations:
In an embodiment, two-shot molding is a process in which two different materials are injected into a mold to create a single component that includes an overmold comprising the two different materials. In one embodiment, a first material is injected into the mold to create a first overmold as the substrate or base component for a subsequent overmold. The second material is then injected into the mold to overmold the first overmold, creating a single component with two different materials, one of which is overmolded over the other so that at least a portion of the overmold comprises two layers. This process may include techniques from both processes, insert molding and two-shot molding.
Thus, in an embodiment, a component such as a shaped charge may be inserted into a mold. The first material may be injected into the mold and bonded to the shaped charge. The second material may then be injected into the mold and bonded to the first injected material. This may be done to enable inclusion of other components such as fuses, electrical devices and mechanisms, nanotechnology, tracers, combustible materials, and other materials, devices, and mechanisms that may be used to enhance the performance of the shaped charge, gather and record data, or increase reliability, efficiency, and durability of the overall component. In particular, such components may reside on or near the first material so that they are covered or enclosed/encased in part, or entirely, by the second shot of material.
In one embodiment, a two-shot molding process comprises the following operations:
Other overmolding processes that may be employed in an embodiment for overmolding a shaped charge may include, but are not limited to:
The use of an overmolding process, and overmold, in one or more embodiments may present various advantages. Some examples of such advantages are discussed below. In an embodiment, some advantages of overmolding may include, but are not limited to:
In an embodiment, one or more materials may be used to overmold a component such as a shaped charge. The materials may form discrete overmold layers that are layered one over the other, or the materials may be partly or completely blended together before, and/or during, an overmolding process. An embodiment may comprise a first overmold layer made of a first material, and a second overmold layer layered over the first overmold layer and comprising a second material that is the same as, or different from, the first material. Some example materials that may be employed when overmolding a shaped charge include, but are not limited to: Liquid Crystal Polymer (LCP); Polyetherimide (PEI); Polyphenylene Sulfide (PPS); Polyetheretherketone (PEEK); Polyimide (PI); Thermoplastic Polyurethane (TPU); Polysulfone (PSU); Liquid Silicone Rubber (LSR); Polyamideimide (PAI); Polyarylsulfone (PAS); Polyetherketone (PEK); Polybenzimidazole (PBI); Polyamide (PA); Acetal (POM); and Polycarbonate (PC).
Example combustible materials that may be employed when overmolding a shaped charge include, but are not limited to:
Following is a discussion of one or more example embodiments disclosed in the figures. These embodiments, and this discussion, are presented only by way of example, and are not intended to limit the scope of the invention in any way.
With reference first to
For example, the overmolded shaped charge 100 may comprise a liner 101. In one embodiment, the liner 101 is located above a shaped charge 102 and, depending on the material choice for the liner 101, the liner 101 may be pressed, welded, fused, or pressed into the case 103 that contains the shaped charge 102.
One purpose of the liner 101 is to form and direct the high explosive energy of the shaped charge 102 into a focused, high-velocity metal jet. The liner 101 is configured and arranged to collapse inward under the detonation pressure of the explosive, or charge. As the liner 101 collapses, it forms a high-velocity jet of metal that penetrates the target 120 material. In more detail, an embodiment comprises a single jet. The liner forms the cone geometry and as the shaped charge 102 is fired, the liner 101 will melt and turn into a plasma in the form of a metal jet.
The shape of the liner 101 may vary from a simple conical shape to more complex shapes such as, but not limited to, an ellipse, ogive, bi-conical, double cone, trumpet, or hyperbolic shape. The shape of the liner 101 may also determine the jet velocity and penetration depth. For example, a cone-shaped liner 101 according to one embodiment may produce a more focused jet with higher velocity and deeper penetration, while an ogive-shaped liner 101, for example, produces a wider, less focused jet with lower velocity and shallower penetration.
The liner 101 performance may depend on its material properties, thickness, shape, and velocity. The liner 101 material may have a high density and strength to withstand the detonation pressure and to promote uniformity in its inward collapse. The thickness of the liner 101 determines the jet velocity and penetration depth. In general, thicker liners 101 may create slower jets but deeper penetration, while relatively thinner liners 101 create faster jets but shallower penetration.
Different liner 101 geometries for a shaped charge 102 may provide benefits such as improved penetration, increased cutting ability, and reduced collateral damage. The shape and size of the hole, or perforation, created by the shaped charge 102 may also be influenced by the liner 101 geometry, with certain designs producing specific types of holes that may be desired for certain applications. Additionally, different liner 101 geometries can affect the formation and behavior of the jet that is created upon detonation, which can impact the overall performance and effectiveness of the shaped charge 102.
There are several different methods that may be used to manufacture liners 101 for shaped charges 102. The choice of method may depend, for example, on the liner 101 material, its properties, and the desired liner 101 shape. Following are some example methods that may be used to manufacture liners 101 for shaped charges 102.
A liner 101 according to an embodiment may comprise various materials. Some examples of such materials are discussed below.
Example liner materials include, but are not limited to:
In the example of
A shaped charge 102 according to one embodiment may comprise various materials. Some examples of such material include, but are not limited the following.
Various methods may be used to load a shaped charge 102 into a shaped charge assembly 100. For example, the shaped charge 102 may be loaded into the shaped charge assembly 100 from the rear through the cartridge base 109, an embodiment of which is discussed below. In an embodiment, this loading process may comprise pouring of a powder, crystalline, or liquid form, of charge material(s) into the case 103 with the liner 101 acting as the seal. The charge materials, which becomes the shaped charge 102, may be poured through the area where the detonator stem 108 resides. The pour may be done before installing the detonator 104 and detonator stem 108 in the shaped charge assembly 100. This process may be performed when the liner is already seated into the case and the shaped charge 102 is already overmolded, or not overmolded, depending on the embodiment.
In another loading method, the charge may be introduced from a top of the cartridge wall 105 before the liner 101 is seated to the case 103. In an embodiment, this loading process may be performed as part of an overmolding process such as hybrid overmolding. In a hybrid overmolding process, the charge, which may comprise powder, may be poured into the case 103, and the liner 101 pressed and seated to the case 103, a burst disk may be installed, and then the shaped charge 102, cooperatively formed by the liner 101 and case 103, overmolded. When performing a hybrid overmold process according to one embodiment, the shaped charge 102 may be overmolded up to the top of the case 103, the charge then poured in, the liner 101 pressed and seated to the case 103, a burst disk installed, and then the rest of the shaped charge 102 overmolded to the top.
With continued reference to the example of
The case 103, according to one embodiment, may have various features and serve several purposes. For example, the case 103 case contains the explosive shaped charge 102 and directs the energy of the explosion of the shaped charge 102 towards the liner 101.
As another example, the geometry of the case 103 may define, or help to define, the shape of a jet. In particular, the case 103 may comprise a specific shape. From a top down view, the shape of the overmolded shaped charge 100, including the case 103, may be elliptical, triangular, perfect circle, square, and/or rectangular, for example. The shape of the jet may match the shape of the case 103. The shape of the case 103 may also control the direction and velocity of the metal jet as it penetrates the target 120.
An embodiment of the case 103 may also implement a containment function. For example, the shaped charge 102 may be highly sensitive such that it can be easily detonated by shock, heat, or friction. The case 103 may provide a protective barrier around the shaped charge 102, which helps to prevent accidental detonation and also ensures that the explosive energy of the shaped charge 102 is directed towards the target 120. As well, the case 103 may provide a stable platform for the shaped charge 102 to be mounted on, and may also help to maintain the integrity of the shaped charge 102 during transportation and storage. Further, the case 103 may help to align the shaped charge 102 with the target 120 and also ensures that the shaped charge 102 is oriented in the correct position for maximum effectiveness. In one embodiment, the case 103 may comprise fins or other features that help to stabilize the shaped charge 102 in flight and also ensure that the jet is directed towards the target 120.
In an embodiment, the case 103 may be configured to be compatible with different launch systems. These launch systems may include, but are not limited to, downhole perforation systems.
An embodiment of the case 103 may be manufactured using a variety of different processes. One of these processes is metal casting, which may involve melting the metal and then pouring the molten metal into a mold that has the desired shape. Once the metal has cooled and solidified, the mold is removed, and the case 103 may be finished through additional machining and polishing processes.
A metal spinning process may be used to produce a case 103. Metal spinning is a process that involves rotating a metal disc on a lathe and shaping the rotating metal disc using specialized tools. This process may be used to make lightweight, high-strength shaped charge cases 103 from materials such as aluminum, for example.
An embodiment of a case 103 may be produced using an injection molding process to make a plastic case 103. An example injection molding process involves melting plastic pellets and injecting them into a mold that has the desired shape of the case 103. Once the plastic has cooled and solidified, the mold is removed, and the case 103 may be finished through additional polishing, trimming, and/or painting, processes.
A composite layup process may be used to produce an embodiment of a case 103. Such a process may be used to make a case 103 from composite materials such as fiberglass or carbon fiber. One example of this process involves layering sheets of composite material over a mold that has the desired shape of the case 103, and then using heat and pressure to bond the layers together. Once the composite material has cured, the mold is removed, and the case 103 may be finished through additional machining and polishing processes.
In an embodiment, machining processes may be used to produce a case 103. Such machining processes may involve the removal of material from a block or sheet of metal or composite material to create a case 103 with a desired shape and size.
As a final example, an additive manufacturing process may be use to produce an embodiment of a case 103. For example, 3D printing metal, also known as metal additive manufacturing, is a process that uses various technologies to create three-dimensional metal parts or objects from a digital model. This 3D printing process comprises layer-by-layer deposition of metal powder or wire using techniques such as selective laser melting (SLM), electron beam melting (EBM), or binder jetting. This process enables production of complex geometries, customization, and reduced waste compared to conventional metal manufacturing methods.
A variety of different materials may be used to produce a case 103 according to one embodiment. One of such materials is steel, which has high strength, durability, and resistance to high temperatures. Steel cases 103 can be made to withstand the intense pressure and heat generated by the shaped charge 102. Another example case 103 material is aluminum, which is a lightweight material and is not as strong as steel, but is still able to withstand the pressure and heat generated by the explosive charge. An embodiment of a case 103 may be made of plastic, or of composite materials such as fiberglass or carbon fiber. These composite materials may be used to make cases that are both lightweight and strong. In an embodiment, a case 103 may be made of ceramic materials, such as boron carbide or aluminum oxide. A case 103 of one or more of these materials may be highly resistant to heat and abrasion. In an embodiment, a case 103 may be made of brass. Still another embodiment of a case 103 may be made of nickel-based alloys, such as the alloys respectively sold under the marks Inconel® and Monel®, which offer good strength and toughness at high temperatures and under extreme conditions. An embodiment of a case 103 may be made of titanium, which is lightweight, strong, and has good corrosion resistance. As a final example, a case 103 may be made of various alloys containing molybdenum and vanadium, which are often added to alloy steels to improve their properties, such as strength, toughness, and wear resistance.
In an embodiment, the detonator 104, an example of which is disclosed in
Among other things, the detonator 104 serves to initiate the explosive reaction of the shaped charge 102 and create the high-velocity jet of molten metal. The detonator 104 may be, for example, a small, high-explosive charge that detonates with high speed and accuracy when activated. The detonator 104 may comprise an electrical detonator, bridge wire, primer, resistor, or any detonation device capable of igniting the selected shaped charge 102.
When the detonator 104 is triggered, it transmits a shockwave that travels through the charge 102. This shockwave compresses and heats the explosive material of the shaped charge 102, causing the shaped charge 102 to rapidly explode and release a large amount of energy in the form of heat and one or more gases. As the shaped charge 102 explodes, it creates a high-pressure wave that travels toward the base of the shaped charge 102. This pressure wave causes the liner 101 to collapse inward and form a highly focused jet of molten metal that travels at high speed toward the target 120.
In an embodiment, the detonator 104 may be activated by an electrical signal, which is transmitted through a wire or other conductor that is connected to the detonator 104. The electrical signal may also be generated by a variety of sources, including a timer, a remote-control device, or a sensor that detects the presence of a target 120.
In an embodiment, and with reference to
In an embodiment, the cartridge wall 105 may also act as a secondary barrel. In its role as a secondary barrel, the cartridge wall 105 material may be sacrificial, or may survive the charge 102 detonation without material damage. Overall, the cartridge wall 105 may be configured to increase the performance of the shaped charge 102 by having the plastic overmold 106 material contained as a buffer between the cartridge wall 105 and the case 103 during the explosion that is generated when the shaped charge 102 is ignited. Depending on the design and material, the cartridge wall 105 may survive the blast, such that the cartridge may be reusable, or able to have another shaped charge 102 overmolded into it.
In another embodiment, the cartridge wall 105 may comprise a sacrificial element that acts as a buffer and increase the performance of the shaped charge 102 by absorbing the energy of the blast and creating a more focused jet and explosion. The cartridge wall 105, based on the material selection and the overmold 106 thickness and material, may not survive the blast, but may absorb enough of the explosion and energy that the barrel of the system firing it, survives and is not damaged in any material way.
In one embodiment, the cartridge wall 105 may be omitted, and the overmolded shaped charge 102 may be inserted directly into a barrel of a perf gun, such as an interlocking perf gun for example. However, no particular type of perf gun is necessarily required in any embodiment.
A variety of different materials may be used for various embodiments of a cartridge wall 105. For example, various types of brass materials may be used for a cartridge wall 105, an example brass materials include, but are not limited to, alpha brass, beta brass, cartridge brass, naval brass, red brass, yellow brass, and dezincification-resistant brass. An embodiment of a cartridge wall 105 may comprise various aluminum materials such as, but not limited to, 1xxx Series, 2xxx Series (2024 aluminum for example), 3xxx Series (3003 aluminum for example), 4xxx Series (4043 aluminum for example), 5xxx Series (5052 aluminum for example), 6xxx Series (6061 aluminum for example), and 7xxx Series (7075 aluminum for example). Other example materials for an embodiment of a cartridge wall 105 include, but are not limited to, magnesium alloys, titanium alloys, nickel alloys, copper alloys including CuZn37 and CuZn36Mn2Al2Fe1-C, high-strength low-alloy (HSLA) steels, armor grade steels including steels conforming to MIL-A-46100 and MIL-A-12560, stainless steels including 17-4 PH and 15-5 PH, and tool steels including H13 and D2.
An overmold 106 according to one embodiment is disclosed in
In an embodiment, the overmold 106 may provide one or more benefits with regard to the configuration and/or operation of the shaped charge 102. For example, the size and geometry of the overmold 106 may increase the efficiency of the formation of the jet, by ensuring a consistent stand-off distance between the charge 102 and a target 120, and alignment of the shaped charge 102 with the target 120.
As another example, the size and geometry of an embodiment of the overmold 106 may contain the energy created by the explosion of the charge 102. This containment may in turn increase the efficiency, consistency, and the performance of the jet by partly containing or confining the energy of the jet in such a way that the energy may be focused and directed.
An embodiment of the overmold 106 may enable significant flexibility in the design and/or use of an embodiment of the shaped charge 102, as noted in the following examples. An embodiment of the overmold 106 may eliminate the need for a gun tube with scallops, bands, and may eliminate the need to shoot through an alloy gun tube before contacting the target 120. In an embodiment, an overmolded shaped charge 102 may not need to be housed inside of a gun tube for use. Rather, the overmolded shaped charge 102 may be assembled and aligned with barrels in an interlocking perforating gun, or may be used in a gun tube that may have the ability to chamber the cartridge of the shaped charge 102 and expose the shaped charge 102 to the wellbore.
As another example, an embodiment of the overmold 106 may reduce, or eliminate, stand-off concerns and enable the liner 101 the necessary space to form the jet without the jet contacting metal before hitting the target 120. This enables flexibility in terms of the geometries and shapes to be employed for the liner 101.
Further, an embodiment of the overmold 106 provide a containment function. Specifically, the overmold 106 may contain a shaped charge assembly 100 which may comprise the liner 101, charge 102, case 103, bulkhead 107, burst disk 121, detonator 104, and electrical wiring 111. The overmold 106 may also contain other devices such as tracers, data collection devices such as nanobots, and combustible materials such as zirconium.
An embodiment of the overmold 106 may act as a sealing mechanism. The sealing may seal off contaminant, such as water, from the shaped charge 102 as well as from electrical devices that are susceptible to damage by water.
As a final example, an embodiment of the overmold 106 may provide protection against energy generated by ignition or detonation of the charge 102. In particular, when the charge 102 is ignited and the explosion takes place inside the case 102, a large amount of energy may be generated that can expand the case 103 outward and towards the cartridge. In an embodiment, the overmold 106 may be configured, and have the material characteristics, to absorb some of the energy generated from the explosion.
There are various standoff considerations that may apply in a downhole environment and process. These stand-off considerations may imply various concerns that may be resolved, in whole or in part, by an embodiment of the overmold 106.
In general, shaped charges are typically designed to operate at a specific optimal standoff distance. This distance is determined through extensive testing and engineering analysis to achieve the best penetration and jet formation characteristics. Deviating significantly from the optimal standoff distance may result in reduced performance.
The standoff distance can influence the penetration depth of the shaped charge 102, specifically, the jet produced by the shaped charge 102. In general, increasing the standoff distance tends to increase the penetration depth, up to a certain point. Beyond that point, increasing the standoff distance may cause the jet to disperse and experience a loss of effectiveness.
The standoff distance affects the formation and focusing of the shaped charge 102 jet. The jet is a high-velocity, high-pressure stream of molten metal that penetrates the target 120. The optimal standoff distance is chosen to achieve a well-formed and focused jet for maximum penetration.
The standoff distance requirements may vary depending on the type and properties of the target 120 material. Harder materials may require smaller standoff distances to achieve effective penetration, while softer materials may enable the use of larger standoff distances. In an embodiment, the jet produced by the overmolded shaped charge 102 first contacts the casing 103, but in an embodiment, the jet does not have to shoot through a layer of material in a gun tube/barrel, as would be the case with a standard shaped charge perforating gun which requires that the jet pass through the structure of the perforating gun before the jet hits the target 120. Thus, an embodiment may enable the shaped charge 102 to be moved relatively closer to the target 120, or further away from the target 120. Thus, in an embodiment, the location of the shaped charge 102 is not limited to one particular standoff distance, as is the case in a conventional perforating gun shooting a conventional shaped charge. Rather, an embodiment of the overmolded shaped charge 102 may be set, using variations in the overmold 106 geometry, at various standoff distances from the target 120, at least because the shaped charge 102 is overmolded and exposed, or may be, directly to the wellbore environment.
In an embodiment, an overmold 106 may comprise a polymer, plastic, or resin material that may be injected directly into a mold that houses the shaped charge 102 and other devices that may be contained within the shaped charge 102 or overmold 106. In an embodiment, the cartridge may comprise the mold for the overmold material. As noted elsewhere herein, the cartridge may comprise the cartridge wall 105, and the cartridge base 109. Some example over mold materials are discussed below.
One embodiment of an overmold 106 may comprise one or more materials from the resin family of amorphous thermoplastic polyetherimide (PEI) materials sold under the mark ULTEM™ 1000. This resin family is part of the polyetherimide (PEI) family of materials. Following are some example properties of this resin family.
In another example embodiment, an overmold 106 may be made of glass-filled PTFE. Polytetrafluoroethylene (PTFE) is a fluoropolymer, which may be sold under the mark TEFLON®, that has excellent chemical resistance, low friction coefficient, and non-stick properties. However, PTFE has limited strength and can deform under pressure or high-temperature conditions. To improve its strength and temperature resistance, glass fibers may be infused into the PTFE matrix, resulting in a composite material known as glass-filled PTFE. One example glass-filled PTFE combination may contain a high percentage of glass fibers, such as in the range of 25% to 30% by weight, with a specific glass fiber length and diameter that optimize the mechanical properties of the glass-filled PTFE. In an embodiment, the glass fibers provide a reinforcing effect that improves the tensile and compressive strength, stiffness, and resistance to deformation under pressure, of the glass-filled PTFE. Additionally, the glass fibers have a high thermal conductivity, which helps to dissipate heat from the glass-filled PTFE, improving its temperature resistance. Finally, the glass-filled PTFE also has a low coefficient of thermal expansion, making it less susceptible to dimensional changes under varying temperature conditions. Glass-filled PTFE includes excellent chemical resistance, non-stick properties, and a low friction coefficient. In an embodiment, the overmold 106 may comprise polycarbonate. An overmolding process that utilizes polycarbonate as one of, or the only, layer(s) of an overmold 106 may be the same as, or similar to, the overmolding process using PEI materials, and/or the overmolding process using glass-filled PTFE.
Overmolding is a process that involves molding, in one embodiment, a thermoplastic material, such as a PEI material for example, over a component, or components, such as, but not limited to, an electronic component, shaped charge, detonator, bulkhead, and/or other devices. In one example embodiment, an overmold process may comprise the following four operations.
In one embodiment, the first operation of an overmolding process may comprise designing the mold for the overmolded part, taking into account the shape and size of the shaped charge 102, the desired thickness and shape of the overmold 106 to be created, and any other design requirements. Once the mold is designed, it is manufactured using, for example, precision machining techniques.
In an embodiment, the second operation comprises pre-treatment of the shaped charge and other devices. For example, before overmolding, the shaped charge 102 must be properly prepared to ensure proper adhesion between the shaped charge 102 and the overmold 106 material(s). This preparation may involve cleaning, degreasing, or other surface preparation techniques, depending on the nature of the shaped charge and other devices.
In an embodiment, the third operation comprises forming the overmold 106 by injection molding. In one embodiment, this operation may comprise injection molding of ULTEM™ 1000 over the shaped charge 102 using the prepared mold. This process may comprise melting the thermoplastic material, injecting the melted thermoplastic material into the mold cavity, and then cooling and solidifying the thermoplastic material to form the overmolded shaped charge 102. In one embodiment, this process of injection molding may be repeated several times to achieve the desired thickness and shape of the overmold 106.
In an embodiment, the final operation of an overmolding process comprises post-molding processing. For example, once the overmolded shaped charge 102 is formed, any excess material may be removed using trimming or other post-molding processing techniques. The finished overmold 106 and/or other elements of the overmolded shaped charge 102 may also undergo additional finishing steps, such as polishing or painting, depending on the desired final appearance and functionality.
In an embodiment, an overmolding process may be performed using glass-filled PTFE. This overmolding process for glass-filled PTFE may comprise two, or more, separate injection molding operations. Except as noted below, the overmolding process for glass-filled PTFE may be similar, or identical, to the overmolding process for PEI materials such as ULTEM™1000. For example, during the overmolding process, the glass-filled PTFE is melted and injected into the mold over the shaped charge and other devices. The glass in the glass-filled PTFE material may improve the strength and durability of that material, relative to a PTFE material that does not include glass. The overmolding process can be used to create a product that is both strong and durable, with the ability to withstand a range of different conditions.
After the mold has been designed and produced for use in an overmolding process for glass-filled PTFE, and the shaped charge 102 prepared, a first overmold material, which may comprise any of the disclosed overmold material(s), is injected into the mold and flows around the electronics, shaped charge, detonator, bulkhead, and other devices, creating a solid overmold 106.
The mold is then cooled to solidify the first overmold material over the shaped charge 102. Next, the second overmold material, which may comprise glass-infused PTFE, is injected into the mold over the first material. The mold is then cooled to solidify the second material. Finally, the overmolded part is removed from the mold and any excess material is trimmed off or otherwise removed.
As shown in the example of
For example, a bulkhead 107 that is positioned below the shaped charge 102, and houses the detonator 104 and wiring 111 may provide a physical barrier between the shaped charge 102 and the rest of the cartridge and system. This arrangement may help to contain the explosion and prevent it from damaging other components or causing unintended collateral damage.
An embodiment of the bulkhead 107 may serve as a mounting point and/or housing for the detonator 104. By securing the detonator 104 in a fixed position below the shaped charge 102, the bulkhead 107 may help to ensure that the shockwave from the detonator 104 is directed into the shaped charge 102 in a consistent and controlled manner. The bulkhead 107 may, in an embodiment provide additional structural support to the shaped charge assembly 100 as a whole. By reinforcing the area below the shaped charge 102, the bulkhead 107 may help to prevent the cartridge from becoming deformed or damaged during use. In an embodiment, the bulkhead 107 may be configured as part of the cartridge base 109, such that the bulkhead 107 and the cartridge base 109 together form a single part, instead of two or more.
In an embodiment, a detonator stem 108, as disclosed in
In one or more embodiments, an overmolded detonator stem 108 may encapsulate a variety of components. Such components may include, but are not limited to electric detonators; non-electric detonators, such as may be used in situations where electricity is not available or safe to use, that rely on a chemical reaction to initiate the detonation; shock tubes; safety fuses; pyrotechnic initiators; laser detonators; primers; and, det cord. Further details concerning each of these components is set forth below.
In general, shock tubes are thin tubes filled with a shock-sensitive explosive that are used to transmit a shock wave to the shaped charge. Shock tubes are often used in applications where electrical devices are not safe to use, such as in explosive environments. Safety fuses are simple detonation devices used in situations where no electrical or mechanical devices are available. A safety fuse is a length of cord filled with black powder that burns at a consistent rate, allowing for precise timing of the detonation. Pyrotechnic initiators may be small, self-contained devices that contain a pyrotechnic composition. They are often used in situations where a small and reliable detonation device is required. Laser detonators use a laser to initiate the detonation of the shaped charge 102. They may be used when extreme precision is required. Primers include mechanical or electrical ignition devices that comprise a small explosive charge that is used to initiate the detonation. Finally, det cord may comprise a flexible plastic tube filled with a high explosive material that is sensitive to shock, friction, and heat. When ignited, the det cord burns rapidly, generating a shock wave that is transmitted to the shaped charge 102, causing it to detonate.
A cartridge base 109 may, in one embodiment, may form the foundation of an entire overmolded shaped charge 102. The cartridge base 109 is located the rear, or very bottom, of the shaped charge assembly 100, that may be configured to interface with or contain a bulkhead 107, and may include the cartridge wall(s) 105 that contain the overmold 106 and shaped charge 102, and may include a rim that is configured as a chambering ledge for the shaped charge assembly 100 when the shaped charge assembly 100 is inserted into a barrel.
In an embodiment, the cartridge base 109 may perform one or more functions. For example, the cartridge base 109 may provide a surface for the wiring 111, detonator stem 108, and detonator 104. In particular, the base of the cartridge based 109 may comprise a small pocket or recess where the detonator 104, or other detonation devices, may be inserted, or the wiring 111 and detonator stem 108 may be housed.
As another example, an embodiment of the cartridge base 109 may server to the cartridge, that is, the shaped charge assembly 100 and 150: The cartridge base 109 is configured to create a gas-tight seal when it is inserted into a chamber of a perf gun or other device. This seal prevents gases from escaping when the shaped charge 102 is fired, which helps to increase the efficiency of the shot.
In an embodiment, the cartridge base 109 may also act as a secondary bulkhead. This configuration may increase the performance of the shaped charge 102 by creating more rigidity when the charge is ignited.
In an embodiment, the cartridge rim 110 may be located at the very bottom of the shaped charge assembly 100 or 150, below the cartridge base 109, and may act as a landing edge for the shaped charge assembly 100 or 150 to be chambered into a barrel for use. The cartridge rim 110 may be integral with the cartridge base 109 and may enable, for example, extraction of the shaped charge assembly 100 or 150 from the barrel after firing.
In more detail, after the shaped charge 102 is fired, the spent shaped charge assembly 100 or 150 must be extracted from the chamber, or barrel, before another shaped charge assembly can be loaded. The cartridge rim 110 is configured and arranged to provide a protruding element for an extractor to grip, so that the extractor can remove the spent shaped charge assembly from the chamber, or barrel. Further, when loading the shaped charge assembly into a gun barrel, the cartridge rim 110 may act as a guide and stopping mechanism when the shaped charge assembly is loaded into the barrel.
In an embodiment, the wiring 111, see
For example, a LIDAR, or other imaging device may be embedded in, or otherwise contained within, the overmold 106 for viewing the target 120 before the shaped charge 102 is fired. Imaging, such as LiDAR, may also be used to measure the distance to the target 120 and analyze the overall surface of the target 120. Temperature sensors may be positioned in the overmold 106 to record and monitor the overall temperature of the shaped charge 102. A voltage detection sensor may be used to ensure that a live circuit still exists with the shaped charge 102, after a different shaped charge 102 is fired. This detection device may ensure that the shaped charges 102 still have voltage, are live, and have survived the shock and vibration that may occur when one or more other shaped charges 102 in the system are fired. TOF sensors may use ultrasonic or acoustic waves to determine the distance to a target 120. Acoustic microscopy sensors may use ultrasound to create high-resolution images of materials, including those that are opaque or have multiple layers. This sensor may be used to analyze the target 120 and the materials, void spaces, or organic matter that may be behind the first layer of the target 120. Ultrasonic phased array sensors may comprise multiple ultrasonic transducers to steer and focus sound waves in specific directions, allowing for precise imaging of complex structures and materials in downhole locations. This sensor could be used to analyze the target 120 and the materials, void spaces, or organic matter that may be behind the first layer of the target 120. X-ray microcomputed tomography (micro-CT) sensors may use X-rays to create high-resolution 3D images of materials, including those with multiple layers and complex internal structures. Finally, acoustic emission sensors may detect high-frequency sound waves that are emitted from materials under stress or deformation.
As shown, for example, in
The burst disk may be a sacrificial element that comprises, for example, a dome-shaped configuration, as shown in
For example, in high pressure environments, such as subsea, or subterranean/downhole oil and gas, external pressure would collapse the void space 112 without the burst disk 121 present. Thus, the burst disk 121 may preserve the integrity of the void space 121 from collapsing under extreme pressures. In an embodiment, a burst disk 121 may be installed into the overmolded shaped charge 102, above the liner 101, to accommodate adequate stand-off distance from the liner 101 to the target 120. In one embodiment, the burst disk 121 may be made of a material that may have the ability to turn into a jet itself when the liner 121 jet contacts it. This would increase the power potential and performance of the overmolded shaped charge.
Using a burst disk 121 that is installed above the shaped charge 102 may enhance the shaped charge 102 performance. For example, this configuration may enable the burst disk 121 to become a jet of molten metal itself and create a larger hole diameter than the hole created by the jet produced by the liner 121 of the shaped charge 102. As another example, the burst disk 121 may turn into a jet itself and create a hole geometry that may allow a standard cone shaped liner 101 to create a hole that may or may not be a circle or perfectly round, but an elliptical, square, or triangular shaped hole in the target 120.
Various materials may be used for the production of a burst disk 121. Such materials may include, but are not limited to, copper, titanium, ceramic, composite, aluminum, tungsten, copper-nickel, copper-zinc, copper-lead, copper magnesium, and zirconium, and combinations and alloys of any of these.
The example barrel 113 disclosed in
In an embodiment, a barrel 113 may perform various functions. Such functions include, for example, enclosing the cartridge walls 105, guiding the shaped charge assembly, ensuring survivability of the gun system after the overmolded shaped charge 102 is fired, acting as a secondary pressure chamber that ensures efficient performance of the overmolded shaped charge 102 by acting as a rigid member to focus the jet and energy in the direction of the explosion, chambering the overmolded shaped charge assembly, and stabilizing the overmolded shaped charge assembly when the shaped charge 102 is fired or ignited.
According to one example embodiment, an Interlocking Perforating Gun (IPG) Body 1 (114), disclosed in
In an embodiment, IPG Body 2 (115), disclosed in
In an embodiment, the wire tray 116 in IPG Body 1 (114), as shown in
The wire tray 117 in IPG Body 2 (115), as shown in
IPG Body 2 (115) barrel 118 in
As shown in the example of
In an embodiment, a target 120 may comprise a steel pipe or casing. However, the scope of this disclosure is not limited to targets 120 that comprise pipe or casing.
As noted earlier,
In an embodiment, the shaped charge assembly 150 comprises an overmolded shaped charge 102 that can be propelled, by firing out of a cartridge and or barrel. One embodiment of the shaped charge assembly 150 comprises a shaped charge 102, fuses, overmold 106 material, combustible materials, a shield, a cartridge, and mechanical or electrical ignition devices and or detonators 104. The shaped charge assembly 150 may be shot out of a barrel at a target 120 and on impact, ignite the shaped charge 102 located inside the shaped charge assembly 150, creating a jet out of a liner 101, and penetrating the target 120 that it impacted.
In the particular embodiment of
In an embodiment, the detonator 104′ disclosed in
In an embodiment, the cartridge wall 106′ disclosed in
The cartridge walls 105′ disclosed in
In an embodiment, the overmold 106′ disclosed in
In an embodiment, the cartridge base 109′ disclosed in
In an embodiment, the cartridge rim 110′ disclosed in
As disclosed in the example of
Example primers 122 that may be employed in the example shaped charge assembly 150 include, but are not limited to, Percussion Primers, centerfire primers, boxer primers, berdan primers, and electric primers. Percussion primers may comprise a small metal cup that contains a volatile compound such as fulminate of mercury. When struck by a firing pin or hammer, the compound ignites and ignites the propellant. Rimfire primers are a type of percussion primer that are used in rimfire cartridges. In these primers, the volatile compound is contained in the rim of the cartridge case. When the firing pin strikes the rim, the compound ignites and ignites the propellant in the cartridge. Centerfire primers consist of a volatile compound that is contained in the center of the cartridge case. Boxer primers are a type of centerfire primer that have a single flash hole in the center of the primer cup. Berdan primers have multiple flash holes around the primer cup. Electric primers use an electrical charge to ignite a small amount of explosive material.
The example shaped charge assembly 150 may comprise a booster 123. The booster 123 may comprise a combustible material that is the first material ignited by the primer 122. The booster 123, once ignited by the primer 122, will create additional energy that may be transferred into the propellant 124, igniting it at a faster rate, and then propelling the overmolded shaped charge 102. A variety of different materials may be used to produce the booster 123 including, for example, lead styphnate, tetrazene, barium nitrate, lead azide, and mercury fulminate. Lead styphnate is a highly sensitive, low-temperature explosive that can be easily initiated by impact or heat. Tetrazene is a high-performance booster material. Barium nitrate is low-sensitivity booster material. Lead azide is a highly sensitive booster material. Mercury fulminate is a low-sensitivity booster material.
The example shaped charge assembly 150 disclosed in
The example shaped charge assembly 150 disclosed in
Embodiments may employ various different types of timed fuses 125. Examples of timed fuses 125 that may be employed in an embodiment include, but are not limited to, a time pencil fuse, time light fuse, electric time fuse, mechanical time fuse, and a percussion fuse. A time pencil fuse is a type of timed fuse that uses a spring-loaded mechanism to control the burn rate. As the fuse burns, it pulls a spring-loaded striker mechanism back, and when the striker is released, it sets off the detonator. A time light fuse is a type of timed fuse that uses a chemical delay element to control the burn rate. When the fuse is lit, a chemical reaction occurs that produces a flash of light. The time it takes for the flash to occur is used to time the detonation. An electric time fuse is a type of timed fuse that uses an electrical current to trigger the detonator. The current is typically controlled by a timer or other electronic device. A mechanical time fuse is a type of timed fuse that uses a mechanical device, such as a clockwork mechanism, to control the burn rate. When the mechanism runs out of energy, it triggers the detonator. A percussion fuse is activated by a sharp impact and is designed to ignite the explosive charge upon impact. The percussion fuse may ignite the charge within microseconds of the propellant 124 ignition.
The example shaped charge assembly 150 disclosed in
The example shaped charge assembly 150 disclosed in
The example shaped charge assembly 150 disclosed in
The example shaped charge assembly 150 disclosed in
The example shaped charge assembly 150 disclosed in
With attention now to the example of
The Appendix hereto, incorporated in this disclosure in its entirety by this reference, comprises, at pages 1-5, photographs of example shaped charges, according to various embodiments, and their effects when employed, according to one or more embodiments. Pages 6-7 of the Appendix depict conventional perf guns.
The described embodiments are to be considered in all respects only as illustrative and not restrictive. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
| Number | Date | Country | |
|---|---|---|---|
| 63503432 | May 2023 | US |
