BALLISTIC INTERRUPT TO CLOSE A CIRCUIT TO A DETONATOR

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application Ser. No. 63/723,974, entitled “Ballistic Interrupt to Close a Circuit to a Detonator”, which was filed on Nov. 22, 2024, and which is herein incorporated by reference in its entirety for all purposes.

BACKGROUND

The present disclosure generally relates to systems and methods for enabling mechanical actuation of ballistic interrupts to close circuits to detonators.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admission of prior art.

Exploring, drilling, and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. As a result, over the years, well architecture has become more sophisticated where appropriate in order to help enhance access to underground hydrocarbon reserves. For example, as opposed to wells of limited depth, it is not uncommon to find hydrocarbon wells exceeding 30,000 feet in depth. Furthermore, as opposed to remaining entirely vertical, today's hydrocarbon wells often include deviated or horizontal sections aimed at targeting particular underground reserves.

While such well depths and architecture may increase the likelihood of accessing underground hydrocarbon reservoirs, other challenges are presented in terms of well management and the maximization of hydrocarbon recovery from such wells. For example, during the life of a well, a variety of well access applications may be performed within the well with a host of different tools or measurement devices. However, providing downhole access to wells of such challenging architecture may require more than simply dropping a wireline into the well with the applicable tool located at the end thereof. Indeed, a variety of isolating, perforating, and stimulating applications may be employed in conjunction with completions operations.

In the case of perforating, different zones of the well may be outfitted with packers and other hardware, in part for sake of zonal isolation. Thus, wireline or other conveyance may be directed to a given zone and a perforating gun employed to create perforation tunnels through the well casing. Specifically, shaped charges housed within a steel gun may be detonated to form perforations or tunnels into the surrounding formation, ultimately enhancing recovery therefrom.

BRIEF DESCRIPTION

A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

In one embodiment, a perforating gun may include one or more perforating charges and an initiator assembly. The initiator assembly may include one or more detonators configured to cause detonation of the one or more perforating charges. In addition, the initiator assembly may include one or more mechanical components configured to be actuated to transition the initiator assembly from a first mechanical configuration to a second mechanical configuration. A detonation circuit of the initiator assembly is open when the initiator assembly is in the first mechanical configuration to prevent the one or more detonators from detonating the one or more perforating charges and the detonation circuit of the initiator assembly is closed when the initiator assembly is in the second mechanical configuration to enable the one or more detonators to detonate the one or more perforating charges.

In another embodiment, a perforating gun includes one or more perforating charges and an initiator assembly. The initiator assembly may include one or more detonators configured to cause detonation of the one or more perforating charges. In addition, the initiator assembly may include a ballistic interrupt shutter configured to be actuated to transition from a first position to a second position. A detonation circuit of the initiator assembly is open when the ballistic interrupt shutter is in the first position to prevent the one or more detonators from detonating the one or more perforating charges and the detonation circuit of the initiator assembly is closed when the ballistic interrupt shutter is in the second position to enable the one or more detonators to detonate the one or more perforating charges.

In yet another embodiment, a perforating gun includes one or more perforating charges and an initiator assembly having a detonator holder configured to cause detonation of the one or more perforating charges upon transition from a first position to a second position. A detonation circuit of the initiator assembly is open when the detonator holder is in the first position to prevent one or more detonators from detonating the one or more perforating charges and the detonation circuit of the initiator assembly is closed when the detonator holder is in the second position to enable the one or more detonators to detonate the one or more perforating charges.

In yet another embodiment, a perforating gun includes one or more perforating charges and an initiator assembly having a detonating cord configured to cause detonation of the one or more perforating charges upon transition from a first position to a second position. A detonation circuit of the initiator assembly is open when the detonating cord is in the first position to prevent one or more detonators from detonating the one or more perforating charges and the detonation circuit of the initiator assembly is closed when the detonating cord is in the second position to enable the one or more detonators to detonate the one or more perforating charges.

Various refinements of the features noted above may be undertaken in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

FIG. 1 illustrates a perforation operation, in accordance with aspects of the present disclosure;

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

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

FIG. 4 is a side view of a loading tube of a perforation gun, in accordance with aspects of the present disclosure;

FIG. 5 is a cutaway view of a perforation gun, in accordance with aspects of the present disclosure;

FIGS. 6A and 6B illustrate an example initiator assembly with a ballistic interrupt shutter being transitioned from a deactivated position to an activated/released position, in accordance with aspects of the present disclosure;

FIGS. 7A through 7C are various views of an example shutter release mechanism for use in the initiator assembly of FIGS. 6A and 6B, in accordance with aspects of the present disclosure;

FIGS. 8A and 8B are schematic diagrams of an example initiator assembly where the detonator circuit is not completed until a ballistic interrupt shutter has been released, in accordance with aspects of the present disclosure;

FIG. 9 is a schematic diagram of an alternative initiator assembly, in accordance with aspects of the present disclosure;

FIG. 10 is a simplified schematic diagram of another initiator assembly where physical contact between a conductive ballistic interrupt shutter and electrical contacts may be completed, in accordance with aspects of the present disclosure;

FIG. 11 is a simplified schematic diagram of another initiator assembly that includes a delay circuit, in accordance with aspects of the present disclosure;

FIGS. 12A through 12C illustrate various view of an example initiator assembly, in accordance with aspects of the present disclosure;

FIG. 13 illustrates an example initiator assembly having a spring-loaded ballistic interrupt shutter in a first (e.g., deactivated) position and a second (e.g., activated) position, in accordance with aspects of the present disclosure;

FIG. 14 is a graph of nitinol transformation versus temperature for a shape memory alloy (SMA);

FIG. 15 illustrates an example initiator assembly that uses an SMA spring as an arm release mechanism that releases a shutter arm attached to a ballistic interrupt shutter, in accordance with aspects of the present disclosure;

FIGS. 16A and 16B illustrate another example initiator assembly having a reversible shutter drive (e.g., via linear compression) that is powered by an SMA spring, in accordance with aspects of the present disclosure;

FIGS. 17A and 17B illustrate another example initiator assembly having a torsional SMA spring drive, in accordance with aspects of the present disclosure;

FIGS. 18A through 18F illustrate various views of another example, initiator assembly having a linear SMA or solenoid trigger mechanism, in accordance with aspects of the present disclosure;

FIGS. 19A and 19B illustrate another example initiator assembly having a relatively compact SMA or solenoid trigger mechanism, in accordance with aspects of the present disclosure;

FIGS. 20A and 20B illustrate another example initiator assembly having an SMA trigger mechanism that moves from a first (e.g., deactivated) position where an SMA spring is in a relatively non-linear shape to a second (e.g., activated) position where the SMA spring is in a relatively linear shape, in accordance with aspects of the present disclosure;

FIGS. 21A and 21B illustrate another example initiator assembly having a resistor-triggered spring-loaded ballistic interrupt shutter, in accordance with aspects of the present disclosure;

FIGS. 22A and 22B illustrate another example initiator assembly having a resistor-triggered spring-loaded ballistic interrupt shutter, in accordance with aspects of the present disclosure;

FIGS. 23A through 23F illustrate another example initiator assembly having a rotating detonator, in accordance with aspects of the present disclosure;

FIGS. 24A through 24F illustrate another example initiator assembly having a rotating detonator, in accordance with aspects of the present disclosure; and

FIGS. 25A and 25B illustrate another embodiment of an initiator assembly that includes movement of a detonator from a ballistic interrupt position to a non-interrupt position, in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

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.

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.

As used herein, the terms “connect,” “connection,” “connected,” “in connection with,” and “connecting” are used to mean “in direct connection with” or “in connection with via one or more elements”; and the term “set” is used to mean “one element” or “more than one element.” Further, the terms “couple,” “coupling,” “coupled,” “coupled together,” and “coupled with” are used to mean “directly coupled together” or “coupled together via one or more elements.” As used herein, the terms “up” and “down,” “uphole” and “downhole”, “upper” and “lower,” “top” and “bottom,” and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements. Commonly, these terms relate to a reference point as the surface from which drilling operations are initiated as being the top (e.g., uphole or upper) point and the total depth along the drilling axis being the lowest (e.g., downhole or lower) point, whether the well (e.g., wellbore, borehole) is vertical, horizontal or slanted relative to the surface.

In addition, as used herein, the terms “real time”, “real-time”, or “substantially real time” may be used interchangeably and are intended to described operations (e.g., computing operations) that are performed without any human-perceivable interruption between operations. For example, as used herein, data relating to the systems described herein may be collected, transmitted, and/or used in control computations in “substantially real time” such that data readings, data transfers, and/or data processing steps occur once every second, once every 0.1 second, once every 0.01 second, or even more frequent, during operations of the systems (e.g., while the systems are operating). In addition, as used herein, the terms “automatic” and “automated” are intended to describe operations that are performed or caused to be performed, for example, by a processing system (i.e., solely by the processing system, without human intervention). In addition, as used herein, the term “approximately equal to” may be used to mean values that are relatively close to each other (e.g., within 5%, within 2%, within 1%, within 0.5 %, or even closer, of each other).

The embodiments described herein provide perforating guns having one or more perforating charges and an initiator assembly. The initiator assembly includes one or more detonators configured to cause detonation of the one or more perforating charges. In addition, the initiator assembly includes one or more mechanical components configured to be actuated to transition the initiator assembly from a first mechanical configuration to a second mechanical configuration, wherein a detonation circuit of the initiator assembly is open when the initiator assembly is in the first mechanical configuration and the detonation circuit of the initiator assembly is closed when the initiator assembly is in the second mechanical configuration. As used herein, when referring to the various initiator assemblies described herein, the term “open” is generally intended to refer to a circuit configuration where lead wires from a switch are not electrically connected to the one or more detonators (e.g., thereby preventing explosive transfer from the one or more detonators to the one or more perforating charges), and the term “closed” is generally intended to refer to a circuit configuration where lead wires from a switch are electrically connected to the one or more detonators (e.g., thereby enabling explosive transfer from the one or more detonators to the one or more perforating charges).

In general, in order to initiate perforating charges, the detonation of the detonator will typically be used to propagate explosive detonation to a detonating cord or a booster on a detonating cord. The detonation of the detonating cord will propagate along its length and then activate the perforating shape charges. It will be appreciated that many of the drawings presented herein illustrate movement of the detonator, but do not illustrate the specific location(s) of a booster or a detonating cord or ballistic interrupt shutter. However, one skilled in the art should realize that appropriate placement of a booster or a detonating cord may be assumed when not explicitly shown.

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 a target zone 13 of 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.

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.

Certain embodiments 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 perforating charges 20 loaded into the perforating gun 15 (or into each gun of the gun string); 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 the perforating charges 20 within a target formation interval 13, wherein the conveyance mechanism 17 may be a wireline, tubing, or other conventional perforating deployment structure; among other components.

Referring to FIGS. 2 and 3, the material from a collapsed liner of the perforating charge 20 may form a perforating jet 28 that shoots through the front of the perforating charge 20 and penetrates the casing 12 and underlying formation 16 to form a perforation tunnel 40. Around the surface region adjacent to the perforation 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 perforation tunnel 40 and “tip” residue 30B deposited at the tip of the perforation tunnel 40.

FIGS. 4 and 5 depict a side view and a cross-sectional view of an illustrative perforating gun 15, according to one or more embodiments. The perforating gun 15 may have a body or carrier 42 having a first or “upper” end 44 and a second or “lower” end 46. The use of the terms “upper” and “lower” do not limit the orientation of the perforating gun 15, which may be placed at any angle with respect to a vertical plane within a wellbore 11. As illustrated in FIG. 5, the carrier 42 may have an inner bore 48 formed therethrough for containing a loading tube 50. The carrier 42 and the loading tube 50 may each be tubular members, and the loading tube 50 may be disposed longitudinally within the carrier 42. The loading tube 50 can have a first or “upper” end 52 and a second or “lower” end 54. In certain embodiments, an upper connector assembly 56 may be disposed on the loading tube 50, for example, at or near the first end 52, and a lower connector assembly 58 may be disposed on the loading tube 50, for example, at or near the second end 54. The upper connector assembly 56 and lower connector assembly 58 may include one or more projections or other features, such as tabs, rods, or cavities that may engage corresponding holes, recesses, or protrusions disposed in the carrier 42. In addition, the perforating gun 15 may contain an initiator assembly 60 configured to cause detonation of the perforating charges 20, as described in greater detail herein. In particular, the initiator assembly 60 may include a ballistic interrupt shutter 62 configured to prevent detonation until a command is sent to release the ballistic interrupt shutter 62, thereby closing the ballistic circuit between a detonating cord 64 and a detonator 66 of the perforating gun 15, as described in greater detail herein. As such, a perforating gun 15 fully loaded with perforating charges 20 may be safely handled and transported.

As illustrated, the loading tube 50 may also include one or more charge jacket holders 68 (six are at least partially shown in FIG. 1). The charge jacket holders 68 may contain perforating charges 20 that can be outwardly directed in a radial and/or tangential direction, for example, to perforate a casing 12 and/or form corresponding perforation tunnels 40 into the surrounding formation 16. The charge jacket holders 68 can be arranged in a phasing pattern (a helical or spiral phasing pattern, missing arc helical phasing pattern, a planar phasing pattern, and so forth), depending on the perforating application. As illustrated in FIG. 4, in certain embodiments, the loading tube 50 may include one or more detonating cord slots 70. The detonating cord slots 70 may be adapted to receive a detonating cord 64 for connecting to primer ends of the perforating charges 20 disposed in the charge jacket holders 68. In certain embodiments, the detonating cord slots 70 may be arranged in a manner similar to that of the charge jacket holders 68. For example, the detonating cord slots 70 may be arranged in a phasing pattern, such as a helical or spiral phasing pattern, a missing arc helical phasing pattern, or a planar phasing pattern. As also illustrated in FIG. 4, in certain embodiments, the loading tube 50 may also include one or more electrical wire holder holes 72 or other fastening features. The other fastening features may include fasteners or adhesives formed out of, placed on, or threaded through, the loading tube 50. The electrical wire holder holes or features 72 may be arranged in a manner similar to that of the charge jacket holders 68 and the detonating cord slots 70. For example, the electrical wire holder holes or features 72 may be arranged in a phasing pattern, such as a helical or spiral phasing pattern, a missing arc helical phasing pattern, or a planar phasing pattern. The electrical wire holder holes or features 72 may retain wire holders and give wires a dedicated path through the loading tube 50. Such an arrangement may protect wires from being pinched by the perforating charges 20 and may prevent shock damage to wires by providing strain relief.

The component parts of the perforating gun 15 may be formed from any material. For example, one or more component parts of the perforating gun 15 may be formed from metals, such as carbon steel, stainless steel, nickel, nickel alloys, iron, aluminum, tungsten, ceramics, plastic, composite materials, glass, and so forth. One or more component parts of the perforating gun 15 may also be formed from one or more thermoplastic materials, such as polymers, elastomers, rubbers, and so forth.

As described in greater detail herein, the perforating gun 15 may include an initiator assembly 60 having a ballistic interrupt shutter 62 configured to prevent detonation until a command is sent to release the ballistic interrupt shutter 62, thereby closing the ballistic circuit between a detonating cord 64 and a detonator 66 of the perforating gun 15. As such, a perforating gun 15 fully loaded with perforating charges 20 may be safely handled and transported. In certain embodiments, the initiator assembly 60 may include circuitry that releases the ballistic interrupt shutter 62 and fires the detonator 66 somewhat independently.

For example, FIGS. 6A and 6B illustrate an example initiator assembly 60 with the ballistic interrupt shutter 62 being transitioned from a deactivated position (i.e., FIG. 6A) to an activated/released position (FIG. 6B), as illustrated by arrow 74. In the embodiment illustrated in FIGS. 6A and 6B, the ballistic interrupt shutter 62 is spring-loaded by a shutter spring 76, which biases the ballistic interrupt shutter 62 into the activated/released position (FIG. 6B) when a firing current is received by the initiator assembly 60 and, for example, a shutter release mechanism 78 releases the ballistic interrupt shutter 62. After the ballistic interrupt shutter 62 is in the activated/released position (FIG. 6B), the detonator 66 and an explosive booster 80 may make contact to cause detonation of the perforating charges 20 described herein. It will be appreciated that, in certain embodiments, the detonator 66 and the explosive booster 80 may not make physical contact, but rather ballistic contact. The detonator 66 and the explosive booster 80 are sufficiently close and unimpeded to allow the explosive event to propagate from one to the other.

FIGS. 7A through 7C are various views of an example shutter release mechanism 78 for use in the initiator assembly 60 of FIGS. 6A and 6B. In particular, FIGS. 7A and 7B are perspective views of the shutter release mechanism 78 in a deactivated position (e.g., consistent with FIG. 6A) and an activated/released positions (e.g., consistent with FIG. 6B), respectively, and FIG. 7C is a section view of the shutter release mechanism 78 in the deactivated position (e.g., consistent with FIG. 6A). As illustrated, in certain embodiments, the (e.g., consistent with FIG. 6A) may include a set of opposing shutter release arms 82, both of which may be configured to pivot about a respective arm pivot point 84 and to be biased toward the activated/released position (FIG. 7B) by an arm spring 86 disposed between the shutter release arms 82 until respective shutter release arm tabs 88 of the shutter release arms 82 move far enough apart to enable the shutter spring 76 to bias the ballistic interrupt shutter 62 into the activated/released position (FIG. 7B). As illustrated in FIG. 7C, and described in greater detail herein, the shutter release mechanism 78 may include a fuse resistor 90 as part of the circuitry that enables the functionality of the shutter release mechanism 78.

In the embodiments illustrated in FIGS. 6A through 7C, the release of the ballistic interrupt shutter 62 and the firing of the detonator 66 occur separately. It should be noted that these embodiments are being presented as a contrast to the other embodiments described herein wherein the device must move from a first mechanical position to a second mechanical position in order to initiate a detonator and propagate the explosive event from the detonator to the booster or detonating cord. In particular, the other embodiments described herein include initiator assemblies 60 with ballistic interrupt shutters 62 that close the circuitry to their detonators 66, thereby preventing the detonators 66 from going off before the ballistic interrupt shutters 62 are released. In particular, ballistic transfer from the detonator 66 to the perforating charges 20 is possible only when the firing current is sent insofar as the detonator circuit is completed only upon release of the ballistic interrupt shutter 62. In other words, the ballistic interrupt shutter 62 itself closes the electric circuit to the detonator 66. As such, the embodiments described herein simplify the circuitry of the initiator assembly 60 and prevent the detonator 66 from ever even possibly going off before the ballistic interrupt shutter 62 is released.

FIGS. 8A and 8B are schematic diagrams of an example initiator assembly 60 where the detonator circuit 96 is not completed until the ballistic interrupt shutter 62 has been released. As illustrated in FIG. 8A, before a firing current is received by the initiator assembly 60, the ballistic interrupt shutter 62 is in the deactivated position and the detonator circuit 96 between the detonator 66 and an addressable switching firing system (ASFS) 94 is open. However, as illustrated in FIG. 8B, after the firing current is received by the initiator assembly 60, the ballistic interrupt shutter 62 may be released into the activated/released position wherein the ballistic interrupt shutter 62 comes into electrical contact with the detonator circuit 96 (e.g., electrical contacts) to fully complete the circuit between the detonator 66 and the ASFS 94, thereby initiating firing of the detonator 66.

In general, when the ASFS 94 has activated the circuitry for “FIRE,” current will flow through the shutter support circuit 92 causing an event that fails the circuit and allows the ballistic interrupt shutter 62 to drop from position 1 into position 2. This “failure” of the shutter support circuit 92 stops current flow through it, and once the ballistic interrupt shutter 62 is in position 2, current will flow through it and into the detonator 66.

As discussed above, when referring to the various initiator assemblies 60 described herein, the term “open” is generally intended to refer to a circuit configuration where lead wires from a switch (e.g., such as an ASFS 94) are not electrically connected to a detonator 66 (e.g., thereby preventing explosive transfer from the detonator 66 to perforating charges 20), and the term “closed” is generally intended to refer to a circuit configuration where lead wires from a switch (e.g., such as an ASFS 94) are electrically connected to a detonator 66 (e.g., thereby enabling explosive transfer from the detonator 66 to perforating charges 20).

FIG. 9 is a schematic diagram of an alternative initiator assembly 60. In the illustrated embodiment, a particular type of electromechanical device 78 may be used as a shutter release mechanism that fails with current to release the ballistic interrupt shutter 62, as illustrated by arrow 98. In addition, in certain embodiments, the ballistic interrupt shutter 62 may have an insulation layer 100 between conductive layers 102 of the ballistic interrupt shutter 62. In addition, in certain embodiments, a detonator shunt 104 may be broken when the ballistic interrupt shutter 62 drops. In certain embodiments, the detonator shunt 104 may be a spring-loaded contact from below that is displaced by the ballistic interrupt shutter 62 dropping from above.

FIG. 10 is a simplified schematic diagram of another initiator assembly 60 where physical contact between a conductive ballistic interrupt shutter 62 and electrical contacts 96 may be completed. As illustrated, in certain embodiments, the initiator assembly 60 may include one or more fuse resistors 90 in parallel with the ASFS 94 and the detonator 66. FIG. 11 is a simplified schematic diagram of another initiator assembly 60 that includes a delay circuit 106. In such an embodiment, the delay circuit 106 may be used to complete the circuit between the ASFS 94 and the detonator 66 after a given period of time (e.g., a predefined delay).

FIGS. 12A through 12C illustrate various view of an example initiator assembly 60. In particular, FIG. 12A is a perspective view of the initiator assembly 60, FIG. 12B is another perspective view of the initiator assembly 60 with an upper body portion 108 of the initiator assembly 60 removed from a lower body portion 110 of the initiator assembly 60 for illustration purposes, and FIG. 12C is cutaway perspective view of the initiator assembly 60 to further facilitate illustration of internal components of the initiator assembly 60. As illustrated, the initiator assembly 60 may include a pair of fuse resistors 90, which may be caused to break (or melt through application of excessive current, in certain embodiments), thereby releasing a ballistic interrupt shutter 62 that is biased by a shutter spring 76 to move away from a detonating cord 64 and a detonator 66 of the initiator assembly 60, as illustrated by arrow 112, to enable completion of the detonation circuit, as described in greater detail herein.

As described in greater detail herein, different types of initiator assemblies 60 may be used. In general, two different types of mechanical schemes may be employed:

• • (1) trigger (e.g., “hot knife”) mechanisms, which include fewer moving parts, such as fuse resistors 90 that enable more passive release of ballistic interrupt shutters 62; and
  • (2) shutter release mechanisms, which include more moving parts, such as shutter springs 76 to actively move ballistic interrupt shutters 62. In general, fewer moving parts are preferred.

An assumption behind using fuse resistors 90 is that they are relatively fragile elements, and may be prone to break. Certain embodiments described herein include a pair of fuse resistors 90 that implement a two-step shutter release sequence that compensates for mechanical damage to one of the fuse resistors 90 during transportation (e.g., if one breaks, the second will prevent release of the ballistic interrupt shutter 62. In certain alternative embodiments, only one fuse resistor 90 may be used. In other embodiments, Ni—Cr (nichrome) alloy wire may be used instead of fuse resistors 90. Using Ni—Cr alloy wire is generally more robust than fuse resistors 90. In addition, Ni—Cr alloy wire is a relatively simpler mechanical scheme than using multiple fuse resistors 90. It should be noted that each of the embodiments described herein that utilize fuse resistors 90 may instead use Ni—Cr alloy wire.

As described in greater detail herein, the shutter release mechanisms described herein may utilize either rotational or linear motion. In many of the embodiments described herein, heat from either an external source or from current flow may be used to activate the rotational or linear motion. For example, in the embodiments with current flow, a current may be caused to flow through the devices when in a first position, and this flow of current may be stopped after a transition to a second position. Some of the embodiments illustrated in the drawings do not show all of the required elements to enable such implementation (e.g., to apply current or other source of heat) but rather focus on the specific mechanical methods of moving the ballistic interrupt shutter 62 or the detonator 66 between first and second positions. However, it will be appreciated that these embodiments will also include other elements to enable such implementations (e.g., to apply currents or other sources of heat).

FIG. 13 illustrates an example initiator assembly 60 having a spring-loaded ballistic interrupt shutter 62 in a first (e.g., deactivated) position 114 and a second (e.g., activated) position 116. In the embodiment illustrated in FIG. 13, a torsion spring spring-loads the ballistic interrupt shutter 62 when the ballistic interrupt shutter 62 is still and the torsion spring is compressed (e.g., the deactivated position 114) but then the torsion spring expands to move the ballistic interrupt shutter 62 into the activated position 116. As illustrated, in certain embodiments, a hot knife trigger 118 (e.g., a fuse resistor 90, a Ni—Cr alloy wire, etc.) may be used to release a shutter arm 120 attached to the ballistic interrupt shutter 62. However, in other embodiments, as described in greater detail herein, a shape memory alloy (e.g., nitinol spring activated by current or heat) or other release mechanism may be used to release the shutter arm 120 and the ballistic interrupt shutter 62. When the ballistic interrupt shutter 62 moves from the deactivated position 114 to the activated position 116, as illustrated by arrow 122, a jumper 124 attached to the ballistic interrupt shutter 62 may come into contact with electrical contacts 96 to complete a detonation circuit, as described in greater detail herein.

As described in greater detail herein, a shape memory alloy (SMA), such as a Ni—Ti alloy, may be used to actuate movement of a ballistic interrupt shutter 62. As illustrated in FIG. 14, the shape of a high temperature austenite phase is “remembered”. A transition temperature may be experienced via external heating or by passing electrical current through the SMA. Such a transition temperature may be tuned, for example, by modifying the Ni/Ti ratio or using additives, up to approximately 167° F.

As described in greater detail herein, an SMA spring may be used directly as a shutter drive or as an arm release trigger mechanism. In general, using an SMA spring as an arm release trigger mechanism is relatively smaller and enable control of relatively larger loads. FIG. 15 illustrates an example initiator assembly 60 that uses an SMA spring 126 as an arm release mechanism that releases a shutter arm 120 attached to a ballistic interrupt shutter 62 such that the ballistic interrupt shutter 62 may transition from a first (e.g., de activated) position 114 and a second (e.g., activated) position 116, similar to the embodiment illustrated in FIG. 13. Also similar to the embodiment illustrated in FIG. 13, when the ballistic interrupt shutter 62 moves from the deactivated position 114 to the activated position 116, as illustrated by arrow 122, a jumper 124 attached to the ballistic interrupt shutter 62 may come into contact with electrical contacts 96 to complete a detonation circuit, as described in greater detail herein. As illustrated in FIG. 15, once heat is applied to the SMA spring 126, a curved (or bent) axial end 128 of the SMA spring 126 straightens out to enable release of the shutter arm 120, thereby enabling a torsional spring to move the ballistic interrupt shutter 62 from the deactivated position 114 to the activated position 116.

FIGS. 16A and 16B illustrate another example initiator assembly 60 having a reversible shutter drive (e.g., via linear compression) that is powered by an SMA spring 126. As illustrated, when heat is applied to the linear SMA spring 126, the linear SMA spring 126 overcomes an opposing linear spring force applied by another (e.g., metal) linear spring 130 that biases the ballistic interrupt shutter 62 in the opposite linear direction (i.e., toward an explosive booster 80 and a detonator 66 of the initiator assembly 60) such that the SMA spring 126 gradually moves the ballistic interrupt shutter 62 away from the explosive booster 80 and the detonator 66, as illustrated by arrows 132, similar to other embodiments described herein. As will be appreciated, once the heat is no longer applied to the SMA spring 126, the SMA spring 126 may gradually return to its shape in FIG. 16A such that the positioning of the ballistic interrupt shutter 62 is reversible, for example, when the linear spring force applied from the other spring 130 overcomes the linear spring force applied by the SMA spring 126.

FIGS. 17A and 17B illustrate another example initiator assembly 60 having a torsional SMA spring drive. In particular, instead of using a linear SMA spring 126 as illustrated in FIGS. 16A and 16B, the embodiment illustrated in FIGS. 17A and 17B uses a torsional SMA spring 126. As illustrated, when heat is applied to the torsional SMA spring 126, the torsional SMA spring 126 forces the ballistic interrupt shutter 62 to move in a first radial direction about a shutter shaft 135 (e.g., shutter pivot point), as illustrated by arrow 134, to overcome an opposing torsional spring force applied by another (e.g., metal) torsional spring 136 that biases the ballistic interrupt shutter 62 in the opposite radial direction about the shutter shaft 135 (e.g., shutter pivot point), as illustrated by arrow 138, to move the ballistic interrupt shutter 62 from the deactivated position 114 to the activated position 116. As will be appreciated, once the heat is no longer applied to the torsional SMA spring 126, the torsional SMA spring 126 may gradually return to its shape in FIG. 17A such that the positioning of the ballistic interrupt shutter 62 is reversible, for example, when the torsional spring force applied from the other torsional spring 136 overcomes the torsional spring force applied by the torsional SMA spring 126.

FIGS. 18A through 18F illustrate various views of another example initiator assembly 60 having a linear SMA or solenoid trigger mechanism. For example, the initiator assembly 60 may include a linear trigger assembly 140 having a linear SMA spring 126 that disposed directly linearly opposite another linear spring 142. In addition, both the linear SMA spring 126 and the other linear spring 142 are coupled to a shutter trigger body 144 having a slot 146 (e.g., open space) disposed therethrough. As illustrated in FIG. 18C, when heat is applied to the linear SMA spring 126, the linear forces applied against the shutter trigger body 144 by the linear SMA spring 126 and the other linear spring 142 are affected such that the shutter trigger body 144 slides from a first position 148 within the linear trigger assembly 140 (e.g., where the slot 146 of the shutter trigger body 144 does not align with corresponding slots 152 through the linear trigger assembly 140) to a second position 150 within the linear trigger assembly 140 (e.g., where the slot 146 of the shutter trigger body 144 aligns with corresponding slots 152 through the linear trigger assembly 140). In the second position 150, the aligned slots 146, 152 enable release of the ballistic interrupt shutter 62, which may be radially biased by a torsional spring 154 that functions to move the ballistic interrupt shutter 62 from a first (e.g., deactivated) position 114 and a second (e.g., activated) position 116, similar to other embodiments described herein.

FIGS. 19A and 19B illustrate another example initiator assembly 60 having a relatively compact SMA or solenoid trigger mechanism. As illustrated, this embodiment includes a single linear SMA spring 126 configured to apply a linear force, as illustrated by arrow 156, to an axial end 158 of a shutter trigger cam 160 that pivots about a pivot point 162. Rotation of the shutter trigger cam 160 caused by the linear force 156, as illustrated by arrow 164, causes a protruding extension 166 of the shutter trigger cam 160 to move away from an abutting lip 168 on the ballistic interrupt shutter 62, thereby enabling a torsional spring 154 to move the ballistic interrupt shutter 62 from a first (e.g., deactivated) position 114 to a second (e.g., activated) position 116 via rotation of the ballistic interrupt shutter 62 about a shutter shaft 135 (e.g., shutter pivot point), as illustrated by arrow 170, similar to other embodiments described herein.

Although the embodiments described above generally include SMA springs 126 that are either linear SMA springs or torsional SMA springs, in other embodiments, an initiator assembly 60 may include an SMA spring 126 that, when activated (e.g., when heat is applied), extends in a manner that the SMA spring 126 returns from a generally non-linear deformed shape to a generally linear pre-deformed (e.g., remembered) shape. FIGS. 20A and 20B illustrate another example initiator assembly 60 having an SMA trigger mechanism that moves from a first (e.g., deactivated) position 114 where an SMA spring 126 is in a relatively non-linear shape to a second (e.g., activated) position 116 where the SMA spring 126 is in a relatively linear shape, as illustrated by arrow 172, when heat is applied to the SMA spring 126. It will be appreciated that, in other embodiments, an SMA spring 126 of an initiator assembly 60 may instead move from a first (e.g., deactivated) position 114 where the SMA spring 126 is in a relatively linear shape to a second (e.g., activated) position 116 where the SMA spring 126 is in a relatively non-linear shape when heat is applied to the SMA spring 126. In this embodiment, no circuitry is closed so current can flow to the detonator 66 at any time. This is generally an external heat activated design, although some additional mechanisms or circuitry could be added to make this a current flow heat design.

FIGS. 21A and 21B illustrate another example initiator assembly 60 having a resistor-triggered spring-loaded ballistic interrupt shutter 62. As illustrated, this embodiment includes a pair of fuse resistors 90 coupled to respective arms 174 extending from the ballistic interrupt shutter 62 opposite a main body portion 176 of the ballistic interrupt shutter 62 relative to a shutter shaft 135 about which the ballistic interrupt shutter 62 rotates, as described with reference to multiple embodiments herein. When excessive current is applied to the fuse resistors 90, the fuse resistors 90 may melt, thereby releasing the arms 174 of the ballistic interrupt shutter 62, at which point a torsional spring 154 may move the ballistic interrupt shutter 62 from a first (e.g., deactivated) position 114 to a second (e.g., activated) position 116 via rotation of the ballistic interrupt shutter 62 about the shutter shaft 135 (e.g., shutter pivot point), as illustrated by arrow 178, similar to other embodiments described herein. It will be appreciated that any number of fuse resistors 90 may be used in the embodiment illustrated in FIGS. 21A and 21B.

FIGS. 22A and 22B illustrate another example initiator assembly 60 having a resistor-triggered spring-loaded ballistic interrupt shutter 62. As illustrated, this embodiment also includes a pair of fuse resistors 90 coupled to respective arms 180 extending from the ballistic interrupt shutter 62. However, the arms 180 of the embodiment illustrated in FIGS. 22A and 22B are positioned slightly differently than the embodiment illustrated in FIGS. 21A and 21B. Similar to the embodiment illustrated in FIGS. 21A and 21B, when excessive current is applied to the fuse resistors 90, the fuse resistors 90 may melt, thereby releasing the arms 180 of the ballistic interrupt shutter 62. However, in the embodiment illustrated in FIGS. 22A and 22Ba linear spring 182 may move the ballistic interrupt shutter 62 from a first (e.g., deactivated) position 114 to a second (e.g., activated) position 116 via translation of the ballistic interrupt shutter 62, as illustrated by arrow 184. Again, it will be appreciated that any number of fuse resistors 90 may be used in the embodiment illustrated in FIGS. 22A and 22B.

FIGS. 23A through 23F illustrate another example initiator assembly 60 having a rotating detonator 66, instead of a rotating ballistic interrupt shutter 62 as in a few other embodiments described herein. As best illustrated in FIGS. 23A, 23B, and 23E, similar to the embodiments illustrated in FIGS. 19A and 19B, this embodiment includes a single linear SMA spring 126 configured to apply a linear force, as illustrated by arrow 186, to an axial end 188 of a detonator trigger cam 190 that pivots about a pivot point 192. Rotation of the detonator trigger cam 190 caused by the linear force 186, as illustrated by arrow 194 in FIG. 23A, causes a protruding extension 196 of the detonator trigger cam 190 to move away from an abutting lip 198 on the detonator 66, thereby enabling one or more torsional springs 154 (e.g., two torsional springs 154, in the illustrated embodiment) to move the detonator 66 from a first (e.g., deactivated) position 200 to a second (e.g., activated) position 202 via rotation of the detonator 66 about a detonator shaft 204 (e.g., detonator pivot point), as illustrated by arrow 206 in FIG. 23A, similar to other embodiments described herein. It is noted that FIGS. 23A and 23C show the rotating detonator 66 in both positions 200, 202 in order to illustrate the juxtaposition between the two positions.

In addition, in certain embodiments, the initiator assembly 60 may include one or more additional torsional springs 208 (e.g., two torsional springs 208, in the illustrated embodiment) configured to bias the detonator trigger cam 190 in an opposite radial direction as opposed to the radial direction that the linear force applied by the linear SMA spring 126 against the detonator trigger cam 190 causes. In addition, as illustrated in FIGS. 23A, 23C, 23D, and 23F, in certain embodiments, two additional torsional spring portions 208 may be connected together via a torsional spring connector 210, which abuts the detonator trigger cam 190.

FIGS. 24A through 24F illustrate another example initiator assembly 60 having a rotating detonator 66. As illustrated, similar to the embodiments illustrated in FIGS. 21A and 21B, this embodiment includes a pair of fuse resistors 90 coupled to respective arms 214 extending from the detonator 66. When excessive current is applied to the fuse resistors 90, the fuse resistors 90 may melt, thereby releasing the arms 214 of the detonator 66, at which point one or more torsional springs 154 (e.g., two torsional springs 154, in the illustrated embodiment) move the detonator 66 from a first (e.g., deactivated) position 200 to a second (e.g., activated) position 202 via rotation of the detonator 66 about a detonator shaft 204 (e.g., detonator pivot point), as illustrated by arrow 206 in FIGS. 24A and 24E, similar to other embodiments described herein. It will be appreciated that any number of fuse resistors 90 may be used in the embodiment illustrated in FIGS. 24A through 24F. In addition, in certain embodiments, the detonator 66 may include an opening 212 extending therethrough to allow the detonator 66 to have access to the detonating cord booster 80 to which it must transfer detonation shock. The wires can access the detonator 66 from an opposite end opening or vice versa.

FIGS. 25A and 25B illustrate another embodiment of an initiator assembly 60 that includes movement of a detonator 66 (e.g., disposed within a detonator holder) from a ballistic interrupt (e.g., deactivated) position 200 to a non-interrupt (e.g., activated) position 202. For example, as illustrated, in certain embodiments, an SMA spring 126 may cause the movement of the detonator 66 from the first position 200 to the second position 202. As also illustrated, a ballistic interrupt barrier 216 prevents contact of the detonator 66 with the detonating cord 64 in the first position 200. It will be appreciated that, in other embodiments, the detonating cord 64 may instead be configured to move from an interrupt position to a non-interrupt position, as opposed to the detonator 66 being the component that moves, such as the embodiment illustrated in FIGS. 25A and 25B.

In addition, in certain embodiments, instead of using an SMA spring 126, a detonator 66 may instead be disposed within a detonator holder with one or more arms, and the SMA spring 126 may be replaced with a regular spring while the arm(s) are held in position by one or more fuse resistors 90, as described herein. Once the fuse resistors 90 are burned, the arm(s) would no longer hold the spring in position, allowing it to move from the first position 200 to the second position 202.

As such, in certain embodiments, the embodiments described herein provide a perforating gun 15 that includes one or more perforating charges 20, and an initiator assembly 60. In addition, in certain embodiments, the initiator assembly 60 may include one or more detonators 66 configured to cause detonation of the one or more perforating charges 20. In addition, in certain embodiments, the initiator assembly 60 may include one or more mechanical components configured to be actuated to transition the initiator assembly 60 from a first mechanical configuration (e.g., a deactivated configuration) to a second mechanical configuration (e.g., an activated configuration), wherein a detonation circuit of the initiator assembly 60 is open when the initiator assembly 60 is in the first mechanical configuration to prevent the one or more detonators 66 from detonating the one or more perforating charges 20 (e.g., either directly or via a detonating cord 64 or a detonating cord booster 80) and the detonation circuit of the initiator assembly 60 is closed when the initiator assembly 60 is in the second mechanical configuration to enable the one or more detonators 66 to detonate the one or more perforating charges 20 (e.g., either directly or via a detonating cord 64 or a detonating cord booster 80).

In certain embodiments, the one or more mechanical components of the initiator assembly 60 may include a ballistic interrupt shutter 62 configured to be actuated to transition from a first position 114 in the first mechanical configuration to a second position 116 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60. In addition, in certain embodiments, the ballistic interrupt shutter 62 is configured to translate (e.g., via linear actuation) from the first position 114 in the first mechanical configuration to the second position 116 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60. However, in other embodiments, the ballistic interrupt shutter 62 is configured to rotate about a shutter shaft 135 of the ballistic interrupt shutter 62 (e.g., via rotational actuation) from the first position 114 in the first mechanical configuration to the second position 116 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60.

In certain embodiments, the one or more mechanical components of the initiator assembly 60 may include one or more fuse resistors 90 configured to receive excess current to melt to release the ballistic interrupt shutter 62, thereby enabling the transition of the ballistic interrupt shutter 62 from the first position 114 in the first mechanical configuration to the second position 116 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60. However, in other embodiments, the one or more mechanical components of the initiator assembly 60 may include an SMA spring 126 configured to be actuated via application of heat to enable the transition of the ballistic interrupt shutter 62 from the first position 114 in the first mechanical configuration to the second position 116 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60.

In embodiments utilizing an SMA spring 126, in certain embodiments, the SMA spring 126 may include a linear SMA spring 126 configured to be actuated via the application of the heat to enable the transition of the ballistic interrupt shutter 62 from the first position 114 in the first mechanical configuration to the second position 116 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60. In other embodiments, the SMA spring 126 may include a torsional SMA spring 126 configured to be actuated via the application of the heat to enable the transition of the ballistic interrupt shutter 62 from the first position 114 in the first mechanical configuration to the second position 116 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60.

In addition, in certain embodiments, the one or more mechanical components of the initiator assembly 60 may include an SMA spring configured to be actuated via application of heat to transition between a non-linear shape and a linear shape to close the detonation circuit of the initiator assembly 60. In addition, in certain embodiments, the one or more mechanical components of the initiator assembly 60 may include a detonator holder 66 configured to be actuated to transition from a first position 200 in the first mechanical configuration to a second position 202 in the second mechanical configuration to close the detonation circuit of the initiator assembly 60.

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.

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).