CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63/488,275 filed March 3, 2023 and U.S. Provisional Patent Application No. 63/398,887 filed August 18, 2022, the entire contents of each of which are incorporated by reference herein.

BACKGROUND OF THE DISCLOSURE

[0002] Hydraulic Fracturing (“fracking”) is a commonly-used method for extracting oil and gas from geological formations (i.e., “hydrocarbon bearing formations”) such as shale and tight-rock formations. Fracking is a time- and labor-intensive operation involving drilling a wellbore, installing casings in the wellbore, perforating the wellbore, pumping high-pressure fracking fluids into the wellbore, and collecting the liberated hydrocarbons.

[0003] Typical devices, systems, and methods for perforating the wellbore include pumping down into the wellbore a perforating gun attached to a wireline connected at the surface to a control unit and perforating the wellbore in stages. This may be achieved by a perforating tool string containing several perforating guns. Each perforating gun can be addressed separately by a control device; therefore, the electrical connection in each gun may be configured to bypass the electrical signal to the next perforating gun via an electrical feedthrough.

[0004] In general, the perforating guns can be sorted into two types: disposable, factory assembled, and easily-armed perforating guns; and perforating guns that are assembled by the customer, not disposable, and that require manual wiring of the detonator. The non-disposable parts are the connectors to the perforating guns, which can be retrieved and reused.

[0005] The manual wiring of the detonator by the customer may unreliable due to human error and the lack of standardized quality control measures.

SUMMARY

[0006] According to an aspect of the present disclosure, a tandem sub is provided that includes a main body, an insulative housing assembly, and a detonator. The main body has a first end portion configured to couple to a first wellbore tool, and a second end portion configured to couple to a second wellbore tool. The main body defines a bore therethrough and the insulative housing assembly is configured for receipt in the bore. The insulative housing assembly includes an insulative head defining an inner chamber, an insulative body extending from the insulative head and defining a channel, and a spring-loaded ground contact coupled to the insulative head. The detonator includes a detonator head configured for receipt in the inner chamber of the insulative head, and a detonator hull extending from the detonator head and configured for receipt within the channel of the insulative body. The detonator head has an electrical ground contact configured to be in electrical communication with the spring- loaded ground contact when the detonator is received within the insulative housing assembly.

[0007] According to another aspect of the present disclosure, an insulative housing assembly for a detonator is provided and includes an insulative head, an insulative body extending from the insulative head, and a spring-loaded ground contact received in an inner chamber of the insulative head. The inner chamber of the insulative head is configured for receipt of a first portion of a detonator. The insulative body defines a channel configured for receipt of a second portion of the detonator. The spring-loaded ground contact includes a contact plate configured to translate within the inner chamber of the insulative head upon the first portion of the detonator being received in the inner chamber of the insulative head.

[0008] According to another aspect of the present disclosure, an explosive wellbore tool string is provided and includes a first perforating gun including a charge tube, a second perforating gun including a charge tube, a tandem sub, a bulkhead, and first and second contact kits. The tandem sub includes a main body having a first end portion configured to couple to the first perforating gun and a second end portion configured to couple to the second perforating gun. The main body defines a bore therethrough. The tandem sub includes an insulative housing assembly positioned in the bore of the main body, and a detonator positioned in the insulative housing assembly. The bulkhead is configured to be in electrical communication with the detonator. The first contact kit is configured to be coupled between the bulkhead and the charge tube of the first perforating gun and positioned within a first end portion of the bore of the main body. The second contact kit is configured to be coupled to the detonator and positioned within a second end portion of the bore of the main body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A more particular description will be rendered by reference to exemplary embodiments that are illustrated in the accompanying figures. Understanding that these drawings depict exemplary embodiments and do not limit the scope of this disclosure, the exemplary embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: [0010] FIG. 1 is a cross-sectional view of aspects of a perforating gun string or system including a tandem sub intercoupling first and second perforating guns, and first and second contact kits according to aspects of the present disclosure;

[0011] FIG. 2 is a magnified view of the tandem sub of FIG. 1;

[0012] FIG. 3 is a cross-sectional view of an insulative housing assembly of the tandem sub of FIG. 1;

[0013] FIG. 4 is a cross-sectional view illustrating the first and second contact kits assembled to the tandem sub of FIG. 1;

[0014] FIG. 5 is a magnified view of a first end portion of the tandem sub and first contact kit of FIG. 4;

[0015] FIG. 6 is a magnified view of a second end portion of the tandem sub and second contact kit of FIG. 4;

[0016] FIG. 7 is a perspective view illustrating aspects of the second contact kit of FIG. 4;

[0017] FIG. 8 is a cross-sectional view of an exemplary embodiment of a cutter assembly;

[0018] FIG. 9 is a cross-sectional view of an exemplary embodiment of a tandem sub used with perforating guns;

[0019] FIG. 10 is a cross-sectional view of an exemplary embodiment of a tandem sub used with a quick change assembly and a perforating gun;

[0020] FIG. 11 is a cross-sectional view of an exemplary embodiment of a tandem sub used with perforating guns; and

[0021] FIG. 12 is a cross-sectional view of an exemplary embodiment of a tandem sub used with a cross-over sub and a perforating gun.

[0022] Various features, aspects, and advantages of the exemplary embodiments will become more apparent from the following detailed description, along with the accompanying drawings in which like numerals represent like components throughout the figures and detailed description. The various described features are not necessarily drawn to scale in the drawings but are drawn to emphasize specific features relevant to some embodiments.

[0023] The headings used herein are for organizational purposes only and are not meant to limit the scope of the disclosure or the claims. To facilitate understanding, reference numerals have been used, where possible, to designate like elements common to the figures. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to various embodiments. Each example is provided by way of explanation and is not meant as a limitation and does not constitute a definition of all possible embodiments.

[0025] For purpose of this disclosure, “perforating gun” means a wellbore tool that contains one or more explosive components designed to be initiated inside a wellbore. For purpose of this disclosure, the term “perforating gun” may include a puncher gun, oriented perforating guns, junk shots, jet cutter, severing tools, or logging tools that include explosives, but is not limited to these specific tools.

[0026] For purpose of this disclosure, “tandem connector” or “tandem sub” means a connector that connects two wellbore tools of a wellbore tool string. The wellbore tool may be a cable head, a perforating gun, a logging tool, a weight bar, a setting tool, a cross-over sub, or a surge chamber, but is not limited to these tools. The connection may be made via threads, latch connector, or bolted connection, but is not limited to these. In some aspects, the “tandem sub” may be an assembly that includes a conductive main body for intercoupling adjacent perforating guns, a detonator, and an insulative housing assembly, as will be described.

[0027] For purposes of illustrating features of the embodiments, an exemplary embodiment will now be introduced and referenced throughout the disclosure. This example is illustrative and not limiting and is provided for illustrating the exemplary features of a tandem sub with a selective top fire detonator as described throughout this disclosure.

[0028] Turing now to FIGS. 1 and 2, a perforating gun string or system 1 is shown that generally includes a first perforating gun 20, a second perforating gun 30, and a tandem sub 10 coupled to and disposed between the first and second perforating guns 20, 30. Seals, such as, for example, annular or O-ring seals 16 may be provided between an outer surface of the tandem sub 10 and an inner surface of each of the perforating guns 20, 30 to form a fluid-tight and pressure-tight connection therebetween. Each perforating gun 20, 30 has a perforating gun housing 22, 32 and a charge tube 24, 34 extending within the perforating gun housing 22, 32. Each of the housings 22, 32 enclose a perforating shaped charge (not explicitly shown) and protects the perforating shaped charge from wellbore fluids, which ensures the correct function of the shaped charges. The charge tubes 24, 34 function as holders for the shaped charges of each perforating gun 20, 30. Each charge tube 24, 34 has a respective end plate 26, 36 connected to a respective first end of the charge tubes 24, 34. It is contemplated that an opposite, second end (not explicitly shown) of the charge tubes 24, 34, may also include a respective end plate. Further details regarding the first and second perforating guns 20, 30 will be described below.

[0029] The tandem sub 10 includes a main body 12, an insulative housing assembly 14, and a detonator 900. The main body 12 may be fabricated from a conductive material, such as, for example, a metal, and defines a longitudinally-extending bore 14 therethrough. The bore 14 may be centrally located within the main body 12 and includes a first end portion 14a, a second end portion 14b, and a central portion 14c. The outer surface of the main body 12 may define an annular recess 13 therein that is positioned at a central location of the main body 12. The insulative housing assembly 40 is positioned inside the central portion 14c of the bore 14. The central portion 14c of the bore 14 may be a counterbore that complimentarily receives the insulative housing assembly 40 therein.

[0030] With reference to FIGS. 2 and 3, the insulative housing assembly 40 includes an insulative body 41, an insulative head 43 integrally formed with or coupled to an end portion of the insulative body 41, and a spring-loaded ground contact assembly 48 at least partially received within an inner chamber 45 of the insulative head 43. The insulative body 41 may be a tube that defines a central channel 47 therethrough. The insulative body 41 has an annular flange 49 extending radially outward from an outer surface of an end portion thereof. The insulative head 43 and the insulative body 41 may be fabricated from any suitable plastic, such as, for example, a polymeric material, a thermoplastic material (polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), polystyrene (PS), nylon (aka polyamide (PA)), polyester (typically polyethylene terephthalate (PET)), polyalkelene glycol (PAG) with or without glass fiber, polyetheretherketone (PEEK), or silicone), high density polyethylene (HDPE), low density polyethylene (LPDE) or linear low density polyethylene (LLPDE).

[0031] The spring-loaded ground contact assembly 48 includes a contact plate 42, a spring 44, and a contact clip 46. The contact clip 46 is attached to the annular flange 49 of the insulative body 41 and has a first portion 46a positioned within the inner chamber 45 of the insulative head 43 and a second portion 46b positioned on the outside of the insulative housing assembly 40. The first portion 46a of the contact clip 46 contacts a first end 44a of the spring 44 and axially restrains the first end portion 44a of the spring 44 to the insulative body 41. The spring 44 has a second end portion 44b that supports the contact plate 42 and resiliently biases the contact plate 42 toward an extended position, as shown in FIG. 3. Upon the contact plate 42 receiving a force oriented in an axial direction “A” shown in FIG. 3, the contact plate 42 is moved (e.g., translated) inwardly into the inner chamber 45 of the insulative head 43 against the resilient bias of the spring 44. For example, the contact plate 42 may be in contact with a ground contact 908 (FIG. 2) of the detonator 900 upon assembling the detonator 900 with the insulative housing assembly 40. The contact plate 42 defines a central opening 56 therethrough configured to permit slidable receipt of a portion of the detonator 900 (e.g., a conductive hull 902 of the detonator 900). In other words, when assembled, at least a portion of the detonator 900 protrudes through the central opening 56 of the contact plate 42.

[0032] The detonator 900 includes a detonator head 904, from which the detonator hull 902 extends. The detonator head 904 has an electrical in-line contact 906 and an electrical ground contact 908. The explosive components are located inside the conductive hull 902 and may include a primary explosive load 914 (which may be inside a “non-mass-explosive” (NME) body 916) and a secondary explosive load 918. An initiation device 912 (e.g. a fuse head) is adjacent to the explosives and in electrical contact with electronics 910 of the detonator 900.

[0033] The system 1 may further include a bulkhead 50 configured to be positioned within the first end portion 14a of the bore 14 of the main body 12 and adjacent the detonator head 904. The bulkhead may be in electrical contact or electrical communication with the in-line contact 906 of the detonator 900. The bulkhead 50 may act as a sealing device towards the first perforating gun 20. The bulkhead 50 may have electrical contact pins 54a, 54b through which an electrical signal for operating the detonator 900 is sent. The bulkhead 50 may be secured in the first end portion 14a of the bore 14 of the main body 12 by a retainer nut 52. A rigid ring 53 (FIG. 4) may be provided between the bulkhead 50 and the insulative housing assembly 40 to provide structural stabilization for the bulkhead 50.

[0034] With reference to FIGS. 1 and 4-6, the system 1 may include first and second spring- loaded contact kits 60, 70 coupled to opposite end portions 12a, 12b of the main body 12. The contact kits 60, 70 may be received within the respective first and second end portions 14a, 14b of the bore 14 of the main body 12 and are each coupled to the respective end portion of the charge tubes 24, 34. The first contact kit 60 includes an insulative body 62, an electrical connector 64 extending through the insulative body 62, a cable contact 66 extending radially outward from an end of the electrical connector 64, and a spring 68. The insulative body 62 surrounds the electrical connector 64 and insulates the electrical connector 64 from the end plate 26 and the main body 12. The spring 68 is located between the end plate 26 and the insulative body 62 and resiliently biases the insulative body 62 into the first end portion 14a of the bore 14 of the main body 12. The electrical connector 64 is in contact with the contact pin 54b of the bulkhead 50 such that a signal to initiate the detonator 900 may be sent from the cable contact 66, through the electrical connector 64 and the bulkhead 50, into the detonator 900.

[0035] As best shown in FIGS. 4 and 5, a collar or guide 69 is provided for stabilizing the first contact kit 60 in the end portion 14a of the bore 14. The guide 69 abuts the retainer nut 52 that is threadedly engaged to a threaded inner surface of the first end 12a of the main body 12. The guide 69 may define a tapered or conical inner surface 71 configured to guide an axial insertion of the insulative body 62 into the end portion 14a of the bore 14. The guide 69 also ensures that electric contact is maintained between the contact pin 54b of the bulkhead 50 and the electrical connector 64 of the contact kit 60 even if the charge tube 24 is bent or deformed (e.g., during deployment). The guide 69 may also limit the space between the contact kit 60 and the tandem sub 10 such that contact kit 60 remains centered even if the charge tube 24 is in a bent state. In addition, a thickness of a receiving portion 67 of the insulative body 62 is reduced to account for any tilting between the contact kit 60 and the contact pin 54b.

[0036] With reference to FIGS. 1, 4, 6, and 7, the second contact kit 70 may be a combined ballistic and electric contact kit that extends between the charge tube 34 and the tandem sub 10. More specifically, the kit 70 has a first end portion received within a second end portion 14b of the bore 14 of the tandem sub 10, and a second end portion extending through the charge tube end plate 36. The second contact kit 70 includes an elongated insulative body 72, an electrically conductive booster holder or electrical connector 74 extending coextensively within the elongated insulative body 72, a cable contact 76 extending radially outward from the booster holder 74, and a spring 78 positioned about the elongated insulative body 72. The spring 78 is positioned between an end 79 of the elongated insulative body 72 and the charge tube end plate 36 such that the spring 78 maintains the kit 70 in engagement with the main body 12 of the tandem sub 10.

[0037] The booster holder or electrical connector 74 of the second contact kit 700 protrudes from the end 79 of the elongated insulative body 72 into the end portion 14b of the bore 14 of the main body 12. The kit 70 may further include a booster hull 80 that extends within the booster holder 74 and houses a ballistic transfer, such as a ballistic booster or explosive material 84. The booster hull 80 is configured to abut the conductive hull 902 of the detonator 900 such that the explosive material 84 of the second contact kit 70 and the secondary explosive load 918 of the detonator 900 are adjacent one another. A detonating cord 86 is positioned within the booster holder 74 and extends from the explosive material 84 of the second contact kit 70, through the booster holder 74 and into the charge tube 34 of the second perforating gun 30. The detonating cord 86 is configured to receive a ballistic impulse, via the detonator 900 and the booster kit 70, and initiate shaped charges (not explicitly shown) inside the second perforating gun 30. The ballistic booster holder 74 is also configured to receive an electric signal from a feedthrough electrical contact (e.g., the detonator hull 902) of the detonator 900. Alternatively, the electrical signal may be received by the booster hull 80 instead of directly by the booster holder 74 in an aspect of the disclosure where the booster hull 80 is fabricated from a conductive material. The electrical signal may be transmitted to another perforating gun (not explicitly shown) of the string 1 via the cable contact 76.

[0038] With reference to FIGS. 6 and 7, the cable contact 76 of the contact kit 70 extends radially outward (e.g., perpendicular) from an end of the electrical connector 74 of the contact kit 70. The cable contact 76 may include a pair of plate-like flexible arms 76a, 76b that define a circular recess 76c therebetween. As such, as the cable contact 76 slides into engagement with an end of the electrical connector 74, the flexible arms 76a, 76b flex apart from one another to accommodate the end of the electrical connector 74 in the recess 76c. The cable contact 76 may further include a plurality of struts 73 that surround the recess 76c. The struts 73 are configured for receipt within an annular groove 75 defined in an outer surface of the electrical connector 74 and prevent the cable contact 76 from sliding axially off of the end of the electrical connector 74.

[0039] When assembling the perforating gun string 1, the tandem sub 10 is attached to the second perforating gun 30 by inserting the second end portion 12b of the main body 12 of the tandem sub 10 within the outer housing 32 of the second perforating gun 30. The tandem sub 10 may be threadedly or frictionally coupled to the second perforating gun 30. In aspects, the insulative housing assembly 40 may be positioned within the bore 14 of the main body 12 of the tandem sub 10 before or after the second perforating gun 30 is secured to the tandem sub 10. In aspects, the insulative housing assembly 40 may be assembled to the tandem sub 10 during manufacturing. With the insulative housing assembly 40 positioned within the bore 14, the contact clip 46 of the insulative housing assembly 40 is in contact with the conductive main body 12 of the tandem sub 10.

[0040] With the main body 12 of the tandem sub 10 secured to the second perforating gun 30 and the insulative housing assembly 40 positioned within the bore 14 of the main body 12, the detonator 900 is axially inserted into the insulative housing 40, whereby the ground contact loaded ground contact assembly 48. In aspects, the detonator 900 may be preassembled within the insulative housing assembly 40 and the preassembled detonator 900 and insulative housing assembly 40 may be assembled into the tandem sub 10 as a unit. As the detonator 900 is further axially inserted into the insulative housing assembly 40, the contact plate 42 of the insulative housing assembly 40 translates through the inner chamber 45 of the insulative head 43 against the resilient bias of the spring 44 thereby ensuring a strong electrical contact between the ground contact 908 and the contact plate 42. By inserting the detonator 900 into the insulative housing assembly 40, the ground contact 908 is enabled and each of the detonator head 904, the electronics 910, and the fuse head 912 of the detonator 900 are insulated from the main body 12 by the insulative housing assembly 40. In addition, upon inserting the detonator 900 into the insulative housing assembly 40, the detonator hull 902 of the detonator 900 abuts the booster hull 80 of the contact kit 70 to allow for ballistic and electrical communication between the detonator 900 and the contact kit 70.

[0041] With the tandem sub 10 coupled to the second perforating gun 30, the bulkhead 50 may be inserted into the bore 14 and secured by the retainer nut 52. Upon inserting the bulkhead 50 into the tandem sub 10, a portion of the bulkhead 50, for example, the contact pin 54a, may extend within the inner chamber 54 (FIG. 3) of the insulative head 43 of the insulative housing assembly 40. The first perforating gun 20 may then be attached to the tandem sub 10 with the first contact kit 60 secured between the bulkhead 50 and the end plate 26 of the charge tube 24.

[0042] FIGS. 8-12 show at least some possible applications of exemplary embodiments of the structures described above. FIG. 8 shows an exemplary embodiment of a cutter assembly 400 that includes a detonator 900 and bulkhead 50 similar to those discussed above in combination with a cross-over sub 402. FIG. 9 shows an exemplary embodiment of a tandem sub 10 having a bulkhead 50 and a detonator 900 positioned between a first perforating gun 20 and a second perforating gun 30. FIG. 10 shows an exemplary embodiment of a tandem sub 500 having a bulkhead 50 and a detonator 900 positioned between a quick change assembly 502 and a first perforating gun 20. The quick change assembly 502 may include a cross-over sub 504 and a sleeve 506 threadedly engaged with the tandem sub 500. FIG. 11 shows an exemplary embodiment of a 60 mm system including a tandem sub 600 having a bulkhead 50 and a detonator 900 positioned between a first perforating gun 20 and a second perforating gun 30. FIG. 12 shows an exemplary embodiment of a 60 mm system including a tandem sub 700 having a bulkhead 50 and a detonator 900 positioned between a cross-over sub 702 and a first perforating gun 20.

[0043] This disclosure, in various embodiments, configurations and aspects, includes components, methods, processes, systems, and/or apparatuses as depicted and described herein, including various embodiments, sub-combinations, and subsets thereof. This disclosure contemplates, in various embodiments, configurations and aspects, the actual or optional use or inclusion of, e.g., components or processes as may be well-known or understood in the art and consistent with this disclosure though not depicted and/or described herein.

[0044] In this specification and the claims that follow, reference will be made to a number of terms that have the following meanings. The terms "a" (or "an") and "the" refer to one or more of that entity, thereby including plural referents unless the context clearly dictates otherwise. As such, the terms "a" (or "an"), "one or more" and "at least one" can be used interchangeably herein. Furthermore, references to "one embodiment", "some embodiments", "an embodiment" and the like are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term such as "about" is not to be limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Terms such as "first," "second," "upper," "lower" etc. are used to identify one element from another, and unless otherwise specified are not meant to refer to a particular order or number of elements.

[0045] As used herein, the terms "may" and "may be" indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of "may" and "may be" indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances the modified term may sometimes not be appropriate, capable, or suitable. For example, in some circumstances an event or capacity can be expected, while in other circumstances the event or capacity cannot occur - this distinction is captured by the terms "may" and "may be."

[0046] As used in the claims, the word "comprises" and its grammatical variants logically also subtend and include phrases of varying and differing extent such as for example, but not limited thereto, "consisting essentially of' and "consisting of." Where necessary, ranges have been supplied, and those ranges are inclusive of all sub-ranges therebetween. It is to be expected that the appended claims should cover variations in the ranges except where this disclosure makes clear the use of a particular range in certain embodiments.

[0047] The terms "determine", "calculate" and "compute," and variations thereof, as used herein, are used interchangeably and include any type of methodology, process, mathematical operation or technique.

[0048] This disclosure is presented for purposes of illustration and description. This disclosure is not limited to the form or forms disclosed herein. In the Detailed Description of this disclosure, for example, various features of some exemplary embodiments are grouped together to representatively describe those and other contemplated embodiments, configurations, and aspects, to the extent that including in this disclosure a description of every potential embodiment, variant, and combination of features is not feasible. Thus, the features of the disclosed embodiments, configurations, and aspects may be combined in alternate embodiments, configurations, and aspects not expressly discussed above. For example, the features recited in the following claims lie in less than all features of a single disclosed embodiment, configuration, or aspect. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this disclosure.

[0049] Advances in science and technology may provide variations that are not necessarily express in the terminology of this disclosure although the claims would not necessarily exclude these variations.