RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63/197,257, filed June 4, 2021.

BACKGROUND

[0002] Generally, when completing a subterranean well for the production of fluids, minerals, or gases from underground reservoirs, several types of tubulars are placed downhole as part of the drilling, exploration, and completions process. These tubulars can include casing, tubing, pipes, liners, and devices conveyed downhole by tubulars of various types. Each well is unique, so combinations of different tubulars may be lowered into a well for a multitude of purposes.

[0003] A subsurface or subterranean well transits one or more formations. The formation is a body of rock or strata that contains one or more compositions. The formation is treated as a continuous body. Within the formation hydrocarbon deposits may exist. Typically, a wellbore will be drilled from a surface location, placing a hole into a formation of interest. Completion equipment will be put into place, including casing, tubing, and other downhole equipment as needed. Perforating the casing and the formation with a perforating gun is a well-known method in the art for accessing hydrocarbon deposits within a formation from a wellbore.

[0004] Explosively perforating the formation using a shaped charge is a widely known method for completing an oil well. A shaped charge is a term of art for a device that when detonated generates a focused output, high energy output, and/or high velocity jet. This is achieved in part by the geometry of the explosive in conjunction with an adjacent liner. Generally, a shaped charge includes a metal case that contains an explosive material with a concave shape, which has a thin metal liner on the inner surface. Many materials are used for the liner; some of the more common metals include brass, copper, tungsten, and lead. When the explosive detonates, the liner metal is compressed into a super-heated, super pressurized jet that can penetrate metal, concrete, and rock. Perforating charges are typically used in groups. These groups of perforating charges are typically held together in an assembly called a perforating gun. Perforating guns come in many styles, such as strip guns, capsule guns, port plug guns, and expendable hollow carrier guns. [0005] Perforating charges are typically detonated by a detonating cord in proximity to a priming hole at the apex of each charge case. Typically, the detonating cord terminates proximate to the ends of the perforating gun. In this arrangement, an initiator at one end of the perforating gun can detonate all the perforating charges in the gun and continue a ballistic transfer to the opposite end of the gun. In this fashion, numerous perforating guns can be connected end to end with a single initiator detonating all of them.

[0006] The detonating cord is typically detonated by an initiator triggered by a firing head. The firing head can be actuated in many ways, including but not limited to electronically, hydraulically, and mechanically.

[0007] Expendable hollow carrier perforating guns are typically manufactured from standard sizes of steel pipe with a box end having intemal/female threads at each end. Pin ended adapters, or subs, having male/external threads are threaded one or both ends of the gun. These subs can connect perforating guns together, connect perforating guns to other tools such as setting tools and collar locators, and connect firing heads to perforating guns. Subs often house electronic, mechanical, or ballistic components used to activate or otherwise control perforating guns and other components.

[0008] Perforating guns typically have a cylindrical gun body and a charge tube or loading tube that holds the perforating charges. The gun body typically is composed of metal and is cylindrical in shape. Charge tubes can be formed as tubes, strips, or chains. The charge tubes will contain cutouts called charge holes to house the shaped charges.

SUMMARY OF EXAMPLE EMBODIMENTS

[0009] An example embodiment may include a perforating gun system having a first perforating gun having a housing with a first end, a second end with first alignment mechanism, and a first set of scallops aligned with the alignment mechanism, a second perforating gun having a housing with a first end with a second alignment mechanism coupled to the first alignment mechanism of the second end of the first perforating gun, and a second set of scallops aligned with the second alignment mechanism, wherein the coupling of the first perforating gun to the second perforating gun aligns the first set of scallops with the second set of scallops.

[0010] A variation of the example embodiment may include the first alignment mechanism being timed male threads. The second alignment mechanism may be timed male threads. It may have at least one o-ring seal between the second end of the first perforating gun and the first end of the second perforating gun. It may have a positive stop at the point of full engagement between the second end of the first perforating gun and the first end of the second perforating gun. The positive stop may be an angled face that resists rotation beyond a predetermined point of thread engagement. The positive stop may be a 45-degree angled face. The timed male threads and timed female threads may be self-sealing. It may include a positive stop at the point of full engagement between the second end of the first perforating gun and the first end of the second perforating gun. The positive stop may be an angled face that resists rotation beyond a predetermined point of thread engagement. The positive stop may be a 45-degree angled face.

[0011] An example embodiment may include a perforating gun system having a first perforating gun having a housing with a first end, a second end with timed male threads, and a first set of scallops aligned with the timed male threads, a second perforating gun having a housing with a first end with timed female threads coupled to the second end of the first perforating gun with timed threads, and a second set of scallops aligned with the timed female threads, wherein the full engagement of the timed male timed with the timed female threads aligns the first set of scallops with the second set of scallops.

[0012] A variation of the perforating gun system may include at least one o-ring seal between the second end of the first perforating gun and the first end of the second perforating gun. It may include a positive stop at the point of full engagement between the second end of the first perforating gun and the first end of the second perforating gun. The positive stop may be an angled face that resists rotation beyond a predetermined point of thread engagement. The positive stop may be a 45-degree angled face. The timed male threads and timed female threads may be self- sealing.

[0013] An example embodiment may include a method for assembling a perforating gun string including threading a first timed threads of a first perforating gun into a second timed threads of a second perforating gun, aligning a first set of scallops on the first perforating gun with a second set of scallops on a second perforating gun, engaging the first timed threads of the first perforating gun with the second timed threads of the second perforating gun fully, wherein the full engagement of the first perforating gun with the second perforating gun aligns the first set of scallops with the second set of scallops. [0014] A variation of the example embodiment may include engaging a positive stop when engaging the first timed threads of the first perforating gun with the second timed threads of the second perforating gun. It may include the full engagement of the first perforating gun with the second perforating gun provides a pressure seal between the inside of the perforating gun string and the outside of the perforating gun string.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] For a thorough understanding of the example embodiments, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings in which reference numbers designate like or similar elements throughout the several figures of the drawing. Briefly:

FIG. l is a side view of a perforating gun with self-sealing tapered threads.

FIG.2 is a partially transparent view of a perforating gun with self-sealing tapered threads. FIG.3 is a cutaway view of two perforating guns with timed self-sealing tapered threads connected to each other.

FIG.4 is a cutaway view of a perforating gun with self-sealing tapered threads.

FIG.5 is a cutaway view of the connection of two perforating guns with self-sealing tapered threads connected to each other.

FIG.6 is a perspective view of two perforating guns with timed self-sealing tapered threads connected to each other.

FIG.7 is a perspective view of the connection of two perforating guns with timed self sealing tapered threads connected to each other.

FIG.8 is a partial cutaway view of the connection of two perforating guns with timed self- sealing tapered threads connected to each other.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0016] In the following description, certain terms have been used for brevity, clarity, and examples. No unnecessary limitations are to be implied therefrom and such terms are used for descriptive purposes only and are intended to be broadly construed. The different apparatus, systems and method steps described herein may be used alone or in combination with other apparatus, systems and method steps. It is to be expected that various equivalents, alternatives, and modifications are possible within the scope of the appended claims.

[0017] Terms such as booster may include a small metal tube containing secondary high explosives that are crimped onto the end of detonating cord. The explosive component is designed to provide reliable detonation transfer between perforating guns or other explosive devices, and often serves as an auxiliary explosive charge to ensure detonation.

[0018] Detonating cord is a cord containing high-explosive material sheathed in a flexible outer case, which is used to connect the detonator to the main high explosive, such as a shaped charge. This provides an extremely rapid initiation sequence that can be used to fire several shaped charges simultaneously.

[0019] A detonator or initiation device may include a device containing primary high-explosive material that is used to initiate an explosive sequence, including one or more shaped charges. Two common types may include electrical detonators and percussion detonators. Detonators may be referred to as initiators. Electrical detonators have a fuse material that burns when high voltage is applied to initiate the primary high explosive. Percussion detonators contain abrasive grit and primary high explosive in a sealed container that is activated by a firing pin. The impact of the firing pin is sufficient to initiate the ballistic sequence that is then transmitted to the detonating cord.

[0020] Initiators may be used to initiate a perforating gun, a cutter, a setting tool, or other downhole energetic device. For example, a cutter is used to cut tubulars with focused energy. A setting tool uses a pyrotechnic to develop gases to perform work in downhole tools. Any downhole device that uses an initiator may be adapted to use the modular initiator assembly disclosed herein. [0021] As shown in the example embodiments of FIGs 1-8, the perforating guns include housings 10 that have male threads 13 and a baffle 11 at one end (the pin end) and female threads 40 at the other end (the box end). The threads are of a tapered and/or self-sealing variety. This allows the perforating gun housing 10 to provide a pressure seal between the interior and exterior of the housing 10 without relying on o-rings. This allows for simplification of manufacturing and associated costs by reducing the number of machining operations necessary to manufacture the perforating gun housing 10. This also allows for simplification of the assembly of the perforating gun and associated costs by reducing the number of parts and operations required. [0022] The male and female threads may also be timed (also referred to as clocked) so that the scallops 12 and/or perforating charges of adjacent perforating guns are aligned with each other when the threaded connection between guns is made up. Having the threaded connection timed to align the perforating charges and/or scallops 12 of the adjacent perforating guns allows the orientation of an entire string of perforating guns without the use of alignment or orienting subs and/or locking collars between perforating guns.

[0023] Perforating guns often, but not always have scallops 12, or machined thin wall areas, that are aligned with the exiting jet of the perforating shaped charges. The examples of this description could be made with or without scallops 12.

[0024] As seen in FIG. 3, the perforating guns each include a charge tube 15, 25 within each gun housing 10, 20 respectively. Between each perforating gun is a pressure bulkhead 11. In this example embodiment the first gun housing 10 with scallops 12 engages with the second gun housing 20 with scallops 22. When coupling the tapered threads 13 of the pin end of the first gun housing 10 with the box end threads 43 of the second gun housing 20 there is a contact point where the threads initially make contact that is also aligned with the scallops 12 and 22. The purpose of the pressure bulkhead/baffle 11 is to isolate the interior of each perforating gun from pressure that may be present in the interior of adjacent perforating guns. This pressure can be caused by leaking of wellbore pressure into the interior of a perforating gun, pressure from detonation of explosives within a perforating gun, or equalization of wellbore pressure into a perforating gun housing 10 through holes made by perforating charges. Typically, o-rings provide the pressure seal between the pressure bulkhead/baffle 11 and the perforating gun carrier or housing 10. The second perforating gun housing 20 has a second bulkhead 21 for coupling to a third perforating gun housing.

[0025] In the example of FIG. 4, an o-ring groove is seen in the bulkhead 11 that could be used to provide a pressure seal between the baffle 11 and perforating gun housing 10. A top end fitting 16 on the loading tube holds an integral selective perforating switch. Such a switch is generally addressable to allow selective detonation of a single perforating gun in the string. The switch may also include an orientation detector, such as a gyroscope and/or an accelerometer that provides data regarding the orientation of the switch and, correspondingly, the perforating charges. In the example of FIG. 4, a pressure bulkhead/bottom contact within the bulkhead 11 provides an electrical connection on the bottom of the perforating gun that connects to the interior of the perforating gun housing 20, such as to the switch. The top end fitting 16 in concert with the bulkhead 11 provides a pressure seal between the interior of the perforating gun housing 10 and the wellbore or an adjacent perforating gun. The top end fitting 16 also includes a top contact providing electrical connections on the top of the perforating gun that connect to the interior of the perforating gun, such as to the switch. The charge tube 15 includes cutouts 19 for installation of shaped charges.

[0026] Alternatively, the perforating gun may not include a switch. In that example, the electrical connections would still pass electrical signals from one perforating gun to another without the presence of a switch in each perforating gun.

[0027] FIG. 5 shows a detailed view of the connection between two perforating guns. The first perforating gun housing 10, having tapered threads 13, is coupled to the second perforating gun housing 20, having female threads 43. In this example, the bulkhead 11 includes a larger diameter sealing portion having a shoulder on each side. These shoulders then engage corresponding shoulders 31 on the adjacent perforating gun housing 20. This captures the sealing portion of the bulkhead 11 between the two adjacent perforating gun housings 10, 20. This engagement provides a metal-to-metal high pressure seal 33 between adjacent perforating guns. Such an arrangement obviates the necessity of exterior/external o-rings. FIG. 5 also shows the seal provided by tapered self-sealing threads in adjacent gun carriers. End fitting 17 is shown supporting the charge tube 15. The bottom contact 18 provides electrical communication through the bulkhead 11. The spring 32 provides additional contact support within the bulkhead 11. The end fitting 26 supports the charge tube 25 with shaped charge cutouts 29.

[0028] These example features are further shown in FIGs 6-8. A first perforating gun housing 10 is coupled to a second perforating gun housing 20. The scallops 12 and 22 are aligned. The alignment is provided by the timed threads. The gun carrier may include a positive stop 45 aligned with the scallops 12 and 22 to provide specific engagement for timing the threads on adjacent gun housings to ensure the alignment of the scallops 12 and 22 when the two perforating gun housings 10 and 20 reach their engagement point 34. The positive stop 45 may be a face angled relative to the long axis of the gun carrier 50. In that case, torque applied when making up the threaded joint between adjacent perforating gun housings 10 and 20 can be converted to axial force, thus improving engagement between the threads of adjacent gun carriers, and further improving sealing and pressure resistance. In some examples, the angle of the positive stop 45 may be 45 degrees. [0029] In some examples, not all of these features will be present. In various examples, the key features may be present in any combination. For example, a tool string may have perforating guns with timed threads that are not necessarily self-sealing and may use traditional sealing mechanisms such as o-rings. In another example, a tool string may have perforating guns without timed threads, but whose threads are self-sealing and may not use traditional sealing mechanisms such as o-rings. In another example, a tool string may include perforating guns that have a positive stop, or a positive stop with an angled face, without requiring timed threads and self-sealing threads, or without either timed threads or self-sealing threads.

[0030] These improvements could also be combined with an orientation sensor or orientation sensing switch to provide confirmation of each perforating guns orientation before firing and/or when fired.

[0031] Although the example embodiments have been described in terms of embodiments which are set forth in detail, it should be understood that this is by illustration only and that the example embodiments are not necessarily limited thereto. For example, terms such as upper and lower or top and bottom can be substituted with uphole and downhole, respectfully. Top and bottom could be left and right, respectively. Uphole and downhole could be shown in figures as left and right, respectively, or top and bottom, respectively. Generally downhole tools initially enter the borehole in a vertical orientation, but since some boreholes end up horizontal, the orientation of the tool may change. In that case downhole, lower, or bottom is generally a component in the tool string that enters the borehole before a component referred to as uphole, upper, or top, relatively speaking. The first housing and second housing may be top housing and bottom housing, respectfully. In a gun string such as described herein, the first gun may be the uphole gun or the downhole gun, same for the second gun, and the uphole or downhole references can be swapped as they are merely used to describe the location relationship of the various components. Terms like wellbore, borehole, well, bore, oil well, and other alternatives may be used synonymously. Terms like tool string, tool, perforating gun string, gun string, or downhole tools, and other alternatives may be used synonymously. The alternative embodiments and operating techniques will become apparent to those of ordinary skill in the art in view of the present disclosure. Accordingly, modifications of the example embodiments are contemplated which may be made without departing from the spirit of the claimed example embodiments.