Perforating Gun and Method of Using Same

This application claims the benefit of priority of U.S. Provisional Patent Application No. 63/683,908, filed Aug. 16, 2024. This application is also a continuation-in-part of U.S. patent application Ser. No. 18/746,027, filed Jun. 17, 2024, which is a continuation of U.S. patent application Ser. No. 17/454,777, filed Nov. 12, 2021, now U.S. Pat. No. 12,012,829 which issued Jun. 18, 2024, which is a continuation-in-part of U.S. patent application Ser. No. 17/518,159, filed Nov. 3, 2021, which is abandoned, and which is a continuation-in-part of U.S. patent application Ser. No. 17/182,420, filed Feb. 23, 2021, which is abandoned and claims the benefit of priority of U.S. Provisional Patent Application No. 62/982,217, filed Feb. 27, 2020. U.S. Patent Application '777 also claims priority to U.S. Provisional Patent Application No. 63/263,377, filed Nov. 1, 2021. The disclosure of each of these applications is incorporated by reference herein in its entirety.

The invention relates to perforating guns utilized in fracturing for oil and gas.

More particularly, the invention is directed to a self-orienting gun system that will automatically point the shape charge in the desired direction without further intervention and corresponding methods.

Hydraulic fracturing is a well stimulation technique in which rock is fractured by a pressurized liquid. The process involves the high-pressure injection of fracturing fluid (primarily water containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of proppant hold the fractures open.

Once the well is drilled and cased, the casing must be perforated before fracturing can occur. Perforating gun systems have been used in oil and gas exploration for many years in order to create holes in the wellbore casing to the subterranean rock in order to provide a flow path for the hydrocarbons (oil and gas) trapped in the well. In order to make these holes, explosives are used to create a blast of energy that cuts through metal tubulars, cement, and some distance into the rock containing oil and gas. Perforating gun systems can be conveyed on wireline that is connected to a specialty wireline truck or coil tubing that is managed on a rig on the surface.

In the case of hydraulic fracturing operations of oil and gas wells, a perforating tool string is typically deployed on wireline and comprises a pressure isolation plug on bottom, the plug setting tool, a string of guns, a means for mechanically disconnecting wireline from guns, and a collar locator that is used for depth control. The tool string is connected to the wireline with a cable head that provides mechanical connection of the tool string as well as an electrical connection.

Sometimes additional pieces, such as weight bars, are connected to the tool string to provide additional weight to the string for stability when the wireline tools are near the wellhead and also to increase speed of deployment of the wireline when being deployed to total depth.

One individual perforating gun is referred to as a cluster and multiple clusters make up a string. One well typically requires the fracturing and perforating operations to occur multiple times to complete the well prior to allowing oil and gas to flow out of the well. The perforating operation typically requires an isolation plug to be set below the targeted zone first, then multiple clusters are shot in order to provide several entry points through the targeted zone. The shots are fired from the bottom of the tool string to the top and each event is considered to be destructive to that cluster so most parts are not reusable upon completion.

In many instances, it is desirable to orient the gun, and particularly the shaped charge, in a particular way such that the charges are directed to a specific location along the casing. Given that the gun may be several thousands of feet away from the surface controls, this can be challenging. To simplify the process of orienting the gun, it is desirable to provide a self-orienting gun system configured to automatically point the shape charge in the desired direction without further intervention.

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not intended to identify critical elements of the invention or to limit the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description provided below.

In one embodiment, a perforating gun includes a gun assembly and a gun barrel. The gun assembly includes a charge tube comprising at least one shaped charge. A pin contact assembly is operably attached to a first end of the charge tube and includes a contact spacer and a through pin configured to provide electrical communication between respective perforating guns. An addressable switch assembly is attached to a second end of the charge tube and comprises an addressable switch and a detonator. The gun assembly is situated within the gun barrel and is configured to self-orient inside the gun barrel.

In another embodiment, a perforating gun includes a gun assembly and a gun barrel. The gun assembly includes a charge tube comprising at least one shaped charge; a pin contact assembly operably attached to a first end of the charge tube, and an addressable switch assembly attached to a second end of the charge tube. The pin contact assembly has a contact spacer and a through pin configured to provide electrical communication between perforating gun. The contact spacer comprises a roller bearing and the through pin is operably associated with the roller bearing such that the through pin can freely rotate along an axis of the gun assembly. The addressable switch assembly includes an addressable switch and a detonator. The gun assembly is situated within and is configured to self-orient inside the gun barrel.

In still another embodiment, a perforating gun includes a gun assembly, comprising a charge tube comprising at least one shaped charge; and a gun barrel. The gun assembly is situated within and is configured to self-orient inside the gun barrel.

The claimed invention is directed towards a new and improved gun and method of use by providing a self-orienting gun system. As such, the general purpose of the invention, which will be described subsequently in greater detail, is to provide a new and improved perforating gun for fracturing and method of using the same.

In general, and referring to, the invention includes a perforating gun systemwith a gun barrel, a tandem sub, a charge tubeconfigured to be situated inside the barreland which holds shaped charges, an addressable switch assemblyconfigured to fire the gun cluster at a specific time, and a pin contact assembly.

shows a gun barrelaccording to embodiments of the invention. As is generally known in the art, the gun barrelis a tube, typically steel, having a diameter that is slightly larger than the charge tube. The gun barrelusually has areas of indentationthat correspond generally with the location of the shaped charge(s)when the charge tubeis situated within the barrel. The areas of indentationallow the explosive energy of the shaped chargesto more easily penetrate through the wall of the barreland into the casing of the well and ultimately the rock formation.

The tandem subincludes opposing threaded ends and is designed to connect perforating guns in series for oil and gas well operations. Generally speaking, the threads on the ends of the tandem subcorrespond to threads on the inside surface of the gun barrel. When a charge tubeis inserted into the barrel(along with any necessary charge tube end assemblies) thereby forming a gun assembly, a tandem submay be threadably attached to each end of the barrel such that additional gun assemblies can be attached in series as desired. The tandem submay also allow for the barrelto attach to other tools along the wireline as is known in the art. O-rings, which may be located between the tandem suband the gun barrelmay provide a seal between the suband the barrel.

Referring now to, the charge tubeis designed to hold the shaped charges. Generally speaking, the charge tubeis generally cylindrical and includes cutouts where the shaped chargesare placed. As is known to those of skill in the art, the shaped chargesmay be held within the charge tubevia tabs which are folded into place once the shaped chargeis placed within the tube. An end of the shaped chargemay extend through an opening in the tube, and the detonation cord may be threaded through the end(s) of the shaped charge(s)held within the tubeto facilitate detonation of the shaped chargesat the desired time.

Notably, in prior art perforation gun systems, orienting subs, swivels, and/or eccentric weight bars may have been required in order to control orientation of the charge tube. However, these orienting mechanisms are often unreliable, inefficient, and/or uneconomic. Moreover, these orienting mechanisms are often externally mounted, which can increase the complexity of the gun assembly, and often add length to the gun assembly making the gun assembly more difficult to ship and control once deployed into the well.

According to the invention, the charge tube, like typical charge tubes, has openingsinto which the shaped chargesare placed. Unlike prior art guns, however, the charge tubemay be equipped with one or more weightswhich is or are attached to the charge tubevia tabs that fold and lock into place (similar to how the shaped chargesare held in place). Alternatively, the weight(s)may have an inside diameter profile that is substantially the same as the outer diameter profile of the charge tubesuch that the weightmay hug the tubeat (a) predetermined location(s) (e.g., at an underside of the tube) and the weight(s)may be attached to the tubevia one or more rivetsor other mechanical fasteners.

Importantly, and as shown in, the one or more weightsare thin enough that they do not extend past the outermost surfacesandof the pin contact assemblyand the addressable switch assembly, respectively. This ensures that, together with other functionalities of the gun assembly, the charge tubecan freely rotate within the barrelthereby allowing the charge tubeto self-orient within the barrelbased on the placement of the weight(s)and the effects of gravity.

Moving on to, in some embodiments, it may not be feasible to place weight(s)on the charge tube. For example, in small guns, there may not be enough room for a weighton the charge tube, or the weightthat could be attached would not be large (e.g., heavy) enough to substantially and/or effectively impact the orientation of the charge tubedownhole. Accordingly, in embodiments, it may be preferable for the charge tubeto be redesigned in such a way that the charge tubecan still self-orient without the need for attaching weightsthereto.

shows an exploded view of a charge tube′ that is ready for installation into a barrel. Here, the charge tube′ has openings′ for receiving shaped chargesas with standard charge tubes. However, unlike other charge tubes, sectionsof the charge tube′ have been removed from the top side of the tube′ to reduce the amount of material on the top side of the tube′. The bottom side of the tube′, as shown in, remains substantially unchanged.

By removing material from the top side of the charge tube′ and leaving the bottom side unchanged, the bottom side effectively becomes a weight and allows the charge tube′ to self-orient without requiring a weight. Although it may not be necessarily required in all scenarios, it may be preferable to increase the thickness of the charge tube′ itself in order to ensure that there is sufficient weight on the bottom to allow the charge tube′ to self-orient. There are many advantages to a self-orienting charge tube that is constructed by removing material from the top of the tube. For example, there is no requirement to the gun manufacturer to maintain an inventory of weights to attach to the charge tube. Additionally, the time and labor associated with adding additional components to the charge tube may be reduced or, in some cases, eliminated. Surprisingly, manufacturing a self-orienting charge tube as described herein can save significant amounts in parts and labor as compared to common prior art methods of manufacturing. Accordingly, while it is especially convenient for small guns due to the lack of space for attaching weights, it may be preferable to manufacture larger self-orienting guns according to the same methods, i.e., by removing material from the top of the charge tube.

show a charge tube′ designed to hold two shaped charges. However, it may be possible, and even preferable, to utilize a reduced-material charge tube′ as described herein for larger guns. In particular,show an embodiment of the charge tube′ which is designed to incorporate six shaped charges.

Metal coil springsmay be attached to the charge tube,′ for grounding purposes. The metal springsfacilitate contact from the charge tube,′ to the gun barrel, which carries the ground signal for communication. Preferably, the stiffness of the springsis such that the springscan easily flex when the charge tube,′ is placed into the barreland the springsdo not get caught on the inner surface of the barrel.

Moving on, the addressable switch assemblyis illustrated in-B. The addressable switch assembly, shown in an exploded view in, includes a switch housingwhich houses an addressable switch. The addressable switchreceives a coded signal to detonate gun clusters in a specified order. An openingin the switch housingreceives a springwhich biases a contact terminaltoward the opening. A bushingkeeps the contact terminalwithin the opening. Another opening in the housing, not shown in the drawings, holds the detonator. The addressable switch assemblymay further include an interrupterwhich includes an interrupter shield tubingand a pull tab. The shield tubingextends into still another opening in the housing, also not shown in the drawings, which prevents the detonatorfrom activating the detonation cord unintentionally. Because of the interrupter, and specifically the interrupter shield tubing, it may be possible to install both the detonatorand the detonation cord in the shop such that the gun can be transported to the fracking location as a substantially complete unit. This is highly useful because it reduces the time it takes to complete final assembly of the gun system. But perhaps more importantly, field assembly errors can be greatly reduced or even eliminated. In traditional gun systems, the detonatorhas to be inserted in the field. In some cases, the gun has to be partially disassembled in order to insert the detonatorand/or to complete the necessary electrical connections. If the detonatoris inserted incorrectly, or the electrical connections are missing, the gun may not fire, or if it does fire, it may fire incorrectly (e.g., in the wrong direction). To the contrary, if the gun is complete upon arrival at the fracking location, the field operators are not required to insert the detonatoron-sight, thus reducing field errors.

The pull tabincludes a portionwhich extends over the contact terminaland serves as an electrical signal interrupter to prevent communication between guns. If the interrupteris not removed prior to assembling the gun system, the operator will not be able to communication with all of the tools in the string as intended.

In use, when the field operator is ready for final assembly, the interruptercan be easily removed by pulling it away from the switch housing. An upper gun can then be mated with a lower gun whereby the pin contact assemblyof the lower gun engages with the switch contact terminalin the switch housingof the upper gun.

Referring now to, the pin contact assemblyis illustrated. As shown in the exploded view of, the pin contact assemblyincludes a contact spacer. A roller bearingis optionally situated within the contact spacer, and a through pinextends through the contact spacerand attaches to the pin contact. The pin contactincludes a plastic overmoldover a brass core. The through pinconnects to the pin contact, e.g., via a snap fit, friction fit, threads, or the like. In an installed position, the through pinsits atop the roller bearingthereby allowing the pin contactto rotate freely.

A proximal endof an offset coil contact springrests atop the through pin. A distal endof the offset coil contact springis centered over a holein the contact spacer. A ring terminalconnected to an end of the through wire is placed over the distal endof the offset coil contact springand a rivet(or other fastener) holds the through wire ring terminaland the contact spring distal endin place. Electrical communication is facilitated via the through pin, which passes a signal through the offset coil contact springto the through wire via the through wire ring terminal.

The pin contact assembly, among other things, may additionally provide pressure isolation between the gun and a plug-setting tool via o-ringson the through pin housing. Additionally, when the gun fires, the through pinmay move toward the gun above it and may create a seal isolating the wellbore pressure and fluids from the gun not yet shot.

Many different arrangements of the various components depicted herein, as well as components not shown, are possible without departing from the spirit and scope of the invention. Embodiments of the invention have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from its scope. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from the scope of the invention. Further, it will be understood that certain features and subcombinations are of utility and may be employed within the scope of this disclosure. Further, various steps set forth herein may be carried out in orders that differ from those set forth herein without departing from the scope of the claimed methods. The specification shall not be restricted to the above embodiments. Any units of measurement provided herein are exemplary only and are not meant to specifically define the necessary dimensions of the system.