Perforating Gun and Method of Using Same

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

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.

FIELD OF THE INVENTION

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.

BACKGROUND

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.

SUMMARY OF THE INVENTION

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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section view of a perforating gun according to an embodiment of the invention.

FIG. 2 is another section view of the perforating gun of FIG. 1.

FIG. 3 is a perspective view of a two-shot perforating gun according to an embodiment of the invention.

FIG. 4 is a side view of the two-shot perforating gun of FIG. 3.

FIG. 5 is an exploded view of the two-shot perforating gun of FIG. 3.

FIG. 6 is a section view of the two-shot gun of FIG. 3.

FIG. 7 is another section view of the two-shot gun of FIG. 3 wherein the gun is threadably connected to a tandem sub.

FIG. 8 is a side view of the two-shot gun of FIG. 3, wherein the gun is situated within a gun barrel.

FIG. 9 is an exploded perspective view of a switch housing for a perforating gun according to an embodiment of the invention.

FIG. 10A is a bottom view of the switch housing of FIG. 9.

FIG. 10B is a top view of the switch housing of FIG. 9.

FIG. 11A is an exploded view of a pin contact assembly for a perforating gun according to an embodiment of the invention.

FIG. 11B is a bottom view of the pin contact assembly of FIG. 11A.

FIG. 11C is a side view of the pin contact assembly of FIG. 11A.

FIG. 12 is an exploded view of another embodiment of a two-shot perforating gun with a gun barrel.

FIG. 13 is a top view of the two-shot perforating gun according to FIG. 12.

FIG. 14 is a bottom view of the two-shot perforating gun according to FIG. 12.

FIG. 15 is a right-side view of the two-shot perforating gun according to FIG. 12.

FIG. 16 is a left-side view of the two-shot perforating gun according to FIG. 12.

FIG. 17 is a perspective view of a six-shot perforating gun according to an embodiment of the invention.

FIG. 18 is a perspective view of the six-shot perforating gun of FIG. 17 with the shaped charges removed.

FIG. 19 is a side view of the six-shot perforating gun of FIG. 18.

FIG. 20 is a side view of the six-shot perforating gun of FIG. 17.

WRITTEN DESCRIPTION

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 FIGS. 1-2, the invention includes a perforating gun system 100 with a gun barrel 102, a tandem sub 104, a charge tube 106 configured to be situated inside the barrel 102 and which holds shaped charges 108, an addressable switch assembly 110 configured to fire the gun cluster at a specific time, and a pin contact assembly 112.

FIG. 8 shows a gun barrel 102 according to embodiments of the invention. As is generally known in the art, the gun barrel 102 is a tube, typically steel, having a diameter that is slightly larger than the charge tube 106. The gun barrel 102 usually has areas of indentation 103 that correspond generally with the location of the shaped charge(s) 108 when the charge tube 106 is situated within the barrel 102. The areas of indentation 103 allow the explosive energy of the shaped charges 108 to more easily penetrate through the wall of the barrel 102 and into the casing of the well and ultimately the rock formation.

The tandem sub 104 includes 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 sub 104 correspond to threads on the inside surface of the gun barrel 102. When a charge tube 106 is inserted into the barrel 102 (along with any necessary charge tube end assemblies) thereby forming a gun assembly, a tandem sub 104 may be threadably attached to each end of the barrel such that additional gun assemblies can be attached in series as desired. The tandem sub 104 may also allow for the barrel 102 to attach to other tools along the wireline as is known in the art. O-rings, which may be located between the tandem sub 104 and the gun barrel 102 may provide a seal between the sub 104 and the barrel 102.

Referring now to FIGS. 3-7, the charge tube 106 is designed to hold the shaped charges 108. Generally speaking, the charge tube 106 is generally cylindrical and includes cutouts where the shaped charges 108 are placed. As is known to those of skill in the art, the shaped charges 108 may be held within the charge tube 106 via tabs which are folded into place once the shaped charge 108 is placed within the tube 106. An end of the shaped charge 108 may extend through an opening in the tube 106, and the detonation cord may be threaded through the end(s) of the shaped charge(s) 108 held within the tube 106 to facilitate detonation of the shaped charges 108 at 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 106. 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 106, like typical charge tubes, has openings 106a into which the shaped charges 108 are placed. Unlike prior art guns, however, the charge tube 106 may be equipped with one or more weights 114 which is or are attached to the charge tube 106 via tabs that fold and lock into place (similar to how the shaped charges 108 are held in place). Alternatively, the weight(s) 114 may have an inside diameter profile that is substantially the same as the outer diameter profile of the charge tube 106 such that the weight 114 may hug the tube 106 at (a) predetermined location(s) (e.g., at an underside of the tube) and the weight(s) 114 may be attached to the tube 106 via one or more rivets 115 or other mechanical fasteners.

Importantly, and as shown in FIG. 4, the one or more weights 114 are thin enough that they do not extend past the outermost surfaces 1120 and 1100 of the pin contact assembly 112 and the addressable switch assembly 110, respectively. This ensures that, together with other functionalities of the gun assembly 100, the charge tube 106 can freely rotate within the barrel 102 thereby allowing the charge tube 106 to self-orient within the barrel 102 based on the placement of the weight(s) 114 and the effects of gravity.

Moving on to FIGS. 12-20, in some embodiments, it may not be feasible to place weight(s) 114 on the charge tube 106. For example, in small guns, there may not be enough room for a weight 114 on the charge tube 106, or the weight 114 that could be attached would not be large (e.g., heavy) enough to substantially and/or effectively impact the orientation of the charge tube 106 downhole. Accordingly, in embodiments, it may be preferable for the charge tube 106 to be redesigned in such a way that the charge tube 106 can still self-orient without the need for attaching weights 114 thereto.

FIG. 12 shows an exploded view of a charge tube 106′ that is ready for installation into a barrel 102. Here, the charge tube 106′ has openings 106a′ for receiving shaped charges 108 as with standard charge tubes. However, unlike other charge tubes, sections 109 of the charge tube 106′ have been removed from the top side of the tube 106′ to reduce the amount of material on the top side of the tube 106′. The bottom side of the tube 106′, as shown in FIG. 14, remains substantially unchanged.

By removing material from the top side of the charge tube 106′ and leaving the bottom side unchanged, the bottom side effectively becomes a weight and allows the charge tube 106′ 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 106′ itself in order to ensure that there is sufficient weight on the bottom to allow the charge tube 106′ 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.

FIGS. 13-16 show a charge tube 106′ designed to hold two shaped charges 108. However, it may be possible, and even preferable, to utilize a reduced-material charge tube 106′ as described herein for larger guns. In particular, FIGS. 17-20 show an embodiment of the charge tube 106′ which is designed to incorporate six shaped charges 108.

Metal coil springs 116 may be attached to the charge tube 106, 106′ for grounding purposes. The metal springs 116 facilitate contact from the charge tube 106, 106′ to the gun barrel 102, which carries the ground signal for communication. Preferably, the stiffness of the springs 116 is such that the springs 116 can easily flex when the charge tube 106, 106′ is placed into the barrel 102 and the springs 116 do not get caught on the inner surface of the barrel 102.

Moving on, the addressable switch assembly 110 is illustrated in FIGS. 9 and 10A-B. The addressable switch assembly 110, shown in an exploded view in FIG. 9, includes a switch housing 118 which houses an addressable switch 120. The addressable switch 120 receives a coded signal to detonate gun clusters in a specified order. An opening 121 in the switch housing 118 receives a spring 122 which biases a contact terminal 124 toward the opening 121. A bushing 126 keeps the contact terminal 124 within the opening 121. Another opening in the housing 118, not shown in the drawings, holds the detonator 128. The addressable switch assembly 110 may further include an interrupter 130 which includes an interrupter shield tubing 131 and a pull tab 132. The shield tubing 131 extends into still another opening in the housing 118, also not shown in the drawings, which prevents the detonator 128 from activating the detonation cord unintentionally. Because of the interrupter 130, and specifically the interrupter shield tubing 131, it may be possible to install both the detonator 128 and 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 detonator 128 has to be inserted in the field. In some cases, the gun has to be partially disassembled in order to insert the detonator 128 and/or to complete the necessary electrical connections. If the detonator 128 is 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 detonator 128 on-sight, thus reducing field errors.

The pull tab 132 includes a portion 132a which extends over the contact terminal 124 and serves as an electrical signal interrupter to prevent communication between guns. If the interrupter 130 is not removed prior to assembling the gun system 100, 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 interrupter 130 can be easily removed by pulling it away from the switch housing 118. An upper gun can then be mated with a lower gun whereby the pin contact assembly 112 of the lower gun engages with the switch contact terminal 124 in the switch housing 118 of the upper gun.

Referring now to FIGS. 11A-11C, the pin contact assembly 112 is illustrated. As shown in the exploded view of FIG. 11A, the pin contact assembly 112 includes a contact spacer 134. A roller bearing 136 is optionally situated within the contact spacer 134, and a through pin 138 extends through the contact spacer 134 and attaches to the pin contact 140. The pin contact 140 includes a plastic overmold 142 over a brass core 144. The through pin 138 connects to the pin contact 140, e.g., via a snap fit, friction fit, threads, or the like. In an installed position, the through pin 138 sits atop the roller bearing 136 thereby allowing the pin contact 140 to rotate freely.

A proximal end 146a of an offset coil contact spring 146 rests atop the through pin 138. A distal end 146b of the offset coil contact spring 146 is centered over a hole 135 in the contact spacer 134. A ring terminal 148 connected to an end of the through wire is placed over the distal end 146b of the offset coil contact spring 146 and a rivet 150 (or other fastener) holds the through wire ring terminal 148 and the contact spring distal end 146b in place. Electrical communication is facilitated via the through pin 138, which passes a signal through the offset coil contact spring 146 to the through wire via the through wire ring terminal 148.

The pin contact assembly 112, among other things, may additionally provide pressure isolation between the gun and a plug-setting tool via o-rings 143 on the through pin housing 142. Additionally, when the gun fires, the through pin 138 may 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.