Inverted tail plug and assembly for gas lift valve

Abstract

Embodiments of the present invention relate to an improved tail plug and assembly for a gas lift valve for use in oil and gas wells. The tail plug assists in preventing a pressurized component of the gas lift valve from depressurizing through leaks in the valve to the ambient. At least portion of the tail plug may be maintained in the gas lift valve via a treaded connection. The tail plug may further prevent leaks via an O-ring and / or a crush washer, where the O-ring and / or the crush washer are located on the tail plug below its threaded connection.

Description

PRIORITY CLAIM

[0001] This application claims priority to provisional patent application Ser. No. 63 / 638,282 filed May 13, 2024, which is fully incorporated herein by reference.BACKGROUNDTechnical Field

[0002] Embodiments of the subject matter disclosed herein relate to an improved tail plug and assembly for a gas lift valve for use in oil and gas wells.Discussion of the Background

[0003] Those skilled in the art know that gas lift mandrels and valves play a crucial role in enhancing oil and gas production from wells, particularly in challenging conditions where traditional methods may fall short. These systems utilize the injection of gas to lighten the hydrostatic column of fluid in the wellbore, thereby reducing the pressure required to lift fluids to the surface. This method is especially beneficial in wells with low reservoir pressure or high fluid viscosity, where conventional pumping techniques may struggle.

[0004] At the core of gas lift systems are mandrels, which are tubular devices installed at various depths in the well. These mandrels serve as anchor points for the gas lift valves, which control the injection of gas into the produced fluids. The design of the mandrel allows for easy installation and retrieval of the valves, facilitating maintenance and adjustments without needing to pull the entire tubing string. This flexibility is a significant advantage in maximizing production efficiency and minimizing downtime.

[0005] The gas lift valves are strategically positioned within the mandrels to regulate gas flow based on the relative pressure between lift gas injected into the well and pressure and fluid levels in the well itself. When the reservoir pressure drops or when fluid levels are insufficient for natural flow, the valves can open to allow gas to enter the wellbore. This injection reduces the density of the fluid column, enabling the hydrostatic pressure to be overcome more easily. As a result, the mixture of gas and fluid can be lifted to the surface with less energy.

[0006] A key benefit of using gas lift systems is their adaptability. Operators can adjust the amount and timing of gas injection based on real-time data from the well. This ability to dynamically control production allows for optimization based on varying reservoir conditions, which can significantly improve recovery rates. In essence, gas lift systems can be tailored to fit the specific characteristics of a well, leading to enhanced production efficiency.

[0007] Another advantage of gas lift technology is its lower operational costs compared to other artificial lift methods. Unlike electric submersible pumps (ESPs) or rod pumps, gas lift systems do not require extensive electrical infrastructure or complex mechanical components. This simplicity translates to reduced maintenance costs and fewer failures, making gas lift an attractive option for operators seeking to minimize expenses while maximizing output.

[0008] Moreover, gas lift systems can be deployed in environments where other artificial lift methods may be impractical. For instance, in offshore applications or remote locations with limited access to power sources, gas lift provides a reliable alternative that can be implemented with minimal logistical challenges. This versatility enables operators to extend the productive life of their wells and make the most of available resources.

[0009] As the oil and gas industry continues to evolve, the integration of advanced monitoring and control technologies with gas lift systems offers evolving possibilities. By incorporating sensors and real-time data analytics, operators can achieve even greater precision in managing gas injection and production rates. This integration can lead to improved recovery factors and more efficient use of reservoir resources, ultimately enhancing the economic viability of oil and gas projects.

[0010] Heretofore, however, gas lift valves have suffered leaks that diminish the efficiency and operability of the valves themselves. As those skilled in the art know, the ability of a gas lift valve to maintain a predetermined (or set) pressure level is important to the efficient operation of the valve in a well. Indeed, beyond mere inefficiencies, valve failures can result in costly delays and equipment costs if the valve(s) must be replaced.

[0011] FIGS. 1 and 2 are perspective views of a gas lift valve 10. The top or upper portion of the valve, i.e., the portion of the valve closer to the surface of the well when installed, is identified at 11, whereas the bottom or lower portion of the valve, i.e., the portion of the valve closer to the bottom of the well when installed, is identified at 12. Those skilled in the art will appreciate how such valves are inserted, retrieved, and operate in a well.

[0012] FIG. 3 illustrates a cross-section of an exemplary, prior art gas lift valve 10. As those skilled in the art will appreciate, such valves include (among other components) gas chamber 15, gas injection valve core 20, and tail plug 25. The gas lift valve is “charged” to a predetermined pressure level by injecting a gas into gas chamber 15 via gas injection valve core 20, i.e., when tail plug 25 is removed from gas lift valve 10, thereby providing a gas charging system access to gas injection valve core 20.

[0013] As described above, although it is desirable and important that gas chamber 15 remain charged to its predetermined pressure level, such prior art gas lift valves can suffer from leakage of gas / pressure from chamber 15, principally on a path past gas injection valve core 20 and tail plug 25 and on to the ambient outside gas lift valve 10. This gas / pressure leakage can occur despite efforts to design gas injection valve core 20 and tail plug 25 to prevent such leakage. Reasons for the leakage can vary, including operators not properly torquing tail plug 25 in place.

[0014] As shown in more detail in FIG. 3 and in FIG. 4 (which is an enlarged version of detail A in FIG. 3), prior art gas lift valve 10 includes gas injection valve core 20 mounted in the body of gas lift valve 10. Since these valve cores are known to be a potential source of leakage from gas chamber 15, tail plug 25 is used to further prevent such leakage as well as protect valve core 20. As shown and described for the prior art device shown in FIGS. 3 and 4, tail plug 25 is inserted into the bore of the gas valve using a straight thread on the lower end of tail plug 25. This further serves to inhibit leakage from gas chamber 15 to the ambient. To prevent leakage of gas even further (across the interface between tail plug 25 and the bore of gas valve 10), O-ring seal 30 and crush washer 35 are deployed, as best shown in FIG. 4. As those skilled in the art appreciate, the O-ring seeks to create an airtight boundary across which it is difficult for gases / liquids to pass, whereas the crush washer seeks to serve the same purpose by its deformations filling leak spots / paths when the tail plug is installed and tightened into place to a degree that the washer crushes between the tail plug and body of valve 10.

[0015] Despite these efforts, it has been observed that gas / pressure still can leak from gas chamber 15 through and / or around gas injection valve core 20 and across the interface between the bore in gas lift valve 10 and tail plug 25 to the ambient outside the gas lift valve. Again, reasons for these leaks can vary, including the failure of operators to properly torque tail plug 25 into gas lift valve 10, inconsistencies in the manufactured thicknesses of crush washer 35, the placement of O-ring 30 too close to an open surface of gas lift valve 10 (where it can literally extrude from the gas lift valve due to extreme pressures), etc. Whatever the reason, the present inventor has discovered a new and improved tail plug and assembly for gas lift valves that better prevents the heretofore described leaks and other problems associated with such valves.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following disclosure may be understood by reference to the description herein taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements. The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate one or more exemplary embodiments of the present invention, except where the drawings are indicated to illustrate the prior art. The present invention should not be considered limited to the following drawings. In the drawings:

[0017] FIG. 1 is a perspective view of an exemplary gas lift valve;

[0018] FIG. 2 is another perspective view of the gas lift valve shown in FIG. 1;

[0019] FIG. 3 is a cross-section of an exemplary, prior art gas lift valve;

[0020] FIG. 4 is an enlarged version of detail A in FIG. 3;

[0021] FIG. 5 is a cross-section of an exemplary gas lift valve of one embodiment of the present invention;

[0022] FIG. 6 is an enlarged version of detail B in FIG. 5;

[0023] FIG. 7 is a perspective view of the tail plug shown in FIG. 5 and FIG. 6;

[0024] FIG. 8 is another perspective view of the tail plug shown in FIG. 7;

[0025] FIG. 9 is a side view of the tail plug shown in FIG. 7;

[0026] FIG. 10 is a top view of the tail plug shown in FIG. 7;

[0027] FIG. 11 is a bottom view of the tail plug shown in FIG. 7;

[0028] FIG. 12 is a perspective view of the crush ring shown in FIG. 5 and FIG. 6;

[0029] FIG. 13 is a front view of the crush ring shown in FIG. 12; and

[0030] FIG. 14 is a side view of the crush ring shown in FIG. 12.DETAILED DESCRIPTION

[0031] Various features and advantageous details are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the description herein. Descriptions of well-known starting materials, processing techniques, components, and equipment are omitted so as not to unnecessarily obscure the invention. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the invention, are given by way of illustration only, and not by way of limitation. Various substitutions, modifications, additions, and / or rearrangements within the spirit and / or scope of the underlying inventive concept will become apparent to those skilled in the art from this disclosure.

[0032] The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended or implied. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.

[0033] The present exemplary embodiments describe an improved tail plug and assembly for a gas lift valve. Those skilled in the art will appreciate that other embodiments are contemplated. For example, FIG. 5 illustrates a cross-section of an exemplary embodiment of gas lift valve 50 including an embodiment of the present invention. As shown, valve 50 may include (among other components / portions) gas chamber 55 and tail plug 65. (Those skilled in the art will appreciate other standard components of a gas lift valve not shown here.)

[0034] In this embodiment, of which there are others within the scope of the present invention, gas lift valve 50 includes a bore at its top / upper end for receiving tail plug 65. This bore in gas lift valve 50 may be a bore in gas lift valve 50 itself or another component of the gas lift valve, such as a removable dome cap. As those skilled in the art will appreciate, a dome cap can be a removable portion of the gas lift valve, which can be threaded into a bore in the top of the gas lift valve and itself having a bore for receiving a tail plug and perhaps even the gas injection valve core. An example of a dome cap is described in co-pending patent application Ser. No. 18 / 925,487, which is incorporated herein by reference. Thus, the bore for receiving the tail plug can be in the gas lift valve itself or the gas lift valve's dome cap. In other words, a bore in the dome cap is also considered a bore in the gas lift valve itself. While not shown in FIG. 5, those skilled in the art will appreciate that a gas injection valve core is mounted in the bore of the gas lift valve shown in FIG. 5 (or perhaps in the bore of the dome cap as described) above gas chamber 55 as discussed above in connection with FIGS. 3-4. As with the prior art gas lift valves, gas lift valve 50 can be “charged” to a predetermined pressure level by injecting a gas into gas chamber 55 via the gas injection valve core.

[0035] As shown in more detail in FIG. 6 (which is an enlarged version of detail B in FIG. 5), tail plug 65 (which may be made of brass in one embodiment or another material in other embodiments) is inserted into the upper bore of gas lift valve 50 (using an NPT thread in one embodiment or a straight thread in other embodiments). As shown (see also FIGS. 7-9), the threads on tail plug 65 that hold it in the gas lift valve are located on the upper portion of the tail plug, as opposed to the lower portion of the prior art tail plug shown in FIGS. 3-4. Likewise, the mating threads in gas lift valve 50 are located on the upper portion of the valve's bore, as opposed to below the upper portion of the bore in the prior art valve as shown in FIG. 4. As those skilled in the art appreciate, a straight thread has a uniform diameter along its length, meaning it remains the same size from one end to the other, typically used for non-tapered applications. In contrast, an NPT (National Pipe Tapered) thread features a tapered design, which means the diameter gradually decreases along the length of the thread. This tapering allows for a tighter seal when connecting pipes, making NPT threads ideal for plumbing and fluid transfer applications, where preventing leaks is essential.

[0036] Applicant has discovered (among other things disclosed here and as will be appreciated by those skilled in the art by reading the present application) that an embodiment using an NPT thread to connect a brass tail plug to a stainless-steel bore in the gas lift valve (or dome cap as the case may be) creates a better barrier against leaks of the type described above in the prior art. Aside from the enhanced leak-proof barrier provided by the NPT thread itself, this enhanced barrier appears to be particularly efficient at eliminating leaks in embodiments where the brass tail plug includes male threads and the stainless-steel bore / dome cap includes female threads since the softer brass tail plug's male threads crush and deform into the bore / dome cap's harder stainless-steel female threads. Applicant has discovered that the leak-proof nature of this design is not as susceptible to operators not properly torquing the tail plug into the bore / dome cap as was the case in the prior art. Note, however, that the present invention is not limited to using a brass tail plug, a stainless-steel bore / dome cap, and / or straight or NPT threads.

[0037] In still other / alternate embodiments, the leak path may be further enhanced against leaks by including crush washer 70 and / or O-ring seal 75 in the path as shown in the exemplary embodiment of FIGS. 5 and 6. In that regard, as shown in FIGS. 5-9, an embodiment of tail plug 65 may have crush washer groove 71, which can be a portion of tail plug 65 having a reduced diameter relative to other diameters of the tail plug, thereby forming a shoulder on the tail plug that mates with a corresponding shoulder in the bore of gas lift valve 50. Likewise, as shown in FIGS. 5-9, tail plug 65 can have an O-ring seal groove 76, which can be a portion of tail plug 65 having a reduced diameter relative to other diameters of the tail plug, thereby forming a groove to hold O-ring seal 75.

[0038] Notably, in one embodiment, the order of crush washer 70 and O-ring seal 75 as arranged on tail plug 65 is reversed with respect to that of the prior art (compare FIGS. 3- 4 toFIGS. 5-6), which applicant also has discovered enhances the leak-proof nature of the tail plug. In other words, in the embodiment of FIGS. 5-6 (as opposed to the prior art embodiments shown in FIGS. 3-4) the crush washer is placed closer to the top / upper end of the tail plug than the O-ring. This further precludes the prior art problem (described above) of the O-ring extruding through the interface between the tail plug and the gas lift valve in extreme pressure conditions.

[0039] FIGS. 7 and 8 are perspective views of tail plug 65 (from FIGS. 5 and 6), whereas FIG. 9 is a side view thereof, FIG. 10 is a top view thereof, and FIG. 11 is a bottom view thereof. Collectively, FIGS. 7-11 illustrate an exemplary embodiment of tail plug 65. For example, FIGS. 7-9 show O-ring seal groove 76 for housing O-ring 75, crush washer groove 71 for housing crush washer 70, and the male portion of threads 85 that interface with the corresponding female threads in the bore of the gas lift valve (or dome cap as the case may be), as best shown in FIG. 6. For embodiments not including crush washer 70 and / or O-ring seal 75, FIGS. 7-9 could be modified to not include regions for housing one or both of those components. FIG. 10 shows that this particular embodiment of tail plug 65 includes a hexagonal head suitable for interfacing with a standard wrench to insert and remove the tail plug from the gas lift valve.

[0040] Finally, FIG. 12 is a perspective view of crush ring 70 shown in FIG. 5 and FIG. 6; FIG. 13 is a front view thereof; and FIG. 14 is a side view thereof. In an embodiment, this crush ring can be made from copper.

[0041] Although the invention(s) is / are described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention(s), as set forth in the claims below. Accordingly, the specification and Figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention(s). Any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature or element of any or all the claims.

[0042] Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The terms “coupled” or “operably coupled” are defined as connected, although not necessarily directly, and not necessarily mechanically. The terms “a” and “an” are defined as one or more unless stated otherwise. The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a system, device, or apparatus that “comprises,”“has,”“includes” or “contains” one or more elements possesses those one or more elements but is not limited to possessing only those one or more elements. Similarly, a method or process that “comprises,”“has,”“includes” or “contains” one or more operations possesses those one or more operations but is not limited to possessing only those one or more operations.

[0043] Accordingly, the protection sought herein is as set forth in the claims below.

Claims

1. A gas lift valve, comprising:a gas chamber;a bore including a first end in fluid communication with the gas chamber and a second end in fluid communication with an ambient atmosphere outside the gas lift valve; anda removable tail plug for sealing at least a portion of the bore, wherein the tail plug is removable via a threaded connection with the bore, and wherein the threaded connection comprises a first set of threads on an upper end of the tail plug and a corresponding second set of threads on an upper end of the gas lift valve.

2. The gas lift valve of claim 1 wherein the tail plug seals at least a portion of the bore to substantially prevent a gas in the gas chamber from leaking through the bore to the ambient atmosphere outside the gas lift valve.

3. The gas lift valve of claim 2 wherein the removable tail plug includes an O-ring groove.

4. The gas lift valve of claim 3 wherein the O-ring groove is located below the first set of threads.

5. The gas lift valve of claim 4 wherein the removable tail plug includes an O-ring in the O-ring groove, and wherein the O-ring assists in substantially preventing a gas in the gas chamber from leaking through the bore to the ambient atmosphere outside the gas lift valve.

6. The gas lift valve of claim 5 wherein the removable tail plug includes a crush washer groove.

7. The gas lift valve of claim 6 wherein the crush washer groove is located below the first set of threads.

8. The gas lift valve of claim 7 wherein the removable tail plug includes a crush washer in the crush washer groove, and wherein the crush washer assists in substantially preventing a gas in the gas chamber from leaking through the bore to the ambient atmosphere outside the gas lift valve.

9. The gas lift valve of claim 8 wherein the O-ring grove is located below the crush washer groove.

10. The gas lift valve of claim 9 including a gas injection valve core mounted in the bore.

11. The gas lift valve of claim 10 wherein the gas injection valve core is mounted in the bore between the gas chamber and the tail plug.

12. The gas lift valve of claim 11 wherein the first set of threads are male threads.

13. The gas lift valve of claim 12 wherein the second set of threads are female threads.

14. The gas lift valve of claim 13 wherein the threaded connection is an NPT connection.

15. The gas lift valve of claim 14 wherein the threaded connection is a brass to stainless steel connection.

16. The gas lift valve of claim 15 wherein the bore is a bore in a dome cap.

17. The gas lift valve of claim 16 wherein the dome cap is detachable from the gas lift valve.

18. The gas lift valve of claim 11 wherein the crush washer is made from copper.

19. The gas lift valve of claim 18 wherein the tail plug includes a head located above the first set of threads.

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