GAS-LIFT VALVE AND METHOD OF USE

Abstract

A gas-lift valve comprising an elongated vertically orientated tubular body with inlet ports positioned for communication with the inlet ports of a gas-lift valve mandrel, a valve seat and valve port at the upper end of the valve body, a movable gas charged dome positioned within the body below the valve seat, a valve ball assembly attached to the dome, and a collapsible bellows positioned to move the dome and manipulate the valve ball assembly downward onto and off of the valve seat in response to pressure from said inlet ports of the valve body and pressure on the seat and thereby allow injection gas to flow upward through the valve port to exit at the upper end of the valve body. A tubular latch is provided with a removable plug to provide for pressure testing and completion of the well with only one wireline trip.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/822,281, filed May 10, 2013, and the contents of which are hereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The inventions disclosed and taught herein relate generally to gas-lift valves used during both new and existing well completions, and more specifically are related to gas-lift valve assemblies including corrosion-resistant materials and improved flow characteristics within the ball assembly, as well as methods of use and manufacture the same.

2. Description of the Related Art

It is common practice to pump lift gas into the annulus between a production tubing and surrounding well casing and to pump the lift gas subsequently into the production tubing from the annulus via one or more one way gas lift flow control devices in side pockets that are distributed along the length of the production tubing. The lift gas which is injected through the flow control devices into the crude oil (or other fluid) stream in the production conduit reduces the density of the fluid column in the production conduit and enhances the crude oil production rate of the well.

Commercially available gas lift flow control devices typically use one-way check valves which comprise a ball or hemisphere or cone which is pressed against a valve seating ring by a spring. If the lift gas pressure is higher than the pressure of the crude oil stream in the production conduit then this pressure difference exceeds the forces exerted to the ball by the spring so that the spring is compressed and the ball is lifted, or moved away, from the valve seating ring and lift gas is permitted to flow from the gas filled injection conduit into the production conduit. If, however, the pressure of the crude oil stream is higher than the lift gas pressure in the injection conduit, the accumulated forces of the spring and the pressure difference across the gas lift flow control device push the ball or hemisphere against the ring shaped seat, thereby closing the check valve and preventing crude oil, or other fluid, to flow from the production conduit into the injection conduit.

A problem with the known check valves is that the ball or hemisphere and ring-shaped valve seat are exposed to the flux of lift gas, which may contain liquids or sand or other abrasive particles and/or corrosive chemical components, such as hydrogen sulfide and carbon dioxide. The ball or hemisphere and valve seat are therefore subject to mechanical and chemical erosion, which may result in leakage of the valve, so that crude oil or other fluids may flow into the injection conduit from the production conduit, and may block further lift gas injection when the crude oil, or other fluid, level in the injection conduit has reached the location of the gas lift flow control device or flow control devices.

U.S. Pat. No. 5,535,828 describes a surface controlled gas lift valve which is retrievably inserted in a side pocket in the production tubing of an oil well, wherein a frustoconical valve body is mounted on a hydraulically actuated piston which can be actuated from surface to press the valve body against a frustoconical valve seat and to lift the valve body from the valve seat. The valve body and valve seat are exposed to the flux of lift gas and subject to mechanical and chemical erosion.

U.S. Pat. No. 5,004,007 describes manners to provide a surface controlled chemical injection valve, wherein a flapper type valve body and associated ring-shaped valve seat are protected from exposure to the flux of injected chemicals by a protective sleeve that is pushed by hydraulic pressure through the ring-shaped valve seat and which is pushed back by a spring once the hydraulic pressure has decreased below a threshold level, thereby permitting the flapper type valve body to swing against the ring-shaped valve seat. The chemical injection valve is equipped with a flow restriction connected to the valve housing and a piston, which is actuated by the pressure difference across the flow restriction. The piston is arranged in a cylindrical cavity in the valve housing adjacent to the sleeve and is connected to the sleeve. The piston serves to overcome frictional forces between the sleeve and any seals between the sleeve and valve housing and the presence of the piston adjacent to the sleeve makes the valve complex, expensive and prone to failure if contaminants, sand or abrasive particles accumulate in the cylindrical cavity above the piston, and/or if the seals fail.

The complex design of the surface controlled chemical injection valve renders it unsuitable to replace the known wear prone spring actuated ball valves.

Gas Lift is the method of artificial lift that uses an external source of high-pressure gas for supplementing formation gas to lift the well fluids. Gas may be injected continuously or intermittently, depending on the producing characteristics of the well and the arrangement of the gas-lift equipment. Most wells are gas lifted by continuous flow, which can be considered an extension of natural flow by supplementing the formation gas with additional high-pressure gas from an outside source.

Gas is injected continuously into the production conduit at a maximum depth on the basis of the available injection gas pressure. The injection gas mixes with the produced well fluids and decreases the flowing pressure gradient of the mixture from the point of gas injection to the surface. The lower flowing pressure gradient reduces the flowing bottomhole pressure (BHFP) to establish the drawdown required for attaining a designed production rate from the well. If sufficient drawdown in the bottomhole pressure (BHP) is not possible by continuous flow, intermittent gas lift operation may be used.

Gas-lift is typically achieved by distributing an array of gas-lift valves along the production tubing string. Optimum flow rate is achieved by having one single injection point as deep in the production tubing as possible. Typically natural gas is circulated via a compressor to aerate the production fluid.

Gas-lift valves are typically installed by a latch mechanism in a side pocket gas-lift mandrel that is attached to the production tubing string. Tubing and casing pressures cause the gas-lift valve to open and close, thus allowing gas to be injected into the fluid in the production tubing from the annulus to cause the fluid to rise to the surface. Such gas-lift valves inject gas downward into the production tubing.

The early gas lift valves were the conventional type where—by the tubing mandrel that held the gas lift valve and reverse check valve was part of the tubing string. It was necessary to pull the tubing to replace a conventional gas lift valve. Selectively retrievable gas lift valve and mandrel combinations have been developed. They provide a valve mandrel with a pocket, or receiver, within the mandrel from which the retrievable gas lift valve could be removed or installed by simple wireline operations without pulling the tubing.

The primary wireline device for locating the mandrel pocket and selectively removing or installing a gas lift valve is a kick-over tool. The mandrel is called a sidepocket mandrel because the pocket is offset from the centerline of the tubing. Most sidepocket type retrievable valve mandrels have a full-bore ID equal to the tubing ID. These mandrels permit normal wireline operations.

Gas-lift valves utilize a metal bellows and dome attached to a valve stem having a stem tip or ball that moves upward and downward against a valve seat at the opening of a valve port in response to pressure within the metal bellows. A gas charge applied to the bellows provides the downward force, holding the valve tip or ball on the valve seat. The gas charge applied to the bellows is preset as may be desired. A check valve (which is downstream of the stem tip or ball and seat of the valve) is attached to the lower part of the gas-lift valve. The check valve keeps the flow from the tubing from going back into the casing, i.e., the annulus between the casing and the production tubing.

The gas-lift mandrel serves as a communication port between the casing and the tubing. Gas is injected down the casing into the casing-tubing annulus. The injected gas moves from the annulus to the gas-lift valve through communication ports in the gas lift mandrel and inlet ports in the gas lift valve. The injected gas exits the gas-lift valve downward injecting gas against the formation or against the natural flow of the well.

The opening forces on the valve ball of the gas-lift valve are the casing pressure acting on the area of the bellows (less the area of the valve seat) and the tubing pressure acting on the valve seat area. When the combined casing and tubing pressures are sufficient, the valve tip or ball moves upward from the valve seat to open the valve to allow injection gas to flow through valve port then through the check valve in a downward direction from the gas-lift valve toward the formation. Once the valve is open, it remains open until the casing pressure is reduced to the predetermined closing pressure or the tubing pressure or tubing load is reduced.

Gas-lift valves are installed in a gas-lift mandrel with latches such as a BK-2 or BEK-2 latch. These latches are a spring-loaded ring type latch used to secure valves in the gas-lift mandrel. The side pocket mandrels are in a position with the latch no-go and latch lug facing upward and with a kick-over tool locator in the upward position.

Typically, once a production tubing string is installed (landed), it is desirable to test the seal integrity of the whole system or “Completion” assuring there are no leaks in the system. System components being tested include the packers and gas lift mandrels as well as the pressure containing components. During such testing all communication ports between the casing or annulus must be sealed off either by closing the device or installing a “blank” to replace any sort of circulating device.

In referring to the gas lift system and when a side pocket mandrel is installed in the production string, a “dummy valve”, serving as a “blank”, is generally installed in place of the gas lift valve to assure a positive test. Once the whole production tubing assembly has been tested and gas lift operations are needed to lift the well, wireline intervention is required to remove all dummies and gas lift valves are installed. Wireline intervention to change out dummy valves and replace with live gas lift valves, at minimum, will require two wireline trips per mandrel to complete the job.

The inventions disclosed and taught herein are directed to gas-lift valves that have increased life and improved performance characteristics.

BRIEF SUMMARY OF THE INVENTION

The objects described above and other advantages and features of the invention are incorporated in the application as set forth herein, and the associated appendices and drawings, related to systems for gas-lift valve assemblies and methods for their use and manufacture.

In accordance with aspects of the invention there is provided a method of injecting lift gas into a production conduit of an oil well via one or more downhole gas lift flow control devices which each comprise: a tubular valve housing comprising a flow passage having an upstream end which is connected to a lift gas supply conduit and a downstream end which is connected to the interior of the production conduit; a flapper type valve body which is pivotally connected to the valve housing and is arranged in the flow passage such that if the valve body is pivoted in the open position the valve body is oriented substantially parallel to the flow passage and that if the valve body is pivoted in the closed position the valve body is oriented substantially perpendicular to the flow passage and is pressed against a ring shaped valve seat, thereby blocking passage of fluids through the flow passage; a valve protection sleeve which is slidably arranged in the flow passage between a first position wherein the sleeve extends through the ring-shaped valve seat, whilst the valve body is pivoted in the open position thereof, thereby protecting the valve seat and valve body against wear by the flux of lift gas or other fluids and a second position wherein the sleeve extends through the section of the flow passage upstream of the valve seat, whilst the valve body is pivoted in the closed position thereof; and a flow restrictor forming part of the valve protection sleeve, which is dimensioned such that the flux of lift gas or other fluids flowing through the flow restrictor creates a difference in pressure which induces the sleeve to move towards the first position.

The invention also relates to a gas lift flow control device for injecting lift gas or other fluids into a production conduit of an oil well, comprising: a tubular valve housing comprising a flow passage having an upstream end which is configured to be connected to a lift gas supply conduit and a downstream end which is configured to be connected to the interior of the production conduit; a flapper type valve body which is pivotally connected to the valve housing and is arranged in the flow passage such that if the valve body is pivoted in the open position the valve body is oriented substantially parallel to the flow passage and that if the valve body is pivoted in the closed position the valve body is oriented substantially perpendicular to the flow passage and is pressed against a ring shaped valve seat, thereby blocking passage of fluids through the flow passage; a valve protection sleeve which is slidably arranged in the flow passage between a first position wherein the sleeve extends through the ring-shaped valve seat, whilst the valve body is pivoted in the open position thereof, thereby protecting the valve seat and valve body against wear by the flux of lift gas or other fluids and a second position wherein the sleeve extends through the section of the flow passage upstream of the valve seat, whilst the valve body is pivoted in the closed position thereof; and a flow restrictor forming part of the valve protection sleeve, which is dimensioned such that the flux of lift gas or other fluids flowing through the flow restrictor creates a difference in pressure which induces the sleeve to move towards the first position.

In accordance with further aspects of the disclosure, a method and gas-lift valve apparatus is proposed to allow for the injection gas to be injected from the gas-lift valve upward rather than downward. The proposed method and gas-lift valve apparatus may be utilized in conjunction with a production tubing string having a plurality of side pocket mandrels at spaced intervals along the string. Each of the gas-lift valves is operated by available injection pressure or a combination of available injection pressure in conjunction with pressure, within the production tubing at the depth placement of each gas-lift mandrel.

The method proposes and utilizes a gas-lift valve that prevents downward flow of injection gas, i.e., toward the well formation, and provides upward flow of injection gas through a latch located at the top of the valve in the direction of and along with the natural flow of the well. This is accomplished by redirecting the delivery of gas upward through the latch. In other valves the injection gas exits at the bottom of the valve through a check valve. The check valve in the proposed gas-lift valve is incorporated within the main body of the gas lift valve.

When the injection gas is injected in an upward direction along with the natural flow of the well, the formation containing the fluids to be recovered is relieved of downward injection pressure. Testing has shown that reversing the direction of injection gas flow into the production string from downward, as is done with prior gas-lift valves, to upward as described in the proposed gas-lift valve will cause the gas lifted well to act as if it is flowing on its own. The upward injection of gas from the gas-lift valve will eliminate or reduce the eddying effect on the fluids that occurs in the use of conventional gas-lift valves such as injection pressure operated (IPO) and production pressure operated (PPO) gas-lift valves. Testing has shown that one may anticipate as much as a 40% increase in production with the use of the proposed gas-lift valve in conjunction with gas lift design options.

The proposed gas-lift valve is configured with a body, a gas charged dome and bellows within the body to manipulate a valve stem and attached valve ball on and off of a valve seat. When a combination of the casing pressure from the inlet ports of the gas-lift valve and the tubing pressure on the valve seat reaches or exceeds the nitrogen gas charge within the dome and the bellows of the valve, the bellows will collapse moving the dome downward, causing the valve ball to come off of the valve seat to allow gas to flow through the port and upward through the check valve located in the upper portion of the proposed gas-lift valve, continuing upward through the attached latch. The injection gas then exits the gas lift valve assembly through the top of the latch.

Redirecting the injection gas upward along with the natural flow of the well will increase production by adding additional drawdown to the formation. Also injecting gas upward with the natural flow of the well will relieve the formation from injection pressures and stabilizing well flow. Stabilizing the flow of a gas lift well or simulating a natural flowing well, not only increases production but relieves the whole system from stress caused by downward injection. Consequently, the proposed new gas-lift valve and method of gas-lift injection will enhance or increase the production of fluids from the well when compared to gas-lift valves that injection gas downward in a direction counter to the natural flow of the well.

This proposed gas-lift valve and method may be in place of most if not all of the gas-lift valves currently being utilized in the industry. This would include by way of example such valves as the Camco-style IPO (Injection Pressure Operated gas-lift valve), the PPO-style (Production Pressure Operated gas-lift valve), the AT1-BK (Altec Bellows protected Injection Pressure Operated gas-lift valve), and the AT1-CF-BK (Constant Flow Injection Pressure Operated gas-lift valve).

The proposed gas lift valve and method is to be used in conjunction with a new flow through latch design, designated as the “EBEK-FT” latch. This new latch will provide a one-hole down-stream choke to the injection gas. The new latch, configured with a desired sizing of a choke down-stream of the main port of the gas lift valve, will provide a variety of gas lift design options. The latch will allow the designer to use the down-stream choke to size a desired gas passage required to lift the well and in turn size the main port, (ball and seat) of the gas lift valve larger as may be desired. A larger main port (ball and seat) may be desirable as it will allow more tubing effect in acting to open and close the valve.

The proposed gas lift valve and method may also be used in conjunction with the new flow through latch design in combination with a plug. The valve latch and plug combination, designated as the “EBEK-FTD” latch, has all of the benefits as the EBEK-FT latch but will, in addition, provide a removable plug that is installed in the top of the latch. This removable plug may be fitted to the valve and latch combination during the initial completion of the well when it is desired to run gas-lift valves. The plug and latch combination, posing as a dummy valve, will enable testing of the annulus after completion of the well. Once the annulus is tested and the well completed, if gas-lift operations are desired, only one wireline trip will be required to pull the plug from the latch in order to activate the gas-lift valve.

This plug and latch combination will save the consumer from the need to purchase dummy valves and BK-2 latches that would ordinarily have to be replaced with wireline operations when gas lift operations are required in the well. It will also reduce the need for wireline intervention, including the time and risks associated with multiple wireline trips into and out of the well.

These and other features, advantages and embodiments of the gas lift method and flow control device according to the invention are described in more detail in the accompanying claims, abstract and detailed description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following figures form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these figures in combination with the detailed description of specific embodiments presented herein.

FIG. 1 illustrates a cross-section schematic elevation view of a typical prior art gas-lift valve.

FIG. 2 illustrates a cross-section elevation view of the gas-lift valve assembly and latch of Applicant's invention as described herein.

FIG. 3 illustrates a partial cross-sectional view of the valve of FIG. 2 showing the dome and bellows configuration of the valve assembly in FIG. 2.

FIG. 4 illustrates a cross-sectional elevation view of the bellows rod of the value assembly shown in FIG. 2.

FIG. 5 illustrates a cross-sectional view of the latch configuration for use with the valve assembly of FIG. 2.

FIG. 6 illustrates a cross-sectional view of the latch configuration of FIG. 5 with a latch plug in place.

FIG. 7 illustrates a side view of a well having mandrels and installed valves.

FIG. 8 illustrates a cross-section elevation view of the gas-lift valve assembly and latch of Applicant's invention as described herein.

While the inventions disclosed herein are susceptible to various modifications and alternative forms, only a few specific embodiments have been shown by way of example in the drawings and are described in detail below. The figures and detailed descriptions of these specific embodiments are not intended to limit the breadth or scope of the inventive concepts or the appended claims in any manner. Rather, the figures and detailed written descriptions are provided to illustrate the inventive concepts to a person of ordinary skill in the art and to enable such person to make and use the inventive concepts.

DETAILED DESCRIPTION

The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Lastly, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims.

Applicants have created improved retrievable gas-lift assemblies, and methods for their use and manufacture.

Turning now to the figures, FIG. 1 there is shown a cross-section elevation view of a gas-lift valve 10 and latch 11 of the conventional prior art type. The valve to has a metal bellows 12 in communication with a gas charge dome 15 at its top. The dome 15 is stationary and has a constant volume to provide pressure to expand the bellows 12.

The bellows 12 is positioned to manipulate a valve stem 14 positioned below the bellows 12. The valve stem 14 has a stem tip or ball 16 that moves upward and downward below the bellows 12 against a valve seat 18 at an opening to a valve port 20 in response to pressure on the metal bellows 12 from the gas charge dome 15. A predetermined gas charge is applied to the dome 15 and bellows 12 so as to provide a downward force on the valve ball 16 to hold it on the valve seat 18 to close the valve port 20. The valve port 20 is in communication with injection gas ports 17.

A check valve 22 incorporated into the lower part of the gas-lift valve that is positioned downstream from and below the valve ball 16, valve seat 18 and valve port 20. The position of the check valve 22 in these conventional gas-lift valves keeps the flow from the tubing in which the valve is incorporated from going back into the casing (annulus) and maintains outward flow of the injection gas down the tubing through valve port 20 and gas ports 17 toward the well formation and counter to the flow of the fluid in the tubing.

FIG. 2 shows a cross-section elevation view of the gas-lift valve assembly 40 and latch 100 of Applicant's invention in accordance with its position in the well. As can be seen in FIG. 2 and FIG. 3, an enlarged partial cross-section view, the valve assembly 40 is comprised, from top to bottom, of check valve housing 42, valve seat housing 44, bellows housing 46, valve core housing 48, and valve nose cone 50. The check valve housing 42 and the valve core housing 48 are adapted to receive a packing stack assembly, not shown. The gas-lift valve assembly 40 is configured to be oriented vertically in the well with the check valve housing 42 at the top.

A check valve assembly 52 is mounted within the valve check housing 42. The check valve assembly 52 is comprised of a check spring and washer combination 54 that is biased against a vertically orientated lower check valve dart 56. The spring 54 retracts vertically up and down to position the check valve dart 56 against a lower check valve pad 58. The check valve pad 58 defines the opening of a check valve port 60. The extension of the check spring 54 will move the valve dart 56 away from the valve pad 58 to open the check valve port 60. Compression of the check spring 54 will move the valve dart 56 toward the valve pad 58 to close the check valve port 60.

An injection gas seat assembly 62 is mounted within the injection valve seat housing 44. The injection gas seat assembly 62 is comprised of injection gas valve seat 64 having an upper end 63 and a lower end 65. The valve seat 64 defines a vertically extending injection gas port 66.

Extending vertically below the valve seat housing 44 is the bellows housing 46 has inlet ports 49 positioned for communication with the inlet ports of the mandrel. A bellows assembly 70 is mounted with the bellows housing 46 and is positioned at the lower end 65 of the valve seat 64. The bellows assembly 70 is comprised of an injection gas valve ball assembly 68, a bellows adaptor 74 that is removably mounted to the hollow dome 71.

A tubular bellows 72 extends from the base of the dome 71. The lower end of the bellows 72 is mounted on the valve core housing so that the upper will compress and expand in response to external pressures. A bellows rod 78 extends from the dome 71 through the valve core housing and bellows 72 to support and guide the dome 71 as the dome moves in response to movement of the bellows 72.

The bellows adaptor 74 is preferably threadably mounted to the dome 71 so that it may be removed to allow fluid to be inserted through the hollow dome 71 and the bellows rod 78 into the valve core housing 48 so that it will fill the space between the valve core housing and the bellows. Air in the space the space between the valve core housing 48 and the bellows 72 is expelled through a communication port 83 in the bellows rod 78.

The gas valve ball assembly 68 is attached to the bellows adaptor 74 which in turn is attached to the dome 71 at its upper end. The valve ball assembly 68 is configured to move up and down against the lower end 65 of the valve seat 64 as the adaptor 74 moves in response to injection gas pressure acting against the dome 71 and bellows 72 and tubing pressure at the valve port 66.

As shown in FIGS. 2 and 3, the dome 71 has a bore or port 76 adapted to receive the hollow bellows rod 78. This bellows rod 78, shown in FIG. 4, is attached to the dome 71 and is slidably received through the valve core housing 48 that supports the tubular metal bellows 72. In this manner the bellows rod 78 extends between the dome 71 and the valve core housing 48 and through the bellows 72.

As shown in FIG. 4, the hollow bellows rod 78 has a through bore 79 and a cross-hole communication port 83 drilled at its top end which is positioned below the dome 71 and into the bore 79 of the bellows rod 78. Connector area 81 allows for a cold-press connection, or alternatively, a thread connection, to the dome 71.

A gasket 77, which may be made of brass or copper, is provided at the interface of the dome 71 and bellows rod 78. The gasket 77 serves as a seal between the valve core housing 48 and the dome 71 when the bellows 72 is fully collapsed and contracted to provide hydraulic bellows protection.

As shown in FIG. 2, a bore 80 in the valve core housing 48 is configured to slidably receive the hollow bellows rod 78 in response to movement of the bellows 72 and dome 71. A one-way valve stent 85 is provided in the valve core housing 48 at the base of the bore 80 to provide communication with the bore 80 of the valve core housing 48. The one way valve stent 85 provides a means for insertion of gas, preferably Nitrogen, in order to charge the dome 71. The nose cone 50 is attached to the valve core housing 48 at its base to complete the valve assembly 40.

The vertically extending valve core housing 48 provides protection to the bellows 72 as it also serves as a guide for the bellows rod 78 when the bellows rod 78 slides into the bore 80 of the valve core housing 48. This keeps the bellows 72 from twisting or bending out of alignment. This configuration also serves as a stop to limit the total travel of the bellows 72 as well as a means or barrier to trap the fluid behind the bellows 72 when the injection valve is fully open.

FIG. 5 is a cross-sectional view of the proposed flow through latch, designated as the “EBEK-FT” latch, configured for use with the valve assembly 40. The latch 100 is comprised of a hollow latch post 101 having an elongated bore 114 that is inserted within a latch body 102. The latch 100 is provided with a latch spring 103 and a latch ring 104. A stop 105 is provided for attachment of the latch 100 to the upper end of the check valve housing 42 of the gas-lift valve assembly 40. Shear pin 106 and roll pin 107 are also provided. The hollow latch post 101 and bore 114 allows flow from the top of the valve assembly 40 to exit “upward” along with the natural flow of the well.

As shown in FIG. 6, the latch 100 may also be provided with a removable prong or latch plug 110 and incorporated O-ring seals 111. The combination of valve latch 100 and plug 110, designated as the “EBEK-FTD” latch, has all of the benefits as the EBEK-FT latch but will, in addition, provide a removable plug 110 that is installed in the top of the latch. The plug 110 is installed within the latch post 101 and secured by a brass shear pin 112. An O-ring 108 is placed between the latch post 101 and the latch stop 105 and an O-ring 109 is also placed at the connection between the valve assembly 40 and latch 100.

The latch 100 may be provided with a “choke” in the bottom of the latch accomplished by reducing or “choking” the bore 114 at the lower end of the latch post 101 to a desired dimension. The upper portion of the bore 114 of the latch post 101 may be maintained at a constant size such as ⅜″ in diameter. Chokes may be made in a variety of sizes such as ⅛″, 10/64″, 12/64″, 16″64″, or 20/64″ by providing a plurality of corresponding latch posts 101 each having a bore 114 in a size as may be desired for a particular gas-lift design. The designer may determine whether or not to use a latch 100 with a choked latch post or, if so choked, to select from a variety of chokes simply be using a desired latch post 101 having a desired choke dimension of the bore 114. The pressure shear value of the shear pin 112 selected for use will depend upon the choke size of the latch post 101.

An advantage of a choke downstream from the gas valve ball assembly 68 and the gas valve seat 64 of the gas-lift valve assembly 40 in the direction of the flow of the well is that when the valve is fully open the pressure drop across the gas-lift valve will be seen at the choke in bore 114 in the lower end of latch 100 so that the valve seat 64 and ball assembly 68 will be protected from the flow of any fluids including salt water and/or small solids in the fluids that may cut the seat 64 or ball assembly 68 and as a result contribute to leakage of the valve.

Operation of Bellows/Gas Lift Valve

A gas lift design is determined from data generated by the well conditions. This data includes certain well parameters such as the available injection pressure from the compressor, back pressure from the well flow, and temperatures of the formation. This well information is used to determine a Test Rack Opening (TRO) pressure that is used to establish the pressure inside the bellows 72 of the valve assembly 40.

A gas such as Nitrogen is then used to pressurize the bellows 72. When the bellows 72 is pressurized, the bellows 72 extends to move the dome 71 and attached ball assembly 68 upward to position the gas valve ball assembly 68 in contact with the lower end 65 of the valve seat 64. The contact of the gas valve ball assembly 68 with the valve seat 64 will close the valve port 66.

Referring to FIG. 7 the gas lift valve assembly 40 may then be installed in a gas lift mandrel 702 on the surface and run with the production tubing 704 during completion of the well 700. The gas-lift valve assembly 40 may also be installed by means of a wire, utilizing a wireline unit, in a side-pocket mandrel previously installed on the tubing string. It is anticipated that a plurality of gas-lift valve assemblies 40 and gas-lift mandrels 702 will be utilized in a single well, as shown in FIG. 7.

If after installation, the hydrostatic pressures in the tubing string are greater than the pressure (TRO) inside the dome 71 and bellows 72 of a particular gas-lift valve assembly 40, the bellows 72 of that gas-lift valve assembly will collapse. When a bellows 72 collapses due to well conditions, the dome 71 and the attached gas valve ball assembly 68 will move downward to move the gas valve ball assembly 68 away from the lower end 65 of the valve seat 64 to open the valve port 66. This will allow injection gas 706 from the annulus between the casing and production tubing to be injected to into the fluid column of the production tubing string.

When the gas-lift valve is in the closed position in the well, the gas valve ball assembly 68 will be positioned against the valve seat 64. When the valve begins to move to the open position with the gas valve ball assembly 68 moving away from the valve seat 64 due to gas pressures or hydrostatic pressures acting on the outside of the bellows (or outside of the valve itself), the bellows rod 78 moves in a downward direction, thus causing fluid to be pushed up through the hollow bellows rod 78 to exit the bellows rod 78. When the valve is fully opened, the bellows rod 78 continues to slide down in the extending valve core housing 48 until the gasket 77 contacts the valve core housing 48 to provide hydraulic bellows protection.

Use of the gas-lift valve assembly 40 with latch 100 and plug 110 in combination with a gas lift mandrel 702 provides the opportunity to insert the plug 110 into the top of the latch 100 in order to prevent communication between the annulus and the inside of the production tubing 704 which, in essence, will serve the purpose of the dummy valve typically installed for testing purposes. The plug 110 is installed in the latch 100 and secured in place by the shear pin 112. The O-ring seals 111, 108 and 109 serve to block communication between the annulus and tubing.

When the assembly 40 and latch 100 are installed in a side pocket mandrel pose as a dummy valve, all conventional operations requiring the use of a dummy valve may be performed on the well. Only one run with a wireline unit is required when it is deemed necessary for the gas-lift valve assembly 40 to be activated. That run will allow the plug 110 to be pulled from the top of latch 100 in order to activate the gas-lift valve assembly allowing for injection of gas 706 upward with the flow 710 of the well 700 from the top of the latch 100.

The gas-lift valve assembly 40 and latch 100 in combination with the plug 110 and removal procedure provides significant financial benefits to the user. This combination and procedure allows the gas-lift valve to be run on initial completion of the well posing as a dummy valve and thus eliminates the cost of dummy valves and latches on initial completion when live IPO valves will be required and reduces or eliminates wireline cost to pull dummies and run live valves.

The proposed combination and procedure also reduces the problems with wireline operations that may occur during the changing out of dummy valves, for example, dropping dummies or valves or having the wireline of dummy valve get stuck in the tubing which may result in the need for wireline fishing jobs. The combination and procedure also provides the user design versatility for the gas lift operation as certain gas-lift valves may be activated in the string, as desired, depending on the procedure being done at the time.

It is thought that the gas-lift valve and method of the present invention and many of its attendant advantages will be understood from the foregoing description. It is also thought that one may make various changes in the form, construction and arrangement of the parts of the gas-lift valve assembly, apparatus and method without sacrificing its material advantages or departing from the spirit and scope of the invention and that the form described herein is merely an exemplary embodiment of the invention that is limited only by the following claims.

Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of Applicant's invention. For example, and as shown in the FIG. 8, a carbide ball (or similar feature) 90 can replace check spring and washer combination 54 and check valve dart 56 shown in FIG. 2 of the disclosure, such that carbide ball 90 is used in place of the check dart 56, and clover-leaf-shaped orifices 92 are bored in the check valve housing 42 to create flow passages around the carbide ball 90. A carbide ball 90 is free floating within the valve check housing 42. The carbide ball 90 is free to move substantially vertically up and down to position the carbide ball 90 against a lower check valve pad 58 or against the clover-leaf-shaped orifices 92. The check valve pad 58 defines the opening of check valve port 60. The carbide ball 90 is configured to move up and down in response to injection gas pressure acting against check valve port 60. The injection gas pressure acting against the check valve port 60 acting on the carbide ball 90 will move the carbide ball 90 away from the valve pad 58 to open the check valve port 60 and into the clover-lead-shaped orifices 92 to create flow passages around the carbide ball 90. The use of the carbide ball provides more resistance to erosion, while the creation of the shaped bore passages promote flow around the ball, thus increasing the working efficiency of the valve assembly and the overall system. The check spring and washer combination 54 and check valve dart 56 are more likely to erode over time than the carbide ball 90.

As a further example, and as shown in FIG. 8, a ball stem assembly 94 may replace valve ball assembly 68. Ball stem assembly 94 contains a portion of its substantiality round portion truncated to create a substantially flat top, while valve ball assembly 68 had a substantially round top. The ball stem assembly 94 is configured to move up and down against the lower end 65 of the valve seat 64 as the adaptor 74 moves in response to injection gas pressure acting against the dome 71 and bellows 72 and tubing pressure at the valve port 66. The use of ball stem assembly 94 provides better flow over the improved truncated top round portion, thus increasing the working efficiency of the valve assembly and the overall system.

Further, the various methods and embodiments of the methods of manufacture and assembly of the system, as well as location specifications, can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa.

The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.

The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims.

Claims

1. A check valve assembly for controlling fluid flow in retrievable gas-lift valve apparatus, comprising:

a check valve housing, wherein the check valve housing has a vertically extending through-bore;

a substantially spherical body slideably disposed within the vertically extending through-bore of the check valve housing; and

a seat disposed in a lower portion of the vertically extending through-bore and permitting the fluid flow therethrough.

2. The check valve assembly of claim 1, wherein the substantially spherical body is capable of substantially free-floating vertical movement within the check valve housing.

3. The check valve assembly of claim 1, where in the substantially spherical body is a ball.

4. The check valve assembly of claim 1, where in the substantially spherical body is a carbide ball.

5. The check valve assembly of claim 1, wherein the through-bore of the check valve housing comprises clover-leaf-shaped orifices.

6. The check valve assembly of claim 1, wherein the through-bore of the check valve housing comprises clover-leaf-shaped orifices.

7. The check valve assembly of claim 6, wherein the clover-leaf-shaped orifices are located in its upper portion of the through-bore of the check valve housing.

8. The check valve assembly of claim 6, wherein the clover-leaf-shaped orifices are located above the substantially spherical body.

9. A retrievable gas-lift valve apparatus, the apparatus comprising:

an upper portion, comprising: a check valve housing, wherein the check valve housing has a vertically extending through-bore; a substantially spherical body located within the vertically extending through-bore of the check valve housing;

a lower portion comprising: valve seat housing, a bellows housing, and a valve core housing.

10. The retrievable gas-lift valve apparatus of claim 9, wherein the substantially spherical body is a ball.

11. The retrievable gas-lift valve apparatus of claim 9, wherein the substantially spherical body is a carbide ball.

12. The retrievable gas-lift valve apparatus of claim 9, wherein the through-bore of the check valve housing has clover-leaf-shaped orifices.

13. The retrievable gas-lift valve apparatus of claim 9, wherein the wherein the through-bore of the check valve housing has clover-leaf-shaped orifices in its upper portion.

14. The retrievable gas-lift valve apparatus of claim 9, wherein the lower portion comprises a gas valve ball, wherein the gas valve ball comprises an upper substantially round portion, wherein the upper substantially round portion comprises a flat top.

15. A method of injecting a gas into a production conduit of an oil well, the method comprising:

a) installing a gas-lift valve assembly;

b) collapsing a bellows of the gas-lift valve assembly when the hydrostatic pressures in the tubing string are greater than the pressure inside and the bellows;

c) moving a bellows dome of the bellows and a gas valve ball of the gas-lift valve assembly downward and away from a valve seat to open a valve port of a valve assembly of the gas-life assembly;

d) moving a substantially spherical body vertically through a through-bore within a check valve housing of the gas-lift valve assembly; and

d) injecting gas from the gas valve assembly into the fluid column of the production tubing string.

16. The method of claim 15, wherein the substantially spherical body is a ball.

17. The method of claim 15, wherein the substantially spherical body is a carbide ball.

18. The method of claim 15, wherein the through-bore of the check valve housing has clover-leaf-shaped orifices.

19. The method of claim 15, wherein the gas flows through the clover-leaf-shaped orifices.

20. The method of claim 15, wherein the gas valve ball comprises an upper substantially round portion, wherein the upper substantially round portion comprises a flat top.