Patent Application
20070215358
The invention generally relates to a gas lift valve assembly.
For purposes of communicating well fluid to a surface of a well, the well may include a production tubing. More specifically, the production tubing typically extends downhole into a wellbore of the well for purposes of communicating well fluid from one or more subterranean formations through a central passageway of the production tubing to the well's surface. Due to its weight, the column of well fluid that is present in the production tubing may suppress the rate at which the well fluid is produced from the formation. More specifically, the column of well fluid inside the production tubing exerts a hydrostatic pressure that increases with well depth. Thus, near a particular producing formation, the hydrostatic pressure may be significant enough to substantially slow down the rate at which the well fluid is produced from the formation.
For purposes of reducing the hydrostatic pressure and thus, enhancing the rate at which fluid is produced, an artificial-lift technique may be employed. One such technique involves injecting gas into the production tubing to displace some of the well fluid in the tubing with lighter gas. The displacement of the well fluid with the lighter gas reduces the hydrostatic pressure inside the production tubing and allows reservoir fluids to enter the wellbore at a higher flow rate. The gas to be injected into the production tubing typically is conveyed downhole via the annulus (the annular space surrounding the production tubing) and enters the production tubing through one or more gas lift valves.
As an example,
The gas lift valve 18 typically contains a check valve element that opens to allow fluid flow from the annulus into the production tubing and closes when the fluid would otherwise flow in the opposite direction. For example, the production tubing 14 may be pressurized for purposes of setting a packer, actuating a tool, performing a pressure test, etc. Thus, when the pressure in the production tubing 14 exceeds the annulus pressure, the valve element is closed to ideally form a seal to prevent any flow from the tubing 14 to the annulus 15. However, it is possible that this seal may leak, and if leakage does occur, well operations that rely on production tubing pressure may not be able to be completed or performed. Thus, an intervention may be needed, which may be costly, especially for a subsea well.
Thus, there exists a continuing need for better ways to prevent a gas lift valve from leaking.
In an embodiment of the invention, an apparatus that is usable with a well includes a gas lift valve and an isolation member. The gas lift valve includes a valve element that is located between an annulus and a passageway of a tubing. The valve element is adapted to selectively open and close to control fluid communication through the valve element. The isolation member is adapted to in a first state, isolate the valve element from at least one of the annulus and the passageway and in a second state, permit fluid communication between the valve element and the annulus or passageway.
In another embodiment of the invention, a system includes a production tubing, a mandrel, a gas lift valve and an isolation member. The production tubing includes a passageway to communicate well fluid and the mandrel includes a first passageway to form part of the passageway of the production tubing and a second passageway that is eccentric to the first passageway. The gas lift valve is disposed in the second passageway of the mandrel. The isolation member is adapted to in a first state, isolate the gas lift valve from at least one of the annulus and the first passageway and in a second state, permit fluid communication between the gas lift valve and the annulus or passageway.
In another embodiment of the invention, a technique that is usable with a well includes providing a gas lift valve that includes a valve element to control communication between an annulus of the well and a tubular passageway of the well in response to a pressure. The technique includes preventing leakage through the gas lift valve before the gas lift valve is to be operated. The prevention includes isolating the valve element from at least one of the annulus and the tubular passageway.
In another embodiment of the invention, an apparatus that is usable with a well includes a valve seat, a check valve element, a flow path and a suction passageway. The check valve element is adapted to engage the valve seat to block fluid communication through the valve seat in a first flow direction and retract from the seat to allow fluid communication through the valve seat in a second direction. The flow path communicates fluid flowing in the second direction in response to the retraction of the check valve element. The suction passageway is in communication with the flow path to exert a retraction force on the check valve element in response to the fluid being communicated through the flow path.
In yet another embodiment of the invention, a technique that is usable with a well includes establishing a suction flow path to exert a retraction force on a valve element of a valve to aid in opening the valve element in response to a flow through the valve.
Advantages and other features of the invention will become apparent from the following drawing, description and claims.
Referring to
As a more specific example,
In general, the gas lift valve 50 is configured to control communication between the longitudinal passageway 35 and the annulus of the well. In this regard, the gas lift valve 50 includes upper 60 and lower 61 seals (o-ring seals, v-ring seals or a combination of the above, as examples) that circumscribe the outer surface housing of the gas lift valve 50 for purposes of forming a sealed region that contains the radial ports 58 of the gas lift valve 50 and the radial ports 38. One or more lower ports 52 (located near a lower end 33 of the longitudinal passageway 32) of the gas lift valve 50 are located below the lower seal 61 and are in fluid communication with the radial ports 36 near the lower end 33, the longitudinal passageway 32 is sealed off (not shown) to complete a pocket to receive the gas lift valve 50. Due to this arrangement, the gas lift valve 50 is positioned to control communication between the radial ports 36 (i.e., the central passageway of the production tubing string) and the radial ports 38 (i.e., the annulus). As discussed above, initially, operation of the gas lift valve 50 is disabled. When operation of the gas lift valve 50 is enabled by breaching the isolation member (as described further below), the gas lift valve 50 establishes a one way communication path from the annulus to the central passageway of the production tubing. Thus, when enabled, the gas lift valve 50 permits flow from the annulus to the production tubing and ideally prevents flow in the opposite direction.
Among the other features of the gas lift valve assembly 30, in accordance with some embodiments of the invention, the assembly 30 may be installed and/or removed by a wireline operation in the well. Thus, in accordance with some embodiments of the invention, the gas lift valve assembly 30 may include a latch 59 (located near an upper end 34 of the mandrel 31) that may be engaged with a wireline tool (not shown) for purposes of installing the gas lift valve 50 in the mandrel 31 or removing the valve 50 from the mandrel 31.
The gas lift valve assembly 30 may be used in a subterranean well or in a subsea well, depending on the particular embodiment of the invention.
In accordance with some embodiments of the invention, the gas lift valve 50 may have a general design that is depicted in
The housing 70 includes an interior space 73 for purposes of receiving well fluid that flows in from the radial ports 58. Well fluid that enters the radial ports 58 flows into the interior space 73 and through a venturi orifice 82 of a venturi housing 76, which may be connected to the lower end of the housing 70, for example. The venturi housing 76 is generally concentric with respect to the housing 70, and the venturi orifice 82 minimizes turbulence in the flow of gas from the well annulus to the central passageway of the production tubing.
In other embodiments of the invention, the venturi orifice 82 may be replaced with another port, such as a square edge orifice, for example. Thus, many variations are possible and are within the scope of the appended claims.
As depicted in
Referring to
In accordance with some embodiments of the invention, the check valve assembly 92 is a spring-loaded assembly (due to a spring 100), which controls when a dome-shaped portion as of a valve element 94 (of the assembly 92) allows or closes off fluid communication through the valve seat 98. More particularly, the check valve assembly 92 exerts an upward bias force on the valve element 94 for purposes of biasing the valve element 94 to close off fluid communication through the valve seat 98. The valve element 94 is generally tapered leading away from the dome-shaped portion 95 so that the portion 95 is forced into the valve seat 98 should the production tubing pressure become greater than the annulus pressure. When, however, the annulus pressure is sufficient (relative to the production tubing pressure) to exert a force on the valve element 94 to overcome the spring bias, the valve element 94 retracts to permit fluid to flow from the annulus into the production tubing.
As depicted in
Ideally, fluid cannot flow from the production tubing side of the check valve assembly 92 to the annulus side. However, because leaks may occur, the gas lift valve 50, in accordance with some embodiments of the invention, includes a rupture disk assembly 130. As depicted in
When it is time to use the gas lift valve 50, pressure in the production tubing passageway is increased to a pressure threshold that exceeds the rating of the rupture disk 134 and is significantly above any pressure differential that may develop across the disk 134 during other prior production tubing pressurization operations. In other words, when the pressure in the central passageway of the production tubing overcomes the rating of the rupture disk 134, the disk 134 ruptures, or is breached, to open communication between the central passageway of the production tubing and the check valve assembly 92. Once this occurs, the check valve assembly 92 is enabled to control flow through the gas lift valve 50 so that from this point on the valve 50 is operated as if the rupture disk assembly 130 were never present in the valve 50.
Among the other features depicted in
It is noted that the rupture disk assembly 130 may be located in other places in the gas lift valve 50 and more generally, in other places inside the gas lift valve assembly 30, in accordance with other embodiments of the invention. For example, referring to
As another example, in accordance with other embodiments of the invention, a gas lift valve assembly 250, depicted in
As yet another example of a potential placement option for a rupture disk assembly,
Other variations are possible and are with the scope of the appended claims. For example, in accordance with other embodiments of the invention, an isolation member other than a rupture disk, may be used to initially isolate the valve element of the gas lift valve. More specifically, in accordance with other embodiments of the invention, a sleeve valve may be used to initially isolate the valve element of a gas lift valve. In this regard, the sleeve valve may include a sleeve that is, for example, mounted on the exterior of the mandrel 31 to initially cover and close off communication through the radial ports 38. Upon application of sufficient well annulus or production tubing bore pressure, this sleeve is permanently displaced to expose the radial ports 38 and thus, open communication between the well annulus and the valve element of the gas lift valve. Similarly, a valve, such as a sleeve valve, may be used to initially isolate the port(s) 52, the port(s) 36, etc. Thus, many variations are possible and are within the scope of the appended claims.
In accordance with some embodiments of the invention, a suction force is used for purposes of aiding operation of a valve element, such as the check valve element of a gas lift valve, for example. More specifically, referring to
To further illustrate the technique 350,
As depicted in
When a sufficient pressure is exerted by the fluid that enters the opening 503, the pressure forces the valve element 521 downwardly to cause the valve element 521 to retract from the valve seat 520 to open the valve 500. Thus,
The body 515 includes longitudinal passageways 540 that are generally parallel to the longitudinal axis of the valve 500 and may be regularly spaced about the longitudinal axis of the body 515. Each longitudinal passageway 540 extends from a region of the body 515 near the valve seat 520 to a lower outlet 541 where the well fluid exits the valve 500.
In accordance with some embodiments of the invention, the body 515 also includes suction flow paths for purposes of exerting a force on the dome-shaped portion 521 to aid in opening in the valve element 521.
More specifically, referring also to
Due to this arrangement, when the valve element 521 begins to retract and move out of the valve seat 520, a flow is established through the longitudinal passageways 540. This flow, in turn, creates suction in each of the suction flow paths. Thus, the suction is communicated beneath the dome-shaped portion 523 of the valve element 521 to exert a force on the valve element 521 to further retract the element 521. Therefore, the suction flow paths produce an opening force for the check valve assembly 514.
In the preceding description, directional terms, such as “upper,” “lower,” “vertical,” “horizontal,” etc. may have been used for reasons of convenience to describe the gas lift valve and its associated components. However, such orientations are not needed to practice the invention, and thus, other orientations are possible in other embodiments of the invention. For example, the gas lift valve and its associated components, in some embodiments in some embodiments of the invention, may be tilted by approximately 90° in some embodiments or by 180° in other embodiments to the orientations that are depicted in the figures.
While the present invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.
