BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to devices and methods for operating a valve in an incremental fashion.
2. Description of the Related Art
Sliding sleeve valves are often used in a hydrocarbon production string to selectively control the flow of production fluid into the production string. A sliding sleeve valve typically includes an outer cylindrical housing that defines a flowbore and a sleeve member that is moveably disposed within the housing. Both the housing and the sleeve member include openings. When the openings are aligned, fluid can be communicated through the openings and into the flowbore.
SUMMARY OF THE INVENTION
The invention provides systems for operating one or more sliding sleeve valves in an incremental, step-type fashion between open and closed positions. This permits the valve or valves to be choked to progressively smaller flow areas. The systems of the present invention also permit the valve or valves to be fully closed without having to progress through incremental steps.
In a preferred embodiment, a sliding sleeve valve is interconnected with hydraulic open and close lines so that fluid flow through the hydraulic lines will actuate the sleeve valve between open and closed positions. In preferred embodiments, the close line incorporates a fluid metering assembly which is operable to flow discrete increments of hydraulic fluid into or out of the sleeve valve. The fluid metering assembly preferably includes a bi-directional check valve assembly and an incremental piston assembly.
During exemplary operation of the system, the sliding sleeve valve is incrementally choked from a fully open position to a partially open position by flowing hydraulic fluid into the close line at a pressure that is below a predetermined level. The incremental piston assembly will be operated to transmit a predetermined discrete amount of fluid to the sleeve valve, thereby moving the sleeve member incrementally toward a closed position.
In the event that it is desired to fully close the sliding sleeve valve, fluid is flowed into the close line at a pressure that is above the predetermined level. The pressurized fluid will open a check valve within the check valve assembly and permit fluid to pass in an unrestricted manner through the fluid metering assembly. The sleeve valve will then be shifted to a fully closed position.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and further aspects of the invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein:
FIG. 1 is a side, cross-sectional view of an exemplary wellbore containing a production tubing string which incorporates sliding sleeve valves and a control system in accordance with the present invention.
FIG. 2 is a schematic side view of an exemplary sliding sleeve valve in a fully open position and an operably associated hydraulic metering assembly, in accordance with the present invention.
FIG. 3 is a schematic side view of the sleeve valve shown in FIG. 2, now having been moved to a partially choked open position.
FIG. 4 is a schematic side view of the sleeve valve shown in FIGS. 2 and 3, now having been moved to a further partially choked open position.
FIG. 5 is a schematic side view of the sleeve valve shown in FIGS. 2-4 now in a fully closed position.
FIG. 6 is a side, cross-sectional view of an exemplary bi-directional check valve assembly used in the hydraulic metering assembly of the present invention
FIG. 7 is a side, cross-sectional view of an exemplary incremental piston assembly used in the hydraulic metering assembly of the present invention.
FIG. 8 is a side, cross-sectional view of the incremental piston assembly shown in FIG. 7, now having been actuated.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates an exemplary wellbore 10 that that has been drilled from the surface 12 through the earth 14. The wellbore 10 passes through production formations 16, 18 and 20, which are separated from one another by substantially impermeable layers 22. The wellbore 10 has been lined with metallic casing 24, in a manner known in the art, and perforations 26 extend through the casing 24 and into the formations 16, 18, 20.
A hydrocarbon production string 28 is disposed within the wellbore 10. An annulus 30 is defined between the outer radial surface of the production string 28 and the casing 24. The production string 28 may be made up of sections of standard production tubing or, alternatively, be formed of coiled tubing, in a manner known in the art. The production string defines an interior flowbore 32 by which production fluids may be conveyed to the surface 12. The production string 28 includes production nipples 34, 36, 38 which are located proximate each of the production zones 16, 18, 20, respectively.
Although three production zones and three production nipples are depicted in FIG. 1, it should be understood that this is for purposes of illustration only, and that there may be more or fewer than three such nipples, as needed or desired. Each of the production nipples 34, 36, 38 is a sliding sleeve valve which can be opened or closed to selectively permit production fluid entering the wellbore annulus 30 from the perforations 26 to enter the central flowbore 32.
A common hydraulic “open” line 40 extends from a surface-based pump, or open side fluid source, 42 and is interconnected with each of the production nipples 34, 36, 38 in a manner which will be described in further detail shortly. In addition, a separate hydraulic “close” line extends from a surface pump, or close side fluid source, 44 to each of the production nipples 34, 36, 38. Close line 46 extends from the pump 44 to production nipple 34. Hydraulic close line 48 extends from the pump 44 to the second production nipple 36, and hydraulic close line 50 extends from the pump 44 to the third production nipple 38. A hydraulic metering assembly 52 is integrated into each of the close lines 46, 48, 50. It is noted that, while the open side fluid source 42 and closed side fluid source 44 are depicted schematically as separate fluid sources, they may, in fact be a single pump or other fluid source.
FIG. 2 illustrates an exemplary sliding sleeve valve 54 of the type used for each of the production nipples 34, 36, 38. The sliding sleeve valve 54 includes an outer cylindrical housing 56 that defines a central flowbore 58. The housing 56 has threaded axial ends 60 to permit the housing 56 to be integrated into the production tubing string 28. Multiple lateral flow ports 62 are disposed through the housing 56. A generally cylindrical sleeve member 64 is disposed within the central flowbore 58 of the housing 56 and is axially moveable with respect to the housing 56. Lateral fluid openings 66 are disposed through the sleeve member 64.
A radially-enlarged recess 68 is formed in a portion of the flowbore 58 of the housing 56. A flange 70 extends radially outwardly from the sleeve member 64 and into the recess 68 to divide the recess 68 into first and second fluid chambers 72, 74. The fluid chambers 72 and 74 are defined between the inner sleeve member 64 and the recess 68 of the housing 56. Fluid seals 76, of a type known in the art, ensure fluid tightness for the chambers 72, 74. One of the hydraulic fluid “close” lines 46, 48 or 50 is interconnected with the first chamber 72. The hydraulic fluid “open” line 40 is interconnected with the second chamber 74.
The fluid metering assemblies 52 each include a bi-directional check valve assembly 78 and an incremental piston assembly 80 which are incorporated into the close line 46, 48 or 50 in a parallel fashion by the use of fluid line splitters 82. The check valve assembly 78 is shown in greater detail in FIG. 6 and includes a housing 84 with a fluid inlet 86 and a fluid outlet 88. Parallel first and second flow paths 90, 92 extend from the fluid inlet 86 to the fluid outlet 88. A first check valve 94 is located within the first flow path 90 and is oriented so as to block fluid flow from the inlet 86 toward the outlet 88 but selectively permit fluid flow along the flow path 90 from the outlet 88 toward the inlet 86. In the depicted embodiment, the first check valve 94 includes a closure member 96 that is biased by compression spring 98 against a valve seat 100. The spring 98 provides a bias force upon the closure member 96 that can be overcome by a first, relatively low, level of pressure by fluid flowing along the first flow path 90 toward inlet 86. As a non-limiting example, a fluid pressure of 100-200 psi would unseat the closure member 96 from the valve seat 100 and allow fluid to pass through the first flow path 90.
A second check valve 102 is located within the second flow path 92. The second check valve 102 blocks fluid flow from the outlet 88 toward the inlet 86, but it will selectively permit fluid flow from the inlet 86 toward the outlet 88. In the depicted embodiment, the second check valve 102 includes a closure member 104 that is biased by a compression spring 106 against a valve seat 108. The spring provides a bias force upon the closure member 104 that can be overcome by a second level of pressure by fluid flowing along the second flow path 92 toward the outlet 88. The second level of pressure is greater than the first level of pressure. As a non-limiting example, a fluid pressure of about 5000 psi would unseat the closure member 104 from the valve seat 108 and allow fluid to pass through the second flow path 92.
Referring now to FIGS. 7 and 8, the incremental piston assembly 80 is shown apart from the other components of the fluid metering assembly 52. The incremental piston assembly 80 includes a tubular piston housing 110 with upper and lower end subs 112, 114 secured at opposite axial ends. Fluid passages 116 are disposed axially through each of the end subs 112, 114. An incremental piston chamber 118 is defined within the piston housing 110 between the end subs 112, 114. End sub 112 provides a fluid inlet for the chamber 118 while end sub 114 provides a fluid outlet. The piston chamber 118 contains an incremental piston pump, generally shown at 120. The incremental piston pump 120 is useful for sequentially displacing a predetermined, known amount of fluid through the piston chamber 118 of the incremental piston assembly 80 and includes a piston sleeve 122 which radially surrounds a piston member 124. The exemplary piston member 124 features an enlarged pressure-receiving end 126, a reduced-diameter shaft portion 128, and an enlarged piston head 130. It is noted, however, that the piston member 124 could have other geometrical designs. The piston member 124 is moveable with respect to the sleeve 122 between a retracted position (FIG. 7) and an extended position (FIG. 8). When moved to the extended position, the enlarged piston head 130 of the piston member 124 displaces a volume of fluid through the fluid outlet 116 of end sub 114 and substantially the same volume of fluid is drawn into the fluid inlet of end sub 112 from the close line 46, 48 or 50. The enlarged piston head 130 of the piston member 124 contacts an end portion 132 of compression spring member 134, which is disposed within the chamber 88. The spring 134 biases the piston member 124 toward the retracted position. Although the spring illustrated in the drawings is a spiral-type compression spring, those of skill in the art will understand that other compressible spring designs could be used, including, for example, Belleville washers or fluid springs, as are known in the art. When fluid pressure is increased within the close line 46, 48, or 50, it bears upon the pressure-receiving end portion 126 to urge the piston member 124 to move axially with respect to the sleeve 122 toward the extended position, and the spring member 134 is compressed by the piston head 130. It is noted that, while the pressure-receiving end 126 of the piston member 124 may be disposed within the surrounding sleeve 122 with a relatively close fit, there are preferably no elastomeric or other fluid-tight seals located between the piston member 124 and the sleeve 122. As a result, it is contemplated that some fluid pressure will seep between the piston member 124 and sleeve 122 during operation.
In operation, the fluid metering assemblies 52 are used to operate each of the production nipples 34, 36, 38 by increments between an extreme open position (i.e., the fully open position depicted in FIG. 2) and an extreme, or fully closed position (see FIG. 5). In other words, the fluid metering assemblies 52 will operate the production nipples 34, 36, 38 between fully open, fully closed and partially open, or “choked” positions. It is noted that, in FIGS. 2-5, the valve is shown in a fully open position (i.e., the fluid openings 66 of the sleeve member 64 are fully aligned with the ports 62 of the housing 56) when the sleeve member 64 is in a raised or upper position within the housing 56, and is closed by moving the sleeve member 64 downwardly with respect to the housing 56, the valve 54 may be constructed so that the valve is fully opened when the sleeve member 64 is in a lower position with respect to the housing 56 and is shifted upwardly or even rotated with respect to the housing for choking and closure to occur. In an exemplary method of operation, the production string 28 is run into the wellbore 10 and typically secured in place with sets of packers (not shown) of a type known in the art. At this point, the production nipples 34, 36, 38 may all be fully opened by pressurizing the common open line 40 with surface-based pump, or open side fluid source, 42. This will flow pressurized fluid into the second fluid chamber 74 of each of the production nipples 34, 36, 38 and urge the flange 70 and sleeve 64 of each upwardly until each of the production nipples 34, 36, 38 are in the fully open position shown in FIG. 2. It is noted that, as fluid enters the second chamber 74 and urges the sleeve 64 upwardly, the first chamber 72 will be reduced in volume, and fluid within the first chamber 72 will exit the first chamber 72 via the respective close lines 46, 48 or 50. The fluid displaced from the first chamber 72 will flow through the bi-directional check valve assembly 78. In order to pass through the check valve assembly 78, the displaced fluid will urge closure member 96 off of its valve seat 100, permitting the fluid to pass through the first flow path 90 of the check valve assembly 78.
When it is desired to choke the production flow into the production nipples 34, 36, 38, the hydraulic metering assemblies 52 may be actuated to sequentially move their respective production nipples to choked position of smaller flow area, as illustrated in FIGS. 3 and 4 and, eventually, the fully closed position depicted in FIG. 5. It is noted that due to the use of separate and independent close lines 46, 48, 50 for each individual production nipple 34, 36 and 38, each production nipple may be choked separately and to a different degree than the other production nipples. To choke the production nipple, fluid is flowed by pump 44 into the respective close line 46, 48 or 50 at a pressure that is below a predetermined level. The predetermined level is the level of fluid pressure that would lo unseat the closure member 104 from its valve seat 108 in the bi-directional check valve assembly 78. The fluid flow into the close line will cause the incremental piston assembly 80 to displace a predetermined amount of fluid, as described previously, into the first chamber 72 of the respective production nipple 34, 36 or 38. The predetermined amount of fluid entering the first chamber 72, will act upon the flange 70 and urge the sleeve member 64 axially downwardly with respect to the surrounding housing 56. From the fully opened position shown in FIG. 2, the sleeve valve 54 will be moved to the partially choked position shown in FIG. 3. The fluid openings 66 will be less aligned with the fluid ports 62 of the housing 56, thereby reducing the amount of available fluid flow area and choking the production nipple 34, 36 or 38.
Once the sleeve member 64 has been moved axially downwardly in an incremental manner, as described, fluid pressure within the close line 46, 48 or 50 is reduced or bled off to permit the compression spring 134 of the incremental piston assembly 80 to return the piston 124 to its retracted position. The compression spring 134 will urge the piston member 124 back to its retracted position. Fluid will pass around the piston portion 126 to refill the piston chamber 118 with fluid. Following the reduction in pressure, the close line 46, 48 or 50 can be repressurized as described above to move the sleeve member 64 a further incremental distance axially downwardly with respect to its surrounding housing 56. From the partially choked position shown in FIG. 3, the sleeve valve 54 will be moved incrementally to an even more choked position, depicted in FIG. 4. The pressure within one or more of the close line(s) 46, 48, 50 can then again be bled off, and pressure reapplied to move the sleeve member(s) 64 of the respective production nipple(s) 34, 36, 38 further downwardly with respect to the surrounding housing 56, thereby further choking the flow area provided by those production nipple(s) 34, 36, 38.
The hydraulic metering assemblies 52 also may be actuated to move an associated production nipple 34, 36 or 38 to the fully closed position shown in FIG. 5 in a single step from either a fully opened position or a choked position. In order to do this, fluid is flowed by fluid source 44 into the respective close line 46, 48 or 50 at a pressure that is above the predetermined level necessary to unseat the closure member 104 from its valve is seat 108. This permits fluid to pass in an unrestricted manner through the second flow path 92 of the bi-directional check valve assembly 78. The pressurized fluid will enter the first chamber 72 of the production nipples 34, 36, 38, act upon the flange 70 and urge the sleeve member 64 axially downward to the fully closed position depicted in FIG. 5. Thus, by applying a fluid pressure to the close line(s) 46, 48, 50 at a level that is above the predetermined fluid pressure level, the incremental piston assembly 80 can be bypassed.
The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention.
Patent Application
20100051289
