Plug Tip and Seat for a Gas Lift Valve

FIELD OF THE INVENTION

[0001]The present invention relates to a plug and seat valve trim and, more particularly, to a plug having at least a tip formed from superhard material.

BACKGROUND OF THE INVENTION

[0002]In certain fluid-handling systems, such as mineral extraction systems, a variety of flow control devices are used to control a flow rate, a pressure, and other parameters of fluid flow. For example, in mineral extraction systems, gas lift valves may be utilized to regulate the flow of fluid (e.g., oil, gas, and water) from the annulus to the bore of a well. A bellows, spring, or the like, drives a movable valve member over an opening through which the fluid flows. Shifting the position of the movable valve member relative to the opening allows the flow rate of the fluid through the opening. Movable valve members may be subjected to relative high pressure drop environments, abrasive media entrained in the fluid, and/or fluid flow cavitation, which may lead to wear, erosion, and other degradation.

SUMMARY OF THE INVENTION

[0003]In one aspect, the present invention relates to a valve assembly having components formed from a superhard material.

[0004]In another aspect, the present invention relates to a gas lift incorporating a valve assembly having components formed from a superhard material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1 is an elevational view, in cross-section, of a prior art gas lift valve.

[0006]FIG. 2 is an elevational view, in cross-section, of a gas lift valve including one embodiment of the valve plug and valve seat of the present invention.

[0007]FIG. 3 is an exploded view of the valve of the present invention.

[0008]FIG. 4 is a cross-sectional view of the valve of FIG. 3.

[0009]FIG. 5 is an enlarged view, in cross-section of the valve plug and seat of FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0010]Embodiments of the invention are described more fully hereafter with reference to the accompanying drawings. Elements that are identified using the same or similar reference characters refer to the same or similar elements which perform the same functions across various embodiments. The various embodiments of the invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0011]When introducing elements of various embodiments, the articles “a,” “an,” “the,” “said,” and the like, are intended to mean that there are one or more of the elements. The use of “top,” “bottom,” “above,” “below,” and variations thereof is made for convenience with respect to the orientation depicted in the drawings. Unless otherwise specified, the use of such terms does not require any particular orientation of the actual components. The term “fluid” encompasses liquids, gases, vapors, and combinations thereof. Unless otherwise specified, the term “connected” includes both direct and indirect connections.

[0012]Mineral extraction systems (e.g., drilling systems, hydraulic fracturing systems, etc.), utilize fluid-handling equipment. Turning to FIG. 1, there is shown one example of a prior art fluid-handling system. The system includes a housing H in which is disposed a valve member in the form of ball B. Ball B rests on valve seat S. Ball B is connected by stem ST to a piston P. Ports or openings O in housing H allow for the flow of fluid into housing H. The pressure of the gas on piston P causes piston P to move upward and thus lift ball B off of valve seat S. The gas can then travel down into the opening made by movement of ball B off of valve seat S. As depicted in FIG. 1, valve seat S is formed into the housing H. It will be appreciated that the valve seat may comprise a separate, removable component disposed in the housing and sealed to prevent fluid flow around it. A check valve V allows the fluid to pass downward and out through outlets OL and also prevents the gases from moving back up into the area of the housing in which the ball valve is positioned. As shown in FIG. 1, a spring SP returns the ball B back into position when the gas pressure is sufficiently low enough to be overcome by the biasing force of the spring. It will be appreciated that the valves could be controlled by actuators using varying types of return mechanisms (e.g., spring return, bellows, dual actuation, etc.) In some cases, the ball B and/or the seat S may incur degradation (e.g., erosion) and/or wear as a result of high pressure drops experienced at a tip portion of the plug or ball. Traditional plug and seat valve trims may include a tungsten carbide material, which may be vulnerable to degradation, thereby leading to replacement of the valve after a relatively short duration.

[0013]To protect against the degradation and wear, the present invention incorporates a plug and seat valve trim that includes at least a tip portion having a superhard material. In a preferred embodiment the superhard material comprises a diamond-based material (e.g., silicon centered diamond, polycrystalline diamond, or other material which includes diamond), polycrystalline cubic boron nitride, a material with a hardness value exceeding approximately (meaning within 1-10%) 20 gigaPascals (GPa) based on the Vickers hardness test, and/or a material with a hardness value exceeding approximately (meaning within 1-10%) 4500 Hardness Brinell (HB) on the Brinell scale. Dur to manufacturing tolerances, size limitations, and/or cost constraints, it may be impractical or undesirable to have the entire valve trim formed from a superhard material. Accordingly, the present invention comprises a valve trim in which the tip portion of the plug and/or the seating surface of the seat are formed from a superhard material.

[0014]Turning to FIGS. 2-5 there is shown a plug valve and seat of the present invention disposed in a gas lift assembly shown generally as 10. As best seen in FIGS. 3 and 4, the valve member 12 comprises a tip 14 and a stem 16. Tip 14 includes a base portion 18 and a frustoconical portion 20. It will be appreciated that the exact shape of the tip 14 may vary, provided that the shapes of tip 14 and of the seating surface are sufficiently complementary as to close off fluid flow when the valve member is fully seated. For example, tip 14 may be frustoconical, conical, hemispherical. Stem 16 includes a head 22 and a shaft portion 24. As shown in the drawings, shaft portion 24 is threaded, but it need not be so depending on the valve system in question. Head 22 has a formation 26 which is complementary in shape to base portion 18. As shown in FIGS. 3 and 4, base portion 18 and receiving formation 26 are both cylindrical in shape, however, the exact shape may vary but they are preferably complementary to one another. Base portion 18 fits within receiving formation 26 and is held in place by epoxy adhesive, brazing, thermal contraction, or other means well known to those skilled in the art.

[0015]Also best seen in FIGS. 3 and 4 is one embodiment of the valve seat 30 of the present invention. Valve seat 30 includes ring 32 and body 34. Ring 30 has an opening therethrough which forms seating surface 36. Seating surface 36 is preferably tapered at an angle that is complementary to frustoconical portion 20 of tip 14. Body 34 has an opening 38 therethrough to allow flow of fluids when the valve is in the open position. Body 34 also has receiving formation 40 in which is received ring 32. Ring 32 is held in position within body 34 by epoxy adhesive, brazing, thermal contraction, or other means well known to those skilled in the art. Body 34 may include an annular groove 42 in which is received a seal ring or gasket 44.

[0016]As seen in FIGS. 2 and 5, the valve is installed in a gas lift assembly shown generally as 10. Gas lift assembly 10 includes housing 60, a chamber 62, inlet ports 64, outlet ports 66, and check valve 68. The valve seat 30 is positioned on shoulder 70. The valve assembly of the present invention can thus be retrofit into existing gas lift assemblies. It will be appreciated that the valve seat 30 may also be built into and integrally formed in housing 62 if desired. Valve member 12 is attached to a piston 72 by stem 24. Piston 72 has one or more grooves 71 in which are positioned seal rings/gaskets 73. Piston 72 includes a threaded bore 74 which is sized to receive threaded stem 24. Lock nut 76 prevents stem 24 from backing out of bore 74. It will be appreciated that stem 24 may be attached to piston 72 in other ways well known to those skilled in the art, including being integrally formed therewith. Biasing member 78 exerts a downward force on piston 72. As shown in the drawings, biasing member 78 is a spring, but it will be appreciated that this could be a bellows or dual actuation system in which fluid force on the upper side of piston 72 pushes piston 72 downward. In FIG. 2, the valve assembly is shown in the closed position. Valve tip 14 is engaged with seat ring 32 and prevents and fluid from flowing past. Seal ring 44 also prevents the passage of fluid past valve seat body 34. Likewise, seal rings 73 prevent fluid flow past piston 72. As best seen with reference to FIG. 5 when fluid enters the gas lift assembly through inlet ports 64, the fluid pressure moves piston 72 upwards. This lifts valve member 12 up away from valve seat 30 and allows fluid to flow downward, past check valve 68 and out through outlet ports 66. When fluid ceases to enter inlet ports 64, or if the fluid pressure is less than the force exerted by biasing member 78, piston 72 lowers and valve member 12 again engages valve seat 30.

[0017]In one embodiment, the tip 14 and/or the ring 32 are made from a superhard material. In another embodiment, only frustoconical portion 18 of tip 14 may be made from superhard material. In a preferred embodiment the superhard material is polycrystalline diamond.

[0018]The valve of the present invention provides advantages over the prior art valves. The inclusion of the superhard material in the plug enables the plug to better withstand high pressure drops, e.g., those experienced with the choke valve body when compared to traditional choke plugs. Additionally, the inclusion of the superhard material in at least a portion of the seating surface makes the seat resistant to the wear which tends to result from the contact between the plug and the surface. Further, the overall durability of the entire fluid-handling system is improved.

[0019]Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.