WO1996026376A1

WO1996026376A1 - Improved valve plunger

Info

Publication number: WO1996026376A1
Application number: PCT/US1996/002445
Authority: WO
Inventors: Douglas A. Jensen; Debabrata Ghosh
Original assignee: Petrovalve International, Inc.
Priority date: 1995-02-23
Filing date: 1996-02-23
Publication date: 1996-08-29
Also published as: AU5172696A

Abstract

A composite valve plunger (10) for contacting a valve seat (14) within a fluid carrying housing (20) in a well. A valve member (16) having an arcuate surface (40) is guided by a valve stem (44) to reciprocate within the housing (20). When the valve member (16) contacts the valve seat (14), the flow of fluid through the housing (20) is blocked. The valve stem (44) can be formed with first (46) and second (48) sections. The valve member (16) can translate along the valve stem (44) or can be contained by the first (46) and second (48) valve stem sections to prevent rotational and translational movement.

Description

IMPROVED VALVE PLUNGER

This patent application is a continuation-in-part application based on United States Serial No. 08/184,119, entitled "Improved Plunσer for a Ball and Seat-type Check Valve, filed January 21, 1994, now abandoned.

The present invention relates to an improved valve for controlling the flow of fluid in a well. More particularly, the present invention relates to an improved valve having a plunger formed with a stem and valve member.

BACKGROUND OF THE INVENTION

Valves selectively control the flow of fluids from wells. In oil and gas wells, rod operated downhole pumps incorporate a standing valve and a traveling valve to control the flow of well fluids. When the rod lifts to raise well fluids to the surface, a plunger in the standing valve opens to permit the flow of well fluids into the production tubing. When the rod is lowered, the plunger seats against a valve seat to prevent the backflow of the fluids from the tubing into the formation.

Conventional oilfield check valves such as standing valves are formed with a ball and valve seat. When the rod is lowered within the production tubing, the standing valve ball seats against the valve seat and seals the production tubing to prevent the backflow of well fluids. The forces acting on the ball are extremely large and repeatedly force the ball against the valve seat. The forces acting against the ball generally include the weight of the flu in the production tubing and the downward movement of the rod, less frictional forces within the tubing. If the rod cycles te times per minute, the ball is forced against the valve seat 14,400 times per day, or 5,256,000 times per year. Consequentl the extreme wear conditions in wells such as oil and gas wells require the periodic repair and replacement of valves and valve components.

United States Patent No. 5,117,861 to McConnell et al. disclosed an improved valve for wells. This invention incorporated a plunger having an arcuate surface for contacting valve seat, and having a valve stem for guiding the movement of the plunger within a valve cage. The stem guided plunger significantly improved the valve life over ball and cage valves previously used in oilfield operations.

In addition to the repeated cycling experienced by well valves, enormous forces act against the valve components. Thes forces include the impact forces between the valve element and valve seat, bending forces acting between the valve element and valve stem, and erosive forces caused by contact with abrasive contaminants in the well fluids. A need exists for an improved valve that can endure the forces acting on the valve components and that can withstand the erosive effects of contaminants with the formation fluids. SUMMARY OF THE INVENTION

The present invention provides an improved valve plunger for contacting a valve seat within a fluid carrying housing in a well. A valve member reciprocates along an axis within the housing, and the valve member has an arcuate surface for selectively contacting the valve seat. An aperture in the valve member is coincident with the reciprocation axis, and a valve stem is engaged with the valve member through the aperture. A valve lock engages the valve stem with the valve member.

In other embodiments of the invention, the valve stem and the valve lock can be connected with a threaded connection positioned within the aperture. A seal can be located between the valve stem and the valve member to prevent migration of fluid therebetween. The valve member can be attached to the valve stem, or the valve member can reciprocate along the valve stem. The valve member and valve stem can be positioned within a housing so that the valve member contacts a valve seat to selectively control the movement of well fluid through the housing.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a valve within a production tubing. Figure 2 illustrates a valve member engaged with a valve stem.

Figure 3 illustrates a valve member engaged with two valve stem sections connected outside of the valve member aperture. Figure 4 illustrates a valve stem section having a threaded end connection.

Figure 5 illustrates a valve stem section for engagement with the threaded end shown in Figure 4.

Figure 6 illustrates a valve member engaged with a valve stem and valve stem lock.

Figure 7 illustrates a valve member bonded to a valve stem.

Figure 8 illustrates a valve member engaged with a valve stem for translational movement along the valve stem.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention discloses an improved valve for selectively controlling the flow of fluids in wells such as wate wells and hydrocarbon producing wells. In particular, the invention includes a composite valve plunger for contacting a valve seat to block the flow of well fluids. As used herein, the term "composite" means a component having at least two separate elements.

Referring to Figure 1, standing valve or check valve 10 is connected to production tubing 12 to selectively block the flow of well fluids (not shown) through valve 10. Valve 10 generally comprises valve seat 14 and valve member 16. Valve seat 14 can be installed within tubing 12 by connecting sub 18 to barrel housing 20 with threaded connection 22 between sub 18 and housing 20. The other end of housing 20 is connected to tubing 12 with threaded connection 24 between housing 20 and tubing 12. In one embodiment of the invention, cage 26 can be positioned within housing 20 to guide movement of valve member 16. As illustrated in Figure 1, cage 26 can comprise a lower ring 28, upper web 30 transverse to the axis of tubing 12, and longitudinal ribs 32 connecting ring 28 and web 30. Ribs 32 form windows 34 which serve as flow passages for the formation fluids through valve 10 when valve member 16 is not in contact with seat 14. In other embodiments of the invention, cage 26 can be replaced with a different form of web 30 that is adapted to be attached directly to housing 20.

Seat 14 is preferably formed from a hard material such as a metal. Seat 14 includes aperture 36 for permitting the flow of formations fluids therethrough. Preferably, seat aperture 36 includes beveled surface 38 which can be linear or arcuate in crossection. Surface 38 contacts valve member 16 and is preferably polished or hardened to reduce wear created by valve member 16.

Valve member 16 has an axis substantially coincident with the axis of tubing 12, and this axis is defined herein as the "reciprocation axis." Referring to Figure 2, valve member 16 has arcuate surface 40 for contacting surface 38 of seat 14. Upper surface 42 of valve member 16 is substantially transverse to the reciprocation axis and shapes valve member 16 as a semispherical ball to eliminate unnecessary weight of valve member 16. Valve stem 44 is engaged with valve member 16 through aperture 45. Aperture 45 has an axis substantially coincident with the reciprocation axis identified above.

As shown by the embodiment in Figure 2, first valve stem section 46 of valve stem 44 extends from upper surface 42 and second valve stem section 48 of valve stem 44 extends from arcuate surface 40. End 50 of first valve stem section 46 is slidably engaged with guide aperture 52 through web 30, and end 54 of second valve stem section 48 is slidably engaged with guid aperture 56 proximate to seat 14. As illustrated, aperture 52 and guide 56 cooperate to guide the reciprocation of valve stem 44 and valve member 16 along the reciprocation axis within housing 20.

As shown in Figure 1, arcuate surface 40 of valve member 16 is in contact with surface 38 of seat 14 to block the flow of fluid through valve 10. When valve member 16 is removed from this contact, the fluids will flow through seat aperture 36 unti valve member 16 is reurged into contact with seat 14.

Referring to Figure 2, arcuate surface 40 is preferably formed with a material resistant to wear caused by contact with seat 14. In addition, surface 40 is preferably formed with a material resistant to erosion caused by sand and other solids within the formation fluid. Because of the large bending moment acting on valve stem 44, valve stem 44 is preferably constructed from a material having high strength and ductility.

As shown in Figure 2, valve stem 44 is positioned within aperture 45 through valve member 16. Valve stem section 46 can be attached to valve stem section 48 with mechanical techniques such as the threaded connection 58 illustrated, by welding techniques, or by other bonding techniques such as glues or adhesives. In one embodiment of the invention, threaded connection 58 is positioned within aperture 45. Since threaded connection 58 forms the weakest part of valve stem section 46, the positioning of threaded connection in aperture 45 substantially reduces the bending moments acting on threaded connection 58. This occurs because aperture 45 operates as a sleeve to strengthen threaded connection 58.

Valve stem section 46 includes shoulder 60, and valve stem section 48 includes shoulder 62. Shoulders 60 and 62 have a dimension greater than the dimension of aperture 45 perpendicular to the reciprocation axis. Shoulder 60 is sized to counteract the impact forces exerted against valve member 16 due to contact with valve seat 14. As shown in Figure 2, shoulders 60 and 62 limit the travel of valve member 16 along valve stem 44, and can be configured to mechanically clamp valve member 16 therebetween. This feature permits a strong connecting engagement between valve stem 44 and valve member 16 without requiring welding or other processes to form the bond. The elimination of welding avoids problems associated with the heating of certain materials, and the elimination of adhesives such as glues eliminates problems associated with high well temperatures and cyclical loading. It will be appreciated that the mechanical connection formed by threaded connection 58 shows only one embodiment of the invention, and that valve stem 44 and valve member 16 can be engaged with welding or adhesive techniques.

Shoulder 60 includes recess 64 for retaining seal 66. Seal 66 prevents migration of the well fluid between vaive stem 44 an valve member 16, and therefore eliminates interior erosion cause by such migration of the well fluid. Seal 66 can be formed from elastomers or other synthetic materials chosen for compatability with the well fluid temperature and chemical composition.

Referring to Figure 3, another embodiment of the invention is shown, wherein valve stem 68 is formed with first valve stem section 70, shown in detail in Figure 4, and second valve stem section 72, as shown in detail in Figure 5. Stem section 70 includes shoulder 74 which incorporates threaded box end 76. Stem section 72 includes threaded end 78 for threaded engagement with box end 76. This embodiment of the invention is advantageous when additional tensile strength is required in valve stem section 70. Shoulder 74 can provide such additional tensile strength without enlarging the size of aperture 45 through valve member 16. As shown in Figure 5, the portion of stem section 72 in contact with valve member 16 can include external grooves 79 to provide a friction fit between stem section 72 and valve member 16. Stem section 72 can also includ shoulder 80 to limit movement of valve member 16 along the stem section 72.

As shown in Figure 6, valve stem 82 can be connected with stop 84 to engage valve stem 82 with valve member 16. Stop 84 can be configured in different ways such as a pin through valve stem 82, a lock washer, a fixed shoulder, or other configuration. Stop 84 operates in a fashion similar to that of shoulder 62 in Figure 2 to limit the movement of valve member 16 along the valve stem. Stop 84 can be formed before valve stem 82 is installed, or can be connected after valve stem 84 is engaged with valve member 16.

As shown in Figure 7, other embodiments of the invention can be constructed without mechanical connections between valve stem sections. As shown in Figure 7, first valve stem section 86 is engaged with second valve stem section 88 and valve member 16 with epoxy 90. Alternatively, epoxy 90 can be replaced with welding or other adhesion techniques suitable for the materials and well fluid conditions.

Figure 8 illustrates another embodiment of the invention wherein valve stem 92 is substantially stationary in housing 20, and valve member 16 reciprocates along stem 92. In one embodiment of the invention as shown, valve stem 92 can be constructed from first valve stem section 94 and second valve stem section 96. This embodiment of the invention experiences frictional wear between aperture 45 of valve member 16 and valve stem 92 as valve member 16 reciprocates within housing 20. Dynamic seal 98 can be positioned to limit erosive wear caused by the migration of well fluids between valve stem 92 and valve member 16, and stop 100 limits travel of valve member 16.

The invention improves known technology because the materials typically used in plungers such as valve member 16 do not resist mechanical cracking failure caused by cyclic bendin moments. The invention permits materials such as stainless st to be used as the valve stem components. Accordingly, the invention uniquely combines the benefits of the two classes of materials, and provides a strong connection for combining disparate components.

The present invention provides a unique apparatus for resisting erosion induced by the formation fluids and for resisting failure caused by cyclic bending moments. The invention is useful in any well, but is particularly useful in wells having an environment subject to corrosion, erosive elements, and high temperatures. It will be appreciated that unique structure of the invention permits the materials for th seat, valve member, and valve stem to be designed for specific corrosive, erosion, and temperature well conditions.

Although the invention has been described in terms of certain preferred emnbodiments, it will be apparent to those o ordinary skill in the art that various modifications can be ma to the inventive concepts without departing from the scope of invention. The embodiments shown herein are merely illustrati of the inventive concepts and should not be interpreted as limiting the scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A composite valve plunger for contacting a valve seat positioned within a fluid carrying housing in a well, comprising: a valve member for reciprocating along an axis within the housing, wherein said valve member has an arcuate surface for selectively contacting the valve seat to prevent the fluid from moving through the housing; an aperture through said valve member which is coincident with said reciprocation axis; a valve stem engaged with said valve member so that said valve stem extends through said aperture, wherein said valve stem is further engaged with the housing to guide the reciprocation of said valve member; and a valve stem lock for engaging said valve stem with said valve member.

2. A valve plunger as recited in Claim 1, wherein said valve stem includes one end of a threaded connection, and wherein said valve stem lock includes a complementary end to said threaded connection for engagement with said valve stem.

3. A valve plunger as recited in Claim 2, wherein said threaded connection is positioned within said aperture.

4. A valve plunger as recited in Claim 1, wherein said valve stem and said valve stem lock are detachable.

5. A valve plunger as recited in Claim l, wherein said valve stem is welded to said valve member.

6. A valve plunger as recited in Claim 1, wherein said valve stem is bonded to said valve member.

7. A valve plunger as recited in Claim 1, further comprising a seal between said valve stem and said valve member to prevent the migration of the fluid therebetween.

8. A valve plunger as recited in Claim l, further comprising a shoulder attached to said valve stem and in contac with said valve member to limit translational movement of said valve member along said valve stem.

9. A valve plunger as recited in Claim 8, wherein said valve stem lock has a dimension, greater than the dimension of said aperture perpendicular to said reciprocation axis, to limi translational movement of said valve member along said valve stem.

10. A valve plunger as recited in Claim 1, wherein said valve stem is substantially stationary within the housing, and wherein said valve stem lock permits reciprocation of said valve member along said valve stem.

11. A composite valve plunger for contacting a valve seat within a fluid carrying housing in a well, comprising: a valve member for reciprocating along an axis within the housing, wherein said valve member has an arcuate surface for selectively contacting the valve seat to prevent the fluid from moving through said housing; an aperture through said valve member which is coincident with said reciprocation axis; a first valve stem section coincident with said reciprocation axis and extending outwardly from said valve member; and a second valve stem section connected to said first valve stem section and extending outwardly from said valve member and opposite said first valve stem section, wherein said first and second valve stem sections guide the reciprocation of said valve member along said reciprocation axis.

12. A valve plunger as recited in Claim 11, wherein said first stem section and said second stem section are connected by a threaded connection.

13. A valve plunger as recited in Claim 11, wherein the connection between said first stem section and said second stem section is positioned within said aperture.

14. A valve plunger as recited in Claim 11, further comprising a seal between said first valve stem section and said valve member to prevent the migration of the fluid therebetween.

15. A valve for selectively permitting the flow of fluid through a valve seat in a well, comprising: a housing defining an interior space for containing the valve seat; a valve member for reciprocating along an axis within said housing, wherein said valve member has an arcuate surface for selectively contacting the valve seat to prevent the fluid from moving through said housing; an aperture through said valve member which is coincident with said reciprocation axis; a valve stem engaged with said valve member so that said valve stem extends through said aperture, wherein said valve stem is further engaged with said housing to guide the reciprocation of said valve member; and a valve stem lock connected to said valve stem for engaging said valve stem with said valve member.

16. A valve as recited in Claim 15, further comprising a seal between said valve stem and said valve member for preventing migration of the fluid therebetween.

17. A valve as recited in Claim 15, wherein said valve stem lock and said valve stem are connected at a position within said aperture.

18. A valve as recited in Claim 15, further comprising first and second guides attached to said housing for guiding the opposite ends of said valve stem along said reciprocation axis as said valve member reciprocates within said housing.

19. A valve as recited in Claim 15, wherein said valve stem is substantially stationary within said housing, and wherein said valve stem lock permits reciprocation of said valve member along said valve stem.

20. A valve as recited in Claim 15, wherein said valve stem lock engages said valve stem with said valve member to prevent rotational and translational movement therebetween.