GB2431677A

GB2431677A - Flapper check valve to prevent backflow when a pump is deactivated

Info

Publication number: GB2431677A
Application number: GB0621713A
Authority: GB
Inventors: Jeffrey John Lembcke; Robert J Coon
Original assignee: Weatherford Lamb Inc
Current assignee: Weatherford Lamb Inc
Priority date: 2005-10-31
Filing date: 2006-10-31
Publication date: 2007-05-02
Anticipated expiration: 2026-10-31
Also published as: GB0621713D0; CA2565998C; CA2710008A1; CA2710008C; US20070095545A1; CA2565998A1; GB2431677B; NO20064945L

Abstract

The check valve is intended to provide backflow protection when electrical submersible pumps (ESP) or similar are removed for repair or maintenance. The check valve comprises primarily flapper element 150 and sliding tube 155. When the pump is inoperative spring 130 moves the tube down, allowing the flapper to close of the fluid flow (Fig. 5) When the pump is operating fluid pressure against piston surfaces 120 forces the tube upwards against the spring. When the force is sufficient the tube pushes the flapper out of the flow path and holds it against the outside housing (Fig. 4). The piston elements are hinged to allow them to provide high resistance at low flow but present a minimal blockage at high flow. The valve should experience less wear then ball and seat type check valves and allow a wider flow path.

Description

I -

FULL BORE INJECTION VALVE

Embodiments of the present invention generally relate to controlling the flow of fluids in a welibore.

More particularly, the present invention relates to a valve for selectively closing a flow path through a weilbore in a single direction.

Generally, a completion string may be positioned in a well to produce fluids from one or more formation zones.

Completion devices may include casing, tubing, packers, valves, pumps, sand control equipment, and other equipment to control the production of hydrocarbons. During production, fluid flows from a reservoir through perforations and casing openings into the welibore and up a production tubing to the surface. The reservoir may be at a sufficiently high pressure such that natural flow may occur despite the presence of opposing pressure from the fluid column present in the production tubing. However, over the life of a reservoir, pressure declines may be experienced as the reservoir becomes depleted. When the pressure of the reservoir is insufficient for natural flow, artificial lift systems may be used to enhance production. Various artificial lift mechanisms may include pumps, gas lift mechanisms, and other mechanisms. One type of pump is the electrical submersible pump (ES?) An ESP normally has a centrifugal pump with a large number of stages of impellers and diffusers. The pump is driven by a downhole motor, which is typically a large three-phase AC motor. A seal section separates the motor from the pump for equalizing internal pressure of lubricant within the motor to that of the well bore. Often,

I

additional components may be included, such as a gas separator, a sand-separator, and a pressure and temperature measuring module. Large ESP assemblies may exceed 100 feet in length.

The ESP is typically installed by securing it to a string of production tubing and lowering the ESP assembly into the well. The string of production tubing may be made up of sections of pipe, each being about 30 feet in length.

If the ESP fails, the ESP may need to be removed from the weilbore for repair at the surface. Such repair may take an extended amount of time, e.g., days or weeks.

Typically, a conventional check valve is positioned below the ESP to control the flow of fluid in the welibore while the ESP is being repaired. The check valve generally includes a seat and a ball, whereby the ball moves off the seat when the valve is open to allow formation fluid to move toward the surface of the welibore and the ball contacts and creates a seal with the seat when the valve is closed to restrict the flow of formation fluid in the wellbore.

Although the conventional check valve is capable of controlling the flow of fluid in the welibore, there are several problems in using the conventional check valve in this type of arrangement. First, the seat of the check valve has a smaller inner diameter than the bore of the production tubing, thereby restricting the flow of fluid through the production tubing. Second, the ball of the check valve is always in the flow path of the formation fluid exiting the welibore which results in the erosion of the ball. This erosion may affect the ability of the ball

I-

to interact with the seat to close the valve and restrict the flow of fluidin the welibore.

Therefore, a need exists in the art for an improved apparatus and method for controlling the flow of fluid in the welibore.

The present invention generally relates to controlling the flow of fluids in a welibore. In one aspect, a valve for selectively closing a flow path through a welibore in a first direction is provided. The valve includes a body and a piston surface formable across the flow path in the first direction. The piston surface is formed at an end of a shiftable member annularly disposed in the body. The valve further includes a flapper member, the flapper member closable to seal the flow path when the shiftable member moves from a first position to a second position due to fluid flow acting on the piston surface.

In another aspect, a valve for selectively closing a flow path through a welibore in a single direction is provided. The valve includes a housing and a variable piston surface area formable across the flow path in the single direction. The valve also includes a flow tube axially movable within the housing between a first and a second position, wherein the variable piston surface is operatively attached to the flow tube. Further, the valve includes a flapper for closing the flow path through the valve upon movement of the flow tube to the second position.

In yet another aspect, a method for selectively closing a flow path through a welibore in a first direction is provided. The method includes positioning a valve in the welibore, wherein the valve has a body, a formable piston surface at an end of a shiftable member, and a flapper member. The method further includes reducing the flow in the first direction, thereby forming the piston surface.

Further, the method includes commencing a flow in a second direction against the piston surface to move the shiftable member away from a position adjacent the flapper member.

Additionally, the method includes closing the flapper member to seal the flow path through the welibore.

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

Figure 1 is a view illustrating a control valve disposed in a wellbore.

Figure 2 is a view illustrating the valve in an open position.

Figure 3 is a view illustrating the piston surface formed in a bore of the valve.

Figure 4 is a view taken along line 4-4 of Figure 3 to illustrate the piston surface.

Figure 5 is a view illustrating the valve in the closed position.

Figure 1 is a view illustrating a control valve 100 disposed in a wellbore 10. As shown, the control valve 100 is in a lower completion assembly disposed in a string of tubulars 30 inside a casing 25. An electrical submersible pump 15 may be disposed above the control valve 100 in an upper completion assembly. As illustrated, a polished bore receptacle and seal assembly 40 may be used to interconnect the electrical submersible pump 15 to the valve 100 and a packer arrangement 45 may be used to seal an annulus formed between the valve 100 and the casing 25. Generally, the valve 100 is used to isolate the lower completion assembly from the upper completion assembly when a mechanism in the upper completion assembly, such as the pump 15, requires modification or removal from the weilbore 10.

The electrical submersible pump 15 serves as an artificial lift mechanism, driving production fluids from the bottom of the welibore 10 through production tubing 35 to the surface. Although embodiments of the invention are described with reference to an electrical submersible pump, other embodiments contemplate the use of other types of artificial lift mechanisms commonly known by persons of ordinary skill in the art. Further, the valve 100 may be used in conjunction with other types of downho].e tools without departing from principles of the present invention.

Figure 2 is a view of the valve 100 in an open position. The valve 100 includes a top sub 170 and a bottom sub 175. The top 170 and bottom 175 subs are configured to be threadedly connected in series with the other downhole tubing. The valve 100 further includes a housing 105 disposed intermediate the top 170 and bottom 175 subs. The housing 105 defines a tubular body that serves as a housing for the valve 100. Additionally, the valve 100 includes a bore 110 to allow fluid, such as hydrocarbons, to flow through thevalve 100 during a production operation.

The valve 100 includes a piston surface 125 that is formable inthe bore 110 of the valve 100. The piston surface 125 shown in Figure 2 is in an unformed state. The piston surface 125 is maintained in the unformed state by a fluid force acting on the piston surface 125 created by fluid flow through the bore 110 of the valve 100 in the direction indicated by arrow 115. The piston surface 125 generally includes three individual members 120. Each member 120 has an end that is rotationally attached to a flow tube 155 by a pin 195 and each member 120 is biased rotationally inward toward the center of the valve 100.

Additionally, each member 120 is made from a material that is capable of withstanding the downhole environment, such as a metallic material or a composite material. Optionally, the members 120 may be coated with an abrasion resistant material.

As illustrated in Figure 2, the valve 100 also may include a biasing member 130. In one embodiment, the biasing member 130 defines a spring. The biasing member 130 resides in a chamber 160 defined between the flow tube 155 and the housing 105. A lower end of the biasing member 130 abuts a spring spacer 165. An upper end of the biasing member 130 abuts a shoulder 180 formed on the flow tube 155.

The biasing member 130 operates in compression to bias the flow tube 155 in a first position. Movement of the flow tube 155 from the first position to a second position compresses the biasing member 130 against the spring spacer 165.

The valve 100 further includes a flapper member 150 configured to seal the bore 110 of the valve 100. The flapper member 150 is rotationally attached by a pin 190 to a portion ofthe housing 105. The flapper member 150 pivots between an open position and a closed position in response to movement of the flow tube 155. In the open position, a fluid pathway is created through the bore 110, thereby allowing the flow of fluid through the valve 100.

Conversely, in the closed position, the flapper member 150 blocks the fluid pathway through the bore 110, thereby preventing the flow of fluid through the valve 100.

As shown in Figure 2, a lower portion of the flow tube 155 is disposed adjacent the flapper member 150. The flow tube 155 is movable longitudinally along the bore 110 of the valve 100 in response to a force on the piston surface 125. Axial movement of the flow tube 155, in turn, causes the flapper member 150 to pivot between its open and closed positions. In the open position, the flow tube 155 blocks the movement of the flapper member 150, thereby causing the flapper member 150 to be maintained in the open position. In the closed position, the flow tube 155 allows the flapper 150 to rotate on the pin 190 and move to the closed position. It should also be noted that the flow tube substantially eliminates the potential of contaminants from interfering with the critical workings of the valve 100.

Figure 3 illustrates the piston surface 125 formed in the bore of the valve 100. To seal the bore 110, the flow of fluid through the bore 110 of the valve 100 in the direction indicated by the arrow 115 is reduced. As the flow of fluid is reduced, the fluid force holding the piston surface 125 in the unformed state becomes less than the biasing force on the piston surface 125. At that point, each member 120 of the piston surface 125 rotates around the pin 195 toward the center.of the valve 100 to form the piston surface 125 illustrated in Figure 4. After the piston surface 125 is formed, the flow of fluid in the direction indicated by arrow 145 is commenced, thereby creating a force on the piston surface 125. As the force on the piston surface 125 increases, the force eventually becomes stronger than the force created by the biasing member 130. At that point, the force on the piston surface 125 urges the flow tube 155 longitudinally along the bore of the valve 100.

Figure 5 is a view illustrating the valve 100 in the closed position. After the piston surface 125 is formed, the flow tube 155 moves axially in the valve 100. This moves the lower end of the flow tube 155 out of its position adjacent the flapper member 150. This, in turn, allows the flapper member 150 to pivot into its closed position. In this position, the bore 110 of the valve 100 is sealed, thereby preventing fluid communication through the valve 100. More specifically, flow tube 155 in the closed position no longer blocks the movement of the flapper member 150, thereby allowing the flapper member 150 to pivot from the open position to the closed position and seal the bore 110 of the valve 100.

The flapper member 150 in the closed position closes the flow of fluid through the bore 110 of the valve 100, therefore no fluid force in the bore 110 acts on the members 120. To move the flapper member 150 back to the open position, the flow of fluid in the direction indicated by arrow 145 is reduced and the fluid on top of the flapper member 150 is pumped or sucked of f the top of the flapper member 150. At a predetermined point, the biasing member biasing the flapper member 150 is overcome and subsequently the biasing member 130 extends axially to urge the flow tube longitudinally along the bore 110 until a portion of the flow tube 155 is adjacent the flapper member 150. In this manner, the flapper member 150 is back to the open position, thereby opening the bore 110 of the valve 100 to flow of fluid therethrough, as illustrated in Figure 2.

In one embodiment, the valve 100 may be locked in the open position as shown in Figure 2 by disposing a tube (not shown) in the bore 110 of valve 100. The tube is configured to prevent the axial movement of flow tube 155 from the first position to the second position by preventing the formation of the piston surface 125. Thus, the flapper member 150 will remain in the open position and the valve will be locked in the open position. To lock the valve 100, the tube is typically pulled into the bore 110 from a position below the valve 100. In a similar manner, the valve 100 may be unlocked by removing the tube from the bore of the valve 100.

Although the invention has been described in part by making detailed reference to specific embodiments, such detail is intended to be and will be understood to be instructional rather than restrictive. For instance, the valve may be used in an injection well for controlling the flow of fluid therein. It should be also noted that while embodjments of the invention disclosed herein are described in connection with a valve, the embodiments described herein may be used with any well completion equipment, such as a packer, a sliding sleeve,..a landing nipple, and the like.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claima: 1. A valve for selectively closing a flow path through a

welibore in a first direction, the valve comprising: abody; a piston surface formable across the flow path in the first direction, the piston surface formed at an end of a shiftable member annularly disposed in the body; and a flapper member, the flapper member closable to seal the flow path when the shiftable member moves from a first position to a second position due to fluid flow acting on the piston surface.

2. The valve of claim 1, wherein the piston surface includes a plurality of members.

3. The valve of claim 2, wherein each member is annularly disposed within the shiftable member.

4. The valve of claim 2 or claim 3, wherein each member is biased inward toward a centerline of the body.

5. The valve of any preceding claim, wherein the piston surface is formable across the flow path upon fluid flow in a second direction.

6. The valve of any preceding claim, wherein the flapper member is movable between an open position and a closed position.

7. The valve of any preceding claim, wherein the flow tube retains the flapper member in the open position when the flow tube is in the first position.

8. The valve of any preceding claim, wherein the piston surface is coated with an abrasion resistant material.

9. The valve of any preceding claim, wherein the shiftable member is biased in the first position by a biasing member.

A valve for selectively closing a flow path through a weilbore in a single direction, the valve comprising: a housing; a variable piston surface area formable across the flow path in the single direction; a flow tube axially movable within the housing between a first and a second position due to fluid flow acting on the variable piston surface; and a flapper for closing the flow path through the valve upon movement of the flow tube to the second position.

11. The valve of claim 10, wherein the variable piston surface includes a plurality of members.

12. The valve of claim 11, wherein each member is movable between a smaller surface area position and a larger surface area position.

13. The valve of claim 12, wherein each member is biased in the larger surface area position.

14. The valve of any of claims 10 to 13, wherein the variable piston surface area is formable across the flow path upon fluid flow in a direction opposite the single direction.

15. A method for selectively closing a flow path through a weilbore in a first direction, the method comprising: positioning a valve in the weilbore, the valve having a body, a formable piston surface at an end of a shiftable member, and a flapper member; reducing the flow in the first direction, thereby forming the piston surface; commencing a flow in a second direction against the piston surface to move the shiftable member away from a position adjacent the flapper member; and closing the flapper member to seal the flow path through the weilbore.

16. The method of claim 15, wherein the piston surface includes a plurality of members.

17. The method of claim 16, further including moving the plurality of members from an open position to a closed position to form the piston surface.

18. The method of claim 16 or claim 17, further including biasing the plurality of members in the closed position.

19. The method of any of claims 15 to 18, further including reducing the flow in the second direction to move the shiftable member adjacent the flapper, thereby opening the flow path in the first direction.

20. The method of any of claims 15 to 19, further including locking the valve in an open position to maintain the flow path through the welibore.