SOFT SEAT RETENTION

Abstract

A device, such as a valve, having a soft seat disposed in a groove formed in and circumferentially along a hard seating surface of a hard seat and one or more retaining elements disposed in the groove in contact with the soft seat and the hard seat.

Description

BACKGROUND

This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.

The present disclosure relates generally to wellbore operations and equipment and more specifically to actuation devices for downhole tools (e.g., subsurface tools, wellbore tools) and methods of operation.

Hydrocarbon fluids such as oil and natural gas are produced from subterranean geologic formations, referred to as reservoirs, by drilling wells that penetrate the hydrocarbon-bearing formations. Once a wellbore is drilled, various forms of well completion components may be installed in order to control and enhance the efficiency of producing fluids from the reservoir and/or injecting fluid into the reservoir and/or other geological formations penetrated by the wellbore. In some wells, for example, valves are actuated between open and closed states to compensate or balance fluid flow across multiple zones in the wellbore. In other wells, an isolation valve may be actuated to a closed position to shut in or suspend a well for a period of time and then opened when desired. Often a well will include a subsurface valve to prevent or limit the flow of fluids in an undesired direction.

SUMMARY

A device according to one or more aspects of the disclosure includes a hard seat having a hard sealing surface that extends circumferentially about an axial bore and has an inner circumferential edge and an outer circumferential edge, a soft seat disposed circumferentially along the hard sealing surface between the inner and the outer circumferential edges. The device may include a groove formed in and circumferentially along the hard sealing surface between the inner and outer edges, the soft seat positioned in the groove and having a soft sealing surface positioned above the hard sealing surface. One or more retainer elements may be disposed in the groove between the soft seat and the hard seat for example to wedge the soft seat into connection with the hard seat.

An example of a well system includes a valve disposed with a tubular string and deployed downhole in a wellbore, the valve including a hard seat having a hard sealing surface extending circumferentially about an axial bore, a soft seat disposed circumferentially along the hard sealing surface between inner and outer circumferential edges of the hard sealing surface, and a flapper having a flapper sealing surface cooperative with the soft seat to provide a seal when the flapper is in a closed position. In accordance to some embodiment the soft seat is positioned in a groove in the hard sealing surface with one or more retainer elements disposed in the groove in contact with the soft seat and the hard seat.

An example of a method includes disposing a valve in a tubular string in a wellbore, the valve including a hard seat with a hard sealing surface extending circumferentially about an axial bore, a soft seat disposed circumferentially about the hard sealing surface between inner and outer circumferential edges of the hard seating surface, and a flapper having a flapper sealing surface cooperative with the soft seat to provide a seal when the flapper is in a closed position.

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 a schematic of a well system incorporating an embodiment of a downhole valve utilizing soft seat which is retained according to one or more aspects of the disclosure.

FIG. 2 is a sectional view of a valve incorporating a hard seat and a soft seat cooperative with a curved flapper according to one or more aspects of the disclosure.

FIG. 3 is a schematic illustration of soft seat retained with a curved hard sealing surface according to one or more aspects of the disclosure.

FIG. 4 is a schematic illustration of a valve showing a groove formed along a hard sealing surface according to one or more aspects of the disclosure.

FIGS. 5 and 6 illustrate positioning of retainer elements to hold a soft seat with a hard seat according to one or more aspects of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

As used herein, the terms connect, connection, connected, in connection with, and connecting may be used to mean in direct connection with or in connection with via one or more elements. Similarly, the terms couple, coupling, coupled, coupled together, and coupled with may be used to mean directly coupled together or coupled together via one or more elements. Terms such as up, down, top and bottom and other like terms indicating relative positions to a given point or element may be utilized to more clearly describe some elements. Commonly, these terms relate to a reference point such as the surface from which drilling operations are initiated.

Subsurface valves are commonly actuated to a first position (e.g., open) by the application of hydraulic pressure, for example from the surface, and biased to the second position (e.g., closed) by a biasing mechanism (stored energy assembly), such as an enclosed pressurized fluid chamber or a mechanical spring. The fluidic pressure may be applied to a piston and cylinder assembly, for example, that acts against the biasing force of the biasing mechanism to open and hold the valve opened. The biasing force acts on the piston to move it to a position allowing the closure member to move to the closed position when the actuating fluid pressure is reduced below a certain value.

Examples of some subsurface valves are disclosed in U.S. Pat. Nos. 4,161,219 and 4,660,646 and U.S. Patent Application Publications 2009/0266555, 2010/0006295 and 2010/0139923, which are all incorporated herein by reference.

FIGS. 1-6 illustrate embodiments of a device, generally denoted by the numeral 12, incorporating a soft seat 32 and a retainer 34 according to aspects of the disclosure. Device 12 has an inside diameter 7 defining an axial bore 36 through a hard seat 38 having a hard sealing surface 40, a flapper 30 is pivotally coupled to the hard seat (e.g., housing) to move between an open position and a closed position. By coupled, it is understood that flapper 30 may be directly coupled to hard seat 38 or indirectly coupled by an intermediate member. For example, flapper 30 is depicted pivotally connected by a hinge, for example pivot pin 31. Hard sealing surface 40 is cooperative with a flapper sealing surface 42 to provide a seal when flapper 30 is pivoted to a closed position. Hard seat 38 is generally described herein as being constructed of a metal material (e.g., carbon steel, stainless steel, etc.) and the hard sealing surface 40 and the flapper sealing surface 42 creating a metal-to-metal seal. Hard sealing surface 40 may comprise a non-metal material, such as a ceramic or other substantially non-pliable material.

Device 12 includes a soft seat 32 providing a pliable sealing surface 33 that is cooperative with the flapper sealing surface 42 for example to effect a better seal to gas flow relative to the hard sealing surface 40. A retainer 34 may be utilized to maintain soft seat 32 in position relative to the hard sealing surface when the flapper 30 is in the open position.

FIG. 1 is a schematic of a well system 10 incorporating an embodiment of a downhole tool 12 having a soft seat 32 according to one or more aspects of the present disclosure. Depicted well system 10 includes a wellbore 16 extending from a surface 18 and lined with casing 20. A tubular string 22 is disposed in wellbore 16. Downhole tool 12 is depicted in FIG. 1 as non-limiting embodiment of a subsurface flow control device (e.g., valve) connected within tubular string 22 for selectively controlling fluid flow through the tubular device 12 and tubular string 22. For example, subsurface valve 12 may be used to block the flow of reservoir fluid 2 through tubular string 22 to the surface when fluid 2 flows from formation 4 through tunnels 6 and into wellbore 16 and tubular string 22 under a greater pressure than desired.

Depicted valve 12 is operated in this example to an open position in response to a signal (e.g., electric signal, fluidic signal, electro-fluidic signal, mechanical signal) provided via control system 24. Depicted control system 24 includes a power source 26 operationally connected to actuator apparatus 14 to operate a closure member 30 (e.g., valve member, flapper) from the one position to another position. In FIG. 1, the closure member 30 is in a closed position blocking fluid flow through the bore of the tubular string 22. In the non-limiting embodiment depicted in FIG. 1, control system 24 is a fluidic (e.g., hydraulic) system in which fluidic pressure 26 is provided through control line 28 to actuator apparatus 14 which applies an operational force that moves the actuator apparatus in a first direction engaging and actuating closure member 30 to an open position allowing fluid in tubular string 22 to flow across closure member 30. Hydraulic pressure is maintained above a certain level to hold the closure member 30 in the open position. To actuate subsurface valve 12 to the closed position, as shown in FIG. 1, the hydraulic pressure via control line 28 is reduced below a certain level. As is known in the art, the hydraulic pressure is reduced below the level of the force that biases the closure member 30 to the closed position.

Referring specifically to FIGS. 2-4, soft seat 32 is for example a circular member formed of a pliable and/or low yield material such as, and without limitation, TEFLON, polyetheretherketon (PEEK), polytetrafluoroethylene (PTFE), other plastics and non-plastics such as pure nickel. In accordance to embodiments the soft seat 32 has a uniform thickness so that that is expands uniformly when heated. The hard sealing surface 40 is formed circumferentially about the bore 36 and has an inside circumferential edge 41 and an outer circumferential edge 43. A groove 44 is formed into the hard sealing surface 40 between the inside and outside edges 41, 43 and extends the circumferentially length of the hard sealing surface. The groove may be cut normal to the contact surface or along the longitudinal access.

In FIGS. 2-4 the flapper 30 is a curved flapper and the hard sealing surface 40 is curved and undulates along the perimeter between crests and valleys. The soft seat 32 may be utilized in a flat flapper designs as well. Traditional curved flapper valves that include both a soft seat and a hard seat utilize a two piece connection where the soft seat is connected for example along a peripheral edge of the hard seat by another hard seat or housing section. Cutting a groove 44 into the hard sealing surface 40 provides a stable pressure bearing surface.

When the flapper 30 is in the open position the soft seat 32 is retained in the groove 44 and in connection with the hard seat 38 by retainer 34 which is disposed in the groove 44 between the soft seat 32 and the hard seat 38 to wedge or squeeze the soft seat 32, below the soft sealing surface 33, into contact with the hard seat 38. The retainer element 34 may be located between the soft seat 32 and the inner circumferential edge 41 (i.e., on the inner side of the soft seat) or between the soft seat and the outer circumferential edge 41 (i.e., on the outer side of the soft seat). The retainer element 34 may take various forms, such as an elongated member, e.g. a wire, or a set of two or more elements such as spherical balls.

In some embodiments, the retainer element 34 may be disposed partially in an undercut groove 46 formed below the hard sealing surface 40 and between the groove 44 and the structural hard seat 38. The undercut groove 46 may be formed on the outer side of the groove 40 and soft seat and extend through the hard seat 38 to an opening 48 formed in the exterior surface 50 of the hard seat 38 for positioning the retainer or retainers 34 in the undercut groove.

FIG. 5 illustrates positioning a retainer 34, in the form of an elongated member such as wire in the undercut groove 46 to extend around the full or substantially full circumferentially length of the soft seat 32. The elongated retainer 34 is fed through the opening or port 48 of the undercut groove 46.

FIG. 6 illustrates positioning spherical retainers 34 in the undercut groove 46 to secure the soft seat in position. A spherical retainer 34 is inserted through port 48 into the undercut groove 46 and into contact with the soft seat 32. The soft seat 32 may rotated in the groove to move the first spherical retainer 34 circumferentially. A second spherical retainer 14 can then be fed through the port 48 into the undercut groove 46 and the soft seat 32 and second spherical retainer rotated circumferentially. The process can be repeated until the desired number of spherical retainers 34 are positioned in the undercut groove 46 and around the circumference of the soft seat 32.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the disclosure. Those skilled in the art should appreciate that they may readily use the disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the disclosure. The scope of the invention should be determined only by the language of the claims that follow.

The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. The terms “a,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded.

Claims

1. A device, comprising:

a hard seat comprising a hard sealing surface extending circumferentially about an axial bore and having an inner circumferential edge and an outer circumferential edge; and

a soft seat disposed circumferentially along the hard sealing surface between the inner and the outer circumferential edges.

2. The device of claim 1, wherein the hard sealing surface is curved.

3. The device of claim 1, wherein the soft seat is a circular member formed of a pliable material.

4. The device of claim 1, wherein the soft seat is positioned in a groove formed in the hard sealing surface.

5. The device of claim 1, further comprising:

a groove formed in and circumferentially along the hard sealing surface between the inner and outer edges, the soft seat positioned in the groove and having a soft sealing surface positioned above the hard sealing surface; and

a retainer element disposed in the groove and in contact with the soft seat and the hard seat.

6. The device of claim 5, wherein the retainer element is disposed between the soft seat and the outer circumferential edge.

7. The device of claim 5, wherein the retainer element is an elongated member.

8. The device of claim 5, wherein the retainer element is an elongated member extending circumferentially or substantially circumferentially along the length of the soft seat.

9. The device of claim 5, wherein the retainer element comprises two or more elements spaced circumferentially apart.

10. The device of claim 1, further comprising:

a groove formed in and circumferentially along the hard sealing surface between the inner and outer edges, the soft seat positioned in the groove and having a soft sealing surface positioned above the hard sealing surface;

an undercut groove formed below the hard sealing surface along circumferentially along the groove; and

a retainer element disposed in the groove and in contact with the soft seat and the hard seat.

11. The device of claim 10, wherein the hard sealing surface is curved.

12. The device of claim 10, wherein the retainer element is an elongated member.

13. The device of claim 10, wherein the retainer element comprises two or more elements spaced circumferentially apart.

14. The device of claim 1, further comprising a flapper having a flapper sealing surface cooperative with the soft seat to provide a seal when the flapper is in a closed position.

15. A well system, comprising:

a valve disposed with a tubular string and deployed downhole in a wellbore, the valve comprising: a hard seat comprising a hard sealing surface extending circumferentially about an axial bore and having an inner circumferential edge and an outer circumferential edge; a soft seat disposed circumferentially along the hard sealing surface between the inner and the outer circumferential edges; and a flapper having a flapper sealing surface cooperative with the soft seat to provide a seal when the flapper is in a closed position.

16. The system of claim 1, wherein the flapper is a curved flapper and the hard sealing surface is curved.

17. The system of claim 15, further comprising:

a groove formed in and circumferentially along the hard sealing surface between the inner and outer edges, the soft seat positioned in the groove and having a soft sealing surface positioned above the hard sealing surface; and

a retainer element disposed in the groove and in contact with the soft seat and the hard seat.

18. A method, comprising:

disposing a valve in a tubular string in a wellbore, the valve comprising: a hard seat comprising a hard sealing surface extending circumferentially about an axial bore and having an inner circumferential edge and an outer circumferential edge; a soft seat disposed circumferentially about the hard sealing surface between the inner and the outer circumferential edges; and a flapper having a flapper sealing surface cooperative with the soft seat to provide a seal when the flapper is in a closed position.

19. The method of claim 18, wherein the flapper is a curved flapper and the hard sealing surface is curved.

20. The method system of claim 18, wherein the valve further comprises:

a groove formed in and circumferentially along the hard sealing surface between the inner and outer edges, the soft seat positioned in the groove and having a soft sealing surface positioned above the hard sealing surface; and

a retainer element disposed in the groove and in contact with the soft seat and the hard seat.