US3782461A

US3782461A - Pressurized chamber well safety valve

Info

Publication number: US3782461A
Application number: US00148607A
Authority: US
Inventors: F Watkins
Original assignee: Camco Inc
Current assignee: CAMCO INC US; Camco International Inc
Priority date: 1971-06-01
Filing date: 1971-06-01
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: GB1371216A

Abstract

In a well safety valve for controlling the flow through a well conduit which has a pressurized chamber acting to move the valve toward the closed position and control pressure means extending from the well surface acting to move the valve toward the open position, the improvement of insuring that the control pressure is applied to all of the seals enclosing the pressurized chamber and that the pressure in the well conduit is isolated from the pressurized chamber seals to provide a fail safe valve. Passageway means extending from the control pressure to a position to apply the control pressure against the pressurized chamber seals on a side remote from the pressurized chamber, and seal means between the interior of the well conduit and said control pressure thereby isolating the pressurized chamber from the pressure in the well conduit.

Description

United States Patent [191 Watkins Jan. 1,1974

[ PRESSURIZED CHAMBER WELL SAFETY VALVE [75] inventor: Fred E. Watkins, Houston, Tex.

[73] Assignee: Cameo, Incorporated, Houston, Tex.

[22] Filed: June 1, 1971 [21] Appl. No.1 148,607

Primary Examiner.lames A. Leppink AIl0rney-James F. Weiler, Jefferson D. Giller, William A. Stout, Paul L. DeVerter, Dudley R. Dobie, Jr. and Henry W. Hope [5 7] ABSTRACT In a well safety valve for controlling the flow through a well conduit which has a pressurized chamber acting to move the valve toward the closed position and control pressure means extending from the well surface acting to move the valve toward the open position, the improvement of insuring that the control pressure is applied to all of the seals enclosing the pressurized chamber and that the pressure in the well conduit is isolated from the pressurized chamber seals to provide a fail safe valve. Passageway means extending from the control pressure to a position to apply the control pressure against the pressurized chamber seals on a side remote from the pressurized chamber, and seal means between the interior of the well conduit and said control pressure thereby isolating the pressurized chamber from the pressure in the well conduit.

4 Claims, 4 Drawing Figures PATENTEUJAN H914 SHEET 2 OF 2 I /\IVENTOR PRESSURIZED CHAMBER WELL SAFETY VALVE BACKGROUND OF THE INVENTION Generally, it is old to provide a well safety valve such as shown in US. Pat. No. 3,078,923, and copending patent application Ser. No. 51,199, which generally control the fluid flow in a well conduit by means of a valve which is movable between an open and closed position and in which means are provided to move the valve toward the closed-position and a control pressure acts to move the valve toward an open position. If the means for moving the valve to the closed position include a pressurized chamber, the pressure in the pressurized chamber is suitably enclosed by seals. However, the seals sometimes fail and since the pressure in the well conduit may be lower than the pressure in the pressurized chamber, the valve closing force becomes impaired. The present invention is directed to an improved pressurized chamber safety valve for providing fail safe construction.

SUMMARY The present invention is directed to an improved well safety valve for controlling the flow through a well conduit in which a pressurized chamber acts to move the valve toward a closed :position, and control pressure means preferably extending from the well surface acts to move the valve toward an open position, and the pressurized chamber is isolated from the pressure in the well conduit.

A still further object of the present invention is the provision of applying the higher control pressure to all of the pressurized chamber seals thereby assuring that any failure of the seals will cause a leakage into the chamber of a higher pressure and consequently provide a higher closing force to insure a fail safe condition.

Still a further object of the present invention is to provide seals between the interior of the well conduit and the control pressure for isolating the pressurized chamber from pressure in the conduit and insuring that only the higher control pressure can leak into the pressurized chamber.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational drawing, partly in cross section, illustrating the present invention in use in one type of well installation having a mandrel in which the safety valve is responsive to the annulus pressure,

FIG. 2 is an elevational view, partly in cross section, illustrating the present invention in use in a well installation in which the control pressure is providedthrough a line to the well surface,

FIG. 3A is an enlarged elevational view, partly in cross section, illustrating the top portion of one form of the safety valve of the present invention, and

FIG. 3B is a continuation of FIG. 3A.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the present improvement in a pressurized chamber safety valve will be shown, for purposes of illustration only, as incorporated in a flapper type well safety valve and in various installations, it will be understood that the present invention may be used in other types of well safety valves using pressurized chambers for closing and in other types of installations.

Referring now to the drawings, and particularly to FIGS. 3A and 3B, one type of subsurface safety valve is shown utilizing the present invention generally indicated by the reference numeral 10. The apparatus 10 generally includes a body 12 adapted to be positioned in a well conduit such as an oil and/or gas well tubing to permit production therethrough under normal operating conditions but in which the valve may close or be closed in response to abnormal conditions such as might occur when the well overproduces, blows wild, or in the event of a failure of well equipment.

The safety valve body 12 generally includes an annular valve seat 14 therein and a flapper 16 connected to the body 12 by a pivot pin 18. Thus when the flapper 16 is in the upper position seated on the valve seat 14, the safety valve 10 is closed blocking flow upwardly therethrough. A sliding tube 20 is telescopically movable in the body 12 and through the valve seat 14.

As best seen in FIG. 3B, when the sliding tube 20 is moved to a downward position, the tube 20 pushes against the flapper 16 away from the valve seat 14. Thus the valve is held in the open position so long as the sliding tube 20 is in the downward position. When the sliding tube 20 is moved upwardly, the flapper 16 is allowed to move upwardly closing the valve by the action of a spring 22 and also by the action of the fluid flow moving upwardly through the bore 13 of the body 12.

Various forces may be provided to act on the sliding tube 20 to control its movement so that under normal conditions the sliding tube 20 will be in the downward position holding the flapper 16 away from and off of the valve seat 14 and the valve 10 will be open. When abnormal conditions occur, the sliding tube 20 will be moved upwardly allowing the flapper 16 to close shutting off flow through the well conduit. Thus, a chamber 24 may be provided between the sliding tube 20 and the body 12 and a piston 26 which is secured to or is a part of the sliding tube 20 is movable in the chamber 24. The chamber 24 below the piston 26 may be pressurized to a desired pressure through a dill valve 27. Thus, pressure in the pressurized chamber 24 acts against the bottom of the piston 26 in a direction to move the sliding tube upwardly to allow the flapper 16 to close and seat on the seat 14. In addition, this closing force may be assisted by providing a spring 28 in the chamber 24 which acts between a shoulder 30 on the body 12 and the bottom of the piston 26.

The safety valve 10 is controlled by the application or removal of pressure through ports 34 into a chamber 32 against the top of the piston 26 acting in opposition to the force of the pressure in the chamber 24 and the spring 28. Thus if pressure applied through ports 34 is of sufficient magnitude, the piston 26 and thus the tube 20 will be moved downward, forcing the flapper 16 off of the seat 14 and into full open position. If the pressure applied through ports 34 to the chamber 32 abovethe piston 26 is reduced sufficiently relative to the forces on the piston caused by the pressurized chamber 24 and the spring 28 the piston 26 will move upwardly carrying the tube 20 beyond the seat 14 allowing the flapper 16 to swing and close on the seat 14. The pressurized charge in chamber 24 and the force of the spring 28 may be selected and set at some predetermined value that will cause the safety valve 10 to open and close at desired pressures.

The safety valve 10 includes an upper seal 36 and a lower seal 38 about the exterior of body 12 for sealing in a well conduit and receiving the control pressure therebetween as best seen in FIGS. 1 and 2. As best seen in FIG. 1, the safety valve 10 of the present invention may be used in an installation similar to that shown in copending patent application Ser. No. l ,199 wherein a mandrel 40 is positioned in a well conduit or tubing 42 in a well casing 44. In this installation the pressure in the annulus 46 of the well casing 44 may flow into the side pocket 48 of the mandrel 40 and be applied to the safety valve of the present invention between the upper and

lower seals

36 and 38. The safety valve 10 is retrievably positioned in the main bore 50 of the mandrel 40 by retractable dogs 52 of a conventional well lock 54. Another type of installation in which the present safety valve 10 may be used is shown in FIG. 2 wherein the valve 10 is placed in a well tubing 56 and locked therein by a conventional well lock 58. A tubing 61 is provided to the surface to conduct the control pressure through a port 59 in the well conduit 56 at a position between the upper and

lower seals

36 and 38.

The pressurized chamber 24 is enclosed by a plurality of seals such as seal 60 on the piston 26, seal 62 in the dill valve 27, seal 64 which seals off a plug 66 which is inserted onto the dill valve 27 after the chamber 24 is pressurized, and seal 68 between the body 12 and the sliding tube 20. Obviously, with age or damage, the various seals enclosing the pressurized chamber 24 may become impaired and leak. However, the pressure in the bore 13 of the safety valve 10 and in the well conduit may be ofa lower pressure than the pressure in the pressurized chamber 24. Therefore, if the pressure in the chamber 24 should leak through a seal and into the bore 13 of the safety tube 10, the pressure in the chamber 24 would be lowered. This would adversely affect the closing force on the safety valve 10 and reduce its ability to close at a critical time creating the possibility of a failure of the safety valve 10 to perform its primary function. The present safety valve 10 is arranged such that all of the seals enclosing the pressurized chamber 24 are subjected to the control pressure, which isof a higher pressure than the pressure in the chamber 24. This insures that if any of the

seals

60, 64, 62 and 68 fail, any leakage will be into the pressurized chamber 24 from the higher pressure of the control pressure thereby causing the safety valve 10 to have higher closing forces thus providing a fail safe condition. Additionally, the pressure in the bore 13 of the safety valve 10 and well conduit is completely isolated from the seals enclosing the pressurized chamber 24.

That is, the control pressure,.which is confined between the upper and

lower seals

36 and 38, is applied through ports 34 and chamber 32 to one side of the seal 60 and is applied exteriorly of the body 12 to the

seals

62 and 64, and a passageway 70 is provided in the body 12 below the seal 68 whereby the control pressure may be applied against the side of the seal 68 which is remote from the chamber 24. Thus, if any of the

seals

60, 62, 64 or 68 should leak, they will be exposed to the higher control pressure which will then flow into the pressurized chamber 24 to increase the closing forces on the safety valve 10 thus providing a fail safe condition. I

Additionally, seal means are provided between the control pressure and the interior bore 13 of the safety valve 10 for isolating the pressurized chamber 24 and its seals from the pressure in the well conduit. Thus, a seal 72 is provided between the body 12 and the sliding tube 20 above the piston 26, and a lower seal 74 is provided between the body I2 and the sliding tube 20 below the passageway 'thereby completely isolating the pressure in the bore 13 from the

chamber seals

60, 62, 64 and 68. It is to be noted that if

seals

72, 74, 36 or 38 fail, they will not adversely affect the closing force of the pressurized chamber 24, but will merely lower the opening force of the control pressure in chamber 32 and in passageway 70 thereby allowing the valve 10 to close and provide an additional fail safe feature.

In operation, the safety valve 10 of the present invention may be retrievably positioned in any suitable installation such as shown in FIG. 1 or 2 by conventionally locking the safety valve 10 in place with a conventional well lock whereby the upper and

lower seals

36 and 38 encompass a control pressure, preferably extending to the well surface. Thus, in FIG. 1, safety valve 10 will be controlled by the pressure in the annulus 46 and in FIG. 2 the safety valve 10 will be controlled by the application of control pressure in the line 61. Thus if the flow pressure applied through the ports 34 to the top of the piston 26 is of sufficient mangitude, the piston 26 will move down overcoming the spring 28 and the pressurized chamber 24 forcing the tube 20 downwardly moving the flapper 16 off of the seat 14 and moving the valve into the full open position. And if the control pressure in chamber 32 is reduced sufficiently by control or failure of surface equipment, the pressurized chamber 24 and spring 28 will move the tube 20 upwardly closing the valve 10. And in the event that any of the seals fail, the valve 10 will only fail in a fail safe condition.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as others inherent therein.

What is claimed is:

1. In a well safety valve for controlling the flow through a well conduit, said valve being movable between an open and closed position, movable means including piston means controlling the opening and closing of said valve, seals which enclose a pressurized chamber, which chamber acts on said piston means to move the valve toward the closed position and control pressure means extending from the well surface acting on said piston means to move the valve toward an open position, wherein the improvement comprises,

passageway means extending from the control pressure means for applying control pressure against the pressurized chamber seals on a side remote from the pressurized chamber, and

seal means between the interior of the valve and said control pressure means for isolating the pressurized chamber from the pressure in the conduit for pro- I viding a fail safe valve.

2. In a well safety valve for controlling the flow through a well conduit, said valve being movable between an open and closed position, movable means including piston means for controlling the opening and closing of said valve, upper and lower first seal means on the exterior of the valve for sealing with the well conduit, a pressurized chamber in said valve between the upper and lower first seal means which acts on said piston means to move the valve toward the closed position, second seal means enclosing the pressurized chamber, and control pressure means extending from the well surface to between the upper and lower first seal means and acting on said piston means and against the pressurized chamber for moving the valve toward an open position, wherein the improvement comprises,

a passageway extending from a point below the second seal means and the chamber to a point exteriorly of the valve and between the upper and lower first seal means, and third seal means in the valve between the interior of the valve and below the passageway for isolating the pressurized chamber from the pressure interior of the valve for providing a fail safe valve. 3. In a well safety valve for controlling flow through a well conduit and having a body with an annular valve seat therein, a flapper valve pivotally connected to the body below the seat and movable upwardly into engagement with the seat for closing the valve and movable downwardly away from the seat for opening the valve, a sliding tube including piston means and telescopically movable in the body and through said seat, upper and lower first seal means on the exterior of the body for sealing with the well conduit, a pressurized chamber between the body and the sliding tube for acting on the piston means for moving the sliding tube upwardly for allowing the flapper valve to close the valve, second seal means enclosing the pressurized chamber, control pressure means extending from the well surface to a position between the upper and lower first seals and acting on the piston means and against the pressurized chamber for moving the sliding tube downwardly for opening the flapper valve, wherein the improvement comprises,

said seals enclosing the pressurized chamber being in communication with the control pressure on a side remote from the pressurized chamber, and seal means between the interior of the valve body and said control pressure for isolating the pressurized chamber from the pressure in the conduit for providing a fail safe valve. I 4. In a well safety valve for controlling flow through a well conduit and having a body with an annular valve seat therein, a flapper valve pivotally connected to the body below the seat and movable upwardly into engagement with the seat for closing the valve and movable downwardly away from the seat for opening the valve, a sliding tube including piston means and telescopically movable in the body and through said seat, upper and lower first seal means on the exterior of the body for sealing with the well conduit, a pressurized chamber between the body and the sliding tube for acting against the piston meansand moving the sliding tube upwardly for allowing the flapper valve to close the valve, second seal means above and below the chamber and between the body and the tube enclosing the pressurized chamber, control pressure means extending from the well surface to the exterior of the body between the upper and lower first seals and acting on the piston means and against the pressurized chamber for moving the sliding tube downwardly for opening the flapper valve, wherein the improvement comprises, a passageway extending from a point between said body and the tube below the second seal means and below the chamber to a point exteriorly of the body between the upper and lower first seal means, and a third seal means between the body and the tube below the passageway thereby isolating the pressurized chamber from the pressure in the well conduit for providing a fail safe valve.

Claims

1. In a well safety valve for controlling the flow through a well conduit, said valve being movable between an open and closed position, movable means including piston means controlling the opening and closing of said valve, seals which enclose a pressurized chamber, which chamber acts on said piston means to move the valve toward the closed position and control pressure means extending from the well surface acting on said piston means to move the valve toward an open position, wherein the improvement comprises, passageway means extending from the control pressure means for applying control pressure against the pressurized chamber seals on a side remote from the pressurized chamber, and seal means between the interior of the valve and said control pressure means for isolating the pressurized chamber from the pressure in the conduit for providing a fail safe valve.

2. In a well safety valve for controlling the flow through a well conduit, said valve being movable between an open and closed position, movable means including piston means for controlling the opening and closing of said valve, upper and lower first seal means on the exterior of the valve for sealing with the well conduit, a pressurized chamber in said valve between the upper and lower first seal means which acts on said piston means to move the valve toward the closed position, second seal means enclosing the pressurized chamber, and control pressure means extending from the well surface to between the upper and lower first seal means and acting on said piston means and against the pressurized chamber for moving the valve toward an open position, wherein the improvement comprises, a passageway extending from a point below the second seal means and the chamber to a point exteriorly of the valve and between the upper and lower first seal means, and third seal means in the valve between the interior of the valve and below the passageway for isolating the pressurized chamber from the pressure interior of the valve for providing a fail safe valve.

3. In a well safety valve for controlling flow through a well conduit and having a body with an annular valve seat therein, a flapper valve pivotally connected to the body below the seat and movable upwardly into engagement with the seat for closing the valve and movable downwardly away from the seat for opening the vAlve, a sliding tube including piston means and telescopically movable in the body and through said seat, upper and lower first seal means on the exterior of the body for sealing with the well conduit, a pressurized chamber between the body and the sliding tube for acting on the piston means for moving the sliding tube upwardly for allowing the flapper valve to close the valve, second seal means enclosing the pressurized chamber, control pressure means extending from the well surface to a position between the upper and lower first seals and acting on the piston means and against the pressurized chamber for moving the sliding tube downwardly for opening the flapper valve, wherein the improvement comprises, said seals enclosing the pressurized chamber being in communication with the control pressure on a side remote from the pressurized chamber, and seal means between the interior of the valve body and said control pressure for isolating the pressurized chamber from the pressure in the conduit for providing a fail safe valve.

4. In a well safety valve for controlling flow through a well conduit and having a body with an annular valve seat therein, a flapper valve pivotally connected to the body below the seat and movable upwardly into engagement with the seat for closing the valve and movable downwardly away from the seat for opening the valve, a sliding tube including piston means and telescopically movable in the body and through said seat, upper and lower first seal means on the exterior of the body for sealing with the well conduit, a pressurized chamber between the body and the sliding tube for acting against the piston means and moving the sliding tube upwardly for allowing the flapper valve to close the valve, second seal means above and below the chamber and between the body and the tube enclosing the pressurized chamber, control pressure means extending from the well surface to the exterior of the body between the upper and lower first seals and acting on the piston means and against the pressurized chamber for moving the sliding tube downwardly for opening the flapper valve, wherein the improvement comprises, a passageway extending from a point between said body and the tube below the second seal means and below the chamber to a point exteriorly of the body between the upper and lower first seal means, and a third seal means between the body and the tube below the passageway thereby isolating the pressurized chamber from the pressure in the well conduit for providing a fail safe valve.