US3826309A

US3826309A - Well safety valve

Info

Publication number: US3826309A
Authority: US
Inventors: G Tausch
Original assignee: Camco Inc
Current assignee: CAMCO INC US; Camco International Inc
Priority date: 1973-05-11
Filing date: 1973-05-11
Publication date: 1974-07-30
Anticipated expiration: 1991-07-30
Also published as: GB1448765A

Abstract

A well safety valve for use in a well tubing having a valve for engaging an annular valve seat for opening and closing the valve and operated by a sliding tube telescopically movable in the body and positioned below the valve means. Upward movement of the tube opens the valve and downward movement of the tube closes the valve. Means normally biasing said tube upwardly for holding the valve open and piston means connected to the tube and in communication with the exterior of the valve for moving the tube downwardly for closing the valve on increase in pressure exteriorly of the valve. A flapper valve pivotally connected to the body below the valve seat and movable upwardly into engagement with the seat for closing the valve and movable downwardly away from the seat for opening the valve. The biasing means including a gas chamber having a seal on each side of the chamber between the chamber and the interior of the tubing, and a bleed port leading from the side of each seal remote from the chamber to exteriorly of the body for preventing tubing pressure entering the chamber and providing a fail safe operation of the biasing chamber.

Description

United States Patent [191 Tausch Primary Examiner.lames A. Leppink Attorney, Agent, or Firm-Fulbright & Crooker [57] ABSTRACT A well safety valve for use in a well tubing having a [111 3,826,309 [451 July 30, 1974 valve for engaging an annular-valve seat for opening and closing the valve and operated by a sliding tube telescopically movable in the body and positioned below the valve means. Upward movement of the tube opens the valve and downward movement of the tube closes the valve. Means normally biasing said tube upwardly for holding the valve open and piston means connected to the tube and in communication with the exterior of the valve for moving the tube downwardly for closing the valve on increase in pressure exteriorly of the valve. A flapper valve pivotally connected to the body below the valve seat and movable upwardly into engagement with the seat for closing the valve and movable downwardly away from the seat for opening the valve. The biasing means including a gas chamber having a seal on each side of the chamber between the chamber and the interior of the tubing, and a bleed port leading from the side of each seal remote from the chamber to exteriorly of the body for preventing tubing pressure entering the chamber and providing a fail safe operation of the biasing chamber.

. 3 Claims, 2 Drawing Figures WELL SAFETY VALVE BACKGROUND OF THE INVENTION Generally, it is old to provide well safety valves such as shown in U.S. Pat. Nos. 3,045,760; 3,078,923; 3,265,134; which generally control the fluid flow in a well through a body actuated by a sliding tube telescopically movable in the body. However, there are several problems that exist with producing oil and gas wells which the present improved well safety valve is directed. One problem is that leaking threads in the well tubing allow high pressure production to enter the annulus between the well tubing and the well casing. The larger diameter well casing is not designed to withstand the high pressure of the oil and gas production flowingin the tube, and therefore the annulus pressure must be constantly monitored and relieved or the casing pipe will be ruptured. Another problem'is that when a large diameter well tubing is utilized, such as in the Middle East countries, it is difficult to kill such a well in the case of a well catastrophe. The high flow rates which may occur through large well tubing dilutes and lightens the drilling mud or work-over fluid that is pumped down the well tubing to kill the well. In such situations, it takes a high pump rate and considerable time to finally kill such a well.

The above mentioned problems can be overcome by a well safety valve of the present invention positioned near the lower extremity of the well tubing that closes whenever the pressure exteriorly of the tubing in the annulus between the well tubing and easing increases.

SUMMARY The present invention is directed to an improved well safety valve having a valve normally biased to the open position by a sliding tube telescopically movable in the body and positioned below the valve in which upward movement of the tube holds the valve in the open position and downward movement of the tube actuates the valve to the closed position.

A further object of the present invention is the provision of piston means connected to the tube and exposed to the pressure in the annulus between the tubing and the casing in which increased annulus pressure moves the tube downwardly closing the valve.

Yet a further object of the present invention is the provision of biasing means including a precharged gas chamber biasing the tube in an upward direction for keeping the valve open and in which tubing pressure is prevented from leaking into the chamber by providing a seal on each side of the chamber between the chamber and the interior of the well tubing. A bleed port is provided leading from each seal on the side of the seals remote from the chamber to the exterior of the body whereby the high pressure in the well tubing will not leak into the chamberto increase the force holding the valve open, but any pressure leak from the chamber may leak to the annulus for allowing the valve to close at a lower annulus pressure.

Still a furtherfeature is the provision of a well safety valve that will lock in the closed position but which may be reopened when casing pressure and other adverse conditions are overcome such as by being reopened with the use of suitable wireline operations.

Other and further objects, features and advantages will be apparent from the following description of a presently preferred embodiment of the invention, given for the purpose of disclosure and taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT While the present improvements in a well safety valve will be described, for purposes of illustration only in use with a flapper type well safety valve, it is understood that the present invention may be used with other types of well safety valves.

Referring now to the drawing, and particularly to FIGS. 1A and 18, one type of flapper subsurface well safety valve is shown utilizing the present invention,

generally indicated by the reference numeral 10. The apparatus 10 generally includes a body 12 having threaded connections 14 and 16 adapted to be connected in a well tubing positioned inside of a well casing (not shown) to permit production of oil and gas through the tubing under normal operating conditions but in which the valve 10 may close in response to abnormal conditions such as might occur when the well overproduces, blows wild, the annulus pressure between the tubing and the casing exceeds a desired amount, or in the event of failure in the well equip ment.

The well safety valve 10 generally includes an annular valve seat 20 and a flapper valve 16 positioned therebelow and connected to the body 12 by a pivot pin 18. Thus, when the flapper valve 16 is in the upward position seated on the valve seat 20, as best shown in FIG. 1A, the safety valve 10 is closed blocking flow therethrough. A spring 22 is provided which 'yieldably urges the flapper valve 16 toward its seating position on the valve seat 20. When the flapper valve,l6 is held in the open position, as shown in dotted outline in FIG. 1A, the valve is open and production of oil and gas may freely flow-through the safety valve 10. I

A sliding tube 24 is telescopically movable in the body 12 and through the valve seat 20. As best seen in FIG. 1A, when the sliding tube 24 is moved to the downward position, the flapper valve 16 is released and is allowed to move upwardly, closing the valve by the action of the spring 22 and also by the action of fluid flow moving upwardly through the bore 13 of the valve 10. And as best seen in dotted outline in FIG. 1A, when the sliding tube 24 is held in the upward position, the tube 24 extends past the flapper valve 16 and through the valve seat 20 and the valve 16 is held in the open position so long as the sliding tube 24 is held in the upward position.

Normally, the sliding tube 24 is biased to itsupward position holding the flapper valve 16 away from and off of the valve seat 20, but when abnormal conditions occur, the sliding tube 24 will be moved downwardly allowing the flapper valve 16 to close shutting off flow through the production well tubing.

' Referring now to FIG. 18, a precharged gas chamber 30 may be provided acting against'a downwardly directed piston 32 connected to the sliding tube 24. Gas pressure may be injected into the chamber 30 through a dill valve'34 to any desired pressure. The pressure in the chamber 30 acts against the piston 32 to bias the tube 24 in an upward or open position. In addition, or in lieu of the pressure chamber 30, a spring 34 may be utilized actingon the shoulder or piston 32 for biasing the tube 24 upwardly for holding the valve in the open position.

A piston 36 may be provided on the sliding tube 24 and directed upwardly andexposed to pressure exteriorly of the-body 12 through one or more ports 38 and is therefore responsive to pressure in the annulus between the well tubing and the casing. When the pressure exteriorly of the body 12 increases sufficiently, and acts on'the' piston 36, the sliding tube 24 is moved downwardlyaway from the valve seat 20 and disengages from the flapper valve 16 allowing the flapper to move upwardly to the closed position on the valve seat 20 thereby shutting off oil and gas production through the valve and the well tubing. Therefore, when pressure is applied in the annulus between the well tubing and the casing, exteriorly of the body 12 and through the port 38, and against the piston 36, the tube 24 will be moved downwardly closing the valve. This may occur if the well production flowing through the tubing and safety valve 10 escapes from the tubing by leaking through threads in the tubing to the exterior of the safety valve 10 thereby protecting the casing. Or in the event that some other problem occurs in the well, pressure can be increased in the annulus between the tubing and the casing exteriorly of the safety valve 10 to increase the pressure which'is communicated through the ports 38and to the piston 36 for closing the safety valve 10.

I It is to be noted that once the valve closes, the valve 10 is locked in "the closed position and may be reopened only when. the pressure exteriorly of the valve 10 is reduced. The'valve 10 may be suitably reopened and reactivated by suitable wireline operations.

It is to be further noted that a seal 50 is provided on one side of the pressurized chamber 30 and between one side of the chamber 30 and the bore 13 of the tubing. A bleed port is provided leading from between the side of the seal 50 remote from the chamber 30 to exteriorly of the body 12, such as ports 38, so as to be in communication with the pressure exteriorly of the body 12. Similarly, a seal 56 is provided at the lower end of the chamber 30 and between the chamber 30 and the bore l3 and a bleed port 60 is provided on the side of seal 56remote from the chamber 30 leading from the seal 56 to'exteriorly'of the body 12. Therefore, tubing pressure in the bore 13 cannot leak into the chamber 30 to increase the pressure therein and hold the valve in the open position in'the event of a catastrophe. On

tages mentioned as well as others inherent therein. While a presently preferred embodiment of the invention has been given for the purpose of disclosure, numerous changes in the details of construction and arrangement of parts may be provided without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

l. A well safety valve for use in a well tube comprising,

a body having an annular valve seat, valve means for engaging said seat for opening and closing said valve, I a sliding tube telescopically movable in the body positioned below said valve means and movable through the valve for holding the valveopen when the tube is in the upward position and downward movement of the tube closes said valve,

means for biasing said tube upwardly for opening said valve, said biasing means includes a gas chamber, and including,

a seal on each side of the chamber between the chamber and the interior of the tubing, and

a bleed port leading from the side of each seal remote from said chamber and to the exterior of a the body,

piston means connected to the tube, and

passageway means in communication between the piston and exteriorly of the body for moving the I tube downwardly for closing said valve.

2. A well safety valve for use in a well tubing positioned in a well casing comprising,

a body having an annular valve seat, said body including connections for attachment in the well tubmg,

a flapper valve pivotally, connected to the body below the seat and movable upwardly into engagement with the seat for closing the valveandmovable downwardly away from the seat for opening the valve,

a sliding tube telescopically movable in the body and through the seat and positioned below the valve, biasing means for moving the tube upwardly holding the flapper valve away from the seat, said-biasing means includes a gas chamber, and including,

a seal on each side of the chamber and the interiorof the tubing, and a bleed port leading from the side of each seal remote from said chamber seals and to the exterior of the body, upwardly directed piston connected to the tube, passageway means in communication between the piston and the exterior of the body for applying tubing casing annulus pressure on the piston for moving the tube downwardly for closing the valve.

3. A well safety valve for use in a well tubing positioned in a well casing comprising,

a body having an annular valve seat, said body including threaded connections for attachment in the well tubing,

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 positioned below the valve and telescopically movable in the body and through the valve for holding the valve open when the tube is in the upward position and allowing the valve to close when the tube is moved downwardly,

biasing means for yieldably holding the tube upwardly for holding the flapper valve away from the seat,

an upwardly directed piston connected to the tube,

and

passageway means in communication between the piston and the exterior of the body and tubing tube downwardly for closing the valve.

Claims

1. A well safety valve for use in a well tube comprising, a body having an annular valve seat, valve means for engaging said seat for opening and closing said valve, a sliding tube telescopically movable in the body positioned below said valve means and movable through the valve for holding the valve open when the tube is in the upward position and downward movement of the tube closes said valve, means for biasing said tube upwardly for opening said valve, said biasing means includes a gas chamber, and including, a seal on each side of the chamber between the chamber and the interior of the tubing, and a bleed port leading from the side of each seal remote from said chamber and to the exterior of the body, piston means connected to the tube, and passageway means in communication between the piston and exteriorly of the body for moving the tube downwardly for closing said valve.

2. A well safety valve for use in a well tubing positioned in a well casing comprising, a body having an annular valve seat, said body including connections for attachment in the well tubing, 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 telescopically movable in the body and through the seat and positioned below the valve, biasing means for moving the tube upwardly holding the flapper valve away from the seat, said biasing means includes a gas chamber, and including, a seal on each side of the chamber and the interior of the tubing, and a bleed port leading from the side of each seal remote from said chamber seals and to the exterior of the body, upwardly directed piston connected to the tube, passageway means in communication between the piston and the exterior of the body for applying tubing casing annulus pressure on the piston for moving the tube downwardly for closing the valve.

3. A well safety valve for use in a well tubing positioned in a well casing comprising, a body having an annular valve seat, said body including threaded connections for attachment in the well tubing, 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 positioned below the valve and telescopically movable in the body and through the valve for holding the valve open when the tube is in the upward position and allowing the valve to close when the tube is moved downwardly, biasing means for yieldably holding the tube upwardly for holding the flapper valve away from the seat, an upwardly directed piston connected to the tube, and passageway means in communication between the piston and the exterior of the body and tubing whereby a predetermined increase in pressure in the tubing casing annulus on the piston moves the tube downwardly for closing the valve.