US3887005A

US3887005A - Storm choke

Info

Publication number: US3887005A
Application number: US294745A
Authority: US
Inventors: Gary W Rosenwald
Original assignee: Cities Service Oil Co
Current assignee: Cities Service Oil Co
Priority date: 1972-10-03
Filing date: 1972-10-03
Publication date: 1975-06-03
Anticipated expiration: 1992-06-03

Abstract

Accidental blow out of a producing oil or gas well is prevented by means of two normally open, self-closing valves located one above the other in the production tubing of the well. The first valve has a disc which automatically engages and mates with a seat when mechanical tension normally applied to the disc is released. The second valve has a disc which automatically engages and mates with a seat when hydraulic pressure normally applied to the disc is released. Flow of petroleum fluid through the production tubing can be shut off by closing either or both of the valves. Use of two valves actuated by different mechanisms provides greater assurance of positive shut off during an emergency.

Description

United States Patent Rosenwald June 3, 1975 1 STORM CHOKE Primary Examiner-H. Hampton Hunter [75] Inventor: Gary W. Rosenwald, Tulsa, Okla. Agent or F'rmEh0n [73] Assignee: Service Oil Company, Tulsa. {57] ABSTRACT Accidental blow out of a producing oil or gas well is [22] filed: I972 prevented by means of two normally open, self-closing 2 App]. 294 745 valves located one above the other in the production tubing of the well. The first valve has a disc which automatically engages and mates with a seat when me- [52] US. Cl.2 166/72; 166/224 R chanical tension normally applied to disc is [5]] [ISL Cl. F28Dol/06 leased The Secund valve h a disc which automati [58] held of Search 166/72 224 S cally engages and mates with a seat when hydraulic pressure normally applied to the disc is released. Flow Reierences cued of petroleum fluid through the production tubing can UNITED STATES PATENTS be shut off by closing either or both of the valves. Use 2,963,089 l2/l960 Sizer 166/72 of two valves actuated by different mechanisms pro- 3,288,22l ll/l966 Howard et al. l66/72 X vides greater assurance of positive shut off during an 3,310,!14 3/l967 Dollison 166/72 X emergency 3,791,445 2/1974 True l66/72 15 Claims, 2 Drawlng Figures llllllllll STORM CHOKE BACKGROUND OF THE INVENTION Due to fire and health hazards, the potential loss of produced fluids, and potential damage to the environment, there has been increased emphasis on use of downhole safety shut-off valves, e.g., storm chokes, for flowing petroleum wells. By means of a storm choke, the flow of petroleum fluids through the production tubing of a flowing well can be shut off in an emergency, thus providing means for preventing or controlling an accidental blow out.

Most of the storm chokes now used are of three basic types which are installed in the well bore:

1. A valve which automatically closes and thus shuts off flow of fluid when the pressure differential across the valve becomes too great. More specifically, a valve of this type is designed to shut automatically if the flow of fluid through it exceeds a certain limit.

2. A hydraulically activated valve to which hydraulic fluid is pumped from the surface when an emergency arises.

3. A valve through which the fluid will flow only if the pressure in the well bore at the valve is above a pressure at which the valve is preset to close and which closes automatically if the pressure falls below the preset value.

None of the valve arrangements mentioned above has proven to be altogether satisfactory because of total dependence upon fully automatic operating systems which sometimes fail or else because it has not always been possible to complete an action at the surface which is necessary for opening or closing the valve.

It is therefore an object of the present invention to provide a simple and reliable storm choke system comprising two valves which can be secured in a normally open condition and which will close automatically upon manual or accidental release of a securing means for holding the valves open. Other objects and advantages of the invention will become apparent from the following description which is, of course, intended to be illustrative rather than limitative.

SUMMARY OF THE INVENTION The present invention resides in apparatus for com trolling flow of petroleum fluids through the production tubing of a flowing well. Two valves, or chokes, are located within the production tubing, one valve being positioned above the other. Each valve is normally open but is self-closing upon release of a force which holds it open. One valve is held open by a mechanical tension applied to the disc thereof whereas the other valve is held open by a hydraulic pressure applied to the disc. Separate operating means continuously urge the disc of each valve towards engagement with its respective seat, so that either valve becomes closed when the overriding force which holds it open is released.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a somewhat diagrammatical sectional view of a producing well having one embodiment of the apparatus of the present invention installed therein.

P16. 2 is a sectional view of a storm choke in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS In HO. 1, a production well generally indicated at l has a string of production tubing 2 which extends from above the surface of the earth 3 through a casing 4 to a petroleum producing reservoir 5.

A storm choke comprising a dual valving mechanism, generally represented at 6, is located within the production tubing between the surface and the producing reservoir and will be described later in greater detail with reference to FIG. 2. The choke comprises upper and lower valve seats represented at 7 and 8 respectively, and upper and lower valve discs, represented at 9 and 10 respectively, which can engage and mate with the seats. The upper disc is equipped with an attached valve stem 11 which is connected at the lower end to an upper piston 12. The lower disc also has an attached valve stem 13 which is connected at the upper end to a lower piston 14. Each piston is axially aligned within a cylinder 15 disposed axially within the production tubing 2 and attached to the inner wall thereof by means of brackets 16. By means of upper and lower compressed springs, represented at 17 and 18 respectively, each piston is continuously urged downward, hence, continuously urging the

discs

9 and 10 toward engagement with their

respective seats

7 and 8.

It is desired that both valves of the choke be in a normally open condition for production through the well and means are thus required for overcoming the tension of the

springs

17 and 18 so that the discs are normally held off the seats. With the choke shown in FIG. 1 this is accomplished by applying mechanical tension in an upward direction against the disc 9 while applying hydraulic pressure to the bottom of the lower piston 14 so that the disc 10 is raised off seat 8. Both the mechanical tension and the hydraulic pressure for securing the valves open can be effected by means of a hollow, flexible hydraulic line 19 which extends from the upper disc 9 upward through the production tubing 2 and out of the top of the tubing through a bushing 20. The hydraulic line 19 is wrapped around the reel of a wench 21 for applying tension to the line so that disc 9 can be held off the seat 7. Engagement and mating of the disc 9 with the seat is accomplished by backing off on the wench so that piston 12 can be moved downward by means of spring 17. Disc 9 will also automatically engage seat 7 in the event that the hydraulic line 19 becomes accidentally broken by damage or destruction of the production tubing 2 and/or platform 22.

The lower valve of the choke is held open by pumping hydraulic fluid into the lower end of cylinder 15 so that piston 14 is displaced upward, thus raising disc 10 off seat 8 and compressing spring 18. By means of the spring tension being exerted against the upper end of piston, the disc 10 is continuously being urged to move into engagement with the seat 8, but this force is overridden by the application of hydraulic pressure to the lower end of the cylinder 15. Closing of the lower valve is thus accomplished by deliberate or inadvertant relief of the hydraulic pressure within the cylinder.

Pressurized hydraulic fluid is supplied to the cylinder through the hollow, flexible hydraulic line 19. The lower end of the hydraulic line is firmly attached to the disc 9, and the hollow interior of the line communicates with a channel which extends all the way through the disc 9, stem 11 and piston 12. An auxiliary hydraulic line 23 extends from the channel in the upper valve mechanism to the lower chamber 37 of the cylinder, thus providing a path for fluid from the surface to the lower valve of the choke. Pressurization of hydraulic fluid in line 19 is effected by means of a pump 24 located in the line. The fluid pressure is regulated by means of a shunt line 25 having a flow control valve 26 whereby part of the fluid delivery from the pump is returned to a fluid reservoir 30 via the shunt, i.e., the pressure increases as the amount of shunted fluid is reduced and vice versa. A guage 27 can be employed in line 19 for determining the pressure therein and thus providing means for ascertaining whether sufflcient pressure is being supplied for holding the valve open. Once the desired pressure is reached in line 19, valve 28 can be closed to hold the pressure in the line. Should the pressure gradually fall off, it can be reestablished by reopening valve 28 and repeating the pumping procedure. Pressurization can also be maintained by means of an automatic detector-controller device. As previously indicated, the lower valve will close automatically when the hydraulic pressure in the lower chamber 37 of the cylinder falls or is reduced below a value which overrides the tension of spring 18. For quick closure of the lower choke valve in an emergency, relief valve 29 is opened to achieve a rapid bleed-down of pressure in line 19 and chamber 37. As previously indicated, the lower choke valve will close automatically should line 19 become broken in a storm, fire or other accident.

It will also be appreciated that a flexible hydraulic line such as 19 can be run down the production tubing independently of a separate cable attached to disc 9 and wench 21, thus providing a stouter means for pulling up on the disc with the wench and lessening the possibility of accidentally parting the hydraulic line when manipulating the disc. For convenience, the hydraulic line can be wrapped around that part of the cable which extends below the pulley 42 and into production tubing 2. As an alternative, a stout tubing or pipe can be run from below the pulley down to the upper valve disc, thus serving as both a mechanical linkage and a conduit for hydraulic fluid. In such a case, a cable could be attached to the upper end of the pipe and extended over to the wench, with hydraulic fluid being pumped into the pipe at a point between the pulley 42 and seal 20.

During operation of a system as shown in FIG. 1, both the upper and lower valves are held open by means of mechanical tension and hydraulic pressure, respectively. Petroleum fluid flows upward through both valves and is recovered at the surface through line 31. In an emergency one or both valves can be closed by tripping the wench 21 and/or by opening relief valve 29. Both valves close automatically upon accidental breakage of the hydraulic line 19. Use of two valves in the choke provides greater assurance that flow of fluids can be shut off in an emergency. If both valves function properly the production tubing can be doubly plugged, and one valve should continue to function in the event that the other fails.

Both valves of the choke can be easily tested at any time to determine the operability thereof. The upper valve is checked by backing off on the wench, whereas the lower valve is checked by opening the hydraulic relief valve 29. Closure of the valves during a test is ascertained by determining that flow of produced fluid has been interrupted in line 31.

FIG. 2 illustrates a storm choke which operates in the same manner as that shown in FIG. 1 except that closure of the valves is effected by expansion of a compressed fluid instead of a spring. Each end of the cylinder I5 is closed by means of upper and

lower plates

32 and 33 which are provided with

seals

34 and 35 through which stems I] and 13 extend from the

pistons

12 and 14 to the

discs

9 and 10. The pistons and the inner wall of the cylinder are honed for a close fit for the sealing of fluid in upper and lower

expansible chambers

36 and 37 between the pistons and the end plates. The pistons can also be provided with O-rings for an even closer fit with the cylinder wall.

The flexible, hydraulic line 19 is attached to the top of disc 9 through upper stem 11 but the hollow interior of the line communicates with a channel 38 in the stem which extends all the way through the disc 9, the stem 11 and piston 12. An auxiliary flexible, hydraulic line 23 extends from the bottom of the upper piston 12 to the expansible chamber 37 at the lower end of cylinder 14 and provides means for conveying hydraulic fluid from line 19 into chamber 37 without restricting movement of the upper piston.

A sealed bellows 39 is contained in the cylinder above the lower piston 14. The bellows contains a compressed fluid such as air, nitrogen, an inert gas or the like. The top of the bellows abuts a rigid plate 40 in the cylinder and the bottom of the bellows rests upon the upper surface of piston 14. The length of the bellows and the pressure of the fluid therein are such that they will expand and result in seating of the disc 10 and seat 8 when the hydraulic pressure in chamber 37 is insufficient to offset the expansion. Otherwise, the hydraulic pressure overrides expansion of the bellows so that disc 10 is held off the seat 8. It will be appreciated that the bellows could be dispensed with and the compressed fluid contained within the space between piston 14 and plate 40, but a bellows is preferred since it is a more assured means of maintaining the compressed fluid under pressure without leakage.

As illustrated in FIG. 2 a compressed fluid such as nitrogen, air or the like is contained in chamber 36 by means of the wall of the cylinder 15, the piston 12, end closure 32, stem 11 and the stem seal 34. Accordingly, the gas pressure in chamber 36 is sufficient to displace piston 12 downward when there is no upward tension on line 19, thus urging the disc 9 into engagement with seat 7. However, this pressure is normally overridden by tension on the line so that the gas is further compressed in chamber 36 while holding disc 9 off of the seat. Where preferred, a sealed bellows such as 39 can be employed in chamber 36 for containing the compressed fluid, or compressed springs can be used in either chamber for urging the pistons as shown in FIG. 1. In addition, the hydraulic fluid in chamber 37 could also be contained in a sealed bellows interconnected with line 23.

In FIG. 2, the discs for the valves are located above their respective seats, but it will be apparent that either one orboth of the discs could be located below the seats and urged in an upward direction for automatic closure of the valves. In such a case the upper valve could be secured open hydraulically while the lower valve is held open mechnically. Reversal of the hydraulic securing means to the upper valve and the mechanical securing means to the lower valve could also be employed with the choke of FIG. 2 wherein the valve discs are located above the seats.

In addition, the sealing surfaces of the discs and seats do not have to be beveled as shown since other sealing arrangements could also be used, e.g., flat surfaces or engagement of a seal ring with a matching groove. Where preferred. gussets 41 can be attached between the wall of the production tubing 2 and the

seats

7 and 8 to provide a more rigid construction.

The present invention has been described with reference to particular apparatus features and arrangements thereof but it will be understood that still other em bodiments will become apparent which are within the spirit and scope of the invention defined by the following claims.

What is claimed is:

1. In a producing well having a production tubing which extends below the surface to a producing reservoir. apparatus for controlling flow of fluid through the production tubing which comprises:

a. upper and lower valve seats, each located within the production tubing,

b. operable upper and lower valve discs, each located within the production tubing and adapted to respectively engage and mate with the upper and lower seats when operated,

c. separate operating means for continuously urging each valve disc toward engagement with its respective seat.

d. mechanical means for selectively securing the upper valve discs in a position off of its seat and for releasing the upper disc for movement by its respective operating means, and

e. hydraulic means for securing the other valve lower disc in a position off of its seat and for releasing the disc for movement by its respective operating means.

2. Apparatus as in claim 1 wherein the means for urging at least one of the valve discs to move toward its respective seat comprises a tensioned spring.

3. Apparatus as in claim 1 wherein the means for urging at least one of the valve discs to move toward its respective seat comprises a compressed fluid.

4. Apparatus as in claim 1 wherein the mechanical means for securing and releasing the valve disc comprises a mechanical linkage attached to the disc and which extends up through the production tubing and is adapted for movement within the tubing, and further comprising means at the surface for selectively securing and moving the mechanical linkage within the tubmg.

5. Apparatus as in claim 4 wherein the mechanical linkage comprises a conduit along the length thereof and further comprising means at the surface for pumping hydraulic fluid into said conduit and for controlling hydraulic pressure in said securing and release means for the lower valve disc.

6. Apparatus as in claim 1 wherein the hydraulic means for securing and releasing one of the valve discs comprises a cylinder secured to the inner wall of the production tubing, a piston in the cylinder, the piston being attached to the valve disc, a fluidconveying tubing which leads from the cylinder and up through the production tubing and further comprising means at the surface for pumping hydraulic fluid into the cylinder through the conveying tubing and for controlling fluid pressure in the cylinder.

7. Apparatus as in claim 2 wherein the spring is compressed when the valve disc is disengaged from the valve seat.

8. Apparatus as in claim 1 wherein the operating means for continuously urging at least one of the valve discs toward engagement with its respective seat comprises a sealed but expansible chamber for 21 contained fluid, the chamber being located within the production tubing and secured to the wall thereof, fluid within the chamber being relatively compressed when the valve disc is secured from engagement with its seat and relatively expanded when released and engaged therewith.

9. Apparatus as in claim 8 wherein the sealed but expansible chamber is a bellows.

10. Apparatus as in claim 8 wherein the sealed but expansible chamber is a cylinder having a fitted piston therein, the cylinder being axially aligned with the valve disc and the piston being attached to the disc.

11. A valve comprising:

a. upper and lower valve seats,

b. operable upper and lower valve discs, adapted to respectively engage and mate with the upper and lower seats when operated,

c. separate operating means for continuously urging each valve disc toward engagement with its respective seat,

d. mechanical means for selectively securing the upper valve disc in a position off of its seat and for releasing the upper disc for movement by its respective operating means, and

e. hydraulic means for securing the lower valve disc in a position off of its seat and for releasing the lower disc for movement by its respective operating means.

12. In a producing well having a production tubing which extends below the surface to a producing reservoir, apparatus for controlling flow of fluid through the production tubing which comprises:

a. a first self-closing valve in the production tubing which has a valve disc and a matching valve seat which are coaxially aligned within said tubing, the valve disc of said first valve being biased toward engagement with its seat, but wherein said first valve is normally held open by a mechanical tension applied to the disc thereof in a direction opposite from that in which the disc is biased, and whereupon release of said tension the disc of the first valve is urged into contact with its seat, hence closing the first valve, and

b. a second self-closing valve in the production tubing which has a valve disc and a matching valve seat which are coaxially aligned within said tubing, the valve disc of the said second valve being biased in a direction toward engagement with its seat, but wherein said second valve is normally held open by a hydraulic pressure applied to the disc thereof in a direction opposite from that in which the disc is biased, and whereupon release of said pressure the disc of the lower valve is urged into contact with its seat, hence closing the second valve.

13. Apparatus as in claim 12 wherein the first valve is an upper valve and the second valve is a lower valve.

14. Apparatus as in claim 13 wherein the discs of the respective valves are located below their seats.

15. Apparatus as in claim 14 wherein the discs of both valves are biased in a downward direction toward engagement with their respective seats.

Claims

1. In a producing well having a production tubing which extends below the surface to a producing reservoir, apparatus for controlling flow of fluid through the production tubing which comprises: a. upper and lower valve seats, each located within the production tubing, b. operable upper and lower valve discs, each located within the production tubing and adapted to respectively engage and mate with the upper and lower seats when operated, c. separate operating means for continuously urging each valve disc toward engagemEnt with its respective seat, d. mechanical means for selectively securing the upper valve discs in a position off of its seat and for releasing the upper disc for movement by its respective operating means, and e. hydraulic means for securing the other valve lower disc in a position off of its seat and for releasing the disc for movement by its respective operating means.

4. Apparatus as in claim 1 wherein the mechanical means for securing and releasing the valve disc comprises a mechanical linkage attached to the disc and which extends up through the production tubing and is adapted for movement within the tubing, and further comprising means at the surface for selectively securing and moving the mechanical linkage within the tubing.

8. Apparatus as in claim 1 wherein the operating means for continuously urging at least one of the valve discs toward engagement with its respective seat comprises a sealed but expansible chamber for a contained fluid, the chamber being located within the production tubing and secured to the wall thereof, fluid within the chamber being relatively compressed when the valve disc is secured from engagement with its seat and relatively expanded when released and engaged therewith.

11. A valve comprising: a. upper and lower valve seats, b. operable upper and lower valve discs, adapted to respectively engage and mate with the upper and lower seats when operated, c. separate operating means for continuously urging each valve disc toward engagement with its respective seat, d. mechanical means for selectively securing the upper valve disc in a position off of its seat and for releasing the upper disc for movement by its respective operating means, and e. hydraulic means for securing the lower valve disc in a position off of its seat and for releasing the lower disc for movement by its respective operating means.

12. In a producing well having a production tubing which extends below the surface to a producing reservoir, apparatus for controlling flow of fluid through the production tubing which comprises: a. a first self-closing valve in the production tubing which has a valve disc and a matching valve seat which are coaxially aligned within said tubing, the valve disc of said first valve being biased toward engagement with its seat, but wherein said first valve is normally held open by a mechanical tension applied to the disc thereof in a direction opposite from that in whiCh the disc is biased, and whereupon release of said tension the disc of the first valve is urged into contact with its seat, hence closing the first valve, and b. a second self-closing valve in the production tubing which has a valve disc and a matching valve seat which are coaxially aligned within said tubing, the valve disc of the said second valve being biased in a direction toward engagement with its seat, but wherein said second valve is normally held open by a hydraulic pressure applied to the disc thereof in a direction opposite from that in which the disc is biased, and whereupon release of said pressure the disc of the lower valve is urged into contact with its seat, hence closing the second valve.