US2797700A

US2797700A - Balanced flow valve

Info

Publication number: US2797700A
Application number: US372989A
Authority: US
Inventors: Jr Harold E Mcgowen
Original assignee: Camco Inc
Current assignee: Camco Inc
Priority date: 1953-08-07
Filing date: 1953-08-07
Publication date: 1957-07-02
Anticipated expiration: 1974-07-02

Description

,July 2, 1957 H. E. McGowEN, JR 2,797,700

BALANCED FLow VALVE Filed Aug-'7, 1953 2 Sheets-Sheet 1 Haro/Q E. /WCbM/Qn, dr.

INVENTOR.

BY @MM2/mgl H. E. MCGOWEN, JR 2,797,700 BALANCED FLow VALVE July 2, 1957 Filed Aug. 7, 1955 2 Sheets-Sheet 2 w., 6 Wm. n N l il V A 8 4 fm7 r MW. Ml Z f, S 5R@ H 5 2f@ g ,l d L wf /l N. B J5 54N A- uw 111 u A A /f/ ,m ,m

Patented July 2, 1957 pmi BALAN CED FLOW VALVE Harold E. McGowen, Jr., Houston, Tex., assignor to Camco, incorporated, Houston, Tex., a corporation of Texas Application August 7, 1953, Serial No. 372,989

14 Claims. (Cl. 137-155) This invention relates to the application of Huid pressure to accelerate liquid movement such as raising toward the surface of underground oil through a well bore and more particularly to an improved gas lift or flow valve. An oil well bore is usually tted with a large diameter casing within which is positioned a smaller diameter tubing, O

ience, this specification will' treat the tubing as for oil n and the casing for gas, it being understood that as regards the invention the terms may be considered as interchangeable and not as limitations.

It is an object of the present invention to provide an improved pressure responsive valve assembly for controlling flow of pressure gas or fluid from the lift gas supply. passage to the oil column passage and which operates under surface control of gas delivered pressure without regard to oil well pressure fluctuation. To this end theY valve in one embodiment is balanced or has opposed surfaces of equal area exposed to tubing or well pressure and 'is spring loaded on its seat in opposition to application thereon of casing gas pressure whereby the valve will open each timeat the same given gas lift pressure as determined by the preset spring loadto be overcome.

While precise balancing of valve opposed surfaces presented to well pressure is a theoretical optimum for certain installations, it has been found that for most purposes the expense of extreme manufacturing accuracy is not always essential `and satisfactory operation will result if the balancingl surfaces are more or less equal. Furthermore, desirable` effects can be obtained with a selected or intentional slight unbalance, as for example one which favors unseating of the valve by having the total surface area active in opposition to the valve seating spring greater by given amounts as large as eight percent than the total surface area active in valve closing direction. The beneicial result obtained is that well pressure is available to condition the parts for a quick response to surface controlled` gas pressure and` a more instantaneous or snap action in the valve opening operation. Accordingly the balance referred to is one having a slight latitude.

A further object of the invention is to provide -an improved exible wall seal arrangement between the valve and its housing through the use of a pair of spaced bellows, sealing one against casing pressure and another against tubing pressure, with the space or chamber between the bellows containing liquid of a volume substantially filling the bellows chamber when the valve is unseated, whereby the incompressibility of the liquid stablized the exible walls of both bellows and acts as a force transmitting medium between the two bellows walls cation.

and solidly resists or bucks pressure forces imposed on their remote faces exposed respectively to the pressures existing within the tubing and the casing annulus. The casing annulus and tubing interior are in communication whenever the valve is unseated and their pressures will be equalized or approach equalization, wherefore the conlined liquid exerts an equal opposing pressure within the bellows chamber formed between the walls of the bellows and these walls are thus freed from uid pressure deflection stress. In this fashion the bellows walls are protected against casing or gas pressure such as is in excess of valve unseating pressure. They are also protected by another expedient against high tubing or well pressure when the valve is seated and which pressure of itself can never unseat the valve because the pressure force has presented to it opposed surface areas in balanced relation. This latter protective feature is afforded by incorporating solid rings in the convolution spaces on the side of the bellows wall` opposite that exposed to tubing or well pressure, and these rings buck the tubing pressure to resist excess wall deflection laterally without interference to bellows action axially.

Another object of the invention is to provide a gas lift unit whose valve can be unseated only in response to controlled gas pressure and without modification, but by the addition of -a supplemental unit, will afford a variable pressure operation in which unseating of the valve will still be dependent on surface controlled gas lift pressure but a pressure whose value differs according to a predetermined adjustment, and is either lower or higher depending on whether well pressure is above or below a given value. Thus a factor of differential pressures may be introduced for certain installations when desirable, with the primary valve structure being of universal appli- Among other things there will be gained the -economical advantage of larger production with lower unit manufacturing,` inventory, and service costs.

Other objects and advantages become apparent during the course of the following specication having reference to the accompanying drawing illustrating a preferred embodiment and wherein: Fig. l is a vertical sectional view of the improved valve assembly illustrated for ease or` understanding in a somewhat diagrammatic and simplified form; Figs. 2 and 2A are half sectional views of the upper and lower portions of the valve assembly as designed for production usage; Fig. 3 is a fragmentary section illustrating a detail of one of the bellows units, 1and Fig. 4 is a vertical section of the upper portion of a valve having a supplemental spring seating force.

Referring to the simplified illustration in Fig. l the reference character l indicates a hollow tubular valve housing closed at its upper end by a plug 2 and mounted at its lower end on the outside of a mandrel or tubing section 3 for communication through the tube wall with the interior of the well tubing. The location of the valve housing on the outside of the tube is for use of the tube interior for oil tlow. Vvhen oil is to be lifted in the outer casing by supplemental gas pressure supplied by way of the inner tube, the location of the valve housing will be interiorly of the tubing wall. In either event the communication is from one side to the other of the tube wail. In the tube exterior valve arrangement shown, the communicating passage includes one or more wall openings 4 from the annular casing space surrounding the tubing 3, a valve chamber 5 and a passageway 6 leading from the valve chamber to the interior of the tubing mandrel. Located within the valve chamber and seated on an annular shoulder between the chamber 5 and passage 6, is an enlarged head 7 on the lower end of a valve stern 8 slidably mounted within the housing 1 and urged downwardly by a coiled compression spring 9 which bears at opposite ends on a stem abutment 10 and a housing abutment 11,

Below the spring engaging bearing abutment on the stem, the housing has an internal flange or annular rib 12 to the underside of which the upper end of an annular spring metal bellows 13 is secured and. sealed .with its lower end secured and sealedV to an annular collar 14 on the valve stem surrounded by the bellows. Fora balanced valve the internal diameter of the bellows 13 should correspond substantially with the internal diameter of the valve seat at the passage 6. A similar and larger flexible wall or annular bellows 15 is located within thev valve chamber 5 and has its upper end secured and sealed to the housing and its lower end secured and sealed to the rim of the valve head 7 so that the unbalance of valve area exposed to casing fluid favors valve unseating. The annular chamber sealed olf between the two bellows is substantially filled with a liquid of such volume that when the valve 7 is unseated the liquid completely lls the bellowsV chamber and forms in effect a solid strut to resist flexing of the bellows walls inwardly of each other. As a limit stop to preclude excess valve unseating travel, the terminal of the stem 8 is arranged for co-operative abutment with the end plug 2. Permissible Valve travel should be less than that which would impose strain on the bellows seals, including forces which in the absence of a positive stop, would be transmitted through the trapped liquid body.

An open passage 16 extends upwardly through the Valve stem 8 from its lower end to a point above the collar 14 and has one or more side passages or lateral ports 17 leading to the interior of the housing 1 around the upper end of the stern 8 within and above the bellows seal 13. By reason of the passage 16, the interior of the bellows 13 and the upper portion of the housing 1 are in open communication at all times with the tubing interior and will be at a pressure substantially corresponding with tubing or well pressure. Optionally, the passage communicating opposite sides of the valve may be provided through the valve housing wall or by a separate tube, but the formation of the passage 16 in the valve stem is both convenient and economical. In any event, its size can be sufficient to afford free passage and an absence of throttling for a better balancing action during pressure variations. Well pressure will act upwardly against the bottom of valve head 7 exposed to the passage 6 inside the boundary 0f its receiving seat and also against the uppermost surface of the lateral port 17. Likewise it will act downwardly against the lower surface of the port 17 and against the surface of the collar 14 exposed within the bellows 13 and the top end of the stem 8. These oppositely directed surface areas in the aggregate equal or balance one another so that tubing fluid pressure has no effect to move the valve in either direction. By selection of diameter of the port 6 at the valve seat, the valve head area exposed to well pressure can be governed for a desired degree of balance as before indicated.

Operation of the balanced or near balanced valve is independent of variations in well pressure and, even with a slight unbalance, is controlled primarily by the force of the spring 9 in opposition to surface regulated gas lift pressure. The latter acts against the under side of the valve head 7 throughout the exposed surface area beyond the valve seat to the rim of the valve head, with the bellows 15 sealed at its lower end to the top of the valve head 7 limiting the extent of surface exposure to gas lift pressure. Casing pressure is preferably controlled at the surface by suitable valving and when it is desired to implement well pressure for lifting liquid within the tubing, the casing or gas lift pressure is increased to the desired degree and when its force on the valve head overcomes the valve seating force the valve will open. Thereupon and co-incident with well pressure increases, pressure acting on inside face of the bellows 13 and inthe

passages

6 and 16 approximates that on the outside of the bellows 15 in the valve chamber 5. So long as `the valve remains open the casing and well pressure will be the same and the liquid contained within the bellows chamberprotects both bellows and serves as a force transmitting medium between the flexible walls and solidly resists the uid pressure acting with the same force on the outer face of the bellows 15 and on the inner face of the bellows 13. With equalization of pressure on their opposite faces neither of the exible wall seals will be under strain.

At times when the valve is seated and gas lift pressure is low or not needed, there will be occasions when the well pressure acting outwardly on the bellows 13 will rise excessively or surge to a value which might cause breakage of the thin flexible bellows wall if some precaution is not taken to stiften the bellows wall against the high internal force. Thickening of the thin spring metal wall is not feasible, but a satisfactory form of stiiener is shown in Fig. 2 and in the enlarged fragmentary section of Fig. 3. In each of the outer spaces between convolutions there is fitted a solid ller ring 18 of metal or other suitable material, which may be formed in segments for convenience of assembly with the segments either fused together as by welding or held against separation by a circumferential Wire or snap band 19 seated in a peripheral groove in the ring segments. The arrangement enables normal axial deflection but excess well pressure will crowd the inner bends of the convolutions and expand the outer bends with the radial walls bearing firmly against @and restricted from further distention by the fillers 18. By reason of the backing, rupture of the bellows thin wall is unlikely and an effective bucking of high well pressures is provided.

Since it would not be practical to build the housing and the stem each in one piece, after the fashion diagramed in Fig. l, a production embodiment will involve an assembly of parts joined together as in Figs. 2 and 2A. Here it will be seen that both the housing and valve stems are shown as threaded together parts and the joints are sealed against leakage by either solder or suitable packing rings or both.

The housing spring seat 11 is an externally threaded ring adjustably mounted in the upper sleeve portion of the housing 1. Upon removal of the end plug 2, the ring 11 may be threaded in or out in order to preset the elastic force of the spring 9 for the response to a calculated value of gas pressure. Usually a number of llow valves will be employed at different levels on the well tubing and each can be individually set at a different pressure unseating value so that surface control will enable selective introduction at several levels of lift force to the uid to be lifted, which for example may consist 0f oil or a mixture of oil and gas.

Fig. 2 also shows a pair of closure plugs 20 and 21 in the housing side wall for closing vent and ller openings leading through the wall to the chamber formed between the bellows. For some purposes a single opening may constitute a combined filler and vent port. After assembly of the embodiment shown, liquid is introduced through the port in which the plug 21 is later tted and venting occurs through the opening later closed by the plug 20. In the lling operation the chamber space is substantially filled with the liquid and at least to the extent that a slight collapse of the bellows incident to the unseating of the valve will ll a void intentionally provided. Should an increase in volume be necessary within the bellows to allow valve opening, it will be at the expense of space withinthe valve chamber 5 by bulging of the wall of the bellows 15. However, the latter is expected to be negligible, since the filling operation can be so controlled that the liquid body volume allows opening of the valve before the entrapped liquid stops valve travel and is conditioned to neutralize pressures acting outwardly on the bellows 13 and inwardly on the bellows 15.

Inasmuch as deep well temperatures often exceed by several times earth surface temperatures, it will be preferable to employ a high boiling point bellows entrapped liquid having a relatively low co-eicient of expansion for the heat encountered and thus minimize disturbances to the pre-selected Valve opening pressure.

When it is desired to supplement the force of the main spring, 9 and modify operation of the valve in accordance with well pressure values, the end plug Z is removed and the upper end of the housing 1 is extended as in Fig. 4 to inclose a retractible plunger 22 arranged to bear at its lower end on the upper terminal of the valve stern S and to be slidably mountedy at its upper end in a closure plug 23. A coil spring 24 bears at opposite ends on the plug 23 and a

collar

2,5 adjustably threaded on the lower end of the plunger 22; The adjustable mounting of the spring seating collar 25 enables any desired given loading for the spring 24. A sealing bellows 26 surrounds the plunger and is sealed at opposite ends to the cap plug 23 and to a collar or shoulder on the plunger 22. Thus the bellows 26 limits plunger area exposed to well pressure to cause plunger retraction when the iluid presure reaches the value of the force exerted by the` spring 24.. Such. Huid pressure will tend to take the spring 24 out.` ofV action, in proportion to the value of the fluid pressure and when the WellV pressure is high the mainv valve will open ata relatively lower lift gas pressure than. isrequired when, wellpressure is low.

A plug 2'7 closes the end. of a central opening in the cap 23 which slidably receives the upper terminal of plunger 22 as a sub-assembly with the cap. Throughout its major extent the opening is circular and at its lower end is oblong or elliptical, providing diametrically opposite `inwardly extending lands for slidable bearing with a reduced

neck

2,8 on the plunger. Beyond the neck, the plunger has an enlarged head 29 also of oblong shape to aord a T-shaped terminal which may be alined with, and passed through the oblong opening or key hole slot and then turned ninety degrees for retention. The shoulders at opposite ends of the reduced lower portion of the central opening afford limit stops for the head at one end of the reduced plunger neck and a shoulder at the other end, the axial length of the neck being greater than that of the reduced diameter passage in accord with the desired range of travel.

While but one embodiment of the invention is herein disclosed, it will be understood that various modifications may be made as come within the scope of the appended claims.

What is claimed is:

l. In a gas lift valve, a housing having an inlet and an outlet and a passage for communicating the inlet and the outlet, a spring seated pressure actuated valve controlling pressure uid flow through said passage, a pair of spaced flexible wall seals between the housing and the movable valve, said lseals being joined to the valve to present substantially balanced opposed valve areas t the outlet pressure and unbalanced valve areas favoring valve unseating to the `inlet pressure, one of the wall seals sealing the valve and housing with respect to inlet pressure and the other wall seal sealing the valve and housing with respect to outlet pressure and a substantially incompressible liquid contained in the space between said walls and of a volume conforming to the volume of said space when the valve is open to serve as a force transmitting medium in equalizing forces on opposite faces of cach flexible wall.

2. In a gas lift valve, a housing having a fluid flow passage, a spring seated valve in the housing, a bellows sealing the valve to the said passage and co-operating with the valve to define an area exposed to fluid pressure on one side of the valve for adding a valve seating force in counteracting balance in relation to other valve area exposed to said liuid pressure in opposition to the valve seating spring and a second bellows sealing the valve to the housing so that a valve area is exposed to uid pressure on the other side of the valve for unseating the valve.

3. In a gas lift valve assembly of the character described, a housingv anda spring seated valve therein, opposed surfaces on the valveA exposed to one source of fluid pressure insubstantially balanced relation, a bellows sealing the valve and housing with respect to said pressure source, a valve area exposed to a second source of fluid pressure for unseating the valve and a bellows sealing the valve toA the housing withV respect to said second pressure source.

4.`In a gas lift valve assembly of the character described, aV housing and a spring seated valve therein, approximately equalV opposed surface areas on the valve exposed to fluid pressure on one side of the valve, a bellows seal between the valve and the housing againstescape of said pressure, a Valve area exposed to fluid pressure on the opposite side of the valve for unseating the valve, a bellows seal between the valve and the housing against blow by of the last mentioned uid pressure, and a body of liquid of a volumelling the space between said bellows seals when the valve is unseated.

5. In a well flow valve primarily responsive to surface controlled fluid pressurev on the inlet side of the valve without major regard to uctuations inpressure on the outlet side of the valve, a spring seated valve having approxirnately'balanced4 opposed areas exposed to the last mentionedfpressure anda differential `area exposed to the inletl Huid pressure to open the valve, double bellows seals for the valve and la body of liquid confined between the seals and of a volume to afford a stii stru-t between the seals when the valve is open.

6. The structure of claim 5 together with solid rings in the spaces between the convolutions on the liquid side of the bellows which seals against the said last mentioned pressure.

7. In a well flow valve assembly, a spring seated valve having a surface exposed to fluid pressure on the upstream side of the valve in unseating the valve, a bellows seal to exclude said pressure from action on an opposing valve surface, a second bellows seal effecting an approximate balance of opposed surfaces exposed to fluid pressure on the downstream side of said valve and solid fillers in the spaces between convolutions of the second lbellows on `the side opposite to that subject to the last mentioned pressure.

8. In a well flow valve assembly responsive to pressure of the uid whose flow is to be controlled, a spring seated valve presenting more or less balanced opposing surfaces to fluid pressure on the downstream side of the valve and unbalanced surfaces to fluid pressure upstream of the valve, a pair of spaced sealing bellows respectively sealing against pressure iluid upstream of the valve and pressure fluid downstream of the valve, solid llers between outer convolutions of the bellows seal against pressure on the downstream side of the valve to resist outward pressure force on said bellows convolutions, and a liquid -body between the bellows which iills the intervening space when the valve is open to resist bellows wall deflection under iluid pressure on the upstream side of the valve.

9. In a well gas lift valve assembly for imposing supplernental pressure on existing well pressure, a housing having a lift gas passage therethrough, a spring seated valve controlling said passage, a surface area exposed to the pressure of incoming lift gas in the housing upstream of the valve for unseating the Valve, a secondary spring exerting a seating force on the valve and a bearing for the secondary spring having unbalanced surfaces exposed to uid pressure on the downstream side of the valve to control the force exerted by said second spring in proportion to increase in the last mentioned Huid pressure.

l0. In a gas lift valve of the character described, a housing having a fluid flow passage and a Valve seat in the passage, a valve engageable with the seat, -a pair of springs separately exerting forces to seat the valve, a bellows seal between the valve and the housing serving to confine the valve surface area exposed to fluid pressure 7 ahead of the Valve in favor of unseating the valve and a movable abutment for one of said springs, in separable engagement with said valve land subject to fluid pressure beyond said valve in opposing spring force thereon and tending to move said `abutment away from engagement with the valve.

ll. In a gas lift valve of the character described, a housing having a passage, a valve seat in the passage, a valve engageable with said seat, 1a pair of springs exerting forces to seat the valve, a bellows seal between the valve and the housing, there being a valve surface area exposed to pressure in advance of the valve for unseating the valve, a plunger retractably mounted in said housing in response to fluid pressure beyond the valve, a bellows seal between the plunger and the housing and an abutment on the plunger to act on one of said springs land decrease the force exerted thereby upon plunger retraction.

12. A one way valve assembly including a passage to communicate two sources of pressure iluid, a valve seat in said passage, a Valve slidably mounted -to engage said seat, a bellows seal (zo-operating with the valve, yieldable force exerting means urging the valve toward its seat, a surface on the valve exposed on one side of said `bellows seal to one of said pressure fluid sources 4for unseating the valve when the pressure on said surface overcomes said yieldable force exerting means and opposed surfaces of equivalent elective area on the valve fully exposed on the other side of said bellows wall and Without restriction at all times to the other source of fluid pressure.

13. In a valve assembly of the character described, a housing, a movable pressure responsive valve in the housing, a ilexible wall sealing the movable valve -to the housing against pressure uid ahead of the valve a second llexible wall spaced from the rst wall to seal the Valve and housing against pressure uid behind the valve, and an incompressible liquid conned in the space between said walls and of a volume to fill the space when the pressure responsive valve is lifted from its seat.

14. The structure of claim 13 wherein said flexible walls are of the bellows type and solid rings are disposed within the convolution spaces onthe liquid side of one of the bellows to resist bellows lateral deection under uid pressure thereon in excess of uid pressure on the other bellows,

References Cited in the file of this patent UNITED STATES PATENTS 647,706 Robertshaw Apr. 17, 1900 862,867 Eggleston Aug. 6, 1907 2,086,295 Ernst July 6, 1937 2,385,316 Walton Sept. 18, 1945 2,647,015 Berlyn July 28, 1953 2,670,683 Lundh Mar. 2, 1954 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,797,700 July 2, 1957 Harold E. McGowan, Jr.

It is hereby certified that error appears .in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 66y for nthe housing" read the said passageline 67, for "said passage" read housing-u.

Signed and sealed this 20th day of August 1957.

SEAL) ttest:

KARL H. MEINE ROBERT C. WATSON bbestng Officer Comnssioner of Patents