US2952268A

US2952268A - Gas lift retrievable valve

Info

Publication number: US2952268A
Application number: US696453A
Authority: US
Inventors: Julius A Blum
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-11-14
Filing date: 1957-11-14
Publication date: 1960-09-13
Anticipated expiration: 1977-09-13

Description

Sept. 13, 1960 Filed Nov. 14, 1957 J. A. BLUM GAS LIFT RETRIEVABLE VALVE 2 Sheets-Sheet 1 (/U/lUJ A. B/um INVENTOR.

ATTORNEY Sept. 13, 1960 L/U/lUJ /l. B/um INVENTOR.

BY \POQ AK. A.w\;m

ATTORNEY United States Patent GAS LIFT RETRIEVABLE VALVE Julius A Blum, Caracas, Venezuela (2444 S. York, Denver 10, C010.)

Filed Nov. 14, 1957, Ser. No. 696,453 '3 Claims. (Cl. 137-155) My present invention relates to a gas lift valve of the type adapted for artificial production of subsurface oil from a well by a method which involves lifting the oil to the surface by gas pressure. It is particularly intended to provide a valve that may be inserted and removed quickly without the expensive operations that normally are necessary for such installation. This application is a continuation-in-part of my co -pending application Serial No. 342,121, filed March 13, 1953, now abandoned.

In the afield of oil production, wells are identified as flowing wells, those Which'flow or gush because of the pressure of gas present therein, or non-flowing wells, those in which the natural gas pressure has become exhausted or reduced to a point where it is insufiicient to lift the liquid to the well head. Various types of artificial production techniques have been developed for use in producing oil from non-flowing wells, one of the more recent of which involves introducing gas under pressure into the annular space between the'internal tubing which contains the liquid and the casing which defines the well, and allowing such gas to enter the tubing at a desired intermediate point to lift the liquid above such point to the surface. Gas lift valves are necessary to regulate the introduction of gas into the tubing, and the present invention is a novel and improved device of this type.

Certain shortcomings of conventional gas lift valves have become apparent. Many of these units have proved to be wasteful of gas, for they allow gas flow to continue beyond the time when there is sufficient liquid present in the tubing to justify its use. Further, in placing such valves, the tubing must be lifted from the well, the valves placed in the proper location and the tubing replaced, an expensive and oftentimes inconvenient series of operations. H

My invention overcomes these objectionable features by providing a valve which is slidable within the tubing. 'A perforation may be made at the desired point in the tubing by well-known surface operated means, or a previously existing opening may be used. My valve includes spaced packing elements which provide seals at each side of the aperture when the unit is positioned generally within the proper area- Gas from the space between the casing and the tubing enters through the perforation and fills the space between the packings from whence it is communicated to a valve operating member which moves in response to various pressures to admit only as much gas to the tubing asis necessary to lift the well liquids upwardly toward the surface. 7

. Accordingly, it is an object of my invention to provide an improved gas lift valve.

M It is a further object of my invention to provide a gas lift valve which may be placed or retrieved from the surface without removing the tubing.

It is a further object of my invention to provide a gas lift valve which may be operatively positioned with only general attention to alignment with a preexisting opening in'th'e tubing.

It is a further object of my invent-ion to provide a gas lift valve having pressure responsive means whereby the most economical use of the lifting gas is made possible.

Other objects and advantages of my invention will be made apparent in the following detailed description studied in conjunction with the accompanying drawings in which:

Fig. 1 is a sectional elevation of a typical producing well with my gas lift valve in place;

Fig. 2 is an enlarged elevation of the central portion of my valve, partly in section, taken substantially on the plane indicated by line 22 of Fig. 1;

Fig. 3 is a cross-section taken substantially on the plane indicated by the line 3-3 of Fig. 2;

Fig. 4 is a cross-section taken substantially on the plane indicated by the line 4-4 of Fig. 2; and

Fig. 5 is a cross-section taken substantially, on the plane indicated by the line 55 of Fig.

In the installation view of my invention shown in Fig. 1, a well casing 1 extends downwardly in a hole drilled into the earth 2. Tubing 3 is located Within the casing 1 in spaced relation thereto, and the casing head 4 seals the tubing 3 in gas-tight relation to the casing 1. A discharge conduit 5 is connected through the casing head 4 to the tubing 3 for delivery of oil and other fluid there from. A gas conduit 6 is connected through the casing head 4 into the annular space 7 between the casing 1 and tubing 3 to introduce therein gas pressure from a suitable source not shown.

The valve unit housing 10 is a composite hollow body, preferably tubular in shape and of such size that it readily slides within the tubing 3. It comprises a lower portion 11, a central portion 12, and an upper portion 13, all of which define an internal conduit 14. The lower portion 11 is closed at the bottomand has a plurality of lateral perforations 15 through the walls thereof so that fluid in the well below the unit may enter the internal conduit 14. A packer or sealing ring 16 is provided about the lower portion 11 above the perforations 15 for contact with the internal walls of the tubing 3. This member preferably is reinforced by a second seal-ing ring '17. These sealing rings are of neoprene or other oil resisting rubber to provide a packer or sealer so that oil or gas may not pass thereby. The central portion 12 contains the working valve which is spaced therein so as not to block ilow upward through the internal conduit 14. The upper portion 13 has an open upper end 18 which allows fluid to re-enter the tubing 3 above the unit housing. Thus the conduit 14 provides a channel of flow from the lower perforations 15 to the upper end 18 while the working valve within the central portion 12 controls the introduction of gas, as will be explained. A second set of

sealing rings

19 and 20 is carried about upper portion 13' to function in a manner similar to the lower sealing rings 16 and 17 and provide a sealed annular chamber 21 between the tubing 3 and the housing 10.

The tubing 3 is provided with one or more lateral ports 22 so that gas under pressure may be communicated from the annular space 7 between the tubing 3 and the casing 1 and into the sealed chamber 21 between the packers '16 and 17, and 119 and 20. The distance between the packing rings provides a margin for error in vertical alignment of the unit within which the aperture 22 may be situated without affecting the operability of the unit Referring now to Figs. 2 through 5, the working valve of the 'unit which is carried within the conduit 14 in the central portion 12 of housing 10 comprises a composite hollow tubular body 23 which is closed at each end. This body is spaced within the housing 10 by external lugs .24 near the top, and external lugs 25 near the bottom.

At an intermediate point along its length are lugs 26 which are internally threaded to receive the attaching bushings 27. Each of the bushings is threadably secured through the walls of the housing to the lugs 26 and is hollow to establish communication between the sealed chamber 21 and the main valve chamber 28 within the body 23. Appropriate check valve means 29 are provided to insure that excessive back pressure in chamber 28 is not communicated to chamber 21. Conventional O-ring seals 30 are included between the bushings 27 and their seats in the housing 10. Thus, passages or ports and

spaces

6, 7, 22, and 27 form, in effect, a continuous conduit for supplying compressed gas to chamber 28 in the valve body.

The main valve chamber 28 is closed at its top by valve seat member 32 which is positioned within the tubular body 23 by any suitable means such as the screw threads 33. A longitudinal conduit 34 extends therethrough into communication with upper valve chamber 35. Wrench apertures 36 are provided in the top of the valve seat member so that it may be removed for repair or replacement by a new member having a larger or smaller conduit opening. The purpose of such replacement will be made apparent in subsequent paragraphs.

Lateral apertures 37 through the wall of the body 23 interconnect the upper valve chamber 35 and the conduit 14. Thus gas from the main valve chamber 28 may join with the well fluids in the internal conduit 14 when the conduit 34 is open.

I prefer to provide a joint in that portion of tubular body 23 which defines the upper valve chamber 35 in order to allow access to the valve seat member 32. This is accomplished in the exemplary embodiment of Fig. 2 by means of mating screw threads 38. Similar interbody joints which are designed to facilitate disassembly and repair are provided at

intermediate points

39 and 40. The plug 41 which closes the bottom of body 23 also is attached by screw threads 42.

Referring particularly to Fig. 2, a valve closure member 43 is designed to operate against valve seat member 32 to open and close the conduit 34 extending therethrough. The closure member has a collar 44 which defines the bottom of valve chamber 28, and an upwardly extending crown 45 which closes conduit 34. The collar has an internal recess 46 at the bottom which mates with the upper end of push rod 47. Thus the closure member 43 is slidable on the push rod within the limits marked by the contact of the crown 45 with valve seat member 32 when the valve is closed, and the contact of the top of the internal recess 46 with the upper end of the push rod 47 when the valve is open. In the embodiment of Fig. 2, the collar is provided with an external resilient member 48 which provides a seal against the internal wall of the main valve chamber 28.

The lower end of push rod 47 is attached to the spring seat and stop member 49 threadedly secured to rod 47. Compression spring 50 acts between the collar 44 and the spring seat member 49 to bias the valve closure member 43 toward an upward or closed position.

Attached to and extending downwardly from the spring .seat member 49 is the extension rod 51, the lower end of which is attached to the bellows 52. The bellows is secured to the plug 41 in the bottom of the tubular body 23 by appropriate means such as a transverse pin 53 acting between mating recesses in the plug. By filling to an appropriate pressure with gas or liquid, the bellows is adapted to provide an upward force on the extension rod 51 and, through member 49 and spring 50, on closure member 43.

An annular guide bearing and stop 54 is formed Within that portion of tubular body 23 which surrounds exten sion rod 51. This member is in close embracing relationship with the extension rod and is provided with an upper .conical seat '55 into which the lower portion of spring 4 seat member 49 is adapted to fit. This serves the purpose of limiting the travel of extension rod 51 and prevents damage to the bellows from an overload in a downward direction on the valve closure member. A packing seal 56 is provided in the stop member 54 to prevent leakage of gas pressure from chamber 28 into the lower portion of the unit where the bellows is housed. This seal is a precautionary measure and supplements the seal 48 about collar 44.

The operation of the combined spring system represented by the coil spring 50 and the bellows 52 is a feature of my invention. When the valve is closed, a portion of the closing force is provided by the coil spring and an approximately equal portion by the bellows. As the valve opens, the valve closure member moves downward on the push rod 47 as the coil spring absorbs its proportionate share of the increased load and the push rod 47, spring seat 49 and extension rod 51 all move downward as the bellows absorbs its share. As the valve opening force increases, the limit of travel of the closure member on the push rod is soon reached at which time the coil spring is precluded from absorbing any additional load. Soon thereafter the spring seat bears against the seat member 55 of the internal stop member 54, and the entire spring system is bottomed out.

The combination of springs guards against a complete valve unit failure in the event of rupture of the bellows or fatigue of the coil spring. Either of the two spring members alone will provide a certain amount of closing force which even though less than that normally provided by both will suflice to close the valve and prevent expenditure of gas without productive eflect. Furthermore, the use of the bellows provides a relatively constant spring which is not subject to the variations with extended use which characterizes a mechanical spring. Therefore such variation will have a relatively smaller efiect on a system which includes a constant unvarying spring member such as the bellows.

I prefer to employ a bellows which has a relatively large spring constant or modulus of elasticity, that is, a large force is required to produce a small increment of movement, and a mechanical spring which has a small spring constant or modulus of elasticity. With such arrangement of parts, the operating stroke of push rod 47 and extension rod 51 will be very small and the extending movement of the spring necessary to effect closure will decrease but a small amount of the total force represented by the compressed spring. This tends to insure substantial opening of the valve upon slight increase in the pressure of gas admitted through port 26 and/ or in the hydrostatic head above the valve. This, in turn, avoids wire drawing eifect and excessive erosion at the valve.

My valve operates in the following manner. The entire unit is positioned inside the tubing 3 with the aperture 22 located between the upper and lower sealing rings 16 and 19. The gas under pressure in annular space 7 enters the sealed chamber 21 through the port 22. It moves through the check valves 29 into the main valve chamber 28 where it is barred from the upper valve chamber 35 by the valve closure member 43 acting against the main valve seat member 32. In the embodiment shown in Fig. 2, the seal 48 about collar 44 confines the gas within the main valve chamber 28 and the gas pressure acts downwardly against the collar of the valve closure member, tending to open the valve conduit 34. The force exerted by this pressure is resisted by the spring system represented by compression spring 50 and. the bellows 52. V

Oil or other fluids from the well will be free to pass through the apertures 15 in the lower portion 11 of the unit and move upwardly through the conduit 14 into the upper tubing through the upper end 18. This fluid will rise to the height in the well dictated by the internal pressure therein. As it moves through the conduit 14,it is free to enter the upper valve chamber 35 through lateral apertures 37. The static head resulting from the weight of the fluid accumulated above the valve in the tubing will be applied to the portion of the crown section 45 of valve closure member 43 which closes the conduit 34. The resulting force will add to the force created by the gas pressure in the main valve chamber 28 tending to move the valve closure member 43' downwardly. Thus, proper design of the springs in the system and the cross sectional area of the conduit 34 coupled with reasonably accurate control of the gas pressure will result in a valve unit which will open only when there is a substantial column of liquids above it. Opening of the valve will allow gas to flow upwardly through the conduit 34 and out of the apertures 37, thereby lifting the well fluids upwardly through the tubing 3 to the top of the well. As soon as the weight of a sufficient portion of the column of liquid has been removed from the crown section 45=by discharge from the top of the well to reduce the static head to a predetermined point, the spring system will again close the valve by moving the valve closure member 43 upwardly.

Proper control of the above-mentioned design features will result in a valve which can be adjusted to meet the demands of various installations and in each case function to release gas only when there is fluid to be moved, thus materially saving in the amount of gas expended. Valve seat member 32. can be readily replaced by a member having a larger or smaller conduit 34 to meet varying installation requirements.

The embodiment illustrated in Fig. 2 is not responsive solely to the weight of the fluid above the unit in the tubing, for the gas pressure also is utilized to provide additional opening force. This obviously necessitates control of the gas pressure in order to design the unit to open in response to an exact. predetermined amount of fluid above the Valve. In certain installations it may be undesirable or troublesome to control the gas pressure closely, in which case certain structural changes will eliminate the effect of the gas pressure on the time of valve opening and result in a unit which is responsive solely to the presence of fluid above it in the tubing.

These changes involve eliminating the seal 48 about the collar 44 and providing lower apertures through the walls of tubular body 23- below the stopmember 54. Thus the gas pressure does not tend to move the valve closure member 43', as it is free to fill the space under the collar 44 and equalize itself. The only opening pressure exerted on the valve will be the weight of the fluid acting on the crown section 45'.

In such case no effort is made to maintain the bellows 52 in a chamber of constant pressure. Instead, the mentioned lower apertures through the body 23 allow the fluid in the conduit 14 to enter and surround the bellows. Obviously the upward force exerted by the bellows at any given moment would be a function of the pressure the bellows and the pressure surrounding the bellows. Therefore, as the weight of the fluid in the tubing above the unit increases, the net force exerted by the bellows on the valve decreases, and the unit may be designed so that a given amount of static head of fluid reduces the force exerted by the bellows to a point where it, combined with the upward force of the coil spring, is equal to the downward force exerted by the same head on the crown section 45 through conduit 34. Any additional head of fluid will open the valve, and it will remain open until the static head has been reduced to a point where the force of the spring system will overcome it to close the valve.

In the suggested modified unit, the seal 56 would prevent the fluid pressure surrounding the bellows from entering the upper part of the housing 23. In all other respects, the operation of the modified valve would be identical to that previously described.

The modified unit would posses certain advantages over the exemplary unit. It is apparent that in the primary embodiment, the

seals

48 and 56 will be subject to leakage after a prolonged period of use. To prevent such leakage from varying the design opening force required, it would be necessary to remove the valve at intervals and relieve any pressures surrounding bellows 52 which had resulted from such leakage. In the modified device, no such internal pressures can build up, and the unit would maintain design characteristics for a longer period of time.

For purposes of illustration, particular embodiments of the invention have been shown and described according to the best present understanding thereof. However, it will be apparent to those skilled in the art that many changes may be made in the construction and arrangement of the parts thereof without departing from the true spirit and purposes of the invention. Accordingly, it is desired to protect by Letters Patent all forms of the invention falling within the scope of the following claims.

The invention having been described, what I claim is:

1. A gas control valve comprising an elongated hollow valve body apertured adjacent one end thereof, a gas supply port communicating with the interior of said valve body intermediate the ends thereof, a valve seat in said valve body between said port and said apertured end of said body, a push rod, a valve element sildably carried on said push rod and cooperable with said seat, a resilient, charged bellows operatively connected to said push rod and reacting against said valve body, to yieldingly urge said valve element toward said seat, an annular guide embracing said push rod between said port and said bellows, a stop member fixed on said push rod and engageable with said guide in response to predetermined yielding of said bellows, and a spring inten-posed between said valve element and said stop member to yieldingly urge said valve element into closing contact with said seat,

2. A gas control valve comprising an elongated hollow valve body having a closed end and an apertured end, a gas supply port communicating with the interior of said valve body intermediate the ends thereof, an annular valve seat in said valve body between said conduit and said apertured end, a valve closure member slidable within said valve body between said port and said closed end, said valve closure member having a crown section extending therefrom adapted to engage said valve seat, a resilient seal between said valve closure member and said valve body, a push rod slidably engaging said valve closure member, stop means limiting the sliding movement of said valve closure member on said push rod, a bellows operatively connected to said push rod and reacting against said valve body adjacent said closed end, a filling of a compressible medium under pressure in said bellows, said compressible medium extending said bellows to yieldingly urge said valve closure member toward said valve seat, an annular guide bearing embracing said push rod between said conduit and said bellows, a sealing ring between said guide bearing and said push rod, a stop member fixed on said push rod, said stop member engaging said guide bearing in response to a predetermined yielding of said bellows, and a spring interposed between said valve closure member and said stop member to yieldingly urge said valve closure member into closing contact with said valve seat.

3. A gas control valve comprising an elongated hollow valve body having a closed end and an apertured end, a gas supply port communicating with the interior of said valve body intermediate the ends thereof, an annular valve seat secured in said valve body between said conduit and saidapertured end, a valve closure member within said valve body adjacent said valve seat, a push rod slidably engaging said valve closure member, stop means limiting the sliding movement of said valve closure member on said push rod, a bellows operatively connected at one end to said push rod and fixed at its 7 other end to said valve body adjacent said closed end; a filling of compressible medium under pressure in said bellows, said compressible medium extending said bellows to yieldingly urge said valve closure member toward said valve seat, an annular guide bearing embracing said push rod between said conduit and said bellows, a sealing ring between said guide bearing and said push rod, apertures through said valve body between said guide bearing and said closed end, a stop member fixed on said push rod, said stop member engaging said guide bearing in response to a predetermined yielding of said bellows, and a spring interposed between said valve clo 8 sure member and said stop'meniber to yieldingly urge said valve closure member into closing contact with said valve seat.

References Cited in the file of this patent UNITED STATES PATENTS 2,070,659 Higham Feb. 16, 1937 2,179,226 Bryan Nov. 7, 1939 2,217,305 Bryan n Oct. 8, 1940 2,248,354 Jaworowsk-i July 8, 1941 2,465,060 Oarlisle et a1. Mar. 22, 1949 2,668,553 7 Howard et a1. Feb. 9, 1954