US3433174A

US3433174A - Subsurface well intermitter

Info

Publication number: US3433174A
Authority: US
Inventors: David V Chenoweth
Original assignee: Baker Oil Tools Inc
Current assignee: Baker Hughes Oilfield Operations LLC
Priority date: 1967-01-13
Filing date: 1967-01-13
Publication date: 1969-03-18
Anticipated expiration: 1986-03-18

Description

March 18, 1969 D. V. CHENOWETH SUBSURFACE WELL INTERMITTER Filed Jan. 13, 1967 Sheet NVENTQB. V: CHE/v0 WE n( March 18, 1969 D. v. CHENOWETH 3,433,174

SUBSURFACE WELL INTERMITTER Filed Jan. 13, 1967 Sheet 2 of I; 2. lm. 2Q. Ew- 3f T/* I w l; L

a QN@ Q9@ ,DAV/D V CHENOWETH ma/ul D. V. CHENOWETH SUBSURFACE WELL INTERMITTER Mgrch 18, 1969 Filed Jam.A 14s, 1967 .260 3o Sheet L? INVENTOR ,DAV/D V. CHENOWETH #fram/Ex United States Patent Olce 3 ,433,1 74 Patented Mar. 18, 1969 3,433,174 SUBSURFACE WELL INTERMITTER David V. Chenoweth, Houston, Tex., assignor to Baker Oil Tools, Inc., Commerce, Calif., a corporation of California Filed Jan. 13, 1967, Ser. No. 609,028

U.S. Cl. 10S-232 22 Claims Int. Cl. F04f 1/20; F16k 31/145, 3.7/365 ABSTRACT 0F THE DISCLOSURE A subsurface intermitter for lifting oil or water from -gas wells, or high gas/oil ratio wells, and embodying a gravity valve for maintaining the liquid level in the well within a range of several feet by controlling the flow of liquid into a tubing string in the well bore under the action of the gas pressure, and also embodying a longitudinally disposed, laterally operative differential gas lift valve that opens when the liquid level in the tubing string reaches a predetermined level to admit the gas pressure to the tubin-g string for lifting the liquid therein to the surface of the well.

The lpresent invention relates to a downhole intermitter that utilizes the gas pressure in a well for intermittently lifting water, oil or other liquid in the well to the surface. The invention is more particularly directed to a gravity valve, to a gas lift valve, and to a combination of such gravity and gas lift valves, and more specifically to a combination of such valves that can be lowered throu-gh a tubing string on a wire line to a desired location therewithin, and also removed from the tubing string on a wire line.

It has been proposed to keep gas wells dewatered by automatically diverting the Water, or other Well liquid, including oil, into a tubing string disposed in the well as it accumulates in the well bore, thereby maintaining a minimum liquid level in the well casing and the hydrostatic head of liquid acting against the gas producing formation at a low level. A gravity valve has been used for controlling the passage of water, oil, or other liquid, into the tubing string under the pressure of the gas in the well casing, and a differential gas lift valve has been employed for lifting the well liquids through the tubing string to the top of the well bore. With such equipment, a low and substantially constant fluid level is maintained in the well bore, the gravity valve preventing the gas from entering the tubing string, which is only allowed to enter the tubing string for the purpose of lifting the liquid in the tubing string after it has risen to a predetermined level.

Prior equipment of the nature above indicated required at least partial incorporation of the equipment in the tubing string, making it necessary to remove the entire tubing string from the well bore in the event any parts required replacement or repair. In addition, gravity valves heretofore used were cumbersome and relatively complex, providing one of the reasons for the inability to retrieve the entire gravity valve through the tubing string.

The gas lift valves previously used were mounted in the tubing string separate and apart from the gravity valve. If retrievable on a wire line, a separate trip was required, which is time consuming and costly.

With applicants invention, the gravity valve is relatively simple and can be made of small transverse dimensions, enabling it to be run in a tubing string and retrieved therefrom on a wire line. Despite its comparatively small lateral or transverse dimensions, it can still exert substantial force, preventing the liquid in the well bore from passing into the tubing string until the liquid level rises to substantially a predetermined level, after which the gravity valve opens to permit the gas pressure in the well bore to force the liquid up through the gravity valve and into the tubing string.

The gravity valve is connected to a differential gas lift valve having a `straight-through passage, and which, in turn, is connected to a lock assembly, this entire combination being capable of 'being run into and removed from a tubing string by means of a wire line, and being locked in place at a desired location in the tubing string, in which the lower portion of the gravity valve will always be immersed in the water, oil, or other liquid in the well bore. When the liquid level in the well bore rises to a certain level, the gravity valve will open and the gas pressure in the tubing-casing annulus will force the liquid up through the gravity valve and through a hollow mandrel of the differential gas lift valve, and through the lock assembly into the tubing string thereabove. When the liquid level rises to substantially a predetermined extent within the tubing string, it triggers and opens the gas lift valve. so that the gas under pressure in the tubing-casing annulus can enter the gas lift valve and lift the liquid in the tubing string thereabove to the surface of the well bore. When the liquid in the tubing string has been unloaded suiciently, the gas pressure closes the differential -gas lift valve. When the liquid level in the casing string surroundin-g the gravity valve drops to a certain level, the gravity valve is automatically closed, until the formation produces additional liquid and deposits it in the casing string. When this liquid level rises to a predetermined value, the gravity valve again reopens automatically to again permit the gas pressure to drive the liquid up through the gravity valve and the gas lift valve into the tubing string thereabove.

Accordingly, it is an object of the present invention to provide a gravity valve, gas lift valve, and lock assembly combination that can be lowered in a tubing string as a unit on a wire line, and which can also be easily removed as a unit on a wire line.

Another object of the invention is to provide a gravity valve that can maintain the liquid level in the well bore at a comparatively low level, and which will automatically divert the well liquids into the tubing string when they -accumulate to a certain extent, the gravity valve being of a compact and comparatively simple construction, and yet capable of exerting a substantial 4valve closing force when the level of the uid in the well bore drops to a predetermined value.

A further object of the invention is to provide a gravity valve capable of developing and exerting a considerable force for the purpose of closing the Valve n response to a hydrostatic water or other liquid differential of a comparatively few feet.

Yet another object of the invention is to provide a gas lift valve having a hollow mandrel that allows the fluid passing upwardly through it to follow a straight-line path, and which also permits the gas lift valve to be made of relatively small transverse dimensions, so as to be movable through a tubing st-ring, the gas lift valve normally being maintained in a closed position by the -gas pressure in the tubing-casing annulus, and being shiftable to an open position automatically as a result of the liquid level in the tubing string rising above the gas lift valve to a predetermined height.

This invention possesses many other advantages, and has other objects which may be made more clearly apparentf rom a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE l is a diagrammatic view, partially sectional and partially in elevation, of a well intermitter system for producing both gas and liquids from a well bore;

FIGS. 2, 2a and 2b together constitute a longitudinal section through the gas lift valve and gravity valve disposed in a tubing string, both the gravity valve and the gas lift valve being in closed positions, FIGS. 2a and 2b being lower continuations -of FIGS. 2 and 2a, respectively;

FIGS. 3, 3a and 3b are views corresponding to FIGS. 2, 2a and 2b, showing the gravity valve and the gas lift valve in open conditions, FIGS. 3a and 3b being lower continuations of FIGS. 3 and 3a, respectively;

FIG. 4 is an enlarged cross-section taken along the line 4 4 on FIG. 2b;

FIG. 5 is an enlarged cross-section taken along the line 5 5 on FIG. 2b;

`FIG. 6 is an enlarged cross-section taken along the line 6-6 on FIG. 2b.

The invention is typically applicable to a gas well which is producing some water. It is desired to hold the water level in the well bore to a low value, to reduce the back pressure against the gas producing formation F to offer minimum resistance to the flow of gas into the well bore. As disclosed digrammatically in FIG. l, a well casing C is disposed in a well bore, which has perforations 10 opposite the gas producing formation or zone F. A tubing string T extends into the well casing from the top of the Well bore, through which it is desired to produce or lift the water, `or other liquid, in the well casing to the surface, the liquid and some gas passing through a master valve 11 at the top of the hole and then through a branch line 12 to a suitable tank or pit (not shown), the flow of fluid through the branch line being controlled by a suitable valve 13. The gas passes upwardly through the tubing-casing annulus A to the top of the well bore and then through a gas line 14 for distribution to a desired location. An equalizing line 15 extends between the tubing string T above the master valve 11 and the gas line 14, which is controlled by a valve 16 that will normally be closed, this equalizing line being used for equalizing the pressure within the tubing string and casing string when desired.

The liquid in the casing string C is maintained at a low level, which preferably is below the elevation of the casing perforations 10, the liquid being produced through the tubing string T. The passage of liquid into the tubing string is controlled yby a gravity valve B disposed within the lower end of the tubing string T, the liquid passing upwardly through a differential gas lift valve D and through a lock assembly E into the tubing string T above the latter. The lock assembly, differential gas lift valve, and gravity valve can be lowered as a unit from the top of the well bore through the tubing string to a desired location in the lower portion of the tubing string, as determined by engagement of the body 17 of the lock assembly with a companion shoulder 18 in a seating nipple 19 forming part of the tubing string, the lock assembly including latches 20 that can expand outwardly into a companion circumferential locking groove 21 in the seating nipple, to prevent inadvertent upward movement of the lock assembly E, gas lift valve D, and gravity valve B within the tubing string, after the apparatus has been landed therewithin. The lock assembly carries a suitable side seal 22 sealing against the inner wall 23 of the seating nipple to prevent any fluids, either gas or liquid, from passing between the lock assembly and the seating nipple and into the tubing string. The lock assembly has a suitable fishing head 24 at its upper portion for lowering the equipment, which includes the lock assembly, differential gas lift valve and gravity valve, in the well casing on a wire line (not shown) through the tubing string, and for releasing the lock assembly E from the seating nipple 19 through retraction of its latches 20 and for elevating the combination of equipment through the tubing string to the top of the well bore. The lock assembly per se forms no .part of the present invention and can be of any known type. As an example, it may be of the type illustrated in United States Patent No. 2,885,- 007.

The tubing string T below the seating nipple 19 has a section provided with perforations 25 to permit the gas under pressure in the well casing to enter the interior of the tubing string. The gravity valve has its lower portion disposed in the liquid in the well casing, and will always retain the level of the liquid in the well casing below the upper portion of the gravity valve, as described hereinbelow. The gas under pressure in the casing string C can enter through the production tube section below the nipple 19 and ow into the gas lift valve D, when permitted to do so, for the purpose of lifting a slug of liquid, that has been permitted to enter the tubing string T through the gravity valve B and gas lift valve D, to the top of the well bore for discharge into the line 12 leading to the tank or a suitable pit (not shown).

The gravity valve is illustrated specifically in FIGS. 2a, 2b, 3a, 3b, 4, 5 and 6. It includes an outer housing formed of a number of sections, including an upper head 31 threadedly secured to a coupling 32, which is, in turn, threadedly attached to a tubular connection 33 of the differential gas lift valve D, disclosed in FIGS. 2 and 3. The upper head 31 is secured, as by a Weld 34, to an upper reservoir section 35 of the housing, the lower end of which is secured, as 'by means of a weld 36, to an intermediate head 37 threadedly secured to a lower housing section 38 depending therefrom, this lower housing section having its lower portion surrounding a lower head 39 to which it is secured in any suitable manner, as by means of a weld 40.

An inlet screen 41 is threadedly secured to the lower end of the lower head 39 and has slots 42 therein through which the water or other liquid in the well casing can enter. Preferably, the lower end of the screen is closed by a plug 43, or the like. The liquid flows through the screen to its interior and then into the lower head 39, flowing through a longitudinal passage 44 therein into the intermediate housing section 38. The liquid, when the gravity valve B is in its open condition, can also iiow from the passage 44 through a choke or bean 45 suitably secured to the lower end of a cantilever tube 46 extending upwardly through the intermediate housing section 38, through the intermediate he'ad 37, and through the upper reservoir section 35, the upper end of this tube being piloted within the upper head 31 to which it is secured, as by means of a weld 47. The tube is also secured to the intermediate head 37 by a weld 48. The tube is free to flex laterally below the intermediate head 37, and when moved to the left, as seen in FIGS. 2b and 3b, it is in its open position, the orifice or choke passage 49 through the choke member moving from a closed position against a tungsten carbide valve seat 50 (FIG. 2b) to a position in which the orifice 49 is to one side of the seat (FIG. 3b).

The tungsten carbide seat 50 is suitably secured to a stem 51 slidable longitudinally in a passage 52 formed in the lower head 39. The lower end of a helical compression spring 53 bears against a spring seat 54 threadedly mounted in the passage 52, the upper end of the spring 53 engaging a square cross-sectional upper portion 55 of the stem to urge the carbide seat 50 against the lower end of the choke 45 and hold it slidably in engagement therewith. The cantilever tube 46 is preliminarly detiected, so as normally to occupy a position to one side of the seat 50, as determined by its engagement with a stop 56 provided on the upper portion of the lower head, and in which the orifice 49 through the choke is in open condition, as disclosed in FIG. 3b. When the cantilever tube is deliected in the opposite direction, or

to the right, as seen in FIGS. 2b and 3b, it engages an opposite stop portion 57 on the lower head 39, which will retain the choke in the position in which its orice 49 is closed by the seat, as shown in FIG. 2b. The lower end of the cantilever tube 46 is guided in its deflecting or swinging movement by the opposed sides 58 of an elongate opening 59 formed in the upper portion of the lower head, the opposed stops 56, 57 dening the ends of this opening.

The cantilever tube inherently tends to occupy an open condition, as disclosed in FIG. 3b, having spring-like characteristics to shift itself back toward the stop 56. It is deflectable by a differential hydrostatic head of liquid present in an elongate diaphragm 60, which is in the form of an elastomer tube, disposed within the intermediate portion 38 of the housing and extending substantially from the intermediate head 37 to the lower head 39. The lower end 61 of this tube 60, which may have a generally semicircular cross-section, as disclosed in FIG. 4, so that its curved portion 60a snugly engages the wall of the intermediate housing section 38, is closed and is secured to the lower portion of the cantilever tube 46 above its choke 45 by a suitable clamp 62. The upper end of the tube 60 is secured to a nipple 63 threaded into the intermediate head 37, this nipple communicating with a reservoir tube 64 piloted within a head passage 65 and extending thereabove into the reservoir portion 35 of the housing. Liquid, such as water, can be placed in the reservoir 35 and tube 60 through perforations or slots 66 in the upper part of the reservoir, this liquid lling the tube 60, nipple 63, reservoir tube 64, and the housing 35 up to the level of the perforations 66, and providing a hydrostatic head of liquid tending to expand or inflate the diaphragm or elastomer tube 60. One side 60h of the diaphragm bears against a metallic diaphragm strip 67, which engages the cantilever tube 46.

In a typical installation, the liquid level in the casing C will be at a lower level than the perforations or slots 66, and such level will vary as a result of the operation of the apparatus. Generally speaking, it will never rise to the level of the perforations 66. A hydrostatic head of fluid will be exerted by the liquid within the diaphragm or tube 60, tending to expand the latter and shift the cantilever tube 46 laterally to one side, in which the choke or valve head 45 is disposed in its closed position, as illustrated in FIG. 2b. As the liquid level in the casing C rises, such level also rises within the lower portion of the gravity valve, the liquid passing through the slots 42 and lower head passage 44 into the intermediate housing section 38 and around the exterior of the elastomer tube 60, there being a differential between the hydrostatic head acting on the liquid within the elastomer tube 60 and the hydrostatic head acting on the exterior of the diaphragm tube 60. When the liquid level in the casing string C and around the exterior of the diaphragm tube 60 drops suticiently, the ditterential pressure within the diaphragm tube is sucient to deect the cantilever tube 46 from its normal position, in which its orifice 49 is open (FIG. 3b), to the closed position, as disclosed in FIG. 2b. As the liquid level in the casing C and around the diaphragm tube 60 increases, the diiferential pressure within the diaphragm tube decreases, until the inherent spring force of the cantilever tube 46, tending to shift its choke or valve head 45 to the open position, overcomes the differential pressure within the diaphragm tube, the cantilever tube then springing back or returning to its normal or open position, as disclosed in FIG. 3b.

By way of example, let it be assumed that the height of the water column acting within the diaphragm 60 from the perforations 66 to the lower end of the diaphragm tube is about 80 inches. This is equivalent to a unit pressure at the lower end of the diaphragm tube 60 of a little less than 3.5 p.s.i. Assuming the diaphragm tube to have a length of about 40 inches, the average hydrostatic head within the mid-portion of the diaphragm would be about 2 p.s.i. Assuming the metallic diaphragm strip to be 36 inches long and about 13/3 inches wide, the average outward force exerted against the strip would be about 100 lbs., and this total force is acting in a lateral direction against the cantilever tube 46, tending to deflect it toward its closed position, or to the position shown in FIG. 2b. As stated above, the hydrostatic head of the liquid externally of the diaphragm tube 60 is offsetting this force. When the external liquid level drops sufficiently, there is sufficient differential force available within the tube 60 to shift the cantilever tube 46 to its closed position. The force acting against the cantilever tube, by virtue of the differential hydrostatic head within the diaphragm tube, is being exerted at an average point substantially below the lower end of the intermediate head 37, which, by way of example, would be about 20', inches below the intermediate head, providing a substantial lever arm for the applied hydrostatic differential pressure force.

With the arrangement illustrated, in which the elongate diaphragm or elastomer tube 60 is employed, a considerable force can be created for deecting the cantilever tube 46 `to a closed position with a few feet of water or other liquid in the diaphragm tube furnishing the hydrostatic head differential. This longitudinal diaphragm allows the outside diameter of the entire gravity valve B to be made sufficiently small as to be retrievable in its entirety through the tubing string T. If a greater hydrostatic liquid dilferential were deemed necessary to actuate the gravity valve toward its closed position, then all that need be done is to provide an elastomeric tube 60 of a greater length, or provide a cantilever tube y46 of greater length, or both, which would not require any increase in the outside diameter of the gravity valve.

When the gravity valve is opened, the gas under pres sure in the tubing-casing annulus A above the level of the liquid acts upon the liquid and forces it through the slots 42 to the interior of the screen 41 and up through the passage 44 and the open orifice 49 into the cantilever tube passage 70, the fluid flowing from the upper end of this passage into the gas lift valve D. This gas lift valve includes an outer housing or valve body 71, consisting of the lower tubular connection 33 threadedly secured to the coupling 32, the upper end of which is threadedly attached to an intermediate housing section 72, the upper end of which is, in turn, threadedly secured to an upper housing connector or head 73 secured to a sub 74. This sub may be connected directly or through an intermediate nipple (not shown) to the body 17 of the lock assembly E. Accordingly, the lock assembly E is secured to the differential gas lift valve D, the latter being secured to the gravity valve B, the entire combination being movable as a unit through the tubing string T.

The gas lift valve D has a valve seat 75 in its upper portion which may be clamped between an upwardly facing shoulder 76 of the upper housing head 73 and a downwardly facing shoulder 77 on the sub. A valve head ring 78 is clamped against a hollow mandrel 79, extending within substantially the entire length of the outer housing or valve body 71, by a retainer screw 79h having a head S0 engaging the valve ring and forcing it against a mandrel shoulder 81. The mandrel 79 is slidable within a pas' sage 82 in the upper housing connector 73, making a slip t therewithin. Its lower portion 83 is slidable longitudinally within a lower housing head 84 suitably clamped within the housing by its upper end engaging a downwardly facing housing shoulder 85, being held thereagainst by the upper end of the lower housing connector 33. A side seal ring 86 on the lower head 84 engages the inner wall of the intermediate housing section 72, and a side seal 87 is also mounted in the interior of the lower head 84, slidably engaging the periphery of the mandrel stem 83 extending within the lower head passage 88.

The mandrel 79 and its valve head ring 78 are urged toward a downward position by a helical compression spring 89, the upper end of which bears against the lower end of the upper connector or head 73, and the lower end of which bears against a spring seat 90 in the form of a nut adjustably threaded on the mandrel 79, a lock nut 91 also being threaded on the mandrel to bear against the adjusting nut and secure it in its adjusted position. The seal diameter R of the valve head ring 78 against the valve seat 75 is greater than the seal diameter S of the lower head seal 87 against the mandrel stem 83, providing a differential area over which the gas under pressure within the casing C above the liquid level in the casing can act, this gas under pressure passing to the interior of the housing 71 and around the mandrel 79 through housing ports 92 located immediately above the lower head 84.

When the mandrel 79 is in its upper position to engage the valve head ring 78 with its companion valve seat 75, gas under pressure cannot flow into the tubing string T above the gas lift valve D. When the mandrel 79 is shifted downwardly to disengage the valve head ring 78 from its seat 75, gas under pressure can then ow from the exterior of the housing 71 through one or a plurality of orifice discs 93 mounted in the upper connector 73 to an interior chamber 94 in the latter, the gas under pressure then passing around the valve head ring 78 and through the valve seat 75 to the passage 95 through the sub 74 thereabove, this gas under pressure lifting the liquid in the tubing string thereabove to the top of the well bore and discharging it through the line 12 to the tank or pit.

The valve D is shifted to an open position when the hydrostatic head of liquid in the tubing string T above the mandrel 79 reaches a level exerting sufficient downward force on the mandrel, which, when coupled with the downward force exerted by the spring 89, overcomes the total force exerted by the gas under pressure within the housing 71 and acting in an upward direction over the mandrel across the differential area provided by the difference in diameters between the seal diameter AR of the valve head ring 78 against the valve seat 75 and the seal diameter of the lower seal 87 against the periphery of the mandrel. Thus, a rise in the liquid level within the tubing string T to a predetermined value automatically effects opening of the gas lift valve D, allowing the gas under pressure owing through the orifice disc 93 to lift the liquid through the tubing T to the top of the well bore. When the pressure above the mandrel 79 decreases sufficiently, the gas under pressure in the casing string C and within the spring chamber 71 surrounding the mandrel is sufficient to overcome the force of the spring 89 and the force of the gas in the tubing string T above the mandrel to reclose the gas lift valve; whereupon liquid will again be forced upwardly through the gravity valve B, assuming it to be in its open condition, and through the central passage 79a through the mandrel of the gas lift valve into the tubing string thereabove.

In the use of the apparatus illustrated in the drawings, the combination of the lock assembly E, differential gas lift valve D, and gravity valve B is lowered as a unit on a wire line in the tubing string T, the mechanism passing through the seating nipple 19 to the desired location in the casing string, with the lock assembly E coming to rest upon the shoulder 18, whereupon the latches 20 will snap into the locking groove 21. The wire line and running-in tool (not shown) can then be released, in a known manner, from the lock assembly E. Prior to lowering the apparatus, water or other suitable liquid is placed within the reservoir 35, filling the elastomeric diaphragm tube 60, the nipple 63, and reservoir tube 64, and the reservoir housing portion up to the level of the perforations or slots 66. The hydrostatic head within the diaphragm will then exert a maximum force, deflecting the cantilever or springlike tube 46 to its closed position, as illustrated in FIG. 2b.

The gas under pressure is flowing from the formation F through the perforations into the tubing-casing annulus A, and is constantly present therewithin. However,

such gas is prevented from entering the gravity valve B through its screen 41, since the liquid level is always maintained several feet above the inlet screen. Assuming the liquid level has risen in the casing C `and within the gravity valve B around the exterior of the diaphragm 60 to a suicient height, the differential hydrostatic pressure tending to expand the diaphragm l60 and hold the cantilever tube 46 in its closed position will decrease, the inherent spring-like characteristics in the cantilever tube being such as to cause it to return to its normal position in which the gravity valve is opened; that is, the 'valve head has been shifted to the left, as seen in FIGS. 2b and 3b, to the open condition illustrated in FIGS. 3, 3b. The gas under pressure in the casing string is then effective to force the liquid through the slots 42 of the screen 41, up through the passage 44, and through the orifice 49 in the valve head into the cantilever tube 46, this liquid then moving upwardly through the mandrel passage 79a of the differential gas lift valve, which is then in a closed position as disclosed in FIG. 2, the liquid level rising in the tubing string T above the gas lift valve. As described above, the gas under pressure is also being exerted through the housing ports 92 upon the mandrel 79, tending to hold it in the closed position. When the level of the liquid, such as water, in the tubing string rises sufficiently, the hydrostatic head of the liquid acting downwardly on the mandrel 79 supplements the force of the spring 89 to overcome the gas pressure tending to hold the mandrel in its upward or closed position, the mandrel 79 then being shifted or snapped downwardly to the opened condition illustrated in FIG. 3; whereupon the gas pressure can pass through the orifice 93 into the chamber 94, and around the open valve head 78, to lift the liquid in the tubing string T, expelling the liquid rat the top of the well bore into a tank or pit, which is at atmospheric Ipressure. As the liquid is unloaded at the top of the Well bore, the gas that has passed through the orifice 93 accelerates, the gas pressure within the tubing string T above the mandrel 79 dropping. When it decreases sufficiently, the gas pressure within the housing 71 acting in an upward direction over the differential area R-S of the mandrel, is again sufficient to shift the mandrel 79 upwardly against the force of the spring 89 and to its closed condition.

When the liquid level in the casing string C drops suiciently around the diaphragm 60, the hydrostatic pressure differential within the diaphragm `60 increases suiciently to exert a lateral force through the diaphragm strip 67 upon the cantilever tube 46, to again deflect and shift it laterally to its closed position, in which the tungsten carbide seat again closes the orifice 49 through the valve head 45. This closed condition will remain until suicient liquid again flows from the formation F through the perforations 10 into the casing string C and drops downwardly thereof. When the level of liquid rises sufficiently, the external hydrostatic pressure acting on the diaphragm will again rise or increase to offset the internal hydrostatic pressure, until the differential pressure available is insuflicient to overcome the spring force of the cantilever tube 46, which then inherently shifts to the left, as seen in FIGS. 2b and 3b, against its stop 56, in which its orifice 49 is again open. The gas pressure in the tubing-casing annulus A is again effective to force the liquid upwardly through the orifice -49 and the cantilever tube 46 into the gas lift valve D, passing upwardly through the straight-through mandrel passage 79a into the tubing string T thereabove. When the liquid level in the tu'bing string T again rises sufficiently, the gas lift valve D is again opened by snapping the mandrel 79 downwardly t0 its valve opening position, permitting the gas under pressure to again lift the water or other liquid in the tubing st ring T Kand discharging it at the surface into the tank or plt.

The foregoing cycle of operation of the opening and closing of the gravity Valve B, and of the opening and closing of the gas lift valve D, occurs periodically to insure the retention of the liquid level in the casing C at a low value, so that it does not impose any back pressure on the formation F. The lower portion of the gravity valve B, to a level above its valve head 45, is always immersed in liquid so that virtually no gas is present in the gravity valve around the diaphragm 60. If some gas does become entrapped in the liquid, it can vent outwardly of the housing 38 through one or more vents 38a that may ybe 'provided in the upper portion of the housing. The only gas used is that employed for lifting the liquid through the tubing string T to the top of the well bore, and this gas is recoverable at the top of the hole.

The combination of the lock assembly E, differential gas lift valve D, and gravity valve B can be installed or retrieved under pressure by means of a wire line, without pulling the tubing string T from the well casing. The gravity valve B can exert a substantial closing force on its cantilever tube 46, the transverse dimension or outside diameter of the gravity valve being kept to a low figure, which enables it to ibe installed or retrieved through the tubing string on a wire line, or the like. The entire apparatus is completely automatic in operation, being dependent upon the influx of the well liquid through the gravity valve B and the gas lift valve D into the tubing string T. It is unnecessary to undertake any manual operation, or control the operation of equipment by means of a surface timer, or the like. The liquid flows upwardly through longitudinal passages in the gravity valve and the gas lift valve through comparatively straight-line paths, which minimizes the possibility of trash lockup, or other plugging, of the equipment yby foreign material that may be entrained in the liquid.

I claim:

1. In a flow device adapted for use in a tubular string disposed in a well bore for controlling flow of well bore fluid into the tubular string: a first longitudinally disposed valve member having a flow passage; a second longitudininally disposed valve member engageable with said first member to close said passage and prevent fluid flow therethrough; one of said members being shiftable laterally of said other member to open and close passage; and elongate means having a longitudinal axis and being communicable with and responsive to the hydrostatic head of fluid in the well bore for shifting said one of said members laterally of said other member, said shifting means axis extending along said one of said members, said shifting means being constructed and arranged to Shift said one of said members laterally of said other member in response to said hydrostatic head of fluid.

2. In a flow device as defined in claim 1; wherein said shifting means extends along and shifts said first valve member laterally of said second valve member.

3. In a flow device adapted for use in a tubular string disposed in a well bore for controlling flow of well bore fluid into the tubular string: a rst valve member having a flow passage; a second valve member engageable with said first member to close said passage; one of said members being shiftable laterally of said other member to determine the opened and closed conditions of said passage; and means responsive to the hydrostatic head of fluid in the well bore for shifting said one of said members laterally of said other member; wherein said first valve member comprises an elongate tube; said shifting means engaging said tube to deflect said tube laterally of said second valve member.

4. In a flow device as defined in claim 1; wherein said first valve member comprises an elongate tube.

5. In a flow device adapted for use in a tubular string disposed in a well bore for controlling flow of well bore fluid into the tubular string: a first valve member having a flow passage; a second valve member engageable with said rst member to close said passage; one of said members being shiftable laterally of said other member to determine the opened and closed conditions of said passage; and means communicable with and responsive to the hydrostatic head of fluid in the well bore for shifting said one of said members laterally of said other member, said shifting means extending along said one of said members and being constructed and arranged to be shifted laterally of said other member in response to such hydrostatic head of fluid; wherein said shifting means comprises diaphragm means having a substantially constant hydrostatic head of fluid acting thereon and tending to shift both said diaphragm means and said one of said members laterally of said other member, said diaphragm means also being subject to the hydrostatic head of fluid in the well bore to provide a force on said diaphragm means opposing the force thereon provided by said substantially constant hydrostatic head of fluid.

6. In a flow device as defined in claim 5; wherein said diaphragm means and first valve member are shifted laterally of said second valve member.

7. In a flow device adapted for use in a tubular string disposed in a well bore for controlling flow of well bore fluid into the tubular string: a first valve member having a flow passage; a second valve member engageable with said first member to close said passage; one of said members being shiftable laterally of said other member to determine the opened and closed conditions of said passage; and means responsive to the hydrostatic head of fluid in the well bore for shifting said one of said members laterally of said other member; wherein said first valve member comprises an elongate tube; said shifting means comprising diaphragm means having a substantially constant hydrostatic head of fluid acting thereon and tending to deflect said tube laterally of said second valve member, said diaphragm means also being subject to the hydrostatic head of fluid in the well bore to provide a force on said diaphragm means opposing the force thereon provided by said substantially constant hydrostatic head of fluid.

8. In a flow device adapted for use in a tubular string disposed in a well bore for controlling flow of well bore fluid into the tubular string: a first valve member having a flow passage; a second valve member engageable with said first member to close said passage; one of said members being shiftable laterally of said other member to determine the opened and closed conditions of said passage; and means responsive to the hydrostatic head of fluid in the well bore for shifting said one of said members laterally of said other member; wherein said shifting means comprises an elongate tubular elastomer diaphragm having a longitudinal axis and having a substantaially constant hydrostatic head of fluid acting therein and tending to shift said diaphragm laterally of its axis to shift said one of said members laterally of said other member, said diaphragm also being subject to the hydrostatic head of uid in the well bore acting externally on said diaphragm to provide an external force on said diaphragm opposing the internal force therein provided by said substantially constant hydrostatic head of fluid.

9. In a flow device as defined in claim 8; wherein said diaphragm acts on and shifts said first valve member laterally of said second valve member.

10. In a flow device adapted for use in a tubular string disposed in a well bore for controlling flow of well bore fluid into the tubular string: a first valve member having a flow passage; a second valve member engageable with said first member to close said passages; one of said members being shiftable laterally of said other member to determine the opened and closed conditions of said passage; and means communicable -with and responsive to the hydrostatic head of fluid -in the well bore for shifting said one of said members laterally of said other member, said shifting means extending along said one of said members and being constructed and arranged to be shifted laterally of said other member in response to such hydrostatic head of fluid; wherein said first valve member comprises an elongate tube; said shifting means engaging said tube and comprising an elongate tubular elastomer diaphram having a longitudinal axis and having a substantially constant hydrostatic head of fluid acting therein and tending to shift said diaphragm laterally of its axis to shift said tube laterally of said second valve member, said diaphragm also being subject to the hydrostatic head of fluid in the well -bore acting externally of said diaphragm to provide an external force on said diaphragm opposing the internal force therein provided by said substantially constant hydrostatic head of fluid.

11. In a iiow device adapted for use in a tubular string disposed in a well bore for controlling flow of well bore iluid into the tubular string: a first valve member having a flow passage; a second valve member engageable -with said iirst member to close said passage; means for shifting one of said members relative to said other member to determine the opened and closed conditions of said passage, said shifting means comprising an elongate longitudinally extending diaphragm having a longitudinal axis and having `a substantially constant hydrostatic head of fluid acting thereon and tending to shift said diaphragm laterally of its axis to shift said one of said members relative to said other member, said diaphragm also being subject to the hydrostatic head of uid in the well bore to provide a force on said diaphragm opposing the force thereon provided by said substantially constant hydrostatic head of uid.

12. In a flow device as delined in claim 11; wherein said diaphragm comprises an elastomer tube, said substantially constant hydrostatic head of uid acting internally of said tube, said hydrostatic head of iluid in the well bore acting externally on said tube.

13. In a flow device adapted for use in a tubular string disposed in a well bore: a valve body having a valve seat; a mandrel in said body and having a longitudinal passage therethrough; upper and lower means on said body supporting said mandrel for longitudinal movement in said body into and from engagement Awith said seat; said -body having orice means therein between said seat and said upper means and through which fluid externally of said body can ow into the tubular string when said mandrel is disengaged from said seat; said lower means sealingly engaging said mandrel; means engaging said mandrel for shifting said mandrel from said seat; said body having a passage between said upper and lower means through which fluid externally of said body can pass for action on said mandrel to urge said mandrel into engagement with said seat to close said orifice means.

14. In a flow device as deiined in claim 13; the seal diameter of said seat against said mandrel being greater than the seal diameter of said lower means against said mandrel.

15. In a ow device as defined in claim 13; said upper 0 body being elongate with its valve seat in its upper portion, said mandrel passage being constantly open, the upper portion of said mandrel engaging said seat to close said orice against ow of uid therethrough and through said seat, said upper means being spaced below said seat, said shifting means shifting said mandrel downwardly from said seat, the fluid passing through said .body passage urging said mandrel upwardly into engagement with said seat.

1,7. In a flow device adapted for use in a tubular string disposed in a well bore for controlling .flow of Well bore fluid into and through the tubular string: a lower gravity valve adapted to be disposed inthe tubular string and having a flow passage therein and valve means controlling iiow of well bore liquid into said passage in response to the hydrostatic head of such liquid in the well bore; and a gas lift valve adapted to be disposed in the tubular string above said gravity valve and connected to said gravity valve, said gas lift valve having a passage through which the liquid passing through said gravity valve passage can flow into the tubular string above the gas lift valve, said gas lift valve having valve means responsive to the liquid level in the tubular string for -controlling flow of gas under pressure into the tubular string to lift the liquid therein.

18. In a flow device as defined in claim 17 said gravity valve and gas lift valve being constructed and arranged for movement as a unit through the tubular string between the top of the well bore and a desired location therein; and means connected to said gas lift valve for releasably securing said gas lift valve and gravity valve to the tubular string at such desired location.

19. In a ow device as dened in claim 17; said valve means of said gravity valve comprising a rst valve member having a flow passage, a second valve member engageable with said first member to close said passage, one of said members being shiftable laterally of said other member to determine the opened and closed conditions of said passage, and means responsive to the hydrostatic head of fluid in the 'well bore for shifting said one of said members laterally of said other member; said valve means of said gas lift valve comprising a valve body having a valve seat, a mandrel in said body and having a longitudinal passage therethrough, upper and lower means on said body supporting said mandrel for longitudinal movement in said body into and from engagement with said seat, said body having oriice means therein between said seat and said upper means through which fluid externally of said body can flow when said mandrel is disengaged from said seat, said lower means sealingly engaging said mandrel, means engaging said mandrel for shifting said mandrel from said seat, said body having a passage between said upper and lower means through which uid externally of said body can pass for action on said mandrel to urge said mandrel into engagement with said seat to close said orifice means.

20. In a flow device as defined in claim 17; said valve means of said gravity valve comprising a first valve member having a flow passage, a second valve member engageable with said rst member to close said passage, one of said members being shiftable laterally of said other member to determine the opened and closed conditions of said passage, and means responsive -to the hydrostatic head of fluid in the well bore for shifting said one of said members laterally of said other member; said valve means of said gas lift valve comprising a valve body having a valve seat, a mandrel in said body and having a longitudinal passage therethrough, upper and lower means on said body supporting said mandrel for longitudinal movement in said body into and from engagement with said seat, said body having orifice means ltherein between said seat and said upper means through which iiuid eX- ternally of said body can ow when said mandrel is disengaged from said seat, said lower means sealingly engaging said mandrel, means engaging said mandrel for shifting said mandrel from said seat, said body having a passage between said upper and lower means through which fluid externally of said lbody can pass for action on said mandrel to urge said mandrel into engagement with said seat -to close said orice means; said gravity valve and gas lift valve being constructed and arranged for movement as a unit through the tubular string between the top of the well bore and a desired location therein; and means connected to said gas lift valve for releasably securing said gas lift valve and gravity valve to the tubular string at such desired location.

21. In a ow device as defined in claim 17; said Valve means of said gravity valve comprising an elongate tube having a fluid passage therethrough, a valve member engageable with said tube to close said passage, said tube being deflectable laterally of said valve member to open and close said passage, shifting means for shifting said tube laterally of said valve member comprising an elongate tubular elastomer diaphragm having a substantially constant hydrostatic head of fluid acting therein and tending to shift said tube laterally of said valve member, said diaphragm also being subject to the hydrostatic head of uid in the well bore acting externally on said diaphragm to provide an external force on said diaphragm opposing the internal force therein provided by said substantially constant hydrostatic head of fluid; said gas lift valve having an elongate valve body, a valve seat in the upper portion of said valve body, a mandrel in said body and having a constantly open longitudinal passage therethrough, upper and lower means on said body supporting said mandrel for longitudinal movement in said body and for movement into and from engagement with said valve seat, said body having orifice means therein 'between said valve seat and said upper means through which duid externally of said body can ow when said mandrel is disengaged from said seat, said lower means sealingly engaging said mandrel, means engaging said mandrel for shifting said mandrel from said seat, said body having a passage between said upper and lower means through which uid externally of said body can pass for action on said mandrel to urge said mandrel into engagement with said seat to close said orice means.

22. In a tiow device as defined in claim 17; said valve means of said gravity valve comprising an elongate tube having a fluid passage therethrough, a valve member engageable with said tube to close said passage, said tube being deectable laterally of said valve member to open and close said passage, shifting means for shifting said tube laterally of said valve member comprising an elongate tubular elastomer diaphragm having a substantially constant hydrostatic head of uid acting therein and tending to shift said tube laterally of said valve member, said diaphragm also being subject to the hydrostatic head of tiuid in the well bore acting externally on said diaphragm to provide an external force on said diaphragm opposing the internal force therein provided by said substantially constant hydrostatic head of uid; said gas lift valve having an elongate valve body, a valve seat in the upper portion of said valve body, a mandrel in said body and having a constantly open longitudinal passage therethrough, upper and lower means on said body supportingr said mandrel for longitudinal movement in said body and for movement into and from engagement with said Valve seat, said body having orifice means therein between said valve seat and said upper means through which fluid externally of said body can ow when said mandrel is disengaged from said seat, said lower means sealingly engaging said mandrel, means engaging said mandrel for shifting said mandrel from said seat, said 'body having a passage between said upper and lower means through which tluid externally of said body can pass for action on said mandrel to urge said mandrel into engagement with said seat to close said orifice means; said gravity valve and gas lift valve being constructed and arranged for movement as a unit through the tubular string between the top of the well bore and a desired location therein; and means connected to said gas lift valve for releasably securing said gas lift valve and gravity valve to the tubular string at such desired location.

References Cited UNITED STATES PATENTS 2,368,999 2/1945 OLcary 103-232 2,982,226 5/1961 Peters et al 103-233 3,011,511 12/1961 Canalizo 137-155 3,089,515 5/1963 Bochan 137-610 3,223,109 12/1965 Cummings 103-232 X 3,270,765 9/1966 Waters 137-155 3,324,803 6/1967 Kelley et al 103-40 X DONLEY I. STOCKING, Primary Examiner.

W. I. KRAUSS, Assistant Examiner.

U.S. C1. XR.