US 3124151 A
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Description (OCR text may contain errors)
March 10, 1964 M. M. LILLY GAS LIFT VALVE 2 Sheets-Sheet 1 Filed Aug. 31, 1961 Mama/7 M L///5/ INVENT 0R.
ATTORNEY March 10, 1964 M. M. LILLY 3, 5
GAS LIFT VALVE Filed Aug. 31, 1961 2 Sheets-Sheet 2 MaJon M Z/// INVENTOR.
ATTORNEY United States Patent Oiiice 3,124,151 GAS LEFT VALVE Mason M. Lilly, Houston, Tex, assignor to Harold Brown Company, a corporation of Texas Filed Aug. 31, 1 .961, Ser. N 135,227 3 Claims. (Cl. 137 155) This invention relates to gas lift valves and particularly to a form of valve adapted especially for use in wells where space for occupancy by gas lift valves is limited.
Present completion practices in oil well drilling are moving in the direction of employing quite small diameter casings within which the production tubing string is run. Accordingly, it has become necessary to provide artificial lift equipment which neither increases the exterior or running diameter of the tubing string nor substantially restricts the bore of the tubing.
Some current valve designs employ a concentric arrangement with respect to the tubing and embody an annular valve member constructed of flexible rubber-like material for controlling the gas injection passages, one side of the valve being exposed to loading gas pressure confined within the valve structure and the other side to the power gas in the casing annulus. Valves of this type are subject to numerous operating difficulties and provide no means for effectively adjusting the spread of the valve between opening and closing pressures.
The present invention has for its principal objects the provision of a gas lift valve which is sufiiciently compact for incorporation within the confines of the normal tubing string; which obviates the difliculties and disadvantages of more conventional constructions; which is of relatively simple but rugged construction; and which incorporates means for adjusting the spread of the valve.
An important object is the provision of an improved easing pressure-operated valve which is of very small and compact construction while possessing relatively large gas injection capacity.
A more specific object is to provide a valve unit which is removably seated in the wall of the valve body between the internal and external peripheries of the valve body so that the latter will be substantially flush in its external diameter with the tubing string in which it is mounted.
Another object is the provision of a valve unit employing pressure-loading of the valve through flexible metal bellows of relatively small cross-sectional dimensions.
ther and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful embodiment in accordance with this invention.
In the drawing:
FIG. 1 is a longitudinal sectional view of a valve in accordance with this invention;
FIGS. 2, 3, and 4 are cross-sectional views taken, respectively, along lines 22, 33, and 44 of FIG. 1; and
FIG. 5 is an exploded view in perspective of the valve, showing the pressure-loaded valve unit and the valve body with its recess for receiving the valve unit.
Referring to the drawing, the valve comprises a generally tubular body litl having an internally threaded socket 111 at its upper end and an externally threaded pin 12 at its lower end for coaxial connection of the body between sections TT of a conventional pipe or tubing string. Body iii has an externally reduced diameter section ltla extending from a point near its upper end throughout the remainder of its length to pin 12, thereby defining the downwardly facing annular shoulder 13. The latter is adapted to form a stop for a closure sleeve 14 which is slidably mountable over reduced diameter 3,124,151 Patented Mar. 10, 1964 section ltla of the body. The wall thickness of sleeve 14 is made substantially the same as the reduction in external diameter of body 10 so that when the sleeve is in place about the body, the external diameter of the valve will be substantially uniform throughout its length and no greater than the external diameter of the tubing string. By this construction, the valve will be substantially flush with the tubing string and will thereby have no radial enlargements which extend beyond the circumference of the tubing string which might otherwise interfere with the running of the tubing string in slim hole casing or which would interfere with the running of wash pipes or other tools over the exterior of the tubing string.
Closure sleeve 14 is made somewhat shorter than body ltl, terminating a short distance above pin 12. The exterior of body section lltla is provided adjacent the lower end of sleeve 14- with an annular groove 15 adapted to receive a conventional split locking ring 16 by means of which sleeve 14 may be secured against shoulder 13 and against downward displacement from the body. Seal rings 17 and 18, such as conventional O-rings, are seated in seal ring grooves 19 and 20, respectively, provided in the exterior of body section 10a near the opposite ends of sleeve 14 to form longitudinally spaced fluid-tight seals between body section 10:1 and sleeve 14 when the latter is in position about the body, as shown.
Body ltl has a longitudinally extending through-bore 21 and an angular section 22 of the wall of body 10 is substantially thickened as compared with the remainder of the body wall.
A recess, designated generally by the numeral 24, is formed in the exterior of thickened section 22 of the body for the reception of a valve unit, designated generally by the numeral 25, best seen in FIG. 5. The configuration and depth of recess 24 is such that when valve unit 25 is seated therein, the exterior of the several portions of the valve unit will fall within the confines of sleeve 14 so that the latter will readily slip over the valve unit when the sleeve is put in place to complete the assembly of the valve.
in the illustrative embodiment, recess 24 is composed of three principal portions, a lower generally rectangular portion 26, an upper generally rectangular portion 27 somewhat smaller in length than portion 26, and an elongate guide slot portion 28 substantially narrower than the portions 26 and 27 and connecting between the latter at substantially their mid-points. Guide slot portion 28 has a bottom section 29 which is arcuate in cross-section while recess portions 26 and 27 have generally fiat bottoms 3ti and 31, respectively. Lower recess portion 26 is defined by upper and lower end walls 32 and 33, respectively, and upper recess portion 27 is similarly defined by upper and lower end walls 34- and 35, respectively.
Portions of body section 10a on opposite sides of slot 23 near its lower end are cut away to form the inwardly sloping surfaces 36. Passages 37, defining discharge ports, open through surfaces 36 and communicate with bore 21 of the valve body. A sector-shaped filler 38 is secured, as by welding 39, in recess portion 26, being seated on lower end wall 33 and having a length such as to fill about one-half of recess portion 26. The exterior surface of filler 38 is curved to the same radius as body section 15in so as to be substantially flush with the exterior of the latter. Filler 38, when welded in place, effectively becomes an integral portion of body section ltla. A plurality of longitudinally spaced, transverse slots or kerfs 40 are provided in the outer surface of filler 38 and a passageway 41 extends longitudinally through filler 38 from its upper end into communication with the several kerfs 4E The latter together with passageway 41 comprise inlet passage means providing communication between the exterior of body it and the interior of recess portion 26. The latter when enclosed by sleeve 14 constitutes a valve chamber having the inlet passageway 4d and the discharge passages 37.
Valve unit 25 has an over-all configuration corresponding to the configuration of recess 24-, such that the valve unit may be bodily installed in, or removed from, recess 24- when sleeve 14 is removed from body ill. Valve unit 25 includes a valve seat housing 45 having a generally rectangular shape adapted to fit snugly in recess portion 26 between the upper end of filler 38 and upper end wall 32, the outer surface of valve seat housing 45 having a circular radius corresponding closely to that of body section 10a. Valve seat housing 45 is provided with a longitudinally extending passageway 46 adapted to register at its lower end with the upper end of passageway &1. Passageway 46 is counterbored from its upper end to provide a check valve chamber 47 in which is slidably mounted a ball check valve 48 secured to the lower end of a guide cage ball check valve 48 being thus positioned to cooperate with a seat t} defined by the inner end of passageway 46, the check valve being movable to open position by upward flow of fluid through this passageway and to close the passageway against reverse fluid flow. A packing ring '5]. is seated in the lower end of seat housing '45 surrounding passageway 46 and is adapted to seal with the upper end of filler 38 to prevent leakage of fluid between seat housing 4-5 and filler 33. An annular valve seat 52 having the axial bore constituting a port 53, is removably mounted in the upper end of counterbore 4-7.
A ball-shaped valve 55 is secured to the lower end of a plunger 56 for reciprocation relative to seat 52 for controlling port 53 to thereby control the flow of power gas between inlet passageway 41 and discharge passageways 37. Plunger 56 is threadedly secured to the lower end of a generally cylindrical stem 57 having a reduced diameter elongate extension 58 defining the upwardly facing annular shoulder 59 about the lower end of extension 58. The upper end of extension 58 is slidably received in bore 6%) of a tubular pressure dome hi, the upper end of which is connected to a generally rectangular head 62 adapted to fit snugly in recess portion 27 between end walls 34- and 35 and having a curved outer surface conforming to the curvature of body section Illa. A screw 63 having a head 64 passes through a constriction 65 in bore as and is screwed into the upper end of extension 58. Constriction 65 defines a shoulder which is abuttable from below by the upper end of extension 58 to limit upward travel by the latter and is abuttable from above by screw head 64 to limit downward movement of extension 58 and the other parts of the valve connected thereto. Head 6-2 is provided with a vertically extending passage 66 which communicates at one end with bore 60 of the pressure dome and at the other end with a transverse passage 67 which opens to one side edge of head 62 and has mounted therein a conventional check valve 68 through which pressure fluid may be introduced into pressure dome 60. A screw plug 59 closes the outer end of transverse passage 67.
Stem 57 is resiliently connected to the lower end of pressure dome 61 by means of a pair of tubular metal bellows 7t) and 71. Bellows 70' has its upper end connected to the lower end of pressure dome 61 and its lower end connected to a tubular guide sleeve 72 which surrounds extension 58. The upper end of bellows 71 is connected to the lower end of guide sleeve '72 and its lower end is connected to shoulder 59 on stem 57. With this arrangement pressure fluid contained within dome 61 will be confined inside the bellows and movement of valve 55 relative to seat 52 will be controlled by the pressure maintained in the pressure dome and inside the bellows. The external dimensions of stem 57, guide sleeve 72 and pressure dome 6d are made such that the assembled structure will fit snugly in the bottom of guide slot 28 and be 75 confined within the slot. Bellows 7t! and 71 will be slightly smaller in external diameter than the other parts, so as to avoid any rubbing on the walls of slot 28 during flexing of the bellows. It will be understood that instead of the two bellows arrangement of the illustrative embodiment, a single bellows or more than two bellows sections may be employed.
From the foregoing, it will be seen that valve unit 25 comprises seat housing 45, head 2 and the generally tubular connecting structure, including pressure dome 61, valve stem 57 and the flexible bellows connecting these elements. This valve unit may obviously be readily inserted and removed from recess 2 when closure sleeve 14 has been removed from the body. This permits ready access to the valve structure when necessary for changing pressures or for replacing worn parts, and making adjustments generally.
Bellows 76' and 71 are necessarily of quite small crosssection adapted to be fully enclosed within slot 255 and by reason of their small dimensions, can be made exceptionally strong so that they are capable of containing pressure fluid at relatively high pressures. Moreover, the effective cross-section of the bellows 7t and 71 may be made very close to the cross-sectional area of port 53 in seat 52, with the result that the spread between opening and closing pressures of the valve may be readily changed by very small changes in the area of port 53. Since seat 52 is removable, it will be seen that the spread of the valve can be easily changed to fit conditions under which the valve is intended to operate.
In operation, power gas from the casing annulus will enter through slots 44 passageway 41 and after opening check valve 48 will act against valve '55. The pressure of the power gas will, of course, be opposed by the dome pressure acting against the inside of the bellows. When the pressure of the power gas exceeds the load thus exerted on valve 55, the latter will be moved to the open position admitting power gas to passages 37 and thence into the bore of the tubing string. The pressure of any fluid column in the bore of the tubing string may be added to the pressure of the power gas to efiect opening of the injection valve. By appropriate selection of the relative cross-sectional areas of bellows and 71 and of port 53, the extent to which the fluid pressure in the tubing will be effective may be varied, as desired.
It will be noted that in the described valve construction the power gas pressure is exerted directly only against the area of valve 52 which is defined by the area of port 53 when the valve is in its closed position and, therefore, the power gas pressure does not operate directly on the effective cross-sectional area of the bellows as in more conventional casing pressureoperated gas lift valves. With the present arrangement, it becomes possible to greatly reduce the cross-sectional area of the bellows for a given sized inlet port, as compared with more conventional casing pressure-operated valve designs, while permitting substantial adjustment of the spread between the opening and closing pressures of the valve with minimum adjustment in the relative cross-sectional areas of the seat port and the bellows.
For conventional pressure loaded valves employing sealed bellows, the general formula for the ratio of the diflerence between the bellows area and the seat port area to the seat port area is A A v where A is the cross-sectional area of the bellows and A is the cross-sectional area of the seat port. In the case of more conventional bellows-type pressure loaded valves, where the seat port is exposed to tubing pressure, this ratio ranges from approximately 3 for the largest seats used to approximately 30 for the smallest seats used, a ratio of 10 being a generally average value for most such valves. In the case of valves constructed ti J) in accordance with this invention, Where the seat port is exposed to casing or power gas pressure, and the bellows to tubing pressure, the ratios would range from (where the seat port area equals the bellows area and the tubing pressure is balanced out) to 0.3 (where substantial tubing pressure eiiect is desired). A ratio of 0.1 would represent an average value. Moreover, as will be evident, in conventional casing pressure operated valves A A will be the area exposed to casing pres sure and will be large compared to A the area exposed to tubing pressure. In valves in accordance with this invention A -A will be the area exposed to tubing pressure and will, therefore, be made small compared to A the area exposed to casing pressure. In terms of A /A (ratio of bellows area to seat area) the values for conventional valves will range generally from 4 to 31, While in the valves according to the present invention, the ratio will range from 1 to 1.3.
As a result of the arrangement employed in the valves in accordance with this invention, it becomes possible to greatly reduce the cross-sectional area of the bellows relative to given port size, thereby greatly reducing the over-all dimensions of the valve. For example, a bellows having an outside diameter of 0.4 inch in a valve constructed in accordance with this invention, will pro vide the same operating spread as a bellows 1 inches in diameter in a conventional valve. Moreover, in the present valves, an increase in operating spread may be obtained with a slight decrease in seat diameter for a given bellows size, while the reverse is true with the conventional valves.
The dimensional advantages thus accruing to the valves of this invention, readily permit the compact construction described while maintaining any desired gas injection capacity for the valve. On the other hand,
it will be evident that the described valve arrangement may be employed to greatly reduce the over-all dimensions of valves mounted externally of the tubing string, thereby substantially reducing cost without loss in capacity or efficiency.
It will be understood that various conventional pressure-exerting or motor means, other than a fluid pressure-loaded bellows, may be employed to exert the desired closing force on the valve. Such alternative means may be a fluid-pressure or spring-loaded piston, a springloaded bellows rather than a fluid pressure-loaded bellows, and various combinations of such means wellknown to those skilled in this art. In every case, however, pressure-exerting or motor means will be confined against direct exposure to the power gas pressure when the valve is closed and will have an effective area exposed to the tubing pressure falling within the range of ratios to the inlet port area previously noted.
It will be seen from the foregoing that the valve in accordance with this invention fulfills the various objects previously noted.
It will be understood that various modifications and alterations may be made in the details of the illustrative embodiment within the scope of the appended claims, but without departing from the spirit of this invention.
What I claim and desire to secure by Letters Patent is:
1. A casing pressure-operated gas lift valve, comprising, a generally cylindrical body adapted for coaxial connection into a Well tubing string, a valve-receiving recess in the exterior wall of said body, an imperforate tubular sleeve slidably mounted about said body to completely enclose said recess and cooperating therewith to define a valve chamber, an inlet port communicating said valve chamber with the exterior of said body, discharge passage means communicating said chamber with the interior of said body, and a valve member and a pressure-sensitive fluid pressure loading means therefor removably mounted in said recess to control communication between said inlet and discharge passage means, the ratio of the pressure-efiective area of said pressuresensitive loading means when the valve member is in the port-closing position to that of said port being in the range of 1.0 to 1 to 1.3 to 1.
2. A casing pressure-operated gas lift valve, comprising, a generally cylindrical body adapted for coaxial connection into a well tubin' string, a valve-receiving recess in the exterior wall of said body, an imperforate tubular sleeve slidably mounted about said body to completely enclose said recess and cooperating therewith to define a valve chamber, inlet passage means communicating said valve chamber with the exterior of said body, the inlet end of said inlet passage means defining an annular valve seat defining an inlet port, discharge passage means communicating said chamber interiorly of said port with the interior of said body, and a fluid pressure-loaded valve member removably mounted in said recess to control communication between said inlet and discharge passage means, said valve member including a valve element reciprocable relative to said seat to control said port, and a flexible metallic bellows containing fluid under pressure operably connected to said valve element to urge said valve element to port-closing position, the ratio of the pressure-effective area of said bellows to that of said port being in the range of 1.0 to
1 to 1.3 to 1.
3. A casing pressure-operated gas lift valve according to claim 2 including check valve means disposed in said inlet passage means to prevent reverse fluid flow therethrough.
References Cited in the file of this patent UNITED STATES PATENTS 2,405,323 Nixon Aug. 6, 1946 2,815,764 Bryan Dec. 10, 1957 2,869,568 McCarvell Jan. 20, 1959 2,876,703 Carlisle Mar. 10, 1959