US3010406A

US3010406A - Well apparatus

Info

Publication number: US3010406A
Application number: US679451A
Authority: US
Inventors: Renic P Vincent
Original assignee: Pan American Petroleum Corp
Current assignee: Pan American Petroleum Corp
Priority date: 1957-08-21
Filing date: 1957-08-21
Publication date: 1961-11-28
Anticipated expiration: 1978-11-28

Description

2 Sheets-Sheet l RENIC P. VINCENT R. P. VINCENT WELL APPARATUS f f 6 O 8 82 9 6 7 8 3 4 3 4 5 2 2 d 2 2 n m u E wmrw.

Nov. 28, 1961 Filed Aug. 2l. 1957 ill. Illlwlllll Il llill .llllllllln il!!! ull.

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Nov. 28, 1951 Filed Aug. 21. 1957 R. P. VINCENT WELL APPARATUS 2 Sheets-Sheet 2 11111/ 1l [Irl r lll/nfl A 7' TUR/VE Y United States Patent O 3,010,406 WELL APPARATUS Renic P. Vincent, Tulsa, Okla., assignor to Pan American Petroleum Corporation, Tulsa, Okla., a corporation of Delaware Filed Aug. 21, 1957, Ser. No. 679,451 11 Claims. (Cl. 10S- 232) This invention relates to an apparatus for controlling liquid level in a Well conduit. More particularly, this invention is directed to an improved standing valve for use in a well to limit the amount of liquid head that can be built up in ya tubing string. When a well has been ol production or shut in for a substantial period Of time, the static liquid head in the well and in a tubing string equipped with an ordinary standing' valve builds up to an elevation substantially above the dynamic or producing liquid level. Accordingly after a shut-in period in a gas lift Well, unless the usual kiclcoi or unloading valves are provided, a gas pressure substantially greater than ordinary operating pressure is required to displace the rst slug of liquid out of the tubing. The installation of kick-oit valves in the tubing is expensive and often troublesome. It is, therefore, often desirable t install only a working valve in the tubing and to avoid an excessive liquid buildup in the tubing during a shutdown period by employing a standing valve which limits the liquid head in a tubing string above a gas inlet. Flow or production can then be initiated with gas pressure not substantially greater than the pressure required to flow the well under dynamic or working conditions. Furthermore, since a constant volume of gas is typically injected at xed periods, it is oftendesirable and more efficient to lift a constant volume of liquid. The size of a liquid slug in the tubing is easily controlled by closing the tubing inlet when a predetermined pressure is built up at some point in the tubing below the working liquid level therein.

Various proposals have been made for an apparatus which would limit the buildup of a liquid head in a tubing string. These devices are adapted generally to close the tubing inlet under some predetermined pressure condition. They have generally been unsatisfactory because the pressure under which the tubing inlet is closed is generally directly or indirectly dependent upon the pressure outside the tubing, i.e., the well prsure. I have found that to be entirely satisfactory the device for controlling the maximum liquid' head in the tubing must be independent 0f the well pressure. l have also found it highly desirable to utilize the energy of the well fluids under the control of a pilot valve for opening the standing valve. In a co-pending application, S.N. 428,401, now U.S. Patent 2,865,305, filed by me on May 10, V1954, of which this application is a con- -tinuation-in-part, the effect of variations in well pressure on the maximum liquid head in the tubing has beenl overcome by using a balanced tubing inlet Valve, i.e., a foot or standing valve which has equal areas exposed on oppositeY sides of the tubing inlet. The present limit standing valve is an improvement upon that apparatus.

It is, therefore, an object of this invention to provide. an improved limit standing valve for use in a well tubing. It is also an object'of this invention to provide a standing valve which is controlled by a pilot valve,

the standing valveA being closed when the pilot valve closes and the pilot valve being affected on closing by only the pressure in the tubing, i.e., being unaffected by variations in Well pressure. It is a more speciiic object of this invention to utilize the energy of the well iiuids less of static liquid level inthe well.

3,010,406 Patented Nov. 28, 1961 rice FIGURE 1 is a cross-sectional view of a well showing an intermittent gas lift installation 4which includes au inlet or standing valve for limiting the amount of liquid in a production conduit; v

FIGURE 2 is a cross-sectional view of a schematic limit standing valve located in the bottom of a well tubing; and

FIGURE. 3 is a cross-sectional view of a preferred embodiment of an insert-type limit standing valve shownV in position in the lower end of a well tubing string;

This invention may be described in lbrief as a limit inlet or standing valve for a well tubing in which the valve is actuated by the energy of the Well fluids under the control of a pilot valve. When the standing valve is open, this pilot valve is in iiuid communication with' the fluid in the tubing and is, in the preferred embodiment, sensitive to tubing pressure and insensitive to well pressure. The standing valve is thus closed when the pilot valve closes and the pilot valve closes under a predetermined back pressure, due generally to the liquid head in the tubing. The standing valve then remains closed until the pilot valve is opened. With the pilot valve open the standing valve is opened by the energy of the well uids, more particularly Vby the differenceY between well pressure and tubing pressure.

Referring now more particularly to FIGURE l for a' more detailed description of this invention, a Well 10 is shown with intermittent gas lift equipment installed.l

The well has a casing-11 and a tubing 12 extending to the bottom of the well. The annular space 13 between the tubing and casing is clo-sed at the surface by a tubing head 14.

rations 21 which provide fluid communication betweenv the accumulation chamber and the inside of the tubing. The upper accumulation chamber head 22 may be pro vided with a 'gas lift Working valve or with perforations 23 by which gas from -the annular space 13Yis injected into the accumulation chamber to displace liquid there-r from through perforations 21 into the tubing and to the' surface. A limit standing valve 24 is placed in the bottom of the tubing at the tubing inlet 25 to control fluid ow into the tubing and the accumulation chamber, particularly to limit the height of the liquid, i.e., the liquid head in the tubing. When the liquid head in the tubing builds up to a predetermined elevation, the tubing inlet 25 is closed by the limit standing valve, regard- The first slug of liquid in the tubing may be lifted byl injecting gas into the bottom of the tubing to displace 'the slug of liquid to the surface and the gas pressure required is about the same as the pressure required tov lift subsequently produced slugs of liquid even though the liquid head 'A valve which is shown in a typical operating position at the under the control of a pilot valve actuated by tubing pressure for opening and closing a standing valveV in a tubing inlet. Other objects of this invention will be apparent from the following description in which:

lower end of tubing.12. Thelimit standing valve inlet 26 is in tluid communicationwith the tubing inlet 25 via fa passage 27 in` a horizontal tubular segment 28 which 'extends through the annular space 29betweenthel The tubing head has a side outlet 15 through which gas is injected to produce or flow 'thel Pgi'well pressure, p.s.i. Y Y

' Pt--ftubing pressure, p.s.i.

standing valve case or housing 30 and the tubing 12. This tubular segment also supports the limit standing Vval-ve concentrically in the tubing. The pilot valve assembly located in the upper end of housing 30 controls the operation of the iluid motor 32 located in the central part of the housing. This motor which is actuated by the well lluids in turn controls the position of the standing valve member 33.

The pilot valve per se comprises a pilot valve member 34 and a pilot valve port 35 in the motor cylinder head 36. The pilot valve member desirably seats upwardly against the lower side of the head. This pilot valve member is connected via valve rod 37 with a piston or movable head 38 of an enclosed pressure chamber such as a bellows 39. The bellows is filled with an expansible tluid, desirably a volatile liquid such as Freon or the like. The other end of the bellows is fixed to the upper head 40 of the limit standing valve housing. A spring 41 which is disposed in compression between the upper housing head 40 and an adjustable stop 42 on -valve rod 37 produces a force (Fp) which supplements the force of the volatile liquid in the bellows tending to open the pilot valve. The

liquid whichenters pilot valve chamber 43 through pilot valve inlet 44 exerts a pressure against the movable head 38 of thefbellows in opposition to the force of the spring and tends to close the pilot valve.

. The main tubing inlet or standing valve includes valve member 33 and a main valve port 4S in lower housing head 46. This valve is in iluid communication ywith the limit standing valve inlet 26. The main valve is actuated byA piston 48. There is a fluid passage around or through this motor piston. This may -be in the form of a loose `fitting piston in the cylinder 49 or in the -form of an weight and it desirably closes with the iiow of uid therethrough'. Arvalve spring 51 may be provided to supplement the weight of the valve and piston in closing the valve. This main valve is thus normally closed.

When this limit standing valve is lowered into the well either as an insert type valve or with the tubing, the standing valve is thus closed and the pilot valve is held open by the pilot valve spring 41. As it is lowered into the liquid in the well the liquid or, if gas ispresent, the well fluids, enters the limit standing valve housing through tubing inlet 25 and standing valve inlet 26. It liows through orice 50, through the open pilot valve and the either directly or indirectly as with a connecting rod Y47,

pilot valve inlet 44 into the tubing. The area of the pilot valve port being greater than the areaof orifice 50 in the motor piston 48 and the area of the motor piston being greater than the area of the main valve port 45,

" there is initially Van unbalance of vforces tending'to open the main'valve. VWhen'the well pressure is greater than Vthe tubing pressure, it is opened when the forceproduced ities-mamada (1) where:

A=area of piston V48, sq. in, Y Alr-area of standing valveport 45, sq.- in.

l Fg=-force .of'sp'ring '51, lbs.. (including weightof'piston f and valve member 3 3): svsoonV as thefmain valve starts to'ropenithe bottom area.

VAsthe liquid VVVhea'd'in theetubing-increases, theipre's'sure acting on the movable head S8 of the pilot valve'pressure chamber compresses this chamber and, when the valve is submerged under a predetermined head of liquid or the pressure on the bellows 39 is otherwise increased sutliciently to overcome the force of spring 41 the pilot valve is closed. This force is expressed mathematically by the following equation: Y

FD C'P-A2 f (2) where: CP=pressure in the tubing required to closeV the pilot Valve, p.s.i. Fp=force exerted by pilot spring 41, lbs. A2=area of movable head 38, sq. in.

When the pilot valve closes, llow through the oriiice 50 stops and the pressure is equalized on both sides of piston 48. The standing valve is'then closed bythe flow of the well fluids through the valve, by its own weight and by valve spring 51. As the valve becomes submerged to a greater depth, the pressure of the well fluids tending to close the valve is increased in comparison to the pressure within the tubing tending to open the valve and the standing valve is, therefore, closed with a greater force. Consequently, regardless of the submergence of the tubing in the well liquid or the pressure in the well outside the tubing, the standing valve remains closed. When the tubing has been lowered to the desired depth, packer 19 is set and the tubing is suspended on and supported by the wellhead 14. Alternatively, before the packer isset, gas pressure may be aplied to the well to displace liquid back into the formation so that the level is belowthe packer. After the packer is set, gas may be injected through intermitter valve 16 down through annulus 13y and perfov where:

0P=opening pressure, p.s.i. Fp=force exerted by pilot spring 41, lbs. Pw=well.pressure, p.s.i. A2=area of movable head 38, sq. in. A3=area of pilot valve portr35, sq. in.

Combining Equations 2 and 3 it can be seen that:

(Amm-AA.)

(A2-Aaa. (4)

OP: CP-

where:y l i 0P=opening pressure', p.s.i.

g CP=pressure in the tubing required to close the pilot valve, p.s.i.

Pw=well pressure, p.s.i. Fp=force exerted by pilot spring 41, lbs.V A2=area of-movable head 38, sq. in. A3=area of pilot valve port 35, sqlin. ,y

. When thettubing pressure has'Ibe'en-reduced to a point at which the pilot valve opens, theV area of the pilot valve port (A3) being greater thanthe area `of orice 50 (A4),

'and the pressure'above piston Y48 beingV equalized with K the tubingr'pressure Via thepilot valve :and inletV 44,- the standingv valve .also -opens. 'With the pilot'valve Vopen the standing `valve. is opened by thedifferential pressure across piston' 48 as discussedfabov'e. jAssoonV as'con' tact between the main valve member 33 and its seat is broken, the force tending to snap this valve open is indicated by the following equation:

F= (Pw-POA-Fs where F :force to snap standing valve open, lbs.

Pw=well pressure, p.s.i.

Pt=tubing pressure, p.s.i.

A=area of piston 48, sq. in. Fs=force of spring 51, lbs.

Fs being typically very small, the force (F) tending to snap the valve open after starting to open is very great.

With the standing valve open and with the well pressure substantially greater than the tubing pressure the well uids enter the tubing and raise the liquid level therein to a predetermined height, typically ZOO-500 feet or more depending upon the gas pressure available for producing the well. As the liquid head in the tubing rises, the tubing pressure approaches the closing pressure of the pilot valve which is described above. In the preferred embodiment where the pilot valve closes with, i.e., in the direction of, the flow of fluid therethrough, the well pressure as indicated above is not an element in the closing pressure of the pilot valve. =For this reason the closing of the standing valve is not affected by variations or changes in well pressure. It is affected only by the pressure in the tubing acting upon the movable head 38.

After the pilot valve has opened, the pressure above o piston 48 is equalized with the tubing pressure through the pilot valve and the standing valve is again opened as described above. Normally the standing valve is closed by the closing of the pilot valve as is also described above. In a typical apparatus the following dimensions and constants have been used with satisfactory results:

A=l`1/2 sq. in. A1=% sq. in. A=0.3 sq. in. A3=0.05 sq. in. 40 A4=0.02 sq. in.

CP=300 p.s.i.

Fs: l0 lbs.

Pw=400 p.s.i. 0P=280 p.s.i.

' For a detailed description of a preferred embodiment of the limit standing valve, reference will now be made more particularly to FIGURE 3 in which the parts are numbered to correspond to similar parts as shown in FIGURE 2'. A seating nipple 61 is connected to the lower end of tubing 12. A landing nipple 62 is connected to the lower end of this seating nipple and the lower end of the landing nipple is closed by cap 63. The tubing inlet 25 is located at an intermediate point in the seating nipple. ,55 The seating nipple has nished bores 64 and 65 immediately above and below the tubing inlet respectively to provide a seal with the insert-type limit standing valve 24' and isolate the tubing inlet. A lluid bypass 66 which is equal to the annular space 29 in the embodiment above 60 described is connected at the lower end below finished i bore 65 and at the lupper end above finished bore 64 to carry well uids from the standing valve outlet to the upper end of the seating nipple around the tubing inlet. The landing nipple 62 has an internal shoulder 67 which 65 is adapted to cooperate with the spring type holddown 68 on the, lower end of housing 30 of the removable limit standing valve to hold this housing in the proper position in the seating nipple. When the housing is in position the upper packer 69 is in upper tinishedbore 64, and the lower packer 7 Uris in the lower nished bore 65 of the seating nipple. y

'I'he limit standing valve case or housing 30 has a main or standing valve port 45 below the inlet 26 which isV opposite tubing inlet `25. Standingv valve member 33vis connected to piston 48 by rod 47. This valve member is urged downwardly against its seat 71 on the upper end of the standing valve port 45 by the weight of the valve and piston and by valve spring 51. A sleeve guide 72 attached to the lower side of head 36 in cooperation with pin 73 guides the standing valve member and aligns it with its seat. The upper end of this sleeve is threaded into head 36. Pilot valve member 34 is held upward against its seat 74 at the lower end of pilot valve port 35 by a compression spring 75, which is seated on the upper end of sleeve 72. The upper head 79 of housing 30 may have a fishing head 76 attached for removing and installing this insert type limit standing valve. A sleeve 77 is connected to and depends from this upper housing head to a position preferably below the lower end of the pilot valve bellows 39. When the uid pressure on the movable bellows head 38 is below the pilot valve opening pressure, pilot valve spring 41 between the lower end of this sleeve and adjustable stop 42 on rod 37 urges the rod extension 78 down against the pilot valve to open the pilot valve. The pilot valve bellows is connected at the top to head 79 and at the bottom to rod 37. This bellows is, as described above, lfilled with an eXpansible iluid which, in cooperating -with spring 41, exerts a downward force tending to maintain the pilot valve open.

In operation, knowing the static liquid level in a well and the available gas pressure for lifting the well, after estimating the producing liquid level, a desirable liquid slug length (Pt or CP) is selected. With these quantities fixed the various areas including particularly A2 and A3 can lbe selected to obtain from Equation 4 a desired pilot valve opening pressure (OP) which is less than the pilot valve closing pressure (CP). The standing valve is then inserted in the seating nipple, the accumulation chamber 18 and packer 19 are made up at the surface and the tubing is lowered into the well. The standing valve permits a predetermined amount of liquid to accumulate in the tubing and in the accumulation chamber as the tubing is lowered into the well and then the standing valve closes.

When the tubing is in position, preferably with the accumulation chamber near the bottom of the well, the packer is set and the wellhead connections made. Assuming that the static liquid level in the well is below perforations 23, no additional fluid can enter the tubing or the accumulation chamber after the standing valve i closes. 'When the pump has been out of operation for a longtime as is usually the case when the tubing is run and the liquid level in the well is above operating level, it is sometimes desirable toinject gas into the annular space and Vdisplace the well uids back into the formation before the packer is set. Alternatively the tubing may be swabbed to remove excess liquid after the tubing has been lowered into the well. In any case, after the packer is set, lifting' gas is injected by time-cycle intermitter valve 16 through line L7 into the annular space 13 and through perforations 23 displacing the liquid in the accumulation chamber down through perforations 21 and up-the tubing. In some cases, it is considered desirable and more economical to inject gas into the accumulation chamber 18 by use of an intermitter or operating Y valve located between the annular space 13 and the accumulation chamber. Valves of this type which are :generally actuated by the gas pressure in the annular space 13 are well known in the art. After the liquid in the accumulation chamber has been displaced out of the tubing, injection of gas into the annular space and into the top to the accumulation chamber is stopped and the pressure in the tubing drops. Pressure in the accumulation chamber then decreases to a pressure substantially v equal to the wellhead or gas separator pressure. At this low pressure, the standing valve opens permitting well tluids to enter the tubing and the accumulation chamber.

After sufficient time has elapsed to permit accumulation of sufficient Vliquid in the accumulation chamber to close Y 7 the standing valve, the intermitter valve 16 is again opened and the accumulated liquids are gas lifted to the surface. v

In an alternative and a preferred operation, the tubing is lowered into the well before the standing valve is seated.

As in the above described embodiment, the tubing is run with the accumulation chamber and packer attached. The packer is then set to seal the annular space between the accumulation chamber and the well wall at a point below the perforations 23 or other gas inlet means and above the tubing inlet. After the packer is set, a running tool is attached to fishing head 76 preferably with jars, heaxy weights, or the like and the insert standing valve is lowered into the tubing and stopped at a position a short distance above the tubing inlet 25; Gas pressure is then applied either through the Vtubing or through the annular space to displace at least part of the liquids out of the tubing and accumulationchamber back into the well and into the formations surrounding the Well. Desirably, sufficient gas pressure is -applied by this means to displace practically all of the liquid in the tubing back into the formation leaving the liquid level in the accumulation chamber at or below the working level. In some cases, it may be desirable if pressure is available to displace all of the liquids from both the tubing and the accumulation chamber. The standing valve is then lowered into position and locked in the landing nipple with the valve inlet 26 opposite the tubing inlet 25. The running tool is then disconnected from the fishing head and removed from the well. The standing valve admits well iiuids into the tubing and the accumulation chamber until the hydrostatic head is equal to the predetermined head at which the pilot and standing valves close. Inasmuch as the amount of liquid permitted to enter the gas lift system is thus limited, it can be lifted on the first producing cycle by injecting gas into' the annulus at ordinary working pressure. That is, no additional pressure or special unloading valves are required to raise an excessive accumulation of liquid in the system and kick the well oft so that it can be produced with normal operating gas pressure. It will be apparent that a running or fishing tool canbe run again and connected tothe fishing head and that the standing valve can be removed should any trouble be encountered in its operation. When the system is placed in operation again following any such extended shut-down period, the excess liquids in the well which may rise to the static liquid level of thel well are desirably removed as discussed above by displacing them back through the accumulation chamber into the producing formations and then the standing valve is seated. The system may then be placed in Y operation A*in thesame manner as above described for initiating operations after installation of the gas lifting apparatus.

From the foregoing `description which Ihas been given -by way of example of the construction and operation of the limit standing valve, it can be seen that this invention is not limited to the apparatus and methods of operation specifically described. Accordingly, this invention should be construed to be limitedY only by the scope of the appended claims. Y f l I Vclaim:V Y Y l. A standing -valve for a well conduit including a .valve inlet, a valve outlet, ay rst fluid passage between said inletand said outlet, Va standing valve including a motorfcomprising avariable volume chamber in said secv ond passage, the volume of said chamber varying with the pressure drop across said `chamber as fluid flows through said secondipassage, means connecting said-fluid motor to 'said valvexmember so that said uid rmotor controls the 8 position of said valve member, and pilot Valve means in fluid communication with and arranged for closure by the uid pressure at said outlet for controlling flow of fluid through said second fluid passage.

2. A standing valve for a well tubing including a valve inlet, a valve outlet, a standing valve port between said inlet and said outlet, a valve member adapted to close said port, a fluid motor comprising a variable volume chamber, means connecting said valve member to said fluid motor so that said valve member is opened when the volume of said chamber decreases, a conduit connecting said fluid lmotor to said inlet, and pilot'valve means adapted to be hydraulically connected with and actuated exclusively by the pressure at said outlet for venting fluid from said variable volume chamber and opening said valve member.

3. A standing valve for a well conduit including a valve inlet adapted to be in fluid communication with said conduit, a valve outlet, a first fluid passage between said inlet .and said outlet, a valve member adapted to close said first iiuid passage, a motorfcomprising a variable volume chamber, means connecting said Vmotor to said valve member so that said valve member is opened when the volume of said chamber decreases, a second iiuid passage between said inlet land said motor, and a pilot valve adapted to be hydraulically connected with and actuated by the pressure at said outlet for venting fluid from said variable volume chamber and opening said valve member.

4. An apparatus for controlling liquid level in a well tubing which has a tubing inlet comprising a standing valve housing, a housing inlet adapted to communicate with said tubing inlet, a housing outlet adapted to communicate with said tubing, a `valve port in said housing between said housing inlet and said housing outlet, a valve member adapted to close said valve port, a fluid motor comprising a variable volume chamber, means connecting said iluid'motor to said valve member for opening and closing said valve port as the pressure changes in said variable volume chamber, conduit means between said housing inlet and said uid motor, a pilot valve, and a pilot valve inlet to place saidV pilot valve in iluid com- Vmunication with said Ihousing outlet so that said pilot valve is closed` by the pressure in Vsaid tubing for controlling the ow of fluid to said motor through said conduit means, whereby the pressure at said housing outlet actuates said fluid motorv to control theV position of said valve member and thus to control said liquid level.

5. An apparatus for controlling liquid level in a well tubing including a tubing inlet, a housing within said tubing, said housing having a housing inlet in communication with said tubing inlet, and a housing outlet in fluid communication with said tubing, a standing valve port between said housing inlet and said housing outlet, a main valve member adapted' to close said standing valve port, a motor for controlling the position of said main valve member, said motor including means forming a cylinder with a cylinder head within said housing, a pis- `ton in said cylinder, means connecting said piston to said f valve member, an orifice through said piston,ja pilot valve port through said cylinder headsaid pilot valve port having a greater area than said orifice, Ymeans including a movable head formingY a variable volume chamber in the upper end of said housing, a pilot valve inlet between said tubing and said movable head, said pilot valveinlet, saidV pilot valve port, said 'orificek and saidhousinginlet `forming a fluid passage through said housing when said pilot valve port is open, a pilot valve member for closing said pilot valve port, and valverod means actuated" by the movement of said movable head for operating said pilot valve member, whereby the pressure in saidV tubing acts' upon said variable volume chamber' tocontrolthe position of said pilot valve member and wherebyrthefposition'of'said pilot Vvalve member controls theV flow Vof fluid through said fluid passage-to Ycontrolfin turn said piston and the position ofY said main valve member;V l Y 6. An apparatus according to claim including a spring means between said cylinder head and said piston normally urging said main valve member to close said main valve port.

7. An apparatus for controlling liquid level within a Itubing suspended in a well including a seating nipple mounted on the lower end of said tubing, a tubing inlet in the wall of said seating nipple, a landing nipple at the lower end of said seating nipple, means closing the lower end of said landing nipple, means forming an external uid bypass around said tubing inlet, and an insert type standing valve, said standing valve comprising a housing, a housing inlet in iluid communication with said tubing inlet, packer means on said housing above and below said housing inlet to form a iluid seal with said seating nipple above and below said tubing inlet, anchor means to removably x the position of said housing inlet with respect to said tubing inlet, a housing Outlet below said housing inlet and in fluid communication with the lower end of said bypass, a standing valve port between said housing inlet and said housing outlet, a standing valve member normally urged downwardly to close said standing valve port, means including a cylinder head and motor piston forming a pressure chamber within said housing, means connecting said motor piston to said standing valve member, -a uid passage through said motor piston, means hydraulically connecting said housing inlet with said fluid passage, a pilot valve chamber -in said housing above said cylinder head, means including a movable head forming a variable volume chamber in the upper end of said housing, said movable head being exposed on one side to a substantially constant pressure within said variable Vvolume chamber and on the other side to the iiuid pressure within said pilot valve chamber, a pilot valve inlet through said housing hydraulically connecting said pilot valve chamber with said housing outlet, a pilot valve port in said cylinder head hydraulically connecting said pressure chamber and said pilot valve chamber, said pilot valve port having substantially greater flow capacity than said tluid passage through said motor piston, a pilot valve member adapted to close said pilot valve pont, said housing inlet, said uid passage through said piston, said pressure chamber, said pilot valve port, said pilot valve chamber, and said pilot valve inlet forming a uid conduit through said housing when said pilot valve member is unseated and said pilot valve port is open, pilot valve member actuating means connected to said movable head, and spring means urging said actuating means to unseat said pilot valve member so that said pilot valve port is normally open, whereby well iluids ilowing through said iiuid conduit raise said motor piston and said standing valve mem-ber to open said standing valve port, whereby iiuid pressure within said tubing is transmitted to said movable head to close said pilot valve port and whereby the closing of said pilot valve port causes the pressure in said pressure chamber on one side of said motor piston to equalize with the pressure in said housing inlet on the other side of said motor piston and thus cause said motor piston to move said standing valve member downwardly and close said standing valve port.

8. An insert type limit standing valve for use in a tubing having a tubing inlet in the wall of a seating nipple which is connected to the lower end of said tubing and which has an external iiuid bypass around said tubing inlet, said limit standing valve including a housing, a housing inlet in the wall of said housing, a housing outlet, means to temporarily anchor said housing in position in said seating nipple so that said housing inlet is in communication with said tubing inlet and said housing outlet is in communication with said fluid bypass, packer means to seal the annular space between said housing and said seating nipple above and below said tubing inlet and direct well uids entering said tubing inlet into said housing inlet, a standing valve between said housing inlet and said housing outlet, said standing valve closing downwardly to shut off ilow through said housing, a iluid motor including a cylinder head and motor piston within said housing, means connecting said motor piston to said standing valve to open said standing valve when said piston is raised, an orifice through said motor piston, the lower side of said piston being in communication with said housing inlet at all times, a pilot valve in said cylinder head, the tlow capacity of said pilot valve being substantially greater than the iiow capacity of said orifice, spring means urging said pilot valve to close, an enclosed pilot pressure chamber including a bellows with a movable lower head, said bellows being connected at the upper end to said housing, a rod extending downwardly from said movable lower head, spring means normally urging said movable lower head and said rod to open said pilot valve, a pilot valve inlet through said housing exposing said movable lower head Ito the pressure at said housing outlet, said orifice and said pilot valve forming a uid passage between said housing inlet and said pilot valve inlet whereby, when said pilot valve is open, well fluids iiowing upwardly through said orifice in said motor piston hold said standing valve open, and whereby, when the pressure at said housing outlet which is exerted on said movable lower head is great enough to close said pilot valve against the force of said spring, iiow through said orifice vis stopped and said motor piston closes said standing valve.

9. An insert type limit standing valve for use in a well tubing having a tubing inlet in the wall of -a seating nipple which is connected to the lower end of said tubing and which has a fluid bypass around said tubing inlet, said insert type limit standing valve including a housing, a housing inlet in the wall of said housing, means to temporarily anchor said housing in said seating nipple so that said housing inlet is in fluid communication with said tubing inlet, packer means forming a iluid seal between said housing and said seating nipple Iabove and below said tubing inlet to direct well uids entering said tubing inlet to said housing inlet, a housing outlet in uid communication with the lower end of said bypass, a main valve port between said housing inlet and said housing outlet forming a vfluid passage through said housing, a main valve member adapted to close said main valve port, a tluid motor including a cylinder head and motor piston within said housing, means connecting said main valve member to the lower side of said motor piston, a pilot valve port through said cylinder head, a uid passage through said motor piston, the lower side of said motor piston being in constant communication with said housing inlet, the ow capacity of said pilot valve port being substantially greater than the liow capacity of said iiuid passage through said motor piston, a pilot valve member adapted to set against a seat on the lower side of said cylinder head and close said pilot valve pont, spring means urging said pilot valve member against said seat, a bellows including a movable lower head within said housing, means to connect the upper head of said bellows to the upper head of said housing, a rod extending downwardly from said movable lower head toward said pilot valve member, spring means normally urging said lower head and said rod downwardly to unseat said pilot valve member, pilot valve inlet means through said housing exposing said lower head to the pressure within said tubing, whereby when said pilot valve is open, the pressure drop of well uids iiowing upwardly through said uid passage in said motor piston holds said main valve member up and maintaining said main valve port open, and whereby when the pressure within said tubing which is exerted on said movable lower head is great enough to close said pilot valve member against said seat, ow of well -fluids through said iluid passage in said motor piston s stopped, the pressure across said motor piston is equalized, and said motor piston and said main valve member drop to close said main valve port.

A liquid level control device including, a well conductor, a housing, a iirst ow passage in said housing communicating with said conductor whereby well fluids fromthe formation flow through said passage into said conductor, a main valve in said passage movable to open and closed positions for controlling ow of the liquids into said conductor, a uid motor' including a variable volume chamber, means for connecting said variable volume chamber Ito said main valve whereby a decrease in the volume of said chamber causes said valve to open, a second uid passage to admit well uids from said formation to said uid motor, and means including a pilot valve actuated by the pressure at the lower end of said well'conductor for controlling flow through said second fluid passage thereby varying the pressure in said variable volume chamber and the position `of said main valve, said pilot valve being biased to remain open and in turn actuate said uid motor to hold said main valve open until the pressure at the lowerendof said conductor reaches a predetermined maximum and then being closed to shut ol flow through said second fluid passage and actuate said fluidmotor to close said main valve when the liquid level in said conductor reaches said predetermined maX- imum.

' 11. A liquid level control device including, a Well conductor, a housing within said conductor andl having a rst flow passageV communicating with said conductor whereby liquid from the formation flows via said iirst passage upwardly Ithrough said conductor, a main valve in said iirst passage movable to open and closed position for controlling upward flow of said liquid in said conductor, said main valve being normally in a yclosed position preventing flow through said rst passage, pressureactuated -motor means comprising a variable volume chamber for moving said valve to its open position as the pressure inside said variable volume chamber decreases, a second iluid passage to admit said liquid owing from said formation to said motor means, a normally open pilot valve in fluid communication with said oonductor for controlling flow through said second passage whereby the pressure is varied in said variable volume chamber, and means to close said pilot valve and thereby close said main valve when the liquid level in said conductor above said main valve reaches a predetermined maximum.

References Cited in the file of this patent UNITED STATES PATENTS 2,158,478 Parker May 16, y1939 2,597,198 Staggs et al. May 20, 1952 2,599,713 Kagay` et al. June vl0, 1952 2,622,611 Stark Dec. 23, 1952 2,865,305 Vincent Dec. 23, 1958