US2508174A

US2508174A - Control for plunger lifts

Info

Publication number: US2508174A
Application number: US626052A
Authority: US
Inventors: Donald G Knox; James G Abraham
Original assignee: Nat Supply Co
Current assignee: National Supply Co
Priority date: 1945-11-01
Filing date: 1945-11-01
Publication date: 1950-05-16
Anticipated expiration: 1967-05-16

Description

Maj l'16, 1950 i Dl G. KNOX Er Al. v2,508,174

comm. FOR PLUNGER uns l 3 Sheets-Sheet 1 Filed Nov. l, 1945 ='|||||||||||||||IIIIIIIIIIIIIIIIIIIIIIIl4 May 16, 1950 D. G. KNox Er AL 2,508,174

` comm. Fon rumena uns f Filed Nov. 1, 1945 3 Sheets-Sheet 2 3Q i BSU D. G. KNox Er AL comer. Fon PLUNGER LIF'rs May 16,1950

l 55 Sheets-Sheet 3 Fl'ed Nov. 1, 1945 Patented May 16, 1950 CONTROL Fon PLUNGEa Lnrrs Donald G. Knox, Long Beach, and James G. Abraham, Laguna Beach, Calif., assignors to The National Supply Company, Pittsburgh, Pa., a corporation of Pennsylvania l Application November 1, 1945, Serial No. 626,052

13 Claims. (CI. 103-52) This invention relates to the production of oil from wells and is particularly directed to an improvement in the plunger lift system normally used in raising oil in deep wells.

Plonger lift apparatus has been used for some time to produce oil from deep wells using only the energy of the formation gas or supplying additional gas from the surface where required. This method of lifting oil was devised to avoid the excessive maintenance expenses resulting from high pressures, close ts and severe alternating stresses encountered in deep well sucker rod pumps.

Essentially, plunger lift equipment comprises a string of tubing in which a plunger travels the entire distance from the top to the -bottom of the tubing and back to the top each stroke. The tubing is connected at the surface to a flow head,

which is adapted te receive the slug of ou lifted by the plunger and to direct it to the flow lines, and the tubing is fitted at its lower end with a foot-piece to stop the plunger and close a valve 'in the plunger at the end of the down stroke.

-The plunger generally has a comparatively free fit in the tubing and falls by gravity alone. It is raised by pressure of the gas under the plunger without the use of suckerrods or cable. The plunger does not lift a column of oil extending the full length of the tubing, but lifts the uid in short heads, usually not over 300 feet long.

Up to the present time the plunger lift system of raising oil has found successful application to deep wells having comparatively low bottom hole pressure, but with comparatively high volume of oil available. In such cases, it is customary to use a oomparativelylarge orifice or bean at the surface and relatively large production of oil is obtained. When it is desired to restrict the production from a well operated by a plunger lift, it has been necessary to Areduce the size of the bean at the surface. It has been found that reduction in size of the bean sometimes results in failure of the plunger to operate. A very small bean in the ilowv pipe has been found to cause valve in the plunger vto stay closed when the plunger is at the top of its travel and positioned in the ilow head. Failure of the valve to open when the plunger is in its top position re- .order to out down production. Fewer plunger trips means that the formation pressure is given a longer time to build up the pressure in the casing between trips of the plunger. Since there is a, limit to the amount of restriction which may be imposed by means of the bean, as pointed out above, it has been proposed lo limit the number of trips of the plunger by means of a timer de,- vice. It has been the experience of applicants that none of these timers haveproved successful because the plunger operation is'dependent upon well conditions and cannot be satisfactorily oper.- ated with an arbitrary timing device which is independent of weil pressures.

It is therefore the principal object of our invention to provide a control for plunger lift devices which can be -used for varying the' output from the well without disturbing regular cycling of the plunger.

Another object of our invention is to control the cycling of the plunger within'lthe wellA in accordance with pressure. variations within the well casing and the well tubing.l 1.,

Another object of our invention is toA provide a control for the operatlonvof the plunger which does not restrict now from the well during the interval while the plunger is causing the ilow of well fluid through the weil head.

Another object is to provides. control meam for a plunger lift which jwill automatically return the plunger to its position' in the bottom of the well in the event thatthe'plunger should bring up an abnormally small slug of fluid.

Other objects and advantages of our invention will appear hereinafter.

In the drawings:- ,f

Fig. 1 is an' elevation vdewwpar-tly in section. showing a common form of plunger lift apparatus, together with a preferred embodiment of our invention for controlling the operation of the plunger. l 4

Fig. 2 is a. detail view partly in section on an enlarged scale, showing details of construction of the plunger.

Fig. 3 is a plan view. partly in section, showing a main control valve and its associated mechanism which we employ in .connection with our invention. y Y l Fig. 4 is a diagrammatic elevation having oertain parts brokenl away, showing the Bourdon tubes and linkage mechanism forcontrolling 'the operation of the main control valve. The position lof the various linkage parts as shown'jin Fig. 4 causes the main control valve to remain closed. I Fig. 5 is a diagrammatic view similar to Fig. 4'

3 butwiththelinkagepartsinposltiontocam the main control valve to remain open.

Fig. 6 is a front elevation of the mechanism diagrammatically illustrated in Fiss. 4 and 5.

Fig. 'I is a sectional elevation taken substantially on the line 1-1 as shown inFig. 6.

'Ihe general view of the apparatus shown in Fig.1includesawellcasing Ilextendinginto therthandterminatingatitsupperendina control head structure generally designated II. Supported by the control head structure is a well tubing I2 extending downwardly within the casing Il and having a bumper element I3 at its lower end supported on the spring I4. A iltting I5 connects the lower end of the tubing I2 to a strainer device I6 in a manner common to the art. A plunger I1 is positioned within the tubing I2 and is adapted to travel the entire distance from the bumper element I3 near the bottom of thewelltothe control head II at the top of the well. Theupperendofthetubing I2isconnccted by a itting I8 to a depending tube I5 suspended within the control head II. Lateral ports 2l and 2l communicate with the tubing through the suspension nipple Il and the discharge nozzles 22, which are formed through the wall of the pipe 23. The pipe 23 is positioned within the suspension nipple I9 and at its upper end communicates with the valve 24 and the trap pipe 25. The upper end of the trap pipe is secured to the bumper housing 25, which encloses a rubber bumper 21 and a coll spring 2l. The upper end of the bumper housing 25 is closed by a. removable cap 29. Communication 'with the annular space within the casing Il is provided by the lateral outlets 3D and 3i, which are connected to the control head structure II. 'I'he lateral ports 20, 2|, 30 and 3l are each provided with a

valve

32, 33, 34 and 35 respectively, for controlling now through the lateral branches.

The valve 33 is connected by piping 36, crossover 31 and pipe 38 to a now beam 33 having a variable restriction. A discharge line from the ilow bean 38 extends through the conduit 4I and shutoff valve 42 to the main control valve 43 by way of inlet 44. The outlet 45 from the main control valve passes through the shutofl valve 46, to the discharge pipe 41. A bypass line 43, including a shutoff valve 49, is provided for bythe main control valve 43 if desired. I'he main control valve 43, together with its associated mechanism and piping, constitutes an essential part of the preferred embodiment ot our invention. This valve 43 as shown in outline inFig. 1 isillustrated on alarger scaleinFig. 3. The construction includes a valve -body 53 having suitable ports 5I and provided with a double scat 52. A double valve 53 mounted on a valve stem 54 is slidably mounted within the body 5l and extends upwardly through the stuffing box 55 and is secured to a connector piece 55 within the open portion 51 of the bonnet 53. An actuating rod 59 also is connected to the element 53, and extends upwardly through the threaded sleeve il and into engagement with the diaphragm head 5I mounted within the enlarged casing l2. A double compression spring 63 is within the bonnet 53 and acts against the threaded'sleeve ill at its lower end and against the spacer 1I at its upper end. The spacer 1I encircles the actuating rod 5I and is provided with a iiange 12 for contact with the double spring 53. The sleeve ill is threaded to the bonnet 5l for the purpose of adjusting the compression in the spring 63. Bolts I4 secure the bonnet 53 to the enlarged casing 52. A ilexible diaphragm 35 is provided within the casing 32 and overlies the diaphragm head 5I to deilne a chamber I6 within the casing 62 and above the diaphragm 55. A nipple 31 provided with a restricted oriilce Bl connects the casing 32 with the oil reservoir 3l.

The operation of this main control valve 43 is as follows:

Gas pressure admitted to the oil reservoir 3l through the inlet 1l forces oil to pass through the restricted orifice 5I within the nipple I1 and into the chamber 66 above the diaphragm 55. The pressure of the gas acting on the oil within the chamber 56 causes the diaphragm 3i and the actuating rod 53 to move downwardly against the action of the double spring 33. Downward movement of the control rod 58 moves the valve stem 54 downwardly and moves the double valve 53 to open the ports 52, and thereby permits now from the inlet 44 to the outlet 45.

When the gas pressure admitted into the inlet 'Il of the oil reservoir 59 drops below a predetermined intensity, the spring 53 acts to return the rod 59 and valve stem 54 upwardly to a closed position. An indicator device 13, actuated by the connector element 56, may -be provided ii desired for visually indicating whether the valve is open or closed.

In the operation of the device so far described, the plunger Il is placed within the trap 25 above the control head II and is retained in place by the valve 24. The valve 24 is then slowly opened, which irst allows the valve 14 within the plunger I1 to drop open as the gate of the valve 24 is withdrawn, and then the plunger I1 itself is released and falls through the tubing I2 to the bumper I3 at the bottom of the hole. When the plunger I I reaches the bumper element I3 at the bottom of the hole, the plunger valve 14 stops and the continuing motion of the plunger II closes the valve 14. The closing of the valve 14 prevents gas from' the formation or from the casing from by-passing through the oil accumulated in the lower end oi the tubing I2. When the pressure builds up suniciently within the casing I0 and the lower end of the tubing I2, the pressure below the plunger valve I1 raises the plunger I1 within the tubing, carrying a Slug of oil above it. When the oil reaches the nozzle openings 22, it enters the outlet branch 2I by way of the suspension nipple I3 and ilows outwardly through the piping 36, 31, 38 and through the bean 39. As the oil flows outwardly through the discharge pipe just described, the weight of the oil remaining above the plunger Il is reduced and, therefore, the plunger speed increases as the plunger I1 nears the control head II. Oil

- also rises in the trap 25 above the nozzle openings 22, and as the entrapped gas within the housing 25 and trap 25 is compressed, it acts as a cushion to decelerate the plunger which inally passes the nozzle openings 22 at relatively high velocity. When the plunger I1 comes to a stop within the control head II. just above the nozzle openings 22, the valve 'I4 within the plunger opens because the pressure above the plunger I1 is greater than the pressure below it. When the plunger valve 14 opens, the plunger Il falls back downwardly past the nozzle openings 22 and ialls through the rising column o! gas in the tubing I2 until it seats on the bumper element I3 at the bottom of the hole. The cycle then repeats in the manner described.

The control means which is contemplated by our invention is provided for regulating the cycling action of the plunger I1. 'I'he control cyclewhich we have accomplished by our invention acts as set forth in the following steps:

l. When the plunger I1 is resting on the botv tom, the tubing I2 is closed in by the main control valve assembly 43, thereby preventing escape of gas from the tubing I2. The

valves

32, 35 and the by-

pass valves

15 and 48 are all closed. -If gas is being injected into the casing I0, the valve 34 remains open. If the plunger lift is being operated on formation gas alone, the valve 34 remains closed. The normal discharge path through bean 38 and piping 40 is closed by the main control valve 43. Formation gas or gas injected into the casing I0 causes a gradual rise in pressure in both the casing I0 and the tubing I2; for example, the casing pressure may rise from 100 p. s. i. to 110 p. s. i. while the tubing pressure rises from 0 to 80 p. s. i.

2. The main control valve 43 is opened in response to the casing pressure reaching a predetermined intensity, such as 110 p. s. i. This releases the pressure in the tubing I2 down toward 0 p. s. i. and therefore the pressure under the plunger I1 lifts the plunger with its load of oil upwardly through the tubing I2 to the surface, thereby causing` the casing pressure to drop slowly; forexample, from 110 p. s. i. to 100 p. s. i. I

'I'he main control valve 43 remains open during this interval.

3. As the oil slug passes through the bean 38, piping 40 and through the

control valves

52, 53. the tubing pressure gradually rises. When a predetermined tubing pressure is reached, the main control valve 43 closes slowly at a rate to permit substantially the entire slug of oil to pass through the valve 43 before the double valve 53 finally closes. K

An important feature of the operations just described is that the main control valve 43 remains fully open during the passage of the larger portion of the slug of oil and remains completely closed during the period of accumulation of gas and oil within the lower end of the tubing I2 and in the casing I0, in order to prevent escape of gas during this interval.

The means provided for accomplishing the opening and closing of the main control valve 43 in response to pressure changes within the casing |8 and tubing I2, and in accordance with the operations set forth in steps 1, 2 and 3 above, are shown in detail in Figs. 4,5. 6 and '7.

A pressure line 18 is provided with a shuto valve 11 and communicates with the lateral port 3| leading to the casing I0 and this line 18 enters the side of a lter 18. The outlet from the lter 18 is at its upper end 18 and this outlet communicates with the inletI 80 for the casing Bourdon tube 8|. A second Bourdon tube 82 for tubing pressure is connected with the line 83. The line 83 may be connected with the valve body 50 at the port |38 in the up-streamvside of the double valve 53 or with the branch line |38 connected with the pipe 38 upstream from the pressure, pilot-to-diaphragm pressure and pilot supply pressure, respectively. The linkage mechanism, which is mounted onthe plate 88, which carries the Bourdon tubes 8| and 82, and which is mounted within the case 84, is provided for the purpose of controlling the admission of pressure into the oil reservoir 88 and hence controlling the opening and closing of the main control valve 43,.

The general principle on which this -mechanls operates is as follows:

A supply of pilot gas lunder substantially uniform pressure is admitted through a pilot supply pipe 88, and through a restriction |30. A T fitting 8| is provided in the pilot supply line 88 for directing piloty gas through the inlet line 18 to the oil reservoir 88, and also through the supply line 82 leading to the vent orifice 83. A flapper valve 84 pivotally supported at 85 is adapted in`one position to close the vent orifice 83 and in another position to swing away from the orice 83 to permit escape of gas therefrom. The opening in the vent orifice 83 is approximately twice the size of the opening in the rethe line 82 and out through the orifice 83. Therefore, no substantial pressure is applied through the line 10 to the oil reservoir 88 and hence the pressure of the oil within the chamber 88 above the diaphragm 85 is too low to overcome the pressure of the spring 83. -Therefore, the double valve 53 in the main control valve assembly 43 remains closed. When the vent orifice 83 is closed by the fiapper valve 84, the pressure of the pilot gas in the supply line passes through the inlet 10 to the oil reservoir 88 and through the orifice 88 to the chamber 88. This pressure acting over the large area of the diaphragm 85 overcomes the spring 83 and opens the control valve 43. From this description, it will be apparent that when the vent orifice 83 is open the main control valve 43 is closed, and vice versa.

As shown in the drawings, the mechanism for opening and closing the'vent orifice 83 includes a pair of ears 88 secured on a plate 88 carrying

pivot shafts

81 and 88 extending therebetween. The pivot shaft 81 supports the tubing overtravel lever 88 and the casing over-travel lever |00. Pivotally mounted upon and depending from the pivot shaft 88 is the casing pressure adjustment lever |0| and the tubing pressure adjustment lever |02. A pair of outwardly extending stationary plates |03 carry the pivot shafts 85 and |04, which extend between the plates |03 supporting the ilapper valve 84 and the arm |05. Pivotally connected with the lower end of the arm |05 is the lifting bar |08.

The casing Bourdon tube 8| is pivotally connected at its active end to the link |08. The other end of the link |08 is pivotally connected at |3| to the lever arm ||0, which is pivotally connected at |34 to the lower end of the casing pressure adjustment lever |0I. The lower end of the lever arm III) contacts an adjustment' screw carried by the depending end I|2 of the trigger H3. The trigger |I3 is pivotally mounted on the valve element II4, which is secured to the base plate 88. The tubing pressure Bourdon tube 82 is pivotally connected at its active end to the link I5. The other end of the link H5 is pivotally connected at |32 to arm ||8, which in turn is pivotally connected at -I33 to the lower end of the tubing pressure adjustment lever |02. The lower end of the arm H8 is Drovided with a foot piece ||1 adapted to abut the lower end of the arm |08.. A tension spring III is secured to the arm III and to the stationary plate II and normally acts to maintain the foot piece II'I in contact with the arm III. A spring III is provided for holding the casing over-travel lever III in engagement with the end of the adjustment screw I2I threaded through the plate II. Similarly, a spring I2| is secured tothe tubing over-travel lever' II and to the plate II for maintaining the lever II in contact with the end of an adjustment screw |22, which is also threaded through the plate II. The lower end of the tubing over-travel lever II carries a foot piece |22 adapted to contact the lower end of the tubing adjustment lever |02. One end oi the spring III is secured to the cross plate III fixed on the plates III and the other end of the spring III is attached to the lower end of the tubing pressure adjustment lever |II2.

It is to be understood that the purpose of the tubing over-travel lever II and the casing overtravel lever III. together with their springs I2I and III, and the adjustment screws |22 and I2I, is to provide adjustable limit stops for positioning the locations for the pivotal connections III between the arm III and the lever III2, and the connection III -between the arm III and the lever III. The adjustment screws |2II and |22 serve tol initially position the levers II and III and thereafter these adjustments are not changed during normal operation.

The operation of this linkage is as follows:

When the casing pressure admitted into the Bourdon tube II exceeds g pre-determined value, the active end of the Bourdon tube applies tension to the link III, thereby causing the arm III to pivot about its connection III with the lever III. This pivotal movement of the arm III causes the lower end of the arm III to move the adjustment screw III and hence the trigger III to liit the bar III upwardly as shown in Fig. 4. This moves the position of the various parts into the relationship illustrated in Fig. 5. As shown in Fig. 5, the trigger III has lifted the bar III out of engagement with the contact piece |24 which is secured to the flapper valve II and extends laterally to one side, and has permitted the ilapper valve II to seat upon and close the vent oriiice I2. With the iiapper valve Il in closed position as shown in Fig. 5, the pilot gas injected. from the supply line II is directed to the oilv reservoir II through the line III to open the main control valve 4I.

When the plunger I'I approaches the control head II in its upward movement, the pressure in the casing II begins to drop, as pointed out above. The relatively slow drop in casing pressure commences while the plunger I1 is raising a slug of oil in the tubing I2. but a much faster drop in pressure occurs in the tubing I2 and discharge line after delivery of the oil slug to the surface. This lowering of pressure in the tubing I2 is reflected by the action of the Bourdon tube I2. which then acts o n the link III to move the arm III and foot-piece II`I to the right, as viewed inFig. 5. The spring III then pulls the arm III to the right, thereby pulling the lifting bar III away from the ilapper valve I4. The bar III is then supported upon the trigger III. The lowering of the casing pressure causes the active end of the Bourdon tube II to move the link III and arm III toward the right as viewed in Fig. 5. The arm III pivots around its connection III withthe casing adjustment lever III, and moves back to the position shown in to rest on the lug III. The ilapper valve Il, however, remains seated to close off the vent passage II. The fiapper valve I4 is moved away from the vent oriilce II to return the linkage to the position shown in Fig. 4 when the plunger I'I raises a slug of oil on the next trip. The cycle of operation then repeats as described.

As shown in Figs. 6 and '7, a tension spring I2I is secured to the element III at one end and to the finger III attached to the flapper valve Il at the other end. The spring |25 acts resiliently to maintain the fiapper valve II in contact with4 the vent oriilce II.

It has been found from fleld experience that the above linkage normally acts satisfactorily to open and close the vent orifice 92 and hence operate the main control valve assembly 42 under normal well conditions. However, in the event that through some abnormal condition of the well, the plunger should raise an abnormally small slug of oil, the rise in tubing pressure might not be suilicient to cause the Bourdon tube I2 to initiate the action of opening the vent orifice I3 for effecting the delayed closing of the main control valve II. In the event of this abnormal functioning of the plunger lift apparatus, the main control valve 4I would remain open and hence would bleed oi! pressure in the tubing I2 and the casing II with consequent loss of gas and pressure. In order to remedy this possibility and avert wasting of gas, as well as to maintain normal cycling of the plunger Il, we provide an auxiliary vent |26, as shown in Fig. 7. This vent |25 is formed within the valve ele ment III and is connected to the supply line for the vent oriilce II. A closure member I2'I is pivotally supported on the valve element III and is actuated by a compression spring I2I, serving to close oif the auxiliary vent |26 under normal operating conditions. In the event that the main control valve 42 should fail to close as described above owing to the delivery of an exceptionally small slug ot oil by the plunger I1, followed by the escape of gas from the tubing f I2 and casing II, the casing pressure would fall below the pre-determined level, which would cause the arm III to rotate counter-clockwise with respect to its pivotal mounting as viewed in Fig. 4. Movement oi' the lower end of the arm III toward the right as viewed in Fig. 5 causes the arm III to engage the closure member |21 and causes it to turn on its pivotal mounting, thereby opening the auxiliary vent I2I. The discharge of pilot gas through the auxiliary vent |26 serves to release pressure within the chamber II above the valve diaphragm II and hence the spring II operates to close the double valve l2. After the casing pressure gradually increases during the interval while the discharge line is closed by the main control valve II, the casing Bourdon tube II moves the arm III clockwise as viewed in Fig. 4 to permit the spring I2I to move the closure member |21 to close the auxiliary orifice |26.

Having fully described our invention. it is to be understood that we do not wish to be limited to the details set forth, but our invention is of the full scope of the appended claims.

We claim:

1. In a plunger lift device including a well casing and a valved plunger adapted to travel freely under pressure substantially the full length of an eduction tube, and a ow conduit connected to receive flow from the eduction tube, the combina- Pig. 4. The' trigger III turns counter-clockwise 1I tion of a valve associated with the flow conduit Q, to control flow therefrom, pressure-responsive means associated with the well casing adapted to effect opening of the valve upon the casing pressure reaching a pre-determined magnitude, and meansacting to effect a delayed closing of the valve in response to pressure changes in the vflow conduit incident to raising of a slug by the plunger.

2. In a plunger lift device including a well casing and a valved plunger adapted to travel freely under pressuresubstantially the full length of an eduction tube, and a flow conduit connected to receive ilow from the eduction tube, the combination of a valve associated with the flow conduit to control flow therefrom, pressure-responsive means associated with the well casing and adapted to effect opening of the valve upon the casing pressure reaching a predetermined magnitude, means normally acting to effect a delayed closing of the valve in response to the normal pressure increase in the fiow conduit incident to raising of a slug by the plunger, and auxiliary means operable to close the valve in response to abnormally low pressure in the well casing.

v3. In a plunger-lift device including a well casing and a valved plunger adapted to travel .freely under pressure substantially the full length of an eduction tube, -the combination of a valve associated with the eduction tube to control flow therefrom, pressure-responsive means associated with the well casing and adapted to effect opening of the valve upon the casing pressure reaching a pre-determined magnitude, means normally acting to eifect a delayed closing of the valve after raising of a slug by the plunger, and auxiliary means operable to effect closing of the valve in response to abnormally low pressure in the well casing.

4. In a plunger lift device including a pair of well pipes forming a well casing and an eduction tube, a plunger adapted to travel freely under pressure substantially the full length of the eduction tube, and a flow conduit operatively connected to the eduction tube, the combination of a valve in the flow conduit, the valve having an open position and a closed position, a spring normally acting to maintain the valve in one of said positions, pressure-responsive means operable to move the valve to the other position in opposition to the spring, a control conduit carrying fluid under pressure and associated with the vpressure responsive means, a vent operatively associated with said control conduit and pressure-responsive means, means actuated by a pressure increase in one of the well pipes incident to action of the plunger and operable to close the vent whereby the valve ismoved to one position by the pressure responsive means, and additional means actuated by a pressure increase in the other well pipe incident to action of the plunger and operable to open the vent whereby the valve is moved to the other position by the spring.

5. In a plunger lift device including a pair of well pipes -forming a well casing and an eduction tube, a plunger adapted to travel freely an open position and a closed position, a spring 1 normally acting to maintain the valve in one of said positions, pressure responsive means operable to move the valve to the other position in opposition to the spring, a control conduit l0 carrying fluid under pressure and associated with the pressurev responsive means, a vent operatively associated with said control conduitY and the pressure responsive means, a Bourdon tube associated with one of the well pipes, linkage means whereby the Bourdon tube may act to close the vent upon an increase in pressure in the said well pipe incident to-action of the plunger, a second Bourdon tube associated with the other well pipe, and means including a portion of said linkage means whereby the second Bourdon tube may act to open the vent upon an increase in presf sure in the latter said well pipe incident to action of the plunger. l

6. In a plunger lift device including a well casing 'and an eduction tube, a plunger adapted to travel freely under pressure substantially the full length of the eduction tube, and a flow conduit operatively connected to the eduction tube. the combination of a valve in the flow conduit.

a spring normally acting to maintain the valveA in closed position, pressure responsive means op-f erable to open the valve in opposition to the spring, a control conduit carrying fluid under pressure and associated with the pressure ref sponsive means, a ventv operatively associated with the control conduit and the pressure re.. sponsive means, means actuated by a pressure increase in the well casing incident to action of the plunger and operable to close .the vent. whereby the valve is moved to open position byy the pressure-responsive means, and additional means actuated by a pressure increase in the eduction tube incident to action of the plunger and operable to open the vent whereby the valve is closed by the spring.

'1. In a plunger lift device including a well casing and an eduction tube, a plunger adapted to travel freely under pressure substantially the full length of the eduction tube, and a flow conduit operatively connected tothe eduction tube, the combination of a valve in the flow conduit, a spring normally acting to maintain the valve in closed position, pressure-responsive means adapted to open the valve in opposition to the spring, a control conduit carrying fluid under pressure and associated with the pressure-responsive means, a vent operatively associated with the control conduit and the pressure responsive means, a first Bourdon tube operatively connected to the well casing, linkage means whereby said Bourdon tube may act to close the vent upon a pressure increase in the well casing incident to action of the plunger, whereby the pressureresponsive means may open the valve, and a sec- `ond Bourdon tube operatively connected to the flow conduit upstream from the valve, means including a portion of said linkage means whereby the second Bourdon tube 'may act to open the vent upon a pressure increase in the flow conduit incident to action of the plunger, whereby the spring may close the valve. A

8. In a plunger lift device including a well casing, an eduction tube, a flow conduit leading from the eduction tube having a( valve associated therewith to control flow therefrom and a valved plunger adapted to travel freely under pressure substantially the full length of the eduction tube, the combination of: pressure-responsive means associated with the well casing adapted to effect opening of the valve upon the casing pressure reaching a predetermined magnitude, and means acting to efl'ect a delayed closing of the valve in response to pressure changes in the flow conduit incident to raising of a slug by the plunger.

9. In combination with a plunger lift device including a well casing. a valved plunger adapted to travel freely under pressure substantially the lull length of an eduction tube, a ilow conduit leading from the eduction tube, and a valve to control now from the ilow conduit, the improvement comprising: pressure-responsive means associated with the weil casing and adapted to effect opening of the valve upon the casing pressure reaching/a predetermined magnitude, and means normally acting to etlect a delayed closing of the valve in response to the normal pressure increase in the ilow conduit incident to raising of a slug by the plunger.

10. In a device ol the class described for opening and closing a valve in response to cyclic variations in pressure in two separate pressure members, the combination of pressure-responsive means associated with the ilrst pressure member and adapted to eilect opening of the valve upon the pressure in that member reaching a predetermined magnitude, and means normally acting to ei'iect a delayed closing of the valve in response to pressure increase in the second pressure member.

1l. In a device including two separate pressln'e members subject to cycles of change in pressure normally occurring with substantially the same frequency, and including a valve adapted to be opened and closed each cycle in response to such pressure changes, the combination of pressure-responsive means associated with the first pressure member and adapted to eii'ect opening of the valve upon the pressure in that member reaching a predetermined magnitude, and means normally acting to eii'ect a delayed closing of the valve in response to pressure increase in the second pressure member.

sure conduits each subject to cyclic variations 12 in pressure occurring with substantially the same frequency, and including a valve adapted to control the ilow through the second of the conduits in response to such pressure changes, the combination of pressure responsive means associated with the ilrst conduit and adapted to eilect opening of the valve upon the pressure in the ilrst conduit reaching a predetermined magnitude, and

means normally acting to eilect a delayed closing of the valve in response to pressure increase in the second pressure conduit.

13. In a device including two separate pressure members each subject to cyclic variations in pressure occurring with substantially the same frequency, the combination of an actuator conduit, a substantially constant pressure source, a controller device operatively connected to the pressure members, the actuator conduit and the constant pressure source, pressure responsive means associated with the controller device adapted to pressurize the actuator conduit upon the pressure in the ilrst pressure member reaching a predetermined magnitude, and additional means associated with the controller device adapted to vent the actuator conduit in response to pressure increase in the second pressure member.

.DONALD G. KNOX.

JAMES G. ABRAHAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,919,548 Fletcher July 25, 1933 1,932,452 Evans Oct. 31, 1933 1,993,292 Woods M'ar. 5, 1935