US2017353A

US2017353A - Gas lift for oil wells

Info

Publication number: US2017353A
Application number: US731163A
Authority: US
Inventors: Asbury S Parks
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-06-18
Filing date: 1934-06-18
Publication date: 1935-10-15
Anticipated expiration: 1952-10-15

Description

Oct. 15, 1935. A. s. PARKS GAS LIFT FOR OIL WELLS 2 Sheets-Sheet 1 Filed June 18. 1934 VVV I! (I (III A- Maw 5 R s o 5 ,Y Mk 5. R m 0 I n P A P l b A wwW/M Y A. S. PARKS GAS LIFT FOR OIL WELLS Oct. 15, 1935.

Filed June 18, 1934 2 Sheets-Sheet 2 INVENTOR. 5 P arks v A 2 ///////////J//// ATTORNEYS.

Patented Oct. 15, 1935 UNITED STATES PATENT OFFICE 14 Claims.

The present invention relates to devices for lifting fluid in an oil or water well by use of gas or air under pressure and the primary object of the invention is to provide a lift for oil wells which is automatic in its operation to lift the liquid in slugs from the well.

A further object of the invention is to provide a gas lift for oil wells equipped with a tubing and casing, wherein fluid is permitted to build up to a predetermined level in the tubing and then gas or air automatically injected into the bottom of the tubing for expelling the entrapped fluid in the tubing as a solid slug, the gas or air being automatically shut oil after the slug has been lifted to permit fluid to again enter the tubing.

A further object resides in the novel control arrangement for alternately admitting fluid and gas into the tubing whereby no gas will be used between lifts and gas is only admitted to the tubing when a slug of fluid is being lifted.

A still further object is to provide a gas lift device which is applicable to various types of oil wells without requiring any special tubing, and

wherein the volume of gas to be used to lift the slug of fluid need only be equal to the volumerof the tubing.

Other objects and advantages of the invention will be apparent from the following detailed description, taken in connection with the accompanying drawings forming a part of this specification and in which drawingst- Figure l is a vertical section thrua casing equipped well provided with the improved lift.

Figure 2 is an enlarged fragmentary'vertical section thru the tubing and control valve with the parts in position as when fluid is entering the bottom of the tubing.

Figure 3 is a view similar to Figure 2 but showing the parts in a position such as when the column of fluid in the tubing is being lifted.

Figure 4 is a still further enlarged fragmentary vertical sectional view thru the control valve means with parts in a position as in Figure 2.

4:, Figure 5 is a transverse section on [the line 5-5 of Figure 4.

In the drawings and wherein similar reference characters designate corresponding parts thruout the several views, the'well embodies the usual tubular well casing 6 which may extend from the ground surface to any required depth and is sealed off at its upper end by a suitable header cap 1-. Arranged within the casing 6 is a tubing or flow string 8 having its upper end extending with a sealed joint thru the head I, Connected to the lower end of the tubing 8 is a fluid actuated control valve device A and with which is operatively connected a control valve means B.

Connected to the upper end of the tubing 8 is a volume tank 9 having suflicient capacity to 5 hold the volume of fluid lifted in one stroke of the lift and of such strength as to withstand the full pressure in the well casing 6. Interposed in the line between the upper end'of the tubing 8 and the tank 9 is a valve In which may be closed to 10 shut off the upper end of the tubing when desired. Communicating with the tank 9 is a flow line H in which is provided an adjustable choke l2 for regulating the rate of flow from the tank into the flow line. A by-pass l3 connects the 5 upper end of the casing 6 with the upper end of the tubing 8 and is provided with a valve H which may be opened when desired for equaliizng the pressure in the casing and tubing. Opening into the upper end of the casing 6 is an inlet 20 -pipe l5 whereby gas or air under pressure may be injected into the casing from some external source when the natural gas pressure on the well is too. low or at too small a volume to flow the well naturally.

. 25 Referring now to the construction of the fluid actuated control valve device A, the same preterably comprises a tubular valve body i6 secured axially to the lower end of the tubing 8 in anypreferred manner and closed adjacent its 30 upper end by a top wall H. The lower end of the valve body I6 is left open and has connected thereto a sand trap l8 of any'required length to suit the particular operating conditions of the well.

Provided adjacent the central portion of the valve 35 body I6 is an internal upwardlytapering annular valve seat I! and upon which a vertically movable valve disc 20 is adapted to seat for shutting oil! communication above and below the valve seat. This valve seat is divides the tubular valve body 40 into upper and lower cylinder portions 2| and 22 respectively which align axially with the valve seat. Arranged in the upper cylinder 2i is a close fitting I upper piston 23 provided with sealing rings 24, while arranged in the lower cylinder 22 is a close 45 fitting lower piston 25 provided with sealing rings 26. Arranged in the lower cylinder 22 in spaced relation'below the lower piston 25 is a valve piston 21 provided with a series of ports 28 providing communication above and below the valve piston. 5

The

elements

23, 20, 25 and 21 are all connected in tandem and in fixed spaced apart relation by a shaft 29 so that these elements all move as a unit. Arranged in the upper cylinder 2i above the piston 23 is an expansion coil spring 30 having 55 one end acting upon the top wall I! and its opposite end acting upon the piston 23- whereby the assembly of pistons and valve disc are normally urged downwardly for engaging the valve disc 23 upon its seat l3. The compression spring 33 acts to regulate the quantity of fluid lifted at each stroke as will be more fully described.

Providing communication between the lower end of the tubing 8 and the upper portion of the sand trap I3 is a pipe 3| which at its lower end provides a port 32 opening into the lower cylinder 22 just below the lowermost point of movement of the valve piston 21. The upper end of the pipe 3| opens thru a port 33 into the tubing 3 just above thetop wall I! of the valve body l3. Providing communication between the pipe 3| and the lower cylinder 22 above the piston 23 is a pipe 34 in which is provided a ball check valve 35 permitting flow in a direction only from the cylinder 22 into the pipe 3|. The port 33 of the pipe 34 opens into the cylinder 22 at a point above the uppermost limit of movement of the lower piston bpening into the lower cylinder 22 is an intake port 31 with which an intake pipe 33 communicates. This intake pipe 33 is provided with a ball check valve 33 which allows fluid to flow only into the port 31. The lower end of the pipe 33 is internally threaded for threaded reception of a choke nipple 43. By substituting choke nipples having various sized holes drilled therethru, the rate of pumping may be regulated by increasing or decreasing the rate at which fluid may enter thru the choke nipple-and pass into the tubing thru the pipe 3|. As will be observed in Figure 2. when fluid is entering the tubing 3, the intake port 31 is uncovered so that .the fluid may pass thru the port 23 to the pipe 3|.

Opening into the upper cylinder 2| above the upper limit of movement of the piston 23 is a port 4|, while the opening into the lower portion of the cylinder 2| above the valve disc 23 when engaging upon its seat I3, is a port 42'.

Communicating at its lower end with the port 42 and extending vertically within the casing 3 to a point adjacent the upper end of the casing, is a gas line or pipe 43 being open at its upper end.

The control valve means B is associated with the tubing 3 and gas line 43 adjacent the upper end of the casing 3 and embodies a preferably tubular shell 44 interposed in and forming a portion of the pipe 43. The lower portion of the shell 44 is reduced to provide an internal annular shoulder 45 and below this shoulder with a second shoulder 43. This shell or casing 44 as will be observed is of greater diameter than the internal diameter of thepipe 43, and provides at its upper end an annular flange 4'|. Loosely fitting within the casing 44 is a bobber 43 adapted to be forced downwardly by gas passing downwardly thru the pipe 43 and being oi such construction as to permit free passage of gas when in the down position. The bobber 43 embodies a cone 49 arranged with its base uppermost and provided with a series of radially extending fins 33 which co-act with the shell 44 to retain the bobber in an upright position as the bobber moves vertically in the shell. Arranged in the lower end of the shell 44 is a compression spring 3| which acts between the shoulder 43 and the under side of the bobber for normally urging'the bobber upwardly against the annular flange 4'I.

' Referring particularly to Figure showing the relative size of the bobber 43 to the inside diameter of the pipe 43 and shell 44, the area of the annular space between the inner wall of -the shell 44 and the base of the cone 43 is greater than the cross sectional area of the pipe 43. As in Figures 4 and 5, it will be seen that the base of the cone 43 a has a diameter greater than the internal diameter of the pipe 43, and abuts against the under side of the annular flange 41.

Extending vertically at oneside of the pipe 43 with its upper end closed and its lower end opening into the shell 44 thru the top annular flange 41 thereof, is a small cylinder 52 having a port 33 at its upper end opening into the pipe 43. Vertically movable in the cylinder 22 is a piston 34 which is circumferentially recessed intermediately of its ends as at 55. The lower end of the piston 34 bears upon the base of the cone 43 whereby the piston and bobber may move together. Acting upon the upper end of the piston 54 is a compression spring 53 which acts to normally urge the piston downwardly upon the cone 43. The compression spring 5| is of such strength as to just lift the bobber 43 against the tension of spring 33.

Opening into the tubing 3 at a point well above the height of the fluid in the tubing before being ejected, is a port 51. Communicating at its upper end with the port 51 is a control pressure line 33 the lower end of which opens thru the port 4| into the upper end of the cylinder 2|. Opening at one end into the control line 33 is a cylinder 33 in which is arranged a gas tight piston 33. Secured to one side of the piston 33 is a stem 3| carrying a cone valve 32 adapted to engage upon a seat 33 for closing ofl communication thru'the pipe 33. The piston 33 is normally urged upwardly or in a direction for unseating thevalve 32 by a compression spring 34.

A pair of small

piston control tubes

33 and 33 serve to carry pressure for actuating the piston 33. The control tube 35 opens at one end into the upper end of 'the cylinder 39 and at its opposite end opens thru a port 31 into the central portion of the cylinder 32. The control tube 33 has one end opening into the control line 53 and at its opposite end opens thru a port 33 into the cylinder 32. The

ports

31 and 33 are so spaced longitudinally of the cylinder 32 as to be in communication with one another by means of the circumferential recess 55 when the piston 34 is in its upper position, and to have the port 33 closed by the upper end portion of the piston when the piston is in.its downward limit of movement and the port 31 having communication above the piston 34 and thru the port 33 with the gas line 43.

Arranged at a suitable location in the casing 3 above the control valve device A is a packer 13 which forms a gas tight seal within the casing about the tubing 3 and the pipes 43 and 53. This packer will only be required for use in'wells where gas is injected into the casing thru the pipe |5 from some source other than the'producing formation. This packer serves to keep back pressure oil? of the producing sands when artificial gas pressure is used for the lift.

Referring now to the manner in which the apparatus operates when an artificial gas pressure is required for liftingthe fluid in the tubing 3, in

- the starting position, the valve I3 is fully open,

full casing pressure 'is in the space.

tween the valve disc 28 and the piston 23 so that Since the lower side of the piston 23' and the upper face of the valve disc 28 are equalin area, no movement will be imparted to the tandem connected pistons and vaiveand the samewill beheld downwardly by the spring 38 and retain the valve disc seated. Fluid belowthe packer 10 may now enter thru the choke nipple 48 and raise the check valve' 38 so as to pass thru the intake 31; thru port 28, port 32 into the pipe 3| and out of port 33 into the bottom of the tubing .8. This will be possible since all other spaces connected with the tubing 8 are at atmospheric pressure thru the partially opened choke l2.,

Since, while fluid is entering the tubing 8, the.

cone valve 63 is, open as in Figures 2 and 4, atmospheric pressure is in the space above the piston 23.

As the oil or fluid level rises in the tubing 8, a pressure will be set up under the piston 25 tending to move the piston upwardly and this upward movement is prevented from taking place by the spring 38 until a given height or head of fluid has built up in the tubing. The duantity of fluid lifted at each stroke may be varied by varying the strength of the-spring 38 so that this spring resists opening of the valve disc 28. until a predetermined liquid level has been reached in the tubing 8. I

I When a head pressure of the fluid in the-tubing 8 acts with suflicient pressure upon the under side of the piston 25 so as to move the pistonupwardly against the tension of the spring 38, the

valve disc 28 will be raised off its seat as in Figure 3. Gas pressure in the casing 6 is now immedi ately transmitted downwardly thru the pipe; 33 unseating the bobber 48 and passes thru the port 32, under valve disc 20, out thru port 35 and unseats the ball check 35 where it flows in both directions thru the pipe 31 to the

ports

32 and 33. 4 I, Pressure acting thru port 32 passes thruthe port 28 and acts upon the under side of the piston 25 and holds the valve disc 28 in its raised open position. The check valve 38 prevents gas being blown out thru the port 31 and this escape of gas.

is also further prevented by the valve.pist on 21 which acts as an auxiliary shut off valve for the port 31 and prevents fluid from entering thru port 31 while a slug of fluid is being. ejected. Itmay here be we'll to state that in cases where loose sand is very bad, and the rate of production slow, the piston 21 may be entirely omitted. When the valve disc 20 is unseated, the pressure will now be equal on both sides of the piston 25, while the pisj ton 23 is unbalanced, atmospheric pressure existing above the piston 28 and gas pressure below the piston. This causes the elements of the control valve device tomove to the position shown in Figure 3 so that the gas under full'pre ssure flows into the lower end of the tubing 8 thru the port 33,

.The port 3'?! of the control line-'58 is arranged at an elevation along the casing 8 well above the point reached by the, 'fi'uid in the tubing before the valve 28 is lifted from its seat.. l

Since the valve 62 is unseated while the tubing was filling with fluid, atmospheric pressure exists in the control line 58. Atmospheric pressure in the line 58 permits an atmospheric pressure to exist in the cylinder 59 above the piston 68 by means of the

control tubes

65 and 66 having communication with one another by the circumferential recess 55 of the piston 54. Thus the space above and below thepiston 68 is at atmospheric pressure and allows for the spring 64 to raise the thru the pipe 43 and the bobberp48 is forced downwardly to the position shown in Figure 3 by the impact of the gas upon the fiat upper face or 5 base of the cone 49. With the bobber 48 thus forced down, the spring-56 moves the piston 54 downwardly so that the piston portion above the circumferential recess 55 closes the port 68 to the control tube 66 and'opens the port 61 of. the control tube 65 to the pressure in-the gas pipe 43 thru the port 53. Pressure in the gas pipe 43 is now transmitted thru the control tube 65 into the space above the piston 68 and the piston is forced down against the tension of the spring 64 and seats the valve 62 upon the seat 63 which seals oil the pressure in the tubing 8 from the control pressure line 58.---This position of parts is shown in Figure 3 and the parts remain in this position as long as there is gas flowing thru the gas pipe 43 into the lower end of the'tubing 8.

When all parts of the apparatus are in the position shown in Figure 3, gas is flowing into the top end of the gas line- 43 and thru the device A into the bottom of the tubing 8 under the head of fluid as previously described. Suflicient gas pressure is maintained in the casing 6 so that the fluid in the tubing is blown out as a slug and not aerated. The fluid slug travels upwardly in the tubing 8 thru the open valve i8 and into the volume tank 8 and since the volume tank is large enough to hold the entire volume of fluid blown out at one stroke, the entire tubing will be cleaned of the fluid. The adjustable choke i2 is set so that the pressure within the tubing 8 will build 3 nal position against the flange 41 by the spring 5!. Raising of the bobber 48 raises the piston 54 to the position in Figure 4 thus shutting off the pressure in the pipe 43 from above the piston 68 5 and opening communication between the

tubes

65 and 66. Since pressure in the control line 58 is still atmospheric, the pressure from above piston 68- exhausts thru tube 65, circumferential recess' and tube 66 into the control line 58. This 5 allows" for the'spring 64 to raise the piston 68 and unseat the cone valve 62 from its seat 63. Since the pressure in the tubing 8 at this time is equivalent to the casing pressure, opening of the cone valve 52 permits the pressure in the 55 tubing 8to be transmitted thru the port 51 and control line 58 into the chamber above the upper piston 23 thru the port 4!. This pressure above the piston 23 causes the pressures to become equalized on both sides of the

pistons

23 and 25 and allows for the spring 38 to move the

pistons

23, 25 and 21 down to their original position and seat the,.valve disc 28. The ball valve 35 seats v as soon as gas flow stops. Thus, all moving parts arev returned to their original position before the slug of fluid is fully exhausted from the volume tank 9. The pressure in the tubing 8 forces the fluid out of the volume tank 9 into the flow line H and when the last of the fluid has been ex- 70 pelled thru the choke |2, the gas in the-tubing will quickly flow out thru the choke so that the pressure inthe tubing is again reduced to atmospheric. With pressure in the tubing 8 and communicating parts reduced to atmospheric pressure, the lift is in a condition for another cycle tion, the packer is not employed and the oil ispermitted to build up in the casing toany suitable level between the nipple Ill and the upper end ofthe gas line 43. In other respects, the lift 10 functions in a like manner as. that described when the packer 10 is required and an artificial gas pressure is employed.

The by-pass I3 with the valve l4 provides a means whereby the lift may be stopped from operation temporarily and it is not desirable to bleed the casing pressure down to atmospheric. To accomplish this, the valve ill is closed and the valve It opened so as to equalize pressure in the casing and tubing. With these pressures equal, there will be no differential pressure to blow the slug of oil out of the tubing. Fluid will, however, be permitted to enter thru the-choke nipple 40 until sufiicient head has built up in the tubing 8 so as to raise the piston and open the 25 valve disc 20. Raising of the piston 25 will close the port 31 and stop further fluid from entering the tubing. To start operation again, it is merely necessary to close valve ll and open valve l0. By ejecting the column of oil from the tubing in a slug, a high oil velocity thru the tubing is obtained and this high velocity will tend to flush out any paraflin deposits collecting in the tubing.

Various changes in the shape, size and arrangement of parts may be made to the form of in- 35 vention herein shown and described, without .de-

parting from the spirit of the invention or the scope of the following'claims.

I claim: 1. In a gas lift for wells including a tubing, a

40 fluid actuated control device on the lower end of the tubing and'having a liquid inlet thru which liquid rises in the tubing, valve means in the control device operable upon a given head of liquid in the tubing to close the liquid inlet and admit air under pressure into the tubing beneath the column of liquid therein, and control valve means automatically operable by a back pressure in the tubing for providing a pressure differential upon the valve means in the control device to cause opening of the liquid inlet and shutting oif entrance of gas to the tubing after the column of liquid has been ejected from the tubing.

2-. In a gas lift'for wells including a tubing, a fluid actuated control device on the lower end of the tubing and having a liquid inlet submerged in the liquid to be lifted and thru which liquid rises in the "tubing, valve n eans'in the control device operable upon a given head ofliquid in the tubing to close the liquid inlet and admit gas 6.0 under pressure into the tubing beneath the column of liquid therein, a volume tank in communication with the upper end of the tubing and having a choke opening to a flow line, and control valve means automatically operable by the back pressure in the tubing to actuate the valve means in the control device to cause opening of the liquid inlet and shutting off entrance of gas to the tubing after the column of liquid has been ejected from the tubing.

- 3, In a gas lift for wells including a tubing.

a fluid actuated control device on the lower end of the tubing and having a liquid inlet thru which liquid is permitted to rise in the tubing, valve means in the control device operable upon a given head of liquid in the tubing to ciou the liquid inlet and admit gas under pressure into the tubing beneath the column of liquid therein. a volume tank in communication with the upper end of the tubing and having a choke opening to a flow line, and control valve means automati- 5 cally operable upon equalization of pressure in the tubing with that of the gas supply to actuate the valve means in the control device to cause opening. of the liquid inlet and shutting off es- I cape of gas to the tubing after the column of 1 liquid has been ejected from the tubing into the volume tank.

4. In a gas lift for wells including a tubing, a fluid actuated control device on the lower end of the tubing having a liquid inlet thru which 15 liquid is permitted to rise in the tubing and a gas inlet communicating with the lower endof the tubing, a check valve in the liquid inlet permitting flow of liquid to the tubing, a check valve in the gas inlet permitting flow of gas to the 20 tubing, valve means in the control device operable upon,-a given head of liquid in the casing to close the liquid inlet and admit gas under pressure into thetubing thru the gas inlet beneath the column of liquid 'in the tubing, a vol- 25 ume tank at the upper end of the tubing and having a restricted outlet opening to a flow line, and control valve means automatically operable upon equalization of pressure in the tubing with that of the gas supply to actuate the valve means 30 in the control device to cause opening of the liquid inlet and shutting oif entrance of gas to the tubing after the column of liquid has been ejected from the tubing into the volume -tank.

5. In a gas lift for wells including a casing 35 sealed at its upper end and a tubing within the casing, a fluid actuated control device on the lower end of the tubing and having a liquid inlet thru which liquid passes from the casing and rises in the tubing, valve means in the control 40 device operable upon av given head of liquid in the tubing to close the liquid inlet and admit gas under pressurefrom the upper portion of the casing into the tubing beneath the column of liquid therein, a volume tank into which the 5 upper end of the tubing opens, a flow line for the tank, a choke in said flow line, and control valve means automatically operable thru equalization of pressures in the tubing and casing to actuate the valve means in'the control device 50 and cause opening of the liquid inlet and shutting of! entrance of gas to the tubing after the column of liquid has been ejected from the tubing into the volume tank.

6. In a gas lift for wells including a casing 55 sealed at-its upper end and a tubing within the casing, a fluid actuated control device operable upon a given head of liquid in the tubing to shut off entrance of liquid to the tubing and admit gas under pressure into the tubing "beneath the 60 column of liquid therein, and control valve means automatically operable upon equalization of pmsures in the casing and the tubing to permit entrance of liquid into the tubing and shutting off entrance of gas to the tubing. 5-

- 7. In a gas liftfor wells including a casing closed at its upper end and a tubing within .the

casing, a control device at the lower end of the tubing and having a liquid inlet thru which liquid in the casing is permitted to rise in the tub- 70:

ing, valve means in the control device operable upon a given head of liquid in the tubing to close the liquid inlet and admit gas under pressure in the easing into the tubing beneath the column of liquid therein, a volume tank for the 75 upper end of the tubing, a flow line from the tank, a choke in the flow line' for providing a back pressure in the tubing, a control line between the tubing and control device, and fluid pressure operated valve means in the control line operable when the pressure in the tubing equalscasing pressure to permit actuation of the valve means in the control device for opening the liquid inlet and shutting off entrance of gas to the tubing.

8. In a gas lift for wells including a casing closed at its upper end, and a tubing within the casing, a fluid controlled device at the lower end of the tubing having a liquid inlet thru which liquid in the casing is permitted to rise in the tubing, a gas inlet communicating with the bottom of the tubing, tandem connected valve means in the control device operable upon a given head of liquid in the tubing to close the liquid inlet and open the gas inlet, a volume tank connected to the upper end of the tubing and having an adjustable outlet to a flow line, a gas line communicating with the gas inlet and extending verticallyto the upper portion of the casing, a bobber in the gas line, a control line between the tubing and control device, and a control valve in the control line and controlled by said bobber to permit actuation of the tandem connected valve means for opening the liquid inlet and closing the gas inlet after the column of liquid has been ejected from the tubing into the volume tank. i i

9. In a gas lift for wells including a casing closed at its upper end and a tubing within the casing, a fluid controlled device at the lower end of the tubing having a liquid inlet thru which liquid in the casing passes and rises in the tubing, a gas inlet thru the device to the tubing, tandem connected valve means in the fluid controlled device operable upon a given head of liquid in the tubing to close the liquid inlet and open the gas inlet, a check valve in each of said inlets permitting flow to the tubing, a volume tank for the upper end of the tubing and having an adjustable outlet opening to a flow line, a

control line between the fluid controlled device and the tubing above the liquid level attained therein, a gas line communicating at its lower end with the gas inlet and having an open upper end adjacent the upper end of the casing, a bobber in the gas line and moved downwardly by passage of gas, a. fluid pressure operated valve in the control line, and means actuated by the bobber to control movement of the fluid pressure operated valve for closing the control line while gas is being ejected into the tubing and opening the" control line upon stopping of gasflow thru the gas line-to permit actuation of the tandem connected valve means for opening the liquid inlet and closing the gas inlet.

10. In a gas lift for wells including a casing closed at its upper end and a tubing within the casing, a control device secured to the lower end of the tubing embodying a tubular valve body providing upper and lower cylinder portions, a valve seat between the cylinder portions, a piston movable in each cylinder portion, a shaft 'connecting the pistons, a valve disc on the shaft for engaging upon said seat, spring means normally urging the pistons downwardly and seating the valve disc, a liquid inlet into the valve body beneath the lower piston, a check valve in the inlet, a pipe forming communication between the bottom of the, tubing and the valve body below the lower piston, a passageway forming communipiston, a control line opening into the valve body 5 above the upper piston, a bobber in said gas line, said control line opening into the tubing adjacent the upper end, and fluid pressure operated valve means in the control line and controlled by said bobber to permit closing of said valve disc and permit entrance of liquid into the tubing, said liquid when rising to a given height in the tubing to cause opening of the valve disc.

11. In a gas lift for wells including a casing closed at its upper end, and a tubing within the 5 casing, a fluid controlled device at the lower end of the tubing having a liquid inlet thru which liquid in the casing is permitted to rise in the tubing, and a gas inlet, a check valve in the liquid inlet permitting flow into the tubing, piston 20 operated valve means in the control device operable uponla given head of liquid in the tubing to open the gas inlet and admit gas under pressure in the casing into the tubing beneath the column of liquid therein and permit closing of 25 the liquid inlet check valve, a volume tank connected with the upper end of the tubing and having an adjustable outlet opening to a flow line, and control valve means automatically operable by a back pressure in the tubing to cause actua- 30 tion of the valve means in the control device for closing communication thru the gas inlet and permitting opening of the liquid inlet valve after the column of liquid has been ejected from the tubing into the volume tank.

12. In a gas lift for wells including .a casing closed at its upper end, and a tubing within the casing, a fluid controlled device at thelower end of the tubing and having a liquid inlet thru which liquid in the lower portion of the casing is per- 40 mitted to rise in the tubing, and a gas inlet, a packer sealing the casing above the liquid inlet, means for admitting gas under pressure into the casing above the packer, agas line providing communication between the gas inlet and the casing 45 above the packer, valve means in the control device operable upon a given head of liquid in the tubing to open the gas inlet and cause closing of the liquid inlet, a volume tank for the upper end of the tubing and having an adjustable outlet 50 opening into a flow line, and fluid pressure operated means controlled by passage of gas thru the gas line to cause actuation of the valve means in the fluid control device for closing the gas inlet and permitting opening of the liquid inlet 55 after the column of liquid in the tubing has been ejected into the volume tank.

13. In agas lift for wells including a casing closed at its upper end, and a tubing within the casing, a fluid actuated control device at'the lower end of the tubing and having a check valve controlled liquid inlet thru which liquid is per-, mitted to rise in the tubing, a packer sealing the casing above the control device, means for admitting gas under pressure into the casing above '66 the packer, a gas line between the upper portion of the casing and the control device, valve means in the control device operable upon a given head of liquid in the tubing to admit gas into the tubing beneath the column of liquid therein and 70 let after the column of liquid in the tubing has been ejected into, the volume tank.

14. In a gas lift for wells including a casing -'c1os ed at its upper end, and atubing 'within the casing, a controhdeyibe at the lower end 01' the tubing having a gas inlet'and a liquid inlet, said liquid inlet permitting liquid in the casing to rise in the tubingja packer sealing thecas'ing above the liquid inlet, valve means in the control device operable upon a given head of liquid in the tubing to openjthe-ga's permit closing of the liquid inlet, "e, volume tank having an adjustable outlet opening into a flow line, a pipe connecting the upper end of the tubing with the volume tank.

a valve in said pipe, means for admitting gas under pressure into the casing above the packer,

- a valve controlled by-pass between the tubing and casing above the packer, and fluid pressure operated means operable by a back pressure in the tubing tor controlling movement of the valve means in the control device to cause closing of m the gas inlet after the column or liquid in the tubing has been ejected into the volume tank.

ASBURY S. PARKS.