US2423111A

US2423111A - Pneumatic pumping mechanism

Info

Publication number: US2423111A
Application number: US544209A
Authority: US
Inventors: Charles M O'leary
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-07-10
Filing date: 1944-07-10
Publication date: 1947-07-01
Anticipated expiration: 1964-07-01

Description

Patented July 1, 1947 UNITED STATES PATENT OFFICE PNEUMATIC PUMPING MECHANISM Charles'M. OLeary, Detroit, Mich.

Application July 10, 1944, Serial No. 544,209

20 Claims. (Cl. 103-5) The present invention relates to an apparatus for causing outow of well fluid from wells of low productivity index, and constitutes an improvement over the apparatus set forth in my co-pending application Serial No. 429,939, filed February 7, 1942. The present application, however, covers certain features common to the two.

The primary object is to provide in the bottom of the well an improved gas-operated re`- ciprocating pump. Another object is to produce, by operation of the pump, continuous aeration of the well fluid by exhausted power gas and hence a constant outflow of aerated well fluid.

Another object of the invention is to provide an improved intermitter valve which opens to produce a blow-off in the event that the Well fluid becomes too dense for aerated ow.

Other objects which will become apparent from the following specification and accompanying drawing, include the provision of an apparatus of the type mentioned which may be readily lowered into the outflow tubing of a well on the gas tubing and which is simple and rugged in design and construction.

The invention is fully disclosed by way of example in the following description and in the accompanying drawings in which:

Figure 1 is a vertical section of the device, at the beginning of the suction stroke;

Figure 2 is a similar section showing the position of parts at the beginning of the pressure stroke, and

Figure 3 is a section on the line 3--3 of Figure 2.

In Figure 1 is shown the well outflow tubing 3 which extends substantially to the bottom of the well bore within the usual well casing, noi'l shown. In the bottom of the tubing 3 is fitted an end piece 4' formed with a seat 4'. Within the tubing 3, in turn, is mounted the power gas tubing or pressure ow tube 5 to the lower end of which is fixed an enlarged tube 5 carrying a pumping mechanism designated generally by the numeral 'I'.

In the tube 5 is mounted a block I having mounted in its upper end a strainer or scale trap 8 communicating with a central passage SI formed in the block. To the block 'I is secured a downwardly extending sleeve I0 formed with a serles of ports I2 for a purpose that will presently be described. Beneath the ports a crossover I4 is attached to the sleeve IIJ and is formed with an axial passage I6 for a purpose that will presently appear. Over the passage and within the sleeve I0 is mounted an unloader valve I8 hav- ',municating with the passage 9.

ing a head 20 adapted to seat on a seat 2l at the atmospheric pressure. When the unloader valve is seated, the body thereof forms a space 29 above the crossover I4 and in communication with the ports I 2.

A jacket or extension tube 30 is suspended from the crossover I4 and is also spaced from the tubing 3 to form a continuation of the annular chamber E between tube 3 and the aligned tubes 5, I0, and 30. The lower end of the crossover is formed as a motor piston cylinder head 32 from which is suspended a motor piston cylinder 34 spaced annularly at 36 from the Jacket 30. Between the crossover I4 and the head 32 is formed a number of radial ports 38 communieating with the axial passage I6. i

In the cylinder 3-4 is slidably mounted a motor piston including a cylindrical sleeve 40 formed at its upper end with a skirt 42 of somewhat larger internal diameter. The juncture of the .two diameters forms a valve seat 44. At the lower end of the motor piston is formed a head 4B, and near the head are ports 48 forming a passage to the interior of the piston. The head 4t is formed with an axial bore 50 which has its upper end enlarged at 52 for a purpose that will presently be described. A pump plunger rod 54 passes through the bore 50 with slight clearance therein and carries at its upper end a motor piston valve head 56 adapted to close on the seat 44.

A spring 58 is inserted between the valve head and the lower piston head 4'6 and holds the valve head 56 open under certain conditions that will presently be described. The rod 54 is formed with a collar 6I) having a sliding fit in the enlarged bore 52.

On the lower end of the extension 30 is secured -a downwardly extending barrel 62 of smaller diameter and joined to the extension by an annular disk connector 64. The lower end of barrel 62 carries a fitting 63 inserted in the seat 4'.

The lower end of the pump plunger rod 54 carries a pump plunger 66 working in barrel 62. The area of the plunger 6B is smaller than the .area of the seat 44. Pump rod 54 is provided with stop collar 61 which limits the separation of the valve 56 and piston -48 in the open position of the valve.

The power gas iiows through the space 68 betweenthe connector 64 and the lower end of the motor piston cylinder 34. While disc connector acts as a lower stop for piston 40, contact, between the piston and disc u does not block communication between space 69 and the pump barrel 62.

In the lower surface of the cylinder' head 82 is mounted an upwardly opening check valve including a ball adapted to close on a seat 18'. The valve communicates through a restricted lateral passage 12 in the crossover I4 with the space 6. The passageway 12 does not communicate with the ports 68.

In the lower end of the pump barrel 62 is mounted a discharge valve housing 16 provided in its lower end with a seat 18. The housing 16.

contains a ball valve 80 adapted to close vdownwardly in the seat 18 and is formed with a suitable number of laterally extending ports 82 registering with ports 83 in the barrel through con,- necting nipples 84, thereby bringing the valve housing into communication with the lower end 6" of the well fluid space. The pump chamber between the housing 16 and pump plunger 66 is in communication with the space within Abarrel 6'2A and below housing 16 through the passages between the nipples 84, as best shown in Fig. 3.

A fluid intake pipe 88 from the well is inserted in the fitting 63 to communicate with the lower end of barrel 62. A ball valve 92 mounted be tween the housing 116 and the fitting 63 is adapted 'to seat in the upper end of the fitting 63 and',

. chamber 84 communicates through the restricted passage 12 with the space 6 which is at a pressure determined by the head of well fluid standing therein and less than the power gas pressure. However, due to the restricted passageway "12,

sure effective area of its lower side by the crosssection'al area of the plunger 66 which is attached to valve 56 by rod 60.

The downward pressure in chamber 94 is now diminishing through the restricted exhaust passage 12 while the upward gas pressure at the space 69 remains constant against the lower end of motor piston 40. The pressure effective area of the lower side of motor piston 40 which is subject to power gas pressure is its area minus the area of pump plunger 66. When the pressure in chamber 94 above the motor piston 40 drops to a point where the pressure gas on the lower side of piston 40 exerts a force greater than the force on its upper side, the piston 40, valve 56, rod 68 and plunger 66 move upward. The suction stroke of the plunger 66 is thus initiated, raising the valve 92 and seating the valve 80 by suction in the chamber 66, as shown in Figure l, drawing well fluid into the chamber 86.

As the motor piston moves upward its'speed is controlled by the size of the passage 12,.the power gas pressure and the well fluid pressure against vwhich it is exhausted. The size of the opening 12 and the relative diameters of piston 46, valve 56 and plunger 66 are so chosen for any given power gas pressure and well fluid pressure that valve 56 remains closed during the suction stroke until the skirt 42 of piston 40 strikes the cylinder head 32.y

When the extended skirt 42 strikes the head 32 at the end of its suctionV stroke, the pressure in chamber 64 further reduces, until the tension of spring 58 and the pressure responsive area on the underside of seated valve 56 are suiiicient to open the valve against its upper pressure area as shown in Figure 2. There is now equal unit pressure on both sides of the motor piston 40 and the pressure gas now exerts a resultant downward force against the area of plunger 66 toinitiate the downstroke as previously described. The opening of valve 66 in relation to seat 44 is limited by stop collar 61.

the pressure in chamber 84 may be substantially r equal t0 the pressure of the power gas supply.

This same pressure acts on both sides of valve 66, both sides 'of piston 40, and also on the top of plunger 66. During this condition, therefore,

the pressures on the piston 40 itself are balanced, and the power gas moves the plunger 66 downwardly through its pumping stroke by reason of the fact'that it is acting on an excess upwardly'- facing area on the plunger and valve unit |66 and 66 equal to the cross-sectional area of plunger 66. During the pumping stroke, that portion -of lthe powergas which -flows through passage 12 Once the valve 56 is seated it cannot come off its seat because the effective pressure area on the upper side of the valve is greater than on the lower side by'an amount at least sufficient to overcome the spring 58 and hold the valve seated. Y On the downstroke of pump plunger 66 the valve 82 is seated and valve 80 is unseated by pressure in the chamber 66, as sh'own in Figure 2. The well fluid that was previously drawn into barrel 62 is now discharged into the space 6', 6.

The motor piston 40 having come to rest on connector 64, permits the plunger 66, its pony rod and valve head 56 to continue their downward movement against the tension of spring 58. This latter movement is cushioned by the enlargement on rod 68 which exerts pressure on fluid entrapped in bore 5,2. The escape of entrapped fiuid is restricted at 50 permitting cushioning of the valve seating operation.

Exhaust of power gas through passage 12 on the suction stroke has already been mentioned.

pumping stroke, piston 40 engages disc 64 -and is brought to a stop. Thereupon continued'downvalve 56 is now held on its seat by the pressure above the motor piston 40 and the power gas pressure acting on plunger 66. When the valve 66 is seated, the pressure effective area of the upper side of the valve is greater than the pres- It is obvious that there is exhaust of power gas on the power stroke, so that the flow of gas into the head of well fluid is continuous. 'I'his flow of gas is ordinarily sufcient to produce a constantly flowing discharge of aerated well fluid to the sur face of the ground.

Back iiow of well uid into the chamber 94 is prevented by the inwardly closing check valve 10 on its seat 10'.

In the event that the head of well iiuid becomes too dense for continuous aerated discharge, the

- at the surface.

unloader valve I8 provides means for a blow-oil. This is brought about by Well iiuid pressure being ibuilt up in the outflow tubing and reacting against the area of the unloader valve |8 exposed to well Huid at the space 29. I'he unloader valve I8 is normally held seated by pressure gas acting on that portion of valve I8 confined by bellows 24, this area being substantially larger than the seated area of valve I8 on its seat 2|. The passage 22 through valve I8 is smaller in cross sectional area than the area of valve seat 2|. This provides a continuous pressure on the valve I8 tending to hold it upon its seat 2|.

When the unloader valve I8 is raised and the gas pressure is communicated to the head ol.' well iiuid at the ports I2, the friction of the flowing the valve was first unseated. This additional force insures that the valve I8 will remain open until such time as the well fluid starts to discharge The back pressure of the discharging fluid eventually drops to a point where the pressure in bellows 24 is suilicient to seat the valve. The fluid remaining in tubing 3 continues to discharge by the expansion of the power gas trapped in the tubing by the l'seating of valve I8. The quick action of the valve thus saves pressure gas and permits the pumping mechanism to commence operation without waiting for a complete blow down of the well. A balanced pressure condition, holding the pump inoperative, would be of only momentary duration.

Thus, it is not necessary with this unloader It is preferable that the well fluid pressure responsive parts of valve I8 be of a larger area than the power gas pressure responsive parts tending to hold the valve upon its seat 2|, whereby to permit the opening of valve I8 by low well uid heads.

It will be' noted that the cross sectional area of passage 22 is smaller than the area of bellows 24. When the valve I8 isaway from its seat 2|, the pressure in the area conned by bellows 24 and owing through the restricted passagek22 urges the valve on its seat. It is this force that moves the valve toward its seat when a portion of the well iiuid has been ejected at the surface and permits operation of the pumping mechanism, as previously set forth.

The higher the pressure in the system the greater the slug or head of Well uid must be to overcome the greater force exerted on the gas pressure responsive parts. If the pressure be lowered, a correspondingly smaller head will be required to open the unloader valve. A definite differential can be established between all the parts of the pumping mechanism and the unloader valve to be applicable over a Wide rangeA of varying well conditions by control of the power gas pressure.

The parts of the unloading valve are so proportioned that when the column of fluid loads up to a predetermined pressure where the performance of the pumping mechanism is retarded, the

valve opens and the power gas ejects the uidf from the tubing. Such loading up of the tubing of well fluid necessary to open the blow-on valve I8 can be controlled. The relation of the respective pressure yresponsive areas to each other can be so designed to operate under varied well' conditions and by regulation of the gas pressure can be .made to pump deep or shallow wells with a minimum of gas.

It is understood that various areas of motor pistons, valves, pump plungers and various spring tensions and sizes of vents may be used to meet various well conditions.

The disclosed pumping mechanism can be of the insert type removable with the power gas string, as illustrated, or of the tubing type requiring removal of both strings to service the pump. The pump can be so arranged as to pro duce the Well uid through thesmaller string of pipe, in which case the outer string of pipe would be used to conduct power gas to the pumping mechanism.

Although a specific embodiment of the invention has been'illustrated and described, it will be understood that various. alterations in the details of construction may be made without departing from the scope of the invention as cated by the appended claims.

What I claim is:

indil. In a gas-operated Well-pumping mechanism,

`said pump including a cylinder having a pumping chamber at one end anda pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having one end in constant uid communication with the opposite end of the pumping cylinder, a

piston in the motor cylinder, a mechanical connection between the piston and plunger, means for supplying gas under pressure alternately, first to both ends of said motor cylinder and then only to the said one end of the motor cylinder, said motor cylinder having at itsopposite end a, restricted outlet.

' 2. In a gas-operated well-pumping mechanism, a single-acting plunger pump adapted to draw liquid from a body of liquid standing in the well anddischarge that liquid into the Well tubing, said pump including a cylinder having a pumping chamber at one end and a pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having one end in constant fluid communication lwith the opposite end of the pumping cylinder, a piston in the motor cylinder, a mechanical connection between the piston and plunger, means for supplying gas under pressure alternately, iirst to both ends of said motor cylinder and then only to the said one end of the motor cylinder, said motor cylinder having at its opposite end a restricted outlet which communicates with the liquid discharged by the pump at a point in the vicinity of the pumping mechanism in orderto supply lift gas to the discharged liquid.

3. In a gas-operated well-pumping mechanism. ra single-acting plunger pump adapted to draw liquid from a body of liquid standing in the well,

and discharge that liquid into the well tubing, said pump including a cylinder having a pumping chamberat one end and a pumping plunger in. said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having one end inconstant fluid communication with the opposite end of the pumping cylinder, a piston in thev motor cylinder, a mechanical connection between the piston and plunger, means for supplying gas under pressure continuously to said onel end of the motor cylinder, valve means 0pcratcd automatically at the end of each stroke of the piston for placing the opposite end of the cylindervin communication with the source of gas under pressure at the end of the suction stroke and closing communication at the end of the pumping stroke, said motor cylinder having at its opposite end a restricted outlet.

4. In a gas-operated well-pumping mechanism adapted for attachment to the Well tubing, a single-acting plunger pump adapted to draw liquid from a body ol liquid standing in the well, and discharge that liquid into the Well tubing. said pump including a cylinder having a pumping chamber at one end and a pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having onel end in constant fluid communication with the opposite end of the pumping cylinder, a piston in the motor cylinder, a mechanical connection between the piston and plunger, means for supplying gas under pressure continuously to said one end of the motor cylinder, valve means operated automatically at the end of each stroke of the piston for placing the opposite end of the cylinder in communication with the source of gas under pressure at the end oi the suction stroke and closing communication at the end of the pumping stroke, said motor cylinder having at its opposite end a restricted outlet adapted to communicate with the well tubing in order to supply lift gas to the discharged liquid.

5, In a gas-operated well-pumping mechanism, a single-acting plunger pump adapted to draw liquid from a body of liquid standing in the well, and discharge that liquid into the well tubing, said pump including a cylinder having a pumping chamber at one end and a pumping plunger in said cylinder, a motor cylinder of larger diameterthan the pumping cylinder and having one end in constant uid communication with the opposite end of the pumping cylinder, a piston in the motor cylinder, a mechanical connection between the piston and plunger, means for supplying gas under pressure continuously to said one end of the motor cylinder, valve means carried by the piston and operated automatically at the end of each stroke of the piston for placing the opposite end of the cylinder in communication with the source of gas under pressure at the end of the suction stroke and closing communication at the end of the pumping stroke, said motor cylinder having at its opposite end a restricted outlet.

6. In a gas-operated well-pumping mechanism adapted for attachment to the well tubing, a single-acting plunger pump adapted to draw liquid from a body of liquid standing in the well, and discharge that liquid into the well tubing, said pump including a cylinder having a pumping chamber at one end and a pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having one end in constant uid communication with the opposite end of the pumping cylinder, a piston in the motor cylinder, a mechanical connection between the piston and plunger, means for supplying gas under pressure continuously to said one end of the motor cylinder, valve means carried by the piston and operated automatically at the end of each stroke of the p'iston for placing the opposite end of the cylinder in communication with the source of gas under pressure at the end of the suction stroke and closing communication at the end of the pumping stroke, said motor cylinder having at its opposite end a restricted outlet adapted to communicate with the well tubing in order to supply lift gas to the discharged liquid.

'7.-In a gas-operated well-pumping mechanism, a plunger pump adapted to draw liquid from a body of liquid standing in the well and discharge that liquid into the lower end of the well tubing, said pump having a cylinder and pump plunger, a motor cylinder, a piston assembly in said motor cylinder,'said assembly comprising a valve element and a valve seat element adapted when the valve is seated to constitute a movable piston in the cylinder and adapted when unseated to permit flow of fluid from one end of the motor cylinder to the other past the piston assembly, said pump plunger being connected to one of said elements for movement therewith, said elements being adapted to move into seating relation when the pump plunger moves away from the other element, a spring between said elements acting in a direction to unseat said valve, means for limiting movement of said other element toward both ends of the motor cylinder, means for supplying gas under pressure to that end of the motor cylinder closest to the pumping cylinder, said motor cylinder having a restricted outlet at its opposite end, the net elective areas of th valve element and the piston assembly an'd the strength of the spring being such that when the valve element is unseated the pressure acting on the assembly effects a stroke of the pump plunger in one direction, while the spring holds the valve element unseated until said other element engages said limiting means and the pressure acting on the assembly when the valve is seated effects a stroke of the pump plunger in the opposite direction and produces suiiicient back pressure at said opposite end of the motor cylinder to keep said valve element seated until said other element engages its limiting means in that direction.

8. In a gas-'operated well-pumping mechanism, a plunger pump adapted to draw liquid from a. body of liquid standing in the well and discharge that liquid into the lower end of the well tubing,

said pump having a cylinder and pump plunger,

a motor cylinder, a piston assembly in said motor cylinder, said assembly comprising a valve element and a valve seat element adapted when the valve is seated to constitute a movable piston in the cylinder and adapted when unseated to permit ilow of uid from one end of the motor cylinder to the other past the piston assembly,

said pump plunger being connected to one of said elements for movement therewith, said elements being adapted to move into seating relation when the pump plunger moves away from the other element, a spring between said elements acting inA a direction to unseat said valve, means for limiting movement of said other element toward both ends of the motor cylinder, means for supplying gas under pressure to that end of the motor cylinder closest to the pumping cylinder, said motor cylinder having a restricted outlet at its opposite end which communicates with the liquid discharged by the pump at a point in the vicinity of the pumping mechanism, the net effective areas of the valve element and the piston assembly and the strength of the spring being such that when the valve element is unseated the pressure acting on the assembly effects a stroke of the pump plunger 'in one direction, while the spring holds the valve element unseated until said other element engages said limiting means and the pressure acting on the assembly when the valve is seated effects a stroke of the pump plunger in the opposite direction and produces sufiicient back pressure at said opposite end of the motor cylinder to keep said valve element seated until said other element engages its limiting means in that direction.

, 9. In a gas-operated well-pumping mechanism, al single-acting plunger pump adapted to draw liquid from a body of liquid standing in the Well and discharge that liquid into the well tubing, said pump including a cylinder having a pumping chamber at one end and a pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having one endA in constant fluid communication with the opposite end of the pumping cylinder, a piston assembly in said motor cylinder,

said assembly comprising a valve element and a valve seat element adapted when the valve is for movement therewith, said elements being t adapted to move into seating relation when the pump plunger moves away from the other element, a spring between said elements acting in a direction to unseat said valve, means for limiting movement of said other element toward both ends of the motor cylinder, `means for supplying gas under pressure to said one end of the motor cylinder, said motor cylinder having a restricted outlet at its opposite end, the areas of said valve element and seat element and plunger and the strength of said spring being such that when the valve element is unseated the gas pressure, acting on the valve and plunger, effects a pumping stroke thereof, While the spring holds the valve element unseated until said other I, element engages said limiting means and the pressure 'acting on the net effective area of the piston assembly when the valve element is seated effects asuction stroke of the plunger and produces suiicient back pressure at said opposite end of the-motor cylinder to hold the valve element seated against the force of the spring until said other element engagesf said limiting means in the opposite direction.

10. In a gas-operated well-pumping mechanism,

ra single-acting plunger pump adapted to draw liquid from a body of liquid standing in the well and discharge that liquid into the well tubing, said pump including a cylinder having a pumping chamber at one/ end and a pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having `one f end in constant fluid communication with the optween said elements acting in a direction to unseat said valve, means for limiting movement of said other element toward both ends of the motor cylinder, means for supplying gas under pressure to said one end of the motor cylinder, said motor cylinder having a restricted outlet at its opposite end communicating with the liquid discharged by the pump at a point in the vicinity of the pumping mechanism in order to supply lift gas to the discharged liquid, the areas of said valve element and seat element and plunger and the strength of said spring being such that when the valve element is unseated the gas pressure, acting on the valve and plunger, effects a pumping stroke thereof, while the spring holds the valve element unseated until said other element engages said limiting means and the pressure acting on the net effective area of the piston assembly when the valve element isseated effects a suction stroke of the plunger and produces suillcient back pressure at said opposite end of the motor cylinder to hold the valve element seated against the force of the spring until said other element engages said limiting means in the opposite direction.

11. In a gas-operated well-pumping mechanism, a plunger pump adapted to draw liquid from a body of liquid standing in the Well and discharge that liquid into the lower end of the well tubing, said pump having a cylinder and pump plunger, a motor cylinder, a rodless piston in said motor cylinder and provided with an opening therethrough, a valve carried by said piston for controlling said opening and having a valve rod connected to said plunger, said valve being adapted to close said opening on separating movement of said piston and plunger, a spring between the piston and valve acting in a direction to open said valve, means for limiting movement of the piston in both directions, means for supplying gas under pressure to that end of the motor cylinder adjacent said plunger, saidmotor cylinder having a restricted outlet at its opposite end, the net elective areas of said piston and valve and the strength of said spring being such that when the valve is open the pressure acting on the valve effects a stroke of the plunger in one direction while the spring holds the valve open until the piston engages said limiting means and the pressure acting` on the pist'on and valve when the vvalve is closed effects a stroke of the plunger in the opposite direction and produces sufficient back pressure at said opposite end of the motor cylinder to hold the valve closed until the piston engages its limiting means in that direction.

`12. In a gas-operated well-pumping mechanism, a plunger pump adapted to draw liquid from a body of liquid standing in the well and discharge that liquid into the lower end cf the Well tubing, said pump having a cylinder and pump plunger, a motor cylinder, a rodless piston in said mtor cylinder. and provided with an openingtherethrough, a valve carried by said piston for controlling said opening and having a charged by the pump at a point in the vicinity of the pumping mechanism, the net effective areas' of said piston and valve and the strength of said spring being such that when the valve is open the pressure acting on the valve eiiects a stroke of the plunger in one direction while the spring holds the Valve open until the piston engages said limiting means and the pressure acting on the piston and valve when the valve is closed eiects a stroke of the plunger in the opposite direction and produces suicient back pressure at said opposite end of the motor cylinder to hold the valve closed until the piston engages its limiting means in that direction.

13. In a gas-operated well-pumping mechanism, a single-acting plunger pump adapted to draw liquid from a body of liquid standing in the Well and discharge that liquid into the Well tubing, said pump including a cylinder having a pumping chamber at one end and a pumping plunger in said cylinder, a motor cylinder of larger diameter thanthe pumping cylinder and having one end in constant iiuid communication with the opposite end of the pumping cylinder, a rodless piston in said motor cylinder and provided with an opening therethrough, a valve carried by said piston for controlling said opening and having a valve rod connected to said plunger, said valve being adapted to close said opening on separating movement of said piston and plunger, a spring between the piston and valve acting -in a direction to open said valve, means for limiting movement of the piston in both directions, means for supplying gas under pressure to said one end of the motor cylinder, said motor cylinder having a restricted'outlet at its opposite end, the areas of said valve and piston and plunger and the strength of said spring being su'ch that when the valve is open the gas pressure acting on the valve and plunger eiects a pumping stroke thereof while the spring holds the valve open until the piston engages said 'limiting means, and the pressure acting on the piston and the net effective area of the valve when the valve is closed effects a stroke of the plunger in the opposite direction and produces sufficient back pressure at said opposite side of the motor cylinder to hold the valve closed until the piston engages its limiting means in that direction. y

14. In a gas-operated well-pumping mechanism, a single-acting plunger pump adapted to draw liquid from a body of liquid standing in the well and discharge that liquid into the well tubing, said pump including a cylinder having a pumping chamber at one end a pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having one end in constant uid communication with the opposite end of the pumping cylinder, a rodless piston in said motor cylinder and provided with an opening therethrough, a valve carried by said piston for controlling said opening and having a valve rod connected to said plunger, said valve being adapted to close said opening on separating movement of said piston and plunger, a spring between the piston and valve acting in a direction to open said valve, means for limiting movement of the piston in both directions, means for supplying gas under pressure to said one end of the motor cylinder, said motor cylinder having a restricted outlet at its opposite end lwhich communicates with the liquid discharged by the pump at a point in the vicinity of the pumping mechanism, the areas of said valve and piston and plunger and the strength of said spring being such that when the valve is open the gas pressure acting on the valve and plunger effects a pumping stroke thereof while the spring holds the valve open until the piston engages said limiting means, and the pressure acting on the piston and the net eiective area of the valve when the valve is closed effects a stroke of the plunger in the opposite direction and produces sufficient back pressure at said opposite side of the motor cylinder to hold the valve closed until the piston engages its limiting means in that direction.

15. In a gas-operated well-pumping mechanism, a plunger pump adapted to draw liquid from a body of liquid standing in the well and discharge that liquid into the Well tubing, a pumpoperating motor comprising 'a cylinder and a piston therein, said piston being connected to the pump plunger, means for supplying gas under pressure to one end of said cylinder, a restricted outlet for the other end of the cylinder, a Valve for by-passing said piston, said valve being held closed during a stroke of the piston toward said other end of the cylinder by the back pressure developed at said end by the restricted outlet, a spring for opening said valve on a drop in said back pressure, and means for closing said valve when the piston completes its stroke in the opposite direction.

16. In a gas-operated well-pumping mechanism, a plunger pump adapted to draw liquid from a body of liquid standing in the well and discharge that liquid into the well tubing, a pump-operating motor comprising a cylinder and a piston therein-said piston being connected to the pump plunger, means for supplying gas under pressure to one end of said cylinder, a restricted outlet forthe other end of the cylinder which communicates with the liquid discharged by the pump at a point in the vicinity of the pumping mechanism in order to supply lift gas to the discharged liquid, a valve for by-passing said piston, said valve being held closed during a stroke of the piston toward said other end of the cylinder by the back pressure developed at said end by the restricted outlet, a spring for opening said valve on a drop in said back pressure, and means for closing said valve when the piston completes its stroke in the opposite direction.

17. In a gas-operated well-pumping mechanism, a single-acting plunger pump adapted to draw liquid from a body of liquid standing in the Well and discharge that liquid into the Well tubing, said pump including a cylinder having a pumping chamber at one end and a pumping plunger in said cylinder, a motor cylinder of larger diameter than the pumping cylinder and having one end in constant fluid communication with the opposite end of the pumping cylinder, a piston in the motor cylinder, a mechanical connection between the piston and plunger, means for supplying ygas under pressure to said one end of said cylinder, a restricted outlet for the other end of the cylinder, a valve for by-passing said piston, saidvalve being held closed during a stroke of the piston toward said other end of the cylinder by the back pressure developed at said end by the restricted outlet, a spring for opening said Valve on a drop in said back pressure, and means for closing said valve when the piston completes its stroke in the opposite direction.

larger diameter than the pumping cylinder andv having one end in constant fluid communication with the opposite end of the pumping cylinder, a piston in the motor cylinder, a. mechanical connection between the piston and plunger, means for supplying gas under pressure to said one end of said cylinder, a restricted outlet for the other end of the cylinder which communicates with the liquid discharged by the pump at a point in the vicinity of the pumping mechanism in order to supply lift gas to the discharged liquid, a valve for by-passing said piston, said valve being held closed during a stroke of the piston toward said other end of the cylinder by the back pressure developed at said end by the restricted outlet, a spring for opening said valve on a drop in said back pressure, and means for closing said valve when the piston completes its stroke in the opposite direction.

19. In a gas-operated well-pumping mechanism, a tubular casing constituting an extension of the well outflow tubing, a cylindrical housing co-axially mounted within and in spaced relation to said casing and having two spaced transverse walls intermediate its ends, the upper end of said housing being adapted to be secured to and in axial alignment with a gas supply pipe located within the well outflow tubing', a centrally located axial opening in the upper transverse Wall, an upwardly projecting scale trap secured in said opening, a gas-operated reciproeating motor including a co-axial motor cylinder xed with respect to and below the lower transverse wall in spaced relation to the cylindrical housing, said lower transverse wall having a passage for iiow of gas from the space between the transverse walls into the space betweenV the motor cylinder and the housing, a gas inlet port for said motor communicating with the space between the cylinder and housing, valve means in the space between said transverse Walls and opslightly less outside diameter than the inside diameter of the outow tubing, a transverse Wall in said housing, a reciprocating gas-operated motor having a cylinder secured to the lower side of said wall and extendingdownwardly therefrom in spaced relation to the housing, means for supplying gas to said motor including a gas iiow passage connecting .the space above the transverse wall with the space between the cylinder andthe housing and an inlet port for the lower end of the motor cylinder communicating with the space between the cylinder and housing, a plunger pump depending from and xed to said housing and having an inlet communicating with the well space exteriorly of the outflow tubing, and an outlet communicating with the space between the housing and tubing, and means effective to close the lower end of the tubing when the pumping mechanism is placed in position.

CHARLES M. OLEARY.

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

UNITED STATES PATENTS OLeary Aug. 22, 1944