US3005413A - Rod-type fluid operated pumping system - Google Patents

Description

Oct. 24, 1961 c. J. COBERLY ROD-TYPE FLUID OPERATED PUMPING SYSTEM 7 Sheets-Sheet 1 Filed April 1, 1957 (Twas/vars Q]: ass/my,

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Oct. 24, 1961 c. J. COBERLY ROD-TYPE FLUID OPERATED PUMPING SYSTEM 7 Sheets-Sheet 2 Filed April 1, 1957 u a w m 4 i I; 5 0 I J a: a J; 2 Z H E a @Jfl a f M a m m a w 1 Z 6 W w B 1% I: M W w w 5 6 0 W, wm M 0/ m 1 1.. IE1 1 f 0 6 M. [fab M WW Oct. 24, 1961 c. J. COBERLY 3,005,413

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Oct. 24, 1961 c. J. COBERLY ROD-TYPE FLUID OPERATED PUMPING SYSTEM '7 Sheets-Sheet 4 Filed April 1, 1957 Z 5% V w 0 E 2 W fir A 7/ a ME G a 5 Get. 24, 1961 c. J. COBERLY 3,005,413

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Oct. 24, 1961 c. J. COBERLY ROD-TYPE FLUID OPERATED PUMPING SYSTEM 7 Sheets-Sheet fie, 8.

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ROD-TYPE FLUID OPERATED PUMPING SYSTEM Filed April 1, 1957 7 Sheets-Sheet '7 3,065,413 KGB-TYPE FLUID GPERATED PUMPING SYSTEM Clarence I. Qoberly, San Marino, Califl, assignor to Kobe, 111C. Huntington Park, Califi, a corporation of Cali= fomia Filed Apr. 1, 1957, Ser. No. 649,888 17 Claims. (Cl. 103-46) The present invention relates in general to producing oil wells with fluid operated pumping units and, more particularly, with fluid operated pumping units of the rod type. Fluid operated rod-type pumping units have various advantages over beam operated units of this type, one being that they may readily be operated at slow speeds with long strokes to minimize the eflects of stretching of the rod and tubing strings. This is particularly important in deep wells, wherein the rod strings may stretch substantial proportions of the strokes attainable with beam operated pumping units. Another advantage of fluid operated pumping units of the rod type is that they provide straight lifts directly over the well heads, which is particularly desirable with long stroke units. These and other advantages may be achieved with pumping units which are operated either hydraulically or pneumatically, or which are capable of combined hydraulic and pneumatic operation.

The present invention further relates to an integrated system for pumping two or more wells each equipped with one of the fluid operated rod-type pumping units of the invention, or one equipped with such a pumping unit and the others equipped with conventional fluid operated bottom-hole pumping units, the various pumping units being supplied with operating fluid under pressure from a central station. Thus, a single source of pressurized operating fluid may be utilized to power any desired number of the pumping units of the invention.

A primary object of the invention is to provide such a fluid operated pumping system wherein each pumping unit draws from the central source of pressurized operating fluid only the power required for its own operation, the power requirements of the various pumping units thus being independent of each other. Consequently, the power capacity of the central source needs be equal only to the sum of the power requirements of all of the pumping units, rather than the product of the number of pumping units and the power requirement of the unit demanding the most power, which is an important feature.

Another object is to provide pumping units the speeds of which are independently controllable so that the speed of each pumping unit is independent of that of every other.

unit in the system.

system capable of high pressure operation to reduce the sizes of the pumping units and the piping connecting them to the central station.

An additional object is to provide a fluid operated pumping system of the foregoing nature capable of utilizing clean crude oil as the operating fluid.

Still another object is to provide fluid operated rodtype pumping units which are sufliciently small to be suspended from the well heads of and to be contained entirely within the casings of the respective wells.

One more object in connection with the fluid operated pumping system of the invention is to provide fluid operated rod-type pumping units which may be utilized interchangeably with fluid operated bottom-hole pumping units, employing the same central source of operating fluid under pressure.

The present invention contemplates a fluid operated pumping system of the foregoing nature wherein each fluid operated rod-type pumping unit includes a reciprocable assembly comprising a pump piston within the well, an

Patented Oct. 24, 19 1 engine piston adjacent the surface and a rod string interconnecting the engine and pump pistons, and includes engine valve means adjacent the engine piston for alternately connecting an area of the engine piston to operating fluid pressure and exhaust pressure.

An important object of the invention is to provide a pumping unit of the foregoing nature which includes fluid operated means for counterbalancing the reciprocable assembly, preferablyapproximately of the weight of the reciprocable assembly being balanced by such fluid operated means.

Another object is to provide a pumping unit wherein the reciprocable assembly is counterbalanced by fluid operated means and wherein the operating fluid pressure is applied to the engine piston during the upward stroke of the reciprocable assembly only.

A further object of the invention is to provide fluid operated counterbalancing means which includes a counterbalance piston connected to the reciprocable assembly of the pumping unit in axial alignment with the engine piston thereof, and includes means for applying counterbalance fluid pressure to a downwardly facing area of the counterbalance piston.

An important object of the invention is to provide a fluid operated pumping system wherein the reciprocable assembly of each fluid operated rod-type pumping unit is displaced and counterbalanced hydraulically, but wherein the counterbalance piston of each unit forms part of a source of counterbalance fluid pressure.

More particularly. an object of the invention is to provide a fluid operated pumping system which includes a central counterbalance reservoir and in which the pumping units include compressors for pressurizing such reservoir.

Another object is to provide a fluid operated pumping system in which the compressor of each pumping unit includes the counterbalance piston thereof, such piston being reciprocable'in a counterbalance cylinder having adjacent its upper end an inlet valve means which communicates with the atmosphere and an outlet valve means which communicates with the counterbalance reservoir. Thus, as the counterbalance pistons of the various pumping units reciprocate in their cylinders, they alternately draw air thereinto and compress such air for delivery to the counterbalance reservoir, along with any counterbalance fluid leaking past the counterbalance pistons.

Another object of importance is to provide a fluid operated pumping system which includes fluid operated pumping means actuable by one of the pumping units in the system for pumping counterbalance fluid from the counterbalance reservoir into a counterbalance accumulator which is connected to the counterbalance cylinders of all of the pumping units. Thus, all of the pumping units operate to pressurize the counterbalance reservoir and to return counterbalance fluid leakage thereto, while only one of the pumping units operates the fluid operated pumping means for charging the counterbalance accumulator from the counterbalance reservoir.

Another object is to connect the fluid operated pumping means for charging the counterbalance accumulator in series with the engine valve means of the corresponding or master pumping unit. Thus, the fluid operated charging pump for the counterbalance accumulator operates in unison with the master pumping unit.

Another object is to provide a fluid operated pumping system of the foregoing nature having means for main taining predetermined pressures and liquid levels in the counterbalance reservoir and accumulator.

Another object is to provide a fluid operated pumping system wherein each pumping unit is provided with fluid operated means in series with and controlled by the engine valve means of such unit for displacing the unit vertically,

M whereby to properlyposition the pump piston thereof in its cylinder.

Another object of the invention is to provide each pumping unit with an engine valve means which includes a reciprocable engine valve and adjustable stops for limiting the travel of such engine valve in both directions. With this construction, the speed of the reciprocable assembly of each well unit is independently adjustable in either direction so that each pumping unit operates completely independently of all of the other pumping units.

Another object is to make each engine valve a differ-err ti al area engine valve reciprocable in an engine valve bore of uniform diameter and provided in one end thereof with a bore receiving a stationary piston which projects axially into one end of the engine valve bore.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the art in the light of this disclosure, may be attained with the exemplary embodiment of the invention described in detail hereinafter and illustrated in the accompanying drawings, in which:

FIG. 1 is a diagrammatic view illustrating an application of the fluid operated pumping system of the invention to two oil wells;

FIG. 2 is a semidiagrammatic view illustrating a portion of the pumping system of FIG. 1 on a larger scale and in more detail;

FIG. 3 duplicates FIG. 2, except that various components are shown in different operating positions;

I FIG. 4 is a top plan view of a fluid operated rod-type pumping unit of the invention incorporated in the pumping system of FIGS. 1 to 3;

FIG. 5 is a vertical sectional view taken along the irregular arrowed line 5*-'-5 of FIG. 4;

FIG. 6 is a downward continuation of FIG. 5;

(FIG. 7 is a downward continuation of FIG. 6;

FIG. 8 is a downward continuation of FIG. 7;

FIG. 9 is an enlarged, fragmentary vertical sectional view taken along the arrowed line 99 of FIG. 4;

FIG. 10 is an enlarged, fragmentary vertical sectional view taken along the arrowed line 19-10 of FIG. 4;

FIGS. ll, 12 and 13 are horizontal or transverse sectional' views respectively taken along the arrowed lines 11 -11, 12-12 and 13'-13 of FIG. 9; and

FIG. 14 is a semidiagrammatic view illustrating an alternative orientation of a counterbalance accumulator constituting one of the components of the pumping system of-FIGS. 1 to 3 of the drawings.

General structure of pumping system Referring particularly to FIG. 1 of the drawings, and incidentally to FIGS. 2 and 3 thereof, the numerals 2!? and 22 designate oil wells to be pumped by the fluid operated pumping system of the invention, it being understood that while two wells are shown, this number may be varied. The wells 20 and 22 are provided with casings 24 and 26 respectively, surmounted by casing heads 28 and 30, respectively. Suspended from the respective casing heads 28 and 3t and disposed within the corresponding casings 24 and 26 are inner casings 32 and 34.

Surrnounting the respective casing heads 28 and 30 are well heads 36 and 38 respectively supporting production tubings 4t) and 42 within the respective casings 32 and 34. Production fluid discharge lines 44 and 46 are connected to the well heads 36 and 38 in communication with the production tubings 40 and 42, respectively. Gas discharge lines 48 and 50 are connected to the casing heads 28 and 30 in communication with annular spaces around the production tubings 40 and 42, respectively, and gas discharge lines 52 and 54 are connected to the casing heads 28 and 30 in communication with annular spaces around the casings 32 and 34, respectively.

Installed in the respective Wells 20 and 22 are rod-type fluid operated pumping units 56 and 58 respectively car- 4.. ried by pumping unit heads 60 and 62 mounted on the respective well heads 36 and 38. As will be discussed in more detail hereinafter, the pumping unit heads 6%} 62 are vertically movable relative to the well heads 36 and 38.

The pumping units 56 and 58 respectively include pump sections 64 and 66 located adjacent the lower ends of the production tubings 4i) and 42, these pump sections respectively including pump pistons 68 and '76 reciprocabie in pump cylinders 72 and 74. The pumping units 56 and 58 also respectively include engine sections 76 and 78 and counterbalance sections 81 and 82 carried by pumping unit heads 60 and 62 within the upper ends of the production tubings 4d and 42. The engine sections 76 and 78 respectively include engine pistons 34 and 86 reciprocable in engine cylinders 38 and 96. The engine pistons 84 and 86 are connected to the pump pistons 68 and 70, respectively, by rod strings 92 and $4 which are disposed in the production tubings 4i and 42, and which are provided at their upper ends with polished rods $6 and 98 extending through the lower ends of the engine cylinders 88 and 91). The counterbalance sections 86 and 82 respectively include counterbalance pistons 16% and 1152 reciprocable in counterbalance cylinders 18% and 136 which are axially aligned with the engine cylinders 88 and 90, respectively. The counterbalance pistons 11th and 102 are connected to the engine pistons 84 and 86, 'respectively, each counterbalance piston thus being connected to a reciprocable assembly comprising the corre sponding engine piston, rod string and pump piston.

The aforementioned reciprocable assemblies of the pumping units 56 and 58 are reciprocated by alternately applying operating fluid pressure and exhaust pressure to downwardly facing areas 108 and 110 of the engine pistons 84 and 86, respectively. When the operating fluid pressure is applied to the areas 108 and 110, the reciprocable assemblies move upwardly, FIG. 2, and when the exhaust pressure is applied thereto, these assemblies move downwardly, FIG. 3, the pump pistons 68 and 70 pumping well fluid upwardly through the production tubings 40 and 42 to the surface during the upward strokes, the downward strokes, or both strokes, of the reciprocable assemblies. The alternate application of operating fluid pressure and exhaust pressure to the areas 108 and 110 isfeife'ct'ed by engine valve means 112 and 11d, respectively, which are carried by the pumping unit heads 60 and '62, respectively, the engine valve means 112 being connected to the area 108 by a passage 115, FIGS. 2 and 3, in the pumping unit head 60, and the engine valve means 114 being connected to the area 1 10 by a similar passage which is not shown in the drawings. The two engine valve means 112 and 114 are connected to an operating fluid line 116 by branch lines 118 and 120, respectively, and to an exhaust or return line 122 for spent operating fluid by branch lines 124 and 126. As will be described in more detail hereinafter, the engine valve means 112 alternately connects the passage to the branch lines 118 and 124, the engine valve means 114 alternately connecting the corresponding passage of the pumping unit 58 to the branch lines 121) and 126.

The operating fluid line 116 is connected to the outlet of an operating fluid supply pump 128, which may be a conventional triplex pump of the type normally used in a fluid operated, multiwell pumping system utilizing bottom hole pumping units. The inlet of the pump 128 is connected, by an inlet line 131), to an operating fluid supply reservoir 132. The exhaust or return line 122 for spent operating fluid is connected to the reservo r 132, which is maintained at the exhaust pressure.

The reciprocable assemblies of the pumping units 56 and 58 are counterbalanced by connecting downwardly facing areas 134 and 136 of the respective counterbalance pistons 100 and 162 to a counterbalance fluid pressure line 138 through branch lines 140 and 142 and passages in the pumping unit heads 60 and 62, this passage in the pumping unit head 60 being shown in FIGS. 2 and 3 and being designated by the numeral 143. The pressure line 138 leads to a source 144 of counterbalance fluid under pressure. The counterbalance fluid pressure provided by the source 144 and the areas 134 and 136 of the counterbalance pistons 100 and 102 are so selected that approximately 90% of the weights of the rod strings 92 and 94 are balanced, which provides the desired downstroke speeds for the reciprocable assemblies of the pumping units 56 and 58 when the areas 108 and 110 of the engine pistons 84 and 86 are connected to exhaust pressure. The engine piston areas 168 and 110 and the operating fluid pressures applied thereto are so selected as to move the corresponding reciprocable assemblies upwardly at the desired speeds in opposition to the resistance to upward movement provided by the unbalanced weights of the assemblies, the weights of the production fluid columns, and the effects of mechanical and fluid friction.

Since, in practice, the pump sections 64 and 66 may be set at different depths, the weights of the rod strings 92 and 94 may differ, in which case the reciprocable assemblies of the pumping units 56 and 58 cannot be counterbalanced equally. In such a situation, the counterbalance fluid pressure provided by the source 144 is preferably maintained at approximately 90% of that required to fully balance the weight of the lightest rod string. Heavier rod strings are then balanced to lesser extents. These considerations are applicable to rod string weight variations resulting from diflerences in rod string diameter, as well as differences in rod string length.

Differences in the pumping loads which must be overcome by the various pumping units 56 and 58 are taken care of by maintaining the operating fluid pressure provided by the pump 128 at a value sufliciently high to provide the desired operating speed for the pumping unit having the highest pumping load. The engine valve means of the other pumping unit or units are then adjusted, in a manner to be described, to throttle the flow of operating fluid under pressure therethrough as required to provide the desired operating speeds with lighter pumping loads.

Preferably, the engine sections 76 and 78 of the pumping units 56 and 58 are operated hydraulically by utilizing as the operating fluid a liquid such as clean crude oil. The counterbalancing of the pumping units is accomplished by a hydraulic-pneumatic counterbalancing means which will now be considered.

The counterbalance fluid pressure source 144 contains a liquid, such as oil, and a gas, such as air, and includes an accumulator 146 and a reservoir 148 in series. The counter-balance sections 80 and 82 of the pumping units 56 and 58 act as compressors which maintain the pressure in the counterbalance reservoir 148 at a value intermediate atmospheric pressure and the pressure required for counterbalancing, the counterbalance reservoir being connected to the counterbalance sections 80 and 82 by a counterbalance return line 156 and branch lines 152 and 154, respectively. The pressure in the counterbalance accumulator 146, which is connected to the counterbalance pressure line 138, is maintained at the value required for counterbalancing by a fluid operated pumping means or charging pump 156 connecting the counterbalance reservoir 148 to the accumulator.

Considering the manner in which the counterbalance sections 80 and 82 act to pressurize the counterbalance reservoir 148, the counterbalance section 89, as best shown in FIGS. 2 and 3 of the drawings, is provided with inlet and outlet check valves or check valve means 158 and 168 which communicate with the upper end of the counterbalance cylinder 104. The inlet check valve 158 communicates with the atmosphere and the outlet check valve 160 communicates with the branch line 152 leading to the counterbalance return line 150. As

3 will be apparent, when the counterbalance piston moves downwardly, air is drawn into the counterbalance cylinder 1114 through the inlet check valve 158. During upward movement of the counterbalance piston 100, the

air in the counterbalance cylinder 184 thereabove is com-' pressed and is discharged through the outlet check valve into the branch line 152 and the counterbalance return line 150 leading to the counterbalance reservoir 148, thereby pressurizing said reservoir. In addition to delivering compressed air to the counterbalance reservoir 148 during each upward stroke, the counterbalance piston 100 also delivers to the counterbalance reservoir any of the oil in the counterbalancing system which may have leaked upwardly past the counterbalance piston 100. Thus, the counterbalance section 80 of the pumping unit 56 acts both as a compressor for delivering compressed air to the counterbalance reservoir 148, and acts also as a leakage return pump which automatically conveys back to the counterbalance reservoir 148 any leakage occurring in the counterbalance section, which are important features of the invention. The counterbalance section 82 of the pumping unit 56 operates as a compressor and a leakage return pump in precisely the same manner, being connected to the counterbalance reservoir 148 through the branch line 154 and the counterbalance return line 150.

Referring to FIGS. 2 and 3, the charging pump 156 includes aligned engine and pump cylinders 162 and 164 in which engine and pump pistons 166 and 168 are reciprocable, respectively, these pistons being interconnected. One end of the engine cylinder 162 is connected to the passage 115 controlled by the engine valve means 112 of the pumping unit 56 by a line 170 and a branch passage 172 in the pumping unit head 60. The other end of the engine cylinder 162 is connected to the counterbalance reservoir 148 through a main line 174 and a branch line 176.

The pressure in the counterbalance reservoir 148 is intermediate that in the operating fluid reservoir 132 and that provided by the operating fluid pump 128, Consequently, as the engine valve means 112 alternately connects the passage 115 to the branch line 118 leading to the operating fluid pump 128 and the branch line 124 leading to the operating fluid reservoir 132 to produce reciprocatory movement of the reciprocable assembly of the pumping unit 56, the engine valve means 112 simultaneously alternately connects the passage 172 to the branch lines 118 and 124 so as to produce reciprocatory movement of the engine and pump pistons 166 and 168 of the charging pump 156. Thus, the charging pump 156 and the engine section 76 of the pumping unit 56 are connected in series with the engine valve means 112 and in parallel with each other. As will be apparent, when the operating fluid pressure is applied to the engine piston 166, the engine and pump pistons 166 and 168 move upwardly, as viewed in FIGS. 2 and 3, and when the exhaust pressure in the operating fluid reservoir 132 is applied to the engine piston 166, the engine and pump pistons 166 and 168 move downwardly. Thus, the engine valve means 112 of the pumping unit 56, in addition to producing reciprocatory movement of the reciprocable assembly of this pumping unit, also produces reciprocatory movement of the engine and pump pistons 166 and 1680f the charging pump 156 because of the series connection between the charging pump and the engine valve means 112, which is an important feature of the invention.

The charging pump 156 includes inlet and outlet check valves or check valve means 178 and 180 which communicate with the pump cylinder 164, the inlet check valve 178 being connected to the main line 174 from the counterbalance reservoir 148, and the outlet check valve 180 being connected to the counterbalance accumulator 146 by a line 182. Thus, as the engine and pump pistons 166 and 168 are reciprocated under the control of the '7 engine valve means 112 of the pumping unit 56 in the mannerhereinbefore described, fluid is pumped from the counterbalance reservoir 148 to the counterbalance accumulator 146 to maintain the desired counterbalancing pressure within the accumulator.

The line 174 communicates with the counterbalance reservoir 148 at an intermediate level so that the charging pump 156 pumps only liquid from the counterbalance reservoirinto the counterbalance accumulator 146 as long as the liquid level is above the intermediate level. How ever, if the liquid level in the counterbalance reservoir 148 is below the point at which the line 174- communicates therewith, air, or a mixture of air and oil, is pumped from the counterbalance reservoir into the counterbalance accumulator 146.

From the foregoing, it will be apparent that the charging pump 156 operates in unison with the pumping unit 56 to which it is connected, but that it may draw air and liquid from each of the pumping units 56 and 58 by way of the counterbalance reservoir 143. As hereinbefore explained, the counterbalance sections 80 and $2 of the pumping units 56 and 58 act as first stage compressors and as leakage return pumps.

If the amount of air delivered to the counterbalance reservoir 148 by the counterbalance sections 83 and 82 of the pumping units 56 and 58 is in excess of the amount necessary to maintain constant pressure in the counterbalance reservoir, any excess is discharged to the atmosphere through a relief valve 184. An excess pressure developed in the counterbalance accumulator 146 is dissipated by a relief valve 186 which is connected to the operating fluid reservoir 132 by a line 138, the relief valve 186 preferably being located at a level approximately midway between the upper and lower ends of the accumulator 46. In order to offset any loss of liquid from the counterbalance system, a line 190 preferably leads from the outlet of the supply pump 128 to the counterbalance reservoir 148, a restrictor 192 being interposed in this line to permit liquid from the pump 12% to bleed into the counterbalance reservoir at a low rate. If the rate of bleeding of liquid from the supply pump 128 to the counterbalance reservoir 148 is set at a value higher than required to overcome liquid leakage from the counterbalance piston, then this excess, together with the total leakage returned by the counterbalance pistons 153i} and 13 2, is transferred to the counterbalance accumulator 146 by the charging pump 156 since the inlet of the charging pump communicates with the reservoir I48 below the liquid level therein under such conditions. This will tend to raise the liquid level in the counterbalance accumulator 146 above the level at which the relief valve 136 communicates therewith so that, whenever the liquid level in the accumulator 146 is above the relief valve 186 and the pressure therein is above the setting of this relief valve, the excess liquid will be discharged into the reservoir 132. Also, if the amount of air pumped into the counterbalance accumulator 146 from counterbalance reservoir 148 exceeds the total leakage of air from the counterbalance system, the pressure in the counterbalance accumulator will be increased to a value above the setting of the relief valve 186 and such excess air will also be discharged into the operating fluid reser voir 132. The setting of the relief valve 1% is such as to maintain in the counterbalance accumulator 146 the pressure desired for counterbalancing, as hereinbefore discussed.

Preferably, the counterbalance accumulator 146 is a cylinder which maybe positioned either horizontally or vertically, the vertical orientation thereof being shown in FIGS. 2 and 3 of the drawings. The counterbalance pressure line 138 is connected to the lower end of the accumulator 146 and the relief valve 186 is connected thereto approximately midway between the lower and upper ends thereof. The charging pump 156 is mounted on the accumulator 146 with the inlet and outlet check valves 178 sunsets l8 and 180 so oriented that they areseated by gravity. The outlet check valve 18!) is connected to the upper end of the'counterbalance accumulator 146'and is located at thehighest point in the system so that the charging pump 156' will discharge air first, followed by liquid, which results in an infinite compression ratio and permits the charging pump to produce any desired pressure.

Referring to FIG. 14, when the counterbalance accumulator 146 is oriented horizontally, the various connections thereto are rearranged so that the counterbalance pressure line 138 again communicates with the bottom of the accumulator to deliver liquid only to the counterbalance sections and 82 of the pumping units 56 and 5S and so that the relief valve 186 is again located approximately midway between the upper and lower ends of the accumulator. The output check valve 180 communicates with the accumulator 146 at the same point as for the vertical orientation of the accumulator, but the inlet and outlet check valve assembly is connected to the pump cylinder 164 of the charging pump 156 by an elbow 194 which again orients the inlet and outlet check valves 178 and 180 so that they seat by gravity and so that the outlet check valve 18% is at the highest point in the system.

As hereinbefore indicated, each of the pumping units 56 and 58 is adjustable vertically by fluid operated means to be described so as to properly position the pump piston thereof in the corresponding pump cylinder. Considering this fluid operated means of the pumping unit 56- with reference to FIGS. 2 and 3 of the drawings, the well head 36 is provided with an upwardly projecting tubular extension 2G2 slidably receiving the counterbalance section 88 of the pumping unit 56. The pumping unit head 60' is provided with a depending cylindrical skirt 204 which is telescoped over the well head extension 202 in sliding engagement therewith. This structure provides the pumping unit head '60 with a downwardly facing annular area 206 which is connected to the passage controlled by the engine valve means 112 by a passage 208 in the head 60, the passage 208 being controlled by a manually operable valve 210.

As will be apparent, if the valve 210 is opened when the engine valve means 112 connects the passage 115 to the line 116 leading to the operating fluid supply pump 128, operating fluid pressure is applied to the area 2116 to lift the pumping unit 56. On the other hand, if the valve 216 is opened when the engine valve means 112 connects the passage 115 to the line 124 leading to the operating fluid reservoir 132, the pumping unit 56 is lowered in the well. Thus, since this fluid operated means for varying the vertical position of the pumping unit 56 is connected in series with the engine valve means 112, the direction of vertical movement of the pumping unit is determined by the engine valve means 112, which is an important feature. The pumping unit 58 is vertically movable in an identical manner.

The purpose of the foregoing vertical adjustment of each pumping unit is to so position the pump piston thereof relative to its pump cylinder that the stroke of the pump piston relative to the pump cylinder matches the stroke of the corresponding engine piston relative to its engine cylinder. This vertical adjustment must be made under load to compensate for the effects of shortening and lengthening of the corresponding rod string under load. After the adjustment has been made, the valve 219 of the pumping unit being adjusted is closed to lock the pumping unit in place hydraulically. Supplementary mechanical locking means will be considered hereinafter.

The foregoing completes a general description of the structure of therod-type fluid operated pumping system of the invention. The general or over-all operation of the pumping system will now be discussed and thereafter, in a consequent section of this specification, the structure and operation of one of the pumping units, viz., the pumping unit 55, will be considered in detail.

Q General operation of pumping system When the rod-type fluid operated pumping system of the invention is in operation, the pump 12% supplies operating fluid under pressure to all of the pumping units in the system, such as the pumping units 56 and 53, spent operating fluid from all of the pumping units being returned to the operating fluid reservoir 132. The engine valve means 112 and 114 of the pumping units 56 and 58 alternately connect the downwardly facing areas 108 and 110 of the engine pistons 84 and 86 to the operating fluid supply pump 128, HQ 2, and the operating fluid reservoir 132, FIG. 3, to produce reciprocatory movement of the reciprocable assemblies of these pumping units, whereby the pump sections 64 and 66 thereof pump production fluid from the wells 21) and 22 upwardly through the production tubings 4i and 42 into the production fluid discharge lines 44 and 46.

The rod strings 92 and 94 of the pumping units 56 and 58 are counterbalanced by applying the counterbalance fluid pressure in the counterbalance accumulator 146 to the downwardly facing areas 134 and 136 of the counterbalance pistons flflii and 1132. As hereinbefore indicated, the relief valve 186 maintains the counterbalance fluid pressure in the accumulator 146 at a value such as to balance approximately 90% of the weight of the lightest rod string. 1

Thus, the pumping units 56 and 58 are hydraulically counterbalanced at all times, and power is applied to the engine pistons 34 and 36 only during upward movement of the reciprocable assemblies of the pumping units. The downward strokes of the reciprocable assemblies are produced by gravity at speeds dependent upon the extents to which the weights of the rod strings are counterbalanced and, as will be discussed hereinafter, on the extents to which the engine valve means 112 and 114 throttle return flow of spent operating fluid to the operating fluid reservoir 132.

The counterbalance sections 80 and 82 of the pumping units 56 and 58 act as compressors for pressurizing the counterbalance reservoir 148 and act as leakage pumps for returning to the counterbalance reservoir any liquid leaking past the counterbalance pistons 100 and 102. More specifically, the counterbalance pistons 100 and 102 draw air at atmospheric pressure into the counterbalance cylinders 104 and 106 during the downward strokes of these pistons, such air being compressed and delivered to the counterbalance reservoir 148 during the upward strokes of the counterbalance pistons, along with any liquid leaking past the counterbalance pistons.

The pumping unit 56, which may be regarded as a master pumping unit, controls the charging pump 156, which pumps liquid and/or air from the counterbalance reservoir 148 into the counterbalance accumulator 146. The charging pump 156 is connected in series with the engine valve means 112 so that the piston assembly of the charging pump reciprocates in unison with the reciprocable assembly of the master pumping unit 56. Thus, the counterbalance sections of the various pumping units act as compressors for pressurizing the counterbalance reservoir 148 and act to return leakage thereto, while the master pumping unit operates the charging pump 156 for pressurizing the counterbalance accumulator 146 to the desired counterbalancing pressure with fluid derived from the counterbalance reservoir.

If it is necessary to adjust the vertical position of any of the pumping units in the corresponding well, this is accomplished by opening the corresponding valve 210 with the corresponding engine valve means in the proper position, each pumping unit being lifted when its engine valve means connects the corresponding valve 210 to the operating fluid supply pump 128, and being lowered when its engine valve means connects the corresponding valve 210 to the operating fluid reservoir 132.

Thus, in each pumping unit, the engine valve means 1G performs the dual function of producing reciprocatory movement of the corresponding reciprocable assembly and of producing upward or downward movement of the pumping unit. The engine valve means of the master pumping unit performs the additional function of controlling the operation of the charging pump 156.

Structure and operation of pumping unit 56 The rod-type fluid operated pumping unit 56 is illustrated in detail in FIGS. 4 to 13 of the drawings, the reference numerals applied to various components of this pumping unit in FIGS. 1 to 3 of the drawings also being applied to these components in FIGS. 4 to 13 thereof. In view of the general description of the pumping unit 56 presented previously herein, it will be necessary to consider only a few structural features of this pumping unit hereinafter in connection with FIGS. 4 to 13 of the drawings.

The engine piston 84 of the pumping unit 56 is simply a rod which is threaded at its upper end into the counterbalance piston and which projects axially from the counterbalance cylinder 104 into the engine cylinder 88 through a sealing or packing assembly 220. The engine cylinder 88 is an enlarged chamber into which the engine piston 84 projects so that the downwardly facing area 108 of the engine piston is acted on by the pressure existing in the engine cylinder, this pressure being alternated between the operating fluid pressure and the exhaust pressure by the engine valve 112, as will be discussed hereinafter. The polished rod 96 is threaded into the lower end of the engine piston 84 and projects downwardly through a sealing assembly 222 at the lower end of the engine cylinder 88, the lower end of the polished rod being connected to the rod string 92.

The counterbalance cylinder 104 comprises a liner onto which is shrunk a tube 224, the upper end of this tube being disposed in a bore 226 in the pumping unit'head 60. Threaded into the upper end of the tube 224 is a flanged fitting 228 which supports the cylinder 104 and the tube 224 shrunk thereonto and which is bolted, or otherwise secured, to the head 60. The fitting 228 carries the inlet and outlet check valves 158 and 160 and has the branch counterbalance return line 152 connected thereto in communication with the outlet check valve. An axial bore 230 places the inlet and outlet check valves 158 and 160 in communication with the interior of the counterbalance cylinder 164. The counterbalance piston 100 is provided at the upper end thereof with a tapered extension 232 which is inserted into the bore 230 as the reciprocable assembly of the pumping unit 56 approaches the upper end of its stroke. As the tapered extension 232 is inserted into the bore 230, flow of compressed air and leakage oil from above the piston into the bore 230 is retarded to provide a dashpot action for decelerating the reciprocable assembly of the pumping unit 56 as it approaches the upper end of its stroke. A similar dashpot action decelerates the reciprocable assembly of the pumping unit 56 as it approaches the lower end of its stroke, the structure producing this dashpot action being described hereinafter.

Threaded into the lower end of the tube 224 shrunk onto the counterbalance cylinder 194 is a coupling 234 into which the engine cylinder 8%; is threaded, the sealing assembly 220 being provided with a flanged upper end 235 which is clamped between the upper end of the coupling 234 and the lower end of the counterbalance cylinder 104. The sealing assembly 222 is threadedly connected to the lower end of the engine cylinder 88. Thus, the structure comprising the counterbalance cylinder 104, the tube 224 shrunk thereonto, the sealing assembly 220, the engine cylinder 8-8 and the sealing assembly 222 are all suspended from the pumping unit head 60 by means of the fitting 228.

The counterbalance cylinder 104 and the tube 224 shrunk thereonto cooperate to provide parts of the passage swans engine cylinder 38, parts of the passage 143 for connecting the line 146 leading to the counterbalance accumulator 146m the counterbalance cylinder 104 below the counterbalance piston lllll, and parts of two control passages for controlling a reciprocable engine valve 236 forming part of the engine valve means 112. More particularly, the exterior of the counterbalance cylinder 104 is provided with twelve circumferentially spaced, longitudinal grooves therein which are converted into twelve separate channels by the tube 224 shrunk onto the counterbalance cylinder 164. Of these twelve channels, three, identified by the numeral 238, form parts of the passage 115 leading from the engine valve means 112 to the engine cylinder 88, as best shown in FIGS. 9 and 11 to 13., The channels 238 communicate at their upper ends with radial ports 246, FIGS. 9 and 11, through the outer tube 224, these ports communicating with. an internal annular channel 242 in the head oil. Qommunicating with the channel 242 are a port 244 leading to the engine valve means 112 and a port 246 forming part of the passage 172 communicating with the l ne 170 leading to the engine section of the charging pinnp 156. Referring to FIG. 7, the channels 238 communicate at their lower ends with longitudinal grooves 248 through the flanged upper end 235 of the.

sealing assembly 226, the grooves 248 communicating with an annular space between the sealing assembly 22a and the coupling 234. The lower end of this annular space communicates with the engine cylinder 88. Thus, communication between the engine cylinder -88, the engine valve means 112 and the line 170 leading to the charging pump 156 is established.

'Seven of the twelve longitudinal channels. between the counterbalance cylinder ltid and the tube 224 form parts of the passage .143 leading to the lower end of the counterbalance cylinder 164 below the counterbalance piston Hill. These seven channels are designated by the numeral 259 in FIGS. 7, 9, l2 and 13 of the drawings, the showings in FIGS. 7 and 9 being phantom showings. The upper ends of the channels 259 communicate with radial ports 252 through the tube 224, as shown in FIGS. 9 and 12. The ports 252, as shown in FIG. 9, communicate with an internal annular channel 254 in the head 65, this channel communicating with a port 256 leading to the branch counterbalance line 140. The channels 250 communicate at their lower ends with radial ports 258, H68. 7, l2 and 13, in the counterbalance cylinder Hi4 near the lower end thereof. Thus, the counterbalance cylinder 1M below the counterbalance piston tee is connected to the branch counterbalance line 146 via the system of channels and ports just described.

, Referring to FIG. 7 of the drawings, it will be noted that the lower end of the counterbalance piston 130 is provided with a tapered extension 259 and that the ports 253 at the lower ends of the channels 25s are located adjacent the upper, larger end of this tapered extension when the counterbalance piston is at the lower end of its travel. As the smaller end of the tapered extension 259 passes the ports 2% and moves downwardly therebelow, the area of the flow passage from beneath the counterbalance piston to the ports 258 progressively diminishes. Thus, a dashpot action serving to decelerate the reciprocable assembly of the pumping unit 56 as it approaches the lower end of its travel results.

The remaining two of the twelve longitudinal channels between the counterbalance cylinder 164 and the tube 224 shrunk thereonto are identified by the numerals 260 and 262, respectively, and serve as control channels for the engine valve 236. The control channel 26% communicates at its lower end, PEG. 7, with a radial port 262 in the counterbalance cylinder 1% above the lowermost position of the counterbalance piston 1%. Thus, the pressure in the control channel 260 is equal to the counterbalancing pressure in the counterbalance accumulator 146 when the counterbalance piston li o-is above the port 252, and drops 12 to or below" atmospheric pressure as the counterb-almice piston. moves. downwardly below this port, being intermediate atmospheric pressure and the pressure in thecounterbalance reservoir. 148 as the piston ltlll moves upwardly toward the port 262. The upper end of the control channel 264) communicates with a radial port 264, FIG. 9, in the tube 224, this port communicating with an internal annular. channel266 inthe pumping unit head so. The channel 266 communicates. with a port 268 leading from the engine valve means 112 through a check valve 269 which. permits flow away from the engine valve means.

only.

Similarly, asshown in FIGS. 9 and 13, the channel 262.

communicates atits lower. endwith a radial port 270 in the counterbalancecylinder 104. The port 270 islocated below the uppermost position of the counterbalance piston.

19% so that the pressure in this port ranges from a maxi.- mum equal to the c-ounterbalancing pressure when the counterbalance. piston isthereabove to a minimum equal to. or less than atmosphericas the counterbalance piston.

moves downwardly therepast, the pressure at the port 270 approaching that in the counterbalance reservoir 143 as the piston 160 moves upwardly theretoward. The control.

channel 262 communicates at its upper end with a radial port 272 in the outer. tube 224, the port 272 communicating with an internal annular channel 274 in the head. 60.

valve 236 being reciprocable between upper and. lower.-

positionsin the bore232. The liner 28d is provided with an external annular channel 284 therein which communicates with the branch operating fluid exhaust line 124 so that the exhaust pressure is always present in this channel.

The liner 2801s providedwithradial ports 2&6 communieating at their outer ends with the channel 284 and at their inner endswith an internal annular groove 288, this groove also communicating with a wide internal annular channel29ll in the liner 280- which extends all the way to the upper end thereof.

Below the channel 284 is an external annular channel 292 in the liner 239, this channel communicating with a port 294 in the housing 278. The port 294 registers with the previously described port 244 forming part of the passage leading to the engine cylinder 8?. Radial ports296 in the liner 280 connect the channel 292 therein to an internal annular groove 298 therein.

Below the channel 22 in the liner 2% is an externalannular. channel 3.00 therein which constantly con1muni-;

cates with the branch operating fluid pressure line 118.

The channel 30.0. communicates with radial ports 392 which, in. turn, communicate with an internal annularchannel 305. inthe liner 280 through an internal annular groove 3% therein.

The. liner 280 is provided with external annular grooves 306 and 3.68 respectively communicating with ports 310- and 312. in the valvehousing 278, the ports are and 312 respectively communicating with the ports 276 and 268 leading to the control channels 262 and 260; respectively.

The grooves-30.6 and.3tl8 respectively communicate with" radial-ports- 31.4 and-316 through the liner 280, the ports 314 and 316 respectively communicating with internal annular grooves 318 and 32th. in the liner.

The engine valve 236 is provided therein with an an:-

nular. channel. 322 which. bridges the grooves 298 and 3% when the. valve is in its lower position so as to apply the operating fluid pressure to the downwardly facing area 1630f the engine piston 34, thereby producing the upward stroke of the reciprocable assembly of the pumping unit 56.

At the same time,.the valve 236 applies the operating fluid pressure to'the engine piston 166 or" the charging'pump 156 to produce the working stroke of the charging pump. When the valve 236 is in its upper position, the channel 322 bridges the grooves 298 and 288 in the liner 280, whereby exhaust pressure is applied to the downwardly facing area 108 of the engine piston 84 and to the engine piston 166 of the charging pump 156 to produce the downward stroke of the reciprocable assembly of the pumping unit 56 and the return stroke of the charging pump. Thus, when the valve 236 is in its lower position, it produces the upward stroke of the pumping unit 56 and the working stroke of the charging pump 156, and when this valve is in its upper position, it produces the downward stroke of the pumping unit and the return stroke of the charging pump.

The valve 236 is provided with V-shaped throttling notches 324 therein at the ends of the annular channel 322. These notches cause the valve 236 to connect the groove 2% to the grooves 288 and 304 slowly as the valve moves from one of its positions to the other, thereby applying the operating fluid and exhaust pressures to the engine and charging pump pistons 84 and 166 gradually to avoid hydraulic shock. These throttling notches perform another function which will be considered hereinafter.

Considering the manner in which the engine valve 236 is moved between its upper and lower positions, this valve is a difierential-area valve having two upwardly.

facing areas 326-and 328 and a downwardly facing area 330, each of the two upwardly facing areas being substantially equal to one-half the downwardly facing area. The upwardly facing areas 326 and 328 are formed by providing the upper end of the valve 236 with an axial bore 332 receiving a stationary piston or plunger 334 which projects axially downwardly into the engine valve bore 282. The lower end of the bore 332 forms the upwardly facing area 326, while the annular area of the upper end of the valve 236 around the bore 332 forms the upwardly facing area 328, the areas 326 and 328 being separated by the piston 334 in either position of the valve.

The area 326 of thervalve 236 is constantly exposed to the operating fluid pressure present in the annular channel 300 through the ports 302, the groove 304, the channel 305, radial ports 336 in the valve, and an axial passage 338 therein. The area 328 of the engine valve 236 is constantly exposed to the exhaust pressure present in the annular channel 284 through the ports 286, the annular groove 288 and the annular channel 230. Thus, the engine valve 236 is continuously biased downwardly toward its lower position by a force equal to the product of the operating fluid pressure and the area 326131115 the product of the exhaust pressure and the area 328.

The counterbalancing pressure maintained in the counterbalance accumulator 146 is sufficiently high that application of this pressure to the downwardly facing area 330 of the engine valve 236 results in an upward forcegreater than the constant downward force hereinbefore discussed, whereupon the engine valve moves upwardly into its upper position. The counterbalancing pressure is applied to the area 330 by the counterbalance piston 100 in a manner which will be described in the next paragraph. However, other pressures developed in the counterbalance cylinder 164 and applied to the area 330, such as atmospheric pressure, the pressure in the counterbalance reservoir 148, or a pressure intermediate these values developed as air is compressed in the counterbalance cylinder 104 during upward movement of the counterbalance piston 100, are insuificient to produce upward movement of the engine valve 236.

Considering the manner in which the counterbalance piston 100 controls the movement of the engine valve 236, it will be assumed that the engine valve is in its lower position, as shown in FIG. 9 of the drawings, so that the reeiprocable assembly of the pumping'unit 56, including the counterbalance piston 100, is moving upwardly. As

the. counterbalance piston 100 approaches the upper end of its stroke, it moves upwardly past the port 270, whereupon the counterbalancing pressure beneath the counterbalance piston is applied to the area 330 of the engine valve 236 through the port 270, the control channel 262, the port 272, they annular channel 274, the port 276, the

check valve 277, the port 310, the annular groove 306, the ports 314, the annular channel 318, radial ports 340 in the engine valve, and an axial passage 342 therein. The resultant movement of the engine valve into its upper position connects the downwardly facing area 108 of the engine piston 84 to exhaust pressure to produce the downward stroke of the pumping unit 56, and connects the engine piston 166 of the charging pump 156 to exhaust pressure to produce the return stroke of the charging pump.

The engine valve 236 remains in its upper position until the pumping unit 56 approaches the lower end of its travel, at which time the counterbalance piston 100 moves downwardly below the port 262 communicating with the control channel 260. When this occurs, atmospheric pressure within the counterbalance cylinder 104 is applied to the downwardly facing area 330 of the engine valve 236 through the port 262, the control channel 260, the port 264, the annular channel 266, the port 268, the

check valve 269, the port 312, the annular groove 308,

the ports 316, and the annular groove 320, the lower end of the valve 236 being above the annular groove 320 when the valve is in its upper position. Consequently, the engine valve 236 moves downwardly into its lower position to connect the downwardly facing area 108 of the engine piston 84 and the engine piston 166 of the charging pump 156 to the operating fluid pressure, thereby initiating the upward stroke of the pumping unit 56 and the working stroke of the charging pump.

The engine valve 236 is a two-speed valve, the initial valve movement in each direction being at high speed and being initiated by the counterbalance piston in the manner hereinbefore described. The high speed movement of the engine valve 236 in each direction con--' tinues as the channel 322 disconnects the groove 298 from the corresponding one of the grooves 288 and 304, the high speed in each direction being reduced to a final slow speed as the channel 322 begins to place the groove 298 in communication with the other of the grooves 288 and 304 through the V-shaped throttling notches at the toward its upper position, the engine valve moving upwardly at high speed as long as the channel 344 com-1 municates with the groove 313. Once the channel 344 moves upwardly out of the communication with the groove 318, communication between the area 330 of the engine valve 236 and the counterbalance cylinder 104 below the counterbalance piston 100, by way of the control channel 262, is cut oflf. At this point, an eX,--

ternal annular channel 346 in the engine valve 236 registers with the annular channel 305, which is always filled with operating fluid under pressure through the groove 364, the radial ports 302 and the channel 300. The. lower end of the channel 346 communicates with a restricted helical groove or thread 348 in the exterior of the engine valve, the lower end of the thread 348 com- -municating with the axial passage 342 through an external annular groove 350 and radial ports 352 in the engine valve. Thus, under these conditions, the operating fluid pressure is applied to the area 330 of the engine valve 236 through the channel 346, the thread 348,

15. thezgroove-350, the parts 352 and the. axial passage 342.. Consequently, the engine valve continues its upward movement into its upper position, but at areduced speed, determined by the resistance offered by thethread 348. This means of communication between the area 330 of the: engine valve and the operating fluid pressure also. serves. as a hydraulic lock for maintaining the engine valve in its upper position until such time as the counterbalancepiston 100 moves downwardly to thelower end of. its travel to apply atmospheric pressure to. the. area 3.30. of the engine valve.

As'the engine valve 236 moves downwardly in response tothe application of atmospheric pressure to the area 330 thereof, the lower end of the engine valve eventually covers the annular groove 329, thereby cutting off communication by way of'the control channel 260, between the. area 338 of the enginevalve and the atmospheric pressure; existinginthe counterbalance cylinder: 104 above the. piston. 100. This terminates the high speed doWn-. ward movement of the engine valve.. Thereafter, the downward movement of the engine valve iscontinued at a. reduced speed by applying theexhaust pressure to the area 330. thereof through the axial passage 342, the radial ports 352, the groove 350, arestrictedv helical groove on thread 354 in. the enginevalve;,a channel. 358 therein, an:internal annular groove 360-inthe liner280, radial ports 362 in the liner, an external annular groove 364 therein, and passages 366, 368 and 370'in the engine valve housing 278, the passage 370 communicating with the annular channelv 284 which, as hereinbefore. stated, always contains spent operating fluid atthe-exhaust pres.- sure. gineavalve 236. occurs at a reduced speed determined by the resistanceof the thread. 354.

Threadedinto the ends of the engine valve. housing 278. in alignment with the enginevalve 236 are adjustable. stops 372 and 374, the. former being engageable with the piston 334 and. the latter. being engageable with the lower endoflthe engine valve. As will be apparent, by screwing the stop 372 into the engine valve bore 282, the piston 334 ismoved downwardly to shorten the upward travel of the engine valve. Similarly, screwing the stop 374- into the engine valve bore 282 shortens the downward travel of. the enginevalve. With thestops 372 and 374 adjustedas. shown, the. engine valve is capable of its maximum travel.

As will be apparent, reducing the travel of the engine valve 236 by means of thestops 372 and 374 in the foregoing manner causes the engine valve to connect. the annular groove 298 to the annular grooves 288 and 304 through the ll-shaped throttling notches 324 at the ends of the annular channel 322. Thus, depending on.whether the engine valve 236 is in its upper position, or. its lower position, the notches 324 throttle the flow of operating fluid under pressure to the engine piston 84 and the charging pump115'6, or the flow of spent operating fluid from the engine piston and the charging pump. Thus, the upward and downward speeds of the reciprocable assembly of the pumping unit 56 can be reduced from the maximum values attainable when the adjustable stops 372 and 374 are retracted, the speed reductions attainable depending on the extent to which the stops 372 and 374 are screwed into the engine valve bore 282. Thus,

the speeds of the pumping unit 56 in the upward and downward directions may be controlled independently of each other. Similarly, the speeds of: the pumping unit 56 may be varied independently of the speeds of other pumping units in the system, such as the pumping unit 58, with the attendant advantages hereinbefore discussed;

Considering in more detail the fluid operated means for moving the pumping unit 56 vertically to properly position the pump piston 68 thereof in the pump cylinder 72, and referring to FIG; 1O of the drawings, the manually Thus, the final downward movement. of the en 15 operable valve 210 is disposed in a counterbore 376 in the head 60 and is provided with a head 378 threaded into a counterbore 389 so that rotation of the valve 210 moves it toward and away from a seat 382 formed at the junction of the counterbore 376 and a passage 384. Thisv passage communicates with the annular channel 242 which, as hereinbefore explained, is alternately connected to operating fluid pressure and exhaust pressure by the engine valve means 112. A diagonal port 386 connects.

the counterbore 376 to an annular channel 388 in the pumping unit head 60, this channel communicating with the downwardly facing area 286 of the pumping unit head. As will be apparent, opening of the valve 210 when the engine valve 236 is in its lower position results in the application of operating fluid pressure to the area 286 to lift the pumping unit 56. Conversely, opening.

204 and is threaded into the well head 36. A block 396.

having internal keys 398 adapted to fit into the grooves in the rod 390 is secured to the flange 394 by cap screws 400, or the like. Thus, with the block 396 in place, the pumping unit 56 is mechanically locked against vertical movement. This locking block is installed after the pumping unit 56 has been moved hydraulically, either upwardly or downwardly, into the position necessary to properly locate the pump piston 68 in the pump cylinder 72 under load.

It is thought that the operation of the various components of the pumping unit 56 will be apparent from.

the foregoing description and that a separate discussion.

of the operation thereof is unnecessary.

Although exemplary embodiments of the present invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims which follow.

I claim:

1. In a fluid operated pumping system for two or more wells, the combination of: a supply reservoir; a supply pump having its inlet connected to said supply reservoir for supplying operating fluid under pressure; fluid operated pumping units for pumping the wells, respectively, each of said pumping units including a reciprocable as: sembly comprising a pump piston within the corresponding well and an engine piston connected thereto, said engine piston of said reciprocable assembly of at least one of said pumping units being connected to said pump piston thereof by a rod string and being adjacent the surface, each of said pumping units including engine valve means adjacent said engine piston thereof for alternately connecting said engine piston to said supply reservoir and the outlet of said supply pump so as to reciprocate said reciprocable assembly of such pumping unit, and said one pumping unit including a counterbalance piston connected to said reciprocable assembly thereof; a counterbalance accumulator; means for connecting said counterbalance accumulator to said counterbalance piston of. said one pumping unit to counterbalance the weight of said rod string; a counterbalance reservoir; a compressor actuable by said one pumping unit in response to reciprospasms l7 ervoir into said counterbalance accumulator, said pumping means being connected in series with and being controlled by said engine valve means ofsaid one pumping unit.

2. In a fluid operated pumping system for two or more wells, the combination of: a supply reservoir; a supply pump having its inlet connected to said supply reservoir for supplying operating fluid under pressure; fluid operated pumping units for pumping the wells, respectively, each of said pumping units including a reciprocable assembly comprising a pump piston within the corresponding well, an engine piston adjacent the surface and a rod string interconnecting said engine and pump pistons, each of said pumping units including engine valve means adjacent said engine piston thereof for alternately connecting said engine piston to said supply reservoir and the outlet of said supply pump so as to reciprocate said reciprocable assembly of such pumping unit, and each of said pumping units including "a counterbalance piston connected to said reciprocable assembly thereof, each of said counterbalance pistons having a downwardly facing area; a counterbalance accumulator; means for connecting said counterbalance accumulator to said downwardly facing area of said counterbalance pistons of said pumping units to counterbalance the weights of said rod strings; a counterbalance reservoir; compressors actuable by said pumping units, respectively, in response to reciprocatory movement of said reciprocable assemblies thereof and communicating with said counterbalance reservoir for pressurizing said counterbalance reservoir; and a fluid operated pumping means actuable by one of said pumping units for pumping fluid from said counterbalance reservoir into said counterbalance accumulator, said pumping means being connected in series with and being controlled by said engine valve means of said one pumping unit.

3. In a fluid operated pumping system for two or more wells, the combination of: a supply reservoir; a supply pump having its inlet connected to said supply reservoir for supplying operating fluid under pressure; fluid operated pumping units for pumping the wells, respectively, each of said pumping units including a reciprocable assembly comprising a pump piston within the corresponding Well, an engine piston adjacent the surface and a rod string interconnecting said engine and pump pistons, each of said pumping units including engine valve means adjacent said engine piston thereof for alternately connectingsaid engine piston to said supply reservoir and the outlet of said supply pump so as to reciprocate said reciprocable assembly of such pumping unit, and each of said pumping units including a counterbalance piston connected to said reciprocable assembly thereof; a counterbalance accumulator; means for connecting said counterbalance accumulator to said counterbalance pistons of said pumping units to counterbalance the weights of said rodstrings; a counterbalancevreservoir; compressors actuable by said pumping units, respectively, in response to reciprocatory movement of said reciprocable assemblies thereof and communicating with said counterbalance reservoir for pressurizing said counterbalance reservoir, said compressors including said counterbalance pistons, respectively; and a fluid operated pumping means actuable by one of said pumping units for pumping fluid from said counterbalance reservoir into said counterbalance accumlator, said pumping means being connected in series with and being controlled by said engine valve means of said one pumping unit.

4. In a fluid operated pumping system for two or more wells, the combination of: a supply reservoir; a supply pump having its inlet connected to said supply reservoir for supplying operating fluid under pressure; fluid operated pumping units for pumping the wells, respectively, each of said pumping units including a reciprocable assembly comprising a pump piston within the corresponding well, an engine piston adjacent the surface and a rod string interconnecting said engine and pump pistons, each of said pumping units including engine valve means adjacent said engine piston thereof for alternately connecting said engine piston to said supply reservior and the outlet of said supply pump so as to reciprocate said reciprocable assembly of such pumping unit, and each of said pumping units including a counterbalance piston connected to said reciprocable assembly thereof; a counterbalance accumulator; means for connecting said counterbalance accumulator to said counterbalance pistons of said pumping units to counterbalance the weights of said rod strings; a counterbalance reservoir; compressors actuable by said pumping units, respectively, in response to reciprocatory movement of said reciprocable assemblies thereof and communicating with said counterbalance reservoir for pressurizing said counterbalance reservoir; a fluid operated pumping means actuable by one of said pumping units for pumping fluid from said counterbalance reservoir into said counterbalance accumulator, said pumping means being connected in series with and being controlled by said engine valve means of said one pumping unit; and fluid operated means connected to said pumping units, respectively, for moving said pumping units vertically in the Wells, respectively.

5. In a fluid operated pumping system for two or more well-s, the combination of: a supply reservoir; a supply pump having its inlet connected to said supply reservoir for supplying operating fluid under pressure; fluid operated pumping units for pumping the wells, respectively, each of said pumping units including a reciprocable assembly comprising a pump piston within the corresponding well, an engine piston adjacent the surface and a rod string interconnecting said engine and pump pistons, each of said pumping units including engine valve means adjacent said engine piston thereof for alternately connecting said engine piston to said supply reservoir and the outlet of said supply pump so as to reciprocate said reciprocable assembly of such pumping unit, and each of said pumping units including a counterbalance piston connected to said reciprocable assembly thereof; a counterbalance accumulator; means for connecting said counterbalance accumulator to said counterbalance pistons of said pumping units to counterbalance the weights of said rod strings; a counterbalance reservoir; compressors actuable by said pumping units, respectively, in response to reciprocatory movement of said reciprocable assemblies thereof and communicating with said counterbalance reservoir for pressurizing said counterbalance reservoir; a fluid operated pumping means actuable by one of said pumping units for pumping fluid from said counterbalance reservoir into said counterbalance accumulator, said pumping means being connected in series with and being controlled by said engine valve means of said one pumping unit; and fluid operated means connected to saidpumping units, respectively, for moving said pumping units vertically in the wells, respectively, saidjfluid operated means being connected in series with and con-' trolled by said engine valve means, respectively.

6. In a fluid operated pumping system, the combination of: a fluid operated pumping unit including a reciprocable assembly comprising interconnected engine and pump pistons and including engine valve means for alternately applying operating fluid pressure and exhaust pressure to an area of said engine piston so as to reciprocate said reciprocable assembly, said pumping unit further including a counterbalance piston connected to said reciprocable assembly, said counterbalance piston having a downwardly facing area; and counterbalancing means for applying a substantially constant counterbalance pressure to said downwardly facing area of said counterbalance piston so as to counterbalance the Weight of said reciprocable assembly, said counterbalancing means including a counterbalance reservoir and said counterbalance piston being reciprocable in a counterbalance cylinder having inlet and outlet valve means disposed above said counter 19 balance piston with said outlet valve means in communication with said counterbalance reservoir, whereby said counterbalance piston acts as a compressor piston to pressurize said counterbalance reservoir in response to reciprocatory movement of said reciprocable assembly.

7. A fluid operated pumping system as defined in claim '6 wherein said counterbalancing means includes a counterbalance accumulator connected to said downwardlyfaoing area of said counterbalance piston and includes fluid operated pumping means connected to said counterbalance reservoir and connected in series with and controlled by said engine valve means for pumping fluid from said counterbalance reservoir into said counterbalance accumulator.

8. A fluid operated pumping system including: a fluid operated pumping unit including a reciprocable assembly comprising interconnected engine and pump pistons and including engine valve means for alternately applying operating fluid pressure and exhaust pressure to an area of said engine piston so as to reciprocate said reciprocable assembly, said pumping unit further including a counterbalance piston connected to said reciprocable assembly, said counterbalance piston having a downwardly facing area; and counterbalancing means for applying a substantially constant counterbalance pressure to said downwardly facing area of said counterbalance piston so as to counterbalance the weight of said reciprocable assembly, said counterbalancing means including a counterbalance accumulator connected to said downwardly facing area of said counterbalance piston and including fluid operated pumping means in series with and controlled by said engine valve means for pumping fluid into said counterbalance accumulator.

9. In a fluid operated pumping system, the combina tion of: a fluid operated pumping unit including a reciprocable assembly and including engine valve means for alternately connecting an area of said reciprocable assembly to operating fluid pressure and exhaust pressure to produce reciprocatory movement of said reciprocable assembly; an accumulator; and fluid operated pumping means in series with and controlled by said engine valve means and in parallel with said fluid operated pumping unit for pumping fluid into said accumulator.

10. In a fluid operated pumping system, the combination of: a fluid operated pumping unit including a reciprocable assembly and including engine valve means for alternately connecting an area of said reciprocable assembly to operating fluid pressure and exhaust pressure so as to reciprocate said reciprocable assembly; and a compressor actuable by said pumping unit and including a compressor cylinder having therein a compressor piston axially aligned with and connected to said reciprocable assembly, said compressor including inlet and outlet check valve means communicating with said compressor cylinder.

11. A fluid operated pumping system as recited in claim including: a reservoir connected to said outlet check valve means of said compressor; an accumulator connected to said reservoir; and fluid operated pumping means connected in series and controlled by said engine valve means and in parallel with said fluid operated pumping unit for pumping fluid from said reservoir into said accumulator.

12. In a fluid operated pumping system, the combination of: a fluid operated pumping unit including a stationary assembly, including a reciprocable assembly reciprocable relative to said stationary assembly and comprising interconnected engine and pump pistons, and including engine valve means for alternatively connecting an area of said engine piston to operating fluid pressure and exhaust pressure to reciprocate said reciprocable assembly; and fluid operated means for moving said pumping unit vertically, said fluid operated means being connected in series with said engine valve means and controlled thereby.

13. A fluid operated pumping system in aGQQIQQHce with claim 12 wherein said engine valve means includes an engine valve reciprocable between two positions and having means for connecting saidarea of said engine piston and said fluid operated means to operating fluid pressure in one of the positions thereof and for connecting said area of said engine piston and said fluid operated means to exhaust pressure in the other position thereof.

14. In a fluid operated pumping system for two or more wells, the combination of: fluid operated pumping units for pumping the wells, respectively, and each including a reciprocable assembly comprising interconnected engine and pump pistons, engine valve means for alternately connecting said engine piston thereof to operating fluid pressure and exhaust pressure, and means connected to said reciprocable assembly thereof for hydraulically counterbalancing said reciprocable assembly; and means for applying counterbalance fluid pressure to said counterbalancing means of said pumping units, including fluid operated pumping means connected in series with and controlled by said engine valve means of one of said pumping units.

15. In a fluid operated pumping system for two or more wells, the combination of: a supply reservoir; a supply pump having its inlet connected to said supply reservoir for supplying operating fluid under pressure; fluid operated pumping units for pumping the wells, respectively, each of said pumping units including a reciprocable assembly comprising a pump piston within the corresponding well and an engine piston connected thereto, said engine piston of said reciprocable assembly of at least one of said pumping units being connected to said pump piston thereof by a rod string and being adjacent the surface, each of said pumping units including engine valve means adjacent said engine piston thereof for alternately connecting said engine piston to said supply reservoir and the outlet of said supply pump so as to reciprocate said reciprocable assembly of such pumping unit, and said one pumping unit including a counterbalance piston connected to said reciprocable assembly thereof; and means for applying counterbalance pressure to said counterbalance piston of said one pumping unit to counterbalance said weight of said rod string, including pumping means for producing said counterbalance pressure, including means for actuating said pumping means, and including means interconnecting said one pumping unit and said actuating means for controlling said actuating means.

16. In a well pumping system, the combination of: a well head; a pump cylinder suspended from said well head; an engine cylinder movable vertically relative to said well head; a pump piston reciprocable in said pump cylinder; an engine piston reciprocable in said engine cylinder; a rod string interconnecting said engine and pump pistons; and fluid operated means for moving said engine cylinder vertically relative to said well head to match the stroke of said pump piston relative to said pump cylinder to the stroke of said engine piston relative to said engine cylinder, said fluid operated means providing a downwardly facing area connected to said engine cylinder and including means for applying fluid pressure to said area.

17. In a well pumping system, the combination of: a well head; a pump cylinder suspended from said well head; an engine cylinder movable vertically relative to said well head; a pump piston reciprocable in said pump cylinder; an engine piston reciprocable in said engine cylinder; a rod string interconnecting said engine rand pump pistons; means for moving said engine cylinder vertically relative to said well head to match the stroke of said pump piston relative to said pump cylinder-to the stroke of said engine piston relative to said engine cylinder; and means for locking said engine cylinder against vertical movement relative to said well head.

(References on following page) UNITED STATES PATENTS Petsche Sept. 12, 1899 Steiner June 16, 1903 Stewart Oct. 7, 1919 Hubbard Mar, 1, 1927 Granger Feb. 24, 1931 Hobson May 2, 1933 22 V Clapp May 16, 1933 Many July 31, 1934 Kennedy Jan.- 1, 1935 Purdum Mar. 26, 1935 Scheider Sept. 5, 1939 Farley et a1. Jan. 9, 1945 Smith Aug. 14, 1951 Smith Sept. 30, 1952 Salentine Aug. 20, 1957 UNITED STATES PATENT OFFICE CERTIFICATE oF CORRECTION Patent No. 3 OO5 4l3- October 24V 1961 Q I Clarence J (igoberly Q It is hereby certified that error appears in the above numbered patent requiring correction andcth'at the said Letters Patent should read as corrected below.

Column 8 line 73 for "consequent" read subsequent column 14 line 52 strike out "25"; column l5 line 1 for "parts" read ports column 19 line 59 after "series" insert with line 68 for "alternatively" read alternately Signed and sealed this 10th day of April 1962a (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting ff Commissioner of Patents

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