US2348004A - Oil well pumping unit - Google Patents

Description

May 2, 1944. F. A. GRUETJEN 011. WELL PMPING UNIT Filed April 28, 1941 1NVENTOR."; v

Frederztk Afuejen f KLM ATTozNEx Patented May 2, 1944 OIL WELL PUMPING UNIT Frederick A. Gruetjen. Milwaukee, Wis., assignmto A. 0. Smith Corporation, Milwaukee, Wis., a corporation of New York Application April 28, 1941, Serial No. 390,781

(Cl. S-45) 13 Claims.

This invention relates to an improvement in pumping units to pump oil or other liquids from deep wells.

Reciprocating plunger pumps driven by sucker rods have long been used for the pumping of oil from deep wells. Increasing depth of wells has led to increasing diiiiculties connected with the long string of sucker rods running from the pump tothe surface of the earth and has spurred the development of self-contained pumping units placed at or near the bottom of the well and driven by electricenergy conveyed to the unit through an electric cable. In one type of these pumping units, an electric motor is used to drive a power pum-p which circulates carefully cleanedand purified power oil from a reservoir through the power pump, a distributing valve, and a long stroke, slow speed, reciprocating hydraulic motor and back to `the reservoir. 'Ihe hydraulic motor is direct connected to a plunger pump of the same general type that has been operated by sucker rods. This invention `relates lto an improvement in pumping units of this general kind, and more specifically, to means for returning to the power oil reservoir any power oil which leaks past the packing on the piston rod of the hydraulic motor.

An object of the invention is to provide means to prevent loss of power oil from its circulation system by leakage at the hydraulic motor.

Another object of the invention is to provide means to prevent entry of crude oil from the well into the power oil circulating system.

These andother objects of the invention will be clear from the following detailed descriptiony valve in the partition between the motor com...`

pertinent and the oil reservoir;

Fig. 3 shows a pump which maybe employed in removing either the crude oil or pumping fluid which has leaked PU'S the packing; .and

Fig. 4 is an alternative means for-returning leakage power oil toits reservoir.

'Ihe various parts of the pumping -unit are assembled in a casing l which may have certain detailed features of construction that are Drovided to facilitate assembly but are-not shown in the drawing as they form-'no .part of this invention.

The motor tysupplied with electric energythroughcablelextendingtromthepump"-v lng unit t0 the surface of drives the power pump d by means of shaft 5. An oil reservoir 6, separated from the motor compartment by a partition 7, serves for storage of the power oil.

A distributing valve 8 controls the iiow of power oil to and from the cylinder 9 of the hydraulic motor. The cylinder contains a piston lo on a piston rod il which extends downward into the pump barrel I2 of the crude oil pump and forces oil from the Well to the surface. Four sets of packing rings, I3, i4, i5 and I6 are provided around the piston rod for purposes hereinafter set forth in detail.

In the operation of a pumping unit of this kind, thev electric motor 2 drives powerpump 4 which may be of any suitable type adapted for connection to the motor, either directly or through reducing gears. The pump 4 draws power oil from reservoir 6 and forces it through distributing valve 8 and from there alternately to the opposite ends of the cylinder 9 ol' the hydraulic motor. The distributing valve is of such a nature as to admit oil from the pump to one end of cylinder 9, simultaneously exhaust oil from the other end of the cylinder back to reservoir 6, and reverse the flow of oil when the piston l0 reaches each end oi its stroke, thus causing the piston with its attached plunger to reciprocate back and forth in the cylinder of the hydraulic motor. The valve may be operated either mechanically or hydraulically. The details of its construction and of the oil connection between the reservoir. power pump, valve,

and cylinder are not shown as they form nopart of this invention. l

The crude oil pump in the'pump -barrel I2 may be either single or. 'double acting and in either case is operated by the piston rod Il. 'The speciiic construction of the pump is likeand is,

well into the power oil circulating system where .a

sand and grit from the well would damage the power pump and interfere with the operation 'of the distributing valve.

Due to the hydrostatic headin deep wells, high oil pressures are necessarily involved in both the crude oil pump and in the'hydraulic motor. `It is apparent, therefore, that great care is needed tonieet the requirements outlined above.

To this end.'san'd scrapers Hare providedV around the piston rod I I. These operate to scrape olf sand and grit as the plunger moves upward from its immersion in the crude oil in the pump barrel, and keep the packings free from grit. Two packings I3 and I4 are provided to prevent the leakage of oil upward along -the plunger. Similarly, packings I5 and I6 serve to prevent leakage of power oil downwardlyv from cylinder 9. The crude oil pressure below packing I3 is considerable, being due to thesum of the hydrostatic, friction, and inertia heads of the column of fluid extending upward from the oil level in the well to the surface of the ground, or to the next uppermost pumping unit if two or more are used in series. Because of the high pressure involved, it is dirhcult to provide any packing which will assure, for an extended period of operation, against all upward leakage of crude oil and the consequent lpossibility of its admixture with the power oil.

In order to provide this assurance, Aa vent I8 in the casing I is provided between packings I3 and I4. The vent is arranged to open into the well from which the oil is pumped, 'and to return to it any crude oil which may leak upward past packing I3. As the immersion of the pumping unit in the well is far less than the height to which the oil is pumped, the pressure acting below packing I4 is relatively small and the packing can be relied upon to prevent upward leakage of crude oil past it. These means provide for preventing admixture of crude oil with the power oil and consequent possibility of damage to the mechanism. Packingv I4 which is above the vent I8 serves to prevent crude oil from passing further upwardly "falong the piston under the pressures of submerpiston rod II. This is less than the volume withdrawn, and consequently, when the piston moves down, the oil level 25 in the reservoir 6 also moves down. Conversely, when the piston moves up, the oil level in the reservoir also moves up.

Downward movement of the oil level 25 when the piston moves down expands the vgas in the upper part of reservoir 6 and lowers its'pressure.

' Check valve 22 is held closed since the pressure below it is greater than the pressure above, but the check valve 23 opens to permit the passage of oil K and gas from the motor compartment into reservoir 6. There is, therefore, also a reduction of the gas pressure in the motor compartment and oil from sump I9 rises in the tube or passageway 2| to a level which corresponds to the difference between the gas pressures in the sump and motor compartment.

When the piston I0 reverses its stroke and begins to rise, the oil level 25 in reservoir 6 rises with it, compresses the gas in the upper part of the reservoir,l and closes check valve 23 in the partition between the reservoir and motor compartment to prevent a corresponding increase of gas pressure inthe motor compartment. The increased gas pressure in the oil reservoir is transmitted through Atube 20 and its valve 22 to the sump I9 and forces oil from the sump upward through tube 2I into the motor compartment in which the gas pressure has a lower value due to the operation of check valve 23. On the next downward stroke of the piston, check valve 23 opens as previously described due to lowering of the oil level in the reservoir and consequent reduction in gas pressure, and the oil previously the piston rod II passes out of the hydraulic motor through packings l I5 and I6. Any of the power oil which may leak downward past the` packing I5, collects in the space between packings I5 and I6 and drains into the closed sump I9.

` From here it is pumped back tothe oil reservoir.

This is accomplished by connecting a tube or passageway 20 to the upper part of oil reservoir 6, and a tube or passageway 2| to the motor compartment. The first of these tubes or passageways 20 opens into the upper part of the sump; the other, 2|, into the lower part.' A check valve v 22 is provided in tube 20, and another check valve 23 in a passage 2 4, in the partition 1 between the oil reservoir 6 and the motor compartment. The first of these valves 22, opens when the pressure in thereservoir 6 exceeds that in the lower part of tube 20; the second valve, 23, opens when the pressure in the motor compartment exceeds,the pressure in the oil reservoir.

Assume now, that a small amount of "power, oil has accumulated in su'mp I9 due to leakage past packing I5 and that the pistoni 0 of the hydraulic forced up from the sump to the motor compartment is returned to the oil reservoir. As a consequence of the periodic motion of the piston. any leakage of power oil past packing I5 is returned to the reservoir and not lost. In case there is no oil leakage, there is merely a circulation of gas through the sump.

While in the embodiment illustrated in the drawings, a tight partition 1s provided between the oil reservoir and the motor compartment and the oil from the sump is returned to the latter, it.

is possible to dispense with partition 1 and return the oil from the sump to some other 88.8 space located above the oil reservoir and sept arated from it by a check valve. For the purpose of more clearly1 illustrating the invention, the oil sump I9 and tubes 20 and 2I are shown to one y'side of the casing I which encloses the pumping unit. It is to be understood, of course, that in an actual construction, these parts will also be within the casing. l

Referring now to Fig. 3, which illustrates a pump that can be employed for pumping the crude oil which has leaked past packing I3, the packings I3 and I4 are spaced apart a distance greater than the length of stroke of the piston rod II, and the latter is provided with a depression 26 located at a point which never comes into contact with either packing. A smally piston pump 21 has its plunger 28 connected to' pivoted spring pressed arm 29 on which a roller 30 is journaled `to ride against; piston rod II and to enter and leave the depression 26 to reciprocate plunger 28' as the rod I I moves up and down.

The pump 21 has its intake connected to vent I8 and its discharge to the outside of the casing. rvThe intake and discharge ports have suitable check valves. The pump serves to keep a s ucclaims.

of crude oil leaking upwardly into the power iluid system.

A similar pump may be provided between packings I5 and I6 for the power uid. In this case, the pump intake would be connected to sump 9 and the pump would discharge into reservoir Fig. 4 illustrates a modified form of pump for returning leakage fluid, in this case from the space between packings ISand I6 to the power iiuid reservoir. This pump comprises a plunger 3| extending .through the sump chamber 32 and into a cylinder 33. The plunger 3| is reciprocated by a motor piston 34 in a cylinder 35 at the upper end of the plunger rod. The upper end of cylinder 35 is connected Iby a passage to the upper end of the power cylinder 9 and thelower end of cylinder 35 is similarly connected by a passage to the lowerend of the power cylinder 9 to effect operation of the plunger 3| in synchronism with the piston I and rod il.

'I'he cylinder 33 has its intake directly from chamber 32 when the plunger 3l is raised and its outlet is through check valve 36 and passage 31 leading from the bottom end of the cylinder 33 to 25 the reservoir 6. The' check valve 3B prevents return of oil from thereservoir to'cylinder 33 upon upward movement of the plunger 3l and allows the cylinder to fill from chamber 32 when the plunger uncovers the upper end of the cylinder.

The detail construction of the packings illustrated herein is set forth and claimed in the co.

pending application Serial Number 390,783 filed on even -date herewith by the present inventor ,now Patent 2,320,589, June 1, 1943. Certain features of the present invention constitute an improvement upon the invention set forth and claimed, in applicants co-pending application Serial Numberv 390,782 filed on even date herewith now Patent 2,330,419, Sept. 28, 1943.

Various embodiments ofthe invention may be employed within the scope of the accompanying I claim: l. In a deep lwell pumping unit having a reciprocating hydraulic motor, a liquid reservoir for the storage4 of power oil with a liquid level which periodically rises and falls during the operation of the unit, a closed gas space above the liquid'level inothe reservoir in which gas is alternately increased and decreased in pressure by the rising and falling of the liquid level, a second closed gas space separated from the rst by a check valve which opens when the gas pressure is greater in the second than in the rst and closes when the pressure difference is reversed, a packing around the piston rod of the hydraulic -motor to prevent leakage of power uid from the hydraulic motor, a sump below the packing to collect any liquid which may leak past the packing, a

passageway joining the ilrst gas space to the upper A portion of the sump, a check valve in the passage- Way to permit the ilow of gas to the sump but not` away from it, and a uid passageway to return liquid collected in the sump to the second named gas space.

2. In' a deep well pumping unit, a reciprocating hydraulic motor driven by power liquid under pressure, packing around the piston rod to prevent `the leakage of power liquid from the cylinder of the hydraulic motor, a sump below the lpacking to collectl any liquid which may leak past the packing, and pneumatically operated means `to restore fluid from .the sump to the power liquid system. l

3. In a deep well pumping unit, a vertically disposed cylinder of a reciprocating hydraulic motor, a pump barrel below the cylinder, a piston rod extending from the piston of the hydraulic motor into the pump barrel, four packings around the piston rod of which two are disposed to prevent leakage from the pump barrel upwards longitudinally of the piston rod and the other two to prevent leakage of power liquid from the hyl0 draulic motor, a vent between the rst two packings opening into the supply of -uid to rbe pumped, a sump between the other two packings to collect power liquid which may escape past the packing from the hydraulic motor, and pneumatically operated means to return liquid from the sump I to the power liquid circulating systems.

4. In a pumping unit having a pump with a pump casing, a reciprocating hydraulic motor with a.piston rod which extends from the motor '20 cylinder into the pump, packing between the rod and pump casing, means to collect any liquid which may leak past the packing and return it to the source from which it is pumped, packingbetween the rod and cylinder of the hydraulic motor, means to collect power liquid which may leak past the second named packing, and pneumatically operated means to return the liquid so collected to the power liquid circulating system.

5. In combination with a reciprocating hydraulic motor, a Aliquid storage reservoir from which liquid is pumped to operate the motor and in which the lquii level rises and falls as the motor operates, a closed gas space above the liquid level in the reservoir in which gas is alternately compressed and expanded by the rise and fall'of the liquid leve1,.a second closed gas space, a check valve between the two which -opens when the pressure in the second exceeds that in the rst and closes when the pressure difference is reversed, packing between thecylinder and piston rod of the hydraulic motor, a sump to collect any liquid which may: leak past the packing, a passageway from the iirst gas space to the sump, a check valve in the fluid passageway ,to permit ilow of gas to the sump but not in the reverse direction, and a second iluid passageway to return liquid from the' sump to the second named gas space and having its opening beneath the liquid level in the sump.l

6. In combination with a reciprocating hydraulic motor having a piston rod, a liquid storage reservoir from which liquid is pumped to operate the motor and in which the liquid level rises and falls as the motor piston reciprocates, a closedy panded by the rise and fan of the nquid level, a.

second closed gas space in communication with said first gas space, apacking around the piston rod of the hydraulic motor in the wall oi the motor cylinder to prevent escape of power liquid past the piston rod, a sump to collect any 'liquid which may leak past .the packing, passages connecting the sump to each of the gas spaces, means restricting the flow between the two gas spaces in the communication referred to to one direction,

land means restricting the ilowthrough the passages from one gas space through the sump to the f other gasv space to a direction opposite to said rst named ilow, the opening for the outlet pasblow the liquid level in lect any liquid which may leak past the packing, and means responsive to the operation of said motor to restore fluid from the sump to the power liquid circulating system. i

8. In a deep well pumping unit having a reciprocating hydraulic motor with a piston rod, means for preventing loss of power fluid for driving said motor,- comprising a series of packings surrounding said piston rod and disposed to prevent the leakage of power fluid along the rod from said motor, a take-oit for power fluid which may leak past the set of packing nearest the motor, and means operated by said motor to return the 'power fluid from said take-of! to the main body of power iiuid.A

9. In a deep well pumping unit having a reciprocating hydraulic motor with a piston rod,

ciprocating pump driven by ya reciprocating hydraulic motor by means of a piston rod common to both, means for preventing loss of power fluid for driving said motor and of admixture of crude oil with the power uid, comprising a series of packings surrounding said piston rod and disposed to prevent the leakage of crude oil along the rod from said pump and the leakage of power fluid along the rod from said motor, 'a take-off for crude oil which may leak past the set of packving nearest the pump, a. similar take-off for power fluid which may leak past the set of packing near- -said motor, a take-off for power fluid which may leak past the set of packing nearest the motor, and a pump operated in synchronism with the movement of the piston rod for returning uidA from the take-off to the main body of power iiuid.

10. In a deep well pumping unit having a reciprocating pumpdriven by a reciprocating motor by means of a piston rod, means for preventing r iiuid being pumped from leaking along the piston rod to the motor, comprising a series of packings surrounding said piston rod anddisposed to prevent the leakage of fluid therealong from the surrounding said piston rod and disposed to prevent the leakage of power fluid along the rod from said motor, a take-'off for power fluid which may leak past the set of packing nearest the motor, and a scavenger pump operated by the power uid driving said motor for returning said leakage fluid from the take-off to the main body of power iiuid.

13. In combination with 'a reciprocating rod, a pair of circumferential packing members engaging said rod and spaced apart a distance at least as great as the reciprocating stroke of the rod to prevent any liquid on the surface of the rod passing through both packngs during reciprocation of the rod, a pump disposed between the packing members for withdrawing any leakage fluid from therebetween, andmeans on said rod for engaging the operating member of said pump for operating the latter when the rod is reciprocated.

FREDERICK' A. GRUETJEN.

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