US2778313A - Control means for pumping apparatus - Google Patents

Description

Jan. 22, 1957 R. H. HILL 2,778,313

CONTROL MEANS FOR PUMPING APPARATUS Filed Dec. 17, 1951 J6 J7 J6 o o o c jg MHGSt Z VC CH 26 O O O o R 7 4m? Tit-IE MOST}? Q INVENTOR.

United States Patent 9 CONTRDL MEAN 3 FOR PUMPING APPARATUS Robert H. Hill, Fort Wayne, lnd., assignor, by mesne assignments, to Perfect Circle Corporation, lingerstown, 1:18., a corporation of Indiana Application December 17, 1951, Serial No. 262,156

6 Claims. (Cl. 1ll325) This invention relates generally to pumping apparatus for oil wells or the like and more particularly to a novel control means for such apparatus.

It is a frequent occurrence in oil wells, particularly in oil wells of the low pressure type where it is necessary to remove the oil by pumping the same out of the well through suitable tubing, that the sand strata or other producing formations at the bottom of the well eventually become clogged or obstructed to such an extent that the yield from the well becomes too low to warrant further operation of the well. In some cases the well is abandoned, but in many instances an attempt is made to clean the well by forcing water, acid, or other suitable purging material into the producing formation whereby to remove the obstructions in the formation and restore the flow of oil to a profitable level. In some cases the purging fluid may even contain added solid material for the purpose of further expanding and enlarging the producing formation. Heretofore, in cleaning an oil Well it has been necessary to remove the production tubing from the well together with the usual reciprocating pump and sucker rod in order to permit the insertion of a temporary pipe into the well casing for injecting the cleaning fluid into the well. Upon completion of the cleaning operation, the temporary pipe had to be removed and the reciprocating pump with its sucker rod and tubing reinstalled before the production of oil could be resumed. Obviously, this manner of cleaning an oil well is cumbersome and time consuming and involves substantial expense. In fact, in many cases where the production of the well at best is small, it is questionable whether the expense of cleaning the well is warranted.

However, it has been found that by means of a novel reversible pumping arrangement it is possible to effect alternate or intermittent periods of production and pressurizing or purging of the well in a very convenient and reliable manner and at relatively low cost. In general, this apparatus comprises the combination of a reversible rotary pump and a reversible electric motor connected closely adjacent the pump so that the entire apparatus may be positioned adjacent the bottom of the well. When the production of the well diminishes to an undesirably low level, the operation of the apparatus can be reversed to pump oil or other suitable purging fluid downwardly and under pressure through the production tubing into the well whereby to purge or otherwise remove obstructions from the production strata and the fluid intake of the apparatus. A suitable packer is provided in the well casing for confining the fluid pressure to the lower portion of the well during the pressurizing periods. Reference is made to my copending applications 5. N. 227,845, filed May 23, 1951, issued as Patent Number 2,737,119 on March 6, 1956, and S. N. 247,227, filed September 19, 1951, issued as Patent Number 2,739,650 on March 27, 1956, for various details of the pumping apparatus.

The present invention is particularly concerned with a novel control means for preventing overheating of the reversible pump section of the apparatus. As will hereice inafter appear, the preferred type of reversible pump for use in a pumping apparatus of the character described requires the presence of a liquid phase within the pump in order to insure adequate lubrication of the pump elements. Utherwise, the pump Will overheat with the danger of serious damage to the operating parts.

Accordingly, a primary object of the invention is to provide novel control means for a reversible pumping apparatus for use in oil wells and the like.

Another object of the invention is to provide novel means for preventing overheating of the pump section of a reversible pumping apparatus for use in oil wells and the like.

A further object of the invention is to provide a novel combination of a reversible pumping apparatus and temperature responsive control means for permitting operatron of the pump only below a predetermined maximum temperature.

Other objects and advantages of the invention will become apparent from the subsequent detailed description taken in conjunction with the accompanying drawing which is a diagrammatic representation of the essential elements of an electrical circuit for a reversible pumping apparatus and a temperature responsive control means embodying the features of my invention.

As hereinbei'ore mentioned, the pumping apparatus to which the present invention pertains is adapted to be positioned adjacent the bottom of an oil well casing, and in its preferred form the apparatus comprises a reversible motor section and a reversible pump section connected in end-to-end relation for fluid flow therebetween. A suitable fiuid intake or inlet is provided at the bottom of the apparatus, and an outlet pipe extends upwardly from the top of the apparatus through the well casing to the ground level.

During production, the reversible motor is operated so that the reversible pump draws oil from the bottom of the well casing through the inlet and discharges the oil through the outlet pipe which is connected to a tank or other storage facilities at the ground level. When the producing formation and/or the intake become clogged or obstructed to an objectionable degree, the motor is reversed and the pump is thereby operated in reverse fashion so that oil or other suitable purging material is pumped downwardly through the outlet pipe and is discharged from the intake under pressure. In order to insure that the oil or other purging material is forcibly injected into the adjacent producing formation at the bottom of the well, a portion of the pumping apparatus is fitted with a packer of a type adapted to resist upward pressure when in tight engagement with the inside of the well casing. As a result, the packer eilectively segregates the lower portion of the well so as to define a reservoir space between the packer and the bottom of the well. Thus, when oil or other purging material is pumped downward-1y into the well under pressure, the reservoir space is sealed at its upper end by the packer and the oil is therefore readily forced under high pressure into the obstructed producing formation or strata for purging and cleaning the same. At the same time, the intake or inlet at the bottom of the pumping apparatus is also cleaned and flushed out.

As described in. detail in my copending related applications identified above, the preferred type of pump comprises a reversible pump of the positive displacement type in which there is an elongated rotary pumping member having driving connections with the motor of the device for operation in either a clockwise or counterclockwise direction. More particularly, the invention contemplates the use of the progressing cavity type pump known commercially as the Moyno pump and comprising an elonarrears gated female helical member which constitutes the stator of the pump and an elongated male helical member mounted in the female member and constituting the rotor of the pump. The outer member or stator is provided with one helical thread more than the inner member or rotor, and thetwo members are so arranged and shaped that every thread of the rotor is constantly in contact with the stator in any transverse section through the pump. This relation of the rotor and stator is such that a plurality of closed spaces or cavities are defined between the two members because of the difference in the number of threads on each member. When the r tor is rotated relative to the stator, the cavities or spaces between the members are displaced in a longitudinal direction with the result that a fluid material can be axially transported between the two members to obtain the desired pumping effect. Reference is made to U. S. Patents Nos. 1,892,217 and 2,028,467 for a detailed consideration of the theory and operation of the progressing cavity type of pump. A reversible pump of the progrea sing cavity type is particularly desirable because it is capable of generating veryhigh pressures and because sand or other solids in the fluid being pumped do not cause undue wear or operating diti'iculties in a pump of this type.

Referring now to the drawing, a pump of the foregoing type is illustrated fragmentarily and comprises a tubular conduit ltl constituting the outer portion of the pump stator. The interior of the tube in is provided with a helical lining ll, preferably of synthetic rubber, which constitutes the female helical member hereinbefore referred to. An elongated male helical member or rotor 12 is operatively disposed within the helical liner lift of the pump stator for rotation in either direction. it will be understood that the upper end of the rotor 12 has suitable driving connections with the reversible electric motor of the apparatus, indicated diagrammatically at 13.

The control means which constitutes the primary feature of my invention comprises broadly a means for stopping the operation of the pump when the flow of oil or other liquid through the pump reaches an undesirably low rate or ceases entirely so that the pump tends to overheat. More specificaly, the control system in its preferred form operates on a temperature responsive principle. this end the control system includes a temperature responsive element attached to the pump, a switch mechanism in the motor circuit for starting and stopping the motor, and actuating means connected to the switch mechanism and to the temperature responsive element for opening and closing the switch mechanism in response to predetermined variations in the temperature of the pump. As will appear hereinafter, there are a number of diifercnt conditions which can arise in an oil well during both the production and pressurizing periods which require the provision of a control system of the present type in order to avoid overheating of the pump.

In the embodiment of the invention illustrated in the drawing,'the temperature responsive device comprises a thermostat M attached to the outside of the conduit re. The line terminals or conductors for supplying electric current to the motor 13 are designated at id, 17, and 18, the motor in this instance being of the three-phase type. These terminals are connected to a suitable magnetic switch of a conventional type illustrated diagrammatically'at 19. The switch 19 is in turn connected to the mtor 13 by means of suitable leads or conductors 21, 22, and 23. it will be understood that the magnetic switch 19 includes three pairs of spaced contacts together with magnetically actuated means for establishing and disrupt-- ing an electrical connection between each set of contacts. The structural details of the thermostat M and the magnetic switch 19 will be familiar to those skilled in the art and therefore need not be described in any greater detail.

Energization of the magnetic switch 19 for closing the electrical circuit to .the motor .113 .is accomplished by means of a separate electrical circuit which may utilize the same or different source of electrical current as the motor 13. in many cases, the motor 13, the switch 19, the thermostat lid may be selected to operate from a common source of electric current at a given voltage. However, by the use of a suitable transformer the motor and switch can operate on a current supply of higher voltage while the energizing circuit operates on a lower voltage. in this instance, the energizing circuit includes a step-down transformer 24 having its high voltage or input side connected by suitable leads 26 and 27 to the line terminals l7 and 1%, respectively, which may provide a voltage of 440 volts. The low voltage or output side of the transformer 24, which may provide a voltage of volts, is connected by a lead 28 to the energizing means (not shown) of the magnetic switch 19. As will be well understood, such energizing means may conveniently comprise an electromagnetic device having one or more energizing coils which, upon the passage of current therethrough, cause suitable switch closure members to bridge the gaps between the sets of switch contacts. The low voltage side of the transformer 24 is also connected by a lead 29 to the lead 23 of the motor circuit. The circuit through the energizing means of the switch 19 is completed by a lead Ell. extending to a single-pole singlethrow switch 32, a lead 33 connecting the switch 32 with the thermostat l4, and a lead 34 connecting the thermostat iui with the lead 23 of the motor circuit. it will be recognized that in the switch energizing circuit a single connection could be utilized between the output side of the transformer 24 and the thermostat l t in place of the loads 29 and 34 which are interconnected through the conductor 23. However, since the transformer 24 and the switch l? are normally located at the ground level While the thermostat M is secured to the pump adjacent the bottom of the well, it will readily be seen that the use of the conductor 23 in the manner illustrated eliminates the need for extending an additional wire to the bottom of the well in order to complete the switch energizing circuit.

The operatic-n of the device as described above is as follows. The manually operable switch 32 constitutes the master control switfh for starting and stopping the pumping apparatus. When the switch 32 is closed, the circuit through the energizing means of the magnetic switch 1% is thus completed whereupon the operating mechanism of the switch 1% is shifted to close the three sets of spaced contacts in the motor circuit. Thus, current is supplied directly from the line terminals 137-13 through the switch 19 and the leads 21-22-23 to the motor 13 for operating the pump rotor 12 in the desired direction of rotation. If for any reason the pump should overheat during operation, as hereafter explained, the excessive temperature will be detected by the temperature responsive element or thermostat Ed with the result that the switch energizing circuit is'disrupted and consequently the energizing means or the magnetic switch 1% is deenergized. Upon deenergization of the switch 19, it will be understood that the switch mechanism is automatically biased to open position so that the motor circuit is interrupted and the operation of the pump is stopped. In other words, the thermostat 14 operates to stop the motor and pump in the same manner as can be accomplished by operation of the hand switch 3 2. When the pump cools down sufficiently, the thermostat ll l automatically closes to reestablish the energizing circuit of the magnetic switch whereby to restore the apparatus to normal operation.

Dependent upon the temperature conditions prevailing in a particular well, the thermostat 14 is regulated to open and close the switch energizing circuit at predetermined maximum and minimum pump temperatures. For example, where the well temperature is on the order of 118 F., the thermostat 14 may be set to open at a temperature of 150 F. and to close at 125 F. When the prevailing well temperature is higher or lower, it will be understood that the thermostat setting will be changed I accordingly.

The nature of the progressing cavity type pump herein illustrated is such that it is necessary to have a liquid phase present at all times during operation of the pump to insure adequate lubrication between the rotor and the rubber-lined stator. In the event that the pump is operated for any appreciable length of time without such liquid lubrication, the resultant frictional Contact between the rotor 12 and the rubber liner 11 is such that the liner 11 heats up rapidly. if this condition is allowed to continue for too long a period, the rubber liner will ultimately be softened and in extreme cases will adhere or stick to the rotor 12 so that the pump binds and is seriously damaged. The control system of my invention in effect provides a continuous detection of the external temperature of the stator tube It) and thereby prevents any danger of overheating. As soon as the pump exceeds the upper limit of the thermostat the switch 19 thereby stopping the operation of the device until such time as the pump stator cools down to the lower operating setting of the thermostat.

There are a number of conditions which may be encountered in practice which may cause overheating of the pump mechanism. One common cause of overheating occurs during a production period and usually near the end thereof. It will beunderstood that during a production period the obstruction or clogging of the earth formations and the intake to the pumping apparatus is usually a gradual phenomenon until eventually a point is reached at which the oil flow is quite low and in extreme cases may cease entirely. Under such conditions of diminished liquid flow the normal pump lubrication is impaired and the pump heats upduring operation. In the event that substantially no liquid is being pumpe from the well, the pump heats up very rapidly. With the control means described above, it will be seen that when such conditions arise during production, the pump is automatically shut down thereby protecting the pump and at the same time providing a positive indication to the operator that pressurizing of the well is required. Thus, the control system is also effective as an indication of the operating requirements of the well Without the necessity of the operator maintaining a continuous visual check on the flow of oil from the well.

Another frequent cause of overheating occurs at the beginning of a production period and usually immediately following a period of reverse operation or pressurizing of the oil well. It has been found that upon the completion of such a pressurizing period, there is often a substantial accumulation of high pressure gas in the well such that the liquid oil is effectively driven back and retained under pressure in the producing formations of the well until this gas pressure is released. Thus, it will be seen that when production is resumed following a pressurizing period, the pump will of necessity operate almost exclusively on a gas phase until all of the accumulated high-pressure gas has been removed or released and a liquid oil phase is permitted to reach the inlet of the pump. in my copending application Serial No. 247,227, I have described and claimed a specific means for rapidly releasing this accumulation of highpressure gas with the object of minimizing the period of time during which the pump is operated without the necessary lubricating liquid. However, even with such rapid gas releasing means, it is highly desirable, as a safety factor, to employ the temperature responsive control circuit hereinbefore described so that even in this relatively brief interval of non-liquid or dry operation, the rubber lining of the pump stator will be adequately protected.

Although the frequent accumulation of high-pressure gas at the completion of a pressurizing period necessitates the protective features of my invention at the beginning of almost every production period, the control means is also quite important in connection with the pressurizing periods per se. During the pressurizing of the oil well, relatively large volumes of oil or other fluid may be pumped into the Well over an extended period without any appreciable reaction or change in well conditions. However, at some point during the pressurizing operation, the producing formation is sufficiently purged or disrupted so that a large volume of high-pressure gas frequently makes a very sudden appearance in the well. In some instances, the pressure of this newly released gas is so great that the back pressure of the gas interferes with the proper operation of the pump by forcing the necessary lubricating liquid film away from the contact surfaces of at least a portion of the pump rotor and stator. Consequently, it will be seen that dry operation in at least a portion of the pump can occur even during the pressurizing period of the well and it is therefore equally important that the pump be protected from overheating during such pressurizing periods. By reason of the temperature responsive control scheme described herein the pump is protected against overheating during all periods of operation of the device and regardless of the cause of overheating Although the invention has been described with particular reference to a single specific embodiment thereof, it will be understood that various modifications and equivalents may be resorted to without departing from the scope of the invention as defined in the appended claims.

1 claim:

1. in combination, a pump of the positive displacement progressing cavity type having elongated helical stator and rotor members, at least one of said members having a resilient surface portion contacting the other member and in pumping relation therewith, said surface portion having a tendency to adhere to the other member when overheated and said pump having a tendency to overheat unless operated with an adequate supply of working material in the liquid state for proper lubrication of said rotor and stator members, an electric motor operatively connected to the pump, conductors connected to said motor for supplying electric current to the motor, magnetic switch means interposed in said conductors for controlling the supply of current to the motor, a source of electric current for energizing said switch means, and a thermostat attached to said pump and connected in circuit with said source of electric current for energizing and deenergizing said switch means in response to changes in pump temperature below and above a predetermined temperature range whereby to prevent overheating and consequent damage to said resilient surface portion.

2. In combination, a pump of the positive displacement progressing cavity type having elongated helical stator and rotor members, at least one of said members having a resilient surface portion contacting the other member and in pumping relation therewith, said surface portion having a tendency to adhere to the other member when overheated and said pump having a tendency to overheat unless operated with an adequate supply of working material in the liquid state for proper lubrication of said rotor and stator members, an electric motor operatively connected to the pump, a main circuit including conductors connected to said motor for supplying electric current to the motor and magnetic switch means interposed in said conductors for controlling the supply of current to the motor, and an auxiliary circuit for energizing and deenergizing said magnetic switch means, said auxiliary circuit including a source of energizing current, a thermostat attached to the pump, and a manual switch all connected in series with said magnetic switch means for energizing and deenergizing the latter in response to changes in pump temperature below and above a. predetermined temperature range whereby to prevent overheating and consequent damage to said resilient surface portion.

3. in combination, a pump of the positive dis 1. merit progressing cavity type having elongated stator and rotor members, at least one having a resilient surface portion contacting the other mem er and in pumping relation. therewith, said surface portion having a tendency to adhere to the her when overheated and said pump having a ten overl eat unless operated with an adequate supply of working materia in the liquid state for proper lubrication of said rotor and stator members, an electric motor opcratively connected to the pump, a source of electric current, conductors connected to said source and to said motor for supplying current to the motor, switch means interposed in said conductors for controlling the supply of current to the motor, electrical. energizing means for said switch means, means for supplying current to said en crgizing means from said source, and temperature responsive means attached to the pump and connected to said energizing means for controlling the operation of said switch means in response to the temperature of the pump whereby to prevent overheating and consequent damage to said resilient surface portion.

4. in combination, a pump of the positive displaceprogressing cavity type having elongated helical stator and rotor members, at least one of said members having a resilient surface portion contacting the other m mber and in pumping relation therewith, said surface portion having a tendency to adhere to the other member when overheated and said pump having a tendency to overheat unless operated with an adequate supply of working material in the liquid state for proper lubrication of said rotor and stator members, an electric motor opcratively connected to the pump, a source of high voltage electric current, conductors connected to said source and to said motor for supplying current to the motor, switch means interposed in said conductors for controlling the supply of current to the motor, electrical energizing means for said switch means, a transformer connected to said source and to said energizing means for supplying current to the latter at a reduced voltage, and temperature responsive means attached to the pump and 3 connected to said energizing meansfor controlling the operation of said switch means in response to the temperature of the pump whereby to prevent overheating and consequent damage to said resilient surface portion.

5. in combination, a pump or the positive displacement progressing cavity type having elongated helical stator and rotor members, at least one of said members having a resilient surface portion contacting the other member and in pumping relation therewith, said surface portion having a tendency to adhere to the other member W 1 o V and said pump having a tendency to overheat unless operated with an adequate supply of Working material in the liquid state for proper lubrication of said rotor and said stator members, an electric motor operatively connected to said pump, conductors connected to said motor for supplying electric current to the motor, 5 tch means interposed in said conductors for controlling the supply of electric current to the motor, electric means for actuating said switch means, and temperature resp0nsive control means attached to said pump and connected in circuit with said electric means for actuating said switch means in response to changes in pump temperature above and below a predetermined temperature range whereby to prevent overheating and consequent damage to the said resilient surface portion.

6. The combination of claim 5 further characterized in that said stator member has a resilient lining.

References (Iited in the file of this patent UNITED STATES PATENTS 1,426,206 Lybeck Aug. 15, 1922 2,028,407 Moineau Jan. 21, 1936 2,189,356 Briggs Feb. 6, 1940 2,258,371 Wernert Oct. 7, 1941 2 75,066 Ottenbourg Mar. 3, 1942 2,275,502 Broadhurst Mar. 10, 1942 2,344,946 Landon Mar. 28, 1944 2,403,688 Smith July 9, 1946 2,409,688 Moinea'u Oct. 22, 1946 2,466,440 Kiekhaefer Apr. 5, 1949 2,512,765 Byram June 27, 1950 2,688,719 Busquet Sept. 7, 1954 2,707,440 Long et al. May 3, 1955 FOREIGN PATENTS 392,116 Great Britain May 11, 1933

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