US2940395A - Control means for pumping apparatus - Google Patents

Description

June 14, 1960 R. H. HILL CONTROL MEANS FOR PUMPING APPARATUS Filed Jan. 20, 1956 MAGNETIC K: swzrcH' 1 MOTOR THERMOSTAT T 16 F mausnc o d SWITCH":

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7 v. 4 a W 33 a m 4 i A 2 w m 2 w R J 3 m 7a m. w 6 0% a 1 9 j 6 O- A IIHIIIII r 6 1 mV 3 Wm G W United States Patent "ice CONTROL MEANS FOR PUMPING APPARATUS Robert H. Hill, Fort Wayne, Ind., assignor to Perfect Circle Corporation, Hagerstown, Ind., a corporation of Indiana Filed Jan. 20, 1956, Ser. No. 560,459

3 Claims. ((11. 103-25 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. 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 iscumbersome' and time consuming and involves substantial expense. In fact, in ma y cases whereth'e productionof 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 of the well in a very convenient and reliable manner andat 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 orother 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 wellduring the pressurizing periods. Reference is made to my United States Patents 2,737,119 and 2,739,650for various details of the pumping apparatus.

The present invention is particularly concerned with an improved and highly. economical circuit arrangement for preventing overheating of thepump or motorof the apparatu's. As an: hereinafter appear, the preferred type 2,940,395 Patented June 14, 1960 of 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. Otherwise, the pump and its motor will overheat with the danger of serious damage to the operating parts.

Accordingly, a primary object of the invention is to provide novel and improved circuit arrangement in a control means for a 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 or motor of a pumping apparatus for use in oil Wells and the like.

An additional object of the invention is to provide a novel circuit arrangement for a temperature responsive control means in a pumping apparatus for use in oil wells and the like.

Other objects and advantages of the invention will become apparent from the subsequent detailed description taken in conjunction with the accompanying drawing wherein:

Fig. 1 is a diagrammatic representation of the essential elements of an electrical circuit for a pumping apparatus and a temperature responsive control means embodying the features of my invention;

Fig. 2 is a modification of the arrangement shown in Fig. 1; and

Fig. 3 is still another modification of the circuit.

As hereinbefore 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 sections and a reversible pump section connected in end-to-end relation for fluid flow therebetween. A suitable fluid 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 purgingmaterial, 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 elfectively 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 downwardly into the well under pressure, the reservoir space is sealed atits 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 is of larly, the invention contemplates the use of the progressing cavity type pump known commercially as the Moyno pump and comprising an elongated female helical member whichkonstitutes the stator of the pump I and an elongated male helical member mounted in ;the female member and constituting the rotor of the pump. The outer member 'o-rstator is provided with one helical thread more than the inner member or-rotor, and the two membets are soarranged 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 dilference in the number of threads on each member w -hen the rotor 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 etfect. Reference is made to ULS. Patents Nos. 1,892,217 and 2,028,407 fora detailed consideration ofthe theory and operation of the progressing cavity type of pump. A pump of the progressing cavity type is particularly desirable because it is capable o'f'generating very high pressures when used in a reversible orcyclic manner as described above. However, the progressing cavity type pump isralso extremely valuable for use merely in pumping oil out of the well because of its unusually effective pumping action and because sand or other solids in the fluid being pumped do not cause undue wear or operating difficulties in a pump of this type.

Referring first to Fig. l of the drawing, a pump of the foregoing type is illustrated fragmentarily and comprises a tubular conduit 14} constituting the outer portion of the pump stator. The interior of the tube is provided with a helical lining 11, 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 11 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 (not shown) with the reversible electric motor of the apparatus indicated diagrammatically at 13. V

A control means is provided for stopping the operation of the apparatus when the flow of oil or other liquid through the pump reaches an undesirably low rate or ceases entirely so that the pump or motor or both tend "tooverheat. 'In its preferred form the control system includes a temperature responsive element attached to the pump or motor or both, 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 foropening and closing the switch mechanism in response to predetermined variations in the temperature of the pump or motor; As' will hereinafter appear, there are a number of different conditions which can arise in an oil well during'eithcr the production or pressurizing periods which require the provision of a control system of the present type in order. to avoid overheating.

In the embodiment of the invention illustrated in Fig. '1 of the drawing, the temperature responsive device com- .pr'ises a thermostat 14 mounted on or attached to the pump, in this case to the outside of the conduit 10. The line terminals or conductors for supplying electric current to the motor 13 are designated at 16, 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 motor 13 .by means of suitable leads or conductors 21, 2 2, and 2.3. ilt will be understood that the magnetic switch 19 includes i 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 13 is accomplished by means of a separate electrical circuit which may utilize the same 'or a different source of electrical current as the motor 13.

In many cases, the motor 13, the switch 19, and the thermostat 14 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 17 and 18, respectively, which may provide a current of 440 volts. The low voltage or output side of the transformer 24, which may provide a current ofllO volts, is connected by a lead 28 tojthe 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 primary novel feature of the present invention resides in the circuit connections between the energizing means for the magnetic switch 1-9 and the thermostat 14. It will be understood that the transformer 24 and the magnetic switch 19 are normally located at the ground level, while the motor 13 and the thermostat 14 on the pump are located adjacent the'b'ottom of the well. Accordingly, the normal method of including the thermostat 14 in the circuit would be toextend two additional wires from the transformer output and the switch energizing means at the ground level directly to the thermostat 14 at the bottom of the well. However, I have found that with a poly-phase motor of the character herein employed, it is possibleto eliminate one of 'thesewires by using a lead 29 to connect the transformer output to the upper end of one of the motor conductors 23 at the ground level and interconnecting thelower end of the same motor conductor 23 at the bottom of the well with the thermostat 14 by means of a short connecting lead 31. 'The circuit is completed by a lead 32 extending to a single pole single throw manual control switchjfatalso located at the ground level) andalead 34 connecting the switchfiii with the thermostat '14-. Thus, it will be seen thatthe'motor conductor 23, serves a dual function in that it"supplies current to 'themotor and also comprises anlimportant portion of th th rm t t i oo thorsby os ltin in s tan tial economy and simplification of the circuit. In 'a deep well,]the resultantsimplification and economy by eliminating one wire extending frfom the ground to. the 7 of rotation. If for any reason the pump should overheat duringoperation, as hereinafter explained; .the exicessive temperature will be detectedby the temperative responsive element or. thermostat 14 with the resultthat the switch energizing circuit is disrupted and consequently. the energizing. means of the magnetic switch 19 is deenergized. Upon deenergization of the switch 19, it will beunderstood that the switch mechanism automatically biasedto' 'open position so that'the motor cir- The operation of the .device as described above is as cuit is interrupted and the operation of the pump is stopped. In other words, the thermostat 14 operates to stop ther'notor and pump in the same manner as can be accomplished by operation of the hand switch 33. When the pump cools down sufficiently, the thermostat 14 automatically closes to re -establish the energizing circuit of the magnetic switch 19 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 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 the present invention in effect provides a continuous detection of the external temperature of the stator tube 10 and thereby prevents any danger of overheating. As soon as the pump temperature exceeds the upper limit of the thermostat setting, the thermostat disrupts the energizing circuit of 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 be understood 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 up during operation. In the event that substantially no liquid is being pumped 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, now Patent No. 2,739,650, I have described and claimed a specific means for rapidly releasing this accumulation of high-pressure 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 herein 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 oilwell, 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 sufliciently 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.

A modification of the invention is shown in Fig. 2 wherein the thermostat, designated at 36, is mounted on or associated with the motor 13 instead of the pump. As will be understood, the various conditions heretofore described which may result in overheating of the pump will also necessarily result in overload operation and overheating of the motor 13. In addition, overheating of the motor 13 for entirely different reasons may also occur. In either event, the thermostat 36 will interrupt the motor circuit in the same manner as described in connection with Fig. 1. The same reference numerals are used in Fig. 2 to indicate identical parts, and it will be noted that the dual function of the motor lead 23 is also employed in this modification of the invention.

In Fig. 3 I have illustrated still another modification which combines the features of Figs. 1 and 2. Two thermostats 37 and 38 are utilized in series, the thermostat 37 being mounted on the pump stator 10 and the thermostat 38 being mounted on the motor 13. A line 39 interconnects the two thermostats, and the circuit is completed by the line 34 from the thermostat 37 to the switch 33 and a line 41 from the thermostat 38 to the lower end of the motor lead 23. With this arrangement complete and direct protection is provided for both the pump and the motor.

Although the invention has been described with particular reference to certain specific embodiments thereof, it will be understood that various other modifications and alternative arrangements maybe resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. In combination, a. pump unit, an electric motor unit operatively connected to said pump unit, said units being adapted to be disposed adjacent the bottom of a well,

means. including a plurality of power conductors adapted to extend downwardly from the ground level to the motor unit for supplying current thereto, control means interposed in said power conductors and adapted to be located at the ground level for controlling the supply of electric current to the motor unit, and a' control circuit torsaid control means including a transformer having a primary winding "adapted to be connected to a source of alternating current and a secondary winding connected in said control circuit as ,an energizing source therefore, a

temperature responsive device attached to said motor, a

control conductor connecting said control means to said temperature responsive device, a manually operable switch connected in'series in said control circuit and located at ground level, a connection between said. control means and'one of said power conductors at the ground level, and means connecting said temperature responsive device and said one power conductor adjacent the bottom of the well, the inclusion of said one power conductor in said control circuit thereby eliminating the need for extending an additional control conductor from p the ground level to the temperature responsive device at the bottom of the well.

2. In combination, a pump unit, a polyphase electric motor unit'operatively connected to the pumpjsaid pump unit and said motor unit being adapted to be disposed adjacent the bottom of a well, means comprising a plurality of power conductors adapted to extend downwardly from the ground level to the motor unit for supplying electric current to the motor unit, switch means interinterconnecting said thermostat and saidelectrical means,

and a manually operable switch in series in said control conductor and located at ground level, said thermostat actuating said electrical means in response to changes in temperature .of said motor above and below a predetermined temperature range, the inclusion of said one power conductor in the energizing circuit thereby eliminating the need for extending an additional control conductor from the ground level to the thermostat at the bottom of the well. A r

3. In combination, a pump unit, an electric motor unit operatively connected to said pump unit, said units being adapted to be disposed adjacent the bottom of a well, means including a plurality of conductors adapted to ex. tend downwardly from the ground level to the motor unit for supplying current thereto, control means interposed in said conductors and adapted to be located at the ground level for controlling the supply of electric current to the motor unit, and a control circuit for said control means including transformer means connected for energizing said circuit, a pair of temperature responsive devices each attached to one of said units, a connection from said control means to one'of said devices,

means connecting said devices in series, a connection thetween said control means and one of said conductors at the ground level, a manually operable switch located at posed in said power conductors for controlling the supground level and connected in series in said circuit, and a connect-ion between the other of said devices and said one conductor adjacent the bottom of the well, the inclusion of said one conductor in said control circuit thereby eliminating the need for extending an additional conductor from the ground level to the temperature responsive device at the bottom of the well.

References Cited in the file of this patent UNITED STATES PATENTS 1,610,726 Arutunofi Dec. 14, 1926 2,463,935 Fish Q Mar. 8, 1949 2,518,597 Brooks Aug. 15, 1950 2,756,380 Diebold July 24, 1956 2,778,313 Hill 'Ian. 22, 1957

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