US3105443A

US3105443A - Automatic shut-off device for pumping wells

Info

Publication number: US3105443A
Application number: US87191A
Authority: US
Inventors: Paul H Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-02-06
Filing date: 1961-02-06
Publication date: 1963-10-01
Anticipated expiration: 1980-10-01

Description

Oct. 1, 1963 P. H. JOHNSON 3,105,443

AUTOMATIC SHUT-OFF DEVICE FOR PUMPING WELLS Filed Feb. 6, 1961 3 Sheets-Sheet 1 PAUL H. JOHNSON,

INVENTOR.

ATTORNEY Oct. 1, 1963 P. H. JOHNSON 3,

AUTOMATIC SHUT-OFF DEVICE FOR PUMPING WELLS Filed Feb. 6, 1961 3 Sheets-Sheet 2 PAUL H. JOHNSON},

' INVENTOR.

ATTORNEY Oct. 1, 1963 P. H. JOHNSON AUTOMATIC SHUT-OFF DEVICE FOR PUMPING WELLS 5 Sheets-Sheet 3 Filed Feb. 6. 1961 NOT | I r I I I l 0m Ev NV NN Q R H1 0 o J T H L Y m P m United States Patent 3,105,443 AUTGMATIC SHUT-GEE DEVICE FUR PUMPHNG WELLS Paul H. Johnson, Tulsa, 01:121., assign'or of fifty percent to .lames R. Head, Tulsa, Okla. Filed Feb. 6, 1961, Ser- No. 87,191 2 Claims. (Cl. 103-12) This invention relates to an automatic shut-cit device for use with the power operated pumping systems. In particular, it relates to a shut-off device for use with oil well-type pumping units.

Briefly, this invention relates to a shut-oft control apparatus which is sensitive and responsive to changes in pumping fluid flow. In pumping an oil well with an electric motor power source, a substantial period of no fluid flow is indicated by suitable mechanical movement. This movement changes the induced voltage in an electrical time delay and relay circuit to stop the electric pumping motor. Inclusive of this invention is the shutoff of an internal combustion engine power source by grounding the ignition circuit in the aforesaid period of no flow, or the shutting-oil of. bottom hole motor driven centrifugal pumps.

One method of lifting oil from the bottom of a Well to the surface is accomplished by what is termed: mechanical lift. Generally, mechanical lift involves the use of reciprocating plunger type pumps, classified into tubing pumps and rod pumps. In both cases, sucker rods are used to transmit the reciprocating motion from the surface to the pump. The upper end of the sucker-rod stringterminates with a polish rod which is normally of larger diameter than the sucker rods, and is finished to reciprocate through a stufiin'g box. The polish rod is usually made of a high grade polished steel or if corrosive conditions are present it may be of Monel metal, \OT bronze. The stuffing box is packed with soft rubber to permit some side movement of the polish rod and to seal-ofif the flow of oil. Transmission of power to the sucker rods is accomplished by changing the rotary motion of the prime mover to the reciprocating motion of the rods and pump through a gear 'box, crank-arm and walking beam.

The use of electricity as the power supply source for pumping wells is of current interest. Motors'which supply the power for pumping are either of the slip-ring or squirrel cage types and range upwards of 75 horsepower or more. The use of a bottom-hole electric motor and centrifugal pump unit is also of current use in the oil industry which, of course, eliminates the use of sucker rods.

Many wells which are pumped electrically are controlled by a time clock assembly which is set to pump the well at particular intervals in order to produce the greatest amount of oil per day. This pumping interval will depend to a great extent upon the characteristics of the formation from which the production fluids are obtained, the porosity, permeability, the size of the formatic-nal cavity, the size of pump used, and the number of strokes per second, etc.

Thereare many wells in production today where, if the pumping unit were allowed to operate continuously, all of the fluid or oil within the well is removed before additional oil has had time to enter the well. In this condition the well has pumped oil? and the pumping unit should be shut-off. Since the occurrence of the pumped ofli condition can occur at any time, it is inconvenient to rely upon manual operation to shut down the unit.

. Accordingly, it is desirable that some form of automatic shut-off be available, separate and apart from manual operation and responsive to changes in fluid flow. Without a shut-off device, the pumping unit continues to operate with undue wear upon all parts of the pumping sys 3,ifi5,443 Patented Get. 1, 1963 tern. Lubrication of the polish rod in its reciprocation through the stufling box occurs from the produced oil. Absence of the oil results in wear not only on the stufiing box packing rubbers but also upon the polish rod. In some instances the sucker rods and pump are designed for use under loaded conditions, i.e., when the tubing is filled with liquids. Without the load, the rods buckle and wear against the production tubing. This will cause eventual leaks in the tubing and/or parting of sucker rods, requiring a fishing job.

Additionally, when the sucker rods are not lifting a load of fluid, the counterbalance weights on the walking beam or crank arm will be too great, causing an unbalanced condition, placing increased stress on the pumping unit and primemover, further resulting in waste of fuel or electricity.

In the prior art there are many types of pumping unit shut down devices such as inertia-type switches actuated by motion changes in the walking beam or sucker rods. Time switches or stroke counter operated switches have also been taught as automatic shut-off apparatus. However, these devices for the most part, are not actuated by changes in fluid flow.

In the design of an oil well shut-off device to be operable by the absence of fluid flow, one outstanding problem is present. The pumping of an oil well with sucker rods is generally by reciprocation. This induces a pulsating flow to the produced fluids. In most flow controlled switches this must be compensated tor, else the switch will oscillate on each stroke of the sucker rods.

Accordingly, it is an object of this invention to disclose an automatic shut-off device for pumping wells, which overcomes the objections to the prior art devices.

It is another object of this invention to disclose a shutoff device for pumping wells which is responsive to changes in the flow of fluid being pumped.

A further object of this invention is to disclose an automatic shut-oft device which is adaptable to all forms of power operated pumping systems.

It is a further object of this invention to disclose an automatic shut-off device which is sensitive to changes in flow of fluid by mechanical movement changing the mutual inductance voltage of a circuit.

A still further object of this invention is to disclose an electrical time delay circuit responsive to changes in in- V ductance voltage within said circuit.

Other objects of this invention will be more apparent and more readily understood when reading the disclosed description, operation, and claims when taken in conjunction with the following illustrations of which:

FIGURE 1 is a diagrammatic representation of an electrically powered beam-type oil well pumping unit in conjunction with the automatic shut-olt control of this invention;

FIGURE 2 is a cross-sectional view of the flow responsive apparatus for use according to this invention;

FIGURE 3 is a sectional View taken along the line 3-3 of FIGURE 2; and

FIGURE 4 represents a circuit diagram for use in conjunction with the shut-off device of FIGURE 2. and a typical pumping motor.

reciprocating motion through a crank-arm and counter-- weight 20, to pitman arm 22 and walking beam 24 piv oted on A firame 26 at the bearing represented at 28. Polish rod 34) is attached to the walking beam and horse head 31 by hanger assembly 32. The polish rod is attached to sucker rod 34 positioned in production tubaso-ft iron or mild steel core. 7 v V I 7 As diagrammatically shown, a lift-type fiapper' or plunger 50 is attached .to a rod 52. In the no-fiow posiing 36 to reciprocate the bottom hole pump, not shown,

within casing 37. Well fluids pass up through the production tubing 36 to flow T38 and thence into line 48.

' Fluid is prevented fromleaking past the polish rod 50 by meansof a stuffing box 42 which contains rubber packing. The produced fluid passes through line 4-0 to separator and storage vessels not shown. Arranged'near the well head and made a part of the flow line is the flow responsive shut-E device of this invention, represented gen- 7,

orally at 44. To prevent back-flow of produced fiuids, a check valve isn'ormally provided in the flow line. As will be readily understood from further reading of the specifications, the apparatus ofthis invention may be combined with a check valve. Automatic shut-ofi control of the pumping unit is provided by the associated electrical circuit 46 more fully described in FIG. 3.

FIG. 2 represents a detailed and diagrammatic cross-.

sectional view of the flow responsive shut-cit device of this invention. The shut-0d device it is connected to fiow line 40 in such manner that flow of fiuids will pass therethrough and perform some form or mechanical movement. Typically, this movement is derived from a lift type valve or from the flapper of a check valve,

which upon the cessation of fiuid flow will move to a closed position. Moyable'with the valve element will be tion plunger 58 will rest on seat 53. During movement of oil or other pumped fluids the plunger will lift and remain in that position, with the oil bypassing into the rod reciprocates within a non-magnetic tube 55 connected to lower frame 57 which is sealed at the upper end with cap 56. Surrounding the nonmagnetic tube are primary and secondary coils 58 and'60 respectively. The appaheld by fas- V ratus is enclosed by a protective cover 62, tener 63. V

In effect, the primary and secondary coils represent a transformer. That is, the energy is supplied to the trans- V former through the primary coil 58, with the energy delivered by the transformer by mean-s ot the secondary coil 60. This transfer is made through the medium of the, induced magnetic field through the iron rod 52.

'Voltage is applied to primary coil 58 through leads 64 tabs for each minutes of the dial. This means that with one'tab pulled out, the pumping motor circuit will stay closed for at least that minimum 15 minutes. At the instant the timer acts to close micro-switch 106, actuator 86 is energized closingj the contactor 84 which energizes motor 10.

In the typical use of the apparatus of this invention, once the pumping cycle. has been started by clock 88, the pumping operation will. not shut off at the end of the 'pre-set period of the clock 88, as long as fluids such as,

oil and gas and water are being pumped; In that instance, after the pre-set minimum time of clock 88 has elapsed iron rod 52 is within the inductance field of secflow line 40 in the direction shown by the arrows. The

ondary coil 60 inducing voltage from coil 5-8 to the circuit of relay 96. The relay holds the circuit closed through lead 102, contacts 98 and 100, placing voltage on holding coil 86.

The circuit of leads 68 and '70 has abuilt-in tirne delayto compensate for pulsating fiuid flow which raises 7 and lowers rod 52. The induced voltage charges high capacity condenser 94"which tends to maintain a constant voltage across relay 96 even for variations in voltage caused by the, pulsation'of rod 52. Only with complete cessation of flow will the capacitor 84 sutiiciently discharge to release the relay and open the circuit at contacts 98 and 100 to shutofl the pumping motor 10. The timerdel ay circuit, in atypical example, uses a selenium' rectifier 92 to convert the alternating induced volt- Oocndenser 94 was rated at age into direct current. 1000 mid. at 25 workingvolts (w.v.). high impedance type (10,000 ohms).

In the operation :of a typical oil well installation utilizing the automatic shut down method of this invention, clock Relay 96 was a 881will normally be set'to turn the well on at least once a but preferably severaltimes per day.' The pumping periods will usually be set at equallyspaced periods throughout the day. For instance, the pumping cycles maybe desired to be set for each six hour period so that the well is turned on to pump four times per day.

and 66. Induced voltage from secondary coil is car:

I ried by leads 68 and 70. The coils are spaced from each other and from the tube 55 by insulation '71.

The schematic circuit diagram of FIG. 4 is a broad representation of one system for use according to this invention. Line voltage is carried to the pumping motor by leads'80 and 82. A circuit interrupter'and contactor device is represented in both leads at 84. The interrupter is energized thus closing the circuit, by means of solenoid or holding coil 86. Connected across leads and 82 is a-clock motor 88 energized through

leads

85 and 87

Leads

64 and 66 carry line voltage which is stepped down'by using transformer 90 with the lower voltage carried by 64 and 667 to the primary coil 58.-

Secondary coil 60 is attached to leads 68 and-'70 to a circuit which includes a rectifier 92 in onelead. A high capacitance condenser 94 is across leads68 and '70 between rectifier 92 and a high resistance relay 96 also,

connected'across leads 68 and 70. The relay functions to openand close contacts98 and 100 connecting through

leads

102 and 104 respectively. Connected across leads 7 held closed may be varied according to the desires of the operator.

Assuming that switch 106 isheld closed by clock 88 for fifteen minutes, at the end of this period switch 106 will open. During this fifteen minutes of pumping, if the well is functioning properly, the reciprocation of 'rod 34 will cause produced fluid to 'flow through line 40. On each upstroke of sucker rods 34 a surge of Y fluid flows through line 40, up through opening 53, rais- 102 and 104 is a micro switch 10.6 operable by time clock 88. Lead 104 attaches to one side of the holding coil 86, the other side of theholding coil 86 being directly connected to line voltage 82; Lead 102 is attached to the other line voltage lead80.

Well conditions will normally dictate at what time clock 88 is to be pre-set to close the circuit and begin pumping operations. .The typical time clock presently used in the 'oil industryhas a 24 hourdial with pull-out ing flapper 50, and rod 52. As rod 52 israised increased voltage is induced in secondary coil 60. This increased voltage is altered by rectifier 92 into a DC. voltage which charges capacitor 94 and closes relay 98.

" This places'voltage on holding coil 86 even though clock switch 106 subsequently opens. 1

On the down stroke of sucker rods 34 no production will fiow through line 40 and flapper 50 will return to its seat 53. In this position rod 52 will be lowered and the voltage induced in secondary coil 60 will be reduced. During the time a'reduced voltage exists in'coil 60 the direct voltage applied tocapacitor $4 willbe reduced and capacitor 94 will begin to discharge through high im-' pedance relay 96. During this period of discharge as long as the voltage across rela'y96is sufficient, contacts 100 of the relay will remain closed. Before condenser 94 has discharged sufficiently so that the voltage across relay 96 is low enough to permit relay 98 to open and break contact 100, the next stroke of sucker rods 34 occurs,

forcing more fluid through line 54), raising flapper 50 and rod 52 and introducing a new surge of voltage to again'renew the charge on capacitor 94.

Thus it can be seen that after the fifteen minute period of closure of switch 196 by clock 98 the production of fluid by the reciprocation of rod 34 will maintain relay 98 closed, paralleling switch 1% with contact 190 so that holding solenoid 85 remains closed which in turn maintains energization of motor 10. As long as the well is producing fluid in sufficient quantities so that on each stroke rod 52 is raised sufliciently to recharge capacitor 94, the well will continue to pump.

When all of the fluid within the well is depleted by the pumping action, on each up stroke of sucker rods 34 the amount of fluid raised will be reduced. As the total fluid produced on the up stroke of sucker rods 34 diminishes, rod 52 will not rise as high into secondary coil 6t and the voltage induced in secondary coil 69 and subsequently applied across capacitor 94 will diminish. As production continues to decrease, the point will be reached where rod 52 does not rise sufliciently to charge capacitor 94. Relay 96 will open breaking contact point 189, ale-energizing holding solenoid 86 and motor 19. At this point the well has automatically shut itself off and will remain in a shut off position until the next pumping cycle is started when clock 86 closes switches 186.

Clock 86, as outlined in FIGURE 4, serves only as a starting devioe and the automatic shut down system according to the principles of this invention serves as a stopping device.

In practice a capacitor 94 having a capacity of one thousand microfarads at twenty-five working volts was used in conjunction with a relay as having an impedance of ten thousand ohms. Transformer 9t reduced the voltage on primary coil 58 to 25 volts. With primary and

secondary coils

58 and 64 having approximately the same number of turns, it was found that a time delay of approximately .15 seconds of relay 96 was obtained. In a pumping unit operating at .15 strokes per minute, a surge of fluid through line 40 occurs each four seconds. Thus, with a 15 second time delay of relay 96, meaning that rod 52 need only rise once each 15 seconds to keep the relay 96 closed, it can be seen that if no fluid is produced on three successive strokes of sucker rod 34 the well will shut down.

These are merely typical examples and it can be seen that a wide variety of time delay may be obtained. If an increased time delay is required capacitance 94 may be increased, or the impedance of relay coil 96 may be increased.

If additional time delay is required, contact 100 may be utilized to actuate a supplemental time delay device, such as a thermal, pneumatic, or clock type of time delay devices, to produce any desired time delays up to several minutes or even hours. In a well which experiences frequent gas surges it may be desirable to provide a time delay of one minute or even a great deal longer upon the succession of fluid flow before the well is shut down.

The only movement of the device which takes place on each stroke of sucker rod 34 is the rising and falling of rod 52. Relay 98 remains closed during the pumping cycle until it opens to shut off the pumping cycle. The detection of the pulsating flow of fluid through line 40 takes place on the rising and falling of the charge of capacitor 94. In this way there are no make and break switch contacts to wear out.

Although this invention has been described as it particularly pertains to shutting down a reciprocating pumping well, the mechanism is applicable to shutting down other fluid flow devices wherein it is desired to have a time delay between the succession of flow and the de-energization of the prime mover.

Although this invention has been described with a certain degree of particularity, it is. understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction, combination and arrangement of parts may be resorted without departing from the spirit and scope of the invention as hereinafter claimed.

I claim:

1. An automatic shut off control for an oil well pumping system, said oil well pumping system having a prime mover ior actuating a reciprocating bottom hole pump mechanism of the type that produces pulsating fluid flow through a conduit out of said well, said shut-ofl control comprising, in combination:

a plunger member responsive to said conduit;

a transformer having a primary and a secondary winding, said windings supported in proximity to each other;

means supplying alternating electrical current to said primary winding;

a core member actuated by said plunger and movable within said winding, said core member varying the mutual inductance between said windings according to the position thereof relative to said winding whereby the mutual inductance and thereby the voltage induced in said secondary winding at any instant is determined by the position of said plunger which in turn is determined :by the quantity of fluid flowing through said conduit from said well;

a relay means having continuity with said secondary winding, said relay means having switch means for controlling power supplied to said prime mover; and

time delay means with said relay means whereby said relay switch is actuated after a predetermined time to deenergize said prime mover upon the cessation of said pulsating fluid flow.

2. An automatic shut-cit control for an oil well pumping system according to claim 1 wherein said time delay means includes;

a rectifier means in series with said relay means; and

a capacitor in parallel with said relay, said relay being of the high impedance type whereby discharge of said capacitor after the voltage output of said secondary coil drops below a value suficiently to maintain said relay in an energized state keeps said relay energized for a predetermined length of time.

References fitted in the file of this patent UNITED STATES PATENTS flow of fluid through 1,980,799 Hardesty Nov. 13, 1934 2,472,389 Von Stoeser June 7, 1949 2,550,093 Smith Apr. 24, 1951 2,853,575 Reynolds Sept. 23, 1958 2,927,455 Outterson Mar. 8, 1960 2,947,931 Hubby Aug. 2, 1960 2,953,659 Edwards Sept. 20, 1960 FOREIGN PATENTS 168,514 Switzerland June 16, 1934

Claims

1. AN AUTOMATIC SHUT-OFF CONTROL FOR AN OIL WELL PUMPING SYSTEM, SAID OIL WELL PUMPING SYSTEM HAVING A PRIME MOVER FOR ACTUATING A RECIPROCATING BOTTOM-HOLE PUMP MECHANISM OF THE TYPE THAT PRODUCES PULSATING FLUID FLOW THROUGH A CONDUIT OUT OF SAID WELL, SAID SHUTT-OFF CONTROL COMPRISING, IN COMBINATION: A PLUNGER MEMBER RESPONSIVE TO FLOW OF FLUID THROUGH SAID CONDUIT; A TRANSFORMER HAVING A PRIMARY AND A SECONDARY WINDING, SAID WINDINGS SUPPORTED IN PROXIMITY TO EACH OTHER; MEANS SUPPLYING ALTERNATING ELECTRICAL CURRENT TO SAID PRIMARY WINDING; A CORE MEMBER ACTUATED BY SAID PLUNGER AND MOVABLE WITHIN SAID WINDING, SAID CORE MEMBER VARYING THE MUTUAL INDUCTANCE BETWEEN SAID WINDINGS ACCORDING TO THE POSITION THEREOF RELATIVE TO SAID WINDING WHEREBY THE MUTUAL INDUCTANCE AND THEREBY THE VOLTAGE INDUCED IN SAID SECONDARY WINDING AT ANY INSTANT IS DETERMINED BY THE POSITION OF SAID PLUNGER WHICH IN TURN IS DETERMINED BY THE QUANTITY OF FLUID FLOWING THROUGH SAID CONDUIT FROM SAID WELL; A RELAY MEANS HAVING CONTINUITY WITH SAID SECONDARY WINDING, SAID RELAY MEANS HAVING SWITCH MEANS FOR CONTROLLING POWER SUPPLIED TO SAID PRIME MOVER; AND TIME DELAY MEANS WITH SAID RELAY MEANS WHEREBY SAID RELAY SWITCH IS ACTUATED AFTER A PREDETERMINED TIME TO DEENERGIZE SAID PRIME MOVER UPON THE CESSATION OF SAID PUSHING FLUID FLOW.