US2550093A - Oil well control system - Google Patents

Description

April 24, 1951 G. A. SMITH 2,550,093

OIL WELL CONTROL SYSTEM Filed March 15, 1949 2 Sheets-Sheet 1 April 24, 1951 I G. A. SMITH 2,550,093

OIL WELL CONTROL SYSTEM Filed March 15, 1949 I 2 Sheets-Sheet 2 Patented Apr. 24, 1951 UNITED STATES PATENT OFFICE OIL WELL CONTROL SYSTEM Grafton A. Smith, Tulsa, Okla., assignor to Shell Development Company, San Francisco, Calif a corporation of Delaware Application March 15, 1949, Serial No. 81,573

Glaims.

This invention pertains to a system for controlling the operation of oil well pumps, and relates more particularly to an automatic system for the control of electrically driven pumps in wells producing small quantities of fluid.

In many wells, especially during the later stages of their exploitation; the quantity of fluid entering the borehole fromthe formation is often less than that which can be readily handled by the pumping equipment, that is, the volumetric capacity of the pumping equipment installed at the well is such that a sustained operation'thereof results in pumping the well oil or dry; Under these conditions, it is usual to produce such wells by intermittent pumping, so that the fluid is permitted to accumulate in the borehole during pump shut-down periods, and is exhausted from the well during alternate pump operation periods.

Such intermittent operation of the well pumping equipment may be controlled either manually,

off at a time when considerable oil remains in the borehole, thus lowering the efficiency of the pumping operations, or the pumping period may be cut ofi only long after the borehole has been pumped substantially dry, thus increasing the wear on the pumping equipment and wasting power.

It is, therefore, an object of this invention to provide a well-pumping control systemwherein the duration of the pumping period is automatically adjusted to the amount of fluid available for umping from a well during said pumping period.

It is also an object of this invention to provide a well -pumping control system wherein the operation or" the pump is automatically stopped when the fluid in the borehole is depleted;

Another object of this invention is to provide a system wherein each pumping period is started by an automatic time-responsive device, and isterminated by an automatic device responsive to well conditions.

These and other objects of this invention will be understood from the following description taken with reference to the attached drawing,

wherein The main disadvantage of Figure 1 is a diagrammatic sketch illustrating the component parts of the present system;

Figure 2 is a view, partly in cross-section, of

the flow-responsive device and pump shut-off ele-' of a sucker rod string H, the well fluid lifted to 1 the surface being directed to storage through a pipe I2. The sucker rod string II is reciprocated in the well by the oscillating motion of a walking beam it, which is driven, through a pitman l4, crank l5 and speed reducing mechanism It, by a prime-mover ll such as an electric motor receiving its power through leads I8 and I9. It is understood that any suitable type of motor or engine may be used as the prime mover I1, such,

for example as a gasoline engine having its energizing ignition current supplied through leads l8 and I9. f

The control circuit of the pump motor 11 comprises three control switches 20, 2i and 22 that are connected in parallel between the motor I! and a power source 23. Switch 20'is a normally open hand-operated switch which, when closed, places the pump I! in continuous operation. Control switch 2| is normally open being adapted tobe closed by a time-responsive device such :as'

an electric or spring driven clock mechanism 24 of any desired type. For simplicity, this mechanism' is shown in Figure 1 as comprising a rotating wheel or disc 25 provided with a segment adapted to close the switch 21 by contact therewith. It will be seen that the time at'which the switch 2| isclosed and opened can be accurately pre-set or controlled by suitably adjusting the speed of rotation of the-disc 25 and/or the size of the segment 26.

Control switch 22 is normally closed all the time that fluid is being pumped from the well borehole and through the delivery line 2|. Preferably, switch 22 is small in size, such as a microswitch, or a sealed-mercury type switch. The switch 22 is mounted on, and adapted to be actuated by, a flow-responsive controller device 2! which is in turn connected through suitable linkage means to the gate or flapper o'fa check valve 29-inline l2.

As shown inFigure-Z, the flow-responsive conbolts'33 to flanges 34' and 35 in the pipe line I2. Thecheck valve 29 is of the globe type having a 3 vertical-lift gate or disc 35 with a beveled edge 3? adapted to be seated in a beveled edge horizontal valve seat 38 surrounding the valve opening 39. Preferably, a plate 41) of suitable thickness is fixedly secured to or integrally formed on the bottom of the disc 36, said plate Ml having a diameter substantially equal to that of the valve opening 39 and adapted to close said opening 39. A plurality of downwardly-extending guide bars 4! may be secured to the lower side of the plate 45 and disc 36 for guiding said disc into its proper seating position on closing, and for maintaining the disc 38 in a fixed position with regard to the valve opening 39 when the valve is open.

A valve bonnet 42 having a lower flange 43 is secured by bolts 44 to a flange 55 of the valve body 30; A valve stem 46 is secured in either a fixed, or. hinged manner to the top of the valve disc 36, said stem 46 extending upwardly into the bonnet 42. The disc 36 of the check valve is normally maintained in a closed position by a compression spring All that surrounds the valve stem 45 and bears against the top of the disc 36. Compression of the spring mil may be adjusted, without dismantling the valve, by an adjustment screw 48 through the top 9 of the bonnet 52, said screw being adapted-to be fixedly held in place by a lock nut 50. Interposed between said compression spring 47 and screw 48 is a suitable yoke means comprising either a slotted tubular member, ,or a ring and a plate 52 maintained in fixed space'relationship to each other by at least two, and preferably four, spacing bars 63, said yoke means beingpositioned in said valve bonnet s2 so that said spring 4'! and screw 48 bear against the ring 5| anddisc 35, respectively.

'Ahole, 53, drilledthrough the side wall of the bonnet 42 and fitted with abushing or bearing 54,

serves as-bearing means for a horizontalshaft 55 which extends into said bonnet above and vto one side of 55, as seen from Figure 5. A recess 56 -may be drilled in the inner wall of the bonnet 42 diametrically opposite hole 53, said recess 55 serving as bearing means for the end of the shaft 55 positioned within the bonnet 32. The shaft 55 and the tapered and drilled upper end 51 of the valve stem are operatively connected together by a fiat link member 58 having a hole 59 '(Figure 5) through one end, whereby said shaft may pass through said hole 59. The other end of the link 58 is slotted and drilled to fit around the tapered and drilled end 57 of the valve stem 55, the drilled ends of said link 58 and said stem 45 being secured together in hinged relationship by a pin 51! as shown in Figure 2. The link 58 is locked in a predetermined fixed position on the shaft 55,and between the spacing bars 53 of the yoke means, by a set screw 6|. The shaft 55 is suitably packed in a fiuidtight manner around its bearing 54, said packing being held in'place by a packing nut 52 or any other suitable means.

Supporting means for related control equipment may be positioned adjacent the valve 29. In this embodiment, a platform '64 is shown in Figure 2 as being bolted to the flange 43 of the bonnet 42 beneath the extending shaft 55. Carried on said platform 64 are motor means, such as a clock mechanism, spring motor or small electric motor 55 having its shaft 65 coupled, if desired, to the high speed shaft of suitable speed reducing means 61. Fixedly secured to the lowspeed shaft 68 of the speed reducer 61, by a set screw 59, is a ratchet wheel 75 which may be slowly-rotated at any predetermined .speed, say, one revolution per hour. Freely mounted for swinging on said shaft 68 adjacent the ratchet wheel H3 is an actuator or cam H formed with a small lever arm l2 (Figure 3). Due to its shape and loose eccentric mounting on the shaft 68, the cam H has a tendency to swing downward so that its longer and heavier end depends below said shaft. However, as will be explained below, the cam H is normally maintained in a substantially horizontal position by a pawl 13 (Figure 3) carried by said cam and actuated by a spring F4 to engage the teeth of the ratchet wheel 10. Thus, the ratchet wheel 10 and pawl 73 form overriding clutch means or adjustable coupling means between the drive shaft 68 and the actuator H. vents any horizontal movement of the cam H on said shaft 6%.

Affixed to the end of shaft 55 at a predetermined angle, by a set screw 75, is a rocker arm 11 having an extending pin 18 secured to one end. Preferably, the low-speed shaft 68 of the speed reducer is mountedcoaxially with shaft 55 extending from the bonnet 42 of thevalve, whereby the rocker arm ll may be positionedso that its pin 18 extends beneath the cam H to establish contact therewith, as shown .in Figure 2.

Thus, any upward motion of the rocker arm 1T and pin i8 is transferred to the cam H.

The pump cut-off switch 22 is shown in Figures 2 and 3 as consisting of, a switch housing 19, a

through leadsfiz and 83. 'It is realized that any other suitable type of switch may be used and mounted with regard to the above described equipment so that it will be opened by'a predetermined movement of the cam H. Thus, as

shown in Figure 4 a switch 84 of the mercury- I sealed type having leads 85 andBB secured there to may be mounted on the arm??? of a cam88 whereby-any movement of said cam 88 beyond a predetermined point will tilt theswitch 88 so that the mercury contained therein flows to one end of the switch housing thus opening said switch. I

The present pumping system may be put into operation by closing the hand-operated switch 2i! (Figure 1) to start the motor H which causes the pump in the well It to be reciprocated. The l 1 fluid delivered "by the pump surges or flows through the delivery line I2 with every stroke of the pump. Each surge of fluid through the line,

in the direction indicated by the arrow in Figure 2, causes the disc 35 of the check valve to be raised vertically in the valve opening 39. Since there is a plate 40 secured to the bottom of the disc 36, this plate 45 acts as a piston and nofluid starts to flow through the opening valve until the gate has been raiseda distance equal to the of the present device.

As the disc 36 is raised against the compression .7 of the spring 41, the link member 58 is moved upwardrcausing the horizontal shaft 55 to rotate,

for example, in a clockwise direction, when viewing the valve housing from the side of the motor 55. Th rocker arm ll, being fixedly attached i to shaft 55 is also moved in a clockwise direction, ,.;that is, the arm H is moved upwardly so fth'at its pin TBcontacts the cam H and raises it so that A nut T5 at the end of shaft 68 pre-' This serves to comits lever arm 12 is out of contact with the switch spring 8| thus allowing spring-loaded switch 22 to automatically close.

With the switch 22 closed the hand-operated switch 20 may be opened and the motor [1 will continue to operate the pump as long as lever 12 does not contact and open switch 22, the operation being as follows: The cam H is mounted loosely on shaft 68 and its center of gravity is disposed so that it tends to swing counter-clockwise on said shaft. However, the spring-loaded pawl 13 engages the cam H with the ratchet wheel 10, so that the cam can move counterclockwise only together with said wheel, which is adjusted to rotate continuously at some suitable low speed, such as one revolution per hour. As the slow rotation of the wheel 10 tends to bring the lever 12 of the cam TI into contact with switch 22 to open said switch, this tendency is ,counteracted by the action of the pump, which forces a surge of fluid through the check valve 29, raising stem 45 and actuating rocker arm 11 and pin 5'3 to rotate the cam ll clockwise about its shaft whereby the pawl 13 is caused to disengage one tooth on the ratchet wheel and to engage another tooth further up. The cam is thu maintained in a substantially horizontal or any other desired predetermined position by two opposing actions: the continuous slow rotation of the ratchet wheel in one direction, and the intermittent rotation in the reverse direction due to the lifting effect applied by rocker arm 11 and pin 18 every time that the valve 29 operates. However, when the well is dry, and fluid is no longer being pumped through the check valve 29, the valve disc 36 remains closed, and the link 58 and rocker arm 11 no longer operate to counteract the steady rotation of wheel Ill. With the rocker arm Ti and pin 18 at their lowermost position, the cam I! slowly rotates with the ratchet wheel 19 in a counter-clockwise direction until the lever arm 12 of the cam H contacts the spring 8| on the switch 22 and causes it to open shutting off the pump motor I1. I

Instead of being started manually by means of switch 20 the pump motor may be automatically started again, after a predetermined time interval, by the rotating segment 26 of the timeresponsive device which closes the switch 2| and holds it close for the length of time that it takes for said segment 26 to rotate past the switch, say, 10 minutes, whereafter the system is maintained in further operation by the switch 22 in the manner described above.

I claim as my invention:

1. A control system for a well installation comprising a reciprocating well pump, a prime mover for said pump, an energizing electric circuit for said prime mover, and conduit means for the fluid delivered by said pump, said control system comprising a normally closed switch in said electric circuit, adjustable actuator means for opening said switch upon movement to a predetermined position, motor means for continuously moving said actuator means toward said position, check valve means in said conduit means, and transmission means between said check valve means and said actuator means responsive to the periodic opening at each pump stroke of said check valve means by the pump fluid for periodically moving said actuator means in a direction opposite to that of the motion of said motor means, whereby said actuator means are prevented from opening said switch during the delivery of the pump fluid to said conduit means.

2. A control system for a well installation comprising a reciprocating well pump, a prime mover for said pump, an energizing electric circuit for said prime mover, and. a conduit for the fluid delivered by said pump, said control system comprising a normally closed switch in said electric circuit, adjustable actuator means for opening said switch upon movement to a predetermined position, slow-speed motor means for continuously moving said actuator means toward said position, a, check valve in said conduit, a vertical-lift disc in said check valve, a valve stem secured to the top of said disc, and linkage means between said valve stem and said actuator means responsive to the periodic opening of said check valve by the pump fluid for periodically moving said actuator means in a direction opposite to that of the motion of. said motor means, whereby said actuator means are prevented from opening said switch during the delivery of the pump fluid to said conduit means.

3. A control system for a well installation comprising a reciprocating well pump, a prime mover for said pump, an energizing electric circuit for said prime mover, and a conduit for the fluid delivered by said pump, said control system comprising a switch in said electric circuit, said switch being in a closed position while a fluid is being pumped through said conduit, actuator means for opening said switch upon movement to a predetermined position, slow-speed motor means, overriding clutch means coupling said motor means to said actuator means for continuously moving said actuator means toward said position, a check valve in said conduit, a verticallift disc in said check valve and transmission means between said disc and said actuator means responsive to the periodic opening of said check valve means by the pump fluid for periodically moving said actuator means in a direction opposite to that of the motion of said motor means, whereby said'actuator means are prevented from opening said switch during the delivery of the pump fluid to said conduit means.

4. A control system for a well installation comprising a reciprocating well pump, a prime mover for said pump, an energizing electric circuit for said prime mover, and conduit means for the fluid delivered by said pump, said control system comprising a normally closed switch in said electric circuit, a check valve in said conduit means, a vertical-lift disc in said valve, a valve stem secured to the top of said disc and movable therewith, a first shaft extending into said valve above said valve stem, linkage means connecting said valve stem and said shaft whereby a vertical motion of the valve stem is translated into an intermittent rotation of said shaft, motor means mounted adjacent said valve, a second shaft continuously rotated by said motor means, a ratchet wheel fixedly mounted on said second shaft, an actuator freely mounted on said second shaft, said actuator being adapted to open the switch in the electric circuit upon movement to a predetermined position, a spring-loaded pawl mounted on said actuator for engaging said ratchet wheel whereby said actuator is continuously moved toward said position by said ratchet wheel and lever means mounted on said first shaft, said lever means being responsive to the periodic opening of said check valve by the pump fluid for periodically moving said actuator in a direction opposite to that of said ratchet wheel, whereby said actuator is prevented from opening said switch during the delivery of thepump fluid to said conduit means.

5. A control system for a Well installation comprising a reciprocating Well pump, a primer mover for said pump, an energizing electric circuit for said prime moveryand conduit means for the fluid delivered by said pump, said control system comprising first and second switches connected in parallel in said electric circuit, said first switch being normally closed, said second switch being normally open, adjustable actuator means for opening said first switch upon movement to a predetermined position, motor means for continuously moving said actuator means toward said position, check valve means in said conduit, transmission means between said check valve means and said actuator means responsive to the periodic opening of said check valve means by the pump fluid for periodically moving said 8 V actuator means in a direction opposite to that of the motion of said motor means, whereby said actuator means are prevented from opening said switch during the delivery of the pump fluid to said conduit means, and time responsive control means for closing said second switch at predetermined time intervals.

GRAFTON A. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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