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United States Patent 3,918,843
Douglas ,   et al. November 11, 1975

Oil well pumpoff control system utilizing integration timer

Abstract

A valve in the production flow line of an oil well closes a reed switch indicative of fluid being pumped through the line. The switch closure activates a first oscillator whose count is compared with a variable frequency oscillator having a frequency of approximately one half that of the first oscillator. The comparison is made over a given period of time to ascertain the percentage of time the valve has been open and passing fluid. Theoretically, the valve should be open 50 percent of the time because 50 percent of the time is taken on the downstroke of the pumping assembly when no production is occurring. The integrated timer is adjusted to shut down the system when the percentage of time the valve is open drops to the preselected amount, usually equal to or less than 50 percent. In response to the integration timer producing a signal, a shutdown timer is turned on which restarts the cycle after a preselected amount of time. When the system is restarted by the shutdown timer, a pump-up timer is turned on which is adjusted to allow for a desired pump-up time. As the pump-up timer is allowing the system to recycle, the integration timer is reset and the recycling is completed if the requirements of the integration timer are met. Otherwise, the unit is shut down again and the system recycled. A variable electronic scaler is connected to the output of the integration timer which monitors the output signals from the integrator timer. After the preset number of times the integration timer produces a signal, the scaler turns off the whole system. It can then be restarted manually. This provides a safety device for equipment failure such as breaking of the sucker rod. Means are also provided for recording the various timed cycles and also for monitoring the number of signals transmitted to the scaler, thus being indicative of the number of times the system has automatically shut down.


Inventors: Douglas; Bobby L. (Houston, TX), Williams; Robert C. (Spring, TX)
Assignee: Dresser Industries, Inc. (Dallas, TX)
[*] Notice: The portion of the term of this patent subsequent to December 17, 1991 has been disclaimed.
Appl. No.: 05/452,851
Filed: March 20, 1974


Current U.S. Class: 417/12 ; 417/43
Current International Class: F04B 47/02 (20060101); F04B 47/00 (20060101); F04B 49/06 (20060101); E21B 47/00 (20060101); F04B 49/10 (20060101); F04B 49/02 (20060101); F04B 049/00 ()
Field of Search: 417/12,43

References Cited

U.S. Patent Documents
3105443 October 1963 Johnson
3198121 August 1965 Schaub
3424370 January 1969 Law
3814541 June 1974 Dent et al.
3854846 December 1974 Douglas
Primary Examiner: Freeh; William L.
Assistant Examiner: LaPointe; E. P.
Attorney, Agent or Firm: Caddell; Michael J.

Claims



The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for controlling the operation of a well pumping installation including a pump, a motor for operating said pump, and a pumped fluid flowpipe, said well control system comprising:

differential pressure generating and sensing means communicating with said flow of fluid through said flowpipe;

signal means connected to said generating and sensing means and responsive to the differential pressure of said fluid flow in said flowpipe to generate signals indicative of said differential pressure;

means for receiving said signals and for determining the percentage of time during a given time interval that such signals are occurring; and,

means for terminating the pumping operation in the event the determined percentage is less than a predetermined value, said terminating means being responsive to said receiving and determining means.

2. The well control system of claim 1 further comprising:

valve means in said flowpipe arranged to alternately open and close said flowpipe to a fluid flow therethrough;

valve operator means on said valve means responsive to an independent motive-power supply source to operate said valve means between open and closed positions;

regulator means on said operator means for regulating the motive-power supply to said operator means in response to signals from said signal means; and,

means for transmitting said signals from said signal means to said regulator means.

3. The well control system of claim 2 wherein said valve means comprises a pressure operated motor valve, said regulator means comprises an electric solenoid switch, and said transmitting means comprises an electric conduit from said signal means to said solenoid switch; with said motor valve receiving motive-power from an independent pressurized gas supply and said solenoid switch adapted to block the pressurized gas from the independent source and exhaust the pressurized gas on said motor valve.

4. The well control system of claim 1 wherein said differential pressure generating and sensing means comprises:

flow restriction means in said flowpipe for causing a restriction of free flow therethrough;

first pressure transmitting means on the upstream flow side of said restriction means and communicating with the fluid flow in said flowpipe; and,

second pressure transmitting means on the downstream side of said restriction means communicating with said flowpipe;

said first and second pressure transmitting means arranged to transmit to said signal means the amount of pressure in said flowpipe at their respective locations thereon.

5. The well control system of claim 4 wherein said flow restriction means comprises a motor valve, and said first and second pressure transmitting means each comprise pressurizedfluid conduits communicating with the fluid flow in said flowpipe and transmitting pressurized fluid to said signal means.

6. The well control system of claim 4 wherein said flow restriction means comprises a valve, and said first and second pressure transmitting means each comprise pressure sensing elements with electric conduits between said elements and said signal means, said sensing elements adapted to convert fluid pressure in said flowpipe to electronic signals to be transmitted over said electric conduits.

7. The well control system of claim 4 wherein said first and second pressure transmitting means each comprise fluid flow conduits arranged to transmit pressurized fluids from upstream and downstream of said flow restriction means, respectively, to said signal means.

8. The well control system of claim 4 wherein said flow restriction means comprises valve means.

9. The well control system of claim 4 wherein said flow restriction means comprises a restricted flow orifice.

10. The well control system of claim 8 wherein said valve means further comprises a pressure-actuated motor valve.

11. The well control system of claim 8 wherein said valve means comprises a resiliently biased valve having a spring biasing said valve toward a closed position.

12. Apparatus for use in a well control system for sensing fluid flow and controlling fluid flow in the flowpipe of a pumped well, said apparatus comprising:

valving means located in the flowpipe of the well and adapted to alternately open and close the flowpipe;

operating means on said valving means for operating said valving means between opened and closed positions, said operating means adapted to receive a power source from an independent power supply;

first pressure sensing means in the flowpipe upstream of said valving means, said sensing means arranged to sense said upstream fluid pressure and transmit said sensed pressure to another point;

second pressure sensing means in the flowpipe located downstream of said valving means and arranged to sense the downstream flowpipe pressure and transmit it to another point;

signal means associated with said apparatus and arranged to receive said upstream and downstream transmitted pressures and convert said pressures into first and second signals indicative of the differential between said transmitted pressures, said first signal being adapted for transmittal to the well control system, and said second signal adapted for transmittal to said valving means; and,

actuating switch means on said operating means, said switch means arranged to receive said second signal and in response thereto, to control the supply of actuating power to said operating means.

13. The apparatus of claim 12 wherein said first and second pressure sensing means each comprise a fluid flow conduit communicating with the flow in said flowpipe, and said signal means comprises a differential pressure sensing switch receiving pressure applications through said conduits and adapted to convert differential pressures between said conduits into electronic signals.

14. The apparatus of claim 12 wherein said valving means and said operating means comprise a pressure operated motor valve arranged to be closed by application of gas pressure from an independent source; and said actuating switch means comprises means for selectively blocking the actuating gas pressure to said motor valve and simultaneously exhausting gas pressure in the motor valve operator.

15. The apparatus of claim 12 wherein said first and second pressure sensing means comprise electronic pressure switches adapted to transmit an electric signal proportionate to the pressure sensed, and electric conduit means from said pressure switches to said signal means arranged to transmit said pressure generated electric signals therebetween.

16. The apparatus of claim 12 wherein said first and second pressure sensing means comprise fluid pressure conduits; said signal means comprises a pressure differential switch adapted to transmit a signal in response to a differential pressure between the pressures transmitted thereto by said pressure conduits; said valving means and said operating means comprise a motor valve; and said actuating switch means comprises a solenoid switch on said motor valve adapted to selectively cut off actuating power to said motor valve and place said motor valve in position to open.
Description



CROSSREFERENCE TO RELATED APPLICATION

This application is directed to an improvement over that invention disclosed in an original application, Ser. No. 365,881, filed June 1, 1973, by Bobby L. Douglas, now patent No. 3,854,846 entitled "OIL WELL PUMPOFF CONTROL SYSTEM UTILIZING INTEGRATION TIMER."

BACKGROUND OF THE INVENTION

This invention relates to oil wells and more particularly to an automatic well cut-off system for pumping oil wells.

In the production of oil, a well is drilled to the oil bearing strata. At the bottom of the well, a pump is installed to pump oil to the surface of the earth from the pool that gathers at the bottom of the well. A desirable mode of operation is to pump the oil whenever there is oil in the pool and to stop the pumping when there is no oil in the pool.

Advantages of this desirable mode of operation are that the pump automatically reaches its optimum pumping rate with a result in a saving of man hours and equipment. The pump thus operates at a greater efficiency in pump displacement, thereby reducing the total number of pumping hours which in itself results in a saving of power and power cost.

Those in the prior art have long recognized the desirability of control systems for providing such an automatic pumpoff control of oil wells. Examples of such prior art include U.S. Pat. No. 2,550,093 to G. A. Smith and U.S. Pat. No. 2,316,494 to R. Tipton. In the Smith patent, a valve activates an electrical circuit which causes the pump to be shut down after a predetermined time interval in the event the produced oil ceases to flow through the valve. In the Tipton patent, a clock is caused to run in response to there being no produced fluid, thus causing the pump to periodically cycle in response to the well being pumped dry.

These two patents exemplify the prior art in that various means and systems are provided which monitor the lack of produced fluid and which in turn cause the system to recycle in response thereto.

However, the prior art, to the best of my knowledge, has failed to provide a system which provides satisfactory pump-off control for the various oil well pumping facilities having varying conditions and components thereof.

A need therefore exists in the oilfield for a means for controlling the operation of oil well pumps in such a manner that the duration of their pumping periods will be substantially or approximately in accordance with the actual time periods required for the pumping off of the wells. Such a need exists for a means of control whereby an oil well can continue in operation so long as it is pumping oil, but which will automatically stop when it has pumped off the oil, or for breakage, in response to cessation of discharge of oil from the pump.

It is therefore the primary object of the present invention to provide a well pumping control system wherein the pump control is a factor of the percentage of time during which oil is being pumped during a given period;

It is also an object of the invention to provide a new and improved well pumping control system wherein the operation of the pump is automatically stopped when the fluid in the borehole is depleted; and

Another object of this invention is to provide a system having a variable timing subsystem providing greater flexibility than heretofore known in the prior art.

The objects of the invention are accomplished, generally, by a system which utilizes a valve in the production flow line to create an event indicative of produced fluids within the line. The produced event is utilized in conjunction with a timer which determines the percentage of time during which fluid is being produced, and based upon such determination, either allows the system to continue or to shut down. As additional features of the invention, means are provided for the system to recycle and to completely shut down after a predetermined number of recycles.

These and other objects, features and advantages of the invention will be more readily understood from the following description taken with reference to the attached drawing, in which:

FIG. 1 is a diagrammatic sketch illustrating the component parts of the present invention;

FIG. 2 is a view, partly in cross section, illustrating the valve and sensor means utilized to show produced fluid within the flow line;

FIG. 3 schematically illustrates the timing system, partly as a flow diagram, according to the present invention;

FIG. 4 schematically illustrates, partly in block diagram, the electrical circuitry of the invention;

FIG. 5 is a schematic view of a valve type differential pressure sensing means for use in the system;

FIG. 6 is a schematic view of an orifice differential pressure sensing means to indicate flow in the system; and,

FIG. 7 is a schematic view of a spring valve differential pressure sensing means for indicating flow through the system.

Referring now to the drawing in more detail, especially to FIG. 1, a subsurface pump (not shown) located in well 10 is actuated in a well-known manner by means of a sucker rod string 11, the well fluid lifted to the surface being directed to storage through a pipe 12. The sucker rod string 11 is reciprocated in the well by the offsetting motion of a walking beam 13, which is driven through a pitman 14, crank 15 and speed reducing mechanism 16 by a prime-mover 17 such as an electric motor receiving its power through lead 18. It should be appreciated that any suitable type of motor or engine may be used as the prime-mover 17, for example, a gasoline engine having its energizing ignition current supplied through lead 18.

A valve assembly 19, shown in more detail in FIG. 2, is located within the pipe 12 and has an electrical conductor 20 leading from the valve assembly 19 to a controller panel 21 shown in more detail in FIG. 3.

Referring now to FIG. 2, the valve assembly 19 is illustrated in greater detail. This valve assembly is substantially cylindrical in shape and has threaded connections 22 and 23 on opposite ends to facilitate assembly within the flow pipe 12 of FIG. 1. A cylindrical valve housing 24 constructed, for example, of plastic and fabricated perpendicularly to the axis between threaded ends 22 and 23, has mounted on its exterior surface a proximity switch 25, for example, a reed switch, having an electrical conductor 20 leading therefrom to the controller panel 21.

A valve 30 is located within the valve housing 24 and has an elongated cylindrical body portion 31 and a frusto-conical sealing section 32 at its lower end adapted to engage a frustoconical valve seat 33 in the lower portion of the valve housing 24. Although the valve 30 could be fabricated in various ways, it should be appreciated that it can be constructed in accordance with my co-pending U.S. Pat. application Ser. No. 301,557, filed on Oct. 22, 1972, for "Dual Sealing Element Valve for Oil Well Pumps and Method of Making Same," assigned to the assignee of the present invention. The full disclosure of said application is incorporated herein by reference.

A magnet 35 is attached to the uppermost section of the valve body 31 and is adapted to close the proximity switch 25 whenever the valve is lifted from the valve seat 33. A non-magnetic spring 36 is used between the upper end of the housing 24 and the valve 30 to spring load the valve 30 into its seating arrangement with the valve seat 33. It should be appreciated that although the housing 24 is illustrated as being of a plastic material, other non-magnetic housings can be used, for example, certain series of the stainless steel family.

The lower section of the cylindrical valve housing 24 above the valve seat 33 is enlarged with respect to the upper section of the valve housing 24, thus forming a chamber 37 for movement of the sealing member 32 as it rises from the valve seat 33. The periphery of such enlarged section has two or more openings 38 and 39 to allow fluid to pass therethrough.

In the operation of the system described with respect to FIGS. 1 and 2, it should be appreciated that as the fluid is pumped from the well 10, it enters the flow pipe 12 and is pumped through the valve assembly 19. In reference especially to FIG. 2, the flow is from the threaded end 22 towards the threaded end 23. Each time the subsurface pump (not shown) causes a surge of fluid, the valve 30 is lifted off the valve seat 33 and the fluid passes out through the ports 38 and 39 and on to the threaded end 23 and out through the flow pipe 12. As the valve 30 is lifted off the valve seat 33, the magnet 35 travels near the proximity switch 25, thereby closing the switch and allowing the conductor 20 to be grounded.

Referring now to FIG. 3, there is illustrated in greater detail the control panel 21. The conductor 20, which is grounded each time the proximity switch 25 of FIG. 2 is closed, is connected into an integrator timer 40, the output of the integrator timer 40 being connected to a shutdown timer 41 whose output is connected to a pump-up timer 42. The output of the integrator timer 40 is also connected to the variable electronic scaler 45 whose output drives a visual monitor 46 bearing the legend "EQUIPMENT MONITOR." The output of the pump-up timer 42, through a reset line 43, causes each of the three timers to be reset upon a recycling of the system. It should be appreciated that the illustration of FIG. 3 is included primarily to show the physical layout of the timing mechanisms and the visual monitor 46. As will be explained in more detail with respect to FIG. 4, the visual monitor 46 has any given number of lights but the preferred number is three, bearing the numerals "1," " 2" and "3," respectively. As the signals are received sequentially by the scaler 45 from the integrator timer circuit 40, the lights in the monitor 46 are activated in succession to indicate the number of times the system has been shut down. For example, during the operation of the system, the first time the system is shut down, the number "1" will be lighted by a red light on the monitor 46 and the numerals "2" and "3" will be sequentially illuminated on subsequent shutdowns. A recorder connection 47 is provided for utilizing a strip chart recorder or the like in providing a permanent monitor of the operation of the system.

The integration timer 40, shutdown timer 41 and pump-up timer 42 are commercially available from the Eagle Bliss Division of Gulf-Western Industries, Inc. of 925 Lake Street, Baraboo, Wisconsin 53193, such items bearing the following part numbers: integration timer 40, Part No. HP51A6; shutdown timer 41, Part No. HP510A6; and pump-up timer 42, Part No. HP56A6.

Referring now to FIG. 4, the electrical circuitry of the system is illustrated in greater detail. The proximity switch 25 is shown as applying, upon its closure, a ground to the conductor 20. The conductor 20 is connected to one of the outputs of the oscillator 50 within the integrator timer circuit 40. The oscillator 50 can be set at any frequency desired, but as is explained hereafter, is preferably operating at approximately twice the frequency of the variable frequency oscillator 51. By way of further example, the oscillator 50 has a nominal frequency of 10 kHz and the variable frequency oscillator 51 is set at 5 kHz. The outputs of the oscillator 50 and the oscillator 51 are connected to digital counters 52 and 53, respectively. The outputs of the counters 52 and 53 are connected into a comparator circuit 54. If the output of the counter 53 exceeds the output of the counter 52, as shown by the comparator 54, this is indicative that the system is pumping oil less than 50 percent of the time. In response to such an adverse comparison, the comparator 54 generates a signal which in turn triggers the single shot multivibrator circuit 55 which in turn is connected into other of the components of the circuitry of FIG. 4. Although the oscillator 50 has been described as being set at twice the frequency of the oscillator 51, other frequencies can be used to provide different percentages. Thus, if the oscillator 50 is set at four times the frequency of the oscillator 51, then the system ascertains whether the oil is being pumped 25 percent of the time. It should also be appreciated that it is preferable to provide a comparison over a given period of time, for example, during one minute. This eliminates problems such as might be occasioned by an infrequent gas bubble or the like which might cause the valve to not come off the seat 33 upon any given stroke of the pump. Since a percentage of 50 percent is theoretically the perfect condition, a reasonable setting of the variable frequency oscillator would be 4 kHz in conjunction with the 10 kHz output of the oscillator 50. Under these conditions, a signal would not be produced from the single shot multivibrator 55 until there was a showing that the system was operating less than 40 percent of the time.

The output of the single shot multivibrator 55 is connected by conductor 60 to the input of the shutdown timer 41 which can be adjusted to any predetermined period, for example, four hours. The output of the shutdown timer 41 is connected to the input of a pump-up timer 42 which can also be adjusted to any preselected time, for example, 20 minutes. The shutdown timer 41 and the pump-up timer 42 each contains a single shot multivibrator for producing a single pulse at their respective outputs at the conclusion of the given time periods.

The conductor 60 is also connected to the coil 63 of a relay 64, the other side of the coil 63 being grounded. The relay 64 has a pair of normally open and normally closed contacts. The output of the shutdown timer is also connected to the coil 65 of a relay 66, the other side of the coil 65 being grounded. The relay 66 also has a pair of normally open and normally closed contacts. The output of the pump-up timer 42 is connected to the coil 67 of a relay 68, the other side of the coil 67 being grounded. The relay 68 also has a pair of normally open and normally closed contacts.

The lower normally open contact of relay 64 is connected to a power supply, illustrated as being a battery 70 which is of adequate voltage to maintain the relay 64 in the latched position. The lower normally open contact of relay 66 is similarly connected to a power supply 71 for similar reasons. The upper normally closed contact of relay 64 is connected to a conductor 72 which in turn is connected to the upper normally open contact of relay 66. The upper wiper arm of relay 64 is connected to conductor 73 which is connected directly to the prime-mover power supply 74 output. The conductor 73 is also connected to the upper wiper arm of relay 66. The lower wiper arm of relay 64 is connected to the upper wiper arm of relay 68. The lower wiper arm of relay 66 is connected to the lower wiper arm of relay 68. The ungrounded side of the coil 65 in relay 66 is connected to the lower normally closed contact of relay 68. The upper normally closed contact of relay 68 is connected to the ungrounded side of the coil 63 in relay 64.

The output of the single shot multivibrator 55 is also connected through conductor 80 to the input of a variable electronic scaler 45 which, for example, produces one pulse out for each three pulses in from the single shot multivibrator 55. The output of the scaler 45 is connected to the top of a coil 82 of a relay 83, the other side of the coil 82 being grounded. The upper normally closed contact of relay 83 is connected directly to the prime-mover 17. The upper wiper arm of relay 83 is connected to conductor 72. The lower wiper arm of relay 83 is connected to a power supply 84 suitable for latching the relay 83. The lower normally open contact of relay 83 is connected through a springloaded normally closed switch 85 back to the ungrounded side of the coil 82 of relay 83.

In the operation of the circuit of FIG. 4, there has already been described the effect of an adverse comparison being made in the circuit 54 to thus produce a single voltage pulse from the output of the single shot multivibrator 55 which occurs on the conductors 60 and 80. Such a pulse appearing on the input of the shutdown timer 41 causes the timer 41 to count for a predetermined time interval, for example, 4 hours. Simultaneously with the production of this signal upon conductor 60, the relay 64 is momentarily energized and latched into a position such that the wiper arms are in contact with the normally open contacts, respectively. The action of the power supply 70 causes the relays to be latched in such a position. This removes the prime-mover power supply 74 from the prime-mover 17 and the pumping action terminates. As soon as the preselected time of the shutdown timer 41 has expired, a single pulse is generated at the output of the timer 41 which activates the relay 66. This causes the relay 66 to latch in position such that the wiper arms are in contact with the normally open contacts, respectively. This causes the output of the prime-mover power supply 74 to be connected to the prime-mover 17 and the pumping action is again commenced. Simultaneously with the activation of the relay 66, the output of the timer 41 is coupled into the pump-up timer 42 which is set for a predetermined time, for example, 20 minutes, and thereafter which generates a single pulse of its own which is coupled back to reset the pump-up timer 42, the shutdown timer 41 and the counters 52 and 53 in the integration timer 40. Simultaneously with this resetting operation, the output of the pump-up timer 42 activates the relay 68 which causes the relays 64 and 66 to be unlatched and their wiper arms to be returned to the positions as illustrated in FIG. 4. This allows the output of the prime-mover power supply 74 to remain connected to the prime-mover 17 and the system has thus been recycled.

Each time the output of the single shot multivibrator 55 produces a voltage pulse on the conductor 80, the pulse is coupled into the variable scaler 45 which is set, by way of example, to produce a single output pulse for each three pulses in. After the system has been shut down three times, three pulses will have been produced by the single shot multivibrator 55 and thus the scaler circuit 45 will produce a single pulse at its output which activates the relay 83 and which is latched in such a position by the power supply 84. This causes the prime-mover power supply 74 to be removed from the prime-mover 17 and the pumping action is terminated. The system cannot be recycled at this point until the spring-loaded switch 85 is manually activated to the open position to unlatch the relay 83 and thus allow the system to be recycled.

An additional feature may be added to the above system by the use of the motor valve 86 of FIG. 5 to replace valve assembly 19 in pipe 12.

Referring to FIG. 5, the flowline 12 communicating with the production tubing in the wellbore receives fluid produced as a result of the pumping done by reciprocation of the pump sucker rod 11 located concentrically in the tubing.

A gas-pressure actuated motor valve 86 is interconnected into flow pipe 12 and receives actuation pressure signals through piping 87 which communicates with gas pressure in the annulus between the borehole and the tubing. Motor valve 86 is a commercially available unit such as the type D motor valve sold by Guiberson Division of Dresser Industries, Dallas, Texas, under the part number 53339. The valve has a ported partition 88 with the port 96 having a valve seating surface thereon. A valve element 89 is suspended from a valve rod 90 and arranged to seat in the valve seat. The rod extends upward through a housing 91 and is joined to a diaphragm 92 in a pressure chamber 93. A pressure inlet 94 is located atop the pressure chamber 93 and an electric solenoid valve 95 is connected into the inlet 94 to control gas flow into the pressure chamber.

A differential pressure switch 97 is arranged to measure and control the differential pressure across the motor valve by receiving pressure signals through piping 98 and 99, which piping transmits pressurized fluid to switch 97 from upstream and downstream of the motor valve.

The differential pressure across valve 86 is determined by switch 97 and an electrical signal is transmitted down electrical conduit 100 to the solenoid valve 95 to control actuating pressure on diaphragm 92. Switch 97 can be adjusted to maintain any desired pressure differential across motor valve 86 ranging from about one PSI upward. When the pressure differential drops below a preset valve and switch 97 is unable to raise the differential by control of the motor valve, this indicates that the well is no longer flowing and an electrical signal is then transmitted to conduit 20 which leads to the controller panel.

Operation of the system after generation of the signal along conduit 20 proceeds as previously described in conjunction with valve 19. FIG. 6 illustrates an alternative sensing device which may be used in place of the motor valve 86. In FIG. 6, a flat orifice plate 101 is interposed in the production flow pipe 12. The flow pipe is provided with two abutting flanged ends 102 and 103 which are flanged up in clamping relationship about the orifice plate 101. This plate has a restricted circular flow orifice located generally in the center of flow pipe 12, which orifice has a flow area substantially smaller than the cross-sectional area of the flow pipe.

A pressure tap 98 is made upstream of the orifice plate and a tap 99 is made downstream. Pressure conduits 98 and 99 are connected to a pressure differential switch 104 which monitors the differential pressure across the orifice 101. When the differential pressure across the orifice drops below a preselected level, the switch 104 sends an electrical signal down conduit 20 to the controller panel and the well monitoring system proceeds to operate identically to the operation described in conjunction with valve 19.

A third sensing system is disclosed in FIG. 7 in which a spring biased flow valve 105 is shown interconnected into flow pipe 12 to measure and control the flow of produced fluids from the well. Valve 105 comprises a housing 106 having a ported partition 107 therein. Partition 107 has a port opening 108 therethrough with an integral valve seat around the port. A valve element 109 is arranged on a valve stem 110 to reciprocate up and down into and out of sealing engagement with the seating area of port 108. Stem 110 extends upward out of housing 106 into an upper housing cover 111. Stem 110 has an outwardly extending spring abutment plate 112 attached thereto upon which is compressively held a coil spring 113. Coil spring 113 also abuts the upper end of cover 111 and, being in compression, tends to continuously urge valve element 109 into engagement with port opening 108. Valve element 109 is opened by the pressure of fluids flowing in pipe 12 which fluid pressure acts upward on valve element 109 to overcome the spring bias and maintain the element in an elevated position off of port 108. Likewise, a similar operation of motor valve 86 is achieved when the flow pipe pressure acting on the bottom of valve element 89 is sufficient to overcome the constant annulus gas pressure acting downward on diaphragm 92. Also, solenoid valve 95 can be preset so that when a certain desired pressure differential is achieved, a signal switch 97 causes solenoid valve 95 to exhaust the annulus gas pressure acting on diaphragm 92 allowing the valve 89 to fully open.

Pressure conduits 98 and 99 tap the pressure upstream and downstream of valve 105 and transmit the fluid pressure to differential pressure switch 104. As previously described, switch 104 transmits an electrical signal to the controller panel and the system operates as described in conjunction with valve 19.

Thus it should be appreciated that there have been described and illustrated herein the preferred embodiments of the present invention wherein a vastly new and improved system has been provided for making a determination as to the percentage of time in which fluid is being produced from an oil well, and to control the pumping operation based upon such determination. Those skilled in the art will recognize that modifications can be made to these embodiments as illustrated and described. For example, other types of valves and sensing mechanisms can be used to create an event indicative of the flow of oil through the flow line. By way of a specific example, the use of a float valve well known in the art can be used to generate an electrical signal or some other such event and such use is contemplated by the invention hereof. Such an event can then be used to aid in the determination of the percentage of time in which the oil is flowing through the flow line. Likewise, while the preferred embodiment contemplates the use of various electrical, mechanical and electro-mechanical timing mechanisms, as well as the use of solid state devices such as the scaler circuit 45, those skilled in the art will recognize that equivalent devices can be used to provide the results of the invention. For example, the entire circuitry of FIG. 4 can be fabricated from solid state components to provide greater space saving and cost reduction, as well as vastly improved reliability. Furthermore, although the preferred embodiment of the invention contemplates the use of electrical signals in determining the percentage of time in which the oil is flowing through the flow pipe, those skilled in the art will recognize that pneumatic signals can also be used in making such a determination. Likewise, although not illustrated, a ramp voltage device can be used and its amplitude compared at a given time with a known amplitude to provide a determination of the percentage of time during which the oil is being pumped.

In addition to these alternatives, it is clear that other means may be used to sense pressure differential across a flow restriction in the flowpipe. For instance, where flow conduits are depicted in FIGS. 5-7 to transmit the actual fluid under pressure to a differential pressure switch, the flow conduits could be replaced with one electronic pressure switch upstream and one downstream of the flow restriction, with the switches capable of sensing the pressure in the flowpipe at each of their locations and converting the pressures into electrical signals proportionate to the flowpipe pressure. These two electronic signals from upstream and downstream of the flow restriction would be transmitted via electrical conduits to an electrical comparator which would continuously compare the two electronic signals and determine from them the instantaneous differential pressure. Then a control signal would be generated and conveyed to the controller panel as previously described.

It also would be possible to utilize motor valves of different types than that disclosed; for instance an electric-motor-operated motor valve could be used instead of the air pressure operated type described. Additional types of actuation mechanisms could also be utilized. Thus, the invention is declared to cover all changes and modifications of the specific examples of the invention herein disclosed for purposes of illustration which do not constitute departures from the spirit and scope of the invention.

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