THE SYSTEM AND METHOD

(Docket No.l053a) Inventors:

Craig Lamascus

and

Lloyd Wentworth Small Entity This international application is being filed with the United States Patent and

Trademark Office as the receiving office. C/O John J. Connors

Patent Attorney

CUSTOMER NUMBER 021905

Connors & Associates, pc

13421 Danbury Lane, Unit 134i

Seal Beach, California, 90740, USA

949-833-3622 (Phone)

562-431-5881 (Fax)

email: john@connorspatentlaw.com RELATED PATENT APPLICATION & INCORPORATION BY REFERENCE This international patent application claims the benefit under 35 USC 119(e) of U. S. Provisional Patent Application No.61/809,823, entitled "PARTIAL STROKE CONTROL SYSTEM AND METHOD FOR LOW ROD TENSION IN OIL/GAS WELLS," filed April 8, 2013. This related application is incorporated herein by reference and made a part of this application. If any conflict arises between the disclosure of the invention in this international application and that in the related provisional application, the disclosure in this international application shall govern. Moreover, any and all U. S. patents, U. S. patent applications, and other documents, hard copy or electronic, cited or referred to in this application are incorporated herein by reference and made a part of this application. DEFINITIONS The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.

The words "oil well" include natural gas wells, and oil and gas wells including those that produce water or other fluids. BACKGROUND Pumping units and rods used on oil wells typically have a fixed stroke length measured in inches of surface travel up and down. The surface stroke length of the pumping unit is a function of the geometry and mechanical configuration of the pumping unit. The surface stroke length of the rod, under normal operating conditions, is identical to that of the pumping unit. Under normal conditions, as the crank or drive chain of the pumping unit moves through a single revolution, the rod, which is operably connected to the pumping unit, makes one complete upstroke and downstroke in unison with the pumping unit. There are, however, conditions, usually temporary, that prevent the rod from making a complete stroke in unison with the pumping unit. Such a condition is called "float" or "rod float" wherein the rod and the pumping unit become mechanically disconnected.

The mechanical design of a pumping unit uses a prime-mover, usually in the form of an AC motor, turning in one direction. The AC motor is connected to a series of power transmission devices that are comprised of belts, pulleys, sprockets, gear-boxes and/or drive chains. The mechanical design of the pumping unit reverses the direction of rod motion from up to down at the top of the rod stroke and from down to up at the bottom of the rod stroke. Under normal conditions the direction of the motor rotation does not change while in operation. Under normal conditions, as the crank or drive chain of the pumping unit moves through a single revolution, the rod is operably connected to the pumping unit to make one complete up and downstroke in unison with the pumping unit. However, there are conditions, usually temporary, that may prevent the rod and pump from making a complete stroke in unison with the pumping unit. These conditions are characterized by extremely low or zero tension in the rod. This is sometimes called float, rod float, or zero tension condition, and is a condition or circumstance wherein the pumping unit becomes disconnected from the rod because the pumping unit moves further down on the down stroke than the rod does. If this occurs, the rod and pump are no longer operably connected to the pumping unit for some portion of the downstroke. This condition is usually temporary. One circumstance that may result in float is extremely high viscosity oil. Another circumstance that may result in float is a pump that is bound up, or stuck, so that the pump and rod do not move down as quickly as the pumping unit moves down. Our partial stroke control method uses bi-directional motion of the crank or drive chain to cause the rod to move only through some portion of its normal surface stroke. This is useful because partial stroke of the rod and resulting partial stroke of the pump may be useful in eliminating or mitigating the cause of the problem that is causing the low-tension condition. The prior art pumping system only reverse the direction of the movement of the rod through mechanical means, not by reversing the rotational direction of the electric motor driving the pumping system as we do.

On a "walking beam" pump the connection between the rod and the pumping unit is done with a carrier bar and a bridle assembly connected to a horsehead. The bridle is made of cable. The carrier bar and bridle configuration allows the pumping unit to exert force to pull the rod up or prevent it from falling. A rod clamp does not allow the rod to fall past the point at which the rod clamp engages the carrier bar. This typical configuration does not allow the pumping unit to exert force to push the rod down. In the event that the pumping unit moves down at a faster rate than the rod falls into the well, then rod float occurs. When rod float occurs, tension in the rod dramatically decreases and the bridle assembly goes into a "slack" condition. The carrier bar can move down on the rod.

The connection between the rod and the pumping unit can vary depending on the type of pumping unit being used. For example, ROTAFLEX® pumping units use a belt instead of a horsehead. The bridle consists of metal bars. The carrier bar and bridle configuration allow the pumping unit to exert force to pull the rod up or prevent it from falling. The rod clamp does not allow the rod to fall past the point at which the rod clamp engages the carrier bar. The typical configuration does not allow the pumping unit to exert force to push the rod down. In the event that the pumping unit moves down at a faster rate than the rod falls into the well, then rod float occurs. When rod float occurs, the rod tension decreases and the bridle assembly goes into a "slack" condition, and the carrier bar can separate from the rod. SUMMARY Our control system, oil well and method have one or more of the features depicted in the embodiment discussed in the section entitled "DETAILED DESCRIPTION OF SOME ILLUSTRATIVE EMBODIMENTS." The claims that follow define our control system, oil well and method, distinguishing them from the prior art; however, without limiting the scope of our control system, oil well and method as expressed by these claims, in general terms, some, but not necessarily all, of their features are:

One, our system prevents a rod of a pumping unit for an oil well from completing a downstroke upon detecting a condition indicating that rod float is about to begin, specifically a decrease in tension. Our system includes an AC electric motor that operates in a one direction to drive the rod through an upstroke and the downstroke, a sensor that detects tension in the rod on the downstroke of the rod and provides a measured tension signal corresponding to the tension, and a control circuit. The control circuit is responsive to the measured tension signal to reverse the motor's forward direction whenever the tension signal is below a predetermined low-tension setpoint.

Two, the circuit includes a microprocessor that receives from the sensor the measured tension signal and compares the measured tension signal to the predetermined low-tension setpoint. The microprocessor generates a change direction command signal upon determining that the measured tension signal is below the low-tension setpoint to reverse the motor's direction, preventing the rod from completing the stroke cycle.

Three, the change direction command signal is always generated on the downstroke, causing the rod to begin moving in an upward direction increasing tension in the rod. The reversal of direction of the motor continues with each downstroke as long as a change direction command signal is generated on the downstroke, resulting in a series of repeated interruptions of the complete stroke cycle.

Four, a well manager, in response to a determination that the measured tension signal is below a minimum load shutdown setpoint, generates a shutdown command signal used to disabled the operation of the pumping unit. In other words, if the measured rod tension drops below a predetermined threshold, the pumping unit is shutdown. The low-tension setpoint is set at a value higher than the minimum load shutdown setpoint established by the well manager.

Our oil well employs our system and is operated according to our methods which include: (i) A method of operating an oil well comprising the steps of

(a) measuring the tension in a rod of a pumping unit for the oil well operably connected to an AC electric motor that operates in one direction to drive the rod through a complete stroke cycle comprising an upstroke and a downstroke,

(b) comparing said measured tension to a predetermined low-tension setpoint to determine if said measured tension signal is below said low-tension setpoint,

(c) reversing the direction of the motor when the measured tension signal is below said low-tension setpoint so that the rod does not complete its stroke cycle. (ii) A method of operating an oil well encountering down hole obstructions causing a rod to disconnect from the rod's drive mechanism to produce rod float, said method comprising the steps of

(a) operating a motor that normally drives the rod to move in one direction through a downstroke and an upstroke,

(b) detecting on the downstroke the a condition indicating that rod float is about to begin,

(c) reversing the direction of the motor upon detecting said condition so that the rod does not complete the stroke cycle, and

(d) continuing to reverse the direction of the motor with each downstroke as long as said condition is detected, resulting in a series of repeated interruptions of the complete stroke cycle. These features are not listed in any rank order nor is this list intended to be exhaustive. DESCRIPTION OF THE DRAWING Embodiments of our system and method are discussed in detail in connection with the accompanying drawing, which is for illustrative purposes only. This drawing includes the following Figures, with like numerals indicating like parts:

Figure 1 A is an illustration comparing a pumping unit rod's position without rod float and with rod float.

Figure 1 is a schematic diagram of a pumping unit for an oil well that uses our control system depicted in Figure 2. Figure 2 is a schematic diagram of our control system for an oil well.

Figure 3 is a schematic illustration of an oil well employing a walking beam pumping unit assembly using our system.

Figure 3A is a fragmentary view of a portion of the walking beam pumping unit assembly showing a rod with a load cell used to sense tension in the rod mounted on the rod.

Figure 3B is a cross-sectional view taken along line 3B-3B in Figure 3A.

Figure 4 is a schematic illustration of an oil well employing a ROTAFLEX® pumping unit assembly using our system.

Figure 4A is a fragmentary view of a portion of the ROTAFLEX® pumping unit assembly showing the location of its rod with a load cell used to sense tension in the rod mounted on the rod. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS General Our system and method of operating an oil well prevents rod float. It achieves this by monitoring tension in the rod. Upon encountering a condition that will cause rod float tension in the rod decrease. By detecting a decrease in rod tension, and reversing the direction of the pumping unit's motor to change direction of the pumping unit from down to up at some point during its downward motion, rod float is avoided. Rod float is depicted in Figure 1A, which shows a ROTAFLEX® pumping unit 100 on the downstroke in position I without rod float and in position II with rod float where the rod R has separated from a bridle 102 of the pumping unit 100. When rod float occurs, tension in the rod R decreases. In most pumping units operation at extremely a low, or zero, rod tension will result in mechanical damage to the pumping unit or rod. In our system each time rod tension falls below a predetermined value on the downstroke, the rod R changes direction from down to up.

As best illustrated in Figures 3A and 4A, our method monitors tension in the rod R as measured by means of a load cell LC that is connected to a portion of the rod R. Upon encountering downhole conditions normally causing a rod to disconnect from rod's drive mechanism to produce rod float, the load cell detects a decrease in tension in the rod that occurs when such a condition persists. In other words, upon detecting the onset of rod float on the rod's downstroke, the direction of rotation of the pumping unit's motor is reversed. With each downstroke, the motor's direction of rotation is reversed as long as the condition that will cause rod float persists. Upon detecting a decrease in rod tension, the load cell LC generates a signal that causes the pumping unit's motor M to reverse direction, so that the rod R does not complete the stroke cycle. This reversed direction of movement of the motor M continues as long as rod tension does not fall below a predetermined level. The reversal of motor's rotational direction with each downstroke is continued as long a tension condition exists indicating that rod float is about to begin, resulting in a series of repeated interruptions of the complete stroke cycle. To complete the stroke cycle in some oil wells their motors must be set to operate in only a forward direction to move through a complete stroke cycle. In such oil wells, for example, the Mark II walking beam unit, it is necessary to operate in only the forward direction after freeing the oil well of the conditions causing rod float. In such cases, our system's control circuit CC (Figure 2) includes a microprocessor 10a (Figure 1) designed to reset the pumping unit's motor for operation in the forward direction upon return to normal operations with the well unplugged.

A well manager unit WM, in response to a determination that a measured tension signal is below a minimum load shutdown setpoint, generates a shutdown command signal used to disabled the operation of the pumping unit UM. The low-tension setpoint is set at a value higher than a minimum load shutdown setpoint established by the well manager unit. Illustrative Embodiments Our system generally designated by the numeral 10 in Figure 1 controls the operation of an oil well (Figures 3 and 4) in a manner that eliminates or mitigates a problem with the well associated with low-tension "rod float." Our control system 10 controls the operation of the well in a predetermined manner to reverse the movement of the motor M and rod R during a downstroke when a tension condition is detected indicating that rod float is about to begin. The tension is measured by means of a load cell S2 that is connected to a rod R of a pumping unit PU shown in Figures 1 , 3 A and 4A. The load cell LC rests on an inside surface of a carrier bar CB attached to a bottom of a bridle wall of the pumping unit PU, and a rod clamp RC presses the load cell against the inside surface of the carrier bar. The rod R extends through the carrier bar CB. When well conditions are such that rod float is about to begin, tension in the rod R decreases.

Our control system designated by the numeral 10 controls the operation of the pumping unit PU of the oil well using a variable frequency AC drive VFD (Figure 1) to control the operation of an AC motor M driving the pumping unit PU. Any variable frequency drive VFD may be used in our system. This drive VFD may have dynamic braking, regenerative braking, or no braking at all. Regenerative braking is disclosed in United States Patent Application No. 12/605,882, filed October 26, 2009, which uses a conventional apparatus, for example, sold by ABB OY DRIVES of Helsinki, Finland, under the designation ACS800-U11-0120-5.

The variable frequency drive VFD is operatively connected to the AC motor M. A microprocessor 10a is used to control the operation of the variable frequency drive. The microprocessor 10a may be a component of the variable frequency drive VFD, or it can be a separate programmable device, such as a PLC or an embedded computer. The number of strokes per minute (SPM) of the pumping unit PU is increased or decreased as determined by a conventional well manager unit WM, for example, sold by Lufkin Automation of Houston, Texas, USA, under the designation SAM™ Well Manager. The pumping unit PU may be, for example, a walking beam pumping unit as shown in Figures 3, 3 A and 3B or a ROTAFLEX® pumping unit assembly as illustrated in Figures 4 and 4 A. In both pumping units the rod R extends below ground level into the well formation. The AC electric motor M has a drive shaft 12 operatively connected to a gearbox GB having its drive shaft 16 operating a drive mechanism of the pumping unit PU to pump oil from the well. The pumping unit PU cycles through one entire stroke as determined by the ratio of the gears in the gearbox GB and motor revolutions.

There is a sensor SI that functions as a location detector. The sensor SI detects when the rod R is at a predetermined position in the stroke cycle and provides a signal each time the rod is at this predetermined position, for example, at the end of the downstroke and provides a signal (herein the "end of stroke" signal). This "end of stroke" signal is sent to an input 23 of a well manager unit WM and an input 24 of the microprocessor 10a of the AC regenerative drive unit RDU. The sensor S2 may be a load cell that detects the tension in the rod R and sends a signal (herein "tension" signal) to an input 25 of the well manager unit WM and to an input 22 of the microprocessor 10a of the variable frequency drive VFD.

The well manager control unit WM is used to monitor and control well parameters. For example, when the pump chamber 18 is completely filled, or the amount of fill is above the fill set point, the well manager unit WM, which is in communication with the microprocessor 10a, sends a signal (herein "speed" signal) to the variable frequency drive VFD to increase the motor's average speed (rpm's), or maintain the motors average speed in the case when the motor is already operating at its maximum average speed. And, when the pump chamber 18 is only partially filled (less than 25%), the "speed" signal sent to the variable frequency drive VFD indicates a decrease in the motor's average speed (rpm's). Ideally, the "speed" signal corresponds to an optimum average motor speed to maximize oil production under the then present well conditions. The "end of stroke" signal indicates that the rod R is in a predetermined position that is the same for each stroke cycle.

For each stroke cycle the well manager control unit WM designates the speed of the motor M. The well manager unit WM may, with each cycle, change the "speed" signal to either increase or decrease the average motor speed or maintain the average speed as previously established. The microprocessor 10a is programmed to respond to the "speed" signal from the well manager unit WM. During each stroke cycle, the variable frequency drive VFD converts input AC current from the AC power grid PG that is at a standard frequency and voltage to a variable AC current having different frequencies and voltages as established by the well manager unit WM. The variable frequency drive VFD by applying a variable AC current to the motor M at an output 20 changes the motor speed. In our system and method, independent of the well manager unit WM, the microprocessor 10a is in control of reversing motor direction on the downstroke through the variable frequency drive VFD. The variable frequency drive VFD can operate normally with inter-stroke speed changing control, with speed control from the well manager WM, or with no speed control at all in normal operating mode.

In our control system 10 the measured tension is compared to a threshold tension called a "low-tension setpoint." In the event that the measured tension drops below the low - tension setpoint, a condition is created calling for a "Change Direction Command," or in other words a Change Direction Command condition exists. In our system and method, speed changes after reversing and then gradually restores the speed to normal if a Change Direction Command condition occurs. When this condition occurs a Change Direction Command signal is generated and the direction of the motor M, and the direction of the crank or drive chain motion, is reversed. In all cases in which our control system 10a is useful the Change Direction Command signal is generated on the downward stroke of the rod R and the pumping unit PU. Since the pumping unit PU and rod R were moving down prior to the Change Direction Command signal, reversing the direction of the motor M and subsequent direction of the crank or drive chain will always result in the pumping unit PU and rod R beginning to move up. Motion of the pumping unit PU and rod R in the up direction will result in an increase in measured tension. The change in direction of the pumping unit's motor M and rod R from moving down to moving up at some location in the downstroke results in a partial stroke, or a stroke that is only a portion of the normal surface stroke. If the Change Direction Command condition occurs during subsequent strokes, then our control system 10a will continue to partial stroke the well as long as the Change Direction Command condition continues to repeat. The Change Direction Command condition may occur only on starting. The Change Direction Command condition may occur during a normal run at high speed. The Change Direction Command condition may only happen during a single isolated stroke, or it may persist for thousands of strokes over a period of several days. The Change Direction Command condition may be intermittent or continuous. The Change Direction Command condition may occur at the same location in the downstroke or different locations in the downstroke.

For some pumping units, our control system 10a may employ a preferred forward direction. For such units, if the Change Direction Command condition results in "reverse" operation for a single stroke in which the Change Direction Command does not repeat, then the direction of the motor M and subsequent direction of the crank or drive chain is reversed to result in "forward" operation of the pumping unit PU.

Our control system 10a may be used in conjunction with a Minimum Load Shut Down function. The Minimum Load Shut Down function works in such a way that the pumping unit PU is completely disabled in the event the measured rod tension drops below a threshold. The Minimum Load Shut Down threshold is called "Min Tension Setpoint". If the measured rod tension drops below the Min Tension Setpoint, the pumping unit PU is disabled and must be reset. The Partial Stroke "Low Tension Setpoint" and "Min Tension Setpoint" are related in the following way: The "Low Tension Setpoint" must be set to a value higher than the "Min Tension Setpoint" if the Partial Stroke Control is be to effective in maintaining the pumping unit PU in an operating condition and preventing mechanical damage to the pumping unit and/or rod.

Our control system 10a allows pumping units installed on oil wells to be operated under conditions that would normally result in shutdown of the pumping unit PU and loss of production from the well, at least temporarily. The number of events in a given period of time that causes the Change Direction Command to be activated can be broadly considered to be an indicator of "pump obstruction." A large number of Change Direction Command conditions in a given period of time indicates more severe pump obstruction. A small, or zero, number of Change Direction Command conditions in a given period of time indicates a less or no pump obstruction. Monitoring the number of pump obstructions is a useful measure of pump and well condition. A large number of pump obstructions may indicate a need for pump servicing. Our control system 10a may be activated or de-activated, by means of a software switch, at the discretion of the operator.

Referring to Appendix A attached, the microprocessor 10a is programmed using the following variables: Reversal Setpoint Min, Reverse Enabled, Reverse Complete, Partial Counter, Reverse Command, Min Speed 2001, Speed Estimated 102, Filt Tension Scaled, Reversal Time Array, Reversal Time Array Counter and Return Forward. The variables are described as follows - Reversal Setpoint Min is a number that represents the minimum tension threshold that triggers a reversal of the drive mechanism. Reverse Enabled is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below. Reverse Complete is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below. Partial Counter is the name of a variable that contains an integer that used in the implementation of the control. Reverse Command is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below. Min Speed is the name of a variable that contains an integer that represents the setting of the minimum motor speed in units of RPM. Speed Estimated is the name of a variable that contains an integer that represents the estimated motor speed in units of RPM. Filt Tension Scaled is the name of a variable that contains a real number that represents the filtered and measured tension from the load cell. Return Forward is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below. Reverse Enabled and Reverse Complete are both set to TRUE at the beginning of the control operation. The Filt Tension Scaled is compared to the Reversal Setpoint Min and whenever the Filt Tension Scaled drops below the Reversal Setpoint Min and Reverse Enabled is set to TRUE then Reverse Enabled is set to FALSE and Reverse Complete is set to FALSE and the Partial Counter variable is incremented up by a value of 1. Partial Counter is represented internally as an integer. If bit 0 of the Partial Counter integer is high then Reverse Command is set to TRUE and if Min Speed 2001 is not already a negative number it is set to a negative number. If bit 0 of the Partial Counter integer is low then the Reverse Command is set to FALSE and if Min Speed 2001 is not already a positive number it is set to a positive number. If the Reverse Command is TRUE and the Speed Estimated drops below Min Speed 2001 times 1.1 and Filt Tension Scaled is not lower than Reversal Setpoint Min times 1.1, then Reverse Enabled is set to TRUE. If Reverse Command is FALSE and Speed Estimated 102 is greater than Min Speed 2001 times 0.9 and Filt Tension Scaled is greater than Reversal Setpoint Min times 1.1 then Reverse Enabled is set to TRUE as well. If Reverse Command is FALSE and Speed Estimated 102 bit 15 is FALSE (only happens when motor speed is positive, indicating forward rotation) then Reverse Complete is set to TRUE. If Reverse Command is TRUE or ^" Speed Estimated 102 bit 15 is TRUE (only happens when motor speed is negative, indicating reverse rotation) then Reverse Complete is set to FALSE. If Reverse Command is TRUE and the End of Stroke signal is detected then the Partial Counter is incremented by 1, thereby returning the pumping unit to the preferred "forward" direction of operation of the drive mechanism. In all cases in which our method is useful the Reverse Command will occur on the downward stroke of the rod and the pumping unit. Since the pumping unit and rod were moving down prior to the Reverse Command, reversing the direction of the motor and subsequent direction of the crank or drive chain will always result in the pumping unit and rod beginning to move up. Motion of the pumping unit and rod in the up direction will always result in an increase in measured tension.

When Partial Stroke Control is active and the Reverse Command variable goes from FALSE to TRUE, the change in direction of the pumping unit and rod from moving down to moving up at some location in the downstroke results in a partial stroke, or a stroke that is only a portion of the normal surface stroke. If the Reverse Command variable makes any subsequent transitions from FALSE to TRUE then the Partial Stroke Control will continue to partial stroke the well as long as the Reverse Command continues to transition from FALSE to TRUE. The Reverse Command may transition from FALSE to TRUE only on starting. The Reverse Command may transition from FALSE to TRUE during a normal running condition at high speed. The Reverse Command may transition from FALSE to TRUE during single isolated stroke or it may persist for thousands of strokes over a period of several days. There will be no damage to the pumping unit if this condition does persist. The Reverse Command transition from FALSE to TRUE may be intermittent or continuous. The Reverse Command transition from FALSE to TRUE may occur at the same location in the downstroke or different locations in the downstroke. Our method defines a preferred forward direction. If the Change Direction Command condition results in "reverse" operation for a single stroke in which the Change Direction Command does not repeat, then the direction of the motor and subsequent direction of the crank or drive chain is reversed to result in "forward" operation of the pumping unit, as is explained above.

Our method may be used in conjunction with a Minimum Load Shut Down function. The Minimum Load Shut Down function works in such a way that the pumping unit is completely disabled in the event the measured rod tension drops below a threshold. The Minimum Load Shut Down threshold is called "Min Tension Setpoint". If the measured rod tension drops below the Min Tension Setpoint, the pumping unit is disabled and must be reset. In most pumping units operation at extremely low or zero measured rod tension will result in mechanical damage to the pumping unit or rod. The Partial Stroke Reversal Setpoint Min and "Min Tension Setpoint" are related as follows: The Reversal Setpoint Min must be set to a value higher than the "Min Tension Setpoint" if the Partial Stroke Control is be to effective in maintaining the pumping unit in an operating condition and preventing shutdown or mechanical damage to the pumping unit and/or rod.

Our method allows pumping units installed on oil wells to be operated under conditions that would normally result in shutdown of the pumping unit or damage to the pumping unit or rod. Either shutdown or damage causes loss of production from the well. The number of events in a given period of time that cause the Reverse Command to make a transition from FALSE to TRUE can be broadly considered to be an indicator of "pump obstruction". The number of pump obstructions that occur in a given amount of time is called the Reversal Time Array Counter. The Reversal Time Array Counter is a variable that contains an integer that represents the number of pump obstruction events in the previous 24 hour period. A large value of the Reversal Time Array Counter indicates more severe pump obstruction. A small, or zero, value of the Reversal Time Array Counter indicates a less or no pump obstruction.

Reversal Time Array is the name of a variable that is an array comprised of 500 elements of a time variable. The time variable is comprised of two 32 bit words, a Hi Word and a Low Word, which are used to represent time as a UTC (English: Coordinated Universal Time) variable. AOl is the name of a variable that contains an integer that is used to control the signal level of an analog output. Seconds Prior is the name of a variable that contains real number that is used to represent the amount of time between present time and when a Reverse Command event occurred. Index_3 is the name of a variable that contains an integer that is used to index a control loop in the logic. The conversion logic begins with a routine that is activated whenever a Reverse Command event occurs. This control routine goes through the entire Reversal Time Array by setting Index_3 to a value of 498 and then decrementing it by a value of 1 until it reaches a value of 0. At each value of Index_3 the array element of Reversal Time Array location Index_3 plus 1 is given the value located in the array element of Reversal Time Array location Index_3. This has the effect of shifting all of the array elements backwards in the Reversal Time Array by one location at each occurrence of a Reverse Command event. Then the Reversal Time Array at location 0 is given the value of the present time. Every 60 seconds another control routine is activated that counts the number elements in the Reversal Time Array that are not equal to zero. During this routine any elements in the Reversal Time Array that are found to be older than 86,400 seconds are set to a value of zero. The Reversal Time Array Counter is set to the number of non-zero elements found in the array. Then the Reversal Time Array Counter is scaled to give an analog output that represents the number of Reverse Command events in the preceding 24 hour period. It is the concept of monitoring the number of stuck pump occurrences in some defined period of time that is represented in the Reversal Time Array Counter and this is what is valuable to monitor. Partial Stroke Control may be activated or de-activated, by means of a software switch, at the discretion of the operator. SCOPE OF THE INVENTION The above presents a description of the best mode we contemplate of carrying out our method and control system for operating an oil well and a well using our control system, and of the manner and process of making and using them, in such full, clear, concise, and exact terms as to enable a person skilled in the art to make and use. Our method and control system for operating an oil well and a well using our control device are, however, susceptible to modifications and alternate constructions from the illustrative embodiments discussed above which are fully equivalent. Consequently, it is not our intention to limit our method and control system for operating an oil well and a well using our control system to the particular embodiments disclosed. On the contrary, our intention is to cover all modifications and alternate constructions coming within the spirit and scope of our method and control system for operating an oil well and a well using our control system as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of our invention: