Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02272269 1999-OS-18
CLT005
APPLICATION FOR PATENT
INVENTORS: GORDON L. RASMUSON
PAUL PIGUE
ZAKI D. HUSAIN
TITLE: FLOW RESPONSIVE TIME DELAY
PUMP MOTOR CONTROL LOGIC
This invention relates generally to pumps that are located downhole within
wells for pumping
well fluid, typically petroleum products and water, which enter the wells from
oil or gas bearing
subsurface formations. This invention also concerns an electronic protective
system for changing
or deenergizing the speed of the rotary motor operated drive system of a
downhole pump in the event
that an abnormally low pump discharge flow exists, which might indicate a
temporary or permanent
cha.~ge in v:~e:l productivity er might indicate pump wear, damage or any
other pump or pump motor
CA 02272269 1999-OS-18
abnormality. More specifically, the present invention concerns a time delay
motor control circuit
which can cause pump slow down or shut down by changing or deenergizing the
electrical circuit
of a pump motor in the event abnormally low pump discharge flow is sensed by a
flow transducer
that continuously measures pump discharge flow at any location in the fluid
flow system and
transmits electrical signals representing pump flow. More particularly, the
present invention is
directed to a time delay motor control logic that is responsive to a low pump
discharge fluid flow
condition for slowing or shutting down a downhole pump and motor assembly and
yet permits pump
operation for a predetermined period of time under a condition of abnormally
low flow to prevent
premature pump shut-down when the low flow condition is temporary. The time
delay motor control
logic is designed to prevent the loss of pump productivity under circumstances
where the pump
driven by the motor is subject to fluctuations in discharge flow because of
variations in the gas
content of the fluid passing through the pump or because of the existence of
other well anomalies
of short duration. The present invention also concerns a fluid flow responsive
time delay pump
motor control logic that permits the pumping capability of a well pump to be
automatically matched
1 p with the production rate of a well and to change pumping speed
automatically in response to changes
in the production rate of the well.
Although the present invention is discussed herein particularly as it relates
to progressive
cavity pumps for production of well fluids from wells, particularly oil wells,
it should be borne in
mind that this invention is also applicable to the control of other rotary
well pumps, ~~.!ch zs
electrically energized submersible pumps, and is also applicable to the
control of various other
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electric motor operated equipment. Thus, the terms "pump", "downhole pump",
etc. are intended
to encompass various types of rotary surface and subsurface pumps that may be
used for motorized
production of liquid petroleum products and associated Liquids from wells and
is also intended to
encompass rotary electric motor driven apparatus other than pumps. The term
pump is therefore
intended only as an example and is not intended to limit the spirit and scope
of the present invention.
In cases where crude oil production wells are to be pumped, it has been the
practice to install
a production tubing string within a well, with a prog~rGSSing cavity fluid
lift pump being located in
the downhole environment at or near the lower end of the production tubing
string and below the
standing fluid level of the well, when the well is producing. A rotary drive
mechanism, powered by
LO a rotary electric motor is typically mounted to the well head and drives a
sucker rod string which in
tum drives the progressive cavity pump.
It is well known that the potential flow conditions of some oil wells tend to
fluctuate
significantly and sometimes rapidly. Thus, well pumps that are located in the
downhole environment
are often subject to temporary low liquid discharge. Under such conditions the
pump will ordinarily
be restored to its proper rate of liquid discharge as soon as the anomaly is
dissipated (typically only
a few seconds at a time).
Conditions of low liquid discharge of the pump can also occur for reasons that
have little to
do with the production characteristics of the subsurface formation or the
presence of gas in the well
fluid. In some cases, because of the contaminated or abrasive characteristics
of the well fluid being
ZO pumped, including the volume of entrained solids therein, the pump can
become worn so that its
liquid discharge capability is reduced. Before pump wear becomes excessive,
the discharge flow
fiom the pump is reduced below a pre-selected value, the pump should be
stopped. When conditions
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occur that impair the rotational capability of the pump mechanism, regardless
of the cause thereof,
diminished pump discharge flow will occur. Thus, according to the present
invention it is desirable
to continuously sense pump discharge flow and to deenergize the pump or
controllably slow pump
operation in the event pump discharge flow rate should fall below a
predetermined set point for any
of a number of reasons. It is desirable that the pump system have the
capability of accommodating
inherent fluctuations in flow measurement without permanently shutting down
the pumping
operation in response to a flow measurement anomaly that is only temporary.
If automatic pump shut down should occur as the result of a temporary well
condition or
pump condition, then valuable production fiom the well can be lost. It is
desirable to provide a flow
responsive pump cut-off system that effectively overcomes this problem. The
pump cut-ofl'system
of the present invention ensures that the well is shut-in under circumstances
where the pump could
become irreparably damaged if pumping should continue at the existing
operating speed, but also
insures that the well is not shut-in under circumstances where temporary
anomalies occur, such as
temporary lower pump discharge flow that quickly passes.
When pump start or restart occurs it is necessary to disable low flow
responsive pump cut-off
logic to provide for filling of the production tubing and for pump discharge
flow to exist within the
flow sensitive transducer. Thus the pump control system of the present
invention is provided with
a startup delay period that can be adjusted according to various well
parameters such as standing
fluid depth, tubing size, etc. to provide a field selectable time delay period
which must expire after
a start-up before the pump cut off logic circuitry is activated
Typically, when pump shut down is caused by conventional pump control
equipmPnr_, the
pump remains out of service until such time as well servicing personnel can
inspect the well and
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place the pump back on line. Since many wells are located in remote areas and
are seldom visited
by well service personnel, a deactivated downhole pump can remain deactivated
for long periods of
time thereby causing the production of the well during that period of time to
be lost. This is of
course an undesirable condition which finds its solution in the present
invention.
In accordance with the present invention, for detection of pump discharge flow
conditions,
a flow responsive transducer is located in the flow line, preferably in the
discharge line from the well
and continuously transmits a flow related electronic signal in the nature of a
voltage, a current, a
frequency, etc., via electronic control conductors to electronic control
equipment that is located at
the surface. These flow related electrical signals can be generated by any
suitable flow transducer,
such as an ultrasonic flaw meter, orifice type flow meter with a differential
pressure sensor, a turbine
type flow meter, thermal dispersion flow sensor, and the like which develop
electronic signals
representing flow of fluid through a flow line . In the event abnormally low
pump discharge flow
condition is detected that could cause damage to the pump or to the pump motor
assembly, and
remains beyond an allowable period of time, the control system at the surface
will deactivate or
1 S adjust the power circuit of the pump motor in a manner causing the pump to
shut down or causing
the pump to operate at a lower speed.
SUMMARY OF THE 1NVF~1TI0~
It is a principal feature of the present invention to provide a novel flow
rate responsive time
delay motor control logic for an electric motor, such as a pump motor for well
production for
example, which has the automatic electronic capability for determining the
production rate of a v, ell,
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periodically setting itself for the production rate of the well, determining
changes in the production
rate of the well and resetting itself responsive to changes in the production
rate of the well.
It is another feature of the present invention to provide a novel flow rate
responsive time
delay motor control logic for an electric motor which permits motor operation
of predetermined
duration following detection of an abnormal flow rate condition under
circumstances where the
abnormal flow rate condition does not continue beyond an electronically preset
period of time.
It is also a feature of this invention to provide a novel electronic flow
responsive time delay
pump motor control logic that is responsive to the output voltage signals of a
suitable flow
responsive transducer, such as an ultrasonic flow meter, for example, which
detects pump discharge
fluid flow conditions and which accomplishes shutdown of the motor drive of a
downhole pump
under circumstances where abnormally low pump discharge flow conditions are
indicated beyond
a predetermined maximum period of time.
It also a feature of the present invention to provide a novel downhole pump
control system
having an automatic time delay motor control circuit that is electronically
adjustable for a wide range
of time delay without necessitating the presence of or control by field
personnel and having the
capability of automatically and electronically controlling well production
according to the flow
parameters of the well even under circumstances where well flow parameters
change after initial
installation of the well pumping and flow controlling equipment.
It is another feature of the present invention to provide a novel time delayed
motor control
logic for a downhole pump system which incorporates a start-up timer circuit
that sets the time
interval for activation of the motor control logic and thus permits the puma
system tc become
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stabilized at the production rate of the well before the time delay motor
control logic circuit becomes
fully operational.
It also a feature of the present invention to provide a novel downhole pump
system having
an automatic time delay motor control logic that provides a digital readout of
the flow condition of
the pump and which incorporates a set level switch that can be manually
positioned to indicate the
set level position of the time delay circuitry, thus enabling field personnel
to quickly determine the
parameters for which the circuitry has been set.
It is also a feature of the present invention to provide an electronic time
delay motor control
logic system for downhoIe rotary pumps which accomplishes pump shut down or
changes the speed
of the pump responsive to the existence of an abnormally low pump discharge
flow that has a
duration exceeding a selected time period for which the electronic logic
system is set and having the
capability for restarting the pump motor for operation at the same or a
dif~'erent motor speed
according to the character and sequence of the pump discharge flow condition
that is detected.
t5 BEZIEF DESC tPTION OF THE DEZA~:n"1C'TS
The various objects and advantages of this invention will become apparent to
those skilled
in the art upon an understanding of the following detailed description of the
invention, considered
in light of the accompanying drawings which are made a part of this
specification and in which:
Fig. I is a diagrammatic illustration of a progressive cavity well pumping
system according
'.0 to the present invention, having an electric motor energized downhole pump
driven by a rotary
sucker rod string for pumping well fluid fiom the well bore through a
production ~sbss:g string and
with pumped fluid flow being detected by sensor means developing flow
responsive electronic
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signals which are transmitted to a control logic for use in motor control
according to well production
capability; and
Fig. 2 is block diagram illustration of an electronic circuit board being
constructed in
accordance with the principles of the present invention and showing features
for selective adjustment
of operating parameters of the time dzlay motor control logic which is
automatically operative
responsive to flow parameters of the downhole pump discharge.
Referring now to the drawings and first to Fig. 1, a progressing cavity type
rotary pump
shown generally at 10 is secured by an anchor 11 at a desired depth within a
production tubing string
12 that is located within a well casing 14 intersecting a subsurface
production zone 16 containing
liquid petroleum products to be produced. The liquid petroleum products,
typically crude oil,
typically accompanied by water and natural gas, migrate from the subsurface
formation and enter
the well casing 14 that lines the well bore 1 S via perforations 18 in the
well casing and typically rise
within the casing to a standing level well above the depth of the producing
formation. The standing
level of fluid within the well casing is determined by the character of the
producing formation. The
pump is located within the casing below the standing level of the well fluid.
Its location depth
within the casing is determined by the producing characteristics of the
subsurface formation and
various other parameters of the well and the pumping equipment. The
progressive cavity pump
defines a fluid inlet 20 in communication with the liquid standing within the
casing and has a fluid
discharge 22 which is open to the production tubing string 12. The pump 10 is
energized by a
rotating sucker rod string 23 which extends through the production tubing 12
and which is driven
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by a rotary electric motor 24 of a drive head 25 which is mounted to the
wellhead 26. The rotary
electric pump motor has a motor circuit 28 which receives its electrical
energy from a suitable source
"S" of electrical power supplying the electrical requirements of the oil field
being produced.
The production tubing string of the well is in communication with a flow tee
27 having a
flow line 29 connected thereto and arranged for delivery of petroleum products
to sales. Adjacent
to or mounted to the flow line 29 is a flow transducer having an electrical
signal processor output
at 31 representing the rate of fluid flow through the flow line, with the
electrical signals thus
evidencing the condition of pump discharge flow at any point in time. Any, of
several types of flow
transducers, such as ultrasonic flow meters, head type devices, turbine meters
or any of a number
of other types of flow meters may be employed for this purpose. As an example,
the flow transducer
30 of Fig. 1 is illustrated as an ultrasonic type flow transducer which is
attached externally of the
flow line 29 for measuring discharge flow of the pump by measuring the volume
of fluid flowing
through the flow line. The flow transducer 30 generates a flow responsive
electrical signal in the
form of a voltage or electrical current output at 31. This pump discharge
responsive electrical signal
t ~ is conducted via power and control conductors 43 and 44 to a control
console 46, to be discussed
in detail hereinbelow, and which is typically located adjacent the well being
produced or mounted
to the wellhead equipment in a position for visual inspection by well service
personnel. The fluid
flow related electrical signal is electronically processed by the
microprocessor circuitry of the control
console to provide an electrical signal output that represents the flow rate
of the fluid being
?0 discharged by the pump. The flow sensitive transducer 30 can be powered by
a 24- volt power
supply if needed or may be powered by any other suitable power source from the
control conso~ 46
via the power and control conductors 43 and 44. During normal operation of the
downhole pump
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the flow transducer 30 wilt sense fluid flow through the flow line 29, with
the fluid flow being
sensed representing the actual rate of pumped fluid flow being discharged by
the rotary downhole
progressing cavity pump 10. Electrical signals representing the rate of flow
within the flow line at
any point in time will be supplied to the electronic logic of the control
console 46 in the manner and
5 for the purpose discussed in detail hereinbelow. If the rate of Quid flow is
unusually low, evidencing
a pump discharge flow abnormality, this abnomlal condition is immediately
displayed by the control
console and if the abnormality continues beyond a preset period of time which
is considered safe for
the pump and pump drive mechanism, the logic of the control console will
deenergize or alter,
typically lower, the operational speed of the pump motor by appropriately
energizing or deenergizing
10 power and control conductors 26 and 28 of the driveled/motor mechanism 24 -
25. Thus, the pump
system is controlled so that the pump motor and pump will not become damaged
by heat build-up,
erosion, excessive wear, etc.
Referring now to Fig. 2, the control console, shown in partial section
generally at 46, is
provided with control circuitry which is housed within a console housing 48
having a door 49 which
is normally sealed to the housing. The door 49 is provided with an inspection
window typically
comprising a glass plate 50. If desired, the closure can be wire sealed,
locked or otherwise secured
to prevent its opening by unauthorized persons. Circuit boards 52
incorporating the time delay
motor control logic can be mounted within the enclosure. If desired, the
control console 46 may be
constructed with the monitoring and control logic being provided by a single
circuit board or
multiple circuit boards depending upon the design characteristics that are
desired.
To manually change any setting or manually re-start the motor control logic
circuit, Lh
housing closure must be opened to gain access to the outer circuit board 52 by
opening the closure
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door 49. The circuit board 52 of the present invention has visible references
and adjustment controls
to enable users to easily set or reset the control parameters of the control
circuitry. In cases where
the well pump control system is to be used in exceptionally cold conditions
that might influence the
operational characteristics of the solid state circuitry, a temperature sensor
54 may be mounted
within the housing cavity in position for sensing the temperature of the
housing. At a preselected
low temperature an electrically energized heater 55, supported by an
intermediate heat conductive
mounting plate 56, may be automatically energized for ensuring that the
temperature of the
electronics cavity and circuit board or boards is sufficiently high that the
electronic circuitry will not
be impaired by extremely cold ambient temperature conditions. It should be
home in mind that
control console heating systems of this nature are not of necessity unless the
ambient temperature
is sufficiently low that the operational characteristics of the control logic
can be impaired.
Referring now to Fig. 3 the front or display face 58 of the circuit board 52
is visible to service
personnel and provides a visual display of the operational characteristics of
the downhole pump.
The outer face of the circuit board will provide a display of five operational
conditions which will
l~ be visible to personnel upon inspection. The circuit board is provided with
a "SET FLOW/READ
FLOW" switch 60 that is a toggle switch which allows selection of "READ FLOW '
or "SET
FLOW ' circuit parameters. This switch 60 controls a light emitting diode
(LED) or liquid crystal
display (LCD) 62 having a digital display that is visible to service personnel
and provides a visual
display of the conditions of discharge flow of the downhole pump. At the "READ
FLOW ' position
of the toggle switch, the actual output voltage of the flow meter is
displayed, which represents the
volume of flow through the flow meter. When the toggle switch 60 is moved to
flee "SET FLO~~~'
position, the digital voltmeter of the display 62 will indicate the
preselected threshold voltage of the
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flow meter actuated motor control logic for pump motor cut-off or pump motor
speed adjustment.
When the pump control logic incorporates a microprocessor the display 62 will
display actual flow
rates in any engineering unit instead of voltage.
The circuit board 52 is provided with "STOP SET" and "LOW SET" potentiometers
64 and
65 each having manually positioned adjustment elements 66 and 67 which allows
setting the
threshold voltage for the low flow set point and the threshold limit to stop
the pump motor
completely. The actual voltage range is from approximately 1 volt to about 5
volts for the circuitry
that is shown, but may be provided in any voltage range that is suitable for
the intended purpose.
With microprocessor circuitry these set points could be the actual flow rate
in any designated
engineering unit. The "low set" potentiometer 65 adjusts the set point for the
desired flow rate
below which, if the flow remains for longer than a selected period of time,
typically measured in
seconds, the pump motor is to be shifted to a low speed condition by control
circuit activation.
To adjust the flow adjustment set point, the momentary toggle switch is held
at its "SET
FLOW ' position as shown in Fig. 3 while the "LOW SET" potentiometer is
adjusted manually by
moving it to the desired voltage setting as indicated by potentiometer
reference marks and as
confirmed by the digital voltmeter display 62. This display could also be in
desired engineering unit
of flow rate.
The display Face of the circuit board 52 is also provided with a cut-off delay
adjustment in
the form of a cut-off delay pin-socket jumper 68 being connected across jumper
contacts for the
purpose of selecting one of a number of time delay periods of a "LOW DELAY"
timer circuit 69.
Adjacent to or on the "LOW DELAY" potentiometer 69 are spaced u'dicia 1-10
wh~c?: are reforen~e
indicia typically indicating a selected cut-off delay in terms of seconds or
other preselected range.
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The delay time of the prefen ed embodiment can be adjusted between one second
and to a maximum
of about 10 seconds but it should be borne in mind that other time delay
period selection is within
the spirit and scope of the present invention. For microprocessor based
circuitry this time delay can
be confirmed by front panel, keyboard or other communicating devices to the
circuit board. During
actual operation when the flow rate drops below the pre-selective cut-off race
and remains below that
flow rate for a period of time equal to or greater than the delay period that
is defined by the cut-off
delay potentiometer, the motor adjustment switch or other control actuator of
the pump motor will
be activated. When this occurs, the motor adjustment switch will either
disconnect the power switch
of the motor for pump cut-off or select the appropriate motor control circuit
for pump operation at
a reduced speed. The desired cut-off or motor speed change delay is typically
dependent on the
amount of gas that is entrained in the well production fluid and thus flows
through the flow line for
detection by the flow transducer and should be adjusted accordingly. This
adjustment can be
optimized in the field by observing the combined effect of "set flow" and "low
speed delay". For
example, when a well has a low gas content flow stream, the low speed delay
setting may be as low
t 5 as one second. In that case, the flow rate through the flow meter must
remain below the low speed
flow rate delay set point for a continuous period of one second as defined by
this setting for the
motor speed change circuit to be activated. If the flow rate signal fluctuates
above and below the
"set flow" rate but does not remain above the time delay threshold for at
least one second, the time
delay threshold will not have been exceeded because it is reset each time the
flow rate exceeds the
?0 low speed flow rate set point.
Also shown on the circeit board 52 is a start-up timer circuit sr'.o~~
gererally at i2 which
is provided in the form of a piNsocket connector having a plurality of pairs
of jumper pins such as
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shown at 73, each being connections for a timer circuit having a specific time
period. For selection
of a time delay period that is defined by one of the timer circuits a jumper
element 74 is connected
to a selected pair of contact pins thus completing the selected timing
circuit. Each pair of jumper
pins of the preferred embodiment are arranged in approximate 10 minute
increments of time with
the upper pair of jumper pins setting a start-up time period of 10 minutes,
the second pair of jumper
pins 20 minutes, the third pair 30 minutes, and so on, for a maximum of 90
minutes when the jumper
74 is connected across the bottom pair_of pins. When microprocessor based
circuitry is employed
any of the timing periods can be arbitrarily preset, thus enabling the pump
control logic to be
"tailored" precisely to the production characteristics of the individual well
that is being controlled.
As shown in Fig. 3, the start-up delay time period is set at 50 minutes since
the 50 minute pair of
pins has the jumper 74 while the remaining pairs of pins are open. The start-
up delay timer sets the
timer interval for the activation of the motor control logic. Only one pair of
pins 73 will be active
at any point in time. The time period that is established by the time delay
setting prevents motor
control logic activation until the pump has operated for a sufficient period
of time to fill the flow line
and thus provide an accurate fluid flow signal from the fluid flow transducer.
The length of time
interval should be field estimated based on the depth of the well, pump
capacity, etc. which
determine the approximate time it takes for the liquid to fill the meter line.
At the center of the circuit board 52 is provided a start button 76 which
starts the motor and
initializes the motor control logic circuitry and thus initializes the timing
sequence that is selected
ZO by the jumper position of the "start-up" delay timer 72. For initiation of
the start-up timer, the start
button is depressed. An extended remote switch rt-may he ~_n_stalled in pa~-
aliei connection wiil: tre
circuitry of the START button 76 which may also accomplish the initialization
sequence of the
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CA 02272269 1999-OS-18
controller. If at any time during normal operation the "start" button is
pressed, the timed delay
motor control logic will be initialized and the "start-up timer" delay will be
reset in accordance with
the jumper setting in the "start-up" timer 72.
'The circuit board 52 is also provided with four light emitting diodes (LEDs)
which are
indicated at 78, 80, 82 and 84 and which respectively indicate conditions of
the pump, flow through
the flow sensor, the condition of the start-up delay circuit and the low pump
speed. The LEDs 78,
80, 82 and 84 are each bi-color (red and green) LEDs which show no color in
the respective "off'
positions thereof. If all of the LEDs are off, there is provided an indication
that there is no power
to the circuit board or an indication that all of the LEDs are damaged. If
only one or two LEDs are
off, there is provided an indication that the circuit board is operative but
the LEDs that are offmay
be damaged.
:-When the pump LED 78 is showing green, the pump circuit is on and the pump
motor is operating at either its normal pumping speed or at a pumping speed
that is slower than the
normal pumping speed. Conversely, when the pump LED is showing red, the pump
motor circuit
is off, and pump stoppage has been activated by the time delay motor control
logic. Absence of
either of the colors red or green provides an indication that the logic
circuitry is not properly
operative or the LED is defective. If pump cut-off has occurred, before
reactivating the time delay
motor control logic circuit, service personnel should ascertain the cause of
the pump shut-off because
indication has been provided to the circuitry that the pump flow condition was
abnormally low and
remained at this abnormally low condition for a time period equaling or
exceeding the preset time
period for motor shut-off. In other words, the preset valises of the low pow
rate set by the vendor
have been exceeded and low flow induced automatic logic controlled pump slow
down has not
CA 02272269 1999-OS-18
corrected the low flow condition either because of a mechanical problem with
the downhole pump
or a temporary problem with the well (excess gas for example) which influences
the flow of well
fluid into the well. Obviously, if the problem is of mechanical nature,
involving the pump, then
service personnel will need to determine if appropriate adjustments can be
made to resume normal
pumping.
Flow: If the LED 80 is showing green, the flow rate through the pump discharge
line 29
monitored by the flow transducer 30 is_above the STOP point that is
established by the adjustment
position of the potentiometer 64. If the flow LED is showing red, then the
flow rate through the line
monitored by the flow transducer is below the STOP set point. In this case,
the pump may be
operating at a lower pumping speed, responsive to the low speed potentiometer
69, in which case
the low speed LED 84 will be showing green and the particular slow speed that
has been
automatically selected by the pump control logic will be displayed by the
digital volt meter 62. If
the LED 80 is flickering red and green, then there is provided an indication
that the flow through the
flow meter is fluctuating above and below the STOP set point. In this case,
the pump will be
permitted to continue its normal operation until such time as the cut-off
delay period that is
established by the setting of potentiometer 64 has been exceeded. The time
delay motor control
logic will operate to slow or de-energized the pump motor only under
circumstances where the Qow
rate through the pump discharge line remains below the cut-off flow rate set
point for a period
exceeding the time delay period that is pre-set by the low speed and cut-off
timing circuit 68.
Start-u~: When the LED 82 for the start up circuit is showing red, the circuit
is in operation
but the initial "start-up" delay period that is established by the position of
jumper ?4 of ti:e start-up
delay circuit 72 assuming the selected start-up delay period of the start-up
delay timer 72 has not
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CA 02272269 1999-OS-18
expired. In this case the operator should check the "pump" LED 78 to confirm
that the pump is in
operations. If the "pump" LED is Been, the circuit will be active after the
preselected START-UP
delay period has expired. If the "start-up" LED 82 is green, but the "pump"
motor is not running
and the motor was deactivated during the start-up time delay period by the
time delay motor cut-og
S logic. The circuit must then be reset by depressing the "start" button so
that a start-up holding circuit
component of the start-up circuitry will be initiated and will remain active
when the start buttoa is
released. As a caution, if the "pump" LED 78 is red, the cause of the
deactivation must be
ascertained before resetting the circuit.
If the start-up LED is showing GREEN, the START-UP time delay period has
expired and
the time delay motor cut-off logic is active and will be immediately
responsive to conditions of flow
through the pump discharge line that is monitored by the flow transducer.
The condition shown in Figure 3A is a normal condition indicating pump
operation and flow
through the flow line that is detected by the flow transducer assuming that
the normal pump
operation LED 78 is showing green and the low speed pump operation LED 84 is
showing either red
or green. When the start-up LED 82 is showing RED the start-up circuit is
energized but the initial
start-up time delay has not expired and the flow responsive time delay is nvt
operative. If LED 82
is showing GREEN, then initial time delay set by the START-UP delay jumper has
expired and the
circuit is armed. In this case, pump slow-down or shut-off will occur
automatically when the
particular settings of the potentiometer 64 and 65 have been exceeded.
When all of the LED's 78, 80, 82 and 84 are GREEN, this would normally
indicate that the
time delay motor control logic is operative and initial start-up d;,lay period
has expired. The bree..
LEDs also indicate that flow in the flow line is above the set point for pump
slow-down or cut-off
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CA 02272269 1999-OS-18
and that the pump is running. Ln this position, the adjustment element 66 of
the potentiometer 64
will be adjusted to provide appropriate flow rate data, i.e., 2.00 volts in
the digital flow meter display
62 corresponds to a specific flow rate which is optimized for a particular
well, based on well
equipment, meter size, meter selection, gas content of the well fluid, meter
sizing parameters,
secondary instruments of the meter, etc.
When the circuit board 52 is shown with the pump and flow LEDs 78 and 80 green
and the
start-up LED 82 is green an indication is provided that the initial time delay
period for start-up has
expired and the time delay circuit is operational. There is also provided an
indication that the flow
being detected is above the pump slow-down or cut-off set point of the
potentiometer 65 and the
(0 pump is operating.
It should be noted that when the toggle switch 60 is in its "read flow"
position, opposite the
position shown in Figure 3, the actual flow condition through the flow line
sensed by the flow
transducer is represented by a numerical read-out on the display panel of the
digital volt meter 62.
When this actual flow condition is below the STOP-SET limit set by the
potentiometer 64 and for
a period below the preset time limit established by the pin located of the low
speed and cut-off delay
jumper 68, then the motor drive for the downhole pump will be de-energized by
the time delay motor
control logic. In this case the "flow" LED 80 will be showing red because the
condition of pump
flow is below the preset limits established by the STOP SET and LOW-FLOW
potentiometers 64
and 65. The pump flow LED 80 in this case is green, indicating that, although
flow is being the set
flow rate, the time delay period set by the low speed and cut-off switch 68
has not been exceeded.
Also in Lhis condition, the start-up circuit LED 82 is red, i_~dicating that
Lhe i.~,itial st:~.rt uelay period,
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CA 02272269 1999-OS-18
as set by the selected time period switch of the multiple timer switch 72, has
been exceeded and the
pump speed control and cut-off circuit logic has been activated.
The pump motor control logic has the capability for controlling operation of
the pump motor
at a normal pumping speed, which is referred to herein as "high speed", or for
setting the operating
speed of the pump at any one of numerous operating speeds that are determined
by the productivity
and changes in productivity of the well being produced. When an anomaly occurs
in the rate of flow
and persists for a time period equaling or exceeding a time period that is
preset in the control logic,
the control logic will automatically decrease the motor spced by a
predetermined increment. If
operation of the pump motor at the decreased speed causes the low flow
condition to become
corrected, motor operation will be continued by the control logic at the low
speed for a period of
time. The control logic will periodically reset the pump motor speed to its
high speed to determine
if the flow anomaly is temporary and has become corrected. If the low flow
condition then
subsequently occurs, indicating that the low flow condition is beyond
temporary nature, then the
motor control logic will return the motor speed to a lower incremental speed.
If the low flow
condition remains prevalent at the selected lower incremental speed, then the
flow responsive motor
control logic will further reduce pump motor speed, and so on, until the speed
of the pump has
matched the productivity flow of the well being produced. Logically, if the
productivity of the well
should then increase or decrease the motor control logic will respond to the
changed flow that is
sensed by the transducer and will then increase or decrease the pump speed to
accommodate the
changed condition.
The LED display of Fig. 3 ca.~ also indicate the possibility that a condition
of ab:~rormally low'
flow exists through the flow line monitored by the flow transducer, indicating
a pump or motor
19
CA 02272269 1999-OS-18
problem or indicating that more than the usual quantity of gas is passing
through the meter along
with the fluid. Under this condition the start-up delay LED 82 will show red
while the "Pump 78",
"Flow 80" and "Low speed 84" LEDs will each show green. If this condition
persists for a period
of time equaling the preset timing sequence of the low speed delay timer
circuit 68, the flow
responsive motor control logic will actuate the motor control circuit and
reduce the speed of the
rotary pump. Typically, a condition of excess gas induced low flow will exist
for a short period of
time and, after the excess gas has been dissipated, the well will then return
to its normal productive
capacity. Periodically, the timing sequence of the logic circuitry will return
the pump motor to its
normal operating speed so that well production can be resumed at its normal
rate. If the normal
pump speed cannot yet be maintained, the pump motor will be returned to a
lower incremental speed.
If, at any time the pump is operating at a speed lower than its normal
operating speed, the logic
circuitry, again responding to a condition of low pump discharge flow, will
further reduce the speed
of the pump motor by increments until the pump speed will have become matched
with the fluid
production rate of the well at that time. Thus, as the well increases or
decreased in fluid
productivity, the logic system will match the pump speed with well
productivity.
When the LEDs 78, 80 and 82 are each shown to be in their normal operating
condition,
showing "green", while the momentary toggle switch 60 is in its "read flow"
position, the circuitry
will be operating with the flow rate above the slow-down or cut-ofI'condition
set by switch 64. The
circuit is now activated as initial start up delay has been exceeded which is
indicated by red start up
LED 82. When all LED's are red there is provided an indication that the pump
circuit is energized
and the pump has been deactivated because the Ilow rate rer?rained below the
"set flow" condition
over a period exceeding the switch setting 68.
CA 02272269 1999-OS-18
As a general caution, after a power failure to the time delay motor cut-off
board, the cut-off
logic will activate upon power resumption, and the "start-up timer" will be
initiated in accordance
with the setting of the switches 74 of the start-up timer 72.
In view of the foregoing, it is evident that the present invention is one well
adapted to attain
all of the objects and features that are hereinabove set forth, together with
other objects and features
which are inherent in the apparatus disclosed herein.
As will be readily apparent to those skilled in the art, the present invention
may be produced
in other specific forests without departing from its spirit, scope and
essential characteristics. The
present embodiment is therefore to be considered as illustrative and not
restrictive, the scope of this
invention being defined by the claims rather than by the foregoing
description, and all changes which
come within the meaning and range of equivalence of the claims are therefore
intended to be
embraced therein.
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