Note: Descriptions are shown in the official language in which they were submitted.
35~5~3 ~
This app~ication is related to copending Canadian
Patent Application Serial No. ~25,144, filed April 22, 1975
...............................................
3ack~rouhd of the In~en- i n. This invention relates
to oil wells and more particularly to an automatic well cutoff
system for pumping oil wells.
In the production of oil, a well is drilled to $he
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 bot~om of the well. A desirable mode
of operation is to pump the oil when~ver there is sufficient
oil in the pool and to stop the pumping when there is not -
sufficient oil in the pool.
Advantages of this desirable mode of operation are
that the pump automatically reaches its optimum pumpiny 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 contxol systems for providing such an automatic
pump-off control a~ oil wells. Examples of such prior art in-
clude U.S. Patent No~ 2,550,093 issued April 249 1951 to G~ Ar `-
Smith and U.S. Patent No. 2,316,494 issued April 13, 1943 to
R. TiptonO In the Smith patent, a valve activates an elec~rical
circuit which causes the pump to be shut down after a predeter-
mined time interval in the event the produced oil ceases to flow
through the valve. In the Tipton patent, a clock is caused ~o
run in response to there being no produced fluid, thus c~using
the pump to periodically
~ "
mb/d~
s ~
.
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 1uid 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 re-
quired or 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 automati-
cally stop when it has pumped off the oil, or or 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 o time during which
oil is ~eing 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 OperatiQn
of the pump is automatically stopped when the fluid in the bore-
hole is depleted;
It is a further object of the invention to completely
shut of the system after a predetermined number of shut-down `
cycles should proper flow not be reestablished; 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.
--2--
,
.
~ `
~q~
The objects of the invention are accomplished,
generally, by a system which produces signalsindicative of
the normal operation of the well pumping installation which
axe used in conjunction with timing circuitry which determines
5 the percentage o~ time of normal operation during a given time
period, 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 non-
productive recycles.
These and other objects, features and advantages of
the invention will be more readily understood from the follow-
ing 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, illus-
trating 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 diagrammatic sketch illustrating the
component parts of an alternative embodiment of the present
invention;
FIG. 6 schematically illustrates, partly in block
diagram, the electrical circuitry used with the embodiment
according to FIG. 5;
FIG. 7 schematically illustrates yet another alterna-
tive embodiment of the present invention;
FIG. 8 is a diagrammatic sketch illustrating the
-3-
, . . , . :. . ... .,...... . ., , :
component parts of still another alternative embodiment of the
present invention;
FIG. 9 schematically illustrates, partly in block
diagram, the electrical circuitry used with the embodiment
according to FIG. 8; and
FIG. 10 illustrates schematically still another
alternative embodiment of the present invention.
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 energi~ing ignitlon current supplied through lead 1~.
A valve assembly 19, shown in more detail in FIG. 2,
i5 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 sub-
stantially 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
-4-
~ '
.. ... . . .
.
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 con-
structed in accordance with copending Canadian Patent Application
Serial No. 179,634, filed August 27, 1973, 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 o~ 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 beiny 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 c~lindrical ~alve housing 24
above the valve seat 33 is enlarged with respect to the upper
section of the valve housing 2~, 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 FIG.'s 1 and 2, it should be appreciated that as the ~luid
is pumped from the well 10,` it enters the flow pipe 12 and is
pumped through the valve assembly 19. In reference ~specially ~ `
_5_
: ' ' . . . , ,:
.. . : , . . .
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 3a 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 Elow 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 integration 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 in-
cluded 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 nul[~er is three,
bearing the numerals "l", "2" and ll311, 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 "l" will be lighted by a red light on the monitor 46 and
the numerals "2" and "3" will be sequenkially illuminated on
.. . . .
' . , , '
,
f `~
subsequent shutdowns. A recorder connection 4~ 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,
Baraboos, 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.
HP56~6.
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 fifty percent of the time. In response
to such ancdverse 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 com-
ponents of the circuitry of FIG. 4. Although the oscillator
50 has been described as being set at twice the frequency of
-7-
' ' ,' . . ,.' ' ' ' ;'", .',.., '', ,' " :, " , ., ., :,' ..
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 twenty-five percent
of the time. It should also be appreciated that it is prefer-
able 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 fifty
percent is theoretically the perfect condi~ion, 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 forty percent of the time. For
this purpose, a clock 170 having an output connected to counters ;
52 and 53 is used to supply the given period of time and can be
preset for any desirable time period, such as one minute. The
clock runs only during the normal pumping period and is started
by the single output of the pump-up timer 42 transmitted along
conductox 171. The clock is stopped by the shutdown signal
from the single shot multivibrator 55 transmitted along conductor
172.
Counters 52 and 53 can be of the type having conven-
tional shift registers which are clocked out into the comparator
54 upon receiving the clock pulse periodically, for example,
every minute. Thus, during the time between the termination of
the pump-up period and the shutdown signal generated by the
single shot 55, the clock will transmit output pulses to the
shift registers at the predetermined intervals. By then com-
pariny the outputs of counters 52 and 53, the apparatus `
' ' ' ,, , ,, ' ', .
determines whether the percentage of time the switch 25 has
been closed is at, above/ or below the preset ~alue.
The output of clock 170 is also connected to one
input of an AND gate 173 which is used in the reset circuit
for the scaler 45. A reset line 174 connects the AND gate 173
to the scaler 45. The AND gate receives as a second input the
output from an inverter 175. The inverter 175 receives the
output signal from comparator 54, inverts the signal and -
transmits it to the AND gate 1730
The output of the single shot multi~ibrator 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, -twenty minutes. `~
The shutdown timer 41 and the pump-up timer 42 each contains
a single shot mul-tivibrator 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 o~ the coil 63 being grounded. The
relay 64 has a pair of normally open and normally closed con-
tacts. 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 con-
nected to a power supply, illustrated as being a battery 70
which is of adequate voltage to maintain the relay 64 in the
_g_ ~ '' ''''
. ~ .
.. . , ,, . ., . ' ~ ~ ' , ' . : ', . . ' . :.
, , , . . " . . ~, . . .
~
latched position. The lower normally open contact of r lay 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 o~ relay 66. The lower wiper
arm o 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.
Th~ 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 groundedO
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 con-
nected through a spring-loaded normally closed switch 85 back
to the ungrounded side of the coil 82 of relay 83.
In the operation of the circuit of FIG. ~, 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 sing~e shot multivibrator 55 which
occurs on the conductors 60 and 80. Such a pulse appearing on
-I0-
the input of the shutdown timer 41 causes the timer 41 to count
for a predetermined time interval, for example, four hours.
Simultaneously with the production of this signal upon conduc-
tor 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 ~enerated at the output of the timer 41 which activates
the relay 66. This causes the xelay 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 predeter-
mined time, for example, twenty minutes, and thereafter which
generates a single pulse of its own which is coupled bac~ to
reset the pump-up timer 42, the shutdown timer 41 and the
counters 52 and 53 in the inteyration 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 posi-
tions 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
::
--11--
, . . . , , , ~ .. .
~s~
in. After the system has been shut down three times, unless
reset in the interim by a pulse on the reset line 174, three
pulses will have been produced by the single shot multivibrator
55 and thus the scaler circuit ~5 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 p~ping 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. Before the occurrence of the
predetermined number of unproductive cycles, a logic "0" at the
output of comparator 54 causes a logic "1" to be couplsd into
the AND gate 173 which together with the clock pulse will cause
the scaler to be reset.
Referring now to FIG. 5, an alternative embodiment o~
the invention is illustrated with respect to a well pumping
operation similar to that illustrated in FIG. 1. However,
instead of using a valve to indicate the amount of fluid flow
within the flow line 12, means are provided to monitor the load
current of the pump motor (illustrated in more detail in FIG. 6)
to provide an indication of the well pumping operation. The
circuitry is provided within the controller panel 100 to monitor
the load current of the pump 101. A switch 102 is located on
the walking beam 103 and is electrically connected into the
circuitry within the controller panel which is further illus-
trated in FIG~ 6. The switch 102 is preferably one or more
mercury-capsule type switches that are mounted on the walking
beam and can be arranged to be opened or closed as desired upon
either the up or the down stroke of the walking beam.
Re~erring now to FIG. 6, which schematically illus-
trates the circuitry used with the apparatus of FIG. 5, there
-12-
is shown a motor 101 which has power supplied thereto by any
feasible electric power source that would be connected to a
set of input terminals 105, 106 and 107. This power source
may supply three-phase AC power, and the primary 108 of a
transformer 109 is connected in series with the phase which ;~
is connected to the terminal 107. The secondary coil 110 o~
transformer 109 is connected to a difference amplifier 111
.
through switch 102 which is controlled by the walking beam 103
(FIG. 5) such that the voltage is applied only at such times
as determined by the position of the walking beam. A second
transformer 112 supplies a reference voltage ~rom input ter-
minals 113 and 114 to an additional input of the difference
amplifier 111. It should be appreciated that the difference
amplifier 111 is conventional and is preferably arxanged to
supply an output voltage at such times as the voltage applied
to transformer 109 exceeds the voltage applied through trans~
former 112 to the difference amplifier. It should also be `~ -
appreciated that even though the switch 102 can be activated
to close upon either the down stroke or the up stroke of the
walking beam 103, the preferred embodiment contemplates that
the switch is closed on the up stroke to indicate that the
fluid, for example, oil, is being lifted by the pump. As is
well known in the art, the motor 101 draws more current when
oil is being lifted than when pumping dry. In such a case,
.. .. ." .
the difference amplifiér produces an output signal which is
applied to the coil 113 of relay 114. The wiper arm 115 of
the relay 1l4 is grounded, and the normally open contact 116
is connected to the oscillator 117. The output of the oscil-
lator 117, which operates in the same manner as the oscillator
50 of FIG. 4, is connected into a counter comparable to the
counter 52 of FIG. 4.
In the operation of the circuitry of FIG. 6, as the ;
-13-
'. ' ' ,' ' ', ~ ";'~ '''"' ' '., ..''' ' ', .'',~',''' '
.. .. . .. , . : ,.... . . . ..
switch 102 closes on the up stroke of the walking beam 103, the
primary coil 108 draws current through the motor 101 and this
signal is applied to the difference amplifier 111 in an amount
such as to be greater than the signal applied through trans-
S former 112 and a voltage is thus applied to the coil 113 of
relay 114. This causes the ground to be applied to the contact
116 and the oscillator 117 thus causes pulses to be coupled
into an appropriate counter. Thereafter, the circuitry operates
in a similar fashion as that illustrated with respect to FIG. 4
and comparisons are made with another variable frequency oscil-
lator and its associated counter to determine whether the
system is operating in a normal fashion for a predetermined
percentage of time during a given time period. Assuming that
the system is not operating for the predetermined percentage
of time in a normal fashion, then the system proceeds to shut
down and be recycled as previously discussed with respect to
FIG. 4. `-
Referring now to FIG. 7, there is illustrated an
alternative embodiment of the present invention wherein a
pumping apparatus similar to that illustrated in FIG. 5 is
illustrated but which uses a hydraulic load indicator 120
manufactured, for example, by the J. M. Huber Corporation and
which is installed within the sucker rod string 121. This
type of indicator produces a hydraulic pressure signal of
100 pounds per square inch for each 1000 pounds of rod weight.
Such pressure is carried by the hydraulic line 122 to a
hydraulically-operated pressure switch 123, for which the
pressure mechanism of the switch is adjustable. In a typical
example, the pressure switch is set at 800 pounds per square
inch as a threshold pressure so that the pressure switch 123
sends an electrical signal at its output leads which can be
used whenever the pressure exceeds 800 pounds per square inch.
-14-
- :~
:
The electrical signal is coupled by means of conductor 124 to
the input of a NOR gate 125 whose output is coupled into one
input of AND gate 126. The other input to AND gate 126 is :~
coupled to the output of a clock 127 which produces electrical
signals on each down stroke of the waiking beam 128. The
output of the AND gate 126 is coupled to a coil 128 of relay
129. The wiper arm 130 of relay 129 is grounded, and the
normally open contact 131 associated therewith is coupled into
the oscillator 132 in a similar manner as is illustrated in :`
FIG. 4 and the output of the oscillator 132 is coupled into
an appropriate counter, for example, as illustrated in FIG. 4
with respect to the counter 52~
It is well known in the art, for example, in U. S.
Patent No. 3,306,210 to Harvey W. Boyd et al, that during the
down stroke of the pump, the absence of fluid in the borehole
causes the hydraulic load indicator 120 to have an excess of
weight on the sucker rod string and the switch 123 causes an
electrical signal to be coupled into the NOR gate 125. A "1"
applied to the input of NOR gate 125 causes a "0" to be coupled ~
~:-- :
into the input of the AND gate 126 which causes a "0" to be
applied to the coil 128 and the relay 129 is thus not activated. :.
In such an instance, the ground is not applied to the oscillator
132 and thus no pulses are coupled into the counter. In the
normal operation of the pumping sequence, a "0" is applied to
the input of the NOR gate 125 and a "1" is thus coupled into
the AND gate 126 along with a signal from the clock 127. This
produces a "1" on the coil 128 and the ground is applied to the
input of the oscillator 132 which causes pulses to be coupled
into the counter as indicative of a normal pumping sequence.
It should be appreciated that even though the
preferred embodiment contemplates the use of a clock 127 to
generate pulses indicative of the downward movement of the
., .
-15~
,,,
., . . . . ~ ~....... . ..
.
' ., , ' ':: ' .. ' ~ '~
walking beam 128, a switch could also be used as is illustrated
with respect to FIG.'s 5 and 6 to couple a voltage source into
the AND gate 126.
As previously explained with respec~ to FIG.'s 4, 5
and 6, the apparatus and circuitry according to FIG. 7 operates
in a very similar manner in that the normal pumping,sequence
causes the relay 129 to he activated for each pumping stroke '~' '
in which oil is being produced and that pulses will be coupled '
into a counter similar to counter 52 of FIG. 4 and that the
remainder of the circuitry of the counting box 40 can be used
to determine whether the pump is pumping fluid for at least a
predetermined percentage of time during a given time interval.
Referring now to FIG. 8, there is illustrated an
alternative embodiment of the present invention wherein a
strain gauge 150 is attached to the walking beam 151 in a
manner well known in the art to determine whether the walking
beam 151 is experiencing a normal amount of stress which
.. . .
follows from the normal pumping sequence of pumping fluid,
for example, oil, from a producing oil well. A switch 152,
for example, as illustrated and discussed with respect to
switch 102 of FIG. 6, is utilized for measuring the stress ~
on either the up or down stroke of the walking beam 151 as ; ,
desired. The output of the strain gauge 150 is connected to
an input terminal 153 within the controller panel 154 and is
amplified by an amplifier 155 and coupled through switch 152
into a difference amplifier 156. A reference voltage 162 is
coupled into another input of the difference amplifier 156.
The output of the difference amplifier 156 is connected to a
coil 157 of relay 158 which has its wiper arm 159 grounded. -~,
The normally open contact 160 associated therewith is connected
to the oscillator 161 which has its output connected into a
counter such as counter 52 of FIG. 4.
-16-
,
In the operation of the apparatus and circuitry
illustrated in FIG.'s 8 and 9, the electrical signal as ~
measured by the strain gauge 150 is compared with the reference ~ ~ -
voltage 162 on the up stroke of each cycle of the walking beam
151 which causes switch 152 to close. For each such cycle that
the stress exceeds a given level, the relay 158 is activated
and the ground is applied to the oscillator 161. With ~ch ~ -
cycle of the pump that the stress is less than normal, the
difference amplifier provides no output and thus no ground
will be applied to the oscillator 161. For each normal cycle ;~
of the pump, i.e.~ one in which oil is being pumped, the
oscillator 161 is grounded and pulses are connected into a
counter and the sequence thereafter of the circuitry functions :
as is discussed above with respect to FIG. 4.
Referring now to FIG. 10, there is schematically
illustrated a well pumping installation having a conventional
pumping apparatus at the earth's surface, for example, as ;
illustrated with respect to the apparatus of FIG. 5, and
having tubing 180 passing from the earth's surface to the
location of the fluid 181 within the well and which is to be
pumped to the earth's surface. Casing 182 is maintained
between the earth formation and the interior of the well.
A conventional pump 183 is connected to the sucker rod 18
and is arranged in a manner well known in the art to pump the
fluid 181 to the earth's surface through the tubing 180. A
small tube 185 is lowered into the well alongside the tubing
180 and has therein a differential pressure gauge or other
such conventional device therein for transmitting a signal
to the earth's surface indicative of the liquid level within
the well being beneath the sensor or other detector located
within the tubing 185. The tubing 185 is connected by conduit
186 at the earth's surface to a switch 187 which generates an
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electrical signal at its output in response to the sensor
within tube 185 being above the leveI of the fluid in the
well. The electrical output of switch 187 i5 connected into
the input of an inverter 188 whose output is connected into
one input of A~D gate 189. The other input to the AND gate
189 is connected to the output of a clock 190 which generates ~ ,
electrical pulses in coincidence with the movement of the
walking beam 191 associated with the pumping apparatus. The
output of AND gate 189 is connected to the coil 192 of relay
193. The other side of coil 192 is grounded and the wiper
arm of relay 193 is also grounded. The normally open contact
194 of rela~ 193 is connected to oscillator 195 in a manner
similar to the other embodiments illustrated herein, for
example, as is illustrated and described with respect to FIG. 6.
In the operation of the apparatus and circuitry which
is schematically illustrated with respect to FIG. 10, during
the normal pumping sequence the sensor located in tube 185 is
located beneath the fluid level 181 within the well and no
signal is generated by the switch 187. Thus, a logic "0" is
applied to the input of the inverter 188 and a logic "1" is
applied to the input of the AND gate 189 as is the output of
the clock 190. Thus, as the pump operates, a signal is pro-
duced at the output of AND gate 189 each time the pump cycles
while the oil or other fluid within the well is above a pre-
determined level. This causes the relay 193 to be activatedwhich causes the ground to be applied to the oscillator 195
and the circuit thereafter operates in a manner as described
with respect to FIG. 4. Thus, this circuitr~ makes a deter-
mination as to whether the oil within the well bore is at or
above a predetermined level for more than a given percentage
of time during a given time interval.
It should be appreciated that other means are well
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~ 6~
known in the art for determining the level of the fluid 181
within the well, for example, by acoustic sounding wherein
acoustic waves are transmitted from the earth's surface to
the surface of the fluid and the returning acoustic waves
are measured for time of travel from the earth's surface to
the fluid interface to determine the depth of the fluid within :~
the well. Thus, in a manner analogous to that described with ~ .
respect to the apparatus of FIG. 10, such acoustic sounding `~
methods can be used to indicate that the fluid level is at a
certain level for at least a given percentage of time during
a predetermined time interval.
Thus it should be appreciated that there have heen
described and illustrated her~in 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 normal sequence of
pumping fluid. By way of specifi.c example, the use of a float
valve well known in the art can be used to generate an electri-
cal 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, mechani-
cal 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
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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 being pumped, 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.
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