U.S. patent application number 09/747831 was filed with the patent office on 2001-09-13 for pumpjack dynamometer and method.
Invention is credited to Mills, Manuel D..
Application Number | 20010021347 09/747831 |
Document ID | / |
Family ID | 46257353 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021347 |
Kind Code |
A1 |
Mills, Manuel D. |
September 13, 2001 |
Pumpjack dynamometer and method
Abstract
A dynamometer readout (42, 46) and method is disclosed for
obtaining dynamometer information (110) related to pumpjacks (10).
For this purpose, a change of pivotal direction of the walking beam
(18) may be detected by processor (82) utilizing an encoder
component (60) with spaced slots (64) therein and light signal
devices (68, 70, 72, 74) positioned to have a spacing different
from that of the spacing of the slots (64). Software techniques
filter out effects of stray mechanical vibrations. An infrared
transceiver (46, 50, 100) of a preferred embodiment includes a
radio frequency carrier generator (90) and modulator (88) that
produces an infrared signal receivable by a low cost consumer radio
receiver. The radio frequency modulation technique for infrared
signals (96) and related filtering (98, 102, 104) condition
formatted infrared signals for utilization in daylight and through
a car window for drive-by downloading of data to second computer
(108). A sensor (163) may be substituted for the encoder. A sensor
(163) may include a moveable light interrupter, such as a ball
(160) or a bubble (260), moveably disposed within the sensor. The
sensor may also provide one or more apertures (180) for
transmitting light through the apertures.
Inventors: |
Mills, Manuel D.; (Midland,
TX) |
Correspondence
Address: |
Loren G. Helmreich
BROWNING BUSHMAN
5718 Westheimer, Ste. 1800
Houston
TX
77057
US
|
Family ID: |
46257353 |
Appl. No.: |
09/747831 |
Filed: |
December 22, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09747831 |
Dec 22, 2000 |
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09369792 |
Aug 6, 1999 |
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6176682 |
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Current U.S.
Class: |
417/18 ;
417/12 |
Current CPC
Class: |
F04B 47/022 20130101;
F04B 49/065 20130101; E21B 47/007 20200501; E21B 47/009
20200501 |
Class at
Publication: |
417/18 ;
417/12 |
International
Class: |
F04B 049/00 |
Claims
What is claimed is:
1. A dynamometer readout apparatus for a pumpjack with a walking
beam, said walking beam being pivotally moveable in a first pivotal
direction and in an opposite second pivotal direction, said walking
beam changing pivotal direction twice during each pumping cycle for
pumping a well, said apparatus comprising: an encoder component
pivotally secured to said walking beam, said encoder component
having a plurality of spaced apart slots disposed therein, said
encoder being biased to remain at a reference orientation relative
to said walking beam; first and second light emitters with
corresponding first and second light detectors respectively aligned
on opposing sides of said encoder component, said first and second
light emitters and corresponding first and second light detectors
being fixed to said walking beam for angular movement in said first
and second pivotal directions with respect to said reference
orientation of said encoder component, said first and second light
emitters and corresponding first and second light detectors being
mounted with a spacing different than said spaced apart slots of
said encoder component to thereby produce a first sequence of
signals for movement of said walking beam in said first pivotal
direction and a second sequence of signals for movement of said
walking beam in said second pivotal direction; a load sensor
mounted to detect loading corresponding to said pumping cycle for
producing an electrical load signal; and a processor electrically
connected to said first and second light detectors to receive said
first sequence of signals and said second sequence of signals, said
processor analyzing said first sequence of signals and said second
sequence of signals to detect a change in direction from said first
pivotal direction of said walking beam to said second pivotal
direction of said walking beam, said processor using said change in
direction to control initiation of sampling of said electrical load
signal.
2. The dynamometer readout of claim 1, wherein said processor
distinguishes a mechanical jitter that produces a temporary change
from said first sequence of signals to said second sequence of
signals.
3. The dynamometer readout of claim 1, further comprising: said
processor obtaining a first time duration for a first pumping
cycle, said processor obtaining a predetermined number of samples,
said processor using said first time duration and said
predetermined number of samples to determine a sample rate for
sampling said electrical load signal during a second pumping cycle
subsequent to said first pumping cycle.
4. The dynamometer readout of claim 1, further comprising: said
processor selectively providing a sampling rate that varies during
each pumping cycle.
5. The dynamometer readout of claim 1, further comprising: a light
emitting transmitter, said processor outputting data at a constant
rate using a data format with an index word for beginning each new
dynamometer card.
6. The dynamometer readout of claim 1, further comprising: a radio
frequency carrier generator, a radio modulator receiving said
sampling from said processor and modulating said radio frequency
carrier generator to produce a modulated radio frequency carrier
signal, and a light emitting element to produce a light signal in
response to said modulated radio frequency carrier signal.
7. A method for providing a pumpjack dynamometer readout, said
pumpjack having a walking beam, said walking beam being pivotally
moveable in a first pivotal direction and in an opposite second
pivotal direction, said walking beam changing pivotal direction
twice during each pumping cycle for pumping a well, said method
comprising: providing a load sensor to detect loading corresponding
to each said pumping cycle for producing an electrical load signal;
producing a detection signal when said walking beam changes from
said first pivotal direction to said opposite second pivotal
direction during each said pumping cycle; determining a first
duration of a first pumping cycle from said detection signal;
selecting a designated number of samples of said electrical load
signal; determining a second cycle sample rate of said electrical
load signal for a second pumping cycle based on said designated
number of samples and said first duration of said first pumping
cycle, said second pumping cycle being subsequent to said first
pumping cycle; and sampling said electrical load signal for said
second pumping cycle at said second cycle sampling rate.
8. The method of claim 7, further comprising: determining a second
time duration of the second pumping cycle from the detection
signal, determining a third cycle sample rate based on the
designated number of samples and the second time duration, and
sampling the electrical load signal for the third pumping cycle at
the third cycle sample rate.
9. The method of claim 7, further comprising: providing that said
second cycle sampling rate is constant throughout the second
pumping cycle, and providing that the third cycle sampling rate is
constant throughout the third pumping cycle, the second cycle
sampling rate being changeable with respect to the third sampling
rate.
10. The method of claim 7, further comprising: providing that said
second cycle sampling rate selectively varies during said second
pumping cycle.
11. The method of claim 7, further comprising: providing that said
second cycle sampling rate varies during said second pumping cycle
based on a table stored in a memory.
12. A dynamometer readout for a pumpjack with a walking beam, said
walking beam being pivotally moveable along a beam length in a
clockwise pivotal direction and in an opposite counterclockwise
pivotal direction, the walking beam changing pivotal direction
twice during each pumping cycle for pumping a well, the apparatus
comprising: a pivotal position sensor secured to the walking beam,
the pivotal position sensor having apertures capable of
transmitting light through the aperture, the pivotal position
sensor including a chamber having an uninterrupted surface along a
length of the walking beam and a light interrupter positioned
within the chamber and moveably responsive to pivotal inclination
of the walking beam; first and second light emitters each mounted
on a side of the pivotal position sensor with a spacing along a
length of the walking beam between the first and second light
emitters, the first and second light emitters each being fixed to
the walking beam for angular movement in the clockwise and
counterclockwise pivotal directions with the walking beam; first
and second light detectors each mounted on another side of the
pivotal position sensor opposite a respective emitter with a
spacing along a length of the walking beam between the first and
second light detectors, the first and second light detectors each
being fixed to the walking beam for angular movement in the
clockwise and counterclockwise pivotal directions with the walking
beam, the first and second light detectors for generating a
clockwise sequence of signals corresponding to first and second
time periods when the walking beam is at first and second pivotal
positions, respectively, during movement of the walking beam in the
clockwise pivotal direction and for generating a counterclockwise
sequence of signals corresponding to third and fourth time periods
when the walking beam is at third and fourth pivotal positions,
respectively, during movement of the walking beam in the
counterclockwise pivotal direction; a load sensor to sense varying
loads on the walking beam during the pumping cycle and producing a
varying load signal representative of the sensed load; and a
processor responsive to each of the clockwise sequence of signals,
the counterclockwise sequence of signals, and the varying load
signal to generate dynamometer signals representative of varying
load as a function of pivotal position relationship of the walking
beam.
13. The dynamometer readout apparatus as defined in claim 12,
wherein the light interrupter further comprises: a gas bubble in a
liquid filled chamber in the pivotal position sensor.
14. The dynamometer readout apparatus as defined in claim 12,
wherein the light interrupter further comprises: a solid object in
a chamber in the pivotal position sensor.
15. The dynamometer readout apparatus as defined in claim 14,
wherein the solid object is a substantially spherical ball and the
uninterrupted surface is a floor, the ball moveable along the
floor.
16. The dynamometer readout apparatus as defined in claim 14,
wherein the processor determines a change in pivotal walking beam
direction and controls initiation of sampling of the varying load
signal from the load sensor at lest partially based upon the change
in pivotal direction.
17. The dynamometer readout apparatus as defined in claim 12,
further comprising: third and fourth light emitters each mounted on
a side of the pivotal position sensor with a spacing along a length
of the walking beam between the third and fourth light emitters,
the third and fourth light emitters each being fixed to the walking
beam for angular movement in the clockwise and counterclockwise
pivotal directions with the walking beam; and third and fourth
light detectors each mounted on another side of the pivotal
position sensor opposite a respective emitter with a spacing along
a length of the walking beam between the third and fourth light
detectors, the third and fourth light detectors each being fixed to
the walking beam for angular movement in the clockwise and
counterclockwise pivotal directions with the walking beam, the
third and fourth light detectors for generating a clockwise
sequence of signals corresponding to first and second time periods
when the walking beam is at fifth and sixth pivotal positions,
respectively, during movement of the walking beam in the clockwise
pivotal direction and for generating a counterclockwise sequence of
signals corresponding to third and fourth time periods when the
walking beam is at seventh and eighth pivotal positions,
respectively, during movement of the walking beam in the
counterclockwise pivotal direction.
18. The dynamometer readout apparatus as defined in claim 12,
wherein each of the first and second light emitters are on a same
first side of the sensor, and each of the first and second light
detectors are on a same second side of the sensor, opposite the
first side.
19. A method of providing a pumpjack dynamometer readout, the
pumpjack having a walking beam, the walking beam being pivotally
moveable in a clockwise pivotal direction and in an opposite
counterclockwise pivotal direction, the walking beam changing
pivotal direction twice during each pumping cycle for pumping a
well, the method comprising: securing a pivotal position sensor to
the walking beam, the sensor including a light interrupter movably
disposed within the pivotal position sensor; directing light from a
plurality of light emitters through apertures in the pivotal
position sensor; sensing the light from the plurality of light
emitters through the apertures by a respective plurality of light
detectors to generate a clockwise sequence of signals corresponding
to a plurality of time periods when the walking beam is at a
respective plurality of positions during movement in the clockwise
pivotal direction, and to generate a counterclockwise sequence of
signals corresponding to a plurality of time periods when the
walking beam is at a respective plurality of positions during
movement in the counterclockwise pivot direction; interrupting the
light received by a detector with a light interrupter movably
disposed within the pivotal position sensor and movable in response
to walking beam pivotal position; and sensing a load and producing
an varying load signal representative of the load on the walking
beam during the pumping cycle.
20. The method of providing a pumpjack dynamometer readout as
defined in claim 19, further comprising: sampling the sensed
varying load signal by the processor during at least one pumping
cycle with initiation of sampling and termination of sampling
during the pumping cycle based on a determined change from the
clockwise sequence of signals to the counterclockwise sequence of
signals and a determined change from the counterclockwise sequence
of signals to the clockwise sequence of signals.
21. The method of providing a pumpjack dynamometer readout as
defined in claim 19, further comprising: positioning a bubble in a
liquid filled chamber in the pivotal position sensor as the light
interrupter to provide the clockwise sequence of electrical signals
when the walking beam moves in the clockwise pivotal direction and
the counterclockwise sequence of signals when the walking beam
moves in a counterclockwise pivotal direction.
22. The method of providing a pumpjack dynamometer readout as
defined in claim 19, further comprising: positioning a solid light
interrupter in a chamber in the pivotal position sensor as the
light interrupter to facilitate generation of the clockwise
sequence of signals when the walking beam moves in the clockwise
pivotal direction and to facilitate generation of the
counterclockwise sequence of signals when the walking beam moves in
a counterclockwise pivotal direction.
23. The method of providing a pumpjack dynamometer readout as
defined in claim 22, wherein the solid light interrupter moves
within the chamber by rolling along an uninterrupted surface.
Description
1. FIELD OF THE INVENTION
[0001] The present invention generally relates to pumpjack
dynamometers and, more particularly, to apparatus and methods for
producing and transmitting dynamometer card information.
2. BACKGROUND OF THE INVENTION
[0002] Dynamometers are commonly utilized in the oil field to
monitor the operation of pumpjacks used to pump oil to the surface.
The dynamometer card provides information related to pumping
conditions as described in detail in subsequently listed patents.
For instance, a typical use of such information involves
determining when a well has reached what is known as a "pump-off"
condition wherein the wellbore does not receive enough oil to fill
the downhole pump during the entire pump stroke. Changes in the
dynamometer card readings over time may be used to provide this
information. It may be desirable to temporarily stop operating the
pump until the pump off condition has been obviated by continued
flow from the formation into the wellbore while the pump is shut
down. Pump-off control techniques are known to improve field
development efficiency and reduce maintenance costs.
[0003] Changes in the dynamometer card readings over time is one of
the more important uses of dynamometer card information.
Consistency over time in the way measurements are taken is
important for this use of dynamometer card information. Consistency
requires that calibrations remain constant and do not change over
time, as has been a problem with many prior art devices. It would
be desirable to have a sensor that does not require time consuming
initial calibration procedures, that automatically calibrates
itself, and that continuously re-calibrates itself so that one can
be assured that changes in dynamometer card information over time
are due to changes in the well rather than changes in the
calibrations.
[0004] Various sensors are provided in the prior art for
determining the position of the walking beam of the pumpjack.
Potentiometers, reed switches, and other types of switches have
been used in the past in order to supply signals indicative of the
position of the walking beam. The problem with such position
sensing devices is that they are usually subject to wear, require
careful initial calibration, require maintenance including regular
re-calibrations, and may not always provide accurate or reliable
information. Hydrogen sulfide gas is often present in the vicinity
of the pump jack, and that gas adversely affects the reliability of
much of this sensing equipment. Well personnel working on the
pumpjack may inadvertently loosen or change components in such a
way that calibrations are affected. Prior art equipment for sensing
the position of a walking beam is frequently mounted on the walking
beam at a location where it is highly susceptible to weather
conditions such as variable temperature, and may have reduced
reliability due to temperature drift errors. Minor irregularities
or mechanical jitters in movement of the walking beam may also
cause spurious or repeatable errors.
[0005] As the dynamometer data is produced, various means are used
to collect and use the data, some of which require expensive
sensors, some of which may be less reliable over time, and some of
which may require significant maintenance for calibration
requirements. It would be desirable to provide methods for sampling
dynamometer card information that may be used to monitor well
conditions over time at less cost with improved reliability.
[0006] Once data is collected, radio transmitters have been used in
the past to transmit the data to another location. However in some
areas, use of radio transmitters is not allowed. Where radio
transmitters are allowed, it is often difficult to obtain
additional channels for transmission. As well, FCC rules must be
followed and may require radio transmitters to be installed
according to certain specifications that may limit their usefulness
for some purposes. Infrared transmitters have limited usefulness in
sunlight due to ambient infrared noise that results in a short
transmission distance if operation is possible at all. As well,
infrared transmitters have limited selectivity and would have
problems for use with closely spaced wells where multiple
transmissions may occur.
[0007] The following patents discuss the aforementioned background
and problems in some depth along with previous solutions to the
many problems encountered in this area:
[0008] U.S. Pat. No. 4,363,605, issued Dec. 14, 1982, to Manuel D.
Mills, discloses an apparatus for generating an electrical signal
which is proportional to the tension in a bridle that supports a
string of sucker rod associated with a pumpjack unit.
[0009] U.S. Pat. No. 5,458,466, issued Oct. 17, 1995, to Manuel D.
Mills, discloses an apparatus and method for minimizing fluid
pounding in a pumpjack by dictating the length of the run cycles of
the pumpjack.
[0010] U.S. Pat. No. 4,631,954, issued Dec. 30, 1986, to Manuel D.
Mills, discloses an improved pump control having a device for
measuring relative movement between structural components of a
pumpjack, and converting the movement into a signal which varies
according to the magnitude of the movement.
[0011] U.S. Pat. No. 4,873,635, issued Oct. 10, 1989, to Manuel D.
Mills, discloses a pump off control device for controlling a
pumpjack unit. The device measures the length of time required for
the pump to down-stroke successive numbers of times. When the time
differential reaches a predetermined value, the well is shut in for
a time interval.
[0012] U.S. Pat. No. 4,492,029, issued Jan. 8, 1985, to Tanaka et
al., discloses an inclinometer comprising a sector weight pivotally
supported on a main body, which may become inclined. The weight is
relatively rotatable with respect to the main body and constantly
hanging vertically due to gravity regardless of an inclination of
the main body. A code part and a detecting part produces a
detection output based on the predetermined code according to the
inclination of the angle of the body.
[0013] U.S. Pat. No. 4,584,778, issued Apr. 19, 1986, to Komasaku
et al., discloses an angle change indicator comprising a pair of
opposing magnets, a sector-shaped pendulum made of an
electro-conductive non-magnetic material and pivotal past a spacing
between the opposing magnets, and a pair of photo sensors disposed
on both side edges of the pendulum.
[0014] U.S. Pat. No. 4,467,527, issued Aug. 28, 1984, to North et
al. discloses a digital level that includes a digital display for
displaying the angle of inclination between a straight edge of a
digital level and a desired reference plane. An alarm is also
included to indicate whenever the digital level is held parallel to
a desired reference plane.
[0015] U.S. Pat. No. 4,716,534, issued Dec. 29, 1987, to Baucom et
al., discloses an angle finder with a rotatably mounted disc on
which is mounted a weight. The disc has markings that represent two
degrees of arc. Three photo detectors sense the movement of the
markings and a microprocessor determines angular alignment of the
reference surface.
[0016] U.S. Pat. No. 4,798,087, issued Jan. 17, 1989, to Takeda et
al., discloses an inclination detector of a generally fan shaped
detector having a plurality of slits formed therein concentrically
at intervals, and a light emitting element and a light sensitive
element constituting a photo coupler disposed on opposite sides of
the displacement detection plate.
[0017] U.S. Pat. No. 4,811,492, issued Mar. 14, 1989, to Kakuta et
al., discloses a cant angle sensor assembly that includes a
pendulum pivoted on a supporting system adapted to be mounted on an
object whose cant angle is to be sensed for swinging movement in a
direction of the tilt of the object. A moveable electrode is
provided on the pendulum and has a first and second movable
electrode plate, and a first stationary electrode plate is fixedly
mounted on the supporting system in an opposed relation.
[0018] U.S. Pat. No. 4,922,620, issued May 8, 1990, to E. Terragni,
discloses a device for determining the inclination of a plane with
respect to a theoretical horizontal plane wherein an inclination
detector element is rotatably associated with a box like body.
Light detectors determine the position of the detector element with
respect to the base plane based on coded slits therein.
[0019] U.S. Pat. No. 4,942,668, issued Jul. 24, 1990, to R. C.
Franklin, discloses a digital inclinometer for detecting the
angular orientation of a structure that includes a rotatable
encoding disk on which is mounted a horizontal tilt sensor. The
inclinometer electronically measures, by angular indices on the
encoding disk, the difference between the angular orientation of
the device and a horizontal orientation.
[0020] U.S. Pat. No. 4,606,133, issued Aug. 19, 1986, to F. J.
Mills, discloses an inclinometer for producing high-resolution
signals of inclination relative to various references.
High-resolution data signals are produced through the use of a
digital encoding wheel, which is suspended in equilibrium in a
fluid to substantially eliminate frictional forces. A
microprocessor or state logic machine is used to analyze and
process the data to provide various displays of inclination
including an audible output.
[0021] U.S. Pat. No. 3,951,209, issued Apr. 20, 1976, to S. G.
Gibbs, discloses a method for monitoring a rod pumped well and
determining when the well has pumped off. The method uses a
dynamometer to monitor the power input to the rod string and senses
when the power input decreases to determine when the well pumps
off.
[0022] U.S. Pat. No. 4,143,546, issued Mar. 13, 1979, to R. P.
Wiener, discloses a device to determine the work done by a sucker
rod pump using a pendulum potentiometer mounted on the walking beam
of the pump and a load sensing pin located at the lower end of the
wire line which is suspended from the horsehead. Meters mounted in
a portable reading instrument show the maximum rod pull, the
minimum rod pull, the stroke of the pump, and the area of the
force-versus-stroke diagram. A display of the shape of the
force-versus-stroke diagram may be given through the use of an X-Y
plotter.
[0023] U.S. Pat. No. 4,483,188, issued Nov. 20, 1984, to McTamaney
et al., discloses an apparatus for recording and subsequent
playback of selected dynagraphs for well employing sucker rod
pumping units to determine well faults which cause well shut down.
Calibration data from well monitoring equipment is stored in a
first endless tape type of memory during calibration of the well,
and operation data from the monitoring equipment is stored in a
second endless tape.
[0024] U.S. Pat. No. 4,509,901, issued Apr. 9, 1985, to McTamaney
et al., discloses a method for detecting problems in sucker rod
well pumps and for determining which type of problem occurs. A
first transducer provides a signal representative of the load on a
sucker rod string and a second transducer provides a signal
representative of the sucker rod position. The load signal and
position signal are used to generate a dynagraph of rod load versus
rod position with the pump working normally.
[0025] U.S. Pat. No. 4,551,730, issued Nov. 5, 1985, to McTamaney
et al., discloses a method for entering control points relative to
a dynagraph of a well pumping unit using the position of a beam and
pen holder of an X-Y plotter.
[0026] U.S. Pat. No. 4,561,299, issued Dec. 31, 1985, to Orlando et
al., discloses an apparatus for detecting changes in inclination
used to determine the position of the sucker rod of a sucker rod
pump and includes a magnetic field sensor such as a linear output
transducer to provide a linear output signal and a cantilever
spring having a counterweight and magnet on its free end disposed
adjacent to the linear transducer.
[0027] U.S. Pat. No. 4,583,915, issued Apr. 22, 1986, to Montgomery
et al., discloses a pump off controller that checks for pump off by
calculating the area inside of a figure whose boundaries are the
minimum load.
[0028] U.S. Pat. No. 4,594,665, issued Jun. 10, 1986, to Chandra et
al., discloses an apparatus for detecting fluid found in a sucker
rod oil well, using values of sucker rod position and sucker rod
load to calculate a reference position and a selected load
value.
[0029] U.S. Pat. No. 4,817,049, issued Mar. 28, 1989, to Bates et
al., discloses a data logging device with a data memory unit and a
transducer interface unit.
[0030] U.S. Pat. No. 4,973,226, issued Nov. 27, 1990, to F. E.
McKee, discloses a method of maintaining a substantially constant
amount of filling of a liquid well pump actuated by a polished rod
which is reciprocated by a prime mover.
[0031] U.S. Pat. No. 5,064,349, issued Nov. 12, 1991, to Turner et
al., discloses a method of monitoring and controlling a pumped well
having a rod string extending from a pumping unit.
[0032] U.S. Pat. No. 5,167,490, issued Dec. 1, 1982, to McKee et
al., discloses a method of calibrating a well pump off controller
for determining the average load during a pumping stroke.
[0033] U.S. Pat. No. 5,182,946, issued Feb. 2, 1993, to Boughner et
al., discloses a device for use on a well pumping unit that
provides for real time measurement and recording of acceleration of
a polished rod resulting from the oscillating linear motion induced
by the rotating motion of the pumping unit crank.
[0034] U.S. Pat. No. 5,224,834, issued Jul. 6, 1993, to Westerman
et al., discloses an apparatus for controlling the operation of a
rod pumped well.
[0035] U.S. Pat. No. 54,291,777, issued Mar. 8, 1994, to Chang et
al., discloses a system for monitoring performance of a pumping
unit of an oil well that includes a first sensor for measuring the
inclination angle of a beam forming part of the pumping unit, a
second sensor for measuring the load on the beam, and a third
sensor for measuring the load on an electrical motor used in
conjunction with the pumping unit.
[0036] U.S. Pat. No. 5,406,482, issued Apr. 11, 1995, to McCoy et
al., discloses a device to produce a position trace for a pumpjack
with stroke markers to indicate position of the rod during its
cyclical operation using an accelerometer.
[0037] U.S. Pat. No. 4,541,274, issued Sep. 17, 1985, to J. C.
Purcupile, discloses a device wherein pulses produced by a pulse
generator coupled to the output shaft of an electric motor are
counted by a computer to locate the polish rod at a series of
positions during each reciprocation.
[0038] Although the above-listed patents address problems relating
to position indicating sensors, they do not disclose highly
reliable techniques for automatic calibration and re-calibration of
such devices to thereby substantially eliminate calibration errors
that may otherwise distort dynamometer cards taken at different
times using prior art devices. The present device also works to
reduce or eliminate errors caused by mechanical jitter or
variations in the walking beam movement through the pumping cycle.
As well, the present invention provides apparatus and techniques to
improve data collection techniques. Moreover, the present invention
provides reduced manufacturing and operating costs.
[0039] Consequently, there remains a need for a lower cost, readily
available, easily manufactured, quickly assembled, lower
maintenance apparatus and methods for providing data used for
producing dynamometer cards. Those skilled in the art have long
sought and will appreciate the present invention that addresses
these and other problems.
3. SUMMARY OF INVENTION
[0040] In accordance with the present invention, a dynamometer
readout apparatus is provided for a pumpjack. The pumpjack has a
walking beam which is pivotally moveable in a first pivotal
direction and in an opposite second pivotal direction. The walking
beam changes pivotal direction twice during each pumping cycle for
a pumping well. An encoder component may be pivotally secured to
the walking beam and has a plurality of spaced apart slots disposed
therein. The encoder component may be equipped with a biasing
member for biasing the encoder component to remain at a
substantially constant reference orientation as compared to the
walking beam. Aligned on opposite sides of the encoder component
may be first and second light emitters with corresponding first and
second light detectors which are fixed in position to the walking
beam for angular movement in the first and second pivotal
directions with respect to the reference orientation of the encoder
component. These first and second light emitters and corresponding
light detectors are mounted with a spacing different than the
spaced apart slots of the encoder component to thereby produce a
plurality of electrical signals. The electrical signals include a
first sequence of signals for movement of the walking beam in the
first pivotal direction and a second sequence of signals for
movement of the walking beam in the second pivotal direction.
[0041] The dynamometer apparatus further comprises a load sensor,
which may be mounted to detect loading corresponding to the pumping
cycle for producing an electrical load signal. A processor is
electrically connected to the first and second light detectors to
receive the first sequence of signals and the second sequence of
signals. This processor may be programmed to analyze the first and
second sequences of signals to detect a change in direction from
the first pivotal direction of the walking beam to the second
pivotal direction of the walking beam. The processor may also be
preferably programmed to distinguish any mechanical jitter that
produces a temporary change from the first to second sequences of
signals. The processor may time from an initial change of the first
to second sequences of signals and continues to monitor to verify
that the second sequence of signals is consistent. This process
verifies that a change in direction from the first to the second
pivotal direction of the walking beam has occurred. The processor
may also be programmed to time the pumping cycle and set a window
period wherein a change from first to the second pivotal direction
of the walking beam is projected to occur. The processor uses the
change in direction to control the initiation of sampling of the
electrical load signal for producing dynamometer readout of load
with respect to the pumping cycle.
[0042] The processor may provide a sampling rate that is variable
for each pumping cycle, depending on the duration of the pumping
cycle. In doing so, the processor may obtain a first time duration
for the first pumping cycle and a predetermined number of samples.
The processor uses the first time duration and predetermined number
of samples to determine a sample rate for sampling the electrical
load signal during the second pumping cycle subsequent to the first
pumping cycle. The processor thus may do the same to each
subsequent pumping cycle. The processor may therefore provide a
first constant sampling rate during the first pumping cycle and a
second constant sampling rate during the second pumping cycle, etc.
The sampling rate may also vary during each pumping cycle according
to a table or as desired.
[0043] For transmission purposes, the sampled data may be
transmitted at a fixed rate that is approximately half of a time
duration required for a fast pumping unit to complete the pumping
cycle. By spacing each sample of sampled data throughout a pumping
cycle transmission signal with a data separation indicator
therebetween, each sample is separately distinguishable as is
desirable for transmission accuracy purposes.
[0044] The processor transmits data at a constant rate using a data
format with an index word for beginning each new dynamometer card.
Data is transmitted from a light-emitting transmitter on the
dynamometer readout device.
[0045] The dynamometer readout may also comprise a radio frequency
carrier generator and a radio modulator for receiving the sampled
data from the processor and for modulating the radio frequency
carrier generator to produce a modulated radio frequency carrier
signal. A light emitting element may be used as a transmitter to
produce a light signal in response to the modulated radio frequency
carrier signal. For receipt of the light signal, a light filter may
be used for filtering the light signal and another light detector
receives the light signal. The light detector produces the
modulated signal and a radio frequency detector demodulates the
modulated signal to produce the sampled signal. A second computer
may receive and analyze the sampled signal. This second computer
may be operable for producing a dynamometer card from the sampled
signal. The dynamometer receiver preferably uses a narrow band
filter for filtering the output of the light detector and a high
gain amplifier for amplifying an output of the narrow band
filter.
[0046] Other varieties of sensors may be substituted for the
slotted encoder component. A dynamometer readout may include a
sensor having one or more apertures through which light is
projected from a light emitter to a light detector. A moveable
object that may distort or block the light, such as a solid object
or a gas or fluid bubble, may be provided within the sensor. The
moveable object may be positioned to move along a path that
intersects the light path through the aperture. The moveable object
may act as a light interrupter to interrupt the light received by
various sensors as the interrupter moves in response to walking
beam movement. Such embodiments may include two or more pairs of
light emitters and detectors.
[0047] It is an object of the present invention to provide an
improved dynamometer readout device and method.
[0048] It is another object of the present invention to provide a
highly reliable device whereby long term calibration errors are at
least substantially eliminated so that the dynamometer card changes
over time are indicative of changes in the well rather than changes
in calibration.
[0049] It is yet another object of the present invention to provide
an improved data sampling method.
[0050] It is yet another object to provide an improved data
transmission device and method.
[0051] These and additional objects, features, and advantages of
the present invention will be apparent to those skilled in the art
especially after review of the technical drawings, the descriptions
and discussions given herein, as well as the appended claims. It
will be understood that listed objects, features, and advantages of
the present invention are provided solely as an aid for more
quickly understanding aspects of the invention and are not intended
to be limiting of the invention in any way.
4. BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 is a diagrammatical side elevational view of a
pumpjack unit having apparatus made in accordance with the present
invention associated therewith;
[0053] FIG. 2 is a diagrammatical view of a pumping cycle sensor
for a pumpjack in accord with the present invention;
[0054] FIG. 3 is an elevational view of a slotted component for use
with the pumping cycle sensor of FIG. 2.
[0055] FIG. 4 is a block diagram of a light transmission and
receiving system for sending dynamometer card information in accord
with the present invention; and
[0056] FIG. 5 is an elevational view of a suitable transceiver for
receiving dynamometer card information in accord with the present
invention.
[0057] FIG. 6 is a diagrammatical view of a dynamometer readout
apparatus including a solid sphere moveably disposed within a
sensor body.
[0058] FIG. 7 is a diagrammatical view of a dynamometer readout
apparatus including a fluid bubble moveably disposed within a
sensor body.
[0059] While the present invention will be described in connection
with presently preferred embodiments such as those described in the
above-designated figures, it will be understood that it is not
intended to limit the invention to those embodiments. On the
contrary, it is intended to cover all alternatives, modifications,
and equivalents included within the spirit of the invention and as
defined in the appended claims.
5. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0060] Referring now to the drawings, and more particularly to FIG.
1, a pumpjack unit 10 is shown in operative relationship respective
to a wellhead 12. A downhole pump (not shown) is activated by
reciprocal movement of sucker rod string (not shown) and polished
rod 14 that is suspended from horse head 16. Horse head 16 is
affixed to walking beam 18, which is a rigid beam that extends on
either side of pivot connection 20. Walking beam 18 is reciprocated
by a prime mover 22, which may typically comprise an electric
motor. Prime mover 22 drives walking beam 18 through a drive system
which may typically comprise elements such as drive belt 24, crank
arm 26, drive arm 28 that is pivotally connected to walking beam 18
and crank arm 26 with pin connections 30 and 32. Walking beam 18 is
pivotally supported by a suitable frame 34 such that walking beam
pivots in two different directions, moving sucker rod string and
polished rod 14 upwardly and downwardly during each pump
stroke.
[0061] A load transducer of some desired type, such as strain gauge
36, is mounted with clamps 38 or other means to a convenient
protected position on walking beam 18. The purpose of strain gauge
36 is to measure the load changes on the walking beam as it is
driven by prime mover 22 during the pumping cycle. The load changes
are proportional to the load changes on sucker rod string as
indicated at polished rod 14 utilized at the surface to effect a
seal. The load transducer is of the type that produces an
electrical signal in response to changes in loading on walking beam
18. This may be an electrical bridge type transducer or the like.
It is to be understood that other types of load transducers may be
employed and at other locations. For instance, transducers may
include a polished rod load cell 40 or other transducers secured to
the horse head, cables, polished rod, and the like. To provide
dynamometer information, it is therefore necessary to obtain
loading information during each pumping cycle.
[0062] Micro-controller 42 is mounted for movement with walking
beam 18 and is shown diagrammatically in FIG. 2. Micro-controller
42 receives the data from load sensor 36 and from a preferably
internally mounted positioning sensor. Micro-controller 42 and
preferred components are discussed in more detail hereinafter.
[0063] Cable 44 from micro-controller 42 is preferably a four
conductor type of cable and connects to infrared transceiver 46.
Transceiver 46 may include, if desired, a twelve volt power supply
plug 48 as an alternative, backup, or main means to power the
dynamometer readout of the present invention. An infrared
transceiver unit 50 is also preferably used as discussed in more
detail subsequently.
[0064] Micro-controller 42 also preferably includes a means for
monitoring the oscillatory movement involved in a reciprocal
pumping cycle. During a pumping cycle, walking beam 18 rotates,
tilts, or pivots in one direction and then in the opposite
direction during which time the sucker rod, polished rod 14, and
the like go upwardly and downwardly. Generally, a dynamometer card
is a graph that will show the upper and lower points of the pumping
cycle on either end thereof. The beginning of a pump stroke may be
arbitrarily defined as either the top or the bottom of the pumping
cycle. The micro-controller times, preferably to the millisecond,
the elapsed time between the beginning of one stroke and the
beginning of the next. Preferred points of interest are the top and
bottom of the stroke. These points occur at the end of the pivotal
direction of walking beam 18 and at the ends of movement of
polished rod 14. For this reason, most pump cycle sensors have to
be calibrated so as to be exactly in the desired position. It is
difficult to obtain and maintain the necessary accuracy to provide
accurate timing to the millisecond at the top and bottom of the
stroke as desired with prior art pump cycle sensors.
[0065] One presently preferred embodiment of the present invention
uses a sensor that does not require calibrations, but rather
calibrates itself in a preferred method of operation of the sensor,
and preferably does so during each cycle so as remain extremely
accurate. Referring now to FIG. 2 and FIG. 3, there is shown a
encoder component 60 mounted for rotation within micro-controller
housing 62. Micro-controller housing 62 is preferably secured to
walking beam 18 at a convenient position. Encoder component 60 is
mounted on bearings or other suitable means as indicated at 63 to
allow free rotation of encoder component 60. Encoder component 60
should be free to rotate easily so as to detect changes in pivotal
direction of movement of walking beam 18. While encoder component
60 is shown in the form of a wheel, it could also take the shape of
a fan, wedge, or other shape so long as it functions as discussed
subsequently. Slots 64 are preferably identical and are preferably
arranged around the circumference of encoder component 60 at an
even spacing. With the wheel construction as shown, not all slots
will be used as walking beam 18 is limited in its tilt, and so some
slots could be left out as desired. However, with the wheel
construction as shown, a wide range of different pivotal amplitudes
of oscillation of walking beam 18 can be accommodated. Which slots
will be used and which slots will not be used actually depends on
the location of subsequently discussed components and the pivotal
amplitude of oscillation of the walking beam.
[0066] Preferably, several hundred identical slots 64 are provided
at even spaces around encoder component 60, and a convenient number
would be 360 slots with a one-degree spacing. As will be seen
subsequently, this spacing provides one-quarter degree accuracy
although it will be understood that the accuracy could be made
significantly greater by providing more slots. The working portion
of encoder component 60 could be made larger to accommodate more
slots, if desired, and non-working portions left off. Other
additional components of the type discussed subsequently could also
be used to improve accuracy, if desired.
[0067] To detect a change in direction, encoder component 60 is
preferably biased to remain in a constant position while walking
beam 18 moves pivotally. This may be accomplished in different
ways. For instance, weights 66 may be used in a position below the
center of rotation so as to bias encoder component 60 in a fixed
position. An open region 67 may be used for the same purpose. The
shape of encoder component 60 in a fan or wedge would result in a
weight biased to one position by gravity. Preferably, encoder
component 60 has a large thickness or weight to provide a resting
inertia that will overcome small frictional forces that might cause
gripping of encoder component 60 at end points of the stroke. Thus,
encoder component 60 is set up as a reference orientation in the
presently preferred embodiment. However, it will be understood that
encoder component 60 could conceivably be the component that moves
with walking beam 18.
[0068] In a preferred embodiment, light emitters 68 and 70 are used
with corresponding light detectors 72 and 74 to produce two
electrical signals as the light from light emitters 68 and 70 is
passed/prevented by slots 64 in encoder component 60. Light
emitters 68 and 70 and light detectors 72 and 74 may be light
emitting diodes and corresponding photo detectors which are
electronic components of low cost and wide availability with known
circuitry for operation such as power supplies 76 and other related
components.
[0069] Light elements 68-72 are preferably rigidly affixed to
housing 62 which is preferably affixed to walking beam 18 such that
housing 62 pivots exactly with walking beam 18.
[0070] The exact position of light elements 68-72 is not important
but the relative spacing between the light elements is important
for operation in the desired mode. For this operation, light
elements 68-72 do not have the same spacing as that of slots 64.
For instance, if slots 64 are spaced with one degree between them,
light emitter/light detector combination 68,72 would be spaced N
degrees plus some fraction of one degree from light emitter/light
detector combination 70, 74. As an example for the case where slots
64 have a one degree spacing, light emitter/light detector 68,72
might be spaced by ten degrees plus one-quarter degree or ten and
one-quarter degrees from light emitter/light detector 70, 74. Thus,
as encoder component 60 pivots with respect to light elements
68-72, two distinct electrical signals are produced at 78 and 80
and fed to micro-controller circuit board or boards 82.
Micro-controller board 82 may have a micro-controller, processor,
or computer, and the various associated power supplies, buffers,
memory and so forth for running a desired program or accomplishing
the desired tasks as discussed herein. A convenient preferred
differential spacing includes one quarter of the encoder slot
spacing as might be termed a "quadrature" spacing. However, it will
be understood that other differential spacings could be used as
discussed above so long as two distinct out of phase signals are
produced that can be used to determine not only relative movement
but also relative direction of the movement between encoder wheel
60 and light elements 68-72 in the manner discussed
subsequently.
[0071] Given the above description whereby each light detector 72,
74 produces a different signal for the reasons of spacing as
discussed above, and given that each light detector is designed to
produce either an on or off signal, characterized as a 1 or a 0,
then it will be understood that there are 2 or four possible
combinations of the signals or states. Moreover, the four signals
occur in a specific sequence that depends on the direction of
pivotal movement of relative motion between light detectors 72,74
and encoder component 60 or, more specifically, with the direction
of pivotal movement of walking beam 18. Table 1 describes the
movement in terms of these signals and shows the unique sequence
for the two different directions of movement. Assuming the slots
are at one degree intervals, the four states would occur each
degree of pivotal movement thereby giving rise to accuracy within a
one-quarter degree increment.
1 TABLE 1 Detector 72 Detector 74 Increments of Forward Movement 0
0 0 1 1 0 2 1 1 3 0 1 Increments of Reverse Movement 0 0 0 3 0 1 2
1 1 1 1 0
[0072] The above inputs form a sequence that would be seen by
micro-controller board 82 as repeating each four increments, which
in the present example would be every degree. Whenever the sequence
changes, the processor on micro-controller board 82 would know that
a potential change in direction of walking beam 18 has occurred.
Thus, there is no need to position micro-controller 42 in a precise
relationship and it automatically calibrates itself regardless of
the orientation. In a preferred embodiment, calibration effectively
occurs every pumping cycle so that the typical calibration types of
errors are reduced or eliminated.
[0073] It has been discovered that mechanical jitter from vibration
and the like may be picked up due to the sensitivity of this device
and may cause very short momentary reversals and therefore might be
interpreted as changes of direction if not for programming intended
to correct such problems. Such jitter typically occurs for only a
few intervals before the actual direction of pivotal movement
reasserts itself. Several methods exist for filtering out actual
changes in direction from temporary changes in direction. In one
method, microprocessor board 82 detects the sequence change and
initially assumes a change in direction has occurred. At this
point, which may be the beginning of the up-stroke or down-stroke,
the micro-processor begins sampling data such as the electrical
loading signal from strain gauge 36 as discussed in more detail
below just as if the apparent reversal is an actual signal. The
data is temporarily stored however, to verify that a change in
sequence has occurred. If the sequence remains constant for a
selected number of intervals, e.g., seven intervals, then the
computer assumes the change in sequence is real and outputs the
sampled data for transmission.
[0074] Another method for filtering out mechanical jitters and
vibrations may be used after the top and bottom stroke pattern have
already been established. The computer will look for a window
wherein it is anticipated that the next reversal will occur.
Generally, only a small time difference, if any, occurs in the time
duration of consecutive pumping cycles. Thus, mechanical jitters
that occur between cycles may be largely filtered out once a
pattern is established. In another method, the micro-processor
could be programmed to wait until a certain number of increments
has occurred in an opposite pivotal direction before beginning to
sample. So long as the amount of delay stays constant from cycle to
cycle, the history of change of the dynamometer cards will still be
quite visible and the detection of changes over time is in many
cases the intended use of the dynamometer card. In another method,
micro-processor 42 determines a rate of change of increments so
that jitters and mechanical vibration that occur at a rate of
change significantly different are subject to filtering. In another
embodiment, a general photo element may be used with a relatively
wide slot to detect a window wherein it is anticipated that a
change in direction may occur.
[0075] As discussed above, any mechanical sticking of encoder
component 60 itself may be reduced by increasing the bias force
and/or increasing the inertia of encoder component 60. This may be
accomplished with additional weights, reshaping to an elongate
element, improving the bearings, increasing the mass of the encoder
component, and other means, so that the disclosed presently
preferred configuration is not considered to be at all limiting of
these aspects. In another method, some means may be provided to
detect mechanical motion orthogonal to the first and second pivotal
directions thus indicating mechanical problems with pumpjack
10.
[0076] Thus, even with the highly sensitive readings derived from
the present invention that is capable of detecting small mechanical
jitters and vibrations, it is possible to obtain highly consistent
data gatherings. As discussed above, consistency of the
calibrations and readings over time is often the most important
aspect of the dynamometer cards when looking for changes in the
well over a time period is important. The elimination of slowly
changing errors and calibration errors results in an improved
product in an area where consistency is desired.
[0077] The dynamometer readout of the present invention also
includes an improved data sampling technique that is preferably
used with the highly accurate, automatically calibrated position
detector described above but could be used with other position
detectors such as mercury switches and the like.
[0078] At the beginning of a pumping cycle, which can arbitrarily
be defined as either the top or bottom of the stroke depending on
what is most convenient, micro-controller 42 times, preferably at
least to the millisecond, the elapsed time duration of the cycle up
to the beginning of the subsequent cycle. This time duration is
used to predict what the next or subsequent pumping cycle elapsed
time will be although in practice the actual time of the next
pumping cycle may vary slightly. The predicted time duration is
used with the number of samples, which the processor will attempt
to take in order to calculate the rate at which samples will be
taken. For instance, it might be desirable to take 360 samples, as
this number would correspond to each degree increment of the
pumping cycle. Knowing the predicted time interval for the cycle,
and the number of samples, micro-controller 42 is programmed to
calculate the sampling rate. The sampling rate could be constant
throughout the pumping cycle. However, it may be preferable to use
a dual modulus counting rate where one sampling rate is used for
the down-stroke and another is used for the up-stroke to get the
effect of fairly evenly spaced data samples throughout the stroke
interval. A table could be used for this purpose as well. In fact,
a table could optionally be placed in micro-controller 42 memory
for the geometry of the pumping unit to create data sample spacing
which is either evenly divided or which is intentionally not evenly
divided throughout the stroke interval. The intentionally unevenly
divided sampling rate, with respect to the stroke interval, could
be used to sample more heavily during certain critical parts of the
dynamometer card so that differences in the dynamometer cards over
time is more readily apparent.
[0079] It will be understood that the sampling rate is preferably
recalculated for each pump stroke to maintain accuracy. Therefore,
the time duration of a first pumping cycle would be used to
calculate the sampling rate for a second pumping cycle. The time
duration of the second pumping cycle would be used to calculate the
sampling rate of a third pumping cycles and so forth. It may be
that if the next pump stroke ends earlier than expected a small
number of samples may be left off. On the other hand, if the stroke
ends later than expected a small pause may occur. However, due to
the large number of samples being taken, this difference will be
negligible and could be made less negligible by taking more
samples. Probably somewhere in the range of 300 to 700 samples
would provide highly detailed information. This format produces a
low cost and consistent method of producing a dynamometer card that
may be more suitable for use than more complex sampling techniques
and devices. Time difference information between strokes as well as
the time duration of each stroke may also supply useful information
about a pump off condition and be sent along with other data.
[0080] Of course, if desired, the sampling rate could be controlled
from the pump cycle position detector discussed above wherein each
degree or half degree or so forth of the pumping cycle, as
determined from relative movement with respect to encoder component
60 could be used to precisely pinpoint the angle of the sample of
the pumping cycle with respect to the load. For instance, each
second or fourth state in the sequence of increments as discussed
earlier could be used to signal another load sample to be taken.
Samples that were missed or the like could be handled as discussed
below in dealing with the format of the data transmission and
device for data transmission in accord with the dynamometer readout
of the present invention.
[0081] Referring to FIG. 4 and FIG. 5, the basic components of an
infrared transceiver in accord with the present invention. The
preferred embodiment of this aspect of the dynamometer readout in
accord with the present invention uses relatively inexpensive radio
components that are already widely used in combination with an
infrared transceiver. While only a transmitter/receiver is shown in
FIG. 4, it will be understood that two sets of the
transmitter/receiver of FIG. 4 are used that are substantially the
same so that computer 108 of FIG. 5 and micro-controller 42 can
send and receive. Experiments with infrared data association (IRDA)
devices have shown they do not have the range or sufficient
immunity to high ambient light levels, such as bright sunlight, or
other interfering infrared sources. To overcome this problem, as
discussed below, instead of switching the infrared on and off
directly, a carrier frequency is used where the infrared diode is
switched at a radio carrier frequency, and the photodetector signal
at the receiving end is preferably filtered with a high Q narrow
band circuit and amplified to a high level. To further improve the
range, sensitivity, and selectivity, a radio receiver on a chip is
incorporated into the infrared receiver, which interfaces to a
portable computer.
[0082] Computer 86 of FIG. 4 may be a microprocessor, processor,
controller or the like preferably mounted on micro-controller board
82 of micro-controller 42. Cable 44 is used to supply a signal to
infrared transmitter 50 that preferably also includes a light
detector such as a photosensitive diode. Thus, computer 86 samples
the electrical load signal produced by strain gauge 36 and produces
a sampled data signal. That signal is preferably applied to
modulator 88, which may be in housing 62 of micro-controller 42 or
may be in the housing of transceiver 46 which is mounted in a fixed
relatively rigid position on frame 34. Modulator 88 operates with
mixer 92 to modulate radio frequency carrier oscillator signal 90.
The modulated signal is applied to photo diode 94 that is part of
infrared transmitter 50 of FIG. 1. The modulated light signal 96 is
produced and is transmitted through light filter 98 placed on
receiver 100 shown in FIG. 5. The light filter filters out all
ambient light except that at the desired wavelength to remove
noise. Photodetector 100 receives the modulated light signal.
Preferably, high Q narrow passband filter 102 is used to further
filter the signal to reduce noise. The filtered signal is applied
to high gain amplifier 104 and then applied to a readily available,
low cost, radio frequency detector 106 from which is extracted the
sampled data. The sampled data may then be applied to computer 108
through cable 112. Computer 108 may then be used to analyze the
dynamometer data and produce a dynamometer card or a longer term
comparison of several cards as indicated at computer screen
110.
[0083] The above-described device preferably uses proven techniques
of single or double conversion superheterodyne circuitry adapted
from ordinary radio devices and available at low costs. Radio
receiver detectors may be of the type that use frequency shift
keying of the modulated infrared carrier but could also use
amplitude shift keying. At this time, carrier frequencies in and
near the AM broadcast band are used. No RF is radiated so there is
no problem with radio communication interference. RF leakage is
well below FCC Part 15 limits. The circuit is preferably designed
to be insensitive to radiated or conducted RFI. However, almost any
carrier frequency that is within the turn on and turn off times of
the infrared diode and detector should be quite effective. The
infrared diodes and detectors should be as powerful as possible and
transmit a light wavelength that will preferably travel easily
through a car window for drive by data recording.
[0084] By incorporating the ability to tune the carrier via regular
radio techniques such as phase locked loops or direct digital
synthesis, another unique capability of this device is the ability
for more than one device to operate in close proximity with other
similar devices and to select at the receiving end which unit is to
be monitored such as one selects which radio station to listen to.
Thus, closely located wells may use different radio carrier
frequencies as desired. At frequencies below about 10 MHZ, ordinary
microprocessor grade crystals should provide sufficient accuracy to
have the received signal fall within the desired passband.
[0085] A range of from 10 meters to 30 meters may typically be
anticipated. To keep cost low, it is presently preferred to limit
data rates to the audio spectrum, that is about 10 to 20 KHz at the
upper end, primarily because ordinary consumer radio components may
then be used for demodulation of data. However, since channel
bandwidth is not limited to radio spectrum allocations, higher data
rates than 20 KHz may be utilized. A speed of 9600 baud should be
fast enough to get the data out without a buffer overrun in actual
use. It is anticipated that with ASIC chip design, a fully
integrated transceiver, transmitter, or receiver module could be
easily designed for applications far beyond the dynamometer readout
use outlined here.
[0086] During transmission of the signal, it is preferable that the
beginning of each new set of data be indicated or announced with an
index word. As an example, each time an index word is transmitted,
the receiving computer would then expect to receive 360 data words
assuming 360 samples of the load signal were to be transmitted.
With a receipt of the next index word, the receiving computer would
assume it has received all data for the previous dynamometer card
and would expect data for a subsequent dynamometer card.
[0087] Data is preferably sent at a rate fast enough so that all
words, such as 360 words, may be sent through the communications
channel for receipt by computer 108 in about one-half the time
required for the fastest known pumping units to complete a full
pumping cycle. The data is spaced out with nulls or other data
separator indicators, or an idle channel to fill in the gaps for
the slower moving units. In this way, the data rate for each
transmitter can be fixed, and the same micro-controller 42,
transceiver 46, and software may be mass produced for a wide
variety of pumping units without having to tweak the transmission
speed components.
[0088] The index word is preferably repeated at the beginning of
each new stroke (or dynamometer card) that is transmitted. This
technique and a null or other signal between data samples provides
a means to deal with the occasional missed data due to
interference, marginal infrared signal, etc. In this way, cards
corrupted by missing data may be quickly re-drawn and bad cards
either discarded or interpolated in software. It is anticipated
that with correction codes, errors may be further reduced and may
even be correctable.
[0089] Thus, the dynamometer readout of the present invention
provides for an improved device that, in one preferred embodiment,
uses an encoder wheel and appropriate software for automatic
calibration and continuous re-calibration. In this way, cards
produced over time may be used to make meaningful comparisons. Data
is sampled by a unique low cost method that does not require exact
correlation signals to be produced during the pump cycle associated
with the loading signal utilizing transducers that in the past have
been associated with wear. Moreover, an infrared transceiver may be
used in another preferred embodiment of the present invention to
allow drive by downloading of stand alone pump off controls and
other devices in an outdoor environment where it would be
inconvenient to physically get out of the vehicle and connect a
cable to the unit. It would be an excellent technique for hazardous
environments or those where costly regulations would be encountered
in making a physical connection.
[0090] In embodiments, such as illustrated in FIGS. 6 and 7, a
dynamometer readout for a pumpjack may include a microcomputer 86
and/or processor 42 which includes or is connected to a pivotal
position sensor 163 secured to the walking beam and having one or
more apertures 180 in the sensor 163 capable of transmitting light
to the sensor 163. The sensor 163 may be connected to the processor
42 or 86, electrically, optically or by radio. A light interrupter
160 or 260 may be included within the pivotal position sensor 163,
with the light interrupter 160 or 260 being moveably responsive to
changes in the inclination of the walking beam. The sensor may
include an uninterrupted surface 162 or 262, along which the light
interrupter, 160 or 260, may freely move. The uninterrupted surface
may include a floor, such as may be found in a round
cross-sectioned tube or housing, or a substantially surface such as
may be found in a quadratic cross-sectioned tube or housing.
[0091] In an embodiment as illustrated in FIG. 6, the light
interrupter 160 may be a solid object 160, such as a ball, a
cylinder, or a disk, moveably positioned within the sensor 163.
Sensor 163 may be filled with a liquid or a gas as desired,
depending upon obtaining a desired degree of attenuation of
interrupter velocity and/or acceleration. The sensor 163 may
include a substantially smooth, uninterrupted surface 162 along
which the light interrupter 160 may freely move in response to
changes in walking beam inclination. The solid object light
interrupter 160 may move along the substantially smooth,
uninterrupted surface, such as by rolling or sliding within the
chamber. The term uninterrupted surface, as used herein may be
defined to broadly encompass a tube, chamber, housing, or
substantially planar surface, which may substantially encase,
contain, or support the light interrupter. For example, the
uninterrupted surface may include a tube having a substantially
circular, rectangular or square cross-section.
[0092] In an embodiment as illustrated in FIG. 7, the light
interrupter 260 may be a bubble of a first fluid, such as air,
positioned within a chamber 163 including a second fluid, such as a
clear liquid, therein. Light may be refracted or interrupted at the
gas-liquid interface. The chamber 163 may include a substantially
smooth, uninterrupted surface 262 along which the bubble type light
interrupter may move in response to changes in walking beam
inclination. The bubble may also be a solid object, which floats or
may be otherwise suspended within a fluid. The fluid may be a fluid
resistive to freezing. The uninterrupted surface, as defined
previously, may also include a substantially clear tube, such as
may be commonly found in a carpenters level. The tube may be
substantially straight or may include a slight arc or curvature,
along the length of the tube.
[0093] In embodiments such as illustrated in FIGS. 6 and 7, the
first 168 and second 170 light emitters with corresponding first
172 and second 174 light detectors, respectively, each emitter may
be aligned on a side of the sensor 163 opposite the respective
emitter. Each of a plurality of emitters may be on the same side of
the sensor, and each of a plurality of detectors may be on the
opposing side of the sensor. The first 168 and second 170 light
emitters and the corresponding first 172 and second 174 light
detectors may be secured to the walking beam for angular movement
in the first and second pivotal directions. The first pivotal
position may be a clockwise pivotal direction, and the second
pivotal direction may be a counter-clockwise pivotal direction of
the walking beam. The first 168 and second 170 light emitters and
the corresponding first 172 and second 174 light detectors may be
mounted adjacent the sensor 163, with a spacing along the length of
the walking beam, between the first light emitter 168 and the
second light emitter 170. Thereby, a first or clockwise sequence of
signals corresponding to first and second time periods when the
walking beam is at first and second pivotal positions,
respectively, during movement of the walking beam in the clockwise
pivotal direction. A second or counterclockwise sequence of signals
may be produced for movement of the walking beam in the second
pivotal direction as the light emitter interrupts each of the
emitted light beams. The counterclockwise sequence of signals may
include third and fourth signals corresponding to when the walking
beam is at a third or fourth pivotal position during
counterclockwise walking beam movement. The third and fourth
signals may occur at substantially the same pivotal position as the
first and second signals. It will be understood by those skilled in
the art, however, that due to differences or variations in walking
beam velocity, acceleration and pumping unit structural geometry,
movement of the light interrupter may be different during the
clockwise pivotal movement of the walking beam than during the
counterclockwise walking beam movement, such that the third and
fourth signals may occur at pivotal positions different from the
first and second signals.
[0094] A load sensor may be secured to the walking beam or
otherwise on the pumping unit, such as near the polished rod 14, to
sense varying load forces during various walking beam pivotal
position points in the pumping cycle. The load sensor may produce
an electrical load signal representative of pumping forces, that
may be sampled during each pumping cycle as a function of walking
beam position and/or pumping cycle rate.
[0095] A computer/processor may be provided and connected, such as
electrically or optically, to each of the first and second light
detectors to receive and process the clockwise sequence of signals
and the counterclockwise sequence of signals from the detectors 172
and 174. The processor may analyze the clockwise sequence of
signals and the counterclockwise sequence of signals to detect or
determine a change in direction from the first pivotal direction of
the walking beam to the second pivotal direction. The processor 82
may use the determined change in direction to control initiation of
sampling of the electrical load signal, and the sampling rate.
[0096] As illustrated in FIG. 7, the light interrupter 260 may
include a bubble, such as a gas or liquid bubble, in a fluid filled
portion of the pivotal position sensor 163. The bubble 260 may act
to distort, refract or otherwise interfere with the light passing
between a light emitter and a light detector. A sequence of signals
representative of the position of the bubble 260 within the sensor
163 at various points in time may be generated by the light
detectors, facilitating determination by the processor of angular
position of the walking beam at each signal point. Thereby,
additional processing by the processor may be performed to provide
pump-off control of the pumping unit.
[0097] Other embodiments may include a plurality of emitters and
detectors. For example, third 169 and fourth 171 light emitters
with corresponding third 173 and fourth 175 light detectors
respectively aligned on opposing sides of the pivotal position
sensor 163, may be provided. The third 169 and fourth 171 light
emitters may be positioned between the first 168 and second 170
light emitters. The corresponding third 173 and fourth 175 light
detectors may be positioned between the first 172 and second 174
light detectors.
[0098] The light emitters 168, 169, 170, 171 and the light
detectors 172, 173, 174, 175, in conjunction with the light
interrupter, 160 or 260, may permit generation of a sequence of at
least four sets of signals for in each of the clockwise and the
counterclockwise pivotal directions. Two additional signals
corresponding to walking beam position may be generated during
clockwise walking beam movement, such as a fifth and sixth signals.
Two additional signals corresponding to walking beam position may
be generated during counterclockwise pivotal beam movement, such as
seventh and eighth signals. The signals may facilitate refined
sensing of pumping unit load conditions and determining changes in
walking beam velocity between successive pumping cycles,
particularly as pumping conditions change.
[0099] As discussed above in reference to quadrature spacings, it
may be understood that differential spacings could be used between
detectors and between emitters, in conjunction with specific sizes
of light interrupter bubbles 260 or solid objects 160, so as to
facilitate generation of at least two distinct out of phase signals
during each signal sequence. Thereby, the processor may determine a
pivotal direction of movement and may also sense rate or velocity
variations within each pumping cycle. It will also be understood by
those skilled in the relevant art that still other embodiments may
be provided with additional emitter/detector pairs to further
refine sensitivity.
[0100] A method of providing a pumpjack dynamometer readout may
include securing to the walking beam a pivotal position sensor 163
including a light interrupter 160 or 260 movably disposed within
the pivotal position sensor. A light may be directed from a
plurality of light emitters 168, 169, 170, 171 through an aperture
180 in the pivotal position sensor 163. The light from the
plurality of light emitters may be received through the aperture
180 by a respective, corresponding plurality of light detectors
172, 173, 174, 175 to thereby produce a sequence of signals. The
plurality of light emitters and the corresponding plurality of
light detectors may be mounted to the walking beam to be moveable
with the pivotal position sensor 163 as the walking beam moves in
each of the first and second pivotal directions.
[0101] The plurality of light emitters and the plurality of
corresponding light detectors may be positioned to provide at least
a first or clockwise sequence of electrical signals when the
walking beam moves in the first or clockwise pivotal direction, and
at least a second or counterclockwise sequence of electrical
signals when the walking beam moves in the second or
counterclockwise pivotal direction. A load cell or load transducer
may be included on the pumpjack to provide a variable electrical
load signal during the pumping cycle corresponding to the variable
load on the walking beam during the pumping cycle. The load signal
during at least one pumping cycle may be sampled by the processor.
Sample timing may be at least partially based on a determined or
measured pumping cycle rate or change from the clockwise sequence
of signals to the counterclockwise sequence of signals that occurs
during each pumping cycle when the walking beam changes from the
clockwise pivotal direction to the counterclockwise pivotal
direction.
[0102] Light received by a detector 172, 173, 174, 175 may be
interrupted, such as by refraction or blockage, with a light
interrupter movably disposed within the pivotal position sensor.
The interrupter 160 or 260 may move within the sensor 163 in
response to changing pivotal direction of the walking beam. Light
interrupter movement may be such as by rolling, sliding, gliding,
or as in the case of a bubble, by displacement.
[0103] The foregoing disclosure and description of the invention is
illustrative and explanatory thereof, and it will be appreciated by
those skilled in the art, that numerous changes, e.g., additional
photo detectors/emitters, only some of which have been mentioned
hereinabove, in the types, arrangement, order of operation as well
as in the various details of the illustrated construction or
combinations of features of the various dynamometer readout
elements may be made without departing from the spirit of the
invention.
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