U.S. patent application number 14/737124 was filed with the patent office on 2015-10-29 for wireless well fluid extraction monitoring system.
This patent application is currently assigned to James N. McCoy. The applicant listed for this patent is Dieter J. Becker, Darius K. Hathiram, James N. McCoy. Invention is credited to Dieter J. Becker, Darius K. Hathiram, James N. McCoy.
Application Number | 20150308257 14/737124 |
Document ID | / |
Family ID | 49289845 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150308257 |
Kind Code |
A1 |
McCoy; James N. ; et
al. |
October 29, 2015 |
Wireless Well Fluid Extraction Monitoring System
Abstract
A system for wirelessly monitoring a well fluid extraction
process, which operates in conjunction with a host computer. The
system includes a wireless base that has a base radio and a
communication port to interface with the host computer. The system
also has a first remote with a first remote radio that communicates
with the base radio using a radio protocol. The first remote also
has a first sensor interface that can receive a first sensor
signal. The first remote digitally samples the first sensor signal
at a predetermined sampling rate, and then communicates first
sampled data to the wireless base through the radio protocol. A
host software application, which executes on the host computer,
receives the first sampled data from the wireless base
communication port.
Inventors: |
McCoy; James N.; (Wichita
Falls, TX) ; Becker; Dieter J.; (Wichita Falls,
TX) ; Hathiram; Darius K.; (Austin, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
McCoy; James N.
Becker; Dieter J.
Hathiram; Darius K. |
Wichita Falls
Wichita Falls
Austin |
TX
TX
TX |
US
US
US |
|
|
Assignee: |
McCoy; James N.
Wichita Falls
TX
|
Family ID: |
49289845 |
Appl. No.: |
14/737124 |
Filed: |
June 11, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13437125 |
Apr 2, 2012 |
9080438 |
|
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14737124 |
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Current U.S.
Class: |
340/853.2 |
Current CPC
Class: |
E21B 47/13 20200501;
E21B 47/18 20130101; E21B 47/009 20200501; E21B 47/008
20200501 |
International
Class: |
E21B 47/00 20060101
E21B047/00; E21B 47/12 20060101 E21B047/12 |
Claims
1. A wireless dynamometer system, which operates in conjunction
with a computer to monitor performance of a sucker rod driven pump,
the system comprising: a host software application for execution on
the computer; a wireless base having a base radio transceiver
interfaced to the computer; a wireless remote having a sucker rod
clamp, and having a strain gauge fixed to said sucker rod clamp and
coupled to a first digital converter that samples, at a first
sampling rate, load signals indicative of instantaneous sucker rod
loads to generate a stream of load data; an accelerometer, fixed to
said wireless remote, and coupled to a second digital converter
that samples sucker rod instant rate of acceleration signals at a
second sampling rate to generate a stream of acceleration data; a
remote radio transceiver that transmits said stream of acceleration
data and said stream of load data to said host software application
through said base radio transceiver using a radio protocol, and
wherein said host software application receives and processes said
stream of acceleration data and said stream of load data to
generate and display, on the computer, a real time dynagraph
showing performance of the sucker rod driven pump, and wherein said
base radio transceiver and said remote radio transceiver utilize
said radio protocol to communicate host commands from said host
software application to said wireless remote, and to communicate
remote commands from said wireless remote to said host software
application, and wherein said host commands include a
synchronization signal sent to synchronize said first sampling rate
of said first digital converter and said second sampling rate of
said second digital converter.
2. The system of claim 1, and wherein: said sucker rod clamp
comprises a pretension adjustment means, and wherein said strain
gauge includes a pretension circuit that outputs a calibration
signal indicating said pretension adjustment means is within an
operating range.
3. The system of claim 2, and wherein: said wireless remote
includes an actuator coupled to said pretension circuit, wherein
actuation of said actuator couples said calibration signal to said
remote radio to transmit said calibration signal to said host
software application, for display on the computer, thereby enabling
visual confirmation of said strain gauge pretension.
4. The system of claim 1, and wherein: said host software
application displays a real time surface dynagraph, and calculates
and displays a real time down-hole pump dynagraph.
5. The system of claim 1, and wherein: said base radio transceiver
and said remote radio transceiver are frequency agile between a
configuration radio channel and data transfer radio channel, and
wherein said wireless remote operates on said configuration radio
channel by default and changes to said data transfer radio channel
upon receipt of a channel command from said host software
application.
6. The system of claim 1, and wherein: said remote wireless
transceiver periodically transmits an identity beacon that contains
a unique identification code for said wireless remote, and wherein
said base transceiver couples said unique identification code to
said host software application, thereby making said host software
application aware of the availability of said wireless remote, and
wherein said wireless remote is subsequently addressed according to
said unique identification code by said host software
application.
7. The system of claim 1, and wherein: said first sampling rate and
said second sampling rate are programmable by said host software
application, and wherein said host software application transmits a
sampling rate command to said wireless remote to programmably
control said first sampling rate and said second sampling rate.
8. The system of claim 1, and wherein: said host software
application analyzes said stream of acceleration data and said
stream of load data, and generates a graphical animation of a down
hole portion of the sucker rod driven pump.
9. The system of claim 1, and further comprising: a second wireless
remote having a second remote radio transceiver that communicates
with said base radio transceiver using said radio protocol, and
having a sensor interface to receive a stream of sensor signals,
and wherein said second wireless remote digitally samples said
stream of sensor signals and communicates second sampled data to
said host software application through said wireless base.
10. The system of claim 1, and wherein; said wireless remote
includes at least a first actuator coupled to said remote radio
transceiver, and wherein actuation of said actuator causes said
wireless remote to transmit an actuation command, as one of said
remotes commands, to said wireless base, and wherein said actuation
command is coupled from said wireless base to said host software
application and causes said host software application to send a
begin acquisition command, as one of said host commands, to said
wireless remote to begin acquisition and processing of said stream
of acceleration data and said stream of load data sensor data.
11. The system of claim 1, and wherein; said host commands include
an acquisition command for said wireless remote to begin, and a
cease acquisition command for said first remote to terminate, said
digital sampling and communication of said stream of acceleration
data and said stream of load data.
12. The system of claim 1, and wherein; said host commands include
a sampling rate command, which is sent to said wireless remote and
defines said first predetermined sampling rate and said second
predetermined sampling rate.
13. The system of claim 1, and wherein the wireless dynamometer
system is further adapted to take acoustic echo readings through a
well bore coupling in a well bore of a well fluid extraction
process, the system further comprising: an acoustic gun assembly
having a gas pressure reservoir gated with a solenoid valve to
selectively release a shock wave of gas pressure to the well bore
interface port; a solenoid drive circuit coupled to open said
solenoid valve in response to a fire command; a microphone
acoustically coupled to the well bore interface port to receive
echo signals resulting from said shock wave; a microphone convertor
coupled to output a digital microphone signal; a gun assembly radio
transceiver coupled to said microphone convertor and said solenoid
drive circuit, and adapted to communicate with said base radio
transceiver according to said radio protocol, and wherein said host
software application communicates said fire command, as one of said
host commands, to activate said solenoid valve to release said
shock wave, and wherein said gun assembly radio transceiver
communicates said digital microphone signal to said base radio
transceiver, thereby providing echo signals for analysis by said
host software application.
14. The system of claim 18, and wherein: said host software
application detects said shock wave of gas pressure within said
digital microphone signal to establish a reference time for
acoustic echo readings, also within said digital microphone
signal.
15. A method of wirelessly monitoring performance of a sucker rod
driven pump using a computer running a host software application,
which is interfaced with a wireless base having a base radio
transceiver that communicates using a radio protocol with a
wireless remote that includes a remote radio transceiver, wherein
the wireless remote includes a sucker rod clamp with a strain gauge
coupled to a first digital converter, and an accelerometer coupled
to a second digital converter, the method comprising the steps of:
generating a stream of load data using the first digital converter
by sampling strain gage signals at a first sampling rate, which are
indicative of instantaneous sucker rod loads; generating a stream
of acceleration data using the second digital converter by sampling
accelerometer signals at a second sampling rate, which are
indicative of sucker rod instant rate of acceleration; transmitting
the stream a load data and the stream of acceleration data to the
host software application using the radio protocol between the
remote radio transceiver and the base radio transceiver;
generating, and displaying on the computer, a real time dynagraph
by the host software application, by processing the steam of load
data and the stream of acceleration data, thereby showing
performance of the sucker rod driven pump; wirelessly communicating
host commands from the host software application to the wireless
remote, and communicating remote commands from the wireless remote
to the host software application, and synchronizing the first
sampling rate and the second sampling rate by wirelessly sending a
synchronization signal from the host software application to the
wireless remote.
16. The method of claim 15, and wherein the sucker rod clamp
includes a pretension adjustment, and the strain gauge includes a
pretension circuit that outputs a calibration signal, and further
comprising the step of: adjusting the pretension adjustment to
place the calibration signal within a predetermined operating
range.
17. The method of claim 16, and wherein the wireless remote
includes an actuator coupled to the pretension circuit, and further
comprising the steps of: wirelessly transmitting the calibration
signal to the host software application upon actuating the
actuator, and displaying calibration information on a display of
the computer, thereby enabling visual confirmation of the strain
gauge pretension.
18. The method of claim 15, further comprising the step of:
displaying, on the computer by the host software application, a
real time surface dynagraph, and calculating and displaying a real
time down-hole pump dynagraph by the host software application.
19. The method of claim 15, and wherein the base radio transceiver
and the remote radio transceiver are frequency agile between a
configuration radio channel and data transfer radio channel, and
further comprising the steps of: operating the wireless remote on
the configuration radio channel by default, and changing to the
data transfer radio channel upon receiving of a channel command
from the host software application.
20. The method of claim 15, and further comprising the steps of:
periodically transmitting an identity beacon, by the wireless
transceiver, that contains a unique identification code for the
wireless remote; coupling the unique identification code to the
host software application, thereby making the host software
application aware of the availability of the wireless remote, and
subsequently addressing the wireless remote according to the unique
identification code.
21. The method of claim 15, and wherein the first sampling rate and
the second sampling rate are programmable by the host software
application, and further comprising the steps of: transmitting,
from the host software application, a sampling rate command to the
wireless remote, thereby programming the first sampling rate and
the second sampling rate.
22. The method of claim 15, and further comprising the steps of:
analyzing the stream of acceleration data and said stream of load
data by the host software application, and generating a graphical
animation of a down hole portion of the sucker rod driven pump.
23. The method of claim 15, and wherein the wireless remote
includes an actuator coupled to the remote radio transceiver, and
further comprising the steps of: transmitting an actuation command
to the wireless base by the wireless remote upon actuating the
actuator, and coupling the actuation command to the host software
application, thereby causing the host software application to send
a begin acquisition command, as one of the host commands, to the
wireless remote to begin acquisition and processing of the stream
of acceleration data and the stream of load data sensor data.
25. The method of claim 15, and further comprising the steps of:
sending a sampling rate command, by the host software application,
to the wireless remote, thereby defining a first predetermined
sampling rate and a second predetermined sampling rate.
Description
RELATED APPLICATION
[0001] This is a Continuation application from U.S. patent
application Ser. No. 13/437,125 filed on Apr. 2, 2012.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to monitoring the operation
and performance of fluid extraction equipment and processes from a
subterranean well. More particularly, the present invention relates
to systems for wirelessly monitoring dynamic performance in a
sucker-rod pumped hydrocarbon well.
[0004] 2. Description of the Related
[0005] Some wells utilize a pumping system to extract oil, gas, and
water from subterranean well boreholes. Other wells rely on natural
reservoir pressure, including gas pressure to extract fluids. A
pumping system typically comprises a surface mounted reciprocating
drive unit coupled to a submerged pump by a long steel rod,
referred to as a Sucker-rod. The submerged pump consists of a
chamber, plunger, and a pair of check valves arranged to draw
fluids into the chamber and lift fluids to the surface on each
upstroke of the plunger. Wells that primarily produce gas can
employ a cyclical plunger in a plunger lift arrangement that
employs pressure differentials to purge liquids to the surface.
Since wells range in depths to many thousand feet, the forces and
pressures involved in the pumping operation are substantial. The
costs of drilling, assembling, and servicing such wells are also
substantial. Costs are only offset by efficient production of oil
and gas products from the well. Thus, the careful attention given
by operators to efficient and reliable operation of sucker-rod
pumped wells over many decades of experience can be readily
appreciated. Well operators can directly access and monitor surface
mounted well equipment performance by attaching certain sensors and
transducers and analyzing the data they produce. It is also
desirable for operators to monitor reservoir performance, however,
this information is not readily accessible from the surface
equipment, so specialized sensors and processing equipment are
required. Wells typically employ a wellhead assembly at the top of
the well borehole to seal the well fluids within a surface plumbing
system. A reciprocating sucker-rod enters the wellhead assembly
through a sliding seal, which requires that the rod be terminated
at the surface level by a polished portion, commonly referred to as
a polished rod. In a typical well, an electric motor drives the
polished rod up and down through a mechanical drive arrangement.
Thus, at the surface, the well equipment is accessible for
operators to monitor the movement and forces on the polished rod,
the power consumption characteristics of the electric drive unit,
and also the pressures and temperatures in surface plumbing and the
wellhead itself. In addition, the well casing and tubing string in
the well borehole are accessible at the surface level. The tubing
string is typically filled with well liquids and the annulus
between the tubing string and the well casing are typically filled
with gases down to a liquid level in the vicinity of the fluid
producing geological formation, which may be thousands of feet
below the surface. It is useful for operators to know the depth of
this liquid level as well as certain other fluid and mechanical
characteristics within the well bore. Liquid level measurements and
other subterranean casing data can be gathered from the surface
level using an acoustic pulse and echo sounding equipment.
[0006] Certain instruments for gathering well performance data are
known in the art. Among these are movement sensors and force
sensors that are connected to the reciprocating pump mechanism.
Others include electric current and voltage sensors connected to
the pump drive motor, tubing and casing pressure transducers,
temperature probes, as well as the aforementioned acoustic sounding
devices, sometimes referred to as an "echometer". In the prior art,
most of these sensors are utilized in a portable manner, being
carried from well to well by technicians as they conduct various
performance tests at various well sites. The prior art patents
cited below give the reader a substantial background on the types
of sensors and transducers used by operators and technicians. Note
that a common characteristic in these disclosures is the use of
wires and cables to interconnect between the sensors and a central
processing unit, such as a PC computer. While electrical cables are
a useful solution for interconnecting sensors and data processing
devices during well testing activities, they have certain issues.
First, since they must be built to rugged industrial standards,
they are expensive. Cables are prone to electric and stress
failures, particularly after frequent and repeated connection,
storage, and reconnection cycles. They also tend to collect dirt
and oil, which degrades their utility over time. It is also
relatively time consuming for technicians to deploy, connect, and
stow cables as they move from well to well. In addition, cables
assembles are both heavy and bulky.
[0007] Significant advancements in equipment and techniques for
gathering and processing surface data and generating down-hole data
have been contributed by McCoy et al., and are presented in a
series of patents, the teachings of which are hereby incorporated
by reference. The use of an accelerometer and strain gauge in a
polished rod transducer to implement a surface dynamometer have
been taught. The accelerometer advancements are presented in U.S.
Pat. No. 5,406,482 to McCoy et al., issued Apr. 11, 1995, for
METHOD AND APPARATUS FOR MEASURING PUMPING ROD POSITION AND OTHER
ASPECTS OF A PUMPING SYSTEM BY USE OF AN ACCELEROMETER, which
teaches that an accelerometer is mounted on the pumping system unit
to move in conjunction with the polished rod. An output signal from
the accelerometer is digitized and provided to a portable computer.
The computer processes the digitized accelerometer signal to
integrate it to first produce a velocity data set and second
produce a position data set. Operations are carried out to process
the signal and produce a position trace with stroke markers to
indicate positions of the rod during its cyclical operation.
[0008] The McCoy et al. advancements in the use of a strain gauge
in a surface dynamometer are presented in U.S. Pat. No. 5,464,058
to McCoy et al, issued Nov. 7, 1995, for METHOD OF USING A POLISHED
ROD TRANSDUCER, which teaches that a transducer is attached to the
polished rod to measure deformation, i.e., the change in diameter
or circumference of the rod to determine changes in rod loading.
The transducer includes strain gauges, which produce output signals
proportional to the change in the diameter or circumference of the
rod, which occurs due to changes in load on the rod. The transducer
may also include an accelerometer. The change in load on the
polished rod over a pump cycle is used in conjunction with data
produced by the accelerometer to calculate a down-hole pump card
according to the teachings of in the prior art cited herein. The
pump card showing changes in pump load is adjusted to reflect
absolute rod load by determining an appropriate offset. Various
ways to determine the offset are available. Since the pump plunger
load is zero on the down stroke when the upper check valve, called
the traveling valve, is open, the value necessary to correct the
calculated minimum pump value to a zero load condition may be used
as the offset. The offset can also be estimated by either a
calculation of the rod weight, a predetermined rod weight
measurement or an estimated load value by the operator. The
teachings of the '058 are hereby incorporated by reference.
[0009] A typical well is built by drilling a borehole and
installing a well casing. A tubing string is lowered into the well
casing. The well fluids are pumped to the surface by a pump at the
bottom, through the tubing string. Thus, there exists an annular
space between the casing and the tubing. The well fluids are
present in this space, and it is useful to know the liquid level of
the well fluids to better understand well operations and to improve
accuracy of certain measurements and calculations. In this regard,
McCoy et al. have also provided further advancements in the art of
measuring well casing and tubing liquid levels. These teachings are
presented in U.S. Pat. No. 5,117,399 to McCoy et al., issued May
26, 1992, for DATA PROCESSING AND DISPLAY FOR ECHO SOUNDING DATA,
which is directed to an echo sounding system with a acoustic gun
that is mounted to the wellhead of a borehole casing. The acoustic
gun produces an acoustic pulse that is transmitted down the casing
or tubing. The acoustic pulse produces reflections when it strikes
the tubing collars and the surface of the well fluid. A microphone
detects the reflections to produce a return signal. This signal is
digitized and stored. The teachings of the '399 patent are hereby
incorporated by reference.
[0010] A further advancement in the use of echo sounding equipment,
referred to as an "echometer", is taught by McCoy et al, in U.S.
Pat. No. 6,634,426, issued Oct. 21, 2003, for DETERMINATION OF
PLUNGER LOCATION AND WELL PERFORMANCE PARAMETERS IN A BOREHOLE
PLUNGER LIFT SYSTEM. The teachings of this patent are hereby
incorporated by reference. This patent provides a method for
measuring well performance in the case of a gas producing well that
employs a pressure operated plunger lift apparatus to clear fluids
out of the well, and the use of an echometer to evaluate plunger
and well performance. In another patent by McCoy, and automatic
echometer is taught, and this is U.S. Pat. No. 4,934,186, issued
Jun. 19, 1990, for AUTOMATIC ECHO METER. This patent teaches an
apparatus that enables continuous calculations of the depth of the
fluid level within a well bore during a test interval. A sonic
event is generated in the well bore, and the reflected sonic
signals from down hole tubing collars and the fluid surface are
sensed and recorded. By knowing the depth of the tubing collars,
the fluid depth and speed of sound in the overlying gas can be
computed. Subsequently, the apparatus generates sonic events and
records the travel time for the sound to reflect off the fluid
surface and return. Measurements of the actual fluid depth and
sonic velocity are made at regular intervals, and interpolated
between actual measurements to allow the variation in fluid level
to be calculated from the measurements of travel time. The
teachings of the '186 patent are hereby incorporated by
reference.
[0011] Thus, is can be appreciated that there is a need in the art
for a system and method for use in plunger lift and sucker-rod
pumped oil and gas well industry that further assists operators and
technicians in more efficiently performing on-site well performance
testing and analysis.
SUMMARY OF THE INVENTION
[0012] The need in the art is addressed by the systems and methods
of the present invention. The present disclosure teaches a system
for wirelessly monitoring a well fluid extraction process, which
operates in conjunction with a host computer. The system includes a
wireless base that has a base radio and a communication port to
interface with the host computer. The system also has a first
remote with a first remote radio that communicates with the base
radio using a radio protocol. The first remote also has a first
sensor interface that can receive a first sensor signal, which
corresponds to performance metrics of the well fluid extraction
process. The first remote digitally samples the first sensor signal
at a predetermined sampling rate, and then communicates first
sampled data to the wireless base through the radio protocol. A
host software application, which executes on the host computer,
receives the first sampled data from the wireless base
communication port, and processes the performance metrics to output
well fluid extraction performance data.
[0013] In a specific embodiment of the foregoing system, the first
remote further includes a second sensor interface that receives a
second sensor signal. The first remote digitally samples the second
sensor signal at a second predetermined sampling rate, and then
communicates second sampled data to the wireless base through the
radio protocol. The host software application also receives the
second sampled data from the wireless base communication port. In a
refinement to this embodiment, the predetermined sampling rate and
the second predetermined sampling rate are periodically
synchronized, including the time at which sampling is initiated. In
another refinement to this embodiment, where the system is
monitoring the performance of a sucker rod pump in the well fluid
extraction process, the system further includes an accelerometer
coupled to the first sensor interface, which outputs the first
sensor signals representative of the instant acceleration of the
sucker rod. It also includes a strain gauge coupled to the second
sensor interface, which outputs the second sensor signals
indicative of the instant load of the sucker rod, and then the host
software application utilizes the first sampled data and the second
sampled sate to generate a dynamometer dynagraph.
[0014] In a specific embodiment, where the foregoing system is for
use with a well fluid extraction process that employs plunger lift
liquid removal that operates with respect to casing annulus
pressure, tubing pressure, and liquid level, the system further
includes a third sensor interface that receives a third sensor
signal, which is digitally sampled to wirelessly communicate third
sampled data to the wireless base. The host software application
then receives the third sampled data from the wireless base
communication port and uses it to analyze plunger lift performance
of the well fluid extraction process. In a further refinement, the
system includes a first sensor couple to acoustically detect the
liquid level in the well fluid extraction process and output the
first sensor signal, and a second sensor coupled to detect the
casing annulus pressure in the well fluid extraction process and
output the second sensor signal, and also a third sensor coupled to
detect the tubing pressure in the well fluid extraction process and
output the third sensor signal. In another refinement, the first
sampled data, the second sampled data, and the third sampled data
are processed by the host software application to determine plunger
location in the well fluid extraction process, the plunger lift
well performance, or the plunger cycle times.
[0015] In a specific embodiment of the foregoing system, the first
remote further includes a first sensor for gathering first
performance information for the well fluid extraction process,
which is coupled to provide the first sensor signal to the first
sensor interface. In a refinement to this embodiment, the first
sensor is selected from amongst a pressure transducer, a
temperature transducer, an accelerometer, a strain gauge, a voltage
transducer, an electric current transducer, a position transducer,
and a microphone. In another refinement, the first sensor is
calibrated according to a first calibration coefficient stored in
the first remote, and the first wireless remote transfers the first
calibration coefficient to the wireless base through the radio
protocol in response to a command. The command may be generated by
the host software application and communicated to the first remote
through the radio protocol. In another embodiment, the well fluid
performance data is selected from a surface dynagraph, a down-hole
pump dynagraph, a pump animation, a drive torque analysis, a
mechanical loading analysis, and structure dynamics analysis.
[0016] In a specific embodiment of the foregoing system, the
predetermined sampling rate is programmable by the host software
application, and is communicated to the first remote through the
wireless base using the radio protocol. In another specific
embodiment, the system further includes a unique identification
code stored in the first remote, and, the unique identification
code is transferred to the wireless base through the radio
protocol, and then, the first remote is subsequently addressed
according to the unique identification code by the wireless base
and the host software application.
[0017] In a specific embodiment of the foregoing system, the base
radio and the first remote radio are frequency agile between a
configuration radio channel and data transfer radio channel. The
first remote operates on the configuration radio channel by default
and then changes to the data transfer radio channel upon receipt of
a channel command from the wireless base, and the host software
application may initiate the channel command in the wireless base.
In a refinement to this embodiment, the first remote periodically
transmits an identity beacon that contains a unique identification
code for the first remote, and, the wireless base adds the unique
identification code to a list of remote unique identification
codes, and then transfers the list of remote unique identification
codes to the host software application, making the host software
application aware of the first remote, as well as any other
remotes.
[0018] In a specific embodiment of the foregoing system, the
wireless base transmits a synchronization signal at predetermined
intervals, and the first remote employs the synchronization signal
as a timing reference to the predetermined sampling rate. In a
refinement to this embodiment, the synchronization signal is
referenced to a hardware timing circuit in the wireless base, which
eliminates timing jitter and timing drift in the clock, which may
be caused by software latency or clock instability. In another
refinement to this embodiment, the predetermined intervals are
programmable by the host software application.
[0019] In another refinement to the prior embodiment, the
synchronization signals establish timing frames for transmission of
the first sampled data from the first remote to the wireless base.
This is further refined where the first sampled data is transmitted
in a data slot within the timing frames this is defined by an
offset time from the synchronization signal and a duration time.
Further, the timing frames may include a portion for the
communication of base commands from the wireless base to the first
wireless remote, and a portion for the communication of remote
commands from the first remote to the wireless base.
[0020] In a specific embodiment of the foregoing system, the radio
protocol establishes timing frames having a data portion for the
transmission of the first sampled data, and a base portion for the
transmission of base commands from the wireless base to the first
wireless remote, and a remote portion for the communication of
remote commands from the first remote to the wireless base. The
base commands and remote commands can be used to implement
additional embodiments.
[0021] In a specific embodiment of the foregoing system the system
can take acoustic echo readings through a well bore coupling in a
well bore of the well fluid extraction process. This embodiment
further includes an acoustic gun assembly with a gas pressure
reservoir that is to selectively release a shock wave of gas
pressure to a well bore interface port. It also has a microphone
acoustically coupled to the well bore interface port. The
microphone is coupled to the first sensor interface to provide the
first sensor signal. The first remote further includes a solenoid
drive interface coupled to the solenoid. The first remote, in
relation to a release of a shock wave of gas pressure, communicates
the first sensor signal representative of acoustic reflections
within the well bore, which are digitally sampled according to the
predetermined sampling rate and communicated to the wireless base
in the data portion of the timing frames, and the host software
application detects the shock wave of gas pressure to establish a
reference time for the acoustic echo readings. In a refinement to
the previous embodiment, the acoustic gun further includes a
solenoid valve coupled to selectively release the shock wave of gas
pressure in response to a fire command from the host software
application.
[0022] In a refinement to the previous embodiment, the host
software application allocates a first fraction of time from the
data portion of the timing frames for the transmission of the first
sampled data according to a total number of remotes, including the
first remote, and also according to the predetermined sampling
rate, and then the first remote transmits the first sampled data
within the first fraction of time. In a refinement to this
embodiment, the radio protocol further includes an error detection
protocol, and the wireless base requests retransmission of the
first sampled data when an error is detected, and then the first
remote retransmits the first sampled data within that first
fraction of time. In yet another refinement, the host software
application divides the data portion of the timing frames into
plural remote data slots, and assigns a first remote data slot to
the first remote for the transmission of the first sampled
data.
[0023] In another refinement to the previous embodiment, the first
remote includes a first actuator coupled to the first remote radio,
and then, actuation of the actuator causes the remote radio to
transmit an actuation command to the wireless base within the
remote portion of the timing frames. In an improvement to this
embodiment, the actuation command is coupled from the wireless base
to the host software application and causes the host software
application to initiate a sequence of actions to begin acquisition
and processing of sensor data from the well fluid extraction
process.
[0024] In a specific embodiment of the foregoing system, the first
remote includes a visual indicator coupled to the first remote
radio. The first remote is responsive to receipt of a base command
received in the base portion of the timing frames to activate the
visual indicator, and also the base command may originate in the
host software application.
[0025] In a specific embodiment of the foregoing system, the host
software application generates host commands that are coupled by
the communication port to the wireless base, and, a portion of the
host commands are translated to base commands from subsequent
transmission to the first remote. In a refinement to this
embodiment, the wireless base is responsive to a host command to
configure the wireless base to accumulate the first sampled data
for a period of time after the communication port is disconnected
from the host computer. In another refinement, the host commands
include a command for the first remote to begin, and a command for
the first remote to terminate, the digital sampling and
communication of the first sampled data. In another refinement, the
host commands include a command to define the timing and duration
of the data portion, the base portion, and the remote portion of
the timing frames. And, in yet another refinement, the host
commands include a command to define the predetermined sampling
rate.
[0026] In a specific embodiment of the foregoing system, where the
wireless base further includes a GPS receiver, the wireless base
returns a present set of GPS coordinates to the host software
application upon command. In another specific embodiment, the radio
protocol employs the IEEE 802.15.4 physical layer
specification.
[0027] In a specific embodiment, the system further includes a
second remote with a second remote radio that communicates with the
base radio using the radio protocol, and that has a second sensor
interface to receive a second sensor signal. The second remote
digitally samples the second sensor signal at a second
predetermined sampling rate to communicate second sampled data to
the wireless base through the radio protocol. In a refinement to
this embodiment, the wireless base transmits a synchronization
signal at predetermined intervals, and the first remote employs the
synchronization signal as a timing reference to the predetermined
sampling rate, and the second remote employs the synchronization
signal as a timing reference to the second predetermined sampling
rate.
[0028] In another refinement to the previous embodiment, the
predetermined sampling rate and the second predetermined sampling
rate are periodically synchronized with the synchronization signal,
including the time at which sampling is initiated. In another
refinement, the synchronization signals establish timing frames,
which includes a data portion for transmission of the first sampled
data and the second sampled data to the wireless base, and also,
the timing frames include a base portion for the communication of
base commands from the wireless base to the first wireless remote
and the second wireless remote. In a further refinement, the host
software application divides the data portion of the timing frames
into plural remote data slots, and assigns a first remote data slot
to the first remote for the transmission of the first sampled data,
and a second remote data slot to the second remote for the
transmission of the second sampled data.
[0029] In a further refinement to the previous embodiment, the
first data slot within the timing frames is defined by a first
offset time from the synchronization signal and a first duration
time, and the second data slot within the timing frames defined by
a second offset time from the synchronization signal and a second
duration time. In yet another refinement, the first predetermined
sampling rate and the second predetermined sampling rate are
independently programmable by the host software application, and
are communicated to the first remote and the second remote through
the wireless base using the base portion of the timing frames.
[0030] The present disclosure also teaches a wireless dynamometer
for measuring performance of a sucker rod driven pump in a well
fluid extraction process, which is used with a wireless enabled
host computer running a host software application that generates
dynamometer dynagraphs from sucker rod acceleration and load data.
The wireless dynamometer includes a housing with a clamp arm for
clamping onto a polished rod portion of the sucker rod so that they
move together. The housing contains an accelerometer that outputs
acceleration signals representative of the instant acceleration of
the sucker rod, which is then coupled to a first converter that
digitally samples the acceleration signals at a predetermined
sampling rate to generate sampled acceleration data. A strain gauge
is disposed on the clamp arm, which outputs load signals indicative
of the instant load of the sucker rod, and that is coupled to a
second converter that digitally samples the load signals in
synchronous with the predetermined sampling rate to produce sampled
load data. There is a radio that communicates with the host
computer in accordance with a radio protocol, and the radio
receives, and transfer to the host computer, the sampled
acceleration data and the sampled load data.
[0031] In a specific embodiment of the foregoing dynamometer, the
host software application conducts further analysis of the sampled
acceleration data and the sampled load data to generate a graphical
animation of a down hole portion of the sucker rod driven pump. In
another specific embodiment, the host software application
processes the sampled acceleration data and the sampled load data
to calculate both a surface dynagraph and a downhole dynagraph.
[0032] The present disclosure also teaches a wireless acoustic
sounding apparatus for generating an acoustic pulse and gathering
return echo signals in a well bore in a well fluid extraction
process, and also for use with a wireless enabled host computer.
The wireless acoustic sounding apparatus includes an acoustic gun
assembly that has a gas pressure reservoir gated with a solenoid
valve to selectively release a pulse of gas pressure to a well bore
interface port, and a solenoid drive circuit coupled to activate
the solenoid valve in response to a fire command. A microphone is
acoustically coupled to the well bore interface port that outputs
echo signals representative of an initial acoustic pulse and
subsequent acoustic reflections from the well bore, and further
coupled to a converter that digitally samples the echo signals at a
predetermined sampling rate to generate sampled echo data. A radio
communicates with the host computer in accordance with a radio
protocol that establishes timing frames having both a data portion
for the transmission of the sampled echo data to the host computer,
and a base portion for the receipt of commands from the host
computer. The radio is coupled to the solenoid drive circuit to
activate the solenoid valve upon receipt of the fire command from
the host computer, thereby generating an acoustic pulse, which
results in the return echo, which causes the microphone to output
the echo signals. The sampled echo data is then coupled to the
radio and transmitted in the data portion of the radio protocol,
which thereby enables wireless reception by the host computer. In a
refinement to this embodiment, the host software application
utilizes the sampled echo data to calculate a pressure gradient of
a gas column and a liquid column in the well bore.
[0033] In a specific embodiment of the forgoing system, the host
software application utilizes the sampled echo data and the well
pressure data to calculate a series of downhole pressures at a
predetermined depth for a pressure transient test to analyze well
performance.
[0034] The present invention also teaches a wireless dynamometer
for measuring performance of a sucker rod driven pump in a well
fluid extraction process, for use with a wireless enabled host
computer running a host software application that generates
dynamometer analysis from sucker rod acceleration and load data.
The wireless dynamometer includes a housing that is connected to
the sucker rod to move together therewith. An accelerometer is
fixed to the housing, which outputs acceleration signals
representative of the instant acceleration of the sucker rod, that
are coupled to a first converter to digitally samples the
acceleration signals at a predetermined sampling rate to generate
sampled acceleration data. Also, a strain gauge is disposed in the
housing and outputs load signals indicative of the instant load on
the sucker rod, which are coupled to a second converter that
digitally samples the load signals in synchronous with the
predetermined sampling rate to produce sampled load data. A radio
communicates with the host computer in accordance with a radio
protocol, and the radio is coupled to receive, and transfer to the
host computer, the sampled acceleration data and the sampled load
data.
[0035] In a specific embodiment to the foregoing dynamometer, the
host software application conducts analysis and processing of the
sampled acceleration data and the sampled load data to generate a
graphical animation of a downhole portion of the sucker rod driven
pump. In another embodiment, the host software application
processes the sampled acceleration data and the sampled load data
to calculate a dynagraph from a selected location along the sucker
rod, selected from a surface position and a downhole position.
[0036] The present invention also teaches a wireless acoustic
sounding apparatus for generating an acoustic pulse and gathering
return echo signals in a well bore in a well fluid extraction
process, and for use with a wireless enabled host computer. The
apparatus includes an acoustic gun assembly with a gas pressure
reservoir that is gated with a manually operated valve to
selectively release a pulse of gas pressure to a well bore
interface port. A microphone is acoustically coupled to the well
bore interface port and outputs echo signals representative of an
initial acoustic pulse and subsequent acoustic reflections from the
well bore. The microphone is also coupled to a converter that
digitally samples the echo signals at a predetermined sampling rate
to generate sampled echo data. A radio communicates with the
wireless enabled host computer in accordance with a radio protocol
for the transmission of the sampled echo data to the wireless
enabled host computer. Then, the sampled echo data can be coupled
to the radio and transmitted, thereby enabling wireless reception
by the wireless enabled host computer.
[0037] In a specific embodiment of the foregoing acoustic sounding
apparatus, the sampled data is processed by a host software
application to determine a liquid level depth.
[0038] The present invention also teaches a wireless acoustic
sounding apparatus for generating an acoustic pulse and gathering
return echo signals in a well, which also employs a pressure
transducer for gathering well pressure data in a well fluid
extraction process. This apparatus includes an acoustic gun
assembly with a gas pressure reservoir gated with a manual valve to
selectively release a pulse of gas pressure to a well bore
interface port. A microphone is acoustically coupled to the well
bore interface port that outputs echo signals representative of an
initial acoustic pulse and subsequent acoustic reflections from the
well bore. The microphone is also coupled to a converter that
digitally samples the echo signals at a predetermined sampling rate
to generate sampled echo data. A pressure transducer is positioned
to sense the well pressure and is coupled to a converter that
digitally samples the pressure signal at a predetermined sampling
rate to generate sampled pressure data. A radio communicates with
the wireless enabled host computer in accordance with a radio
protocol for the transmission of the sampled echo and pressure
data. The, the sampled echo and pressure data are coupled to the
radio and transmitted, thereby enabling wireless reception by the
wireless enabled host computer. A host software application
processes the sampled echo data and the sampled pressure data to
obtain a casing annulus gas flow rate. In addition, the host
software application may process the sampled echo data and the
sampled pressure data to determine downhole pressures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a system diagram of two oil well pumps under test
using a wireless well monitoring system according to an
illustrative embodiment of the present invention.
[0040] FIG. 2 is a drawing of an oil well reciprocating drive unit
employing a wireless well monitoring system according to an
illustrative embodiment of the present invention.
[0041] FIG. 3 is a side view drawing of a wireless polished rod
transducer according to an illustrative embodiment of the present
invention.
[0042] FIG. 4 is a top view drawing of a wireless polished rod
transducer according to an illustrative embodiment of the present
invention.
[0043] FIG. 5 is a functional block diagram of a wireless polished
rod transducer according to an illustrative embodiment of the
present invention.
[0044] FIG. 6 is a functional block diagram of acoustic liquid
level meter according to an illustrative embodiment of the present
invention.
[0045] FIG. 7 is a drawing of a remote wireless sensor interface
for an acoustic liquid level meter according to an illustrative
embodiment of the present invention.
[0046] FIG. 8 is a diagram of an acoustic liquid level meter with
wireless remote interfaced to a wellhead casing according to an
illustrative embodiment of the present invention.
[0047] FIG. 9 is a functional block diagram of a horseshoe type
strain gauge wireless remote according to an illustrative
embodiment of the present invention.
[0048] FIG. 10 is a drawing of the wireless remote for a horseshoe
style strain gauge according to an illustrative embodiment of the
present invention.
[0049] FIG. 11 is a drawing functional block diagram of a pressure
transducer wireless remote according to an illustrative embodiment
of the present invention.
[0050] FIG. 12 is a drawing of a wireless remote for a pressure
transducer according to an illustrative embodiment of the present
invention.
[0051] FIG. 13 is a functional block diagram of a wireless base
computer interface according to an illustrative embodiment of the
present invention.
[0052] FIG. 14 is a front view drawing of a wireless base computer
interface according to an illustrative embodiment of the present
invention.
[0053] FIG. 15 is a back view drawing of a wireless base computer
interface according to an illustrative embodiment of the present
invention.
[0054] FIGS. 16A, 16B, and 16C are system level functional block
diagrams of a wireless well performance monitoring system according
to an illustrative embodiment of the present invention.
[0055] FIG. 17 is an information flow diagram for a wireless well
performance monitoring system according to an illustrative
embodiment of the present invention.
[0056] FIG. 18 is an information processing diagram for a wireless
well performance monitoring system according to an illustrative
embodiment of the present invention.
[0057] FIG. 19 is a software architecture diagram for a wireless
well performance monitoring system according to an illustrative
embodiment of the present invention.
[0058] FIG. 20 is a system diagram for a wireless well performance
monitoring system according to an illustrative embodiment of the
present invention.
[0059] FIG. 21 is a wireless remote state transition diagram for a
wireless well performance monitoring system according to an
illustrative embodiment of the present invention.
[0060] FIG. 22 is a wireless remote state transition diagram for a
wireless well performance monitoring system according to an
illustrative embodiment of the present invention.
[0061] FIG. 23 is a wireless remote state transition diagram for a
wireless well performance monitoring system according to an
illustrative embodiment of the present invention.
[0062] FIG. 24 is a data frame timing diagram for a wireless well
performance monitoring system according to an illustrative
embodiment of the present invention.
DESCRIPTION OF THE INVENTION
[0063] Illustrative embodiments and exemplary applications will now
be described with reference to the accompanying drawings to
disclose the advantageous teachings of the present invention.
[0064] While the present invention is described herein with
reference to illustrative embodiments for particular applications,
it should be understood that the invention is not limited thereto.
Those having ordinary skill in the art and access to the teachings
provided herein will recognize additional modifications,
applications, and embodiments within the scope hereof and
additional fields in which the present invention would be of
significant utility.
[0065] In considering the detailed embodiments of the present
invention, it will be observed that the present invention resides
primarily in combinations of steps to accomplish various methods or
components to form various apparatus and systems. Accordingly, the
apparatus and system components and method steps have been
represented where appropriate by conventional symbols in the
drawings, showing only those specific details that are pertinent to
understanding the present invention so as not to obscure the
disclosure with details that will be readily apparent to those of
ordinary skill in the art having the benefit of the disclosures
contained herein.
[0066] In this disclosure, relational terms such as first and
second, top and bottom, upper and lower, and the like may be used
solely to distinguish one entity or action from another entity or
action without necessarily requiring or implying any actual such
relationship or order between such entities or actions. The terms
"comprises," "comprising," or any other variation thereof, are
intended to cover a non-exclusive inclusion, such that a process,
method, article, or apparatus that comprises a list of elements
does not include only those elements but may include other elements
not expressly listed or inherent to such process, method, article,
or apparatus. An element proceeded by "comprises a" does not,
without more constraints, preclude the existence of additional
identical elements in the process, method, article, or apparatus
that comprises the element.
[0067] The present invention advances the art by providing a system
for measuring and testing equipment and processes that operate in a
well fluid extraction process using a diverse range of sensors and
control functions that operate wirelessly and that address critical
real-time timing and synchronization issues so as to enable
accurate and reliable information processing. The system interfaces
wireless remote units connected to sensors and transducers with a
host software application running on a host computer, which both
gathers and processes the test information, but also manages user
interface, data presentation, system control and timing features of
the system. The system contemplates multiple types of sensors,
multiple simultaneously operating sensors, and closely related
information sources, and a range of convenience feature for user
interface, data management, and operation of the system. FIG. 1
presents an exemplary field environment for operation of an
illustrative embodiment of the present invention.
[0068] Reference is directed to FIG. 1, which is a system diagram
of two oil well pump jacks that are located in a single oil field,
and which are connected to an illustrative embodiment system for
conducting real-time performance tests using wireless interfaces
for the test instrumentation. A first pump jack 8 and a second pump
jack 10 are coupled to lift well fluids out of a first well head
casing 12 and a second well head casing 22, respectively. "Pump
jack" is a customary term used to describe a walking-beam type
cyclical reciprocating drive for sucker-rod driven down-hole pumps.
Pump jack 8 is illustrated at the top of its stroke where the
polished rod 14 is drawn upward and fully extended out of the
wellhead casing 12. A wireless polished rod transducer ("WPRT") 16
is temporarily clamped to the polished rod 14 and travels up and
down with the rod's stroke. A radio transceiver in WPRT 16
communicates within a wireless network 2 that generally operates in
compliance with the physical layer specification of I.E.E.E.
protocol standard 802.15.4, although it will be appreciated that
other radio protocols could be employed. In the illustrative
embodiment, the wireless network operates in the 2.4 GHz band,
although other radio frequency bands could also be employed. A
wireless acoustic liquid level meter and pressure transducer
interface 18, which is generally referred to as a wireless remote
fire gun ("WRFG") because the acoustic liquid level test is
initiated with a burst of gas pressure released in gun-like
fashion, is pneumatically coupled to the wellhead casing 12 through
a valve gated plumbing fitting. The WRFG 18 operates to initiate an
acoustic echo test into the well casing and then detecting the
return echo signal for further analysis. The WRFG 18 also comprises
pressure transducers that sense well casing pressure. All of these
signals are coupled to wireless transceiver 20, which also
communicates with wireless network 2. A separate wireless pressure
transducer 21 is coupled to the well tubing string to sense the
tubing pressure and communicate pressure reading data into the
network 2. Similarly, pump jack 10 is illustrated at the lowest
position in its stroke, where the polished rod 24 is fully lowered
into the well casing 22. Polished rod 24 also has a WPRT 26
temporarily attached thereto, which communicates with the wireless
network 2. A second WRFG 28 with wireless transceiver 30 is
attached to well head casing 22 and wirelessly communicates within
the wireless network 2. In the illustrative embodiments, the
protocol defines up to sixty-four data channels when operating at
data sample rates of 30 HZ per channel. Higher data rates are
supported, with corresponding reduction in the number of
simultaneous data channels. For example, data rates as high a 4 kHz
may be employed to provide high resolution of system performance
where needed.
[0069] FIG. 1 illustrates a test set-up for a well site having two
pumping oil wells. Such tests are run occasionally, so it is
preferable for the WPRT's 16 and 26 and the WRFG's 18 and 28 to be
attached to the wells on the day of the test, then removed at the
end of the test, to be taken to the next well site for subsequent
testing elsewhere. The data gathered during the test is coupled to
a processor 4, which is typically a laptop type personal computer.
The interface to the processor 4 is via a wireless base unit 6
connected to the processor through a serial port and wirelessly
communicating within the wireless network 2 using the
aforementioned radio protocol standard. Of course, other wireless
systems and protocols could be employed with the teachings of the
present invention, as will be appreciated by those skilled in the
art. The wireless features of this system design are beneficial in
that they eliminates the need for interconnecting cables between
the host computer and the polished rod transducers and the remote
fire gun. Such cables are heavy, cumbersome, subject to failure,
and generally require greater effort to utilize. However, it is to
be understood that the real-time measuring, processing, testing and
display features of the present invention could be implemented with
a system employing a mixture of wireless interfaces or wired
interfaces if so desired. For example, this would be beneficial if
an operator chose to gradually transition from a wired to a
wireless testing system. The processor 4 functions as a host
computer for the wireless system, and executes host software
application programs and algorithms that enable a wide range of
functions of the present invention, including gathering test
measurements, transmitting and receiving control signals, managing
user interface, maintaining reference database information,
processing data to provide real-time results, generating graphical
and alpha-numeric output data, and driving hardware devices
including a display and serial port, as well as other features of
the present invention discussed more thoroughly hereinafter. One
aspect of the illustrative embodiment system is to select one or
more wireless remotes that are within RF range of a wireless base,
thereby forming a group, configure the group to select which radio
and data channels to use and at what sample rates, and perform a
data acquisition operation that provides a live real-time data
stream accessible from the wireless base and the host computer,
which can be viewed in real time or stored for later analysis. The
systems also contemplates independent group formation and
operation. It provides the ability to select wireless remotes and
corresponding sensors and assign them to one of more groups, for
example, a group for each of the wells 8, 10 in FIG. 1. Each group
can be configured and instructed to perform acquisitions
independent of the other group. A new group can in fact be formed
while another group is already acquiring data. This is one of the
reasons there are dual radios on the wireless base unit. This
concept can be extended to have additional groups with additional
radios on the base.
[0070] In the case of a single wireless base operating with a
single group of wireless remotes, an illustrative embodiment is
arranged as follows. The wireless remotes have three operating
states; standby (transmitting a slow beacon), awake (transmitting a
fast beacon), and acquire. Wireless remotes power up into the
standby state. In this state they operate on an assigned
configuration radio channel and transmit a short beacon at periodic
intervals programmable in the range from 2 to 30 seconds. Between
beacons the wireless remotes remains in a very low power state to
conserve batteries. A beacon communicates the wireless remote
identification and state (identification, model number, battery
state, and etc. Each wireless remote transitions to the awake state
if it receives a suitable response from a wireless base indicating
that the base intends to utilize it. During the awake state, the
wireless remote transmits its beacons more frequently (0.1 to 1
sec). Operation remains on the configuration radio channel. During
this state the base can configure the wireless remote. This
includes setting which channels will be used for an acquisition, at
what sample rate, gain, and data format. The wireless remote is
also assigned a group number, which defines the data radio channel,
and a timeslot during which it must transmit its data during
acquisition. During this time the base must always await a beacon
to initiate a communication with the wireless remote. Each wireless
remote transitions to the Acquire state in a two-step sequence. It
must receive an acquire command from the base. It must acknowledge
this command and then switch to the data radio channel in receive
mode. If a StartSync command is received, this triggers the start
of data acquisition. The wireless powers up and begins to listen
for wireless remote beacons on the configuration radio channel. A
host software application, running on the host computer attached to
the base, retrieves and maintains a list of audible wireless
remotes. The host can then instruct the base to configure a subset
of wireless remotes. The host provides all of the configuration
information, however, the configuration information can be stored
in the base and utilized during a stand-alone mode of operation. A
start command from the host, or the base, sets off the sequence
that transitions the selected wireless remotes to data acquisition
mode. In the illustrative embodiment, the wireless remote states
transition backwards into standby either based on timeouts or when
instructed by the base.
[0071] Reference is directed to FIG. 2, which is a drawing of a
surface mounted reciprocating pump drive 83 coupled to a wellhead
casing 61 under test according to an illustrative embodiment of the
present invention. The top of well is terminated by a well head
assembly 61 consisting of a casing head and pumping tee, which
couples to the top of the well casing 34 and the top of the tubing
string 56. The sucker rod 54 passes through the well head casing
61, and a gland seal 62 is used to seal gases and liquids from the
ambient environment. The top portion of the sucker rod 54 is
polished to maintain a tight seal, and is thusly referred to as the
polished rod. The liquids and gases produced by the well 32 are
routed to processing and storage equipment (not shown) by a
plumbing system 64. An acoustic echometer 66 is pneumatically
coupled to the annulus between the interior of the casing 34 and
the exterior of the tubing string 56. An acoustic shock wave is
released into the annulus, and the resulting echo is detected by
the acoustic liquid level meter 66, which is used to measure the
actual liquid level down hole and other useful data. A wireless
remote transceiver 70 is used to communicate with the echometer 66.
The echometer 66 also includes a pressure sensor that detects the
casing pressure at the surface level. In addition a tubing string
pressure sensor 68 is coupled to the interior cavity of the tubing
string 56 to detect the pressure therein, and also wirelessly
communicates within the aforementioned wireless network. The well
itself is built by drilling a borehole down from a surface level to
a geological formation that contains the desired well fluids, and
in the illustrative embodiment those are crude oil and natural gas.
As the well is drilled, a well casing 34 is placed into the
borehole to maintain its integrity over time. After the well casing
34 is built, a tubing string 56 is lowered into the well casing 34.
The tubing string 56 is generally comprised of plural tubing
sections that are interconnected with plural couplings 58, although
continuous tubing strings are known in the art. A pump assembly
(not shown) is attached to the bottom of tubing string 56. The
down-hole pump is driven by a sucker-rod 54 that is located within
the tubing string 56. The sucker-rod extends up to the surface
level, and is terminated with the polished rod portion 54 to
sealably engage the gland seal 62.
[0072] FIG. 2 also illustrates a conventional reciprocating drive
unit 83, also referred to as a pump jack, which cycles the polished
rod 54 up and down to drive the subterranean well pump (not shown).
The drive unit 83 consists of a reduction drive with Pitman arm 82
coupled to a walking beam 80, which is supported on a Sampson post
84. A horse head 78 on the walking beam 80 supports a cable bridle
76 which is connected to the polished rod 54 by a carrier bar 74.
These are well known terms of art. A wireless polished rod
transducer ("WPRT") 72 of the present invention is temporarily
clamped to the polished 54, and cycles up and down with the
polished rod 54 during the test procedure. Alternatively, a
horseshoe style strain gauge may be disposed about the polished rod
at the carrier bar to sense changing compressive forces between the
two.
[0073] A plunger lift well, discussed at length in the McCoy et al.
patent number 6,634,426 employs a plunger, or piston, within the
well tubing sting. Since the well typically expels gas under
formation pressure, a reciprocating pump is not employed. However,
water and other liquids can accumulte in the well bore, and it is
necessary to expel them. The plunger is utilized, driven by
differential pressures in the casing and tubing string, to push
liquid in the tubing string to the surface. After the liquid is
cleared, the plunger falls back down the tubing string. An
important test for determining the condition of a producing oil
well is a bottom hole pressure build up test. The results of this
test indicate the need for well stimulation, work over, or
recompletion, as well as permit the determination of formation
characteristics. Occasionally, pressure sensors can be placed
directly at the formation level within the borehole for direct
measurement of pressure. However, more frequently, the presence of
pumping rods in the tubing prevents such direct measurement. In
those situations, it is common to use acoustic techniques to
determine the level of the fluid within the borehole, and calculate
the bottom hole pressure estimating the density and depth of the
fluid column and overlying gas. The systems and methods of the
present invention are useful for gathering and processing such
data.
[0074] Reference is directed to FIG. 3, which is a functional block
diagram of a wireless polished rod transducer ("WPRT") 200
according to an illustrative embodiment of the present invention.
The wireless polished rod transducer is one type of wireless remote
available to operators under the illustrative embodiments of the
present invention. Attention is again directed to the McCoy et al.
U.S. Pat. No. 5,406,482 and U.S. Pat. No. 5,464,058 U.S. patents
discussed in the Background of the Invention section. The
illustrative embodiment of FIG. 3 advances the art with the use of
a wireless transceiver 204 and certain advanced processing
techniques and features to enhance and simplify well testing
procedures, in particular, the gathering of dynamometer data in
real time. The physical sensors of the WPRT 200 are an
accelerometer 226 and a group of strain gauges wired in a
Wheatstone bridge circuit 228 (collectively "strain gauge"). The
accelerometer 226 detects acceleration in the up and down movement
of the polished rod. The raw signal is amplified by amplifier 222
and filtered by anti-aliasing filter 218 prior to being digitally
samples at a selectable predetermined rate, which may be 30 Hz, by
analog to digital converter 214. The sampled acceleration signal is
then coupled to processor 210. The strain gauge 228 is clamped to
the polished rod by C-shaped clamp arm structure 230 and setscrew
232. The setscrew 232 is tightened to preload the bridge circuit
228 into an acceptable operating range of the strain gauge 228. As
the polished rod cycles up and down, the tensile load changes and
the strain gauge 228 detects minute changes in the rod diameter.
This data is processed to determine the magnitude of the tensile
load on the polished rod. The differential voltages across nodes
the Wheatstone bridge 228 are amplified by differential amplifier
224 and are then filtered by anti-aliasing filter 220 before being
sampled at a selectable predetermined rate, which may be 30, Hz by
analog to digital converter 216. The sampled strain data is then
coupled to a processor 210 in the WPRT circuit 200. It is
preferable that the sampling rate of the accelerometer 226 and
strain gauge 228 are the same, and that they are precisely
synchronized so as to provide the most accurate sampled data for
subsequent analysis, processing, and graphical presentation.
Therefore, the ADC 214 and ADC 216 clocks may be synchronized so
that the data sample sets precisely coincide in time.
[0075] The processor 210 in the WPRT 200 of FIG. 3 has access to
memory 212 for temporary storage of sampled data, variables,
reference values, unit identity, and program object code. An
I.E.E.E. 802.15.4 compliant transceiver 204 is used as the physical
layer communications link into a local wireless network for which
the wireless base (discussed hereinafter) serves as network host
controller. The processor 210 implements the higher communications
protocol layers for packet assembly, addressing, and control
functions, which will be more fully discussed hereinafter. The
transceiver 204 interfaces to the radio network using an antenna
202. A rechargeable battery and power circuit 206 in the WPRT 200
provides power to the circuits discussed above. The illustrative
embodiment WPRT 200 employs a function specific user interface that
enable the user to enter commands via three key actuators 207, 209,
211 coupled to the processor 210 through an interface circuit 215.
The user interface also includes three visual indicators 201, 203,
205, which are LED's in the illustrative embodiment, also coupled
to the processor 210 though an interface circuit 213. In the
illustrative embodiment, the actuators and indicators include an
ON/OFF 201, 207; INSTALL pretension 203, 209, and ACQUIRE data 205,
211, which will be more fully discussed hereinafter. Other
embodiments can incorporate other user interface functions,
including higher resolution visual displays, matrix keyboards and
so forth.
[0076] Reference is directed to FIG. 4 and FIG. 5, which are top
view and side view drawings, respectively, of a wireless polished
rod transducer ("WPRT") 200 according to an illustrative embodiment
of the present invention. The structure of FIG. 4 and FIG. 6
correspond, in part, to the functions of FIG. 3. The WPRT 200 is
fabricated as a single structural housing 236, machined from a
suitable material such as stainless steel, to provide a rugged and
unified device. One end of the device is formed in the
aforementioned clamp arm 230 configuration, with a setscrew 232
provided to clamp the unit onto a polished rod 234 at the time a
test is conducted. The strain gauge sensors 228 are locate along
the clamp arm 230 to detect the strain forces applied to the
polished rod 234, which change along with minute changes in the rod
234 diameter. The accelerometer 226 is fixed within the housing 226
of the WPRT 200 as well. The other end of the WPRT 200 frame
comprises a cavity 240 for housing the aforementioned circuitry. A
printed circuit board 242 and circuit components are located
therein. The storage battery 244 is also locating in the cavity
240. The antenna 202 for the transceiver 204 extends out from the
cavity 240. The ON/OFF 201, 207; INSTALL pretension 203, 209, and
ACQUIRE data 205, 211 actuators and indicators appear on the
exterior of the WPRT 200. The indicators 201, 203, and 205 are
multi-color LEDs in the illustrative embodiment, and function as
follows. The ON/OFF LED 201 is off when the power is off, and
displays a slow green flash rate when on and ready. At power up,
the battery status is indicated with a series of quick flashes, up
to ten total, which correspond to the battery state. If an error
condition occurs during use, the indicator 201 provides three quick
red flashes. The INSTALL LED 203 is off when the unit is not being
installed. When the INSTALL actuator 209 is pressed, the LED 203
provides three quick green flashes. As the set screw 232 is
tightened, the LED 203 gives quick green flash when the pretension
is too loose, quick red flash when the tension is too tight, and
stead green when the tension is in the acceptable range. The
ACQUIRE LED 205 is off when the unit is not acquiring test data.
When the ACQUIRE actuator 211 is pressed, the LED 205 gives three
quick green flashes. As the unit starts acquisition, the LED 205
gives a slow flash, then goes to a fast green flash during
acquisition. If there is an error condition, the LED 205 gives
three red flashes. Thus it can be appreciated that the WPRT is a
single, compact, fully integrated remote unit for the illustrative
embodiment system that does not require any cable interfaces, and
that can readily be clamped onto a polished rod and travel together
therewith. The only occasional connection that needs to me made is
to recharge the battery 244, through a battery connector (not
shown).
[0077] Reference is directed to FIG. 6, which is a functional block
diagram of an integrated acoustic liquid level meter and wireless
network remotes unit 100 according to an illustrative embodiment of
the present invention. Since the acoustic liquid level meter
wireless remote 100 releases a strong acoustic pulse to initiate a
measurement, it is referred to as a "gun", and since it can be
remotely activated, it is referred to as a remote fire gun. In the
case of the wireless embodiment, it is referred to as a wireless
remote fire gun, or "WRFG". Although, some embodiments can be
manually fired by a technician. Since the WRFG 100 is coupled to
the well casing annulus, it is also used as a host interface for a
casing pressure sensor 114. The acoustic echometer 100 includes a
solenoid valve 104 to release a pulse of precharged gas from a
pressure canister 105 on demand. A piezoelectric microphone 108 us
acoustically coupled to the casing interface to `listen` to the
initial pulse of gas and the return echo signals, and the
microphone 108 produces an analog electrical signal proportional to
the acoustic echo signal. The solenoid valve 104 is switch by a
power drive circuit 106, which is coupled to a small signal
interface 107 from a processor 126. The microphone 108 is coupled
to an amplifier 110, which is coupled to an anti-aliasing filter
112, before being sampled by an analog to digital converter 122. In
the illustrative embodiment, the microphone is sampled at 1 kHz to
yield a finer resolution that most of the other sensor, which are
typically sampled at 30 Hz. The casing pressure sensor 114 is
coupled to anti-aliasing filter 116 before being sampled at 30 Hz
by analog to digital converter 123. The sampled signals are then
coupled to processor 126. The processor 126 has access to memory
128 for temporary storage of sampled data, variables, reference
values, unit identity, and program object code. The processor also
maintains a circular buffer of sampled microphone signals. The
purpose of this is to process that data to detect the initial pulse
of the compressed gas, so as to establish a timing reference for
the subsequent echo signals. This is particularly useful in the
case of a manual fired gun, where the software has no other
information to determine when an echo test is being initiated. In
this case, the detection of a gas pulse alters the buffer from a
circular format to a data output format of collecting the desired
data. An I.E.E.E. 802.15.4 compliant transceiver 130 and antenna
134 are used as a radio communications link into a local wireless
network. A rechargeable battery and power circuit 132 in the WRFG
100 provides power to the circuits discussed above. The
illustrative embodiment WRFG 100 employs a function specific user
interface that enable the user to enter commands via three key
actuators 111, 113, 115 coupled to the processor 126 through an
interface circuit 119. The user interface also includes three
visual indicators 105, 107, 109, which are LED's in the
illustrative embodiment, also coupled to the processor 126 though
an interface circuit 117. In the illustrative embodiment, the
actuators and indicators include an ON/OFF 105, 111; ZERO 107, 113,
and FIRE pulse 109, 115, which will be more fully discussed
hereinafter. Other embodiments can incorporate other user interface
functions, including higher resolution visual displays, matrix
keyboards and so forth.
[0078] Reference is directed to FIG. 7, which is a drawing of a
remote wireless sensor interface 102 portion for the wireless
remote acoustic liquid level meter 100 according to an illustrative
embodiment of the present invention. The interface includes the
actuators and indicators including the ON/OFF 105, 111; ACQUIRE
107, 113, and FIRE pulse 109, 115, described about. The
transceiver, processor, interface circuits, and battery circuits
are also disposed within the interface, with the antenna 134
disposed on the exterior. The interface 102 is attached to the WRFG
housing 100.
[0079] Reference is directed to FIG. 8, which is a drawing of the
acoustic liquid level meter with wireless remote, WRFG, 100
interface with a wellhead casing 101 according to an illustrative
embodiment of the present invention. FIG. 8 generally corresponds
to the functions of FIG. 6. In FIG. 8, the WRFG 100 is acoustically
coupled to the well casing 101 so as to conduct acoustic pulse and
echo sounding measurements down into the well casing 101. The WRFG
100 includes the solenoid valve 104 and the piezoelectric
microphone 108 (internal to the WRFG). A compressed gas reservoir
105 with a pressure gauge 107 extend from the WRFG 100. There is
also a casing pressure senor 114 (also internal to the WRFG 100)
pneumatically coupled to the casing through the WRFG 100. All of
the components are interface to the control circuit 102, which
includes the interfaces, processor and wireless transceiver.
Antenna 134 communicates within the aforementioned wireless
network. All of these instruments are temporarily interface to the
wellhead by plumbing connection at the time of testing.
Additionally, FIG. 8 illustrates a tubing string 103 wireless
remote pressure sensor 350 with antenna 367 that is pneumatically
coupled to measure the tubing 103 pressure level. The separate
wireless remote pressure sensor 350 will be more fully described
hereinafter.
[0080] FIG. 9 is a drawing functional block diagram of a wireless
remote unit utilizing a horseshoe style strain gauge according to
an illustrative embodiment of the present invention. The horseshoe
stain gauge 304 is configured to insert between a rod and carrier
on the mechanical drive unit of a sucker rod driven well pump. The
horseshoe is thus compressed to varying degrees as the load on the
rod cycles through each stroke of the pump. A strain gauge 302 is
disposed in the horseshoe 304 so as to produce a corresponding
stain signal, which is proportional to the force. The differential
signal output from the bridge 302 is amplified by differential
amplifier 306, and then filtered by anti-aliasing filter 308 before
being digitally sampled by analog to digital converter 310. The
sampling occurs at 30 Hz in the illustrative embodiment, however,
this value is programmable up to 4 kHz. The sampled data is coupled
to a processor 312, which executes a program to packetize the data,
store the data in memory 314, and also couple packets to
transceiver 318 for transmission into the wireless network. The
memory 314 also stores other variables, program code, and so forth
as needed. A rechargeable battery and power circuit 316 is also
provided. The wireless remote 300 also employs a function specific
user interface that enable the user to enter commands via two key
actuators 328, 330 coupled to the processor 312 through an
interface circuit 322. The user interface also includes two visual
indicators 324, 326, which are LED's in the illustrative
embodiment, also coupled to the processor 312 though an interface
circuit 320. In the illustrative embodiment, the actuators and
indicators include an ON/OFF 324, 328 and ZERO 326, 330. The ZERO
function sets a bias offset with the pump is stationary, so that
subsequent force data can be referenced to that value.
[0081] Reference is directed to FIG. 10, which is a drawing of the
horseshoe style strain gauge wireless remote electronics module 300
according to an illustrative embodiment of the present invention.
The module 300 presents the antenna 319 and the user interface,
consisting of the ON/OFF 324, 328 and ZERO 326, 330 actuators and
indicators. The electronics module can be integrated with the
horseshoe sensor 304.
[0082] Reference is directed to FIG. 11, which is a drawing
functional block diagram of a pressure transducer wireless remote
350 according to an illustrative embodiment of the present
invention. This remote 350 is also shown interfaced to the tubing
string in the well in FIG. 8. In FIG. 11, the pressure transducer
352 is of conventional design, outputting a signal proportional to
the input pressure to the device. The signal output from the
pressure transducer 352 is filtered by anti-aliasing filter 354
before being digitally sampled by analog to digital converter 356.
The sampling occurs at 30 Hz in the illustrative embodiment. The
sampled data is coupled to a processor 358, which executes a
program to packetize the data, store the data in memory 360, and
also couple packets to transceiver 366 for transmission into the
wireless network. The memory 360 also stores other variables,
program code, and so forth as needed. A rechargeable battery and
power circuit 362 are also provided. The wireless remote 350 also
employs a function specific user interface that enables the user to
enter commands via two key actuators 372, 274 coupled to the
processor 358 through an interface circuit 378. The user interface
also includes two visual indicators 368, 370, which are LED's in
the illustrative embodiment, also coupled to the processor 358
though an interface circuit 376 In the illustrative embodiment, the
actuators and indicators include an ON/OFF 368, 372 and ZERO 370,
374. The ZERO function sets a bias offset so that subsequent
pressure data can be referenced to that value. The output interface
320 can also include other output functions. For example, a dry
contact closure output, driven by a command received from the
wireless base or the host software application, can be provided to
drive auxiliary device, such as motors, lights, alarms, relays,
solenoids, controlled devices and so forth. Similarly, the system
design, radio protocol, and host software application can
accommodate custom input device through the input interface 322.
This is possible with all of the wireless remotes in the
illustrative embodiments.
[0083] Reference is directed to FIG. 12, which is a drawing of the
wireless remote electronics module 350 for a pressure transducer
wireless remote according to an illustrative embodiment of the
present invention. The module 350 presents the antenna 367 and the
user interface, consisting of the ON/OFF 368, 372 and ZERO 370, 374
actuators and indicators. The electronics module can be integrated
with the pressure transducer 352 if desired.
[0084] Reference is directed to FIG. 13, which is a functional
block diagram of a wireless base 400 computer interface according
to an illustrative embodiment of the present invention. The
wireless base 400 hosts the radio network under the IEEE 802.15.4
physical layer. The wireless base communicates with all the
wireless remotes using the radio protocol and data protocols of the
illustrative embodiment. The wireless base 400 also communicates
with the host computer through a USB serial interface. Other
computer and radio protocols, including proprietary protocols could
also be employed. For example, the interface to the computer could
be a parallel interface, Bluetooth, or WiFi, for example.
Similarly, the radio network with the wireless remotes could be
WiFi, WiMax, Bluetooth, other promulgated standard or a proprietary
design as well. It is noteworthy that one aspect of the
illustrative embodiment that is addressed with care is power
conservation and battery life. The remotes are designed to operate
for extended periods of time on a single battery charge. This issue
is addressed in several ways. However, one fundamental decision is
that of selecting a radio environment that is power efficient and
has the requisite data bandwidth and reasonable component costs.
Given the sampling rate range of up to 4 kHz and the typical number
of sensors that might be needed at a well site, perhaps a dozen,
the IEEE 802.15.4 specification was selected. This is the IEEE
protocol standard employed in the ZigBee standard. While the
illustrative embodiment system does not operate in compliance with
the entire ZigBee standard, which defines several layers of a
network communication protocol stack and certain system features,
the illustrative embodiment does operate in compliance with the
physical layer of the ZigBee protocol stack. This is significant in
that the radio hardware components for ZigBee have been developed
and are available off-the-self from several ZigBee system suppliers
at competitive prices.
[0085] The IEEE 802.15.4 protocol is a specification for a suite of
high level communication protocols using small, low-power digital
radios based on an IEEE 802 family of standards for personal area
networks. These are suitable for industrial equipment that requires
short-range wireless transfer of data at relatively low rates, as
compared to broadband telecommunication systems. The 802.15.4
defined data rate is 250 kbps, and is well suited for periodic or
intermittent data or a single signal transmission from a sensor or
input device. IEEE 802.15.4 chip vendors typically provide
integrated radios and microcontrollers with between 60 KB and 256
KB flash memory at competitive costs. IEEE 802.15.4 operates
unlicensed in the industrial, scientific and medical (ISM) radio
bands of 2.4 GHz. The IEEE 802.15.4 network layer natively supports
both star and tree type networks, and generic mesh networks. In the
illustrative embodiments of the present invention, a star network
topology is employed, which is implemented in a proprietary fashion
using unique device identifiers, MAC addressing, as well as error
detection and correction by requested retransmission. Every
802.15.4 network must have one coordinator device, tasked with its
creation, the control of its parameters and basic maintenance.
Within star networks, the coordinator must be the central node, and
in the illustrative embodiments, this is the wireless base
controller 400.
[0086] IEEE 802.15.4 builds upon the physical layer and media
access control defined in IEEE standard 802.15.4 for low-rate
WPANs. Because IEEE 802.15.4 nodes can go from sleep to active mode
in 30 ms or less, the latency can be low and devices can be
responsive. Because IEEE 802.15.4 nodes can sleep most of the time,
average power consumption can be low, resulting in long battery
life. The illustrative embodiments of the present invention takes
advantage of this structure, employing a very low power sleep modes
with infrequent beacons to the wireless base, and also a fast
beacon mode that is still relatively power efficient. It is only
during actual data acquisition mode that the wireless remotes
consume significant amounts of battery power. In the 2.4 GHz band
there are 16 IEEE 802.15.4 channels, with each channel requiring 5
MHz of bandwidth. The illustrative embodiment employs at least two
of these radio channels. A first channel as a default configuration
channel, and then a second channel is allocated for data
acquisition. In the event the system detects poor radio performance
based on transmission errors or signal to noise performance,
alternate radio channels can be specified, selected, or
automatically selected to improve radio link performance. Two
separate transceivers are provided in the wireless base 400 so that
both signaling function can occur simultaneously. In the 2.4 GHz
band, 802.15.4 provides up to 250 Kbit/s data rates. The 802.15.4
radios use direct-sequence spread spectrum coding, which is managed
by the digital stream into the modulator. Offset quadrature
phase-shift keying (OQPSK) that transmits two bits per symbol is
used in the 2.4 GHz band. Again, the raw, over-the-air data rate is
250 Kbit/s per channel in the 2.4 GHz band. Transmission range is
between 10 and 75 meters (33 and 246 feet) and up to 1500 meters
for IEEE 802.15.4 pro are possible, although it is heavily
dependent on the particular environment. The output power of the
radios is typically 0 dBm.
[0087] Thus, the functional block diagram in FIG. 13 illustrates
two 802.15.4 transceivers 402, 404, with their respective antennas
403, 405. Both are interfaced to a central processor 410, which may
be the native ZigBee processor. Power is supplied from a
rechargeable battery and power circuit 406. A memory 154 is
provided for executable code, data storage, variables, and other
memory requirements. A USB communication port 412 is provided for
interface to a host computer 414, as are known in the art. A host
software application of the illustrative embodiment executes on the
host computer 412, which functions will be more fully discussed
hereinafter. The power circuit may drawn power from the host
computer through the USB interface 412. Note that a GPS receiver
416 may be included in the wireless base, which is coupled to the
processor 410. This enables the processor to obtain instant
geographic coordinates for communications to the host computer.
This is useful in correlating geographically oriented database
records with the physical location of the base 400, such as
locating well information for a present well analysis test. The
host computer 414 provides a substantial control point and user
interface for the wireless base 400 as well as the several wireless
remotes. However, the wireless base 400 still comprises a limited
user interface, include a reset button 422 and two indicators for
On/Off 420 and Status 424, which are coupled to the processor
through an interface circuit 418. In another aspect of the
illustrative embodiment, the wireless base can operate in a
stand-alone mode, separated from the host computer and host
software application. This is referred to as a data-logger, and
runs with the wireless remotes to gather and store test data. This
is accomplished by transferring operating software, data, and
variables from the host into the memory 154, then disconnecting the
host allowing the wireless base 400 to run for memory. An external
battery can be connected to power supply 406 to enhance running
duration. The host computer and software application are used to
set-up and start test, and later to download the collected data,
but are disconnected during test. Power and heat are issues that
are overcome vis-a-vis leaving a PC at the well site. Liquid level
testing, repetitive, watching fluid level, during pumping, during
static. Shut pump off, watch fluid levels refill, etc.
[0088] Reference is directed to FIG. 14 and FIG. 15, which is a
front view drawing and a rear view drawing, respectively, of a
wireless base 400 computer interface according to an illustrative
embodiment of the present invention. The two antennas 403, 405 are
illustrated, as well as the previously mentioned On/Off 420 and
Status 424 indicators. The Reset actuator 422 enables the operator
to conduct a hardware reset of the wireless base 400 if needed. In
addition, a USB port physical connector 413 is provided for cable
interface to the host computer (not shown). A DC power connector
407 is provided to the connection of an external power supply to
facilitate rapid battery charging.
[0089] Reference is directed to FIGS. 16A, 16B, and 16C, which are
system level functional block diagrams of a wireless well
performance monitoring system according to an illustrative
embodiment of the present invention. FIG. 16A illustrates the
overall hardware and FIGS. 16B and 16C add the software structure
integration of the illustrative embodiment. A portable computer
448, such as an IBM compatible personal computer running the
Windows operating system, serves as the host computer for the
system, running a software application 450 called the TAM
Application, which is an acronym coined by the Echometer Company,
Wichita Falls, Tex., for Total Asset Management. The wireless base
440 of the illustrative embodiment it interfaced to the host
computer 448 through a USB interface 446. Within the host software
application 450, a USB driver 454, manages the physical serial
interface. The communications between the host software application
and the wireless base are all data packet communications, so a Data
Acquisition ("DAQ") Service 452 is provided in the host software
450 to manage the data packet assembly, routing, and addressing
functions between the host application 450 and the wireless base
440.
[0090] As noted earlier, the wireless base in FIG. 16A includes two
separate radio transceivers that enable it to simultaneously
communicate on two separate channels through two antenna 441, 443.
This capability can be used to maintain a configuration radio
channel while simultaneously acquiring sensor data on another radio
channel, or two data gathering channels can be operated
simultaneously, thereby doubling the data bandwidth of the system.
In FIG. 16, the first radio 441 sets up a first wireless network
438 transferring data from two wireless remotes, Remote Unit A 432
and Remote Unit B 436. Remote Unit A 432 is coupled to transducer
430 to sample data therefrom, and Remote Unit B is coupled to
transducer 434 to sample data therefrom. Note that two separate
wireless remotes 432, 436 operate simultaneously on a single radio
channel. This is possible because the data channel is time division
multiplexed into time slots that the system assigns to individual
remotes. Synchronization is accomplished using a sync pulse
transmitted from the wireless base 440. Wireless Remote Unit C 444
with its transducer 442 communicates with the other transceiver
antenna 439 in the wireless base on the configuration channel,
where status, configuration, and command functions are managed.
Remote Unit C 444 could also be assigned to a second data channel
through the second antenna 443, and begin data acquisition and
transfer to the wireless base 440.
[0091] The TAM host software application 450 is further subdivided
into plural functional elements in FIG. 16C. FIG. 16C is a diagram
illustrates a broad view of what is inside the host software
application 450. The USB Driver 454 and DAQ Service 452 were
discussed above. It should be noted that the host application 450
can either process data from a live real-time test and acquisition
process, or it can process stored data from earlier collected data.
The processing in either case is essentially the same. If the test
is a "live" test, the data stream and results are being acquired
from the hardware through the DAQ Service 452. If the test is a
"recalled" test, the data stream is recalled by the Data Manager
466 from previously stored data. Each test data set contains an
Acquisition data set that is, or was, fed by the DAQ Service 452.
The analysis contains several components that divide up the work of
locating, processing and totaling pump strokes. The User Interface
456 has components that know how to display the results to the user
and allow the user to interact with the analysis. The user can
change settings in the analysis that will cause the results to be
recalculated and redisplayed. A Recall Test component is
responsible for loading historical tests from the Data Manager 452.
The Acquire Test component is also responsible for setting up data
acquisition with the DAQ Service 452 and creating a "live" test to
fill with data from the hardware.
[0092] The DAQ Service 452 in FIG. 16B and FIG. 16C provides access
to the hardware and supplies data streams from the hardware. The
DAQ Service 452 runs primarily in the background, except for an
Acquisition ("AQC") Manager portion that runs in the foreground for
user access to the DAQ functions. As the name suggestion, the DAQ
Service 452 provides data acquisition services. On one end it
communicates with the wireless base unit 448 using the USB driver
454. On the other end is the interface to the host software
application 450 through the ACQ Manager portion. The DAQ Service
452 provides a complement of data acquisition functionality to the
host application 450, and provides a level of abstraction that
hides the complexity needed to communicate and control the data
acquisition devices.
[0093] The Real-time Dynamometer Module 458 in FIG. 16C is a
processing function that takes data streams and presents the
calculated results to the user through the User Interface 456. In
the case of dynamometer testing, the input data to the Real-time
Dynamometer Module 458 takes in load and acceleration data from the
sensors and then outputs dynamometer plots and other useful
results. There is a lot of processing and auto-processing that
occurs, much of it subject to the McCoy et al. patents recited in
the Background of the Invention section of this disclosure.
[0094] The Data Manager 466 in FIG. 16C is responsible for
serializing data sets from and to disk storage. The Data Manager
466 is a central location to store. The Data Manager 466 has a
structure that represents the data that will be persistent between
application runs. Depending on the type of test that is being
acquired, the Data Manager 466 maybe responsible for managing very
large data sets where part of the data resides in memory and part
of the data resides on disk. The Data Manager 466 is responsible
for handling these processes in a seamless fashion so that the
Real-Time Dynamometer Module 458 can seamlessly process any data
set.
[0095] The Hardware Manager 464 in FIG. 16C functions to keep the
User Interface 456 in sync with the current state of the system
hardware, which can change from time to time. The Hardware Manager
464 maintains a cached list of the sensors, remembers the last
sensors used at the well and knows which sensors the computer has
used before. The Hardware Manager 464 is responsible for
maintaining a list of sensor coefficients that go with each sensor.
The user enters them once, and then the hardware manager saves them
to disk for future sessions. The Hardware Manager 464 is also a
central location that all User Interface 456 components can go to
for a list of sensors or to configure the hardware.
[0096] The Event Dispatcher 462 in FIG. 16C is a generic tool for
the various components in this system to notify each other about
events. It is a communication mechanism for module A to tell module
B that it needs to do some work. The Event Dispatcher 462 is used
throughout the application to communicate between components. The
Event Dispatcher 462 is used to be a gateway between background and
foreground communication. This allows the DAQ Service 452 to notify
the foreground that something in the background has happened and
needs attention. The Event Dispatcher 462 is also used in the
foreground to allow components to communicate with each other in a
generic way.
[0097] The Session Manager 468 in FIG. 16C is responsible for
coordinating the utility functions of the Data Manager 466, well
data, Real-Time Dynamometer Module 458 and Hardware Manager 464.
The Session Manager 468 is, in a sense, a manager of managers. The
Session Manager 468 handles application events across different
managers. The Session Manager 468 is also responsible for tracking
the current "session" that contains the user's data. There is the
concept of the "current session" or "current dataset" that the user
is working in. All tests that are acquired go in this current
session.
[0098] Reference is directed to FIG. 17, which is an information
flow diagram for the Real Time Dynamometer Module 472 in the host
application software according to an illustrative embodiment of the
present invention. The DAQ Service provides real-time load and
acceleration data 470 streamed from the wireless dynamometer sensor
(not shown) and feeds it the Real Time Dynamometer Module 472 in
the TAM Host Software Application. The data is processed to
calculate and produce output 474 in various forms, including a
real-time surface dynamometer dynagraph, a real-time down-hole pump
dynagraph, and various tabulated data that relies upon the data
stream. FIG. 18 presents an even more detailed view of a data
processing schemes in the host software application.
[0099] Reference is directed to FIG. 18, which is an information
processing diagram for a wireless well performance monitoring
system 475 according to an illustrative embodiment of the present
invention. FIG. 18 shows a broad view of what is happening inside
and outside the real-time dynamometer module 484. The process
includes a current test data set 482 component, an analysis process
464 component, a user interface 496 component to display the
results, a recall test 482 component, and an acquire test 478
component. The test is a "live" test if the results are being
acquired from the hardware in real-time through the DAQ Service
476. Otherwise the test has been "recalled" 482 by the data manager
from a disk 480 or other storage media, and is historical. The
current test 482 contains a streaming data set that is fed by the
DAQ service 476. The analysis component 484 contains several
internal components that divide up the work of locating, processing
and totaling pump strokes. The User Interface 496 has components
that arrange a convenient display of the results to the user and
allow the user to interact with the analysis process. The user can
change settings in the user interface 496 that will cause the
results to be recalculated and redisplayed. The Recall Test 482
component is responsible for loading historical tests from the data
manager. The Acquire Test 478 component is responsible for setting
up data acquisition with the DAQ Service 476 and creating a "live"
test to fill with data from the hardware.
[0100] With respect to FIG. 18, as well as other illustrative
embodiments, the live acquire mode and historical recall mode are
comparable yet different. The host software application has two
distinct modes that it operates in, live acquire mode and recall
mode. It is important to understand the difference that "acquire"
mode refers to a real-time test that is presently using the
hardware to supply data for calculations and "recall" mode, which
operates on historical data that has been saved to disk and is
being recalled from disk to be presently calculated and displayed.
The same module and analysis routine can be used for both modes,
but the source of the data is different. For acquire mode, the data
is streamed from the hardware into a temporary test that the user
can save or discard once the data has been acquired. The analysis
routines look at this temporary test to calculate results. For
recall mode, the data has already been collected and the analysis
routine looks at the test that is loaded from disk and calculates
results from this recalled test.
[0101] The data flow for recall mode in FIG. 18 is very similar to
the acquire mode. The main difference is where the test comes from.
In acquire mode the test is created by the Acquire Test component
478. In recall mode, the test is loaded from the data manager
through the Recall Test component 482. The Recall Test component
482 then notifies the analysis to run and use the loaded test as
the source. The data is already contained in the test and the
analysis routine 484 uses the data to calculate results to be shown
on the user interface 496. The user interface 496 reflects that the
test shown on the screen is a "recalled" test and not a "live"
test.
[0102] The analysis component 484 in FIG. 18 is the primary
calculation and data processor of the dynamometer module 475. It
processes real-time data 482 to determine strokes and calculates
results for each stroke. There are five sub-components inside the
analysis component 484 that have different responsibilities. Data
moves through the analysis module 484 from right to left in FIG.
18, beginning with the stroke pre-processor 486.
[0103] The stroke pre-processor 486 in FIG. 18 is designed to take
a stream of raw acceleration data and isolate whole pump stroke
cycles ("strokes"). This process employs complex algorithms and
filters accomplish this. The output of the stroke pre-processor 486
is a beginning and end index of each stroke, which is passed to the
stroke management component 488 to be inserted in the list of
strokes. The stroke pre-processing 486 keeps track of where it is
in the raw data and just needs to be told when new data is
available to be processed.
[0104] The stroke management component 488 in FIG. 18 is
responsible for managing the list of strokes that have been
identified by the stroke pre-processor 486. It is also responsible
for computing the down-hole dynagraph plots for each stroke. This
involves using the wave equations discussed in the McCoy et al.
patents identified hereinbefore, to compute the down-hole dynagraph
plot points from the surface dynagraph data. Once the surface and
down-hole dynagraphs for each stroke are computed, other results
are then calculated on a per-stoke basis or over a selected
interval of strokes. The surface and down-hole dynagraph 482
calculation is a convenient way to get an at-a-glance view for each
current stroke. The user might want to always see the most current
stroke. In that situation, this computation simply notifies the
foreground when the next stroke is computed and available. The user
also might want to browse through some older strokes and get
information like pump fillage from the stroke. This component
calculates details about a stroke for the user. The data component
492 calculates averages and totals, and tracks things like the peak
polished rod loading, which is a running peak. These calculations
are composites of information from all of the strokes. This module
492 is responsible for doing the calculations when new stroke data
is available from stoke management 488. The user might want to
specify a certain range for the averages and totals, or they might
look at everything. This is done at this level. The overlay module
494 generates a surface card overlay by gathering the required data
needed to show a range of cards drawn overlaid on top of each
other. The user might specify a certain range of cards or just see
everything. They might want to see the most current card on top, or
pull in some historical cards. All of this is handled by overlay
component 494.
[0105] Reference is directed to FIG. 19, which is a software and
hardware integration architecture diagram for a wireless well
performance monitoring system according to an illustrative
embodiment of the present invention. In FIG. 19, the Data Streams
box 500 represents the protocol communications layer, or
"Comm-Mgmt". The Device Management box 502 represents the logical
devices layer of the protocol, or "Base-Mgmt". The Connectivity Box
504 represents the sensor data stream layer of the protocol, or
"Sensor-Mgmt". The separation of layers is significant for the DAQ
Service as it manages information flow between hardware and
software components in the system hierarchy. The DAQ service is
layered by responsibility, so that each layer has a specific
purpose. The architecture uses various messaging techniques for
communication between various layers within the DAQ Service. Since
each layer has its own processor thread, the communication must be
"thread-safe" and asynchronous in nature. The Comm-Mgmt Layer 500
sends a message to the Base Mgmt layer 502. When the Base Mgmt
layer 502 sees the message, it handles it and sends back a response
message. The Base Mgmt layer 502 can choose to deal with the
message at a time it chooses to and does not prevent the Comm-Mgmt
Layer 500 from continuing to do whatever it deems the highest
priority. In order to support this type of behavior a communication
"backbone" between the layers is established such that they can
pass messages to other layers including the Sensor Mgmt layer 504
as well as the user interface layer (not shown). This allows the
layers to communicate but remain independent in execution from each
other, and for the system to manage the processor time allocations
and priorities.
[0106] Thus it can be appreciated in FIG. 19, that the Connectivity
504 functions include the physical USB port and its software driver
508, which are typically native to the personal computer used as
the host processor. The Communication Management routine 506 of the
illustrative embodiment serves to organize packets, addressing, and
certain other hardware control functions, which are transferred
with the USB driver 508. The Device Management 502 functions can
transfers data with the Communications Management routine 506. The
wireless Base 512 physically connects to the USB interface 510, and
the two communicate within the constraints of the USB protocol. The
wireless base 512 communicates through its two transceiver with any
of plural wireless remote modules 514, 516. The radio
communications physical layer follows the IEEE 802.15.4 protocol in
transferring packet back and forth. On the host computer side of
the Device Management 502 functions, a Base Management 522 routine
controls communications with the virtual base 524, and the virtual
wireless modules 526, 528. The Base Management 522 routine is thus
unconcerned with the Connectivity 504 functions that support its
communications needs. Thus the Base Management 522 routine is
enabled to transfer data, commands, and controls with the wireless
base 512, and the wireless remote sensors 514, 616 though access to
the virtual machines 524, 526, 528, disregarding the layers of
communications that support the exchange.
[0107] The purpose of the Device Management 502 functions is to
support the system requirement to wirelessly communicate data,
commands, and controls between the various sensors 518, 529 and the
host software application software needs discussed with respect to
FIG. 18. This is managed in FIG. 19 by the Data Stream 500
functions. Plural sensors 518, 520 gather data through transducers
of various types, and this information is connected to a sensor
interface in the wireless remote modules as sensor signals. This
information is available to the Sensor Management 530 routine from
the virtual digital sensors 532, 534 as the samples data converted
in the Wireless Remote Modules 514, 516. Again, the Sensor
Management 530 routine is unconcerned with the layers of
communication implement in the illustrative embodiment, and simple
view the source as the local virtual sensors 532. Of course, not
all communications of information is fully end-to-end. Command,
set-up, control, and other function calls can be directed to the
various physical devices and software functions located throughout
the systems.
[0108] Reference is directed to FIG. 20, which is a system diagram
for a wireless well performance monitoring system according to an
illustrative embodiment of the present invention. This figure
presents one fundamental illustrative embodiment of the structural
arrangement of the functions and protocols. Plural wireless remotes
558, 560 gather information from a well fluid extraction process,
as well as provide for user inputs and system control outputs at
the well fluid extraction process. The wireless remotes 558, 560
communicate with the wireless base 554 using the system's base and
remote radio protocol 556. The protocol supports the transfer of
sensor signals from the wireless remotes 558, 560 to the base 554.
In addition, the radio protocol 556 supports the transfer of user
inputs and other system data, such as indentifies and calibration
information, from the wireless remotes 558, 560, to the base 554.
The radio protocol also supports the transfer of commands and data
from the base 554 to the wireless remotes 558, 560, including data
to write to a visual output, operating parameters, identifiers, and
calibration coefficients. The wireless base 554 communicates with a
host software application, here referred to as the TAM Application
550 using a processor and base command protocol 552, referred to
here as the PC/Base protocol 552. All of the aforementioned data,
including sensor signals, inputs, outputs, data, identifiers,
coefficients, and other information can be transferred between the
TAM Application 550 and the base 554 using the PC/Base protocol
552. The base 554 is also operable to provide and conduit function
for information flowing end-to-end between the TAM Application 550
and the wireless remotes 558, 560, and the base may function as a
protocol converter between the PC/Base protocol 552 and the
Baser/Remote protocol 556.
[0109] Reference is directed to FIG. 21, which is a sensor state
transition diagram for a wireless well performance monitoring
system according to an illustrative embodiment of the present
invention. In this illustrative embodiment, there is an emphasis on
power management, particular in the wireless remote sensor units
where long operating periods are desirable as well as compact
battery size. A sleep mode of operation is employed such that the
sensors wake up periodically to transmit a brief identity beacon,
and then go back to an ultra low power sleep mode. The sensor also
pauses for a moment to receive a reply command, should a base unit
respond to the beacon, to enter and more active operating state.
This can be accomplished within the constraints of the IEEE
802.15.4 radio hardware and protocol environment. This arrangement
is also facilitated by the fact that the wireless base typically
has a greater power reserve, in that it can draw power from the USB
port interface, or other power source. Thus, the base can remain
active to receive the spurious beacon signals from the several
remotes that may be in radio range. In the illustrative embodiment,
the sensors can be in one of four states, which include Off
(powered down) 562, Not Commissioned 564, Commissioned 566, and
Acquiring (actively sending sensor data).
[0110] The Off (powered-down) state 562 in FIG. 21 is the initial
state for a sensor. In this state, the radio and processor within
the sensor are turned off and it will not transmit a beacon or
respond to signals from the base in any way. In order to get out of
the Off state 562, a wake-up button on the wireless remote must be
pressed, which may be an On-Off actuator. Actuating the wake button
transitions the wireless remote into a Not Commissioned state 564.
This activates the wireless remote to it lowest power consumption
state, and in this state, the wireless remote has not yet been
bound to a corresponding wireless base unit. In the Not
Commissioned state 564, the sensor transmits a periodic identifying
radio beacon, and will also wait briefly for a reply after each
beacon. The wireless remote will also respond to a reply requests
from any wireless base unit. It is significant to note that any
wireless remote can operate with any wireless base through
utilization of the beaconing and response processes. Once a base
unit responds to the wireless unit beacon, the two become paired to
operate together, at which time the remote is no longer responsive
to commands from non-paired wireless bases. In a typical scenario,
the reply from a wireless base will be a commission request
indicating the identity of the wireless base. Thus, when a wireless
remote receives a request from a wireless base to commission, the
wireless remote will respond and become attached to that base, each
recognizing the other by an identifier in the subsequent
transmissions of packets. Periodic transmissions back and forth
maintain the duration of the "attached" relationship. If the sensor
has not received a message from a base after a specified timeout
period, the sensor will reduce the rate at which it transmits
beacons to a slower and slower rate until it reverts to a sleep
state to conserve battery life. All of the foregoing beacons and
transmissions occur on a default configuration channel in the 2.4
GHz IEEE 802.15.4 transceiver.
[0111] Continuing in FIG. 21, after receiving a commission request,
the wireless remote enter the Commissioned state 566 and becomes
bound to the wireless base. The wireless remote continues to
transmits identity beacons, but at a faster rate, thus becoming
more responsive to wireless base requests, but with the side effect
of higher power consumption. Both the slow and fast beacon rates
are programmable by the host software application in the
illustrative embodiment. In the Commissioned state 566, the
wireless remote is only responsive to requests from the attached
base containing the requisite base identity, and will ignore
requests for any other wireless base. After a predetermined and
programmable timeout period of not receiving any requests from its
attached wireless base, the sensor will revert to the Not
Commissioned state 564. The transition to the Acquiring state 568
occurs upon receipt of a start command, which can be sent by the
wireless base on command from the host software application.
[0112] Within the Acquiring state 568 in FIG. 21, the wireless
remote is actively receiving sensor data, digitally sampling it,
and sending packets of sampled data to the wireless base. Note that
transition to the Acquiring state 568 typically includes a retuning
of the transceiver in the wireless remote to a data channel in the
IEEE 802.15.4 transceiver. This is done so that the second
transceiver on the wireless base can remain active on the
configuration radio channel to communicate with other wireless
remotes. The sensor will remain in the Acquiring state 568 until it
receives a stop command from the base, or until it fails to receive
synchronization pulse from the wireless base. The synchronization
pulse are broadcast by the wireless base at precise timing
intervals, and serve as a timing reference to the digital sampling
process. As has been discussed, the synchronization of sampling is
important because it enables all of the plural sensors active in a
give test process to report sensor data at the same instant in
time. For example, the dynamometer readings include both force and
acceleration, and these two values ultimately determine Cartesian
plot data points on the dynagraph. If they are not precisely
synchronized, then the dynagraph will appear distorted and
irrational on close inspection. Similarly, pressure, temperatures,
motor drive samples and even liquid level readings benefit from the
precise synchronization made possible by the wireless base
synchronization pulses.
[0113] Further in FIG. 21, note that the transitions to increasing
levels of activity from Off 562 to Not Commissioned 564 to
Commissioned 566 to Acquiring 568 each occur as a result of an
intentional action by the user or a software command dictating an
increased level of functionality. Similarly, the reverse of
transitioning back down to lower levels of activity can occur by
intentional action or command. However, it should be noted that
since the radio link cannot be completely reliable, the system is
designed to revert to lower levels of activity, and hence
safeguards battery power by employing timeout periods whereby the
sensor automatically reverts to the lower power state when expected
synch pulses or replies are not received when expected. Similarly,
the wireless base will decommission a wireless remote if it does
not provide the expected signal in a predetermined time period.
[0114] Reference is directed to FIG. 22, which is a sensor state
transition diagram for the Not Commissioned state in a wireless
well performance monitoring system according to an illustrative
embodiment of the present invention. This figure examines the Not
Commissioned state 564 in further detail. Beginning in the Off
state 561, the wireless remote powers up 572 either in response to
an internal wake-up command or from the user actuating a start
actuator on the wireless remote, which may be the On/Off or Acquire
actuators in the illustrious embodiment. During the Not
Commissioned state 564, the wireless remote's primary function is
to transmit identity beacons and then listen briefly for responses.
During the Off state 562, the wireless remote enters a low power
mode to conserve battery life. After sleeping, the sensor wakes up
572 and then transmits and identity beacon 574. The identity beacon
574 is a broadcast packet that the wireless remote sends to let all
wireless bases know that it is out there, and can be commissioned
for use. After sending a beacon 574, the wireless remote will
listen 576 for a predetermined period of time. If it does not
receive a response from a wireless base, it will power off 578
until it is time to beacon again. If the sensor receives a base
response in the Listen state 576, it will process the response 580
and respond to the wireless base that responded, and become
commissioned thereto. A request from the base to change state to
commissioned will cause the wireless remote to go to the
Commissioned state. After processing a request from any base, the
wireless remote will automatically go back to the Listening state
576 to check for another request before powering down. The
listening period and timeout is determined by the firmware and
timeouts.
[0115] Reference is directed to FIG. 23, which is a wireless remote
state transition diagram for a wireless well performance monitoring
system according to an illustrative embodiment of the present
invention. This figure illustrates further detail with respect to
the Acquiring state 568. In the Acquiring state 568, the wireless
remote will start transmitting data to the wireless base in a
continuous manner. This state is entered upon receipt of a Start
command. Once in the Acquire state, the wireless remote listens for
a synchronization pulse from the wireless base, which may contain
other commands, and it does this by monitoring its radio receiver.
When a synch is received, the wireless remote recognizes this as a
precise timing reference and immediately transitions to Acquire
mode 602. It then begins clocking its analog to digital converter
to Get Data 604 from its sensor interface, and packetizes and
Transmits 608 the data through the radio protocol to the wireless
base. This process repeats at the predetermined sampling rate,
which may be 30 Hz in the illustrative embodiment. Since the rate a
which synch pulse are received is a predetermined interval, the
wireless remote knows when it is time for each subsequent synch
pulse to arrive and it reverts to the Synch mode 600 to listen for
the next synch pulse. The synch pulse again aligns the precise
timing of the sampling process, and it repeats indefinitely until
one of two events occurs. The first event is the presence of a Stop
command from the wireless base, transmitted within the synch pulse.
If this is received, the wireless remote stops acquiring and
returns to the Commissioned state. The second event is when the
wireless remote returns to the Synch mode 600 to await the next
synch pulse, but it is not received within a predetermined Timeout
interval. In this case, the wireless remote has lost contact with
its base so it is decommissioned to the Not Commissioned state, and
begins to transmit periodic beacons.
[0116] Reference is directed to FIG. 24, which is a data timing
diagram for a wireless well performance monitoring system according
to an illustrative embodiment of the present invention. This figure
illustrates the data packet transmission timing relationship for
the communications between a wireless base unit and two wireless
remote units. Since the IEEE 802.15.4 transceivers are duplex, the
system is capable of simultaneous two-way communications. However,
it will be appreciated that issues related to receiver sensitivity
in view of an adjacent transmitter need to be addressed in the
protocol in order to provide avoid receiver desensitization and
maintain optimum system performance. This is part of the reason
that the illustrative embodiment multiplexes packet and transmitter
operation over time. Another reason is that the system allows
plural wireless remotes to transmit on the same frequency to the
same wireless base unit, and therefore each is allocated specific
time periods for transmission. A further reason is that the
wireless base in the illustrative embodiment includes two
transceivers, and it is important to time data communications so
that the two separate radios do not interfere with one another.
This is accomplished by sharing a common sync pulse between the two
base transmitters so that all of the wireless remotes operating on
both base transceivers are precisely synchronized. This arrangement
also assures that all of the collected data samples are
synchronized in time, and presented in a coherent manner all
through the host computer processing and display functionality.
Thus, it can be appreciated that controlled timing is essential to
reliable system performance. In FIG. 24, a wireless base transmits
and receives along data frame line 608. A first wireless remote
transmits and receives along data frame line 610, and a second
wireless remote transmits and receives along data frame line 612.
Time is display along the horizontal, and is divided into frames at
frame lines 618. Each Frame begins with the wireless base sync
pulse 619 transmission.
[0117] In considering FIG. 24, it should be noted that in the
Acquisition mode, the wireless remote communicates with the
wireless base differently than when in the beaconing mode. Time is
broken into frames (Frame 1, 2 and 3 in FIG. 24) and then each
frame is broken into multiple time slots, whose duration and timing
are programmable by the host software application depending on the
number wireless remotes and the number of sensor connected to each
remote. During configuration, the wireless remotes are programmed
by the host application through the wireless base as to which time
slots they are assigned to send data to the base, and during which
time slots they need to listen for the base to send requests. Also,
during acquisition, the base does not send commands or set the
state of the wireless remote LED indicators like it does when the
wireless remote is beaconing. Rather, the base interleaves commands
during the time slot that is allotted for the base to send sync or
stop commands. The wireless remote listens for sync, stop, or other
commands during the time slot allotted for the base to send
commands. This enables the system to continuously update the
wireless remote LED indicator state even while acquisition mode is
running. Furthermore, in the Acquisition state the wireless remote
cannot respond to requests from the wireless base about its status.
In order to monitor the performance of the wireless remote, status
information is interleaved with transmitted data during
acquisition. This requires the wireless remote to regularly insert
an "info" packet into the stream of "data" packets that are being
broadcast during its time slots. The information in the "info"
packet includes key actuations, so that the wires base can be
responsive to user inputs during the Acquiring mode. The wireless
remote inserts the info packet at the beginning of its first slot
for each frame.
[0118] The wireless base timing line 608 consists of repeating
frames that begin at frame lines 618 with the synchronization
pulse, or `sync` pulse. As has been discussed, the sync pulse sets
the timing reference for various components and timing functions in
the system protocol. Sync is used as a reference for the remotes to
time their respective transmission slots, and it is used as a
timing reference for the exact instance the sampling converters are
clocked, as well as a reference for the sampling frequency. In
timing line 608, the sync transmission time period for the wireless
base is followed by a period for listening (transceiver is in
receive mode) to the several wireless remotes, which is referred to
as listening for data. Again, note that the time periods and frame
lengths are a programmable feature of the illustrative embodiment
radio protocol. The sync transmission period 614 then repeats at
the beginning of each data frame. The sync transmission period 614
actually includes plural data slots used for various purposes. The
synchronization signal 916 leads the frame, and is repeated in
every sync period 614. There are also command transmission frames
for information and requests from the remotes. Remote specific
commands can be sent to remote one 620 and remote two 622, or
however many remotes are currently engaged in the radio protocol.
These are commands that do or request specific things, such as
controlling the state of the remote's indicators, requesting data
such as calibration information, battery life, temperature and so
forth. There is also a global command slot 624 in the sync period
614 for sending common commands to all the remotes, such as the
Stop acquisition mode command. Following the sync period
transmission 614, the wireless base listens with its receiver for
the remainder of each frame.
[0119] In FIG. 24, each remote also has a data timing line, line
610 for wireless remote one and line 612 for wireless remote two.
As the wireless base is configured for a specific data acquisition
session, the host software application has the number of wireless
remotes, the number and type of sensors connected to each, and the
data sampling rates for each. The host software application then
calculates the data throughput required for each, and assembles a
suitable data framing arrangement for each remote. These include
the frequency at which sync pulses are transmitted, which defines
the frame duration, and groups of data slots with predetermined
durations and start time offsets from the sync pulse. In the
illustrative embodiment, sync repetition times range from 100 ms to
1 second. The overall duration of the frame periods are determined
as well. This information is passed off to the remotes during a
pre-acquisition configuration period. FIG. 24 illustrates a useful
configuration for two wireless remotes. All of the remotes 610, 612
listen at the beginning of each frame for the duration of the sync
period 614, and set their internal timing references as well as
decoding and responding to commands sent by the base. The wireless
remote transmission period 616 of each frame is divided into six
data slots in this example, three for wireless remote one, and
three for wireless remote two. Each remote is assigned an offset
time to begin its data transmission and a duration during which it
can transmit. The data transmission period 617 for remote two is
magnified in FIG. 24 to show further details. The beginning of the
first data slot from Remote 2 contains an information packet 626,
which is were the remote responds to commands from the base or
provides other system data during the acquisition process. The
remaining data slots contain packets of sampled data 628 from the
digital converters connected to the transducers. Each data packet
is framed according to the radio protocol with source and
destination addressing used to route information through the
aforementioned communications layers. In addition, there is
typically excess data transmissions space in the assigned data
slots, and the remote can use this to retransmit packets that were
received with errors, where the base made a prior request that they
be retransmitted. The requests for retransmission follow an error
detection process and are transmitted in the base sync periods 620,
622 in this embodiment.
[0120] Thus, the present invention has been described herein with
reference to a particular embodiment for a particular application.
Those having ordinary skill in the art and access to the present
teachings will recognize additional modifications, applications and
embodiments within the scope thereof.
[0121] It is therefore intended by the appended claims to cover any
and all such applications, modifications and embodiments within the
scope of the present invention.
* * * * *