Note: Descriptions are shown in the official language in which they were submitted.
CA 02404625 2002-10-18
SYSTEM FOR ACQUIRING DATA FROM A FACILITY AND METHOD
BACKGROUND OF THE INVENTION
This application is a division of Canadian Patent Application Serial No.
2,314,573, filed
20 July 2000.
This invention relates to a system for obtaining pressure, flow and
temperature data from
a facility. More particularly, but not by way of limitation, the invention
relates to an instrument
and system that collects, processes and stores measurements of pressure, flow
and temperature
and relays data to many users.
In the production of oil and gas from subterranean reservoirs, operators have
found it
necessary to complete wells in many remote regions. In order to produce,
transport and refine
hydrocarbons, it is necessary to construct production facilities at these
remote regions. Due to
the hazardous nature of hydrocarbons, it is necessary to employ various safety
features in all
phases of the process to ensure against pollution, explosion, and other safety
hazards.
Operators find it beneficial, if not necessary, to monitor pressure,
temperature, flow
rates, etc from these oil and gas facilities. The reasons for monitoring are
numerous. For
instance, the operator may wish to test the producing well in order to
calculate bottom hole
pressure, permeability, skin damage, etc. Additionally, the operator may
simply wish to monitor
the pressure within separators, pipelines and/or vessels to maintain proper
working conditions.
Regardless of the specific application, there is a need to accurately monitor
conditions at the oil
and gas facility in a timely manner.
Prior art devices have been designed to remotely communicate with oil and gas
facilities.
For instance, Supervisory Control And Data Acquisition (SCADA) systems have
been developed
to monitor and communicate with these remote areas. However, these SCADA
systems suffer
1
CA 02404625 2002-10-18
I from a variety of deficiencies.
2 A significant deficiency is related to the inherent limitations of the
Master-Slave
3 communication protocol that is employed by SCADA systems.. Further, prior
art systems
4 communicate from a limited number of oil and gas facilities to a single
monitoring station which in
turn relays information to a central control station. This architecture is
necessary since the Master
6 monitoring station must poll each Slave Field location individually to
prevent communication
7 collisions.
8 Another limitation in current practice is the accuracy of pressure
measurement which is
9 impaired by ambient temperature fluctuations. This accuracy limitation
reduces the effectiveness
in many process monitoring applications that depend on measurement stability,
such as process
11 simulation or process accounting.
12 A further limitation of current practice is the elaborate installation
requirements that result
13 from the physical size, number of components and complex interconnections
that are needed to
14 implement each field location with a remote measurement system.
Therefore, there is a need for a system and method that can capture, store and
process
16 accurate pressure, flow and temperature data, and communicate this data in
a more flexible
17 manner to a local computer and/or remote server. There is also a need for a
system that will
18 allow for users to access data from multiple remote locations on an as
needed basis. Further,
19 there is a need for a system that can alert remote users of predetermined
alarm conditions in an
efficient and timely manner. There is also a need in many practical
applications for improved
21 pressure measurement accuracy and stability compared to what is achieved
using current practice.
22 There is also a need for an instrument that can work in an oil and gas
environment without fear of
2
CA 02404625 2002-10-18
1 explosion. There is also a need for an instrument that integrates many of
the measurement system
2 components into a single, compact package to simplify installation. These,
and many other needs,
3 will be accomplished by the invention herein described.
4
6 SUMMARY OF THE INVENTION
7
8 A system for transmitting a pressure reading obtained from a process line is
disclosed.
9 The system comprises a small, explosion proof enclosure having a first
opening with a first
integrated analog pressure sensor therein which is connected to control means
for receiving,
11 processing and storing the digital pressure output reading. The control
means is located within
_12 the enclosure. A second remote digital sensor is connected to the control
means via a second
13 opening within the enclosure. The system may further comprise means,
positioned within the
14 internal chamber, for transmitting the digital pressure output reading to a
remote location. The
system also contains serial communication means for transmitting the processed
digital pressure
16 output readings to a terminal located at the facility.
17 In one of the embodiments, the system includes database means, operatively
associated
18 with the transmitting means, for storing the digital readings with the
database means including a
19 data manager means for receiving, retrieving and communicating the digital
readings. The system
may further comprise a central server, located remotely from the facility, and
wherein the central
21 server is capable of receiving the data.
22 The system may further comprise user interface means, operatively
associated with the
3
CA 02404625 2002-10-18 ...
1 database means, for allowing access to the data, and a user computer having
means for accessing
2 the user interface means.
3 The system further comprises a plurality of analog sensors producing an
analog signal; an
4 adapter connected to the analog sensor, with the adapter being sealingly
received within a second
opening in the enclosure; and means, electrically connected to the analog
sensor, for converting
6 the analog signals to digital readings.
7 In one of the embodiments, the transmitting means comprises a communications
module
8 means for transmitting the digital pressure output reading using a TCP/II'
protocol to a central
9 server via the Internet. The system may further include a user computer, and
wherein the user
computer has loaded thereon a web browser capable of reading the data and a
communications
11 link from the user computer to the Internet.
12 A process for collecting, transmitting and monitoring a pressure from a
facility is also
13 disclosed. The process comprises communicating the pressure to a tubular
member and
14 communicating the pressure from the tubular member to a pressure sensor. An
enclosure is
provided, with the enclosure having a first opening, a second opening, and an
inner chamber, and
16 wherein the pressure sensor is housed in the first opening.
17 The process includes sealing the first opening and the second opening so
that the pressure
18 is withheld from the inner chamber so that the pressure is precluded from
entering or exiting the
19 inner chamber. A digital pressure reading from the pressure sensor is
collected and transferred to
a control means for receiving, processing, and storing the digital pressure
reading, and wherein
21 the control means is located within the inner chamber. Next, the digital
pressure reading in the
22 storage means is transferred to a modem communications means for
communicating digital data,
4
CA 02404625 2002-10-18
1 and wherein the modem communications means is located within the inner
chamber.
2 In one of the embodiments, the digital pressure reading is converted to a
digital packet
3 data in the modem communications means which in turn is transmitted via the
modem
4 communications means. The digital packet data is received at a remote data
base engine where it
is stored for later retrieval. The process may further comprise collecting an
analog reading with
6 an analog sensor, and wherein the analog sensor is sealingly housed within
the second opening of
7 the enclosure. The analog reading is converted to a digital reading and is
transmitted to the
8 control means.
9 In one of the embodiments, the data base engine contains a data manager and
the method
further comprises storing the digital pressure data and digital temperature
data. Additionally, the
11 database engine may further contain'a central server interface and the
process further comprises
12 providing a central server communica.ted with the database engine via the
central server interface
13 and accessing the central server from a user computer. Next, the digital
pressure reading is
14 requested from the user computer and the digital pressure reading is
transmitted to the central
server which is ultimately transmitted to the user computer.
16 According to the teachings of the present invention, it is also possible
for a user computer
17 to have a direct link to the control means. The user computer could be
located at the facility or at
18 a remote facility. The process would comprise connecting with the control
means from the user
19 computer with the direct link, and transmitting the digital pressure
reading to the user computer.
In another embodiment, the process includes polling the field instruments data
and setting
21 predetermined data limits. Once a predetermined limit is exceeded, this
exception will be
22 recorded, and an exception signal is produced. The exception signal is sent
to the database. The
5
CA 02404625 2002-10-18
1 exception signal is transmitted to the central server and then transmitted
to the user computer.
2 The process may also include sending the digital pressure data to a web
server and then
3 sending the digital pressure data to the Internet Wherein the digital
pressure data may be accessed
4 over the Internet with a web browser from a user computer.
In one of the preferred embodiments, the step of correcting the digital
pressure data for
6 ambient temperature effect corruption includes mapping the digital pressure
data through iteration
7 and back calculating to a high accuracy pressure reading.
8
9 A feature of the present system includes allowing for routine and unattended
measurements, data logging and compression and data base generation locally
and remotely. It is
11 possible for long term process performance monitoring, on-board
configurable process analysis
12 (i.e. report when a process parameter reaches a certain value), and process
monitoring and
13 indica.tion.
14 The operatmg system has incorporated therein orifice gas flow AGA 3 or AGA
8
calculations, process excursion reporting and time stamping (i.e. for peak
demand billing), and
16 warning generation and error logging (i.e. for process interlocks and
diagnostics). The operating
17 system performs sampling at rates fixed, programmed sequences, or are
triggered and/or auto
18 adjusting. The sampling rate may be based on a pressure set point (rise and
fall), the rate of
19 pressure change (rise and fall), the pressure differential (rise and fall),
a temperature set point (rise
and fall), and the rate of temperature change (rise and fall).
21 The sampling rate may also be based upon calculated parameters such as flow
rate (i.e.
22 high flow, high sample rate), rate of flow rate change (i.e. steady flow,
low sample rate, erratic
6
CA 02404625 2002-10-18
1 flow, high sample rate). It is possible to have a sample rate related to the
state, the change of
2 state, the period or the rate of a digital input signal. Another feature is
the ability to perform
3 dynamic and/or static source characterization that includes in-line testing
for pipelines, pumping
4 stations, tank farms, etc that need transfer function characterization as
well as well testing. For
instance, the instrument can be used with shut-in tools to develop "Pressure
vs. Time ' and
6 "Pressure vs. Flow Rate" characteristic curves for reservoir analysis. The
system can also be used
7 for preventive maintenance reminders and system error detection and
flagging.
8 Data transfer and alarm notification capability of this system is
significantly more flexible
9 than prior art devices because of the use of TCP/IP protocol. The system
will also allow long
term data logging and storing of this data. Perhaps most importantly, these
instruments have high
11 accuracy, high precision and high resolution af pressure data which is
essential for proper
12 management and optimization of oi1 and gas production and transport
facilities.
13 With reference to external communications, the system allows for
communications port
14 management. Additionaily, the wireless modem option allows for access to
dedicated or local
public phone systems or satellite access for very remote locations, which in
turn allows access to
16 the Internet or local intranet. The instrument data is in a standard format
and the instrument uses
17 standard communication protocols, and standard communications channels. The
instrument can
18 use either an integrated or remote antenna.
19 The system data management and data routing features may be configured in
various
ways. The simplest is a one-to-one relationship where data from one instrument
is conveyed to a
21 single user. Instrument and data access is managed by a single user.
Second, it is possible to have
22 data collected from many instruments collated and conveyed to a single
user. Instrument and data
7 %
CA 02404625 2002-10-18
1 access is managed by a single user. Third, data from many instruments is
collected, collated, and
2 conveyed to a variety of users. Instrument and data access and control
privileges are managed by
3 a localized or distributed process and may be different for different users.
4 An onsite user has a local display and indicators that include liquid
crystal display (LCD)
for presenting measurement results, error codes and message; a light emitting
diode (LED) noting
6 instrument status and a power LED. Manual input switches are included for
master reset and
7 system configuration. Also, the local terminal option allows for running
local diagnostics, install
8 firmware upgrades and possible local retrieval of process data.
9 Another instrument feature is that it is compact, relatively self contained,
and highly
integrated. The endlosure can be used in hazardous locations ( it is explosion
proof, and rated for
11 Zone 1). The enclosure is physically rugged and environmentally sealed.
12 A.pplica.tions include fluid or gas metering, typically in remote
processing facilities or
13 pipelines. The field instruments are comparatively low cost and easy to
install. Few changes are
14 required to existing facilities.
The system can monitor pressure and flow rate when the instruments are
combined with
16 orifice plates. The operating system can instruct the instrument to sample
data at rates of up to
17 once per second to enable high temporal resolution flow calculations to be
performed. The
18 instrument is suitable for custody transfer applications, point-of-use
metering, and transmission
19 pipeline leak checking. The instrument normally acts in a remote data dump
mode to periodically
deliver logged flow data and flow statistics to a user's database via a
wireless digital modem. If
21 required, the instrument can switch into an alarm mode to proactively
signal that a process
22 variable or state is out of specification or it can be periodically
interrogated to read process
8
CA 02404625 2008-05-30
conditions. The location of the device may be the well head, pipeline
monitoring station etc.
Generally, communication will be over a wireless communication channel
provided either by a
terrestrial cellular service or a digital satellite link. The novel instrument
can be used in remote
and/or unattended settings or when accurate collection and time stamping of
flow rate and
totalized volume is required.
The system has multiple uses. For instance, the system can be used on oil and
gas
platforms, pipeline and pipeline facilities. The system can be used to monitor
water
production and water table levels. The novel systems can be used for custody
transfers, or for
monitoring storage and distribution facilities, chemical processing
facilities, bulk transfer
facilities (trucks, ships, rail cars, etc.) Additionally, the field
instruments may be used on
point of use systems and utilities including water and sewer.
In one aspect of the invention there is provided a method of measuring a
reading at a
remote location on a hydrocarbon process line, the method comprising: at said
remote
location collecting a first analog reading with a first sensor; converting the
first analog
reading to a first digital reading; collecting the first digital reading from
said first sensor in a
control means for receiving, processing, and storing the digital readings,
wherein said control
means is located at said remote location; storing the digital readings at the
remote location until
the digital readings can be transfered to a modem communications means for
communicating
digital data, wherein said modem communications means is located at said
remote location;
converting the digital readings to a digital packet data in the modem
communications means;
transmitting the digital packet data with the modem communications means; at a
central
location remote from the remote location receiving the digital packet data at
a database
engine located at the central location; providing a web server interface in
the database
9
CA 02404625 2008-05-30
or
engine; linking the database engine to the Internet; providing a user
computer,
said user computer having a web browser; communicating to the Internet;
accessing the
database engine; monitoring measurements from a user computer.
In a further aspect of the invention there is provided a system for
transmitting a
pressure reading obtained from a remote oil and gas facility, said oil and gas
facility having a
pressure, the system comprising: at least one field instrument located at said
remote oil
and gas facility including a digital sensor means, for producing a
representative first digital
output reading; an analog pressure sensor means, for producing a
representative analog
pressure output reading; means, electrically connected to said analog pressure
sensor means, for
converting the analog pressure output reading into a second digital output
reading; means,
for receiving and storing said first and second digital output readings;
means, electrically
connected to said receiving and storing means, for locally accessing said
first and second
digital output readings; means, for transmitting said first and second digital
output readings;
database means located at a central location distant from the remote oil and
gas facility,
operatively associated with said transmitting means, for storing said first
and second
digital output readings in a plurality of data tables, said database means
including a data
manager means for receiving, retrieving and communicating said digital
pressure output
readings.
In yet a further aspect of the invention there is provided a process for
collecting,
transmitting and monitoring sensed characteristics from a remotely located
facility, the process
comprising: at said remotely located facility, sensing a sensed reading
indicative of a
cllaracteristic of said facility by way of an analog sensor; converting the
analog sensor
9a
CA 02404625 2008-05-30
reading to a first digital reading; collecting the first digital reading;
collecting a second
digital reading with an external digital sensor; transmitting the second
digital reading to a
control means; transferring the digital readings to said control means for
receiving, processing,
and storing the digital readings in a storage means; transferring the digital
readings in said
storage means to a modem communications means for communicating digital data,
wherein
said modem communications means is located at said remotely located facility;
converting the
digital readings to a digital packet data in the modem communications means;
transmitting the
digital packet data with the modem communications means; receiving the digital
packet
data at a data base engine at a central location remote from the remote
location located at the
central location.
BRIEF DESCRIPTION OF THIS DRAWINGS
Figure I is a schematic flow chart of the basic components of the surface data
system.
Figure 2 is a cross-sectional view of a pressure data probe embodiment.
Figure 3 is a schematic diagram of the hardware configuration of the preferred
embodiment.
Figure 4 is a schematic flow chart of a first systems architecture of the
present invention.
Figure 5 is a schematic flow chart of a second systems architecture of the
present invention.
Figure 6 is schematic diagram of one embodiment of the server arrangement.
9b
CA 02404625 2002-10-18
1 Figure 7 is a flow chart of the digital signal processing of the present
invention.
2 Figure 8 is a flow chart of the analog signal processing of the present
invention.
3 Figure 9 is a flow chart of the sequence of powering the sensors in order to
take readings.
4 Figure 10 is a schematic illustration of an enclosure of the present
invention.
Figure 11 is an operations and data flow chart of the preferred embodiment
6
7
8 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
9
Referring now to Fig. 1, a schematic flow chart depicting the basic components
of the field
11 instrument 2 (FI) of the present invention will now be described. The FI 2
is a very high accuracy
12 pressure instrument designed specifically for use in the oil and gas
industry. In the embodiment
13 shown, two analog pressure sensors 4.& will be included within the
enclosure.
14 The sensor core is a high accuracy, silicon crystal, strain gauge which has
been laser
welded into a high pressure autoclave fitting adapter, which in turn is
threaded into one of the
16 housing ports located on the enclosure. This sub-assembly is rated for
pressures up to 12,000 psi,
17 and has an over-pressure rating of 1.3. Suitable pressure sensors 4, 6 are
commercially available
18 from Z. I. Probes, Inc. located in Canada under the mark # 14095140
Pressure Sensor.
19 An auxiliary analog sensor port is included in the enclosure to attach to a
low accuracy
external resistive based sensor 8, such as a temperature probe. Temperature
probes are
21 commercially available from Omega, Inc. under the name PR-12 Type. The FI 2
may also
22 incorporate an auxiliary digital sensor port Q so that the device may
attach to communicate to a
CA 02404625 2002-10-18
1 number of external digital sensors over a RS-485 signaled bus. On this bus,
the Fl 2 will poll
2 external digital sensors using various protocols (i.e. Mod-bus). The
enclosure of the Fl 2 is
3 explosion proof, and will be C.S.A./UL certified for operation in Zone
1(Class 1, Div 1, Group
4 C, D, etc) hazardous locations. The actual enclosure will be described later
in the application.
In the preferred embodiment, the Fl 2 is self-powered by an internal battery
pack 10, even
6 though the teachings of the present invention include use of a possible
external power source. A
7 rechargeable battery may be used. The rechargeable pack may be replenished
by connecting a
8 solar panel or with an externally powered charger as is understood by those
of ordinary skill in the
9 art.
Readings are acquired on a preprogrammed time interval via a custom operating
system
11 12 and stored internally in non-volatile memory14. Between readings, the
electronics and
12 sensors are powered off to conserve energy via a preprogrammed routine in
the operating system
13 12. The custom operating system utilizes a Real Time Clock (RTC). This RTC
powers up the
14 system at the preprogrammed time and then interrupts the main processor 1-6
in preparation for
acquiring each new reading. Once the electronics have been initialized, the
processor 16 will
16 acquire readings from each of the internal sensors 4, 6 and external
sensors 8, 9 connected to it,
17 and store these readings in non-volatile memory 12. The operating system
12, memory 14 and
18 micro-processor 16 are referred to as the control means for receiving,
processing and storing the
19 data.
Once the readings are processed, they will be optionally displayed on a small
LCD 1$ that
21 can be viewed through a window in the explosion proof enclosure as will be
described in greater
22 detail later in the application. Alongside the LCD 18 there are also
several small switches on the
11
CA 02404625 2002-10-18
I circuit board (not shown) to start an existing program, to reset the
processor 16, and to manually
2 configure the Fl.
3 As will be detailed later in the application, the Fl 2 can be utilized to
measure a variety of
4 process points. For instance, the system can be used for the following: to
measure a single
pressure and single temperature; to measure two pressures and a temperature;
to measure orifice
6 gas flow (which would require measuring a differential pressure) and a
temperature. This list is
7 illustrative.
8 In one of the embodiments disclosed, the Fl 2 can be used in the well-
testing market.
9 Thus, the invention allows for the monitoring of a pressure build-up test. A
line communicating a
pressure from any specific well can be communicated with the pressure sensor 4
which will allow
11 for the recording and transmission of data. The FI 2 can be instaUed onto a
well head or pipeline
12 for a short term test or for a long term test. The readings thus collected
may be stored in the non-
13 volatile memory 14 or communica.ted by one of the other described
communication means.
14 One of the advantages of the present system is the multitude of different
operation modes.
One mode would allow the readings to be downloaded to an on-site computer
after a test, such as
16 a standard laptop computer where they are viewed and a report is generated.
This mode of
17 operation is termed "Memory" only.
18 According to the teachings of the present invention, the FI 2 has also been
designed with
19 an internal wireless communications module 2-0. In the preferred
embodiment, the
communications module 20 is commercially available from Sierra Wireless Inc.
under the mark
21 SB300. Field units with the communications module 20 require external power
of about 3 Watts,
22 which will recharge the battery 10.
12
CA 02404625 2002-10-18
I Once installed on the test site, the SDS 2 will be self-contained and may be
left for long
2 periods at that location. In the mode of operation utilizing the wireless
communications module,
3 the FI 2 can relay process information on demand from the host server, on a
regular schedule or
4 by exception reporting (i.e. exceeding an alarm threshold which will be
described later in the
application). Once the raw readings of the sensors 4, 6, 8, 9 are acquired,
these readings are
6 converted to process values. This is done using an algorithm and a
calibration (CAL) file.
7 The module 20 that has been packaged into the FI 2 is a low power device
that allows
8 computer to computer communication by four means, namely: (1) land-line
phone; (2) circuit
9 switched cellular channel (i.e. it works on first generation analog cell
phone channel); (3) cellular
digital packet data (CDPD); and, (4) satellite (i.e. data may be transmitted
by utilizing low power
11 satellite communications). These four standard means of communication allow
the FI 2 to be
12 located wherever there is adequate cell phone coverage or a land line
connection.
13 In one of the embodiments, the operating system 12 in conjunction with the
14 communications module 20 will allow the FI system to utilize the
Transmission Control
ProtocoVInternet Protocol (TCP/IP) for all communications with the network
architecture for all
16 operations including, but not limited to, well testing and monitoring
applications.
17 TCP\IP is a major communication protocol standard. TCP/IP is actually two
separate
18 communications of protocols working in conjunction. An entire family of
related protocols is
19 covered in the TCP\IP heading, with TCP and IP as the two main protocols.
TCP is partly
responsible for breaking data down into packets, as well as reassembling them.
The IP part
21 handles how the data packets are transmitted over the network. By using
TCPUP, different
22 computers running in different operating systems can communicate with one
another if they all
13
CA 02404625 2002-10-18
t obey this protocol.
2 As those of ordinary skill in the art will appreciate, the field level
Supervisory Control And
3 Data Acquisition (SCADA) systems use a master-slave based communications
protocol (e.g.
4 Modbus). In most field monitoring situations, the remote office computer is
typically the Master
and the field unit is the Slave. This inherently deternunes how data flows
from the field unit back
6 to the office because the Slave can only transfer information to the Host
when it is polled. This
7 means that a field unit cannot initiate a notice to the central office when
it has an alarm condition.
8 Using the TCP/IP protocol removes this Master-Slave relationship and allows
information
9 to flow asynchronously between the field unit and the central office. This
novel system includes
the following advantages over the prior art: first, the field unit can notify
the central office
11 whenever there is an exception or alarm condition without waiting for the
host to poll for it;
12 second, packet based transmission over the wireless network removes the
possibility where the
13 field unit radio may malfunction and jam the transmission link for alI
other units in the line of sight
14 area; third, FI units may be activated to take simultaneous readings on an
array of sites. This list
was meant to be illustrative.
16 Referring now to Fig. 2, a schematic illustration of a basic pressure
sensor 4 will now be
17 discussed. It should be noted that like numbers in the various figures
refer to like components.
18 Generally, semiconductor pressure transducers are conunercialiy available
from companies such as
19 National Semiconductor, Motorola, and Honeywell. The pressure sensor 4 of
the preferred
embodiment has been modified by applying a temperature correction factor
algorithm into the
21 operating system, with the pressure sensor 4 of the preferred embodiment
being commercially
22 available from Z. I. Probes, Inc., as mentioned earlier.
14
CA 02404625 2002-10-18
I In one of the embodiments, the sensor 4 consist generally of a flexible
silicon diaphragm
2 30 with resistive bridge sensors 32 mounted on the surface. One side of the
diaphragm faces a
3 sealed chamber 34 while the other side is made open to an input pressure.
Deflection of the
4 diaphragm in turn causes the resistive sensors to produce a signal as is
well known in the art. All
of the necessary electronic circuitry 11 including the bridge circuit,
excitation, instrumentation
6 amplifiers, and other compensation and conditioning circuitry is included.
7 Figure 3, which is a schematic diagram of the hardware configuration of the
preferred
8 embodiment, will now be described. The power management means 50 includes an
internal
9 rechargeable cel152, which in the preferred embodiment is a Li based
rechargeable battery. This
battery 52 is suitable for an ambient temperature range of -20 degrees C to
+50 degrees C. Some
11 of the features of the power management means 50 will also include battery
protection circuits
12 (not shown) which allows for low voltage shut down which protects the
battery from deep
13 discharge degradation effects. Also included will be a high voltage clamp
that protects the battery
14 from overcharge. Also included in the power management means 50 are
circuits for battery
cycling and conditioning that ensure that the batteries do not remain at peak
charge voltage for
16 extended periods. Smart charger technology is also included that is
configurable to allow changes
17 for new battery technology.
18 As seen in Fig. 3, the hardware configuration also includes external power
options. An
19 optional solar panel connection 54 may be included. The design also allows
for an optional
battery bank 56 to be electrically connected to the power management module.
Additionally, a
21 mains adapter 58 can be included, with an Universal AC mains converter to
an intrinsically safe 12
22 VDC output. The hardware configuration includes an auxiliary power output
60 that is current
CA 02404625 2002-10-18
1 limited, voltage limited, short circuit proof and ESD (electrostatic
discharge) protected.
2 The hardware further comprises microcomputer supervisory function circuits,
generally
3 represented by the numeral 62. The circuits 62 contain a real time clock
which is designed to
4 produce interrupts to initiate samples. The circuits 62 also include micro
central processing unit
clocks that have features of full speed, reduced speed and halt. The circuits
62 further have a
6 power supply monitor, watchdog timers, and system reset functions. The reset
functions include
7 resetting on power activation or power interruption, and resetting on
certain recoverable system
8 faults.
9 The microcomputer 64 includes memory storage means that contains the static
random
access memory 66, . non-volatile read-only memory 68, electrically erasable
read only memory 70,
11 and flash cache memory 72. The memory means will be electrically connected
to the
12 microprocessor 73 for interaction as is well understood in the art. The
SRAM 66 is commercially
13 available from NEC Co. under the name/parts number UPD431000AGZ; the ROM 68
is
14 commercially available from ATMEL Co. under the name AT29C020A; the EEPROM
70 is
commercially available from ATMEL under the name AT28C256; and, the Flash
memory 72 is
16 commercially available from AMD under the name AM29F032B. The
nucroprocessor 73 is
17 commercially available from INTEL Co. under the name SB80C188EC13.
18 A local RS-232C 72 serial port is incorporated into the design that allows
for terminal
19 connection detection, port configuration and instrument configuration via a
local terminal such as
a laptop computer 72a. A universal asychonrous receiver-transmitter (UART) 74
that has a port
21 configuration and means for hardware handshaking is electrically connected
to the RS-232C. The
22 UART is commercially available from EXAR Co. under the name XR15C850CM.
16
CA 02404625 2002-10-18
t An RS-485 serial port 76 is incorporated that has port settings, hardware
handshaking
2 means, and provisions for access to smart sensors and process devices. The
RS-485 port allows
3 electrical connection to smart devices such as the digital sensors
previously described. The RS-
4 485 port is also electrically connected to a UART 77 which in turn is
electrically connected to the
microprocessor 73.
6 Indicator and display means 78 are included which in the preferred
embodiment may be a
7 LCD. The LCD is suitable for graphics, digits, etc. to provide rudimentary
process data display,
8 setup guidance and error reporting. It is possible to use light emitting
diodes which emit green,
9 yellow, and red light for okay, warn, and fail indicators.
Manual input is possible via the manual input module 80 which can be push
buttons [under
11 cover] for master reset, simple set up, display configuration, etc. A
digital input capture port 82
12 is included that can monitor signals for state, change of state, timing and
counting applications
13 using an external contact sensor.
14 An analog sensor and readout module is generally represented by numeral 84.
The
configuration shown has three analog sensor ports arranged as shown, namely
86, 88, 90. The
16 integrated precision pressure port 86 will have one or two channels,
contain temperature
17 compensation means, conversion means for converting the signal to
engineering units, contain 4/6
18 wire resistive excitation, and have the ability to measure absolute or
differential pressures. An
19 optional remote or internal sensor port 88 is included that has one 4/6
wire excitation sensor, the
sensor being typically a moderately accurate process temperature or pressure
sensor. An optional
21 remote or external sensor port 90 may be included with one 6 wire
excitation sensor being
22 connected. The port 90 may be employed if the second internal port is not
used.
17
CA 02404625 2002-10-18
1 The senor ports 86, 88, 90 are electrically connected to the Analog
Excitation
2 Conditioning Circuit 91 a which in turn is electrically connected to the
analog multiplexer 91 b.
3 The signal may be directed directly to the microprocessor 73, or as in the
preferred embodiment,
4 is directed to the Precision Analog to Digital Converter 91c. The Analog
Multiplexer 91b is
commercially available from MAXIM Co. under the name MAX4052A. The Precision
ADC 91c
6 is commercially available from BURR BROWN Co. under the name ADS 1211 E. The
ADC 91 c
7 is electrically connected to the microprocessor 73 as shown in Fig. 3.
8 A minimum of one sensor of any type is needed for collection of data. As
noted above, a
9 maximum of three channels of analog sensors, two of which can be pressure
(P) or differential
pressure (dP) sensors may be included with this system. Thus, the integrated
analog sensors via
11 port 86 and 88 are a high accuracy, 6-wire measurements that allows the
following combinations:
12 P, dP, P+P, P+dP. The external analog sensor via port 88 or port 90 is of
moderate accuracy and
13 can be 4-wire, or 4-2OmA type that allows the fotlowing combinations:
pressure (P), differential
14 pressure (dP), resistive temperature detector (RTD), P+RTD, dP+RTD.
An external contact type of sensor, operatively associated with the digital
input capture
16 82, detects state, change of state, or timing. A remote digital sensor 91
connected via the RS-485
17 port 76 may also be employed, with this type of sensor being commercially
available from a wide
18 variety of vendors.
19 A compact wireless modem 91d is included. The modem 91d has a UART
compatible
input and can use CDPD data exchange. The modem 91d has a low power RF output.
In the
21 preferred embodiment, the modem 91d is commercially available from Sierra
Wireless, Inc. as
22 previously noted. An antenna 91 e is shown to transmit data.
18
CA 02404625 2002-10-18
I According to the teachings of the present invention, one of the possible
instrument
2 configurations includes a connection to a hardwired land line telephone
network. Additionally,
3 wireless forms of communications may be used that include circuit switched
cellular via a
4 telephone modem; a digital terrestrial cellular means that is packet based;
or, a digital satellite link
means that is also packet based. Another option for the transfer of the data
includes use of the
6 RS-232C port 72 to a hand held terminal device or laptop computer.
7 Referring now to Fig. 4, a schematic flow chart of a first systems
architecture of the
8 present invention will now be described. A pressure from any source
throughout the oil and gas
9 facility SO can be communicated to the Fl 2. In the preferred embodiment,
the pressure is
communicated from an oil and gas well ~j5 completed to a hydrocarbon
reservoir. The pressure
11 may be communicated to the FI 2 from down hole, from the well head, from
flow lines, from a
12 separator, from a pipeline, process equipment, etc.
13 In Fig. 4, the pressure from a well completed to a subterranean reservoir
has been
14 communicated to the sensor 4 of the SDS 2. An analog temperature sensor 8
has also been
included. The sensors 4, 8 will collect pressure and temperature data, for
instance, and will then
16 transmit that data to the operating system 12 for processing as previously
discussed. The
17 operating system will then transfer this data to the field communications
module 20 which will be
18 capable of transmitting the digital information as shown in Fig. 3 as
numeral 152
19 The field communications module 20 will transmit the digital data to a
database engine
1 4 which is commercially available from Oracle Inc. under the name Oracle 8i.
The database
21 engine 154 will have loaded thereon field communication software 155 to
communicate with the
22 communications module 20. The database engine 154 will consist of a data
manager software
19
CA 02404625 2002-10-18
1 156 that is operatively associated with the database 158. In the software
context, when it is
2 mentioned that it is "operatively associated with", the phrase simply means
that the two
3 components can electronically exchange data between each other. The data
base 158 will have a
4 table configuration that will enable the storage of the various data that
has been received. Also
included will be a user interface module 160 that consist of software that
will interface with the
6 server 62 so that the server 162 and database engine 154 can communicate.
7 The information system's architecture also includes the interface ,164
loaded on the server
8 162. This interface 164 may also be located at the third party's location,
or loaded onto multiple
9 user computers 166a; 166b, 166c. 166d. Also loaded onto the third party's
computer 166a-166d
will be the browser. Thus, at this third party location, the user may access
the data base 158.
11 The database engine 154 may be located at the operator's own site. This
allows foi
12 security of the data, and control by the operator. Alternatively, the
database engine may be
13 physically placed at a third site separate from the operator's site.
14 According to the teachings of the present invention, multiple FI units may
be placed at
multiple locations, with the individual FI unit having the field
communications module wirelessly
16 transmitting to the data base engine 154.
17 Thus, the database engine 154 will have numerous sensor information stored
thereon,
18 from multiple measurement points. Additionally, multiple users can access
the database 158 from
19 multiple locations.
Referring now to Fig. 5, a schematic flow chart of a second systems
architecture of the
21 present invention will now be described. Under this scenario, the pressure
from the well .168 will
22 be communicated to the sensor 4 and in turn to the FI 2, which will in turn
communicate to the
CA 02404625 2002-10-18
I field communication module 20 which in turn is transmitted wirelessly 152 to
the data base engine
2 154. The database engine 154 will have loaded thereon field communication
software 155, data
3 manager software 156. The data base 158 will have a table configuration that
will enable the
4 storage of the various digital data that has been received. Also included
will be a user interface
module 160 that consist of software that will interface with the web server
170. A server
6 interface 176 is also included, with the server interface 176 functioning to
communicate between
7 the data base engine 154 and a web server 170.
8 As noted in Fig. 5, there are at least two examples of systems arrangement
with this
9 embodiment. First, the server interface 176 may be connected to the Internet
178, which in turn
allows the clients 166a, 166b, 166c, 166d, etc. to be connected.
11 Second, with the teachings of the present invention, it is possible that
the field sensors 4, 6
12 be directly connected to individual clients, such as the client 166d, as
denoted by the link 184.
13 This link 184 may be a wireless Cunk, as previously discussed, or may be a
phone line, or other
14 conventional means. The operator may wish to have this extra link for
security reasons, or to
have a back-up system. Regardless of the reason, the architecture allows for
this type of
16 arrangement.
17 Fig. 5 also shows the arrangement for the exception reporting. Thus, the
data manager
18 software 156 would allow for the processing of alarm conditions i.e.
wherein pressure and/or
19 temperature data exceeds some predetermined level. Thus, there is written
into the software a
routine that will recognize this exception, and the software will
automatically report the exception
21 to the clients 166a, 166b, 166c, and/or 166d as predetermined.
22 Fig. 6 is a schematic diagram of one embodiment of the server arrangement.
Thus, a first
21
CA 02404625 2002-10-18
I computer 167a can be used that is electrically connected to a second
computer 167b. The
2 computer 167a can have the user interface, hypertext markup language and the
field
3 communication loaded thereon. The computer 167b will have the database
manager and data
4 base loaded thereon.
Fig. 7 is a flow chart of the digital signal processing of the present
invention. Thus, the
6 signal from the smart device 300 is received 302 at the RS-485 device 76
which in turn is
7 transmitted to the UART 304. The UART will condition the signal to be
accepted by the
8 microprocessor 306. Depending on the mode of operation of the operating
system, the
9 microprocessor 306 may then forward the reading to the UART 74 in the step
308 which in turn
is sent 310 to the RS-232C 72. The RS 232C 72 allows for a local dump to the
local terminal
11 computer 312 where a user can access the collected data on site, for
instance.
12 Alternatively, the mode of operation may dictate that the data be channeled
to the UART
13 314 which in turn will channel the signal to the wireless modem 91, as
shown in sequence step
14 316. The modem will transmit the signal to a remote computer as seen in
step 318. From the
remote computer, the data may be disseminated via various means such as
previously noted with
16 reference to Figs. 4 and 5.
17 Fig. 8 is a flow chart of the analog signal processing of the present
invention. Thus, the
18 signal from the analog sensor devices 86, 88, 90 are received at the analog
excitation conditioning
19 module and analog multiplexer 320 where the analog signal is conditioned
and forwarded to the
niicroprocessor in step 322. Depending on the mode of operation of the
operating system, the
21 microprocessor may then forward the reading to the UART 74 in the step 324
which in turn is
22 sent 326 to the RS-232C 72. The RS 232C 72 allows for a local dump to the
local terminal
22
CA 02404625 2002-10-18
1 computer 328 where a user can access the collected data on site, for
instance.
2 Alternatively, the mode of the operating system may dictate that the data be
channeled to
3 the UART 330 which in turn-will channel the signal to the wireless modem 91,
as shown in
4 sequence step 332. The modem will transmitt the signal to a remote computer
as seen in step
334. From the remote computer, the data may be disseminated via various means
such as
6 previously noted with reference to Figs.4 and 5.
7 Fig. 9 is a flow chart of the sequence of powering the sensors in order to
take readings as
8 well as the sequence of steps of taking a reading. Thus, the operating
system generates a wake up
9 signal 354, at a pre programmed time interval, which will cause the sensors
to be powered up
356. The sensors will take a reading, as denoted in block 358. The operating
system will then
11 cause the sensors to be powered off360.
12 Thereafter, the operating system will convert 362 the raw sensor values,
stored in the
13 cache memory, to real units utilizing a conversion algorithm as previously
stated. The converted
14 readings will then be displayed 364 on the LCD. -The converted data is
stored into the memory
366. The operating system will determine the next broadcast time point,
pursuant to a
16 predetermined time interval, and at the broadcast time, the field
instrument (via the
17 communications module) will send the data to a local computer and over the
modem 368. The
18 operating system will then calculate the next wake up time 370 and
thereafter generate a signal
19 which causes the sensors to power down 372(referred to as sleep). After the
expiration of the
predetermined time interval, a wake up signal is generated thus generating the
loop back to the
21 step seen in block 354, with the steps being repeated as shown in Fig. 9.
22 Referring now to Fig. 10, a schematic illustration of the enclosure 400 of
the present
23
CA 02404625 2002-10-18
1 invention will now be described. In the preferred embodiment, the enclosure
400 includes a
2 generally cylindrical base 402 that has an outer cylindrical surface 404
that in turn has extending
3 therefrom four projecting openings (only openings 406, 408, 409 are shown in
Fig. 7). The
4 openings are generally cylindrical in nature and will have an outer diameter
410 that extends to
the inner diameter 412. The inner diameter 412 will have connection means such
as an internal
6 thread means 414 that will sealingly engage with an adapter having mating
thread means. All four
7 openings will have similar internal thread means. 0-rings may be used to aid
in sealing. Other
8 connection means include use of pins as well as welding adapters in place.
As seen in Fig. 10, the
9 base contains a top 416 with an opening for placement of the LCD 418.
The Liquid Crystal Display (LCD) 418 is also shown, with the LCD being
electrically
11 connected to the printed circuit board. The LCD is electrically attached to
the digital pressure
12 readout as previously stated. Thus, the operator can view the digital
pressure readout utilizing
13 the enclosure 400. The LCD 418 is a custom layout available from Varitronix
Ltd.
14 Therefore, the enclosure 400 is a closed container once the adapters have
been placed
within the openings. This enclosure 400 represents an explosion proof closed
container. As will
16 be understood by those of ordinary skill in the art, hydrocarbons can be
hazardous andlor
17 corrosive materials. In accordance with the teachings of the present
invention, the pressure from
18 the wells will ultimately be communicated to the sensor within the
openings. An important aspect
19 to the invention is to withhold pressure from the inner chamber 229.
Additionally, the inner
chamber 420 will house the printed circuit boards for the sensor, memory,
operating systeni,
21 modem, battery, etc. Thus, the enclosure must also be capable of
withstanding an internal blast.
22 Remember, hydrocarbon fluids and gas are extremely flammable with low flash
points.
24
CA 02404625 2002-10-18
I Fig. 11, which is an operations and data flow chart, will now be described.
In particular,
2 Fig. 11 depicts the system software & firmware of the operations and data
flow. The operating
3 system contains a supervisor means 90 which technically contains the
hardware circuit 62 from
4 Fig. 3 . The supervisor means 90 also contains additional firmware that
includes a calibration map
loader means 92a for precision pressure maps, RTD (resistive temperature
detector) calibrations,
6 and special purpose calibrations for custom sensors on the external analog
input channel (i.e. 4-
7 20mA conversion). Also included is the real time clock means 94 that will be
continuously
8 powered. The real time clock 94 has a programmable delay to the next
microprocessor interrupt
9 for data sampling.
The supervisor 90 further contains the interrupts and scheduler 96 for data
sampling. The
11 firmware installer 98 contains a boot loader that can be accessed via the
local terminal or via the
12 remote communication channel. The command interpreter means 102 is included
and contains
13 means for providing the sensor configuration, power management
configuration, RTC
14 configuration, UART configuration, memory configuration, display
configuration and allows
access to raw sensor values, process values and various intermediate
calculation results.
16 The measurement data management module 204 is electrically connected to the
supervisor
17 means 90. The measurement data management module 204 includes means 206 for
generating
18 process statistics and higher level calculations done on process variable
calculation results. The
19 measurement data management module 204 will also contain means 208 for
trending, and means
210 for time compression. Some level of statistics and process data can be
kept for some period
21 of time including the lifetime of the device. In the preferred embodiment,
the oldest data'will get
22 compressed the most, while the most recent data is saved at higher
resolution (both time and
CA 02404625 2002-10-18
1 amplitude). Additionally, means 212 for archiving the data is provided.
2 The supervisor will be operatively connected to the system functions.module
214. The
3 system functions module 214 includes the power management means 216 that
allows for switched
4 modem power, switched analog circuit power, and in some cases switched
external power. Also
included will be system identification 218 that will digitally contain
information such as serial
6 number, production lot, hardware and firmware revision codes, model number,
build date and
7 factory, original configuration, current configuration, first day placed in
service and other similar
8 data.
9 Additionally, a device maintenance means 220 that includes maintenance logs,
with the
logs containing the last service date, operator and record locator number;
last calibration date,
11 calibration source, calibration ID and current calibration status;
enclosure access logs that detail
12 when the enclosure has been opened and detect that service was performed,
and detect if
13 tampering has occurred. The device management 220 will also update the
maintenance history
14 and run-time operating statistics.
The device management 220 has preventative maintenance indicators that include
count
16 down clocks, etc. to notify of upcoming preventative maintenance sessions.
Additionally, there
17 are checks for battery maintenance/replacement that may indicate when
battery charge is low, the
18 batteries are old, or won't recharge properly.
19 A watchdog timer means 222 has been included. The systems functions module
contains a
non-volatile memory control that will have a cache memory and EEPROM memory. A
system
21 errors and alarms means 224 is included that indicates if the error is
recoverable during a current
22 session, or recoverable on the master reset, or recoverable only with
physical intervention.
26
CA 02404625 2002-10-18
1 Another feature is that the system will have checks and diagnostics
activated on start-up, a system
2 for performing self-checks/diagnostics, and a monitor for the status of the
RTC (real time clock).
3 Means for monitoring internal analog points is included. These checks are
triggered on power up,
4 or manually, or through the local terminal connection, or remotely through
the wireless
connection. System warnings and error alarms are produced out of the
communications ports
6 when a diagnostic fails or receives a suspicious value. The system logs
these error/exceptions,
7 and a local error history record is kept in case of outgoing alarms are
missed.
8 Another module of the operations and data flow is the process monitoring
module 226.
9 The module 226 includes a sample sequence algorithm 228 which determines
when and how to
shift between various sample rates, trigger modes, calculations and data
analysis. Thus, the
11 process data sampWig options include scheduled sampling where process
values are determined at
12 a suitable rate on a fixed or sequenced schedule. Typically, this sampling
is used when the
13 process values vary slowly or not at all. Also available is adaptive
sampling wherein process
14 values are deterrnined at a dynamic rate determined by the recent history
of the process. The
adaptive sampling is typically used when process values vary erratically.
16 The process monitoring contains process variable calculation means 230 that
allows for
17 AGA 3 or AGA 8 and API "Standard" gas-fluid calculations that provide for
material
18 composition correction. The calculation means 230 includes various fluid
characteristics, tables,
19 and equations and may contain orifice meter device descriptions (materials,
dimensions, specific
ID's, etc). Among the process data calculation options are the ability to
obtain current values and
21 states for the process and system. Additionally, the history of values and
states for the process
22 and system can be obtained. This history can be used to determine process
statistics such as the
27
CA 02404625 2002-10-18
1 maximum, minimum, average, total, etc. of the parameters thus measured.
2 Also included in this module is the process alarm means 232 that is based on
captured,
3 converted and combined signals from both local and (if installed) remote
sensors. The process
4 alarm means 232 may use default or predefined process monitoring algorithms
and alarm
conditions or user defined algorithms and logic. This module will notify of an
alarm condition
6 through the display and will send a message out the RS-232 and wireless
ports.
7 The measurement trigger rates means 234 has single, multiple and/or auto-
repeating
8 sequences that may be combined in larger sequences using various process
dependent algorithms.
9 Means 234 contains adaptive and conditional sampling methods that include
process variable
triggered sequences and sampling rate changes. The triggers may be derived
from process
11 variables, proportional, rate, derivative, integral and state inputs. The
sampling methods include
12 remotely triggered sequences and sampling rates, and allow remote commands
to force branches
13 within sequence logic.
14 Another module is the data acquisition 236 that includes a sensor response
conversion
238. For the high precision pressure sensors, an iterative interpolation is
used across a pressure-
16 temperature map until convergence. -For other simple sensors, an
appropriate 1-D conversion
17 may be used to compensate the sensor's transfer function. A ADC readout and
control 240 is
18 provided that allows for ADC settings 242 and MLJX control 244, that is
connected to multiple
19 analog sensors, and ADC channel selection 246.
A communications and protocol manager module 248 is also included that allows
the
21 operator to select appropriate data representation and protocol for
conununication channels. An
22 RS-485 port 76 is included that may be connected to the external smart
sensors, or may be
28
CA 02404625 2002-10-18
I connected to other control systems, or may be connected to alarm functions,
or may be connected
2 to process monitoring. The RS-232C port 72 is included which allows for a
local terminal access
3 to the command interpreter 102. The RS-232C allows for local data retrieval,
optional periodic
4 quality control and calibration access, optional firmware update access,
sensor configuration,
S hardwired configuration, local diagnostics and debug access.
6 A wireless channel management means 254 is included that contains data
compression
7 means 256, error correction means 258, data encryption 260 and means for
authorization and
8 access control 262. Data encryption is commercially available from several
vendors and the data
9 encryption means may use the Data Encryption Standard (DES). Data encryption
means 260 is
commercially available from RSA Data Security Inc. under the standard RC-4 and
RC-2, and both
11 of these are covered under the standard CDPD 1.1, which the wireless modem
uses.
12 Compiled data may be extracted through the local terminal port by a service
technician.
13 The data can then be manually carried to data management facility. This
data dump mode is used
14 primarily as a back-up if the remote data dump mode is inoperative or
unreliable.
As noted earlier, in one of the preferred embodiments, the collected data is
communicated
16 through the wireless modem to a remote point. This communication may be
initiated either by the
17 instrument via the installed operating system or initiated by a remote user-
database server. The
18 data may be routed through a pubGc telephone network, or the Internet or a
private
19 communications network to one or more users or databases utilizing TCP/IP.
In yet another
mode, data is exchanged during an interactive session to provide "real time"
readout to either the
21 local terminal or a remote user.
22 In the alarm mode, process and system status information is sent
automatically through
29
CA 02404625 2002-10-18
l one or more of the instrument's communication channels. Data delivery is
initiated when a
2 process value calculation or system error determines that an alarm condition
exists. Typical
3 examples would be low flow, vver pressure, total volume, limits etc.
4
APPLICATIONS
6 An application of the novel instrument and system herein disclosed includes
flow metering.
7 The instrument samples data at a rate of up to once per second to enable
high temporal resolution
8 flow calculations to be performed. The system would be suitable for custody
transfer accounting,
9 point-of-use metering, and transmission pipeline leak checking. The
instrument normally acts in a
remote data dump mode to deliver logged flow data and flow statistics to a
user's database via a
11 wireless digital modem. If required, the instrument can switch into alarm
mode to signal that a
12 process variable or state is out of specification or it can be periodically
interrogated to read
13 process conditions. The location of the instrument would include the
wellhead or pipeline
14 monitoring station. Communication means include wireless communication
provided either by
terrestrial cellular service (digital packet or circuit switched) or digital
satellite link. The primary
16 requirements would be for remote, unattended and accurate collection and
time stamping of flow
17 rate and total volume data.
18 Another appGcation would be flow metering using orifice meters. The
instrument would
19 require an internal analog P sensor, an internal or external dP sensor (as
required by the accuracy
needs of the location) and an external RTD temperature sensor. Flow rate or
total volume
21 through an orifice meter determined using orifice characteristics and AGA
flow equations.
22 Yet another application would be with a turbine or displacement flow
meters. The
CA 02404625 2002-10-18
1 instrument requires an internal analog P, an external RTD temperature sensor
and one or more
2 digital input capture channels to count pulses from the flow meter. Accurate
flow rate
3 determination is achieved by using pressure and temperature compensation in
conjunction with
4 the digital input count rate.
Still yet another application includes an ultrasonic and multi phase flow
meters. The
6 instrument requires an internal analog P, an external RTD temperature sensor
and a digital
7 communication port (RS-485) to interface the ultrasonic flow meter. Accurate
flow rate
8 determination is achieved by using the pressure and temperature values to
determine the Reynolds
9 number of the flow profile past the flow meter, which in turn allows
accurate correction of the
flow meter readings.
11 With the teachings of the present invention, the instrument and method can
be used for
12 production monitoring and optimization. The instrument samples data about
once per minute to
13 monitor production pressure. Instrument acts in a remote data dump mode to
deliver logged
14 pressure data and statistics to a user's database. If required, the
instrument can automatically
switch into alarm mode to signal that a pressure is out of specification or it
can be periodically
16 interrogated to read the current pressure. The instrument would be located
on or near the
17 wellhead. Communication means includes wireless communication provided
either by terrestrial
18 cellular service (digital packet or circuit switched) or digital satellite
link. Primary requirements
19 include remote, unattended determination of wellhead pressure. Wellheads
would be equipped
with an instrument using both a P and RTD sensors. Pressure measurement rate
is on the order of
21 minutes to hours, typically time stamped, logged and dumped after many
days. Instrument
22 generates an alarm immediately if pressure deviates outside an established
performance band.
31
CA 02404625 2002-10-18
While preferred embodiments of the present invention have been described, it
is to be
2 understood that the embodiments described are illustrative only and that the
scope of the
3 invention is to be defined solely by the appended claims when accorded a
full range of
4 equivalence, many variations and modifications naturally occurring to those
skilled in the art from
a review thereof.
6
7
32
