Note: Descriptions are shown in the official language in which they were submitted.
CA 02595031 2007-08-09
G13:1068
APPARTUS AND METHOD FOR CONTENT DISCRIMINATION
Field of the Invention
Apparatus and method for content discrimination and more particularly for the
detection
and use of surface levels and transition levels of stratified liquids and/or
of the gradients in a
liquid.
Content discrimination providing volume and relative position of different
liquids in a
container or different gradients in a physical, chemical or electrical
property of a liquid is useful
in many industries.
It is particularly useful in the gas industry where liquids are recovered from
gas wells as a
byproduct to the gas. These liquids called natural gas liquids (NGLs), are
separated from the gas
stream at the well site and placed in storage tanks (condensate tanks). Some
of these same
liquids are transported within the gas stream and are condensate out of the
stream at compressor
stations. The heavier liquids, BS&W and water primarily, are transported to
water plants.
1
CA 02595031 2007-08-09
G13:1068
These liquids stratify in the storage tanks because of differences in specific
gravity or
density. Oil, being the lightest of the liquids, floats on top. There are
various classes of oil
related to the type and degree of contamination. The classes of oil from gas
wells are identified
and defined in a Bureau of Land Management (BLM) brochure entitled "Onshore
Oil and Gas
Operations; Federal and Indian Oil and Gas Leases; Onshore Oil and Gas Order
No. 4;
Measurement of Oil" issued under 43 CFR 3160 and published in the Federal
Register at
Volume 54, No. 36, February 24, 1989 and effective August 23, 1989. The upper
liquids in
order from the top are clean oil, dirty oil and waste oil. These liquids float
on water with bottom
sediment and water (BS&W) being at the bottom of the tank.
These liquids and the management of them by variable height inlet/outlet
orifices are
disclosed in PCT application Serial Number PCT/US2006/004479 filed February 8,
2006 and
U. S. Provisional Application No. (Docket No. G13:1080P) filed May 16, 2007,
both being assigned to the same Assignee.
Some apparatus and methods of determining volume and position of the various
NGLs
are disclosed in Provisional Patent Application Serial No. 60/810,013, filed
May 31, 2006.
Management of different liquids, and particularly the liquids from gas wells,
is disclosed
in the concurrently filed Provisional Patent Application having docket number
G 13:1070.
The invention disclosed and covered by the application is not limited to use
in these
particular liquids. However, for the purpose of understanding the concept and
some applications,
2
CA 02595031 2007-08-09
G13:1068
the invention will be disclosed in the context of liquids from natural gas
wells stored in
condensate tanks, such as the 20 foot high, 400-barrel or 500-barrel tanks
used in gas fields.
Typically there is air above the liquids, possibly saturated with gas vapors.
The content discrimination system of the invention provides the volume and
levels of
each stratified liquid. This information is available as numeric value, such
as 50 barrels and
between 12 and 14.48 feet high for a 400 barrel tank, or values that can be
converted to volume
and position or as a display indicating volume and position.
The information as to type of liquid is gathered by a capacitive sensor that
is moved
vertically through the various liquids. The capacitive sensor has capacitor
plates that are
surrounding liquids in the tank.
The capacitor plates may be rectangular in shape with facing parallel flat
surfaces spaced
a specific distance apart. Alternatively, the plates may be coaxial cylinders
a selected distance
apart or a single plate, with a nearby grounded body as the other plate.
The dielectric coefficient of air and each type of liquid results in a
different capacitance
as the air or liquid resides between the plates as the dielectric.
The capacitor plates may be electrically connected between an excitation
terminal and an
input terminal to digital converter. A particularly effective converter is the
AD7745-24 Bit, 1
Channel Capacitance to Digital Converter from Analog Devices (www.analog.com).
This
3
CA 02595031 2007-08-09
G13:1068
Converter has an internal temperature compensation of the output of the
circuit. An external
temperature sensor, such as an RTD, thermister or diode for monitoring the
temperature of each
liquid or a liquid in a container, may be coupled to the Converter.
Another circuitry that may be used as the dielectric to digital converter
consists of an
astable oscillator and the capacitor plates in and insulated from the liquid.
The capacitor plates
are part of a capacitive circuit that involves a resistor to set the frequency
of the oscillator. With
air between the plates, the resistor is adjusted so that the frequency of the
oscillator is 200
kilohertz. Thereafter, the frequency of the oscillator changes and represents
the dielectric
between the plates. The frequency can be calibrated with the different liquids
in the tank so that
the type of liquid is known from the frequency.
The operating frequency of the oscillator is converted to a digital signal by
a
microprocessor functioning as a signal processor. An external temperature
sensor for sensing the
temperature of the liquid between the plates also has an input to the
microprocessor to appear as
information at the output of the processor.
The capacitor plates of the oscillator for use in liquids from gas wells are 1
centimeter
wide and 8 centimeters long with spacing between the plates of 1 1/2
centimeters. The plates are
covered by a thin layer of plastic, such as PVC, or some other material that
will provide long
term use in the environment of use, such as the corrosive liquids from gas
wells. Also, the size
and location of the plates will vary with the electronic circuitry coupled to
the plates and the
environment of use.
4
CA 02595031 2007-08-09
G13:1068
The dielectric to digital converter consisting of either the AD 7745 converter
circuit, the
astable oscillator and signal processor or some other circuitry having a
digital signal output
representative of the dielectric coefficient and thereby identifying each type
of liquid in a tank.
This digital signal out is applied to a communications protocol converter for
use with any of the
standard protocols used in the industry of interest.
The vertical movement of the content discrimination sensor in the liquids in a
storage
tank is monitored to provide the position or elevation of the sensor in the
container and thus the
detected levels of the liquids in the container. In one form of the invention
the housing for the
sensor is moved up and down by an adjusting and measuring rod that passes
through a gear
mechanism. The adjusting and measuring rod has teeth or indentions such as
disclosed in the
above-referenced PCT Application and also in the provisional patent
application Serial Number
60/810,013 filed May 31, 2006. The gear mechanism is driven by hand or by a
motor. If driven
by hand, the operator notes both the distance and direction of travel of the
measuring rod and
thus knows the position of the sensor inside the tank. If the adjusting and
measuring rod is
driven by a motor, a sensor for distance and direction of travel is included
in the motor drive
mechanism. Alternatively, the housing is attached to a nut on a vertical lead
screw in the tank so
the carriage moves vertically in the tank when the lead screw is turned. The
nut and housing for
the sensor are held in place to prevent rotation of the sensor by a guide or
support pole that
extends vertically in the tank adjacent to and parallel to the lead screw. The
lead screw may also
be turned manually or by a motor inside or outside the container.
Additionally, instead of a
separate carriage and drive mechanism for the movable sensor, the sensor may
be carried on the
5
CA 02595031 2007-08-09
G13:1068
same carriage attached to a nut on a lead screw as that for the housing for
variable height
inlet/outlet orifice device as disclosed in the above-referenced PCT Patent
Application and as
disclosed in the above-referenced provisional patent application filed on May
31, 2006.
The contents in a container such as a condensate tank at a well site, a
compressor station,
water plant or an injection well may be provided to instruments at the site,
at the tank or at a
remote site. The content discrimination system information may be used for
inventory control,
scheduling of trucks to reduce truck traffic, managing the liquids in the tank
and/or managing a
gas well.
The content discrimination probe disclosed in this application may be used as
the volume
and level sensor in the systems disclosed in the above-referenced Provisional
Patent Application
Serial Number 60/810,013 filed May 31, 2006 and U.S. Patent Application Serial
Number
11/413,774 filed Apri128, 2006.
The invention advantageously combines components and methodology of electronic
automation with variable height inlet/outlet orifices and in-tank, variable-
height content
discrimination equipment to enable the accurate management of stratified
layers in a liquid
storage tank, or other similar type of tank in different industries, without
the operator physically
going to the top of the tank and adjusting the position of the inlet/outlet
orifice to the correct
height.
6
CA 02595031 2007-08-09
G13:1068
Additional features and advantages of the invention will be apparent from the
detailed
description which follows, taken in conjunction with the accompanying
drawings, which
together illustrate, by way of example, features of the invention; and
wherein:
7
CA 02595031 2007-08-09
G13:1068
Brief Descriution of the Drawings
Fig. 1 is a block diagram of a content discrimination sensor, according to
this
invention;
Fig. 2 is a functional block diagram of a dielectric to digital converter,
according to this
invention;
Fig. 3 is a block diagram of an alternative dielectric to digital (frequency)
converter,
according to this invention;
Fig. 4 is an illustrative diagram of movable content discrimination sensor in
a tank,
according to this invention;
Fig. 5 is a sectional view of the moveable sensor in Fig. 4, according to this
invention;
Fig. 6 is an elevation view of the moveable sensor of Fig. 4, according to
this invention;
Fig. 7 in a top plan view of the moveable sensor of Fig. 4, according to this
invention;
Fig. 8 is a photo of a test tank containing natural gas liquids and a content
discrimination
sensor, according to this invention; and
Fig. 9 is a graph of the output of the content discrimination sensor in the
test tank of Fig.
8, according to this invention;
Fig. 10 is an illustrative diagram of a content discrimination sensor with a
variable height
inlet/outlet orifice tool, according to this invention;
Fig. 11 is a block diagram of a liquid management system, according to this
invention;
Fig. 12 is a front-elevation view of a Bluetooth enabled, programmable PDA
useful with
the apparatus, in accordance with the present invention; and
Fig. 13 is a report available on a display or hard copy, in accordance with
the present
invention.
8
CA 02595031 2007-08-09
G13:1068
Detailed Description of the Invention
Reference will now be made to the exemplary embodiments illustrated in the
drawings,
and specific language will be used herein to describe the same. It will
nevertheless be understood
that no limitation of the scope of the invention is thereby intended.
Alterations and further
modifications of the inventive features illustrated herein, and additional
applications of the
principles of the inventions as illustrated herein, which would occur to one
skilled in the relevant
art and having possession of this disclosure, are to be considered within the
scope of the
invention.
Different physical, chemical and/or electrical characteristics of liquids in a
tank can be
sensed to determine the contents of the tank and when coupled with means for
determining the
position in the tank, the transitions from one liquid to another can also be
determined. The
different dielectric coefficients of liquids in a tank may be used to
discriminate and identify the
various liquids in a tank.
A capacitive probe is used to detect the coefficients of the liquids between
the capacitive
plates of the probe and creates an output signal indicative of the coefficient
and therefore the
type of liquid between the capacitor plates of the probe. The liquid or
dielectric is identified and
converted to a digital signal. A dielectric to digital converter creates a
digital signal output
which may be called the coefficient of the dielectric (liquid) in contact with
the capacitor plates.
Such a dielectric to digital converter 1 is shown in block form in Fig. 1. A
pair of capacitor
plates 3 and 4 is electrically connected to the dielectric to digital
converter 1. The digital signal
9
CA 02595031 2007-08-09
G13:1068
or converted coefficient that is the output of the converter 1 is applied as
an input to a
communication protocol converter 5 as shown in Fig. 1. Power is provided to
both converters by
a cable 6 that combines with the data output cable 7 from converter 5 as a
power and data cable
8. The two converters 1 and 5 may advantageously be housed in the housing for
the capacitance
probe with the power and data cable communicating with circuitry outside of
the tank in which
the capacitive probe is located. The dielectric to digital 1 may also have an
input from a
temperature sensor such as an RTD, thermistor or diode. In this way, the
temperature of the
liquid or dielectric between the capacitor plates 3 and 4 may also monitored.
Additionally, the
converter 1 may have an input from a pressure sensor 11 that is useful in
determining the volume
of the liquid above the capacitive plates 3 and 4 when there is only one type
of liquid above the
capacitive probe 1 in the tank. The pressure is monitored by a pressure sensor
11 and the
temperature is monitored by a temperature sensor 9.
A functional block diagram of a dielectric to digital converter is shown in
Fig. 2. The
particular capacitance to digital converter or dielectric to digital converter
shown in Fig. 2 is an
AD7745-24 bit, 1 channel Capacitance to Digital Converter available from
Analog Devices
(www.analog.com).
An alternative dielectric to digital (frequency) converter is shown in block
form in Fig. 3.
This dielectric to digital converter employs an astable oscillator 15 coupled
to parallel capacitor
plates 3 and 4. The frequency of the astable oscillator is initially set by a
variable resistor in a
frequency setting block 16. With air between the capacitor plates 3 and 4, the
frequency of the
oscillator 15 is set at 200 kilohertz. Thereafter, the frequency of the
oscillator 15 varies as the
CA 02595031 2007-08-09
G13:1068
dielectric or liquid between the capacitor plates 3 and 4. The variable
frequency, at the output of
the oscillator 15, is converted to a digital signal representative of the
coefficients of the various
liquids that pass between the capacitor plates 3 and 4 and applied to a
microprocessor 18,
functioning as a signal processor. The converted coefficient digital signal
from the output of the
microprocessor 18 is applied to a communications protocol converter 19 for
communication with
the selected communication network outside the tank containing the liquids
being measured. A
temperature sensor 13 is coupled to an input of the microprocessor 18 to
monitor the temperature
of the liquids that pass between the capacitor plates 3 and 4. Again, the
pressure of a single
liquid above the capacitive probe may be sensed by a pressure transducer 14
which provides an
output that may be used to determine the volume of the single liquid above the
pressure
transducer 14.
For use in natural gas liquids, the capacitor plates 3 and 4 are 1 centimeter
by 8
centimeters in width and length and have a spacing of 1 1/2 centimeters. The
size and spacing
will be dictated by the environment of use of the capacitive probe 1. Each
plate 3 and 4 is coated
with an insulating material such as a plastic that will stand up in a
corrosive and caustic
environment such as is found in liquids from gas wells.
Various components of the capacitive probe 10 shown in Figs. 1 and 3 may be
housed in
one housing or separately. For improved stability in operation and reduced
interference the
dielectric to digital converter 1 of Figs. 1 and 3 and communication protocol
converter 5 or
converter 19 are housed together. A housing 17 is shown in Figs. 4-7 as having
a rectangular
shape with flat rectangular capacitor plates 3 and 4 extending out to
interface with a dielectric
11
CA 02595031 2007-08-09
G13:1068
between the plates. The housing 17 is constructed of plastic, such as PVC, or
other material that
withstands the environment of use and includes a inner box for mounting the
electronic circuitry
of the probe 10.
The capacitive probe may be installed in new tanks (original installation) or
in tanks in
use (retrofit installation). The tank 20 diagrammatically shown in Fig 4
represents a 400-barrel
or 500-barrel tank that is commonly used to store liquids at gas well sites.
Tank 20 has two
outlets that are common in such tanks, the lower one 21 being a drain port and
a higher one 22
being the load-out port. Typically the drain port 21 is used to remove water
and other liquids to
bring the lower surface of the clean oil to a point just above the drain port
21. In this way, the
lower surface of the oil is below the load-out port 22 to satisfy a
requirement that is common in
the gas fields; that is, the lower surface of the clean oil must be 8" below
the center of the load-
out port 22. Alternatively, the controller 24 may be placed in a box that is
placed away from the
tank and may be mounted on a pole (not shown).
The capacitive probe 10 for content discrimination may be moved through the
liquids in a
number of different ways. Tanks that are located at well sites, compressor
stations and water
plants in gas production are typically of the 400 barrel or 500 barrel size
and stand 20 feet tall.
For this application, one advantageous way of moving the content
discrimination sensor
vertically in the tank through the liquids, is by use of a lead screw as shown
in Fig. 1. Linear
actuators above or inside the tank may be employed to move and position the
sensor.
12
CA 02595031 2007-08-09
G13:1068
The tank represented in Fig. 4 is a 20 foot tall 400 or 500-barrel tank that
is commonly
used in gas fields. The liquids in the tank in order of specific gravity from
the bottom is: bottom
sediment and water (BS&W) 26, water 27, waste oil or interface 28, dirty oil
29, clean oi130 and
air 31 which may also include some gas from the well. The use of the terms
waste oil, dirty oil
and clean oil in this representative use of the content discrimination sensor
are consistent with
the definitions set forth in the Onshore Oil and Gas Order No. 4 Measurement
of Oil brochure
issued by the Bureau of Land Management.
The housing 17 of the probe 10 is attached to a platform or carriage 32 by
some means
such as a strap 38. The carriage includes a cylindrical hole 33 that is
internally threaded to mate
with a lead screw 34. In this way the carrier 32 acts as a nut on the lead
screw to move the probe
vertically as the lead screw 34 is turned. A square pole 35 extends from the
top to the bottom of
the tank 20 to guide the carrier 32. The internally threaded hole, which
functions as the nut on
the lead screw 34, may be a separate piece such as a bushing 37 that is
inserted in the carrier 32.
In this way, the bushing may be made of a different material than the carrier
32. In any event,
the material that engages the lead screw 34 should have a surface and
consistency that permits
easy movement on the lead screw 34. The bushing 37 may advantageously be made
of carbon
filled PTFE which has a surface that moves easily on the lead screw 34 and
provides grounding
to avoid static electricity. The support pole 35 is attached at the bottom
through a plate 39 and
extension 40. Extension 40 has a square opening that corresponds to the square
shape of the pole
35 and includes a means for holding the support pole 35 in the plate 39. A
drive mechanism 42
on top of the tank 20 is coupled to the lead screw 34 to turn the lead screw
at a desired rate. The
drive mechanism 42 includes an electric motor 43 and an adaptor 44 in the top
of the tank 20 for
13
CA 02595031 2007-08-09
G13:1068
mounting the drive mechanism 42 and lead screw 34 and support pole 35. The
adaptor 44 is
threaded at the bottom to receive a support plate 45 that is threaded into the
bottom of the
adaptor 44 to locate and support the support pole 35. The lead screw 34 is
mounted in a pair of
thrust bearings 47 and 48 held in place in the adaptor 44 by a shelf at the
bottom of adaptor 44
and a nut 49 threaded into the top of the adaptor 44.
A photograph of a test tank with natural gas liquids is shown in Fig. 8. The
photo of Fig.
8 shows liquids from gas wells in a test tank where the liquids have settled
over a 48 hour period
of time. The liquids have stratified with clean oil 30 on top, dirty oi129
below the clean oil 30,
waste oil or interface 28 below the dirty oil 29 and water 27 below the other
liquids.
Fig. 9 is a graph of the output signals from the microprocessor 18 of Fig. 3.
The X axis
or horizontal axis of the graph is in inches from the top of the test tank
(Fig. 8) and corresponds
with the tape measure that is shown in the photo of Fig. 8. It is seen that
there is a change in
dielectric coefficient between 6 and 7 inches on the graph of Fig. 9 where the
sensor has moved
from air on the left to clean oil; the clean oil having a valve of
approximately 200 on the graph of
Fig. 9. The next change in coefficient shown on the graph of Fig. 9 is at 17
inches where it is
seen from Fig. 8 that the sensor was still in oil. However, this oil area is
different from the clean
oil 30 above and has been labeled dirty oil 29 because it contains
contaminates, such as bacteria,
which has changed the coefficient. There is another change at about 18 inches
and extends to 20
inches when the sensor passed through the waste oil or interface 28 and
entered into the water
27. The water 27 has a valve as shown on the graph of Fig. 9 of approximately
630 to 640. It
14
CA 02595031 2007-08-09
G13:1068
should be noted that the graph of Fig. 9 is the result of smoothing or
averaging the output of the
oscillator 15 in microprocessor 18.
Variable height inlet/outlet orifices have been found to be very useful in
storage tanks in
gas fields. A number of these variable height inlet/outlet orifices and ways
of controlling the
position of the orifice are disclosed in the above-referenced PCT Application.
One type of
variable height inlet/outlet orifice mechanism is shown in Fig. 10. An opening
or orifice 51 in an
elbow 52 is provided to receive a selected liquid inside a tank 50. The elbow
52 is attached to a
carrier 53 that is moved vertically in the tank by a lead screw 54. The
carrier 53 slides on and is
guided by a support pole 55 that extends from the top to the bottom of the
tank 50. The carrier
53 has a bushing 58 that is internally threaded and mates with the threads of
the lead screw 54.
Thus, when the lead screw 54 turns, the carrier 53 moves vertically to
position the orifice 51 at a
selected position in the tank 50. A capacitive probe 60 is attached to an
extension 59 of the
carrier 53 so that the capacitive probe may be moved vertically inside the
tank 50 whenever the
lead screw 54 is turned or rotated. A drive mechanism outside and on top of
the tank 50 turns
the lead screw 54 to move the carrier 53 vertically inside the tank 50. The
drive mechanism 61,
though the lead screw 54 and carrier 53, determine the position of both the
sensor 60 and the
orifice 51. To survey the contents of the tank 50 and provide a picture of the
contents, the carrier
53 is moved from the top of the tank 50 to the bottom of the tank while
sensing the dielectric
constant of the liquids in the tank. A magnet 63 is attached to and extends
above the carrier 53
and is sensed by and triggers a switch 64 attached to the mounting plate or
support plate 45 at the
top of the tank 50. The sensing of the magnet 63 by the sensor and switch 64
initiates the
operation of the capacitive sensor 60 and provides a reference for the
position of the sensor. As
CA 02595031 2007-08-09
G13:1068
the lead screw 54 turns and moves the sensor 60 through the liquids, the
position of the sensor 64
is referenced to the top of the tank through the switch 64 and magnet 63.
The operation of the capacitive sensor 60 and the moveable orifice 51
controlled by the
motor 61 in a system is shown in block form in Fig. 11. The output of the
sensor 60 is sent by
way of mod bus or some other protocol or some other way of communication to a
controller 70.
The controller 70 sends the information gathered by the sensor 60 to a
communication module or
remote terminal unit 71. The remote terminal unit may gather information at
the storage tank
site such as the weather by an sensor W 72 coupled to the RTU 71. The power to
the RTU and
the system at the storage tank may be provided by a solar panel 73 and solar
array and control 74
coupled to the RTU 71. The RTU 71 controls mechanical devices such as valves
75. The
operation of the system may be limited to authorized people only by use of a
human machine
interface device 76 which requires proper identification and password to
operate the system.
A network with one representative system on site for sensing, control and
communication
is shown in Fig. 11. The on-site system is used with a storage tank, such as
those found at well
sites, compressor stations, water plants and injection wells associated with
gas fields.
A content discrimination sensor 100 surveys the content of the tank (not
shown) and
provides the data to a controller 101. The controller 101 may be accessed
through a human
machine interface 102, such as a PDA (Fig. 12), at the tank site.
16
CA 02595031 2007-08-09
G13:1068
The controller 101 controls the mount of the content discrimination sensor 100
through a
motor control 104. Motor control 104 may control a separate motor for
positioning a variable
height inlet/outlet orifice in the tank or the same motor may move both with
the content
discrimination sensor mounted with an inlet/outlet orifice.
The controller also controls the operation of a horn 105 and a camera 106,
which may be
provided at the tank site.
The system at the tank site may be controlled from a remote control station
with a remote
terminal unit (RTU) 110 at the tank site. The on-site management may also be
accomplished
through the RTU 110 with a human machine interface 111.
A diagram of the front of a programmable, Bluetooth-enabled PDA is shown in
Fig. 12.
Such a PDA is available from MIG, Palm, HP, and literally dozens of other
manufactures and
may be used by operators at well sites to interact with the content
discrimination sensor system
and motorized drive for the variable height inlet/outlet orifice. Bluetooth is
a developing, world
wide, open, short-range radio specification that defines communication
protocols between
devices and computers. In other words, the content discrimination sensor may
be
Bluetooth-enabled to communicate with Bluetooth enabled PDAs. A programmable
PDA allows
custom application software to be run on the PDA, completing the link between
the PDA, the
content discrimination sensor, and an optional drive motor to adjust the
position of a variable
height inlet/outlet orifice.
17
CA 02595031 2007-08-09
G13:1068
Application software for the PDA may have the following characteristics:
= Image rendering based on digital data from the capacitive console.
= Interface controls that allow the operator to designate a stratified layer
within a tank.
= A Send control that allows the operator to tell the motor to position the
inlet/outlet orifice
at a certain layer.
= For tanks having a ground-level crank, rather than a motor, application
software may
notify the operator when the orifice has reached the desired location.
= Application software may include database capability, automatically logging
the
operator's identify, the tank being accessed, the time and date, and the
specific gravity
and quantity of liquid removed. The data may also include the temperature of
the liquid
and/or the specific gravity. This information may be used for custody transfer
and /or
inventory control.
A radio transmitter/receiver operating in the 900MHz range, which is available
from
MaxStream of Lindon, Utah, may be used to transmit content discrimination data
to a central
location, such as server 120 of Fig. 11. In some instances, a 900MHz device
may be sufficient. In
other instances, however, a repeater, or cellular modem, may be necessary to
transmit/receive
data.
A graphical interface for a desktop software application that could be used to
proactively
manage hundreds, or even thousands, of storage tanks throughout a local oil
field or a
world-wide oilfield is shown in Fig. 13. The software, via wireless radio
transmitter technology
or a cellular modem, may be set to poll each tank on a regular basis-for
example, once per
hour-depending on the frequency desired by an operator. Based on the polling
data received
18
CA 02595031 2007-08-09
G13:1068
from each tank, the software may provide a variety of reports not now
available to oil and gas
companies. Further, the software may provide management assistance in planning
daily, weekly,
and monthly trucking schedules, thus eliminating significant unnecessary
trucking charges that
arise from pumpers dispatching trucks for less-than-a-load quantities. The
software application
may be set to upload critical tank data on a periodic basis to an Internet
ISP/Storage facility, such
as Center7, of Lindon, Utah. Such entities offer multiple layers of redundant
security and data
protection to customers that need high-volume data storage/archiving.
Salient features of the desktop soflware application are as follows:
= Pre-set periodic polling or real-time access.
= On-demand polling for specific tanks or lists of tanks.
= Graphical representation of each tank, showing stratified layers, fill rate,
percentage of
hydrocarbons to water and other materials, as well as other relevant data
specified by the
operator.
= Historical charts for specific wells showing the well performance over the
course of time.
= Methodology cost analysis. For example, the software may calculate the
profitability of
current methodology at a particular well site in relation to optional
methodology. For
example, at well sites utilizing three-phase heater/treaters, which are
expensive to buy
and to fuel on a monthly basis, the software may calculate the projected
savings and ROI
of converting to a variable height inlet/outlet orifice approach.
= A daily tasks list, which automatically calculates, based on current volume
and fill rates
for all tanks, which tanks need which types of liquids drawn off and at what
time.
= A trucking planner; which would automatically coordinate trucking to a
particular part of
an oil field for the purpose of eliminating less-than-a-load dispatches. For
example, the
19
CA 02595031 2007-08-09
G13:1068
software, based on recent polling data, determines that tanks at three well
sites each have
30 barrels of water that need to be removed. The software, therefore,
recommends that a
single 100-barrel water truck be dispatched to the region to draw off 30
barrels from each
tank. This feature may be used on a daily basis or to forecast trucking
requirements
weeks and months into the future.
= An oil-sales planner, which automatically coordinates possible oil sales on
any given day.
For example, based on recent polling data regarding current volumes of light
oil in tanks
as well as fill rates for those tanks, the software determines that six tanks
in a particular
geographic region contain a total of 100 barrels of light oil. Assuming these
tanks utilize
variable height orifices, an oil transport may be dispatched to a region to
draw off the
light oil from the six tanks.
= Data reports with multiple sort keys. For example, an operator may want to
generate a list
of wells producing the highest ratio of hydrocarbons to water in descending
order.
By way of example, and without limitation, the invention may be described as a
system
for managing stratified liquids in a container, such as a storage tank,
comprising a variable
height, in-tank content discrimination sensor configured to identify liquid
layers of differing
dielectric coefficient and to indicate an elevation of the liquid layers, and
a motorized drive unit
for adjusting the orifice of a liquid management tool to intercept a selected
layer.
An external power source and a hand-held computer with a visual read-out that
receives
feedback from the in-tank content discrimination sensor via a wireless
connection may transmit
coordinates to the motor drive unit regarding orifice positioning. The hand-
held computer
CA 02595031 2007-08-09
G13:1068
automatically turns the motor off when the orifice has reached the optimal
position, or
alternately, notifies the operator that the orifice is in the optimal
position. The hand-held
computer includes on-board memory for storing tank management data, for
example, which
operator removed-or added-liquid from or to a stratified layer, the date and
time of the
operation and the volume of the liquid transported. The hand-held computer
functionality may be
replaced by other types of computers at remote locations which communicate
with the in-tank
sensor via various long-distance vehicles, such as radio frequency or
microwave.
It is to be understood that the above-referenced arrangements are only
illustrative of the
application of the principles of the present invention in one or more
particular applications.
Numerous modifications and alternative arrangements in form, usage and details
of
implementation can be devised without the exercise of inventive faculty, and
without departing
from the principles, concepts, and scope of the invention as disclosed herein.
Accordingly, it is
not intended that the invention be limited, but rather the scope of the
invention is to be
determined as claimed.
21
