Language selection


Patent 2205670 Summary

Third-party information liability

Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.

Claims and Abstract availability

Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:

  • At the time the application is open to public inspection;
  • At the time of issue of the patent (grant).
(12) Patent: (11) CA 2205670
Status: Expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • C10L 3/06 (2006.01)
  • F15D 1/02 (2006.01)
  • F17D 1/02 (2006.01)
(72) Inventors :
  • MORRIS, IAN (Canada)
  • PERRY, GLEN (Canada)
(73) Owners :
(71) Applicants :
  • 665976 ALBERTA LTD. (Canada)
(74) Associate agent:
(45) Issued: 1999-11-16
(22) Filed Date: 1997-05-16
(41) Open to Public Inspection: 1998-05-18
Examination requested: 1998-04-14
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data:
Application No. Country/Territory Date
PCT/CA96/00749 World Intellectual Property Organization (WIPO) (Intl. Bureau of) 1996-11-18


English Abstract

At pressures over 1000 psia, it is advantageous to add to natural gas an additive which is a C2 C3 and C4 hydrocarbon compound, CO, NH3 or HF or a mixture of such additives. Above a lower limit (which varies with the additive being added and the pressure), this results in a smaller Z factor, or (M w.Z) product, representing increased packing of molecules, and therefore leading to a decrease in the amount of power needed to pump the mixture or to compress it.

French Abstract

À des pressions supérieures à 1000 lb/po2, il est avantageux d'ajouter au gaz naturel un additif qui est un hydrocarbure composé C2 C3 et C4, CO, NH3 ou HF ou un mélange de ces additifs. Au-delà d'une limite inférieure (qui varie avec l'additif ajouté et la pression), cela se traduit par un plus petit facteur Z, ou un produit (M w.Z), qui représente un entassement accru des molécules, et conduisant donc à une diminution de la quantité de puissance nécessaire pour pomper le mélange ou le compresser.


Note: Claims are shown in the official language in which they were submitted.

1. A method of transporting natural gas by pipeline, which comprises:
(a) adding to such natural gas sufficient of at least one C2 or C3
hydrocarbon or a mixture of C2 and C3 hydrocarbons such so the
hydrocarbon, together with the C2 and C3 hydrocarbon (if any) originally
in the natural gas, forms a resulting mixture with a total C2 or C3
hydrocarbon content which is sufficient, at the pressure and
temperature to be used for transporting, to reduce the product of the z
factor and the average molecular weight of the resulting mixture to a
level lower than the product of the z factor and the average molecular
weight of the untreated natural gas, and
(b) transporting such resulting mixture by pipeline at a temperature
of between -40° and +120° Fahrenheit and pressure greater than
psia, said pressure and temperature being chosen so the resulting
mixture has no coherent liquid phase at the temperature and
pressure of transmission.
2. A method as claimed in claim 1, where the hydrocarbon is selected
(a) between 26 and 40% of at least one C2 compound if the
pressure is about 1000 psia, declining smoothly to about 6% to 15% of
said C2 compound if the pressure is about 2200 psia, or

(b) between 12% and 5% of a C3 compound, if the pressure is
about 1000 psia, declining smoothly to the C3 amount which will not
cause liquefaction at the pressure used when the pressure is above
1000 psia.
3. A method as claimed in either claim 1 or claim 2, in which there is not
more than 1% by volume of carbon dioxide in the resulting mixture.
4. A method as claimed in claim 1 or claim 2, in which there is not more
than 2% nitrogen in the resulting mixture.
5. A method as clamed in any of claims 1-4, in which the temperature at
which the resulting mixture is transmitted is between -20°F and
6. A method as claimed in any of claims 1-4, in which the pressure at
which the resulting mixture is transmitted is between 2160 psia and
1150 psia.
7. A method as claimed in any of claims 1-6 in which the C2 hydrocarbon
added to the natural gas is ethane.
8. A method as claimed in any of claims 1-7, in which the C3
hydrocarbon added to the natural gas is propane.
9. A gas mixture, for use in a pipeline at a pressure greater than 1,000
psia and a temperature of from -40 degrees F to +120 degrees F,
which comprises:
(a) from 68 to 92% by volume of methane;
(b) from 6 to 35% by volume of ethane;
(c) from 0 to 9% by volume of propane;

(d) from 0% by volume of C4 hydrocarbons to a percentage of C4
hydrocarbons which does not liquify at the pressure used;
(e) not more than 1 % of carbon dioxide;
(f) not more than 2% of nitrogen, the total being 100%, and such
mixture being completely gaseous with no liquid phase at the
temperature and pressure of intended operation.
10. A gas mixture as claimed in claim 9, said gas mixture being at a
pressure of 1000-2200 psia and a temperature of from -20 degrees F
to +120 degrees F.


Note: Descriptions are shown in the official language in which they were submitted.

CA 02205670 1997-OS-16
Field of the Invention
This invention relates to the transfer by pipeline of mixtures which contain
methane or natural gas.
Backgiround of the Invention
As is well known, methane is the largest component of natural gas, and
a sually accounts for at least 95% by volume of what is known as "transmission
specification" natural gas. Other usual components are ethane (usually about
propane (usually about 0.5%), butanes, pentanes and possibly hexanes
amounting to less than about 0.3%), with the balance being nitrogen and carbon
dioxide. In this disclosure, transmission specification natural gas will be
called "natural gas". For example, the natural gas as transmitted through the
of TransCanada Pipeline Limited from Alberta, Canada to Ontario, Canada has
the following percentage composition by volume:
Component Feed

Nitrogen 0.01270

Carbon Dioxide 0.00550

Methane 0.95400

Ethane 0.01970

Propane 0.00510

i-Butane 0.00170

n-Butane 0.00080

i-Pentane 0.00020

n-Pentane 0.00010

n-Hexane 0.00020

The relation between pressure, volume and temperature of a gas can be
expressed by the Ideal Gas Law, which is stated as PV = nRT, where:
P = pressure of gas
V = volume of gas
n = number of moles of the gas

CA 02205670 1997-OS-16
R = the universal gas constant (which, as is known, varies somewhat depending
on volume and temperature)
T = temperature of the gas.
If the equation is expressed in English units, the pressure is in pounds per
square inch
absolute (psia), the volume is in cubic feet, and temperature is in degrees R
Fahrenheit plus 460).
The Ideal Gas Equation does not give exactly correct results in actual
practice, because gases are compressible. Gas molecules, when compressed, pack
more tightly together than would be predicted by the Ideal Gas Equation,
because of
intermolecular forces and molecular shape. To correct for this, an added term,
compressibility factor z, can be added to the Ideal Gas Equation. This is a
dimensionless factor which reflects the compressibility of the particular gas
measured, at the particular temperature and pressure conditions.
At atmospheric pressure or gage pressures of a few hundred pounds, the
compressibility factor is sufficiently close to 1.0 so that it can be ignored
for most gases,
and so that the Ideal Gas Law can be used without the added term z. However,
pressures of more than a few hundred pounds exist, the z term can be different
from 1.0 so that it must be included in order for the Ideal Gas Equation to
give correct
According to the van der Waals theorem, the deviation of a natural gas
from the Ideal Gas Law depends on how far the gas is from its critical
temperature and
critical pressure. Thus, the terms TR and PR (known as reduced temperature and
reduced pressure respectively) have been defined, where
TR = T
PR = P
T = the temperature of the gas in degrees R
T~ = the critical temperature of the gas in degrees R

CA 02205670 1997-OS-16
- -3-
P = the pressure of the gas in psia
P° = the critical pressure of the gas in Asia
Critical pressures and critical temperatures for pure gases have been
calculated, and are available in most handbooks. Where a mixture of gases of
composition is available, a pseudo critical temperature and pseudo critical
which apply to the mixture can be obtained by using the averages of the
temperatures and critical pressures of the pure gases in the mixture, weighted
according the percentage of each pure gas present.
Once a pseudo reduced temperature and pseudo reduced pressure are
known, the compressibility factor z can be found by use of standard charts.
One of
these is "Compressibility Factors for Natural Gases" by M.D. Standing and D.L.
published in the Engiineering Data Book, Gas Processors Suppliers Association,
edition (Tulsa, Oklahoma, U.S.A.) 1987.
When the compressibility factor z of methane is read from the charts, it
is found that the factor z is always less than 1.0 in normal temperature
ranges (i.e.
between about -40°F and 120°F) and that it decreases as 'the
pressure rises or the
temperature falls. Therefore, less energy need be used to pump a given volume
methane (measured at standard volume) at any given normal temperature than
be expected at that temperature if the methane were an ideal gas. This effect
is more
marked at higher pressures. Similarly, as the pressure is increased at a
temperature, more methane (measured at standard volume) can be stored in a
vclume than would be predicted from the Ideal Gas Equation. "Standard volume"
volume measured at standard pressure and temperature (STP)).
Natural gas, like methane, shows z factor changes with pressure. Under
about 1000 psia the dominant variable in the power relationship is the
molecular weight
of the gas. At this pressure level, addition of further amounts of ethane or
increases the molecular weight of the gas more rapidly than the z factor
Thus, there is an advantage to removing ethane and propane from the gas.
It is usual in the gas transportation and storage industry to try to strip out
higher hydrocarbons such as ethane, propane, butane and unsaturated

CA 02205670 1997-OS-16
from natural gas if the gas is to be transmitted through pipelines. This
leaves mostly
methane (with some traces of nitrogen and carbon dioxide) to be transported by
the gas
pipeline. The materials which are stripped out are then transported or stored
separately, often as liquids.
Summar)i of the Invention
It has now been found that, at pressures over 1,000 psia, it is
advantageous to add to natural gas an additive which is a C2 or C3 hydrocarbon
compound or a mixture of such additives. Above a lower limit (which varies
with the
additive being added and the pressure), this results in a smaller product of
the z factor
times the average molecular weight of the gas (hereinafter called the zMW
product ) than
would exist with methane alone, therefore leading to a decrease in the amount
power needed to pump the mixture or to compress it.
Detailed Description of the Invention
If ethane is the additive, enough ethane must be added to methane or
natural gas to give a gas composition having a minimum of about 26% ethane for
- operation at 1,000 psia and normal temperatures (-40°F to
+110°F). (All percentages
in this document are percentages by volume). Ethane can be added until just
the mixture separates into separate gas and liquid (which occurs at about 40%
for a pressure 1,000 psia and a temperature of about 35°F). To reduce
the danger of
liquefaction if there is inadvertent pressure drop, and to reduce temperature
generally operation at 25-35% ethane and 35°F to +40°F is
When the pressure is raised to 2,200 psia, the addition of enough ethane
to natural gas to give a gas composition having more than 6% ethane gives some
beneficial results. Thus, as pressure increases, in the range from 1,000 psia
to about
2,:?00 psia the beneficial results occur with less and less ethane. For the
beneficial results, however, an addition of enough ethane to give at least 15%
is preferred at pressures of 2,200 psia.

CA 02205670 1999-03-04
Thus, for ethane as an additive, an amount is added to give a gas which
has at least 26% ethane (but preferably 35% ethane) at 1,000 psia, and at
least 6%
ethane (but preferably 15% ethane) at 2,200 psia, with the minimum percentage
ethane decreasing smoothly with rise in pressure. Ethylene may be substituted
for all
or part of the ethane on a 1:1 volume basis. Where pressure fluctuates, as in
a gas
pipeline where the gas is compressed at compressor stations and becomes less
compressed as it flows between compressor stations, the pressure indicated is
maximum pressure to which the gas is compressed. In such a compression-
arrangement, it is preferred that the ratio between the most compressed and
the most
rarefied pressures of the gas not exceed 1.3:1.
C3 hydrocarbons alone can also be used as the additive. Minimum
useable percentage of the total gas mixture vary from a minimum of 5% at 1,000
to about 3% at 2,200 psia. Maximum amounts are those which will not cause
separation of a liquid phase at the temperature used. The C3 hydrocarbons may
be any
of propane, isopropane or propylene, separately or in admixture.
One or more C~ hydrocarbons may also be substituted, preferably on a
1:3.5 volume basis, for CZ hydrocarbons, but not to a point where they cause
of a liquid phase at the pressure and temperature of operation. (A 1:3.5 basis
that each standard volume of C3 hydrocarbon replaces three and a half standard
volumes of C2 hydrocarbon.) Generally, the limitation that a liquid phase
should not be
formed means that not more than about 12% of C3 hydrocarbons should be present
1000 psia and 60°F, and lesser amounts should be used as the pressure
increases or
temperature decreases.
Two or more of the C2 or C3 additives can also be used. The use of two
or more additives has a synergistic effect in many cases, so that less than
the minimum
amount of each is needed than would be needed if only one were present, in
order to
produce a zMW product smaller than that of an equivalent standard volume of
gas at the pressure and temperature involved.
At pressures over 1000 psig, CQ hydrocarbons do not contribute much to
the improvement of the zMW product. Thus C4 hydrocarbons are not additives

CA 02205670 1997-OS-16
contemplated by this invention. However C4 hydrocarbons which are already
in the natural gas need not be removed if they are present in insufficient
quantity to
liquify or to affect the zMW product very adversely. The presence of more than
1 % C4
hydrocarbon in the mixture is not preferred, however, as C4 hydrocarbons tend
to liquify
easily at pressures between 1,000 psia and 2,200 psia, and more than 1% C4
hydrocarbons give rise to increased danger that a liquid phase will separate
out. C4
hydrocarbons also have an unfavourable effect on the mixture's z factor at
just under 900 psia, so care should be taken that, during transport through a
that mixtures according to the invention which contain C4 hydrocarbons are not
to decompress to less than 900 psia, and preferably not to less than 1,000
The addition of amounts of additive below the lower limit (unless two
additives with a synergistic effect are used) actually increase the zMW
product over that
of methane or natural gas alone, and is thus detrimental. For example, when
pressure is 1,000 psia and the temperature is 35°F, mixtures of methane
and ethane
having less than about 26% ethane have a z factor greater than methane alone
percentages are based on volumes at standard pressures and temperatures).
ethane to increase the percentage of ethane from 2% to, for example 12% at
pressure and temperature is therefore counterproductive, as it increases the
product and therefore increases the energy required to pump or compress for
a given standard volume of gas. However, when more than 26% of ethane is
the z factor falls so much that the zMW product fiends to lower values than
that of pure
methane. The z factor continues to get smaller with increased percentages of
bringing with it a lower zMW product to the point where further increase of
ethane causes
separation of a liquid phase (at about 40% ethane at 1,000 psia and
35°F). Thus,
adding ethane to natural gas so that there is a mixture containing more than
ethane at 1,000 psia and 35°F leads to increased packing of molecules
and a
decreased zMW product, hence decreased pumping costs and more ability to store
wii:hin a given volume. At 1,350 psia and 85°F, improved results over
methane alone
are obtained when only 17% of ethane is present in the mixture. Where the
is increased to 1,675 psia at 35°F, mixtures with 13% or more ethane,
and the balance

CA 02205670 1997-OS-16
methane give improved results over methane alone. At 2,140 psia and
35°F, the
improved effect is shown in mixtures of 6% ethane and the balance methane.
By the avoidance of liquid phase in this disclosure is meant the avoidance
of enough liquid to provide a coherent liquid phase in the pipeline at the
and pressures used. Such a phase can create pipeline problems through pooling
in low
portions of the pipeline or forming liquid slugs which affect pumping
efficiency. A few
liquid droplets in the line however, can be tolerated.
The use of a hydrocarbon as additive has the additional advantage that
it permits transport of a mixture of methane or natural gas and the
hydrocarbon additive
in a single pipeline with less energy expenditure than if the two were
sE~parately in separate pipelines.
Brief Description of the Drawings
The invention will be described further in association with the following
drawings in which:
Figures 1A to 1 E are plots of capacity gain in percent against the content
of C2 hydrocarbons in a mixture of methane and ethane. Each of the plots shows
results at a different pressure. Figure 1 F shows calculations of flow ratios
for various
mixtures of methane and ethane..
Figures 2A and 2B are plots of capacity gain versus temperature (in
degrees Fahrenheit) for pipelines at 800 psia and 1,675 psia respectively.
Figure 3 is a summary of pipeline horsepower requirements for various
gays mixes, using a 36" pipeline operating at a maximum operation pressure of
psia, an inlet temperature of 80°F and a ground temperature of
Figure 4 is a plot of the horsepower requirements per thousand cubic feet
of gas showing different mixtures of ethane and methane, at different
Detailed Description of the Embodiments Shown in the Drawing~~s
Dealing first with Figure 1, this shows, for various pressures and the
same temperature, the effect of the addition of ethane to methane. In each
case, the

CA 02205670 1999-03-04
z factor has been calculated for each percentage of ethane from 0 to 40%.
Then, the
lowest calculated z factor has been arbitrarily defined as 0% capacity gain.
Each of the
other results has been plotted as a percentage capacity gain with reference to
the 0%
capacity gain in order to prepare a curve. Curves developed in this way are
given in
Figures 1A to 1 E, for different pressures, with each curve representing the
situation for
one pressure. The temperature represented by each curve is 35°F.
Looking at Figure 1A, it is seen that, for an 800 psia pipeline, the best
packing occurs when the line is filled with pure methane. As ethane is added,
capacity gain percent decreases until there is about 25% ethane in the line.
After this,
the capacity gain begins to increase again, but it does not reach the levels
obtained for
pure methane.
Figure 1 B shows the effect of addition to methane of ethane for a pipeline
at 1,150 psia. Here, the capacity gain steadily decreases from D% ethane to
about 12%
ethane, and then increases again. After approximately 25% ethane, the capacity
is greater than occurred with no ethane at all.
Figure 1 C shows that this effect is even more pronounced when the
pipeline pressure is increased to 1,350 psia. The lowest capacity now occurs
approximately 7%, and mixtures with more than 17% ethane exhibit packing (and
hence, pipeline or storage capacity) gains unattainable with of natural gas or
Figure 1D shows that at 1,675 psia, the lowest capacity occurs at about
5%, and anything over 12% ethane gives a better capacity gain than is
attainable with
natural gas or methane alone. For best results, however, at least 15% ethane
be present.
At 2,140 psia (Figure 1 E) the addition of about 4% ethane gives a benefit,
and the benefit steadily increases all the way up to the point at which the
ethane begins
to separate out in a liquid phase. For best results, however, at least 12%
ethane, and
preferably 15% ethane, should be present.

CA 02205670 1999-OS-21
Figure 1 F shows the effect of the z factor and its product with the average
molecular weight of the gas for gases having various amounts of methane and
(the ethane is shown in the table as "C2") The flow ratio (1lthe root of the
zMW product)
is plitted..
Thus, it will be seen that for pressures above about 1,000 psia better
packing, and hence lower Compression cost and pumping cost for transportation
when increased amounts of ethane are added over a minimum amount which
decreases with increasing pressure. At 1,150 psia (Figure 1 B) about 24%
ethane must
be added to get the same packing effect as the approximately 2% ethane in
natural gas. If more than this amount is added, however, better packing occurs
each addition. As the pressure increases, successively less ethane need be
added to
give better packing (and hence lower transmission costs and compression costs)
with natural gas. Indeed, at .2,140 psia even about 4% ethane shows sonie
although the advantage is of course greater as more ethane is added: v
, Figure 2 shows how the effect changes with .temperature. Even at 800
psia (Figure 2A) there is a capacity increase (i.e. better packing) as
temperature drops,
and the capacity gain is greater the more C2 that is present. However, the
effect is not
nearly as significant as ai: higher pressures. With higher pressure (Figure
2B) the
capacity gain is much greater with temperature, and the improvement in
capacity gain
becomes still greater as increased amounts of ethane are added. Generally,
it is preferred to operate at a relatively low temperature, such as 70°
to -20°F. Higher
temperatures (e.g. up to about 120°F) can be tolerated, but detract
from the benefits
of the invention.
Figure 3 shows horsepower required for different gas mixes of ethane and
methane, through a pipeline at a maximum pressure of 1,740 psia and a minimum
pressure of 1,350 psia. Figures are for a pipeline of 36" in diameter and a
length of
1,785 miles, with pumping stations located every 56 miles. At a throughput of
million, standard cubic feet per day, a mixture of 98% methane and 2% ethane
corresponds to ordinary natural gas) would require 812,579~horsepower.
However, the
same standard volume of gas, but containing 35% C2, can be moved with only

CA 02205670 1997-OS-16
horsepower, for a saving of over 150,000 horsepower. When the throughput is
to 2.5 million standard cubic feet, natural gas containing 2% ethane cannot
be transmitted, because the velocities and temperatures involved are too
However, gas with 6% ethane can be transmitted, and gas with 35% ethane shows
saving of over, 500,000 horsepower over that which is used to transmit the gas
with 6%
Figure 4 shows the effect on horsepower requirements per million cubic
feet of gas being pumped through the same pipeline as used in Figure 3 when
pipeline gas contains different concentrations of ethane at 35°F.
Figure 4 also shows the negative effect of adding ethane to a typical
pipeline running at about 800 psia pressure and 35°F. Required power
for pumping
increases until the mix contains 26% ethane and then decreases for higher
concentrations approaching the liquid phase limits. However, the decrease is
sufficient so that, by the concentration where liquefaction occurs (about 40%)
there is
any saving of horsepower over pumping ordinary natural gas. This energy hill
peaks at decreasing concentrations of ethane as operational pressure
increases, e.g.,
14% at 1,150 psia, 8% at 1,350 psia, 6% at 1,475 psia. This is due to the rate
decrease in the value of the z factor overcoming the rate of increase in
As noted, at 800 psia, increasing the amount of ethane even up to 40%
of the mixture does not produce a saving of horsepower. At 1,150 psia,
however, an
in~;rease of ethane to over about 24% causes a horsepower saving when compared
the values at 2% ethane (which is approximately the amount of ethane in most
gas). At 1,350 Asia, a decrease in horsepower occurs with mixtures containing
than about 14% ethane. As the pressure increases, the horsepower saving occurs
with still less added ethane. As can be seen from Figure 4, the peak
requirement shifts to the left of the graph and becomes smaller as pressure
However, reading Figure 4 with Figure 2A and 2B shows that, as temperature
decreases, the curve tends to rotate to the right. Thus, as temperature
decreases, less
addition of ethane is necessary to obtain the desired additional packing and
decreased compression and pumping energy requirements. The result is lower

CA 02205670 1997-OS-16
compressive power requirements for equivalent volumes of higher B.T.U. gas
than can be achieved with conventional pipeline specification natural gas.
pipeline throughput are able to be economically achieved with these enhanced
mixes with corresponding increases in horsepower.
Similar effects are seen when ethylene is used in substitution for all or part
of the ethane.
When propane, isop,ropane or propylene, or mixtures of any of these
gases, are substituted for all or part of the ethane, the effects are even
pronounced than with ethane, and occur with a smaller addition of each of the
compounds mentioned than was necessary with ethane as noted previously in this
The preferred composition of the resulting gas is as follows:






(BUTANES AND OTHER Not required , but 0% VOLUME

COMPONENTS OF THE amount present in

NATURAL GAS original natural gas
(up to

about 1 %)can be

tolerated if it does

cause separation of

liquid phase at the

pressure and

tem erature used

CA 02205670 1997-OS-16
NITROGEN Not required, but 0% VOLUME

present in the original

natural gas can be

tolerated if below
2% by


CARBON DIOXIDE Not required, but 0% VOLUME

present in the original

natural gas can be

tolerated if below
1 % by






Compositions with hydrocarbon additives outside these ranges generally
are of little economic benefit, or approach 'the limits at which iv~ro-phase
or liquid
behaviour can be seen. Therefore, if mixtures outside these parameters are
used, care
should be taken to avoid conditions which might cause liquid to fall out of
the mixture.
Liquid is generally to be avoided, as it may pool in low areas of a pipeline
and be
difficult to remove. The preferential liquefaction of some components will
also cause
the composition of the gaseous phase of the mixture to change, thereby
changing the
z factor and hence the compressibility of the gaseous phase.
The foregoing has illustrated certain specific embodiments of the
invention, but other embodiments will of course be evident to those skilled in
the art.
Therefore it is intended that the scope of the invention not be limited by the
embodiments described, but rather by the scope of the appended claims.

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 1999-11-16
(22) Filed 1997-05-16
Examination Requested 1998-04-14
(41) Open to Public Inspection 1998-05-18
(45) Issued 1999-11-16
Expired 2017-05-16

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Registration of a document - section 124 $100.00 1997-09-25
Request for Examination $400.00 1998-04-14
Application Fee $300.00 1998-04-20
Advance an application for a patent out of its routine order $100.00 1998-04-21
Registration of a document - section 124 $100.00 1998-07-28
Maintenance Fee - Application - New Act 2 1999-05-17 $100.00 1999-04-23
Final Fee $300.00 1999-08-17
Maintenance Fee - Patent - New Act 3 2000-05-16 $100.00 2000-05-04
Maintenance Fee - Patent - New Act 4 2001-05-16 $100.00 2001-05-02
Maintenance Fee - Patent - New Act 5 2002-05-16 $150.00 2002-03-20
Maintenance Fee - Patent - New Act 6 2003-05-16 $150.00 2003-05-05
Maintenance Fee - Patent - New Act 7 2004-05-17 $200.00 2004-05-03
Maintenance Fee - Patent - New Act 8 2005-05-16 $200.00 2005-05-05
Maintenance Fee - Patent - New Act 9 2006-05-16 $200.00 2006-05-10
Maintenance Fee - Patent - New Act 10 2007-05-16 $250.00 2007-05-09
Maintenance Fee - Patent - New Act 11 2008-05-16 $250.00 2008-03-18
Maintenance Fee - Patent - New Act 12 2009-05-18 $250.00 2009-04-15
Maintenance Fee - Patent - New Act 13 2010-05-17 $250.00 2010-04-27
Maintenance Fee - Patent - New Act 14 2011-05-16 $250.00 2011-05-04
Maintenance Fee - Patent - New Act 15 2012-05-16 $450.00 2012-03-20
Maintenance Fee - Patent - New Act 16 2013-05-16 $450.00 2013-04-16
Maintenance Fee - Patent - New Act 17 2014-05-16 $450.00 2014-04-22
Maintenance Fee - Patent - New Act 18 2015-05-19 $450.00 2015-04-14
Maintenance Fee - Patent - New Act 19 2016-05-16 $450.00 2016-02-25
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
Past Owners on Record
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

To view selected files, please enter reCAPTCHA code :

To view images, click a link in the Document Description column. To download the documents, select one or more checkboxes in the first column and then click the "Download Selected in PDF format (Zip Archive)" or the "Download Selected as Single PDF" button.

List of published and non-published patent-specific documents on the CPD .

If you have any difficulty accessing content, you can call the Client Service Centre at 1-866-997-1936 or send them an e-mail at CIPO Client Service Centre.

Number of pages   Size of Image (KB) 
Representative Drawing 1998-05-29 1 16
Cover Page 1998-05-29 1 47
Abstract 1997-05-16 1 14
Description 1997-05-16 12 588
Claims 1997-05-16 3 72
Drawings 1997-05-16 7 137
Claims 1999-05-18 3 81
Drawings 1999-05-18 7 137
Description 1999-05-21 12 599
Description 1999-03-04 12 597
Claims 1999-03-04 3 81
Drawings 1999-03-04 7 137
Drawings 1999-08-17 7 143
Representative Drawing 1999-11-16 1 14
Cover Page 1999-11-16 1 37
Prosecution-Amendment 1999-03-04 17 730
Prosecution-Amendment 1998-04-21 3 80
Prosecution-Amendment 1998-04-14 1 43
Correspondence 1998-04-20 2 55
Assignment 1997-05-16 4 141
Assignment 1998-07-28 6 125
Prosecution-Amendment 1998-09-04 2 88
Correspondence 1998-11-06 3 68
Fees 2003-05-05 1 28
Assignment 1997-05-16 2 86
Correspondence 1997-07-18 1 30
Assignment 1997-09-25 4 108
Correspondence 1999-07-12 1 99
Correspondence 1999-08-17 3 110
Prosecution-Amendment 1999-05-18 5 167
Prosecution-Amendment 1999-05-21 3 98
Fees 2000-05-04 1 31
Fees 2002-03-20 1 32
Fees 2001-05-02 1 30
Fees 1999-04-23 1 33
Fees 2005-05-05 2 45
Fees 2004-05-03 1 29
Fees 2006-05-10 1 28
Fees 2007-05-09 2 53
Fees 2008-03-18 1 30
Correspondence 1998-11-26 1 13
Examiner Requisition 1999-05-07 2 59
Correspondence 1998-11-26 1 13
Correction Payment 1998-08-13 1 50
Fees 2012-03-20 1 163
Correspondence 2012-12-19 12 839
Correspondence 2013-01-14 1 25