Note: Descriptions are shown in the official language in which they were submitted.
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TANK GAS BUBBLER
FIELD OF THE INVENTION
The present invention relates to a gas bubbler, more specifically for use in
the treatment of waters used in
the oil industry and methods of use thereof.
BACKGROUND OF THE INVENTION
In the oil industry, extraction of oil from oil wells will typically yield in
the range of 30% of the actual
content in the reservoir being exploited. The process of water flooding refers
to the method of injecting
water into a reservoir resulting in an increase in pressure and subsequent
increase in oil extraction. The
flood water is injected into a reservoir and allows to maintain or even
increase the pressure inside the
reservoir and replaced the extracted oil. It also allows to displace oil
within the reservoir and push it
towards a well. The use of flood water allows for more production from a well
and therefore increased
savings by extending the production expectancy of a well.
US2012/0152546A1 describes a process for water treatment specifically for SAGD
operations. There is
described a process which uses chemical oxidation (CO) or electromagnetic
treatment (ET) to destroy or
degrade organics in the produced water. It is stated a primary purpose of the
produced water treatment
steps described above is to provide water of suitable quality to the steam
generator.
US 7694736B2 generally describes a method and system for producing steam for
extraction of heavy
bitumen including the steps of mixing carbon or hydrocarbon fuel. It is stated
that with its simple direct
contact, above ground adiabatic nature, and its high pressure and temperature
solid removal, the invention
will minimize the amount of energy used to produce the mixture of steam and
gas injected into the
underground formation to recover heavy oil. It is stated that the present
invention adds the adiabatic direct
contact steam and carbon dioxide generation unit to reduce the disadvantages
of the prior art and to allow
for expansion with use of a low quality water supply, reject water from
existing facilities and the use of
low quality fuel supplies. Also, there is no need for high quality separation
of the oil from the produced
water and water purification processes with this invention. It is stated that
the mixture produced at the
EOR production well 65 is separated into gas (mainly carbon dioxide and
natural gas), oil and water. The
produced water contains heavy oil remains, dissolve minerals, sand and clay.
The separated low quality
produced water 64 is used for steam generation 61 without any additional
treatment.
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There is a need for a device which effectively removes II2S and other gases
from large volumes of waste
water such as polymer flood waters. The present invention is directed to the
use of a gas bubbler to treat
recovered (or used) polymer flood waters, used in the oil extraction industry.
The polymer flood waters
are being recycled in order to limit water usage and reduce discharge of used
water containing numerous
contaminating compounds.
SUMMARY OF THE INVENTION
Recovered polymer flood waters are found to contain several contaminants which
affect its quality. The
contaminants also impact the amount of polymer used when re-using the
recovered waters. As H2S when
present with oxygen (H2S and 02) have a substantial impact on polymer
degradation up to a 400 ppm or
more polymer required to make the desired viscosity fluid. H2S is one key
contaminant that is efficiently
removed by the bubbler according to the present invention.
Moreover, removal of H2S leads to improved safety and handling of the water
system. The operations
performed downstream from gas removal will be done so under safer conditions
as currently H2S can vent
out of the plant equipment at various locations within the water system
process piping and vessels.
In order to increase the efficiency of the water treatment process and to
allow savings in polymer usage
and therefore economic savings, the use of a gas bubbler has been found to
yield treated water which can
more easily and advantageously be reused in polymer flood water, steam
assisted gravity drainage and/or
alkaline surfactant polymer flood water.
According to an embodiment of the present invention, there is provided a gas
bubbler designed to be used
inside a tank having walls, said tank adapted to receive a liquid to be
treated, wherein said gas bubbler
comprises: at least one inlet; at least one tubing length designed to be
inserted inside the tank; said at least
one tubing length positioned horizontally and defining a plane and wherein
said tubing containing a
plurality of apertures disposed along the tubing underneath said plane, said
apertures facing the walls but
positioned at an angle less than perpendicular to the walls of said tank.
Preferably, the apertures are positioned at an angle ranging from 20 to 60
with respect to the walls.
More preferably, the apertures are positioned at an angle of 45 .
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Preferably, the gas bubbler comprises two inlets and two separate and distinct
tubing lengths spaced apart
from one another each defining a specific plane and where one tubing length is
generally positioned
above the other tubing length.
According to another aspect of the present invention, there is provided a gas
bubbler designed to be used
inside a tank having walls, said tank adapted to receive liquid to be treated,
wherein said gas bubbler
comprises: at least one inlet; at least one tubing length designed to be
inserted inside the tank; said at least
one tubing length defining a plane and wherein said tubing containing
apertures disposed underneath said
plane, said apertures being positioned at a downward angle of 45 in relation
to the walls of said tank.
According to another aspect of the present invention, there is provided a
method for removing H2S from
water used in the oil industry, said method comprising the steps of:
- introducing water requiring degassing into a tank fitted
with a gas bubbler;
- injecting natural gas into the gas bubbler at a ratio of 1:1
natural gas volume injected:
offgas (containing H2S) volume present in the used water; and
- removing the gas extracted at the surface of the water;
said gas bubbler comprising a tubing defining a horizontal plane, said tubing
having apertures disposed
therealong at a 45 angle underneath the plane defined by the tubing.
According to another aspect of the present invention, there is provided a
method for removing H2S from
water used in oil extraction, said method comprising the steps of:
- introducing water requiring degassing into a tank fitted
with a gas bubbler;
- injecting natural gas into the gas bubbler; and
- removing the gas extracted at the surface of the water;
said gas bubbler comprising a tubing defining a horizontal plane, said tubing
having apertures disposed
therealong at a 45 angle underneath the plane defined by the tubing, and
wherein the concentration of
H2S in the water is decreased. Preferably, the concentration of H2S in the
water is decreased to a level
such that results in a 100 ppm to 400 ppm polymer usage reduction.
According to another aspect of the present invention, there is provided a gas
bubbler for use in water
treatment in the oil industry, said gas bubbler adapted to be used inside a
tank having walls, wherein said
gas bubbler comprises:
- at least one inlet;
- a loop made of at least one tubing length designed to be inserted inside
the tank;
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said loop being positioned horizontally and defining a plane and wherein said
tubing containing a
plurality of apertures disposed along the tubing underneath said plane, said
apertures facing the walls at a
450 angle. Preferably, the gas bubbler is positioned at a lower portion of the
tank and around the inside
perimeter of the tank.
Preferably also, the tubing is positioned at a distance ranging from a third
of the length of the radius of the
tank to half of the length of the radius of the tank.
Preferably, the gas bubbler comprises an upper loop and a lower loop, wherein
the upper loop is
positioned generally directly above the lower loop.
The tank gas bubbler according to a preferred embodiment of the present
invention is made of linear
tubing, positioned in an horizontal plane, comprising holes positioned to be
at a 450 downward angle
towards the walls of a tank in which it is inserted. It has been determined by
the inventor that the above
specification would allow for increased removal of H2S present and other gases
from the waters to be
treated. The gasses are removed as they have been shown to have deleterious
effects on polymers used in
polymer flood waters.
According to a preferred embodiment of the present invention, the gas bubbler
used in the treatment of
polymer flood waters allows to effectively remove H2S from the sour saline
(grosmont) and produced
waters which, in turn, improves the polymer loading for subsequent polymer
flood treatment. This leads
to substantial savings in polymer usage to meet viscosity target.
The tank gas bubbler can be used for any water fluid requiring removal of
gasses, such as H2S, from a
system. This, in turn, greatly improves the downstream safety of fluid
handling having reduced H2S
levels. Another advantage of the tank gas bubbler according to the present
invention is that the installation
is simple and cost efficient and can be adapted to accommodate wide ranges of
water:gas rates. The
piping sizes can vary when used in this design to meet the rigorous process
conditions and be adapted for
any tank size. It is worth noting that the process controls based on water
flow to gas flow rates ratio s
control program.
The use of a tank gas bubbler according to the present invention can lead to
reductions in polymer usage
ranging from 100 to 400 ppm over standard reuse of polymer flood waters when
conducting polymer
flood water operations.
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=
The spacing between apertures on the tubing and the size of the apertures is
dependent on the tank size
(i.e. total volume) as well as the type of liquid being treated (i.e. the
content of gas to be extracted) and
=
the flow rate of the gas being used in the operation.
In one embodiment according to the present invention, the apertures were
located 12 inches apart on %
inch stainless steel tubing and had a diameter of 1/8 inch.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 is a schematic representation of a process using the gas bubbler
according to a preferred
embodiment of the present invention where the produced water is treated to be
reused as polymer flood
water.
Figure 2 is a schematic representation of a process using the gas bubbler
according to a preferred
embodiment of the present invention where the produced water is treated to be
reused in steam assisted
gravity drainage operations.
Figure 3 is a schematic representation of a process using the gas bubbler
according to a preferred
embodiment of the present invention where the produced water is treated to be
reused in alkaline
surfactant polymer flood water.
Figure 4 is a perspective view of the double loop gas bubbler according to a
preferred embodiment of the
present invention inserted into a cylindrical tank.
Figure 5 is a front view of a tubing length of the gas bubbler according to a
preferred embodiment of the
present invention.
Figure 6 is a view of the cross-section of a tubing length of the gas bubbler
according to a preferred
embodiment of the present invention.
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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
The invention will be better understood by referring to figures which
illustrate preferred embodiments
thereof. In Figure 4, the tank square double loop gas bubbler according to an
embodiment of the present
invention and used in the treatment of polymer flood water was made of linear
tubing. The two loops
overlapping each other and positioned in a horizontal plane, comprising holes
positioned to be at a 450
downward angle towards the walls of a tank in which it is inserted. It was
determined by the inventor that
the above specification would allow for substantial and efficient removal,
from the waters to be treated, of
H2S present and other gases which have deleterious effects on polymers used in
polymer flood waters.
According to one embodiment of the present invention, a double loop gas
bubbler as shown in Figure 4 is
provided for insertion into a tank of 2000 bbl capacity. The gas bubbler is
positioned inside a tank so that
the lower loop is located at 12 to 18 inches from the bottom of the tank. The
gas bubbler is preferably
installed so that the first tube (lower tube) is at a distance of
approximately 1 - 1.5 feet off of the bottom
floor of the tank. The second tube (upper tube) is installed approximately 10
inches to 1.0 feet vertically
above the lower. Of course, the distance can be modified as one of the factors
that need to be considered
in the determination of this distance include gas flow rate. A person skilled
in the art could consider
adapting the system to include additional tubes depending on the tank size or
gas volumes.
The distance inside a tank between the loops of the gas bubbler and the
interior walls of the tank depends
on the tank size but is preferably located at a distance equal to the radius
of the tank divided by 2 or radius
of the tank divided by 3.
In one embodiment of the present invention, the tubing of the gas bubbler is
made of 3/4 inch stainless
steel with apertures at every 12 inch and positioned at 45 facing downward
towards the walls of the tank.
The instrumentation that was used in the experiments included the following:
pressure transmitters (one
for the tank and one for the gas line downstream of the flow valve); a
pressure control valve (model: 4
inch Globe Valve 150# rating; 0 to 20,544 m3/day rate); inlet gas ESDV valve
(model: 2 inch valve 150#
rating; 0 to 10000 m3/day); flow control valve (model: D body ¨ Globe 1 inch
body ¨3/4 inch; 150# rating;
0 to 10000 m3/day); and flow meters (rotameter or turbine) (model: Rosemount 0
to 10 e3m3/day).
The tubing material used was Dual-Certified P8 316/316L Austenitic Stainless
Steel. The inspection
performed included a 100% visual inspection on all welds, 100% RI of the
entire circumference on all
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butt welds. 100% LPI of all welds that were not radiographic tested. Ferrite
measurements were
performed on 5% of all butt welds. There is at least one ferrite test per
welder/WPS/brand
consumable/wall thickness. All fabricated piping was hydrotested for a minimum
of one hour.
The gas bubbler tube used 316 L SS material for corrosion protection from sour
fluids. The diameter of
pipe depends on the gas flow rate to meet the pressure drop calculations.
Trials were conducted using 1/2
inch diameter size up to 1.5 inch size. However, a person skilled in the art
would know that he could use
larger tubing depending on the equipment used and the requirements for gas
flow rate and distribution.
The tested parameters to indicate improvement in the water in terms of H2S
content was determined by
testing the inlet H2S ppm in the inlet water versus the outlet H2S in the
effluent water.
The spacing between apertures on the tubing and the size of the apertures is
dependent on the tank size
(i.e. total volume) as well as the type of liquid being treated (i.e. the
content of gas to be extracted) and
the flow rate of the gas being used in the operation.
The distance between holes (apertures) and the diameter of holes on the tubing
and flow rate of the gas
injected is determined based on the diameter of the tubing and of the holes.
Both 1/16 inch holes and
118th inch hole sizes were trial tested. The advantage of the Ye inch holes
size was that they were easier
to drill.
The distance between holes (apertures) depends on the required surface area
for the required gas injection
volume ¨ based on pressure drop calculations
Total # of holes = (required surface area / hole size area)* 3.0
Distance between holes on each tube line =
length of each tube line / (total # of holes / 2 (# of tubes))
The amount of overlap between the upper and the lower tubes (in the case of a
double loop gas bubbler)
covered a distance of about V2 to 3/4's of the way back to the inlet area
where the tubes split. Trials were
performed using the shorter 1/2 length and the longer 3/4 length overlap.
However, the overlap may be more
or less given other parameters including, but not limited to, gas flow rate,
tank size.
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Some of the advantages of using a double loop bubbler include the ability to
reduce the 112S that normally
stays entrained in the water in systems. Also, it is believed that since the
gas injected bubbles outward
towards wall of the tank, because of the use of holesat a 45 degree angle,
there is created a substantial
agitation and swirling of the fluid present in the tank.
Preferably, the gas bubbler is inserted and secured within the tank through
the use of support angle irons,
footings, and wire with clamps to support to hold suspended in the tank fluid
space ¨ attached to nozzles
across tank to hold in place if available in the tank.
Preferably, the flow rate of the gas is matched to a 1:1 gas volume rate to
the sour flashing gas volume
rate off the water rate
The present invention can be better understood by referring to the figures.
Figure 4 is a perspective view
of the invention (the double loop gas bubbler) which is inserted in a
cylindrical tank (note the dashed
outline, as well as the entry point of the tube into the tank.
In the preferred embodiment illustrated in Figure 4, the gas bubbler (505) is
positioned inside a tank (500)
having a cover (502) and an outlet (501) for the gas extracted. The valve
system (540) allows the gas to
reach the gas bubbler (505) tubes (510) through a common inlet line (550) that
splits into the two lines of
the double loop: the upper loop (520) and the lower loop (530). The inlet flow
control valve (not shown)
can be equipped with a pressure override ¨ gas flow meter ratio control back
to the inlet water flow rate
and water gas GWR (gas water ratio). When in operation, gas such as natural
gas will be injected into the
tank (500) via the inlet (550) and will circulate through the tubing (510)
into the upper (520) and lower
loop (530). Once the gas in the liquid reaches the top of the tank it is
removed from the tank through a gas
outlet (501).
Figure 5 is a simple cross-sectional view of the tubing (510) used in the gas
bubbler (405) which shows
the aperture (511) within the tube at an angle of 45 facing downwards. The
tubing (510) is positioned
inside the tank horizontally defining a plane (600) underneath which the
apertures (511) are positioned for
increased gas removal.
Figure 6 is a perspective view of a tubing (510) segment as used in an
embodiment of the gas bubbler
(505) according to the present invention. The apertures (511) are located
beneath the horizontal plane
(600).
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The process according to the present invention is intended for use in treating
various used waters
reclaimed from operations in the oil industry, more specifically, polymer
flood waters, SAGD waters and
alkaline surfactant brine waters, for their subsequent reuse.
The use of a tank gas bubbler can lead to reductions in polymer usage for
subsequent polymer flooding
activities ranging from 100 to 400 ppm when conducting polymer flood water
operations.
Polymer Flood Water Treatment
The polymer flood water treatment unit incorporating a gas bubbler according
to an embodiment of the
present invention, may also comprise an inlet mixing/solids tank with a gas
bubbler; an electrocoagulation
unit; a solids removal/handling system; one or more multimedia filtration
units; and one or more chemical
injection systems.
The polymer flood water treatment unit incorporating a gas bubbler according
to another embodiment of
the present invention, may comprise an inlet mixing/solids tank (without a gas
bubbler); an
electrocoagulation unit; a solids removal/handling system; one or more
multimedia filtration units; and
one or more chemical injection systems.
An advantage of using a gas bubbler according to a preferred embodiment of the
present invention is the
removal of H2S from the polymer produced and makeup water streams. H2S and 02
have a substantial
impact on polymer degradation. Moreover, there is improved safety and handling
of the water system, i.e.
safer for operations when there is no H2S venting from the plant equipment.
Processing used waters leads
to selective ion removal from water streams to reach the desired water
specification. There is also bacteria
removal from water, since bacteria consume polymer that is added to the flood
water ¨ require no
bacteria for potential future CDG gels if gels were to be used in future
instead of polymers. It is worthy of
mention that the process described herein allows for the removal of oil and
grease residual from water as
well as reducing the total dissolved solids (TDS) of the water each time it is
processed. The intent is to
have lower TDS in the water stream for SAGD future water requirements. As
benign water is created
there are subsequent savings on materials for construction of pipelines and
polymer hydration and
injection facilities. The process leads to the creation of a stable polymer
when using a treated water
stream; solids removal from water streams - incoming solids from makeup waters
i.e. grosmont solids
handled at one location versus the multiple solids deposition locations; and
ability to blend the polymer
produced water and makeup water streams prior to treatment system ¨ optimized
with mixing.
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The H2S and 02 reaction consumes polymer very aggressively and we found that
by reducing or removing
the H2S from the fluid this reaction does not occur so rapidly, therefore one
is capable of reducing the
amount of polymer usage with lower H2S in the fluid.
Another advantage of the treatment process according to an embodiment of the
present invention is the
reduction ranging up to 850 to 1000 ppm of polymer required for flood water.
Another advantage of the treatment process is the removal or deactivation of
the NORMS (naturally
occurring radioactive materials) that are present in the sour saline grosmont
water stream. The treatment
process removes the norms from the water precipitating with the solids sludge
stream that is created. This
makes the effluent treated water stream safer for handling for operations and
will decrease the norms
contamination levels of the downstream equipment. This also makes the sludge
disposal costs cheaper as
it costs 6 times more to dispose of NORMS contaminated sludge.
Polymer Flood Water Specification
The water specification for polymer hydration was determined through field
pilot scale testing at a rate of
275 m3/day.
One of the benefits of having determined a polymer flood water specification
is to optimize the polymer
consumption to meet the desired viscosity targets with the least amount of
polymer use. Another benefit is
the determination of optimal pH range for the polymer to function most
efficiently. It also allows the
analysis of other water sources and the determination of the most appropriate
water treatment process
required to allow the water to be used in the polymer systems. Further, it
allowed the determination of the
factors having the greatest impact on polymer loading, such as calcium
content, pH, H2S, 02, and solids
content. An advantage of having determined a polymer flood water specification
allowed reaching a
reduction in polymer usage ranging from 850 to 1000 ppm for floodwater uses.
Polymer Flood Water Pilot
In a pilot trial that was conducted, the five (5) main water streams that were
tested in multiple equipment
configurations to achieve electrocoagulation and filtration/chemical treatment
during the pilot were Grand
Rapids, Quaternary, Sour Saline Grosmont, North Brintnell 7-27 produced water
and a 50/50 blend of the
sour saline grosmont and produced water streams. Polymer loading prior to the
implementation of the
processes described herein averaged 2200 ppm.
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The pilot allowed to determine a water specification for polymer flooding
activities and helped in finding
a more economical water treatment process that provided lower polymer loading.
Elemental analytical
results from the electrocoagulation testing were analyzed to determine the
impact of each element on the
polymer loading.
The following desired or preferred water specification for polymer floodwater
was determined as a result
of the pilot conducted:
Element Water Spec
pH 8.5 ¨ 10.5
Calcium <20 ppm
Magnesium 100¨ 220 ppm
Total Hardness as CaCO3 400¨ 800 ppm
TDS 15000 - 25000 ppm
H2S <50 ppm
02 < 50 ppb
Sulphide <60 ppm
Sodium 6000 - 9000 ppm
Total alkalinity 1500 ¨ 2500 ppm
Turbidity <100 NTU
TSS <250 ppm
Iron <1 ppm
For the Brintnell waters tested, it was determined that the following
parameters impacted the polymer
loading the most:
- pH < 9.0 or pH > 10.5, had an impact of about 200 - 300 ppm polymer
loading
increase
- H2S and 02 reaction, - H2S > 50 ppm and 02> 50 ppb, had an impact of
about 400 -
800 ppm polymer loading increase
- solids - TSS (total suspended solids) > 250 ppm, had an impact of up
to 500 ppm in
polymer loading increase
- calcium ion > 20 ppm, had an impact of up to 400 - 500 ppm in polymer
loading
increase.
- Total hardness level of 0 ppm (no calcium or magnesium present) ¨ increased
the
polymer loading by 200¨ 300 ppm.
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From the trial results, it was determined that a tank gas bubber followed by
electrocoagulation (EC) water
treatment process; then followed by multimedia filtration (MMF) provided
optimal efficiency with
respect to polymer loading in comparison to all other configurations. The
combination of tank gas
bubbler/EC/MMF decreased polymer loading up to 1050 ppm range on all waters
tested, when all fluids
were adjusted to a pH range of 9.0 - 9.5.
Three other process steps resulted in improved polymer loading. The savings
noted for each individual
process enhancement and cannot be necessarily combined for cumulative savings.
These three other
processes involved a gas bubbler, a nitrogen blanket, and fresh water for
mother solution hydration. The
utilization of a gas bubbler in the water inlet tank to degas out the gases
H2S and CO2 from the water
resulted in polymer loading savings of up to 400 ppm. The use of a nitrogen
gas blanket on the polymer
mixing and aging tank in polymer injection skid resulted in polymer loading
savings of up to 300 ppm.
The use of fresh water to hydrate the polymer mother solution resulted in an
additional polymer loading
savings of up to 300 ppm.
Cumulatively when creating the overall required polymer water specification
mixture for injection, the .
testing found that one could also use treated produced water blended with some
fresh water (with tank gas
bubbler/EC/MMF treated water being used for the blend water and fresh water
being used for polymer
mother solution hydration) which resulted in an additional 175 ppm in polymer
savings ¨ total polymer
usage decreased from 1050ppm down to 875 ppm polymer loading
A separate system containing only filtration and chemicals was also tested for
comparison to the tank gas
bubbler/electrocoagulation/multimedia unit. Filtration and chemicals provided
polymer reduction but this
reduction was lower at around 400 ppm. Although this alternate system was very
effective as the
filtration and chemical treatment utilizing ceramic Macrolite media with
chlorine and sulphite added
were able to break up and remove the oil and grease, polymer, and solids from
the waters effectively and
reduced turbidity of the waters.
Additionally, for direct comparison to the electrocoagulation unit, the use of
Dow RSC resin was tested to
see if could remove NORMS with the resin product in a filter vessel. The Dow
resin tested allowed for
the reduction of radium levels in the waters by 36 to 59 % removal of inlet to
outlet stream.
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=
The process incorporating a gas bubbler according to a preferred embodiment of
the present invention is
described with reference to specific processes illustrated in Figures 1 ¨3 and
described in Examples 1 to
3 below.
Example 1 - Polymer Flood Water Treatment Process
In a process to treat polymer flood waters used in oilfields for eventual
reuse, there is provided the
following steps which incorporate the use of a gas bubbler according to a
preferred embodiment of the
present invention:
1) Polymer flood water flows (5) into a cone bottomed storage tank (10) (or
other mechanical
separation equipment which may be equipped with an oil skimmer at the top of
the tank or
overflow or oil removal standpipe) where the solids (16) are removed from
fluid as needed; and
the oil (17) is skimmed off of the storage tank (10) as needed.
2) When the resulting fluid (15) shows signs of being sour (H2S is present),
it flows into a tank
which is equipped with a double loop square gas bubbler inside (20) and gas
(23) (like natural
gas) is bubbled into the storage tank fluid reservoir as the fluid flows
in/out of the tank (20). This
permits the stripping out of H2S and other gases (27) present in the fluid.
Natural gas volume is
added at a 1 to 1 ratio to the fluid offgas volume.
3) If the resulting fluid (25) requires additional oil removal prior to water
treatment then a single or
two stage polymer packing vessel (30) for oil adsorption/coalescence (37) are
used (like
Mycelx6).
4) If the resulting fluid's (35) oil and grease level is sufficient, then the
fluid (35) is pumped and
undergoes a pH adjustment (40)(if necessary) where the pH is raised in the
fluid by adding a
chemical (like caustic - sodium hydroxide (43)).
5) The fluid (45) is then sent through an electrocoagulation unit (50) ¨ a
closed cell design (like
Waveionics ) this prevents gases from being released into the atmosphere
during the step. The
electrocoagulation step consists of metal plates with electrodes that are
electrified as the fluid
passes through the cell. During the step of electrocoagulation, the metal
plates are consumed and
the metal precipitates with the water solids (57).
6) Subsequently, there is another step of chemical addition (60) where
additional chemicals (63) like
caustic and coagulant, are added to the fluid (55) to assist with solids
removal (67) by further
raising the pH and promoting precipitation or agglomerating the particles
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7) If necessary, the fluid (65) undergoes another step of bulk solids removal
stage (70)(with a cone
bottomed tank and/or solids clarifier) is performed with oil recapture (77) if
applicable.
8) The resulting fluid (75) is sent to a cone bottomed tank (80) for surge
volume and additional
solids removal (86) and oil capture (87), if applicable.
9) The resulting fluid (85) is then pumped through multimedia filtration
(90)(like ceramic media
such as Macroute ) in single or double filtration stages removing solids, oil
and polymer (97).
10) If fine micron particle size is required then the fluid (95) is sent
through bag filtration units (100)
in single or double follows the multimedia filtration with filtration bags
(such as 3M DuoFLO
followed by absolute 3M pillow bags)
11) The resulting fluid (105) is then sent into storage tanks (110) for
further use.
12) From the storage tank the treated fluid may be pumped and sent to a main
blend line and may also
be sent to the polymer mixing system.
13) A polymer mixing system is typically used to create a thick mother
solution and utilizes a
softened fresh, raw fresh, or treated produced water supply for the hydration
of the polymer prior
to being blended into the main blend fluid stream.
14) The combined polymer water and blend water is then mixed to the desired
viscosity and is
injected into the wellbore.
It is preferable to use solids capture and separation system (such as, but not
limited to, cone bottom tanks)
so that solids can be removed from the water during the process.
The treated water to be used from storage tanks to send backwash water to the
filtration units and water
treatment as required must preferably meet the desired backwashing and water
properties for treatment.
Preferably, gas blanketing is desired on the process tanks and vessels to
ensure that there is no oxygen
ingress into the fluid.
A tank vapour recovery system is preferred to capture the offgases from the
process.
Example 2 ¨ Steam Assisted Gravity Drainage (SAGD) or Cyclic Stimulation Steam
(CSS) Thermal
Water from Polymer Flood Water Treatment
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If the TDS of the polymer flood returns water has reduced to the desired
levels after treating the fluids
with the process discussed in Example I then additional equipment can be added
downstream of the
process to make the water acceptable for thermal steam flood usage. The
desired or preferred water
specification for thermal steam flood usage is set out below:
Element Water Spec
pH 8.5 ¨ 10.5
Calcium <0.1 ppm
Magnesium <0.1 ppm
Total Hardness as CaCO3 <0.5 ppm
TDS <12000 ppm
H2S 0 ppm
02 < 10 ppb
Sulphide
Sodium <9000 ppm
Total alkalinity <700 ppm
Turbidity <2 NTU
TSS <1 ppm
Iron <0.5 ppm
In a process to treat polymer flood waters used in oilfields for eventual
reuse in Steam Assisted Gravity
Drainage (SAGD) or Cyclic Steam Stimulation (CSS) thermal water, there is
provided the following steps
which incorporate the use of a gas bubbler according to a preferred embodiment
of the present invention
which will be better understood by referring to Figure 3:
1) Process fluid (5) recovered from polymer flood activities flows into a cone
bottomed storage tank
(10) (or other mechanical separation equipment equipped with an oil skimmer at
the top of the
tank) where the solids (16) are removed from fluid as needed; and oil (17) is
skimmed off from
the storage tank as needed.
2) When the resulting fluid (15) shows signs of being sour (H2S is present),
the tank is equipped
with a double loop square gas bubbler inside (20) and gas (23)(like natural
gas) is bubbled into
the storage tank fluid reservoir as the fluid flows in/out of the tank. This
permits the stripping out
the 112S and other gases (27) present in the fluid. Natural gas volume is
added at a 1 to 1 ratio to
the fluid offgas volume.
CA 02848440 2014-04-08
3) Then, follows a step of oil removal (30) prior to water treatment ¨ fluid
(25) flows through a
single or two stage polymer packing vessel(s) for oil adsorption/coalescence
(37) if such step is
necessary required (like Myceix ) ¨ there is recovery of an oil stream.
4) If the resulting fluid's (35) oil and grease level is sufficient, then
the fluid (35) is then pumped and
the pH is raised in the fluid by adding a chemical (like caustic - sodium
hydroxide (43)) if pH
adjustment (40) is needed.
5) The fluid (45) is then sent through an electrocoagulation unit (50) ¨ a
closed cell design (like
Waveionics ) this prevents gases from being released into the atmosphere
during the step. The
electrocoagulation step consists of metal plates with electrodes that are
electrified as the fluid
passes through the cell. The metal plates are consumed and the metal
precipitates with the water
solids (57).
6) Then, what follows is another step of chemical addition (60) where
additional chemicals (63) like
caustic and coagulant, are added to the fluid (55) to assist with solids
removal (67) by further
raising the pH and promoting precipitation or agglomerating the particles
7) Then, a chemical addition step is performed (370) where a chemical (like
phosphate or lime)(373)
is added to the fluid (65) to remove additional hardness (calcium and
magnesium) (377) not
removed by the electrocoagulation step above.
8) The fluid (375) then undergoes a bulk solids removal stage (380)(through
the use of a tank like a
cone bottomed tank and/or solids clarifier) where solids (386) are removed and
oil (387) is
recaptured, if applicable.
9) If necessary, the fluid (385) undergoes another bulk solids removal
stage (390Xthrough the use of
a tank like a cone bottomed tank and/or solids clarifier) where solids (396)
are removed and oil
(397) is recaptured.
10) The resulting fluid (395) is then pumped through multimedia filtration
step (400)(like ceramic
media Macroute ) in single or double filtration stages
11) If fine micron particle size desired is not attained, then the fluid (405)
is sent through bag
filtration units (410) in single or double with filtration bags (like the
nominal 3M DuoFLO
followed by absolute 3 M pillow bags).
12) After filtration, the resulting fluid (415) will undergo a double pass
reverse osmosis (420) which
is performed with membranes in series. The waste stream, concentrated RO
reject, from the RO
system then needs to go to an evaporator to remove the contaminants, like
alkalinity and silica,
and reduce the overall waste volume. The resulting fluid (425) then flows into
storage tanks
(430) for future usage such as to make steam.
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CA 02848440 2014-04-08
Alkaline Surfactant Polymerf ASP) or Alkaline Surfactant Brine Polymer (ASBP)
Flood Water Treatment
The following desired or preferred water specification for alkaline surfactant
polymer (ASP) or alkaline
surfactant brine polymer (ASBP) flood water was determined from laboratory
small scale fluid testing
and was further implemented onsite:
. ___________________________________________________ .
Element ' Water Spec ,
pH 7.5 ¨ 13.0
Calcium <10 ppm
Magnesium <10 ppm
Total Hardness as CaCO3 30 - 70 ppm
TDS 8000 - 25000 ppm
H2S 0 ppm
02 < 50 ppb
Sodium <8500 ppm
Total alkalinity <5000 ppm
Turbidity <10 NTU
TSS <20 ppm
Iron < 1 ppm
The site produced water is being treated with oil removal system and water
treatment system as listed
below in Example 1
The goal was to confirm the water specification for alkaline surfactant
polymer (ASP) or alkaline
surfactant brine polymer (ASBP) flooding activities determined in laboratory
and help in finding a more
economical water treatment process. It is estimated that the use of a process
of treating ASP or ASBP
polymer flood produced water prior to its reuse for the same purpose can yield
reductions ranging from
200 to 400 ppm in the polymer usage.
Alkaline Surfactant Polymer (ASP) or Alkaline Surfactant Brine Polymer (ASBP)
Flood Water Spec
The alkaline surfactant polymer (ASP) or alkaline surfactant brine polymer
(ASBP) water specification
for polymers for hydration was determined through field pilot scale testing at
a rate of 450 m3/day.
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CA 02848440 2014-04-08
Mycelx oil water separator; a Myeelx backwash vessel; at least one
multimedia filtration unit (more
preferably, in double train of dual multimedia filter vessels in series);- a
double train primary/polisher
strong acid cation ion exchange vessels with brine and caustic reagent step,
and one or more of chemical
injection systems.
Some advantages of using a process incorporating a gas bubbler according to a
preferred embodiment of
the present invention for the preparation of an alkaline surfactant polymer
(ASP) or alkaline surfactant
brine polymer (ASBP) flood water include: the removal of H2S and other gases
like CO2 by the tank gas
bubbler (optional), the removal and recovery of oil from the ASP or ASBP
polymer produced water
stream and the creation of a sales oil stream with the Mycelx green polymer
packing technology vessels
COWS and BW) - revenue from sales oil stream; the removal of the solid
particles from the water stream
with filtration; the removal of the hardness from the water with strong acid
cation resin exchangers down
to 5 ¨ 10 ppm leakage (designed for some hardness leakage); the removal of the
polymer, silicates, and oil
and grease from the strong acid cation resin and multimedia filters with the
addition of a caustic
regeneration cycle step ¨ to remove key foulants of other ASP polymer flood
systems resins and medias;
the savings on polymer loading, facilities and downhole scaling of lines and
injection wells which
translates into less downtime and less wellbore workover costs; and the
reduced cost of softening ¨ i.e.
SAC/SAC regeneration with caustic step added to the brine step is cheaper than
currently used WAC
(weak acid cation) regeneration chemicals of acid and caustic; and the
creation of a liquid waste to be
disposed of from strong acid cation ion exchange softeners versus other
technologies that may create a
solids waste and liquid waste to deal with.
It is estimated that the use of a process of treatment of polymer flood water
incorporating a gas bubbler
according a preferred embodiment of the present invention can yield reduction
in 200 to 400 ppm of
polymer usage which is substantial given the cost of polymer and the amounts
of water treated. These
savings can amount to several million dollars yearly on a large scale project.
By having an optional chemical addition step at the end of the water treatment
process one can adjust the
conductivity of the fluid with brine to reduce amount of alkaline required for
best surfactant activity.
The way to pretreat ASP or ASBP polymer flood water according to an embodiment
of the present
invention, allows one to utilize produced water for polymer mixing and
reinjection versus disposal and
using makeup waters.
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Example 3 ¨ Alkaline Surfactant Polymer (ASP) or Alkaline Surfactant Brine
Polymer (ASBP) Flood
Water Treatment
The polymer flood water treatment unit to yield water for eventual reuse in
ASP or ASBP Polymer Flood
Water, incorporates a gas bubbler according to an embodiment of the present
invention, may also
comprise a Mycelx oil water separator; a Mycelx backwash vessel; at least
one multimedia filtration
unit; a double train primary/polisher strong acid cation ion exchange vessels
with brine and caustic
regeneration step, and one or more chemical injection systems.
In a process to treat alkaline surfactant polymer (ASP) or alkaline surfactant
brine polymer (ASBP) flood
water used in oilfields for eventual reuse, there is provided the following
steps, which incorporate the use
of a gas bubbler according to an embodiment of the present invention, the
process will be better
understood by referring to Figure 2:
1) Process fluid (5) recovered from polymer flood activities flows into a cone
bottomed storage tank
(10) (or other mechanical separation equipment equipped with an oil skimmer at
the top of the
tank) where the solids (16) are removed from fluid as needed; and oil (17) is
skimmed off from
the storage tank as needed.
2) When the resulting fluid (15) shows signs of being sour (H2S is present),
the tank is equipped
with a double loop square gas bubbler inside (20) and gas (23)(like natural
gas) is bubbled into
the storage tank fluid reservoir as the fluid flows in/out of the tank. This
permits the stripping out
the H2S and other gases (27) present in the fluid. Natural gas volume is added
at a Ito 1 ratio to
the fluid offgas volume.
3) Then, follows a step of oil removal (30) prior to water treatment¨ the
fluid (25) flows through a
single or two stage polymer packing vessel(s) for oil adsorption/coalescence
(37) if such step is
necessary (like Myceix ) ¨there is recovery of an oil stream.
4) The fluid (35) is then pumped through multimedia filtration (90)(like
ceramic media Macroute )
in single or double filtration stages:
a. Oxidant Chemical (91)(like bleach) is added upfront of filters to reduce
fluid viscosity
(destroy the remaining polymer) and to kill bacteria;
b. Coagulating Chemical (92Xlike polyaluminum chloride PAC) is added
upfront of filters
to coagulate particles which aids in the filtration; and
c. Reducing Chemical (93)(like sulphite) is added in downstream of first
filter (upfront of
second filter) to remove the oxidant chemical residuals (i.e. consume the
bleach, if
present);
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d. There is a filter backwash step to include an additional step of addition
of alkaline
chemical (94)(like caustic) for polymer, silica, and oil removal from the
filtration media;
5) Then, the fluid (115) passes through a shearing stage (120) of a
inline static mixer followed by an
inline jet nozzle and into a storage tank;
6) Then, the fluid (125) is pumped through anion exchangers (130), two strong
acid cation resin
vessels in series called SAC/SAC,
a. Due to the higher fluid total dissolved solids, the SAC/SAC is designed to
leak from 5
ppm to 10 ppm hardness (calcium and magnesium) in effluent - to not achieve
normal 0
ppm hardness leakage.
b. Optionally, it has an additional alkaline chemical injection step (like
caustic) as part of
the regeneration cycle ¨ the alkaline chemicals are being utilized to remove
polymer,
silica, and oil from the strong acid cation resin beads.
7) In the event that fine micron particle size is desired, then the fluid
(135) flows through bag
filtration units (100) in single or double will follow the anion exchangers
(130) with filtration
bags (like the nominal 3M DuoFLO followed by absolute 3M pillow bags)
8) The resulting fluid 145 is then sent into a storage tank (140).
9) From the storage tank (140), the fluid (145) is pumped and chemicals 143
(like caustic,
surfactant, brine, and polymer) are added to create the required alkaline
surfactant polymer (ASP)
or alkaline surfactant brine polymer (ASBP) mixture (155) to be injected
downhole. In alkaline
surfactant brine polymer (ASBP) the brine is added to increase the
conductivity and reduce the
alkaline volume required for the overall alkaline surfactant brine polymer
mixture.
10) A polymer mixing system (150) is used to create a thick mother solution
and utilizes a softened
fresh (175), raw fresh, or treated produced water supply (5) for the hydration
of the polymer (165)
prior to being blended into the main chemical fluid stream (155).
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