Note: Descriptions are shown in the official language in which they were submitted.
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POLYMER FLOOD WATER TREATMENT FOR REUSE
FIELD OF THE INVENTION
The invention relates to a method for treating polymer flood waters and flood
waters used in oil industry
operations for the subsequent reuse thereof and., more specifically, to the
removal of compounds that impact
the efficiency of polymers used in these types of applications.
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 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 the extending the
production expectancy of a well.
US2012/0152546A1 describes a process for water treatment specifically for SAUD
operations. There is
described a process which uses chemical oxidation (CO) Of 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 suitablCquality 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 63 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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SUMMARY OF THE INVENTION
Given the prior art, there is a need for an efficient and low cost process for
the treatment of polymer flood
and water flood waters. Accordingly, one object of the present invention
provides for a process for the
treatment of polymer flood water for subsequent reuse thereof, said process
comprising subjecting the water
to:
1) a mechanical separation step;
2) a fluid degassing step;
3) optionally, a fluid shearing step;
4) optionally, a second oil removal step;
5) a pH adjustment step, if necessary;
6) an electrocoagulation step;
7) an addition of chemical step for solids removal;
8) a third mechanical separation and oil removal step;
9) a filtration step, preferably by a method such as a multimedia filtration
step or spiral filter;
and
10) optionally, a bag filtration step.
According to another object of the present invention, there is provided a
process for the treatment of polymer
flood water for subsequent reuse for SAGD or CSS thermal water systems
thereof, said process comprising
subjecting the water to:
1.) a mechanical separation step;
2) a fluid degassing step;
3) optionally, a second oil removal step;
4) a pH adjustment step, if necessary;
5) an electrocoagulation step;
6) an addition of' chemical step for solids removal;
7) a third mechanical separation and oil removal step;
8) a filtration step, preferably by a method such as a multimedia filtration
step or spiral filter;
and
9) optionally, a bag filtration step;
10) an addition of chemical for additional hardness removal;
11) a reverse osmosis step; and
12) optionally, an evaporation step to reduce waste volumes.
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According to yet another aspect of the present invention, there is provided a
process for the treatment of
polymer flood water for use in alkaline surfactant polymer (ASP) alkaline
surfactant brine polymer (ASBP)
flood water, said process comprising subjecting the water to:
1) a mechanical separation step;
2) a fluid degassing step;
3) a second oil removal step;
4) a multimedia filtration step comprising the addition of chemicals for fluid
viscosity
reduction, and coagulation of particles present;
5) a step of chemical. addition for solids removal;
6) optionally, a :fluid shearing step;
7) optionally, a water softening step by pumping the water through ion
exchangers;
8) optionally, a bag filtration step; and
9) optionally, a chemical addition step to adjust the conductivity with brine,
According to yet another aspect of the present invention, there is provided a
process for the treatment of
polymer flood water, said process comprising subjecting the water to:
1) a blending step with at least another water from. a different source;
2) a. mechanical separation step;
3) a fluid degassing step;
4) optionally, a fluid shearing step;
5) optionally, a second oil removal step;
6) a pH adjustment step, if necessary;
7) an electrocoagulation. step;
8) an addition of chemical step for solids removal;
9) a third mechanical separation step and oil removal step;
10) a filtration step, preferably by a method such as a multimedia filtration
step or spiral filter;
and
ii) optionally, a bag filtration step.
=
Preferably, at water flow rates lower than I 000m3/day1 the fluid degassing
step is performed by using a
double loop gas bubbler. More preferably, the double loop gas bubbler
comprises. apertures facing downward
at an angle of 45'.
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Preferably, at water flow rates higher than 1000m3/day, the fluid degassing
step and optional fluid shearing
step is done by a diffuser tower (such as a Sea diffuser).
Preferably, the filtration step, preferably by a method such as a spiral
filter (spiral water filter) and the
multimedia filtration step is performed by using a ceramic media such as
Macrolite or glass beads,
Preferably, the mechanical separation steps are performed through the use of a
cone bottomed tank or any
other mechanical separation equipment such that is equipped with an oil
skimmer at the top of the tank or
overflow or standpipe.
Preferably, the solids removal step through the addition of chemicals such as
coagulant or flocculant.
Preferably. the second oil removal step comprises the use of a single or two
stage polymer packing vessel for
oil adsorption such as Mycelx61).
Preferably, according to the process of the present invention, the treated
polymer flood water for reuse in
polymer flood water has the following specification:
,
, JI'tc r=ri.1-.t1
k:a.'1: Is* , = P. ¨
pH
83 ¨ 10.5
Calcium <20 ppm
Magnesium 100 ¨ 220 ppm
Total Hardness as CaCO3 400 ¨ 800 ppm
TDS 15000 - 25000 ppm
I-12S <50 ppm
02 < 50 pph
Sulphide <60 ppm
Sodium 6000 - 9000 ppm
Total alkalinity 1500 ¨ 2500 ppm
Turbidity <100 NTU
TSS <250 ppm
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IIron I < 1 ppm
Preferably, according to the process of the present invention, the treated
polymer flood water specification
shown above for reuse in polymer flood water can be recycled and retreated
until the TDS reaches the
desired spec target then one can add additional equipment to create the
following SAGD or CSS thermal
water specification for steam flooding:
________________________________________________ .01.=== __
VI'4441:in . r4a = Rn. ; tt*"
=,ta .= t-'1 P-9,r-tr;m-e
'S$14'104(';,CiA,t
pH 8.5 ¨ 10.5
Calcium <0.1 ppm
_ -
Magnesium <0.1 ppm
Total Hardness as CaCO3 <0.5 ppm
TDS <12000 ppm
H2S Oppm
02 < 10 ppb
Sulphide nfa
Sodium <9000 ppm
Total alkalinity <700 ppm
Turbidity <2 NTU
TSS <1 ppm
iron <0.5 ppm
Preferably, according to the process of the present invention, the treated
polymer flood water for reuse in
alkaline surfactant polymer (ASP) or alkaline surfactant brine polymer (ASBP)
has the following
specification:
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VnItlitIP)[ "kirr,
AliftrA ' C4;4*et
r";,"' ;',#F1001 -õoArizgol, 71. dt'
" 'µ'' A; 4 caleiliti
pH 7.5 ¨ 13.0
Calcium <10 ppm
Magnesium <10 ppm
Total Hardness as CaCO3 30 - 70 ppm
TDS 8000 - 25000 ppm
H2 S PPM
02 < 50 ppb
Sodium <8500 ppm
Total alkalinity <5000 ppm
Turbidity < 0 NTU
TSS <20 ppm
Iron <1 ppm
Preferably, the process further cornprises a step of polymer mixing and aging.
More preferably, the process
further comprises the use of a nitrogen blanket during the step of polymer
mixing and aging. More
preferably, the process comprises a step of addition of water to hydrate the
polymer, said water is selected
From the group consisting of: fresh water, treated saline water, treated
produced water and treated blends of
the waters.
Preferably, the process further comprises a step of tank gas bubbler or inlet
diffusion tower,
eleetrocoagulation, and multimedia filtration or spiral filtration of the
produced water, and fresh water
hydration of the polymer mixing solution.
Preferably, the treated water has the following specification: pH >8.5 and
<10.5 9.0; fi2S <50 ppm and 07, <
50 ppb; TSS (total suspended solids) <250 ppm; and calcium ion <20 ppm.
Preferably, dependent on the water or polymer flood fluid characteristics, the
alkaline surfactant polymer
(ASP) may be converted to an alkaline surfactant brine polymer where brine is
used instead of some of the
alkaline chemical to raise the fluid stream conductivity thus reducing the
chemical costs for the mixture.
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BRIEF DESCRIPTION OF THE FIGURES,
Figure 1 is a schematic representation. of the process 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 the process 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 i.s a schematic representation of the process according to a
preferred embodiment of the present
invention where the produced water is treated to be reused in alkaline
surfactant brine polymer flood water.
DETAILED DESCM1191ST OF TIIEINVINTION
The process according to the present invention is intended for use in treating
various used waters reclaimed
from operations in the oil industry, more.spe,cifically, polymer flood, SAGD
and CSS thermal flood, alkaline
surfactant polymer flood, and alkaline surfactant brine polymer flood waters,
for their subsequent reuse.
PolvraeLFIood Water Treatment
The polymer flood water treatment unit according to an embodiment of the
present invention, may comprise
an inlet mixing/solids tank with a gas bubbler or inlet diffusion tower and
tank; an electroeoagulation unit; a
solids removal/handling system; one or more multimedia filtration units or
spiral filtration units; and one or
more chemical injection systems.
The polymer flood water treatment unit according to another embodiment of the
present invention, may
comprise an inlet mixing/solids tank (with or without a gas bubbler or with or
without an inlet diffusion
tower); an electrocoagulation unit; a solids removal/handling system; one or
more multimedia filtration units
or spiral filtration units; and one or more chemical injection systems.
One advantage of the process according to the present invention is the removal
of the residual recycled
polymer from the produced water stream. Another advantage is that the pH of
the water is adjusted to the
optimal range for each polymer to become viscous. Yet another advantage is the
removal of I-12S 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, ie safer
for operations when there is
no 142S venting from the plant polymer injection equipment. Another advantage
of the process according to
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the present invention entails 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. The use of CDG gels require no bacteria if gels were to be used
in the future instead of
polymers. It is worthy of mention that the process according to the present
invention allows for the removal
of oil and grease residue 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
future SAGD or CSS thermal
water requirements. An advantage according to one aspect of the present
invention is that benign water is
created which, in tum, leads to savings on materials for construction of
pipelines and polymer hydration and
injection facilities. Other advantages include the creation of a stable
polymer created 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.
The H2S and 02 rear:flop consumes polymer very aggressively and we found that
by reducing or removing
the 112S from the fluid this reaction does not occur so rapidly, therefore one
is capable of reducing the
amount of polymer usage with lower 142S 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 in/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
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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 Wafer Pilot
In a pilot trial that was conducted, the five (5) main water streams were
tested in multiple equipment
configurations to achieve electrocoagulation and filtration/chemical treatment
during the pilot were Grand
Rapids, Quaternary, Sour S.aline 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
embodiments according to the present invention averaged 2200 ppm.
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:
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, = , ____ = ,,,th;g=
a;11',
,
...õ%a
g' ,Pf:77j1Z1
1.16:=1 µ; I .11: ,117 PAL= =;µ,11-µ0.
pH 8.5 ¨ 10.5
Calcium <20 ppm
Magnesium 100 ¨ 220 ppm
Total Hardness as CaCO3 400 ¨ 800 ppm
TDS 5000 - 25000 ppm
1-12S <50 ppm
07. < 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:
p1-1 5 9.0 or pH > 10.5, had an impact of about 200- 300 ppm polymer loading
increase
1-12S 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.
From the trial results, it was determined that tank gas bubbler 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/M1VTF
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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 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 I-12S 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 water blended with some fresh
water (with tank gas
bubbler/EC/NEW treated water being used for the blend water and fresh water
being used for polymer
mother solution hydration) resulted in an additional 175 ppm in polymer
savings - from 1050 ppm down to
875 ppm polymer loading
A separate system containing only filtration and chemicals was also tested for
comparison to the tank gas
bubblerielectrocoagulation/multimedia filtration 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 Macrolite6 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.
The process according to the present is described with reference to specific
embodiments illustrated in
Figures 1 ¨3.
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Examnle 1 - Polymer Flood Water Treatment Process
A preferred embodiment of the present invention relates to the treatment of
polymer flood water used in
oilfields. It will be better understood by referring to Figure 1. There is
provided a process where:
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 1-12S and other gases (27) present in the fluid. Natural gas
volume is added at a 1 to 1
ratio to the fluid offgas volume. Alternatively, the resulting fluid (15) may
:flow into an inlet diffuser
tower (such as a Seek diffuser) and subsequently into the tank.
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 (37) are used (like
Mycelt).
4) If the resulting fluid's (35) oil and grease level is sufficient, then the
fluid (35) is pumped and
undergoes a pH adjustment (40Xif 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
Waveionice) 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
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 Macrolite ) in single or double filtration stages removing solids, oil and.
polymer (97).
Alternatively, any one of steps 7, 8, and/or 9 can be performed by using a
spiral filter.
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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) or spiral filter.
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.
If using multimedia filtration units, 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 bacicwaShing 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.
A tank gas bubbler as used in step 2) of the treatment process above (and in
examples 2 and 3) was used in
the inlet tank to degas the gases from the water requiring treatment.
The tank square double loop gas bubbler used in the treatment of polymer flood
water was made of linear
tubing the loops overlapping each other and 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 the optimal removal,
from the waters to be treated, of
H2S present and other gases which have deleterious effects on polymers used in
polymer flood waters.
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The tank gas bubbler used in the treatment of polymer flood waters allows to
effectively remove the H2S
from the grosmont and produced waters which, in turn, improves the polymer
loading for subsequent
polymer flood treatment. This leads to savings in polymer usage to meet
viscosity target.
The tank gas bubbler can be used for any water fluid requiring H2S removal
from system ¨ and it greatly
improves the downstream safety of fluid handling with reduced 112S levels.
Another advantage of the tank
gas bubbler 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 control program.
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.
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 now
rate of the gas being used in the operation.
Exa ,,e ¨ team A -sisted Gravi D ."J = = e A D or C clic S : I01 lati.n
Stea CSS 11,,erma1 Water
from Polymer Flood Water Treatment
If the MS 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;
',F,;',,riAl!;'4,0- ii;r--., ,=L' --7'.77.77:777-77717,.µt j =''''- ''' i ' 4
": q
;);,f
4'õ47:0 vo: I ',7,.t.i i . ' ¶4' 1 =,' ' '-- , , '
1., , õ ,,,,r = - , 44,,,"4õ
4
1,1-1 8.5 ¨ 10.5
Calcium <0.1 ppm
Magnesium <0.1 ppm
Total Hardness as CaCO3 <0-5 ppm
TDS <12000 ppm
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H2S 0 ppm
02 <10 ppb
Sulphide n/a
Sodium <9000 ppm
Total alkalinity <700 ppm
Turbidity <2 NTU
TSS <1 ppm
Iron <0.5 ppm
According to a preferred embodiment of the process of the invention, there is
provided a process to prepare
Steam Assisted Gravity Drainage (SAOD) or Cyclic Steam Stimulation (CSS)
thermal water from polymer
flood water treatment. It will be better understood by referring to Figure 3.
The process comprises the
following steps where:
I) 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 (I-12S 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 I-12S and
other gases (27) present in the fluid. Natural, gas volume is added at a 1 to
1 ratio to the fluid offgas
volume. Alternatively, the resulting fluid (IS) may flow into an inlet
diffuser tower (such as a Seair
diffuser) and. subsequently into the tank.
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 Mycele) ¨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
Waveionice) this prevents gases from being released into the atmosphere during
the step. The
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electrocoagulation step consists of metal plates with electrodes that are
electrified as the fluid passes
through the cell. Th.e 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)(throu.gh
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
Macrolite or glass beads) in single or double filtration stages or through a
spiral filter.
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
DuoPLOI) followed by
absolute 3M 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.
Alkaline Surfactant Polymet(ASP) or 61kaline Surfactant Brine Po1ymet.(ASBFjc
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:
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,
; ,44114Pet4
'4,;?,,,tc,c = 7 = ,
PH 7.5 ¨13.0
Calcium <10 ppm
Magnesium <10 ppm
Total Hardness as CaCO3 30 - 70 ppm
TDS 8000 - 25000 kpm
S PPrn
02 < 50 ppb
Sodium <8500 ppm
Total alkalinity <5000 ppm
Turbidity <10 NW
TSS <0 ppm
Iron < 1 ppm
The site produced water was treated with oil removal system and water
treatment system as listed below in
Example 3.
The goal was to confirm the water specification for alkaline surfrictant
polymer (ASP) or alkaline surfactant
brine polymer (ASBP) flooding activities determined in laboratd,ry and help in
finding a more economical
water treatment process. It is estimated that the use of a proce$ of treating
ASP or ASBP polymer flood
produced water prior to its reuse in for the same purpose can yield reductions
ranging from 200 to 400 ppm
in the polymer usage on large scale projects.
Alkalinqaurfactant Polymer (ASP) or Alkaline Surfactant Brine Polymer (ASBP)
Flood, Water Spec
The alkaline surfactant polymer (ASP) or alkaline swfactant brine polymer
(ASBP) water specification for
polymers for hydration was determined through field pilot scale tsting at a
rate of 450 rriNlay.
According to an embodiment of the present invention, the allailine surfactant
polymer (ASP) or alkaline
surfactant brine polymer (ASBP) flood water treatment unit coMprises: a tank
gas bubbler, a Mycelx oil
water separator; a Mycelx backwash vessel; at least one multimedia filtration
unit (more preferably, in
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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 the process according to the present invention for
the preparation of an alkaline
surfactant polymer (ASP) or alkaline surfactant brine polymer (.ASBP) flood
water include: the removal of
1-12S and other gases like CO z 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 (OWS 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 rnedias; 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 eost 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 polymer flood water according to
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.
Example 3 ¨ Alkaline Surfactant Polymer/ASP) or Alkaline Surfactant Brine
Polvtner (MU) Flood Water
_Treatment
=
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According to another preferred embodiment of the process of the invention,
there is provided a process to
prepare an allcaline surfactant polymer (ASP) or an alkaline surfactant brine
polymer (ASBP) flood water. It
will be better understood by referring to Figure 2.. The process comprises the
following steps where:
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 1 to 1
ratio to the fluid offgas
volume.
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
(like Mycelx4 ) ¨ there is recovery of an oil stream.
4) The fluid (35) is then pumped through multimedia filtration (90Xlike
ceramic media TVIacrolite) in
single or double filtration stages:
a. Oxidant Chemical (91)(like bleach or hydrogen peroxide if the water is
sour) 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);
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 (if necessary)
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 so.lids, 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.
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b. Optionally, it has an additional alkaline chemical injection step
(like caustic) as part of the
regeneration cycle ¨ the alkaline chemicals arc being utilized to remove
polymer, silica, and
oil from the strong acid cation resin beads.
7) Tn 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 DuoFLO6 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).
