U.S. patent number 10,385,253 [Application Number 14/799,684] was granted by the patent office on 2019-08-20 for salt tolerant friction reducer.
This patent grant is currently assigned to Solvay USA Inc.. The grantee listed for this patent is Solvay USA Inc.. Invention is credited to Shih-Ruey Tom Chen, Kevin Walter Frederick, Randy Jack Loeffler, Kailas Sawant.
United States Patent |
10,385,253 |
Frederick , et al. |
August 20, 2019 |
Salt tolerant friction reducer
Abstract
A friction reducing treatment solution that includes water, from
100 to 500,000 ppm of total dissolved solids, and from 0.5 to 3
gallons per thousand gallons of a water-in-oil emulsion containing
a water soluble polymer. The total dissolved solids include at
least 10 weight percent of a multivalent cation. The water-in-oil
emulsion includes an oil phase and an aqueous phase, where the oil
phase is a continuous phase containing an inert hydrophobic liquid
and the aqueous phase is present as dispersed distinct particles in
the oil phase and contains water, the water soluble polymer, and
surfactants and an inverting surfactant. The water soluble polymer
is made up of 20 to 80 weight percent of a non-ionic monomer, 0.5
to 30 weight percent of a carboxylic acid containing monomer, and 5
to 70 weight percent of a cationic monomer and makes up from 10 to
35 weight percent of the water-in-oil emulsion.
Inventors: |
Frederick; Kevin Walter (Evans
City, PA), Chen; Shih-Ruey Tom (Pittsburgh, PA),
Loeffler; Randy Jack (Carnegie, PA), Sawant; Kailas
(Castanea, PA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Solvay USA Inc. |
Cranbury |
NJ |
US |
|
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Assignee: |
Solvay USA Inc. (Princeton,
NJ)
|
Family
ID: |
55074033 |
Appl.
No.: |
14/799,684 |
Filed: |
July 15, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160017203 A1 |
Jan 21, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62024652 |
Jul 15, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K
8/64 (20130101); C09K 8/82 (20130101); C09K
8/36 (20130101); C09K 2208/28 (20130101) |
Current International
Class: |
C09K
8/36 (20060101); C09K 8/82 (20060101); E21B
43/26 (20060101); C09K 8/64 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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81/01007 |
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Apr 1981 |
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WO |
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0106999 |
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Feb 2001 |
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WO |
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Other References
Aften, C.W., et al., "Improved friction reducer for hydraulic
fracturing". Hydraulic Fracturing Technology Conference, Society of
Petroleum engineers, 2009, SPE 118747. See abstract: Statement of
Theory and Definitions, fourth paragraph; Description of
Methodology; Surfactants; and Friction Loop Testing. cited by
applicant .
Ferguson, Marcelle L., et al., "Innovative friction reducer
provides improved performance and greater flexibility in recycling
highly mineralized produced brines", Unconventional Resources
Conference--USA, Society of Petroleum Engineers, 2013, SPE 164535.
See abstract: and Development of DPFR. cited by applicant.
|
Primary Examiner: Figueroa; John J
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. provisional patent
application No. 62/024,652 filed Jul. 15, 2014, the contents of
which are incorporated herein by reference in their entirety.
Claims
We claim:
1. A friction reducing treatment solution comprising: water; from
100 to 500,000 ppm of total dissolved solids, wherein the total
dissolved solids comprise at least 10 weight percent of a
multivalent cation; from 0.5 to 3 gallons per thousand gallons of a
water-in-oil emulsion comprising an oil phase (O) and an aqueous
phase (A) at an O/A ratio of from about 1:8 to about 10:1, wherein
the oil phase is a continuous phase comprising an inert hydrophobic
liquid; wherein the aqueous phase is present as dispersed distinct
particles in the oil phase and comprises water, a water soluble
polymer, and surfactants; wherein the water soluble polymer
comprises 20 to 80 weight percent of a non-ionic monomer, 0.5 to 30
weight percent of a carboxylic acid containing monomer, and 5 to 70
weight percent of a cationic monomer; and wherein the water soluble
polymer comprises from 5 to 40 weight percent of the water-in-oil
emulsion; and an inverting surfactant.
2. The friction reducing treatment solution according to claim 1,
wherein the cationic monomer is one or more selected from the group
consisting of (meth)acrylamidopropyltrimethyl ammonium halides,
(meth)acryloyloxyethyltrimethyl ammonium halides,
(meth)acryloyloxyethyltrimethyl ammonium methyl sulfate, diallyl
dimethyl ammonium halides, diallylamine, methyldiallylamine,
dimethylaminoethylmethacrylate, and
dimethylaminopropylmethacrylamide.
3. The friction reducing treatment solution according to claim 1,
wherein the nonionic monomer is one or more selected from the group
consisting of C.sub.1-C.sub.3 alkyl (meth)acrylates,
C.sub.1-C.sub.3 N-alkyl (meth)acrylamide, (meth)acrylamide,
N-vinylpyrrolidone, dimethyl(meth)acrylamide, N-vinyl acetamide,
and N-vinyl formamide.
4. The friction reducing treatment solution according to claim 1,
wherein the carboxylic acid containing monomer is one or more
carboxylic acid containing monomers selected from the group
consisting of (meth)acrylic acid, maleic acid, itaconic acid,
N-(meth)acrylamidopropyl, N,N-dimethyl,amino acetic acid,
N-(meth)acryloyloxyethyl, N,N-dimethyl,amino acetic acid,
N-(meth)acryloyloxyethyl, N,N-dimethyl,amino acetic acid, crotonic
acid, (meth)acrylamidoglycolic acid, and
2-(meth)acrylamido-2-methylbutanoic acid.
5. The friction reducing treatment solution according to claim 1,
wherein the multivalent cation is one or more selected from the
group consisting of iron, calcium, magnesium, manganese, strontium,
barium, and zinc.
6. The friction reducing treatment solution according to claim 1,
wherein the water soluble polymer has a molecular weight in the
range of from about 2,000,000 to about 30,000,000.
7. The friction reducing treatment solution according to claim 1,
wherein the water soluble polymer has a reduced viscosity, as
determined in a Ubbelhhde Capillary Viscometer at 0.05% by weight
concentration of the polymer in 1M NaCl solution, at 30.degree. C.,
pH 7, of from about 10 to about 40 dl/g.
8. The friction reducing treatment solution according to claim 1,
wherein the water-in-oil emulsion comprises at least one of an
inhibitor or a salt.
9. The friction reducing treatment solution according to claim 1,
wherein the water-in-oil emulsion comprises ammonium salt,
4-methoxyphenol, and an ethoxylated C.sub.12-C.sub.16 alcohol.
10. The friction reducing treatment solution according to claim 1,
wherein the inert hydrophobic liquid comprises a mixture of
paraffinic hydrocarbons and napthenic hydrocarbons.
11. The friction reducing treatment solution according to claim 1,
wherein the surfactants comprise a tall oil fatty acid diethanol
amine, a polyoxyethylene (5) sorbitan monooleate, and a sorbitan
monooleate.
12. The friction reducing treatment solution according to claim 1,
wherein the molar ratio of cationic monomer to anionic monomer is
at least 1.5:1.
13. The friction reducing treatment solution according to claim 1,
wherein the molar ratio of cationic monomer to anionic monomer is
up to 1:1.5.
14. A friction reducing treatment solution comprising: water; from
100 to 50,000 ppm of total dissolved solids, wherein the total
dissolved solids comprise at least 10 weight percent of a
multivalent cation; from 0.5 to 3 gallons per thousand gallons of a
water-in-oil emulsion comprising an oil phase (O) and an aqueous
phase (A) at an O/A ratio of from about 1:8 to about 10:1, wherein
the oil phase is a continuous phase comprising an inert hydrophobic
liquid; wherein the aqueous phase is present as dispersed distinct
particles in the oil phase and comprises water, a water soluble
polymer, and surfactants; wherein the water soluble polymer
comprises 20 to 80 weight percent of a non-ionic monomer, 0.5 to 30
weight percent of a carboxylic acid containing monomer, and 5 to 70
weight percent of a cationic monomer; and wherein the water soluble
polymer comprises from 10 to 35 weight percent of the water-in-oil
emulsion; and an inverting surfactant.
Description
BACKGROUND
The disclosed subject matter relates to compositions for treating
subterranean zones. The compositions include aqueous subterranean
treatment fluids that contain water soluble polymers in a
water-in-oil emulsion in high brine containing solutions and
associated methods.
Aqueous treatment fluids may be used in a variety of subterranean
treatments. Such treatments include, but are not limited to,
drilling operations, stimulation operations, and completion
operations. As used herein, the term "treatment," or "treating,"
refers to any subterranean operation that uses a fluid in
conjunction with a desired function and/or for a desired purpose.
The term "treatment," or "treating," does not imply any particular
action by the fluid.
Viscous gelled fracturing fluids are commonly utilized in the
hydraulic fracturing of subterranean zones penetrated by well bores
to increase the production of hydrocarbons from the subterranean
zones. That is, a viscous fracturing fluid is pumped through the
well bore into a subterranean zone to be stimulated at a rate and
pressure such that fractures are formed and extended into the
subterranean zone. The fracturing fluid also carries particulate
proppant material, e.g., graded sand, into the formed fractures.
The proppant material is suspended in the viscous fracturing fluid
so that the proppant material is deposited in the fractures when
the viscous fracturing fluid is broken and recovered. The proppant
material functions to prevent the fractures from closing whereby
conductive channels are formed through which produced fluids can
flow to the well bore.
An example of a stimulation operation utilizing an aqueous
treatment fluid is hydraulic fracturing. In some instances, a
fracturing treatment involves pumping a proppant-free, aqueous
treatment fluid (known as a pad fluid) into a subterranean
formation faster than the fluid can escape into the formation so
that the pressure in the formation rises and the formation breaks,
creating or enhancing one or more fractures. Enhancing a fracture
includes enlarging a pre-existing fracture in the formation. Once
the fracture is formed or enhanced, proppant particulates are
generally placed into the fracture to form a proppant pack that may
prevent the fracture from closing when the hydraulic pressure is
released, forming conductive channels through which fluids may flow
to the well bore.
During the pumping of the aqueous treatment fluid into the well
bore, a considerable amount of energy may be lost due to friction
between the aqueous treatment fluid in turbulent flow and the
formation and/or tubular goods (e.g., pipes, coiled tubing, etc.)
disposed within the well bore. As a result of these energy losses,
additional horsepower may be necessary to achieve the desired
treatment. To reduce these energy losses, friction reducing
polymers have heretofore been included in aqueous treatment fluids.
The friction reducing polymer should reduce the frictional losses
due to friction between the aqueous treatment fluid in turbulent
flow and the tubular goods and/or the formation.
Many friction reducing polymers show a reduced performance in the
presence of low molecular weight additives, such as acids, bases,
and salts. Ionically-charged polymers are particularly susceptible.
For example, polymers containing acrylate-type monomers, either
added as a copolymer or hydrolyzed from polyacrylamide, have a
reduced compatibility with high calcium brines. The additives
screen the charges on the polymer backbone which decreases the
hydrodynamic radius of the polymer. With the decrease in effective
polymer length, the friction reduction also decreases.
Hydraulic fracturing has been a boon to the oil and gas industry.
Many oil and gas wells have been made more productive due to the
procedure. However, the hydraulic fracturing business is now facing
increasing scrutiny and government regulation. In addition, large
volumes of water are required for hydraulic fracturing operations.
Fresh water may be a limiting factor in some areas. A treatment
solution that can use a variety of water sources, such as produced
water from the formation or flowback water after a well treatment,
could significantly enhance the field applicability.
The relatively high polymer usage in subterranean treatment methods
can result in significant formation damage. Further, when the
treatment fluid is recycled above ground, the high levels of high
molecular weight polymers in the fluid can lead to flocculation in
above ground fluid recycle operations such as terminal upsets.
There is an ongoing need to develop treatment solutions that have
effective friction reduction to minimize energy loss but yet have
sufficient viscosity for proppant-carrying capacity, especially in
high brine situations, while being safe and environmentally
friendly.
SUMMARY
The present disclosure provides a friction reducing treatment
solution that includes water, from 100, in many cases from 10,000
to 300,000, in some cases up to about 500,000 ppm of total
dissolved solids, and from 0.5 to 3 gallons per thousand gallons of
a water-in-oil emulsion containing a water soluble polymer. The
total dissolved solids include at least 10 weight percent of a
multivalent cation. The water-in-oil emulsion includes an oil phase
(O) and an aqueous phase (A) at an O/A ratio of from about 1:8 to
about 10:1, where the oil phase is a continuous phase containing an
inert hydrophobic liquid and the aqueous phase is present as
dispersed distinct particles in the oil phase and contains water,
the water soluble polymer, and surfactants and an inverting
surfactant. The water soluble polymer is made up of 20 to 80 weight
percent of a non-ionic monomer, 0.5 to 35 weight percent of a
carboxylic acid containing monomer, and 5 to 70 weight percent of a
cationic monomer. The water soluble polymer comprises from 5 to 40
weight percent of the water-in-oil emulsion.
The present disclosure also provides a method of treating at least
a portion of a subterranean formation that includes introducing the
friction reducing treatment solution into the portion of the
subterranean formation.
DETAILED DESCRIPTION
Other than in the operating examples, or where otherwise indicated,
all numbers or expressions referring to quantities of ingredients,
reaction conditions, etc. used in the specification and claims are
to be understood as modified in all instances by the term "about."
Accordingly, unless indicated to the contrary, the numerical
parameters set forth in the following specification and attached
claims are approximations that may vary depending upon the desired
properties sought to be obtained by the present disclosure. At the
very least, and not as an attempt to limit the application of the
doctrine of equivalents to the scope of the claims, each numerical
parameter should at least be construed in light of the number of
reported significant digits and by applying ordinary rounding
techniques.
Notwithstanding that the numerical ranges and parameters setting
forth the broad scope of the disclosure are approximations, the
numerical values set forth in the specific examples are reported as
precisely as possible. Any numerical values, however, inherently
contain certain errors necessarily resulting from the standard
deviation found in their respective testing measurements.
Also, it should be understood that any numerical range recited
herein is intended to include all sub-ranges subsumed therein. For
example, a range of "1 to 10" is intended to include all sub-ranges
between and including the recited minimum value of 1 and the
recited maximum value of 10; that is, having a minimum value equal
to or greater than 1 and a maximum value of equal to or less than
10. Because the disclosed numerical ranges are continuous, they
include every value between the minimum and maximum values. Unless
expressly indicated otherwise, the various numerical ranges
specified in this application are approximations.
As used herein, the terms "(meth)acrylic" and "(meth)acrylate" are
meant to include both acrylic and methacrylic acid derivatives,
such as the corresponding alkyl esters often referred to as
acrylates and (meth)acrylates, which the term "(meth)acrylate" is
meant to encompass.
As used herein, the term "polymer" is meant to encompass oligomer,
and includes, without limitation, both homopolymers and
copolymers.
As used herein, the term "copolymer," as used herein, is not
limited to polymers containing two types of monomeric units, but
includes any combination of polymers, e.g., terpolymers,
tetrapolymers, and the like.
As used herein, the term "flowback water" refers to fluids that
flow back to the surface after treatment fluids are injected down
hole.
As used herein, "total dissolved solids" ("TDS") refers to a
measure of the combined content of all inorganic and organic
substances contained in water including ionized solids in the
water.
As used herein, the term "brine" refers to water containing
dissolved salt and at least 10,000 ppm TDS. In an embodiment, the
term "brine" refers to water containing dissolved salt and greater
than 30,000 ppm TDS.
The present disclosure provides a friction reducing treatment
solution that includes water, from 100, in many cases from 10,000
to 300,000, in some cases up to about 500,000 ppm of total
dissolved solids, and from 0.5 to 3 gallons per thousand gallons of
a water-in-oil emulsion containing a water soluble polymer. The
total dissolved solids include at least 10 weight percent of a
multivalent cation. The water-in-oil emulsion includes an oil phase
(O) and an aqueous phase (A) at an O/A ratio of from about 1:8 to
about 10:1, where the oil phase is a continuous phase containing an
inert hydrophobic liquid and the aqueous phase is present as
dispersed distinct particles in the oil phase and contains water,
the water soluble polymer, and surfactants and an inverting
surfactant. The water soluble polymer is made up of 20 to 80 weight
percent of a non-ionic monomer, 0.5 to 35 weight percent of a
carboxylic acid containing monomer, and 5 to 70 weight percent of a
cationic monomer. The water soluble polymer comprises from 5 to 40
weight percent of the water-in-oil emulsion.
The present disclosure provides a method of treating a portion of a
subterranean formation that includes introducing the friction
reducing treatment solution into the portion of the subterranean
formation.
The aqueous friction reducing treatment solutions of the present
disclosure generally include water, and a friction reducing
copolymer.
The water-in-oil emulsion includes an oil phase, an aqueous phase
and surfactants. The oil phase (O) and the aqueous phase (A) can be
present at an O/A ratio, based on the volume of each phase of from
at least about 1:8, in some cases at least about 1:6 and in other
cases at least about 1:4 and can be up to about 10:1, in some cases
up to about 8:1 and in other cases up to about 6:1. When the O/A
ratio is too oil heavy, the polymer may be too concentrated in the
aqueous phase. When the O/A ratio is too water heavy, the emulsion
may become unstable and prone to separate. The O/A ratio can be any
ratio or range between any of the ratios recited above.
In the present water-in-oil emulsion, the oil phase is present as a
continuous phase and includes an inert hydrophobic liquid. The
inert hydrophobic liquid can include, as non-limiting examples,
paraffinic hydrocarbons, napthenic hydrocarbons, aromatic
hydrocarbons, benzene, xylene, toluene, mineral oils, kerosenes,
naphthas, petrolatums, branch-chain isoparaffinic solvents,
branch-chain hydrocarbons, saturated, linear, and/or branched
paraffin hydrocarbons and combinations thereof. Particular
non-limiting examples include natural, modified or synthetic oils
such as the branch-chain isoparaffinic solvent available as
ISOPAR.RTM. M and EXXATE.RTM. available from ExxonMobil
Corporation, Irving Tex., a narrow fraction of a branch-chain
hydrocarbon available as KENSOL.RTM. 61 from Witco Chemical
Company, New York, N.Y., mineral oil, available commercially as
BLANDOL.RTM. from Witco, CALUMET.TM. LVP-100 available from Calumet
Specialty Products, Burnham, Ill., DRAKEOL.RTM. from Penreco
Partnership, Houston, Tex., MAGIESOL.RTM. from Magie Bros., Oil
City, Pa. and vegetable oils such as canola oil, coconut oil,
rapeseed oil and the like.
The inert hydrophobic liquid is present in the water-in-oil
emulsion in an amount sufficient to form a stable emulsion. In some
embodiments, the inert hydrophobic liquid can be present in the
water-in-oil emulsions in an amount in the range of from about 15%
to about 80% by weight.
In embodiments of the disclosure, the inert hydrophobic liquid is
present in the water-in-oil emulsion at a level of at least about
15, in some cases at least about 17.5, in other cases at least
about 20, and in some instances at least about 22.5 weight percent
based on the weight of the water-in-oil emulsion and can be present
at up to about 40, in some cases up to about 35, in other cases up
to about 32.5 and in some instances up to about 30 weight percent
based on the weight of the water-in-oil emulsion. The total amount
of inert hydrophobic liquid in the water-in-oil emulsion can be any
value or can range between any of the values recited above.
Any suitable water-in-oil emulsifier can be used as the one or more
surfactants used to make the water soluble polymer containing
water-in-oil emulsion used in the present method. In embodiments of
the disclosure, the surfactants include those having an HLB
(hydrophilic-lipophilic balance) value between 2 and 10 in some
cases between 3 and 9 and in other cases between 3 and 7.
As used herein, HLB is calculated using the art known method of
calculating a value based on the chemical groups of the molecule.
The method uses the following equation: HLB=7+m*Hh+n*Hl where m
represents the number of hydrophilic groups in the molecule, Hh
represents the value of the hydrophilic groups, n represents the
number of lipophilic groups in the molecule and Hl represents the
value of the lipophilic groups.
Non-limiting examples of suitable surfactants include: fatty acid
esters of mono-, di- and polyglycerols, for instance the monoleate,
the dioleate, the monostearate, the distearate and the
palmitostearate. These esters can be prepared, for example, by
esterifying mono-, di- and polyglycerols, or mixtures of
polyhydroxylated alcohols such as ethylene glycol, diethylene
glycol, dipropylene glycol, 1,4-butanediol, 1,2,4-butanetriol,
glycerol, trimethylolpropane, sorbitol, neopentyl glycol and
pentaerythritol; fatty acid esters of sorbitan, for instance
sorbitan monoleate, sorbitan dioleate, sorbitan trioleate, sorbitan
monostearate and sorbitan tristearate; fatty acid esters of
mannitol, for instance mannitol monolaurate or mannitol
monopalmitate; fatty acid esters of pentaerythritol, for instance
pentaerythritol monomyristate, pentaerythritol monopalmitate and
pentaerythritol dipalmitate; fatty acid esters of polyethylene
glycol sorbitan, more particularly the monooleates; fatty acid
esters of polyethylene glycol mannitol, more particularly the
monooleates and trioleates; fatty acid esters of glucose, for
instance glucose monooleate and glucose monostearate;
trimethylolpropane distearate; the products of reaction of
isopropylamide with oleic acid; fatty acid esters of glycerol
sorbitan; ethoxylated alkylaines; sodium hexadecyl phthalate;
sodium decyl phthalate; and oil-soluble alkanolamides.
In particular embodiments of the disclosure, the surfactants can
include ethoxylated nonionic surfactants, guerbet alcohol
ethoxylate, and mixtures thereof. Specific examples include, but
are not limited to tall oil fatty acid diethanolamine, such as
those available as AMADOL.RTM. 511, from Akzo Nobel Surface
Chemistry, Chicago, Ill.; polyoxyethylene (5) sorbitan monoleate,
available as TWEEN.RTM. 81, from Uniqema, New Castle, Del.;
sorbinate monoleate, available as SPAN.RTM. 80 from Uniquena, and
ALKAMULS.RTM. SMO, from Rhone Poulenc, Inc., Paris, France.
The surfactants can be present at a level of at least about 0.1, in
some instances at least about 0.25, in other instances at least
about 0.5, in some cases at least about 0.75 and in other cases at
least about 1 weight percent of the water-in-oil emulsion. When the
amount of surfactants is too low, the aqueous phase may not be
adequately dispersed in the oil phase and/or the water-in-oil
emulsion may tend to separate into oil and aqueous phases. Also,
the amount of surfactants can be up to about 7, in some cases up to
about 5, and in other cases up to about 2.5 weight percent of the
water-in-oil emulsion. The amount of surfactants in the
water-in-oil emulsion can be any value or can range between any of
the values recited above.
The aqueous phase is a dispersed phase of distinct particles in the
oil phase and includes water and a water soluble polymer. The
aqueous phase in total can be present in the present water-in-oil
emulsion polymer composition at a level of at least about 60, in
some instances at least about 65, in some cases at least about
67.5, and in other cases at least about 70 weight percent based on
the weight of the water-in-oil emulsion and can be present at up to
about 85, in some cases up to about 82.5, in other cases up to
about 80 and in some instances up to about 77.5 weight percent
based on the weight of the water-in-oil emulsion. The total amount
of aqueous phase in the water-in-oil emulsion can be any value or
can range between any of the values recited above.
In the present disclosure, the water soluble polymer is present at
a level of at least about 5, in some instances 10, in some cases at
least about 15, and in other cases at least about 20 weight percent
based on the weight of the water-in-oil emulsion and can be present
at up to about 33, in some cases up to about 35, in other cases up
to about 37 and in some instances up to about 40 weight percent
based on the weight of the water-in-oil emulsion. When the amount
of water soluble polymer is too low, the use of the water-in-oil
emulsion in the present method of treating a portion of a
subterranean formation may be uneconomical. When the amount of
water soluble polymer is too high, the performance of the water
soluble polymer in the present method of treating a portion of a
subterranean formation may be less than optimal. The amount of
water soluble polymer in the aqueous phase of the water-in-oil
emulsion can be any value or can range between any of the values
recited above.
The water soluble polymer in the water-in-oil emulsion is prepared
by polymerizing a monomer solution that includes non-ionic
monomers, cationic monomers, and carboxylic acid containing
monomers included at a level that provides the desired amount of
water soluble polymer.
The amount of non-ionic monomer can be at least about 20, in some
cases at least about 33, and in other cases at least about 35
weight percent based on the weight of the monomer mixture. When the
amount of non-ionic monomer is too low, the molecular weight of the
resulting water soluble polymer may be lower than desired. Also,
the amount of non-ionic monomer in the monomer mixture can be up to
about 80, in some case up to about 57.5, and in other cases up to
about 55 weight percent based on the weight of the monomer mixture.
When the amount of non-ionic monomer is too high, the water soluble
polymer may not carry enough ionic charge to optimally function as
a friction reducing polymer. The amount of non-ionic monomer in the
monomer mixture can be any value or range between any of the values
recited above.
The monomer mixture typically includes (meth)acrylamide as a
non-ionic monomer.
The water soluble polymer can include other non-ionic monomers to
provide desirable properties to the polymer. Non-limiting examples
of suitable other non-ionic monomers that can be included in the
monomer mixture, and ultimately the resulting water soluble polymer
include N,N-dimethyl(meth)acrylamide (DMF), N-vinyl acetamide,
N-vinyl formamide, acrylonitrile (including hydrolyzed products of
acrylonitrile residues), acrylonitrile-dimethyl amine reaction
products, and and/or corresponding salts, non-limiting examples
being sodium, potassium and/or ammonium and mixtures thereof.
The monomer mixture includes a carboxylic acid containing monomer
or its corresponding salts, non-limiting examples being sodium,
potassium and ammonium. Particular useful examples of carboxylic
acid containing monomers include, but are not limited to
(meth)acrylic acid, maleic acid, itaconic acid,
N-(meth)acrylamidopropyl, N,N-dimethyl,amino acetic acid,
N-(meth)acryloyloxyethyl, N,N-dimethyl,amino acetic acid,
N-(meth)acryloyloxyethyl, N,N-dimethyl,amino acetic acid, crotonic
acid, (meth)acrylamidoglycolic acid, and
2-(meth)acrylamido-2-methylbutanoic acid. The amount of carboxylic
acid containing monomer can be at least about 0.5, in some cases at
least about 1, and in other cases at least about 2 weight percent
based on the weight of the monomer mixture. When the amount of
carboxylic acid containing monomer is too low, the water soluble
polymer may not carry enough anionic charge to optimally function
as a friction reducing polymer in high brine solutions. Also, the
amount of carboxylic acid containing monomer in the monomer mixture
can be up to about 35, in some case up to about 20, and in other
cases up to about 15 weight percent based on the weight of the
monomer mixture. When the amount of carboxylic acid containing
monomer is too high, the water soluble polymer may have undesirable
flocculation properties when used in the present method. The amount
of carboxylic acid containing monomer in the monomer mixture can be
any value or range between any of the values recited above. The
carboxylic acid containing monomers can also be referred to as
anionic monomers.
In some embodiments of the present disclosure, the monomer mixture
and/or water soluble polymer does not include (meth)acrylic
acid.
The monomer mixture typically includes a cationic monomer or its
corresponding salts, non-limiting examples being chloride and
methylsulfate. Particular useful examples of such cationic monomers
include, but are not limited to (meth)acrylamidopropyltrimethyl
ammonium halides, (meth)acryloyloxyethyltrimethyl ammonium halides,
N,N-Dimethylaminoethyl(meth)acrylate,
(meth)acryloyloxyethyltrimethyl ammonium methyl sulfate, and
diallyl dimethyl ammonium halides.
In some embodiments of the disclosure, the cationic monomer can be
a monomer that contains an amine group ("amine containing monomer")
that takes on a positive charge at pH levels less than 7, in some
cases less than 6 and in other cases less than 5. Non-limiting
examples of amine containing monomers that can be used as cationic
monomers in the present disclosure include diallylamine (DAA),
methyldiallylamine (MDAA), dimethylaminoethylmethacrylate (DMAEM),
and dimethylaminopropylmethacrylamide (DMAPMA).
The amount of cationic monomer can be at least about 5, in some
cases at least about 15, and in other cases at least about 20
weight percent based on the weight of the monomer mixture. When the
amount of cationic monomer is too low, the water soluble polymer
may not carry enough cationic charge to optimally function as a
friction reducing polymer in high brine solutions. Also, the amount
of cationic monomer in the monomer mixture can be up to about 70,
in some case up to about 50, in other cases up to about 40, in some
instances up to about 30, and in other instances up to about 25
weight percent based on the weight of the monomer mixture. When the
amount of cationic monomer is too high, the water soluble polymer
may have undesirable flocculation properties when used in the
present method. The amount of cationic monomer in the monomer
mixture can be any value or range between any of the values recited
above.
Typically, the composition of the water soluble polymer will be the
same or about the same as the composition of the monomer
mixture.
Not being limited to any single theory, it is believed that the
water soluble polymers of the present disclosure do not decrease
their hydrodynamic volume due to the presence of ions in the
treatment solution as is the case with prior art water soluble
polymers. Because the present water soluble polymers contain
anionic groups from the anionic monomers and cationic groups from
the cationic monomers, they tend to have a somewhat smaller
hydrodynamic volume when no salt ions are present in the treatment
fluid. When salt ions are present, they tend to associate with the
anionic and cationic groups in the present water soluble polymers
causing the hydrodynamic volume of the present water soluble
polymers to become larger, which results in more viscosity build
and more of a friction reducing effect.
In one embodiment of the present disclosure, the viscosity build
and friction reducing effect is increased when the molar ratio of
cationic monomer to anionic monomer is at least 1.5:1, in some
cases at least 1.75:1 and in other cases at least 2:1.
In other embodiments of the present disclosure, the viscosity build
and friction reducing effect is increased when the molar ratio of
cationic monomer to anionic monomer is not more than 1:1.5, in some
cases not more than 1:1.75 and in other cases not more than
1:2.
The water-in-oil emulsion of the present disclosure can be made
down into a 2 wt % aqueous solution of the inverted water-in-oil
emulsion. The bulk viscosity of the solution can be measured at
25.degree. C. using a Brookfield RV instrument equipped with an
appropriate spindle at 10 rpm at 25.degree. C. (Brookfield
Engineering Laboratories, Inc., Middleboro, Mass.).
Thus, the water soluble polymers in the dispersed aqueous phase
particles of the present water-in-oil emulsion are able to provide
a greater friction reducing effect by reducing the energy losses
due to friction in brine containing aqueous treatment fluids of the
present disclosure. As a non-limiting example, the water soluble
polymers of the present disclosure can reduce energy losses during
introduction of the aqueous treatment fluid into a well bore due to
friction between the aqueous treatment fluid in turbulent flow and
the formation and/or tubular good(s) (e.g., a pipe, coiled tubing,
etc.) disposed in the well bore.
The water-in-oil emulsion containing the water soluble polymer of
the present method is prepared using water-in-oil emulsion
polymerization techniques. Suitable methods to effect such
polymerizations are known in the art, non-limiting examples of such
being disclosed in U.S. Pat. Nos. 3,284,393; 4,024,097; 4,059,552;
4,419,344; 4,713,431; 4,772,659; 4,672,090; 5,292,800; and
6,825,301, the relevant disclosures of which are incorporated
herein by reference.
Typically, the water-in-oil polymerization is carried out by mixing
the surfactants with the oil phase, which contains the inert
hydrophobic liquid. The aqueous phase is then prepared combining a
monomer mixture with water in the desired concentration.
Additionally, a chelant, such as a sodium salt of EDTA can
optionally be added to the aqueous phase and the pH of the aqueous
phase can be adjusted to 3.0 to 10.0, depending on the particular
monomer(s) in the monomer mixture. The aqueous phase is then added
to the mixture of oil phase and surfactants. The surfactants enable
the aqueous phase, which contains the monomer mixture, to be
emulsified into and form discrete particles in the oil phase.
Polymerization is then carried out in the presence of a free
radical generating initiator.
Any suitable initiator can be used. Non-limiting examples of
suitable initiators include diethyl 2,2'-azobisisobutyrate,
dimethyl 2,2'-azobisisobutyrate, 2-methyl 2'-ethyl
azobisisobutyrate, benzoyl peroxide, lauroyl peroxide, sodium
persulfate, potassium persulfate, tert-butyl hydroperoxide,
dimethane sulfonyl peroxide, ammonium persulfate,
azobisisobutylronitrile, dimethyl 2,2'-azobis(isobutyrate) and
combinations thereof.
The amount of initiator can be from about 0.01 to 1% by weight of
the monomer mixture, in some cases from 0.02% to 0.5% by weight of
the monomer mixture.
In some embodiments of the disclosed subject matter, the
polymerization technique may have an initiation temperature of
about 25.degree. C. and proceed approximately adiabatically. In
other embodiments of the disclosure, the polymerization can be
carried out isothermally at a temperature of about from 37.degree.
C. to about 50.degree. C.
In some embodiments, the oil-in-water emulsion can include a salt.
Among other things, the salt can be present to add stability to the
emulsion and/or reduced viscosity of the emulsion. Examples of
suitable salts, include, but are not limited to, ammonium chloride,
potassium chloride, sodium chloride, ammonium sulfate, and mixtures
thereof. In some embodiments, the salt can be present in emulsions
in an amount in the range of from about 0.5% to about 2.5% by
weight of the emulsion.
In some embodiments, the oil-in-water emulsions can include an
inhibitor. Among other things, the inhibitor can be included to
prevent premature polymerization of the monomers prior to
initiation of the emulsion polymerization reaction. As those of
ordinary skill in the art will appreciate, with the benefit of this
disclosure, the water soluble polymer may have been synthesized
using an emulsion polymerization technique wherein the inhibitor
acted to prevent premature polymerization. Examples of suitable
inhibitors include, but are not limited to, quinones. An example of
a suitable inhibitor comprises a 4-methoxyphenol (MEHQ). The
inhibitor should be present in an amount sufficient to provide the
desired prevention of premature polymerization. In some
embodiments, the inhibitor may be present in an amount in the range
of from about 0.001% to about 0.1% by weight of the emulsion.
The water soluble polymers of the disclosed subject matter
typically have a molecular weight sufficient to provide a desired
level of friction reduction. Generally, friction reducing polymers
have a higher molecular weight in order to provide a desirable
level of friction reduction. As a non-limiting example, the weight
average molecular weight of the friction reducing copolymers may be
in the range of from about 2,000,000 to about 20,000,000, in some
cases up to about 30,000,000, as determined using intrinsic
viscosities. Those of ordinary skill in the art will recognize that
friction reducing copolymers having molecular weights outside the
listed range may still provide some degree of friction reduction in
an aqueous treatment fluid.
As used herein, intrinsic viscosity is determined using a Ubbelhhde
Capillary Viscometer and solutions of the water soluble polymer in
1M NaCl solution, at 30.degree. C., and pH 7 at 0.05 wt. %, 0.025
wt. % and 0.01 wt. % and extrapolating the measured values to zero
concentration to determine the intrinsic viscosity. The molecular
weight of the water soluble polymer is then determined using the
Mark-Houwink equation as is known in the art.
Alternatively, the reduced viscosity of the water soluble polymer
at 0.05 wt. % concentration is used to measure molecular size. As
such, the water soluble polymer has a reduced viscosity, as
determined in a Ubbelhhde Capillary Viscometer at 0.05% by weight
concentration of the polymer in 1M NaCl solution, at 30.degree. C.,
pH 7, of from about 10 to about 40 dl/g, in some cases from 15 to
about 35 dl/g, and in other cases 15 to about 30 dl/g.
Suitable water soluble polymers of the disclosure can be in an acid
form or in a salt form. A variety of salts can be made by
neutralizing the carboxylic acid containing monomer with a base,
such as sodium hydroxide, potassium hydroxide, ammonium hydroxide
or the like. As used herein, the term "water soluble polymer" is
intended to include both the acid form of the friction reducing
copolymer and its various salts.
The water-in-oil emulsion is added to water by inverting the
emulsion to form a friction reducing treatment solution. As used
herein, the terms "invert" and/or "inverting" refer to exposing the
water-in-oil emulsion to conditions that cause the aqueous phase to
become the continuous phase. This inversion releases the water
soluble polymer into the make up water.
Methods of inverting water soluble polymer containing water-in-oil
emulsions are known in the art and are disclosed, as a non-limiting
example in U.S. Pat. No. 3,624,019 which is incorporated herein by
reference.
In embodiments of the disclosed subject matter, in order to aid the
inversion, make down and dissolution of the water soluble polymer,
an inverting surfactant can be included in the water-in-oil
emulsion. Among other things, the inverting surfactant can
facilitate the inverting of the emulsion upon addition to make up
water and/or the aqueous treatment fluids of the disclosed subject
matter. As those of ordinary skill in the art will appreciate, with
the benefit of this disclosure, upon addition to the aqueous
treatment fluid, the water-in-oil emulsion should invert, releasing
the copolymer into the aqueous treatment fluid.
Non-limiting examples of suitable inverting surfactants include,
polyoxyethylene alkyl phenol; polyoxyethylene (10 mole) cetyl
ether; polyoxyethylene alkyl-aryl ether; quaternary ammonium
derivatives; potassium oleate; N-cetyl-N-ethyl morpholinium
ethosulfate; sodium lauryl sulfate; condensation products of higher
fatty alcohols with ethylene oxide, such as the reaction product of
oleyl alcohol with 10 ethylene oxide units; condensation products
of alkylphenols and ethylene oxide, such as the reaction products
of isooctylphenol with 12 ethylene oxide units; condensation
products of higher fatty acid amines with five, or more, ethylene
oxide units; ethylene oxide condensation products of polyhydric
alcohol partial higher fatty esters, and their inner anhydrides
(e.g., mannitol anhydride, and sorbitol-anhydride).
In particular embodiments of the disclosed subject matter, the
inverting surfactants can include ethoxylated nonyl phenols,
ethoxylated nonyl phenol formaldehyde resins, ethoxylated alcohols,
nonionic surfactants with an HLB of from 12 to 14, and mixtures
thereof.
A specific non-limiting example of a suitable inverting surfactant
includes an ethoxylated C.sub.12-C.sub.16 alcohol. In some aspects
of the disclosed subject matter, the inverting surfactant can be a
C.sub.12-C.sub.14 alcohol having 5 to 10 units of ethoxylation. The
inverting surfactant can be present in an amount sufficient to
provide the desired inversion of the emulsion upon contact with the
water in the aqueous treatment fluid. In some embodiments, the
inverting surfactant can be present in an amount in the range of
from about 1%, in some cases about 1.1%, in other cases about 1.25%
and can be up to about 5%, in some cases about 4%, in other cases
about 3%, in some instances about 2% and in other instances about
1.75% by weight of the water-in-oil emulsion.
In many embodiments of the disclosed subject matter, the inverting
surfactants are added to the water-in-oil emulsion after the
polymerization is completed.
In some embodiments of the disclosed subject matter, a batch method
can be used to make down the water-in-oil emulsion. In this
embodiment, the water soluble polymer containing water-in-oil
emulsion and water are delivered to a common mixing tank. Once in
the tank, the solution is beat or mixed for a specific length of
time in order to impart energy thereto. After mixing, the resulting
solution must age to allow enough time for the molecules to unwind.
This period of time is significantly reduced in the present
disclosure.
In some embodiments, continuous in-line mixers as well as in-line
static mixers can be used to combine the water soluble polymer
containing water-in-oil emulsion and water. Non-limiting examples
of suitable mixers utilized for mixing and feeding are disclosed in
U.S. Pat. Nos. 4,522,502; 4,642,222; 4,747,691; and 5,470,150,
which are incorporated herein by reference. Non-limiting examples
of suitable static mixers can be found in U.S. Pat. Nos. 4,051,065
and 3,067,987, which are incorporated herein by reference.
Once the water soluble polymer containing water-in-oil emulsion is
made down into water, any other additives are added to the solution
to form a treatment solution, which is then introduced into the
portion of the subterranean formation.
Generally, the water soluble polymer can be included in any aqueous
treatment fluid used in subterranean treatments to reduce friction.
Such subterranean treatments include, but are not limited to,
drilling operations, stimulation treatments (e.g., fracturing
treatments, acidizing treatments, fracture acidizing treatments),
and completion operations. Those of ordinary skill in the art, with
the benefit of this disclosure, will be able to recognize a
suitable subterranean treatment where friction reduction may be
desired.
The water used in the aqueous treatment fluids of the disclosed
subject matter can be freshwater, brackish water, saltwater (e.g.,
water containing one or more salts dissolved therein), brine (e.g.,
produced from subterranean formations), seawater, pit water, pond
water--or--the like, or combinations thereof. It is common for
freshwater to include total dissolved solids at a level of less
than 1000 ppm; brackish water to include total dissolved solids at
a level of 1,000 ppm to less than 10,000 ppm; saltwater to include
total dissolved solids at a level of 10,000 ppm to 30,000 ppm; and
brine to include total dissolved solids at a level of greater than
30,000 ppm. Generally, the water used may be from any source,
provided that it does not contain an excess of compounds that may
adversely affect other components in the aqueous treatment fluid or
the formation itself. The disclosed subject matter is effective in
all aqueous treating fluid waters.
The water soluble polymers of the present disclosure should be
included in the aqueous treatment fluids of the present disclosure
in an amount sufficient to provide the desired reduction of
friction. In some embodiments, a water soluble polymer of the
present disclosure may be present in an amount that is at least
about 0.0025%, in some cases at least about 0.003%, in other cases
at least about 0.0035% and in some instances at least about 0.05%
by weight of the aqueous treatment fluid and can be up to about 4%,
in some cases up to about 3%, in other cases up to about 2%, in
some instances up to about 1%, in other instances up to about
0.02%, in some situations up to less than about 0.1%, in other
situations, up to about 0.09%, and in specific situations, up to
about 0.08% by weight of the aqueous treatment fluid. The amount of
the water soluble polymers included in the aqueous treatment fluids
can be any value or range between any of the values recited
above.
In some embodiments, the water soluble polymer can be present in
aqueous treatment fluids in an amount in the range of from about
0.0025% to about 0.025%, in some cases in the range of from about
0.0025% to less than about 0.01%, in other cases in the range of
from about 0.0025% to about 0.009%, and in some situations in the
range of from about 0.0025% to about 0.008%, by weight of the
aqueous treatment fluid.
In some embodiments when the present water-in-oil emulsions are
used, the amount of water soluble polymer in the aqueous treatment
fluid can be at least about 5%, in some cases at least about 7.5%,
in other cases at least about 10%, in some instances at least about
12.5%, in other instances at least about 15%, in some situations at
least about 20%, and in other situations at least about 25% less
than when water-in-oil emulsion containing a polymer of the same
composition at a concentration of 30 weight percent or more are
used in the in the aqueous treatment fluid.
In embodiments of the disclosure, the water-in-oil emulsions
according to the disclosure are used in the friction reducing
treatment solution in an amount of at least about 0.1 gallons of
water-in-oil emulsion per thousand gallons of aqueous treating
fluid water (gpt), in some cases at least about 0.15 gpt, and in
other cases at least about 0.2 gpt and can be up to about 3 gpt, in
some cases up to about 2.5 gpt, in other cases up to about 2.0 gpt,
in some instances up to about 1.5 gpt, and in other instances up to
about 1.5 gpt. The amount of water-in-oil emulsion used in the
friction reducing treatment solution can be any value or range
between any of the values recited above.
In embodiments of the disclosed subject matter, the aqueous
treatment fluid contains 10,000 to 300,000 ppm of total dissolved
solids. In some embodiments, the total dissolved solids include at
least 10 weight percent of a multivalent cation. In many
embodiments, the any multivalent cation can be included and can
include one or more selected from iron (in its ferrous and ferric
forms), calcium, magnesium, manganese, strontium, barium, and
zinc.
In embodiments of the present disclosure, the aqueous treatment
fluid can include total dissolved solids at a level of at least
about 100 ppm, in some instances at least about 500 ppm, in other
instances at least about 1,000 ppm, in some cases at least about
5,000 ppm and in other cases at least about 10,000 ppm and can be
up to about 500,000 ppm, in certain cases up to about 400,000 ppm,
in many cases up to about 300,000 ppm, in some cases up to about
250,000 ppm, in other cases up to about 200,000 ppm, in some
instances up to about 100,000 ppm, in other instances up to about
50,000 ppm and in some situations up to about 25,000 ppm. The
amount of total dissolved solids in the aqueous treatment solution
can be any value or range between any of the values recited
above.
In embodiments of the present disclosure, the total dissolved
solids in the aqueous treatment fluid can contain multivalent
cations at a level of at least about 10%, in some cases at least
about 15% and in other cases at least about 20% and can be up to
about 50%, in some cases up to about 40% and in other cases up to
about 35% by weight of the total dissolved solids. The amount of
multivalent cation in the total dissolved solids in the aqueous
treatment solution can be any value or range between any of the
values recited above.
Additional additives can be included in the aqueous treatment
fluids of the present disclosure as deemed appropriate by one of
ordinary skill in the art, with the benefit of this disclosure.
Examples of such additives include, but are not limited to,
corrosion inhibitors, proppant particulates, acids, fluid loss
control additives, and surfactants. For example, an acid may be
included in the aqueous treatment fluids, among other things, for a
matrix or fracture acidizing treatment. In fracturing embodiments,
proppant particulates may be included in the aqueous treatment
fluids to prevent the fracture from closing when the hydraulic
pressure is released.
The aqueous treatment fluids of the present disclosure can be used
in any subterranean treatment where the reduction of friction is
desired. Such subterranean treatments include, but are not limited
to, drilling operations, stimulation treatments (e.g., fracturing
treatments, acidizing treatments, fracture acidizing treatments),
and completion operations. Those of ordinary skill in the art, with
the benefit of this disclosure, will be able to recognize a
suitable subterranean treatment where friction reduction may be
desired.
In some embodiments, the disclosed subject matter includes a method
of treating a portion of a subterranean formation that includes
providing the above-described aqueous treatment fluid and
introducing the aqueous treatment fluid into the portion of the
subterranean formation. In some embodiments, the aqueous treatment
fluid can be introduced into the portion of the subterranean
formation at a rate and pressure sufficient to create or enhance
one or more fractures in the portion of the subterranean formation.
The portion of the subterranean formation that the aqueous
treatment fluid is introduced will vary dependent upon the
particular subterranean treatment. For example, the portion of the
subterranean formation may be a section of a well bore, for
example, in a well bore cleanup operation. In the stimulation
embodiments, the portion may be the portion of the subterranean
formation to be stimulated.
The methods of the present disclosure can also include preparing
the aqueous treatment fluid. Preparing the aqueous treatment fluid
can include providing the water soluble polymer containing
water-in-oil emulsion and combining the water soluble polymer with
the water to from the aqueous treatment fluid.
The present disclosure will further be described by reference to
the following examples. The following examples are merely
illustrative and are not intended to be limiting. Unless otherwise
indicated, all percentages are by weight.
EXAMPLE 1
Preparation of Water-in-Oil Emulsion Polymers, Percentages
Expressed as Weight Percent of the Water-in-Oil Emulsion
Composition
The water-in-oil emulsion composition was prepared by combining
softened water, acrylamide, acrylic acid, acryloyloxyethyltrimethyl
ammonium chloride (AETAC), EDTA and 25% sodium hydroxide (to pH of
6.5) and stirring until uniform to form the aqueous phase (about
77.5%). The oil phase (about 21.5%) was made by combining an
aliphatic hydrocarbon liquid (about 20%) with surfactants
(ethoxylated amine (about 1.1%), sorbitan monooleate (about 0.15%),
and polyoxyalkylene sorbitan monooleate (about 0.25%) with mixing.
The aqueous phase was added to the oil phase with mixing to form a
dispersion of the aqueous phase dispersed in the continuous oil
phase. The dispersion was heated to an initiation temperature while
sparging with nitrogen and sodium metabisulfite and an oil soluble
peroxide initiator was added to the dispersion to initiate
polymerization. Typically, the oil phase was added to a glass resin
kettle and once agitation was begun, the aqueous phase was added to
the resin kettle. The resulting dispersion was sparged with
nitrogen for 30 minutes while the temperature was equilibrated to
25.degree. C., at which time 37 microliters of peroxide was added
to the stirring dispersion and 0.075% sodium metabisulfite (SMBS)
solution was fed to the dispersion at a rate of 0.1 milliliters per
minute. The polymerization temperature was controlled between
38.degree. and 42.degree. C. for approximately 90 minutes. Residual
monomers were scavenged by feeding 25% sodium metabisulfite (SMBS)
solution at a rate of 1.0 milliliters per minute. An inverting
surfactant (C.sub.12-C.sub.14 9 mole ethoxylate, 1.4%) was blended
into the water-in-oil polymer emulsion to aid in make-down on use
and the dispersion was subsequently cooled to room temperature. The
resulting water-in-oil emulsion contained about 30% of water
soluble polymer.
TABLE-US-00001 TABLE 1 Acrylamide AETAC Acrylic Acid Sample (%) (%)
(%) A 58 40 2 B 48 50 2 C 48 50 2 D 58 40 2 E (Comparative) 70 --
30
Friction Flow Loop Testing
A friction flow loop was constructed from 5/16'' inner diameter
stainless steel tubing, approximately 30 feet in overall length.
Test solutions were pumped out of the bottom of a tapered 5 gallon
reservoir. The solution flowed through the tubing and was returned
back into the reservoir. The flow is achieved using a plunger pump
equipped with a variable speed drive. Pressure is measured from two
inline gages, with the last gage located approximately 2 ft from
the discharge back into reservoir.
Four gallons of brine solution (weight percent of salt indicated
below) was prepared in the sample reservoir and the pump is started
and set to deliver a flow rate of 5-10 gal/min. The salt solution
is recirculated until the temperature equilibrates at 25.degree. C.
and a stabilized pressure differential is achieved. This pressure
is recorded as the "initial pressure" of the brine solution. The
test amount of neat water-in-oil emulsion polymer is quickly
injected with a syringe into the sample reservoir containing the
brine solution and a timer was started. The dose was recorded as
gallons of water-in-oil emulsion per thousand gallons of brine
solution (gpt). The pressure was recorded at 30 seconds, 1 min, 2
min and 3 min respectively. The pressure drop was calculated at
each time interval comparing it to the initial pressure
differential reading of the brine solution. The percentage friction
reduction was determined as described in U.S. Pat. No. 7,004,254 at
col. 9, line 36 to col. 10, line 43. The brine used was an aqueous
solution containing 165,000 ppm total dissolved solids including
about 43,430 ppm sodium, 3,670 ppm magnesium, 14,400 ppm calcium
and 103,290 ppm chloride. The results are shown in Table 2 below.
The dose is the amount of water-in-oil emulsion used as gallons per
thousand gallons of brine solution.
TABLE-US-00002 TABLE 2 Emulsion Friction Reduction (%) Run No.
Sample Dose (gpt) 30 sec. 1 min. 2 min. 3 min. 1 A 1 33.3 46.9 56.4
60.2 2 B 1 49.6 63.6 70.8 72 3 C 1 35.8 53.2 65.3 67.5 4 D 1 21.9
37.9 50.4 55.5 5 E 1 5.7 10.7 22.8 31.4
The data show an improvement in friction reduction provided by the
inventive water soluble polymers (Am/AA/AETAC) compared with
traditional Am/AA copolymers.
EXAMPLE 2
A water-in-oil emulsion polymer was prepared as in sample A in
example 1 (48/2/50 w/w Am/AA/AETAC) except the inverting surfactant
(C.sub.12-C.sub.14 ethoxylate) was varied from 7 to 9 moles of
ethoxylation as in Table 3 below.
TABLE-US-00003 TABLE 3 Ethoxylation Reduced Viscosity Sample
(moles) (dl/g) F 7 26.4 G 9 23.2
The samples were evaluated in a friction loop as described in
example 1.
TABLE-US-00004 TABLE 4 Emulsion Friction Reduction (%) Run No.
Sample Dose (gpt) 30 sec. 1 min. 2 min. 3 min. 6 F 1 28.5 47.7 59.6
62.3 7 G 1 58.2 61.9 63.8 64.6
Thus, the water-in-oil polymer emulsion polymers according to the
disclosure are able to provide excellent better friction reduction
performance in high brine solutions.
EXAMPLE 3
Water-in-oil emulsion polymers were prepared as in sample A in
example 1 (48/2/50 w/w Am/AA/AETAC) except the amount of inverting
surfactant (C.sub.12-C.sub.14 9-mole ethoxylate) was varied as
shown in Table 5 below.
TABLE-US-00005 TABLE 5 Reduced Viscosity Inverting Surfactant
Sample (dl/g) (wt. % of emulsion) H 27.1 1.1 I 27.1 1.2 J 27.1 1.3
K 27.1 1.4 L 27.1 1.5 M 27.1 1.75 N 27.1 2.0
The following samples were evaluated in a friction loop as
described in example 1, except The brine used was an aqueous
solution containing about 206,000 ppm total dissolved solids
including about 53,500 ppm sodium, about 4,600 ppm magnesium, about
18,000 ppm calcium and about 139,300 ppm chloride. The results are
shown in Table 6 below.
TABLE-US-00006 TABLE 6 Emulsion Friction Reduction (%) Run No.
Sample Dose (gpt) 30 sec. 1 min. 2 min. 3 min. 8 H 1 25.5 47.3 60.4
63.6 9 I 1 33.3 53.8 64.1 66.3 10 J 1 34.6 54.4 65.0 66.2 11 K 1
31.3 55.3 64.4 66.5 12 L 1 42.5 60.1 67.4 68.5
The following samples were evaluated in a friction loop as
described in example 1, except The brine used was an aqueous
solution containing about 247,000 ppm total dissolved solids
including about 65,010 ppm sodium, about 5,500 ppm magnesium, about
21.610 ppm calcium and about 154,930 ppm chloride. The results are
shown in Table 7 below.
TABLE-US-00007 TABLE 7 Emulsion Friction Reduction (%) Run No.
Sample Dose (gpt) 30 sec. 1 min. 2 min. 3 min. 13 M 1 64.9 69.8
70.5 70.5 14 N 1 70.4 71.5 71.1 71.1
Thus, the water-in-oil polymer emulsion polymers according to the
disclosure are able to provide excellent better friction reduction
performance in high brine solutions.
The disclosed subject matter has been described with reference to
specific details of particular embodiments thereof. It is not
intended that such details be regarded as limitations upon the
scope of the disclosed subject matter except insofar as and to the
extent that they are included in the accompanying claims.
Therefore, the exemplary embodiments described herein are well
adapted to attain the ends and advantages mentioned as well as
those that are inherent therein. The particular embodiments
disclosed above are illustrative only, as the exemplary embodiments
described herein exemplary embodiments described herein may be
modified and practiced in different but equivalent manners apparent
to those skilled in the art having the benefit of the teachings
herein. Furthermore, no limitations are intended to the details of
construction or design herein shown, other than as described in the
claims below. It is therefore evident that the particular
illustrative embodiments disclosed above may be altered, combined,
or modified and all such variations are considered within the scope
and spirit of the exemplary embodiments described herein. The
exemplary embodiments described herein illustratively disclosed
herein suitably may be practiced in the absence of any element that
is not specifically disclosed herein and/or any optional element
disclosed herein. While compositions and methods are described in
terms of "comprising," "containing," or "including" various
components or steps, the compositions and methods can also "consist
essentially of" or "consist of" the various components, substances
and steps. As used herein the term "consisting essentially of"
shall be construed to mean including the listed components,
substances or steps and such additional components, substances or
steps which do not materially affect the basic and novel properties
of the composition or method. In some embodiments, a composition in
accordance with embodiments of the present disclosure that
"consists essentially of" the recited components or substances does
not include any additional components or substances that alter the
basic and novel properties of the composition, e.g., the friction
reduction performance or viscosity of the composition. All numbers
and ranges disclosed above may vary by some amount. Whenever a
numerical range with a lower limit and an upper limit is disclosed,
any number and any included range falling within the range is
specifically disclosed. In particular, every range of values (of
the form, "from about a to about b," or, equivalently, "from
approximately a to b," or, equivalently, "from approximately a-b")
disclosed herein is to be understood to set forth every number and
range encompassed within the broader range of values. Also, the
terms in the claims have their plain, ordinary meaning unless
otherwise explicitly and clearly defined by the patentee. Moreover,
the indefinite articles "a" or "an," as used in the claims, are
defined herein to mean one or more than one of the element that it
introduces. If there is any conflict in the usages of a word or
term in this specification and one or more patent or other
documents that may be incorporated herein by reference, the
definitions that are consistent with this specification should be
adopted.
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