U.S. patent application number 15/894061 was filed with the patent office on 2019-02-14 for aqueous ampholyte polymer containing solutions for subterranean applications.
This patent application is currently assigned to SOLVAY USA INC.. The applicant listed for this patent is SOLVAY USA INC.. Invention is credited to Shih-Ruey Tom CHEN, HsinChen CHUNG, Kevin Walter FREDERICK, Yuntao Thomas HU, Randy Jack LOEFFLER, Michael A. McCABE, Narongsak TONMUKAYAKUL, Xiangnan YE.
Application Number | 20190048246 15/894061 |
Document ID | / |
Family ID | 51983819 |
Filed Date | 2019-02-14 |
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United States Patent
Application |
20190048246 |
Kind Code |
A1 |
CHUNG; HsinChen ; et
al. |
February 14, 2019 |
AQUEOUS AMPHOLYTE POLYMER CONTAINING SOLUTIONS FOR SUBTERRANEAN
APPLICATIONS
Abstract
A aqueous solution that includes water, from 100,000 to 300,000
ppm of dissolved solids, from 0.5 to 3 gallons per thousand gallons
of a water-in-oil emulsion, and an inverting surfactant. The
water-in oil emulsion includes an oil phase and an aqueous phase
where the oil phase is a continuous phase comprising an inert
hydrophobic liquid and the aqueous phase is present as dispersed
distinct particles in the oil phase. The aqueous phase contains
water, a water soluble polymer, and surfactants. The water soluble
polymer includes 30 to 50 weight percent of a non-ionic monomer, 5
to 15 weight percent of a sulfonic acid containing monomer, and 40
to 60 weight percent of a cationic monomer. The water soluble
polymer makes up from 10 to 35 weight percent of the water-in-oil
emulsion.
Inventors: |
CHUNG; HsinChen; (Houston,
TX) ; HU; Yuntao Thomas; (The Woodlands, TX) ;
YE; Xiangnan; (Cypress, TX) ; TONMUKAYAKUL;
Narongsak; (Spring, TX) ; McCABE; Michael A.;
(Duncan, OK) ; FREDERICK; Kevin Walter; (Evans
City, PA) ; CHEN; Shih-Ruey Tom; (Pittsburgh, PA)
; LOEFFLER; Randy Jack; (Carnegie, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SOLVAY USA INC. |
Princeton |
NJ |
US |
|
|
Assignee: |
SOLVAY USA INC.
Princeton
NJ
|
Family ID: |
51983819 |
Appl. No.: |
15/894061 |
Filed: |
February 12, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14292311 |
May 30, 2014 |
|
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15894061 |
|
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61829609 |
May 31, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 8/035 20130101;
C09K 8/62 20130101; C09K 8/725 20130101; C04B 28/02 20130101; C09K
8/80 20130101; C09K 8/74 20130101; E21B 43/26 20130101; C09K 8/36
20130101; C09K 8/512 20130101; C09K 8/887 20130101; C09K 8/52
20130101; C09K 8/68 20130101; C04B 2103/0062 20130101; C09K 8/82
20130101; C04B 24/163 20130101; C09K 8/467 20130101; C09K 8/76
20130101; C09K 8/882 20130101; E21B 43/16 20130101; C09K 8/12
20130101; C09K 8/64 20130101; C09K 2208/28 20130101; C09K 8/588
20130101; C09K 8/42 20130101; C04B 28/02 20130101; C04B 24/163
20130101 |
International
Class: |
C09K 8/12 20060101
C09K008/12; E21B 43/26 20060101 E21B043/26; C04B 24/16 20060101
C04B024/16; E21B 43/16 20060101 E21B043/16; C04B 28/02 20060101
C04B028/02; C09K 8/88 20060101 C09K008/88; C09K 8/82 20060101
C09K008/82; C09K 8/80 20060101 C09K008/80; C09K 8/76 20060101
C09K008/76; C09K 8/74 20060101 C09K008/74; C09K 8/72 20060101
C09K008/72; C09K 8/68 20060101 C09K008/68; C09K 8/64 20060101
C09K008/64; C09K 8/62 20060101 C09K008/62; C09K 8/588 20060101
C09K008/588; C09K 8/52 20060101 C09K008/52; C09K 8/512 20060101
C09K008/512; C09K 8/467 20060101 C09K008/467; C09K 8/42 20060101
C09K008/42; C09K 8/36 20060101 C09K008/36; C09K 8/035 20060101
C09K008/035 |
Claims
1. An aqueous solution comprising: water; from 100,000 to 300,000
ppm of dissolved solids; 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 30 to 50 weight percent of a non-ionic monomer, 5
to 15 weight percent of a sulfonic acid containing monomer, and 40
to 60 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.
2. The aqueous solution according to claim 1, wherein the cationic
monomer is methacrylamidopropyltrimethyl ammonium chloride or
acryloyloxyethyltrimethyl ammonium chloride.
3. The aqueous solution according to claim 1, wherein the nonionic
monomer is acrylamide.
4. The aqueous solution according to claim 1, wherein the sulfonic
acid containing monomer is 2-acrylamido-2-methylpropane sulfonic
acid.
5. The aqueous solution according to claim 1, wherein the dissolved
solids comprise 30 to 39 weight percent sodium, 0 to 9 weight
percent calcium, 0 to 3 weight percent magnesium and 58 to 62
weight percent chloride.
6. The aqueous solution according to claim 1, wherein the water
soluble polymer has a molecular weight in the range of from about
7,500,000 to about 20,000,000.
7. The aqueous 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 aqueous solution according to claim 1, wherein the
water-in-oil emulsion comprises at least one of an inhibitor, a
salt, or an inverting surfactant.
9. The aqueous solution according to claim 1, wherein the
water-in-oil emulsion comprises an ammonium salt.
10. The aqueous solution according to claim 1, wherein the
water-in-oil emulsion comprises 4-methoxyphenol.
11. The aqueous solution according to claim 1, wherein the
inverting surfactant is one or more selected from the group
consisting of polyoxyethylene alkyl phenol; polyoxyethylene (10
mole) cetyl ether; polyoxyethylene alkyl-aryl ether;
N-cetyl-N-ethyl morpholinium ethosulfate; sodium lauryl sulfate;
condensation products of higher fatty alcohols with ethylene oxide,
condensation products of alkylphenols and ethylene oxide,
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.
12. The aqueous solution according to claim 1, wherein the
inverting surfactant comprises one or more ethoxylated
C.sub.12-C.sub.16 alcohols.
13. The aqueous solution according to claim 1, wherein the inert
hydrophobic liquid comprises a mixture of paraffinic hydrocarbons
and napthenic hydrocarbons.
14. The aqueous 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.
15. The aqueous solution according to claim 1, wherein the aqueous
solution demonstrates better friction reduction properties than an
aqueous solution containing the same level of dissolved solids and
the same amount of a similarly prepared water soluble polymer that
contains only the same non-ionic monomers and cationic monomers,
but no sulfonic acid containing monomers.
16. An aqueous solution comprising: water; from 150,000 to 250,000
ppm of dissolved solids; 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 35 to 45 weight percent of a non-ionic monomer, 5
to 15 weight percent of a sulfonic acid containing monomer, and 45
to 55 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.
17. The aqueous solution according to claim 16, wherein the
non-ionic monomer comprises acrylamide, the sulfonic acid
containing monomer comprises sodium AMPSA, and the cationic monomer
comprises AETAC.
18. 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 35 to 45 weight percent of a non-ionic monomer, 5
to 15 weight percent of a sulfonic acid containing monomer, and 45
to 55 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.
19. The water-in-oil emulsion according to claim 18, wherein the
non-ionic monomer comprises acrylamide, the sulfonic acid
containing monomer comprises sodium AMPSA, and the cationic monomer
comprises AETAC.
20. The water-in-oil emulsion according to claim 18, wherein the
surfactants comprise a tall oil fatty acid diethanol amine, a
polyoxyethylene (5) sorbitan monooleate, and a sorbitan monooleate;
the inert hydrophobic liquid comprises a mixture of paraffinic
hydrocarbons and napthenic hydrocarbons; and the inverting
surfactant comprises one or more ethoxylated C.sub.12-C.sub.16
alcohols.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of priority of U.S.
Provisional Application Ser. No. 61/829,609 filed May 31, 2013
entitled "Ampholyte Polymeric Compounds in Subterranean
Applications" which is herein incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] At least some of the exemplary embodiments described herein
relate to compositions for treating subterranean zones. The
compositions include aqueous solutions that contain water soluble
polymers in a water-in-oil emulsion form and high total dissolved
solids.
2. Description of the Prior Art
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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 OF THE INVENTION
[0011] The present invention is directed to an aqueous solution
that includes water, from 100,000 to 300,000 ppm of dissolved
solids, from 0.5 to 3 gallons per thousand gallons of a
water-in-oil emulsion, and an inverting surfactant. The water-in
oil emulsion includes an oil phase and an aqueous phase where the
oil phase is a continuous phase comprising an inert hydrophobic
liquid and the aqueous phase is present as dispersed distinct
particles in the oil phase. The aqueous phase contains water, a
water soluble polymer, and surfactants. The water soluble polymer
includes 30 to 50 weight percent of a non-ionic monomer, 5 to 15
weight percent of a sulfonic acid containing monomer, and 40 to 60
weight percent of a cationic monomer. The water soluble polymer
makes up from 10 to 35 weight percent of the water-in-oil
emulsion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The following figures are included to illustrate certain
aspects of the exemplary embodiments described herein, and should
not be viewed as exclusive embodiments. The subject matter
disclosed is capable of considerable modifications, alterations,
combinations, and equivalents in form and function, as will occur
to those skilled in the art and having the benefit of this
disclosure.
[0013] FIG. 1 provides a graph of the viscosity of an ampholyte
polymeric compound at various concentrations over time at an
elevated temperature.
[0014] FIG. 2 provides a graph comparing the viscosity of an
ampholyte polymeric compound and a traditional viscosifier in
water.
[0015] FIG. 3 provides a graph comparing the viscosity of an
ampholyte polymeric compound and a traditional viscosifier in a
high TDS water.
[0016] FIG. 4 provides a graph of percent friction reduction at
various salinities for three friction reducing additives including
one ampholyte polymeric compound.
[0017] FIG. 5 provides a graph of viscosity measurements over time
at various temperatures for a fluid comprising an ampholyte
polymeric compound.
[0018] FIG. 6 provides a graph comparing the intrinsic viscosity
over time for a fluid comprising an ampholyte polymeric compound
and a fluid comprising a traditional friction reducing agent.
[0019] FIG. 7 provides a graph of viscosity measurements over time
at various TDS concentrations for fluids comprising an ampholyte
polymeric compound.
DETAILED DESCRIPTION
[0020] 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 exemplary
embodiments described herein. 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.
[0021] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the exemplary embodiments
described herein 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.
[0022] 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.
[0023] As used herein, the term "ampholyte" refers to a compound
having both a positive and a negative charge. The ampholyte
polymers described herein include nonionic monomers, cationic
monomers, and sulfonic acid-containing monomers.
[0024] As used herein, the term "polymer" is meant to encompass
oligomer, and includes, without limitation, both homopolymers and
copolymers.
[0025] 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.
[0026] 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.
[0027] The exemplary embodiments described herein provide, in some
instances, an aqueous ampholyte polymer solutions that includes
water, from 100,000 to 300,000 ppm of dissolved solids, from 0.5 to
3 gallons per thousand gallons of a water-in-oil emulsion, and an
inverting surfactant. In some instances, the water-in oil emulsion
includes an oil phase and an aqueous phase where the oil phase is a
continuous phase comprising an inert hydrophobic liquid and the
aqueous phase is present as dispersed distinct particles in the oil
phase. In some instances, the aqueous phase contains water, a water
soluble polymer (also referred to as an ampholyte polymeric
compound), and surfactants. In some instances, the water soluble
polymer includes 30 to 50 weight percent of a non-ionic monomer, 5
to 15 weight percent of a sulfonic acid containing monomer, and 40
to 60 weight percent of a cationic monomer. In some instances, the
water soluble polymer makes up from 10 to 35 weight percent of the
water-in-oil emulsion.
[0028] The ampholyte polymers described herein (also referred to as
water soluble polymers) are suitable for friction reduction in
treatment fluids, including in high TDS treatment fluids (e.g.,
treatment fluids with saltwater or brackish water base fluids).
Further, the ampholyte polymers described herein advantageously
provide for single-component friction reduction agents that reduce
implementation complexity as compared to the multi-component
friction reducing systems described above. Together, these
properties and advantages provide for friction reducing agents
having enhanced operational efficacy, reduce the energy
requirement, and reduce the cost of the treatment.
[0029] Further, the aqueous ampholyte polymer solutions described
herein may advantageously break over time with the use of little or
no breaker. Without being limited by theory, it is believed that,
at least some of the monomeric units of the ampholyte polymers may
at least partially hydrolyze, which in turn may cause the ampholyte
polymeric compound to contract and reduce its friction reducing
effect. As used herein, the terms "partially hydrolyze," "partially
hydrolysis," and the like refer to hydrolysis of at least some of
the monomeric units of a polymeric compound (e.g., ampholyte
polymers described herein). Partial hydrolysis and polymeric
contraction of an ampholyte polymeric compound described herein may
advantageously allow wellbore operations to be performed with
minimal amounts of breaker in the treatment fluid and/or without
the need for a subsequent breaking treatment (and perhaps in some
instances, without any breaker or need for subsequent breaking
treatments), which reduces the cost and time associated with the
wellbore operations.
[0030] The aqueous ampholyte polymer solutions of the exemplary
embodiments described herein may, in some embodiments, include
water, dissolved solids, and a water-in-oil emulsion that contains
a copolymer.
[0031] The water-in-oil emulsions described herein include an oil
phase, an aqueous phase and surfactants.
[0032] In some embodiments, 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.
Without being limited by theory, it is believe that when the O/A
ratio is too oil heavy, the polymer may be too concentrated in the
aqueous phase. In some instances, 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.
[0033] 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 ExxonMobile
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.
[0034] 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.
[0035] In some embodiments, 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.
[0036] 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 exemplary embodiments
described herein. In some embodiments, 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.
[0037] 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.
[0038] 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 alkylamines; sodium hexadecyl phthalate;
sodium decyl phthalate; and oil-soluble alkanolamides.
[0039] In some embodiments, 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.
[0040] In some embodiments, 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. Without being limited by theory, it is
believe that 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. In some embodiments, 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.
[0041] The aqueous phase is present in the water-in-oil emulsion as
a dispersed phase of distinct particles in the oil phase and
includes water and a water soluble polymer. In some embodiments,
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.
[0042] In some embodiments, the water soluble polymer is present at
a level of at least about 10, in some cases at least about 15, and
in other cases at least about 25 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 to treat a portion
of a subterranean formation may be uneconomical. However, when the
amount of water soluble polymer is too high, the performance of the
water soluble polymer may be less than optimum. 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.
[0043] In some embodiments, 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
sulfonic acid containing monomers included at a level that provides
the desired amount of water soluble polymer.
[0044] In some embodiments, the monomer mixture typically includes
acrylamide as a non-ionic monomer. In some embodiments, the amount
of non-ionic monomer can be at least about 30, 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. Without being limited
by theory, it is believe that when the amount of non-ionic monomer
is too low, the molecular weight of the resulting water soluble
polymer may be lower than desired. In some embodiments, the amount
of non-ionic monomer in the monomer mixture can be up to about 50,
in some case up to about 47.5, and in other cases up to about 45
weight percent based on the weight of the monomer mixture. Without
being limited by theory, it is believe that when the amount of
non-ionic monomer is too high, the water soluble polymer may not
carry enough ionic charge to optimally function as intended. The
amount of non-ionic monomer in the monomer mixture can be any value
or range between any of the values recited above.
[0045] In some embodiments, the non-ionic monomer is
acrylamide.
[0046] In many embodiments, the monomer mixture includes a sulfonic
acid containing monomer or its corresponding salts. In some
embodiments, the sulfonic acid containing monomer is the sodium
salt of 2-acrylamido-2-methylpropane sulfonic acid (AMPSA). In some
embodiments, the amount of sulfonic acid containing monomer can be
at least about 5, in some cases at least about 6, and in other
cases at least about 8 weight percent based on the weight of the
monomer mixture. Without being limited by theory, it is believe
that when the amount of sulfonic acid containing monomer is too
low, the water soluble polymer may not carry enough anionic charge
to optimally function as intended. In some embodiments, the amount
of sulfonic acid containing monomer in the monomer mixture can be
up to about 15, in some case up to about 14, and in other cases up
to about 12 weight percent based on the weight of the monomer
mixture. Without being limited by theory, it is believe that when
the amount of sulfonic acid containing monomer is too high, the
water soluble polymer may have undesirable flocculation properties
when used in some embodiments. The amount of sulfonic acid
containing monomer in the monomer mixture can be any value or range
between any of the values recited above.
[0047] In many embodiments, the monomer mixture includes a cationic
monomer or its corresponding salts, non-limiting examples being
chloride salts. Particular useful examples of cationic monomers
include, but are not limited to, methacrylamidopropyltrimethyl
ammonium chloride (MAPTAC) and acryloyloxyethyltrimethyl ammonium
chloride (AETAC). In some embodiments, the amount of cationic
monomer can be at least about 40, in some cases at least about
42.5, and in other cases at least about 45 weight percent based on
the weight of the monomer mixture. Without being limited by theory,
it is believe that when the amount of cationic monomer is too low,
the water soluble polymer may not carry enough cationic charge to
optimally function as intended. In some embodiments, the amount of
cationic monomer in the monomer mixture can be up to about 60, 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. Without
being limited by theory, it is believe that 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.
[0048] Typically, the composition of the water soluble polymer will
be the same or about the same as the composition of the monomer
mixture.
[0049] Not being limited to any single theory, it is believed that
the water soluble polymers described herein do not significantly
decrease their hydrodynamic volume due to the presence of ions in
the aqueous solution as is the case with prior art water soluble
polymers.
[0050] The water-in-oil emulsion may, in some embodiments, 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.).
[0051] Thus, the water soluble polymers in the dispersed aqueous
phase particles of the water-in-oil emulsions described herein are,
in some embodiments, able to provide a greater friction reducing
effect by reducing the energy losses due to friction in high
dissolved solids containing aqueous solutions. As a non-limiting
example, the water soluble polymers described herein can reduce
energy losses during introduction of the aqueous into a well bore
due to friction between the aqueous solution in turbulent flow and
the formation and/or tubular good(s) (e.g., a pipe, coiled tubing,
etc.) disposed in the well bore.
[0052] In some embodiments, 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.
[0053] In some embodiments, 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.
[0054] 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.
[0055] In some embodiments, 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.
[0056] In some embodiments, the polymerization technique may have
an initiation temperature of about 25.degree. C. and proceed
approximately adiabatically. In other embodiments, the
polymerization can be carried out isothermally at a temperature of
about from 37.degree. C. to about 50.degree. C.
[0057] 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.
[0058] 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.
[0059] The water soluble polymers described herein typically have a
molecular weight sufficient to provide desired rheological
properties in the aqueous ampholyte polymer solutions. In some
embodiments, the water soluble polymers described herein may 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 present copolymers may be in the range of
from about 2,000,000 to about 20,000,000, as determined using
intrinsic viscosity. 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 ampholyte polymer solutions.
[0060] 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.
[0061] Alternatively, the reduced viscosity of the water soluble
polymer at 0.05 wt. % concentration is used to measure molecular
size. In some embodiments, 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.
[0062] Suitable water soluble polymers described herein can be in
an acid form or in a salt form. A variety of salts can be made by
neutralizing the acid form sulfonic 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" or "ampholyte polymeric compound" is intended to include
both the acid form of the water soluble copolymer and its various
salts.
[0063] In some embodiments, the water-in-oil emulsion is added to
water by inverting the emulsion to form an aqueous 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.
[0064] 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.
[0065] In some embodiments, 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
solution described herein. As those of ordinary skill in the art
will appreciate, with the benefit of this disclosure, upon addition
to the aqueous solution, the water-in-oil emulsion should invert,
releasing the copolymer into the aqueous solution.
[0066] 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).
[0067] In some embodiments, 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.
[0068] A specific non-limiting example of a suitable inverting
surfactant includes an ethoxylated C.sub.12-C.sub.16 alcohol. 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 solution. In some embodiments, the inverting
surfactant can be present in an amount in the range of from about
1% to about 5%, in some cases from about 1.5% to about 3.5% by
weight of the water-in-oil emulsion.
[0069] In some embodiments, the inverting surfactants are added to
the water-in-oil emulsion after the polymerization is
completed.
[0070] In some embodiments, 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. In some instances, the
this period of time is significantly reduced when using the water
soluble polymers described herein.
[0071] 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. Non-limiting examples of suitable static mixers can be
found in U.S. Pat. Nos. 4,051,065 and 3,067,987.
[0072] In some embodiments, once the water soluble polymer
containing water-in-oil emulsion is made down into water, any other
additives are added to the aqueous ampholyte polymer solutions.
[0073] In some embodiments, the aqueous solution containing water
soluble polymers described herein can be included in any aqueous
treatment fluid used in subterranean treatments to reduce friction.
Such subterranean treatments may 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.
[0074] In some embodiments, the water used in the aqueous ampholyte
polymer solutions described herein can be freshwater, 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. 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 ampholyte polymer solution.
[0075] In some embodiments, the water soluble polymers described
herein should be included in the aqueous ampholyte polymer solution
in an amount sufficient to provide the desired reduction of
friction. In some embodiments, a water soluble polymer described
herein 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 solution 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 solution. The amount of the water soluble polymers included
in the aqueous solution can be any value or range between any of
the values recited above.
[0076] In some embodiments, the water soluble polymer described
herein can be present in aqueous solution 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 solution.
[0077] In some embodiments, the water-in-oil emulsions described
herein are used in the aqueous ampholyte polymer solution in an
amount of at least about 0.1 gallons of water-in-oil emulsion per
thousand gallons of aqueous solution (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 aqueous solution can be any value
or range between any of the values recited above.
[0078] In some embodiments, the aqueous ampholyte polymer solution
contains 100,000 to 300,000 ppm of total dissolved solids. In some
embodiments, the total dissolved solids include sodium chloride. In
some embodiments, the dissolved solids include 30 to 39 weight
percent sodium, 0 to 9 weight percent calcium, 0 to 3 weight
percent magnesium and 58 to 62 weight percent chloride.
[0079] In some embodiments, the aqueous ampholyte polymer solution
can include total dissolved solids at a level of at least about
100,000 ppm, in some cases at least about 125,000 ppm and in other
cases at least about 150,000 ppm and can be up to about 300,000
ppm, in some cases up to about 275,000 ppm and in other cases up to
about 250,000 ppm. The amount of total dissolved solids in the
aqueous ampholyte polymer solution can be any value or range
between any of the values recited above.
[0080] Additional additives can, in some embodiments, be included
in the aqueous ampholyte polymer solutions described herein 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 ampholyte polymer
solutions.
[0081] In some embodiments, the aqueous ampholyte polymer solutions
described herein 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.
[0082] In some embodiments, the present aqueous ampholyte polymer
solutions demonstrate better friction reduction properties than
aqueous solutions containing the same high levels of dissolved
solids and water soluble polymers that contain only the same
non-ionic monomers and cationic monomers, but no sulfonic acid
containing monomers.
EXAMPLES
[0083] The exemplary embodiments described herein will further be
described by reference to the following examples. The following
examples are merely illustrative of the exemplary embodiments
described herein and are not intended to be limiting. Unless
otherwise indicated, all percentages are by weight.
Example 1
[0084] Two samples of an ampholyte polymeric compound comprising a
terpolymer of acrylamide, 2-acrylamido-2-methylpropane sulfonic
acid, and acryloyloxy ethyl trimethyl ammonium chloride in water
were prepared at 5 gal/1,000 gal and 20 gal/1,000 gal. The samples
were heated from 77.degree. F. to 150.degree. F. at a rate of
10.degree. F./min and then held at a constant temperature of
150.degree. F. As shown in FIG. 1, the viscosity at the higher
concentration reduces from about 155 cP to less than about 5 cP in
about 90 minutes, while at the lower concentration from about 35 cP
to less than about 5 cP in about 20-25 minutes.
[0085] This example illustrates that treatment fluids comprising
the aqueous ampholyte polymer solutions described herein reduce in
viscosity over time (i.e., break over time), which may
advantageously allow for the use of little to no breaker in the
treatment fluids or in subsequent wellbore operations.
Example 2
[0086] Samples were prepared with (1) linear xanthan (known to
viscosify high TDS fluids) at 60 lb/1,000 gal and (2) an ampholyte
polymeric compound comprising a terpolymer of acrylamide,
2-acrylamido-2-methylpropane sulfonic acid, and acryloyloxy ethyl
trimethyl ammonium chloride at 60 gal/1,000 gal, each in base
fluids of (1) water and (2) salt water with an additional 3% KCl.
The viscosity of each same in were analyzed at 77.degree. F. and
150.degree. F. FIG. 2 (water samples) illustrates that the
ampholyte polymeric compound provides higher viscosity than linear
xanthan in water. While FIG. 3 (salt water samples) illustrates
that in a high TDS environment the ampholyte polymeric compound
provides for a comparable viscosity to linear xanthan.
[0087] This example illustrates that treatment fluids can be
viscosified to levels comparable to that of traditional
viscosifying agents, including in high TDS fluids.
Example 3
[0088] Samples were prepared with individual friction reducers at a
concentration of 1 gallon per thousand gallons (i.e., 0.1% by
volume) in water: [0089] (1) a commercially available friction
reducing containing partially hydrolyzed polyacrylamide; [0090] (2)
a multi-component, cationic friction reducing agent [0091] (3) an
ampholyte polymeric compound comprising a terpolymer of acrylamide,
2-acrylamido-2-methylpropane sulfonic acid, and acryloyloxy ethyl
trimethyl ammonium chloride.
[0092] The salinity of the samples (measured as ppm of TDS) was
then increased as the percent friction reduction ("% FR") was
analyzed by pumping the sample through a test pipe while measuring
the pressure drop with a pressure transducer. The % FR is
calculated based on the ratio between the measured pressure drop of
the sample and the pressure drop of a fresh water control sample at
the same tested flow rate and ambient temperature and pressure.
[0093] As shown in FIG. 4, the Sample 1 showed an immediate decline
in the % FR with increased salinity and a dramatic drop in % FR to
essentially no friction reduction from about 100,000 to about
150,000 ppm TDS. Samples 2 and 3 showed similar performance over
the salinity range tested with only about a 5%-10% variations in
the % FR from 0 ppm to about 250,000 ppm TDS.
[0094] This example demonstrates that the one-component friction
reducing agent of an ampholyte polymeric compound outperforms other
polymeric friction reducing agents with increased TDS and provides
comparable performance to the more complex friction reducing agents
tend to be expensive and complicated to implement.
Example 4
[0095] Samples of an ampholyte polymeric compound comprising a
terpolymer of acrylamide, 2-acrylamido-2-methylpropane sulfonic
acid, and acryloyloxy ethyl trimethyl ammonium chloride in water
were analyzed for degradation rates by analyzing the viscosity of
the fluid over time at various temperatures: [0096] (1) room
temperature, [0097] (2) ramp to 150.degree. F., and [0098] (3) ramp
to 190.degree. F.
[0099] As shown in FIG. 5, the viscosity of the room temperature
sample decreased from about 4.75 cP to about 1 cP over about 6
hours while the 150.degree. F. sample decreased from about 5 cP to
about 0.4 cP over about 25 minutes and the 190.degree. F. sample
decreased from about 5 cP to about 0.4 cP over about 15 minutes.
Reduction in viscosity to such levels indicates that the polymer is
partially hydrolyzed and contracted. As shown, the hydrolysis is
temperature dependent indicating that in some instances the native
temperature of the subterranean formation may be such that an
ampholyte polymeric compound may be capable of breaking with
minimal to no additional breaker.
Example 5
[0100] Samples were prepared with (1) partially hydrolyzed
polyacrylamide in water (2) an ampholyte polymeric compound
comprising a terpolymer of acrylamide, 2-acrylamido-2-methylpropane
sulfonic acid, and acryloyloxy ethyl trimethyl ammonium chloride in
water. The concentration of each of the polymers was at infinite
dilution, which is a term known in the art that one of ordinary
skill in the art can determine. The intrinsic viscosity of the
samples were measured over about 75 hours. As illustrated in FIG.
6, the ampholyte polymeric compound sample reduced in intrinsic
viscosity from about 95 dL/g to about 5 dL/g, while the
polyacrylamide sample had a relatively steady intrinsic viscosity
of about 100 dL/g over the 75 hour time frame. This demonstrates
that the aqueous ampholyte polymer solutions may be capable of
breaking over time without the use of chemical breakers due, at
least in part, to the partial hydrolysis of the ampholyte polymeric
compound (e.g., the acryloyloxy ethyl trimethyl ammonium chloride
to acrylic acid).
Example 6
[0101] Samples were prepared with an ampholyte polymeric compound
comprising a terpolymer of acrylamide, 2-acrylamido-2-methylpropane
sulfonic acid, and acryloyloxy ethyl trimethyl ammonium chloride at
0.1 vol % in (1) water, (2) 50,000 ppm brine, and (3) 250,000 ppm
brine. The samples were heated to 150.degree. F., and the viscosity
of each sample was analyzed. FIG. 7 illustrates that sample in
water achieved the highest initial viscosity, while both of the
brine samples achieved about 1/3 the initial viscosity as the water
sample. However, over time, the higher the TDS of the sample the
less reduction in the viscosity (i.e., less hydrolysis and
contraction of the ampholyte polymeric compound).
Example 7
[0102] Samples were prepared with (1) 0.1 vol % polyacrylamide, (2)
0.1 vol % polyacrylamide and 1 lb/1,000 gal of a chemical breaker,
and (3) 0.1 vol % of an ampholyte polymeric compound comprising a
terpolymer of acrylamide, 2-acrylamido-2-methylpropane sulfonic
acid, and acryloyloxy ethyl trimethyl ammonium chloride in water.
Samples were run through various core/sand pack samples to
determine the regain permeability of the core/sand pack samples
after treatment.
[0103] In the regain permeability tests, the initial permeability
was measured by flowing 7% KCl through the core/sand pack sample.
Then, the samples were pumped through the core/sand pack sample at
a rate of five pore volumes. The treated core/sand pack sample was
shut-in overnight at 150.degree. F. The permeability was once again
tested by flowing 7% KCl through the core/sand pack sample. Table 1
provides the initial permeability and percent of permeability
regained.
TABLE-US-00001 TABLE 1 Initial Regain Fluid Sample Core/Sand Pack
Permeability Permeability (2) 100 mesh sand pack 1.5 D 96% (3) 100
mesh sand pack 1.6 D 98% (1) Berea core 91 mD 29% (2) Berea core
106 mD 83% (3) Berea core 77 mD 80% (2) Nugget 2.5 mD 54% (3)
Nugget 1.8 mD 61%
[0104] This example demonstrates that the ampholyte polymeric
compound, with no additional chemical breaker, provides for similar
or better regain in permeability to a traditional friction reducer
with a chemical breaker.
[0105] 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 and steps.
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.
Example 8
[0106] Preparation of Water-in-Oil Emulsion Polymers, Percentages
Expressed as Weight Percent of the Water-in-Oil Emulsion
Composition.
[0107] The water-in-oil emulsion composition were prepared by
combining softened water, acrylamide, cationic monomer, sulfonic
acid containing monomer (as detailed in the table below), 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 (about
1%) 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-00002 Acrylamide Cationic Monomer Acid Functional Monomer
Sample (%) (%) (%) A 40 50 (AETAC) 10 (NaAMPSA) Comparative Prior
Art Examples B 40 60 (AETAC) -- C 70 -- 30 (acrylic acid)
[0108] Friction Flow Loop Testing
[0109] 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.
[0110] 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 high dissolved solids 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
results are shown in the table below, dose is the amount of
water-in-oil emulsion used as gallons per thousand gallons of brine
solution.
TABLE-US-00003 Dissolved Friction Reduction (%) Emulsion Solids
Dose 30 1 2 3 Run No. Sample (ppm NaCl) (gpt) sec. min. min. min. 1
A 150,000 1 46.8 61.6 72.2 74.7 Comparative Prior Art Examples 2 B
150,000 1 34.1 53 69.4 72.8 3 C 150,000 1 10.2 15.7 21.5 27.8
[0111] The data show that the inventive aqueous ampholyte polymer
solutions demonstrates better friction reduction properties than
aqueous polymer solutions containing prior art copolymers.
[0112] Thus, the water-in-oil polymer emulsion polymers described
herein are able to provide significantly better friction reduction
performance in high dissolved solids solutions compared to the
prior art water-in-oil polymer emulsion polymers.
Example 9
[0113] A water-in-oil emulsion polymer (Sample D) was prepared as
described in Example 8 having 24.6% active polymer having a
composition of 40 wt. % acrylamide, 10 wt. % NaAMPSA, and 50 wt. %
AETAC. Samples B and C were used as comparative examples again. The
water-in-oil emulsion polymer was tested in a friction flow loop as
described in Example 8, where the water contained dissolved solids
having the following ratios: 29.4% Na, 7.4% Ca, 1.2% Mg, and 62% CI
at the total dissolved solids level indicated.
TABLE-US-00004 Dissolved Friction Reduction (%) Emulsion Solids
Dose 30 1 2 3 Sample (ppm) (gpt) sec. min. min. min. D 183,000 1 64
70.1 71.5 71 D 183,000 1.25 65.9 71.9 72.8 72.8 D 218,000 1 63.2
69.5 69.5 68.6 D 218,000 1.25 67.3 69.5 69.5 68.6 D 256,000 1 57.3
64 64 67.1 D 256,000 1.25 68 70.2 69.8 69.8 Comparative B 183,000 1
52.7 54.6 55.6 56.7 C 183,000 1 10.0 14.2 15.8 19.2 B 183,000 1.25
54.8 57.2 57.1 57.4 C 183,000 1.25 12.0 16.7 19.8 20.6 B 256,000 1
48.4 52.1 52.1 53.1 C 256,000 1 8.0 9.2 10.3 11.1 B 256,000 1.25
45.4 56.8 56.5 57.8 C 256,000 1.25 7.8 8.5 10.5 10.9
[0114] The data show that the inventive aqueous ampholyte polymer
solutions demonstrates better friction reduction properties than
aqueous polymer solutions containing prior art copolymers.
[0115] Thus, the water-in-oil polymer emulsion polymers described
herein are able to provide significantly better friction reduction
performance in high dissolved solids solutions compared to the
prior art water-in-oil polymer emulsion polymers.
[0116] The exemplary embodiments have 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 exemplary embodiments.
[0117] 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 and steps.
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.
* * * * *