U.S. patent application number 16/069167 was filed with the patent office on 2020-02-27 for surface-active two-tailed hydrophobic associated polymer and preparation method thereof.
This patent application is currently assigned to SOUTHWEST PETROLEUM UNIVERSITY. The applicant listed for this patent is SOUTHWEST PETROLEUM UNIVERSITY. Invention is credited to Yongming LI, Qiang REN, Liehui ZHANG, Jinzhou ZHAO.
Application Number | 20200062881 16/069167 |
Document ID | / |
Family ID | 59537046 |
Filed Date | 2020-02-27 |
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United States Patent
Application |
20200062881 |
Kind Code |
A1 |
LI; Yongming ; et
al. |
February 27, 2020 |
SURFACE-ACTIVE TWO-TAILED HYDROPHOBIC ASSOCIATED POLYMER AND
PREPARATION METHOD THEREOF
Abstract
The present invention provides a surface-active two-tailed
hydrophobic associated polymer and a preparation method thereof.
The surface-active two-tailed hydrophobic associated polymer is
prepared using a micellar free radical copolymerization method
including: adding a surfactant sodium lauryl sulfate and a
hydrophobic monomer N-phenethyl-N-alkyl (methyl) acrylamide or
N-benzyl-N-alkyl (methyl) acrylamide into an aqueous solution
containing acrylamide, acrylic acid,
2-acrylamide-2-methylpropanesulfonic acid, and surface-active
macromonomer polyoxyethylene lauryl ether (methyl) acrylate,
wherein the surfactant is used to solubilize the hydrophobic
monomer in the formed micelle; adjusting pH to 6-8 with sodium
hydroxide, and copolymerizing the hydrophobic monomer and a
water-soluble monomer by means of photoinitiation. The properties,
such as viscosifying property, temperature resistance, salt
resistance and hydrolysis resistance, of the hydrophobic associated
polymer can be effectively improved. The preparation method is
reliable in principle and simple in operation and has a wide market
prospect.
Inventors: |
LI; Yongming; (Chengdu,
CN) ; REN; Qiang; (Chengdu, CN) ; ZHAO;
Jinzhou; (Chengdu, CN) ; ZHANG; Liehui;
(Chengdu, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SOUTHWEST PETROLEUM UNIVERSITY |
Chengdu |
|
CN |
|
|
Assignee: |
SOUTHWEST PETROLEUM
UNIVERSITY
Chengdu
CN
|
Family ID: |
59537046 |
Appl. No.: |
16/069167 |
Filed: |
May 22, 2017 |
PCT Filed: |
May 22, 2017 |
PCT NO: |
PCT/CN2017/085329 |
371 Date: |
July 10, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 8/584 20130101;
C09K 8/725 20130101; C09K 8/882 20130101; C08F 283/06 20130101;
C09K 8/68 20130101; C08F 283/065 20130101; C08F 283/06 20130101;
C08F 220/56 20130101; C08F 220/06 20130101; C08F 220/60
20130101 |
International
Class: |
C08F 283/06 20060101
C08F283/06; C09K 8/584 20060101 C09K008/584; C09K 8/72 20060101
C09K008/72 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2017 |
CN |
201710342098.2 |
Claims
1. A surface-active two-tailed hydrophobic associated polymer,
comprising a structural formula as follows: ##STR00003## wherein in
the formula, x, y, z, m, and n are percentages of a first
structural units; and x is 75 to 85%, y is 10 to 20%, z is 0 to 5%,
m is 0.1 to 0.2%, n is 0.2 to 0.5%; and x+y+z+m+n is 1; a and b are
numbers of a second structural units, c is the number of a third
structural unit, and a is 7, 9, 11, 13 or 15, b is 1 or 2, and c is
5, 7, 10, 23 or 40; and R.sub.1 and R.sub.2 are CH.sub.3 or H.
2. The surface-active two-tailed hydrophobic associated polymer
according to claim 1, wherein the surface-active two-tailed
hydrophobic associated polymer has a viscosity average molecular
weight of 100 to 10,000,000.
3. A preparation process of the surface-active two-tailed
hydrophobic associated polymer according to claim 1, sequentially
comprising the following steps: (1) adding acrylamide, acrylic
acid, 2-acrylamide-2-methylpropanesulfonic acid, and surface-active
macromonomer polyoxyethylene lauryl ether (methyl) acrylate to
distilled water to obtain a first solution, stirring uniformly,
adjusting pH of the first solution to 6-8 with sodium hydroxide to
obtain a second solution, adding a hydrophobic monomer
N-phenethyl-N-alkyl (methyl) acrylamide or N-benzyl-N-alkyl
(methyl) acrylamide and a surfactant sodium lauryl sulfate to the
second solution to obtain a third solution, and stirring till the
third solution is clear and transparent, a total mass percentage of
reaction monomers of the third solution is 25 to 30 wt %, wherein
the acrylamide accounts for 20 to 21.5 wt %, the acrylic acid
accounts for 3.5 to 5 wt %, the
2-acrylamide-2-methylpropanesulfonic acid accounts for 0 to 2 wt %,
the polyoxyethylene lauryl ether (methyl) acrylate accounts for 0.2
to 0.6 wt %, the N-phenethyl-N-alkyl (methyl) acrylamide or the
N-benzyl-N-alkyl (methyl) acrylamide accounts for 0.2 to 0.6 wt %,
and the sodium lauryl sulfate accounts for 0.8 to 2.0 wt %; (2)
introducing nitrogen for 15 min to remove dissolved oxygen in the
distilled water of the third solution to obtain a fourth solution;
and (3) adding a photoinitiator to the fourth solution and reacting
for 3 to 5 h at 10 to 30.degree. C. under a photoinitiation device
to obtain a viscous white colloid, the viscous white colloid is the
surface-active two-tailed hydrophobic associated polymer.
4. The preparation of the surface-active two-tailed hydrophobic
associated polymer according to claim 3, wherein the photoinitiator
is azobis (isobutylamidine hydrochloride) or
2-hydroxyl-4'-(2-hydroxyethoxy)-2-methylpropiophenone.
5. The preparation process of the surface-active two-tailed
hydrophobic associated polymer according to claim 2, sequentially
comprising the following steps: (1) adding acrylamide, acrylic
acid, 2-acrylamide-2-methylpropanesulfonic acid, and surface-active
macromonomer polyoxyethylene lauryl ether (methyl) acrylate to
distilled water to obtain a first solution, stirring uniformly,
adjusting pH of the first solution to 6-8 with sodium hydroxide to
obtain a second solution, adding a hydrophobic monomer
N-phenethyl-N-alkyl (methyl) acrylamide or N-benzyl-N-alkyl
(methyl) acrylamide and a surfactant sodium lauryl sulfate to the
second solution to obtain a third solution, and stirring till the
third solution is clear and transparent, a total mass percentage of
reaction monomers of the third solution is 25 to 30 wt %, wherein
the acrylamide accounts for 20 to 21.5 wt %, the acrylic acid
accounts for 3.5 to 5 wt %, the
2-acrylamide-2-methylpropanesulfonic acid accounts for 0 to 2 wt %,
the polyoxyethylene lauryl ether (methyl) acrylate accounts for 0.2
to 0.6 wt %, the N-phenethyl-N-alkyl (methyl) acrylamide or the
N-benzyl-N-alkyl (methyl) acrylamide accounts for 0.2 to 0.6 wt %,
and the sodium lauryl sulfate accounts for 0.8 to 2.0 wt %; (2)
introducing nitrogen for 15 min to remove dissolved oxygen in the
distilled water of the third solution to obtain a fourth solution;
and (3) adding a photoinitiator to the fourth solution and reacting
for 3 to 5 h at 10 to 30.degree. C. under a photoinitiation device
to obtain a viscous white colloid, the viscous white colloid is the
surface-active two-tailed hydrophobic associated polymer.
6. The preparation of the surface-active two-tailed hydrophobic
associated polymer according to claim 5, wherein the photoinitiator
is azobis (isobutylamidine hydrochloride) or
2-hydroxyl-4'-(2-hydroxyethoxy)-2-methylpropiophenone.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the national phase entry of
International Application NO. PCT/CN2017/085329, filed on May 22,
2017, which is based upon and claims priority to Chinese Patent
Application No. 2017103420982, filed on May 16, 2017, the entire
contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a surface-active two-tailed
hydrophobic associated polymer for an oilfield to increase a
recovery rate and perform acid fracturing, and a preparation method
thereof.
BACKGROUND
[0003] Traditional polymers, such as partially hydrolyzed
polyacrylamide (HPAM), have poor temperature resistance, salt
resistance, and shear resistance. Under high-temperature and
high-salt conditions of an oil reservoir, the viscosity of a
polymer solution drastically decreases due to hydrolysis, thermal
degradation, chain curling and the like of HPAM, and therefore the
requirements for enhanced oil recovery and acid fracturing of the
high-temperature and high-salt oil reservoir cannot be met. For a
hydrophobic associated polymer in which a small amount of
hydrophobic groups are introduced into molecular chains, the
solution of the hydrophobic associated polymer has efficient
viscosifying property, excellent salt resistance, and better
temperature resistance and shear resistance, and has a favorable
application prospect in enhanced oil recovery and acid fracturing
of an oil field.
[0004] The properties of a solution of a hydrophobic associated
polymer depend on the structure and property of a hydrophobic
monomer to a certain degree. The differences in the structure and
variety of hydrophobic monomers can greatly affect the properties
of the polymer. Hydrophobic monomers that have been reported so far
include (methyl) acrylate monomer, styrene monomer, (methyl)
acrylamide monomer, allyl monomer, and the like. Acrylate-type
hydrophobic monomers, which are extremely sensitive to temperature
and pH, can easily lead to the decrease of the viscosity of the
polymer solution because of the loss of the association effect of
the polymer (Huang Xuehong et al., Study on Properties of
Water-soluble Hydrophobic Associated Poly(Acrylamide-Hexadecyl
Acrylate). Journal of Functional Polymers, 2002, 14(1):90-94).
Although the styrene-type hydrophobic monomer has a rigid benzene
ring and can effectively improve the temperature resistance and
hydrolysis resistance of the polymer, the benzene ring is too close
to a molecular main chain, which is not conducive to the
copolymerization of the hydrophobic monomer and acrylamide, and
also not conducive to improve the viscosifying effect of the
polymer solution (Zhong Chuanyong, Characterization and Heat
Resistance of AM-STD-NaAMPS Ternary Hydrophobic Associated
Copolymer. Polymer Materials Science and Engineering, 2003, 19 (6):
126-130). The allyl type hydrophobic monomer, due to the presence
of allyl groups, is not easily copolymerized with main monomer
acrylamide, and the prepared hydrophobic associated polymer has a
low molecular weight and an unobvious viscosifying effect (Luo Shan
et al., Synthesis and Solution Property of Imidazoline-structured
Hydrophobic Associated Polymer. Chemical Research and Application,
2015, 27(8):1151-1156). Theacrylamide-type hydrophobic monomer
whose structure is similar to acrylamide is conducive to a
polymerization reaction, but there is a shortcoming of poor
resistance to hydrolysis. (Geng Tongmou, Viscosity Behavior of
Aqueous Solution of Hydrophobic Associated Water Soluble Polymer
P(AM/NaAA/DiAC16). Fine Chemicals, 2007, 24(9): 914-918).
[0005] Compared with a single-tailed hydrophobic monomer, a
double-tail hydrophobic monomer containing a benzene ring and a
long-chain alkyl group (Wu Xiaoyan et al. A Surface-active
Two-tailed Hydrophobic Associated Acrylamide Copolymer. Guangdong
Chemical Industry, 2014, 41(22): 42-44; Jiang Feng et al. Synthesis
and characterization of Two-tailed Acrylamide Hydrophobic
Associated Copolymers. Journal of Chemical Industry, 2015,
66(3):1215-1220) has the following advantages: by the introduction
of the benzene ring, the temperature resistance and hydrolysis
resistance of the polymer are effectively improved; by the
introduction of the long-chain alkyl group, the hydrophobic
association effect of the polymer is improved favorably; a main
structure of (methyl) acrylamides is adopted to make the
hydrophobic monomer easy to polymerize with acrylamide; the
two-tailed structure is conductive to improve the hydrolysis
resistance and hydrophobic association effect of the hydrophobic
monomer. Therefore, the hydrophobic monomer integrates the
advantages of various types of hydrophobic monomers, and can more
significantly improve the hydrophobic association effect of the
polymer, so that the synthesized hydrophobic associated polymer
achieves the purposes of temperature resistance and salt
resistance.
[0006] For a polymer containing polyoxyethylene ether side chains
(L'alloret F et al. Aqueous solution behavior of new
thermoassociative polymers. Colloid & Polymer Science, 1995,
273(12): 1163-1173; Yang Mingzhu et al. Study on Properties of
Novel Thermosensitive Modified Acrylamide Copolymer. Plastics
Industry, 2012, 40(4):35-38), a polyoxyethylene ether chain in the
molecule and a water molecule form a hydrogen bond. As the
temperature of the solution rises, the effect of the hydrogen bond
gradually weakens or the hydrogen bond is broken, the
hydrophilicity of the polyoxyethylene ether chain decreases, and
the hydrophobicity increases, thereby allowing the polymer to
exhibit a favorable thermal thickening effect within a higher
temperature range, and show higher apparent viscosity in a salt
solution.
SUMMARY
[0007] An objective of the present invention is to provide a
surface-active two-tailed hydrophobic associated polymer which
integrates the advantages of a double-tail hydrophobic associated
polymer and the advantages of a polymer containing a
polyoxyethylene ether side chain, such that the viscosifying
property, the temperature resistance, the salt resistance and the
hydrolysis resistance of the hydrophobic associated polymer are
remarkably improved, and overcomes the defects and deficiencies of
the prior art.
[0008] Another objective of the present invention is to provide a
preparation method of the surface-active two-tailed hydrophobic
associated polymer. The preparation method is reliable in principle
and simple and convenient in operation. The synthesized polymer can
be widely used as an oil-displacing agent or an acid fracturing
thickener for increasing a crude oil recovery rate in oilfield
development and has a broad market application prospect.
[0009] To fulfill said technical objectives, the present invention
adopts the following technical solution.
[0010] A surface-active two-tailed hydrophobic associated polymer
has the following structural formula:
##STR00001##
[0011] in the formula, x, y, z, m, and n are percentages of
structural units, where x is 75 to 85%, y is 10 to 20%, z is 0 to
5%, m is 0.1 to 0.2%, n is 0.2 to 0.5%, and x+y+z+m+n is 1; a, b
and c are numbers of structural units, wherein a is 7, 9, 11, 13 or
15, b is 1 or 2, and c is 5, 7, 10, 23 or 40; R.sub.1 and R.sub.2
are CH.sub.3 or H.
[0012] The polymer has a viscosity average molecular weight of 100
to 10,000,000.
[0013] The surface-active two-tailed hydrophobic associated polymer
is prepared using a micellar free radical copolymerization method
comprising: adding a surfactant sodium lauryl sulfate and a
hydrophobic monomer N-phenethyl-N-alkyl (methyl) acrylamide or
N-benzyl-N-alkyl (methyl) acrylamide into an aqueous solution
containing acrylamide, acrylic acid,
2-acrylamide-2-methylpropanesulfonic acid, and surface-active
macromonomer polyoxyethylene lauryl ether (methyl) acrylate,
wherein the surfactant is used to solubilize the hydrophobic
monomer in the formed micelle; adjusting pH to 6-8 with sodium
hydroxide; and copolymerizing the hydrophobic monomer and a
water-soluble monomer by means of photoinitiation to obtain the
surface-active two-tailed hydrophobic associated polymer. The
reaction principle is as follows:
##STR00002##
[0014] in the formula, x, y, z, m, and n are percentages of
structural units, where x is 75 to 85%, y is 10 to 20%, z is 0 to
5%, m is 0.1 to 0.2%, n is 0.2 to 0.5%, and x+y+z+m+n is 1; a, b
and c are numbers of structural units, wherein a is 7, 9, 11, 13 or
15, b is 1 or 2, and c is 5, 7, 10, 23 or 40; R.sub.1 and R.sub.2
are CH.sub.3 or H.
[0015] The polymer has a viscosity average molecular weight of 100
to 10,000,000.
[0016] A preparation process of the surface-active two-tailed
hydrophobic associated polymer comprises the following steps:
[0017] (1) adding acrylamide, acrylic acid,
2-acrylamide-2-methylpropanesulfonic acid, and surface-active
macromonomer polyoxyethylene lauryl ether (methyl) acrylate to
distilled water, stirring uniformly, adjusting pH of the solution
to 6-8 with sodium hydroxide, adding a hydrophobic monomer
N-phenethyl-N-alkyl (methyl) acrylamide or N-benzyl-N-alkyl
(methyl) acrylamide and a surfactant sodium lauryl sulfate, and
stirring till the solution is clear and transparent, wherein the
total mass percentage of reaction monomers is 25 to 30 wt %, in
which acrylamide accounts for 20 to 21.5 wt %, acrylic acid
accounts for 3.5 to 5 wt %, 2-acrylamide-2-methylpropanesulfonic
acid accounts for 0 to 2 wt %, polyoxyethylene lauryl ether
(methyl) acrylate accounts for 0.2 to 0.6 wt %, N-phenethyl-N-alkyl
(methyl) acrylamide or N-benzyl-N-alkyl (methyl) acrylamide
accounts for 0.2 to 0.6 wt %, and sodium lauryl sulfate accounts
for 0.8 to 2.0 wt %;
[0018] (2) introducing nitrogen for 15 min to remove dissolved
oxygen in water; and
[0019] (3) adding a photoinitiator and reacting for 3 to 5 h at 10
to 30.degree. C. under a photoinitiation device to obtain viscous
white colloid, i.e., the surface-active two-tailed hydrophobic
associated polymer.
[0020] The photoinitiator is azobis (isobutylamidine hydrochloride)
(v50) or 2-hydroxyl-4'-(2-hydroxyethoxy)-2-methylpropiophenone
(Irgacure 2959).
[0021] Compared with the prior art, the present invention has the
following beneficial effects: (1) the hydrophobic monomer with an
acrylamide structure is easily copolymerized with water-soluble
monomers, such as acrylamide; because the hydrophobic chain of the
hydrophobic monomer has a benzene ring structure, the hydrolysis of
amide groups can be effectively inhibited, and meanwhile the
rigidity of molecular chains can be increased and the temperature
resistance of the polymer can be improved; because the hydrophobic
chain of the hydrophobic monomer contains a long-chain alkyl group,
the hydrophobic association effect is achieved; the double-tail
structure of the hydrophobic monomer can effectively inhibit the
hydrolysis of amide groups and improve the hydrophobic association
effect. Therefore, the hydrophobic associated polymer has better
viscosifying property, and resistance to temperature and salt;
[0022] (2) by the introduction of surface-active macromonomers
containing polyoxyethylene ether and long-chain alkyl groups into
polymer molecular chains, the polymer has the properties of the
surfactant, and the properties of the hydrophobic associated
polymer, such as viscosifying property, temperature resistance,
salt resistance, and hydrolysis resistance, can be significantly
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is an infrared spectrum of a surface-active
two-tailed hydrophobic associated polymer.
[0024] FIG. 2 is a viscosity-concentration relationship curve of
the surface-active two-tailed hydrophobic associated polymer.
[0025] FIG. 3 is a viscosity-NaCl concentration relationship curve
of the surface-active two-tailed hydrophobic associated
polymer.
[0026] FIG. 4 is a viscosity-CaCl.sub.2 concentration relationship
curve of the surface-active two-tailed hydrophobic associated
polymer.
[0027] FIG. 5 is a viscosity-aging days relationship curve of the
surface-active two-tailed hydrophobic associated polymer.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] The present invention is described below in detail according
to the drawings and the--examples.
[0029] I. Preparation of Surface-Active Two-Tailed Hydrophobic
Associated Polymer
Example 1
[0030] Weighing acrylamide (10 g), acrylic acid (2.5 g) and
surface-active macromonomer polyoxyethylene lauryl ether (methyl)
acrylate (0.1 g), adding distilled water and stirring uniformly,
and adjusting pH to 7; then, adding N-phenethyl-N-lauryl
methacrylamide (0.1 g) and sodium lauryl sulfate (0.3 g), then
adding a certain amount of distilled water such that the total mass
of the solution reaches 50 g, and stirring till the solution is
clear and transparent; introducing nitrogen for 15 min to remove
dissolved oxygen in water; and adding an initiator v50 (0.016 wt %
of total monomer mass), placing under a photoinitiation device, and
reacting for 4 h.
Example 2
[0031] Weighing acrylamide (9.9 g), acrylic acid (1.6 g),
2-acrylamide-2-methylpropanesulfonic acid (1.0 g) and
surface-active macromonomer polyoxyethylene lauryl ether (methyl)
acrylate (0.3 g), adding distilled water and stirring uniformly,
and adjusting pH to 7; then, adding N-benzyl-N-lauryl
methacrylamide (0.3 g) and sodium lauryl sulfate (0.7), then adding
a certain amount of distilled water such that the total mass of the
solution reaches 50 g, and stirring till the solution is clear and
transparent; introducing nitrogen for 15 min to remove dissolved
oxygen in water; and adding an initiator v50 (0.1 wt % of total
monomer mass), placing under a photoinitiation device, and reacting
for 4 h.
Example 3
[0032] Weighing acrylamide (9.9 g), acrylic acid (1.6 g),
2-acrylamide-2-methylpropanesulfonic acid (1.0 g) and
surface-active macromonomer polyoxyethylene lauryl ether (methyl)
acrylate (0.3 g), adding distilled water and stirring uniformly,
and adjusting pH to 7; then, adding N-phenethyl-N-lauryl
methacrylamide (0.3 g) and sodium lauryl sulfate (0.7 g), then
adding a certain amount of distilled water such that the total mass
of the solution reaches 50 g, and stirring till the solution is
clear and transparent; introducing nitrogen for 15 min to remove
dissolved oxygen in water; and adding an initiator V50 (0.016 wt %
of total monomer mass), placing under a photoinitiation device, and
reacting for 4 h.
Example 4
[0033] Weighing acrylamide (10 g), acrylic acid (2.5 g) and
surface-active macromonomer polyoxyethylene lauryl ether (methyl)
acrylate (0.3 g), adding distilled water and stirring uniformly,
and adjusting pH to 7; then, adding N-phenethyl-N-tetradecyl
methacrylamide (0.3 g) and sodium lauryl sulfate (0.7 g), then
adding a certain amount of distilled water such that the total mass
of the solution reaches 50 g, and stirring till the solution is
clear and transparent; introducing nitrogen for 15 min to remove
dissolved oxygen in water; and adding an initiator Irgacure2959
(0.016 wt % of total monomer mass), placing under a photoinitiation
device, and reacting for 4 h.
[0034] II. Structural Characterization of Surface-Active Two-Tailed
Hydrophobic Associated Polymer
[0035] FIG. 1 is an infrared spectrum of the hydrophobic associated
polymer synthesized in the example 1.
[0036] As can be seen from FIG. 1, a stretching vibration
absorption peak of N--H of primary amide appears at 3408 cm.sup.-1;
a vibration absorption peak of methylene appears at 2926 cm.sup.-1;
a bending vibration absorption peak of primary amide N--H appears
at 1639 cm.sup.-1; a characteristic absorption peak of carbonyl
appears at 1670 cm.sup.-1; a stretching vibration peak of a benzene
ring skeleton appears at 1530 cm.sup.-1; an in-plane bending
vibration absorption peak of methylene appears at 1398 cm.sup.-1; a
stretching vibration peak of ethyoxyl appears at 1057 cm.sup.-1; an
out-of-plane rocking characteristic peak of primary amide-NH.sub.2
appears at 630 cm.sup.-1.
[0037] III. Viscosifying Effect Analysis of Surface-Active
Two-Tailed Hydrophobic Associated Polymer
[0038] The polymer synthesized in the example 1 is prepared into
polymer solutions of different concentrations. A
viscosity-concentration relationship curve of the polymer is
measured at room temperature and at a shear rate of 7.34 s.sup.-1
(as shown in FIG. 2).
[0039] As can be seen from FIG. 2, the polymer has a strong
hydrophobic association effect and a significant viscosifying
effect. The viscosity of the polymer solution at 1000 mg/L reaches
300 mPas, and the viscosity of the polymer solution at 2000 mg/L
reaches 753.4 mPas.
[0040] IV. Sensitivity to Salt of Surface-Active Two-Tailed
Hydrophobic Associated Polymer
[0041] A study is made for the sensitivity to salt of the polymer
synthesized in the example 1. The prepared hydrophobic associated
polymer is prepared into a 1000 mg/L polymer solution under
different salinities. A change relationship of the apparent
viscosity of the polymer solution along with the salinity is
measured at room temperature and at a shear rate of 7.34 s.sup.-1
(as shown in FIG. 3 and FIG. 4).
[0042] As can be seen from FIG. 3 and FIG. 4, with the increase of
the salinity, the apparent viscosity of the polymer presents a
trend of decrease-increase-decrease, with a wider salt thickening
area. Moreover, the viscosity of the polymer solution can be
maintained at 10% or more under high salinity 200,000 of NaCl and
10,000 of CaCl.sub.2), showing a very good salt resistance
effect.
[0043] V. Anti-Aging Property of Surface-Active Two-Tailed
Hydrophobic Associated Polymer
[0044] The anti-aging property of the polymer synthesized in the
example 1 is evaluated. The prepared hydrophobic associated polymer
is prepared into a 1000 mg/L polymer solution, deoxidant is added
to the solution and then the mixture is placed in a vial, and
sealed. The mixture is aged in a 90.degree. C. oven, and the
viscosity of the polymer solution is measured at regular time.
[0045] As can be seen from FIG. 5, the viscosity is basically
stable after the polymer solution is aged for about 25 d. At a
temperature of 90.degree. C. and a salinity of 10.times.10.sup.4
mg/L, the viscosity of the polymer solution can still be maintained
at 30 mPas or more, showing good resistance to temperature, salt
and aging.
* * * * *