CN109232802B

CN109232802B - Acrylamide copolymer and preparation method and application thereof

Info

Publication number: CN109232802B
Application number: CN201710556406.1A
Authority: CN
Inventors: 张文龙; 伊卓; 祝纶宇; 刘希
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2017-07-10
Filing date: 2017-07-10
Publication date: 2020-12-18
Anticipated expiration: 2037-07-10
Also published as: CN109232802A

Abstract

The invention relates to the field of oilfield chemicals, and discloses an acrylamide copolymer and a preparation method and application thereof, wherein the acrylamide copolymer comprises a structural unit A and a structural unit B, wherein the structural unit A is a structural unit shown in a formula (I), and the structural unit B is a structural unit shown in a formula (II); and the content of the structural unit A is 95-99.9 wt% and the content of the structural unit B is 0.1-5 wt% based on the total weight of the acrylamide copolymer. The acrylamide copolymer can be used as a thermal thickener for tertiary oil recovery of high-temperature and high-salinity oil reservoirs.

Description

Acrylamide copolymer and preparation method and application thereof

Technical Field

The invention relates to the field of oilfield chemicals, and particularly relates to an acrylamide copolymer and a preparation method and application thereof.

Background

The polymer flooding technology is an important technology for increasing the recovery rate of petroleum, and the basic principle is that a water-soluble polymer is added into water injection to increase the viscosity of an aqueous solution, reduce the water/oil fluidity ratio, enlarge the swept volume, increase the swept efficiency and reduce the oil saturation of the swept zone, thereby increasing the recovery rate of petroleum. Practice proves that the oil recovery rate can be greatly improved by adopting the polymer for oil displacement, and great economic benefit and social benefit are generated. For many years, the polymers used for polymer flooding were mainly artificially synthesized partially hydrolyzed polyacrylamides. The limitation of the common partially hydrolyzed polyacrylamide is that the temperature resistance and salt tolerance are low, and the viscosity of the aqueous solution is greatly reduced under the conditions of high temperature and high salinity, thereby obviously influencing the oil displacement effect.

In order to develop a polymer oil displacement agent with better performance and capable of meeting the use requirement of tertiary oil recovery in a high-temperature oil field (the temperature is higher than 85 ℃), Chinese patent CN1240795A discloses a temperature-resistant salt-resistant copolymer thickening agent, which is a copolymer formed by copolymerizing an initiator, a monomer (A) and a monomer (B), and is characterized in that the monomer (A) is one or more water-soluble unsaturated monomers with olefinic chains, such as acrylamides, vinyl pyrrolidone, 2-acrylamide-2-methyl propanesulfonic acid and acrylic acid, and the monomer (B) is a paste obtained by mixing, heating and refluxing (polyoxyethylene) n-alkanol ether, toluene, maleic acid and p-toluenesulfonic acid, and removing excessive water and residual toluene by azeotropy; the copolymer is characterized in that molecules contain amphiphilic macromonomer chain links, and the temperature resistance of the copolymer is better than that of common partially hydrolyzed polyacrylamide, but amphiphilic branched chains in the copolymer are connected with a main chain through ester bonds, and the ester bonds are easy to hydrolyze at high temperature, so that the stability of the polymer is influenced. Chinese patents CN1317501A, CN1414057A, CN1876751A and the like invented oil displacement agents of hydrophobic association polymers with different molecular structures, and the polymers are characterized in that a molecular main chain contains a certain number of hydrophobic molecular chain segments, and in an aqueous solution, the hydrophobic-hydrophobic interaction between hydrophobic side chains causes physical crosslinking among the polymer molecular chains, so that the viscosity and the anti-shearing performance of the solution are improved. However, the difficulty of forming effective hydrophobic associative thickening at lower polymer concentrations is not significant.

Thermo-thickening polymers are a class of polymers whose aqueous solution viscosity increases with increasing temperature over a range of temperatures. Chinese patent CN101302267A (200810095791.5) discloses a nonionic thermal tackifying water soluble polymer, which is a polymer formed by copolymerizing a monomer (A) and a monomer (B), and is characterized in that the monomer (A) is a nonionic monomer, and the monomer (B) is a nonionic macromonomer without surface activity; by adopting a molecular design method of the thermal tackifying water-soluble polymer and utilizing the copolymerization of the nonionic water-soluble macromonomer and the nonionic monomer acrylamide, the water solubility of the copolymer can be increased, and the viscosity of the copolymer can be obviously increased along with the increase of the temperature; however, as can be seen from fig. 1 and 2 of the patent, thickening is already evident at lower temperatures, which is detrimental to the migratory motion of the polymer in the formation.

Therefore, how to improve the stability of acrylamide copolymers, the thickening effect, especially at low temperature, remains a problem to be solved urgently.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide an acrylamide copolymer and a preparation method and application thereof.

In order to achieve the above object, an aspect of the present invention provides an acrylamide copolymer, wherein the acrylamide copolymer comprises a structural unit a and a structural unit B, wherein the structural unit a is a structural unit represented by formula (I), and the structural unit B is a structural unit represented by formula (II); based on the total weight of the acrylamide copolymer, the content of the structural unit A is 95-99.9 wt%, and the content of the structural unit B is 0.1-5 wt%;

wherein R is₁And R₂Each independently is hydrogen or C1-C4 alkyl, R₃Is C1-C12 alkylene, R₄、R₅、R₆And R₇Each independently hydrogen or C1-C12 alkyl.

Preferably, the content of the structural unit A is 96 to 99.7 wt% and the content of the structural unit B is 0.3 to 4 wt% based on the total weight of the acrylamide copolymer.

Preferably, the viscosity average molecular weight of the acrylamide copolymer is 1400 to 1800 ten thousand; more preferably, the acrylamide copolymer has a viscosity average molecular weight of 1350 to 1700 ten thousand.

Preferably, R₁And R₂Each independently is H or methyl, R₃Is C2-C6 alkylene, R₄、 R₅、R₆And R₇Each independently is H or C1-C6 alkyl.

The invention also provides a preparation method of the acrylamide copolymer, wherein the preparation method comprises the steps of carrying out polymerization reaction on a monomer mixture in water under the condition of solution polymerization reaction of olefin and in the presence of an initiator to obtain the acrylamide copolymer; the monomer mixture contains a monomer C and a monomer D, wherein the monomer C is a monomer with a structure shown in a formula (III), and the monomer D is a monomer with a structure shown in a formula (IV); and the weight ratio of the monomer C to the monomer D is 1: (0.001-0.05);

wherein R is₁' and R₂' independently of one another are hydrogen or C1-C4 alkyl, R₃' is C1-C12 alkylene, R₄′、R₅′、R₆' and R₇' are each independently hydrogen or C1-C12 alkyl.

Preferably, the monomer C is used in an amount of 100-450 parts by weight and the monomer D is used in an amount of 0.18-15 parts by weight, based on 1000 parts by weight of water; preferably, the monomer C is used in an amount of 180-260 parts by weight, and the monomer E is used in an amount of 0.36-6 parts by weight.

Preferably, the initiator is selected from azo-based initiators and redox-based initiators, the azo-based initiator being used in an amount of 0.0002 to 0.05 wt%, preferably 0.0018 to 0.018 wt%, based on the total weight of the monomers in the monomer mixture; the redox initiator is used in an amount of 0.0002 to 0.05 wt%, preferably 0.0018 to 0.018 wt% based on the total weight of the monomers in the monomer mixture; the redox initiator comprises an oxidizing agent and a reducing agent, wherein the reducing agent is an inorganic reducing agent and/or an organic reducing agent, and the weight ratio of the oxidizing agent to the reducing agent is (0.1-1): 1;

preferably, the azo-based initiator is a water-soluble azo-based initiator selected from at least one of 2,2 ' -azobisisobutyronitrile, 2 ' -azobisisobutylamidine dihydrochloride, azobisisoheptonitrile, 2 ' -azobis (2-methylpropionamidine) hydrochloride, 2 ' -azo [2- (2-imidazolin-2-yl) propane ] dihydrochloride, and 4,4 ' -azobis (4-cyanovaleric acid);

preferably, the oxidizing agent is at least one of benzoyl peroxide, hydrogen peroxide, t-butyl hydroperoxide, 2, 5-dimethyl-2, 5 bis (hydroperoxy) hexane, ammonium persulfate, sodium persulfate, and potassium persulfate; the inorganic reducing agent is at least one of ferrous sulfate, ammonium ferrous sulfate, cuprous chloride, potassium sulfite, sodium sulfite, ammonium bisulfite, potassium bisulfite, sodium thiosulfate, potassium thiosulfate, rongalite and sodium bisulfite; the organic reducing agent is at least one of N, N-dimethylethanolamine, N, N-dimethylpiperazine, tetramethylurea, N, N-dimethylethylenediamine and N, N, N ', N' -tetramethylethylenediamine.

Preferably, the monomer C is an acrylamide monomer, and the acrylamide monomer is one or more of acrylamide, methacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-isopropylacrylamide, N-methylolacrylamide and N-hydroxyethyl acrylamide;

preferably, the monomer D is represented by the formula (IV), wherein R₂' is H, R₃' is C2-C6 alkylene, R₄′、R₅′、R₆' and R₇' are each independently H or C1-C6 alkyl.

Preferably, the solution polymerization conditions of the olefin comprise: the solution polymerization reaction of the olefin is carried out in an inert atmosphere, the initiator is an azo initiator, the temperature is 40-70 ℃, the time is 2-10h, and the pH value is 6-8.

Preferably, the solution polymerization conditions of the olefin comprise: the solution polymerization reaction of the olefin is carried out in an inert atmosphere, the initiator is a redox initiator, the temperature is 15-30 ℃, the time is 5-10h, and the pH value is 6-8.

Preferably, the method further comprises drying the polymer obtained after the polymerization reaction, wherein the drying conditions comprise: the temperature is 40-120 ℃ and the time is 0.2-4 hours.

The invention also provides the application of the acrylamide copolymer prepared by the method as a thermal thickener.

According to the acrylamide copolymer provided by the invention, a borate structural unit C with hydrophobic property shown in a formula (II) is introduced, and the acrylamide copolymer forms a large space network structure formed by association among polymer molecules by utilizing hydrophobic effect, namely a dynamic physical cross-linking network structure, so that the solution viscosity is obviously increased compared with that of the acrylamide polymer; in addition, under the condition of formation temperature (70-95 ℃), part of acrylamide units are hydrolyzed to generate acrylic acid, part of borate ester structures in the structural units B are hydrolyzed to generate new hydroxyl groups, and the new hydroxyl groups and carboxyl groups are generated, so that the hydration radius of the acrylamide copolymer is increased, and the viscosity of the acrylamide copolymer aqueous solution is further increased; on the other hand, the intermolecular hydroxyl and carboxyl can generate micro-crosslinking reaction at high temperature, so that the viscosity of the acrylamide copolymer aqueous solution is further improved, and the purpose of thickening is achieved.

In addition, under the high temperature condition of 85-95 ℃, the apparent viscosity of the aqueous solution of the acrylamide copolymer provided by the invention can reach more than 18mPa.s, so that the acrylamide copolymer has the advantage of great thickening, and the acrylamide copolymer provided by the invention can be used as a thickening agent, so that the thermal thickening agent has the advantages of stable structure and higher viscosity at normal temperature, does not reduce the viscosity at high temperature (higher than 85 ℃), has a certain increase, has the effects of reducing the water/oil flow ratio and improving the oil recovery ratio, and can be used as a thermal thickening agent for tertiary oil recovery at high temperature and high salinity.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides an acrylamide copolymer, which comprises a structural unit A and a structural unit B, wherein the structural unit A is a structural unit shown in a formula (I), and the structural unit B is a structural unit shown in a formula (II); based on the total weight of the acrylamide copolymer, the content of the structural unit A is 95-99.9 wt%, and the content of the structural unit B is 0.1-5 wt%;

wherein R is₁、R₂Each independently is hydrogen or C1-C4 alkyl, R₃May be C1-C12 alkylene, R₄、R₅、R₆、R₇May each independently be hydrogen or C1-C12An alkyl group.

According to the present invention, the object of the present invention can be achieved to some extent by the acrylamide copolymer which contains the structural unit A and the structural unit B and satisfies the above ratio.

In the present invention, the alkyl group having 1 to 4 may be a straight chain or a branched chain. Examples of the C1-C4 alkyl group may include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl.

In the present invention, the alkyl group having 1-12 carbon atoms may be linear or branched. Examples of the C1-C12 alkyl group may include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl and n-dodecyl.

The inventors of the present invention found out in their research that a polymer composed of specific structural units a and B can achieve a good thickening effect when used in a thermal thickener. For example, R in the structural unit A represented by the formula (I)₁Is H or methyl, R in the structural unit B represented by the formula (II)₂Is H or methyl, R₃Is any one of alkylene of C2-C6, R₄、R₅、R₆And R₇Each independently is H or any one of alkyl of C1-C6, wherein R₄、R₅、R₆And R₇May be the same or different.

In the present invention, although the object of the present invention can be achieved as long as it contains the structural unit A and the structural unit B and satisfies the above proportional relationship, it is preferable that the content of the structural unit A is 95 to 99.9% by weight and the content of the structural unit B is 0.1 to 5% by weight, based on the total weight of the acrylamide copolymer; more preferably, the content of the structural unit a is 96 to 99.7% by weight and the content of the structural unit B is 0.3 to 4% by weight, based on the total weight of the acrylamide copolymer.

In the present invention, the viscosity average molecular weight of the acrylamide copolymer is 1400 to 1800 ten thousand; preferably, the viscosity average molecular weight of the acrylamide copolymer is 1350 to 1700 ten thousand.

In addition, the invention also provides a preparation method of the acrylamide copolymer, wherein the preparation method comprises the steps of carrying out polymerization reaction on a monomer mixture in water under the condition of solution polymerization reaction of olefin and in the presence of an initiator to obtain the acrylamide copolymer; the monomer mixture contains a monomer C and a monomer D, wherein the monomer C is a monomer with a structure shown in a formula (III), and the monomer D is a monomer with a structure shown in a formula (IV); and the weight ratio of the monomer C to the monomer D is 1: (0.001-0.05);

According to the preparation method of the present invention, the object of the present invention can be achieved to some extent by the acrylamide copolymer prepared by copolymerizing the monomer C and the monomer D in the above-mentioned ratio. Preferably, the weight ratio of the monomer C to the monomer D is 1: (0.002-0.02).

According to the production method of the present invention, it is preferable that the polymerization reaction is a random copolymerization reaction.

The preparation method according to the present invention, wherein the monomer C having the structure represented by formula (III) may be an acrylamide-based monomer, and examples that may be used include, but are not limited to, one or more of acrylamide, methacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-isopropylacrylamide, N-methylolacrylamide, and N-hydroxyethylacrylamide; preferably, the monomer D is acrylamide or methacrylamide.

According to the preparation method of the invention, the monomer D with the structure shown in the formula (IV) can be simply called as a boron-containing monomer, and R in the formula (IV) is preferably selected₂' is H, R₃' is any one of alkylene of C2-C6, R₄′、R₅′、R₆' and R₇' are each independently any of H or C1-C6 alkyl.

According to the production method of the present invention, by selecting a specific monomer C and a specific structural monomer D to react, the thickening effect of the resulting polymer can be further improved.

According to the preparation method of the present invention, the solution polymerization reaction is carried out in water, and the ratio of the weight of the monomer mixture to the total weight of water and the monomer mixture at the start of the solution polymerization reaction of the olefin is not particularly limited and may be varied within a wide range as long as the monomer mixture can be dissolved in water to facilitate the solution polymerization reaction, and preferably, the water is deionized water. Preferably, the monomer C is used in an amount of 100-450 parts by weight, preferably 180-260 parts by weight, based on 1000 parts by weight of water. The amount of the monomer D is 0.18 to 15 parts by weight, preferably 0.36 to 6 parts by weight, calculated according to the weight ratio of the monomer C to the monomer D, which corresponds to 1000 parts by weight of the monomer C added.

According to the preparation method of the present invention, there is no particular requirement for the selection of the initiator as long as it can promote the solution polymerization of the olefin in the monomer C and the monomer D, and examples thereof include, but are not limited to, azo-based initiators or redox-based initiators; wherein, the azo initiator can be used in an amount of 0.0002 to 0.05 wt%, preferably 0.0018 to 0.018 wt% of the total weight of the monomers in the monomer mixture; the redox initiator may be used in an amount of 0.0002 to 0.05 wt%, preferably 0.0018 to 0.018 wt% based on the total weight of the monomers in the monomer mixture; the redox initiator includes an oxidizing agent and a reducing agent, the reducing agent is an inorganic reducing agent and/or an organic reducing agent, and the weight ratio of the oxidizing agent to the reducing agent may be (0.1-1): 1;

preferably, the azo-based initiator is a water-soluble azo-based initiator selected from at least one of 2,2 ' -azobisisobutyronitrile, 2 ' -azobisisobutylamidine dihydrochloride, azobisisoheptonitrile, 2 ' -azobis (2-methylpropionamidine) hydrochloride, 2 ' -azo [2- (2-imidazolin-2-yl) propane ] dihydrochloride, and 4,4 ' -azobis (4-cyanovaleric acid); more preferably, the water-soluble azo initiator is 2,2 '-azobisisobutylamidine dihydrochloride or 2, 2' -azobis (2-methylpropionamidine) hydrochloride;

preferably, the oxidizing agent is at least one of benzoyl peroxide, hydrogen peroxide, t-butyl hydroperoxide, 2, 5-dimethyl-2, 5 bis (hydroperoxy) hexane, ammonium persulfate, sodium persulfate, and potassium persulfate; more preferably, the oxidizing agent is ammonium sulfate, potassium persulfate, or ammonium persulfate;

preferably, the inorganic reducing agent is at least one of ferrous sulfate, ferrous ammonium sulfate, cuprous chloride, potassium sulfite, sodium sulfite, ammonium bisulfite, potassium bisulfite, sodium thiosulfate, potassium thiosulfate, rongalite and sodium bisulfite; the organic reducing agent is at least one of N, N-dimethylethanolamine, N, N-dimethylpiperazine, tetramethylurea, N, N-dimethylethylenediamine and N, N, N ', N' -tetramethylethylenediamine; more preferably, the reducing agent is sodium sulfite or sodium bisulfite.

According to the preparation method, no special requirements are required for the conditions of the solution polymerization reaction of the olefin, and the corresponding reaction conditions can be reasonably adjusted according to the applicable conditions of the selected initiator.

Preferably, the solution polymerization conditions of the olefin comprise: the solution polymerization reaction of the olefin is carried out in an inert atmosphere, the initiator is an azo initiator, and the temperature is 40-70 ℃, preferably 45-50 ℃; the time is 2 to 10 hours, preferably 4 to 6 hours; the pH value is 6-8, preferably 6.5-7.5.

Preferably, the solution polymerization conditions of the olefin comprise: the solution polymerization reaction of the olefin is carried out in an inert atmosphere, the initiator is a redox initiator, and the temperature is 15-30 ℃, preferably 15-20 ℃; the time is 5 to 10 hours, preferably 6 to 7 hours; the pH value is 6-8, preferably 6.5-7.5.

Preferably, the pH in the solution polymerization conditions of the olefin is adjusted by adding a base and/or an acid, the base may be an inorganic base or an organic amine compound, such as at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, aqueous ammonia, methylamine, ethylamine, ethanolamine and triethanolamine, and is preferably sodium hydroxide. The acid is preferably an inorganic acid, and the inorganic acid may be at least one of hydrochloric acid, sulfuric acid, sulfonic acid, nitric acid, and phosphoric acid.

Preferably, the inert atmosphere (also referred to as protective atmosphere) refers to an atmosphere in the presence of an inert gas (protective gas), wherein the inert gas (protective gas) is a gas that does not react with the raw materials and the products, and may be, for example, at least one of nitrogen gas or a gas of a group zero element (helium, neon, argon, krypton, xenon) in the periodic table of elements, which is conventional in the art; preferably, the inert gas is nitrogen.

According to the preparation method of the present invention, the inert atmosphere in the solution polymerization reaction conditions of the olefin is optionally realized by: continuously introducing inert gas in the process of the solution polymerization reaction of the olefin; or introducing inert gas into the aqueous solution mixed with the monomer mixture for a predetermined time before the solution polymerization of the olefin begins, and then sealing the solution polymerization space; preferably, the predetermined time is 20-40 min.

According to the preparation method, the acrylamide copolymer obtained after polymerization reaction is granulated, dried, crushed and screened. Wherein the drying step is not particularly required, and conventional methods known in the art can be adopted, for example, the drying method can be a hot air drying method, and the hot air drying temperature can be 40-120 ℃, preferably 70-90 ℃; the time is 0.2 to 4 hours, preferably 0.5 to 2 hours. The steps of granulation, pulverization and screening are not particularly required, and conventional methods known in the art can be adopted, and are not described in detail herein.

Meanwhile, the invention also provides an acrylamide copolymer prepared by the preparation method. The acrylamide copolymer has the same content of structural units as the acrylamide copolymer described above in the present invention, and will not be described herein again.

In addition, the invention also provides an application of the acrylamide copolymer as a thermal thickener. By adopting the acrylamide copolymer as the thickening agent, the high-temperature high-salinity oil reservoir tertiary oil recovery agent has the advantages of stable structure, high viscosity at normal temperature, no reduction of viscosity at high temperature (higher than 85 ℃), certain increase, reduction of water/oil flow ratio and improvement of oil recovery rate, and is suitable for tertiary oil recovery of high-temperature high-salinity oil reservoirs.

Hereinafter, a specific embodiment of the present invention will be described in detail by way of examples.

In the following examples, the performance test of the product was carried out using the following method:

1. viscosity average molecular weight: according to formula M_v＝([η]/K)^1\αCalculation was carried out where K ═ 4.5 × 10^-3α is 0.80, intrinsic viscosity [. eta. ]]According toThe intrinsic viscosity of the polyacrylamide is measured by a measuring method of GB 12005.1-1989;

2. polymer dissolution time: the measurement was carried out according to the method specified in the Petroleum administration for victory enterprises Standard Q/SH 10201572-2006.

3. The apparent viscosities of the polymer solutions at different temperatures were measured using a rotational viscometer model DV-III ULTRA supplied by Bohler fly (Brookfield) USA.

The raw materials used in the following examples are illustrated below:

acrylamide is commercially available from momo biochemical industries, inc;

2,2 ' -azobis (2-methylpropionamidine) hydrochloride, 2 ' -azobisisobutylamidine dihydrochloride, and 4,4 ' -azobis (4-cyanovaleric acid) were all commercially available from Aldrich;

ammonium persulfate and sodium bisulfite are commercially available from Beijing Chemicals, Inc.

Preparation example 1

The structural monomer F of formula (VI) is prepared according to the preparation method of Acs Macro Letters, 2012,1(5): 529-:

that is, in the monomer F having a structure represented by the formula (VI), R₂' is H, R₃' is ethylene, R₄′、R₅′、 R₆' and R₇' are each independently methyl.

Example 1

This example illustrates the preparation of acrylamide copolymers according to the present invention.

(1) Random copolymerization reaction: 240g of acrylamide (AM, monomer C) and 1.2g of the boron-containing monomer (monomer D) prepared in preparation example 1 above and 1000g of deionized water were added to a beaker at room temperature with stirring; after the raw materials are dissolved, adding sodium hydroxide into the aqueous solution to adjust the pH value of the aqueous solution to 7.5; then introducing nitrogen into the aqueous solution to remove oxygen for 30min, and sealing the beaker to form inert atmosphere; then 0.01g of ammonium persulfate and 0.01g of sodium bisulfite are added into the aqueous solution to be used as a redox initiation system, and then the mixture reacts for 7 hours at the constant temperature of 15 ℃ under normal pressure to obtain a colloidal polymer solution product;

(2) granulating, drying, crushing and screening: the gel-like polymer solution product was pelletized by a pelletizer into copolymer pellets of 4 to 6 mm, dried at 80 ℃ for 1 hour, and then sieved by pulverization to obtain an acrylamide copolymer product P1 of 20 to 80 mesh.

As a result, it was found that the viscosity-average molecular weight of the acrylamide copolymer product P1 was 1700X 10⁴The dissolving time is 90 min; and

according to the calculation of the charging amount, the structural unit A (wherein R is the total weight of the acrylamide copolymer product P1)₁Is H) in an amount of 99.5% by weight, structural unit B (wherein R is₂Is H, R₃Is ethylene, R₄、R₅、R₆And R₇Methyl) was contained in the amount of 0.5 wt%.

Example 2

(1) Random copolymerization reaction: 180g of acrylamide (AM, monomer C) and 0.36g of the boron-containing monomer prepared in preparation example 1 above (monomer F) and 1000g of deionized water were added to a beaker at room temperature with stirring; after the raw materials are dissolved, adding sodium hydroxide into the aqueous solution to adjust the pH of the aqueous solution to 6.5; then introducing nitrogen into the aqueous solution to remove oxygen for 30min, and sealing the beaker to form inert atmosphere; then adding 0.02g of initiator 2, 2' -azobis (2-methyl propionamidine) hydrochloride (AIBA) into the aqueous solution, and reacting for 4 hours at constant temperature of 50 ℃ under normal pressure (water bath temperature control) to obtain a colloidal polymer solution product;

(2) granulating, drying, crushing and screening: the gel-like polymer solution product was pelletized by a pelletizer into copolymer pellets of 4 to 6 mm, dried at 80 ℃ for 1 hour, and then sieved by pulverization to obtain an acrylamide copolymer product P2 of 20 to 80 mesh.

The result is measuredThe viscosity-average molecular weight of the acrylamide copolymer product P2 was 1620X 10⁴The dissolving time is 85 min; and

according to the calculation of the charging amount, the structural unit A (wherein R is the total weight of the acrylamide copolymer product P2)₁Is H) in an amount of 99.8% by weight, structural unit B (wherein R is₂Is H, R₃Is ethylene, R₄、R₅、R₆And R₇Methyl) was contained in the amount of 0.2 wt%.

Example 3

(1) Random copolymerization reaction: 300g of acrylamide (AM, monomer C) and 6g of the boron-containing monomer (monomer D) prepared in the above preparation example 1 and 1000g of deionized water were added to a beaker at room temperature with stirring; after the raw materials are dissolved, adding sodium hydroxide into the aqueous solution to adjust the pH value of the aqueous solution to 7; then introducing nitrogen into the aqueous solution to remove oxygen for 30min, and sealing the beaker to form inert atmosphere; then 0.015g of initiator 2, 2' -azobisisobutylamidine dihydrochloride is added into the aqueous solution, and then the reaction is carried out for 6 hours at the constant temperature of 45 ℃ under the normal pressure, so as to obtain a colloidal polymer solution product;

(2) granulating, drying, crushing and screening: the gel-like polymer solution product was pelletized by a pelletizer into copolymer pellets of 4 to 6 mm, dried at 80 ℃ for 1 hour, and then sieved by pulverization to obtain an acrylamide copolymer product P3 of 20 to 80 mesh.

As a result, it was found that the viscosity-average molecular weight of the acrylamide copolymer product P3 was 1600X 10⁴The dissolving time is 98 min; and

according to the calculation of the charging amount, the structural unit A (wherein R is the total weight of the acrylamide copolymer product P3)₁H) in an amount of 98 wt.%, structural unit B (wherein R is₂Is H, R₃Is ethylene, R₄、R₅、R₆And R₇Methyl) was contained in an amount of 2% by weight.

Example 4

(1) Random copolymerization reaction: 240g of acrylamide (AM, monomer C) and 9g of the boron-containing monomer (monomer D) prepared in the above preparation example 1 and 1000g of deionized water were added to a beaker at room temperature under stirring; after the raw materials are dissolved, adding sodium hydroxide into the aqueous solution to adjust the pH value of the aqueous solution to 7; then introducing nitrogen into the aqueous solution to remove oxygen for 30min, and sealing the beaker to form inert atmosphere; then adding 0.05g of initiator 2, 2' -azobis (2-methyl propionamidine) hydrochloride (AIBA) into the aqueous solution, and reacting for 6 hours at the constant temperature of 60 ℃ under normal pressure to obtain a colloidal polymer solution product;

(2) granulating, drying, crushing and screening: the gel-like polymer solution product was pelletized by a pelletizer into copolymer pellets of 4 to 6 mm, dried at 80 ℃ for 1 hour, and then sieved by pulverization to obtain an acrylamide copolymer product P4 of 20 to 80 mesh.

As a result, it was found that the viscosity-average molecular weight of the acrylamide copolymer product P4 was 1350X 10⁴The dissolving time is 115 min; and

according to the calculation of the charging amount, the structural unit A (wherein R is the total weight of the acrylamide copolymer product P4)₁Is H) is 97% by weight, structural unit B (where R is₂Is H, R₃Is ethylene, R₄、R₅、R₆And R₇Methyl) was contained in the amount of 3 wt%.

Example 5

An acrylamide copolymer was prepared by the same preparation method as in example 1, except that the boron-containing monomer used (monomer D was prepared according to Acs Macro Letters, 2012,1(5): 529-doped 532) had the following structure:

that is, in the monomer F having a structure represented by the formula (VI), R₂' is methyl, R₃' is ethylene, R₄′、 R₅′、R₆' and R₇' are each independently methyl.

The result was an acrylamide copolymer product P5.

As a result, it was found that the viscosity-average molecular weight of the acrylamide copolymer product P5 was 1500X 10⁴The dissolving time is 100 min; and

according to the calculation of the charging amount, the structural unit A (wherein R is the total weight of the acrylamide copolymer product P5)₁Methyl group) in an amount of 99.5 wt%, structural unit B (wherein R is₂Is H, R₃Is ethylene, R₄、R₅、R₆And R₇Methyl) was contained in the amount of 0.5 wt%.

Example 6

that is, in the monomer F having a structure represented by the formula (VI), R₂' is H, R₃' is ethylene, R₄′、R₅′、 R₆' and R₇' are each independently H.

The result was an acrylamide copolymer product P6.

As a result, it was found that the viscosity-average molecular weight of the acrylamide copolymer product P6 was 1480X 10⁴The dissolving time is 100 min; and

according to the calculation of the charging amount, the structural unit A (wherein R is the total weight of the acrylamide copolymer product P6)₁Is H) in an amount of 99.5% by weight, structureUnit B (wherein R₂Is H, R₃Is ethylene, R₄、R₅、R₆And R₇Is H) is present in an amount of 0.5% by weight.

Example 7

that is, in the monomer F having a structure represented by the formula (VI), R₂' is H, R₃' is butylene, R₄′、R₅′、 R₆' and R₇' are each independently H.

The result was an acrylamide copolymer product P7.

As a result, it was found that the viscosity-average molecular weight of the acrylamide copolymer product P7 was 1480X 10⁴The dissolving time is 105 min; and

according to the calculation of the charging amount, the structural unit A (wherein R is the total weight of the acrylamide copolymer product P7)₁Is H) in an amount of 90 wt.%, structural unit B (wherein R is₂Is H, R₃Is butylene, R₄、R₅、R₆And R₇Is H) is 10% by weight.

Comparative example 1

An acrylamide copolymer was prepared in the same manner as in example 1, except that the monomers C and D were used in a weight ratio of 1: 0.15, the resulting acrylamide copolymer product P8.

As a result, it was found that the viscosity-average molecular weight of the acrylamide copolymer product P8 was 840X 10⁴The dissolving time is 105 min; and

the material quantity is calculated and determined according to the material feeding quantity,structural unit A (wherein R is the same as the structural unit A) based on the total weight of the acrylamide copolymer product P8₁Is H) in an amount of 87% by weight, structural unit B (wherein R is₂Is H, R₃Is ethylene, R₄、R₅、R₆And R₇Methyl) was contained in the amount of 13% by weight.

Test example 1

The acrylamide copolymer products P1-P7 and P8 prepared in examples 1 to 7 and comparative example 1 were used as thermal thickeners, and the apparent viscosities of the respective thermal thickeners at different temperatures were measured.

The test method comprises the following steps:

firstly, preparing simulated mineral water with the total mineralization degree of 19334mg/L (wherein the total concentration of calcium ions and magnesium ions is 514mg/L) according to a method of enterprise standard Q/SH10201572-2006 of the Shengli Petroleum administration;

secondly, preparing a polymer (acrylamide copolymer products P1-P8) solution with the concentration of 3000mg/L by taking the simulated mineral water as a solvent, and stirring for 24 hours at room temperature;

finally, the apparent viscosities of the polymer solutions at different temperatures were measured using a rotational viscometer of the model DV-III ULTRA, available from Bohler fly (Brookfield) USA, with a constant shear rate of 25s^-1The measuring temperature interval is 30-95 ℃, and the heating rate is 2 ℃/min.

The measurement results are shown in table 1.

TABLE 1

As can be seen from the data in Table 1, the viscosity of the aqueous solution of the acrylamide copolymer products P1-P7 provided by the invention has small change at 50 ℃ or below, and then increases with the temperature, reaches the maximum value at 85 ℃, and further increases to 90 ℃, and the viscosity can still keep a high state. The acrylamide copolymer product P8 prepared in comparative example 1 has a low molecular weight due to improper mixture ratio of the two monomers, and the viscosity of the overall aqueous solution has a small increase with temperature. Therefore, the acrylamide copolymer product P1-P7 provided by the invention has obvious high-temperature thermal thickening property, belongs to a typical thermal thickening polymer, and is particularly suitable for the field of reservoir development with the formation temperature higher than 85 ℃.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. An acrylamide copolymer comprising a structural unit A and a structural unit B, wherein the structural unit A is a structural unit represented by formula (I), and the structural unit B is a structural unit represented by formula (II); based on the total weight of the acrylamide copolymer, the content of the structural unit A is 95-99.9 wt%, and the content of the structural unit B is 0.1-5 wt%;

wherein R is₁And R₂Each independently is hydrogen or C₁-C₄Alkyl of R₃Is C₁-C₁₂Alkylene of (A), R₄、R₅、R₆And R₇Each independently is hydrogen or C₁-C₁₂Alkyl groups of (a);

wherein the viscosity average molecular weight of the acrylamide copolymer is 1400-1800 ten thousand.

2. The acrylamide copolymer according to claim 1, wherein the content of the structural unit a is 96 to 99.7 wt% and the content of the structural unit B is 0.3 to 4 wt%, based on the total weight of the acrylamide copolymer.

3. The acrylamide copolymer according to claim 1, wherein R₁And R₂Each independently is H or methyl, R₃Is C₂-C₆Alkylene of (A), R₄、R₅、R₆And R₇Each independently is H or C₁-C₆Alkyl group of (1).

4. A preparation method of acrylamide copolymer is characterized in that the preparation method comprises the steps of carrying out polymerization reaction on a monomer mixture in water under the condition of solution polymerization reaction of olefin and in the presence of an initiator to obtain the acrylamide copolymer; the monomer mixture contains a monomer C and a monomer D, wherein the monomer C is a monomer with a structure shown in a formula (III), and the monomer D is a monomer with a structure shown in a formula (IV); and the weight ratio of the monomer C to the monomer D is 1: (0.001-0.05);

wherein R is₁' and R₂' independently of one another are hydrogen or C₁-C₄Alkyl of R₃' is C₁-C₁₂Alkylene of (A), R₄′、R₅′、R₆' and R₇' independently of one another are hydrogen or C₁-C₁₂Alkyl groups of (a);

wherein the initiator is selected from azo initiators or redox initiators, the amount of the azo initiators is 0.0002-0.05 wt% of the total weight of the monomers in the monomer mixture, and the amount of the redox initiators is 0.0002-0.05 wt% of the total weight of the monomers in the monomer mixture.

5. The method as claimed in claim 4, wherein the monomer C is used in an amount of 100-450 parts by weight and the monomer D is used in an amount of 0.18-15 parts by weight, based on 1000 parts by weight of water.

6. The method as claimed in claim 5, wherein the monomer C is used in an amount of 180-260 parts by weight and the monomer D is used in an amount of 0.36-6 parts by weight.

7. The process of claim 4, wherein the azo-based initiator is used in an amount of 0.0018 to 0.018 weight percent based on the total weight of monomers in the monomer mixture; the dosage of the redox initiator is 0.0018 to 0.018 weight percent of the total weight of the monomers in the monomer mixture; the redox initiator comprises an oxidizing agent and a reducing agent, wherein the reducing agent is an inorganic reducing agent and/or an organic reducing agent, and the weight ratio of the oxidizing agent to the reducing agent is (0.1-1): 1.

8. the process according to claim 7, wherein the azo-based initiator is a water-soluble azo-based initiator selected from at least one of 2,2 ' -azobisisobutyronitrile, 2 ' -azobisisobutylamidine dihydrochloride, azobisisoheptonitrile, 2 ' -azobis (2-methylpropionamidine) hydrochloride, 2 ' -azo [2- (2-imidazolin-2-yl) propane ] dihydrochloride, and 4,4 ' -azobis (4-cyanovaleric acid); the oxidant is at least one of benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, 2, 5-dimethyl-2, 5-bis (hydroperoxide) hexane, ammonium persulfate, sodium persulfate and potassium persulfate; the inorganic reducing agent is at least one of ferrous sulfate, ammonium ferrous sulfate, cuprous chloride, potassium sulfite, sodium sulfite, ammonium bisulfite, potassium bisulfite, sodium thiosulfate, potassium thiosulfate, rongalite and sodium bisulfite; the organic reducing agent is at least one of N, N-dimethylethanolamine, N, N-dimethylpiperazine, tetramethylurea, N, N-dimethylethylenediamine and N, N, N ', N' -tetramethylethylenediamine.

9. The method of claim 4, wherein the monomer C is an acrylamide-based monomer that is one or more of acrylamide, methacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-isopropylacrylamide, N-methylolacrylamide, and N-hydroxyethylacrylamide; and

the monomer D is shown as a formula (IV), wherein R₂' is H, R₃' is C₂-C₆Alkylene of (A), R₄′、R₅′、R₆' and R₇' each independently is H or C₁-C₆An alkyl group.

10. The process of claim 4, wherein the solution polymerization conditions of the olefin comprise: the solution polymerization reaction of the olefin is carried out in an inert atmosphere, the initiator is an azo initiator, the temperature is 40-70 ℃, the time is 2-10h, and the pH value is 6-8.

11. The process of claim 4, wherein the solution polymerization conditions of the olefin comprise: the solution polymerization reaction of the olefin is carried out in an inert atmosphere, the initiator is a redox initiator, the temperature is 15-30 ℃, the time is 5-10h, and the pH value is 6-8.

12. The method according to any one of claims 4 to 11, wherein the method further comprises drying the polymer obtained after the polymerization, wherein the drying conditions comprise: the temperature is 40-120 ℃ and the time is 0.2-4 hours.

13. Use of an acrylamide copolymer according to any one of claims 1 to 3 or prepared by a method according to any one of claims 5 to 12 as a thermal thickener.