A salt-resistant and hydrophobic associating polyacrylamide for shape-complementary fracturing oil production and its preparation method

Abstract

This patent relates to the field of oilfield chemical fracturing. Specifically, it is a salt-resistant hydrophobic associating polyacrylamide for fracturing oil production with complementary shapes and its preparation method, which uses pure water, acrylamide, acrylic acid, sodium hydroxide, urea, a first hydrophobic monomer, a second hydrophobic monomer, a salt-resistant monomer, a complexing agent, a chain transfer agent, an initiator, an oxidizing agent and a reducing agent. In this preparation method, the first hydrophobic monomer and the second hydrophobic monomer are first synthesized. Then, pure water, acrylamide, acrylic acid, sodium hydroxide, urea, the first hydrophobic monomer, the second hydrophobic monomer, and the salt-resistant monomer are mixed and stirred evenly according to certain mass fractions, and then cooled down. The complexing agent, the chain transfer agent, the initiator, the oxidizing agent and the reducing agent are sequentially added. After the reaction is completed, the rubber block is granulated, dried and ground to obtain a salt-resistant hydrophobic associating polyacrylamide for fracturing oil production with complementary shapes. The two hydrophobic monomers of this polyacrylamide have a complementary shape effect, effectively improving the viscosity in salt water.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield chemical fracturing, and particularly relates to a salt-resistant and hydrophobic associating polyacrylamide for shape-complementary fracturing oil production and a preparation method thereof. Background Art

[0002] With the rapid development of China's economy, the demand for energy is increasing day by day. As an important energy resource, the stable supply of oil is crucial for national energy security. However, in the process of oil exploitation, especially for low-permeability oilfields, conventional exploitation methods are often difficult to achieve efficient exploitation. Therefore, fracturing technology, as an important means to improve crude oil recovery, has been widely applied at home and abroad.

[0003] Fracturing technology is to inject high-pressure liquid into the formation to form fractures, thereby increasing the permeability of the oil reservoir and improving the fluidity and recovery rate of crude oil. In the fracturing process, the selection and use of fracturing fluid are crucial. Polyacrylamide (PAM), as a commonly used fracturing fluid additive, has good viscosity-increasing properties, can improve the sand-carrying capacity, and reduce the frictional resistance, which is a key factor in achieving the fracturing effect. However, in practical applications, polyacrylamide is prone to degradation in high-temperature and high-salt environments, resulting in a decrease in its viscosity-increasing properties and affecting the fracturing effect. In addition, polyacrylamide is prone to molecular chain breakage under high-pressure shear conditions, further reducing its use effect. Therefore, the development of a salt-resistant hydrophobic associating polyacrylamide has become an important research direction for fracturing fluids. In the prior art, hydrophobic associating polyacrylamide is prepared by introducing hydrophobic groups into the polyacrylamide molecule to improve its stability in high-temperature and high-salt environments. In the molecular structure of hydrophobic associating polyacrylamide, the hydrophobic groups can form hydrophobic microdomains, enhancing the intermolecular interaction force, thereby improving the thermal stability and salt resistance of the polymer.

[0004] The synthesis of the salt-resistant hydrophobic associating polyacrylamide for fracturing proposed in this patent aims to solve the problem of viscosity stability of existing fracturing fluids in high-temperature and high-salt environments. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to improve the salt resistance and high-temperature shear resistance of fracturing fluid. The present invention provides a salt-resistant hydrophobic associating polyacrylamide for shape-complementary fracturing oil production, and the preparation method includes the following steps:

[0006] (1) By mass fraction, 166 - 222 parts of 1,11 - dodecadiene or 1,13 - tetradecadiene or 1,15 - hexadecadiene are added with 8 - 12 parts of borane and then subjected to a substitution reaction with 68 - 102 parts of thionyl dichloride to obtain 12 - chloro - 1 - dodecene or 14 - chloro - 1 - tetradecene or 16 - chloro - 1 - hexadecene. 20 - 25 parts by mass of tripropylamine or tributylamine are dissolved in 80 - 100 parts of toluene, then transferred into a three - necked flask, and nitrogen is introduced. The three - necked flask is placed in an ice - water bath, and stirring is started. Weigh 90 - 150 parts of 12 - chloro - 1 - dodecene or 14 - chloro - 1 - tetradecene or 16 - chloro - 1 - hexadecene and dissolve it in 200 - 250 parts of toluene, transfer it into a constant - pressure dropping funnel, and then slowly drop it into the three - necked flask. After the liquid in the constant - pressure dropping funnel is completely dropped, until the reaction is complete. After the reaction, the product is soaked and washed in 300 - 400 parts of acetone, and after vacuum filtration, it is dried in a vacuum oven at a temperature of 40 - 60 °C for 15 - 20 h to obtain the first hydrophobic monomer. The structural formula of the first hydrophobic monomer is: .

[0007] (2) React 15 - 27 parts of 10 - hydroxydecanoic acid and 5 - 7 parts of cyclopropanol under esterification reaction conditions. Then, dissolve 18 - 25 parts of the above esterification reaction product and 10 - 15 parts of triethylamine in 40 - 50 parts of toluene, transfer it into a three - necked flask, and introduce nitrogen. The three - necked flask is placed in an ice - water bath, and the stirring device is started. Dissolve 8 - 12 parts of acryloyl chloride in 15 - 30 parts of toluene, transfer it into a constant - pressure dropping funnel, and slowly drop it. After dropping, react at 0 - 5 °C for 10 - 15 h. After the reaction, the product is soaked and washed in 150 - 300 parts of acetone, and after vacuum filtration, it is dried in a vacuum oven at a temperature of 40 - 60 °C for 10 - 20 h to obtain the second hydrophobic monomer: .

[0008] (3) Solution preparation: Mix 1000 - 1100 parts of pure water, 220 - 280 parts of acrylamide, 50 - 80 parts of acrylic acid, 25 - 45 parts of sodium hydroxide, 5 - 10 parts of urea, 1 - 5 parts of the first hydrophobic monomer, 1 - 4 parts of the second hydrophobic monomer, and 40 - 50 parts of salt - resistant monomer evenly by stirring, then freeze it to - 2 - 0 °C and transfer it into a heat - preservation kettle;

[0009] (4) At the 0th minute, introduce nitrogen into the solution in the reaction kettle to remove oxygen and add 0.001 - 0.002 parts of complexing agent and 0.003 - 0.006 parts of chain transfer agent;

[0010] (5) At the 15th minute, add 0.02 - 0.5 parts of initiator;

[0011] (6) At the 20th minute, 0.002 - 0.006 parts of an oxidant are added;

[0012] (7) At the 21st minute, 0.002 - 0.006 parts of a reducing agent are added. After the polymerization reaction starts, the nitrogen gas pipe is removed and nitrogen gas supply is stopped;

[0013] (8) After the reaction is complete, it is cured for 1.5 - 2.5 h, and then pelletized, dried, and ground.

[0014] The anti - salt monomer is one of 2 - acrylamido - 2 - methylpropanesulfonic acid and N - vinylpyrrolidone. The complexing agent is one of sodium citrate, sodium ethylenediaminetetraacetate, and sodium diethylenetriaminepentaacetate. The chain transfer agent is one of sodium hypophosphite and sodium methallylsulfonate. The initiator is one or more of azodiisobutyramidine hydrochloride and azodiisobimidazoline hydrochloride. The oxidant is one of tert - butyl hydroperoxide and ammonium persulfate. The reducing agent is one of ammonium ferrous sulfate and sodium metabisulfite.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: In the synthesis, the first and second hydrophobic monomers are used. Due to their special shape structures, the two monomers can form a shape - complementary effect. That is, the first hydrophobic monomer has a claw - like structure that can be complementary to the shape of the three - membered ring structure of the second hydrophobic monomer to a certain extent. The mechanism diagram is shown in the appendix Figure 1 , which improves the viscosity of the hydrophobically associating polyacrylamide in salt water. At the same time, the interaction between the two hydrophobic monomers and the anti - salt effect of the anti - salt monomer endow the product with good anti - salt ability and high - temperature shear resistance. Brief Description of the Drawings

[0016] Figure 1 It is the complementary mechanism diagram of the first and second hydrophobic monomers of the present invention;

[0017] Figure 2 It is the viscosity test diagram of Example 1 of the present invention in salt water;

[0018] Figure 3 It is the viscosity test diagram of Example 2 of the present invention in salt water;

[0019] Figure 4 It is the viscosity test diagram of Example 3 of the present invention in salt water;

[0020] Figure 5 It is the viscosity test diagram of Example 4 of the present invention in salt water;

[0021] Figure 6 It is the viscosity test diagram of Example 5 of the present invention in salt water;

[0022] Figure 7 It is the viscosity test diagram of Example 6 of the present invention in salt water;

[0023] Figure 8 Viscosity test chart of Comparative Example 1 of the present invention in brine;

[0024] Figure 9 Viscosity test chart of Comparative Example 2 of the present invention in brine;

[0025] Figure 10 Viscosity test chart of Examples 1-6 and Comparative Examples 1-2 of the present invention after high-temperature shearing;

[0026] Figure 11 Sand-carrying performance test chart of Examples 1-6 and Comparative Examples 1-2 of the present invention. Detailed implementation manners

[0027] The following are specific embodiments of the present invention, which further describe the operation scheme of the present invention. However, the protection scope of the present invention includes but is not limited to these embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0028] Example 1: A salt-resistant and hydrophobic associating polyacrylamide for fracturing oil production with complementary shapes, and its preparation steps are as follows:

[0029] (1) By mass, first add 166 parts of 1,11-dodecadiene and 8 parts of borane for addition reaction, and then perform substitution reaction with 68 parts of thionyl chloride to obtain 12-chloro-1-dodecene. Dissolve 20 parts of tripropylamine in 80 parts of toluene, then transfer it to a three-necked flask, and introduce nitrogen. Place the three-necked flask in an ice-water bath and turn on the stirring device. Weigh 95 parts of 12-chloro-1-dodecene and dissolve it in 200 parts of toluene, transfer it to a constant-pressure dropping funnel, and then slowly drop it into the three-necked flask. Wait until the liquid in the constant-pressure dropping funnel is dropped completely until the reaction is complete. After the reaction is completed, soak the product in 400 parts of acetone for cleaning, perform vacuum filtration, and then dry it in a vacuum oven at a temperature of 50 °C for 20 h to obtain the first hydrophobic monomer;

[0030]

[0031]

[0032] (2) By mass, react 18 parts of 10-hydroxydecanoic acid and 5.6 parts of cyclopropanol under esterification reaction conditions. Dissolve 20 parts of the above esterification reaction product and 12 parts of triethylamine in 45 parts of toluene, then transfer it to a three-necked flask, and introduce nitrogen. Place the three-necked flask in an ice-water bath and turn on the stirring device. Dissolve 10.2 parts of acryloyl chloride in 20 parts of toluene, transfer it to a constant-pressure dropping funnel, slowly drop it, and react at 2 °C for 12 h after dropping. After the reaction is completed, soak the product in 200 parts of acetone for cleaning, perform vacuum filtration, and then dry it in a vacuum oven at a temperature of 50 °C for 15 h to obtain the second hydrophobic monomer;

[0032] (3)Solution preparation: By mass fraction, 1010 parts of pure water, 275 parts of acrylamide, 72 parts of acrylic acid, 39 parts of sodium hydroxide, 6 parts of urea, 3.5 parts of the first hydrophobic monomer, 2.3 parts of the second hydrophobic monomer, and 40 parts of 2-acrylamido-2-methylpropanesulfonic acid are mixed and stirred evenly, then frozen to -2 °C and transferred to a heat preservation kettle;

[0033] (4)At the 0th minute, nitrogen is introduced into the solution in the reaction kettle to remove oxygen, and 0.0018 parts of diethylenetriaminepentaacetic acid sodium salt and 0.004 parts of sodium hypophosphite are added;

[0034] (5)At the 15th minute, 0.06 parts of 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 0.2 parts of 2,2'-azobis(2-methylpropionitrile) dihydrochloride are added;

[0035] (6)At the 20th minute, 0.004 parts of tert-butyl hydroperoxide are added;

[0036] (7)At the 21st minute, 0.004 parts of ammonium ferrous sulfate are added. After the polymerization reaction starts, the nitrogen pipe is removed and nitrogen supply is stopped;

[0037] (8)After the reaction is complete, it is aged for 2 h, then granulated, dried, and ground. The reaction formula is as follows: .

[0038] Example 2: A salt-resistant hydrophobic associating polyacrylamide for shape-complementary fracturing oil production, and its preparation steps are as follows:

[0039] (1)First, 166 parts of 1,11-dodecadiene are subjected to an addition reaction with 8 parts of borane and then a substitution reaction with 68 parts of thionyl chloride to obtain 12-chloro-1-dodecene. 23 parts by mass of tributylamine are dissolved in 80 parts of toluene, then transferred to a three-necked flask, and nitrogen is introduced. The three-necked flask is placed in an ice-water bath, and the stirring device is started. 100 parts of 12-chloro-1-dodecene are weighed and dissolved in 200 parts of toluene, transferred to a constant-pressure dropping funnel, and then slowly dropped into the three-necked flask. After the liquid in the constant-pressure dropping funnel is dropped, the reaction is continued until it is complete. After the reaction is completed, the product is soaked and washed in 400 parts of acetone, filtered under reduced pressure, and dried in a vacuum oven at 50 °C for 20 h to obtain the first hydrophobic monomer;

[0040] (2) Taking 23 parts by mass of 10 - hydroxydecanoic acid and 5 parts of cyclopropanol, reacting them under esterification reaction conditions. Dissolve 22 parts of the above - mentioned esterification reaction product and 11 parts of triethylamine in 45 parts of toluene, then transfer it into a three - necked flask, and introduce nitrogen. Place the three - necked flask in an ice - water bath and turn on the stirring device. Dissolve 11 parts of acryloyl chloride in 20 parts of toluene, transfer it to a constant - pressure dropping funnel, slowly add drops. After the addition is complete, react at 2 °C for 12 h. After the reaction is completed, soak and wash the product in 200 parts of acetone, carry out vacuum filtration, and then dry it in a vacuum oven at 50 °C for 15 h to obtain the second hydrophobic monomer;

[0041] (3) Solution preparation: Taking 1000 parts by mass of pure water, 275 parts of acrylamide, 70 parts of acrylic acid, 38 parts of sodium hydroxide, 5.5 parts of urea, 3.3 parts of the first hydrophobic monomer, 2.2 parts of the second hydrophobic monomer, and 43 parts of 2 - acrylamido - 2 - methylpropanesulfonic acid, mix and stir evenly, then freeze to - 2 °C and transfer it to a heat - preservation kettle;

[0042] (4) At the 0th minute, introduce nitrogen into the solution in the reaction kettle to remove oxygen and add 0.0019 part of diethylenetriaminepentaacetic acid sodium salt and 0.0041 part of sodium hypophosphite;

[0043] (5) At the 15th minute, add 0.065 part of 2,2' - azobis(2 - methylpropionamidine) dihydrochloride and 0.22 part of 2,2' - azobis(2 - methylpropionitrile) hydrochloride;

[0044] (6) At the 20th minute, add 0.0042 part of ammonium persulfate;

[0045] (7) At the 21st minute, add 0.0043 part of ammonium ferrous sulfate. After the polymerization reaction starts, remove the nitrogen pipe and stop nitrogen introduction;

[0046] (8) After the reaction is complete, cure for 2 h, then granulate, dry, and grind. The reaction formula is as follows: .

[0047] Example 3: (1) Taking 194 parts by mass of 1,13 - tetradecadiene, first adding it with 10 parts of borane and then carrying out a substitution reaction with 85 parts of thionyl chloride to obtain 14 - chloro - 1 - tetradecene. Dissolve 21 parts by mass of tripropylamine in 80 parts of toluene, then transfer it into a three - necked flask, and introduce nitrogen. Place the three - necked flask in an ice - water bath and turn on the stirring device. Weigh 110 parts of 14 - chloro - 1 - tetradecene and dissolve it in 200 parts of toluene, transfer it to a constant - pressure dropping funnel, and then slowly add drops to the three - necked flask. Wait until the liquid in the constant - pressure dropping funnel is added completely until the reaction is complete. After the reaction is completed, soak and wash the product in 400 parts of acetone, carry out vacuum filtration, and then dry it in a vacuum oven at 50 °C for 20 h to obtain the first hydrophobic monomer;

[0048] (2) By mass fraction, react 25 parts of 10-hydroxydecanoic acid and 6 parts of cyclopropanol under esterification reaction conditions. Dissolve 23 parts of the above esterification reaction product and 14 parts of triethylamine in 45 parts of toluene, then transfer it to a three-necked flask, and introduce nitrogen. Place the three-necked flask in an ice-water bath and turn on the stirring device. Dissolve 11.5 parts of acryloyl chloride in 20 parts of toluene, transfer it to a constant-pressure dropping funnel, and slowly add drops. After the addition, react at 2 °C for 12 h. After the reaction is completed, soak and wash the product in 200 parts of acetone, perform suction filtration under reduced pressure, and dry it in a vacuum oven at 50 °C for 15 h to obtain the second hydrophobic monomer;

[0049] (3) Solution preparation: By mass fraction, mix 1060 parts of pure water, 278 parts of acrylamide, 73 parts of acrylic acid, 39 parts of sodium hydroxide, 5.2 parts of urea, 3.6 parts of the first hydrophobic monomer, 2.3 parts of the second hydrophobic monomer, and 44 parts of 2-acrylamido-2-methylpropanesulfonic acid and stir evenly, then freeze to -2 °C and transfer it to a heat preservation kettle;

[0050] (4) At the 0th minute, introduce nitrogen into the solution in the reaction kettle to remove oxygen and add 0.0017 parts of diethylenetriaminepentaacetic acid sodium salt and 0.0042 parts of sodium hypophosphite;

[0051] (5) At the 15th minute, add 0.065 parts of 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 0.23 parts of 2,2'-azobis(2-methylpropionitrile) dihydrochloride;

[0052] (6) At the 20th minute, add 0.004 parts of tert-butyl hydroperoxide;

[0053] (7) At the 21st minute, add 0.004 parts of ammonium ferrous sulfate. After the polymerization reaction starts, remove the nitrogen pipe and stop passing nitrogen;

[0054] (8) After the reaction is complete, cure for 2 h, then granulate, dry, and grind. The reaction formula is as follows: .

[0055] Example 4: (1) By mass, first, 194 parts of 1,13-tetradecadiene are added with 10 parts of borane and then subjected to a substitution reaction with 85 parts of thionyl chloride to obtain 14-chloro-1-tetradecene. 25 parts of tributylamine are dissolved in 80 parts of toluene, then transferred into a three-necked flask, and nitrogen is introduced. The three-necked flask is placed in an ice-water bath, and the stirring device is started. Weigh 115 parts of 14-chloro-1-tetradecene, dissolve it in 200 parts of toluene, transfer it to a constant-pressure dropping funnel, and slowly drop it into the three-necked flask. Wait until the liquid in the constant-pressure dropping funnel is completely dropped until the reaction is complete. After the reaction is completed, the product is soaked and washed in 400 parts of acetone, filtered under reduced pressure, and then dried in a vacuum oven at a temperature of 50 °C for 20 h to obtain the first hydrophobic monomer;

[0056] (2) By mass, 22.3 parts of 10-hydroxydecanoic acid and 6.2 parts of cyclopropanol are reacted under esterification reaction conditions. 22.5 parts of the above esterification reaction product and 13.8 parts of triethylamine are dissolved in 45 parts of toluene, then transferred into a three-necked flask, and nitrogen is introduced. The three-necked flask is placed in an ice-water bath, and the stirring device is started. 11.6 parts of acryloyl chloride are dissolved in 20 parts of toluene, transferred to a constant-pressure dropping funnel, slowly dropped, and after dropping, the reaction is carried out at 2 °C for 12 h. After the reaction is completed, the product is soaked and washed in 200 parts of acetone, filtered under reduced pressure, and then dried in a vacuum oven at a temperature of 50 °C for 15 h to obtain the second hydrophobic monomer;

[0057] (3) Solution preparation: By mass, 1030 parts of pure water, 277 parts of acrylamide, 76 parts of acrylic acid, 40 parts of sodium hydroxide, 5.6 parts of urea, 3.7 parts of the first hydrophobic monomer, 2.6 parts of the second hydrophobic monomer, and 43 parts of 2-acrylamido-2-methylpropanesulfonic acid are mixed and stirred evenly, then frozen to -2 °C and transferred to a heat preservation kettle;

[0058] (4) At the 0th minute, nitrogen is introduced into the solution in the reaction kettle to remove oxygen, and 0.0018 parts of diethylenetriaminepentaacetic acid sodium salt and 0.0045 parts of sodium hypophosphite are added;

[0059] (5) At the 15th minute, 0.067 parts of 2,2'-azobis(2-methylimidazoline) hydrochloride and 0.23 parts of 2,2'-azobis(2-methylpropionamidine) dihydrochloride are added;

[0060] (6) At the 20th minute, 0.0045 parts of tert-butyl hydroperoxide are added;

[0061] (7) At the 21st minute, 0.0045 parts of sodium metabisulfite are added. After the polymerization reaction starts, the nitrogen pipe is removed and nitrogen injection is stopped;

[0062] (8) After the reaction is complete, it is cured for 2 h, then granulated, dried, and ground. The reaction formula is as follows: 。

[0063] Example 5: (1) By mass, first add 222 parts of 1,15 - hexadecadiene with 12 parts of borane, and then carry out a substitution reaction with 102 parts of thionyl chloride to obtain 16 - chloro - 1 - hexadecene. Dissolve 25 parts of tripropylamine in 80 parts of toluene, then transfer it to a three - necked flask, and introduce nitrogen. Place the three - necked flask in an ice - water bath and turn on the stirring device. Weigh 130 parts of 16 - chloro - 1 - hexadecene and dissolve it in 200 parts of toluene, transfer it to a constant - pressure dropping funnel, and then slowly drop it into the three - necked flask. Wait until the liquid in the constant - pressure dropping funnel is completely dropped and the reaction is complete. After the reaction is over, soak the product in 300 - 400 parts of acetone for cleaning, carry out vacuum filtration, and then dry it in a vacuum oven at a temperature of 50 °C for 20 h to obtain the first hydrophobic monomer;

[0064] (2) By mass, react 25.3 parts of 10 - hydroxydecanoic acid and 6.3 parts of cyclopropanol under esterification reaction conditions. Dissolve 24.5 parts of the above - mentioned esterification reaction product and 13.8 parts of triethylamine in 45 parts of toluene, then transfer it to a three - necked flask, and introduce nitrogen. Place the three - necked flask in an ice - water bath and turn on the stirring device. Dissolve 10.6 parts of acryloyl chloride in 20 parts of toluene, transfer it to a constant - pressure dropping funnel, slowly drop it, and react at 2 °C for 12 h after dropping. After the reaction is over, soak the product in 200 parts of acetone for cleaning, carry out vacuum filtration, and then dry it in a vacuum oven at a temperature of 50 °C for 15 h to obtain the second hydrophobic monomer;

[0065] (3) Solution preparation: By mass, mix 1060 parts of pure water, 278 parts of acrylamide, 75 parts of acrylic acid, 39 parts of sodium hydroxide, 5.8 parts of urea, 3.5 parts of the first hydrophobic monomer, 2.6 parts of the second hydrophobic monomer, and 47 parts of 2 - acrylamido - 2 - methylpropanesulfonic acid and stir evenly, then freeze it to - 2 °C and transfer it to a heat - preservation kettle;

[0066] (4) At the 0th minute, introduce nitrogen into the solution in the reaction kettle to remove oxygen and add 0.0018 parts of diethylenetriaminepentaacetic acid sodium salt and 0.0043 parts of sodium hypophosphite;

[0067] (5) At the 15th minute, add 0.058 parts of 2,2' - azobis(2 - methylpropionamidine) dihydrochloride and 0.25 parts of 2,2' - azobis(2 - methylpropionitrile) hydrochloride;

[0068] (6) At the 20th minute, add 0.0043 parts of ammonium persulfate;

[0069] (7) At the 21st minute, add 0.0043 parts of ammonium ferrous sulfate. After the polymerization reaction starts, remove the nitrogen pipe and stop passing nitrogen;

[0070] After the reaction is complete, cure for 2 h, then granulate, dry, and grind. The reaction formula is as follows: 。

[0071] Example 6: (1) By mass, first add 222 parts of 1,15 - hexadecene to react with 12 parts of borane and then perform a substitution reaction with 102 parts of thionyl chloride to obtain 16 - chloro - 1 - hexadecene. Dissolve 24 parts of tributylamine in 80 parts of toluene, then transfer it to a three - necked flask, and introduce nitrogen. Place the three - necked flask in an ice - water bath and start the stirring device. Weigh 145 parts of 16 - chloro - 1 - hexadecene and dissolve it in 200 parts of toluene, transfer it to a constant - pressure dropping funnel, and slowly add it dropwise to the three - necked flask. Wait until the liquid in the constant - pressure dropping funnel is completely added and the reaction is complete. After the reaction is over, soak and wash the product in 400 parts of acetone, perform suction filtration under reduced pressure, and then dry it in a vacuum oven at 50 °C for 20 h to obtain the first hydrophobic monomer;

[0072] (2) By mass, react 23.7 parts of 10 - hydroxydecanoic acid and 6.1 parts of cyclopropanol under esterification reaction conditions. Dissolve 22.7 parts of the above - mentioned esterification reaction product and 11.5 parts of triethylamine in 45 parts of toluene, then transfer it to a three - necked flask, and introduce nitrogen. Place the three - necked flask in an ice - water bath and start the stirring device. Dissolve 11.3 parts of acryloyl chloride in 20 parts of toluene, transfer it to a constant - pressure dropping funnel, slowly add it dropwise, and after dropping, react at 2 °C for 12 h. After the reaction is over, soak and wash the product in 200 parts of acetone, perform suction filtration under reduced pressure, and then dry it in a vacuum oven at 50 °C for 15 h to obtain the second hydrophobic monomer;

[0073] (3) Solution preparation: By mass, mix 1055 parts of pure water, 274 parts of acrylamide, 73 parts of acrylic acid, 39 parts of sodium hydroxide, 6.3 parts of urea, 3.8 parts of the first hydrophobic monomer, 1.9 parts of the second hydrophobic monomer, and 45 parts of N - vinylpyrrolidone and stir evenly, then freeze to - 2 °C and transfer it to a heat - preservation kettle;

[0074] (4) At the 0th minute, introduce nitrogen into the solution in the reaction kettle to remove oxygen and add 0.0018 parts of diethylenetriaminepentaacetic acid sodium salt and 0.0047 parts of sodium hypophosphite;

[0075] (5) At the 15th minute, add 0.07 parts of 2,2' - azobis(2 - methylpropionamidine) dihydrochloride and 0.19 parts of 2,2' - azobis(2 - methylpropionitrile) hydrochloride;

[0076] (6) At the 20th minute, add 0.0044 parts of tert - butyl hydroperoxide;

[0077] (7) At the 21st minute, add 0.0044 parts of ammonium ferrous sulfate. After the polymerization reaction starts, remove the nitrogen pipe and stop passing nitrogen;

[0078] (8) After the reaction is complete, cure for 2 h, then granulate, dry, and grind. The reaction formula is as follows: .

[0079] Comparative Example 1: (1) By mass fraction, react 20 parts of 10-hydroxydecanoic acid and 5 parts of cyclopropanol under esterification reaction conditions. Dissolve 20 parts of the above esterification reaction product and 12 parts of triethylamine in 45 parts of toluene, then transfer to a three-necked flask, and introduce nitrogen. Place the three-necked flask in an ice-water bath and turn on the stirring device. Dissolve 10 parts of acryloyl chloride in 20 parts of toluene, transfer to a constant-pressure dropping funnel, and slowly add dropwise. After the addition, react at 2 °C for 12 h. After the reaction is completed, soak and wash the product in 200 parts of acetone, filter under reduced pressure, and dry in a vacuum oven at 50 °C for 15 h to obtain a hydrophobic monomer;

[0080] (2) Solution preparation: By mass fraction, mix 1060 parts of pure water, 280 parts of acrylamide, 71 parts of acrylic acid, 38 parts of sodium hydroxide, 5.8 parts of urea, 4 parts of the hydrophobic monomer, and 45 parts of 2-acrylamido-2-methylpropanesulfonic acid and stir evenly, then freeze to -2 °C and transfer to a heat-insulating kettle;

[0081] (3) At the 0th minute, introduce nitrogen into the solution in the reaction kettle to remove oxygen and add 0.0019 parts of diethylenetriaminepentaacetic acid sodium salt and 0.0042 parts of sodium hypophosphite;

[0082] (4) At the 15th minute, add 0.07 parts of 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 0.22 parts of 2,2'-azobis(2-methylpropionitrile) hydrochloride;

[0083] (5) At the 20th minute, add 0.0045 parts of tert-butyl hydroperoxide;

[0084] (6) At the 21st minute, add 0.0045 parts of ammonium ferrous sulfate. After the polymerization reaction starts, remove the nitrogen pipe and stop passing nitrogen;

[0085] (7) After the reaction is complete, cure for 2 h, then granulate, dry, and grind.

[0086] Comparative Example 2: (1) By mass parts, first 222 parts of 1,15 - hexadecene were added with 10 parts of borane and then subjected to a substitution reaction with 85 parts of thionyl chloride to obtain 16 - chloro - 1 - hexadecene. 20 parts of tripropylamine were dissolved in 80 parts of toluene, then transferred to a three - necked flask, and nitrogen was introduced. The three - necked flask was placed in an ice - water bath, and the stirring device was started. 100 parts of 16 - chloro - 1 - hexadecene were weighed and dissolved in 200 parts of toluene, transferred to a constant - pressure dropping funnel, and slowly added dropwise to the three - necked flask. After the liquid in the constant - pressure dropping funnel was added dropwise until the reaction was complete. After the reaction, the product was soaked and washed in 400 parts of acetone, filtered under reduced pressure, and then dried in a vacuum oven at 50 °C for 20 h to obtain a hydrophobic monomer;

[0087] (2) Solution preparation: By mass parts, 1065 parts of pure water, 265 parts of acrylamide, 78 parts of acrylic acid, 42 parts of sodium hydroxide, 6 parts of urea, 4.1 parts of hydrophobic monomer, and 40 parts of 2 - acrylamido - 2 - methylpropanesulfonic acid were mixed and stirred evenly, then frozen to - 2 °C and transferred to a heat - insulating kettle;

[0088] (3) At the 0th minute, nitrogen was introduced into the solution in the reaction kettle to remove oxygen, and 0.0018 parts of diethylenetriaminepentaacetic acid sodium salt and 0.0045 parts of sodium hypophosphite were added;

[0089] (4) At the 15th minute, 0.055 parts of 2,2′ - azobis(2 - methylpropionamidine) dihydrochloride and 0.28 parts of 2,2′ - azobis(2 - methylpropionitrile) hydrochloride were added;

[0090] (5) At the 20th minute, 0.0035 parts of tert - butyl hydroperoxide were added;

[0091] (6) At the 21st minute, 0.0035 parts of ammonium ferrous sulfate were added. After the polymerization reaction started, the nitrogen pipe was removed and nitrogen supply was stopped;

[0092] (7) After the reaction was complete, it was aged for 2 h, then granulated, dried, and ground.

[0093] Test Example: The performances of Examples 1 - 6 and Comparative Examples 1 - 2 were evaluated.

[0094] (1) Thickening property: Preparation of brine: 6.93 g of calcium chloride, 4.67 g of magnesium chloride, 21.07 g of sodium sulfate, and 47.33 g of sodium chloride were accurately weighed, and then dissolved and diluted to 2 L with pure water to obtain brine with a salinity of 40000.

[0095] The samples of Examples 1-6 and Comparative Examples 1-2 were respectively prepared into solutions with mass fractions of 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55% and 0.6% using brine with a salinity of 40,000. After stirring for 5 minutes, the viscosities were measured respectively. The specific results are shown in the appendix Figure 2-9 As shown, the results indicate that for Examples 1-6, the two hydrophobic monomers form a shape-complementary effect due to their special shapes. That is, the claw-like structure of the first hydrophobic monomer can interact with the ring structure of the second hydrophobic monomer and bind together, and the two monomers can also form a hydrophobic association effect. Therefore, the viscosity of the polymer in brine can be significantly increased. In Comparative Examples 1-2, only a single first or second hydrophobic monomer participates in the association effect, and the effect is lower than that of the examples. In solutions with a concentration above 0.55%, the viscosity increase of Examples 1-6 and Comparative Example 1 or 2 both exceeds 50%.

[0096] (2) Viscosity and retention rate at high temperature: To balance viscosity and solubility, the samples of Examples 1-6 and Comparative Examples 1-2 were respectively prepared into solutions with a mass fraction of 0.4% using brine with a salinity of 40,000. Then, the viscosities of each solution after shearing at 120 °C for 60 min at a speed of 170 s -1 were measured. The results are shown in the appendix Figure 10 As shown, the results indicate that the polymer solutions of Examples 1-6 have better high-temperature shear resistance under the hydrophobic association effect and shape-complementary effect than the comparative examples.

[0097] (3) Sand-carrying performance: 0.8 g of the samples of Examples 1-6 and Comparative Examples 1-2 were respectively weighed and dissolved in 199.2 g of brine. After standing for 30 min after dissolution, 100 mL was taken and placed in a 250 mL beaker, and 25 mL of fine sand (20-40 mesh) was added. After stirring evenly, it was transferred to a graduated cylinder, and the sedimentation rate of the fine sand was observed and recorded. The specific results are shown in the appendix Figure 11 As shown, the results indicate that Examples 1-6 have good association and shape-complementary effects, resulting in good sand-carrying ability, while Comparative Examples 1-2 have weak association effects and poor sand-carrying ability.

Claims

1. A salt-resistant hydrophobic associating polyacrylamide for shape-complementary fracturing oil production, characterized in that, The raw materials include: pure water, acrylamide, acrylic acid, sodium hydroxide, urea, a first hydrophobic monomer, a second hydrophobic monomer, a salt-resistant monomer, a complexing agent, a chain transfer agent, an initiator, an oxidizing agent and a reducing agent; By mass, 166 - 222 parts of 1,11-dodecadiene or 1,13-tetradecadiene or 1,15-hexadecadiene are added with 8 - 12 parts of borane and then subjected to a substitution reaction with 68 - 102 parts of thionyl chloride to obtain 12-chloro-1-dodecene or 14-chloro-1-tetradecene or 16-chloro-1-hexadecene. 20 - 25 parts by mass of tripropylamine or tributylamine are dissolved in 80 - 100 parts of toluene, then transferred into a three-necked flask, and nitrogen is introduced. The three-necked flask is placed in an ice-water bath and stirring is started. Weigh 90 - 150 parts of 12-chloro-1-dodecene or 14-chloro-1-tetradecene or 16-chloro-1-hexadecene and dissolve it in 200 - 250 parts of toluene, transfer it to a constant-pressure dropping funnel, and then slowly drop it into the three-necked flask. After the liquid in the constant-pressure dropping funnel is completely dropped, until the reaction is complete, after the reaction is over, the product is soaked and washed in 300 - 400 parts of acetone, and after vacuum filtration under reduced pressure, it is dried in a vacuum oven at a temperature of 40 - 60 °C for 15 - 20 h to obtain the first hydrophobic monomer. The structural formula of the first hydrophobic monomer is: ； By mass fraction, 15 - 27 parts of 10-hydroxydecanoic acid and 5 - 7 parts of cyclopropanol are reacted under esterification reaction conditions. Then, 18 - 25 parts of the above esterification reaction product and 10 - 15 parts of triethylamine are dissolved in 40 - 50 parts of toluene, then transferred into a three-necked flask, and nitrogen is introduced. The three-necked flask is placed in an ice-water bath and the stirring device is started. 8 - 12 parts of acryloyl chloride are dissolved in 15 - 30 parts of toluene, transferred to a constant-pressure dropping funnel, slowly dropped, and after dropping, the reaction is carried out at 0 - 5 °C for 10 - 15 h. After the reaction is over, the product is soaked and washed in 150 - 300 parts of acetone, and after vacuum filtration under reduced pressure, it is dried in a vacuum oven at a temperature of 40 - 60 °C for 10 - 20 h to obtain the second hydrophobic monomer. The structural formula of the second hydrophobic monomer is: 。 2. The shape-complementary salt-resistant hydrophobically associating polyacrylamide for fracturing oil production according to claim 1, wherein: The salt-resistant monomer is one of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylpyrrolidone.

3. A salt-resistant and hydrophobic associating polyacrylamide for shape-complementary fracturing oil production according to claim 1, characterized in that: The complexing agent is one of sodium citrate, sodium ethylenediaminetetraacetate, and diethylenetriaminepentaacetic acid sodium salt. The chain transfer agent is one of sodium hypophosphite and sodium methallylsulfonate. The initiator is one or more of azodiisobutyramidine hydrochloride and azodiisobimidazoline hydrochloride. The oxidizing agent is one of tert-butyl hydroperoxide and ammonium persulfate. The reducing agent is one of ammonium ferrous sulfate and sodium metabisulfite.

4. A preparation method of the salt-resistant and hydrophobic associating polyacrylamide for shape-complementary fracturing oil production as claimed in any one of claims 1 to 3, characterized in that, It includes the following steps: (1) Solution preparation: By mass, 1000 - 1100 parts of pure water, 220 - 280 parts of acrylamide, 50 - 80 parts of acrylic acid, 25 - 45 parts of sodium hydroxide, 5 - 10 parts of urea, 1 - 5 parts of the first hydrophobic monomer, 1 - 4 parts of the second hydrophobic monomer, and 40 - 50 parts of the salt-resistant monomer are mixed and stirred evenly, then frozen to -2 - 0 °C and transferred into a heat preservation kettle; (2) At the 0th minute, nitrogen is introduced into the solution in the reaction kettle to remove oxygen, and 0.001 - 0.002 parts of complexing agent and 0.003 - 0.006 parts of chain transfer agent are added; (3) At the 15th minute, 0.02 - 0.5 parts of initiator are added; (4) At the 20th minute, 0.002 - 0.006 parts of oxidant are added; (5) At the 21st minute, 0.002 - 0.006 parts of reducing agent are added. After the polymerization reaction starts, the nitrogen pipe is removed and nitrogen supply is stopped; (6) After the reaction is complete, it is aged for 1.5 - 2.5 h, and then pelletized, dried, and ground.

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