Shape complementation type salt-resistant hydrophobic association polyacrylamide for fracturing oil extraction and preparation method of shape complementation type salt-resistant hydrophobic association polyacrylamide

Abstract

The invention relates to the field of oilfield chemical fracturing, in particular to shape complementary type salt-resistant hydrophobic association polyacrylamide for fracturing oil extraction and a preparation method thereof, and the shape complementary type salt-resistant hydrophobic association polyacrylamide is prepared from 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. The preparation method comprises the following steps: firstly synthesizing a first hydrophobic monomer and a second hydrophobic monomer, then uniformly mixing and stirring pure water, acrylamide, acrylic acid, sodium hydroxide, urea, the first hydrophobic monomer, the second hydrophobic monomer and a salt-resistant monomer according to certain parts by mass, cooling, sequentially adding a complexing agent, a chain transfer agent, an initiator, an oxidant and a reducing agent, and uniformly stirring to obtain a finished product. After the reaction is finished, a rubber block is granulated, dried and ground, the shape complementary type salt-resistant hydrophobic association polyacrylamide for fracturing oil extraction is obtained, two hydrophobic monomers of the polyacrylamide have a shape complementary effect, and the viscosity of the polyacrylamide in saline water is effectively improved.

Description

Technical Field

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

[0002] With the rapid development of my country's economy, the demand for energy is growing. As an important energy resource, the stable supply of oil is crucial to national energy security. However, in the process of oil extraction, especially for low-permeability oil fields, conventional extraction methods often fail to achieve efficient extraction. Therefore, fracturing technology, as an important means to improve crude oil recovery, has been widely used at home and abroad.

[0003] Fracturing technology is to inject high-pressure liquid into the formation to form cracks, thereby increasing the permeability of the oil layer 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 sand carrying capacity, and reduce friction, and is a key factor in achieving fracturing effects. 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, which affects 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 direction for current fracturing fluid research. In the prior art, hydrophobic associating polyacrylamide is prepared by introducing hydrophobic groups into polyacrylamide molecules to improve their stability in high temperature and high salt environments. In the molecular structure of hydrophobic associating polyacrylamide, hydrophobic groups can form hydrophobic micro-regions, enhance the interaction between molecules, and thus improve the thermal stability and salt resistance of the polymer.

[0004] The synthesis of salt-resistant hydrophobic associating polyacrylamide for fracturing proposed in this patent is intended to solve the viscosity stability problem 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 the fracturing fluid. The present invention provides a shape-complementary salt-resistant hydrophobic associating polyacrylamide for fracturing oil production, and the preparation method comprises the following steps: (1) By weight, 166-222 parts of 1,11-dodecadiene, 1,13-tetradecadiene or 1,15-hexadecadiene are reacted with 8-12 parts of borane and then with 68-102 parts of thionyl chloride for substitution reaction to obtain 12-chloro-1-dodecene, 14-chloro-1-tetradecene or 16-chloro-1-hexadecene. 20-25 parts of tripropylamine or tributylamine are dissolved in 80-100 parts of toluene and then transferred into a three-necked flask and nitrogen is introduced. The three-necked flask was placed in an ice water bath and stirred; 90-150 parts of 12-chloro-1-dodecene or 14-chloro-1-tetradecene or 16-chloro-1-hexadecene were weighed and dissolved in 200-250 parts of toluene, transferred to a constant pressure dropping funnel, and then slowly added dropwise to the three-necked flask until the liquid in the constant pressure dropping funnel was added dropwise until the reaction was complete. After the reaction, the product was placed in 300-400 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at a temperature of 40-60° C. for 15-20 h to obtain a first hydrophobic monomer, and the structural formula of the first hydrophobic monomer is: .

[0006] (2) 15-27 parts of 10-hydroxydecanoic acid and 5-7 parts of cyclopropanol are reacted under esterification reaction conditions, and then 18-25 parts of the above esterification reaction product and 10-15 parts of triethylamine are dissolved in 40-50 parts of toluene, and 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 turned on. 8-12 parts of acryloyl chloride are dissolved in 15-30 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition is completed, the reaction is carried out at 0-5 ℃ for 10-15 hours. After the reaction is completed, the product is placed in 150-300 parts of acetone for soaking and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at 40-60 ℃ for 10-20 hours to obtain the second hydrophobic monomer: .

[0007] (3) Solution preparation: 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, and then frozen to -2-0°C and then transferred to an insulated kettle; (4) At minute 0, nitrogen was introduced into the solution in the reactor to remove oxygen and 0.001-0.002 parts of a complexing agent and 0.003-0.006 parts of a chain transfer agent were added; (5) At 15 minutes, add 0.02-0.5 parts of initiator; (6) At the 20th minute, add 0.002-0.006 parts of oxidant; (7) At 21 minutes, add 0.002-0.006 parts of reducing agent, and after the polymerization reaction starts, remove the nitrogen tube and stop nitrogen flow; (8) After the reaction is complete, mature for 1.5-2.5 h, then granulate, dry and grind.

[0008] The salt-resistant monomer is one of 2-acrylamido-2-methylpropanesulfonic acid and N-vinyl pyrrolidone. The complexing agent is one of sodium citrate, sodium ethylenediaminetetraacetate and sodium diethylenetriaminepentaacetate. The chain transfer agent is one of sodium hypophosphite and sodium methyl propylene sulfonate. The initiator is one or more of azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride. The oxidant is one of tert-butyl hydroperoxide and ammonium persulfate. The reducing agent is one of ammonium ferrous sulfate and sodium pyrosulfite.

[0009] Compared with the prior art, the present invention has the following beneficial effects: the first and second hydrophobic monomers are used in the synthesis, and the two monomers can form a shape complementary effect due to their special shape structure, that is, the first hydrophobic monomer has a claw-like structure that can complement the shape of the three-membered ring structure of the second hydrophobic monomer to a certain extent. The mechanism diagram is shown in the attached Figure 1 , improve the viscosity of hydrophobic associating polyacrylamide in salt water. At the same time, the interaction between the two hydrophobic monomers and the salt resistance of the salt-resistant monomers make the product have good salt resistance and high temperature shear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a diagram of the complementary mechanism of the first and second hydrophobic monomers of the present invention; Figure 2 This is a viscosity test diagram of Example 1 of the present invention in salt water; Figure 3 This is a viscosity test diagram of Example 2 of the present invention in salt water; Figure 4 This is a viscosity test diagram of Example 3 of the present invention in salt water; Figure 5 This is a viscosity test diagram of Example 4 of the present invention in salt water; Figure 6 This is a viscosity test diagram of Example 5 of the present invention in salt water; Figure 7 This is a viscosity test diagram of Example 6 of the present invention in salt water; Figure 8 This is a viscosity test diagram of Comparative Example 1 of the present invention in salt water; Fig. 9 This is a viscosity test diagram of comparative example 2 of the present invention in salt water; Fig.10 The viscosity test diagram after high temperature shearing of Examples 1-6 and Comparative Examples 1-2 of the present invention; Fig.11 It is a test diagram of the sand carrying performance of Examples 1-6 of the present invention and Comparative Examples 1-2. DETAILED DESCRIPTION

[0011] The following are specific embodiments of the present invention, which further describe the operation scheme of the present invention. The protection scope includes but is not limited to these embodiments. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0012] Example 1: A shape-complementary salt-resistant hydrophobic associating polyacrylamide for oil fracturing, the preparation steps of which are as follows: (1) By mass, 166 parts of 1,11-dodecadiene are first reacted with 8 parts of borane and then with 68 parts of dichlorothionyl for substitution reaction to obtain 12-chloro-1-dodecene. 20 parts of tripropylamine are dissolved in 80 parts of toluene, and 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 turned on. 95 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 added to the three-necked flask until the liquid in the constant pressure dropping funnel is added until the reaction is complete. After the reaction is completed, the product is placed in 400 parts of acetone for soaking and cleaning, and then filtered under reduced pressure and dried in a vacuum oven at 50 ° C for 20 h to obtain the first hydrophobic monomer; (2) In terms of mass, 18 parts of 10-hydroxydecanoic acid and 5.6 parts of cyclopropanol were reacted under esterification reaction conditions, 20 parts of the above esterification reaction product and 12 parts of triethylamine were dissolved in 45 parts of toluene, and 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 turned on. 10.2 parts of acryloyl chloride were dissolved in 20 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition was completed, the reaction was carried out at 2°C for 12 hours. After the reaction was completed, the product was placed in 200 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at 50°C for 15 hours to obtain a second hydrophobic monomer; (3) Solution preparation: by weight, 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 were mixed and stirred evenly, then frozen to -2 °C and transferred to a heat preservation kettle; (4) At minute 0, nitrogen was introduced into the solution in the reaction kettle to remove oxygen and 0.0018 parts of sodium diethylenetriamine pentaacetate and 0.004 parts of sodium hypophosphite were added; (5) At 15 minutes, add 0.06 parts of azobisisobutylimidazoline hydrochloride and 0.2 parts of azobisisobutylamidine hydrochloride; (6) At the 20th minute, 0.004 parts of tert-butyl hydroperoxide were added; (7) At the 21st minute, 0.004 parts of ammonium ferrous sulfate was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped; (8) After the reaction is complete, mature for 2 h, then granulate, dry and grind. The reaction formula is as follows: .

[0013] Example 2: A shape-complementary salt-resistant hydrophobic associating polyacrylamide for oil fracturing, the preparation steps of which are as follows: (1) First, 166 parts of 1,11-dodecadiene are added to 8 parts of borane and then substituted with 68 parts of dichlorothionyl to obtain 12-chloro-1-dodecene. 23 parts by mass of tributylamine are dissolved in 80 parts of toluene, and 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 turned on. Weigh 100 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 add it to the three-necked flask until the liquid in the constant pressure dropping funnel is added until the reaction is complete. After the reaction is completed, the product is placed in 400 parts of acetone for soaking and cleaning, and then filtered under reduced pressure and dried in a vacuum oven at 50 ° C for 20 h to obtain the first hydrophobic monomer; (2) In terms of mass, 23 parts of 10-hydroxydecanoic acid and 5 parts of cyclopropanol were reacted under esterification reaction conditions, 22 parts of the above esterification reaction product and 11 parts of triethylamine were dissolved in 45 parts of toluene, and 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 turned on. 11 parts of acryloyl chloride were dissolved in 20 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition was completed, the reaction was carried out at 2°C for 12 hours. After the reaction was completed, the product was placed in 200 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at 50°C for 15 hours to obtain a second hydrophobic monomer; (3) Solution preparation: by weight, 1000 parts 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 were mixed and stirred evenly, then frozen to -2°C and transferred to an insulated kettle; (4) At minute 0, nitrogen was introduced into the solution in the reaction vessel to remove oxygen and 0.0019 parts of sodium diethylenetriamine pentaacetate and 0.0041 parts of sodium hypophosphite were added; (5) At 15 minutes, add 0.065 parts of azobisisobutylimidazoline hydrochloride and 0.22 parts of azobisisobutylamidine hydrochloride; (6) At the 20th minute, 0.0042 parts of ammonium persulfate were added; (7) At the 21st minute, 0.0043 parts of ammonium ferrous sulfate was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped; (8) After the reaction is complete, mature for 2 h, then granulate, dry and grind. The reaction formula is as follows: .

[0014] Example 3: (1) By weight, 194 parts of 1,13-tetradecadiene are first reacted with 10 parts of borane and then with 85 parts of dichlorothionyl for substitution reaction to obtain 14-chloro-1-tetradecene. 21 parts of tripropylamine are dissolved in 80 parts of toluene, and 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 turned on. 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 it dropwise to the three-necked flask until the liquid in the constant pressure dropping funnel is added until the reaction is complete. After the reaction is completed, the product is placed in 400 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at 50 ° C for 20 h to obtain the first hydrophobic monomer; (2) In terms of mass, 25 parts of 10-hydroxydecanoic acid and 6 parts of cyclopropanol were reacted under esterification reaction conditions, 23 parts of the above esterification reaction product and 14 parts of triethylamine were dissolved in 45 parts of toluene, and 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 turned on. 11.5 parts of acryloyl chloride were dissolved in 20 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition was completed, the reaction was carried out at 2°C for 12 hours. After the reaction was completed, the product was placed in 200 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at 50°C for 15 hours to obtain a second hydrophobic monomer; (3) Solution preparation: by weight, 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 were mixed and stirred evenly, then frozen to -2°C and transferred to an insulated kettle; (4) At minute 0, nitrogen was introduced into the solution in the reaction vessel to remove oxygen and 0.0017 parts of sodium diethylenetriamine pentaacetate and 0.0042 parts of sodium hypophosphite were added; (5) At 15 minutes, add 0.065 parts of azobisisobutylimidazoline hydrochloride and 0.23 parts of azobisisobutylamidine hydrochloride; (6) At the 20th minute, 0.004 parts of tert-butyl hydroperoxide were added; (7) At the 21st minute, 0.004 parts of ammonium ferrous sulfate was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped; (8) After the reaction is complete, mature for 2 h, then granulate, dry and grind. The reaction formula is as follows: .

[0015] Example 4: (1) By weight, 194 parts of 1,13-tetradecadiene are first reacted with 10 parts of borane and then with 85 parts of dichlorothionyl for substitution reaction to obtain 14-chloro-1-tetradecene. 25 parts of tributylamine are dissolved in 80 parts of toluene, and 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 turned on. Weigh 115 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 it dropwise to the three-necked flask until the liquid in the constant pressure dropping funnel is added until the reaction is complete. After the reaction is completed, the product is placed in 400 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at 50 ° C for 20 h to obtain the first hydrophobic monomer; (2) In terms of mass, 22.3 parts of 10-hydroxydecanoic acid and 6.2 parts of cyclopropanol were reacted under esterification reaction conditions, 22.5 parts of the above esterification reaction product and 13.8 parts of triethylamine were dissolved in 45 parts of toluene, and 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 turned on. 11.6 parts of acryloyl chloride were dissolved in 20 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition was completed, the reaction was carried out at 2°C for 12 hours. After the reaction was completed, the product was placed in 200 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at 50°C for 15 hours to obtain a second hydrophobic monomer; (3) Solution preparation: by weight, 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 were mixed and stirred evenly, then frozen to -2°C and transferred to an insulated kettle; (4) At minute 0, nitrogen was introduced into the solution in the reaction vessel to remove oxygen and 0.0018 parts of sodium diethylenetriamine pentaacetate and 0.0045 parts of sodium hypophosphite were added; (5) At 15 minutes, add 0.067 parts of azobisisobutylimidazoline hydrochloride and 0.23 parts of azobisisobutylamidine hydrochloride; (6) At the 20th minute, 0.0045 parts of tert-butyl hydroperoxide were added; (7) At 21 minutes, 0.0045 parts of sodium metabisulfite was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped. (8) After the reaction is complete, mature for 2 h, then granulate, dry and grind. The reaction formula is as follows: .

[0016] Example 5: (1) By mass, 222 parts of 1,15-hexadecadiene are first reacted with 12 parts of borane and then with 102 parts of dichlorothionyl for substitution reaction to obtain 16-chloro-1-hexadecene. 25 parts of tripropylamine are dissolved in 80 parts of toluene, and 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 turned on. 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 add it dropwise to the three-necked flask until the liquid in the constant pressure dropping funnel is added until the reaction is complete. After the reaction is completed, the product is placed in 300-400 parts of acetone for soaking and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at 50 ° C for 20 h to obtain the first hydrophobic monomer; (2) In terms of mass, 25.3 parts of 10-hydroxydecanoic acid and 6.3 parts of cyclopropanol were reacted under esterification reaction conditions, 24.5 parts of the above esterification reaction product and 13.8 parts of triethylamine were dissolved in 45 parts of toluene, and 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 turned on. 10.6 parts of acryloyl chloride were dissolved in 20 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition was completed, the reaction was carried out at 2°C for 12 hours. After the reaction was completed, the product was placed in 200 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at 50°C for 15 hours to obtain a second hydrophobic monomer; (3) Solution preparation: by weight, 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 were mixed and stirred evenly, then frozen to -2°C and transferred to a heat preservation kettle; (4) At minute 0, nitrogen was introduced into the solution in the reaction kettle to remove oxygen and 0.0018 parts of sodium diethylenetriamine pentaacetate and 0.0043 parts of sodium hypophosphite were added; (5) At 15 minutes, add 0.058 parts of azobisisobutylimidazoline hydrochloride and 0.25 parts of azobisisobutylamidine hydrochloride; (6) At the 20th minute, 0.0043 parts of ammonium persulfate was added; (7) At the 21st minute, 0.0043 parts of ammonium ferrous sulfate was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped; (8) After the reaction is complete, mature for 2 h, then granulate, dry and grind. The reaction formula is as follows: .

[0017] Example 6: (1) By mass, 222 parts of 1,15-hexadecadiene are first reacted with 12 parts of borane and then with 102 parts of dichlorothionyl for substitution reaction to obtain 16-chloro-1-hexadecene. 24 parts of tributylamine are dissolved in 80 parts of toluene, and 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 turned on. 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 then slowly add it dropwise to the three-necked flask until the liquid in the constant pressure dropping funnel is added until the reaction is complete. After the reaction is completed, the product is placed in 400 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at 50 ° C for 20 h to obtain the first hydrophobic monomer; (2) In terms of mass, 23.7 parts of 10-hydroxydecanoic acid and 6.1 parts of cyclopropanol were reacted under esterification reaction conditions, 22.7 parts of the above esterification reaction product and 11.5 parts of triethylamine were dissolved in 45 parts of toluene, and 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 turned on. 11.3 parts of acryloyl chloride were dissolved in 20 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition was completed, the reaction was carried out at 2°C for 12 hours. After the reaction was completed, the product was placed in 200 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at 50°C for 15 hours to obtain a second hydrophobic monomer; (3) Solution preparation: by weight, 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-vinyl pyrrolidone were mixed and stirred evenly, then frozen to -2 °C and transferred to a heat preservation kettle; (4) At minute 0, nitrogen was introduced into the solution in the reaction kettle to remove oxygen and 0.0018 parts of sodium diethylenetriamine pentaacetate and 0.0047 parts of sodium hypophosphite were added; (5) At 15 minutes, add 0.07 parts of azobisisobutylimidazoline hydrochloride and 0.19 parts of azobisisobutylamidine hydrochloride; (6) At the 20th minute, 0.0044 parts of tert-butyl hydroperoxide were added; (7) At the 21st minute, 0.0044 parts of ammonium ferrous sulfate was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped; (8) After the reaction is complete, mature for 2 h, then granulate, dry and grind. The reaction formula is as follows: .

[0018] Comparative Example 1: (1) In terms of mass fractions, 20 parts of 10-hydroxydecanoic acid and 5 parts of cyclopropanol were reacted under esterification reaction conditions, 20 parts of the above esterification reaction product and 12 parts of triethylamine were dissolved in 45 parts of toluene, and 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 turned on. 10 parts of acryloyl chloride were dissolved in 20 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition was completed, the reaction was carried out at 2°C for 12 hours. After the reaction was completed, the product was placed in 200 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it was dried in a vacuum oven at 50°C for 15 hours to obtain a hydrophobic monomer; (2) Solution preparation: by weight, 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 hydrophobic monomer, and 45 parts of 2-acrylamido-2-methylpropanesulfonic acid were mixed and stirred evenly, then frozen to -2 °C and transferred to a heat preservation kettle; (3) At minute 0, nitrogen was introduced into the solution in the reaction kettle to remove oxygen and 0.0019 parts of sodium diethylenetriamine pentaacetate and 0.0042 parts of sodium hypophosphite were added; (4) At 15 minutes, add 0.07 parts of azobisisobutylimidazoline hydrochloride and 0.22 parts of azobisisobutylamidine hydrochloride; (5) At the 20th minute, 0.0045 parts of tert-butyl hydroperoxide were added; (6) At the 21st minute, 0.0045 parts of ammonium ferrous sulfate was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped; (7) After the reaction is complete, mature for 2 h, then granulate, dry and grind.

[0019] Comparative Example 2: (1) By mass, 222 parts of 1,15-hexadecadiene are first added to 10 parts of borane and then substituted with 85 parts of dichlorothionyl to obtain 16-chloro-1-hexadecene. 20 parts of tripropylamine are dissolved in 80 parts of toluene, and 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 turned on. Weigh 100 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 add it dropwise to the three-necked flask until the liquid in the constant pressure dropping funnel is added until the reaction is complete. After the reaction is completed, the product is placed in 400 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at 50 ° C for 20 h to obtain a hydrophobic monomer; (2) Solution preparation: by weight, 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 preservation kettle; (3) At minute 0, nitrogen was introduced into the solution in the reaction kettle to remove oxygen and 0.0018 parts of sodium diethylenetriamine pentaacetate and 0.0045 parts of sodium hypophosphite were added; (4) At 15 minutes, add 0.055 parts of azobisisobutylimidazoline hydrochloride and 0.28 parts of azobisisobutylamidine hydrochloride; (5) At the 20th minute, 0.0035 parts of tert-butyl hydroperoxide were added; (6) At the 21st minute, 0.0035 parts of ammonium ferrous sulfate was added. After the polymerization reaction started, the nitrogen tube was removed and the nitrogen flow was stopped; (7) After the reaction is complete, mature for 2 h, then granulate, dry and grind.

[0020] Test example: Examples 1-6 and Comparative Examples 1-2 were subjected to performance evaluation.

[0021] (1) Thickening: Prepare brine: Accurately weigh 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, and then dissolve and dilute to 2 L with pure water to obtain brine with a mineralization degree of 40,000.

[0022] The samples of Examples 1-6 and Comparative Examples 1-2 were 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% respectively with 40000 degree of mineralization salt water. The viscosity was measured after stirring for 5 minutes. The specific results are shown in the attached Figure 2-9 As shown, the results show that for Examples 1-6, the two hydrophobic monomers have a shape complementation effect due to their special shapes, that is, the claw structure of the first hydrophobic monomer can interact with the ring structure of the second hydrophobic monomer and combine together, and the two monomers can also form a hydrophobic association, so the viscosity of the polymer in salt water can be significantly improved, while Comparative Examples 1-2 only rely on the first or second hydrophobic monomer to participate in the association, and the effect is lower than that of the Examples. In solutions with a concentration of more than 0.55%, the viscosity of Examples 1-6 and Comparative Examples 1 or 2 is increased by more than 50%.

[0023] (2) Viscosity and retention rate at high temperature: In order to balance viscosity and solubility, the samples of Examples 1-6 and Comparative Examples 1-2 were prepared into 0.4% mass fraction solutions with 40,000 salinity brine, and the viscosity of each solution was measured at 120 °C, 170 s -1 The viscosity after shearing for 60 min at a speed of Fig.10 The results show that the polymer solutions of Examples 1-6 have better high temperature shear resistance under the effects of hydrophobic association and shape complementation than the comparative example.

[0024] (3) Sand carrying performance: Weigh 0.8 g of the samples of Examples 1-6 and Comparative Examples 1-2 respectively and dissolve them in 199.2 g of brine. After dissolution, let it stand for 30 min. Take 100 mL and place it in a 250 mL beaker. Add 25 mL of fine sand (20-40 mesh) and stir evenly. Transfer it to a measuring cylinder and observe and record the sedimentation rate of the fine sand. The specific results are shown in the attached Fig.11 The results show that Examples 1-6 have better association and shape complementation, which makes them have better sand carrying capacity, while Comparative Example 1-2 has weaker association and no good sand carrying capacity.

Claims

1. A shape-complementary salt-resistant hydrophobic associating polyacrylamide for oil fracturing, 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 oxidant and a reducing agent; By weight, 166-222 parts of 1,11-dodecadiene, 1,13-tetradecadiene or 1,15-hexadecadiene are reacted with 8-12 parts of borane and then with 68-102 parts of thionyl chloride for substitution reaction to obtain 12-chloro-1-dodecene, 14-chloro-1-tetradecene or 16-chloro-1-hexadecene. 20-25 parts of tripropylamine or tributylamine are dissolved in 80-100 parts of toluene, and then transferred into a three-necked flask, and nitrogen is introduced to the flask to remove the tripropylamine. The flask is placed in an ice water bath and stirred; 90-150 parts of 12-chloro-1-dodecene or 14-chloro-1-tetradecene or 16-chloro-1-hexadecene are weighed and dissolved in 200-250 parts of toluene, transferred to a constant pressure dropping funnel, and then slowly added dropwise to the three-necked flask, until the liquid in the constant pressure dropping funnel is added dropwise until the reaction is complete, after the reaction is completed, the product is placed in 300-400 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at a temperature of 40-60° C. for 15-20 h to obtain a first hydrophobic monomer, and 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, and then 18-25 parts of the above esterification reaction product and 10-15 parts of triethylamine are dissolved in 40-50 parts of toluene, and then transferred to a three-necked flask, and nitrogen is introduced, the three-necked flask is placed in an ice water bath, and a stirring device is turned on; 8-12 parts of acryloyl chloride are dissolved in 15-30 parts of toluene, transferred to a constant pressure dropping funnel, and slowly added dropwise. After the addition is completed, the reaction is carried out at 0-5°C for 10-15 hours. After the reaction is completed, the product is placed in 150-300 parts of acetone for immersion and cleaning, and after reduced pressure filtration, it is dried in a vacuum oven at a temperature of 40-60°C for 10-20 hours to obtain a second hydrophobic monomer. The structural formula of the second hydrophobic monomer is: .

2. The shape-complementary salt-resistant hydrophobic associating polyacrylamide for oil fracturing according to claim 1, characterized in that: The salt-resistant monomer is one of 2-acrylamide-2-methylpropanesulfonic acid and N-vinyl pyrrolidone.

3. The shape-complementary salt-resistant hydrophobic associating polyacrylamide for oil fracturing according to claim 1, characterized in that: The complexing agent is one of sodium citrate, sodium ethylenediaminetetraacetate, and sodium diethylenetriaminepentaacetate; the chain transfer agent is one of sodium hypophosphite and sodium methyl methacrylate sulfonate; the initiator is one or more of azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride; the oxidant is one of tert-butyl hydroperoxide and ammonium persulfate; and the reducing agent is one of ferrous ammonium sulfate and sodium pyrosulfite.

4. A method for preparing the salt-resistant hydrophobic associating polyacrylamide for oil fracturing with complementary shapes of any shape according to claims 1 to 3, characterized in that: The steps include: (1) Solution preparation: by weight, 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, and then frozen to -2-0°C and then transferred to an insulated kettle; (2) At minute 0, nitrogen was introduced into the solution in the reactor to remove oxygen and 0.001-0.002 parts of a complexing agent and 0.003-0.006 parts of a chain transfer agent were added; (3) At 15 minutes, add 0.02-0.5 parts of initiator; (4) At the 20th minute, add 0.002-0.006 parts of oxidant; (5) At 21 minutes, add 0.002-0.006 parts of reducing agent, and after the polymerization reaction starts, remove the nitrogen tube and stop nitrogen flow; (6) After the reaction is complete, mature for 1.5-2.5 hours, then granulate, dry and grind.

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