A shear-resistant, high-drag-reducing, high-viscosity slippery water drag reducer and preparation method thereof

Abstract

The invention discloses a shear-resistant, high-drag-reducing, high-viscosity slippery water drag reducer and a preparation method thereof, and belongs to the field of deep well / extra-deep well volume fracturing. The drag reducer is polymerized by acrylamide, sodium acrylate, a sulfonate ion-containing hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight grading agent and a composite initiator. Through the special sulfonate ion-containing hydrophobic monomer, the hydrophobic unit microblock regulator matched with the hydrophobic monomer and the polymer molecular weight control, the polymer solubility and viscosity-increasing performance are significantly improved; the shear degradation resistance of the drag reducer is improved; the drag reducer has excellent sand carrying performance and drag reduction performance; the shortcomings of the existing slippery water drag reducer, such as weak shear resistance, fast drag reduction rate drop, and poor sand carrying performance, are overcome, and the special requirements of deep / ultra-deep oil and gas reservoir fracturing on the rheology of fracturing fluid are met, key material support is provided for the development of deep / ultra-deep oil and gas resources, and the efficient development goal of deep / ultra-deep oil and gas resources is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of deep well / ultra-deep well volume fracturing, and in particular to a shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer and a preparation method thereof. Background Art

[0002] In the process of hydraulic fracturing of unconventional oil and gas reservoirs, in order to increase the sand ratio of fracturing fluid, high-viscosity slippery water (10-20mPa.s) is increasingly used. Compared with medium and low-viscosity slippery water, high-viscosity slippery water has better sand-carrying performance. The existing high-viscosity slippery water drag reducer (thickener) is mainly high molecular weight polyacrylamide, and the molecular weight is often greater than 25 million or even more than 30 million. The increase in its viscosity leads to a decrease in drag reduction performance, and the increase in molecular weight leads to a decrease in the shear resistance of the polymer. For the fracturing of deep / ultra-deep oil and gas reservoirs, the drag reducer (thickener) agent also faces a longer shear time, more prominent shear degradation, and more serious loss of drag reduction performance and sand-carrying performance. Therefore, improving the drag reduction, sand-carrying and shear resistance of the viscous slippery water drag reducer (thickener) agent is the primary task that needs to be solved in the development of high-viscosity slippery water. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art, and to provide a shear-resistant, high-drag-reducing, high-viscosity slickwater drag reducer and a preparation method thereof. The drag reducer is prepared by polymerization of acrylamide, sodium acrylate (or prepared by post-hydrolysis of acrylamide), a sulfonate ion-containing hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight regulator and a composite initiator. The present invention can significantly improve the polymer solubility and viscosity-increasing properties through the control of special sulfonate ion-containing hydrophobic monomers, hydrophobic unit microblock regulators matched with the hydrophobic monomers and polymer molecular weight; improve the shear degradation resistance of the drag reducer; have excellent sand carrying performance and drag reduction performance; overcome the shortcomings of existing drag reducers such as weak shear resistance, fast drag reduction rate drop, and poor sand carrying performance, and can meet the special requirements of deep / ultra-deep oil and gas reservoir fracturing on fracturing fluid rheology and "high wellbore drag reduction". The invention provides key material support for the development of deep / ultra-deep oil and gas resources and ensures the goal of efficient development of deep / ultra-deep oil and gas resources.

[0004] In order to achieve the above technical effects, the following technical solutions are adopted:

[0005] A shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer, which is formed by hydrolysis after polymerization of acrylamide, a sulfonate-containing ion-type hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight regulator and a composite initiator, i.e., a post-hydrolysis process; or formed by polymerization of acrylamide, sodium acrylate, a sulfonate-containing ion-type hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight regulator and a composite initiator, i.e., a copolymerization process;

[0006] The molecular structure of the drag reducer is:

[0007] ;

[0008] Wherein, x, y, z are the number of each repeating unit;

[0009] In the post-hydrolysis process, the molar ratio of acrylamide to the sulfonate ion-containing hydrophobic monomer is 1: 0.003-0.005;

[0010] In the copolymerization process, the molar ratio of acrylamide, sodium acrylate, and sulfonate-containing ion-type hydrophobic monomer is 1: 0.2-0.4: 0.003-0.005;

[0011] The mass ratio of the hydrophobic unit microblock regulator to the sulfonate ion-containing hydrophobic monomer is 4:1-2:1;

[0012] The mass ratio of molecular weight regulator to reaction system is 0.0075%-0.01%;

[0013] The mass ratio of the composite initiator to the reaction system is 0.0115%-0.0225%;

[0014] After the polymerization reaction is completed in the post-hydrolysis process, sodium hydroxide is used for post-hydrolysis, and the molar ratio of acrylamide monomer to sodium hydroxide is 1:0.2-0.4;

[0015] The structural formula of the sulfonate ion-containing hydrophobic monomer is:

[0016] ;

[0017] Wherein, the R group is a C14 alkyl group or a C16 alkyl group;

[0018] The hydrophobic unit microblock regulator is one or more of AEO-7, AEO-9, OP-8, and OP-10;

[0019] The molecular weight regulator is one or more of sodium formate, sodium hypophosphite, and n-butyl mercaptan;

[0020] The composite initiator is a multi-element initiator, which is composed of an inorganic oxidant, an organic oxidant, a reducing agent, and a water-soluble azo initiator. The inorganic oxidant is a persulfate, and the addition amount is 0.002-0.004% of the reaction system; the organic oxidant is an organic hydrogen peroxide, and the addition amount is 0.001-0.003% of the reaction system; the reducing agent is a sulfite and a bisulfite, and the addition amount is 0.0075-0.0125% of the reaction system; the addition amount of the water-soluble azo initiator is 0.001-0.003% of the reaction system.

[0021] Furthermore, the molecular weight of the drag reducer is in the range of 20-25 million.

[0022] Furthermore, the inorganic oxidant is ammonium persulfate, sodium persulfate, potassium persulfate, or hydrogen peroxide; and the organic oxidant is one or more of tert-butyl hydroperoxide and cumene hydroperoxide.

[0023] Furthermore, the reducing agent is one of sodium sulfite, sodium bisulfite and sodium metabisulfite.

[0024] Furthermore, the water-soluble azo initiator is one of 2,2-azo(2-(2-imidazolin-2-yl)propane) dihydrochloride, 2,2-azo(2-methyl-N-(2-hydroxyethyl)acrylamide), and 2,2-azobis(2-methylpropane) hydrochloride.

[0025] Furthermore, the composite initiator is tert-butyl hydroperoxide, ammonium persulfate, sodium bisulfite, and 2,2-azo(2-(2-imidazoline-2-yl)propane) dihydrochloride.

[0026] Furthermore, the preparation method of the sulfonate ion-containing hydrophobic monomer is:

[0027] Step S1: in a three-necked flask equipped with a magnetic stirrer, a reflux cold flow tube, a thermometer, and two constant pressure dropping funnels, tetradecylamine or hexadecylamine and a catalyst are added in sequence, 2-sodium bromoethylsulfonate or 2-sodium chloroethylsulfonate solution is added to one of the constant pressure dropping funnels, and NaOH solution is added to the other constant pressure dropping funnel; by adjusting the dropping speed of the NaOH solution, the pH value of the reaction is controlled, and the reaction is carried out at a temperature of 50-70° C. for 6-9 hours; after the reaction is completed, a precipitate is precipitated in ethanol, and filtered to obtain an intermediate sodium 2-tetradecylaminoethanesulfonate or sodium 2-hexadecylaminoethanesulfonate;

[0028] Step S2: The intermediate prepared in step S1 is dissolved in dichloromethane and Na 2 CO 3 as an acid-binding agent; acryloyl chloride is added dropwise from a constant pressure dropping funnel, the temperature is controlled at 15-20°C, and after reacting for 18-24 hours, dichloromethane is removed by reduced pressure distillation, and then recrystallization is performed using ethanol to obtain the target monomer, which is a sulfonate ion-containing hydrophobic monomer.

[0029] Further, in step S1, the molar ratio of tetradecylamine or hexadecylamine to sodium 2-bromoethylsulfonate or sodium 2-chloroethylsulfonate is 1:0.8-1:0.9; the catalyst is tetrabutylammonium bromide, and its content is 1% of the mass of tetradecylamine or hexadecylamine; during the reaction, the dropping speed of the NaOH solution is adjusted according to the pH change to control the pH value at 9-12; in step S2, the intermediate, Na 2 CO 3, the molar ratio of acryloyl chloride is 1:3:3.

[0030] A method for preparing a shear-resistant, high-drag-reducing, high-viscosity slippery water drag reducer, the preparation method using a post-hydrolysis process or a copolymerization process:

[0031] Among them, the post-hydrolysis process is detailed as follows:

[0032] The acrylamide monomer and the sulfonate ion-containing hydrophobic monomer are added according to the formula ratio, and ultrapure water is used to prepare a mixed solution with a total monomer mass concentration of 20-35%; the hydrophobic unit microblock regulator and the molecular weight regulator are added to the mixed solution, and then the pH value of the solution is adjusted to 7.0-9.0, and the system temperature is lowered to 0-5°C and then a water-soluble azo initiator and a reducing agent are added; nitrogen is introduced and stirred for 30-40 minutes, and then an oxidant is added, and adiabatic polymerization is carried out for 3-8 hours. After the adiabatic polymerization is completed, granulation, hydrolysis, drying, and crushing are carried out to obtain a target polymer.

[0033] The copolymerization process is detailed as follows:

[0034] The acrylamide monomer, sodium acrylate and sulfonate ion-containing hydrophobic monomer are added according to the formula ratio, and ultrapure water is used to prepare a mixed solution with a total monomer mass concentration of 20-35%; after adjusting the pH to 7.0 with sodium hydroxide, a hydrophobic unit microblock regulator and a molecular weight regulator are added to the mixed solution, and then the pH value of the solution is adjusted to 7.0-9.0, and a water-soluble azo initiator and a reducing agent are added after the system temperature is reduced to 0-5°C; nitrogen is introduced and stirred for 30-40 minutes, and then an oxidant is added, and adiabatic polymerization is carried out for 3-8 hours. After the adiabatic polymerization is completed, granulation, drying and crushing are carried out to obtain a target polymer.

[0035] Furthermore, the pH value of the solution is adjusted by sodium hydroxide and acetic acid; after the addition of the hydrophobic unit microblock regulator, the pH value of the solution is 8.0-8.5; the system temperature is 0° C.; and the thermal insulation polymer time is 5-7 hours.

[0036] The invention discloses a shear-resistant high-drag-reduction and high-viscosity slippery water drag reducer and a preparation method thereof. The drag reducer is prepared by polymerization reaction of acrylamide, sodium acrylate, a sulfonate ion-containing hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight regulator and a composite initiator. The invention cooperates with each other through special sulfonate ion-containing hydrophobic monomers, a hydrophobic unit microblock regulator matched with the hydrophobic monomer and the control of polymer molecular weight, and synergistic polymerization is achieved. Several polymer substances act together to synthesize a polymer molecular structure that is different from the prior art. The difference in molecular structure and the superiority of the molecular structure can significantly improve the polymer solubility and viscosity-increasing performance; improve the shear degradation resistance of the drag reducer; have excellent sand carrying performance and drag reduction performance; overcome the shortcomings of the existing drag reducer such as weak shear resistance, fast drag reduction rate drop, and poor sand carrying performance, and can meet the special requirements of deep / ultra-deep oil and gas reservoir fracturing on fracturing fluid rheology and "high wellbore drag reduction". The invention provides key material support for the development of deep / ultra-deep oil and gas resources and ensures the goal of efficient development of deep / ultra-deep oil and gas resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings in the following description are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0038] Figure 1 is the H of the sulfonate ion type hydrophobic monomer in the embodiment of the present invention. 1 - NMR spectra;

[0039] Figure 2 It is the HPLC-MS chart of the sulfonate ion type hydrophobic monomer in the embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0043] First, a sulfonate ion-containing hydrophobic monomer is synthesized, and the preparation method thereof is as follows:

[0044] Step S1: In a three-necked flask equipped with a magnetic stirrer, a reflux cold flow tube, a thermometer, and two constant pressure dropping funnels, tetradecylamine or hexadecylamine and a catalyst (tetrabutylammonium bromide) are added in sequence, 2-bromoethyl sodium sulfonate or 2-chloroethyl sodium sulfonate solution is added to one of the constant pressure funnels, and NaOH solution is added to the other constant pressure dropping funnel; the pH value of the reaction is controlled by adjusting the dropping speed of the NaOH solution, and the reaction is carried out at a temperature of 50-70° C. for 6-9 hours; after the reaction is completed, a precipitate is precipitated in ethanol, and filtered to obtain an intermediate sodium 2-tetradecylaminoethanesulfonate or sodium 2-hexadecylaminoethanesulfonate;

[0045] In the step S1, the molar ratio of tetradecylamine or hexadecylamine to sodium 2-bromoethylsulfonate or sodium 2-chloroethylsulfonate solution is 1:0.8-1:0.9; the catalyst is tetrabutylammonium bromide, and its content is 1% of the mass of tetradecylamine or hexadecylamine; and the pH value is controlled between 9 and 12 by controlling the dripping speed of the sodium hydroxide solution.

[0046] Step S2: The intermediate prepared in step S1 is dissolved in dichloromethane and Na 2 CO 3 as an acid-binding agent; acryloyl chloride was added dropwise from a constant pressure dropping funnel, the temperature was controlled at 20°C, and after reacting for 18 hours, distillation under reduced pressure was performed to remove dichloromethane, and then recrystallization was performed using ethanol to obtain the target monomer, which is a sulfonate ion-containing hydrophobic monomer (R group is a C16 or C14 alkyl group); in the step S2, the intermediate, Na 2 CO 3 , the molar ratio of acryloyl chloride is 1:3:3.

[0047] The obtained H containing sulfonate ion type hydrophobic monomer (R group is C14 alkyl) 1 -NMR images Figure 1 As shown; the HPLC-MS diagram of the hydrophobic monomer containing sulfonate ions (R group is C14 alkyl) is as follows Figure 2 shown.

[0048] Example 1

[0049] Acrylamide monomer, sodium acrylate monomer, and sulfonate ion-containing hydrophobic monomer (R group is C16 alkyl) are added in a ratio of 1:0.3:0.004, and ultrapure water is used to prepare a mixed solution with a total monomer mass concentration of 25%; after adjusting the pH to 7.0 with sodium hydroxide, a hydrophobic unit microblock regulator AEO-7 is added to the mixed solution in an amount such that the mass ratio of the hydrophobic unit microblock regulator to the sulfonate ion-containing hydrophobic monomer is 3:1, and a molecular weight regulator is added 100ppm of sodium formate, then use sodium hydroxide and acetic acid to adjust the solution pH to 8.0, adjust the system temperature to 0°C, add 100ppm of sodium bisulfite, 30ppm of ammonium persulfate, 10ppm of azo initiator 2,2-azo (2- (2-imidazoline-2-yl) propane) dihydrochloride, add 20ppm of tert-butyl hydroperoxide after nitrogen is introduced and stirred for 30 minutes, and adiabatic polymerization is performed for 3-8h. After the adiabatic polymerization is completed, granulation, drying and crushing are performed to obtain the target polymer. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 1 is tested and calculated according to GB / T 12005.10-92 using an Ubbelohde viscometer (0.55mm diameter) to be 23 million.

[0050] Example 2

[0051] The method of Example 1 was followed, except that acrylamide monomer, sodium acrylate monomer, and sulfonate ion-containing hydrophobic monomer were added in a ratio of 1:0.2:0.004. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 2 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T12005.10-92, and was 22.4 million.

[0052] Example 3

[0053] The method of Example 1 was followed, except that acrylamide monomer, sodium acrylate monomer, and sulfonate ion-containing hydrophobic monomer were added in a ratio of 1:0.4:0.004. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 3 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T12005.10-92, and was 22.6 million.

[0054] Example 4

[0055] The method of Example 1 was followed, except that acrylamide monomer, sodium acrylate monomer, and sulfonate ion-containing hydrophobic monomer were added in a ratio of 1:0.3:0.003. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 4 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T12005.10-92, and was 21.8 million.

[0056] Example 5

[0057] The method of Example 1 was followed, except that acrylamide monomer, sodium acrylate monomer, and sulfonate ion-containing hydrophobic monomer were added in a ratio of 1:0.3:0.005. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 5 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T12005.10-92, and was 21.5 million.

[0058] Example 6

[0059] The method of Example 1 was followed, except that the mass ratio of the hydrophobic unit microblock regulator to the hydrophobic monomer was 4: 1. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 6 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92, and the result was 22.1 million.

[0060] Example 7

[0061] The method of Example 1 was followed, except that the mass ratio of the hydrophobic unit microblock regulator to the hydrophobic monomer was 2: 1. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 7 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92, and the result was 23.1 million.

[0062] Example 8

[0063] The method of Example 1 was followed, except that the hydrophobic unit microblock regulator was replaced with OP-8. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 8 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92, and the result was 22.7 million.

[0064] Example 9

[0065] The method of Example 1 was followed, except that the hydrophobic unit microblock regulator was replaced with OP-10. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 9 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92, and the result was 22.9 million.

[0066] Example 10

[0067] The method of Example 1 was followed, except that the hydrophobic unit microblock regulator was replaced with AEO-9. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 10 was measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92, and was 22.5 million.

[0068] Embodiment 11

[0069] The acrylamide monomer and the sulfonate ion-containing hydrophobic monomer (R group is a C16 alkyl) were added in a ratio of 1:0.004, and ultrapure water was used to prepare a mixed solution with a total monomer mass concentration of 25%; the hydrophobic unit microblock regulator AEO-7 was added to the mixed solution, and the added amount was a hydrophobic unit microblock regulator and a sulfonate ion-containing hydrophobic monomer mass ratio of 3:1, and 100ppm of sodium formate, a molecular weight regulator, was added, and then sodium hydroxide and acetic acid were used to adjust the solution pH to 8.0 , after adjusting the system temperature to 0°C, add 100ppm of sodium bisulfite, 30ppm of ammonium persulfate, 10ppm of azo initiator 2,2-azo (2- (2-imidazoline-2-yl) propane) dihydrochloride, add 20ppm of tert-butyl hydroperoxide after nitrogen is introduced and stirred for 30 minutes, and adiabatic polymerization is performed for 3-8h. After the adiabatic polymerization is completed, granulation, hydrolysis (adding sodium hydroxide with a molar mass of 30% of acrylamide, sealed and hydrolyzed at 90°C for 2 hours), drying, and crushing are performed to obtain the target polymer. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Example 11 is tested and calculated according to GB / T12005.10-92 using an Ubbelohde viscometer (0.55mm diameter) to be 22.6 million.

[0070] Comparative Example 1

[0071] The method of Example 1 was followed, except that the R group of the sulfonate ion hydrophobic monomer was a C12 alkyl group. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 1 was 23.2 million, as measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92.

[0072] Comparative Example 2

[0073] The method of Example 1 was followed, except that the R group of the sulfonate ion hydrophobic monomer was a C18 alkyl group. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 2 was 22.8 million, as measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92.

[0074] Comparative Example 3

[0075] The method of Example 1 was followed, except that the hydrophobic monomer was dimethyl hexadecyl allyl ammonium chloride. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 3 was 21.9 million, as measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92.

[0076] Comparative Example 4

[0077] The method of Example 1 was followed, except that the mass ratio of the microblock regulator to the hydrophobic monomer was 5: 1. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 4 was tested and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92, and the result was 22.3 million.

[0078] Comparative Example 5

[0079] The method of Example 1 was followed, except that the mass ratio of the microblock regulator to the hydrophobic monomer was 1:2. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 5 was 22.5 million, as measured and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92.

[0080] Comparative Example 6

[0081] The method of Example 1 was followed, except that the amount of the molecular weight modifier sodium formate was increased to 175 ppm. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 6 was tested and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92 and was 18 million.

[0082] Comparative Example 7

[0083] The method of Example 1 was followed, except that the amount of sodium formate, a molecular weight modifier, was reduced by 50 ppm. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 7 was tested and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92 and was 27 million.

[0084] Comparative Example 8

[0085] The method of Example 1 was followed, except that the microblock regulator was replaced with AEO-5. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 8 was 22.5 million, as measured by an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92.

[0086] Comparative Example 9

[0087] The method of Example 1 was followed, except that the microblock regulator was replaced with OP-7. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 9 was 22.1 million, as measured by an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92.

[0088] Comparative Example 10

[0089] The method of Example 1 was followed, except that the microblock regulator was replaced with OP-13. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 10 was 22.3 million, as measured by an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92.

[0090] Comparative Example 11

[0091] The method of Example 1 was followed, except that no block grader was added. The viscosity average molecular weight of the high temperature resistant and salt resistant instant fracturing fluid thickener obtained in Comparative Example 11 was tested and calculated using an Ubbelohde viscometer (0.55 mm diameter) according to GB / T 12005.10-92 and was 22.2 million.

[0092] Comparative Example 12

[0093] The method of Example 1 was followed, except that no azo component was added to the initiator. The reaction failed, the colloid was very soft, and a large amount of unpolymerized liquid was present.

[0094] Comparative Example 13

[0095] The method of Example 1 was followed, except that ammonium persulfate was not added as the initiator. The reaction failed, the temperature was not raised further after reaching 20°C, a large amount of monomers were not polymerized, and the reaction failed.

[0096] Comparative Example 14

[0097] The method of Example 1 was followed, except that no tert-butyl hydroperoxide was added as the initiator. The reaction could not be initiated and the polymerization failed.

[0098] Comparative Example 15

[0099] The mainstream high molecular weight drag reducer on the market is partially hydrolyzed polyacrylamide, with a molecular weight of 30 million and a degree of hydrolysis of 30%.

[0100] The polymer solution performance evaluation method is as follows:

[0101] (1) Adhesion time test

[0102] 400 mL of clean water was added to 1000 mL beakers respectively. At a stirring speed of 500 r / min, 0.05% (500 ppm) of the sample was added respectively. The viscosity-increasing time (glass rod can be drawn) after adding the thickener was recorded. The details are shown in Table 1.

[0103] (2) Viscosity test

[0104] Stir in clean water at 25°C and 500 r / min for 3 min and measure with a six-speed viscometer for 170 s -1 The viscosity of the samples was divided into concentrations from 500 ppm to 1200 pmm, and then the concentrations corresponding to the viscosities of 10 mPa·s and 20 mPa·s of each sample were found through fitting and concentration adjustment. The results are shown in Table 1.

[0105] Table 1 The tack time of the samples and the corresponding concentrations at 10 mPa·s and 20 mPa·s

[0106]

[0107] Comparative polymers that failed to meet the standards in the tack build test and tack time test were not evaluated for other properties.

[0108] (3) Drag reduction rate

[0109] The drag reduction rate of the test embodiment is carried out in accordance with the provisions of Chapter 7.8 of SY-T 7627-2021 for determining the drag reduction rate, and the 5-min drag reduction rate data is taken as the drag reduction rate value, as shown in Table 2.

[0110] Table 2 Drag reduction rate corresponding to sample viscosity of 10mPa·s and 20mPa·s

[0111]

[0112] (4) Sand carrying performance

[0113] Take 1000 mL of the target solution and prepare about 400 mL. Stir at 500 r / min for 3 min during sample preparation. Pour 100 mL of the test solution into a 100 mL measuring cylinder, and then test the sedimentation rate of 20 / 40 mesh ceramsite in the measuring cylinder. Repeat the test of the sedimentation rate of 20 ceramsite particles, and then take the average value, as shown in Table 3.

[0114] Table 3 Sedimentation velocity corresponding to sample viscosity of 10mPa·s and 20mPa·s

[0115]

[0116] (5) Shear resistance

[0117] Prepare about 400 mL of the target solution in a 1000 mL beaker. Stir at 500 r / min for 3 min. Take 300 mL of the test solution and measure it for 170 s using a six-speed rotational viscometer. -1The viscosity value (mP a·s) was measured and poured into a WARING mixer after the test. After shearing at a speed of 3000 r / min for 5 min, the viscosity after shearing was tested. Finally, the viscosity retention values ​​before and after shearing were calculated, as shown in Table 4.

[0118] Table 4 Viscosity shear retention rate corresponding to sample viscosity of 10mPa·s and 20mPa·s

[0119]

[0120] In summary, the present invention discloses a shear-resistant, high-drag-reducing, high-viscosity, slippery water drag reducer and a preparation method thereof. The drag reducer is prepared by polymerization of acrylamide, sodium acrylate, a sulfonate-containing hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight regulator and a composite initiator. The present invention cooperates with a special sulfonate-containing hydrophobic monomer, a hydrophobic unit microblock regulator matched with the hydrophobic monomer and the control of the polymer molecular weight, and synergistic polymerization is achieved. The several polymer substances work together to synthesize a polymer molecular structure different from that of the prior art. The difference in molecular structure and the excellence of molecular structure can significantly improve the solubility and viscosity-increasing properties of polymers; improve the shear degradation resistance of drag reducers; have excellent sand-carrying and drag-reducing properties; overcome the shortcomings of existing drag reducers such as weak shear resistance, rapid decrease in drag reduction rate, and poor sand-carrying properties, and can meet the special requirements of deep / ultra-deep oil and gas reservoir fracturing for fracturing fluid rheology and "high wellbore drag reduction". This invention provides key material support for the development of deep / ultra-deep oil and gas resources and ensures the goal of efficient development of deep / ultra-deep oil and gas resources.

[0121] At this point, those skilled in the art recognize that, although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the contents disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A shear-resistant, high-drag-reducing, high-viscosity slippery water drag reducer, characterized in that: The drag reducer is formed by hydrolysis after polymerization of acrylamide, sulfonate ion-containing hydrophobic monomer, hydrophobic unit microblock regulator, molecular weight regulator and composite initiator, i.e. post-hydrolysis process; or formed by polymerization of acrylamide, sodium acrylate, sulfonate ion-containing hydrophobic monomer, hydrophobic unit microblock regulator, molecular weight regulator and composite initiator, i.e. copolymerization process; The molecular structure of the drag reducer is: ； Wherein, x, y, z are the number of each repeating unit; In the post-hydrolysis process, the molar ratio of acrylamide to the sulfonate ion-containing hydrophobic monomer is 1: 0.003-0.005; In the copolymerization process, the molar ratio of acrylamide, sodium acrylate, and sulfonate-containing ion-type hydrophobic monomer is 1: 0.2-0.4: 0.003-0.005; The mass ratio of the hydrophobic unit microblock regulator to the sulfonate ion-containing hydrophobic monomer is 4:1-2:1; The mass ratio of molecular weight regulator to reaction system is 0.0075%-0.01%; The mass ratio of the composite initiator to the reaction system is 0.0115%-0.0225%; After the polymerization reaction is completed in the post-hydrolysis process, sodium hydroxide is used for post-hydrolysis, and the molar ratio of acrylamide monomer to sodium hydroxide is 1:0.2-0.4; The structural formula of the sulfonate ion-containing hydrophobic monomer is: ; Wherein, the R group is a C14 alkyl group or a C16 alkyl group; The hydrophobic unit microblock regulator is one or more of AEO-7, AEO-9, OP-8, and OP-10; The molecular weight regulator is one or more of sodium formate, sodium hypophosphite, and n-butyl mercaptan; The composite initiator is a multi-element initiator, which is composed of an inorganic oxidant, an organic oxidant, a reducing agent, and a water-soluble azo initiator. The inorganic oxidant is a persulfate, and the addition amount is 0.002-0.004% of the reaction system; the organic oxidant is an organic hydrogen peroxide, and the addition amount is 0.001-0.003% of the reaction system; the reducing agent is one of sodium sulfite and sodium bisulfite, and the addition amount is 0.0075-0.0125% of the reaction system; the addition amount of the water-soluble azo initiator is 0.001-0.003% of the reaction system.

2. A shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer as claimed in claim 1, characterized in that: The molecular weight of the drag reducer is in the range of 2000-2500 million.

3. A shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer as claimed in claim 1, characterized in that: The inorganic oxidant is ammonium persulfate, sodium persulfate or potassium persulfate; the organic oxidant is one or more of tert-butyl hydroperoxide and cumene hydroperoxide.

4. A shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer as claimed in claim 1, characterized in that: The water-soluble azo initiator is one of 2,2-azo(2-(2-imidazoline-2-yl)propane) dihydrochloride, 2,2-azo(2-methyl-N-(2-hydroxyethyl)acrylamide), and 2,2-azobis(2-methylpropane) hydrochloride.

5. A shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer as claimed in claim 1, characterized in that: The composite initiator is tert-butyl hydroperoxide, ammonium persulfate, sodium bisulfite, and 2,2-azo(2-(2-imidazoline-2-yl)propane) dihydrochloride.

6. A shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer as claimed in claim 1, characterized in that: The preparation method of the sulfonate ion-containing hydrophobic monomer is as follows: Step S1: in a three-necked flask equipped with a magnetic stirrer, a reflux cold flow tube, a thermometer, and two constant pressure dropping funnels, tetradecylamine or hexadecylamine and a catalyst are added in sequence, 2-sodium bromoethylsulfonate or 2-sodium chloroethylsulfonate solution is added to one of the constant pressure dropping funnels, and NaOH solution is added to the other constant pressure dropping funnel; by adjusting the dropping speed of the NaOH solution, the pH value of the reaction is controlled, and the reaction is carried out at a temperature of 50-70° C. for 6-9 hours; after the reaction is completed, a precipitate is precipitated in ethanol, and filtered to obtain an intermediate sodium 2-tetradecylaminoethanesulfonate or sodium 2-hexadecylaminoethanesulfonate; Step S2: dissolving the intermediate obtained in step S1 in dichloromethane, and adding Na2CO3 as an acid binding agent; dropping acryloyl chloride from a constant pressure dropping funnel, controlling the temperature at 15-20°C, reacting for 18-24 hours, removing dichloromethane by reduced pressure distillation, and then recrystallizing with ethanol to obtain the target monomer, which is a sulfonate ion-containing hydrophobic monomer.

7. A shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer as claimed in claim 6, characterized in that: In the step S1, the molar ratio of tetradecylamine or hexadecylamine to sodium 2-bromoethylsulfonate or sodium 2-chloroethylsulfonate is 1:0.8-1:0.9; the catalyst is tetrabutylammonium bromide, and its content is 1% of the mass of tetradecylamine or hexadecylamine; during the reaction, the dropping speed of the NaOH solution is adjusted according to the pH change to control the pH value at 9-12; in the step S2, the molar ratio of the intermediate, Na2CO3, and acryloyl chloride is 1:3:

3.

8. A method for preparing a shear-resistant, high-drag-reducing, high-viscosity slick water drag reducer according to any one of claims 1 to 7, characterized in that: The preparation method uses a post-hydrolysis process or a copolymerization process: Among them, the post-hydrolysis process is detailed as follows: Adding acrylamide monomer and sulfonate ion-containing hydrophobic monomer according to the formula ratio, and using ultrapure water to prepare a mixed solution with a total monomer mass concentration of 20-35%; adding a hydrophobic unit microblock regulator and a molecular weight regulator to the mixed solution, and then adjusting the solution pH to 7.0-9.0, and adding a water-soluble azo initiator and a reducing agent after lowering the system temperature to 0-5°C; introducing nitrogen and stirring for 30-40 minutes, and then adding an oxidant, and adiabatic polymerization for 3-8 hours. After the adiabatic polymerization is completed, granulation, hydrolysis, drying, and crushing are performed to obtain a target polymer; The copolymerization process is detailed as follows: The acrylamide monomer, sodium acrylate and sulfonate ion-containing hydrophobic monomer are added according to the formula ratio, and ultrapure water is used to prepare a mixed solution with a total monomer mass concentration of 20-35%; after adjusting the pH to 7.0 with sodium hydroxide, a hydrophobic unit microblock regulator and a molecular weight regulator are added to the mixed solution, and then the pH value of the solution is adjusted to 7.0-9.0, and a water-soluble azo initiator and a reducing agent are added after the system temperature is reduced to 0-5°C; nitrogen is introduced and stirred for 30-40 minutes, and then an oxidant is added, and adiabatic polymerization is carried out for 3-8 hours. After the adiabatic polymerization is completed, granulation, drying and crushing are carried out to obtain a target polymer.

9. The preparation method as claimed in claim 8, characterized in that The pH value of the solution is adjusted by sodium hydroxide and acetic acid; after the hydrophobic unit microblock regulator is added, the pH value of the solution is 8.0-8.5; the system temperature is 0° C.; and the adiabatic polymerization time is 5-7 hours.

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