Salt-tolerant non-plant gum powder drag reducer and preparation method and application thereof

Abstract

The application relates to a salt-resistant non-plant glue powder drag-reducing agent and a preparation method and application thereof. The drag-reducing agent comprises acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl) acrylamide, a functional monomer R and proper amount of water, and the mass fraction ratio of the acrylamide, the 2-acrylamide-2-methylpropanesulfonic acid, the N-(4-hydroxy-3-methoxybenzyl) acrylamide and the functional monomer R is 50-85:10-20:5-10:5-15. The designed drag-reducing agent is composed of the basic structure of polymer molecules by introducing the monomer with a sulfonic acid group and a rigid side group and acrylamide, and the existence of the functional monomer effectively improves the tackiness, temperature resistance and mineralization resistance of the polymer.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemistry and application, specifically relating to a salt-resistant non-plant adhesive powder drag reducer, its preparation method, and its application. Background Technology

[0002] With the development of unconventional oil reservoirs both domestically and internationally, slickwater fracturing fluid technology has been widely applied. As the core of the slickwater system, drag reducers can effectively reduce friction during fracturing operations, achieving the effect of network volumetric fracturing, reducing pump injection pressure, and increasing the fracturing flow rate to create fractures. With the increasing demand for slickwater fracturing fluids, higher requirements are being placed on the performance of drag reducers.

[0003] Currently, drag-reducing agents used in fracturing mainly include bio-polysaccharide-based drag-reducing agents, surfactant-based drag-reducing agents, and polymer-based drag-reducing agents. Bio-polysaccharide-based drag-reducing agents generally have poor drag-reducing performance, long swelling times, and high residue content, and have been gradually replaced by other drag-reducing agents. Surfactant-based drag-reducing agents, due to their high concentration requirements, poor compatibility, and significant environmental impact, have also seen a significant decrease in usage frequency. Polymer-based drag-reducing agents are currently the most widely used drag-reducing agents.

[0004] Polymer drag reducers can be broadly classified into emulsion and solid powder types. Emulsion drag reducers have been widely adopted due to their advantages of rapid dissolution, simple on-site preparation, and no need for pre-preparation. However, existing emulsion systems suffer from low solid content and significant environmental impact, problems that remain unresolved. Furthermore, these drag reducers experience severe molecular chain coiling in high-salinity brine, leading to a substantial decrease in their viscosity-enhancing effect. Therefore, it is necessary to develop a salt-resistant powder drag reducer suitable for high-salinity brine to meet the development needs of unconventional oil and gas reservoirs.

[0005] Publication (Announcement) No.: CN 110452677B modifies MoS2 and prepares it into a suspension. This suspension is then compounded and stirred with a polymer solution to obtain a black drag-reducing emulsion. This improves the drag reduction rate of the product, reduces the required concentration, and enhances the stability of the system, allowing for long-term storage. Publication (Announcement) No.: CN 108192587B provides a multifunctional clean fracturing fluid drag-reducing agent, with monomers consisting of (2... -The target product was obtained by emulsion polymerization of acryloyloxyethoxybenzyltriethylammonium chloride, N-vinylpyrrolidone, glyceryl carbonate, and allyl polyoxyethylene ether. Patent CN110194816B synthesized a salt-resistant drag-reducing agent using a pre-copolymerization hydrolysis process, with an effective content of approximately 25%. Patent CN 107964399B synthesized a drag-reducing agent emulsion integrating drag reduction, sterilization, anti-swelling, and drainage assistance using reverse emulsion polymerization with methacryloyloxyethyltrimethylammonium chloride, 2-phenoxyethyl acrylate, and similar derivatives as monomers, but did not provide specific salt resistance effects. Therefore, most drag-reducing agents currently available are emulsion-type, some possessing drag reduction, anti-swelling, and drainage assistance functions, and exhibiting certain salt resistance. However, when used as linear adhesives or gels, viscosity cannot be guaranteed. Viscosity under high salinity conditions is even less suitable for application requirements.

[0006] Patent CN 113943568 describes a suspension-type drag-reducing agent prepared from salt-resistant and high-temperature-resistant drag-reducing agent powder. This agent has a high effective content (30%–40%) and a large molecular weight, solving the problem of low viscosity under high salinity conditions. The preparation method involves using white oil as the oil phase, adding stabilizers such as organoclay, carboxymethyl cellulose, and emulsifiers, and stirring thoroughly while simultaneously adding the salt-resistant and high-temperature-resistant drag-reducing agent powder. This method is relatively simple and can prepare different types of drag-reducing agent suspensions according to actual needs. However, a problem with this method is that due to the high drag-reducing agent content, long-term storage can easily lead to aggregation, reducing the solid content and thus affecting product performance. Summary of the Invention

[0007] To address the problems of low effective content, short shelf life, and poor salt resistance in existing emulsion-type acrylamide, the present invention aims to: 1) provide a salt-resistant non-plant-based adhesive powder drag-reducing agent; 2) provide a method for preparing the salt-resistant non-plant-based adhesive powder drag-reducing agent; and 3) provide applications of the aforementioned salt-resistant non-plant-based adhesive powder drag-reducing agent. The salt-resistant non-plant-based adhesive powder drag-reducing agent obtained by the present invention significantly improves its salt resistance by introducing sulfonic acid groups and functional monomers. Simultaneously, this drag-reducing agent exhibits rapid dissolution in water, high kinematic viscosity, and excellent drag-reducing performance.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The first objective of this invention is to provide a salt-resistant non-plant adhesive powder drag-reducing agent, the general structural formula of which is shown in Formula I:

[0010] In the formula, m, n, p, and y are the molar ratios of monomers, and m:n:p:y = 1~6:1~5:2~4:2~5;

[0011] R stands for functional monomer.

[0012]

[0013] As a further improvement of the present invention, the functional monomer R is preferably at least one of N,N-docodimethylamine, octadecyl methacrylate, sodium p-styrenesulfonate, and octadecyldimethylpropenylammonium chloride.

[0014] Furthermore, the salt-resistant non-plant adhesive powder drag reducer includes acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R, wherein the mass ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R is (50-85):(10-20):(5-10):(5-15).

[0015] A second objective of this invention is to provide a method for preparing a salt-resistant non-plant adhesive powder drag-reducing agent, the method comprising the following steps:

[0016] S1. Take acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide and functional monomer R according to the ratio, add deionized water, and mix evenly to obtain a mixed solution; wherein, the mass ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide and functional monomer R is (50~85):(10~20):(5~10):(5~15);

[0017] S2. Adjust the pH of the mixed solution to 7 with a pH adjuster, add the initiator, and continue heating and stirring. After reacting for 5-8 hours, transfer the obtained product to a large container and wash the product with ethanol to obtain the copolymer.

[0018] S3. Cut, dry, and pulverize the obtained copolymer to obtain the target product.

[0019] Furthermore, in S1, the reaction temperature is preferably controlled at 50-70°C, and the reaction time is preferably controlled at 6-7 hours; in S2, the heating temperature is preferably 50-80°C.

[0020] Furthermore, the pH adjuster is one of sodium hydroxide, calcium hydroxide, ammonia, and ethylenediamine.

[0021] Furthermore, the initiator is one of 2,2-azobis(N-butyl-2-methylpropionamide), azobisisobutylamidine hydrochloride, ammonium persulfate, and potassium persulfate.

[0022] A third objective of this invention is to provide an application of a salt-resistant non-plant-based adhesive powder drag reducer in slickwater fracturing fluids.

[0023] The slickwater fracturing fluid is composed of the following raw materials:

[0024]

[0025] Furthermore, the viscosity modifier is one or a mixture of sodium dodecylbenzenesulfonate and sodium oleate.

[0026] Furthermore, the anti-swelling agent is one or more of aluminum trichloride, ammonium chloride, and dodecyltrimethylammonium chloride.

[0027] Furthermore, the discharge aid is one or more of sodium perfluorononenoxybenzenesulfonate, polyoxyethylene alkylphenol ether sulfate, and alkyltrimethylammonium bromide.

[0028] Furthermore, the preparation method of the slickwater fracturing fluid includes the following steps: adding water for mixing according to the formula composition in a mixing container, starting the pump for circulation, and under the condition of pump circulation, adding salt-resistant non-plant glue powder drag reducer, anti-swelling agent, and drainage aid in sequence according to the formula ratio, continuing to increase the drainage rate to 5L / min-20L / min, continuously stirring until the drag reducer is fully dissolved, and finally adding viscosity modifier, circulating for 5-10 minutes to obtain slickwater fracturing fluid;

[0029] The salt-resistant non-plant adhesive powder drag reducer contains 0.1% to 2% by weight, the viscosity modifier contains 0% to 2% by weight, the anti-swelling agent contains 0.5% to 1.5% by weight, the drainage aid contains 0.2% to 1% by weight, and the water contains 94.3% to 98.4% by weight.

[0030] By adopting the above technical solution, the present invention has the following beneficial effects:

[0031] 1. The salt-resistant non-plant adhesive powder drag reducer prepared by the present invention introduces monomers with sulfonic acid groups and rigid side groups to form the basic structure of polymer molecules with acrylamide, while the presence of functional monomers effectively improves the polymer's tackification, temperature resistance and mineralization resistance.

[0032] 2. The preparation method of the salt-resistant non-plant adhesive powder drag reducer described in this invention can prepare a salt-resistant non-plant adhesive powder drag reducer that is temperature-resistant, salt-resistant, and has excellent solubility. The technology is simple and reliable, with high yield, and is suitable for large-scale industrial production.

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0034] The invention can be further understood in conjunction with the following detailed description of preferred embodiments and included examples. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. If any definition of a specific term disclosed in the prior art differs from any definition provided herein, the definition provided herein shall prevail.

[0035] It should be noted that the implementation conditions used in the examples can be further adjusted according to the specific experimental environment, and the implementation conditions not specified are usually those in conventional experiments. Unless otherwise specified, the preparation methods mentioned in this invention are all conventional methods; unless otherwise specified, all chemical reagents and chemicals mentioned in the following examples are commercially available.

[0036] In one typical embodiment of this application, a salt-resistant non-plant adhesive powder drag-reducing agent is provided, the general structural formula of which is shown in Formula I:

[0037]

[0038] In the formula, m, n, p, and y are the molar ratios of monomers, and m:n:p:y = 1~6:1~5:2~4:2~5;

[0039] R stands for functional monomer.

[0040] As a further improvement to the above-mentioned technical solution of the present invention, the functional monomer R is preferably at least one of N,N-docodimethylamine, octadecyl methacrylate, sodium p-styrenesulfonate, and octadecyldimethylpropenylammonium chloride.

[0041] As a further optimization of the present invention, the molar ratio of m, n, p, y is preferably m:n:p:y = 1:1:1:1.

[0042] This invention further provides a method for preparing a salt-resistant non-plant adhesive powder drag-reducing agent:

[0043] The synthetic route for this drag-reducing agent is as follows:

[0044]

[0045] The preparation method of the salt-resistant non-plant adhesive powder drag-reducing agent includes the following steps:

[0046] SS1. Take acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide and functional monomer R according to the ratio, add deionized water, and mix well to obtain a mixed solution;

[0047] The mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R is (50-85):(10-20):(5-10):(5-15);

[0048] S2. Adjust the pH of the mixed solution to 7 with a pH adjuster, add the initiator, continue heating and stirring, and after reacting for 5-8 hours, transfer it to a large container and wash the product with ethanol;

[0049] S3. Cut, dry, and pulverize the obtained copolymer to obtain the target product.

[0050] In the above technical solution, the presence of benzene rings in acrylamide and rigid monomers gives the synthesized polymer molecules good temperature resistance, while sulfonic acid groups effectively improve the salt resistance of the polymer molecules.

[0051] Furthermore, in S1, the reaction temperature is preferably controlled at 50-70°C, and the reaction time is preferably controlled at 6-7 hours; in S2, the heating temperature is preferably 50-80°C.

[0052] Furthermore, in S2, the pH adjuster is preferably one of sodium hydroxide, calcium hydroxide, ammonia, and ethylenediamine.

[0053] Further, in S2, the initiator is preferably one of 2,2-azobis(N-butyl-2-methylpropionamide), azobisisobutylamidine hydrochloride, ammonium persulfate, and potassium persulfate.

[0054] The method for preparing salt-resistant non-plant adhesive powder drag reducer described in this invention can prepare a high-efficiency powder-type non-plant adhesive drag reducer that is temperature-resistant, salt-resistant, and has excellent solubility. The technology is simple and reliable, with high yield, and is suitable for large-scale industrial production.

[0055] In yet another typical embodiment of this application, the present invention provides an application of a salt-resistant non-plant adhesive powder drag reducer in slickwater fracturing fluid.

[0056] The slickwater fracturing fluid is composed of the following raw materials:

[0057]

[0058] Furthermore, the salt-resistant non-plant adhesive powder drag reducer includes acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R, wherein the mass ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R is (50-85):(10-20):(5-10):(5-15).

[0059] Furthermore, the viscosity modifier is preferably one or a mixture of sodium dodecylbenzenesulfonate and sodium oleate.

[0060] Furthermore, the anti-swelling agent is preferably one or a mixture of aluminum trichloride, ammonium chloride, and dodecyltrimethylammonium chloride.

[0061] Furthermore, the drainage aid is preferably one or a mixture of sodium perfluorononenoxybenzenesulfonate, polyoxyethylene alkylphenol ether sulfate, and alkyltrimethylammonium bromide.

[0062] The present invention further provides a method for preparing the above-mentioned slickwater fracturing fluid, comprising the following steps: adding water for preparation to a mixing container according to the formula composition, starting a pump for circulation, and under the condition of pump circulation, adding salt-resistant non-plant adhesive powder drag reducer, anti-swelling agent, and drainage aid in sequence according to the formula ratio, continuing to increase the drainage rate to 5L / min-20L / min, continuously stirring until the drag reducer is fully dissolved, and finally adding a viscosity modifier, circulating for 5-10 minutes to obtain the slickwater fracturing fluid;

[0063] The salt-resistant non-plant adhesive powder drag reducer contains 0.1% to 2% by weight, the viscosity modifier contains 0% to 2% by weight, the anti-swelling agent contains 0.5% to 1.5% by weight, the drainage aid contains 0.2% to 1% by weight, and the water contains 94.3% to 98.4% by weight.

[0064] The present invention will be further described below with reference to specific embodiments:

[0065] Example 1 (Synthesis of drag reducer A)

[0066] This embodiment prepares a salt-resistant non-plant adhesive powder drag reducer, the formulation of which is as follows (by weight): 60 parts acrylamide, 10 parts 2-acrylamido-2-methylpropanesulfonic acid, 5 parts N-(4-hydroxy-3-methoxybenzyl)acrylamide, 5 parts N,N-docosahexadecylmethylamine, 3 parts 2,2-azobis(N-butyl-2-methylpropionamide) and 150 parts deionized water.

[0067] The method for preparing the drag-reducing agent includes the following steps:

[0068] S1: Take 60 parts of acrylamide, 10 parts of 2-acrylamide-2-methylpropanesulfonic acid, 5 parts of N-(4-hydroxy-3-methoxybenzyl)acrylamide, 5 parts of N,N-docodimethylamine, add 150 parts of deionized water, and mix well to obtain a mixed solution.

[0069] S2: Adjust the pH of the mixed solution to 7 with NaOH solution, add 3 parts of 2,2-azobis(N-butyl-2-methylpropionamide), heat and stir continuously, keep the temperature at 60℃, and after reacting for 6 hours, transfer the obtained product to a large container and wash the product with ethanol;

[0070] S3: The obtained copolymer product is cut, dried, and pulverized to obtain drag-reducing agent A.

[0071] Example 2 (Synthesis of drag reducer B)

[0072] This embodiment prepares a salt-resistant non-plant adhesive powder drag reducer, the formulation of which is as follows by mass parts: 65 parts acrylamide, 15 parts 2-acrylamido-2-methylpropanesulfonic acid, 5 parts N-(4-hydroxy-3-methoxybenzyl)acrylamide, 10 parts N,N-docosahexadecylmethylamine, 4 parts ammonium persulfate and 170 parts deionized water.

[0073] The method for preparing the drag-reducing agent includes the following steps:

[0074] S1: Take 65 parts of acrylamide, 15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 5 parts of N-(4-hydroxy-3-methoxybenzyl)acrylamide, 10 parts of N,N-docosahexadecylmethylamine, add 170 parts of deionized water, and mix well to obtain a mixed solution.

[0075] S2: Adjust the pH of the mixed solution to 7 with NaOH solution, add 4 parts of ammonium persulfate, heat and stir continuously, keep the temperature at 60℃, and after reacting for 6 hours, transfer the obtained product to a large container and wash the product with ethanol.

[0076] S3: The obtained copolymer product is cut, dried, and pulverized to obtain drag-reducing agent B.

[0077] Example 3 (Synthesis of drag reducer C)

[0078] This embodiment prepares a salt-resistant non-plant adhesive powder drag reducer, the formulation of which is as follows (by weight): 70 parts acrylamide, 20 parts 2-acrylamido-2-methylpropanesulfonic acid, 10 parts N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts N,N-docosahexadecylmethylamine, 5 parts azobisisobutylamidine hydrochloride, and 200 parts deionized water.

[0079] The method for preparing the drag-reducing agent includes the following steps:

[0080] S1: Take 70 parts of acrylamide, 20 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10 parts of N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts of N,N-docosahexamethylamine, add 200 parts of deionized water, and mix well to obtain a mixed solution;

[0081] S2: Adjust the pH of the mixed solution to 7 with NaOH solution, add 5 parts of azobisisobutylamidine hydrochloride, heat and stir continuously, keep the temperature at 60℃, react for 6.5h, transfer the obtained product to a large container, and wash the product with ethanol;

[0082] S3: The obtained copolymer product is cut, dried, and pulverized to obtain drag-reducing agent C.

[0083] Example 4 (Synthesis of drag reducer D)

[0084] This embodiment prepares a salt-resistant non-plant adhesive powder drag reducer, the formulation of which is as follows (by weight): 70 parts acrylamide, 20 parts 2-acrylamido-2-methylpropanesulfonic acid, 10 parts N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts octadecyl methacrylate, 5 parts 2,2-azobis(N-butyl-2-methylpropionamide), and 200 parts deionized water.

[0085] The method for preparing the drag-reducing agent includes the following steps:

[0086] S1: Take 70 parts of acrylamide, 20 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10 parts of N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts of octadecyl methacrylate, add 200 parts of deionized water, and mix well to obtain a mixed solution;

[0087] S2: Adjust the pH of the mixed solution to 7 with NaOH solution, add 5 parts of 2,2-azobis(N-butyl-2-methylpropionamide), heat and stir continuously, keep the temperature at 55℃, react for 7 hours, transfer the obtained product to a large container, and wash the product with ethanol;

[0088] S3: The obtained copolymer product is cut, dried, and pulverized to obtain drag-reducing agent D.

[0089] Example 5 (Synthesis of drag reducer E)

[0090] This embodiment prepares a salt-resistant non-plant adhesive powder drag reducer, the formulation of which is as follows (by weight): 70 parts acrylamide, 20 parts 2-acrylamido-2-methylpropanesulfonic acid, 10 parts N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts sodium p-styrenesulfonate, 5 parts 2,2-azobis(N-butyl-2-methylpropionamide) and 200 parts deionized water.

[0091] The method for preparing the drag-reducing agent includes the following steps:

[0092] S1: Take 70 parts of acrylamide, 20 parts of 2-acrylamide-2-methylpropanesulfonic acid, 10 parts of N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts of sodium p-styrenesulfonate, add 200 parts of deionized water, and mix well to obtain a mixed solution;

[0093] S2: Adjust the pH of the mixed solution to 7 with NaOH solution, add 5 parts of 2,2-azobis(N-butyl-2-methylpropionamide), heat and stir continuously, keep the temperature at 55℃, react for 7 hours, transfer the obtained product to a large container, and wash the product with ethanol;

[0094] S3: The obtained copolymer product is cut, dried, and pulverized to obtain drag-reducing agent E.

[0095] Example 6 (Synthesis of drag reducer F)

[0096] This embodiment prepares a salt-resistant non-plant adhesive powder drag reducer, the formulation of which is as follows (by weight): 70 parts acrylamide, 20 parts 2-acrylamido-2-methylpropanesulfonic acid, 10 parts N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts octadecyldimethylpropenylammonium chloride, 5 parts 2,2-azobis(N-butyl-2-methylpropionamide) and 200 parts deionized water.

[0097] The method for preparing the drag-reducing agent includes the following steps:

[0098] S1: Take 70 parts of acrylamide, 20 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10 parts of N-(4-hydroxy-3-methoxybenzyl)acrylamide, 15 parts of octadecyldimethylpropenylammonium chloride, add 200 parts of deionized water, and mix well to obtain a mixed solution;

[0099] S2: Adjust the pH of the mixed solution to 7 with NaOH solution, add 5 parts of 2,2-azobis(N-butyl-2-methylpropionamide), heat and stir continuously, keep the temperature at 55℃, react for 7 hours, transfer the obtained product to a large container, and wash the product with ethanol;

[0100] S3: The obtained copolymer product is cut, dried, and pulverized to obtain drag-reducing agent F.

[0101] Comparative Examples 1-3 (Synthesis of drag-reducing agents a-c)

[0102] This comparative example prepares a salt-resistant non-plant adhesive powder drag-reducing agent.

[0103] The difference from Example 1 is that, in this comparative example, the amount of acrylamide added was replaced with 50 parts (Comparative Example 1), 80 parts (Comparative Example 2), and 85 parts (Comparative Example 3), respectively, to obtain the corresponding products drag reducer a (Comparative Example 1), drag reducer b (Comparative Example 2), and drag reducer c (Comparative Example 3).

[0104] Comparative Examples 4-6 (Synthesis of drag-reducing agents d-f)

[0105] This comparative example prepares a salt-resistant non-plant adhesive powder drag-reducing agent.

[0106] The difference from Example 3 is that, in this comparative example, the polymerization reaction temperature in the preparation method was adjusted to 50℃ (Comparative Example 4), 65℃ (Comparative Example 5), and 70℃ (Comparative Example 6), resulting in the corresponding drag-reducing agents d (Comparative Example 4), e (Comparative Example 5), and f (Comparative Example 6).

[0107] Comparative Examples 7-8 (Synthesis of drag-reducing agents g and h)

[0108] This comparative example prepares a salt-resistant non-plant adhesive powder drag-reducing agent.

[0109] The difference from Example 3 is that the reaction time in the preparation method of this comparative example was adjusted to 5h (Comparative Example 7) and 8h (Comparative Example 8), and the corresponding products drag reducer g (Comparative Example 7) and drag reducer h (Comparative Example 8) were obtained.

[0110] Performance testing

[0111] The base liquid viscosity of the products prepared in Examples 1-6 and Comparative Examples 1-8 was tested. 0.3% drag-reducing agent solutions were prepared using tap water and standard saline solution, respectively. After the drag-reducing agent was completely dissolved, the solution viscosity was tested to evaluate its thickening and salt resistance properties. The test results are shown in Table 1 below.

[0112] Table 1

[0113]

[0114] The experimental results are shown in Table 1. As can be seen from the table, the salt-resistant non-plant adhesive powder drag-reducing agent prepared in this invention exhibits a significant improvement in salt resistance compared to ordinary acrylamide drag-reducing agents. Under standard saline solution conditions, the viscosity retention rate of the drag-reducing agents prepared in this invention is greater than 45%, which is far higher than that of unmodified ordinary acrylamide. Among them, drag-reducing agent F exhibits the best salt resistance, demonstrating that the introduction of the functional monomers 2-acrylamido-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and octadecyldimethylpropenylammonium chloride effectively improves the salt resistance of the drag-reducing agent.

[0115] Application examples

[0116] The drag-reducing agents C to F prepared in Examples 3 to 6 above were used to formulate slickwater fracturing fluid.

[0117] The slickwater fracturing fluid formulation, by percentage, consists of: 0.3 wt% salt-resistant non-plant-based adhesive powder drag reducer, 1% sodium dodecylbenzene sulfonate, 1% ammonium chloride, 0.5% polyoxyethylene alkylphenol ether sulfate salt, with the balance being water.

[0118] The preparation method of the slickwater fracturing fluid is as follows: Add water to the mixing container according to the formula composition, start the pump for circulation, and under the condition of pump circulation, add salt-resistant non-plant glue powder drag reducer, anti-swelling agent and drainage aid in sequence according to the formula ratio, continue to increase the drainage rate, and continue to stir to ensure that the drag reducer is fully dissolved. Finally, add viscosity modifier and circulate for 5-10 minutes to obtain slickwater fracturing fluid.

[0119] The drag reduction performance of the obtained slickwater fracturing fluid was tested, and the test results are shown in Table 2 below:

[0120] Table 2

[0121]

[0122] The results above show that the drag-reducing agent disclosed in this application can still maintain a high apparent viscosity when high-mineralization standard brine is used as the solution preparation water, which demonstrates the excellent salt resistance of the drag-reducing agent. The drag reduction performance test results also show that the drag-reducing agent obtained in this application has excellent drag reduction performance and can meet the needs of on-site construction.

[0123] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A salt-resistant non-plant adhesive powder drag-reducing agent, characterized in that, The general structural formula of the drag-reducing agent is shown in Formula I: In the formula, m, n, p, and y are the molar ratios of monomers, and m:n:p:y = 1~6:1~5:2~4:2~5; R stands for functional monomer.

2. The salt-resistant non-plant adhesive powder drag-reducing agent as described in claim 1, characterized in that: The functional monomer R is at least one of N,N-docodimethylamine, octadecyl methacrylate, sodium p-styrene sulfonate, and octadecyldimethylpropenyl ammonium chloride.

3. The salt-resistant non-plant adhesive powder drag-reducing agent as described in claim 1, characterized in that: The drag reducer comprises acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R, wherein the mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R is (50-85):(10-20):(5-10):(5-15).

4. A method for preparing a salt-resistant non-plant adhesive powder drag-reducing agent according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Take acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide and functional monomer R according to the ratio, add deionized water, and mix evenly to obtain a mixed solution; The mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-(4-hydroxy-3-methoxybenzyl)acrylamide, and functional monomer R is (50-85):(10-20):(5-10):(5-15); S2. Adjust the pH of the mixed solution to 7 with a pH adjuster, add the initiator, continue heating and stirring, and after reacting for 5-8 hours, transfer the obtained product to a large container and wash the product with ethanol; S3. Cut, dry, and pulverize the copolymer obtained in S2 to obtain the target product.

5. The preparation method of the salt-resistant non-plant adhesive powder drag-reducing agent as described in claim 4, characterized in that: The pH adjuster is one of sodium hydroxide, calcium hydroxide, ammonia, and ethylenediamine; The initiator is one of 2,2-azobis(N-butyl-2-methylpropionamide), azobisisobutylamidine hydrochloride, ammonium persulfate, and potassium persulfate.

6. The preparation method of the salt-resistant non-plant adhesive powder drag-reducing agent as described in claim 4, characterized in that: In S1, the reaction temperature is controlled at 50–70℃ and the reaction time is controlled at 6–7h; In S2, the heating temperature is 50-80°C.

7. The application of a salt-resistant non-plant adhesive powder drag-reducing agent, characterized in that: The application of the salt-resistant non-plant adhesive powder drag reducer as described in any one of claims 1-3, or the salt-resistant non-plant adhesive powder drag reducer prepared by the preparation method described in any one of claims 5-7, in slickwater fracturing fluids.

8. The application of the salt-resistant non-plant adhesive powder drag-reducing agent as described in claim 7, characterized in that, The slickwater fracturing fluid is composed of the following raw materials: The remainder is water.

9. The application of the salt-resistant non-plant adhesive powder drag-reducing agent as described in claim 8, characterized in that, The viscosity modifier is one or a mixture of any of sodium dodecylbenzenesulfonate and sodium oleate; The anti-swelling agent is one or a mixture of any of aluminum trichloride, ammonium chloride, and dodecyltrimethylammonium chloride; The drainage aid is one or a mixture of any of the following: sodium perfluorononenoxybenzenesulfonate, polyoxyethylene alkylphenol ether sulfate, and alkyltrimethylammonium bromide.

10. The application of the salt-resistant non-plant adhesive powder drag-reducing agent as described in claim 8, characterized in that, The preparation method of the slickwater fracturing fluid includes the following steps: adding water for mixing according to the formula composition in a mixing container, starting the pump for circulation, and adding salt-resistant non-plant glue powder drag reducer, anti-swelling agent, and drainage aid in sequence according to the formula ratio under the condition of pump circulation, continuing to increase the drainage rate to 5L / min-20L / min, continuously stirring until the drag reducer is fully dissolved, and finally adding viscosity modifier, circulating for 5-10 minutes to obtain slickwater fracturing fluid; The salt-resistant non-plant adhesive powder drag reducer contains 0.1% to 2% by weight, the viscosity modifier contains 0% to 2% by weight, the anti-swelling agent contains 0.5% to 1.5% by weight, the drainage aid contains 0.2% to 1% by weight, and the water contains 94.3% to 98.4% by weight.

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