Slippery water drag reducer as well as preparation method and application thereof

Abstract

The invention discloses a slickwater drag reducer as well as a preparation method and application thereof, and relates to the technical field of petroleum industry. The slickwater drag reducer disclosed by the invention comprises the following components in parts by weight: 200-350 parts of a solvent, 1-5 parts of a thixotropic agent, 150-200 parts of polyacrylamide and derivatives thereof, and 4-8 parts of a surfactant, the thixotropic agent is silane coupling agent modified magnesium lithium silicate. The silane coupling agent modified magnesium lithium silicate is used as the thixotropic agent, so that better thixotropy can be obtained under the condition that the usage amount of the thixotropic agent is small, the content of water insoluble substances in the slick water drag reducer is reduced, and the damage of the slick water drag reducer to an oil and gas reservoir is reduced.

Description

Technical Field

[0001] This invention relates to the field of petroleum industry technology, and more specifically, to a slickwater drag reducer, its preparation method, and its application. Background Technology

[0002] With the surge in unconventional oil and gas resource development, volumetric fracturing has become an effective measure for the stimulation of tight reservoirs, and slickwater fracturing technology is beneficial for the connection of microfractures. This technology generally involves high flow rates, and the drag-reducing agent in the slickwater fracturing fluid must have good friction-reducing properties to better reduce the construction pressure, thereby meeting the requirements of high-flow-rate operations and reducing the difficulty of construction.

[0003] Slickwater fracturing fluid requires a huge amount of water, but the use of freshwater for reservoir fracturing in western my country is limited. Using such large quantities of water could threaten the freshwater supply to other communities, and the cost of obtaining and transporting water to the well site is very high. To meet the need for freshwater and save costs, various water treatment technologies are used to remove solids and impurities from return water using chemical and mechanical methods for reuse. However, desalination operations are costly and uneconomical.

[0004] Therefore, minimizing freshwater usage, diluting produced water with freshwater in a specific ratio for preparing slickwater fracturing fluid, and reducing wastewater treatment are the only ways to reduce operating costs and improve oil and gas recovery in unconventional formations.

[0005] Currently, the most widely used drag-reducing agents are inverse emulsion polyacrylamide and suspension emulsion polyacrylamide. Inverse emulsion systems offer good drag reduction and salt tolerance ≤40000mg / L, but are only suitable for low to medium salinity water environments. Oil-based suspension emulsion systems have large polymer molecules, excellent drag reduction, and controllable salt tolerance; however, the production process involves adding large amounts of modified bentonite, artificially increasing the water-insoluble content of the fracturing fluid and increasing reservoir damage. Therefore, there is an urgent need for a slickwater drag-reducing agent that possesses good drag reduction properties, salt tolerance, and minimal reservoir damage. Summary of the Invention

[0006] The main objective of this invention is to provide a slickwater drag reducer, its preparation method, and its application, so as to solve the problem that existing slickwater drag reducers cannot simultaneously possess strong salt resistance and minimal damage to reservoirs.

[0007] To solve the above-mentioned technical problems, according to a first aspect of the present invention, a slickwater drag reducing agent is provided, which comprises the following components in parts by weight: 200-350 parts of solvent, 1-5 parts of thixotropic agent, 150-200 parts of polyacrylamide and its derivatives, and 4-8 parts of surfactant; wherein the thixotropic agent is silane coupling agent modified magnesium lithium silicate.

[0008] Furthermore, the preparation method of the above-mentioned silane coupling agent modified lithium magnesium silicate includes:

[0009] Lithium magnesium silicate is added to water, the pH value is adjusted to 4-7, and the mixture is heated to activate it, thus obtaining an activated slurry.

[0010] A cationic silane coupling agent solution was added to the above activated slurry for modification treatment, followed by filtration and drying to obtain the silane coupling agent modified magnesium lithium silicate.

[0011] Furthermore, the above-mentioned heating activation temperature is 30-50℃ and the time is 20-40 min; and / or, the modification treatment temperature is 70-90℃ and the time is 3-6 h.

[0012] Furthermore, the above-mentioned cationic silane coupling agent solution contains a cationic silane coupling agent, an organic alcohol, and water; wherein the mass ratio of the cationic silane coupling agent, the organic alcohol, and water is 10:(15-20):(70-75); the cationic silane coupling agent is C 12 -C 18 Alkyl cationic silane coupling agents.

[0013] Furthermore, in the preparation method of silane coupling agent modified magnesium lithium silicate, the mass ratio of the raw material cationic silane coupling agent to magnesium lithium silicate is (5-25):100.

[0014] Furthermore, C 12 -C 18 The alkyl cationic silane coupling agent is at least one of 3-(triethoxysilyl)propyldimethyldodecylammonium chloride and 3-(triethoxysilyl)propyldimethyloctadecylammonium chloride.

[0015] Further, the solvent is at least one of polyethylene glycol 200, polyethylene glycol 400, and diethyl glycol; the surfactant is at least one of fatty alcohol polyoxyethylene ether and fluorocarbon surfactant; and the polyacrylamide and its derivatives are at least one of polyacrylamide, poly(acrylamide-sodium acrylate-2-acrylamide-2-methylpropanesulfonate), poly(acrylamide-methacryloyloxyethyltrimethylammonium chloride), and poly(acrylamide-sodium acrylate-2-acrylamide-2-methylpropanesulfonate-2-acrylamidooctadecyl sulfonate).

[0016] Furthermore, the aforementioned fatty alcohol polyoxyethylene ether is at least one of AEO-7 and AEO-9; the fluorocarbon surfactant is FS-51; and the weight-average molecular weight of polyacrylamide and its derivatives is 5 million to 10 million.

[0017] According to a second aspect of the present invention, a method for preparing a slippery water drag-reducing agent according to the first aspect of the present invention is provided, comprising the following steps:

[0018] S1, add the solvent to the container according to the ratio, then add the thixotropic agent, and perform the first homogenization to obtain the first mixture;

[0019] S2, the first mixture is mixed with a surfactant and subjected to a second homogenization to obtain a second mixture;

[0020] S3, the second mixture is mixed with polyacrylamide and its derivatives, and then homogenized in the third step to obtain a slippery water drag reducer.

[0021] Furthermore, the conditions for the first, second, and third homogenizations are: 8000-10000 rpm, 1-5 min.

[0022] According to a third aspect of the present invention, the application of the slickwater drag reducer of the first aspect of the present invention or the drag reducer prepared by the preparation method of the second aspect of the present invention in the preparation of slickwater fracturing fluid is provided.

[0023] By applying the technical solution of this invention, and using silane coupling agent-modified magnesium lithium silicate as a thixotropic agent, good thixotropic properties can be obtained with a small dosage, reducing the water-insoluble content in the slickwater drag reducer. Compared with slickwater drag reducers using unmodified magnesium lithium silicate as a thixotropic agent, its damage to the reservoir can be significantly reduced. Furthermore, by limiting the components of the slickwater drag reducer, its salt resistance can be improved, allowing it to be directly formulated with high-salinity produced water from mines to prepare slickwater, reducing freshwater consumption and conserving resources. Attached Figure Description

[0024] Figure 1 The drag reduction rate data is shown in the graph after the slickwater drag reducer in Example 4 is prepared with the reinjection water of Block 1 to form slickwater with a mass fraction of 0.15% of the slickwater drag reducer.

[0025] Figure 2 The graph shows the drag reduction rate data measured after the slickwater drag reducer in Example 4 was prepared with the reinjected water in Block 2 to form slickwater with a mass fraction of 0.15% slickwater drag reducer. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0027] Slickwater fracturing fluid is a liquid used in hydraulic fracturing processes. It is primarily used to apply pressure to rock fractures, thereby breaking the rock and releasing natural gas or crude oil. This fluid is typically composed of water, additives, and auxiliaries, and has low viscosity and surface tension, allowing it to effectively penetrate rock fractures and promote rock fracturing and oil and gas release. Slickwater fracturing fluid plays a crucial role in modern shale gas and tight oil exploration and development.

[0028] Slickwater fracturing fluid requires a large amount of water for preparation. In areas with limited freshwater resources, backflow generated during oil and gas extraction is typically treated to reduce solids and impurities before being used to prepare the slickwater fracturing fluid. Furthermore, drag-reducing agents are usually added to slickwater fracturing fluid to reduce water viscosity, improve its fluidity, and reduce frictional resistance on pipes, containers, and other surfaces. These additives usually contain special surfactants and lubricants that form a thin film in the water, making it more slippery and thus reducing viscosity and flowability. However, drag-reducing agents generally have poor salt resistance. Using conventional backflow to prepare slickwater fracturing fluid requires desalination treatment, which is costly. Currently, drag-reducing agents with higher salt resistance include suspension emulsion-type polyacrylamide drag reducers, but these agents involve the addition of large amounts of modified bentonite during production, increasing the content of water-insoluble substances and causing significant damage to the reservoir. Therefore, they cannot simultaneously address the issues of salt resistance, drag reduction, and reduced reservoir damage.

[0029] To solve the above-mentioned technical problems, in a typical embodiment of the present invention, a slickwater drag reducing agent is provided, which comprises the following components in parts by weight: 200-350 parts of solvent, 1-5 parts of thixotropic agent, 150-200 parts of polyacrylamide and its derivatives, and 4-8 parts of surfactant; the thixotropic agent is silane coupling agent modified magnesium lithium silicate.

[0030] Thixotropic agents in slickwater drag reducers reduce friction and drag by altering the fluid's viscosity and flow characteristics. They modify the fluid's flow properties, making it more fluid and slippery under stress, thus reducing friction and drag and improving flow performance. This invention uses silane coupling agent-modified magnesium lithium silicate as a thixotropic agent, which enhances its thixotropy, thereby reducing the amount of thixotropic agent needed, lowering the content of water-insoluble substances, and improving the long-term stability of the slickwater drag reducer. Adding polyacrylamide and its derivatives improves the drag reducer's salt resistance, enabling rapid dispersion and thickening in high-salt environments, facilitating online application. Adding surfactants reduces the interfacial tension of the slickwater drag reducer, increasing its drag reduction rate. These limitations on the dosage of each component allow them to fully utilize their properties, resulting in a slickwater drag reducer that combines excellent drag reduction, salt resistance, and minimal reservoir damage.

[0031] In a preferred embodiment of the present invention, the method for preparing silane coupling agent modified lithium magnesium silicate includes:

[0032] Lithium magnesium silicate is added to water, the pH value is adjusted to 4-7, and the mixture is heated to activate it, thus obtaining an activated slurry.

[0033] A cationic silane coupling agent solution was added to the above activated slurry for modification treatment, followed by filtration and drying to obtain the silane coupling agent modified magnesium lithium silicate.

[0034] The above method can be used to graft silane coupling agents onto the surface of lithium magnesium silicate, thereby improving the thixotropic properties of the thixotropic agent.

[0035] In a preferred embodiment of the present invention, the temperature for heating activation is 30-50°C and the time is 20-40 min; the temperature for modification treatment is 70-90°C and the time is 3-6 h.

[0036] Under the above conditions, the rate of modification of lithium magnesium silicate by silane coupling agents can be accelerated, thereby improving its preparation efficiency.

[0037] In a preferred embodiment of the present invention, the mass ratio of the raw material cationic silane coupling agent to lithium magnesium silicate is (5-25):100.

[0038] By limiting the mass ratio of silane coupling agent to lithium magnesium silicate, the grafting rate of silane coupling agent can be kept within a moderate range, which helps to further improve the thixotropic properties of the thixotropic agent and improve the stability of the slickwater drag reducer.

[0039] In a preferred embodiment of the present invention, after drying, the silane coupling agent modified magnesium lithium silicate is obtained by grinding to obtain silane coupling agent modified magnesium lithium silicate with fine and uniform particle size.

[0040] Grinding can yield thixotropic agents with better dispersibility, which can play a certain role in improving the drag-reducing properties of slickwater drag-reducing agents.

[0041] In a preferred embodiment of the present invention, the cationic silane coupling agent solution comprises a cationic silane coupling agent, an organic alcohol, and water; wherein the mass ratio of the cationic silane coupling agent, the organic alcohol, and water is 10:(15-20):(70-75); and the cationic silane coupling agent is C 12 -C 18 Alkyl cationic silane coupling agents.

[0042] By limiting the composition of the cationic silane coupling agent solution as described above, the modification process can be made more stable, resulting in a thixotropic agent in which the cationic silane coupling agent is uniformly coated on the surface of lithium magnesium silicate. Limiting the type of cationic silane coupling agent as described above can further improve the thixotropic properties of the thixotropic agent.

[0043] Typical, but not limiting, C 12 -C 18 The alkyl cationic silane coupling agent is at least one of 3-(triethoxysilyl)propyldimethyldodecylammonium chloride and 3-(triethoxysilyl)propyldimethyloctadecylammonium chloride.

[0044] In a preferred embodiment of the present invention, the solvent is a water-soluble solvent. The slippery water fracturing fluid prepared with the drag-reducing agent has excellent water solubility, which can reduce the potential emulsification damage of existing suspension emulsion systems. Optionally, the water-soluble solvent is at least one of organic solvents such as polyethylene glycol 200, polyethylene glycol 400, and diethyl glycol.

[0045] Typically, and not limitingly, polyacrylamide and its derivatives are at least one of polyacrylamide, poly(sodium acrylamide-2-acrylamide-2-methylpropanesulfonate), poly(acrylamide-methacryloyloxyethyltrimethylammonium chloride), and poly(sodium acrylamide-2-acrylamide-2-methylpropanesulfonate-2-acrylamidooctadecylsulfonate).

[0046] The aforementioned polyacrylamide and its derivatives can help disperse particulate matter in water evenly, preventing it from depositing on the surface of pipes or equipment, thereby reducing resistance and improving the flow performance of fluids. They can also form a thin film covering the surface of pipes or equipment, reducing the frictional resistance between the fluid and the solid surface, thereby reducing energy loss and lowering the resistance during fluid transport.

[0047] In a preferred embodiment of the present invention, the surfactant is at least one selected from fatty alcohol polyoxyethylene ether and fluorocarbon surfactant. All of the above surfactants have good properties for reducing interfacial tension.

[0048] Typically, but not limitingly, the fatty alcohol polyoxyethylene ether is at least one of AEO-7 and AEO-9, and the fluorocarbon surfactant is FS-51.

[0049] In a preferred embodiment of the present invention, the weight-average molecular weight of polyacrylamide and its derivatives is 5 million to 10 million. Limiting the molecular weight of polyacrylamide and its derivatives can further improve their salt resistance and reduce their damage to reservoirs.

[0050] In another typical embodiment of the present invention, a method for preparing the slippery water drag-reducing agent of the first aspect of the present invention is provided, comprising the following steps:

[0051] S1, add the solvent to the container according to the ratio, then add the thixotropic agent, and perform the first homogenization to obtain the first mixture;

[0052] S2, the first mixture is mixed with a surfactant and subjected to a second homogenization to obtain a second mixture;

[0053] S3, the second mixture is mixed with polyacrylamide and its derivatives, and then homogenized in the third step to obtain a slippery water drag reducer.

[0054] In a preferred embodiment of the present invention, the conditions for the first homogenization and the second homogenization are: 8000-10000 rpm, 1-5 min.

[0055] Through the above three homogenization processes, a slickwater drag reducer with uniform composition can be obtained, which has high stability and good drag reduction rate.

[0056] In another typical embodiment of the present invention, the application of the slickwater drag reducer of the first aspect of the present invention or the drag reducer prepared by the preparation method of the second aspect of the present invention in the preparation of slickwater fracturing fluid is provided.

[0057] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0058] Polyacrylamide and its derivatives

[0059] Polyacrylamide: weight average molecular weight of 8 million;

[0060] Poly(acrylamide-sodium acrylate-2-acrylamide-2-methylpropanesulfonate): obtained by copolymerization of acrylamide, sodium acrylate and sodium 2-acrylamide-2-methylpropanesulfonate, with a weight-average molecular weight of 8 million;

[0061] Poly(acrylamide-methacryloyloxyethyltrimethylammonium chloride): obtained by copolymerization of methacryloyloxyethyltrimethylammonium chloride and acrylamide, with a weight-average molecular weight of 8 million;

[0062] Poly(acrylamide-sodium acrylate-2-acrylamide-2-methylpropanesulfonic acid-2-acrylamidooctadecyl sulfonate): obtained by copolymerization of acrylamide, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid, and 2-acrylamidooctadecyl sulfonate, with a weight-average molecular weight of 8 million.

[0063] thixotropic agents

[0064] Thixotropic agent 1: Weigh 475g of deionized water and add it to a 1000mL three-necked reaction flask. Turn on the electric stirrer and slowly add 25g of lithium magnesium silicate (Tianmen Hengchang Chemical, HC0221). Turn on the stirrer and adjust the pH value to 4.5 with 0.2mol / L hydrochloric acid. Heat to 40℃ and activate for 30min to obtain an activated slurry. Add 37.5g of cationic silane coupling agent solution (3-(triethoxysilyl)propyldimethyldodecyl ammonium chloride, anhydrous ethanol, and water in a mass ratio of 10:15:75) dropwise to the activated slurry over 30min. Then heat to 80℃ and stir rapidly for 4h. After cooling to room temperature, filter, dry, grind, and pass through a 200-mesh sieve to obtain silane coupling agent modified lithium magnesium silicate.

[0065] Thixotropic agent 2: Weigh 475g of deionized water and add it to a 1000mL three-necked reaction flask. Turn on the electric stirrer and slowly add 25g of lithium magnesium silicate (Tianmen Hengchang Chemical, HC0221). Turn on the stirrer and adjust the pH value to 4.5 with 0.2mol / L hydrochloric acid. Heat to 40℃ and activate for 30min to obtain an activated slurry. Add 25g of cationic silane coupling agent solution (3-(triethoxysilyl)propyldimethyloctadecyl ammonium chloride, anhydrous ethanol, and water in a mass ratio of 10:20:70) dropwise to the activated slurry over 30min. Then heat to 80℃ and stir rapidly for 4h. After cooling to room temperature, filter, dry, grind, and pass through a 200-mesh sieve to obtain silane coupling agent modified lithium magnesium silicate.

[0066] Example 1

[0067] One embodiment of the slippery water drag reducing agent of the present invention is shown in Table 1, and the preparation method is as follows:

[0068] S1, add solvent to beaker, then add thixotropic agent, and use a homogenizer to shear at 9000 rpm for 2 minutes to obtain the first mixture;

[0069] S2, the first mixture is mixed with a surfactant, and the mixture is sheared at 9000 rpm for 1 minute using a homogenizer to obtain the second mixture;

[0070] S3, the second mixture is mixed with polyacrylamide and its derivatives, and sheared at 9000 rpm for 2 minutes using a homogenizer to obtain the slippery water drag reducer.

[0071] Examples 2-5

[0072] The embodiments of the slippery water drag reducing agent of the present invention differ from Embodiment 1 only in that the components of the slippery water drag reducing agent are different, as shown in Table 1.

[0073] Comparative Example 1

[0074] A slickwater drag reducer differs from Example 1 only in that the components of the slickwater drag reducer are different, as shown in Table 1.

[0075] Table 1 (parts by weight)

[0076]

[0077]

[0078] Performance testing

[0079] (1) Viscosity and salt resistance test

[0080] Table 2 shows the water quality analysis results of the reinjected water from Block 1. In a 250mL beaker, 200mL of Block 1 reinjected water was added, and magnetic stirring was started. 0.4mL of slickwater drag reducer was added using a syringe. After magnetic stirring for 5 minutes, slickwater with a slickwater drag reducer volume fraction of 0.2% was obtained. The viscosity was tested using a capillary at 27℃, and the appearance was observed visually. The results are recorded in Table 3. In a 250mL beaker, 200mL of Block 1 reinjected water was added, and magnetic stirring was started. 2mL of slickwater drag reducer was added using a syringe. After magnetic stirring for 5 minutes, slickwater with a slickwater drag reducer volume fraction of 1.0% was obtained. After standing in a 30℃ water bath for 60 minutes, the viscosity was tested using a six-speed viscometer, and the appearance was observed visually. The results are recorded in Table 4. Add 200 mL of block 2 reinjection water to a 250 mL beaker, turn on magnetic stirring, add 3 mL of slickwater drag reducer using a syringe, and after magnetic stirring for 5 min, obtain slickwater with a volume fraction of 1.5% slickwater drag reducer. After standing in a 30℃ water bath for 60 min, test the viscosity with a six-speed viscometer and observe the appearance with the naked eye. The results are recorded in Table 5.

[0081] Table 2 (Unit: mg / L)

[0082] Analysis Project Block 1 water reinjection Block 2 water reinjection <![CDATA[K + +That + ]]> 65921 67924 <![CDATA[Ca 2+ ]]> 741 6064 <![CDATA[Mg 2+ ]]> 360 734 <![CDATA[Cl - ]]> 100251 111464 <![CDATA[SO4 2- ]]> 4591 8136 <![CDATA[OH - ]]> 0 0 <![CDATA[CO3 2- ]]> 0 0 <![CDATA[HCO3 - ]]> 634 235 Total mineralization 172499 194558 pH 7.09 6.067

[0083] Table 3

[0084] project <![CDATA[Viscosity (mm 2 / s)]]> Slippery appearance Example 1 1.65 transparent Example 2 2.08 transparent Example 3 1.59 transparent Example 4 1.52 transparent Example 5 1.52 transparent Comparative Example 1 1.96 translucent

[0085] Table 4

[0086]

[0087]

[0088] Table 5

[0089] project <![CDATA[Viscosity (mm 2 / s)]]> Slippery appearance Example 1 54 transparent Example 2 72 transparent Example 3 51 transparent Example 4 60 transparent Example 5 51 transparent Comparative Example 1 69 cream

[0090] As shown in Tables 3-5, the viscosity of the slippery water prepared with the slippery water drag reducers in the examples and comparative examples is not much different, but the slippery water drag reducers in the examples have higher salt resistance.

[0091] (2) Drag reduction rate test

[0092] Figure 1 The drag reduction rate data is shown in the graph after the slickwater drag reducer in Example 4 is prepared with the reinjection water of Block 1 to form slickwater with a mass fraction of 0.15% of the slickwater drag reducer. Figure 2 This is a graph showing the drag reduction rate measured after the slickwater drag-reducing agent in Example 4 was mixed with the reinjected water from Block 2 to form slickwater with a drag-reducing agent mass fraction of 0.15%. (Source: [Insert Source Here]) Figure 1-2 It can be seen that the drag reduction rate of the slick water prepared with the reinjection water of Block 1 is over 70%, and the drag reduction rate of the slick water prepared with the reinjection water of Block 2 is over 65%, which shows good drag reduction effect and also indicates that it has good salt resistance.

[0093] (3) Surface and interfacial tension test

[0094] Add 200 mL of block 1 reinjection water to a 250 mL beaker, turn on magnetic stirring, add 2 mL of slickwater drag reducer using a syringe, and stir magnetically for 5 min to obtain slickwater with a slickwater drag reducer volume fraction of 1.0%. Add 4 mL of ammonium persulfate solution with a mass fraction of 1%, and let stand in a 90℃ water bath for 120 min to break the gel. Test the residue by vacuum filtration, then test its viscosity at 27℃ using a capillary viscometer, and test its surface and interfacial tension using an A601 fully automatic surface and interfacial tension meter. The results are recorded in Table 6.

[0095] Table 6

[0096]

[0097] As shown in Table 6, the slickwater prepared with the drag-reducing agent in the examples leaves less residue after gel breaking, and has lower surface tension and interfacial tension, indicating that it is less harmful to the reservoir.

[0098] (4) Core damage test

[0099] To evaluate the damage of slickwater to real rock cores, the gelling fluids prepared with the slickwater drag reducer in Example 4 and Comparative Example 1 were tested according to SY / T 5107-2016 "Evaluation Method for Performance of Water-Based Fracturing Fluids". 200 mL of reinjection water from Block 1 was added to a 250 mL beaker, magnetic stirring was started, and 2 mL of slickwater drag reducer was added using a syringe. After magnetic stirring for 5 min, slickwater with a drag reducer volume fraction of 1.0% was obtained. 4 mL of ammonium persulfate solution with a mass fraction of 1% was added, and the mixture was allowed to stand in a 90℃ water bath for 120 min to break the gel. The small rock columns used for testing were taken from the same sandstone core, and the experimental temperature was 90℃. The results are shown in Table 7.

[0100] Table 7

[0101]

[0102] The test results above show that the average core damage rate of the slippery water drag reducer provided by the present invention is only 11.27%, while the average core damage rate of Comparative Example 1 is 25.71%. This result indicates that the slippery water drag reducer described in the present invention causes less damage to the reservoir.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drag-reducing agent for slippery water, characterized in that, The product comprises the following components in parts by weight: 200-350 parts solvent, 1-5 parts thixotropic agent, 150-200 parts polyacrylamide and its derivatives, and 4-8 parts surfactant; wherein the thixotropic agent is silane coupling agent modified magnesium lithium silicate.

2. The slippery water drag reducing agent according to claim 1, characterized in that, The preparation method of the silane coupling agent modified lithium magnesium silicate includes: Lithium magnesium silicate is added to water, the pH value is adjusted to 4-7, and the mixture is heated to activate it, thus obtaining an activated slurry. A cationic silane coupling agent solution was added to the activated slurry for modification treatment, followed by filtration and drying to obtain the silane coupling agent modified magnesium lithium silicate.

3. The slippery water drag reducing agent according to claim 2, characterized in that, The heating activation temperature is 30-50℃ and the time is 20-40 min; and / or The modification treatment is performed at a temperature of 70-90℃ for 3-6 hours; and / or The cationic silane coupling agent solution contains a cationic silane coupling agent, an organic alcohol, and water, wherein the mass ratio of the cationic silane coupling agent, the organic alcohol, and the water is 10:(15-20):(70-75); the cationic silane coupling agent is C 12 -C 18 Alkyl cationic silane coupling agents.

4. The slippery water drag reducing agent according to claim 3, characterized in that, In the preparation method of the silane coupling agent modified magnesium lithium silicate, the mass ratio of the raw material cationic silane coupling agent and magnesium lithium silicate is (5-25):

100.

5. The slippery water drag reducing agent according to claim 3, characterized in that, The C 12 -C 18 The alkyl cationic silane coupling agent is at least one of 3-(triethoxysilyl)propyldimethyldodecylammonium chloride and 3-(triethoxysilyl)propyldimethyloctadecylammonium chloride.

6. The slippery water drag reducing agent according to any one of claims 1 to 5, characterized in that, The solvent is at least one of polyethylene glycol 200, polyethylene glycol 400, and diethyl glycol; the surfactant is at least one of fatty alcohol polyoxyethylene ether and fluorocarbon surfactant; the polyacrylamide and its derivatives are at least one of polyacrylamide, poly(acrylamide-sodium acrylate-2-acrylamide-2-methylpropanesulfonate), poly(acrylamide-methacryloyloxyethyltrimethylammonium chloride), and poly(acrylamide-sodium acrylate-2-acrylamide-2-methylpropanesulfonate-2-acrylamidooctadecyl sulfonate).

7. The slippery water drag reducing agent according to claim 6, characterized in that, The fatty alcohol polyoxyethylene ether is at least one of AEO-7 and AEO-9; the fluorocarbon surfactant is FS-51; and the weight-average molecular weight of the polyacrylamide and its derivatives is 5 million to 10 million.

8. A method for preparing a drag-reducing agent for slippery water according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1, add the solvent to the container according to the ratio, then add the thixotropic agent, and perform the first homogenization to obtain the first mixture; S2, the first mixture is mixed with a surfactant and homogenized to obtain a second mixture; S3, the second mixture is mixed with polyacrylamide and its derivatives, and then homogenized in a third step to obtain the slippery water drag reducer.

9. The method for preparing the slippery water drag-reducing agent according to claim 8, characterized in that, The conditions for the first and second homogenizations are: 8000-10000 rpm, 1-5 min.

10. The use of a slickwater drag reducer according to any one of claims 1 to 7 or a slickwater drag reducer prepared by any one of claims 8 to 9 in the preparation of slickwater fracturing fluid.

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