Aqueous suspending fracturing fluid and method of making same

Abstract

The present application relates to the technical field of water-based fracturing fluid, and is a kind of water phase suspension fracturing fluid and its preparation method, the water phase suspension fracturing fluid is prepared by using modified polyacrylamide as raw material, and then compounding cleanup agent, xanthan gum, suspending agent, organic matter and high mineralization water, which has high viscosity under high salinity.At the same time, the broken glue solution is obtained by adding the broken glue agent to the water phase suspension fracturing fluid, the broken glue time of the broken glue solution is less than 3h, the apparent viscosity of the broken glue solution is less than 5mPa·s, the surface tension of the broken glue solution is less than 28mN / m, and the interfacial tension between the broken glue solution and kerosene is less than 2mN / m, which all meet the requirements of industry standards, greatly improving the fracturing construction progress and effect.

Description

Technical Field

[0001] This invention relates to the field of water-based fracturing fluid technology, specifically an aqueous suspension fracturing fluid and its preparation method. Background Technology

[0002] Fracturing fluids play a crucial role in shaping the fractures produced in the formation and controlling the proppant carrying efficiency. Therefore, the correct selection of fracturing fluid is essential during fracturing operations. There are many types of fracturing fluids, which can generally be classified into oil-based fracturing fluids, water-based fracturing fluids, and foam fracturing fluids based on their physicochemical properties. Water-based fracturing fluids have proven to be the best method for improving oilfield recovery among various fracturing techniques. Using polymers to reduce friction and increase fluid viscosity can improve the fluid's suspending power and proppant transport performance.

[0003] Water-based fracturing fluids can be categorized into natural plant gum fracturing fluids, cellulose fracturing fluids, and synthetic polymer fracturing fluids. However, natural plant gum fracturing fluids have a high residue content, which can easily cause blockage of supported fractures after the gum breaks down, and their temperature resistance is not ideal. Cellulose fracturing fluids are mainly characterized by high friction and poor temperature resistance. Synthetic polymer fracturing fluids have become the inevitable choice for developing salt-tolerant fracturing fluid systems; however, existing polyacrylamide fracturing fluids suffer from poor salt resistance and, under high salinity conditions, are prone to precipitation with high-valence cations, leading to phase separation and a decrease in solution viscosity. Summary of the Invention

[0004] This invention provides an aqueous suspension fracturing fluid and its preparation method, which overcomes the shortcomings of the prior art and can effectively solve the problem of low viscosity of existing polyacrylamide fracturing fluids under high mineralization.

[0005] One of the technical solutions of the present invention is achieved by the following measures: an aqueous suspension fracturing fluid, wherein the raw materials include, by weight percentage, 0.3% to 1.5% modified ammonium polyacrylate, 1% to 5% drainage aid, 5% to 10% xanthan gum, 3% to 6% suspending agent, 1% to 20% organic matter and the balance being mineralized water.

[0006] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: The modified polyacrylamide described above has the following structural formula: Wherein, R1 is an alkane group with 1 to 10 carbon atoms and containing F; R2 is an alkane group with 1 to 5 carbon atoms; R3 is a straight-chain alkane group with 1 to 18 carbon atoms; X is a halogen; a, b, c, and d are the molar percentages of the monomers, where a is 80% to 97%, b is 1% to 10%, c is 1% to 5%, and d is 1% to 5%.

[0007] The modified polyacrylamide described above comprises, by weight, 15 to 25 parts acrylamide, 3 to 5 parts sodium perfluorononenoxybenzenesulfonate, 3 to 5 parts ester organic compounds, 1 to 3 parts (2-acrylamido)ethylundecyldimethylammonium bromide, 0.5 to 1.0 parts initiator, and 65 to 75 parts water.

[0008] The above-mentioned (2-acrylamido)ethylundecyldimethylammonium bromide comprises, by weight, 15 to 25 parts of ethanol, 4 to 6 parts of N,N-dimethylacrylethylenediamine, 9 to 10 parts of undecyl bromide, and 0.4 to 0.6 parts of sodium hydroxide, wherein N,N-dimethylacrylethylenediamine is obtained by reacting N,N-dimethylethylenediamine, carbon tetrachloride, sodium carbonate, and acrylyl chloride.

[0009] The aforementioned ester organic compounds are one of perfluorooctyl ethyl acrylate, dodecylfluoroheptyl acrylate, and 1H,1H,7H-dodecylfluoroheptyl acrylate.

[0010] The initiator mentioned above is a mixture of sodium bisulfite and potassium persulfate in a mass ratio of 1: (5 to 6).

[0011] The modified polyacrylamide described above was obtained by the following method: Preparation of S1,N,N-dimethylacrylamide: S11, after mixing 4 to 6 parts of N,N-dimethylethylenediamine, 10 to 20 parts of carbon tetrachloride and 0.4 to 0.6 parts of sodium carbonate, a mixture is obtained; S12, dissolve 6 to 7 parts of acryloyl chloride in 10 to 20 parts of carbon tetrachloride to obtain a carbon tetrachloride solution containing acryloyl chloride; S13, after adding a carbon tetrachloride solution containing acryloyl chloride to the mixture and mixing and reacting, reaction product a is obtained. After filtering and washing, N,N-dimethylacryloylethylenediamine is obtained. Preparation of S2, (2-acrylamido)ethylundecyldimethylammonium bromide: S21, after mixing the required amounts of ethanol, N,N-dimethylacrylamide, undecane bromide and sodium hydroxide and reacting, reaction product b is obtained; S22, reaction product b was successively cooled, precipitated with diethyl ether, washed, dried and recrystallized with ethyl acetate to obtain (2-acrylamido)ethylundecyldimethylammonium bromide; S3, Preparation of modified polyacrylamide: S31. Add the required amount of acrylamide, sodium perfluorononenoxybenzenesulfonate, ester organic matter, and (2-acrylamido)ethylundecyldimethylammonium bromide to the required amount of water and stir until completely dissolved to obtain a mixed solution. Adjust the pH value of the mixed solution. S32, under a nitrogen atmosphere, the required amount of initiator is added to the mixed solution and a polymerization reaction is carried out to obtain reaction product c. After drying, crushing, washing and drying again, reaction product c is obtained as modified polyacrylamide.

[0012] In step S13 above, the reaction temperature is 0℃ to 5℃ and the reaction time is 2.0h to 2.5h.

[0013] In step S22 above, the reaction temperature is 50°C to 55°C and the reaction time is 70h to 75h.

[0014] In step S32 above, the reaction temperature is 40°C to 50°C and the reaction time is 12h to 14h.

[0015] The aforementioned drainage aid is one or more of sodium perfluorononenoxybenzenesulfonate, hexafluoropropylene oxide trimer, perfluorohexylethanol polyoxyethylene ether, and perfluorononenyl trifluoroethyl ether.

[0016] The aforementioned suspending agent is one or more of nano-silica, nano-titanium dioxide, nano-alumina, and nano-calcium carbonate.

[0017] The aforementioned organic compound is one or more of polydimethylammonium chloride, ethylene glycol monomethyl ether, polyethylene glycol 200, polyethylene glycol 400, and polyethylene glycol 600.

[0018] The above-mentioned mineralized water is a salt water containing sodium ions, calcium ions and chloride ions.

[0019] The above-mentioned aqueous suspension fracturing fluid is obtained by the following method: adding the required amount of modified polyacrylamide, drainage aid, xanthan gum, suspending agent and organic matter to the required amount of mineralized water, stirring evenly and letting it stand to obtain the aqueous suspension fracturing fluid. During stirring, the stirring temperature is 30℃ to 35℃ and the stirring time is 30 min to 35 min. During standing, the standing temperature is 30℃ to 35℃ and the standing time is 4.0 h to 4.5 h.

[0020] The second technical solution of the present invention is achieved through the following measures: a method for preparing an aqueous suspension fracturing fluid, which is carried out as follows: adding a required amount of modified polyacrylamide, drainage aid, xanthan gum, suspending agent and organic matter to a required amount of mineralized water, stirring evenly and then letting it stand to obtain an aqueous suspension fracturing fluid, wherein, during stirring, the stirring temperature is 30°C to 35°C and the stirring time is 30 min to 35 min, and during standing, the standing temperature is 30°C to 35°C and the standing time is 4.0 h to 4.5 h.

[0021] This invention utilizes modified polyacrylamide as a raw material, combined with flow aids, xanthan gum, suspending agents, organic matter, and highly salinized water to prepare an aqueous suspension fracturing fluid, which exhibits high viscosity under high salinity. Furthermore, the fracturing fluid obtained by adding a breaker to the aqueous suspension exhibits a breaker time of less than 3 hours, an apparent viscosity below 5 mPa·s, a surface tension below 28 mN / m, and an interfacial tension between the breaker and kerosene below 2 mN / m, all meeting industry standards and significantly improving the fracturing operation progress and effectiveness. Detailed Implementation

[0022] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0023] The present invention will be further described below with reference to embodiments: Example 1: The aqueous suspension fracturing fluid contains, by weight percentage, 0.3% to 1.5% modified ammonium polyacrylate, 1% to 5% drainage aid, 5% to 10% xanthan gum, 3% to 6% suspending agent, 1% to 20% organic matter, and the balance being mineralized water.

[0024] Example 2: As an optimization of the above examples, a modified polyacrylamide is provided, with the following structural formula: Wherein, R1 is an alkane group with 1 to 10 carbon atoms and containing F; R2 is an alkane group with 1 to 5 carbon atoms; R3 is a straight-chain alkane group with 1 to 18 carbon atoms; X is a halogen; a, b, c, and d are the molar percentages of the monomers, where a is 80% to 97%, b is 1% to 10%, c is 1% to 5%, and d is 1% to 5%.

[0025] In Example 2 of this invention, 10 typical structural formulas of modified polyacrylamide are shown below: Example 3: As an optimization of the above examples, the modified polyacrylamide comprises, by weight, 15 to 25 parts acrylamide, 3 to 5 parts sodium perfluorononenoxybenzenesulfonate, 3 to 5 parts ester organic compounds, 1 to 3 parts (2-acrylamido)ethylundecyldimethylammonium bromide, 0.5 to 1.0 parts initiator, and 65 to 75 parts water, wherein the water may be purified water or distilled water.

[0026] Example 4: As an optimization of the above example, (2-acrylamido)ethylundecyldimethylammonium bromide comprises, by weight, 15 to 25 parts of ethanol, 4 to 6 parts of N,N-dimethylacrylethylenediamine, 9 to 10 parts of undecyl bromide, and 0.4 to 0.6 parts of sodium hydroxide, wherein N,N-dimethylacrylethylenediamine is obtained by reacting N,N-dimethylethylenediamine, carbon tetrachloride, sodium carbonate, and acrylyl chloride.

[0027] Example 5: As an optimization of the above examples, the ester organic compound is one of perfluorooctyl ethyl acrylate, dodecylfluoroheptyl acrylate and 1H,1H,7H-dodecylfluoroheptyl acrylate.

[0028] Example 6: As an optimization of the above example, the initiator is a mixture of sodium bisulfite and potassium persulfate in a mass ratio of 1:(5 to 6).

[0029] Example 7: As an optimization of the above examples, modified polyacrylamide was obtained by the following method: Preparation of S1,N,N-dimethylacrylamide: S11, after mixing 4 to 6 parts of N,N-dimethylethylenediamine, 10 to 20 parts of carbon tetrachloride and 0.4 to 0.6 parts of sodium carbonate, a mixture is obtained; S12, dissolve 6 to 7 parts of acryloyl chloride in 10 to 20 parts of carbon tetrachloride to obtain a carbon tetrachloride solution containing acryloyl chloride; S13, after adding a carbon tetrachloride solution containing acryloyl chloride to the mixture and mixing and reacting, reaction product a is obtained. After filtering and washing, N,N-dimethylacryloylethylenediamine is obtained. Preparation of S2, (2-acrylamido)ethylundecyldimethylammonium bromide: S21, after mixing the required amounts of ethanol, N,N-dimethylacrylamide, undecane bromide and sodium hydroxide and reacting, reaction product b is obtained; S22, reaction product b was successively cooled, precipitated with diethyl ether, washed, dried and recrystallized with ethyl acetate to obtain (2-acrylamido)ethylundecyldimethylammonium bromide; S3, Preparation of modified polyacrylamide: S31. Add the required amount of acrylamide, sodium perfluorononenoxybenzenesulfonate, ester organic matter, and (2-acrylamido)ethylundecyldimethylammonium bromide to the required amount of water and stir until completely dissolved to obtain a mixed solution. Adjust the pH value of the mixed solution. S32, under a nitrogen atmosphere, the required amount of initiator is added to the mixed solution and a polymerization reaction is carried out to obtain reaction product c. After drying, crushing, washing and drying again, reaction product c is obtained as modified polyacrylamide.

[0030] Example 8: As an optimization of the above example, in step S13, the reaction temperature is 0°C to 5°C and the reaction time is 2.0h to 2.5h.

[0031] Example 9: As an optimization of the above example, in step S22, the reaction temperature is 50°C to 55°C and the reaction time is 70h to 75h.

[0032] Example 10: As an optimization of the above example, in step S32, the reaction temperature is 40°C to 50°C and the reaction time is 12h to 14h.

[0033] Example 11: As an optimization of the above example, the discharge aid is one or more of sodium perfluorononenoxybenzenesulfonate, hexafluoropropylene oxide trimer, perfluorohexylethanol polyoxyethylene ether, and perfluorononenyl trifluoroethyl ether.

[0034] Example 12: As an optimization of the above examples, the suspending agent is one or more of nano-silica, nano-titanium dioxide, nano-alumina and nano-calcium carbonate.

[0035] Example 13: As an optimization of the above examples, the organic compound is one or more of polydimethylammonium chloride, ethylene glycol monomethyl ether, polyethylene glycol 200, polyethylene glycol 400 and polyethylene glycol 600.

[0036] Example 14: As an optimization of the above example, the mineralized water is a brine containing sodium ions, calcium ions and chloride ions.

[0037] Example 15: As an optimization of the above example, an aqueous suspension fracturing fluid is obtained by the following method: Add the required amount of modified polyacrylamide, drainage aid, xanthan gum, suspending agent and organic matter to the required amount of mineralized water, stir evenly and let stand to obtain an aqueous suspension fracturing fluid. During stirring, the stirring temperature is 30°C to 35°C and the stirring time is 30 min to 35 min. During standing, the standing temperature is 30°C to 35°C and the standing time is 4.0 h to 4.5 h.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: First, in this invention, a fluorocarbon chain is introduced into the modified polyacrylamide molecule. Compared with hydrocarbon chains of the same length, the modified polyacrylamide has a lower cohesive energy density and surface energy, and the hydrophobic association is stronger than that of hydrocarbon chains. This strengthens the intermolecular association and thus improves the viscosity-enhancing effect and salt resistance of the aqueous suspension fracturing fluid. Secondly, in this invention, quaternary ammonium salt groups are introduced into the modified polyacrylamide molecules, which can improve the solubility of the modified polyacrylamide in water, achieve the effect of rapid dissolution of the modified polyacrylamide, and facilitate the convenient preparation of aqueous suspension fracturing fluid. Third, in this invention, a suspending agent is added to the aqueous suspension fracturing fluid. The suspending agent is a nano-inorganic material. Since the nano-inorganic material is an ultrafine solid powder with a large specific surface area, it forms a stronger adsorption effect with the modified polyacrylamide, which can enhance the dimensional stability of the aqueous suspension fracturing fluid and increase the viscosity of the aqueous suspension fracturing fluid. Fourth, in this invention, mineralized water is used to prepare aqueous suspension fracturing fluid. Under high salinity, the aqueous suspension fracturing fluid can still maintain a high apparent viscosity, greater than 70 mPa·s. After adding a breaker to the aqueous suspension fracturing fluid, the resulting breaker fluid has a breaker time of less than 3 hours, an apparent viscosity of less than 5 mPa·s, a surface tension of less than 28 mN / m, and an interfacial tension between the breaker fluid and kerosene of less than 2 mN / m, all of which meet the requirements of industry standards.

[0039] Example 16: The modified polyacrylamide was obtained by the following method: Preparation of S1,N,N-dimethylacrylamide: S11, after mixing 5g of N,N-dimethylethylenediamine, 15g of carbon tetrachloride and 0.5g of sodium carbonate, a mixture is obtained; S12, 6.16g of acryloyl chloride was dissolved in 15g of carbon tetrachloride to obtain a carbon tetrachloride solution containing acryloyl chloride; S13, control the temperature below 5℃, add carbon tetrachloride solution containing acryloyl chloride dropwise to the mixture, react for 2.0h after the addition is completed to obtain reaction product a, filter reaction product a, wash with acetone aqueous solution and acetone respectively, and after filtration, obtain white solid, which is N,N-dimethylacryloylethylenediamine; Preparation of S2, (2-acrylamido)ethylundecyldimethylammonium bromide: S22, 20g ethanol, 5g N,N-dimethylacrylamide, 9.92g undecane bromide and 0.5g sodium hydroxide (as catalyst) were mixed and reacted at 52℃ for 72h to obtain reaction product b; S22, the reaction product b was cooled to room temperature, precipitated with diethyl ether to obtain white crystals, washed several times with aqueous acetone, dried, and recrystallized with ethyl acetate to obtain (2-acrylamido)ethylundecyldimethylammonium bromide. S3, Preparation of modified polyacrylamide: S31. Add 20g acrylamide, 4g sodium perfluorononenoxybenzenesulfonate, 4g ester organic compound (perfluorooctyl ethyl acrylate), and 2g (2-acrylamido) ethyl undecyl dimethyl ammonium bromide to 70g water and stir until completely dissolved to obtain a mixed solution. Adjust the pH of the mixed solution to neutral with ammonia water. S32, under a nitrogen atmosphere, 0.74g of initiator (0.12g sodium bisulfite and 0.62g potassium persulfate) was added to the mixed solution, and the polymerization reaction was carried out at a constant temperature of 45℃ for 12h to obtain reaction product c. The reaction product c was dried, pulverized, washed with acetone and anhydrous ethanol respectively, and then dried again to obtain modified polyacrylamide.

[0040] This aqueous suspension fracturing fluid comprises, by weight percentage, 0.5% modified ammonium polyacrylate, 1% flow aid (sodium perfluorononenoxybenzenesulfonate), 5% xanthan gum, 3% suspending agent (nano silica), 15% organic matter (ethylene glycol monomethyl ether), and 75.5% mineralized water. It is obtained by adding the required amounts of modified polyacrylamide, flow aid, xanthan gum, suspending agent, and organic matter to the required amount of mineralized water. The mixture is stirred for 30 minutes at a water bath temperature of 30°C and a rotation speed of 700 r / min. After stirring, it is placed in a 30°C constant temperature water bath and allowed to stand for 4 hours (to allow its viscosity to stabilize), thus obtaining the aqueous suspension fracturing fluid.

[0041] The modified ammonium polyacrylate prepared in Example 16 of this invention has the structural formula of the above-mentioned structural formula 1.

[0042] Example 17: The difference between this modified polyacrylamide and the modified polyacrylamide preparation method in Example 16 of this invention is that "9.92g undecane bromide" in step S22 is changed to "14.07g octadecane bromide", while the other raw materials and steps are the same as in Example 16.

[0043] The preparation method of this aqueous suspension fracturing fluid is the same as that of the aqueous suspension fracturing fluid in Example 16 of this invention.

[0044] The modified ammonium polyacrylate prepared in Example 17 of this invention has the structural formula of the above-mentioned structural formula 5.

[0045] Example 18: The difference between this modified polyacrylamide and the modified polyacrylamide preparation method in Example 16 of this invention is that the "4g ester organic compound (perfluorooctyl ethyl acrylate)" in step S31 is changed to "4g ester organic compound (dodecylfluoroheptyl acrylate)", while the other raw materials and steps are the same as in Example 16.

[0046] The preparation method of this aqueous suspension fracturing fluid is the same as that of the aqueous suspension fracturing fluid in Example 16 of this invention.

[0047] The modified ammonium polyacrylate prepared in Example 18 of this invention has the structural formula of the above-mentioned structural formula 2.

[0048] Example 19: The difference between this modified polyacrylamide and the modified polyacrylamide preparation method in Example 16 of this invention is that the "4g ester organic compound (perfluorooctyl ethyl acrylate)" in step S31 is modified to "4g ester organic compound (1H,1H,7H-dodecylfluoroheptyl acrylate)", while the other raw materials and steps are the same as in Example 16.

[0049] The preparation method of this aqueous suspension fracturing fluid is the same as that of the aqueous suspension fracturing fluid in Example 16 of this invention.

[0050] The modified ammonium polyacrylate prepared in Example 19 of this invention has the structural formula of the above-mentioned structural formula 3.

[0051] Comparative example: Preparation of this polyacrylamide: S31. Add 30g of acrylamide to 70g of water and stir until completely dissolved to obtain a mixed solution. Adjust the pH of the mixed solution to neutral using ammonia. S32, under a nitrogen atmosphere, 0.74 g of initiator (0.12 g sodium bisulfite and 0.62 g potassium persulfate) was added to a mixed solution, and the polymerization reaction was carried out at a constant temperature of 45 °C for 12 h to obtain the product. The product was dried, pulverized, washed with acetone and anhydrous ethanol respectively, and then dried again to obtain polyacrylamide.

[0052] The existing polyacrylamide fracturing fluid comprises 0.5% ammonium polyacrylate and 99.5% mineralized water by weight percentage. It is obtained by adding the required amount of polyacrylamide to the required amount of mineralized water and stirring for 30 minutes at a water bath temperature of 30°C and a rotation speed of 700 r / min. After stirring, it is placed in a 30°C constant temperature water bath and left to stand for 4 hours (to allow its viscosity to stabilize) to obtain the existing polyacrylamide fracturing fluid.

[0053] The mineralized water in the above embodiments is a brine containing sodium ions, calcium ions and chloride ions. The sodium ion concentration in the brine is 20 g / L, the calcium ion concentration is 15 g / L and the chloride ion concentration is 57.43 g / L, and the total mineralization is 92.43 g / L.

[0054] Experimental Example 1: The performance of the aqueous suspension fracturing fluid of the present invention was investigated.

[0055] Experimental Methods: The performance of the aqueous suspension fracturing fluids prepared in Examples 16 to 19 of this invention was examined according to the methods specified in SY / T6376-2008 "General Technical Conditions for Fracturing Fluids". The aqueous suspension fracturing fluids prepared in Examples 16 to 19 of this invention were subjected to a temperature of 120℃ and a shear rate of 170 s⁻¹. -1 Under shearing conditions for 2 hours, the apparent viscosity of the aqueous suspension fracturing fluid was measured. The temperature was then maintained at 120℃, and a breaker (ammonium persulfate) with a mass concentration of 0.2% was added to the sheared aqueous suspension fracturing fluid to obtain a broken fluid. The breaking time, apparent viscosity, surface tension, and interfacial tension between the broken fluid and kerosene were measured.

[0056] Experimental Results: The performance of the aqueous suspension fracturing fluid of the present invention is shown in Table 1. As can be seen from Table 1, compared with the comparative examples, the aqueous suspension fracturing fluids prepared in Examples 16 to 19 of the present invention have an apparent viscosity greater than 70 mPa·s, a gel breaking time of less than 3 hours, an apparent viscosity lower than 5 mPa·s, a surface tension lower than 28 mN / m, and an interfacial tension between the gel breaking fluid and kerosene lower than 2 mN / m. All of these meet the requirements of the industry standard SY / T6376-2008 "General Technical Conditions for Fracturing Fluids," while the existing polyacrylamide fracturing fluids prepared in the comparative examples do not meet these requirements. Therefore, the performance of the aqueous suspension fracturing fluid of the present invention is superior to that of existing polyacrylamide fracturing fluids.

[0057] In summary, this invention provides an aqueous suspension fracturing fluid prepared from modified polyacrylamide as a raw material, compounded with drainage aids, xanthan gum, suspending agents, organic matter, and highly salinized water. This fluid exhibits high viscosity under high salinity. Furthermore, the breaker fluid, after adding a breaker to the aqueous suspension fracturing fluid, exhibits a breaker time of less than 3 hours, an apparent viscosity below 5 mPa·s, a surface tension below 28 mN / m, and an interfacial tension between the breaker fluid and kerosene below 2 mN / m, all meeting industry standards and significantly improving the fracturing operation progress and effectiveness.

[0058] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. An aqueous suspension fracturing fluid, characterized in that... The raw materials, by weight percentage, include 0.3% to 1.5% modified ammonium polyacrylate, 1% to 5% drainage aid, 5% to 10% xanthan gum, 3% to 6% suspending agent, 1% to 20% organic matter, and the balance mineralized water.

2. The aqueous suspension fracturing fluid according to claim 1, characterized in that... Modified polyacrylamide, its structural formula is as follows: Wherein, R1 is an alkane group with 1 to 10 carbon atoms and containing F; R2 is an alkane group with 1 to 5 carbon atoms; R3 is a straight-chain alkane group with 1 to 18 carbon atoms; X is a halogen; a, b, c, and d are the molar percentages of the monomers, where a is 80% to 97%, b is 1% to 10%, c is 1% to 5%, and d is 1% to 5%.

3. The aqueous suspension fracturing fluid according to claim 1 or 2, characterized in that... Modified polyacrylamide, the raw materials comprising, by weight, 15 to 25 parts acrylamide, 3 to 5 parts sodium perfluorononenoxybenzenesulfonate, 3 to 5 parts ester organic compounds, 1 to 3 parts (2-acrylamido)ethylundecyldimethylammonium bromide, 0.5 to 1.0 parts initiator and 65 to 75 parts water.

4. The aqueous suspension fracturing fluid according to claim 3, characterized in that... (2-Acrylamido)ethylundecyldimethylammonium bromide, comprising, by weight, 15 to 25 parts ethanol, 4 to 6 parts N,N-dimethylacrylethylenediamine, 9 to 10 parts undecyl bromide and 0.4 to 0.6 parts sodium hydroxide, wherein N,N-dimethylacrylethylenediamine is obtained by reacting N,N-dimethylethylenediamine, carbon tetrachloride, sodium carbonate and acrylyl chloride.

5. The aqueous suspension fracturing fluid according to claim 3 or 4, characterized in that... The ester organic compound is one of perfluorooctyl ethyl acrylate, dodecylfluoroheptyl acrylate and 1H,1H,7H-dodecylfluoroheptyl acrylate; or / and the initiator is a mixture of sodium bisulfite and potassium persulfate in a mass ratio of 1:5 to 6.

6. The aqueous suspension fracturing fluid according to claim 4 or 5, characterized in that... Modified polyacrylamide is obtained by the following method: Preparation of S1,N,N-dimethylacrylamide: S11, after mixing 4 to 6 parts of N,N-dimethylethylenediamine, 10 to 20 parts of carbon tetrachloride and 0.4 to 0.6 parts of sodium carbonate, a mixture is obtained; S12, dissolve 6 to 7 parts of acryloyl chloride in 10 to 20 parts of carbon tetrachloride to obtain a carbon tetrachloride solution containing acryloyl chloride; S13, after adding a carbon tetrachloride solution containing acryloyl chloride to the mixture and mixing and reacting, reaction product a is obtained. After filtering and washing, N,N-dimethylacryloylethylenediamine is obtained. Preparation of S2, (2-acrylamido)ethylundecyldimethylammonium bromide: S21, after mixing the required amounts of ethanol, N,N-dimethylacrylamide, undecane bromide and sodium hydroxide and reacting, reaction product b is obtained; S22, reaction product b was successively cooled, precipitated with diethyl ether, washed, dried and recrystallized with ethyl acetate to obtain (2-acrylamido)ethylundecyldimethylammonium bromide; S3, Preparation of modified polyacrylamide: S31. Add the required amount of acrylamide, sodium perfluorononenoxybenzenesulfonate, ester organic matter, and (2-acrylamido)ethylundecyldimethylammonium bromide to the required amount of water and stir until dissolved to obtain a mixed solution. Adjust the pH value of the mixed solution. S32, under a nitrogen atmosphere, the required amount of initiator is added to the mixed solution and a polymerization reaction is carried out to obtain reaction product c. After drying, crushing, washing and drying again, reaction product c is obtained as modified polyacrylamide.

7. The aqueous suspension fracturing fluid according to claim 6, characterized in that... In step S13, the reaction temperature is 0°C to 5°C and the reaction time is 2.0h to 2.5h; or / and in step S22, the reaction temperature is 50°C to 55°C and the reaction time is 70h to 75h; or / and in step S32, the reaction temperature is 40°C to 50°C and the reaction time is 12h to 14h.

8. The aqueous suspension fracturing fluid according to any one of claims 1 to 7, characterized in that... The drainage aid is one or more of sodium perfluorononenoxybenzenesulfonate, hexafluoropropylene oxide trimer, perfluorohexylethanol polyoxyethylene ether, and perfluorononenyl trifluoroethyl ether; or / and the suspending agent is one or more of nano-silica, nano-titanium dioxide, nano-alumina, and nano-calcium carbonate; or / and the organic matter is one or more of polydienedimethylammonium chloride, ethylene glycol monomethyl ether, polyethylene glycol 200, polyethylene glycol 400, and polyethylene glycol 600; or / and the mineralized water is a brine containing sodium ions, calcium ions, and chloride ions.

9. The aqueous suspension fracturing fluid according to any one of claims 1 to 8, characterized in that... The following method is used to obtain an aqueous suspension fracturing fluid: Modified polyacrylamide, drainage aid, xanthan gum, suspending agent, and organic matter are added to the required amount of mineralized water, stirred evenly, and allowed to stand. During stirring, the temperature is 30°C to 35°C, and the stirring time is 30 to 35 minutes. During standing, the temperature is 30°C to 35°C, and the standing time is 4.0 to 4.5 hours.

10. A method for preparing an aqueous suspension fracturing fluid according to any one of claims 1 to 8, characterized in that... The following method is used: Add the required amount of modified polyacrylamide, drainage aid, xanthan gum, suspending agent and organic matter to the required amount of mineralized water, stir evenly and let stand to obtain an aqueous suspension fracturing fluid. During stirring, the stirring temperature is 30℃ to 35℃ and the stirring time is 30 min to 35 min. During standing, the standing temperature is 30℃ to 35℃ and the standing time is 4.0 h to 4.5 h.

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