A water-based fracturing bactericide and its synthesis method

Abstract

The present invention belongs to the technical field of sewage treatment, and in particular to a water-based fracturing fungicide and a synthesis method thereof. The synthesis method comprises: 3-(di-tert-butylphosphino)propane-1-sulfonic acid and 1,4-dichloro-2-butene undergo a quaternary phosphonium reaction in a weakly alkaline solvent containing an anti-polymerization agent; secondly, in a nitrogen environment, under the action of an initiator, in an aqueous solution containing a buffer salt, the quaternary phosphonium reaction product undergoes a polymerization reaction with vinyl pyridine. The molar ratio of the 1,4-dichloro-2-butene, vinyl pyridine and 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.4-0.6:0.1-0.3:1. The water-based fracturing fungicide has the characteristics of simple synthesis process, broad sterilization spectrum and good sterilization effect.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a water-based fracturing fungicide and a synthesis method thereof. Background Art

[0002] Most domestic oil fields have entered the middle and late stages of waterflooding. Due to reservoir heterogeneity, injected water easily penetrates high-permeability layers, further increasing their permeability and causing significant water output from oil wells, impacting production capacity. To ensure uniform injection of water and improve oil recovery, the most effective method is to inject high-viscosity polymers into injection wells to adjust the water absorption profile of the wells, a process known as fracturing. This creates fractures in the formation, improving the conductivity of the oil and gas zones and ultimately increasing production.

[0003] High-viscosity polymers are typically plant-based gums, but the plant-based gums used to prepare fracturing fluids contain numerous microorganisms, such as saprophytes and yeasts. Furthermore, if the preparation tanks are not thoroughly cleaned, the residual liquid at the bottom of the tanks can breed numerous bacteria. When the environment, especially the preparation temperature, is conducive to the growth of these bacteria, the prepared plant-based gum fracturing fluid can easily spoil and deteriorate, resulting in the fluid not being cross-linked or being insufficiently cross-linked, or even being unusable for fracturing operations. Bacteria not only destroy the gel by reducing the molecular weight of the polymer but can also damage the formation when injected into the oil reservoir along with the water-based fracturing fluid. Bacteria reproduce extremely rapidly, especially in conditions of poor water quality and high temperatures. Therefore, a bactericide is required during the preparation process to kill bacteria in the polymer aqueous solution, ensuring that the gel does not spoil from preparation until construction, and to inhibit bacterial growth in the oil reservoir after the water-based fluid is injected.

[0004] Currently, the most commonly used fungicide in oil fields is dodecyl dimethyl benzyl ammonium chloride (1227). Long-term use will cause bacteria to develop a certain degree of drug resistance, resulting in a significant decrease in the effectiveness of the agent.

[0005] CN111955474A discloses a fracturing fungicide and its production process, which includes the following steps: Step 1: reacting dihexamethylenetriamine, guanidine hydrochloride, and ethylene glycol in the same reactor to obtain intermediate product A; Step 2: adding a certain amount of fatty amine, formic acid, and formaldehyde to the reaction vessel for reaction, then removing the reaction product to a container and obtaining intermediate product B; Step 3: adding acetal and SOCl2 to another reaction vessel, washing the reaction product multiple times, and finally drying the product to obtain intermediate product C; Step 4: adding intermediate product B and intermediate product C to a stirred container to obtain intermediate product D; Step 5: mixing intermediate product A and intermediate product D in a certain proportion, and adding water to prepare the fracturing fungicide. The fracturing fungicide obtained by this invention has excellent bactericidal effects on sulfate-reducing bacteria, saprophytes, and iron bacteria, and the production process is simple and mature, suitable for mass production. When the bactericide of the invention is added at a concentration of 50 mg / L, the bactericidal rate still cannot reach 100%, and the bactericidal effect needs to be improved. Summary of the Invention

[0006] In view of the deficiencies of the current existing technology, the present invention provides a water-based fracturing fungicide and a synthesis method thereof. The water-based fracturing fungicide has the characteristics of simple synthesis process, broad bactericidal spectrum and good bactericidal effect.

[0007] Therefore, in order to achieve the above-mentioned purpose, on the one hand, the present invention provides a water-based fracturing fungicide, the molecular formula of the water-based fracturing fungicide is as follows:

[0008]

[0009] Where: m = 1000-10000;

[0010] n=100-2000.

[0011] In another aspect, the present invention discloses a method for synthesizing a water-based fracturing fungicide, which comprises: conducting a quaternary phosphonium reaction between 3-(di-tert-butylphosphino)propane-1-sulfonic acid and 1,4-dichloro-2-butene in a weakly alkaline solvent containing an anti-polymerization agent; secondly, in a nitrogen environment, under the action of an initiator, the quaternary phosphonium reaction product undergoes a polymerization reaction with vinyl pyridine in an aqueous solution containing a buffer salt.

[0012] The water-based fracturing fungicide provided by the present invention is a polymer fungicide, and its monomers are unsaturated amphoteric Gemini quaternary phosphonium salt and unsaturated pyridine. The high molecular weight can help improve the fracturing effect; the quaternary phosphonium salt is a typical cationic bactericidal group with a very strong positive charge. Because the bacterial cell surface is negatively charged, it is more likely to adsorb positively charged molecules. Therefore, the fungicide molecules can penetrate into the bacteria, inactivating the bacterial proteins and achieving the purpose of sterilization. The amphoteric Gemini quaternary phosphonium salt has a stronger positive charge and a better sterilization effect; the pyridine group has the characteristics of stripping oil sludge and long-lasting sterilization; the amphoteric Gemini sulfonate has the function of assisting fracturing and oil recovery.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] (1) The water-based fracturing fungicide of the present invention has a good bactericidal effect and can kill SRB, TGB, and FB in oilfield water. Moreover, the dosage is low and the bactericidal effect is good. When the concentration is 5 mg / L, the bactericidal rate for FB can reach 100%, and when the concentration is 10 mg / L, the bactericidal rate for SRB and TGB can reach 100%.

[0015] (2) The water-based fracturing fungicide of the present invention has good antibacterial ability. When the concentration is 5 mg / L, the viscosity retention rate of the guar gum base fluid configured with the fungicide is greater than 97%, and when the concentration is 10 mg / L, the viscosity retention rate of the guar gum base fluid configured with the fungicide is greater than 99%. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0017] According to a first aspect of the present invention, the present invention provides a water-based fracturing fungicide, the molecular formula of the water-based fracturing fungicide is as follows:

[0018]

[0019] Where: m = 1000-10000;

[0020] n=100-2000.

[0021] Preferably, the viscosity-average molecular weight of the water-based fracturing fungicide is 500,000-5,000,000.

[0022] In a second aspect, the present invention discloses a method for synthesizing a water-based fracturing fungicide, the method comprising: conducting a quaternary phosphonium reaction between 3-(di-tert-butylphosphino)propane-1-sulfonic acid and 1,4-dichloro-2-butene in a weakly alkaline solvent containing an anti-polymerization agent; secondly, in a nitrogen environment, under the action of an initiator, the quaternary phosphonium reaction product undergoes a polymerization reaction with vinylpyridine in an aqueous solution containing a buffer salt.

[0023] In the present invention, preferably, the molar ratio of 1,4-dichloro-2-butene, vinyl pyridine and 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.4-0.6:0.1-0.3:1; more preferably, the molar ratio of 1,4-dichloro-2-butene, vinyl pyridine and 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.45-0.55:0.2-0.3:1.

[0024] In the present invention, preferably, the anti-polymerization agent is copper chloride or copper sulfate, and the mass ratio of the anti-polymerization agent to 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.02-0.05:1.

[0025] In the present invention, preferably, the solvent is one of methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol, and the mass ratio of the solvent to 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 15-20:1.

[0026] More preferably, the solvent is one of ethanol, isopropanol and isobutanol.

[0027] In the present invention, preferably, the weakly alkaline pH is 7.5-9.

[0028] In the present invention, preferably, the quaternary phosphonium reaction time is 12-48 hours; more preferably, the quaternary phosphonium reaction time is 18-36 hours.

[0029] In the present invention, preferably, the initiator is an aqueous solution of a mixture of persulfate and sodium bisulfite, and the mass ratio of the initiator to 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.1-0.2:1.

[0030] Preferably, the mass concentrations of the persulfate and sodium bisulfite are 6-8% and 3-4% respectively.

[0031] Preferably, the persulfate is one of potassium persulfate, sodium persulfate and ammonium persulfate.

[0032] In the present invention, preferably, the buffer salt is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate, and the mass ratio of the buffer salt to 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.05-0.2:1.

[0033] Preferably, the buffer salt is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate.

[0034] In the present invention, preferably, the mass ratio of water to 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 4-5:1.

[0035] According to a more specific preferred embodiment, the synthesis method of the water-based fracturing fungicide specifically comprises the following steps:

[0036] (1) Add 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 1,4-dichloro-2-butene, solvent, and anti-polymerization agent into a reactor, purge the reactor with nitrogen, adjust the pH to 7.5-9, and heat under reflux for 12-48 hours;

[0037] (2) distilling the mixture after heating under reflux under reduced pressure to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0038] (3) Add the light yellow solid in step (2), vinyl pyridine, water, and buffer salt to the reactor, purge the reactor with nitrogen, adjust the pH to 7.5-8, stir evenly, add the initiator dropwise, and after the addition is complete, heat to 50-60°C and keep warm for 1-2 hours to obtain a viscous liquid;

[0039] (4) Granulate the viscous liquid using a granulator to obtain a water-based fracturing fungicide with a particle size of 0.5-2 mm.

[0040] The reaction equation for the synthesis of the water-based fracturing fungicide of the present invention is as follows:

[0041]

[0042]

[0043] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0044] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0045] The technical solution of the present invention is further described below with reference to the embodiments:

[0046] Example 1

[0047] (1) Add 0.1 mol of 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 0.04 mol of 1,4-dichloro-2-butene, 402 g of methanol, and 0.54 g of copper chloride to a reactor, purge the reactor with nitrogen, adjust the pH to 9 with sodium hydroxide solution, and heat under reflux for 12 h;

[0048] (2) distilling the mixture after heating under reflux under reduced pressure to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0049] (3) Add the light yellow solid obtained in step (2), 0.01 mol of vinyl pyridine, 107 g of water, and 1.34 g of sodium dihydrogen phosphate to the reactor, purge the reactor with nitrogen, adjust the pH to 8 with sodium hydroxide solution, stir evenly, and add 2.68 g of initiator dropwise, wherein the mass concentrations of potassium persulfate and sodium bisulfite are 7.5% and 3.6%, respectively. After the addition is complete, heat to 60° C. and keep warm for 1 hour to obtain a viscous liquid;

[0050] (4) The viscous liquid is granulated using a granulator to obtain a particle size of 0.5-2 mm to obtain a water-based fracturing fungicide S1.

[0051] Example 2

[0052] (1) Add 0.1 mol of 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 0.06 mol of 1,4-dichloro-2-butene, 440 g of ethanol, and 0.58 g of copper chloride to a reactor, purge the reactor with nitrogen, adjust the pH to 7.5 with sodium hydroxide solution, and heat under reflux for 16 h;

[0053] (2) distilling the mixture after heating under reflux under reduced pressure to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0054] (3) Add the light yellow solid obtained in step (2), 0.013 mol of vinyl pyridine, 122 g of water, and 2.11 g of potassium dihydrogen phosphate to the reactor, purge the reactor with nitrogen, adjust the pH to 7.8 with sodium hydroxide solution, stir evenly, and add 2.98 g of initiator dropwise, wherein the mass concentrations of potassium persulfate and sodium bisulfite are 6.5% and 3.6%, respectively. After the addition is complete, heat to 50° C. and keep warm for 1 hour to obtain a viscous liquid;

[0055] (4) The viscous liquid is granulated using a granulator with a particle size of 0.5-2 mm to obtain a water-based fracturing fungicide S2.

[0056] Example 3

[0057] (1) Add 0.1 mol of 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 0.045 mol of 1,4-dichloro-2-butene, 484 g of n-propanol, and 0.72 g of copper chloride to a reactor, purge the reactor with nitrogen, adjust the pH to 8 with sodium hydroxide solution, and heat under reflux for 24 h;

[0058] (2) distilling the mixture under reduced pressure after heating and refluxing to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0059] (3) Add the light yellow solid obtained in step (2), 0.016 mol of vinyl pyridine, 114 g of water, and 3.03 g of ammonium dihydrogen phosphate to the reactor, purge the reactor with nitrogen, adjust the pH to 7.6 with sodium hydroxide solution, stir evenly, and dropwise add 5.12 g of initiator, wherein the mass concentrations of sodium persulfate and sodium bisulfite are 7% and 3%, respectively. After the addition is complete, heat to 55° C. and keep warm for 1.5 h to obtain a viscous liquid;

[0060] (4) The viscous liquid is granulated using a granulator with a particle size of 0.5-2 mm to obtain the product water-based fracturing fungicide S3.

[0061] Example 4

[0062] (1) Add 0.1 mol of 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 0.055 mol of 1,4-dichloro-2-butene, 462 g of n-butanol, and 0.89 g of copper chloride to a reactor, purge the reactor with nitrogen, adjust the pH to 8.5 with sodium hydroxide solution, and heat under reflux for 24 h;

[0063] (2) distilling the mixture under reduced pressure after heating and refluxing to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0064] (3) Add the light yellow solid obtained in step (2), 0.02 mol of vinyl pyridine, 118 g of water, and 3.86 g of disodium hydrogen phosphate into the reactor, purge the reactor with nitrogen, adjust the pH to 8 with sodium hydroxide solution, stir evenly, and dropwise add 4.86 g of initiator, wherein the mass concentrations of sodium persulfate and sodium bisulfite are 6% and 4%, respectively. After the addition is complete, heat to 52° C. and keep warm for 1.8 h to obtain a viscous liquid;

[0065] (4) The viscous liquid is granulated using a granulator to obtain a particle size of 0.5-2 mm to obtain a water-based fracturing fungicide S4.

[0066] Example 5

[0067] (1) Add 0.1 mol of 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 0.048 mol of 1,4-dichloro-2-butene, 492 g of isobutanol, and 1.34 g of copper sulfate to a reactor, purge the reactor with nitrogen, adjust the pH to 9 with sodium hydroxide solution, and heat under reflux for 36 h;

[0068] (2) distilling the mixture after heating under reflux under reduced pressure to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0069] (3) Add the light yellow solid obtained in step (2), 0.023 mol of vinyl pyridine, 122 g of water, and 5.36 g of dipotassium hydrogen phosphate to the reactor, purge the reactor with nitrogen, adjust the pH to 7.5 with sodium hydroxide solution, stir evenly, and add 5.36 g of initiator dropwise, wherein the mass concentrations of sodium persulfate and sodium bisulfite are 7% and 3.5%, respectively. After the addition is complete, heat to 57° C. and keep warm for 1.6 h to obtain a viscous liquid;

[0070] (4) The viscous liquid is granulated using a granulator with a particle size of 0.5-2 mm to obtain the product water-based fracturing fungicide S5.

[0071] Example 6

[0072] (1) Add 0.1 mol of 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 0.052 mol of 1,4-dichloro-2-butene, 510 g of isopropyl alcohol, and 1.21 g of copper sulfate to a reactor, purge the reactor with nitrogen, adjust the pH to 8 with sodium hydroxide solution, and heat under reflux for 48 h;

[0073] (2) distilling the mixture after heating under reflux under reduced pressure to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0074] (3) Add the light yellow solid obtained in step (2), 0.026 mol of vinyl pyridine, 129 g of water, and 4.18 g of diammonium hydrogen phosphate to the reactor, purge the reactor with nitrogen, adjust the pH to 8 with sodium hydroxide solution, stir evenly, and dropwise add 4.72 g of initiator, wherein the mass concentrations of ammonium persulfate and sodium bisulfite are 6% and 3%, respectively. After the addition is complete, heat to 53° C. and keep warm for 1.3 h to obtain a viscous liquid;

[0075] (4) The viscous liquid is granulated using a granulator to obtain a particle size of 0.5-2 mm to obtain a water-based fracturing fungicide S6.

[0076] Example 7

[0077] (1) Add 0.1 mol of 3-(di-tert-butylphosphino)propane-1-sulfonic acid, 0.05 mol of 1,4-dichloro-2-butene, 536 g of ethanol, and 1.02 g of copper chloride to a reactor, purge the reactor with nitrogen, adjust the pH to 7.5 with sodium hydroxide solution, and heat under reflux for 40 h;

[0078] (2) distilling the mixture under reduced pressure after heating and refluxing to a viscous solid, recrystallizing it with ethyl acetate, and drying it to obtain a light yellow solid;

[0079] (3) Add the light yellow solid obtained in step (2), 0.03 mol of vinyl pyridine, 134 g of water, and 5.04 g of sodium dihydrogen phosphate to the reactor, purge the reactor with nitrogen, adjust the pH to 7.5 with sodium hydroxide solution, stir evenly, and dropwise add 3.98 g of initiator, wherein the mass concentrations of ammonium persulfate and sodium bisulfite are 8% and 4%, respectively. After the addition is complete, heat to 56° C. and keep warm for 1.3 h to obtain a viscous liquid;

[0080] (4) The viscous liquid is granulated using a granulator with a particle size of 0.5-2 mm to obtain the product water-based fracturing fungicide S7.

[0081] Test Example 1 Evaluation of Sterilization Effect

[0082] In a series of narrow-necked bottles, 250 ml of untreated water sample after oil-water separation from a joint station of Shengli Oilfield was added, and fungicides of different concentrations were added. The bottles were placed in a 60°C oven and samples were taken after 1 hour. The number of SRB, TGB, and FB was detected by the extinction dilution method, and the bactericidal rate was calculated. Dodecyldimethylbenzyl ammonium chloride (1227) was used as a comparative sample.

[0083] The sterilization results of SRB are shown in Table 1, the sterilization results of TGB are shown in Table 2, and the sterilization results of FB are shown in Table 3.

[0084] Table 1 Bactericidal results of SRB by bactericides (bactericidal rate, %)

[0085] fungicides 3mg / L 5mg / L 10mg / L <![CDATA[S1]]> 75.6 99.2 100 <![CDATA[S2]]> 90 99.6 100 <![CDATA[S3]]> 90 99.7 100 <![CDATA[S4]]> 96.4 99.8 100 <![CDATA[S5]]> 93.3 99.2 100 <![CDATA[S6]]> 97.8 99.9 100 <![CDATA[S7]]> 98.7 100 100 1227 33.3 44.4 77.3

[0086] Table 2 Bactericidal results of TGB by bactericides (bactericidal rate, %)

[0087] fungicides 3mg / L 5mg / L 10mg / L <![CDATA[S1]]> 81.8 99.7 100 <![CDATA[S2]]> 90.9 99.7 100 <![CDATA[S3]]> 93.2 100 100 <![CDATA[S4]]> 96.4 100 100 <![CDATA[S5]]> 93.2 100 100 <![CDATA[S6]]> 98.2 100 100 <![CDATA[S7]]> 98.5 100 100 1227 44.4 66.7 81.8

[0088] Table 3 Bactericidal results of FB by bactericides (bactericidal rate, %)

[0089] fungicides 3mg / L 5mg / L 10mg / L <![CDATA[S1]]> 93.3 100 100 <![CDATA[S2]]> 98.4 100 100 <![CDATA[S3]]> 98.4 100 100 <![CDATA[S4]]> 98.7 100 100 <![CDATA[S5]]> 99.3 100 100 <![CDATA[S6]]> 99.3 100 100 <![CDATA[S7]]> 99.7 100 100 1227 59.1 77.3 94.1

[0090] It can be seen from Table 1 that the sterilization rates of the water-based fracturing fungicides S1, S2, S3, S4, S5, S6, and S7 of the present invention against SRB all reach more than 75% when used at a concentration of 3 mg / L, among which the sterilization rate of S7 reaches the highest, 98.7%, while the sterilization rate of the comparative fungicide 1227 is 33.3%; when used at a concentration of 5 mg / L, the sterilization rates against SRB all reach more than 99%, among which the sterilization rate of S7 reaches the highest, 100%, while the sterilization rate of the comparative fungicide 1227 is 44.4%; when used at a concentration of 10 mg / L, the sterilization rates against SRB all reach 100%, while the sterilization rate of the comparative fungicide 1227 is 77.3%, which is significantly lower than that of the present invention.

[0091] It can be seen from Table 2 that the bactericidal rates of the water-based fracturing fungicides S1, S2, S3, S4, S5, S6, and S7 of the present invention on TGB all reach more than 80% when used at a concentration of 3 mg / L, among which the bactericidal rate of S7 reaches the highest, 98.5%, while the bactericidal rate of the comparative fungicide 1227 is 44.4%; when used at a concentration of 5 mg / L, the bactericidal rates on TGB all reach more than 99%, with the highest reaching 100%, while the bactericidal rate of the comparative fungicide 1227 is 66.7%; when used at a concentration of 10 mg / L, the bactericidal rates on TGB all reach 100%, while the bactericidal rate of the comparative fungicide 1227 is 81.8%, which is significantly lower than that of the present invention.

[0092] It can be seen from Table 3 that the bactericidal rates of the water-based fracturing fungicides S1, S2, S3, S4, S5, S6, and S7 of the present invention on FB all reach more than 93% when used at a concentration of 3 mg / L, among which the bactericidal rate of S7 reaches the highest, reaching 99.7%, while the bactericidal rate of the comparative fungicide 1227 is 59.1%; when used at a concentration of 5 mg / L, the bactericidal rates on FB all reach 100%, while the bactericidal rate of the comparative fungicide 1227 is 77.3%; when used at a concentration of 10 mg / L, the bactericidal rates on FB all reach 100%, while the bactericidal rate of the comparative fungicide 1227 is 94.1%, which is significantly lower than that of the present invention.

[0093] Test Example 2: Antibacterial Ability Test

[0094] The evaluation method shall refer to Q / SH1025 0784—2011 “Technical Conditions for Fracturing Bactericides” and shall be implemented in accordance with the requirements of 5.3.

[0095] Preparation of fungicide solution: dilute the fungicide of the present invention with water to a concentration of 0.5 wt % or 1 wt %.

[0096] Preparation of base liquid: Pour 1000ml of tap water into a sterile blender. Adjust the speed of the blender until the top of the mixer's paddle axis is visible through the vortex formed by the liquid. Then, slowly add 5g (accurate to 0.001g) of guar gum and 1mL of the fungicide sample. Continue stirring for 5 minutes to form a uniform solution. Stop stirring and allow to stand in an electrically heated incubator at 30°C to maintain constant temperature.

[0097] Preparation of jelly: Measure 70 ml of the above base liquid and pour it into a 100 ml beaker. While stirring with a glass rod, add 0.35 ml of high-temperature stabilizer for fracturing and 0.30 ml of liquid sodium hydroxide in sequence, stir evenly, and then add 0.35 ml of cross-linking agent while stirring until a uniform jelly that can be hung is formed.

[0098] Viscosity measurement: Prepare gels from the base fluids that have been kept at constant temperature for 4 hours and 120 hours, respectively. Then, place them into the RT20 rheometer and measure the heat and shear resistance of the fracturing fluid according to 6.6 of SY / T 5107-2005 "Evaluation Methods for Performance of Water-Based Fracturing Fluids". Set the temperature to 120°C and the rotor at a shear rate of 170s. -1 The gel was sheared for 90 min, and the average apparent viscosity corresponding to the last 10 min of shearing was taken as the apparent viscosity of the gel.

[0099]

[0100] Where:

[0101] R—Fracturing fluid viscosity retention rate, %;

[0102] η1—apparent viscosity of the gel when the base liquid is kept at a constant temperature for 4 hours, in millipascal seconds (mPa·s);

[0103] η2—Apparent viscosity of the gel when the base liquid is kept at a constant temperature for 120 hours, in millipascal seconds (mPa·s).

[0104] Dodecyldimethylbenzyl ammonium chloride (1227) was used as a comparative sample. The antibacterial ability test results are shown in Table 4.

[0105] Table 4 Antibacterial ability test results of fungicides (adhesion retention rate, %)

[0106]

[0107]

[0108] It can be seen from Table 4 that the antibacterial abilities of the water-based fracturing fungicides S1, S2, S3, S4, S5, S6, and S7 of the present invention all reach above 97% when used at a concentration of 5 mg / L, among which the antibacterial ability of S6 reaches the highest, 98.5%, while the antibacterial ability of the comparative fungicide 1227 is 56.3%; when used at a concentration of 10 mg / L, the antibacterial abilities of all reach above 99%, among which the antibacterial ability of S6 reaches the highest, 99.5%, while the antibacterial ability of the comparative fungicide 1227 is 80.2%, which is significantly lower than that of the present invention.

[0109] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A water-based fracturing fungicide, characterized in that: The molecular formula of the water-based fracturing fungicide is as follows: Where: m = 1000-10000; n＝100-2000。 2. A water-based fracturing fungicide according to claim 1, characterized in that: The viscosity average molecular weight of the water-based fracturing fungicide is 500,000-5,000,000.

3. A method for synthesizing a water-based fracturing fungicide, characterized in that: The synthesis method comprises: performing a quaternary phosphonation reaction on 3-(di-tert-butylphosphino)propane-1-sulfonic acid and 1,4-dichloro-2-butene in a weakly alkaline solvent containing a polymerization inhibitor; then, in a nitrogen environment, under the action of an initiator, polymerizing the quaternary phosphonation reaction product with vinyl pyridine in an aqueous solution containing a buffer salt; The molar ratio of 1,4-dichloro-2-butene, vinyl pyridine and 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.4-0.6:0.1-0.3:

1.

4. The method for synthesizing a water-based fracturing fungicide according to claim 3, characterized in that: The molar ratio of 1,4-dichloro-2-butene, vinyl pyridine and 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.45-0.55:0.2-0.3:

1.

5. The method for synthesizing a water-based fracturing fungicide according to claim 3, characterized in that: The anti-agglomeration agent is copper chloride or copper sulfate, and the mass ratio of the anti-agglomeration agent to 3-(di-tert-butylphosphine)propane-1-sulfonic acid is 0.02-0.05:

1.

6. The method for synthesizing a water-based fracturing fungicide according to claim 3, characterized in that: The quaternization reaction time is 12-48 hours.

7. The method for synthesizing a water-based fracturing fungicide according to claim 3, characterized in that: The initiator is an aqueous solution of a mixture of persulfate and sodium bisulfite, and the mass ratio of the initiator to 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.1-0.2:

1.

8. The method for synthesizing a water-based fracturing fungicide according to claim 7, characterized in that: The mass concentrations of the persulfate and sodium bisulfite are 6-8% and 3-4% respectively.

9. The method for synthesizing a water-based fracturing fungicide according to claim 3, characterized in that: The buffer salt is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate, and the mass ratio of the buffer salt to 3-(di-tert-butylphosphino)propane-1-sulfonic acid is 0.05-0.2:1.

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