A fracturing bactericide and its synthesis method and application

Abstract

The present invention belongs to the technical field of oilfield wastewater treatment, and specifically relates to a fracturing bactericide and its synthesis method and application. The synthesis method is as follows: add isopropanol, dodecyl primary phosphine, and dichloroethyl ether to a four-necked flask, stir, adjust pH7-8 at the same time, react for 0.5-2h, and heat to reflux to obtain a mixed solution; add distilled water to the mixed solution, fully oscillate, separate the liquid, discard the aqueous phase, and the oil phase is a water-containing emulsion; transfer the emulsion to a four-necked flask with isopropanol, add 1,3-dibromopropane, and heat to reflux; distill under reduced pressure, recrystallize, obtain an off-white solid, and dry to obtain a product fracturing bactericide. The fracturing bactericide has a good bactericidal effect, and the 72h viscosity retention rate of the guar gum base liquid configured with a concentration of 10mg / L bactericide reaches more than 99%; at the same time, the fracturing bactericide has the advantages of broad-spectrum bactericidal and small dosage.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield sewage treatment, and specifically relates to a fracturing bactericide and a synthesis method and application thereof. Background Art

[0002] Fracturing is a conventional process to artificially create cracks in the formation, improve the flow environment of oil underground, and increase the production of oil wells. It plays an important role in improving the flow conditions at the bottom of the oil well, slowing down the interlayer and improving the production of oil layers. Fracturing has been rapidly developed and widely used as the main production and injection increase measure for oil and gas reservoirs.

[0003] Fracturing requires a large amount of fresh water, which affects local water resources. At the same time, the water content of oil well produced fluid is getting higher and higher. These produced water cannot be discharged and can only be injected back into the formation, resulting in a large amount of energy waste. As domestic environmental protection requirements have been significantly improved, it has gradually become a trend to prepare fracturing fluid after treating produced water.

[0004] However, produced water contains a large number of bacteria, and the plant gum thickener used in fracturing fluid is prone to breeding bacteria and deterioration, which reduces the viscosity of the gel. Bacteria not only destroy the gel by reducing the molecular weight of the polymer, but also cause formation damage when injected into the oil layer with the water-based fracturing fluid. Especially in the case of poor water quality and high temperature, the reproduction rate of bacteria is extremely high. Therefore, in the process of preparing the liquid, it is necessary to use a bactericide to kill the bacteria in the polymer aqueous solution to ensure that the gel does not deteriorate from preparation to construction, and to inhibit the growth of bacteria in the oil layer when the water-based fluid is injected.

[0005] At present, the most commonly used fungicide in oil fields is dodecyl dimethyl benzyl ammonium chloride (1227), which is a single variety. 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.

[0006] CN200810023393.2 discloses a water-insoluble quaternary phosphonium salt type bactericide and a preparation method thereof, which is prepared by using silica gel inorganic materials as carriers and surface grafting amino-quaternary phosphonium salts or quaternary ammonium-quaternary phosphonium salt functional groups with bactericidal functions. The water-insoluble quaternary phosphonium salt type bactericide provided by the present invention has excellent bactericidal activity, not only has the long-term effect of quaternary phosphonium salt type bactericidal polymers, but also has efficient, rapid and broad-spectrum bactericidal effects. Moreover, the raw material sources are wide, the cost is low, and the synthesis process is simple. The bactericide is insoluble in water, and can be reused after activation and regeneration after the bactericidal rate is reduced, and can be widely used in the sterilization and disinfection of fluid media such as various industrial and civil water and the preparation of antibacterial materials. However, when the bactericide of the invention is used as an antibacterial material, it must be limited to its scope of use by using silica gel inorganic materials as carriers. Summary of the invention

[0007] The present invention aims to provide a fracturing bactericide and its synthesis method and application in view of the deficiencies of the above-mentioned prior art. The fracturing bactericide has a good bactericidal effect, and the 72h viscosity retention rate of the guar gum base fluid configured with a concentration of 10 mg / L bactericide reaches more than 99%; at the same time, the fracturing bactericide has the advantages of broad-spectrum bactericidal and low dosage, and has a killing effect on SRB, TGB, and FB in the oilfield output fluid.

[0008] One of the purposes of the present invention is to disclose a fracturing fungicide, the molecular structure of which is as follows:

[0009]

[0010] Another object of the present invention is to disclose a method for synthesizing the above-mentioned fracturing bactericide, and the specific steps are as follows:

[0011] (1) adding isopropanol, dodecyl primary phosphine and dichloroethyl ether into a four-necked flask, stirring, and simultaneously adding dropwise 5 wt % sodium hydroxide solution to adjust the pH to 7-8, reacting for 0.5-2 h, heating under reflux to obtain a mixed solution, and replenishing the sodium hydroxide solution during the reaction to maintain the pH at 7-8;

[0012] (2) adding distilled water to the mixture, shaking thoroughly, separating the liquids, discarding the aqueous phase, repeating the water washing operation once, discarding the aqueous phase, and the oil phase is an aqueous emulsion;

[0013] (3) Transfer the emulsion to a four-necked flask with isopropanol, add 1,3-dibromopropane, and heat to reflux;

[0014] (4) The brown viscous solid was distilled under reduced pressure on a rotary evaporator, and the solid was recrystallized from ethyl acetate to obtain an off-white solid, which was dried at 105-108° C. for 6-8 h to obtain a fracturing fungicide.

[0015] In the present invention, preferably, based on 1 mole part of dodecyl primary phosphine, the amounts of dichloroethyl ether and 1,3-dibromopropane are 1-1.5 mole parts and 0.45-0.6 mole parts, respectively; preferably, based on 1 mole part of dodecyl primary phosphine, the amounts of dichloroethyl ether and 1,3-dibromopropane are 1.2-1.5 mole parts and 0.48-0.55 mole parts, respectively.

[0016] Preferably, in step (1), the weight ratio of isopropanol to dodecyl primary phosphine is 20-30:1; more preferably, the weight ratio of isopropanol to dodecyl primary phosphine is 20-25:1.

[0017] Preferably, in step (1), the reflux reaction time is 6-12 h; more preferably, the reflux reaction time is 8-10 h.

[0018] In the present invention, preferably, in step (2), the weight ratio of distilled water to dodecyl primary phosphine is 20-30:1.

[0019] In the present invention, preferably, in step (3), the weight ratio of isopropanol to dodecyl primary phosphine is 40-60:1; more preferably, the weight ratio of isopropanol to dodecyl primary phosphine is 50-60:1.

[0020] Preferably, in step (3), the reflux reaction time is 24-48 h; more preferably, the reflux reaction time is 30-38 h.

[0021] The reaction equation for the synthesis of the fracturing bactericide of the present invention is as follows:

[0022]

[0023] The third object of the present invention is to disclose the application of the above-mentioned fracturing bactericide in reservoir fracturing sterilization.

[0024] The fracturing bactericide of the present invention is a diquaternary phosphonium salt with a structure similar to morpholine, with a larger phosphorus atom radius and lower electronegativity, so the quaternary phosphonium salt has a strong positive charge. The bacterial surface is negatively charged, and the quaternary phosphonium salt is easily adsorbed to the bacterial cell, and can form hydrogen bonds with the bases of deoxyribonucleic acid (DNA) in the protein in the bacterial body, adsorb on the bacterial cell, destroy the DNA structure of the bacteria, and make it lose the ability to replicate and die. At the same time, the quaternary phosphonium salt can change the permeability of the cell wall, so that the components in the bacterial cell leak out and die. The water in the preparation of the fracturing fluid contains a small amount of crude oil, and some bacteria are hidden inside the crude oil, which is difficult to kill with ordinary bactericides. The dodecyl group in the molecule of the present invention is lipophilic, and the quaternary phosphonium salt molecule can enter the inside of the crude oil and react with the bacteria inside the crude oil, thereby expanding the sterilization volume. The two identical quaternary phosphonium salt functional group structures in the same molecule further enhance the bactericidal function of the molecule.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] (1) The fracturing bactericide of the present invention has a good bactericidal effect. The 72h viscosity retention rate of the guar gum base fluid prepared with a concentration of 10 mg / L bactericide reaches more than 99%, and the bactericidal rates of SRB, TGB, and FB all reach 100%;

[0027] (2) The fracturing fungicide of the present invention has a broad spectrum, can kill SRB, TGB and FB in the oil field output fluid, and has the advantage of low dosage. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with specific examples and with reference to data. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention in any way.

[0029] Embodiment 1:

[0030] (1) Add 80.8 g of isopropanol, 20 mmol of dodecyl primary phosphine, and 20 mmol of dichloroethyl ether into a four-necked flask, stir, and simultaneously add dropwise 5 wt % sodium hydroxide solution to adjust the pH to 7-8. After reacting for 0.5 h, heat and reflux for 6 h to obtain a mixed solution. During the reaction, the sodium hydroxide solution is added to maintain the pH at 7-8.

[0031] (2) Add 80.8 g of distilled water to the mixture, shake thoroughly, separate the liquids, discard the aqueous phase, repeat the water washing operation once, discard the aqueous phase, and the oil phase is an aqueous emulsion;

[0032] (3) Transfer the emulsion to a four-necked flask with 161.6 g of isopropanol, add 9 mmol of 1,3-dibromopropane, and heat under reflux for 24 h;

[0033] (4) The brown viscous solid was distilled under reduced pressure on a rotary evaporator, and the solid was recrystallized from ethyl acetate to obtain an off-white solid, which was dried at 105° C. for 6 h to obtain the product fungicide A for fracturing.

[0034] Embodiment 2:

[0035] (1) Add 121.2 g of isopropanol, 20 mmol of dodecyl primary phosphine, and 30 mmol of dichloroethyl ether into a four-necked flask, stir, and simultaneously add dropwise 5 wt % sodium hydroxide solution to adjust the pH to 7-8. After reacting for 1 hour, heat and reflux for 12 hours to obtain a mixed solution. During the reaction, the sodium hydroxide solution is added to maintain the pH at 7-8.

[0036] (2) Add 121.2 g of distilled water to the mixture, shake thoroughly, separate the liquids, discard the aqueous phase, repeat the water washing operation once, discard the aqueous phase, and the oil phase is an aqueous emulsion;

[0037] (3) Transfer the emulsion to a four-necked flask with 242.4 g of isopropanol, add 12 mmol of 1,3-dibromopropane, and heat under reflux for 48 h;

[0038] (4) The brown viscous solid was distilled under reduced pressure on a rotary evaporator, and the solid was recrystallized from ethyl acetate to obtain an off-white solid, which was dried at 108° C. for 7 h to obtain the product fungicide B for fracturing.

[0039] Embodiment 3:

[0040] (1) Add 100.4 g of isopropanol, 20 mmol of dodecyl primary phosphine, and 25 mmol of dichloroethyl ether into a four-necked flask, stir, and simultaneously add dropwise 5 wt % sodium hydroxide solution to adjust the pH to 7-8. After reacting for 2 h, heat and reflux for 8 h to obtain a mixed solution. During the reaction, the sodium hydroxide solution is added to maintain the pH at 7-8.

[0041] (2) Add 100 g of distilled water to the mixture, shake thoroughly, separate the liquids, discard the aqueous phase, repeat the water washing operation once, discard the aqueous phase, and the oil phase is an aqueous emulsion;

[0042] (3) Transfer the emulsion to a four-necked flask with 187.6 g of isopropanol, add 9.6 mmol of 1,3-dibromopropane, and heat under reflux for 28 h;

[0043] (4) The brown viscous solid was distilled under reduced pressure on a rotary evaporator, and the solid was recrystallized from ethyl acetate to obtain an off-white solid, which was dried at 106° C. for 7 h to obtain the product fungicide C for fracturing.

[0044] Embodiment 4:

[0045] (1) Add 110.2 g of isopropanol, 20 mmol of dodecyl primary phosphine, and 28 mmol of dichloroethyl ether into a four-necked flask, stir, and simultaneously add dropwise 5 wt % sodium hydroxide solution to adjust the pH to 7-8. After reacting for 1.5 h, heat and reflux for 11 h to obtain a mixed solution. During the reaction, the sodium hydroxide solution is added to maintain the pH at 7-8.

[0046] (2) Add 101.5 g of distilled water to the mixture, shake thoroughly, separate the liquids, discard the aqueous phase, repeat the water washing operation once, discard the aqueous phase, and the oil phase is an aqueous emulsion;

[0047] (3) Transfer the emulsion to a four-necked flask with 220.3 g of isopropanol, add 11 mmol of 1,3-dibromopropane, and heat under reflux for 36 h;

[0048] (4) The brown viscous solid was distilled under reduced pressure on a rotary evaporator, and then recrystallized into an off-white solid through ethyl acetate. The solid was dried at 107° C. for 8 h to obtain the product fungicide D for fracturing.

[0049] Embodiment 5:

[0050] (1) Add 105.6 g of isopropanol, 20 mmol of dodecyl primary phosphine, and 22 mmol of dichloroethyl ether into a four-necked flask, stir, and simultaneously add dropwise 5 wt % sodium hydroxide solution to adjust the pH to 7-8. After reacting for 1.2 h, heat and reflux for 9 h to obtain a mixed solution. During the reaction, the sodium hydroxide solution is added to maintain the pH at 7-8.

[0051] (2) Add 101.2 g of distilled water to the mixture, shake thoroughly, separate the liquids, discard the aqueous phase, repeat the water washing operation once, discard the aqueous phase, and the oil phase is an aqueous emulsion;

[0052] (3) Transfer the emulsion to a four-necked flask with 200 g of isopropanol, add 9.8 mmol of 1,3-dibromopropane, and heat under reflux for 32 h;

[0053] (4) The brown viscous solid was distilled under reduced pressure on a rotary evaporator, and then recrystallized from ethyl acetate to obtain an off-white solid, which was dried at 106° C. for 6 h to obtain the product fungicide E for fracturing.

[0054] Embodiment 6:

[0055] (1) Add 108.8 g of isopropanol, 20 mmol of dodecyl primary phosphine, and 26 mmol of dichloroethyl ether into a four-necked flask, stir, and simultaneously add dropwise 5 wt % sodium hydroxide solution to adjust the pH to 7-8. After reacting for 1 hour, heat and reflux for 10 hours to obtain a mixed solution. During the reaction, the sodium hydroxide solution is added to maintain the pH at 7-8.

[0056] (2) Add 98.5 g of distilled water to the mixture, shake thoroughly, separate the liquids, discard the aqueous phase, repeat the water washing operation once, discard the aqueous phase, and the oil phase is an aqueous emulsion;

[0057] (3) Transfer the emulsion to a four-necked flask with 230.4 g of isopropanol, add 10.2 mmol of 1,3-dibromopropane, and heat under reflux for 38 h;

[0058] (4) The brown viscous solid was distilled under reduced pressure on a rotary evaporator, and then recrystallized into an off-white solid through ethyl acetate. The solid was dried at 105° C. for 7 h to obtain the product fungicide F for fracturing.

[0059] Example 7: Evaluation of Viscosity Retention of Fracturing Fluid

[0060] Refer to the method of Q / GRLH 011-2020 "Fungicide Surfactant LH-8004 for Fracturing" to evaluate the bactericidal effect.

[0061] The reinjection water treated by a joint station of Shengli Oilfield was used to prepare 0.5wt% guar gum base liquid, which was divided into several portions, each 500ml, and different concentrations of fungicides were added. The mixture was stirred evenly, and a sample without fungicide was set aside as a blank.

[0062] All samples were placed in a 30°C constant temperature water bath at the same time. The viscosity of the blank sample was tested after 4 hours, and the viscosity of the sample was tested after 72 hours. The ratio of the viscosity value of the sample to the blank sample was the viscosity retention rate. The test results are shown in Table 1.

[0063] Table 1 Fracturing fluid viscosity retention effect (viscosity retention rate, %)

[0064]

[0065]

[0066] It can be seen from Table 1 that when the mass concentration of fracturing fungicides A, B, C, D, E, and F is 5wt%, the viscosity retention rate of the fracturing fluid for 72 hours reaches more than 92%, the viscosity retention rate of the fracturing fluid fungicide F is as high as 95.8%, while the viscosity retention rate of 1227 is 51.3%, which is significantly lower than that of the present invention; when the mass concentration of fracturing fungicides A, B, C, D, E, and F is 10wt%, the viscosity retention rate of the fracturing fluid for 72 hours all reaches more than 99%, while the viscosity retention rate of 1227 is 77.8%, which is 20 percentage points lower than that of the present invention.

[0067] Example 8: Evaluation of sterilization rate

[0068] 100 ml of fracturing flowback fluid from a well in Changqing Oilfield was added to a series of narrow-necked bottles, which contained 450 SRB (sulfate-reducing bacteria) / ml, 110 TGB (saprophytic bacteria) / ml, and 45 FB (iron bacteria) / ml. Different concentrations of fungicides were added, shaken, and placed in a 50°C oven. Samples were taken after 1 hour, and the three-tube method MPN was used to detect the remaining bacterial content and calculate the sterilization rate. The test results are shown in Tables 2, 3, and 4.

[0069] Table 2 SRB sterilization results (sterilization rate, %)

[0070]

[0071]

[0072] Table 3 TGB sterilization results (sterilization rate, %)

[0073] Concentration, mg / L 5 10 15 A 97.3 100 100 B 99 100 100 C 99 100 100 D 99.4 100 100 E 99.4 100 100 F 100 100 100 1227 59.1 77.3 94.1

[0074] Table 4 FB sterilization results (sterilization rate, %)

[0075] Concentration, mg / L 5 10 15 A 98.7 100 100 B 99.3 100 100 C 99.3 100 100 D 100 100 100 E 100 100 100 F 100 100 100 1227 59.1 95.6 98.7

[0076] It can be seen from Table 1 that the fracturing fungicide A, B, C, D, E, and F of the present invention have a sterilization rate of more than 93% on SRB when the concentration is 5 mg / L, and the highest reaches 99.3% (E and F); the sterilization rate of SRB reaches 100% when the concentration is 10 mg / L or above; and the sterilization rate of 1227 on SRB is 33.3% when the concentration is 5 mg / L, and 44.4% when the concentration is 10 mg / L. Compared with the existing fungicides, the fracturing fungicide of the present invention has a good sterilization effect on SRB.

[0077] It can be seen from Table 2 that the fracturing fungicides A, B, C, D, E, and F of the present invention have a sterilization rate of more than 97% on TGB when the concentration is 5 mg / L, and the highest reaches 100% (F); the sterilization rate of TGB when the concentration is 10 mg / L and above is 100%; and the sterilization rate of 1227 is 59.1% on TGB when the concentration is 5 mg / L, and the sterilization rate of TGB when the concentration is 10 mg / L is 77.3%. Compared with the existing fracturing fungicides, the fungicides of the present invention have a good sterilization effect on TGB.

[0078] It can be seen from Table 3 that the bactericides A, B, C, D, E, and F of the present invention have a sterilization rate of more than 98% on FB when the concentration is 5 mg / L, and the highest is 100% (F); the bactericidal rate of FB is 100% when the concentration is 10 mg / L or above; and the bactericidal rate of 1227 on FB is 59.1% when the concentration is 5 mg / L, and 95.6% when the concentration is 10 mg / L. Compared with the existing fracturing bactericides, the bactericide of the present invention has a good bactericidal effect on FB.

[0079] The invented fracturing fungicide has a good bactericidal effect. The 72h viscosity retention rate of the guar gum base fluid with a concentration of 10 mg / L of the fungicide reaches more than 99%, and the bactericidal rates of SRB, TGB, and FB all reach 100%. The invented fracturing fungicide has a broad spectrum, has a killing effect on SRB, TGB, and FB in the oil field output fluid, and has the advantage of low dosage. Therefore, the invented fracturing fungicide has broad application prospects.

[0080] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for synthesizing a fungicide for fracturing, characterized in that: The synthetic method is as follows: (1) Add isopropanol, dodecyl primary phosphine and dichloroethyl ether into a four-necked flask, stir, and simultaneously add dropwise 5 wt% sodium hydroxide solution to adjust the pH to 7-8. After reacting for 0.5-2 h, heat under reflux to obtain a mixed solution. During the reaction, add the sodium hydroxide solution to maintain the pH at 7-8. (2) Add distilled water to the mixture, shake thoroughly, separate the liquids, discard the aqueous phase, repeat the water washing operation once, discard the aqueous phase, and the oil phase is an emulsion containing water; (3) Transfer the emulsion to a four-necked flask with isopropanol, add 1,3-dibromopropane, and heat to reflux; (4) Distill under reduced pressure on a rotary evaporator to obtain a brown viscous solid, recrystallize from ethyl acetate to obtain an off-white solid, and dry at 105-108°C for 6-8h to obtain a fracturing fungicide; The molecular structure of the fracturing bactericide is as follows: .

2. The synthesis method according to claim 1, characterized in that: Based on 1 mol part of dodecyl primary phosphine, the usage amounts of dichloroethyl ether and 1,3-dibromopropane are 1-1.5 mol parts and 0.45-0.6 mol parts respectively.

3. The synthesis method according to claim 2, characterized in that: Based on 1 mole of dodecyl primary phosphine, the usage of dichloroethyl ether and 1,3-dibromopropane are 1.2-1.5 mole and 0.48-0.55 mole, respectively.

4. The synthesis method according to claim 1, characterized in that: In step (1), the weight ratio of isopropanol to dodecyl primary phosphine is 20-30:

1.

5. The synthesis method according to claim 1, characterized in that: In step (1), the reflux reaction time is 6-12 hours.

6. The synthesis method according to claim 1, characterized in that: In step (2), the weight ratio of distilled water to dodecyl primary phosphine is 20-30:

1.

7. The synthesis method according to claim 1, characterized in that: In step (3), the weight ratio of isopropanol to dodecyl primary phosphine is 40-60:

1.

8. The synthesis method according to claim 1, characterized in that: In step (3), the reflux reaction time is 24-48 hours.

9. The fracturing fungicide prepared by the synthesis method according to any one of claims 1 to 8, characterized in that: The molecular structure of the fracturing bactericide is as follows: .

10. The use of the fracturing bactericide according to claim 9, characterized in that: The application is application in oil reservoir fracturing sterilization.

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