A temperature-resistant swelling inhibitor for fracturing and its preparation process

Abstract

The present invention relates to the technical field of petrochemical engineering, and discloses a temperature-resistant swelling inhibitor for fracturing and its preparation process. In the present invention, glycerol triglycidyl ether and diethanolamine are subjected to a ring-opening reaction to obtain a polyhydroxy tertiary amine monomer, which is then subjected to a quaternization reaction with chloromethyl polystyrene to obtain the temperature-resistant swelling inhibitor for fracturing. The quaternary ammonium salt group of the swelling inhibitor forms an electrostatic interaction with the negative charge on the clay surface, and at the same time, the hydroxyl group forms a hydrogen bond with the clay surface, enabling the swelling inhibitor to firmly adsorb on the clay surface and form a polymer film, thereby preventing the clay from contacting with water and effectively inhibiting the phenomenon of clay swelling upon contact with water, showing a very high swelling inhibition rate. Moreover, the swelling inhibitor contains a heat-resistant polystyrene molecular chain and has excellent high-temperature resistance performance. It can maintain good structural stability at high temperatures and still maintain a relatively high swelling inhibition rate, and is suitable for the fracturing fluid system for high-temperature reservoir exploitation.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and specifically to a temperature-resistant swelling inhibitor for fracturing and its preparation process. Background Art

[0002] Fracturing operation technology is an important technology for increasing oil and gas production and injection in oil and gas field exploitation. High-pressure liquid is injected into the formation to form fractures, improving the permeability of the oil and gas reservoir, thereby achieving the effect of increasing oil and gas production. However, during the fracturing operation, clay in the formation will undergo hydration swelling when encountering water, which will cause problems such as wellbore instability and reduction of formation permeability, and will affect the oil and gas exploitation efficiency. Therefore, a swelling inhibitor needs to be added to the fracturing fluid.

[0003] Common swelling inhibitors mainly include polyacrylamide, cationic polymer, cationic surfactant, etc. However, these swelling inhibitors have poor swelling prevention performance and poor high-temperature resistance, which is not conducive to their practical application in the exploitation of high-temperature oil and gas wells. The patent with publication number CN104861110B discloses a swelling inhibitor and sand control agent for high-permeability heavy oil reservoirs and its preparation method. The swelling inhibitor and sand control agent polymerized from monomers such as acrylamide or methacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, styrene, acrylonitrile, acryloyloxyethyltrimethylammonium chloride or trimethylallylammonium chloride has good swelling prevention performance and sand control performance. However, the polymerization monomers of the swelling inhibitor in this patent are of many types, and microwave heating method and ultraviolet light irradiation method are required during the reaction process, and the preparation process is relatively complex. Summary of the Invention

[0004] The present invention solves the problems of poor swelling prevention performance and poor high-temperature resistance of the existing cationic swelling inhibitor.

[0005] In order to achieve the above-mentioned invention purpose, the technical solution adopted by the present invention is: A preparation process of a temperature-resistant swelling inhibitor for fracturing:

[0006] (1) Add glycerol triglycidyl ether (CAS registration number: 13236-02-7) and diethanolamine in a ratio of 1 mol:(3 - 3.6) mol to tetrahydrofuran, stir and react at 65 - 70 °C for 6 - 10 h. After the reaction, carry out reduced pressure distillation, perform condensation reflux during the reaction, and separate by silica gel column chromatography, and elute with dichloromethane and methanol solution to obtain a polyhydroxy tertiary amine monomer. The reaction formula is:

[0007] .

[0008] (2) Add chloromethylated polystyrene and polyhydroxy tertiary amine monomer in a ratio of 1 g : (0.4 - 1.2) g to the reaction solvent, and stir and react at 90 - 130 °C for 24 - 60 h. After the reaction, cool it and add a poor solvent to precipitate a solid. Filter and wash it with ethanol, then dry it to obtain a temperature-resistant anti-swelling agent for fracturing. The reaction formula is:

[0009] .

[0010] Among them, the reaction solvent in (2) is N,N-dimethylformamide and / or N,N-dimethylacetamide.

[0011] Among them, the poor solvent in (2) is methanol and / or ethanol.

[0012] Among them, the preparation process of chloromethylated polystyrene is as follows: Add polystyrene to carbon tetrachloride, stir and then add tin tetrachloride, and dropwise add 1,4-bis(chloromethoxy)butane (CAS registration number: 13483 - 19 - 7). Control the ratio of polystyrene, tin tetrachloride, and 1,4-bis(chloromethoxy)butane to be 1 g : (0.4 - 1.1) g : (3 - 10) g; Stir and react at 15 - 20 °C for 6 - 15 h, add hydrochloric acid solution for dilution, then add ethanol to precipitate a solid. Filter and wash it with water and ethanol, then dry it to obtain chloromethylated polystyrene.

[0013] The technical effects achieved by adopting the above technical solutions: In the present invention, glycidyl ether of glycerol and diethanolamine are subjected to a ring-opening reaction to obtain a polyhydroxy tertiary amine monomer, and then the tertiary amine reacts with chloromethylated polystyrene to undergo a quaternization reaction to obtain a temperature-resistant anti-swelling agent for fracturing. This anti-swelling agent contains a large number of hydrophilic quaternary ammonium salt groups and hydroxyl groups, which endow polystyrene with excellent water solubility. At the same time, the positively charged quaternary ammonium salt groups form an electrostatic interaction with the negative charges on the clay surface, and the hydroxyl groups form a hydrogen bond interaction with the clay surface, enabling the anti-swelling agent to firmly adsorb on the clay surface and form a polymer film, thereby preventing the clay from contacting with water and effectively inhibiting the swelling phenomenon of the clay when it encounters water, showing a very high anti-swelling rate. Moreover, the anti-swelling agent contains a heat-resistant polystyrene molecular chain and has excellent high-temperature resistance. It can maintain good structural stability at high temperatures and still maintain a relatively high anti-swelling rate, and is suitable for the fracturing fluid system for high-temperature reservoir exploitation. Specific Embodiments

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0015] The following polystyrene grade is GP525 and is purchased from Shanghai Hehongcheng Plastic Technology Co., Ltd.

[0016] Example 1

[0017] (1) Add 5 g of polystyrene to 70 mL of carbon tetrachloride. After stirring, add 2 g of tin tetrachloride, and dropwise add 15 g of 1,4-bis(chloromethoxy)butane. Stir and react at 20 °C for 6 h. Add a hydrochloric acid solution with a mass fraction of 3.6 g / L for dilution, then add ethanol to precipitate the product. Filter and wash with water and ethanol, and dry to obtain chloromethylated polystyrene.

[0018] (2) Add 30 mmol of glycerol triglycidyl ether and 90 mmol of diethanolamine to 60 mL of tetrahydrofuran. Stir and react at 70 °C for 6 h with reflux condensation during the reaction. After the reaction, perform vacuum distillation and separate by silica gel column chromatography, and elute with a dichloromethane and methanol solution to obtain the polyhydroxy tertiary amine monomer.

[0019] (3) Add 10 g of chloromethylated polystyrene and 4 g (6.96 mmol) of polyhydroxy tertiary amine monomer to 100 mL of N,N-dimethylformamide. Stir and react at 110 °C for 48 h. After the reaction, cool and add methanol to precipitate the product. Filter and wash with ethanol, and dry to obtain the temperature-resistant swelling inhibitor for fracturing.

[0020] Example 2

[0021] (1) Add 5 g of polystyrene to 80 mL of carbon tetrachloride. After stirring, add 3.2 g of tin tetrachloride, and dropwise add 26 g of 1,4-bis(chloromethoxy)butane. Stir and react at 15 °C for 10 h. Add a hydrochloric acid solution with a mass fraction of 3.6 g / L for dilution, then add ethanol to precipitate the product. Filter and wash with water and ethanol, and dry to obtain chloromethylated polystyrene.

[0022] (2) Add 30 mmol of glycerol triglycidyl ether and 90 mmol of diethanolamine to 50 mL of tetrahydrofuran. Stir and react at 70 °C for 8 h with reflux condensation during the reaction. After the reaction, perform vacuum distillation and separate by silica gel column chromatography, and elute with a dichloromethane and methanol solution to obtain the polyhydroxy tertiary amine monomer.

[0023] (3) Add 10 g of chloromethylated polystyrene and 6.5 g of polyhydroxy tertiary amine monomer to 150 mL of N,N-dimethylacetamide. Stir and react at 130 °C for 24 h. After the reaction, cool and add ethanol to precipitate the product. Filter and wash with ethanol, and dry to obtain the temperature-resistant swelling inhibitor for fracturing.

[0024] Example 3

[0025] (1) Add 5 g of polystyrene to 70 mL of carbon tetrachloride. After stirring, add 4.3 g of tin tetrachloride, and then dropwise add 38 g of 1,4-bis(chloromethoxy)butane. Stir and react at 15 °C for 12 h. Add a hydrochloric acid solution with a mass fraction of 3.6 g / L for dilution, then add ethanol to precipitate a solid. Filter and wash with water and ethanol, and dry to obtain chloromethylated polystyrene.

[0026] (2) Add 30 mmol of glycerol triglycidyl ether and 108 mmol of diethanolamine to 60 mL of tetrahydrofuran. Stir and react at 65 °C for 10 h, with reflux condensation during the reaction. After the reaction, perform vacuum distillation and separate by silica gel column chromatography, eluting with a dichloromethane and methanol solution to obtain a polyhydroxy tertiary amine monomer.

[0027] (3) Add 10 g of chloromethylated polystyrene and 9.8 g of polyhydroxy tertiary amine monomer to 150 mL of N,N-dimethylformamide. Stir and react at 90 °C for 60 h. After the reaction, cool and add ethanol to precipitate a solid. Filter and wash with ethanol, and dry to obtain a temperature-resistant swelling inhibitor for fracturing.

[0028] Example 4

[0029] (1) Add 5 g of polystyrene to 70 mL of carbon tetrachloride. After stirring, add 5.5 g of tin tetrachloride, and then dropwise add 50 g of 1,4-bis(chloromethoxy)butane. Stir and react at 15 °C for 15 h. Add a hydrochloric acid solution with a mass fraction of 3.6 g / L for dilution, then add ethanol to precipitate a solid. Filter and wash with water and ethanol, and dry to obtain chloromethylated polystyrene.

[0030] (2) Add 10 g of chloromethylated polystyrene and 12 g of polyhydroxy tertiary amine monomer (prepared in Example 1) to 150 mL of N,N-dimethylformamide. Stir and react at 100 °C for 60 h. After the reaction, cool and add ethanol to precipitate a solid. Filter and wash with ethanol, and dry to obtain a temperature-resistant swelling inhibitor for fracturing.

[0031] Comparative Example 1

[0032] (1) Add 10 g of chloromethylated polystyrene (prepared in Example 1) and 0.73 g (6.96 mmol) of N-methyldiethanolamine (structural formula is ) to 100 mL of N,N-dimethylformamide. Stir and react at 110 °C for 48 h. After the reaction, cool and add methanol to precipitate a solid. Filter and wash with ethanol, and dry to obtain a swelling inhibitor.

[0033] Comparative Example 2

[0034] (1) Add 10 g of chloromethylated polystyrene (prepared in Example 1) and 1.04 g (6.96 mmol) of triethanolamine (structural formula ) to 100 mL of N,N-dimethylformamide, stir and react at 110 °C for 48 h. After the reaction, cool and add methanol. Precipitate is separated out, washed with ethanol after filtration, and dried to obtain the anti-swelling agent.

[0035] Comparative Example 3

[0036] (1) Add 5 g of methacryloyloxyethyl trimethyl ammonium chloride (structural formula ) to 20 mL of distilled water, dropwise add 5 mL of an aqueous solution containing 90 mg of ammonium persulfate, stir and react at 75 °C for 6 h, dry to remove water to obtain the polyacrylate quaternary ammonium salt anti-swelling agent.

[0037] Add the anti-swelling agent to distilled water to prepare an anti-swelling agent solution with a mass concentration of 0.5 - 2 g / L, stir for 20 min, and observe the solubility of the anti-swelling agent. And test the anti-swelling rate of the anti-swelling agent solution according to the method of SY / T 5971-2016, and the test temperature is 25 °C. The test results are shown in Tables 1 and 2.

[0038] Table 1 Water solubility test of anti-swelling agent

[0039]

[0040] Table 2 Anti-swelling performance test of anti-swelling agent

[0041]

[0042] After testing, the highest anti-swelling rate of the anti-swelling agents in Examples 1 - 4 reaches 97.8%. The main reason is that the anti-swelling agents contain a large number of hydrophilic quaternary ammonium salt groups and hydroxyl groups, which endow polystyrene with excellent water solubility. At the same time, the positively charged quaternary ammonium salt groups form electrostatic interactions with the negative charges on the clay surface, and the hydroxyl groups form hydrogen bond interactions with the clay surface, enabling the anti-swelling agent to firmly adsorb on the clay surface, forming a polymer film, thereby preventing the clay from contacting water and effectively inhibiting the phenomenon of clay swelling in water, showing a very high anti-swelling rate.

[0043] Compared with Example 1, in Comparative Example 1 and Comparative Example 2, chloromethyl polystyrene was reacted with N-methyldiethanolamine and triethanolamine. Since N-methyldiethanolamine and triethanolamine contain only one tertiary amine group and have a relatively low hydroxyl content, the hydrophilic quaternary ammonium salt groups and hydroxyl groups of the swelling inhibitors in both of them are less than those in Example 1, and their water solubility is poor. It is difficult to completely dissolve in water at high concentrations (1.5 - 2 g / L), which seriously affects the swelling inhibition rate. Moreover, the quaternary ammonium salt groups and hydroxyl groups of the swelling inhibitors in both of them are less, and the interaction force with the clay surface is low, so they cannot firmly adsorb on the clay surface to form a polymer film, resulting in the clay being easily in contact with water and swelling when encountering water, and the swelling inhibition rates are both low.

[0044] In Comparative Example 3, common methacryloyloxyethyl trimethyl ammonium chloride was used as the polymerization monomer, and the highest swelling inhibition rate of the polyacrylate quaternary ammonium salt swelling inhibitor prepared reached 90.7%.

[0045] The swelling inhibitor was added to distilled water to prepare a swelling inhibitor solution with a mass concentration of 2 g / L, and it was stirred for 20 min. The swelling inhibition rate was tested according to the method of SY / T 5971 - 2016, and the test temperatures were 25°C and 90°C respectively. The swelling inhibition rate retention Q was calculated. Q = W1 / W × 100%. W1 is the swelling inhibition rate at 90°C, and W is the swelling inhibition rate at 25°C. The test results are shown in Table 3.

[0046] Table 3 Test on the temperature resistance performance of the swelling inhibitor solution

[0047]

[0048] After testing, the swelling inhibitors of Examples 1 - 4 also have a high swelling inhibition rate at a high temperature of 90°C, and the swelling inhibition rate retention reaches 94.38 - 99.15%, with a relatively low decline rate. This is mainly because the swelling inhibitor contains a heat-resistant polystyrene molecular chain, has excellent high-temperature resistance performance, can maintain good structural stability at high temperatures, and has little impact on its swelling inhibition performance.

[0049] The swelling inhibitors of Comparative Example 1 and Comparative Example 2 also contain heat-resistant polystyrene molecular chains, and the swelling inhibition rate retention is relatively high.

[0050] The swelling inhibitor of Comparative Example 3 has a polyacrylate molecular chain, and its heat resistance is lower than that of the polystyrene molecular chain. As a result, the swelling inhibitor has a large decline in the swelling inhibition rate and a low retention rate at a high temperature of 90°C.

[0051] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation process of a temperature-resistant swelling inhibitor for fracturing, characterized in that, The preparation process includes: (1) Add glycerol triglycidyl ether and diethanolamine in a ratio of 1 mol:(3 - 3.6) mol to tetrahydrofuran. After reaction, distill under reduced pressure and separate by silica gel column chromatography to obtain a polyhydroxy tertiary amine monomer; (2) Add chloromethylated polystyrene and the polyhydroxy tertiary amine monomer prepared in step (1) in a ratio of 1 g:(0.4 - 1.2) g to the reaction solvent. After reaction, cool and add a poor solvent to precipitate a solid. Filter, wash, and dry to obtain a temperature-resistant swelling inhibitor for fracturing.

2. The preparation process of the temperature-resistant swelling inhibitor for fracturing according to claim 1, characterized in that, In (1), the reaction temperature is controlled at 65 - 70 °C and the reaction time is controlled at 6 - 10 h.

3. The preparation process of the temperature-resistant swelling inhibitor for fracturing according to claim 1, characterized in that, In (2), the reaction solvent is N,N-dimethylformamide and / or N,N-dimethylacetamide.

4. The preparation process of the temperature-resistant and swelling-preventing agent for fracturing according to claim 1, characterized in that, In (2), the poor solvent is methanol and / or ethanol.

5. The preparation process of the temperature-resistant swelling inhibitor for fracturing according to claim 1, characterized in that, In (2), the reaction temperature is 90 - 130 °C and the reaction time is 24 - 60 h.

6. The preparation process of the temperature-resistant anti-swelling agent for fracturing according to claim 1, characterized in that, The preparation process of the chloromethylated polystyrene is as follows: Add polystyrene to carbon tetrachloride, stir and then add tin tetrachloride. Dropwise add 1,4-bis(chloromethoxy)butane and stir and react at 15 - 20 °C for 6 - 15 h. Add hydrochloric acid solution for dilution, then add ethanol to precipitate a solid. Filter, wash, and dry to obtain chloromethylated polystyrene.

7. The preparation process of the temperature-resistant and swelling-preventing agent for fracturing according to claim 6, characterized in that, The ratio of the polystyrene, tin tetrachloride, and 1,4-bis(chloromethoxy)butane is 1 g:(0.4 - 1.1) g:(3 - 10) g.

8. A temperature-resistant swelling inhibitor for fracturing obtained by the preparation process according to any one of claims 1 - 7.

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