Temperature-resistant anti-swelling agent for fracturing and preparation process of temperature-resistant anti-swelling agent

Abstract

The invention relates to the technical field of petrochemical engineering, and discloses a temperature-resistant anti-swelling agent for fracturing and a preparation process thereof.The preparation method comprises the steps that glycerol triglycidyl ether and diethanol amine are subjected to a ring-opening reaction, a polyhydroxy tertiary amine monomer is obtained, then the polyhydroxy tertiary amine monomer and chloromethylated polystyrene are subjected to a quaternization reaction, and the temperature-resistant anti-swelling agent for fracturing is obtained. Quaternary ammonium salt groups of the anti-swelling agent and negative charges on the surface of clay form electrostatic interaction, and hydroxyl groups and the surface of the clay form hydrogen-bond interaction, so that the anti-swelling agent can be firmly adsorbed on the surface of the clay to form a layer of polymer film, the clay is prevented from being in contact with water, the phenomenon that the clay swells when encountering water is effectively inhibited, and the anti-swelling rate is very high. And the anti-swelling agent contains a heat-resistant polystyrene molecular chain, has excellent high temperature resistance, can maintain good structural stability at high temperature, still maintains high anti-swelling rate, and is suitable for a fracturing fluid system for high-temperature oil reservoir exploitation.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and specifically relates 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 the process of 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 efficiency of oil and gas exploitation. Therefore, a swelling inhibitor needs to be added to the fracturing fluid.

[0003] Common swelling inhibitors mainly include polyacrylamide, cationic polymers, cationic surfactants, 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 more in variety, 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 inhibitors.

[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: (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 vacuum distillation, with 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: .

[0006] (2) Add chloromethyl polystyrene and polyhydroxy tertiary amine monomer in a ratio of 1 g:(0.4 - 1.2) g to the reaction solvent, stir and react at 90 - 130 °C for 24 - 60 h. After the reaction, cool and add a poor solvent to precipitate a precipitate. Filter and wash with ethanol, and dry to obtain a temperature-resistant swelling inhibitor for fracturing. The reaction formula is: 。

[0007] Among them, the reaction solvent in (2) is N,N-dimethylformamide and / or N,N-dimethylacetamide.

[0008] Among them, the poor solvent in (2) is methanol and / or ethanol.

[0009] Among them, the preparation process of chloromethylated polystyrene is as follows: polystyrene is added to carbon tetrachloride, stannic chloride is added after stirring, 1,4-bis(chloromethoxy)butane (CAS registration number: 13483-19-7) is added dropwise, and the ratio of polystyrene, stannic chloride, and 1,4-bis(chloromethoxy)butane is controlled to be 1 g: (0.4 - 1.1) g: (3 - 10) g; the reaction is stirred at 15 - 20 °C for 6 - 15 h, diluted with hydrochloric acid solution, then ethanol is added, a precipitate is formed, and after filtration, it is washed with water and ethanol and dried to obtain chloromethylated polystyrene.

[0010] The technical effects produced 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 the tertiary amine then undergoes a quaternization reaction with chloromethylated polystyrene to obtain a temperature-resistant swelling inhibitor for fracturing. A large number of hydrophilic quaternary ammonium salt groups and hydroxyl groups are contained in this swelling inhibitor, endowing 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 swelling inhibitor 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 swelling inhibition rate. And 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 still maintains a relatively high swelling inhibition rate, and is suitable for the fracturing fluid system for high-temperature reservoir exploitation. Specific Embodiments

[0011] 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. Obviously, 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 in the present application without making creative efforts shall fall within the scope of protection of the present application.

[0012] The following polystyrene grade is GP525 and is purchased from Shanghai Hehongcheng Plastic Technology Co., Ltd.

[0013] Example 1 (1) Add 5 g of polystyrene to 70 mL of carbon tetrachloride. After stirring, add 2 g of tin tetrachloride, and then 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 a solid. Filter and wash with water and ethanol, and dry to obtain chloromethylated polystyrene.

[0014] (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, eluting with a dichloromethane and methanol solution to obtain the polyhydroxy tertiary amine monomer.

[0015] (3) Add 10 g of chloromethylated polystyrene and 4 g (6.96 mmol) of the 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 a solid. Filter and wash with ethanol, and dry to obtain the temperature-resistant swelling inhibitor for fracturing.

[0016] Example 2 (1) Add 5 g of polystyrene to 80 mL of carbon tetrachloride. After stirring, add 3.2 g of tin tetrachloride, and then 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 a solid. Filter and wash with water and ethanol, and dry to obtain chloromethylated polystyrene.

[0017] (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, eluting with a dichloromethane and methanol solution to obtain the polyhydroxy tertiary amine monomer.

[0018] (3) Add 10 g of chloromethylated polystyrene and 6.5 g of the 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 a solid. Filter and wash with ethanol, and dry to obtain the temperature-resistant swelling inhibitor for fracturing.

[0019] Example 3 (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.

[0020] (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. During the reaction, carry out condensation reflux. After the reaction, carry out vacuum distillation, separate by silica gel column chromatography, and elute with dichloromethane and methanol solution to obtain the polyhydroxy tertiary amine monomer.

[0021] (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, then dry to obtain the temperature-resistant anti-swelling agent for fracturing.

[0022] Example 4 (1) Add 5 g of polystyrene to 70 mL of carbon tetrachloride, stir and then add 5.5 g of tin tetrachloride. Dropwise add 50 g of 1,4-bis(chloromethoxy)-butane, stir and react at 15 °C for 15 h. Dilute with a hydrochloric acid solution with a mass fraction of 3.6 g / L, then add ethanol to precipitate a solid. Filter and wash with water and ethanol, then dry to obtain chloromethylated polystyrene.

[0023] (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, then dry to obtain the temperature-resistant anti-swelling agent for fracturing.

[0024] Comparative Example 1 (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, then dry to obtain the anti-swelling agent.

[0025] Comparative Example 2 (1) Add 10 g of chloromethylated polystyrene (prepared in Example 1) and 1.04 g (6.96 mmol) of triethanolamine (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, then dry to obtain the anti-swelling agent.

[0026] Comparative Example 3 (1) Add 5 g of methacryloyloxyethyl trimethyl ammonium chloride (structural formula is ), 5 mL of an aqueous solution containing 90 mg of ammonium persulfate was added dropwise, and the reaction was stirred at 75 °C for 6 h. After drying to remove water, a polyacrylate quaternary ammonium salt swelling inhibitor was obtained.

[0027] The swelling inhibitor was added to distilled water to prepare a swelling inhibitor solution with a mass concentration of 0.5 - 2 g / L, and stirred for 20 min to observe the solubility of the swelling inhibitor. The swelling inhibition rate of the swelling inhibitor solution was tested according to the method of SY / T 5971 - 2016, and the test temperature was 25 °C. The test results are shown in Tables 1 and 2.

[0028] Table 1 Water solubility test of swelling inhibitor

[0029] Table 2 Swelling inhibition performance test of swelling inhibitor

[0030] After testing, the highest swelling inhibition rate of the swelling inhibitors in Examples 1 - 4 reached 97.8%. This is mainly because the swelling inhibitors 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 swelling inhibitor to firmly adsorb on the clay surface and form a polymer film, thereby preventing the clay from contacting water and effectively inhibiting the phenomenon of clay swelling in water, showing a very high swelling inhibition rate.

[0031] Compared with Example 1, in Comparative Examples 1 and 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 in their swelling inhibitors are less than those in Example 1, and their water solubilities are 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 in their swelling inhibitors are less, and the interaction force with the clay surface is relatively low, and they do not 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.

[0032] In Comparative Example 3, common methacryloyloxyethyltrimethylammonium chloride was used as the polymerization monomer, and the highest swelling inhibition rate of the prepared polyacrylate quaternary ammonium salt swelling inhibitor reached 90.7%.

[0033] The swelling inhibitor was added to distilled water to prepare a swelling inhibitor solution with a mass concentration of 2 g / L, and stirred for 20 min. The swelling inhibition rate was tested according to the method of SY / T 5971 - 2016 at test temperatures of 25 °C and 90 °C respectively. Calculate the swelling inhibition rate retention Q. Q = W 1 / W × 100%. W 1The anti-swelling rate at 90°C is [value], and the anti-swelling rate at 25°C is [value]. The test results are shown in Table 3.

[0034] Table 3 Temperature Resistance Performance Test of Anti-Swelling Agent Solution

[0035] After testing, the anti-swelling agents of Examples 1-4 also have a high anti-swelling rate at a high temperature of 90°C, and the retention rate of the anti-swelling rate reaches 94.38-99.15%, with a relatively low decrease. This is mainly because the anti-swelling agent contains heat-resistant polystyrene molecular chains, has excellent high-temperature resistance, can maintain good structural stability at high temperatures, and has little impact on its anti-swelling performance.

[0036] The anti-swelling agents of Comparative Example 1 and Comparative Example 2 also contain heat-resistant polystyrene molecular chains, and the retention rate of the anti-swelling rate is relatively high.

[0037] The anti-swelling agent of Comparative Example 3 has a polyacrylate molecular chain, and its heat resistance is lower than that of the polystyrene molecular chain, resulting in a larger decrease in the anti-swelling rate and a low retention rate of the anti-swelling agent at a high temperature of 90°C.

[0038] 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 changes 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 process for preparing a heat-resistant anti-swelling agent for fracturing, characterized in that: The preparation process comprises: (1) adding 1 mol:(3-3.6) mol of glycerol triglycidyl ether and diethanolamine to tetrahydrofuran, distilling under reduced pressure after the reaction, and separating by silica gel column chromatography to obtain a polyhydroxy tertiary amine monomer; (2) Add chloromethyl polystyrene and polyhydroxy tertiary amine monomers in a ratio of 1 g: (0.4-1.2) g to the reaction solvent, cool the reaction, add a poor solvent, precipitate the precipitate, filter, wash, and dry to obtain a heat-resistant anti-swelling agent for fracturing.

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

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

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

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

6. The preparation process of the heat-resistant anti-swelling agent for fracturing according to claim 1, characterized in that: The preparation process of the chloromethyl polystyrene is as follows: adding polystyrene to carbon tetrachloride, adding tin tetrachloride after stirring, dropping 1,4-di(chloromethoxy)-butane, stirring and reacting at 15-20° C. for 6-15 hours, adding hydrochloric acid solution for dilution, then adding ethanol, precipitating a precipitate, filtering, washing, and drying to obtain the chloromethyl polystyrene.

7. The preparation process of the heat-resistant anti-swelling 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 heat-resistant anti-swelling agent for fracturing obtained by the preparation process according to any one of claims 1 to 7.

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