Amphophilic clay stabilizer, its preparation method and application

Abstract

The application belongs to the technical field of oil production, and particularly relates to an amphoteric clay stabilizer and a preparation method and application thereof, and comprises the following steps: acrylamide, 2-methyl-2-acrylamidopropyl sulfonic acid, dimethyldiallylammonium chloride, KH570 modified nano-SiO2 and water are added into a reaction kettle, and nitrogen is introduced; after heating, ammonium persulfate and sodium bisulfite are added, polyvinyl alcohol is added after reaction, and the mixture is naturally cooled to room temperature after polymerization to obtain the clay stabilizer; the clay stabilizer prepared by the method has excellent temperature resistance, salt resistance, acid and alkali resistance and scouring resistance, and has the advantages of long action time, small dosage and good anti-swelling effect.

Description

Technical Field

[0001] This invention belongs to the field of oil extraction technology, specifically relating to an amphoteric clay stabilizer, its preparation method, and its application. Background Technology

[0002] Clay minerals are widely present in oil-bearing reservoirs and, as an important component of oil and gas reservoirs, have a significant impact on oilfield development. At every stage of oilfield development—drilling, completion, workover, and subsequent acidizing and fracturing operations—external fluids come into contact with formation clay minerals. These external fluids, such as drilling fluids, completion fluids, workover fluids, fracturing fluids, and acidizing fluids, often differ in properties from the formation clay minerals, easily causing hydration, swelling, and dispersion of the clay minerals. This can damage the oil and gas reservoir, affecting its permeability and recovery rate.

[0003] To mitigate reservoir damage, protect the permeability of oil and gas formations, and improve oil and gas field recovery, clay stabilizers must be used to stabilize clay. The main function of clay stabilizers is to prevent water-sensitive minerals from hydrating, swelling, and migrating upon contact with external fluids, thereby effectively protecting the oil and gas reservoir. By adsorbing onto the clay surface, clay stabilizers form a monomolecular adsorption film, stabilizing clay minerals over the long term, increasing the cementation strength of the reservoir, and preventing damage to the oil and gas reservoir caused by hydration, swelling, and migration of clay minerals.

[0004] However, currently used clay stabilizers have some shortcomings. First, a short effective time is a significant issue. Many clay stabilizers become ineffective after a period of time, failing to effectively stabilize clay minerals in the long term. Second, poor resistance to acids and alkalis also limits their application. In oilfield development, acidizing and fracturing are common production-enhancing measures, but many clay stabilizers easily fail in acidic or alkaline environments, failing to exert their intended stabilizing effect. Furthermore, poor resistance to water erosion is another problem with current clay stabilizers. During oilfield development, working fluids are often subjected to water erosion; if the clay stabilizer cannot resist this erosion, it will lose its stabilizing effect on clay minerals. Finally, high cost is also a factor limiting the further application of clay stabilizers. The high cost of preparing many clay stabilizers restricts their use in oilfield development. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide an amphoteric clay stabilizer, its preparation method and application, wherein the preparation method enhances the effect of the clay stabilizer and the clay stabilizer can function in complex environments.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing an amphoteric clay stabilizer, comprising the following steps:

[0008] Acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, dimethyldiallylammonium chloride, KH570 modified nano-SiO2 and water were added to a reaction vessel, and nitrogen gas was introduced; after heating, ammonium persulfate and sodium bisulfite were added, followed by the reaction and the addition of polyvinyl alcohol. After polymerization, the mixture was allowed to cool naturally to room temperature to obtain the clay stabilizer.

[0009] Preferably, the mass ratio of acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid and dimethyldiallylammonium chloride is (6~8):(1~2):(1~1.6).

[0010] Preferably, the mass of the KH570 modified nano-SiO2 is 0.2% to 0.5% of the total mass of the clay stabilizer.

[0011] Preferably, the mass of the polyvinyl alcohol is 2% to 4% of the total mass of the clay stabilizer.

[0012] Preferably, the mass of the ammonium persulfate is 1% to 3% of the total mass of acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, dimethyldiallylammonium chloride, and KH570 modified nano-SiO2.

[0013] Preferably, the mass ratio of ammonium persulfate to sodium bisulfite is 1:(0.5~1.5).

[0014] Preferably, the heating condition is heating to 35~50°C.

[0015] Preferably, the reaction time is 1-5 hours; the polymerization time is 4-6 hours.

[0016] Secondly, the present invention provides an amphoteric clay stabilizer.

[0017] Thirdly, the present invention provides an application of an amphoteric clay stabilizer in the field of oil extraction technology.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention synthesizes an amphoteric clay stabilizer by copolymerizing acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, dimethyldiallylammonium chloride, and KH570 modified nano-SiO2. The cationic groups in the polymer can interact with the negative charge on the clay surface, adsorbing onto the clay surface through electrostatic force and reducing the osmotic pressure difference between the inside and outside of the clay surface. At the same time, it forms a protective film on the clay surface, inhibiting clay hydration, swelling, dispersion, and migration. The KH570 modified nano-SiO2 has a similar structure to clay and can fill clay pores, which makes the interaction between the clay stabilizer and the clay more robust, more resistant to erosion, and longer-lasting. Attached Figure Description

[0020] Figure 1 This is an infrared analysis test image of the clay stabilizer prepared in Example 1 of the present invention;

[0021] Figure 2 The anti-swelling rate of the clay stabilizer prepared in Example 1 of this invention at different concentrations;

[0022] Figure 3 This is a water wash resistance test of the clay stabilizer prepared in Example 1 of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0025] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings:

[0028] In a first aspect, the present invention provides a method for preparing an amphoteric clay stabilizer, specifically comprising the following steps:

[0029] Acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, dimethyldiallylammonium chloride, KH570 modified nano-SiO2, and water were added to a reactor, and nitrogen gas was introduced. After heating at 35-50°C, ammonium persulfate and sodium bisulfite were added. The reaction was carried out for 1-5 hours, followed by the addition of polyvinyl alcohol. Polymerization was then carried out for 4-6 hours, followed by natural cooling to room temperature to obtain the clay stabilizer. Acrylamide contains unsaturated double bonds, making it readily capable of free radical polymerization with other monomers. Its polymer segments possess good hydrophilicity and flexibility, which helps form a continuous and dense protective film on the clay surface, enhancing the encapsulation and fixation of clay particles. The sulfonic acid groups in 2-methyl-2-acrylamidopropanesulfonic acid carry a strong negative charge, enabling them to bind to cation sites (such as sodium and calcium ions) on the clay surface through electrostatic interactions, thereby enhancing the polymer's adsorption capacity on the clay surface. Meanwhile, the sulfonic acid groups also improve the polymer's water solubility, helping to form a uniform and stable solution. The quaternary ammonium salt groups in dimethyl diallyl ammonium chloride carry a positive charge, which can generate a strong electrostatic attraction with the negative charge on the clay surface, making it easier for the polymer to adsorb onto the clay surface. This electrostatic adsorption not only enhances the polymer's stability but also promotes its uniform distribution on the clay surface. Nano-SiO2 has a high specific surface area and excellent filling performance, capable of filling the pores between clay particles and reducing the relative movement between them. KH570, as a coupling agent, improves the compatibility between nano-SiO2 and the polymer matrix, allowing nano-SiO2 to be uniformly dispersed in the polymer. KH570-modified nano-SiO2 not only improves the polymer's mechanical strength but also enhances the interfacial bonding force between the polymer and clay particles, making the clay stabilizer more resistant to erosion and with a longer-lasting effect. Ammonium persulfate is a commonly used free radical polymerization initiator. Under heating conditions, it can decompose to produce sulfate free radicals (SO42-). - These free radicals are highly reactive and can initiate free radical polymerization of unsaturated double bonds in monomers. Sodium bisulfite is used as a reducing agent or regulator for ammonium persulfate. It can control the polymerization rate and temperature sensitivity by reacting with ammonium persulfate to regulate the decomposition rate of the initiator and the concentration of free radicals. Furthermore, sodium bisulfite can reduce side reactions, improve polymerization efficiency, and enhance product quality. Polyvinyl alcohol (PVA) is a high-molecular-weight compound with good water solubility and film-forming properties. PVA can further increase the viscosity of the polymer, allowing the clay stabilizer to form a thicker, denser protective film on the clay surface.

[0030] The reactor is equipped with a condenser, a thermometer, a dropping funnel, and a nitrogen pipe. The thermometer is used to measure the temperature during heating, and the nitrogen pipe is used to introduce nitrogen gas to remove dissolved oxygen. The mass ratio of acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, and dimethyldiallyl ammonium chloride is (7~8):(1~2):(1~1.6). The mass of KH570 modified nano-SiO2 is 0.2%~0.5% of the total mass of the clay stabilizer. The mass of polyvinyl alcohol is 2%~4% of the total mass of the clay stabilizer. The mass of ammonium persulfate is 1%~3% of the sum of the masses of acrylamide, dimethyldiallyl ammonium chloride, 2-methyl-2-acrylamidopropanesulfonic acid, and KH570 modified nano-SiO2. The mass ratio of ammonium persulfate to sodium bisulfite is 1:(0.5~1.5).

[0031] Secondly, the present invention provides an amphoteric clay stabilizer prepared by the above-mentioned preparation method. The clay stabilizer prepared by the method of the present invention has excellent temperature resistance, salt resistance, acid and alkali resistance and erosion resistance, and has a long action time. It also has the advantages of low dosage and good anti-swelling effect.

[0032] Thirdly, the present invention provides an application of an amphoteric clay stabilizer in the field of oil extraction technology, wherein the clay stabilizer is used to stabilize clay, inhibit clay hydration and swelling, and facilitate dispersion and migration.

[0033] Example 1

[0034] The preparation process of the supported desulfurizer in this embodiment is as follows:

[0035] In a four-necked flask equipped with a condenser, thermometer, dropping funnel, and nitrogen tube, 7.3 g of acrylamide, 1.1 g of 2-methyl-2-acrylamidopropanesulfonic acid, 1.5 g of dimethyldiallyl ammonium chloride, 0.2 g of KH570 modified nano-SiO2, and 87.5 g of distilled water were added. Nitrogen gas was purged to remove dissolved oxygen. Then, under nitrogen protection, the mixture was heated to 50°C, and 0.26 g of ammonium persulfate (oxidant) and 0.14 g of sodium bisulfite (reducing agent) were added dropwise. After reacting for 1 hour, 2 g of polyvinyl alcohol was added, and polymerization was continued for 4 hours. The reaction was then stopped, and the mixture was allowed to cool naturally to room temperature before being discharged to obtain the clay stabilizer. The infrared spectrum of the clay stabilizer is shown below. Figure 1 As shown. From Figure 1 It can be seen that 3369 cm -1 The absorption peak at 2939 cm⁻¹ is due to the stretching vibration of the N-H group of the amide group. -1 The absorption peak is a characteristic peak of the CH2 stretching vibration. 1641 cm⁻¹ -1 The absorption peak is the stretching vibration peak of C=O. 1349 cm⁻¹ -1 The absorption peak is due to the bending vibration of the CH bond. 1186 cm⁻¹ -1The absorption peak is a symmetric vibrational absorption peak of -SO3. 1120 cm⁻¹ -1 The absorption peak may be due to the CN stretching vibration and the Si-O-Si antisymmetric stretching vibration. (1039 cm⁻¹) -1 The absorption peak is the asymmetric vibrational absorption peak of -SO3. 788 cm⁻¹ -1 The absorption peak may be due to the Si-O-Si symmetric stretching vibration absorption peak. 3430 cm⁻¹ -1 The absorption peak corresponds to the OH stretching vibration of the OH group. Infrared spectroscopy functional group analysis indicates that the product was successfully prepared.

[0036] The anti-swelling rate of clay stabilizers at different concentrations was measured at room temperature, and the results are as follows: Figure 2 As shown in the figure. At a concentration of 2%, the clay stabilizer achieved an anti-swelling rate of 91.53%, indicating that the synthesized clay stabilizer has a good anti-swelling effect. The experimental results of the water wash resistance of the clay stabilizer are shown in the figure. Figure 3 As shown, from Figure 3 It is evident that when the clay stabilizer concentration is above 1.0%, the anti-swelling rate after three washes is higher than 80%. The anti-swelling rate of sodium bentonite treated with the clay stabilizer shows a relatively low decrease after one and two washes, generally within 4%. After three washes, the anti-swelling rate remains within 6%, indicating a small overall decrease and suggesting that the clay stabilizer has good water-washing resistance.

[0037] Example 2

[0038] The preparation process of the supported desulfurizer in this embodiment is as follows:

[0039] In a four-necked flask equipped with a condenser, thermometer, dropping funnel, and nitrogen tube, 6.6 g of acrylamide, 1.4 g of 2-methyl-2-acrylamidopropanesulfonic acid, 1.1 g of dimethyldiallylammonium chloride, 0.3 g of KH570 modified nano-SiO2, and 87.15 g of distilled water were added. Nitrogen gas was purged to remove dissolved oxygen. Then, under nitrogen protection, the mixture was heated to 45 °C, and 0.2 g of ammonium persulfate (oxidant) and 0.25 g of sodium bisulfite (reducing agent) were added dropwise. After reacting for 1 hour, 3 g of polyvinyl alcohol was added, and polymerization was carried out for 5 hours. The reaction was then stopped, and the mixture was allowed to cool naturally to room temperature before being discharged to obtain the clay stabilizer.

[0040] At room temperature, the 2% concentration of clay stabilizer can achieve an anti-swelling rate of 89.83%, indicating that the synthesized clay stabilizer has a good anti-swelling effect.

[0041] Example 3

[0042] The preparation process of the supported desulfurizer in this embodiment is as follows:

[0043] In a four-necked flask equipped with a condenser, thermometer, dropping funnel, and nitrogen tube, 7.6 g of acrylamide, 1.6 g of 2-methyl-2-acrylamidopropanesulfonic acid, 1.3 g of dimethyldiallylammonium chloride, 0.4 g of KH570 modified nano-SiO2, and 84.35 g of distilled water were added. Nitrogen gas was purged to remove dissolved oxygen. Then, under nitrogen protection, the mixture was heated to 40 °C, and 0.3 g of ammonium persulfate (oxidant) and 0.45 g of sodium bisulfite (reducing agent) were added dropwise. After reacting for 1 hour, 4 g of polyvinyl alcohol was added, and polymerization was continued for 6 hours. The reaction was then stopped, and the mixture was allowed to cool naturally to room temperature before being discharged to obtain the clay stabilizer.

[0044] At room temperature, the 2% concentration of clay stabilizer can achieve a swelling prevention rate of 90.26%, indicating that the synthesized clay stabilizer has a good swelling prevention effect.

[0045] Example 4

[0046] The preparation process of the supported desulfurizer in this embodiment is as follows:

[0047] In a four-necked flask equipped with a condenser, thermometer, dropping funnel, and nitrogen tube, 8.0 g of acrylamide, 1.8 g of 2-methyl-2-acrylamidopropanesulfonic acid, 1.6 g of dimethyldiallylammonium chloride, 0.5 g of KH570 modified nano-SiO2, and 84.7 g of distilled water were added. Nitrogen gas was then introduced to remove dissolved oxygen. Under nitrogen protection, the mixture was heated to 35 °C, and 0.2 g of ammonium persulfate (oxidant) and 0.2 g of sodium bisulfite (reducing agent) were added dropwise. After reacting for 1 hour, 3 g of polyvinyl alcohol was added, and polymerization was continued for 5 hours. The reaction was then stopped, and the mixture was allowed to cool naturally to room temperature before being discharged to obtain the clay stabilizer.

[0048] At room temperature, the anti-swelling rate of a 2% concentration of clay stabilizer can reach 91.02%, indicating that the synthesized clay stabilizer has a good anti-swelling effect.

[0049] Example 5

[0050] The preparation process of the supported desulfurizer in this embodiment is as follows:

[0051] In a four-necked flask equipped with a condenser, thermometer, dropping funnel, and nitrogen tube, 6.0 g of acrylamide, 2 g of 2-methyl-2-acrylamidopropanesulfonic acid, 1.5 g of dimethyldiallylammonium chloride, 0.5 g of KH570 modified nano-SiO2, and 86.8 g of distilled water were added. Nitrogen gas was purged to remove dissolved oxygen. Then, under nitrogen protection, the mixture was heated to 35 °C, and 0.1 g of ammonium persulfate (oxidant) and 0.1 g of sodium bisulfite (reducing agent) were added dropwise. After reacting for 3 h, 3 g of polyvinyl alcohol was added, and polymerization was carried out for 4 h. The reaction was then stopped, and the mixture was allowed to cool naturally to room temperature before being discharged to obtain the clay stabilizer.

[0052] Example 6

[0053] The preparation process of the supported desulfurizer in this embodiment is as follows:

[0054] In a four-necked flask equipped with a condenser, thermometer, dropping funnel, and nitrogen tube, 7.6 g of acrylamide, 1 g of 2-methyl-2-acrylamidopropanesulfonic acid, 1 g of dimethyldiallyl ammonium chloride, 0.4 g of KH570 modified nano-SiO2, and 87.7 g of distilled water were added. Nitrogen gas was purged to remove dissolved oxygen. Then, under nitrogen protection, the mixture was heated to 35 °C, and 0.2 g of ammonium persulfate (oxidant) and 0.1 g of sodium bisulfite (reducing agent) were added dropwise. After reacting for 5 h, 2 g of polyvinyl alcohol was added, and polymerization was continued for 6 h. The reaction was then stopped, and the mixture was allowed to cool naturally to room temperature before being discharged to obtain the clay stabilizer.

[0055] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing an amphoteric clay stabilizer, characterized in that, Includes the following steps: Acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, dimethyldiallylammonium chloride, KH570 modified nano-SiO2 and water were added to a reaction vessel, and nitrogen gas was introduced; after heating, ammonium persulfate and sodium bisulfite were added, followed by reaction and then polyvinyl alcohol was added. After polymerization, the mixture was allowed to cool naturally to room temperature to obtain the clay stabilizer. The mass ratio of acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, and dimethyldiallylammonium chloride is (6~8):(1~2):(1~1.6). The mass of the KH570 modified nano-SiO2 is 0.2% to 0.5% of the total mass of the clay stabilizer; The mass of the polyvinyl alcohol is 2% to 4% of the total mass of the clay stabilizer.

2. The method for preparing an amphoteric clay stabilizer according to claim 1, characterized in that, The mass of the ammonium persulfate is 1% to 3% of the total mass of acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, dimethyldiallylammonium chloride, and KH570 modified nano-SiO2.

3. The method for preparing an amphoteric clay stabilizer according to claim 1, characterized in that, The mass ratio of ammonium persulfate to sodium bisulfite is 1:(0.5~1.5).

4. The method for preparing an amphoteric clay stabilizer according to claim 1, characterized in that, The heating conditions are to heat to 35~50℃.

5. The method for preparing an amphoteric clay stabilizer according to claim 1, characterized in that, The reaction time is 1-5 hours; the polymerization time is 4-6 hours.

6. An amphoteric clay stabilizer, characterized in that, The clay stabilizer is prepared by the preparation method according to any one of claims 1-5.

7. The application of the amphoteric clay stabilizer according to claim 6, characterized in that, The application of the clay stabilizer in the field of oil extraction technology.

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