Clay stabilizers and methods for making the same

Abstract

The application belongs to the technical field of clay stabilizer preparation, and particularly relates to a clay stabilizer and a preparation method thereof. The clay stabilizer is composed of the following raw materials: 1-ethyl-3-vinylimidazolium bromide, [3-(dodecyloxy)-2-hydroxypropyl] di(2-hydroxyethyl) methylammonium methyl sulfate, 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium} propane-1-sulfonate, polyallylamine hydrochloride, glycerophosphorylcholine, lauryl alcohol polyoxyethylene polyoxypropylene ether, glacial acetic acid, and the balance is deionized water. The clay stabilizer has excellent permeability and anti-swelling rate due to the synergistic effect between the raw materials.

Description

Technical Field

[0001] This invention belongs to the field of clay stabilizer preparation technology, specifically relating to a clay stabilizer and its preparation method. Background Technology

[0002] Oil and gas field reservoirs all contain a certain amount of clay minerals (such as kaolinite, montmorillonite, illite, chlorite, and illite-montmorillonite mixed layers). During water-based fracturing of the reservoir, these clays will expand and migrate. During expansion, the clay draws water into its crystal structure, leading to an increase in clay volume and thus clogging formation pores. During migration, the clay material is dispersed by external fluids or carried by produced fluids, forming bridging or throttling points at the pore throats of capillaries, resulting in a decrease in formation permeability. To reduce the hydration and swelling of clay minerals, clay stabilizers must be added.

[0003] With the development of oil fields, the application of clay stabilizers has become increasingly widespread, and the types have also increased. Based on their chemical composition, clay stabilizers are mainly divided into four categories: The first category is inorganic salts and inorganic alkalis. The advantages of this type of stabilizer are its low price and simple application method. The disadvantages are its short anti-swelling effective period and poor effect on inhibiting particle migration. The second category is inorganic polymers. The advantages of this type of stabilizer are its low price and longer effective period than ordinary inorganic salts. However, it is still unsuitable for carbonate rock formations and can only be used under weakly acidic conditions, thus greatly limiting its application range. The third category is cationic surfactants. The advantages of this type of stabilizer are its strong adsorption effect and resistance to water flushing. However, it still has the disadvantage of causing the formation to become oleophilic, thus reducing the permeability of the oil and gas phases. The fourth category is organic cationic polymers. The advantages of this type of stabilizer are its wide range of applications, good stabilizing effect, long effective time, and strong resistance to acid, alkali, oil, and water flushing. However, its high-temperature resistance is poor, and its effect will decrease significantly at high temperatures. The above four types of clay stabilizers are all based on physical adsorption mechanisms and do not form chemical bonds with the clay surface. They are prone to desorption under long-term scouring by formation water or high-temperature conditions.

[0004] Patent CN 106147739A discloses a clay stabilizer for fracturing, which, by weight, consists of the following raw materials: 35-50 parts choline chloride, 3-8 parts calcium chloride, 40-50 parts water, 5-10 parts methanol, and 1-5 parts alcohol ether solvent. The choline chloride is a small-molecule quaternary ammonium salt, which only forms a weak electrostatic adsorption with the clay, without a long-chain hydrophobic barrier or chemical cross-linking.

[0005] In conclusion, it is necessary to explore a new type of clay stabilizer. Summary of the Invention

[0006] The purpose of this invention is to provide a clay stabilizer with excellent anti-swelling rate. In addition, this invention also provides a method for its preparation.

[0007] The clay stabilizer of this invention, by mass percentage, is composed of the following raw materials: 14-16% 1-ethyl-3-vinylimidazolium bromide, 23-25% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate, 11-13% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 7-9% polyacrylamide hydrochloride, 7-9% glyceryl phosphorylcholine, 9-11% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.15-0.17% glacial acetic acid, and the balance being deionized water.

[0008] The CAS number for [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt is 18602-17-0.

[0009] The CAS number for 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate is 151778-80-2.

[0010] The weight-average molecular weight of polyacrylamide hydrochloride is 15,000.

[0011] The method for preparing the clay stabilizer according to the present invention comprises the following steps:

[0012] (1) Add deionized water to the reaction vessel, heat to 40-45℃ with stirring, add glacial acetic acid, then add polyacrylamine hydrochloride and stir to dissolve, then add [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt and stir to dissolve, cool to 25-30℃ and then add 1-ethyl-3-vinylimidazolium bromide, glyceryl phosphorylcholine and lauryl alcohol polyoxyethylene polyoxypropylene ether and stir until uniform;

[0013] (2) Add 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate to the mixture obtained in step (1) and stir until homogeneous;

[0014] (3) The system prepared in step (2) is sheared to prepare a clay stabilizer.

[0015] Wherein: the stirring speed in step (1) is 250 r / min.

[0016] In step (1), polyacrylamide hydrochloride is added and stirred to dissolve for 20-25 minutes. Then, [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt is added and stirred to dissolve for 15-20 minutes. After cooling to 25-30℃, 1-ethyl-3-vinylimidazolium bromide is added and stirred for 6-8 minutes. Then, glycerol phosphorylcholine is added and stirred for 6-8 minutes. Finally, lauryl alcohol polyoxyethylene polyoxypropylene ether is added and stirred for 6-8 minutes.

[0017] In step (2), add 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate and stir for 13-15 min. During this process, the stirring temperature is 20-25℃ and the stirring speed is 250 r / min.

[0018] In step (3), the shearing speed is 1000 r / min, the shearing time is 10-12 min, and the shearing temperature is 30-35℃.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The clay stabilizer of the present invention, the imidazolium cation in 1-ethyl-3-vinylimidazolium bromide spontaneously adsorbs onto the negatively charged clay surface through electrostatic attraction, and embeds itself into the clay interlayer through cation exchange reaction, reducing the interlayer spacing, competing with water molecules, and preventing water molecules from entering the clay crystal layer. The ethyl chain length allows it to achieve rapid penetration. The quaternary ammonium salt cation in the molecular structure of [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt undergoes strong electrostatic adsorption with the negatively charged clay surface, neutralizing the charge. The long-chain alkyl in the molecular structure can form a hydrophobic barrier, preventing water molecules from entering the clay interlayer. Its polyhydroxy structure enhances the hydrogen bonding with the clay, improving adsorption stability. Its molecular weight is moderate, which can effectively adsorb without causing blockage of low-permeability reservoirs. The zwitterionic properties of 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate give it excellent diffusion efficiency in porous media. The silyl group hydrolyzes to form silanol, which condenses with Al-OH groups on the clay surface at downhole temperatures to form stable Si-O-Al covalent bonds, resulting in stronger adsorption. The sulfonate anion provides charge buffering, balancing the charge distribution of the system and enhancing its compatibility. Polyacrylamide hydrochloride forms a dense protective film on the clay particle surface through multi-point adsorption and physical entanglement, encapsulating the clay particles and preventing contact with water. Its high charge density can generate a charge synergistic effect with other cationic components in the system, enhancing the overall adsorption strength. Simultaneously, its amino groups can form multi-point hydrogen bonds with the clay surface for anchoring, improving erosion resistance. Therefore, the prepared clay stabilizer exhibits excellent anti-swelling rate.

[0021] (2) The clay stabilizer of the present invention further includes glycerol phosphorylcholine and lauryl alcohol polyoxyethylene polyoxypropylene ether. The phosphate ester groups of glycerol phosphorylcholine interact with the Al sites on the clay surface through hydrogen bonding and electrostatic interaction, and the quaternary ammonium head of the choline faces outward to reduce the local zeta potential. The addition of lauryl alcohol polyoxyethylene polyoxypropylene ether can reduce interfacial tension and improve the permeability of the prepared clay stabilizer in low-permeability reservoirs.

[0022] (3) The purpose of adding acetic acid to the clay stabilizer system described in this invention is to control the system to be weakly acidic, so that 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate can generate silanol intermediates at a controllable rate during ground storage and injection, avoiding extremely slow hydrolysis under neutral conditions or rapid precipitation under alkaline conditions, and inhibiting premature condensation crosslinking, ensuring that silanol can efficiently condense with Al-OH groups on the clay surface under downhole temperature conditions to form stable Si-O-Al covalent bonds, thereby achieving chemical anchoring; the unreacted silanol can further self-condense to form a Si-O-Si network, enhancing the mechanical strength and erosion resistance of the overall protective layer.

[0023] (4) The method for preparing the clay stabilizer described in this invention is simple, easy to implement, and the prepared clay stabilizer has stable performance. Detailed Implementation

[0024] Example 1

[0025] The clay stabilizer described in Example 1 is composed of the following raw materials by mass percentage: 15% 1-ethyl-3-vinylimidazolium bromide, 24% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt, 12% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 8% polyacrylamide hydrochloride, 8% glyceryl phosphorylcholine, 10% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.16% glacial acetic acid, and the balance being deionized water.

[0026] The CAS number for [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt is 18602-17-0.

[0027] The CAS number for 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate is 151778-80-2.

[0028] The weight-average molecular weight of polyacrylamide hydrochloride is 15,000.

[0029] The method for preparing the clay stabilizer described in Example 1 consists of the following steps:

[0030] (1) Add deionized water to the reaction vessel, heat to 43°C with stirring, add glacial acetic acid, then add polyacrylamine hydrochloride and stir to dissolve, then add [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt and stir to dissolve, cool to 28°C and then add 1-ethyl-3-vinylimidazolium bromide, glyceryl phosphorylcholine and lauryl alcohol polyoxyethylene polyoxypropylene ether and stir until uniform;

[0031] (2) Add 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate to the mixture obtained in step (1) and stir until homogeneous;

[0032] (3) The system prepared in step (2) is sheared to prepare a clay stabilizer.

[0033] Wherein: the stirring speed in step (1) is 250 r / min.

[0034] In step (1), polyacrylamide hydrochloride was added and stirred for 23 min to dissolve. Then, [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt was added and stirred for 17 min to dissolve. After cooling to 28°C, 1-ethyl-3-vinylimidazolium bromide was added and stirred for 7 min. Then, glycerol phosphorylcholine was added and stirred for 7 min. Finally, lauryl alcohol polyoxyethylene polyoxypropylene ether was added and stirred for 7 min.

[0035] In step (2), 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate is added and stirred for 14 min. During this process, the stirring temperature is 23℃ and the stirring speed is 250 r / min.

[0036] In step (3), the shearing speed is 1000 r / min, the shearing time is 11 min, and the shearing temperature is 33℃.

[0037] According to the "SY / T 5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the clay stabilizer prepared in Example 1 was formulated into a 2.0% mass fraction aqueous solution, mixed with sodium-based bentonite, and then kept at a constant temperature of 25℃ for 2 hours or at a constant temperature of 60℃ for 4 hours (simulating the downhole temperature environment). After centrifugation, the anti-swelling rate was calculated. The anti-swelling rate after being kept at a constant temperature of 25℃ for 2 hours was 88.5%, and the anti-swelling rate after being kept at a constant temperature of 60℃ for 4 hours was 97.8%.

[0038] According to section 7.4 of the "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" (SY / T 5971-2016), the water wash resistance was tested. After standing at room temperature for 2 hours, the retention rate after 3 water washes was 85.2%. After standing at 60℃ for 4 hours, the retention rate after 3 water washes was 93.6%.

[0039] Data on anti-swelling rate and water washing retention rate show that the data obtained by standing at a constant temperature of 60℃ for 4 hours is better than that obtained by standing at room temperature for 2 hours. This is because the silane component undergoes hydrolysis-condensation crosslinking under the downhole temperature environment, forming more stable Si-O-Al chemical bonds, thereby significantly improving the stability of the clay.

[0040] Example 2

[0041] The clay stabilizer described in Example 2 is composed of the following raw materials by mass percentage: 14% 1-ethyl-3-vinylimidazolium bromide, 23% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt, 13% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 7% polyacrylamide hydrochloride, 9% glyceryl phosphorylcholine, 11% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.15% glacial acetic acid, and the balance being deionized water.

[0042] The CAS number for [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt is 18602-17-0.

[0043] The CAS number for 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate is 151778-80-2.

[0044] The weight-average molecular weight of polyacrylamide hydrochloride is 15,000.

[0045] The method for preparing the clay stabilizer described in Example 2 consists of the following steps:

[0046] (1) Add deionized water to the reaction vessel, heat to 40°C with stirring, add glacial acetic acid, then add polyacrylamine hydrochloride and stir to dissolve, then add [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt and stir to dissolve, cool to 25°C and then add 1-ethyl-3-vinylimidazolium bromide, glyceryl phosphorylcholine and lauryl alcohol polyoxyethylene polyoxypropylene ether and stir until uniform;

[0047] (2) Add 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate to the mixture obtained in step (1) and stir until homogeneous;

[0048] (3) The system prepared in step (2) is sheared to prepare a clay stabilizer.

[0049] Wherein: the stirring speed in step (1) is 250 r / min.

[0050] In step (1), polyacrylamide hydrochloride was added and stirred for 20 min to dissolve. Then, [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt was added and stirred for 17 min to dissolve. After cooling to 25°C, 1-ethyl-3-vinylimidazolium bromide was added and stirred for 6 min. Then, glycerol phosphorylcholine was added and stirred for 8 min. Finally, lauryl alcohol polyoxyethylene polyoxypropylene ether was added and stirred for 8 min.

[0051] In step (2), 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate is added and stirred for 15 min. During this process, the stirring temperature is 20℃ and the stirring speed is 250 r / min.

[0052] In step (3), the shearing speed is 1000 r / min, the shearing time is 10 min, and the shearing temperature is 30℃.

[0053] According to the "SY / T 5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the clay stabilizer prepared in Example 2 was formulated into a 2.0% mass fraction aqueous solution, mixed with sodium-based bentonite, and then kept at a constant temperature of 25°C for 2 hours or at a constant temperature of 60°C for 4 hours. After centrifugation, the anti-swelling rate was calculated. The anti-swelling rate after being kept at a constant temperature of 25°C for 2 hours was 86.2%, and the anti-swelling rate after being kept at a constant temperature of 60°C for 4 hours was 95.5%.

[0054] According to section 7.4 of the "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" (SY / T 5971-2016), the water wash resistance was tested. After standing at room temperature for 2 hours, the retention rate after 3 water washes was 83.7%. After standing at 60℃ for 4 hours, the retention rate after 3 water washes was 91.8%.

[0055] Example 3

[0056] The clay stabilizer described in Example 3 is composed of the following raw materials by mass percentage: 16% 1-ethyl-3-vinylimidazolium bromide, 25% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt, 11% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 9% polyacrylamide hydrochloride, 7% glyceryl phosphorylcholine, 9% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.17% glacial acetic acid, and the balance being deionized water.

[0057] The CAS number for [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt is 18602-17-0.

[0058] The CAS number for 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate is 151778-80-2.

[0059] The weight-average molecular weight of polyacrylamide hydrochloride is 15,000.

[0060] The method for preparing the clay stabilizer described in Example 3 consists of the following steps:

[0061] (1) Add deionized water to the reaction vessel, heat to 45°C with stirring, add glacial acetic acid, then add polyacrylamine hydrochloride and stir to dissolve, then add [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt and stir to dissolve, cool to 30°C and then add 1-ethyl-3-vinylimidazolium bromide, glyceryl phosphorylcholine and lauryl alcohol polyoxyethylene polyoxypropylene ether and stir until uniform;

[0062] (2) Add 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate to the mixture obtained in step (1) and stir until homogeneous;

[0063] (3) The system prepared in step (2) is sheared to prepare a clay stabilizer.

[0064] Wherein: the stirring speed in step (1) is 250 r / min.

[0065] In step (1), polyacrylamide hydrochloride was added and stirred to dissolve for 25 min. Then, [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt was added and stirred to dissolve for 20 min. After cooling to 30℃, 1-ethyl-3-vinylimidazolium bromide was added and stirred for 8 min. Then, glycerol phosphorylcholine was added and stirred for 6 min. Finally, lauryl alcohol polyoxyethylene polyoxypropylene ether was added and stirred for 6 min.

[0066] In step (2), 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate is added and stirred for 13 min. During this process, the stirring temperature is 25℃ and the stirring speed is 250 r / min.

[0067] In step (3), the shearing speed is 1000 r / min, the shearing time is 12 min, and the shearing temperature is 35℃.

[0068] According to the "SY / T 5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the clay stabilizer prepared in Example 3 was formulated into a 2.0% (w / w) aqueous solution, mixed with sodium-based bentonite, and then kept at a constant temperature of 25°C for 2 hours or at a constant temperature of 60°C for 4 hours. After centrifugation, the anti-swelling rate was calculated. The anti-swelling rate after being kept at a constant temperature of 25°C for 2 hours was 87.8%, and the anti-swelling rate after being kept at a constant temperature of 60°C for 4 hours was 96.2%.

[0069] According to section 7.4 of the "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" (SY / T 5971-2016), the water wash resistance was tested. After standing at room temperature for 2 hours, the water wash retention rate was 84.5%. After standing at 60℃ for 4 hours, the water wash retention rate was 92.5%.

[0070] Comparative Example 1

[0071] The preparation method of the clay stabilizer described in Comparative Example 1 is the same as that in Example 1, the only difference being the composition of the raw materials. The clay stabilizer described in Comparative Example 1, by mass percentage, consists of the following raw materials: 24% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate, 12% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 8% polyacrylamide hydrochloride, 8% glyceryl phosphorylcholine, 10% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.16% glacial acetic acid, and the balance being deionized water.

[0072] According to the "SY / T 5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the clay stabilizer prepared in Comparative Example 1 was formulated into a 2.0% (w / w) aqueous solution, mixed with sodium-based bentonite, and then kept at a constant temperature of 25℃ for 2 hours or at a constant temperature of 60℃ for 4 hours. After centrifugation, the anti-swelling rate was calculated. The anti-swelling rate after being kept at a constant temperature of 25℃ for 2 hours was 78.2%, and the anti-swelling rate after being kept at a constant temperature of 60℃ for 4 hours was 84.5%.

[0073] According to section 7.4 of the "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" (SY / T 5971-2016), the water wash resistance was tested. After standing at room temperature for 2 hours, the retention rate after 3 water washes was 75.2%. After standing at 60℃ for 4 hours, the retention rate after 3 water washes was 77.9%.

[0074] Comparative Example 2

[0075] The preparation method of the clay stabilizer described in Comparative Example 2 is the same as that in Example 1, the only difference being the composition of the raw materials. The clay stabilizer described in Comparative Example 2, by mass percentage, consists of the following raw materials: 15% 1-ethyl-3-vinylimidazolium bromide, 12% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 8% polyacrylamide hydrochloride, 8% glyceryl phosphorylcholine, 10% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.16% glacial acetic acid, and the balance being deionized water.

[0076] According to the "SY / T 5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the clay stabilizer prepared in Comparative Example 2 was formulated into a 2.0% mass fraction aqueous solution, mixed with sodium-based bentonite, and then kept at a constant temperature of 25℃ for 2 hours or at a constant temperature of 60℃ for 4 hours. After centrifugation, the anti-swelling rate was calculated. The anti-swelling rate after being kept at a constant temperature of 25℃ for 2 hours was 75.6%, and the anti-swelling rate after being kept at a constant temperature of 60℃ for 4 hours was 78.5%.

[0077] According to section 7.4 of the "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" (SY / T 5971-2016), the water wash resistance was tested. After standing at room temperature for 2 hours, the retention rate after 3 water washes was 68.5%. After standing at 60℃ for 4 hours, the retention rate after 3 water washes was 71.5%.

[0078] Comparative Example 3

[0079] The preparation method of the clay stabilizer described in Comparative Example 3 is the same as that in Example 1, the only difference being the composition of the raw materials. The clay stabilizer described in Comparative Example 3, by mass percentage, consists of the following raw materials: 15% 1-ethyl-3-vinylimidazolium bromide, 24% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt, 8% polyacrylamide hydrochloride, 8% glyceryl phosphorylcholine, 10% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.16% glacial acetic acid, and the balance being deionized water.

[0080] According to the "SY / T 5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the clay stabilizer prepared in Comparative Example 3 was formulated into a 2.0% (w / w) aqueous solution, mixed with sodium-based bentonite, and then kept at a constant temperature of 25℃ for 2 hours or at a constant temperature of 60℃ for 4 hours. After centrifugation, the anti-swelling rate was calculated. The anti-swelling rate after being kept at a constant temperature of 25℃ for 2 hours was 76.8%, and the anti-swelling rate after being kept at a constant temperature of 60℃ for 4 hours was 82.3%.

[0081] According to section 7.4 of the "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" (SY / T 5971-2016), the water wash resistance was tested. After standing at room temperature for 2 hours, the retention rate after 3 water washes was 74.5%. After standing at 60℃ for 4 hours, the retention rate after 3 water washes was 76.4%.

[0082] Comparative Example 4

[0083] The preparation method of the clay stabilizer described in Comparative Example 4 is the same as that in Example 1, the only difference being the composition of the raw materials. The clay stabilizer described in Comparative Example 4, by mass percentage, consists of the following raw materials: 15% 1-ethyl-3-vinylimidazolium bromide, 24% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt, 12% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 8% glyceryl phosphorylcholine, 10% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.16% glacial acetic acid, and the balance being deionized water.

[0084] According to the "SY / T 5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the clay stabilizer prepared in Comparative Example 4 was formulated into a 2.0% mass fraction aqueous solution, mixed with sodium-based bentonite, and then kept at a constant temperature of 25℃ for 2 hours or at a constant temperature of 60℃ for 4 hours. After centrifugation, the anti-swelling rate was calculated. The anti-swelling rate after being kept at a constant temperature of 25℃ for 2 hours was 82.5%, and the anti-swelling rate after being kept at a constant temperature of 60℃ for 4 hours was 89.6%.

[0085] According to section 7.4 of the "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" (SY / T 5971-2016), the water wash resistance was tested. After standing at room temperature for 2 hours, the water wash retention rate was 76.7%. After standing at 60℃ for 4 hours, the water wash retention rate was 81.1%.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A clay stabilizer, characterized in that: By mass percentage, it is composed of the following raw materials: 14-16% 1-ethyl-3-vinylimidazolium bromide, 23-25% [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate, 11-13% 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate, 7-9% polyacrylamide hydrochloride, 7-9% glyceryl phosphorylcholine, 9-11% lauryl alcohol polyoxyethylene polyoxypropylene ether, 0.15-0.17% glacial acetic acid, and the balance being deionized water.

2. The clay stabilizer according to claim 1, characterized in that: The weight-average molecular weight of polyacrylamide hydrochloride is 15,000.

3. A method for preparing the clay stabilizer according to claim 1, characterized in that: It consists of the following steps: (1) Add deionized water to the reaction vessel, heat to 40-45℃ with stirring, add glacial acetic acid, then add polyacrylamine hydrochloride and stir to dissolve, then add [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt and stir to dissolve, cool to 25-30℃ and then add 1-ethyl-3-vinylimidazolium bromide, glyceryl phosphorylcholine and lauryl alcohol polyoxyethylene polyoxypropylene ether and stir until uniform; (2) Add 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate to the mixture obtained in step (1) and stir until homogeneous; (3) The system prepared in step (2) is sheared to prepare a clay stabilizer.

4. The method for preparing the clay stabilizer according to claim 3, characterized in that: In step (1), the stirring speed is 250 r / min.

5. The method for preparing the clay stabilizer according to claim 3, characterized in that: In step (1), polyacrylamide hydrochloride is added and stirred to dissolve for 20-25 minutes. Then, [3-(dodecyloxy)-2-hydroxypropyl]bis(2-hydroxyethyl)methylammonium sulfate methyl ester salt is added and stirred to dissolve for 15-20 minutes. After cooling to 25-30℃, 1-ethyl-3-vinylimidazolium bromide is added and stirred for 6-8 minutes. Then, glycerol phosphorylcholine is added and stirred for 6-8 minutes. Finally, lauryl alcohol polyoxyethylene polyoxypropylene ether is added and stirred for 6-8 minutes.

6. The method for preparing the clay stabilizer according to claim 3, characterized in that: In step (2), add 3-{(dimethyl(3-trimethoxysilyl)propyl)ammonium}propane-1-sulfonate and stir for 13-15 min. During this process, the stirring temperature is 20-25℃ and the stirring speed is 250 r / min.

7. The method for preparing the clay stabilizer according to claim 3, characterized in that: In step (3), the shearing speed is 1000 r / min, the shearing time is 10-12 min, and the shearing temperature is 30-35℃.