Urea cation homopolymer ionic liquid clay stabilizer and preparation method thereof
By preparing a urea cationic homopolymer ionic liquid clay stabilizer, the problems of complex production process, weak water washing resistance, and poor compatibility with fracturing fluid of existing clay stabilizers have been solved. It achieves multi-point adsorption, strong water washing resistance, and significant effect in preventing clay swelling, and is suitable for fracturing construction in low-permeability reservoirs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NAT PETROLEUM CORP
- Filing Date
- 2024-10-30
- Publication Date
- 2026-05-01
AI Technical Summary
Existing clay stabilizers have complex production processes, weak water washing resistance, and poor compatibility with fracturing fluids, leading to reservoir damage and reduced permeability.
A urea cationic homopolymer ionic liquid clay stabilizer with high charge density was prepared by mixing N,N-dimethylethanolamine with urea, adding allyl chloride and an initiator, and then reacting the mixture.
It achieves multi-point adsorption, strong water washing resistance, good compatibility with fracturing fluid, significantly prevents clay swelling, ensures the sand-carrying capacity of fracturing fluid, and is suitable for low-permeability reservoirs.
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Abstract
Description
Urea cationic homopolymer ionic liquid clay stabilizer and its preparation method Technical Field
[0001] This invention relates to the field of oilfield chemical technology, specifically to a urea cationic homopolymer ionic liquid clay stabilizer and its preparation method. Background Technology
[0002] my country possesses abundant unconventional oil and gas resources, and hydraulic fracturing is its primary reservoir stimulation method. During hydraulic fracturing, a large amount of aqueous solution enters the formation and comes into contact with clay minerals, causing clay hydration, swelling, dispersion, and migration, thereby reducing reservoir permeability or blocking reservoir channels. Therefore, it is essential to use clay stabilizers to improve the anti-swelling properties of the injected fluid, reduce the dispersion and migration of clay minerals, and thus minimize reservoir damage and maintain reservoir permeability.
[0003] Currently, commonly used clay stabilizers mainly include inorganic salts, quaternary ammonium salt surfactants, polyamines, and polyquaternary ammonium salts. While existing clay stabilizers all exhibit good anti-swelling effects, they also have certain drawbacks: inorganic salts cannot form multi-point adsorption, have short effective time, and require large dosages; quaternary ammonium salt surfactants can cause the reservoir to become oil-wetted, thereby reducing oil phase permeability and hindering crude oil extraction; polyamines have complex production processes, poor water washability, and short effective periods; polyquaternary ammonium salts have large molecular weights and are unsuitable for low-permeability reservoirs, exacerbating damage to their permeability; furthermore, the aforementioned types of clay stabilizers have poor compatibility with fracturing fluids, significantly reducing fracturing fluid viscosity, affecting its proppant-carrying capacity, and increasing the difficulty of proppant addition during fracturing operations.
[0004] Therefore, developing a clay stabilizer that is simple to prepare, has significant anti-swelling ability, strong water-washing resistance, and good compatibility with fracturing fluid has become an urgent problem to be solved. Summary of the Invention
[0005] This invention provides a urea cationic homopolymer ionic liquid clay stabilizer and its preparation method, which overcomes the shortcomings of the prior art and can effectively solve the problems of complex production process, poor water washing resistance and poor compatibility with fracturing fluid in existing clay stabilizers.
[0006] One of the technical solutions of the present invention is achieved through the following measures: a urea cationic homopolymer ionic liquid clay stabilizer is prepared according to the following method: First, a required amount of N,N-dimethylethanolamine is mixed with urea, heated and stirred to obtain a suspension; Second, a required amount of allyl chloride is added to the suspension to react and obtain ionic liquid A; Third, a required amount of initiator is added to ionic liquid A to react and obtain the urea cationic homopolymer ionic liquid clay stabilizer.
[0007] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: In the first step above, the molar ratio of urea to N,N-dimethylethanolamine is 1 to 3:1 to 1.2, and the heating temperature is 50°C to 80°C.
[0008] In the second step above, the molar ratio of N,N-dimethylethanolamine to allyl chloride is 1 to 1.2:1, and the reaction time is 2 to 6 hours.
[0009] In the third step above, the initiator is one or more of the following: ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. The amount of initiator used is 0.1% to 1% of the total mass of N,N-dimethylethanolamine and allyl chloride. The reaction temperature is 40°C to 80°C, and the reaction time is 4h to 8h.
[0010] The second technical solution of the present invention is achieved through the following measures: A method for preparing a urea cationic homopolymer ionic liquid clay stabilizer is carried out according to the following steps: First, N,N-dimethylethanolamine and urea are mixed in a required amount, heated and stirred to obtain a suspension; Second, allyl chloride is added to the suspension in a required amount to react and obtain ionic liquid A; Third, an initiator is added to ionic liquid A in a required amount to react and obtain the urea cationic homopolymer ionic liquid clay stabilizer.
[0011] The following is a further optimization and / or improvement of the second technical solution of the invention: In the first step above, the molar ratio of urea to N,N-dimethylethanolamine is 1 to 3:1 to 1.2, and the heating temperature is 50°C to 80°C.
[0012] In the second step above, the molar ratio of N,N-dimethylethanolamine to allyl chloride is 1 to 1.2:1, and allyl chloride is added slowly dropwise for a reaction time of 2 to 6 hours.
[0013] In the third step above, the initiator is one or more of the following: ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. The amount of initiator used is 0.1% to 1% of the total mass of N,N-dimethylethanolamine and allyl chloride. The reaction temperature is 40°C to 80°C, and the reaction time is 4h to 8h.
[0014] This invention provides a urea cationic homopolymer ionic liquid clay stabilizer and its preparation method. The clay stabilizer is a composite of urea and a cationic homopolymer containing repeating cationic and hydroxyl units. The urea cationic homopolymer ionic liquid clay stabilizer is obtained by adding allyl chloride to a suspension of N,N-dimethylethanolamine and urea, followed by an initiator, and continuing the reaction. The resulting urea cationic homopolymer ionic liquid clay stabilizer exhibits high charge density, the ability to form multi-point adsorption, strong water washability, good compatibility with fracturing fluids, and significant effect in preventing clay swelling. Detailed Implementation
[0015] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.
[0016] The present invention will be further described below with reference to the embodiments: Embodiment 1: The urea cationic homopolymer ionic liquid clay stabilizer was prepared according to the following method: First, the required amount of N,N-dimethylethanolamine was mixed with urea, heated and stirred to obtain a suspension; Second, the required amount of allyl chloride was added to the suspension to react and obtain ionic liquid A; Third, the required amount of initiator was added to ionic liquid A to react and obtain urea cationic homopolymer ionic liquid clay stabilizer.
[0017] The urea cationic homopolymer ionic liquid clay stabilizer of this invention is composed of urea and homopolymer containing cations and hydroxyl repeating units. It has high charge density, can form multi-point adsorption, strong water washing resistance, significant anti-swelling effect, good compatibility with fracturing fluid, and has little impact on the viscosity of fracturing fluid.
[0018] Example 2: As an optimization of the above example, in the first step, the molar ratio of urea to N,N-dimethylethanolamine is 1 to 3:1 to 1.2, and the heating temperature is 50°C to 80°C.
[0019] Example 3: As an optimization of the above example, in the second step, the molar ratio of N,N-dimethylethanolamine to allyl chloride is 1 to 1.2:1, and the reaction time is 2 to 6 hours.
[0020] Example 4: As an optimization of the above example, in the third step, the initiator is one or more of ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. The amount of initiator is 0.1% to 1% of the total mass of N,N-dimethylethanolamine and allyl chloride. The reaction temperature is 40°C to 80°C, and the reaction time is 4h to 8h.
[0021] Example 5: The preparation method of the urea cationic homopolymer ionic liquid clay stabilizer is as follows: First, the required amount of N,N-dimethylethanolamine is mixed with urea, heated and stirred to obtain a suspension; Second, the required amount of allyl chloride is added to the suspension to react and obtain ionic liquid A; Third, the required amount of initiator is added to ionic liquid A to react and obtain urea cationic homopolymer ionic liquid clay stabilizer.
[0022] In this invention, the reaction process for preparing the urea cationic homopolymer ionic liquid clay stabilizer is shown in the following formula: In the formula: n is the degree of polymerization of N-allyl-N-(2-hydroxyethyl)-N,N-dimethylammonium chloride monomer, and n is an integer.
[0023] The urea cationic homopolymer ionic liquid clay stabilizer in this invention is prepared by a "one-pot method" using ionic liquid as solvent. It has no obvious vapor pressure, good thermal stability, simple and safe operation, and the reaction product does not require complicated purification operations and can be directly used in reservoir fracturing operations.
[0024] Example 6: According to the present invention, urea cationic homopolymer ionic liquid clay stabilizer sample 1 was prepared by the following method: First, 89.1g of N,N-dimethylethanolamine and 120g of urea were mixed, heated to 55°C, and stirred to obtain a suspension; Second, 76.5g of allyl chloride was slowly added dropwise to the suspension, and the reaction was carried out for 6 hours to obtain ionic liquid A; Third, 0.5g of ammonium persulfate was added to ionic liquid A, the temperature was lowered to 40°C, and the reaction was carried out for 6 hours to obtain urea cationic homopolymer ionic liquid clay stabilizer, denoted as sample 1.
[0025] Example 7: According to the present invention, urea cationic homopolymer ionic liquid clay stabilizer sample 2 was prepared by the following method: First, 90g of N,N-dimethylethanolamine and 120g of urea were mixed, heated to 60°C, and stirred to obtain a suspension; Second, 76.5g of allyl chloride was slowly added dropwise to the suspension, and after the addition was completed, the reaction was carried out for 6h to obtain ionic liquid A; Third, 0.2g of azobisisobutyramidine hydrochloride was added to ionic liquid A, the reaction system temperature was maintained at 60°C, and the reaction was carried out for 6h to obtain urea cationic homopolymer ionic liquid clay stabilizer, denoted as sample 2.
[0026] Example 8: According to the present invention, urea cationic homopolymer ionic liquid clay stabilizer sample 3 was prepared by the following method: First, 98g of N,N-dimethylethanolamine and 150g of urea were mixed, heated to 60°C, and stirred to obtain a suspension; Second, 76.5g of allyl chloride was slowly added dropwise to the suspension, and after the addition was completed, the reaction was carried out for 6 hours to obtain ionic liquid A; Third, 0.5g of benzoyl peroxide was added to ionic liquid A, the temperature was raised to 80°C, and the reaction was carried out for 8 hours to obtain urea cationic homopolymer ionic liquid clay stabilizer, denoted as sample 3.
[0027] Comparative Example 1: Using acetone instead of urea as the solvent, sample 4 was prepared according to the preparation method of Example 7: First, 0.55 mol of N,N-dimethylethanolamine was dissolved in 500 mL of acetone and stirred at room temperature to obtain a mixture; Second, 0.5 mol of allyl chloride was slowly added dropwise to the mixture. After the addition was complete, the temperature was raised to 55 °C and the reaction was continued for 6 h to obtain an N-allyl-N-(2-hydroxyethyl)-N,N-dimethylammonium chloride liquid solution; Third, N-allyl-N-(2-hydroxyethyl)-N,N-dimethylammonium chloride liquid solution was prepared. The N-allyl-N-(2-hydroxyethyl)-N,N-dimethylammonium chloride liquid solution was cooled to room temperature, filtered, washed with acetone, and dried under vacuum to obtain solid N-allyl-N-(2-hydroxyethyl)-N,N-dimethylammonium chloride with a yield of 99.6%. In the fourth step, 0.1 mol of N-allyl-N-(2-hydroxyethyl)-N,N-dimethylammonium chloride was dissolved in 12 g of tap water, heated to 40 °C, and 0.05 g of ammonium persulfate was added. The reaction was continued for 6 h to obtain cationic homopolymer clay stabilizer, which was designated as sample 4.
[0028] Referring to the standard requirements in SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields", the anti-swelling rate, water washing anti-swelling rate and gel viscosity retention rate of the urea cationic homopolymer ionic liquid clay stabilizers obtained in Examples 6 to 8 and the cationic homopolymer clay stabilizer obtained in Comparative Example 1 were tested. The results are shown in Table 1. As can be seen from Table 1, the urea cationic homopolymer ionic liquid clay stabilizer has better anti-swelling (shrinkage swelling) and water washing resistance, indicating that its components have a good synergistic effect and have little impact on the performance of fracturing fluid.
[0029] Therefore, the urea cationic homopolymer ionic liquid clay stabilizer of the present invention has high charge density, strong water washing resistance, and significant effect in preventing clay swelling. Moreover, it has little effect on the base fluid viscosity of fracturing fluid, ensuring the sand-carrying performance of fracturing fluid, and can be used for fracturing construction in low-permeability and ultra-low-permeability reservoirs.
[0030] In summary, the preparation process of this urea cationic homopolymer ionic liquid clay stabilizer is simple, does not use low-boiling-point, toxic or harmful organic solvents, and the reaction process is safe and controllable, making it promising for industrial production.
[0031] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.
Claims
1. A urea cationic homopolymer ionic liquid clay stabilizer, characterized in that... The following method was used to prepare the suspension: First, the required amount of N,N-dimethylethanolamine was mixed with urea, heated and stirred to obtain a suspension; The second step is to add the required amount of allyl chloride to the suspension and react to obtain ionic liquid A; the third step is to add the required amount of initiator to ionic liquid A and react to obtain urea cationic homopolymer ionic liquid clay stabilizer.
2. The urea cationic homopolymer ionic liquid clay stabilizer according to claim 1, characterized in that... In the first step, the molar ratio of urea to N,N-dimethylethanolamine is 1 to 3:1 to 1.2, and the heating temperature is 50°C to 80°C.
3. The urea cationic homopolymer ionic liquid clay stabilizer according to claim 1 or 2, characterized in that... In the second step, the molar ratio of N,N-dimethylethanolamine to allyl chloride is 1 to 1.2:1, and the reaction time is 2 to 6 hours.
4. The urea cationic homopolymer ionic liquid clay stabilizer according to claim 1, 2, or 3, characterized in that... In the third step, the initiator is one or more of the following: ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. The amount of initiator used is 0.1% to 1% of the total mass of N,N-dimethylethanolamine and allyl chloride. The reaction temperature is 40℃ to 80℃, and the reaction time is 4h to 8h.
5. The urea cationic homopolymer ionic liquid clay stabilizer according to claim 1, 2, 3, or 4, characterized in that... In the third step, the initiator is one or more of the following: ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. The amount of initiator used is 0.1% to 1% of the total mass of N,N-dimethylethanolamine and allyl chloride. The reaction temperature is 40℃ to 80℃, and the reaction time is 4h to 8h.
6. A method for preparing a urea cationic homopolymer ionic liquid clay stabilizer, characterized in that... The following steps are performed: First, mix the required amount of N,N-dimethylethanolamine with urea, heat and stir to obtain a suspension; The second step is to add the required amount of allyl chloride to the suspension and react to obtain ionic liquid A; the third step is to add the required amount of initiator to ionic liquid A and react to obtain urea cationic homopolymer ionic liquid clay stabilizer.
7. The method for preparing the urea cationic homopolymer ionic liquid clay stabilizer according to claim 6, characterized in that... In the first step, the molar ratio of urea to N,N-dimethylethanolamine is 1 to 3:1 to 1.2, and the heating temperature is 50°C to 80°C.
8. The method for preparing the urea cationic homopolymer ionic liquid clay stabilizer according to claim 6 or 7, characterized in that... In the second step, the molar ratio of N,N-dimethylethanolamine to allyl chloride is 1 to 1.2:1, and allyl chloride is added slowly dropwise for a reaction time of 2 to 6 hours.
9. The method for preparing the urea cationic homopolymer ionic liquid clay stabilizer according to claim 6, 7, or 8, characterized in that... In the third step, the initiator is one or more of the following: ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. The amount of initiator used is 0.1% to 1% of the total mass of N,N-dimethylethanolamine and allyl chloride. The reaction temperature is 40℃ to 80℃, and the reaction time is 4h to 8h.
10. The method for preparing the urea cationic homopolymer ionic liquid clay stabilizer according to claim 6, 7, 8, or 9, characterized in that... In the third step, the initiator is one or more of the following: ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. The amount of initiator used is 0.1% to 1% of the total mass of N,N-dimethylethanolamine and allyl chloride. The reaction temperature is 40℃ to 80℃, and the reaction time is 4h to 8h.