A clay stabilizer containing a cationic polymer and a method for preparing the same

Abstract

The application relates to a clay stabilizer containing a cationic polymer and a preparation method thereof, and belongs to the technical field of oil field chemistry. The preparation method comprises the following steps: uniformly mixing tetramethyl ethylenediamine, 1,3-dichloro-2-propanol and a hydrogen bond donor, then heating to a first temperature, reacting at the first temperature for a first time period, then heating to a second reaction temperature, reacting at the second temperature for a second time period, and stopping the reaction to obtain the clay stabilizer containing the cationic polymer. The clay stabilizer comprises a cationic polymer formed by the reaction of tetramethyl ethylenediamine and 1,3-dichloro-2-propanol and a hydrogen bond donor, and the cationic polymer and the hydrogen bond donor form an ionic liquid solvent, therefore, the clay stabilizer does not need to use volatile, flammable and explosive organic solvents, and the preparation method is simple, the reaction process is safe and controllable, and is suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil field chemistry, and particularly relates to a clay stabilizer containing a cationic polymer and a preparation method thereof. BACKGROUND

[0002] In the process of oil and gas exploitation and water injection operation, the clay minerals (such as montmorillonite, illite, kaolinite, etc.) in the formation are prone to hydration swelling and dispersion migration after being contacted with water, resulting in a decrease in reservoir permeability and a decrease in wellbore stability, and even causing wellbore collapse or oil well production reduction in severe cases. According to statistics, about 70% of the oil and gas reservoirs in the world have different degrees of clay damage problems, which directly affect the development efficiency and economy of oil and gas fields. Therefore, a clay stabilizer is usually added to the well fluid to prevent the hydration swelling and dispersion migration of clay. Generally, the surface of clay particles is negatively charged, and the cations in the clay stabilizer are positively charged, so that the two can produce strong adsorption through electrostatic attraction, delay the penetration of water molecules, and prevent the hydration swelling of clay particles, thereby playing an inhibitory role.

[0003] In the early stage, inorganic salts such as KCl and NH4Cl were used as clay stabilizers to inhibit clay hydration through ion exchange, but the dosage was large, the effect was short-acting, high concentration could easily corrode equipment, and it would also have some impact on the performance of the well fluid. In the 1960s and 1970s, aluminum hydroxide or zirconium hydroxide was used as a clay stabilizer, which had problems such as poor temperature resistance and poor acid resistance. In recent years, the commonly used clay stabilizers mainly include quaternary ammonium salt surfactants, polyamines, and polyquaternary ammonium salts. The above clay stabilizers all have good anti-swelling effect, but also have some problems: the production process of polyamine clay stabilizer is relatively complex, the water washing resistance is poor, and the effective period is short; the molecular weight of polyquaternary ammonium salt clay stabilizer is large, which is not suitable for low permeability reservoirs, and will increase the damage to the permeability of low permeability reservoirs; the quaternary ammonium salt surfactant will make the reservoir become oil-wet, thereby reducing the oil phase permeability, which is not conducive to oil exploitation; in addition, the above types of clay stabilizers have poor compatibility with fracturing fluid (especially polyacrylamide), which can greatly reduce the viscosity of the fracturing fluid system, affect the sand carrying performance, and increase the difficulty of sand addition.

[0004] In recent years, researchers have been committed to developing composite clay stabilizers to improve performance through synergistic effects (such as cation-anion complex, nano material modification, etc.). However, the existing composite systems still have problems such as complex formula, poor stability, or high cost, and there is an urgent need to develop a new type of clay stabilizer that is efficient, long-acting, and environmentally friendly. SUMMARY

[0005] In view of the above problems, the present application provides a clay stabilizer containing a cationic polymer and a preparation method thereof.

[0006] The first object of the present application is to provide a preparation method of a clay stabilizer containing a cationic polymer, comprising:

[0007] Mixing the tetramethyl ethylenediamine, 1,3-dichloro-2-propanol and the hydrogen bond donor uniformly, then heating to a first temperature, and reacting at the first temperature for a first time period, then heating to a second reaction temperature, and reacting at the second temperature for a second time period, stopping the reaction, to obtain the clay stabilizer containing cationic polymer.

[0008] In specific embodiments of the present application, the hydrogen bond donor is one or more of urea, ethylene glycol and glycerol;

[0009] In specific embodiments of the present application, the first temperature is 40-60℃, and the first time period is 4-8h. Preferably, the first temperature is 50℃ or 60℃, and the first time period is 8h.

[0010] In specific embodiments of the present application, the second temperature is 80-100℃, and the second time period is 6-24h. Preferably, the second temperature is 80℃, 90℃ or 100℃, and the second time period is 12h or 24h.

[0011] In specific embodiments of the present application, the molar ratio of 1,3-dichloro-2-propanol, tetramethyl ethylenediamine and hydrogen bond donor is 0.8-1.0:1:1-4.

[0012] In specific embodiments of the present application, water is added and stirred uniformly during the stopping of the reaction.

[0013] In specific embodiments of the present application, the molar ratio of tetramethyl ethylenediamine and water is 1:0-2.

[0014] A second object of the present application is to provide a clay stabilizer containing cationic polymer, which is prepared by the following steps:

[0015] Mixing the tetramethyl ethylenediamine, 1,3-dichloro-2-propanol and the hydrogen bond donor uniformly, then heating to a first temperature, and reacting at the first temperature for a first time period, then heating to a second reaction temperature, and reacting at the second temperature for a second time period, stopping the reaction, to obtain the clay stabilizer containing cationic polymer.

[0016] In specific embodiments of the present application, the clay stabilizer has an anti-swelling rate of ≥85%, a water washing anti-swelling rate of ≥85%, a gel viscosity retention rate of ≥90%, and a temperature resistance of up to 300℃.

[0017] The present application has the following beneficial effects:

[0018] The application discloses a clay stabilizer containing a cationic polymer and a preparation method thereof, wherein the clay stabilizer comprises a cationic polymer formed by the reaction of tetramethyl ethylenediamine and 1,3-dichloro-2-propanol and a hydrogen bond donor, the cationic polymer and the hydrogen bond donor form an ionic liquid solvent, and the preparation process of the stabilizer is that the tetramethyl ethylenediamine, the 1,3-dichloro-2-propanol and the hydrogen bond donor are directly mixed, the tetramethyl ethylenediamine and the 1,3-dichloro-2-propanol are reacted, the hydrogen bond donor does not participate in the reaction of the two, the cationic polymer generated by the reaction of the tetramethyl ethylenediamine and the 1,3-dichloro-2-propanol immediately reacts with the hydrogen bond donor to generate the ionic liquid solvent, so that the preparation process of the stabilizer is synchronous with the formation process of the cationic polymer, no volatile, flammable and explosive organic solvent needs to be used, and the preparation method is simple, the reaction process is safe and controllable, and is suitable for large-scale production.

[0019] The cationic polymer in the application is a strong polar molecule containing multiple cations and hydroxyl groups, has high charge density, and has remarkable effects of preventing clay swelling; the cationic polymer has multiple adsorption sites and high water washing resistance.

[0020] Water can be introduced in the preparation process of the stabilizer to form a water-containing stabilizer.

[0021] The clay stabilizer has strong temperature resistance and can be used in high-temperature and ultra-high-temperature reservoirs.

[0022] The clay stabilizer has little influence on the viscosity of a guar gum fracturing fluid, can guarantee the sand carrying performance of the fracturing fluid, and can be used in low-permeability and ultra-low-permeability reservoir reconstruction or water injection development.

[0023] Other features and advantages of the application will be set forth in the following description, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. The objects and other advantages of the application can be realized and attained by the structure particularly pointed out in the written description and claims. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions and advantages of the embodiments of the application clearer, the following will combine the embodiments of the application to clearly and completely explain the technical solutions in the embodiments of the application. Obviously, the described embodiments are some embodiments of the application but not all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0025] According to the preparation method of the clay stabilizer containing the cationic polymer, the following steps are included.

[0026] Mixing tetramethyl ethylene diamine, 1,3-dichloro-2-propanol and hydrogen bond donor uniformly, heating to the first temperature, and reacting at the first temperature for the first time period, then heating to the second reaction temperature, and reacting at the second temperature for the second time period, stopping the reaction, to obtain the clay stabilizer containing cationic polymer.

[0027] Example 1:

[0028] 12.0g of tetramethyl ethylene diamine, 12.9g of 1,3-dichloro-2-propanol and 12.0g of urea are mixed uniformly, reacted at 60°C for 8h, reacted at 100°C for 24h, 3.1g of tap water is added to terminate the reaction, stirred uniformly, to obtain the clay stabilizer containing cationic polymer.

[0029] Example 2:

[0030] 12.0g of tetramethyl ethylene diamine, 12.9g of 1,3-dichloro-2-propanol and 12.4g of ethylene glycol are mixed uniformly, reacted at 60°C for 8h, reacted at 90°C for 12h, 2.7g of tap water is added to terminate the reaction, stirred uniformly, to obtain the clay stabilizer containing cationic polymer.

[0031] Example 3:

[0032] 12.0g of tetramethyl ethylene diamine, 12.9g of 1,3-dichloro-2-propanol, 6.0g of urea and 6.2g of ethylene glycol are mixed uniformly, reacted at 50°C for 8h, reacted at 90°C for 12h, 2.9g of tap water is added to terminate the reaction, stirred uniformly, to obtain the clay stabilizer containing cationic polymer.

[0033] Example 4:

[0034] 12.0g of tetramethyl ethylene diamine, 12.9g of 1,3-dichloro-2-propanol, 12.0g of urea and 12.4g of ethylene glycol are mixed uniformly, reacted at 50°C for 6h, reacted at 80°C for 12h, cooled to room temperature, stirred uniformly, to obtain the clay stabilizer containing cationic polymer.

[0035] Example 5:

[0036] 12.0g of tetramethyl ethylene diamine, 12.9g of 1,3-dichloro-2-propanol, 9.2g of glycerol and 6.2g of ethylene glycol are mixed uniformly, reacted at 50°C for 6h, reacted at 80°C for 12h, cooled to room temperature, stirred uniformly, to obtain the clay stabilizer containing cationic polymer.

[0037] Comparative Example 1:

[0038] 12.0 g of tetramethyl ethylenediamine was dissolved in 12.9 g of 1,3-dichloro-2-propanol in 100 mL of anhydrous ethanol, and refluxed at 60°C for 8 h, and refluxed at 80°C for 12 h, and the solvent was recovered by rotary evaporation, precipitated with ethyl acetate, filtered and vacuum dried to obtain a white solid, which was a cationic polymer, with a yield of 98.6%.

[0039] Performance test

[0040] The evaluation method refers to the centrifugal method in SY / T5971-2024 “Performance Evaluation Method of Clay Stabilizer for Oil and Gas Field Fracturing Acidizing and Water Injection” to test the anti-swelling rate, water washing resistance and viscosity retention rate.

[0041] Test Example 1 Evaluation of Anti-swelling Rate of Clay Stabilizer

[0042] Take 0.5 g of clay stabilizer, add 100 g of distilled water and shake well to obtain a clay stabilizer solution. Weigh 0.50 g of sodium bentonite, put it into a 10 mL centrifuge tube, add 10 mL of clay stabilizer solution, shake well, and place it at room temperature for 2 h, then put it into a centrifuge at a speed of 1500 r / min for 15 min, and read the volume V1 of the swelled sodium bentonite.

[0043] Replace the clay stabilizer solution with distilled water, and the volume V2 of the swelled sodium bentonite.

[0044] Replace the clay stabilizer solution with kerosene, and the volume V0 of the swelled sodium bentonite.

[0045] The anti-swelling rate B is calculated as shown in formula (1):

[0046] (1)

[0047] Test Example 2 Evaluation of Water Washing Resistance of Clay Stabilizer

[0048] Discard the supernatant in the centrifuge tube after centrifugation in Test Example 1, add 10 mL of distilled water, shake well, and stand for 2 h, then put it into a centrifuge at a speed of 1500 r / min for 15 min, repeat the above operation twice, read the volume of the swelled sodium bentonite, and the anti-swelling rate is calculated in the same way as Test Example 1.

[0049] Test Example 3 Evaluation of Gel Viscosity Retention Rate of Clay Stabilizer

[0050] Prepare 1000 mL of 0.4% hydroxypropyl guanidine gum fracturing fluid base fluid, divide it into two parts, one part is blank, and the other part is added with 0.7% clay stabilizer by mass fraction.

[0051] The crosslinking liquid formula of the fracturing fluid is prepared by 3.0% sodium tetraborate and 10.0% sodium hydroxide by mass fraction.

[0052] Two fracturing fluid base fluids are prepared into fracturing fluid gels according to the crosslinking ratio required by the test or the crosslinking ratio of 100:1, and then the apparent viscosities of the two gel samples at 90 DEG C are measured respectively.

[0053] The calculation of the gel viscosity retention rate is shown in formula (2):

[0054] (2)

[0055] In formula (2), y1 is the viscosity retention rate, expressed by percentage; η2 is the apparent viscosity after adding the clay stabilizer, mPa s; η1 is the apparent viscosity of the blank sample, mPa s.

[0056] The test results of the gel viscosity retention rate of the clay stabilizer of the present application are shown in Table 1.

[0057] The clay stabilizer solution is placed in a high-temperature and high-pressure heat treatment sealed container, and heat treated at 300 DEG C for 2h, and the above operation is repeated, the temperature resistance of the clay stabilizer is tested, and the test results are shown in Table 1.

[0058] Table 1 Test results

[0059]

[0060] From the test results, the anti-swelling rate of the clay stabilizer prepared in the present application is ≥85%, the water washing anti-swelling rate is ≥85%, the gel viscosity retention rate is ≥90%, the temperature resistance reaches 300 DEG C, and the performance is excellent, which can be used for fracturing reconstruction of high-temperature, ultra-high-temperature, low-permeability and ultra-low-permeability reservoirs; compared with the clay stabilizer in Comparative Example 1 (which is a pure cationic polymer), the clay stabilizer prepared in the present application (including a cationic polymer and a hydrogen bond donor, or including a cationic polymer, a hydrogen bond donor and water), the preparation method is simpler, the price is lower, the amount of cationic polymer is reduced, and it still has good anti-swelling rate, water washing anti-swelling rate, and better compatibility with guar gum fracturing fluid.

[0061] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a clay stabilizer containing a cationic polymer, characterized in that, include: Tetramethylethylenediamine, 1,3-dichloro-2-propanol and hydrogen bond donor were mixed evenly, heated to a first temperature and reacted for a first time period at the first temperature, then heated to a second reaction temperature and reacted for a second time period at the second temperature, and the reaction was stopped to obtain a clay stabilizer containing cationic polymer. The hydrogen bond donor is one or more of urea, ethylene glycol, and glycerol; The first temperature is 40~60℃, and the first time period is 4~8h; The second temperature is 80~100℃, and the second time period is 6~24h; The molar ratio of 1,3-dichloro-2-propanol, tetramethylethylenediamine, and the hydrogen bond donor is 0.8~1.0:1:1~4.

2. The method for preparing a clay stabilizer containing a cationic polymer according to claim 1, characterized in that, The first temperature is 50°C or 60°C.

3. The method for preparing a clay stabilizer containing a cationic polymer according to claim 1, characterized in that, The first time period is 8 hours.

4. The method for preparing a clay stabilizer containing a cationic polymer according to claim 1, characterized in that, The second temperature is 80°C, 90°C, or 100°C.

5. The method for preparing a clay stabilizer containing a cationic polymer according to claim 1, characterized in that, The second time period is 12 hours or 24 hours.

6. A method for preparing a clay stabilizer containing a cationic polymer according to any one of claims 1-5, characterized in that, During the process of stopping the reaction, water is added and stirred until homogeneous.

7. The method for preparing a clay stabilizer containing a cationic polymer according to claim 6, characterized in that, The molar ratio of tetramethylethylenediamine to water is 1:0~2.

8. A clay stabilizer containing a cationic polymer, characterized in that, It is prepared by any one of the preparation methods described in claims 1-7.

9. A clay stabilizer containing a cationic polymer according to claim 8, characterized in that, The clay stabilizer has an anti-swelling rate of ≥85%, a water-washed anti-swelling rate of ≥85%, and a gel viscosity retention rate of ≥90%.

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