Oligomeric cationic quaternary ammonium salt clay stabilizer and preparation method thereof

Abstract

The invention relates to the technical field of clay stabilizers, in particular to an oligomeric cationic quaternary ammonium salt clay stabilizer and a preparation method thereof. The preparation method of the oligomeric cationic quaternary ammonium salt clay stabilizer comprises the following steps: reacting N-methylaniline with epichlorohydrin under a first reaction condition to generate a target monomer; carrying out self-polymerization reaction on the target monomer under a second reaction condition to generate a target polymer; carrying out hydrolysis reaction on the target polymer to generate a crude product; and carrying out impurity removal treatment on the crude product to obtain the oligomeric cationic quaternary ammonium salt clay stabilizer. The anti-swelling performance and the washing resistance of the oligomeric cationic quaternary ammonium salt clay stabilizer are remarkably improved, the preparation mechanism is clear, the reaction conditions are simple, the post-treatment operation is simple and convenient, and large-scale production is easy.

Description

Technical Field

[0001] The invention belongs to the technical field of clay stabilizers, and particularly relates to an oligomeric cationic quaternary ammonium salt clay stabilizer and a preparation method thereof. Background Art

[0002] During the water injection development process of oil fields, the clay minerals in the formation will hydrate and expand when exposed to water, which will cause the formation pores to be blocked, seriously reducing the reservoir permeability. The main reason for this is that the main components of clay minerals are montmorillonite and kaolin, etc. Clay minerals carry a large amount of negative charges. After hydration when exposed to water, the repulsion between the negative charges causes the volume of clay minerals to expand rapidly, thereby blocking the pores in the reservoir and affecting the increase in oil and gas production.

[0003] At present, the main clay anti-swelling measure in oil production is to inject clay stabilizers into clay minerals to reduce the swelling of clay minerals when they come into contact with water. Conventional clay stabilizers mainly include potassium chloride and small molecule quaternary ammonium salts. Among them, the atomic radius of potassium ions in potassium chloride is small, which can enter the interior of clay minerals to form a double electron layer, thereby reducing the swelling of clay minerals; while small molecule quaternary ammonium salts neutralize charges and reduce the negative charge density, thereby reducing the swelling of clay.

[0004] The advantage of the above conventional clay stabilizers is that the anti-swelling rate is relatively high, but the disadvantage is that during the process of injecting water into the formation, inorganic salts and small molecular quaternary ammonium salts are easily washed away, causing their concentration to decrease rapidly, resulting in problems such as poor resistance to water washing and poor anti-swelling stability. Summary of the invention

[0005] The purpose of the present application is to provide an oligomeric cationic quaternary ammonium salt clay stabilizer and a preparation method thereof in view of the poor anti-swelling effect and poor water-resistance of conventional clay stabilizers. The embodiments of the present application are implemented as follows:

[0006] The first aspect of the embodiments of the present application provides an oligomeric cationic quaternary ammonium salt clay stabilizer having the following structural formula:

[0007]

[0008] Among them, n=3-10.

[0009] A second aspect of the embodiment of the present application provides a method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer, the preparation method comprising the following steps:

[0010] N-methylaniline and epichlorohydrin react under a first reaction condition to generate a target monomer;

[0011] Under the second reaction condition, the target monomer undergoes a self-polymerization reaction to generate a target polymer;

[0012] The target polymer is subjected to a hydrolysis reaction to generate a crude product;

[0013] The crude product is subjected to impurity removal treatment to obtain an oligomeric cationic quaternary ammonium salt clay stabilizer.

[0014] In some embodiments, the molar ratio of N-methylaniline to epichlorohydrin is 1:0.95-1.05, and the first reaction conditions include a reaction temperature of 50° C.-60° C. and a reaction time of 1 h-1.5 h.

[0015] In some embodiments, the second reaction conditions include a reaction temperature of 70°C-90°C and a reaction time of 1h-2h.

[0016] In some embodiments, the hydrolysis reaction of the target polymer includes: reacting the target polymer with potassium hydroxide.

[0017] In some embodiments, the amount of potassium hydroxide used is 1%-2% of the sum of the mass of N-methylaniline and epichlorohydrin.

[0018] In some embodiments, the crude product is subjected to impurity removal treatment to obtain an oligomeric cationic quaternary ammonium salt clay stabilizer, comprising:

[0019] Adjust pH to neutral;

[0020] A mixed solvent consisting of an organic solvent and water is selected as an extractant, and the crude product is extracted at least three times with the extractant to separate an organic phase;

[0021] Rotary evaporation is performed on the organic phase to obtain an oligomeric cationic quaternary ammonium salt clay stabilizer;

[0022] The organic solvent includes toluene or methyl isobutyl ketone, and the mass ratio of the organic solvent to water in the extractant is 1-3:1.

[0023] Beneficial effects of the present application: The main chain segments of the oligocationic quaternary ammonium salt clay stabilizer of the present application have a high cation density, which can neutralize the negative charge of the clay mineral to a great extent, thereby greatly reducing the negative charge density to achieve the purpose of reducing the swelling effect of the clay mineral; and there are a large number of benzene ring groups and polar hydroxyl groups in the oligocationic quaternary ammonium salt clay stabilizer, which can form multi-point effective adsorption with the hydrophobic structure or polar structure on the surface of the clay mineral in the formation environment, effectively preventing the secondary swelling of the clay mineral caused by the reduction of cations in the clay due to hydraulic scouring; further, the positive charge carried by the quaternary ammonium cation of the oligocationic quaternary ammonium salt clay stabilizer of the present application can form multi-point tight adsorption with the negative charge carried by the clay mineral, effectively overcoming the problem of loss of the clay stabilizer or reduction in concentration due to water washing. It can be seen that the oligocationic quaternary ammonium salt clay stabilizer of the present application exhibits excellent water washability and anti-swelling effects;

[0024] At the same time, the residual organic chlorine of the oligomeric cationic quaternary ammonium salt clay stabilizer of the present application is 0, which can avoid the problem of catalyst failure in the crude oil refining stage;

[0025] The preparation mechanism of the oligomeric cationic quaternary ammonium salt clay stabilizer of the present application is clear, the reaction conditions are simple, the post-treatment operation is simple, and it is easy to scale up the production. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0027] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0028] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0029] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0031] The oligomeric cationic quaternary ammonium salt clay stabilizer, the preparation and application of the oligomeric cationic quaternary ammonium salt clay stabilizer provided in the present application are further described below in conjunction with specific examples.

[0032] The first aspect of the embodiments of the present application provides an oligomeric cationic quaternary ammonium salt clay stabilizer having the following structural formula:

[0033]

[0034] Among them, n=3-10.

[0035] A second aspect of the embodiment of the present application provides a method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer, the preparation method comprising the following steps:

[0036] N-methylaniline and epichlorohydrin react under a first reaction condition to generate a target monomer;

[0037] Under the second reaction condition, the target monomer undergoes a self-polymerization reaction to generate a target polymer;

[0038] The target polymer is subjected to a hydrolysis reaction to generate a crude product;

[0039] The above steps are expressed by the reaction equation as follows:

[0040]

[0041] Where n = 3-10;

[0042] Finally, the crude product is subjected to impurity removal treatment to obtain an oligomeric cationic quaternary ammonium salt clay stabilizer.

[0043] In some embodiments, the molar ratio of N-methylaniline to epichlorohydrin is 1:0.95-1.05, and the first reaction conditions include a reaction temperature of 50° C.-60° C. and a reaction time of 1 h-1.5 h.

[0044] In some embodiments, the second reaction conditions include a reaction temperature of 70°C-90°C and a reaction time of 1h-2h.

[0045] In some embodiments, the hydrolysis reaction of the target polymer includes: reacting the target polymer with potassium hydroxide.

[0046] In some embodiments, the amount of potassium hydroxide used is 1%-2% of the sum of the mass of N-methylaniline and epichlorohydrin.

[0047] In some embodiments, the crude product is subjected to extraction, comprising:

[0048] A mixed solvent consisting of an organic solvent and water is selected as an extractant, and the crude product is extracted at least three times with the extractant;

[0049] The organic solvent includes toluene or methyl isobutyl ketone, and the mass ratio of the organic solvent to water in the extractant is 1-3:1.

[0050] The oligomeric cationic quaternary ammonium salt clay stabilizer and its preparation are described below in conjunction with specific examples.

[0051] Example 1

[0052] Add reactants N-methylaniline (107 g, 1 mol) and methanol (50 g, i.e., solvent) into a small glass reactor, heat to 55°C, and then slowly add epichlorohydrin (95.3 g, 1.03 mol) dropwise. Add the mixture over 1 hour. Keep the temperature in the reactor at 55°C during the addition. After the addition is complete, heat to 70°C and keep warm for 2 hours.

[0053] Then, potassium hydroxide solution (20% concentration, 15 g in total) was added in batches until the pH in the reactor stabilized at 9 and did not decrease any more. It should be noted that the amount of potassium hydroxide used here was 3 g;

[0054] Next, hydrochloric acid is added to maintain the pH at neutral, and then extraction is carried out with an extractant composed of methyl isobutyl ketone and water (the mass ratio of methyl isobutyl ketone to water is 2:1), and the aqueous phase containing inorganic salts is separated. The organic phase is then subjected to rotary evaporation with a rotary evaporator to remove the solvent, and finally a light yellow solid product is obtained, which is an oligomeric cationic quaternary ammonium salt clay stabilizer.

[0055] Example 2

[0056] Add reactants N-methylaniline (107 g, 1 mol) and methanol (50 g, i.e., solvent) into a small glass reactor, heat to 50°C, and then slowly add epichlorohydrin (97.1 g, 1.05 mol) dropwise. Add the mixture over 1.2 hours. Keep the temperature in the reactor at 50°C during the addition. After the addition is complete, heat to 80°C and keep warm for 1.5 hours.

[0057] Then, potassium hydroxide solution (20% concentration, 20 g in total) was added in batches until the pH in the reactor stabilized at 9 and did not decrease any more. It should be noted that the amount of potassium hydroxide used here was 4 g;

[0058] Next, hydrochloric acid is added to maintain the pH at neutral, and then extraction is carried out with an extractant consisting of methyl isobutyl ketone and water (the mass ratio of toluene to water is 3:1), the aqueous phase containing inorganic salts is separated, and the organic phase is further rotary evaporated with a rotary evaporator to remove the solvent, and finally a light yellow solid product is obtained, which is an oligomeric cationic quaternary ammonium salt clay stabilizer.

[0059] Example 3

[0060] Add reactants N-methylaniline (107 g, 1 mol) and methanol (50 g, i.e., solvent) into a small glass reactor, heat to 60°C, and then slowly add epichlorohydrin (90.7 g, 0.98 mol) dropwise. Add the mixture over 1.2 hours. Keep the temperature in the reactor at 60°C during the addition. After the addition is complete, heat to 90°C and keep warm for 1.5 hours.

[0061] Then, potassium hydroxide solution (20% concentration, 20 g in total) was added in batches until the pH in the reactor stabilized at 8 and did not decrease any more. It should be noted that the amount of potassium hydroxide used here was 2 g;

[0062] Next, hydrochloric acid is added to maintain the pH at neutral, and then extraction is carried out with an extractant consisting of methyl isobutyl ketone and water (the mass ratio of toluene to water is 4:1), the aqueous phase containing inorganic salts is separated, and the organic phase is further rotary evaporated with a rotary evaporator to remove the solvent, and finally a light yellow solid product is obtained, which is an oligomeric cationic quaternary ammonium salt clay stabilizer.

[0063] Example 4

[0064] Add reactants N-methylaniline (107 g, 1 mol) and methanol (50 g, i.e., solvent) into a small glass reactor, heat to 60°C, and then slowly add epichlorohydrin (92.5, 1 mol) dropwise. The addition is completed within 1.2 hours. During the addition, the temperature in the reactor is maintained at 60°C. After the addition is completed, heat to 90°C and keep warm for 1.5 hours.

[0065] Then, potassium hydroxide solution (15% concentration, 27 g in total) was added in batches until the pH in the reactor stabilized at 9 and did not decrease any more. It should be noted that the amount of potassium hydroxide used here was 4 g;

[0066] Next, hydrochloric acid is added to maintain the pH at neutral, and then extraction is carried out with an extractant composed of methyl isobutyl ketone and water (the mass ratio of methyl isobutyl ketone to water is 2:1), and the aqueous phase containing inorganic salts is separated. The organic phase is then subjected to rotary evaporation with a rotary evaporator to remove the solvent, and finally a light yellow solid product is obtained, which is an oligomeric cationic quaternary ammonium salt clay stabilizer.

[0067] Anti-swelling performance and water washability test

[0068] The clay stabilizer provided in the above examples, the comparative example 1-saturated potassium chloride aqueous solution, and the comparative example 2-50% choline chloride clay stabilizer were used to perform anti-swelling performance and water washability tests according to SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizer for Oil and Gas Field Fracturing Acidification and Water Injection". The specific performance test results are shown in Table 1.

[0069] It should be noted that the formula and proportion of the choline chloride clay stabilizer in the comparative example 2-50% are as follows: the mass ratio of choline chloride, potassium chloride and water is 40:10:50.

[0070] Table 1 Performance test results

[0071]

[0072] As can be seen from Table 1, compared with the small molecule potassium chloride clay stabilizer, the anti-swelling rate of the clay stabilizer of the present application is significantly improved, and the water washing resistance rate is significantly improved. Compared with the choline chloride clay stabilizer with a shorter segment, the anti-swelling performance of the clay stabilizer of the present application is slightly improved, and the water washing resistance rate of the clay stabilizer of the present application is more excellent. This is because: the quaternary ammonium salt positive charge of the oligomeric cationic quaternary ammonium salt clay stabilizer can be closely adsorbed with the negative charge on the surface of the clay mineral, thereby improving the water washing resistance. Moreover, the oligomeric cationic quaternary ammonium salt clay stabilizer contains benzene ring groups and polar hydroxyl groups, and the number of the two groups is large, which can form effective adsorption with the hydrophobic structure or polar structure on the surface of the clay mineral in the formation environment. At the same time, the main chain segment of the oligomeric cationic quaternary ammonium salt clay stabilizer has a high cation density, which can neutralize the negative charge of the clay mineral to a great extent, and greatly reduce the negative charge density to achieve the purpose of reducing the swelling effect of the clay mineral. Therefore, the clay stabilizer prepared in the embodiment of the present application has relatively excellent anti-swelling performance and water washing resistance.

[0073] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. An oligomeric cationic quaternary ammonium salt clay stabilizer, characterized in that: Has the following structural formula: Among them, n=3-10.

2. A method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer, characterized in that: The preparation method comprises the following steps: N-methylaniline and epichlorohydrin react under a first reaction condition to generate a target monomer; Under the second reaction condition, the target monomer undergoes a self-polymerization reaction to generate a target polymer; The target polymer is subjected to a hydrolysis reaction to generate a crude product; The crude product is subjected to impurity removal treatment to obtain an oligomeric cationic quaternary ammonium salt clay stabilizer.

3. The method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer according to claim 2, characterized in that: The molar ratio of N-methylaniline to epichlorohydrin is 1:0.95-1.05, and the first reaction conditions include a reaction temperature of 50-60° C. and a reaction time of 1 h-1.5 h.

4. The method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer according to claim 2, characterized in that: The second reaction conditions include a reaction temperature of 70°C-90°C and a reaction time of 1h-2h.

5. The method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer according to claim 2, characterized in that: The hydrolysis reaction of the target polymer includes: reacting the target polymer with potassium hydroxide.

6. The method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer according to claim 5, characterized in that: The amount of potassium hydroxide used is 1%-2% of the sum of the mass of N-methylaniline and epichlorohydrin.

7. The method for preparing an oligomeric cationic quaternary ammonium salt clay stabilizer according to claim 2, characterized in that: The crude product is subjected to impurity removal treatment to obtain an oligomeric cationic quaternary ammonium salt clay stabilizer, comprising: Adjust pH to neutral; A mixed solvent consisting of an organic solvent and water is selected as an extractant, and the crude product is extracted at least three times with the extractant to separate an organic phase; Rotary evaporation is performed on the organic phase to obtain an oligomeric cationic quaternary ammonium salt clay stabilizer; The organic solvent includes toluene or methyl isobutyl ketone, and the mass ratio of the organic solvent to water in the extractant is 1-3:1.

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