A sustained-release methylmorpholine internal salt anti-swelling agent and its preparation method

Abstract

This invention discloses a slow-release methylmorpholine internal salt anti-swelling agent and its preparation method, belonging to the field of oilfield fracturing and production enhancement technology. The preparation method includes the following steps: morpholine and dimethyl carbonate are mixed and heated to a first set temperature for reaction, followed by distillation to obtain intermediate I; ethyl chloroacetate is added to intermediate I, and the mixture is stirred and reacted at room temperature before washing to obtain a solid product; the solid product is added to an aqueous hydrochloric acid solution, refluxed at room temperature, and concentrated to obtain intermediate II; N,N-dimethylformamide is added to intermediate II, the pH value is adjusted to a set pH value, then polyamine is added and heated to a second set temperature for reaction, followed by purification and separation to obtain the slow-release methylmorpholine internal salt anti-swelling agent.

Description

Technical Field

[0001] This invention belongs to the field of oilfield fracturing and production enhancement technology, specifically relating to a slow-release methylmorpholine internal salt anti-swelling agent and its preparation method. Background Technology

[0002] Hydraulic fracturing is an important technology for oil and gas resource development. Anti-swelling agents are crucial chemical agents in hydraulic fracturing fluids, effectively inhibiting the hydration, swelling, and dispersion of clay minerals, thus preventing a decrease in reservoir permeability. Existing clay anti-swelling agents are mainly classified into inorganic salts such as potassium chloride and ammonium chloride, cationic polymers, and cationic surfactants.

[0003] Inorganic salt anti-swelling agents are generally used in large quantities and have good short-term anti-swelling effects, but they are prone to ion exchange and loss of anti-swelling effect due to fluid backflow. Cationic polymers are generally high molecular weight polyquaternary ammonium salts. In field applications, due to their large molecular weight, they easily react with anionic treatment agents in fracturing fluids, leading to agent failure and even the formation of precipitates that clog formation pore throats. Cationic surfactant anti-swelling agents can make the formation surface oleophilic, reducing the permeability of oil and gas phases. Therefore, the long-term stability of current anti-swelling agents is insufficient and cannot meet the long-term stability requirements of fracturing technology. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a sustained-release methylmorpholine internal salt anti-swelling agent and its preparation method, thereby obtaining a long-acting anti-swelling agent with sustained-release function through molecular design.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] This invention provides a method for preparing a sustained-release methylmorpholine internal salt anti-swelling agent, comprising the following steps:

[0007] S1: Morpholine and dimethyl carbonate are mixed, heated to a first set temperature, reacted, and then distilled to obtain intermediate I;

[0008] S2: Add ethyl chloroacetate to intermediate I, stir and react at room temperature, then wash to obtain a solid product; add the solid product to hydrochloric acid aqueous solution, reflux at room temperature and then concentrate to obtain intermediate II;

[0009] S3: Add N,N-dimethylformamide to intermediate II, adjust the pH value to the set pH value, then add polyamine and heat to the second set temperature to react, and then purify and separate to obtain sustained-release methylmorpholine internal salt anti-swelling agent.

[0010] In the specific implementation process, the molar ratio of morpholine and dimethyl carbonate is 1:(1~1.2).

[0011] In the specific implementation process, the molar ratio of ethyl chloroacetate to morpholine is (1~1.2):1.

[0012] In the specific implementation process, the mass fraction of the hydrochloric acid aqueous solution is 15%, and the mass ratio of the hydrochloric acid aqueous solution to ethyl chloroacetate is (4~5):1.

[0013] In the specific implementation process, the mass ratio of N,N-dimethylformamide to polyamine is (8~10):1.

[0014] In specific implementation, the polyamine is one of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0015] In the specific implementation process, when the polyamine is ethylenediamine, the molar ratio of polyamine to morpholine is 1:(2~2.2).

[0016] When the polyamine is diethylenetriamine, the molar ratio of polyamine to morpholine is 1:(3~3.2).

[0017] When the polyamine is triethylenetetramine, the molar ratio of polyamine to morpholine is 1:(4~4.2).

[0018] When the polyamine is tetraethylenepentamine, the molar ratio of polyamine to morpholine is 1:(5~5.2).

[0019] In the specific implementation process, the first set temperature is 90~100℃; the set pH value is 7~8; and the second set temperature is 60~70℃.

[0020] This invention provides a sustained-release methylmorpholine internal salt anti-swelling agent prepared according to any one of the preparation methods of the sustained-release methylmorpholine internal salt anti-swelling agent.

[0021] The structural formula of the sustained-release methylmorpholine internal salt anti-swelling agent is as follows:

[0022]

[0023] Where n = 0, 1, 2, or 3.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention provides a method for preparing a sustained-release methylmorpholine internal salt anti-swelling agent. The method involves methylating and carboxymethylating morpholine with dimethyl carbonate and ethyl chloroacetate, followed by an amide reaction with a polyamine to obtain the target product, the sustained-release methylmorpholine internal salt anti-swelling agent. Structurally, the anti-swelling agent prepared by this invention utilizes the reaction of polyamine and morpholine quaternary ammonium salt to form a cationic polymer with significant steric hindrance, making it less likely to react with anionic treatment agents in the fracturing fluid during oilfield fracturing operations. After the amide bond hydrolyzes and breaks, an internal salt anti-swelling agent is generated. Because the internal salt anti-swelling agent molecule contains both positive and negative ionic groups, the intermolecular attraction is strengthened, resulting in superior anti-swelling performance in the fracturing fluid. In terms of application, the anti-swelling agent prepared by this invention has a long-lasting sustained-release effect and can be transported to distant areas. Over time and with increasing formation temperature, the amide bond slowly hydrolyzes to generate small-molecule quaternary ammonium salts, which are adsorbed onto the clay surface, reducing the electrostatic repulsion between clay particles and effectively inhibiting clay swelling.

[0026] In summary, the slow-release methylmorpholine internal salt anti-swelling agent prepared by this invention has long-lasting effect and excellent anti-swelling performance, causes little damage to the formation, and has good compatibility with fracturing fluids, and can be widely used in oilfield fracturing operations. Attached Figure Description

[0027] Figure 1 This diagram illustrates the synthesis and hydrolysis application mechanism of the sustained-release methylmorpholine internal salt anti-swelling agent of the present invention.

[0028] Figure 2 The graph shows the change in the anti-swelling rate of the anti-swelling agent prepared in Example 5 of the present invention under different usage concentrations and times. Detailed Implementation

[0029] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0030] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0031] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0032] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0033] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0034] This invention provides a sustained-release methylmorpholine internal salt anti-swelling agent and its preparation method.

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0036] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0037] See Figure 1 The first aspect of this invention provides a method for preparing a sustained-release methylmorpholine internal salt anti-swelling agent. In the preparation process, dimethyl carbonate and ethyl chloroacetate are used to methylate and carboxymethylate morpholine, followed by an amide reaction with a polyamine to obtain the sustained-release methylmorpholine internal salt anti-swelling agent. The specific steps are as follows:

[0038] 1): Add a certain amount of morpholine and dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 90~100℃ and react for 2~3 h, then distill the product to obtain intermediate I.

[0039] The molar ratio of morpholine to dimethyl carbonate is 1:(1~1.2).

[0040] 2): Add a certain amount of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 8-10 hours. After washing with diethyl ether, a solid product is obtained. Add a certain amount of 15% hydrochloric acid aqueous solution to the solid product, and reflux the reaction at room temperature for 7-8 hours. Concentrate the product to obtain intermediate II.

[0041] The molar ratio of ethyl chloroacetate to morpholine is (1~1.2):1, and the amount of 15% hydrochloric acid aqueous solution added is 4~5 times the mass of ethyl chloroacetate, that is, the mass ratio of hydrochloric acid aqueous solution to ethyl chloroacetate is (4~5):1.

[0042] 3): Add a certain amount of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 7-8, then add a certain amount of polyamine, heat to 60-70℃ and react for 20-24 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0043] The amount of N,N-dimethylformamide added is 8 to 10 times the mass of the polyamine, that is, the mass ratio of N,N-dimethylformamide to polyamine is (8 to 10): 1.

[0044] Polyamines can be one of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0045] In specific implementation, when ethylenediamine is selected as the polyamine, the molar ratio of polyamine to morpholine is 1:(2~2.2). When diethylenetriamine is selected as the polyamine, the molar ratio of polyamine to morpholine is 1:(3~3.2). When triethylenetetramine is selected as the polyamine, the molar ratio of polyamine to morpholine is 1:(4~4.2). When tetraethylenepentamine is selected as the polyamine, the molar ratio of polyamine to morpholine is 1:(5~5.2).

[0046] A second aspect of the present invention provides an anti-swelling agent prepared by the above-described preparation method, the structural formula of which is as follows:

[0047] ;

[0048] Where n = 0, 1, 2, or 3.

[0049] The aforementioned anti-swelling agent exhibits a slow-release effect due to its large steric hindrance and slow hydrolysis. Over time, the amide bonds slowly hydrolyze to form small-molecule quaternary ammonium salts, which are adsorbed onto the clay surface. This reduces the electrostatic repulsion between clay particles, effectively inhibiting clay swelling and making it well-suited for application in oilfield fracturing and production enhancement technologies.

[0050] Example 1

[0051] 1) Add 10 g of morpholine and 10.4 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 90°C and react for 2 h, and distill the product to obtain intermediate I.

[0052] 2) Add 14 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 8 h. After washing with diethyl ether, a solid product is obtained. Add the solid product to 56 g of 15% hydrochloric acid aqueous solution, and reflux the reaction at room temperature for 7 h. Concentrate the product to obtain intermediate II.

[0053] 3) Add 32 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 8, then add 4 g of triethylenetetramine, heat to 60°C and react for 20 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0054] Example 2

[0055] 1) Add 10 g of morpholine and 12.4 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 100°C and react for 3 h, and distill the product to obtain intermediate I.

[0056] 2) Add 16.8 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 10 h. After washing with diethyl ether, a solid product is obtained. Add the solid product to 84 g of 15% hydrochloric acid aqueous solution, and reflux the reaction at room temperature for 8 h. Concentrate the product to obtain intermediate II.

[0057] 3) Add 42.6 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 7, then add 4.26 g of tetraethylenepentamine, heat to 70°C and react for 24 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0058] Example 3

[0059] 1) Add 12 g of morpholine and 12.4 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 90°C and react for 3 h, and distill the product to obtain intermediate I.

[0060] 2) Add 16.9 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 9 h. After washing with diethyl ether, a solid product is obtained. Add the solid product to 68 g of 15% hydrochloric acid aqueous solution, and reflux the reaction at room temperature for 8 h. Concentrate the product to obtain intermediate II.

[0061] 3) Add 40 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 8, then add 4.5 g of diethylenetriamine, heat to 60℃ and react for 24 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0062] Example 4

[0063] 1) Add 14 g of morpholine and 14.5 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 100°C and react for 2 h, and distill the product to obtain intermediate I.

[0064] 2) Add 19.7 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 10 h. Wash with diethyl ether to obtain a solid product. Add the solid product to 90 g of 15% hydrochloric acid aqueous solution, reflux at room temperature for 8 h, and concentrate the product to obtain intermediate II.

[0065] 3) Add 44 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 8, then add 4.4 g of ethylenediamine, heat to 70°C and react for 20 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0066] Example 5

[0067] 1) Add 12 g of morpholine and 14 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 100°C and react for 3 h, and distill the product to obtain intermediate I.

[0068] 2) Add 20 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 10 h. After washing with diethyl ether, a solid product is obtained. Add the solid product to 80 g of 15% hydrochloric acid aqueous solution, and reflux the reaction at room temperature for 8 h. Concentrate the product to obtain intermediate II.

[0069] 3) Add 45 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 7, then add 5 g of triethylenetetramine, heat to 70°C and react for 24 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0070] Example 6

[0071] 1) Add 14 g of morpholine and 15 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 90°C and react for 3 h, and distill the product to obtain intermediate I.

[0072] 2) Add 23 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 9 h. After washing with diethyl ether, a solid product is obtained. Add the solid product to 95 g of 15% hydrochloric acid aqueous solution, and reflux the reaction at room temperature for 8 h. Concentrate the product to obtain intermediate II.

[0073] 3) Add 50 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 7, then add 6 g of tetraethylenepentamine, heat to 60°C and react for 20 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0074] Example 7

[0075] 1) Add 14 g of morpholine and 17.3 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 100°C and react for 3 h, and distill the product to obtain intermediate I.

[0076] 2) Add 23.6 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 9 h. After washing with diethyl ether, a solid product is obtained. Add the solid product to 95 g of 15% hydrochloric acid aqueous solution, and reflux the reaction at room temperature for 8 h. Concentrate the product to obtain intermediate II.

[0077] 3) Add 39 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 8, then add 4.8 g of ethylenediamine, heat to 60°C and react for 24 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0078] Example 8

[0079] 1) Add 12 g of morpholine and 14.8 g of dimethyl carbonate to a three-necked flask equipped with a reflux condenser and an electric stirrer, heat to 100°C and react for 3 h, and distill the product to obtain intermediate I.

[0080] 2) Add 20.2 g of ethyl chloroacetate to intermediate I obtained in step 1), and stir the reaction at room temperature for 9 h. Wash with diethyl ether to obtain a solid product. Add the solid product to 100 g of 15% hydrochloric acid aqueous solution, reflux at room temperature for 7 h, and concentrate the product to obtain intermediate II.

[0081] 3) Add 47 g of N,N-dimethylformamide to intermediate II obtained in step 2), adjust the pH to 7, then add 4.7 g of diethylenetriamine, heat to 70°C and react for 20 h, and purify and separate the product by toluene column chromatography to obtain the sustained-release methylmorpholine internal salt anti-swelling agent.

[0082] To evaluate the anti-swelling effect of the slow-release methylmorpholine internal salt anti-swelling agent, the anti-swelling agent prepared in Example 5 was formulated into 0.5%, 1%, and 2% aqueous solutions, and its anti-swelling rate at 90°C was tested at different times. The test method followed SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizers for Fracturing, Acidizing, and Water Injection in Oil and Gas Fields". The test results are as follows. Figure 2 As shown, from Figure 2 It can be seen that the anti-swelling agent prepared in Example 5 has good long-lasting anti-swelling performance. When the dosage is 2%, the anti-swelling rate can reach more than 90%, which can be used as a long-lasting anti-swelling agent in the field of oilfield fracturing and production enhancement technology.

[0083] The results of the compatibility test between the anti-swelling agent prepared in Examples 1-6 and other additives in the fracturing fluid showed that no precipitation or residue was found in the fracturing fluid with 2% anti-swelling agent added after 24 hours, indicating that the anti-swelling agent of the present invention has good compatibility with other additives in the fracturing fluid.

[0084] To evaluate the water wash resistance of the slow-release methylmorpholine internal salt anti-swelling agent, the anti-swelling agent prepared in Example 5 was formulated into 0.5%, 1%, and 2% aqueous solutions, and their water wash resistance was tested at 90℃ for 72 h. The test method followed SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizers for Fracturing, Acidizing, and Water Injection in Oil and Gas Fields". The test results are shown in Table 1. As can be seen from Table 1, the anti-swelling agent prepared in Example 5 has good water wash resistance; after three washes, the water wash resistance rate is greater than 90%.

[0085] Table 1. Water wash resistance of anti-swelling agents at different concentrations

[0086]

[0087] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a sustained-release methylmorpholine internal salt anti-swelling agent, characterized in that, Includes the following steps: S1: Morpholine and dimethyl carbonate are mixed, heated to a first set temperature, reacted, and then distilled to obtain intermediate I; S2: Add ethyl chloroacetate to intermediate I, stir the reaction at room temperature, and then wash to obtain a solid product; The solid product was added to an aqueous hydrochloric acid solution, refluxed at room temperature, and then concentrated to obtain intermediate II; S3: Add N,N-dimethylformamide to intermediate II, adjust the pH value to the set pH value, then add polyamine and heat to the second set temperature to react, then purify and separate to obtain sustained-release methylmorpholine internal salt anti-swelling agent; The polyamine is one of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; The structural formula of the sustained-release methylmorpholine internal salt anti-swelling agent is as follows: Where n = 0, 1, 2, or 3.

2. The method for preparing the sustained-release methylmorpholine internal salt anti-swelling agent according to claim 1, characterized in that, The molar ratio of morpholine to dimethyl carbonate is 1:(1~1.2).

3. The method for preparing the sustained-release methylmorpholine internal salt anti-swelling agent according to claim 1, characterized in that, The molar ratio of ethyl chloroacetate to morpholine is (1~1.2):

1.

4. The preparation method of the sustained-release methylmorpholine internal salt anti-swelling agent according to claim 1, characterized in that, The hydrochloric acid aqueous solution has a mass fraction of 15%, and the mass ratio of the hydrochloric acid aqueous solution to ethyl chloroacetate is (4~5):

1.

5. The method for preparing the sustained-release methylmorpholine internal salt anti-swelling agent according to claim 1, characterized in that, The mass ratio of N,N-dimethylformamide to polyamine is (8~10):

1.

6. The method for preparing the sustained-release methylmorpholine internal salt anti-swelling agent according to claim 1, characterized in that, When the polyamine is ethylenediamine, the molar ratio of polyamine to morpholine is 1:(2~2.2). When the polyamine is diethylenetriamine, the molar ratio of polyamine to morpholine is 1:(3~3.2). When the polyamine is triethylenetetramine, the molar ratio of polyamine to morpholine is 1:(4~4.2). When the polyamine is tetraethylenepentamine, the molar ratio of polyamine to morpholine is 1:(5~5.2).

7. The method for preparing the sustained-release methylmorpholine internal salt anti-swelling agent according to claim 1, characterized in that, The first set temperature is 90~100℃; the set pH value is 7~8; the second set temperature is 60~70℃.

8. A sustained-release methylmorpholine internal salt anti-swelling agent prepared by the preparation method of any one of claims 1 to 7.

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