A self-emulsifying resin curing agent, a curing system and a preparation method thereof

Abstract

The application belongs to the field of oil field chemicals, and particularly relates to a self-emulsifying resin curing agent, a curing system and a preparation method thereof. The preparation method of the self-emulsifying epoxy curing agent comprises the following steps: (1) mixing an epoxy resin E-44 solution with triethylenetetramine, and reacting to obtain a modified epoxy resin; (2) adding 2,3-epoxypropyltrimethylammonium chloride into the modified epoxy resin, and reacting to obtain the self-emulsifying epoxy curing agent. The self-emulsifying curing agent has high adaptability, small addition amount and simple on-site construction process. The self-emulsifying resin curing system for resin cement has significantly improved toughness and corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemicals, specifically relating to a self-emulsifying resin curing agent, curing system, and preparation method thereof. Background Technology

[0002] Cement slurry is injected into the annulus of the formation. After solidification, the cement slurry forms cement stone, which effectively seals the formation and provides protection and support for the casing. The quality of cementing is crucial to the safe and efficient continuation of drilling and subsequent operations such as perforation, oil and gas extraction, and well workover. Micro-cracks can easily form during these operations, leading to hazards such as inter-layer flow. Therefore, it is necessary to improve the properties of the cement stone and enhance the cement sheath's resistance to complex stresses.

[0003] Epoxy resin is a general term for compounds containing two or more epoxy groups in their molecules, which can form a three-dimensional cross-linked network of cured products in the presence of appropriate chemical reagents. It possesses excellent adhesion, corrosion resistance, and high toughness after curing. However, the use of epoxy resin in well cementing currently has the following shortcomings. First, epoxy resin is highly hydrophobic, resulting in poor dispersibility in cement slurry, affecting the performance of the slurry and cement paste. Second, due to the instability of epoxy resin emulsions, they need to be prepared fresh for use during cementing operations, affecting efficiency.

[0004] Furthermore, epoxy resin is an important thermosetting polymer, and it is well known that epoxy resin has various limitations. Without a curing agent, the desired mechanical properties cannot be obtained. The molecular structure and curing properties of the curing agent play a crucial role in the mechanical properties of the cured film. Among curing agents, small amine curing agents typically have disadvantages such as high toxicity, short gel time, strict reactant ratio requirements, excessive reactivity, and degradation in CO2. Curing agents prepared from waterborne epoxy resin and glycidyl tert-carboxylic acid esters have significantly improved the water resistance and chemical resistance of the cured film. However, their poor self-emulsifying ability severely limits their practical application.

[0005] Early methods for preparing epoxy emulsions typically employed mechanical and phase-inversion methods. These methods, involving the dispersion of water-insoluble epoxy resin in particulate form in water using high-speed stirring equipment in the presence of an emulsifier, are simple but have several drawbacks. The resulting emulsions often exhibit large particle sizes, irregular shapes, wide size distributions, and poor stability. When preparing waterborne epoxy resins using physical methods, in addition to conventional and reactive emulsifier methods, curing agent emulsification can be used for low-viscosity epoxy resins. Curing agent emulsification utilizes a substance that simultaneously emulsifies and cures epoxy resin—a self-emulsifying curing agent—to waterborneize the epoxy resin. Since epoxy resin is a thermoplastic resin, a curing agent is needed to convert it into a thermosetting resin. Curing agent emulsification combines the emulsifier and curing agent, reducing operational steps and eliminating concerns about the stability of the epoxy resin emulsion. When an emulsifier molecule contains molecular chain segments similar to those of the emulsion being emulsified, it can increase the molecular forces between the emulsifier and the emulsified material, thus making the emulsification conditions milder.

[0006] Chinese invention patent application CN101649041A discloses a method for preparing a self-emulsifying waterborne epoxy resin curing agent. The method uses triethylenetetramine and liquid epoxy resin CYD128 as raw materials, with a molar ratio of triethylenetetramine to epoxy resin CYD128 of 1-2.2:1, to synthesize an epoxy resin CYD128-TETA adduct. Then, a mixed end-capping agent is added dropwise to the epoxy resin CYD128-TETA adduct, wherein the epoxy groups in the mixed end-capping agent and the primary amine hydrogens in the epoxy resin CYD128-TETA adduct are in a stoichiometric ratio of 1:1. The secondary amine hydrogens of the end-capped product are then neutralized with an organic acid to form a salt, and finally diluted with water. However, the curing agent obtained by this method has poor self-emulsifying ability and is not suitable for resin cement.

[0007] In addition, existing technologies also suffer from the problems of brittleness of cured epoxy resin films and unsatisfactory dispersion of epoxy resin in aqueous solutions. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a self-emulsifying resin curing agent, a curing system, and a preparation method thereof. The self-emulsifying resin curing system for resin cement of this invention can resist dilution by aqueous solutions in cement slurry, forming a stable water-dispersible system. It possesses advantages such as strong corrosion resistance, high compressive strength, and low cost. The resulting resin cement can be widely used in oil and gas well cementing and leak sealing.

[0009] To achieve the above-mentioned objectives of this invention, the specific technical solution adopted by this invention is as follows:

[0010] A self-emulsifying epoxy curing agent, wherein the structural formula of the self-emulsifying epoxy curing agent is as follows:

[0011]

[0012] Preferably, the raw materials of the self-emulsifying epoxy curing agent include: epoxy resin E-44, triethylenetetramine, and 2,3-epoxypropyltrimethylammonium chloride.

[0013] Preferably, the molar ratio of triethylenetetramine to epoxy resin E-44 is 2-2.8:1; and the molar ratio of 2,3-epoxypropyltrimethylammonium chloride to triethylenetetramine is 0.5-1.2:1.

[0014] This invention also relates to a method for preparing the above-mentioned self-emulsifying epoxy curing agent, comprising the following steps:

[0015] (1) Mix epoxy resin E-44 solution with triethylenetetramine and react to obtain modified epoxy resin;

[0016] (2) Add 2,3-epoxypropyltrimethylammonium chloride to the modified epoxy resin and react to obtain the product.

[0017] Preferably, the solvent of the epoxy resin E-44 solution in step (1) is ethanol; the reaction temperature is 60-70℃ and the reaction time is 3-4h.

[0018] Preferably, the reaction temperature in step (2) is 65-75℃ and the reaction time is 2-3h.

[0019] Preferably, both steps (1) and (2) are performed in a nitrogen atmosphere.

[0020] During epoxy resin emulsification, active hydrogen is required to attack the epoxy groups and cure the resin. Active hydrogen is generally provided by amine compounds, so current emulsifying curing agents are typically epoxy-amine compounds. These amine compounds are generally polyethylenepolyamines containing multiple active hydrogens. In addition to two primary amine groups at both ends, polyethylenepolyamines also contain several secondary amine groups, providing reactive groups for subsequent crosslinking of the epoxy resin. Therefore, this invention selects a TETA-modified epoxy resin and EPTAC as the end-capping agent.

[0021] The present invention also relates to a self-emulsifying resin curing system for resin cement, wherein the self-emulsifying resin curing system comprises the above-mentioned self-emulsifying epoxy curing agent.

[0022] Preferably, the self-emulsifying resin curing system further includes epoxy resin E-44 and a cement slurry system.

[0023] Preferably, the mass ratio of the self-emulsifying curing agent to epoxy resin E-44 is 1-2:50.

[0024] Preferably, the raw materials of the cement slurry system include cement, expanding agent, water loss reducing agent, dispersant, retarder, defoamer and water.

[0025] Preferably, the amounts of the expanding agent, water loss reducing agent, dispersant, retarder and defoamer added are 1.5-2.5%, 2-3%, 0.2-0.8%, 0.5-0.9% and 0.3-0.4% of the cement mass, respectively; and the mass ratio of water to cement is 0.4-0.5:1.

[0026] This invention also relates to a method for preparing the above-mentioned self-emulsifying resin curing system, comprising the following steps:

[0027] (1) Mix the self-emulsifying curing agent with epoxy resin E-44 and stir to obtain epoxy resin emulsion;

[0028] (2) Mix the epoxy resin emulsion with the cement slurry system and stir to obtain the final product.

[0029] Preferably, the mass ratio of the epoxy resin emulsion to the cement slurry system in step (2) is 1:8-12.

[0030] Preferably, the stirring temperature in step (1) is 20-30℃, the stirring speed is 3800-4200r / min, and the stirring time is 10-20s.

[0031] Preferably, the stirring temperature in step (2) is 20-30℃, the stirring speed is 11000-13000r / min, and the stirring time is 30-40s.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The self-emulsifying resin curing system of the present invention has strong adaptability;

[0034] (2) The self-emulsifying resin curing system of the present invention requires a small amount of additive and has a simple on-site construction process;

[0035] (3) The self-emulsifying resin curing system for resin cement of the present invention has significantly improved toughness and corrosion resistance. Attached Figure Description

[0036] Figure 1 This is the infrared spectrum of the self-emulsifying epoxy curing agent prepared in Example 1. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be further described in detail below. The described embodiments are only a part of the present invention and are used to explain the present invention, but are not intended to limit the present invention. Therefore, other embodiments obtained by other people skilled in the art without creative labor are all within the protection scope of the present invention.

[0038] Epoxy resin E-44, model 6101, was purchased from Guangzhou Changhong Chemical Co., Ltd.

[0039] Jiahua Grade G cement (JHG) was purchased from Henan Qingdu Building Materials Co., Ltd.

[0040] Expanding agent, model: BS500, purchased from Henan Qingdu Building Materials Co., Ltd.;

[0041] Water loss reducer, model: BS100T, purchased from Henan Qingdu Building Materials Co., Ltd.

[0042] Dispersant, model: BS300, purchased from Henan Qingdu Building Materials Co., Ltd.;

[0043] Retarder, model: BS200R, purchased from Henan Qingdu Building Materials Co., Ltd.

[0044] Defoamer, model BP-1B, purchased from Henan Qingdu Building Materials Co., Ltd.

[0045] Unless otherwise specified, the reagents used in the following examples are all conventional reagents in the art and are commercially available.

[0046] Example 1

[0047] 1. Self-emulsifying epoxy curing agent:

[0048] Epoxy resin E-44 was dissolved in ethanol. Under nitrogen atmosphere, the epoxy resin E-44 solution was gradually added dropwise to triethylenetetramine. The addition was completed in 1 hour. The molar ratio of triethylenetetramine to epoxy resin E-44 was 2.4:1. The reaction was carried out at 60°C for 3 hours.

[0049] Then, 2,3-epoxypropyltrimethylammonium chloride was added dropwise at 65°C, with a molar ratio of 2,3-epoxypropyltrimethylammonium chloride to triethylenetetramine of 1.2:1. The reaction was carried out at 70°C for 2 hours to obtain a self-emulsifying epoxy curing agent. The infrared spectrum of this curing agent is shown below. Figure 1 As shown.

[0050] 2. Self-emulsifying resin curing system for resin cement:

[0051] A self-emulsifying curing agent and epoxy resin E-44 were mixed at a mass ratio of 1:50. The mixture was first stirred at 4000 r / min for 15 s at 25°C to obtain an epoxy resin emulsion. Then, the epoxy resin emulsion was mixed with a cement slurry system at a mass ratio of 1:8 and stirred at 12000 r / min for 35 s to obtain a self-emulsifying resin curing system for resin cement. (The cement slurry system consisted of: Jiahua G-grade cement (JHG), 2% expanding agent, 2.5% water loss reducing agent, 0.5% dispersant, 0.75% retarder, 0.375% defoamer, and water, with a water-to-cement mass ratio of 0.44.)

[0052] Example 2

[0053] 1. Self-emulsifying epoxy curing agent:

[0054] Epoxy resin E-44 was dissolved in ethanol and gradually added dropwise to triethylenetetramine under nitrogen atmosphere. The addition was completed in 1 hour. The molar ratio of triethylenetetramine to epoxy resin E-44 was 2.5:1. The reaction was carried out at 70°C for 4 hours.

[0055] Then, 2,3-epoxypropyltrimethylammonium chloride was added dropwise at 75°C, with a molar ratio of 2,3-epoxypropyltrimethylammonium chloride to triethylenetetramine of 1.3:1. The self-emulsifying epoxy curing agent was obtained by reacting at 75°C for 3 hours.

[0056] 2. Self-emulsifying resin curing system for resin cement:

[0057] A self-emulsifying curing agent and epoxy resin E-44 were mixed at a mass ratio of 1.5:50. The mixture was first stirred at 3800 r / min for 20 s at 28°C to obtain an epoxy resin emulsion. Then, the epoxy resin emulsion was mixed with a cement slurry system at a mass ratio of 1:10 and stirred at 11000 r / min for 40 s to obtain a self-emulsifying resin curing system for resin cement. (The cement slurry system consisted of: Jiahua G-grade cement (JHG), 1.5% expanding agent, 2% water loss reducing agent, 0.3% dispersant, 0.5% retarder, 0.3% defoamer, and water, with a water-to-cement mass ratio of 0.4.)

[0058] Example 3

[0059] 1. Self-emulsifying epoxy curing agent:

[0060] Epoxy resin E-44 was dissolved in ethanol and gradually added dropwise to triethylenetetramine under nitrogen atmosphere. The addition was completed in 1 hour. The molar ratio of triethylenetetramine to epoxy resin E-44 was 2.6:1. The reaction was carried out at 65°C for 4 hours.

[0061] Then, 2,3-epoxypropyltrimethylammonium chloride was added dropwise at 70°C, with a molar ratio of 2,3-epoxypropyltrimethylammonium chloride to triethylenetetramine of 1.4:1. The self-emulsifying epoxy curing agent was obtained by reacting at 70°C for 3 hours.

[0062] 2. Self-emulsifying resin curing system for resin cement:

[0063] A self-emulsifying curing agent and epoxy resin E-44 were mixed at a mass ratio of 2:50. The mixture was first stirred at 4200 r / min for 10 seconds at 30°C to obtain an epoxy resin emulsion. Then, the epoxy resin emulsion was mixed with a cement slurry system at a mass ratio of 1:12 and stirred at 13000 r / min for 30 seconds to obtain a self-emulsifying resin curing system for resin cement. (The cement slurry system consisted of: Jiahua G-grade cement (JHG), 2.5% expanding agent, 3% water loss reducing agent, 0.8% dispersant, 0.9% retarder, 0.4% defoamer, and water, with a water-to-cement mass ratio of 0.5.)

[0064] Comparative Example 1

[0065] 1. Self-emulsifying epoxy curing agent:

[0066] Epoxy resin E-44 was dissolved in ethanol. Under nitrogen atmosphere, the epoxy resin E-44 solution was gradually added dropwise to triethylenetetramine. The addition was completed in 1 hour. The molar ratio of triethylenetetramine to epoxy resin E-44 was 2.4:1. The reaction was carried out at 60°C for 3 hours.

[0067] Then, a mixed end-capping agent (a mixed solution of butyl glycidyl ether and phenyl glycidyl ether) was added dropwise at 65°C, wherein the molar ratio of butyl glycidyl ether to phenyl glycidyl ether was 1:2, and the epoxy group in the mixed end-capping agent and the primary amine hydrogen in the TETA modified epoxy resin were in a stoichiometric ratio of 1:1. The mixture was reacted at 70°C for 2 hours to obtain a self-emulsifying epoxy curing agent.

[0068] 2. The preparation method of the self-emulsifying resin curing system for resin cement is the same as in Example 1.

[0069] Comparative Example 2

[0070] 1. Self-emulsifying epoxy curing agent: Commercially available product, model: RS-610, purchased from Nanjing Qinhai Trading Co., Ltd.

[0071] 2. The preparation method of the self-emulsifying resin curing system for resin cement is the same as in Example 1.

[0072] Effect test

[0073] The evaluation of the self-emulsifying resin curing system for resin cement was conducted in accordance with standard GB / T 1771 / 2007, and the basic performance was evaluated. The test results are shown in Table 1.

[0074] Dispersion effect in water: Add the self-emulsifying resin curing agent dropwise into the aqueous solution and observe whether the self-emulsifying curing agent aggregates or settles in the aqueous solution.

[0075] Particle size testing of emulsion: The particle size of the self-emulsifying resin curing agent was tested using a laser scattering system (BI-200SM).

[0076] Compressive strength test: The resin cement with added self-emulsifying curing agent was cured in a standard rock core mold for 24 hours, and then its compressive strength was measured using a universal testing machine. The cured resin cement stone was then corroded in a CO2 high-temperature and high-pressure corrosion instrument, and its compressive strength was measured. The rate of decrease in compressive strength was then obtained.

[0077] Table 1 Performance Tests of Self-Emulsifying Resin Curing System

[0078]

[0079] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A self-emulsifying epoxy curing agent, characterized in that, The structural formula of the self-emulsifying epoxy curing agent is as follows:

2. The self-emulsifying epoxy curing agent according to claim 1, characterized in that, The raw materials of the self-emulsifying epoxy curing agent include: epoxy resin E-44, triethylenetetramine, and 2,3-epoxypropyltrimethylammonium chloride.

3. The self-emulsifying epoxy curing agent according to claim 2, characterized in that, The molar ratio of triethylenetetramine to epoxy resin E-44 is 2-2.8:1; the molar ratio of 2,3-epoxypropyltrimethylammonium chloride to triethylenetetramine is 0.5-1.2:

1.

4. A method for preparing a self-emulsifying epoxy curing agent according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix epoxy resin E-44 solution with triethylenetetramine and react to obtain modified epoxy resin; (2) Add 2,3-epoxypropyltrimethylammonium chloride to the modified epoxy resin and react to obtain the product.

5. The preparation method according to claim 4, characterized in that, The solvent for the epoxy resin E-44 solution in step (1) is ethanol; the reaction temperature is 60-70℃ and the reaction time is 3-4h.

6. The preparation method according to claim 4, characterized in that, The reaction temperature in step (2) is 65-75℃ and the reaction time is 2-3h.

7. The preparation method according to claim 4, characterized in that, Both steps (1) and (2) are performed in a nitrogen atmosphere.

8. A self-emulsifying resin curing system for resin cement, characterized in that, The self-emulsifying resin curing system includes the self-emulsifying epoxy curing agent according to any one of claims 1-3 or the self-emulsifying epoxy curing agent prepared by the preparation method according to any one of claims 4-7.

9. The self-emulsifying resin curing system for resin cement according to claim 8, characterized in that, The self-emulsifying resin curing system also includes epoxy resin E-44 and a cement slurry system.

10. The self-emulsifying resin curing system according to claim 9, characterized in that, The mass ratio of the self-emulsifying curing agent to epoxy resin E-44 is 1-2:

50.

11. The self-emulsifying resin curing system according to claim 9, characterized in that, The raw materials of the cement slurry system include cement, expanding agent, water loss reducing agent, dispersant, retarder, defoamer and water.

12. The self-emulsifying resin curing system according to claim 11, characterized in that, The amounts of the expansion agent, water loss reducer, dispersant, retarder, and defoamer added are 1.5-2.5%, 2-3%, 0.2-0.8%, 0.5-0.9%, and 0.3-0.4% of the cement mass, respectively; the mass ratio of water to cement is 0.4-0.5:

1.

13. A method for preparing the self-emulsifying resin curing system according to any one of claims 8-12, characterized in that, Includes the following steps: (1) Mix the self-emulsifying curing agent with epoxy resin E-44 and stir to obtain epoxy resin emulsion; (2) Mix the epoxy resin emulsion with the cement slurry system and stir to obtain the final product.

14. The method for preparing the self-emulsifying resin curing system according to claim 13, characterized in that, The mass ratio of epoxy resin emulsion to cement slurry system in step (2) is 1:8-12.

15. The method for preparing the self-emulsifying resin curing system according to claim 14, characterized in that, The stirring temperature in step (1) is 20-30℃, the stirring speed is 3800-4200r / min, and the stirring time is 10-20s.

16. The method for preparing the self-emulsifying resin curing system according to claim 14, characterized in that, The stirring temperature in step (2) is 20-30℃, the stirring speed is 11000-13000r / min, and the stirring time is 30-40s.

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