High-Temperature Resistant Emulsifiers for Oil-Based Drilling Fluids and Their Preparation Methods

Abstract

This invention relates to the field of drilling technology, and more particularly to a high-temperature resistant emulsifier for oil-based drilling fluids and its preparation method. The preparation method includes: reacting fatty acids and organic amines at 70-80°C to obtain a first reaction system containing a first intermediate product; heating the first reaction system to 170-180°C for dehydration to obtain a second reaction system containing a second intermediate product; cooling the second reaction system to 130-140°C and adding alkylbenzene sulfonic acid for reaction to obtain a third reaction system containing a third intermediate product; heating the third reaction system to 220-230°C for dehydration to obtain a fourth reaction system containing a fourth intermediate product; cooling the fourth reaction system to 70-80°C and adding acid anhydride for reaction to obtain a liquid product. The emulsifier prepared by this method has stable performance and can withstand high temperatures up to 260°C; the emulsifier is recyclable, which helps reduce drilling costs.

Description

Technical Field

[0001] This invention relates to the field of drilling technology, and in particular to a high-temperature resistant emulsifier for oil-based drilling fluids and its preparation method. Background Technology

[0002] With the increasing number of deep wells, ultra-deep wells, and shale gas wells being developed worldwide, research on oil-based drilling fluid technology has become increasingly mature, and emulsifier technology, as a major additive in oil-based drilling fluids, has also developed rapidly. Domestic and international experts and scholars have conducted in-depth research on the chemical stability, high-temperature resistance, inhibition properties, anti-pollution ability, and protection of oil and gas reservoirs of emulsifiers, achieving certain results. The role of oil-based drilling fluid emulsifiers is to: directionally adsorb onto the oil-water interface to form a strong interfacial film, reduce interfacial tension, and prevent the aqueous phase dispersed in the oil from agglomerating into large droplets. Emulsifiers stabilize the emulsion, allowing oleophilic colloidal substances such as organic clays, filtration reducers, and plugging agents to form a network structure with a certain strength at the interface. Under high temperature conditions, the activity of emulsifier molecules increases, and the linkage bonds (ether bonds, ROR) with smaller bond energy in the emulsifier molecules are easily broken, which reduces the intermolecular interaction force and disrupts the hydrogen bonding effect, causing the emulsifier to lose its emulsifying ability, and even the emulsion wave to break down, making it impossible to float barite, which greatly increases the risk of drilling accidents. The performance of emulsifiers plays a decisive role in the stability of oil-based drilling fluids.

[0003] Currently, oil-based temperature-resistant emulsifiers are classified into the following three categories:

[0004] 1. Sulfonic acid emulsifiers for oil-based drilling fluids

[0005] The oil-based drilling fluid emulsifier contains sulfonic acid groups, which have strong hydration capabilities and enable the emulsifier to withstand high temperatures. A bis(benzene) sulfonate gemini surfactant is synthesized through etherification, sulfonation, and neutralization reactions. This emulsifier exhibits excellent emulsifying and salt-resistant properties, improving emulsion stability and minimizing pH impact. Oil-based drilling fluids formulated with this emulsifier have a demulsification voltage exceeding 1000V, strong salt and drill fouling resistance, good rheological properties, a dynamic ratio of 0.42, high rock-carrying efficiency, and can withstand temperatures up to 200℃. It has already been applied in the Xinjiang Oilfield.

[0006] 2. Carboxylic acid emulsifiers for oil-based drilling fluids

[0007] Long-chain tamarinic acid molecules contain tamarinic acid groups, which have strong hydrophilicity and are a type of high-temperature resistant emulsifier. Due to its "rod-like" structure rather than a "comb-like" structure, its emulsifying performance is poor, and it is often improved through chemical modification.

[0008] 3. Amide emulsifiers for oil-based drilling fluids

[0009] Because the hydrophilic amide groups and lipophilic long carbon chains on amine emulsifier molecules can be directionally aligned and adsorbed at the oil-water interface, the interfacial tension at the oil-water interface is reduced, forming a high-strength interfacial film, which gives the emulsifier excellent temperature resistance and emulsifying properties. Among the more commonly used amide emulsifiers, polyamide emulsifiers are the most prevalent.

[0010] Currently, the temperature resistance of domestically produced emulsifiers is generally around 220℃, which is insufficient to meet the requirements of high-temperature drilling operations in deep and ultra-deep wells. Therefore, there is an urgent need to develop a new type of high-temperature resistant emulsifier to improve the stability and temperature resistance of drilling fluids, thereby ensuring the efficiency and safety of deep and ultra-deep well operations. Summary of the Invention

[0011] To address or partially address the problems existing in related technologies, this invention provides a high-temperature resistant emulsifier for oil-based drilling fluids and its preparation method.

[0012] This invention provides a method for preparing a high-temperature resistant emulsifier for oil-based drilling fluids, comprising:

[0013] Step a) Fatty acids and organic amines are reacted at 70–80°C to obtain a first reaction system containing a first intermediate product; the organic amine includes compounds represented by Formula I, where n ≥ 3;

[0014]

[0015] Step b) The first reaction system is heated to 170-180°C to carry out a dehydration reaction, and a second reaction system containing the second intermediate product is obtained.

[0016] Step c) Cool the second reaction system to 130-140°C, add alkylbenzene sulfonic acid to react, and obtain a third reaction system containing a third intermediate product;

[0017] Step d) The third reaction system is heated to 220-230°C to carry out a dehydration reaction, and a fourth reaction system containing a fourth intermediate product is obtained.

[0018] Step e) Cool the fourth reaction system to 70-80°C, add acid anhydride to react, and obtain a liquid product, which is the high-temperature resistant emulsifier for oil-based drilling fluid.

[0019] Furthermore, the compound represented by Formula I is specifically tetraethylenepentamine, pentaethylenehexamine, or hexaethyleneheptaamine.

[0020] Furthermore, the organic amine also includes N,N'-dihydroxyethylethylenediamine and / or hydroxyethylethylenediamine.

[0021] Furthermore, the fatty acid is selected from one or both of tall oil fatty acids and lauric acid.

[0022] Furthermore, the alkylbenzene sulfonic acid is selected from one or two of dodecylbenzene sulfonic acid, tetradecylbenzene sulfonic acid, and hexadecylbenzene sulfonic acid.

[0023] Furthermore, the acid anhydride is selected from one or both of maleic anhydride and phthalic anhydride.

[0024] Further, step e) specifically involves: cooling the fourth reaction system to 70-80°C, adding acid anhydride and dispersant to react and obtain a liquid product, which is an anti-high temperature emulsifier for oil-based drilling fluid.

[0025] Furthermore, the ratio of fatty acid, organic amine, benzenesulfonic acid, and acid anhydride is (15-25):(15-25):(15-25):(5-10):(20-40).

[0026] Furthermore, the reaction time for step a) is 1-3 hours, the reaction time for step b) is 3-4 hours, the reaction time for step c) is 1-3 hours, the reaction time for step d) is 4-6 hours, and the reaction time for step e) is 7-9 hours.

[0027] The present invention also provides a high-temperature resistant emulsifier for oil-based drilling fluids, which is prepared according to any one of the methods described above.

[0028] The high-temperature resistant emulsifier for oil-based drilling fluids and its preparation method provided by this invention may have the following beneficial effects:

[0029] This preparation method uses fatty acids, ethylenediamine condensation products, and alkylbenzene sulfonic acid as raw materials to obtain an emulsifier with excellent temperature resistance by controlling the reaction conditions. The emulsifier has stable performance and can withstand high temperatures of 260℃, which improves the research and development effect of high-temperature and high-density oil-based drilling fluids and provides technical support for deep and ultra-deep wells. The emulsifier can be recycled, which helps to reduce drilling costs.

[0030] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0031] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0032] Figure 1 This is a photograph of the high-temperature, high-pressure filter cake after drilling fluid hot rolling aging for 16 hours in Example 1;

[0033] Figure 2This is a photograph of the high-temperature, high-pressure filter cake after 72 hours of hot rolling aging of drilling fluid in Example 1.

[0034] Figure 3 This is a picture of the high-temperature and high-pressure filter cake after drilling fluid hot rolling aging for 16 hours in Example 2;

[0035] Figure 4 This is a picture of the high-temperature and high-pressure filter cake after 72 hours of hot rolling aging of drilling fluid in Example 2. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0038] It should be understood that although the terms "first," "second," "third," etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this invention, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0039] This invention provides a method for preparing a high-temperature resistant emulsifier for oil-based drilling fluids, comprising:

[0040] Step a) Fatty acids and organic amines are reacted at 70–80°C to obtain a first reaction system containing a first intermediate product; the organic amine includes compounds represented by Formula I, where n ≥ 3;

[0041]

[0042] Step b) The first reaction system is heated to 170-180°C to carry out a dehydration reaction, and a second reaction system containing the second intermediate product is obtained.

[0043] Step c) Cool the second reaction system to 130-140°C, add alkylbenzene sulfonic acid to react, and obtain a third reaction system containing a third intermediate product;

[0044] Step d) The third reaction system is heated to 220-230°C to carry out a dehydration reaction, and a fourth reaction system containing a fourth intermediate product is obtained.

[0045] Step e) Cool the fourth reaction system to 70-80°C, add acid anhydride to react, and obtain a liquid product, which is the high-temperature resistant emulsifier for oil-based drilling fluid.

[0046] To improve the temperature resistance of emulsifiers, the inventors of this application considered designing compounds containing imidazoline and sulfonamide structures. Specifically, imidazoline surfactants possess good thermal stability, chemical stability, and biodegradability, which allow them to maintain effective emulsifying performance at high temperatures. The nitrogen atom in the imidazoline structure can form a coordinate bond, combining with metal ions, which helps enhance its stability at high temperatures. Therefore, emulsifiers containing imidazoline structures can effectively reduce emulsion demulsification and oil-water separation in high-temperature drilling operations. Sulfonamides are a class of compounds containing sulfonic acid and amide groups. Because the sulfonic acid group is a strongly hydrophilic group, it can enhance the solubility of the emulsifier in the aqueous phase, while the amide group can provide certain thermal and chemical stability. This structural characteristic allows sulfonamide emulsifiers to maintain good emulsifying stability under high-temperature conditions, reducing the decline in emulsion performance caused by temperature increases. The applicant further discovered that emulsifiers including compounds with imidazoline and sulfonamide structures have improved temperature resistance, but the improvement is not ideal.

[0047] To further improve temperature resistance, the inventors of this application discovered that when the imidazoline structure and the sulfonamide structure are linked on a single molecular chain, and there are two imidazoline structures located at both ends of the molecular chain, the temperature resistance of the emulsifier is significantly improved. Therefore, the inventors of this application first considered synthesizing a compound whose molecular chain contains both imidazoline and sulfonamide structures as an emulsifier. To achieve this desired effect, this application uses fatty acids and organic amines as raw materials. The organic amines include the condensation product of the compound shown in Formula I, hereinafter referred to as ethylenediamine. The condensation product of ethylenediamine is used to form an imidazoline structure after amidation and dehydration. The secondary amine group of the ethylenediamine condensation product reacts with the sulfonic acid group to form a sulfonamide structure. Steps a) to d) above are steps for synthesizing an emulsifier containing the above-mentioned compound.

[0048] Step a) above involves the reaction of the carboxyl group of the fatty acid with the secondary amine groups at both ends of the condensation product of ethylenediamine to form a first intermediate product, which includes an ammonium salt of an organic acid. Step b) involves a dehydration reaction after heating, during which the ammonium salt of the organic acid undergoes a ring-closure reaction to form an imidazoline structure, meaning the second intermediate product includes an imidazoline compound. Specifically, the second intermediate product has imidazoline structures at both ends, and since the n ≥ 3 of the condensation product of ethylenediamine, the second intermediate product formed by the dehydration reaction also contains unreacted secondary amine groups. Step c) involves the reaction of the secondary amine group of the second intermediate product with alkylbenzene sulfonic acid to form an organic sulfonate, meaning the third intermediate product includes an organic sulfonate. Step d) involves the dehydration of the organic sulfonate to generate a sulfonamide, thereby producing a bisimidazoline sulfonamide organic compound containing imidazoline structures at both ends and a sulfonamide structure in the middle. The reaction temperature has a significant impact on the smooth progress of the above reactions. In this embodiment, the reaction temperature for step a) is controlled at 70–80°C, the reaction temperature for step b) at 170–180°C, the reaction temperature for step c) at 130–140°C, and the reaction temperature for step d) at 220–230°C. More preferably, the reaction temperature for step a) is 75°C, the reaction temperature for step b) is 175°C, the reaction temperature for step c) is 135°C, and the reaction temperature for step d) is 225°C. The reaction time for step a) is preferably 1–3 h, the reaction time for step b) is preferably 3–4 h, the reaction time for step c) is preferably 1–3 h, and the reaction time for step d) is preferably 4–6 h. More preferably, the reaction time for step a) is 2 h; the reaction time for step b) is 4 h; the reaction time for c) is 2 h; and the reaction time for d) is 5 h.

[0049] The preferred ratio of the fatty acid, organic amine, and benzenesulfonic acid is (15-25):(15-25):(15-25), more preferably 1:1:1. The fatty acid is preferably selected from tall oil fatty acid and lauric acid, or one or both, more preferably tall oil fatty acid. The condensation product of ethylenediamine is preferably tetraethylenepentamine, pentaethylenehexamine, or hexaethyleneheptaamine, more preferably tetraethylenepentamine, as the emulsifier prepared using tetraethylenepentamine has the most suitable viscosity. In addition to containing the condensation product of ethylenediamine, the organic amine preferably includes N,N'-dihydroxyethylethylenediamine and / or hydroxyethylethylenediamine. These two compounds can react with the fatty acid in steps a) and b) above to form a monoimidazoline organic compound containing an imidazoline structure, thereby further improving the temperature resistance of the emulsifier. The alkylbenzenesulfonic acid is preferably selected from one or two of dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, and hexadecylbenzenesulfonic acid, more preferably dodecylbenzenesulfonic acid.

[0050] During steps a) to d), maintain negative pressure inside the reactor and promptly remove the generated water. After steps a) to d), you will obtain either a bisimidazoline sulfonamide organic compound or a combination of a bisimidazoline sulfonamide organic compound and a monoimidazoline organic compound.

[0051] Subsequently, the inventors discovered that although the emulsifier obtained by this method had good temperature resistance, it also had strong wettability, affecting the viscosity of the formulated system. To solve this problem, this application continued its research and found that this might be due to the presence of a large number of amine groups in the emulsifier system. Therefore, acid anhydrides were added to the reaction system to treat the incompletely reacted amine groups, forming an amide, i.e., step e) above. This not only removed the amine groups but also created an amide that had an emulsifying effect. The reaction temperature in step e) was controlled at 70–80°C, and the reaction time was preferably 7–9 hours, more preferably 8 hours. After the reaction, a liquid product was obtained, which is the high-temperature resistant emulsifier for oil-based drilling fluids. In addition, the above steps a) to e) were carried out under stirring conditions, which helped to increase the contact area of ​​the reactants, accelerate the reaction rate, and also helped to distribute heat evenly, thus making it easier to control the reaction temperature.

[0052] The aforementioned acid anhydride is preferably selected from one or two of maleic anhydride and phthalic anhydride. This step also preferably involves adding a dispersant, preferably selected from one or two of diethylene glycol monobutyl ether, white oil, and isopropanol, with diethylene glycol monobutyl ether being more preferred. Step e) specifically involves cooling the fourth reaction system to 70–80°C, adding the acid anhydride and dispersant to react, and obtaining a liquid product, which is the high-temperature resistant emulsifier for oil-based drilling fluids. Those skilled in the art will understand that the dispersant does not participate in the reaction and only serves a dilution function. The preferred ratio of the above-mentioned fatty acid, organic amine, benzenesulfonic acid, acid anhydride, and dispersant is (15–25):(15–25):(15–25):(5–10):(20–40), more preferably 20:20:20:8:32.

[0053] Another embodiment of the present invention provides a high-temperature resistant emulsifier for oil-based drilling fluids, which is prepared according to the method of the above embodiment.

[0054] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0055] Example 1

[0056] Add 20 parts tall oil fatty acid to the reactor, start stirring, then add 10 parts hydroxyethyl ethylenediamine and 10 parts tetraethylenepentamine. React at 70-80℃ for 2 hours, then raise the temperature to 170-180℃ and react for 4 hours. Lower the temperature to 130-140℃ and add 20 parts dodecylbenzenesulfonic acid, reacting for 2 hours. Then raise the temperature to 220-230℃ and react for 4-6 hours, lowering the temperature to 70-80℃. Maintain negative pressure inside the reactor during the reaction, and promptly remove any water generated.

[0057] Eight parts of maleic anhydride and 32 parts of diethylene glycol monobutyl ether were added to a reaction vessel. The reaction product was then sealed and subjected to graft copolymerization at 70-80℃ for 8 hours to obtain a liquid product, which is the high-temperature resistant emulsifier for oil-based drilling fluids.

[0058] The prepared high-temperature resistant emulsifier was evaluated using single-agent testing according to the standard Q / CPBCD0004-2023. The evaluation results are listed in Table 1.

[0059] Table 1 Evaluation of Single-Agent Testing

[0060]

[0061] The application of the prepared high-temperature resistant emulsifier in a drilling fluid system was evaluated. The drilling fluid system consisted of: 270 ml diesel oil + 4% of the high-temperature resistant emulsifier described in this application + 2% fatty acid amide + 30 ml brine + 8% oil-based filtration reducer + 5% calcium oxide + 3% organic clay + 2% plugging agent + 6% fine calcium + 140 g ultrafine barite + 200 g barite (density: 1.7 g / cm³). 3 ).

[0062] Experimental conditions: Hot rolling conditions: 260℃; HTHP temperature: 180℃

[0063] Experimental image: High-temperature and high-pressure filter cake after 16 hours of hot rolling aging. Figure 1 As shown, the high-temperature, high-pressure filter cake aged for 72 hours by hot rolling is as follows: Figure 2 As shown;

[0064] Evaluation standard: GB / T / 16783.2-2012

[0065] The evaluation results are listed in Table 2:

[0066] Table 2 Evaluation of Drilling Fluid Systems

[0067]

[0068] Experimental conditions: Aging temperature: 260℃; Rheological test temperature: 65℃; HTHP test temperature: 180℃

[0069] From Table 1-2, and Figure 1-2 It can be seen that the system has good rheological properties after aging, with a demulsification voltage of over 800V, a water loss of less than 5mL under high temperature and high pressure, and a thin and tough mud cake, indicating that the system has good resistance to high temperature emulsification.

[0070] Example 2

[0071] Add 20 parts tall oil fatty acid to the reactor, start stirring, then add 20 parts tetraethylenepentamine, react at 70-80℃ for 2 hours, raise the temperature to 170-180℃ and react for 4 hours, lower the temperature to 130-140℃ and add 20 parts dodecylbenzenesulfonic acid, react for 2 hours, then raise the temperature to 220-230℃ and react for 4-6 hours, then lower the temperature to 70-80℃. Maintain negative pressure inside the reactor during the reaction, and promptly remove the generated water.

[0072] Eight parts of maleic anhydride and 32 parts of diethylene glycol monobutyl ether were added to a reaction vessel. The reaction product was then subjected to graft copolymerization at 70-80°C for 8 hours in a sealed container. The resulting liquid product is the oil-based high-temperature emulsifier of this application.

[0073] The prepared high-temperature resistant emulsifier was evaluated using single-agent testing, and the evaluation results are listed in Table 3:

[0074] Table 3 Evaluation of Single-Agent Testing

[0075]

[0076] The application of the prepared high-temperature resistant emulsifier in drilling fluid systems was evaluated. The drilling fluid system is as follows:

[0077] 1#: 270mL 3# white oil + 4% emulsifier (as per this application) + 2% fatty acid amide + 30mL brine + 2% sealing agent + 3% organic clay + 8% calcium oxide + 4% fine calcium (5000 mesh) + 6% filtration loss reducer + 340g barite (density: 1.7g / cm³) 3 )

[0078] 2#: 270mL 3# white oil + 4% emulsifier (as per this application) + 2% fatty acid amide + 30mL brine + 2% sealing agent + 3% organic clay + 8% calcium oxide + 4% fine calcium (5000 mesh) + 6% filtration loss reducer + 680g barite (density: 2.0g / cm³) 3 )

[0079] Experimental conditions: Hot rolling conditions: 260℃; HTHP temperature: 180℃

[0080] Evaluation standard: GB / T / 16783.2-2012

[0081] Experimental image: High-temperature and high-pressure filter cake after 16 hours of hot rolling aging. Figure 3 As shown, the high-temperature, high-pressure filter cake aged for 72 hours by hot rolling is as follows: Figure 4 As shown;

[0082] The evaluation results are listed in Table 4:

[0083] Table 4 Evaluation of Drilling Fluid Systems

[0084]

[0085] Experimental conditions: Aging temperature: 260℃; Rheological test temperature: 65℃; HTHP test temperature: 180℃

[0086] From Table 3-4, and Figure 3-4 It can be seen that the system has good rheological properties after aging, with a demulsification voltage of over 800V, a water loss of less than 5mL under high temperature and high pressure, and a thin and tough mud cake, indicating that the system has good resistance to high temperature emulsification.

[0087] As can be seen from the above, the high-temperature resistant emulsifier for oil-based drilling fluids and its preparation method have the following advantages:

[0088] This preparation method uses fatty acids, ethylenediamine condensation products, and alkylbenzene sulfonic acid as raw materials to obtain an emulsifier with excellent temperature resistance by controlling the reaction conditions. The emulsifier has stable performance and can withstand high temperatures of 260℃, which improves the research and development effect of high-temperature and high-density oil-based drilling fluids and provides technical support for deep and ultra-deep wells. The emulsifier can be recycled, which helps to reduce drilling costs.

[0089] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a high-temperature resistant emulsifier for oil-based drilling fluids, characterized in that, include: Step a) Fatty acids and organic amines react at 70-80°C to obtain a first reaction system containing a first intermediate product, wherein the fatty acids are selected from tall oil fatty acids and lauric acid, or one or two of them, and the organic amines include tetraethylenepentamine, pentaethylenehexamine or hexaethyleneheptaamine. Step b) The first reaction system is heated to 170~180℃ to carry out a dehydration reaction to obtain a second reaction system containing the second intermediate product; Step c) Cool the second reaction system to 130~140℃, add alkylbenzene sulfonic acid to react, and obtain a third reaction system containing a third intermediate product, wherein the alkylbenzene sulfonic acid is selected from one or two of dodecylbenzene sulfonic acid, tetradecylbenzene sulfonic acid and hexadecylbenzene sulfonic acid. Step d) The third reaction system is heated to 220~230℃ to carry out a dehydration reaction, and a fourth reaction system containing a fourth intermediate product is obtained. Step e) Cool the fourth reaction system to 70-80°C, add acid anhydride and dispersant to react, and obtain a liquid product, which is the high-temperature resistant emulsifier for oil-based drilling fluids. The acid anhydride is selected from one or both of maleic anhydride and phthalic anhydride. The ratio of fatty acid, organic amine, alkylbenzene sulfonic acid, acid anhydride and dispersant is (15~25):(15~25):(15~25):(5~10):(20~40).

2. The preparation method according to claim 1, characterized in that, The organic amine also includes N,N'-dihydroxyethylethylenediamine and / or hydroxyethylethylenediamine.

3. The preparation method according to claim 1, characterized in that, The reaction time for step a) is 1-3 hours, the reaction time for step b) is 3-4 hours, the reaction time for step c) is 1-3 hours, the reaction time for step d) is 4-6 hours, and the reaction time for step e) is 7-9 hours.

4. A high-temperature resistant emulsifier for oil-based drilling fluids, characterized in that, It is prepared according to the method described in any one of claims 1 to 3.

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