Main emulsifier for oil-based drilling fluid and preparation method thereof

Abstract

The present invention relates to the technical field of drilling fluids and is a primary emulsifier for oil-based drilling fluids and a preparation method thereof. The primary emulsifier for oil-based drilling fluids comprises first preparing an organic fatty acid ester and an organic fatty acid amide; then reacting the organic fatty acid ester with the organic fatty acid amide to obtain the primary emulsifier for oil-based drilling fluids. An emulsion prepared using the primary emulsifier for oil-based drilling fluids of the present invention is relatively stable before and after high-temperature hot rolling and has a high demulsification voltage. Furthermore, the rheological difference of the emulsion before and after high-temperature hot rolling is small, meeting current on-site construction requirements. Furthermore, the primary emulsifier for oil-based drilling fluids of the present invention achieves an emulsification rate of substantially 100% at room temperature and after high-temperature hot rolling.

Description

Technical Field

[0001] The invention relates to the technical field of drilling fluid, in particular to a main emulsifier for oil-based drilling fluid and a preparation method thereof. Background Art

[0002] Oil-based drilling fluids offer advantages such as high temperature resistance, strong inhibitory properties, excellent lubricity, and minimal damage to oil and gas reservoirs. The base fluid of oil-based drilling fluids is primarily a water-in-oil emulsion. The stability of this emulsion determines the performance of the drilling fluid, and the quality of the primary emulsifier plays a crucial role in emulsion stability.

[0003] Although the main emulsifiers currently used in domestic drilling fluids (such as amide emulsifiers, sulfonic acid emulsifiers, alkyl primary amine sulfonic acid emulsifiers, etc.) have developed rapidly, they also have many problems. For example, the demulsification voltage of the oil-based drilling fluid system prepared with them is greatly reduced after high-temperature hot rolling, the stability becomes poor, and the rheological properties of the system fluctuate greatly after high-temperature hot rolling, resulting in high overall production costs.

[0004] In recent years, the most widely used type of emulsifier in oil-based drilling fluids at home and abroad is amide emulsifier. Because the hydrophilic amide group and the lipophilic long carbon chain on the amide emulsifier molecules can be arranged in a direction and adsorbed on the oil-water interface, the interfacial tension of the oil-water interface is reduced, and a high-strength interfacial film is formed, which makes the emulsifier have excellent temperature resistance and emulsification properties. Among them, the more commonly used amide emulsifiers are mainly polyamide emulsifiers.

[0005] Sulfonic acid emulsifiers are designed to further improve the thermal stability of oil-based drilling fluids under high temperature conditions. This type of emulsifier generally introduces sulfonic acid groups into the emulsifier molecules. Due to the strong hydration effect of the sulfonic acid groups, the strength of the emulsifier interfacial film is improved, thereby enhancing the high temperature stability of the emulsifier.

[0006] The molecular structure of alkyl primary amine emulsifiers consists of a lipophilic group containing 8 to 12 carbon atoms and a hydrophilic amine group. By modifying the emulsifier's structure, different properties can be achieved. For example, hydrophilic groups (such as amide and amino groups) can be introduced to increase the emulsifier's hydrophilicity; hydrophobic groups can also be introduced or the hydrocarbon chain length can be increased to increase the emulsifier's lipophilicity.

[0007] Patent application publication number CN118792021A discloses a high-temperature-resistant emulsifier for oil-based drilling fluids and its preparation method. The preparation method comprises: reacting a fatty acid and an organic amine at 70-80°C to produce a first reaction system containing a first intermediate product; heating the first reaction system to 170-180°C for dehydration to produce a second reaction system containing a second intermediate product; cooling the second reaction system to 130-140°C, adding alkylbenzenesulfonic acid, and reacting to produce a third reaction system containing a third intermediate product; heating the third reaction system to 220-230°C for dehydration to produce a fourth reaction system containing a fourth intermediate product; and cooling the fourth reaction system to 70-80°C, adding an acid anhydride, and reacting to produce a liquid product. The emulsifier produced by this method has stable performance and can withstand temperatures of 260°C. The emulsifier is recyclable, helping to reduce drilling costs.

[0008] Patent application document with publication number CN106566496A discloses a high-density, low oil-water ratio emulsified drilling fluid for drilling shale horizontal wells, which is composed of the following raw materials in parts by weight: 180 parts of 3# white oil, 120 parts of 30% calcium chloride solution, 2-5 parts of a primary emulsifier, 4-8 parts of a secondary emulsifier, 12-18 parts of a reversible emulsifier, 5-10 parts of calcium oxide, 2-5 parts of organic soil, 3-8 parts of a plugging agent, 0.5-3 parts of a shearing agent, 6-12 parts of calcium carbonate, and 0-800 parts of barite. The primary emulsifier is made of tall oil fatty acid and maleic anhydride, the secondary emulsifier is made of a higher fatty acid salt and a higher fatty acid polyol ester, the reversible emulsifier is made of 9-octadecanoic acid methyl ester and hydroxyethylethylenediamine, and the shearing agent is made of styrene, methyl methacrylate, and hexadecene acrylate. The oil-water ratio is 6:4, with strong dispersion inhibition and sealing capabilities, good lubricity and temperature resistance, and can be applied to the horizontal section drilling needs of deep shale wells.

[0009] In summary, the production cost of domestic oil-based drilling fluid emulsifiers is high, the demulsification voltage drops significantly after high-temperature hot rolling, and the rheological properties are unstable. In view of this situation, a main emulsifier for oil-based drilling fluid was developed. Summary of the Invention

[0010] The present invention provides a main emulsifier for oil-based drilling fluid and a preparation method thereof, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problems of a large drop in demulsification voltage and unstable rheological properties of the existing oil-based drilling fluid emulsifier after high-temperature hot rolling.

[0011] One of the technical solutions of the present invention is achieved by the following measures: a method for preparing a primary emulsifier for oil-based drilling fluid, the entire process being carried out under a nitrogen protective atmosphere, comprising:

[0012] Organic fatty acid esters are prepared according to the following steps:

[0013] S11, heating the acidified oil under stirring;

[0014] S12, adding an organic alcohol to the acidified oil in step S11, stirring at a constant temperature, allowing the acidified oil and the organic alcohol to undergo an esterification reaction, and condensing to remove water produced during the esterification reaction to obtain an organic fatty acid ester;

[0015] Organic fatty acid amides are prepared according to the following steps:

[0016] S21, heating the acidified oil under stirring;

[0017] S22, adding ethylenediamine to the acidified oil in step S21;

[0018] S23, heating to 200° C. to 220° C. under stirring, and reacting at a constant temperature to remove water generated during the reaction;

[0019] S24, after cooling the temperature in step S23, adding anhydride;

[0020] S25, after adding the acid anhydride, raising the temperature of step S24 to 200° C. to 205° C., and performing a constant temperature reaction to obtain the organic fatty acid amide;

[0021] reacting the organic fatty acid ester with the organic fatty acid amide to obtain a primary emulsifier for oil-based drilling fluid;

[0022] Among them, the mass ratio of acidified oil, ethylenediamine and acid anhydride is 5 to 7:2 to 3:1 to 2; the mass ratio of acidified oil to organic alcohol is 6:1; and the mass ratio of organic fatty acid ester to organic fatty acid amide is 1:3.

[0023] The following are further optimizations and / or improvements to the above technical solutions:

[0024] The organic alcohol is one of 2-methyl-1,3-propanediol and glycerol; the acidified oil is one of acidified cottonseed oil and acidified soybean oil; and the acid anhydride is 2-methylenesuccinic anhydride.

[0025] Preferably, when the acidified oil is acidified cottonseed oil, the mass ratio of acidified cottonseed oil to 2-methyl-1,3-propanediol is 6:1, and the mass ratio of acidified cottonseed oil, ethylenediamine, and 2-methylenesuccinic anhydride is 5:3:2; when the acidified oil is acidified soybean oil, the mass ratio of the acidified soybean oil to glycerol is 6:1; and the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is 6:3:1.

[0026] In the above steps S11 and S21, the acidified oil is heated to 75° C. to 85° C.; in step S12, after adding the organic alcohol, the mixture is stirred at a constant temperature for 0.5 h to 1.0 h; and in step S23, the mixture is reacted at a constant temperature for 1.5 h to 3 h.

[0027] In the above step S24, the temperature of step S23 is lowered to 150° C.; in step S25, the reaction is carried out at a constant temperature for 3 hours.

[0028] The temperature of the above steps S11 and S21 is preferably 75° C.; the constant temperature stirring time of step S12 is preferably 1 hour; the constant temperature reaction temperature of step S23 is preferably 200° C., and the constant temperature reaction time is preferably 2 hours.

[0029] The reaction conditions of the organic fatty acid ester and the organic fatty acid amide are as follows: stirring at 70° C. for 1 hour.

[0030] The rotation speed involved in each of the above steps is 100 rpm to 200 rpm.

[0031] The second technical solution of the present invention is achieved by the following measures: a main emulsifier for oil-based drilling fluid prepared by the preparation method of the main emulsifier for oil-based drilling fluid according to the first technical solution.

[0032] The reaction principle of the present invention is as follows:

[0033] Heating the acidified oil first enhances its molecular activity and intensifies molecular motion. Upon addition of the organic alcohol, the carbonyl (C=O) carbon within the carboxyl (-COOH) groups of the acidified oil possesses a certain electrophilicity, while the oxygen atom within the hydroxyl (-OH) group of the organic alcohol possesses a lone electron pair, making it nucleophilic. Under heating and stirring, the oxygen atom within the hydroxyl group of the organic alcohol attacks the carbonyl carbon within the carboxyl group of the acidified oil, forming a tetrahedral intermediate. Subsequently, through proton transfer and dehydration, the water molecule is released, forming an ester bond (-COO-), yielding an organic fatty acid ester (Product A).

[0034] The two amino groups (-NH2) of ethylenediamine are highly nucleophilic and attack the carbonyl carbon of the carboxyl group of the acidified oil, undergoing a nucleophilic addition reaction and forming a positively charged intermediate. Subsequently, through proton transfer and dehydration, an amide bond (-CONH-) is formed, yielding the initial amide product. High temperatures increase the frequency and intensity of intermolecular collisions, further increasing the degree of amidation and promoting side reactions such as intramolecular and intermolecular condensation. The amino groups within the molecule undergo cyclization with the carbonyl group on the other amide bond, forming stable intermediates with five- or six-membered ring structures (i.e., amide intermediates), as well as branched alkyl-substituted amide structures. This improves the thermal and chemical stability of the organic fatty acid amide (i.e., Product B).

[0035] After the addition of the anhydride, the carbonyl carbon in the anhydride also exhibits electrophilicity and reacts with the amino group on the previously formed amide intermediate. Specifically, the amino group of the amide intermediate attacks the carbonyl carbon of the anhydride, forming a new tetrahedral intermediate. Subsequently, through proton transfer and decarboxylation, one of the carboxyl groups of the anhydride is detached as carbon dioxide, while a new acyl group (-CO-) is introduced into the amide intermediate, further modifying and improving the molecular structure of Product B, imparting it with more complex functional groups and unique interfacial activity.

[0036] Product A, a fatty acid ester, has a strong lipophilic ester group, which effectively reduces the surface tension of the oil phase, making it easier for the fatty acid ester droplets to disperse in the oil phase and forming the basic framework of a stable water-in-oil (W / O) emulsion structure. Furthermore, the long-chain fatty acid portion of Product A can form strong van der Waals forces with oil-phase molecules, enhancing its solubility and stability in the oil phase. The amide bonds and other functional groups in Product B impart certain interfacial activity and emulsifying properties, enabling it to adsorb at the oil-water interface and form a stable interfacial film. Furthermore, the molecular structure of Product B enables it to interact with other components in the drilling fluid, stably dispersing these components in the emulsion system through forces such as electrostatic adsorption, hydrogen bonding, and π-π stacking, thereby enhancing the stability of the entire drilling fluid system. Product A and Product B work together to form a denser and more stable interfacial film at the oil-water interface, effectively preventing the emulsion from breaking under high temperature conditions, increasing the breaking voltage, and also improving the rheological properties of the drilling fluid, enabling it to maintain relatively stable viscosity and fluidity under different temperature and shear conditions.

[0037] Beneficial effects of the present invention:

[0038] (1) The main emulsifier for oil-based drilling fluid of the present invention has a wide range of raw materials, is inexpensive, has a simple production process, is low in cost, and can be industrially produced.

[0039] (2) The main emulsifier for oil-based drilling fluid of the present invention forms an oil-in-water emulsion with good stability and high demulsification voltage. After high-temperature hot rolling, the emulsion is relatively stable and has a high demulsification voltage.

[0040] (3) The main emulsifier for oil-based drilling fluid of the present invention has small rheological difference of the emulsion before and after high-temperature hot rolling, stable performance, and meets the current on-site construction requirements.

[0041] (4) The main emulsifier for oil-based drilling fluid of the present invention has an emulsification rate at room temperature and an emulsification rate after high-temperature hot rolling that can basically reach 100%.

[0042] (5) The main emulsifier for oil-based drilling fluid of the present invention has a low pour point (can reach -25°C), is easy to use on site, and is less affected by temperature changes. DETAILED DESCRIPTION

[0043] The present invention is not limited to the following embodiments, and specific implementation methods can be determined based on the technical solutions of the present invention and actual conditions. The various chemical reagents and chemicals mentioned in the present invention, unless otherwise specified, are all chemical reagents and chemicals commonly known in the prior art; the percentages in the present invention, unless otherwise specified, are all percentages by mass; the solutions in the present invention, unless otherwise specified, are all aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous hydrochloric acid solution; the normal temperature and room temperature in the present invention generally refer to temperatures between 15°C and 25°C, and are generally defined as 25°C.

[0044] The acidified cottonseed oil and acidified soybean oil used in the following embodiments and examples have the following physical and chemical properties:

[0045] Acidified soybean oil:

[0046] Acid value: around 150; iodine value: around 90; melting point: 5-10°C; palmitic acid (C16): 17.4%; stearic acid (18:0): 3.2%; oleic acid (18:1): 36.7%; linoleic acid (18:2): 39.8%; others: 2.9%.

[0047] Acidified cottonseed oil:

[0048] Acid value: around 155; iodine value: around 88; melting point: 0-5°C; palmitic acid (C16): 13.1%; stearic acid (18:0): 1.9%; oleic acid (18:1): 29.8%; linoleic acid (18:2): 51.6%; others: 3.6%.

[0049] The present invention will be further described below in conjunction with various embodiments and examples:

[0050] Embodiment 1: The primary emulsifier for oil-based drilling fluid is obtained according to the following preparation method, and the entire process is carried out under a nitrogen atmosphere, comprising:

[0051] Organic fatty acid esters are prepared according to the following steps:

[0052] S11, heating the acidified oil under stirring;

[0053] S12, adding an organic alcohol to the acidified oil in step S11, stirring at a constant temperature, allowing the acidified oil and the organic alcohol to undergo an esterification reaction, and condensing to remove water produced during the esterification reaction to obtain an organic fatty acid ester;

[0054] Organic fatty acid amides are prepared according to the following steps:

[0055] S21, heating the acidified oil under stirring;

[0056] S22, adding ethylenediamine to the acidified oil in step S21;

[0057] S23, heating to 200° C. to 220° C. under stirring, and reacting at a constant temperature to remove water generated during the reaction;

[0058] S24, after cooling the temperature in step S23, adding anhydride;

[0059] S25, after adding the acid anhydride, raising the temperature of step S24 to 200° C. to 205° C., and performing a constant temperature reaction to obtain the organic fatty acid amide;

[0060] reacting the organic fatty acid ester with the organic fatty acid amide to obtain a primary emulsifier for oil-based drilling fluid;

[0061] Among them, the mass ratio of acidified oil, ethylenediamine and acid anhydride is (5 to 7): (2 to 3): (1 to 2); the mass ratio of acidified oil to organic alcohol is 6:1; and the mass ratio of organic fatty acid ester to organic fatty acid amide is 1:3.

[0062] Embodiment 2: As an optimization of the above embodiment, in step S11 and step S21, the acidified oil is heated to 75° C. to 85° C.; in step S12, after adding the organic alcohol, the mixture is stirred at a constant temperature for 0.5 h to 1.0 h; in step S23, the reaction is carried out at a constant temperature for 1.5 h to 3 h.

[0063] Implementation method 3: As an optimization of the above implementation method, in step S24, the temperature of step S23 is reduced to 150°C; in step S25, the reaction is carried out at a constant temperature for 3 hours.

[0064] Embodiment 4: As an optimization of the above embodiment, the reaction conditions of the organic fatty acid ester and the organic fatty acid amide are: stirring at a temperature of 70° C. for 1 hour.

[0065] Embodiment 5: As an optimization of the above embodiment, the temperature of steps S11 and S21 is preferably 75°C; the constant temperature stirring time of step S12 is preferably 1 hour; the constant temperature reaction temperature of step S23 is preferably 200°C, and the constant temperature reaction time is preferably 2 hours.

[0066] Embodiment 6: As an optimization of the above embodiment, the organic alcohol is one of 2-methyl-1,3-propanediol and glycerol; the acidified oil is one of acidified cottonseed oil and acidified soybean oil; and the acid anhydride is 2-methylenesuccinic anhydride.

[0067] Embodiment 7: As an optimization of the above embodiment, when the acidified oil is acidified cottonseed oil, the mass ratio of acidified cottonseed oil to 2-methyl-1,3-propanediol is 6:1, and the mass ratio of acidified cottonseed oil, ethylenediamine, and 2-methylenesuccinic anhydride is 5:3:2; when the acidified oil is acidified soybean oil, the mass ratio of the acidified soybean oil to glycerol is 6:1; the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is 6:3:1.

[0068] Implementation 8: As an optimization of the above implementation, the rotation speed involved in each step is 100 rpm to 200 rpm.

[0069] Embodiment 9: The primary emulsifier for oil-based drilling fluid is obtained according to the following preparation method, and the entire process is carried out under a nitrogen atmosphere, comprising:

[0070] Organic fatty acid esters are prepared according to the following steps:

[0071] S11, heating the acidified oil to 75° C. to 85° C. under stirring (at a speed of 100 rpm to 200 rpm);

[0072] S12, adding an organic alcohol to the acidified oil of step S11, stirring at a constant temperature for 0.5 h to 1.0 h, allowing the acidified oil and the organic alcohol to undergo an esterification reaction, and condensing and removing water produced during the esterification reaction to obtain an organic fatty acid ester;

[0073] Organic fatty acid amides are prepared according to the following steps:

[0074] S21, heating the acidified oil to 75° C. to 85° C. under stirring;

[0075] S22, adding ethylenediamine to the acidified oil in step S21;

[0076] S23, heating to 200° C. to 220° C. under stirring (rotation speed of 100 rpm to 200 rpm), and reacting at this temperature for 1.5 hours to 3 hours, and condensing and removing water generated during the reaction;

[0077] S24, after reducing the temperature in step S23 to 150° C., adding anhydride;

[0078] S25, after adding the acid anhydride, raising the temperature of step S24 to 200° C. to 205° C., and reacting at this temperature for 3 hours to obtain an organic fatty acid amide;

[0079] The organic fatty acid ester and the organic fatty acid amide are stirred at 70° C. for 1 hour to react and obtain a primary emulsifier for oil-based drilling fluid.

[0080] Embodiment 10: The primary emulsifier for oil-based drilling fluid is obtained according to the following preparation method, and the entire process is carried out under a nitrogen atmosphere, comprising:

[0081] Organic fatty acid esters are prepared according to the following steps:

[0082] S11, heating the acidified oil to 75° C. or 85° C. under stirring (at a speed of 100 rpm or 200 rpm);

[0083] S12, adding an organic alcohol to the acidified oil in step S11, stirring at a constant temperature for 0.5 h or 1.0 h, allowing the acidified oil and the organic alcohol to undergo an esterification reaction, and condensing and removing water produced during the esterification reaction to obtain an organic fatty acid ester;

[0084] Organic fatty acid amides are prepared according to the following steps:

[0085] S21, heating the acidified oil to 75° C. or 85° C. under stirring;

[0086] S22, adding ethylenediamine to the acidified oil in step S21;

[0087] S23, heating to 200° C. or 220° C. under stirring (rotation speed of 100 rpm or 200 rpm), and reacting at this temperature for 1.5 hours or 3 hours, and condensing and removing water generated during the reaction;

[0088] S24, after reducing the temperature in step S23 to 150° C., adding anhydride;

[0089] S25, after adding the acid anhydride, raising the temperature of step S24 to 200° C. or 205° C., and reacting at this temperature for 3 hours to obtain an organic fatty acid amide;

[0090] The organic fatty acid ester and the organic fatty acid amide are stirred at a temperature of 70°C for 1 hour to react to obtain a primary emulsifier for oil-based drilling fluid.

[0091] The following Examples 1 to 3 and Comparative Examples 1 to 15 are used to investigate the effects of raw material mass ratios and the like on the formation of a primary emulsifier for oil-based drilling fluids.

[0092] Comparative Example 1:

[0093] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid, comprising the following steps:

[0094] S1, preparing organic fatty acid ester (i.e., product A);

[0095] S2, preparing organic fatty acid amide (i.e., product B);

[0096] S3, stirring the product A and the product B obtained in steps S1 and S2 in a certain mass ratio and under certain conditions to obtain a main emulsifier for oil-based drilling fluid.

[0097] S11, placing a certain amount of acidified cottonseed oil into a three-necked flask, and heating to 75° C. with stirring at 100 rpm;

[0098] S12: The acidified cottonseed oil obtained in step S11 was stirred at a constant temperature of 75° C. (100 rpm), and 2-methyl-1,3-propanediol was added to a three-necked flask. The mixture was stirred at a constant temperature of 100 rpm for 1 hour, during which the water produced during the reaction was condensed and removed to obtain product A.

[0099] Wherein, in step S11 to step S12, the mass ratio of acidified cottonseed oil to 2-methyl-1,3-propanediol is 6:1.

[0100] S21, placing a certain amount of acidified cottonseed oil into a three-necked flask, and heating to 75° C. with stirring at 100 rpm;

[0101] S22, the acidified cottonseed oil obtained in S21 was stirred at 75°C (100 rpm), and ethylenediamine was added to the three-necked flask;

[0102] S23, heating the product obtained in S22 to 200° C. with stirring at 100 rpm, and reacting at this temperature for 2 h, and condensing and removing water generated during the reaction;

[0103] S24, cooling the mixture obtained in S23 to 150° C., and adding a certain amount of 2-methylenesuccinic anhydride to the container;

[0104] S25, heat the product obtained in S24 to 200°C and keep the temperature constant for 3 hours to obtain product B.

[0105] Among them, in step S21 to step S24, acidified cottonseed oil, ethylenediamine, and 2-methylenesuccinic anhydride are added in sequence according to a mass ratio of 5:3:2, and the rotation speed is maintained at 100 rpm throughout the entire process.

[0106] In step S3, the mass ratio of product A to product B is 1:2, and the mixture is stirred at a constant temperature of 70° C. at a rotation speed of 100 rpm for 1 hour to obtain a main emulsifier for oil-based drilling fluid.

[0107] Nitrogen was used throughout the above steps.

[0108] Comparative Example 2:

[0109] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of comparative example 1, except that in steps S21 to S24, the acidified cottonseed oil is replaced with acidified soybean oil.

[0110] Comparative Example 3:

[0111] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of comparative example 2, except that in steps S21 to S24, 2-methylenesuccinic anhydride is replaced with succinic anhydride.

[0112] Comparative Example 4:

[0113] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of comparative example 2, except that in steps S21 to S24, the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is changed to 6:3:1.

[0114] Comparative Example 5:

[0115] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of comparative example 4, except that in steps S21 to S24, the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is changed to 7:2:1.

[0116] Comparative Example 6:

[0117] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of comparative example 4, except that in steps S21 to S24, the acidified soybean oil is replaced with acidified cottonseed oil.

[0118] Example 1:

[0119] This embodiment is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Comparative Example 1, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0120] Comparative Example 7:

[0121] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 2, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0122] Comparative Example 8:

[0123] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 3, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0124] Example 2:

[0125] This embodiment is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Comparative Example 4, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0126] Example 3:

[0127] This embodiment is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Comparative Example 5, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0128] Comparative Example 9:

[0129] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 6, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0130] Comparative Example 10:

[0131] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 1, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0132] Comparative Example 11:

[0133] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 2, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0134] Comparative Example 12:

[0135] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 3, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0136] Comparative Example 13:

[0137] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 4, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0138] Comparative Example 14:

[0139] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 5, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0140] Comparative Example 15:

[0141] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining characteristics are the same as those of comparative example 6, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0142] The oil-based drilling fluids described in Examples 1 to 3 and Comparative Examples 1 to 15 were prepared into emulsions using a primary emulsifier, as described in Experimental Examples 1 to 18 below.

[0143] Experimental Example 1:

[0144] This experimental example is used to prepare the emulsion using the following method (standard Q / SY 17012-2024):

[0145] (1) Add 4% of the main emulsifier for oil-based drilling fluid (prepared in Comparative Example 1) to 320 mL of 0# diesel and stir at high speed for 20 minutes at a speed of 11000 rpm;

[0146] (2) Add 80 mL of 25% CaCl2 saline solution under high-speed stirring and continue stirring at high speed for 20 minutes;

[0147] (3) Add 3% CaO and 1% organic soil under high-speed stirring and stir at high speed for 20 minutes to obtain emulsion R1.

[0148] Experimental Example 2:

[0149] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for the oil-based drilling fluid is prepared from Comparative Example 2, thus obtaining emulsion R2.

[0150] Experimental Example 3:

[0151] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 3, thus obtaining emulsion R3.

[0152] Experimental Example 4:

[0153] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 4, thus obtaining emulsion R4.

[0154] Experimental Example 5:

[0155] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 5, thus obtaining emulsion R5.

[0156] Experimental Example 6:

[0157] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 6, thus obtaining emulsion R6.

[0158] Experimental Example 7:

[0159] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Example 1, thus obtaining emulsion R7.

[0160] Experimental Example 8:

[0161] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 7, thus obtaining emulsion R8.

[0162] Experimental Example 9:

[0163] This experimental example is used to prepare an emulsion. The remaining characteristics are the same as those of Comparative Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 8, thus obtaining emulsion R9.

[0164] Experimental Example 10:

[0165] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added primary emulsifier for oil-based drilling fluid is prepared from Example 2, thus obtaining emulsion R10.

[0166] Experimental Example 11:

[0167] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Example 3, thus obtaining emulsion R11.

[0168] Experimental Example 12:

[0169] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 9, thus obtaining emulsion R12.

[0170] Experimental Example 13:

[0171] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 10, thus obtaining emulsion R13.

[0172] Experimental Example 14:

[0173] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 11, thus obtaining emulsion R14.

[0174] Experimental Example 15:

[0175] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 12, thus obtaining emulsion R15.

[0176] Experimental Example 16:

[0177] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 13, thus obtaining emulsion R16.

[0178] Experimental Example 17:

[0179] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 14, thus obtaining emulsion R17.

[0180] Experimental Example 18:

[0181] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 15, thus obtaining emulsion R18.

[0182] Test example:

[0183] Emulsions R1 through R18, prepared using the above method, were subjected to performance testing before and after hot rolling. Basic properties such as rheology, demulsification voltage, and emulsification efficiency were tested for each emulsion containing the primary emulsifier for oil-based drilling fluids. The apparent viscosity (AV / mPa·s), plastic viscosity (PV / mPa·s), dynamic shear force (YP / Pa), demulsification voltage (V), and emulsification efficiency (%) of the emulsions (emulsions R1 through R18) are shown in Table 1.

[0184] The rheological stability of the emulsion can be determined by the changes in apparent viscosity and plastic viscosity before and after hot rolling. The stability of the emulsion before and after hot rolling can be determined by the decrease in demulsification voltage and emulsification efficiency before and after hot rolling.

[0185] It is well known to those skilled in the art that the smaller the change in apparent viscosity and plastic viscosity before and after hot rolling, the better the rheological stability, and vice versa.

[0186] The stability of the emulsion before and after hot rolling is considered from three aspects: the level of the demulsification voltage, the decrease in the demulsification voltage after hot rolling, and the emulsification efficiency. (1) The higher the demulsification voltage, the better the emulsion. When the demulsification voltage is not greater than 400V, the emulsion is considered to be substandard. Due to measurement errors, the demulsification voltage is not less than 450V and is considered qualified. (2) The smaller the decrease in the demulsification voltage after hot rolling, the better the emulsion. (3) An emulsification efficiency close to or equal to 100% (e.g., 99%, 98%) indicates that the emulsion is good.

[0187] It can be seen from Table 1 that, first from the demulsification voltage data, among the demulsification voltages of emulsions R1 to R6, R8, R9, R12 to R18, some have values ​​less than 450V, then the emulsions R1 to R6 (Comparative Examples 1-6), R8 (Comparative Example 7), R9 (Comparative Example 8), and R12 to R18 (Comparative Examples 9-15) are unqualified emulsions, and the main emulsifiers for oil-based drilling fluids (Comparative Examples 1-6, 7, 8, and 9-15) used to prepare the emulsions are unqualified.

[0188] From the perspective of the demulsification voltage and the decrease in the demulsification voltage after hot rolling, the demulsification voltage of emulsion R10 before hot rolling was as high as 892V, and the demulsification voltage reached 612V 72 hours after hot rolling. The demulsification voltages of emulsions R7 and R11 after 72 hours of hot rolling were 469V and 504V respectively. From the high and low demulsification voltage data, it can be seen that the demulsification voltage of emulsion R10 before and after hot rolling is higher than that of emulsion R7 and emulsion R11; subtracting the demulsification voltage before hot rolling from the demulsification voltage 16 hours after hot rolling, the decrease value of emulsion R10 is 232V, and the decrease values ​​of the demulsification voltage of emulsions R7 and R11 are 266V and 240V respectively.

[0189] As can be seen from the above, emulsion R10 (Example 2) has the best stability before and after hot rolling, followed by emulsion R11 (Example 3) and emulsion R7 (Example 1).

[0190] From the changes in apparent viscosity and plastic viscosity before and after hot rolling, the rheological properties of emulsion R10 before and after hot rolling are the best, followed by emulsion R11 and emulsion R7.

[0191] Emulsion R10 was prepared using the primary emulsifier for the oil-based drilling fluid described in Example 2. The preparation parameters described in Example 2 included:

[0192] When synthesizing product A, the mass ratio of acidified soybean oil to glycerol is 6:1; when synthesizing product B, the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is 6:3:1, and the mass ratio of product A to product B is 1:3.

[0193] The following Comparative Examples 16-18 and Examples 4-7 are used to investigate the effects of synthesis conditions on the formation of a primary emulsifier for oil-based drilling fluids.

[0194] Comparative Example 16:

[0195] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid, comprising the following steps:

[0196] S1, preparing organic fatty acid ester (i.e., product A);

[0197] S2, preparing organic fatty acid amide (i.e., product B);

[0198] S3, stirring the product A and the product B obtained in steps S1 and S2 in a certain mass ratio and under certain conditions to obtain a main emulsifier for oil-based drilling fluid.

[0199] S11, a certain amount of acidified soybean oil was placed in a three-necked flask, and heated to 70°C with stirring at 100 rpm;

[0200] S12, the acidified soybean oil obtained in step S11 was stirred at a constant temperature of 70°C (100 rpm), and 2-methyl-1,3-propanediol was added to a three-necked flask, and stirred at a constant temperature of 100 rpm for 1 hour, during which the water produced during the reaction was condensed and removed to obtain product A.

[0201] Wherein, in step S11 to step S12, the mass ratio of acidified soybean oil to 2-methyl-1,3-propanediol is 6:1.

[0202] S21, a certain amount of acidified soybean oil was placed in a three-necked flask, and heated to 70°C with stirring at 100 rpm;

[0203] S22, the acidified soybean oil obtained in S21 was stirred at 70°C (100 rpm), and ethylenediamine was added to the three-necked flask;

[0204] S23, heating the product obtained in S22 to 200° C. with stirring at 100 rpm and maintaining the temperature for 2 h, and condensing and removing water generated during the reaction;

[0205] S24, cooling the mixture obtained in S23 to 150° C., and adding a certain amount of 2-methylenesuccinic anhydride to the container;

[0206] S25, heat the product obtained in S24 to 200°C and keep the temperature constant for 3 hours to obtain product B.

[0207] In steps S21 to S24, acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride are added in sequence according to a mass ratio of 6:3:1, and the rotation speed is maintained at 100 rpm throughout the entire process.

[0208] In step S3, the mass ratio of product A to product B is 1:3, and the mixture is stirred at a constant temperature of 70° C. at a rotation speed of 100 rpm for 1 hour to obtain a main emulsifier for oil-based drilling fluid.

[0209] Nitrogen was used throughout the above steps.

[0210] Example 4:

[0211] This embodiment is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Comparative Example 16, except that in step S12, 2-methyl-1,3-propanediol is replaced with glycerol; in steps S11 to S12, the acidified oil is heated to 75°C; in step S12, the mixture is stirred at a constant temperature at 75°C; in step S21, the heating temperature is 75°C; and in step S22, the mixture is stirred at a constant temperature at 75°C.

[0212] Comparative Example 17:

[0213] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Example 4, except that the temperature in step S11 and step S21 is changed to 60°C, and the constant temperature stirring time is changed to 2 hours; the temperature in step S23 is changed to 180°C, and the constant temperature reaction time is changed to 3 hours.

[0214] Comparative Example 18:

[0215] This comparative example is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Example 4, except that the temperature in step S11 and step S21 is changed to 70°C, and the constant temperature stirring time is changed to 1.5 hours; the constant temperature reaction temperature in step S23 is changed to 180°C, and the constant temperature reaction time is changed to 4 hours.

[0216] Example 5:

[0217] This embodiment is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Example 4, except that the temperature in step S11 and step S21 is changed to 80°C, the constant temperature stirring time is changed to 0.5h, and the constant temperature reaction temperature in step S23 is changed to 210°C.

[0218] Example 6:

[0219] This embodiment is used to prepare an emulsifier for oil-based drilling fluid. The remaining features are the same as those of Example 4, except that the temperature in step S11 and step S21 is changed to 85°C; the constant temperature in step S23 is changed to 220°C, and the constant temperature reaction time is changed to 1.5h.

[0220] Example 7:

[0221] This embodiment is used to prepare a primary emulsifier for oil-based drilling fluid. The remaining features are the same as those of Example 4, except that the temperature in step S11 and step S21 is changed to 80°C; the constant temperature reaction temperature in step S23 is changed to 190°C, and the constant temperature reaction time is changed to 3 hours.

[0222] The oil-based drilling fluids described in Comparative Examples 16-18 and Examples 4-7 were prepared into emulsions using a primary emulsifier, as described in Experimental Examples 19 to 25 below.

[0223] Experimental Example 19:

[0224] This experimental example is used to prepare the emulsion using the following method (standard Q / SY 17012-2024):

[0225] (4) Add 4% of the main emulsifier for oil-based drilling fluid (prepared in Comparative Example 16) to 320 mL of 0# diesel and stir at high speed for 20 minutes at a speed of 11000 rpm;

[0226] (5) Add 80 mL of 25% CaCl2 saline solution under high-speed stirring and continue stirring at high speed for 20 minutes;

[0227] (6) Add 3% CaO and 1% organic soil under high-speed stirring and stir at high speed for 20 minutes to obtain emulsion R19.

[0228] Experimental Example 20:

[0229] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 19, except that the added main emulsifier for oil-based drilling fluid is prepared from Example 4, thus obtaining emulsion R20.

[0230] Experimental Example 21:

[0231] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 19, except that the added main emulsifier for the oil-based drilling fluid is prepared from Comparative Example 17, thus obtaining emulsion R21.

[0232] Experimental Example 22:

[0233] This experimental example is used to prepare an emulsion, and the remaining features are the same as those of Experimental Example 19, except that the added main emulsifier for oil-based drilling fluid is prepared from Comparative Example 18, thus obtaining emulsion R22.

[0234] Experimental Example 23:

[0235] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 19, except that the added main emulsifier for oil-based drilling fluid is prepared from Example 5, thus obtaining emulsion R23.

[0236] Experimental Example 24:

[0237] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 19, except that the added main emulsifier for oil-based drilling fluid is prepared from Example 6, thus obtaining emulsion R24.

[0238] Experimental Example 25:

[0239] This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 19, except that the added main emulsifier for oil-based drilling fluid is prepared from Example 7, thus obtaining emulsion R25.

[0240] Performance tests of Experimental Examples 19 to 25:

[0241] Emulsions R19 to R25, prepared using the above method, were subjected to performance testing before and after hot rolling. Basic properties such as rheology, demulsification voltage, and emulsification efficiency were tested for each of the oil-based drilling fluids containing the primary emulsifier. The results of the drilling fluids' apparent viscosity (AV / mPa·s), plastic viscosity (PV / mPa·s), dynamic shear force (YP / Pa), demulsification voltage (V), and emulsification efficiency (%) are shown in Table 2.

[0242] As can be seen from Table 2, first looking at the demulsification voltage data, among the demulsification voltages of emulsions R19, R21, and 22, some have values ​​less than 450 V. Therefore, the emulsions R19 (Comparative Example 16), R21 (Comparative Example 17), and 22 (Comparative Example 18) are unqualified emulsions, and the main emulsifiers for oil-based drilling fluids used to prepare the emulsions (Comparative Example 16, Comparative Example 17, and Comparative Example 18) are unqualified.

[0243] From the perspective of the demulsification voltage and the decrease in the demulsification voltage after hot rolling, the demulsification voltage of emulsion R20 before hot rolling is as high as 880V, and the demulsification voltage of emulsion R24 before hot rolling is as high as 885V. The demulsification voltages of emulsions R20 (Example 4) and R24 (Example 6) before hot rolling are comparable, and the decrease in the demulsification voltages of these two emulsions 16 hours before and after hot rolling is comparable. However, the decrease in the demulsification voltage of emulsion R24 72 hours before and after hot rolling is significantly greater than the decrease in the demulsification voltage of emulsion R20 72 hours before and after hot rolling. Therefore, the stability of emulsion R20 before and after hot rolling is better than that of emulsion R24.

[0244] Similarly, the stability of emulsion R20 before and after hot rolling is better than that of emulsion R23 (Example 5) and emulsion 25 (Example 7).

[0245] From the changes in apparent viscosity and plastic viscosity before and after hot rolling, the rheological properties of emulsion R20 before and after hot rolling are the best, followed by emulsions R23-25.

[0246] Emulsion R20 is prepared from the main emulsifier for oil-based drilling fluid described in Example 4. When the following raw materials and mass ratios are used in Example 4, the temperature of steps S11 and S12 is 75°C, the constant temperature stirring time of step S12 is 1 hour, the constant temperature reaction temperature of step 23 is 200°C, and the constant temperature reaction time is 2 hours.

[0247] Raw materials and mass ratio:

[0248] When synthesizing product A, the mass ratio of acidified soybean oil to glycerol is 6:1. When synthesizing product B, the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is 6:3:1, and the mass ratio of product A to product B is 1:3.

[0249] The results in Tables 1 and 2 indicate that emulsions R10 and R20 exhibit superior performance, indicating that the primary emulsifiers for oil-based drilling fluids described in Examples 2 and 4 exhibit superior emulsification. The mass ratio described in Example 2 represents the optimal mass ratio for a primary emulsifier for synthetic oil-based drilling fluids. Furthermore, synthesis conditions also affect the performance of the resulting product. Considering the overall stability of the resulting product and the principle of minimizing energy consumption, the synthesis conditions (time, temperature, etc.) of Example 4 represent the optimal synthesis path.

[0250] The corresponding relationship between Example-4, Comparative Examples 1 to 18 and Experimental Groups 1 to 25 is shown in Table 3.

[0251] The above technical features respectively constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the requirements of different situations.

[0252] Table 1 Emulsion performance test

[0253]

[0254] .

[0255] Table 2 Emulsion performance test

[0256] .

[0257] Table 3

[0258] .

Claims

1. A method for preparing a primary emulsifier for oil-based drilling fluid, characterized in that: The entire process is carried out under a nitrogen atmosphere, including: Organic fatty acid esters are prepared according to the following steps: S11, heating the acidified oil under stirring; S12, adding an organic alcohol to the acidified oil in step S11, stirring at a constant temperature, allowing the acidified oil and the organic alcohol to undergo an esterification reaction, and removing water produced during the esterification reaction to obtain an organic fatty acid ester; Organic fatty acid amides are prepared according to the following steps: S21, heating the acidified oil under stirring; S22, adding ethylenediamine to the acidified oil in step S21; S23, heating to 200° C. to 220° C. under stirring, and reacting at a constant temperature to remove water generated during the reaction; S24, after cooling the temperature in step S23, adding anhydride; S25, after adding the acid anhydride, raising the temperature of step S24 to 200° C. to 205° C., and performing a constant temperature reaction to obtain the organic fatty acid amide; The organic fatty acid ester reacts with the organic fatty acid amide to obtain a primary emulsifier for oil-based drilling fluid; The mass ratio of acidified oil, ethylenediamine and acid anhydride is 5 to 7:2 to 3:1 to 2; the mass ratio of acidified oil to organic alcohol is 6:1; the mass ratio of organic fatty acid ester to organic fatty acid amide is 1:3; The organic alcohol is one of 2-methyl-1,3-propanediol and glycerol; the acidified oil is one of acidified cottonseed oil and acidified soybean oil; the acid anhydride is 2-methylenesuccinic anhydride; When the acidified oil is acidified cottonseed oil, the mass ratio of the acidified cottonseed oil to 2-methyl-1,3-propanediol is 6:1, and the mass ratio of the acidified cottonseed oil, ethylenediamine, and 2-methylenesuccinic anhydride is 5:3:2; when the acidified oil is acidified soybean oil, the mass ratio of the acidified soybean oil to glycerol is 6:1, and the mass ratio of the acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is 6:3:1; In step S11 and step S21, the acidified oil is heated to 75° C. to 85° C.; in step S12, after adding the organic alcohol, the mixture is stirred at a constant temperature for 0.5 h to 1.0 h; in step S23, the mixture is reacted at a constant temperature for 1.5 h to 3 h; The reaction conditions of the organic fatty acid ester and the organic fatty acid amide are: stirring at a temperature of 70° C. for 1 hour.

2. The method for preparing a primary emulsifier for oil-based drilling fluid according to claim 1, wherein: The temperature of steps S11 and S21 is 75° C.; the constant temperature stirring time of step S12 is 1 hour; the constant temperature reaction temperature of step S23 is 200° C., and the constant temperature reaction time is 2 hours.

3. The method for preparing a primary emulsifier for oil-based drilling fluid according to claim 1 or 2, wherein: In step S24, the temperature of step S23 is lowered to 150° C.; or / and, in step S25, the reaction is carried out at a constant temperature for 3 hours.

4. A primary emulsifier for oil-based drilling fluid prepared according to the method for preparing a primary emulsifier for oil-based drilling fluid according to any one of claims 1 to 3.

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