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

Abstract

The invention relates to the technical field of drilling working fluid, in particular to a main emulsifier for oil-based drilling fluid and a preparation method thereof.The main emulsifier for the oil-based drilling fluid is prepared through the steps that organic fatty acid ester and organic fatty acid amide are prepared firstly; and reacting the organic fatty acid ester with organic fatty acid amide to obtain the main emulsifier for the oil-based drilling fluid. Emulsion prepared by using the main emulsifier for the oil-based drilling fluid is relatively stable before and after high-temperature hot rolling, and has relatively high demulsification voltage; the rheology difference of the emulsion before and after high-temperature hot rolling is small, and the site construction requirement at the present stage is met; in addition, according to the main emulsifier for the oil-based drilling fluid, the normal-temperature emulsification rate and the emulsification rate after high-temperature hot rolling can basically reach 100%.

Description

Technical Field

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

[0002] Oil-based drilling fluids have the advantages of high temperature resistance, strong inhibition, good lubricity, and little damage to oil and gas layers. The base fluid of the oil-based drilling fluid is mainly a water-in-oil emulsion, and the stability of the emulsion determines whether the performance of the drilling fluid is excellent. The quality of the main emulsifier of the emulsion plays a crucial role in the stability of the emulsion.

[0003] At present, although the main emulsifiers used in domestic drilling fluids (such as amide emulsifiers, sulfonic acid emulsifiers, alkyl primary amine sulfonic acid emulsifiers, etc.) have developed rapidly, there are still many problems. For example, the demulsification voltage of the oil-based drilling fluid system prepared with them decreases significantly after high-temperature thermal rolling, the stability becomes worse, and after high-temperature thermal rolling, the rheology of the system fluctuates greatly, and the overall production cost is relatively high.

[0004] In recent years, the most commonly used type of emulsifier in oil-based drilling fluids at home and abroad is amide emulsifiers. Since the hydrophilic amide group and the lipophilic long carbon chain on the amide emulsifier molecule can be oriented and adsorbed on the oil-water interface, the interfacial tension of the oil-water interface is reduced, forming a high-strength interfacial film, making the emulsifier have excellent temperature resistance and emulsifying properties. Among them, the more commonly used amide emulsifiers are mainly polyamide emulsifiers.

[0005] Sulfonic acid emulsifiers are used to further improve the thermal stability of oil-based drilling fluids under high-temperature conditions. Generally, a sulfonic acid group is introduced into the emulsifier molecule. Due to the strong hydration effect of the sulfonic acid group, the strength of the emulsifier interfacial film is improved, and thus the high-temperature stability of the emulsifier is enhanced.

[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. Different performance emulsifiers can be obtained by changing the structure of the emulsifier. For example, hydrophilic groups (such as amide groups, amino groups, etc.) can be introduced into the emulsifier to improve its hydrophilicity; hydrophobic groups can also be introduced or the length of the hydrocarbon chain can be increased to improve its lipophilicity.

[0007] The patent application document with the publication number CN118792021A discloses 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 reaction to obtain a second reaction system containing a second intermediate product; cooling the second reaction system to 130 - 140 °C, 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 reaction to obtain a fourth reaction system containing a fourth intermediate product; cooling the fourth reaction system to 70 - 80 °C, 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; this emulsifier can be recycled, which helps to reduce the drilling cost.

[0008] The patent application document with the 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 No. 3 white oil, 120 parts of 30% calcium chloride solution, 2 - 5 parts of main emulsifier, 4 - 8 parts of auxiliary emulsifier, 12 - 18 parts of reversible emulsifier, 5 - 10 parts of calcium oxide, 2 - 5 parts of organophilic clay, 3 - 8 parts of plugging agent, 0.5 - 3 parts of viscosity increasing agent, 6 - 12 parts of calcium carbonate, and 0 - 800 parts of barite. Among them, the main emulsifier is made from tall oil fatty acid and maleic anhydride, the auxiliary emulsifier is made from higher fatty acid salts and higher fatty acid polyol esters, the reversible emulsifier is made from methyl 9-octadecenoate and hydroxyethyl ethylenediamine, and the viscosity increasing agent is made from styrene, methyl methacrylate, and hexadecyl acrylate. The oil-water ratio is 6:4, which has strong inhibition and dispersion resistance and plugging ability, good lubricity, and good high-temperature resistance, and can meet the drilling requirements of the horizontal section of shale deep wells.

[0009] In summary, the production cost of oil-based drilling fluid emulsifiers in China is relatively 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 fluids was studied and invented. Summary of the Invention

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

[0011] One of the technical solutions of the present invention is achieved through the following measures: A preparation method of a main emulsifier for oil-based drilling fluids, which is carried out under a nitrogen protection atmosphere throughout the process, includes: The organic fatty acid ester is prepared according to the following steps: S11. Heat the acidified oil under stirring. S12. Add an organic alcohol to the acidified oil described in step S11, stir at a constant temperature, and let the acidified oil and the organic alcohol undergo an esterification reaction. Condense and remove the water generated during the esterification reaction to obtain an organic fatty acid ester. The organic fatty acid amide is prepared according to the following steps: S21. Heat the acidified oil under stirring. S22. Add ethylenediamine to the acidified oil in step S21. S23. Heat to 200°C to 220°C under stirring and react at a constant temperature to remove the water generated during the reaction. S24. After cooling the temperature of step S23, add an acid anhydride. S25. After adding the acid anhydride, raise the temperature of step S24 to 200°C to 205°C and react at a constant temperature to obtain the organic fatty acid amide. React the organic fatty acid ester with the organic fatty acid amide to obtain the main emulsifier for oil-based drilling fluids. Among them, the mass ratio of the acidified oil, ethylenediamine, and acid anhydride is 5 to 7: 2 to 3: 1 to 2; the mass ratio of the acidified oil to the organic alcohol is 6:1; the mass ratio of the organic fatty acid ester to the organic fatty acid amide is 1:3.

[0012] The following is a further optimization or / and improvement of the above technical solution of the invention: The above 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.

[0013] Preferably, 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; the mass ratio of the acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is 6:3:1.

[0014] 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, stir at a constant temperature for 0.5 h to 1.0 h; in step S23, react at a constant temperature for 1.5 h to 3 h.

[0015] In the above step S24, the temperature of step S23 is lowered to 150°C; in step S25, react at a constant temperature for 3 h.

[0016] The temperatures in steps S11 and S21 are preferably 75°C; the constant-temperature stirring time in step S12 is preferably 1 h; the constant-temperature reaction temperature in step S23 is preferably 200°C, and the constant-temperature reaction time is preferably 2 h.

[0017] The reaction conditions for the above-mentioned organic fatty acid ester and organic fatty acid amide are: stirring for 1 h at a temperature of 70°C.

[0018] The rotation speeds involved in the above steps are all from 100 rpm to 200 rpm.

[0019] 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 described in the first technical solution.

[0020] The reaction principle of the present invention is as follows: First, heat the acidified oil, which is beneficial to enhancing the activity of acidified oil molecules and intensifying molecular movement. After adding organic alcohol, the carbonyl (C=O) carbon in the carboxyl group (-COOH) of the acidified oil has certain electrophilicity, while the oxygen atom in the hydroxyl group (-OH) of the organic alcohol has a lone pair of electrons and shows nucleophilicity. Under the action of heating and stirring, the oxygen atom in the hydroxyl group of the organic alcohol attacks the carbonyl carbon of the carboxyl group of the acidified oil to form a tetrahedral intermediate. Subsequently, through proton transfer and dehydration processes, water molecules are removed to form an ester bond (-COO-), thereby generating an organic fatty acid ester (i.e., product A).

[0021] The two amino groups (-NH2) of ethylenediamine have strong nucleophilicity and will attack the carbonyl carbon of the carboxyl group of the acidified oil to undergo a nucleophilic addition reaction to form a positively charged intermediate. Subsequently, through proton transfer and dehydration processes, an amide bond (-CONH-) is generated to obtain a preliminary amide product. Under high-temperature conditions, the collisions between molecules are more frequent and intense, further improving the degree of amidation and promoting side reactions such as condensation within and between molecules. The amino group within the molecule reacts with the carbonyl group on another amide bond to form some stable intermediates with five- or six-membered ring structures (i.e., amide intermediates), as well as amide structures substituted by branched alkyl groups, improving the thermal stability and chemical stability of the organic fatty acid amide (i.e., product B).

[0022] After adding acid anhydride, the carbonyl carbon in the acid anhydride also has electrophilicity and will react with the amino group on the previously formed amide intermediate. Specifically, the amino group of the amide intermediate attacks the carbonyl carbon of the acid anhydride to form a new tetrahedral intermediate, and then through proton transfer and decarboxylation processes, a carboxyl group of the acid anhydride detaches in the form of carbon dioxide, and at the same time, a new acyl group (-CO-) is introduced onto the amide intermediate, further modifying and perfecting the molecular structure of product B to make it have more complex functional groups and unique interfacial activity.

[0023] As a fatty acid ester, product A has a strong lipophilicity in its ester group part, which can effectively reduce the surface tension of the oil phase, making the fatty acid ester droplets more easily dispersed in the oil phase and forming the basic framework of a stable water-in-oil (W / O) emulsion structure. At the same time, the long-chain fatty acid part of product A can also form strong van der Waals forces with the oil phase molecules, enhancing its solubility and stability in the oil phase. The amide bond and other functional groups in product B endow it with certain interfacial activity and emulsifying properties, enabling it to adsorb on the oil-water interface and form a stable interfacial film. In addition, the molecular structure of product B can enable it to interact with other components in the drilling fluid. Through electrostatic adsorption, hydrogen bonding, π-π stacking and other forces, these components are stably dispersed in the emulsion system, thereby enhancing the stability of the entire drilling fluid system. Product A and product B cooperate with each other to jointly form a denser and more stable interfacial film on the oil-water interface, effectively preventing the demulsification of the emulsion under high-temperature conditions, increasing the demulsification voltage, and at the same time improving the rheological properties of the drilling fluid, so that it can maintain relatively stable viscosity and fluidity under different temperature and shear conditions.

[0024] Advantages of the present invention: (1) For the main emulsifier for oil-based drilling fluid of the present invention, the raw materials are widely sourced, low in price, the production process is simple, the cost is low, and it can be industrially produced.

[0025] (2) For the main emulsifier for oil-based drilling fluid of the present invention, the formed water-in-oil emulsion has good stability, a high demulsification voltage, the emulsion is relatively stable after high-temperature hot rolling, and has a high demulsification voltage.

[0026] (3) For the main emulsifier for oil-based drilling fluid of the present invention, the rheological difference of the emulsion before and after high-temperature hot rolling is small, the performance is stable, and it meets the requirements of on-site construction at the present stage.

[0027] (4) For the main emulsifier for oil-based drilling fluid of the present invention, the normal-temperature emulsification rate and the emulsification rate after high-temperature hot rolling can basically reach 100%.

[0028] (5) For the main emulsifier for oil-based drilling fluid of the present invention, the pour point is low (it can reach -25°C), it is convenient to use on-site, and the influence of temperature change on it is small. Specific embodiments

[0029] The present invention is not limited by the following embodiments, and specific implementation manners can be determined according to the technical solution of the present invention and actual situations. Various chemical reagents and chemical supplies mentioned in the present invention are, unless otherwise specified, well-known and commonly used chemical reagents and chemical supplies in the prior art; the percentages in the present invention are, unless otherwise specified, mass percentages; the solutions in the present invention are, unless otherwise specified, aqueous solutions with water as the solvent. For example, a hydrochloric acid solution is an aqueous solution of hydrochloric acid; normal temperature and room temperature in the present invention generally refer to a temperature range of 15°C to 25°C, and are generally defined as 25°C.

[0030] The physicochemical properties of the acidified cottonseed oil and acidified soybean oil used in the following embodiments are as follows: Acidified soybean oil: Acid value: about 150; Iodine value: about 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%.

[0031] Acidified cottonseed oil: Acid value: about 155; Iodine value: about 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%.

[0032] The present invention will be further described below in conjunction with each embodiment and implementation manner: Embodiment 1: The main emulsifier for oil-based drilling fluid is obtained by the following preparation method, and the whole process is carried out under a nitrogen protection atmosphere, including: The organic fatty acid ester is prepared by the following steps: S11, heating the acidified oil under stirring; S12, adding an organic alcohol to the acidified oil described in step S11, stirring at a constant temperature, and the acidified oil and the organic alcohol undergo an esterification reaction. The water generated during the esterification reaction is removed by condensation to obtain an organic fatty acid ester; The organic fatty acid amide is prepared by 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 the water generated during the reaction; S24, after cooling the temperature in step S23, adding an acid anhydride; S25. After adding the acid anhydride, raise the temperature in step S24 to 200°C to 205°C and carry out a constant temperature reaction to obtain an organic fatty acid amide; React the organic fatty acid ester with the organic fatty acid amide to obtain a main emulsifier for oil-based drilling fluids; 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; the mass ratio of organic fatty acid ester to organic fatty acid amide is 1:3.

[0033] Embodiment 2: As an optimization of the above embodiment, in steps S11 and S21, heat the acidified oil to 75°C to 85°C; in step S12, after adding the organic alcohol, carry out constant temperature stirring for 0.5 h to 1.0 h; in step S23, carry out constant temperature reaction for 1.5 h to 3 h.

[0034] Embodiment 3: As an optimization of the above embodiment, in step S24, lower the temperature in step S23 to 150°C; in step S25, carry out a constant temperature reaction for 3 h.

[0035] Embodiment 4: As an optimization of the above embodiment, the reaction conditions for the organic fatty acid ester and the organic fatty acid amide are: stir at a temperature of 70°C for 1 h.

[0036] Embodiment 5: As an optimization of the above embodiment, the temperatures in steps S11 and S21 are preferably 75°C; the constant temperature stirring time in step S12 is preferably 1 h; the constant temperature reaction temperature in step S23 is preferably 200°C, and the constant temperature reaction time is preferably 2 h.

[0037] 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; the acid anhydride is 2-methylenebutanedioic anhydride.

[0038] 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-methylenebutanedioic anhydride is 5:3:2; when the acidified oil is acidified soybean oil, the mass ratio of acidified soybean oil to glycerol is 6:1; the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenebutanedioic anhydride is 6:3:1.

[0039] Embodiment 8: As an optimization of the above embodiment, the rotation speed involved in each step is 100 rpm to 200 rpm.

[0040] Embodiment 9: The main emulsifier for oil-based drilling fluids is obtained by the following preparation method, and the whole process is carried out under a nitrogen protection atmosphere, including: Organic fatty acid esters are prepared according to the following steps: S11, heating the acidified oil to 75°C to 85°C under stirring (rotation speed is 100 rpm to 200 rpm); S12, adding an organic alcohol to the acidified oil described in step S11, stirring at a constant temperature for 0.5 h to 1.0 h, and carrying out an esterification reaction between the acidified oil and the organic alcohol, and condensing and removing the water generated during the esterification reaction to obtain organic fatty acid esters; Organic fatty acid amides are prepared according to the following steps: S21, heating the acidified oil to 75°C to 85°C under stirring; S22, adding ethylenediamine to the acidified oil in step S21; S23, heating to 200°C to 220°C under stirring (rotation speed is 100 rpm to 200 rpm), and reacting at a constant temperature for 1.5 h to 3 h, and condensing and removing the water generated during the reaction; S24, after cooling the temperature of step S23 to 150°C, adding an acid anhydride; S25, after adding the acid anhydride, raising the temperature of step S24 to 200°C to 205°C, and reacting at a constant temperature for 3 h to obtain organic fatty acid amides; Stirring the organic fatty acid esters and the organic fatty acid amides at 70°C for 1 h to obtain the main emulsifier for oil-based drilling fluids by reaction.

[0041] Embodiment 10: The main emulsifier for oil-based drilling fluids is obtained according to the following preparation method, and the whole process is carried out under a nitrogen protection atmosphere, including: Organic fatty acid esters are prepared according to the following steps: S11, heating the acidified oil to 75°C or 85°C under stirring (rotation speed is 100 rpm or 200 rpm); S12, adding an organic alcohol to the acidified oil described in step S11, stirring at a constant temperature for 0.5 h or 1.0 h, and carrying out an esterification reaction between the acidified oil and the organic alcohol, and condensing and removing the water generated during the esterification reaction to obtain organic fatty acid esters; Organic fatty acid amides are prepared according to the following steps: S21, heating the acidified oil to 75°C or 85°C under stirring; S22, adding ethylenediamine to the acidified oil in step S21; S23, heating to 200°C or 220°C under stirring (rotation speed is 100 rpm or 200 rpm), and reacting at a constant temperature for 1.5 h or 3 h, and condensing and removing the water generated during the reaction; S24, after cooling the temperature of step S23 to 150°C, adding an acid anhydride; S25. After adding the acid anhydride, raise the temperature of step S24 to 200 °C or 205 °C, keep the temperature constant for 3 h to obtain the organic fatty acid amide. Stir the organic fatty acid ester and the organic fatty acid amide at 70 °C for 1 h to obtain the main emulsifier for oil-based drilling fluids by reaction.

[0042] The following Examples 1 to 3 and Comparative Examples 1 to 15 are used to investigate the effects of raw material mass ratios, etc. on the formation of the main emulsifier for oil-based drilling fluids.

[0043] Comparative Example 1: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids, and it includes the following steps: S1. Prepare the organic fatty acid ester (i.e., product A); S2. Prepare the organic fatty acid amide (i.e., product B); S3. Stir the product A and the product B obtained in steps S1 and S2 at a certain mass ratio and under certain conditions to obtain the main emulsifier for oil-based drilling fluids.

[0044] S11. Put a certain amount of acidified cottonseed oil into a three-necked flask, stir and heat it to 75 °C at a speed of 100 rpm; S12. Keep the acidified cottonseed oil obtained in step S11 stirred at a constant temperature (100 rpm) at 75 °C, add 2-methyl-1,3-propanediol to the three-necked flask, and stir at a constant speed of 100 rpm for 1 h. During this period, condense and remove the water generated during the reaction to obtain product A.

[0045] Among them, in steps S11 to S12, the mass ratio of acidified cottonseed oil to 2-methyl-1,3-propanediol is 6:1.

[0046] S21. Put a certain amount of acidified cottonseed oil into a three-necked flask, stir and heat it to 75 °C at a speed of 100 rpm; S22. Keep the acidified cottonseed oil obtained in S21 stirred at a constant temperature (100 rpm) at 75 °C, and add ethylenediamine to the three-necked flask; S23. Stir and heat the product obtained in S22 to 200 °C at a speed of 100 rpm, and keep the temperature constant for 2 h, and condense and remove the water generated during the reaction; S24. Cool the product obtained in S23 to 150 °C, and add a certain amount of 2-methylenesuccinic anhydride to the container; S25. Raise the temperature of the product obtained in S24 to 200 °C, keep the temperature constant for 3 h to obtain product B.

[0047] Among them, in steps S21 to 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 of 100 rpm is maintained throughout the process.

[0048] In step S3, the mass ratio of product A to product B is 1:2, and it is stirred at a speed of 100 rpm under constant temperature of 70°C for 1 h to obtain the main emulsifier for oil-based drilling fluid.

[0049] Nitrogen is introduced throughout the above steps.

[0050] Comparative Example 2: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid. The remaining features are the same as those in Comparative Example 1. The difference lies in that in steps S21 to S24, the acidified cottonseed oil is replaced with acidified soybean oil.

[0051] Comparative Example 3: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid. The remaining features are the same as those in Comparative Example 2. The difference lies in that in steps S21 to S24, the 2-methylenesuccinic anhydride is replaced with succinic anhydride.

[0052] Comparative Example 4: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid. The remaining features are the same as those in Comparative Example 2. The difference lies in that in steps S21 to S24, the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is changed to 6:3:1.

[0053] Comparative Example 5: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid. The remaining features are the same as those in Comparative Example 4. The difference lies in that in steps S21 to S24, the mass ratio of acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride is changed to 7:2:1.

[0054] Comparative Example 6: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid. The remaining features are the same as those in Comparative Example 4. The difference lies in that in steps S21 to S24, the acidified soybean oil is replaced with acidified cottonseed oil.

[0055] Example 1: This example is used to prepare the main emulsifier for oil-based drilling fluid. The remaining features are the same as those in Comparative Example 1. The difference lies in that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0056] Comparative Example 7: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid. The remaining features are the same as those in Comparative Example 2. The difference lies in that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0057] Comparative Example 8: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 3, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0058] Example 2: This example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 4, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0059] Example 3: This example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 5, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0060] Comparative Example 9: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 6, except that in step S3, the mass ratio of product A to product B is changed to 1:3.

[0061] Comparative Example 10: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 1, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0062] Comparative Example 11: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 2, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0063] Comparative Example 12: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 3, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0064] Comparative Example 13: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 4, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0065] Comparative Example 14: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features are the same as those in Comparative Example 5, except that in step S3, the mass ratio of product A to product B is changed to 1:4.

[0066] Comparative Example 15: This comparative example is used to prepare the main emulsifier for oil-based drilling fluids. The remaining features 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.

[0067] The main emulsifiers for oil-based drilling fluids described in Examples 1 to 3 and Comparative Examples 1 to 15 above were made into emulsions, specifically as in Experimental Examples 1 to 18 below.

[0068] Experimental Example 1: This experimental example is used to prepare an emulsion, and the method is as follows (Standard Q / SY 17012-2024): (1) Add 4% of the main emulsifier for oil-based drilling fluid (prepared from Comparative Example 1) to 320 mL of 0# diesel oil and stir at high speed for 20 min at a rotation speed of 11,000 rpm; (2) Add 80 mL of 25% CaCl2 brine solution under high-speed stirring and continue to stir at high speed for 20 min; (3) Add 3% CaO and 1% organoclay under high-speed stirring and stir at high speed for 20 min to obtain emulsion R1.

[0069] Experimental Example 2: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for oil-based drilling fluid added is prepared from Comparative Example 2, and emulsion R2 is obtained.

[0070] Experimental Example 3: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for oil-based drilling fluid added is prepared from Comparative Example 3, and emulsion R3 is obtained.

[0071] Experimental Example 4: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for oil-based drilling fluid added is prepared from Comparative Example 4, and emulsion R4 is obtained.

[0072] Experimental Example 5: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for oil-based drilling fluid added is prepared from Comparative Example 5, and emulsion R5 is obtained.

[0073] Experimental Example 6: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for oil-based drilling fluid added is prepared from Comparative Example 6, and emulsion R6 is obtained.

[0074] Experimental Example 7: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Example 1, and thus Emulsion R7 is obtained.

[0075] Experimental Example 8: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 7, and thus Emulsion R8 is obtained.

[0076] Experimental Example 9: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Comparative Mass Ratio 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 8, and thus Emulsion R9 is obtained.

[0077] Experimental Example 10: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Example 2, and thus Emulsion R10 is obtained.

[0078] Experimental Example 11: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Example 3, and thus Emulsion R11 is obtained.

[0079] Experimental Example 12: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 9, and thus Emulsion R12 is obtained.

[0080] Experimental Example 13: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 10, and thus Emulsion R13 is obtained.

[0081] Experimental Example 14: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 11, and thus Emulsion R14 is obtained.

[0082] Experimental Example 15: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 12, and thus Emulsion R15 is obtained.

[0083] Experimental Example 16: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 13, and thus Emulsion R16 is obtained.

[0084] Experimental Example 17: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 14, and thus Emulsion R17 is obtained.

[0085] Experimental Example 18: This experimental example is used to prepare an emulsion. The remaining features are the same as those of Experimental Example 1, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 15, and thus Emulsion R18 is obtained.

[0086] Test Example: According to the above method, the performances of the prepared Emulsions R1 - R18 before and after hot rolling are tested respectively. The basic performances such as rheology, demulsification voltage and emulsification efficiency of each containing the main emulsifier for the oil-based drilling fluid prepared are tested. The results of the apparent viscosity (AV / mPa·s), plastic viscosity (PV / mPa·s), yield point (YP / Pa), demulsification voltage (V), and emulsification efficiency (%) of the above emulsions (Emulsions R1 - R18) are shown in Table 1.

[0087] The rheological stability of the emulsion is known from the changes in the apparent viscosity and plastic viscosity before and after hot rolling, and the stability of the emulsion before and after hot rolling is known from the decrease amplitude of the demulsification voltage and the emulsification efficiency before and after hot rolling.

[0088] As is well known to those skilled in the art, the smaller the changes in the apparent viscosity and plastic viscosity before and after hot rolling, the better the rheological stability, and vice versa, the worse the stability.

[0089] The stability of the emulsion before and after hot rolling is considered from three aspects, namely the level of the demulsification voltage, the decrease amplitude of 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, it is considered that the emulsion does not meet the standard. Due to measurement errors, the demulsification voltage not lower than 450V is regarded as qualified. (2) The smaller the decrease amplitude of the demulsification voltage after hot rolling, the better the emulsion. (3) When the emulsification efficiency is close to or equal to 100% (such as 99%, 98%), it represents that the emulsion is better.

[0090] As can be seen from Table 1, first looking at the demulsification voltage data, among the demulsification voltages of emulsions R1 - R6, emulsion R8, emulsion R9, and emulsions R12 - R18, there are values less than 450V. Then, emulsions R1 - R6 (Comparative Examples 1 - 6), emulsion R8 (Comparative Example 7), emulsion R9 (Comparative Example 8), and emulsions R12 - R18 (Comparative Examples 9 - 15) are unqualified emulsions, and the main emulsifiers for oil - based drilling fluids used to prepare these emulsions (Comparative Examples 1 - 6, Comparative Example 7, Comparative Example 8, Comparative Examples 9 - 15) are unqualified.

[0091] Furthermore, looking at the level of the demulsification voltage and the decline amplitude of the demulsification voltage after hot rolling, the demulsification voltage of emulsion R10 before hot rolling is as high as 892V, and the demulsification voltage after hot rolling for 72h reaches 612V. The demulsification voltages of emulsions R7 and R11 after hot rolling for 72h are 469V and 504V respectively. Judging from the high and low demulsification voltage data, the demulsification voltages of emulsion R10 before and after hot rolling are higher than those of emulsions R7 and R11. Subtracting the demulsification voltage after 16h of hot rolling from the demulsification voltage before hot rolling, the decline amplitude value of emulsion R10 is 232V, and the decline amplitude values of the demulsification voltages of emulsions R7 and R11 are 266V and 240V in sequence.

[0092] As can be seen from the above, the stability of emulsion R10 (Example 2) before and after hot rolling is the best, followed by emulsions R11 (Example 3) and R7 (Example 1).

[0093] Regarding the changes in the 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 emulsions R11 and R7.

[0094] Emulsion R10 is prepared from the main emulsifier for oil - based drilling fluid described in Example 2. The preparation parameters described in Example 2 include: 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 - methylene succinic anhydride is 6:3:1, and when the mass ratio of product A to product B is 1:3.

[0095] The following Comparative Examples 16 - 18 and Examples 4 - 7 are used to investigate the influence of synthesis conditions on the formation of the main emulsifier for oil - based drilling fluid.

[0096] Comparative Example 16: This comparative example is used to prepare the main emulsifier for oil - based drilling fluid, including the following steps: S1, prepare an organic fatty acid ester (i.e., product A); S2, prepare an organic fatty acid amide (i.e., product B); S3, stir the product A and product B obtained in steps S1 and S2 at a certain mass ratio under certain conditions to obtain the main emulsifier for oil - based drilling fluid.

[0097] S11. Put a certain amount of acidified soybean oil into a three-necked flask, stir and heat it to 70 °C at a speed of 100 rpm. S12. Keep the acidified soybean oil obtained in step S11 stirred at a constant temperature (100 rpm) at 70 °C, add 2-methyl-1,3-propanediol to the three-necked flask, and stir at a constant temperature of 100 rpm for 1 h. During this period, condense and remove the water generated during the reaction to obtain product A.

[0098] Among them, in steps S11 to S12, the mass ratio of acidified soybean oil to 2-methyl-1,3-propanediol is 6:1.

[0099] S21. Put a certain amount of acidified soybean oil into a three-necked flask, stir and heat it to 70 °C at a speed of 100 rpm. S22. Keep the acidified soybean oil obtained in S21 stirred at a constant temperature (100 rpm) at 70 °C, and add ethylenediamine to the three-necked flask. S23. Stir and heat the product obtained in S22 to 200 °C at a speed of 100 rpm and keep it at a constant temperature for 2 h, and condense and remove the water generated during the reaction. S24. Cool the product obtained in S23 to 150 °C, and add a certain amount of 2-methylenesuccinic anhydride to the container. S25. Heat the product obtained in S24 to 200 °C and keep it at a constant temperature for 3 h to obtain product B.

[0100] Among them, in steps S21 to S24, acidified soybean oil, ethylenediamine, and 2-methylenesuccinic anhydride are added in sequence according to the mass ratio of 6:3:1, and the speed of 100 rpm is maintained throughout the process.

[0101] In step S3, the mass ratio of product A to product B is 1:3, and they are stirred at a constant temperature of 70 °C at a speed of 100 rpm for 1 h to obtain the main emulsifier for oil-based drilling fluids.

[0102] Nitrogen is introduced throughout the above steps.

[0103] Example 4: This example is used to prepare the main emulsifier for oil-based drilling fluids. The rest of the features are the same as those in Comparative Example 16. The difference is that in step S12, 2-methyl-1,3-propanediol is replaced by glycerol; in steps S11 to S12, the acidified oil is heated to 75 °C; in step S12, it is stirred at a constant temperature of 75 °C; in step S21, the heating temperature is 75 °C; in step S22, it is stirred at a constant temperature of 75 °C.

[0104] Comparative Example 17: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid, and the other features are the same as those in Example 4. The differences are that the temperature in Steps S11 and S21 is changed to 60 °C, and the constant-temperature stirring time is changed to 2 h; the temperature in Step S23 is changed to 180 °C, and the constant-temperature reaction time is changed to 3 h.

[0105] Comparative Example 18: This comparative example is used to prepare the main emulsifier for oil-based drilling fluid, and the other features are the same as those in Example 4. The differences are that the temperature in Steps S11 and S21 is changed to 70 °C, and the constant-temperature stirring time is changed to 1.5 h; the constant-temperature reaction temperature in Step S23 is changed to 180 °C, and the constant-temperature reaction time is changed to 4 h.

[0106] Example 5: This example is used to prepare the main emulsifier for oil-based drilling fluid, and the other features are the same as those in Example 4. The differences are that the temperature in Steps S11 and S21 is changed to 80 °C, and the constant-temperature stirring time is changed to 0.5 h; the constant-temperature reaction temperature in Step S23 is changed to 210 °C.

[0107] Example 6: This example is used to prepare the emulsifier for oil-based drilling fluid, and the other features are the same as those in Example 4. The differences are that the temperature in Steps S11 and 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 1.5 h.

[0108] Example 7: This example is used to prepare the main emulsifier for oil-based drilling fluid, and the other features are the same as those in Example 4. The differences are that the temperature in Steps S11 and 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 h.

[0109] The main emulsifiers for oil-based drilling fluid described in the above Comparative Examples 16 - 18 and Examples 4 - 7 are made into emulsions, specifically as in the following Experimental Examples 19 to 25.

[0110] Experimental Example 19: This experimental example is used to prepare an emulsion, and the method is as follows (Standard Q / SY 17012 - 2024): (4) Add 4% of the main emulsifier for oil-based drilling fluid (prepared from Comparative Example 16) to 320 mL of 0# diesel oil, and stir at high speed for 20 min, with a rotation speed of 11,000 rpm; (5) Add 80 mL of 25% CaCl₂ brine solution under high-speed stirring, and continue to stir at high speed for 20 min; (6) Add 3% CaO and 1% organic clay under high-speed stirring conditions, and stir at high speed for 20 min to obtain emulsion R19.

[0111] Experimental Example 20: This experimental example is used to prepare an emulsion. The other features are the same as those in Experimental Example 19, except that the main emulsifier for the oil-based drilling fluid added is prepared from Example 4, and emulsion R20 is obtained.

[0112] Experimental Example 21: This experimental example is used to prepare an emulsion. The other features are the same as those in Experimental Example 19, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 17, and emulsion R21 is obtained.

[0113] Experimental Example 22: This experimental example is used to prepare an emulsion. The other features are the same as those in Experimental Example 19, except that the main emulsifier for the oil-based drilling fluid added is prepared from Comparative Example 18, and emulsion R22 is obtained.

[0114] Experimental Example 23: This experimental example is used to prepare an emulsion. The other features are the same as those in Experimental Example 19, except that the main emulsifier for the oil-based drilling fluid added is prepared from Example 5, and emulsion R23 is obtained.

[0115] Experimental Example 24: This experimental example is used to prepare an emulsion. The other features are the same as those in Experimental Example 19, except that the main emulsifier for the oil-based drilling fluid added is prepared from Example 6, and emulsion R24 is obtained.

[0116] Experimental Example 25: This experimental example is used to prepare an emulsion. The other features are the same as those in Experimental Example 19, except that the main emulsifier for the oil-based drilling fluid added is prepared from Example 7, and emulsion R25 is obtained.

[0117] Performance tests of Experimental Examples 19 to 25: According to the above method, performance tests before and after heat rolling are carried out on the prepared emulsions R19 - R25. The basic properties such as rheology, demulsification voltage, and emulsification efficiency of the main emulsifiers for the prepared oil-based drilling fluids are tested. The results of the apparent viscosity (AV / mPa·s), plastic viscosity (PV / mPa·s), yield point (YP / Pa), demulsification voltage (V), and emulsification efficiency (%) of the above drilling fluids are shown in Table 2.

[0118] As can be seen from Table 2, first looking at the demulsification voltage data, among the demulsification voltages of emulsion R19, emulsion R21, and emulsion 22, there are values less than 450V. Then, the emulsion R19 (comparative example 16), emulsion R21 (comparative example 17), and emulsion 22 (comparative example 18) are unqualified emulsions, and the main emulsifiers for oil-based drilling fluids used to prepare these emulsions (comparative example 16, comparative example 17, comparative example 18) are unqualified.

[0119] Looking again at the level 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 emulsion R20 (Example 4) and emulsion R24 (Example 6) before hot rolling are comparable, and the decrease in the demulsification voltage of these two emulsions over 16h before and after hot rolling is comparable. However, the decrease in the demulsification voltage of emulsion R24 over 72h before and after hot rolling is significantly greater than that of emulsion R20 over 72h before and after hot rolling. Then, the stability of emulsion R20 before and after hot rolling is better than that of emulsion R24.

[0120] 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).

[0121] From the changes in the apparent viscosity and plastic viscosity before and after hot rolling, the rheology of emulsion R20 before and after hot rolling is the best, followed by emulsions R23 - 25.

[0122] Emulsion R20 is prepared from the main emulsifier for oil-based drilling fluid described in Example 4. When using the following raw materials and mass ratios in Example 4, the temperature in steps S11 and S12 is 75°C, the constant temperature stirring time in step S12 is 1h, the constant temperature reaction temperature in step 23 is 200°C, and the constant temperature reaction time is 2h.

[0123] Raw materials and mass ratios: 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.

[0124] From the results in Table 1 and Table 2, it can be seen that the performances of emulsion R10 and emulsion R20 are better. Then, the emulsification effects of the main emulsifiers for oil-based drilling fluids described in Example 2 and Example 4 are better, and the mass ratio described in Example 2 is the best mass ratio for synthesizing the main emulsifier for oil-based drilling fluid. In addition, the synthesis conditions will also affect the performance of the synthesized product. Considering the comprehensive stability of the synthesized product and the principle of the lowest energy consumption, the synthesis conditions (time, temperature, etc.) in Example 4 are the optimal synthesis route.

[0125] The corresponding relationships between Example - 4, Comparative Examples 1 to 18, and Experimental Groups 1 - 25 are shown in Table 3.

[0126] The above technical features respectively constitute the embodiments of the present invention, which have strong adaptability and implementation effects. Non-essential technical features can be increased or decreased according to actual needs to meet the requirements of different situations.

[0127] Table 1 Emulsion Performance Measurement Experiment 。

[0128] Table 2 Emulsion Performance Measurement Experiment 。

[0129] Table 3 。

Claims

1. A preparation method of a main emulsifier for oil-based drilling fluid, characterized in that, The whole process is carried out under a nitrogen protection atmosphere and includes: The organic fatty acid ester is prepared according to the following steps: S11, heating the acidified oil under stirring; S12, adding an organic alcohol to the acidified oil described in step S11, stirring at a constant temperature, and carrying out an esterification reaction between the acidified oil and the organic alcohol to remove the water generated during the esterification reaction, thereby obtaining the organic fatty acid ester; The organic fatty acid amide is 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 the water generated during the reaction; S24, after cooling the temperature of step S23, adding an acid anhydride; S25, after adding the acid anhydride, raising the temperature of step S24 to 200°C to 205°C and reacting at a constant temperature to obtain the organic fatty acid amide; The organic fatty acid ester reacts with the organic fatty acid amide to obtain the main emulsifier for oil-based drilling fluids; Among them, the mass ratio of the acidified oil, ethylenediamine, and acid anhydride is 5 to 7: 2 to 3: 1 to 2; the mass ratio of the acidified oil to the organic alcohol is 6:1; the mass ratio of the organic fatty acid ester to the organic fatty acid amide is 1:

3.

2. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 1, characterized in that, 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.

3. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 2, characterized in that, 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.

4. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 1 or 2 or 3, characterized in that, In steps S11 and S21, the acidified oil is heated to 75°C to 85°C; in step S12, after adding the organic alcohol, stirring is carried out 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.

5. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 4, characterized in that, The temperature in steps S11 and S21 is preferably 75°C; the constant stirring time in step S12 is preferably 1 h; the constant reaction temperature in step S23 is preferably 200°C, and the constant reaction time is preferably 2 h.

6. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 1 or 2 or 3, characterized in that, In step S24, the temperature of step S23 is reduced to 150°C; and / or, in step S25, the reaction is carried out at a constant temperature for 3 h.

7. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 4, characterized in that, In step S24, the temperature of step S23 is reduced to 150°C; and / or, in step S25, the reaction is carried out at a constant temperature for 3 h.

8. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 5, characterized in that, In step S24, the temperature of step S23 is reduced to 150°C; and / or, in step S25, the reaction is carried out at a constant temperature for 3 h.

9. The preparation method of the main emulsifier for oil-based drilling fluid according to claim 8, characterized in that, The reaction conditions for the organic fatty acid ester and the organic fatty acid amide are: stirring at a temperature of 70°C for 1 h.

10. A main emulsifier for oil-based drilling fluids prepared by the preparation method of the main emulsifier for oil-based drilling fluids according to any one of claims 1 to 9.

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