Emulsifier, preparation method thereof and oil-based drilling fluid

Abstract

The invention relates to the technical field of emulsifiers, and discloses an emulsifier, a preparation method thereof and an oil-based drilling fluid, the emulsifier has a polyene polyamine skeleton and a hydrophobic group connected to the skeleton, and part of the polyene polyamine skeleton is connected with a sulfonic acid group; wherein the molar ratio of the sulfur element to the nitrogen element in the emulsifier is (0.02-0.4): 1. According to the emulsifier provided by the invention, the part of the emulsifier without the sulfonic acid group can play a role of a main emulsifier, the part of the emulsifier containing the sulfonic acid group has proper hydrophilicity and can play a role of an auxiliary emulsifier, and the compound emulsifier formed based on compounds of the same structure and type can be fused more tightly; and a compact interface composite film is formed and has an excellent emulsification effect and good electrical stability and thermal stability.

Description

Emulsifier, preparation method thereof, and oil-based drilling fluid

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202310477151.5 filed on April 27, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of oil-based drilling fluid emulsifiers, in particular to an emulsifier, a preparation method thereof and oil-based drilling fluid. Background Art

[0004] Oil-based drilling fluids offer excellent properties such as strong inhibition, pollution resistance, lubrication, salt resistance, and minimal reservoir damage. They are increasingly used in water-sensitive formations, shale formations, deep wells, thick salt-gypsum layers, and salt rock formations. Emulsifiers are one of the most critical treatment agents for oil-based drilling fluids, primarily used to ensure the emulsion stability of water-in-oil drilling fluids and thereby improve their rheological properties. Currently, the emulsifier composition of oil-based drilling fluids mostly consists of a primary emulsifier and a secondary emulsifier, based on surfactants of varying structures and hydrophilicity. However, when surfactants of varying structures form an interfacial film, their dissimilarities lead to poor integration, hindering the emulsion's strength and stability. Furthermore, the presence of primary and secondary emulsifiers can increase the difficulty of field operations.

[0005] CN115785920A discloses an emulsifier for oil-in-water emulsified drilling fluid. The emulsifier is obtained by cyclizing fatty acids and organic amines as reactive monomers. The five-membered heterocyclic ring structure in the emulsifier's molecular structure ensures its stability in high-temperature environments. However, the emulsifier's demulsification voltage is below 400 V. CN105907382A discloses an emulsifier for oil-based drilling fluid. The emulsifier includes tall oil fatty acid, a polyamine, chloroacetamide, a surfactant, and an organic solvent. The emulsifier is compounded by adding a surfactant. However, only the temperature resistance of the emulsifier after aging at 150°C is disclosed.

[0006] Therefore, as bottomhole temperatures continue to hit new highs and the high-temperature resistance of oil-based / synthetic-based drilling fluid emulsifiers becomes increasingly prominent, how to further improve the electrical stability and temperature resistance of the oil-water emulsion system of oil-based drilling fluid and reduce the difficulty of operation is a technical problem that needs to be solved urgently.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of poor electrical stability and temperature resistance of the oil-water emulsion system in the prior art, and to provide an emulsifier and a preparation method thereof and an oil-based drilling fluid. The emulsifier has excellent emulsifying properties, good electrical stability and strong temperature resistance.

[0009] In order to achieve the above-mentioned object, the first aspect of the present invention provides an emulsifier, wherein the emulsifier comprises a compound having a polyene-polyamine skeleton and a hydrophobic group connected to the skeleton, and a portion of the polyene-polyamine skeleton is connected to a sulfonic acid group; wherein the molar ratio of sulfur element to nitrogen element in the emulsifier is 0.02-0.4:1.

[0010] A second aspect of the present invention provides a method for preparing an emulsifier, comprising: contacting a primary emulsifier with a sulfonating agent to carry out a sulfonation reaction to introduce sulfonic acid groups into a portion of the primary emulsifier; wherein the primary emulsifier has a polyene polyamine skeleton and a hydrophobic group connected to the skeleton; and the molar ratio of the sulfonating agent to the primary emulsifier calculated on the basis of the polyene polyamine skeleton is (0.1-0.5):1.

[0011] The third aspect of the present invention provides an emulsifier prepared by the above preparation method.

[0012] A fourth aspect of the present invention provides an oil-based drilling fluid, which comprises a base oil and a treatment agent, wherein the treatment agent comprises the emulsifier described in the first aspect or the third aspect.

[0013] The compound that the emulsifier provided by the present invention includes has polyene polyamine skeleton and the hydrophobic group being connected on the skeleton, and part of the polyene polyamine skeleton is connected with sulfonic acid group;The partial emulsifier not containing sulfonic acid group can play the role of primary emulsifier, makes primary emulsifier have stronger lipophilicity by the hydrophobic group being connected on the skeleton, forms adsorption film with certain intensity at oil-water interface, reduces oil-water interfacial tension;The partial emulsifier containing sulfonic acid group has suitable hydrophilicity, can play the role of auxiliary emulsifier, and the composite emulsifier composed of compound based on same structure and type can be more closely fused, forms dense interface composite film, strengthens emulsification effect. There is the mol ratio of suitable sulfur element and nitrogen element in the emulsifier, shows that there is suitable sulfonic acid group content in the emulsifier, controls the sulfur-nitrogen mol ratio to play the synergistic effect of primary emulsifier and auxiliary emulsifier within the above range, can effectively reduce oil-water interfacial tension, forms stable interfacial film, stops the coalescence of water droplets, makes oil-water emulsification system become stable. As an oil-based drilling fluid emulsifier, the emulsifier can make the demulsification voltage of the oil-water emulsion system reach 1089V. After aging at 180°C and 200°C, the demulsification voltage can reach a maximum of 974V and 648V, respectively. This shows that the emulsifier provided by the present invention has significantly superior emulsification stability compared to existing composite emulsifier systems.

[0014] The preparation method of the emulsifier provided by the present invention introduces sulfonic acid groups into a polyamine compound through a sulfonation reaction to obtain sulfonate substituents with partially corresponding structures. The main emulsifier and auxiliary emulsifier with the same structural type are synthesized through a "one-pot method", which can reduce production costs and steps and improve reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is an infrared absorption spectrum of the primary emulsifier prepared in Example 1 of the present invention;

[0016] FIG2 is a mass spectrum of the primary emulsifier prepared in Example 1 of the present invention;

[0017] FIG3 is an infrared absorption spectrum of emulsifier A1 prepared in Example 1 of the present invention;

[0018] FIG4 is a mass spectrum of emulsifier A1 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0020] A first aspect of the present invention provides an emulsifier, comprising a compound having a polyene-polyamine skeleton and a hydrophobic group connected to the skeleton, and a portion of the polyene-polyamine skeleton is connected to a sulfonic acid group; wherein the molar ratio of sulfur to nitrogen in the emulsifier is 0.02-0.4:1.

[0021] According to the present invention, part of the polyene polyamine skeleton contains a sulfonic acid group, that is, part of the polyene polyamine skeleton is connected to a sulfonic acid group, and the remaining part of the polyene polyamine skeleton is not connected to a sulfonic acid group. In this case, the compound without a sulfonic acid group in the skeleton can act as a primary emulsifier, and the compound containing a sulfonic acid group in the remaining skeleton can act as a secondary emulsifier. The primary emulsifier and the secondary emulsifier composed of compounds of the same structure and type can be more closely integrated. In the prior art, when surfactants based on different structures and hydrophilicity are used as emulsifiers, due to the different structures of different surfactants, integration is difficult and the stability is poor. Generally, they need to be assembled during on-site operation, which increases the difficulty of on-site operation.

[0022] In the present invention, the molar ratio of sulfur to nitrogen in the emulsifier is 0.02-0.4:1, for example, it can be 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, 0.2:1, 0.22:1, 0.24:1, 0.26:1, 0.28:1, 0.3:1, 0.35:1, 0.4:1 and other typical but non-limiting molar ratios or ranges therebetween. By controlling the appropriate molar ratio of sulfur to nitrogen in the emulsifier, indicating that the emulsifier has an appropriate relative content of polyene-polyamine backbone and sulfonic acid groups, the interaction between the two can effectively reduce the oil-water interfacial tension, form a stable interfacial film, prevent the coalescence of water droplets, and stabilize the oil-water emulsion system. Preferably, the molar ratio of sulfur to nitrogen in the emulsifier is 0.08-0.3:1, more preferably 0.1-0.2:1. In this preferred embodiment, the emulsifier's emulsification effect can be further enhanced, and its electrical and thermal stability can be improved.

[0023] In the present invention, an organic element analyzer is used to test the mass fractions of sulfur and nitrogen in the emulsifier, and then the molar ratio of sulfur to nitrogen is calculated.

[0024] According to the present invention, preferably, at a dosage of 5 wt%, the emulsifier has an emulsion breaking voltage of 50-400 V, preferably 80-280 V, and more preferably 200-280 V in a standard oil-based emulsion. The standard oil-based emulsion is composed of No. 5 white oil and a 25 wt% CaCl2 aqueous solution, with an oil-to-water volume ratio of 80:20. The dosage refers to the mass fraction of the emulsifier added based on the total mass of the oil and water. The inventors of the present invention have discovered that the emulsifier has a suitable emulsion breaking voltage in the standard oil-based emulsion. Within this preferred range, the emulsifier is advantageously used in actual oil-based drilling fluids and exhibits superior emulsification properties. The higher the demulsification voltage of the emulsifier in the standard oil-based emulsion, the better. Due to the complex composition of the actual drilling fluid, when the demulsification voltage of the emulsifier in the standard oil-based emulsion is too high, the emulsifier will show too high polarity in the actual oil-based drilling fluid, and the oil droplets formed will be too fine, which may lead to increased plastic viscosity and dynamic shear force, and poor electrical stability and thermal stability.

[0025] According to some preferred embodiments of the present invention, the emulsification rate of the emulsifier in the standard oil-based emulsion is ≥90%, preferably 95-100%.

[0026] According to the present invention, preferably, the molar ratio of the hydrophobic groups to the polyene polyamine backbone is (1-4):1, for example, a typical but non-limiting molar ratio of 1:1, 2:1, 3:1, 4:1, or a range therebetween. Preferably, the molar ratio of the hydrophobic groups to the polyene polyamine backbone is (2-3):1.

[0027] According to the present invention, preferably, based on the total amount of the emulsifier, the content of the polyene-polyamine skeleton is 5-20 wt%, preferably 10-15 wt%.

[0028] According to the present invention, preferably, the molar ratio of the sulfonic acid group to the polyene polyamine backbone is (0.1-1.2): 1, preferably (0.3-0.6): 1. In the above preferred case, the emulsification effect and stability of the emulsifier are further improved.

[0029] According to some preferred embodiments of the present invention, the emulsifier contains C, H, N, S and O elements.

[0030] Further preferably, based on the total amount of the emulsifier, the content of the C element is 50-75wt%, preferably 55-72wt%; the content of the H element is 5-15wt%, preferably 8-13wt%; the content of the N element is 2-8wt%, preferably 2.5-5.5wt%; the content of the S element is 0.5-2wt%, preferably 0.8-1.5wt%; and the content of the O element is 10-25wt%, preferably 11-20wt%. In the present invention, an organic element analyzer is used to test the elemental composition in the emulsifier. It is understandable that the emulsifier may also contain other elements, and the present invention is not particularly limited thereto.

[0031] In the present invention, the polyene polyamine backbone is selected from at least one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine backbones. It is understood that the H atom connected to at least one N atom in the polyene polyamine backbone is replaced by a hydrophobic group, thereby making the hydrophobic group connected to the polyene polyamine backbone. Preferably, the polyene polyamine backbone is selected from diethylenetriamine and / or triethylenetetramine.

[0032] In the present invention, the hydrophobic group is connected to the polyene polyamine skeleton via a covalent bond. Preferably, the hydrophobic group is connected to the N atom at the end of the polyene polyamine skeleton. In the above preferred case, the hydrophobic group is concentrated on the outside of the compound structure and synergistically acts with the internal hydrophilic polyene polyamine skeleton, which is beneficial to further improve the emulsification effect of the emulsifier and improve the electrical stability and thermal stability of the emulsified system.

[0033] In the present invention, hydrophobic group refers to that the structural unit is hydrophobic (lipophilic) on the whole, and the present invention has no particular limitation on the specific composition of the hydrophobic group. Preferably, the hydrophobic group contains at least one hydrophobic functional group. The present invention has a wider range of selection for the hydrophobic functional group. Preferably, the hydrophobic functional group is selected from at least one of an alkyl, an alkenyl, an alkynyl, an aryl and an ester group. For example, the hydrophobic group can be a straight or branched alkyl group of C3-C18, preferably any one of propyl, butyl, amyl, hexyl, heptyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and its isomers, and any one of the carbon atom or hydrogen atom in the above-mentioned alkyl group can also be replaced by a substituent, and the substituent can be any one of an ester group, a hydroxyl and a phenyl group. For example, the carbon atom at the end of the n-decyl group can be replaced by a methyl ester group. The hydrophobic group can also contain hydrophilic groups such as hydroxyl groups, which are not limited to meet the requirement that the structural unit is hydrophobic on the whole.

[0034] According to some preferred embodiments of the present invention, the hydrophobic group is Wherein, R4 is selected from H or a C5-C16 alkyl group; R5 is selected from a substituted or unsubstituted C5-C16 alkyl group, alkoxy group, aryl group, or phenoxy group. The C5-C16 alkyl group is preferably any one of propyl, butyl, pentyl, hexyl, heptyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, and isomers thereof. Any carbon atom or hydrogen atom in the above alkyl group may be substituted by a substituent, such as any one of an ester group, a hydroxyl group, and a phenyl group.

[0035] The present invention has no particular requirements for the specific structure of the sulfonic acid group-containing substituent. As long as part of the polyene polyamine skeleton contains a sulfonic acid group, it can play a synergistic emulsifying role with the compound without a sulfonic acid group. In order to further improve the emulsifying performance of the emulsifier, according to some preferred embodiments of the present invention, the structure of the sulfonic acid group is represented as follows: Wherein, R6 is selected from a substituted or unsubstituted C1-C8 alkylene group, y is 0 or 1, and M is selected from Na, K, or an ammonium group. For example, it can be any one of methylene, ethylene, propylene, butylene, and isomers thereof. The hydrogen atom on at least one carbon atom in the alkylene group may be replaced by a substituent, such as any one of a hydroxyl group, an ester group, and an ether group.

[0036] Preferably, M is selected from an alkali metal or an ammonium group, preferably Na, K or an ammonium group.

[0037] In the present invention, in formula (III), y is 0 or 1. It is understood that when y is 0, it means that the sulfonic acid group-containing substituent does not contain an alkylene group, and the sulfonic acid group is directly connected to the nitrogen atom.

[0038] According to some preferred embodiments of the present invention, the emulsifier includes a compound represented by formula (I);

[0039] wherein each R1 is independently selected from H or the sulfonic acid group, each R2 is independently selected from H or the hydrophobic group, and at least one R2 is not H, each R3 is independently selected from a substituted or unsubstituted C1-C3 alkylene group; and n is a positive integer between 1 and 3.

[0040] According to the present invention, in formula (I), R1 in the n repeating structural units may be the same or different and are independently selected from H or the sulfonic acid group, as long as a sulfonic acid group is connected to the polyene polyamine skeleton and the sulfur-nitrogen molar ratio meets the above requirements.

[0041] For example, when the polyene polyamine skeleton is triethylenetetramine, formula (I) can be expressed as Each R1 is independently selected from H or the sulfonic acid group; when the polyene polyamine skeleton is diethylenetriamine, formula (I) can be expressed as Each R1 is independently selected from H or the sulfonic acid group, and R1 has the same definition as above.

[0042] A second aspect of the present invention provides a method for preparing an emulsifier, comprising: contacting a primary emulsifier with a sulfonating agent to carry out a sulfonation reaction to introduce sulfonic acid groups into a portion of the primary emulsifier; wherein the primary emulsifier has a polyene polyamine skeleton and a hydrophobic group connected to the skeleton; and the molar ratio of the sulfonating agent to the primary emulsifier calculated on the basis of the polyene polyamine skeleton is (0.1-0.5):1.

[0043] The polyene polyamine skeleton and hydrophobic group have the same definitions as in the first aspect and will not be repeated here.

[0044] According to some preferred embodiments of the present invention, based on the total amount of the primary emulsifier, the content of the polyene-polyamine skeleton is 40-100 wt %, preferably 50-90 wt %.

[0045] According to some preferred embodiments of the present invention,

[0046] The primary emulsifier includes a compound having a structure shown in formula (i);

[0047] wherein each R2 is independently selected from H or the hydrophobic group, and at least one R2 is not H, and each R3 is independently selected from a substituted or unsubstituted C1-C3 alkylene group; and n is a positive integer between 1 and 3. wherein R2 and R3 have the same definitions as in the first aspect.

[0048] The present invention has no special requirements for the source of the primary emulsifier, and it can be prepared by any chemical reaction method known in the art.

[0049] According to some preferred embodiments of the present invention, the method for preparing the primary emulsifier comprises: subjecting a polyene polyamine to a ring-opening reaction with an epoxy compound;

[0050] Wherein, the epoxy compound has a structure shown in formula (a),

[0051] Wherein, R4 and R5 have the same definition as in the first aspect.

[0052] According to the present invention, in step (1), the hydrophobic group is introduced into the polyene polyamine by a ring-opening reaction with an epoxy compound.

[0053] According to the present invention, the structure of the polyene polyamine can be represented as wherein n and R3 have the same definitions as in the first aspect.

[0054] According to some preferred embodiments of the present invention, the polyene polyamine is selected from diethylenetriamine and / or triethylenetetramine.

[0055] According to some preferred embodiments of the present invention, the epoxy compound is preferably at least one of methyl 9,10-epoxyoctadecanoate (CAS: 6084-76-0), 1,2-epoxyoctadecane (CAS: 7390-81-0), and C10-16-alkyl glycidyl ether (CAS: 68081-84-5). The above-mentioned polyethylene polyamine and epoxy compound can be commercially available or prepared using known methods, and the present invention is not particularly limited thereto.

[0056] According to the present invention, preferably, the molar ratio of the polyene polyamine to the epoxy compound is 1:(1-5), for example, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, or other typical but non-limiting molar ratios or ranges therebetween. Preferably, the molar ratio of the polyene polyamine to the epoxy compound is 1:(1.5-3.5).

[0057] In the present invention, a polyene polyamine and an epoxy compound can be placed in a reactor to undergo a ring-opening reaction. The present invention has no particular requirements for the conditions of the ring-opening reaction, as long as they are conducive to the ring-opening reaction of the epoxy compound. Those skilled in the art can select the conditions according to actual needs. Preferably, the ring-opening reaction conditions include: a reaction temperature of 60-140° C., preferably 80-120° C., and a reaction time of 5-15 hours, preferably 6-12 hours.

[0058] Preferably, the ring-opening reaction is carried out under stirring conditions. The present invention has no particular limitation on the stirring conditions, as long as they are conducive to the reaction.

[0059] In the present invention, the ring-opening reaction can also be carried out in the presence of a catalyst. The present invention does not particularly limit the catalyst, and any catalyst known in the art that can promote the ring-opening reaction of epoxy compounds can be used in the present invention. For example, the catalyst can be an organic acid and / or an inorganic acid. Preferably, it is at least one of sulfuric acid, phosphoric acid, acetic acid, oxalic acid, trifluoroacetic acid, p-toluenesulfonic acid, and aminosulfonic acid, and more preferably at least one of sulfuric acid, phosphoric acid, acetic acid, and oxalic acid.

[0060] Preferably, the molar ratio of the catalyst to the epoxy compound is (0.001-0.02):1, preferably (0.003-0.015):1.

[0061] In the present invention, the product of the ring-opening reaction can be directly used as the primary emulsifier to continuously carry out the sulfonation reaction. Alternatively, the product mixture obtained from the ring-opening reaction can be purified first, and any unreacted raw materials can be removed by various means before the sulfonation reaction is carried out. The present invention has no particular requirements for this, as long as the product contains a compound of the target structure. Those skilled in the art can make the selection based on actual needs.

[0062] The present invention has no particular requirements for the specific type of the sulfonating agent, as long as it can introduce sulfonic acid groups into a portion of the primary emulsifier. Those skilled in the art can select the agent based on actual conditions. The present invention also has no particular restrictions on the source of the sulfonating agent, which can be purchased commercially or prepared by chemical reaction methods known in the art.

[0063] According to some preferred embodiments of the present invention, the sulfonating agent is a sulfonate and / or an alkyl sultone.

[0064] Preferably, the sulfonate has a structure shown in formula (ii),

[0065] Wherein, X is a halogen atom, preferably Cl or Br, R6 is selected from a substituted or unsubstituted C1-C8 alkylene group, preferably a C2-C4 alkylene group, for example, it can be any one of methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene or their isomers; y is 0 or 1; M is selected from Na, K or ammonium group.

[0066] According to some preferred embodiments of the present invention, the sulfonating agent is selected from at least one of sodium 3-chloro-2-hydroxypropane sulfonate (CAS: 126-83-0), 1,3-propane sultone (CAS: 1120-71-4) and / or 1,4-butane sultone (CAS: 1633-83-6), more preferably 1,3-propane sultone and / or 1,4-butane sultone.

[0067] According to the present invention, in order to promote the sulfonation reaction and prevent the formation of inorganic acid, preferably, the sulfonation reaction is carried out in the presence of an acid binding agent. The present invention is not particularly limited to the specific type of the acid binding agent, and conventional acid binding agents in the art can be used, for example, organic bases or inorganic bases, preferably inorganic bases, for example, at least one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

[0068] According to the present invention, preferably, the molar ratio of the acid binding agent to the sulfonating agent is (0.5-2.5):1, more preferably (0.5-2):1. In this preferred embodiment, the acid binding agent effectively binds the acidic byproducts produced during the reaction, promoting the forward reaction. At the same time, the acid binding agent is an alkaline salt, and adding an appropriate amount thereof can effectively reduce the formation of salt content without affecting the reaction, thereby preventing the reaction product from being too viscous and difficult to pour or use on site.

[0069] According to the present invention, preferably, the molar ratio of the sulfonating agent to the primary emulsifier, calculated as the polyene-polyamine backbone, is (0.1-0.5):1, preferably (0.2-0.4):1. By adopting the above preferred embodiment, the polyene-polyamine backbone in the prepared emulsifier can be controlled to have an appropriate degree of sulfonation, thereby further improving the emulsifying effect of the emulsifier and enhancing the electrical and thermal stability of the emulsified system.

[0070] The present invention does not particularly limit the specific conditions of the sulfonation reaction, as long as they are conducive to the sulfonation reaction, and those skilled in the art can select them according to actual needs. Preferably, the conditions of the sulfonation reaction include: a reaction temperature of 80-120° C. and a reaction time of 3-5 hours.

[0071] In the present invention, the sulfonation reaction can also be carried out in the presence of a solvent. The present invention has a wide range of choices for the solvent, and can select any organic solvent commonly used in the art, such as at least one of methanol, ethanol, n-octanol, isooctyl alcohol, dimethylformamide, dimethyl sulfoxide, and ethylene glycol. The present invention has no particular requirements for the amount of the solvent used, as long as it can fully disperse the reactants. Those skilled in the art can select the solvent based on actual needs.

[0072] According to some preferred embodiments of the present invention, the preparation method further comprises: removing the solvent from the mixture obtained by the sulfonation reaction. In the present invention, various methods can be used to remove the solvent from the product mixture, preferably using a reduced pressure distillation method. For example, the method for removing the solvent from the mixture obtained by the sulfonation reaction comprises: cooling the mixture obtained by the sulfonation reaction and then performing reduced pressure distillation. Preferably, the pressure of the reduced pressure distillation is 1-5kPa, preferably 1.2-2kPa, and the temperature is 40-80°C, preferably 45-60°C. In the present invention, unless otherwise specified, the pressure refers to absolute pressure.

[0073] According to a particularly preferred embodiment of the present invention, the preparation method of the emulsifier comprises:

[0074] (1) subjecting polyene polyamine to a ring-opening reaction with an epoxy compound;

[0075] Wherein, the epoxy compound has a structure shown in formula (a),

[0076] Wherein, R4 and R5 have the same definitions as in the first aspect;

[0077] (2) contacting the product of the ring-opening reaction with a sulfonating agent to perform a sulfonation reaction;

[0078] Wherein, the molar ratio of the polyene polyamine, the epoxy compound and the sulfonating agent is 1:(1-5):(0.2-0.5).

[0079] It should be noted that the product obtained by the above preparation method is usually present in the form of a mixture: step (1) is to obtain a primary emulsifier having a polyene polyamine skeleton and a hydrophobic group connected to the skeleton by a ring-opening reaction of a polyene polyamine and an epoxy compound, and then a sulfonic acid group is introduced into the polyene polyamine skeleton of part of the primary emulsifier by a sulfonation reaction to obtain a sulfonated product of the primary emulsifier. The primary emulsifier based on the same polyene polyamine skeleton structure and its sulfonated product can be more closely integrated as a composite emulsifier. The interaction between the two can effectively reduce the oil-water interfacial tension, form a stable interfacial film, prevent the coalescence of water droplets, and stabilize the oil-water emulsion system. The emulsifier has excellent emulsifying effect, good electrical stability and thermal stability as an oil-based drilling fluid emulsifier, can be effectively used in oil-based drilling fluids with different oil-water ratios and different types of base oils, and is suitable for the emulsification of oil-based drilling fluids such as gas oil, white oil, and diesel.

[0080] The third aspect of the present invention provides an emulsifier prepared by the above preparation method.

[0081] A fourth aspect of the present invention provides an oil-based drilling fluid, which comprises a base oil and a treatment agent, wherein the treatment agent comprises the above-mentioned emulsifier.

[0082] In the present invention, the base oil in the oil-based drilling fluid can be selected from a wide range of types and can be provided by any oil phase commonly used in the art. Those skilled in the art can select the base oil based on actual needs. Preferably, the base oil is selected from at least one of gas oil, white oil, and diesel, preferably white oil.

[0083] According to some preferred embodiments of the present invention, based on 100 parts by weight of the base oil, the content of the emulsifier is 2-10 parts by weight, preferably 3-5 parts by weight.

[0084] According to the present invention, the treatment agent may further include at least one of, for example, organic soil, a plugging agent, a weighting agent, a wetting agent, an alkaline regulator, and a fluid loss reducer. Those skilled in the art may select the agent based on actual needs, and the present invention is not particularly limited thereto.

[0085] According to some preferred embodiments of the present invention, the organic soil may be at least one of organically modified bentonite, organically modified sepiolite, and organically modified palygorskite. The present invention has no particular limitation on the source of the organic soil, which may be commercially available.

[0086] The present invention has no particular limitation on the source of the fluid loss agent, and commercially available products known to those skilled in the art can be used. Preferably, the fluid loss agent is selected from at least one of natural asphalt, oxidized asphalt, and styrene-butadiene rubber.

[0087] According to some preferred embodiments of the present invention, the weighting agent may be at least one of barite, micro-manganese ore powder, and iron ore powder.

[0088] According to some preferred embodiments of the present invention, the alkaline regulator may be calcium oxide and / or sodium carbonate, preferably calcium oxide.

[0089] In the present invention, the amounts of the fluid loss control agent, alkalinity control agent, and organic soil can be selected based on actual needs and are not particularly limited. According to some preferred embodiments of the present invention, based on 100 parts by weight of the base oil, the amount of the fluid loss control agent is 2-6 parts by weight, the amount of the alkalinity control agent is 0.5-2 parts by weight, and the amount of the organic soil is 0.5-3 parts by weight.

[0090] The present invention will be described in detail below through examples.

[0091] In the following examples and comparative examples, unless otherwise specified, all raw materials used were commercially available.

[0092] In the present invention, the method for testing the demulsification voltage and emulsification rate of an emulsifier in a standard oil-based emulsion comprises: stirring the emulsifier and No. 5 white oil at 10,000 rpm for 30 minutes to dissolve the emulsifier in the oil; then, adding a 25 wt% aqueous solution of CaCl2 at an oil-water ratio of 80:20 by volume; and stirring at 10,000 rpm for 2 hours to obtain the emulsion to be tested. The emulsifier is added at a dosage of 5 wt% based on the total weight of the oil and water.

[0093] Electrical stability test: Place the probe of the electrical stability tester in the emulsion to be tested, record and calculate the average value of the emulsion breaking voltage of the two measurement results, and the difference between the two readings shall not exceed 5%.

[0094] Emulsification rate test: After aging the emulsion to be tested at 150°C for 16 hours, cool it to room temperature, stir it at 10,000 rpm for 20 minutes, pour the emulsion into a 500 mL graduated cylinder, let it stand for 24 hours, and read the volume of the separated oil phase. The emulsification rate (W) is calculated as follows:

[0095] W = (V0 - V0) / V0 × 100%;

[0096] In the above formula, V0 is the volume of the emulsion, unit is mL; W is the emulsification rate, unit is %; V is the volume of the separated oil layer, unit is mL.

[0097] In the present invention, the content of C, H, O, N, and S in the product was measured using an organic element analyzer (Elementar Unicube). The molar ratio of sulfur and nitrogen in the emulsifier was further calculated.

[0098] In the present invention, the infrared absorption spectrum is tested using a Fourier transform infrared spectrometer, and the test mode is the ATR mode.

[0099] In the present invention, mass spectrometry is performed in a matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI-TOF / TOF), and the test conditions include: methanol dissolution, CHCA matrix.

[0100] Example 1

[0101] (1) In a double-necked round-bottom flask equipped with a reflux condenser, 20 mol of diethylenetriamine and 38 mol of 9,10-epoxyoctadecanoic acid methyl ester (CAS: 6084-76-0, commercially available, purity 75%) were added and stirred uniformly. 0.2 mol of p-toluenesulfonic acid was added, and the mixture was heated to 90°C and stirred for 7.5 h to obtain a primary emulsifier.

[0102] A portion of the main emulsifier was separated by silica gel column chromatography (petroleum ether: ethyl acetate 2:1-1:5), and the solvent was distilled out by rotary evaporator to obtain the purified product, which was then analyzed by infrared absorption spectrum. The results are shown in Figure 1. From the infrared absorption spectrum, it can be seen that the product has a strong affinity to the product at 1080-1160 cm -1 The absorption peak belonging to the epoxy bond disappears and is located at 3200-3500cm -1 The characteristic peaks belonging to the hydroxyl group are very obvious, indicating that a ring-opening reaction has occurred between diethylenetriamine and epoxy fatty acid methyl ester. The main emulsifier was subjected to mass spectrometry analysis, and the results are shown in Figure 2. It can be seen that the structures corresponding to the characteristic peaks with mass-to-charge ratios of 724.301, 726.307, and 728.298 are diethylenetriamine substituted with dihydroxy fatty acid methyl esters. The multi-peak signals are derived from the presence of linoleic acid methyl ester and oleic acid methyl ester in the 9,10-epoxyoctadecanoic acid methyl ester component, which will produce epoxy oleic acid methyl ester and epoxy linoleic acid methyl ester after epoxidation. The above results prove that the main emulsifier was successfully synthesized. Combining the results of mass spectrometry and infrared absorption spectroscopy, it is proved that the main emulsifier has the structure shown in formula (i), wherein the two R2 are R4 is an n-octyl methyl ester group, R5 is an n-octyl group, and the molar ratio of the hydrophobic group to the diethylenetriamine backbone is 2:1.

[0103] (2) The product obtained in step (1), 6 mol of sodium 3-chloro-2-hydroxypropane sulfonate and 150 mL of ethanol were mixed evenly, 6 mol of potassium carbonate was added, the mixture was heated to 80° C. and stirred for 3 h to obtain a second intermediate;

[0104] (3) After the second intermediate obtained in step (2) was cooled to room temperature, the solvent ethanol was distilled off under reduced pressure at 50° C. and 1.5 kPa to obtain emulsifier A1.

[0105] Emulsifier A1 was separated by silica gel column chromatography (dichloromethane: methanol 1:1-1:8), and the solvent was distilled out by rotary evaporator to obtain a purified product, which was then subjected to infrared absorption spectrum test. The infrared absorption spectrum is shown in FIG3 . It can be seen from the infrared absorption spectrum that the product has a peak at 3200-3500 cm -1 The characteristic absorption peak of hydroxyl group becomes larger, indicating that the content of hydroxyl group increases. -1 The presence of characteristic peaks attributable to sulfonate groups indicates the presence of sulfonate groups in the structure. The mass spectrometry analysis results are shown in Figure 4. The characteristic peak at a mass-to-charge ratio of 864.574 corresponds to a structure substituted with diethylenetriamine (DMSA) with sulfonic acid groups introduced. Combined with the results in Figures 3 and 4, this indicates that sulfonic acid groups have been introduced into the diethylenetriamine backbone of some primary emulsifiers. Analysis of the elemental composition using an organic element analyzer revealed 4.92 wt% N, 65.4 wt% C, 10 wt% H, 1.15 wt% S, and 16.95 wt% O. The molar ratio of sulfur to nitrogen in the emulsifier is 0.23:1. Based on the total amount of the emulsifier, the diethylenetriamine backbone content is 12 wt%. The molar ratio of sulfonic acid groups to the polyene polyamine backbone is 0.31:1.

[0106] The emulsification rate and demulsification voltage of emulsifier A1 in standard oil-based emulsion are shown in Table 1.

[0107] Example 2

[0108] (1) In a double-necked round-bottom flask equipped with a reflux condenser, 20 mol of diethylenetriamine and 38 mol of 9,10-epoxyoctadecanoic acid methyl ester (CAS: 6084-76-0) were added and mixed uniformly. 0.25 mol of sulfuric acid was added, and the mixture was heated to 100°C and stirred for 8 hours to obtain a primary emulsifier. The molar ratio of the hydrophobic group to the diethylenetriamine backbone was 2:1.

[0109] (2) The primary emulsifier, 6 mol of sodium 3-chloro-2-hydroxypropane sulfonate and 200 mL of isooctyl alcohol were mixed evenly, 6 mol of sodium hydroxide was added, the mixture was heated to 90° C. and stirred for 4 h;

[0110] (3) After cooling the product obtained in step (2) to room temperature, the solvent isooctyl alcohol is distilled off under reduced pressure at 50° C. and 1.2 kPa to obtain emulsifier A2.

[0111] Emulsifier A2 was separated by silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. The elemental composition was then analyzed using an organic element analyzer, revealing that the N content was 5.1wt%, the C content was 64.2wt%, the H content was 11.2wt%, the S content was 1.2wt%, and the O content was 16.7wt%. The molar ratio of sulfur to nitrogen in the emulsifier was 0.1:1. Based on the total amount of the emulsifier, the content of the diethylenetriamine skeleton was 12.5wt%. The molar ratio of the sulfonic acid group to the polyene polyamine skeleton was 0.31:1.

[0112] The emulsification rate and demulsification voltage of emulsifier A2 in standard oil-based emulsion are shown in Table 1.

[0113] Example 3

[0114] (1) In a double-necked round-bottom flask with a reflux condenser, 20 mol of triethylenetetramine and 45 mol of 9,10-epoxyoctadecanoic acid methyl ester (CAS: 6084-76-0) were added and stirred evenly. 0.3 mol of phosphoric acid was added and the mixture was heated to 80°C and stirred for 6 h to obtain a primary emulsifier. The molar ratio of the hydrophobic group to the triethylenetetramine skeleton was 2.25:1.

[0115] (2) The primary emulsifier, 8 mol of 3-chloro-2-hydroxypropanesulfonic acid sodium salt and 150 mL of isopropanol were mixed evenly, 4 mol of potassium carbonate was added, the mixture was heated to 80° C. and stirred for 3 h to obtain a second intermediate;

[0116] (3) After the second intermediate was cooled to room temperature, the solvent isopropyl alcohol was distilled off under reduced pressure at 50° C. and 1.2 kPa to obtain emulsifier A3.

[0117] Emulsifier A3 was separated using silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. The elemental composition was analyzed using an organic element analyzer, revealing that the N content was 4.3wt%, the C content was 64.4wt%, the H content was 10.7wt%, the S content was 1.1wt%, and the O content was 15.9wt%. The molar ratio of sulfur to nitrogen in the emulsifier was 0.14:1. Based on the total amount of the emulsifier, the content of the triethylenetetramine skeleton was 11.2wt%. The molar ratio of the sulfonic acid group to the polyene polyamine skeleton was 0.45:1.

[0118] The emulsification rate and demulsification voltage of emulsifier A3 in standard oil-based emulsion are shown in Table 1.

[0119] Example 4

[0120] (1) In a double-necked round-bottom flask equipped with a reflux condenser, 20 mol of triethylenetetramine and 52 mol of 9,10-epoxyoctadecanoic acid methyl ester (CAS: 6084-76-0) were added and stirred evenly. 0.2 mol of p-toluenesulfonic acid was added and the mixture was heated to 110°C and stirred for 12 h to obtain a first intermediate, wherein the molar ratio of the hydrophobic group to the triethylenetetramine skeleton was 2.6:1.

[0121] (2) The first intermediate, 8 mol of sodium 3-chloro-2-hydroxypropane sulfonate and 300 mL of n-octanol were mixed evenly, 8 mol of potassium carbonate was added, the mixture was heated to 120° C. and stirred for 5 h to obtain the second intermediate;

[0122] (3) After the second intermediate was cooled to room temperature, the solvent n-octanol was distilled off under reduced pressure at 50° C. and 1.2 kPa to obtain emulsifier A4.

[0123] Emulsifier A4 was separated using silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. The elemental composition was analyzed using an organic element analyzer, revealing that the N content was 4.0 wt%, the C content was 65.4 wt%, the H content was 11.4 wt%, the S content was 0.9 wt%, and the O content was 16.8 wt%. The molar ratio of sulfur to nitrogen in the emulsifier was 0.13:1. Based on the total amount of the emulsifier, the triethylenetetramine backbone content was 9.9 wt%. The molar ratio of the sulfonic acid group to the polyene polyamine backbone was 0.39:1.

[0124] The emulsification rate and demulsification voltage of emulsifier A4 in standard oil-based emulsion are shown in Table 1.

[0125] Example 5

[0126] The method of Example 1 was followed, except that 1,2-epoxydodecane was used in an equal molar amount to replace 9,10-epoxyoctadecanoic acid methyl ester (cas: 6084-76-0), to obtain emulsifier A5.

[0127] Emulsifier A5 was separated by silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. The elemental composition was analyzed using an organic element analyzer. The results showed that the N content was 5.9 wt%, the C content was 67.3 wt%, the H content was 11.9 wt%, the S content was 1.3 wt%, and the O content was 8.9 wt%. The molar ratio of sulfur to nitrogen in the emulsifier was 0.1:1. Based on the total amount of the emulsifier, the diethylenetriamine backbone content was 14.5 wt%. The molar ratio of the sulfonic acid group to the polyene polyamine backbone was 0.29:1.

[0128] The emulsification rate and demulsification voltage of emulsifier A5 in standard oil-based emulsion are shown in Table 1.

[0129] Example 6

[0130] The method of Example 1 was followed, except that an equal molar amount of 1,3-propane sultone was used to replace sodium 3-chloro-2-hydroxypropane sulfonate, to obtain emulsifier A6.

[0131] Emulsifier A6 was separated using silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. The elemental composition was analyzed using an organic element analyzer, revealing that the N content was 5.4wt%, the C content was 66.1wt%, the H content was 10.8wt%, the S content was 1.3wt%, and the O content was 15.1wt%. The molar ratio of sulfur to nitrogen in the emulsifier was 0.11:1. Based on the total amount of the emulsifier, the content of the diethylenetriamine skeleton was 13.2wt%. The molar ratio of the sulfonic acid group to the polyene polyamine skeleton was 0.32:1.

[0132] The emulsification rate and demulsification voltage of emulsifier A6 in standard oil-based emulsion are shown in Table 1.

[0133] Example 7

[0134] The method of Example 1 was followed, except that the amount of sodium 3-chloro-2-hydroxypropanesulfonate used was 14 mol, to obtain emulsifier A7.

[0135] Emulsifier A7 was separated using silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. Analysis of the elemental composition using an organic element analyzer revealed that the nitrogen content was 5.0 wt %, and the sulfur content was 2.73 wt %. The molar ratio of sulfur to nitrogen in the emulsifier was 0.24:1. Based on the total amount of the emulsifier, the diethylenetriamine backbone content was 11.9 wt %. The molar ratio of the sulfonic acid group to the polyene polyamine backbone was 0.71:1.

[0136] The emulsification rate and demulsification voltage of emulsifier A7 in standard oil-based emulsion are shown in Table 1.

[0137] Example 8

[0138] Emulsifier A8 was obtained by following the method of Example 1, except that the amount of sodium 3-chloro-2-hydroxypropane sulfonate used was 4.2 mol.

[0139] Emulsifier A8 was separated using silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. Analysis of the elemental composition using an organic element analyzer revealed that the nitrogen content was 5.6 wt %, and the sulfur content was 0.8 wt %. The molar ratio of sulfur to nitrogen in the emulsifier was 0.07:1. Based on the total amount of the emulsifier, the diethylenetriamine backbone content was 13.3 wt %. The molar ratio of the sulfonic acid group to the polyene polyamine backbone was 0.19:1.

[0140] The emulsification rate and demulsification voltage of emulsifier A8 in standard oil-based emulsion are shown in Table 1.

[0141] Comparative Example 1

[0142] The method of Example 1 was followed, except that steps (2) and (3) were not performed, and the primary emulsifier obtained in step (1) was used as emulsifier DA1.

[0143] The emulsification rate and demulsification voltage of emulsifier DA1 in standard oil-based emulsion are shown in Table 1.

[0144] Comparative Example 2

[0145] (1) In a double-necked round-bottom flask equipped with a reflux condenser, 20 mol of diethylenetriamine and 38 mol of methyl 9,10-epoxyoctadecanoate (CAS: 6084-76-0) were added and mixed evenly. 0.2 mol of p-toluenesulfonic acid was added, and the mixture was heated to 90°C and stirred for 7.5 hours to obtain the first intermediate.

[0146] (2) The first intermediate, 22 mol of 3-chloro-2-hydroxypropanesulfonic acid sodium salt and 1000 mL of n-octanol were mixed evenly, 22 mol of potassium carbonate was added, the mixture was heated to 100° C. and stirred for 4 h to obtain the second intermediate;

[0147] (3) After the second intermediate was cooled to room temperature, the solvent ethanol was distilled off under reduced pressure at 50°C and 1.2 kPa to obtain emulsifier DA2.

[0148] Emulsifier DA2 was separated using silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. Analysis of the elemental composition using an organic element analyzer revealed a nitrogen content of 4.1 wt% and a sulfur content of 3.4 wt%. The molar ratio of sulfur to nitrogen in the emulsifier was 0.36:1. Based on the total amount of the emulsifier, the diethylenetriamine backbone content was 10 wt%. The molar ratio of the sulfonic acid group to the polyene polyamine backbone was 1.09:1.

[0149] The emulsification rate and demulsification voltage of emulsifier DA2 in standard oil-based emulsion are shown in Table 1.

[0150] Comparative Example 3

[0151] (1) In a double-necked round-bottom flask equipped with a reflux condenser, 20 mol of triethylenetetramine and 40 mol of methyl 9,10-epoxyoctadecanoate (CAS: 6084-76-0) were added and mixed evenly, 0.2 mol of p-toluenesulfonic acid was added, and the mixture was heated to 80°C and stirred for 6 h to obtain the first intermediate;

[0152] (2) The first intermediate, 40 mol of 3-chloro-2-hydroxypropanesulfonic acid sodium salt and 2000 mL of n-octanol were mixed evenly, 40 mol of potassium carbonate was added, the mixture was heated to 120° C. and stirred for 8 h to obtain the second intermediate;

[0153] (3) After the second intermediate was cooled to room temperature, the solvent n-octanol was distilled off under reduced pressure at 50°C and 1.2 kPa to obtain emulsifier DA3.

[0154] Emulsifier DA3 was separated using silica gel column chromatography (dichloromethane:methanol 1:1-1:8), and the solvent was distilled off using a rotary evaporator to obtain a purified product. Analysis of the elemental composition using an organic element analyzer revealed that the nitrogen content was 5.1% by weight, and the sulfur content was 5.9% by weight. The molar ratio of sulfur to nitrogen in the emulsifier was 1.5:1. The triethylenetetramine backbone content, based on the total amount of the emulsifier, was 13.3% by weight. The molar ratio of the sulfonic acid group to the polyene polyamine backbone was 2.02:1.

[0155] The emulsification rate and demulsification voltage of emulsifier DA3 in standard oil-based emulsion are shown in Table 1.

[0156] Comparative Example 4

[0157] The main emulsifier Span 80 and the auxiliary emulsifier Tween 80 were mixed in a molar ratio of 3:1 to serve as emulsifier DA4.

[0158] The emulsification rate and demulsification voltage of emulsifier DA4 in standard oil-based emulsion are shown in Table 1.

[0159] Table 1

[0160] Test Case

[0161] Drilling fluid configuration:

[0162] To 100 parts by weight of 5# white oil, 4 parts by weight of the emulsifiers in the above examples and comparative examples were added, and the mixture was stirred at 10,000 rpm for 30 minutes. Then, a 25 wt% calcium chloride solution was added at a volume ratio of 80:20. Then, to 100 parts by weight of 5# white oil, 4 parts by weight of natural asphalt, 2 parts by weight of calcium oxide, and 2 parts by weight of organic bentonite were added. Then, barite was added to increase the density to 1.8-2.2 g / cm 3 Continuing high stirring for 2 hours, the density was 2g / cm 3 Oil-based drilling fluid.

[0163] (1) Electrical stability test: Place the probe of the electrical stability tester in the oil-based drilling fluid obtained by the above configuration, record and calculate the average demulsification voltage value of the two measurement results, and the difference between the two readings shall not exceed 5%.

[0164] The drilling fluid's plastic viscosity (PV), dynamic shear stress (YP), and fluid loss at high temperature and high pressure (FLHTHP) were tested in accordance with the national standard GB / T16783.2-2012, "Field Testing of Drilling Fluids in the Petroleum and Natural Gas Industry—Part 2: Oil-Based Drilling Fluids." The results are shown in Table 2.

[0165] Table 2

[0166] (2) Thermal stability test

[0167] The drilling fluids obtained by the above configurations were aged at 180°C for 24 h, and then the drilling fluid performance tests were performed using the same method. The results are shown in Table 3.

[0168] The drilling fluids obtained by the above configurations were aged at 200°C for 96 h, and then the drilling fluid performance tests were performed using the same method. The results are shown in Table 4.

[0169] Table 3

[0170] Table 4

[0171] From the results in Tables 2-4, it can be seen that compared with the comparative example, the emulsifier product prepared in the embodiment of the present invention has obvious advantages in emulsification rate and electrical stability.

[0172] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. An emulsifier, characterized in that The emulsifier has a polyene polyamine skeleton and a hydrophobic group connected to the skeleton, and a part of the polyene polyamine skeleton is connected to a sulfonic acid group; wherein the molar ratio of sulfur element to nitrogen element in the emulsifier is 0.02-0.4:

1.

2. The emulsifier according to claim 1, wherein The molar ratio of sulfur to nitrogen in the emulsifier is 0.08-0.3:1, preferably 0.1-0.2:1; Preferably, the molar ratio of the hydrophobic group to the polyene polyamine backbone is (1-4):1, preferably (2-3):

1.

3. The emulsifier according to claim 1 or 2, wherein Based on the total amount of the emulsifier, the content of the polyene polyamine skeleton is 5-20wt%, preferably 10-15wt%; Preferably, the molar ratio of the sulfonic acid group to the polyene polyamine backbone is (0.1-1.2):1, preferably (0.3-0.6):

1.

4. The emulsifier according to any one of claims 1 to 3, wherein The emulsifier contains C, H, N, S and O elements; Preferably, based on the total amount of the emulsifier, the content of the C element is 50-75wt%, the content of the H element is 5-15wt%, the content of the N element is 2-8wt%, the content of the S element is 0.5-2wt%, and the content of the O element is 10-25wt%.

5. The emulsifier according to any one of claims 1 to 4, wherein The polyene polyamine skeleton is selected from at least one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine skeletons; Preferably, the hydrophobic group contains at least one hydrophobic functional group, preferably at least one of a C5-C16 alkyl group, an alkenyl group, an alkynyl group, an aryl group and an ester group; Preferably, the hydrophobic group is Among them, R4 is selected from H or C5-C16 alkyl, preferably any one of n-hexyl, n-octyl, n-decyl, and n-dodecyl; R5 is selected from substituted or unsubstituted C5-C16 alkyl, alkoxy, aryl or phenoxy.

6. The emulsifier according to any one of claims 1 to 5, wherein The structure of the sulfonic acid group is represented by Wherein, R6 is selected from substituted or unsubstituted C1-C8 alkylene, y is 0 or 1; and M is selected from Na, K or ammonium.

7. The emulsifier according to any one of claims 1 to 6, wherein The emulsifier includes a compound represented by formula (I); Wherein, each R1 is independently selected from H or the sulfonic acid group, each R2 is independently selected from H or the hydrophobic group, and at least one R2 is not H, each R3 is independently selected from substituted or unsubstituted C1-C3 alkylene; n is a positive integer between 1-3.

8. The emulsifier according to any one of claims 1 to 7, wherein Under the condition of 5wt% addition, the emulsion breaking voltage of the emulsifier in the standard oil-based emulsion is 50-400V, preferably 200-280V, wherein the standard oil-based emulsion is composed of No. 5 white oil and 25wt% CaCl2 aqueous solution, and the oil-water volume ratio is 80:20; Preferably, the emulsification rate of the emulsifier in the standard oil-based emulsion is ≥ 90%, preferably 95-100%.

9. A method for preparing an emulsifier, comprising: The primary emulsifier is contacted with a sulfonating agent to carry out a sulfonation reaction, so as to introduce sulfonic acid groups into part of the primary emulsifier; wherein the primary emulsifier has a polyene polyamine skeleton and a hydrophobic group connected to the skeleton; The molar ratio of the sulfonating agent to the primary emulsifier calculated on the basis of the polyene polyamine skeleton is (0.1-0.5):

1.

10. The preparation method according to claim 9, wherein: The molar ratio of the sulfonating agent to the primary emulsifier calculated on the basis of the polyene polyamine skeleton is (0.2-0.4):1; And / or, the conditions of the sulfonation reaction include: reaction temperature of 80-120° C., time of 3-5 h; Preferably, the sulfonation reaction is carried out in the presence of an acid binding agent, and the molar ratio of the acid binding agent to the sulfonating agent is (0.5-2.5):

1.

11. The preparation method according to claim 9 or 10, wherein: The molar ratio of the hydrophobic group to the polyene polyamine backbone is (1-4):1, preferably (2-3):

1.

12. The preparation method according to any one of claims 9 to 11, wherein: The polyene polyamine skeleton is selected from at least one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine skeletons; and / or, The hydrophobic group contains at least one hydrophobic group, preferably at least one of a C5-C16 alkyl, alkenyl, alkynyl, aryl and ester group; Preferably, the hydrophobic group is Among them, R4 is selected from H or C5-C16 alkyl, preferably any one of n-hexyl, n-octyl, n-decyl, and n-dodecyl; R5 is selected from substituted or unsubstituted C5-C16 alkyl, alkoxy, aryl or phenoxy.

13. The preparation method according to any one of claims 9 to 12, wherein: The primary emulsifier includes a compound having a structure shown in formula (i); Wherein, each R2 is independently selected from H or the hydrophobic group, and at least one R2 is not H, each R3 is independently selected from substituted or unsubstituted C1-C3 alkylene; n is a positive integer between 1-3.

14. The preparation method according to any one of claims 9 to 13, wherein: The sulfonating agent is selected from sulfonates and / or alkyl sultones; Preferably, the sulfonate has a structure shown in formula (ii), Wherein, X is a halogen atom, preferably Cl or Br; R7 is selected from substituted or unsubstituted C1-C8 alkylene, y is 0 or 1; M is selected from Na, K or ammonium; Preferably, the alkyl sultone is selected from C3-C5 alkyl sultones, preferably 1,3-propane sultone and / or 1,4-butane sultone.

15. An emulsifier obtained by the preparation method according to any one of claims 9 to 14.

16. An oil-based drilling fluid, characterized in that: The oil-based drilling fluid comprises a base oil and a treating agent, wherein the treating agent comprises the emulsifier according to any one of claims 1 to 8 and 15; Preferably, based on 100 parts by weight of the base oil, the content of the emulsifier is 2-10 parts by weight.

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