Water-based functional gemini surfactant and preparation method thereof

Abstract

The invention belongs to the technical field of surfactants for foam drilling fluids in petroleum and natural gas development, and relates to a water-based functional gemini surfactant and a preparation method thereof. The preparation method comprises the following steps: S1, mixing a bio-based hydrophilic matrix with a first alcohol solvent, adding a silane pre-activator, and carrying out a nucleophilic transesterification reaction; s2, mixing the pre-activated bio-based hydrophilic matrix, bio-based polyoxyethylene ether glycidyl ether and a second alcohol solvent, adding a supported composite catalyst, and carrying out a nucleophilic ring-opening reaction; and S3, dissolving the bio-based gemini surfactant skeleton in a polar solvent, firstly adding a first sulfonating agent to carry out substitution sulfonation reaction at low temperature, then heating to a certain temperature, and adding a second sulfonating agent to carry out nucleophilic addition sulfonation reaction. The prepared surfactant can remarkably improve the high characteristic value stability of the foam drilling fluid, and is especially suitable for extreme industrial application scenes such as high-temperature deep wells and high-salt oil reservoirs.

Description

Technical Field

[0001] This invention belongs to the technical field of surfactants for foam drilling fluids in oil and gas development, specifically relating to a water-based functional gemini surfactant and its preparation method. Background Technology

[0002] In oil drilling operations, foam drilling fluid, as a key technical means, plays a crucial role in carrying drill cuttings, stabilizing the wellbore, and cooling the drill bit. Surfactants are the key components that determine the foaming and foam-stabilizing properties of foam drilling fluid. As drilling depth extends to deep and ultra-deep wells, the bottom-hole ambient temperature often reaches 200-260℃, and the formation water salinity generally exceeds 15%. Traditional surfactants face severe challenges: on the one hand, molecular chains are prone to breakage at high temperatures, leading to a sharp decline in foam stability, with the foam half-life dropping to less than 30% of its initial value within 12 hours; on the other hand, salt precipitation easily occurs in high-salt environments, resulting in a decrease in hydrophilicity and failing to meet the requirements of drilling operations.

[0003] Gemini surfactants, containing two hydrophilic and two hydrophobic groups, possess advantages such as low critical micelle concentration and high surface activity, making them a research hotspot. However, existing gemini surfactants still have drawbacks: First, their upper temperature resistance is generally below 180℃, and their structure is easily damaged at temperatures above 200℃; second, the preparation process often uses chemically synthesized crosslinking agents and single strong base catalysts, which not only result in poor biocompatibility and environmental pollution, but also make catalyst recovery difficult, increasing production costs; third, their salt resistance is insufficient, and they are prone to failure in high-salt solutions above 15%, limiting their application in extreme drilling scenarios.

[0004] Therefore, developing a twin-type surfactant with high temperature resistance and high salt resistance in a water-based system, and with a green and environmentally friendly preparation process, is of great significance for improving the adaptability of foam drilling fluid to extreme environments and ensuring drilling operation efficiency.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] To address the problems of poor temperature resistance, insufficient salt resistance, and environmentally unfriendly preparation methods of existing gemini surfactants, this invention provides a water-based functional gemini surfactant and its preparation method. Through molecular structure design and green process optimization, the surfactant achieves stable performance under high temperature and high salt environments, while reducing environmental pollution and costs in the preparation process.

[0007] To overcome the shortcomings of the prior art, the present invention provides the following technical solution:

[0008] A method for preparing a water-based functional gemini surfactant includes the following steps:

[0009] S1. Mix the bio-based hydrophilic matrix with a first alcohol solvent, add a silane pre-activator, and carry out a nucleophilic transesterification reaction; after the reaction is completed, remove the solvent and byproducts by vacuum distillation to obtain the pre-activated bio-based hydrophilic matrix;

[0010] S2. The pre-activated bio-based hydrophilic matrix, bio-based polyoxyethylene ether glycidyl ether, and a second alcohol solvent are mixed, ultrasonically dispersed, and then a supported composite catalyst is added to carry out a nucleophilic ring-opening reaction. After the reaction is completed, the catalyst is recovered by vacuum filtration, and the solvent is removed by vacuum distillation to obtain a bio-based gemini surfactant skeleton.

[0011] S3. Dissolve the bio-based gemini surfactant skeleton in a polar solvent, add a first sulfonating agent to carry out a substitution sulfonation reaction, then heat to a certain temperature and add a second sulfonating agent to carry out a nucleophilic addition sulfonation reaction; after the reaction is completed, adjust the pH of the system to neutral, remove the solvent by vacuum distillation, and obtain a water-based functional gemini surfactant.

[0012] Further, in step S1, the bio-based hydrophilic matrix is ​​a natural glycoside compound, and the purity of the natural glycoside compound is ≥95%; the natural glycoside compound is selected from one or more of camellia saponins, sophora japonica saponins, and glycyrrhizin.

[0013] And / or, the silane preactivator is an aminosilane coupling agent selected from one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane; the first alcohol solvent is a low-carbon chain alcohol selected from one or more of anhydrous ethanol, isopropanol, and n-butanol.

[0014] Further, in step S1, the conditions for the nucleophilic transesterification reaction are: reaction temperature 25~60℃, stirring speed 100~400rpm, reaction time 1-3h; the mass ratio of the bio-based hydrophilic matrix to the first alcohol solvent is 1:(2~8); the mass ratio of the silane pre-activator to the bio-based hydrophilic matrix is ​​1:(5~15); the vacuum degree of vacuum distillation is 0.09~0.095MPa, and the temperature is 60-80℃.

[0015] Further, in step S2, the bio-based polyoxyethylene ether glycidyl ether is selected from one or more of cashew phenol polyoxyethylene ether glycidyl ether, tea saponin derivative glycidyl ether, and castor oil-based glycidyl ether; the second alcohol solvent is a low-carbon chain alcohol, selected from one or more of anhydrous ethanol, isopropanol, and n-butanol.

[0016] And / or, the supported composite catalyst is a composite catalyst in which a supported alkali metal hydroxide is supported as an active component on the surface and pores of a metal oxide, and is selected from one or more mixtures of NaOH supported on Al2O3 and KOH supported on Al2O3.

[0017] Further, in step S2, the ultrasonic dispersion time is 5-10 min; the conditions for the nucleophilic ring-opening reaction are: reaction temperature 60-110℃, stirring speed 100-500 rpm, and reaction time 2-6 h.

[0018] And / or, the mass ratio of the pre-activated bio-based hydrophilic matrix to the bio-based polyoxyethylene ether glycidyl ether is 2:(1~3), and the mass ratio of the pre-activated bio-based hydrophilic matrix to the second alcohol solvent is 1:(4~10); the mass of the supported composite catalyst is 1%~5% of the total mass of the pre-activated bio-based hydrophilic matrix, the bio-based polyoxyethylene ether glycidyl ether, and the second alcohol solvent; the vacuum degree of the vacuum distillation is 0.09~0.095MPa, and the temperature is 100~120℃.

[0019] Further, in step S3, the first sulfonating agent is a sulfonyl chloride compound selected from one or more of chlorosulfonic acid, methanesulfonyl chloride, and benzenesulfonyl chloride; the second sulfonating agent is a sulfite compound selected from one or more of sodium sulfite, potassium sulfite, and ammonium sulfite; and the polar solvent is selected from one or more of deionized water, dichloromethane, and chloroform.

[0020] Further, in step S3, the conditions for the substitution sulfonation reaction are: reaction temperature 0~20℃, stirring speed 100~300rpm, and reaction time 1~3h; the conditions for the nucleophilic addition sulfonation reaction are: temperature 50~90℃, stirring speed 200~250rpm, and reaction time 1~4h.

[0021] And / or, the mass ratio of the bio-based gemini surfactant skeleton to the polar solvent is 1:(5~12), the mass ratio of the first sulfonating agent to the bio-based gemini surfactant skeleton is 1:(5-20), and the mass ratio of the second sulfonating agent to the bio-based gemini surfactant skeleton is 1:(4~15).

[0022] And / or, the alkaline solution used to adjust the pH of the system is a 5-15% NaOH or KOH solution; the vacuum degree of the vacuum distillation is 0.09-0.095 MPa, and the temperature is 120-130℃.

[0023] In addition, the present invention provides a water-based functional Gemini surfactant, which is prepared by the above-described preparation method; the surfactant has a surface tension ≤27mN / m at 25°C, a surface tension ≤32mN / m after aging at 220°C for 24h, and a solubility ≥35g / L in a 20% NaCl solution without salting out.

[0024] In addition, the present invention also provides an application of the water-based functional gemini surfactant as described above, wherein the water-based functional gemini surfactant is added to the foam drilling fluid for drilling operations in high-temperature deep wells above 200°C or high-salt oil reservoirs with 20% NaCl.

[0025] Furthermore, the amount of the water-based functional Gemini surfactant added to the foam drilling fluid is 0.1% to 1.0% of the total mass of the foam drilling fluid.

[0026] Compared with the prior art, the technical solution of the present invention has at least the following technical effects:

[0027] (1) By introducing a rigid aromatic ring structure through a bio-based crosslinking agent, the thermal stability of the surfactant is improved at the molecular level. The π-π conjugated system of the benzene ring forms a rigid skeleton with the molecular backbone, which inhibits the thermal degradation and rearrangement of the molecular chain at high temperature. After accelerated testing at 220℃ for 24h, the surface tension of the product remained at 30-32mN / m, and the foaming height maintained more than 90% of the initial value. In contrast, the surface tension of traditional Gemini surfactants rose to more than 36mN / m after aging at 180℃ for 24h. At 220℃, the molecular chain broke, and the surface tension suddenly rose to more than 45mN / m (complete failure), which can meet the requirements of high-temperature deep well operations.

[0028] (2) A stepwise sulfonation process is used to introduce hydrophilic units of disulfonic acid groups, forming a "synergistic effect of bipolar groups," which significantly improves salt resistance. In a 20% NaCl high-salt solution, the dense negative charge layer formed after the dissociation of disulfonic acid groups hinders the encapsulation of hydrophilic groups by salt ions through charge repulsion, and the product solubility still reaches more than 35 g / L, while traditional monosulfonic acid surfactants will salt out in 15% NaCl solution (solubility ≤ 5 g / L). Foam performance tests show that the foam half-life of this product in 20% NaCl solution reaches 180-200 min, which is more than twice that of traditional products (80-90 min); in a simulated high-salt reservoir environment (20% NaCl, 180℃), the foam stability retention rate reaches 85%, solving the industry pain point that traditional products are prone to failure in high-salt formations.

[0029] (3) Bio-based crosslinking agents are used, with raw materials derived from natural plant oils or plant extracts. The biodegradability rate is over 90% (compliant with GB / T 27857-2011 standard), which is more environmentally friendly than traditional chemically synthesized crosslinking agents (such as ethylene glycol diglycidyl ether, with a biodegradability rate ≤30%). The supported composite catalyst can be recovered by filtration, with a recovery rate of over 85%. After being reused 5 times, the catalytic activity still maintains 90% of the initial value, achieving green production.

[0030] (4) The foam drilling fluid with the surfactant of this invention, under extreme conditions of 220℃ and 20% NaCl, still maintains a foam characteristic value (the ratio of gas volume to total foam volume) of over 85%, far exceeding the industry standard (≥60%). In the cuttings carrying simulation experiment, the cuttings (particle size 0.5-2mm) carrying efficiency reached 92%, which is 40% higher than that of drilling fluid with traditional surfactants (66%). The wellbore stability experiment showed that the wellbore stability time in shale formations was extended to 120h, while that of traditional products was only 50h, effectively reducing the incidence of wellbore collapse, stuck pipe and other accidents. Field test data showed that the drilling operation efficiency using this product was increased by 35%, and the drilling cost per well was reduced by more than 200,000 yuan, demonstrating significant industrial application value.

[0031] (5) In addition to the field of foam drilling fluids, the product of this invention exhibits excellent performance in high-temperature and high-salt reservoir oil displacement and industrial high-temperature cleaning due to its ultra-high temperature resistance and high salt resistance. In oil displacement applications, under 15% salt concentration and 200℃ conditions, the oil displacement efficiency reaches 65-70%, which is 15-20% higher than that of traditional surfactants (50-55%), and the crude oil production increase rate of a single well reaches more than 12%. In the field of industrial high-temperature cleaning, when used for cleaning oil stains on equipment at 200℃, the oil stain removal rate reaches 98%, and the equipment is free from corrosion after cleaning (corrosion rate ≤0.02mm / a, in line with GB / T 25146-2010 standard), which is superior to traditional high-temperature cleaning agents (removal rate 85%, corrosion rate 0.08mm / a). In addition, the product can also be applied to high-temperature emulsification demulsification, tertiary oil recovery additives, and other scenarios, realizing a broad-spectrum application of "one product for multiple scenarios". Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0033] Figure 1 A photograph of the amino-activated camellia saponin prepared in Example 1;

[0034] Figure 2 A photograph of the cashew phenol gemini surfactant skeleton prepared in Example 1;

[0035] Figure 3 A photograph of the water-based functional gemini surfactant prepared in Example 1;

[0036] Figure 4 The image shows the results of the foam characteristic value test.

[0037] Figure 5 The image shows the FT-IR spectrum of the amino-activated camellia saponin prepared in Example 1.

[0038] Figure 6 FT-IR image of the water-based functional gemini surfactant prepared in Example 1. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0040] The endpoints and any values ​​of the ranges disclosed in this invention 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0041] Terminology definition:

[0042] Bio-based hydrophilic matrices refer to compounds derived from natural plants that have multiple hydroxyl or glycoside structures and can provide hydrophilic sites; Gemini surfactant skeletons refer to bihydrophobic-bihydrophilic structural units formed by cross-linking two hydrophilic matrix units through bio-based polyoxyethylene ether segments.

[0043] This invention breaks through the traditional preparation approach, adopting an unconventional scheme of "bio-based crosslinking agent + composite supported catalysis + stepwise grafting modification". Through precise molecular structure design, rigid aromatic rings and disulfonic acid groups are introduced into the bio-based hydrophilic matrix framework, aiming to prepare a high-temperature and salt-resistant gemini surfactant. This solves the defect of performance degradation in extreme environments of existing technologies, ensuring that the foam drilling fluid can maintain high characteristic values ​​in high-temperature environments above 200°C and high-salt environments of 20%, providing reliable protection for drilling operations under extreme conditions.

[0044] The ultra-high temperature resistant and salt-resistant gemini surfactant prepared by this invention has a core molecular structure characterized by "rigid aromatic ring connecting bridge + disulfonic acid group hydrophilic unit". The core preparation idea is as follows: First, an aminosilane pre-activator is used to pre-activate the bio-based hydrophilic matrix, introducing active amino groups into its molecular chain to enhance the subsequent reaction activity; then, bio-based polyoxyethylene ether glycidyl ether is selected as a crosslinking agent, and under the action of a supported composite catalyst, it undergoes a crosslinking reaction with the activated bio-based hydrophilic matrix to form a gemini framework containing a rigid aromatic ring. The rigid structure can improve the molecular thermal stability; finally, sulfonation is performed stepwise with sulfonyl chloride and sulfite reagents to introduce disulfonic acid groups into the molecular chain, and the salt resistance is enhanced through the "synergistic effect of bipolar groups", thus obtaining an ultra-high temperature resistant and salt-resistant functional surfactant.

[0045] The specific reaction mechanism is as follows:

[0046] 1. Pre-activation reaction: The bio-based hydrophilic matrix contains a primary hydroxyl group (-CH2OH) in its molecular structure. The oxygen atom of this hydroxyl group has a lone pair of electrons, which can undergo a nucleophilic transesterification reaction with the alkoxy group in the aminosilane coupling agent molecule—the hydrogen atom of the primary hydroxyl group transfers to the oxygen atom of the alkoxy group, forming an easily leaving ethanol molecule. Simultaneously, the oxygen atom of the camellia saponin forms a stable Si-OC covalent bond with the silicon atom of the silane molecule, grafting the amino (-NH2)-containing silane segment onto the bio-based hydrophilic matrix molecular backbone. The amino (-NH2) group is a strong electron-donating group, activating the oxygen atom of the adjacent hydroxyl group through conjugation and inductive effects, increasing its electron cloud density, enhancing nucleophilic reactivity, and effectively reducing the formation of byproducts.

[0047] 2. Cross-linking reaction: The supported composite catalyst carrier immobilizes the active components through physical adsorption, preventing the aggregation and deactivation of active sites during the reaction. The amino group (-NH2) in the activated bio-based hydrophilic matrix molecule acts as a nucleophilic center, attacking the epoxy group (three-membered ring structure) in the bio-based polyoxyethylene ether glycidyl ether molecule. This causes the highly ring-strained epoxy group to undergo a nucleophilic ring-opening reaction, forming a secondary amine structure containing a hydroxyl group (-OH). Ultimately, the two activated bio-based hydrophilic matrix molecules are linked through bio-based polyoxyethylene ether segments to form a twin structure. The key lies in the fact that after the benzene ring (rigid aromatic ring) in the bio-based molecule is embedded in the molecular backbone, the rotational freedom of the molecular chain can be restricted through π-π conjugation. When in a high-temperature environment (220℃), the steric hindrance effect of the benzene ring suppresses the thermal vibration amplitude of the molecular chain, ultimately increasing the thermal decomposition temperature of the product from 185℃ of the traditional product to 240℃, and breaking through the upper limit of temperature resistance to 220℃.

[0048] 3. Stepwise sulfonation reaction: The first step is substitution sulfonation—the sulfonyl chloride group (-SO3Cl) in sulfonyl chloride compounds has strong electron-withdrawing properties, attacking the oxygen atom of the secondary hydroxyl group (-CHOH-) on the twin backbone molecular chain, undergoing a nucleophilic substitution reaction. The hydroxyl group is replaced by the sulfonyl group (-SO3H), generating a monosulfonic acid intermediate, and releasing HCl gas (collected through a tail gas absorption device). The second step is addition sulfonation—the small amount of epoxy group remaining from the cross-linking reaction undergoes a nucleophilic addition reaction under the action of sulfite compounds. The sulfite ion attacks the carbon atom of the epoxy group, opening the ring and introducing a second sulfonic acid group (-SO3Na). The disulfonic acid groups are symmetrically distributed on the molecular chain, forming a dense negatively charged region after dissociation. When in a high-salt solution (20% NaCl), sodium ions are adsorbed by the negatively charged region to form an electric double layer. Through the charge repulsion effect, the direct binding of salt ions and hydrophilic groups is hindered, avoiding the hydrophilicity degradation caused by salt ion encapsulation in traditional monosulfonic acid products, and significantly improving salt resistance.

[0049] The specific technical solution is as follows:

[0050] The surfactant is made from the following raw materials: a bio-based hydrophilic matrix; an aminosilane pre-activator; a bio-based polyoxyethylene ether glycidyl ether; a supported composite catalyst; sulfonyl chloride compounds; and sulfite compounds.

[0051] The production method is as follows:

[0052] Step 1: Preparation of pre-activated bio-based hydrophilic matrix

[0053] The bio-based hydrophilic matrix and a first alcohol solvent were added to a three-necked glass flask and stirred until uniformly dispersed. Then, a silane pre-activator was added dropwise, controlling the emulsification temperature at 25-60℃ and the stirring speed at 100-400 rpm, maintaining the reaction temperature for 1-3 hours. After the reaction was complete, excess solvent and byproducts were removed by vacuum distillation to obtain the pre-activated bio-based hydrophilic matrix. The mass ratio of the bio-based hydrophilic matrix to the alcohol solvent was 1:(2-8); the mass ratio of the silane pre-activator to the bio-based hydrophilic matrix was 1:(5-15).

[0054] Step 2: Preparation of bio-based twin surfactant framework

[0055] The pre-activated bio-based hydrophilic matrix, bio-based polyoxyethylene ether glycidyl ether crosslinking agent, and second alcohol solvent obtained in step 1 were added to a three-necked glass flask. After ultrasonic dispersion for 5-10 min, the supported composite catalyst was added, stirring was started, and the reaction temperature was controlled at 60-110℃, the stirring speed at 100-500 rpm, and the reaction was maintained at this temperature for 2-6 h. Subsequently, after cooling to room temperature, the catalyst was recovered by vacuum filtration, and the solvent was removed from the filtrate by vacuum distillation to obtain the bio-based gemini surfactant skeleton. The mass ratio of the pre-activated bio-based hydrophilic matrix to the bio-based crosslinking agent was 2:(1-3); the mass of the supported composite catalyst was 1%-5% of the total mass of the system; and the mass ratio of the pre-activated bio-based hydrophilic matrix to the alcohol solvent was 1:(4-10).

[0056] Step 3, Preparation of high-temperature resistant and salt-resistant functional surfactants:

[0057] The bio-based gemini surfactant skeleton obtained in step 2 was dissolved in a polar solvent, and a first sulfonating agent was added. The reaction temperature was controlled at 0-20℃, the stirring speed at 100-300 rpm, and the reaction was carried out for 1-3 hours. Subsequently, the temperature was raised to 50-90℃, a second sulfonating agent was added, and the reaction was continued for 1-4 hours. After the reaction was completed, the pH was adjusted to 6.5-7.5 with a 5%-15% alkaline solution, and the solvent was removed by vacuum distillation in a rotary evaporator to obtain the target product—a high-characteristic-value, temperature- and salt-resistant functional surfactant for foam drilling fluids. The mass ratio of the first sulfonating agent to the bio-based gemini skeleton was 1:(5-20); the mass ratio of the second sulfonating agent to the bio-based gemini skeleton was 1:(4-15); and the mass ratio of the bio-based gemini skeleton to the polar solvent was 1:(5-12).

[0058] In the above preparation method, as a preferred embodiment, the bio-based hydrophilic matrix in step 1 is a natural glycoside compound, more preferably one or a mixture of two or more of camellia saponin (purity ≥95%), sophora japonica saponin, and glycyrrhizin, with camellia saponin being the most preferred; the alcohol solvent is a low-carbon chain alcohol, more preferably one or a mixture of two or more of anhydrous ethanol, isopropanol, and n-butanol; the silane preactivator is an aminosilane coupling agent, more preferably γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, or N-(β-aminoethyl)- One or more of γ-aminopropyltriethoxysilanes; preferred reaction conditions: emulsification temperature 50-60℃, stirring speed 200-300rpm, reaction time 1.5-2h; preferred raw material ratio: bio-based hydrophilic matrix to alcohol solvent mass ratio 1:(3-5), silane pre-activator to bio-based hydrophilic matrix mass ratio 1:(8-10).

[0059] In the above preparation method, as a preferred embodiment, the bio-based polyoxyethylene ether glycidyl ether crosslinking agent in step 2 is further preferably one or a mixture of two or more of cashew phenol polyoxyethylene ether glycidyl ether, tea saponin derivative glycidyl ether, and castor oil-based glycidyl ether; the supported composite catalyst is an alkali metal / metal oxide supported catalyst, further preferably one or a mixture of two or more of supported NaOH / Al2O3 (NaOH loading of 10-20 wt%) and KOH / Al2O3 (KOH loading of 10-20 wt%); the alcohol solvent is preferably the same as in step 1; preferred reaction conditions: reaction Temperature 90-100℃, stirring speed 200-300rpm, reaction time 3-4h, ultrasonic dispersion time 8-10min; after cooling to 25℃, filter by suction, vacuum distillation 0.09-0.095MPa, temperature 110℃; preferred raw material ratio: mass ratio of pre-activated bio-based hydrophilic matrix to bio-based crosslinking agent 2:(1-1.2), catalyst mass is 2%-3% of the mass of pre-activated bio-based hydrophilic matrix, bio-based polyoxyethylene ether glycidyl ether and second alcohol solvent, mass ratio of pre-activated bio-based hydrophilic matrix to alcohol solvent 1:(5-7).

[0060] In the above preparation method, as a preferred embodiment, in step 3, the first sulfonating agent is a sulfonyl chloride compound, more preferably one or a mixture of two or more of chlorosulfonic acid, methanesulfonyl chloride, and benzenesulfonyl chloride; the second sulfonating agent is a sulfite compound, more preferably one or a mixture of two or more of sodium sulfite, potassium sulfite, and ammonium sulfite; the polar solvent is water or a halogenated hydrocarbon, more preferably one or a mixture of two or more of deionized water, dichloromethane, and trichloromethane; the alkaline solution is a strong alkaline solution, more preferably NaOH solution or KOH solution. One or more mixtures in solution; preferred reaction conditions: temperature of 5-10℃ for the first sulfonation stage, stirring speed of 150-200 rpm, reaction time of 1-1.5 h; temperature of 70-80℃ for the second sulfonation stage, stirring speed of 200-250 rpm, reaction time of 2-3 h; rotary evaporation vacuum of 0.09-0.095 MPa, temperature of 120-130℃; preferred raw material ratio: mass ratio of first sulfonating agent to bio-based twin framework of 1:(10-12), mass ratio of second sulfonating agent to bio-based twin framework of 1:(8-10), mass ratio of bio-based twin framework to polar solvent of 1:(6-8).

[0061] The present invention will now be described in detail with reference to embodiments thereof. These examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present invention encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0062] In the embodiments of the present invention, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0063] Example 1

[0064] (1) Pre-activation of bio-based hydrophilic matrix:

[0065] 50g of camellia saponin solution, which had been vacuum dried for 4 hours and dehydrated, was slowly added to a three-necked flask along with 200mL of anhydrous ethanol. A magnetic stirrer was turned on at 300 rpm, and the oil bath was heated to 60°C. The mixture was stirred until the raw materials were completely dissolved, forming a transparent solution. Then, 6.0g of γ-aminopropyltriethoxysilane was slowly added dropwise through a constant-pressure dropping funnel. The reaction was maintained at this temperature for 2 hours, after which the oil bath was turned off. The reaction solution was transferred to a rotary evaporator, and the ethanol was removed by vacuum distillation at 0.09MPa and 70°C, yielding a pale yellow, viscous amino-activated camellia saponin (e.g., ...). Figure 1 (As shown).

[0066] Fourier transform infrared spectroscopy was performed on camellia saponins and amino-activated camellia saponins, and the results are as follows: Figure 5 As shown. 2840cm -1 -2940cm -1 The absorption peaks are due to the stretching vibrations of the CH bonds in the alkyl chains of both molecules, at 2500 cm⁻¹. -1 Up to 1900cm -1 No characteristic absorption is observed within the range, indicating the absence of triple or double bonds; 1640 cm⁻¹ -1 The peak for the C=O stretching vibration of camellia saponins and amino-activated camellia saponins is 1057 cm⁻¹. -1 The peak represents the COC stretching vibration of camellia saponins and amino-activated camellia saponins. In the infrared spectrum of amino-activated camellia saponins, the peak is at 1507 cm⁻¹. -1 The characteristic peak of NH appeared at 940 cm⁻¹. -1 The presence of the CN characteristic peak indicates that the amino coupling agent has reacted with camellia saponins; and the absorption peak of camellia saponins -OH after amino activation shifts to the right, indicating that the intermolecular hydrogen bonding is strengthened, further verifying the success of amino activation.

[0067] (2) Preparation of bio-based twin surfactant backbones:

[0068] Weigh 40.0 g of the activated camellia saponins and 32.6 g of cashew phenol polyoxyethylene ether glycidyl ether into a three-necked flask, and add 260 mL of anhydrous ethanol as a solvent. Disperse the mixture ultrasonically for 10 min to ensure homogeneity. Then add 3.63 g of supported NaOH / Al2O3 catalyst, turn on magnetic stirring at 300 r / min, heat the oil bath to 100 °C, and reflux for 4 h. Turn off the oil bath and allow the system to cool to 25 °C. Filter the catalyst using a Buchner funnel to recover the catalyst, and seal and store the recovered catalyst for future reuse. Transfer the filtrate to a rotary evaporator and distill under reduced pressure at 0.09 MPa and 110 °C. Collect the fraction at 120-130 °C to obtain a white solid cashew phenol gemini surfactant skeleton (e.g., ...). Figure 2 (As shown).

[0069] (3) Stepwise sulfonation preparation of high-temperature resistant and salt-resistant surfactants:

[0070] Weigh 50.0 g of the above-mentioned Gemini framework and dissolve it in 300 mL of deionized water. Add the solution to a flask, cool it to 5 °C in an ice bath, and start magnetic stirring at 200 r / min. Slowly add 5.0 g of chlorosulfonic acid dropwise through a constant pressure dropping funnel, maintaining the system temperature ≤10 °C. After the addition is complete, remove the ice bath, heat the solution to 20 °C in an oil bath, and continue the reaction for 2 h. Then, directly add 5.0 g of sodium sulfite, heat to 75 °C, and maintain the reaction for 2 h. After the reaction is complete, adjust the pH of the system to neutral with 10% NaOH solution. Then, transfer the reaction solution to a rotary evaporator for distillation, removing water under a vacuum of 0.09 MPa and 130 °C to obtain a pale yellow viscous target product (e.g., ...). Figure 3 (As shown).

[0071] Fourier transform infrared spectroscopy (FTIR) was performed on the cashew phenol gemini surfactant backbone and the target product (functional gemini surfactant), and the results are shown in Figure 6. The cashew phenol gemini surfactant backbone showed no characteristic epoxy group peaks in its FTIR spectrum, but a peak was observed at 1502 cm⁻¹. -1 The presence of an NH characteristic peak at 1583 cm⁻¹ indicates that the epoxy groups in cashew phenol polyoxyethylene ether glycidyl ether have fully reacted with the amino-activated camellia saponins; simultaneously, the cashew phenol gemini surfactant skeleton exhibits a peak at 1583 cm⁻¹. -1 The presence of a characteristic peak for the C=C bond of the aromatic ring at 1600 cm⁻¹ indicates that the benzene ring did not participate in the reaction and still provides high rigidity to the molecule. The characteristic peaks of the functional gemini surfactant formed after sulfonation are basically consistent with the skeleton of the cashew phenol gemini surfactant, indicating that the molecular structure has not undergone significant changes. Furthermore, the characteristic peaks at 1600 cm⁻¹ are also consistent with the characteristic peaks of the cashew phenol gemini surfactant. -1The presence of the S=O characteristic peak indicates that the cashew phenol gemini surfactant skeleton has been successfully sulfonated.

[0072] Example 2

[0073] (1) Pre-activation of bio-based hydrophilic matrix:

[0074] 50g of a sophora japonica saponin solution, which had been vacuum dried for 4 hours and dehydrated, was slowly added to a three-necked flask along with 200mL of anhydrous ethanol. A magnetic stirrer was turned on at 300 rpm, and the oil bath was heated to 60°C. The mixture was stirred until the raw materials were completely dissolved, forming a transparent solution. Then, 6.0g of γ-aminopropyltrimethoxysilane was slowly added dropwise through a constant-pressure dropping funnel. The reaction mixture was kept at this temperature for 2 hours, after which the oil bath was turned off. The reaction solution was transferred to a rotary evaporator, and the ethanol was removed by vacuum distillation at 0.09MPa and 70°C, yielding a pale yellow, viscous, amino-activated sophora japonica saponin.

[0075] (2) Preparation of bio-based twin surfactant backbones:

[0076] 40.0 g of the activated sophora japonica saponins and 32.6 g of tea saponin derivative polyoxyethylene ether glycidyl ether were weighed and added to a three-necked flask. 260 mL of anhydrous ethanol was added as a solvent, and the mixture was ultrasonically dispersed for 10 min to ensure homogeneity. Then, 3.63 g of supported NaOH / Al₂O₃ catalyst was added, and the mixture was magnetically stirred at 300 r / min. The oil bath temperature was raised to 100 °C, and the mixture was refluxed and maintained at this temperature for 4 h. The oil bath was then closed, and the system was allowed to cool to 25 °C. The catalyst was recovered by vacuum filtration using a Buchner funnel and sealed for future reuse. The filtrate was transferred to a rotary evaporator and distilled under reduced pressure at 0.09 MPa and 110 °C. The fraction collected at 120–130 °C yielded a white solid cashew phenol gemini surfactant skeleton.

[0077] (3) Stepwise sulfonation preparation of high-temperature resistant and salt-resistant surfactants:

[0078] Weigh 50.0 g of the above-mentioned Gemini framework and dissolve it in 300 mL of deionized water. Add the solution to a flask, cool it to 5 °C in an ice bath, and start magnetic stirring at 200 r / min. Slowly add 5.0 g of methanesulfonyl chloride through a constant pressure dropping funnel, maintaining the system temperature ≤10 °C. After the addition is complete, remove the ice bath, heat the solution to 20 °C in an oil bath, and continue the reaction for 2 h. Then, directly add 5.0 g of potassium sulfite, heat to 75 °C, and maintain the reaction temperature for 2 h. After the reaction is complete, adjust the pH of the system to neutral with 10% KOH solution. Then, transfer the reaction solution to a rotary evaporator for distillation, removing water under a vacuum of 0.09 MPa and 130 °C to obtain a pale yellow viscous target product.

[0079] Example 3

[0080] (1) Pre-activation of bio-based hydrophilic matrix:

[0081] 50g of glycyrrhizin solution, which had been vacuum dried for 4 hours and dehydrated, was slowly added to a three-necked flask along with 200mL of anhydrous ethanol. A magnetic stirrer was turned on at 300 rpm, and the oil bath was heated to 60°C. The mixture was stirred until the raw materials were completely dissolved, forming a transparent solution. Then, 6.0g of N-(β-aminoethyl)-γ-aminopropyltriethoxysilane was slowly added dropwise through a constant-pressure dropping funnel. The reaction mixture was kept at this temperature for 2 hours, after which the oil bath was turned off. The reaction solution was transferred to a rotary evaporator, and the ethanol was removed by vacuum distillation at 0.09MPa and 70°C, yielding a pale yellow, viscous amino-activated glycyrrhizin.

[0082] (2) Preparation of bio-based twin surfactant backbones:

[0083] Weigh 40.0 g of the activated glycyrrhizin and 32.6 g of castor oil-based polyoxyethylene ether glycidyl ether into a three-necked flask, and add 260 mL of anhydrous ethanol as a solvent. Sonicate the mixture for 10 min to ensure homogeneity. Then add 3.63 g of supported KOH / Al₂O₃ catalyst, turn on magnetic stirring at 300 r / min, heat the oil bath to 100 °C, and reflux for 4 h. Turn off the oil bath and allow the system to cool to 25 °C. Filter the catalyst using a Buchner funnel to recover the catalyst, and seal and store the recovered catalyst for future reuse. Transfer the filtrate to a rotary evaporator and distill under reduced pressure at 0.09 MPa and 110 °C. Collect the fraction at 120-130 °C to obtain a white solid cashew phenol gemini surfactant skeleton.

[0084] (3) Stepwise sulfonation preparation of high-temperature resistant and salt-resistant surfactants:

[0085] Weigh 50.0 g of the above-mentioned Gemini framework and dissolve it in 300 mL of deionized water. Add the solution to a flask, cool it to 5 °C in an ice bath, and start magnetic stirring at 200 r / min. Slowly add 5.0 g of benzenesulfonyl chloride dropwise through a constant pressure dropping funnel, maintaining the system temperature ≤10 °C. After the addition is complete, remove the ice bath, heat the solution to 20 °C in an oil bath, and continue the reaction for 2 h. Then, directly add 5.0 g of ammonium sulfite, heat to 75 °C, and maintain the reaction temperature for 2 h. After the reaction is complete, adjust the pH of the system to neutral with 10% NaOH solution. Then, transfer the reaction solution to a rotary evaporator for distillation, removing water under a vacuum of 0.09 MPa and 130 °C to obtain a pale yellow viscous target product.

[0086] Comparative Example 1

[0087] (1) Pre-activation of bio-based hydrophilic matrix:

[0088] 50g of camellia saponin solution, which had been vacuum dried for 4 hours and dehydrated, was slowly added to a three-necked flask along with 200mL of anhydrous ethanol. A magnetic stirrer was turned on at 300 rpm, and the oil bath was heated to 60°C. The mixture was stirred until the raw materials were completely dissolved, forming a transparent solution. Then, 15.0g of γ-aminopropyltriethoxysilane was slowly added dropwise through a constant-pressure dropping funnel. The reaction mixture was kept at this temperature for 2 hours, after which the oil bath was turned off. The reaction solution was transferred to a rotary evaporator, and the ethanol was removed by vacuum distillation at 0.09MPa and 70°C, yielding a pale yellow, viscous amino-activated camellia saponin.

[0089] (2) Preparation of bio-based twin surfactant backbones:

[0090] Weigh 40.0 g of the activated camellia saponins and 28.0 g of cashew phenol polyoxyethylene ether glycidyl ether into a three-necked flask, and add 260 mL of anhydrous ethanol as a solvent. Sonicate the mixture for 10 min to ensure homogeneity. Then add 3.63 g of NaOH catalyst, turn on the magnetic stirrer at 300 r / min, heat the oil bath to 100 °C, and reflux for 4 h. Turn off the oil bath and allow the system to cool to 25 °C. Transfer the filtrate to a rotary evaporator and distill under reduced pressure at 0.09 MPa and 110 °C. Collect the fraction at 120-130 °C to obtain a white solid cashew phenol gemini surfactant skeleton.

[0091] (3) Stepwise sulfonation preparation of high-temperature resistant and salt-resistant surfactants:

[0092] Weigh 50.0 g of the above-mentioned Gemini framework and dissolve it in 300 mL of deionized water. Add the solution to a flask, cool it to 5 °C in an ice bath, and start magnetic stirring at 200 r / min. Slowly add 10.0 g of chlorosulfonic acid dropwise through a constant pressure dropping funnel, maintaining the system temperature ≤10 °C. After the addition is complete, remove the ice bath, heat the solution to 20 °C in an oil bath, and continue the reaction for 2 h. Then, directly add 15.0 g of sodium sulfite, heat to 75 °C, and maintain the reaction for 2 h. After the reaction is complete, adjust the pH of the system to neutral with 10% NaOH solution. Then, transfer the reaction solution to a rotary evaporator for distillation, removing water under a vacuum of 0.09 MPa and 130 °C to obtain a pale yellow viscous target product.

[0093] Comparative Example 2

[0094] (1) Pre-activation of bio-based hydrophilic matrix:

[0095] 50g of camellia saponin solution, which had been vacuum dried for 4 hours and dehydrated, was slowly added to a three-necked flask along with 200mL of anhydrous ethanol. A magnetic stirrer was turned on at 300 rpm, and the oil bath was heated to 60°C. The mixture was stirred until the raw materials were completely dissolved, forming a transparent solution. Then, 2.0g of γ-aminopropyltriethoxysilane was slowly added dropwise through a constant-pressure dropping funnel. The reaction was maintained at this temperature for 2 hours, after which the oil bath was turned off. The reaction solution was transferred to a rotary evaporator, and the ethanol was removed by vacuum distillation at 0.09MPa and 70°C, yielding a pale yellow, viscous amino-activated camellia saponin.

[0096] (2) Preparation of bio-based twin surfactant backbones:

[0097] Weigh 40.0 g of the activated camellia saponins and 32.6 g of cashew phenol polyoxyethylene ether glycidyl ether into a three-necked flask, and add 260 mL of anhydrous ethanol as a solvent. Sonicate the mixture for 10 min to ensure homogeneity. Then add 3.63 g of supported NaOH / Al2O3 catalyst, turn on magnetic stirring at 300 r / min, heat the oil bath to 100 °C, and reflux for 1 h. Turn off the oil bath and allow the system to cool to 25 °C. Filter the catalyst using a Buchner funnel to recover the catalyst, and seal and store the recovered catalyst for future reuse. Transfer the filtrate to a rotary evaporator and distill under reduced pressure at 0.09 MPa and 110 °C. Collect the fraction at 120-130 °C to obtain a white solid cashew phenol gemini surfactant skeleton.

[0098] (3) Stepwise sulfonation preparation of high-temperature resistant and salt-resistant surfactants:

[0099] Weigh 50.0 g of the above-mentioned Gemini framework and dissolve it in 300 mL of deionized water. Add the solution to a flask, cool it to 5 °C in an ice bath, and start magnetic stirring at 200 r / min. Slowly add 2.0 g of chlorosulfonic acid dropwise through a constant pressure dropping funnel, maintaining the system temperature ≤10 °C. After the addition is complete, remove the ice bath, heat the solution to 20 °C in an oil bath, and continue the reaction for 2 h. Then, directly add 4.0 g of sodium sulfite, heat to 75 °C, and maintain the temperature for 2 h. After the reaction is complete, adjust the pH of the system to neutral with 10% NaOH solution. Then, transfer the reaction solution to a rotary evaporator for distillation, removing water under a vacuum of 0.09 MPa and 130 °C to obtain a pale yellow viscous target product.

[0100] The surface tension, foaming height, and half-life of the products from the above examples and comparative examples were tested after aging at room temperature (25°C) and 220°C for 24 hours. The test results are shown in Table 1 below. Figure 4 As shown (foaming height was measured using a Roche foam meter, in mm; half-life was measured using gravity displacement method, in min).

[0101] Table 1

[0102] Combined with Table 1, Figure 4 The data shows that, regarding the half-life of foam at room temperature, the example foam exhibits a 52.5%-60% improvement compared to Comparative Example 1 and a 103.3%-113.3% improvement compared to Comparative Example 2. At 220℃, the half-life of the example foam is 3.0-3.3 times that of Comparative Example 1 and 5.2-5.6 times that of Comparative Example 2. Regarding the foaming height of 20% NaCl solution, the example foam exhibits 1.5-1.6 times that of Comparative Example 1 and 2.2-2.4 times that of Comparative Example 2, with no salting out. These differences stem from defects in the comparative examples' processes: Comparative Example 1 suffers from a lack of rigid aromatic rings in the chemical crosslinking agent and excessive pre-activator leading to disordered structural branching, resulting in a sharp drop in high-temperature stability and salt resistance; Comparative Example 2 suffers from insufficient pre-activation and incomplete reaction, resulting in insufficient introduction of disulfonic acid groups, severely diminishing its hydrophilicity and foam stability. The comparison shows that the experimentally prepared ultra-high temperature and high salt-resistant functional surfactant can still maintain the stability of its molecular structure under high temperature and high salt conditions, and continue to play a role in stabilizing foam. This ensures that the foam drilling fluid can maintain high characteristic values ​​in complex environments such as high temperature deep wells, providing reliable protection for drilling operations.

[0103] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any technical solutions obtained by means of equivalent substitution or equivalent transformation should be covered within the protection scope of the present invention.

Claims

1. A process for the preparation of water-based functional gemini surfactants, characterized by, The method comprises the following steps: S1, mixing a bio-based hydrophilic matrix with a first alcohol solvent, adding a silane pre-activating agent, and performing a nucleophilic ester exchange reaction; after the reaction is completed, the solvent and by-products are removed by vacuum distillation to obtain a pre-activated bio-based hydrophilic matrix; S2, mixing the pre-activated bio-based hydrophilic matrix, a bio-based polyoxyethylene glycidyl ether with a second alcohol solvent, performing ultrasonic dispersion, adding a supported composite catalyst, and performing a nucleophilic ring-opening reaction; after the reaction is completed, the catalyst is recovered by suction filtration, and the solvent is removed by vacuum distillation to obtain a bio-based gemini surfactant skeleton; S3, dissolving the bio-based gemini surfactant skeleton in a polar solvent, first adding a first sulfonating agent to perform a substitution sulfonation reaction, then heating to a certain temperature, and adding a second sulfonating agent to perform a nucleophilic addition sulfonation reaction; after the reaction is completed, the pH of the system is adjusted to neutral, and the solvent is removed by vacuum distillation to obtain a water-based functional gemini surfactant.

2. The production method according to claim 1, characterized by, In step S1, the bio-based hydrophilic matrix is a natural glycoside compound, and the purity of the natural glycoside compound is ≥95%; the natural glycoside compound is selected from one or more than two mixtures of sasanqua saponin, sophora saponin, and glycyrrhiza saponin; And / or, the silane pre-activating agent is an amino silane coupling agent selected from one or more than two mixtures of γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyl triethoxysilane; the first alcohol solvent is a low-carbon chain alcohol selected from one or more than two mixtures of anhydrous ethanol, isopropyl alcohol, and n-butanol.

3. The preparation method according to claim 1, characterized in that, In step S1, the nucleophilic ester exchange reaction is performed under the following conditions: a reaction temperature of 25-60℃, a stirring speed of 100-400 rpm, and a reaction time of 1-3h; the mass ratio of the bio-based hydrophilic matrix to the first alcohol solvent is 1:(2-8); the mass ratio of the silane pre-activating agent to the bio-based hydrophilic matrix is 1:(5-15); the vacuum degree of the vacuum distillation is 0.09-0.095 MPa, and the temperature is 60-80℃.

4. The method of claim 1, wherein, In step S2, the bio-based polyoxyethylene glycidyl ether is selected from one or more than two mixtures of cardanol polyoxyethylene glycidyl ether, tea saponin derivative glycidyl ether, and castor oil glycidyl ether; the second alcohol solvent is a low-carbon chain alcohol selected from one or more than two mixtures of anhydrous ethanol, isopropyl alcohol, and n-butanol; And / or, the supported composite catalyst is a composite catalyst in which a supported alkali metal hydroxide is loaded on the surface and pores of a metal oxide as an active component, and is selected from one or more than two mixtures of NaOH loaded on Al2O3 and KOH loaded on Al2O3.

5. The preparation method according to claim 1, characterized in that, In step S2, the ultrasonic dispersion time is 5-10 min; the nucleophilic ring-opening reaction is performed under the following conditions: a reaction temperature of 60-110℃, a stirring speed of 100-500 rpm, and a reaction time of 2-6h; And / or, the mass ratio of the pre-activated bio-based hydrophilic matrix to the bio-based polyoxyethylene glycidyl ether is 2: (1-3), the mass ratio of the pre-activated bio-based hydrophilic matrix to the second alcohol solvent is 1: (4-10); the mass of the supported composite catalyst is 1%-5% of the total mass of the pre-activated bio-based hydrophilic matrix, the bio-based polyoxyethylene glycidyl ether and the second alcohol solvent; the vacuum degree of the reduced pressure distillation is 0.09-0.095 MPa, and the temperature is 100-120℃.

6. The method of claim 1, wherein, In step S3, the first sulfonating agent is a sulfuryl chloride compound selected from one or more than two mixtures of chlorosulfonic acid, methylsulfonyl chloride and benzenesulfonyl chloride; the second sulfonating agent is a sulfite compound selected from one or more than two mixtures of sodium sulfite, potassium sulfite and ammonium sulfite; and the polar solvent is selected from one or more than two mixtures of deionized water, dichloromethane and trichloromethane.

7. The preparation method according to claim 1, characterized in that, In step S3, the conditions of the substitution sulfonation reaction are as follows: reaction temperature 0-20℃, stirring speed 100-300 rpm, and reaction time 1-3h; and the conditions of the nucleophilic addition sulfonation reaction are as follows: temperature 50-90℃, stirring speed 200-250 rpm, and reaction time 1-4h. And / or, the mass ratio of the bio-based gemini surfactant skeleton to the polar solvent is 1: (5-12), the mass ratio of the first sulfonating agent to the bio-based gemini surfactant skeleton is 1: (5-20), and the mass ratio of the second sulfonating agent to the bio-based gemini surfactant skeleton is 1: (4-15). And / or, the alkaline solution used for adjusting the pH of the system is a NaOH solution or a KOH solution with a mass fraction of 5%-15%; and the vacuum degree of the reduced pressure distillation is 0.09-0.095 MPa, and the temperature is 120-130℃.

8. A water-based functional gemini surfactant, characterized by, Prepared by the preparation method of any one of claims 1-7; the surface tension of the surfactant is ≤27 mN / m at 25℃, the surface tension is ≤32 mN / m after aging at 220℃ for 24h, the solubility in a 20% NaCl solution is ≥35 g / L without salting-out phenomenon.

9. Use of a water-based functional gemini surfactant as claimed in claim 8, wherein, The water-based functional gemini surfactant is added to a foam drilling fluid for drilling operations in high-temperature deep wells above 200℃ or high-salt oil reservoirs with 20% NaCl.

10. Use according to claim 9, characterized in that, The addition amount of the water-based functional gemini surfactant in the foam drilling fluid is 0.1%-1.0% of the total mass of the foam drilling fluid. The addition amount of the water-based functional gemini surfactant in the foam drilling fluid is 0.1%-1.0% of the total mass of the foam drilling fluid.

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