CN115286526B - Surfactant and preparation method and application thereof - Google Patents

Abstract

The invention discloses a surfactant and its preparation method and application. The structural formula of the surfactant is: . The reaction between hydroxybenzyl alcohol and tetradecane bromide gives p-tetradecyloxybenzyl alcohol; add phosphorus tribromide to the methylene chloride solution of p-tetradecyloxybenzyl alcohol, and extract after the reaction is completed. The solvent in the organic layer is evaporated to dryness to obtain p-tetradecyloxybenzyl bromide; it is mixed with dimethylamine in the solvent, reacted, then washed and separated, and the solvent in the organic layer is evaporated to dryness to obtain p-tetradecyloxybenzyl bromide. dimethylamine; then mix it with chloroacetate in a solvent, react, and then evaporate the solvent to dryness and wash to obtain the surfactant. By directly adding water to the surfactant, a clean fracturing fluid can be obtained, making the clean fracturing fluid system single-component and simple to prepare; by changing the surfactant concentration, the viscosity of the clean fracturing fluid can be continuously maintained within 4-87 mPa∙s Adjustable; and the clean fracturing fluid has good salt resistance.

Description

A surfactant and its preparation method and application

Technical field

The invention belongs to the technical field of coal seam fracturing, and specifically relates to a surfactant and its preparation method and application.

Background technique

Hydraulic fracturing technology is an effective means to increase production in low-permeability oil and gas reservoirs, in which fracturing fluid, as its core component, is called the "blood" of hydraulic fracturing technology. At present, the commonly used fracturing fluid in coal seams is active water fracturing fluid, which has low viscosity, high friction, large filter loss, and difficult to control fractures. Although the vegetable gum fracturing fluid developed later has good viscosity, it has complex formulas and Problems such as difficulty in gel breaking and high damage; while clean fracturing fluids using surfactants as thickeners have the advantages of both types of fracturing fluids. They have good viscoelasticity and are less harmful to the formation. However, currently Conventional clean fracturing fluid systems have complex formulas, poor adjustability, and poor compatibility with formation water. Therefore, it is necessary to further optimize the structure of traditional surfactants to improve the performance of current fracturing fluids.

In 2016, Qi Lisa (Qi Lisa. Research on clean fracturing fluid suitable for low-temperature coalbed methane reservoirs [J]. Petrochemical Applications, 2016, 35(05):42-44+48.) conducted indoor experiments to Water, thickener 1631, micelle accelerator NaSal, KCI, and pH regulator KOH were mixed in a certain proportion to prepare a viscoelastic colloid. This system has shear stability, low filter loss, and low friction. After adding the gel breaker, it can lose its sand-carrying capacity in 1.5 h-3 h, and the gel can be broken completely without residue within 6 h-8 h. However, the formula is relatively complex, which increases the difficulty of on-site preparation.

Patent CN201810997938.3 relates to coalbed methane water well hydraulic fracturing technology, specifically a fracturing fluid for coalbed methane wells and its preparation method. The raw materials of fracturing fluid include pH adjuster, clay stabilizing (anti-swelling) agent, surfactant, bactericide and surface water solution. The mass proportion of pH adjuster is 0.015%-0.075%, and the mass proportion of clay stabilizer is The mass proportion is 1%-4%, the mass proportion of surfactant is 0.05%-0.1%, the mass proportion of fungicide is 0.05%-0.1%, and the rest is surface water original solution. This invention requires first using a pH adjuster to remove precipitated ions generated by the reaction between the original fracturing fluid and the formation water, thereby improving the compatibility of the surfactant and the formation water. The overall steps are cumbersome and the fracturing fluid formula is complex.

Patent CN202110776335.2 discloses a fracturing fluid and its preparation method and application, which belongs to the technical field of coal seam water injection. The fracturing fluid in this invention is composed of surfactants, nanomaterials, clay stabilizers and water. The system can be well immersed in the coal body, interact with the coal body, and increase the wettability of the coal body. However, this system There are many types of additives, and they need to be mixed at 50°C during preparation, which increases the complexity of on-site liquid preparation.

Contents of the invention

In order to solve the problem in the existing technology that when preparing clean fracturing fluid for coal seams, the salinity of the water medium used is strict, it is difficult to use formation water to prepare the fluid, and the fracturing fluid formula is complex, on-site fluid preparation is difficult, and the application is flexible. Problems such as poor stability and unadjustable performance. The present invention provides a surfactant and its preparation method and application. By synthesizing a new betaine-type surfactant with a benzene ring tail chain and a carboxyl head group, a single component is achieved. Preparation of variable viscosity clean fracturing fluid with good salt resistance. The fracturing fluid can achieve continuous viscosity adjustment by changing the concentration of surfactant, thereby effectively improving the flexibility of fracturing fluid application.

In order to achieve the above objects, the present invention provides the following technical solutions:

One of the technical solutions of the present invention: a surfactant with a chemical structural formula as shown in formula (1):

(1).

The second technical solution of the present invention: the preparation method of the above-mentioned surfactant includes the following steps:

(1) Mix p-hydroxybenzyl alcohol and tetradecane bromide in organic solvent A, react, filter, evaporate the solvent, and wash the crude product to obtain p-tetradecyloxybenzyl alcohol; the reaction route is: :

;

Among them, K ₂ CO ₃ is added to maintain the system as alkaline.

(2) Add phosphorus tribromide to the dichloromethane solution of p-tetradecyloxybenzyl alcohol obtained in step (1), extract after the reaction is completed, and evaporate the solvent from the obtained organic layer to obtain p-tetradecyl Oxybenzyl bromide; the reaction route is:

;

(3) Mix p-tetradecyloxybenzyl bromide and dimethylamine obtained in step (2) in organic solvent B, react, then wash and separate, and evaporate the solvent from the obtained organic layer to obtain p-tetradecyl Oxybenzyldimethylamine; the reaction route is:

;

(4) Mix p-tetradecyloxybenzyldimethylamine and chloroacetate obtained in step (3) in a solvent and react, then evaporate the solvent to dryness, and wash the obtained product to obtain p-tetradecyloxybenzyldimethylamine. Benzyldimethylbetaine is the surfactant, and the reaction route is:

.

Further, in step (1), the mass ratio of p-hydroxybenzyl alcohol and tetradecane bromide is 5: (10-14), preferably 5:12; the organic solvent A includes acetone; the reaction is carried out in an alkali It is carried out in a sexual environment, and the time is 10 to 14 hours, preferably 12 hours; petroleum ether is used for the washing.

Further, in step (2), in the dichloromethane solution of p-tetradecyloxybenzyl alcohol, the concentration of p-tetradecyloxybenzyl alcohol is 6 to 7.5g/mL; the tribromo The mass ratio of phosphorus to the methylene chloride solution of p-tetradecyloxybenzyl alcohol is (1.5~2.5):1, preferably 2:1; the reaction temperature is 32~38°C, and the time is 0.5 ~1.5h, preferably 1h at 36°C; dichloromethane is used for the extraction.

Further, in step (3), the mass ratio of p-tetradecyloxybenzyl bromide and dimethylamine is 5: (2-4), preferably 5:3; the organic solvent B is diethyl ether and A mixture of ethanol in a volume ratio of 1: (1-1.5); the reaction temperature is 25-30°C and the time is 20-30h, preferably 24h at 25°C; the washing is specifically done by using an alkaline solution in sequence and water for washing.

Further, in step (4), the chloroacetate includes sodium chloroacetate; the mass ratio of the p-tetradecyloxybenzyldimethylamine and chloroacetate is 2: (0.5-1), Preferably, it is 2:0.7; the solvent is an ethanol aqueous solution composed of ethanol and water according to the volume of (3-5):1; the reaction time is 8-10h; the washing is carried out by sequentially using diethyl ether and ethyl acetate. .

The third technical solution of the present invention: application of the above-mentioned surfactant in preparing coal seam fracturing fluid.

The fourth technical solution of the present invention: a coal seam fracturing fluid, including water and the above-mentioned surfactant.

Further, the mass percentage of the surfactant in the coal seam fracturing fluid is 0.35 to 2.35%.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The surfactant provided by the present invention can be directly added with water to obtain a clean fracturing fluid, making the clean fracturing fluid system single-component and simple to prepare; and by changing the surfactant concentration, the viscosity of the clean fracturing fluid can be made at 4 mPa Continuously adjustable within ∙s-87 mPa∙s;

(3) The clean fracturing fluid prepared with the surfactant provided by the invention has good salt resistance, among which 2.35 wt% p-tetradecyloxybenzyldimethylbetaine prepared with 48000mg/L simulated formation water The viscosity of the solution can reach 113 mPa∙s at 25°C and 170 s ^-1 .

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the drawings of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is the one-dimensional hydrogen nuclear magnetic spectrum of p-tetradecyloxybenzyldimethylbetaine prepared in Example 1;

Figure 2 shows the effect of p-tetradecyloxybenzyldimethylbetaine concentration on the viscosity of surfactant solution;

Figure 3 shows the evaluation results of the damage performance of the gel breaker prepared with the surfactant solution of Example 6 to the core.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention. It should be understood that the terms used in the present invention are only used to describe particular embodiments and are not intended to limit the present invention.

In addition, for numerical ranges in the present invention, it should be understood that every intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or value intermediate within a stated range and any other stated value or value intermediate within a stated range is also included within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents relate. In the event of conflict with any incorporated document, the contents of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and changes can be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to the skilled person from the description of the invention. The specification and examples of the present invention are exemplary only.

The words "includes", "includes", "has", "contains", etc. used in this article are all open terms, which mean including but not limited to.

Example 1

Preparation of surfactant-to-tetradecyloxybenzyldimethylbetaine, the steps are as follows:

(1) Mix 25 g of p-hydroxybenzyl alcohol and 60 g of tetradecane bromide in acetone, add 30g of K ₂ CO ₃ to make the system alkaline, reflux for 12 hours, filter and evaporate the solvent to dryness, and use petroleum The crude product was washed with ether to obtain p-tetradecyloxybenzyl alcohol with a yield of 67.9%;

(2) Add p-tetradecyloxybenzyl alcohol obtained in step (1) into dichloromethane to obtain a methylene chloride solution of p-tetradecyloxybenzyl alcohol with a concentration of 7.5g/mL; add 30 g Phosphorus tribromide was dropped into 15 g of p-tetradecyloxybenzyl alcohol in methylene chloride, reacted at 36°C for 1 hour, and then quenched with sodium bicarbonate. The organic layer was extracted with methylene chloride and evaporated. The dry solvent gave p-tetradecyloxybenzyl bromide with a yield of 82.7%;

(3) Mix 10 g of p-tetradecyloxybenzyl bromide obtained in step (2) and 6 g of dimethylamine in a mixed solvent composed of diethyl ether and ethanol (the volume ratio of diethyl ether and ethanol is 1:1.2). , reacted at room temperature (25°C) for 24 hours, washed with sodium hydroxide solution and deionized water in sequence, separated and evaporated the organic layer solvent to obtain p-tetradecyloxybenzyldimethylamine, with a yield of 78.9% ;

(4) Mix 10 g of p-tetradecyloxybenzyldimethylamine obtained in step (3) and 3.5 g of sodium chloroacetate in 25 mL of aqueous ethanol solution (the volume ratio of ethanol to water is 4:1) and then reflux. After 9 hours, the solvent was evaporated to dryness and washed with diethyl ether and ethyl acetate in sequence to obtain p-tetradecyloxybenzyldimethylbetaine with a yield of 100%. Its one-dimensional hydrogen magnetic spectrum is shown in Figure 1.

Example 2

Add 0.35 g of p-tetradecyloxybenzyldimethylbetaine obtained in Example 1 to 99.65 g of water, and stir evenly at room temperature to obtain a 0.35 wt% surfactant solution.

Example 3

Add 0.85 g of p-tetradecyloxybenzyldimethylbetaine obtained in Example 1 to 99.15 g of water, and stir evenly at room temperature to obtain a 0.85 wt% surfactant solution.

Example 4

Add 1.35 g of p-tetradecyloxybenzyldimethylbetaine obtained in Example 1 to 98.65 g of water, and stir evenly at room temperature to obtain a 1.35 wt% surfactant solution.

Example 5

Add 1.85 g of p-tetradecyloxybenzyldimethylbetaine obtained in Example 1 to 98.15 g of water, and stir evenly at room temperature to obtain a 1.85 wt% surfactant solution.

Example 6

Add 2.35 g of p-tetradecyloxybenzyldimethylbetaine obtained in Example 1 to 97.65 g of water, and stir evenly at room temperature to obtain a 2.35 wt% surfactant solution.

Effect verification

Performance tests were conducted on the surfactant solutions prepared in Examples 2 to 6 of the present invention in accordance with the standards SY/T 6376-2008 "General Technical Conditions for Fracturing Fluids" and SY/T5107-2016 "Performance Evaluation Method of Water-Based Fracturing Fluids". The result is as follows:

1. Viscosity adjustability test

Use a rheometer to test the viscosity of the surfactant solutions prepared in Examples 2 to 6 at 25°C and 170 s ^-1 . The results are shown in Table 1 and Figure 2:

Table 1

Figure 2 shows the effect of the concentration of tetradecyloxybenzyldimethylbetaine on the viscosity of the solution. It can be seen from Figure 1 that the viscosity of the clean fracturing fluid can be made at 4 mPa∙s by changing the surfactant concentration. Continuously adjustable within -87 mPa∙s.

2. Anti-swelling performance and gel breaking performance test

The anti-swelling performance and gel-breaking performance of the surfactant solution in Example 6 were evaluated, in which a coal sample was used to examine its anti-swelling performance (the mass ratio of coal sample to surfactant solution was 1:20); and because of the hydrocarbon When small molecules encounter the surfactant fracturing fluid, they will solubilize into the system, disintegrate its network structure, and finally achieve gel breaking. Therefore, the gel breaking performance of the surfactant solution prepared in Example 6 was investigated by adding kerosene ( The mass ratio of kerosene to surfactant solution is 30:70, that is, the amount of kerosene added is 30wt%), and the high-temperature and high-pressure core displacement device was used to test the damage, anti-swelling performance and The gel-breaking performance test results are shown in Table 2, and the damage performance evaluation results of the gel-breaking fluid to the core are shown in Figure 3.

Table 2

It can be seen from Table 2 that the surfactant solution prepared in Example 6 has good anti-swelling properties, and the viscosity of its gel-breaking liquid is lower than 5 mPa∙s. There is no insoluble residue after gel-breaking. It can be calculated from the data in Figure 3 It was concluded that the damage caused by the gel-breaking liquid to the coal rock was only 14.8%. In addition, the system has a lower surface tension after gel breaking, which can reduce the risk of severe "liquid resistance" effect and promote the backflow of the gel-breaking liquid.

3. Resistance to mineralization

Dissolve quantitative amounts of sodium carbonate, sodium chloride, sodium sulfate, sodium bicarbonate, calcium chloride, magnesium chloride, and potassium chloride with an appropriate amount of deionized water and transfer them to a 1 L volumetric flask to make up to 2000 mg/L. , 8000 mg/L, 22000 mg/L and 48000 mg/L simulated formation water with four salinities, take 2.35 g of p-tetradecyloxybenzyldimethylbetaine obtained in Example 1 and add 97.65g of the above Simulated formation water with different degrees of salinity was stirred evenly at room temperature to obtain four 2.35wt% surfactant solutions, respectively expressed as: V ₂₀₀₀ , V ₈₀₀₀ , V ₂₂₀₀₀ and V ₄₈₀₀₀ .

The viscosity of the above four different surfactant solutions was tested using a rheometer at 25°C and 170 s ^-1 . The results are shown in Table 3.

table 3

It can be seen from Table 3 that within the test range, as the salinity increases, the viscosity of the system shows an upward trend, indicating that it is feasible to use formation water to prepare the fracturing fluid.

Example 7

Preparation of surfactant-to-tetradecyloxybenzyldimethylbetaine, the steps are as follows:

(1) Mix 25 g of p-hydroxybenzyl alcohol and 50 g of tetradecane bromide in acetone, and add 30g of K ₂ CO ₃ to make the system alkaline, reflux for 10 h, filter and evaporate the solvent to dryness, and use petroleum The crude product is washed with ether to obtain p-tetradecyloxybenzyl alcohol;

(2) Add p-tetradecyloxybenzyl alcohol obtained in step (1) into dichloromethane to obtain a methylene chloride solution of p-tetradecyloxybenzyl alcohol with a concentration of 6g/mL; add 30 g of tritetradecyloxybenzyl alcohol to methylene chloride. Phosphorus bromide was dropped into a dichloromethane solution of 20 g of p-tetradecyloxybenzyl alcohol, reacted at 32°C for 1.5 hours, and then quenched with sodium bicarbonate. The organic layer was extracted with dichloromethane and evaporated to dryness. The solvent gives p-tetradecyloxybenzyl bromide;

(3) Mix 10 g of p-tetradecyloxybenzyl bromide obtained in step (2) and 4 g of dimethylamine in a mixed solvent composed of diethyl ether and ethanol (the volume ratio of diethyl ether and ethanol is 1:1). , reacted at 30°C for 20 hours, washed with sodium hydroxide solution and deionized water in sequence, separated and evaporated the organic layer solvent to obtain p-tetradecyloxybenzyldimethylamine;

(4) Mix 10 g of p-tetradecyloxybenzyldimethylamine obtained in step (3) and 2.5 g of sodium chloroacetate in 25 mL of ethanol aqueous solution (the volume ratio of ethanol to water is 3:1) and then reflux. For 8 hours, the solvent was evaporated to dryness and then washed with diethyl ether and ethyl acetate to obtain p-tetradecyloxybenzyldimethylbetaine.

Example 8

Preparation of surfactant-to-tetradecyloxybenzyldimethylbetaine, the steps are as follows:

(1) Mix 25 g of p-hydroxybenzyl alcohol and 70 g of tetradecane bromide in acetone, and add 30 g of K ₂ CO ₃ to make the system alkaline, reflux for 14 hours, filter and evaporate the solvent to dryness, and use petroleum The crude product is washed with ether to obtain p-tetradecyloxybenzyl alcohol;

(2) Add p-tetradecyloxybenzyl alcohol obtained in step (1) into dichloromethane to obtain a methylene chloride solution of p-tetradecyloxybenzyl alcohol with a concentration of 6.5g/mL; add 37.5 g Phosphorus tribromide was dropped into a dichloromethane solution of 15 g of p-tetradecyloxybenzyl alcohol, reacted at 38°C for 0.5 h, and then quenched with sodium bicarbonate. The organic layer was extracted with dichloromethane and evaporated. Drying the solvent gives p-tetradecyloxybenzyl bromide;

(3) Mix 10 g of p-tetradecyloxybenzyl bromide obtained in step (2) and 8 g of dimethylamine in a mixed solvent composed of diethyl ether and ethanol (the volume ratio of diethyl ether and ethanol is 1:1.5). , reacted at 28°C for 30 hours, washed with sodium hydroxide solution and deionized water in sequence, separated and evaporated the organic layer solvent to obtain p-tetradecyloxybenzyldimethylamine;

(4) Mix 10 g of p-tetradecyloxybenzyldimethylamine obtained in step (3) and 5.0 g of sodium chloroacetate in 25 mL of aqueous ethanol solution (the volume ratio of ethanol to water is 5:1) and then reflux. After 10 h, the solvent was evaporated to dryness and then washed with diethyl ether and ethyl acetate to obtain p-tetradecyloxybenzyldimethylbetaine.

The p-tetradecyloxybenzyldimethylbetaine prepared in Examples 7 and 8 was prepared into a surfactant solution according to the method of Examples 2 to 6, and its performance was tested according to the above effect verification method. , the results are not significantly different from the performance of the surfactant solutions obtained in Examples 2 to 6, and will not be described again here.

The above are only preferred specific embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Any person familiar with the technical field shall, within the technical scope disclosed in the present invention, according to the technical solutions of the present invention and Any equivalent substitution or change of the inventive concept shall be covered by the protection scope of the present invention.

Claims (9)

1. A surfactant, which is characterized in that the chemical structural formula of the surfactant is shown as a formula (1):

（1）。

2. the method for preparing the surfactant according to claim 1, comprising the steps of:

(1) Mixing p-hydroxybenzyl alcohol and bromotetradecane in an organic solvent A, reacting, filtering, evaporating the solvent, and washing the obtained crude product to obtain p-tetradecyloxybenzyl alcohol;

(2) Adding phosphorus tribromide into the dichloromethane solution of the p-tetradecyloxy benzyl alcohol obtained in the step (1), extracting after the reaction is finished, and evaporating the solvent from the obtained organic layer to obtain p-tetradecyloxy benzyl bromide;

(3) Mixing the para-tetradecyloxy benzyl bromide obtained in the step (2) with dimethylamine in an organic solvent B, reacting, washing, separating, and evaporating the solvent from the obtained organic layer to obtain para-tetradecyloxy benzyl dimethylamine;

(4) And (3) mixing the p-tetradecyloxy benzyl dimethylamine obtained in the step (3) with chloroacetate in a solvent for reaction, evaporating the solvent, and washing the obtained product to obtain the p-tetradecyloxy benzyl dimethyl betaine, namely the surfactant.

3. The preparation method according to claim 2, wherein in the step (1), the mass ratio of the p-hydroxybenzyl alcohol to the bromotetradecane is 5:10-14; the organic solvent A is acetone; the reaction is carried out in alkaline environment for 10-14 h; the washing adopts petroleum ether.

4. The process according to claim 2, wherein in the step (2), the concentration of p-tetradecyloxybenzyl alcohol in the methylene chloride solution of p-tetradecyloxybenzyl alcohol is 6 to 7.5g/mL; the mass ratio of the phosphorus tribromide to the methylene dichloride solution of the para-tetradecyloxy benzyl alcohol is (1.5-2.5) to 1; the reaction temperature is 32-38 ℃ and the reaction time is 0.5-1.5 h; the extraction was performed with methylene chloride.

5. The preparation method according to claim 2, wherein in the step (3), the mass ratio of the para-tetradecyloxybenzyl bromide to the dimethylamine is 5:2-4; the organic solvent B is a mixture of diethyl ether and ethanol according to the volume ratio of 1:1-1.5; the reaction temperature is 25-30 ℃ and the reaction time is 20-30 h; the washing is specifically to wash sequentially by adopting alkaline solution and water.

6. The method according to claim 2, wherein in the step (4), the chloroacetate is sodium chloroacetate; the mass ratio of the p-tetradecyloxy benzyl dimethylamine to the chloroacetate is 2: (0.5-1); the solvent is ethanol aqueous solution composed of ethanol and water according to the volume of (3-5) to 1; the reaction time is 8-10 h; the washing is carried out by adopting diethyl ether and ethyl acetate in sequence.

7. Use of the surfactant of claim 1 in the preparation of a coal seam fracturing fluid.

8. A coal seam fracturing fluid comprising water and the surfactant of claim 1.

9. The coal seam fracturing fluid of claim 8, wherein the surfactant is present in the coal seam fracturing fluid in an amount of 0.35 to 2.35% by mass.