CN115058238B - A surface-modified nanoparticle high-temperature foam stabilizer and its preparation method and application - Google Patents

Abstract

The invention provides a surface modified nanoparticle high-temperature foam stabilizer, and a preparation method and application thereof. The stabilizer disclosed by the invention is prepared from the following raw materials in percentage by mass: 1.0 to 2.0 percent of lithium magnesium silicate nano particles, 0.01 to 0.05 percent of surface modifier, 0.01 to 0.1 percent of interfacial synergist and the balance of water; the sum of the mass percentages of the raw materials is hundred percent. The surface modified nanoparticle high-temperature foam stabilizer prepared by the invention can greatly improve the stability of high-temperature foam, strengthen the blocking performance of the high-temperature foam and improve the profile control and yield increase effect of the foam under the condition of ensuring a larger foaming volume; and has good temperature resistance and injection performance.

Description

A surface-modified nanoparticle high-temperature foam stabilizer and its preparation method and application

Technical field

The invention belongs to the technical field of oilfield chemistry, and specifically relates to a surface-modified nanoparticle high-temperature foam stabilizer and its preparation method and application.

Background technique

Steam injection is the main way to recover heavy oil. However, due to the low density and low viscosity characteristics of steam and the ubiquitous heterogeneity of the formation, steam overlay and steam channeling phenomena are easily occurred during the steam injection process, which reduces the efficiency of steam. The swept volume affects the development effect of steam injection. The foam control and displacing agent has the selective blocking ability of "blocking large ones but not small ones, blocking water but not oil". While blocking the steam channeling channel, it can also control the steam mobility, which can greatly increase the swept volume of injected steam, and then Improve the steam injection development effect. However, foam is a typical thermodynamically unstable system. Under high temperature conditions, it is easy to undergo liquid drainage, disproportionation and coalescence processes, causing the foam to burst, thereby greatly reducing the foam's ability to adjust, drive and block. Adding foam stabilizers to foaming agents is the main means to improve foam stability. Low-molecular alcohols and high-molecular polymers are often used as foam stabilizers, which can improve foam stability to a certain extent. However, when the temperature Above 150°C, these low-molecular alcohols and high-molecular polymers are easily decomposed by heat, and their foam-stabilizing effect no longer exists.

Inorganic nanoparticles have excellent temperature resistance and have good foam stabilization properties after modification. More and more studies are using nanoparticles as high-temperature foam stabilizers to improve high-temperature foam stability. Chinese patent document CN111253922A provides an in-situ self-generated nanoparticle stable foam system and its preparation and application; it is a nanoparticle foam stabilizing system composed of silicate, biosurfactant alkyl glycoside, and salt water. The foaming volume of this system can reach about 1000 mL; however, the half-life of liquid drainage is only a few minutes, the high-temperature foam is not stable enough, and the blocking ability needs to be improved. Chinese patent document CN104774603A provides a stable foam system based on nanoparticles and Gemini surfactant and its preparation method; it is a foam system composed of nanosilica, Gemini surfactant and water. The foaming volume of this system is less than 300mL, and the foaming volume is small; the high-temperature foam stability is poor. Chinese patent document CN112175600A discloses a new type of foam stabilizer and its preparation method. This foam stabilizer uses silane coupling agent KH550 and alkyl bromide as raw materials. By adjusting the alkyl bromide, it first reacts to generate a coupling agent with hydrophobic groups, and combines the sodium chloroacetate hydrophilic group with the quaternary ammonium group in the previous step. chemical reaction, and then further coupled with silica to form a modified particle with hydrophilic and hydrophobic groups. The modified particles prepared by this invention have excellent dispersion and wettability; however, the liquid half-life is short and the high-temperature foam is not stable enough.

In summary, it is difficult for existing nanoparticles to significantly improve the stability of high-temperature foam while maintaining the foaming volume, and they cannot effectively improve the high-temperature blocking ability of the foam. Therefore, it is of great significance to develop a foam stabilizer that does not affect the foaming volume and can greatly improve the stability of high-temperature foam to improve the effect of high-temperature foam control and flooding.

Contents of the invention

In view of the shortcomings of the existing technology, the present invention provides a surface-modified nanoparticle high-temperature foam stabilizer and its preparation method and application. The surface-modified nanoparticle high-temperature foam stabilizer prepared by the present invention can greatly improve the stability of high-temperature foam, strengthen the blocking performance of high-temperature foam, and improve the effect of foam control and flooding and production increase under the condition of ensuring a larger foaming volume; and has Good temperature resistance and injection performance.

The technical solution of the present invention is as follows:

A surface-modified nanoparticle high-temperature foam stabilizer, which is prepared by including the following mass percentages of raw materials: lithium magnesium silicate nanoparticles 1.0% to 2.0%, surface modifier 0.01% to 0.05%, and interface synergy The agent is 0.01% to 0.1%, and the balance is water; the sum of the mass percentages of each raw material is 100%.

According to the preferred embodiment of the present invention, the stabilizer is prepared from raw materials with the following mass percentages: 1.0% to 1.5% of magnesium lithium silicate nanoparticles, 0.03% to 0.05% of surface modifiers, and 0.05% to 0.1% of interface synergists. , the balance is water; the sum of the mass percentages of each raw material is 100%.

According to the preferred embodiment of the present invention, the lithium magnesium silicate nanoparticles have a trioctahedral layered structure and an average particle size of 30 to 50 nm. The nanoparticles have excellent water dispersibility, tackiness and temperature resistance.

According to the preferred embodiment of the present invention, the surface modifier is one or a combination of two or more of n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine or n-octylamine.

According to the preferred embodiment of the present invention, the interface synergist is one or a combination of two or more of sodium hydroxide, sodium silicate, sodium phosphate, sodium carbonate or sodium metaborate.

The preparation method of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer includes the steps:

Disperse magnesium lithium silicate nanoparticles in water to obtain a magnesium lithium silicate water dispersion system. Add a surface modifier to disperse evenly; then add an interface synergist to adjust the pH to 10.0~11.0. After full reaction and post-processing, the surface modification is obtained. Nanoparticle high temperature foam stabilizer.

According to the preferred method of the present invention, the preparation method of magnesium lithium silicate aqueous dispersion system includes the steps of: adding magnesium lithium silicate nanoparticles into water, stirring at 1000-2000r/min and room temperature for 4-6h, and then leaving it at room temperature for 12-24h. Finally, a uniformly dispersed aqueous dispersion system of magnesium lithium silicate is obtained.

According to the preferred embodiment of the present invention, the dispersion conditions after adding the surface modifier are: stirring at room temperature for 4 to 6 hours, and the stirring rate is 400 to 800 r/min.

According to the preferred embodiment of the present invention, after the surface modifier is added and dispersed evenly, the interface synergist is added under stirring conditions of 400 to 800 r/min.

According to the preferred embodiment of the present invention, the reaction conditions are: leaving the reaction at room temperature for 12 to 24 hours.

According to the preferred method of the present invention, the post-treatment method includes the following steps: the reaction solution obtained after the reaction is vacuum-dried at 50-80°C for 12-24 hours, and then washed with absolute ethanol and distilled water in sequence; repeat the above process 2-4 times, and finally Vacuum dry at 50-80°C for 12-24 hours and grind into powder to obtain a surface-modified nanoparticle high-temperature foam stabilizer.

The application of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer can be used as a foam stabilizer in high-temperature foam systems.

According to the preferred embodiment of the present invention, the foam system includes the following mass percentage of raw materials: 1.0% to 1.5% of surface-modified nanoparticle high-temperature foam stabilizer, 0.5% to 1.0% of foaming agent, and the balance is water; the mass of each raw material The sum of the percentages is one hundred percent.

Preferably, the foaming agent is one or a combination of two or more of sodium α-olefin sulfonate, sodium dodecyl benzene sulfonate or sodium dodecyl sulfonate.

Preferably, the preparation method of the foam system includes the steps of: dispersing surface-modified nanoparticle high-temperature foam stabilizer in water, adding a foaming agent, and obtaining a foam system after uniform dispersion.

Further preferably, the preparation method of the foam system includes the steps of: adding the surface-modified nanoparticle high-temperature foam stabilizer to water, stirring at room temperature for 4 to 8 hours at 1000 to 2000 r/min, and then leaving it at room temperature for 12 to 24 hours; Then, under stirring conditions of 200 to 400 r/min, add a foaming agent, stir and disperse at room temperature for 30 to 60 minutes, and then let stand at room temperature for 12 to 24 hours to obtain a foam system.

The technical features and beneficial effects of the present invention are as follows:

1) The surface-modified nanoparticle high-temperature foam stabilizer provided by the present invention is made of magnesium lithium silicate inorganic nanoparticles with excellent water dispersibility, tackification and temperature resistance. Under the action of the interface synergist, Short-chain alkyl amines are used to neutralize the negative charges on the surface of magnesium lithium silicate particles through electrostatic interaction. Through this electrostatic neutralization, the molecular chains of short-chain alkyl amines can be oriented and arranged, with the hydrophobic end facing outward. , thereby reducing the hydrophilicity of the magnesium lithium silicate particles and achieving the purpose of hydrophobic modification. A small amount of hydrophobic chains are introduced through the electrostatic adsorption of a small amount of short-chain alkylamine, which changes the surface wettability of the nanoparticles from a strongly hydrophilic surface to a weakly hydrophilic surface (contact angle is 60-70°); while the weakly hydrophilic nanoparticles can The formation of irreversible adsorption on the gas-liquid interface can significantly increase the viscosity and interfacial viscoelasticity of the liquid film at the gas-liquid interface, enhance the mechanical strength of the interface liquid film, and thus greatly improve the stability of the foam. The modification method provided by the invention can avoid excessive flocculation of nanoparticles caused by modification of cationic surfactants and adverse effects on particle dispersion and viscosity-increasing properties. The addition of the interface synergist of the present invention is beneficial to the modification of the surface of the magnesium lithium silicate particles by the surface modifier, and is beneficial to promoting the adsorption of the modified particles on the gas-liquid interface, thereby being beneficial to improving the high-temperature stability and control and flooding performance of the foam. .

2) The surface-modified nanoparticle high-temperature foam stabilizer provided by the present invention has excellent foam stabilizing performance, and significantly increases the liquid out half-life and foam half-life of high-temperature foam without affecting the foaming ability of the foaming agent. Greatly improve the stability of high-temperature foam. Its stabilizing principle lies in the fact that short-chain alkylamine surface-modified magnesium lithium silicate nanoparticles can be firmly adsorbed to the air-liquid interface to form a shell-like structure, which greatly improves the mechanical strength of the foam liquid film. At the same time, the nanoparticles in the liquid phase are connected to form a three-dimensional structure. The network structure increases the liquid phase viscosity and further prevents the disproportionation and aggregation of foam, thus greatly improving the stability of high-temperature foam.

3) The surface-modified nanoparticle high-temperature foam stabilizer provided by the present invention has excellent temperature resistance and viscosity-increasing properties, can greatly enhance the control and displacement performance of foam under high temperature conditions above 250°C, and can greatly improve the control and displacement of steam foam. Sealing effect; at the same time, the average particle size of the nanoparticles after surface modification is 100~150nm, which can be suitable for high-temperature foam control and flooding of reservoirs with different permeabilities.

4) The surface-modified nanoparticle high-temperature foam stabilizer provided by the present invention has a simple preparation method, the modified nanoparticles have strong dispersion, and are easy to prepare a water dispersion system. They can be stored and used after modification, and can be prepared and used before production, and have a foam stabilizing effect. will not be affected.

Description of drawings

Figure 1 shows the surface-modified nanoparticles high-temperature foam stabilizer (modified magnesium lithium silicate), magnesium lithium silicate nanoparticles (magnesium lithium silicate) and modifier n-butylamine (modifier) prepared in Example 1 infrared spectrum.

Figure 2 shows the surface-modified nanoparticle high-temperature foam stabilizer (modified magnesium lithium silicate) and magnesium lithium silicate nanoparticles (magnesium lithium silicate) prepared in Example 1, that is, the contact angle before and after modification of magnesium lithium silicate. Change diagram.

Figure 3 is a fluorescence confocal microscope observation image of the stabilized foam after dyeing the surface-modified nanoparticles prepared in Example 1 with a high-temperature foam stabilizer.

Detailed ways

In order to explain the present invention more clearly, specific embodiments of the present invention are now described in detail, but the scope of protection of the present invention is not limited thereto.

The experimental methods used in the following examples are conventional methods unless otherwise specified.

Materials, reagents, etc. used in the following examples can all be obtained from commercial sources unless otherwise specified.

Example 1

A surface-modified nanoparticle high-temperature foam stabilizer, the stabilizer is prepared by including the following mass percentage of raw materials: 1.0% magnesium lithium silicate nanoparticles, 0.03% surface modifier n-butylamine, and interface synergist hydroxide Sodium 0.05%, the balance is water; the sum of the mass percentages of each raw material is 100%.

The lithium magnesium silicate nanoparticles have a trioctahedral layered structure and an average particle size of 30 to 50 nm. The average particle size of the obtained surface-modified nanoparticle high-temperature foam stabilizer is 100-120 nm.

The preparation method of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer is as follows:

At room temperature, add 10g of lithium magnesium silicate nanoparticles to 990g of deionized water, stir at a high speed of 1000r/min for 4 hours, and then let stand for 12 hours to obtain a uniformly dispersed suspension of magnesium lithium silicate. Add 0.03g n-butylamine surface modifier to 99.92g magnesium lithium silicate suspension, stir at room temperature for 4 hours at 400r/min, and then add 0.05g sodium hydroxide interface synergist under stirring conditions of 400r/min. Adjust the pH to 10.0~11.0 and let it stand at room temperature for 12 hours to obtain a modified magnesium lithium silicate aqueous dispersion system. Dry the above water dispersion system in a vacuum drying oven at 50°C for 24 hours, then wash it with absolute ethanol and distilled water in sequence; repeat the above process three times, and finally vacuum dry it at 50°C for 24 hours, and grind it into powder with an agate mortar. A surface-modified nanoparticle high-temperature foam stabilizer was obtained.

The application of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer can be used as a foam stabilizer in high-temperature foam systems.

The foam system includes the following raw material composition in mass percentage: α-olefin sulfonate sodium (C ₁₆ ~ C ₁₈ ) foaming agent, mass fraction 0.5%; surface modified nanoparticle high temperature foam stabilizer, mass fraction 1.0%; The remaining amount is mixed with clean water, and the mass fraction is 98.5%.

The preparation method of the foam system is as follows:

Add 10g of the surface-modified nanoparticle high-temperature foam stabilizer prepared in this example to 990g of deionized water, stir at room temperature for 4 hours at a high speed of 1000 r/min, and then let it stand at room temperature for 12 hours to obtain uniformly dispersed modified silicic acid. Magnesium and lithium water dispersion system. Under stirring at 200r/min, add 0.5g sodium α-olefin sulfonate (C ₁₆ ~ C ₁₈ ) into 99.5g modified magnesium lithium silicate aqueous dispersion system, stir and disperse at room temperature for 30 minutes, then let it stand at room temperature for 12 hours , to obtain the high-temperature foam system.

Figure 1 shows the surface-modified nanoparticles high-temperature foam stabilizer (modified magnesium lithium silicate), magnesium lithium silicate nanoparticles (magnesium lithium silicate) and surface modifier n-butylamine (modifier ) infrared spectrum. As can be seen from Figure 1, the infrared spectrum of the modified magnesium lithium silicate particles has symmetric vibration absorption peaks of methyl and methylene at 2870cm ^-1 , and methyl and methylene appear at 2934cm ^-1 and 2960cm ^-1 respectively. Asymmetric vibration absorption peak of methyl group. The above stretching vibration peak also appears in the infrared spectrum curve of the modifier, but does not appear in the infrared spectrum curve of the unmodified magnesium lithium silicate particle, indicating that the modifier has adsorbed on the surface of the magnesium lithium silicate particle, making The surface of lithium magnesium silicate particles is partially hydrophobic and causes weak aggregation of lithium magnesium silicate particles, which can promote the adsorption of particle aggregates at the gas-liquid interface.

Figure 2 shows the surface-modified nanoparticle high-temperature foam stabilizer (modified magnesium lithium silicate) and magnesium lithium silicate nanoparticles (magnesium lithium silicate) prepared in this example, that is, the contact angle before and after modification of magnesium lithium silicate. Change diagram. Contact angle test method: Use a hydraulic core machine to make core tablets from dry magnesium lithium silicate particles and modified magnesium lithium silicate particles under a pressure of 25MPa, and place the obtained core tablets in a DSA video contact angle measurement After adjusting to the appropriate position, slowly add a drop of distilled water to the observation platform, and use the DSA video contact angle measuring instrument to record and calculate the contact angle. Figure 2 illustrates that the adsorption of the surface modifier on the surface of lithium magnesium silicate changes the contact angle of lithium magnesium silicate from 18° to 66°, indicating that the wettability of the particle surface changes from strongly hydrophilic to weakly hydrophilic. The ability to adsorb to the gas-liquid interface.

Figure 3 is a fluorescence confocal microscope observation image of the stabilized foam after dyeing the surface-modified nanoparticles prepared in this example with a high-temperature foam stabilizer. The test method is as follows: Prepare the modified magnesium lithium silicate particle aqueous dispersion system and the rhodamine B aqueous solution for later use. Add a trace amount of the rhodamine B aqueous solution into the modified magnesium lithium silicate particle aqueous dispersion system under stirring conditions. Stir at room temperature for 4 hours to obtain the desired result. Test liquid. The liquid to be tested is centrifuged, washed, and dried to obtain modified magnesium lithium silicate particles adsorbed with rhodamine B. The obtained particles are used to prepare a foaming solution according to the method of this example, and then a Waring Blender high-speed stirring cup is used at room temperature. Stir at 3000r/min for 60s to generate foam. Use a sampling gun to place a small amount of foam on the slide, and slowly place the coverslip to prepare the sample. Observe the prepared sample under a fluorescence confocal microscope, adjust the magnification and fluorescence intensity, and save the image of the experimental phenomenon observed through the window. Figure 3 further confirms the above conclusion. The dyed modified magnesium lithium silicate particles are distributed in the foam liquid film, proving that the modified magnesium lithium silicate can be firmly adsorbed to the gas-liquid interface to form a structure and enhance the strength of the gas-liquid-liquid film. , greatly improving foam stability.

Example 2

A surface-modified nanoparticle high-temperature foam stabilizer, which is prepared by including the following mass percentages of raw materials: 1.2% magnesium lithium silicate nanoparticles, 0.04% modifier n-hexylamine, and 0.08% interface synergist sodium carbonate. , the balance is water; the sum of the mass percentages of each raw material is 100%.

The lithium magnesium silicate nanoparticles have a trioctahedral layered structure and an average particle size of 30 to 50 nm. The average particle size of the obtained surface-modified nanoparticle high-temperature foam stabilizer is 120 to 140 nm.

The preparation method of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer is the same as in Example 1.

The application of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer can be used as a foam stabilizer in high-temperature foam systems.

The foam system includes the following mass percentage of raw materials: sodium dodecylbenzene sulfonate foaming agent, mass fraction 0.8%; surface modified nanoparticle high temperature foam stabilizer, mass fraction 1.2%; the balance is mixed with water. , the quality score is 98%.

The preparation method of the foam system is the same as in Example 1.

Example 3

A surface-modified nanoparticle high-temperature foam stabilizer, the stabilizer is prepared by including the following mass percentage of raw materials: 1.5% magnesium lithium silicate nanoparticles, 0.05% surface modifier n-octylamine, and interface synergist metaboric acid Sodium 0.1%, the balance is water; the sum of the mass percentages of each raw material is 100%.

The lithium magnesium silicate nanoparticles have a layered structure and an average particle size of 30 to 50 nm; the obtained surface-modified nanoparticle high-temperature foam stabilizer has an average particle size of 130 to 150 nm.

The preparation method of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer is the same as in Example 1.

The application of the above-mentioned surface-modified nanoparticle high-temperature foam stabilizer can be used as a foam stabilizer in high-temperature foam systems.

The foam system includes the following mass percentage of raw materials: sodium dodecyl sulfonate foaming agent, mass fraction 1.0%; surface-modified nanoparticle high temperature foam stabilizer, mass fraction 1.5%; the balance is mixed with water. The quality fraction is 97.5%.

The preparation method of the foam system is the same as in Example 1.

Comparative example 1

The unmodified magnesium lithium silicate reinforced foam system includes the following raw material composition in mass percentage: α-olefin sulfonate sodium (C ₁₆ ~ C ₁₈ ) foaming agent, mass fraction 0.5%; stabilizer unmodified magnesium silicate Lithium nanoparticles, the mass fraction is 1.0%; the balance is mixed with water, the mass fraction is 98.5%.

The lithium magnesium silicate nanoparticles have a layered structure and an average particle size of 30 to 50 nm.

The preparation method of the magnesium lithium silicate reinforced foam system is the same as in Example 1.

Comparative example 2

A foam stabilizer, which is prepared from raw materials with the following mass percentages: 1.0% magnesium lithium silicate nanoparticles, 0.03% surface modifier cetyltrimethylammonium bromide, and interface synergist hydrogen Sodium oxide 0.05%, the balance is water; the sum of the mass percentages of each raw material is 100%.

The lithium magnesium silicate nanoparticles have a layered structure with an average particle size of 30 to 50 nm, and the resulting surface-modified nanoparticle high-temperature foam stabilizer has a particle size of 1.0 μm to 1.5 μm.

The preparation method of the above-mentioned foam stabilizer is the same as in Example 1.

The application of the above-mentioned foam stabilizer is used as a foam stabilizer in high-temperature foam systems.

The foam system includes the following raw material composition in mass percentage: foaming agent sodium α-olefin sulfonate (C ₁₆ ~ C ₁₈ ), mass fraction 0.5%; surface-modified nanoparticle high-temperature foam stabilizer, mass fraction 1.0%; The remaining amount is mixed with clean water, and the mass fraction is 98.5%.

The preparation method of the foam system is the same as in Example 1.

Comparative example 3

A foam stabilizer, which is prepared from raw materials with the following mass percentages: 1.0% magnesium lithium silicate nanoparticles, 0.1% surface modifier n-butylamine, 0.05% interface synergist sodium hydroxide, and the balance is water; the sum of the mass percentages of each raw material is 100%.

The lithium magnesium silicate nanoparticles have a trioctahedral layered structure with an average particle size of 30 to 50 nm, and the resulting surface-modified nanoparticle high-temperature foam stabilizer has an average particle size of 800 to 1000 nm.

The preparation method of the above-mentioned foam stabilizer is the same as in Example 1.

The application of the above-mentioned foam stabilizer is used as a foam stabilizer in high-temperature foam systems.

The foam system includes the following raw material composition in mass percentage: α-olefin sulfonate sodium (C ₁₆ ~ C ₁₈ ) foaming agent, mass fraction 0.5%; surface modified nanoparticle high temperature foam stabilizer, mass fraction 1.0%; The remaining amount is mixed with clean water, and the mass fraction is 98.5%.

The preparation method of the foam system is the same as in Example 1.

Comparative example 4

A foam stabilizer, which is prepared from raw materials with the following mass percentages: 1.0% nano bentonite, 0.03% surface modifier n-butylamine, 0.05% interface synergist sodium hydroxide, and the balance is water; each The sum of raw material mass percentages is one hundred percent.

The preparation method of the above-mentioned foam stabilizer is the same as in Example 1.

The application of the above-mentioned foam stabilizer is used as a foam stabilizer in high-temperature foam systems.

The foam system includes the following raw material composition in mass percentage: α-olefin sulfonate sodium (C ₁₆ ~ C ₁₈ ) foaming agent, mass fraction 0.5%; surface modified nanoparticle high temperature foam stabilizer, mass fraction 1.0%; The remaining amount is mixed with clean water, and the mass fraction is 98.5%.

The preparation method of the foam system is the same as in Example 1.

Test example 1

Research objects: foam stabilizers and foam systems prepared in Examples 1-3 and Comparative Examples 1-4.

(1) High-temperature foam performance evaluation: Disperse the surface-modified nanoparticle high-temperature foam stabilizer prepared in Examples 1-3 and the stabilizer in Comparative Examples 1-4 respectively in water to prepare a water dispersion system with a mass concentration of 2.0% . The above water dispersion system was sealed in a high-temperature aging kettle, placed in a high-temperature roller heating furnace at 250°C for thermal aging treatment for 24 hours, and then naturally cooled to room temperature after being taken out. Use the aged nanoparticles as stabilizers to prepare a foam system according to the preparation methods of the foam systems in Examples 1-3 and Comparative Examples 1-4. Stir the above-mentioned results using the Waring Blender stirring method at 3000r/min for 60s at room temperature. The foam performance of the system, the experimental results are shown in Table 1.

(2) Evaluation of high-temperature blocking performance of the foam system: Use the resistance factor as an index to evaluate the blocking performance of the foam system. The larger the resistance factor, the better the blocking performance of the foam. In the experiment, a sand-filled pipe model with an inner diameter of 25 mm, a length of 30 cm, and a permeability of 3000 mD was used to simulate the formation, and the experimental temperature was 250°C. Measurement of resistance factor: simultaneously inject water and nitrogen at 1 mL·min ^-1 and record the pressure; simultaneously inject the foam system solution and nitrogen at a gas-to-liquid volume ratio of 1:1 and record the pressure; the resistance factor is the foam driving pressure difference and the gas-water mixed injection pressure. The difference ratio is used to calculate the resistance factor. The experimental results are shown in Table 1.

Table 1 High-temperature foam performance and high-temperature blocking performance of the stabilizers in Examples 1-3 and Comparative Examples 1-4

sample Bubble volume/mL Liquid eluate half-life/min Foam half-life/h resistance factor Example 1 635 278 26 60.3 Example 2 620 336 33 71.4 Example 3 605 384 39 85.6 Comparative example 1 620 76 18 42.6 Comparative example 2 615 61 16 35.9 Comparative example 3 580 58 20 36.4 Comparative example 4 610 41 15 27.3

By comparing the foam parameters in Examples 1-3 and Comparative Examples 1-4, it was found that compared to the unmodified magnesium lithium silicate in Comparative Example 1, Examples 1-3 used short-chain alkylamine to modify the magnesium lithium silicate nanoparticles. After particle surface modification, the liquid drainage half-life of the high-temperature foam system was significantly increased by 5 to 9 times, indicating that the highly hydrophilic lithium magnesium silicate particles were modified to become partially hydrophobic and caused weak aggregation of the lithium magnesium silicate particles, thereby promoting the particle The aggregates form irreversible adsorption on the gas-liquid interface, which greatly increases the mechanical strength of the foam liquid film, effectively prevents the disproportionation and aggregation of the foam, and thus significantly improves the stability of the high-temperature foam; at the same time, it can be seen from the foam high-temperature resistance factor data in Table 1 , the resistance factor of the foam system of Examples 1-3 at 250°C is significantly greater than that of Comparative Examples 1-4, indicating that under the synergistic effect of the surface modifier and the interface synergist, the modified magnesium lithium silicate particles at the optimal concentration Stable foam has excellent high-temperature blocking performance and can significantly block high-temperature steam; the surface-modified magnesium lithium silicate high-temperature foam stabilizer provided by the present invention can greatly improve the stability of foam under high-temperature conditions, and can Strengthen high-temperature foam control and sealing capabilities.

Comparative Example 2 uses the cationic surfactant cetyltrimethylammonium bromide to modify the surface of magnesium lithium silicate nanoparticles. Although it can also be adsorbed on the surface of magnesium lithium silicate nanoparticles through electrostatic interaction, it cannot achieve The optimal foam-stabilizing contact angle is 60-70°. The foam stability of the nanoparticles in Comparative Example 2 is also reduced. At the same time, the cationic surfactant adsorbs the negatively charged magnesium lithium silicate particles, causing the nanoparticles to easily flocculate. , causing the particle size to increase sharply, limiting its injection capability. Comparative Example 3 uses a higher concentration of modifier to modify the magnesium lithium silicate nanoparticles. The results show that the modified nanoparticles have a sharp decrease in foam stabilization ability and a sharp increase in particle size, resulting in a decrease in the foam's high-temperature blocking ability. sharply reduced. Comparative Example 4 uses surface-modified nano-bentonite as a high-temperature foam stabilizer, and the foam stabilizing effect and flooding and blocking effect are also significantly worse.

Therefore, surface-modified nanoparticles composed of magnesium lithium silicate particles, surface modifiers and interface synergists are the best high-temperature foam stabilizers, which can significantly improve the high-temperature stability of the foam system and the high-temperature flooding and blocking ability. Improving the high-temperature foam control and flooding effect has good application prospects.

Claims (8)

1. A surface-modified nanoparticle high-temperature foam stabilizer, characterized in that the stabilizer is prepared by including the following mass percentages of raw materials: lithium magnesium silicate nanoparticles 1.0% to 2.0%, surface modifier 0.01% to 0.05%, interface synergist 0.01% to 0.1%, the balance is water; the sum of the mass percentages of each raw material is 100%; The lithium magnesium silicate nanoparticles have a trioctahedral layered structure with an average particle size of 30 to 50 nm; the surface modifier is n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine or n-octylamine. One or a combination of two or more; the interface synergist is one or a combination of two or more of sodium hydroxide, sodium silicate, sodium phosphate, sodium carbonate or sodium metaborate. 2. The surface-modified nanoparticle high-temperature foam stabilizer according to claim 1, characterized in that the stabilizer is prepared by including the following mass percentage of raw materials: lithium magnesium silicate nanoparticles 1.0% to 1.5%, surface modified The additive is 0.03% to 0.05%, the interface synergist is 0.05% to 0.1%, and the balance is water; the sum of the mass percentages of each raw material is 100%. 3. The preparation method of surface-modified nanoparticle high-temperature foam stabilizer as claimed in any one of claims 1-2, including the steps: Disperse magnesium lithium silicate nanoparticles in water to obtain a magnesium lithium silicate water dispersion system. Add a surface modifier to disperse evenly; then add an interface synergist to adjust the pH to 10.0~11.0. After full reaction and post-processing, the surface modification is obtained. Nanoparticle high temperature foam stabilizer. 4. The preparation method of surface-modified nanoparticle high-temperature foam stabilizer according to claim 3, characterized in that it includes one or more of the following conditions: i. The preparation method of magnesium lithium silicate aqueous dispersion system includes the steps: add magnesium lithium silicate nanoparticles into water, stir at 1000-2000r/min and room temperature for 4-6 hours, and then let stand at room temperature for 12-24 hours to obtain dispersion. Uniform magnesium lithium silicate water dispersion system; ii. The dispersion conditions after adding surfactant are: stirring at room temperature for 4 to 6 hours, and the stirring rate is 400 to 800r/min; iii. After adding the surface modifier and dispersing it evenly, add the interface synergist under stirring conditions of 400~800r/min; iv. The reaction conditions are: let the reaction stand at room temperature for 12 to 24 hours; v. The post-treatment method includes the following steps: the reaction solution obtained after the reaction is dried under vacuum at 50-80°C for 12-24 hours, and then washed with absolute ethanol and distilled water in sequence; repeat the above process 2-4 times, and finally pass through 50-80°C Dry under vacuum conditions for 12 to 24 hours and grind it into powder to obtain a surface-modified nanoparticle high-temperature foam stabilizer. 5. The application of surface-modified nanoparticles as a high-temperature foam stabilizer according to any one of claims 1-2, as a foam stabilizer in high-temperature foam systems. 6. Application of surface-modified nanoparticle high-temperature foam stabilizer according to claim 5, characterized in that the foam system includes the following mass percentage of raw materials: surface-modified nanoparticle high-temperature foam stabilizer 1.0% to 1.5% , foaming agent 0.5% ~ 1.0%, the balance is water; the sum of the mass percentages of each raw material is 100%. 7. The application of surface-modified nanoparticle high-temperature foam stabilizer according to claim 6, characterized in that it includes one or more of the following conditions: i. The foaming agent is one or a combination of two or more of sodium α-olefin sulfonate, sodium dodecyl benzene sulfonate or sodium dodecyl sulfonate; ii. The preparation method of the foam system includes the steps of: dispersing the surface-modified nanoparticle high-temperature foam stabilizer in water, adding a foaming agent, and obtaining a foam system after uniform dispersion. 8. Application of the surface-modified nanoparticle high-temperature foam stabilizer according to claim 7, characterized in that the preparation method of the foam system includes the steps of: adding the surface-modified nanoparticle high-temperature foam stabilizer into water, and adding the surface-modified nanoparticle high-temperature foam stabilizer to water at 1000 to Stir at room temperature for 4 to 8 hours at 2000 r/min, then let stand at room temperature for 12 to 24 hours; then add foaming agent at room temperature at 200 to 400 r/min, stir and disperse for 30 to 60 minutes at room temperature, and then let stand at room temperature for 12 to 24 hours. , get the foam system.