CN114736664B - Nanometer titanium dioxide solid particle emulsifier and preparation method thereof - Google Patents

Abstract

The invention provides a nano titanium dioxide solid particle emulsifier and a preparation method thereof, and the nano titanium dioxide solid particle emulsifier is prepared by the method comprising the following steps: dissolving titanium dioxide in absolute ethyl alcohol, and performing ultrasonic treatment to obtain dispersion; adding a phthalate coupling agent into the dispersion liquid for chemical grafting; heating and stirring to react for a period of time, adding a certain amount of bromoalkane, and heating and stirring for a certain period of time; and after heating and stirring are finished, carrying out suction filtration and drying to obtain the nano oleophylic titanium dioxide solid particle emulsifier. The nano-emulsifier can form stable water-in-oil emulsion through the shearing action of stratum under the condition of 10-80% of water saturation of oil deposit, the viscosity of the emulsion is 1.5-22 times of the viscosity of crude oil, the viscosity of the emulsion is in direct proportion to the water saturation of oil deposit in the water saturation range of oil deposit, and the high-viscosity emulsion formed under the high water content condition can block the dominant channel so as to achieve the purposes of controlling the fluidity and stabilizing the drainage and driving front edge and improve the recovery ratio of crude oil.

Description

A kind of nano titanium dioxide solid particle emulsifier and preparation method thereof

technical field

The invention relates to the technical field of oil field chemistry, in particular to a nano-titanium dioxide solid particle emulsifier capable of forming a high internal phase and high viscosity emulsion in a high permeability zone of an oil reservoir and a preparation method thereof.

Background technique

In heterogeneous reservoirs, water flooding will lead to serious fingering phenomenon, that is, due to the heterogeneity in the layer and the difference in oil-water viscosity, the seepage rate of injected water is much faster than that of crude oil. Dominant channels are formed between them, and most of the reservoir is not swept by water after water flooding[ALMANSOUR A O, ALQURAISHI A A, ALHUSSINAN SN, et al. Efficiency pf Enhanced Oil Recovery Using Polymer-ugmented LowSalinity Flooding[J].Journal of Petroleum Exploration & Production Technology, 2017, 7(1): 1149-1158.]. Conventional polymer oil displacement agents may have the problem that the viscosity drops too fast in high-salinity oil reservoirs and need to be used in larger quantities, which increases the cost. At the same time, degradation and failure may occur in high-temperature oil reservoirs; Surfactants are easily adsorbed on the surface of reservoir rocks. At the same time, under the influence of high temperature and high salinity reservoir conditions, the stability of emulsions formed by surfactants is greatly reduced, resulting in a certain degree of limitation in their mobility control ability (Zhao Fangjian, Wang Lijuan, Xia Xiran. Petroleum Geology and Engineering [J], 2014, 28(2):100-103.).

In recent years, researchers have turned their research focus to newer nanomaterials. By modifying nanomaterials, they can be adsorbed at the oil-water interface to form Pickering emulsions. Laboratory and field tests have proved that Pickering emulsions can be injected for a long time, and can remain stable during the flow process, significantly improving oil recovery (Kaminsky RD, Wattenbarger RC, Lederhos J P, et al. Viscous oil recovery using solids-stabilized emulsions[ C]//SPE Annual Technical Conference and Exhibition. Florence: SPE, 2010: SPE No.135284.). Sharma et al. verified that the cumulative recovery rate can be increased by 5% by using the Pickering emulsion prepared with the thickened aqueous phase. (Sharma T, Velmurugan N, Patel P, et al. Use of oil-in-water Pickering emulsion stabilized by nanoparticles in combination with polymer flood for enhanced oil recovery[J]. Pet Sci Technol, 2015, 33(17/18): 1959 -1604.) The stable emulsion type of nanoparticles is mainly affected by the wettability of nanoparticles. When θ<90°, the nanoparticles are hydrophilic and form an O/W emulsion; when θ>90°, The wettability of nanoparticles is lipophilic, forming W/O emulsion (Binks B P, Lumsdon S O. Langmuir, 2000, 16(23), 8622.). However, the type of emulsion is not only related to emulsifiers, but also to the ratio of oil to water. Even lipophilic nanoparticles can still form O/W emulsions when the water content is too high. Therefore, corresponding emulsification is required. agent has a higher phase transition point.

The emulsion formed by nanoparticles solves the problem of poor stability of the emulsion formed by traditional surfactants. It can still maintain stability under some harsh reservoir conditions, and has strong mobility control ability. Therefore, it is widely used in the field of enhanced oil recovery. has very good application potential. At present, there are few studies on the formation of emulsions by single nanoparticles, and most of them use the synergistic effect of surfactants and nanoparticles to form emulsions. At the same time, the phase transition point of the emulsion finally formed is relatively low, and the scope of application is relatively narrow.

Contents of the invention

At least one of the above-mentioned problems is not solved. The present invention proposes a method for preparing a nano-titanium dioxide solid particle emulsifier. The method is relatively simple and can be industrialized. , the viscosity of the formed emulsion is proportional to the water saturation, so as to achieve the purpose of blocking the dominant channel and improving the recovery factor.

In order to achieve the above object, the technical scheme of the present invention is as follows: a preparation method of nano-titanium dioxide solid particle emulsifier, comprising the following steps:

(1) adding nano-titanium dioxide to absolute ethanol and ultrasonically dispersing it to obtain a dispersion;

(2) Adding a phthalate coupling agent into the dispersion liquid and causing it to undergo a coupling reaction with titanium dioxide, in terms of mass percentage, the coupling agent is 0.08 to 0.15 times the mass of the nano titanium dioxide;

(3) Add long-chain bromoalkane dropwise to the reaction solution obtained in step (2), keep stirring during the dropwise addition, after the dropwise addition is completed, react for 10~12h at 60~70°C and keep stirring; In terms of parts, the added amount of the long-chain brominated alkane is 1 to 2 times of the added amount of the nano-titanium dioxide, and after the reaction is completed, it is separated and purified.

One embodiment of the present invention is that in step (1), the titanium dioxide is hydrophilic titanium dioxide with a diameter of 20-100 nm, and the addition amount of the titanium dioxide is 0.02-0.05% of that of the absolute ethanol in terms of mass percentage. times.

One embodiment of the present invention is that in step (1), the preparation time of the dispersion is 20-40 minutes.

One embodiment of the present invention is that in step (2), the reaction temperature is 60-70° C., and the reaction time is 10-12 hours.

One embodiment of the present invention is that in step (2), the titanate coupling agent is isopropyl tris(dioctyl pyrophosphate acyloxy) titanate, bis(dioctyl pyrophosphate acyloxy) One or more of oxy)ethylene titanate, isopropoxy dioleic acid acyloxy (dioctyl phosphate acyloxy) titanate;

One embodiment of the present invention is that in step (3), the long-chain brominated alkane is at least one of dodecane bromide, tetradecane bromide or hexadecane bromide.

One embodiment of the present invention is that the specific operation of the separation and purification is: filter the product after the reaction, and wash it several times with absolute ethanol at the same time. After the separation, vacuum dry the filter cake. After the drying is completed, Just break it up.

Another object of the present invention is to disclose a nano solid particle emulsifier, which is prepared by any of the above methods. The emulsifier can form a water-in-oil emulsion with high viscosity and high internal phase, and at the same time, it can improve oil displacement efficiency.

Beneficial effects: the present invention introduces long-chain alkanes on the surface of titanium dioxide through a coupling agent, thereby synthesizing a nanometer solid particle emulsifier. As an emulsifier, compared with traditional surfactant emulsifiers, it can form a high-viscosity high-internal-phase emulsion; meanwhile, the synthesis method of the invention is simple and industrializable.

Description of drawings

Fig. 1 is the oil-water-solid three-phase contact angle diagram of the nanoparticle emulsified particle after modification;

Fig. 2 is the micrograph that nanoemulsifier forms water-in-oil Pickering emulsion;

Detailed ways

The specific implementation manners of the present invention will be clearly and completely described below in conjunction with examples. Apparently, the described examples are only some embodiments of the present invention, rather than all embodiments.

The present invention will be further described below in conjunction with embodiment:

Example 1

(1) Add 100 g of absolute ethanol and 3 g of hydrophilic titanium dioxide into the reagent bottle, and prepare a dispersion by ultrasonication for 30 minutes.

(2) Add 0.3 g of isopropyl tris(dioctylpyrophosphate acyloxy) titanate (purchased by Nanjing Nengde New Material Technology Co., Ltd.) into the dispersion, and put it in an oil bath at 65°C Heat and stir for 12 hours.

(3) Add 3g of bromododecane dropwise to the dispersion in step 2, shake the reagent bottle during the dropwise addition to ensure that the reaction system is evenly mixed; put it into an oil bath at 65° C. and heat and stir for 12 hours to react After the end, the product is subjected to suction filtration, washing treatment, drying and grinding to obtain the nano solid particle emulsifier S1.

Example 2

(1) Add 100 g of absolute ethanol and 3 g of hydrophilic titanium dioxide into the reagent bottle, and prepare a dispersion by ultrasonication for 30 minutes.

(2) Add 0.3g of bis(dioctylpyrophosphate acyloxy)ethylene titanate (purchased by Nanjing Nengde New Material Technology Co., Ltd.) into the dispersion, put it in an oil bath at 65°C and heat and stirred for 12 hours.

(3) Add 3 g of bromododecane dropwise to the dispersion in step 2, shake the reagent bottle during the dropwise addition to ensure that the reaction system is evenly mixed; put it into an oil bath at 65° C., heat and stir for 12 hours. After the reaction, the product is subjected to suction filtration, washing, drying and grinding to obtain the nano-solid emulsifier S2.

Example 3

(1) Add 100 g of absolute ethanol and 3 g of hydrophilic titanium dioxide into the reagent bottle, and prepare a dispersion by ultrasonication for 30 minutes.

(2) Add 0.3 g of isopropoxy dioleic acid acyloxy (dioctyl phosphate acyloxy) titanate (purchased by Nanjing Nengde New Material Technology Co., Ltd.) into the dispersion liquid, and place it at 65°C Heat and stir in an oil bath for 12 hours.

(3) Add 3 g of hexadecane bromide dropwise to the dispersion in step 2, shake the reagent bottle during the dropwise addition to ensure that the reaction system is evenly mixed; put it into an oil bath at 65° C. to heat and stir for 12 hours. After the reaction, the product is subjected to suction filtration, washing, drying and grinding to obtain the nano-solid emulsifier S3.

Comparative example 1

As a comparison with the prior grafting of long chains on nano-silica via silane coupling agents, this was added as a control group.

(1) Add 100 g of absolute ethanol and 3 g of hydrophilic silicon dioxide to the reagent bottle, and prepare a dispersion by ultrasonication for 30 minutes.

(2) Add 0.3 g of silane coupling agent KH-570 into the dispersion liquid, put it into an oil bath at 65° C., heat and stir for 12 hours.

(3) Add 3 g of tetradecane bromide dropwise to the dispersion in step 2, shake the reagent bottle during the dropwise addition to ensure that the reaction system is evenly mixed; put it into an oil bath at 65° C. to heat and stir for 12 hours. After the reaction is finished, the product is subjected to suction filtration, washing treatment, drying and grinding to obtain the nano solid particle emulsifier D1.

In order to illustrate the effect of the nano solid particle emulsifier prepared in the embodiment of the present invention, its performance test is carried out below.

1. Wettability test

Spread the nanoemulsifier synthesized in Examples 1 to 4 evenly on a quartz glass slide, and measure the oil-water-solid three-phase junction of the nanoemulsifier with a HARHE-SPCA contact angle meter (Haako, China) in a kerosene environment. tentacles, as shown in Figure 1. The contact angles of the nanoemulsifier Examples 1-3 are 135.5°, 132.3°, and 139.7° respectively, which proves the hydrophobicity of the nanoemulsifier. The contact angle of Example 4 as a control group is 109.8°, and its hydrophobicity is slightly worse than that of the nanoemulsifier of the present invention.

2. The ability of nanoemulsifier dispersion to emulsify crude oil (different oil-water ratio)

Add the nanoemulsifiers synthesized in Examples 1 to 4 respectively to the formation water (the formation water type is NaHCO3, and the salinity is 5054mg/L), to prepare nanoemulsifiers with a mass concentration of 0.06%, and ultrasonically dissolve them for 10 minutes to obtain nanoemulsification agent dispersion. In a special measuring cylinder with a measuring range of 50 mL, the nanoemulsifier dispersion and degassed crude oil (viscosity of 84.2 mPa s at 30 °C and shear rate of 7.336 s-1) were mixed according to the water-to-oil volume ratio of 1:9, 2 :8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1 to prepare a total volume of 20mL, mix and seal; then stir in a water bath at 30°C for 30 minutes, Observe the emulsification situation, and calculate the water content of the emulsion in Table 1. It can be observed that the nanoemulsifiers of Examples 1-3 still have good emulsifying properties under the condition of 90% water content, and the water content of the formed emulsion is greater than 80%. And in embodiment 4, the water content of the emulsified liquid formed by the nano silicon dioxide of silane coupling agent grafting long chain can only reach 70%, illustrate that the effect of the emulsified crude oil of the nano solid particle emulsifier of the present invention is better than by The silane coupling agent is grafted with long-chain nano-silica.

After the inventor's analysis, the above phenomenon is mainly due to the fact that the density of nano-silica is lower than that of nano-titanium dioxide. Even after grafting hydrophobic long chains, it still has a slight agglomeration phenomenon. Poor; at the same time, because the titanate coupling agent itself has many hydrophobic groups, after grafting long-chain hydrophobic alkanes, its hydrophobic effect is enhanced, resulting in better final results.

Table 1 Moisture content of emulsion formed by water, nanoemulsifier dispersion and crude oil under different water-to-oil ratio conditions

3. The viscosity of the emulsion formed by the nanoemulsifier dispersion and crude oil (different oil-water ratios)

The nanoemulsifiers synthesized in Examples 1 to 4 were respectively added to the formation water to prepare a nanoemulsifier with a mass concentration of 0.06%, and ultrasonically dissolved for 10 minutes to obtain a nanoemulsifier dispersion. In a special measuring cylinder with a measuring range of 50 mL, the nanoemulsifier dispersion and degassed crude oil (viscosity of 84.2 mPa s at 30 °C and shear rate of 7.336 s-1) were mixed according to the water-to-oil volume ratio of 1:9, 2 :8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1 to prepare a total volume of 20mL, mix and seal; then stir in a water bath at 30°C for 30 minutes, Observe the emulsification situation. After stirring, use a viscometer to test the apparent viscosity of the emulsion at 30°C and a shear rate of 7.336s-1, see Table 2. It can be observed that the viscosity of the high internal phase emulsion formed by the nano-solid particle emulsifiers in Examples 1 to 3 is higher than that of the emulsion of crude oil and water, and when the water content is more than 70%, in Comparative Example 1, the silane coupling agent grafted The viscosity of the emulsion formed by the long-chain nano-silica is lower than the viscosity of the emulsion formed in Examples 1-3. And the viscosity of the emulsion formed in Example 4 is less than that of the nano-solid particle emulsifier of the present invention.

Table 2 Viscosities of emulsions formed by water, nanoemulsifier dispersions and crude oil under different water-to-oil ratio conditions

4. Microscopic morphology of high inward water-in-oil emulsion with water content of 80%

The nanoemulsifier is adsorbed on the oil-water interface under shear induction. Due to the hydrophobicity of the nanoemulsifier, the oil-water interface is reversely bent to form a water-in-oil emulsion. The viscosity of the emulsion is higher than that of crude oil. Under the condition of 80%, the emulsion has no phase change, and the viscosity of the emulsion is directly proportional to the water content and inversely proportional to the oil content, which reflects the self-adaptive control of the mobility, stable displacement front and intelligent displacement of the emulsion in the reservoir conditions. feature. The microscopic appearance of the emulsion with a water content of 80% (nano solid particle emulsifier 1 dispersion and crude oil volume ratio 8:2) is shown in Figure 2, which proves that the water-in-oil emulsion at a very high water content condition can still Forms water-in-oil emulsions.

The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that these embodiments are only for describing the present invention, and should not be construed as limiting the scope of the present invention. On the premise of not departing from the principle of the present invention, further improvements can be made, and these improvements should also be regarded as the protection of the present invention.

Claims (6)

1. a preparation method of nano titanium dioxide solid particle emulsifier, is characterized in that, comprises the following steps: (1) Add hydrophilic nano-titanium dioxide into absolute ethanol and disperse it to obtain a dispersion; (2) adding a phthalate coupling agent to the dispersion liquid and causing a coupling reaction with titanium dioxide, in terms of mass percentage, the phthalate coupling agent is 8-15% of the mass of the nano-titanium dioxide; (3) Add long-chain brominated alkanes dropwise to the reaction liquid obtained in step (2), keep stirring during the dropwise addition, and react for 10~12h at 60~70°C with continuous stirring after the dropwise addition; In terms of parts, the addition of the long-chain brominated alkane is 1 to 2 times the addition of the nano-titanium dioxide, and after the reaction is completed, it is separated and purified to obtain final product; The titanate coupling agent is isopropyl tris (dioctyl pyrophosphate acyloxy) titanate, bis (dioctyl pyrophosphate acyloxy) ethylene titanate, isopropoxy diolate one or more of acid acyloxy (dioctyl phosphate acyloxy) titanate; at least one. 2. The method according to claim 1, characterized in that: in step (1), the titanium dioxide is hydrophilic titanium dioxide with a diameter of 20-100 nm, and the addition amount of the titanium dioxide is the 0.02 to 0.05 times that of water ethanol. 3. The method according to claim 1, characterized in that in step (1), the preparation time of the dispersion liquid is 20-40 minutes. 4 . The method according to claim 1 , characterized in that, in step (2), the reaction temperature is 60-70° C., and the reaction time is 10-12 hours. 5. The method according to claim 1, characterized in that: the specific operation of said separation and purification is: the product after the reaction is filtered, while using absolute ethanol to wash several times, after the separation is completed, the filter cake is subjected to vacuum After drying, after drying, it is crushed. 6. A nano-titanium dioxide solid particle emulsifier, which is prepared by the method according to any one of claims 1 to 5.

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