Preparation method and performance test of temperature-responsive emulsifier for improving heavy oil recovery

Abstract

The application provides a preparation method and performance test of a temperature-responsive emulsifier for improving heavy oil recovery. The emulsifier is a silicon-based material, has a sheet-shaped Janus structure, can be stably adsorbed on the surface of heavy oil droplets and effectively reduce the interfacial tension between heavy oil and water, and therefore has excellent stable emulsion performance. In addition, the emulsifier has temperature response capability, can realize high-temperature emulsification and low-temperature demulsification, and has strong reference value and application prospect in the actual scene of reservoir development.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field chemical agents, and in particular to a method for preparing and testing a temperature-responsive emulsifier for improving heavy oil recovery. Background Technology

[0002] Petroleum is a crucial component of the global energy system, and the enormous energy demand in recent years has led to the continuous depletion of easily exploitable petroleum (light petroleum) resources. Against this backdrop, heavy oil resources have shown immense application potential, and their development and production have received increasing attention. Due to the low fluidity and high viscosity of heavy oil, its extraction is significantly more difficult than that of conventional crude oil. Pickering emulsification viscosity reduction is a highly efficient heavy oil extraction technology. It involves emulsifying heavy oil and water into an oil-in-water emulsion using nanoparticles, thereby significantly reducing the viscosity of heavy oil and increasing recovery rates. However, stable emulsions are difficult to demulsify quickly once they reach the surface, and subsequent complex processing increases costs and introduces various environmental problems.

[0003] To address the aforementioned issues, stimulus-responsive emulsifiers have emerged. These are intelligent emulsifiers whose physicochemical properties or structure change in response to changes in external environmental conditions, thereby causing an emulsification-demulsification transition in the emulsion. Currently, research has been conducted on response conditions including pH, magnetism, temperature, redox reactions, CO2, and light. Among these, temperature-responsive emulsifiers are gaining increasing popularity due to their ease of operation, high sensitivity, and environmental friendliness. However, current research on temperature-responsive emulsifiers focuses on low-temperature emulsification and high-temperature demulsification, which does not align with the actual reservoir environment. Therefore, developing temperature-responsive emulsifiers suitable for the high-temperature environment of oil reservoirs is of great significance in improving heavy oil recovery. Summary of the Invention

[0004] One aspect of the present invention provides a method for preparing an emulsifier with temperature-responsive properties, which specifically includes the following steps:

[0005] 1) Toluene, 3-aminopropyltriethylsilane, tetraethyl orthosilicate, and Span-80 were mixed as the oil phase, and then an acidic aqueous solution containing Tween-80 was added. The mixture was stirred at high speed, reacted, ultrasonically pulverized, centrifuged, and dried to obtain product 1.

[0006] 2) Add product 1 to a mixed solution of toluene and triethylamine, add 2-bromoisobutyryl bromide under ice bath conditions, then transfer to room temperature for reaction, and centrifuge and dry to obtain product 2;

[0007] 3) Add product 2 to a mixture containing cuprous bromide, 2,2 ，The emulsifier is obtained by mixing bipyridine, azobisisobutyronitrile, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide and anhydrous acetonitrile with stirring, reacting, centrifuging, and drying.

[0008] In one specific embodiment, in step 1), the pH of the aqueous solution is adjusted to 2.5 using 2 mol / L hydrochloric acid.

[0009] In one specific embodiment, in step 1), the high-speed stirring speed is 14000 rpm / min.

[0010] In one specific embodiment, in step 1), the high-speed stirring time is 2.5 min.

[0011] In one specific embodiment, in step 1), the reaction temperature is 70°C.

[0012] In one specific implementation, in step 1), the reaction time is 12 hours.

[0013] In one specific embodiment, in step 1), the ultrasonic pulverization time is 30 min.

[0014] In one specific embodiment, in step 2), the ice bath reaction time is 30 min.

[0015] In one specific implementation, in step 2), the reaction time at room temperature is 24 hours.

[0016] In one specific embodiment, in step 3), product 2, cuprous bromide, and 2,2 ， The molar ratio of 1-bipyridine, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, azobisisobutyronitrile, and anhydrous acetonitrile is 225:1.5:3:118:1:10845.

[0017] In one specific embodiment, in step 3), the reaction temperature is 75°C.

[0018] In one specific implementation, in step 3), the reaction time is 24 hours.

[0019] The beneficial effects of this invention are:

[0020] The emulsifier prepared by this invention can stabilize at the heavy oil-water interface and reduce interfacial tension under certain conditions to achieve emulsification of heavy oil. At the same time, it can stabilize the emulsion under high temperature conditions and separate oil and water under low temperature conditions, making it suitable for application scenarios in oil fields. Attached Figure Description

[0021] Figure 1The infrared spectrum of the emulsifier is shown.

[0022] Figure 2 The image shows scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the emulsifier.

[0023] Figure 3 The test curves showing the effect of emulsifiers on reducing interfacial tension are displayed.

[0024] Figure 4 The image shows a cryo-scanning electron microscope image of emulsifier adsorbed on the surface of heavy oil droplets.

[0025] Figure 5 Metallographic micrographs of heavy oil-deionized water emulsions formed by emulsifiers at different addition amounts are shown. Detailed Implementation

[0026] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0027] Example 1

[0028] Synthesis method of temperature-responsive silicone-based Janus emulsifier:

[0029] (1) Weigh 0.5 g of Tween-80 and dissolve it in 30 mL of deionized water, then adjust the pH to 2.5 with 2 mol / L HCl to form the aqueous phase. Weigh 60 g of toluene, 5.2 g of tetraethyl orthosilicate, 1.1 g of 3-aminopropyltriethylsilane, and 4.5 g of Span-80 to prepare a mixed solution. Then add the aqueous phase to the mixed solution and homogenize at 14000 rpm for 2.5 min to form an oil-in-water emulsion. Stir the reaction at 70 °C for 12 h. Then, centrifuge to purify the product and disperse it in anhydrous ethanol, followed by ultrasonic pulverization for 2 h. Finally, obtain product 1 by centrifugation and freeze-drying.

[0030] (2) Disperse 0.05 g of product 1 in 20 mL of toluene containing 0.4 mL of triethylamine, then add 0.5 mL of 2-bromoisobutyryl bromide dropwise under ice bath conditions and stir for 30 min. Then transfer the reaction to room temperature and continue for 24 h. Finally, obtain product 2 by centrifugation and freeze drying.

[0031] (3) Weigh 5.5g of product 2, 0.13g of cuprous bromide, and 2,2 ，0.19 g of bipyridine and 6.6 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) were dispersed in 75 mL of anhydrous acetonitrile, and the mixture was stirred at 75 °C for 30 min. Subsequently, 0.0975 g of azobisisobutyronitrile (AIBN) dispersed in 15 mL of anhydrous acetonitrile was added to the aforementioned solution, and the mixture was stirred at 75 °C for 24 h. Finally, the final emulsifier product was obtained by centrifugation and freeze-drying.

[0032] Characterization:

[0033] Product 1, Product 2, and the emulsifier were characterized by Fourier transform infrared (FTIR) detection. Using the KBr pellet method, Product 1, Product 2, and the emulsifier samples were vacuum dried until constant mass. Approximately 200 mg of dried KBr powder and approximately 2 mg of the sample powder were weighed and ground in an agate mortar to prepare powder samples with an average particle size of approximately 2 μm. These samples were then compressed into tablets (approximately 12 MPa) to obtain transparent, sheet-like samples for detection. Detection conditions: wavelength range 500-4000 cm⁻¹. -1 Resolution is 2cm -1 The results are shown below. Figure 1 .

[0034] from Figure 1 As can be seen, 469.23cm -1 and 802.34cm -1 The peak value is the Si-O tensile vibration peak at 1106.15 cm⁻¹. -1 The peak at 2923.09 cm⁻¹ represents the antisymmetric tensile vibration of Si-O-Si. -1 and 2855.12cm -1 The presence of both asymmetric and symmetric stretching vibration peaks of -CH2 at 1536.88 cm⁻¹ indicates the successful preparation of product 1. -1 The peak at 1644.51 cm⁻¹ represents the stretching vibration of the -C=O group in the amide group. -1 The peak at 608.13 cm⁻¹ represents the bending vibration of -CH₃, indicating the successful preparation of product 2. -1 The presence of the CS tensile vibration peak at this location indicates the successful preparation of the emulsifier.

[0035] The morphology of the emulsifier was imaged using scanning electron microscopy and transmission electron microscopy. The results are shown below. Figure 2 .

[0036] from Figure 2 As can be seen, the final emulsifier product has a two-dimensional sheet-like structure and a rough morphology on one side of the surface, indicating the successful grafting of the surface group SBMA.

[0037] Example 2

[0038] Interfacial performance testing of temperature-responsive silicone-based Janus emulsifiers:

[0039] 1. Test to reduce interfacial tension

[0040] The interfacial tension (IFT) between nanofluids formed by dispersing emulsifiers of different mass fractions (0 wt%, 0.005 wt%, 0.025 wt%, and 0.1 wt%) in deionized water and heavy oil was measured using an interfacial tensiometer. The results are shown in [Figure number missing]. Figure 3 .

[0041] from Figure 3 As can be seen, the IFT between deionized water and heavy oil is 34.26 mN / m when no emulsifier is added. When an emulsifier is added, the IFT is significantly reduced, and the degree of reduction increases with the increase of the mass fraction of emulsifier. 0.1 wt% emulsifier can reduce the IFT by 11.02 mN / m.

[0042] 2. Emulsifier interfacial state test

[0043] Cryo-scanning electron microscopy was used to test the interfacial state of the emulsifier (added at a mass fraction of 0.75 wt%) in the formed heavy oil-deionized water Pickering emulsion system (specific preparation method is shown in Example 3). Results are shown below. Figure 4 .

[0044] from Figure 4 As can be seen, the emulsifier is stably adsorbed on the surface of heavy oil droplets, which can reduce the aggregation rate of heavy oil droplets, that is, it is stable at the oil-water interface and has stable interfacial activity.

[0045] Example 3

[0046] Emulsion performance testing of temperature-responsive silicone-based Janus emulsifier:

[0047] 1. Emulsion preparation and water separation rate calculation

[0048] 0.0225 g, 0.045 g, 0.0675 g and 0.09 g of emulsifier were weighed and dispersed in 9 mL of deionized water (i.e., the mass fractions of emulsifier added were 0.25 wt%, 0.5 wt%, 0.75 wt% and 1 wt%, respectively). Then, 1 mL of heavy oil (the heavy oil was selected from Chunliang Oil Production Plant of Shengli Oilfield, China, and the relevant parameters are shown in Table 1) was added. The mixture was emulsified for 5 min at 65℃ and 4500 rpm using an ultrasonic cell disruptor to obtain Pickering emulsion.

[0049] Table 1

[0050]

[0051] 2. Microscopic imaging of emulsions

[0052] Approximately 1.5 mL of the prepared Pickering emulsion was placed on a glass slide, and the microstructure of the heavy oil-water Pickering emulsion particles was observed using a metallographic microscope. The results are shown below. Figure 5 .

[0053] from Figure 5 As can be seen, compared with the system without emulsifier, the addition of different mass fractions of emulsifier can form Pickering emulsions in different states. Emulsion particles can be clearly observed, and the average size of the emulsion particle diameter decreases as the mass fraction of emulsifier increases (from 0.25 wt% to 1 wt%) (from 72 μm to 35 μm).

[0054] 3. Calculation of emulsion water separation rate

[0055] The resulting emulsion was poured into a 15 mL graduated cylinder and allowed to stand at 65 °C. The volume of the aqueous phase precipitated was recorded at different times (0.25 h, 0.5 h, 0.75 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 12 h, and 24 h). The water separation ratio (SR) of the emulsion was calculated using formula (1).

[0056]

[0057] Among them, V sw V represents the volume of the aqueous phase precipitated from the emulsion. w This indicates the initial volume of deionized water added.

[0058] The smaller the SR value of an emulsion, the less water is separated, and the more stable the emulsion tends to be.

[0059] The results of the emulsion stability (water separation rate) test are shown in Table 2.

[0060] As can be seen from Table 2, the water separation rate of the emulsion increases with the extension of the standing time and decreases with the increase of the emulsifier concentration.

[0061] Table 2

[0062]

[0063] Example 4

[0064] Temperature response performance test of temperature-responsive silicone-based Janus emulsifier:

[0065] 0.0675 g of emulsifier was weighed and dispersed in 9 mL of deionized water (i.e., the mass fraction of emulsifier added was 0.75 wt%). Then, 1 mL of heavy oil was added, and the mixture was emulsified for 5 min at 65 °C and 4500 rpm using an ultrasonic cell disruptor to obtain Pickering emulsion. The emulsion was placed in constant temperature environments of 25 °C, 35 °C, 45 °C, 55 °C and 65 °C, and the state was observed and the water separation rate was recorded.

[0066] The water separation rate of the emulsion after standing for 12 hours is shown in Table 3.

[0067] As can be seen from Table 3, the water separation rate of the emulsion decreases with increasing ambient temperature, indicating that the stability of the emulsion improves.

[0068] Table 3

[0069]

Claims

1. A method for preparing a temperature-responsive emulsifier suitable for actual reservoir temperature conditions, comprising the following steps: 1) Weigh 0.5 g of Tween-80 and dissolve it in 30 mL of deionized water, and adjust the pH to 2.5 with 2 mol / L HCl to form the aqueous phase; weigh 60 g of toluene, 5.2 g of tetraethyl orthosilicate, 1.1 g of 3-aminopropyltriethylsilane, and 4.5 g of Span-80 to prepare a mixed solution; then add the aqueous phase to the mixed solution, homogenize at 14000 rpm for 2.5 min to form an oil-in-water emulsion, and stir the reaction at 70 ℃ for 12 h; then, centrifuge to purify the product and disperse it in anhydrous ethanol, and sonicate it for 2 h; finally, obtain product 1 by centrifugation and freeze drying. 2) Disperse 0.05 g of product 1 in 20 mL of toluene containing 0.4 mL of triethylamine, then add 0.5 mL of 2-bromoisobutyryl bromide dropwise under ice bath conditions and stir for 30 min. Then transfer the reaction to room temperature and continue for 24 h. Finally, obtain product 2 by centrifugation and freeze drying. 3) Weigh 5.5 g of product 2, 0.13 g of cuprous bromide, 0.19 g of 2,2'-bipyridine, and 6.6 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and disperse them in 75 mL of anhydrous acetonitrile. Then, stir the mixture at 75 °C for 30 min. Subsequently, disperse 0.0975 g of azobisisobutyronitrile in 15 mL of anhydrous acetonitrile and add it to the aforementioned solution. Continue stirring the mixture at 75 °C for 24 h. Finally, obtain the emulsifier by centrifugation and freeze-drying. This emulsifier can achieve emulsification of heavy oil at high temperatures and oil-water separation at low temperatures.

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