Thickening agent, oil displacement agent, preparation method and application thereof

Abstract

This invention discloses a thickener, an oil displacement agent, and their preparation method and application, belonging to the field of petroleum extraction technology. The molecular formula of the thickener is: [formula omitted for brevity]. Wherein, m takes values ​​from 5000 to 50000, n takes values ​​from 2000 to 50000, and p takes values ​​from 2000 to 50000. This thickener can increase the viscosity of carbon dioxide, improve the thickening effect of carbon dioxide, and thus improve the efficiency of carbon dioxide oil displacement. For example, under conditions of 60℃ and 15MPa, a concentration of 0.5wt% can achieve a carbon dioxide thickening effect of over 15 mPa·s.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, and more specifically, to a thickener, an oil displacement agent, and their preparation methods and applications. Background Technology

[0002] With the increasingly severe impact of the greenhouse effect, carbon dioxide flooding technology has attracted widespread attention worldwide due to its advantages of simultaneously improving oil recovery and reducing emissions. Carbon dioxide flooding is an effective tertiary oil recovery technology. Its principle is that when carbon dioxide dissolves in large quantities in crude oil, it causes the crude oil to expand in volume, decrease in viscosity, and reduce the interfacial tension between oil and water, thereby improving oil displacement efficiency.

[0003] However, the biggest drawback of carbon dioxide is its low viscosity under formation conditions. Compared to crude oil, the mobility ratio is too large, making it prone to viscous fingering and channeling, resulting in an unfavorable mobility ratio. Carbon dioxide channeling in the reservoir severely impacts the degree to which gas-driven oil recovery is enhanced. Wells with severe gas channeling, while showing significant oil production increases, experience a sharp decline in fluid production, or even cease production altogether. Furthermore, due to gravity over-covering, gas can channel to the upper reservoir during carbon dioxide displacement, forming channeling channels. This results in a smaller swept volume for gas-driven operations, severely affecting the oil displacement effect of carbon dioxide flooding and increasing the difficulty of sealing off channeled gas.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a thickener, an oil displacement agent, and their preparation method and application, so as to solve or improve the above-mentioned technical problems.

[0006] This invention can be implemented as follows:

[0007] In a first aspect, the present invention provides a thickener having the following molecular formula: Where m ranges from 5000 to 50000, n ranges from 2000 to 50000, and p ranges from 2000 to 50000.

[0008] In a second aspect, the present invention provides a method for preparing a thickener as described in the foregoing embodiments, comprising the following steps: 2-trimethylsiloxy-4-propenoxybenzophenone, 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid and xylene are reacted at 70°C to 80°C for 1 to 2 hours in the presence of an initiator, and then the temperature is raised to 90°C to 95°C and the reaction is maintained for 1 to 2 hours to obtain a mixture;

[0009] Mix the mixture with hydroquinone for 15-30 minutes to terminate the reaction; distill under reduced pressure until 1 / 4-1 / 3 of the xylene remains, then stop distillation; cool to precipitate the solid to obtain the thickener.

[0010] In an optional embodiment, the molar ratio of 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid, and 2-trimethylsiloxy-4-propenoxybenzophenone is (0.5-1):(0.5-1):1; the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is (20-30):1; and the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is (0.01-0.02):1.

[0011] In an optional embodiment, the weight ratio of the initiator to 2-trimethylsiloxy-4-propenoxybenzophenone is (0.03 to 0.06):1.

[0012] In an optional embodiment, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

[0013] In an optional embodiment, cooling to precipitate solids includes: first cooling to room temperature, and then adding an additive to precipitate solids.

[0014] In an optional embodiment, the weight ratio of the auxiliary agent to 2-trimethylsiloxy-4-propenoxybenzophenone is (30-40):1.

[0015] In an optional implementation, the adjuvant includes ethanol.

[0016] Thirdly, the present invention provides an oil displacement agent comprising a solubilizer and a thickener as described in the foregoing embodiments.

[0017] In an optional embodiment, the mass ratio of solubilizer to thickener is 2:1 to 3:1.

[0018] In an optional embodiment, the solubilizer includes at least one selected from propyl acetate, butyl acetate, hexyl acetate, propyl propionate, butyl propionate, and butyl butyrate.

[0019] In an optional embodiment, the viscosity-average molecular weight of the oil displacement agent is 5,000,000 to 1,000,000.

[0020] Fourthly, the present invention provides a method for preparing an oil displacement agent as described in any of the foregoing embodiments, comprising the following steps: mixing a thickener and a solubilizer, allowing the mixture to stand, and obtaining the oil displacement agent.

[0021] In an optional implementation, the settling time is 12h to 24h.

[0022] Fifthly, the present invention provides the application of the oil displacement agent as described in any of the foregoing embodiments in improving CO2 flooding recovery.

[0023] The beneficial effects of this invention include:

[0024] The thickener in the oil displacement agent of this invention is a polymer based on monomers of 2-trimethylsiloxy-4-propenoxybenzophenone, 3-methylcinnamic acid, and 2-(trifluoromethyl)acrylic acid. Specifically, 2-trimethylsiloxy-4-propenoxybenzophenone can significantly increase CO2 viscosity; 3-methylcinnamic acid and 2-(trifluoromethyl)acrylic acid contain carboxyl groups, which can intertwine to increase the viscosity of both the thickener and CO2; 2-(trifluoromethyl)acrylic acid can also increase CO2 solubility. This thickener can increase the viscosity of carbon dioxide, improve the thickening effect of carbon dioxide, and thus improve the efficiency of carbon dioxide oil displacement.

[0025] The oil displacement agent obtained by combining the above thickener with solubilizer can increase the viscosity of carbon dioxide, reduce its mobility ratio with crude oil, reduce carbon dioxide leakage in the reservoir, and improve the efficiency of carbon dioxide flooding under low dosage conditions. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0027] The following provides a detailed description of the thickener, oil displacement agent, preparation method, and application provided by this invention.

[0028] This invention provides a thickener with the following molecular formula: Where m ranges from 5000 to 50000, n ranges from 2000 to 50000, and p ranges from 2000 to 50000.

[0029] In some implementations, the value of m can be 5000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000 or 50000, or other values ​​in the range of 5000 to 50000.

[0030] In some implementations, the value of n can be 2000, 5000, 8000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000 or 50000, or other values ​​in the range of 2000 to 50000.

[0031] In some implementations, the value of p can be 2000, 5000, 8000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000 or 50000, or other values ​​in the range of 2000 to 50000.

[0032] The aforementioned thickener is a polymer based on monomers of 2-trimethylsiloxy-4-propenoxybenzophenone, 3-methylcinnamic acid, and 2-(trifluoromethyl)acrylic acid. Specifically, 2-trimethylsiloxy-4-propenoxybenzophenone can significantly increase CO2 viscosity; 3-methylcinnamic acid and 2-(trifluoromethyl)acrylic acid contain carboxyl groups, which can intertwine and increase both the thickener and CO2 viscosity; 2-(trifluoromethyl)acrylic acid can also increase CO2 solubility.

[0033] At 60°C and 15 MPa, a concentration of 0.5 wt% of this thickener can achieve a carbon dioxide thickening effect of 17.6 mPa·s.

[0034] Accordingly, the present invention also provides a method for preparing the above-mentioned thickener, which includes the following steps: 2-trimethylsiloxy-4-propenoxybenzophenone, 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid and xylene are reacted at 70℃~80℃ for 1h~2h in the presence of an initiator, and then the temperature is raised to 90℃~95℃ and the reaction is maintained for 1h~2h to obtain a mixture;

[0035] Mix the mixture with hydroquinone for 15-30 minutes to terminate the reaction; distill under reduced pressure until 1 / 4-1 / 3 of the xylene remains, then stop distillation; cool to precipitate the solid to obtain the thickener.

[0036] The reaction equations involved in the preparation of this thickener include:

[0037]

[0038] In some alternative embodiments, the molar ratio of 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid, and 2-trimethylsiloxy-4-propenoxybenzophenone can be (0.5-1):(0.5-1):1, such as 0.5:0.5:1, 0.5:0.6:1, 0.6:0.6:1, 0.7:0.8:1, 0.75:0.5:1, 0.75:0.75:1, 0.8:0.9:1, 0.9:0.75:1, 1:0.75:1, or 1:1:1, or other values ​​within the range of (0.5-1):(0.5-1):1.

[0039] The weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone can be (20-30):1, such as 20:1, 22:1, 25:1, 28:1 or 30:1, or other values ​​within the range of (20-30):1.

[0040] Xylene is a solvent required for polymer polymerization. If too little xylene is used, it will cause explosive polymerization and affect product quality; if too much xylene is used, it will reduce production efficiency.

[0041] The weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone can be (0.01 to 0.02):1, such as 0.01:1, 0.015:1 or 0.02:1, or other values ​​within the range of (0.01 to 0.02):1.

[0042] Hydroquinone is used as a terminator for the polymerization chain reaction. If too little hydroquinone is used, it will not be conducive to terminating the polymerization chain reaction; if too much hydroquinone is used, it will easily lead to waste.

[0043] The weight ratio of the initiator to 2-trimethylsiloxy-4-propenoxybenzophenone can be (0.03 to 0.06):1, such as 0.03:1, 0.04:1, 0.05:1 or 0.06:1, or other values ​​within the range of (0.03 to 0.06):1.

[0044] The initiator may, by way of example but not by way of limitation, include at least one of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide.

[0045] In some alternative embodiments, cooling to precipitate solids includes: first cooling to room temperature, then adding an additive to precipitate the solids. The additives are primarily used to induce solid precipitation.

[0046] The weight ratio of the auxiliary agent to 2-trimethylsiloxy-4-propenoxybenzophenone can be (30-40):1, such as 30:1, 32:1, 35:1, 38:1 or 40:1, or other values ​​within the range of (30-40):1.

[0047] Exemplary but not limited additives may include ethanol.

[0048] In addition, the present invention provides an oil displacement agent comprising a solubilizer and the aforementioned thickener.

[0049] In some alternative embodiments, the mass ratio of solubilizer to thickener can be 2:1 to 3:1, such as 2:1, 2.5:1 or 3:1, or other values ​​within the range of 2:1 to 3:1.

[0050] The solubilizer may, by way of example but not by way of limitation, include at least one of propyl acetate, butyl acetate, hexyl acetate, propyl propionate, butyl propionate and butyl butyrate.

[0051] The use of the aforementioned solubilizers can significantly improve the solubility of CO2 in thickeners. However, excessive use of solubilizers can lead to a decrease in product viscosity and a reduction in oil displacement effect.

[0052] In some alternative embodiments, the viscosity-average molecular weight of the above-mentioned oil displacement agent can be 5,000,000 to 1,000,000.

[0053] Accordingly, the present invention also provides a method for preparing the above-mentioned oil displacement agent, which includes the following steps: mixing a thickener and a solubilizer, allowing the mixture to stand, and obtaining the oil displacement agent.

[0054] In some alternative implementations, the settling time can be 12h to 24h, such as 12h, 14h, 16h, 18h, 20h, 22h or 24h, or other values ​​within the range of 12h to 24h.

[0055] Furthermore, the present invention also provides an application of the above-mentioned oil displacement agent in improving CO2 flooding recovery.

[0056] The aforementioned oil displacement agent can increase the viscosity of carbon dioxide and reduce its mobility ratio with crude oil under low dosage conditions, thereby reducing carbon dioxide leakage in the reservoir and improving the efficiency of carbon dioxide oil displacement.

[0057] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0058] Example 1

[0059] This embodiment provides an oil displacement agent, which is prepared by the following method:

[0060] (1) Add 0.02 mol of 2-trimethylsiloxy-4-propenoxybenzophenone, 0.01 mol of 3-methylcinnamic acid, 0.012 mol of 2-(trifluoromethyl)acrylic acid and 130.6 g of xylene (the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is about 19.9:1) to the reactor in sequence. Purge the reactor and pipeline with nitrogen for 5 min to replace the air. Stir to dissolve. Add 0.2 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.03:1). Slowly raise the temperature to 70°C and keep it at that temperature for 1 h. Continue to raise the temperature to 90°C and keep it at that temperature for 1 h to obtain a viscous mixture.

[0061] (2) Add 0.07 g hydroquinone (the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.01:1) to the mixture, continue stirring for 15 min, and terminate the reaction; distill the mixture under reduced pressure, and stop distillation when 1 / 3 of the xylene remains; cool to room temperature, add 195.9 g ethanol (the weight ratio of ethanol to 2-trimethylsiloxy-4-propenoxybenzophenone is about 30:1), precipitate solid, filter, dry, and obtain thickener.

[0062] (3) Mix 5g of thickener and 15g of propyl acetate and let stand for 24 hours to obtain the product oil displacement agent.

[0063] Example 2

[0064] This embodiment provides an oil displacement agent, which is prepared by the following method:

[0065] (1) Add 0.02 mol of 2-trimethylsiloxy-4-propenoxybenzophenone, 0.012 mol of 3-methylcinnamic acid, 0.012 mol of 2-(trifluoromethyl)acrylic acid and 145 g of xylene (the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is about 22.2:1) to the reactor in sequence. Purge the reactor and pipeline with nitrogen for 6 min to replace the air. Stir to dissolve. Add 0.24 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.036:1). Slowly raise the temperature to 80°C and keep it at that temperature for 2 h. Continue to raise the temperature to 92°C and keep it at that temperature for 1 h to obtain a viscous mixture.

[0066] (2) Add 0.08 g hydroquinone (the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.012:1) to the mixture, continue stirring for 25 min, terminate the reaction, distill the mixture under reduced pressure, stop distillation when 1 / 3 of xylene remains, cool to room temperature, add 214 g ethanol (the weight ratio of ethanol to 2-trimethylsiloxy-4-propenoxybenzophenone is about 32.8:1), precipitate solid, filter, dry, and obtain thickener.

[0067] (3) Mix 5g of thickener and 14g of butyl acetate and let stand for 12h to obtain the product oil displacement agent.

[0068] Example 3

[0069] This embodiment provides an oil displacement agent, which is prepared by the following method:

[0070] (1) Add 0.02 mol of 2-trimethylsiloxy-4-propenoxybenzophenone, 0.014 mol of 3-methylcinnamic acid, 0.016 mol of 2-(trifluoromethyl)acrylic acid, and 155 g of xylene (the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is approximately 23.7:1) to the reactor in sequence. Purge the reactor and pipeline with nitrogen for 8 min to replace the air. Stir to dissolve. Add 0.28 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsiloxy-4-propenoxybenzophenone is approximately 0.04:1). Slowly raise the temperature to 75°C and keep the reaction temperature for 1 h. Continue to raise the temperature to 93°C and keep the reaction temperature for 2 h to obtain a viscous mixture.

[0071] (2) Add 0.09 g hydroquinone (the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.013:1) to the mixture, continue stirring for 20 min, terminate the reaction, distill the mixture under reduced pressure, stop distillation when 1 / 4 of the xylene remains, cool to room temperature, add 226 g ethanol (the weight ratio of ethanol to 2-trimethylsiloxy-4-propenoxybenzophenone is about 34.6:1), precipitate solid, filter, dry, and obtain thickener.

[0072] (3) Mix 5g of thickener and 12.6g of hexyl acetate and let stand for 20h to obtain the product oil displacement agent.

[0073] Example 4

[0074] This embodiment provides an oil displacement agent, which is prepared by the following method:

[0075] (1) Add 0.02 mol of 2-trimethylsiloxy-4-propenoxybenzophenone, 0.015 mol of 3-methylcinnamic acid, 0.01 mol of 2-(trifluoromethyl)acrylic acid and 160 g of xylene (the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is about 24.5:1) to the reactor in sequence. Purge the reactor and pipeline with nitrogen for 10 min to replace the air. Stir to dissolve. Add 0.3 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.046:1). Slowly raise the temperature to 72°C and keep it at that temperature for 2 h. Continue to raise the temperature to 94°C and keep it at that temperature for 1.5 h to obtain a viscous mixture.

[0076] (2) Add 0.1g hydroquinone (the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.015:1) to the mixture, continue stirring for 30min, terminate the reaction, distill the mixture under reduced pressure, stop distillation when 1 / 4 of the xylene remains, cool to room temperature, add 238g ethanol (the weight ratio of ethanol to 2-trimethylsiloxy-4-propenoxybenzophenone is about 36.45:1), precipitate solid, filter, dry, and obtain thickener.

[0077] (3) Mix 5g of thickener and 13.6g of propyl propionate and let stand for 18h to obtain the product oil displacement agent.

[0078] Example 5

[0079] This embodiment provides an oil displacement agent, which is prepared by the following method:

[0080] (1) Add 0.02 mol of 2-trimethylsiloxy-4-propenoxybenzophenone, 0.016 mol of 3-methylcinnamic acid, 0.018 mol of 2-(trifluoromethyl)acrylic acid and 176 g of xylene (the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is about 26.9:1) to the reactor in sequence. Purge the reactor and pipeline with nitrogen for 8 min to replace the air. Stir to dissolve. Add 0.36 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.055:1). Slowly raise the temperature to 76 °C and keep the reaction at this temperature for 1.5 h. Continue to raise the temperature to 91 °C and keep the reaction at this temperature for 1.6 h to obtain a viscous mixture.

[0081] (2) Add 0.12g hydroquinone (the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.018:1) to the mixture, continue stirring for 20min, terminate the reaction, distill the mixture under reduced pressure, stop distillation when 1 / 3 of xylene remains, cool to room temperature, add 256g ethanol (the weight ratio of ethanol to 2-trimethylsiloxy-4-propenoxybenzophenone is about 39.2:1), precipitate solid, filter, dry, and obtain thickener.

[0082] (3) Mix 5g of thickener and 11.8g of butyl propionate and let stand for 16h to obtain the product oil displacement agent.

[0083] Example 6

[0084] This embodiment provides an oil displacement agent, which is prepared by the following method:

[0085] (1) Add 0.02 mol of 2-trimethylsiloxy-4-propenoxybenzophenone, 0.018 mol of 3-methylcinnamic acid, 0.015 mol of 2-(trifluoromethyl)acrylic acid and 184 g of xylene (the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is about 28.2:1) to the reactor in sequence. Purge the reactor and pipeline with nitrogen for 10 min to replace the air. Stir to dissolve. Add 0.32 g of benzoyl peroxide (the weight ratio of benzoyl peroxide to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.049:1). Slowly raise the temperature to 77°C and keep the reaction at this temperature for 1.2 h. Continue to raise the temperature to 94°C and keep the reaction at this temperature for 1.2 h to obtain a viscous mixture.

[0086] (2) Add 0.12 g hydroquinone (the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.018:1) to the mixture, continue stirring for 25 min, terminate the reaction, distill the mixture under reduced pressure, stop distillation when 1 / 3 of xylene remains, cool to room temperature, add 247 g ethanol (the weight ratio of ethanol to 2-trimethylsiloxy-4-propenoxybenzophenone is about 37.8:1), precipitate solid, filter, dry, and obtain thickener.

[0087] (3) Mix 5g of thickener and 10.9g of butyl butyrate and let stand for 21h to obtain the product oil displacement agent.

[0088] Example 7

[0089] This embodiment provides an oil displacement agent, which is prepared by the following method:

[0090] (1) Add 0.02 mol of 2-trimethylsiloxy-4-propenoxybenzophenone, 0.02 mol of 3-methylcinnamic acid, 0.015 mol of 2-(trifluoromethyl)acrylic acid and 195.6 g of xylene (the weight ratio of xylene to 2-trimethylsiloxy-4-propenoxybenzophenone is approximately 29.9:1) to the reactor in sequence. Purge the reactor and pipeline with nitrogen for 7 min to replace the air. Stir to dissolve. Add 0.39 g of azobenzoyl peroxide (the weight ratio of azobenzoyl peroxide to 2-trimethylsiloxy-4-propenoxybenzophenone is approximately 0.06:1). Slowly raise the temperature to 75 °C and keep the reaction temperature for 1.8 h. Continue to raise the temperature to 95 °C and keep the reaction temperature for 1.3 h to obtain a viscous mixture.

[0091] (2) Add 0.13g hydroquinone (the weight ratio of hydroquinone to 2-trimethylsiloxy-4-propenoxybenzophenone is about 0.02:1) to the mixture, continue stirring for 30min, terminate the reaction, distill the mixture under reduced pressure, stop distillation when 1 / 4 of the xylene remains, cool to room temperature, add 260.8g ethanol (the weight ratio of ethanol to 2-trimethylsiloxy-4-propenoxybenzophenone is about 39.9:1), precipitate solid, filter, dry, and obtain thickener.

[0092] (3) Mix 5g of thickener and 10g of propyl acetate and let stand for 24 hours to obtain the oil displacement agent product.

[0093] The oil displacement agents prepared in Examples 1-7 of this invention were dissolved in carbon dioxide to a concentration of 0.5 wt%, placed in a pressure-resistant, temperature-controlled closed Hacker rheometer, stirred until homogeneous, and the shear rate was adjusted to 170 s. -1 The system was subjected to stepwise heating at a pressure of 15 MPa to test the viscosity of supercritical carbon dioxide (scCO2) at 60℃, 75℃, and 90℃, with carbon dioxide used as a blank control. The test results are shown in Table 1.

[0094] Table 1. Viscosity test results of scCO2 at different temperatures.

[0095] 60℃, mPa·s 75℃, mPa·s 90℃, mPa·s Example 1 15.3 15.2 15.0 Example 2 15.5 15.3 15.1 Example 3 16.0 15.7 15.5 Example 4 16.5 16.3 16.2 Example 5 16.9 16.7 16.5 Example 6 17.3 17.0 16.8 Example 7 17.6 17.3 17.1 Blank control 0.047 0.044 0.042

[0096] As can be seen from Table 1:

[0097] A. The oil displacement agent products prepared in Examples 1 to 7 of the present invention can achieve a carbon dioxide viscosity increase of 15.3 mPa·s or more at a concentration of 0.5 wt% under conditions of 60°C and 15 MPa, with the highest reaching 17.6 mPa·s (Example 7); while the blank control only achieved a carbon dioxide viscosity increase of 0.047 mPa·s, which is significantly lower than that in Examples 1 to 7.

[0098] B. The oil displacement agent products prepared in Examples 1 to 7 of the present invention can achieve a carbon dioxide viscosity increase of 15.2 mPa·s or more at a concentration of 0.5 wt% under conditions of 75°C and 15 MPa, with the highest reaching 17.3 mmPa·s (Example 7); while the blank control only achieved a carbon dioxide viscosity increase of 0.044 mPa·s, which is significantly lower than that in Examples 1 to 7.

[0099] C. The oil displacement agent products prepared in Examples 1 to 7 of the present invention can increase carbon dioxide viscosity by 15 mPa·s or more at a concentration of 0.5 wt% under conditions of 90°C and 15 MPa, with the highest reaching 17.1 mPa·s (Example 7); while the blank control can increase carbon dioxide viscosity by only 0.042 mPa·s, which is significantly lower than that in Examples 1 to 7.

[0100] In summary, the thickener provided by this invention can increase the viscosity of carbon dioxide and improve its thickening effect. The corresponding oil displacement agent product can achieve a good thickening effect on carbon dioxide at a concentration of 0.5 wt% under the conditions of 60℃~90℃ and 15MPa, which is beneficial to improving the efficiency of carbon dioxide oil displacement.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thickener, characterized in that, The molecular formula of the thickener is: ； Where m takes values ​​from 5000 to 50000, n takes values ​​from 2000 to 50000, and p takes values ​​from 2000 to 50000.

2. A method for preparing the thickener as described in claim 1, characterized in that, Includes the following steps: 2-Trimethylsiloxy-4-allyloxydiphenyl ketone, 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid and xylene were reacted at 70℃~80℃ for 1h~2h in the presence of an initiator, and then the temperature was raised to 90℃~95℃ and the reaction was maintained for 1h~2h to obtain a mixed solution. Mix the mixture with hydroquinone for 15-30 minutes to terminate the reaction; distill under reduced pressure until 1 / 4-1 / 3 of the xylene remains, then stop distillation; cool to precipitate the solid to obtain the thickener.

3. The preparation method according to claim 2, characterized in that, The molar ratio of 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid, and 2-trimethylsiloxy-4-allyloxydiphenyl ketone is (0.5~1):(0.5~1):1; the weight ratio of xylene to 2-trimethylsiloxy-4-allyloxydiphenyl ketone is (20~30):1; and the weight ratio of hydroquinone to 2-trimethylsiloxy-4-allyloxydiphenyl ketone is (0.01~0.02):

1.

4. The preparation method according to claim 2, characterized in that, The weight ratio of the initiator to the 2-trimethylsiloxy-4-allyloxydiphenyl ketone is (0.03~0.06):

1.

5. The preparation method according to claim 4, characterized in that, The initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

6. The preparation method according to claim 2, characterized in that, The cooling precipitation of solids involves first cooling to room temperature, and then adding an additive to precipitate the solids.

7. The preparation method according to claim 6, characterized in that, The weight ratio of the auxiliary agent to the 2-trimethylsiloxy-4-allyloxydiphenyl ketone is (30~40):

1.

8. The preparation method according to claim 7, characterized in that, The adjuvant includes ethanol.

9. An oil displacement agent, characterized in that, The oil displacement agent includes a solubilizer and the thickener as described in claim 1.

10. The oil displacement agent according to claim 9, characterized in that, The mass ratio of the solubilizer to the thickener is 2:1 to 3:

1.

11. The oil displacement agent according to claim 10, characterized in that, The solubilizer includes at least one of propyl acetate, butyl acetate, hexyl acetate, propyl propionate, butyl propionate, and butyl butyrate.

12. A method for preparing an oil displacement agent as described in any one of claims 9 to 11, characterized in that, Includes the following steps: The thickener and the solubilizer are mixed and allowed to stand to obtain the oil displacement agent.

13. The preparation method according to claim 12, characterized in that, The settling time is 12h~24h.

14. The application of the oil displacement agent as described in any one of claims 9 to 11 in enhancing CO2 flooding recovery.

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