Thickening agent, oil-displacing agent as well as preparation method and application of thickening agent and oil-displacing agent

Abstract

The invention discloses a thickening agent, an oil-displacing agent and a preparation method and application thereof, and belongs to the technical field of oil exploitation. The molecular formula of the thickening agent is # imgabs0 #, the value of m ranges from 5000 to 50000, the value of n ranges from 2000 to 50000, and the value of p ranges from 2000 to 50000. The thickening agent can increase the viscosity of the carbon dioxide and improve the tackifying effect of the carbon dioxide, so that the oil displacement efficiency of the carbon dioxide is improved, for example, under the conditions of 60 DEG C and 15 MPa, the tackifying effect of the carbon dioxide can reach more than 15 mPa.s under the concentration of 0.5 wt%.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum extraction, and in particular to a thickener, an oil displacement agent, and a preparation method and application thereof. Background Art

[0002] As the impact of the greenhouse effect becomes increasingly severe, carbon dioxide flooding technology has attracted widespread attention from countries around the world because of its advantages of both oil recovery and emission reduction. Carbon dioxide flooding is an effective tertiary oil recovery technology. Its principle is that when carbon dioxide is dissolved in crude oil in large quantities, it can expand the volume of crude oil, reduce viscosity, and reduce the interfacial tension between oil and water, thereby improving oil recovery efficiency.

[0003] However, the biggest disadvantage of carbon dioxide is that its viscosity is too low under formation conditions. Compared with crude oil, the mobility ratio of the two is too large, which is prone to viscous fingering and crossover, forming an unfavorable mobility ratio. The crossover of carbon dioxide in the reservoir will seriously affect the degree of gas drive to enhance recovery; wells with serious gas crossover, although the oil increase effect is significant, the liquid production is seriously reduced, or even stops; in addition, due to the influence of gravity overburden, during the carbon dioxide displacement process, the gas will cross over to the upper part of the reservoir, forming a crossover channel, resulting in a small gas drive swept volume, which seriously affects the oil recovery effect of carbon dioxide drive and increases the difficulty of sealing the crossover gas.

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

[0005] The object of the present invention is to provide a thickener, an oil displacing agent and a preparation method and application thereof, so as to solve or improve the above technical problems.

[0006] The present invention can be implemented like this:

[0007] In a first aspect, the present invention provides a thickener having a molecular formula of: Among them, the value of m is 5000~50000, the value of n is 2000~50000, and the value of p is 2000~50000.

[0008] In a second aspect, the present invention provides a method for preparing a thickener according to the aforementioned embodiment, comprising the following steps: reacting 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid and xylene at 70° C. to 80° C. for 1 h to 2 h in the presence of an initiator, then heating to 90° C. to 95° C. and reacting for 1 h to 2 h to obtain a mixed solution;

[0009] The mixed solution is mixed with hydroquinone for 15 to 30 minutes to terminate the reaction; distillation is performed under reduced pressure until 1 / 4 to 1 / 3 of the xylene remains, and then the distillation is stopped; the temperature is lowered to precipitate a solid to obtain a thickener.

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

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

[0012] In an alternative 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 auxiliary agent to precipitate solids.

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

[0015] In an alternative embodiment, the adjuvant comprises ethanol.

[0016] In a third aspect, the present invention provides an oil displacing agent, which includes a solubilizing agent and the thickener of the aforementioned embodiment.

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

[0018] In an alternative embodiment, the solubilizing agent includes at least one of 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 displacing agent is 5,000,000 to 10,000,000.

[0020] In a fourth aspect, the present invention provides a method for preparing an oil displacing agent as described in any one of the aforementioned embodiments, comprising the following steps: mixing a thickener and a solubilizing agent, and allowing the mixture to stand to obtain the oil displacing agent.

[0021] In an optional embodiment, the standing time is 12 hours to 24 hours.

[0022] In a fifth aspect, the present invention provides a use of an oil displacement agent as described in any of the aforementioned embodiments in improving CO2 recovery.

[0023] The beneficial effects of the present invention include:

[0024] The thickener in the oil displacement agent of the present invention is a high molecular polymer with 2-trimethylsiloxy-4-propyleneoxy benzophenone, 3-methylcinnamic acid and 2-(trifluoromethyl) acrylic acid as monomers. Among them, 2-trimethylsiloxy-4-propyleneoxy benzophenone can greatly increase the viscosity of CO2, 3-methylcinnamic acid and 2-(trifluoromethyl) acrylic acid contain carboxyl groups, which can entangle with each other to increase the viscosity of the thickener and CO2; 2-(trifluoromethyl) acrylic acid can also increase the solubility of CO2. The thickener can increase the viscosity of carbon dioxide, improve the viscosity-increasing 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 and solubilizer can increase the viscosity of carbon dioxide at a lower dosage, reduce its mobility ratio with crude oil, reduce the escape of carbon dioxide in the oil reservoir, and improve the carbon dioxide oil displacement efficiency. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0027] The thickener, oil displacing agent and preparation method and application thereof provided by the present invention are specifically described below.

[0028] The present invention provides a thickener, the molecular formula of the thickener is: Among them, the value of m is 5000~50000, the value of n is 2000~50000, and the value of p is 2000~50000.

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

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

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

[0032] The thickener is a high molecular polymer with 2-trimethylsiloxy-4-propyleneoxybenzophenone, 3-methylcinnamic acid and 2-(trifluoromethyl)acrylic acid as monomers. Among them, 2-trimethylsiloxy-4-propyleneoxybenzophenone can greatly increase the viscosity of CO2, 3-methylcinnamic acid and 2-(trifluoromethyl)acrylic acid contain carboxyl groups, which can entangle with each other to increase the viscosity of the thickener and CO2; 2-(trifluoromethyl)acrylic acid can also increase the solubility of CO2.

[0033] At 60°C and 15MPa, a concentration of 0.5wt% of the thickener can increase the viscosity of carbon dioxide to 17.6mPa·s.

[0034] Accordingly, the present invention also provides a method for preparing the above-mentioned thickener, which comprises the following steps: in the presence of an initiator, 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid and xylene are first reacted at 70° C. to 80° C. for 1 h to 2 h, then the temperature is raised to 90° C. to 95° C., and the reaction is carried out at this temperature for 1 h to 2 h to obtain a mixed solution;

[0035] The mixed solution is mixed with hydroquinone for 15 to 30 minutes to terminate the reaction; distillation is performed under reduced pressure until 1 / 4 to 1 / 3 of the xylene remains, and then the distillation is stopped; the temperature is lowered to precipitate a solid to obtain a thickener.

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

[0037]

[0038] In some optional embodiments, the molar ratio of 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid and 2-trimethylsilyloxy-4-propyleneoxybenzophenone 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, etc., or other values ​​within the range of (0.5-1):(0.5-1):1.

[0039] The weight ratio of xylene to 2-trimethylsilyloxy-4-propyleneoxybenzophenone may 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] Among them, xylene is a solvent required for polymer polymerization. If the amount of xylene used is too little, it will cause explosion and affect product quality; if the amount of xylene used is too much, it will reduce the production efficiency.

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

[0042] Among them, hydroquinone is used as a terminator for the polymerization chain reaction. If the amount of hydroquinone used is too little, it is not conducive to the termination of the polymerization chain reaction; if the amount of hydroquinone used is too much, it is easy to cause waste.

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

[0044] The initiator may illustratively but not limitatively include at least one of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide.

[0045] In some optional embodiments, cooling to precipitate solids includes: first cooling to room temperature, and then adding an auxiliary agent to precipitate solids. The auxiliary agent is mainly used to precipitate solids.

[0046] The weight ratio of the auxiliary agent to 2-trimethylsilyloxy-4-propyleneoxybenzophenone may 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] The adjuvant may illustratively but not limitedly include ethanol.

[0048] In addition, the present invention also provides an oil-displacing agent, which comprises a solubilizing agent and the above-mentioned thickening agent.

[0049] In some optional embodiments, the mass ratio of the solubilizer to the thickener may 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 solubilizing agent may illustratively but not limitatively include at least one of propyl acetate, butyl acetate, hexyl acetate, propyl propionate, butyl propionate and butyl butyrate.

[0051] The use of the above solubilizer can greatly improve the solubility of CO2 in the thickener. However, if the amount of solubilizer is too much, the viscosity of the product will decrease and the oil displacement effect will decrease.

[0052] In some optional embodiments, the viscosity average molecular weight of the oil displacing agent may be 5,000,000 to 10,000,000.

[0053] Correspondingly, the present invention also provides a method for preparing the above oil-displacing agent, which comprises the following steps: mixing a thickener and a solubilizing agent, and allowing the mixture to stand to obtain the oil-displacing agent.

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

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

[0056] The above oil displacement agent can increase the viscosity of carbon dioxide under the condition of lower dosage, reduce its mobility ratio with crude oil, reduce the escape of carbon dioxide in the oil reservoir, and improve the efficiency of carbon dioxide oil displacement.

[0057] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0058] Example 1

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

[0060] (1) 0.02 mol of 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 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-trimethylsilyloxy-4-propyleneoxybenzophenone is about 19.9:1) were added to the reactor in sequence, the reactor and pipeline were purged with nitrogen for 5 min to replace the air, and the mixture was stirred to dissolve, 0.2 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.03:1) was added, the temperature was slowly raised to 70° C., the mixture was kept at this temperature for reaction for 1 h, and the temperature was further raised to 90° C., the mixture was kept at this temperature for reaction for 1 h to obtain a viscous mixed solution.

[0061] (2) 0.07 g of hydroquinone (the weight ratio of hydroquinone to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.01:1) is added to the mixed solution, and stirring is continued for 15 min to terminate the reaction; the mixed solution is distilled under reduced pressure, and the distillation is stopped when 1 / 3 of the xylene remains; the mixture is cooled to room temperature, and 195.9 g of ethanol (the weight ratio of ethanol to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 30:1) is added to precipitate a solid, which is filtered and dried to obtain a thickener.

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

[0063] Example 2

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

[0065] (1) 0.02 mol of 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 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-trimethylsilyloxy-4-propyleneoxybenzophenone is about 22.2:1) were added to the reactor in sequence, the reactor and pipeline were purged with nitrogen for 6 min to replace the air, and the mixture was stirred to dissolve, 0.24 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.036:1) was added, the temperature was slowly raised to 80° C., the mixture was kept at this temperature for 2 h, and the temperature was further raised to 92° C., the mixture was kept at this temperature for 1 h, and a viscous mixed solution was obtained.

[0066] (2) 0.08 g of hydroquinone (the weight ratio of hydroquinone to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.012:1) is added to the mixed solution, and stirring is continued for 25 min. The reaction is terminated and the mixed solution is distilled under reduced pressure. When 1 / 3 of the xylene remains, the distillation is stopped and the mixture is cooled to room temperature. 214 g of ethanol (the weight ratio of ethanol to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 32.8:1) is added to precipitate a solid, which is filtered and dried to obtain a thickener.

[0067] (3) 5 g of thickener and 14 g of butyl acetate were mixed and allowed to stand for 12 h to obtain a product oil displacement agent.

[0068] Example 3

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

[0070] (1) 0.02 mol of 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 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-trimethylsilyloxy-4-propyleneoxybenzophenone is about 23.7:1) were added to the reactor in sequence, the reactor and pipeline were purged with nitrogen for 8 min to replace the air, and the mixture was stirred to dissolve, and 0.28 g of azobisisoheptanenitrile (the weight ratio of azobisisoheptanenitrile to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.04:1) was added, the temperature was slowly raised to 75° C., and the mixture was kept at this temperature for reaction for 1 h, and the temperature was further raised to 93° C. and the mixture was kept at this temperature for reaction for 2 h to obtain a viscous mixed solution.

[0071] (2) 0.09 g of hydroquinone (the weight ratio of hydroquinone to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.013:1) is added to the mixed solution, and stirring is continued for 20 min. The reaction is terminated and the mixed solution is distilled under reduced pressure. When 1 / 4 of the xylene remains, the distillation is stopped, the temperature is cooled to room temperature, and 226 g of ethanol (the weight ratio of ethanol to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 34.6:1) is added to precipitate a solid, which is filtered and dried to obtain a thickener.

[0072] (3) 5 g of thickener and 12.6 g of hexyl acetate were mixed and allowed to stand for 20 h to obtain a product oil displacement agent.

[0073] Example 4

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

[0075] (1) 0.02 mol of 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 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-trimethylsilyloxy-4-propyleneoxybenzophenone is about 24.5:1) were added to the reactor in sequence, the reactor and pipeline were purged with nitrogen for 10 min to replace the air, and the mixture was stirred to dissolve, 0.3 g of azobisisoheptanenitrile (the weight ratio of azobisisoheptanenitrile to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.046:1) was added, the temperature was slowly raised to 72° C., the mixture was kept warm for reaction for 2 h, and the temperature was further raised to 94° C., the mixture was kept warm for reaction for 1.5 h to obtain a viscous mixed solution.

[0076] (2) 0.1 g of hydroquinone (the weight ratio of hydroquinone to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.015:1) was added to the mixed solution, and stirring was continued for 30 min. The reaction was terminated and the mixed solution was distilled under reduced pressure. When 1 / 4 of the xylene remained, the distillation was stopped and the mixture was cooled to room temperature. 238 g of ethanol (the weight ratio of ethanol to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 36.45:1) was added to precipitate a solid, which was filtered and dried to obtain a thickener.

[0077] (3) 5 g of thickener and 13.6 g of propyl propionate were mixed and allowed to stand for 18 h to obtain an oil displacement agent.

[0078] Example 5

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

[0080] (1) 0.02 mol of 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 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-trimethylsilyloxy-4-propyleneoxybenzophenone is about 26.9:1) were added to the reactor in sequence, the reactor and pipeline were purged with nitrogen for 8 min to replace the air, and the mixture was stirred to dissolve, and 0.36 g of azobisisobutyronitrile (the weight ratio of azobisisobutyronitrile to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.055:1) was added, the temperature was slowly raised to 76° C., and the mixture was kept warm for reaction for 1.5 h, and the temperature was further raised to 91° C. and the mixture was kept warm for reaction for 1.6 h to obtain a viscous mixed solution.

[0081] (2) 0.12 g of hydroquinone (the weight ratio of hydroquinone to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.018:1) is added to the mixed solution, and stirring is continued for 20 min. The reaction is terminated and the mixed solution is distilled under reduced pressure. When 1 / 3 of the xylene remains, the distillation is stopped, the mixture is cooled to room temperature, and 256 g of ethanol (the weight ratio of ethanol to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 39.2:1) is added to precipitate a solid, which is filtered and dried to obtain a thickener.

[0082] (3) 5 g of thickener and 11.8 g of butyl propionate were mixed and allowed to stand for 16 h to obtain an oil displacement agent.

[0083] Example 6

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

[0085] (1) 0.02 mol of 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 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-trimethylsilyloxy-4-propyleneoxybenzophenone is about 28.2:1) were added to a reactor in sequence, the reactor and pipeline were purged with nitrogen for 10 min to replace the air, and the mixture was stirred to dissolve, 0.32 g of benzoyl peroxide (the weight ratio of benzoyl peroxide to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.049:1) was added, the temperature was slowly raised to 77° C., the mixture was kept warm for reaction for 1.2 h, and the temperature was further raised to 94° C., the mixture was kept warm for reaction for 1.2 h to obtain a viscous mixed solution.

[0086] (2) 0.12 g of hydroquinone (the weight ratio of hydroquinone to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.018:1) was added to the mixed solution, and stirring was continued for 25 min. The reaction was terminated and the mixed solution was distilled under reduced pressure. When 1 / 3 of the xylene remained, the distillation was stopped and the mixture was cooled to room temperature. 247 g of ethanol (the weight ratio of ethanol to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 37.8:1) was added to precipitate a solid, which was filtered and dried to obtain a thickener.

[0087] (3) 5 g of thickener and 10.9 g of butyl butyrate were mixed and allowed to stand for 21 h to obtain an oil displacement agent.

[0088] Example 7

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

[0090] (1) 0.02 mol of 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 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-trimethylsilyloxy-4-propyleneoxybenzophenone is about 29.9:1) were added to the reactor in sequence, the reactor and pipeline were purged with nitrogen for 7 minutes to replace the air, and the mixture was stirred to dissolve, and 0.39 g of azobenzoyl peroxide (the weight ratio of azobenzoyl peroxide to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.06:1) was added, the temperature was slowly raised to 75° C., the mixture was kept warm for reaction for 1.8 hours, and the temperature was further raised to 95° C., the mixture was kept warm for reaction for 1.3 hours to obtain a viscous mixed solution.

[0091] (2) 0.13 g of hydroquinone (the weight ratio of hydroquinone to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 0.02:1) was added to the mixed solution, and stirring was continued for 30 min. The reaction was terminated and the mixed solution was distilled under reduced pressure. When 1 / 4 of the xylene remained, the distillation was stopped, the temperature was cooled to room temperature, and 260.8 g of ethanol (the weight ratio of ethanol to 2-trimethylsilyloxy-4-propyleneoxybenzophenone is about 39.9:1) was added to precipitate a solid, which was filtered and dried to obtain a thickener.

[0092] (3) 5 g of thickener and 10 g of propyl acetate were mixed and allowed to stand for 24 h to obtain an oil displacement agent product.

[0093] The oil displacement agent products prepared in Examples 1 to 7 of the present invention were dissolved in carbon dioxide to a concentration of 0.5 wt %, placed in a pressure-resistant, temperature-controlled closed Haake rheometer, stirred evenly, and the shear rate was adjusted to 170 s -1 The system was heated stepwise at a pressure of 15 MPa to test the viscosity of supercritical carbon dioxide (scCO2) at 60°C, 75°C, and 90°C, with carbon dioxide as a blank control. The test results are shown in Table 1.

[0094] Table 1 scCO2 viscosity test results 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] From Table 1 we can see that:

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

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

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

[0100] In summary, the thickener provided by the present invention can increase the viscosity of carbon dioxide and improve the viscosity-increasing effect of carbon dioxide. The corresponding oil-displacing agent product can make carbon dioxide have a good viscosity-increasing effect at a concentration of 0.5wt% under the conditions of 60°C to 90°C and 15MPa, which is beneficial to improving the efficiency of carbon dioxide oil displacement.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A thickener, characterized in that The molecular formula of the thickener is: Among them, the value of m is 5000~50000, the value of n is 2000~50000, and the value of p is 2000~50000.

2. A method for preparing a thickener as claimed in claim 1, characterized in that: The following steps are involved: 2-trimethylsilyloxy-4-propyleneoxybenzophenone, 3-methylcinnamic acid, 2-(trifluoromethyl)acrylic acid and xylene are firstly reacted at 70°C to 80°C for 1h to 2h in the presence of an initiator, and then the temperature is raised to 90°C to 95°C and the reaction is carried out at this temperature for 1h to 2h to obtain a mixed solution; The mixed solution is mixed with hydroquinone for 15 to 30 minutes to terminate the reaction; distillation is performed under reduced pressure until 1 / 4 to 1 / 3 of the xylene remains, and then the distillation is stopped; the temperature is lowered to precipitate a solid to obtain a thickener.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the 3-methylcinnamic acid, the 2-(trifluoromethyl)acrylic acid and the 2-trimethylsilyloxy-4-propyleneoxybenzophenone is (0.5-1):(0.5-1):1; the weight ratio of the xylene and the 2-trimethylsilyloxy-4-propyleneoxybenzophenone is (20-30):1; the weight ratio of the hydroquinone and the 2-trimethylsilyloxy-4-propyleneoxybenzophenone 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-trimethylsilyloxy-4-propyleneoxybenzophenone is (0.03-0.06):1; Preferably, the initiator comprises at least one of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide.

5. The preparation method according to claim 2, characterized in that: Cooling down to precipitate solids includes: first cooling down to room temperature, then adding an auxiliary agent to precipitate solids; Preferably, the weight ratio of the auxiliary agent to the 2-trimethylsilyloxy-4-propyleneoxybenzophenone is (30-40):1; Preferably, the auxiliary agent comprises ethanol.

6. An oil displacing agent, characterized in that: The oil displacing agent comprises a solubilizer and the thickener according to claim 1.

7. The oil-displacing agent according to claim 6, characterized in that The mass ratio of the solubilizer to the thickener is 2:1 to 3:1; Preferably, the solubilizing agent includes at least one of propyl acetate, butyl acetate, hexyl acetate, propyl propionate, butyl propionate and butyl butyrate.

8. The oil-displacing agent according to claim 6 or 7, characterized in that The viscosity average molecular weight of the oil displacing agent is 5,000,000 to 10,000,000.

9. A method for preparing an oil displacing agent according to any one of claims 6 to 8, characterized in that: The method comprises the following steps: mixing the thickener and the solubilizing agent, and allowing the mixture to stand to obtain the oil displacing agent; Preferably, the standing time is 12 h to 24 h.

10. Use of the oil displacement agent according to any one of claims 6 to 8 in improving CO2 flooding recovery.

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