Carbon dioxide tackifier as well as preparation method and application thereof

Abstract

The invention discloses a carbon dioxide tackifier as well as a preparation method and application thereof. The carbon dioxide tackifier comprises an amino compound and a second compound, and the second compound is at least one of the following compounds: an ether bond-containing compound and an ester bond-containing compound. After the carbon dioxide tackifier is added, the viscosity is improved by more than 10 times compared with that of pure carbon dioxide, so that the sweep efficiency of carbon dioxide can be effectively increased, and the recovery efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of enhanced oil recovery, and specifically relates to a carbon dioxide viscosifier and its preparation method and application. Background Art

[0002] Injecting the recycled CO 2 into the oil and gas reservoir to improve the crude oil recovery rate can not only store CO 2 for a long time to fulfill the emission reduction obligation, but also better improve the recovery rate to obtain economic benefits, successfully transforming its "harm in the sky" into "treasure in the ground". During the CO 2 displacement process, there are serious technical problems, that is, due to the large viscosity contrast between the underground crude oil and the injected CO 2 , an unfavorable mobility ratio is caused, resulting in early CO 2 breakthrough, reduced reservoir sweep efficiency, and reduced oil production.

[0003] Therefore, in order to achieve good CO 2 oil displacement effect, it is necessary to control gas channeling, adjust the gas injection profile, expand the gas sweep area, enable CO 2 to contact the remaining oil to the maximum extent to improve the oil washing efficiency, and ultimately achieve the purpose of economically and efficiently improving the recovery rate. Developing a viscosifier and dissolving it in CO 2 to increase the viscosity of the mobile phase CO 2 to achieve the purpose of mobility control has attracted much attention.

[0004] Due to the low dielectric constant ε (1.0–1.6) and the unit volume polarization rate α / v of supercritical CO 2 , it is a very weak solvent for most non-volatile solutes. Therefore, the low solubility of high molecular compounds in carbon dioxide makes it impossible to effectively increase viscosity. For example, polyvinyl acetate is a polymer relatively compatible with carbon dioxide and can interact with multiple CO 2 molecular sites. Even so, for PVAc with a degree of polymerization of 8000, the pressure required to dissolve 5 wt% at room temperature is as high as 75 MPa, and the viscosity increasing effect is not obvious. In addition, the use of a large amount of cosolvents (toluene or others, 10–50%) has greatly increased the cost.

[0005] Therefore, there is an urgent need for a viscosifier that can effectively increase the viscosity of carbon dioxide at present. Summary of the Invention

[0006] To solve the problem of low viscosity of carbon dioxide and easy channeling during the oil displacement process in the prior art, the present invention provides a carbon dioxide viscosifier and its preparation method and application. After adding the viscosifier, the viscosity is increased by more than 10 times compared with pure carbon dioxide, thereby expanding the carbon dioxide sweep coefficient and improving the recovery rate.

[0007] One of the objectives of the present invention is to provide a carbon dioxide thickening agent, which comprises an amino compound and a second compound, and the second compound is at least one of the following compounds: an ether bond-containing compound and an ester bond-containing compound.

[0008] In a preferred embodiment of the present invention,

[0009] the amino compound is at least one of compounds having an amino structure containing a primary amine and / or a secondary amine. Preferably, the part connected to the amino group in the amino compound is at least one of a fluorinated polyacrylate group, a polysiloxane group, a long-chain hydrocarbon group, and a fluorinated alkyl group, and is preferably at least one of a fluorinated polyacrylate group and a polysiloxane group; and / or,

[0010] the total number of ether bonds and ester bonds in the second compound is at least two.

[0011] In a preferred embodiment of the present invention,

[0012] when the part connected to the amino group is a fluorinated polyacrylate group, the structure of the amino compound is as shown in the following formula (I):

[0013]

[0014] wherein, R 1 is one of -H, -CH 3 、-CH 2 CH 3 、-CH 2 CH 2 CH 3 、-CH 2 OH、-C 2 H 4 OH、-C 3 H 6 OH; R 3 is a fluorinated alkyl group of C 4 -C 12 , preferably a fluorinated alkyl group of C 8 -C 12 , more preferably perfluorohexylethyl; and the ratio of H to F in R 3 is (0 - 0.5):1; R 4 is -H or -CH 3 , R 5 is an alkylene group or a carbonyl group of C 1 -C 5 ; m:n = 1:(0.1 - 1), preferably m:n = 1:(0.1 - 0.3); when the part connected to the amino group is a fluorinated polyacrylate group, the number-average molecular weight of the amino compound is 1000 - 10000, preferably 4000 - 7000. m represents the structural unit The average degree of polymerization, and n represents the structural unit The average degree of polymerization; in formula (I), the structural unit And the structural unit Are randomly arranged.

[0015] When the part connected to the amino group is a fluorinated polyacrylate group, the amino compound can be obtained commercially or prepared by any method disclosed in the prior art in this field.

[0016] In a preferred embodiment of the present invention,

[0017] When the part connected to the amino group is a polysiloxane group, the structure of the amino compound is shown in the following formula (II):

[0018]

[0019] Wherein, R 1 Is -H, -CH 3 、-CH 2 CH 3 、-CH 2 CH 2 CH 3 、-CH 2 OH、-C 2 H 4 OH、-C 3 H 6 OH; R 6 Is an alkylene group or an ester group of C 1 -C 5 ; p:q = 1:(0.1 - 0.5), preferably p:q = 1:(0.1 - 0.3); when the part connected to the amino group is a polysiloxane group, the number average molecular weight of the amino compound is 1000 - 20000, preferably 6000 - 10000. p represents the average degree of polymerization of the structural unit And q represents the average degree of polymerization of the structural unit ; in formula (II), the structural unit And the structural unit Are randomly arranged.

[0020] When the part connected to the amino group is a polysiloxane group, the amino compound can be obtained commercially or prepared by any method disclosed in the prior art in this field, and it is preferably prepared by referring to the method in the reference "Li Mingtao, An Qiufeng, Hu Liangwei. Synthesis, Characterization and Application Performance of N-Cyclohexyl-γ-aminopropyl Polydimethylsiloxane [J]. Fine Chemicals, 2006, 23(4):4. DOI: 10.3321 / j.issn:1003-5214.2006.04.022.".

[0021] In a preferred embodiment of the present invention,

[0022] When the part connected to the amino group is a long-chain hydrocarbon group, the structure of the amino compound is shown in the following formula (III):

[0023] R 7 NHR 1 Formula (III);

[0024] Wherein, R 7 is an aliphatic hydrocarbon group of C 10 -C 24 Preferably, it is an aliphatic hydrocarbon group of C 10 -C 20 ; R 1 is -H, -CH 3 -CH 2 CH 3 -CH 2 CH 2 CH 3 -CH 2 OH, -C 2 H 4 OH, -C 3 H 6 OH.

[0025] When the part connected to the amino group is a long-chain hydrocarbon group, the amino compound can be obtained commercially or prepared by any method disclosed in the prior art in this field.

[0026] In the present invention, unless otherwise specifically defined, the aliphatic hydrocarbon group refers to aliphatic alkyl and alkenyl groups, particularly straight-chain or branched-chain alkyl and straight-chain or branched-chain alkenyl groups. The number of carbon atoms in the aliphatic hydrocarbon group can be 10-24, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24.

[0027] In a preferred embodiment of the present invention,

[0028] When the part connected to the amino group is a fluoroalkyl group, the structure of the amino compound is shown in the following formula (IV):

[0029] R 8 NHR 1 Formula (IV);

[0030] Wherein, R 8 is a perfluorinated or partially fluorinated C 6 -C 24 alkyl group, preferably a perfluorinated or partially fluorinated C 6 -C 20an alkyl group, and R 8 in which the ratio of H to F is less than or equal to 1:1; R 1 is -H, -CH 3 -, -CH 2 CH 3 -, -CH 2 CH 2 CH 3 -, -CH 2 OH, -C 2 H 4 OH, -C 3 H 6 OH, etc.

[0031] When the part connected to the amino group is a fluoroalkyl group, the amino compound can be obtained commercially or prepared by any method disclosed in the prior art in this field.

[0032] In a preferred embodiment of the present invention,

[0033] The ether bond-containing compound is at least one of the compounds represented by formula (V):

[0034] and / or,

[0035] The ester bond-containing compound is at least one of the compounds represented by formula (VI):

[0036]

[0037] In the above formula (V) and formula (VI), R 9 and R 10 are each independently an alkyl group or an aryl group of C 1 -C 6 ; R 9 and R 10 are each independently an alkyl group or an aryl group of C 1 -C 6 ; R 2 are each independently an alkylene group of C 1 -C 3 , a substituted alkylene group of C 1 -C 3 or -R 11 OR 12 -, where R 11 and R 12 are each independently an alkyl group or an aryl group of C 1 -C 6 ; Preferably, the substituent in the substituted alkylene group of C 1 -C 3 is C 1 -C 6alkyl or aryl or C 1 -C 6 alkyl or aryl-substituted ester group.

[0038] In a preferred embodiment of the present invention,

[0039] the second compound is selected from at least one of the compounds represented by formula (VI).

[0040] In a preferred embodiment of the present invention,

[0041] the molar ratio of the amino compound to the second compound is 1:(0.5 - 10), preferably 1:(0.5 - 6).

[0042] A second object of the present invention is to provide a method for preparing a carbon dioxide viscosity increasing agent according to one of the objects of the present invention, including the step of fully mixing components including the amino compound and the second compound.

[0043] In a preferred embodiment of the present invention,

[0044] the conditions for the full mixing include: mixing for 1 - 120 min under the condition that the stirring speed is 50 - 1000 rpm.

[0045] A third object of the present invention is to provide a method for increasing the viscosity of carbon dioxide, including mixing the carbon dioxide viscosity increasing agent according to one of the objects of the present invention or the carbon dioxide viscosity increasing agent obtained by the preparation method according to the second object of the present invention with carbon dioxide; preferably, the method includes the step of alternately or jointly injecting the carbon dioxide viscosity increasing agent and carbon dioxide or first mixing the carbon dioxide viscosity increasing agent with carbon dioxide and then injecting it into a porous medium containing crude oil, and more preferably, the carbon dioxide is supercritical and / or liquid carbon dioxide.

[0046] In a preferred embodiment of the present invention,

[0047] the hydrogen group in the amino compound and the oxygen group in the second compound associate in carbon dioxide to form an aggregate.

[0048] The amino compound and the second compound associate in carbon dioxide to form the following structure:

[0049]

[0050] wherein, R 1 are each independently -H, -CH 3 , -CH 2 CH 3 , -CH 2 CH 2 CH 3 , -CH 2OH, -C 2 H 4 OH or -C 3 H 6 OH; R 2 is C 1 -C 3 an alkylene group of -C 1 -C 3 an alkylene group of -C 11 or -R 12 OR 11 -, where R 12 and R 1 are each independently an alkyl group or an aryl group of C 6 -C 1 -C 3 ; preferably, the substituent in the alkylene group of the substituted C 1 -C 6 is an alkyl group or an aryl group of C 1 -C 6 or an ester group substituted by an alkyl group or an aryl group of C represents the part connected to the amine group in the amine compound; represents the part connected to -O- in the second compound.

[0051] In a preferred embodiment of the present invention,

[0052] the volume ratio of the carbon dioxide viscosifier to carbon dioxide is (0.1 - 5):100, preferably (0.3 - 3):100.

[0053] The present invention can adopt the following specific technical solutions:

[0054] The method for increasing the viscosity of carbon dioxide includes alternately or jointly injecting the carbon dioxide viscosifier and carbon dioxide or first mixing it with carbon dioxide and then injecting it into the porous medium containing crude oil to increase the viscosity of carbon dioxide and expand the sweep efficiency of carbon dioxide, thereby improving the recovery factor.

[0055] The fourth object of the present invention is to provide an application of the carbon dioxide viscosifier of one of the objects of the present invention or the carbon dioxide viscosifier obtained by the preparation method of the second object of the present invention in increasing the viscosity of carbon dioxide.

[0056] The present invention has the following advantages:

[0057] In the amine compound of the present invention, the amine group is a primary amine and a secondary amine, and the hydrogen atoms therein can have intermolecular hydrogen bond interactions with the oxygen atoms in the ester bond or ether bond, so that two molecules associate with each other. The part connected to the amine group has a strong affinity for carbon dioxide, which promotes its dissolution in carbon dioxide. By controlling the molecular weight and the ratio of the two, larger aggregates are formed in supercritical or liquid carbon dioxide, restricting the movement of carbon dioxide, thereby increasing the viscosity of carbon dioxide. Detailed implementation mode

[0058] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the content of the present invention still fall within the protection scope of the present invention.

[0059] In the embodiments of the present invention, except for the raw materials whose synthesis methods have been noted, other raw materials used are all conventional commercially available raw materials. In the embodiments of the present invention, the number average molecular weight of the amine compound is determined by gel chromatography, and the average degree of polymerization of each structural unit in the amine compound is obtained by nuclear magnetic resonance hydrogen spectrum testing.

[0060] Example 1

[0061] Preparation of amino silicone:

[0062] In a 500 mL three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 120 g of octamethylcyclotetrasiloxane, 2 g of hexamethyldisiloxane, 21 g of 3-aminopropylmethyldimethoxysilane, and 0.2 g of tetramethylammonium hydroxide catalyst were successively added. Nitrogen was passed for protection, stirred and mixed evenly, heated to 120 °C, reacted for 4 hours, and equilibrated at 135 °C for 2 hours. The product was evacuated under reduced pressure for 30 min and then cooled to room temperature to obtain a transparent viscous liquid, namely amino silicone (poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane]).

[0063] The structure of amino silicone (poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane]) is as follows:

[0064] Among them, R 1 is H, R 6 =-C 3 H 6 -; The chemical shifts (δ) obtained by nuclear magnetic resonance hydrogen spectrum testing (using deuterated chloroform as the solvent) from high field to low field are in turn: δ H1 0.02 (methyl hydrogen atoms on the silicone), δ H2 0.45 (methylene hydrogen atoms on the silicone), δ H31.42 (the hydrogen atom of the methylene group meta to the nitrogen atom) and δ H4 2.60 (the hydrogen atom of the methylene group connected to the nitrogen atom), and by integrating the above hydrogen atoms, p:q = 3.5:1; the number-average molecular weight Mn = 8724 was measured by GPC.

[0065] Preparation of the carbon dioxide viscosity enhancer:

[0066] The above amino silicone (poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane]) and glyceryl tripropionate were mixed at a molar ratio of 1:5 under stirring at 300 rpm for 30 min to obtain the carbon dioxide viscosity enhancer.

[0067] First, supercritical carbon dioxide was injected into a 1 / 16-inch stainless steel capillary at an injection rate of 5 mL / min, the temperature was controlled at 40 °C, and the back pressure was 40 MPa. A differential pressure gauge was used to measure and record the differential pressure ΔP at the front and rear ends at injection equilibrium. 0 The above carbon dioxide viscosity enhancer and supercritical carbon dioxide were co-injected into a 1 / 16-inch stainless steel capillary. The injection rate of supercritical carbon dioxide was 4.9 mL / min, and the injection rate of the carbon dioxide viscosity enhancer was 0.10 mL / min. The temperature was controlled at 40 °C, and the back pressure was 40 MPa. A differential pressure gauge was used to measure and record the differential pressure ΔP at the front and rear ends at injection equilibrium. 1 。

[0068] Calculate the viscosity increase multiple R of supercritical carbon dioxide according to the above differential pressure

[0069] R = ΔP 1 / ΔP 0

[0070] The experimental results showed that: ΔP 0 = 1.8, ΔP 1 = 28.9, R = 16.1

[0071] After adding the carbon dioxide viscosity enhancer, the viscosity of supercritical carbon dioxide increased to 16.1 times.

[0072] Comparative Example 1

[0073] The amino silicone obtained in Example 1 above and supercritical carbon dioxide were co-injected into a 1 / 16-inch stainless steel capillary. The injection rate of supercritical carbon dioxide was 4.9 mL / min, and the injection rate of the amino silicone was 0.10 mL / min. The temperature was controlled at 40 °C, and the back pressure was 40 MPa. A differential pressure gauge was used to measure and record the differential pressure ΔP at the front and rear ends at injection equilibrium. 1-1 。

[0074] Inject the above-mentioned glyceryl tripropionate and supercritical carbon dioxide into a 1 / 16-inch stainless steel capillary together. The injection rate of supercritical carbon dioxide is 4.9 mL / min, and the injection rate of glyceryl tripropionate is 0.10 mL / min. Control the temperature at 40 °C and the back pressure at 40 MPa. Use a differential pressure gauge to test and record the differential pressure ΔP at the front and rear ends at the injection equilibrium. 1-2 。

[0075] The experimental results show that: ΔP 1-1 = 5.5, ΔP 1-1 = 2.0,

[0076] The calculation process is the same as that in Example 1. After adding amino silicone and glyceryl tripropionate respectively, the viscosity of supercritical carbon dioxide increases to 3.1 and 1.1 times.

[0077] Example 2

[0078] Preparation of amino fluorinated polyacrylate A:

[0079] Stir 1 mol of perfluorohexylethyl acrylate, 0.2 mol of 3-amino-1-propene, and 5 mol of tetrahydrofuran into a homogeneous solution. Add the above solution to a reaction kettle equipped with a condensing reflux device, purge with nitrogen for 30 min, add azobisisobutyronitrile to the reaction kettle, continuously purge with nitrogen, maintain the system temperature at 50 °C in a water bath, carry out condensing reflux, and react for 6 hours. Remove the solvent by vacuum drying to obtain amino fluorinated polyacrylate A, with a total yield of 97%.

[0080] The structure of amino fluorinated polyacrylate A is as follows:

[0081] Among them, R 1 is -H; R 3 is -C 8 H 4 F 13 ; R 4 is -H, R 5 is -CH 2 -; Test its m:n = 1:0.2 by nuclear magnetic resonance hydrogen spectrum; Test its number average molecular weight to be 5130 by GPC.

[0082] Preparation of carbon dioxide thickening agent:

[0083] Mix the above-synthesized amino fluorinated polyacrylate A and glyceryl tributyrate at a molar ratio of 1:3 under stirring at 300 rpm for 30 min to obtain a carbon dioxide thickening agent.

[0084] The above carbon dioxide thickener was mixed with supercritical carbon dioxide at a volume ratio of 1.5:100, and then injected into a 1 / 16-inch stainless steel capillary. The injection rate of the mixture was 5.0 mL / min, the temperature was controlled at 40 °C, and the back pressure was 40 MPa. A differential pressure gauge was used to measure and record the differential pressure ΔP at the front and rear ends at injection equilibrium. 2 。

[0085] The experimental results showed that: ΔP 2 = 33.7, R = 18.7

[0086] The calculation process was the same as that in Example 1. After adding the carbon dioxide thickener, the viscosity of supercritical carbon dioxide increased to 18.7 times.

[0087] Comparative Example 2

[0088] The above amino fluorinated polyacrylate A was mixed with supercritical carbon dioxide at a volume ratio of 1.5:100, and then injected into a 1 / 16-inch stainless steel capillary. The injection rate of the mixture was 5.0 mL / min, the temperature was controlled at 40 °C, and the back pressure was 40 MPa. A differential pressure gauge was used to measure and record the differential pressure ΔP at the front and rear ends at injection equilibrium. 2-1 。

[0089] The above tributyrin was mixed with supercritical carbon dioxide at a ratio of 1.5:100, and then injected into a 1 / 16-inch stainless steel capillary. The injection rate of the mixture was 5.0 mL / min, the temperature was controlled at 40 °C, and the back pressure was 40 MPa. A differential pressure gauge was used to measure and record the differential pressure ΔP at the front and rear ends at injection equilibrium. 2-1 。

[0090] The experimental results showed that: ΔP 1-1 = 11.0, ΔP 1-1 = 2.3,

[0091] The calculation process was the same as that in Example 1. After adding amino fluorinated polyacrylate A and tributyrin respectively, the viscosity of supercritical carbon dioxide increased to 6.1 and 1.3 times.

[0092] Example 3

[0093] Preparation of carbon dioxide thickener:

[0094] The amino fluorinated polyacrylate A synthesized in Example 2 was mixed with dipropylene glycol dimethyl ether at a molar ratio of 1:2 and stirred at 300 rpm for 30 min to obtain a carbon dioxide thickener.

[0095] After mixing the above carbon dioxide thickening agent with supercritical carbon dioxide at a volume ratio of 3:100, it is injected into a 1 / 16-inch stainless steel capillary. The injection rate of the mixture is 5.0 mL / min, the temperature is controlled at 40 °C, and the back pressure is 40 MPa. A differential pressure gauge is used to measure and record the differential pressure ΔP at the front and rear ends at the injection equilibrium. 2 。

[0096] The experimental results show that: ΔP 2 = 40.0, R = 22.2

[0097] The calculation process is the same as that in Example 1. After adding the carbon dioxide thickening agent, the viscosity of supercritical carbon dioxide is increased to 22.2 times.

[0098] Example 4

[0099] Preparation of amino fluorinated polyacrylate B:

[0100] 1 mol of 2-(perfluorodecyl)ethyl methacrylate, 0.15 mol of acrylamide, and 6 mol of tetrahydrofuran are stirred into a uniform solution. The above solution is added to a reaction kettle equipped with a condensing reflux device, and nitrogen is passed through to remove oxygen for 30 min. Azodiisobutyronitrile is added to the reaction kettle, and nitrogen is continuously passed through. The temperature of the system is maintained at 50 °C in a water bath, with condensing reflux, and the reaction lasts for 5 hours. The solvent is removed by vacuum drying to obtain amino fluorinated polyacrylate B, and the total yield is 98%.

[0101] The structure of amino fluorinated polyacrylate B is as follows:

[0102] Among them, R 1 is -H; R 3 is -C 12 H 4 F 21 ; R 4 is -CH 3 and R 5 is C=O; its m:n = 1:0.15 is tested by nuclear magnetic resonance hydrogen spectrum; its number average molecular weight is 6089 is tested by GPC.

[0103] Preparation of carbon dioxide thickening agent:

[0104] The above-synthesized amino fluorinated polyacrylate B and tributyrin are mixed at a molar ratio of 1:1 under stirring at 300 rpm for 30 min to obtain a carbon dioxide thickening agent.

[0105] After mixing the above carbon dioxide thickening agent with supercritical carbon dioxide at a volume ratio of 1:100, it is injected into a 1 / 16-inch stainless steel capillary. The injection rate of the mixture is 5.0 mL / min, the temperature is controlled at 40 °C, and the back pressure is 40 MPa. A differential pressure gauge is used to measure and record the differential pressure ΔP at the front and rear ends at injection equilibrium. 2 .

[0106] The experimental results show that: ΔP 2 = 29.3, R = 16.3

[0107] The calculation process is the same as that in Example 1. After adding the carbon dioxide thickening agent, the viscosity of supercritical carbon dioxide is increased to 16.3 times.

[0108] It can be seen from Examples 1-4 and Comparative Examples 1-2 that: after adding the carbon dioxide thickening agent of the present invention, the viscosity is increased by more than 10 times, preferably more than 15 times, compared with pure carbon dioxide, thereby effectively expanding the carbon dioxide sweep efficiency and improving the recovery rate.

Claims

1. A carbon dioxide viscosifier, comprising an amino compound and a second compound, wherein the second compound is at least one of the following compounds: an ether bond-containing compound, an ester bond-containing compound.

2. The carbon dioxide viscosifier according to claim 1, characterized in that: the amino compound is at least one of compounds having an amino structure containing a primary amine and / or a secondary amine. Preferably, the part connected to the amino group in the amino compound is at least one of a fluorinated polyacrylate group, a polysiloxane group, a long-chain hydrocarbon group, and a fluorinated alkyl group, and preferably is at least one of a fluorinated polyacrylate group and a polysiloxane group; and / or, the total number of ether bonds and ester bonds in the second compound is at least two.

3. The carbon dioxide viscosifier according to claim 2, characterized in that: when the part connected to the amino group is a fluorinated polyacrylate group, the structure of the amino compound is shown in the following formula (I): Among them, R 1 is -H, -CH 3 , -CH 2 CH 3 , -CH 2 CH 2 CH 3 , -CH 2 OH, -C 2 H 4 OH, -C 3 H 6 OH, one of them; R 3 is a fluoroalkyl group of C 4 -C 12 , and the ratio of H to F in R 3 is (0 - 0.5):1; R 4 is -H or -CH 3 , R 5 is an alkylene group or a carbonyl group of C 1 -C 5 ; m:n = 1:(0.1 - 1), preferably m:n = 1:(0.1 - 0.3); when the part connected to the amino group is a fluorinated polyacrylate group, the number average molecular weight of the amino compound is 1000 - 10000, preferably 4000 - 7000.

4. The carbon dioxide viscosifier according to claim 2, characterized in that: when the part connected to the amino group is a polysiloxane group, the structure of the amino compound is shown in the following formula (II): Among them, R 1 is -H, -CH 3 , -CH 2 CH 3 , -CH 2 CH 2 CH 3 , -CH 2 OH, -C 2 H 4 OH, -C 3 H 6 OH; R 6 is an alkylene or ester group of C 1 -C 5 ; p:q = 1:(0.1 - 0.5), preferably p:q = 1:(0.1 - 0.3); when the part connected to the amino group is a polysiloxane group, the number-average molecular weight of the amino compound is 1000 - 20000, preferably 6000 - 10000.

5. The carbon dioxide viscosifier according to claim 2, characterized in that: when the part connected to the amino group is a long-chain hydrocarbon group, the structure of the amino compound is shown in the following formula (III): R 7 NHR 1 Formula (III); Among them, R 7 is an aliphatic hydrocarbon group of C 10 -C 24 , preferably an aliphatic hydrocarbon group of C 10 -C 20 ; R 1 is -H, -CH 3 , -CH 2 CH 3 , -CH 2 CH 2 CH 3 , -CH 2 OH, -C 2 H 4 OH, -C 3 H 6 OH, one of them.

6. The carbon dioxide viscosifier according to claim 2, characterized in that: when the part connected to the amino group is a fluorinated alkyl group, the structure of the amino compound is shown in the following formula (IV): R 8 NHR 1 Formula (IV); Among them, R 8 is a perfluorinated or partially fluorinated C 6 -C 24 alkyl group, preferably a perfluorinated or partially fluorinated C 6 -C 20 alkyl group, and the ratio of H to F in R 8 is less than or equal to 1:1; R 1 is -H, -CH 3 、-CH 2 CH 3 、-CH 2 CH 2 CH 3 、-CH 2 OH、-C 2 H 4 OH、-C 3 H 6 OH, one of them.

7. The carbon dioxide viscosifier according to claim 2, characterized in that: the ether bond-containing compound is at least one of the compounds shown in formula (V): and / or the ester bond-containing compound is at least one of the compounds shown in formula (VI): In the above formulas (V) and (VI), R 9 and R 10 are each independently an alkyl or aryl group of C 1 -C 6 ; R 9 and R 10 are each independently an alkyl or aryl group of C 1 -C 6 ; R 2 are each independently an alkylene group of C 1 -C 3 , a substituted alkylene group of C 1 -C 3 or -R 11 OR 12 -, where R 11 and R 12 are each independently an alkyl or aryl group of C 1 -C 6 ; preferably, the substituent in the substituted alkylene group of C 1 -C 3 is an alkyl or aryl group of C 1 -C 6 or an alkyl or aryl group-substituted ester group of C 1 -C 6 .

8. The carbon dioxide viscosifier according to any one of claims 1-7, characterized in that: the molar ratio of the amino compound to the second compound is 1:(0.5-10), preferably 1:(0.5-6).

9. A preparation method of a carbon dioxide viscosifier according to any one of claims 1-8, comprising the step of fully mixing components including the amino compound and the second compound.

10. A method for increasing the viscosity of carbon dioxide, comprising mixing a carbon dioxide viscosifier according to any one of claims 1-8 or a carbon dioxide viscosifier obtained by the preparation method according to claim 9 with carbon dioxide; preferably, the method comprises the step of alternately or jointly injecting the carbon dioxide viscosifier and carbon dioxide or first mixing the carbon dioxide viscosifier with carbon dioxide and then injecting it into a porous medium containing crude oil. More preferably, the carbon dioxide is supercritical and / or liquid carbon dioxide.

11. According to the method of claim 10, characterized in that: the hydrogen group in the amino compound and the oxygen group in the second compound associate in carbon dioxide to form an aggregate.

12. The method according to claim 10, characterized in that: the volume ratio of the carbon dioxide viscosifier to carbon dioxide is (0.1-5):100, preferably (0.3-3):

100.

13. Use of the carbon dioxide thickening agent according to any one of claims 1-8 or the carbon dioxide thickening agent obtained by the preparation method according to claim 9 in increasing the viscosity of carbon dioxide.

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