CO2-resistant lignin viscosity reducer as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of viscosity reduction in an oil reservoir development technology, and discloses a CO2-resistant lignin viscosity reducer and a preparation method and application thereof, and the CO2-resistant lignin viscosity reducer has a structure as shown in a formula (1). R is selected from H and at least one of a formula (2), R2 is alkylene of C1-C3, and R1, R3, R4 and R5 are the same or different and are respectively alkyl of C1-C18; the CO2-resistant lignin viscosity reducer can obviously reduce the viscosity of heavy oil; # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of viscosity reduction technology in reservoir development technology, and specifically relates to a CO2-resistant lignin viscosity reducer, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous growth of global energy demand, oil, as an important energy pillar, has become increasingly prominent in its extraction and utilization.

[0003] In the development process of heavy oil extraction technology, traditional thermal recovery technology once dominated. However, due to its high energy consumption, large environmental impact and other disadvantages, it has gradually become difficult to meet the current requirements of green extraction and sustainable development. Against this background, cold production technology has emerged. As a more economical, effective and environmentally friendly extraction method, cold production technology is gradually becoming a new trend in heavy oil extraction.

[0004] In the development process of cold production technology, CO2 has become a key element attracting much attention due to its unique properties. CO2 has the characteristics of strong diffusion and mass transfer ability and good miscibility with heavy oil. It can not only effectively reduce the viscosity of heavy oil, but also has the dual advantages of oil displacement and sequestration, showing great potential in heavy oil extraction. However, due to reasons such as large differences in the mobility of CO2, its viscosity reduction effect on heavy oil alone has certain limitations.

[0005] To make up for this deficiency, heavy oil cold production viscosity reduction technology has been continuously developed. The method of reducing the viscosity of heavy oil and increasing the fluidity of heavy oil by emulsification and other means has broad application prospects. At the same time, the CO2-assisted cold production viscosity reduction technology combines the effects of CO2 and viscosity reducers, realizing the synergistic effect of the two and effectively making up for the deficiencies of their respective viscosity reduction capabilities. Traditional cold production viscosity reducers have the characteristics of high viscosity reduction efficiency and strong activity. However, in a CO2 environment, the existing viscosity reducers have exposed a series of problems, such as poor structural stability, resulting in a significant reduction in the viscosity reduction effect in the presence of CO2 and being difficult to meet the requirements of actual extraction.

[0006] Therefore, there is an urgent need to study an efficient viscosity reduction system for CO2. Among many potential viscosity reducer materials, lignin-based functional monomers have shown good development potential. Lignin-based functional monomers carry aromatic olefin rings and polar functional groups. Through the formed hydrogen bonds and π-π stacking interactions, the interaction between asphaltene and resin can be effectively weakened, thereby significantly reducing the viscosity of heavy oil. However, although common lignin sulfonates have the characteristics of high temperature and high salt resistance, in an acidic environment, some structures are prone to oxidation reactions, which will seriously affect their viscosity reduction effect. During the process of CO2-assisted cold production, CO2 dissolves in water to form carbonic acid, making the system environment acidic. Therefore, the existing lignin sulfonates are difficult to meet the requirements of CO2 resistance.

[0007] To meet the development needs of heavy oil cold production technology, especially the application of CO2-assisted cold production viscosity reduction technology, it is urgent to develop a CO2-resistant lignin viscosity reducer. This viscosity reducer should not only have good viscosity reduction performance but also maintain a stable structure and excellent viscosity reduction effect in a CO2 environment, so as to provide strong support for the efficient exploitation of heavy oil resources in China. Based on this demand, the present invention is committed to providing a CO2-resistant lignin viscosity reducer with excellent performance, its preparation method and application to promote the further development of heavy oil exploitation technology. Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems existing in the existing heavy oil cold production viscosity reduction technology, such as poor structural stability, weakened viscosity reduction effect of the viscosity reducer under CO2-assisted cold production conditions, and the influence of common lignin sulfonates on the viscosity reduction effect due to easy oxidation in an acidic (CO2 environment). A CO2-resistant lignin viscosity reducer, its preparation method and application are provided. This CO2-resistant lignin viscosity reducer can significantly reduce the viscosity of heavy oil.

[0009] To achieve the above object, in the first aspect of the present invention, a CO2-resistant lignin viscosity reducer is provided, wherein the CO2-resistant lignin viscosity reducer has the structure shown in formula (1);

[0010]

[0011] wherein, R is selected from at least one of H and formula (2);

[0012]

[0013] R2 is an alkylene group with 1 - 3 carbon atoms;

[0014] R1, R3, R4 and R5 are the same or different, and each is an alkyl group with 1 - C 18 alkyl.

[0015] In the second aspect of the present invention, a preparation method of the aforementioned CO2-resistant lignin viscosity reducer is provided, wherein the preparation method includes:

[0016] (S1) In the presence of a catalyst and a solvent, the initial lignin-derived monomer shown in formula (3) and the bromoalkane monomer shown in formula (4) are contacted for reaction;

[0017]

[0018] (S2) The product obtained in step (S1) is removed of the solvent to obtain a crude product. The crude product is contacted with ethyl acetate to obtain a solution, and the solution is washed, separated, dried and concentrated to obtain the second lignin-based derivative monomer shown in formula (5);

[0019]

[0020] (S3) Epoxidize the second lignin-based derivative monomer shown in formula (5) to obtain a third lignin-based derivative monomer shown in formula (6) containing epoxy groups;

[0021]

[0022] (S4) Under acidic conditions, carry out a nucleophilic ring-opening reaction between the third lignin-based derivative monomer shown in formula (6) containing epoxy groups and N,N-dimethyl-1,3-propanediamine or N,N,N',N'-tetramethyldipropylenetriamine in a solvent to correspondingly obtain a fourth lignin-based derivative monomer shown in formula (7) or a fifth lignin-based derivative monomer shown in formula (8);

[0023]

[0024] (S5) Carry out a quaternization reaction between the fourth lignin-based derivative monomer shown in formula (7) or the fifth lignin-based derivative monomer shown in formula (8) and 1,3-propane sultone or 1,4-butane sultone in a solvent under a N2 atmosphere;

[0025] Among them, in formulas (3) to (8):

[0026] R2 is an alkylene group with 1 to 3 carbon atoms;

[0027] R1, R3, R4, and R5 are the same or different and are each an alkyl group with 1 to C 18 alkyl;

[0028] Obtain a CO2-resistant lignin viscosity reducer shown in formula (1).

[0029] The third aspect of the present invention provides an application of the aforementioned CO2-resistant lignin viscosity reducer in the process of CO2-assisted cold heavy oil production.

[0030] Through the above technical solutions, the beneficial effects of the present invention include:

[0031] (1) The CO2-resistant lignin viscosity reducer of the present invention combines a CO2-resistant zwitterionic group and a lignin-based functional group with high asphaltene-resin interfacial activity. During CO2-assisted cold heavy oil production, it can maintain a stable structure in a CO2 environment and will not cause a reduction in the viscosity reduction effect due to structural damage like traditional viscosity reducers.

[0032] (2) At the same time, compared with commonly used lignin sulfonates, the CO2-resistant lignin viscosity reducer of the present invention will not undergo an oxidation reaction to affect the viscosity reduction effect in an acidic CO2 environment. This viscosity reducer has good fluidity in its initial state, is convenient for injection, and can achieve efficient viscosity reduction. Description of the Drawings

[0033] Figure 1 It is a schematic diagram of the viscosity reduction of heavy oil by aqueous solutions with different concentrations containing the CO₂-resistant lignin viscosity reducer prepared in Example 1 of the present invention;

[0034] Figure 2 It is a schematic diagram of the viscosity reduction rate of heavy oil by aqueous solutions with different concentrations containing the CO₂-resistant lignin viscosity reducer prepared in Example 1 of the present invention;

[0035] Figure 3 It is an optical microscope image of the oil-in-water emulsion formed during the viscosity reduction of heavy oil by an aqueous solution with a concentration of 10 mg / mL of the CO₂-resistant lignin viscosity reducer prepared in Example 2 of the present invention. Detailed implementation manners

[0036] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0037] As described above, the first aspect of the present invention provides a CO₂-resistant lignin viscosity reducer, wherein the CO₂-resistant lignin viscosity reducer has the structure shown in formula (1);

[0038]

[0039] Wherein, R is selected from at least one of H and formula (2);

[0040]

[0041] R₂ is an alkylene group with 1 - 3 carbon atoms;

[0042] R₁, R₃, R₄ and R₅ are the same or different, and each is an alkyl group with 1 - C 18 alkyl.

[0043] According to the present invention, preferably, R₂ is an alkylene group with 1 - 2 carbon atoms.

[0044] According to the present invention, preferably, R₁, R₃, R₄ and R₅ are the same or different, and each is an alkyl group with 1 - C 15 alkyl.

[0045] The inventors of the present invention have found that: by using the specific CO2-resistant lignin viscosity reducer of the present invention, the aromatic olefin ring (benzene ring) and polar functional groups (oxygen-containing group hydroxyl (-OH), ether bond (-O-), and sulfonic acid group (-SO3H)) carried by the lignin-based functional monomers are utilized to effectively weaken the asphaltene-colloid interaction in heavy oil through the formed hydrogen bonds and π-π stacking interactions, and significantly reduce the viscosity of heavy oil. It has a stable structure in a CO2 environment and will not cause a reduction in the viscosity reduction effect due to structural damage like traditional viscosity reducers. At the same time, compared with commonly used lignin sulfonates, the CO2-resistant lignin viscosity reducer of the present invention will not undergo an oxidation reaction to affect the viscosity reduction effect in an acidic CO2 environment. This viscosity reducer has good fluidity in its initial state, is easy to inject, can achieve efficient viscosity reduction, effectively overcomes the defect of weak viscosity reduction ability of existing viscosity reducers in a CO2 environment, provides an excellent, stable and reliable viscosity reduction solution for CO2-assisted cold production of heavy oil, and can promote the efficient exploitation of heavy oil resources.

[0046] The second aspect of the present invention provides a preparation method of the aforementioned CO2-resistant lignin viscosity reducer, wherein the preparation method includes:

[0047] (S1) In the presence of a catalyst and a solvent, the initial lignin-derived monomer shown in formula (3) and the bromoalkane monomer shown in formula (4) are contacted for reaction;

[0048]

[0049] (S2) The solvent is removed from the product obtained in step (S1) to obtain a crude product. The crude product is contacted with ethyl acetate to obtain a solution, and the solution is washed, separated, dried, and concentrated to obtain the second lignin-based derivative monomer shown in formula (5);

[0050]

[0051] (S3) The second lignin-based derivative monomer shown in formula (5) is subjected to an epoxidation reaction to obtain a third lignin-based derivative monomer shown in formula (6) containing an epoxy group;

[0052]

[0053] (S4) Under acidic conditions, the third lignin-based derivative monomer shown in formula (6) containing an epoxy group and N,N-dimethyl-1,3-propanediamine or N,N,N',N'-tetramethyldipropylenetriamine are subjected to a nucleophilic ring-opening reaction in a solvent to respectively obtain a fourth lignin-based derivative monomer shown in formula (7) or a fifth lignin-based derivative monomer shown in formula (8);

[0054]

[0055] (S5) Quaternize the fourth lignin-based derivative monomer shown in formula (7) or the fifth lignin-based derivative monomer shown in formula (8) with 1,3-propane sultone or 1,4-butane sultone in a solvent under a nitrogen atmosphere;

[0056] Wherein, in formulas (3) to (8):

[0057] R2 is an alkylene group with 1 to 3 carbon atoms;

[0058] R1, R3, R4 and R5 are the same or different, and each is an alkyl group with 1 to C 18 alkyl;

[0059] Obtain the CO2-resistant lignin viscosity reducer shown in formula (1).

[0060] The inventors of the present invention found that: the viscosity reducer of the present invention combines a CO2 zwitterionic group with a lignin-based functional group having high asphaltene-resin interfacial activity. During CO2-assisted cold production of heavy oil, it can maintain a stable structure in a CO2 environment and will not cause a reduction in viscosity reduction effect due to structural damage like traditional viscosity reducers. At the same time, compared with commonly used lignin sulfonates, the CO2-resistant lignin viscosity reducer of the present invention will not undergo an oxidation reaction to affect the viscosity reduction effect in an acidic CO2 environment. This viscosity reducer has good fluidity in its initial state, is convenient for injection, and can achieve efficient viscosity reduction.

[0061] According to the present invention, in step (S1), the catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, and potassium carbonate, and preferably potassium carbonate.

[0062] According to the present invention, the solvent is at least one of dimethylformamide, dimethyl sulfoxide, and acetonitrile, and preferably acetonitrile.

[0063] According to the present invention, in step (S1), the reaction conditions include: the temperature is 80 - 100 °C, and the time is 6 - 10 h; preferably, the temperature is 85 - 90 °C, and the time is 7 - 8 h.

[0064] According to the present invention, in step (S2), the product obtained in step (S1) is depressurized to remove the solvent under a pressure of 0.1 - 100 Pa, ethyl acetate is added to dissolve the crude product, and then saturated NaCl solution is added for washing, liquid separation, anhydrous magnesium sulfate is added for drying. After filtration, the filtrate is concentrated to dryness to obtain the second lignin-based derivative monomer shown in formula (5); wherein, drying is carried out using a drying agent, and the drying agent is selected from at least one of anhydrous sodium sulfate, anhydrous potassium carbonate, and anhydrous magnesium sulfate, and preferably anhydrous magnesium sulfate.

[0065] According to the present invention, in step (S3), the epoxidation reaction is a peroxyacid epoxidation reaction and / or a base-catalyzed epoxidation reaction, preferably a base-catalyzed epoxidation reaction.

[0066] According to the present invention, preferably, the conditions for the peroxyacid epoxidation reaction include: reacting in the presence of a peroxyacid and a solvent at a temperature of 20 - 50 °C for a time of 4 - 24 h; more preferably, the peroxyacid is m-chloroperoxybenzoic acid and / or peracetic acid, and the solvent is dichloromethane;

[0067] According to the present invention, preferably, the conditions for the base-catalyzed epoxidation reaction include: reacting in the presence of a hydrogen peroxide catalyst at a temperature of 40 - 60 °C for a time of 6 - 10 h, using water as the solvent.

[0068] According to the present invention, in step (S4), under acidic conditions, the third lignin-based derivative monomer shown in formula (6) containing an epoxy group is subjected to a nucleophilic ring-opening reaction with N,N-dimethyl-1,3-propanediamine or N,N,N',N'-tetramethyldipropylenetriamine in a solvent, where the solvent is selected from at least one of water, methanol, ethanol, and N,N-dimethylformamide, preferably water.

[0069] In the present invention, the structural formula of N,N-dimethyl-1,3-propanediamine is:

[0070]

[0071] In the present invention, the molecular formula of N,N,N',N'-tetramethyldipropylenetriamine is C 10 H 25 N3, and the structural formula is:

[0072] According to the present invention, in step (S4), the acidic condition is adding 0.5 wt% acetic acid.

[0073] According to the present invention, the conditions for the nucleophilic ring-opening reaction include: reacting in the presence of 0.5 wt% acetic acid at a temperature of 50 - 60 °C for a time of 12 - 24 h.

[0074] According to the present invention, in step (S5), the solvent is acetone.

[0075] According to the present invention, in step (S5), it is quaternized with 1,3-propane sultone and 1,4-butane sultone in a solvent under an N2 atmosphere, preferably 1,3-propane sultone, and the structural formula is:

[0076] According to the present invention, the conditions for the quaternization reaction include: reacting under the conditions of a temperature of 20 - 80 °C and a time of 5 - 24 h.

[0077] The third aspect of the present invention provides an application of the foregoing CO2-resistant lignin viscosity reducer in the process of CO2-assisted cold production of heavy oil.

[0078] According to the present invention, the CO2-resistant lignin viscosity reducer is formulated into an aqueous solution with a concentration of 0.1 - 10 mg / mL; preferably, the viscosity of the CO2-resistant lignin viscosity reducer solution with a concentration of 10 mg / mL is 8 - 30 mPa·s, preferably 8 - 20 mPa·s, and more preferably 8 - 12 mPa·s.

[0079] According to the present invention, the viscosity reduction rate of the heavy oil by the CO2-resistant lignin viscosity reducer solution with a concentration of 0.1 - 10 mg / mL can reach more than 21%, preferably the viscosity reduction rate of the heavy oil by the CO2-resistant lignin viscosity reducer solution with a concentration of 1 mg / mL can reach more than 82%, and more preferably the viscosity reduction rate of the heavy oil by the CO2-resistant lignin viscosity reducer solution with a concentration of 3 mg / mL can reach more than 95%.

[0080] The present invention will be described in detail below through examples.

[0081] In the following examples and comparative examples:

[0082] The viscosity reduction rate of the petroleum is measured according to the method of GB / T 1.1-2009;

[0083] The heavy oil is kept at a constant temperature of 50 °C in a constant temperature water bath for 1 h, stirred to remove the free water and bubbles therein, and its viscosity μ0 at 50 °C is measured with a viscometer within 20 s.

[0084] Weigh 280 g of the heavy oil sample into a beaker, add 120 g of the prepared CO2-resistant lignin viscosity reducer sample solution, place it in a constant temperature water bath at 50 °C, keep it at a constant temperature for 1 h, place the stirring paddle at the center of the beaker and 2 - 3 mm above the bottom, adjust the rotation speed to 250 revolutions per minute, and stir for 2 min under the condition of constant temperature. The viscosity μ of the prepared heavy oil emulsion is quickly measured with a rotary viscometer within 20 s.

[0085] Calculation of the viscosity reduction rate of the heavy oil:

[0086] Among them:

[0087] f is the viscosity reduction rate;

[0088] μ0 is the viscosity of the heavy oil sample at 50 °C, with the unit of mPa·s;

[0089] μ is the viscosity of the heavy oil emulsion after adding the sample solution, with the unit of mPa·s.

[0090] The viscosity parameters were measured by rheometer.

[0091] Example 1

[0092] This example is to illustrate the preparation of a CO2 resistant lignin viscosity reducer using the method of the present invention.

[0093] (S1) In a beaker containing 100 mL of acetonitrile, 1.64 g (10 mmol) of the initial lignin-derived monomer represented by the structure of formula (a) and 3.16 g of tridecane bromide (12 mmol) were added, and 0.046 g of potassium carbonate (1 wt%) was added, and the mixture was stirred at 25° C. for 8 h.

[0094]

[0095] (S2) removing the solvent from the product obtained in step (S1) under a pressure of 80 Pa, adding ethyl acetate to dissolve the crude product, then adding a saturated NaCl solution to wash, separating the liquids, adding anhydrous magnesium sulfate to dry, filtering, and concentrating the filtrate to dryness to obtain a second lignin-based derivative monomer represented by formula (b);

[0096]

[0097] (S3) 3.46 g (10 mmol) of the second lignin-based derivative monomer of formula (b) containing a double bond obtained in step (S2) was added to 100 mL of an aqueous solution containing 17.5% hydrogen peroxide, and the mixture was stirred at 25° C. for 12 h, and the pH of the reaction system was adjusted to neutral with dilute hydrochloric acid to terminate the reaction. Ethyl acetate was added to extract the product, and the phases were separated. Anhydrous magnesium sulfate was added to the organic phase for drying, and the phase was filtered. The filtrate was concentrated and dried to obtain a third lignin-based derivative monomer of formula (c) containing an epoxy group;

[0098]

[0099] (S4) In 100 mL of methanol at a pH of 5, 3.72 g (10 mmol) of the third lignin-based derivative monomer of formula (c) obtained in step (S3) and 1.22 g (12 mmol) of N,N-dimethyl-1,3-propylenediamine monomer were added, and the mixture was stirred and reacted at 25° C. for 16 h to obtain a fourth lignin-based derivative monomer of formula (d);

[0100]

[0101] (S5) Add 4.44 g (10 mmol) of the fourth lignin-based derivative monomer shown in formula (d) obtained in step (S4) and 1.46 g (12 mmol) of 1,3-propane sultone to 50 mL of acetone, introduce N2, stir and react at 25 °C for 5 h, remove part of the solvent under reduced pressure, add ether to precipitate the product, filter, and vacuum dry the solid product to obtain the CO2-resistant lignin viscosity reducer shown in formula (e);

[0102]

[0103] In addition, Figure 1 Figure showing the viscosity reduction of heavy oil by aqueous solutions with different concentrations containing the CO2-resistant lignin viscosity reducer prepared in Example 1 of the present invention. From Figure 1 It can be seen that: as the sample concentration increases, the viscosity reduction effect on heavy oil is better. When the sample concentration is 10 mg / mL, the viscosity of heavy oil can be reduced to 671 mPa·s.

[0104] Figure 2 Figure showing the viscosity reduction rate of heavy oil by aqueous solutions with different concentrations containing the CO2-resistant lignin viscosity reducer prepared in Example 1 of the present invention. From Figure 2 It can be seen that: as the sample concentration increases, the viscosity reduction rate of heavy oil is higher. When the sample concentration is 5 mg / mL, the viscosity reduction rate of heavy oil can reach more than 98%.

[0105] Example 2

[0106] This example is to illustrate the CO2-resistant lignin viscosity reducer prepared by the method of the present invention.

[0107] Prepare the CO2-resistant lignin viscosity reducer according to the same method as in Example 1. Specifically:

[0108] (S1) to (S3) are the same as in Example 1.

[0109] (S4) In 100 mL of methanol with a pH of 5, add 3.72 g (10 mmol) of the third lignin-based derivative monomer containing epoxy shown in formula (c) obtained in step (S3) and 2.24 g (12 mmol) of N,N,N',N'-tetramethyldipropylenetriamine monomer, stir and react at 25 °C for 16 h to obtain the fourth lignin-based derivative monomer shown in formula (f);

[0110]

[0111] (S5) Add 5.29 g (10 mmol) of the fourth lignin-based derivative monomer shown in formula (f) obtained in step (S4) and 2.68 g (22 mmol) of 1,3-propane sultone to 50 mL of acetone, introduce N2, stir and react at 25 °C for 5 h, remove part of the solvent under reduced pressure, add ether to precipitate the product, filter, and vacuum dry the solid product to obtain the CO2-resistant lignin viscosity reducer shown in formula (g);

[0112]

[0113] In addition, Figure 3 Figure for the water-in-oil emulsion formed when reducing the viscosity of heavy oil with an aqueous solution containing the CO2-resistant lignin viscosity reducer prepared in Example 2 of the present invention at a concentration of 10 mg / mL. From Figure 3 It can be seen that: This CO2-resistant lignin viscosity reducer can emulsify heavy oil into a water-in-oil emulsion, thereby achieving the viscosity reduction effect.

[0114] Example 3

[0115] This example is to illustrate the CO2-resistant lignin viscosity reducer prepared by the method of the present invention.

[0116] Prepare the CO2-resistant lignin viscosity reducer according to the same method as in Example 1. Specifically:

[0117] (S1) to (S4) are the same as in Example 2.

[0118] (S5) Add 5.29 g (10 mmol) of the fourth lignin-based derivative monomer shown in formula (f) obtained in step (S4) and 2.99 g (22 mmol) of 1,4-butane sultone to 50 mL of acetonitrile, introduce N2, stir and react at 30 °C for 12 h, remove part of the solvent under reduced pressure, add ether to precipitate the product, filter, and vacuum dry the solid product to obtain the CO2-resistant lignin viscosity reducer shown in formula (h);

[0119]

[0120] Example 4

[0121] This example is to illustrate the preparation of the CO2-resistant lignin viscosity reducer by the method of the present invention.

[0122] (S1) Add 2.28 g (10 mmol) of the initial lignin derivative monomer shown in the structure of formula (i) and 4.00 g of octadecyl bromide (12 mmol) to a beaker containing 100 mL of acetonitrile, add 0.037 g of potassium hydroxide (0.6 wt%), and stir and react at 25 °C for 12 h.

[0123]

[0124] (S2) The product obtained in step (S1) is depressurized to remove the solvent under a pressure of 50 Pa. Ethyl acetate is added to dissolve the crude product, and then saturated NaCl solution is added for washing, liquid separation, and anhydrous magnesium sulfate is added for drying. After filtration, the filtrate is concentrated to dryness to obtain the second lignin-based derivative monomer shown in formula (j).

[0125]

[0126] (S3) 4.94 g (10 mmol) of the second lignin-based derivative monomer containing a double bond shown in formula (j) obtained in step (S2) is added to 100 mL of an aqueous solution containing 17.5% hydrogen peroxide. The mixture is stirred and reacted at 25 °C for 8 h, and the pH of the reaction system is adjusted to neutral with dilute hydrochloric acid to terminate the reaction. Ethyl acetate is added to extract the product, and after liquid separation, anhydrous magnesium sulfate is added to dry the organic phase. After filtration, the filtrate is concentrated and dried to obtain the third lignin-based derivative monomer containing an epoxy group shown in formula (k).

[0127]

[0128] (S4) In 100 mL of methanol with a pH of 5, 5.20 g (10 mmol) of the third lignin-based derivative monomer containing an epoxy group shown in formula (k) obtained in step (S3) and 1.22 g (12 mmol) of N,N-dimethyl-1,3-propanediamine monomer are added. The mixture is stirred and reacted at 25 °C for 12 h to obtain the fourth lignin-based derivative monomer shown in formula (l).

[0129]

[0130] (S5) 6.03 g (10 mmol) of the fourth lignin-based derivative monomer shown in formula (l) obtained in step (S4) and 1.46 g (12 mmol) of 1,3-propane sultone are added to 50 mL of acetone. N2 is introduced, and the mixture is stirred and reacted at 25 °C for 5 h. Part of the solvent is removed under reduced pressure, and ether is added to precipitate the product. After filtration, the solid product is dried in vacuo to obtain the CO2-resistant lignin viscosity reducer shown in formula (n).

[0131]

[0132] Example 5

[0133] This example is to illustrate the CO2-resistant lignin viscosity reducer prepared by the method of the present invention.

[0134] The CO2-resistant lignin viscosity reducer is prepared according to the same method as in Example 4. Specifically:

[0135] (S1) to (S3) are the same as in Example 4.

[0136] (S4) In 100 mL of methanol with a pH of 5, 5.20 g (10 mmol) of the third lignin-based derivative monomer containing epoxy obtained in step (S3) and 2.24 g (12 mmol) of N,N,N',N'-tetramethyldiallyl triamine monomer were added, and the mixture was stirred and reacted at 25 °C for 18 h to obtain the fourth lignin-based derivative monomer shown in formula (o);

[0137]

[0138] (S5) 6.88 g (10 mmol) of the fourth lignin-based derivative monomer shown in formula (o) obtained in step (S4) and 2.68 g (22 mmol) of 1,3-propane sultone were added to 50 mL of acetone, N2 was introduced, the mixture was stirred and reacted at 25 °C for 5 h, part of the solvent was removed under reduced pressure, ether was added to precipitate the product, and after filtration, the solid product was dried in vacuo to obtain the CO2-resistant lignin viscosity reducer shown in formula (p);

[0139]

[0140] Example 6

[0141] (S1) to (S4) were the same as in Example 5.

[0142] (S5) 6.88 g (10 mmol) of the fourth lignin-based derivative monomer shown in formula (o) obtained in step (S4) and 2.99 g (22 mmol) of 1,4-butane sultone were added to 50 mL of acetonitrile, N2 was introduced, the mixture was stirred and reacted at 30 °C for 15 h, part of the solvent was removed under reduced pressure, ether was added to precipitate the product, and after filtration, the solid product was dried in vacuo to obtain the CO2-resistant lignin viscosity reducer shown in formula (q);

[0143]

[0144] Comparative Example 1

[0145] Sodium lignosulfonate was used, and the structure of the sodium lignosulfonate was:

[0146]

[0147] Comparative Example 2

[0148] The CO2-resistant lignin viscosity reducer was prepared in the same method as in Example 1. Specifically:

[0149] (S1) to (S3) were the same as in Example 1.

[0150] (S4) In 100 mL of methanol with a pH of 5, add 3.72 g (10 mmol) of the third lignin-based derivative monomer containing epoxy shown in formula (c) obtained in step (S3) and 1.93 g (12 mmol) of 3-aminopropanesulfonate monomer, and stir and react at 40 °C for 12 h to obtain the lignin viscosity reducer shown in formula (r);

[0151]

[0152] Comparative Example 3

[0153] Prepare the CO2-resistant lignin viscosity reducer according to the same method as in Example 1. Specifically:

[0154] (S1) to (S3) are the same as in Example 1.

[0155] (S4) In 100 mL of methanol with a pH of 5, add 3.72 g (10 mmol) of the third lignin-based derivative monomer containing epoxy shown in formula (c) obtained in step (S3) and 3.10 g (12 mmol) of the monomer of formula (s), and stir and react at 40 °C for 12 h to obtain the lignin viscosity reducer shown in formula (t);

[0156]

[0157] Application Example 1

[0158] Mix the lignin viscosity reducers prepared in Examples 1-3 and Comparative Examples 1-3 with different concentrations with heavy oil, and test their viscosity reduction effects on heavy oil. The test results are shown in Table 1 (viscosity of heavy oil after viscosity reduction) and Table 2 (viscosity reduction rate):

[0159] Table 1

[0160]

[0161] Table 2

[0162]

[0163]

[0164] It can be seen from the above results that the CO2-resistant lignin viscosity reducer of the present invention can achieve efficient viscosity reduction of heavy oil. The viscosity reduction rate of the CO2-resistant lignin viscosity reducer at 3 mg / mL for heavy oil can reach more than 95%.

[0165] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including the combination of each technical feature in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A CO2-resistant lignin viscosity reducer, characterized in that, The CO₂-resistant lignin viscosity reducer has the structure shown in formula (1); wherein, R is selected from at least one of H and formula (2); R₂ is an alkylene group with 1 - 3 carbon atoms; R1, R3, R4 and R5 are the same or different and each is an alkyl group having 1 to 18 carbons.

2. The CO₂-resistant lignin viscosity reducer according to claim 1, wherein R₂ is an alkylene group with 1 - 2 carbon atoms; R1, R3, R4, and R5 are the same or different and each is an alkyl group having C1-C 15 alkyl group.

3. A preparation method of the CO2-resistant lignin viscosity reducer according to claim 1 or 2, characterized in that, The preparation method comprises: (S1) In the presence of a catalyst and a solvent, contacting the initial lignin-derived monomer shown in formula (3) with the bromoalkane monomer shown in formula (4) for reaction; (S2) Removing the solvent from the product obtained in step (S1) to obtain a crude product, contacting the crude product with ethyl acetate to obtain a solution, and subjecting the solution to washing, liquid separation, drying, and concentration treatments to obtain the second lignin-based derivative monomer shown in formula (5); (S3) Epoxidizing the second lignin-based derivative monomer shown in formula (5) to obtain the third lignin-based derivative monomer shown in formula (6) containing an epoxy group; (S4) Under acidic conditions, subjecting the third lignin-based derivative monomer shown in formula (6) containing an epoxy group to a nucleophilic ring-opening reaction with N,N-dimethyl-1,3-propanediamine or N,N,N',N'-tetramethyldipropylenetriamine in a solvent to correspondingly obtain the fourth lignin-based derivative monomer shown in formula (7) or the fifth lignin-based derivative monomer shown in formula (8); (S5) Subjecting the fourth lignin-based derivative monomer shown in formula (7) or the fifth lignin-based derivative monomer shown in formula (8) to a quaternization reaction with 1,3-propane sultone or 1,4-butane sultone in a solvent under a N₂ atmosphere; wherein, in formulas (3) to (8): R₂ is an alkylene group with 1 - 3 carbon atoms; R1, R3, R4 and R5 are the same or different and each is an alkyl group having 1 to 18 carbon atoms; to obtain the CO₂-resistant lignin viscosity reducer shown in formula (1).

4. The preparation method according to claim 3, wherein, In step (S1), the catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, and potassium carbonate; and / or, the solvent is at least one of dimethylformamide, dimethyl sulfoxide, and acetonitrile.

5. The preparation method according to claim 3, wherein, In step (S2), drying is carried out using a desiccant, and the desiccant is selected from at least one of anhydrous sodium sulfate, anhydrous potassium carbonate, and anhydrous magnesium sulfate.

6. The preparation method according to claim 3, wherein In step (S3), the epoxidation reaction is a peroxyacid epoxidation reaction and / or a base-catalyzed epoxidation reaction; Preferably, the conditions for the peroxyacid epoxidation reaction include: reacting in the presence of a peroxyacid and a solvent at a temperature of 20 - 50 °C for 4 - 24 h; more preferably, the peroxyacid is m-chloroperoxybenzoic acid and / or peracetic acid, and the solvent is dichloromethane; Preferably, the conditions for the base-catalyzed epoxidation reaction include: reacting in the presence of a hydrogen peroxide catalyst at a temperature of 40 - 60 °C for 6 - 10 h.

7. The preparation method according to claim 3, wherein In step (S4), the solvent is selected from at least one of water, methanol, ethanol, and N,N-dimethylformamide; and / or, the conditions for the nucleophilic ring-opening reaction include: reacting in the presence of an acetic acid catalyst at a temperature of 50 - 60 °C for 12 - 24 h.

8. The preparation method according to claim 3, wherein, In step (S5), the solvent is selected from one of acetonitrile and acetone; And / or, the conditions for the quaternization reaction include: reacting under the conditions of a temperature of 20-80°C and a time of 5-24 h.

9. Application of the CO2-resistant lignin viscosity reducer according to claim 1 or 2 in the process of CO2-assisted cold production of heavy oil.

10. The application according to claim 9, wherein, The CO2-resistant lignin viscosity reducer is formulated into an aqueous solution with a concentration of 0.5-2 wt%.

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