Composition for preparing a flooding agent and flooding agent, process for preparing the same and use thereof

Abstract

The present application relates to the technical field of oil field, in particular to a kind of preparation oil displacement agent composition and oil displacement agent and its preparation method and application, the composition includes main agent, synergist and stabilizer, wherein, the main agent includes by the raw material copolymerization of containing acrylamide, acryloyl morpholine and ethylene pyrrolidone obtained ternary copolymer A;And / or by the raw material copolymerization of containing acrylamide, acryloyl morpholine and 2-acrylamido-2-methylpropane sulfonic acid obtained ternary copolymer B.The composition of the present application has high system phase transition temperature, viscosity and stability under high temperature.

Description

Technical Field

[0001] This invention relates to the field of oilfield technology, specifically to a composition for preparing an oil displacement agent, the oil displacement agent itself, its preparation method, and its application. Background Technology

[0002] Polymer enhanced oil recovery (EOR) is an important technology that utilizes the high viscosity of polymers to improve the oil-water mobility ratio and thus increase the sweep efficiency. Polyacrylamide is currently the most widely used and consumed polymer in major oilfields. As oil and gas exploration and development gradually expands into deeper and ultra-deep reservoirs, high-temperature deep wells are becoming increasingly common. For example, carbonate reservoirs in Sinopec's Northwest Oilfield are generally deep and hot (often exceeding 130°C). However, ordinary polyacrylamide has poor temperature resistance (generally below 100°C), and its viscosity drops sharply with increasing temperature, resulting in a high oil-water mobility ratio. This leads to low EOR efficiency of polymers at high temperatures, failing to meet the requirements for efficient development of high-temperature deep well oil and gas reservoirs.

[0003] We found that literature reports on heat-resistant polymers for oil displacement mainly focus on the modification of acrylamide polymers. The main methods employed are rigidification of the polymer molecular side chains and functionalization design of functional groups. This involves introducing functional groups such as larger-volume groups (benzene rings, long-chain alkyl groups, etc.), hydrolysis-resistant groups (pyrrolidone rings, sulfonic acid groups, etc.), and hydrophobic groups (long-chain alkyl groups) into the side chains. Through steric hindrance, synergistic effects, or strong non-covalent interactions between functional groups (hydrogen bonds, electrostatic forces, van der Waals forces, hydrophobic association forces), the mobility of the polymer backbone is restricted, thereby improving its heat resistance. While these measures can indeed improve the heat resistance of polymers to some extent, the phase transition temperature remains low, and the problem of high-temperature viscosity reduction remains unresolved.

[0004] CN103396284A discloses a hydrophobic monomer for the synthesis of a temperature-sensitive polymer oil displacement agent and its preparation method. The oil displacement agent is copolymerized from N-alkylacrylamide, acrylamide and a temperature-resistant and salt-resistant hydrophobic monomer. However, the phase transition temperature of this oil displacement agent is low (50℃), and there is a problem of a sharp drop in viscosity at high temperatures. CN103214631A discloses a temperature-sensitive modified silica nanosphere and its preparation method and application. This material can be used to improve oil recovery. However, the phase transition temperature of this material is low (32-33℃), and it is not suitable for high-temperature environments of 130℃.

[0005] Therefore, it is still necessary to develop a high-temperature heat-sensitive oil displacement agent with high phase transformation temperature, high viscosity at high temperature (130℃), and good oil displacement efficiency to improve crude oil recovery. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of poor temperature resistance (generally below 100℃) of existing oil displacement agents, the sharp drop in viscosity at increasing temperature, and the large oil-water mobility ratio, which leads to low oil displacement efficiency at high temperatures and cannot meet the needs of efficient development of high-temperature deep well oilfields. This invention provides a composition for preparing an oil displacement agent, the oil displacement agent itself, its preparation method, and its application. The oil displacement agent prepared by this composition has the advantages of high phase transition temperature and high viscosity at 130℃. It can effectively utilize the high viscosity of polymers to improve the oil-water mobility ratio and thus improve the sweep efficiency, ultimately significantly increasing the recovery rate.

[0007] To achieve the above objectives, a first aspect of the present invention provides a composition for preparing an oil displacement agent, the composition comprising a main agent, a synergist, and a stabilizer, wherein the main agent comprises a terpolymer A obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine, and vinylpyrrolidone; and / or a terpolymer B obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine, and 2-acrylamido-2-methylpropanesulfonic acid.

[0008] Preferably, the main agent is a mixture of terpolymer A and terpolymer B, and more preferably, the mass ratio of terpolymer A to terpolymer B is 1-9:1.

[0009] Preferably, the relative molecular mass of the terpolymer A is 2.30 × 10⁻⁶. 6 -4.50×10 6 .

[0010] Preferably, the relative molecular mass of the terpolymer B is 2.30 × 10⁻⁶. 6 -4.50×10 6 .

[0011] Preferably, in the raw materials of the terpolymer A, the content of acrylamide is 40-70 wt%, the content of acryloylmorpholine is 20-30 wt%, and the content of vinylpyrrolidone is 10-30 wt%, based on 100% by mass.

[0012] Preferably, in the raw materials of the terpolymer B, the content of acrylamide is 40-70 wt%, the content of acryloylmorpholine is 20-30 wt%, and the content of 2-acrylamido-2-methylpropanesulfonic acid is 10-30 wt% by mass.

[0013] Preferably, the synergist includes at least one of boron nitride, positively charged gel, and graphene.

[0014] Preferably, the stabilizer includes at least one of sodium sulfite, thiourea, and sodium thiosulfate.

[0015] Preferably, the composition comprises, in 100 parts by weight: 0.2-2.0 parts by weight of the main agent, 0.01-3.0 parts by weight of the synergist, 0.05-2.0 parts by weight of the stabilizer, and the balance being water.

[0016] Preferably, the composition comprises, in 100 parts by weight: 0.5-1.25 parts by weight of the main agent, 0.05-1.0 parts by weight of the synergist, 0.2-0.8 parts by weight of the stabilizer, and the balance being water.

[0017] A second aspect of the present invention provides an oil displacement agent prepared by processing the composition of the present invention.

[0018] A third aspect of the present invention provides a method for preparing the oil displacement agent of the present invention, the method comprising:

[0019] a. Dissolve the synergist and stabilizer in water to obtain the first solution;

[0020] b. Dissolve the main agent in water to obtain a second solution;

[0021] c. Mix the first solution and the second solution to obtain the oil displacement agent.

[0022] The fourth aspect of this invention provides the application of the oil displacement agent described herein in polymer flooding oil recovery from core samples.

[0023] Compared with the prior art, the advantages of this invention are:

[0024] This invention provides a composition for preparing an oil displacement agent. The main component of the composition comprises a terpolymer A obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine, and vinylpyrrolidone, and / or a terpolymer B obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine, and 2-acrylamido-2-methylpropanesulfonic acid. The copolymer obtained by polymerization ensures that the main component is soluble in water, improves the phase transition temperature and thermal stability of the main component at high temperatures, and the synergist can organically combine the rigidity and thermal stability of nanoparticles with the thermosensitive association characteristics of the terpolymer of this invention, significantly improving the phase transition temperature and viscosity of the system at high temperatures. The stabilizer can reduce the reduction in the hydrodynamic radius of the terpolymer of this invention, thereby inhibiting the oxidative degradation of the copolymer under high temperature conditions.

[0025] The oil displacement agent prepared by the composition of the present invention has the advantages of high phase transformation temperature and high viscosity at 130°C, which can significantly improve the crude oil recovery rate. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] The first aspect of the present invention provides a composition for preparing an oil displacement agent, the composition comprising a main agent, a synergist and a stabilizer, wherein the main agent comprises a terpolymer A obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine and vinylpyrrolidone; and / or a terpolymer B obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine and 2-acrylamido-2-methylpropanesulfonic acid.

[0028] The main component of this composition comprises a terpolymer A obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine and vinylpyrrolidone, and / or a terpolymer B obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine and 2-acrylamido-2-methylpropanesulfonic acid. The copolymer obtained by polymerization ensures that the main component is soluble in water, improves the phase transition temperature and thermal stability of the main component at high temperatures. The synergist can organically combine the rigidity and thermal stability of nanoparticles with the thermosensitive association characteristics of the terpolymer of this invention, significantly improving the phase transition temperature and viscosity of the system at high temperatures. The stabilizer can reduce the reduction in the hydrodynamic radius of the terpolymer of this invention, thereby inhibiting the oxidative degradation of the copolymer under high temperature conditions.

[0029] According to a preferred embodiment of the present invention, the main agent is a mixture of terpolymer A and terpolymer B, preferably with a mass ratio of terpolymer A to terpolymer B of 1-9:1. By adopting the aforementioned preferred embodiment, the phase transition temperature and viscosity and stability at high temperatures of the system can be further improved.

[0030] According to a preferred embodiment of the present invention, the relative molecular mass of the terpolymer A is 2.30 × 10⁻⁶. 6 -4.50×10 6 By adopting the aforementioned preferred methods, the phase transition temperature, viscosity at high temperatures, and stability of the system can be further improved.

[0031] According to a preferred embodiment of the present invention, the relative molecular mass of the terpolymer B is 2.30 × 10⁻⁶. 6 -4.50×10 6 By adopting the aforementioned preferred methods, the phase transition temperature, viscosity at high temperatures, and stability of the system can be further improved.

[0032] According to a preferred embodiment of the present invention, the raw materials of the terpolymer A, by mass percentage, contain 40-70 wt% acrylamide, 20-30 wt% acryloylmorpholine, and 10-30 wt% vinylpyrrolidone. By adopting the aforementioned preferred embodiment, the phase transition temperature and viscosity and stability at high temperatures of the system can be further improved.

[0033] According to a preferred embodiment of the present invention, in the raw materials of the terpolymer B, the content of acrylamide is 40-70 wt%, the content of acryloylmorpholine is 20-30 wt%, and the content of 2-acrylamido-2-methylpropanesulfonic acid is 10-30 wt%, based on 100% by mass. By adopting the aforementioned preferred embodiment, the phase transition temperature and viscosity and stability at high temperatures of the system can be further improved.

[0034] In this invention, a wide range of synergists can be selected. According to a preferred embodiment of the invention, the synergist includes at least one of boron nitride, positively charged adhesive, and graphene. By adopting the aforementioned preferred embodiment, the phase transition temperature and viscosity and stability at high temperatures of the system can be further improved.

[0035] In this invention, a wide range of stabilizers can be selected. According to a preferred embodiment of the invention, the stabilizer includes at least one of sodium sulfite, thiourea, and sodium thiosulfate. By employing the aforementioned preferred method, the phase transition temperature and viscosity and stability at high temperatures of the system can be further improved.

[0036] According to a preferred embodiment of the present invention, the oil displacement agent comprises, per 100 parts by weight: 0.2-2.0 parts by weight of the main agent, 0.01-3.0 parts by weight of the synergist, 0.05-2.0 parts by weight of the stabilizer, and the balance being water. By adopting the aforementioned preferred embodiment, the phase transition temperature and viscosity and stability at high temperatures of the system can be further improved.

[0037] According to a preferred embodiment of the present invention, the composition comprises, by weight, 0.5-1.25 parts of a main agent, 0.05-1.0 parts of a synergist, and 0.2-0.8 parts of a stabilizer, with the balance being water. By adopting the aforementioned preferred embodiment, the phase transition temperature and viscosity and stability at high temperatures of the system can be further improved.

[0038] A second aspect of the present invention provides an oil displacement agent prepared by processing the composition of the present invention.

[0039] The oil displacement agent prepared by this invention has the advantages of high phase transformation temperature and high viscosity at 130°C, which can significantly improve the crude oil recovery rate.

[0040] A third aspect of the present invention provides a method for preparing the oil displacement agent of the present invention, the method comprising:

[0041] a. Dissolve the synergist and stabilizer in water to obtain the first solution;

[0042] b. Dissolve the main agent in water to obtain a second solution;

[0043] c. Mix the first solution and the second solution to obtain the oil displacement agent.

[0044] The oil displacement agent prepared by this method can further improve its high-temperature viscosity and stability.

[0045] The fourth aspect of this invention provides the application of the oil displacement agent described herein in polymer flooding oil recovery from core samples.

[0046] Using the oil displacement agent of this invention for polymer flooding in core samples can significantly improve oil recovery.

[0047] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.

[0048] Unless otherwise specified, all conditions in the examples shall be performed under standard conditions or conditions recommended by the manufacturer. Unless otherwise stated, all raw materials used in the examples are commercially available products.

[0049] The viscosity testing method or instrument was as follows: The apparent viscosity of the oil displacement agent at 130°C was tested using a Fann 50SL high-temperature and high-pressure rheometer from Fann Instruments, Inc., with a shear rate of 50 s⁻¹. -1 ;

[0050] The phase transition temperature test method or instrument is as follows: The apparent viscosity of the oil displacement agent at 20–130 °C is tested using a Fann 50SL high-temperature and high-pressure rheometer from American Instruments. The heating rate is 2 °C / min, and the shear rate is 50 s. -1 The temperature at which the viscosity of the oil displacement agent suddenly increases is the phase transition temperature.

[0051] Assuming the mass of saturated oil in the simulated core is x1g, water flooding is used until the water production rate reaches 98%, at which point x2g of water-containing oil will precipitate. Heating the precipitated oil and water causes them to separate into layers, and the mass of the extracted oil is x3g. Therefore, the water flooding recovery rate is x3 / x1. After water flooding stops, an oil displacement agent is added for oil displacement, at which point x4g of oil containing the oil displacement agent will precipitate. Heating the precipitated oil causes it to separate into layers, and the mass of the extracted oil is x5g. Therefore, the final recovery rate is (x3+x5) / x1, and the enhanced oil recovery rate is x5 / x1.

[0052] Example 1

[0053] Add 0.2 parts thiourea and 0.05 parts boron nitride to 49.75 parts tap water, stir until fully dissolved to obtain the first solution. Then add 0.5 parts of a terpolymer of acrylamide, acryloylmorpholine, and vinylpyrrolidone (relative molecular mass 3.50 × 10⁻⁶) to 49.5 parts tap water. 6 The polymer raw materials contain 70% acrylamide, 20% acryloylmorpholine, and 10% vinylpyrrolidone to obtain a second solution. The two solutions are stirred evenly to obtain oil displacement agent A. The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 395.5 mPa·s, and the phase transition temperature is 111.0℃.

[0054] Oil recovery performance test: Using simulated oil-saturated cores (the viscosity of simulated oil at 50℃ was 3685.0 mPa·s), the experimental temperature was 130℃. The core model was an artificial cemented core, 30 cm in length and 2.5 cm in diameter, with a permeability of 2200 × 10⁻⁶. -3 μm 2 The pore volume ratio of the injected slug was 0.3; then, water flooding was performed on the core at a rate of 2.0 mL / min using a horizontal pump until a stable water flow was observed at both ends of the core. The calculated water flooding recovery rate was 38.6%. Next, high-temperature heat-sensitive polyacrylamide nanocomposite oil displacement agent was injected into the core at a rate of 2.0 mL / min using a horizontal pump to perform polymer flooding until a stable oil displacement agent flow was observed at both ends of the core. The calculated final recovery rate was 53.4%, and the oil displacement agent enhanced the recovery rate by 14.8%.

[0055] Example 2

[0056] Add 0.5 parts sodium sulfite and 1.0 part positively charged gel to 48.5 parts tap water, stir until fully dissolved to obtain the first solution. Then add 0.75 parts of a terpolymer of acrylamide, acryloylmorpholine, and vinylpyrrolidone (relative molecular mass 3.50 × 10⁻⁶) to 49.25 parts tap water. 6 The polymer raw materials contain 70% acrylamide, 20% acryloylmorpholine, and 10% vinylpyrrolidone to obtain a second solution. The two solutions are stirred evenly to obtain oil displacement agent B. The viscosity of this oil displacement agent after aging at 130℃ for 30 days is 398.5 mPa·s, and the phase transition temperature is 114.0℃.

[0057] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.5%; the calculated final recovery rate was 54.2%, and the oil displacement agent increased the recovery rate by 15.7%.

[0058] Example 3

[0059] Add 0.8 parts sodium thiosulfate and 1.0 part graphene to 48.2 parts tap water, stir until fully dissolved to obtain the first solution. Then add 1.25 parts of a terpolymer of acrylamide, acryloylmorpholine, and 2-acrylamido-2-methylpropanesulfonic acid (relative molecular mass 4.00 × 10⁻⁶) to 48.75 parts tap water. 6 The polymer raw materials contain 50% acrylamide, 20% acryloylmorpholine, and 30% 2-acrylamido-2-methylpropanesulfonic acid. A second solution is obtained by stirring the two solutions evenly to obtain oil displacement agent C. The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 399.5 mPa·s, and the phase transition temperature is 118.0℃.

[0060] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.6%; the calculated final recovery rate was 56.6%, and the oil displacement agent increased the recovery rate by 18.0%.

[0061] Example 4

[0062] Same as Example 1, except that: the main agent is a terpolymer of acrylamide, acryloylmorpholine, and vinylpyrrolidone (with a relative molecular mass of 3.50 × 10⁻⁶) in a mass ratio of 7:3. 6 The polymerization raw materials contain 70% acrylamide, 20% acryloylmorpholine, and 10% vinylpyrrolidone, and a terpolymer of acrylamide, acryloylmorpholine, and 2-acrylamido-2-methylpropanesulfonic acid (with a relative molecular mass of 4.00 × 10⁻⁶). 6 The polymer raw materials contain 50% acrylamide, 20% acryloylmorpholine, and 30% 2-acrylamido-2-methylpropanesulfonic acid to obtain oil displacement agent D.

[0063] The viscosity of this oil displacement agent after aging at 130℃ for 30 days is 384.0 mPa·s, and the phase transition temperature is 110℃.

[0064] Recovery effect test: Same as in Example 1, the waterflood recovery rate was calculated to be 38.6%; the final recovery rate was calculated to be 52.3%, and the oil displacement agent increased the recovery rate by 13.7%.

[0065] Example 5

[0066] Add 0.2 parts thiourea and 0.05 parts boron nitride to 49.75 parts tap water, stir until fully dissolved to obtain the first solution. Then add 0.5 parts of a terpolymer of acrylamide, acryloylmorpholine, and vinylpyrrolidone (relative molecular mass 1.50 × 10⁻⁶) to 49.5 parts tap water. 6The polymer raw materials contain 70% acrylamide, 20% acryloylmorpholine, and 10% vinylpyrrolidone to obtain a second solution. The two solutions are stirred evenly to obtain oil displacement agent E. The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 326.5 mPa·s, and the phase transition temperature is 108.0℃.

[0067] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.5%; the calculated final recovery rate was 49.9%, and the oil displacement agent increased the recovery rate by 11.4%.

[0068] Example 6

[0069] Add 0.2 parts thiourea and 0.05 parts boron nitride to 49.75 parts tap water, stir until fully dissolved to obtain the first solution. Then add 0.5 parts of a terpolymer of acrylamide, acryloylmorpholine, and vinylpyrrolidone (relative molecular mass 3.50 × 10⁻⁶) to 49.5 parts tap water. 6 The polymer raw materials contain 50% acrylamide, 40% acryloylmorpholine, and 10% vinylpyrrolidone to obtain a second solution. The two solutions are stirred evenly to obtain the oil displacement agent F. The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 328.0 mPa·s, and the phase transition temperature is 107.0℃.

[0070] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.6%; the calculated final recovery rate was 50.7%, and the oil displacement agent increased the recovery rate by 12.1%.

[0071] Example 7

[0072] Add 2.5 parts sodium sulfite and 1.5 parts positively charged gel to 46.0 parts tap water, stir until fully dissolved to obtain the first solution. Then add 3.8 parts of a terpolymer of acrylamide, acryloylmorpholine, and vinylpyrrolidone (relative molecular mass 3.50 × 10⁻⁶) to 46.2 parts tap water. 6 The polymer raw materials contain 70% acrylamide, 20% acryloylmorpholine, and 10% vinylpyrrolidone to obtain a second solution. The two solutions are stirred evenly to obtain the oil displacement agent G. The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 358.5 mPa·s, and the phase transition temperature is 109.0℃.

[0073] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.5%; the calculated final recovery rate was 50.1%, and the oil displacement agent increased the recovery rate by 11.6%.

[0074] Example 8

[0075] Add 1.0 part sodium thiosulfate and 1.4 parts graphene to 47.6 parts tap water, stir until fully dissolved, then add 49.5 parts tap water, followed by 0.5 parts a terpolymer of acrylamide, acryloylmorpholine, and 2-acrylamido-2-methylpropanesulfonic acid (relative molecular mass 4.00 × 10⁻⁶). 6 The polymer raw materials contain 50% acrylamide, 20% acryloylmorpholine, and 30% 2-acrylamido-2-methylpropanesulfonic acid to obtain oil displacement agent H. The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 320.0 mPa·s, and the phase transformation temperature is 107.0℃.

[0076] Recovery effect test: Same as in Example 1, the waterflood recovery rate was calculated to be 38.6%; the final recovery rate was calculated to be 51.3%, and the oil displacement agent increased the recovery rate by 12.7%.

[0077] Comparative Example 1

[0078] Add 0.8 parts sodium sulfite and 1.0 part positively charged gel to 48.2 parts tap water, stir well to fully dissolve, and obtain the first solution. Then add 0.5 parts anionic polyacrylamide (relative molecular mass 800×10⁻⁶) to 49.5 parts tap water. 4 (25% hydrolysis) to obtain a second solution. Stir the two solutions evenly to obtain polyacrylamide oil displacement agent-1. The viscosity of this oil displacement agent after aging at 130℃ for 30 days is 3.1 mPa·s; the phase transition temperature is 62℃.

[0079] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.6%; the calculated final recovery rate was 44.9%, and the oil displacement agent increased the recovery rate by 6.3%.

[0080] Comparative Example 2

[0081] Same as Example 1, except that the stabilizer thiourea was not used, and other conditions remained the same, to obtain oil displacement agent-2.

[0082] The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 114.2 mPa·s; the phase transition temperature is 98℃.

[0083] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.5%; the calculated final recovery rate was 45.7%, and the oil displacement agent increased the recovery rate by 7.2%.

[0084] Comparative Example 3

[0085] Same as Example 1, except that the synergist boron nitride was not used, and other conditions remained unchanged, resulting in oil displacement agent-3.

[0086] The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 131.6 mPa·s; the phase transition temperature is 105℃.

[0087] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.5%; the calculated final recovery rate was 46.8%, and the oil displacement agent increased the recovery rate by 8.3%.

[0088] Comparative Example 4

[0089] Similar to Example 1, except that the main ingredient is a binary polymer of acrylamide and acryloylmorpholine, and other conditions remain unchanged, resulting in oil displacement agent-4.

[0090] The viscosity of the oil displacement agent after aging at 130℃ for 30 days is 116.4 mPa·s; the phase transition temperature is 96℃.

[0091] Recovery effect test: Same as in Example 1, the calculated waterflood recovery rate was 38.6%; the calculated final recovery rate was 45.4%, and the oil displacement agent increased the recovery rate by 6.8%.

[0092] As can be seen from the above embodiments, the oil displacement agent prepared by the present invention, compared with the comparative examples 1-4 that do not use the present invention, can significantly improve the phase transition temperature and viscosity at high temperature of the system by using the present invention.

[0093] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composition for preparing an oil displacement agent, characterized in that, The composition comprises a main agent, a synergist, and a stabilizer, wherein the main agent comprises a terpolymer A obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine, and vinylpyrrolidone; and / or a terpolymer B obtained by copolymerization of raw materials containing acrylamide, acrylomorpholine, and 2-acrylamido-2-methylpropanesulfonic acid; In the raw materials of the terpolymer A, based on a mass percentage of 100%, acrylamide accounts for 40-70 wt%, acryloylmorpholine accounts for 20-30 wt%, and vinylpyrrolidone accounts for 10-30 wt%. In the raw materials of the terpolymer B, based on 100% by mass, acrylamide accounts for 40-70 wt%, acryloylmorpholine accounts for 20-30 wt%, and 2-acrylamido-2-methylpropanesulfonic acid accounts for 10-30 wt%; The synergist includes at least one of boron nitride, positively charged gel, and graphene; The stabilizer includes at least one of sodium sulfite, thiourea, and sodium thiosulfate.

2. The composition according to claim 1, wherein, The main agent is a mixture of terpolymer A and terpolymer B.

3. The composition according to claim 2, wherein, The mass ratio of terpolymer A to terpolymer B is 1-9:

1.

4. The composition according to claim 1 or 2, wherein, The relative molecular mass of the terpolymer A is 2.30 × 10⁻⁶. 6 -4.50×10 6 ; and / or The relative molecular mass of the terpolymer B is 2.30 × 10⁻⁶. 6 -4.50×10 6 .

5. The composition according to claim 1 or 2, wherein, The composition comprises, in 100 parts by weight: 0.2-2.0 parts by weight of the main agent, 0.01-3.0 parts by weight of the synergist, 0.05-2.0 parts by weight of the stabilizer, and the balance being water.

6. The composition according to claim 1 or 2, wherein, The composition comprises, in 100 parts by weight: 0.5-1.25 parts by weight of the main agent, 0.05-1.0 parts by weight of the synergist, 0.2-0.8 parts by weight of the stabilizer, and the balance being water.

7. An oil displacement agent prepared by processing the composition according to any one of claims 1-6.

8. A method for preparing the oil displacement agent according to claim 7, characterized in that, The method includes: a. Dissolve the synergist and stabilizer in water to obtain the first solution; b. Dissolve the main agent in water to obtain a second solution; c. Mix the first solution and the second solution to obtain the oil displacement agent.

9. The application of the oil displacement agent according to claim 7 in polymer flooding oil recovery from core samples.