Carboxyl modified nano oil displacement agent, preparation method thereof, oil displacement system and application thereof

Abstract

The application discloses a carboxyl modified nano oil displacement agent which is composed of a nano silicon dioxide skeleton and a functional group connected to the nano silicon dioxide skeleton, wherein the functional group is -RCOOM, R is CH2 or C2H4, and M is one of Li, K and Na. The application also discloses a preparation method of the carboxyl modified nano oil displacement agent, which comprises the following steps: (1) preparing a hydroxyl silicon dioxide nanoparticle dispersion liquid; (2) preparing an amino modified nano silicon dioxide solution, and obtaining amino modified nano silicon dioxide particles after first post-treatment; and (3) dispersing the amino modified nano silicon dioxide particles in water, adding a halogen acetic acid monovalent salt, and then performing reaction and second post-treatment to obtain the carboxyl modified nano oil displacement agent. The oil displacement system is composed of the carboxyl modified nano oil displacement agent, a polymer, a surfactant and water, wherein the carboxyl modified nano oil displacement agent accounts for 0.05-0.3%, the polymer accounts for 0.1-0.3%, the surfactant accounts for 0.1-1%, and the rest is water.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to carboxyl-modified nano-oil displacement agents, their preparation methods, oil displacement systems, and their applications. Background Technology

[0002] Most of my country's water-injection oilfields have entered the high water-cut development stage, and more than 60% of the geological reserves require tertiary oil recovery for extraction. Tertiary oil recovery is a technology used to enhance crude oil recovery by injecting gases, chemicals, microorganisms, or steam.

[0003] In tertiary oil recovery, chemical flooding can improve oil recovery by 10% to 19%, showing great potential and being a major method for enhancing oil recovery. However, due to the high temperature, high salinity, and complex produced water conditions in reservoirs where chemical flooding is implemented, the application of chemical flooding technology faces severe challenges.

[0004] Chinese invention patent application CN 102372820A discloses a polymerizable functional monomer and its synthesis method. The prepared polymerizable functional monomer can be used to synthesize long-chain branched polymers for tertiary oil recovery, ultimately producing a binary composite oil displacement agent for tertiary oil recovery. However, under high-temperature and high-salinity reservoir conditions, the viscosity of the polymer used for oil displacement suffers severe loss, requiring increased dosage and increasing oil recovery costs.

[0005] Chinese invention patent application CN 101942297A discloses a fatty amide phosphate potassium betaine surfactant for tertiary oil recovery, its preparation method, and its application. The fatty amide phosphate potassium betaine surfactant has the following structural formula: Wherein: R1 is an alkyl group of C13 to C23; R2 is an alkyl group of C12 to C20. However, the above-mentioned surfactants for oil displacement also have problems such as poor temperature and salt resistance and low oil washing efficiency.

[0006] Nanotechnology is a new type of science and technology that emerged in the late 1980s and has rapidly risen to prominence. With the continuous development of nanotechnology and the emergence of nanomaterials, nanotechnology is penetrating into various fields and has entered the field of oil development, with nano-enhanced oil recovery systems receiving widespread attention.

[0007] Chinese invention patent application CN103725278A discloses a method for preparing a nano-oil displacement agent with stable temperature and salt resistance. Polyacrylamide is modified onto the surface of silica nanoparticles through chemical bonds to obtain stable nanocomposite particles, which are then combined with alkali and surfactant to prepare a nano-oil displacement agent.

[0008] Chinese invention patent application CN103160268A discloses a nano-silica / polymer oil displacement agent and its synthesis method. This oil displacement agent is a terpolymer composed of acrylamide, acrylic acid, and nano-silica functional monomers. The mass percentages of the raw materials used are: acrylamide 60.5%-69.9%, acrylic acid 30%-35%, and nano-silica functional monomers 0.1%-4.5%. The synthesis method is as follows: First, nano-silica functional monomers, acrylamide, and acrylic acid are added to a three-necked flask. The pH is adjusted to 7.0-7.5 with sodium hydroxide solution to prepare a solution with a total monomer mass concentration of 10%-20%. Nitrogen gas is purged for 45 minutes. Then, an initiator is added, and the reaction is carried out at 30-55℃ for 4-8 hours. Finally, the mixture is washed with anhydrous ethanol, dried, and pulverized to obtain the terpolymer. The terpolymer exhibits strong shear resistance and good temperature and salt resistance.

[0009] Cheng Yamin et al. reported a nano-silica oil displacement agent grafted with polymer chains in the paper "Synthesis and Properties of Polyacrylamide / 2-acrylamide-2-methyl-propanesulfonate Polymer Grafted Nano-SiO2 Oil Displacement Agent" published in the journal Chemical Research, Vol. 28, No. 2, 2017. The agent can improve the displacement efficiency of reservoirs after water flooding when the concentration is above 0.1%.

[0010] These publicly reported nano-oil displacement agents all utilize the surface effect of nanoparticles to introduce polymers onto the surface of nano-silica, thereby improving the performance of the polymers. However, none of them have considered the effect of nanoparticles on surfactants, which would affect their application effect.

[0011] This invention addresses the shortcomings of current nano-displacement oil systems by developing a carboxyl-modified nano-displacement agent that can significantly improve the performance of surfactants. This agent can simultaneously increase the viscosity and calcium resistance of polymers, effectively enhancing the recovery rate of high-temperature and high-salinity oil reservoirs. Summary of the Invention

[0012] Purpose of the invention: To address the shortcomings of the prior art, this invention discloses a carboxyl-modified nano-oil displacement agent, its preparation method, oil displacement system, and its application, wherein:

[0013] The carboxyl-modified nano-oil displacement agent disclosed in this invention can significantly improve the performance of surfactants and polymers under high temperature and high salt conditions.

[0014] Technical solution: Carboxyl-modified nano-oil displacement agent, wherein the carboxyl-modified nano-oil displacement agent is composed of a nano-silica framework and functional groups attached to the nano-silica framework, wherein the functional group is -RCOOM, R is CH2 or C2H4, and M is one of Li, K, and Na. The structural formula of the carboxyl-modified nano-oil displacement agent is as follows:

[0015]

[0016] A method for preparing carboxyl-modified nano-oil displacement agent, by weight, includes the following steps:

[0017] (1) Mix water and L-arginine evenly, then add tetraethyl orthosilicate, stir evenly and heat to the reaction temperature for a period of time to obtain a dispersion of hydroxyl silica nanoparticles.

[0018] (2) Add an appropriate amount of 3-aminopropyltrimethoxysilane to the hydroxyl silica nanoparticle dispersion obtained in step (1), and continue to react for a period of time to obtain an amino-modified nano silica solution. Then perform a first post-treatment to obtain amino-modified nano silica particles.

[0019] (3) The amino-modified nano-silica particles obtained in step (2) are dispersed in an appropriate amount of water, and then a haloacetic acid monovalent salt is added to it. After reacting for a period of time under stirring conditions and at a certain reaction temperature, an aqueous solution of the nano-oil displacement agent is obtained. Then, it is subjected to a second post-treatment to obtain the carboxyl-modified nano-oil displacement agent, wherein:

[0020] The structural formula of the monovalent salt of haloacetic acid is in:

[0021] X is one or more of F, Cl, Br, and I;

[0022] R is CH2 or C2H4;

[0023] M is one of Li, K, and Na.

[0024] Further, in step (1), the mass ratio of water, L-arginine, and tetraethyl orthosilicate is (60–100):0.1:(5–40), and / or

[0025] In step (1), continuous stirring is performed at a speed of at least 500 rpm, preferably 500-600 rpm, and / or

[0026] The reaction temperature in step (1) is at least 70°C, preferably 70–80°C, and / or

[0027] The reaction time in step (1) is at least 20 hours, preferably 20 to 24 hours, and / or

[0028] The water mentioned in step (1) is one of deionized water, distilled water, and ultrapure water.

[0029] Furthermore, the mass ratio of the amount of 3-aminopropyltrimethoxysilane added in step (2) to the amount of L-arginine added in step (1) is 4:0.1, and / or

[0030] In step (2), continuous stirring is performed at a speed of at least 500 rpm, preferably 500-600 rpm, and / or

[0031] The reaction temperature in step (2) is at least 70°C, preferably 70–80°C, and / or

[0032] The reaction time in step (2) is at least 20 hours, preferably 20 to 24 hours.

[0033] Furthermore, the specific steps of the first post-processing in step (2) are as follows:

[0034] The amino-modified nano-silica solution was centrifuged to precipitate, washed at least three times with ethanol and water respectively, and then vacuum-dried overnight at at least 25°C, preferably 25°C to 40°C.

[0035] The water used for washing is deionized water or distilled water.

[0036] Further, in step (3), the mass ratio of amino-modified nano-silica particles, water, and haloacetic acid monovalent salt is 2:(50-80):(2-8), and / or

[0037] In step (3), continuous stirring is performed at a speed of at least 500 rpm, preferably 500-600 rpm, and / or

[0038] The reaction temperature in step (3) is at least 70°C, preferably 70–80°C, and / or

[0039] The reaction time in step (3) is at least 20 hours, preferably 20 to 24 hours, and / or

[0040] The water mentioned in step (1) is one of deionized water, distilled water, and ultrapure water.

[0041] Furthermore, the specific steps of the second post-processing in step (3) are as follows:

[0042] After centrifuging the aqueous solution of the nano-oil displacement agent, it is washed with water at least three times, and then vacuum dried overnight at at least 25°C, preferably 25°C to 40°C.

[0043] The water used for washing is deionized water or distilled water.

[0044] The carboxyl-modified nano-oil displacement agent is prepared by any one of the preparation methods described above.

[0045] The oil displacement system comprises the carboxyl-modified nano-oil displacement agent, a polymer, a surfactant, and water, wherein:

[0046] Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.05% to 0.3%, the polymer accounts for 0.1% to 0.3%, the surfactant accounts for 0.1% to 1%, and the balance is water.

[0047] Preferably, the carboxyl-modified nano-oil displacement agent accounts for 0.05% to 0.2%, the polymer accounts for 0.15% to 0.25%, the surfactant accounts for 0.2% to 0.4%, and the balance is water.

[0048] Further, the polymer is one of partially hydrolyzed polyacrylamide (HPAM) with a molecular weight of 10 million to 35 million, modified polyacrylamide (M-HPAM) with a molecular weight of 10 million to 35 million, and hydrophobic associative polymer (HAWP) with a molecular weight of 10 million to 35 million.

[0049] Furthermore, the surfactant is one or more of petroleum sulfonate, alkylbenzene sulfonate, olefin sulfonate, polyoxyethylene ether sulfonate, and polyoxyethylene ether carboxylate.

[0050] Furthermore, the water is injected water or simulated formation water.

[0051] The above-mentioned oil displacement system is used as an oil displacement agent in the exploitation of high-temperature and high-salinity oil reservoirs.

[0052] An oil extraction method involves injecting the aforementioned oil displacement system into a high-temperature, high-salinity oil reservoir.

[0053] Beneficial effects: Compared with the prior art, the carboxyl-modified nano-oil displacement agent, its preparation method, oil displacement system, and its application disclosed in this invention have the following beneficial effects:

[0054] (1) The carboxyl-modified nano-oil displacement agent prepared by the present invention has small particle size, good dispersion performance, and an average particle size of about 25 nm. It can also exist in a monodisperse form in aqueous solution.

[0055] (2) The carboxyl-modified nano-oil displacement agent prepared by the present invention can significantly improve the interfacial activity and oil washing efficiency of the surfactant, and can also improve the viscosity and calcium resistance of the polymer, thus meeting the requirements of significantly improving the recovery rate of high-temperature and high-salinity oil reservoirs. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the particle size distribution of amino-modified nanoparticles (SNP-NH2).

[0057] Figure 2 This is a schematic diagram of the particle size distribution of carboxyl-modified nano-oil displacement agent (SNP-COONa), where three colors represent the test results of three repeated experiments.

[0058] Figure 3This is a schematic diagram illustrating the synergistic effect of carboxyl-modified nano-oil displacement agent and petroleum sulfonate in reducing oil-water interfacial tension.

[0059] Figure 4 This is a schematic diagram showing the test results of the effect of carboxyl-modified nano-oil displacement agent on the viscosity of the polymer phase. Detailed Implementation

[0060] The specific embodiments of the present invention are described in detail below.

[0061] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0062] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0063] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0064] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0065] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0066] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0067] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0068] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0069] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0070] Example 1

[0071] A carboxyl-modified nano-oil displacement agent, comprising a nano-silica framework and functional groups attached to the nano-silica framework, wherein the functional group is -RCOOM, R is CH2, and M is Li, and the structural formula of the carboxyl-modified nano-oil displacement agent is as follows:

[0072]

[0073] A method for preparing carboxyl-modified nano-oil displacement agent, by weight, includes the following steps:

[0074] (1) Mix water and L-arginine evenly, then add tetraethyl orthosilicate, stir evenly and heat to the reaction temperature for a period of time to obtain a dispersion of hydroxyl silica nanoparticles.

[0075] (2) Add an appropriate amount of 3-aminopropyltrimethoxysilane to the hydroxyl silica nanoparticle dispersion obtained in step (1), and continue to react for a period of time to obtain an amino-modified nano silica solution. Then perform a first post-treatment to obtain amino-modified nano silica particles.

[0076] (3) The amino-modified nano-silica particles obtained in step (2) are dispersed in an appropriate amount of water, and then a haloacetic acid monovalent salt is added to it. After reacting for a period of time under stirring conditions and at a certain reaction temperature, an aqueous solution of the nano-oil displacement agent is obtained. Then, it is subjected to a second post-treatment to obtain the carboxyl-modified nano-oil displacement agent, wherein:

[0077] The structural formula of the monovalent salt of haloacetic acid is in:

[0078] X is F;

[0079] R is CH2;

[0080] M is Li.

[0081] Further, in step (1), the mass ratio of water, L-arginine, and tetraethyl orthosilicate is 60:0.1:5, and / or

[0082] In step (1), continuous stirring is performed at a speed of 500 rpm, and / or

[0083] The reaction temperature in step (1) is 70°C, and / or

[0084] The reaction time in step (1) is 24 hours;

[0085] The water mentioned in step (1) is ultrapure water.

[0086] Furthermore, the mass ratio of the amount of 3-aminopropyltrimethoxysilane added in step (2) to the amount of L-arginine added in step (1) is 4:0.1, and / or

[0087] In step (2), continuous stirring is performed at a speed of 500 rpm, and / or

[0088] The reaction temperature in step (2) is 70℃ and / or

[0089] The reaction time in step (2) is 24 hours.

[0090] Furthermore, the specific steps of the first post-processing in step (2) are as follows:

[0091] The amino-modified nano-silica solution was centrifuged to precipitate, washed three times each with ethanol and deionized water, and then vacuum dried overnight at 25°C.

[0092] Furthermore, in step (3), the mass ratio of amino-modified nano-silica particles, water, and haloacetic acid monovalent salt is 2:50:2, and / or

[0093] In step (3), continuous stirring is performed at a speed of 500 rpm, and / or

[0094] The reaction temperature in step (3) is 70°C, and / or

[0095] The reaction time in step (3) is 24 hours;

[0096] The water mentioned in step (3) is ultrapure water.

[0097] Furthermore, the specific steps of the second post-processing in step (3) are as follows:

[0098] After centrifuging the aqueous solution of the nano-oil displacement agent, it was washed four times with deionized water and then vacuum dried overnight at 25°C.

[0099] The carboxyl-modified nano-oil displacement agent is prepared by any one of the preparation methods described above.

[0100] The oil displacement system comprises the carboxyl-modified nano-oil displacement agent, a polymer, a surfactant, and water, wherein:

[0101] Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.05%, the polymer accounts for 0.1%, the surfactant accounts for 0.1%, and the remainder is water.

[0102] In another embodiment, the oil displacement system comprises the carboxyl-modified nano-oil displacement agent, a polymer, a surfactant, and water, wherein:

[0103] Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.05%, the polymer accounts for 0.15%, the surfactant accounts for 0.2%, and the remainder is water.

[0104] Furthermore, the polymer is partially hydrolyzed polyacrylamide (HPAM) with a molecular weight of 10 million.

[0105] Furthermore, the surfactant is a petroleum sulfonate.

[0106] Furthermore, the water in question is injected water.

[0107] The above-mentioned oil displacement system is used as an oil displacement agent in the exploitation of high-temperature and high-salinity oil reservoirs.

[0108] An oil extraction method involves injecting the aforementioned oil displacement system into a high-temperature, high-salinity oil reservoir.

[0109] Example 2

[0110] A carboxyl-modified nano-oil displacement agent, comprising a nano-silica framework and functional groups attached to the nano-silica framework, wherein the functional group is -RCOOM, R is C2H4, and M is K, and the structural formula of the carboxyl-modified nano-oil displacement agent is as follows:

[0111]

[0112] A method for preparing carboxyl-modified nano-oil displacement agent, by weight, includes the following steps:

[0113] (1) Mix water and L-arginine evenly, then add tetraethyl orthosilicate, stir evenly and heat to the reaction temperature for a period of time to obtain a dispersion of hydroxyl silica nanoparticles.

[0114] (2) Add an appropriate amount of 3-aminopropyltrimethoxysilane to the hydroxyl silica nanoparticle dispersion obtained in step (1), and continue to react for a period of time to obtain an amino-modified nano silica solution. Then perform a first post-treatment to obtain amino-modified nano silica particles.

[0115] (3) The amino-modified nano-silica particles obtained in step (2) are dispersed in an appropriate amount of water, and then a haloacetic acid monovalent salt is added to it. After reacting for a period of time under stirring conditions and at a certain reaction temperature, an aqueous solution of the nano-oil displacement agent is obtained. Then, it is subjected to a second post-treatment to obtain the carboxyl-modified nano-oil displacement agent, wherein:

[0116] The structural formula of the monovalent salt of haloacetic acid is in:

[0117] X is Cl;

[0118] R is C2H4;

[0119] M is K.

[0120] Further, in step (1), the mass ratio of water, L-arginine, and tetraethyl orthosilicate is 100:0.1:40, and / or

[0121] In step (1), continuous stirring is performed at a speed of 600 rpm, and / or

[0122] The reaction temperature in step (1) is 80°C, and / or

[0123] The reaction time in step (1) is 20 hours;

[0124] The water mentioned in step (1) is deionized water.

[0125] Furthermore, the mass ratio of the amount of 3-aminopropyltrimethoxysilane added in step (2) to the amount of L-arginine added in step (1) is 4:0.1, and / or

[0126] In step (2), continuous stirring is performed at a speed of 600 rpm, and / or

[0127] The reaction temperature in step (2) is 80°C, and / or

[0128] The reaction time in step (2) is 20 hours.

[0129] Furthermore, the specific steps of the first post-processing in step (2) are as follows:

[0130] The amino-modified nano-silica solution was centrifuged to precipitate, washed five times each with ethanol and distilled water, and then vacuum dried overnight at 40°C.

[0131] Furthermore, in step (3), the mass ratio of amino-modified nano-silica particles, water, and haloacetic acid monovalent salt is 2:80:8, and / or

[0132] In step (3), continuous stirring is performed at a speed of 600 rpm, and / or

[0133] The reaction temperature in step (3) is 80°C, and / or

[0134] The reaction time in step (3) is 20 hours;

[0135] The water mentioned in step (3) is deionized water.

[0136] Furthermore, the specific steps of the second post-processing in step (3) are as follows:

[0137] After centrifuging the aqueous solution of the nano-oil displacement agent, it was washed three times with distilled water and then vacuum dried overnight at 40°C.

[0138] The carboxyl-modified nano-oil displacement agent is prepared by any one of the preparation methods described above.

[0139] The oil displacement system comprises the carboxyl-modified nano-oil displacement agent, a polymer, a surfactant, and water, wherein:

[0140] Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.3%, the polymer accounts for 0.3%, the surfactant accounts for 1%, and the remainder is water.

[0141] In another embodiment, the oil displacement system comprises the carboxyl-modified nano-oil displacement agent, a polymer, a surfactant, and water, wherein:

[0142] Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.2%, the polymer accounts for 0.25%, the surfactant accounts for 0.4%, and the remainder is water.

[0143] Furthermore, the polymer is a hydrophobic associative polymer (HAWP) with a molecular weight of 35 million.

[0144] Furthermore, the surfactant is an alkylbenzene sulfonate.

[0145] Furthermore, the water in question is simulated formation water.

[0146] The above-mentioned oil displacement system is used as an oil displacement agent in the exploitation of high-temperature and high-salinity oil reservoirs.

[0147] An oil extraction method involves injecting the aforementioned oil displacement system into a high-temperature, high-salinity oil reservoir.

[0148] Example 3

[0149] A carboxyl-modified nano-oil displacement agent, comprising a nano-silica framework and functional groups attached to the nano-silica framework, wherein the functional group is -RCOOM, R is CH2, and M is Na; the structural formula of the carboxyl-modified nano-oil displacement agent is as follows:

[0150]

[0151] A method for preparing carboxyl-modified nano-oil displacement agent, by weight, includes the following steps:

[0152] (1) Mix water and L-arginine evenly, then add tetraethyl orthosilicate, stir evenly and heat to the reaction temperature for a period of time to obtain a dispersion of hydroxyl silica nanoparticles.

[0153] (2) Add an appropriate amount of 3-aminopropyltrimethoxysilane to the hydroxyl silica nanoparticle dispersion obtained in step (1), and continue to react for a period of time to obtain an amino-modified nano silica solution. Then perform a first post-treatment to obtain amino-modified nano silica particles.

[0154] (3) The amino-modified nano-silica particles obtained in step (2) are dispersed in an appropriate amount of water, and then a haloacetic acid monovalent salt is added to it. After reacting for a period of time under stirring conditions and at a certain reaction temperature, an aqueous solution of the nano-oil displacement agent is obtained. Then, it is subjected to a second post-treatment to obtain the carboxyl-modified nano-oil displacement agent, wherein:

[0155] The structural formula of the monovalent salt of haloacetic acid is in:

[0156] X is Br;

[0157] R is CH2;

[0158] M is Na.

[0159] Further, in step (1), the mass ratio of water, L-arginine, and tetraethyl orthosilicate is 80:0.1:19.9, and / or

[0160] In step (1), continuous stirring is performed at a speed of 550 rpm, and / or

[0161] The reaction temperature in step (1) is 75°C, and / or

[0162] The reaction time in step (1) is 22 hours;

[0163] The water mentioned in step (1) is distilled water.

[0164] Furthermore, the mass ratio of the amount of 3-aminopropyltrimethoxysilane added in step (2) to the amount of L-arginine added in step (1) is 4:0.1, and / or

[0165] In step (2), continuous stirring is performed at a speed of 550 rpm, and / or

[0166] The reaction temperature in step (2) is 75°C, and / or

[0167] The reaction time in step (2) is 22 hours.

[0168] Furthermore, the specific steps of the first post-processing in step (2) are as follows:

[0169] The amino-modified nano-silica solution was centrifuged to precipitate, washed three times each with ethanol and deionized water, and then vacuum dried overnight at 30°C.

[0170] Furthermore, in step (3), the mass ratio of amino-modified nano-silica particles, water, and haloacetic acid monovalent salt is 2:74:4, and / or

[0171] In step (3), continuous stirring is performed at a speed of 550 rpm, and / or

[0172] The reaction temperature in step (3) is 75°C, and / or

[0173] The reaction time in step (3) is 22 hours;

[0174] The water mentioned in step (3) is dedistilled water.

[0175] Furthermore, the specific steps of the second post-processing in step (3) are as follows:

[0176] After centrifuging the aqueous solution of the nano-oil displacement agent, it was washed four times with deionized water and then vacuum dried overnight at 30°C.

[0177] The carboxyl-modified nano-oil displacement agent is prepared by any one of the preparation methods described above.

[0178] The oil displacement system comprises the carboxyl-modified nano-oil displacement agent, a polymer, a surfactant, and water, wherein:

[0179] Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.15%, the polymer accounts for 0.2%, the surfactant accounts for 0.3%, and the remainder is water.

[0180] Furthermore, the polymer is a hydrophobic associative polymer (HAWP) with a molecular weight of 15 million.

[0181] Furthermore, the surfactant is an olefin sulfonate.

[0182] Furthermore, the water in question is injected water.

[0183] The above-mentioned oil displacement system is used as an oil displacement agent in the exploitation of high-temperature and high-salinity oil reservoirs.

[0184] An oil extraction method involves injecting the aforementioned oil displacement system into a high-temperature, high-salinity oil reservoir.

[0185] Example 4

[0186] A carboxyl-modified nano-oil displacement agent, comprising a nano-silica framework and functional groups attached to the nano-silica framework, wherein the functional group is -RCOOM, R is CH2, and M is Li, and the structural formula of the carboxyl-modified nano-oil displacement agent is as follows:

[0187]

[0188] A method for preparing carboxyl-modified nano-oil displacement agent, by weight, includes the following steps:

[0189] (1) Mix water and L-arginine evenly, then add tetraethyl orthosilicate, stir evenly and heat to the reaction temperature for a period of time to obtain a dispersion of hydroxyl silica nanoparticles.

[0190] (2) Add an appropriate amount of 3-aminopropyltrimethoxysilane to the hydroxyl silica nanoparticle dispersion obtained in step (1), and continue to react for a period of time to obtain an amino-modified nano silica solution. Then perform a first post-treatment to obtain amino-modified nano silica particles.

[0191] (3) The amino-modified nano-silica particles obtained in step (2) are dispersed in an appropriate amount of water, and then a haloacetic acid monovalent salt is added to it. After reacting for a period of time under stirring conditions and at a certain reaction temperature, an aqueous solution of the nano-oil displacement agent is obtained. Then, it is subjected to a second post-treatment to obtain the carboxyl-modified nano-oil displacement agent, wherein:

[0192] The structural formula of the monovalent salt of haloacetic acid is in:

[0193] X is I; in another embodiment, X is F, Cl, Br, and I in equimolar ratio.

[0194] R is CH2;

[0195] M is Li;

[0196] Further, in step (1), the mass ratio of water, L-arginine, and tetraethyl orthosilicate is 70:0.1:29.9, and / or

[0197] In step (1), continuous stirring is performed at a speed of 800 rpm, and / or

[0198] The reaction temperature in step (1) is 85°C, and / or

[0199] The reaction time in step (1) is 20 hours;

[0200] The water mentioned in step (1) is deionized water.

[0201] Furthermore, the mass ratio of the amount of 3-aminopropyltrimethoxysilane added in step (2) to the amount of L-arginine added in step (1) is 4:0.1, and / or

[0202] In step (2), continuous stirring is performed at a speed of 700 rpm, and / or

[0203] The reaction temperature in step (2) is 70°C, and / or

[0204] The reaction time in step (2) is 20 hours.

[0205] Furthermore, the specific steps of the first post-processing in step (2) are as follows:

[0206] The amino-modified nano-silica solution was centrifuged to precipitate, washed three times each with ethanol and deionized water, and then vacuum dried overnight at 30°C.

[0207] Furthermore, in step (3), the mass ratio of amino-modified nano-silica particles, water, and haloacetic acid monovalent salt is 2:60:2, and / or

[0208] In step (3), continuous stirring is performed at a speed of 700 rpm, and / or

[0209] The reaction temperature in step (3) is 70°C, and / or

[0210] The reaction time in step (3) is 20 hours;

[0211] The water mentioned in step (3) is distilled water.

[0212] Furthermore, the specific steps of the second post-processing in step (3) are as follows:

[0213] After centrifuging the aqueous solution of the nano-oil displacement agent, it was washed three times with deionized water and then vacuum dried overnight at 35°C.

[0214] The carboxyl-modified nano-oil displacement agent is prepared by any one of the preparation methods described above.

[0215] The oil displacement system comprises the carboxyl-modified nano-oil displacement agent, a polymer, a surfactant, and water, wherein:

[0216] Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.05%, the polymer accounts for 0.3%, the surfactant accounts for 0.4%, and the remainder is water.

[0217] Further, the polymer is a partially hydrolyzed polyacrylamide (HPAM) with a molecular weight of 15 million. In another embodiment, the polymer is a modified polyacrylamide (M-HPAM) with a molecular weight of 25 million. In another embodiment, the polymer is a hydrophobic associating polymer (HAWP) with a molecular weight of 15 million. In another embodiment, the polymer is a partially hydrolyzed polyacrylamide with a molecular weight of 10.05 million. In another embodiment, the polymer is a partially hydrolyzed polyacrylamide with a molecular weight of 34.95 million. In another embodiment, the polymer is a partially hydrolyzed polyacrylamide with a molecular weight of 25 million. In another embodiment, the polymer is a modified polyacrylamide with a molecular weight of 10.05 million. In another embodiment, the polymer is a modified polyacrylamide with a molecular weight of 34.95 million. In another embodiment, the polymer is a modified polyacrylamide with a molecular weight of 26 million. In another embodiment, the polymer is a hydrophobic associating polymer with a molecular weight of 10.05 million. In another embodiment, the polymer is a hydrophobic associating polymer with a molecular weight of 34.9 million. In another embodiment, the polymer is a hydrophobic associating polymer with a molecular weight of 18 million.

[0218] Further, the surfactant is a mixture of petroleum sulfonate, alkylbenzene sulfonate, olefin sulfonate, polyoxyethylene ether sulfonate, and polyoxyethylene ether carboxylate in equal mass ratios. In another embodiment, the surfactant is a polyoxyethylene ether sulfonate. In yet another embodiment, the surfactant is a polyoxyethylene ether carboxylate.

[0219] Furthermore, the water in question is simulated formation water.

[0220] The above-mentioned oil displacement system is used as an oil displacement agent in the exploitation of high-temperature and high-salinity oil reservoirs.

[0221] An oil extraction method involves injecting the aforementioned oil displacement system into a high-temperature, high-salinity oil reservoir.

[0222] Example 5

[0223] The preparation method of carboxyl-modified nano-oil displacement agent includes the following steps:

[0224] (1) In a three-necked flask, add 174g of deionized water and 0.174g of L-arginine. Slowly add 20g of tetraethyl orthosilicate to the system under mechanical stirring at 550rpm at room temperature. After the system is fully mixed, heat to 80℃ and reflux for 24h to obtain a dispersion of hydroxyl silica nanoparticles.

[0225] (2) 8g of 3-aminopropyltrimethoxysilane was slowly added directly to the above hydroxyl silica nanoparticle dispersion. The reaction conditions were kept unchanged, and the reaction was continued for 24h to obtain an amino-modified nano silica dispersion. The dispersion was centrifuged to obtain amino-modified silica solid. Ethanol was added to dissolve the solid, and the mixture was centrifuged and the supernatant was removed. This process was repeated three times. Deionized water was used as the solvent to repeat the process three more times. The obtained solid particles were placed in a vacuum oven at 40℃ and dried for 12h to obtain amino-modified nano silica particles.

[0226] (3) In a three-necked flask, add 2g of the amino-modified nanoparticles obtained in step (2) and 50mL of deionized water, then add 4.6g of sodium chloroacetate solid and mix the system thoroughly. Under mechanical stirring at 550rpm, heat the system to 80℃ and react for 24h to obtain carboxyl-modified silica nanoparticles. Wash and purify the modified nanoparticles three times with deionized water as solvent. Place the obtained solid particles in a vacuum oven at 40℃ and dry for 12h to obtain the carboxyl-modified nano oil displacement agent, named SNP-COONa.

[0227] Performance testing and characterization

[0228] Test Example 1: Particle Size Test

[0229] 1. 50 mg of the amino-modified silica nanoparticles synthesized in step (2) of Example 5 were dispersed in 10 mL of deionized water (0.5 wt%) and sonicated for 10 min to obtain an amino-modified silica nanoparticle dispersion. The particle size distribution of the nanoparticles was determined using a Zetasizer Nano ZSP laser light scattering instrument, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the amino-modified silica nanoparticles have uniform particle size and good monodispersity, with a mode particle size of 23.68 nm.

[0230] 2. 50 mg of the synthesized carboxyl-modified nano-oil displacement agent was dispersed in 10 mL of deionized water (0.5 wt%) and sonicated for 10 min to obtain a dispersion of the carboxyl-modified nano-oil displacement agent. The particle size distribution of the carboxyl-modified nano-oil displacement agent was determined using a Zetasizer Nano ZSP laser light scattering instrument. The above experiment was repeated three times, and the results are as follows. Figure 2 As shown. From Figure 2 It can be seen that the carboxyl-modified nano-oil displacement agent has uniform particle size and good monodispersity, with a mode particle size of about 20 nm.

[0231] Test Example 2: Oil-Water Interfacial Tension

[0232] The carboxyl-modified nano-oil displacement agent obtained in Example 5 was compounded with petroleum sulfonate for oil displacement (code name SLPS, provided by Shandong Daming Fine Chemical Co., Ltd.). The concentration of the carboxyl-modified nano-oil displacement agent was 0.05%-0.3%, and the concentration of the petroleum sulfonate for oil displacement was 0.3%. The interfacial tension at 70°C was measured using a rotating drop interfacial tensiometer. The results are as follows: Figure 3 As shown.

[0233] The oil used in the experiment was dehydrated crude oil from Shengli Gudong Oilfield, with a viscosity of 102 mPa·s at 70℃.

[0234] The water used in the experiment was simulated formation water with a total mineralization of 10966 mg / L and a calcium and magnesium ion content of 334 mg / L.

[0235] from Figure 3 It can be seen that the interfacial tension between a 0.3% single petroleum sulfonate solution and Gudong crude oil can only reach 10. -1 The oil-water interfacial tension was on the order of mN / m, and the addition of carboxyl-modified nano-oil displacement agent significantly reduced the interfacial tension. The lowest interfacial tension, reaching 4 × 10⁻⁵, was observed with the addition of 0.05% carboxyl-modified nano-oil displacement agent. -3 mN / m.

[0236] Interfacial tension is closely related to the ordered arrangement of surfactants at the oil-water interface. SNP-COONa and petroleum sulfonate undergo mixed adsorption at the oil-water interface. At a concentration of 0.05%, the two molecules are arranged closely and orderly at the oil-water interface, which is most beneficial for reducing the interfacial tension. This is the result of their synergistic effect. Increasing the concentration of SNP-COONa causes SNP-COONa molecules to replace SLPS molecules at the oil-water interface, making the oil-water adsorption layer loose and disordered, which is not conducive to reducing interfacial tension. If the concentration of SNP-COONa is too low, it cannot fully fill the vacancies at the oil-water interface of petroleum sulfonate. The interfacial tension is lower than that of petroleum sulfonate alone, but it does not reach ultra-low levels.

[0237] Test Example 3 Wash Oil Rate

[0238] The carboxyl-modified nano-displacement agent obtained in Preparation Example 5 was compounded with petroleum sulfonate for oil displacement. The concentration of the nano-displacement agent was 0.05%, and the concentration of the petroleum sulfonate for oil displacement was 0.3%. Simulated formation sand and Gudong crude oil were mixed at a mass ratio of 4:1 and aged at 70°C for 7 days. The oil washing effect of the nano-displacement agent on the aged oil sand was evaluated. The test results are shown in Table 1.

[0239] Table 1 Comparison of wash-oil rates of different systems

[0240] Serial Number system Wash oil yield (%) 1 0.3% SLPS 24.8 2 0.3% SLPS + 0.05% SNP-COONa 61.4

[0241] As shown in Table 1, under the same conditions, the oil washing rate of petroleum sulfonate for oil displacement was only 24.8%. After adding 0.05% of carboxyl-modified nano-oil displacement agent, the oil washing rate of the composite system reached 61.4%, indicating that the carboxyl-modified nano-oil displacement agent has a significant synergistic effect on the oil washing performance of petroleum sulfonate.

[0242] Test Example 4 Viscosity

[0243] The carboxyl-modified nano-oil displacement agent obtained in Preparation Example 5 was compounded with a polymer (partially hydrolyzed polyacrylamide HPAM, molecular weight 22 million, provided by Shandong Baomo Biochemical Co., Ltd.). The concentration of the nano-oil displacement agent was 0.05%-0.3%, and the concentration of the polymer was 0.2%.

[0244] Viscosity was measured using an MCR302 rheometer at a test temperature of 70℃ and a shear rate of 7.34 s⁻¹. -1 The test results are shown below. Figure 4 And Table 2. From Figure 4 As shown in Table 2, within the experimental concentration range, the carboxyl-modified nano-oil displacement agent can significantly increase the viscosity of the polymer. Even with the addition of a very low concentration of 0.05% of the carboxyl-modified nano-oil displacement agent, the polymer viscosity increased from 43.2 mPa·s to 54.8%, an increase of 26.9%, demonstrating the significant thickening effect of the carboxyl-modified nano-oil displacement agent on the polymer.

[0245] Table 2. Effect of carboxyl-modified nano-oil displacement agent on polymer viscosity.

[0246] Serial Number system Viscosity (mPa·s) Viscosity retention rate (%) 1 0.2％P 43.2 — 2 0.2% P + 0.05% SNP-COONa 54.8 126.9 3 0.2% P + 0.1% SNP-COONa 62.4 144.4 4 0.2% P + 0.2% SNP-COONa 78.7 182.2 5 0.2% P + 0.3% SNP-COONa 99.2 229.6

[0247] Test Example 5: Calcium Resistance

[0248] Calcium ions of 100 mg / L and 200 mg / L were added to simulated formation water to obtain calcium-added simulated brine I and calcium-added simulated brine II. The calcium-added simulated brine was used to prepare a compound solution of the carboxyl-modified nano-oil displacement agent and polymer prepared in Example 5. The concentration of the nano-oil displacement agent was 0.05% and the concentration of the polymer was 0.2%.

[0249] Viscosity was measured using an MCR302 rheometer at a test temperature of 70℃ and a shear rate of 7.34 s⁻¹. -1 The test results are shown in Table 3. As can be seen from Table 3, the addition of 0.05% carboxyl-modified nano-oil displacement agent can significantly improve the polymer's resistance to calcium.

[0250] Table 3. Effect of carboxyl-modified nano-oil displacement agent on the anti-calcium properties of polymers.

[0251]

[0252]

[0253] Test Example 6 Oil Displacement Performance

[0254] The carboxyl-modified nano-oil displacement agent, petroleum sulfonate for oil displacement, and polymer compound system prepared in Example 5 were formulated using simulated formation water, wherein the concentration of the nano-oil displacement agent was 0.05%, the concentration of the petroleum sulfonate for oil displacement was 0.3%, and the concentration of the polymer was 0.2%.

[0255] The oil displacement test procedure is as follows:

[0256] (1) The artificial core with a gas permeability of 2000 mD was dried to constant weight, the core was saturated with water, and its pore volume was measured. The core was saturated with Gudong dehydrated crude oil, and the volume of saturated crude oil was recorded.

[0257] (2) At 70℃, water flooding was carried out at an injection rate of 0.23 mL / min until the water content of the produced fluid reached 95%. Then, 0.3 PV of the oil displacement system was injected, and water flooding was carried out again until the water content of the produced fluid reached 100%. The percentage increase in oil recovery based on water flooding was calculated. The experimental results are shown in Table 4. As can be seen from Table 4, the compound system formed by the carboxyl-modified nano-oil displacement agent prepared in Example 5 with polymer and petroleum sulfonate can increase the oil recovery by 23.8%, which is significantly better than single polymer flooding (12.7%) and polymer-surfactant binary composite flooding (16.4%).

[0258] Table 4 Results of Oil Displacement Test

[0259] Serial Number system Increase the recovery rate (%) 1 0.2％P 12.7 2 0.2% P + 0.3% SLPS 16.4 3 0.2%P+0.3%SLPS+0.05%SNP-COONa 23.8

[0260] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A carboxyl-modified nano-oil displacement agent, characterized in that, The carboxyl-modified nano-oil displacement agent consists of a nano-silica framework and functional groups attached to the nano-silica framework. The functional group is -RCOOM, where R is CH2 or C2H4, and M is one of Li, K, and Na. The structural formula of the carboxyl-modified nano-oil displacement agent is as follows:

2. The preparation method of the carboxyl-modified nano-oil displacement agent according to claim 1, characterized in that, In terms of mass, it includes the following steps: (1) Mix water and L-arginine evenly, then add tetraethyl orthosilicate, stir evenly and heat to the reaction temperature for a period of time to obtain a dispersion of hydroxyl silica nanoparticles. (2) Add an appropriate amount of 3-aminopropyltrimethoxysilane to the hydroxyl silica nanoparticle dispersion obtained in step (1), and continue to react for a period of time to obtain an amino-modified nano silica solution. Then perform a first post-treatment to obtain amino-modified nano silica particles. (3) The amino-modified nano-silica particles obtained in step (2) are dispersed in an appropriate amount of water, and then a haloacetic acid monovalent salt is added to it. After reacting for a period of time under stirring conditions and at a certain reaction temperature, an aqueous solution of the nano-oil displacement agent is obtained. Then, it is subjected to a second post-treatment to obtain the carboxyl-modified nano-oil displacement agent, wherein: The structural formula of the monovalent salt of haloacetic acid is in: X is one or more of F, Cl, Br, and I; R is CH2 or C2H4; M is one of Li, K, and Na.

3. The preparation method of the carboxyl-modified nano-oil displacement agent as described in claim 2, characterized in that, In step (1), the mass ratio of water, L-arginine, and tetraethyl orthosilicate is (60–100):0.1:(5–40), and / or In step (1), continuous stirring is performed at a speed of at least 500 rpm, preferably 500-600 rpm, and / or The reaction temperature in step (1) is at least 70°C, preferably 70–80°C, and / or The reaction time in step (1) is at least 20 hours, preferably 20 to 24 hours, and / or The water mentioned in step (1) is one of deionized water, distilled water, and ultrapure water.

4. The preparation method of the carboxyl-modified nano-oil displacement agent as described in claim 2, characterized in that, The mass ratio of the amount of 3-aminopropyltrimethoxysilane added in step (2) to the amount of L-arginine added in step (1) is 4:0.1, and / or In step (2), continuous stirring is performed at a speed of at least 500 rpm, preferably 500-600 rpm, and / or The reaction temperature in step (2) is at least 70°C, preferably 70–80°C, and / or The reaction time in step (2) is at least 20 hours, preferably 20 to 24 hours.

5. The preparation method of the carboxyl-modified nano-oil displacement agent as described in claim 2, characterized in that, The specific steps of the first post-processing in step (2) are as follows: The amino-modified nano-silica solution was centrifuged to precipitate, washed at least three times with ethanol and water respectively, and then vacuum-dried overnight at at least 25°C, preferably 25°C to 40°C. The water used for washing is deionized water or distilled water.

6. The preparation method of the carboxyl-modified nano-oil displacement agent as described in claim 2, characterized in that, In step (3), the mass ratio of amino-modified nano-silica particles, water, and haloacetic acid monovalent salt is 2:(50-80):(2-8), and / or In step (3), continuous stirring is performed at a speed of at least 500 rpm, preferably 500-600 rpm, and / or The reaction temperature in step (3) is at least 70°C, preferably 70–80°C, and / or The reaction time in step (3) is at least 20 hours, preferably 20 to 24 hours, and / or The water mentioned in step (3) is one of deionized water, distilled water, and ultrapure water.

7. The preparation method of the carboxyl-modified nano-oil displacement agent as described in claim 2, characterized in that, The specific steps of the second post-processing in step (3) are as follows: After centrifuging the aqueous solution of the nano-oil displacement agent, it is washed with water at least three times, and then vacuum dried overnight at at least 25°C, preferably 25°C to 40°C. The water used for washing is deionized water or distilled water.

8. A carboxyl-modified nano-oil displacement agent, characterized in that, It is prepared by the preparation method according to any one of claims 2-7.

9. An oil displacement system, characterized in that, Composed of the carboxyl-modified nano-oil displacement agent as described in claim 1 or 8, a polymer, a surfactant, and water, wherein: Based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.05% to 0.3%, the polymer accounts for 0.1% to 0.3%, the surfactant accounts for 0.1% to 1%, and the balance is water; Preferably, based on the total mass of the oil displacement system, the carboxyl-modified nano-oil displacement agent accounts for 0.05% to 0.2%, the polymer accounts for 0.15% to 0.25%, the surfactant accounts for 0.2% to 0.4%, and the balance is water.

10. The oil displacement system as described in claim 9, characterized in that, The polymer is one of the following: partially hydrolyzed polyacrylamide with a molecular weight of 10 million to 35 million, modified polyacrylamide with a molecular weight of 10 million to 35 million, and hydrophobic associating polymers with a molecular weight of 10 million to 35 million, and / or The surfactant is one or more of petroleum sulfonates, alkylbenzene sulfonates, olefin sulfonates, polyoxyethylene ether sulfonates, and polyoxyethylene ether carboxylates, and / or The water is either injected water or simulated formation water.

11. The application of the oil displacement system according to claim 9 or 10 as an oil displacement agent in the exploitation of high-temperature and high-salinity oil reservoirs.

12. A method for oil extraction, characterized in that, The oil displacement system described in claim 9 or 10 is injected into a high-temperature, high-salinity oil reservoir.

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