A foam modifier, its preparation method and application

Abstract

This invention provides a foam modifier, its preparation method, and its application. The foam modifier comprises a surfactant, nanoparticles, and water; the surfactant includes anionic gemini surfactants and anionic nonionic surfactants; the nanoparticles are catecholamine polymer particles. The structural formula of the anionic gemini surfactant is [insert structural formula here], and the structural formula of the anionic nonionic surfactant is R6-O-(R8-O). n -R7; The foaming agent described has good foaming properties and good stability under high-salt and high-calcium-magnesium conditions, and can be applied in high-salt reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, and more specifically, to a foam control agent, its preparation method, and its application. Background Technology

[0002] Improving and developing enhanced oil recovery technologies is crucial for ensuring stable oilfield production. my country's oilfields suffer from severe heterogeneity, and relying solely on water or gas injection for extraction often leads to fluid channeling and viscous fingering problems, resulting in low oil displacement efficiency and swept volume. Foam, with its high apparent viscosity, possesses excellent profile control characteristics, effectively blocking large volumes but not small ones, and water but not oil. It can improve the mobility ratio of the displacement phase and the oil phase in the reservoir, prevent channeling and viscous fingering during displacement, and effectively increase the sweep efficiency.

[0003] Under harsh reservoir conditions, foam stability deteriorates, making it difficult to function effectively. To improve foam stability, various types of foaming agents have been developed, such as polymer-reinforced foam and nanoparticle-reinforced foam. However, because polymers are affected by formation shear, temperature, and salinity, their viscosity may decrease significantly, leading to reduced foam stability and thus limiting their application.

[0004] Nanoparticle-reinforced foam systems enhance foam stability through particle adsorption, exhibiting good profile control and plugging effects. Chinese invention patent CN115058238A discloses a surface-modified nanoparticle high-temperature foam stabilizer. This stabilizer utilizes electrostatic interactions to adsorb short-chain alkylamines onto lithium magnesium silicate nanoparticles, increasing the hydrophobicity of the particle surface, promoting adsorption at the gas-liquid interface, and improving liquid film viscosity and interfacial viscoelasticity, thereby enhancing foam stability. However, the addition of a surface modifier increases usage costs, and during formation migration, chromatographic separation can lead to separation between the nanoparticles and the surface modifier, thus affecting foam stability.

[0005] Therefore, it is necessary to develop a foaming agent that still has good foaming properties and stability in high-salinity reservoirs. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a foam modifier, its preparation method and application.

[0007] The foam control agent provided by this invention comprises anionic gemini surfactant, anionic nonionic surfactant, nanoparticles, and water. The anionic gemini surfactant connects two hydrophilic groups and a hydrophobic chain through a spacer group, fundamentally overcoming the separation tendency caused by the charge repulsion or hydration of the ionic head group in traditional single-ionic surfactants. Simultaneously, the spacer group is a hydroxyl-substituted group, and the intermolecular hydrogen bonding interaction promotes its close arrangement on the surface, resulting in higher surface activity. The anionic nonionic surfactant has good temperature and salt resistance, and the polyether group can form hydrogen bonds with the hydroxyl groups in the anionic gemini surfactant, enhancing interfacial adsorption. The two have a synergistic effect, increasing the stability of the foam. Furthermore, this invention introduces nanoparticles, which possess certain hydrophilicity and negative charge. However, in the presence of calcium and magnesium ions, due to coordination and / or electrostatic attraction, the nanoparticles bind to divalent ions, reducing their hydrophilicity. They can then adsorb onto the gas-liquid surface, increasing the mechanical strength of the foam film and thus improving the stability of the foam under high-salt and high-calcium-magnesium conditions.

[0008] The foam modifier of the present invention has good foaming properties, and the generated foam has good stability under the conditions of mineralization of 10,000 to 200,000 mg / L and calcium and magnesium ion concentration of 500 to 20,000 mg / L. It can be used for plugging and profile control in high-salt reservoirs.

[0009] One objective of this invention is to provide a foam modifier, which comprises a surfactant, nanoparticles, and water; the surfactant comprises anionic gemini surfactants and anionic nonionic surfactants; and the nanoparticles are catecholamine polymer particles.

[0010] In a preferred embodiment of the present invention,

[0011] Based on a total weight of 100 wt% of the foam modifier, the foam modifier comprises the following components:

[0012]

[0013] In a preferred embodiment of the present invention,

[0014] The structural formula of the anionic gemini surfactant is shown in formula (I):

[0015]

[0016] In formula (I), R1 and R2 are each independently selected from one of C2 to C22 hydrocarbon groups or substituted hydrocarbon groups, wherein the substituted hydrocarbon group is one of ester group, amide group, or hydroxyl group;

[0017] R3 is one of the C1 to C10 hydroxyl-substituted hydrocarbon groups;

[0018] R4 and R5 are each independently selected from one of C1 to C8 alkylene groups or substituted alkylene groups, wherein the substituent in the substituted alkylene group is one of ester group, amide group, or hydroxyl group;

[0019] X- is an anion or an anionic group; and / or,

[0020] The structural formula of the anionic nonionic surfactant is shown in formula (II):

[0021] R6-O-(R8-O) n -R7 type (Ⅱ);

[0022] In formula (II), R6 is C6~C 24 R7 is one of the hydrocarbon groups; R8 is one of the alkylene carboxylate, alkylene sulfonate, and hydroxyalkylene sulfonate; R9 is one of the C2-C4 straight-chain or branched alkylene groups; n is an integer from 1 to 40.

[0023] In a preferred embodiment of the present invention,

[0024] In formula (I),

[0025] R1 and R2 are each independently selected from a hydrocarbon group of C4 to C20; and / or,

[0026] R3 is one of the hydroxyl-substituted alkylene groups from C3 to C6; and / or,

[0027] R4 and R5 are each independently selected from one of C1 to C5 alkylene or hydroxylated alkylene groups; and / or,

[0028] X- is either COO- or SO3-;

[0029] Preferably, R1 and R2 are each independently selected from one of the alkyl or alkenyl groups from C4 to C20, such as alkyl or alkenyl groups from C4, C6, C8, C10, C12, C14, C16, C18, or C20, or any combination of two of the above values, for example, alkyl or alkenyl groups from C10 to C16; and / or,

[0030] R3 is selected from one of the C3-C4 hydroxy-substituted alkylene groups; and / or,

[0031] R4 and R5 are each independently selected from one of C1-C4 alkylene or hydroxylated alkylene groups; and / or,

[0032] In formula (II),

[0033] R6 is one of the alkyl groups from C8 to C20, such as alkyl groups of C8, C10, C12, C14, C16, C18, or C20, or any two of the above values, for example, alkyl groups of C12 to C18; and / or,

[0034] R7 is one of C1-C4 alkylene carboxylates, alkylene sulfonates, and hydroxyalkylene sulfonates; and / or,

[0035] R8 is ethylene; and / or,

[0036] n is an integer from 1 to 30, such as 1, 5, 10, 15, 20, 25, 30, or any two of the above numbers, for example, 5 to 10.

[0037] In a preferred embodiment of the present invention,

[0038] The nanoparticles are at least one of dopamine self-polymer particles, norepinephrine self-polymer particles, L-DOPA self-polymer particles, dralidopa self-polymer particles, and α-methyldopa self-polymer particles, preferably dopamine self-polymer particles; and / or,

[0039] The surface of the nanoparticles has a wetting angle with water of 10–60°, preferably 25–50°; and / or,

[0040] The average particle size of the nanoparticles is 50–500 nm, preferably 70–300 nm; and / or,

[0041] The nanoparticles have a negatively charged surface; and / or,

[0042] The total mineralization of the water is 10,000–200,000 mg / L; and / or,

[0043] The concentration of calcium and magnesium ions in the water is 500–20000 mg / L;

[0044] More preferably,

[0045] The preparation method of the nanoparticles includes: dissolving catecholamine compounds in an alkaline aqueous solution, stirring and reacting, followed by centrifugation, washing, and drying to obtain the nanoparticles;

[0046] More preferably,

[0047] The catecholamine compound is at least one selected from dopamine hydrochloride, norepinephrine, L-DOPA, droxidopa, and α-methyldopa; and / or,

[0048] The concentration of the catecholamine compound in water is 0.25–1 mg / mL; and / or,

[0049] The pH of the alkaline aqueous solution is 8–10; and / or,

[0050] The alkaline aqueous solution is a Tris-HCl buffer solution, which is prepared with tris(hydroxymethyl)aminomethane (Tris) and hydrochloric acid; and / or,

[0051] The reaction temperature is 20–30°C; and / or,

[0052] The reaction time is 6 to 18 hours.

[0053] In a preferred embodiment of the present invention,

[0054] The preparation method of the anionic gemini surfactant includes: reacting components including primary amines or their derivatives, halosulfonates or halocarboxylate compounds, and dihaloalcohols to obtain the anionic gemini surfactant;

[0055] Preferably, the preparation method of the anionic gemini surfactant includes the following steps:

[0056] (1) Add a primary amine or its derivative, a halosulfonate compound or a halocarboxylate compound to a solvent and heat to react;

[0057] (2) Add a dihalool to the system after the reaction in step (1) and continue the reaction. The product is then post-treated to obtain the anionic gemini surfactant.

[0058] In a preferred embodiment of the present invention,

[0059] The primary amine or its derivative is at least one of primary amines or their derivatives having 2 to 22 carbon atoms, preferably at least one of aliphatic primary amines having 4 to 20 carbon atoms, more preferably at least one of n-decylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine; and / or,

[0060] The halosulfonate compound is at least one of a haloalkylsulfonate or its derivative having 1 to 8 carbon atoms, preferably at least one of a haloalkylsulfonate or halohydroxyalkylsulfonate having 1 to 4 carbon atoms, more preferably at least one of sodium 2-chloroethylsulfonate, sodium 2-bromoethylsulfonate, sodium 3-chloro-2-hydroxypropanesulfonate, and sodium 4-chloro-1-hydroxy-butanesulfonate; and / or,

[0061] The halocarboxylate compound is at least one of a haloalkylcarboxylate or its derivative having 2 to 9 carbon atoms, preferably at least one of a haloalkylcarboxylate or a halohydroxyalkylcarboxylate having 2 to 5 carbon atoms, more preferably at least one of sodium chloroacetate, sodium bromoacetate, sodium β-chloropropionate, and sodium β-bromopropionate; and / or,

[0062] The dihaloalcohol is a dihaloalcohol with 1 to 10 carbon atoms, preferably a dihaloalcohol with 3 to 4 carbon atoms, more preferably at least one selected from 1,3-dichloro-2-propanol, 1,3-dibromo-2-propanol, 1,4-dichloro-2-butanol, 1,4-dibromo-2-butanol, 1,4-dichloro-2,3-butanediol, and 1,4-dibromo-2,3-butanediol; and / or,

[0063] The molar ratio of the primary amine or its derivative, halosulfonate compound or halocarboxylate compound, and dihaloalcohol is 1:(1-1.5):(0.5-0.75), preferably 1:(1-1.2):(0.5-0.6).

[0064] In a preferred embodiment of the present invention,

[0065] In step (1),

[0066] The solvent is a mixture of water and an organic solvent, wherein the organic solvent is preferably at least one of alcohols, more preferably at least one of ethanol, isopropanol, and ethylene glycol; and / or,

[0067] The pH of the reaction system is 8–10; and / or,

[0068] The reaction temperature is 70–90℃; and / or,

[0069] The reaction time is 6–16 hours; and / or,

[0070] In step (2),

[0071] The reaction temperature is 70–90℃; and / or,

[0072] The reaction time is 6–16 hours; and / or,

[0073] The post-processing includes concentration, washing, and recrystallization.

[0074] The concentration, washing, and recrystallization in step (2) can all be carried out using the commonly used heating concentration, solvent washing, and recrystallization processes in the art. For example, most of the solvent can be removed from the solution after the reaction by rotary evaporation, followed by washing with an organic solvent (e.g., acetone) and recrystallization with a solvent (e.g., acetone / water) to obtain the anionic gemini surfactant.

[0075] Preferably, the anionic nonionic surfactant can be obtained by the following preparation method:

[0076] Fatty alcohol polyoxyethylene ether (lauryl alcohol polyoxyethylene ether, tetradecyl alcohol polyoxyethylene ether, hexadecyl alcohol polyoxyethylene ether, or octadecyl alcohol polyoxyethylene ether) and NaOH are added to a reactor and reacted at 65°C for 2–4 hours. Then, a sulfonating agent (sodium 3-chloro-2-hydroxypropanesulfonate or sodium 2-chloroethylsulfonate) or a carboxylating agent sodium chloroacetate is added, and the temperature is raised to 80–90°C for 6–10 hours. The molar ratio of fatty alcohol polyoxyethylene ether:NaOH:sulfonating or carboxylating agent is 1:(1.2–1.8):(1.8–2.2). After acidification and washing with water, oil-water separation is performed, and the oil phase is further alkalized to obtain anionic nonionic surfactant.

[0077] A second objective of this invention is to provide a method for preparing a foam control agent, comprising:

[0078] The components, including the surfactant, are dissolved in water, and then the nanoparticles are added and dispersed to obtain a foam modifier.

[0079] Preferably,

[0080] Disperse the nanoparticles uniformly; and / or,

[0081] The dispersion method is ultrasonic dispersion.

[0082] The third objective of this invention is to provide an application of a foam-based modifier in high-salinity reservoirs, particularly its application in modifier applications in high-salinity reservoirs.

[0083] Compared with the prior art, the present invention has the following beneficial effects:

[0084] The foam modifier provided by this invention contains anionic gemini surfactants that overcome the separation tendency caused by the charge repulsion or hydration of ionic head groups. The spacer group is a hydroxyl-substituted group, which can form intramolecular or intermolecular hydrogen bonds with anionic nonionic surfactants, thereby increasing the adsorption amount on the gas-liquid surface and improving the stability of the foam.

[0085] The foam control agent provided by this invention comprises nanoparticles that possess certain hydrophilicity and negative charge. After adsorption by calcium and magnesium ions in the reservoir environment, their hydrophilicity is weakened, allowing them to adsorb onto the gas-liquid surface, increasing the mechanical strength of the foam film and improving its stability under high-salt, high-calcium-magnesium conditions. This in-situ hydrophobication method is simple, convenient to operate, and has good application prospects.

[0086] The foam-based flood control agent provided by this invention utilizes the synergistic effect of surfactants and nanoparticles to form foams that are resistant to calcium and magnesium, making it suitable for flood control applications in high-salt reservoirs. Detailed Implementation

[0087] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0088] The raw materials used in the examples and comparative examples were all commercially available raw materials or prepared according to methods described in the prior art.

[0089] Test method:

[0090] Nanoparticle size and potential testing: The size and potential of the nanoparticles were measured using a Malvern dynamic light scattering particle size analyzer. Specifically, a nanoparticle dispersion was taken, placed in a quartz cuvette or a Zeta potential sample cell, and equilibrated at 25°C for 3 minutes before measurement. The measuring instrument used was a Malvern Nano ZS90 dynamic light scattering particle size analyzer.

[0091] Wettability test: The test method was in accordance with the literature (Daily Chemical Industry. 2020, 50(03): 182-187), specifically: the sample was compressed into tablets using a powder tablet press, and the contact angle of ultrapure water on the sample tablet was measured using the pendant drop method. The contact angle measuring instrument used was JC2000D.

[0092] Foam performance testing: Foam performance was tested using the Waring-Blender method. 100 mL of foam modifier was added to a Waring stirrer and stirred at 3000 rpm for 3 minutes under a nitrogen atmosphere to induce foaming. After stirring, the foam was poured into a 1000 mL graduated cylinder, and the initial volume (foaming volume) and half-life of the eluent were recorded at room temperature and pressure.

[0093] Blocking performance test:

[0094] The sealing performance of the foam system was evaluated using the drag factor measured by core displacement experiments. The permeability of the sand-filled tube was 2800 md, the gas-liquid ratio was 1:1, and the total injection rate was 1 mL / min. First, brine and nitrogen were injected simultaneously, and the equilibrium pressure at both ends was recorded. Then, foam displacement agent and nitrogen were injected simultaneously, and the equilibrium pressure at both ends was recorded. The ratio of the latter to the former is the drag factor.

[0095] Example 1

[0096] (1) Preparation of anionic gemini surfactants

[0097] The anionic gemini surfactant 14-S(OH)-3(OH)-S(OH)-14 has the following molecular structure:

[0098]

[0099] Its preparation method:

[0100] 1 mol of tetradecylamine and 1.1 mol of sodium 3-chloro-2-hydroxypropanesulfonate were added to a reaction vessel, along with 200 mL of an ethanol / water mixture (v:v 1:1). The pH was adjusted to 9, and the reaction was carried out at 80°C for 8 hours. Then, 0.55 mol of 1,3-dibromo-2-propanol was added, and the reaction was continued for another 8 hours. Most of the solvent was removed by rotary evaporation, and acetone was added and stirred. The mixture was cooled to 0°C and maintained at that temperature for 2 hours. The solid was purified by recrystallization from acetone / water to obtain the product.

[0101] (2) Preparation of nanoparticles

[0102] Dopamine hydrochloride was added to Tris-HCl buffer (pH 8.5) to achieve a concentration of 0.8 mg / mL. The mixture was stirred continuously at room temperature for 8 hours, collected by centrifugation, washed three times with water, and vacuum-dried at 60 °C to produce dopamine self-polymerized nanoparticles. The resulting nanoparticles had an average size of 263 nm, a zeta potential of -13 mV, and a water contact angle of 48°.

[0103] (3) Preparation of sodium lauryl polyoxyethylene ether acetate, an anionic nonionic surfactant

[0104] Lauryl alcohol polyoxyethylene ether (polyether number 5-10) and NaOH were added to a reactor and reacted at 65°C for 3 hours. Then, sodium chloroacetate was added and the temperature was raised to 85°C for 8 hours. The molar ratio of lauryl alcohol polyoxyethylene ether:NaOH:sodium chloroacetate was 1:1.5:2. After acidification and washing with water, oil-water separation was performed, and the oil phase was further alkalized to obtain sodium lauryl alcohol polyoxyethylene ether acetate.

[0105] (4) Preparation of foam control agent

[0106] The components, including 14-S(OH)-3(OH)-S(OH)-14 and the anionic nonionic surfactant sodium lauryl polyoxyethylene ether acetate, were dissolved in a solution with a total salinity of 100,000 mg / L and Ca... 2+ +Mg 2+ Nanoparticles were added to a 1000 mg / L saline solution and ultrasonically dispersed to obtain a foam control agent. The concentrations of the anionic gemini surfactant, the anionic nonionic surfactant, and the nanoparticles were 0.06 wt%, 0.15 wt%, and 0.5 wt%, respectively.

[0107] Example 2

[0108] (1) Preparation of anionic gemini surfactants

[0109] The anionic gemini surfactant 16-C-3(OH)-C-16 has the following molecular structure:

[0110]

[0111] Its preparation method:

[0112] 1 mol of hexadecylamine and 1.2 mol of sodium chloroacetate were added to a reaction vessel, followed by 200 mL of an ethanol / water mixture (v:v 1:1). The pH was adjusted to 9, and the reaction was carried out at 80°C for 8 hours. Then, 0.6 mol of 1,3-dichloro-2-propanol was added, and the reaction was continued for another 8 hours. Most of the solvent was removed by rotary evaporation, and acetone was added and stirred. The mixture was cooled to 0°C and maintained at that temperature for 2 hours. The solid was purified by recrystallization from acetone / water to obtain the product.

[0113] (2) Preparation of nanoparticles

[0114] Dopamine hydrochloride was added to Tris-HCl buffer (pH 8.0) to achieve a concentration of 0.3 mg / mL. The mixture was stirred continuously at room temperature for 16 h, collected by centrifugation, washed three times with water, and vacuum-dried at 60 °C to produce dopamine self-polymerized nanoparticles. The resulting nanoparticles had an average size of 151 nm, a zeta potential of -19 mV, and a water contact angle of 41°.

[0115] (3) Preparation of the anionic nonionic surfactant sodium octadecyl alcohol polyoxyethylene ether ethanesulfonate

[0116] Octadecyl alcohol polyoxyethylene ether (polyether number 5-10) and NaOH were added to a reactor and reacted at 65°C for 3 hours. Then, sodium 2-chloroethyl sulfonate was added and the temperature was raised to 85°C for 8 hours. The molar ratio of octadecyl alcohol polyoxyethylene ether:NaOH:sodium 2-chloroethyl sulfonate was 1:1.5:2. After acidification and washing with water, oil-water separation was performed, and the oil phase was further alkalized to obtain sodium octadecyl alcohol polyoxyethylene ether ethanesulfonate.

[0117] (4) Preparation of foam control agent

[0118] The components, including 16-C-3(OH)-C-16 and the anionic nonionic surfactant sodium octadecyl alcohol polyoxyethylene ether ethanesulfonate, were dissolved in a solution with a total salinity of 100,000 mg / L and Ca... 2+ +Mg 2+ Nanoparticles were added to a 1000 mg / L saline solution and ultrasonically dispersed to obtain a foam control agent. The concentrations of the anionic gemini surfactant, the anionic nonionic surfactant, and the nanoparticles were 0.18 wt%, 0.12 wt%, and 0.3 wt%, respectively.

[0119] Example 3

[0120] (1) Preparation of anionic gemini surfactants

[0121] The anionic gemini surfactant 10-S-4(OH)-S-10 has the following molecular structure:

[0122]

[0123] Its preparation method:

[0124] 1 mol of n-decylamine and 1 mol of sodium 2-chloroethylsulfonate were added to a reaction vessel, along with 200 mL of an ethanol / water mixture (v:v1:1). The pH was adjusted to 9, and the reaction was carried out at 80°C for 8 hours. Then, 0.5 mol of 1,4-dibromo-2-butanol was added, and the reaction was continued for another 8 hours. Most of the solvent was removed by rotary evaporation, and acetone was added and stirred. The mixture was cooled to 0°C and maintained at that temperature for 2 hours. The solid was purified by recrystallization from acetone / water to obtain the product.

[0125] (2) Preparation of the anionic nonionic surfactant sodium hexadecyl alcohol polyoxyethylene ether hydroxypropanesulfonate

[0126] Cetyl alcohol polyoxyethylene ether (polyether number 5-10) and NaOH were added to a reactor and reacted at 65°C for 3 hours. Then, sodium 3-chloro-2-hydroxysulfonate was added and the temperature was raised to 85°C for 8 hours. The molar ratio of cetyl alcohol polyoxyethylene ether:NaOH:sodium 3-chloro-2-hydroxysulfonate was 1:1.5:2. After acidification and washing with water, oil-water separation was performed, and the oil phase was further alkalized to obtain sodium cetyl alcohol polyoxyethylene ether hydroxypropanesulfonate.

[0127] (3) Preparation of foam modifier

[0128] The nanoparticles were the dopamine self-polymer particles prepared in Example 1. The components including 10-S-4(OH)-S-10 and the anionic nonionic surfactant sodium hexadecyl alcohol polyoxyethylene ether hydroxypropanesulfonate were dissolved in a solution with a total salinity of 100,000 mg / L and Ca... 2+ +Mg 2+ Nanoparticles were added to a 1000 mg / L saline solution and ultrasonically dispersed to obtain a foam control agent. The concentrations of the anionic gemini surfactant, the anionic nonionic surfactant, and the nanoparticles were 0.05 wt%, 0.35 wt%, and 0.1 wt%, respectively.

[0129] Comparative Example 1

[0130] The difference from Example 2 is that the foam modifier does not contain anionic gemini surfactants, and the concentration of the anionic nonionic surfactant sodium octadecyl alcohol polyoxyethylene ether ethanesulfonate is 0.3 wt%.

[0131] Except for the differences mentioned above, all other conditions in Comparative Example 1 were the same as in Example 2, resulting in a foam modifier.

[0132] Comparative Example 2

[0133] The difference from Example 2 is that the foam modifier does not contain anionic nonionic surfactants, and the concentration of the anionic gemini surfactant 16-C-3(OH)-C-16 is 0.3wt%.

[0134] Except for the differences mentioned above, all other conditions in Comparative Example 2 were the same as in Example 2, and a foam modifier was obtained.

[0135] Comparative Example 3

[0136] The difference from Example 2 is that the water used in the foam control agent is deionized water;

[0137] Except for the differences mentioned above, all other conditions in Comparative Example 3 were the same as in Example 2, and a foam modifier was obtained.

[0138] Comparative Example 4

[0139] The difference from Example 3 is that the anionic gemini surfactant in the foam modifier is replaced by a conventional foaming agent, sodium dodecylbenzenesulfonate.

[0140] Apart from the differences mentioned above, all other conditions in Comparative Example 4 were the same as in Example 3, resulting in a foam modifier.

[0141] Comparative Example 5

[0142] The difference from Example 3 is that the anionic nonionic surfactant in the foam modifier is replaced by a conventional foaming agent, sodium α-olefin sulfonate, by mass.

[0143] Apart from the differences mentioned above, all other conditions in Comparative Example 5 were the same as in Example 3, resulting in a foam modifier.

[0144] Comparative Example 6

[0145] The difference from Example 3 is that nano-calcium carbonate of equal mass is used to replace the nanoparticles in the foam modifier;

[0146] Except for the differences mentioned above, all other conditions in Comparative Example 4 were the same as in Example 3, resulting in a foam modifier / displacement agent. The foaming properties of the foam modifier / displacement agent in Test Example 1 were also tested.

[0147] The foam properties were tested using the Waring-Blender method. 100 mL of foam modifier was added to a Waring stirrer and stirred at 3000 rpm for 3 minutes under a nitrogen atmosphere to induce foaming. After stirring, the foam was poured into a 1000 mL graduated cylinder, and the initial volume (foaming volume) and half-life of the eluent were recorded at room temperature and pressure. The results of each example and comparative example are shown in Table 1.

[0148] Test Example 2: Plugging Performance of Foam Modifier

[0149] The sealing performance of the foam system was evaluated using the drag factor measured by core displacement experiments. The permeability of the sand-filled tube was 2800 md, the gas-liquid ratio was 1:1, and the total injection rate was 1 mL / min. First, brine and nitrogen were injected simultaneously, and the equilibrium pressure at both ends was recorded. Then, foam displacement agent and nitrogen were injected simultaneously, and the equilibrium pressure at both ends was recorded. The ratio of the latter to the former is the drag factor. The results of each example and comparative example are shown in Table 1.

[0150] Table 1. Foaming and plugging properties of the foam modifiers prepared in Examples 1-3 and Comparative Examples 1-6.

[0151] serial number foaming volume / mL half-life of the precipitate / min Resistance factor Example 1 577 26 189.2 Example 2 594 22 176.5 Example 3 608 20 167.3 Comparative Example 1 522 17 134.8 Comparative Example 2 325 9 90.2 Comparative Example 3 600 15 123.6 Comparative Example 4 581 14 112.9 Comparative Example 5 216 5 61.7 Comparative Example 6 595 18 128.4

[0152] Foam volume characterizes foaming ability; a larger volume indicates easier foam formation. Generally, a larger foam volume corresponds to a longer half-life, indicating better foaming ability and stability.

[0153] As shown in Table 1, Example 2 exhibits better foaming properties and foam stability compared to Comparative Examples 1 and 2, as well as better sealing performance. This demonstrates that the combination of anionic gemini surfactant and anionic nonionic surfactant is superior to using them alone, and that the combined use of these two surfactants has a synergistic effect.

[0154] Comparative Example 3 has a foaming ability comparable to Example 2, but its foam stability is worse. This is because the nanoparticles are hydrophilic in deionized water and cannot be adsorbed at the gas-liquid interface to stabilize the foam.

[0155] Comparative Example 4 used commonly used sodium dodecylbenzene sulfonate instead of the anionic gemini surfactant in Example 3. The foaming properties were comparable, but the foam stability and plugging performance both decreased. Comparative Example 5 used sodium α-olefin sulfonate instead of the anionic nonionic surfactant in Example 3, resulting in a significant decrease in foaming properties, foam stability, and plugging performance. Comparative Examples 4 and 5 also demonstrate the synergistic effect of the two surfactant combinations in this invention; replacing one with a commonly used anionic surfactant resulted in varying degrees of performance degradation.

[0156] The foam performance of the sample in Comparative Example 6 was comparable to that in Example 3, indicating that the nano-calcium carbonate stabilized the foam by adsorbing onto the gas-liquid interface through interaction with the surfactant. However, during the displacement process, chromatographic separation occurred, and the nano-calcium carbonate separated from the surfactant, failing to continue stabilizing the foam. This resulted in a decrease in the resistance factor and poor sealing performance.

[0157] The foam modifiers prepared in Examples 1-3 exhibit the synergistic effect of two surfactants and nanoparticles, resulting in foams that are resistant to calcium and magnesium, with good foaming properties, foam stability, and plugging performance, making them suitable for modifier applications in high-salt reservoirs.

Claims

1. A foam modifier, comprising a surfactant, nanoparticles, and water; wherein the surfactant comprises anionic gemini surfactants and anionic nonionic surfactants; and the nanoparticles are catecholamine polymer particles.

2. The foam control agent as described in claim 1, characterized in that: Based on a total weight of 100 wt% of the foam modifier, the foam modifier comprises the following components: The anionic gemini surfactant is present at 0.01–0.3 wt%; preferably 0.05–0.2 wt%. The anionic nonionic surfactant is present in an amount of 0.01–0.5 wt%; preferably 0.1–0.4 wt%. Nanoparticles: 0.1–1 wt%; preferably 0.1–0.5 wt%. The remainder is water.

3. The foam control agent as described in claim 1, characterized in that: The structural formula of the anionic gemini surfactant is shown in formula (I): In formula (I), R1 and R2 are each independently selected from one of C2 to C22 hydrocarbon groups or substituted hydrocarbon groups, wherein the substituted hydrocarbon group is one of ester group, amide group, or hydroxyl group; R3 is one of the C1 to C10 hydroxyl-substituted hydrocarbon groups; R4 and R5 are each independently selected from one of C1 to C8 alkylene groups or substituted alkylene groups, wherein the substituent in the substituted alkylene group is one of ester group, amide group, or hydroxyl group; X- is an anion or an anionic group; and / or, The structural formula of the anionic nonionic surfactant is shown in formula (II): R6-O-(R8-O) n -R7 type (Ⅱ); In formula (II), R6 is one of the hydrocarbon groups from C6 to C24; R7 is one of the alkylene carboxylate, alkylene sulfonate, and hydroxyalkylene sulfonate; R8 is one of the straight-chain or branched alkylene groups from C2 to C4; and n is an integer from 1 to 40.

4. The foam control agent as described in claim 3, characterized in that: In formula (I), R1 and R2 are each independently selected from a hydrocarbon group of C4 to C20; and / or, R3 is one of the hydroxyl-substituted alkylene groups from C3 to C6; and / or, R4 and R5 are each independently selected from one of C1 to C5 alkylene or hydroxylated alkylene groups; and / or, X- is either COO- or SO3-; Preferably, R1 and R2 are each independently selected from one of alkyl or alkenyl groups from C4 to C20; and / or, R3 is selected from one of the C3-C4 hydroxy-substituted alkylene groups; and / or, R4 and R5 are each independently selected from one of C1-C4 alkylene or hydroxylated alkylene groups; and / or, In formula (II), R6 is one of the alkyl groups from C8 to C20; and / or, R7 is one of C1-C4 alkylene carboxylates, alkylene sulfonates, and hydroxyalkylene sulfonates; and / or, R8 is ethylene; and / or, n is an integer from 1 to 30.

5. The foam control agent as described in claim 1, characterized in that: The nanoparticles are at least one of dopamine self-polymer particles, norepinephrine self-polymer particles, L-DOPA self-polymer particles, dralidopa self-polymer particles, and α-methyldopa self-polymer particles, preferably dopamine self-polymer particles; and / or, The surface of the nanoparticles has a water wetting angle of 10–60°, preferably 25–50°; and / or, The average particle size of the nanoparticles is 50–500 nm, preferably 70–300 nm; and / or, The nanoparticles have a negatively charged surface; and / or, The total mineralization of the water is 10,000–200,000 mg / L; and / or, The concentration of calcium and magnesium ions in the water is 500–20000 mg / L; More preferably, The preparation method of the nanoparticles includes: dissolving a catecholamine compound in an alkaline aqueous solution, stirring and reacting, followed by centrifugation, washing, and drying to obtain the nanoparticles; More preferably, The catecholamine compound is at least one selected from dopamine hydrochloride, norepinephrine, L-DOPA, droxidopa, and α-methyldopa; and / or, The concentration of the catecholamine compound in water is 0.25–1 mg / mL; and / or, The pH of the alkaline aqueous solution is 8–10; and / or, The alkaline aqueous solution is a Tris-HCl buffer solution; and / or, The reaction temperature is 20–30°C; and / or, The reaction time is 6 to 18 hours.

6. The foam control agent as described in claim 1, characterized in that: The preparation method of the anionic gemini surfactant includes: reacting components including primary amines or their derivatives, halosulfonates or halocarboxylate compounds, and dihaloalcohols to obtain the anionic gemini surfactant; Preferably, the preparation method of the anionic gemini surfactant includes the following steps: (1) Add a primary amine or its derivative, a halosulfonate compound or a halocarboxylate compound to a solvent and heat to react; (2) Add a dihalool to the system after the reaction in step (1) and continue the reaction. The product is then post-treated to obtain the anionic gemini surfactant.

7. The foam control agent as described in claim 6, characterized in that: The primary amine or its derivative is at least one of primary amines or their derivatives having 2 to 22 carbon atoms, preferably at least one of aliphatic primary amines having 4 to 20 carbon atoms, more preferably at least one of n-decylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine; and / or, The halosulfonate compound is at least one of a haloalkylsulfonate or its derivative having 1 to 8 carbon atoms, preferably at least one of a haloalkylsulfonate or halohydroxyalkylsulfonate having 1 to 4 carbon atoms, more preferably at least one of sodium 2-chloroethylsulfonate, sodium 2-bromoethylsulfonate, sodium 3-chloro-2-hydroxypropanesulfonate, and sodium 4-chloro-1-hydroxy-butanesulfonate; and / or, The halocarboxylate compound is at least one of a haloalkylcarboxylate or its derivative having 2 to 9 carbon atoms, preferably at least one of a haloalkylcarboxylate or a halohydroxyalkylcarboxylate having 2 to 5 carbon atoms, more preferably at least one of sodium chloroacetate, sodium bromoacetate, sodium β-chloropropionate, and sodium β-bromopropionate; and / or, The dihaloalcohol is a dihaloalcohol with 1 to 10 carbon atoms, preferably a dihaloalcohol with 3 to 4 carbon atoms, more preferably at least one selected from 1,3-dichloro-2-propanol, 1,3-dibromo-2-propanol, 1,4-dichloro-2-butanol, 1,4-dibromo-2-butanol, 1,4-dichloro-2,3-butanediol, and 1,4-dibromo-2,3-butanediol; and / or, The molar ratio of the primary amine or its derivative, halosulfonate compound or halocarboxylate compound, and dihaloalcohol is 1:(1-1.5):(0.5-0.75), preferably 1:(1-1.2):(0.5-0.6).

8. The foam control agent as described in claim 6, characterized in that: In step (1), The solvent is a mixture of water and an organic solvent, wherein the organic solvent is preferably at least one of alcohols, more preferably at least one of ethanol, isopropanol, and ethylene glycol; and / or, The pH of the reaction system is 8–10; and / or, The reaction temperature is 70–90℃; and / or, The reaction time is 6–16 hours; and / or, In step (2), The reaction temperature is 70–90℃; and / or, The reaction time is 6–16 hours; and / or, The post-processing includes concentration, washing, and recrystallization.

9. A method for preparing a foam control agent as described in any one of claims 1 to 8, comprising: The components, including the surfactant, are dissolved in water, and then the nanoparticles are added and dispersed to obtain a foam modifier. Preferably, Disperse the nanoparticles uniformly; and / or, The dispersion method is ultrasonic dispersion.

10. The application of a foam modifier as described in any one of claims 1 to 8 or a foam modifier prepared by the method described in claim 9 in high-salinity reservoirs, particularly in modifier application in high-salinity reservoirs.

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