Low-condensation-point multifunctional fracturing fluid aqua and preparation method thereof

Abstract

The invention relates to the technical field of fracturing fluid aqua, in particular to a low-condensation-point multifunctional fracturing fluid aqua and a preparation method thereof, the low-condensation-point multifunctional fracturing fluid aqua is formed by mixing a dispersing agent, a betaine composition, a cationic composition and water in proportion, according to the invention, the crystal structure between water molecules is broken through the surfactant (betaine composition) which forms multiple hydrogen bonds and high-energy chemical bonds with the water molecules, and the surfactant (cationic composition) with the high-energy chemical bonds enables the system to release more heat when the temperature is reduced by 1 DEG C; the raw materials are mixed to obtain the low-condensation-point multifunctional fracturing fluid aqua with excellent performance, the condensation point of the low-condensation-point multifunctional fracturing fluid aqua is-52 DEG C, the low-condensation-point multifunctional fracturing fluid aqua has the characteristics of discharge aiding, foaming and viscosity stability, and the problems of crystallization and incompatibility of most existing oil and gas well fracturing fluid aqua in winter are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of fracturing fluid aqueous agents, and is a low-freezing-point multifunctional fracturing fluid aqueous agent and a preparation method thereof. Background Art

[0002] At present, most of the domestic oil and gas field development has entered the middle and late stages, and the task of increasing production and ensuring supply in winter is becoming more and more urgent. The winter temperature in Sulige Gas Field, Xinjiang Oilfield and other places can reach as low as -35°C, and the existing conventional fracturing fluid aqueous agents are basically all frozen. Due to the extremely cold weather, some areas are forced to stop fracturing construction.

[0003] The existing fracturing fluid antifreeze agents on the market are mostly added with antifreeze agents such as sodium chloride and ethylene glycol. They are not only expensive, but also have average antifreeze performance. Generally, when the temperature is lower than -25°C, the existing fracturing fluid antifreeze agents begin to freeze and lose fluidity, and must rely on steam boilers for thawing operations. On the other hand, with the implementation of the low-cost development strategy of the oil and gas industry, the compatibility of fracturing chemical materials has become increasingly different. When different fracturing fluid antifreeze agents are used for fracturing construction, incompatibility phenomena such as flocs and precipitation occur. Summary of the invention

[0004] The present invention provides a low-freezing-point multifunctional fracturing fluid aqueous agent and a preparation method thereof, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of weak antifreeze performance and poor compatibility of the existing fracturing fluid antifreeze aqueous agents.

[0005] One of the technical solutions of the present invention is achieved through the following measures: a low-freezing-point multifunctional fracturing fluid aqueous agent, the raw materials of which include 30% to 40% dispersant, 15% to 25% betaine composition, 25% to 35% cationic composition and the balance water in weight percentage.

[0006] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The above-mentioned dispersant is mixed with oligomer polyol, polycarboxylic acid antifreeze and low-carbon alcohol in a mass ratio of 1:1:(9.5 to 10.5), the oligomer polyol is one of polyethylene glycol, low-branching polyester polyol and polyester diol, and the low-carbon alcohol is one of methanol, ethylene glycol, glycerol and isopropanol.

[0007] Among the above dispersants, the polycarboxylic acid antifreeze is obtained by the following method: allyl polyoxyethylene ether is added to deionized water under stirring and mixed, and then 10% hydrogen peroxide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and 10% initiator solution are sequentially added dropwise to react to obtain a reaction product, and after adjusting the pH value of the reaction product, a polycarboxylic acid antifreeze with a mass concentration of 30% is obtained.

[0008] In the preparation method of the polycarboxylic acid antifreeze, the mass ratio of deionized water to allyl polyoxyethylene ether is 2:5, and the molar ratio of allyl polyoxyethylene ether, acrylic acid, and 2-acrylamide-2-methylpropane sulfonic acid is 1:2:0.6.

[0009] In the preparation method of the polycarboxylic acid antifreeze agent, the added amount of 10% hydrogen peroxide and 10% initiator solution is 3.0% to 3.5% of the total mass of allyl polyoxyethylene ether, and the initiator is sodium bisulfite.

[0010] In the preparation method of the polycarboxylic acid antifreeze, the dropping time is 1 to 2 hours, the reaction time is 2 hours, and the pH value of the reaction product is adjusted to 7.

[0011] The betaine composition is prepared by mixing lauramidopropyl hydroxysulfobetaine and cocoamidopropyl betaine in a mass ratio of 5:1.

[0012] The cationic composition is formed by mixing a gemini quaternary ammonium salt surfactant, a small cationic surfactant and an inorganic salt in a mass ratio of 6:1:1, the small cationic surfactant is one or more of dimethyldiallylammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride and hexadecyltrimethylammonium chloride, and the inorganic salt is potassium chloride.

[0013] In the above cationic composition, the Gemini quaternary ammonium salt surfactant is a quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane. The 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane is obtained by the following method: S1, add 480mmol of dodecane bromide and 2.08mol of diethanolamine to anhydrous ethanol to react under reflux for 10h to 12h to obtain product 1, cool product 1 to room temperature, add 0.7mol of sodium hydroxide to product 1 and continue to react for 1.0h to 1.5h to obtain product 2; S2, subjecting the product 2 to rotary evaporation, ether dissolution and suction filtration in sequence to obtain a filtrate, and subjecting the filtrate to rotary evaporation and reduced pressure distillation to obtain dodecyldiethanolamine; S3, adding 1,3-dibromoisopropanol and anhydrous ethanol to dodecyldiethanolamine in sequence and performing reflux reaction for 70 to 72 hours to obtain product three, cooling product three to room temperature, and then performing rotary evaporation to obtain a residue; S4, dissolving the residue in anhydrous ethanol, recrystallizing with a mixed solvent and drying in sequence to obtain 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane.

[0014] In the above step S3, the mass ratio of dodecyldiethanolamine to 1,3-dibromoisopropanol is 13:1.

[0015] In the above step S1, the reflux reaction temperature is 55°C to 60°C, and in step S3, the reflux reaction temperature is 115°C to 120°C.

[0016] The mixed solvent is composed of anhydrous ethanol and ethyl acetate in a volume ratio of 1:2, the recrystallization times are 3 times, the drying method is vacuum drying, the drying temperature is 40° C. to 45° C., and the drying time is 48h to 50h.

[0017] The low-freezing-point multifunctional fracturing fluid aqueous agent is obtained by the following method: adding a required amount of dispersant to a required amount of water and mixing, then adding a required amount of betaine mixture and mixing, and then adding a required amount of cationic composition and mixing to obtain a low-freezing-point multifunctional fracturing fluid aqueous agent at a stirring speed of 1000 r / min.

[0018] The second technical solution of the present invention is achieved by the following measures: a method for preparing a low-freezing point multifunctional fracturing fluid aqueous agent is carried out as follows: at a stirring speed of 1000r / min, a required amount of dispersant is added to a required amount of water and mixed, then a required amount of betaine mixture is added and mixed, and then a required amount of cationic composition is added and mixed to obtain a low-freezing point multifunctional fracturing fluid aqueous agent.

[0019] The present invention uses a surfactant (betaine composition) that forms multiple hydrogen bonds and high-energy chemical bonds with water molecules to break the crystal structure between water molecules, and a surfactant (cationic composition) with high-energy chemical bonds allows the system to release more heat every time the temperature drops by 1°C, thereby maintaining the flow state of the low-freezing-point multifunctional fracturing fluid aqueous agent. The various raw materials of the present invention are mixed to obtain a low-freezing-point multifunctional fracturing fluid aqueous agent with excellent performance, a freezing point of -52°C, and the characteristics of assisting drainage, foaming and stabilizing viscosity, which effectively solves the problem of crystallization and incompatibility of most existing oil and gas well fracturing fluid aqueous agents in winter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of the polycarboxylic acid antifreeze prepared in Example 16 of the present invention. DETAILED DESCRIPTION

[0021] The present invention is not limited by the following embodiments, and specific implementation methods can be determined according to the technical scheme of the present invention and actual conditions. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; unless otherwise specified, the solutions in the present invention are all aqueous solutions in which the solvent is water, for example, the hydrochloric acid solution is an aqueous hydrochloric acid solution.

[0022] The present invention will be further described below in conjunction with embodiments: Example 1: The low-freezing-point multifunctional fracturing fluid aqueous agent comprises, by weight percentage, 30% to 40% of a dispersant, 15% to 25% of a betaine composition, 25% to 35% of a cationic composition and the remainder of water.

[0023] Example 2: As an optimization of the above example, the dispersant is a mixture of oligomer polyol, polycarboxylic acid antifreeze and low-carbon alcohol in a mass ratio of 1:1:(9.5 to 10.5), the oligomer polyol is one of polyethylene glycol, low-branched polyester polyol and polyester diol, and the low-carbon alcohol is one of methanol, ethylene glycol, glycerol and isopropanol.

[0024] In the present invention, the branching degree of the low-branching polyester polyol is 2% to 5%.

[0025] Example 3: As an optimization of the above example, in the dispersant, the polycarboxylic acid antifreeze is obtained by the following method: under stirring, allyl polyoxyethylene ether is added to deionized water and mixed, and then, 10% hydrogen peroxide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and 10% initiator solution are sequentially added dropwise to react to obtain a reaction product, and after adjusting the pH value of the reaction product, a polycarboxylic acid antifreeze with a mass concentration of 30% is obtained.

[0026] Example 4: As an optimization of the above example, in the preparation method of the polycarboxylic acid antifreeze, the mass ratio of deionized water to allyl polyoxyethylene ether is 2:5, and the molar ratio of allyl polyoxyethylene ether, acrylic acid, and 2-acrylamido-2-methylpropane sulfonic acid is 1:2:0.6.

[0027] Example 5: As an optimization of the above example, in the preparation method of the polycarboxylic acid antifreeze, the added amount of 10% hydrogen peroxide and 10% initiator solution is 3.0% to 3.5% of the total mass of allyl polyoxyethylene ether, and the initiator is sodium bisulfite.

[0028] Example 6: As an optimization of the above example, in the preparation method of the polycarboxylic acid antifreeze, the dropping time is 1 to 2 hours, the reaction time is 2 hours, and the pH value of the reaction product is adjusted to 7.

[0029] Example 7: As an optimization of the above example, the betaine composition is prepared by mixing lauramidopropyl hydroxysulfobetaine and cocoamidopropyl betaine in a mass ratio of 5:1.

[0030] Example 7: As an optimization of the above example, the cationic composition is composed of a mixture of a gemini quaternary ammonium salt surfactant, a small cationic surfactant and an inorganic salt in a mass ratio of 6:1:1, the small cationic surfactant is one or more of dimethyldiallylammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride and hexadecyltrimethylammonium chloride, and the inorganic salt is potassium chloride.

[0031] Embodiment 8: As an optimization of the above embodiment, in the cationic composition, the Gemini quaternary ammonium salt surfactant is a quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane, and the 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane is obtained by the following method: S1, add 480mmol of dodecane bromide and 2.08mol of diethanolamine to anhydrous ethanol to react under reflux for 10h to 12h to obtain product 1, cool product 1 to room temperature, add 0.7mol of sodium hydroxide to product 1 and continue to react for 1.0h to 1.5h to obtain product 2; S2, subjecting the product 2 to rotary evaporation, ether dissolution and suction filtration in sequence to obtain a filtrate, and subjecting the filtrate to rotary evaporation and reduced pressure distillation to obtain dodecyldiethanolamine; S3, adding 1,3-dibromoisopropanol and anhydrous ethanol to dodecyldiethanolamine in sequence and performing reflux reaction for 70 to 72 hours to obtain product three, cooling product three to room temperature, and then performing rotary evaporation to obtain a residue; S4, dissolving the residue in anhydrous ethanol, recrystallizing with a mixed solvent and drying in sequence to obtain 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane.

[0032] Example 9: As an optimization of the above example, in step S3, the mass ratio of dodecyldiethanolamine to 1,3-dibromoisopropanol is 13:1.

[0033] Example 10: As an optimization of the above example, in step S1, the reflux reaction temperature is 55°C to 60°C, and in step S3, the reflux reaction temperature is 115°C to 120°C.

[0034] Example 11: As an optimization of the above example, the mixed solvent is a mixture of anhydrous ethanol and ethyl acetate in a volume ratio of 1:2, the recrystallization times are 3 times, the drying method is vacuum drying, the drying temperature is 40°C to 45°C, and the drying time is 48h to 50h.

[0035] Example 12: As an optimization of the above example, a low-freezing point multifunctional fracturing fluid aqueous agent is obtained by the following method: at a stirring speed of 1000 r / min, a required amount of dispersant is added to a required amount of water and mixed, then a required amount of betaine mixture is added and mixed, and then a required amount of cationic composition is added and mixed to obtain a low-freezing point multifunctional fracturing fluid aqueous agent.

[0036] Embodiment 13: The low-freezing-point multifunctional fracturing fluid aqueous agent comprises, by weight percentage, 30% of a dispersant (a mixture of oligomer polyol (polyethylene glycol), polycarboxylic acid antifreeze and low-carbon alcohol (methanol) in a mass ratio of 1:1:9.5), 15% of a betaine composition (laurylamide propyl hydroxysulfobetaine and cocamidopropyl betaine in a mass ratio of 5:1), 25% of a cationic composition (gemini quaternary ammonium salt surfactant, small cationic surfactant (dimethyldiallyl ammonium chloride) and inorganic salt (potassium chloride) in a mass ratio of 6:1:1) and the remainder of water, and is obtained by the following method: adding a required amount of dispersant to a required amount of water and mixing, then adding a required amount of betaine mixture and mixing, and then continuing to add a required amount of cationic composition and mixing, to obtain a low-freezing-point multifunctional fracturing fluid aqueous agent. Among them, In the dispersant, the polycarboxylic acid antifreeze is obtained by the following method: under stirring, allyl polyoxyethylene ether is added to deionized water and mixed, and then, 10% hydrogen peroxide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and 10% initiator solution are added dropwise in sequence, and the dropping time is controlled for 1 hour, and then the reaction is allowed to occur, and the reaction is carried out for 2 hours to obtain a reaction product, and the pH value of the reaction product is adjusted to 7 to obtain a polycarboxylic acid antifreeze with a mass concentration of 30%, wherein the mass ratio of deionized water to allyl polyoxyethylene ether is 2:5, the molar ratio of allyl polyoxyethylene ether, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid is 1:2:0.6, the addition amount of 10% hydrogen peroxide and 10% initiator solution is 3.0% of the total mass of allyl polyoxyethylene ether, and the initiator is sodium bisulfite; In the cationic composition, the Gemini quaternary ammonium salt surfactant is a quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane. The 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane is obtained by the following method: S1, add 480mmol of bromododecane and 2.08mol of diethanolamine to anhydrous ethanol and reflux (55°C) for 12h to obtain product 1, cool product 1 to room temperature, add 0.7mol of sodium hydroxide to product 1 and continue to react for 1.0h to obtain product 2; S2, subjecting the product 2 to rotary evaporation, ether dissolution and suction filtration in sequence to obtain a filtrate, and subjecting the filtrate to rotary evaporation and reduced pressure distillation to obtain dodecyldiethanolamine; S3, adding 1,3-dibromoisopropanol and anhydrous ethanol to dodecyldiethanolamine in sequence, and reacting under reflux (115°C) for 72 hours to obtain product three, cooling product three to room temperature, and then performing rotary evaporation to obtain a residue, wherein the mass ratio of dodecyldiethanolamine to 1,3-dibromoisopropanol is 13:1; S4, the residue was dissolved in anhydrous ethanol, recrystallized from a mixed solvent (anhydrous ethanol and ethyl acetate in a volume ratio of 1:2) for three times, and dried in vacuo at 40° C. for 48 h to obtain 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane.

[0037] Embodiment 14: The low-freezing-point multifunctional fracturing fluid aqueous agent comprises, by weight percentage, 40% of a dispersant (a mixture of oligomer polyols (low-branching degree polyester polyols), polycarboxylic acid antifreeze and low-carbon alcohol (ethylene glycol) in a mass ratio of 1:1:10.5), 25% of a betaine composition (laurylamide propyl hydroxysulfobetaine and cocamidopropyl betaine in a mass ratio of 5:1), 35% of a cationic composition (gemini quaternary ammonium salt surfactant, small cationic surfactant (3-chloro-2-hydroxypropyltrimethylammonium chloride) and inorganic salt (potassium chloride) in a mass ratio of 6:1:1) and the remainder of water, and is obtained by the following method: adding a required amount of dispersant to a required amount of water and mixing, then adding a required amount of betaine mixture and mixing, and then adding a required amount of cationic composition and mixing, to obtain a low-freezing-point multifunctional fracturing fluid aqueous agent. Among them, In the dispersant, the polycarboxylic acid antifreeze is obtained by the following method: under stirring, allyl polyoxyethylene ether is added to deionized water and mixed, and then, 10% hydrogen peroxide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and 10% initiator solution are added dropwise in sequence, and the dropping time is controlled to be 2h, and then the reaction is allowed to occur, and the reaction is carried out for 2h to obtain a reaction product, and the pH value of the reaction product is adjusted to 7 to obtain a polycarboxylic acid antifreeze with a mass concentration of 30%, wherein the mass ratio of deionized water to allyl polyoxyethylene ether is 2:5, the molar ratio of allyl polyoxyethylene ether, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid is 1:2:0.6, and the addition amount of 10% hydrogen peroxide and 10% initiator solution is 3.5% of the total mass of allyl polyoxyethylene ether; In the cationic composition, the Gemini quaternary ammonium salt surfactant is a quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane. The 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane is obtained by the following method: S1, add 480mmol of bromododecane and 2.08mol of diethanolamine to anhydrous ethanol and reflux (55℃ to 60℃) for 12h to obtain product 1, cool product 1 to room temperature, add 0.7mol of sodium hydroxide to product 1 and continue to react for 1.5h to obtain product 2; S2, subjecting the product 2 to rotary evaporation, ether dissolution and suction filtration in sequence to obtain a filtrate, and subjecting the filtrate to rotary evaporation and reduced pressure distillation to obtain dodecyldiethanolamine; S3, adding 1,3-dibromoisopropanol and anhydrous ethanol to dodecyldiethanolamine in sequence, and reacting at reflux (120°C) for 72 hours to obtain product three, cooling product three to room temperature, and then performing rotary evaporation to obtain a residue, wherein the mass ratio of dodecyldiethanolamine to 1,3-dibromoisopropanol is 13:1; S4, the residue was dissolved in anhydrous ethanol, recrystallized from a mixed solvent (anhydrous ethanol and ethyl acetate in a volume ratio of 1:2) for three times, and dried in vacuo at 40° C. for 48 h to obtain 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane.

[0038] Embodiment 15: The low-freezing-point multifunctional fracturing fluid aqueous agent comprises, by weight percentage, 35% of a dispersant (a mixture of oligomer polyol (polyester diol), polycarboxylic acid antifreeze and low-carbon alcohol (glycerol) in a mass ratio of 1:1:10), 20% of a betaine composition (laurylamide propyl hydroxysulfobetaine and cocamidopropyl betaine in a mass ratio of 5:1), 30% of a cationic composition (a gemini quaternary ammonium salt surfactant, a small cationic surfactant (hexadecyl trimethyl ammonium chloride) and an inorganic salt (potassium chloride) in a mass ratio of 6:1:1) and the remainder of water, and is obtained by the following method: adding a required amount of dispersant to a required amount of water and mixing, then adding a required amount of the betaine mixture and mixing, and then continuing to add a required amount of the cationic composition and mixing, to obtain a low-freezing-point multifunctional fracturing fluid aqueous agent. Among them, In the dispersant, the polycarboxylic acid antifreeze is obtained by the following method: under stirring, allyl polyoxyethylene ether is added to deionized water and mixed, and then, 10% hydrogen peroxide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and 10% initiator solution are added dropwise in sequence, and the dropping time is controlled to be 1.5 hours, and then the reaction is allowed to occur, and the reaction is carried out for 2 hours to obtain a reaction product, and the pH value of the reaction product is adjusted to 7 to obtain a polycarboxylic acid antifreeze with a mass concentration of 30%, wherein the mass ratio of deionized water to allyl polyoxyethylene ether is 2:5, the molar ratio of allyl polyoxyethylene ether, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid is 1:2:0.6, and the addition amount of 10% hydrogen peroxide and 10% initiator solution is 3.2% of the total mass of allyl polyoxyethylene ether; In the cationic composition, the Gemini quaternary ammonium salt surfactant is a quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane. The 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane is obtained by the following method: S1, add 480mmol of bromododecane and 2.08mol of diethanolamine to anhydrous ethanol and reflux (55℃ to 60℃) for 12h to obtain product 1, cool product 1 to room temperature, add 0.7mol of sodium hydroxide to product 1 and continue to react for 1.2h to obtain product 2; S2, subjecting the product 2 to rotary evaporation, ether dissolution and suction filtration in sequence to obtain a filtrate, and subjecting the filtrate to rotary evaporation and reduced pressure distillation to obtain dodecyldiethanolamine; S3, adding 1,3-dibromoisopropanol and anhydrous ethanol to dodecyldiethanolamine in sequence, and reacting under reflux (118°C) for 72 hours to obtain product three, cooling product three to room temperature, and then performing rotary evaporation to obtain a residue, wherein the mass ratio of dodecyldiethanolamine to 1,3-dibromoisopropanol is 13:1; S4, the residue was dissolved in anhydrous ethanol, recrystallized from a mixed solvent (anhydrous ethanol and ethyl acetate in a volume ratio of 1:2) for three times, and dried in vacuo at 40° C. for 48 h to obtain 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane.

[0039] Compared with the prior art, the present invention has the following beneficial effects: The raw material dispersant of the present invention is composed of oligomer polyol, polycarboxylic acid antifreeze and low-carbon alcohol in proportion. Among them, the oligomer polyol, on the one hand, can form hydrogen bonds with water molecules due to its rich hydroxyl groups to change the internal arrangement of water molecules and reduce the freezing point of the water agent. On the other hand, the oligomer polyol can also increase the viscosity of the water agent synchronously with the polycarboxylic acid antifreeze, thereby achieving the effect of stabilizing foam. The polycarboxylic acid antifreeze, with its carboxylate like-charge effect, allows carboxylate ions to contact with water molecules to the greatest extent, changing the arrangement of water molecules. Its hydrophobic end prevents water molecules from aggregating. At the same time, the polycarboxylic acid antifreeze, which is also rich in hydroxyl groups, sulfonic acid groups, etc., can form new hydrogen bonds with water molecules to "lock water and isolate" the water molecules internally, thereby breaking the internal hydrogen bond structure of the water molecules and achieving the purpose of lowering the freezing point and preventing freezing.

[0040] The raw material cationic composition of the present invention is composed of a Gemini quaternary ammonium surfactant, a small cationic surfactant and an inorganic salt in proportion, wherein the Gemini quaternary ammonium surfactant is a quaternary ammonium cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecyl ammonium bromide]propane. The surfactant contains five hydroxyl groups and quaternary ammonium cations, which can change the arrangement structure of water molecules to the greatest extent, so that the water molecules change from a "free state" to a "bound state", and high-energy chemical bonds ionize and release heat while forming large-scale hydrogen bonds with water molecules to reduce the freezing point, and at the same time, it also has a significant anti-swelling function. The small cationic surfactant can dissolve in water to ionize ions, has a higher bond energy to dissolve and release a large amount of heat to reduce the freezing point of the system.

[0041] The raw material betaine composition of the present invention is prepared by combining lauramide propyl hydroxysulfobetaine and cocoamidopropyl betaine in proportion, and has the advantages that the betaine composition can form hydrogen bonds with water molecules to reduce the freezing point, and on the other hand, the betaine composition has excellent foaming function, so that the water-based agent has excellent foaming performance, and at the same time, the betaine composition can interact with a dispersant to form a system with low surface tension and low interfacial tension.

[0042] The low-freezing-point multifunctional fracturing fluid aqueous agent of the present invention is prepared by mixing a dispersant, a betaine composition, a cationic composition and water in a certain proportion, and has the following advantages: (1) the freezing point is -25°C, which is much lower than the freezing point of the existing antifreeze aqueous agent on the market; (2) the anti-swelling rate is 96%, and the anti-swelling effect is better than the existing general anti-swelling agent; (3) the low-freezing-point multifunctional fracturing fluid aqueous agent with a concentration of 0.3% is prepared with 100,000 ppm mineralized water, and its foaming rate is 320% and the half-life is 480s; with distilled water The prepared concentration of the low-freezing-point multifunctional fracturing fluid aqueous agent is 0.3%, with a foaming rate of 360% and a half-life of 510s; (4) the surface tension is 25mN / m, and the interfacial tension is 1.5mN / m; (5) the low-freezing-point multifunctional fracturing fluid aqueous agent is an integrated auxiliary agent with no compatibility risk; (6) the dosage of the low-freezing-point multifunctional fracturing fluid aqueous agent is 0.3%, which is 40% lower than the conventional dosage, saving costs and meeting the antifreeze needs of winter construction in all domestic oil and gas production areas.

[0043] Embodiment 16: The low-freezing-point multifunctional fracturing fluid aqueous agent comprises, by weight percentage, 35% of a dispersant (a mixture of oligomer polyols (polyethylene glycol, low-branching polyester polyols and polyester diols) in a mass ratio of 1:1:10, a polycarboxylic acid antifreeze agent and low-carbon alcohols (methanol, ethylene glycol, glycerol and isopropanol)), 20% of a betaine composition (lauramidopropyl hydroxysulfobetaine and cocamidopropyl betaine in a mass ratio of 5:1), and 30% of a cationic composition (a gemini quaternary ammonium salt surfactant in a mass ratio of 6:1:1). , small cationic surfactants (dimethyldiallyl ammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride and hexadecyltrimethylammonium chloride) and inorganic salts (potassium chloride) and the rest of water, are obtained by the following method: at a stirring speed of 1000r / min, a required amount of dispersant is added to a required amount of water and stirred for 30 minutes, then a required amount of betaine mixture is added and stirred for 30 minutes, and then a required amount of cationic composition is added and stirred for 30 minutes to obtain a low-freezing point multifunctional fracturing fluid aqueous agent. Among them, In the dispersant, the polycarboxylic acid antifreeze is obtained by the following method: under stirring, 80g of allyl polyoxyethylene ether is added to 200g of deionized water and mixed, and then, 10% hydrogen peroxide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and 10% initiator solution are added dropwise in sequence, and the dropping time is controlled to be 1h to 2h, and then the reaction is allowed to occur, and the reaction is carried out for 2h to obtain a reaction product, and the pH value of the reaction product is adjusted to 7 to obtain a polycarboxylic acid antifreeze with a mass concentration of 30%, wherein the mass ratio of deionized water to allyl polyoxyethylene ether is 2:5, the molar ratio of allyl polyoxyethylene ether, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid is 1:2:0.6, and the addition amount of 10% hydrogen peroxide and 10% initiator solution is 3.0% of the total mass of allyl polyoxyethylene ether; In the cationic composition, the Gemini quaternary ammonium salt surfactant is a quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane. The 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane is obtained by the following method: S1, add 120g (480mmol) of bromododecane and 150g (2.08mol) of diethanolamine to 200mL of anhydrous ethanol and reflux (55°C) for 12h to obtain product 1, cool product 1 to room temperature, add 28g (0.7mol) of sodium hydroxide to product 1 and continue to react for 1.0h to 1.5h to obtain product 2; S2, after the product is subjected to rotary evaporation (to remove ethanol), 100 mL of ether is added to dissolve, solid is precipitated, and after suction filtration, a filtrate is obtained. After the filtrate is subjected to rotary evaporation (to remove ether), the residue is subjected to reduced pressure distillation to obtain dodecyldiethanolamine (yellow liquid); S3, 10 g (40 mmol) of 1,3-dibromoisopropanol and 20 mL of anhydrous ethanol were added to 130 g (120 mmol) of dodecyldiethanolamine in sequence, and the mixture was refluxed (115° C.) for 72 h to obtain product 3, and product 3 was cooled to room temperature and then subjected to rotary evaporation (to remove ethanol) to obtain a residue; S4, the residue was dissolved with 10 mL of anhydrous ethanol, recrystallized three times from a mixed solvent (anhydrous ethanol and ethyl acetate in a volume ratio of 1:2), and dried under vacuum at 40 °C for 48 h to obtain 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane (white powder).

[0044] The polycarboxylic acid antifreeze prepared in Example 16 of the present invention was subjected to infrared spectroscopy analysis, and its infrared spectrum is shown in FIG. Figure 1 As shown by Figure 1 It can be seen that 3422cm -1 The vibration peak of -OH is 1729cm -1 The vibration peak of -COOOH is 1631cm -1 、1560cm -1 The absorption peaks at the positions are -C=O and -NH, respectively. This shows that the polycarboxylic acid antifreeze synthesized under this condition is a product that can form extensive hydrogen bonds with water molecules, thereby profoundly affecting the arrangement structure of water molecules. Its freezing point is tested to be -75°C.

[0045] The low-freezing-point multifunctional fracturing fluid aqueous agent prepared in Example 16 of the present invention has excellent performance, specifically, a freezing point of -52°C, an anti-swelling rate of 96%, a foaming rate of 320%, a half-life of 480s, a surface tension of 25mN / m, an interfacial tension of 1.5mN / m, and a temperature-resistant and shear-resistant viscosity ≥200mPa·s.

[0046] Example 17: The lowest temperature in the oil and gas production area of ​​the Sulige gas field reaches -35°C in winter. In the winter of 2021, the existing conventional steam boiler was used for thawing operations in the fracturing construction. Five wells were constructed and the amount of fluid entering the wells was 40,000 cubic meters. During the period, the pump was stopped 6 times due to freezing and blockage, and the construction efficiency was reduced by 2.5 times compared with normal conditions; in the winter of 2022, 8 wells were constructed and the amount of fluid entering the wells reached 80,000 cubic meters. The business volume doubled compared with 2022. Guar gum fracturing fluid was used (the cross-linking ratio of the fracturing fluid was 100:0.3). The formula of the guar gum fracturing fluid is: 0.35% guar gum + 0.3% low-freezing point multifunctional fracturing fluid aqueous agent prepared in Example 16 of the present invention.

[0047] Fracturing construction results: The guar gum fracturing fluid containing the low-freezing-point multifunctional fracturing fluid aqueous agent of the present invention was used, so that the production area did not freeze in the winter with a minimum temperature of -35°C and without using a steam boiler. The highest sand ratio of the construction was 35%, the average sand ratio was 22%, the low-freezing-point multifunctional fracturing fluid aqueous agent was flowable throughout the process, and the construction success rate was 100%.

[0048] In summary, the present invention breaks the crystal structure between water molecules by using a surfactant (betaine composition) having multiple hydrogen bonds and high-energy chemical bonds with water molecules, and a surfactant (cationic composition) having high-energy chemical bonds enables the system to release more heat for every 1°C decrease in temperature, thereby maintaining the flow state of the low-freezing-point multifunctional fracturing fluid aqueous agent. The various raw materials of the present invention are mixed to obtain a low-freezing-point multifunctional fracturing fluid aqueous agent with excellent performance, a freezing point of -52°C, and the characteristics of drainage assistance, foaming and viscosity stability, which effectively solves the problem of crystallization and incompatibility of most existing oil and gas well fracturing fluid aqueous agents in winter.

[0049] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A low-freezing-point multifunctional fracturing fluid aqueous agent, characterized in that The raw materials include, by weight percentage, 30% to 40% of a dispersant, 15% to 25% of a betaine composition, 25% to 35% of a cationic composition and the balance of water.

2. The low-freezing-point multifunctional fracturing fluid aqueous agent according to claim 1, characterized in that The dispersant is a mixture of oligomer polyol, polycarboxylic acid antifreeze and low-carbon alcohol in a mass ratio of 1:1:9.5 to 10.

5. The oligomer polyol is one of polyethylene glycol, low-branching polyester polyol and polyester diol, and the low-carbon alcohol is one of methanol, ethylene glycol, glycerol and isopropanol.

3. The low-freezing-point multifunctional fracturing fluid aqueous agent according to claim 2, characterized in that In the dispersant, the polycarboxylic acid antifreeze is obtained by the following method: allyl polyoxyethylene ether is added to deionized water under stirring and mixed, and then hydrogen peroxide with a mass concentration of 10%, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and an initiator solution with a mass concentration of 10% are sequentially added dropwise to react to obtain a reaction product, and after adjusting the pH value of the reaction product, a polycarboxylic acid antifreeze with a mass concentration of 30% is obtained.

4. The low-freezing-point multifunctional fracturing fluid aqueous agent according to claim 3, characterized in that In the preparation method of the polycarboxylic acid antifreeze, the mass ratio of deionized water to allyl polyoxyethylene ether is 2:5, and the molar ratio of allyl polyoxyethylene ether, acrylic acid, and 2-acrylamide-2-methylpropane sulfonic acid is 1:2:0.6; or / and, the addition amount of hydrogen peroxide with a mass concentration of 10% and the initiator solution with a mass concentration of 10% is 3.0% to 3.5% of the total mass of allyl polyoxyethylene ether, and the initiator is sodium bisulfite; or / and, the dropping time is 1h to 2h, the reaction time is 2h, and the pH value of the reaction product is adjusted to 7.

5. The low-freezing-point multifunctional fracturing fluid aqueous agent according to any one of claims 1 to 4, characterized in that The betaine composition is prepared by mixing lauryl hydroxysulfobetaine and cocoamidopropyl betaine in a mass ratio of 5:

1.

6. The low-freezing-point multifunctional fracturing fluid aqueous agent according to any one of claims 1 to 5, characterized in that The cationic composition is prepared by mixing a gemini quaternary ammonium surfactant, a small cationic surfactant and an inorganic salt in a mass ratio of 6:1:

1. The small cationic surfactant is one or more of dimethyldiallylammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride and hexadecyltrimethylammonium chloride, and the inorganic salt is potassium chloride.

7. The low-freezing-point multifunctional fracturing fluid aqueous agent according to claim 6, characterized in that In the cationic composition, the Gemini quaternary ammonium salt surfactant is a quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region, and the quaternary ammonium salt cationic Gemini surfactant containing five hydroxyl groups in the head group region is 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane. The 2-hydroxy-1,3-bis[di(2-hydroxyethyl)dodecylammonium bromide]propane is obtained by the following method: S1, add 480mmol of dodecane bromide and 2.08mol of diethanolamine to anhydrous ethanol to react under reflux for 10h to 12h to obtain product 1, cool product 1 to room temperature, add 0.7mol of sodium hydroxide to product 1 and continue to react for 1.0h to 1.5h to obtain product 2; S2, subjecting the product 2 to rotary evaporation, ether dissolution and suction filtration in sequence to obtain a filtrate, and subjecting the filtrate to rotary evaporation and reduced pressure distillation to obtain dodecyldiethanolamine; S3, adding 1,3-dibromoisopropanol and anhydrous ethanol to dodecyldiethanolamine in sequence and performing reflux reaction for 70 to 72 hours to obtain product three, cooling product three to room temperature, and then performing rotary evaporation to obtain a residue; S4, dissolving the residue in anhydrous ethanol, recrystallizing with a mixed solvent and drying in sequence to obtain 2-hydroxy-1,3-bis[bis(2-hydroxyethyl)dodecylammonium bromide]propane.

8. The low-freezing-point multifunctional fracturing fluid aqueous agent according to claim 7, characterized in that In step S3, the mass ratio of dodecyldiethanolamine to 1,3-dibromoisopropanol is 13:1; or / and, in step S1, the reflux reaction temperature is 55°C to 60°C, and in step S3, the reflux reaction temperature is 115°C to 120°C; or / and, the mixed solvent is a mixture of anhydrous ethanol and ethyl acetate in a volume ratio of 1:2, the number of recrystallizations is 3 times, the drying method is vacuum drying, the drying temperature is 40°C to 45°C, and the drying time is 48h to 50h.

9. The low-freezing-point multifunctional fracturing fluid aqueous agent according to any one of claims 1 to 8, characterized in that The method is as follows: adding a required amount of dispersant to a required amount of water and mixing evenly, then adding a required amount of betaine mixture and mixing evenly, and then adding a required amount of cationic composition and mixing evenly to obtain a low-freezing point multifunctional fracturing fluid aqueous agent at a stirring speed of 1000 r / min.

10. A method for preparing a low-freezing-point multifunctional fracturing fluid aqueous agent according to any one of claims 1 to 8, characterized in that The method is as follows: at a stirring speed of 1000 r / min, a required amount of dispersant is added to a required amount of water and mixed evenly, then a required amount of betaine mixture is added and mixed evenly, and then a required amount of cationic composition is added and mixed evenly to obtain a low-freezing point multifunctional fracturing fluid aqueous agent.

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