Salt-resistant foaming agent for oil field development and preparation method thereof

Abstract

The invention discloses a salt-resistant foaming agent for oilfield development and a preparation method thereof, belonging to the technical field of foaming agent preparation. The salt-resistant foaming agent for oilfield development is composed of the following components by weight: 15-25 parts of a primary surfactant, 5-10 parts of cocamidopropyl betaine, 0.1-0.6 parts of a cosurfactant, 1-4 parts of disodium EDTA, 0.05-0.12 parts of nano-silicon dioxide, and 3-6 parts of isopropyl alcohol. The foaming agent prepared by the present invention has excellent salt resistance and stability.

Description

Technical Field

[0001] The invention belongs to the technical field of foaming agent preparation, and particularly relates to a salt-resistant foaming agent for oil field development and a preparation method thereof. Background Art

[0002] During the development of oil and gas fields, liquid accumulation in gas wells is one of the key problems that restrict the stable production of low-permeability, low-pressure gas wells. As gas field development enters the middle and late stages, the formation energy gradually depletes, and the amount of liquid accumulated at the bottom of the well increases significantly, resulting in a sharp decline in gas well production capacity or even shutdown. As an economical and efficient means of drainage, foam drainage gas production technology relies on the formation of a low-density foam system in the wellbore through the use of foaming agents, and the use of the gas-liquid two-phase flow characteristics to carry the accumulated liquid to the surface. However, the application limitations of traditional foaming agents in complex oil and gas reservoir environments are becoming increasingly prominent, especially under high temperature, high salinity and long-term production conditions. Their insufficient foaming performance, salt resistance and stability have become the core bottlenecks restricting the effectiveness of the technology.

[0003] Patent CN112226219B discloses a gel-type foam system flow regulator, its preparation method, and application. In this invention, the raw materials for preparing the gel-type foam system flow regulator include 0.3-0.6% by weight of sodium alginate, 0.1-0.2% by weight of a foaming agent, 0.02-0.05% by weight of a calcium salt, 6-12% by weight of a monomer, 0.4-0.8% by weight of an initiator A, 0.1-1% by weight of an initiator B, 0.05-0.1% by weight of a foam stabilizer, and the balance being water. This gel-type foam system flow regulator is suitable for plugging gas channeling in high-temperature, high-salinity oil reservoirs. It has good mechanical and structural strength and good shear resistance. However, the stability and salt tolerance of the foaming agent prepared by this method still need to be improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a salt-resistant foaming agent for oil field development and a preparation method thereof, so as to solve the technical problems of poor stability and salt resistance of the foaming agent in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The invention provides a salt-resistant foaming agent for oilfield development. The foaming agent is composed of the following components in parts by weight: 15-25 parts of a main surfactant, 5-10 parts of cocamidopropyl betaine, 0.1-0.6 parts of a cosurfactant, 1-4 parts of disodium EDTA, 0.05-0.12 parts of nano silicon dioxide, and 3-6 parts of isopropyl alcohol.

[0007] Preferably, the preparation method of the primary surfactant comprises the following steps:

[0008] Q1: 1-dodecanol and dodecylbenzenesulfonic acid were added to a container, mixed and stirred, and then glucose was added and heated for reaction. After the reaction was completed, the temperature was lowered, and sodium hydroxide solution was added to quench the reaction. The pH was adjusted, vacuum filtered, rotary evaporated, distilled water was added, and the mixture was stirred in an oil bath, cooled, and freeze-dried to obtain product 1;

[0009] Q2: Add product 1 to pyridine, stir to dissolve, and then slowly dropwise add toluene containing chloroacetyl chloride in an ice bath. After the addition is complete, react at room temperature. After the reaction is complete, filter, distill under reduced pressure, and dry in vacuo to obtain product 2.

[0010] Q3: Add polyethylene glycol monomethyl ether to a container, then add boron trifluoride ether complex, slowly add epichlorohydrin dropwise, stir to react, and after the reaction is completed, distill under reduced pressure, slowly add sodium hydroxide solution dropwise, continue to stir to react, and after the reaction is completed, distill under reduced pressure, filter, add to a container containing N,N'-dimethylethylenediamine, stir to react, and after the reaction is completed, distill under reduced pressure to obtain product 3;

[0011] Q4: Add product 2 and product 3 to a container containing N,N-dimethylformamide, then add potassium iodide, heat to condense and reflux to react. After the reaction is completed, distill under reduced pressure, wash, and dry to obtain the main surfactant.

[0012] In the above process, dodecylbenzenesulfonic acid provides hydrogen ions to activate the anomeric carbon hydroxyl group of glucose, and then the hydroxyl group of 1-dodecanol acts as a nucleophile to attack the activated carbon, undergoing a nucleophilic substitution reaction to obtain product 1; then the hydroxyl group in product 1 undergoes an esterification reaction with the acyl chloride group in chloroacetyl chloride to obtain product 2; then the hydroxyl group in polyethylene glycol monomethyl ether undergoes a substitution reaction with the chlorine group in epichlorohydrin, and then continues to undergo an epoxy ring-opening reaction with N,N'-dimethylethylenediamine to obtain product 3; finally, product 2 and product 3 undergo a quaternization reaction to obtain the main surfactant.

[0013] Preferably, in Q1, the molar ratio of 1-dodecanol, dodecylbenzenesulfonic acid and glucose is (4-7): (0.9-1.2): (0.03-0.05), the heating reaction temperature is 80-110°C, the reaction time is 6-9h, the temperature is lowered to 55-65°C, the pH is adjusted to 7-8, and the oil bath stirring temperature is 90-120°C; in Q2, the molar ratio of product 1 and chloroacetyl chloride is (0.9-1.2): (0.98-1.45), the ice bath environment temperature is 2-5°C, and the reaction time at room temperature is 6-8h.

[0014] Preferably, in Q3, the usage ratio of polyethylene glycol monomethyl ether, boron trifluoride ethyl ether complex, epichlorohydrin and N,N'-dimethylethylenediamine is (3-6.4) g: (0.015-0.022) g: (0.9-1.3) mL: (1.1-1.6) g.

[0015] Preferably, in Q4, the dosage ratio of product 2, product 3, N,N-dimethylformamide and potassium iodide is (1-1.8) g: (1.12-1.98) g: (20-35) mL: (0.016-0.0189) g, the heating condensation reflux reaction temperature is 100-110°C, and the reaction time is 48-52 h.

[0016] Preferably, the preparation method of the cosurfactant comprises the following steps:

[0017] S1: Add p-methoxyaniline to a container filled with deionized water, stir evenly, slowly add hydrochloric acid aqueous solution dropwise, fully dissolve, and stir in an ice bath to obtain solution a, add sodium nitrite to a container filled with deionized water, stir to dissolve, and place in an ice bath to obtain solution b, slowly add solution b to solution a, stir and react to obtain solution c, mix sodium hydroxide, sodium bicarbonate and deionized water, and then add phenol, and place in an ice bath to obtain solution d, slowly add solution c to solution d, continue stirring and reacting after the addition is complete, acidify, filter, wash, and recrystallize to obtain intermediate A;

[0018] S2: Add intermediate A, ethyl 6-bromohexanoate, potassium iodide, and potassium carbonate to N,N-dimethylformamide, and heat under argon protection to react. After the reaction is completed, acidify, filter, wash, and recrystallize to obtain intermediate B;

[0019] S3: adding intermediate B to anhydrous ethanol, then adding potassium hydroxide and stirring, heating for reaction, acidifying, filtering, drying, and recrystallizing to obtain intermediate C;

[0020] S4: Add glycerol polyoxyethylene ether to a container, then add intermediate C and p-toluenesulfonic acid, and react by stirring in an oil bath. After the reaction is completed, cool and vacuum dry to obtain a co-surfactant.

[0021] In the above process, the synthesis reaction formula of the co-surfactant is as follows:

[0022]

[0023] The results of mass spectrometry analysis of intermediate A were: m / z: 228.09 (100.0%), 229.09 (14.9%); the results of mass spectrometry analysis of intermediate B were: m / z: 370.19 (100.0%), 371.19 (23.6%), 372.20 (2.6%), 372.19(1.0%); the results of mass spectrometry analysis of intermediate C were: m / z: 342.16 (100.0%), 343.16 (21.0%), 344.16(3.0%).

[0024] Preferably, in S1, the amount ratio of p-anisidine, sodium nitrite, sodium hydroxide, sodium bicarbonate and phenol is (10-12) g: (6.7-7.8) g: (4.82-5.02) g: (10.1-12.4) g: (7-8.5) g; in S2, the amount ratio of intermediate A, ethyl 6-bromohexanoate, potassium iodide, potassium carbonate and N,N-dimethylformamide is (5-6) g: (7.33-7.82) g: (0.145-0.172) g: (9.01-9.48) g: (120-150) mL, the heating reaction temperature is 80-85°C, and the reaction time is 7-9 h.

[0025] Preferably, in S3, the amount ratio of intermediate B, anhydrous ethanol and potassium hydroxide is (5-7.5) g: (200-300) mL: (6.01-7.84) g, the heating reaction temperature is 70-80°C, and the reaction time is 10-12 h; in S4, the amount ratio of glycerol polyoxyethylene ether, intermediate C and p-toluenesulfonic acid is (8-12) g: (7-10.4) g: (0.03-0.046) g, the oil bath stirring reaction temperature is 110-140°C, and the reaction time is 3-6 h.

[0026] Preferably, the method for preparing a salt-resistant foaming agent for oil field development comprises the following steps:

[0027] Step 1: Add the main surfactant to the reactor, heat it, then slowly add cocamidopropyl betaine, continue stirring to obtain the main mixture;

[0028] Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silicon dioxide and isopropyl alcohol, stir and mix, let stand, filter, and homogenize to obtain a salt-resistant foaming agent for oil field development.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. The present invention adds the prepared main surfactant and co-surfactant to the preparation process of the foaming agent, which can effectively improve the stability and salt resistance of the foaming agent.

[0031] 2. The present invention uses the prepared main surfactant as one of the main components of the foaming agent, which can effectively improve the stability and salt resistance of the foaming agent. The quaternary ammonium salt structure contained in the main surfactant is positively charged and combines with high-valent metal ions such as calcium and magnesium in formation water through a charge shielding effect to avoid salting out. The ether oxygen atoms contained in the main surfactant can form hydrogen bonds with water molecules, and the long-chain steric hindrance prevents salt ions from approaching the polar head of the surfactant, thereby reducing salt sensitivity. The dynamic hydrogen bond network formed can enhance the hydration stability of the surfactant in a high-salt environment. The hydrophobic tail and the flexible hydrophilic chain contained in the main surfactant can be co-adsorbed at the gas-liquid interface to form an interfacial film. The quaternary ammonium salt structure enhances the mechanical strength of the film and resists film rupture caused by salt ions. The formed three-dimensional network structure can also improve the viscoelasticity of the foam liquid film and delay the foam collapse caused by drainage and gas diffusion.

[0032] 3. The present invention uses the prepared co-surfactant as one of the main components of the foaming agent, which can effectively improve the stability and salt resistance of the foaming agent. The polyoxyethylene chains contained in the co-surfactant form a hydration layer, which hinders high-valent ions from approaching the polar head of the surfactant and reduces salting out precipitation. The rigid structure of the azobenzene contained in the co-surfactant can prevent salt-induced molecular curling and improve the salt resistance of the foaming agent. The hydrophobic azobenzene group contained in the co-surfactant can be synergistically adsorbed with the polyoxyethylene chain at the gas-liquid interface to form a dense and elastic interface film, which resists salt ion damage and thus improves stability. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Example 1: This example discloses a method for preparing a primary surfactant, comprising the following steps:

[0035] Q1: 5.5 g of 1-dodecanol and 1.03 g of dodecylbenzenesulfonic acid were added to a container and mixed. 0.04 g of glucose was then added and heated at 100°C for 8 h. After the reaction, the temperature was lowered to 60°C and 1 mL of 5 wt% sodium hydroxide solution was added to quench the reaction. The pH was adjusted to 7, vacuum filtered, rotary evaporated, distilled water was added, and the mixture was stirred in an oil bath at 110°C. The mixture was cooled and freeze-dried to obtain product 1.

[0036] Q2: Add 2.84 g of product 1 to 10 mL of pyridine, stir to dissolve, and then slowly dropwise add 8 mL of toluene containing 1 g of chloroacetyl chloride in an ice bath at 3°C. After the addition is complete, react at room temperature for 8 h. After the reaction is complete, filter, evaporate under reduced pressure, and dry in vacuo to obtain product 2.

[0037] Q3: 4.7 g of polyethylene glycol monomethyl ether was added to a container, followed by the addition of 0.018 g of boron trifluoride etherate, and 1.1 mL of epichlorohydrin was slowly added dropwise, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure, and sodium hydroxide solution was slowly added dropwise, and the reaction was continued with stirring. After the reaction was completed, the mixture was distilled under reduced pressure, filtered, and added to a container containing 1.35 g of N,N'-dimethylethylenediamine, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure to obtain product 3;

[0038] Q4: Add 1.4 g of product 2 and 1.55 g of product 3 to a container containing 27.5 mL of N,N-dimethylformamide, then add 0.017 g of potassium iodide, heat at 105°C, condense and reflux for 48 hours. After the reaction is completed, distill under reduced pressure, wash, and dry to obtain the main surfactant.

[0039] This embodiment discloses a method for preparing a cosurfactant, comprising the following steps:

[0040] S1: 11 g of p-methoxyaniline was added to a container containing 100 mL of deionized water, and after stirring evenly, 120 mL of a 2 mol / L hydrochloric acid aqueous solution was slowly added dropwise. After fully dissolved, the mixture was stirred in an ice bath at 0°C to obtain solution a. 7.2 g of sodium nitrite was added to a container containing 50 mL of deionized water, stirred to dissolve, and placed in an ice bath at 0°C to obtain solution b. Solution b was slowly added to solution a, and the mixture was stirred at 0°C for 60 minutes to obtain solution c. 4.92 g of sodium hydroxide, 11.2 g of sodium bicarbonate, and 50 mL of deionized water were mixed, and then 7.7 g of phenol was added. The mixture was placed in an ice bath at 0°C to obtain solution d. Solution c was slowly added to solution d. After the addition was completed, the mixture was stirred and reacted for 100 minutes. After the reaction was completed, the mixture was acidified, filtered, washed, and recrystallized to obtain intermediate A.

[0041] S2: 5.5 g of intermediate A, 7.53 g of ethyl 6-bromohexanoate, 0.159 g of potassium iodide, and 9.25 g of potassium carbonate were added to 135 mL of N,N-dimethylformamide. The mixture was heated at 85°C under argon protection for 8 h. After the reaction, the mixture was acidified, filtered, washed, and recrystallized to obtain intermediate B.

[0042] S3: 6.25 g of intermediate B was added to 250 mL of anhydrous ethanol, followed by 6.92 g of potassium hydroxide, stirred, heated at 80°C for 12 h, acidified, filtered, dried, and recrystallized to obtain intermediate C;

[0043] S4: Add 10 g of glycerol polyoxyethylene ether to a container, then add 8.7 g of intermediate C and 0.038 g of p-toluenesulfonic acid, and stir in an oil bath at 120° C. for 6 h. After the reaction is completed, cool and vacuum dry to obtain a co-surfactant.

[0044] This embodiment discloses a salt-resistant foaming agent for oilfield development, which is composed of the following ingredients in parts by weight: 20 parts of a primary surfactant, 7.5 parts of cocamidopropyl betaine, 0.35 parts of a cosurfactant, 2.5 parts of disodium EDTA, 0.08 parts of nano-silicon dioxide, and 4.5 parts of isopropyl alcohol.

[0045] This embodiment discloses a method for preparing a salt-resistant foaming agent for oil field development, comprising the following steps:

[0046] Step 1: Add the main surfactant to the reactor, heat it, then slowly add cocamidopropyl betaine, continue stirring to obtain the main mixture;

[0047] Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silicon dioxide and isopropyl alcohol, stir and mix, let stand, filter, and homogenize to obtain a salt-resistant foaming agent for oil field development.

[0048] Example 2: This example discloses a method for preparing a primary surfactant, comprising the following steps:

[0049] Q1: 5 g of 1-dodecanol and 0.92 g of dodecylbenzenesulfonic acid were added to a container and mixed. 0.06 g of glucose was then added and heated at 100°C for 8 h. After the reaction, the temperature was lowered to 60°C and 1 mL of 5 wt% sodium hydroxide solution was added to quench the reaction. The pH was adjusted to 7, vacuum filtered, rotary evaporated, distilled water was added, and the mixture was stirred in an oil bath at 110°C. The mixture was cooled and freeze-dried to obtain product 1.

[0050] Q2: Add 1.91 g of product 1 to 10 mL of pyridine, stir to dissolve, and then slowly dropwise add 8 mL of toluene containing 1 g of chloroacetyl chloride in an ice bath at 3°C. After the addition is complete, react at room temperature for 8 h. After the reaction is complete, filter, evaporate under reduced pressure, and dry in vacuo to obtain product 2.

[0051] Q3: 3 g of polyethylene glycol monomethyl ether was added to a container, followed by the addition of 0.015 g of boron trifluoride etherate, and 0.9 mL of epichlorohydrin was slowly added dropwise, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure, and sodium hydroxide solution was slowly added dropwise, and the reaction was continued with stirring. After the reaction was completed, the mixture was distilled under reduced pressure, filtered, and added to a container containing 1.1 g of N,N'-dimethylethylenediamine, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure to obtain product 3;

[0052] Q4: Add 1 g of product 2 and 1.12 g of product 3 to a container containing 20 mL of N,N-dimethylformamide, then add 0.016 g of potassium iodide, heat at 105°C, condense and reflux for 48 hours. After the reaction is completed, distill under reduced pressure, wash, and dry to obtain the main surfactant.

[0053] This embodiment discloses a method for preparing a cosurfactant, comprising the following steps:

[0054] S1: Add 10g of p-anisidine to a container filled with 100mL of deionized water, stir evenly, slowly add 120mL of 2mol / L hydrochloric acid aqueous solution, fully dissolve, and stir in an ice bath at 0℃ to obtain solution a, add 6.7g of sodium nitrite to a container filled with 50mL of deionized water, stir to dissolve, and place in an ice bath at 0℃ to obtain solution b, slowly add solution b to solution a, stir and react at 0℃ for 60min to obtain solution c, mix 4.82g of sodium hydroxide, 10.1g of sodium bicarbonate and 50mL of deionized water, then add 7g of phenol, and place in an ice bath at 0℃ to obtain solution d, slowly add solution c to solution d, and after the addition is complete, continue stirring and reacting for 100min. After the reaction is completed, acidify, filter, wash, and recrystallize to obtain intermediate A;

[0055] S2: 5 g of intermediate A, 7.33 g of ethyl 6-bromohexanoate, 0.145 g of potassium iodide, and 9.01 g of potassium carbonate were added to 120 mL of N,N-dimethylformamide. The mixture was heated at 85°C under argon protection for 8 h. After the reaction, the mixture was acidified, filtered, washed, and recrystallized to obtain intermediate B.

[0056] S3: 5 g of intermediate B was added to 200 mL of anhydrous ethanol, followed by the addition of 6.01 g of potassium hydroxide, followed by stirring. The mixture was heated at 80°C for 12 h, acidified, filtered, dried, and recrystallized to obtain intermediate C.

[0057] S4: Add 12 g of glycerol polyoxyethylene ether to a container, then add 7 g of intermediate C and 0.03 g of p-toluenesulfonic acid, and stir in an oil bath at 120°C for 6 h. After the reaction is completed, cool and vacuum dry to obtain a co-surfactant.

[0058] This embodiment discloses a salt-resistant foaming agent for oilfield development, which is composed of the following ingredients in parts by weight: 15 parts of a primary surfactant, 5 parts of cocamidopropyl betaine, 0.1 parts of a cosurfactant, 1 part of disodium EDTA, 0.05 parts of nano-silicon dioxide, and 3 parts of isopropyl alcohol.

[0059] This embodiment discloses a method for preparing a salt-resistant foaming agent for oil field development, comprising the following steps:

[0060] Step 1: Add the main surfactant to the reactor, heat it, then slowly add cocamidopropyl betaine, continue stirring to obtain the main mixture;

[0061] Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silicon dioxide and isopropyl alcohol, stir and mix, let stand, filter, and homogenize to obtain a salt-resistant foaming agent for oil field development.

[0062] Example 3: This example discloses a method for preparing a primary surfactant, comprising the following steps:

[0063] Q1: 6 g of 1-dodecanol and 1.17 g of dodecylbenzenesulfonic acid were added to a container and mixed. 0.02 g of glucose was then added and heated at 100°C for 8 h. After the reaction, the temperature was lowered to 60°C and 1 mL of 5 wt% sodium hydroxide solution was added to quench the reaction. The pH was adjusted to 7, vacuum filtered, rotary evaporated, distilled water was added, and the mixture was stirred in an oil bath at 110°C. The mixture was cooled and freeze-dried to obtain product 1.

[0064] Q2: Add 3.77 g of product 1 to 10 mL of pyridine, stir to dissolve, and then slowly dropwise add 8 mL of toluene containing 1 g of chloroacetyl chloride in an ice bath at 3°C. After the addition is complete, react at room temperature for 8 h. After the reaction is complete, filter, evaporate under reduced pressure, and dry in vacuo to obtain product 2.

[0065] Q3: 6.4 g of polyethylene glycol monomethyl ether was added to a container, followed by the addition of 0.022 g of boron trifluoride etherate, and 1.3 mL of epichlorohydrin was slowly added dropwise, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure, and sodium hydroxide solution was slowly added dropwise, and the reaction was continued with stirring. After the reaction was completed, the mixture was distilled under reduced pressure, filtered, and added to a container containing 1.6 g of N,N'-dimethylethylenediamine, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure to obtain product 3;

[0066] Q4: Add 1.8 g of product 2 and 1.98 g of product 3 to a container containing 35 mL of N,N-dimethylformamide, then add 0.0189 g of potassium iodide, heat at 105°C, condense and reflux for 48 hours. After the reaction is completed, distill under reduced pressure, wash, and dry to obtain the main surfactant.

[0067] This embodiment discloses a method for preparing a cosurfactant, comprising the following steps:

[0068] S1: 12 g of p-anisidine was added to a container containing 100 mL of deionized water, and after stirring, 120 mL of a 2 mol / L hydrochloric acid aqueous solution was slowly added dropwise. After fully dissolved, the mixture was stirred in an ice bath at 0°C to obtain solution a. 7.8 g of sodium nitrite was added to a container containing 50 mL of deionized water, stirred to dissolve, and placed in an ice bath at 0°C to obtain solution b. Solution b was slowly added to solution a, and the mixture was stirred at 0°C for 60 minutes to obtain solution c. 5.02 g of sodium hydroxide, 12.4 g of sodium bicarbonate, and 50 mL of deionized water were mixed, and then 8.5 g of phenol was added. The mixture was placed in an ice bath at 0°C to obtain solution d. Solution c was slowly added to solution d. After the addition was completed, the mixture was stirred and reacted for 100 minutes. After the reaction was completed, the mixture was acidified, filtered, washed, and recrystallized to obtain intermediate A.

[0069] S2: 6 g of intermediate A, 7.82 g of ethyl 6-bromohexanoate, 0.172 g of potassium iodide, and 9.48 g of potassium carbonate were added to 150 mL of N,N-dimethylformamide. The mixture was heated at 85°C under argon protection for 8 h. After the reaction, the mixture was acidified, filtered, washed, and recrystallized to obtain intermediate B.

[0070] S3: 7.5 g of intermediate B was added to 300 mL of anhydrous ethanol, followed by 7.84 g of potassium hydroxide, stirred, heated at 80°C for 12 h, acidified, filtered, dried, and recrystallized to obtain intermediate C;

[0071] S4: 8 g of glycerol polyoxyethylene ether was added to a container, followed by 10.4 g of intermediate C and 0.046 g of p-toluenesulfonic acid. The mixture was stirred in an oil bath at 120° C. for 6 h. After the reaction was completed, the mixture was cooled and vacuum dried to obtain a co-surfactant.

[0072] This embodiment discloses a salt-resistant foaming agent for oilfield development, which is composed of the following ingredients in parts by weight: 25 parts of a main surfactant, 10 parts of cocamidopropyl betaine, 0.6 parts of a cosurfactant, 4 parts of disodium EDTA, 0.12 parts of nano-silicon dioxide, and 6 parts of isopropyl alcohol.

[0073] This embodiment discloses a method for preparing a salt-resistant foaming agent for oil field development, comprising the following steps:

[0074] Step 1: Add the main surfactant to the reactor, heat it, then slowly add cocamidopropyl betaine, continue stirring to obtain the main mixture;

[0075] Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silicon dioxide and isopropyl alcohol, stir and mix, let stand, filter, and homogenize to obtain a salt-resistant foaming agent for oil field development.

[0076] Example 4: This example discloses a method for preparing a primary surfactant, comprising the following steps:

[0077] Q1: 5.2 g of 1-dodecanol and 0.98 g of dodecylbenzenesulfonic acid were added to a container and mixed. 0.05 g of glucose was then added and heated at 100°C for 8 h. After the reaction, the temperature was lowered to 60°C and 1 mL of 5 wt% sodium hydroxide solution was added to quench the reaction. The pH was adjusted to 7, vacuum filtered, rotary evaporated, distilled water was added, and the mixture was stirred in an oil bath at 110°C. The mixture was cooled and freeze-dried to obtain product 1.

[0078] Q2: Add 2.48 g of product 1 to 10 mL of pyridine, stir to dissolve, and then slowly dropwise add 8 mL of toluene containing 1 g of chloroacetyl chloride in an ice bath at 3°C. After the addition is complete, react at room temperature for 8 h. After the reaction is complete, filter, evaporate under reduced pressure, and dry in vacuo to obtain product 2.

[0079] Q3: 3.8 g of polyethylene glycol monomethyl ether was added to a container, followed by 0.017 g of boron trifluoride etherate, and 1 mL of epichlorohydrin was slowly added dropwise, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure, and sodium hydroxide solution was slowly added dropwise, and the reaction was continued with stirring. After the reaction was completed, the mixture was distilled under reduced pressure, filtered, and added to a container containing 1.2 g of N,N'-dimethylethylenediamine, and the reaction was stirred. After the reaction was completed, the mixture was distilled under reduced pressure to obtain product 3;

[0080] Q4: Add 1.2 g of product 2 and 1.23 g of product 3 to a container containing 22.5 mL of N,N-dimethylformamide, then add 0.0165 g of potassium iodide, heat at 105°C, condense and reflux for 48 hours. After the reaction is completed, distill under reduced pressure, wash, and dry to obtain the main surfactant.

[0081] This embodiment discloses a method for preparing a cosurfactant, comprising the following steps:

[0082] S1: 10.5 g of p-anisidine was added to a container filled with 100 mL of deionized water, and after stirring evenly, 120 mL of a 2 mol / L hydrochloric acid aqueous solution was slowly added dropwise. After fully dissolved, the mixture was stirred in an ice bath at 0°C to obtain solution a. 7.1 g of sodium nitrite was added to a container filled with 50 mL of deionized water, stirred to dissolve, and placed in an ice bath at 0°C to obtain solution b. Solution b was slowly added to solution a, and the mixture was stirred at 0°C for 60 minutes to obtain solution c. 4.87 g of sodium hydroxide, 10.8 g of sodium bicarbonate, and 50 mL of deionized water were mixed, and then 7.2 g of phenol was added. The mixture was placed in an ice bath at 0°C to obtain solution d. Solution c was slowly added to solution d. After the addition was completed, the mixture was stirred and reacted for 100 minutes. After the reaction was completed, the mixture was acidified, filtered, washed, and recrystallized to obtain intermediate A.

[0083] S2: 5.2 g of intermediate A, 7.41 g of ethyl 6-bromohexanoate, 0.151 g of potassium iodide, and 9.12 g of potassium carbonate were added to 125 mL of N,N-dimethylformamide. The mixture was heated at 85°C under argon protection for 8 h. After the reaction, the mixture was acidified, filtered, washed, and recrystallized to obtain intermediate B.

[0084] S3: 5.5 g of intermediate B was added to 220 mL of anhydrous ethanol, followed by the addition of 6.51 g of potassium hydroxide, followed by stirring. The mixture was heated at 80°C for 12 h, acidified, filtered, dried, and recrystallized to obtain intermediate C.

[0085] S4: Add 9 g of glycerol polyoxyethylene ether to a container, then add 8.1 g of intermediate C and 0.032 g of p-toluenesulfonic acid, and stir in an oil bath at 120°C for 6 h. After the reaction is completed, cool and vacuum dry to obtain a co-surfactant.

[0086] This embodiment discloses a salt-resistant foaming agent for oilfield development, which is composed of the following ingredients in parts by weight: 21 parts of a primary surfactant, 6 parts of cocamidopropyl betaine, 0.2 parts of a cosurfactant, 2 parts of disodium EDTA, 0.06 parts of nano-silicon dioxide, and 4 parts of isopropyl alcohol.

[0087] This embodiment discloses a method for preparing a salt-resistant foaming agent for oil field development, comprising the following steps:

[0088] Step 1: Add the main surfactant to the reactor, heat it, then slowly add cocamidopropyl betaine, continue stirring to obtain the main mixture;

[0089] Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silicon dioxide and isopropyl alcohol, stir and mix, let stand, filter, and homogenize to obtain a salt-resistant foaming agent for oil field development.

[0090] Comparative Example 1: Compared with Example 1, in Comparative Example 1, during the preparation of the salt-resistant foaming agent for oil field development, no main surfactant is added, and other conditions remain unchanged.

[0091] Comparative Example 2: Compared with Example 1, in Comparative Example 2, no co-surfactant is added during the preparation of the salt-resistant foaming agent for oil field development, and other conditions remain unchanged.

[0092] Experimental Example: The performance of the salt-resistant foaming agent for oil field development prepared in Examples 1-4 and Comparative Examples 1-2 was tested. The samples were placed at different temperatures and different salt concentrations, and the foam half-life and liquid carrying capacity of the samples were tested according to SY / T 7494-2020. The test results are shown in Tables 1 and 2:

[0093] Table 1

[0094]

[0095] As can be seen from the test results in Table 1, the salt-resistant foaming agents for oil field development prepared in Examples 1-4 of the present invention have excellent stability. A comparison between Comparative Example 1 and Examples 1-4 shows that the use of a primary surfactant can effectively improve the stability of the foaming agent; a comparison between Comparative Example 2 and Examples 1-4 shows that the use of a co-surfactant can effectively improve the stability of the foaming agent.

[0096] Table 2

[0097]

[0098] As can be seen from the test results in Table 2, the salt-resistant foaming agents for oil field development prepared in Examples 1-4 of the present invention have excellent salt resistance. A comparison between Comparative Example 1 and Examples 1-4 shows that the use of a primary surfactant can effectively improve the salt resistance of the foaming agent; a comparison between Comparative Example 2 and Examples 1-4 shows that the use of a co-surfactant can effectively improve the salt resistance of the foaming agent.

[0099] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

[0100] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A salt-resistant foaming agent for oil field development, characterized in that: The invention is composed of the following ingredients in parts by weight: 15-25 parts of a main surfactant, 5-10 parts of cocamidopropyl betaine, 0.1-0.6 parts of a cosurfactant, 1-4 parts of disodium EDTA, 0.05-0.12 parts of nano-silicon dioxide, and 3-6 parts of isopropyl alcohol; The preparation method of the main surfactant comprises the following steps: Q1: 1-dodecanol and dodecylbenzenesulfonic acid were added to a container, mixed and stirred, and then glucose was added and heated for reaction. After the reaction was completed, the temperature was lowered, and sodium hydroxide solution was added to quench the reaction. The pH was adjusted, vacuum filtered, rotary evaporated, distilled water was added, and the mixture was stirred in an oil bath, cooled, and freeze-dried to obtain product 1; Q2: Add product 1 to pyridine, stir to dissolve, and then slowly dropwise add toluene containing chloroacetyl chloride in an ice bath. After the addition is complete, react at room temperature. After the reaction is complete, filter, distill under reduced pressure, and dry in vacuo to obtain product 2. Q3: Add polyethylene glycol monomethyl ether to a container, then add boron trifluoride ether complex, slowly add epichlorohydrin dropwise, stir to react, and after the reaction is completed, distill under reduced pressure, slowly add sodium hydroxide solution dropwise, continue to stir to react, and after the reaction is completed, distill under reduced pressure, filter, add to a container containing N,N'-dimethylethylenediamine, stir to react, and after the reaction is completed, distill under reduced pressure to obtain product 3; Q4: Add product 2 and product 3 to a container containing N,N-dimethylformamide, then add potassium iodide, heat, condense and reflux to react. After the reaction is completed, distill under reduced pressure, wash and dry to obtain the main surfactant; The preparation method of the cosurfactant comprises the following steps: S1: Add p-methoxyaniline to a container filled with deionized water, stir evenly, slowly add aqueous hydrochloric acid solution dropwise, fully dissolve, and stir in an ice bath to obtain solution a; add sodium nitrite to a container filled with deionized water, stir and dissolve, and place in an ice bath to obtain solution b; slowly add solution b to solution a, stir and react at low temperature to obtain solution c; mix sodium hydroxide, sodium bicarbonate and deionized water, then add phenol, and place in an ice bath to obtain solution d; slowly add solution c to solution d, continue stirring and reacting after the addition is complete, and after the reaction is completed, acidify, filter, wash, and recrystallize to obtain intermediate A; S2: Add intermediate A, ethyl 6-bromohexanoate, potassium iodide, and potassium carbonate to N,N-dimethylformamide, and heat under argon protection to react. After the reaction is completed, acidify, filter, wash, and recrystallize to obtain intermediate B; S3: adding intermediate B to anhydrous ethanol, then adding potassium hydroxide and stirring, heating for reaction, acidifying, filtering, drying, and recrystallizing to obtain intermediate C; S4: Add glycerol polyoxyethylene ether to a container, then add intermediate C and p-toluenesulfonic acid, and react by stirring in an oil bath. After the reaction is completed, cool and vacuum dry to obtain a co-surfactant.

2. The salt-resistant foaming agent for oil field development according to claim 1, characterized in that: In the Q1, the molar ratio of 1-dodecanol, dodecylbenzenesulfonic acid and glucose is (4-7): (0.9-1.2): (0.03-0.05); in the Q2, the molar ratio of product 1 and chloroacetyl chloride is (0.9-1.2): (0.98-1.45).

3. The salt-resistant foaming agent for oil field development according to claim 1, characterized in that: In the Q3, the usage ratio of polyethylene glycol monomethyl ether, boron trifluoride ethyl ether complex, epichlorohydrin and N,N'-dimethylethylenediamine is (3-6.4) g: (0.015-0.022) g: (0.9-1.3) mL: (1.1-1.6) g.

4. The salt-resistant foaming agent for oil field development according to claim 1, characterized in that: In Q4, the usage ratio of product 2, product 3, N,N-dimethylformamide and potassium iodide is (1-1.8) g: (1.12-1.98) g: (20-35) mL: (0.016-0.0189) g.

5. The salt-resistant foaming agent for oil field development according to claim 1, characterized in that: In S1, the usage ratio of p-anisidine, sodium nitrite, sodium hydroxide, sodium bicarbonate and phenol is (10-12) g: (6.7-7.8) g: (4.82-5.02) g: (10.1-12.4) g: (7-8.5) g; in S2, the usage ratio of intermediate A, ethyl 6-bromohexanoate, potassium iodide, potassium carbonate and N,N-dimethylformamide is (5-6) g: (7.33-7.82) g: (0.145-0.172) g: (9.01-9.48) g: (120-150) mL.

6. The salt-resistant foaming agent for oil field development according to claim 1, characterized in that: In the S3, the usage ratio of the intermediate B, anhydrous ethanol, and potassium hydroxide is (5-7.5) g: (200-300) mL: (6.01-7.84) g; in the S4, the usage ratio of glycerol polyoxyethylene ether, intermediate C, and p-toluenesulfonic acid is (8-12) g: (7-10.4) g: (0.03-0.046) g.

7. The method for preparing a salt-resistant foaming agent for oil field development according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Add the main surfactant to the reactor, heat it, then slowly add cocamidopropyl betaine, continue stirring to obtain the main mixture; Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silicon dioxide and isopropyl alcohol, stir and mix, let stand, filter, and homogenize to obtain a salt-resistant foaming agent for oil field development.

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