Salt-resistant foam scrubbing agent for oilfield exploitation and preparation method thereof

Abstract

The invention discloses a salt-resistant foam scrubbing agent for oilfield exploitation and a preparation method thereof, and belongs to the technical field of foam scrubbing agent preparation. The salt-resistant foam scrubbing agent for oilfield exploitation is prepared from the following components in parts by weight: 15 to 25 parts of a main surfactant, 5 to 10 parts of cocamidopropyl betaine, 0.1 to 0.6 part of a cosurfactant, 1 to 4 parts of EDTA (Ethylene Diamine Tetraacetic Acid) disodium, 0.05 to 0.12 part of nano silicon dioxide and 3 to 6 parts of isopropanol. The foam scrubbing agent prepared by the invention has excellent salt resistance and stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of foam drainage agent preparation, and particularly relates to an anti-salt foam drainage agent for oilfield development and a preparation method thereof. Background Art

[0002] In the process of oil and gas field development, gas well liquid accumulation is one of the key problems restricting the stable production of low-permeability and low-pressure gas wells. As the gas field development enters the middle and late stages, the formation energy gradually declines, and the bottom hole liquid accumulation significantly increases, resulting in a sharp decline in the gas well production capacity or even shut-down. As an economic and efficient liquid drainage method, the core of the foam drainage gas production technology is to form a low-density foam system in the wellbore through a foam drainage agent, and use the characteristics of gas-liquid two-phase flow to carry the liquid accumulation to the ground. However, the application limitations of traditional foam drainage agents in complex oil and gas reservoir environments are becoming increasingly prominent. Especially under high-temperature, high-salinity and long-term production conditions, the insufficient foaming performance, salt resistance and stability have become the core bottlenecks restricting the technical effectiveness.

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

[0004] The purpose of the present invention is to provide an anti-salt foam drainage agent for oilfield development and a preparation method thereof, which are used to solve the technical problem of poor stability and salt tolerance of the foam drainage agent in the prior art.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions: The present invention provides an anti-salt foam drainage agent for oilfield development, which is composed of the following components in parts by weight: 15-25 parts of main surfactant, 5-10 parts of cocamidopropyl betaine, 0.1-0.6 parts of co-surfactant, 1-4 parts of disodium EDTA, 0.05-0.12 parts of nano-silica, and 3-6 parts of isopropanol.

[0006] Preferably, the preparation method of the main surfactant includes the following steps: Q1: Add 1-dodecanol and dodecylbenzenesulfonic acid into a container, mix and stir, then add glucose, heat for reaction. After the reaction is completed, cool down, add sodium hydroxide solution to quench the reaction, adjust the pH, perform vacuum filtration, rotary evaporation, add distilled water and stir in an oil bath, cool, and freeze-dry to obtain Product 1; Q2: Add Product 1 into pyridine, stir to dissolve it, and slowly add toluene containing chloroacetyl chloride in an ice bath environment. After the addition is completed, react at room temperature. After the reaction is completed, perform suction filtration, distill under reduced pressure, and dry under vacuum to obtain Product 2; Q3: Add polyethylene glycol monomethyl ether into a container, then add boron trifluoride diethyl ether complex, slowly add epichlorohydrin, stir for reaction. After the reaction is completed, distill under reduced pressure, slowly add sodium hydroxide solution, continue to stir for reaction. After the reaction is completed, distill under reduced pressure, perform suction filtration, add it to a container containing N,N'-dimethylethylenediamine, stir for reaction. After the reaction is completed, distill under reduced pressure to obtain Product 3; Q4: Add Product 2 and Product 3 into a container containing N,N-dimethylformamide, then add potassium iodide, heat for reflux condensation reaction. After the reaction is completed, distill under reduced pressure, wash, and dry to obtain the main surfactant.

[0007] In the above process, dodecylbenzenesulfonic acid provides hydrogen ions to activate the anomeric carbon hydroxyl group of glucose. Subsequently, the hydroxyl group of 1-dodecanol attacks the activated carbon as a nucleophile, and a nucleophilic substitution reaction occurs to obtain Product 1; then the hydroxyl group in Product 1 reacts with the acyl chloride group in chloroacetyl chloride to obtain Product 2; subsequently, the hydroxyl group in polyethylene glycol monomethyl ether reacts with the chlorine group in epichlorohydrin, and then continues to react with N,N'-dimethylethylenediamine to undergo an epoxy ring-opening reaction to obtain Product 3; finally, Product 2 and Product 3 undergo a quaternization reaction to obtain the main surfactant.

[0008] 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 - 9 h, cool down to 55 - 65 °C, adjust the pH = 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 room temperature reaction time is 6 - 8 h.

[0009] Preferably, in Q3, the dosage ratio of polyethylene glycol monomethyl ether, boron trifluoride diethyl 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.

[0010] 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 and condensation reflux reaction temperature is 100 - 110 °C, and the reaction time is 48 - 52 h.

[0011] Preferably, the preparation method of the co-surfactant comprises the following steps: S1: Add p-methoxyaniline to a container filled with deionized water. After stirring evenly, slowly add hydrochloric acid aqueous solution. After complete dissolution, stir in an ice bath to obtain solution a. Add sodium nitrite to a container filled with deionized water, stir to dissolve, and place it in an ice bath environment 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, then add phenol, and place it in an ice bath environment to obtain solution d. Slowly add solution c to solution d. After the addition, continue to stir and react. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate A; S2: Add intermediate A, ethyl 6-bromohexanoate, potassium iodide and potassium carbonate to N,N-dimethylformamide. Under argon protection, heat and react. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate B; S3: Add intermediate B to absolute ethanol, then add potassium hydroxide and stir. After heating and reacting, acidify, filter by suction, dry, and recrystallize to obtain intermediate C; S4: Add glycerol polyoxyethylene ether to a container, then add intermediate C and p-toluenesulfonic acid, and stir and react in an oil bath. After the reaction is completed, cool and dry under vacuum to obtain the co-surfactant.

[0012] In the above process, the synthesis reaction formula of the co-surfactant is as follows:

[0013] The mass spectrometry analysis results of intermediate A are: m / z: 228.09 (100.0%), 229.09 (14.9%); the mass spectrometry analysis results of intermediate B are: m / z: 370.19 (100.0%), 371.19 (23.6%), 372.20 (2.6%), 372.19(1.0%); the mass spectrometry analysis results of intermediate C are: m / z: 342.16 (100.0%), 343.16 (21.0%), 344.16(3.0%).

[0014] Preferably, in S1, the dosage ratio of p - methoxyaniline, 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 dosage 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.

[0015] Preferably, in S3, the dosage ratio of intermediate B, absolute 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 dosage 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.

[0016] Preferably, a preparation method of a salt - resistant foam - discharging agent for oilfield exploitation includes the following steps: Step 1: Add the main surfactant into a reaction kettle, raise the temperature, and then slowly add cocoamidopropyl betaine, and continue stirring to obtain a main mixture; Step 2: Add the co - surfactant into the main mixture, then slowly add disodium EDTA, nano - silicon dioxide and isopropanol, stir and mix, stand, filter, and perform homogenization treatment to obtain the salt - resistant foam - discharging agent for oilfield exploitation.

[0017] In summary, due to the adoption of the above - mentioned technical solution, the beneficial effects of the present invention are as follows: 1. By adding the prepared main surfactant and co - surfactant into the preparation process of the foam - discharging agent, the stability and salt resistance of the foam - discharging agent can be effectively improved.

[0018] 2. The main surfactant prepared in the present invention is used as one of the main components of the foam drainage agent, which can effectively improve the stability and salt resistance of the foam drainage agent. The quaternary ammonium salt structure contained in the main surfactant carries a positive charge and combines with high-valent metal ions such as calcium and magnesium in formation water through the charge shielding effect to avoid salting out. The ether oxygen atoms contained can form hydrogen bonds with water molecules, and the long-chain steric hindrance prevents salt ions from approaching the polar head of the surfactant, reducing salt sensitivity. Moreover, the formed dynamic hydrogen bond network can enhance the hydration stability of the surfactant in a high-salt environment. The hydrophobic tail and flexible hydrophilic chain contained in the main surfactant can jointly adsorb on the gas-liquid interface to form an interfacial film. The quaternary ammonium salt structure enhances the mechanical strength of the film and resists the 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 liquid drainage and gas diffusion.

[0019] 3. The co-surfactant prepared in the present invention is used as one of the main components of the foam drainage agent, which can effectively improve the stability and salt resistance of the foam drainage agent. The polyoxyethylene chain contained in the co-surfactant forms a hydration layer, hindering the approach of high-valent ions to the polar head of the surfactant and reducing salting-out precipitation. The rigid azobenzene structure contained can prevent salt-induced molecular curling and improve the salt resistance of the foam drainage agent. The hydrophobic azobenzene group contained can co-adsorb on the gas-liquid interface with the polyoxyethylene chain to form a dense and elastic interfacial film, resisting the destruction of salt ions and thus improving the stability. Detailed implementation manners

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] Example 1: This example discloses a preparation method of a main surfactant, including the following steps: Q1: Add 5.5 g of 1-dodecanol and 1.03 g of dodecylbenzenesulfonic acid into a container, mix and stir, then add 0.04 g of glucose, heat and react at 100 °C for 8 h. After the reaction is completed, cool down to 60 °C, add 1 mL of sodium hydroxide solution with a mass fraction of 5 wt% to quench the reaction, adjust the pH = 7, perform vacuum filtration, rotary evaporation, add distilled water and carry out oil bath stirring at 110 °C, cool, and freeze-dry to obtain Product 1; Q2: Add 2.84 g of Product 1 into 10 mL of pyridine, stir to dissolve, and slowly dropwise add 8 mL of toluene containing 1 g of chloroacetyl chloride in an ice bath environment at 3 °C. After the addition is completed, react at room temperature for 8 h. After the reaction is completed, perform suction filtration, distillation under reduced pressure, and vacuum drying to obtain Product 2; Q3: Add 4.7 g of methoxypolyethylene glycol to a container, then add 0.018 g of boron trifluoride ether complex, slowly dropwise add 1.1 mL of epichlorohydrin, stir and react. After the reaction is completed, distill under reduced pressure, slowly dropwise add sodium hydroxide solution, continue to stir and react. After the reaction is completed, distill under reduced pressure, filter by suction, add to a container containing 1.35 g of N,N'-dimethylethylenediamine, stir and react. After the reaction is completed, distill under reduced pressure to obtain product 3; 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 and reflux at 105 °C for 48 h, distill under reduced pressure after the reaction is completed, wash, and dry to obtain the main surfactant.

[0022] This example discloses a preparation method of a co-surfactant, including the following steps: S1: Add 11 g of p-methoxyaniline to a container containing 100 mL of deionized water, stir evenly, then slowly dropwise add 120 mL of hydrochloric acid aqueous solution with a concentration of 2 mol / L. After complete dissolution, stir in an ice bath at 0 °C to obtain solution a. Add 7.2 g of sodium nitrite to a container containing 50 mL of deionized water, stir and dissolve, place in an ice bath environment at 0 °C to obtain solution b. Slowly add solution b to solution a, stir and react at 0 °C for 60 min to obtain solution c. Mix 4.92 g of sodium hydroxide, 11.2 g of sodium bicarbonate and 50 mL of deionized water, then add 7.7 g of phenol, place in an ice bath environment at 0 °C to obtain solution d. Slowly add solution c to solution d, after addition, continue to stir and react for 100 min. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate A; S2: Add 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 to 135 mL of N,N-dimethylformamide, heat and react at 85 °C for 8 h under argon protection. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate B; S3: Add 6.25 g of intermediate B to 250 mL of absolute ethanol, then add 6.92 g of potassium hydroxide and stir. Heat and react at 80 °C for 12 h, acidify, filter by suction, dry, and recrystallize to obtain intermediate C; 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, stir and react in an oil bath at 120 °C for 6 h. After the reaction is completed, cool and dry under vacuum to obtain the co-surfactant.

[0023] This embodiment discloses an anti-salt foam drainage agent for oilfield development, which is composed of the following components by weight: 20 parts of main surfactant, 7.5 parts of cocamidopropyl betaine, 0.35 part of co-surfactant, 2.5 parts of disodium EDTA, 0.08 part of nano-silica, and 4.5 parts of isopropanol.

[0024] This embodiment discloses a preparation method of an anti-salt foam drainage agent for oilfield development, including the following steps: Step 1: Add the main surfactant to the reaction kettle, heat up, and then slowly add cocamidopropyl betaine, and continue to stir to obtain the main mixture; Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silica, and isopropanol, stir and mix, stand still, filter, and perform homogenization treatment to obtain the anti-salt foam drainage agent for oilfield development.

[0025] Example 2: This embodiment discloses a preparation method of a main surfactant, including the following steps: Q1: Add 5 g of 1-dodecanol and 0.92 g of dodecylbenzenesulfonic acid to a container, mix and stir, then add 0.06 g of glucose, heat and react at 100 °C for 8 h. After the reaction is completed, cool down to 60 °C, add 1 mL of sodium hydroxide solution with a mass fraction of 5 wt% to quench the reaction, adjust the pH = 7, perform vacuum filtration, rotary evaporation, add distilled water and perform oil bath stirring at 110 °C, cool, and freeze-dry to obtain Product 1; Q2: Add 1.91 g of Product 1 to 10 mL of pyridine, stir to dissolve, and slowly dropwise add 8 mL of toluene containing 1 g of chloroacetyl chloride in an ice bath environment at 3 °C. After the addition is completed, react at room temperature for 8 h. After the reaction is completed, perform suction filtration, vacuum distillation, and vacuum drying to obtain Product 2; Q3: Add 3 g of polyethylene glycol monomethyl ether to a container, then add 0.015 g of boron trifluoride diethyl ether complex, slowly dropwise add 0.9 mL of epichlorohydrin, stir and react. After the reaction is completed, perform vacuum distillation, slowly dropwise add sodium hydroxide solution, continue to stir and react. After the reaction is completed, perform vacuum distillation, suction filtration, add it to a container containing 1.1 g of N,N'-dimethylethylenediamine, stir and react. After the reaction is completed, perform vacuum distillation to obtain Product 3; 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 and perform condensation reflux reaction at 105 °C for 48 h. After the reaction is completed, perform vacuum distillation, washing, and drying to obtain the main surfactant.

[0026] This embodiment discloses a preparation method of a co-surfactant, including the following steps: S1: Add 10 g of p-methoxyaniline to a container filled with 100 mL of deionized water. After stirring evenly, slowly add 120 mL of a hydrochloric acid aqueous solution with a concentration of 2 mol / L. After complete dissolution, stir in an ice bath at 0 °C to obtain solution a. Add 6.7 g of sodium nitrite to a container filled with 50 mL of deionized water, stir to dissolve, and place it in an ice bath environment at 0 °C to obtain solution b. Slowly add solution b to solution a, and stir and react at 0 °C for 60 min to obtain solution c. Mix 4.82 g of sodium hydroxide, 10.1 g of sodium bicarbonate, and 50 mL of deionized water, then add 7 g of phenol, and place it in an ice bath environment at 0 °C to obtain solution d. Slowly add solution c to solution d. After the addition, continue to stir and react for 100 min. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate A; S2: Add 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 to 120 mL of N,N-dimethylformamide. Under argon protection, heat and react at 85 °C for 8 h. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate B; S3: Add 5 g of intermediate B to 200 mL of absolute ethanol, then add 6.01 g of potassium hydroxide and stir. Heat and react at 80 °C for 12 h, then acidify, filter by suction, dry, and recrystallize to obtain intermediate C; 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 and react in an oil bath at 120 °C for 6 h. After the reaction is completed, cool and dry under vacuum to obtain the co-surfactant.

[0027] This example discloses an anti-salt foam drainage agent for oilfield development, which is composed of the following components by weight: 15 parts of main surfactant, 5 parts of cocamidopropyl betaine, 0.1 part of co-surfactant, 1 part of disodium EDTA, 0.05 part of nano-silica, and 3 parts of isopropanol.

[0028] This example discloses a preparation method of an anti-salt foam drainage agent for oilfield development, including the following steps: Step 1: Add the main surfactant to the reaction kettle, raise the temperature, and then slowly add cocamidopropyl betaine, and continue to stir to obtain the main mixture; Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silica, and isopropanol. After stirring and mixing, let it stand, filter, and perform homogenization treatment to obtain the anti-salt foam drainage agent for oilfield development.

[0029] Example 3: This example discloses a preparation method of a main surfactant, including the following steps: Q1: Add 6 g of 1-dodecanol and 1.17 g of dodecylbenzenesulfonic acid into a container, mix and stir, then add 0.02 g of glucose, heat and react at 100 °C for 8 h. After the reaction is completed, cool down to 60 °C, add 1 mL of sodium hydroxide solution with a mass fraction of 5 wt% to quench the reaction, adjust the pH to 7, perform vacuum filtration, rotary evaporation, add distilled water, carry out oil bath stirring at 110 °C, cool, and freeze-dry to obtain Product 1; Q2: Add 3.77 g of Product 1 into 10 mL of pyridine, stir to dissolve, and slowly add 8 mL of toluene containing 1 g of chloroacetyl chloride under an ice bath environment at 3 °C. After the addition is completed, react at room temperature for 8 h. After the reaction is completed, carry out suction filtration, distillation under reduced pressure, and vacuum drying to obtain Product 2; Q3: Add 6.4 g of polyethylene glycol monomethyl ether into a container, then add 0.022 g of boron trifluoride diethyl ether complex, slowly add 1.3 mL of epichlorohydrin, stir and react. After the reaction is completed, carry out distillation under reduced pressure, slowly add sodium hydroxide solution, continue to stir and react. After the reaction is completed, carry out distillation under reduced pressure, suction filtration, add it into a container containing 1.6 g of N,N'-dimethylethylenediamine, stir and react. After the reaction is completed, carry out distillation under reduced pressure to obtain Product 3; Q4: Add 1.8 g of Product 2 and 1.98 g of Product 3 into a container containing 35 mL of N,N-dimethylformamide, then add 0.0189 g of potassium iodide, heat and carry out reflux condensation reaction at 105 °C for 48 h. After the reaction is completed, carry out distillation under reduced pressure, washing, and drying to obtain the main surfactant.

[0030] This example discloses a preparation method of a co-surfactant, including the following steps: S1: Add 12 g of p-methoxyaniline into a container containing 100 mL of deionized water, stir evenly, then slowly add 120 mL of hydrochloric acid aqueous solution with a concentration of 2 mol / L. After fully dissolving, carry out ice bath stirring at 0 °C to obtain Solution a. Add 7.8 g of sodium nitrite into a container containing 50 mL of deionized water, stir to dissolve, and place it in an ice bath environment at 0 °C to obtain Solution b. Slowly add Solution b into Solution a, stir and react at 0 °C for 60 min to obtain Solution c. Mix 5.02 g of sodium hydroxide, 12.4 g of sodium bicarbonate and 50 mL of deionized water, then add 8.5 g of phenol, and place it in an ice bath environment at 0 °C to obtain Solution d. Slowly add Solution c into Solution d. After the addition is completed, continue to stir and react for 100 min. After the reaction is completed, acidify, carry out suction filtration, washing, and recrystallization to obtain Intermediate A; S2: Add 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 into 150 mL of N,N-dimethylformamide, heat and react at 85 °C for 8 h under argon protection. After the reaction is completed, acidify, carry out suction filtration, washing, and recrystallization to obtain Intermediate B; S3: Add 7.5 g of intermediate B to 300 mL of absolute ethanol, then add 7.84 g of potassium hydroxide and stir. After heating and reacting at 80 °C for 12 h, acidify, filter by suction, dry, and recrystallize to obtain intermediate C; S4: Add 8 g of glycerol polyoxyethylene ether to a container, then add 10.4 g of intermediate C and 0.046 g of p-toluenesulfonic acid, and stir and react in an oil bath at 120 °C for 6 h. After the reaction is completed, cool and dry under vacuum to obtain the co-surfactant.

[0031] This example discloses an anti-salt foam drainage agent for oilfield development, which is composed of the following components in parts by weight: 25 parts of main surfactant, 10 parts of cocamidopropyl betaine, 0.6 part of co-surfactant, 4 parts of disodium EDTA, 0.12 part of nano-silica, and 6 parts of isopropanol.

[0032] This example discloses a preparation method of an anti-salt foam drainage agent for oilfield development, including the following steps: Step 1: Add the main surfactant to a reaction kettle, raise the temperature, and then slowly add cocamidopropyl betaine, and continue to stir to obtain the main mixture; Step 2: Add the co-surfactant to the main mixture, then slowly add disodium EDTA, nano-silica, and isopropanol. After stirring and mixing, let it stand, filter, and perform homogenization treatment to obtain the anti-salt foam drainage agent for oilfield development.

[0033] Example 4: This example discloses a preparation method of a main surfactant, including the following steps: Q1: Add 5.2 g of 1-dodecanol and 0.98 g of dodecylbenzenesulfonic acid to a container, mix and stir, then add 0.05 g of glucose, heat and react at 100 °C for 8 h. After the reaction is completed, cool to 60 °C, add 1 mL of sodium hydroxide solution with a mass fraction of 5 wt% to quench the reaction, adjust the pH = 7, filter by vacuum suction, perform rotary evaporation, add distilled water and stir in an oil bath at 110 °C, cool, and freeze-dry to obtain product 1; Q2: Add 2.48 g of product 1 to 10 mL of pyridine, stir to dissolve, and slowly add 8 mL of toluene containing 1 g of chloroacetyl chloride in an ice bath at 3 °C. After the addition is completed, react at room temperature for 8 h. After the reaction is completed, filter by suction, distill under reduced pressure, and dry under vacuum to obtain product 2; Q3: Add 3.8 g of methoxypolyethylene glycol to a container, then add 0.017 g of boron trifluoride diethyl ether complex, slowly add 1 mL of epichlorohydrin, stir and react. After the reaction is completed, distill under reduced pressure, slowly add sodium hydroxide solution, and continue to stir and react. After the reaction is completed, distill under reduced pressure, filter by suction, add to a container containing 1.2 g of N,N'-dimethylethylenediamine, stir and react. After the reaction is completed, distill under reduced pressure to obtain product 3; Q4: Add 1.2 g of product 2 and 1.23 g of product 3 into a container containing 22.5 mL of N,N-dimethylformamide, then add 0.0165 g of potassium iodide, and heat under reflux at 105 °C for 48 h. After the reaction is completed, perform vacuum distillation, washing, and drying to obtain the main surfactant.

[0034] This example discloses a preparation method of a co-surfactant, which includes the following steps: S1: Add 10.5 g of p-methoxyaniline into a container containing 100 mL of deionized water. After stirring evenly, slowly dropwise add 120 mL of hydrochloric acid aqueous solution with a concentration of 2 mol / L. After complete dissolution, stir in an ice bath at 0 °C to obtain solution a. Add 7.1 g of sodium nitrite into a container containing 50 mL of deionized water, stir to dissolve, and place it in an ice bath environment at 0 °C to obtain solution b. Slowly add solution b into solution a, and stir and react at 0 °C for 60 min to obtain solution c. Mix 4.87 g of sodium hydroxide, 10.8 g of sodium bicarbonate, and 50 mL of deionized water, then add 7.2 g of phenol, and place it in an ice bath environment at 0 °C to obtain solution d. Slowly add solution c into solution d. After the addition is completed, continue to stir and react for 100 min. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate A; S2: Add 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 into 125 mL of N,N-dimethylformamide. Under argon protection, heat and react at 85 °C for 8 h. After the reaction is completed, acidify, filter by suction, wash, and recrystallize to obtain intermediate B; S3: Add 5.5 g of intermediate B into 220 mL of absolute ethanol, then add 6.51 g of potassium hydroxide and stir. Heat and react at 80 °C for 12 h, then acidify, filter by suction, dry, and recrystallize to obtain intermediate C; S4: Add 9 g of glycerol polyoxyethylene ether into a container, then add 8.1 g of intermediate C and 0.032 g of p-toluenesulfonic acid, and stir and react in an oil bath at 120 °C for 6 h. After the reaction is completed, cool and perform vacuum drying to obtain the co-surfactant.

[0035] This example discloses an anti-salt foam drainage agent for oilfield development, which is composed of the following components in parts by weight: 21 parts of main surfactant, 6 parts of cocamidopropyl betaine, 0.2 part of co-surfactant, 2 parts of disodium EDTA, 0.06 part of nano-silica, and 4 parts of isopropanol.

[0036] This example discloses a preparation method of an anti-salt foam drainage agent for oilfield development, which includes the following steps: Step 1: Add the main surfactant into the reaction kettle, heat up, and then slowly add cocamidopropyl betaine, and continue stirring to obtain the main mixture. Step 2: Add the co-surfactant into the main mixture, then slowly add disodium EDTA, nano-silica, and isopropanol. After stirring and mixing, let it stand, filter, and perform homogenization treatment to obtain an anti-salt foam drainage agent for oilfield exploitation.

[0037] Comparative Example 1: Compared with Example 1, in the process of preparing the anti-salt foam drainage agent for oilfield exploitation in Comparative Example 1, the main surfactant is not added, and other conditions remain unchanged.

[0038] Comparative Example 2: Compared with Example 1, in the process of preparing the anti-salt foam drainage agent for oilfield exploitation in Comparative Example 2, the co-surfactant is not added, and other conditions remain unchanged.

[0039] Experimental Example: Test the performance of the anti-salt foam drainage agents for oilfield exploitation prepared in Examples 1-4 and Comparative Examples 1-2. Place the samples at different temperatures and different salt concentrations, and test the foam half-life and liquid-carrying capacity of the samples according to SY / T 7494-2020. The test results are shown in Table 1 and Table 2: Table 1

[0040] As can be seen from the test results in Table 1, the anti-salt foam drainage agents for oilfield exploitation prepared in Examples 1-4 of the present invention have excellent stability. By comparing Comparative Example 1 with Examples 1-4, it can be seen that the use of the main surfactant can effectively improve the stability of the foam drainage agent; by comparing Comparative Example 2 with Examples 1-4, it can be seen that the use of the co-surfactant can effectively improve the stability of the foam drainage agent.

[0041] Table 2

[0042] As can be seen from the test results in Table 2, the anti-salt foam drainage agents for oilfield exploitation prepared in Examples 1-4 of the present invention have excellent salt resistance. By comparing Comparative Example 1 with Examples 1-4, it can be seen that the use of the main surfactant can effectively improve the salt resistance of the foam drainage agent; by comparing Comparative Example 2 with Examples 1-4, it can be seen that the use of the co-surfactant can effectively improve the salt resistance of the foam drainage agent.

[0043] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

[0044] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific embodiments. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An anti-salt foam drainage aid for oilfield production, characterized in that, It consists of the following components in parts by weight: 15 - 25 parts of main surfactant, 5 - 10 parts of cocamidopropyl betaine, 0.1 - 0.6 part of cosurfactant, 1 - 4 parts of disodium EDTA, 0.05 - 0.12 part of nano - silica, and 3 - 6 parts of isopropanol.

2. The salt-resistant foam drainage aid for oilfield development according to claim 1, characterized in that The preparation method of the main surfactant includes the following steps: Q1: Add 1 - dodecanol and dodecylbenzenesulfonic acid into a container, mix and stir, then add glucose, heat for reaction. After the reaction is completed, cool down, add sodium hydroxide solution to quench the reaction, adjust the pH, carry out vacuum filtration, rotary evaporation, add distilled water for oil - bath stirring, cool, and freeze - dry to obtain Product 1; Q2: Add Product 1 into pyridine, stir to dissolve it, and then slowly add toluene containing chloroacetyl chloride under an ice - bath environment. After the addition is completed, react at room temperature. After the reaction is completed, carry out suction filtration, distill under reduced pressure, and vacuum - dry to obtain Product 2; Q3: Add polyethylene glycol monomethyl ether into a container, then add boron trifluoride diethyl ether complex, slowly add epichlorohydrin, stir for reaction. After the reaction is completed, distill under reduced pressure, slowly add sodium hydroxide solution, continue to stir for reaction. After the reaction is completed, distill under reduced pressure, carry out suction filtration, add it to a container containing N,N’ - dimethylethylenediamine, stir for reaction. After the reaction is completed, distill under reduced pressure to obtain Product 3; Q4: Add Product 2 and Product 3 into a container containing N,N - dimethylformamide, then add potassium iodide, heat for condensation reflux reaction. After the reaction is completed, distill under reduced pressure, wash, and dry to obtain the main surfactant.

3. The salt-resistant foam drainage aid for oilfield exploitation according to claim 2, characterized in that, In Q1, the molar ratio of 1 - dodecanol, dodecylbenzenesulfonic acid and glucose is (4 - 7):(0.9 - 1.2):(0.03 - 0.05); in Q2, the molar ratio of Product 1 and chloroacetyl chloride is (0.9 - 1.2):(0.98 - 1.45).

4. The anti-salt foam drainage aid for oilfield exploitation according to claim 2, characterized in that, In Q3, the dosage ratio of polyethylene glycol monomethyl ether, boron trifluoride diethyl 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.

5. The anti-salt foam drainage aid for oilfield exploitation according to claim 2, characterized in that, 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.

6. The anti-salt foam drainage aid for oilfield development according to claim 1, wherein The preparation method of the cosurfactant includes the following steps: S1: Add p-methoxyaniline into a container filled with deionized water. After stirring evenly, slowly dropwise add aqueous hydrochloric acid solution. After complete dissolution, stir in an ice bath to obtain solution a. Add sodium nitrite into a container filled with deionized water, stir to dissolve, and place it in an ice bath environment to obtain solution b. Slowly add solution b into solution a, stir and react to obtain solution c. Mix sodium hydroxide, sodium bicarbonate and deionized water, then add phenol, and place it in an ice bath environment to obtain solution d. Slowly add solution c into solution d. After addition, continue to stir and react. After the reaction ends, acidify, filter by suction, wash, and recrystallize to obtain intermediate A; S2: Add intermediate A, ethyl 6-bromohexanoate, potassium iodide and potassium carbonate into N,N-dimethylformamide. Under argon protection, heat and react. After the reaction ends, acidify, filter by suction, wash, and recrystallize to obtain intermediate B; S3: Add intermediate B into absolute ethanol, then add potassium hydroxide and stir. After heating and reacting, acidify, filter by suction, dry, and recrystallize to obtain intermediate C; S4: Add glycerol polyoxyethylene ether into a container, then add intermediate C and p-toluenesulfonic acid, and stir and react in an oil bath. After the reaction ends, cool and dry under vacuum to obtain the co-surfactant.

7. The anti-salt foam drainage aid for oilfield exploitation according to claim 6, wherein, In the above S1, the dosage ratio of p-methoxyaniline, 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 the above S2, the dosage 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.

8. An anti-salt foam drainage aid for oilfield exploitation according to claim 6, characterized in that, In the above S3, the dosage ratio of intermediate B, absolute ethanol and potassium hydroxide is (5 - 7.5) g : (200 - 300) mL : (6.01 - 7.84) g; in the above S4, the dosage ratio of glycerol polyoxyethylene ether, intermediate C and p-toluenesulfonic acid is (8 - 12) g : (7 - 10.4) g : (0.03 - 0.046) g.

9. The preparation method of an anti-salt foam drainage aid for oilfield exploitation according to any one of claims 1-8, characterized in that, It includes the following steps: Step 1: Add the main surfactant into the reaction kettle, raise the temperature, and then slowly add cocamidopropyl betaine, and continue to stir to obtain the main mixture; Step 2: Add the co-surfactant into the main mixture, then slowly add disodium EDTA, nano-silica and isopropanol, stir and mix, then stand, filter, and homogenize to obtain the salt-resistant foam drainage agent for oilfield exploitation.

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