An oil and gas field plugging agent and a preparation method thereof

Abstract

The application relates to an oil and gas field plugging remover and a preparation method thereof, and belongs to the technical field of oil and gas development. The plugging remover comprises the following components in percentage by mass: 15-25% of a multi-dentate chelating acid compound, 5-8% of a fluorinated salt, 2-5% of a surfactant compound, 1-3% of an inhibitor, 2-4% of a mutual solvent, 0.5-1% of a dispersant, and the balance of water; the multi-dentate chelating acid compound comprises aminotri (methylene) phosphonic acid and hydroxyethylidene diphosphonic acid; and the surfactant compound comprises a quaternary ammonium salt surfactant and a PO-EO block copolymer. The plugging remover provided by the application can achieve good plugging removal effect on inorganic-organic composite plugging, has low corrosion rate on a pipe string, reduces unnecessary damage to the pipe string, and has wide market prospects. The application further provides a preparation method of the plugging remover, the process of which is simple, has low requirements on the environment and equipment, and is suitable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas development technology, specifically relating to an oil and gas field unblocking agent and its preparation method. Background Technology

[0002] As oil and gas field development enters its middle and late stages, blockage problems in oil and gas wells and formations become increasingly prominent, severely impacting oil and gas field production. Injecting unblocking agents into the blocked areas is an effective means of relieving blockages in oil and gas wells and formations.

[0003] Due to varying environmental and operating conditions, blockages are complex in composition, often containing both organic and inorganic compounds, such as carbonate scale, silicate scale, sulfate scale, sludge, corrosion products, and microbial scale. Current unblocking agents primarily consist of various acids, organic solvents, and surfactants, presenting the following technical bottlenecks:

[0004] First, the chelating efficiency of chelating acid-based unblocking agents is limited. Single chelating agents have insufficient chelating ability for complex scale blockages (such as calcium-barium complex scale), and the scale dissolution rate is generally lower than 85%.

[0005] Secondly, the reaction of self-generated acid-based unblocking agents composed of hydrofluoric acid, arginine, or ammonium bifluoride and hydrochloric acid is out of control. The unblocking agent reacts rapidly with the blockage, resulting in poor unblocking effect on blockages in the formation, especially deep in the formation. More than 90% of the dissolution occurs in the near-wellbore area.

[0006] Third, surfactant-based unblocking agents have poor permeability and cannot penetrate deep into dense blockages, resulting in poor dissolving and stripping effects;

[0007] Fourth, some of the blockages are prone to secondary aggregation after being unblocked, and the insoluble substances are difficult to disperse, causing the insoluble substances to gather together and form new dense blockages.

[0008] Extensive research has been conducted by those skilled in the art on the problem of oil and gas well and formation blockage. Existing unblocking agents often have limited applicability; they may be effective in resolving certain types of blockages, but their effectiveness in unblocking complex, compound blockages is generally poor or even negligible. Summary of the Invention

[0009] Therefore, the purpose of this application is to provide a deblocking agent and its preparation method, which constructs a synergistic system of "chelation-dissolution-penetration-dispersion-mutual solubility", which can achieve good deblocking effect on inorganic-organic composite blockages, and has a low corrosion rate on the tubing, reducing unnecessary damage to the tubing.

[0010] The embodiments of this application are implemented as follows:

[0011] This application provides an oil and gas field unblocking agent, comprising the following components by mass percentage: 15%–25% multidentate chelate acid compound, 5%–8% fluoride salt, 2%–5% surfactant compound, 1%–3% corrosion inhibitor, 2%–4% miscible solvent, 0.5%–1% dispersant, and the balance being water.

[0012] The surfactant complex comprises a quaternary ammonium salt surfactant and a PO-EO block copolymer, wherein the quaternary ammonium salt surfactant comprises molecules with the structure shown in formula (1):

[0013] , structure (1).

[0014] Furthermore, the multidentate chelating acid complex includes aminotrimethylenephosphonic acid and hydroxyethylidene diphosphonic acid, wherein the mass ratio of aminotrimethylenephosphonic acid to hydroxyethylidene diphosphonic acid is (2.5-3.5):(1.5-2.5).

[0015] Furthermore, the fluoride salt includes ammonium bifluoride and potassium fluorosilicate, wherein the mass ratio of ammonium bifluoride to potassium fluorosilicate is (4.5-5.5):(0.5-1.5).

[0016] Furthermore, the corrosion inhibitor includes an imidazoline derivative and benzotriazole, wherein the mass ratio of the imidazoline derivative to the benzotriazole is (3.5-4.5):(0.5-1.5).

[0017] Furthermore, the mutual solvents include at least one of ethylene glycol butyl ether and diethylene glycol methyl ether.

[0018] Furthermore, the dispersant includes modified sodium polyacrylate, which is prepared by taking 7-9 parts of acrylic acid, 1.5-2.5 parts of 2-acrylamide-2-methylpropanesulfonic acid, and 15-25 parts of water by mass ratio, mixing them, and then adding 0.7%-0.9% of persulfate based on the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid, heating to 60-70°C, and reacting for 3-5 hours.

[0019] Furthermore, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is (2.5-3.5):(1.5-2.5).

[0020] Furthermore, the preparation method of the quaternary ammonium salt surfactant includes the following steps:

[0021] S1. By weight, take 90-110 parts of 1,1,3,3-tetramethyldisiloxane and 40-80 parts of anhydrous ethanol and place them in a reaction vessel. Stir and then continuously introduce nitrogen gas.

[0022] S2, Catalysis was carried out by adding platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane;

[0023] S3. Heat to 70-80℃ and stir continuously. Add 105-115 parts of allyl chloride dropwise and react for 4-8 hours.

[0024] S4. Cool and filter to remove precipitate. Distill the filtrate under vacuum and collect the fraction at 60-70℃.

[0025] S5. Dissolve the collected fraction in 235-315 parts of isopropanol, cool to 0-5℃ and stir, then add 150-170 parts of a 30%-35% trimethylamine aqueous solution dropwise.

[0026] S6. Heat to 60-70℃ and reflux with stirring for 4-6 hours;

[0027] S7. Cool to 20-30℃ and distill under vacuum to obtain a slurry.

[0028] S8. Mix the slurry with 180-270 parts of an extractant, wherein the extractant includes at least one of ethyl acetate and diethyl ether. After shaking, washing, extracting, and allowing to stand for separation, remove the organic phase layer and retain the solid and aqueous phase layers.

[0029] S9. Filter and wash the solid and aqueous phase layers, and vacuum dry the filter cake at 40-50°C for 6-12 hours.

[0030] Furthermore, the molecular weight of the PO-EO block copolymer is 2000 to 3000.

[0031] The oil and gas field unblocking agent provided in this application has a unique formula, components and dosage created by the applicant. It has good compatibility and synergistic effects, and achieves efficient dissolution and dispersion of blockages such as carbonate scale, sulfate scale, silicate minerals, corrosion products, and sludge. It has broad market prospects.

[0032] The principle lies in the fact that the multidentate chelating acid complex forms a broad-spectrum chelating network, capable of covering a variety of metal ions and exhibiting strong chelating ability. Aminotrimethylene phosphonic acid (ATPA) contains three phosphonic acid groups and one amino group, which can form stable six-membered ring chelates with Ca²⁺, Mg²⁺, and other ions through multidentate coordination. Hydroxyethylidene diphosphonic acid (HEDDI) contains two phosphonic acid groups and one hydroxyl group, which can form soluble complexes with Fe³⁺, Cu²⁺, and other ions, exhibiting particularly strong dissolving ability for corrosion products. When APA and HEDDI are compounded at a mass ratio of (2.5–3.5):(1.5–2.5), the calcium chelating ability of APA and the iron chelating ability of HEDDI complement each other, significantly improving the dissolution efficiency of mixed scale and solving the problem of insufficient effectiveness of single chelating acids against complex blockages.

[0033] Multidentate chelate acid complexes, as organophosphonic acids, exhibit excellent thermal stability. When used in conjunction with fluoride salts, they effectively suppress rapid and vigorous reaction processes, preventing runaway reactions at high temperatures. Fluoride salts possess excellent slow-release properties; ammonium bifluoride, acting as a "slow-release fluoride source," gradually dissociates hydrogen and fluoride ions in aqueous solution, reacting with silicates to form soluble fluorosilicic acid. Potassium fluorosilicate, acting as a "fluoride ion buffer," regulates the fluoride ion concentration in the system through its dissolution equilibrium, preventing excessive local hydrofluoric acid concentrations that could lead to excessive dissolution of formation rocks. In short, ammonium bifluoride provides the primary fluoride ion source, while potassium fluorosilicate slows the reaction rate through the common ion effect, transforming the dissolution process of silicate minerals from an "explosive" to a "uniform permeation" process, thus expanding the unblocking radius.

[0034] Quaternary ammonium salt surfactants contain siloxane segments with an "amphiphilic, double-tailed" structure. The siloxane segments provide extremely low surface tension, while the quaternary ammonium salt groups provide cationic charges, allowing for directional adsorption onto negatively charged rock surfaces and reversing water wettability to oil wettability. The PO segment (polyoxypropylene) of the PO-EO block copolymer is hydrophobic and oleophilic, while the EO segment (polyoxyethylene) is hydrophilic; the terminal methyl end-capping enhances its salt resistance. The combined use of quaternary ammonium salt surfactants and PO-EO block copolymers effectively reduces interfacial tension and enables directional penetration, avoiding the penetration difficulties found in existing technologies. This further improves the penetration capacity of the unblocking agent. Furthermore, the applicant's original research discovered that when the PO:EO mass ratio of the PO-EO block copolymer is 1:(1.5–2.5), it can form "worm-like micelles," further reducing the viscosity of the sludge emulsion and significantly improving the flow capacity of the unblocking agent in dense blockages.

[0035] The sulfonic acid groups in the sulfonic acid-modified sodium polyacrylate molecular chain provide a strong negative charge, which disperses insoluble particles (such as SiO2) at the nanoscale through electrostatic repulsion. The high absolute value of the zeta potential effectively prevents secondary aggregation of insoluble particles. In other words, the sulfonic acid-modified sodium polyacrylate maintains dispersion stability through electrostatic repulsion, effectively avoiding secondary clogging after the blockage is cleared.

[0036] In addition, the unblocking agent incorporates a compound of imidazoline derivatives and benzotriazole as a corrosion inhibitor. The imidazoline ring forms a protective film through physical adsorption, while benzotriazole chelates and passivates catalytic ions such as Cu²⁺ and Fe²⁺. The compound significantly reduces the corrosion rate of tubing and pipelines.

[0037] This application also provides a method for preparing the above-mentioned oil and gas field unblocking agent, including the following steps:

[0038] S1. Add water, which accounts for 25% to 35% of the total mass of the oil and gas field unblocking agent, to the reaction vessel by mass percentage. Heat to 55 to 65°C and stir. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 25 to 35 minutes.

[0039] S2. Add the measured amount of PO-EO block copolymer and continue stirring for 30 to 40 minutes;

[0040] S3. Add the measured amount of quaternary ammonium salt surfactant and continue stirring for 25-35 minutes;

[0041] S4. Keep the rotation speed constant, cool down to 20-30℃, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant, and continue stirring for 30-40 minutes.

[0042] The preparation method provided in this application is simple, has low requirements for environment and equipment, is suitable for industrial application, and has high market value.

[0043] Compared with existing technologies, the unblocking agent provided in this application has the following beneficial effects:

[0044] As a deblocking agent, it has a wide range of applications, effectively dissolving various blockages such as carbonate scale, silicate minerals, corrosion products, and sludge. Its deblocking efficiency is significantly improved, with a dissolution and dispersion rate exceeding 95%. Furthermore, it exhibits a low corrosion rate on steel materials; at 120℃, the corrosion rate on N80 carbon steel is ≤20 g / (㎡·h), effectively reducing damage to the tubing. Compared to 10% hydrochloric acid and terpineic acid, terpineic acid, specifically a mixture of 12% hydrochloric acid and 3% hydrofluoric acid, possesses excellent slowing properties. Moreover, the dissolved blockages are less prone to aggregation after deblocking, preventing secondary blockages. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. The illustrative embodiments and descriptions of this application are for explanation only and are not intended to limit the scope of this application. Any product identical or similar to this application, derived by any person based on the teachings of this application or by combining features of this application with other prior art, falls within the protection scope of this application.

[0046] For any experimental steps or conditions not specified in the examples, the procedures or conditions described in the conventional experimental procedures in the art can be followed. Reagents and other instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0047] This application provides a deblocking agent comprising the following components by mass percentage:

[0048] The compound contains 15%–25% of a multidentate chelating acid complex, which includes aminotrimethylenephosphonic acid and hydroxyethylidene diphosphonic acid. Preferably, the mass ratio of aminotrimethylenephosphonic acid to hydroxyethylidene diphosphonic acid is (2.5–3.5):(1.5–2.5).

[0049] The fluoride salts comprise 5% to 8%, including ammonium bifluoride and potassium fluorosilicate. Preferably, the mass ratio of ammonium bifluoride to potassium fluorosilicate is (4.5 to 5.5):(0.5 to 1.5).

[0050] 2%–5% surfactant complex, comprising quaternary ammonium salt surfactants and PO-EO block copolymers. Quaternary ammonium salt surfactants include molecules with the structure shown in formula (1):

[0051] Structural formula (1);

[0052] The preparation method of this quaternary ammonium salt surfactant includes the following steps:

[0053] S1. By weight, take 90-110 parts of 1,1,3,3-tetramethyldisiloxane and 40-80 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0054] S2. Add a platinum complex catalyst to the reaction system. The catalyst is platinum(0)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane.

[0055] S3. Under continuous nitrogen protection, stir and heat to 70-80°C, slowly add 105-115 parts of allyl chloride to the reaction system. After the addition is complete, continue to maintain the temperature at 70-80°C and stir. React for 4-8 hours.

[0056] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 60-70℃ to obtain a colorless and transparent intermediate liquid.

[0057] S5. Dissolve the intermediate liquid obtained in step S4 in 235-315 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 150-170 parts of trimethylamine aqueous solution with a mass fraction of 30%-35% dropwise under stirring.

[0058] S6. Heat the reaction system to 60-70°C, stir and reflux for 4-6 hours;

[0059] S7. Cool the reaction liquid system to 20-30°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0060] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 180-270 parts of ethyl acetate and / or diethyl ether, shake and wash thoroughly, extract, let stand to separate the layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0061] S9. Filter the solid / aqueous phase obtained in step S8, wash the solid 2-3 times with ethyl acetate and / or diethyl ether, place the filter cake in a vacuum drying oven, and vacuum dry at 40-50°C for 6-12 hours to obtain a white to off-white quaternary ammonium salt surfactant containing siloxane segments.

[0062] The PO-EO block copolymer is a commercially available product, and the applicant prefers a molecular weight range of 2000 to 3000. The preferred molecular weight range ensures that the emulsification ability is not insufficient due to the molecular weight being too small, nor that the emulsification effect is affected by the excessive entanglement of the lipophilic segments due to the molecular weight being too large. This achieves the effect of the EO segment being hydrophilic while the length of the lipophilic chain of the PO segment is matched to the molecular size of various oil contaminants, resulting in an emulsion system with excellent stability.

[0063] Preferably, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is (2.5-3.5):(1.5-2.5).

[0064] The corrosion inhibitor comprises 1% to 3% of an imidazoline derivative and benzotriazole. Preferably, the mass ratio of the imidazoline derivative to benzotriazole is (3.5 to 4.5):(0.5 to 1.5).

[0065] 2% to 4% of mutual solvents, including at least one of ethylene glycol butyl ether and diethylene glycol methyl ether.

[0066] A dispersant of 0.5%–1%, including modified sodium polyacrylate, is used. The preparation method is as follows: 7–9 parts by mass of acrylic acid, 1.5–2.5 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 15–25 parts by mass of water are mixed and polymerized under the action of an initiator to obtain modified sodium polyacrylate with sulfonic acid groups introduced into the molecular chain segments. The initiator is preferably persulfate, and the amount of initiator is preferably 0.7%–0.9% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is preferably 60–70°C, and the reaction time is preferably 3–5 hours.

[0067] The remainder is water.

[0068] The unblocking agent provided in this application has a unique formula, components, and dosage. It has good compatibility and synergistic effects, achieving efficient dissolution and dispersion of blockages such as carbonate scale, sulfate scale, silicate minerals, corrosion products, and sludge. It has broad market prospects.

[0069] This application also provides a method for preparing a plugging agent, including the following steps:

[0070] S1. Add water, accounting for 25%–35% of the total mass of the unblocking agent, to the reaction vessel by mass percentage. Heat to 55–65°C and stir, preferably at a stirring speed of 100–200 rpm. Then add the measured amounts of aminotrimethylenephosphonic acid and hydroxyethylidene diphosphonic acid, and continue stirring for 25–35 minutes.

[0071] S2. Keeping the temperature and speed constant, add the metered PO-EO block copolymer and continue stirring for 30 to 40 minutes;

[0072] S3. Keep the temperature and speed constant, add the measured amount of quaternary ammonium salt surfactant, and continue stirring for 25 to 35 minutes;

[0073] S4. Keep the rotation speed constant, cool down to 20-30℃, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence, and continue stirring for 30-40 minutes to obtain unblocking agent.

[0074] This method is simple in process, has low requirements for environment and equipment, is suitable for industrial application, and has high market value.

[0075] Example 1:

[0076] The unblocking agent provided in Example 1 comprises the following components by mass percentage: 15% multidentate chelate acid complex, 5% fluoride salt, 2% surfactant complex, 1% corrosion inhibitor, 2% miscible solvent, 0.5% dispersant, and the balance being water.

[0077] In the multidentate chelate acid complex, the mass ratio of aminotrimethylene phosphonic acid to hydroxyethylidene diphosphonic acid is 2.5:1.5.

[0078] In the fluoride salt, the mass ratio of ammonium bifluoride to potassium fluorosilicate is 4.5:0.5.

[0079] In the surfactant compound, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is 2.5:1.5; the preparation method of this quaternary ammonium salt surfactant is as follows:

[0080] S1. By weight, take 90 parts of 1,1,3,3-tetramethyldisiloxane and 40 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0081] S2. Add platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane catalyst to the reaction system;

[0082] S3. Continuously purge with nitrogen for protection, stir and heat to 70°C, slowly add 105 parts of allyl chloride to the reaction system, and continue to maintain the temperature at 70°C and stir after the addition is complete, and react for 4 hours.

[0083] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 60-70℃ to obtain a colorless and transparent intermediate liquid.

[0084] S5. Dissolve the intermediate liquid obtained in step S4 in 235 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 150 parts of trimethylamine aqueous solution with a mass fraction of 30% dropwise under stirring.

[0085] S6. Heat the reaction system to 60°C, stir and reflux for 4 hours;

[0086] S7. Cool the reaction liquid system to 20°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0087] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 180 parts of a mixture of ethyl acetate and diethyl ether, shake and wash thoroughly, extract, let stand to separate the layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0088] S9. Filter the solid / aqueous phase layer obtained in step S8, wash the solid twice with a mixture of ethyl acetate and diethyl ether, place the filter cake in a vacuum drying oven, and vacuum dry at 40°C for 6 hours to obtain a quaternary ammonium salt surfactant.

[0089] In the corrosion inhibitor, the mass ratio of imidazoline derivative to benzotriazole is 3.5:0.5.

[0090] The mutual solvent is ethylene glycol butyl ether.

[0091] The dispersant is specifically modified sodium polyacrylate, which is prepared as follows: 7 parts by mass of acrylic acid, 1.5 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 15 parts by mass of water are mixed and then subjected to polymerization under the action of an initiator, ammonium persulfate, at a dosage of 0.7% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is 60℃, and the reaction time is 3 hours.

[0092] This unblocking agent is prepared by the following method:

[0093] S1. Add water, which accounts for 25% of the total mass of the unblocking agent, to the reaction vessel by mass percentage. Heat to 55°C and stir at 100 rpm. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 25 minutes.

[0094] S2. Keep the temperature and speed constant, add the metered PO-EO block copolymer, and continue stirring for 30 minutes;

[0095] S3. Keep the temperature and speed constant, add the measured amount of surfactant, and continue stirring for 25 minutes;

[0096] S4. Keep the rotation speed constant, cool down to 20°C, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence, and continue stirring for 30 minutes to obtain unblocking agent.

[0097] Example 2:

[0098] The unblocking agent provided in Example 2 comprises the following components by mass percentage: 25% multidentate chelate acid complex, 8% fluoride salt, 5% surfactant complex, 3% corrosion inhibitor, 4% miscible solvent, 1% dispersant, and the balance being water.

[0099] In the multidentate chelate acid complex, the mass ratio of aminotrimethylene phosphonic acid to hydroxyethylidene diphosphonic acid is 3.5:2.5.

[0100] In the fluoride salt, the mass ratio of ammonium bifluoride to potassium fluorosilicate is 5.5:1.5.

[0101] In the surfactant compound, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is 3.5:2.5; the preparation method of this quaternary ammonium salt surfactant is as follows:

[0102] S1. By weight, take 110 parts of 1,1,3,3-tetramethyldisiloxane and 80 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0103] S2. Add platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane catalyst to the reaction system;

[0104] S3. Continuously purge with nitrogen for protection, stir and heat to 80°C, slowly add 115 parts of allyl chloride to the reaction system, and continue to maintain the temperature at 80°C and stir after the addition is complete, and react for 8 hours.

[0105] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 60-70℃ to obtain a colorless and transparent intermediate liquid.

[0106] S5. Dissolve the intermediate liquid obtained in step S4 in 315 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 170 parts of trimethylamine aqueous solution with a mass fraction of 35% dropwise under stirring.

[0107] S6. Heat the reaction system to 70°C, stir and reflux for 6 hours;

[0108] S7. Cool the reaction liquid system to 30°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0109] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 270 parts of ethyl acetate, shake and wash thoroughly, extract, let stand and separate the layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0110] S9. Filter the solid / aqueous phase layer obtained in step S8, wash the solid three times with ethyl acetate, place the filter cake in a vacuum drying oven, and vacuum dry at 50°C for 12 hours to obtain a quaternary ammonium salt surfactant.

[0111] In the corrosion inhibitor, the mass ratio of imidazoline derivative to benzotriazole is 4.5:1.5.

[0112] The specific mutual solvent is diethylene glycol methyl ether.

[0113] The dispersant is specifically modified sodium polyacrylate, which is prepared as follows: 9 parts by mass of acrylic acid, 2.5 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 25 parts by mass of water are mixed and then subjected to polymerization under the action of an initiator. The initiator is potassium persulfate, and the amount of initiator is 0.9% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is 70℃, and the reaction time is 5 hours.

[0114] This unblocking agent is prepared by the following method:

[0115] S1. Add water, which accounts for 35% of the total mass of the unblocking agent, to the reaction vessel by mass percentage. Heat to 65°C and stir at 200 rpm. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 35 minutes.

[0116] S2. Keep the temperature and speed constant, add the metered PO-EO block copolymer, and continue stirring for 40 minutes;

[0117] S3. Keep the temperature and speed constant, add the measured amount of surfactant, and continue stirring for 35 minutes;

[0118] S4. Keep the rotation speed constant, cool down to 30°C, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence, and continue stirring for 40 minutes to obtain unblocking agent.

[0119] Example 3:

[0120] The unblocking agent provided in Example 3 comprises the following components by mass percentage: 20% multidentate chelate acid complex, 6.5% fluoride salt, 3.5% surfactant complex, 2% corrosion inhibitor, 3% miscible solvent, 0.75% dispersant, and the balance being water.

[0121] In the multidentate chelate acid complex, the mass ratio of aminotrimethylene phosphonic acid to hydroxyethylidene diphosphonic acid is 3:2.

[0122] In fluoride salts, the mass ratio of ammonium bifluoride to potassium fluorosilicate is 5:1.

[0123] In the surfactant compound, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is 3:2; the preparation method of this quaternary ammonium salt surfactant is as follows:

[0124] S1. By weight, take 100 parts of 1,1,3,3-tetramethyldisiloxane and 60 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0125] S2. Add platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane catalyst to the reaction system;

[0126] S3. Continuously purge with nitrogen for protection, stir and heat to 75°C, slowly add 110 parts of allyl chloride to the reaction system, and continue to maintain the temperature at 75°C and stir after the addition is complete, and react for 6 hours.

[0127] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 60-70℃ to obtain a colorless and transparent intermediate liquid.

[0128] S5. Dissolve the intermediate liquid obtained in step S4 in 270 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 160 parts of trimethylamine aqueous solution with a mass fraction of 35% dropwise under stirring.

[0129] S6. Heat the reaction system to 65°C, stir and reflux for 5 hours;

[0130] S7. Cool the reaction liquid system to 25°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0131] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 225 parts of diethyl ether, shake and wash thoroughly, extract, let stand to separate the layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0132] S9. Filter the solid / aqueous phase layer obtained in step S8, wash the solid three times with diethyl ether, place the filter cake in a vacuum drying oven, and vacuum dry at 45°C for 9 hours to obtain a quaternary ammonium salt surfactant.

[0133] In the corrosion inhibitor, the mass ratio of imidazoline derivative to benzotriazole is 4:1.

[0134] The miscible solvents are ethylene glycol butyl ether and diethylene glycol methyl ether in a mass ratio of 1:1.

[0135] The dispersant is specifically modified sodium polyacrylate, which is prepared as follows: 8 parts by mass of acrylic acid, 2 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 20 parts by mass of water are mixed and then subjected to polymerization under the action of an initiator. The initiator is ammonium persulfate, and the amount of initiator is 0.8% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is 50℃, and the reaction time is 4 hours.

[0136] This unblocking agent is prepared by the following method:

[0137] S1. Add water, which accounts for 30% of the total mass of the unblocking agent, to the reaction vessel by mass percentage. Heat to 60°C and stir at 150 rpm. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 30 minutes.

[0138] S2. Keeping the temperature and speed constant, add the metered PO-EO block copolymer and continue stirring for 35 minutes.

[0139] S3. Keep the temperature and speed constant, add the measured amount of surfactant, and continue stirring for 30 minutes;

[0140] S4. Keep the rotation speed constant, cool down to 25°C, and then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence. Continue stirring for 35 minutes to obtain the unblocking agent.

[0141] Example 4:

[0142] The unblocking agent provided in Example 4 comprises the following components by mass percentage: 18% multidentate chelate acid complex, 7% fluoride salt, 3% surfactant complex, 2.5% corrosion inhibitor, 2.5% miscible solvent, 0.9% dispersant, and the balance being water.

[0143] In the multidentate chelate acid complex, the mass ratio of aminotrimethylene phosphonic acid to hydroxyethylidene diphosphonic acid is 2.8:2.3.

[0144] In the fluoride salt, the mass ratio of ammonium bifluoride to potassium fluorosilicate is 4.8:1.4.

[0145] In the surfactant compound, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is 3.2:2.4; the preparation method of this quaternary ammonium salt surfactant is as follows:

[0146] S1. By weight, take 105 parts of 1,1,3,3-tetramethyldisiloxane and 50 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0147] S2. Add platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane catalyst to the reaction system;

[0148] S3. Continuously purge with nitrogen for protection, stir and heat to 70°C, slowly add 115 parts of allyl chloride to the reaction system, and continue to maintain the temperature at 80°C and stir after the addition is complete, and react for 5 hours.

[0149] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 60-70℃ to obtain a colorless and transparent intermediate liquid.

[0150] S5. Dissolve the intermediate liquid obtained in step S4 in 300 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 170 parts of trimethylamine aqueous solution with a mass fraction of 32% dropwise under stirring.

[0151] S6. Heat the reaction system to 70°C, stir and reflux for 4 hours;

[0152] S7. Cool the reaction liquid system to 30°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0153] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 200 parts of a mixture of ethyl acetate and diethyl ether, shake and wash thoroughly, extract, let stand to separate the layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0154] S9. Filter the solid / aqueous phase layer obtained in step S8, wash the solid twice with a mixture of ethyl acetate and diethyl ether, place the filter cake in a vacuum drying oven, and vacuum dry at 50°C for 10 hours to obtain a quaternary ammonium salt surfactant.

[0155] In the corrosion inhibitor, the mass ratio of imidazoline derivative to benzotriazole is 3.7:1.4.

[0156] The mutual solvents are ethylene glycol butyl ether and diethylene glycol methyl ether in a mass ratio of 1:2.

[0157] The dispersant is specifically modified sodium polyacrylate, which is prepared as follows: 7.5 parts by mass of acrylic acid, 1.9 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 18 parts by mass of water are mixed and then subjected to polymerization under the action of an initiator, ammonium persulfate, at a dosage of 0.75% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is 48℃, and the reaction time is 3.5 hours.

[0158] This unblocking agent is prepared by the following method:

[0159] S1. Add water, which accounts for 28% of the total mass of the unblocking agent, to the reactor by mass percentage. Heat to 58°C and stir at 120 rpm. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 28 minutes.

[0160] S2. Keeping the temperature and speed constant, add the metered PO-EO block copolymer and continue stirring for 33 minutes.

[0161] S3. Keep the temperature and speed constant, add the measured amount of surfactant, and continue stirring for 28 minutes;

[0162] S4. Keep the rotation speed constant, cool down to 22°C, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence, and continue stirring for 33 minutes to obtain unblocking agent.

[0163] Example 5:

[0164] The unblocking agent provided in Example 5 comprises the following components by mass percentage: 22% multidentate chelate acid complex, 6% fluoride salt, 4% surfactant complex, 1.5% corrosion inhibitor, 3.5% miscible solvent, 0.6% dispersant, and the balance being water.

[0165] In the multidentate chelate acid complex, the mass ratio of aminotrimethylene phosphonic acid to hydroxyethylidene diphosphonic acid is 3.3:1.9.

[0166] In the fluoride salt, the mass ratio of ammonium bifluoride to potassium fluorosilicate is 4.7:1.4.

[0167] In the surfactant compound, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is 3.3:1.6; the preparation method of this quaternary ammonium salt surfactant is as follows:

[0168] S1. By weight, take 100 parts of 1,1,3,3-tetramethyldisiloxane and 60 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0169] S2. Add platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane catalyst to the reaction system;

[0170] S3. Continuously purge with nitrogen for protection, stir and heat to 75°C, slowly add 110 parts of allyl chloride to the reaction system, and continue to maintain the temperature at 75°C and stir after the addition is complete, and react for 6 hours.

[0171] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 65°C to obtain a colorless and transparent intermediate liquid.

[0172] S5. Dissolve the intermediate liquid obtained in step S4 in 275 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 160 parts of trimethylamine aqueous solution with a mass fraction of 30% dropwise under stirring.

[0173] S6. Heat the reaction system to 65°C, stir and reflux for 5 hours;

[0174] S7. Cool the reaction liquid system to 25°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0175] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 225 parts of diethyl ether, shake and wash thoroughly, extract, let stand to separate the layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0176] S9. Filter the solid / aqueous phase layer obtained in step S8, wash the solid twice with diethyl ether, place the filter cake in a vacuum drying oven, and vacuum dry at 45°C for 9 hours to obtain a quaternary ammonium salt surfactant.

[0177] In the corrosion inhibitor, the mass ratio of imidazoline derivative to benzotriazole is 4.0:0.9.

[0178] The mutual solvent is ethylene glycol butyl ether.

[0179] The dispersant is specifically modified sodium polyacrylate, which is prepared as follows: 8.5 parts by mass of acrylic acid, 1.6 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 22 parts by mass of water are mixed and then subjected to polymerization under the action of an initiator, potassium persulfate, at a dosage of 0.85% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is 52℃, and the reaction time is 4.5 hours.

[0180] This unblocking agent is prepared by the following method:

[0181] S1. Add water, which accounts for 33% of the total mass of the unblocking agent, to the reactor by mass percentage. Heat to 63°C and stir at 130 rpm. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 25 minutes.

[0182] S2. Keeping the temperature and speed constant, add the metered PO-EO block copolymer and continue stirring for 38 minutes;

[0183] S3. Keep the temperature and speed constant, add the measured amount of surfactant, and continue stirring for 30 minutes;

[0184] S4. Keep the rotation speed constant, cool down to 24°C, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence, and continue stirring for 38 minutes to obtain unblocking agent.

[0185] Example 6:

[0186] The unblocking agent provided in Example 6 comprises the following components by mass percentage: 19% multidentate chelate acid complex, 6.5% fluoride salt, 4.5% surfactant complex, 2.2% corrosion inhibitor, 3.3% miscible solvent, 0.6% dispersant, and the balance being water.

[0187] In the multidentate chelate acid complex, the mass ratio of aminotrimethylene phosphonic acid to hydroxyethylidene diphosphonic acid is 3.2:1.7.

[0188] In the fluoride salt, the mass ratio of ammonium bifluoride to potassium fluorosilicate is 5.2:0.9.

[0189] In the surfactant compound, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is 3.0:2.2; the preparation method of this quaternary ammonium salt surfactant is as follows:

[0190] S1. By weight, take 95 parts of 1,1,3,3-tetramethyldisiloxane and 55 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0191] S2. Add platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane catalyst to the reaction system;

[0192] S3. Continuously purge with nitrogen for protection, stir and heat to 70°C, slowly add 105 parts of allyl chloride to the reaction system, and continue to maintain the temperature at 70°C and stir after the addition is complete, and react for 5 hours.

[0193] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 60°C to obtain a colorless and transparent intermediate liquid.

[0194] S5. Dissolve the intermediate liquid obtained in step S4 in 255 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 155 parts of trimethylamine aqueous solution with a mass fraction of 35% dropwise under stirring.

[0195] S6. Heat the reaction system to 60°C, stir and reflux for 4 hours;

[0196] S7. Cool the reaction liquid system to 20°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0197] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 250 parts of a mixture of ethyl acetate and diethyl ether, shake and wash thoroughly, extract, allow to stand and separate into layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0198] S9. Filter the solid / aqueous phase layer obtained in step S8, wash the solid three times with a mixture of ethyl acetate and diethyl ether, place the filter cake in a vacuum drying oven, and vacuum dry at 40°C for 6 hours to obtain a quaternary ammonium salt surfactant.

[0199] In the corrosion inhibitor, the mass ratio of imidazoline derivative to benzotriazole is 4.2:1.3.

[0200] The specific mutual solvent is diethylene glycol methyl ether.

[0201] The dispersant is specifically modified sodium polyacrylate, which is prepared as follows: 7 parts by mass of acrylic acid, 2.2 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 21 parts by mass of water are mixed and then subjected to polymerization under the action of an initiator, ammonium persulfate, at a dosage of 0.83% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is 53℃, and the reaction time is 4 hours.

[0202] This unblocking agent is prepared by the following method:

[0203] S1. Add water, which accounts for 27% of the total mass of the unblocking agent, to the reaction vessel by mass percentage. Heat to 59°C and stir at 170 rpm. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 30 minutes.

[0204] S2. Keeping the temperature and speed constant, add the metered PO-EO block copolymer and continue stirring for 35 minutes.

[0205] S3. Keep the temperature constant, reduce the speed to 120 rpm, add the measured amount of surfactant, and continue stirring for 30 minutes.

[0206] S4. Increase the rotation speed to 170 rpm, cool down to 25°C, and then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence. Continue stirring for 30 minutes to obtain the unblocking agent.

[0207] Example 7:

[0208] The unblocking agent provided in Example 7 comprises the following components by mass percentage: 15% multidentate chelate acid complex, 8% fluoride salt, 3.3% surfactant complex, 2.9% corrosion inhibitor, 2.1% miscible solvent, 0.67% dispersant, and the balance being water.

[0209] In the multidentate chelate acid complex, the mass ratio of aminotrimethylene phosphonic acid to hydroxyethylidene diphosphonic acid is 3.1:2.2.

[0210] In the fluoride salt, the mass ratio of ammonium bifluoride to potassium fluorosilicate is 5.0:1.3.

[0211] In the surfactant compound, the mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is 2.2:1.9; the preparation method of this quaternary ammonium salt surfactant is as follows:

[0212] S1. By weight, take 100 parts of 1,1,3,3-tetramethyldisiloxane and 70 parts of anhydrous ethanol and place them into a reaction vessel. Stir to mix them evenly, and then continuously introduce nitrogen into the reaction system to replace the air and maintain nitrogen protection.

[0213] S2. Add platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane catalyst to the reaction system;

[0214] S3. Continuously purge with nitrogen for protection, stir and heat to 78°C, slowly add 112 parts of allyl chloride to the reaction system, and continue to maintain the temperature at 77°C and stir after the addition is complete, and react for 7 hours.

[0215] S4. Cool the reaction system to room temperature, filter to remove the precipitate, transfer the filtrate to a rotary evaporator, distill under vacuum and collect the fraction at 70°C to obtain a colorless and transparent intermediate liquid.

[0216] S5. Dissolve the intermediate liquid obtained in step S4 in 235 parts of isopropanol, cool the system and maintain it at 0-5°C, and add 165 parts of trimethylamine aqueous solution with a mass fraction of 35% dropwise under stirring.

[0217] S6. Heat the reaction system to 68°C, stir and reflux for 5.5 hours;

[0218] S7. Cool the reaction liquid system to 28°C and transfer it to a rotary evaporator for vacuum distillation to obtain a viscous white or pale yellow paste.

[0219] S8. Transfer the slurry obtained in step S7 to a separatory funnel, add 250 parts of ethyl acetate, shake and wash thoroughly, extract, let stand to separate the layers, remove the upper organic phase, and retain the bottom solid / aqueous phase layer.

[0220] S9. Filter the solid / aqueous phase layer obtained in step S8, wash the solid three times with ethyl acetate, place the filter cake in a vacuum drying oven, and vacuum dry at 48°C for 10 hours to obtain a quaternary ammonium salt surfactant.

[0221] In the corrosion inhibitor, the mass ratio of imidazoline derivative to benzotriazole is 3.9:0.9.

[0222] The mutual solvents are ethylene glycol butyl ether and diethylene glycol methyl ether in a mass ratio of 1:0.6.

[0223] The dispersant is specifically modified sodium polyacrylate, which is prepared as follows: 7.7 parts by mass of acrylic acid, 2.3 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid, and 18 parts by mass of water are mixed and then subjected to polymerization under the action of an initiator, potassium persulfate, at a dosage of 0.88% of the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The reaction temperature is 41℃, and the reaction time is 3.4 hours.

[0224] This unblocking agent is prepared by the following method:

[0225] S1. Add water, which accounts for 35% of the total mass of the unblocking agent, to the reactor by mass percentage. Heat to 56°C and stir at 150 rpm. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 32 minutes.

[0226] S2. Keeping the temperature and speed constant, add the metered PO-EO block copolymer and continue stirring for 35 minutes.

[0227] S3. Keep the temperature and speed constant, add the measured amount of surfactant, and continue stirring for 33 minutes;

[0228] S4. Keep the rotation speed constant, cool down to 21°C, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant in sequence, and continue stirring for 40 minutes to obtain unblocking agent.

[0229] Comparative Example 1:

[0230] The unblocking agent was prepared according to the method, raw materials, and dosage of Example 1, except that 10% hydrochloric acid was used to replace the multidentate chelate acid complex, resulting in the product.

[0231] That is, the product in Comparative Example 1 includes the following components by mass percentage: 15% hydrochloric acid (10% by mass), 5% fluoride salt, 2% surfactant compound, 1% corrosion inhibitor, 2% miscible solvent, 0.5% dispersant, and the balance being water.

[0232] Comparative Example 2:

[0233] Except for the absence of fluoride salts, the unblocking agent was prepared according to the method, raw materials, and dosage of Example 2 to obtain the product.

[0234] That is, the product in Comparative Example 2 includes the following components by mass percentage: 25% multidentate chelate acid complex, 5% surfactant complex, 3% corrosion inhibitor, 4% miscible solvent, 1% dispersant, and the balance being water.

[0235] Comparative Example 3:

[0236] The unblocking agent was prepared according to the method, raw materials, and dosage of Example 3, except that JFC penetrant was used to replace the surfactant compound to obtain the product. JFC penetrant is a commercially available product, and its main components are fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether, which is a technologically mature nonionic surfactant widely used in industry.

[0237] That is, the product in Comparative Example 3 includes the following components by mass percentage: 20% multidentate chelate acid complex, 6.5% fluoride salt, 3.5% JFC penetrant, 2% corrosion inhibitor, 3% miscible solvent, 0.75% dispersant, and the balance being water.

[0238] Comparative Example 4:

[0239] The unblocking agent was prepared according to the method, raw materials, and dosage of Example 4, except that no corrosion inhibitor was used, and the product was obtained.

[0240] That is, the product in Comparative Example 4 includes the following components by mass percentage: 18% multidentate chelate acid complex, 7% fluoride salt, 3% surfactant complex, 2.5% miscible solvent, 0.9% dispersant, and the balance being water.

[0241] Comparative Example 5:

[0242] The unblocking agent was prepared according to the method, raw materials, and dosage of Example 5, except that a miscible solvent was not used, and the product was obtained.

[0243] That is, the product in Comparative Example 5 includes the following components by mass percentage: 22% multidentate chelate acid complex, 6% fluoride salt, 4% surfactant complex, 1.5% corrosion inhibitor, 0.6% dispersant, and the balance being water.

[0244] Comparative Example 6:

[0245] The unblocking agent was prepared according to the method, raw materials, and dosage of Example 6, except that sodium polyacrylate with an average molecular weight of 100,000 was used to replace the modified sodium polyacrylate dispersant in the original formula, and the product was obtained.

[0246] That is, the product in Comparative Example 6 includes the following components by mass percentage: 19% multidentate chelate acid complex, 6.5% fluoride salt, 4.5% surfactant complex, 2.2% corrosion inhibitor, 3.3% miscible solvent, 0.6% sodium polyacrylate, and the balance being water.

[0247] Comparative Example 7:

[0248] The unblocking agent was prepared according to the method, raw materials, and dosage of Example 7, except that citric acid was used to replace the multidentate chelate acid complex in the original formula to obtain the product.

[0249] That is, the product in Comparative Example 7 includes the following components by mass percentage: 15% citric acid, 8% fluoride salt, 3.3% surfactant complex, 2.9% corrosion inhibitor, 2.1% miscible solvent, 0.67% dispersant, and the balance being water.

[0250] The performance of the unblocking agents obtained in Examples 1-7 and Comparative Examples 1-7 will be tested below.

[0251] Test index 1, dissolution and dispersion ability:

[0252] Dissolution and dispersion ability is a core indicator for evaluating unblocking agents, reflecting their ability to dissolve and disperse blockages. Before testing, several identical, clean, and dry beakers and five different blockage samples were prepared. The unblocking agent provided in this application was used to conduct the dissolution and dispersion ability test.

[0253] The blockage samples were: marble (simulating carbonate scale), silica particles (simulating silicate minerals), ferrous sulfide (simulating corrosion products), oil-based mud (simulating sludge), and on-site blockage (which, after testing, included rock fragments, carbonate scale, iron corrosion products, sludge, etc.).

[0254] The specific testing method is as follows: First, weigh the dry, clean beakers separately and record the mass as m0; then place the blockage in the beaker and weigh it together with the beaker, and record the mass as m1; then the mass of the blockage is m1 - m0; then add 80 times the weight of the blockage remover to the beaker.

[0255] Unblocking ability tests were conducted at different temperatures. Specifically, when the test temperature was ≤95℃, the beaker mouth was sealed with a beaker sealing film, and then placed in an oven for dissolution and dispersion. When the test temperature was >95℃, all the blockage material and unblocking agent in the beaker were poured into a high-temperature aging tank lined with polytetrafluoroethylene, sealed, and then placed in an oven for dissolution and dispersion. All samples were dissolved for 4 hours, that is, the blockage material was dissolved and dispersed in the unblocking agent for 4 hours. Then, the mixture in the beaker or high-temperature aging tank was poured out and filtered through a 20-mesh sieve. The residue in the beaker or aging tank was also rinsed with water and filtered through a 20-mesh sieve to obtain all the residue. All the residue was transferred to another dry beaker (this beaker was pre-dried and weighed, and the mass was recorded as m2). Then, the beaker containing the residue was placed open in a drying oven at 25℃ and allowed to dry for 12 hours. The beaker and the residue were weighed together, and the mass was recorded as m3. The mass of the residue after drying is m3 - m2.

[0256] Dissolution and dispersion rate = [(m1-m0)-(m3-m2)] / (m1-m0)×100%. After experimental verification, the dissolution and dispersion rates of the unblocking agents obtained in Examples 1-7 and Comparative Examples 1-7 at different temperatures are shown in Table 1 and Table 2.

[0257] Table 1 shows the dissolution and dispersion rates (%) of the unblocking agents obtained in Examples 1-7 and Comparative Examples 1-7 at 70°C.

[0258]

[0259] As can be seen from Table 1, Examples 1 to 7 all have good dissolving and dispersing effects on various blockages. At 70°C, the dissolving and dispersing rates of the unblocking agents provided in Examples 1 to 7 for the five types of blockages are all >95%, which proves that the unblocking agents provided in this application have excellent dissolving and dispersing effects.

[0260] The unblocking agent provided in Comparative Example 1 had a worse dissolution and dispersion effect than that in Example 1, especially for ferrous sulfide (i.e., corrosion products) and on-site blockages, which demonstrated the superiority of the multidentate chelating acid compound in the unblocking agent formulation of this application.

[0261] Similarly, the unblocking agents provided in Comparative Examples 2-3 and 5-7 also showed weaker dissolution and dispersion effects than those in the comparative examples 2-3 and 5-7. These data demonstrate that the unblocking agent formulation provided in this application has better overall unblocking performance, a wider range of applications, and can meet the requirements of complex on-site working conditions.

[0262] In contrast, Comparative Example 4 lacked a corrosion inhibitor. This modification to the control did not affect the dissolution and dispersion effect. Therefore, in terms of data, Example 4 and Comparative Example 4 showed the same unblocking and dispersion effect.

[0263] In addition, the dispersant in Comparative Example 6 was replaced with sodium polyacrylate. After dissolving the blockage, the remaining blockage aggregated into clumps, which means there was a problem of "secondary blockage". This shows the superiority of sodium polyacrylate dispersant in the unblocking agent formulation of this application in avoiding secondary blockage.

[0264] Table 2 shows the dissolution and dispersion rates (%) of the unblocking agents obtained in Examples 1-7 and Comparative Examples 1-7 at 120℃.

[0265]

[0266] As can be seen from Table 2, at a temperature of 120℃, Examples 1 to 7 all have good dissolving and dispersing effects on various blockages, with a dissolving and dispersing rate ≥96.8%.

[0267] Based on the combined data from Examples 1-7 and Comparative Examples 1-7, and considering Tables 1 and 2, the dissolution and dispersion effect of the unblocking agent provided by this application is not negatively affected at 120°C compared to 70°C; in fact, the dissolution and dispersion effect is better after the temperature is increased.

[0268] Comparative Examples 1-3 and 5-7 also showed improved dissolution and dispersion rates for some blockages at 120℃, exhibiting consistent trends and patterns, confirming the stable dissolution and dispersion performance of the unblocking agent formulation provided in this application. However, the unblocking agents provided by Comparative Examples 1-3 and 5-7 still exhibit relatively low dissolution and dispersion rates for multi-component mixtures of blockages in the field, making them difficult to adapt to complex on-site conditions.

[0269] The anti-blocking agent formulation of Comparative Example 4 lacks a corrosion inhibitor, but the other components and preparation methods are the same as those of Example 4. The corrosion inhibitor has little effect on the dissolution and dispersion rate of the blockage. Therefore, Comparative Example 4 also has a good dissolution and dispersion effect on various blockages.

[0270] At 120°C, the unblocking agent formulation of Comparative Example 6 still exhibited the problem of secondary blockage caused by the residual blockage agglomerating into clumps after dissolving the blockage. However, other comparative examples and embodiments did not exhibit this problem, demonstrating the superiority of the unblocking agent formulation provided in this application in avoiding secondary blockage.

[0271] Test index 2, corrosion rate:

[0272] The static corrosion rate of N80 carbon steel under normal pressure at different temperatures was tested according to the method specified in SY / T5886-2018. The corrosion rate is expressed in g / (m²·h), and the test results are shown in Table 3.

[0273] Table 3 shows the corrosion rate data (g / (㎡·h)) of the unblocking agents obtained in Examples 1–7 at different temperatures.

[0274]

[0275] As shown in Table 3, when the temperature is ≤120℃, the unblocking agents provided in Examples 1-7 and Comparative Example 4 all exhibit the characteristic that the higher the temperature, the faster the corrosion of N80 carbon steel. This is because as the temperature increases, the molecules in the unblocking agent become more active, thus leading to more rapid corrosion.

[0276] The data shows that at temperatures ≤120℃, the corrosion rates of N80 carbon steel in Examples 1-7 were all less than 20 g / (㎡·h), demonstrating excellent corrosion inhibition effects. This avoids the problem of rapid near-surface reaction that could damage the tubing, and is suitable for deep wells or deep formations. In contrast, Comparative Example 4, lacking a corrosion inhibitor, exhibited a corrosion rate as high as 678.8 g / (㎡·h) on N80 carbon steel, further indicating that the unblocking agents provided in Examples 1-7 have good corrosion control effects.

[0277] Test index 3, acid-rock reaction rate:

[0278] The specific testing method is as follows: First, weigh the dry beakers separately and record the mass as m0; then place the rock (marble or silica particles) in the beaker and weigh it together with the beaker, and record the mass as m1; then the mass of the rock is m1 - m0; then add 10 times the weight of the rock unblocking agent to the beaker.

[0279] Unblocking ability tests were conducted at different temperatures. Specifically, when the test temperature was ≤95℃, the beaker mouth was sealed with a beaker sealing film and then placed in an oven to dissolve. When the test temperature was >95℃, all the blockage material and unblocking agent in the beaker were poured into a high-temperature aging tank lined with polytetrafluoroethylene, sealed, and then placed in an oven to dissolve. All samples were dissolved for 30 minutes, i.e., the rock dissolved in the unblocking agent for 30 minutes. Then, the mixture in the beaker or high-temperature aging tank was poured out and filtered through a 20-mesh sieve. The residue in the beaker or aging tank was also rinsed with water and filtered through a 20-mesh sieve to obtain all the residue. All the residue was transferred to another dry beaker (this beaker was pre-dried and weighed, and the mass was recorded as m2). Then, the beaker containing the residue was placed open in a drying oven at 25℃ and allowed to dry for 12 hours. The beaker and the residue were weighed together, and the mass was recorded as m3. The mass of the residue after drying is m3 - m2.

[0280] The acid-rock reaction rate = [(m1-m0)-(m3-m2)] / 30min, with the unit being g / min. After experimental verification, the acid-rock reaction rates of the unblocking agent, hydrochloric acid (mass fraction 10%), and terpineic acid (a mixture of hydrochloric acid with a mass fraction of 12% and hydrofluoric acid with a mass fraction of 3%) obtained in Examples 1-7 are shown in Table 4.

[0281] Table 4 shows the acid-rock reaction rates (g / min) of the unblocking agent, hydrochloric acid, and terrine obtained in Examples 1-7 on rocks at different temperatures.

[0282]

[0283] As shown in Table 4, the acid-rock reaction of the unblocking agents, hydrochloric acid, and terrine obtained in Examples 1-7 with rocks at different temperatures also exhibits the characteristic of "the higher the temperature, the faster the rate." This is also a macroscopic expression of the law of molecular thermal motion. Specifically, the unblocking agents provided in Examples 1-7 all have relatively low acid-rock reaction rates, with a rate of less than 9.8 g / min for marble and less than 6.9 g / min for silica.

[0284] Under the same temperature conditions, the acid-rock reaction rates of 10% hydrochloric acid, 12% hydrochloric acid and 3% hydrofluoric acid were relatively high, indicating that the unblocking agents provided in Examples 1-7 have a significant function in slowing down the acid-rock reaction, which helps to unblock deep formations and expand the unblocking radius.

[0285] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An oil and gas field unblocking agent, characterized in that, It comprises the following components by weight percentage: 15%–25% multidentate chelate acid complex, 5%–8% fluoride salt, 2%–5% surfactant complex, 1%–3% corrosion inhibitor, 2%–4% miscible solvent, 0.5%–1% dispersant, and the balance being water. The multidentate chelating acid complex includes aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid; The fluoride salt includes ammonium bifluoride and potassium fluorosilicate, wherein the mass ratio of ammonium bifluoride to potassium fluorosilicate is (4.5-5.5):(0.5-1.5). The surfactant complex comprises a quaternary ammonium salt surfactant and a PO-EO block copolymer, wherein the quaternary ammonium salt surfactant comprises molecules with the structure shown in formula (1): , structure (1).

2. The oil and gas field unblocking agent according to claim 1, characterized in that, The mass ratio of aminotrimethylenephosphonic acid to hydroxyethylidene diphosphonic acid is (2.5-3.5):(1.5-2.5).

3. The oil and gas field unblocking agent according to claim 1, characterized in that, The corrosion inhibitor includes an imidazoline derivative and benzotriazole, wherein the mass ratio of the imidazoline derivative to the benzotriazole is (3.5-4.5):(0.5-1.5).

4. The oil and gas field unblocking agent according to claim 1, characterized in that, The mutual solvents include at least one of ethylene glycol butyl ether and diethylene glycol methyl ether.

5. The oil and gas field unblocking agent according to claim 1, characterized in that, The dispersant includes modified sodium polyacrylate, which is prepared by taking 7-9 parts of acrylic acid, 1.5-2.5 parts of 2-acrylamide-2-methylpropanesulfonic acid, and 15-25 parts of water by mass ratio, mixing them, and then adding 0.7%-0.9% of persulfate based on the total mass of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid. The mixture is then heated to 60-70°C and reacted for 3-5 hours.

6. The oil and gas field unblocking agent according to claim 1, characterized in that, The mass ratio of the quaternary ammonium salt surfactant to the PO-EO block copolymer is (2.5-3.5):(1.5-2.5).

7. The oil and gas field unblocking agent according to claim 1, characterized in that, The preparation method of the quaternary ammonium salt surfactant includes the following steps: S1. By weight, take 90-110 parts of 1,1,3,3-tetramethyldisiloxane and 40-80 parts of anhydrous ethanol and place them in a reaction vessel. Stir and then continuously introduce nitrogen gas. S2, Catalysis was carried out by adding platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane; S3. Heat to 70-80℃ and stir continuously. Add 105-115 parts of allyl chloride dropwise and react for 4-8 hours. S4. Cool and filter to remove precipitate. Distill the filtrate under vacuum and collect the fraction at 60-70℃. S5. Dissolve the collected fraction in 235-315 parts of isopropanol, cool to 0-5℃ and stir, then add 150-170 parts of a 30%-35% trimethylamine aqueous solution dropwise. S6. Heat to 60-70℃ and reflux with stirring for 4-6 hours; S7. Cool to 20-30℃ and distill under vacuum to obtain a slurry. S8. Mix the slurry with 180-270 parts of an extractant, wherein the extractant includes at least one of ethyl acetate and diethyl ether. After shaking, washing, extracting, and allowing to stand for separation, remove the organic phase layer and retain the solid and aqueous phase layers. S9. Filter and wash the solid and aqueous phase layers, and vacuum dry the filter cake at 40-50°C for 6-12 hours.

8. The oil and gas field unblocking agent according to claim 1, characterized in that, The molecular weight of the PO-EO block copolymer is 2000-3000.

9. A method for preparing an oil and gas field unblocking agent as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Add water, which accounts for 25% to 35% of the total mass of the oil and gas field unblocking agent, to the reaction vessel by mass percentage. Heat to 55 to 65°C and stir. Then add the measured amount of aminotrimethylene phosphonic acid and hydroxyethylidene diphosphonic acid and continue stirring for 25 to 35 minutes. S2. Add the measured amount of PO-EO block copolymer and continue stirring for 30 to 40 minutes; S3. Add the measured amount of quaternary ammonium salt surfactant and continue stirring for 25-35 minutes; S4. Keep the rotation speed constant, cool down to 20-30℃, then add fluoride salt, corrosion inhibitor, mutual solvent, remaining water and dispersant, and continue stirring for 30-40 minutes.

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