High-temperature-resistant and low-corrosion oil and gas well plug remover and preparation method thereof

Abstract

The application relates to the technical field of oil and gas well plug removal agents, in particular to an anti-high-temperature and low-corrosion oil and gas well plug removal agent and a preparation method thereof. The anti-high-temperature and low-corrosion oil and gas well plug removal agent comprises the following raw materials: a main dissolving agent, a high-temperature-resistant penetrating and swelling agent, a dispersion stabilizer, a neutral corrosion inhibitor, a thickening agent, an environment-friendly solvent and deionized water. The preparation method of the anti-high-temperature and low-corrosion oil and gas well plug removal agent is as follows: the dispersion stabilizer and the neutral corrosion inhibitor are added into the deionized water, stirred uniformly at room temperature, then the main dissolving agent, the environment-friendly solvent and the thickening agent are added, heated, stirred uniformly, then the high-temperature-resistant penetrating and swelling agent is added, stirred uniformly at constant temperature, the pH value of the system is adjusted, cooled to room temperature, filtered, and the anti-high-temperature and low-corrosion oil and gas well plug removal agent is obtained. The anti-high-temperature and low-corrosion oil and gas well plug removal agent prepared by the application has the advantages of high high-temperature plug removal capacity, low corrosion rate, high closed cup flash point, good safety in construction storage and transportation, high biodegradation rate and the like, and can meet the oil field environmental protection construction standard.

Description

Technical Field

[0001] This application relates to the field of oil and gas well unblocking agents, and more specifically, it relates to a high-temperature resistant and low-corrosion oil and gas well unblocking agent and its preparation method. Background Technology

[0002] After long-term continuous exploitation, oil and gas fields are prone to the formation of hard, gelatinous composite blockages on the inner walls of old wells and in the near-wellbore zone. These blockages are formed by the cross-linking and solidification of polymer micelles, asphaltene, colloids, and inorganic scale. These blockages obstruct oil and gas flow channels, significantly reducing reservoir conductivity and causing a continuous decline in well productivity. The industry commonly uses chemical unblocking agents for wellbore treatment.

[0003] Currently, commonly used mainstream unblocking systems are mainly divided into three categories, all of which have significant drawbacks: The first category is conventional acid systems represented by hydrochloric acid and arginine. These systems only have a certain dissolving ability for inorganic scale and are difficult to break down and degrade cross-linked polymers, asphaltene, and other organic micelles. The systems are highly acidic and contain chloride ions, which can cause severe corrosion reactions with N80 carbon steel and stainless steel tubing, casing, and downhole tools, significantly shortening the service life of the tubing string. The second category is aromatic hydrocarbon and alcohol-ether compound organic solvent unblocking agents. Although they can dissolve organic blockage components to a slight degree, they lack the ability to complex and strip inorganic scale, resulting in poor overall dissolution of complex blockages. Furthermore, the raw material costs are high, and the agents themselves have an irritating odor and a certain degree of toxicity. The third type is the commercially available composite unblocking agent. Although it can treat both organic and inorganic plugging media, its formulation still retains chloride-containing salts or highly corrosive acidic components. It lacks targeted penetration and large-molecule chain-breaking functional structures, resulting in slow dissolution and long treatment cycles. Furthermore, the system lacks long-lasting dispersing and stabilizing components, making the dissolved plugging products prone to re-flocculation and deposition, leading to a short unblocking effectiveness period and making it unsuitable for the green and low-damage well workover requirements of deep, high-temperature, old wells. Therefore, developing a high-temperature resistant and low-corrosion oil and gas well unblocking agent and its preparation method to achieve efficient dissolution, low metal corrosion, and chloride-free environmental friendliness has become a key issue that urgently needs to be addressed in the current oil and gas well unblocking agent technology field. Summary of the Invention

[0004] To address the technical problems mentioned in the background section, this application provides a high-temperature resistant and low-corrosion oil and gas well unblocking agent and its preparation method.

[0005] Firstly, this application provides a high-temperature resistant and low-corrosion oil and gas well unblocking agent, employing the following technical solution: A high-temperature and low-corrosion resistant oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30-40% main solvent, 10-15% high-temperature resistant penetrating swelling agent, 3-5% dispersing stabilizer, 1-2% neutral corrosion inhibitor, 1-2% thickener, 9-14% environmentally friendly solvent, and the balance being deionized water.

[0006] Preferably, the main solvent is composed of a composite aminocarboxylate and a hydroxycarboxylate in a mass ratio of 10-12:3-5.

[0007] Preferably, the composite aminocarboxylate is composed of alkyl amino polycarboxylate and degradable aminocarboxylate in a mass ratio of 5-8:1-3.

[0008] Preferably, the hydroxycarboxylic acid salt is one or more of sodium gluconate, sodium glycolate, and sodium lactate.

[0009] Preferably, the alkylamino polycarboxylic acid salt is one or more of ethylenediaminetetraacetic acid tetrasodium, diethylenetriaminepentaacetic acid pentasodium, and hydroxyethylethylenediaminetriacetic acid trisodium.

[0010] Preferably, the degradable aminocarboxylate is tetrasodium glutamate diacetate and / or trisodium methylglycine diacetate.

[0011] Preferably, the preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano halloysite were added to a reaction vessel and stirred until homogeneous at 50-60°C to obtain a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor to adjust the pH of the system. The mixture was stirred at high speed until homogeneous. After cooling, isopropanol was added dropwise and stirring was continued to obtain a high-temperature resistant penetrating swelling agent.

[0012] Preferably, the mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol is 3-6:2-4:1-2:20-30:0.5-1.2:0.3-0.5:1-2.

[0013] Preferably, the neutral corrosion inhibitor is composed of naphthenic acid imidazoline, oleic acid imidazoline and triethanolamine borate in a mass ratio of 8-12:2-5:5-8.

[0014] Preferably, the thickener is hydroxyethyl cellulose and / or carboxymethyl hydroxyethyl cellulose.

[0015] Preferably, the dispersant stabilizer is one or more of sodium polyaspartate, sodium polyepoxysuccinate, sodium polyacrylate, and sodium maleic acid-acrylic acid copolymer.

[0016] Preferably, the environmentally friendly solvent is one or more of dipropylene glycol butyl ether, dipropylene glycol dimethyl ether, diethylene glycol tert-butyl ether, ethylene glycol diacetate, and propylene glycol diacetate.

[0017] Secondly, this application also provides a method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent, employing the following technical solution: A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant and a neutral corrosion inhibitor to deionized water and stir until homogeneous. Then add the main solvent, an environmentally friendly solvent, and a thickener. Heat the mixture to 40-50°C and stir until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir until homogeneous at a constant temperature. Adjust the pH of the system to 2.5-4.5, cool, and filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0018] In summary, this application has the following beneficial effects: This application optimizes the compound system of complex aminocarboxylate in the main solvent and combines it with hydroxycarboxylate for synergistic chelation. This can compensate for the defects of the chelation ability decay and scale dissolution efficiency of single aminocarboxylate at high temperatures, and achieve efficient dissociation of carbonate scale, sulfate scale and asphaltenes complex scale. It significantly improves the overall scale dissolution capacity of the unblocking agent in the 160℃ deep high-temperature downhole environment and ensures its stable and efficient unblocking effect under high temperature conditions.

[0019] This application employs a ternary synergistic modification method involving nano-haloysite inorganic rigid loading, hydroxyethylidene diphosphonic acid chelating corrosion inhibitor, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane. This results in a modified high-temperature resistant penetrating swelling agent exhibiting excellent high-temperature stability, low corrosivity, and deep penetration swelling performance. Nano-haloysite, with its highly heat-resistant tubular structure, forms a rigid framework that effectively inhibits high-temperature thermal degradation of the agent, improving the system's high-temperature tolerance and dispersion uniformity. Hydroxyethylidene diphosphonic acid forms a protective film on metal equipment surfaces, significantly reducing the agent's corrosion rate, while simultaneously chelating scale ions to aid in the removal of downhole scale. 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane connects the inorganic filler and organic components, solving the problem of nanoparticle agglomeration, constructing a stable cross-linked network, and enhancing the agent's penetration capacity. The synergistic effect of these three components effectively overcomes the shortcomings of traditional swelling agents, such as easy high-temperature failure, high corrosion, and shallow unblocking properties, making it suitable for the harsh high-temperature conditions of oil and gas wells and ensuring the efficient and long-lasting operation of the unblocking agent.

[0020] This application constructs a neutral corrosion inhibitor system consisting of a ternary compound of naphthenic acid imidazoline, oleic acid imidazoline, and triethanolamine borate. These three components form a complementary adsorption film on the metal pipe surface. Naphthenic acid imidazoline provides basic film protection, oleic acid imidazoline enhances film integrity, and triethanolamine borate improves the film's high-temperature stability. Their synergistic effect effectively inhibits the electrochemical corrosion of N80 downhole pipes by high-temperature media, controlling the corrosion rate to an extremely low level. This maximizes the service life of the downhole pipes while ensuring unblocking efficiency. By combining suitable dispersants and environmentally friendly solvents, the overall reagent formulation system is optimized, improving the high-temperature compatibility and system stability of each component and preventing reagent stratification failure at high temperatures. Furthermore, the entire process uses biodegradable green raw materials, abandoning highly corrosive inorganic acid systems, giving the unblocking agent both high flash point storage and transportation safety and excellent biodegradability. The overall formula forms a closed-loop synergistic effect system among its components, which can be adapted to the complex downhole conditions of deep high-temperature oil and gas wells. It also has multiple advantages such as efficient unblocking, low corrosion, construction safety and green environmental protection, making it suitable for large-scale downhole operations in oil fields. Detailed Implementation

[0021] The present application will be further described in detail below with reference to the embodiments.

[0022] The naphthenic acid imidazoline used in the embodiments and comparative examples of this application was purchased from Wuhan Jiyesheng Chemical Co., Ltd.; oleic acid imidazoline was purchased from Hubei Xingyan New Material Technology Co., Ltd.; triethanolamine borate ester was purchased from Jinan Yuno Chemical Co., Ltd.; sodium polyaspartate was purchased from Shandong Xima Supply Chain Management Co., Ltd.; hydroxyethylidene diphosphonic acid was purchased from Shandong Shenglilong Chemical Technology Co., Ltd.; 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane was purchased from Hubei Qiansheng Biotechnology Co., Ltd.; sodium polyepoxysuccinate was purchased from Shandong Xuchen Chemical Technology Co., Ltd.; sodium maleic acid-acrylic acid copolymer was purchased from Wuhan Jiyesheng Chemical Co., Ltd.; nano halloysite (particle size: 3000 mesh) was purchased from Beijing Jingtu Hengsheng Chemical Technology Co., Ltd.; nano silica (particle size: 3000 mesh) was purchased from Puyang Zhongxin Chemical Co., Ltd.; polyethylene glycol 2000 was purchased from Jinan Quanchi New Material Co., Ltd.; carboxymethyl hydroxyethyl cellulose (viscosity: 60,000) was purchased from Wuhan Kangqiong Biomedical Technology Co., Ltd.; hydroxyethyl cellulose (viscosity: 100,000) was purchased from Kaimaoxing (Hebei) Cellulose Co., Ltd.

[0023] Examples 1-3 provide a high-temperature resistant and low-corrosion oil and gas well unblocking agent and its preparation method.

[0024] Example 1 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium gluconate in a mass ratio of 10:3, and the composite aminocarboxylate is composed of tetrasodium ethylenediaminetetraacetate and tetrasodium glutamate diacetate in a mass ratio of 5:1. The neutral corrosion inhibitor is composed of imidazoline naphthenic acid, imidazoline oleate, and triethanolamine borate in a mass ratio of 8:2:5. The dispersant stabilizer is sodium polyaspartate. The environmentally friendly solvent is dipropylene glycol butyl ether, and the thickener is hydroxyethyl cellulose.

[0025] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-haloite were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.2 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was then stirred at 500 rpm at 50°C. After 20 minutes, the temperature was lowered to 25°C, and isopropanol was added dropwise over a period of 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol was 3:2:1:20:0.5:0.3:1.

[0026] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0027] Example 2 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 35% main solvent, 12% high-temperature resistant permeable swelling agent, 4% dispersant stabilizer, 1.5% neutral corrosion inhibitor, 1.5% thickener, 10% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium glycolate in a mass ratio of 11:4. The composite aminocarboxylate is composed of pentasodium diethylenetriaminepentaacetate and trisodium methylglycine diacetate in a mass ratio of 7:2. The neutral corrosion inhibitor is composed of naphthenic acid imidazoline, oleic acid imidazoline, and triethanolamine borate in a mass ratio of 10:4:7. The dispersant stabilizer is sodium polyepoxysuccinate. The environmentally friendly solvent is ethylene glycol diacetate, and the thickener is hydroxyethyl cellulose.

[0028] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-haloite were added to a reactor. The mixture was stirred at 250 rpm for 25 minutes at 55°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.6 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was stirred at 700 rpm for 30 minutes at 55°C. After cooling to 30°C, isopropanol is added dropwise over 12 minutes. The mixture is stirred at 150 rpm for 15 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and isopropanol is 4:3:1.5:25:0.8:0.4:1.5.

[0029] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 300 rpm for 25 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 45°C and stir at 300 rpm for 15 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 300 rpm for 15 minutes. Adjust the pH of the system to 3.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0030] Example 3 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 40% main solvent, 15% high-temperature resistant permeable swelling agent, 5% dispersant stabilizer, 2% neutral corrosion inhibitor, 2% thickener, 14% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium lactate in a mass ratio of 12:5. The composite aminocarboxylate is composed of trisodium hydroxyethyl ethylenediamine triacetate and tetrasodium glutamate diacetate in a mass ratio of 8:3. The neutral corrosion inhibitor is composed of naphthenic acid imidazoline, oleic acid imidazoline, and triethanolamine borate in a mass ratio of 12:5:8. The dispersant stabilizer is sodium maleic acid-acrylic acid copolymer. The environmentally friendly solvent is propylene glycol diacetate, and the thickener is carboxymethyl hydroxyethyl cellulose.

[0031] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-haloite were added to a reaction vessel. The mixture was stirred at 300 rpm for 30 minutes at 60°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 5.0 with a 5 wt% glacial acetic acid aqueous solution. The mixture was stirred at 800 rpm at 60°C. After 40 minutes, the temperature was lowered to 35°C, and isopropanol was added dropwise over a period of 15 minutes. The mixture was stirred at 200 rpm for another 20 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol was 6:4:2:30:1.2:0.5:2.

[0032] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Dispersant stabilizer and neutral corrosion inhibitor were added to deionized water. The mixture was stirred at 400 rpm for 30 minutes at room temperature until homogeneous. Then, the main solvent, environmentally friendly solvent, and thickener were added. The temperature was raised to 50°C, and the mixture was stirred at 400 rpm for 20 minutes until homogeneous. Then, a high-temperature resistant penetrating swelling agent was added, and the mixture was stirred at 400 rpm for 20 minutes at a constant temperature. The pH of the system was adjusted to 4.5 using 10 wt% aminosulfonic acid aqueous solution and 5 wt% triethanolamine solution as pH adjusters. The mixture was cooled to room temperature and filtered through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0033] Comparative Example 1 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of tetrasodium ethylenediaminetetraacetate and sodium gluconate in a mass ratio of 10:3; the neutral corrosion inhibitor is composed of imidazoline naphthenate, imidazoline oleate, and triethanolamine borate in a mass ratio of 8:2:5; the dispersant stabilizer is sodium polyaspartate; the environmentally friendly solvent is dipropylene glycol butyl ether; and the thickener is hydroxyethyl cellulose.

[0034] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-haloite were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.2 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was then stirred at 500 rpm at 50°C. After 20 minutes, the temperature was lowered to 25°C, and isopropanol was added dropwise over a period of 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol was 3:2:1:20:0.5:0.3:1.

[0035] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0036] Comparative Example 2 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of tetrasodium glutamate diacetate and sodium gluconate in a mass ratio of 10:3; the neutral corrosion inhibitor is composed of naphthenic acid imidazoline, oleic acid imidazoline, and triethanolamine borate in a mass ratio of 8:2:5; the dispersant stabilizer is sodium polyaspartate; the environmentally friendly solvent is dipropylene glycol butyl ether; and the thickener is hydroxyethyl cellulose.

[0037] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-haloite were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.2 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was then stirred at 500 rpm at 50°C. After 20 minutes, the temperature was lowered to 25°C, and isopropanol was added dropwise over a period of 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol was 3:2:1:20:0.5:0.3:1.

[0038] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0039] Comparative Example 3 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium gluconate in a mass ratio of 10:3, and the composite aminocarboxylate is composed of tetrasodium ethylenediaminetetraacetate and tetrasodium glutamate diacetate in a mass ratio of 5:1. The neutral corrosion inhibitor is composed of imidazoline naphthenic acid, imidazoline oleate, and triethanolamine borate in a mass ratio of 8:2:5. The dispersant stabilizer is sodium polyaspartate. The environmentally friendly solvent is dipropylene glycol butyl ether, and the thickener is hydroxyethyl cellulose.

[0040] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano halloysite were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water and hydroxyethylidene diphosphonic acid were added to the precursor, and the pH of the system was adjusted to 4.2 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was stirred at 500 rpm for 20 minutes at 50°C. The temperature was then lowered to 25°C, and isopropanol was added dropwise over 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, and isopropanol was 3:2:1:20:0.8:1.

[0041] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0042] Comparative Example 4 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium gluconate in a mass ratio of 10:3, and the composite aminocarboxylate is composed of tetrasodium ethylenediaminetetraacetate and tetrasodium glutamate diacetate in a mass ratio of 5:1. The neutral corrosion inhibitor is composed of imidazoline naphthenic acid, imidazoline oleate, and triethanolamine borate in a mass ratio of 8:2:5. The dispersant stabilizer is sodium polyaspartate. The environmentally friendly solvent is dipropylene glycol butyl ether, and the thickener is hydroxyethyl cellulose.

[0043] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano halloysite were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.2 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was stirred at 500 rpm for 20 minutes at 50°C. The temperature was then lowered to 25°C, and isopropanol was added dropwise over 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and isopropanol was 3:2:1:20:0.8:1.

[0044] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0045] Comparative Example 5 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium gluconate in a mass ratio of 10:3, and the composite aminocarboxylate is composed of tetrasodium ethylenediaminetetraacetate and tetrasodium glutamate diacetate in a mass ratio of 5:1. The neutral corrosion inhibitor is composed of imidazoline oleate and triethanolamine borate in a mass ratio of 10:5. The dispersant stabilizer is sodium polyaspartate. The environmentally friendly solvent is dipropylene glycol butyl ether, and the thickener is hydroxyethyl cellulose.

[0046] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-haloite were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.2 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was then stirred at 500 rpm at 50°C. After 20 minutes, the temperature was lowered to 25°C, and isopropanol was added dropwise over a period of 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol was 3:2:1:20:0.5:0.3:1.

[0047] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0048] Comparative Example 6 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium gluconate in a mass ratio of 10:3, and the composite aminocarboxylate is composed of tetrasodium ethylenediaminetetraacetate and tetrasodium glutamate diacetate in a mass ratio of 5:1. The neutral corrosion inhibitor is composed of imidazoline naphthenic acid and triethanolamine borate in a mass ratio of 10:5. The dispersant stabilizer is sodium polyaspartate. The environmentally friendly solvent is dipropylene glycol butyl ether, and the thickener is hydroxyethyl cellulose.

[0049] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-haloite were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.2 with a 5 wt% aqueous solution of glacial acetic acid. The mixture was then stirred at 500 rpm at 50°C. After 20 minutes, the temperature was lowered to 25°C, and isopropanol was added dropwise over a period of 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol was 3:2:1:20:0.5:0.3:1.

[0050] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0051] Comparative Example 7 A high-temperature resistant and low-corrosion oil and gas well unblocking agent comprises the following raw materials by weight percentage: 30% main solvent, 10% high-temperature resistant permeable swelling agent, 3% dispersant stabilizer, 1% neutral corrosion inhibitor, 1% thickener, 9% environmentally friendly solvent, and the balance being deionized water. The main solvent is composed of a composite aminocarboxylate and sodium gluconate in a mass ratio of 10:3, and the composite aminocarboxylate is composed of tetrasodium ethylenediaminetetraacetate and tetrasodium glutamate diacetate in a mass ratio of 5:1. The neutral corrosion inhibitor is composed of imidazoline naphthenic acid, imidazoline oleate, and triethanolamine borate in a mass ratio of 8:2:5. The dispersant stabilizer is sodium polyaspartate. The environmentally friendly solvent is dipropylene glycol butyl ether, and the thickener is hydroxyethyl cellulose.

[0052] The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano-silica were added to a reaction vessel. The mixture was stirred at 200 rpm for 20 minutes at 50°C until homogeneous, yielding a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor. The pH of the system was adjusted to 4.2 with a 5 wt% glacial acetic acid aqueous solution. The mixture was then stirred at 500 rpm at 50°C. After 20 minutes, the temperature was lowered to 25°C, and isopropanol was added dropwise over a period of 10 minutes. The mixture was stirred at 100 rpm for another 10 minutes to obtain a high-temperature resistant penetrating swelling agent. The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano silica, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol was 3:2:1:20:0.5:0.3:1.

[0053] A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent includes the following preparation steps: Add a dispersant stabilizer and a neutral corrosion inhibitor to deionized water. Stir at 200 rpm for 20 minutes at room temperature until homogeneous. Then add the main solvent, environmentally friendly solvent, and thickener. Heat to 40°C and stir at 200 rpm for 10 minutes until homogeneous. Add a high-temperature resistant penetrating swelling agent and stir at 200 rpm for 10 minutes at a constant temperature. Adjust the pH of the system to 2.5 using a 10 wt% aminosulfonic acid aqueous solution and a 5 wt% triethanolamine solution as pH adjusters. Cool to room temperature and filter through a 100-mesh filter to obtain a high-temperature resistant and low-corrosion oil and gas well unblocking agent.

[0054] Performance testing To verify the comprehensive application performance of the high-temperature and low-corrosion oil and gas well unblocking agent prepared in this application, and to clarify the influence of each raw material component and compounding ratio on the high-temperature unblocking ability, corrosion inhibition performance, safety performance and environmental performance of the unblocking agent, a unified standard performance test was carried out on the unblocking agent samples prepared in Examples 1-3 and Comparative Examples 1-7. The specific test items, test standards, test methods and test results are as follows. Standardized preparation method for standard mixed scale samples: To accurately reflect the complex blockage conditions of carbonate scale, sulfate scale, and organic bitumen in oil and gas wells, a standardized, reproducible mixed scale sample is prepared. The mass percentages of each component in the standard mixed scale sample are: calcium carbonate scale 70wt%, barium sulfate scale 10wt%, and asphaltene deposit scale 20wt%. The standardized preparation process for each individual component is as follows: (1) Calcium carbonate scale: Analytical grade calcium carbonate powder was ground through a 200-mesh standard sieve and dried at 105℃ for 24 hours until constant weight was achieved for later use. (2) Barium sulfate scale: Barium sulfate powder is purified from industrial barite ore with a purity of ≥98.5%, ground through a 300-mesh standard sieve, and dried at 105℃ for 24 hours until constant weight is achieved for later use. (3) Standardized asphaltene deposits: Raw material source: Crude oil from the wellhead of heavy oil wells in Shengli Oilfield, China. Basic crude oil indicators: gum content 18.2 wt%, asphaltene content 6.7 wt%. Extraction and preparation steps: ① Take 100g of crude oil, add 400mL of n-heptane, let stand at room temperature in the dark for 48h, filter and collect the insoluble precipitate crude asphaltene; ② Place the crude asphaltene in toluene and heat under reflux to dissolve, filter while hot to remove inorganic mud and sand impurities, and remove the toluene solvent by rotary evaporation to obtain pure asphaltene; ③ Remove the solvent from the n-heptane filtrate by rotary evaporation to obtain crude oil gum; ④ Mix the gum and pure asphaltene at a mass ratio of 3:1 according to the average mass ratio of oilfield deposits, dry at 120℃ to remove residual solvent, grind through a 200-mesh sieve to obtain standardized gum asphaltene deposits; Specifications: The number average molecular weight range of this standard gum asphaltene deposit is 1200-2800, the softening point is 72-78℃, and the batch-to-batch component deviation is ≤3%.

[0055] The dried calcium carbonate powder, barium sulfate powder, and standardized asphalt scale powder were mechanically mixed in a mass ratio of 70:10:20, pressed into flake scale, dried at 105℃ to constant weight, and a uniform batch of standard mixed scale samples were obtained for all scale dissolution parallel tests.

[0056] Scale dissolution rate: High-temperature scale dissolution performance was tested according to industry standard SY / T 5886-2018 "Performance Evaluation Method for Acidifying Working Fluids". 2.00g of the dried and constant-weight standard mixed scale sample was accurately weighed and placed in a high-pressure reactor. 100mL of the unblocking agent sample to be tested was added. After sealing the high-pressure reactor, the temperature was raised to 160℃ and allowed to stand for 4 hours. After the reaction, the sample was removed, and the undissolved scale was separated by filtration. The remaining solid scale was dried at 105℃ to constant weight and then weighed. The total scale dissolution rate was calculated according to the formula: Scale dissolution rate (%) = (initial scale mass - remaining scale mass) / initial scale mass × 100%; Corrosion rate: Referring to the national standard GB / T 18175-2014 "Determination of corrosion inhibition performance of water treatment agents - Rotary hanging plate method", the test conditions were optimized in combination with the working conditions of downhole pipes in oil and gas wells. Commonly used N80 steel hanging plates were selected. The hanging plate size was 50mm×25mm×2mm. The test conditions were: test temperature 160℃, rotation speed 75rpm, immersion time 24h. After the test, the corrosion products on the surface of the hanging plate were removed, and the plate was dehydrated and dried with anhydrous ethanol and weighed. The uniform corrosion rate of the steel plate was calculated. Flash point: Tested according to national standard GB / T 5208-2008 "Determination of flash point - rapid equilibrium closed cup method"; Biodegradability: Tested according to the national standard GB / T 21801-2008 "Rapid Biodegradability of Chemicals - Respiratory Measurement Method", with the 28-day biodegradation rate as the evaluation index; The specific test results are shown in Table 1.

[0057] Table 1 Performance parameters of high-temperature and low-corrosion unblocking agents for oil and gas wells in Examples 1-3 and Comparative Examples 1-7 As shown in Table 1, the high-temperature resistant and low-corrosion oil and gas well unblocking agent prepared in this application exhibits excellent comprehensive performance. The unblocking agents prepared in Examples 1-3 all achieve a scale dissolution rate of over 96% under high-temperature conditions of 160℃, demonstrating strong high-temperature unblocking capabilities. Simultaneously, the corrosion rate of N80 steel is as low as 0.005-0.009 mm / a, with a corrosion inhibition effect far superior to the comparative examples, maximizing the protection of downhole tubing and casing. Furthermore, the flash points are all above 120℃, ensuring good safety during construction and storage. The biodegradability rates are all above 79%, meeting oilfield environmental protection construction standards. The synergistic effect among the components of the formulation used in this application is suitable for the needs of high-temperature oil and gas well field operations, demonstrating significant application advantages.

[0058] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-temperature resistant and low-corrosion-resistant oil and gas well unblocking agent, characterized in that, The raw materials include the following weight percentages: 30-40% main solvent, 10-15% high-temperature resistant penetrating swelling agent, 3-5% dispersing stabilizer, 1-2% neutral corrosion inhibitor, 1-2% thickener, 9-14% environmentally friendly solvent, and the balance being deionized water; The main solvent is composed of a complex aminocarboxylate and a hydroxycarboxylate; The composite aminocarboxylate is composed of alkyl amino polycarboxylate and degradable aminocarboxylate; The hydroxycarboxylic acid salt is one or more of sodium gluconate, sodium glycolate, and sodium lactate; The alkylamino polycarboxylic acid salt is one or more of the following: tetrasodium ethylenediaminetetraacetate, pentasodium diethylenetriaminepentaacetate, and trisodium hydroxyethylethylenediaminetriacetate. The degradable aminocarboxylate is tetrasodium glutamate diacetate and / or trisodium methylglycine diacetate; The preparation method of the high-temperature resistant penetrating swelling agent includes the following preparation steps: Cocamidopropyl betaine, polyethylene glycol 2000, and nano halloysite were added to a reaction vessel and stirred evenly at 50-60°C to obtain a precursor. Deionized water, hydroxyethylidene diphosphonic acid, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added to the precursor to adjust the pH of the system. The mixture was stirred evenly at high speed, cooled, and isopropanol was added dropwise. Stirring was continued to obtain a high-temperature resistant penetrating swelling agent. The neutral corrosion inhibitor is composed of naphthenic acid imidazoline, oleic acid imidazoline, and triethanolamine borate.

2. The high-temperature resistant and low-corrosion oil and gas well unblocking agent according to claim 1, characterized in that, The mass ratio of the complex aminocarboxylate to the hydroxycarboxylate in the main solvent is 10-12:3-5.

3. The high-temperature resistant and low-corrosion oil and gas well unblocking agent according to claim 1, characterized in that, The mass ratio of alkyl amino polycarboxylate to degradable aminocarboxylate in the composite aminocarboxylate is 5-8:1-3.

4. The high-temperature resistant and low-corrosion oil and gas well unblocking agent according to claim 1, characterized in that, The mass ratio of naphthenic acid imidazoline, oleic acid imidazoline and triethanolamine borate in the neutral corrosion inhibitor is 8-12:2-5:5-8.

5. The high-temperature resistant and low-corrosion oil and gas well unblocking agent according to claim 1, characterized in that, The mass ratio of cocamidopropyl betaine, polyethylene glycol 2000, nano halloysite, deionized water, hydroxyethylidene diphosphonic acid, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and isopropanol is 3-6:2-4:1-2:20-30:0.5-1.2:0.3-0.5:1-2.

6. The high-temperature resistant and low-corrosion oil and gas well unblocking agent according to claim 1, characterized in that, The dispersing stabilizer is one or more of sodium polyaspartate, sodium polyepoxysuccinate, sodium polyacrylate, and sodium maleic acid-acrylic acid copolymer.

7. The high-temperature resistant and low-corrosion oil and gas well unblocking agent according to claim 1, characterized in that, The environmentally friendly solvent is one or more of dipropylene glycol butyl ether, dipropylene glycol dimethyl ether, diethylene glycol tert-butyl ether, ethylene glycol diacetate, and propylene glycol diacetate.

8. A method for preparing a high-temperature resistant and low-corrosion oil and gas well unblocking agent as described in any one of claims 1-7, characterized in that, The preparation steps include the following: Add dispersant and neutral corrosion inhibitor to deionized water, stir well, then add main solvent, thickener and environmentally friendly solvent, heat to 40-50℃, stir well, add high temperature resistant penetrating swelling agent, stir well at constant temperature, adjust the pH of the system to 2.5-4.5, cool, filter, and obtain a high temperature resistant and low corrosion oil and gas well unblocking agent.

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