Non-acidic plug removal liquid system for plug removal of oil and gas well and preparation method of non-acidic plug removal liquid system

Abstract

The invention discloses a non-acidic plug removal liquid system for plug removal of an oil and gas well. The non-acidic plug removal liquid system comprises the following components in percentage by mass: 20-40% of a targeted substitution agent, 10-15% of a complexing agent, 15-20% of a solubilizer, 10-20% of a penetrant, 10-25% of a dispersing agent and 20-45% of a cosolvent, wherein the targeted substitution agent is obtained by taking a polyene polyamine compound, a polymer depolymerizing agent, an organic antioxidant and alcohol amine as main raw materials and carrying out reaction. The non-acidic unblocking liquid system can unblock polymer, scale and greasy filth debris composite blockages at the same time, has a high dissolution rate, always keeps neutral in the unblocking process, is low in static corrosion rate, has a wide use temperature range, is safe and environmentally friendly, and can be applied to the fields of unblocking of wellbores and reservoir fractures and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemicals, and in particular relates to a non-acidic plugging-removing fluid system for oil and gas wells and a preparation method thereof. Background Art

[0002] During the construction of continuous tubing, drilling plugs, etc., the wellbore is often blocked or seriously polluted near the wellbore due to the accumulation and precipitation of chemical materials and wellbore return materials, which may even cause the drill to get stuck. Some wells can continue to operate by repeatedly lifting and lowering the continuous tubing to replace grinding shoes and other drilling tools, which greatly increases the difficulty of the operation and reduces the construction efficiency. Some wells still need acid injection to unblock, and continuous tubing is required for acid injection to accurately act on the specified depth. However, the acid liquid corrodes the continuous tubing and drilling plug tools severely, greatly shortening the service life of the equipment. In addition, there are many safety and environmental risks in the transportation, preparation, construction, and residual acid return of the acid liquid.

[0003] Conventional acid has a fast acid-rock reaction speed and poor targeted unblocking, and has poor unblocking effect on blockages caused by hydrophobic associating polymers (drag reducers, temporary plugging agents). At the same time, when dealing with reservoir pollution, conquering inorganic insoluble scale is also the key to improving the efficiency of unblocking technology. In some reservoirs, the presence of calcium sulfate in large quantities greatly increases the difficulty of mining due to its high hygroscopicity and solubility in glycerol. In addition, over time, calcium sulfate gradually solidifies to form gypsum-like deposits, which are more stubborn than ordinary dirt and difficult to remove. Faced with such complex conditions, traditional acidic unblocking agents cannot effectively decompose such hard scale layers, resulting in limited increase in oil field production. At the same time, traditional acidic unblocking fluids will also destroy the rock skeleton, easily collapse, and cause great damage to the reservoir, and are not suitable for acid-sensitive reservoirs.

[0004] Invention patent CN117757453B discloses a neutral composite unblocking agent, which introduces fatty alcohol polyoxyethylene ether penetrant, and minerals in the reservoir such as clay minerals (montmorillonite, illite, etc.) can be adsorbed with fatty alcohol polyoxyethylene ether, resulting in a decrease in the effective concentration of the surfactant. At the same time, mineral particles may also cause a decrease in reservoir permeability due to physical blockage, which affects the unblocking effect to a certain extent; in addition, the sulfur-containing dicarboxylic acid introduced as a complexing agent may have chemical stability problems, and sulfur atoms are easily oxidized under complex conditions of use, which may also cause the performance of the unblocking agent to decrease; and the application temperature of the obtained unblocking agent is 60-80°C, which is not suitable for unblocking high and low temperature wells, and has certain limitations. Patent CN104194758B discloses a neutral unblocking agent composition for oil field production wells, which can remove scales such as barium sulfate, calcium sulfate, and strontium sulfate that cannot be eliminated by pickling and conventional well fluids, but cannot solve the wellbore blockage problem caused by complex polymer entanglement, and the unblocking process involved is lengthy, usually taking dozens of hours or even longer to completely solve the wellhead blockage problem.

[0005] In summary, existing neutral and non-acidic plugging removal fluids still have problems such as narrow applicable temperature range, great impact on the environment, long plugging removal time, poor plugging removal effect, and inability to solve the problems of multiple blockages deposited and blocked at the same time. Further exploration and provision of new non-acidic plugging removal fluid systems can effectively remove wellbore blockages caused by polymer and inorganic salt scale inhibition and bridge plug debris accumulation while meeting environmental protection requirements and not causing corrosion damage to the wellbore, and can effectively broaden the operating temperature range to greatly extend the service life of the coiled tubing, which has important research and application significance. Summary of the invention

[0006] The main purpose of the present invention is to provide a non-acidic plugging removal fluid system for oil and gas wells in view of the problems and shortcomings of the prior art. The non-acidic plugging removal fluid system has a high dissolution rate for composite pluggings such as polymers, scales and sludge debris, and always remains neutral during the plugging removal process. The static corrosion rate is low and the operating temperature range is wide. The non-acidic plugging removal fluid system can simultaneously remove complex wellbore blockages caused by the accumulation of inorganic salts such as sludge debris, calcium, magnesium, barium and strontium, and organic substances such as polyacrylamide and polyvinyl alcohol. The non-acidic plugging removal fluid system has no corrosion to pipelines and equipment, meets safety and environmental protection requirements, and can be applied to the fields of wellbore and reservoir fracture plugging removal.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A non-acidic unblocking liquid system for unblocking oil and gas wells comprises the following components in percentage by weight: 20-40% of a targeting substituent, 10-15% of a complexing agent, 15-20% of a solubilizing agent, 10-20% of a penetrant, 10-25% of a dispersant and 20-45% of a cosolvent; wherein the targeting substituent is obtained by reacting polyene polyamine compounds, polymer depolymerizing agents, organic antioxidants and alcohol amines as main raw materials.

[0009] In the above scheme, the components and their mass percentages in the targeted attack type substituent include: 25-40% polyene polyamine compound, 20-40% polymer depolymerizing agent, 15-30% organic antioxidant, and 20-40% alcohol amine.

[0010] Furthermore, the polyene polyamine compound is one or more of diethylenetriamine, triethylenetetramine, and ethylenetriamine; the polymer depolymerizing agent is one or more of ethylenediaminetetraacetic acid tetrasodium salt (EDTA), ethylenediaminetetraacetic acid disodium salt (EDDA), and ethylenediaminetetra(methylenephosphonic acid) pentasodium salt; the organic antioxidant is one or more of 2,6-di-tert-butyl-p-cresol, 1,3,5-tris(2-hydroxy-4-tert-butylphenyl)benzene, N,N-dibenzylhydroxylamine, di-tert-butyl-4-methylphenol ether ester, and tert-butyl hydroxybenzoate; and the alcohol amine is one or more of diglycolamine, triglycolamine, diethanolamine, and triethanolamine.

[0011] In the above scheme, the preparation method of the targeted attack substituent includes: 1) adding a polyene polyamine compound into a reaction container under a protective atmosphere and performing a heating and stirring treatment; 2) adding an organic antioxidant, and then sequentially adding a polymer depolymerizing agent and an alcohol ammonium, and performing a heating reaction (polymerization reaction) to obtain the targeted attack substituent.

[0012] In the above scheme, in the heating and stirring treatment step of step 1), the speed adopted is 100-200r / min, the temperature is 50-70, and the time is 10-20min.

[0013] In the above scheme, the heating reaction step in step 2) includes: heating to 70-90° C. within 2-5 minutes and keeping the temperature for reaction for 2-3 hours.

[0014] The targeted attack substituent formed according to the above scheme has strong molecular structure stability, which makes the targeted attack substituent have excellent thermal stability. At the same time, the flexible chain segment is introduced into the molecular chain, so that it still maintains good flexibility at low temperature, improves its performance at low temperature, avoids crystallization at low temperature, and effectively enhances its temperature application range. The formed targeted attack substituent can accurately identify and act on polymer blockages, and at the same time form a coordination complex with specific chemical bonds on the surface of the blockage, destroy the chain structure of the polymer through chemical reaction, reduce its viscosity and aggregation, and decompose the polymer into smaller and more flowable molecules; in addition, the targeted attack substituent can also reduce the interfacial tension between polymer fragments and the surrounding medium, making it easier to disperse in the fluid and prevent redeposition.

[0015] In the above scheme, the complexing agent is one of EDTA and sodium epoxysuccinate.

[0016] In the above scheme, the solubilizer is one or a mixture of hydroxypropyl coco betaine, hydroxyethyl galactomannan, and diethanol laurate.

[0017] In the above scheme, the penetrant is one or a mixture of mercaptopropanol, tripropyl phosphate, and modified sodium salt of di-sec-octyl sulfosuccinate.

[0018] In the above scheme, the dispersant is one or a mixture of ethylene bisstearamide, ethylene-acrylic acid copolymer, acrylic acid-methyl acrylate copolymer.

[0019] In the above scheme, the co-solvent is one or a mixture of dimethylformamide, N,N-dimethylformamide (DMF), and methyl benzoate.

[0020] In the above scheme, the preparation method of the non-acidic plugging removal liquid comprises: adding the targeted substituent, complexing agent, solubilizer, penetrant, dispersant and co-solvent weighed in proportion to a reaction kettle in sequence under stirring, and stirring evenly at room temperature.

[0021] The multifunctional non-acidic plugging-removing liquid system for oil and gas well plugging removal of the present invention uses targeted substituents, complexing agents, solubilizing agents, penetrants, dispersants and co-solvents as main raw materials. The introduced solubilizing agents, penetrants and dispersants can synergize with the targeted attacking substituents to effectively improve the dissolution effect on polymer, scale and sludge debris composite pluggings. In addition, the pH value of the present invention is maintained between 7 and 8, belonging to a neutral plugging-removing liquid, which can maintain a low static corrosion rate. The present invention has strong intermolecular forces and thermal stability, and the interaction between the components in the formula remains stable at different temperatures, and no significant physical or chemical changes will occur due to temperature changes, which can effectively broaden the application temperature range. The solubilizer, through its cooperation with the targeted attack type displacer, can ensure that the displacer is effectively dispersed in the medium, thereby improving its transfer efficiency; the dispersant and the penetrant cooperate to help the targeted attack type displacer and other unblocking components to be deeply and evenly distributed in the target area, thereby improving their uniformity and effectiveness; the constructed targeted attack type displacer can act on specific targets in a targeted manner (such as polymer blocking components such as polyacrylamide and polyvinyl alcohol in rocks, etc.).

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The non-acidic plugging removal liquid system of the present invention can simultaneously remove polymer, scale and sludge debris composite pluggings, and has multifunctionality compared to conventional plugging removal liquids;

[0024] 2) The non-acidic plugging removal liquid system of the present invention has a dissolution rate of ≥98% for complex blockages; the pH value is always maintained at 7-8 during the plugging removal process, and the static corrosion rate is <0.05g / m 2 h, no corrosion to pipelines and equipment; temperature is 50-120℃, unblocking time is 8-24h; it meets safety and environmental protection requirements and is particularly suitable for unblocking operations in complex working conditions of oil and gas wells. DETAILED DESCRIPTION

[0025] The technical scheme adopted in the present invention will be clearly and specifically described below by examples and comparative examples, which are only examples of the present invention, do not represent all embodiments, and do not limit the scope of the present invention. The embodiments in the present invention, and those skilled in the art make various changes or modifications according to the present invention, and these equivalent forms also belong to the scope protected by the present invention. Unless otherwise specified, the equipment and reagents used in the present invention are conventional commercial products in the field of the present technology.

[0026] Example 1

[0027] A non-acidic plugging-removing liquid system for oil and gas well plugging removal, the specific preparation steps comprising:

[0028] (1) Preparation of targeted substitution agents;

[0029] Install a stirrer, a thermometer, a condenser and a nitrogen interface at the mouth of a 1000ml three-necked reaction bottle; under nitrogen flow conditions, add 30g of triethylenetetramine into the reaction bottle, start stirring, set the stirring speed to 200r / min, heat to 60°C in a water bath, and stir for 10min; add a mixture of 10g of tert-butyl hydroxybenzoate and 10g of di-tert-butyl-4-methylphenol ether ester into the reaction bottle from the upper mouth of the condenser, then add 15g of triethanolamine and 15g of triglycolamine and 10g of ethylenediaminetetraacetic acid disodium salt (EDDA) and 10g of ethylenediaminetetramethylenephosphonic acid pentasodium salt into the reaction bottle in sequence, then heat to 80°C within 3min, and react at a constant temperature for 2h, during which a polymer is gradually generated;

[0030] (2) Prepare a 500 mL beaker, weigh 10 g EDTA, 15 g hydroxypropyl coco-betaine, 10 g tripropyl phosphate, 10 g ethylene-acrylic acid copolymer (molecular weight 60000-100000 g / mol), 20 g N, N-dimethylformamide (DMF) and 35 g of the targeted attack type substituent prepared in step (1), add them into the beaker, and stir evenly to obtain a non-acidic plugging removal liquid. The obtained non-acidic plugging removal liquid system is evaluated for performance, which specifically includes the following steps:

[0031] (1) Static corrosion rate test

[0032] According to the Sinopec standard "Q / SH CG0129-2021 Technical Requirements for Corrosion Inhibitors for Acidification" 7.3, a static corrosion rate test was carried out. During the test, the obtained non-acidic plugging solution was first added to water for dilution (the same below), and plugging agents with concentrations of 10wt%, 20wt%, and 30wt% were selected respectively. The static hanging plate method was used to evaluate the corrosion of N80 steel sheets. The results showed that the corrosion rates of plugging agents with different concentrations were all lower than 0.05g / m 2 .h, the corrosion rate is 0.04g / m 2 ﹒ h, 0.03g / m 2 ﹒ h, 0.04g / m 2 ﹒ h.

[0033] (2) Dissolution rate test

[0034] The simulated wellbore blockage was prepared according to the mass ratio of polyacrylamide (molecular weight 25 million g / mol): polyvinyl alcohol (molecular weight 200,000 g / mol): calcium carbonate: calcium sulfate: oil sludge and drill cuttings = 4:4:1:2:1. 10 g of the blockage was taken, the volume of the unblocking liquid was 50 mL, the reaction temperature was 50°C, and the reaction time was 24 h. After the reaction, the weight of the insoluble matter was weighed and the dissolution rate was calculated. The results are shown in Table 1.

[0035] Example 2

[0036] A non-acidic plugging-removing liquid system for oil and gas well plugging removal, the specific preparation steps comprising:

[0037] (1) Preparation of targeted substitution agents;

[0038] Install a stirrer, a thermometer, a condenser and a nitrogen interface at the mouth of a 1000ml three-necked reaction bottle; under nitrogen flow conditions, add 15g of diethylenetriamine and 10g of ethylenetriamine into the reaction bottle, start stirring, set the stirring speed to 100r / min, heat to 60°C in a water bath, and stir for 10min; add 15g of 2,6-di-tert-butyl-p-cresol into the reaction bottle from the upper mouth of the condenser, then add 30g of diethanolamine and 40g of disodium ethylenediaminetetraacetic acid (EDDA) into the reaction bottle in sequence, then heat to 80°C within 2-5min, and react at a constant temperature for 3h, during which a polymer is gradually generated;

[0039] (2) Prepare a 500 mL beaker, weigh 10 g of sodium epoxysuccinate, 10 g of hydroxyethyl galactomannan, 5 g of diethyl laurate, 10 g of modified sodium dioctyl sulfosuccinate and 5 g of mercaptopropanol, 10 g of ethylene bisstearamide, 15 g of acrylic acid-methyl acrylate copolymer, 5 g of dimethylformamide, 10 g of methyl benzoate and 20 g of the targeted attack type substituent prepared in step (1) and add them to the beaker. The order of adding the drugs can be disrupted. After stirring evenly, a non-acidic plugging removal liquid can be obtained.

[0040] Referring to the method described in Example 1, the performance of the obtained non-acidic plugging removal liquid system was tested, and the results are as follows:

[0041] The static corrosion rate test results show that the corrosion rates of the plugging removers with different concentrations (10wt%, 20wt%, and 30wt%) are all lower than 0.01g / m 2 h, and the corrosion rate is 0.02g / m 2 ﹒ h, 0.03g / m 2 ﹒ h, 0.04g / m 2 ﹒ h.

[0042] The dissolution rate test results are shown in Table 1.

[0043] Example 3

[0044] A non-acidic plugging-removing liquid system for oil and gas well plugging removal, the specific preparation steps comprising:

[0045] (1) Preparation of targeted substitution agents;

[0046] Install a stirrer, a thermometer, a condenser and a nitrogen interface at the mouth of a 1000ml three-necked reaction bottle; under nitrogen flow conditions, add 20g of diethylenetriamine and 20g of ethylenediethylenetriamine into the reaction bottle, start stirring, set the stirring speed to 150r / min, heat to 60°C in a water bath, and stir for 10min; add 10g of 1,3,5-tris(2-hydroxy-4-tert-butylphenyl)benzene and 5g of N,N-dibenzylhydroxylamine into the reaction bottle from the upper mouth of the condenser, then add 10g of diethanolamine and 10g of triethanolamine, and 25g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA) into the reaction bottle in sequence, then heat to 80°C within 2-5min, and react at a constant temperature for 2.5h;

[0047] (2) Prepare a 500 mL beaker, weigh 10 g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA), 5 g of hydroxyethyl galactomannan, 10 g of diethyl laurate, 15 g of mercaptopropanol, 20 g of acrylic acid-methyl acrylate copolymer, 10 g of N,N-dimethylformamide (DMF), 10 g of methyl benzoate and 20 g of the targeted attack type substituent prepared in step (1), add them into the beaker, and stir evenly to obtain a non-acidic plugging removal liquid.

[0048] Referring to the method described in Example 1, the performance of the obtained non-acidic plugging removal liquid system was tested, and the results are as follows:

[0049] The static corrosion rate test results show that the corrosion rates of the plugging remover with different concentrations (10%, 20%, and 30%) are all lower than 0.05 g / m 2 h, and the corrosion rate is 0.01g / m 2 ﹒ h, 0.03g / m 2 ﹒ h, 0.02g / m 2 ﹒ h.

[0050] The dissolution rate test results are shown in Table 1.

[0051] Comparative Example 1

[0052] A non-acidic plugging-removing liquid system for oil and gas well plugging removal, the specific preparation steps comprising:

[0053] (1) Preparation of targeted substitution agents;

[0054] Install a stirrer, a thermometer and a condenser interface at the mouth of a 1000ml three-necked reaction bottle; under nitrogen flow conditions, add 20g of diethylenetriamine and 20g of ethylenediethylenetriamine into the reaction bottle, start stirring, set the stirring speed to 150r / min, heat to 90°C in a water bath, and stir for 10min; add 10g of 1,3,5-tris(2-hydroxy-4-tert-butylphenyl)benzene and 5g of N,N-dibenzylhydroxylamine into the reaction bottle from the upper mouth of the condenser, then add 10g of diethanolamine and 10g of triethanolamine, and 25g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA) into the reaction bottle in sequence, then heat to 100°C within 2-5min, and react at a constant temperature for 2.5h;

[0055] (2) Prepare a 500 mL beaker, weigh 10 g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA), 5 g of hydroxyethyl galactomannan, 10 g of diethyl laurate, 15 g of mercaptopropanol, 20 g of acrylic acid-methyl acrylate copolymer, 10 g of N,N-dimethylformamide (DMF), 10 g of methyl benzoate and 20 g of the targeted attack type substituent prepared in step (1), add them into the beaker, and stir evenly to obtain a non-acidic plugging removal liquid.

[0056] Referring to the method described in Example 1, the performance of the obtained non-acidic plugging removal liquid system was tested, and the results are as follows:

[0057] The static corrosion rate test results show that the corrosion rates of the plugging removers with different concentrations (10%, 20%, and 30%) are 0.03 g / m 2 ﹒ h, 0.02g / m 2 ﹒ h, 0.04g / m 2 ﹒ h.

[0058] The dissolution rate test results are shown in Table 1.

[0059] Comparative Example 2

[0060] A non-acidic plugging-removing liquid system for oil and gas well plugging removal, the specific preparation steps comprising:

[0061] (1) Preparation of targeted substitution agents;

[0062] Install a stirrer, a thermometer, a condenser and a nitrogen interface at the mouth of a 1000ml three-necked reaction bottle; under nitrogen flow conditions, add 20g of diethylenetriamine and 20g of ethylenediethylenetriamine into the reaction bottle, start stirring, set the stirring speed to 150r / min, heat to 60°C in a water bath, and stir for 10min; add 10g of 1,3,5-tris(2-hydroxy-4-tert-butylphenyl)benzene and 5g of N,N-dibenzylhydroxylamine into the reaction bottle from the upper mouth of the condenser, then add 10g of diethanolamine and 10g of triethanolamine, and 25g of hydrogen peroxide into the reaction bottle in sequence, then heat to 80°C within 2-5min, and react at a constant temperature for 2.5h;

[0063] (2) Prepare a 500 mL beaker, weigh 10 g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA), 5 g of hydroxyethyl galactomannan, 10 g of diethyl laurate, 15 g of mercaptopropanol, 20 g of acrylic acid-methyl acrylate copolymer, 10 g of N,N-dimethylformamide (DMF), 10 g of methyl benzoate and 20 g of the targeted attack type substituent prepared in step (1), add them into the beaker, and stir evenly to obtain a non-acidic plugging removal liquid.

[0064] Referring to the method described in Example 1, the performance of the obtained non-acidic plugging removal liquid system was tested, and the results are as follows:

[0065] The static corrosion rate test results show that the corrosion rates of the plugging remover with different concentrations (10%, 20%, and 30%) are 0.18 g / m 2 ﹒ h, 0.21g / m 2 ﹒ h, 0.19g / m 2 ﹒ h.

[0066] The dissolution rate test results are shown in Table 1.

[0067] Comparative Example 3

[0068] A non-acidic plugging-removing liquid system for oil and gas well plugging removal, the specific preparation steps comprising:

[0069] (1) Preparation of targeted substitution agents;

[0070] Install a stirrer, a thermometer, a condenser and a nitrogen interface at the mouth of a 1000ml three-necked reaction bottle; under nitrogen flow conditions, add 20g of diethylenetriamine and 20g of ethylenediethylenetriamine into the reaction bottle, start stirring, set the stirring speed to 150r / min, heat to 60°C in a water bath, and stir for 10min; add 10g of 1,3,5-tris(2-hydroxy-4-tert-butylphenyl)benzene and 5g of N,N-dibenzylhydroxylamine into the reaction bottle from the upper mouth of the condenser, then add 10g of diethanolamine and 25g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA) into the reaction bottle in sequence, then heat to 80°C within 2-5min, and react at a constant temperature for 2.5h, during which a polymer is gradually generated;

[0071] (2) Prepare a 500 mL beaker, weigh 10 g of tetrasodium ethylenediaminetetraacetic acid (EDTA), 5 g of hydroxyethyl galactomannan, 10 g of diethyl laurate, 15 g of mercaptopropanol, 20 g of acrylic acid-methyl acrylate copolymer, 10 g of N,N-dimethylformamide (DMF), 10 g of methyl benzoate and 20 g of the targeted attack type substituent prepared in (1) and add them into the beaker. The order of adding the drugs can be disrupted. After stirring evenly, a non-acidic deblocking liquid can be obtained.

[0072] Referring to the method described in Example 1, the performance of the obtained non-acidic plugging removal liquid system was tested, and the results are as follows:

[0073] The static corrosion rate test results show that the corrosion rates of the plugging remover with different concentrations (10%, 20%, and 30%) are all lower than 0.05 g / m 2 h, and the corrosion rate is 0.02g / m 2 ﹒ h, 0.03g / m 2 ﹒ h, 0.02g / m 2 ﹒ h.

[0074] The dissolution rate test results are shown in Table 1.

[0075] Comparative Example 4

[0076] A non-acidic plugging-removing liquid system for oil and gas well plugging removal, the specific preparation steps comprising:

[0077] (1) Preparation of targeted substitution agents;

[0078] Install a stirrer, a thermometer, a condenser and a nitrogen interface at the mouth of a 1000ml three-necked reaction bottle; under nitrogen flow conditions, add 20g of diethylenetriamine and 20g of ethylenediethylenetriamine into the reaction bottle, start stirring, set the stirring speed to 150r / min, heat to 60°C in a water bath, and stir for 10min; add 10g of 1,3,5-tris(2-hydroxy-4-tert-butylphenyl)benzene and 5g of N,N-dibenzylhydroxylamine into the reaction bottle from the upper mouth of the condenser, then add 10g of diethanolamine and 10g of triethanolamine, and 25g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA) into the reaction bottle in sequence, then heat to 80°C within 2-5min, and react at a constant temperature for 2.5h, during which a polymer is gradually generated;

[0079] (2) Prepare a 500 mL beaker, weigh 2 g of ethylenediaminetetraacetic acid tetrasodium salt (EDTA), 5 g of hydroxyethyl galactomannan, 10 g of diethyl laurate, 15 g of mercaptopropanol, 20 g of acrylic acid-methyl acrylate copolymer, 10 g of N,N-dimethylformamide (DMF), 10 g of methyl benzoate and 20 g of the targeted attack type substituent prepared in (1) and add them into the beaker. The order of adding the drugs can be disrupted. After stirring evenly, a non-acidic plugging removal liquid can be obtained.

[0080] Referring to the method described in Example 1, the performance of the obtained non-acidic plugging removal liquid system was tested, and the results are as follows:

[0081] The static corrosion rate test results show that the corrosion rates of the plugging remover with different concentrations (10%, 20%, and 30%) are all lower than 0.05 g / m 2 h, and the corrosion rate is 0.03g / m 2 ﹒ h, 0.02g / m 2 ﹒ h, 0.02g / m 2 ﹒ h.

[0082] The dissolution rate test results are shown in Table 1.

[0083] Table 1 Dissolution rate test results

[0084] Serial number Experimental Group Initial mass / g Mass after reaction / g Dissolution rate / % 1 Example 1 10.0000 0.1762 98.24 2 Example 2 10.0000 0.1821 98.18 3 Example 3 10.0000 0.1844 98.16 4 Comparative Example 1 10.0000 1.7911 82.09 5 Comparative Example 2 10.0000 2.5847 74.15 6 Comparative Example 3 10.0000 5.5812 44.19 7 Comparative Example 4 10.0000 4.6215 53.79

[0085] For those skilled in the art, it is easy to improve and embellish the present invention without departing from the technology of the present invention, and these improvements and embellishments also fall within the scope of protection of the present invention. The present invention is not limited to the above-mentioned embodiments, and any changes within the claims of the present invention are covered within the scope of protection.

Claims

1. A non-acidic plugging-removing fluid system for oil and gas well plugging removal, characterized in that: The invention comprises the following components in percentage by weight: 20-40% of a targeting substituent, 10-15% of a complexing agent, 15-20% of a solubilizing agent, 10-20% of a penetrant, 10-25% of a dispersant and 20-45% of a cosolvent; wherein the targeting substituent is obtained by reacting polyene polyamine compounds, polymer depolymerizing agents, organic antioxidants and alcohol amines as main raw materials.

2. The non-acidic plugging removal liquid system according to claim 1, characterized in that: In the targeted attack type substituent, each component and its mass percentage include: 25-40% of polyene polyamine compound, 20-40% of polymer depolymerizing agent, 15-30% of organic antioxidant and 20-40% of alcohol amine.

3. The non-acidic plugging removal liquid system according to claim 1, characterized in that: The polyene polyamine compound is one or more of diethylenetriamine, triethylenetetramine, and ethylenetriamine; the polymer depolymerizing agent is one or more of ethylenediaminetetraacetic acid tetrasodium salt, ethylenediaminetetraacetic acid disodium salt, and ethylenediaminetetramethylenephosphonic acid pentasodium salt; the organic antioxidant is a mixture of one or more of 2,6-di-tert-butyl-p-cresol, 1,3,5-tris(2-hydroxy-4-tert-butylphenyl)benzene, N,N-dibenzylhydroxylamine, di-tert-butyl-4-methylphenol ether ester, and tert-butyl hydroxybenzoate; and the alcohol amine is one or more of diglycolamine, triglycolamine, diethanolamine, and triethanolamine.

4. The non-acidic plugging removal liquid system according to claim 1, characterized in that: The preparation method of the targeted attack type substituent comprises: 1) adding polyene polyamine compounds into a reaction container under a protective atmosphere, and performing heating and stirring treatment; 2) adding an organic antioxidant, and then sequentially adding a polymer depolymerizing agent and alcohol ammonium, and performing heating reaction to obtain the targeted attack type substituent.

5. The non-acidic plugging removal liquid system according to claim 1, characterized in that: The complexing agent is one of EDTA and sodium epoxysuccinate.

6. The non-acidic plugging removal liquid system according to claim 1, characterized in that: The solubilizer is one or a mixture of hydroxypropyl coco betaine, hydroxyethyl galactomannan, and diethanol laurate.

7. The non-acidic plugging removal liquid system according to claim 1, characterized in that: The penetrant is one or a mixture of mercaptopropanol, tripropyl phosphate, and modified sodium salt of di-sec-octyl sulfosuccinate.

8. The non-acidic plugging removal liquid system according to claim 1, characterized in that: The dispersant is one or a mixture of ethylene bisstearamide, ethylene-acrylic acid copolymer, acrylic acid-methyl acrylate copolymer.

9. The non-acidic plugging removal liquid system according to claim 1, characterized in that: The co-solvent is one or a mixture of dimethylformamide, N,N-dimethylformamide and methyl benzoate.

10. The method for preparing the non-acidic plugging removal liquid according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: adding the targeted substituent, complexing agent, solubilizer, penetrant, dispersant and co-solvent weighed in proportion into a reaction kettle in sequence under stirring, and stirring evenly under room temperature.