Long-acting plug removal system for oil-water well as well as preparation method and application of long-acting plug removal system

Abstract

The invention discloses an oil-water well long-acting plug removal system and a preparation method and application thereof.The oil-water well long-acting plug removal system is prepared from, by weight, 10%-20% of acid, 1%-3% of acidizing corrosion inhibitor, 1%-3% of clay stabilizer, 0.5%-1% of cleanup additive, 1%-9% of chelating dispersant and the balance water, and the weight ratio of the acid to the acidizing corrosion inhibitor to the clay stabilizer to the cleanup additive to the chelating dispersant is 100%. According to the long-acting plug removal system for the oil-water well, through the synergistic effect of various auxiliaries, various plugs caused by organic scales, inorganic scales and the like in a stratum are effectively removed, the permeability of stratum rocks is remarkably improved, the plug removal effect is remarkable, the effect is stable, the action distance is long, and the plug removal range is wide; the corrosion to a shaft is small, and clay expansion can be effectively prevented, so that damage to the shaft and a stratum is reduced; easily precipitated metal ions can be effectively chelated and dispersed, and secondary precipitation is prevented, so that the blockage removal effect is further improved.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development technology, specifically relating to a long-term unblocking system for oil and water wells, its preparation method, and its application. Background Technology

[0002] With the continuous development of oilfields, the problem of oil and water well blockage has become increasingly prominent, becoming one of the key factors restricting the efficient development and stable production of oilfields. During the production process, improper intrusion of external fluids such as injected water, drilling fluid, completion fluid, and fracturing fluid, as well as the deposition of organic matter such as colloids, asphaltene, and paraffin in formation fluids, and the precipitation of inorganic matter such as inorganic salt scale, corrosion products, and clay minerals, often cause complex blockage in the near-wellbore area. This leads to a significant reduction in formation permeability, a decrease in oil well production, an increase in water injection pressure in water wells, and a sharp reduction in water injection volume, seriously affecting the normal production and ultimate recovery rate of oilfields.

[0003] Currently, the main technologies used domestically and internationally to address oil and water well blockage include acidizing, pressure cracking, hydraulic oscillation, microbial, and bioenzymatic methods. Among these, acidizing is widely used due to its broad applicability and relatively simple construction, but it suffers from several technical drawbacks: traditional acids (such as hydrochloric acid, hydrofluoric acid, and terrine) are highly corrosive to formation rocks and wellbore tubing, easily causing secondary damage; the rapid reaction of acids with the formation results in a short effective range, making deep unblocking difficult; and secondary precipitation (such as fluorosilicates and hydroxides) easily occurs after acidizing, leading to re-blockage and a short effective period.

[0004] Fracturing and fracturing technology improves formation permeability by creating artificial fractures in the formation. However, the construction process is complex and costly, and there are risks such as fracture closure, sand plugging, and formation sand production. Especially for low-permeability and ultra-low-permeability reservoirs, the fracturing effect is often difficult to achieve effectively, resulting in poor economic efficiency.

[0005] While physical methods such as hydraulic oscillation unblocking and ultrasonic unblocking cause little damage to the formation and are simple to implement, they suffer from problems such as rapid energy decay, small radius of action, and short effective period, making it difficult to achieve long-term unblocking.

[0006] In recent years, bio-enzyme declogging technology has gradually attracted attention due to its advantages such as being environmentally friendly and non-corrosive. However, it has shortcomings such as long working time, limited effectiveness in declogging complex blockages, and high cost, which limits its widespread application.

[0007] In summary, existing oil and water well unblocking technologies generally suffer from the following problems: First, their effectiveness in unblocking organic-inorganic composite blockages is limited, making it difficult to achieve thorough and long-term unblocking; second, traditional chemical unblocking agents are highly corrosive, pose a high risk of environmental pollution, and cause secondary damage, resulting in insufficient environmental friendliness; third, existing unblocking technologies generally have a short effective period, requiring frequent operations, leading to poor economic efficiency and failing to meet the long-term needs of stable production and increased efficiency in oilfields. Therefore, developing an efficient, environmentally friendly, and long-lasting oil and water well unblocking system and its preparation method has become an urgent technical challenge to be solved in the current oilfield development field. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a long-term unblocking system for oil and water wells, its preparation method, and its application. This system effectively resolves the blockage problem in oil and water wells, improves oil well production and water injection efficiency, and uses environmentally friendly and biodegradable components to reduce damage to the reservoir and wellbore.

[0009] A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in the following weight percentages: acid 10-20%, acidizing corrosion inhibitor 1-3%, clay stabilizer 1-3%, drainage aid 0.5-1%, chelating dispersant 1-9%, and the balance being water.

[0010] Preferably, the clay stabilizer is a mixture of at least one of cationic polyacrylamide, KCl, AlCl3, polyquaternary ammonium salt, and ammonium chloride with an alkyl glycoside quaternary ammonium salt in any mass ratio.

[0011] Preferably, the alkyl glycoside quaternary ammonium salt is prepared by the following method: using isopropanol as a solvent, 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) and nonionic alkyl glycoside (APG) are mixed in a molar ratio of 1:1 and added to the mixture. The mixture is stirred and reacted at 90°C for 5 hours, and the solvent is removed by vacuum distillation to obtain the alkyl glycoside quaternary ammonium salt.

[0012] Preferably, the acidification corrosion inhibitor is a mixture of oleic acid or octadecylamine and Mannich base quaternary ammonium salt at a mass ratio of 1:3.

[0013] Preferably, the Mannich base quaternary ammonium salt is prepared by the following method: using anhydrous ethanol as a solvent, hydrochloric acid solution is added dropwise to ethylenediamine to adjust the pH value to 4-7, and then formaldehyde and acetophenone are added sequentially in a molar ratio of ethylenediamine:formaldehyde:acetophenone = 1:1:1. The mixture is stirred at a constant temperature of 20-80°C for 4-8 hours to obtain the Mannich base; then, the Mannich base and benzyl chloride are mixed in a molar ratio of 1:(1.1-1.2) and reacted at 20-80°C for 4-5 hours to obtain the Mannich base quaternary ammonium salt.

[0014] Preferably, the chelating dispersant is at least one of hydroxyethylidene diphosphate, diethylenetriaminepentaacetic acid, citric acid, tetrasodium 3-hydroxy-2,2-iminodisuccinate, and aminotriacetic acid, mixed with at least one of sodium polyacrylate, polyepoxysuccinic acid, hydrolyzed polymaleic anhydride, aminotrimethylphosphonic acid, and acrylate-ethyl acrylate-itaconic acid copolymer in any mass ratio.

[0015] Preferably, the discharge aid is a mixture of at least one of sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate, sodium oleate, sodium stearate, and monosodium glutamate with one of ethanol and ethylene glycol in any mass ratio.

[0016] Preferably, the acid is at least one of aminosulfonic acid and acetic acid, or a mixture of at least one of aminosulfonic acid and acetic acid with hydrochloric acid.

[0017] The preparation method of the long-term unblocking system for oil and water wells is as follows: under stirring conditions, acid is first added to water, followed by acidification corrosion inhibitor, clay stabilizer, drainage aid, and chelating dispersant in sequence, and stirred at room temperature until dissolved.

[0018] The method of using the long-term unclogging system for oil and water wells includes the following steps: (1) Perform backwashing of the well, using 1.5 times the volume of clean water to flush the well wall until the water color at the inlet and outlet is consistent; (2) Inject the long-term unblocking system into the oil and water wells to dissolve inorganic scale and organic blockages and improve reservoir permeability; (3) Inject 1.0-1.5 times the volume of clean water into the wellbore to push the unblocking system into the deep formation and ensure that it comes into full contact with the blockage. (4) Well shut-in reaction 4-8 hours; (5) Open the wellhead and drain the reaction products and residual unblocking system.

[0019] Preferably, in step (2), the injection volume of the unblocking system = π × (acidification radius - drill bit radius) × oil layer thickness × porosity, where the units of acidification radius, drill bit radius, and oil layer thickness are all m, and the unit of porosity is π.

[0020] Advantages of this invention: (1) The long-term unblocking system for oil and water wells provided by the present invention can effectively remove various blockages caused by organic and inorganic scale in the formation through the synergistic effect of various additives, significantly improve the permeability of the formation rock, and achieve remarkable unblocking effect; (2) The long-term unblocking system for oil and water wells provided by the present invention has stable function, long working distance, and wide unblocking range; it has low corrosivity to the wellbore and can effectively prevent clay expansion, thereby reducing damage to the wellbore and formation; it can effectively chelate and disperse easily precipitated metal ions, prevent secondary precipitation, and further improve the unblocking effect. (3) The unblocking system provided by the present invention uses environmentally friendly components, has little impact on the environment, and the backflow liquid can be directly introduced into the ground system; (4) The unblocking system provided by the present invention has strong adaptability and is applicable to oil and water well blockage caused by various scales such as organic scale, inorganic scale, and mixed scale. By increasing oil well production and water injection efficiency, it can extend the oil well production cycle and bring significant economic benefits to oilfield development. Attached Figure Description

[0021] Figure 1 CT scan images of core sample 1 before and after acid treatment using the unblocking system described in Example 1; Figure 2 CT scan images of core sample No. 2 before and after acid treatment using the unblocking system described in Example 1; Figure 3 CT scan images of core sample No. 3 before and after acid treatment using the unblocking system described in Example 2; Figure 4 CT scan images of core sample No. 4 before and after acid treatment using the unblocking system described in Example 2; Figure 5 CT scan images of core sample No. 5 before and after acid treatment using the unblocking system described in Example 3; Figure 6 CT scan images of core sample No. 6 before and after acid treatment using the unblocking system described in Example 3; Figure 7 CT scan images of core sample No. 7 before and after acid treatment using the unblocking system described in Example 3; Figure 8 CT scan images of core sample No. 8 before and after acid treatment using the unblocking system described in Example 4; Figure 9 CT scan images of core sample No. 9 before and after acid treatment using the unblocking system described in Example 4; Figure 10 CT scan images of core sample No. 10 before and after acid treatment using the unblocking system described in Example 4; Figure 11 This is the result of the corrosion rate test. Detailed Implementation

[0022] The polyquaternary ammonium salt used in this embodiment of the invention is polyquaternary ammonium salt-10 from Guangzhou Jiayuan Chemical Co., Ltd.

[0023] Example 1 A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in parts by weight: 15% hydrochloric acid, 5% acetic acid, 1% acidizing corrosion inhibitor, 2% clay stabilizer, 1% drainage aid, 1% chelating dispersant, and the balance being water. The acidification corrosion inhibitor is a mixture of oleic acid and Mannich base quaternary ammonium salt in a mass ratio of 1:3. The Mannich base quaternary ammonium salt is prepared by the following method: using anhydrous ethanol as a solvent, hydrochloric acid solution is added dropwise to ethylenediamine to adjust the pH value to 4, and then formaldehyde and acetophenone are added sequentially in a molar ratio of ethylenediamine:formaldehyde:acetophenone = 1:1:1. After stirring at a constant temperature of 20°C for 8 hours, Mannich base is obtained. Then, Mannich base and benzyl chloride are mixed in a molar ratio of 1:1.1 and reacted at 20°C for 5 hours to obtain Mannich base quaternary ammonium salt.

[0024] The clay stabilizer is a mixture of cationic polyacrylamide and alkyl glycoside quaternary ammonium salt in an equal mass ratio. The alkyl glycoside quaternary ammonium salt is prepared by the following method: using isopropanol as a solvent, 3-chloro-2-hydroxypropyltrimethylammonium chloride and nonionic alkyl glycoside are mixed in a molar ratio of 1:1 and added to the mixture. The mixture is stirred and reacted at 90°C for 5 hours. The solvent is removed by vacuum distillation to obtain the alkyl glycoside quaternary ammonium salt. The drainage aid is a mixture of sodium oleate and ethanol in equal mass ratios; The chelating dispersant is a mixture of hydroxyethylidene diphosphate and sodium polyacrylate in equal mass ratio; The preparation method of the long-term unblocking system for oil and water wells is as follows: under stirring conditions, acid is first added to water, followed by acidification corrosion inhibitor, clay stabilizer, drainage aid, and chelating dispersant in sequence, and stirred at room temperature until dissolved.

[0025] Example 2 Aminosulfonic acid was used instead of hydrochloric acid, and everything else was the same as in Example 1.

[0026] Example 3 A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in parts by weight: 5% hydrochloric acid, 15% aminosulfonic acid, 1% acidizing corrosion inhibitor, 2% clay stabilizer, 1% drainage aid, 1% chelating dispersant, and the balance being water; the rest is the same as in Example 1.

[0027] Example 4 A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in parts by weight: 10% hydrochloric acid, 10% aminosulfonic acid, 1% acidizing corrosion inhibitor, 2% clay stabilizer, 1% drainage aid, 1% chelating dispersant, and the balance being water; the rest is the same as in Example 1.

[0028] Example 5 A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in parts by weight: acetic acid 20%, acidizing corrosion inhibitor 3%, clay stabilizer 1%, drainage aid 0.5%, chelating dispersant 4%, and the balance being water; The acidification corrosion inhibitor is a mixture of octadecylamine and Mannich base quaternary ammonium salt in a mass ratio of 1:3. The Mannich base quaternary ammonium salt is prepared by the following method: using anhydrous ethanol as a solvent, hydrochloric acid solution is added dropwise to ethylenediamine to adjust the pH to 7, and then formaldehyde and acetophenone are added sequentially in a molar ratio of ethylenediamine:formaldehyde:acetophenone = 1:1:1. After stirring at 80°C for 4 hours, Mannich base is obtained. Then, Mannich base and benzyl chloride are mixed in a molar ratio of 1:1.2 and reacted at 80°C for 4 hours to obtain Mannich base quaternary ammonium salt. The clay stabilizer is a mixture of KCl, AlCl3 and alkyl glycoside quaternary ammonium salt in a mass ratio of 1:1:1, and the alkyl glycoside quaternary ammonium salt is the same as that in Example 1. The drainage aid is a mixture of sodium stearate and ethylene glycol in equal mass ratios; The chelating dispersant is a mixture of citric acid and polyepoxysuccinic acid in equal mass ratio; The preparation method of the long-term unblocking system for oil and water wells is the same as that in Example 1.

[0029] Example 6 A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in parts by weight: 10% aminosulfonic acid, 2% acidizing corrosion inhibitor, 3% clay stabilizer, 1% drainage aid, 9% chelating dispersant, and the balance being water; The acidification corrosion inhibitor is a mixture of oleic acid and Mannich base quaternary ammonium salt in a mass ratio of 1:3. The Mannich base quaternary ammonium salt is prepared by the following method: using anhydrous ethanol as a solvent, hydrochloric acid solution is added dropwise to ethylenediamine to adjust the pH value to 6, and then formaldehyde and acetophenone are added sequentially in a molar ratio of ethylenediamine:formaldehyde:acetophenone = 1:1:1. After stirring at a constant temperature of 40°C for 7 hours, Mannich base is obtained. Then, Mannich base and benzyl chloride are reacted in a molar ratio of 1:1.1 at 40°C for 4 hours to obtain Mannich base quaternary ammonium salt. The clay stabilizer is a mixture of polyquaternary ammonium salt and alkyl glycoside quaternary ammonium salt in equal mass ratio. The alkyl glycoside quaternary ammonium salt is prepared by the following method: using isopropanol as solvent, 3-chloro-2-hydroxypropyltrimethylammonium chloride and nonionic alkyl glycoside are mixed in a molar ratio of 1:1 and added to the mixture. The mixture is stirred and reacted at 90°C for 5 hours. The solvent is removed by vacuum distillation to obtain the alkyl glycoside quaternary ammonium salt. The excretion aid is a mixture of monosodium glutamate and ethanol in equal mass ratio; The chelating dispersant is a mixture of tetrasodium 3-hydroxy-2,2-iminodisuccinate and acrylate-ethyl acrylate-itaconic acid copolymer in equal mass ratio; The preparation method of the long-term unblocking system for oil and water wells is the same as that in Example 1.

[0030] Example 7 A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in parts by weight: 2% aminosulfonic acid, 8% hydrochloric acid, 2% acidizing corrosion inhibitor, 2% clay stabilizer, 0.5% drainage aid, 2% chelating dispersant, and the balance being water. The acid corrosion inhibitor mentioned herein is the same as that in Example 1; The clay stabilizer is a mixture of ammonium chloride and alkyl glycoside quaternary ammonium salt in an equal mass ratio, and the alkyl glycoside quaternary ammonium salt is the same as in Example 1; The drainage aid is a mixture of sodium dodecylbenzenesulfonate and ethanol in an equal mass ratio; The chelating dispersant is a mixture of aminotriacetic acid and hydrolyzed polymaleic anhydride in equal mass ratio; The preparation method of the long-term unblocking system for oil and water wells is the same as that in Example 1.

[0031] Example 8 A long-term unblocking system for oil and water wells, based on a 100% weight ratio, consists of the following raw materials in parts by weight: 10% aminosulfonic acid, 3% acidizing corrosion inhibitor, 1% clay stabilizer, 0.5% drainage aid, 0.8% chelating dispersant, and the balance being water; The acid corrosion inhibitor and clay stabilizer mentioned herein are the same as those in Example 1; The drainage aid is a mixture of calcium dodecylbenzenesulfonate and ethanol in an equal mass ratio; The chelating dispersant is a mixture of diethylenetriaminepentaacetic acid and aminotrimethylphosphonic acid in equal mass ratio; The preparation method of the long-term unblocking system for oil and water wells is the same as that in Example 1.

[0032] Performance testing 1. Permeability testing of rock cores The permeability of the core was detected by core displacement experiment. The permeability measured by the base fluid (prepared formation water) was the baseline permeability K0, i.e. the permeability before unblocking. The permeability measured by the unblocking system was K. The results are shown in Table 1. Table 1. Permeability test results As shown in Table 1, the permeability of the core improved after the unblocking system was injected, indicating that the unblocking system has a good unblocking effect. It also shows that the unblocking system does not produce secondary precipitation during the unblocking process and has low damage to the core.

[0033] 2. Crack width detection CT scans were used to examine the fracture widths of cores 1-10 in the above-mentioned core displacement experiments before and after injection of the aforementioned unblocking system (i.e., before and after acidizing), corresponding to the fracture widths injected with the base fluid and the unblocking system, respectively. The results are shown in […]. Figures 1-10 and Table 2, where, Figure 1-10 The numbers in the code are the crack numbers; Table 2. Statistical Table of Core Fracture Width Variation .

[0034] 3. Retarding performance testing Core dissolution experiments were conducted at different time points using sulfamic acid and hydrochloric acid, respectively. Formation rock powder was mixed with acid at a mass ratio of 1:10. The weight of the core samples before and after the reaction was measured using the weight loss method at different time points. The dissolution rate was then calculated, as follows: (1) Dry the rock powder at 100℃ to constant weight; (2) Weigh 5.00g of rock powder that has been constant in weight and put it into a beaker. Then add 50mL of prepared 10% hydrochloric acid solution and 50mL of aminosulfonic acid solution to the beaker. Stir with a glass rod until the sample is completely wetted so that the acid solution reacts fully with the rock powder. (3) Place the beaker containing acid and rock powder into an oven at 40°C to start the reaction and record the dissolution time; (4) After the reaction has reached the predetermined time, remove the beaker, filter the reaction mixture, and rinse the rock powder with distilled water until the filtrate is neutral; (5) Dry the filter residue at 100°C to constant weight and record the mass as W2; (6) Calculate the dissolution rate R of the rock powder, R = (5.00 - W2) / 5.00 × 100% In the formula: R—dissolution rate, in %; W2—mass of rock powder after reaction, in g; The etching was performed using the method described above for 0.5h, 1h, 2h, 4h, 8h, 16h, and 24h respectively; the etching rates at different times are shown in the figure. Figure 11 ; Depend on Figure 11It can be seen that the dissolution rate of hydrochloric acid increases rapidly in a short period of time, from 14.58% in 0.5 hours to 17.85% in 24 hours, while the dissolution rate of aminosulfonic acid increases more slowly, gradually rising from 10.56% in 0.5 hours to 17.56% in 24 hours. This phenomenon indicates that aminosulfonic acid has a significant slowing effect. This slowing effect allows aminosulfonic acid to dissolve the rock core more uniformly in practical applications, avoiding problems such as excessive local dissolution caused by excessively rapid reactions. At the same time, it extends the dissolution distance of the acid system on the rock core and increases the acidification radius. This mainly illustrates that aminosulfonic acid has a better slowing effect compared with hydrochloric acid used in existing technologies. Therefore, the acid in the unblocking system of this invention can be aminosulfonic acid, or hydrochloric acid can be added to aminosulfonic acid.

Claims

1. A long-term unclogging system for oil and water wells, characterized in that: Based on a 100% weight ratio, it consists of the following raw materials in the following weight percentages: acid 10-20%, acidification corrosion inhibitor 1-3%, clay stabilizer 1-3%, drainage aid 0.5-1%, chelating dispersant 1-9%, and the balance being water.

2. The long-term unblocking system for oil and water wells according to claim 1, characterized in that: The clay stabilizer is a mixture of at least one of cationic polyacrylamide, KCl, AlCl3, polyquaternary ammonium salt, and ammonium chloride with an alkyl glycoside quaternary ammonium salt in any mass ratio.

3. The long-term unclogging system for oil and water wells according to claim 2, characterized in that: The alkyl glycoside quaternary ammonium salt is prepared by the following method: using isopropanol as a solvent, 3-chloro-2-hydroxypropyltrimethylammonium chloride and nonionic alkyl glycoside are mixed at a molar ratio of 1:1 and added to the mixture. The mixture is stirred and reacted at 90°C for 5 hours, and the solvent is removed by vacuum distillation to obtain the alkyl glycoside quaternary ammonium salt.

4. The long-term unclogging system for oil and water wells according to claim 1, characterized in that: The acidification corrosion inhibitor is a mixture of oleic acid or octadecylamine and Mannich base quaternary ammonium salt at a mass ratio of 1:

3.

5. The long-term unblocking system for oil and water wells according to claim 4, characterized in that: The Mannich base quaternary ammonium salt is prepared by the following method: using anhydrous ethanol as a solvent, hydrochloric acid solution is added dropwise to ethylenediamine to adjust the pH value to 4-7. Then, formaldehyde and acetophenone are added sequentially in a molar ratio of ethylenediamine:formaldehyde:acetophenone = 1:1:

1. The mixture is stirred at a constant temperature of 20-80℃ for 4-8 hours to obtain the Mannich base. Then, the Mannich base and benzyl chloride are mixed in a molar ratio of 1:(1.1-1.2) and reacted at 20-80℃ for 4-5 hours to obtain the Mannich base quaternary ammonium salt.

6. The long-term unclogging system for oil and water wells according to claim 1, characterized in that: The chelating dispersant is at least one of hydroxyethylidene diphosphate, diethylenetriaminepentaacetic acid, citric acid, tetrasodium 3-hydroxy-2,2-iminodisuccinate, and aminotriacetic acid, mixed with at least one of sodium polyacrylate, polyepoxysuccinic acid, hydrolyzed polymaleic anhydride, aminotrimethylphosphonic acid, and acrylate-ethyl acrylate-itaconic acid copolymer in any mass ratio.

7. The long-term unblocking system for oil and water wells according to claim 1, characterized in that: The discharge aid is a mixture of at least one of sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate, sodium oleate, sodium stearate, and monosodium glutamate with one of ethanol and ethylene glycol in any mass ratio.

8. The long-term unclogging system for oil and water wells according to claim 1, characterized in that: The acid is at least one of aminosulfonic acid and acetic acid, or a mixture of at least one of aminosulfonic acid and acetic acid with hydrochloric acid.

9. The preparation method of the long-term unblocking system for oil and water wells according to claim 1, characterized in that: The preparation method is as follows: under stirring conditions, acid is first added to water, followed by acidification corrosion inhibitor, clay stabilizer, drainage aid, and chelating dispersant in sequence, and stirred at room temperature until dissolved.

10. The method of using the long-term unblocking system for oil and water wells as described in claim 1, characterized in that: Includes the following steps: (1) Perform backwashing of the well, using 1.5 times the volume of clean water to flush the well wall until the water color at the inlet and outlet is consistent; (2) Inject the long-term unblocking system into the oil and water wells; (3) Displace the wellbore with 1.0-1.5 times its volume of clean water; (4) Well shut-in reaction 4-8 hours; (5) Open the wellhead and drain the reaction products and residual unblocking system.

Images