A sol treatment agent, its preparation method and its application in unblocking polymer injection wells

Abstract

The present invention belongs to the field of oil and gas production technology and discloses a sol treatment agent, its preparation method, and its application in declogging polymer injection wells. The sol treatment agent comprises the following components, by weight: 3% to 5% sodium persulfate, 2% to 3% ferrous sulfate, 0.05% to 0.1% nonylphenol polyoxyethylene ether, 0.3% to 0.5% imidazoline quaternary ammonium salt, 0.03% to 0.05% fluorocarbon surfactant, 0.5% to 0.6% ammonium chloride, 0.05% to 0.1% methanesulfonic acid, and the balance is water. The sol treatment agent is used as the primary agent in combination with an oil displacement agent and an acidic declogging agent. It can be used to declog blocks caused by displacement agents, heavy crude oil components, clay particles, and the like, restoring injectivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas production, and relates to a sol treatment agent, a preparation method thereof, and its application in unblocking polymer injection wells, and is suitable for unblocking polymer injection wells blocked by gel. Background Art

[0002] Block 1 of the Haiwaihe Oilfield is a conventional heavy oil reservoir developed through waterflooding. Due to reservoir heterogeneity, waterflooding has become increasingly difficult to improve development outcomes. Deep flooding began in 2010, with a cumulative injection of 1.93 million cubic meters of gel in 29 well groups. The average injection pressure increased by 3.5 MPa from 9.5 MPa before flooding to 13.0 MPa, significantly improving both vertical and horizontal sweep characteristics. The gelled flooding agent has a viscosity of 8,000-10,000 mPa·s, encapsulating clay particles, heavy crude oil components, and organic impurities in the water. This forms a strong and deformable plug that accumulates near the wellbore, increasing injection pressure and resulting in under-injection or non-injection, hindering development effectiveness. To address this issue, there is an urgent need to develop a treatment agent capable of dissolving the flooding agent and a method for removing the plugging.

[0003] The Chinese patent for the deep acidizing and unblocking method of oxidizing composite acid for acidizing and unblocking water injection wells (application number: 201410854255.4) uses active water, acidic unblocking liquid, and main component acid liquid to be injected into the water injection well to be unblocked in sequence, and then two cement trucks are used to simultaneously inject the oxidizing unblocking agent liquid and the acidic unblocking liquid into the water injection well to be unblocked. It is suitable for general water injection well blockages and does not involve polymer injection wells.

[0004] A Chinese patent for an acidizing declogging agent (application number: 201710020278.9) is made of inorganic acid, organic acid, chelating agent, oil washing agent, corrosion inhibitor, clay stabilizer, demulsifier, penetrant, mutual solvent, and surfactant in a certain proportion. It is suitable for declogging new wells and declogging old wells for sewage treatment. It is not very effective for blockages caused by factors such as asphaltene and colloid in heavy oil wells.

[0005] A Chinese patent for a three-in-one acidizing agent and its application method for oil well unblocking (Application No. 201810319466.6) utilizes a polybasic organic acid, a precipitation inhibitor, an iron ion chelating agent, an anti-swelling agent, an anti-acid slag agent, a corrosion inhibitor, hydrogen fluoride, a demulsifier, and a waterproofing agent. The agent is suitable for treating inorganic and organic scale blockages in general oil wells. However, it is less effective against blockages caused by asphaltene and colloid in heavy oil wells.

[0006] When a formation becomes blocked, injection pressure increases, resulting in insufficient or incomplete injection, and the inability to meet normal injection rates at the injection line pressure, leading to a decline in well production. Currently used gel-based plugging removal technology simply uses a sol. While it can dissolve gel near the wellbore, it cannot dissolve inorganic blockages and has a short lifespan. Summary of the Invention

[0007] To overcome the shortcomings of the existing technology, the present invention provides a sol treatment agent, its preparation method, and its application in unclogging polymer injection wells. The agent is suitable for unclogging injection wells clogged with gel. It can be used to remove blockages caused by profile control agents, heavy crude oil components, clay particles, and other contaminants, restoring injectivity.

[0008] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0009] A sol treatment agent comprises the following components in percentage by weight: 3% to 5% sodium persulfate, 2% to 3% ferrous sulfate, 0.05% to 0.1% nonylphenol polyoxyethylene ether, 0.3% to 0.5% imidazoline quaternary ammonium salt, 0.03% to 0.05% fluorocarbon surfactant, 0.5% to 0.6% ammonium chloride, 0.05% to 0.1% methanesulfonic acid, and the balance is water.

[0010] The preparation method of the sol treatment agent is as follows: sodium persulfate, ferrous sulfate, nonylphenol polyoxyethylene ether, imidazoline quaternary ammonium salt, fluorocarbon surfactant, ammonium chloride, and methanesulfonic acid are sequentially added to water and stirred evenly to obtain the sol treatment agent.

[0011] The sol treatment agent prepared by the above preparation method is used for unblocking polymer injection wells.

[0012] The above-mentioned sol treatment agent is specifically used for unblocking polymer injection wells, which are suitable for unblocking polymer injection wells where the injection pressure is high due to gel blockage and the geological injection cannot be met. The sol treatment agent is used as the main agent in combination with an oil displacement agent and an acidic unblocking agent.

[0013] The specific method of using the above-mentioned sol treatment agent to remove blockage in polymer injection wells is as follows:

[0014] 1) Carry out positive flushing of the water injection well to the bottom of the artificial well and clean the wellbore;

[0015] 2) Use a 700 cement truck to inject the sol treatment agent at a concentration of 8% to 10% (weight percentage) and an injection speed of 0.5 to 1m 3 / min, operation pressure ≤20MPa, treatment radius 3-4m, dissolving the displacement agent in the near-wellbore area;

[0016] 3) After the well is soaked for 10 hours, water injection is resumed and the reinjected water is used for displacement and isolation to further increase the swept volume of the sol treatment agent;

[0017] 4) Use a 700 cement truck to inject oil displacement agent and acidic plugging agent at an injection speed of 0.5 to 1m 3 / min, construction pressure ≤20MPa, treatment radius 2~3m, dissolve other organic and inorganic blockages;

[0018] 5) Displace the plugging agent in the wellbore into the formation;

[0019] 6) Resume injection after shutting down the well for 4-8 hours.

[0020] Furthermore, the oil displacing agent in step 4) is mixed benzene.

[0021] Furthermore, the acidic blocking agent in step 4) is mud acid.

[0022] The beneficial effects of the present invention compared with the prior art are:

[0023] The present invention comprises the steps of uniformly mixing sodium persulfate, ferrous sulfate, nonylphenol polyoxyethylene ether, imidazoline quaternary ammonium salt, fluorocarbon surfactant, ammonium chloride, and methanesulfonic acid, and then preparing the mixture at a specific mass concentration to produce a sol treatment agent. The sol treatment agent is suitable for unblocking polymer injection wells where the injection pressure is high due to gel blockage and the geological injection requirements cannot be met. The sol treatment agent is used as the main agent in combination with an oil displacement agent and an acidic unblocking agent, resulting in significant effects, restoring the normal injection capacity of the well and improving the water injection efficiency of the block.

[0024] The technical solution of this invention was tested in five wells at the Haiwaihe Oilfield, reducing the average injection pressure per well by 5.8 MPa and injecting a cumulative 43,000 cubic meters of fluid. The solution remained effective for an average of 227 days, with one well experiencing its effective period. This provided technical support for the on-site unblocking of injection wells in the Haiwaihe Oilfield. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a construction flow chart.

[0026] Figure 2 This is a test chart of the sol performance of the sol treatment agent.

[0027] Figure 3 This is the blockage removal construction curve diagram A of Hai 8-14 well.

[0028] Figure 4 This is the blockage removal construction curve diagram B of Hai 8-14 well.

[0029] Figure 5 This is the production curve of Hai 8-14 well. DETAILED DESCRIPTION

[0030] The present invention is described in detail below by specific examples, but the scope of protection of the present invention is not limited. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0031] Example 1

[0032] Well Hai 8-14 is a water injection well in Hai 1 block of Haihaihe Oilfield. It was used for water injection from 2012 to 2017 and injected 47,000 cubic meters of weak gel. In November 2021, the injection was stopped due to failure to inject water. The injection pressure was 12 MPa and the injection was 50m3. 3 , actual injection 0m 3 Due to the long flooding time and large injection volume, gel blockage and inorganic blockage such as clay particles occurred in the near-wellbore area. The well section has a depth of 43.9m / 17 layers, with an average porosity of 17.6% and a permeability of 429mD.

[0033] Preparation of the sol treatment agent: At room temperature, add 5% sodium persulfate and 3% ferrous sulfate to water and stir until evenly combined. Then, add 0.08% nonylphenol polyoxyethylene ether, 0.4% imidazoline quaternary ammonium salt, 0.05% fluorocarbon surfactant, 0.5% ammonium chloride, and 0.05% methanesulfonic acid in this order and stir until evenly combined. Percentages are by weight.

[0034] To test the agent's performance, the gel was placed in 5%, 8%, and 10% by weight sol treatment agent solutions and allowed to stand at a constant temperature of 60°C to observe its dissolution rate. The experimental results showed that the 5% concentration solution (by weight) had a poor sol effect, while the 8% to 10% concentration solution had a better sol effect (by weight), completely dissolving the gel in 6-8 hours, which was sufficient for on-site use.

[0035] The specific steps for using sol treatment agent to remove blockage are as follows:

[0036] (1) Use a 700 cement truck to inject water 80m 3 , cleaning the wellbore, construction pressure 11.5MPa.

[0037] (2) Sol treatment agent slug: According to the basic data of the well, the treatment radius is calculated as 3m (Q = πr 2 Hφ), use unblocking agent 220m 3 It contains two slugs. Slug 1 uses 5t of sol treatment agent at a concentration of 10% (weight percentage) to prepare 50t of gelling plugging agent, with an application pressure of 0-11MPa. Slug 2 uses 13.6t of sol treatment agent at a concentration of 8% (weight percentage) to prepare 170t of gelling plugging agent, with an application pressure of 11-11.5-9.5MPa.

[0038] (3) The well was soaked for 12 hours and the main line was water-injected for 20 days to push the sol treatment agent deep into the formation and subsequently isolate it from the slug.

[0039] (4) Use a 700 cement truck to inject 10 tons of mixed benzene at a construction pressure of 15 MPa; and inject 80 tons of soil acid at a construction pressure of 15-7 MPa.

[0040] (5) After 4 hours of reaction, water injection into the main line was resumed.

[0041] Effect: After the measures were effective, the injection pressure was 12↘9.2MPa, and the daily injection was 50m 3 , actual injection 47.3m 3 Under the mainline water injection pressure, the geological injection is basically satisfied. The well has been normally injected with water for 353 days, with a cumulative injection of 16,857m 3 , is still valid, pressure 9.5MPa, daily injection 50m 3 .

[0042] Performance test of the sol treatment agent prepared in Example 1 of the present invention:

[0043] 0.25% anionic polyacrylamide (weight percentage) and 0.15% organic chromium crosslinking agent (weight percentage) were added to the re-injection water of the Overseas River, stirred for 2 hours, and then kept at 60°C for 7 days to prepare an organic chromium gel. Sixteen gel samples were added with 5% to 12% sol treatment agent (weight percentage) at different concentrations, kept at 60°C, and the sol effect of each sample was observed. The results are shown in Table 1:

[0044] Table 1 Sol properties of sol treating agent

[0045]

[0046] The results show that when the concentration is higher than 8% (weight percentage), it has a better sol effect and can completely dissolve the gel within 8 hours; when the concentration is lower than 8% (weight percentage), the sol time is significantly extended, and the sol time can reach up to 16 hours; considering the economic efficiency of the measure, the concentration can be controlled at 8% to 10% (weight percentage), and the sol rate (60℃, 8h) ≥99%.

[0047] In order to detect the corrosion rate of the sol treatment agent on the pipe column, an N80 steel sheet with a size of 50mm×10mm×3mm was used and suspended in the sol treatment agent solution. The corrosion time was 4h and the temperature was 60℃. The corrosion conditions are shown in Table 2 below.

[0048] Table 2 Corrosion performance test of sol treatment agent

[0049]

[0050] The experimental results show that the corrosion rate increases with the increase of concentration. The corrosion rate of N80 steel sheet at a concentration of 10% (weight percentage) is only 0.5g / m 2 h, the maximum corrosion rate is 3.5g / m 2 h, below the standard (less than 8g / m 2 ·h).

[0051] Application Examples

[0052] The sol treatment agent and plugging removal application method of the present invention were tested in five wells at the Haiwaihe Oilfield. The results are shown in Table 3. The average injection pressure per well was reduced by 5.8 MPa, with a cumulative injection volume of 43,000 cubic meters. The average effective period was 227 days, and the effective period for one well remained unexpired. This provides technical support for on-site plugging removal in injection wells at the Haiwaihe Oilfield.

[0053] Well Hai 25 is a water injection well in Hai 1 block of Haihaihe Oilfield. It was subjected to profile adjustment and flooding from 2012 to 2019, and 81,200 cubic meters of weak gel were injected. In November 2019, the underfilling started. The average injection pressure in the 30 days before the plugging was unblocked was 12.4 MPa, and the injection was 60m3. 3 , actual injection 18.9m 3 The well section has a depth of 35.9m / 10 layers, an average porosity of 20.1% and a permeability of 22.5mD.

[0054] Preparation of the sol treatment agent: At room temperature, add 5% sodium persulfate and 3% ferrous sulfate to water and stir until evenly combined. Then, add 0.06% nonylphenol polyoxyethylene ether, 0.3% imidazoline quaternary ammonium salt, 0.04% fluorocarbon surfactant, 0.6% ammonium chloride, and 0.08% methanesulfonic acid in this order and stir until evenly combined. Percentages are by weight.

[0055] Well Hai 8-14 is a water injection well in Hai 1 block of Haihaihe Oilfield. It was used for water injection from 2012 to 2017 and injected 47,000 cubic meters of weak gel. In November 2021, the injection was stopped due to failure to inject water. The injection pressure was 12 MPa and the injection was 50m3. 3 , actual injection 0m 3 The well section is 43.9m / 17 layers, with an average porosity of 17.6% and a permeability of 429mD.

[0056] Preparation of the sol treatment agent: At room temperature, add 5% sodium persulfate and 3% ferrous sulfate to water and stir until evenly combined. Then, add 0.08% nonylphenol polyoxyethylene ether, 0.4% imidazoline quaternary ammonium salt, 0.05% fluorocarbon surfactant, 0.5% ammonium chloride, and 0.05% methanesulfonic acid in this order and stir until evenly combined. Percentages are by weight.

[0057] Well Hai 4-17 is a water injection well in Hai 1 block of Haiwaihe Oilfield. It was subjected to profile adjustment and flooding from 2011 to 2017, and 78,000 cubic meters of weak gel were injected. In September 2019, the underfilling started. The average injection pressure in the 30 days before the plugging was unblocked was 12.1 MPa, and the injection was 60m3. 3 , actual injection 10.3m 3 The well section has a depth of 16.5m / 10 layers, an average porosity of 22%, and a permeability of 690mD.

[0058] Preparation of the sol treatment agent: At room temperature, add 4% sodium persulfate and 2% ferrous sulfate to water and stir until evenly combined. Then, add 0.06% nonylphenol polyoxyethylene ether, 0.3% imidazoline quaternary ammonium salt, 0.04% fluorocarbon surfactant, 0.5% ammonium chloride, and 0.06% methanesulfonic acid in this order and stir until evenly combined. Percentages are by weight.

[0059] Well Hai 9-9 is a water injection well in Haiwaihe Oilfield. It was used for water injection from 2013 to 2017 and injected 34,000 cubic meters of weak gel. In June 2021, the well was shut down due to failure to inject water. The injection pressure was 14.1 MPa and the injection pressure was 50m3. 3 , actual injection 0m 3 The well section is 10.7m / 6 layers, with an average porosity of 29.6% and a permeability of 2527mD.

[0060] Preparation of the sol treatment agent: At room temperature, add 3% sodium persulfate and 2% ferrous sulfate to water and stir until evenly combined. Then, add 0.05% nonylphenol polyoxyethylene ether, 0.3% imidazoline quaternary ammonium salt, 0.03% fluorocarbon surfactant, 0.5% ammonium chloride, and 0.05% methanesulfonic acid in this order and stir until evenly combined. Percentages are by weight.

[0061] Well Hai 6-14 is a water injection well in Hai 1 block of Haihaihe Oilfield. It was subjected to profile adjustment and flooding from 2012 to 2019, and 101,000 cubic meters of weak gel was injected. In June 2022, the short injection was started. The average injection pressure in the first 30 days before the plugging was unblocked was 12 MPa, and the injection was 50m3. 3 , actual injection 14.3m 3 The well section is 18.9m / 7 layers, with an average porosity of 23.1% and a permeability of 886mD.

[0062] Preparation of the sol treatment agent: At room temperature, add 5% sodium persulfate and 3% ferrous sulfate to water and stir until uniform. Continue adding 0.01% nonylphenol polyoxyethylene ether, 0.5% imidazoline quaternary ammonium salt, 0.04% fluorocarbon surfactant, 0.6% ammonium chloride, and 0.08% methanesulfonic acid in this order and stir until uniform. Percentages are by weight.

[0063] Table 3 Statistics of blocking effect

[0064]

[0065] The present invention has achieved relatively obvious results in the implementation of the Overseas River Oilfield, providing certain technical support for the unblocking of injection wells in the Overseas River Oilfield and similar oilfields, and can be promoted and applied.

[0066] The above-described embodiments are only preferred embodiments of the present invention, and are not intended to be all feasible embodiments of the present invention. Any obvious modifications made by a person skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A sol treatment agent, characterized in that: The contents of each component are as follows in weight percentage: 3%~5% sodium persulfate, 2%~3% ferrous sulfate, 0.05~0.1% nonylphenol polyoxyethylene ether, 0.3~0.5% imidazoline quaternary ammonium salt, 0.03~0.05% fluorocarbon surfactant, 0.5~0.6% ammonium chloride, 0.05%~0.1% methanesulfonic acid, and the balance is water.

2. The method for preparing a sol treatment agent according to claim 1, wherein Sodium persulfate, ferrous sulfate, nonylphenol polyoxyethylene ether, imidazoline quaternary ammonium salt, fluorocarbon surfactant, ammonium chloride and methanesulfonic acid are added to water in sequence and stirred evenly to prepare a sol treating agent.

3. The sol treatment agent prepared by the preparation method of the sol treatment agent as claimed in claim 2 is used for unblocking polymer injection wells.

4. The sol treatment agent prepared by the preparation method of the sol treatment agent according to claim 2 is used for unblocking Well 25 in the Overseas River Oilfield, wherein: Well Hai-25 is a water injection well in the Hai-1 block of the Haiwaihe Oilfield. From 2012 to 2019, it implemented profile adjustment and flooding, injecting 81,200 cubic meters of weak gel. Shortage injection began in November 2019. Thirty days before plugging, the average injection pressure was 12.4 MPa, with 60 m³ of planned injection and 18.9 m³ of actual injection. The well has a 35.9 m / 10-layer section, an average porosity of 20.1%, and a permeability of 22.5 mD. Preparation of sol treatment agent: Under normal temperature conditions, add 5% sodium persulfate and 3% ferrous sulfate to water and stir evenly; then add 0.06% nonylphenol polyoxyethylene ether, 0.3% imidazoline quaternary ammonium salt, 0.04% fluorocarbon surfactant, 0.6% ammonium chloride, and 0.08% methanesulfonic acid in sequence and stir evenly; the percentages are weight percentages.

5. The sol treatment agent prepared by the preparation method of the sol treatment agent according to claim 2 is used for unblocking wells 8-14 in the Haiwaihe Oilfield, wherein: Well Hai 8-14 is a water injection well in the Hai 1 block of the Haiwaihe Oilfield. From 2012 to 2017, it implemented a profile adjustment and flooding operation, injecting 47,000 cubic meters of weak gel. In November 2021, injection was stopped due to failure to inject. The injection pressure was 12 MPa, the planned injection volume was 50 m³, and the actual injection volume was 0 m³. The well section is 43.9 m / 17 layers, with an average porosity of 17.6% and a permeability of 429 mD. Preparation of sol treatment agent: Under normal temperature conditions, add 5% sodium persulfate and 3% ferrous sulfate to water and stir evenly; then add 0.08% nonylphenol polyoxyethylene ether, 0.4% imidazoline quaternary ammonium salt, 0.05% fluorocarbon surfactant, 0.5% ammonium chloride, and 0.05% methanesulfonic acid in sequence and stir evenly; the percentages are weight percentages.

6. The sol treatment agent prepared by the preparation method of the sol treatment agent according to claim 2 is used for unblocking the well 4-17 of the Haiwaihe Oilfield, wherein: Well Hai 4-17 is a water injection well in the Hai 1 block of the Haiwaihe Oilfield. From 2011 to 2017, it implemented a profile adjustment and flooding operation, injecting 78,000 cubic meters of weak gel. Shortage injection began in September 2019. Thirty days before plugging, the average injection pressure was 12.1 MPa, with a planned injection of 60 m³ and an actual injection of 10.3 m³. The well has a well section of 16.5 m / 10 layers, an average porosity of 22%, and a permeability of 690 mD. Preparation of sol treatment agent: Under normal temperature conditions, add 4% sodium persulfate and 2% ferrous sulfate to water and stir evenly; then add 0.06% nonylphenol polyoxyethylene ether, 0.3% imidazoline quaternary ammonium salt, 0.04% fluorocarbon surfactant, 0.5% ammonium chloride, and 0.06% methanesulfonic acid in sequence and stir evenly; the percentages are weight percentages.

7. The sol treatment agent prepared by the preparation method of the sol treatment agent according to claim 2 is used for unblocking the 9-9 well of the Haiwaihe Oilfield, wherein: Well Hai 9-9 is a water injection well in the Hai 1 block of the Haiwaihe Oilfield. From 2013 to 2017, it was subjected to profile adjustment and flooding, injecting 34,000 cubic meters of weak gel. In June 2021, the well was shut down due to failure to inject water. The injection pressure was 14.1 MPa, the planned injection volume was 50 m³, and the actual injection volume was 0 m³. The well section has a 10.7 m / 6-layer interval, an average porosity of 29.6%, and a permeability of 2527 mD. Preparation of sol treatment agent: Under room temperature conditions, add 3% sodium persulfate and 2% ferrous sulfate to water and stir evenly; then add 0.05% nonylphenol polyoxyethylene ether, 0.3% imidazoline quaternary ammonium salt, 0.03% fluorocarbon surfactant, 0.5% ammonium chloride, and 0.05% methanesulfonic acid in sequence and stir evenly; the percentages are weight percentages.

8. The sol treatment agent prepared by the preparation method of the sol treatment agent according to claim 2 is used for unblocking well 6-14 in the Haiwaihe Oilfield, wherein: Well Hai 6-14 is a water injection well in the Hai 1 block of the Haiwaihe Oilfield. From 2012 to 2019, it implemented profile adjustment and flooding, injecting 101,000 cubic meters of weak gel. Shortage injection began in June 2022. In the 30 days before plugging, the average injection pressure was 12 MPa, with a planned injection of 50 m³ and an actual injection of 14.3 m³. The well section is 18.9 m / 7 layers, with an average porosity of 23.1% and a permeability of 886 mD. Preparation of sol treatment agent: Under normal temperature conditions, add 5% sodium persulfate and 3% ferrous sulfate to water and stir evenly; then add 0.01% nonylphenol polyoxyethylene ether, 0.5% imidazoline quaternary ammonium salt, 0.04% fluorocarbon surfactant, 0.6% ammonium chloride, and 0.08% methanesulfonic acid in sequence and stir evenly; the percentages are weight percentages.

9. The application of the sol treatment agent as claimed in claim 3 in unblocking polymer injection wells, characterized in that: The specific unblocking methods are: 1) Carry out positive flushing of the water injection well to the artificial well bottom and clean the wellbore; 2) Use a 700 cement truck to inject the sol treatment agent at a concentration of 8~10wt% and an injection speed of 0.5~1m 3 / min, operation pressure ≤20MPa, treatment radius 3~4m, dissolving the displacement agent in the near-wellbore area; 3) After the well is shut down for 10 hours, water injection is resumed and reinjected water is used for displacement and isolation to further increase the swept volume of the sol treatment agent; 4) Use a 700 cement truck to inject oil displacement agent and acid plugging agent at an injection speed of 0.5~1m 3 / min, construction pressure ≤20MPa, treatment radius 2~3m, dissolve other organic and inorganic blockages; 5) Displace the plugging agent in the wellbore into the formation; 6) Resume injection after shutting down the well for 4-8 hours.

10. The application of the sol treatment agent according to claim 9 in unblocking polymer injection wells, characterized in that: The oil displacement agent in step 4) is mixed benzene; the acidic plugging remover in step 4) is earth acid.

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