Degradable bio-based resin water shutoff agent suitable for low-temperature oil reservoirs and application thereof

Abstract

The application provides a degradable bio-based resin water shutoff agent suitable for low-temperature oil reservoirs and application thereof, and the degradable bio-based resin water shutoff agent comprises the following components: base fluid 82.4-90.6 parts, curing agent 5.6-12.0 parts, initiator 0.1-3 parts, and reinforcing agent 1.5-2.2 parts, wherein the base fluid is epoxidized sucrose soybean oil acid ester. The modified soybean oil in the degradable bio-based resin water shutoff agent contains a large number of epoxy groups, under the oil reservoir temperature environment of 50-120 DEG C, the epoxy groups are ring-opened under the action of the initiator, then are associated with the curing agent to form macromolecules with a network structure, the reinforcing agent with a rigid group is introduced to further improve the hardness of the resin network structure, and a volatile organic compound-free, high-performance, full-bio-based thermosetting resin is prepared. The degradable bio-based resin water shutoff agent has high strength, high dilution resistance and excellent long-term stability; under the condition of 80 DEG C, the compressive strength of the resin is greater than 60 MPa, and the mass retention rate after aging for 60 days is greater than 95 %.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical technology, specifically relating to a biodegradable bio-based resin water shut-off agent suitable for medium- and low-temperature oil reservoirs and its application. Background Technology

[0002] In recent years, with the deepening of development, the number of high water-cut oil wells in some oilfields has increased year by year, seriously affecting the production capacity of single wells, the water drive efficiency of well groups, and the long-term stable production of oilfields, resulting in a year-on-year decline in oil recovery rates. Furthermore, some older oil wells have experienced casing perforation or damage due to various reasons, leading to deterioration of well conditions. After casing damage, the hydration and expansion of clay particles in the formation increases oil flow resistance, leading to a decrease in oil phase permeability, causing production losses, and simultaneously causing an imbalance in the injection-production well network and a decline in production levels. Moreover, casing damage can cause damage to the pressure system, making dynamic monitoring data acquisition difficult, seriously affecting the normal production of oil and water wells. On the other hand, the number of horizontal wells in oilfields has increased year by year. Due to the anisotropy of permeability in horizontal wells, coupled with the influence of factors such as cementing quality and staged fracturing in horizontal sections, the water injection situation around horizontal wells is complex, with severe external flow outside the casing, resulting in severe water production in some horizontal wells. Therefore, effectively managing high water-cut wells, casing-damaged wells, and external sealing issues in horizontal wells is of great significance for stabilizing production in old oilfields and accelerating their secondary development.

[0003] Currently, commonly used plugging agents in oilfields mainly include inorganic cement plugging agents, silicate plugging agents, polymer gel plugging agents, and resin plugging agents. Cement-based plugging agents have high curing strength, but they suffer from poor injectability and penetration, and are prone to shrinkage after curing, affecting the plugging effect. Furthermore, when plugging oil reservoirs, they can easily block oil flow channels, and the plugging agents are difficult to degrade, causing permanent damage to the reservoir. Polymer gels are the most widely used in oilfield water shut-off, but ordinary polymer gel plugging agents have poor dilution resistance and poor long-term stability, resulting in low plugging efficiency. Conventional resin plugging agents, such as epoxy resin and phenolic resin, have high strength, are difficult to degrade, and have poor adaptability to field construction. For example, Chinese invention patent application number CN107699219A discloses a high-temperature resistant, high-strength resin gel system that has a good plugging effect on crossflow channels; however, resin gels are expensive, have poor selectivity, are difficult to degrade, and can easily cause permanent damage to the reservoir. Chinese invention patent application number CN 113355071 A discloses a biodegradable high-strength resin water-blocking agent, its preparation method, and its application. This biodegradable high-strength resin water-blocking agent is composed of the following raw materials in parts by weight: 79.2 to 88.6 parts of epoxy vegetable residue oil, 5.4 to 13.2 parts of curing agent, 0.8 to 1.8 parts of initiator, 4.2 to 4.8 parts of toughening agent, and 0.5 to 1.2 parts of reinforcing agent. The sum of the weight parts of the above components is 100 parts. However, this resin water-blocking agent is mainly used in oil and gas reservoirs with temperatures above 125°C. Under medium and low temperature (<120°C) reservoir conditions, the curing time is too long, and the strength after curing is relatively low.

[0004] Therefore, there is an urgent need to develop a water shut-off agent with advantages such as low price, high strength, biodegradability, and anti-dilution properties, to provide technical support for improving the oilfield recovery rate. Summary of the Invention

[0005] To address the shortcomings of existing resin plugging agents, the present invention aims to provide a biodegradable bio-based resin water plugging agent suitable for medium- and low-temperature oil reservoirs, which can be used to solve the plugging problems of high water-cut wells, casing-damaged wells, and external sealing of horizontal wells.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned biodegradable bio-based resin water-blocking agent suitable for medium- and low-temperature oil reservoirs;

[0007] The third objective of this invention is to provide the application of the above-mentioned biodegradable bio-based resin water-blocking agent suitable for medium- and low-temperature oil reservoirs, which is applicable to oil and gas reservoirs at temperatures of 50–120°C.

[0008] This invention is achieved through the following technical solution:

[0009] A biodegradable bio-based resin water shut-off agent suitable for medium- and low-temperature oil reservoirs, the composition of which is as follows by weight: base liquid 82.4-90.6 parts, curing agent 5.6-12.0 parts, initiator 0.1-3 parts, reinforcing agent 1.5-2.2 parts, the sum of the weight of the above components is 100 parts;

[0010] Preferably, the base liquid is an epoxidized sucrose soybean oleate, and the specific preparation steps are as follows: soybean oil and ethanol in a certain proportion are synthesized into soybean oleate under the catalysis of anhydrous potassium carbonate; soybean oleate and sucrose are synthesized into sucrose soybean oleate under the catalysis of hexadecyltrimethylammonium bromide; then, the crude product is obtained by epoxidation treatment with m-chloroperbenzoic acid (m-CPBA), and the product is purified by alkali washing and water washing to obtain epoxidized sucrose soybean oleate.

[0011] Preferably, the curing agent is one or more of maleic anhydride, 4-methyl-1,2-cyclohexanedicarboxylic anhydride, and trimellitic anhydride.

[0012] Preferably, the initiator is one or more of 2-methylimidazole, di-tert-butylperoxide, and azobisisobutyronitrile.

[0013] Preferably, the reinforcing agent is selected from one or more of isosorbide and dimethyl phthalate.

[0014] The preparation steps of the above-mentioned biodegradable bio-based resin water-blocking agent are as follows:

[0015] (1) Add the base liquid to a 150ml beaker, and then add the curing agent while stirring at a speed of 500r / min and stir until uniform;

[0016] (2) While stirring, add the initiator and reinforcing agent to the beaker in step (1) in proportion, and continue stirring at a stirring speed of 300 r / min for 1.5 h to prepare a gelling solution;

[0017] (3) Weigh 20g of the gelling solution and add it into a pressure-resistant bottle, then place it in an oil bath at 80℃ and react for 4 to 18 hours to obtain the above-mentioned biodegradable bio-based resin water-blocking agent.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0019] (1) The main raw material of this biodegradable bio-based resin water-blocking agent is bio-based oil, specifically soybean oil modified to obtain epoxidized sucrose soybean oleate, which is widely available, inexpensive, green, and environmentally friendly.

[0020] (2) The modified soybean oil (epoxidized sucrose soybean oleate) of this invention contains a large number of epoxy groups. In a high-temperature environment, the epoxy groups undergo ring-opening under the action of an initiator, and then associate with a curing agent to form a macromolecule with a network structure. The introduction of a reinforcing agent with rigid groups further improves the hardness of the resin network structure, thereby preparing a high-performance, fully bio-based thermosetting resin free of volatile organic compounds. This biodegradable bio-based resin water-blocking agent exhibits high strength, strong resistance to dilution, and excellent long-term stability; its compressive strength at 80℃ is greater than 60 MPa, and its mass retention rate after 60 days of aging is greater than 95%.

[0021] (3) The biodegradable bio-based resin plugging agent of the present invention is a liquid homogeneous system with low viscosity of the gelling liquid, which can enter tiny cracks and has excellent penetration performance, enabling long-distance plugging.

[0022] (4) The biodegradable bio-based resin water plugging agent of the present invention is mainly polymerized in the form of ester bond and ether bond. When placed in the resin degrading agent at a temperature of 80°C for 24 to 72 hours, the biodegradable bio-based resin water plugging agent can be completely degraded. The unblocking agent is a non-acid system. The solution after unblocking is similar to oil and water in nature and will not cause damage to the oil reservoir. Detailed Implementation

[0023] The implementation of the present invention will be described in detail below with reference to the embodiments. It should be understood that the preferred embodiments are for illustration and explanation of the present invention and are not intended to limit the present invention. At the same time, the advantages of the present invention will become clearer and easier to understand through examples.

[0024] It should be noted that the implementation conditions used in the examples can be further adjusted according to the specific experimental environment, and the implementation conditions not specified are usually those in conventional experiments. Unless otherwise specified, the preparation methods mentioned in this invention are all conventional methods; all raw materials mentioned in the following examples are obtained from publicly available commercial sources unless otherwise specified.

[0025] The present invention first provides a biodegradable bio-based resin water shut-off agent suitable for medium and low temperature oil reservoirs, which comprises the following components by weight: 82.4 to 90.6 parts of base liquid, 5.6 to 12.0 parts of curing agent, 0.1 to 3 parts of initiator, and 1.5 to 2.2 parts of reinforcing agent.

[0026] Preferably, the base liquid is epoxidized sucrose soybean oleate.

[0027] Preferably, the curing agent is one or more of maleic anhydride, 4-methyl-1,2-cyclohexanedicarboxylic anhydride, and trimellitic anhydride.

[0028] Preferably, the initiator is one or more of 2-methylimidazole, di-tert-butyl peroxide, and azobisisobutyronitrile.

[0029] Preferably, the reinforcing agent is one or more of isosorbide and dimethyl phthalate.

[0030] This biodegradable bio-based resin water-blocking agent has a compressive strength greater than 60 MPa at 80℃ and a mass retention rate greater than 95% after aging for 60 days.

[0031] In a preferred embodiment, the biodegradable bio-based resin water-blocking agent has the following composition at a temperature of 50-80°C: 82.4-90.6 parts base liquid, 5.6-12.0 parts curing agent, 1-3 parts initiator, and 1.5-2.2 parts reinforcing agent.

[0032] In a preferred embodiment, the biodegradable bio-based resin water-blocking agent has the following composition at a temperature of 80-120°C: 82.4-90.6 parts of base liquid, 5.6-12.0 parts of curing agent, 0.1-1 parts of initiator, and 1.5-2.2 parts of reinforcing agent.

[0033] This invention also provides a method for preparing a biodegradable bio-based resin water-blocking agent suitable for medium- and low-temperature oil reservoirs, comprising the following steps:

[0034] S1, add 82.4 to 90.6 parts by weight of the base liquid to the reaction vessel, and add 5.6 to 12.0 parts by weight of the curing agent while stirring at a speed of 400 to 600 r / min, and stir until uniform;

[0035] S2, while stirring, 0.8 to 1.5 parts by weight of initiator and 1.5 to 2.2 parts by weight of reinforcing agent are added to the reaction vessel in sequence. After stirring continuously at a speed of 250 to 300 r / min for 1.5 h, a gelling solution is obtained.

[0036] S3. Add the gelling solution into a pressure-resistant bottle, then place it in an oil bath at 50-120°C and react for 4-18 hours to obtain the biodegradable bio-based resin water-blocking agent.

[0037] The present invention further provides the application of the above-mentioned biodegradable bio-based resin water shut-off agent suitable for medium and low temperature reservoirs, which is suitable for reservoir temperature environments of 50 to 120°C.

[0038] The unblocking method of the biodegradable bio-based resin described in this invention involves directly injecting the degrading agent into the blocked site, after which the bio-based resin is completely degraded in 24–72 hours. Further, the degrading agent for the biodegradable bio-based resin is prepared from a mixed solution of tripotassium phosphate, benzyl alcohol, and water.

[0039] Preferably, the biodegradable bio-based resin degrading agent is composed of the following raw materials in parts by weight: 10 to 20 parts of tripotassium phosphate, 50 to 70 parts of benzyl alcohol, and 10 to 20 parts of water, the sum of the parts by weight of the above components being 100 parts.

[0040] The present invention will be further described below with reference to specific embodiments.

[0041] Example 1

[0042] This embodiment provides a method for preparing a biodegradable bio-based resin water-blocking agent. Specifically, 86.4g of epoxidized sucrose soybean oleate is added to a 150ml beaker. Under a stirring speed of 500r / min, 10.2g of maleic anhydride is slowly added to the beaker and stirred evenly. Then, 1.2g of 2-methylimidazole and 2.2g of isosorbide are added to the beaker in sequence. The stirring speed is adjusted to 300r / min and stirred continuously for 1.5h to obtain a resin gelling solution. 20g of the gelling solution is weighed and placed in a pressure-resistant bottle, and then placed in an oil bath at 80℃. After reacting for 8h, it is cured. The compressive strength of the resulting biodegradable bio-based resin water-blocking agent is 71.5MPa. Under the condition of 80℃, the cured water-blocking agent is placed in a resin degrading agent, and it can be completely degraded within 48 hours.

[0043] Example 2

[0044] This embodiment provides a method for preparing a biodegradable bio-based resin water-blocking agent. Specifically, 87.3g of epoxidized sucrose soybean oleate is added to a 150ml beaker. Under a stirring speed of 500r / min, 9.6g of maleic anhydride is slowly added to the beaker and stirred evenly. Then, 0.9g of di-tert-butyl peroxide and 2.2g of dimethyl phthalate are added to the beaker in sequence. The stirring speed is adjusted to 300r / min and stirred continuously for 1.5h to obtain a resin gelling solution. 20g of the gelling solution is weighed and placed in a pressure-resistant bottle, and then placed in an oil bath at 80℃. After reacting for 10h, it is cured. The compressive strength of the resulting resin water-blocking agent is 66.3MPa. Under the condition of 80℃, the cured water-blocking agent is placed in a resin degrading agent, and it can be completely degraded within 36 hours.

[0045] Example 3

[0046] This embodiment provides a method for preparing a biodegradable bio-based resin water-blocking agent. Specifically, 88.3g of epoxidized sucrose soybean oleate is added to a 150ml beaker. Under a stirring speed of 500r / min, 8.9g of 4-methyl-1,2-cyclohexanedicarboxylic anhydride is slowly added to the beaker and stirred evenly. Then, 0.6g of azobisisobutyronitrile and 2.2g of isosorbide are added to the beaker in sequence. The stirring speed is adjusted to 300r / min and stirred continuously for 1.5h to obtain a resin gelling solution. 20g of the gelling solution is weighed and placed in a pressure-resistant bottle, and then placed in an oil bath at 80℃. After reacting for 12h, it is cured. The compressive strength of the resulting resin water-blocking agent is 60.9MPa. Under the condition of 80℃, the cured water-blocking agent is placed in a resin degrading agent, and it can be completely degraded within 24 hours.

[0047] Implement column 4

[0048] This embodiment provides a method for preparing a biodegradable bio-based resin water-blocking agent. Specifically, 86.4g of epoxidized sucrose soybean oleate is added to a 150ml beaker. Under a stirring speed of 500r / min, 10.2g of 4-methyl-1,2-cyclohexanedicarboxylic anhydride is slowly added to the beaker and stirred until homogeneous. Then, 1.2g of 2-methylimidazole and 2.2g of dimethyl phthalate are added to the beaker sequentially. The stirring speed is adjusted to 300r / min and stirred continuously for 1.5h to obtain a resin gelling solution. 20g of the gelling solution is weighed and placed in a pressure-resistant bottle, then placed in an 80℃ oil bath. After reacting for 4h, it is cured. The resulting resin water-blocking agent has a compressive strength of 76.4MPa. Under the condition of 80℃, the cured water-blocking agent is placed in a resin degrading agent, and it can be completely degraded within 72 hours.

[0049] Example 5

[0050] This embodiment provides a method for preparing a biodegradable bio-based resin water-blocking agent. Specifically, 88.1g of epoxidized sucrose soybean oleate is added to a 150ml beaker. Under a stirring speed of 500r / min, 8.6g of trimellitic anhydride is slowly added to the beaker and stirred until homogeneous. Then, 1.5g of di-tert-butyl peroxide and 1.8g of isosorbide are added to the beaker sequentially. The stirring speed is adjusted to 300r / min and stirred continuously for 1.5h to obtain a resin gelling solution. 20g of the gelling solution is weighed and placed in a pressure-resistant bottle, then placed in an 80℃ oil bath. After reacting for 6h, the solution is cured. The compressive strength of the resulting resin water-blocking agent is 72.8MPa. Under 80℃ conditions, the cured water-blocking agent is placed in a resin degrading agent and can be completely degraded within 60 hours.

[0051] Example 6

[0052] This embodiment provides a method for preparing a biodegradable bio-based resin water-blocking agent. Specifically, 86.4g of epoxidized sucrose soybean oleate is added to a 150ml beaker. Under a stirring speed of 500r / min, 10.2g of trimellitic anhydride is slowly added to the beaker and stirred until homogeneous. Then, 1.2g of azobisisobutyronitrile and 2.2g of dimethyl phthalate are added to the beaker in sequence. The stirring speed is adjusted to 300r / min and stirred continuously for 1.5h to obtain a resin gelling solution. 20g of the gelling solution is weighed and placed in a pressure-resistant bottle, then placed in an 80℃ oil bath. After reacting for 18h, it is cured. The compressive strength of the resulting resin water-blocking agent is 66.1MPa. Under the condition of 80℃, the cured water-blocking agent is placed in a resin degrading agent, and it can be completely degraded within 48 hours.

[0053] Comparative Example 1

[0054] Weigh 20g of the gelling solution obtained in Example 1 and place it in a pressure-resistant bottle. Then place it in an oil bath at 50°C and let it react for 17 hours before curing. The resulting resin water-blocking agent has a compressive strength of 60.5MPa. Under the condition of 50°C, the cured water-blocking agent is placed in a resin degrading agent and can be completely degraded within 72 hours.

[0055] The other components, amounts, and reaction conditions of Comparative Example 1 were the same as those of Example 1.

[0056] Comparative Example 2

[0057] Weigh 20g of the gelling solution obtained in Example 1 and place it in a pressure-resistant bottle. Then place it in an oil bath at 120°C and let it react for 4 hours before curing. The resulting resin water-blocking agent has a compressive strength of 78.5MPa. Under the condition of 120°C, the cured water-blocking agent is placed in a resin degrading agent and can be completely degraded within 24 hours.

[0058] The other components, amounts, and reaction conditions in this comparative example are the same as in Example 1.

[0059] The following basic performance tests were conducted on the resin plugging agent samples prepared in the above embodiments:

[0060] Taking the biodegradable bio-based resin water-blocking agents obtained in Examples 1-6 and Comparative Examples 1-2 as examples, the curing time, initial compressive strength, final compressive strength, mass retention rate after 60 days of aging, and degradation performance of the water-blocking agents were investigated. The results are detailed in Tables 1 and 2:

[0061] Table 1 shows the basic properties of the biodegradable bio-based resin plugging agents obtained in Examples 1-6.

[0062]

[0063] Table 2 shows the basic properties of the water-blocking agents described in Comparative Examples 1-2.

[0064]

[0065] According to Tables 1 and 2, the curing time of the biodegradable bio-based resin plugging agent is controllable from 4 to 18 hours, the compressive strength is greater than 60 MPa, and the mass retention rate of the resin plugging agent after 60 days of aging is greater than 96%, still exhibiting good plugging performance. The degrading agent matched with the biodegradable bio-based resin plugging agent can ensure that the plugging agent is completely degraded within 72 hours.

[0066] The following are performance test results of the biodegradable bio-based resin water-blocking agent described in the above embodiments of the present invention:

[0067] 1. Degradation performance

[0068] Weigh 20g of the gelling solution obtained in Example 2 and place it in a pressure-resistant bottle. Then place it in an oil bath at 80°C and let it react for 10 hours before curing. The resulting resin water-blocking agent has a compressive strength of 66.3MPa. At 80°C, the water-blocking agent and the degradation agent are added to the pressure-resistant bottle at a mass ratio of 1:2. The mass retention rate of the water-blocking agent is tested every 6 hours. The results are shown in Table 3. The bio-based resin water-blocking agent can be completely degraded within 36 hours.

[0069] Table 3. Mass Retention Rate of Biodegradable Bio-based Resin Plugging Agent

[0070] Test time / h 0 6 12 18 24 30 36 Quality retention rate / % 100 93.6 85.2 69.8 51.6 32.3 0

[0071] 2. Sealing performance

[0072] Taking the gelling solutions prepared in Examples 3 and 4 as examples, the sealing ability of the water-blocking agent for cracks was investigated. The specific experimental steps were as follows: (1) Using artificial sandstone crack cores (core size was...) (2) Simulate the core holder displacement device and the water injection rate at saturation is 1 mL / min. After the pressure stabilizes, calculate the original permeability k0 and pore volume; (3) Inject 0.3 PV of the gelling solution in Example 3 and Example 4 and age it in an oven at 80℃ for 1 day and 60 days; (4) Set the water injection rate to 1 mL / min. After the pressure stabilizes, measure the permeability k1 after plugging. Calculate the core plugging rate E after injecting the oleogel solution using the formula E=(k0-k1) / k0×100%. The experimental results are shown in Table 4.

[0073] Table 4. Blocking efficiency of different water-blocking agent systems

[0074]

[0075] After aging for 60 days following the sealing of the fractured rock core with the water-blocking agent, the sealing rates of the biodegradable bio-based resin water-blocking agent formulations in Examples 3 and 4 were both higher than 99%, indicating that the water-blocking agent not only has excellent sealing properties but also good thermal stability.

[0076] 3. Long-term thermal stability

[0077] Using the biodegradable bio-based resin water-blocking agent prepared in Example 2 as the research object, the dilution resistance and long-term stability of the biodegradable bio-based resin water-blocking agent under formation conditions were investigated. The specific experimental steps are as follows: A gel solution was prepared according to the formula, and the gel solution was placed in a pressure-resistant bottle containing simulated water to undergo a cross-linking reaction. Then, the change in the mass retention rate of the resin water-blocking agent at different aging times (1 day, 30 days, and 60 days) was measured at 80°C, i.e., the ratio of the remaining resin water-blocking agent mass to the initial resin water-blocking agent mass. The experimental results showed that the mass retention rate of the resin water-blocking agent was 100% at 1 day, 98.5% at 30 days, and 95.4% at 60 days. This indicates that the biodegradable bio-based resin water-blocking agent has strong dilution resistance and excellent long-term thermal stability.

[0078] The above embodiments effectively demonstrate that the present invention provides a biodegradable bio-based resin plugging agent, which has advantages such as high strength, biodegradability, excellent plugging performance, deep penetration, strong anti-dilution performance, and excellent long-term stability, and can effectively solve the plugging problem of oil wells in oil fields.

Claims

1. A degradable bio-based resin water shutoff agent suitable for use in low to medium temperature reservoirs, characterized in that, By weight parts, including the following composition: base fluid 82.4~90.6 parts, curing agent 5.6~12.0 parts, initiator 0.1~3 parts, reinforcing agent 1.5 parts~2.2 parts; The base fluid is epoxidized sucrose soyate, and its synthesis method is: A certain proportion of soybean oil and ethanol are synthesized into soyate under the catalysis of anhydrous sodium carbonate; sucrose soyate is synthesized from soyate and sucrose under the catalysis of cetyltrimethylammonium bromide; and the crude product is obtained by epoxidation treatment with meta-chloroperbenzoic acid, and the product is purified by alkali washing and water washing to obtain epoxidized sucrose soyate; The curing agent is one or more of maleic anhydride, 4-methyl-1,2-cyclohexane dicarboxylic anhydride and trimellitic anhydride; The reinforcing agent is one or more of isosorbide and dimethyl phthalate; The amount of initiator is 1~3 parts at a temperature of 50~80℃; the amount of initiator is 0.1~1 part at a temperature of 80~120℃; The compressive strength of the degradable bio-based resin water plugging agent at 80℃ is greater than 60MPa, and the mass retention rate after aging for 60d is greater than 95%.

2. The biodegradable bio-based resin water shutoff agent suitable for use in low to moderate temperature reservoirs of claim 1, wherein: The initiator is one or more of 2-methylimidazole, di-t-butyl peroxide and azobisdimethyl isobutyronitrile.

3. The biodegradable bio-based resin water shutoff agent suitable for use in low to moderate temperature reservoirs of claim 1, wherein: The plugging method of the degradable bio-based resin water plugging agent is to directly inject the degrading agent into the plugging position, and the degradable bio-based resin water plugging agent is completely degraded after 24~72h.

4. The biodegradable bio-based resin water shutoff agent suitable for use in low to moderate temperature reservoirs of claim 3, wherein: The degrading agent is composed of the following raw materials by weight parts: 10~20 parts of potassium phosphate, 50~70 parts of benzyl alcohol and 10~20 parts of water.

5. A method for preparing the degradable bio-based resin water shutoff agent suitable for low-temperature reservoirs according to any one of claims 1-4, characterized in that, The method comprises the following steps: S1, 82.4~90.6 parts by weight of base fluid are added to the reaction container, 5.6~12.0 parts by weight of curing agent are added under the condition of stirring speed 400~600r / min, and stirring is uniform; S2, 0.1~3 parts by weight of initiator and 1.5~2.2 parts by weight of reinforcing agent are added to the reaction container while stirring, and stirring is continued at a speed of 250~300r / min for 1.5h to obtain a gel solution; S3, the gel solution is added to a pressure-resistant bottle, and then placed in an oil bath pot at 50~120℃, and reacted for 4~18h to obtain the degradable bio-based resin water plugging agent.

6. The use of the degradable bio-based resin water shutoff agent for low to medium temperature reservoirs according to any one of claims 1-4 or the degradable bio-based resin water shutoff agent prepared by the method of claim 5, characterized in that: The degradable bio-based resin water plugging agent is suitable for use in medium-low temperature reservoirs with a temperature range of 50~120℃.

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