A high temperature resistant polymer composite plugging agent and its preparation method and application

Abstract

The present invention provides a high temperature resistant polymer composite plugging agent and a preparation method and application thereof, and relates to the field of oil production technology. The high temperature resistant polymer composite plugging agent comprises: a reactive polymer, a polymer monomer, polyethyleneimine, a cross-linking agent, an initiator, isocyanate-modified wollastonite and water; the polymer monomer comprises acrylamide, N-vinyl caprolactam and isoeugenol methyl ether. The plugging agent has good plugging effect and excellent high temperature resistance.

Description

Technical Field

[0001] The invention relates to the technical field of oil production, and in particular to a high-temperature resistant polymer composite plugging agent and a preparation method and application thereof. Background Art

[0002] Heavy oil accounts for a large proportion of my country's crude oil production and is an important part of oil resources. The most effective method for heavy oil production is to inject high-temperature and high-pressure steam to reduce the viscosity of heavy oil and increase the fluidity of crude oil, thereby improving the efficiency of heavy oil production. In the process of injecting high-temperature steam, due to the strong heterogeneity of heavy oil reservoirs, the density difference between steam and heavy oil, the excessive fluidity ratio, and the influence of factors such as formation sanding, the steam absorption profile is uneven, resulting in gravity overload gas channeling. Gas channeling will reduce the volume sweep coefficient, and the thermal effect of steam cannot be fully utilized, resulting in a significant decrease in the thermal recovery rate of heavy oil. In order to improve the recovery efficiency of heavy oil and prevent the occurrence of gas channeling, chemical plugging agents are often used to plug the gas channeling channels, block the gas channeling channels, and improve the utilization degree and recovery rate of heavy oil. However, the temperature of the steam injected during heavy oil production is as high as 200°C or even higher, so the temperature resistance of the plugging agent is required to be high.

[0003] At present, the main high temperature resistant plugging agents include inorganic solid particles, cement slurry, foam and polymer gel plugging agents. The plugging effect of the former is poor, while polymer gel plugging agents are a type of plugging agent with better comprehensive performance. Polymer gel plugging agents have good injection performance and certain high temperature resistance, but when the temperature exceeds 150°C, the plugging effect of the plugging agent will be greatly reduced or even lose its plugging ability. The temperature of steam injected during heavy oil production is as high as 200°C or even higher, so conventional polymer gel plugging agents cannot meet the needs. Therefore, it is necessary to develop plugging agents with higher temperature resistance. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a high-temperature resistant polymer composite plugging agent and a preparation method and application thereof. The plugging agent has good plugging effect and excellent high-temperature resistance.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, a high temperature resistant polymer composite plugging agent comprises the following raw materials by weight: 5-8 parts of reactive polymer, 40-55 parts of polymerization monomer, 8-15 parts of polyethyleneimine, 0.1-0.5 parts of cross-linking agent, 0.1-0.3 parts of initiator, 3-8 parts of isocyanate modified wollastonite, and 60-70 parts of water.

[0007] Preferably, the high temperature resistant polymer composite plugging agent comprises the following raw materials in parts by weight: 7 parts of reactive polymer, 52 parts of polymer monomer, 11 parts of polyethyleneimine, 0.3 parts of cross-linking agent, 0.2 parts of initiator, 6 parts of isocyanate-modified wollastonite, and 65 parts of water.

[0008] Furthermore, the polymerizable monomers comprise acrylamide, N-vinyl caprolactam and isoeugenol methyl ether in a mass ratio of 10:(1-2):(1-3); preferably, the mass ratio of acrylamide, N-vinyl caprolactam and isoeugenol methyl ether is 10:1.4:2.

[0009] Furthermore, the reactive polymer is anionic polyacrylamide, the molecular weight of the anionic polyacrylamide is 10 million to 30 million, and the degree of hydrolysis is 20% to 30%.

[0010] Preferably, the anionic polyacrylamide has a molecular weight of 22 million and a degree of hydrolysis of 25%.

[0011] Furthermore, the isocyanate-modified wollastonite is prepared by the following method:

[0012] Wollastonite is dispersed in 1-2 times the mass of a solvent, refluxed at 90-100°C for 1-2 hours, a catalyst is added, nitrogen is introduced, and then isocyanate is added to react. After the reaction is completed, centrifugal filtration is performed and drying is performed to obtain isocyanate-modified wollastonite.

[0013] Preferably, in the preparation process of isocyanate-modified wollastonite, the amount of isocyanate used is 10-20% of the mass of wollastonite, more preferably 17%.

[0014] Preferably, in the preparation process of isocyanate-modified wollastonite, the isocyanate is selected from at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and diphenylmethane diisocyanate.

[0015] Preferably, the solvent is at least one of toluene, petroleum ether and carbon tetrachloride; the catalyst is selected from dibutyltin dilaurate and / or stannous octoate, and the added amount is 0.5-2% of the mass of wollastonite.

[0016] As a further preferred embodiment, the isocyanate-modified wollastonite further comprises a modification treatment using sulfadimethoxine, and the modification treatment steps are as follows:

[0017] Disperse isocyanate-modified wollastonite in 1-3 times the mass of toluene, adjust the pH to 9-10, add sulfadimethoxine, heat to 50-60°C and react for 10-15h, filter, wash and dry after the reaction; the amount of sulfadimethoxine used is 5-10% of the mass of the isocyanate-modified wollastonite.

[0018] Further, the crosslinking agent is selected from at least one of p-vinylbenzene, N,N'-methylenebisacrylamide, triallylamine, N,N'-m-phenylene bismaleimide, pentaerythritol triacrylate, formaldehyde, glyoxal, succindialdehyde, glutaraldehyde, adipaldehyde, o-phthalaldehyde, nonanedialdehyde, suberaldehyde, and paraformaldehyde, and more preferably at least one of N,N'-methylenebisacrylamide, triallylamine, and N,N'-m-phenylene bismaleimide.

[0019] Furthermore, the initiator is selected from at least one of azo initiators, organic peroxide initiators, inorganic peroxide initiators, and redox initiators; preferably at least one of ammonium persulfate, potassium persulfate, sodium persulfate, and benzoyl peroxide.

[0020] In another aspect, the preparation method of the above-mentioned high temperature resistant polymer composite plugging agent comprises the following steps:

[0021] (1) Adding the polymerization monomer into water and adjusting the pH to alkaline to obtain solution A;

[0022] (2) cooling the solution A obtained in step (1), introducing nitrogen protection, adding polyethyleneimine, initiator, and cross-linking agent to react, and obtaining solution B;

[0023] (3) The solution B obtained in step (2) is heated, and a reactive polymer and isocyanate-modified wollastonite are added to continue the reaction. After the reaction is completed, the temperature is cooled to room temperature, dried, and crushed to obtain the product.

[0024] Furthermore, in step (1), adjusting the pH to alkaline refers to adjusting the pH to 7.5-8.5 with alkaline solution and / or acid solution; the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, and ammonia water; and the acid solution is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and citric acid.

[0025] Furthermore, in step (2), the cooling refers to cooling to 5-8°C.

[0026] Furthermore, in step (2), the reaction time is 1-2 hours.

[0027] Furthermore, in step (3), the heating refers to heating to 65-75°C.

[0028] Furthermore, in step (3), the reaction time is 2-5 hours.

[0029] As a further preferred embodiment, the present invention first ultrasonically treats the reactive polymer and the isocyanate-modified wollastonite and then adds them to solution B for reaction, so that the reactive polymer and the isocyanate-modified wollastonite are mixed more uniformly with other components in the plugging agent, so that the plugging agent material forms a more uniform cross-linked network structure, enhances the stability of the network structure, improves the plugging effect, and greatly increases the effective plugging time of the plugging agent material for crack pores. The ultrasonic treatment step is: first mix the reactive polymer and the isocyanate-modified wollastonite and add them to water for ultrasonic treatment, the ultrasonic treatment power is 200-300W, the time is 10-20min, the temperature is 50-60°C, dry, and then add them to solution B for reaction.

[0030] On the other hand, the above-mentioned high temperature resistant polymer composite plugging agent is used in heavy oil thermal recovery.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention provides a polymer composite plugging agent, which not only has good plugging effect and strong high temperature resistance, but is still effective in reservoir conditions above 200°C, and has good long-term stability, which greatly increases the effective plugging time of the plugging agent for fracture pores.

[0033] (2) In the present invention, acrylamide, N-vinyl caprolactam and isoeugenol methyl ether are used as polymerization monomers for polymerization to prepare the plugging agent. The introduction of isoeugenol methyl ether into the main chain of the polymer molecule can effectively improve the high temperature resistance of the plugging agent. The cooperation of isoeugenol methyl ether and acrylamide, as well as N-vinyl caprolactam and acrylamide can make the high temperature resistance of the plugging agent reach above 200°C, greatly improving the high temperature resistance of the plugging agent. In addition, the cooperation of the three components helps to form a more stable cross-linking structure, thereby improving the plugging effect and stability of the plugging agent.

[0034] (3) The addition of isocyanate-modified wollastonite to the plugging agent of the present invention ensures that the wollastonite has good compatibility with other polymer components in the plugging agent, which helps to improve the high temperature resistance of the plugging agent. The wollastonite is further modified with sulfamethazine and then added to the plugging agent. The sulfamethazine is grafted onto the wollastonite, which helps to improve the stability of the wollastonite in the plugging agent, improve the long-term stability of the plugging agent, and further help to further improve the high temperature resistance of the plugging agent. DETAILED DESCRIPTION

[0035] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is only an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the invention of the present invention based on the disclosed content, and they should also fall within the scope of the present invention.

[0036] The present invention is further described below by way of specific examples. Unless otherwise specified, the various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels.

[0037] Example 1

[0038] A high temperature resistant polymer composite plugging agent, comprising the following raw materials:

[0039] 8kg of reactive polymer, 40kg of polymerization monomer, 15kg of polyethyleneimine, 0.1kg of triallylamine, 0.1kg of potassium persulfate, 3kg of isocyanate-modified wollastonite, and 60kg of water; among which:

[0040] The reactive polymer is anionic polyacrylamide, with a molecular weight of 10 million and a degree of hydrolysis of 20%;

[0041] The polymerization monomers are acrylamide, N-vinyl caprolactam and isoeugenol methyl ether in a mass ratio of 10:1:1.

[0042] The above-mentioned high temperature resistant polymer composite plugging agent is prepared by the following method:

[0043] (1) Adding the polymerization monomer into water and adjusting the pH to 7.5 to obtain solution A;

[0044] (2) Cooling the solution A obtained in step (1) to 5°C, introducing nitrogen protection, adding polyethyleneimine, potassium persulfate and triallylamine, and reacting for 1 hour to obtain solution B;

[0045] (3) The temperature of solution B obtained in step (2) is raised to 60°C, anionic polyacrylamide and isocyanate-modified wollastonite are added, and the reaction is continued for 2 hours. After the reaction is completed, the temperature is cooled to room temperature, dried, and crushed to obtain the product.

[0046] In this embodiment, isocyanate-modified wollastonite is prepared by the following method:

[0047] Wollastonite was dispersed in 2 times the mass of toluene, refluxed at 90°C for 1 hour, 1% of stannous octoate by mass of the wollastonite was added, nitrogen was introduced, and then 10% of hexamethylene diisocyanate by mass of the wollastonite was added to react. After the reaction was completed, centrifugal filtration was performed and the isocyanate-modified wollastonite was obtained by drying.

[0048] Example 2

[0049] A high temperature resistant polymer composite plugging agent, comprising the following raw materials:

[0050] 7kg of reactive polymer, 52kg of polymerization monomer, 11kg of polyethyleneimine, 0.2kg of N,N'-methylenebisacrylamide, 0.3kg of benzoyl peroxide, 6kg of isocyanate-modified wollastonite, and 65kg of water; among which,

[0051] The reactive polymer is anionic polyacrylamide, with a molecular weight of 22 million and a degree of hydrolysis of 25%;

[0052] The polymerization monomers are acrylamide, N-vinyl caprolactam and isoeugenol methyl ether in a mass ratio of 10:1.4:2.

[0053] The above-mentioned high temperature resistant polymer composite plugging agent is prepared by the following method:

[0054] (1) Add the polymerization monomer to water and adjust the pH to 8 to obtain solution A;

[0055] (2) Cooling the solution A obtained in step (1) to 5°C, introducing nitrogen gas for protection, adding polyethyleneimine, benzoyl peroxide, and N,N'-methylenebisacrylamide, and reacting for 1 hour to obtain solution B;

[0056] (3) The temperature of solution B obtained in step (2) is raised to 70° C., anionic polyacrylamide and isocyanate-modified wollastonite are added, and the reaction is continued for 5 h. After the reaction is completed, the temperature is cooled to room temperature, dried, and crushed to obtain the product.

[0057] In this embodiment, isocyanate-modified wollastonite is prepared by the following method:

[0058] Wollastonite was dispersed in 2 times the mass of toluene, refluxed at 90°C for 2h, 1% of stannous octoate by mass of the wollastonite was added, nitrogen was introduced, and then 17% of diphenylmethane diisocyanate by mass of the wollastonite was added to react. After the reaction was completed, centrifugal filtration was performed and the isocyanate-modified wollastonite was obtained by drying.

[0059] Example 3

[0060] A high temperature resistant polymer composite plugging agent, comprising the following raw materials:

[0061] 5kg of reactive polymer, 55kg of polymerization monomer, 8kg of polyethyleneimine, 0.5kg of N,N'-m-phenylene bismaleimide, 0.3kg of ammonium persulfate, 8kg of isocyanate-modified wollastonite, and 70kg of water; among which:

[0062] The reactive polymer is anionic polyacrylamide, with a molecular weight of 30 million and a degree of hydrolysis of 30%;

[0063] The polymerization monomers are acrylamide, N-vinyl caprolactam and isoeugenol methyl ether in a mass ratio of 10:2:3.

[0064] The above-mentioned high temperature resistant polymer composite plugging agent is prepared by the following method:

[0065] (1) adding polymerization monomers (acrylamide, N-vinyl caprolactam and isoeugenol methyl ether in a mass ratio of 10:2:3) to water, and adjusting the pH to 8.5 to obtain solution A;

[0066] (2) Cooling the solution A obtained in step (1) to 8°C, introducing nitrogen protection, adding polyethyleneimine, ammonium persulfate, and N,N'-m-phenylene bismaleimide to react for 2 hours to obtain solution B;

[0067] (3) The temperature of solution B obtained in step (2) was raised to 75°C, 5 kg of anionic polyacrylamide and isocyanate-modified wollastonite were added, and the reaction was continued for 5 h. After the reaction was completed, the temperature was cooled to room temperature, dried, and crushed to obtain the product.

[0068] In this embodiment, isocyanate-modified wollastonite is prepared by the following method:

[0069] Wollastonite was dispersed in 2 times the mass of toluene, refluxed at 100°C for 2h, 1% of stannous octoate by mass of the wollastonite was added, nitrogen was introduced, and then 20% of dicyclohexylmethane diisocyanate by mass of the wollastonite was added to react. After the reaction, centrifugal filtration was performed and the mixture was dried to obtain isocyanate-modified wollastonite.

[0070] Example 4

[0071] The difference from Example 2 is that the isocyanate-modified wollastonite is replaced by an equal amount of sulfadimethoxine / isocyanate-modified wollastonite, and the sulfadimethoxine / isocyanate-modified wollastonite is prepared by the following method:

[0072] Disperse wollastonite in 2 times the mass of toluene, reflux at 90°C for 2h, add 1% of stannous octoate by mass of the wollastonite, pass nitrogen, then add 17% of diphenylmethane diisocyanate by mass of the wollastonite to react, centrifuge and filter after the reaction, and dry to obtain isocyanate-modified wollastonite; disperse the isocyanate-modified wollastonite in 3 times the mass of toluene, adjust the pH to 9, add 5% of sulfadimethoxine by mass of isocyanate-modified wollastonite, heat to 50°C to react for 10h, filter after the reaction, wash and dry to obtain.

[0073] Example 5

[0074] This embodiment provides another high temperature resistant polymer composite plugging agent, which is prepared by the following method:

[0075] (1) adding 52 kg of polymerization monomers (acrylamide, N-vinyl caprolactam and isoeugenol methyl ether in a mass ratio of 10:1.4:2) to 65 kg of water, and adjusting the pH to 8 to obtain solution A;

[0076] (2) Cooling the solution A obtained in step (1) to 5°C, introducing nitrogen protection, adding 11 kg of polyethyleneimine, 0.2 kg of benzoyl peroxide, and 0.3 kg of N,N'-methylenebisacrylamide, and reacting for 1 hour to obtain solution B;

[0077] (3) Add 7 kg of anionic polyacrylamide (molecular weight 22 million, degree of hydrolysis 25%) and 6 kg of isocyanate-modified wollastonite to 2 times the mass of water for ultrasonic treatment at a power of 300 W, a time of 20 min, a temperature of 50 ° C, and then dry;

[0078] (4) The temperature of solution B obtained in step (2) is raised to 70° C., and the anionic polyacrylamide and isocyanate-modified wollastonite treated in step (3) are added and the reaction is continued for 5 h. After the reaction is completed, the temperature is cooled to room temperature, dried, and crushed to obtain the product.

[0079] In this embodiment, the isocyanate-modified wollastonite is the same as that in Embodiment 2.

[0080] Example 6

[0081] The difference from Example 6 is that the power of the ultrasonic treatment in step (3) of this example is 100 W, the time is 20 min, and the temperature is 60°C.

[0082] Example 7

[0083] The difference from Example 6 is that the power of the ultrasonic treatment in step (3) of this example is 400 W, the time is 20 min, and the temperature is 40°C.

[0084] Comparative Example 1

[0085] The difference from Example 2 is that the polymerization monomers in this comparative example are acrylamide and N-vinyl caprolactam in a mass ratio of 10:1.4, and the total amount of the polymerization monomers remains unchanged.

[0086] Comparative Example 2

[0087] The difference from Example 2 is that the polymerization monomers in this comparative example are acrylamide and isoeugenol methyl ether in a mass ratio of 10:2, and the total amount of the polymerization monomers remains unchanged.

[0088] Comparative Example 3

[0089] The difference from Example 2 is that the polymerizable monomer in this comparative example is only acrylamide, and the total amount of the polymerizable monomer remains unchanged.

[0090] Comparative Example 4

[0091] The difference from Example 2 is that the isocyanate-modified wollastonite in this comparative example is replaced by an equal amount of wollastonite.

[0092] Comparative Example 5

[0093] The difference from Example 2 is that no isocyanate-modified wollastonite is added in this comparative example.

[0094] Test Example 1

[0095] The Darcy principle was applied to test its plugging performance. The test method is as follows: fill a simulated core (core diameter d = 25mm, length L = 200mm), and after vacuuming, inject water into the core at a flow rate of 2 ml / min (injection rate Q), and measure the core permeability before plugging (k0); then inject 1.0-1.5PV salt-resistant plugging agent into the core mold, plug the two ends of the core with wire plugs, put the core in a constant temperature box for a certain number of days, and inject water again until the pressure is stable, and obtain the core permeability after plugging (k), so as to calculate the plugging rate η, and the calculation formula is:

[0096]

[0097] The plugging rates of the high temperature resistant polymer composite plugging agents obtained in the above examples and comparative examples were tested after standing at a temperature of 150° C. for 60 days. The results are shown in Table 1 below.

[0098] Table 1

[0099]

[0100] As shown in the table, under the condition of standing at 150°C for 60 days, the plugging rates of the plugging agents of Examples 1-7 are all above 99%, with high plugging rates and good plugging effects. Compared with the plugging agents of Comparative Examples 1-3 containing only one or two polymerized monomers, the plugging agent of Example 2 has a higher plugging rate. It can be seen that the present invention uses acrylamide, N-vinyl caprolactam and isoeugenol methyl ether as polymerized monomers, and the three components cooperate with each other to effectively improve the plugging effect of the plugging agent. Compared with Comparative Examples 4 and 5 that do not contain isocyanate-modified wollastonite, the plugging rate of the plugging agent of Example 2 is higher. It can be seen that isocyanate-modified wollastonite helps to improve the compatibility of wollastonite with other components in the plugging agent, improves dispersibility, and improves the plugging effect of the plugging agent.

[0101] Test Example 2

[0102] The high temperature resistance is evaluated by the dehydration rate and plugging rate at different temperatures. The dehydration rate is determined as follows: the plugging agent is placed in a closed stainless steel reactor, placed in a constant temperature box for reaction, taken out of the constant temperature box at fixed intervals, and the mass of water removed from the gel is weighed on a balance. The ratio of this mass to the mass of the initial gelling liquid is the dehydration rate. The measured results are shown in Table 2 below.

[0103] Table 2

[0104]

[0105] As shown in the table, under the condition of standing at 150°C for 60 days, the dehydration rate of the plugging agent of Examples 1-7 is not higher than 3.0%, and under the condition of standing at 200°C for 60 days, the dehydration rate of the plugging agent of Examples 1-7 is not higher than 8.0%, and the plugging rate is still higher than 99%. This shows that the plugging agent prepared by the present invention can stably exist at 200°C and maintain a high plugging rate, and can effectively block the steam channel for a long time, which greatly improves the effective plugging time of the plugging agent for the crack pores.

[0106] Compared with the plugging agents in comparative examples 1-3 which contain only one or two polymerizable monomers, the dehydration rate of the plugging agent in Example 2 is significantly lower than that in comparative examples 1-3, and the plugging rate at high temperature is also higher than that in comparative examples 1-3. It can be seen that using acrylamide, N-vinyl caprolactam and isoeugenol methyl ether as polymerizable monomers, the three components work together to effectively improve the plugging effect of the plugging agent.

[0107] Compared with comparative examples 4 and 5 which do not contain isocyanate-modified wollastonite, the dehydration rate of the plugging agent in Example 2 is lower than that of comparative examples 4 and 5, and the plugging rate is higher than that of comparative examples 4 and 5. It can be seen that isocyanate-modified wollastonite helps to improve the compatibility of wollastonite with other components in the plugging agent, thereby exerting the role of wollastonite and improving the high temperature resistance of the plugging agent.

[0108] Test Example 3

[0109] The stability is evaluated by the change of apparent viscosity. The test method is as follows: add the plugging agent to water at a mass concentration of 0.5%, let it stand at room temperature for 2 hours, and then test it at 80°C and a shear rate of 7.34s -1 The apparent viscosity of the sample was measured under the following conditions as the initial viscosity, and then the apparent viscosity after long-term storage was measured. The results are shown in Table 3 below.

[0110] Table 3

[0111]

[0112] As shown in the table, the plugging agents of Examples 1-3 have a small change in apparent viscosity after 180 days, and have good long-term stability. Compared with Example 2, the isocyanate-modified wollastonite in the plugging agent of Example 4 is further modified, which helps to further improve the stability of the plugging agent, and the apparent viscosity change is reduced. During the preparation process of the plugging agent of Example 5, the reactive polymer and the isocyanate-modified wollastonite are ultrasonically treated, which helps to mix the two components with other ingredients of the plugging agent more evenly, forming a more stable cross-linked structure, thereby improving the stability of the plugging agent. Compared with the plugging agents of Comparative Examples 1-3 containing only one or two polymerized monomers, the apparent viscosity decrease of Comparative Examples 1-3 is significantly higher than that of Example 2, and the three polymerized monomers work together to effectively improve the stability of the plugging agent.

[0113] Compared with Example 2, the isocyanate-modified wollastonite in the plugging agent of Example 4 is further modified, and the decrease in apparent viscosity after long-term storage is less than that in Example 2; in Comparative Example 4, unmodified wollastonite is added, and the apparent viscosity of the plugging agent obtained increases after being placed for 60 days, while in Comparative Example 5, no wollastonite is added, and the apparent viscosity of the plugging agent obtained changes less within 120 days, and the decrease in apparent viscosity after being placed for 180 days is significantly higher than that in Example 2. It can be seen that the modification of wollastonite helps to improve the long-term stability of the plugging agent.

[0114] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A high temperature resistant polymer composite plugging agent, characterized in that: The invention comprises the following raw materials by weight: 5-8 parts of reactive polymer, 40-55 parts of polymer monomer, 8-15 parts of polyethyleneimine, 0.1-0.5 parts of crosslinking agent, 0.1-0.3 parts of initiator, 3-8 parts of isocyanate-modified wollastonite or isocyanate-modified wollastonite further modified by sulfadimethoxine, and 60-70 parts of water; wherein, The polymerization monomers include acrylamide, N-vinyl caprolactam and isoeugenol methyl ether in a mass ratio of 10:1-2:1-3; The reactive polymer is anionic polyacrylamide; The isocyanate-modified wollastonite is prepared by the following method: Disperse wollastonite in a solvent, reflux for 1-2 hours, add a catalyst, introduce nitrogen, then add isocyanate to react, centrifuge and filter after the reaction, and dry to obtain isocyanate-modified wollastonite; the amount of isocyanate used is 10-20% of the mass of wollastonite; The isocyanate-modified wollastonite further modified by sulfadimethoxine has the following modification steps: Disperse isocyanate-modified wollastonite in a solvent, adjust the pH to 9-10, add sulfadimethoxine to react, filter, wash and dry after the reaction is completed.

2. The high temperature resistant polymer composite plugging agent according to claim 1, characterized in that: The molecular weight of the anionic polyacrylamide is 10 million to 30 million, and the degree of hydrolysis is 20% to 30%.

3. The high temperature resistant polymer composite plugging agent according to claim 1, characterized in that: The mass ratio of acrylamide, N-vinyl caprolactam and isoeugenol methyl ether is 10:1.4:

2.

4. The high temperature resistant polymer composite plugging agent according to claim 1, characterized in that: The isocyanate is selected from at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and diphenylmethane diisocyanate.

5. The high temperature resistant polymer composite plugging agent according to claim 1, characterized in that: The dosage of sulfadimethoxine is 5-10% of the mass of the isocyanate-modified wollastonite.

6. The method for preparing the high temperature resistant polymer composite plugging agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Adding the polymerization monomer into water and adjusting the pH to alkaline to obtain solution A; (2) cooling the solution A obtained in step (1), introducing nitrogen protection, adding polyethyleneimine, initiator, and cross-linking agent to react, and obtaining solution B; (3) The solution B obtained in step (2) is heated, and a reactive polymer and isocyanate-modified wollastonite are added to continue the reaction. After the reaction is completed, the temperature is cooled to room temperature, dried, and crushed to obtain the product.

7. Use of the high temperature resistant polymer composite plugging agent according to any one of claims 1 to 5 in thermal recovery of heavy oil.

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