Preparation method of high-temperature-resistant crosslinking agent, high-temperature-resistant crosslinking agent, oil field plugging agent, preparation method and application thereof

Abstract

The present application relates to a kind of preparation method of high-temperature resistant crosslinking agent and high-temperature resistant crosslinking agent, oilfield plugging agent and its preparation method and application.The high-temperature resistant crosslinking agent of the present application is with phenolic modified lignin instead of part phenolic substance, and aldehyde, organic bentonite is reacted to obtain phenolic aldehyde resin crosslinking agent.The high-temperature resistant crosslinking agent has higher decomposition temperature and hydroxymethyl content, lower free aldehyde content;It can be respectively with at least one of a variety of natural or synthetic polymers, crosslinking forms three-dimensional network structure, and is prepared into oilfield plugging agent, and is suitable for efficient development of different oil reservoirs.The present application improves the plugging strength, toughness, plugging efficiency and effective period of plugging and adjusting system by modifying crosslinking agent, meets the performance and economy requirements of field construction, and has higher practicality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil field chemicals, further relates to a preparation method of a high-temperature-resistant crosslinking agent, the high-temperature-resistant crosslinking agent, an oil field plugging agent, a preparation method and application thereof. BACKGROUND

[0002] Profile control refers to the operation of plugging high permeability layers from the injection well, which can adjust the water absorption profile of the injection interval. Water plugging refers to the operation of plugging high permeability layers from the oil well, which can reduce the water production of the oil well. After the plugging agent is solidified or expanded, the permeability of the high permeability layer is reduced, and the oil displacement effect of the injected water in the low permeability layer is improved. This process is called injection well profile control. Plugging and profile control technology is an effective means to improve the heterogeneity of the reservoir and achieve balanced displacement and stable production of the oil field under low oil prices. Existing plugging and profile control agents can be roughly divided into several categories, such as gel, gel, precipitation, particle, microsphere, foam and microorganism. Among them, the gel system is the most widely used and applied plugging agent in the current domestic and foreign plugging and profile control technology. The system is a space network structure formed by taking polymer as the main agent and Cr 3+ , Al 3+ , phenolic resin and the like as crosslinking agents. The Cr 3+ gel is a plugging and profile control agent formed by crosslinking reaction of polyacrylamide and polynuclear hydroxyl bridged chromium ions, which has the characteristics of adjustable freezing time, controllable strength and ability to plug different distances from the wellbore.

[0003] However, with higher requirements for the performance of oil field chemicals in the process of oil field field application, the existing plugging and profile control system has the disadvantages of poor temperature resistance, insufficient gel strength and toughness, and more importantly, the environmental protection problem of pollution of high-priced metal ions such as chromium crosslinking agent in application. The traditional Cr 3+ / HPAM system has been difficult to gradually meet the requirements, and the performance needs to be improved. Therefore, it is of great significance for the sustainable development of plugging and profile control technology to develop a crosslinking agent system with low cost, excellent product performance and meeting the requirements of temperature resistance. SUMMARY

[0004] In order to solve the problems in the prior art, the present application provides a preparation method of an oil field high-temperature-resistant crosslinking agent, the high-temperature-resistant crosslinking agent and application. The high-temperature-resistant crosslinking agent has a high decomposition temperature and a low free formaldehyde content. It can be crosslinked with at least one of a variety of natural or synthetic polymers to form a three-dimensional network structure, and can be controlled to gel in a wide temperature range (90-350℃), which is suitable for efficient development of different oil reservoirs. Through modification of the crosslinking agent, the plugging strength, toughness, plugging efficiency and effective period of the plugging and profile control system are significantly improved, which meets the performance and economic requirements of field construction, and has high practicability.

[0005] One of the purposes of the present application is to provide a preparation method of a high-temperature-resistant crosslinking agent, comprising the following steps:

[0006] (1) After contacting reaction of lignin and phenol in an alkaline catalyst solution, post-treatment is performed to obtain phenolated lignin;

[0007] (2) After pre-mixing of the phenolated lignin, phenol, aldehyde, polycondensation catalyst, organic bentonite and water, heating reaction is performed; after the reaction is completed, distillation and concentration are performed to obtain the high-temperature-resistant crosslinking agent.

[0008] The post-treatment method of the phenolated lignin in the present application is a conventional treatment method, such as cooling, or the pH can be further adjusted to precipitate the phenolated lignin.

[0009] In the present application, the lignin, phenol, alkaline catalyst, aldehyde, polycondensation catalyst and organic bentonite can be commercially available.

[0010] Preferably,

[0011] In step (1),

[0012] The lignin is selected from at least one of alkali lignin, enzymatic hydrolysis lignin, chlorinated lignin, steam explosion lignin or sulfur lignin; and / or

[0013] The phenol is selected from at least one of phenol, p-dihydroxybenzene, m-dihydroxybenzene or o-dihydroxybenzene; more preferably m-dihydroxybenzene; and / or

[0014] The alkaline catalyst in the alkaline catalyst solution is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate or ammonia; more preferably potassium hydroxide.

[0015] Preferably,

[0016] In step (1), the reaction system of the contacting reaction,

[0017] The concentration of the lignin is 20-35wt%;

[0018] The mass ratio of the phenol to the lignin is 0.2-0.4:1;

[0019] The concentration of the alkaline catalyst is 2-10wt%; preferably 2-8%;

[0020] In the present application, the conditions of the phenolization contacting reaction in step (1) are not particularly limited, and the phenolization modification of lignin can be achieved. The inventors found in the research that the phenolated lignin obtained under the phenolization conditions of a temperature of 88-92℃ and a time of 1-1.5h can achieve better results when used in the high-temperature-resistant crosslinking agent.

[0021] Preferably,

[0022] In step (2),

[0023] The phenol is selected from at least one of phenol, p-dihydroxybenzene, m-dihydroxybenzene or o-dihydroxybenzene; and / or

[0024] The aldehyde is selected from at least one of formaldehyde, acetaldehyde or furfural; and / or

[0025] The polycondensation catalyst is selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate or ammonia water;

[0026] In the present application, the organic bentonite is the commonly used organic bentonite, and is preferably selected from at least one of organic bentonite with intercalation agent being octadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide and tetradecyl trimethyl ammonium chloride.

[0027] Preferably,

[0028] In step (2),

[0029] The mass ratio of the phenolized lignin, phenol and aldehyde is (0.05-0.15):(0.2-0.5):1;

[0030] In the reaction system,

[0031] The concentration of the aldehyde is 4.5-9wt%; preferably 5-8%;

[0032] The concentration of the polycondensation catalyst is 0.5-1wt%;

[0033] The concentration of the organic bentonite is 0.5-2.5wt%; preferably 0.5-2%, more preferably 1.1-1.6wt%;

[0034] The stirring speed of the premixing is 150-300rpm;

[0035] In the present application, the reaction conditions of step (2) are not particularly limited, and the preparation of the high-temperature resistant crosslinking agent can be achieved. The inventors found in the research that the high-temperature resistant crosslinking agent obtained under the reaction conditions of temperature 78-82℃ and time 15-45min can achieve better effect when used in oil field plugging agent.

[0036] Preferably,

[0037] The temperature of the heating reaction is 78-82℃; and the time is 15-45min;

[0038] The stirring speed during the heating reaction is 500-800rpm;

[0039] The distillation is reduced pressure distillation, and the distillation is to a solid content of ≥ 40%.

[0040] The second object of the present application is to provide a high-temperature-resistant crosslinking agent prepared by the preparation method of the first object of the present application.

[0041] The present application provides a high-temperature-resistant crosslinking agent, which is a phenolic aldehyde resin crosslinking agent obtained by replacing part of phenolic substances with modified phenolic lignin and co-reacting with aldehydes and organic bentonite. The inventors of the present application found in research that lignin structure has both phenolic hydroxyl and aldehyde groups. Using lignin to replace phenol in the preparation process of phenolic aldehyde resin can not only reduce costs, alleviate dependence on petroleum products, and reduce environmental pollution, but also reduce free aldehyde content and improve the temperature resistance of the crosslinking agent and further prepared plugging agent. Meanwhile, modified phenolic aldehyde resin needs to be added with bentonite, which can be uniformly dispersed in the gel liquid system to avoid agglomeration. On the one hand, it can play the role of nano-enhanced filler and improve the strength of the plugging agent obtained after gelation using the crosslinking agent; and on the other hand, it can interact with modified phenolic lignin to increase the toughness of the plugging agent and improve the plugging performance. The high-temperature-resistant crosslinking agent has high decomposition temperature and hydroxymethyl content, and low free aldehyde content; can be crosslinked with at least one of a variety of natural or synthetic polymers to form a three-dimensional network structure, and can be controlled to gel in a wide temperature range (90-350℃), which is suitable for efficient development of different oil reservoirs. Through modification of the crosslinking agent, the plugging strength, toughness, plugging efficiency and effective period of the plugging and adjusting system are significantly improved, which meets the performance and economic requirements of field construction, and has high practicability.

[0042] The third object of the present application is to provide an oil field plugging agent prepared by using the high-temperature-resistant crosslinking agent of the second object of the present application, which is prepared from raw materials comprising:

[0043] Main agent, high-temperature-resistant crosslinking agent, stabilizer and preparation water

[0044] The total weight of the raw materials is 100%, and the content of the main agent is 0.01-10wt%;

[0045] The content of the main agent is 0.01-10wt%;

[0046] The content of the high-temperature-resistant crosslinking agent is 1-4wt%;

[0047] The content of the stabilizer is 0.001-0.1wt%;

[0048] To further obtain better results, it is preferred that:

[0049] The content of the main agent is 0.1-6.5wt%;

[0050] The content of the high-temperature-resistant crosslinking agent is 1.2-3wt%;

[0051] The content of the stabilizer is 0.02-0.05wt%.

[0052] In the present application, the amount of the prepared water is added to make the above components in the range.

[0053] Preferably,

[0054] The main agent is selected from at least one of polyacrylamide, polyvinyl alcohol, lignin, tannin, extract of tannin, sodium humate or cellulose; and / or

[0055] The stabilizer is selected from at least one of sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium dithionite, erythorbic acid or thiourea; and / or

[0056] In the present application, the prepared water is not specifically limited, and can be river water, lake water, seawater, underground water, artificial water, oilfield produced water and the like, and is preferably water with a salinity of less than 50000mg / L.

[0057] The fourth object of the present application is to provide a preparation method of the oilfield plugging agent of the third object of the present application, and the method comprises the following steps:

[0058] (1) under stirring, the main agent and the stabilizer are added to the prepared water to be fully dissolved to prepare a mixed solution;

[0059] (2) then, the high-temperature resistant crosslinking agent is added dropwise into the mixed solution, and after being uniformly mixed, the pH value is adjusted to obtain the oilfield plugging agent.

[0060] Preferably, in step (1), the method for fully dissolving adopts the conventional dissolving means in the prior art, such as in the present application, for the main agent being macromolecules such as polyacrylamide and polyvinyl alcohol which are easy to dissolve in water, the stirring dissolving mode can be directly adopted; for the main agent being macromolecules such as extract of tannin and lignin which are not easy to dissolve in water, a little acid or alkali can be added to adjust the pH value of the system, and the stirring mode is adopted to make the above macromolecules dissolve in water.

[0061] Preferably, in step (2), the pH value is adjusted to 8-11, and preferably the pH value is adjusted to 9-10.

[0062] In the present application, whether the pH value needs to be adjusted depends on the pH value of the above channeling plugging system; if the pH value of the above channeling plugging system is in the above range, the pH value can not be adjusted.

[0063] The pH adjusting agent used for adjusting the pH value can be the acid and alkaline substance commonly used for adjusting the pH value in the prior art; preferably, the pH adjusting agent is selected from at least one of dilute hydrochloric acid, dilute sulfuric acid, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium acetate and ammonia water.

[0064] In the present application, the specific substance of the pH regulator added and the amount are selected and adjusted according to the acid and alkali condition of the above-mentioned channeling system, so that the pH value in the above-mentioned channeling system is within the above-mentioned limited pH value range.

[0065] Preferably, in the present application, the amount of the pH regulator added is 0.01-2wt% based on the total weight of the raw material; more preferably, 0.1-1.2wt%.

[0066] The fifth object of the present application is to provide the application of the oil field plugging agent of the third object of the present application in oil extraction.

[0067] Compared with the prior art, the present application has the following advantages:

[0068] The high-temperature resistant crosslinking agent has a high decomposition temperature and a high hydroxymethyl content, and a low free aldehyde content; can be crosslinked with at least one of a plurality of natural or synthetic polymers to form a three-dimensional network structure, and can be controlled to gel in a wide temperature range (90-350℃), and is suitable for efficient development of different oil reservoirs. Through modification of the crosslinking agent, the plugging strength, toughness, plugging efficiency and effective period of the plugging and adjusting system are significantly improved, meeting the performance and economic requirements of field construction, and having high practicability. DETAILED DESCRIPTION

[0069] The present application will be specifically described below in combination with specific examples. It is necessary to point out here that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments of the present application made by those skilled in the art according to the content of the present application still belong to the protection scope of the present application.

[0070] Raw material sources:

[0071] The polyacrylamide is purchased from Shandong Baomo Biological Chemical Co., Ltd., and the effective content is about 88wt%, and the weight average molecular weight is 15 million.

[0072] The polyvinyl alcohol is purchased from Zibo Shengda Chemical Technology Co., Ltd., and the hydrolysis degree is 97%.

[0073] The tannin extract is purchased from Shandong Xinnuo Chemical Co., Ltd., and the effective content is 92wt%.

[0074] The enzymatic hydrolysis lignin is purchased from Shandong Longli Biological Technology Co., Ltd., and the effective content is 91wt%.

[0075] The alkali lignin is purchased from Balingwei Technology Co., Ltd.

[0076] Phenol formaldehyde resin crosslinker was purchased from Shandong Dongying Haoyu Chemical Co., Ltd., and the effective content was about 50wt%.

[0077] Phenol, aldehyde, stabilizer were purchased from Balingwei Technology Co., Ltd.

[0078] Organobentonite was purchased from Zhejiang Fenghong New Material Co., Ltd.

[0079] Test method:

[0080] Methylol and free aldehyde content:

[0081] The methylol content was detected according to the national standard GB / T 14074.17-2017 "Wood Adhesives and Resins-Determination of Methylol Content", and the free aldehyde content was detected according to the national standard GB / T 14074.16-2017 "Wood Adhesives and Resins-Determination of Free Aldehyde Content".

[0082] Decomposition temperature test:

[0083] Phenol formaldehyde resin was preheated at 70℃ for 25min to remove solvent to prepare DSC test sample, and the DSC heating rate was 5℃ / min, and the heating range was room temperature to 700℃.

[0084] Strength test:

[0085] The gel strength was tested by breakthrough vacuum degree method. The specific operation was as follows: the formed gel was loaded into the test bottle of breakthrough vacuum degree experimental device, 1mL of pipette tip was inserted into the surface of the gel 1cm below, the vacuum pump was started, and the knob was slowly adjusted to increase the vacuum degree of the system. When the air broke through the gel, the maximum reading of the vacuum degree on the vacuum table was the breakthrough vacuum degree of the gel. Each sample was repeated for 3 times, and the arithmetic mean value was taken as the final strength value.

[0086] Sealing rate test:

[0087] The simulated core was filled and the core was saturated with water. First, water was injected into the core at a certain flow rate, and the core permeability before plugging (k0) was measured. Then, under the condition of gas-liquid ratio 1:1, different plugging agents were injected into the core at an injection rate of 2mL / min, and after stabilization (gelation), the heating jacket was heated to a specified temperature for subsequent displacement phase displacement. Finally, the core permeability after plugging (k') was measured by water injection. The sealing rate was taken as the parameter to represent the plugging effect of the plugging agent, and the calculation formula of the sealing rate was Wherein, k0 is the permeability before plugging, μm 2 ; k' is the permeability after plugging, μm 2 .

[0088] The heating temperature of the heating jacket corresponds to the required temperature of the displacement phase to be simulated, which can be water or water vapor.

[0089] Dehydration rate test method:

[0090] After the high-temperature stability test reaction, the volume of free water outside the colloid in the reactor is measured, and the dehydration rate is the ratio of the volume of free water to the total volume of the gel-forming liquid. Both volumes are measured at room temperature.

[0091] Preparation Example 1

[0092] Preparation of high-temperature resistant crosslinking agent TR-1

[0093] (1) 60.1 g of water and 3.5 g of KOH were added to a three-necked flask equipped with a stirrer and a condenser, stirred uniformly to prepare a KOH solution; then the system was heated to 90°C, and 29 g of enzymatic lignin and 7.4 g of phenol were added under stirring, and the stirring was continued for 1.2 h. After the reaction was completed, the system was cooled to room temperature to obtain the product phenolated lignin.

[0094] (2) 0.52 g of phenolated lignin, 2.05 g of resorcinol, 7.6 g of formaldehyde, 0.8 g of NaOH, 1.6 g of organic bentonite (octadecyltrimethylammonium chloride as intercalating agent), and 87.43 g of water were added to a three-necked flask equipped with a reflux tube and a stirrer, and pre-mixed under stirring at 250 rpm; then heated to 80°C and stirred at 700 rpm for 30 min, then stopped heating;

[0095] (3) After the reaction was completed, the system was distilled under reduced pressure until the solid content was 52%, to obtain the high-temperature resistant crosslinking agent TR-1.

[0096] Test results show that the hydroxymethyl content of the high-temperature resistant crosslinking agent TR-1 is 32.2%, the free aldehyde content is 0.27%, and the initial decomposition temperature is about 369°C, which is 119°C higher than that of the above-mentioned unmodified ordinary phenolic resin.

[0097] Preparation Example 2

[0098] Preparation of high-temperature resistant crosslinking agent TR-2

[0099] (1) 68.6 g of water and 2.3 g of KOH were added to a three-necked flask equipped with a stirrer and a condenser, stirred uniformly to prepare a KOH solution; then the system was heated to 88°C, and 22 g of enzymatic lignin and 7.1 g of phenol were added under stirring, and the stirring was continued for 1 h. After the reaction was completed, the system was cooled to room temperature to obtain the product phenolated lignin.

[0100] (2) In a three-necked flask equipped with reflux tube and stirrer, 0.46 g of phenolated lignin, 1.84 g of resorcinol, 5.3 g of formaldehyde, 0.75 g of NaOH, 1.2 g of organic bentonite (hexadecyltrimethylammonium bromide as intercalating agent) and 90.45 g of water were added, and pre-mixed under stirring at 250 rpm; then the temperature was raised to 78°C, and stirring was carried out at 700 rpm for 30 min, after which heating was stopped;

[0101] (3) After the reaction was completed, the product was obtained by distillation under reduced pressure until the solid content was 50%, to obtain the high-temperature resistant crosslinking agent TR-2.

[0102] It was tested that the hydroxymethyl content of the high-temperature resistant crosslinking agent TR-2 was 30.8%, the free aldehyde content was 0.33%, and the initial decomposition temperature was about 351°C, which was increased by 101°C compared with the above-mentioned purchased unmodified ordinary phenolic resin.

[0103] Preparation Example 3

[0104] Preparation of high-temperature resistant crosslinking agent TR-3

[0105] (1) 53 g of water and 6 g of KOH were added to a three-necked flask equipped with a stirrer and a condenser, and stirred uniformly to prepare a KOH solution; then the system was heated to 88°C, and 33 g of alkali lignin and 8 g of phenol were added under stirring, and the stirring was continued for 1 h; after the reaction was completed, the system was cooled to room temperature to obtain the product phenolated lignin.

[0106] (2) In a three-necked flask equipped with reflux tube and stirrer, 0.6 g of phenolated lignin, 2.8 g of phenol, 6 g of acetaldehyde, 1 g of sodium bicarbonate, 0.81 g of organic bentonite (tetradecyltrimethylammonium chloride as intercalating agent) and 88.79 g of water were added, and pre-mixed under stirring at 200 rpm; then the temperature was raised to 81°C, and stirring was carried out at 600 rpm for 20 min, after which heating was stopped;

[0107] (3) After the reaction was completed, the product was obtained by distillation under reduced pressure until the solid content was 52%, to obtain the high-temperature resistant crosslinking agent TR-3.

[0108] It was tested that the hydroxymethyl content of the high-temperature resistant crosslinking agent TR-3 was 26.1%, the free aldehyde content was 0.45%, and the initial decomposition temperature was about 345°C, which was increased by 95°C compared with the above-mentioned purchased unmodified ordinary phenolic resin.

[0109] Example 1

[0110] In 80g of prepared water with a salinity of 8000mg / L, 0.56g of polyacrylamide, 0.022g of erythorbic acid are added, and stirred at a speed of 500r / min until uniformly dissolved; 1.2g of high-temperature resistant crosslinking agent TR-2 is slowly added dropwise, and then dilute hydrochloric acid is added to adjust the pH value to 9.5, and then prepared water with a salinity of 8000mg / L is added to 100g, and stirred uniformly to obtain a polyacrylamide-high-temperature resistant oil field plugging agent. The polyacrylamide-high-temperature resistant oil field plugging agent has a strength of 0.089MPa after gelation at 115℃, does not break gel for 56 days at 115℃, has a dehydration rate of 3.9%, and a plugging rate of 99.82%.

[0111] Example 2

[0112] In 80g of prepared water with a salinity of 15000mg / L, 2.6g of polyvinyl alcohol, 0.028g of thiourea are added, and stirred at a speed of 500r / min until uniformly dissolved; 2.1g of high-temperature resistant crosslinking agent TR-1 is slowly added dropwise, and then sodium bicarbonate is added to adjust the pH value to 9, and then prepared water with a salinity of 15000mg / L is added to 100g, and stirred uniformly to obtain a polyvinyl alcohol-high-temperature resistant oil field plugging agent. The polyvinyl alcohol-high-temperature resistant oil field plugging agent has a strength of 0.079MPa after gelation at 200℃, does not break gel for 41 days at 200℃, has a dehydration rate of 4.6%, and a plugging rate of 99.02%.

[0113] Example 3

[0114] In 80g of prepared water with a salinity of 12000mg / L, 6.6g of tannin, 0.02g of thiourea are added, and then sodium hydroxide is added to adjust the pH value of the system to 9, and stirred at a speed of 500r / min until uniformly dissolved; 2.6g of high-temperature resistant crosslinking agent TR-1 is slowly added dropwise, and then sodium hydroxide is added to adjust the pH value to 10, and then prepared water with a salinity of 12000mg / L is added to 100g, and stirred uniformly to obtain a tannin-high-temperature resistant oil field plugging agent; the tannin-high-temperature resistant oil field plugging agent has a strength of 0.09MPa after gelation at 350℃, does not break gel for 7 days, has a dehydration rate of 6.1%, and a plugging rate of 99.66%.

[0115] Example 4

[0116] In 80g of prepared water with a salinity of 5000mg / L, 5.2g of enzymatic lignin, 0.024g of thiourea are added, then sodium hydroxide is added to make the pH value of the system 10, and stirring is carried out at a speed of 500r / min until uniform dissolution; 2.3g of high-temperature resistant crosslinking agent TR-1 is slowly added dropwise, then sodium hydroxide is added to adjust the pH value to 10.5, and prepared water with a salinity of 5000mg / L is added to make the total volume 100g, and stirring is carried out until uniform. A lignin-high-temperature resistant oil field plugging agent is obtained. The strength after gelation reaches 0.088MPa at 300℃, and the gel is not broken at 300℃ for 60 days, the dehydration rate is 4.6%, and the plugging rate is 99.82%.

[0117] Example 5

[0118] In 80g of prepared water with a salinity of 30000mg / L, 8.8g of alkali lignin, 0.024g of sodium sulfite are added, then sodium hydroxide is added to make the pH value of the system 9, and stirring is carried out at a speed of 500r / min until uniform dissolution; 3.5g of high-temperature resistant crosslinking agent TR-3 is slowly added dropwise, then sodium hydroxide is added to adjust the pH value to 10, and prepared water with a salinity of 30000mg / L is added to make the total volume 100g, and stirring is carried out until uniform. A lignin-high-temperature resistant oil field plugging agent is obtained. The strength after gelation reaches 0.081MPa at 250℃, and the gel is not broken at 250℃ for 60 days, the dehydration rate is 6.8%, and the plugging rate is 99.26%.

[0119] Comparative Example 1

[0120] The experiment is carried out according to the method of Example 1, except that the high-temperature resistant crosslinking agent TR-2 is replaced by unmodified phenolic resin. The obtained plugging agent has a strength after gelation of 0.068MPa at 115℃, and the gel is broken at 115℃ for 21 days, the dehydration rate is 18.3%, and the plugging rate is 86.56%.

[0121] Comparative Example 2

[0122] The experiment is carried out according to the method of Example 2, except that the high-temperature resistant crosslinking agent TR-1 is replaced by unmodified phenolic resin. The obtained plugging agent has a strength after gelation of 0.052MPa at 200℃, and the gel is broken at 200℃ for 18 days, the dehydration rate is 14.7%, and the plugging rate is 75.98%.

[0123] Comparative Example 3

[0124] The experiment is carried out according to the method of Example 3, except that the high-temperature resistant crosslinking agent TR-1 is replaced by unmodified phenolic resin. The obtained plugging agent has a strength after gelation of 0.072MPa at 350℃, and the gel is broken at 350℃ for 7 days, the dehydration rate is 33.9%, and the plugging rate is 81.26%.

[0125] Comparative Example 4

[0126] The experiment was carried out according to the method of Example 5, except that the high-temperature-resistant crosslinking agent TR-3 was replaced by unmodified phenolic resin. The obtained plugging agent had a post-gel strength of 0.057 MPa at 250°C, was broken at 300°C after 60 days, had a dehydration rate of 29.3%, and a plugging rate of 78.69%.

[0127] Comparative Example 5

[0128] Preparation of high-temperature-resistant crosslinking agent TR-4:

[0129] The preparation method of the high-temperature-resistant crosslinking agent TR-4 was the same as that of the high-temperature-resistant crosslinking agent TR-2, except that the organic bentonite was not contained in the raw materials, and the amount of water added was 91.65 g.

[0130] The experiment was carried out according to the method of Example 1, except that the high-temperature-resistant crosslinking agent TR-2 was replaced by the high-temperature-resistant crosslinking agent TR-4. The obtained plugging agent had a post-gel strength of 0.082 MPa at 115°C, was not broken at 115°C after 48 days, had a dehydration rate of 12.3%, and a plugging rate of 88.28%.

[0131] Comparative Example 6

[0132] Preparation of high-temperature-resistant crosslinking agent TR-5:

[0133] The preparation method of the high-temperature-resistant crosslinking agent TR-5 was the same as that of the high-temperature-resistant crosslinking agent TR-2, except that the unmodified enzymatic lignin was used to replace the phenolic lignin in the raw materials.

[0134] The experiment was carried out according to the method of Example 1, except that the high-temperature-resistant crosslinking agent TR-2 was replaced by the high-temperature-resistant crosslinking agent TR-5. The obtained plugging agent had a post-gel strength of 0.070 MPa at 115°C, was not broken at 115°C after 31 days, had a dehydration rate of 19.1%, and a plugging rate of 86.08%.

[0135] Comparative Example 7

[0136] Preparation of high-temperature-resistant crosslinking agent TR-6:

[0137] The preparation method of the high-temperature-resistant crosslinking agent TR-6 was the same as that of the high-temperature-resistant crosslinking agent TR-2, except that the amount of the organic bentonite (cetyltrimethylammonium bromide as intercalating agent) added in the raw materials was 4.2 g, and the amount of water added was 87.45 g.

[0138] The experiment was carried out according to the method of Example 1, except that the high-temperature-resistant crosslinking agent TR-2 was replaced by the high-temperature-resistant crosslinking agent TR-6, and the obtained plugging agent had a strength of 0.081 MPa after gelation at 115 DEG C, was not broken for 50 days at 115 DEG C, had a dehydration rate of 9.6%, and had a plugging rate of 90.11%.

[0139] Comparative Example 8

[0140] Preparation of high-temperature-resistant crosslinking agent TR-7:

[0141] The preparation method of the high-temperature-resistant crosslinking agent TR-7 is the same as that of the high-temperature-resistant crosslinking agent TR-2, except that the addition amount of the phenolated lignin in the raw material is 3.46 g, and the addition amount of water is 87.45 g.

[0142] The experiment was carried out according to the method of Example 1, except that the high-temperature-resistant crosslinking agent TR-2 was replaced by the high-temperature-resistant crosslinking agent TR-7, and the obtained plugging agent had a strength of 0.077 MPa after gelation at 115 DEG C, was not broken for 36 days at 115 DEG C, had a dehydration rate of 16.1%, and had a plugging rate of 87.23%.

[0143] As can be seen from the comparison between the examples and the comparative examples, the present application provides a preparation method of a high-temperature-resistant crosslinking agent for oil fields, the high-temperature-resistant crosslinking agent, and application thereof. The high-temperature-resistant crosslinking agent has a relatively high decomposition temperature and hydroxymethyl content, and a relatively low free aldehyde content; can be crosslinked with at least one of various natural or synthetic polymers to form a three-dimensional network structure, and can be controllably gelled in a relatively wide temperature range (90-350 DEG C), and is suitable for efficient development of different oil reservoirs. Through modification of the crosslinking agent, the plugging strength, toughness, plugging efficiency, and effective period of the plugging and adjusting system are obviously improved, the performance and economic requirements of field construction are met, and the practicality is relatively high.

[0144] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A high temperature resistant crosslinker prepared oilfield plugging agent, characterized in that, The plugging agent is prepared from raw materials comprising the following components; The main agent, the high-temperature resistant crosslinking agent, the stabilizer and the prepared water; The total weight of the raw materials is 100%, The content of the main agent is 0.01-10wt%; The content of the high-temperature resistant crosslinking agent is 1-4wt%; The content of the stabilizer is 0.001-0.1wt%; The preparation method of the high-temperature resistant crosslinking agent comprises the following steps: (1) After lignin and phenol are added into an alkali catalyst solution for contact reaction, post-treatment is performed to obtain phenolated lignin; (2) After the phenolated lignin, phenol, aldehyde, polycondensation catalyst, organic bentonite and water are premixed, heating reaction is performed; after the reaction is completed, distillation and concentration are performed to obtain the high-temperature resistant crosslinking agent; The mass ratio of the phenolated lignin, the phenol and the aldehyde is (0.05-0.10):(0.2-0.5):1; In step (2), in the reaction system, the concentration of the aldehyde is 4.5-9wt%; the concentration of the organic bentonite is 0.5-2.5wt%; In step (2), the heating reaction is performed for 15-45min.

2. The oilfield plugging agent according to claim 1, characterized in that, The total weight of the raw materials is 100%, The content of the main agent is 0.1-6.5wt%; The content of the high-temperature resistant crosslinking agent is 1.2-3wt%; The content of the stabilizer is 0.02-0.05wt%.

3. The oilfield plugging agent according to claim 1, characterized in that: The main agent is at least one selected from polyacrylamide, polyvinyl alcohol, lignin, tannin, tannin extract, humic acid sodium and cellulose; and / or The stabilizer is at least one selected from sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium hydrosulfite, erythorbic acid and thiourea; and / or The mineralization degree of the prepared water is less than 50000mg / L.

4. The oilfield plugging agent according to claim 1, characterized in that: In the preparation method of the high-temperature resistant crosslinking agent, in step (1), The lignin is at least one selected from alkali lignin, enzymatic hydrolysis lignin, chlorinated lignin, steam explosion lignin and sulfur lignin; and / or The phenol is at least one selected from phenol, hydroquinone, resorcinol and catechol; and / or The alkali catalyst in the alkali catalyst solution is at least one selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate and ammonia water.

5. The oilfield plugging agent according to claim 1, characterized in that: In the preparation method of the high-temperature resistant crosslinking agent, in step (1) of the contact reaction, in the reaction system, The concentration of the lignin is 20-35wt%; The mass ratio of the phenol to the lignin is 0.2-0.4:1; The concentration of the alkali catalyst is 2-10wt%; The reaction temperature is 88-92℃, and the reaction time is 1-1.5h.

6. The oilfield plugging agent according to claim 1, characterized in that: In the preparation method of the high-temperature resistant crosslinking agent, in step (2), The phenol is at least one selected from phenol, hydroquinone, resorcinol and catechol; and / or The aldehyde is at least one selected from formaldehyde, acetaldehyde and furfural; and / or The polycondensation catalyst is selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate or ammonia.

7. The oilfield plugging agent according to claim 1, wherein: In step (2), In the reaction system, The concentration of the polycondensation catalyst is 0.5-1wt%.

8. The oilfield plugging agent according to claim 7, wherein: In step (2), In the reaction system, The concentration of the aldehyde is 5-8%; The concentration of the organic bentonite is 0.5-2%.

9. The oilfield plugging agent according to claim 8, wherein: The concentration of the organic bentonite is 1.1-1.6wt%.

10. The oilfield plugging agent according to claim 8, wherein: In step (2), The temperature of the heating reaction is 78-82℃; The distillation is reduced pressure distillation, and the distillation is performed until the solid content is ≥40%.

11. The method of preparing the oilfield plugging agent according to any one of claims 1-10, characterized in that, The method comprises the following steps: (1) Under stirring, main agent and stabilizer are added into prepared water to dissolve sufficiently, to prepare a mixed solution; (2) Then, a high-temperature resistant crosslinking agent is added dropwise into the mixed solution, and after mixing uniformly, the pH value is adjusted, to obtain the oilfield plugging agent.

12. The preparation method of the oilfield plugging agent according to claim 11, wherein: In step (2), the pH value is adjusted to 8-11.

13. The preparation method of the oilfield plugging agent according to claim 12, wherein: The pH value is adjusted to 9-10.

14. The oilfield plugging agent according to any one of claims 1-10, for use in oil production.