Water shutoff agent and its application

Abstract

The application provides a water plugging agent and application thereof. The water plugging agent comprises an epoxy resin, amineated lignin and water, wherein the amineated lignin is prepared by the following steps: 1) mixing lignin and water, adjusting the pH value to be alkaline to obtain a lignin aqueous solution; 2) placing the lignin aqueous solution at a first temperature, adding an amineated modifier thereto, reacting at a second temperature, and then adding a reaction termination stabilizer to obtain an amineated lignin reaction liquid.

Description

Technical Field

[0001] This invention relates to the field of water shut-off in oil fields, and particularly to a water shut-off agent and its application. Background Technology

[0002] Injecting water-blocking agents into oil and water wells can seal high-permeability channels near oil wells, adjust the water absorption profile of water wells, and thus improve oil recovery. Currently, various types of plugging agents, such as gels, foams, and particles, have undergone extensive field trials across China. However, with increasingly complex oil production environments—for example, reservoir temperatures in the Tarim River Oilfield often exceed 130℃, and salinity exceeds 200,000 salinity (20×10⁻⁶)—… 4 In the face of this situation, existing plugging agents have also revealed significant shortcomings: gel-type plugging agents have insufficient strength and short shelf life; granular plugging agents have poor injectability; there are few domestically produced foam plugging agents available, and foreign foam plugging agents are too expensive.

[0003] Lignin originates from natural plants and has a phenylpropane structure. In industry, lignin mainly comes from byproducts of the pulp and paper industry, typically in the form of alkali lignin, sulfate lignin, and lignin sulfonate. Compared to polymers, lignin has a wider range of sources and is inexpensive, making it an ideal base material for oilfield additives. However, lignin also has several drawbacks: its molecular weight is relatively low, resulting in lower strength after cross-linking with ethers, aldehydes, etc.; the pulping waste liquor used has a complex composition, high impurity content, and poor controllability. Summary of the Invention

[0004] One aspect of the present invention provides a water-blocking agent comprising epoxy resin, aminated lignin, and water.

[0005] In one specific embodiment, the epoxy equivalent of the epoxy resin is 185 to 550.

[0006] In one specific embodiment, the epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, waterborne epoxy resin, waterborne epoxy resin emulsion, and phenolic modified epoxy resin.

[0007] In one specific embodiment, the epoxy resin is at least one of South Asia epoxy resin NPEL128, waterborne epoxy resin F0716, waterborne phenolic modified epoxy resin emulsion F0704, and waterborne phenolic epoxy resin F65.

[0008] In one specific embodiment, the mass ratio of the epoxy resin to the aminated lignin is 1:(0.74 to 12.3).

[0009] In one specific embodiment, the aminated lignin is prepared by the following steps:

[0010] 1) Mix lignin and water, adjust the pH to alkaline, and obtain an aqueous solution of lignin;

[0011] 2) Place the lignin aqueous solution at a first temperature, add an amination modifier to it, react at a second temperature, and then add a reaction termination stabilizer to obtain an amination lignin reaction solution.

[0012] In one specific embodiment, the lignin is at least one of sodium lignin sulfonate, alkali lignin, and lignin-containing black liquor for papermaking.

[0013] In one specific embodiment, the amine modifier comprises an aldehyde, an amine, and a dispersant, wherein the aldehyde is at least one selected from formaldehyde, furfural, glyoxal, and glutaraldehyde; the amine is at least one selected from diethylenetriamine, dicyandiamide, triethylenetetramine, ethylenediamine, methylcyclohexanediamine, p-phenylenediamine, and m-phenylenediamine; and the dispersant is at least one selected from sodium silicate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and polyethylene glycol.

[0014] In one specific implementation, in step 1), the pH value is adjusted to 10 to 14.

[0015] In one specific embodiment, in step 1), the total mass of the lignin aqueous solution is 100%, and the lignin content is 10% to 35%.

[0016] In one specific embodiment, the aldehyde and amine are added independently to the lignin aqueous solution over a period of 1.5 to 3 hours.

[0017] In one specific embodiment, the first temperature and the second temperature are independently between 30 and 80°C.

[0018] In one specific embodiment, in step 2), the reaction time at the second temperature is 0 to 5 hours.

[0019] In one specific embodiment, the reaction termination stabilizer is urea.

[0020] In one specific embodiment, the amount added is 2% to 10% relative to the lignin content.

[0021] The second invention provides the application of the water-blocking agent according to any one of the first inventions in oilfield water plugging.

[0022] The beneficial effects of this invention are:

[0023] This invention overcomes the problems of poor sealing effect caused by short action time, poor high temperature and salt resistance, and low strength of existing water-blocking agents. It utilizes amine-modified lignin as the main component, cross-linking and curing it with epoxy resin at high temperature to form an aminated lignin-epoxy resin adhesive. The water-blocking agent of this invention features high temperature and high salt resistance, long effective period, and high strength.

[0024] The water-blocking agent provided by this invention can be applied in two steps. The amination modification of lignin can be processed in the factory, and on-site, only the modified amination lignin needs to be mixed with epoxy resin. Therefore, it can avoid the hazards of formaldehyde and papermaking black liquor to on-site operations. At the same time, this water-blocking agent is suitable for high temperature and high salt environments, has an adjustable curing speed, and high strength after curing. Compared with other water-blocking agents, it has the following outstanding advantages and effects:

[0025] 1. The water-blocking agent of the present invention has high gel strength and excellent temperature and salt resistance.

[0026] 2. The water-blocking agent of the present invention can maintain its complete external shape and internal structure under harsh conditions of high temperature and high salt. The high temperature and high salt environment will increase the compressive strength of the gel formed by curing, and it has excellent mechanical properties.

[0027] 3. This invention is carried out in two steps, which is safe to operate and has minimal hazards. It solves the problem of on-site compounding of reagents in existing technologies and avoids the hazards to on-site operators caused by formaldehyde and black liquor (hazardous chemicals) in papermaking. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0029] Example 1

[0030] 1) Mix 1000g of sodium lignosulfonate with 3000g of water, stir to dissolve, and adjust the pH to 10 with sodium hydroxide to obtain an alkaline aqueous solution of sodium lignosulfonate with a mass concentration of 25%.

[0031] 2) Heat the alkaline aqueous solution of sodium lignosulfonate to 60°C, then add 400g of a 37wt% formaldehyde aqueous solution (of which, based on the mass of sodium lignosulfonate, the amount of formaldehyde is 14.8wt%), 300g of diethylenetriamine (of which, based on the mass of sodium lignosulfonate, the amount of diethylenetriamine is 30%), and 50g of sodium silicate (of which, based on the mass of sodium lignosulfonate, the amount of sodium silicate is 5%). The formaldehyde aqueous solution and diethylenetriamine are added separately to the alkaline aqueous solution of sodium lignosulfonate. The addition time in the solution was 2 hours. After the addition was completed, the reaction was continued at 60°C for another 2 hours. Then, 50g of urea was added, and the solution was cooled to below 25°C by a circulating water cooling system while stirring. The resulting aminated lignin sulfonate reaction solution was obtained. The amount of aminated lignin sulfonate was calculated based on the total amount of the reaction raw materials: sodium lignin sulfonate, formaldehyde, and diethylenetriamine. The amount of aminated lignin sulfonate obtained was 1448g, and the amount of the aminated lignin sulfonate reaction solution was 4800g. Therefore, the content of aminated lignin sulfonate in the aminated lignin sulfonate reaction solution was 30.2%.

[0032] 3) Mix 20g of South Asia epoxy resin NPEL128 (epoxy equivalent = 230), 100g of aminated lignin sulfonate reaction solution and 300g of water, and stir evenly with a mixer to obtain a lignin-epoxy resin mixture, wherein the mass ratio of South Asia epoxy resin to aminated lignin sulfonate is 1:1.5.

[0033] 4) To simulate the formation solidification environment, a pressure-resistant pipe and a hydrothermal reactor were used as reaction vessels. The lignin-epoxy resin mixture was transferred into the pressure-resistant pipe, sealed, and placed in an electric heating drying oven at 150°C for 4 hours to form a lignin-epoxy resin adhesive.

[0034] The lignin-epoxy resin adhesive was aged in a saline solution with a mineralization of 210,000 for 60 days at 150°C to obtain aged lignin-epoxy resin adhesive.

[0035] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive was measured using a universal testing machine (INSTRON 3366, USA) (referred to as pre-aging compressive strength and post-aging compressive strength, respectively). Both the lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive samples used in the test were cylindrical, with a diameter and height of 20 mm and 30 mm, respectively, and a compression ratio of 60% was set. The results are shown in Table 1.

[0036] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0037] Wherein, the dehydration ratio = the volume of water removed after aging / the volume of lignin-epoxy resin glue before aging.

[0038] Example 2

[0039] 1) Mix 5 kg of alkali lignin with 12 kg of water, stir to dissolve, adjust the pH to 14 with sodium hydroxide, stir to dissolve, and obtain an alkaline aqueous solution of alkali lignin with a mass concentration of 29.4%.

[0040] 2) Heat the alkaline aqueous solution of alkali lignin to 50℃, then add 0.75 kg of furfural (of which, based on the mass of alkali lignin, furfural accounts for 100% and the amount used is 15 wt%), 0.4 kg of dicyandiamide (of which, based on the mass of alkali lignin, dicyandiamide accounts for 100% and the amount used is 8 wt%), 0.6 kg of triethylenetetramine (of which, based on the mass of alkali lignin, triethylenetetramine accounts for 100% and the amount used is 12 wt%), and 50 g of sodium dodecylbenzenesulfonate (of which, based on the mass of alkali lignin, sodium dodecylbenzenesulfonate accounts for 100% and the amount used is 1 wt%). Aldehyde, dicyandiamide, and triethylenetetramine were added to the alkaline aqueous solution of alkali lignin for 2 hours each. After addition, the reaction was continued at 50°C for 3 hours. Then, 100g of urea was added, and the solution was cooled to below 25°C by a circulating water cooling system while stirring, to obtain an aminated alkali lignin reaction solution. The amount of aminated alkali lignin was calculated based on the total amount of the reaction raw materials alkali lignin, furfural, dicyandiamide, and triethylenetetramine. That is, the amount of aminated alkali lignin obtained was 6.75kg, and the amount of aminated alkali lignin reaction solution was 18.9kg. Therefore, the content of aminated alkali lignin in the aminated alkali lignin reaction solution was 35.7%.

[0041] 3) Mix 4.35g of waterborne epoxy resin F0716 (epoxy equivalent = 185, Shenzhen Yoshida Chemical), 150g of aminated alkali lignin reaction solution and 300g of water, and stir evenly with a mixer to obtain a lignin-epoxy resin mixture, wherein the mass ratio of waterborne epoxy resin F0716 to aminated alkali lignin is 1:12.3;

[0042] 4) To simulate the formation solidification environment, a pressure-resistant pipe and a hydrothermal reactor were used as reaction vessels. The lignin-epoxy resin mixture was transferred into the pressure-resistant pipe, sealed, and placed in an electric heating drying oven at 130°C for 8.0 hours to form a lignin-epoxy resin adhesive.

[0043] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged at 130°C for 60 days to obtain aged lignin-epoxy resin adhesive.

[0044] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0045] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0046] Example 3

[0047] In step 3), the amount of waterborne epoxy resin F0716 is 15g, wherein the mass ratio of waterborne epoxy resin F0716 to aminated alkali lignin is 1:3.57; in step 4), it is cured at 150°C for 5.5h to form lignin-epoxy resin adhesive. Other steps are the same as in Example 2.

[0048] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged at 150°C for 60 days to obtain aged lignin-epoxy resin adhesive.

[0049] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0050] Example 4

[0051] In step 3), the amount of waterborne epoxy resin F0716 is 35g, wherein the mass ratio of waterborne epoxy resin F0716 to aminated alkali lignin is 1:1.53; in step 4), it is cured at 160℃ for 3.0h to form lignin-epoxy resin adhesive. Other steps are the same as in Example 2.

[0052] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged at 160°C for 60 days to obtain aged lignin-epoxy resin adhesive.

[0053] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0054] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0055] Example 5

[0056] In step 3), the amount of waterborne epoxy resin F0716 is 66g, wherein the mass ratio of waterborne epoxy resin F0716 to aminated alkali lignin is 1:0.81; in step 4), it is cured at 180°C for 2.0h to form lignin-epoxy resin adhesive. Other steps are the same as in Example 2.

[0057] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged at 180°C for 60 days to obtain aged lignin-epoxy resin adhesive.

[0058] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0059] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0060] Example 6

[0061] 1) Dissolve 5 kg of alkali lignin in 12 kg of water by stirring, adjust the pH to 14 with sodium hydroxide, and stir to dissolve again to obtain an alkaline aqueous solution of alkali lignin with a mass concentration of 29.4%.

[0062] 2) Heat the alkaline aqueous solution of alkali lignin to 80℃, then add 0.2 kg of glyoxal (of which, based on the mass of alkali lignin, glyoxal accounts for 4.0 wt%), 0.2 kg of glutaraldehyde (of which, based on the mass of alkali lignin, glutaraldehyde accounts for 4.0 wt%), 0.5 kg of 37 wt% formaldehyde aqueous solution (of which, based on the mass of alkali lignin, formaldehyde accounts for 3.7 wt%), 0.4 kg of ethylenediamine (of which, based on the mass of alkali lignin, ethylenediamine accounts for 8.0 wt%), and 0.3 kg of methylcyclohexanediamine (of which, based on the mass of alkali lignin, methylcyclohexanediamine accounts for 6.0 wt%). The reaction mixture consisted of 50g of sodium dodecyl sulfate (1.0wt% of which was 100% based on the mass of alkali lignin), and 2h of each component. After addition, the reaction was continued at 80℃ for 3h. Then, 150g of urea was added, and the mixture was cooled to below 25℃ by a circulating water cooling system under stirring to obtain an aminated alkali lignin reaction solution. The amount of aminated alkali lignin was calculated based on the total amount of the reaction raw materials alkali lignin, glyoxal, glutaraldehyde, formaldehyde, ethylenediamine, and methylcyclohexanediamine. The amount of aminated alkali lignin obtained was 6.285kg, and the amount of aminated alkali lignin reaction solution was 18.8kg. Therefore, the content of aminated alkali lignin in the aminated alkali lignin reaction solution was 33.4%.

[0063] 3) Mix 90g of waterborne phenolic modified epoxy resin emulsion F0704 (epoxy equivalent = 460, solid content 50wt%, Shenzhen Yoshida Chemical), 100g of aminated alkali lignin reaction solution and 1378g of water, and stir evenly with a mixer to obtain a lignin-epoxy resin mixture with a solid content (i.e., the total mass of waterborne phenolic modified epoxy resin and aminated alkali lignin) of 5%, wherein the mass ratio of waterborne phenolic modified epoxy resin emulsion F0704 to aminated alkali lignin is 1:0.74;

[0064] 4) To simulate the formation solidification environment, a pressure-resistant pipe and a hydrothermal reactor were used as reaction vessels. The lignin-epoxy resin mixture was transferred into the pressure-resistant pipe, sealed, and placed in an electric heating drying oven at 130°C for 8.0 hours to form a lignin-epoxy resin adhesive.

[0065] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged for 60 days at the corresponding gelation temperature to obtain aged lignin-epoxy resin adhesive.

[0066] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0067] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0068] Example 7

[0069] In step 3), the amount of water used is 463.3g; in step 4), it is cured at 150°C for 4.5h to form a lignin-epoxy resin adhesive. Other steps are the same as in Example 6.

[0070] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged for 60 days at the corresponding gelation temperature to obtain aged lignin-epoxy resin adhesive.

[0071] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0072] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0073] Example 8

[0074] In step 3), the amount of water used is 123.6g; in step 4), it is cured at 180°C for 2.0h to form a lignin-epoxy resin adhesive. Other steps are the same as in Example 6.

[0075] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged for 90 days at the corresponding gelation temperature to obtain aged lignin-epoxy resin adhesive.

[0076] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0077] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0078] Example 9

[0079] 1) Dissolve 5 kg of alkali lignin in 45 kg of water by stirring, adjust the pH to 14 with sodium hydroxide, stir and dissolve again to obtain an alkaline aqueous solution of alkali lignin with a mass concentration of 10%.

[0080] 2) Heat the alkaline aqueous solution of alkali lignin to 30°C, then add 2.7 kg of 37 wt% formaldehyde aqueous solution (of which, based on the mass of alkali lignin, formaldehyde accounts for 20 wt%), 0.5 kg of furfural (of which, based on the mass of alkali lignin, furfural accounts for 10 wt%), 1.0 kg of dicyandiamide (of which, based on the mass of alkali lignin, dicyandiamide accounts for 20 wt%), 0.75 kg of triethylenetetramine (of which, based on the mass of alkali lignin, triethylenetetramine accounts for 15 wt%), and sodium dodecyl sulfate. 50g of alkali lignin (of which, based on the mass of alkali lignin, is 100%, and the amount of sodium dodecyl sulfate is 1.0wt%) was added over a period of 3 hours. Then, 100g of urea was added, and the mixture was cooled to below 25°C under stirring via a circulating water cooling system to obtain an aminated alkali lignin reaction solution. The amount of aminated alkali lignin was calculated based on the total amount of the reaction raw materials alkali lignin, formaldehyde, furfural, dicyandiamide, and triethylenetetramine. The amount of aminated alkali lignin obtained was 8.25kg, and the amount of aminated alkali lignin reaction solution was 55.1kg. Therefore, the content of aminated alkali lignin in the aminated alkali lignin reaction solution was 15%.

[0081] 3) Mix 30g of waterborne phenolic modified epoxy resin emulsion F0704 (epoxy equivalent = 460, solid content 50wt%, Shenzhen Yoshida Chemical), 100g of aminated alkali lignin reaction solution, and 50g of water. Stir evenly with a mixer to obtain a lignin-epoxy resin mixture. The mass ratio of waterborne phenolic modified epoxy resin emulsion F0704 to aminated alkali lignin is 1:1.

[0082] 4) To simulate the formation solidification environment, a pressure-resistant pipe and a hydrothermal reactor were used as reaction vessels. The lignin-epoxy resin mixture was transferred into the pressure-resistant pipe, sealed, and placed in an electric heating drying oven at 170°C for 2 hours to form a lignin-epoxy resin adhesive.

[0083] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged at 170°C for 90 days to obtain aged lignin-epoxy resin adhesive.

[0084] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0085] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0086] Example 10

[0087] 1) Heat 5 kg of papermaking black liquor (pH = 14) with a lignin content of 35% to 65°C. Then add 2.365 kg of 37 wt% formaldehyde aqueous solution (of which, based on the mass of lignin, formaldehyde accounts for 50 wt%), 60 g of polyethylene glycol (PEG1000) (of which, based on the mass of lignin, polyethylene glycol accounts for 3.4%), 1.0 kg of diethylenetriamine (of which, based on the mass of lignin, diethylenetriamine accounts for 57.1%), 100 g of p-phenylenediamine (of which, based on the mass of lignin, p-phenylenediamine accounts for 5.7%), and 100 g of m-phenylenediamine. (Of which, based on the mass of lignin as 100%, the amount of m-phenylenediamine is 5.7%), it was added to the concentrated black liquor of the papermaking solution, with an addition time of 1.5 h for each. After the addition was completed, the reaction was continued at 65℃ for 5 h. Then, 175 g of urea was added, and the mixture was cooled to below 25℃ by a circulating water cooling system under stirring to obtain an aminated lignin reaction solution. The amount of aminated lignin was calculated based on the total amount of the reaction raw materials lignin, formaldehyde, diethylenetriamine, p-phenylenediamine and m-phenylenediamine, that is, the amount of aminated lignin obtained was 3.825 kg, and the amount of aminated lignin reaction solution was 8.8 kg. Therefore, the content of aminated lignin in the aminated lignin reaction solution was 43.5%.

[0088] 2) Mix 40g of waterborne phenolic epoxy resin F65 (epoxy equivalent = 550, Guangzhou Qian'an Chemical Co., Ltd.), 200g of aminated lignin reaction solution, and 200g of water using a mixer to obtain a lignin-epoxy resin mixture, wherein the mass ratio of waterborne phenolic epoxy resin F65 to aminated lignin is 1:2.18.

[0089] 3) To simulate the formation solidification environment, a pressure-resistant pipe and a hydrothermal reactor were used as reaction vessels. The lignin-epoxy resin mixture was transferred into the pressure-resistant pipe, sealed, and placed in an electric heating drying oven at 155°C for 8 hours to form a lignin-epoxy resin adhesive.

[0090] The lignin-epoxy resin adhesive was placed in a saline solution with a mineralization of 210,000 and aged at 155°C for 80 days to obtain aged lignin-epoxy resin adhesive.

[0091] The compressive strength of lignin-epoxy resin adhesive and aged lignin-epoxy resin adhesive (referred to as compressive strength before aging and compressive strength after aging, respectively) was measured using a universal testing machine (INSTRON 3366, USA). The testing procedure was the same as in Example 1, and the results are shown in Table 1.

[0092] Weigh the volume of the lignin-epoxy resin before aging and the volume of water removed from the lignin-epoxy resin after aging, calculate the dehydration ratio, and the results are shown in Table 1.

[0093] Table 1

[0094]

[0095] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A water shutoff agent, comprising an epoxy resin, an aminated lignin, and water; a mass ratio of the epoxy resin to the aminated lignin is 1: (0.74 to 12.3) ; the aminated lignin is prepared by the following steps: 1) mixing lignin and water, adjusting pH value to alkaline, to obtain a lignin aqueous solution; 2) placing the lignin aqueous solution at a first temperature, adding an amination modifier thereto, reacting at a second temperature, and then adding a reaction termination stabilizer, to obtain an aminated lignin reaction solution; wherein the amination modifier comprises an aldehyde, an amine, and a dispersing agent, wherein the aldehyde is at least one of formaldehyde, furfural, glyoxal, and glutaraldehyde, the amine is at least one of diethylene triamine, dicyandiamide, triethylene tetramine, ethylenediamine, methylcyclohexanediamine, p-phenylenediamine, and m-phenylenediamine, and the dispersing agent is at least one of sodium silicate, sodium dodecylbenzenesulfonate, sodium dodecylsulfate, and polyethylene glycol.

2. The water shutoff agent of claim 1, wherein, an epoxy equivalent weight of the epoxy resin is 185 to 550.

3. The water shutoff agent of claim 1, wherein, the epoxy resin is a waterborne epoxy resin.

4. The water shutoff agent of claim 1, wherein, the epoxy resin is a waterborne epoxy resin emulsion.

5. The water shutoff agent of claim 1, wherein, the epoxy resin is at least one of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a phenolic modified epoxy resin.

6. The water shutoff agent of claim 1, wherein, the epoxy resin is at least one of NPEL128 of Nan Ya Epoxy Resin, F0716 of a waterborne epoxy resin, F0704 of a waterborne phenolic modified epoxy resin emulsion, and F65 of a waterborne phenolic epoxy resin.

7. The water shutoff agent of claim 1, wherein, the lignin is at least one of sodium lignosulfonate, alkali lignin, and papermaking black liquor containing lignin.

8. The water shutoff agent of claim 1, wherein, an amount of the aldehyde is 11.7% to 50% based on 100% of a mass of the lignin, an amount of the amine is 14% to 68.5% based on 100% of the mass of the lignin, and an amount of the dispersing agent is 1% to 5% based on 100% of the mass of the lignin.

9. The water shutoff agent of claim 1, wherein, in step 1), the pH value is adjusted to 10 to 14.

10. The water shutoff agent of claim 1, wherein, in step 1), a content of the lignin is 10% to 35% based on 100% of a total mass of the lignin aqueous solution.

11. The water shutoff agent of claim 1, wherein, the aldehyde and the amine are independently added to the lignin aqueous solution within 1.5 to 3 hours; the first temperature and the second temperature are independently 30 to 80°C; in step 2), a reaction time at the second temperature is 0 to 5 hours.

12. The water shutoff agent of claim 1, wherein, the reaction termination stabilizer is urea; an amount of the reaction termination stabilizer is 2% to 10% based on 100% of the mass of the lignin. 13.Use of the water shutoff agent according to any one of claims 1 to 12 in water shutoff in an oilfield.

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