Oilfield plugging agent, its preparation method and use

Abstract

The present invention relates to the field of oil field plugging agents, specifically to a plugging agent for oil field oil extraction, its preparation method and use. The plugging agent comprises lignin amide. The plugging agent can be controllably gelled in a wide range of oil reservoir temperatures, has improved heat resistance, and has the characteristics of high strength, high system viscosity, high plugging strength, high application temperature, etc., effectively reduces the cost of water-proofing and cross-section adjustment systems, meets the requirements for on-site construction characteristics, economy and environmental protection, and is highly practicable.

Description

Detailed Description of the Invention

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Chinese Patent Application No. 202011552715.X filed on December 24, 2020, Chinese Patent Application No. 202011552736.1 filed on December 24, 2020, Chinese Patent Application No. 202011554138.8 filed on December 24, 2020, and Chinese Patent Application No. 202110049341.8 filed on January 14, 2021, the contents of which are incorporated herein by reference.

[0002] [Technical Field] The present invention relates to the technical field of oil field water cutoff, cross section adjustment, steam channeling plugging, and in particular to plugging agents, their preparation methods and uses.

[0003] [Background technology] As development progresses, drainage from oil wells has become a common problem in oil field development. To reduce drainage and improve recovery rates, chemical water sealant technology can be used to seal drainage layers. Generally, the plugging agent injected into water injection wells is called a cross-section adjustment agent, and the plugging agent injected into oil production wells is called a water sealant. Water sealant and cross-section adjustment technologies are effective means of improving reservoir heterogeneity, balanced displacement, and achieving stable oil production while maintaining low oil prices. In addition, heavy oil thermal mining, which mainly uses steam injection and steam flooding, is currently the main method used in heavy oil development around the world. During the entire decompression mining process, especially in the later stages of heavy oil development, limitations such as the lack of formation of geological barriers, permeability differences between layers, and development conditions can lead to problems such as low injection extraction ratios, low formation pressures, severe steam channeling and water submergence, and high difficulties in stable production. Therefore, channeling sealant must be injected to seal highly permeable underground layers and suppress steam channeling.

[0004] Conventional blocking agents can be broadly divided into jellies, gels, precipitates, granules, microspheres, foams, and microorganisms. Among them, the jelly type is the most widely used and most widely applied blocking agent in water-blocking and cross-section adjustment technology both in China and abroad. This type is mainly composed of polymers, and contains Cr 3+ , Al 3+ It is a three-dimensional network structure formed by using phenolic resin, phenol, and resorcinol as crosslinking agents.

[0005] However, due to the price fluctuations of fossil fuels and the increasing demand for biodegradability, irritation resistance, and ecotoxicity of oilfield chemicals during their application in oilfields, future developments in the bulk oilfield chemical manufacturing industry will primarily focus on resource efficiency, feedstock diversification, product value creation, and process decarbonization. Compared with traditional petrochemical refining and chemical synthesis methods, biomanufacturing boasts environmentally friendly, efficient, mild, low-carbon, and sustainable characteristics. It has already become a global strategic emerging industry, showing a rapid growth trend. Lignin is a complex natural polymer. In nature, it is the second most abundant natural organic compound after cellulose. Its phenylpropane groups are linked by ether (COC) or carbon-carbon (C-C) bonds to form a heterobranched three-dimensional network structure. Industrial lignin is readily available, inexpensive, and has a structure that varies depending on its origin and separation method. It contains active groups such as aromatic groups, phenolic hydroxyl groups, alcoholic hydroxyl groups, carbonyl groups, methoxy groups, carboxyl groups, and conjugated double bonds, and can undergo various chemical reactions such as oxidation, reduction, hydrolysis, alcoholysis, photolysis, acylation, sulfonation, alkylation, halogenation, nitration, condensation, and graft copolymerization.

[0006] On the other hand, existing polyacrylamide-chromium crosslinker or polyacrylamide-phenol crosslinker systems form a gel / jelly with a crosslinked network structure through dehydration condensation of polyacrylamide and crosslinker, which seals deep in the formation. This sealing system suffers from problems such as reduced stability due to polymer decomposition under high mineralization and temperature conditions in oil reservoirs, poor heat resistance, and insufficient colloidal strength, but there is room for improvement in its properties.

[0007] Existing lignin blocking technologies often use lignin directly, which has few cross-linking sites and low cross-linking activity. This results in high concentrations and large amounts of cross-linking agent required when preparing the blocking agent, making it costly and difficult to apply. Furthermore, the resulting blocking agents lack strength and poor heat resistance, limiting their blocking effect. Therefore, developing a blocking system that is inexpensive, has excellent product properties, and can maintain these properties even at high temperatures is of great significance for the sustainable development of water barrier, cross-section adjustment, and steam channeling technologies.

[0008] Summary of the Invention [Problem to be solved by the invention] The object of the present invention is to provide a plugging agent for oilfield oil extraction, and its preparation method and use, which solves the above-mentioned problems in the prior art. The plugging agent contains ligniamid, which is a modified lignin, and the modification significantly increases the number of cross-linking sites of lignin, improving the cross-linking activity of lignin, thereby reducing the amount of base resin and cross-linking agent used. The plugging agent can controllably gel over a wide range of oil reservoir temperatures, and has the characteristics of improved heat resistance, high strength, excellent injectability, high plugging strength, excellent heat resistance, and a wide range of applications, which effectively reduces the production cost of the plugging system, meets the requirements for properties, economy, and environmental protection in on-site application, and is highly practical.

[0009] [Means for solving the problem] In order to achieve the above object, a first aspect of the present invention provides a plugging agent for oil field production, which comprises ligniamide.

[0010] A second aspect of the present invention is A method for preparing a blocking agent is provided, which comprises the step of catalytically reacting ligniamide, an acrylamide polymer, a crosslinking agent, and a stabilizer in the presence of a solvent to obtain the blocking agent.

[0011] A third aspect of the present invention provides an occluding agent prepared by the above preparation method.

[0012] A fourth aspect of the present invention provides the use of the above-described plugging agent in oil field production.

[0013] [Effects of the Invention] According to the above technical proposal, the blocking agent, its preparation method and use according to the present invention can achieve the following beneficial effects:

[0014] The blocking agent of the present invention comprises ligniamid, which is a modified lignin. The modification significantly increases the number of cross-linking sites in the lignin, improving the cross-linking activity of the lignin and reducing the amount of base resin and cross-linking agent used. As a result, the blocking agent can controllably gel over a wide range of oil reservoir temperatures, and has the following characteristics: improved heat resistance, high strength, excellent injectability, high plugging strength, excellent heat resistance, and a wide range of applications. This effectively reduces the production cost of the blocking system, meets the performance, economy, and environmental protection requirements for on-site application, and is highly practical.

[0015] Furthermore, the plugging agent according to the present invention contains hydrolyzed ligniamide, an acrylamide polymer, a chromium crosslinker, a stabilizer, a pH adjuster, and water. The plugging agent can controllably gel (6 hours to 15 days) over a wide range of oil reservoir temperatures (30 to 120°C), maintains gelation for up to 132 days, has a dehydration rate of less than 5%, has a wide usable temperature range, and is strong. The long gelation time of the plugging agent makes it suitable for plugging high permeability zones in water injection wells, while the short gelation time makes it suitable for plugging single water layers in oil wells. The plugging agent has high viscosity, high plugging strength, a controllable gelation time, and a wide range of applications. It effectively reduces production costs, meets performance and economic requirements for on-site construction, and is highly practical, making it useful for water cutoff and cross-section adjustment in oil field production.

[0016] Furthermore, the plugging agent according to the present invention comprises hydrolyzed ligniamide, hydrolyzed acrylamide polymer, aluminum cross-linking agent, and stabilizer, and this plugging agent allows the use of biological materials instead of petrochemical raw materials. Furthermore, this water-blocking and cross-section adjustment system can controllably gel (16h-30d) over a wide range of reservoir temperatures (35-115°C), and has the characteristics of a plugging rate of more than 89.2%, a breakthrough pressure gradient of more than 1.25MPa / m, improved heat resistance, high strength, high system viscosity, high plugging strength, high applicable temperature, and low amounts of base resin and cross-linking agent, which effectively reduces the production cost of the water-blocking and cross-section adjustment system, meets the requirements for performance, economy, and environmental protection when applied in the field, and is highly practical.

[0017] Furthermore, the plugging agent of the present invention comprises ligniamide, an acrylamide polymer, polyethyleneimine, and a stabilizer, and this plugging agent allows the use of biological materials instead of petroleum-derived raw materials. Furthermore, this water-blocking and cross-section adjustment system can controllably delay gelation (3.5 to 9 days) under conditions of high reservoir temperatures (55 to 100°C), has high strength, and effectively reduces production costs.

[0018] Furthermore, the plugging agent of the present invention comprises ligniamide, an acrylamide polymer, a phenolic resin, and a stabilizer, and this plugging agent realizes the use of biological materials instead of petrochemical raw materials. The water-blocking and cross-section adjustment system can effectively block steam channels for a long period of time (50 to 120 days) at high oil reservoir temperatures (140 to 250°C), and has high strength. Therefore, the plugging agent of the present invention can effectively block high-permeability layers, adjust the difference in steam absorption between the high-permeability and low-permeability zones of the formation, and change the direction of injected steam movement, thereby reducing steam channeling, eliminating inter-well interference, increasing the volume of injected steam, and achieving the goals of improving periodic oil recovery and promoting efficient development of high-temperature oil reservoirs.

[0019] [Mode for Carrying Out the Invention] Preferred embodiments of the present invention will be described in more detail below. Preferred embodiments of the present invention will be described below, but it should be understood that the present invention should not be limited to the embodiments described herein and can be implemented in various forms. Rather, these embodiments are provided to make the present invention more complete and thorough, and to fully convey the scope of the present invention to those skilled in the art.

[0020] The endpoints of ranges and any values disclosed herein should be understood not to be limited to the exact range or value, but to include values close to those ranges or values. In the case of numerical ranges, the values between the endpoints of each range, the values between the endpoints of each range and the individual point values, and the values between the individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0021] A first aspect of the present invention provides an occluding agent comprising ligniamide.

[0022] Lignin is a complex natural polymer consisting of heterobranched three-dimensional networks of phenylpropane groups linked by ether (COC) or carbon-carbon (CC) bonds. In nature, lignin is the second most abundant natural organic substance after cellulose.

[0023] As a result of their research, the inventors of the present invention unexpectedly found that when lignin is modified by amination and acylation to obtain ligniamide, and this ligniamide is used as a blocking agent, the properties of the blocking agent are significantly improved. This is thought to be because the modification of lignin by amination and acylation increases the number of crosslinking sites on the lignin, thereby enhancing the crosslinking activity of the lignin.

[0024] In particular, when the modified ligniamide is blended with the acrylamide polymer in the plugging agent, the rigid molecular structure of the ligniamide and the flexible molecular structure of the polymer "complement each other's strengths and weaknesses," forming an interpenetrating network gel structure. When used in combination with other components of the plugging agent, it can be controllably gelled over a wide range of oil reservoir temperatures, and has characteristics such as excellent injectability, high plugging strength, excellent heat resistance, and a wide range of applications. It effectively reduces production costs and meets the performance, economical, and environmental requirements for on-site application, making it highly practical.

[0025] According to the present invention, the ligniamide is a hydrolyzed ligniamide.

[0026] According to the present invention, the method for preparing ligniamide comprises: (1) a step of reacting lignin with an organic amine under a first alkaline condition to form a lignin amine; (2) acylation of lignin amine with acyl chloride in a solution under a second alkaline condition to obtain the ligniamide; Optionally, the method includes a step (3) of hydrolyzing ligniamide with a hydrolysis agent to obtain hydrolyzed ligniamide.

[0027] In the present invention, the lignin, organic amine, and acyl chloride are all commercially available products, and preferably, the effective content of the lignin is 80 to 99.9%.

[0028] According to the present invention, the lignin may be any of various commonly used lignins, preferably at least one selected from alkaline lignin, enzymatically decomposed lignin, chlorinated lignin, steam-exploded lignin, lignosulfonate, and thiolignin, more preferably enzymatically decomposed lignin, which may be commercially available, for example, from Shandong Longli Biotechnology Co., Ltd.

[0029] According to the present invention, the organic amine may be any of various commonly used organic amines, and preferably, the organic amine is at least one selected from dimethylamine, ethylenediamine, trimethylamine, triethylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, putrescine, cadaverine, spermidine, and spermine.

[0030] More preferably, the organic amine is at least one selected from diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexaethyleneheptamine.

[0031] According to the present invention, the amount of the organic amine used may be selected from a wide range. In order to further improve the properties of the blocking agent, the mass ratio of the organic amine to the lignin may be preferably 0.05 to 4.5:1, for example, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 3:1, 3.5:1, 4:1, or 4.5:1.

[0032] According to the present invention, the pH value of the first alkaline condition may preferably be 10 to 11.5, for example, 10, 10.5, 11, or 11.5.

[0033] According to the present invention, the conditions for the amination reaction may vary over a wide range as long as the lignin can be modified by amination. To further improve the properties of the blocking agent, the temperature is preferably 60 to 75°C (e.g., 60°C, 65°C, 70°C, 75°C) and the time is preferably 1.5 to 4 hours (e.g., 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours).

[0034] In one preferred embodiment of the present invention, the amination reaction is carried out in the presence of an aldehyde, and the aldehyde is preferably a C1-C5 aldehyde, such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, or valeraldehyde, preferably formaldehyde, acetaldehyde, or propionaldehyde, more preferably formaldehyde. In this preferred embodiment, the properties of the prepared blocking agent can be further improved.

[0035] Preferably, the mass ratio of the aldehyde to the lignin may be 0.02 to 1.5:1, for example, 0.02:1, 0.05:1, 0.1:1, 0.3:1, 0.5:1, 0.7:1, 0.9:1, 1.1:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1, or 1.5:1.

[0036] According to the present invention, in step (2), the acyl chloride may be any of various commonly used acyl chlorides, and preferably, the acyl chloride is at least one selected from acetyl chloride, benzoyl chloride, oxalyl chloride, chloroacetyl chloride, trichloroacetyl chloride, fatty acid chloride, stearyl chloride, linoleyl chloride, oleic acid chloride, and palmitoyl chloride.

[0037] More preferably, the acyl chloride is at least one selected from oxalyl chloride, fatty acid chloride, stearyl chloride, linoleyl chloride, oleic acid chloride, and palmitoyl chloride.

[0038] According to the present invention, in step (2), the amount of the acyl chloride used may be selected within a wide range, and in order to further improve the properties of the blocking agent, preferably, the mass ratio of the acyl chloride to the lignin amine is 0.5 to 2.5:1 (e.g., 0.5:1, 0.8:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1).

[0039] According to the present invention, in step (2), the pH value of the second alkaline condition may preferably be 8 to 9.5, for example, 8, 8.5, 9, or 9.5.

[0040] According to the present invention, in step (2), the conditions for the acylation reaction may vary over a wide range, as long as the lignin is effectively acylated and modified to obtain ligniamide. To further improve the properties of the blocking agent, the temperature is preferably 55 to 65°C (e.g., 55°C, 60°C, 65°C) and the time is preferably 1 to 4 hours (e.g., 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours).

[0041] As a result of the inventors' research, it was found that ligniamide obtained under the amination conditions of 60-75°C for 1.5-4 hours and pH 10-11.5, and acylation conditions of 55-65°C for 1-4 hours and pH 8-9.5, can be used as a blocking agent with better effects.

[0042] According to the present invention, the hydrolyzing agent may be any substance capable of hydrolyzing the obtained ligniamide, preferably, the hydrolyzing agent is an alkali, more preferably, at least one selected from sodium hydroxide, sodium carbonate, sodium bicarbonate, and potassium hydroxide.

[0043] In the present invention, the amount of the hydrolyzing agent used may be selected within a wide range, and in order to further improve the properties of the blocking agent, the mass ratio of the hydrolyzing agent to the ligniamide is preferably 0.0001-0.8:1, more preferably 0.01-0.05:1, and the concentration of the hydrolyzing agent is 15-50 wt%.

[0044] In the present invention, the conditions for the hydrolysis reaction may vary over a wide range as long as the ligniamide after aminated and acylated is hydrolyzed. To further improve the properties of the blocking agent, the temperature is preferably 60 to 80°C (e.g., 60°C, 65°C, 70°C, 75°C, or 80°C) and the time is preferably 2 to 12 hours (e.g., 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours).

[0045] In one preferred embodiment of the present invention, the hydrolyzed ligniamide obtained under the amination conditions of a temperature of 60-75°C, a time of 1.5-4 hours, and a pH of 10-11.5, the acylation conditions of a temperature of 55-65°C, a time of 1-4 hours, and a pH of 8-9.5, and the hydrolysis conditions of a temperature of 60-80°C, a time of 2-12 hours, can be used as a blocking agent to obtain better effects.

[0046] In the present invention, the solution is preferably an aqueous solution.

[0047] In the present invention, the pH is adjusted by a method commonly used in the art, preferably by adding an alkaline substance, which may be a sodium hydroxide solution, a potassium hydroxide solution, a sodium carbonate solution, etc.

[0048] In one preferred embodiment of the present invention, the method for preparing ligniamide comprises the steps of: Step (1) of preparing a lignin aqueous solution under a first alkaline condition, and then adding an organic amine to the aqueous solution while stirring to carry out an amination reaction to obtain a lignin amine; (2) preparing a lignin amine aqueous solution under second alkaline conditions, and then adding acyl chloride to the solution while stirring to carry out an acylation reaction to obtain ligniamide; Optionally, the method includes a step (3) of hydrolyzing ligniamide with a hydrolysis agent to obtain the hydrolyzed ligniamide.

[0049] Preferably, the concentration of lignin in the lignin aqueous solution may be 3 to 50 wt%, for example, 3 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%.

[0050] Preferably, the organic amine is added dropwise to the aqueous lignin solution.

[0051] Preferably, the concentration of lignin amine in the aqueous lignin amine solution is 3 to 30 wt %.

[0052] Preferably, the acyl chloride is added dropwise to the aqueous lignin amine solution.

[0053] Preferably, the lignin amine is obtained by adjusting the pH after the amination reaction to precipitate the product, which is then washed and dried to obtain the intermediate product, lignin amine.

[0054] In a particularly preferred embodiment of the present invention, the ligniamide is prepared by the following method:

[0055] (1) Lignin and alkali are dissolved in water and stirred to prepare a lignin solution.

[0056] (2) Next, an organic amine is added to adjust the pH, and formaldehyde is added while stirring. The mixture is heated to reflux and reacted. After the reaction is complete, the pH is adjusted to approximately neutral, and the product is precipitated, washed, and dried to obtain the intermediate product, lignin amine.

[0057] (3) The intermediate product, lignin amine, is dissolved in water, the pH is adjusted, acyl chloride is added while stirring, the reaction is continued, and then the mixture is suction filtered, washed, dried, and pulverized to obtain ligniamide.

[0058] (4) Optionally, ligniamide and the hydrolysis solution are mixed to carry out the hydrolysis reaction, and then the mixture is dried and pulverized to obtain the hydrolyzed ligniamide product.

[0059] Preferably, the ligniamide is prepared by the following method.

[0060] (1) At room temperature, lignin and NaOH are dissolved in water to prepare a lignin solution having a lignin concentration of 3 to 50 wt % and a NaOH concentration of 0.001 to 8 wt %.

[0061] (2) Next, an organic amine is added dropwise, the pH is adjusted to 10-11.5, formaldehyde is added dropwise while stirring, and the mixture is heated to reflux to cause a reaction. After the reaction is complete, the pH is adjusted to approximately neutral, and the product is precipitated, washed, and dried to obtain the intermediate product, lignin amine. The mass ratio of the organic amine, formaldehyde, and lignin used is 0.05-4.5:0.02-1.5:1, the reaction temperature is 60-75°C, and the reaction time is 1.5-4 hours.

[0062] (3) The intermediate product, lignin amine, is dissolved in water to a concentration of 3 to 30 wt%, the pH is adjusted to 8 to 9.5, and while stirring, acyl chloride is added dropwise so that the mass ratio of acyl chloride to lignin amine is 0.5 to 2.5:1. The temperature is then raised to 55 to 65°C and the reaction is continued for 1 to 4 hours. After the reaction is complete, the mixture is suction filtered, washed, dried, and pulverized to obtain lignin amide.

[0063] (4) Optionally, ligniamide and sodium hydroxide solution are blended in a predetermined ratio, hydrolyzed, sealed, and reacted at 60-80°C for 2-12 hours, then dried and pulverized to obtain a hydrolyzed ligniamide product. The mass ratio of the hydrolyzing agent to the ligniamide is 0.0001-0.8:1, and the concentration of the hydrolyzing agent is 15-50 wt%.

[0064] According to the present invention, the occluding agent further comprises an acrylamide-based polymer, a crosslinking agent, and a stabilizer.

[0065] In the present invention, the acrylamide polymer includes an acrylamide homopolymer and / or an acrylamide copolymer.

[0066] In the present invention, the inventors have conducted research and found that the properties of the occlusive agent can be improved by preparing a jelly system using ligniamide or hydrolyzed ligniamide in combination with an acrylamide polymer, a crosslinker, and a stabilizer.

[0067] In the present invention, there is no particular limitation on the content of each component. However, in order to obtain a better effect, the content of the ligniamide is preferably 0.1 to 5.5 wt% (e.g., 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, preferably 0.4 to 2 wt%) based on the total weight of the blocking agent, and the content of the acrylamide is preferably 0.4 to 2 wt% based on the total weight of the blocking agent. The content of the crosslinking polymer is 0.01 to 3.5 wt% (for example, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, preferably 0.01 to 1.5 wt%). The content of the crosslinker is 0.05 to 4.5 wt% (e.g., 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, 10.0 wt%, 11.0 wt%, 12.0 wt%, 13.0 wt%, 14.0 wt%, 15.0 wt%, 16.0 wt%, 17.0 wt%, 18.0 wt%, 19.0 wt%, 20.0 wt%, 21.0 wt%, 22.0 wt%, 23.0 wt%, 24.0 wt%, 25.0 wt%, 26.0 wt%, 27.0 wt%, 28.0 wt%, 29.0 wt%, 30.0 wt%, 31.0 wt%, 32.0 wt%, 33.0 wt%, 34.0 wt%, 35.0 wt%, 36.0 wt%, 37.0 wt%, 38.0 wt%, 39.0 wt%, 40.0 wt%, 41.0 wt%, 42.0 wt%, 43.0 wt%, 44.0 t%, 4.5 wt%, preferably 0.05 to 2 wt%), and the content of the stabilizer is 0.01 to 2.5 wt% (for example, 0.01 wt%, 0.03 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.3 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, preferably 0.02 to 1 wt%).

[0068] According to the present invention, the acrylamide-based polymer may be any of various commonly used acrylamide-based polymers. Preferably, in order to further improve the properties of the prepared blocking agent, the acrylamide-based polymer is at least one selected from an anionic acrylamide-based polymer, a cationic polyacrylamide, a nonionic acrylamide-based polymer, and an amphoteric acrylamide-based polymer.

[0069] More preferably, the acrylamide polymer is at least one selected from an anionic acrylamide polymer, a nonionic acrylamide polymer, and an amphoteric polyacrylamide polymer.

[0070] According to the present invention, the weight average molecular weight of the acrylamide polymer is 500 to 3,500, preferably 6 to 30,000,000, more preferably 15 to 25,000,000, and even more preferably 18 to 22,000,000.

[0071] According to the present invention, the solid content of the acrylamide polymer is 80% by weight or more, preferably 85% by weight or more.

[0072] In one particular embodiment of the present invention, the acrylamide-based polymer is a hydrolyzed acrylamide-based polymer, and in particular, the acrylamide-based polymer is a hydrolyzed anionic acrylamide-based polymer.

[0073] In the present invention, the hydrolyzed acrylamide polymer may be any hydrolyzed acrylamide polymer, and preferably, the hydrolysis degree of the hydrolyzed acrylamide polymer is 15-30%, in order to further improve the properties of the prepared blocking agent. The hydrolyzed acrylamide polymer may be commercially available, for example, from Shandong Baomo Biochemical Co., Ltd.

[0074] In the present invention, the weight average molecular weight of the hydrolyzed acrylamide polymer is preferably 8 to 30 million.

[0075] According to the present invention, the crosslinking agent is at least one selected from an aluminum crosslinking agent, polyethyleneimine, a phenolic resin, and a chromium crosslinking agent.

[0076] According to the present invention, the crosslinking agent is preferably an aluminum crosslinking agent, and is at least one selected from aluminum citrate and polyaluminum. In the present invention, the aluminum citrate may be commercially available, for example, purchased from Ningbo Chemical Raw Materials Co., Ltd.

[0077] The polyaluminum is ACH, which is generally called aluminum chlorohydrate and is also called polyaluminum or aluminum chlorohydrate in Chinese, and has the molecular formula Al2(OH)5Cl·2H2O.

[0078] According to the present invention, the polyethyleneimine may have a weight-average molecular weight of 3,000 to 100,000 and an effective content of about 15 to 50 wt %, and the polyethyleneimine may be commercially available, for example, from Aladdin (Shanghai).

[0079] According to the present invention, the phenolic resin may be any of various commonly used phenolic resins, and preferably, the phenolic resin has a pH value greater than 11 and a solid content greater than 38 wt%.

[0080] According to the present invention, the chromium crosslinking agent is at least one selected from sodium dichromate, ammonium dichromate, and potassium dichromate.

[0081] According to the present invention, the stabilizer may be commercially available, and preferably, the stabilizer is at least one selected from sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium dithionite, m-phenylenediamine, isoascorbic acid, and thiourea.

[0082] According to the present invention, the blocking agent further comprises a pH adjuster and water. In one preferred embodiment of the present invention, the blocking agent comprises ligniamide, an acrylamide polymer, a crosslinking agent, a stabilizer, a pH adjuster, and water. However, depending on the purity of the raw materials used, some impurities are inevitably present in each raw material. Therefore, it is clear that the water-blocking and cross-section adjusting system is composed of ligniamide, an acrylamide polymer, a crosslinking agent, a stabilizer, a pH adjuster, water, and the impurities originally contained in each raw material.

[0083] In the present invention, the content of the pH adjuster is 0.01 to 0.45 wt %, preferably 0.01 to 0.2 wt %, based on the total weight of the blocking agent.

[0084] According to the present invention, the pH adjuster may be an acid or alkaline substance commonly used for pH adjustment in the prior art, and preferably, the pH adjuster is at least one selected from dilute hydrochloric acid, dilute sulfuric acid, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium acetate, and aqueous ammonia.

[0085] In the present invention, the water contained in the blocking agent is not particularly limited, and may be river water, lake water, atmospheric water, seawater, groundwater, artificial water, or water produced from an oil field, but is preferably water with a mineralization level of less than 100,000 mg / L, preferably less than 30,000 mg / L, and a divalent ion content of less than 3,000 mg / L.

[0086] SPECIFIC EMBODIMENT I In the present invention, the blocking agent comprises hydrolyzed ligniamide, an acrylamide-based polymer, a chromium crosslinking agent, a stabilizer, a pH adjuster, and water.

[0087] Through their research, the inventors of the present invention unexpectedly discovered that when lignin is subjected to amination, acylation, and hydrolysis to obtain hydrolyzed ligniamide, the amination and acylation of lignin increases the number of cross-linking sites in the lignin, improving the cross-linking activity of the lignin and, as a result, improving the properties of the blocking agent. The rigid molecular structure of the hydrolyzed ligniamide and the flexible molecular structure of the polymer "complement each other's strengths and weaknesses," forming an interpenetrating network gel structure. When used in combination with other components of the plugging agent, it can controllably gel (6 hours to 15 days) over a wide range of oil reservoir temperatures (30 to 120°C), maintain gelation for up to 132 days, and have a dehydration rate of less than 5%. It has a wide operating temperature range and high strength. With a long gelation time, it can be used to plug the high permeability zone of a water injection well, and with a short gelation time, it can be used to plug a single water layer of an oil well. This plugging agent has the characteristics of high viscosity, high plugging strength, controllable gelation time, and a wide range of applications, which effectively reduces production costs and meets the performance and economic requirements for on-site construction, making it highly practical.

[0088] In the present invention, the preparation and types of the hydrolyzed ligniamide, acrylamide polymer, chromium crosslinker, stabilizer, and pH adjuster have been described in detail in the first embodiment above, so to avoid duplication, they will not be described in detail here.

[0089] In the present invention, the blocking agent contains, based on the total weight of the blocking agent, 0.1 to 4.5 wt% of hydrolyzed ligniamide, 0.02 to 1.2 wt% of an acrylamide polymer, 0.02 to 1.2 wt% of a chromium crosslinker, 0.03 to 1.8 wt% of a stabilizer, 0.01 to 0.45 wt% of a pH adjuster, and 90.85 to 99.82 wt% of water.

[0090] To obtain even better effects, specifically to enable controllable crosslinking at a higher gelling temperature of the blocking agent and further increase the jelly strength, the blocking agent preferably contains, based on the total weight of the blocking agent, 0.5 to 2 wt% hydrolyzed ligniamide, 0.05 to 0.5 wt% acrylamide polymer, 0.05 to 0.4 wt% chromium crosslinker, 0.1 to 0.6 wt% stabilizer, 0.01 to 0.2 wt% pH adjuster, and 96.3 to 99.29 wt% water.

[0091] SPECIFIC EMBODIMENT II In the present invention, the blocking agent comprises hydrolyzed ligniamide, hydrolyzed acrylamide polymer, aluminum crosslinker, and stabilizer.

[0092] The inventors of the present invention have unexpectedly found that by amminating, acylating, and hydrolyzing lignin to obtain hydrolyzed ligniamide, and then combining this hydrolyzed ligniamide with hydrolyzed polyacrylamide, an aluminum-based crosslinker, and additives to prepare an aluminum jelly system, they can improve the properties of a plugging agent. The resulting plugging agent can controllably gel over a wide range of reservoir temperatures (35-115°C) (16 hours to 30 days, preferably 18 hours to 8 days), achieve a plugging rate of greater than 89.2%, preferably 98.3%, a breakthrough pressure gradient of greater than 1.25 MPa / m, preferably greater than 4.5 MPa / m, improved heat resistance, and high strength. The plugging agent also has the characteristics of high system viscosity, high plugging strength, and high operating temperature. This effectively reduces the production costs of water-blocking and cross-section-adjusting systems, meets the performance, economy, and environmental requirements for on-site application, and is highly practical.

[0093] In the present invention, the preparation and types of the hydrolyzed ligniamide, hydrolyzed acrylamide polymer, crosslinking agent, and stabilizer have been described in detail in the first embodiment above, so to avoid duplication, they will not be described in detail here.

[0094] Preferably, to obtain even better effects, for example, to enable controllable crosslinking at a higher gelling temperature of the occluding agent and further increase the jelly strength, the content of the hydrolyzed ligniamide is 0.1 to 4.5 wt% (e.g., 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4.5 wt%, 5.5 wt%, 6.5 wt%, 7.5 wt%, 8.5 wt%, 9.5 wt%, 10.5 wt%, 11.5 wt%, 12.5 wt%, 13.5 wt%, 14.5 wt%, 15.5 wt%, 16.5 wt%, 17.5 wt%, 18.5 wt%, 19.5 wt%, 20.5 wt%, 21.5 wt%, 22.5 wt%, 23.5 wt%, 24.5 wt%, 25.5 wt%, 26.5 wt%, 27.5 wt%, 28.5 wt%, 29.5 wt%, 30.5 wt%, 31.5 wt%, 32.5 wt%, 33.5 wt%, 34.5 wt%, 35.5 wt%, 36.5 wt%, 37.5 wt%, 38.5 wt%, 39 ... 5 wt%, 4 wt%, 4.5 wt%, preferably 0.4 to 2 wt%, and the content of the hydrolyzed polyacrylamide is 0.01 to 1.5 wt% (for example, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%). , 1.3 wt%, 1.4 wt%, 1.5 wt%, preferably 0.01 to 0.5 wt%, and the content of the crosslinking agent is 0.05 to 2 wt% (for example, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, t%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%, preferably 0.2 to 1.2wt%, and the content of the stabilizer is 0.03 to 0.6wt% (for example, 0.03wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, preferably 0.05 to 0.4wt%).

[0095] SPECIFIC EMBODIMENT III In the present invention, the blocking agent includes ligniamide, an acrylamide-based polymer, polyethyleneimine, and a stabilizer.

[0096] The inventors of the present invention have unexpectedly found that by amminating and acylating lignin to obtain ligniamide, and then combining this ligniamide with an acrylamide polymer, polyethyleneimine as a crosslinker, and a stabilizer to prepare a jelly, the properties of the blocking agent are improved, i.e., the gelation delay controllability and colloid strength are improved. The blocking agent thus prepared can controllably delay gelation (3.5-9 days) at a high gelation temperature (55-100°C), has high strength, and effectively reduces production costs.

[0097] In the present invention, the preparation and types of the ligniamide, acrylamide polymer, polyethyleneimine as a crosslinking agent, and stabilizer have been described in detail in the first embodiment, and therefore will not be described in detail here to avoid duplication.

[0098] In the present invention, preferably, in order to obtain even better effects, for example, to enable the cross-section modifier to controllably delay cross-linking and to improve the strength of the jelly, the content of the ligniamid is preferably 0.1 to 4.5 wt% (e.g., 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, preferably 0.4 to 2 wt%) based on the total weight of the occluding agent, and the content of the polyacrylamide is 0.1 to 3.5 wt% (e.g., 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1. 3 wt%, 1.4 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, preferably 0.1 to 1.5 wt%, and the content of the crosslinking agent is 0.05 to 1 wt% (for example, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, preferably 0.1 to 1.5 wt%). The content of the stabilizer is preferably 0.2 to 0.8 wt% (for example, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.3 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, preferably 0.1 to 1 wt%).

[0099] SPECIFIC EMBODIMENT IV In the present invention, the blocking agent includes ligniamide, an acrylamide-based polymer, a phenolic resin, and a stabilizer.

[0100] As a result of their research, the inventors of the present invention unexpectedly found that lignin was modified by amination and acylation to obtain ligniamide, which was then combined with an acrylamide polymer, a phenolic resin crosslinker, and a stabilizer to prepare a jelly system. This ligniamide was then able to effectively block steam channels for a long period of time (50-120 days) at high reservoir temperatures (140-250°C), with high strength. Therefore, the blocking agent can effectively block high-permeability layers, adjust the difference in steam absorption between the high-permeability and low-permeability layers of the formation, and redirect the flow of injected steam. This reduces steam channeling, eliminates inter-well interference, increases the volume of injected steam, and achieves the goals of improving periodic oil recovery and efficiently exploiting high-temperature reservoirs.

[0101] In the present invention, the preparation and types of the ligniamide, acrylamide polymer, crosslinker phenolic resin, and stabilizer have been described in detail in the first embodiment above, so to avoid duplication, they will not be described in detail here.

[0102] In the present invention, in order to obtain a better effect, for example, to further enhance the effect of the blocking agent and further increase the strength of the jelly, it is more preferable that the content of the ligniamide is 0.1 to 5.5 wt% (for example, 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 ...9 wt%, 59 w wt%, 5.5 wt%, preferably 0.4 to 2 wt%, and the content of the polyacrylamide is 0.01 to 1.5 wt% (for example, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1. 5 wt%, preferably 0.1 to 0.5 wt%, and the content of the crosslinking agent phenolic resin is 0.05 to 4.5 wt% (for example, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4 0.5wt%, preferably 0.2 to 2.0wt%), and the content of the stabilizer is 0.01 to 2wt% (e.g., 0.01wt%, 0.03wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.8wt%, 1wt%, 1.3wt%, 1.5wt%, 1.8wt%, 2wt%, preferably 0.02 to 0.5wt%).

[0103] A second aspect of the present invention is A method for preparing a blocking agent is provided, which comprises the step of catalytically reacting ligniamide, an acrylamide polymer, a crosslinking agent, and a stabilizer in the presence of a solvent to obtain the blocking agent.

[0104] In the present invention, the preparation, types and amounts of the ligniamide, acrylamide polymer, crosslinking agent and stabilizer have been described in detail in the first embodiment above, and therefore will not be described in detail here to avoid duplication.

[0105] In one preferred embodiment according to the present invention, the method for preparing the blocking agent comprises: Step (1) of adding ligniamide and acrylamide polymers to water with stirring and dissolving them uniformly; and (2) adding a crosslinking agent, a stabilizer, and a pH adjuster to effect a catalytic reaction to obtain the blocking agent.

[0106] In the present invention, the order in which the crosslinking agent, stabilizer, and pH adjuster are added is not particularly limited as long as a uniformly mixed blocking agent can be obtained.

[0107] In the present invention, the amount of the pH adjuster used is preferably such that the pH value of the reaction system is 6 to 8, more preferably such that the pH value of the reaction system is 6 to 8. 3+ The pH may be, for example, 5.5 to 6.5, so as not to cause precipitation.

[0108] In the present invention, the temperature and time of the contact reaction are preferably not particularly limited as long as the materials can be mixed uniformly.

[0109] A third aspect of the present invention provides an occluding agent prepared by the above preparation method.

[0110] A fourth aspect of the present invention provides the use of the above-described plugging agent in oil field production.

[0111] The present invention will be described in detail below with reference to examples.

[0112] The complex viscosity is tested with a rotational rheometer (RS6000, purchased from Thermo Fisher Scientific).

[0113] The gel strength is tested by the breakthrough vacuum method (GL-802A micro benchtop vacuum pump, purchased from Haimen Qilin Bell Instrument Manufacturing Co., Ltd.).

[0114] Occlusion Rate Test: A simulated rock core (25mm diameter, 200mm long) was prepared, and vacuum suction and water saturation treatment were performed on the simulated rock core. First, a 10% NaCl solution was injected into the rock core at a constant flow rate, and the permeability (k0) before the rock core was plugged was measured. Next, a plugging agent solution according to the evaluation formula was injected in the forward or reverse direction, and both ends of the rock core were plugged with plugs. The rock core was then left to stand in a thermostatic chamber at a specified temperature for a specified number of days. Finally, a 10wt% NaCl solution was injected to measure the permeability (k') and breakthrough pressure after the rock core was plugged. The plugging rate was used as a parameter that represents the plugging effect of the plugging agent, and the formula for calculating the plugging rate was:

[0115]

number

[0116] where k0 is the pre-blockage permeability, μm 2 ) and k' is the post-occlusion permeability (μm 2 )

[0117] The breakthrough pressure gradient is calculated from the measured breakthrough pressure and core size.

[0118] The lignin was enzymatically decomposed lignin purchased from Shandong Longli Biotechnology Co., Ltd., with a solid content of 94.8 wt%.

[0119] The cross-linking agent, aluminum citrate, was purchased from Ningbo Chemical Raw Materials Co., Ltd., and the aluminum concentration was 2000 mg / kg.

[0120] Diethylenetriamine, tetraethylenepentamine, oleic acid chloride, and palmitoyl chloride are purchased from Bailingwei Technology Co., Ltd.

[0121] Acrylamide polymer I, an anionic acrylamide polymer, was purchased from Shandong Baomo Biochemical Co., Ltd., with a solid content of 90 wt%.

[0122] Acrylamide polymer II, an anionic acrylamide polymer, was purchased from Shandong Baomo Biochemical Co., Ltd., with a solid content of 89 wt%.

[0123] Hydrolyzed acrylamide polymer III, hydrolyzed anionic acrylamide polymer, was purchased from Shandong Baomo Biochemical Co., Ltd., with a weight-average molecular weight of 15 million and a hydrolysis degree of 25%.

[0124] Hydrolyzed acrylamide polymer IV, hydrolyzed anionic acrylamide polymer, was purchased from Shandong Baomo Biochemical Co., Ltd., with a weight-average molecular weight of 10 million and a hydrolysis degree of 23%.

[0125] Hydrolyzed acrylamide polymer V, hydrolyzed anionic acrylamide polymer, was purchased from Shandong Baomo Biochemical Co., Ltd., with a weight-average molecular weight of 20 million and a hydrolysis degree of 20%.

[0126] Hydrolyzed acrylamide polymer VI, hydrolyzed anionic acrylamide polymer, was purchased from Shandong Baomo Biochemical Co., Ltd., with a weight-average molecular weight of 8 million and a hydrolysis degree of 25%.

[0127] Acrylamide polymer VII, a nonionic acrylamide polymer, was purchased from Shandong Baomo Biochemical Co., Ltd., with a solid content of 90 wt% and a weight-average molecular weight of 15.5 million.

[0128] Acrylamide polymer VIII, a nonionic acrylamide polymer, was prepared according to the method of Example 1 of CN108017754A, and had a solids content of 89 wt% and a weight-average molecular weight of 21 million.

[0129] Acrylamide polymer IX, a nonionic acrylamide polymer, was prepared according to the method of Example 2 of CN108017754A, and has a solids content of 91 wt% and a weight-average molecular weight of 19.8 million.

[0130] The phenolic resin was purchased from Dongshida Oil Clothing Technology Service Co., Ltd., and had a pH value greater than 11 and a solid content greater than 38 wt%.

[0131] All other ingredients not specified are common, commercially available products.

[0132] SPECIFIC EMBODIMENT I Preparation Example 1 Preparation of hydrolyzed ligniamide L1 (1) At room temperature, 10 g of lignin and 1.67 g of NaOH were dissolved in water to prepare a 15 wt% aqueous lignin solution.

[0133] (2) Next, 12 g of diethylenetriamine was added dropwise to the lignin aqueous solution, the pH was adjusted to 10.5, 14.4 g of formaldehyde was added dropwise while stirring, and the mixture was heated to reflux, and the first contact reaction was carried out at 70°C for 2.5 hours. After the reaction was completed, the pH was adjusted to approximately neutral, and the product was precipitated, washed, and dried to obtain the intermediate product, lignin amine.

[0134] (3) 6 g of the intermediate product, lignin amine, was dissolved in water, the pH was adjusted to 8.5, and 7.65 g of oleic acid chloride was added dropwise while stirring. The temperature was then raised to 60°C, and the second contact reaction was carried out for 3 hours. After the reaction was completed, the mixture was suction filtered, washed, dried, and pulverized to obtain ligninamide.

[0135] (4) 6.5 g of ligniamide was blended with 1.75 g of 30 wt % NaOH solution, sealed, and subjected to the third contact reaction (hydrolysis) at 80°C for 8 hours. After the reaction was completed, the mixture was dried and pulverized to obtain hydrolyzed ligniamide product L1.

[0136] Preparation Example 2 Preparation of hydrolyzed ligniamide L2 A hydrolyzed ligniamide product L2 was obtained in the same manner as in Preparation Example 1, except that 12 g of diethylenetriamine was replaced with 21.6 g of tetraethylenepentamine and 7.65 g of oleic acid chloride was replaced with 7.05 g of palmitoyl chloride.

[0137] Example 1 This example illustrates an occlusive agent according to the present invention.

[0138] 9.2 g of hydrolyzed ligniamide L1 and 4.5 g of acrylamide polymer I were dissolved in 1 L of water with a mineralization level of 6000 mg / L and stirred at 500 r / min until uniformly dissolved. 2.56 g of thiourea, 0.14 g of aqueous ammonia, and 1.54 g of sodium dichromate were then added and stirred uniformly to obtain a blocking agent. The gelation temperature, gelation initiation time, viscosity after crosslinking, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0139] Example 2 This example illustrates an occlusive agent according to the present invention.

[0140] 12.1 g of hydrolyzed ligniamide L2 and 3.8 g of acrylamide polymer I were dissolved in 1 L of water with a mineralization level of 6500 mg / L and stirred at 500 r / min until uniformly dissolved. 2.54 g of sodium dithionite, 0.23 g of aqueous ammonia, and 1.81 g of sodium dichromate were then added and stirred uniformly to obtain a blocking agent. The gelation temperature, gelation initiation time, multiple viscosity after crosslinking, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0141] Example 3 This example illustrates an occlusive agent according to the present invention.

[0142] 6.3 g of hydrolyzed ligniamide L1 and 1.8 g of acrylamide polymer II were dissolved in 1 L of water with a mineralization level of 1500 mg / L and stirred at 500 rpm until uniformly dissolved. 2.5 g of sodium bisulfite, 0.16 g of dilute hydrochloric acid, and 2.02 g of sodium dichromate were then added and stirred uniformly to obtain a blocking agent. The gelation temperature, gelation initiation time, viscosity at the crosslinking reaction, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0143] Example 4 This example illustrates an occlusive agent according to the present invention.

[0144] 8.8 g of hydrolyzed ligniamide L2 and 3.2 g of acrylamide polymer II were dissolved in 1 L of water with a mineralization level of 2500 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 1.89 g of sodium thiosulfate, 0.32 g of aqueous ammonia, and 1.74 g of sodium dichromate were added and stirred uniformly to obtain a blocking agent. The gelation temperature, gelation initiation time, multiple viscosity after crosslinking, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0145] Comparative Example 1 This comparative example illustrates a comparative occlusive agent.

[0146] A blocking agent was obtained by the same experiment as in Example 1, except that the total mass of hydrolyzed ligniamide L1 and acrylamide polymer I was changed to acrylamide polymer I equal to the total mass of both. The gelation temperature, gelation initiation time, multiple viscosity after the crosslinking reaction, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0147] Comparative Example 2 This comparative example illustrates a comparative occlusive agent.

[0148] A blocking agent was obtained by the same experiment as in Example 2, except that the total mass of hydrolyzed ligniamide L2 and acrylamide polymer I was changed to acrylamide polymer I equal to the total mass of both. The gelation temperature, gelation initiation time, multiple viscosity after the crosslinking reaction, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0149] Comparative Example 3 This comparative example illustrates a comparative occlusive agent.

[0150] A blocking agent was obtained by the same experiment as in Example 3, except that the hydrolyzed ligniamide L1 and acrylamide polymer II were replaced with acrylamide polymer II equal in mass to the total mass of both. The gelation temperature, gelation initiation time, multiple viscosity after the crosslinking reaction, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0151] Comparative Example 4 This comparative example illustrates a comparative occlusive agent.

[0152] A blocking agent was obtained by the same experiment as in Example 4, except that the total mass of hydrolyzed ligniamide L2 and acrylamide polymer II was changed to acrylamide polymer II equal to the total mass of both. The gelation temperature, gelation initiation time, multiple viscosity after the crosslinking reaction, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0153] Comparative Example 5 This comparative example illustrates a comparative occlusive agent.

[0154] A blocking agent was obtained by the same procedure as in Example 1, except that the hydrolyzed ligninamide L1 was replaced with the same mass of lignin. The gelation temperature, gelation initiation time, multiple viscosity after the crosslinking reaction, gel retention time at the gelation temperature, and dehydration rate of the blocking agent are shown in Table 1.

[0155] [Table 1]

[0156] A comparison of the Examples and Comparative Examples clearly shows that the present invention increases the cross-linking sites of lignin by aminating, acylating, and hydrolyzing lignin, thereby improving the cross-linking activity of lignin and resulting in improved properties of the water-blocking and cross-section-conditioning agent. The plugging agent of the present invention can controllably gel (6 hours to 15 days) over a wide range of oil reservoir temperatures (30-120°C), maintains gelation for up to 132 days, has a dehydration rate of less than 5%, has a wide operating temperature range, and is strong. Its long gelation time makes it suitable for plugging high permeability zones in water injection wells, while its short gelation time makes it suitable for plugging single water layers in oil wells. The plugging agent has high viscosity, high plugging strength, a controllable gelation time, and a wide range of applications. It effectively reduces production costs, meets performance and economic requirements for on-site application, and is highly practical.

[0157] SPECIFIC EMBODIMENT II Preparation Example 3 This preparation illustrates the preparation of hydrolyzed ligniamide L3.

[0158] (1) At room temperature, 10 g of lignin and 1.62 g of NaOH were dissolved in water to prepare a 15 wt% lignin solution.

[0159] (2) Next, 12.5 g of diethylenetriamine was added dropwise, the pH was adjusted to 10.5, and 14.1 g of formaldehyde was added dropwise while stirring. The mixture was heated to reflux and reacted for 2.5 hours. After the reaction was completed, the pH was adjusted to approximately neutral, and the product was precipitated, washed, and dried to obtain the intermediate product, lignin amine.

[0160] (3) 6 g of lignin amine was dissolved in water, the pH was adjusted to 8.5, and 7.53 g of oleic acid chloride was added dropwise while stirring. The temperature was then raised to 60°C and the reaction was continued for 3 hours. After the reaction was completed, the mixture was suction filtered, washed, dried and pulverized to obtain lignin amide.

[0161] (4) 6.5 g of ligniamide was added to water to swell it, and then blended with 0.21 g of 30 wt % NaOH solution. The mixture was sealed and reacted at 60°C for 8 hours. After the reaction was completed, the mixture was dried and pulverized to obtain hydrolyzed ligniamide product L3.

[0162] Preparation Example 4 This preparation illustrates the preparation of hydrolyzed ligniamide L4.

[0163] Hydrolyzed ligniamide product L4 was obtained according to the method of Preparation Example 3, except that 12.5 g of diethylenetriamine was replaced with 19.4 g of tetraethylenepentamine and 7.53 g of oleic acid chloride was replaced with 6.8 g of palmitoyl chloride.

[0164] Preparation Example 5 This preparation illustrates the preparation of hydrolyzed ligniamide L5.

[0165] The method of Preparation 3 was followed, except that no formaldehyde was added in step (2), to give hydrolyzed ligniamide product L5.

[0166] Example 5 This example illustrates an occlusive agent according to the present invention.

[0167] 12.1 g of hydrolyzed ligniamide L3 and 1.6 g of hydrolyzed acrylamide polymer III were dissolved in water with a mineralization level of 13,000 mg / L (divalent ion content less than 3,000 mg / L) and stirred at 500 r / min until uniformly dissolved. Next, 1.11 g of sodium bisulfite and 2 g of aluminum citrate were added to adjust the pH of the system to prevent Al3+ precipitation. The total mass of the system was adjusted to 1 kg, and the mixture was stirred uniformly to obtain a blocking agent. The gelation temperature, gelation onset time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0168] Example 6 This example illustrates an occlusive agent according to the present invention.

[0169] 4 g of hydrolyzed ligniamide L3 and 5 g of hydrolyzed acrylamide polymer IV were dissolved in water with a mineralization level of 15,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 4 g of sodium bisulfite and 8 g of aluminum citrate were added, and the pH of the system was adjusted to prevent Al3+ precipitation. The total mass of the system was adjusted to 1 kg, and the mixture was mixed uniformly to obtain a blocking agent. The gelation temperature, gelation onset time, and post-crosslinking viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 2.

[0170] Example 7 This example illustrates an occlusive agent according to the present invention.

[0171] 20 g of hydrolyzed ligniamide L3 and 0.1 g of hydrolyzed acrylamide polymer V were dissolved in water with a mineralization level of 18,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 0.5 g of sodium bisulfite and 12 g of aluminum citrate were added, and the pH of the system was adjusted to prevent Al3+ precipitation. The total weight of the system was adjusted to 1 kg to obtain a blocking agent. The gelation temperature, gelation onset time, and post-crosslinking viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 2.

[0172] Example 8 This example illustrates an occlusive agent according to the present invention.

[0173] A blocking agent was prepared according to the method of Example 5, except that hydrolyzed acrylamide polymer III was replaced with hydrolyzed acrylamide polymer VI. The gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0174] Example 9 This example illustrates an occlusive agent according to the present invention.

[0175] A blocking agent was prepared according to the method of Example 5, except that hydrolyzed ligniamide L3 was replaced with hydrolyzed ligniamide L4. The gelation temperature, gelation onset time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0176] Example 10 This example illustrates an occlusive agent according to the present invention.

[0177] A blocking agent was prepared according to the method of Example 5, except that hydrolyzed ligniamide L3 was replaced with hydrolyzed ligniamide L5. The gelation temperature, gelation onset time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0178] Example 11 This example illustrates an occlusive agent according to the present invention.

[0179] 12.4 g of hydrolyzed ligniamide L4 and 1.9 g of hydrolyzed acrylamide polymer III were dissolved in water with a mineralization level of 18,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 1.39 g of thiourea and 1.62 g of aluminum citrate were added, and the pH of the system was adjusted to prevent Al3+ precipitation. The total mass of the system was adjusted to 1 kg to obtain a blocking agent. The gelation temperature, gelation onset time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0180] Example 12 This example illustrates an occlusive agent according to the present invention.

[0181] 10.9 g of hydrolyzed ligniamide L3 and 2.4 g of hydrolyzed acrylamide polymer III were dissolved in water with a mineralization level of 10,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 1.45 g of thiourea and 1.1 g of aluminum citrate were added, and the pH of the system was adjusted to prevent Al3+ precipitation. The total weight of the system was adjusted to 1 kg to obtain a blocking agent. The gelation temperature, gelation onset time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0182] Example 13 This example illustrates an occlusive agent according to the present invention.

[0183] 10.5 g of hydrolyzed ligniamide L4 and 3.5 g of hydrolyzed acrylamide polymer III were dissolved in water with a mineralization level of 20,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 1.39 g of sodium bisulfite and 1.51 g of aluminum citrate were added, and the pH of the system was adjusted to prevent Al3+ precipitation. The total weight of the system was adjusted to 1 kg to obtain a blocking agent. The gelation temperature, gelation onset time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0184] Example 14 This example illustrates an occlusive agent according to the present invention.

[0185] A watertight and cross-sectional area adjusting system was prepared by the method of Example 5, except that hydrolyzed ligniamide L3 was replaced with ligniamide, and a blocking agent was obtained. The gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0186] Example 15 This example illustrates an occlusive agent according to the present invention.

[0187] A watertight and cross-sectional area adjusting system was prepared by the method of Example 11, except that hydrolyzed ligniamide L4 was replaced with ligniamide, and a blocking agent was obtained. The gelation temperature, gelation initiation time, and multiple viscosity after the cross-linking reaction, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 2.

[0188] Example 16 This example illustrates an occlusive agent according to the present invention.

[0189] A watertight and cross-sectional area adjusting system was prepared by the method of Example 12, except that hydrolyzed ligniamide L3 was replaced with ligniamide, and a blocking agent was obtained. The gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0190] Example 17 This example illustrates an occlusive agent according to the present invention.

[0191] A watertight and cross-sectional area adjusting system was prepared by the method of Example 13, except that hydrolyzed ligniamide L4 was replaced with ligniamide, and a blocking agent was obtained. The gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0192] Example 18 This example illustrates an occlusive agent according to the present invention.

[0193] A blocking agent was prepared in the same manner as in Example 5, except that hydrolyzed acrylamide polymer III was replaced with acrylamide polymer III. Table 2 shows the gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction.

[0194] Comparative Example 6 This comparative example illustrates a comparative occlusive agent.

[0195] A blocking agent was prepared according to the method of Example 5, except that the hydrolyzed ligniamide L3 was replaced with the same mass of hydrolyzed acrylamide polymer III. Table 2 shows the gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction.

[0196] Comparative Example 7 This comparative example illustrates a comparative occlusive agent.

[0197] A blocking agent was prepared according to the method of Example 11, except that the hydrolyzed ligniamide L4 was replaced with the same mass of hydrolyzed acrylamide polymer III. Table 2 shows the gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction.

[0198] Comparative Example 8 This comparative example illustrates a comparative occlusive agent.

[0199] A blocking agent was prepared according to the method of Example 12, except that the hydrolyzed ligniamide L3 was replaced with the same mass of hydrolyzed acrylamide polymer III. The gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0200] Comparative Example 9 This comparative example illustrates a comparative occlusive agent.

[0201] A blocking agent was prepared according to the method of Example 13, except that the hydrolyzed ligniamide L4 was replaced with the same mass of hydrolyzed acrylamide polymer III. The gelation temperature, gelation initiation time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0202] Comparative Example 10 This comparative example illustrates a comparative occlusive agent.

[0203] A blocking agent was prepared according to the method of Example 5, except that the hydrolyzed ligninamide L3 was replaced with the same mass of lignin. The gelation temperature, gelation onset time, and multiple viscosity, blocking rate, and breakthrough pressure gradient of the blocking agent after the crosslinking reaction are shown in Table 2.

[0204] [Table 2]

[0205] A comparison of the examples and comparative examples clearly shows that the present invention proposes a novel lignin-modified product and preparation method thereof, which is first applied to the oilfield water-blocking and cross-section-conditioning process. By aminating, acylating, and hydrolyzing lignin, the cross-linking sites of lignin are increased, improving the cross-linking activity of lignin and thereby improving the properties of the water-blocking and cross-section-conditioning agent. The water-blocking and cross-section-conditioning system of the present invention can controllably gel over a wide oil reservoir temperature range, has a blockage rate of greater than 89.2%, preferably greater than 98.3%, a breakthrough pressure gradient of greater than 1.25 MPa / m, preferably greater than 4.5 MPa / m, improved heat resistance, and high strength. The water-blocking and cross-section-conditioning system of the present invention has the characteristics of high system viscosity, high plugging strength, and high operating temperature. It effectively reduces the production costs of the water-blocking and cross-section-conditioning system, meets the performance, economical, and environmental requirements for on-site application, and is highly practical.

[0206] SPECIFIC EMBODIMENT III Preparation Example 6 This preparation example illustrates the preparation of ligniamide L6.

[0207] (1) At room temperature, 10 g of lignin and 1.6 g of NaOH were dissolved in water to prepare a 15 wt% lignin solution.

[0208] (2) Next, 12 g of diethylenetriamine was added dropwise, the pH was adjusted to 10.5, and 13.3 g of formaldehyde was added dropwise while stirring. The mixture was heated to reflux and reacted for 2.5 hours. After the reaction was completed, the pH was adjusted to approximately neutral, and the product was precipitated, washed, and dried to obtain the intermediate product, lignin amine.

[0209] (3) 6 g of lignin amine was dissolved in water, the pH was adjusted to 8.5, and 7.33 g of oleic acid chloride was added dropwise while stirring. The temperature was then raised to 60°C and the reaction was continued for 3 hours. After the reaction was completed, the solution was suction filtered, washed, dried, and pulverized to obtain ligniamide L6.

[0210] Preparation Example 7 This preparation illustrates the preparation of ligniamide L7.

[0211] Ligniamide L7 was obtained according to the method of Preparation Example 6, except that 12 g of diethylenetriamine was replaced with 23.1 g of tetraethylenepentamine and 7.33 g of oleic acid chloride was replaced with 6.93 g of palmitoyl chloride.

[0212] Preparation Example 8 This preparation illustrates the preparation of ligniamide L8.

[0213] Ligniamide L8 was obtained according to the method of Preparation Example 6, except that formaldehyde was not added in step (2).

[0214] Example 19 This example illustrates an occlusive agent according to the present invention.

[0215] 8.9 g of Ligniamide L7 and 3 g of acrylamide polymer VIII were dissolved in water with a mineralization level of 7000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 1.82 g of sodium bisulfite and 5.5 g of polyethyleneimine were added, the pH of the system was adjusted to 6.5, and the total mass of the system was adjusted to 1 kg. The mixture was then mixed uniformly to obtain a blocking agent. The gelation temperature, gelation initiation time, and viscosity and gel strength after the crosslinking reaction are shown in Table 3.

[0216] Example 20 This example illustrates an occlusive agent according to the present invention.

[0217] 4 g of Ligniamide L7 and 15 g of Acrylamide Polymer VIII were dissolved in water with a mineralization level of 12,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 5 g of sodium bisulfite and 8 g of polyethyleneimine were added, the pH of the system was adjusted to 7, and the total mass of the system was adjusted to 1 kg. The mixture was then mixed uniformly to obtain a blocking agent. The gelation temperature, gelation initiation time, and multiple viscosity and gel strength after the crosslinking reaction were shown in Table 3.

[0218] Example 21 This example illustrates an occlusive agent according to the present invention.

[0219] 20 g of Ligniamide L7 and 1 g of acrylamide polymer VIII were dissolved in water with a mineralization level of 10,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 10 g of sodium bisulfite and 2 g of polyethyleneimine were added, the pH of the system was adjusted to 7.5, and the total mass of the system was adjusted to 1 kg. The mixture was then mixed uniformly to obtain a blocking agent. The gelation temperature, gelation initiation time, and viscosity and gel strength after the crosslinking reaction were shown in Table 3.

[0220] Example 22 This example illustrates an occlusive agent according to the present invention.

[0221] A blocking agent was prepared according to the method of Example 19, except that sodium bisulfite was replaced with the same amount of sodium thiosulfate. The gelation temperature, gelation initiation time, and multi-viscosity and gel strength after the crosslinking reaction are shown in Table 3.

[0222] Example 23 This example illustrates an occlusive agent according to the present invention.

[0223] A blocking agent was prepared in the same manner as in Example 19, except that the acrylamide polymer VIII was replaced with the same amount of acrylamide polymer VII. The gelation temperature, gelation initiation time, multiple viscosity after the crosslinking reaction, and gel strength of the blocking agent are shown in Table 3.

[0224] Example 24 This example illustrates an occlusive agent according to the present invention.

[0225] A blocking agent was prepared in the same manner as in Example 19, except that the acrylamide polymer VIII was replaced with the same amount of acrylamide polymer IX. The gelation temperature, gelation initiation time, multiple viscosity after completion of the crosslinking reaction, and gel strength of the blocking agent are shown in Table 3.

[0226] Example 25 This example illustrates an occlusive agent according to the present invention.

[0227] A blocking agent was prepared according to the method of Example 19, except that Ligniamide L7 was replaced with Ligniamide L6. The gelation temperature, gelation initiation time, and multiple viscosity and gel strength after the crosslinking reaction of the blocking agent are shown in Table 3.

[0228] Example 26 This example illustrates an occlusive agent according to the present invention.

[0229] A blocking agent was prepared according to the method of Example 19, except that Ligniamide L7 was replaced with Ligniamide L8. The gelation temperature, gelation initiation time, and multiple viscosity and gel strength after the crosslinking reaction of the blocking agent are shown in Table 3.

[0230] Example 27 This example illustrates an occlusive agent according to the present invention.

[0231] 7 g of Ligniamide L6 and 4.4 g of Acrylamide Polymer VIII were dissolved in water with a mineralization level of 12,000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 1.46 g of sodium dithionite and 4.2 g of polyethyleneimine were added to adjust the pH of the system to 7.5, bringing the total weight of the system to 1 kg. The gelation temperature, gelation onset time, and viscosity and gel strength after the crosslinking reaction were shown in Table 3.

[0232] Comparative Example 11 This comparative example illustrates a comparative occlusive agent.

[0233] A blocking agent was prepared according to the method of Example 14, except that Ligninamide L7 was replaced with the same mass of acrylamide polymer VIII. The gelation temperature, gelation initiation time, and multiple viscosity and gel strength after the crosslinking reaction of the blocking agent are shown in Table 3.

[0234] Comparative Example 12 This comparative example illustrates a comparative occlusive agent.

[0235] A blocking agent was prepared according to the method of Example 27, except that Ligninamide L6 was replaced with the same mass of acrylamide polymer VIII. The gelation temperature, gelation initiation time, and multiple viscosity and gel strength after the crosslinking reaction of the blocking agent are shown in Table 3.

[0236] Comparative Example 13 This comparative example illustrates a comparative occlusive agent.

[0237] A blocking agent was prepared in the same manner as in Example 24, except that Ligninamide L7 was replaced with the same mass of acrylamide polymer IX. The gelation temperature, gelation initiation time, and multiple viscosity and gel strength after the crosslinking reaction are shown in Table 3.

[0238] Comparative Example 14 This comparative example illustrates a comparative occlusive agent.

[0239] A blocking agent was prepared according to the method of Example 19, except that ligninamide L7 was replaced with the lignin amine prepared in step (2). The gelation temperature, gelation onset time, and multi-viscosity and gel strength of the blocking agent after the crosslinking reaction are shown in Table 3.

[0240] Comparative Example 15 This comparative example illustrates a comparative occlusive agent.

[0241] A blocking agent was prepared according to the method of Example 14, except that Ligninamide L7 was replaced with the same mass of lignin. The gelation temperature, gelation initiation time, and multiple viscosity and gel strength after the crosslinking reaction of the blocking agent are shown in Table 3.

[0242] [Table 3]

[0243] A comparison of the Examples and Comparative Examples clearly shows that the present invention proposes a novel lignin-modified product and its preparation method, which are used for the first time in the process of oilfield water-blocking and cross-section adjustment. The amination and acylation of lignin increases the number of cross-linking sites in lignin, improving its cross-linking activity and, as a result, improving the properties of the water-blocking and cross-section adjustment agent. The blocking agent of the present invention can controllably delay cross-linking at a high gelation temperature (55-100°C) and a long gelation time (3.5-9 days), and produces a jelly with high strength, while also effectively reducing production costs.

[0244] SPECIFIC EMBODIMENT IV Preparation Example 9 This preparation illustrates the preparation of ligniamide L9.

[0245] (1) At room temperature, 10 g of lignin and 1.53 g of NaOH were dissolved in water and stirred at 400 r / min to prepare a 15 wt% lignin solution.

[0246] (2) Next, 12 g of diethylenetriamine was added dropwise, the pH was adjusted to 10.7, and 14.8 g of formaldehyde was added dropwise at a stirring speed of 350 r / min. The mixture was heated to reflux and reacted for 2.8 hours. After the reaction was completed, the pH was adjusted to approximately neutral, and the product was precipitated, washed, and dried to obtain the intermediate product, lignin amine.

[0247] (3) 6 g of lignin amine was dissolved in water, the pH was adjusted to 8.6, and 7.48 g of oleic acid chloride was added dropwise at a stirring speed of 350 r / min. The temperature was then raised to 55°C and the reaction was continued for 2.75 h. After the reaction was completed, the solution was suction filtered, washed, dried and pulverized to obtain ligniamide L9.

[0248] Preparation Example 10 This preparation illustrates the preparation of ligniamide L10.

[0249] Ligniamide L10 was obtained in the same manner as in Preparation Example 9, except that 12 g of diethylenetriamine was replaced with 18.2 g of tetraethylenepentamine and 7.48 g of oleic acid chloride was replaced with 6.85 g of palmitoyl chloride.

[0250] Preparation Example 11 This preparation illustrates the preparation of ligniamide L11.

[0251] The ligniamide product L11 was obtained in the same manner as in Preparation Example 9, except that formaldehyde was not added in step (2).

[0252] Example 28 This example illustrates an occlusive agent according to the present invention.

[0253] 7 g of Ligniamide L9 and 2.6 g of acrylamide polymer VIII were dissolved in water with a mineralization level of 5000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 0.52 g of sodium bisulfite, 0.81 g of sodium dithionite, and 5.7 g of phenolic resin were added to bring the total mass to 1 kg and mixed uniformly to obtain a blocking agent. The gelation temperature, post-gelation viscosity, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0254] Example 29 This example illustrates an occlusive agent according to the present invention.

[0255] 4 g of Ligniamide L9 and 5 g of acrylamide polymer VIII were dissolved in water with a mineralization level of 4000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 2.35 g of sodium bisulfite, 2.15 g of sodium dithionite, and 2 g of phenolic resin were added to bring the total mass to 1 kg and mixed uniformly to obtain a blocking agent. The gelation temperature, post-gelation viscosity, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0256] Example 30 This example illustrates an occlusive agent according to the present invention.

[0257] 20 g of Ligniamide L9 and 1 g of acrylamide polymer VIII were dissolved in water with a mineralization level of 3000 mg / L and stirred at 500 r / min until uniformly dissolved. Next, 0.08 g of sodium bisulfite, 0.12 g of sodium dithionite, and 20 g of phenolic resin were added to bring the total mass to 1 kg and mixed uniformly to obtain a blocking agent. The gelation temperature, post-gelation viscosity, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 3.

[0258] Example 31 This example illustrates an occlusive agent according to the present invention.

[0259] A blocking agent was prepared according to the method of Example 28, except that only sodium bisulfite was used as a stabilizer in an amount of 1.33 g. The gelation temperature, viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0260] Example 32 This example illustrates an occlusive agent according to the present invention.

[0261] A blocking agent was prepared according to the method of Example 28, except that only sodium dithionite was used as a stabilizer in an amount of 1.33 g. The gelation temperature, multiple viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0262] Example 33 This example illustrates an occlusive agent according to the present invention.

[0263] A blocking agent was prepared according to the method of Example 28, except that sodium bisulfite was replaced with the same amount of thiourea and sodium dithionite with the same amount of isoascorbic acid as stabilizers. The gelation temperature, multiple viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0264] Example 34 This example illustrates an occlusive agent according to the present invention.

[0265] A blocking agent was prepared in the same manner as in Example 28, except that the acrylamide polymer VIII was replaced with the same amount of acrylamide polymer VII. The gelation temperature, multiple viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0266] Example 35 This example illustrates an occlusive agent according to the present invention.

[0267] A blocking agent was prepared in the same manner as in Example 28, except that the acrylamide polymer VIII was replaced with the same amount of acrylamide polymer IX. The gelation temperature, multiple viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0268] Example 36 This example illustrates an occlusive agent according to the present invention.

[0269] A plugging agent was prepared according to the method of Example 28, except that Ligniamide L9 was replaced with Ligniamide L10. The gelation temperature, viscosity after gelation, gel retention time at the gelation temperature, plugging rate, and breakthrough pressure gradient of the plugging agent are shown in Table 4.

[0270] Example 37 This example illustrates an occlusive agent according to the present invention.

[0271] A plugging agent was prepared according to the method of Example 28, except that Ligniamide L9 was replaced with Ligniamide L11. The gelation temperature, viscosity after gelation, gel retention time at the gelation temperature, plugging rate, and breakthrough pressure gradient of the plugging agent are shown in Table 4.

[0272] Comparative Example 16 This comparative example illustrates a comparative occlusive agent.

[0273] A blocking agent was prepared according to the method of Example 28, except that ligniamide was replaced with the same mass of acrylamide polymer VIII. The gelation temperature, multiple viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0274] Comparative Example 17 This comparative example illustrates a comparative occlusive agent.

[0275] A blocking agent was prepared in the same manner as in Example 35, except that ligniamide was replaced with the same mass of acrylamide polymer IX. Table 4 shows the gelation temperature, multiple viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent.

[0276] Comparative Example 18 This comparative example illustrates a comparative occlusive agent.

[0277] A blocking agent was prepared according to the method of Example 28, except that ligninamide L9 was replaced with the lignin amine prepared in step (2). The gelation temperature, viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent are shown in Table 4.

[0278] Comparative Example 19 This comparative example illustrates a comparative occlusive agent.

[0279] A blocking agent was prepared according to the method of Example 28, except that Ligninamide L9 was replaced with the same mass of lignin. Table 4 shows the gelation temperature, multiple viscosity after gelation, gel retention time at the gelation temperature, blocking rate, and breakthrough pressure gradient of the blocking agent.

[0280] [Table 4]

[0281] A comparison of the examples and comparative examples clearly shows that the present invention proposes a novel lignin-modified product and its preparation method, which are used for the first time in the process of oilfield water-blocking and cross-section adjustment. The amination and acylation of lignin increases the number of cross-linking sites in lignin, improving the cross-linking activity of lignin and thereby improving the properties of the water-blocking and cross-section adjustment agent. The plugging agent of the present invention can effectively block steam channels for long periods of time at high reservoir temperatures (140-250°C) and for long periods of time (50-120 days), and has high strength. Therefore, the plugging agent of the present invention can effectively block high-permeability layers, adjust the difference in steam absorption between the high-permeability and low-permeability layers of the formation, and redirect the flow of injected steam. This reduces steam channeling, eliminates interwell interference, increases the volume of injected steam, and achieves the goals of improving periodic oil recovery and promoting efficient development of high-temperature oil reservoirs.

Claims

1. A method for preparing a plugging agent for oil field oil production, comprising the step of catalytically reacting ligniamide, an acrylamide polymer, a crosslinking agent, and a stabilizer in the presence of a solvent to obtain the plugging agent for oil field oil production.

2. The method of claim 1, wherein the ligniamide is hydrolyzed ligniamide.

3. (1) reacting a lignin solution with an organic amine under a first alkaline condition to form a lignin amine; (2) acylation of lignin amine with acyl chloride in a solution under a second alkaline condition to obtain the ligniamide; 3. The method according to claim 1 or 2, optionally comprising the step (3) of hydrolyzing ligniamide with a hydrolysis agent to obtain hydrolyzed ligniamide.

4. The lignin in the lignin solution is at least one selected from alkaline lignin, enzymatically decomposed lignin, chlorinated lignin, steam-exploded lignin, lignosulfonate, and thiolignin; and / or the pH value of the first alkaline condition is 10 to 11.5, and the mass ratio of the organic amine to the lignin is 0.05 to 4.5:1; and / or the conditions of the conversion reaction to amines include a temperature of 60 to 75°C and a time of 1.5 to 4 hours; and / or the second alkaline condition has a pH value of 8 to 9.5, and a mass ratio of the acyl chloride to the lignin amine is 0.5 to 2.5:1; and / or the acylation reaction conditions include a temperature of 55 to 65°C and a time of 1 to 4 hours; and / or the mass ratio of the hydrolyzing agent to the ligniamide is 0.0001 to 0.8:1; And / or the preparation method according to claim 3, wherein the hydrolysis reaction conditions include a temperature of 60 to 80°C and a time of 2 to 12 hours.

5. 5. The method according to claim 4, wherein the organic amine is at least one selected from the group consisting of dimethylamine, ethylenediamine, trimethylamine, triethylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, putrescine, cadaverine, spermidine, and spermine.

6. The preparation method according to claim 4, wherein the amination reaction is carried out in the presence of an aldehyde, and the aldehyde is a C1-C5 aldehyde.

7. 5. The method according to claim 4, wherein the acyl chloride is at least one selected from acetyl chloride, benzoyl chloride, oxalyl chloride, chloroacetyl chloride, trichloroacetyl chloride, fatty acid chloride, stearyl chloride, linoleyl chloride, oleic acid chloride, and palmitoyl chloride.

8. 5. The method of claim 4, wherein the hydrolysis agent is at least one of sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, and potassium hydroxide solution.

9. The method according to any one of claims 1 to 8, wherein the acrylamide polymer is at least one selected from the group consisting of an anionic acrylamide compound, a cationic acrylamide compound, a nonionic acrylamide compound, and an amphoteric acrylamide compound.

10. The method according to claim 9, wherein the weight-average molecular weight of the acrylamide polymer is 5 million to 35 million.

11. the acrylamide polymer is a hydrolyzed acrylamide polymer, 10. The method according to claim 9, wherein the degree of hydrolysis of the hydrolyzed acrylamide polymer is 15-30%.

12. The preparation method according to any one of claims 1 to 11, wherein the crosslinking agent is at least one selected from the group consisting of an aluminum crosslinking agent, a polyethyleneimine, a phenolic resin, and a chromium crosslinking agent.

13. the aluminum crosslinker is aluminum citrate and / or polyaluminum; the chromium crosslinking agent is at least one selected from sodium dichromate, ammonium dichromate, and potassium dichromate; 13. The method according to claim 12, wherein the stabilizer is at least one selected from the group consisting of sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium dithionite, m-phenylenediamine, isoascorbic acid, and thiourea.

14. The preparation method according to claim 12 or 13, wherein the weight average molecular weight of the polyethyleneimine is 3,000 to 100,000.

15. The method according to any one of claims 1 to 14, wherein, based on the total weight of the oil field oil extraction plugging agent, the content of the ligniamide is 0.1 to 5.5 wt%, the content of the acrylamide polymer is 0.01 to 3.5 wt%, the content of the crosslinking agent is 0.05 to 4.5 wt%, and the content of the stabilizer is 0.01 to 2.5 wt%.

16. 16. The method of claim 15, wherein, based on the total weight of the oilfield plugging agent, the content of the ligniamide is 0.4-2 wt %, the content of the acrylamide polymer is 0.01-1.5 wt %, the content of the crosslinking agent is 0.05-2 wt %, and the content of the stabilizer is 0.02-1 wt %.

17. further comprising a pH adjuster; The preparation method according to any one of claims 1 to 16, wherein the content of the pH adjuster is 0.01 to 0.45 wt% based on the total weight of the oil field oil recovery plugging agent.

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