An anti-channeling plugging system, a preparation method and a method for nitrogen gas drive anti-gas channeling

Abstract

The application provides a gas channeling prevention plugging system, a preparation method and a method for preventing gas channeling during nitrogen flooding, and relates to the technical field of oil production. The gas channeling prevention plugging system comprises a gel foam plugging agent and a foam plugging agent. The gel foam plugging agent comprises the following components in percentage by mass: 0.5-1% of hydrolyzed polyacrylamide, 0.3-0.8% of alkyl benzene sulfonate, 0.5-1% of carboxylated gellan gum, 0.1-0.5% of a crosslinking agent, and the rest is water. The foam plugging agent comprises the following components in percentage by mass: 0.5-1% of a fatty alcohol polyoxyethylene ether, 0.5-1% of an alkyl imino diacetate or an alkyl imino dipropionate, 0.1-0.3% of an acyl methyl taurinate, and the rest is water. The gas channeling prevention plugging agent has good high-temperature and high-salt resistance, can realize efficient plugging, and thus can expand the gas flooding volume and improve the crude oil recovery.

Description

Technical Field

[0001] This application relates to the field of oil production technology, and in particular to an anti-channeling and plugging system, a preparation method thereof, and a method for using the same for nitrogen-driven anti-channeling. Background Technology

[0002] Nitrogen injection is a crucial method for improving oil recovery. During nitrogen injection, nitrogen replaces the gas in the crude oil, reducing the interaction forces between the gas and crude oil in the reservoir, improving crude oil flowability, and thus increasing recovery. However, gas channeling occurs in some well groups during nitrogen injection, leading to a significant decrease in nitrogen utilization and a reduction in the gas-driven sweep volume, severely impacting oil displacement efficiency. Furthermore, remediating gas channeling after it occurs is difficult and costly. Therefore, preventing gas channeling and plugging during nitrogen injection is essential for improving oil displacement efficiency.

[0003] Injecting anti-channeling plugging agents is currently an important means of preventing and delaying gas channeling. Conventional anti-channeling plugging agents mainly include foam-based, resin-based, precipitated, and gel / gel-based agents. However, conventional plugging agents have problems such as poor temperature and salt resistance, short sealing effectiveness, and insignificant oil recovery. Patent CN104140797A discloses a gas-driven anti-channeling agent composed of a mixture B (a gelling agent, acidity regulator, and water) and an organic amine A. This anti-channeling agent can withstand temperatures of 90-120℃ and salt concentrations of 30×10⁻⁶. 4 mg / L. However, the temperature in high-temperature and high-salinity reservoirs is generally above 120℃. This anti-channeling agent exhibits poor stability and poor plugging effect at temperatures above 120℃, making it unsuitable for the development of such reservoirs. Therefore, it is still necessary to develop new anti-channeling and plugging systems to be suitable for the development of high-temperature and high-salinity reservoirs and achieve efficient plugging. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects and deficiencies in the prior art and provide an anti-channeling and plugging system, a preparation method, and a method for using it to prevent gas channeling during nitrogen drive. This anti-channeling and plugging agent has good high temperature and high salt resistance properties, and can achieve efficient plugging, thereby increasing the gas drive volume and improving crude oil recovery.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: According to one aspect of this application, an anti-channeling and plugging system is provided, including a gel foam plugging agent and a foam plugging agent; The gel foam sealant comprises, by mass percentage, the following components: 0.5-1% hydrolyzed polyacrylamide, 0.3-0.8% alkylbenzene sulfonate, 0.5-1% carboxylated gellan gum, 0.1-0.5% crosslinking agent, and the balance being water; The foam sealing agent comprises, by mass percentage, the following components: 0.5-1% fatty alcohol polyoxyethylene ether, 0.5-1% alkyl iminodiacetate or alkyl iminodiapropionate, 0.1-0.3% acylmethyl taurate, and the balance being water.

[0006] This application provides the above-mentioned anti-channeling and plugging system. Both the gel foam plugging agent and the foam plugging agent have the characteristics of high temperature and high salt resistance. The gel foam plugging agent can effectively block the large channels of nitrogen gas channeling, while the foam plugging agent can effectively block the small channels of nitrogen gas channeling. The two work together to achieve efficient plugging, thereby expanding the affected area and improving the recovery rate.

[0007] Furthermore, the hydrolyzed polyacrylamide has a weight-average molecular weight of 15-20 million and a degree of hydrolysis of 20-30%.

[0008] Furthermore, the alkylbenzene sulfonate is selected from C18 to C30 alkylbenzene sulfonates, where C18 to C30 refers to the carbon chain length of the alkyl chain, that is, a branched or straight alkyl chain with 18 to 30 carbon atoms. For example, the alkylbenzene sulfonate can be octadecylbenzene sulfonate C18-ABS, eicosylbenzene sulfonate C20-ABS, dodecylbenzene sulfonate C22-ABS, tetradecylbenzene sulfonate C24-ABS, hexadecylbenzene sulfonate C26-ABS, octadecylbenzene sulfonate C28-ABS, and triacontylbenzene sulfonate C30-ABS.

[0009] Furthermore, the carboxylated gellan gum is obtained by reacting low-acyl gellan gum, high-acyl gellan gum, and a carboxylating agent. The degree of carboxyl substitution in the carboxylated gellan gum is 0.45–0.55 mmol / g. The carboxylating agent is chloroacetic acid, sodium chloroacetate, etc., which are well known to those skilled in the art. The reaction method is also a method well known to those skilled in the art. As long as a carboxylated gellan gum with a degree of carboxyl substitution of 0.45–0.55 mmol / g can be obtained, there are no special requirements.

[0010] In some embodiments, carboxylated gellan gum is obtained by reacting it with sodium chloroacetate. The preparation method is as follows: gellan gum is dispersed in isopropanol, sodium hydroxide solution is added, and it is activated at room temperature for 1 to 1.5 h. Then sodium chloroacetate is added, and it is reacted at 50 to 60 °C for 3 to 4 h. After neutralization, it is washed with ethanol and dried to obtain carboxylated gellan gum.

[0011] Furthermore, the above-mentioned carboxylated gellan gum preparation process includes the following limitations: The gellan gum is a low-acyl gellan gum and a high-acyl gellan gum with a mass ratio of (88-95):(5-12); The solid-liquid ratio of gellan gum to isopropanol is 1 g: (10-15) mL; The amount of sodium hydroxide added is 40-50% of the mass of gellan gum, and the sodium hydroxide is added in the form of an aqueous solution with a mass fraction of 20-30%. The amount of sodium chloroacetate added is 25-35% of the mass of gellan gum.

[0012] While gellan gum exhibits good temperature and salt resistance, the gel strength formed when combined with materials such as hydrolyzed polyacrylamide is limited. This application utilizes sodium chloroacetate to carboxylate gellan gum, introducing active sites into the treated gellan gum, resulting in a more stable network structure and improved temperature and salt resistance, making it suitable for high-temperature, high-salt reservoirs. Furthermore, the addition of carboxylated gellan gum also provides a certain degree of foam stabilization, extending the sealing time.

[0013] In a further embodiment, the carboxylated gellan gum is further modified using 4,4'-diaminodiphenylamine-2-sulfonic acid. This modification involves first dispersing the carboxylated gellan gum in an isopropanol solution, adding EDC and NHS for activation, and then adding 4,4'-diaminodiphenylamine-2-sulfonic acid to react and obtain the final product. Specifically, the modification steps are as follows: (1) Disperse carboxylated gellan gum in isopropanol solution, add EDC and NHS, adjust pH to 5-5.5, and activate at room temperature for 30-50 min; (2) Then add 4,4'-diaminodiphenylamine-2-sulfonic acid, react at 40-45℃ for 3-4 hours, add anhydrous ethanol to precipitate, wash, and dry to obtain modified gellan gum.

[0014] Optionally, the above modification method includes the following limitations: The solid-liquid ratio of the carboxylated gellan gum to the isopropanol solution is 1g:(15-20)mL, and the volume ratio of isopropanol to water in the isopropanol solution is (2-3):(7-8). The mass ratio of the carboxylated gellan gum to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is 1:(0.04-0.05):(0.02-0.03). The mass ratio of the 4,4'-diaminodiphenylamine-2-sulfonic acid to the carboxylated gellan gum is (3-7):100.

[0015] Studies have found that further modification of carboxylated gelling gum with 4,4'-diaminodiphenylamine-2-sulfonic acid further improves the system's resistance to high temperature and high salt. The resulting system is suitable for reservoirs with a salinity of 350,000 mg / L at 150℃, without affecting its foaming and foam stabilization properties, and can still maintain the stability of gelling gum foam.

[0016] Furthermore, the crosslinking agent comprises an aldehyde crosslinking agent, which is selected from any one or a combination of several of glyoxal, succinaldehyde, glutaraldehyde, adipaldehyde, o-phenylenedialdehyde, nonadialdehyde, octanaldehyde, and paraformaldehyde.

[0017] Furthermore, the crosslinking agent also contains isophorone diamine, and the mass ratio of isophorone diamine to aldehyde crosslinking agent is (10-30):(70-90).

[0018] Adding isophorone diamine to gel foam plugging agents, in combination with modified gellan gum and other components, helps the system form a more stable network structure underground, achieving long-term plugging and improving crude oil recovery.

[0019] Furthermore, the fatty alcohol polyoxyethylene ether in the foam sealant has the structural formula shown in formula (I): RO-[CH2-CH2-O] m -H type (I); In formula (I), 9 ≤ m ≤ 16, that is, m is an integer from 9 to 16, and R is an alkyl group from C12 to C18; For example, the fatty alcohol polyoxyethylene ether is dodecyl alcohol polyoxyethylene ether (9), tetradecyl alcohol polyoxyethylene ether (9), hexadecyl alcohol polyoxyethylene ether (9), octadecyl alcohol polyoxyethylene ether (9), dodecyl alcohol polyoxyethylene ether (10), tetradecyl alcohol polyoxyethylene ether (10), hexadecyl alcohol polyoxyethylene ether (10), octadecyl alcohol polyoxyethylene ether (10), dodecyl alcohol polyoxyethylene ether (16), tetradecyl alcohol polyoxyethylene ether (16), hexadecyl alcohol polyoxyethylene ether (16), octadecyl alcohol polyoxyethylene ether (16), etc., or it can be dodecyl / tetradecyl alcohol polyoxyethylene ether (9), tetradecyl / hexadecyl alcohol polyoxyethylene ether (9), hexadecyl / octadecyl alcohol polyoxyethylene ether (9), etc., the "(9)" in the chemical name is m in the above structural formula (I), and " / " indicates mixed carbon, for example, "dodecyl / tetradecyl" indicates a mixture of C12 fatty alcohol and C14 fatty alcohol.

[0020] Furthermore, the acylmethyl taurine in the foam sealant is selected from lauroyl methyl taurine and / or cocoyl methyl taurine, and the salt is a sodium salt or a potassium salt.

[0021] Further, the alkyl iminodiacetate or alkyl iminodiapropionate is an amphoteric surfactant selected from at least one of disodium cocoaminopropyl iminodiacetate, disodium hydroxyethyl iminodiacetate, disodium lauryl iminodiacetate, disodium lauryl iminodiapropionate, disodium stearyl iminodiapropionate, disodium tallow iminodiapropionate, C12-15 alkoxypropyl iminodiapropionate, sodium cocoaminodiacetate, and sodium lauryl iminodiapropionate.

[0022] In the above-mentioned foam plugging agent, the three surfactants work together to have good foaming and foam stabilizing properties. The foam generated in the formation avoids gas channeling during nitrogen flooding and has good temperature and salt resistance, making it suitable for high-temperature and high-salinity oil reservoirs.

[0023] Furthermore, in the above-mentioned gel foam sealant and foam sealant, the water is selected from any one of tap water, formation water, and mineralized water.

[0024] According to another aspect of this application, a method for preparing the above-mentioned anti-channeling and blocking system is provided, comprising the following steps: S1. Mix hydrolyzed polyacrylamide, alkylbenzene sulfonate, and carboxylated gelling gel evenly, add crosslinking agent and mix well to obtain the gelling foam sealant. S2. Dissolve fatty alcohol polyoxyethylene ether, alkyl iminodiacetate or alkyl iminodiapropionate, or acylmethyl taurate in water to obtain the foam sealant.

[0025] According to another aspect of this application, a method for preventing gas channeling in nitrogen-driven gas flow using the above-mentioned anti-channeling and plugging system is provided, comprising: first injecting a gel foam plugging agent into the formation to block large channels, and then injecting a foam plugging agent to block small channels.

[0026] Compared with the prior art, this application has the following beneficial effects: 1. The anti-gas migration and plugging system provided in this application, wherein the gel foam plugging agent can form a high-strength network structure in the formation, which can effectively block the large channels of nitrogen gas migration, and the foam formed by the foam plugging agent in the formation can effectively block the small channels of nitrogen gas migration. The two work together to achieve efficient plugging, thereby expanding the affected area and improving the recovery rate.

[0027] 2. The addition of carboxylated gellan gum to the gel foam sealant of this application further improves the temperature resistance and mineralization resistance of the gel foam sealant, and also plays a certain role in stabilizing foam and prolonging the sealing time; and after further modification of the carboxylated gellan gum with 4,4'-diaminodiphenylamine-2-sulfonic acid, the high temperature and high salt resistance of the system can be further improved without affecting the foaming and foam stabilizing performance.

[0028] 3. The foam plugging agent of this application contains three surfactants that work together to produce good foaming and stabilizing properties, as well as excellent resistance to high temperature and high salt, thus achieving effective plugging. Detailed Implementation

[0029] To more clearly illustrate the overall concept of this application, a detailed description is provided below with reference to embodiments. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with the invention.

[0030] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers. Preparation methods that do not specify specific methods are generally prepared using equipment or conventional methods well known in the art.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0033] Unless otherwise specified, in the following embodiments, reagents or instruments whose manufacturers are not indicated are all conventional products that can be purchased commercially.

[0034] Unless otherwise stated, the experimental methods, detection methods and preparation methods disclosed in this invention all adopt conventional techniques in this technical field.

[0035] In the following specific embodiments, the carboxylated gellan gum is only an example of a carboxylated gellan gum prepared by one method. It should be understood that other carboxylating reagents and preparation methods well known to those skilled in the art can also achieve the technical effects of this application, as long as the degree of carboxyl substitution is satisfied. Both the high- and low-acyl gellan gums of this application can be directly obtained commercially or prepared by methods well known in the art, such as those generated by the microorganism *Sphingomonas elodea*. In the following specific embodiments, the high-acyl gellan gum was purchased from CPKelco, Inc.'s KELCOGELLT100, and the low-acyl gellan gum was prepared using the method described in patent CN201310347818.6. Hydrolyzed polyacrylamide was purchased from Aisen (China) Flocculant Co., Ltd.

[0036] The present application will be further described below by way of specific embodiments.

[0037] Example 1 This embodiment provides an anti-channeling and plugging system, including a gel foam plugging agent and a foam plugging agent; The gel foam sealant comprises the following components by mass percentage: 0.5% hydrolyzed polyacrylamide (weight average molecular weight of 15 million, degree of hydrolysis of 20%), 0.3% C18-ABS, 0.5% carboxylated gellan gum (degree of carboxyl substitution of 0.45 mmol / g), 0.1% glyoxal, and the balance being tap water; The foam sealant, by mass percentage, comprises the following components: 0.5% dodecyl polyoxyethylene ether (9), 0.5% disodium lauryl iminodiacetate, 0.1% sodium lauroyl methyl taurate, with the remainder being tap water; The carboxylated gellan gum with a carboxyl substitution degree of 0.45 mmol / g was prepared by the following method: 10 g of gellan gum (the mass ratio of low-acyl gellan gum to high-acyl gellan gum was 88:12) was dispersed in 100 mL of isopropanol, 20 mL of sodium hydroxide solution with a mass fraction of 20% was added, and the mixture was activated at room temperature for 1 h. Then, 2.5 g of sodium chloroacetate was added, and the mixture was reacted at 50 °C for 3 h. After neutralization, the mixture was washed with ethanol and dried to obtain the carboxylated gellan gum.

[0038] The preparation method of the above-mentioned anti-channeling and blocking system includes the following steps: Hydrolyzed polyacrylamide, C18-ABS, carboxylated gelling glue and tap water are mixed evenly, and glyoxal is added and mixed evenly to obtain gelling foam sealant. S2. Dissolve dodecyl alcohol polyoxyethylene ether (9), disodium lauryl iminodiacetate, and sodium lauroyl methyl taurate in tap water to obtain the foam sealant.

[0039] Example 2 This embodiment provides another anti-channeling and plugging system, including gel foam plugging agent and foam plugging agent; The gel foam sealant comprises the following components by mass percentage: 1% hydrolyzed polyacrylamide (weight average molecular weight of 20 million, degree of hydrolysis of 30%), 0.8% C30-ABS, 1% carboxylated gellan gum (degree of carboxyl substitution of 0.55 mmol / g), 0.5% succinaldehyde, and the balance being tap water. The foam sealant, by mass percentage, comprises the following components: 1% octadecyl alcohol polyoxyethylene ether (16), 1% disodium tartrate iminodipropionate, 0.3% sodium cocoyl methyl taurate, and the remainder is tap water; Carboxylated gellan gum with a carboxyl substitution degree of 0.55 mmol / g was prepared by the following method: 10 g of gellan gum (the mass ratio of low-acyl gellan gum to high-acyl gellan gum was 95:5) was dispersed in 100 mL of isopropanol, 20 mL of sodium hydroxide solution with a mass fraction of 20% was added, and the mixture was activated at room temperature for 1 h. Then, 3.5 g of sodium chloroacetate was added, and the mixture was reacted at 60 °C for 4 h. After neutralization, the mixture was washed with ethanol and dried to obtain carboxylated gellan gum.

[0040] The preparation method of the above-mentioned anti-channeling and blocking system includes the following steps: Hydrolyzed polyacrylamide, C30-ABS, carboxylated gelling glue, and tap water are mixed evenly, and glyoxal is added and mixed evenly to obtain gelling foam sealant. S2. Dissolve octadecyl alcohol polyoxyethylene ether (16), disodium tartrate iminodipropionate, and sodium cocoyl methyl taurate in tap water to obtain the foam sealant.

[0041] Example 3 The difference from Example 1 is that in the preparation process of carboxylated gellan gum, only low-acyl gellan gum is produced, and the total amount remains unchanged.

[0042] Example 4 This embodiment provides another anti-channeling and plugging system, which is basically the same as that in Example 2, except that the carboxylated gelling gel in the gel foam plugging agent is further modified with 4,4'-diaminodiphenylamine-2-sulfonic acid. The modification method is as follows: 10g of carboxylated gellan gum was dispersed in 200mL of isopropanol solution (the volume ratio of isopropanol to water in the isopropanol solution was 3:7), 0.4g of EDC and 0.2g of NHS were added, the pH was adjusted to 5, and the mixture was activated at room temperature for 30min. Then, 0.3g of 4,4'-diaminodiphenylamine-2-sulfonic acid was added, and the mixture was reacted at 40℃ for 3h. Anhydrous ethanol was added to precipitate the mixture, and the product was washed and dried to obtain the modified gellan gum.

[0043] Example 5 This embodiment provides another anti-channeling and plugging system, which is basically the same as that in Example 2, except that the carboxylated gelling gel in the gel foam plugging agent is further modified with 4,4'-diaminodiphenylamine-2-sulfonic acid. The modification method is as follows: 10g of carboxylated gellan gum was dispersed in 150mL of isopropanol solution (the volume ratio of isopropanol to water in the isopropanol solution was 3:7), 0.5g of EDC and 0.3g of NHS were added, the pH was adjusted to 5.5, and the mixture was activated at room temperature for 50min. Then, 0.7g of 4,4'-diaminodiphenylamine-2-sulfonic acid was added, and the mixture was reacted at 45℃ for 4h. Anhydrous ethanol was added to precipitate the mixture, and the product was washed and dried to obtain the modified gellan gum.

[0044] Example 6 This embodiment provides another anti-channeling and blocking system, which is basically the same as that in Example 2, except that the amount of 4,4'-diaminodiphenylamine-2-sulfonic acid is 1g, that is, the mass ratio of 4,4'-diaminodiphenylamine-2-sulfonic acid to carboxylated gellan gum is 1:10.

[0045] Example 7 This embodiment provides another anti-channeling and blocking system, which is basically the same as that in embodiment 2. The difference is that the crosslinking agent also contains isophorone diamine, and the mass ratio of glyoxal to isophorone diamine is 10:90, while the total amount of crosslinking agent remains unchanged.

[0046] Example 8 This embodiment provides another anti-channeling and blocking system, which is basically the same as that in embodiment 2. The difference is that the crosslinking agent also contains isophorone diamine, and the mass ratio of glyoxal to isophorone diamine is 30:70, while the total amount of crosslinking agent remains unchanged.

[0047] Example 9 This embodiment provides another anti-channeling and blocking system, which is basically the same as that in embodiment 2, except that the mass ratio of glyoxal to isophorone diamine in the crosslinking agent is 1:1.

[0048] Comparative Example 1 This comparative example provides another anti-channeling and plugging system, which is basically the same as Example 2, except that the carboxylated gellan gum in the gel foam plugging agent is replaced with an equal amount of gellan gum.

[0049] Comparative Example 2 This comparative example provides another anti-channeling and plugging system, which is basically the same as Example 2, except that no carboxylated gelling gel is added to the gel foam plugging agent.

[0050] Comparative Example 3 This comparative example provides another anti-channeling and plugging system, which is basically the same as Example 2, except that the foam plugging agent, by mass percentage, includes the following components: 1.5% fatty alcohol polyoxyethylene ether, 0.3% disodium tallow iminodipropionate, 0.5% acylmethyl taurate, and the balance being water.

[0051] Comparative Example 4 This comparative example provides another anti-channeling and plugging system, which is basically the same as Example 2, except that disodium tallow iminodipropionate is not added to the foam plugging agent.

[0052] Comparative Example 5 This comparative example provides another anti-channeling and plugging system, which is basically the same as Example 2, except that sodium lauroyl methyl taurate is not added to the foam plugging agent.

[0053] Experimental Example 1 Performance testing of gel foam sealant Foam performance: The foaming volume and half-life of 50 mL of gel foam sealant at room temperature were tested using the Waring-Blender method.

[0054] High temperature stability: After aging the gel foam sealant at 150℃ for 72 hours, the foaming volume and liquid separation half-life were tested.

[0055] High salt stability: Uses a mineralization of 30×10 4 The foam sealant was replaced with simulated formation water at a concentration of mg / L to test the foaming volume and the half-life of the liquid.

[0056] The test results are shown in Table 1 below.

[0057] Table 1. Performance of Gel Foam Sealant

[0058] As shown in the table, the gel foam sealant provided in this application has excellent foaming properties and excellent high temperature and high salt resistance, and can be used at 150℃ and 30×10 4 Oil reservoirs with a salinity of mg / L.

[0059] Experimental Example 2 Performance testing of foam sealing agents Foam performance: The foaming volume and half-life of 10 mL of foam sealant at room temperature were tested using the Waring-Blender method.

[0060] High temperature stability: After aging the foam sealant at 150℃ for 72 hours, the foaming volume and liquid half-life were tested.

[0061] High salt stability: Uses a mineralization of 30×10 4 The foam sealant was replaced with simulated formation water at a concentration of mg / L to test the foaming volume and the half-life of the liquid.

[0062] The test results are shown in Table 2 below.

[0063] Table 2. Performance of Foam Blocking Agents

[0064] The results show that the foam sealant provided in this application has excellent foaming properties and excellent high temperature and salt resistance.

[0065] Experimental Example 3 Anti-channeling and blocking performance test First inject the gel foam sealant, then inject the foam sealant. A simulated core was prepared (core diameter d = 25 mm, length L = 200 mm). After vacuuming, water was injected into the core at a flow rate of 2 ml / min (injection rate Q), and the permeability (k0) before plugging was measured. First, 1.0 PV of gel foam sealant was injected into the core mold, followed by 0.5 PV of foam sealant to plug both ends of the core. The core was then placed in a 150℃ constant temperature chamber and left to stand for 30 days. Water was injected again until the pressure stabilized, and the permeability (k) after plugging was obtained. The plugging rate η was then calculated using the following formula: The blocking rate η = (k0-k) / k0 × 100%.

[0066] The test results are shown in Table 3 below.

[0067] Table 3. Plugging Performance

[0068] As shown in the table, compared with the comparative example, this application achieves efficient plugging by sequentially injecting a gel foam plugging agent and a foam plugging agent to form an anti-channeling plugging system, thereby expanding the affected area and improving the recovery rate.

[0069] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, this application is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope of this application should be within the protection scope of this application.

Claims

1. A system for preventing cross-contamination and blocking cross-contamination, characterized in that, Including gel foam sealant and foam sealant; The gel foam sealing agent comprises, by mass percentage, the following components: 0.5-1% hydrolyzed polyacrylamide, 0.3-0.8% alkylbenzene sulfonate, 0.5-1% carboxylated gellan gum, 0.1-0.5% crosslinking agent, and the balance being water; the crosslinking agent includes aldehyde crosslinking agents, which are selected from any one or a combination of several of glyoxal, succinaldehyde, glutaraldehyde, adipaldehyde, o-phenylenedialdehyde, azelaic acid, and octanoic acid. The foam sealing agent comprises, by mass percentage, the following components: 0.5-1% fatty alcohol polyoxyethylene ether, 0.5-1% alkyl iminodiacetate or alkyl iminodiapropionate, 0.1-0.3% acylmethyl taurate, and the balance being water; The carboxylated gellan gum is obtained by reacting low-acyl gellan gum, high-acyl gellan gum, and carboxylating reagent; the mass ratio of low-acyl gellan gum to high-acyl gellan gum is (88-95):(5-12); the degree of carboxyl substitution in the carboxylated gellan gum is 0.45-0.55 mmol / g.

2. The anti-channeling and blocking system according to claim 1, characterized in that, The hydrolyzed polyacrylamide has a weight-average molecular weight of 15-20 million and a degree of hydrolysis of 20-30%.

3. The anti-channeling and blocking system according to claim 1, characterized in that, The alkylbenzene sulfonate is selected from C18 to C30 alkylbenzene sulfonates.

4. The anti-channeling and blocking system according to claim 1, characterized in that, The carboxylated gellan gum is further modified using 4,4'-diaminodiphenylamine-2-sulfonic acid. The modification method includes first dispersing the carboxylated gellan gum in an isopropanol solution, adding EDC and NHS for activation, and then adding 4,4'-diaminodiphenylamine-2-sulfonic acid to react and obtain the product.

5. The anti-channeling and blocking system according to claim 4, characterized in that, The mass ratio of the 4,4'-diaminodiphenylamine-2-sulfonic acid to the carboxylated gellan gum is (3-7):

100.

6. The anti-channeling and blocking system according to claim 1, characterized in that, The fatty alcohol polyoxyethylene ether has the following structural formula (I): R-O-[CH2-CH2-O] m -H of formula (I); In formula (I), 9 ≤ m ≤ 16, and R is a C12 to C18 alkyl group.

7. The anti-channeling and blocking system according to claim 1, characterized in that, The acylmethyl taurate is selected from lauroyl methyl taurate and / or cocoyl methyl taurate.

8. A method for preventing gas channeling using the anti-channeling and blocking system according to any one of claims 1-7, characterized in that, include: First, inject the gel foam sealant into the formation to block the large channels, and then inject the foam sealant to block the small channels.

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