A metal ion crosslinking stabilizer, its preparation method and its application

Abstract

This invention relates to a metal ion crosslinking stabilizer. It primarily addresses the problems of existing gel profile control agents, such as short gelation time, easy damage to medium and low permeability layers during injection, and inability to achieve deep reservoir sealing. Its components and proportions by mass percentage are as follows: 1%-2% retarder, 3%-5% reinforcing agent, 1%-3% regulator, 4%-5% ion stabilizer, 1%-2% water purifier, and the balance being water. Preparation method: 1) Add the ion stabilizer and reinforcing agent to water according to the proportions and mix evenly in a 45°C water bath; 2) Add the regulator to the mixture and mix evenly; 3) Add the retarder and maintain the water bath for 2-3 hours; 4) Add the water purifier to obtain the target product. This metal ion crosslinking stabilizer can be used as an auxiliary additive component in the formulation of polyacrylamide ion crosslinking profile control agent systems. It can prolong the gelation time of the profile control agent, ensure the gel viscosity of the profile control agent, improve the stability of the profile control agent, and achieve effective sealing of the system.

Description

Technical fields:

[0001] This invention relates to the field of oilfield chemistry, and in particular to a metal ion crosslinking stabilizer, its preparation method, and its application. Background technology:

[0002] Commonly used crosslinking agent systems often employ metal complexation crosslinking, and the gel viscosity is related to the complexing ability of metal ions. There is a contradictory relationship between gel viscosity and gelation time in this system: on the one hand, extending the gelation time and slowing the release rate of the effective components of the crosslinking agent is beneficial for the profile control agent to reach deeper formations during injection, achieving the goal of deep profile control; on the other hand, a longer gelation time also leads to prolonged exposure of the effective components of the crosslinking agent to high temperature and aerobic environment, causing complete or partial loss of crosslinking properties (deactivation). This significantly affects the subsequent gel viscosity of the profile control agent, ultimately impacting the profile control construction effect. Summary of the Invention:

[0003] The purpose of this invention is to overcome the problems of existing common crosslinking agents in oilfields, such as short gelation time, easy damage to medium and low permeability layers during injection, and inability to achieve deep reservoir sealing. This invention provides a metal ion crosslinking stabilizer. This metal ion crosslinking stabilizer can be used as an auxiliary additive in the formulation of polyacrylamide ion crosslinking profile control agent systems, extending the gelation time of the profile control agent, ensuring its gelation viscosity, improving its stability, and achieving effective sealing of the system. This invention also provides a method for preparing the metal ion crosslinking stabilizer and its application.

[0004] To achieve the above objectives, the first aspect of the present invention provides a metal ion crosslinking stabilizer, wherein the components and proportions are as follows by mass percentage: 1%-2% retarder, 3%-5% reinforcing agent, 1%-3% regulator, 4%-5% ion stabilizer, 1%-2% water purifier, and the remainder is water.

[0005] Preferably, the retarder is citric acid, which has a large coordination constant, strong chelation coordination, and strong chelation ability, thus playing a role in complexing crosslinking ions and delaying the gelation time of the system.

[0006] Preferably, the reinforcing agent is at least one of the following nonionic surfactants: polyoxyethylene octylphenol ether-10 (OP-10), fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene (10) ester, fatty amine polyoxyethylene ether (leveling agent AN), alkylolamide polyoxyethylene ether, block polyoxyethylene-polyoxypropylene ether, alkylolamide, etc.

[0007] Preferably, the regulator is triethanolamine, or it can be a weakly alkaline substance such as disodium hydrogen phosphate.

[0008] Preferably, the ionic stabilizer is potassium sorbate, but it can also be a preservative such as benzoic acid, sorbic acid, dehydroacetic acid, parabens, sodium diacetate, calcium propionate, or sodium lactate.

[0009] Preferably, the water purification agent is polyaluminum chloride, but it can also be iron-free water purification agents such as basic aluminum chloride or aluminum sulfate.

[0010] The retarder is citric acid, which plays a role in complexing cross-linking ions and delaying the gelation time of the system.

[0011] The reinforcing agent, after the system gels, plays a role in increasing the viscosity of the system in the later stages;

[0012] The regulator keeps the system environment in a neutral to weakly alkaline state, ensuring the gelation effect of the system;

[0013] The ionic stabilizer serves to stabilize the viscosity of the system;

[0014] The water purification agent, as a wastewater purification agent, plays a role in purifying wastewater and ensuring the gelling performance of the system.

[0015] Another aspect of the present invention provides a method for preparing a metal ion crosslinking stabilizer, comprising the following steps:

[0016] (1) Add the ion stabilizer and reinforcing agent to water in proportion and mix them evenly under water bath conditions of 45℃-60℃;

[0017] (2) While stirring, add the regulator to the container containing the mixture and mix thoroughly.

[0018] (3) Add a retardant and maintain the water bath for 2-3 hours;

[0019] (4) Finally, add water purification agent to obtain the target product metal ion crosslinking stabilizer.

[0020] A third aspect of this invention provides the application of metal ion crosslinking stabilizers in deep oilfield plugging control. Specifically, it includes the following steps:

[0021] 1) The metal ion crosslinking stabilizer prepared in this invention is used in combination with the crosslinking agent in the profile control agent;

[0022] 2) The amount of the metal ion crosslinking stabilizer used is determined according to the on-site requirements and the metal ion content in the crosslinking agent;

[0023] The specific determination method is as follows:

[0024] The higher the metal ion content in the crosslinking agent, the higher the concentration of the metal ion crosslinking retarder should be.

[0025] The longer the gelation time required on site, the higher the concentration of the metal ion crosslinking retarder should be.

[0026] 3) The preparation of the profile control agent used on-site should be based on 0.1%-0.4% polyacrylamide,

[0027] Formulated with 0.25%-1% Cr3+ crosslinking agent and 1-2% metal ion crosslinking retarder, a gelation time of 30 days can be achieved.

[0028] Compared with the above-mentioned background technology, the present invention has the following beneficial effects:

[0029] The metal ion crosslinking stabilizer described in this invention has a good shielding effect on the carboxylic acid (ion) groups in the system, ultimately achieving a better delay in the crosslinking effect of the metal ion crosslinking system. This metal ion crosslinking stabilizer can be used as an adjuvant in deep profile control agents in deep oilfield plugging processes, further delaying the gelation time of the system, enhancing the performance of deep profile control agents, and expanding the application range of deep profile control agents.

[0030] The metal ion crosslinking stabilizer of this invention utilizes the chelating coordination effect of the retarder to form a relatively stable structure with metal ions, releasing the metal ions at a slow rate, thus slowing down the gelation rate of the system and achieving the purpose of delaying crosslinking. The addition of reinforcing agents and regulators to the system allows the reinforcing agents, with the assistance of the regulators, to form spherical micelles in water linked to -COOH groups via hydrogen bonds, significantly increasing the final gelation viscosity of the profile control system. Simultaneously, the addition of stabilizers and water purification agents prevents or slows down degradation of the system under complex geological conditions and various component conditions, maintaining the system without gelation and preserving a high viscosity over a long period. Therefore, the metal ion crosslinking stabilizer of this invention can, on the one hand, extend the gelation time of the profile control system, transporting the system to deeper formations to achieve deep profile control; on the other hand, it can ensure the gelation viscosity and stability of the profile control system, achieving effective sealing. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a schematic diagram illustrating the mechanism by which the stabilizer of the present invention "binds" the -COOH groups on hydrolyzed polyacrylamide through hydrogen bonding;

[0033] Figure 2 A comparison chart of the gelling properties of the profile control system without the stabilizer of the present invention and with the stabilizer of the present invention;

[0034] Figure 3This is a comparison chart of the gelling properties of the profile control system prepared with citric acid and salicylic acid as retardants in the stabilizer of the present invention.

[0035] Figure 4 This is a comparison chart showing the gelling performance of the crosslinking agent under different dosages of the stabilizer of the present invention. Detailed implementation method:

[0036] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0037] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0038] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0039] A metal ion crosslinking stabilizer, the components and their proportions by mass percentage are as follows: 1%-2% retarder, 3%-5% reinforcing agent, 1%-3% regulator, 4%-5% ion stabilizer, 1%-2% water purification agent, and the balance being water.

[0040] The retarder is citric acid.

[0041] The reinforcing agent is OP-10, or it can be a nonionic surfactant such as fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene (10) ester, fatty amine polyoxyethylene ether (leveling agent AN), alkylolamide polyoxyethylene ether, block polyoxyethylene-polyoxypropylene ether, alkylolamide, etc.

[0042] The regulator is triethanolamine, or it can be a weakly alkaline substance such as disodium hydrogen phosphate.

[0043] The ion stabilizer is potassium sorbate, but it can also be a preservative such as benzoic acid, sorbic acid, dehydroacetic acid, parabens, sodium diacetate, calcium propionate, or sodium lactate.

[0044] The water purification agent is polyaluminum chloride, but it can also be iron-free water purification agents such as basic aluminum chloride or aluminum sulfate.

[0045] A method for preparing a metal ion crosslinking stabilizer includes the following steps:

[0046] Another aspect of the present invention provides a method for preparing a metal ion crosslinking stabilizer, comprising the following steps:

[0047] (1) Add the ion stabilizer and reinforcing agent to water in proportion and mix them evenly under water bath conditions of 45℃-60℃;

[0048] (2) While stirring, add the regulator to the container containing the mixture and mix thoroughly.

[0049] (3) Add a retardant and maintain the water bath for 2-3 hours;

[0050] (4) Finally, add water purification agent to obtain the target product metal ion crosslinking stabilizer.

[0051] This invention also provides the application of metal ion crosslinking stabilizers in deep oilfield plugging control. Specifically, it includes the following steps:

[0052] 1) The metal ion crosslinking stabilizer prepared in this invention is used in combination with the crosslinking agent in the profile control agent;

[0053] 2) The amount of the metal ion crosslinking stabilizer used is determined based on on-site requirements and the metal ion content in the crosslinking agent; the specific determination method is as follows:

[0054] The higher the metal ion content in the crosslinking agent, the higher the concentration of the metal ion crosslinking retarder should be.

[0055] The longer the gelation time required on site, the higher the concentration of the metal ion crosslinking retarder should be.

[0056] 3) The profile control agent used on site is prepared by using 0.1%-0.4% polyacrylamide, 0.25%-1% Cr3+ crosslinking agent, and 1-2% metal ion crosslinking retarder, which can achieve a gelation time of 30 days.

[0057] like Figure 1 As shown, the working principle of the metal ion crosslinking retarder of the present invention is as follows:

[0058] A comparison of the retardation effects of different organic acids and regulators on the HPAM / Cr(C3H5O3)3 gel profile control system reveals that, since the "shielding" of metal ions is achieved through chelation, when the coordination effect of organic acids on metal ions is weak, they are difficult to "bind" the metal ions, leading to rapid cross-linking reactions and poor retardation of cross-linking. Conversely, when the coordination effect of organic acids on metal ions is strong, a large number of metal ions are completely "bound" and cannot be released, resulting in insufficient cross-linking and a very weak gel viscosity. However, when the regulator "shields" the -COO- groups through hydrogen bonding with the -COOH groups, the interaction between the two is moderate, and the equilibrium shift caused by the interconversion of -COO- groups and -COOH groups results in a better retardation effect on cross-linking than organic acids, with almost no impact on the final viscosity of the system. The metal ion cross-linking stabilizer described in this invention has a good shielding effect on the carboxylic acid (ion) groups in the system, ultimately achieving a better retardation effect on cross-linking.

[0059] Example 1:

[0060] In this embodiment, the stabilizer K-001 is composed of the following components by weight percentage: 4% potassium sorbate, 3% OP-10, 1% triethanolamine, 1% citric acid, 1% polyaluminum chloride, and the balance being water. The specific preparation process is as follows:

[0061] (1) Place the three-necked flask in a constant temperature water bath, add the corresponding mass of water (weigh 90g using an electronic balance) to the three-necked flask, heat the constant temperature water bath to 45°C, put a thermometer and an electric stirrer into the three-necked flask, and after the temperature reaches 45°C, add 4g of potassium sorbate and 3g of OP-10, and stir and mix evenly using an electric stirrer.

[0062] (2) While stirring, add 1g of triethanolamine to the three-necked flask and stir with an electric stirrer until well mixed.

[0063] (3) While stirring, add 1g of citric acid to the three-necked flask and stir with an electric stirrer for 2-3 hours;

[0064] (4) Finally, add 1g of polyaluminum chloride to the three-necked flask and stir and mix evenly with an electric stirrer to obtain the target product K-001.

[0065] Application Example 1

[0066] After preparing the profile control stabilizer K-001, it was compounded with a crosslinking agent and polyacrylamide to obtain profile control agent systems T-001 and T-002. Profile control agent system T-001 contains the profile control stabilizer K-001; while T-002 does not contain the profile control stabilizer K-001. The specific steps are as follows:

[0067] (1) Prepare 0.1% polyacrylamide in beaker 1;

[0068] (2) Add 0.25% Cr to beaker 1. 3+ The crosslinking agent and 1% of the stabilizer K-001 are stirred thoroughly to obtain the profile control agent system T-001.

[0069] (3) Prepare 0.1% polyacrylamide in beaker 2;

[0070] (4) Add 0.25% Cr to beaker 2. 3+ The crosslinking agent is stirred thoroughly to obtain the profile control agent system T-002.

[0071] A comparison of the gelling properties of the profile control system without and with the stabilizer of this invention is shown below. Figure 2 .

[0072] like Figure 2As shown in the experimental results, the introduction of the stabilizer K-001 of the present invention into the profile control agent system effectively prolongs the gelation time of the profile control agent. At the same time, since the stabilizer K-001 of the present invention contains a reinforcing agent, it plays a role in increasing the viscosity of the system after gelation. Therefore, the final gel strength of the gel system with stabilizer K-001 is greater than that of the gel system without stabilizer K-001.

[0073] Comparative Example 1

[0074] In this embodiment, the stabilizer K-002 is composed of the following components by weight percentage: 4% potassium sorbate, 3% OP-10, 1% triethanolamine, 1% salicylic acid, 1% polyaluminum chloride, and the balance being water.

[0075] The specific preparation process is as follows:

[0076] (1) Place the three-necked flask in a constant temperature water bath, add the corresponding mass of water (weigh 90g using an electronic balance) to the three-necked flask, heat the constant temperature water bath to 45°C, put a thermometer and an electric stirrer into the three-necked flask, and after the temperature reaches 45°C, add 4g of potassium sorbate and 3g of OP-10, and stir and mix evenly using an electric stirrer.

[0077] (2) While stirring, add 1g of triethanolamine to the three-necked flask and stir with an electric stirrer until well mixed.

[0078] (3) While stirring, add 1g of salicylic acid to the three-necked flask and stir with an electric stirrer for 2-3 hours;

[0079] (4) Finally, add 1g of polyaluminum chloride to the three-necked flask and stir with an electric stirrer until the target product is obtained.

[0080] Application Example 2

[0081] After preparing the profile control stabilizer K-002, it was compared with the profile control stabilizer K-001 in Example 1. The profile control systems T-003 and T-004 were obtained by compounding with a crosslinking agent and polyacrylamide. In the profile control system T-003, the retardant in the stabilizer is citric acid; while in the profile control system T-004, the retardant in the stabilizer is salicylic acid.

[0082] (1) Prepare 0.1% polyacrylamide in beaker 3;

[0083] (2) Add 0.25% Cr to beaker 3. 3+ The crosslinking agent and 1% stabilizer K-001 are stirred thoroughly to obtain the profile control agent system T-003.

[0084] (3) Prepare 0.1% polyacrylamide in beaker 4;

[0085] (4) Add 0.25% Cr to beaker 4. 3+ The crosslinking agent and 1% stabilizer K-002 are thoroughly stirred to obtain the profile control agent system T-004.

[0086] A comparison of the gelling properties of profile control systems formulated with citric acid and salicylic acid as retarders is shown in the figure. Figure 3 .

[0087] like Figure 3 As shown in the experimental results, when the retarder in the stabilizer is salicylic acid, its coordination constant is small and its chelating ability is weak, resulting in a short gelation time for the profile control agent system. However, when the retarder is citric acid, its chelating ability is strong, resulting in a long gelation time for the profile control agent system.

[0088] Application Example 3

[0089] In this embodiment, the stabilizer K-001 was selected in different proportions and compounded with crosslinking agent and polyacrylamide to obtain profile control agent systems T-005, T-006 and T-007.

[0090] Its preparation process is as follows:

[0091] (1) Prepare 0.1% polyacrylamide in beaker 5;

[0092] (2) Add 0.25% Cr to beaker 5. 3+ The crosslinking agent and 0.5% of the stabilizer K-001 are thoroughly stirred to obtain the profile control agent system T-005.

[0093] (3) Prepare 0.1% polyacrylamide in beaker 6;

[0094] (4) Add 0.25% Cr to beaker 6. 3+ The crosslinking agent and 0.8% of the stabilizer K-001 are thoroughly stirred to obtain the profile control agent system T-006.

[0095] (5) Prepare 0.1% polyacrylamide in beaker 7;

[0096] (6) Add 0.25% Cr to beaker 7. 3+ The crosslinking agent and 1.0% of the stabilizer K-001 are stirred thoroughly to obtain the profile control agent system T-007.

[0097] Comparison of gelling properties of crosslinking agents under different dosages of stabilizer is shown in the figure. Figure 4 .

[0098] like Figure 4As shown in the experimental results, with the increase of the amount of stabilizer, the gelation time of the profile control agent gradually increases, and the final gelation viscosity remains basically unchanged. Therefore, by introducing the stabilizer K-001 of the present invention, a series of profile control agent systems with different gelation times can be formed to meet the sealing needs of different reservoirs.

[0099] Field application examples

[0100] After preparing the profile control agent K-001, a crosslinking agent and polyacrylamide are used to compound it to obtain the profile control agent system. A mobile mixing device is used for on-site application. When preparing the profile control agent on-site, the three chemical agents are added to the preparation tank in the order of polymer, crosslinking agent, and profile control agent using an ejector, stirring continuously. After adding all the chemicals, water is added to bring the volume to 15m³. 3 Stir for 30 minutes, then pour into a curing tank and cure for 2 hours. Stir again for 10 minutes before injection. The specific construction steps are as follows:

[0101] (1) Prepare 0.1% polyacrylamide, typically in a 15m³ container. 3 First, fill the tank halfway with water, then add 15 kg of polyacrylamide while stirring.

[0102] (2) Add 0.25% Cr 3+ Add crosslinking agent (37.5 kg) while stirring;

[0103] (3) Add 1% of stabilizer K-001 (150kg) while stirring;

[0104] (4) Add water to bring the volume to 15m. 3 Stir for 30 minutes. Then pour into a curing tank and cure for 2 hours. Stir for another 10 minutes before pouring.

[0105] (5) Finally, inject it into the formation.

[0106] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of them. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. Although the specific embodiments of the present invention have been described above, they are not intended to limit the protection scope of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A metal ion crosslinking stabilizer, characterized in that: Its components and proportions by mass percentage are as follows: 1%-2% retardant, 3%-5% enhancer, 1%-3% regulator, 4%-5% ion stabilizer, 1%-2% water purifier, and the remainder is water; The retardant is citric acid; the reinforcing agent is at least one of polyoxyethylene octylphenol ether-10, fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene-10-ester, fatty amine polyoxyethylene ether, alkyl alcohol amide polyoxyethylene ether, block polyoxyethylene-polyoxypropylene ether, or alkyl alcohol amide. The regulator is a weakly basic substance; the weakly basic substance is triethanolamine; The ion stabilizer is potassium sorbate; The water purification agent is an iron-free water purification agent; the iron-free water purification agent is at least one of polyaluminum chloride, basic aluminum chloride, or aluminum sulfate.

2. A method for preparing a metal ion crosslinking stabilizer as described in claim 1, characterized in that: Includes the following steps: (1) Add the ion stabilizer and reinforcing agent to water in proportion and mix them evenly in a water bath at 45℃-60℃; (2) While stirring, add the regulator to the container containing the mixture and mix thoroughly. (3) Add a retardant and maintain the water bath for 2-3 hours; (4) Finally, add water purification agent to obtain the target product metal ion crosslinking stabilizer.

3. The application of the metal ion crosslinking stabilizer according to claim 1 in deep oilfield plugging.

4. The application according to claim 3, characterized in that: The crosslinking agent used in the field is prepared by using 0.1%-0.4% polyacrylamide, 0.25%-1% Cr3+ crosslinking agent, and 1-2% metal ion crosslinking retarder, which can achieve a gelation time of 30 days.

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