Leaking stoppage annulus protection liquid for gas reservoir type gas storage and preparation method of leakage stoppage annulus protection liquid

Abstract

The invention discloses a plugging annulus protection liquid for a gas reservoir type gas storage and a preparation method of the plugging annulus protection liquid. The plugging annulus protection liquid for the gas reservoir type gas storage comprises a main agent system, a plugging capsule, an activating agent and a stabilizing agent, the main agent system mainly comprises a corrosion inhibitor, a bactericide, a deoxidant and a pH value regulator; the plugging capsule mainly comprises a core body and a capsule wall surface; the core body is made of latex particles; the capsule wall surface material is a pH value sensitive material; the activating agent is an electrolyte solution. The plugging annulus protection liquid for the gas reservoir type gas storage can still automatically repair leakage under the condition that an oil casing leaks, the plugging efficiency is improved, the corrosion inhibition efficiency of the plugging annulus protection liquid to the oil casing is higher than 95%, and the corrosion rate is lower than 0.076 mm / a.

Description

Technical Field

[0001] The invention relates to a leak-proof annular space protection liquid for a gas reservoir type gas storage and a preparation method thereof. Background Art

[0002] The gas from the long-distance natural gas pipeline contains about 2% CO 2 , and most gas reservoir-type gas storage reservoirs contain a certain amount of CO 2 The injection and production string will inevitably be exposed to CO 2 The corrosion caused by the injection and production string can lead to failure of the injection and production string in severe cases. Therefore, all gas reservoir-type gas storage facilities adopt the injection and production string structure with a packer, and annular protection fluid is added to the annulus of the tubing and casing to prevent the annulus from contacting the corrosive gas and to balance the upper and lower pressure differences of the production packer. However, when conventional annular protection fluid is added, once the tubing leaks, the corrosive gas enters the annulus, which will cause the annular pressure to increase abnormally, threatening the safe injection and production operation; as the annular pressure increases, a steady stream of corrosive gas enters the annulus, continuously corroding the oil casing, and in severe cases, the casing will fail due to corrosion. This is because the target operating condition of the conventional annular protection fluid design is the condition where the annular integrity is intact and no leakage occurs. Once the corrosive gas enters the annulus, the performance of the annular protection fluid will be reduced or fail, and the protection fluid is very likely to leak, causing the liquid level to drop rapidly and lose its protective effect on the annulus. However, the existing technology mainly focuses on some anti-leakage plugging agents, temporary plugging agents, anti-leakage agents, etc. in ordinary drilling and completion projects, and there is no plugging annulus protection fluid used in gas reservoir type gas storage. Summary of the invention

[0003] The present invention is made in order to enhance the protective effect of the annulus of the oil casing of the gas reservoir type gas storage reservoir so that the annulus protection liquid can still automatically repair the leakage in the event of leakage of the oil casing.

[0004] As a first aspect of the present invention, it relates to a plugging annulus protection fluid for a gas reservoir type gas storage, the plugging annulus protection fluid comprising: a main agent system, a plugging capsule, an activator and a stabilizer;

[0005] The main agent system mainly includes corrosion inhibitor, bactericide, deoxidizer and pH regulator;

[0006] The plugging capsule mainly comprises a core and a capsule wall; the core material is latex particles; the capsule wall material is pH-sensitive material;

[0007] The activator is an electrolyte solution.

[0008] In one or some optional embodiments, the mass percentage of the main agent system is 36-58%; the mass percentage of the plugging capsule is 12-29%; the mass percentage of the activator is 5-10%; and the mass percentage of the stabilizer is 2-5%.

[0009] In one or some optional embodiments, the activator is sodium chloride or magnesium carbonate.

[0010] In one or some optional embodiments, the stabilizer is bentonite or calcium carbonate.

[0011] In one or some optional embodiments, the main agent system mainly includes the following components:

[0012] Corrosion inhibitor, 10-20%wt;

[0013] Bactericide, 3-5%wt;

[0014] Deoxidizer, 5-8%wt;

[0015] pH adjuster, 10-20%wt;

[0016] The balance is water.

[0017] In one or some optional embodiments, the initial pH value of the pH adjuster is 8-9.

[0018] In one or some optional embodiments, the corrosion inhibitor is benzylpyridinium chloride.

[0019] In one or some optional embodiments, the bactericide is dodecyldimethylbenzylammonium chloride.

[0020] In one or some optional embodiments, the oxygen scavenger is dimethyl ketoxime.

[0021] In one or some optional embodiments, the pH adjuster is sodium bicarbonate.

[0022] In one or some optional embodiments, the latex particles are XNBRL latex; and the pH-sensitive material is hydroxypropyl methylcellulose succinate.

[0023] As a second aspect of the present invention, it relates to a method for preparing the above-mentioned plugging annulus protection fluid for gas reservoir type gas storage, the method comprising:

[0024] Prepare the main agent system: mix the corrosion inhibitor, bactericide, deoxidizer, pH adjuster and water evenly;

[0025] Preparation of plugging capsules: mixing latex particles and an organic solution uniformly to obtain a latex particle solution, which is a core material; heating and stirring a pH-sensitive material to obtain a capsule wall material; mixing the core material and the capsule wall material and stirring, and adding a viscosity regulator to the mixed solution to form a capsule system; after the capsule system is naturally cooled, adding a curing agent and stirring, heating, standing to allow the capsule to settle, and filtering to obtain a plugging capsule;

[0026] Preparation of plugging annulus protection fluid: gradually add the main agent system, plugging capsule system, activator and stabilizer, and continue stirring during the addition process until all components are evenly mixed.

[0027] In one or some optional embodiments, the method for preparing the leak-plugging capsule specifically comprises:

[0028] The XNBRL latex and the organic solution are mixed in a mass ratio of 1:3-1:5, and stirred at a speed of 1500-2000 r / min for 20-30 min at 75-90° C. to obtain a core material;

[0029] The hydroxypropyl methylcellulose succinate is stirred at 80-90° C. and a speed of 1800-2400 r / min to obtain a capsule wall material;

[0030] The core material and the wall material are stirred and mixed evenly, and a viscosity regulator is added dropwise to form a capsule system;

[0031] After the capsule system is cooled naturally, a curing agent is added, the mixture is stirred and heated to 70° C., the microcapsules are allowed to settle, and the leak-proof capsules are obtained after filtration.

[0032] In one or some optional embodiments, the organic solvent is hydroxypropyl guar gum or carboxymethyl guar gum.

[0033] In one or some optional embodiments, the viscosity modifier is polyacrylamide or sodium carboxymethyl cellulose.

[0034] In one or some optional embodiments, the curing agent is epoxy resin.

[0035] The leak-proof annular space protection liquid for gas reservoir type gas storage provided by the present invention can automatically seal and repair the leak point when the annular space of the casing leaks, thereby improving the leak-proof efficiency. 2 Corrosive gases enter the annulus, CO 2 Dissolved in water to form carbonic acid, which immediately leads to a decrease in the pH value of the local area of ​​the annulus at the leakage point. In the casing annulus, due to the increase in temperature and pressure, CO 2The solubility is relatively increased, resulting in a decrease in the pH value of carbonic acid under the corresponding working conditions; by optimizing the concentration of the wall capsule material, the critical pH value for the plugging capsule to break can be adjusted. When the pH value in the local area of ​​the leakage point is reduced to the critical pH value for the plugging capsule to break, the plugging capsule breaks, and the latex particles are released into the annular protection fluid, reacting with the electrolyte solution activator. The ions in the electrolyte solution cause a strong hydration of the latex system, reducing the free water molecules in the emulsion, thereby destroying the hydration layer of the latex emulsion, neutralizing the electrical properties of the latex, destroying its double electrical layer structure, causing the latex to become unstable and break, and gelation occurs at the leakage point to achieve the plugging of the leakage point. When the leakage point is plugged, the gas reservoir-type gas storage uses the pH value to adjust the plugging annular protection fluid to restore it to the initial pH value, and establishes a balance again until the next leakage occurs.

[0036] The plugging annulus protection fluid for gas reservoir type gas storage provided by the present invention is prepared by compounding a corrosion inhibitor, a bactericide, a deoxidizer and a pH value adjuster as a main agent system, wherein the corrosion inhibitor can prevent the outer wall of the oil pipe and the inner wall of the casing from being corroded, the bactericide can prevent the outer wall of the oil pipe and the inner wall of the casing from being corroded by bacteria, the deoxidizer can prevent the outer wall of the oil pipe and the inner wall of the casing from being corroded by oxygen, and the pH value adjuster can adjust the initial pH value of the plugging annulus protection fluid. Compounding the corrosion inhibitor, the bactericide and the deoxidizer further enhances the anti-corrosion performance of the plugging annulus protection fluid. The plugging annulus protection fluid for gas reservoir type gas storage has a corrosion inhibition efficiency of more than 95% for the oil casing, and a corrosion rate of less than 0.076 mm / a.

[0037] The plugging annulus protection fluid for gas reservoir type gas storage provided by the present invention has a plugging capsule which will not affect the density, viscosity, antiseptic and bactericidal properties of the annulus protection fluid under normal working conditions, thereby further realizing the protection of the oil casing annulus.

[0038] The plugging annulus protection liquid for gas reservoir type gas storage provided by the present invention has a stabilizer adsorbed on the surface of the plugging capsule, which increases the density of the plugging capsule, avoids stratification of the plugging annulus protection liquid system, increases the stability of the plugging annulus protection liquid system, and the plugging capsules will not stick together.

[0039] Compared with conventional annulus protection fluids, the plugging annulus protection fluid for gas reservoir-type gas storage provided by the present invention can avoid or significantly reduce the risk of abnormal annulus pressure in injection and production wells, extend the well repair-free period, reduce operating costs, avoid injection and production suspension due to well repair operations, ensure injection and production operation efficiency, save well repair costs, and improve the operating efficiency of gas storage, with very significant economic and social benefits. DETAILED DESCRIPTION

[0040] The following is a detailed description of the embodiments of the present invention: The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters for which specific conditions are not specified in the following embodiments are generally based on conventional conditions.

[0041] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0042] Example 1

[0043] Preparation of the main agent system: the corrosion inhibitor, bactericide, deoxidizer, pH regulator with an initial pH value of 8 and water are mixed evenly to obtain the main agent system. Among them: the corrosion inhibitor is 7701-benzylpyridinium chloride (Jiuzhou Biotechnology (Suzhou) Co., Ltd.), and its mass percentage in the main agent system is 10%; the bactericide is dodecyl dimethyl benzyl ammonium chloride (Jinan Quanyan Fine Chemical Co., Ltd.), and its mass percentage in the main agent system is 3%; the deoxidizer is dimethyl ketoxime (Hubei Zhenbo Chemical Co., Ltd.), and its mass percentage in the main agent system is 5%; the pH regulator is sodium bicarbonate, and its mass percentage in the main agent system is 10%; the rest are water.

[0044] Preparation of plugging capsules: XNBRL latex (Shandong Xuchen Chemical Technology Co., Ltd.) and carboxymethyl guar gum are mixed in a mass ratio of 1:3, stirred at 75°C for 20-30min, and the stirrer speed is 1500r / min to obtain a core material; 10% solution mass of hydroxypropyl methylcellulose succinate is selected, heated and stirred, the stirring temperature is 75°C, and the stirrer speed is 1500r / min to form a capsule wall material (the critical pH value of gel breaking can also be adjusted by optimizing the concentration of the wall capsule material); the core material and the capsule wall material are mixed, the stirring speed is adjusted to 1800r / min and the temperature is 75°C, and polyacrylamide (Zibo Lanerqing Polymer Materials Co., Ltd.) is added dropwise to finally form a capsule system; after the capsule system is naturally cooled, a curing agent epoxy resin is added, stirred for 10min, the capsule system is slowly raised from the gelation temperature to 70°C, the microcapsules are allowed to stand for sedimentation, and the plugging capsules used are obtained by filtering.

[0045] Preparation of plugging annular protection fluid for gas reservoir type gas storage: Mix the main agent system and plugging capsules at a mass ratio of 1:0.5, add sodium chloride and bentonite, and continue stirring during the addition of each component until the components are evenly mixed to obtain plugging annular protection fluid for gas reservoir type gas storage. Among them, the mass percentage of sodium chloride in the plugging annular protection fluid is 5%, and the mass percentage of bentonite in the plugging annular protection fluid is 2%.

[0046] After the injection and production string is lowered and the packer is set, the annulus volume is calculated according to the wellbore structure and the size of the injection and production string, and 1.2 times the annulus volume of the gas reservoir type gas storage plugging annulus protection fluid is configured. The positive circulation method is adopted, and the pre-fluid is first injected to flush the annulus. Then the plugging annulus protection fluid for the gas reservoir type gas storage is injected, and finally the displacement fluid is injected until the protection fluid returns to the wellhead annulus. Nitrogen is injected back into the annulus, and a 100m nitrogen column is maintained in the wellhead annulus, and the circulation sleeve is closed.

[0047] According to the weight loss method test, the corrosion inhibition efficiency of the annular space protection liquid of this embodiment on the oil casing is 97%, and the corrosion rate is 0.07mm / a.

[0048] Example 2

[0049] Preparation of the main agent system: the corrosion inhibitor, the bactericide, the deoxidizer, the pH value regulator with an initial pH value of 9 and water are uniformly mixed to obtain the main agent system. The mass percentage of the corrosion inhibitor in the main agent system is 20%, the mass percentage of the bactericide in the main agent system is 5%, the mass percentage of the deoxidizer in the main agent system is 8%, the mass percentage of the pH value regulator in the main agent system is 20%, and the rest is water.

[0050] Preparation of plugging capsules: XNBRL latex and hydroxypropyl guar gum are mixed in a mass ratio of 1:5, stirred at 90°C for 30 minutes, and the stirrer speed is 2000r / min to obtain a core material; 8% hydroxypropyl methylcellulose succinate by mass of the solution is selected, heated and stirred, the stirring temperature is 90°C, and the stirrer speed is 2000r / min to form a capsule wall material (the critical pH value of gel breaking can also be adjusted by optimizing the type and concentration of the wall capsule material); the core material and the capsule wall material are mixed, the stirring speed is adjusted to 2000r / min and the temperature is 80°C, and carboxymethyl cellulose sodium salt (Shanghai Waidian International Trade Co., Ltd.) is added dropwise to finally form a capsule system; after the capsule system is naturally cooled, epoxy resin is added, stirred for 15 minutes, the capsule system is slowly raised from the gelation temperature to 70°C, the microcapsules are allowed to stand for sedimentation, and the plugging capsules used are obtained by filtering.

[0051] Preparation of plugging annular protection fluid for gas reservoir type gas storage: Mix the main agent system and plugging capsules at a mass ratio of 1:0.3, add magnesium carbonate and ultrafine calcium carbonate (diameter 0.08 micron), and continue stirring during the addition of each component until the components are evenly mixed to obtain plugging annular protection fluid for gas reservoir type gas storage. Among them, the mass percentage of magnesium carbonate in the plugging annular protection fluid is 10%, and the mass percentage of ultrafine calcium carbonate in the plugging annular protection fluid is 5%.

[0052] The composition, function and process of other components are the same as those in Example 1 and will not be described in detail here.

[0053] According to the weight loss method test, the corrosion inhibition efficiency of the plugging annulus protection fluid for the gas reservoir type gas storage on the oil casing is 98%, and the corrosion rate is 0.065mm / a.

[0054] Example 3

[0055] Preparation of the main agent system: the corrosion inhibitor, the bactericide, the deoxidizer, the pH value regulator with an initial pH value of 9 and water are uniformly mixed to obtain the main agent system. The mass percentage of the corrosion inhibitor in the main agent system is 15%, the mass percentage of the bactericide in the main agent system is 4%, the mass percentage of the deoxidizer in the main agent system is 6%, the mass percentage of the pH value regulator in the main agent system is 15%, and the rest is water.

[0056] Preparation of plugging capsules: XNBRL latex and hydroxypropyl guar gum are mixed in a mass ratio of 1:5, stirred at 80°C for 25 minutes, and the stirrer speed is 1800 r / min to obtain a core material; 15% solution mass of hydroxypropyl methylcellulose succinate is selected, heated and stirred, the stirring temperature is 80°C, and the stirrer speed is 1800 r / min to form a capsule wall material (the critical pH value of gel breaking can also be adjusted by optimizing the type and concentration of the wall capsule material); the core material and the capsule wall material are mixed, the stirring speed is adjusted to 1800 r / min and the temperature is 60°C, polyacrylamide is added, and finally a capsule system is formed; after the capsule system is naturally cooled, epoxy resin is added, stirred for 15 minutes, the capsule system is slowly raised from the gelation temperature to 70°C, the microcapsules are allowed to stand for sedimentation, and the plugging capsules used are obtained by filtering.

[0057] Preparation of plugging annular protection fluid for gas reservoir type gas storage: Mix the main agent system and plugging capsules at a mass ratio of 1:0.4, add magnesium carbonate and ultrafine calcium carbonate (diameter 0.04 micron), and continue stirring during the addition of each component until the components are evenly mixed to obtain plugging annular protection fluid for gas reservoir type gas storage. Among them, the mass percentage of magnesium carbonate in the plugging annular protection fluid is 8%, and the mass percentage of ultrafine calcium carbonate in the plugging annular protection fluid is 3%.

[0058] The composition, function and process of other components are the same as those in Example 1 and will not be described in detail here.

[0059] According to the weight loss method test, the corrosion inhibition efficiency of the plugging annulus protection fluid for the gas reservoir type gas storage on the oil casing is 97.2%, and the corrosion rate is 0.072mm / a.

[0060] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. The leak-proof annulus protection fluid for gas reservoir type gas storage is characterized by: The plugging annulus protection fluid comprises: a main agent system, a plugging capsule, an activator and a stabilizer; The main agent system mainly includes corrosion inhibitor, bactericide, deoxidizer and pH regulator; The plugging capsule mainly comprises a core and a capsule wall; the core material is latex particles; the capsule wall material is pH-sensitive material; The activator is an electrolyte solution.

2. The plugging annulus protection fluid according to claim 1, characterized in that: The mass percentage of the main agent system is 36-58%; the mass percentage of the plugging capsule is 12-29%; the mass percentage of the activator is 5-10%; and the mass percentage of the stabilizer is 2-5%.

3. The plugging annulus protection fluid according to claim 1, characterized in that: The activator is sodium chloride or magnesium carbonate.

4. The plugging annulus protection fluid according to claim 1, characterized in that: The stabilizer is bentonite or calcium carbonate.

5. The plugging annulus protection fluid according to claim 1, characterized in that: The main agent system mainly includes the following components: Corrosion inhibitor, 10-20%wt; Bactericide, 3-5%wt; Deoxidizer, 5-8%wt; pH adjuster, 10-20%wt; The balance is water.

6. The plugging annulus protection fluid according to claim 1, characterized in that: The initial pH value of the pH adjuster is 8-9.

7. The plugging annulus protection fluid according to claim 1, characterized in that: The corrosion inhibitor is benzylpyridinium chloride.

8. The plugging annulus protection fluid according to claim 1, characterized in that: The bactericide is dodecyl dimethyl benzyl ammonium chloride.

9. The plugging annulus protection fluid according to claim 1, characterized in that: The oxygen scavenger is dimethyl ketoxime.

10. The plugging annulus protection fluid according to claim 1, characterized in that: The pH regulator is sodium bicarbonate.

11. The plugging annulus protection fluid according to claim 1, characterized in that: The latex particles are XNBRL latex; and the pH-sensitive material is hydroxypropyl methylcellulose succinate.

12. A method for preparing the annular space protection fluid for gas reservoir type gas storage according to any one of claims 1 to 11, characterized in that: The method comprises: Prepare the main agent system: mix the corrosion inhibitor, bactericide, deoxidizer, pH adjuster and water evenly; Preparation of plugging capsules: mixing latex particles and an organic solution uniformly to obtain a latex particle solution, which is a core material; heating and stirring a pH-sensitive material to obtain a capsule wall material; mixing the core material and the capsule wall material and stirring, and adding a viscosity regulator to the mixed solution to form a capsule system; after the capsule system is naturally cooled, adding a curing agent and stirring, heating, standing to allow the capsule to settle, and filtering to obtain a plugging capsule; Preparation of plugging annulus protection fluid: gradually add the main agent system, plugging capsule system, activator and stabilizer, and continue stirring during the addition process until all components are evenly mixed.

13. The method according to claim 12, characterized in that The method for preparing the leak-proof capsule specifically comprises: The XNBRL latex and the organic solution are mixed in a mass ratio of 1:3-1:5, and stirred at a speed of 1500-2000 r / min for 20-30 min at 75-90° C. to obtain a core material; The hydroxypropyl methylcellulose succinate is stirred at 80-90° C. and a speed of 1800-2400 r / min to obtain a capsule wall material; The core material and the wall material are stirred and mixed evenly, and a viscosity regulator is added dropwise to form a capsule system; After the capsule system is cooled naturally, a curing agent is added, the mixture is stirred and heated to 70° C., the microcapsules are allowed to settle, and the leak-proof capsules are obtained after filtration.

14. The method according to claim 13, characterized in that The organic solvent is hydroxypropyl guar gum or carboxymethyl guar gum.

15. The method according to claim 13, characterized in that The viscosity modifier is polyacrylamide or sodium carboxymethyl cellulose.

16. The method according to claim 13, characterized in that The curing agent is epoxy resin.