Oxygen-reduction air foam flooding corrosion inhibitor and preparation method thereof

Abstract

The invention belongs to the field of oilfield chemistry, and particularly discloses a corrosion inhibitor for oxygen reduction air foam flooding and a preparation method thereof.The preparation method comprises the steps that in a catalyst and pressurized environment, a methanol solution of melamine and sulfydryl carboxylic acid are subjected to an amidation reaction, and the sulfydryl-containing corrosion inhibitor for oxygen reduction air foam flooding is synthesized; as the corrosion inhibitor contains more nitrogen atoms, the nitrogen atoms can be effectively adsorbed on the metal surface, meanwhile, the corrosion inhibitor contains a certain amount of sulfydryl which consumes oxygen elements around the metal surface to a certain extent, and the sulfydryl can also be adsorbed on the metal surface to form a synergistic effect with the nitrogen atoms, the corrosion inhibitor can effectively reduce oxygen corrosion in air foam flooding, and the corrosion inhibitor has a good application prospect. When the addition amount is 0.02-0.05%, the corrosion inhibition efficiency can reach 85% or above, the feeding amount is small in the actual use process, the corrosion inhibition effect is remarkable, and the requirements in the air foam flooding application process can be completely met.

Description

Technical Field

[0001] The present invention belongs to the field of oilfield chemistry, and particularly relates to a corrosion inhibitor for oxygen-reduced air foam flooding and a preparation method thereof. Background Art

[0002] Gas flooding is the main technical direction for enhancing the recovery rate of low-permeability tight oil. Among them, air flooding is an important part of gas flooding. The air foam flooding technology combines air flooding and foam flooding to enhance the recovery rate by adding a foaming agent when injecting air, and it is one of the promising means for enhancing the recovery rate in ultra-low permeability reservoirs. Oxygen corrosion is the main factor restricting the application and popularization of air foam flooding technology, and oxygen reduction can reduce the corrosion rate. The corrosion rate of N80 steel during air foam flooding decreases non-linearly with the decrease of the oxygen content in the air, but the corrosion rate cannot be controlled below the standard of 0.076 mm / a. Summary of the Invention

[0003] The purpose of the present invention is to provide a corrosion inhibitor for oxygen-reduced air foam flooding and a preparation method thereof to solve the problem of oxygen corrosion hazards in air foam flooding technology.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention provides a corrosion inhibitor for oxygen-reduced air foam flooding, and the corrosion inhibitor includes: melamine and mercapto carboxylic acid;

[0006] Wherein, the molar ratio of melamine to mercapto carboxylic acid is 1:(1-3);

[0007] The structural formula of the corrosion inhibitor for oxygen-reduced air foam flooding is:

[0008]

[0009] Wherein, R is a mercapto functional group, and the structural formula of R is:

[0010] Further, the corrosion inhibitor for oxygen-reduced air foam flooding is prepared by reacting under pressurization, normal temperature and catalyst conditions, and the mass of the catalyst is 0.01%-0.05% of the mass of melamine.

[0011] Further, the melamine is specifically a 20% methanol solution of melamine.

[0012] Further, the carbon chain length of the mercapto carboxylic acid is 2-7.

[0013] Further, the catalyst is palladium or rhodium or a molecular sieve mainly composed of palladium or rhodium.

[0014] Further, in the structural formula of the corrosion inhibitor for oxygen-reduced air foam flooding, R is randomly substituted for 1-3.

[0015] In a second aspect, the present invention provides a preparation method of a corrosion inhibitor for oxygen-reduced air foam flooding, and the method is used to prepare the corrosion inhibitor for oxygen-reduced air foam flooding described in any one of the above.

[0016] The method includes:

[0017] Prepare a methanol solution of melamine, put the methanol solution of melamine and mercapto carboxylic acid as raw materials into a reaction kettle, stir, and carry out amidation reaction under the conditions of a catalyst, pressure, and normal temperature to generate a corrosion inhibitor for oxygen-reduced air foam flooding.

[0018] Further, the pressure range of the pressurized environment is 1 Mpa - 2 Mpa.

[0019] Further, the stirring speed is 500 r / min - 2000 r / min.

[0020] Further, the amidation reaction is carried out at normal temperature for 4 - 6 hours.

[0021] The present invention has at least the following beneficial effects:

[0022] In the present invention, amidation reaction is carried out on the methanol solution of melamine and mercapto carboxylic acid in a catalyst and pressurized environment to synthesize a corrosion inhibitor for oxygen-reduced air foam flooding containing mercapto; due to the relatively large number of nitrogen atoms in this corrosion inhibitor, it can be effectively adsorbed on the metal surface. At the same time, it contains a certain amount of mercapto, which can consume a certain amount of oxygen element around the metal surface. At the same time, the mercapto can also be adsorbed on the metal surface, forming a synergistic effect with the nitrogen atoms. It can effectively reduce oxygen corrosion in air foam flooding. When the addition amount is 0.02 - 0.05%, the corrosion inhibition efficiency can reach more than 85%. During actual use, the feeding amount is small, and the corrosion inhibition effect is remarkable, which can fully meet the requirements during the application of air foam flooding. Specific Embodiments

[0023] The present invention will be described in detail below with reference to the embodiments. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0024] The following detailed descriptions are all exemplary descriptions, aiming to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0025] Example 1

[0026] An inhibitor for oxygen-reduced air foam flooding, the inhibitor comprising: melamine, mercapto carboxylic acid and a catalyst, the molar ratio of melamine to mercapto carboxylic acid being 1:(1-3); the mass of the catalyst being 0.01%-0.05% of the mass of melamine;

[0027] The structural formula of the inhibitor for oxygen-reduced air foam flooding is:

[0028]

[0029] Among them, R replaces 1-3 of them according to actual needs, R is a mercapto functional group, and the structural formula of R is:

[0030]

[0031] Among them, the value of n is 0-5.

[0032] Melamine is specifically a 20% methanol solution of melamine; the carbon chain length of mercapto carboxylic acid is 2-7;

[0033] The catalyst is palladium, rhodium and molecular sieves mainly composed of them.

[0034] Example 2

[0035] A preparation method of an inhibitor for oxygen-reduced air foam flooding, comprising:

[0036] Prepare a 20% methanol solution of melamine, put the 20% methanol solution of melamine and mercapto carboxylic acid as raw materials into a reaction kettle, add a catalyst at the same time, then pressurize to 1 Mpa - 2 Mpa, and carry out an amidation reaction at a stirring speed of 500 r / min - 2000 r / min at room temperature for 4-6 hours to generate a mercapto melamine amidation compound, that is, an inhibitor for oxygen-reduced air foam flooding.

[0037] Example 3

[0038] Prepare a 20% methanol solution of melamine, weigh 63 grams of melamine solution (the amount of melamine is 12.6 grams, which is 0.1 mol), pour it into a high-temperature and high-pressure reaction kettle, and at the same time add 0.0013 grams of palladium to the reaction kettle, start stirring, the rotation speed is 500 r / min, and add 0.1 mol of mercaptoacetic acid. Fill with nitrogen, pressurize to 1 MPa, react for 4 hours, and release the pressure to obtain the product as an inhibitor.

[0039] Evaluate the inhibitor, specifically:

[0040] S1: Polish the N80 steel standard coupon with metallographic sandpaper, then clean it with absolute ethanol, and weigh it after drying;

[0041] S2: Prepare the corrosion liquid: 5% sodium chloride, 0.2% magnesium chloride, 0.6% sodium sulfate, 0.4% calcium chloride, and the rest is water. Prepare 1 L and add it to the autoclave.

[0042] S3: Fix the N80 standard coupon on the bracket inside the autoclave, and fill the autoclave with air containing 2% oxygen to the experimental pressure.

[0043] S4: Heat to the experimental temperature, turn on the stirrer inside the autoclave, and maintain the stirring rate at 500 r / min. The duration of each weight loss experiment is 120 h.

[0044] S5: After the experiment, stop heating and stirring, take out the coupon. Put it into the de-filming liquid (hydrochloric acid + hexamethylene) to remove the surface corrosion products, then wipe it with acetone and absolute ethanol, dry it and weigh it to test the corrosion rate. The corrosion rate calculation formula is:

[0045]

[0046] In the evaluation, add the corrosion inhibitor in step S2, and the evaluation results at different temperatures are as follows:

[0047] Table 1 Evaluation results of the corrosion inhibitor in Example 3

[0048]

[0049] It can be seen from the test data in the above table that under the same conditions, the corrosion inhibitor of the present invention has certain corrosion inhibition performance in an oxygen medium environment, and can meet the requirement that the corrosion rate does not exceed 0.076 mm / a specified by the industry at different temperatures with a certain dosage.

[0050] Example 4

[0051] Prepare a 20% methanol solution of melamine. Weigh 63 g of the melamine solution (the amount of melamine is 12.6 g, which is 0.1 mol), pour it into a high-temperature and high-pressure reaction kettle, and at the same time add 0.0013 g of palladium to the reaction kettle. Start stirring at a speed of 500 r / min, and add 0.3 mol of mercaptoacetic acid. Fill with nitrogen, pressurize to 1 MPa, react for 4 hours, and release the pressure to obtain the product as the corrosion inhibitor.

[0052] The evaluation method is carried out according to that in Example 3. In the evaluation, add the product generated in this example, and the evaluation results at different temperatures are as follows:

[0053] Table 2 Evaluation results of the corrosion inhibitor in Example 4

[0054]

[0055]

[0056] As can be seen from the test data in the above table, under the same conditions, the corrosion inhibitor of the present invention has certain corrosion inhibition performance in an oxygen medium environment, and can meet the requirement that the corrosion rate does not exceed 0.076 mm / a specified by the industry at different temperatures with a certain dosage.

[0057] Example 5

[0058] Prepare a 20% methanol solution of melamine. Weigh 63 grams of the melamine solution (the amount of melamine is 12.6 grams, which is 0.1 mol), pour it into a high-temperature and high-pressure reaction kettle, and at the same time add 0.0013 grams of palladium into the reaction kettle. Start stirring at a speed of 500 r / min, and add 0.2 mol of mercaptoacetic acid. Fill with nitrogen, pressurize to 1 MPa, react for 4 hours, relieve the pressure, and obtain the product as the corrosion inhibitor.

[0059] The evaluation method is carried out according to that in Example 3. In the evaluation, the product generated in this example is added, and the evaluation results at different temperatures are as follows:

[0060] Table 3 Evaluation Results of the Corrosion Inhibitor in Example 5

[0061]

[0062] As can be seen from the test data in the above table, under the same conditions, the corrosion inhibitor of the present invention has certain corrosion inhibition performance in an oxygen medium environment, and can meet the requirement that the corrosion rate does not exceed 0.076 mm / a specified by the industry at different temperatures with a certain dosage.

[0063] Example 6

[0064] Prepare a 20% methanol solution of melamine. Weigh 63 grams of the melamine solution (the amount of melamine is 12.6 grams, which is 0.1 mol), pour it into a high-temperature and high-pressure reaction kettle, and at the same time add 0.006 grams of palladium into the reaction kettle. Start stirring at a speed of 2000 r / min, and add 0.2 mol of mercaptoacetic acid. Fill with nitrogen, pressurize to 1 MPa, react for 6 hours, relieve the pressure, and obtain the product as the corrosion inhibitor.

[0065] The evaluation method is carried out according to that in Example 3. In the evaluation, the product generated in this example is added, and the evaluation results at different temperatures are as follows:

[0066] Table 4 Evaluation Results of the Corrosion Inhibitor in Example 6

[0067]

[0068] As can be seen from the test data in the above table, under the same conditions, the corrosion inhibitor of the present invention has certain corrosion inhibition performance in an oxygen medium environment, and can meet the requirement that the corrosion rate does not exceed 0.076 mm / a specified by the industry at different temperatures with a certain dosage.

[0069] As is known to those skilled in the art, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent substitutions, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. An inhibitor for oxygen-reduced air foam flooding, characterized in that, The corrosion inhibitor includes: melamine and mercapto carboxylic acid; wherein, the molar ratio of melamine to mercapto carboxylic acid is 1:(1-3); The structural formula of the corrosion inhibitor for oxygen-reduced air foam flooding is: Among them, R is a mercapto functional group, and the structural formula of R is:

2. The corrosion inhibitor for oxygen-reduced air foam flooding according to claim 1, characterized in that The corrosion inhibitor for oxygen-reduced air foam flooding is prepared by reacting under the conditions of pressurization, normal temperature and catalyst, and the mass of the catalyst is 0.01%-0.05% of the mass of melamine.

3. The corrosion inhibitor for oxygen-reduced air foam flooding according to claim 1, characterized in that, The melamine is specifically a 20% methanol solution of melamine.

4. An inhibitor for oxygen-reduced air foam flooding according to claim 1, characterized in that, The carbon chain length of the mercapto carboxylic acid is 2-7.

5. An inhibitor for oxygen-reduced air foam flooding according to claim 2, characterized in that, The catalyst is palladium or rhodium or a molecular sieve mainly composed of palladium or rhodium.

6. The corrosion inhibitor for oxygen-reduced air foam flooding according to claim 1, characterized in that, In the structural formula of the corrosion inhibitor for oxygen-reduced air foam flooding, R is randomly substituted 1-3 times.

7. A preparation method of a corrosion inhibitor for oxygen-reduced air foam flooding, the method is used to prepare the corrosion inhibitor for oxygen-reduced air foam flooding according to any one of claims 1-7, and is characterized in that the method includes: Preparing a methanol solution of melamine, putting the methanol solution of melamine and mercapto carboxylic acid as raw materials into a reaction kettle, stirring, and carrying out amidation reaction under the conditions of catalyst, pressurization and normal temperature to generate a corrosion inhibitor for oxygen-reduced air foam flooding.

8. The preparation method of an oxygen-reduced air foam flooding corrosion inhibitor according to claim 1, characterized in that The pressure range of the pressurized environment is 1 Mpa - 2 Mpa.

9. The preparation method of a corrosion inhibitor for oxygen-reduced air foam flooding according to claim 1, characterized in that, The stirring speed is 500 r / min - 2000 r / min.

10. The preparation method of a corrosion inhibitor for oxygen-reduced air foam flooding according to claim 1, characterized in that, The amidation reaction is carried out at normal temperature for 4-6 hours.

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