High-temperature-resistant corrosion inhibitor for high-density completion fluid as well as preparation method and application of high-temperature-resistant corrosion inhibitor

Abstract

The invention discloses a high-temperature-resistant corrosion inhibitor for high-density completion fluid as well as a preparation method and application of the high-temperature-resistant corrosion inhibitor. The corrosion inhibitor provided by the invention is composed of a sulfur-containing organic amine compound and nonyl imidazoline. The invention further provides a preparation method of the corrosion inhibitor and application of the corrosion inhibitor in a high-temperature deep well. The corrosion inhibitor provided by the invention has relatively strong high-temperature resistance and corrosion inhibition performance, and can effectively inhibit corrosion of high-density well completion fluid to underground steel under high-temperature and high-pressure conditions, so that well completion operation accidents are reduced, and the well completion efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the field of petroleum exploration and development, and specifically relates to a high-temperature corrosion inhibitor for high-density completion fluid and a preparation method and application thereof. Background Art

[0002] With the continuous advancement of oil extraction technology, the development of high-temperature deep wells will gradually increase. In order to balance the requirements of formation and well control, a high-density completion fluid must be used for high-temperature deep well completion. At present, solid-free high-density completion fluids generally use soluble salts such as potassium formate, sodium formate, calcium chloride, etc. added to water to increase the density. However, high-density brine has different degrees of corrosion on downhole tubing, casing and tools at high temperatures, especially under the conditions of high temperature and high density in deep wells. The corrosion is more serious. Therefore, high-temperature deep well completion fluids must be equipped with high-temperature corrosion inhibitors during use to control or slow down the corrosion of steel by completion fluids.

[0003] Traditional completion fluid corrosion inhibitors are divided into inorganic and organic types. Inorganic completion fluid corrosion inhibitors mainly include chromates, nitrites, silicates, molybdates, tungstates, etc. Most of these inorganic completion fluid corrosion inhibitors are anodic corrosion inhibitors, which can inhibit the dissolution of metals into water and the anodic process of corrosion reactions by reacting with metal ions in the anode area of ​​the metal surface to form an oxide or hydroxide protective film to cover the anode, thereby achieving the purpose of corrosion inhibition; however, if not properly controlled, it will aggravate the occurrence of corrosion.

[0004] Organic completion fluid corrosion inhibitors include heterocyclic compounds containing nitrogen oxides such as phosphonic acid (salts), phosphonocarboxylic acid, mercaptobenzothiazole, and benzotriazole. These organic completion fluid corrosion inhibitors mainly rely on forming an adsorption film on the metal surface to prevent the diffusion of water and dissolved oxygen to the metal surface, control the occurrence of corrosion, and play a corrosion inhibition role. Organic completion fluid corrosion inhibitors can slow down the reaction of the cathode and anode at the same time, reducing the corrosion rate of steel, but the adsorption film can easily fall off from the metal surface at high temperatures and cannot play a slow release role.

[0005] In order to solve the above problems existing in the existing completion fluid corrosion inhibitors, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a high-temperature corrosion inhibitor for high-density completion fluid. The corrosion inhibitor has strong high-temperature resistance and can effectively inhibit the corrosion of downhole steel by high-density completion fluid under high-temperature and high-pressure conditions, thereby reducing completion operation accidents and improving completion efficiency. The inhibitor can be used for the development of high-temperature and high-pressure oil and gas reservoirs.

[0007] In a first aspect, the present invention provides a corrosion inhibitor, which is composed of a sulfur-containing organic amine compound and nonyl imidazoline; the mass ratio of the sulfur-containing organic amine compound to the nonyl imidazoline is 1:(0.3-0.4); preferably 1:0.33.

[0008] The sulfur-containing organic amine compound is a product obtained by the reaction of sodium sulfite with a sulfur source and a nitrogen source;

[0009] The nonyl imidazoline is a product obtained by reacting nonanoic acid, tetraethylene pentamine and toluene.

[0010] In the present invention, the mass ratio of the sodium sulfite to the sulfur source and the nitrogen source is 1:(0.3-0.4):(1.8-2.0).

[0011] In one embodiment, the mass ratio of the sodium sulfite to the sulfur source and the nitrogen source is 1:0.33:1.87.

[0012] In the present invention, the sulfur source is selected from one or more of sulfur powder, sodium sulfide and ammonium sulfide.

[0013] The nitrogen source is selected from one or more of ammonia water, ammonium chloride and ammonium sulfate.

[0014] In the present invention, the mass ratio of the nonanoic acid to the tetraethylenepentamine and the toluene is 1:(0.85-0.95):(0.25-0.35).

[0015] In a second aspect, the present invention also provides a method for preparing the above-mentioned corrosion inhibitor, comprising the following steps:

[0016] S1. Add sodium sulfite into water and dissolve it; add a sulfur source, heat it, and stir it; cool it, add a nitrogen source, and stir it to obtain a sulfur-containing organic amine compound;

[0017] S2, mixing nonanoic acid, tetraethylenepentamine and toluene in proportion, heating under reflux twice, and cooling to obtain nonyl imidazoline;

[0018] S3. Mixing the obtained sulfur-containing organic amine compound with nonyl imidazoline to obtain a corrosion inhibitor.

[0019] In the above method, step S1 is performed according to the following operation: a sulfur source and water of equal mass are mixed, added in batches, the system is heated to boiling at a rate of 5°C to 7°C / min, and boiling is maintained at a stirring rate of 250 to 350 rpm for 10 to 15 minutes. After the system is cooled to room temperature, a nitrogen source is added and stirred for 3 to 4 hours to obtain a sulfur-containing organic amine compound.

[0020] In step S2, the conditions of the two heating refluxes are as follows:

[0021] Primary heating reflux: heat to 175-185°C at a rate of 5-6°C / min, reflux for 3-4h;

[0022] Secondary heating reflux: heat to 215-225°C at a rate of 5-6°C / min and reflux for 3-4h.

[0023] In a third aspect, the present invention further provides a deep well completion method, comprising the following steps: using the above-mentioned corrosion inhibitor in combination with a completion fluid.

[0024] The completion fluid contains soluble salts; the soluble salts are selected from one or more of potassium formate, sodium formate and calcium chloride.

[0025] In one embodiment of the present invention, the completion fluid is a 38% by mass calcium chloride aqueous solution with a density of 1.39 g / cm 3 .

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The corrosion inhibitor provided by the present invention can react with metal under high temperature conditions to generate insoluble substances and precipitate on the metal surface to form a precipitation film. The precipitation film has significant high temperature resistance, and its temperature resistance is as high as 180°C. At the same time, the precipitation film can isolate the metal surface of the oil pipe, casing or downhole tool from the completion fluid, and is not easy to fall off, difficult to dissolve, has a good slow release effect, and the corrosion rate is less than 0.076mm / a (an industry-recognized indicator), thereby better inhibiting the continued occurrence of corrosion, so as to ensure the engineering safety of high-temperature and high-pressure oil and gas well completion and improve the economic benefits of oil and gas field development. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0030] Unless otherwise specified, the reagents, materials, instruments, etc. used in the following examples can be obtained from commercial sources.

[0031] Example 1. Preparation of corrosion inhibitor

[0032] This embodiment provides a corrosion inhibitor, which is prepared according to the following operations:

[0033] (1) The preparation of the sulfur-containing organic amine compound is carried out according to the following operation:

[0034] Mix 100g of water with 15g of sodium sulfite in a round-bottom flask, stir at 40℃ and 300 rpm for 45min to fully dissolve. Mix 5g of sulfur powder with water of equal mass and slowly add it to the round-bottom flask in 3 portions, slowly heat to boiling, and boil for 10-15min while stirring. Cool to room temperature, add 28g of ammonia water to the solution while stirring, and continue stirring at room temperature for 3-4h to obtain a sulfur-containing organic amine compound.

[0035] (2) Preparation of nonyl imidazoline, according to the following operation:

[0036] Add nonanoic acid, tetraethylenepentamine and toluene in a mass ratio of 100:90:30 into a round-bottom flask, heat to 180°C at a rate of 5-6°C / min, reflux for 3h, then heat to 220°C at a rate of 5-6°C / min, reflux for 3.5h, and cool naturally to obtain nonyl imidazoline.

[0037] (3) The sulfur-containing organic amine compound obtained above was mixed with nonyl imidazoline in a mass ratio of 1:0.33 to obtain a corrosion inhibitor.

[0038] Test example, high temperature corrosion resistance test

[0039] Different amounts of the corrosion inhibitor obtained in Example 1 were added to the high-density completion fluid, and the anti-corrosion performance of the above corrosion inhibitor on steel was tested with reference to the static hanging weight loss method in the Chinese petroleum and natural gas industry standard SY5273-2000.

[0040] The high-density completion fluid is a 38% calcium chloride aqueous solution with a density of 1.39 g / cm 3 .

[0041] The experimental time was 7 days.

[0042] The instrument used is a high temperature and high pressure corrosion instrument.

[0043] At the same time, 4% of conventional corrosion inhibitor was added to the completion fluid as a control test.

[0044] Table 1 Corrosion of high temperature corrosion inhibitors for high density completion fluids to steel

[0045]

[0046] It can be seen from the test data in Table 1 that the high-density completion fluid anti-high temperature corrosion inhibitor prepared in the embodiment has a corrosion resistance to 3Cr-L80 steel corresponding to the oil pipe and casing commonly used in oil and gas wells that is less than the industry standard of 0.076 mm / a, indicating that the high-density completion fluid anti-high temperature corrosion inhibitor has low corrosion to the pipe at high temperatures underground.

[0047] Comparative Example 1

[0048] The difference from Example 1 is that nonyl imidazoline is replaced by hexyl imidazoline.

[0049] The preparation of the above-mentioned hexyl imidazoline is carried out according to the following operation: caproic acid, tetraethylene pentamine and toluene are added into a round-bottom flask in a mass ratio of 100:90:30, heated to 180°C at a rate of 5-6°C / min, refluxed for 3h, then heated to 220°C at a rate of 5-6°C / min, refluxed for 3.5h, and naturally cooled to obtain hexyl imidazoline.

[0050] Comparative Example 2

[0051] The difference from Example 1 is that the sulfur-containing organic amine compound is replaced by cyclohexylamine.

[0052] According to the above test method, the compositions obtained in Comparative Example 1 and Comparative Example 2 were tested. The results are as follows.

[0053] Table 2 Screening experiment of corrosion rate under different combination conditions

[0054]

[0055] It can be seen from the test data in Table 2 that the corrosion rate of the high-temperature corrosion inhibitor for high-density completion fluid prepared in Example 1 on steel is significantly lower than the corrosion rate of the compositions prepared in Comparative Examples 1 and 2.

[0056] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A corrosion inhibitor, comprising a sulfur-containing organic amine compound and nonyl imidazoline in a mass ratio of 1: (0.3-0.4); The sulfur-containing organic amine compound is a product obtained by the reaction of sodium sulfite with a sulfur source and a nitrogen source; The nonyl imidazoline is a product obtained by reacting nonanoic acid, tetraethylene pentamine and toluene.

2. The corrosion inhibitor according to claim 1, characterized in that The mass ratio of the sodium sulfite to the sulfur source and the nitrogen source is 1:(0.3-0.4):(1.8-2.0).

3. The corrosion inhibitor according to claim 1 or 2, characterized in that The sulfur source is selected from one or more of sulfur powder, sodium sulfide and ammonium sulfide.

4. The corrosion inhibitor according to claim 1 or 2, characterized in that The nitrogen source is selected from one or more of ammonia water, ammonium chloride and ammonium sulfate.

5. The corrosion inhibitor according to any one of claims 1 to 4, characterized in that The mass ratio of the nonanoic acid to the tetraethylenepentamine and the toluene is 1:(0.85-0.95):(0.25-0.35).

6. The method for preparing the corrosion inhibitor according to any one of claims 1 to 5, comprising the following steps: S1. Add sodium sulfite into water and dissolve it; add a sulfur source, heat it, and stir it; cool it, add a nitrogen source, and stir it to obtain a sulfur-containing organic amine compound; S2, mixing nonanoic acid, tetraethylenepentamine and toluene in proportion, heating under reflux twice, and cooling to obtain nonyl imidazoline; S3. Mixing the obtained sulfur-containing organic amine compound with nonyl imidazoline to obtain a corrosion inhibitor.

7. The preparation method according to claim 6, characterized in that: Step S1 is performed as follows: a sulfur source and water of equal mass are mixed, added in batches, the system is heated to boiling at a rate of 5°C to 7°C / min, and the boiling is maintained at a stirring rate of 250 to 350 rpm for 10 to 15 min. After the system is cooled to room temperature, a nitrogen source is added, and the mixture is stirred for 3 to 4 hours to obtain a sulfur-containing organic amine compound.

8. The preparation method according to claim 6, characterized in that: In step S2, the conditions of the two heating refluxes are as follows: Primary heating reflux: heat to 175-185°C at a rate of 5-6°C / min, reflux for 3-4h; Secondary heating reflux: heat to 215-225°C at a rate of 5-6°C / min and reflux for 3-4h.

9. A deep well completion method, comprising the following steps: using the corrosion inhibitor according to any one of claims 1 to 5 in combination with a completion fluid.

10. The method according to claim 9, characterized in that The completion fluid contains soluble salts; The soluble salt is selected from one or more of potassium formate, sodium formate and calcium chloride.

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