RU2353708C1 - Protection method of steel against corrosion in mineralised trolly medium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to area of metal protection against corrosion in mineralised of trolly medium, including hydrogen sulphide, inhibitors and can be used with protection against corrosion pipelines and equipment in petrolic branch. Method includes addition into mineralised trolly medium corrosion inhibitor, at that in the capacity of corrosion inhibitor it is used N-acetyl-2-(2.3-dihydroxycilopentenyl) aniline with concentration 50-200 mg/l. Level of protection of steel is 87.8-96.0%.

EFFECT: increasing of steel protection rating.

1 tbl, 3 ex

Description

The invention relates to a method for protecting metals from corrosion in water-oil media by inhibitors and can be used in corrosion protection of equipment in the oil industry in contact with mineralized water-oil media containing hydrogen sulfide.

Many derivatives of aromatic and heterocyclic compounds are known as corrosion inhibitors in acidic and neutral mineralized environments: the condensation product of benzylamine with urotropine (TU 6-02-1192-79. Corrosion inhibitor BA-6. Introduction. 01.01.80.13 p.); a mixture of alkylbenzylpyridine and a cyclic amine (TU 6-46893387-34-90. Corrosion inhibitor KI-1. Introduced 01.07.90.12 p.); a mixture of derivatives of toluene diisocyanates (TU 6-03-31-81. Corrosion inhibitor TDA. Introduced 01.02.82.13 p.); derivatives of alkyl pyridinium chlorides (TU 6-01-530-70. Corrosion inhibitor Katapin B-300. Introduction. 01.01.71.13 p.); Quaternary pyridinium salt (TU 6-01-11-15-72. Corrosion inhibitor KPI-3. Introduced 01.02.73.14 p.).

However, these inhibitors do not have a high protection efficiency in mineralized water-oil media containing hydrogen sulfide.

The closest analogue in structure and effectiveness is the PB-5 corrosion inhibitor, which is a condensation product of aniline and urotropin (TU 6-01-28-92. The PB-5 corrosion inhibitor. Introduced 01.01.93.11 p.) The disadvantage of this inhibitor is its low Efficiency in mineralized water-oil media containing hydrogen sulfide.

The claimed technical solution is aimed at improving the efficiency of corrosion protection of steel in mineralized water-oil environments containing hydrogen sulfide.

In the claimed technical solution, a method is proposed for protecting steel from corrosion in mineralized water-oil media, including the addition of an inhibitor, N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline, of the formula (1) to the mineralized water-oil medium

N-Acetyl-2- (2,3-dihydroxycyclopentenyl) aniline is obtained by oxidation of N-acetyl-2- (cyclopent-2-enyl) aniline with potassium permanganate (Dyachenko DI Ozonolysis of orthoalkenyl derivatives of anilines and phenols. - Dis ... cand. Chemical Science - Ufa: IOCH USCH RAS, 2006). Tests of the protective effect of N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline as a steel corrosion inhibitor in mineralized water-oil media were carried out under laboratory conditions by the gravimetric method in accordance with OST 39-099-79 “Corrosion inhibitors. A method for evaluating the effectiveness of the protective effect of corrosion inhibitors in oilfield wastewater. " A mixture of the model of mineralized water (MMW) and oil in a ratio of 80:20 was used as working media. As the MMB, a water-salt mixture of the composition was used, g / l: NaCl — 111.5; CaCl ₂ · 6H ₂ O — 10.8; MgCl ₂ · 2H ₂ O - 17.0; CaSO ₄ · 2H ₂ O - 0.3. The content of H ₂ S was 900-1500 mg / L. Samples of steel grade 3 (GOST 380-90) were used as witness samples.

Fat-free and dried to constant weight samples of steel 3 were placed in a working environment for 6 hours at 20 ° C with the addition of the inventive reagent and without it. After the aging time, the samples were immersed for 5-10 minutes in an alkali solution, washed with running water and dried to constant weight. Next, the samples were weighed to the nearest 0.0002 g.

The corrosion rate (p), the degree of corrosion protection of steel (Z) was determined in accordance with formulas (1) and (2)

where m ₁ -m ₂ - change in mass, g;

S is the sample area, m ² ;

t is the test time, h

where p ₁ is the corrosion rate in a medium without an inhibitor, g / m ² · h;

p ₂ - corrosion rate in an inhibited medium, g / m ² · h

The essence of the claimed technical solution is confirmed by examples of specific performance.

Example 1

Synthesis of N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline.

To 20 mmol of N-acetyl-2- (2-cyclopentenyl) aniline in 70 ml of acetone and 10 ml of water at room temperature with vigorous stirring for 30 min, 20 mmol of finely ground KMnO _{4 was} added in small portions, which almost immediately turned into insoluble precipitate. The precipitate was filtered off, washed with acetone and the filtrate was evaporated in vacuo. 16.5 g (87%) of N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline were obtained.

Found,%: C 77.40; H, 7.22; N, 6.79; C ₁₃ H ₁₇ NO ₂ .

Calculated: C 77.61; H 7.46; N, 6.97.

H NMR spectrum, (CDCl ₃ , g, ppm): 1.70 (m, 2H, CH ₂ ); 2.12 (s, 3H, CH ₃ );

2.45 (m, 2H, CH ₂ ); 2.83 (m, 2H, 2 (OH)); 3.68 (m, 1H, CH); 4.02 (s, 1H, NH); 4.12 (m, 1H, CH); 4.97 (m, 1H, CH); 7.07-7.38 (m, 4H, Ar).

Example 2

Testing the effectiveness of the protective action of N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline as an inhibitor of steel corrosion was carried out according to the method described above.

In a mineralized water-oil medium containing 1500 mg / l H ₂ S, the corrosion rate without inhibitor is 0.90 g / m ² · h, and in the presence of 200 mg / l N-acetyl- (2,3-dihydrocyclopentenyl) aniline (hereinafter reagent) - 0.036 g / m ² · h.

The degree of corrosion protection under these conditions is 96.0%.

Example 3

Testing the effectiveness of the corrosion protection of the prototype (PB-5 inhibitor) was carried out analogously to example 2. The corrosion rate of steel in a saline water-oil medium with a content of H ₂ S of 1500 mg / l is 0.90 g / m ² · h without reagent and 0.504 g / m ² · h in the presence of 200 mg / l of the prototype. The degree of protection under these conditions is 56.0%.

The table shows the rest of the test examples of N-acetyl-2- (2,3-dihydroxypentenyl) aniline as an inhibitor of steel corrosion.

The test results shown in the table indicate the high efficiency of the proposed corrosion inhibitor of steel in mineralized water-oil environments containing hydrogen sulfide. The highest efficiency is achieved when the inhibitor concentration is from 50 to 200 mg / l. With an increase in the inhibitor concentration above 200 mg / L, the degree of protection does not change significantly, and with a decrease in its concentration below 50 mg / L, a sharp decrease in the degree of protection is observed. In the case of the prototype at a concentration of 200 mg / l, the corrosion rate is 0.504-0.324 g / m ² · h, and the degree of protection is 44.1-56.0%.

The advantages of the proposed corrosion inhibitor of steel in comparison with the prototype are as follows.

1. A high degree of corrosion protection N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline (87.8-96.0%) compared with the prototype (44.1-56.0%).

2. The decrease in the corrosion rate of steel in the presence of N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline by 6.2–25 times, and in the presence of the prototype - 1.78-2.57 times.

3. Effective dosages of the proposed inhibitor are 50-200 mg / l (degree of protection 87.8-96.0%), and in the prototype, even at dosages of 200 mg / l, the degree of protection does not exceed 56.0%. The results obtained allow us to conclude that the proposed method for protecting steel from corrosion in mineralized water-oil media containing hydrogen sulfide, which can be used in the oil industry, is highly effective.

Table 1
Test results of N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline as an inhibitor of steel corrosion in mineralized water-oil media Example No. The content of hydrogen sulfide, mg / l Inhibitor concentration, mg / l The corrosion rate, g / m ² · h Degree of protection, % Iím: oil = 80: 20
1500 - 0.90 - 2 200 0,036 96.0 3 (prototype) 200 0.504 56.0 four one hundred 0,054 94.0 5 fifty 0.108 88.7 1200 0.76 6 200 0,041 94.6 7 (prototype) 200 0.35 48.0 8 one hundred 0.06 92.0 9 fifty 0,093 87.8 900 0.58 10 200 0.04 93.1 11 (prototype) 200 0.324 44.1 12 one hundred 0.058 90.0 13 fifty 0,071 87.8

Claims (1)

A method of protecting steel from corrosion in mineralized water-oil media, including adding a corrosion inhibitor to the mineralized water-oil medium, characterized in that N-acetyl-2- (2,3-dihydroxycyclopentenyl) aniline with a concentration of 50- is used as a corrosion inhibitor 200 mg / l.