RU2627836C1 - Method of protecting steel from corrosion in mineralised water-oil media containing hydrogen sulphide - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method comprises adding 2-methyl-2-ethyl-5,7-di-(1-methylbut-2-EN-1-yl)indolin to the mineralised water-oil medium containing hydrogen sulphide at the concentration of 25-200 mg/l.

EFFECT: increasing the degree of protection from corrosion.

1 tbl, 3 ex

Description

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

Known methods of protecting steel from corrosion in acidic environments using inhibitors based on aromatic and heterocyclic compounds, such as catapines, which are adkylbenzylpyridinium chlorides, differing in the number of carbon atoms in the alkyl chain. The following brands of catapines are known: A, K, B-300, BPV, EPV (TU 6-01-530-70. Introduction. 06/01/1971, 13 pp.); the condensation product of benzylamine with urotropine (TU 6-02-1192-79. Corrosion inhibitor BA-6. Introduced 01.01.80, 13 C.); a mixture of alkylbenzylpyridine and a cyclic amine (TU 6-46893387-34-90. Corrosion inhibitor KI-1. Introduced 01.07.90. 12 sec.); a mixture of derivatives of toluene diisocyanates (TU 6-03-31-81. Corrosion inhibitor TDA. Int. 01.02.82, 13 p.); Quaternary pyridinium salt (TU 6-01-11-15-72. Corrosion inhibitor KPI-3. Introduced 01.02.73, 14 pp.).

However, these inhibitors do not have a high efficiency of steel protection 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. Introduction. 01.01.93, 11 pp.). The disadvantage of this inhibitor is its low efficiency in mineralized water-oil media containing hydrogen sulfide.

The problem to which the claimed technical solution is directed is to increase the efficiency of steel protection in mineralized water-oil media containing hydrogen sulfide.

The claimed technical solution proposes a method for protecting steel from corrosion in mineralized water-oil media containing hydrogen sulfide, including adding 2-methyl-2-ethyl-5,7-di- (1-methylbut) to a mineralized water-oil medium containing hydrogen sulfide -2-en-1-yl) indoline at a concentration of 25-200 mg / L.

Tests of the protective effect of 2-methyl-2-ethyl-5,7-di- (1-methylbut-2-en-1-yl) indoline as an inhibitor of steel corrosion in mineralized water-oil media containing hydrogen sulfide were carried out in laboratory conditions gravimetric method in accordance with GOST 9.506-87 "Inhibitors of metal corrosion in water-oil environments", Standards Publishing House, 1988.

As working media, we used a model of mineralized water (MMW) of the composition, g / l: NaCl - 163.00; CaCl ₂ ⋅ 6H ₂ O - 34.00; CaSO ₄ ⋅ 2H ₂ O - 0.14; MgCl ₂ ⋅ 6H ₂ O - 17.00 and oil prepared according to group 1 GOST 9965-76, in the ratio of 70:30.

The hydrogen sulfide content was 1300 mg / L. As witness samples used plates of steel grade 3 (GOST 380-90).

Fat-free and dried to constant weight samples of steel grade 3 were placed in the working environment for 6 hours at 20 ° C with the addition of the proposed inhibitor and without it. After the aging time, the samples were thoroughly washed in a stream of water, immersed for 5-10 minutes in an alkali solution, washed again 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 test time, h;

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 2-methyl-2-ethyl-5,7-di- (1-methylbut-2-en-1-yl) indoline

2-methyl-2-ethyl-5,7-di- (1-methylbut-2-en-1-yl) indoline was prepared by reacting indoline with piperylene in the presence of AlCl ₃ at a temperature of 130 ° C in an autoclave. 1 g of indoline, 10 ml of benzene, 0.3 g of AlCl ₃ and 2.1 g of piperylene were placed in a 17 ml autoclave. The reaction mixture was heated at 130 ° C for 5 hours. The reaction mixture was chromatographed on silica gel using petroleum ether-ethyl acetate (5: 1) as eluent. 1.9 g of product are obtained with a yield of 61%.

¹ H NMR Spectrum (CDCl ₃ , δ, ppm, Z [E]): 0.90 [0.93] (3H, t, ³ J = 7.4, H-2ʺ '); 1.19 [1.25] (3H, s, H-1ʺʺ); 1.30 [1.34] (3H, d, ³ J = 7.0, H-4 ', H-4ʺ); 1.61 [1.55] (2H, q, ³ J = 7.0, H-1ʺ '); 1.67 [1.69] (3H, d, ³ J = 6.0, H-5 ', H-5ʺ); 2.74 [2.73] (1H, d, ³ J = 15.5, H-3 ^b ); 2.86 [2.87] (1H, d, ³ J = 15.5, H-3 ^a ); 3.29 [3.32] (2H, m, H-1 ', H-1ʺ); 5.44 [5.44] (1H, m, H-3 '); 5.47 [5.47] (1H, m, H-3ʺ); 5.53 [5.53] (1H, m, H-2 '); 5.62 [5.62] (1H, m, H-2ʺ); 6.72 [5.72] (1H, s, H-6); 6.79 [6.79] (1H, s, H-6).

¹³ C NMR spectrum (CDCl ₃ , δ, ppm, Z [E]): 8.76 [9.08] (C-2ʺ '); 17.62 [17.96] (C-5 ', C-5ʺ); 18.81 [18.85] (C-4 '); 21.88 [21.94] (C-4ʺ); 26.49 [26.82] (C-1ʺʺ); 34.41 [34.79] (C-1ʺ '); 38.19 [38.36] (C-1ʺʺ); 42.03 [42.09] (C-3); 42.25 [42.21] (C-1 '); 63.81 [63.95] (C-2); 121.25 [121.27] (C-4); 122.54 [122.54] (C-3 '); 123.35 [123.33] (C-6); 123.60 [123.69] (C-3ʺ); 125.51 [125.61] (C-5); 128.39 [128.53] (C-7); 135.25 [135.26] (C-2 '); 136.52 [136.53] (C-4a); 137.35 [137.39] (C-2ʺ); 146.65 [146.66] (C-7a).

Example 2

Testing the effectiveness of the protective effect of 2-methyl-2-ethyl-5,7-di- (1-methylbut-2-en-1-yl) indoline as an inhibitor of steel was carried out according to the method described above.

In the water-oil mixture MMW: oil with a hydrogen sulfide content of CH ₂ s = 1300 mg / l, the corrosion rate without inhibitor is 0.80 g / m ² ⋅ h, and in the presence of 200 mg / l 2-methyl-2-ethyl- 5,7-di- (1-methylbut-2-en-1-yl) indoline (hereinafter reagent) - 0.036 g / m ² ⋅h. The degree of corrosion protection under these conditions is 95.5%.

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 in the water-oil mixture MMB: oil containing hydrogen sulfide CH ₂ s = 1300 mg / l, is 0.80 g / m ² ⋅ h without reagent and 0.46 g / m ² ⋅ h in the presence of 200 mg / l of the prototype. The degree of protection under these conditions is 42.5%.

The table shows the remaining examples of testing the reagent as an inhibitor of corrosion of steel.

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 with an inhibitor concentration of 25 to 200 mg / L. With an increase in inhibitor concentration above 200 mg / L, the degree of protection does not change significantly, and with a decrease in its concentration below 25 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 0.46 g / m ² ⋅ h, and the degree of protection is 42.5%.

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

1. A high degree of corrosion protection of 2-methyl-2-ethyl-5,7-di- (1-methylbut-2-en-1-yl) indoline (86.25-95.5%) compared with the prototype ( 42.5%).

2. The decrease in the corrosion rate of steel in the presence of 2-methyl-2-ethyl-5,7-di- (1-methylbut-2-en-1-yl) indoline by 7.3-22.2 times, and in the presence of the prototype - 1.7 times.

3. Effective dosages of the proposed inhibitor are 25-200 mg / l (degree of protection 86.25-95.5%), and in the prototype, even at dosages of 200 mg / l, the degree of protection does not exceed 42.5%.

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.

Claims (1)

A method of protecting steel equipment from corrosion in mineralized water-oil media containing hydrogen sulfide, including adding 2-methyl-2-ethyl-5,7-di- (1-methylbut-2-ene) to a mineralized water-oil medium containing hydrogen sulfide -1-yl) indoline at a concentration of 25-200 mg / L.