RU2061098C1 - Corrosion inhibitor - Google Patents

Abstract

FIELD: corrosion protection. SUBSTANCE: corrosion inhibitor belongs to compounds for protection against corrosion and absorption of hydrogen, enables foam formation to be reduced and protection degree to be enhanced. Inhibitor contains substance chosen from group including aminoalcohols, polyamines and imidazolines and product of treatment of oleophines C₅-C₄₀ with elementary sulphur in presence of activator of amine class with mass proportion of specified ingredients 1:4-4:1. Inhibitor is used in the form of stable condensate. Corrosion inhibitor can be used for protection of internal surfaces of pipes of wells in oil and gas industries. EFFECT: increased protective properties. 3 cl, 7 dwg

Description

 The invention relates to compositions of compositions used as corrosion inhibitors of ferrous metals in aggressive environments containing elevated concentrations of hydrogen sulfide and carbon dioxide. The inhibitor in accordance with the invention can be used to protect the pipe space of the wells, the inner surface of the pipes during transport, etc. in the oil and gas industry.

The inhibitory properties of nitrogen-containing organic compounds-alkyl amines C ₄ -C ₁₀ , polyamines and imidazolines are known (A. Altsybeeva, S. Levin. Metal corrosion inhibitors. / Ed. By L.I. Antropov, L. Chemistry, 1968, p. 7- 12, 130 and 95), on the basis of which INCORAX, SECANGAS and SEPACORR inhibitors are produced by industry, respectively.

 Disadvantages high foaming and tendency to salt formation.

Known compositions with antiwear and antioxidant properties, which are products of elemental sulfur treatment of C ₅ -C ₁₅ olefins in the presence of C ₁₅ -C ₂₅ aliphatic amines (TOC) or C ₂₈ -C ₄₀ polyolefins in the presence of diphenylamine (OTP) (a.c. USSR N 1162805, class C 07 D 399/08, 1985 and application N 46712269/04 of 04/03/89). The compositions are used as extreme pressure additives in gear oils, their anticorrosive properties are low.

Closest to the proposed is a corrosion inhibitor comprising a nitrogen-containing compound cyclic amidine and colloidal sulfur [1]
This reduces the corrosion inhibitor in hydrogen sulfide environments of 4-5, but its use in factory conditions, gas treatment and processing units (e.g., AGCF) is complicated due to the propensity of resinification and degradation at high ⁽¹²⁰ ° C) temperatures, which contributes to foaming on amine desulfurization plants. In addition, the indicated inhibitor does not provide sufficient protection against hydrogenation.

To provide a high degree of protection against corrosion and hydrogenation and to prevent foaming, a corrosion inhibitor is proposed containing nitrogen and sulfur-containing components, which as a nitrogen-containing component contains a substance selected from the group consisting of C ₄ -C ₁₀ alkylamines, polyamines and imidazolines, and sulfur-containing component the product of the processing of olefins With ₅ -C ₄₀ elemental sulfur in the presence of an activator from the class of amines, with a mass ratio of nitrogen and sulfur-containing component 1: 4 4: 1.

As a sulfur-containing component, the inhibitor may contain the product of elemental sulfur treatment of C ₅ -C ₁₅ olefins in the presence of aliphatic amines (TOC additive) or C ₂₈ -C ₄₀ polyolefins in the presence of diphenylamine (OTP additive).

 An inhibitor is obtained by mixing its constituent ingredients. It is a dark brown liquid, soluble in mixtures of hydrocarbons of normal iso-naphthenic and aromatic structures and insoluble in water and lower alcohols. The proposed inhibitor is used in the form of a solution (≥5%) in a hydrocarbon solvent, for example gasoline, kerosene GOST 4753-68 or nefras GOST 443-76, stable condensate AGKM.

 An increase in the content of a sulfur-containing component above the claimed limit reduces the protective properties of the composition, a decrease increases the tendency to paraffin deposition.

 In laboratory tests of known and proposed inhibitors, samples of Art. 20 (corrosion protection) and 70С2ХА steel (hydrogenation).

Aggressive medium 3% aqueous NaCl solution containing 250 mg / l CH ₃ COOH and 2 g / l hydrogen sulfide.

The protective effect was evaluated by the gravimetric method (ρg / m ² h), anti hydrogenation by vacuum extraction (cm ³ / 100g metal).

 The tendency to foaming solutions was evaluated by the height of the foam at an air flow rate of 6 l / min.

 PRI me R 1. In laboratory conditions, the properties of the individual ingredients that make up the proposed corrosion inhibitor. The test substance was used as a 10% solution in gasoline. The specified solution was introduced into the aggressive environment in quantities of 0.1 and 0.5%. Test time 2 hours. The results are presented in table. 1.

 From the data presented in table. 1, it follows that alkylamine, polyamine and imidazoline have high anticorrosive properties. Adequate protection against hydrogenation is provided only by alkylamine and imidazoline. But all of these substances cause foaming and scaling. TOC and OTP do not cause foaming and scaling, while having low protective properties.

PRI me R 2. We studied the protective properties of the proposed corrosion inhibitor containing, as a nitrogen-containing ingredient, alkyl amines C ₄ -C ₁₀ , polyamines, imidazoline, as well as known corrosion inhibitors based on them INCORAX, SECANGAS and SEPACORR, respectively. The amounts of the latter in the compositions are given in terms of the content of the corresponding active component in them. As a sulfur-containing component, TOC and OTP were used. The mass ratio of the components in all cases is 1: 1, the solvent is gasoline. The concentration of inhibitor in gasoline is 10%. Into an aggressive medium, this solution was introduced in an amount of 0.1 and 0.5%. 2.

 Of the presented in table. 2 data it follows that the "pairwise" test results are almost the same, therefore, for the preparation of the inhibitor can be used as individual substances and inhibitors on the basis of.

PRI me R 3. Were prepared and tested model compositions of the proposed corrosion inhibitor with a different ratio of ingredients included in its composition. The numbers of the compositions and their compositions are presented in table. 3. From these compositions, a 10% solution in gasoline was prepared, an inhibitor film was applied to the sample surface from the solution by “dipping”, and after removing excess solution, the coated samples were placed in a corrosive medium. The tests were carried out in autoclave conditions simulating the operation of well equipment in bottomhole zones. The total system pressure of 8.0 MPa, the partial pressure of carbon dioxide and hydrogen sulfide, and 2.5 respectively 1.5 MPa, temperature ⁸⁰ ° C Test duration 48 hours. The test results are shown in Table. 4. It also shows the test results of the prototype inhibitor when the mass ratio of ingredients in it is 1: 1 (which corresponds to compositions N 4, 10 and 14 from table. 3).

 From the data presented in table. 4, it follows that the proposed corrosion inhibitor provides a higher degree of corrosion protection than the prototype, and significantly exceeds it in terms of protection against hydrogen pickup. In addition, it does not cause foaming and scaling.

 Comparison of the data table. 1 and 4 shows that the proposed inhibitor in its qualities also significantly exceeds the ingredients that make up its composition, exhibiting the phenomenon of synergism.

Example 4. The study of the protective properties of the proposed inhibitor versus time was carried out in an autoclave experiment simulating the conditions of a high sulfur deposit: an aqueous medium containing 3% NaCl, 2.50 mg / l CH ₃ COOH. The partial pressures of hydrogen sulfide and carbon dioxide are 1.5 and 2.5 MPa, respectively, and the total pressure of the system is 8.0 MPa. Studies were carried out on the composition of N 10 from the table. 3 and clean SECANGAZ. The results are presented in table. 5. The presence of pitting and ulcers is marked with a "*".

 From the data table. 5 it follows that the proposed corrosion inhibitor has high protective properties that maintain stability over time, and also prevents local corrosion.

 In addition, the proposed inhibitor was investigated for aftereffect of the protective film and a tendency to paraffin formation.

 Example 5. The study of the aftereffect of the protective properties of the film of the proposed inhibitor was carried out on a composition containing, as a nitrogen-containing component, INCORAX, a sulfur-containing OTP in the ratio 1: 1, 1: 3, 3: 1. The film was applied by dipping into a 10% solution of the inhibitor in gasoline, then the film-coated sample was washed off with an aggressive medium and placed in a corrosive environment. The results are presented in table. 6.

 From the table. 6 it follows that the sorbability of the proposed inhibitor and, as a consequence, its aftereffect is about 3 times higher than that of INCORAX included in its composition.

 PRI me R 6. The study of the effect of the proposed inhibitor on paraffin formation was carried out on the product pipeline Sovetabad gas field PO "Turkmengazprom". The amount of paraffin deposits was determined gravimetrically: pre-weighed plates of art. 10 were kept for 4 hours in the test composition, the excess product was allowed to drain at room temperature for 18 hours, and the plates with the product remaining on them were re-weighed. The specific gravity of the product on the surface of the plate was calculated. Protective efficiency was determined in the gas phase containing 1000 mg / l of hydrogen sulfide according to paragraph 4.3 of TU 38 401864-91. Used formulations N 4 and 10 of the proposed inhibitor from table. 4. The results are shown in table. 7.

From the presented data it follows that the introduction of the proposed inhibitor in the condensate reduces paraffin deposition by about 6 times, while increasing the protective properties of the condensate from 65 to ≈90%
Thus, the proposed corrosion inhibitor with a high degree of protection against general corrosion significantly surpasses known inhibitors (analogues and prototype) in such qualities as protection against hydrogen pickup, aftereffect, duration of the protective effect while suppressing foaming, salt and paraffin deposition.

Claims (3)

1. A corrosion inhibitor containing nitrogen and sulfur-containing components, characterized in that as a nitrogen-containing component it contains a substance selected from the group consisting of alkyl amines C ₄ - C _{1 0} , polyamines and imidazolines, and as a sulfur-containing component, the product of processing olefins C ₅ With _{4 0} elemental sulfur in the presence of an activator of the class of amines with a ratio of components 1: 4-4: 1 wt. 2. The corrosion inhibitor according to claim 1, characterized in that, as a sulfur-containing component, it contains a product of the processing of elementary sulfur C ₅ C _{1 5} olefins in the presence of aliphatic amines C _{1 5} C _{2 5} . 3. The corrosion inhibitor according to claim 1, characterized in that, as a sulfur-containing component, it contains a product of the processing of elementary sulfur olefins With _{2 8} With _{4 0} in the presence of diphenylamine.

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