RU2591923C1 - Inhibitor of sulphide corrosion and hydrogenation - Google Patents

Abstract

FIELD: metallurgy; technological processes.

SUBSTANCE: present invention relates to the protection of metals from sulphide corrosion and hydrogenation in the oil and gas industry and can be used to protect steel equipment and pipes in media with high hydrogen sulphide content. Inhibitor contains a nitrogen-containing active base that is a mixture of tertiary amine with a complex of monoalkyl phosphate and dialkyl phosphate, a demulsifying agent that is a mixture of polyethylene glycols and polypropylene glycol, an antifoaming agent based on organomodified silicones and organic components, as well as an isobutanol solvent.

EFFECT: such combination of components in certain proportions provides improved protective effect of a corrosion inhibitor against corrosion and hydrogenation in hydrogen sulphide-containing media at high temperatures, improved operational properties - low foaming properties in aqueous solutions of ethanolamines and fast disintegration of hydrocarbon-mineralised water emulsion.

1 cl, 7 tbl

Description

The invention relates to the field of protection of metals from hydrogen sulfide corrosion and hydrogenation in the oil and gas industry.

Known inhibitors of hydrogen sulfide corrosion and hydrogenation based on nitrogen-containing organic compounds - aliphatic amines, amido amines, imidazolines, etc. (Corrosion inhibitors: In 2 volumes. Volume 2. Diagnostics and protection against corrosion under stress of oil and gas equipment / N. A. Gafarov, V.M. Kushnarenko, D.E. Bugai et al .; Edited by D.E. Rakhmankulov. - M.: Chemistry, 2002 - 367 p.). The disadvantage of most of these inhibitors is a decrease in the protective effect with increasing temperature of the aggressive medium (Inhibition of hydrogen sulfide and carbon dioxide corrosion of metals. Universal inhibitors. Monograph. / V.I. Vigdorovich, L.E. Tsygankova - M .: Publishing House KARTEK, 2011. - 244 p. .). When producing gas in wells, temperatures can reach 110 ° C. The Dodigen 4482-1 corrosion inhibitor used at the Astrakhan gas condensate field (GKM) does not provide the necessary protection under these conditions (A.F. Svetlichkin, A.G. Filippov, I.G. Polyakov, etc. The state of anticorrosive protection in the "well- loop ". Exploration and development of oil and gas condensate fields. Scientific works of AstrakhanNIPIgaz / Compiled by the authors / - Astrakhan: CPI" Fakel "Astrakhangazprom LLC, 2005. - pp. 169-174).

The criterion for the use of inhibitors for the production of hydrogen sulfide-containing natural gases is the effectiveness of protection against general corrosion of at least 85%, from embrittlement of at least 70%. Corrosion inhibitors for conditions similar to the conditions of the Astrakhan gas condensate field must have a set of technological properties that enable their use. Inhibitors should have low foaming properties with respect to aqueous solutions of ethanolamines and not contribute to the formation of stable emulsions in the hydrocarbon condensate / formation water system. The increase in the foam of ethanolamine solutions should not be higher than 25 mm, the separation time of the emulsion hydrocarbon condensate / produced water should not exceed 5 minutes.

Inhibitors of hydrogen sulfide corrosion and hydrogenation are known based on nitrogen-containing compounds, including compounds obtained by the interaction of amines and carboxylic acids (Patent RU 2135483, IPC C23F 11/14, 2008), inhibitors containing tertiary amines (Patent RU 2064021 IPC C23F 11/14, 1996). At elevated temperatures (above 60 ° C), the effectiveness of these inhibitors decreases. In addition, the inhibitors of these patents contain compounds that cause foaming of aqueous solutions of ethanolamines.

Closest to the proposed invention in technical essence is the composition of the inhibitor for the protection of equipment and pipelines operated in aggressive environments under conditions of exposure to hydrogenation, carbon dioxide and hydrogen sulfide corrosion, containing the reaction product of carboxylic acids, polyethylene polyamine, demulsifier and solvent (RF Patent No. 2421549, IPC C23F 11/04, 2009). The disadvantage of this corrosion inhibitor is its low efficiency at elevated temperatures, which does not allow it to be used to protect downhole equipment (see Table 1. The effect of temperature on the protective effect of a corrosion inhibitor (prototype)).

The problem to which the invention is directed, is the creation of a corrosion and hydrogen retardant inhibitor with improved protective characteristics at elevated temperatures, with high technological properties.

The technical result to which this invention is directed is to increase the effectiveness of the protective effect of a corrosion inhibitor against general corrosion (at least 85%) and hydrogenation (at least 70%) in hydrogen sulfide-containing environments at elevated temperatures (up to 100 ° C), improving operational properties namely, ensuring low foaming properties in aqueous solutions of ethanolamines (increase in foam is not more than 25 mm), rapid decay of the emulsion hydrocarbon (oil, gas condensate) - mineralized water (time of separation pulse no more than 5 minutes).

This technical result is achieved due to the fact that the inhibitor of hydrogen sulfide corrosion and hydrogenation, containing a nitrogen-containing active base, demulsifier and solvent, additionally contains an antifoam based on organically modified silicones and organic components, while it contains a mixture of tertiary amine having the formula as a nitrogen-containing active base :

where R = octyl, dodecyl, hexadecyl,

with a mixture of monoalkyl phosphate and dialkyl phosphate having the formula:

where R = octyl, dodecyl, hexadecyl,

as a demulsifier - a mixture of polyethylene glycols and polypropylene glycols, and as a solvent - isobutanol, in the following ratio of components, wt.%:

nitrogen-containing active base: tertiary amine 20 ÷ 40 a mixture of monoalkyl phosphate and dialkyl phosphate 0.5 ÷ 20 antifoam 0.2-0.4 demulsifier 0.4-0.6 solvent up to 100

The essence of the invention is illustrated by examples of the protective effect of the claimed composition of the corrosion inhibitor (see Tables 2-4) and technological characteristics (see Tables 5-7).

As components of a corrosion inhibitor used industrial products:

- tertiary amine according to TU 2439-039-00203795-2010,

- alkyl phosphate according to TU 0257-008-35475596-2011,

- antifoam according to TU 2257-040-40245042-2002,

- demulsifier according to TU 2458-05765670-2008,

- alcohol solvent according to GOST 9536.

An inhibitor was prepared by simply mixing the components in a predetermined proportion.

The protective effectiveness of corrosion inhibitors was evaluated by the gravimetric method in autoclaves according to GOST 9.506-87 (ST SEV 5733-86) “Inhibitors of metal corrosion in water-oil environments. Methods for determining the protective ability "; the partial pressure of hydrogen sulfide is up to 2.0 MPa, carbon dioxide is 1.2 MPa, NACE solution (Water + 5% NaCl + 250 mg / dm ³ CH ₃ COOH), test temperature - 80 ° C.

Performance characteristics were evaluated using the following procedure.

Foam characteristics were evaluated in a 25% aqueous diethanolamine solution, the decay time of the hydrocarbon condensate / formation water emulsion (medium of the Astrakhan gas condensate field) was evaluated in accordance with the Methodological Instructions for Testing Corrosion Inhibitors for the Gas Industry. RAO Gazprom, VNIIGAZ, (second edition), M., 1996. The degree of protection against embrittlement of the metal was evaluated according to GOST 1579-93 (ISO 7801-84) “Wire. Kink test method. "

Tables 2-4 show the results of evaluating the protective effect against general corrosion and hydrogenation at different ratios of amine / alkyl phosphate and different ratios of defoamer, demulsifier and solvent. Table 2 presents the compositions of the proposed corrosion inhibitor with a defoamer content of 0.2 wt.%, Demulsifier 0.4 wt.%. Table 3 presents the compositions of the proposed corrosion inhibitor with a defoamer content of 0.3 wt.%, Demulsifier 0.6 wt.%. Table 4 presents the compositions of the proposed corrosion inhibitor with a defoamer content of 0.4 wt.%, Demulsifier 0.5 wt.%.

Tables 5-7 show the results of the evaluation of technological parameters at different ratios of amine / alkylphosphate and different ratios of defoamer, demulsifier and solvent.

From the above data it is seen that a change in the composition from the declared one leads to a violation of the set parameters both in terms of protective effect and in solidification temperature, foam height, and the time for the destruction of the hydrocarbon / water emulsion.

When the content of the nitrogen-containing active base in the proposed composition of the corrosion inhibitor is lower than the declared value, protective efficiency against general corrosion above 85% and from embrittlement above 70% for steel equipment and pipelines in environments with a high content of hydrogen sulfide is not provided.

According to the conditions of application of the proposed corrosion inhibitor, its pour point should be no higher than minus 35 ° C.

When the content of the nitrogen-containing active base in the proposed composition of the corrosion inhibitor is higher than the stated value, the pour point becomes higher minus 35 ° C.

Thus, the use of this invention provides an increase in the effectiveness of the protective effect of a corrosion inhibitor against general corrosion and hydrogenation in hydrogen sulfide-containing environments at elevated temperatures, as well as improved operational properties.

Claims (1)

A hydrogen sulfide corrosion and hydrogenation inhibitor containing a nitrogen-containing active base, a demulsifier and a solvent, characterized in that it further comprises an antifoam based on organically modified silicones and organic components, while it contains a mixture of a tertiary amine having the formula as a nitrogen-containing active base:

where R is octyl, dodecyl, hexadecyl,
with a mixture of monoalkyl phosphate and dialkyl phosphate having the formula:

where R is octyl, dodecyl, hexadecyl,
as a demulsifier - a mixture of polyethylene glycols and polypropylene glycols, and as a solvent - isobutanol, in the following ratio of components, wt.%:
nitrogen-containing active base: tertiary amine 20 ÷ 40 a mixture of monoalkyl phosphate and dialkyl phosphate 0.5 ÷ 20 antifoam 0.2-0.4 demulsifier 0.4-0.6 solvent up to 100