«Oilfield engineering»

FEATURES OF THE MECHANISM THE LOCAL CORROSION IN HYDROGEN SULFIDE-CONTAINING ENVIRONMENTS

UDC: 622.276:620.193.462.21
DOI: 10.33285/0207-2351-2021-9(633)-46-53

Authors:

¹ LLC "RN-BashNIPIneft", Ufa, Russian Federation
² Federal state-financed organization of science Institute of Chemistry Far-East department of Russian Academy of Sciences, Vladivostok, Russian Federation
³ Nizhnevartovsk branch of Federal State Budget Educational Institution of Higher Education "Industrial University of Tyumen", Nizhnevartovsk, Tyumen region, Russian Federation
⁴ JSC "Orenburgneft" PJSC "NK "Rosneft", Moscow, Russian Federation

Keywords: corrosion, Hydrogen Sulfide-containing Media, localized corrosion, complicated mechanized well stock, downhole equipment, iron sulfide, mackinawite, Greigite, x-ray spectral analysis, Energy dispersive X-ray fluorescence analysis

Annotation:

Complications associated with the corrosive environment, according to JSC "Orenburgneft", PJSC "NK "Rosneft" for the period 01.01.2021, are among the prevailing at oil and gas production facilities and share the 1st place with the scaling factor - 26 % of the complicated mechanized well stock. Downhole equipment failures due to corrosion account for 20 % of the total number of fixed failures in 2020. By the type of exposure to a corrosive environment at the fields operated within the perimeter of Rosneft, JSC "Orenburgneft", hydrogen sulfide and mixed corrosion, caused by simultaneous action of CO2 and H2S, are predominant. The article presents the calculated data on the physicochemical characteristics of aqueous solutions of H2S. The existing approaches for description the mechanisms of hydrogen sulfide corrosion of oilfield equipment are described. The study results of deposits from the inner surface tubing after running in hydrogen sulfide-containing media, obtained using the X-ray diffractometric method, are presented. The deposit’s elemental and mineral composition has been established by X-ray spectral analysis. Next to sulfide (makinawite) and polysulfide (greigite) of iron, the samples were found to contain calcium and strontium carbonates, sodium chloride and quartz, which are products the accompanying scaling process and mechanical impurities. The difference between the obtained results and a number of theoretical concepts on the stability of the existence the polymorphic forms of iron sulfides, based on the laboratory studies, is shown, and is confirmed by the results of the operation of oilfield equipment. Despite the fact that makinavite is considered the most unstable form of iron sulfide, it can be present mainly in the form of this polymorphic form in the sediments of real oilfield systems. According to the research results, a qualitative and quantitative assessment of sulfide and polysulfide sulfur, carried out by the method of energy dispersive X-ray fluorescence analysis, is shown. The diffraction patterns of the obtained spectra are presented, the interpretation of which shows the possibility of classifying the ongoing corrosion processes by a mixed mechanism at a concentration ratio of corrosive gases CO2/H2S = 4, which is confirmed by the simultaneous presence of sulfides and carbonates in corrosion products.

Bibliography:

1. Соловьев Н.Н., Салина Л.С., Скоробогатов В.А. Основные закономерности размещения и формирования залежей сероводородсодержащего газа // Вести газовой науки. - 2016. - № 1(25). - С. 125-133.
2. Лурье Ю.Ю. Справочник по аналитической химии: 4-е изд. - М.: Химия, 1971. - 456 с.
3. Vaughan D.J., Craig J.R. Mineral chemistry of metal sulfides. First ed. - New York: Vail-Ballou, 1978. - P. 17-117.
4. Smith S.N., Joosten M.W. Corrosion of Carbon Steel by H2S in CO2 Containing Oilfield Environments // Corrosion. - 2006. - Paper No. 06115. - NACE Int.: Houston, TX, USA.
5. Saba N.E. Galvanic Localized Corrosion of Mild Steel under Iron Sulfide Corrosion Product Layers: A dissertation presented to the faculty of the Russ College of Engineering and Technology of Ohio University. - 2018.
6. Chemical characterization of corrosion films electrochemically grown on carbon steel in alkaline sour environment / E. Sosa, R. Cabrera-Sierra, M.T. Oropeza [et al.] // J. Electrochem. Soc. - 2003. - № 150. - B530-B535.
7. FeS Corrosion Products Formation and Hydrogen Uptake in a Sour Environment for Quenched and Tempered Steel / E. Wallaert, T. Depover, I. De Graeve, K. Verbeken // Metals. - 2018. - Vol. 8, № 62. - DOI: 10.3390/met8010062
8. Синютина С.Е., Вигдорович В.И. Современное состояние и проблемы сероводородной коррозии металлов в растворах электролитов // Вестник ТГУ. - 2002. - Т. 7, № 3. - С. 319-328.
9. Гоник А.А. Сероводородная коррозия и меры ее предупреждения. - М.: Недра, 1966. - 176 с.
10. Локальная СО2-коррозия нефтепромыслового оборудования: монография / В.Э. Ткачева, А.В. Бриков, Д.А. Лунин, А.Н. Маркин. - Уфа: РН-БашНИПИнефть, 2021. - 168 с.
11. Саакиян Л.С., Ефремов А.П. Защита нефтегазопромыслового оборудования от коррозии. - М.: Недра, 1982. - 206 с.
12. Wijord A.G., Rummery T.E., Doem E.F. Corrosion and deposition during the exposure of carbon steel to hydrogen sulphide-water solutions // Corrosion Science. - 1980. - V. 20. - № 5. - P. 651-671.
13. Баринов О.Г. Механизм локализации коррозии на железе в растворах, содержащих сероводород: автореф. дис. … канд. хим. наук. - М., 2002. - 129 с.
14. Коррозия внутрискважинного оборудования в сероводородсодержащих средах / В.Э. Ткачева, А.Н. Маркин, Д.В. Кшнякин [и др.] // Практика противокоррозионной защиты. - 2021. - Т. 26, № 2. - С. 7-26.