INVESTIGATION OF HIGH-ALLOY CHROME-NICKEL STEELS CORROSION RESISTANCE

Abstract

Background Oil and gas equipment is subjected to intense internal corrosion throughout the entire process of oil and gas production and treatment. Corrosive aggressiveness of the environment is provided by dissolved gases present in the formation and waste waters: oxygen, hydrogen sulphide, carbon dioxide, as well as the vital activity of bacteria and high mineralization. The most dangerous consequence of these factors is the development of local corrosion on the metal. Highly significant equipment in the oil and gas fields are the tubing and casing pipes. One of the ways to improve their durability is to use corrosion-resistant steels that are highly resistant to acidic and alkaline environments, as well as aggressive salt solutions. High-alloy chromium-nickel steels of 08Kh18N10T and 10X17N13M2T grades are often used for these purposes. Aims and Objectives Study of 08Х18Н10Т and 10Х17Н13М2Т steels to pitting corrodibility. Investigation of the of inhibitor protection influence on the change in corrosion rate of underground equipment and pipelines of producing wells at the fields of Samotlorneftegaz JSC using the simples of 08Х18Н10Т and 10Х17Н13М2Т steels. Metods Gravimetric tests of the steels under investigation were carried out in accordance with State Standard 9.502-82 «Unified system for protection against corrosion and aging. Metal corrosion inhibitors for water systems. Methods of corrosion testing». Tests on pitting corrodibility were carried out in accordance with State Standard 9.912-89 «Steels and alloys are corrosion-resistant. Methods of accelerated tests for resistance to pitting corrosion». Polarization studies were performed on the Field Machine potentiostat in a three-electrode clamp electrochemical cell. Corrosive media for polarization studies was a model fluid simulating the composition of the reservoir water of the Samotlor field. Results As a result of gravimetric tests, it is established that in highly aggressive chlorine-containing media steels 08Х18Н10Т and 10Х17Н13М2Т are subjected to local pitting corrosion, and the corrosion resistance of steel 10Х17Н13М2Т is higher than that of 08Х18Н10Т steel. Based on the results of polarization studies, it has been established that the application of the corrosion inhibitor SONKOR-9011 at a concentration of 30 ppm provides a shift in the corrosion potential of the steels to be investigated in the positive range, with a protective effect of 66 %.