Development of methodological aspects of studies of corrosivity and inhibitor protection during production and transportation of CO₂-containing gas

• D.N. Zapevalov¹, R.K. Vagapov¹, K.V. Chumakov², A.D. Gaizullin¹, A.M. Laptev² and D.S. Fedotov¹

¹ Gazprom VNIIGAZ LLC, 15 Gazovikov St., bld. 1, Razvilka, Leninsky municip., Moscow region, 142717, Russian Federation
² Bauman Moscow State Technical University, 1st Institutskaya street, 1, Mytishchi, 141005, Russian Federation

Abstract: Nowadays the problem of combating internal corrosion is acute at gas facilities under the conditions of hydrocarbons production and transportation in the presence of aggressive CO₂. The article examines the main conditions for the carbon dioxide corrosion occurrence of in a gas pipeline. They differ significantly from the conditions of oil fields by the degree of filling of the pipe space with the liquid phase and the aggregate state of the main produced fluids. These differences affect corrosion manifestations. Thus, it requires a special consideration and approach to modelling corrosion tests specifically for gas pipeline conditions. The study of corrosion processes that occur during gas transportation in the presence of a liquid phase through the gas pipeline served as the basis for the development of two corrosion stands. They allow to exercise simulation tests under carbon dioxide corrosion conditions characteristic of the main gas fields of the Russian Federation. While using stands, the most intense corrosion effects were reproduced corresponding to the parameters and modes of movement of gas–liquid media: liquid flow loop and variable wetting of the gas pipeline wall, which lead to the prevention or destruction of films of corrosion products and the formation of general and local corrosion damage on steel. The ability to reproduce the nature of the movement of the liquid phase, thermobaric conditions and the chemical composition of water on both corrosion stands, corresponding to real conditions, makes it possible to simulate in the laboratory the dynamic corrosion effects inside the gas pipeline of untreated gas production and transport facilities. The main parameters affecting internal carbon dioxide corrosion are set and regulated in the test stands: temperature, partial pressure of carbon dioxide, mineral composition of the aqueous phase, dynamic conditions for the transfer of liquid phase flow through the pipeline. The analysis of corrosion products obtained after experiment using electron scanning microscopy and X-ray diffraction methods made it possible to study the influence of corrosion conditions on the morphology of their formation. It has been stated that to solve the problems of emulsion formation in the presence of corrosion inhibitors, either increasing the temperature or using demulsifiers is worth using. A study of the technology for using inhibitors showed that not all reagents have maintaining film-forming properties over time in the absence of constant dosing.

Keywords: corrosion stands, simulation tests, variable wetting, corrosion flow loop, carbon dioxide corrosion, corrosion products, local corrosion, gas pipeline

Int. J. Corros. Scale Inhib., 2024, 13, no. 2, 911-929
doi: 10.17675/2305-6894-2024-13-2-14

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