Cailiao Baohu (Sep 2022)

Study on Corrosion Behavior of Gathering Pipeline Pipe in Tahe Oilfield

  • WEN Xiaohu, SHI Xin, WEN Ninghua, WANG Maomao, WEI Xiaojing, CHEN Yingfeng, LIU Dongmei

DOI
https://doi.org/10.16577/j.issn.1001-1560.2022.0245
Journal volume & issue
Vol. 55, no. 9
pp. 46 – 54

Abstract

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For solving the problem of frequent corrosion failures of surface pipelines in Tahe Oilfield, the high temperature and high pressure reactor was used to simulate the service environment of the surface pipelines, and the electrochemical test and corrosion coupon evaluation test of different pipes were carried out. The corrosion variation conditions of such pipes in the service environment of the surface gathering pipeline in Tahe Oilfield were clarified through the electrochemical performance analysis, microscopic morphology observation and corrosion rate calculation. Results showed that under the condition of 60 ℃ and 50% CO2, the corrosion of 20# and 1Cr steels showed typical anode dissolution characteristics, while 304 pipes passivated. Additionally, 304 pipes had the largest polarization resistance, followed by 1Cr and 20# steels; With the increase of temperature and CO2 content, the corrosion of the three pipes was aggravated, and the overall corrosion rate showed an increasing trend. Under the condition of 70℃ and 70% CO2, 20# and 1Cr steels exhibited localized corrosion in gas - liquid two - phase, the 20# steel had slight local corrosion in the gas phase environment, and 1Cr steel had a higher risk of local corrosion. The 304 stainless steel uniformly corroded in gas - liquid two - phase with a relatively low corrosion rate. The corrosion products in gas phase environment were mainly FeCO3 and a small amount of FeS, and the corrosion products in the liquid phase environment were mainly CaCO3 and FeCO3. The pipe material corroded locally in gas phase environment due to the condensate water, and the main corrosion mode in liquid phase environment was carbon dioxide corrosion. Therefore, through the comprehensive research on the corrosion behavior of the three materials, it could be concluded that 304 and 20# pipes could be used as the surface gathering system pipes of Tahe Oilfield, and attention should be paid to the local corrosion risk when 20# steel was used in harsh environments.

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