Abstract Produced water found in the exploitation and transport of oil and gas is composed by many contaminants such as chloride, CO2 and H2S. Nowadays, a very limited amount of studies in the literature have explored the effects of different salt concentration on the both corrosive mechanisms of CO2 and H2S. The aim of this work was to analyze the temperature and Cl− concentration influence on corrosion behavior of API X65 steel exposed to a CO2 saturated only and CO2/H2S (from thiosulfate ions) environments. The evaluation was carried out through Electrochemical Impedance Spectroscopy (EIS), Linear Polarization Resistance (LPR) and weight loss tests at 90 °C and 120 °C with 0.1% wt. and 3.5% wt. NaCl. The samples characterization was performed by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The results showed that sodium chloride made it difficult to precipitate FeCO3 films at 90 °C both in environment with CO2 only and with thiosulfate-CO2. In the environments with addition of thiosulfate, the higher concentration of sodium chloride, favored the formation of the more stable sulfide films revealing pyrite as the product. The higher temperature favored the formation of both FeCO3 and FeS films, for all conditions tested. Sulfide films formed at 120 °C were identified as pyrite and greigite, in which are sulfide layers with better protective characteristics. However, due to the imperfections and brittleness of these films, it was not possible to have a significant reduce of the corrosion process in the steel. Only the condition with higher sodium chloride concentration at 120 °C, corrosion rates were reduced due to higher precipitation of mackinawite films together with more stable phases such as pyrite.

中文翻译：

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不同盐水和温度对API X65碳钢中CO2和H2S竞争降解机制的影响

摘要 油气开采和输送过程中的采出水由氯化物、CO2、H2S等多种污染物组成。如今，文献中非常有限的研究探讨了不同盐浓度对 CO2 和 H2S 两种腐蚀机制的影响。这项工作的目的是分析温度和 Cl− 浓度对 API X65 钢在仅饱和 CO2 和 CO2/H2S（来自硫代硫酸根离子）环境中腐蚀行为的影响。评估是通过电化学阻抗谱 (EIS)、线性极化电阻 (LPR) 和重量损失测试在 90 °C 和 120 °C 下进行的，重量为 0.1%。和 3.5% 重量。氯化钠。通过扫描电子显微镜 (SEM) 和 X 射线衍射 (XRD) 进行样品表征。结果表明，氯化钠使得在只有 CO2 和硫代硫酸盐-CO2 的环境中在 90 °C 下都难以沉淀 FeCO3 薄膜。在添加硫代硫酸盐的环境中，较高浓度的氯化钠有利于形成更稳定的硫化物膜，显示出黄铁矿作为产物。对于所有测试条件，较高的温度有利于 FeCO3 和 FeS 薄膜的形成。在 120 °C 下形成的硫化物膜被确定为黄铁矿和灰铁矿，其中硫化物层具有更好的保护特性。然而，由于这些薄膜的缺陷和脆性，不可能显着减少钢中的腐蚀过程。只有在 120 °C 时氯化钠浓度较高的条件，