The nature of the chemical environment in oil and gas fluids such as produced water (PW) and soured oil or low‐oxygen environments plays a vital role in microbiologically influenced corrosion (MIC). H₂S and/or other forms of sulphur species in soured oils and PW are key factors in the corrosion and growth of microorganisms. To mitigate reservoir souring and subsequent corrosion, nitrate is injected to displace sulphate‐reducing bacteria with nitrate reducers. However, nitrates and the associated nitrogen species (eg, nitrite) impact the chemistry and microbial activity, and hence the corrosion potential in the system. This study investigates the PW chemical environment in light of sulphide and nitrite chemistry, and provides information towards understanding the chemical transformations and microbial relationships. The sulphide‐nitrite environment was studied as a function of temperature, pressure, nitrite level, oxygen‐using equilibrium, and kinetic model approaches. Equilibrium simulation predicted the formation of FeS, FeO(OH), and Fe₂O₃ as the key corrosion products, the amount of which varied depending on the chemistry and operating conditions. In experiments where nitrite was very low or absent, S⁰ was favoured over as the inlet H₂S concentration increased and FeS dominated with an increase in temperature. In the presence of nitrite, Fe₂O₃ was formed instead of FeO(OH) at temperatures above 50°C. The trend of the kinetic simulation of the sulphide‐oxygen reaction in seawater was in good agreement with the wet‐lab experiment in PW. The models can serve as tools to better understand and describe the chemical environment in PW systems.

中文翻译：

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石油和天然气设施中酸-亚硝酸盐-亚硝酸盐化学环境的模拟

油气流体（例如采出水（PW）和酸化油或低氧环境）中化学环境的性质在微生物影响的腐蚀（MIC）中起着至关重要的作用。高₂ S和/或酸化油和PW中其他形式的硫物质是微生物腐蚀和生长的关键因素。为了减轻储层的酸化作用和随后的腐蚀，需要注入硝酸盐以使用硝酸盐还原剂来替代减少硫酸盐含量的细菌。但是，硝酸盐和相关的氮物种（例如亚硝酸盐）会影响化学和微生物活性，进而影响系统中的腐蚀潜能。这项研究根据硫化物和亚硝酸盐化学方法研究了PW的化学环境，并为理解化学转化和微生物关系提供了信息。研究了硫化物-亚硝酸盐环境与温度，压力，亚硝酸盐水平，耗氧平衡和动力学模型方法的关系。平衡模拟预测了FeS的形成，FeO（OH）和Fe ₂ O ₃作为主要腐蚀产物，其数量根据化学性质和操作条件而变化。在亚硝酸盐非常低或不存在的实验中，随着入口H ₂ S浓度的增加和温度升高，FeS占主导地位，S ⁰受到了青睐。在亚硝酸盐存在下，形成Fe ₂ O ₃代替FeO（OH）在高于50°C的温度下。海水中硫化物-氧气反应动力学模拟的趋势与PW中的湿实验室实验吻合。这些模型可以用作更好地理解和描述PW系统中化学环境的工具。