Purpose

This paper aims to under the laboratory environment, the corrosion behavior of X80 pipeline steel in oilfield injection water in eastern China was studied by immersion test.

Design/methodology/approach

First, the corrosion product film was immersed in oilfield injection water and the effect on the corrosion behavior and the corrosion reaction mechanism were constantly observed during this period. The effect was displayed by potentiodynamic polarization curve and electrochemical impedance spectrums (EIS) measurements. Second, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used to observe and test the corrosion product film immersed in the oilfield water for 30 days.

Findings

The results indicate that the tendency of metal corrosion becomes weaker at an early stage, but strengthened later, which means the corrosion rate is accelerating. Besides, it is indicated by impedance spectroscopy that with the decreasing of the capacitance arc radius, the reaction resistance is reducing in this progress. Meanwhile, the character of Warburg impedance could be found in EIS, which means that the erosional components are more likely to penetrate the product film to reach the matrix. The corrosion product is mainly composed of the inner Fe₃O₄ layer and outer shell layer, which contains a large number of calcium carbonate granular deposits. It is this corrosion under fouling that produces severe localized corrosion, forming many etch pits on the metal substrate.

Originality/value

The experiment chose the X80 steel, the highest-grade pipeline steel used in China, to conduct the static immersion test in the injection water coming from an oilfield in eastern China. Accordingly, the corrosion mechanism and the effect of corrosion product film on the corrosion of pipeline steel were analyzed and discussed.

中文翻译：

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X80管线钢在华东地区油田注入水中的腐蚀行为

目的

本文旨在在实验室环境下，通过浸泡试验研究X80管线钢在华东地区油田注入水中的腐蚀行为。

设计/方法/方法

首先，将腐蚀产物膜浸入油田注入水中，在此期间不断观察对腐蚀行为的影响和腐蚀反应机理。该效应通过动电位极化曲线和电化学阻抗谱 (EIS) 测量显示。其次，采用扫描电镜、能谱仪和X射线衍射对油田水中浸渍30天的腐蚀产物膜进行观察和测试。

发现

结果表明，金属腐蚀趋势前期减弱，后期增强，腐蚀速度加快。此外，阻抗谱表明，随着电容弧半径的减小，反应电阻在此过程中减小。同时，在EIS中可以发现Warburg阻抗的特征，这意味着侵蚀成分更有可能穿透产品薄膜到达基体。腐蚀产物主要由内层Fe ₃ O ₄和外壳层组成，其中含有大量碳酸钙粒状沉积物。正是这种污垢下的腐蚀产生了严重的局部腐蚀，在金属基材上形成了许多蚀刻坑。

原创性/价值

试验选用国内最高等级的管线钢X80钢在华东某油田注入水中进行静浸试验。据此，分析讨论了腐蚀机理和腐蚀产物膜对管线钢腐蚀的影响。