油气环境下不同温度对3Cr钢腐蚀行为的影响

Effect of Different Temperatures on Corrosion Behavior of 3Cr Steel

研究了3Cr钢在饱和CO_(2)模拟油田井中不同温度下的腐蚀行为及腐蚀规律。利用高温高压釜对3Cr钢在不同温度(60,90,120,150,180℃)的饱和CO_(2)模拟油田溶液中浸泡6,12,24和72 h的失重腐蚀进行测试。采用XRD、SEM、EDS和XPS对3Cr钢腐蚀后的腐蚀产物物相结构、表面形貌、元素组成及腐蚀产物去除后基体表面的腐蚀形貌进行分析。实验结果表明3Cr钢在饱和CO_(2)模拟油田井中所形成的腐蚀产物主要由FeCO_(3)组成。温度不同导致基体发生不同程度的腐蚀,其主要由于腐蚀产物膜的形貌特征、晶粒尺寸及其致密度的变化。当测试温度为150℃时,腐蚀速率达到最小值。此外,在60~150℃温度区间,3Cr钢腐蚀产物厚度明显减小,在180℃厚度明显增加。去除腐蚀产物后,3Cr钢在不同温度下均发现有大量的点蚀坑,发生了严重的局部腐蚀。在150℃下钢的腐蚀坑明显比其他温度的腐蚀坑小,表现出优异的局部耐腐蚀性,从而降低了管道穿孔失效的风险。

The corrosion behavior and rules of 3Cr steel at different temperatures in saturated CO_(2)simulated oilfield wells were studied.The weight loss corrosion of 3Cr steel immersed in saturated CO_(2)simulated oilfield solutions at different temperatures(60,90,120,150,180℃)for 6,12,24 and 72 hours was tested using a high-temperature and high-pressure reactor.XRD,SEM,EDS,and XPS were used to analyze the phase structure,surface morphology,elemental composition,and corrosion morphology of 3Cr steel after corrosion products were removed,as well as the corrosion morphology of the substrate surface.The experimental results indicate that the corrosion products formed by 3Cr steel in saturated CO_(2)simulated oilfield wells are mainly composed of FeCO_(3).Different temperatures lead to varying degrees of corrosion on the substrate,mainly due to changes in the morphology,grain size,and density of the corrosion product film.When the testing temperature is 150℃,the corrosion rate reaches its minimum value.In addition,in the temperature range of 60 to 150℃,the thickness of corrosion products in 3Cr steel significantly decreases,while the thickness increases significantly at 180℃.After removing corrosion products,a large number of pitting pits were found in 3Cr steel at different temperatures,resulting in severe localized corrosion.At 150℃,the corrosion pits of steel are significantly smaller than those at other temperatures,exhibiting excellent local corrosion resistance,thereby reducing the risk of pipeline perforation failure.