腐蚀时间对N80钢在0.5 MPa CO_(2)模拟油田水下腐蚀行为的影响

Effect of Corrosion Time on the Corrosion Behavior of N80 Steel in 0.5 MPa CO_(2) Simulated Oilfield Water

目前,关于腐蚀时间对N80油套管钢在CO2环境下的腐蚀行为的影响研究较少。利用SEM、XRD、EDS和电化学测试分析方法,研究了腐蚀时间对N80钢在70℃、0.5 MPa CO2的模拟油田水中的腐蚀行为的影响。结果表明:腐蚀时间通过影响腐蚀产物膜的成分、厚度和致密性从而影响其腐蚀行为。在腐蚀起初的24 h,试样表面仅产生不规则孤立的FeCO3晶粒,产物膜尚未完全在基体表面覆盖。48 h后,FeCO3晶粒开始长大并连成片形成均匀致密的腐蚀膜。在腐蚀进行96 h后,CaCO3晶粒开始在产物膜上析出,FeCO3晶粒持续长大。在腐蚀进行192 h时,大量的CaCO3晶粒覆盖在FeCO3晶粒表面,与FeCO3共同组成致密的产物膜。随着腐蚀时间延长,腐蚀膜持续增厚且致密,腐蚀速率持续降低。

At present,the effect of corrosion time on the corrosion behavior of N80 oil casing steel in 0.5MPa CO2environment has less been studied.By the means of SEM,XRD,EDS and electrochemical test,the effect of corrosion time on the corrosion behavior of N80 steel in simulated oilfield water with 0.5 MPa CO2 at 70℃.Results showed that the corrosion time affected the corrosion behavior through influencing the composition,thickness and compactness of the corrosion product film.In the first 24 h of corrosion,only irregular and isolated FeCO3 grains were produced on the surface of samples,and the product film was not completely covered on the substrate.After 48 h of corrosion,FeCO3 grains grew and connected with each other to form an uniform and dense corrosion film.After 96 h of corrosion,CaCO3grains began to precipitate on the product film,and FeCO3 grains continued to grow.At 192 h of corrosion,a large number of CaCO3 grains covered the surface of FeCO3grains,which formed a dense product composite film.With the increase of corrosion time,the corrosion film continued to be thicker and denser,and the corrosion rate continued to decrease.