油田埋地碳钢管道外腐蚀行为研究

External Corrosion of Buried Carbon Steel Pipelines in Oilfields

刘晓 陈艳华 钟卉元 李六军 陈宇

LIUXiao CHENYanhua ZHONGHuiyuan LILiujun CHENYu

华北理工大学建筑工程学院, 河北 唐山 063210 唐山市排水工程技术研究中心, 河北 唐山 063210 北京华远意通热力科技股份有限公司, 北京 丰台 100070 中国石油大庆油田有限责任公司第九采油厂规划设计研究所, 黑龙江 大庆 163853

College of Civil and Architectural Engineering, North China University of Science and Technology, Tangshan, Hebei 063210, China Drainage Engineering Research Center of Tangshan, Tangshan, Hebei 063210, China Beijing Huayuanyitong Thermal Technology Co. Ltd., Fengtai, Beijing 100070, China Planning and Design Institute of No.9 Oil Production Company, Daqing Oilfield Company Ltd., PetroChina, Daqing, Heilongjiang 163853, China

针对大庆油田龙虎泡作业区埋地碳钢管道外腐蚀较为严重的情况，通过检测埋管防护层破损点周围土壤的物理、化学性质和硫酸盐还原菌（SRB）数量，分析土壤的腐蚀性。采用扫描电镜能谱（SEM-EDS）、X射线衍射（XRD）和红外光谱（IR）等技术对管道外壁腐蚀物的形貌、元素组成和矿物成分等进行了表征和分析。借助动电位极化曲线和电化学阻抗谱（EIS）进一步研究了埋地碳钢管道外壁在土壤浸出液中的腐蚀行为。结果表明，作业区潮湿的盐碱性土壤环境和复杂多变的土壤性质使该地区埋地碳钢管道发生腐蚀；腐蚀产物主要包括FeO和FeOOH，其中FeOOH位于外层，FeO位于内层；腐蚀产物通过参与阴极反应或充当大阴极来加剧管道腐蚀。

With regard to the relatively severe external corrosion of buried carbon steel pipelines in the Longhupao operation zone of the Daqing Oilfield, soil corrosivity was analyzed by determining the physical properties, chemical properties, and counts of sulfate-reducing bacteria of soil around coating defects on the buried pipelines. The morphology, elemental composition, and mineral content of corrosion products on the external walls of the pipelines were characterized and analyzed using techniques such as scanning electron microscopy-energy dispersive x-ray spectrometry, x-ray diffraction, and infrared spectroscopy. By means of potentiodynamic polarization curves and electrochemical impedance spectroscopy, the corrosion behavior on the external walls of buried carbon steel pipelines in soil extract solution was further investigated. The results indicated that the corrosion of buried carbon steel pipelines in the zone was caused by the wet saline-alkali soil environment as well as complex and varying soil properties. The corrosion products were mainly FeO and FeOOH, located in the inner and outer layers, respectively. The corrosion products contributed to cathodic reactions or acted as large cathodes, further aggravating pipeline corrosion.

10.11885/j.issn.1674-5086.2017.05.05.04