塔河油田某含硫湿气管道腐蚀穿孔原因分析

Failure Analysis on Corrosion Perforation of Sulfur-containing Wet Gas Pipeline in Tahe Oilfield

塔河油田某含硫湿气管道近年来集中发生腐蚀穿孔,基于现场失效管样和积液样本,通过管材理化性能测试、腐蚀形貌表征、腐蚀产物分析和细菌基因测序等手段,揭示管道腐蚀穿孔的原因。分析结果表明:该失效管道材质各项性能均符合标准要求,发生腐蚀穿孔的主要原因是管道低洼处和爬坡段形成积液,H_(2)S/CO_(2)构成酸性腐蚀环境,其中H_(2)S腐蚀占主导。同时在腐蚀产物中培养出硫酸盐还原菌、铁细菌、腐生菌等细菌,且腐蚀穿孔部位存在细菌代谢分泌的胞外聚合物;对管道清出积液进行细菌基因测序,结果表明细菌类型以硫酸盐还原菌为主,因此认为腐蚀穿孔的主控因素为H_(2)S和硫酸盐还原菌腐蚀。

Corrosion perforation of a sour wet gas pipeline in Tahe oilfield has occurred intensively in recent years. Based on on-site pipe failure samples and effusion samples, tests of the physical and chemical properties of pipes, characterization of corrosion morphology, analysis of corrosion products and bacterial gene sequencing, were conducted to clarify the causes of pipe corrosion perforation. Results show that properties of the failed pipe sample material of the wet gas pipeline meet the requirements of the standard. The main cause of corrosion perforation is the formation of effusion in the low-lying part of the pipeline and the climbing section. H_(2)S/CO_(2)constitutes an acidic corrosive environment, of which H_(2)S corrosion is dominant. Sulfate reducing bacteria, iron bacteria, saprophytic bacteria and other bacteria were cultured in the corrosion products, and there were extracellular polymers secreted by bacteria metabolism at the corrosion perforation site. We sequenced the bacterial gene of the fluid cleared from the pipeline. Results show that the bacterial type was mainly sulfate reducing bacteria. Therefore, it was considered that the main controlling factors of corrosion perforation were H_(2)S and sulfate reducing bacteria corrosion.