高酸性条件下元素硫对碳钢腐蚀的影响  

Corrosion of sulfur to carbon steel under the condition of high acidity

作　　者：高立新[1] 谷坛[1] 闫静[1] 余华利[1] 刘志德[1] 莫林[1] 

机构地区：[1]中国石油西南油气田公司天然气研究院

出　　处：《天然气工业》2015年第4期94-98,共5页Natural Gas Industry

摘　　要：天然气中硫含量超过一定温度、压力条件下的溶解度会导致气井中发生硫沉积,当元素硫大量沉积时,会堵塞流体通道.导致关井停产以及采输系统的严重腐蚀。为此,采用电化学极化测试、电化学阻抗测试和失重腐蚀及应力腐蚀测试的组合体系,全面系统地开展了元素硫存在条件下碳钢的腐蚀性能试验,进而模拟了元素硫在现场可能出现的沉积方式,弄清了元素硫沉积量、沉积方式对碳钢腐蚀性能的影响及腐蚀垢物的组成。结果表明:①元素硫与试样的接触程度和堆积形式对碳钢的腐蚀行为有重要影响;②元素硫的存在促进了碳钢的阴极反应;③硫的加入会改变腐蚀产物膜的结构,降低膜的电阻,增大腐蚀速率。最后结合电化学及失重腐蚀测试结果,明确了碳钢在含氯化物湿硫化氢环境中的腐蚀机理,为元素硫沉积工况下的材质选择、缓蚀剂应用、腐蚀监测及控制提供了技术支撑。Dissolution of sulfur in natural gas under certain temperature and pressure may lead to sulfur accumulation in gas wells. Massive deposition of sulfur may block the flowing channel of fluids and result in well shutdown and severe corrosion of production and transmission systems. In view of this, a composite system involving electrochemical polarization tests, electrochemical imped ance tests, weight-loss corrosion and stress corrosion tests was used to fully and systematically determine corrosion property of car- bon steel in the presence of sulfur. Furthermore, possible patterns of sulfur deposition on site were simulated to find out the compo sitions of corrosion products and the impact of sulfur deposits and deposition mode on the corrosion of carbon steel. Research results show that contact level between sulfur and the sample, together with the mode of sulfur accumulation may produce significant corrosion to carbon steel. The presence of sulfur may effectively accelerate the cathodic reaction of carbon steel and modify the structure of the film of corrosion products to reduce the resistance of the film, thus to accelerate corrosion. Finally, based on the results of electrochemical tests and weight-loss corrosion tests, the corrosion mechanism of carbon steel in such a chloride-containing environment with existence of wet hydrogen sulfide was identified. Relevant findings may provide a technical support for the selection of suitable materials, application of corrosion inhibitors, monitoring and control over corrosion in a sulfur deposition working condition.

关 键 词：高含硫天然气 元素硫 电化学 腐蚀 高酸性气田 碳钢 腐蚀控制 

分 类 号：TE980.1[石油与天然气工程—石油机械设备]