| 摘要: |
| 为考察含H2S/CO2酸性气井不同井段3种常用套管钢(T95钢、110SS-2Cr钢和825钢)的适用性及温度对其腐蚀行为的影响,利用高温高压釜在H2S分压0.55 MPa、CO2分压0.75 MPa、温度55 ～100 ℃条件下,对3种钢材的失重腐蚀性能进行了测试,并辅以扫描电镜观察腐蚀产物膜的微观形貌和能谱仪定性分析其化学成分,探讨了腐蚀机理。实验结果表明,模拟井筒腐蚀工况下,825钢腐蚀轻微,腐蚀速率远低于SY 5329-2012《碎屑岩油藏注水水质指标及分析方法》规定的腐蚀控制指标0.076 mm/a；T95钢和110SS-2Cr钢的腐蚀速率随温度的升高而增加,110SS-2Cr钢的耐电化学腐蚀性能远优于T95；随着温度的逐渐升高,T95钢和110SS-2Cr钢腐蚀产物膜变厚、结晶和结块趋势明显,主要成分是FexSy、FeCO3和含有少量Cr的化合物,110SS-2Cr钢腐蚀产物膜中,Cr含量比T95钢高,对基体的保护作用较强,因而在3个温度条件下的腐蚀速率均低于T95钢。结果 表明,T95钢用于油层套管井口段具有较好的经济性和适用性,825钢用在封隔器及以下井段具有较好的适用性,中间段油层套管采用110SS-2Cr钢具有较好的适用性。 |
| 关键词: H2S/CO2 油层套管 腐蚀速率 极化曲线 腐蚀产物膜 适用性评价 |
| DOI：10.3969/j.issn.1007-3426.2015.04.015 |
| 分类号:TE983 |
| 基金项目:国家自然科学基金“腐蚀与脉动冲击载荷共同作用下超高强度钻具疲劳损伤行为与控制机制研究”(51374177)。 |
|
| Applicability assessment of three different production casings in sour gas wells |
|
Zeng Dezhi1,Zhang Naiyan1,Chen Rui2,Wang Feng3,Shi Taihe1, Ren Chengqiang1
|
|
(1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation in Southwest Petroleum University, Chengdu 610500, China;2. Sichuan Kehong Petroleum Engineering Co., Ltd., Chengdu 613213, China;3. Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gasfield Company, Chengdu 610213, China)
|
| Abstract: |
| In order to assess the applicability and effect of temperature on corrosion behavior, the common specimens of three production casing steels(T95,0SS-2Cr and 825 steel) in different depths were subjected to acidic solution containing both 0.55 MPa H2S and 0.75 MPa CO2 at 55-100 ℃for 72 h in an autoclave, and micromorphologies and chemical compositions of corrosion products were obtained through scanning electron microscope (SEM) and energy dispersive X-ray (EDX), respectively. The weight-loss results show that the corrosion of 825 steel is slight according to the SY5329 standard, and the corrosion rate of 110SS-2Cr is lower than that of T95 steel, which explains its better anti-electrochemical corrosion performance. Besides, the corrosion rates of T95 steel and 110SS-2Cr steel increase as temperature rises. The microscopic analysis indicates that with temperature increasing, the corrosion products of T95 steel and 110SS-2Cr steel thicken and the tendency of crystallization and agglomeration is obvious, and the main chemical compositions are FexSy, FeCO3 and small amount of Cr. It is noted that the Cr content of 110SS-2Cr steel is higher than that of T95 steel, which accounts for the better protective effect and lower corrosion rate of 110SS-2Cr steel. Therefore, T95 steel is suggested to apply at the wellhead of production casing for its economy and practicality, the 825 steel can be used below the packer of production casing with its higher expense, 110SS-2Cr steel is appropriate to be used in the middle of production casing because of its poor SSCC resistance. |
| Key words: H2S/CO2 production casing corrosion rate polarization curves corrosion products applicability assessment |
