集输管线腐蚀检测与安全性分析——以鄂尔多斯盆地靖边气田为例

鄂尔多斯盆地靖边气田于1997年建成投产，天然气中携带H₂S、CO₂等酸性气体及高矿化度地层水等腐蚀性介质。为确保集输管线的安全运行，近年来，利用外腐蚀检测技术、取样分析检测技术和智能漏磁内腐蚀检测技术对集输天然气管线开展了腐蚀检测作业。检测结果表明，该气田集气干线腐蚀速率为0.06～0.103 mm/a，集气支线腐蚀速率为0.08～0.127 mm/a，集输管线阴极保护效果及管道外防腐层质量较好，管道腐蚀较轻，均能通过安全评定，不影响管线的正常运行。同时，运用修正的B31G准则、Shell 92法、GB 50251、Newton-Raphson公式等安全性分析与评价方法对检测管线进行了安全性分析，结果表明，集气干线、支线最小失效压力分别为12.5 MPa、8.53 MPa，均高于管线的工作压力5.0 MPa，集输管线服役状态良好，运行安全。该检测与分析结果，为靖边气田集输管线的安全管理提供了保障。

Corrosion detection and safety evaluation & analysis of flow and transport lines:A case study from the Jingbian Gas Field, Ordos Basin

Corrosive media like H₂S (691 mg/m³ on average), CO₂ (5%), etc., and high salt water have been carried with the natural gas produced from the Jingbian Gas Field, Ordos Basin, which was put into production in 1997. Therefore, it is quite essential to prevent and control the corrosion in the flow and transport lines in this field. In recent years, external corrosion detection, sample analysis, and internal corrosion detection by use of the intelligent magnetic flux leakage (MFL) tools have been adopted to inspect different pipelines in this field. The results show that the corrosion rates of arterial flow lines are 0.06 0.103 mm per year, while those of branch lines are 0.08 ~ 0.127 mm per year; a better quality is found in those lines with the cathodic protection and external coating protection; the corrosion degree is so light that those lines can all go through safety assessment and be kept under normal operation. Meanwhile, safety evaluation and analysis have been made of the inspected lines by use of the Shell 92, ASME B31G (the modified version), and GB50251 guidelines as well as the Newton Raphson formula. The results show that the minimum failure pressure of arterial and branch lines is 12.5 and 8.53 MPa respectively, which are both higher than the working pressure of 5.0 MPa; and the lines in this field are all kept in good service. This study provides guarantee for safety management of flow and transport lines in the Jingbian Gas Field.