盐穴地下储气库氮气阻溶管柱腐蚀寿命预测

为分析盐穴地下储气库氮气阻溶条件下管柱的氧腐蚀情况,预测其服役寿命,通过室内高温高压腐蚀失重试验,研究氮气纯度对N80管材的气液两相腐蚀规律,并结合X射线荧光光谱(XRF)分析、X射线衍射(XRD)分析、 扫描电镜(SEM)分析等表面分析技术对腐蚀产物进行表征分析.最后基于均匀腐蚀速率对管材的腐蚀寿命进行预测.研究结果...

Corrosion Life Prediction of Nitrogen Anti-soluble Pipe String in Salt Cavern Underground Gas Storage

In order to analyze the oxygen corrosion of the pipe string under the nitrogen anti-soluble condition in the salt cavern underground gas storage and predict its service life,the high temperature and high pressure corrosion weight loss test was carried out in laboratory to study the gas-liquid two-phase corrosion law of nitrogen purity on N80 tubular goods;then,combined with surface analysis techniques such as X-ray fluorescence spectrum(XRF)analysis,X-ray diffraction(XRD)analysis and scanning electron microscopy(SEM)analysis,the corrosion products were characterized and analyzed;and finally,based on the uniform corrosion rate,the corrosion life of the tubular goods was predicted.The study results show that under the experimental conditions,the liquid corrosion rate decreases with the increase of nitrogen purity;when the nitrogen purity is in the range of 78%~95%,the liquid corrosion is serious,and the corrosion prevention of tubular goods needs to be considered;in the liquid nitrogen environment(nitrogen purity is 99.9%),the liquid corrosion rate is lower than the oilfield corrosion control index 0.076 mm/a,the corrosion effect of the tubular goods needs not be considered;as the nitrogen purity increases,the service life of inner and outer pipes under different working conditions increases gradually;the 99.9%,95.0%,90.0 and 78.0%nitrogen purity all can meet the pipe string strength of 3 a cavity building period;and for 5 a cavity building period,the lower limit of nitrogen purity is proposed to be 90.0%.The study results provide a strong basis for the cavity building of salt cavern underground gas storage.