为了预测油井管钢在高矿化度、含CO2的储层环境中可能发生的腐蚀, 为该储层推荐在开发周期内安全经济的材质, 采用高温高压反应釜研究了3Cr钢和13Cr钢在模拟储层环境中的腐蚀行为, 利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量色散X射线能谱(EDS)分析了3Cr钢和13Cr钢的腐蚀产物膜特征。从腐蚀速率、清理腐蚀产物后试样的表观特征、腐蚀产物的表面形貌、横截面腐蚀试样形貌和腐蚀产物化学成分方面探讨了3Cr钢和13Cr钢在CO2环境中的腐蚀特征随温度和含水率的变化规律及反应时间对其的影响。结果表明, 3Cr钢在CO2分压为0.2 MPa, Cl-含量139 552 mg/L的环境中会发生极严重腐蚀, 且试样表面产物膜在微观上分布不均匀, 存在局部不完整;13Cr钢发生轻度腐蚀, 在所测试样中未观测到点蚀, 即3Cr钢不适用于该高矿化度CO2环境而13Cr钢能够满足要求。

In order to evaluate the potential corrosion of casing and tubing in a high-salinity brine and CO2 environment, select material to ensure their safety and economy for full design life, the corrosion behavior of 3Cr and 13Cr steels in the simulated environment was investigated using an autoclave. The characteristics of corrosion products film of 3Cr and 13Cr steels were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive X-ray spectrometry(EDS). The rule of 3Cr and 13Cr steel corrosion behavior changing with temperature and water cut was discussed in the aspects of corrosion rate, surface morphology of corrosion scales, sectioning morphology and composition of corrosion scales and samples, surface characteristics of samples after clearing the corrosion scales. Serious corrosion and local incompletion of corrosion scales were found for 3Cr in 0.2 MPa CO2 and 139 552 mg/L Cl- corrosion environment. Mild corrosion behavior was examined in 13Cr steel and no pitting occurred for 13Cr. The experimental results indicated that 3Cr steel can′t meet the requirement for the high-salinity brine and CO2 environment but 13Cr steel can.