CO2辅助蒸汽驱对四种钢的腐蚀性能影响模拟

CO₂辅助蒸汽驱是稠油开采的新型方式，但有关CO₂辅助蒸汽驱注气井中井下管柱CO₂腐蚀行为的研究较少。为此，利用高温高压釜模拟CO₂辅助蒸汽驱注气井筒工况，在CO₂分压为2 MPa，240 ℃的条件下，对4种常用的油套管钢进行了失重腐蚀挂片试验，得到了模拟工况下油套管钢的腐蚀速率，利用SEM观察了4种材质的微观腐蚀形貌，并采用SEM和EDS对4种管材的腐蚀产物进行了表征。结果表明，在实验条件下，4种材质的均匀腐蚀速率均小于油田的腐蚀控制指标（0.076 mm/a）；N80钢的腐蚀形态为均匀腐蚀，而3Cr、9Cr和13Cr钢的腐蚀形态为局部腐蚀；4种钢材的腐蚀速率均满足CO₂辅助蒸汽驱注气井筒腐蚀控制要求。

Simulation of the Effect of Corrosion Performance of Four Types Under CO2-assisted Steam Flooding Conditions

CO₂-assisted steam flooding is a novel method for heavy oil production. However, studies on CO₂ corrosion of downhole pipe in a high-temperature steam environment are relatively scarce. Therefore, in this study, the CO₂ corrosion behavior of oilfield pipe casing steel in a high-temperature steam environment was investigated using four types of oilfield pipe casing steel. A high-temperature, high-pressure autoclave was used to simulate the operating conditions during CO₂-assisted wellbore steam flooding. With a CO₂ partial pressure of 2 MPa and an operating temperature of 240℃, a weight loss coupon corrosion test was performed on four types of oilfield pipe casing steel, and the corrosion rates of the pipeline materials under the simulated operating conditions were obtained. Scanning electron microscopy, energy dispersive x-ray spectrometry, and x-ray diffraction were used to determine the morphology and composition of the corrosion products. The results show that under the experimental conditions, the uniform corrosion rates of the four types of materials were lower than the allowable corrosion rate for oil fields (0.076 mm/a). The corrosion morphology of N80 steel was uniform corrosion, while that of 3Cr, 9Cr, and 13CR steel were localized corrosion. The corrosion rates of all four steel materials met the corrosion control requirements for CO₂-assisted wellbore steam flooding.