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为探索抗腐蚀油井水泥浆体系的设计基础及途径,用X射线衍射仪、扫描电子显微镜、强度检测仪检测受腐蚀油井水泥石的产物、微观结构及抗压强度,研究调整井三次采油过程中油井水泥石的硫酸盐侵蚀问题。明确腐蚀作用方式,揭示抗压强度变化规律。结果表明:SO42-对水泥石产生的腐蚀类型为钙矾石-石膏混合型腐蚀;水泥石强度变化规律发生改变的临界腐蚀时间约为21d,腐蚀低于21d时,水泥石强度随腐蚀时间及SO24-浓度的增加而增大;腐蚀达到21 d后,水泥石强度低于未腐蚀水泥石,水泥石强度随腐蚀时间及SO24-浓度的增加大幅度下降;腐蚀21 d内,水泥石的强度随温度升高而增加;腐蚀28d时,最初随温度增加强度呈上升趋势,达到55℃后,随温度继续增加强度上升的幅度有所减弱。
In order to explore the design basis and approach of the corrosion resistant oil well cement slurry system, the product, microstructure and compressive strength of cement stone affected by corrosive oil well were studied by X-ray diffraction, scanning electron microscopy and intensity detector. Sulphate erosion of oil well cement stone. Clear the role of corrosion mode, revealed changes in compressive strength. The results show that the type of corrosion caused by SO42-cement stone is ettringite-gypsum mixed corrosion; the critical corrosion time when the change of strength of cement stone changes is about 21d; when the corrosion is lower than 21d, the strength of cement stone varies with the corrosion time and SO24- increased. When the corrosion reached 21 days, the strength of cement stone was lower than that of unglazed cement stone. The strength of cement stone decreased with the increase of corrosion time and SO24- concentration. The strength of cement stone With the increase of temperature, the initial intensity increased with the increase of temperature after 28 days of corrosion. When the temperature reached 55 ° C, the increase of intensity with temperature continued to decrease.