热力采油条件下粉煤灰改善铝酸盐水泥石耐高温性能及作用机理研究

Study on Aluminates Cement with Fly Ash for Heavy Crude Oil Thermal Recovery in Well Cementation

硅酸盐类水泥石经热力采油后耐高温性能变差是诱导套管损坏和水泥环层间封隔失效的关键原因。和普通硅酸盐水泥相比,铝酸盐水泥具备更好的耐高温特性,但却存在温度敏感性强、高温养护后强度不高的缺点。实验通过在铝酸盐水泥中掺入粉煤灰并采用高能球磨方法重新制备水泥材料,采用XRD和SEM等测试方法,对粉煤灰材料改善铝酸盐水泥石耐高温特性和作用机理进行分析。结果表明:通过球磨方式加入粉煤灰材料不仅有利于水泥石低温强度的发展,而且能够明显改善铝酸盐水泥石的长期耐高温特性;其组分SiO2和铝酸盐水泥水化产物C3AH6发生反应,并生成C3ASH4等稳定相,使水泥石晶体结构排列致密,在高温下能够保持稳定,从而使得水泥石能够保持良好的力学性能,进而有利于保护套管和改善水泥环层间封隔性能,延长稠油热采井的生产寿命。

Silicate cement after high temperature stability turns out badly, which is the key reason to induce the damage of the casing and invalidation of the zonal isolation. Although aluminate cement enjoys better performance in high-temperature resistance compared with the ordinary silicate cement, it has the disadvantage of strong temperature sensitivity and weak intensity after high temperature curing. The experiment is through adding fly ash into the aluminate cement and adopting high energy ball milling to re-prepare cement material, by means of XRD and SEM, high-temperature resistance and the mechanism of the fly ash to improve aluminate cement was analyzed. The result shows that the fly ash added by way of ball milling not only contributes to cement stone low-temperature strength development, it improves the long-term high temperature property of the aluminate cement significantly. That the fly ash, added by ball , whose component SiO2 reacted with C3AH6, hydration product of aluminate cement, and generate C3ASH4 and other stable phase. The stable phase makes crystal structure of cement stone be tight arrangement and maintain stability at high temperature and thus keep good mechanical properties. Then it is in favour of casing protection, improves zonal isolation and extends the productive life of heavy oil thermal recovery wells.