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梁运培,刘 莹,邹全乐,等. 纳米氧化铝改性地面井固井水泥水化机制研究[J]. 煤炭科学技术,2024,52(7):68−78. doi: 10.12438/cst.2023-0951
引用本文: 梁运培,刘 莹,邹全乐,等. 纳米氧化铝改性地面井固井水泥水化机制研究[J]. 煤炭科学技术,2024,52(7):68−78. doi: 10.12438/cst.2023-0951
LIANG Yunpei,LIU Ying,ZOU Quanle,et al. Research on hydration mechanism of nano-alumina modified cementing cement[J]. Coal Science and Technology,2024,52(7):68−78. doi: 10.12438/cst.2023-0951
Citation: LIANG Yunpei,LIU Ying,ZOU Quanle,et al. Research on hydration mechanism of nano-alumina modified cementing cement[J]. Coal Science and Technology,2024,52(7):68−78. doi: 10.12438/cst.2023-0951

纳米氧化铝改性地面井固井水泥水化机制研究

Research on hydration mechanism of nano-alumina modified cementing cement

  • 摘要: 随着地面井固井技术发展加快,工程现场对于地面井固井水泥浆的早期流动性及凝结性能有了更高的要求。为了提高固井工程注水泥作业的顶替效率,改善固井工程现场作业应用情况,提出了纳米氧化铝颗粒改性固井水泥的方法,利用核磁共振技术对质量分数为0、0.05%、0.10%、0.15%及0.20%的纳米氧化铝改性水泥浆(水灰比为0.44)在不同水化龄期的水化反应变化特征进行了研究,探究了纳米氧化铝改性水泥的水相分布、物理结合水总信号量变化、峰形指数及迁移速率。结果表明:纳米氧化铝改性水泥浆在水化阶段的T2图谱会出现3个弛豫峰,分别对应絮凝结构填充水(0.1~10 ms)、毛细水(10 ms)、自由水(800~1000 ms);其物理结合水总信号随纳米氧化铝质量分数增加而逐步减少,其中质量分数为0.20%的纳米氧化铝改性水泥浆信号量减少速率最快;峰形指数呈现先上升后下降的趋势,当水化反应进行至600 min时,质量分数为0.20%的改性水泥浆变化速率最快,弛豫峰向短弛豫方向移动速率加快;结合迁移速率将纳米氧化铝改性固井水泥水化反应阶段划分,其水化机制分别作用在4个水化时期:①初始水化期(5~60 min),水化速率未发生明显改变;②加速水化期(60~600 min),纳米氧化铝使水泥浆中物理结合水转化为化学结合水所经历时间变短,水化进程加快,达到促进水泥水化的效果;③稳定水化期(600~1200 min),水泥体系趋于稳定;④延缓水化期(1200~1800 min),物理结合水转化为化学结合水速率变慢,水泥水化进程减慢。研究结论得到,纳米氧化铝改性水泥浆水化时期可以划分为4个阶段,分别起到物理填充、加速、稳定、延缓的作用。在加速期,纳米氧化铝促进水泥的早期流动,有利于水泥浆的泵送及流动,在延缓期,纳米氧化铝延缓水泥的进一步水化进程,利于发展早期强度。其中,质量分数为0.20%的纳米氧化铝改性水泥浆对于水泥水化进程影响最大,促进填充水向结合水的转化,在加速水化期间对于水泥浆水化反应加速程度最大,以此作为依据对现场固井水泥的制备及应用提供指导。

     

    Abstract: With the accelerated development of surface well cementing technology, the engineering site has higher requirements for the early fluidity and coagulation performance of surface well cementing water slurry. In order to improve the top-off efficiency of cement injection operation in cementing engineering and improve the application of cementing engineering field operation, the method of nanoalumina particles modified cementing cement was proposed, and the NMR technique was used to study the change characteristics of the hydration reaction of nanoalumina-modified cement slurries (with the water-cement ratio of 0.44) with the mass fractions of 0.00% wt, 0.05% wt, 0.10% wt, 0.15% wt, and 0.20% wt at different hydration ages were investigated to characterize the changes in hydration reactions, and to probe the aqueous phase distribution, changes in the total signal amount of physically bound water, peak shape index, and migration rate of the nanoalumina-modified cements. The results showed that the T2 patterns of nano-alumina-modified cement pastes at the hydration stage would show three relaxation peaks, corresponding to the flocculated structure-filled water (0.1−10 ms), capillary water (10 ms), and free water (800−1000 ms), respectively; and the total signal of the physically bound water decreased gradually with the increase of the mass fraction of nanoalumina, in which the nanoalumina-modified cement pastes with the mass fraction of 0.20%wt. Alumina-modified cement paste has the fastest reduction rate of signal; the peak shape index shows the trend of increasing and then decreasing, when the hydration reaction is carried out to 600 min, the modified cement paste with mass fraction of 0.20%wt has the fastest rate of change, and the rate of the relaxation peak moving to the short relaxation direction is accelerated; the combination of the migration rate of the nanoalumina-modified cementing cement hydration reaction stage division, and the hydration mechanism of its hydration mechanism respectively acted in the four Hydration period: ① initial hydration period (5−60 min), the hydration rate did not change significantly; ② accelerated hydration period (60−600 min), nano-alumina to make the physical binding water in the cement paste into chemical binding water in a shorter period of time, the hydration process is accelerated to achieve the effect of promoting the hydration of the cement; ③ stabilized hydration period (600−1200 min), the cement system tends to stabilize; ④ Delayed hydration period (1200−1800 min), the rate of conversion of physically bonded water to chemically bonded water slows down, and the hydration process of cement slows down. It was concluded that the hydration period of nanoalumina-modified cement paste can be divided into four stages, and nanoalumina plays the roles of physical filling, accelerating, stabilizing, and retarding for the cement paste, respectively. In the accelerating period, nanoalumina promotes the early flow of cement, which is conducive to the pumping and flow of cement paste, and in the retarding period, nanoalumina retards the further hydration process of cement, which is conducive to the development of early strength. Among them, the nano-alumina modified cement paste with a mass fraction of 0.20% wt has the greatest influence on the cement hydration process, promotes the conversion of filler water to bound water, and accelerates the hydration reaction of cement paste to the greatest extent during the accelerated hydration period, which serves as the basis for providing guidance for the preparation and application of cementing cements in the field.

     

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