【摘要】 针对塔里木油田库车山前超高压气井四开、五开尾管低返速固井水泥浆在注替过程中流动速度低、升温速度慢、可能影响其水化反应速度的问题,研究了低返速固井条件所致低搅拌速度对其超高密度水泥浆性能的影响及其作用机理。研究结果表明,在低返速固井条件下:水泥浆的水化反应速度及进程放缓,致使其稠化时间大幅延长,为此更容易导致封固段顶部水泥浆超缓凝的问题;悬浮稳定性基本不受影响,甚至有一定的改善;14 d抗压强度小幅降低,但28 d抗压强度基本不受影响;从而为国内外类似区块固井合理优选水泥浆体系、减少缓凝剂用量、降低水泥浆配方调试难度、减少封固段顶部水泥浆超缓凝的问题提供了新的理论依据和技术手段。更多还原

【Abstract】 During liner cementing in the fourth and fifth intervals of ultrahigh pressure gas wells drilled in the piedmont structure in Kuche county, Tarim basin, the hydration reaction speed of the cement is probably affected by its low return flowrate and slow temperature rise during pumping and displacement. To resolve this problem, laboratory study was conducted on the effect of low agitating speed resulted from low return flowrate on the performance of ultra-high-density cement slurries. The study result showed that at low return flowrate, the hydration reaction speed and the reaction process of a cement slurry become slow, resulting in great extension of the thickening time of the cement slurry, which in turn results in ultra-retarding of the top cement slurry in annular space. The suspension performance of the cement slurry was basically not affected by the low return flowrate, and to some extent, the low return flowrate even helped improve the suspension performance. The 14 d compressive strength of the set cement was slightly reduced, while the 28 d compressive strength of the set cement was basically not affected by the low return flowrate. The results of this study will provide a new theoretical basis and technical means to select cement slurry formulation for well cementing in similar conditions, minimize the amount of retarding agents required, make it easier to formulate cement slurry, and mitigate the ultra-retarding problem of the top cement in annular space.更多还原