超细水泥在储气库老井封堵中的研究与应用

摘要

超细水泥的粒径比常规水泥的粒径小,在封堵过程中可以进入到常规水泥不能进入的裂缝中,尤其适合于低孔、低渗油藏的封堵作业.超细水泥的比表面积越大,水化反应速度越高,水泥颗粒与水的接触面大,使水泥石内部的极小空隙变为不连通,从而很大程度地提高了水泥石的抗渗性能；水泥粒径越小,通过窄缝的能力越强,超细水泥通过0.25 mm窄缝的体积百分比均在95％以上.但是,由于超细水泥颗粒细,比表面积大、水化速度快,胶凝和稠化时间短,对水泥浆的性能影响比较大.针对这些问题,结合京58储气层物性,通过对超细水泥的细度和粒径分布进行分析,优选出了适合储气库老井封堵的超细水泥,并研究和开发了适应老井封堵用的超细水泥浆体系.该体系在京58区块中应用,取得良好效果.%The grain size of superfine cement is much smaller than conventional cement, which is good for sealing of low porosity and permeability reservoirs. The surface to volume ratio of superfine cement is big, so the impermeability of the cement stone can be improved sharply, and more than 95% of volume ratio can pass by the 0.25 mm fracture, however, the thickening time is shortened by the superfine cement. A superfine cement slurry system for old well plugging back is developed, based on the grain distribution analysis of superfine cement and reservoir physical characteristics of Jing58, and the application in Jing58 block is successful.