Silica flour also be called quartz flour is produced by breaking and grinning the mineral. Its main ingredient is SiO2, and in order to save the transition cost, most of the silica flour factory are set at the around of mine.
When the bottom hole circulating temperature is higher than 110℃, the strength of set cement becomes worse and worse. In order to prevent the strength degradation of set cement, 30%-40% (BWOC) of silica flour is need to adding into the cement. The SiO2 can react with the Ca(OH)2 released by cement hydration at high temperature and generate the CSH gel. The CSH gel can prevent the cement strength degradation at high temperature.
The general requirements of cementing to the silica flour:
Purity: SiO2 content ≥90%
Fineness： 130 mesh