Hydration Kinetics Study of Class G Oil-Well Cement and Olivine Nano-silica Mixtures at 20–60 °C

Abstract

In this study the heat evolution of standard density slurries (1.89 g/cm3) of Class G oil-well cement and olivine nano-silica additions (0.5–2.0 % bwoc), cured under different temperatures (20–60 °C) and atmospheric pressure, were examined by isothermal calorimetry. Under isothermal and isobaric conditions, the dependency of cement hydration kinetics on curing temperature is related to the activation energy of the cementing slurry. The estimated apparent activation energy of the different slurries with olivine nano-silica varies from 38 to 44 KJ/mol using a dynamic method, at the temperature range of 20–60 °C. It is demonstrated that the addition of olivine nano-silica increases the rate and the heat of hydration of oil-well slurries. These effects are temperature dependent. Finally, comparable hydration degrees were obtained between slurries containing 0.5 % bwoc of olivine nano-silica and 10 % bwoc of oil-well grade micro-silica (mS).