Influence of olivine nano-silica on hydration and performance of oil-well cement slurries

This research provides an explorative study to determine the influence of a newly developed nano-silica obtained from the dissolution of olivine (OnS) as an additive in cementitious slurries for oil and gas wells. In this context, the heat evolution of normal density slurries of Class G oil-well cement and OnS, cured at different temperatures and atmospheric pressure, is examined by isothermal calorimetry. Under isothermal and isobaric conditions, the dependency of cement hydration kinetics on curing temperature is related to the activation energy and the degree of hydration of the cementing slurries. The apparent activation energy of the different slurries with OnS is estimated using static and dynamic methods. In addition, the effect of adding OnS in conventional density slurries is investigated using standard methods and procedures such as thickening time, rheology, settling and ultrasonic compressive strength determination, all prescribed by corresponding API standards. A beneficial effect of the OnS addition is found on stability, rheology and hydration degree of cementing slurries. Finally, the potential use of olivine nano-silica as an accelerator and enhancer of mechanical properties of oil-well cementitious composites is demonstrated. (C) 2016 Elsevier Ltd. All rights reserved.