Low hydration exothermic well cement system: The application of energy storage microspheres prepared by high-strength hollow microspheres carrying phase change materials

Abstract An energy storage microsphere, prepared by encapsulating phase change materials in high-strength hollow microsphere, was proposed in this paper. The research objective was designed to utilise energy storage microspheres (ESM) in the cement mixture to achieve low hydration exothermic, without negatively affecting other properties. In this study, ESM were prepared and the difference between sealed and unsealed ESM was analysed. Further, the hydration exothermic of the cement, with sealed ESM, was tested and the influence of sealed ESM on the strength and other basic properties of the cement were evaluated. Results showed that resin sealed the ESM. Under 20 °C curing, sealed ESM were found to reduce the heat released during cement hydration process and improve the rheological properties of the cement slurry. The sealed ESM were observed to have no negative impact on strength and the basic properties, such as density, settlement stability, and rheology, of the cement for amount less than 20%. The scanning electron microscope results showed that the interface between sealed ESM and the cement matrix was stable. This novel material made the oil-well cement applicable for natural gas hydrate cementing in deep water.