Hydration performance of OWC pastes incorporating GO with various oxygen contents and sizes

This paper explores the reinforcement and toughening of oil well cement (OWC) by incorporating various oxygen content and size of graphene oxides (GO) at 50 °C, and then explores the mechanism of GO in OWC. Hydration heat evolution of OWC paste was tested using isothermal calorimetry. The hydration products and microstructure of OWC paste were examined using X-ray diffraction, thermogravimetric analysis, mercury intrusion porosimetry and scanning electron microscopy. Results suggest that the dispersion performance of GO in Ca(OH)2 solution (CH) enhanced by increasing of oxygen content and enlarging of size in GO. Higher oxygen content and larger size of GO result in lower fluidity and shorter thickening time of OWC paste. The hydration reaction of OWC paste accelerated by incorporating GO with larger size. A more densely packed microstructure and enhanced mechanical properties in GO-bearing OWC pastes are achieved, particularly in early hydration, which can be attributed to the formation of C–S–H with a comb-like structure and denser aggregated calcium hydroxide by incorporating of GO. The increased in oxygen content and enlargement in size of GO further enhanced this effect. Incorporating GO with higher oxygen content and larger size led to further improvements in the strength performance of OWC hardened paste.