Evaluation of Granite Waste Powder as an Oil-Well Cement Extender

The granite industry generates huge amounts of waste powder. The granite waste powder (GWP) has a lower specific gravity in comparison with Portland cement and is rich in silica and alumina. These properties suggest that the GWP could be a candidate for lightweight cement design; however, such a study has not been explored. This study investigates the possibility of using GWP in a lightweight cement system and the combined effect of the GWP and perlite. The cement-GWP binary slurries were prepared at approximately 13.5 lbm/gal (1.62 g/cm³) by replacing cement with 0, 5, 10, 15, and 20% GWP by weight of binder. About 10 to 15% of perlite was included in cement-GWP-perlite ternary blends. The slurries were cured at a bottomhole static temperature of 163 °F and bottomhole pressure of 2600 psi/ atmospheric pressure. X-ray diffraction was used to evaluate the hydration and pozzolanic processes. The impact of GWP was predominantly the result of its filler effect; however, there is the likelihood of a small pozzolanic effect. The inclusion of perlite into the cement-GWP composite resulted in improved strength at very early times due to the high pozzolanic activity of the perlite, allowing for the design of optimized lightweight systems using only 50–60% Portland cement.