Mixed Micromax and hematite-based fly ash geopolymer for heavy-weight well cementing

Ordinary Portland cement (OPC) has introduced different environmental and technical issues. Researchers tried either adding new materials to cement or developing alternatives for both technical and environmental challenges. Hematite as a weighting agent is used to increase cement slurry density. Heavy particles sedimentation in cement and geopolymer slurries is a serious issue which creates heterogenous properties along the cemented section. This work presents a new class of geopolymers using both hematite and Micromax as weighting materials for high density well cementing applications. The first system used only hematite while the other system used both hematite and Micromax. The main goal behind using Micromax with hematite is to check the possibility of eliminating the sedimentation issue associated with hematite in geopolymers. Moreover, the effects of adding Micromax on different FFA geopolymer properties were also evaluated. Different mixtures of retarder, retarder intensifier and superplasticizer were introduced to increase the thickening times of the developed geopolymer systems. The results showed that adding Micromax to hematite decreased the average density variation from 12.5% to almost 3.9%. Micromax addition reduced plastic viscosity by 44.5% and fluid loss by 10.5%. Both systems had a close performance in terms of strength, elastic properties, and permeability. The thickening time was 390 min for the hematite system and 300 min for the mixed system using the proposed additives mixtures.