Evaluation of hematite and Micromax-based cement systems for high- density well cementing

Weighting materials such as hematite are used to increase the density of cement slurries for different applications. Density variation (DV) across the cement column due to heavy particles sedimentation is a critical problem that results in disruption in hardened cement properties such as porosity and strength. In this work, two heavy-weight cement systems using Micromax and hematite were evaluated in terms of rheological properties, fluid loss, compressive and tensile strength, petrophysical properties and dynamic elastic properties. This study especially focused on the sedimentation problem associated with using hematite as a weighting material in well cementing. Different advanced techniques such as scanning electron microscope (SEM), nuclear magnetic resonance (NMR), and computerized tomography (CT) scan were used to investigate the potentiality of using Micromax to solve this problem. NMR, and CT-scan confirmed the results of the conventional method of DV that showed that the Micromax-weighted cement is more homogeneous with only 1.4% DV vertically along the samples. The Micromax-based system had lower porosity and permeability as compared to the hematite-based system. The Micromax-based cement was more flexible than the hematite-based system in terms of the elastic properties. Both cement systems showed a very similar performance regarding rheological and fluid loss properties. Micromax proved its potentiality to minimize the sedimentation problem encountered while maintaining the other recommended cement characteristics.