Evaluating eggshells as sustainable weighting agents in water-based drilling muds: A novel approach for enhanced efficiency and environmental consciousness

This study investigates the utilization of eggshells, a renewable material, as a weighting additive in water-based drilling muds with different exploring concentrations. The primary objectives were to assess the impact of eggshells on the rheological properties of drilling muds and to determine the optimal concentration of eggshells for achieving desired density and stability, drawing comparisons with calcium carbonate (CaCO3). Both eggshell powder (ESP) and CaCO3 effectively increase mud weight to the target density of 8.75 ppg at 30 g. Notably, ESP exhibits favorable rheological properties at 20 g, maintaining low plastic viscosity 2.7, consistent yield points 1.1, and gel strength comparable to CaCO3. Conversely, CaCO3 shows signs of potential deterioration at 30 g indicated by increased viscosity to 3.5 and decreased yield point to 0.5. ESP demonstrates superior filtration performance, displaying a progressive increase in cake thickness with increasing weight 1.32 mm to 3.12 mm compared to the slower cake build-up of CaCO3 0.92 mm to 2.9 mm. Both additives slightly elevate mud pH, potentially enhancing overall stability.