Coconut Shells, Periwinkle Shells, Snail Shells, and Eggshells as Calcium Carbonate Weighting Materials Additives to Improve Performance of Water-Based Mud as Drilling Fluid

Drilling in highly permeable zones presents significant challenges, particularly the influx of formation fluid due to low hydrostatic pressure from the drilling fluid. Hence, the objective of this paper was to evaluate 74-micron mesh sized coconut shells, periwinkle shells, snail shells, and eggshells as calcium carbonate (CaCO3) weighting materials additives to improve performance of water-based mud (WBM) as drilling fluid using appropriate standard techniques. Data obtained show all materials met the American Petroleum Institute (API) specifications for pH (9.5-12.5), with CaCO3 achieving the highest value of 11.2. Density measurements for all additives fell within the API standard range of 8.50- 9.60 ppg Results indicate that the biomass-derived calcium carbonate materials enhance various drilling mud parameters, including pH, sand content, rheological properties, and filtration characteristics, with a notable improvement in drilling fluid density. However, while the materials showed acceptable sand content, eggshells exceeded the API limit. The rheological properties were not significantly improved despite meeting plastic viscosity standards, and none conformed to the API specification for fluid loss