Microemulsion‐Based Drilling Fluids Incorporating Seashell Residue Powder: A Sustainable Approach to Fluid Loss Control

ABSTRACT This study investigates the development and performance of microemulsion‐based drilling fluids (MDFs) incorporating seashell residue powder (SSRP) as a potential substitute for conventional calcium carbonate in fluid‐loss control applications. Microemulsions were formulated using pine oil, the nonionic surfactant laureth‐10, and a glycerol/water solution, selecting oil‐in‐water (O/W) systems from a ternary phase diagram to ensure thermodynamic stability. The MDFs were characterized through standardized tests following the American Petroleum Institute (API) Recommended Practices to evaluate rheological behavior, aging resistance, filtration performance, thermal stability, pH, density, and filter cake permeability. The O/W microemulsion‐based systems exhibited high emulsion stability, with SSRP achieving fluid‐loss control comparable to commercial CaCO 3 , resulting in filtrate volumes of 1.5 and 1.3 mL, respectively. Surfactant adsorption onto clay and mineral surfaces led to the formation of dense, low‐permeability filter cakes, effectively minimizing filtrate invasion and pore development. All formulations demonstrated shear‐thinning behavior, accurately described by Bingham's Plastic Model, confirming their predictable flow response under shear stress. Overall, the results demonstrate that SSRP is a technically viable additive to replace commercial calcium carbonate in MDFs, providing an effective alternative use for seashell waste and preventing its improper disposal.