The growing global energy demand has intensified the need for sustainable solutions in hydrocarbon extraction. This study develops saltwater-based drilling fluids (SWBFs) incorpo-rating organic nanoparticles derived from coffee and lemon residues, characterized using IR, FTIR, and zeta potential analyses. The fluids adhere to the Herschel-Bulkley model, demonstrating non-Newtonian shear-thinning behavior. Statistical analysis confirmed the model¿s accuracy, with nanoparticles enhancing fluid stability and reducing filtrate volume to less than 7.5 mL in 30 minutes, while achieving a filter cake thickness of 0.8 mm. Mixing with 3.5% potassium chloride optimized rheological properties (yield point: 67.5 lb/100 ft²; plastic viscosity: 19 lb/100 ft²). Na-noparticles improved sealing and reduced permeability by plugging pores, further reinforcing mud structure. High-pressure and high-temperature tests revealed superior stability, making these fluids suitable for challenging drillin