Biomass ashes as a new additive for eco-friendly drilling fluids: chemical characterization and evaluation of rheological and filtration properties

The açaí industry generates 1,300,000 tons of primary waste (açaí pits) annually, part of which is used to produce electricity, generating secondary waste (açaí ash) that is often discarded in rivers or on land. Meanwhile, the oil industry seeks solutions to reduce the environmental impacts of its exploratory processes. This research addresses both challenges by reusing açaí ash as an eco-friendly, low-cost additive for water-based drilling fluids. Chemical characterization <i>via</i> X-ray fluorescence (XRF) showed the ash is rich in potassium, phosphorus, silicon, and calcium. Fourier-transform infrared spectroscopy (FTIR) detected phosphate groups linked to carbon chains, while scanning electron microscopy (SEM) revealed an amorphous structure with high polydispersity. Açaí ash was tested as a thickening agent in eight fluid formulations, using particle sizes smaller and larger than 300 µm, compared to CaCO₃. Results indicated that replacing CaCO₃ with açaí ash increased plastic viscosity by 30% and yield point by 28%, with pH values between 8 and 11. Filtrate volumes ranged from 5.2 to 7.0 mL, compared to 7.3 mL for CaCO₃. These findings demonstrate that açaí ash improves drilling fluid properties and mitigates environmental impacts, providing a sustainable solution for both industries.