Dynamic evaluation of sugarcane drainage water as a sustainable low-salinity injection brine for enhanced oil recovery: integrated micromodel visualization and coreflooding study

Abstract The increasing scarcity of freshwater resources and the environmental challenges associated with agricultural wastewater disposal have intensified the search for alternative injection fluids for enhanced oil recovery (EOR). This study establishes a new dynamic framework for evaluating untreated sugarcane drainage water as a naturally occurring low-salinity injection brine for EOR, extending our previous compatibility-based work to direct pore- and core-scale displacement evaluation. Unlike our previous work, which focused mainly on the physicochemical compatibility of drainage water with crude oil, the present study evaluates its displacement performance under dynamic conditions. By combining pore-scale micromodel visualization with dolomite coreflooding, the study links recovery behavior with interfacial interactions, wettability, and fluid displacement at both pore and core scales. Micromodel experiments revealed the coupled influence of injection rate and brine chemistry on recovery performance. At 10 mL min –1 and after 5 pore volumes, final oil recovery increased from 46.26% with distilled water to 61.69% and 76.38% with drainage waters 1 and 2, respectively. Pore-scale observations indicated that this improvement was associated with reduced interfacial tension, wettability alteration from oil-wet toward less oil-wet conditions, and stable emulsion formation. Coreflooding at 80 °C confirmed the same trend, with final oil recovery increasing from 29% with distilled water to 43% and 45% with drainage waters 1 and 2, respectively. The superior performance of drainage water 2 was consistent with its favorable ionic composition and greater wettability alteration. Overall, the results demonstrate the potential of untreated sugarcane drainage water as an alternative low-salinity injection source while providing a beneficial reuse pathway for agricultural drainage water.