Novel PLA-Henna composite for sustainable tertiary enhanced oil recovery

Enhanced oil recovery (EOR) remains a critical focus for the petroleum industry, aiming to overcome the challenges of residual oil mobilization and maximize hydrocarbon recovery in increasingly complex reservoirs. This study introduces an innovative approach using synthesized Polylactic Acid (PLA)/Henna composites as an environmentally sustainable additive to enhance oil recovery through mechanisms such as interfacial tension (IFT) reduction, wettability alteration, and physical sweeping for improved fluid sweep efficiency. The composite was synthesized using extrusion techniques to ensure a uniform filler dispersion and was extensively characterized through FTIR, SEM, and EDS analyses. Brines, including seawater (SW), formation water (FW), and PLA-Henna-modified SW, were formulated to simulate actual reservoir conditions. Experimental analyses included IFT measurement using the pendant drop method, wettability studies using contact angle measurements, and core flooding experiments to assess EOR performance. Experimental findings revealed that the optimal PLA-Henna concentration was 2 wt%, which achieved significant IFT reductions (to 27 mN/m in SW). The composite also altered rock wettability from oil-wet to water-wet with pronounced effects in SW brine, where contact angles reduced from 142 to 89°. Core flooding experiments highlighted an increase in oil recovery factors, with PLA-Henna-modified SW yielding the highest recovery (85%) compared to FW (49.7%) or SW (61%). These advancements emphasize PLA/Henna composites' potential for sustainable EOR applications, ensuring improved recovery outcomes while utilizing biodegradable, eco-friendly materials.