Core flood and wettability alteration investigation of lignin nanoparticles in the presence of salts for enhanced oil recovery

Oil remains the most important energy sources and chemical raw materials. Efficient extraction of hydrocarbons using ecofriendly chemicals is essential for sustainable development. Lignin, a natural, abundant, and green material, shows great potential for such applications. Lignin nanoparticles (LNPs), with their high specific area, are effective emulsion stabilizers and hold promise for enhanced oil recovery (EOR). In this study, LNPs approximately 100 nm in diameter were prepared using an eco-friendly anti-solvent precipitation process from an aqueous alkali lignin solution, with hydrochloride acid serving as the anti-solvent. The physical chemical properties of the LNPs were evaluated. including wettability alternation, zeta potential, interfacial tension, emulsion stability. To assess their applicability for oil recovery, experiments were conducted to investigate crude oil removal/washing from silica glass surface and core flooding using a 0.05% LNPs nanofluid on crude oil saturated core samples. The results showed that LNPs achieved excellent oil removal/washing (91%) from silica surfaces, primarily due to the alteration of wettability of surfaces. Moreover, tertiary flooding with LNPs recovered up to 14% additional residual oil from core samples. Reduced injection pressure was also observed in lower permeability cores. This research provides new insights into the application of the eco-friendly lignin nanomaterial for enhanced oil recovery, offering a sustainable solution for the oil industry.