Application of biosynthesized nanoparticles in chemical enhanced oil recovery: Main mechanisms, recent advances, challenges, and opportunities

Nanoparticles are increasingly used in chemical enhanced oil recovery (CEOR) due to their ability to improve oil recovery by altering reservoir rock and fluid properties. These nanoparticles, which have unique physical and chemical traits, can be synthesized chemically or biologically. Biological synthesis, involving fungi, bacteria, algae, yeast, or plant materials are more stable, efficient, cost-effective, and environmentally friendly. With rising global energy demand and a shift towards greener solutions, the focus has moved from hazardous chemical synthesis to green synthesis for CEOR. Although some research exists on green nanoparticles for oil recovery, a comprehensive review of these studies and the mechanisms (such as wettability alteration, interfacial tension reduction, and stability enhancement) is needed. This paper reviews recent advances in the biosynthesis of nanoparticles and nanocomposites for oil recovery, highlighting successful examples like SiO 2 /Montmorillonite/Xanthan and Fe 3 O 4 /SiO 2 /Xanthan, which improved recovery by altering wettability, reducing interfacial tension, and enhancing dispersion and thermal stability. The study also notes the preference for plant-based green synthesis over microbial synthesis due to complexity and cost. The findings provide insights into the impact of novel greenly synthesized nanoparticles in CEOR.