Green-synthesized zinc quantum dots from Parsley leaves for enhanced oil recovery: Improving IFT, wettability, and oil recovery performance

Abstract
Nanotechnology has attracted significant attention in recent decades due to its diverse applications, particularly in chemical enhanced oil recovery (cEOR). By reducing fluid–fluid interfacial tension (IFT) and oil–rock contact angle (CA), nanomaterials offer a promising approach to improving oil recovery. This study explores the application of green-synthesized zinc quantum dots (Zn-QDs)—with an average size of approximately 10 nm and derived from parsley leaves—for EOR applications. The synthesized Zn-QDs were characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). Nanofluids were prepared by dispersing Zn-QDs in formation water and distilled water at concentrations ranging from 100 to 500 ppm. The stability and quality of the nanofluids were assessed by measuring key properties such as pH, density, and conductivity.\r\nExperimental evaluations, including IFT, CA, emulsion stability, and oil recovery tests, confirmed the effectiveness of these nanofluids. FW1-1-300 nanofluid, prepared by dispersing 300 ppm of nanodots in formation water, reduced the IFT significantly from 28.51 to 8.06 mN/m. Meanwhile, FW1:5-300 and FW1:15-400 were the most effective nanofluids for altering carbonate and sandstone wettability towards a strongly water-wet state, achieving CA values of 29.5° and 36°, respectively. Stability analysis indicated that lower concentrations of Zn-QDs provided better dispersion stability. In contrast, higher concentrations resulted in a significant reduction in droplet size, leading to the formation of a stable emulsion of crude oil and the injection solution. Ultimately, the green-synthesized nanodots enhanced the ultimate oil recovery by 22.28% of the original oil in place (OOIP) for carbonate rocks and 18.03% OOIP for sandstone rocks. These recovery rates represent a substantial improvement over the baseline water flooding recovery factors of 49.24% and 49.18% for carbonate and sandstone formations, respectively.

Author
Jagar A. Ali

DOI
https://doi.org/10.1016/j.petsci.2026.02.017

ISSN

Publish Date: 17-Feb-2026