Work

A novel numerical simulation method and applications of CO2 thickened flooding

Year: 2025

Type: article

Abstract: CO 2 -EOR (CO 2 Enhanced Oil Recovery) is currently one of the predominant techniques for improving oil recovery worldwide, offering significant production enhancement. However, during CO 2 flooding operations, challenges such as viscous fingering, gravity segregation, and reservoir heterogeneity often lead to severe gas channeling issues. Current mitigation strategies include water-alternating-gas (WAG) injection, CO 2 viscosity thickening, hydrogel plugging, foam blockage, and nanoparticle-based conformance control. Among these, CO 2 viscosity enhancement is considered a highly promising method for improving oil recovery. However, simulating CO 2 thickening has remained a significant challenge, with existing research primarily focused on laboratory experiments and limited numerical simulation studies. This study employs the CMG-GEM numerical simulation software, utilizing a modified typical heterogeneous “Egg Model” reservoir, to systematically investigate the mechanisms of CO 2 viscosity modification on recovery performance. To simulate CO 2 thickening, this paper proposes modifying the key viscosity parameter " $Vc$ (viscosity)” to approximate the CO 2 thickening process. A series of injection schemes were designed, including continuous gas injection, alternating injection of thickened and unthickened CO 2 , and water-alternating-gas (WAG) injection, to compare and evaluate the development performance under various conditions. The study systematically examines the effects of different thickening multiples, slug ratios, and reservoir heterogeneity levels. The results indicate that adjusting the viscosity parameter “ $Vc$ (viscosity)” can effectively simulate CO 2 thickening behavior. Furthermore, CO 2 viscosity enhancement demonstrates significant potential for improving oil recovery, providing both theoretical insights and practical guidance for numerical simulation studies of viscosity-modified CO 2 flooding.

Source: Scientific Reports

DOI: 10.1038/s41598-025-24132-2