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<p>CO<sub>2</sub>-EOR (CO<sub>2</sub> Enhanced Oil Recovery) is currently one of the predominant techniques for improving oil recovery worldwide, offering significant production enhancement. However, during CO<sub>2</sub> 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<sub>2</sub> viscosity thickening, hydrogel plugging, foam blockage, and nanoparticle-based conformance control. Among these, CO<sub>2</sub> viscosity enhancement is considered a highly promising method for improving oil recovery. However, simulating CO<sub>2</sub> 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<sub>2</sub> viscosity modification on recovery performance. To simulate CO<sub>2</sub> thickening, this paper proposes modifying the key viscosity parameter "<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(Vc\)</EquationSource> </InlineEquation>(viscosity)” to approximate the CO<sub>2</sub> thickening process. A series of injection schemes were designed, including continuous gas injection, alternating injection of thickened and unthickened CO<sub>2</sub>, 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 “<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(Vc\)</EquationSource> </InlineEquation>(viscosity)” can effectively simulate CO<sub>2</sub> thickening behavior. Furthermore, CO<sub>2</sub> viscosity enhancement demonstrates significant potential for improving oil recovery, providing both theoretical insights and practical guidance for numerical simulation studies of viscosity-modified CO<sub>2</sub> flooding.</p>

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A novel numerical simulation method and applications of CO2 thickened flooding

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月6日

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  • Ming Gao,
  • Wenfeng Lv,
  • Wei Wang,
  • Wanlu Liu,
  • Ji Qi,
  • Lu Zou,
  • Zhenzhen Dong,
  • Weirong Li

摘要

CO2-EOR (CO2 Enhanced Oil Recovery) is currently one of the predominant techniques for improving oil recovery worldwide, offering significant production enhancement. However, during CO2 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, CO2 viscosity thickening, hydrogel plugging, foam blockage, and nanoparticle-based conformance control. Among these, CO2 viscosity enhancement is considered a highly promising method for improving oil recovery. However, simulating CO2 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 CO2 viscosity modification on recovery performance. To simulate CO2 thickening, this paper proposes modifying the key viscosity parameter " \(Vc\) (viscosity)” to approximate the CO2 thickening process. A series of injection schemes were designed, including continuous gas injection, alternating injection of thickened and unthickened CO2, 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 CO2 thickening behavior. Furthermore, CO2 viscosity enhancement demonstrates significant potential for improving oil recovery, providing both theoretical insights and practical guidance for numerical simulation studies of viscosity-modified CO2 flooding.