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<p>Surfactant-stabilized CO<sub>2</sub> foams reduce CO<sub>2</sub> mobility and improve CO<sub>2</sub> sweep efficiency during CO<sub>2</sub> enhanced oil recovery (EOR) and storage processes. However, the behavior of nonionic surfactant-stabilized CO<sub>2</sub> foams near their cloud-point regions remain under-documented at reservoir conditions. Cloud-point proximity impacts nonionic solubility and interfacial activity, which controls lamellae and foam strength at reservoir conditions. Foam generation and strength was evaluated in steady-state corefloods using Bentheimer sandstone at 180&#xa0;bar and 40&#xa0;°C and 60&#xa0;°C. A water-soluble nonionic alcohol-ethoxylate (Surfonic L24-22), at concentrations of 0.10 wt% and 1.0 wt%, were co-injected with supercritical CO<sub>2</sub>. Foam quality scans measured apparent foam viscosity (<i>µ</i><sub><i>app</i></sub>) as a function of gas fraction (<i>f</i><sub><i>g</i></sub>) whereas foam rate scans evaluated µ<sub>app</sub> as a function of injection velocity. With surfactant solution (0.10 wt%), strong foam with µ<sub>app</sub> = 125 cP and 81 cP was generated at 40&#xa0;°C and 60&#xa0;°C, respectively. Weaker foam at higher temperatures was related to faster film drainage from lower CO<sub>2</sub> density/viscosity and reduced interfacial activity near the cloud-point region. Increasing surfactant concentration generated stronger and more stable foams and shifted the optimal gas fraction (highest µ<sub>app</sub> ) from <i>f</i><sub><i>g</i></sub> = 0.80 (0.10 wt%) to <i>f</i><sub><i>g</i></sub> = 0.50 (1.0 wt%). Foam rate-scans at <i>f</i><sub><i>g</i></sub> = 0.70 exhibited shear-thinning behavior and apparent viscosity decreased by ~ 35% (40&#xa0;°C) and ~ 67% (60&#xa0;°C) between injection velocities of 16 and 4 ft/day. Overall, the results verify CO<sub>2</sub> mobility control by Surfonic L24-22 up to 60&#xa0;°C and isolate cloud-point proximity as a primary control of foam strength. The data set reported provides simulator-ready inputs for upscaling and optimizing CO<sub>2</sub>-foam EOR and storage processes, as improved CO<sub>2</sub>-foam parameters directly enhance model calibration and upscaling reliability.</p>

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Effect of temperature and surfactant concentration on CO2 foam strength in Bentheimer sandstone at reservoir conditions

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月26日

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  • Hilde Halsøy,
  • Arne Graue,
  • Zachary Paul Alcorn

摘要

Surfactant-stabilized CO2 foams reduce CO2 mobility and improve CO2 sweep efficiency during CO2 enhanced oil recovery (EOR) and storage processes. However, the behavior of nonionic surfactant-stabilized CO2 foams near their cloud-point regions remain under-documented at reservoir conditions. Cloud-point proximity impacts nonionic solubility and interfacial activity, which controls lamellae and foam strength at reservoir conditions. Foam generation and strength was evaluated in steady-state corefloods using Bentheimer sandstone at 180 bar and 40 °C and 60 °C. A water-soluble nonionic alcohol-ethoxylate (Surfonic L24-22), at concentrations of 0.10 wt% and 1.0 wt%, were co-injected with supercritical CO2. Foam quality scans measured apparent foam viscosity (µapp) as a function of gas fraction (fg) whereas foam rate scans evaluated µapp as a function of injection velocity. With surfactant solution (0.10 wt%), strong foam with µapp = 125 cP and 81 cP was generated at 40 °C and 60 °C, respectively. Weaker foam at higher temperatures was related to faster film drainage from lower CO2 density/viscosity and reduced interfacial activity near the cloud-point region. Increasing surfactant concentration generated stronger and more stable foams and shifted the optimal gas fraction (highest µapp ) from fg = 0.80 (0.10 wt%) to fg = 0.50 (1.0 wt%). Foam rate-scans at fg = 0.70 exhibited shear-thinning behavior and apparent viscosity decreased by ~ 35% (40 °C) and ~ 67% (60 °C) between injection velocities of 16 and 4 ft/day. Overall, the results verify CO2 mobility control by Surfonic L24-22 up to 60 °C and isolate cloud-point proximity as a primary control of foam strength. The data set reported provides simulator-ready inputs for upscaling and optimizing CO2-foam EOR and storage processes, as improved CO2-foam parameters directly enhance model calibration and upscaling reliability.