Measuring electric resistivity of rock specimens injected with gas, liquid and supercritical CO²

CO₂ sequestration in a deep aquifer is considered one of the most effective method to solve Global warming. We must understand the behavior of injected CO₂ to confirm long-term stability and economic efficiency of CO₂ sequestration. We tried to monitor the behavior of gas, liquid and supercritical CO₂ injected into water-saturated sandstone by measuring the resistivity of rock specimens. CO₂ of gas, liquid, and supercritical phases was flushed through the sandstone specimens at three different flow rates. We could monitor the time-lapse behavior of CO₂ in water-saturated sandstones. Also, we tried to convert the resistivity data to the CO₂ saturation using Archie's equation. The saturations estimated from resistivity becomes nearly equal to the values calculated from actual outflow volumes. This result indicates the high reliability of electric exploration to monitor CO₂ saturation.