Laboratory monitoring of CO_2 migration within brine-saturated reservoir rock though complex electrical impedance

摘要

We investigate the ability of complex electrical measurements to monitor the CO_2 front propagation within brine-saturated reservoir rock. A laboratory facility has been developed to perform CO_2-brine substitution experiments under reservoir conditions. In the present study, CO_2 is injected into a brine-saturated core while the complex electrical impedance is measured continuously using an array of four electrode pairs. Both magnitude and phase of the electrical impedance reveal the sensitivity to the injected fluid. We find that recent adaptations of the Cole-Cole model can explain quite well the observed variation of complex electrical impedance as a function of CO_2-brine saturation. This suggests the potential utility of complex electrical impedance measurements in an efficient CO_2-storage monitoring program.