Laboratory Monitoring of CO2 Migration and Phase Transition Using Complex Electrical Conductivity

We explore a new monitoring technique for the CO2 front propagation and phase transition processes using complex electrical conductivity measurements. A laboratory facility has been built to conduct core-flood experiments under reservoir conditions. CO2 is injected in both dry and brine-saturated reservoir rock. The objectives of the study are to evaluate and quantify the efficacy of complex electrical conductivity as a monitoring parameter for super-critical CO2 migration in the reservoir rock. Two injection experiments, targeting different injection scenarios, are carried out. In the first experiment, gaseous CO2 is injected into the core and subsequently the pressure and temperature conditions are gradually altered. The electrical response of the system is measured during the CO2 phase transition from gaseous to liquid and then to super-critical states. In the second experiment, the CO2 is injected into brine-saturated core while complex electrical conductivity is measured continuously. The experimental data can be adequately described by double Cole-Cole model. The experimental results show a high degree of repeatability and sensitivity. Our observations suggest that complex electrical measurements performed through borehole logging or cross-hole measurements can be useful for CO2 storage monitoring.