Capability of cross-hole electrical configurations for monitoring rapid plume migration experiments

•We evaluate the cross-hole resistivity configurations for real-time monitoring.•The anomaly detection and symmetry on the sensitivity pattern is analyzed.•An easy way to reduce acquisition time and amount of data for monitoring is presented.•This data reduction preserves the configurations capability and resolution.

Cross-hole electrical resistivity tomography is a useful tool in geotechnical, hydrogeological or fluid/gas plume migration studies. It allows better characterization of deep subsurface structures and monitoring of the involved processes. However, due to the large amount of possible four-electrode combinations between boreholes, the choice of the most efficient ones for rapid plume migration experiments (real-time monitoring), becomes a challenge. In this work, a numerical simulation to assess the capabilities and constraints of the most common cross-hole configurations for real-time monitoring is presented. Four-electrode configurations, sensitivity, dependence on the body location and amount of data were taken into account. The analysis of anomaly detection and the symmetry of the sensitivity pattern of cross-hole configurations allowed significant reduction of the amount of data and maintaining the maximum potential resolution of each configuration for real-time monitoring. The obtained results also highlighted the benefit of using the cross-hole AB–MN configuration (with both current – or potential – electrodes located in the same borehole) combined with other configurations with complementary sensitivity pattern.