Lawrence Berkeley National Laboratory

Electromagnetic (EM) geophysical techniques offer the possibility of monitoring subsurface CO2 in saline reservoirs due to the fact that CO2 has high electrical resistivity compared to the surrounding geologic materials. In this paper we first discuss the underlying physics of two different borehole-based EM monitoring techniques; electrical resistivity tomography (ERT) and crosswell EM. This discussion is followed by the description of an experiment at the Carbon Management Canada CaMI FRS test site where time-lapse single well ERT and crosswell EM data have been acquired to image CO2 injection into a shallow aquifer. Resistivity imaging results from inversion of the two data types separately and jointly will be compared and contrasted, and interpretation of the extent of the injected CO2 provided.