Geophysical monitoring of carbon dioxide (CO2) injections in a deep reservoir has become an important component of carbon capture and storage (CCS) projects. Until recently, the seismic method
was the dominant technique used for reservoir monitoring. In this paper we present a feasibility study of permanent electromagnetic (EM) monitoring of CO2 sequestration in deep reservoir using a novel borehole-to-surface EM (BSEM) method. The advantage of this method is that the sources of the EM field are located within the borehole close to the target reservoir, which increases the sensitivity and resolution of the method. Another innovation is the use of capacitive electric field sensors with an operational lifetime of tens of years. We illustrate the effectiveness of the BSEM method by computer simulating CO2 injection monitoring in the Kevin Dome sequestration site in Montana, USA.