Abstract The controlled-source electromagnetic (CSEM) method is a proven and promising geophysical technique in the hydrocarbon exploration area. Recently, there is increasing interest in applying it to CO2-injection monitoring in both land and marine environments. For example, a marine CSEM survey has been carried out in the Sleipner area in 2008 to map the CO2 plume in the Utsira formation. There are still scientific and technical issues to resolve and improve further. In the current study, we focus on two particular issues. The first is to explore the possibility of modeling the CO2 plume in the Utsira formation at the Sleipner area by means of an effective anisotropic resistivity layer. The second is the application of so-called surface-to-borehole CSEM in order to increase the sensitivity of CSEM data to the CO2 plume.