Applicability of surface-to-borehole EM to CO₂ storage monitoring in the North Sea setting

We present potential advantages of offshore surface-to-borehole EM acquisition for CO₂ storage monitoring by comparing with conventional surface-to-surface EM acquisition. A sensitivity study is done with a simple geological model built for various plume sizes and various CO₂ saturations at a reservoir located about 2700m below the seabed. The resulting responses at receiver dipoles in the well suggest high sensitivity for both vertical and horizontal dipole sources towed above seabed. It is also shown that the survey layout of the surface-to-borehole EM could be much smaller than that of the surface-to-surface i.e. short Tx-Rx offsets.