Time-lapse Electrical Resistivity Monitoring of Subsurface CO2 Storage at the Maguelone Experimental Site (France)

CO2 geological storage remains a recent research field and many questions are still open, particularly for saline formations, which are expected to provide over time a larger storage capacity than depleted hydrocarbon reservoirs. The Maguelone shallow experimental site for shallow CO2 injection (Mediterranean coastline, Gulf of Lions, France) has been developed to study in an integrated manner surface and in-situ (downhole) monitoring methods. The presence of two small reservoirs with impermeable boundaries (R1: 13-16 m and R2: 8-9 m) provides an opportunity to study a saline formation for gas geological storage both in the field and in a laboratory context. During the shallow injection experiment (~48 m3 of CO2 was injected over ~2 hours on December 4, 2014), traces of the CO2 plume were detected by time-lapse downhole and surface electrical resistivity monitoring techniques, although some of the injected CO2 appeared to leak along the new injection hole, which should be corrected in the future with additional cementing around the new holes.