CO2 Field Laboratory at Svelvik Ridge (Norway). Electrical Resistivity and Sonic Monitoring during CO2 Shallow Injection

The CO2FieldLab shallow injection experiment is a mutual effort from several research groups and organizations (SINTEF, NGI, BRGM, BGS, CNRS, imaGeau and Schlumberger). The objective is to create a downhole leakage of CO2 in order to determine sensitivity of CO2 monitoring systems with respect to CO2 distribution and leakage detection. The CO2 displacement in the subsurface and at the surface was monitored with an exhaustive set of techniques. For this, the field Laboratory for monitoring CO2 migration and leakage was established in glacial deposit that forms Svelvik ridge, 50 km south of Oslo. The shallow injection experiment was conducted in fall 2011 with a monitoring plan designed to spatially and temporally monitor the expected plume development. The monitoring equipment was distributed around the 20m deep injection point of an inclined well. An integrated set of surface and downhole strategies was deployed across a 64m2 square monitoring area. The data recorded by CNRS are presented here. The CNRS techniques included: permanent downhole electrical resistivity observatory, time-lapse downhole induction and sonic logging. The CO2 plume was successfully detected and characterized by these methods even if the trajectory of migrating CO2 deviated from the monitoring predictions.