High Resolution Reflection Seismic And Resistivity Imaging Of Deep Regional Aquifers For Stratigraphic Mapping

Chloride contamination has been detected in several deep regional aquifers in the Cold Lake,<br>Alberta area. Mapping these regional aquifers to determine their stratigraphy and their structural<br>relationships with the shallower overburden and the underlying bedrock has been the primary<br>focus of the geophysical investigations. Reflection seismic data were acquired to determine the<br>stratigraphy of the overburden and to identify possible pathways for contaminant migration. The<br>data suggest that glacial thrusting and differential loading, as well as fluvial features such as<br>channels have played a major part in controlling the stratigraphy in the area. To gain an<br>understanding of the hetrogeneties of the overburden, deep penetrating electrical resistivity<br>tomography (ERT) data were acquired. Hardware modifications were performed specifically for<br>this project in order to provide an increased depth of investigation. The ERT data suggests that<br>the overburden formations are heterogeneous over an order of tens of meters. Channel like<br>features were also imaged with the ERT. These results correlated well with both the seismic and<br>geophysical well logs, thus strengthening the overall geological interpretation. As a result of the<br>geophysical investigation, drilling targets have been identified, and hydrogeological models have<br>been refined, producing cost savings in the overall site characterization program.