A physical model to study deep contaminated sites: ERT study with surface-downhole electrode configuration.

M.V. BONGIOVANNI; GRUNHUT DUENYAS VIVIAN; LÓPEZ ERNESTO

Congreso; NSG2021 27th European Meeting of Environmental and Engineering Geophysics; 2021

Surface electrical resistivity tomography (ERT) is a widely used tool to map the subsurface. One of its limitations is the decrease in resolution as depth increases. Another limitation is that the electrodes planted on the surface can be heavily influenced by temperature, weather, and water saturation changes over time. Consequently, the data can be easily contaminated by noise and, therefore, unreliable for long term monitoring. Borehole DC electrical surveying allows to extend the anomaly detection capability beyond the limits of surface electric surveying. Even more, with two wells, the cross-hole DC electrical surveying provides detailed information on the variation of electrical resistivity between the boreholes, but just in a very limited zone near them. The implementation of borehole to surface electrical resistivity tomography allows to reduce this limitation. Such an arrangement is expected to provide an increase in detection capability in the area in-between the boreholes and surface. In the present work we studied the feasibility of surface-downhole ERT measurements in order to detect and estimate the dimensions of a contamination plume in a deep aquifer that lies above an oil reservoir, performing a physical model at laboratory scale. We conclude that the detection and consequently the monitoring of contaminated deep aquifers with two wells using surface-downhole ERT is possible.