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

BONGIOVANNI M. V.; GRÜNHUT V.; LÓPEZ E.

Bordeaux

Conferencia; Near Surface Geoscience'21; 2021

Europan Asociation of Geoscience and Engineering

Surfaceelectrical 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 heavilyinfluenced 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 toextend the anomaly detection capability beyond the limits of surface electricsurveying. Even more, with two wells, the cross-hole DC electrical surveyingprovides detailed information on the variation of electrical resistivitybetween the boreholes, but just in a very limited zone near them. Theimplementation of borehole to surface electrical resistivity tomography allowsto reduce this limitation. Such an arrangement is expected to provide anincrease in detection capability in the area in-between the boreholes andsurface. In the present work we studied the feasibility of surface-downhole ERTmeasurements in order to detect and estimate the dimensions of a contaminationplume in a deep aquifer that lies above an oil reservoir, performing a physicalmodel at laboratory scale. We conclude that the detection and consequently themonitoring of contaminated deep aquifers with two wells using surface-downholeERT is possible.