Streaming potential response during pumping in a fractured rock aquifer
Abstract
When water flows through a geologic medium in the subsurface, an electric field is generated in the flow field due to direct electrokinetic coupling attributed to existence of the electric double layer (EDL) at the rock-water interface. The electric potentials, referred to as streaming potentials (SP), associated with such an electric field can be measured and used to characterize the groundwater flow-field. Although there have been several attempts to quantify aquifer properties such as transmissivity and storativity using responses of SP to pumping of groundwater, the correlation between SP and in situ groundwater flow in fractured rock has not been investigated thoroughly. To quantify their correlation, nine vertical boreholes with 10 m length were radially installed in an underground tunnel whose host rock is fractured granite. Geophysical logging such as acoustic televiewing and hydraulic testing were conducted to characterize the hydrogeologic properties of the host rock at the test boreholes. Electrodes were installed in each borehole and SP responses were observed with the electrodes during pumping at the central borehole in the test borehole nest. Results show that a small-scale permeable fracture zone with a transmissivity of ~ m2/s crosses five boreholes including the pumping borehole. The SP response at each borehole indicates connectivity between the fracture zone and boreholes well.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.H33D1359J
- Keywords:
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- 1829 HYDROLOGY / Groundwater hydrology;
- 1835 HYDROLOGY / Hydrogeophysics