| Title | Field Experiments to Characterize Hydrological Properties of Fractured Rock Using Continuous Borehole Self-Potential Measurement |
|---|---|
| Authors | Nishi, Yuji; Ishido, Tsuneo; Negi, Tateyuki |
| Year | 2006 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Power Plants; self-potential, borehole SP monitoring, fracture, Kamishi Mine, numerical simulation |
| Abstract | Numerical simulation studies by Ishido and Pritchett (2003) showed that borehole SP monitoring has a great deal of promise for complementing pressure transient data to help map and characterize fracture networks. In order to study this prediction experimentally, we have carried out continuous SP monitoring using multi Ag-AgCl electrodes installed within well KF-1 at the Kamaishi Mine, Japan. The observed streaming potential divided by the pressure change due to opening wellhead valve increases with increasing interval of valve opening from 30 seconds to 5 minutes and almost constant between 5 and 100 minutes, which suggests that the time required for pressure equilibrium between the fracture and matrix regions is around 5 minutes for the surrounding granodiorite body. |