| To improve reservoir characterization and groundwater monitoring, it is important to understand the influence of pore fluid chemistry on the induced polarization (IP) response of rocks. IP methods are effective because they are sensitive to electrochemical surface processes caused by the presence of clay particles or small amounts of contaminant that do not significantly alter the bulk resistivity of the pore fluid. However, the surface processes are also a function of the bulk pore fluid chemistry. To examine the role of bulk pore fluid chemistry on the IP response of rock, frequency-domain and time-domain IP measurement systems were built and calibrated. A series of experiments was performed to measure the IP response of Berea sandstone with varying pore fluid pH, ionic strength, and ion type. The experiments demonstrate the electrochemical complexity of earth materials and link common field IP parameters with geochemical parameters to improve non-invasive subsurface characterization. |
