Streaming Potential Measured for an Intact Rock Sample at Temperatures to 200 C

Abstract

Streaming potential was measured in an intact core sample of Inada granite, saturated with aqueous KCl solutions at three different concentrations, at temperatures between 50 and 200 C. We repeated the measurement at each concentration and succeeded in getting fairly reproducible results. The magnitude of the streaming potential coefficient decreases with increasing KCl concentration and increases with increasing temperature. Using a capillary model, we found that the magnitude of the zeta potential and the surface conductance (which dominates the sample conductivity) both increase with increasing temperature. As for the zeta potential, its magnitude is about one fourth of that measured for a crushed sample of Inada granite compared at ~50 C. This small magnitude can be explained by the presence of pores having very small hydraulic radius compared to the thickness of electrical double layer.