The streaming potential of liquid carbon dioxide in Berea sandstone

Abstract

We report here, for the first time, evolution of the streaming potential coupling coefficient as liquid carbon dioxide infiltrates Berea sandstone. Using 125 Ω‐m tap water, the coupling coefficient determined before and after each CO2 flood of five samples averaged approximately −30 mV/0.1 MPa. After liquid CO2 passed through the specimens displacing all mobile pore water, trapped water remained and the coupling coefficient was approximately −3 mV/0.1 MPa. A bound water limit of the coupling coefficient for liquid CO2 flow was found using an air‐dried sample to be −0.02 mV/0.1 MPa. For initially water‐saturated samples, bulk resistivity varied during CO2 invasion from 330 Ω‐m, to 150 Ω‐m during CO2/water mixing, to a final value of 380 Ω‐m. Results suggest that trapped and bound water control electrical conduction and the electrokinetic response. Applications include monitoring CO2 injectate in subsurface reservoirs using the self potential method.