Multiphase streaming potential in sandstones saturated with gas/brine and oil/brine during drainage and imbibition

We have measured the streaming potential in water-wet sandstones during both drainage and imbibition, and demonstrate that it behaves differently in oil/brine and gas/brine displacements. During drainage, the streaming potential remains significantly greater than zero at the irreducible water saturation in oil/brine displacements, but falls to zero in gas/brine displacements. During imbibition, the streaming potential at partial saturation in oil/brine displacements exceeds that measured at saturation, but not in gas/brine experiments. Our results have application to streaming potential measurements in the vadose zone, hydrocarbon reservoirs, contaminated aquifers and during CO₂ sequestration.