The effect of double layer overlap on measured streaming currents for toluene flowing through sandstone cores

Streaming current measurements have been made on toluene flowing through sa ndstone rock cores, whose pore size was estimated by mercury porosimetry. T he streaming current method, though requiring pico-amp measurements, was pr eferred over streaming potential as the latter is subject to surface conduc tivity errors. Having estimated pore area/length ratios an (apparent) elect rokinetic potential was obtained which, as expected, increased numerically with pore size as a result of double layer overlap effects. After a measure ment using a I mm internal diameter silica capillary, to represent effectiv e infinite pore size, the data were fitted to a theoretical expression for double layer overlap in slit-like pores. (C) 2001 Published by Elsevier Sci ence BN.