Electrical burst signature of pore-scale displacements

[1] Electric field bursts were passively observed when a nonwetting fluid displaced a wetting fluid in a porous material (drainage) as well as during imbibition experiments. A sandbox experiment was conducted to study these electrical disturbances using a network of very sensitive nonpolarizing electrodes located at the top surface of the tank. Drainage exhibited many more electrical bursts, with a higher magnitude, than imbibition. These events were only observed during drainage or imbibition, not prior to or after the water flowed inside the porous sandbox. We point out the possible relationship between the formation of Haines jumps and the occurrence of these electrical bursts. These bursts show a power law distribution during drainage with a power law exponent of about 1.7, in agreement with a previous published study using acoustic and hydroacoustic events. Imbibition does not display such a power law relationship.