Electrical Signatures of Dual Domain Mass Transfer Observed in Rock Cores

Summary Dual domain mass transfer (DDMT), or the transfer of solute between mobile and less-mobile porosity domains, can cause anomalous breakthrough behavior observed during pumping operations. One novel method for characterizing DDMT is through geoelectrical inference, whereby electrical geophysical measurements are combined with pore fluid specific conductance measurements during a tracer experiment. Studies have shown the effectiveness of this method for characterizing DDMT in unconsolidated materials. We describe first of a kind instrumentation and results aimed at investigating evidence for a geoelectrical signature of DDMT in a rock core. A flow through apparatus was designed with the capability to simultaneously acquire bulk conductivity and specific conductance measurements on fluids extracted from the center of the core. A tracer experiment was run in three phases: initial, tracer flush, and tracer injection. Both specific conductance and bulk conductivity time series exhibit characteristic breakthrough behavior, with a delayed breakthrough of bulk conductivity relative to specific conductance, indicative of DDMT in the core. A strong hysteresis loop in the plot of bulk conductivity versus specific conductance is observed, consistent with the electrical geophysical signature of DDMT. The occurrence of DDMT at the core-scale indicates that it is likely ubiquitous within porous media across multiple scales.