The investigation of CO2-brine displacement in porous rock is important to predict plume migration and initial pore-space utilization in CO2 storage. The measurement of relative permeability saturation functions (kr(Sw)) characterizing displacement requires relatively homogeneous core material. Carbonates, however, are often heterogeneous on various length scales. While microscopic heterogeneity determines kr(Sw), larger-scale heterogeneity that is not statistically represented in the measured volume affects the investigation. In this paper we present CO2-brine unsteady-state core flood experiments in order to characterize CO2-brine primary drainage in Estaillades limestone. We describe the experiments by means of numerical simulations assuming 1-D homogeneous rock and parameterized kr(Sw) relationships. Assisted history matching methodologies were used to find the kr(Sw) parameters which minimize a mismatch function, giving the best match to the experimental data. The effects of larger-scale heterogeneity are still not taken explicitly into account (just by sample selection) and are a subject for further discussion.
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