Can fluid-solid contact area quantify wettability during flow? – a parametric study

Wettability characterisation in a porous medium is challenging owing to the heterogeneity and large-scale of the interacting surface. Measuring the liquid-solid contact area can be used as a real-time wettability quantification at the Darcy scale. However, flow, grain size, and saturation path can affect the liquid-solid contact area. In this work, we use the two-tracer experiments to quantify the liquid-solid contact area and relate it with different parameters affecting the liquid-solid contact area. We do experiments at different conditions, i.e. (a) when the organic phase is at residual saturation and (b) when both phases flow. When the organic phase is immobile, increasing the flow rate does not change the residual saturation significantly; however, the water-solid contact area increases because of the increased corner flow. When both organic and aqueous phases flow, the relationship between the water saturation and water-solid contact area is found to be dependent on the grain size.