A novel approach for wettability estimation in geological systems by fluid-solid interfacial area measurement using tracers

Wettability plays a vital role in many applications of flow in porous media and affects Darcy scale flow parameters by influencing the fluid-solid interfacial area. Therefore, quantifying the fluid-solid interfacial area can provide a way to measure wettability at the Darcy scale. Here, we experimentally explore a dual-tracer method, which can also be scaled to large geological reservoirs to quantify the fluid-solid interfacial area during the multiphase flow through a porous medium for different wetting conditions. Using our experiments, we demonstrate the influence of different saturations, wettability and flow conditions on the solid-liquid interfacial area. When oil is in the residual phase, we observe that the solid-water interfacial area increases with the increase in water saturation for the water-wet and mixed-wet cases. However, the water-solid interfacial area decreases with an increase in water saturation for the oil-wet case. We increase the water saturation by increasing the water flow rate; therefore, the anomalous behaviour seen in the oil-wet case can be attributed to the rearrangement of oil and water at higher water flow rates. When both oil and water are flowing, the solid-water interfacial area increases with water saturation for all the wettability cases and increases in water wettability as anticipated. Synopsis: Wettability measurements at Darcy-scale give a broad idea of overall subsurface wetting conditions for application in CO2 sequestration, ground-water remediation or oil recovery.

Automated summary

Wettability is a key factor in flow through porous media, affecting Darcy-scale flow parameters by influencing fluid-solid interfacial area. Quantifying this area provides a way to measure wettability. Experimental results show that different saturations, wettability, and flow conditions have an impact on solid-liquid interfacial area. Oil as the residual phase leads to an increase in solid-water interfacial area with increasing water saturation for water-wet and mixed-wet cases, but a decrease for oil-wet case.