Dynamic wettability alteration in immiscible two-phase flow in porous media: Effect on transport properties and critical slowing down

Abstract

The change in contact angles due to the injection of low salinity water or any other wettability altering agent in an oil-rich porous medium is modeled by a network model of disordered pores transporting two immiscible fluids. We introduce a dynamic wettability altering mechanism, where the time dependent wetting property of each pore is determined by the cumulative flow of water through it. Simulations are performed to reach steady-state for different possible alterations in the wetting angle ($\theta$). We find that deviation from oil-wet conditions re-mobilizes the stuck clusters and increases the oil fractional flow. However, the rate of increase in the fractional flow depends strongly on $\theta$ and as $\theta\to 90^\circ$, a critical angle, the system shows critical slowing down which is characterized by two dynamic critical exponents.Comment: 8 pages, 9 figure