Wettability effects on the natural remobilization of mixed DNAPL pools

Although commonly considered immobile, certain multicomponent DNAPL pools may remobilize simply through compositional changes caused by the preferential dissolution of components of higher solubility. This process, termed natural remobilization, was previously demonstrated for open pools and pools within porous media in a 2-dimensional flow cell. The potential for remobilization is controlled by the capillary pressure at the pool boundaries and the displacement pressure of the capillary barrier. These parameters will be affected by the change in fluid properties (primarily density) and the loss of pool height occurring during dissolution, as well as hysteretic and wettability effects. Using these two sets of experiments and an additional visualization within a glass capillary, it was determined that enhanced contact-angle hysteresis, associated with a change in wettability reduces the potential for natural remobilization for certain pools within porous media. However, it increases the potential for remobilization for open pools.