The effect of interfacial tension on hydrocarbon entrapment and mobilization near a dynamic water table

Abstract

Abstract The entrapment of residual hydrocarbon ganglia during water table fluctuations can produce a long‐term contamination threat to groundwater supplies that is difficult to remove. The mobilization of entrapped hydrocarbon ganglia depends on the balance between capillary and gravitational forces represented by the Bond number. The present work focuses on the influence of the interfacial tension between the hydrocarbon and the surrounding water on the entrapment and mobilization of the residual ganglia. Laboratory column tests using glass beads as the porous medium have been conducted to determine the residual saturation of a hydrocarbon (Soltrol 170) trapped during vertical displacements due to a rising water table and the necessary decrease in interfacial tension to mobilize these trapped ganglia. The interfacial tension was decreased by the addition of isopropyl alcohol to the water phase. Saturations of the three phases (water, hydrocarbon, and air) were measured with a dual‐beam y‐densitometer. T...