SIMULATION ON THE SURFACTANT-POLYMER FLUSHING OF HETEROGENEOUS AQUIFERS CONTAMINATED WITH NONAQUEOUS PHASE LIQUIDS

A three-dimensional, multiphase, multicomponent compositional simulator is employed to simulate the NAPL migration and groundwater flow and transport in spatially correlated heterogeneous fields during surfactant-polymer flushing. Spatial distributions of saturations in the NAPL and temporal changes of organic recovery, effluent concentrations of organics and surfactant, and pressure drop at the injection well were compared with those in homogeneous aquifer and related to heterogeneity. Variations in permeability fields have a pronounced effect on the organic recovery efficiency due to the long-term persistence of nonaqueous phase liquid in low permeability regions and additional dispersion caused by the randomly heterogeneous aquifer. Results of simulations illustrate associated tailing of effluent organic concentrations at the production well. Permeability heterogeneity also increases the injection pressure drop and results in significant loss in injectivity over the remediation life. For a small slug, surfactant-enhanced remediation had a relatively small improvement on the recovery of NAPL, especially in highly heterogeneous aquifers. The tendency of the high concentration organic plumes to migrate to the other layer by gravity forces and crossflow is also demonstrated and is shown to enhance remediation of aqueous phase organic.