A COMPOSITIONAL SIMULATOR FOR MODELING SURFACTANT ENHANCED AQUIFER REMEDIATION .1. FORMULATION

We describe a three-dimensional, multicomponent, multiphase compositio nal finite-difference simulator for application to the analysis of con taminant transport and surfactant enhanced aquifer remediation (SEAR) of nonaqueous-phase liquid (NAPL) pollutants. Mixtures of surfactant, water and NAPL can form many types of micellar and microemulsion phase s with a complex and important dependence on many variables of which t he dilute aqueous solution typically assumed in SEAR models is just on e example. The phase behavior model is central to our approach and all ows for the full range of the commonly observed micellar and microemul sion behavior pertinent to SEAR. The other surfactant related properti es such as adsorption, interfacial tension, capillary pressure, capill ary number and microemulsion viscosity are all dependent on an accurat e phase behavior model. This has proven to be a highly successful appr oach for surfactant enhanced oil recovery modeling, so it was adapted to SEAR modeling. However, there are many significant differences betw een petroleum and environmental applications of surfactants, so many n ew features have been added to model contaminant transport and remedia tion and these are described and illustrated for the first time here.