Laboratory Testing in Support of Surfactant-Alternating-Gas Foam Flood for NAPL Recovery from Shallow Subsurface

Use of viscosifiers have been shown helpful for mobility control when displacing higher viscosity fluids, and to improve sweep in heterogeneous media. Foam can be used as a viscosifier for this purpose. Selected surfactant solutions were investigated for their ability to generate foam within porous media and foam stability through batch and column experiments using field-obtained soil. The approach used to generate foam in-situ consisted of several cycles (7) of surfactant-alternating-gas originally developed to recover crude oil; 0.25 pore volumes (PV) surfactant followed by 0.25 PV of air. The apparent viscosity ranged from 60 to 100 cP from the 3rd to 7th cycle, respectively. Foam was collected from the column exit after being shut-in for 3 days as a proof of foam generation and stability. Results showed that the selected surfactant formulation can be used to generate foam in-situ for use in the field for environmental restoration.