Laboratory evaluation of foams for mobility control and enhanced LNAPL recovery in heterogeneous sediment

Mélanie Longpré-Girard, Richard Martel, Thomas Robert, René Lefebvre, Jean-Marc Lauzon

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Contaminated Sites and Remediation II

ABSTRACT: Soil washing with surfactants has been proven to enhance LNAPL recovery in contaminated soils. However, in heterogeneous sediments, the injected fluids mainly flow in high permeability layers. Low permeability zones are therefore by-passed and remain untreated. A solution to this problem is foam injection. Foam, made by co-injection of air and surfactant solution blocks preferentially high permeability flow channels and divert flow through low permeability zones. The main objective of this study is to evaluate the efficiency of foam for the treatment of heterogeneous sediment contaminated with a LNAPL and containing low permeability layers. Several surfactant solutions were compared based on their toxicity and tested in laboratory to evaluate: (1) interfacial tension (IFT) reduction (pendant drop); (2) potential to dissolve LNAPL (batch test) and; (3) foamability and time needed for the foam to collapse (Ross Miles test). Most surfactant tested showed similar foamability but one did stand out with a IFT 20 times smaller than NAPL/water. This surfactant was therefore chosen for further testing. Several series of tests were run in 1D (sand column) on homogeneous silica sands. Also, surfactant sweep and displacement efficiencies were measured for both liquid and foam. The results from the 1D column tests will be used to design experiments in a 2D sand box model filled with layers of low and high permeability silica sands. These tests will allow the evaluation of the mobility control achieved by foam compared to liquid surfactant solutions.

Please include this code when submitting a data update: GEO2013_562

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