Pore-Scale Study of Enhanced Mobilization of Residual NAPL Blobs in Porous Media by Seismic Waves

Applying seismic waves might improve the efficiency of conventional pump-and-treat technologies for cleaning up aquifers contaminated by nonaqueous phase liquids (NAPLs). The lack of a mechanistic understanding of the effects of seismic waves on the mobilization of residual NAPL blobs has prevented the method from being optimally applied. We investigate the hypothesis that the mobilization of trapped NAPL blobs can be enhanced by exploiting capillary-induced resonance. According to a theory that we developed, we setup physical experiments to image the response of trapped blobs to seismic waves in single pore channels and sphere packings at a high spatial and temporal resolution by using the optical refractive index-matching technique. The results show that capillary-induced resonance of trapped blobs occurs in single pore channels. Work is underway to show (1) that resonance also occurs for blobs in sphere packing and (2) that a blob can be optimally mobilized by excitation at its resonant frequency.