HR: 16:30h
AN: H12K-03    [PDF]
TI: Changes in Wetting Hysteresis During Bioremediation: Changes in fluid flow behavior monitored with low-frequency seismic attenuation
AU: * Wempe, W
EM: wempe@cires.colorado.edu
AF: CIRES, University of Colorado CIRES Bldg, Box 216, Boulder, CO 80309-0216 United States
AU: Spetzler, H
EM: spetzler@cires.colorado.edu
AF: CIRES, University of Colorado CIRES Bldg, Box 216, Boulder, CO 80309-0216 United States
AU: Spetzler, H
EM: spetzler@cires.colorado.edu
AF: Geology Department, University of Colorado Box 399, Boulder, CO 80309-0399 United States
AU: Kittleson, C
EM: christine.kittleson@colorado.edu
AF: CIRES, University of Colorado CIRES Bldg, Box 216, Boulder, CO 80309-0216 United States
AU: Pursley, J
EM: jill.pursley@colorado.edu
AF: Geology Department, University of Colorado Box 399, Boulder, CO 80309-0399 United States
AB: We observed significant reduction in wetting hysteresis with time while a diesel-contaminated quartz crystal was dipped in and out of an oil-reducing bacteria solution. This wetting hysteresis is significantly greater than the wetting hysteresis when the diesel-contaminated quartz crystal is dipped in and out of (1) water, (2) diesel and (3) the bacterial food solution that does not contain bacteria. The reduction in wetting hysteresis of the bacteria solution on the quartz surface results from a reduction in the advancing contact angle formed at the air-liquid-quartz contact with time; the receding contact angle remains the same with time. Our results suggest that the bacteria solution moves across the quartz surface with less resistance after bioremediation has begun. These results imply that bioremediation may influence fluid flow behavior with time. For many fluid-solid systems there is a difference between the contact angle while a contact line advances and recedes across a solid surface; this difference is known as wetting hysteresis. Changes in wetting hysteresis can occur from changes in surface tension or the surface topography. Low contact angle values indicate that the liquid spreads or wets well, while high values indicate poor wetting or non-wetting. Contact angles are estimated in the lab by measuring the weight of the meniscus formed at the air-liquid-quartz interface and by knowing the fluid surface tension. In the lab, we have been able to use low-frequency seismic attenuation data to detect changes in the wetting characteristics of glass plates and of Berea sandstone. The accepted seismic attenuation mechanism is related to the loss of seismic energy due to the hysteresis of meniscus movement (wetting hysteresis) when a pore containing two fluids is stressed at very low frequencies ($<$ 10 Hz). When fluid-fluid-solid systems that exhibit wettability hysteresis are stressed at low frequencies, we observe seismic attenuation, whereas in a system that does not exhibit wettability hysteresis we do not. From our wettability hysteresis results, we conclude that we may be able to monitor bioremediation progress using seismic attenuation data. We are measuring low-frequency seismic attenuation in the lab while flowing bacteria solution through Berea sandstone and we are testing this application in the field.
DE: 0400 Biogeosciences
DE: 0935 Seismic methods (3025)
DE: 1829 Groundwater hydrology
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting