National Ground Water Association

2014 Darcy Lecture

Dorthe Wildenschild, Ph.D., is an associate professor in the School of Chemical, Biological and Environmental Engineering at Oregon State University. Research in her group focuses on physics, chemistry, and microbiology of relevance to flow and transport in porous media. Much of her work is supported by high resolution imaging and applications primarily involve subsurface multiphase flow phenomena. 

Choice of two lectures

What Happens in the Pore, No Longer Stays in the Pore: Opportunities and Limitations for Porous Media Characterization and Process Quantification Using X-ray Tomography

Gain insight on how x-ray tomography has advanced to the point where it is possible to probe porous media in great detail, allowing for fully quantitative analyses of processes and mechanisms at the pore scale. Detail resolution ranges from hundreds of microns for cm-sized samples down to hundreds of nm for micron-sized objects. Contrast depends on density and atomic number of the imaged object, and creative use of contrast agents can help delineate otherwise difficult-to-identify features.

Also discussed will be technique limitations, as well as new potential advances that will allow for exciting new research in coming years. Applications of the technique to remediation of non-aqueous phase liquid in groundwater, the fundamentals of multiphase flow, and geologic sequestration of carbon dioxide will be presented.

Optimizing Capillary Trapping as a Carbon Dioxide Mitigation Strategy: Pore-Scale Findings in Support of Larger-Scale Implementation

Discover how x-ray microtomography is being studied for possible use as a technique to optimize capillary trapping of carbon dioxide in this presentation. Capillary trapping is a
mechanism supporting carbon capture and storage (CCS), which is being considered as a mitigation strategy for emissions from concentrated sources such as coal-fired power plants.

CCS relies on geologic sequestration of captured carbon dioxide. Of concern in this process is the leakage of carbon dioxide back to the atmosphere, either acute or slower longterm escape, as well as related acidification of groundwater resources along the migration path.

Initial work using x-ray microtomography has focused on proxy fluid-based systems and experiments carried out at ambient conditions. As the interfacial tension, viscosity, and carbon
dioxide injection (as well as subsequent brine flood injection) rates are varied, trends have been observed with the type of porous medium (unconsolidated vs. consolidated), varying wetting and nonwetting phase viscosity, and flow rates. The latter in particular has been investigated for its effect on morphology and connectivity of the trapped nonwetting phase (i.e., the supercritical carbon dioxide).

Results so far indicate that carbon dioxide injection can be manipulated to facilitate optimal trapping of residual carbon dioxide, both in terms of amount and with respect to size/ connectivity characteristics that may favorably support subsequent trapping reactions (e.g., dissolution and mineral formation).

Continuing education points

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