Jennifer R. Brown, PhD, Montana State University (Bozeman)
This purpose of this research is to study non-Newtonian fluid dynamics, specifically of polymer and micelle solutions, in porous media with Magnetic Resonance (MR). This has relevance to enhanced oil recovery. MR techniques have the ability to measure, non-invasively and without the use of a tracer, transport dynamics in opaque porous media. Here, pulsed gradient spin echo (PGSE) techniques are being used to directly measure the probabilities of displacement and therefore anomalous diffusive dynamics as well as diffusion and dispersion in any direction. To date, significant progress has been made and a publication is in preparation.
An example of gathered data is shown in propagator measurements of water flowing in a model bead pack of 241 mm diameter polystyrene beads (Figure 1a) demonstrate the evolution from short observation times (50 ms) where displacements are centered around zero to Gaussian statistics at long observation times (300 ms). In Figure 1b, however, a micellar solution of 10 mM cetyl trimethylammonium p-toluene sulfonate (CTAT) in water shows non-Gaussian dynamics even at long observation times, including a peak at zero displacement and a long tail at higher displacements. CTAT exhibits shear-thickening at 10 mM concentration and these preliminary measurements demonstrate that the shear-thickening material properties of the micellar solution impact the velocity field and hydrodynamic dispersion within a porous media.
Figure 1. Averaged propagators for a model porous media system (dp= 241 mm, D= 6 mm). (a) Water at 400ml/hr at observation times of 50 ms (line) and 300 ms (dashed line). (b) 10 mM CTAT at 400 ml/hr at observation times of 50 ms (line) and 300 ms (dashed line).
This research has enabled the PI to fund a graduate student who is anticipated to earn his MS in Chemical Engineering by summer 2014. With this project, the PI has also obtained significant preliminary data suitable for application for ongoing funding and the funding has had a high level of impact on the PI's early career in preparation for tenure.