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2017 Nov 1 - Dec 21
2018 Feb 7 - Apr 3
2018 Proposal/BTR deadline: 12/1/17
2018 Apr 11 - Jun 4
2018 Proposal/BTR deadline: 2/1/18
C.J. G.Darnault, D.A. DiCarlo1, T.W.J.Bauters, J.A.
Throop, T.S. Steenhuis, J.-Y. Parlange and C.D. Montemagno
Department of Agriculture and Biological Engineering, Cornell University
1Department of Petroleum Engineering, Stanford University
Accurate monitoring of flow instabilities, which can occur when water
displaces non-aqueous phase liquids (NAPLs, eg. oil) in porous media, is
an important component of predicting the transport and fate of these
compounds in the subsurface. In particular, flow situations in which
three separate phases (such as water, NAPL, and air) exist in the porous
media have only begun to be studied. Unfortunately, very few methods
exist that allow fast and accurate determination of fluid contents in
three phase transient flow fields.
This group has developed two techniques to attack this problem: a light
transmission technique and a dual-energy x-ray technique. The x-ray
technique uses synchrotron x-rays from CHESS to measure three-phase
fluid concentrations on the time scale of seconds. Using the harmonic
content of x-ray diffraction from perfect silicon crystals, they obtain
a high intensity x-ray beam consisting of two distinct tunable energies,
typically 20 keV and 40 keV. Scintillation detectors installed before
and after the sample chamber measured incident and transmitted
intensities of both x-ray energies. Simple configurations of oil
infiltrating into wetted soil were unstable at low flow rates and
produced fingers. The widths and concentrations within each finger
depended on the concentration of the other phase. When combined with the
light transmission and simultaneous pressure measurements, a complete
picture of three-phase flow instabilities can be realized.
A report of this work won an "Outstanding Student Paper" award for Ph.D.
candidate T. W. J. Bauters from the American Geophysical Union Hydrology
Section.
Transmission light images through translucent
silica sand media showing the equilibrium concentration of oil,
water and air in different layers. Visual image (left), hue image
(center) and intensity image (right) are shown. X-ray data on this
cell were used to calibrate the absolute densities of each
component.