Imaging and modeling of flow in porous media using clinical nuclear emission tomography systems and computational fluid dynamics

Abstract

This paper presents experimental and modeling aspects of applying nuclear emission tomography to study fluid flow in laboratory packed porous media columns of the type frequently used in geophysics, geochemistry and hydrology research. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are used as non-invasive tools to obtain dynamic 3D images of radioactive tracer concentrations. Dynamic sequences obtained using 18F-FDG PET are used to trace flow through a 5 cm diameter × 20 cm tall sand packed column with and without an impermeable obstacle. In addition, a custom-made rotating column setup placed in a clinical two-headed SPECT camera is used to image 99mTc-DTPA tracer propagation in a through-flowing column (10 cm diameter × 30 cm tall) packed with recovered aquifer sediments. A computational fluid dynamics software package FLUENT is used to model the observed flow dynamics. Tracer distributions obtained in the simulations in the smaller column uniformly packed with sand and in the column with an obstacle are remarkably similar to the reconstructed images in the PET experiments. SPECT results demonstrate strongly non-uniform flow patterns for the larger column slurry-packed with sub-surface sediment and slow upward flow. In the numerical simulation of the SPECT study, two symmetric channels with increased permeability are prescribed along the column walls, which result in the emergence of two well-defined preferential flow paths. Methods and results of this work provide new opportunities in hydrologic and biogeochemical research. The primary target application for developed technologies is non-destructive, non-perturbing, quantitative imaging of flow dynamics within laboratory scale porous media systems.

Quantifying solute spreading and mixing in reservoir rocks using 3-D PET imaging

“…This approach was followed in this study, where we have applied [11C]PET for the dynamic imaging of miscible displacements in a Berea sandstone core. While the use of this technique to image flows in porous media has been reported previously (Khalili et al 1998;Gründig et al 2007;Boutchko et al 2012;Fernø et al 2015), the novelty of this work is its application to the study of hydrodynamic dispersion in rocks. The strength of the analysis lies in the approach that contains a significant deterministic component, because an independently measured 3-D permeability map of the sample is used to identify convective pathways and to build a streamtube model.…”

“…With relevance to the present work, PET has been used to study the porosity of rock samples (Degueldre et al 1996;Maguire et al 1997) and to image transport in sediments (Khalili, Basu & Pietrzyk 1998) and sandstones (Ogilvie, Orribo & Glover 2001). However, with the avowed intention of demonstrating the potential of PET to visualize fluid pathways inside porous samples, most studies so far have been largely qualitative, and the use of this technique for quantitative analyses is just beginning (Gründig et al 2007;Boutchko et al 2012;Fernø et al 2015).…”

Links between soil properties and steady‐state solute transport through cultivated topsoil at the field scale

“…Meanwhile, it is possible to create detailed 3‐D images pore spaces of undisturbed soil by means of X‐ray tomography, providing resolutions in the micrometer scale [e.g., Schlueter et al ., ; Wang et al ., ]. With the help of X‐ray tomography and similar noninvasive methods as neutron beam scattering [e.g., Carminati et al ., ] or positron emission tomography [e.g., Boutchko et al ., ], it is to expect that relationships between the soil pore‐network geometry and the water flow and solute transport will be quantifiable within the near future. However, high‐resolution imaging methods like X‐ray tomography are to our knowledge restricted to sample sizes of a few decimeters and are presently not applicable in the field.…”

Geoscientific process monitoring with positron emission tomography (GeoPET)

“…PET is least affected by material interferences. Boutchko et al (2012) presented applications of both tomographic nuclear imaging modalities.…”

“…Numerous investigations of flow processes in various rock formations have been conducted since 1989 (van den Bergen, 1989;Benton and Parker, 1996;Khalili et al, 1998;Degueldre et al, 1996;Ogilvie et al, 2001;Tenchine and Gouze, 2005;Goethals et al, 2009;Kinsella et al, 2012;Boutchko et al, 2012;Fernø et al, 2015;Gauteplas, 2015;Hoff et al, 1996).…”