Pore-Scale Characterization of Organic Immiscible-Liquid Morphology in Natural Porous Media Using Synchrotron X-ray Microtomography

Abstract

The objective of this study was to quantitatively characterize the pore-scale morphology of organic immiscible liquid residing within natural porous media. Synchrotron X-ray microtomography was used to obtain high-resolution, three-dimensional images of solid and liquid phases in packed columns. The image data were processed to generate quantitative measurements of organic-liquid blob morphology. Three porous media, comprising a range of particle-size distributions, were used to evaluate the impact of porous-medium texture on blob morphology. The sizes and shapes of the organic-liquid blobs varied greatly, ranging from small spherical singlets (> or = 0.03 mm in diameter) to large, amorphous ganglia with mean lengths of 4-5 mm. The smaller blobs were composed primarily of singlets, which comprised approximately half of all blobs for all three media. Conversely, large, complex blobs comprising four or more bodies composed 11-24% of the total number of blobs. However, the majority of the total organic-liquid surface area and volume was associated with the largest blobs. The ratio of median blob size to median grain size was close to unity for all three systems. The distribution of blob sizes was greatest for the porous medium with the broadest particle-size and pore-size distributions. These results illustrate the utility of synchrotron X-ray microtomography for characterizing fluid distributions at the pore scale in natural porous media.

Metric Identification and Protocol Development for Characterizing DNAPL Source Zone Architecture and Associated Plume Response

“…All of these models assume that transport occurs only in the aqueous phase, with an immobile TCE-DNAPL, distributed uniformly as spherical singlets. This assumption is supported by visualization of DNAPL distributions within similar size fractions of sandy media (e.g., Schnaar and Brusseau, 2005). Within the model, TCE-DNAPL dissolution is assumed negligible and the flow is uniform, consistent with the experimental methods employed.…”

“…following methods described in . The 45-50 mesh Ottawa Sand (see Section II.2.2.1) was selected to generate TCE-DNAPL ganglia (dyed with Oil-Red-O) that exist primarily as singlets (Schnaar and Brusseau, 2005;Ramsburg et al, 2011). Conservative, nonreactive tracer tests were conducted pre and post TCE-DNAPL emplacement to estimate dispersivity and confirm the uniformity of the emplaced DNAPL distribution .…”

“…Previous studies have measured the average singlet radius of entrapped NAPL for various sand fractions (Powers et al, 1992;Schnaar and Brusseau, 2005). Schnaar and Brusseau (2005) and Ramsburg et al (2011) developed regressions that relate an effective DNAPL drop radius to the saturation and textural characteristics of the granular medium.…”

“…Schnaar and Brusseau (2005) and Ramsburg et al (2011) developed regressions that relate an effective DNAPL drop radius to the saturation and textural characteristics of the granular medium. The correlation of Ramsburg et al (2011) is employed herein to estimate ganglia size.…”

Simulation of liquid–liquid interfaces in porous media

“…It is also important to describe the flow of liquids in the porous material. [6,7] The interfacial area of two immiscible fluids inside a porous media can be measured by two main methods: 1) the interfacial tracer technique [8][9][10][11][11][12][13][14][15] and 2) high-resolution microtomography [16][17][18]. On the other hand, numerical simulations and theoretical models are useful to gain a better understanding of the shape and extent of the interface and its relationship with parameters as porosity, grain size and contact angle.…”