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Insights into non-Fickian solute transport in carbonates.

Bijeljic B, Mostaghimi P, Blunt MJ - Water Resour Res (2013)

Bottom Line: Mostaghimi, and M.Blunt (2013), Insights into non-Fickian solute transport in carbonates, Water Resour.Res., 49, 2714-2728, doi:10.1002/wrcr.20238.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Science and Engineering, Imperial College London London, UK.

ABSTRACT
[1] We study and explain the origin of early breakthrough and long tailing plume behavior by simulating solute transport through 3-D X-ray images of six different carbonate rock samples, representing geological media with a high degree of pore-scale complexity. A Stokes solver is employed to compute the flow field, and the particles are then transported along streamlines to represent advection, while the random walk method is used to model diffusion. We compute the propagators (concentration versus displacement) for a range of Peclet numbers (Pe) and relate it to the velocity distribution obtained directly on the images. There is a very wide distribution of velocity that quantifies the impact of pore structure on transport. In samples with a relatively narrow spread of velocities, transport is characterized by a small immobile concentration peak, representing essentially stagnant portions of the pore space, and a dominant secondary peak of mobile solute moving at approximately the average flow speed. On the other hand, in carbonates with a wider velocity distribution, there is a significant immobile peak concentration and an elongated tail of moving fluid. An increase in Pe, decreasing the relative impact of diffusion, leads to the faster formation of secondary mobile peak(s). This behavior indicates highly anomalous transport. The implications for modeling field-scale transport are discussed. Citation: Bijeljic, B., P. Mostaghimi, and M. J. Blunt (2013), Insights into non-Fickian solute transport in carbonates, Water Resour. Res., 49, 2714-2728, doi:10.1002/wrcr.20238.

No MeSH data available.


Throat radius distributions obtained from MICP measurements for (a) Ketton, Mt Gambier, and ME2 and (b) Indiana, Estaillades, and ME1. The straight black solid lines in (a) and (b) mark half the voxel size (3.85 µm) for images of Indiana, Estaillades, ME1, ME2, and Ketton. The dashed line in (b) marks half the voxel size (4.5 µm) for the image of Mt Gambier, while the dashed line in (a) marks half the voxel size (1.65 µm) for the high-resolution image of Estaillades. This is the smallest throat radius that can be detected in the images.
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fig02: Throat radius distributions obtained from MICP measurements for (a) Ketton, Mt Gambier, and ME2 and (b) Indiana, Estaillades, and ME1. The straight black solid lines in (a) and (b) mark half the voxel size (3.85 µm) for images of Indiana, Estaillades, ME1, ME2, and Ketton. The dashed line in (b) marks half the voxel size (4.5 µm) for the image of Mt Gambier, while the dashed line in (a) marks half the voxel size (1.65 µm) for the high-resolution image of Estaillades. This is the smallest throat radius that can be detected in the images.

Mentions: [16] Mercury injection capillary pressure (MICP) was measured at a commercial laboratory (Weatherford) on samples taken from the same block of stone from which the images were obtained. Figures 2a and 2b show the inferred throat radius distributions normalized to a maximum value obtained from MICP for (a) Ketton, Mt Gambier, and ME2 and (b) Estaillades, Indiana, and ME1. Plotted also are the straight black solid and dashed lines that mark half the voxel size of the images studied, representing the smallest throat radius that can be detected in the images.


Insights into non-Fickian solute transport in carbonates.

Bijeljic B, Mostaghimi P, Blunt MJ - Water Resour Res (2013)

Throat radius distributions obtained from MICP measurements for (a) Ketton, Mt Gambier, and ME2 and (b) Indiana, Estaillades, and ME1. The straight black solid lines in (a) and (b) mark half the voxel size (3.85 µm) for images of Indiana, Estaillades, ME1, ME2, and Ketton. The dashed line in (b) marks half the voxel size (4.5 µm) for the image of Mt Gambier, while the dashed line in (a) marks half the voxel size (1.65 µm) for the high-resolution image of Estaillades. This is the smallest throat radius that can be detected in the images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814002&req=5

fig02: Throat radius distributions obtained from MICP measurements for (a) Ketton, Mt Gambier, and ME2 and (b) Indiana, Estaillades, and ME1. The straight black solid lines in (a) and (b) mark half the voxel size (3.85 µm) for images of Indiana, Estaillades, ME1, ME2, and Ketton. The dashed line in (b) marks half the voxel size (4.5 µm) for the image of Mt Gambier, while the dashed line in (a) marks half the voxel size (1.65 µm) for the high-resolution image of Estaillades. This is the smallest throat radius that can be detected in the images.
Mentions: [16] Mercury injection capillary pressure (MICP) was measured at a commercial laboratory (Weatherford) on samples taken from the same block of stone from which the images were obtained. Figures 2a and 2b show the inferred throat radius distributions normalized to a maximum value obtained from MICP for (a) Ketton, Mt Gambier, and ME2 and (b) Estaillades, Indiana, and ME1. Plotted also are the straight black solid and dashed lines that mark half the voxel size of the images studied, representing the smallest throat radius that can be detected in the images.

Bottom Line: Mostaghimi, and M.Blunt (2013), Insights into non-Fickian solute transport in carbonates, Water Resour.Res., 49, 2714-2728, doi:10.1002/wrcr.20238.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Science and Engineering, Imperial College London London, UK.

ABSTRACT
[1] We study and explain the origin of early breakthrough and long tailing plume behavior by simulating solute transport through 3-D X-ray images of six different carbonate rock samples, representing geological media with a high degree of pore-scale complexity. A Stokes solver is employed to compute the flow field, and the particles are then transported along streamlines to represent advection, while the random walk method is used to model diffusion. We compute the propagators (concentration versus displacement) for a range of Peclet numbers (Pe) and relate it to the velocity distribution obtained directly on the images. There is a very wide distribution of velocity that quantifies the impact of pore structure on transport. In samples with a relatively narrow spread of velocities, transport is characterized by a small immobile concentration peak, representing essentially stagnant portions of the pore space, and a dominant secondary peak of mobile solute moving at approximately the average flow speed. On the other hand, in carbonates with a wider velocity distribution, there is a significant immobile peak concentration and an elongated tail of moving fluid. An increase in Pe, decreasing the relative impact of diffusion, leads to the faster formation of secondary mobile peak(s). This behavior indicates highly anomalous transport. The implications for modeling field-scale transport are discussed. Citation: Bijeljic, B., P. Mostaghimi, and M. J. Blunt (2013), Insights into non-Fickian solute transport in carbonates, Water Resour. Res., 49, 2714-2728, doi:10.1002/wrcr.20238.

No MeSH data available.