Diffusion in brine‐saturated reservoir cores studied by NMR imaging

Gibbs, S. Julian; Attard, J. J.; Hall, Laurance D.

doi:10.1002/aic.690390417

Cited by 9 publications

(1 citation statement)

References 31 publications

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“…Geological systems (e.g., water-saturated porous soils or rocks) are usually heterogeneous, and the transport properties of such porous media vary significantly from position to position within the system (e.g., Gibbs et al, 1993). Thus, it is important to map the three-dimensional (3D) distribution of transport properties (e.g., diffusivity and porosity) in order to fully understand the processes involved in contaminant hydrogeology.…”

Section: Introductionmentioning

confidence: 99%

DMAP.m: A Mathematica® program for three-dimensional mapping of tortuosity and porosity of porous media.

Nakashima

Yamaguchi²

2004

Bull. Geol. Surv. Japan

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(2004) DMAP.m: A Mathematica® program for three-dimensional mapping of tortuosity and porosity of porous media. Bull. Geol. Surv. Japan, vol. 55 (3/ 4), 93-103, 10 figs, 3 tables. Abstract:We developed a Mathematica® program for three-dimensional mapping of the porosity and normalized apparent diffusion coefficient (tortuosity) of isotropic heterogeneous porous media. The program, DMAP.m, is a package-type program for Mathematica® version 4 or later. DMAP.m accepts three-dimensional (3D) digital image data for the porous media as an input. Such data may be obtained by, for example, X-ray computed tomography (CT) as a set of text files of two-dimensional contiguous CT slices (square matrices). DMAP.m reads the text files and divides the image set into sub-cubes, then executes a non-sorbing random walk (lattice walk) through the discrete pore space in each sub-cube. A specified number of voxels are chosen randomly as the start position of the random walk. If the chosen voxel falls within a pore, random walk simulation is carried out until the walker exits the sub-cube. If the chosen voxel falls within a solid, the random walk is not performed. The porosity of each sub-cube is calculated as the probability of a successful hit on a pore voxel in this random choice of the start position (Monte Carlo integral). The time required for the walkers to escape from each sub-cube is recorded in the random walk simulation, representing an "out-diffusion" or "out-leaching" numerical simulation. The tortuosity (apparent diffusion coefficient in the free space divided by that in porous media) is calculated by fitting the time-dependent cumulative number of walkers that have escaped from the sub-cube to a theoretical curve. DMAP.m was applied successfully here to the 3D X-ray CT image of a monosized sand pack. DMAP.m is available for free download on the author's website (URL = http://staff.aist.go.jp/nakashima.yoshito/progeng.htm) to facilitate study on porous media by X-ray CT or nuclear magnetic resonance imaging.

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Section: Introductionmentioning

confidence: 99%