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Magnetic-resonance imaging and simplified Kozeny-Carman-model analysis of glass-bead packs as a frame of reference to study permeability of reservoir rocks
- Wang, Dayong, Han, Dongyan, Li, Wenqiang, Zheng, Zhanpeng, Song, Yongchen
- Hydrogeology journal 2017 v.25 no.5 pp. 1465-1476
- image analysis, magnetic resonance imaging, models, permeability, porosity, quartz, sandstone, surface area
- Permeability variation in reservoir rocks results from the combined effects of various factors, and makes porosity–permeability (ϕ–k) relationships more complex, or, in some cases, non-existent. In this work, the ϕ–k relationship of macroscopically homogeneous glass-bead packs is deduced based on magnetic resonance imaging (MRI) measurement and Kozeny-Carman (K-C) model analysis; these are used as a frame of reference to study permeability of reservoir rocks. The results indicate: (1) most of the commonly used simplified K-C models (e.g. the simplified traditional (omitting specific surface area), high-order, threshold, and fractal models) are suitable for estimating permeability of glass-bead packs. The simplified traditional model does not present obvious dependence on rock samples. Whether for the glass-bead packs or clean natural sandstones, the sample coefficients almost remain invariant. Comparably, the high-order, the fractal, and the threshold models are strongly sample-specific and cannot be extrapolated from the glass-bead packs to natural sandstones; (2) the ϕ–k relationships of quartz sands and silty sandstones resemble those of the glass-bead packs, but they significantly deviate from the K-C models at low porosities due to small pore entry radius; (3) a small amount of intergranular cements (<10%v) does not affect the general variation trend of permeability with porosity but can potentially increase predictive errors of the K-C models, whereas in the case of more cements, the ϕ–k relationships of sandstones become uncertain and cannot be described by any of these K-C models.