Characterizing locality- and scale-dependent heterogeneity in conglomerate core and associated fluid flow using X-ray CT imaging

Han, Gidon; Han, Weon Shik; Kim, Kue‐Young; Baek, Johyun; Kim, Minji; Kim, Chan Yeong; Lim, Jae‐Hong

doi:10.1016/j.jhydrol.2021.126736

Cited by 10 publications

(7 citation statements)

References 31 publications

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“…The current micro-CT technique restricts the imaging volume, which highly depends on the configured resolution. It means that the imaging volume must be reduced to a millimeter scale if a high resolution of O(1) μm is desirable . Some concerns were raised regarding the limited volume since such a small subsample cannot capture the broad pore size distribution and the large-scale heterogeneity in the core plugs, such as vugs and fractures in carbonates and the gravel distribution in conglomerates .…”

Section: Introductionmentioning

confidence: 99%

“…Currently, the permeability upscaling studies for the carbonate rocks with large-scale fractures and vugs are not well addressed. Meanwhile, little attention was given to the conglomerate rock, which contains the heterogeneous distribution of the almost impermeable gravel (gravel size > 2 mm) and microporous sandy matrix (sand size < 2 mm) . It is evident that the gravel blocks the fluid flow, while the fracture/vug easily induces the preferential flow.…”

Section: Introductionmentioning

confidence: 99%

“…It means that the imaging volume must be reduced to a millimeter scale if a high resolution of O(1) μm is desirable. 16 Some concerns were raised regarding the limited volume since such a small subsample cannot capture the broad pore size distribution and the large-scale heterogeneity in the core plugs, such as vugs and fractures in carbonates 17 and the gravel distribution in conglomerates. 16 When increasing the scanning resolution to O (10) μm, the imaging volume can enlarge to the centimeter scale, while most micropores cannot be resolved at the low resolution.…”

Section: Introductionmentioning

confidence: 99%

“…16 Some concerns were raised regarding the limited volume since such a small subsample cannot capture the broad pore size distribution and the large-scale heterogeneity in the core plugs, such as vugs and fractures in carbonates 17 and the gravel distribution in conglomerates. 16 When increasing the scanning resolution to O (10) μm, the imaging volume can enlarge to the centimeter scale, while most micropores cannot be resolved at the low resolution. 18 The heterogeneity covering a wide range of length scales is believed to introduce the permeability discrepancy between the conventional DRA and experiment measurements.…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, little attention was given to the conglomerate rock, which contains the heterogeneous distribution of the almost impermeable gravel (gravel size > 2 mm) and microporous sandy matrix (sand size < 2 mm). 16 It is evident that the gravel blocks the fluid flow, while the fracture/vug easily induces the preferential flow. The fluid flow due to gravel-matrix heterogeneity in the conglomerates significantly varies from the fracture/vug-matrix heterogeneity in the carbonates.…”

Section: Introductionmentioning

confidence: 99%

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Multiscale Digital Rock Imaging and Modeling for Measuring the Heterogeneous Carbonate and Conglomerate Permeability at the Laboratory Plug Scale

Guan²,

Zhang³

et al. 2022

Energy Fuels

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Rock permeability is an essential petrophysical property for evaluating the hydrocarbon exploitation and CO2 geological sequestration. The large-scale rock heterogeneity by single-scale digital rock analysis (DRA) poses a challenge in predicting the permeability of the centimeter-scale core plug for fractured carbonates, vuggy carbonates, and conglomerates. The present study developed two multiscale workflows to upscale the permeability from the millimeter scale to the near centimeter scale. The basic two-step workflow consists of multiscale imaging and multiscale modeling to integrate the Darcy flow in the microporous matrix representative element volume and the Stokes flow in larger-sized pores/vugs/fractures. The basic two-step workflow was then extended to the four-step workflow to speed up the computation and reduce the computer memory. With experimental permeability as the benchmark, this study compared single-scale simulation methods and multiscale workflows to quantify the best permeability analysis method for the three rock types. The basic two-step workflow with binary segmentation is accurate for the fractured carbonate due to fully modeling the preferential flow and the fluid exchange between the fracture and matrix. The extended four-step workflow with ternary segmentation is optimal for the conglomerate to simulate fluid resistances of the gravel and matrix with satisfied computational efficiency. The permeability of some vuggy carbonates can be well evaluated by the single-scale simulation of the matrix flow where the vugs are isolated and cannot facilitate fluid communication. The acceptable agreement between the experimental and simulated permeabilities for 18 core plugs improves the confidence in using the developed DRA to predict the permeability for complex rocks.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%