Image analysis algorithms for estimating porous media multiphase flow variables from computed microtomography data: a validation study

Porter, Mark L.; Wildenschild, D.

doi:10.1007/s10596-009-9130-5

Cited by 79 publications

(48 citation statements)

References 52 publications

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“…The present work also outlined how to convert this segmented image into a pore network by extracting the pertinent information such as connectivity, pore sizes, and throat sizes. This process of calculating network properties from the watershed image was by no means the final word on the matter [47,48,63], and many improvements could be made such as finding surface area [64] and perimeter more rigorously. The networks extracted using the SNOW algorithm were compared to several known materials (see Table II).…”

Section: Discussionmentioning

confidence: 99%

Versatile and efficient pore network extraction method using marker-based watershed segmentation

2017

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Obtaining structural information from tomographic images of porous materials is a critical component of porous media research. Extracting pore networks is particularly valuable since it enables pore network modeling simulations which can be useful for a host of tasks from predicting transport properties to simulating performance of entire devices. This work reports an efficient algorithm for extracting networks using only standard image analysis techniques. The algorithm was applied to several standard porous materials ranging from sandstone to fibrous mats, and in all cases agreed very well with established or known values for pore and throat sizes, capillary pressure curves, and permeability. In the case of sandstone, the present algorithm was compared to the network obtained using the current state-of-the-art algorithm, and very good agreement was achieved. Most importantly, the network extracted from an image of fibrous media correctly predicted the anisotropic permeability tensor, demonstrating the critical ability to detect key structural features. The highly efficient algorithm allows extraction on fairly large images of 500 3 voxels in just over 200 s. The ability for one algorithm to match materials as varied as sandstone with 20% porosity and fibrous media with 75% porosity is a significant advancement. The source code for this algorithm is provided.

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Section: Discussionmentioning

confidence: 99%

Versatile and efficient pore network extraction method using marker-based watershed segmentation

2017

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“…For interfacial area calculations, we refer to ref. 26. The change in interfacial energy ΔE of the oil phase was 0.73 of the initial energy of the trapped oil before fragmentation (6.4 × 10 −7 J).…”

Section: Analysis Of Fragmented Oil Dropletsmentioning

confidence: 91%

“…The previously unidentified displacement mechanism has implications for (i) enhanced oil recovery, (ii) remediation of nonaqueous liquid contaminants in aquifers, and (iii) subsurface CO 2 storage. such as bead packs (22), sand packs (22)(23)(24)(25)(26), and sandstones (8,18,21,23), but less attention has been paid to carbonate rocks. However, more than 50% of the world's remaining oil reserves are located in carbonate reservoirs (27), and carbonate aquifers supply water wholly or partially to one quarter of the global population (28).…”

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confidence: 99%

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Pak

Butler

Geiger

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

153

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Using X-ray computed microtomography, we have visualized and quantified the in situ structure of a trapped nonwetting phase (oil) in a highly heterogeneous carbonate rock after injecting a wetting phase (brine) at low and high capillary numbers. We imaged the process of capillary desaturation in 3D and demonstrated its impacts on the trapped nonwetting phase cluster size distribution. We have identified a previously unidentified pore-scale event during capillary desaturation. This pore-scale event, described as droplet fragmentation of the nonwetting phase, occurs in larger pores. It increases volumetric production of the nonwetting phase after capillary trapping and enlarges the fluid−fluid interface, which can enhance mass transfer between the phases. Droplet fragmentation therefore has implications for a range of multiphase flow processes in natural and engineered porous media with complex heterogeneous pore spaces.droplet fragmentation | X-ray computed microtomography | pore-scale imaging | heterogeneous porous media | carbonate rock M ultiphase fluid displacement processes in porous media are important for a broad range of natural and engineering applications such as transport of nonaqueous phase liquid contaminants in aquifers, oil and gas production from hydrocarbon reservoirs, subsurface CO 2 storage, or gas transport in fuel cells. Herein, capillary trapping is a fundamental mechanism that causes immobilization of a portion of the resident nonwetting phase when it is displaced by an invading wetting phase. As a result, production of the nonwetting phase is always less than 100%.The pore-scale physics of capillary trapping are broadly understood, as the underlying mechanisms such as piston-like displacement, snap-off and film development have been observed in physical micromodel experiments and quantitative theories have been established for them (1-4). The conventional view considers such pore-scale processes to occur between multiple pores, i.e., they are interpore processes and the pores are defined as volumes connected by narrower pore throats. By contrast, intrapore processes, as presented in this paper, are not well established in the literature. During drainage (i.e., where a nonwetting phase displaces the wetting phase), the wetting phase can establish films in the corners of the pores, which results in its continuous production and hence low residual saturations of the wetting phase. During imbibition (i.e., where the wetting phase displaces a nonwetting phase), swelling of the corner wetting films causes snap-off of the nonwetting phase, which results in capillary trapping of the nonwetting phase. The trapped nonwetting phase exists as disconnected ganglia within the pore network. Numerical pore network models have been developed to include these porelevel mechanisms with the aim of predicting the macroscopic flow properties of porous materials such as the structure of the phase distributions, residual saturation, relative permeability functions, and capillary pressure curves. Some of these mod...

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“…Various techniques have been used to obtain the most accurate threshold value, such as k-means cluster analysis used by Porter and Wildenschild (2010); local thresholding criteria based on indicator kriging mentioned in Prodanović et al (2007); and the Otsu method used by Otsu (1979).…”

Section: Segmentation and Quantificationmentioning

confidence: 99%

Experimental investigation of residual saturation in mixed-wet porous media using a pore-scale approach

Larpudomlert

Torrealba

Karpyn

et al. 2013

J Petrol Explor Prod Technol

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Wettability is an important factor in terms of flow distribution and the amount of oil left behind in a petroleum reservoir after primary, secondary, and tertiary recovery processes. In fact, most alkaline flooding operations are aimed at wettability reversal. Therefore, a good understanding of how wettability, and other relevant factors (e.g., fluid saturation and porosity), affects displacement efficiency and fluid distribution at the pore-scale can lead to successful predictions of flow properties at the macroscale. In this study, pore-scale two-phase fluid flow in a synthetic mixed-wet granular media was investigated using X-ray microCT. Analysis of residual fluid structures in granular media composed of a mixture of glass and plastic beads (ranging from 0.4 to 0.6 mm in diameter) showed that the number of trapped water blobs was 2.4 times greater than that of oil, whereas most of the blobs were between 0.0001 and 0.001 mm 3 in size (i.e., 100 times smaller than in the case of uniform wettability), and were smaller than the mean pore volume (0.03 mm 3 ). The ratio of surface area to blob volume showed a slight tendency of water blobs to wet a higher surface area of the grains than oil blobs, for blob volumes larger than the mean pore size; this phenomenon can be attributed to stronger wetting affinity of the glass grains to the water phase than that of the plastic grains to the oil phase. Furthermore, statistical analysis of the distance between residual oil and water blobs to each solid surface confirms preferential wetting affinity of oil and water to plastic and glass surfaces, respectively.

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Image analysis algorithms for estimating porous media multiphase flow variables from computed microtomography data: a validation study

Cited by 79 publications

References 52 publications

Versatile and efficient pore network extraction method using marker-based watershed segmentation

Versatile and efficient pore network extraction method using marker-based watershed segmentation

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Experimental investigation of residual saturation in mixed-wet porous media using a pore-scale approach

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