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Petchsingto, Tawatchai; Karpyn, Zuleima T.

doi:10.1007/s10040-010-0632-y

Cited by 9 publications

(13 citation statements)

References 17 publications

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“…Yang et al [19] also pointed out the importance of in-plane curvature in accounting for capillary pressure in many cases. However, significant similarities could still be observed through the comparison of P-S relation obtained from the simulations based on the IP and MIP models, respectively [20]. Likewise, Li et al [21] suggested that the MIP model produced little improvement over the IP model owing to the high value of the curvature radius of the invading front.…”

Section: Geofluidsmentioning

confidence: 95%

Effect Study of Aperture Distribution on the Capillary Pressure-Saturation Relation for the Single Fracture

Wang

Zhou

2017

Geofluids

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A systematic numerical method was presented to investigate the effect of aperture distribution on the relation of capillary pressure versus fluid saturation (P-S relation) for a single fracture. The fracture was conceptualized as a two-dimensional lattice-grid model and its aperture field was described by a probability distribution. Based on the invasion percolation theory, a program was developed to simulate the quasi-static displacement. The simulation was verified validly by comparisons of the experimental results. The effects of the statistical parameters were further quantified. The results show that the largest local aperture on the fracture boundary determines the AEV. The larger mean decreases the variation coefficient, which causes the more uniform aperture field, smoother air invasion front, and steeper capillary pressure-saturation curve (CPSC). The larger standard deviation increases not only the range but also the contrast degree of the apertures, thus providing a nondeterministic rule in the P-S relation. The larger correlation length causes a more homogeneous aperture field and a dual connectivity of the fracture. The increase of the difference and contrast degree between the small and large apertures results in dual-aperture fields. The dual-aperture field and dual connectivity of the fracture both contribute to the bimodal characteristic of the CPSC.

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Section: Geofluidsmentioning

confidence: 95%

Effect Study of Aperture Distribution on the Capillary Pressure-Saturation Relation for the Single Fracture

Wang

Zhou

2017

Geofluids

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“…The IP algorithm considers the interface between the invading fluid and defending fluid, in this case the non-wetting and wetting fluids, respectively, computes the pressure required to invade each adjacent element, and the invading fluid "invades" the element with the lowest invasion pressure. The algorithm then repeats this computation and invasion step for each new interface location (Glass and Yarrington 1996;Ji et al 2003;Glass et al 2004;Petchsingto and Karpyn 2010). In this work, the invasion pressure is computed as a sum of the capillary pressure, P c , and the gravitational pressure, P g (Ioannidis et al 1996;Meakin et al 2000;Glass and Yarrington 2003).…”

Section: Ip Model Conceptualizationmentioning

confidence: 99%

“…IP has been used to model various physical growth processes such as capillary fingering (e.g., Wilkinson and Willemsen ), gravity fingering (e.g., Glass and Nicholl ; Glass and Yarrington , ), and fragmentation (e.g., Glass and Yarrington ) during the invasion of one fluid by another immiscible fluid. Modifications to the IP algorithm include utilizing the local in‐plane curvature and local fracture‐wall topography to improve the calculation of capillary pressure by including local variations in fracture geometry (Glass and Yarrington ; Glass et al ; Petchsingto and Karpyn ). Other modifications to the IP model include simultaneously allowing both the invading fluid to move into the defending fluid space and vice versa to account for fragmentation (reinvasion) of the non‐wetting phase during the invasion process (e.g., Wagner et al ; Tsimpanogiannis and Yortsos ; Mumford et al ), and the inclusion of trapping of one immiscible fluid by another (e.g., Wilkinson and Willemsen ; Ioannidis et al ; Meakin et al ).…”

Section: Introductionmentioning

confidence: 99%

On the Importance of Gravity in DNAPL Invasion of Saturated Horizontal Fractures

Cianflone

Dickson²,

Mumford

2016

Groundwater

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Invasion percolation (IP) models of dense non-aqueous phase liquid (DNAPL) invasion into saturated horizontal fractures typically neglect viscous and gravity forces, as it is assumed that capillarity dominates in many situations. An IP model simulating DNAPL invasion into saturated horizontal fractures was modified to include gravity as a local effect. The model was optimized using a genetic algorithm, and demonstrated that the inclusion of gravity is important for replicating the architecture of the DNAPL invasion pattern. The optimized gravity-included simulation showed the DNAPL invasion pattern to be significantly more representative of the experimentally observed pattern (80% accuracy) than did the optimized gravity-neglected simulation (70% accuracy). Additional simulations of DNAPL invasion in 360 randomly generated fractures were compared with and without gravity forces. These simulations showed that with increasing fracture roughness, the minimum difference between simulations with and without gravity increases to 35% for a standard deviation of the mid-aperture elevation field (SD ) of 10 mm. Even for low roughness (SD = 0.1 mm), the difference was as high as 30%. Furthermore, a scaled Bond Number is defined which includes data regarding DNAPL type, media type and statistical characteristics of the fracture. The value of this scaled Bond Number can be used to determine the conditions under which gravity should be considered when simulating DNAPL invasion in a macroscopically horizontal fracture. Finally, a set of equations defining the minimum and maximum absolute percentage difference between gravity-included and gravity-neglected simulations is presented based on the fracture and DNAPL characteristics.

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“…Over the past two decades, X-ray computed tomography (xCT) has become a valuable tool for 3D visualization and characterization of geological specimens [1][2][3][4][5][6][7][8][9], including fracture geometries [10][11][12][13][14][15][16][17][18][19][20][21], pore networks [22][23][24][25][26][27][28][29][30][31], crystal sizes [32,33], and mineral phases [3,[34][35][36][37][38][39]. xCT imaging is indispensable for non-destructive observation of geometry of fractures, which is important because fractures provide preferential flow conduits and often dominate mass transfer in geological materials.…”

Section: Introductionmentioning

confidence: 99%

“…xCT imaging has been used to provide valuable insights in core-flow experiments designed to investigate fractures in the context of geohydrological, geochemical, and geomechanical processes of the deep subsurface, such as CO 2 geological storage [20,30,40] and oil and gas operations [13-15, 17, 41-46]. Quantitative characterizations of fracture geometries have advanced our understanding of fracture hydrodynamics [13,17,21,[47][48][49], reactivity [11,24,25,35,36,47,[50][51][52][53], and mechanics [16,19,37].…”

Section: Introductionmentioning

confidence: 99%

Quantifying fracture geometry with X-ray tomography: Technique of Iterative Local Thresholding (TILT) for 3D image segmentation

2016

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This paper presents a new method-the Technique of Iterative Local Thresholding (TILT)-for processing 3D X-ray computed tomography (xCT) images for visualization and quantification of rock fractures. The TILT method includes the following advancements. First, custom masks are generated by a fracture-dilation procedure, which significantly amplifies the fracture signal on the intensity histogram used for local thresholding. Second, TILT is particularly well suited for fracture characterization in granular rocks because the multi-scale Hessian fracture (MHF) filter has been incorporated to distinguish fractures from pores in the rock matrix. Third, TILT wraps the thresholding and fracture isolation steps in an optimized iterative routine for binary segmentation, minimizing human intervention and enabling automated processing of large 3D datasets. As an illustrative example, we applied TILT to 3D xCT images of reacted and unreacted fractured limestone cores. Other segmentation methods were also applied to provide insights regarding variability in image processing. The results show that TILT significantly enhanced separability of grayscale intensities, outperformed the other methods in automation, and was successful in isolating fractures from the porous rock matrix. Because the other methods are more likely to misclassify fracture edges as void and/or have limited capacity in distinguishing fractures from pores, those methods estimated larger fracture volumes (up to 80 %), surface areas (up to 60 %), and roughness (up to a factor of 2). These differences in fracture geometry would lead to significant disparities in hydraulic permeability predictions, as determined by 2D flow simulations.

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Untitled

Cited by 9 publications

References 17 publications

Effect Study of Aperture Distribution on the Capillary Pressure-Saturation Relation for the Single Fracture

Effect Study of Aperture Distribution on the Capillary Pressure-Saturation Relation for the Single Fracture

On the Importance of Gravity in DNAPL Invasion of Saturated Horizontal Fractures

Quantifying fracture geometry with X-ray tomography: Technique of Iterative Local Thresholding (TILT) for 3D image segmentation

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