Pore‐scale displacement mechanisms as a source of hysteresis for two‐phase flow in porous media

Schlüter, Steffen; Berg, Steffen; Rücker, Maja; Armstrong, Ryan T.; Vogel, Hans‐Jörg; Hilfer, R.; Wildenschild, D.

doi:10.1002/2015wr018254

Cited by 176 publications

(131 citation statements)

References 51 publications

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“…The main reason for this is that the information in the P c and k r curves which are often used as the only validation is extremely densely encoded: many aspects of the porous medium and the fluid behavior are lumped into too few parameters to completely characterize the behavior. P c and k r curves are traditionally described as functions of only water saturation, rather than taking all true state variables into account [18,19].…”

Section: Published By the American Physical Society Under The Terms Omentioning

confidence: 99%

“…The Euler number is a topological invariant which can be used to characterize the topology of complex shapes and has therefore been used extensively to characterize the nonwetting phase topology in two-phase flow studies [19,21,59]. The Euler number χ of a general nonplanar graph can be defined as χ = v − e with v the number of vertices (in our case, oil-filled pores) and e the number of edges (oil-filled throats) [62].…”

Section: Euler Number Analysismentioning

confidence: 99%

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Validation of model predictions of pore-scale fluid distributions during two-phase flow

et al. 2018

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Pore-scale two-phase flow modeling is an important technology to study a rock's relative permeability behavior. To investigate if these models are predictive, the calculated pore-scale fluid distributions which determine the relative permeability need to be validated. In this work, we introduce a methodology to quantitatively compare models to experimental fluid distributions in flow experiments visualized with microcomputed tomography. First, we analyzed five repeated drainage-imbibition experiments on a single sample. In these experiments, the exact fluid distributions were not fully repeatable on a pore-by-pore basis, while the global properties of the fluid distribution were. Then two fractional flow experiments were used to validate a quasistatic pore network model. The model correctly predicted the fluid present in more than 75% of pores and throats in drainage and imbibition. To quantify what this means for the relevant global properties of the fluid distribution, we compare the main flow paths and the connectivity across the different pore sizes in the modeled and experimental fluid distributions. These essential topology characteristics matched well for drainage simulations, but not for imbibition. This suggests that the pore-filling rules in the network model we used need to be improved to make reliable predictions of imbibition. The presented analysis illustrates the potential of our methodology to systematically and robustly test two-phase flow models to aid in model development and calibration.

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Section: Published By the American Physical Society Under The Terms Omentioning

confidence: 99%

Section: Euler Number Analysismentioning

confidence: 99%

Validation of model predictions of pore-scale fluid distributions during two-phase flow

et al. 2018

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“…To this end, recent advances in pore-scale imaging-based characterization methods (see review [26]) that enable the fast visualization of two-phase flow at pore-scale resolution, most notably microscopy imaging of thin micromodels [18,[27][28][29], X-ray computed tomography [30][31][32][33][34], and confocal microscopy [35,36], have provided valuable insights into 2 Geofluids the interplay of viscous, capillary, gravitational, and inertial forces constituting the complexity of interface dynamics at the pore-scale. For instance, free-energy driven Haines jumps have been confirmed as dominant displacement mechanism for flow at small capillary numbers [29,32].…”

Section: Introductionmentioning

confidence: 99%

Fluid Interfaces during Viscous-Dominated Primary Drainage in 2D Micromodels Using Pore-Scale SPH Simulations

Sivanesapillai

Steeb

2018

Geofluids

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We perform pore-scale resolved direct numerical simulations of immiscible two-phase flow in porous media to study the evolution of fluid interfaces. Using a Smoothed-Particle Hydrodynamics approach, we simulate saturation-controlled primary drainage in heterogeneous, partially wettable 2D porous microstructures. While imaging the evolution of fluid interfaces near capillary equilibrium becomes more feasible as fast X-ray tomography techniques mature, imaging methods with suitable temporal resolution for viscous-dominated flow have only recently emerged. In this work, we study viscous fingering and stable displacement processes. During viscous fingering, pore-scale flow fields are reminiscent of Bretherton annular flow, that is, the less viscous phase percolates through the core of a pore-throat forming a hydrodynamic wetting film. Even in simple microstructures wetting films have major impact on the evolution of fluid interfacial area and are observed to give rise to nonnegligible interfacial viscous coupling. Although macroscopically appearing flat, saturation fronts during stable displacement extend over the length of the capillary dispersion zone. While far from the dispersion zone fluid permeation obeys Darcy's law, the interplay of viscous and capillary forces is found to render fluid flow within complex. Here we show that the characteristic length scale of the capillary dispersion zone increases with the heterogeneity of the microstructure.

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“…Some orientation is given by findings of Hincapié and Germann (2010) and Moebius and Or (2012). Promising techniques like time-lapse X-ray or µCT tomography just emerge to be applied (Koestel and Larsbo, 2014;Schlüter et al, 2016). Yet there is consensus that macroporematrix interaction depends on the matric head, the wetting of the macropore wall (Klaus et al, 2013) and is optionally affected 10 by organic coatings which may act hydrophobic (Jarvis, 2007;Rogasik et al, 2014).…”

Section: Macropore-matrix-interactionmentioning

confidence: 99%

“…Pore scale processes (e.g. Moebius and Or, 2012;Shahraeeni and Or, 2012;Snehota et al, 2015;Schlüter et al, 2016) are not resolved here.…”

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confidence: 99%

Ecohydrological particle model based on representative domains

Jackisch¹,

Zehe²

2017

Preprint

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Abstract. Non-uniform infiltration and subsurface flow in structured soils is observed in most natural settings. It arises from imperfect lateral mixing of fast advective flow in structures and diffusive flow in the soil matrix and remains one of the most challenging topics with respect to match observation and modelling of water and solutes at the plot scale.This study extends the fundamental introduction of a space-domain random walk of water particles as alternative approach to the Richards equation for diffusive flow (Zehe and Jackisch, 2016) to a stochastic-physical model framework simulating 5 soil water flow in a representative, structured soil domain. The central objective of the proposed model is the simulation of non-uniform flow fingerprints in different ecohydrological settings and antecedent states by making maximum use of field observables for parameterisation. Avoiding non-observable parameters for macropore-matrix exchange, an energy-balance approach to govern film flow in representative flow paths is employed. We present the echoRD model (ecohydrological particle model based on representative domains) and a series of application test cases. 10The model proves as a powerful alternative to existing dual-domain models, driven on experimental data and with selfcontrolled, dynamic macropore-matrix exchange from the topologically semi-explicitly defined structures.

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Pore‐scale displacement mechanisms as a source of hysteresis for two‐phase flow in porous media

Cited by 176 publications

References 51 publications

Validation of model predictions of pore-scale fluid distributions during two-phase flow

Validation of model predictions of pore-scale fluid distributions during two-phase flow

Fluid Interfaces during Viscous-Dominated Primary Drainage in 2D Micromodels Using Pore-Scale SPH Simulations

Ecohydrological particle model based on representative domains

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