Impact of sample geometry on the measurement of pressure‐saturation curves: Experiments and simulations

Moura, Marcel; Fiorentino, Eve-Agnès; Måløy, Knut Jørgen; Schäfer, Gerhard; Toussaint, Renaud

doi:10.1002/2015wr017196

Cited by 29 publications

(73 citation statements)

References 53 publications

(81 reference statements)

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“…Example displacements include piston-like invasion in straight capillary tubes, where work exerted on the fluid/rock system balances the change in interfacial free energy. The irreversible P c (S) segments (rheons) induce hysteresis [Morrow, 1970]. They represent spontaneous redistributions of fluid at almost constant saturation due to instabilities arising when an interface cannot change curvature smoothly with capillary pressure, resulting in abrupt pressure jumps.…”

Section: Pressure-and Saturation-controlled Displacementmentioning

confidence: 99%

“…On the pore scale, capillary forces usually dominate over gravity and viscous forces due to the small flow rates, length scales, and pore sizes involved [Hilfer and Øren, 1996]. Thus, it is natural to interpret P c (S) curves as a sequence of capillary-dominated pore-scale displacements representing transitions between local energy minima that occur in the form of alternate reversible and irreversible events, called "isons" and "rheons," respectively [Morrow, 1970;Cueto-Felgueroso and Juanes, 2016]. The standard simulation approach to such displacements is quasi-static methods that assume capillary forces alone control interface motion and approximate the process by a series of equilibrium states (local energy minima) at imposed capillary pressures [e.g., Øren et al, 1998;Hilpert and Miller, 2001;Jettestuen et al, 2013;Xu and Louge, 2015].…”

Section: Introductionmentioning

confidence: 99%

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Footprints of spontaneous fluid redistribution on capillary pressure in porous rock

Helland

Friis

Jettestuen

et al. 2017

Geophysical Research Letters

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Pore‐scale imaging of two‐phase flow in porous media shows that pore filling occurs as cooperative events with accompanying spontaneous fluid redistribution in other parts of the pore space. We present a level set method that controls saturation quasi‐statically to model experiments controlled by low, constant flow rates and demonstrate that our method can describe the observed displacement mechanisms. The level set approach determines states of capillary equilibrium, which generally are different for displacement protocols constrained by saturation and pressure. Saturation‐controlled simulations of drainage in sandstone show spontaneous fluid redistributions with abrupt pressure jumps and cooperative behavior, including snap‐off and interface retraction events, consistent with experimental observations. Drainage capillary pressure curves are lower when saturation, rather than pressure, controls displacement. Remarkably, these effects are less significant for imbibition processes where the development of hydraulically connected wetting phase moderates the cooperative behavior and associated pressure jumps.

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Section: Pressure-and Saturation-controlled Displacementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Footprints of spontaneous fluid redistribution on capillary pressure in porous rock

Helland

Friis

Jettestuen

et al. 2017

Geophysical Research Letters

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“…In analogy to what was done in [50,78], pore-throat size distributions of computational unit cells are computed on the basis of a Delaunay triangulation of grain center points ( Figure 9). The pore-throat size between two neighboring grains is considered equal to the length of the connecting Delaunay edge upon subtracting respective grain radii.…”

Section: Hydraulic and Morphological Properties Of Microstructuresmentioning

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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“…For example, one observes flow regimes such as two-phase flow in rigid porous media [40][41][42][43][44], capillary fracturing, stick-slip bubbles, and labyrinth patterns [31][32][33][34][35][36][37][38][39]. In the opposite case, during liquid injection into dry granular media [45], for a given imposed flux, the flow behavior goes from stable invasion toward saturated granular fingers for increasing flow rate and viscosity of the invading fluid.…”

Section: Introductionmentioning

confidence: 99%

“…Further, during air injection into liquid saturated granular media and suspensions, the characteristics of emerging patterns and behavior of the media depend on injection rate and the competition between mobilized friction and surface forces [31][32][33][34][35][36][37][38][39][40][41][42][43][44]. For example, one observes flow regimes such as two-phase flow in rigid porous media [40][41][42][43][44], capillary fracturing, stick-slip bubbles, and labyrinth patterns [31][32][33][34][35][36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Pneumatic fractures in confined granular media

et al. 2017

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We perform experiments where air is injected at a constant overpressure P in , ranging from 5 to 250 kPa, into a dry granular medium confined within a horizontal linear Hele-Shaw cell. The setup allows us to explore compacted configurations by preventing decompaction at the outer boundary, i.e., the cell outlet has a semipermeable filter such that beads are stopped while air can pass. We study the emerging patterns and dynamic growth of channels in the granular media due to fluid flow, by analyzing images captured with a high speed camera (1000 images/s). We identify four qualitatively different flow regimes, depending on the imposed overpressure, ranging from no channel formation for P in below 10 kPa, to large thick channels formed by erosion and fingers merging for high P in around 200 kPa. The flow regimes where channels form are characterized by typical finger thickness, final depth into the medium, and growth dynamics. The shape of the finger tips during growth is studied by looking at the finger width w as function of distance d from the tip. The tip profile is found to follow w(d) ∝ d β , where β = 0.68 is a typical value for all experiments, also over time. This indicates a singularity in the curvaturee., more rounded tips rather than pointy cusps, as they would be for the case β > 1. For increasing P in , the channels generally grow faster and deeper into the medium. We show that the channel length along the flow direction has a linear growth with time initially, followed by a power-law decay of growth velocity with time as the channel approaches its final length. A closer look reveals that the initial growth velocity v 0 is found to scale with injection pressure as v 0 ∝ P 3 2 in , while at a critical time t c there is a cross-over to the behavior v(t) ∝ t −α , where α is close to 2.5 for all experiments. Finally, we explore the fractal dimension of the fully developed patterns. For example, for patterns resulting from intermediate P in around 100-150 kPa, we find that the box-counting dimensions lie within the range D B ∈ [1.53,1.62], similar to viscous fingering fractals in porous media.

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Impact of sample geometry on the measurement of pressure‐saturation curves: Experiments and simulations

Cited by 29 publications

References 53 publications

Footprints of spontaneous fluid redistribution on capillary pressure in porous rock

Footprints of spontaneous fluid redistribution on capillary pressure in porous rock

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

Pneumatic fractures in confined granular media

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