scholarly journals Viscous Fingering and Gravity Segregation through Porous Media: Experimental Findings

2010 ◽  
Vol 14 (11) ◽  
pp. 1-13 ◽  
Author(s):  
Farhat Abbas ◽  
Derek A. Rose
Keyword(s):  
Porous Media ◽  
Oil Recovery ◽  
Preferential Flow ◽  
Saline Water ◽  
Viscous Fingering ◽  
Breakthrough Curves ◽  
Bulk Solution ◽  
Hydrodynamic Dispersion ◽  
Vertical Flow ◽  
Gravity Segregation

Abstract During downward vertical flow of a viscous solution, the viscous fingering (VF) phenomenon affects miscible displacement of solutes through a soil profile. On the other hand, during horizontal flow, when the liquid residing in a horizontal bed of porous materials is displaced by another liquid of different density, the resulting hydrodynamic dispersion is modified by the formation of a tongue of denser liquid undershooting the less dense liquid, a phenomenon known as gravity segregation (GS). To explore VF and GS phenomena, the authors present laboratory experimental results on the vertical and horizontal transport of bulk solution and ions of different concentrations and/or densities through inert and reactive porous media. The study showed that, with miscible liquids, breakthrough starts later and ends earlier. The authors predicted the behavior of immiscible liquids by the nondimensional gravity segregation number β: that is, with increase in β, the segregation becomes extreme. The curve fitting technique CXTFIT 2.0 fitted the experimental breakthrough curves well, showing that the apparent coefficients of hydrodynamic dispersion vary much less with pore-water velocity in horizontal than in vertical flow, but retardation factors are not influenced by the orientation of flow. This work is relevant to the preferential flow of viscous liquids such as liquid fertilizers in agricultural fields, oil recovery processes, and the intrusion of saline water into the freshwater of coastal aquifers.

Pore-scale Mixing and the Evolution from Anomalous to Normal Hydrodynamic Dispersion

2021 ◽  
Author(s):  
Marco Dentz ◽  
Alexandre Puyguiraud ◽  
Philippe Gouze
Keyword(s):  
Porous Media ◽  
Large Scale ◽  
Molecular Diffusion ◽  
Pore Space ◽  
Breakthrough Curves ◽  
Heterogeneous Porous Media ◽  
Hydrodynamic Dispersion ◽  
Pore Scale ◽  
Sandstone Sample ◽  
Flow Variability

<p>Transport of dissolved substances through porous media is determined by the complexity of the pore space and diffusive mass transfer within and between pores. The interplay of diffusive pore-scale mixing and spatial flow variability are key for the understanding of transport and reaction phenomena in porous media. We study the interplay of pore-scale mixing and network-scale advection through heterogeneous porous media, and its role for the evolution and asymptotic behavior of hydrodynamic dispersion. In a Lagrangian framework, we identify three fundamental mechanisms of pore-scale mixing that determine large scale particle motion: (i) The smoothing of intra-pore velocity contrasts, (ii) the increase of the tortuosity of particle paths, and (iii) the setting of a maximum time for particle transitions. Based on these mechanisms, we derive an upscaled approach that predicts anomalous and normal hydrodynamic dispersion based on the characteristic pore length, Eulerian velocity distribution and Péclet number. The theoretical developments are supported and validated by direct numerical flow and transport simulations in a three-dimensional digitized Berea sandstone sample obtained using X-Ray microtomography. Solute breakthrough curves, are characterized by an intermediate power-law behavior and exponential cut-off, which reflect pore-scale velocity variability and intra-pore solute mixing. Similarly, dispersion evolves from molecular diffusion at early times to asymptotic hydrodynamics dispersion via an intermediate superdiffusive regime. The theory captures the full evolution form anomalous to normal transport behavior at different Péclet numbers as well as the Péclet-dependence of asymptotic dispersion. It sheds light on hydrodynamic dispersion behaviors as a consequence of the interaction between pore-scale mixing and Eulerian flow variability. </p>

scholarly journals Identification of Nanocellulose Retention Characteristics in Porous Media

2018 ◽  
Author(s):  
Reidun C. Aadland ◽  
Carter J. Dziuba ◽  
Ellinor B. Heggset ◽  
Kristin Syverud ◽  
Ole Torsæter ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Media ◽  
Oil Recovery ◽  
Petroleum Industry ◽  
Retention Mechanism ◽  
Bulk Solution ◽  
Permeability Reduction ◽  
Berea Sandstone ◽  
Retention Characteristics ◽  
Series Of Experiments

The application of nanotechnology to the petroleum industry has sparked recent interest to increase oil recovery while reducing environmental impact. Nanocellulose is an emerging nanoparticle that is derived from trees and may provide an environmentally friendly alternative to current enhanced oil recovery (EOR) technologies. However, before nanocellulose can be applied as an EOR technique, further understanding of its transport behavior and retention in porous media is required. The research documented in this paper examines retention mechanisms that occur during nanocellulose transport. In a series of experiments, nanocellulose particles dispersed in brine were injected into sandpacks and Berea sandstone cores. The resulting retention and permeability reduction were measured. The experimental parameters that were varied include sand grain size, nanocellulose type, salinity, and flow rate. Under low salinity conditions, the dominant retention mechanism was adsorption and when salinity was increased, the dominant retention mechanism shifted towards log-jamming. Retention and permeability reduction increased as grain size decreased, which results from increased straining of nanocellulose aggregates. In addition, each type of nanocellulose was found to have significantly different transport properties. The experiments with Berea sandstone cores indicate that some pore volume was inaccessible to the nanocellulose. As a general trend, the larger the size of aggregates in bulk solution, the greater the observed retention and permeability reduction. Salinity was found to be the most important parameter affecting transport. Increased salinity caused additional aggregation, which led to increased straining and filter cake formation. Higher flow rates were found to reduce retention and permeability reduction. Increased velocity was accompanied by an increase in shear which is believed to promote breakdown of nanocellulose aggregates.

Gravity segregation during miscible displacement—re-investigation and re-interpretation

Soil Research ◽  
2007 ◽  
Vol 45 (5) ◽  
pp. 319 ◽  
Author(s):  
D. A. Rose ◽  
F. Abbas
Keyword(s):  
Cross Sections ◽  
Formal Analysis ◽  
Safety Margin ◽  
Breakthrough Curves ◽  
Hydrodynamic Dispersion ◽  
Immiscible Liquids ◽  
Saline Groundwater ◽  
Gravity Segregation ◽  
Dimensional Gravity ◽  
Miscible Liquids

When the liquid residing in a horizontal bed of porous material is displaced by another liquid of different density, the resulting hydrodynamic dispersion is modified by the formation of a tongue of denser liquid undershooting the less dense liquid, a phenomenon known as gravity segregation. An earlier account of gravity segregation contained a substantial error (that of an incorrect frame of reference for flow) and several printing mistakes. In this paper we (i) correct these errors, (ii) extend the analysis to describe the course of breakthrough in beds of rectangular and circular cross-sections, (iii) re-interpret the existing experimental evidence, and (iv) present new experimental results on the vertical and horizontal transport of ionic solutions of different concentrations and densities through inert and reactive porous materials, ballotini, and sepiolite, respectively. The behaviour of immiscible liquids is predicted by the non-dimensional gravity segregation number, β, segregation becoming more extreme as β increases. With miscible liquids, however, breakthrough starts later and ends earlier then predicted for immiscible liquids, mixing by hydrodynamic dispersion moderating the effect of segregation. Breakthrough curves are well fitted by CXTFIT 2.0; apparent coefficients of hydrodynamic dispersion vary much less with pore-water velocity in horizontal than in vertical flow, but retardation factors are not influenced by orientation. Although a formal analysis of the combined effect of gravity segregation and hydrodynamic dispersion was not possible, the statistically significant inverse relation between β and column Peclet number was explained qualitatively. Gravity segregation occurs during the intrusion of saline groundwater into coastal aquifers. The simple theory for immiscible displacement overestimates the actual intrusion that occurs with miscible liquids and so provides an effective safety margin.

Laboratory and field studies of preferential flow dynamics in unsaturated fractured porous media

2021 ◽  
Author(s):  
Florian Rüdiger ◽  
Kim Bartsch ◽  
John R. Nimmo ◽  
Jannes Kordilla
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Preferential Flow ◽  
Flow Dynamics ◽  
Interaction Matrix ◽  
Vertical Flow ◽  
Fracture Networks ◽  
Infiltration Rates

<p>Recharge dynamics within the vadose zone (variable saturation conditions) of consolidated fractured rock formations are an ongoing challenge when it comes to process understanding and predictive modeling. The proper delineation of fast (macropores, fractures, conduits) and slow (matrix) flow components in these systems and their interaction with each other remains a complex puzzle and holds a key to enhance process-based infiltration models.</p><p>We conducted laboratory and field experiments to study infiltration dynamics through porous-fractured systems. Laboratory experiments were carried out with analogue fracture networks on meter scale. Orthogonal networks were created by placing equally sized blocks with a constant gap between to glass plates, which were mount by metal clamps. Vertical flow through different network configurations (apertures, intersection types, topology, flow rates) was studied for (1) porous media (sandstone) and (2) non-porous media (glass) to delineate the control of network features on flow dynamics, as well as the effect of fracture-matrix interaction. Matrix imbibition was found to strongly control the preferential flow velocity during flow path evolution. Higher infiltration rates lead to more by-pass at fracture intersections, whereas low infiltration rates favor flow partitioning into horizontal fractures. Vertical flow progression within the non-porous network is significantly faster due to the lack of imbibition. Semi-analytical tools, such as transfer functions, and source-responsive dual-domain models are tested to reproduce the experimental data and to incorporate key features of fracture networks in future modeling approaches. We additionally obtained experimental data from infiltration dynamics at porous-fractured field sites on meter scale to compare them to the well-controlled laboratory experiments and to evaluate the applicability of the results to actual field processes.</p>

Limitations in the use of electrical conductivity to monitor the behaviour of soil solution

Soil Research ◽  
2006 ◽  
Vol 44 (7) ◽  
pp. 695 ◽  
Author(s):  
D. A. Rose ◽  
F. Abbas ◽  
M. A. Adey
Keyword(s):  
Electrical Conductivity ◽  
Solution Concentration ◽  
Solute Concentration ◽  
Breakthrough Curves ◽  
Time Domain Reflectometry ◽  
Solid Particles ◽  
Bulk Solution ◽  
Hydrodynamic Dispersion ◽  
Wide Range ◽  
The Individual

Solutions of KBr and K2SO4 of various concentrations were separately displaced by deionised water through 2 contrasting saturated materials, inert solid particles (glass ballotini), and a reactive but non-swelling aggregated clay mineral (sepiolite) over a wide range of flow rates. The concentration of the individual ions in the effluent was analysed (Br– and K+ with ion-specific electrodes, SO42+ by ion chromatography) and that of bulk solution was measured by electrical conductivity (EC). For each displacement, the individual breakthrough curves (BTCs) for the anion, the cation, and the bulk solution were optimised by CXTFIT 2.0. In ballotini, the BTCs of the anion, cation, and solution were always congruent, the retardation factors did not differ significantly from unity, and the coefficients of hydrodynamic dispersion were identical. For sepiolite, the ions were separated; the bulk solution eluted faster than the cation, slower than the anions. Retardation factors were always less than unity for the anions, greater than unity for the cation, and close to but less than unity for the bulk solution, and became more extreme as the concentration of solute decreased. Dispersion coefficients were, however, unaffected by type of solute, concentration range, or particular ion/EC. The separation of ions means that the composition as well as the concentration of a solution changes continuously during flow through a reactive soil. Estimates of solution concentration from measurements of EC may thus fail to characterise adequately the movement of the individual components of the solution in such materials. This has implications for the interpretation of any leachate monitoring in reactive soils by methods based on the measurement of EC, such as time-domain reflectometry.

Partitioning of preferential flows in fracture networks: Smoothed Particle Dynamics simulations and analytical modeling of infiltration dynamics

2020 ◽  
Author(s):  
Jannes Kordilla ◽  
Marco Dentz ◽  
Alexandre Tartakovsky
Keyword(s):  
Porous Media ◽  
Preferential Flow ◽  
Contact Angles ◽  
Single Fracture ◽  
Vertical Flow ◽  
Fracture Networks ◽  
Diffuse Infiltration ◽  
Flow Component ◽  
Fracture Intersection ◽  
Smoothed Particle

<p>Recharge estimation in fractured-porous aquifers is an essential tool for proper water management and assessment of vulnerability. As opposed to diffuse infiltration, often encountered in consolidated and unconsolidated porous media, the infiltration dynamics in the unsaturated zone of fractured-porous media and karst aquifers often exhibit a rapid, gravity-driven flow component along preferential flow paths such as fractures, fracture networks, faults and fault zones. The partitioning into two hydraulically contrasting domains commonly leads to a breakdown of classical volume-effective flow equations employed in many FD or FEM modeling approaches which only consider the capillarity of the medium. Even in the presence of a porous matrix, preferential pathways along fractures have been shown to sustain flow percolation under equilibrium and non-equilibrium conditions. In order to properly capture the flow physics, various components have to be considered such as static and dynamic contact angles, surface tension, free-surface (multi-phase) interface dynamics, dynamic switching of flow modes (between droplets, rivulets, films) and associated formation of singularities in the case of merging or snapping flow. Here we study the process of vertical infiltration and partitioning at a single fracture intersection into a horizontal and vertical flow component. Via parallelized Smoothed Particle Hydrodynamics simulations we demonstrate how flow is first channeled into the horizontal fracture and then transitions into a Washburn-type inflow when pressure conditions are met and a connection to the next vertical flow path is established. We further proceed to capture this process with an analytical approach and finally demonstrate how to obtain a process-based transfer function to upscale this process to arbitrary fracture geometries and fracture cascades.</p>

scholarly journals Identification of Nanocellulose Retention Characteristics in Porous Media

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 547 ◽  
Author(s):  
Reidun Aadland ◽  
Carter Dziuba ◽  
Ellinor Heggset ◽  
Kristin Syverud ◽  
Ole Torsæter ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Media ◽  
Oil Recovery ◽  
Petroleum Industry ◽  
Good Alternative ◽  
Retention Mechanism ◽  
Bulk Solution ◽  
Permeability Reduction ◽  
Berea Sandstone ◽  
Retention Characteristics

The application of nanotechnology to the petroleum industry has sparked recent interest in increasing oil recovery, while reducing environmental impact. Nanocellulose is an emerging nanoparticle that is derived from trees or waste stream from wood and fiber industries. Thus, it is taken from a renewable and sustainable source, and could therefore serve as a good alternative to current Enhanced Oil Recovery (EOR) technologies. However, before nanocellulose can be applied as an EOR technique, further understanding of its transport behavior and retention in porous media is required. The research documented in this paper examines retention mechanisms that occur during nanocellulose transport. In a series of experiments, nanocellulose particles dispersed in brine were injected into sandpacks and Berea sandstone cores. The resulting retention and permeability reduction were measured. The experimental parameters that were varied include sand grain size, nanocellulose type, salinity, and flow rate. Under low salinity conditions, the dominant retention mechanism was adsorption and when salinity was increased, the dominant retention mechanism shifted towards log-jamming. Retention and permeability reduction increased as grain size decreased, which results from increased straining of nanocellulose aggregates. In addition, each type of nanocellulose was found to have significantly different transport properties. Experiments with Berea sandstone cores indicate that some pore volume was inaccessible to the nanocellulose. As a general trend, the larger the size of aggregates in bulk solution, the greater the observed retention and permeability reduction. Salinity was found to be the most important parameter affecting transport. Increased salinity caused additional aggregation, which led to increased straining and filter cake formation. Higher flow rates were found to reduce retention and permeability reduction. Increased velocity was accompanied by an increase in shear, which is believed to promote breakdown of nanocellulose aggregates.

Simulation of Viscous Fingering Phenomenon Using CFD Tools

2014 ◽  
Author(s):  
Diana González ◽  
Miguel Asuaje
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Preferential Flow ◽  
Viscous Fingering ◽  
Analytical Models ◽  
Water Mixture ◽  
Ansys Fluent ◽  
Two Fluids ◽  
World Energy ◽  
Flow Through

The world energy crisis requires better and better oil production processes. Oil is stored inside a porous medium in reservoirs several kilometers below the earth’s surface. Over the years, the study and understanding of the physics and fluid phenomena occurring within the porous media have been of great interest. A very common phenomenon within the porous media that has significant impact on production is what is known as viscous fingering. Viscous fingering is an instability that occurs at the interface between two fluids of different viscosity, under certain conditions of speed and pressure, this phenomenon results in undesired production of water together with oil. Experiments and analytical models, trying to reproduce and predict the conditions under which the fingering appears, have extensively studied this phenomenon. The aim of this study is to simulate the phenomenon of viscous fingering using computational fluid dynamics tools. A 2D CFD model of an Oil-Water mixture inside a porous medium using commercial software ANSYS FLUENT v.14 was created. In this model, water enters at a rate of 0.15cm/s to an oil-filled domain. Water drives the oil and forms finger-shaped patterns. It was possible to represent the phenomena using CFD tools. Results show a similar behaviour to that obtained by Brock et al (1991): as fingers grew, they spread transversely, split into smaller fingers, coalesced and blocked the growth of other fingers. It was also observed that water fingers have greater velocity, showing its preferential flow through the formed channels and thus leading to inefficient oil extraction.

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