Eirik Grude Flekkøy

Eirik Grude Flekkøy
University of Oslo · Department of Physics

About

136
Publications
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3,241
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Publications

Publications (136)
Article
We study the effects of connectivity enhancement due to film flow phenomena on the drainage of an artificial porous medium and the relative influence of gravity for such effects. The medium is initially fully saturated with a liquid (wetting phase), which is displaced by air (nonwetting phase). Our setup allows us to directly visualize the dynamics...
Article
Aligned finger structures, with a characteristic width, emerge during the slow drainage of a liquid-granular mixture in a tilted Hele-Shaw cell. A transition from vertical to horizontal alignment of the finger structures is observed as the tilting angle and the granular density are varied. An analytical model is presented, demonstrating that the al...
Article
Full-text available
The macroscopic laws controlling the advection and diffusion of solute at the scale of the porous continuum are derived in a general manner that does not place limitations on the geometry and time evolution of the pore space. Special focus is given to the definition and symmetry of the dispersion tensor that is controlling how a solute plume spread...
Article
Onsager reciprocity relations derive from the fundamental time reversibility of the underlying microscopic equations of motion. This gives rise to a large set of symmetric cross-coupling phenomena. We here demonstrate that different reciprocity relations may arise from the notion of mesoscopic time reversibility, i.e., reversibility of intrinsicall...
Article
Acoustic signal localization is a complex problem with a wide range of industrial and academic applications. Herein, we propose a localization method based on energy attenuation and inverted source amplitude comparison (termed estimated source energy homogeneity, or ESEH). This inversion is tested on both synthetic (numerical) data using a Lamb wav...
Article
Full-text available
We study experimentally the flow and patterning of a granular suspension displaced by air inside a narrow tube. The invading air-liquid interface accumulates a plug of granular material that clogs the tube due to friction with the confining walls. The gas percolates through the static plug once the gas pressure exceeds the pore capillary entry pres...
Article
Aligned finger structures, with a characteristic width, emerges during the slow drainage of a liquid/granular mixture in a tilted Hele-Shaw cell. A transition from vertical to horizontal alignment of the finger structures is observed as the tilting angle and the granular density are varied. An analytical model is presented, demonstrating that the a...
Article
Full-text available
We experimentally investigate the rotation of plate shaped aggregates of clay mineral particles immersed in silicone oil. The rotation is induced by an external electric field. The rotation time is measured as a function of the following parameters: electric field strength, the plate geometry (length and width) and the dielectric properties of the...
Article
We study the formation of viscous fingering and fracturing patterns that occur when air at constant overpressure invades a circular Hele-Shaw cell containing a liquid-saturated deformable porous medium—i.e., during the flow of two non-miscible fluids in a confined granular medium at high enough rate to deform it. The resulting patterns are characte...
Article
The characterization and understanding of rock deformation processes due to fluid flow is a challenging problem with numerous applications. The signature of this problem can be found in Earth Science and Physics, notably with applications in natural hazard understanding, mitigation or forecast (e.g., earthquakes, landslides with hydrological contro...
Article
Experiments on confined two-phase flow systems, involving air and a dense suspension, have revealed a diverse set of flow morphologies. As the air displaces the suspension, the beads that make up the suspension can accumulate along the interface. The dynamics can generate "frictional fingers" of air coated by densely packed grains. We present here...
Article
We provided a derivation of the Cole-Cole relation for the conductivity of fluid-saturated, mineralized rocks. This was done via an upscaling procedure that assumed that each element in the system was itself described by the Cole-Cole relation. The purpose of this was to give the parameters of the Cole-Cole relation, most notably the exponent and t...
Article
The Differentially Normalized Method of Electrical Prospecting (DNME) was initially developed by the Russian company SGRPC and deployed commercially already in 2002. It uses a towed controlled electromagnetic source and a towed receiver cable for hydrocarbon detection, by recording and analyzing the Induced Polarization (IP) effects at relatively s...
Article
Full-text available
We present an experimental study of two-phase flow in a quasi-two-dimensional porous medium. The two phases, a water-glycerol solution and a commercial food grade rapeseed/canola oil, having an oil to water-glycerol viscosity ratio M = 1.3, are injected simultaneously into a Hele-Shaw cell with a mono-layer of randomly distributed glass beads. The...
Article
Fluid-saturated granular and porous layers can undergo liquefaction and lose their shear resistance when subjected to shear forcing. In geosystems, such a process can lead to severe natural hazards of soil liquefaction, accelerating slope failure, and large earthquakes. Terzaghi's principle of effective stress predicts that liquefaction occurs when...
Article
Full-text available
It is well known that the transient behavior during drainage or imbibition in multiphase flow in porous media strongly depends on the history and initial condition of the system. However, when the steady-state regime is reached and both drainage and imbibition take place at the pore level, the influence of the evolution history and initial preparat...
Article
We found a physical interpretation of the Cole-Cole relation for the conductivity of fluid-saturated, mineralized rocks. The first step was to rederive a diffusive version of the Cole-Cole relation from a pore-scale description that couples diffusion and electrochemistry in a simplified way. We wanted to give the parameters of the Cole-Cole relatio...
Article
The characteristics of the hydro-thermal flow which occurs when a cold fluid is injected into a hot fractured bedrock depend on the morphology of the fracture. We consider a sharp triangular asperity, invariant in one direction, perturbing an otherwise flat fracture. We investigate its influence on the macroscopic hydraulic transmissivity and heat...
Article
Full-text available
The electromagnetic method of Differentially Normalized Method of Electric prospecting is based on the detection of two independent hydrocarbon indicators, namely resistivity- and induced polarization (IP) contrasts. The combination of the two gives a characteristic signature of hydrocarbon presence. The geological foundation of the method is the f...
Article
Full-text available
It is well known that the transient behavior during drainage or imbibition in multiphase flow in porous media strongly depends on the history and initial condition of the system. However, when the steady-state regime is reached and both drainage and imbibition take place at the pore level, the influence of the evolution history and initial preparat...
Conference Paper
EGU 2013 Abstract - Stylolites as well as fractures are reported as major conduits in geological media (1, 2). The flow circulation has a strong influence on hydro-mecanico-chemical processes, in particular on crystallization and dissolution (3, 4). For instance hydrothermal ore deposits are frequently located in stylolites and fractures at depth....
Conference Paper
EGU 2013 - Abstract The porous medium that we consider is a fracture with impermeable walls that have a complex topography. Our study aims at addressing the heat and mass transport which occurs during the injection of cold water into a fracture, initially filled with warm water and embedded in a warm rock. The characterization of such transfers is...
Article
Stress induced by fluid or gases can cause diverse materials to break and fracture. Such hydraulic fractures are a natural and common phenomenon in the field of volcanism and are artificially initiated to enhance the recovery of natural gas and mineral oil by fracturing the reservoir rock with pressurized fluids. A procedure also known as fracking....
Article
Full-text available
Dynamically induced spatial variations of pore pressure and the meaning of Terzhagi's effective stress
Article
Dissipative interactions between grains often lead to instabilities and pattern formation in flows involving granular materials. This is especially so in wet granular flows, where viscous and capillary forces add to the complex dynamics. In a recent study we found an extraordinary diversity in the flow behaviour of wet granular material displaced b...
Article
When seismic waves travel through certain soils, these can lose resistance to shear, and become liquid-like: they display a thixotropic behavior. The buildings and structures lying on them can then subside, or sink partly in the soild, while mud volcanoes are formed around pipes and cracks where the liquefied soil exits. We show how a simple criter...
Article
A transition in hydraulically induced granular displacement patterns is studied by means of discrete numerical molecular dynamics simulations. During this transition the patterns change from fractures and fingers to finely dispersed bubbles. The dynamics of the displacement patterns are studied in a rectangular Hele-Shaw cell filled with a dense bu...
Conference Paper
The response of rotational alignment of lithium fluorohectorite (Li-Fh) to an external electric field has been studied by employing image analysis. Large aggregates consisting of many single clay particles were prepared using a sedimentation technique in order to control both their shapes and sizes. Such aggregates have a layered structure which wa...
Article
Natural electric field variations are measured at the sea bottom over long periods of time by means of stationary, vertical, and horizontal galvanic antennas. We compare the power spectra of the vertical and horizontal field components and the extent to which they may be reduced by standard averaging techniques. Although the raw spectra of the vert...
Article
During the hydraulically induced compaction of a granular layer fracture patterns arise. In numerical simulations we study how these patterns depend on the gas properties as well as on the properties of the porous medium. In particular the relation between the speed of fracture propagation and injection pressure is here studied in detail.
Article
When submillimetric particles are confined in a fluid such that a compact cluster of particles lie above the clear fluid, particles will detach from the lower boundary of the cluster and form an unstable separation front giving rise to growing fingers of falling particles. We study this problem using both experiments and hybrid granular/fluid mecha...
Article
Full-text available
When a compressible gas displaces a granular mixture in a quasi 2D space, friction causes stick slip motion. A localized slip event at the interface allows expansion of the compressed gas and a sudden forward motion of the front. The reservoir volume of gas determines the available elasticity in the system, and thereby the size of the expansion. La...
Article
Here we shall investigate the displacement of wet granular mixtures and deformable porous media by an invading gas. The experiment is straight forward: a mixture of grains and fluid is loaded into the gap between two glass plates, followed by injection of gas at constant rate. As it turns out, the resulting dynamics is far from simple. Several forc...
Article
The characteristics of the hydro-thermal flow which occurs when a cold fluid is injected into a hot fractured bedrock depend on the morphology of the fracture [1]. This was shown under lubrication approximations -- which assume that the fracture morphology varies in a smooth way -- by solving Stokes equation and a bidimensional (integrated over the...
Article
We investigate the formation of fracture of a porous rock due to pressurization of the intersticial fluid. Depending on the viscosity and compressibility of the fluid, of the system size and porous medium geometry, we show that the fluid permetaion can occur through simple permeation, smooth deformation of the matrix, or generation of fractal fluid...
Article
During the hydraulically induced compaction of a granular layer fracture patterns arise. In numerical simulations we study how these patterns depend on the gas properties as well as on the properties of the porous medium. In particular the relation between the speed of fracture propagation and injection pressure is here studied in detail. Durante l...
Article
The natural E-field variations measured at the sea bottom, and the magnitude of the different field components compared in the light of the theory for induction caused by ocean surface waves. At shallow sea depths of 107-122 meters only the vertical component carries an observable effect of ocean waves, whereas the horizontal field is dominated by...
Article
Remarkable shapes and patterns appear in multiphase flow experiments with frictional fluids. Here we explore the rich dynamics, and map the emerging morphologies in a phase diagram.
Article
While pattern-forming processes in simple fluids and suspensions have been studied extensively, and the basic displacement structures, like viscous fingers and fractals in capillary dominated flows, have been identified, the fundamental displacement morphologies in frictional fluids and granular mixtures have not been mapped out. Here we add Coulom...
Article
Layered low permeability rock units, like shales, represent seals or ‘cap-rocks’ in a variety of geological settings. A continuous increase in the fluid pressure gradients across a virtually impermeable rock layer will ultimately lead to hydro-fracturing. Depending on the boundary conditions, such fracturing may lead to the formation of a set of su...
Article
Full-text available
Understanding the electromagnetic noise that reaches the bottom of the sea is of fundamental interest in a range of contexts. In magnetotellurics the natural electromagnetic field variations is used to detect resistive or conductive bodies in the subsurface. Effects of air-sea boundary give different noise spectra in the different E-field component...
Data
This movie shows the displacement dynamics for the two experiments presented in Fig. 2. At low filling fraction f the injected air invades the granular fluid mixture in a creeping fingering fashion, while a transition to stick slip bubble formation is seen at high f. The injection rate and the volume of air contained in the syringe was the same in...
Data
This movie shows examples of the types of displacement dynamics that emerge at different injection rates, starting with stick slip bubbles at low rate (q = 0.03 ml/min), followed by "temporal intermittency" where periods of continuous motion are interrupted by occasional jamming (0.3 ml/min), "Coral" growth (0.1 ml/min) and destabilized viscous fin...
Article
Full-text available
Pattern-forming processes in simple fluids and suspensions have been studied extensively, and the basic displacement structures, similar to viscous fingers and fractals in capillary dominated flows, have been identified. However, the fundamental displacement morphologies in frictional fluids and granular mixtures have not been mapped out. Here we c...
Article
Full-text available
We present here a direct comparison between a slow quasi-two-dimensional pore scale drainage experiment and a two-component 2D lattice Boltzmann simulation. An experimental setup consisting of approximately 10×10 pores is mapped onto the 2D lattice Boltzmann model with the aspiration of reproducing the behavior and dynamics of a slow drainage proce...
Conference Paper
Full-text available
Recent technological advances have made time-lapse EM a real possibility. In particular, EM methods appear to be a promising tool to identify the process of salt water breakthrough between an injection and a production well. We will examine the CSEM method that uses vertical, stationary transmitters and receivers, as has been developed by Petromark...
Article
The effect of an interstitial fluid on the mixing of sedimenting grains is studied numerically in a closed rectangular Hele-Shaw cell. We investigate the impact of the fluid compressibility and fluid viscosity on the dynamics and structures of the granular Rayleigh-Taylor instability. First we discuss the effect of the fluid compressibility on the...
Article
Full-text available
We present a numerical study of the statistical behavior of a two-phase flow in a two-dimensional porous medium subjected to an oscillatory acceleration transverse to the overall direction of flow. A viscous nonwetting fluid is injected into a porous medium filled with a more viscous wetting fluid. During the whole process sinusoidal oscillations o...
Article
We analyze the granular Rayleigh-Taylor instability of densely packed grains immersed in a compressible or an incompressible fluid using numerical simulations and two types of experiments. The simulations are based on a two-dimensional (2D) molecular dynamics model and the experiments have been carried out in systems of grains immersed in water/gly...
Conference Paper
Summary Underwater measurements of electric fields are a key component in most methods for marine hydrocarbon exploration based on electro-magnetism. Often these fields are very weak and their measurements highly challenging. We discuss the physics of a selection of the relevant noise sources in marine EM measurements and the technology designed to...
Article
We study various types of biphasic flows in quasi-two-dimensional transparent porous models. These flows imply a viscous wetting fluid, and a lowly viscous one. The models are transparent, allowing the displacement process and structure to be monitored in space and time. Three different aspects will be presented: 1. In stationary biphasic flows, we...
Article
The size scaling behavior of the granular Rayleigh-Taylor instability [J. L. Vinningland, Phys. Rev. Lett. 99, 048001 (2007)] is investigated experimentally, numerically, and theoretically. An upper layer of grains displaces a lower gap of air by organizing into dense fingers of falling grains separated by rising bubbles of air. The dependence of t...
Article
Full-text available
The effects of seismic stimulation on the flow of two immiscible fluids in an elastic synthetic porous medium is experimentally investigated. A wetting fluid is slowly evacuated from the medium, while a pressure oscillation is applied on the injected non- wetting fluid. The amplitude and frequency of the pressure oscillations as well as the evacuat...
Conference Paper
Full-text available
An offshore technique time domain EM method that uses vertical, transmitters and receivers is studied. We look at three different aspects of this method: the effect of induced polarization, the sensitivity to a given target and finally edge detection of a reservoir. A case study from the Troll gas field is presented. Measurements from different off...
Article
We report on experimental studies of steady-state two-phase flow in a quasi-two-dimensional porous medium. The wetting and the nonwetting phases are injected simultaneously from alternating inlet points into a Hele-Shaw cell containing one layer of randomly distributed glass beads, initially saturated with wetting fluid. The high viscous wetting ph...
Conference Paper
A branching labyrinth of granular material emerges when a confined granular fluid system is slowly drained. From a series of experiments, simulations and theoretical modeling, we explain the mechanism for the pattern formation in terms of the forces involved. We further show that the granular fluid system undergoes a series of transitions whereby n...
Article
Random labyrinthine patterns have been shown to emerge during slow drainage of granular‐fluid systems in two‐dimensional confinement. We investigate this process under the influence of a gravitational field; that is to say in a tilted system. The isotropy of the labyrinthine pattern is broken. Instead the system is drained from one side, and a fron...
Conference Paper
An offshore, time-domain CSEM (controlled source electromagnetic) technology using vertical transmitters and receivers is presented. The vertical electric field is sensitive to deep resistive layers. A square pulse with an alternating polarity followed by
Article
Full-text available
We present and discuss the properties of a time-domain CSEM (controlled source electromagnetic) technology that utilizes vertically oriented transmitters and receiver antennas. The data are recorded in transient mode, wherein voltage time-series are recorded after transmitter switch-off. A square pulse with an alternating polarity is followed by a...
Article
We present experimental systems where we inject a fluid at high pressure in a poorly cohesive porous material saturated with the same fluid. This fluid is either a highly compressible gas (air), or an almost incompressible and viscous fluid (oil), in an otherwise identical porous matrix. We compare both situations. These porous materials are design...
Article
We aim to model hydro-thermal coupling for fluid flowing inside a rough fracture in a rock at a temperature that differs from that of the fluid. In particular, we wish to model the fully three-dimensional flow in the well-developed topography of fracture boundaries, i.e. we wish to go beyond the classical lubrication limit. Lattice-Boltzmann method...
Article
Full-text available
We study experimentally the case of steady-state simultaneous two-phase flow in a quasi-two-dimensional porous media. The dynamics is dominated by the interplay between a viscous pressure field from the wetting fluid and bubble transport of a less viscous, nonwetting phase. In contrast with more studied displacement front systems, steady-state flow...
Conference Paper
Full-text available
We present and discuss the properties of a time-domain CSEM (Controlled Source ElectroMagnetic) technology that utilizes vertically oriented transmitters and receiver antennas. The data are recorded in transient mode, wherein voltage time-series are recorded after transmitter switchoff. A square pulse with an alternating polarity is followed by a s...
Conference Paper
Experiments on granular-fluid systems in confined geometries have been shown to produce labyrinth patterns. This is the case when the fluid from a particle/fluid dispersion in a Hele-Shaw cell is slowly withdrawn, resembling a drying process. Based on a model of capillary and friction forces, we present a, simulator that reproduces the experimental...
Chapter
We present a new pattern formation process where labyrinthine structures emerge during slow drainage of a confined granular-fluid mixture. Capillary and frictional forces govern the process, and the resulting pattern has a characteristic wavelength that is a function of both the initial volume fraction of granular material in the mixture, and also...
Chapter
Full-text available
A granular instability driven by gravity is studied experimentally and numerically. The instability arises as grains fall in a closed Hele-Shaw cell where a layer of dense granular material is positioned above a layer of air. The initially flat front defined by the grains subsequently develops into a pattern of falling granular fingers separated by...
Article
Full-text available
We compare quantitatively two experimental situations concerning injection of a miscible fluid into an initially jammed granular medium saturated with the same fluid, confined in a Hele-Shaw cell. The two experiments are identical, apart from the interstitial and injected fluid, which is in one case air injected into a dry granular packing, and in...
Article
We study experimentally the injection of a fluid into a loosely consolidated granular media confined a in quasi two dimensional linear cell geometry, initially close to the jamming transition. In this miscible case of an interstitial fluid flow in a deformable porous phase, the assembly of solid grains can behave as a conducting porous matrix, or f...
Article
Saucer-shaped intrusions are fundamental intrusion geometries in sedimentary basins, resulting from the intrusion of either magma or fluidized sand. Previous studies have suggested that such saucer-shaped intrusions result from the mechanical interaction between a growing horizontal fracture and the deforming overburden due to the near free surface...