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9 results found

Zacharoudiou I, Boek ES, Crawshaw J, 2020, Pore-Scale Modeling of Drainage Displacement Patterns in Association With Geological Sequestration of CO2, WATER RESOURCES RESEARCH, Vol: 56, ISSN: 0043-1397

Journal article

Alpak FO, Berg S, Zacharoudiou I, 2018, Prediction of fluid topology and relative permeability in imbibition in sandstone rock by direct numerical simulation, ADVANCES IN WATER RESOURCES, Vol: 122, Pages: 49-59, ISSN: 0309-1708

Journal article

Zacharoudiou I, Boek E, Crawshaw J, 2018, The impact of drainage displacement patterns and Haines jumps on CO2 storage efficiency, Scientific Reports, Vol: 8, ISSN: 2045-2322

Injection of CO2 deep underground into porous rocks, such as saline aquifers, appears to be a promising tool for reducing CO2 emissions and the consequent climate change. During this process CO2 displaces brine from individual pores and the sequence in which this happens determines the efficiency with which the rock is filled with CO2 at the large scale. At the pore scale, displacements are controlled by the balance of capillary, viscous and inertial forces. We simulate this process by a numerical technique, multi-GPU Lattice Boltzmann, using X-ray images of the rock pores. The simulations show the three types of fluid displacement patterns, at the larger scale, that have been previously observed in both experiments and simulations: viscous fingering, capillary fingering and stable displacement. Here we examine the impact of the patterns on storage efficiency and then focus on slow flows, where displacements at the pore scale typically happen by sudden jumps in the position of the interface between brine and CO2, Haines jumps. During these jumps, the fluid in surrounding pores can rearrange in a way that prevent later displacements in nearby pores, potentially reducing the efficiency with which the CO2 fills the total available volume in the rock.

Journal article

Zacharoudiou I, Chapman E, Boek E, Crawshaw Jet al., 2017, Pore-filling events in single junction micro-models with corresponding lattice Boltzmann simulations, Journal of Fluid Mechanics, Vol: 824, Pages: 550-573, ISSN: 0022-1120

The aim of this work is to better understand fluid displacement mechanisms at the pore scale in relation to capillary-filling rules. Using specifically designed micro-models we investigate the role of pore body shape on fluid displacement during drainage and imbibition via quasi-static and spontaneous experiments at ambient conditions. The experimental results are directly compared to lattice Boltzmann (LB) simulations. The critical pore-filling pressures for the quasi-static experiments agree well with those predicted by the Young–Laplace equation and follow the expected filling events. However, the spontaneous imbibition experimental results differ from those predicted by the Young–Laplace equation; instead of entering the narrowest available downstream throat the wetting phase enters an adjacent throat first. Thus, pore geometry plays a vital role as it becomes the main deciding factor in the displacement pathways. Current pore network models used to predict displacement at the field scale may need to be revised as they currently use the filling rules proposed by Lenormand et al. (J. Fluid Mech., vol. 135, 1983, pp. 337–353). Energy balance arguments are particularly insightful in understanding the aspects affecting capillary-filling rules. Moreover, simulation results on spontaneous imbibition, in excellent agreement with theoretical predictions, reveal that the capillary number itself is not sufficient to characterise the two phase flow. The Ohnesorge number, which gives the relative importance of viscous forces over inertial and capillary forces, is required to fully describe the fluid flow, along with the viscosity ratio.

Journal article

Boek ES, Zacharoudiou I, Gray F, Shah SM, Crawshaw JP, Yang Jet al., 2017, Multiphase-Flow and Reactive-Transport Validation Studies at the Pore Scale by Use of Lattice Boltzmann Computer Simulations, SPE Annual Technical Conference and Exhibition, Publisher: SOC PETROLEUM ENG, Pages: 940-949, ISSN: 1086-055X

Conference paper

Zacharoudiou I, Boek E, 2016, Capillary filling and Haines jump dynamics using free energy LatticeBoltzmann simulations, Advances in Water Resources, Vol: 92, Pages: 56-43, ISSN: 0309-1708

We investigate numerically the dynamics of capillary filling and Haines jump events using free energy Lattice Boltzmann (LB) simulations. Both processes are potentially important multi-phase pore-scale flow processes for geological CO2 sequestration and oil recovery. We first focus on capillary filling and demonstrate that the numerical method can capture the correct dynamics in the limit of long times for both high and low viscosity ratios, i.e. the method gives the correct scaling for the length of the penetrating fluid column as a function of time. Examining further the early times of capillary filling, three consecutive length vs. time regimes have been observed, in agreement with available experimental work in the literature. In addition, we carry out simulations of Haines jump events in idealised and realistic rock pore geometries. We observe that the Haines jump events are cooperative, non-local and associated with both drainage and imbibition dynamics. Our observations show that the pore filling dynamics is controlled by the Ohnesorge number, associated with the balance between viscous forces and inertial / surface tension forces. Using this concept, we are able to identify the type of pore filling dynamics that will occur.

Journal article

Boek ES, Zacharoudiou L, Gray F, Shah SM, Crawshaw JP, Yang Jet al., 2014, Multiphase flow and reactive transport at the pore scale using lattice- Boltzmann computer simulations, Pages: 4746-4757

We describe the recent development of lattice-Boltzmann (LB) and particle tracing computer simulations to study flow and reactive transport in porous media. First, we have extended our codes to measure both flow and solute transport from LB calculations directly on pore space images obtained from micro-CT scanning. We consider rocks with increasing degree of heterogeneity: a bead pack, Bentheimer sandstone and Portland carbonate. A novel scheme is proposed to predict probability distributions for molecular displacements using the LB method to calculate both the flow field and solute dispersion. We find excellent agreement with PFG-NMR experiments and quantify the degree of heterogeneity by integrating over the stagnant peaks in the propagator distributions. Second, we validate our LB model for multi-phase flow by calculating capillary filling and capillary pressure in model porous media. Then we extend our models to realistic 3D pore space images and observe the calculated capillary pressure curve in Bentheimer sandstone to be in agreement with experiment. A new process based algorithm is introduced to determine the distribution of wetting and non-wetting phases in the pore space, as a starting point for relative permeability calculations. The Bentheimer relative permeability curves for both drainage and imbibtion are found to be in good agreement with experimental data. These LB simulations can be used for the prediction of multi-phase flow properties in pore space images; as potential element of Special Core AnaLysis (SCAL); and for Enhanced Oil Recovery (EOR) operations. Third, we introduce a GPU algorithm for large scale LB calculations, offering greatly enhanced computing performance in comparison with CPU calculations. Finally, we propose a new hybrid method to calculate reactive transport on pore space images. First, we calculate the flow field using LB and initialise tracer particles in the porous medium. Then we carry out particle advection using a 2nd orde

Conference paper

Setu SA, Zacharoudiou I, Davies GJ, Bartolo D, Moulinet S, Louis AA, Yeomans JM, Aarts DGALet al., 2013, Viscous fingering at ultralow interfacial tension, Soft Matter, Vol: 9, Pages: 10599-10605, ISSN: 1744-6848

We experimentally study the viscous fingering instability in a fluid-fluid phase separated colloid-polymer mixture by means oflaser scanning confocal microscopy and microfluidics. We focus on three aspects of the instability. (i) The interface betweenthe two demixed phases has an ultralow surface tension, such that we can address the role of thermal interface fluctuations. (ii)We image the interface in three dimensions allowing us to study the interplay between interface curvature and flow. (iii) Thedisplacing fluid wets all walls completely, in contrast to traditional viscous fingering experiments, in which the displaced fluidwets the walls. We also perform lattice Boltzmann simulations, which help to interpret the experimental observations.

Journal article

Dammone OJ, Zacharoudiou I, Dullens RPA, Yeomans JM, Lettinga MP, Aarts DGALet al., 2012, Confinement Induced Splay-to-Bend Transition of Colloidal Rods, PHYSICAL REVIEW LETTERS, Vol: 109, ISSN: 0031-9007

Journal article

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