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Steffen Berg - One of the best experts on this subject based on the ideXlab platform.
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surfactant variations in porous media localize capillary instabilities during haines jumps
Physical Review Letters, 2018Co-Authors: Yaniv Edery, David A Weitz, Steffen BergAbstract:We use confocal microscopy to measure velocity and interfacial tension between a trapped wetting Phase with a surfactant and a flowing, invading Nonwetting Phase in a porous medium. We relate interfacial tension variations at the fluid-fluid interface to surfactant concentration and show that these variations localize the destabilization of capillary forces and lead to rapid local invasion of the Nonwetting fluid, resulting in a Haines jump. These spatial variations in surfactant concentration are caused by velocity variations at the fluid-fluid interfaces and lead to localization of the Haines jumps even in otherwise very uniform pore structure and pressure conditions. Our results provide new insight into the nature of Haines jumps, one of the most ubiquitous and important instabilities in flow in porous media.
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beyond darcy s law the role of Phase topology and ganglion dynamics for two fluid flow
Physical Review E, 2016Co-Authors: Ryan T Armstrong, James E Mcclure, M Berrill, Steffen Schluter, M Rucker, Steffen BergAbstract:In multiPhase flow in porous media the consistent pore to Darcy scale description of two-fluid flow processes has been a long-standing challenge. Immiscible displacement processes occur at the scale of individual pores. However, the larger scale behavior is described by phenomenological relationships such as relative permeability, which typically uses only fluid saturation as a state variable. As a consequence pore scale properties such as contact angle cannot be directly related to Darcy scale flow parameters. Advanced imaging and computational technologies are closing the gap between the pore and Darcy scale, supporting the development of new theory. We utilize fast x-ray microtomography to observe pore-scale two-fluid configurations during immiscible flow and initialize lattice Boltzmann simulations that demonstrate that the mobilization of disconnected Nonwetting Phase clusters can account for a significant fraction of the total flux. We show that fluid topology can undergo substantial changes during flow at constant saturation, which is one of the underlying causes of hysteretic behavior. Traditional assumptions about fluid configurations are therefore an oversimplification. Our results suggest that the role of fluid connectivity cannot be ignored for multiPhase flow. On the Darcy scale, fluid topology and Phase connectivity are accounted for by interfacial area and Euler characteristic as parameters that are missing from our current models.
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pore scale displacement mechanisms as a source of hysteresis for two Phase flow in porous media
Water Resources Research, 2016Co-Authors: Hansjorg Vogel, Steffen Schluter, Steffen Berg, Ryan T Armstrong, M Rucker, R Hilfer, D WildenschildAbstract:The macroscopic description of the hysteretic behavior of two-Phase flow in porous media remains a challenge. It is not obvious how to represent the underlying pore-scale processes at the Darcy-scale in a consistent way. Darcy-scale thermodynamic models do not completely eliminate hysteresis and our findings indicate that the shape of displacement fronts is an additional source of hysteresis that has not been considered before. This is a shortcoming because effective process behavior such as trapping efficiency of CO2 or oil production during water flooding are directly linked to pore-scale displacement mechanisms with very different front shape such as capillary fingering, flat frontal displacement, or cluster growth. Here we introduce fluid topology, expressed by the Euler characteristic of the Nonwetting Phase (χn), as a shape measure of displacement fronts. Using two high-quality data sets obtained by fast X-ray tomography, we show that χn is hysteretic between drainage and imbibition and characteristic for the underlying displacement pattern. In a more physical sense, the Euler characteristic can be interpreted as a parameter describing local fluid connectedness. It may provide the closing link between a topological characterization and macroscopic formulations of two-Phase immiscible displacement in porous rock. Since fast X-ray tomography is currently becoming a mature technique, we expect a significant growth in high-quality data sets of real time fluid displacement processes in the future. The novel measures of fluid topology presented here have the potential to become standard metrics needed to fully explore them.
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from connected pathway flow to ganglion dynamics
Geophysical Research Letters, 2015Co-Authors: Steffen Berg, A Georgiadis, Ryan T Armstrong, H Ott, M Rucker, Alexander G Schwing, R Neiteler, N Brussee, A MakuratAbstract:During imbibition, initially connected oil is displaced until it is trapped as immobile clusters. While initial and final states have been well described before, here we image the dynamic transient process in a sandstone rock using fast synchrotron-based X-ray computed microtomography. Wetting film swelling and subsequent snap off, at unusually high saturation, decreases Nonwetting Phase connectivity, which leads to Nonwetting Phase fragmentation into mobile ganglia, i.e., ganglion dynamics regime. We find that in addition to pressure-driven connected pathway flow, mass transfer in the oil Phase also occurs by a sequence of correlated breakup and coalescence processes. For example, meniscus oscillations caused by snap-off events trigger coalescence of adjacent clusters. The ganglion dynamics occurs at the length scale of oil clusters and thus represents an intermediate flow regime between pore and Darcy scale that is so far dismissed in most upscaling attempts.
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modeling the velocity field during haines jumps in porous media
Advances in Water Resources, 2015Co-Authors: Ryan T Armstrong, Nikolay Evseev, Dmitry Koroteev, Steffen BergAbstract:Abstract When Nonwetting fluid displaces wetting fluid in a porous rock many rapid pore-scale displacement events occur. These events are often referred to as Haines jumps and any drainage process in porous media is an ensemble of such events. However, the relevance of Haines jumps for larger scale models is often questioned. A common counter argument is that the high fluid velocities caused by a Haines jump would average-out when a bulk representative volume is considered. In this work, we examine this counter argument in detail and investigate the transient dynamics that occur during a Haines jump. In order to obtain fluid–fluid displacement data in a porous geometry, we use a micromodel system equipped with a high speed camera and couple the results to a pore-scale modeling tool called the Direct HydroDynamic (DHD) simulator. We measure the duration of a Haines jump and the distance over which fluid velocities are influenced because this sets characteristic time and length scales for fluid–fluid displacement. The simulation results are validated against experimental data and then used to explore the influence of interfacial tension and Nonwetting Phase viscosity on the speed of a Haines jump. We find that the speed decreases with increasing Nonwetting Phase viscosity or decreasing interfacial tension; however, for the same capillary number the reduction in speed can differ by an order of magnitude or more depending on whether viscosity is increased or interfacial tension is reduced. Therefore, the results suggest that capillary number alone cannot explain pore-scale displacement. One reason for this is that the interfacial and viscous forces associated with fluid–fluid displacement act over different length scales, which are not accounted for in the pore-scale definition of capillary number. We also find by analyzing different pore morphologies that the characteristic time scale of a Haines jump is dependent on the spatial configuration of fluid prior to an event. Simulation results are then used to measure the velocity field surrounding a Haines jump and thus, measure the zone of influence, which extends over a distance greater than a single pore. Overall, we find that the time and length scales of a Haines jump are inversely proportional, which is important to consider when calculating the spatial and temporal averages of pore-scale parameters during fluid–fluid displacement.
Dorthe Wildenschild - One of the best experts on this subject based on the ideXlab platform.
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a proximity based image processing algorithm for colloid assignment in segmented multiPhase flow datasets
Journal of Microscopy, 2020Co-Authors: Christopher L Brueck, Dorthe WildenschildAbstract:Colloidal transport and deposition are of both environmental and engineering importance. Easier access to x-ray microtomography (XMT) coupled with improved imaging resolution has made XMT a unique and viable tool for visualizing and quantifying these processes. Currently, there is scant information in the literature addressing colloid segmentation and analysis in saturated and unsaturated porous media, in particular related to spatial partitioning of colloids. To support this need, an approach to assign segmented colloidal particles and aggregates to different partitioning classes based on their proximity to different Phases is presented here. The method uses different markers for each attachment site (e.g. wetting-Nonwetting Phase interfaces). An example XMT dataset from a drainage experiment is used to demonstrate the efficacy of the image processing algorithms. Flow conditions, and fluid and colloid properties, can thus be compared to the behaviour of colloids within the porous medium. This algorithm can help elucidate colloidal deposition mechanisms and the importance of different attachment sites, explore the importance of fluid properties, as well as the arrangement and shape of the colloids.
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efficiently engineering pore scale processes the role of force dominance and topology during Nonwetting Phase trapping in porous media
Advances in Water Resources, 2015Co-Authors: Anna L Herring, Linnea Andersson, Steffen Schluter, Adrian Sheppard, Dorthe WildenschildAbstract:Abstract We investigate trapping of a Nonwetting (NW) Phase, air, within Bentheimer sandstone cores during drainage–imbibition flow experiments, as quantified on a three dimensional (3D) pore-scale basis via x-ray computed microtomography (X-ray CMT). The wetting (W) fluid in these experiments was deionized water doped with potassium iodide (1:6 by weight). We interpret these experiments based on the capillary–viscosity–gravity force dominance exhibited by the Bentheimer–air–brine system and compare to a wide range of previous drainage–imbibition experiments in different media and with different fluids. From this analysis, we conclude that viscous and capillary forces dominate in the Bentheimer–air–brine system as well as in the Bentheimer–supercritical CO 2 –brine system. In addition, we further develop the relationship between initial (post-drainage) NW Phase connectivity and residual (post-imbibition) trapped NW Phase saturation, while also taking into account initial NW Phase saturation and imbibition capillary number. We quantify NW Phase connectivity via a topological measure as well as by a statistical percolation metric. These metrics are evaluated for their utility and appropriateness in quantifying NW Phase connectivity within porous media. Here, we find that there is a linear relationship between initial NW Phase connectivity (as quantified by the normalized Euler number, χ ˆ ) and capillary trapping efficiency; for a given imbibition capillary number, capillary trapping efficiency (residual NW Phase saturation normalized by initial NW Phase saturation) can decrease by up to 60% as initial NW Phase connectivity increases from low connectivity ( χ ˆ ≈ 0) to very high connectivity ( χ ˆ ≈ 1). We propose that multiPhase fluid-porous medium systems can be efficiently engineered to achieve a desired residual state (optimal NW Phase saturation) by considering the dominant forces at play in the system along with the impacts of NW Phase topology within the porous media, and we illustrate these concepts by considering supercritical CO 2 sequestration scenarios.
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effect of fluid topology on residual Nonwetting Phase trapping implications for geologic co 2 sequestration
Advances in Water Resources, 2013Co-Authors: Anna L Herring, Linnea Andersson, Adrian Sheppard, Elizabeth J Harper, Brian K Bay, Dorthe WildenschildAbstract:We gratefully acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program (#20100025DR) for this work; as well as the Department of Energy’s Basic Energy Sciences, Geosciences Program via Grant number DE-FG02-11ER16277. The research of Adrian Sheppard is supported by an Australian Research Council Future Fellowship (FT100100470).
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measurement and prediction of the relationship between capillary pressure saturation and interfacial area in a napl water glass bead system
Water Resources Research, 2010Co-Authors: Mark L Porter, Dorthe Wildenschild, Gavin P Grant, Jason I GerhardAbstract:(1) In this work, the constitutive relationship between capillary pressure (Pc), saturation (Sw), and fluid-fluid interfacial area per volume (IFA) is characterized using computed microtomography for drainage and imbibition experiments consisting of a nonaqueous Phase liquid and water. The experimentally measured relationship was compared to a thermodynamic model that relates the area under the PcSw curve to the total IFA, an, and the capillary-associated IFA, anw. Surfaces were fit to the experimental and modeled PcSwan and PcSwanw data in order to characterize the relationship in three dimensions (3D). For the experimental system, it was shown that the PcSwan relationship does not exhibit hysteresis. The model is found to provide a reasonable approximation of the magnitude of the 3D surfaces for an and anw, with a mean absolute percent error of 26% and 15%, respectively. The relatively high mean absolute percent errors are primarily the result of discrepancies observed at the wetting- and Nonwetting-Phase residual saturation values. Differences in the shapes of the surfaces are noted, particularly in the curvature (arising from the addition of scanning curves and presence of anSw hysteresis in the predicted results) and endpoints (particularly the inherent nature of thermodynamic models to predict significant anw associated with residual Nonwetting-Phase saturation). Overall, the thermodynamic model is shown to be a practical, inexpensive tool for predicting the PcSwan and PcSwanw surfaces from PcSw data. Citation: Porter, M. L., D. Wildenschild, G. Grant, and J. I. Gerhard (2010), Measurement and prediction of the relationship between capillary pressure, saturation, and interfacial area in a NAPL-water-glass bead system, Water Resour. Res., 46, W08512,
Mohsen Masihi - One of the best experts on this subject based on the ideXlab platform.
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experimental study of some important factors on Nonwetting Phase recovery by cocurrent spontaneous imbibition
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Esmaeil Hamidpour, Abouzar Mirzaeipaiaman, Mohsen Masihi, Behrouz HarimiAbstract:Abstract Spontaneous imbibition, defined as the displacement of Nonwetting Phase by wetting Phase in porous media by action of capillary forces, is important in many applications within earth sciences and in particular in naturally fractured oil and gas reservoirs. Hence, it is critical to investigate the various aspects of this process to correctly model the fractured reservoir behavior. In this study, twenty four experiments were conducted to study the effect of rock properties, lithology of porous medium, brine viscosity and boundary conditions on displacement rate and final recovery by cocurrent spontaneous imbibition (COCSI) in brine-oil systems. The results can be extended to brine-gas systems, as well. The porous media were reservoir sandstone and limestone samples from Iran. Brines with different viscosities (1, 3.3, 7 and 18 cp) were used as the wetting fluids whereas kerosene and liquid paraffin with viscosities of 1.13 and 28 cp were the Nonwetting fluids. Two boundary conditions were simulated; one-dimensional COCSI where the lateral surfaces of vertically positioned core samples were sealed and brine and oil were covering, respectively bottom and top surfaces of the cores; and multi-dimensional COCSI where the lower and upper halves of core samples were in contact with, respectively brine and oil. The presented experiments provide a data base to verify the future analytical and numerical models. The obtained data was further used to check the hypothesis of linear relationship between the recovery by COCSI and square root of time in the systems where both displacing and displaced fluids were viscous. The viscosity ratio, defined as the ratio of brine viscosity to oil viscosity, ranged from 0.04 to 15.93.
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scaling of recovery by cocurrent spontaneous imbibition in fractured petroleum reservoirs
Energy technology, 2014Co-Authors: Abouzar Mirzaeipaiaman, Mohsen MasihiAbstract:Cocurrent spontaneous imbibition (COCSI) of an aqueous Phase into matrix blocks arising from capillary forces is an important mechanism for petroleum recovery from fractured petroleum reservoirs. In this work, the analytical solution to the COCSI is used to develop the appropriate scaling equations. In particular, the backflow production of the Nonwetting Phase at the inlet face is considered. The resulting scaling equations incorporate all factors that influence the process and are found in terms of the Darcy number (Da) and capillary number, (Ca). The proposed scaling equations are validated against the published experimental data from the literature.
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scaling equations for oil gas recovery from fractured porous media by counter current spontaneous imbibition from development to application
Energy & Fuels, 2013Co-Authors: Abouzar Mirzaeipaiaman, Mohsen MasihiAbstract:Spontaneous imbibition, the capillary-driven process of displacing the Nonwetting Phase by the wetting Phase in porous media, is of great importance in oil/gas recovery from matrix blocks of fractured reservoirs. The question of how properly scaling up the recovery by counter-current spontaneous imbibition has been the subject of extensive research over decades, and numerous scaling equations have been proposed. As a convention, the scaling equations are usually defined analytically by relating the early time squared recovery to squared pore volume. We show this convention does not apply to common scaling practices and, if used, causes nontrivial scatter in the scaling plots. We explain that for three common scaling practices, where the recovery is normalized by (1) final recovery, (2) pore volume, or (3) initial oil/gas in place, this convention should be redefined accordingly. The main contribution is to emphasize that during the development of any scaling equation, its consistency with common applicati...
Abouzar Mirzaeipaiaman - One of the best experts on this subject based on the ideXlab platform.
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experimental study of some important factors on Nonwetting Phase recovery by cocurrent spontaneous imbibition
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Esmaeil Hamidpour, Abouzar Mirzaeipaiaman, Mohsen Masihi, Behrouz HarimiAbstract:Abstract Spontaneous imbibition, defined as the displacement of Nonwetting Phase by wetting Phase in porous media by action of capillary forces, is important in many applications within earth sciences and in particular in naturally fractured oil and gas reservoirs. Hence, it is critical to investigate the various aspects of this process to correctly model the fractured reservoir behavior. In this study, twenty four experiments were conducted to study the effect of rock properties, lithology of porous medium, brine viscosity and boundary conditions on displacement rate and final recovery by cocurrent spontaneous imbibition (COCSI) in brine-oil systems. The results can be extended to brine-gas systems, as well. The porous media were reservoir sandstone and limestone samples from Iran. Brines with different viscosities (1, 3.3, 7 and 18 cp) were used as the wetting fluids whereas kerosene and liquid paraffin with viscosities of 1.13 and 28 cp were the Nonwetting fluids. Two boundary conditions were simulated; one-dimensional COCSI where the lateral surfaces of vertically positioned core samples were sealed and brine and oil were covering, respectively bottom and top surfaces of the cores; and multi-dimensional COCSI where the lower and upper halves of core samples were in contact with, respectively brine and oil. The presented experiments provide a data base to verify the future analytical and numerical models. The obtained data was further used to check the hypothesis of linear relationship between the recovery by COCSI and square root of time in the systems where both displacing and displaced fluids were viscous. The viscosity ratio, defined as the ratio of brine viscosity to oil viscosity, ranged from 0.04 to 15.93.
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scaling of recovery by cocurrent spontaneous imbibition in fractured petroleum reservoirs
Energy technology, 2014Co-Authors: Abouzar Mirzaeipaiaman, Mohsen MasihiAbstract:Cocurrent spontaneous imbibition (COCSI) of an aqueous Phase into matrix blocks arising from capillary forces is an important mechanism for petroleum recovery from fractured petroleum reservoirs. In this work, the analytical solution to the COCSI is used to develop the appropriate scaling equations. In particular, the backflow production of the Nonwetting Phase at the inlet face is considered. The resulting scaling equations incorporate all factors that influence the process and are found in terms of the Darcy number (Da) and capillary number, (Ca). The proposed scaling equations are validated against the published experimental data from the literature.
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scaling equations for oil gas recovery from fractured porous media by counter current spontaneous imbibition from development to application
Energy & Fuels, 2013Co-Authors: Abouzar Mirzaeipaiaman, Mohsen MasihiAbstract:Spontaneous imbibition, the capillary-driven process of displacing the Nonwetting Phase by the wetting Phase in porous media, is of great importance in oil/gas recovery from matrix blocks of fractured reservoirs. The question of how properly scaling up the recovery by counter-current spontaneous imbibition has been the subject of extensive research over decades, and numerous scaling equations have been proposed. As a convention, the scaling equations are usually defined analytically by relating the early time squared recovery to squared pore volume. We show this convention does not apply to common scaling practices and, if used, causes nontrivial scatter in the scaling plots. We explain that for three common scaling practices, where the recovery is normalized by (1) final recovery, (2) pore volume, or (3) initial oil/gas in place, this convention should be redefined accordingly. The main contribution is to emphasize that during the development of any scaling equation, its consistency with common applicati...
Steffen Schluter - One of the best experts on this subject based on the ideXlab platform.
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beyond darcy s law the role of Phase topology and ganglion dynamics for two fluid flow
Physical Review E, 2016Co-Authors: Ryan T Armstrong, James E Mcclure, M Berrill, Steffen Schluter, M Rucker, Steffen BergAbstract:In multiPhase flow in porous media the consistent pore to Darcy scale description of two-fluid flow processes has been a long-standing challenge. Immiscible displacement processes occur at the scale of individual pores. However, the larger scale behavior is described by phenomenological relationships such as relative permeability, which typically uses only fluid saturation as a state variable. As a consequence pore scale properties such as contact angle cannot be directly related to Darcy scale flow parameters. Advanced imaging and computational technologies are closing the gap between the pore and Darcy scale, supporting the development of new theory. We utilize fast x-ray microtomography to observe pore-scale two-fluid configurations during immiscible flow and initialize lattice Boltzmann simulations that demonstrate that the mobilization of disconnected Nonwetting Phase clusters can account for a significant fraction of the total flux. We show that fluid topology can undergo substantial changes during flow at constant saturation, which is one of the underlying causes of hysteretic behavior. Traditional assumptions about fluid configurations are therefore an oversimplification. Our results suggest that the role of fluid connectivity cannot be ignored for multiPhase flow. On the Darcy scale, fluid topology and Phase connectivity are accounted for by interfacial area and Euler characteristic as parameters that are missing from our current models.
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pore scale displacement mechanisms as a source of hysteresis for two Phase flow in porous media
Water Resources Research, 2016Co-Authors: Hansjorg Vogel, Steffen Schluter, Steffen Berg, Ryan T Armstrong, M Rucker, R Hilfer, D WildenschildAbstract:The macroscopic description of the hysteretic behavior of two-Phase flow in porous media remains a challenge. It is not obvious how to represent the underlying pore-scale processes at the Darcy-scale in a consistent way. Darcy-scale thermodynamic models do not completely eliminate hysteresis and our findings indicate that the shape of displacement fronts is an additional source of hysteresis that has not been considered before. This is a shortcoming because effective process behavior such as trapping efficiency of CO2 or oil production during water flooding are directly linked to pore-scale displacement mechanisms with very different front shape such as capillary fingering, flat frontal displacement, or cluster growth. Here we introduce fluid topology, expressed by the Euler characteristic of the Nonwetting Phase (χn), as a shape measure of displacement fronts. Using two high-quality data sets obtained by fast X-ray tomography, we show that χn is hysteretic between drainage and imbibition and characteristic for the underlying displacement pattern. In a more physical sense, the Euler characteristic can be interpreted as a parameter describing local fluid connectedness. It may provide the closing link between a topological characterization and macroscopic formulations of two-Phase immiscible displacement in porous rock. Since fast X-ray tomography is currently becoming a mature technique, we expect a significant growth in high-quality data sets of real time fluid displacement processes in the future. The novel measures of fluid topology presented here have the potential to become standard metrics needed to fully explore them.
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efficiently engineering pore scale processes the role of force dominance and topology during Nonwetting Phase trapping in porous media
Advances in Water Resources, 2015Co-Authors: Anna L Herring, Linnea Andersson, Steffen Schluter, Adrian Sheppard, Dorthe WildenschildAbstract:Abstract We investigate trapping of a Nonwetting (NW) Phase, air, within Bentheimer sandstone cores during drainage–imbibition flow experiments, as quantified on a three dimensional (3D) pore-scale basis via x-ray computed microtomography (X-ray CMT). The wetting (W) fluid in these experiments was deionized water doped with potassium iodide (1:6 by weight). We interpret these experiments based on the capillary–viscosity–gravity force dominance exhibited by the Bentheimer–air–brine system and compare to a wide range of previous drainage–imbibition experiments in different media and with different fluids. From this analysis, we conclude that viscous and capillary forces dominate in the Bentheimer–air–brine system as well as in the Bentheimer–supercritical CO 2 –brine system. In addition, we further develop the relationship between initial (post-drainage) NW Phase connectivity and residual (post-imbibition) trapped NW Phase saturation, while also taking into account initial NW Phase saturation and imbibition capillary number. We quantify NW Phase connectivity via a topological measure as well as by a statistical percolation metric. These metrics are evaluated for their utility and appropriateness in quantifying NW Phase connectivity within porous media. Here, we find that there is a linear relationship between initial NW Phase connectivity (as quantified by the normalized Euler number, χ ˆ ) and capillary trapping efficiency; for a given imbibition capillary number, capillary trapping efficiency (residual NW Phase saturation normalized by initial NW Phase saturation) can decrease by up to 60% as initial NW Phase connectivity increases from low connectivity ( χ ˆ ≈ 0) to very high connectivity ( χ ˆ ≈ 1). We propose that multiPhase fluid-porous medium systems can be efficiently engineered to achieve a desired residual state (optimal NW Phase saturation) by considering the dominant forces at play in the system along with the impacts of NW Phase topology within the porous media, and we illustrate these concepts by considering supercritical CO 2 sequestration scenarios.
