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Martin J. Blunt - One of the best experts on this subject based on the ideXlab platform.
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a study to investigate viscous coupling effects on the hydraulic conductance of fluid layers in two Phase flow at the pore level
Journal of Colloid and Interface Science, 2018Co-Authors: Mosayeb Shams, Martin J. Blunt, Ali Q. Raeini, Branko BijeljicAbstract:Abstract This paper examines the role of momentum transfer across fluid-fluid interfaces in two-Phase flow. A volume-of-fluid finite-volume numerical method is used to solve the Navier-Stokes equations for two-Phase flow at the micro-scale. The model is applied to investigate viscous coupling effects as a function of the viscosity ratio, the wetting Phase Saturation and the wettability, for different fluid configurations in simple pore geometries. It is shown that viscous coupling effects can be significant for certain pore geometries such as oil layers sandwiched between water in the corner of mixed wettability capillaries. A simple parametric model is then presented to estimate general mobility terms as a function of geometric properties and viscosity ratio. Finally, the model is validated by comparison with the mobilities computed using direct numerical simulation.
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visualization and quantification of capillary drainage in the pore space of laminated sandstone by a porous plate method using differential imaging x ray microtomography
Water Resources Research, 2017Co-Authors: Qingyang Lin, Branko Bijeljic, Holger Rieke, Martin J. BluntAbstract:The experimental determination of capillary pressure drainage curves at the pore scale is of vital importance for the mapping of reservoir fluid distribution. To fully characterize capillary drainage in a complex pore space we design a Differential Imaging-based Porous Plate (DIPP) method using X-ray micro-tomography. For an exemplar mm-scale laminated sandstone micro-core with a porous plate, we quantify the displacement from resolvable macro-pores and sub-resolution micro-pores. Nitrogen (N2) was injected as the non-wetting Phase at a constant pressure while the porous plate prevented its escape. The measured porosity and capillary pressure at the imaged Saturations agrees well with Helium measurements and experiments on larger core samples, while providing a pore-scale explanation of the fluid distribution. We observed that the majority of the brine was displaced by N2 in macro-pores at low capillary pressures, followed by a further brine displacement in micro-pores when capillary pressure increases. Furthermore, we were able to discern that brine predominantly remained within the sub-resolution micro-pores, such as regions of fine lamination. The capillary pressure curve for pressures ranging from 0 to 1151 kPa is provided from the image analysis compares well with the conventional porous plate method for a cm-scale core, but was conducted over a period of 10 days rather than up to few months with the conventional porous plate method. Overall, we demonstrate the capability of our method to provide quantitative information on two-Phase Saturation in heterogeneous core samples for a wide range of capillary pressures even at scales smaller than the micro-CT resolution.
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Modelling capillary trapping using finite-volume simulation of two-Phase flow directly on micro-CT images
Advances in Water Resources, 2015Co-Authors: Ali Q. Raeini, Branko Bijeljic, Martin J. BluntAbstract:We study capillary trapping in porous media using direct pore-scale simulation of two-Phase flow on micro-CT images of a Berea sandstone and a sandpack. The trapped non-wetting Phase Saturations are predicted by solving the full Navier–Stokes equations using a volume-of-fluid based finite-volume framework to simulate primary drainage followed by water injection. Using these simulations, we analyse the effects of initial non-wetting-Phase Saturation, capillary number and flow direction on the residual Saturation. The predictions from our numerical method are in agreement with published experimental measurements of capillary trapping curves. This shows that our direct simulation method can be used to elucidate the effect of pore structure and flow pattern of capillary trapping and provides a platform to study the physics of multiPhase flow at the pore scale.
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capillary trapping in sandstones and carbonates dependence on pore structure
Water Resources Research, 2012Co-Authors: Yukie Tanino, Martin J. BluntAbstract:[1] Residual non-wetting Phase Saturation and wetting-Phase permeability were measured in three limestones and four sandstones ranging in porosity from 0.13 to 0.28 and in absolute permeability from 2 × 10−15 to 3 × 10−12 m2. This paper focuses on the residual state established by waterflooding at low capillary number from minimum water Saturation achieved using the porous plate technique, which yields the maximum residual under strongly water-wet conditions. The pore coordination number and pore body-throat aspect ratio of each rock were estimated using pore networks extracted from X-ray microtomography images of the rocks. Residual Saturation decreases with increasing porosity, with no apparent difference in magnitude between the limestones and sandstones at a given porosity. Thus intraparticle/intra-aggregate microporosity does not significantly alter the efficiency of capillary trapping in the rocks considered presently. Residual Saturation broadly decreases as conditions become less favorable for snap-off, i.e., with decreasing pore aspect ratio and increasing coordination number. The measured residual Saturations imply that capillary trapping may be an effective mechanism for storing carbon dioxide in both sandstones and carbonates provided that the systems are strongly water-wet.
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measurements of the capillary trapping of super critical carbon dioxide in berea sandstone
Geophysical Research Letters, 2011Co-Authors: Christopher H Pentland, Rehab M Elmaghraby, Stefan Iglauer, Martin J. BluntAbstract:[1] We measure primary drainage capillary pressure and the relationship between initial and residual non-wetting Phase Saturation for a supercritical carbon dioxide (CO2)-brine system in Berea sandstone. We use the semi-permeable disk (porous-plate) coreflood method. Brine and CO2 were equilibrated prior to injection to ensure immiscible displacement. A maximum CO2 Saturation of 85% was measured for an applied capillary pressure of 296 kPa. After injection of brine the CO2 Saturation dropped to 35%; this is less than the maximum trapped Saturation of 48% measured in an equivalent n-decane (oil)-brine experiment. The dimensionless capillary pressure is the same to within experimental error for supercritical CO2-brine, n-decane-brine and a mercury-air system. CO2 is the non-wetting Phase and significant quantities can be trapped by capillary forces. We discuss the implications for CO2 storage.
Dorthe Wildenschild - One of the best experts on this subject based on the ideXlab platform.
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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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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,
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lattice boltzmann simulations of the capillary pressure Saturation interfacial area relationship for porous media
Advances in Water Resources, 2009Co-Authors: Mark L Porter, Marcel G Schaap, Dorthe WildenschildAbstract:Abstract Hysteresis in the relationship between capillary pressure ( P c ) , wetting Phase Saturation ( S w ) and nonwetting–wetting interfacial area per volume ( a nw ) is investigated using multiPhase lattice-Boltzmann simulations of drainage and imbibition in a glass bead porous system. In order to validate the simulations, the P c – S w and a nw – S w main hysteresis loops were compared to experimental data reported by Culligan et al. [Culligan KA, Wildenschild D, Christensen BS, Gray WG, Rivers ML, Tompson AB. Interfacial area measurements for unsaturated flow through porous media. Water Resour Res 2004;40:W12413]. In general, the comparison shows that the simulations are reliable and capture the important physical processes in the experimental system. P c – S w curves, a nw – S w curves and Phase distributions (within the pores) show good agreement during drainage, but less satisfactory agreement during imbibition. Drainage and imbibition scanning curves were simulated in order to construct P c – S w – a nw surfaces. The root mean squared error (RMSE) and mean absolute error (MAE) between drainage and imbibition surfaces was 0.10 mm−1 and 0.03 mm−1, respectively. This small difference indicates that hysteresis is virtually nonexistent in the P c – S w – a nw relationship for the multiPhase system studied here. Additionally, a surface was fit to the main loop (excluding scanning curves) of the drainage and imbibition P c – S w – a nw data and compared to the surface fit to all of the data. The differences between these two surfaces were small (RMSE = 0.05 mm−1 and MAE = 0.01 mm−1) indicating that the P c – S w – a nw surface is adequately represented without the need for the scanning curve data, which greatly reduces the amount of data required to construct the non-hysteretic P c – S w – a nw surface for this data.
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pore scale characteristics of multiPhase flow in porous media a comparison of air water and oil water experiments
Advances in Water Resources, 2006Co-Authors: K A Culligan, Dorthe Wildenschild, Britt Christensen, William G Gray, Mark L RiversAbstract:Abstract Studies of NAPL dissolution in porous media have demonstrated that measurement of Saturation alone is insufficient to describe the rate of dissolution. Quantification of the NAPL–water interfacial area provides a measure of the expected area available for mass transfer and will likely be a primary determinant of NAPL removal efficiency. To measure the interfacial area, we have used a synchrotron-based CMT technique to obtain high-resolution 3D images of flow in a Soltrol–water–glass bead system. The interfacial area is found to increase as the wetting Phase Saturation decreases, reach a maximum, and then decrease as the wetting Phase Saturation goes to zero. These results are compared to previous findings for an air–water–glass bead study; The Soltrol–water interfacial areas were found to peak at similar Saturations as those measured for the air–water system (20–35% Saturation range), however, the peak values were in some cases almost twice as high for the oil-water system. We believe that the observed differences between the air–water and oil–water systems to a large degree can be explained by the differences in interfacial tensions for the two systems.
Duo Zhang - One of the best experts on this subject based on the ideXlab platform.
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a lattice boltzmann study on the impact of the geometrical properties of porous media on the steady state relative permeabilities on two Phase immiscible flows
Advances in Water Resources, 2016Co-Authors: Duo Zhang, K Papadikis, Sai GuAbstract:In the current paper, the effect of the geometrical characteristics of 2-D porous media on the relative permeability in immiscible two-Phase flows is studied. The generation of the different artificial porous media is performed using a Boolean model based on a random distribution of overlapping circles/ellipses, the size and shape of which are chosen to satisfy the specific Minkowski functionals (i.e. volume fraction, solid line contour length, connectivity). The study aims to identify how each different Minkowski functional affects the relative permeability of each Phase at various Saturations of the non-wetting Phase. A 2-D multi-relaxation time (MRT) lattice Boltzmann model (LBM) that can handle high density ratios is employed in the simulation. The relationship between the driving forces G and the relative permeabilities of the two Phases for every artificial structure is quantified. It is found that for high non-wetting Phase Saturations (fully connected flow), a non-linear relationship exists between the non-wetting Phase flow rate and the driving force, whilst this relationship becomes linear at higher magnitudes of the latter. The force magnitude required to approach the linear region is highly influenced by the pore size distribution and the connectivity of the solid Phase. For lower non-wetting Phase Saturation values, its relative permeability in the linear regime decreases as the fraction of small pores in the structure increases and the non-wetting Phase flow becomes disconnected. A strong influence of the solid Phase connectivity is also observed.
Zhenyuan Yin - One of the best experts on this subject based on the ideXlab platform.
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On the importance of Phase Saturation heterogeneity in the analysis of laboratory studies of hydrate dissociation
Applied Energy, 2019Co-Authors: Zhenyuan Yin, George J. Moridis, Praveen LingaAbstract:Abstract Methane hydrates (MHs) have been considered as the future source of energy because of its vast resource volume and high energy density. Energy recovery from MH-bearing sediments has attracted intensifying research activities. Fundamentally, heat transfer, fluid flow through porous media, and the kinetics of hydrate reaction are the three key processes controlling the behavior of MH dissociation and the associated fluid production. Earlier studies have suggested that heterogeneous spatial distribution of SH is inevitable in MH-bearing samples synthesized in laboratory. In this paper, we extend our study to analyze numerically the simulation results from the two realizations of the samples (homogeneous and heterogeneous) to identify differences in the fluid production and to determine if they are sufficiently different. Additionally, we conduct a sensitivity analysis and a statistical analysis on the key transport and kinetic rate parameters that could affect hydrate dissociation and fluid production in the context of a heterogeneous hydrate-bearing sample, in an effort to provide insights that could lead to improved designs for laboratory experiments and (possibly) field applications. Our results suggest that the approximation of an artificial hydrate-bearing core with heterogeneous Phase Saturations by an assumption of uniform Phase Saturation distributions results in practically similar fluid production profile except for the very early stage with maximum 20.0% deviation in the water production. From the sensitivity and statistical analysis, we determine that gas production depends strongly on the kinetic rate constant, Kd0 and the composite thermal conductivity of the hydrate-bearing sediments, λθ; while, water production is very sensitive to Kd0 and the absolute permeability of the sandy medium, k. Understanding the effect of Phase heterogeneity and the relative importance of key parameters on the production behavior of hydrate-bearing sediments could provide basis for novel production technologies that lead to enhanced gas production and energy efficiency in the energy recovery process.
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numerical analysis of experimental studies of methane hydrate formation in a sandy porous medium
Applied Energy, 2018Co-Authors: Zhenyuan Yin, George J. Moridis, Hoon Kiang Tan, Praveen LingaAbstract:Abstract We analyse numerically an earlier experimental study that involved the formation of methane hydrates by the excess water method in a small reactor filled with a sandy porous medium, and seek to address questions about the type of the hydration reaction and the Phase heterogeneity in the resulting hydrate-bearing sand. Using a fine discretization describing the reactor assembly, the experimental process is faithfully replicated numerically. The multi-stage process of hydrate formation is subdivided in 7 steps. The experimental data from the continuously-monitored pressure and temperature during each step are used for comparison against the numerical predictions, the identification of the dominant processes and the determination of the associated parameters through a history-matching process that minimizes deviations between observations and simulation results. The results of this first-ever study on this subject demonstrate unequivocally that the hydration reaction is a kinetic (as opposed to an equilibrium) process, and that the spatial distributions of the various Phases (aqueous, gas and hydrate) at the end of the formation process are strongly heterogeneous. This has serious implications in simulation studies of hydrate dissociation that assume uniform initial Phase Saturation distributions. The history-matching process indicates that (a) the system behaviour is sensitive to some flow parameters (porosity and irreducible water Saturation) only during the first water injection, (b) it is insensitive to the sand intrinsic permeability during all steps of the study, and (c) thermal processes dominate after the first water injection, yielding estimates of the thermal properties of the sand and of time-variable key parameters of the kinetic reaction.
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effect of horizontal wellbore on the production behavior from marine hydrate bearing sediment
Applied Energy, 2018Co-Authors: Zheng Rong Chong, Zhenyuan Yin, Jianzhong Zhao, Jian Hua Rudi Chan, Praveen LingaAbstract:Abstract Natural gas hydrate is a potentially vast energy resource for the future. However, the fundamental behavior of hydrate dissociation during energy recovery is not fully understood due to the complex interplay of Phase change and multiPhase flow within porous media. In this study, the effect of horizontal wellbore incorporation on the simultaneous gas and water production during the dissociation of methane hydrates in sandy sediment (0.1–0.5 mm) was investigated. A horizontal perforated wellbore was incorporated within water saturated hydrate bearing sediments of 40% hydrate, 55% aqueous and 5% gaseous Phase Saturation to mimic marine hydrate sediments, and the gas and water production behavior from horizontal wellbore (HW) was compared with the base case (without well) at 3 bottom hole pressures (BHPs) of 3.5, 4.0, and 4.5 MPa under a constant surrounding temperature of 281.5 K. The evolution of temperature across 12 measured locations within the 1 L sediment demonstrated the significant effect of horizontal wellbore incorporation on heat transfer within sediment. Through the incorporation of horizontal wellbore, a continuous production of gas was observed for an extended period of time as compared to the base cases without a well. The resulting cumulative gas production was enhanced by 5.5–10% at various BHPs; whereas the cumulative water production was significantly reduced by 30.8–36.9% at different BHPs from the base cases. By estimating the percentage of hydrate dissociated, it was found that the incorporation of horizontal wellbore in the current apparatus caused a slower hydrate dissociation, as reflected by a longer time to dissociate 50% (t50,h) and 90% (t90,h) of the hydrates. This study demonstrates the potential of horizontal wellbore incorporation to simultaneously enhance gas production and reduce water production, unveiling a future direction in optimizing gas recovery from hydrate reservoirs through innovative wellbore design, configurations and well placement strategies.
P I Kotov - One of the best experts on this subject based on the ideXlab platform.
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cryovolcanism on the earth origin of a spectacular crater in the yamal peninsula russia
Scientific Reports, 2018Co-Authors: Sergey N Buldovicz, Vanda Khilimonyuk, Andrey Yu Bychkov, Evgeny Ospennikov, Sergey Vorobyev, Aleksey Y Gunar, Evgeny I Gorshkov, E M Chuvilin, Maria Yu Cherbunina, P I KotovAbstract:Geological activity on icy planets and planetoids includes cryovolcanism. Until recently, most research on terrestrial permafrost has been engineering-oriented, and many related phenomena have received too little attention. Although fast processes in the Earth’s cryosphere were known before, they have never been attributed to cryovolcanism. The discovery of a couple of tens of meters wide crater in the Yamal Peninsula aroused numerous hypotheses of its origin, including a meteorite impact or migration of deep gas as a result of global warming. However, the origin of the Yamal crater can be explained in terms of cryospheric processes. Thus, the Yamal crater appears to result from collapse of a large pingo, which formed within a thaw lake when it shoaled and dried out allowing a large talik (that is layer or body of unfrozen ground in a permafrost area) below it to freeze back. The pingo collapsed under cryogenic hydrostatic pressure built up in the closed system of the freezing talik. This happened before the freezing completed, when a core of wet ground remained unfrozen and stored a huge amount of carbon dioxide dissolved in pore water. This eventually reached gas-Phase Saturation, and the resulting overpressure came to exceed the lithospheric confining stress and the strength of the overlying ice. As the pingo exploded, the demarcation of the crater followed the cylindrical shape of the remnant talik core.
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cryovolcanism on the earth origin of a spectacular crater in the yamal peninsula russia
Scientific Reports, 2018Co-Authors: Sergey N Buldovicz, Vanda Khilimonyuk, Andrey Yu Bychkov, Evgeny Ospennikov, Sergey Vorobyev, Aleksey Y Gunar, Evgeny I Gorshkov, E M Chuvilin, Maria Yu Cherbunina, P I KotovAbstract:Geological activity on icy planets and planetoids includes cryovolcanism. Until recently, most research on terrestrial permafrost has been engineering-oriented, and many related phenomena have received too little attention. Although fast processes in the Earth’s cryosphere were known before, they have never been attributed to cryovolcanism. The discovery of a couple of tens of meters wide crater in the Yamal Peninsula aroused numerous hypotheses of its origin, including a meteorite impact or migration of deep gas as a result of global warming. However, the origin of the Yamal crater can be explained in terms of cryospheric processes. Thus, the Yamal crater appears to result from collapse of a large pingo, which formed within a thaw lake when it shoaled and dried out allowing a large talik (that is layer or body of unfrozen ground in a permafrost area) below it to freeze back. The pingo collapsed under cryogenic hydrostatic pressure built up in the closed system of the freezing talik. This happened before the freezing completed, when a core of wet ground remained unfrozen and stored a huge amount of carbon dioxide dissolved in pore water. This eventually reached gas-Phase Saturation, and the resulting overpressure came to exceed the lithospheric confining stress and the strength of the overlying ice. As the pingo exploded, the demarcation of the crater followed the cylindrical shape of the remnant talik core.