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Berlin Brandenburg

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  • Imbibition
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  • 1
    In: Geophysical Research Letters, 28 September 2016, Vol.43(18), pp.9677-9685
    Description: We utilize synchrotron X‐ray tomographic imaging to investigate the pore‐scale characteristics and residual trapping of supercritical CO (scCO) over the course of multiple drainage‐imbibition (D‐I) cycles in Bentheimer sandstone cores. Capillary pressure measurements are paired with X‐ray image‐derived saturation and connectivity metrics which describe the extent of drainage and subsequent residual (end of imbibition) scCO trapping. For the first D‐I cycle, residual scCO trapping is suppressed due to high imbibition capillary number (Ca ≈ 10); however, residual scCO trapping dramatically increases for subsequent D‐I cycles carried out at the same Ca value. This behavior is not predicted by conventional multiphase trapping theory. The magnitude of scCO trapping increase is hysteretic and depends on the relative extent of the sequential drainage processes. The hysteretic pore‐scale behavior of the scCO‐brine‐sandstone system observed in this study suggests that cyclic multiphase flow could potentially be used to increase scCO trapping for sequestration applications. We observe cyclic pore‐scale behavior of supercritical CO2 (scCO2) via synchrotron X‐ray microtomography Residual scCO2 saturation increases over multiple drainage‐imbibition (D‐I) cycles reaching a value of 50% after three cycles The ultimate driver for this behavior may be a combination of cycling and associated surface chemistry reactions
    Keywords: Co 2 Sequestration ; Residual Trapping ; Capillary Trapping ; Cyclic Injections ; X‐Ray Microtomography ; Multiphase Flow
    ISSN: 0094-8276
    E-ISSN: 1944-8007
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  • 2
    Language: English
    In: Advances in Water Resources, September 2012, Vol.46, pp.55-62
    Description: ► Computed tomography datasets were analyzed for interfacial curvature. ► Curvature and transducer-based measurements compare well. ► Disconnected and connected phase interfaces have significantly different curvatures. ► Connected phase interfacial curvature relaxes as the system equilibrates. Synchrotron-based tomographic datasets of oil–water drainage and imbibition cycles have been analyzed to quantify phase saturations and interfacial curvature as well as connected and disconnected fluid configurations. This allows for close observation of the drainage and imbibition processes, assessment of equilibrium states, and studying the effects of fluid phase disconnection and reconnection on the resulting capillary pressures and interfacial curvatures. Based on this analysis estimates of capillary pressure calculated from interfacial curvature can be compared to capillary pressure measured externally with a transducer. Results show good agreement between curvature-based and transducer-based measurements when connected phase interfaces are considered. Curvature measurements show a strong dependence on whether an interface is formed by connected or disconnected fluid and the time allowed for equilibration. The favorable agreement between curvature-based and transducer-based capillary pressure measurements shows promise for the use of image-based estimates of capillary pressure for interfaces that cannot be probed with external transducers as well as opportunities for a detailed assessment of interfacial curvature during drainage and imbibition.
    Keywords: Capillary Pressure ; Interfacial Curvature ; Young–Laplace ; Drainage ; Imbibition ; Computed Microtomography ; Engineering
    ISSN: 0309-1708
    E-ISSN: 1872-9657
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  • 3
    Language: English
    In: Advances in Water Resources, December 2018, Vol.122, pp.251-262
    Description: We introduce a new method for defining a pore-body to pore-throat aspect ratio from segmented 3D image data, based on a connectivity metric applicable to porous media with widely varying pore-space connectivity and pore-space morphology. The ‘Morphological Aspect Ratio’ (MAR) is identified from the pore-space connectivity, using the Euler number (χ) as a function of a pore-space size defined by a morphological opening (erosion and dilation) of the pore space. We show that residual non-wetting phase trapping in porous media resulting from secondary imbibition scales with the MAR. Trapping was investigated in a Bentheimer sandstone core and five columns of partially sintered glass-particle packs with different combinations of glass beads and crushed glass ranging in size from 0.3 to 1.2 mm, resulting in porosity levels of 22–36%. Residual non-wetting phase trapping scales with the MAR, in contrast to the aspect ratio calculated with the traditional Maximum Inscribed Sphere (MIS) algorithm applied after partitioning the pore space into pore bodies and pore throats with a watershed transform followed by a region merging algorithm. This novel aspect ratio is a robust method that is less affected by segmentation errors compared to other methods for calculating aspect ratio and is applicable to residual non-wetting phase trapping resulting from capillary-driven flow of a wetting fluid through water-wet porous media.
    Keywords: Connectivity ; Capillary-Dominated Flow ; Morphological Opening ; Nonwetting Phase Trapping ; X-Ray Micro-Tomography ; Porous Media ; Engineering
    ISSN: 0309-1708
    E-ISSN: 1872-9657
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  • 4
    Language: English
    In: Advances in Water Resources, May 2015, Vol.79, pp.91-102
    Description: 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 –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, ) 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 ( ≈ 0) to very high connectivity ( ≈ 1). We propose that multiphase fluid-porous medium systems can be 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 sequestration scenarios.
    Keywords: Co2 Sequestration ; Topology ; Pore-Scale ; Force Balance ; Nonwetting Phase Trapping ; X-Ray Microtomography ; Engineering
    ISSN: 0309-1708
    E-ISSN: 1872-9657
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  • 5
    Language: English
    In: 2012
    Description: Acknowledgment is made to the Donors of the American ChemicalSociety Petroleum Research Fund for support (or partial support)of this research (grant number 48505-AC9) and by US NSF(EAR 337711 and EAR 0610108). Microtomography was performedat GeoSoilEnviroCARS (Sector 13), Advanced Photon Source (APS),Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation-Earth Sciences (EAR-0217473),Dept. of Energy-Geosciences (DE-FG01-94ER14466) and the Stateof Illinois. Additionally, we would like to acknowledge the followingpeople for their help with either collecting the data: Mark Rivers(GSECARS APS/University of Chicago), or with interpreting theresults: James McClure (University of North Carolina), Casey Miller(University of North Carolina), William Gray (University of NorthCarolina), and Adrian Sheppard (Australian National University).
    Description: Synchrotron-based tomographic datasets of oil–water drainage and imbibition cycles have been analyzed to quantify phase saturations and interfacial curvature as well as connected and disconnected fluid configurations. This allows for close observation of the drainage and imbibition processes, assessment of equilibrium states, and studying the effects of fluid phase disconnection and reconnection on the resulting capillary pressures and interfacial curvatures. Based on this analysis estimates of capillary pressure calculated from interfacial curvature can be compared to capillary pressure measured externally with a transducer. Results show good agreement between curvature-based and transducer-based measurements when connected phase interfaces are considered. Curvature measurements show a strong dependence on whether an interface is formed by connected or disconnected fluid and the time allowed for equilibration. The favorable agreement between curvature-based and transducer-based capillary pressure measurements shows promise for the use of image-based estimates of capillary pressure for interfaces that cannot be probed with external transducers as well as opportunities for a detailed assessment of interfacial curvature during drainage and imbibition.
    Description: This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/advances-in-water-resources/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. ; 10.1016/j.advwatres.2012.05.009
    Keywords: Drainage ; Computed Microtomography ; Capillary Pressure ; Young–Laplace ; Interfacial Curvature ; Imbibition
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 6
    Language: English
    In: Advances in Water Resources, December 2013, Vol.62, pp.47-58
    Description: This work examines the influence of (i.e. post drainage) nonwetting (NW) fluid topology on total (i.e. after imbibition) NW phase saturation. Brine and air (used as a proxy for supercritical CO ) flow experiments were performed on Bentheimer sandstone; results were quantified via imaging with X-ray computed microtomography (X-ray CMT), which allows for three dimensional, non-destructive, pore-scale analysis of the amount, distribution, and connectivity of NW phase fluid within the sandstone cores. In order to investigate the phenomenon of fluid connectivity and how it changes throughout flow processes, the Bentheimer sandstone results are compared to previously collected X-ray CMT data from similar experiments performed in a sintered glass bead column, a loose packed glass bead column, and a column packed with crushed tuff. This allows us to interpret the results in a broader sense from the work, and draw conclusions of a more general nature because they are not based on a single pore geometry. Connectivity is quantified via the of the NW fluid phase; the Euler number of a particular sample is normalized by the maximum connectivity of the media, i.e. the Euler number of the system at 100% NW phase saturation. General connectivity-saturation relationships were identified for the various media. In terms of trapping, it was found that residual NW phase trapping is dependent on initial (i.e. post-drainage) NW phase connectivity as well as imbibition capillary number for the Bentheimer sandstone. Conversely, the sintered glass bead column exhibited no significant relationship between trapping and NW topology. These findings imply that for a CO sequestration scenario, capillary trapping is controlled by both the imbibition capillary number and the initial NW phase connectivity: as capillary number increases, and the normalized initial Euler number approaches a value of 1.0, capillary trapping is suppressed. This finding is significant to CO sequestration, because both the drainage (CO injection) and imbibition (subsequent water injection or infiltration) processes can be engineered in order to maximize residual trapping within the porous medium. Based on the findings presented here, we suggest that both the Euler number-saturation and the capillary number-saturation relationships for a given medium should be considered when designing a CO sequestration scenario.
    Keywords: Connectivity ; Topology ; Co2 Sequestration ; Capillary Trapping ; Porous Media ; X-Ray Tomography ; Engineering
    ISSN: 0309-1708
    E-ISSN: 1872-9657
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  • 7
    Language: English
    In: International Journal of Greenhouse Gas Control, November 2015, Vol.42, pp.1-15
    Description: Geological carbon sequestration is being considered worldwide as a means of mitigating anthropogenic emission of greenhouse gases. During sequestration, carbon dioxide (CO ) gas effluent is captured from coal-fired power plants or other concentrated emission sources and injected into saline aquifers or depleted oil reservoirs for long term storage. In an effort to fully understand and optimize CO trapping efficiency, the capillary mechanisms that immobilize subsurface CO were analyzed at the pore-scale. Pairs of proxy fluids representing the potential range of in-situ conditions of supercritical CO (nonwetting fluid) and brine (wetting fluid) were used during experimentation. The two fluids were imbibed and drained from a flow cell apparatus containing a sintered glass bead core. Fluid parameters (such as interfacial tension and fluid viscosities) and flow rate were altered to characterize their relative impact on capillary trapping. Computed x-ray microtomography (microCT) was used to quantify immobilized nonwetting fluid volumes after imbibition and drainage events. MicroCT-analyzed data suggests that capillary trapping in sintered glass bead (a mildly consolidated porous medium) is dictated by the capillary number ( ), the viscosity ratio ( ), and the Bond number ( ) of the system, reflecting that all three viscous, capillary, and gravity forces affect the displacement process to varying degree as their relative importance changes. The amount of residual trapped nonwetting phase was observed to increase with increasing nonwetting fluid viscosity, and with decreasing density difference of the fluids; this suggests that CO sequestration can potentially be engineered for optimal trapping through alterations to the viscosity or density of supercritical CO .
    Keywords: Co2 Sequestration ; Capillary Trapping ; Proxy Fluids ; Viscosity ; Density ; Bond Number ; Capillary Number ; Viscosity Ratio ; Engineering
    ISSN: 1750-5836
    E-ISSN: 1878-0148
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  • 8
    Language: English
    In: Advances in Water Resources, 2009, Vol.32(11), pp.1632-1640
    Description: Hysteresis in the relationship between capillary pressure , wetting phase saturation and nonwetting–wetting interfacial area per volume is investigated using multiphase lattice-Boltzmann simulations of drainage and imbibition in a glass bead porous system. In order to validate the simulations, the and 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. curves, 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 surfaces. The root mean squared error (RMSE) and mean absolute error (MAE) between drainage and imbibition surfaces was 0.10 mm and 0.03 mm , respectively. This small difference indicates that hysteresis is virtually nonexistent in the relationship for the multiphase system studied here. Additionally, a surface was fit to the main loop (excluding scanning curves) of the drainage and imbibition data and compared to the surface fit to all of the data. The differences between these two surfaces were small (RMSE = 0.05 mm and MAE = 0.01 mm ) indicating that the 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 surface for this data.
    Keywords: Multiphase Flow ; Lattice-Boltzmann ; Interfacial Area ; Capillary Pressure ; Porous Media ; Computed Microtomography ; Engineering
    ISSN: 0309-1708
    E-ISSN: 1872-9657
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  • 9
    In: Water Resources Research, December 2007, Vol.43(12), pp.n/a-n/a
    Description: A Shan‐Chen–type multiphase lattice Boltzmann (LB) model was applied to observed computed microtomography data from water‐air and water‐Soltrol displacement experiments in a glass bead porous medium. Analysis of the Bond, Reynolds, and Capillary numbers for these systems showed that capillary forces were dominant removing the need to model viscous, gravitational, and density effects. A numerical parameterization of the LB model yielded lattice surface tension and contact angle, and appropriate pressure boundary conditions. Two scaling relations provided a link between lattice pressure and physical pressure and lattice time and physical time. Results showed that there was a good match between measured and simulated pressure‐saturation data for the water‐air system, but that there were large differences between the simulations and observations for the water‐Soltrol system. The discrepancies for the water‐Soltrol system were probably due to inconsistencies between experimental conditions and simulated conditions such as nonzero contact angle in the experiments. Analysis of saturation profiles indicated increasing saturation near the wetting boundary and decreasing saturations near the nonwetting boundary. We attribute these saturation transitions to pore‐neck and percolation effects. While computationally intensive, results of this study were very encouraging for the application of LB simulations to microscale interfacial phenomena. Future studies will carry out a further validation in terms of interfacial areas, contact lines, and fluid distributions.
    Keywords: Lattice Boltzmann ; Pressure Saturation ; Comparison
    ISSN: 0043-1397
    E-ISSN: 1944-7973
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