Microtomography and Pore-Scale Modeling of Two-Phase Fluid Distribution

Silin, Dmitriy; Tomutsa, Liviu; Benson, Sally M.; Patzek, Tadeusz W

doi:10.1007/s11242-010-9636-2

Cited by 117 publications

(75 citation statements)

References 52 publications

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“…X-ray micro-computed tomography (µ-CT) multiphase flow experiments are aimed at imaging the in situ fluid phase distributions in porous media (Wildenschild et al 2005;Silin et al 2010;Iglauer et al 2011;Setiavan et al 2012;Andrew et al 2014). Recently, fast synchrotron-based µ-CT has been used to image fluid distributions under dynamic conditions (Berg et al 2013b); the term "dynamic" means that fluid flow is maintained while imaging, with ms integration times thus enabling dynamic process studies on basis of a series of images.…”

Section: Introductionmentioning

confidence: 99%

“…Also bias likely depends on the characteristics and quality of the image data, and likely has to be evaluated for each data series. As best practice, macroscopic properties obtained from computer modeling are often used as validation criteria, whereby the calculated pore structure-related values like porosity (Iassonov et al 2009;Vogel et al 2005), permeability , and capillary pressure curves (Silin et al 2010), are compared to experimental data. Permeability can be derived from Lattice-Boltzmann (LBM) single-phase flow simulations on the segmented images (Chen et al 1991;Coles et al 1998;Ferreol and Rothmann 1995;Lehmann et al 2008;Vogel et al 2005;Zhang and Kwok 2006).…”

Section: Introductionmentioning

confidence: 99%

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Fast X-ray Micro-Tomography of Multiphase Flow in Berea Sandstone: A Sensitivity Study on Image Processing

et al. 2014

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Synchrotron-based fast micro-tomography is the method of choice to observe in situ multiphase flow and displacement dynamics on the pore scale. However, the image processing workflow is sensitive to a suite of manually selected parameters which can lead to ambiguous results. In this work, the relationship between porosity and permeability in response to systematically varied gray-scale threshold values was studied for different segmentation approaches on a dataset of Berea sandstone at a voxel length of 3 µm. For validation of the image processing workflow, porosity, permeability, and capillary pressure were compared to laboratory measurements on a larger-sized core plug of the same material. It was found that for global thresholding, minor variations in the visually permissive range lead to large variations in porosity and even larger variations in permeability. The latter is caused by changes in the pore-scale flow paths. Pore throats were found to be open for flow at large thresholds but closed for smaller thresholds. Watershed-based segmentation was found to be significantly more robust to manually chosen input parameters. Permeability and capillary pressure closely match experimental values; for capillary pressure measurements, the plateau of calculated capillary pressure curves was similar to experimental curves. Modeling on structures segmented with hysteresis thresholding was found to overpredict experimental capillary pressure values, while calculated permeability showed reasonable agreement to experimental data. This demonstrates that a good representation of permeability or capillary pressure alone is not a sufficient quality criterion for appropriate segmentation, but the data should be validated with both parameters. However, porosity is the least reliable quality criterion. In the segmented images, always a lower porosity was found compared to experimental values due to micro-porosity below the imaging resolution. As a result, it is recommended to base the validation of image processing workflows on permeability and capillary pressure and not on porosity. Decane-brine distributions from a multiphase flow experiment were modeled in a thus validated µ-CT pore space using a morphological approach which captures only capillary forces. A good overall correspondence was found when comparing (capillary-controlled) equilibrium fluid distributions before and after pore-scale displacement events.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fast X-ray Micro-Tomography of Multiphase Flow in Berea Sandstone: A Sensitivity Study on Image Processing

et al. 2014

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“…In such a complex system, with such an extensive and poorly understood set of inter-dependent variables, experiments using idealized pore structures 19 or analogue fluids 20,21 may not be applicable to flow processes in the subsurface. Imaging multiple fluids at conditions representative of a prospective CO 2 injection formation has, however, remained a challenge 22 . In this study we outline a methodology for the examination of multi-fluid behavior at reservoir conditions, focusing on the examination of capillary trapping Experiments with soluble fluids provide an additional challenge when using lengthy acquisition times, as CO 2 will diffuse through the polymeric portions of the experimental assembly, reducing the in-situ fluid saturation.…”

Section: Introductionmentioning

confidence: 99%

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

Andrew

Bijeljic

Blunt

2015

JoVE

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X-ray microtomography was used to image, at a resolution of 6.6 µm, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO 2 storage. Chemical equilibrium between the CO 2 , brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO 2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO 2 were trapped, with a residual saturation of 0.203 ± 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

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“…Some of the technical difficulties, when visualising pore-scale resolving processes are the required small sample size and thus weakness of such thin samples as well as the need to obtain sufficient contrast between the pore fluids inside the material and the related difficulties to threshold these correctly (Silin et al, 2011). In 2011, Iglauer et al (2011were able to image residual CO 2 in sandstone by means of X-ray CT at temperature and pressure corresponding to CO 2 in its supercritical state.…”

Section:  Multi-scale Imagingmentioning

confidence: 99%

High-resolution X-ray computed tomography in geosciences: A review of the current technology and applications

Cnudde

Boone

2013

Earth-Science Reviews

1,232

700

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Please cite this article as: Cnudde, V., Boone, M.N., "High-resolution X-ray computed tomography in geosciences: a review of the current technology and applications", Earth Science Reviews (2013Reviews ( ), doi: 10.1016Reviews ( /j.earscirev.2013 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T AbstractHigh-resolution X-ray Computed Tomography (HRXCT) or micro-CT (µCT) is a frequently used non-destructive 3D imaging and analysis technique for the investigation of internal structures of a large variety of objects, including geomaterials. Although the possibilities of X-ray micro-CT are becoming better appreciated in earth science research, the demands on this technique are also approaching certain physical limitations. As such, there remains a lot of research to be done in order to solve all the technical problems that occur when higher demands are put on the technique. In this paper, a review of the principle, the advantages and limitations of X-ray CT itself are presented, together with an overview of some current applications of micro-CT in geosciences. One of the main advantages of this technique is the fact that it is a non-destructive characterization technique which allows 4D monitoring of internal structural changes at resolutions down to a few hundred nanometers. Limitations of this technique are the operator dependency for the 3D image analysis from the reconstructed data, the discretations effects and possible imaging artefacts. Driven by the technological and computational progress, the technique is continuously growing as an analysis tool in geosciences and is becoming one of the standard techniques, as is shown by the large and still increasing number of publications in this research area. It is foreseen that this number will continue to rise, and micro-CT will become an indispensable technique in the field of geosciences.

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Microtomography and Pore-Scale Modeling of Two-Phase Fluid Distribution

Cited by 117 publications

References 52 publications

Fast X-ray Micro-Tomography of Multiphase Flow in Berea Sandstone: A Sensitivity Study on Image Processing

Fast X-ray Micro-Tomography of Multiphase Flow in Berea Sandstone: A Sensitivity Study on Image Processing

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

High-resolution X-ray computed tomography in geosciences: A review of the current technology and applications

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