Residual CO<sub>2</sub>imaged with X-ray micro-tomography

Iglauer, Stefan; Paluszny, Adriana; Pentland, Christopher; Blunt, Martin J.

doi:10.1029/2011gl049680

Cited by 319 publications

(260 citation statements)

References 26 publications

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“…For 3D structures, numerical simulations suggest that τ is typically larger than 2 (40−43). Values of τ larger than 2 were also observed in direct measurements of trapped cluster distributions in clastic rocks and synthetic porous media (16,19,20).…”

Section: Analysis Of Fragmented Oil Dropletsmentioning

confidence: 72%

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Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Pak

Butler

Geiger

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

153

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Using X-ray computed microtomography, we have visualized and quantified the in situ structure of a trapped nonwetting phase (oil) in a highly heterogeneous carbonate rock after injecting a wetting phase (brine) at low and high capillary numbers. We imaged the process of capillary desaturation in 3D and demonstrated its impacts on the trapped nonwetting phase cluster size distribution. We have identified a previously unidentified pore-scale event during capillary desaturation. This pore-scale event, described as droplet fragmentation of the nonwetting phase, occurs in larger pores. It increases volumetric production of the nonwetting phase after capillary trapping and enlarges the fluid−fluid interface, which can enhance mass transfer between the phases. Droplet fragmentation therefore has implications for a range of multiphase flow processes in natural and engineered porous media with complex heterogeneous pore spaces.droplet fragmentation | X-ray computed microtomography | pore-scale imaging | heterogeneous porous media | carbonate rock M ultiphase fluid displacement processes in porous media are important for a broad range of natural and engineering applications such as transport of nonaqueous phase liquid contaminants in aquifers, oil and gas production from hydrocarbon reservoirs, subsurface CO 2 storage, or gas transport in fuel cells. Herein, capillary trapping is a fundamental mechanism that causes immobilization of a portion of the resident nonwetting phase when it is displaced by an invading wetting phase. As a result, production of the nonwetting phase is always less than 100%.The pore-scale physics of capillary trapping are broadly understood, as the underlying mechanisms such as piston-like displacement, snap-off and film development have been observed in physical micromodel experiments and quantitative theories have been established for them (1-4). The conventional view considers such pore-scale processes to occur between multiple pores, i.e., they are interpore processes and the pores are defined as volumes connected by narrower pore throats. By contrast, intrapore processes, as presented in this paper, are not well established in the literature. During drainage (i.e., where a nonwetting phase displaces the wetting phase), the wetting phase can establish films in the corners of the pores, which results in its continuous production and hence low residual saturations of the wetting phase. During imbibition (i.e., where the wetting phase displaces a nonwetting phase), swelling of the corner wetting films causes snap-off of the nonwetting phase, which results in capillary trapping of the nonwetting phase. The trapped nonwetting phase exists as disconnected ganglia within the pore network. Numerical pore network models have been developed to include these porelevel mechanisms with the aim of predicting the macroscopic flow properties of porous materials such as the structure of the phase distributions, residual saturation, relative permeability functions, and capillary pressure curves. Some of these mod...

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Section: Analysis Of Fragmented Oil Dropletsmentioning

confidence: 72%

“…A particular focus has been on capillary trapping (16)(17)(18)(19)(20). Using synchrotron X-ray μCT facilities, it has also become possible to visualize dynamic pore-scale mechanisms, including snap-off and Haines jumps (21).…”

mentioning

confidence: 99%

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Pak

Butler

Geiger

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

153

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“…A major experimental shortcoming in the first study to use micro-CT to examine CO 2 at reservoir conditions was the use of metal lines to control the flow to and from the core-holder 27 . As the sample is rotated relative to the pumps, the flow lines also need to be rotated.…”

Section: Introductionmentioning

confidence: 99%

“…A larger coreholder size would have required the detector to be much further from the source to achieve the same geometric magnification, reducing the x-ray flux incident on the detector and therefore increasing required projection exposure times. The flow cell used in these experiments was based on a traditional Hassler cell design, built around a carbon fiber sleeve, with a sleeve design similar to that used by Iglauer et al 27 , but with two significant alterations: 1) The carbon fiber composite used in the sleeve manufacture was changed from T700 fibers, with a stiffness of 230 GPa, to M55 fibers, with a stiffness of 550 GPa. This not only reduced the amount of sample movement during tomography acquisition, but also increased the maximum working pressure of the cell from 20 MPa to 50 MPa.…”

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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“…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

1,263

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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Residual CO₂imaged with X-ray micro-tomography

Cited by 319 publications

References 26 publications

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

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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Residual CO2imaged with X-ray micro-tomography

Cited by 319 publications

References 26 publications

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

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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Residual CO₂imaged with X-ray micro-tomography