CT Imaging of Low-Permeability, Dual-Porosity Systems Using High X-ray Contrast Gas

Vega, Bolivia; Dutta, Abhishek; Kovscek, Anthony R.

doi:10.1007/s11242-013-0232-0

Cited by 108 publications

(43 citation statements)

References 28 publications

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“…For typical gas shale, porosity ranges from 1% to 10% [1,5,39], and this number is lower than that for sandstones. Hence, the average coordination number was assumed to be three in this study.…”

Section: Shale Matrix Pore Network Modelmentioning

confidence: 99%

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix

Zhang

Meegoda

2017

Materials

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Extremely low permeability due to nano-scale pores is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on pore pressure, porosity, pore throat size and gas type. The pore network model is a practical way to explain the macro flow behavior of porous media from a microscopic point of view. In this research, gas flow in a shale matrix is simulated using a previously developed three-dimensional pore network model that includes typical bimodal pore size distribution, anisotropy and low connectivity of the pore structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir pressures corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas pressure, and hence the apparent permeability is not a unique value during the shale gas exploitation, and simulations suggested that a constant permeability for continuum-scale simulation is not accurate. Hence, the reservoir pressures of different shale gas exploitations should be considered. In addition, a sensitivity analysis was also performed to determine the contributions to apparent permeability of a shale matrix from petro-physical properties of shale such as pore throat size and porosity. Finally, the impact of connectivity of nano-scale pores on shale gas flux was analyzed. These results would provide an insight into understanding nano/micro scale flows of shale gas in the shale matrix.

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Section: Shale Matrix Pore Network Modelmentioning

confidence: 99%

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix

Zhang

Meegoda

2017

Materials

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“…In light of this requirement, krypton gas was chosen as the working fluid for this study due to its high mass attenuation coefficient, chemical inertness, relatively low cost (compared to other gases with these qualities), and lack of health hazards. Krypton has previously been used with great success as a contrast agent in XCT studies of pulmonary absorption in the medical field (Simon 2005) and rock porosity in the context of petroleum engineering (Vega et al 2014). Linear and mass attenuation coefficients for krypton and other pertinent materials are illustrated in Fig.…”

Section: Theoretical Implications For Experimental Designmentioning

confidence: 99%

Characterization of scalar mixing in dense gaseous jets using X-ray computed tomography

et al. 2015

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“…If the air is removed and replaced by a larger contrast gas such as krypton (ρ ~ 0.003749 g/cc, m.a.c [8 keV] = 9.651E+01 cm 2 /g) (NIST, http://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html), a greater contrast image of the pore space should be achieved. Details of this method and its application to the study of core-scale gas shale samples are found in Vega et al, 2013. Provided the solid matter does not change between one gas and the other, one can assume the difference between both images will correspond to the pore space accessed by gas.…”

Section: Sample Preparation and Mountingmentioning

confidence: 99%

Nanoscale Visualization of Gas Shale Pore and Textural Features

Vega

Andrews

Liu

et al. 2013

Unconventional Resources Technology Conference, Denver, Colorado, 12-14 August 2013

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Characterization of gas shale pore topology and composition supports efforts to produce methane as well as assess the feasibility of using depleted organic-rich shale reservoirs for carbon dioxide sequestration. Imaging performed with Full-field Transmission X-Ray Microscopy technology to characterize gas shale structure and heterogeneity was conducted on a set of Barnett and Haynesville gas shale samples to help determine how the physical and chemical processes associated with CO 2 in organic-rich shales affect injectivity and storage capacity (over long periods of time), and the ability of the shale to sequester CO 2 (as both a free and adsorbed phase). The images show the presence of density-differentiated areas that might be an indication of predominantly organic and inorganic matter matrices, along with lowest-density lineal pathways that point to the potential presence of micro cracks. Using an innovative imaging technique at the nanoscale, high X-ray contrast gas was applied to the sample and the images obtained show visual enhancement of particular rock features, such as available porous space and microcracks.

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CT Imaging of Low-Permeability, Dual-Porosity Systems Using High X-ray Contrast Gas

Cited by 108 publications

References 28 publications

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix

Characterization of scalar mixing in dense gaseous jets using X-ray computed tomography

Nanoscale Visualization of Gas Shale Pore and Textural Features

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