Publications

Results 276–300 of 345

Search results

Jump to search filters

Pore-scale investigation on stress-dependent characteristics of granular packs and the impact of pore deformation on fluid distribution

Geofluids

Yoon, Hongkyu; Klise, Katherine A.; Torrealba, Victor A.; Karpyn, Zuleima T.; Crandall, D.

Understanding the effect of changing stress conditions on multiphase flow in porous media is of fundamental importance for many subsurface activities including enhanced oil recovery, water drawdown from aquifers, soil confinement, and geologic carbon storage. Geomechanical properties of complex porous systems are dynamically linked to flow conditions, but their feedback relationship is often oversimplified due to the difficulty of representing pore-scale stress deformation and multiphase flow characteristics in high fidelity. In this work, we performed pore-scale experiments of single- and multiphase flow through bead packs at different confining pressure conditions to elucidate compaction-dependent characteristics of granular packs and their impact on fluid flow. A series of drainage and imbibition cycles were conducted on a water-wet, soda-lime glass bead pack under varying confining stress conditions. Simultaneously, X-ray micro-CT was used to visualize and quantify the degree of deformation and fluid distribution corresponding with each stress condition and injection cycle. Micro-CT images were segmented using a gradient-based method to identify fluids (e.g., oil and water), and solid phase redistribution throughout the different experimental stages. Changes in porosity, tortuosity, and specific surface area were quantified as a function of applied confining pressure. Results demonstrate varying degrees of sensitivity of these properties to confining pressure, which suggests that caution must be taken when considering scalability of these properties for practical modeling purposes. Changes in capillary number with confining pressure are attributed to the increase in pore velocity as a result of pore contraction. Furthermore, this increase in pore velocity was found to have a marginal impact on average phase trapping at different confining pressures.

More Details
TYPE Journal Article YEAR 2015
DOIOSTI

Multiscale characterization of physical, chemical, and mechanical heterogeneity of mudstones

49th US Rock Mechanics / Geomechanics Symposium 2015

Yoon, Hongkyu; Dewers, Thomas; Grigg, J.; Mozley, P.

Multiscale characteristics of anisotropic, heterogeneous pore structure and compositional (e.g., kerogen, clay, cement, etc) distribution profoundly influence the hydro, mechanical, and chemical response of shale materials during stimulation and production. In this work the impact of these lithologic heterogeneities on physical, chemical, and mechanical properties is investigated over a micron to core scale of shale samples for Cretaceous Mancos Shale. Principal macroscopic lithofacies at a decimeter scale are petrographically examined. Thin sections (∼2-3cm) impregnated with fluorochromes are examined using laser scanning confocal microscopy and optical microscopy with different filters to characterize micro-facies (i.e., texture patterns) and using electron microprobe to identify the mineralogical distribution. Advanced multiscale image analysis for texture classification will be used to identify key features of samples which will be further analyzed using dual focused ion beam-scanning electron microscopy, aberration corrected-scanning TEM and energy dispersive X-ray spectrometry for nano-pore and organic-pore structures and mineralogies at nano scale. This characterization will be examined against experimental data including acoustic emission and nano-indentation measurements of elastic properties using focused ion-beam milled pillars. Finally, multiscale 3-D image stacks will be segmented to rigorously test the scale of a representative elementary volume based on multiple measures from image analysis and pore-scale simulations.

More Details
TYPE Conference Poster YEAR 2015
OSTIScopus
Results 276–300 of 345
Results 276–300 of 345
Top