Ph.D. Candidate in Energy Resources Engineering, Stanford University
MSc. Petroleum Eng., Stanford University
BSc. Chemical Eng., University of Texas, Austin

Honors & Awards

  • Recipient Scholarship, Kwanjeong Educational Foundation, Rep. of Korea (2012)
  • University Honors, The University of Texas at Austin (2008 ~ 2012)
  • Recipient Scholarship, Kwanjeong Educational Foundation (2012)
  • Engineering Honors, The University of Texas at Austin (2010 ~ 2012)
  • Recipient of Distinguished College scholar and Medallion, The University of Texas at Austin (Honors Day 2010)
  • Recipient of Fellowship from Undergraduate Research Funds, The University of Texas at Austin (2011)
  • Recipient of Scholarship, Korean-American Scientist and Engineer Association (2011)

Boards, Advisory Committees, Professional Organizations

  • Member, Omega Chi Epsilon National Chemical Engineering Honor society (2010 - 2012)
  • Graduate student member, Society of Petroleum Engineers (2013 - Present)
  • External Vice President, Korean Student Association at Stanford (2013 - 2014)

Stanford Advisors

Current Research and Scholarly Interests

Improved understanding of the physicochemical mechanisms controlling the interplay between oil, water,and rock during EOR processes at pore scale is vital to achieve successful applications of enhanced oil recovery (EOR). Microfluidics provides an experimental platform to probe such interplay. The present work addresses greater realism in pore structure and visualization of micromodels for characterization of single and multiphase flows.

We describe 4 advancements, as follows, and representative results. First, we demonstrate improved 3D structural realism of pores inside etched-silicon microfluidic devices. In particular, we etch the micropores 1.5 to 21 μm width) within a carbonate pore network less deeply than the wider macropores (>21 μm width). Second, we apply micro-particle image velocimetry (μ-PIV) to so-called end-point relative permeability measurements of oil and water as well as pore-scale observationsmduring imbibition and drainage processes. The μ-PIV technique provides insights into the fluid dynamics within microfluidic channels and relevant fluid velocities controlled predominantly by changes in pore width and depth. Third, we demonstrate that micromodels may be monitored using advanced spectral imaging that enables real-time and in-situ quantification of the local viscosity of shear-thinning and viscoelastic fluids. Spectral imaging of in situ viscosity paves the way for validation and optimization of computational fluid dynamics models for non-Newtonian viscoelastic EOR polymers. Fourth, we show the application of deep-learning to the micromodel images for the automated analysis of surface properties. Specifically, understanding wettability of porous media, namely the relative affinity of the fluids for the solid, and its influence on the efficiency of wetting-phase displacement of non-wetting phase is a key factor determining multiphase flow. Hence, we want to achieve a systematic methodology to study themlarger domain of porous media that consists of a tremendous number of complex interplays between surface and reservoir fluids at the pore and pore network scale. With proper training, deep-learning has a great potential to serve as a quick and comprehensive image classification and evaluation tool.

Lab Affiliations

All Publications

  • Toward Reservoir-on-a-Chip: Multi-Scale Framework to Access Surfactants for Enhancing Oil Displacement in Carbonates Using CaCO3-Coated Micromodel ACS Applied Materials & Interfaces Yun, W., Change, S., Cogswell, D., et al 2018; Submitted
  • Magnetic SERS Composite Nanoparticles for Microfluidic Oil Reservoir Tracer Detection and Nanoprobe Applications ACS Applied Nano Materials Chang, S., Yun, W., Poitzsch, M., Wang, W., et al 2018

    View details for DOI 10.1021/acsanm.8b02291

  • Creation of a dual-porosity and dual-depth micromodel for the study of multiphase flow in complex porous media LAB ON A CHIP Yun, W., Ross, C. M., Roman, S., Kovscek, A. R. 2017; 17 (8): 1462-1474


    Silicon-based microfluidic devices, so-called micromodels in this application, are particularly useful laboratory tools for the direct visualization of fluid flow revealing pore-scale mechanisms controlling flow and transport phenomena in natural porous media. Current microfluidic devices with uniform etched depths, however, are limited when representing complex geometries such as the multiple-scale pore sizes common in carbonate rocks. In this study, we successfully developed optimized sequential photolithography to etch micropores (1.5 to 21 μm width) less deeply than the depth of wider macropores (>21 μm width) to improve the structural realism of an existing single-depth micromodel with a carbonate-derived pore structure. Surface profilimetry illustrates the configuration of the dual-depth dual-porosity micromodel and is used to estimate the corresponding pore volume change for the dual-depth micromodel compared to the equivalent uniform- or single-depth model. The flow characteristics of the dual-depth dual-porosity micromodel were characterized using micro-particle image velocimetry (μ-PIV), relative permeability measurements, and pore-scale observations during imbibition and drainage processes. The μ-PIV technique provides insights into the fluid dynamics within microfluidic channels and relevant fluid velocities controlled predominantly by changes in etching depth. In addition, the reduction of end-point relative permeability for both oil and water in the new dual-depth dual-porosity micromodel compared to the equivalent single-depth micromodel implies more realistic capillary forces occurring in the new dual-depth micromodel. Throughout the imbibition and drainage experiments, the flow behaviors of single- and dual-depth micromodels are further differentiated using direct visualization of the trapped non-wetting phase and the preferential mobilization of the wetting phase in the dual-depth micromodel. The visual observations agree with the relative permeability results. These findings indicate that dual-porosity and dual-depth micromodels have enhanced physical realism that is pertinent to oil recovery processes in complex porous media.

    View details for DOI 10.1039/c6lc01343k

    View details for Web of Science ID 000399213700008

    View details for PubMedID 28294224

  • Controlled Design and Fabrication of SERS–SEF Multifunctional Nanoparticles for Nanoprobe Applications: Morphology-Dependent SERS Phenomena Journal of Physical Chemistry C Chang, S., Eichmann, S., Huang, T., Yun, W., Wang, W. 2017; 121 (14): 8070–8076

    View details for DOI 10.1021/acs.jpcc.7b00688

  • Microvisual investigation of polymer retention on the homogeneous pore network of a micromodel JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING Yun, W., Kovscek, A. R. 2015; 128: 115-127