Biosketch

I am a geoscientist whose research focuses on the physics of flow and reactive transport in porous and fractured media. My research group combines high-performance numerical simulations, visual laboratory experiments, stochastic upscaling, and machine learning to elucidate how the coupling between multiple processes controls transport processes in fractured porous media (https://pkkang.com).

I joined the Department of Earth and Environmental Science at the University of Minnesota as an Assistant Professor and a Gibson Chair of Hydrogeology in 2018. I was a researcher at Korea Institute of Science and Technology (KIST) from 2015-2018, and was a postdoctoral associate in the Earth Resources Laboratory (ERL) at MIT before joining KIST. I received my MSc (2010) and PhD (2014) in Civil & Environmental Engineering at MIT, and obtained BSc of Civil, Urban & Geosystem engineering at Seoul National University in South Korea with summa cum laude in 2008.

Introduction of the Lecture

Fluid flow and reactive transport in geologic fractures control many critical natural and engineered processes in the subsurface. For example, 99% of global unfrozen freshwater is stored in groundwater systems, and groundwater flow is often dominated by fracture flows. Also, engineered carbon mineralization is considered a key solution for climate change, and fractures serve as highways for the delivery of CO₂ into mafic and ultramafic rocks, determining the efficiency of carbon mineralization. However, predicting transport processes in fractured porous media is challenging due to the multi-scale heterogeneity inherent to subsurface systems and the strong coupling between processes (i.e., coupled thermo-hydro-mechanical-biological-chemical processes).

In this talk, I will present how my research group uses cutting-edge methods to advance our fundamental understanding of coupled processes as well as our capacity to predict transport processes in fractured porous media. In particular, I will highlight the role of fluid inertia and pore-scale flow structures on transport, mixing, and biogeochemical reactions and our efforts to upscale transport processes in fractured porous media. The talk will conclude by sharing our ongoing efforts to extend the research findings to fractured aquifer sites.

Biosketch

Wen-lu Zhu is professor of Geology at the University of Maryland. She received her PhD at Stony Brook University in New York. Upon graduation, she worked as a research scientist at the Woods Hole Oceanographic Institution before joining the faculty at the University of Maryland. Wen-lu’s research focuses on the relationships between deformation and fluid flow. She conducts laboratory experiments and quantifies the change of the microstructure of deforming rocks in 3-D at in-situ pressure and temperature conditions. For her work in the field of rock deformation, she was awarded the 2020 Louis Néel Medal by the European Geosciences Union.

Introduction of the Lecture

Recent experimental studies show that high pore fluid pressure causes a transition from rapid and dynamic to quasi-stable faulting in compact rocks such as granites.  The stabilizing effect of pore fluid pressure on faulting can be explained by dilatant hardening—fault nucleation leads to creation of new void space, resulting in a decrease in pore fluid pressure and an increase in effective normal stress, which impedes further fault growth. It has been shown is that dilatant failure stabilization requires the deformation to be undrained, i.e., the rate of pore fluid pressure re-equilibration must be slower compared to the rate of deformation. Under laboratory loading rates, undrained conditions can be readily achieved in low permeability compact rocks. However, tectonic strain rates can be 6-10 orders of magnitude slower than laboratory strain rates. Thus, the stabilizing effect of pore fluid pressure observed in compact rocks may not be directly applicable in modeling rupture processes in nature. To circumvent the obvious physical limitation of conducting experiments at tectonic strain rates, we deformed porous sandstones with permeability 6-10 orders of magnitude higher than that of compact rocks at typical laboratory strain rates. Our experimental results show that porous sandstones subjected to high pore fluid pressures fail by slow faulting under fully drained conditions. We conducted quantitative microstructural analysis on deformed samples. Based on our findings, we proposed that the stress corrosion cracking played an important role in the pore fluid pressure stabilizing effect on fault propagation in porous rocks.

Biosketch

Wen-lu Zhu is professor of Geology at the University of Maryland. She received her PhD at Stony Brook University in New York. Upon graduation, she worked as a research scientist at the Woods Hole Oceanographic Institution before joining the faculty at the University of Maryland. Wen-lu’s research focuses on the relationships between deformation and fluid flow. She conducts laboratory experiments and quantifies the change of the microstructure of deforming rocks in 3-D at in-situ pressure and temperature conditions. For her work in the field of rock deformation, she was awarded the 2020 Louis Néel Medal by the European Geosciences Union.

Introduction of the Lecture

Recent experimental studies show that high pore fluid pressure causes a transition from rapid and dynamic to quasi-stable faulting in compact rocks such as granites.  The stabilizing effect of pore fluid pressure on faulting can be explained by dilatant hardening—fault nucleation leads to creation of new void space, resulting in a decrease in pore fluid pressure and an increase in effective normal stress, which impedes further fault growth. It has been shown is that dilatant failure stabilization requires the deformation to be undrained, i.e., the rate of pore fluid pressure re-equilibration must be slower compared to the rate of deformation. Under laboratory loading rates, undrained conditions can be readily achieved in low permeability compact rocks. However, tectonic strain rates can be 6-10 orders of magnitude slower than laboratory strain rates. Thus, the stabilizing effect of pore fluid pressure observed in compact rocks may not be directly applicable in modeling rupture processes in nature. To circumvent the obvious physical limitation of conducting experiments at tectonic strain rates, we deformed porous sandstones with permeability 6-10 orders of magnitude higher than that of compact rocks at typical laboratory strain rates. Our experimental results show that porous sandstones subjected to high pore fluid pressures fail by slow faulting under fully drained conditions. We conducted quantitative microstructural analysis on deformed samples. Based on our findings, we proposed that the stress corrosion cracking played an important role in the pore fluid pressure stabilizing effect on fault propagation in porous rocks.