PoreLab lecture with Assistant Professor  Benzhong (Robin) Zhao on April 17th

Welcome to the next PoreLab lecture!

Who: Assistant Prof.  Benzhong (Robin) Zhao from McMaster University, Canada

The expertise of Dr. Benzhong Zhao is within climate change mitigation, renewable energy, water security, energy storage, carbon storage, multiphase flow, porous media and electrochemistry

When: Wednesday April 17th at 14:00 (Norway time).

Where:  The lecture will be streamed in the Kelvin room (PoreLab Oslo) and in the common room (PoreLab Trondheim). From anywhere else, you will be able to join via the following Zoom link: https://uio.zoom.us/j/65837085049?pwd=WjZianUyN3FJa2liQkxBbzQrOCtGdz09

Title: Pattern formation in fluid-fluid displacement through simple porous media


Intricate patterns often arise from fluid-fluid displacement in porous media. These patterns are not only aesthetically pleasing (see PoreLab’s “The Art of Porous Media” virtual exhibit) and scientifically interesting, but they also reveal clues of the underlying physical process that are important in the relevant subsurface applications. Here, I will discuss two recent studies in our lab.

The first study investigates fluid–fluid displacement in a Hele–Shaw cell where the two fluids react, upon mixing, to form solid precipitates. Although the injected fluids are viscously stable, the precipitation band that forms between the fluids becomes unstable to form finger-like flow channels compartmentalized by solid-deposited walls and clusters. The emergence, growth and decay of the fingering pattern are strongly influenced by the injection rate and the initial fluid chemical concentrations, which in turn exerts strong feedback on fluid-fluid mixing and the subsequent precipitation rate. We develop an advection-diPusionreaction- deposition model that captures the observed patterns and precipitation rate.

The second study investigates the impact of heterogeneous wettability (i.e., mixed-wet) on two-phase flow in porous media. Specifically, we study the displacement of silicone oil by water in a mostly oil-wet porous media patterned with discrete water-wet clusters. Surprisingly, the macroscopic displacement pattern varies dramatically depending on the details of wettability alteration—the invading water preferentially fills strongly water-wet clusters but encircles weakly water-wet clusters instead, resulting in significant trapping of the defending oil. We explain this counterintuitive observation with pore-scale simulations, which reveal that the fluid-fluid interfaces at mixed-wet pores resemble an S-shaped saddle with mean curvatures close to zero. We show that incorporation of the capillary entry pressures at mixed-wet pores into a dynamic pore-network model reproduces the experiments.