Events

Speaker:  Dr. Xiaojing (Ruby) Fu, Geoscientist in the Juanes Research Group at Massachusetts Institute of Technology

Title of Seminar: “Modeling gas migration pathways through the lithosphere”

Abstract: Our planet is constantly emitting gas through the lithosphere. Naturally occurring gas emissions can be violent and episodic, such as volcanic eruptions; they can also be mild but persistent, such as methane seeps and hydrothermal vents. These natural phenomena transport a significant amount of carbon from the lithosphere into the ocean and the atmosphere; they also provide key insights to the subsurface structure that will help uncover valuable resources such as natural gas, oil and minerals.

My research seeks fundamental understanding of how gas migrates through the subsurface environment, with an emphasis on the interplay between multiphase flow---the simultaneous motion of several fluid phases---and phase transitions--- the creation or destruction of fluid or solid phases due to thermodynamically driven reactions. The framework of my analysis is that of phase-field modeling of multicomponent mixtures far from equilibrium.  Here I show that: (1) the interplay between phase separation and hydrodynamic instability can arrest the Ostwald ripening process characteristic of nonflowing gas-liquid mixtures; (2) partial miscibility exerts a powerful control on the degree of viscous fingering in a gas-liquid system, whereby fluid dissolution hinders fingering while fluid exsolution enhances fingering. Lastly, I employ this approach to explain observations of gas bubble expansion coupled with hydrate formation in controlled laboratory experiments. Unraveling this coupling informs our understanding of the fate of hydrate-crusted methane bubbles in the ocean water column and the migration of gas pockets in hydrate-bearing sediments.

Biography:  Ruby Fu is a geoscientist who studies multiphase and multicomponent flows in porous media through phase-field modeling and high-resolution simulations. Her work seeks to unravel the complex coupling between multicomponent thermodynamics (phase transitions) and multiphase hydrodynamics (flow instabilities) in geologic multiphase mixtures, and provides mechanistic understanding of their nonequilibrium behaviors. Fu then applies these understandings to advance the predictive capability of multiphase systems in Earth science applications, including sustainable use of fossil fuels through subsurface carbon storage, methane production from gas hydrates and prediction of natural geohazards such as volcanic eruptions and thawing permafrost.

In 2017, Ruby Fu obtained her PhD in Civil & Environmental Engineering from MIT supervised by Prof. Ruben Juanes. She is currently a postdoctoral associate at the Juanes research group. Starting in summer of 2018, Fu will be a Miller Research Fellow at UC Berkeley.