Fluid flows in porous media are important to understand for a wide range of subsurface environmental and engineering applications, particularly in the case when two immiscible fluids are present (“two-phase flow”); this occurs during rainfall infiltration into the vadose zone, oil recovery, geologic CO₂ sequestration, containment of nuclear waste, geothermal energy production, and remediation of non-aqueous phase liquids. Significant research efforts have been devoted to understanding fluid transport in porous media, spanning back to the 1800’s and the days of Henry Darcy, but early understanding of flow processes was limited by the inability to directly observe fluid-fluid-solid interactions in opaque systems. Due to these constraints, a huge body of work has been developed based on a “black box” model: system parameters such as fluid flow rates, volumes, and pressures were measured at the inlet and outlet of porous media cores, and constitutive relationships were measured and used to infer the internal interactions between fluid phases and the solid architecture.

Recent advances in X-ray computed tomographic (CT) imaging and experimental technologies have enabled direct, high-resolution, internal 3D visualization of otherwise opaque samples; revealing that our established conceptual models and inferences of fluid flow behaviour are, in many cases, incorrect or incomplete. This talk will introduce multiple aspects of two-phase fluid flow physics that have recently been updated, thanks to new information from 3D X-ray CT imaging - including: nonwetting fluid invasion patterns, pressure signatures of fluid phases, and the importance of fluid topology to fluid trapping and mobilization.

Anna Herring studied environmental engineering (B.S. from University of Colorado, Boulder; and M.S. and Ph.D. from Oregon State University) because she is committed to resolving the conflicts between environmental protection and energy production necessary for modern life. Currently, she is an ARC DECRA postdoctoral fellow at the ANU, where her research enables efficient design and optimization of technologies used to fight climate change; including storing carbon dioxide in permeable underground geologic formations and in cements used in construction.