Deep beneath the Earth's surface, oil and groundwater percolate through gaps in rock and other geologic material. Hidden from sight, these critical resources pose a significant challenge for scientists seeking to evaluate the state of such two-phase fluid flows. Fortunately, the combination of supercomputing and synchrotron-based imaging techniques enables more accurate methods for modeling fluid flow in large subsurface systems like oil reservoirs, sinks for carbon sequestration, and groundwater aquifers.