Understanding the processes that control the fate and transport behavior of biogeochemical elements in subsurface environments, requires understanding limiting controls operating at more than one scale. We propose to utilize the EMSL Cascade supercomputer and the eSTOMP simulator to address basic questions about processes of capillary trapping of non-whetting fluid phases (e.g. gas) migrating through deep aquifers; processes shown to potentially affect what may be the earths largest biosphere. The focus will be on the influence of mulitscaled (cm to km) and hierarchical sedimentary architecture of clastic aquifers, reflecting fluvial channel-belt genesis, on a gas phase invading water within the pore structures. The research will offer a theoretical perspective on how thermodynamic effects of differences in capillary pressure, across the boundaries of textural sedimentary facies organized within multi-tiered stratification, affect saturation and trapping of the non-whetting phase within pore structures. Success in this work will deepen our fundamental understanding of multiphase flow processes in subsurface environments, and our understanding of what controls the spatio-temporal distribution of gases within the subsurface biosphere.