Multiphase geosystems

Melt migration & partially molten materials

Partial melting is a fundamental process generating chemical heterogeneity in terrestrial planets. We develop models and numerical methods that to simulate the extraction of melt under mid-ocean ridges to address fundamental questions about the mantle structure under ridges, the chemical evolution of crust and mantle, the preservation of deep chemical signatures and the focusing of melt towards the ridge.

Geological CO₂ storage and natural CO₂ reservoirs

Geological CO₂ storage is currently the only option to mitigate anthropogenic CO₂ emissions from continued use of fossil fuels. Secure geologic storage of CO₂ requires an understanding of the long-term evolution of CO₂ in the subsurface. We aim to quantify the rates of the physical mechanisms that are likely to trap CO₂ underground. Trapping mechanisms are convective dissolution of CO₂ into the brine and the trapping of CO₂ as immobile phases by capillary forces on the pore scale.

Geomechanics and inverse problems

We study the effects of aquifer deformation on the pressure bulid-up in the storage formation and aim to link these models to measurements of surface deformation. Recent advances in satellite geodesy allow high resolution spatially distributed measurements of vertical displacements and promise to provide important spatial information on spatial variations in aquifer properties

To assimilate surface deformation data and other hydrologic observations into the flow models we are developing gradient/adjoint-based algorithms.

Fundamental processes

Convection in porous media

Convective motion introduced by temperature or concentration gradients is thought to be wide spread in sedimentary basins and the oceanic crust and often controls the rates of chemical and energetic exchange in geologic systems. We are interested in the determination of stability criteria for realistic hetero-geneous systems, as well as quantifying the fluxes in unstable systems. We are developing experimental systems that allow the quantification of convective fluxes in different scenarios, aim to develop scaling laws and other theories to explain the observed behavior and develop high resolution adaptive numerical methods that are benchmarked against physical data.

Two-phase flow in porous media

Two-phase flow is central to a large number of geological processes and environmental problems. We are developing models for two-phase gravity currents to understand the migration of non-wetting phases like CO₂ or non-aqueous contaminants in the subsurface. We are also working on theories for two-phase flow coupled with chemical reactions in the aqueous phase to determine the interaction of CO₂  with shallow groundwater aquifers. Accurate determination of migration velocities of CO₂ requires high resolution computations over very large areas and is currently not feasible on the field scale. We are interested in the development of adaptive numerical simulations that resolve the migrating CO₂ plume.

Reactive flow in porous media

The theory of hyperbolic conservation laws provides a unifying approach to the local equilibrium limit of reactive flow in porous media. We study the development of chromatographic patterns due to dissolution/precipitation, sorption, and two-phase flow with phase equilibrium.

Most minerals are not pure but complex solid solutions and the non-ideality can have important implications for high temperature systems as divers a melt migration and geothermal energy extraction. We are extending the hyperbolic theory to include solid solution and we are developing a numerical simulator for reactive porous flow with solid solution to capture these first order effects.