Joachim Moortgat and his research group study multiphase flow in porous and naturally fractured subsurface media. To model such processes, Moortgat has developed a versatile compositional reservoir simulator based on advanced higher-order finite element methods. Applications of interest are related to reservoir engineering, carbon sequestration in saline aquifers, groundwater remediation, and the production of shale oil and gas. To understand and predict the behavior of fluids in subsurface reservoirs, Moortgat's group studies problems spanning a wide range of scales: from complex thermodynamics and sorption processes at the molecular level in shale nano-scale confinements, to nonlinear multiphase flow (such as viscous and gravitational fingering) at both core- and field-scales. A wide range in spatial scales and rock properties is particularly challenging in fractured hydrocarbon reservoirs and aquifers, where fluids are mostly stored in the rock matrix, but flow may be predominantly through a network of high-permeability fractures with millimeter-scale apertures. The research in this group combines analytical/theoretical work with the development of sophisticated numerical methods and the analysis of laboratory experiments in collaboration with partners in academia and the petroleum industry.