In map-based fluid-flow modeling (pseudo-3-D), vertical leakage occurs through hydraulic fractures or by capillary top-seal failure related to capillary displacement pressure. Using empirical data sets, we have devised a method to estimate capillary displacement pressure of top seals. This method is based on top-seal lithology and porosity predictions, which allow estimations to be made of minimum, maximum, and most likely (e.g., P50) scenarios. Recently, this method has been incorporated into the SINTEF SEMI map-based modeling program, providing the capability to model change in top-seal capacity with depth (porosity). This enables the timing of hydrocarbon charge and phase to be integrated with top-seal capacity evolution through time. In this chapter, we show how the methodology is particularly useful in modeling fill-and-spill scenarios for charge of Tertiary reservoirs in the South Viking Graben. The same methodology has the potential to explain hydrocarbon phase and quality (gas-to-oil ratio and API gravity) in other charge scenarios.