Critical drilling issues are usually associated with convergence of pore and fracture pressure, and are intimately connected to the downhole behavior of drilling fluids and uncertainties associated with predicting their behavior during well construction. Top areas of operational concerns, such as lost circulation, hole-cleaning, barite sag, wellbore stability, stuck pipe, etc. all share a common thread in hydraulics, and continue to plague drilling operations and efficiencies. From shallow sections to well completions, the drilling fluid and its imposed pressures represent the primary barrier for well control, and fluid hydraulics affects every stage of well construction. Current measurements provide at best a partial view of downhole pressure windows, and software technologies are necessary to fill in the gaps. A classic example includes optimum speeds for running casing where no downhole measurements currently exist.