Asphaltene nanoscience combined with InSitu Fluid Analyzer has delivered a major breakthrough in reservoir reconnaissance. In many, if not most, oil columns, molecular traces of asphaltene precipitate and settle on the column over geologic time. The physical parameters of the asphaltene form in the oil column form a â€˜fluid fingerprintâ€™ that can be used to solve compartmentalization and connectivity issues. The key is the ability to measure accurately these parameters insitu. The MDT Modular Formation Dynamics Tester tool together with its InSitu Fluid Analyzer provides this ability. Parameters measured include gradients in coloration, fluorescence, viscosity, fluid density, gas/oil ratio and hydrocarbon composition, all measured insitu and transmitted to the surface in real time. Interpretation of these measurements can mean the difference between a commercially viable well or an economic disaster.