For condensates, the most important compositional variation is GOR, and the Equation of State (EoS) treatment of GOR variations is well developed and successful. Consequently, key reservoir attributes such as vertical and lateral connectivity, extrapolating gradients to obtain contacts for reserves estimation, and properties of the produced fluids are addressed by Downhole Fluid Analysis (DFA) measuring GOR and light end compositional variations. In contrast, black oils are defined as having low GOR; while black oils can exhibit GOR variations, the most important compositional variation of black oil is the heavy ends, essentially the asphaltenes. However, interpretation of asphaltene variations in reservoirs had been largely precluded because there had been no corresponding understanding of the governing principles of asphaltene science. Indeed, the field of asphaltene science had been in disarray. Consequently, there were no work flows to evaluate reservoirs using heavy ends in the way there are for condensates.

In recent years, several major advances have taken place in asphaltene science; these advances are in use by research groups around the world to address many issues such as heavy end upgrading, interfacial properties of asphaltenes, and flow assurance. Of particular interest in Exploration is that these scientific advances greatly improved the capability to use heavy ends to characterize reservoirs containing black oils as well as lighter crude oils including condensates. The confluence of advanced asphaltene science with the third generation of DFA tools enables a powerful new approach to address reservoir dynamics. Case studies have established that this new approach can lead to connectivity predictions that are proven by subsequent production. We describe the asphaltene science advances with emphasis on reservoir crude oils. We then outline DFA case studies of reservoirs that 1) illustrate corresponding advances in asphaltene science and 2) prove new methods for assessing reservoir connectivity, tar mats, biodegradation, reserves, location of mobile oil in heavy oil columns, flow assurance and other key reservoir attributes.