Schlumberger scientists have developed the industry's first equation of state (EoS) for predicting asphaltene gradients in reservoir crude oils. This Flory-Huggins-Zuo EoS is based on the resolution of asphaltene colloidal science codified in the Yen-Mullins model. The latest generation DFA tool, the IFA, performs fluid measurements enabling use of this theory. Reservoirs that contain thermodynamically equilibrated asphaltene gradients are likely connected as established in IFA case studies. The combination of new asphaltene science and new DFA technology provides a powerful new way to evaluate reservoirs.