We fractionated a series of West African and West Australian crude oils into the four standard solubility classes: saturates, aromatics, resins, and asphaltenes (SARA). The asphaltene fraction was then separated further into classes we have called binding resins (BR) and residual asphaltenes (RA) using a solvent of near-boiling heptane. The ratio R equivalent to BR/RA correlates strongly with the tightness of water-in-oil emulsions that these oils formed either in the field or the laboratory. Crucially, only the oil with R > 1 did not form a stable emulsion and, for the oils which did, the smaller the value of R, the tighter the observed emulsion in terms of its longevity and separation characteristics. Two-dimensional GC-MS was used to analyze the resin and binding resin fractions, which lead to the preliminary identification of the main components.