Asphaltenes are organic solids which appear similar to paraffin waxes and in the field can be difficult to distinguish visually from waxes. However, they are very different in chemistry and should be treated using approaches different from those used for waxes. While there is still much debate as to the exact nature of asphaltenes, one common definition is that asphaltenes are the fraction of the crude which is insoluble in light normal alkanes but soluble in aromatic solvents. Their actual make-up depends on the conditions at which they precipitate out of solution.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards