Work on asphaltenes is important for several reasons and I think that different goals are best served with different definitions, or rather concepts.

Using the current definition of asphaltenes (pentane or heptane insolubles) as a solubility class of components in the oil, one might have reservoir oils with zero asphaltene content and still asphaltene problems are observed.  This is one reason I have (more or less) stopped using the term asphaltenes and instead refer to such problems as organic depositions.  At least that gives me one less problem namely; explaining to the operational personnel how we can have asphaltene problems with zero asphaltene content.

Due to the compositional continuum that crude oil is, the organic components that precipitate and eventually deposit and cause problems, will vary in composition.  Changes in pressure, temperature and composition (gas injection, pressure depletion, mixing of streams, etc) may lead to different types of organic deposition and the relation to the so-called pentane asphaltenes is hard to see.  I doubt that it is worthwhile to establish such a relation when there are good experimental techniques to determine the real phase diagrams (although more expensive).  Note that in the ‘de Boer’ diagram there is no explicit reference to the asphaltene content.

Other groups may have stronger need to define asphaltenes (refineries and heavy oil) but I think the best would be to get rid of the term, and rather see it as organic precipitation with reference to the actual process that generates it (might even use concepts from the theory of fouling).  This may help to keep focus on the understanding of the physical phenomena instead of getting lost in the definitions.

And, by the way, asphaltenes are not ‘…black, viscous and sticky..’ they are black, shiny, brittle and dry.