In this paper, we present a perturbation-based theoretical model on the asphatene transport and aggregation in a pressure-driven microchannel flow. The aggregation effect is captured by a first-order reaction kinetics quantified by the appropriate Damkohler number. We find that the rate of average transport, quantified by the corresponding band velocity of a traveling asphaltene plug, is lowered by an increase in the Damkohler number, suggesting that the aggregation event lowers the flow rate of an asphaltene sample. Also, the average spread of the channel centerline concentration, described by a Gaussian profile and dictated primarily by the axial dispersion (and not Taylor dispersion, in light of the small Peclet number) increases with the Damkohler number. The net effect is a distinctly noticeable separation of asphaltene molecules having different rates of aggregate formation.