Molecular modeling using structure elucidation programs in conjunction with molecular simulation programs has been performed on asphaltene molecules, the heaviest fraction of crude oil, in order to obtain a chemical model allowing us to tentatively study their physicochemical properties. We have analyzed Boscan asphaltenes (Venezuela) derived from a marine source rock. The different steps of this molecular modeling are described. First, a 3-D chemical representation of Boscan asphaltene is defined from an analytical data set. Second, the results of molecular dynamic simulations indicate that only a few stable conformations are possible due to the high reticulation of the model of the asphaltene unit obtained.