HYDROCARBON DISTRIBUTION IN THE IRATI SHALE OIL

This work reports a detailed characterization of the various hydrocarb on structures present in a sample of the Irati shale oil (Sao Mateus d o Sul, Parana), obtained by the Petrosix Process, by means of a combin ation of gas chromatography-mass spectrometry (g.c.-m.s.), co-injectio n with authentic standards, and retention time data of model compounds . Hydrocarbon structures, the main constituents of the shale oil (appr oximately 38 wt%), include: linear, branched and isoprenoidal alkanes, linear and isoprenoidal alkenes, alkylcyclopentanes and cyclohexanes, alkylcycloalkenes, hopenes, hopenes and steranes. Linear structures a re dominant (43% of the total hydrocarbons), followed by isoprenoidal skeletons. Saturated compounds strongly predominate over their unsatur ated counterparts. The use of several maturity parameters attested to the immaturity of the sediment. Our data further suggested a predomina nt algal/microbial origin and a basic lacustrine depositional environm ent to the Irati shale, probably under a moderate oxidative condition, thus confirming previous conclusions obtained via analysis of the Ira ti bitumen and the shale rock. Additionally, the data confirmed the us ual classification of this shale as containing Type-II kerogen.