Origin of Oils Accumulated in Mesozoic-Cenozoic Reservoirs of the Iranian Sector of the Persian Gulf

Forty six oil samples from Aboozar, Bahrgansar, Dorood, Foroozan, Hendijan, Kharg, Nowrooz, Soroush (Kharg region), Balal, Resalat, Reshadat, Salman (Lavan region) and Sirri A, Sirri C, Sirri D and Sirri E accumulations (Sirri region) were geochemically characterised using biomarkers, stable carbon isotope composition, API gravity and sulphur content. Analysed oils have changeable gravities, from 10 to 39.2oAPI and sulphur content, from 0.63 to 3.77 wt. %. All investigated oils characterize comparable values of stable carbon isotope and biomarker composition. They were generated mostly from Type-IIS kerogen deposited in carbonates. The biggest differences are visible in the Kharg region and there a shale source rocks have greater contribution in source rocks than in the other regions.