Comparison of Physical and Chemical Properties of the Oilfield Samples in the Iranian Sector of the Persian Gulf

Fifteen billion barrels of recoverable oil accumulated in 17 oilfields make the Iranian sector of the Persian Gulf one of the most proliferous regions in the world. The elemental and isotopic analyses as well as gas chromatography were conducted on 33 oil samples selected from different reservoirs in order to study the physical and chemical properties and identify the probable source rock characteristics. Most of the oil samples were characterized as the high sulfur content. The sulfur contents increase as API decreases. The Asmari reservoir of Kharg-Dorood oilfield contains the highest sulfur content whereas the Surmeh reservoir of Resalat oilfield has the lowest content. Different hydrocarbon fraction contents such as n-alkane distribution, acyclic isoprenoids ratios of pristane and phytane, carbon preference index, and stable carbon isotope ratios were determined by conducting the column chromatography, gas chromatography, and stable carbon isotopic analysis. Based on the results, most of the oil samples could be classified under paraffinic oils probably sourced from Mesozoic marine carbonate bearing type II and II-S kerogen deposited under anoxic condition.