Molecular Organic Geochemistry of Crude Oil from Shushan and Abu Gharadig Basins, Western Desert, Egypt

Eight crude oil samples recovered from eight fields located in Abu Gharadig and Shushan basins in the north Western Desert, Egypt, were geochemically assessed in order to understand their genetic relationships. Two genetic families of oil are identified in this study, namely Abu Gharadig and Shushan oil families. Bulk (API and sulphur contents), n-alkanes, isoprenoids, biomarkers terpanes and steranes, and dibenzothiophene and phenanthrene parameters of the oils of the two families suggest regional variations of organic facies in their source rocks. Shushan samples represent oil typically generated from clay-rich terrigenous source rocks with great higher plant input, deposited under oxic conditions. Contrary, Abu Gharadig oil samples are of marine origin, their source rocks are rich in clay content and were deposited under suboxic environment. Biomarker maturity parameters Ts/Ts+Tm, ββ/αα and 20S/(20S+20R) C29 sterane ratios indicate that the studied samples had reached the peak of the oil window, with high maturity level biased towards Abu Gharadig oil. None of the studied oils have undergone biodegradation or water washing. This explains much of the chemical and physical properties uniformity observed across individual oil samples in each basin.