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

Abstract

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) C 29 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.

Egypt far Western Desert basins petroleum charge system as defined by oil chemistry and unmixing analysis

“…Samples were chosen based on their organic richness and indications of in-situ staining as determined from LECO total organic carbon and programmed pyrolysis analysis. Similar oil to rock extract observations were made in several published studies (Alsharhan and Abd El-Gawad, 2008;Ghanem et al, 1999;Maky and Ramadan, 2008;Bakr, 2009;Sharaf and El Nady, 2003;Shalaby et al, 2011Shalaby et al, , 2012Moldowan, 2012, 2013). Note that the above studies, which include other Western Desert Basins (Kayanes and Abu Gharadig), indicate that a second more marine source facies is also present.…”

“…Previous Egypt Western Desert basin source rock and reservoir fluid studies indicate the potential for multiple Jurassic (Ras Quattara and Khatatba) and Cretaceous (Alam El-Bueib-AEB, Kharita, and Abu Roash) mature organic-rich source rocks, which could be expelling hydrocarbons over much of the Egypt Western Desert study area (Ghanem et al, 1999;Sharaf and El Nady, 2003;Alsharhan and Abd El-Gawad, 2008;Maky and Ramadan, 2008;Bakr, 2009;Shalaby et al, 2011Shalaby et al, , 2012Abrams et al, 2012;Younes, 2012;andMoldowan, 2012, 2013). The Egypt Western Desert reservoir fluids display highly variable fluid gravity as well as whole oil gas chromatograms.…”

Molecular Organic Geochemistry of Crude Oils from the Albertine Graben, Uganda: Possible Implications on the Expulsion of the Oils from the Source Rocks

“…For instance, archaebacterial lipids have been recently proposed as another source of phytane [14] while tocopherol as another source for pristine [15]. The oils also display low Pr/n-C 17 and Ph/n-C 18 ratios ( Table 2) suggesting high maturity due to the shift in n-alkane distribution from heavy to light components in the final stage of catagenesis [16]. GC data generally show a close similarity in the oils from the 6 oil fields.…”

Denizli Güneydoğusundaki (GB Türkiye) Kömürlerin Hidrokarbon Türetme Potansiyeli ve Biyomarker Özellikleri

“…Ayrıca örneklerdeki nC17/nC31 oranından da (0.02-0.11) anlaşılacağı gibi, C31 n-alkanların baskın olması organik maddenin karasal bitkilerden kaynaklandığına işaret etmektedir (Hunt, 1996;Kroon ve Castle, 2011). Karasal kökenli organik materyal miktarını belirlemenin bir diğer yolu, Ʃ(nC21-nC31)/Ʃ(nC15-nC20) oranı ile hesaplanan mumsuluk derecesidir (degree of waxiness) (Bakr, 2009). Çalışılan örneklerdeki Ʃ(nC21-nC31)/Ʃ(nC15-nC20) oranları YTK 17,YTK 25 ve YTK 28' de sırasıyla,11.08,24.14 ve 25.3 (Çizelge 4) olup, yüksek moleküler ağırlıklı n-alkanların miktarına bağlı olarak karasal bitki girdisine işaret etmektedir (Hedberg, 1968;Connan ve Cassou, 1980).…”